JP5356123B2 - Object detection device and electronic apparatus - Google Patents

Description

  The present invention relates to an object detection device that detects the presence or absence of an object by projecting pulsed light and detecting reflected light from the object, and more particularly to an object detection device mounted on a portable electronic device such as a mobile phone. is there.

  2. Description of the Related Art Conventionally, a detection device that is provided in an automatic door, an automatic cleaning device for sanitary equipment, an amusement device, or the like that detects the presence or absence of an object by projecting pulsed light and detecting reflected light from the object is well known. Examples of specific configurations include those disclosed in Patent Document 1 or Patent Document 2.

  In Patent Document 1, when the light receiving element detects light before the light emitting element projects light, the light receiving element waits until the light detecting element stops detecting light, and projects light from the light emitting element when no light is detected. An object detection device is disclosed.

  Patent Document 2 discloses a detection device that emits a plurality of times of pulsed light in one cycle and outputs a detection signal indicating the presence or absence of an object when the plurality of times of pulsed light are detected.

  In recent years, portable devices such as mobile phones and media players that are becoming increasingly multifunctional, miniaturized, or thinner have been equipped with sensors (object detection devices, proximity sensors) that detect the presence or absence of nearby objects. Yes. There are the following examples as the application.

  (1) ON / OFF control of a display screen backlight in a portable device having a telephone function and a display screen. For example, when the sensor detects the approach of human skin during a call, the backlight of the liquid crystal screen is turned off, and when the change to the non-proximity state is detected, the backlight is turned on again. By controlling the ON / OFF of the backlight in this way, the power consumption of the entire system is reduced.

  (2) ON / OFF control of a touch panel function in a portable device having a telephone function and a touch panel function. For example, the touch panel function is turned off when an object close to the sensor is detected during a call or when a device is inserted into a pocket. Thus, the malfunction of the system is prevented by controlling ON / OFF of the touch panel function.

  (3) A touchless switch in a portable device having a wireless communication function. For example, in a wireless mouse, a wireless keyboard, a game console controller, or the like by wireless communication, the device is activated when the operator brings a finger or hand close thereto, and sleeps when the operator moves away. By controlling the switch of the device in this way, the power consumption of the device is reduced.

  As described above, the object detection device (proximity sensor) is expected to be mounted on various devices such as mobile phones and media players, and the mounting conditions such as the mounting position and the surface state of the casing of the electronic device are electronic. Due to the design aspects of the equipment or design constraints, it varies from manufacturer to manufacturer or from model to model. Therefore, realization of an object detection device having equivalent characteristics (detection distance characteristics and malfunction) is strongly demanded even under various mounting conditions.

  Moreover, it is desired that the object detection device for the portable device application as described above has higher resistance to disturbance light such as sunlight and fluorescent light as compared with the conventional optical sensor technology. . At the same time, the object detection device realizes desired sensing characteristics such as desired sensing distance characteristics (sensing sensitivity) or response time in an extremely small mounting area, and it is also strongly desired that the proximity sensor itself has extremely low power consumption. ing.

  FIG. 15 shows an example of the configuration of a conventional object detection apparatus. FIG. 15A is a diagram of the object detection device viewed from the front (light incident surface), and FIG. 15B is a cross-sectional view of the object detection device. As shown in FIG. 15B, a light emitting element 100 such as an infrared light emitting diode (LED), a light receiving element 102 such as a photodiode, and an integrated circuit 104 for signal processing are mounted on a substrate 105, and each element is mounted. Are connected by a wire or the like.

  On the light emitting element 100 and the light receiving element 102, a light emitting lens 101 and a light receiving lens 103 are respectively formed of a resin that transmits infrared rays. The light emitting lens 101 condenses the radiated light from the light emitting element 100 on the object to be detected. The light receiving lens 103 condenses the reflected light from the non-detected object on the light receiving element 102. Other portions are covered with a resin 107 that does not transmit infrared rays. The resin 107 between the light receiving element 102 and the light emitting element 100 prevents radiation light and stray light components from the light emitting element 100 from entering the light receiving element 102.

  FIG. 16A is a diagram illustrating an example of a circuit configuration of a conventional object detection device. FIG. 17 shows an example of a signal processing waveform when the above circuit configuration is used. An example of the operation flow of object detection / detection in the conventional object detection device will be described with reference to FIGS.

  First, the light emitting element driving circuit 110 operates in accordance with the timing signal generated by the timing generation circuit 109 including an oscillator or the like, and pulse light is emitted from the light emitting element 100 (waveform A shown in FIG. 17). When there is an object to be detected, the light receiving element 102 receives reflected light from the object to be detected to generate a pulse signal, and the amplifier 111 amplifies the pulse signal (waveform B shown in FIG. 17). Then, a determination circuit 112 such as a comparator determines the presence or absence of a pulse (waveform C shown in FIG. 17). In the example shown in FIG. 17, the waveform C becomes Hi when the amplitude of the waveform B exceeds the threshold voltage Vth. Here, when the light receiving element 102 receives pulsed light in synchronization with the light emission timing of the light emitting element 100 (that is, the waveform C generated by the determination circuit 112 is Hi level at the light emission timing). In this case, the synchronization detection / signal processing circuit 113 inverts the output from the Lo level to the Hi level (latches) to indicate the “object detection” state. When there is no object to be detected, there is no reflected light from the object to be detected, so the above operation is not performed, the output remains at the Lo level, and the “object non-detection” state is entered.

  FIG. 16B is a diagram illustrating a circuit configuration example from the light receiving element 102 to the amplifier circuit 111 to the determination circuit 112. The circuit includes a photodiode 119 (corresponding to the light receiving element 102), a capacitor 120, an IV conversion amplifier circuit 151 (current-voltage conversion amplifier circuit), a dummy IV conversion amplifier circuit 152, a differential amplifier circuit 123, and a comparison. The determination circuit 124 is configured. The dummy IV conversion amplifier circuit 152 has the same configuration as the IV conversion amplifier circuit 151. The differential amplifier circuit 123 receives the output voltages of the IV conversion amplifier circuit 151 (current / voltage conversion amplifier circuit) and the dummy IV conversion amplifier circuit 152 as inputs.

  The configuration including the capacitor 120, the dummy IV conversion amplifier circuit 152, and the differential amplifier circuit 123 is intended to remove noise superimposed on the power supply voltage. Therefore, the pulse signal IV conversion amplifier circuit 151 and the dummy IV conversion amplifier circuit 152 need to have the same configuration and have the same gain frequency characteristics and output impedance.

  The IV conversion amplifier circuit 151 converts the optical signal received by the photodiode 119 into a voltage signal. On the other hand, no voltage signal is output to the dummy IV conversion amplifier circuit 152, and the AC amplitude is zero. Next, the differential amplifier circuit 123 amplifies only the voltage difference between the input voltage signals of the IV conversion amplifier circuit 151 and the dummy IV conversion amplifier circuit 152. Then, the comparison / determination circuit 124 compares the amplified signal with an arbitrary threshold voltage Vth to determine the presence / absence of a pulse.

  The IV conversion amplifier circuit 151 and the dummy IV conversion amplifier circuit 152 include operational amplifiers 115 and 117, resistors 116 and 118, and reference voltages 121 and 122, respectively. The output voltage of the IV conversion amplifier circuit 151 is a value obtained by multiplying the photocurrent flowing through the photodiode 119 when the reflected light is received and the resistance 116. Further, the bias voltage applied to both ends of the photodiode 119 (light receiving element 102) is the same voltage as the reference voltage 121 (in the case of an ideal operational amplifier, the input terminal is a virtual short) Node bias voltages are equal).

  When such an object detection device is mounted on a portable electronic device (housing) such as a cellular phone, the emitted light emitted from the light emitting element 100 is reflected on the surface of the electronic device housing (housing-air interface), The reflected light may be received by the light receiving element 102. At this time, in the object detection device, although there is no object to be detected, a malfunction that outputs a signal indicating the “object detection” state, or chattering that goes back and forth between the “detection” and “non-detection” states. It is a problem because such a phenomenon occurs.

  FIG. 18A is a diagram showing an outline when a conventional object detection device is mounted on an electronic device (housing) such as a mobile phone. FIG. 18B is a view of the light receiving element 102 shown in FIG. 18A viewed from the incident direction of the reflected light 128. As shown in the figure, the radiated light 126 radiated from the light emitting element 100 is projected onto the detected object 108 through the light emitting lens 101. The detected object 108 is disposed at a position away from the light emitting element 100 by a distance d1. The reflected light 128 from the detected object 108 is collected by the light receiving lens 103, forms the center of the spot 130 at a position away from the light emitting element 100 by the distance L 1, and is received by the light receiving element 102.

  Here, as shown in FIG. 18B, it is assumed that the reflected light 128 forms a spot 130 on the light receiving element 102 (actually, the reflected light 128 from the detected object 108 is condensed and received. The position of the light receiving element 102 and the characteristics of the light receiving lens 103 are adjusted and set so as to form a spot center on the element 102). At this time, when the radiated light 126 from the light emitting element 100 is reflected by the housing surface 127 away from the light emitting element 100 by the distance d2 (<d1), the reflected light 129 is also condensed by the light receiving lens 103 and is emitted. To the center of the spot 131 of the reflected light 129 at the position of L2 (> L1). Specifically, as shown in FIG. 18B, a spot 131 is formed outside the spot 130 of the reflected light 128 from the detected object 108, that is, in a direction away from the light emitting element 100. As shown in FIG. 18B, for example, when a light emitting element with low directivity such as an LED is used as a light source, the emitted light 126 projected from the light emitting element 100 at various angles onto the light receiving surface. Therefore, the spread of the spot is larger than the area of the light receiving element 102.

  FIG. 18C is a view of the light receiving element 102 shown in FIG. A waveform 132 represents the intensity distribution of the reflected light 128 from the detected object 108, and a waveform 133 represents the intensity distribution of the reflected light 129 from the housing surface 127 (the vertical direction represents the intensity distribution). As shown in the figure, even if the center point (the portion with the highest intensity) of the spot 131 of the reflected light 129 from the housing surface 127 is off the light receiving element 102, the reflected light intensity in the spot usually has a waveform 133. Because of such an intensity distribution, the light receiving element 102 receives the reflected light 129 from the housing surface 127 not a little.

  Further, the condensing position of the reflected light 129 from the casing surface 127 is based on the premise that the casing surface 127 is designed to be horizontal with the object detection device. However, the housing surface 127 is not always designed to be horizontal with the object detection device due to problems in the design of electronic equipment and design. For example, in a special case where the housing surface 127 is inclined with respect to the object detection device, the position is different from the spot position shown in FIG. 18B (for example, inside the light receiving element 102, that is, the light emitting element). It is necessary to consider that spots are formed in a direction close to 100).

  FIG. 19 shows output signal waveforms of each circuit when the light receiving element 102 receives the reflected light 128 from the detected object 108 and the reflected light 129 from the housing surface 127. FIG. 19A is a diagram showing a state in which the reflected light 129 component from the housing surface 127 (the broken line B shown in FIG. 19A or 19B) is weak and barely operates normally. On the other hand, FIG. 19B shows that the reflected light 129 component from the housing surface 127 is strong and the reflected light 129 from the housing surface 127 is not received although the reflected light 128 from the detected object 108 is not received. It is a figure which shows the state which is in a "detection" state only, ie, the state which is malfunctioning.

  The ease of occurrence of the malfunction depends on the distance d2 between the light emitting element 100 and the housing surface 127. For example, in the case shown in FIG. 18, if the distance d2 is long, the distance L2 between the light emitting element 100 and the center of the spot 131 of the reflected light 129 from the housing surface 127 becomes short, that is, the center of the light receiving element 102. The center of the spot 131 approaches. For this reason, the light reception current due to the reflected light 129 from the housing surface 127 increases, and the probability of malfunction occurring in the object detection device increases. Conversely, if the distance d2 is short, the distance L2 is long. Therefore, the light reception current due to the reflected light 129 from the housing surface 127 decreases, and the malfunction occurrence probability of the object detection device decreases.

  Here, since the distance d2 between the light emitting element 100 and the housing surface 127 has various values for each manufacturer and model of the electronic device to be mounted, a fundamental solution to the above problem is desired. The above problem is that L2 can be set long by mounting the distance d2 limited to an extremely short distance, or by mounting the object detection device barely (not mounted inside the electronic device). Although this can be avoided, in this case, the degree of freedom of design of the electronic device is reduced (design and design), which is a problem. Further, when the reflectance on the housing surface 127 changes suddenly (for example, a change in reflectance due to dirt or deterioration of the housing surface 127), the reflected light 129 component from the housing surface 127 increases. Therefore, there is still a possibility that a malfunction occurs, and from this reason, a fundamental solution to the malfunction due to the reflected light 129 on the housing surface 127 is desired.

  In Patent Documents 3, 4 and 5, the triangulation method is used as the method of the distance measuring sensor (sensor for measuring the distance of the detected object), thereby enabling accurate position detection of the detected object.

  Specifically, in Patent Document 3, the light receiving surface of the light receiving element is divided into two and the output level of one light receiving surface is always set higher than the output level of the other light receiving surface, and the outputs of the two light receiving surfaces are An optical detection sensor that calculates and detects the position of an object is disclosed.

  Further, in Patent Document 4, a photodiode having a plurality of light receiving surfaces is arranged at positions Pa to which reflected light from each of measured surfaces A to D near a plurality of predetermined working distances La to Ld is incident. A triangulation photoelectric sensor having a photodiode array arranged in parallel with Pd is disclosed. The triangulation photoelectric sensor described in Patent Document 4 can detect which working distances La to Ld the measurement target surface of the target object is by identifying each output of the photodiode array.

  Patent Document 5 discloses an optical semiconductor device including a light receiving element in which the ratio of a pair of output currents Ia and Ib varies according to the position of a light spot on the light receiving surface. The optical semiconductor device described in Patent Document 5 can measure the distance to the object by calculating the output currents Ia and Ib of the light receiving elements.

  The triangulation method used here uses a plurality of light-receiving elements (two-segment PD, PSD, PD array, etc.), measures the reflected light intensity from the object to be detected by each light-receiving element, and uses the triangle similarity condition. Is used to perform arithmetic processing, and the distance is detected from the result. Although this method can detect the distance to the reflecting object (detected object) due to the difference in the incident direction of the reflected light, it reflects the reflected light from the surface of the target case (that is, reflected at a very short distance). ) Does not refer to malfunction prevention measures. In addition, when there are a plurality of reflected lights, that is, when there is reflection from the object to be detected and reflection from the housing, there is a possibility that the detection distance may be reduced in accuracy or malfunction. In addition, the above method requires arithmetic processing such as addition, subtraction, and division, and an increase in the area of the integrated circuit chip and an increase in current consumption due to an increase in the number of components are inevitable.

  In Patent Document 6, as shown in FIGS. 20A and 20B, a dummy light receiving element 134 is arranged around a light receiving element 135 for signal reception, and light reception generated by the light receiving element 135 and the dummy light receiving element 134. When the arithmetic circuit 138 subtracts the current or differentially amplifies it after current-voltage conversion, the disturbance light 137 (broken arrow shown in FIG. 20A) is uniformly incident on the light receiving element 135, or the disturbance In the case where the light 137 is incident with an arbitrary intensity distribution, disturbance light components can be removed.

Japanese Utility Model Publication No. 6-18983 (published on March 11, 1994) JP 2006-145483 A (published June 8, 2006) Japanese Patent Laid-Open No. 10-300417 (published on November 13, 1998) Japanese Patent Laid-Open No. 6-249649 (published on September 9, 1994) JP 2006-220480 A (published August 24, 2006) JP 10-255300 A (published on September 25, 1998)

  Here, it is assumed that the light receiving element of Patent Document 6 receives reflected light from a light source with high directivity such as laser light. When receiving laser light, as shown in FIG. 20A, there is no problem because the reflected light spot diameter 136 is not widened. However, from the viewpoint of low power consumption, manufacturing cost reduction, safety, etc., an object detection apparatus that uses a light source with relatively low directivity, such as a light emitting diode, as the light emission source reflects as shown in FIG. The spread of the light spot diameter 136 ′ increases, and the light receiving surface of the light receiving element 135 may protrude. In this case, the signal light spot (reflected light from the detection object) also overlaps the light receiving surface of the dummy light receiving element 134. Therefore, the signal component received by the dummy light receiving element 134 is subtracted from the signal component received by the signal light receiving element 135, and there is a problem that the light receiving sensitivity of the object detection device is lowered.

  The problem of lowering the light receiving sensitivity due to the dummy light receiving element 134 can be compensated to some extent by increasing the amplification factor of the amplifier, adding a new amplifier, or expanding the area of the light receiving surface of the light receiving element 135. However, in this case, other problems such as a decrease in the S / N ratio due to an increase in power consumption and an increase in circuit noise and an increase in the cost of the IC chip and the light receiving element occur. In other words, this method is an inappropriate measure for an object detection device intended to be mounted on a portable electronic device. Therefore, it is necessary to consider a more fundamental measure, that is, a method in which the signal component is not removed while removing the reflected light component from the casing.

  Further, as described above, in a special case where the electronic device casing and the object detection device are not mounted in parallel, the reflected light spot position from the casing surface is different from the above, for example, a light emitting element. (In most cases, it is displaced in the direction of moving away as shown in FIG. 1b. It is a special case only). Such fluctuations in the reflected light spot position are not limited to the case where they are mounted non-parallel as described above, but are also irregular reflections when the surface of the housing is large, reflections at parts in electronic equipment, etc. This may occur even when the emitted light from the light emitting element propagates while reflecting between the casing and the object detection device and enters the light receiving element. That is, unnecessary reflected light noise caused by self-emission such as reflected light from the surface of the housing may vary depending on the type of electronic device on which the object detection device is mounted, the manufacturer, and the like. For this reason, the method disclosed in Patent Document 6 in which one light receiving element and one dummy light receiving element are paired eliminates the influence of unnecessary reflected light components formed at various positions. I can't do anything.

  The present invention has been made in view of the above-described problems, and its object is to reduce the output signal from the light receiving means to the comparison determining means due to the reflected light from the object to be detected. The object of the present invention is to realize an object detection device capable of preventing the comparison / determination means from outputting a signal indicating that the detected object has been detected by receiving the reflected light from the object other than the detected object.

  In order to solve the above-described problems, an object detection apparatus according to the present invention includes a light emitting unit that emits pulsed light, a light receiving unit that receives light, and a light reception timing of the light received by the light receiving unit. In the object detection apparatus including the detection means for detecting the presence or absence of an object to be detected by detecting whether or not it coincides with the emission timing of the light, the light receiving means includes the first light receiving element and the first light receiving element. A second light receiving element disposed adjacent to the light receiving element, and a third light receiving element disposed on the side opposite to the second light receiving element with respect to the first light receiving element. When the output signal of the first light receiving element is Ipd1, the output signal of the second light receiving element is Ipd2, and the output signal of the third light receiving element is Ipd3, the detection means is Iin = Ipd1- (Ipd2- Ipd3) No. Iin amplified, and the amplified signal is compared with a predetermined reference value, and characterized in that it is detecting the receiving timing of the light by the light receiving means.

  When the object detection device is used in an electronic device mounted in a housing, a light spot formed on the light receiving means by reflected light from an object to be detected outside the housing is a first spot, which is reflected from the housing. In the case where the light spot formed on the light receiving means by the light is the second spot, the second light receiving element is the first light receiving element, and the second spot is the first spot. It shall be arranged on the side deviating from the spot.

  At this time, according to the above configuration, the second spot due to the reflected light from the housing is formed shifted to the second light receiving element 202 side, and is received by the first light receiving element and the second light receiving element. (The light is not received by the third light receiving element). For this reason, the signal Iin used for detection by the detection means is Iin = Ipd1−Ipd2, that is, the output of the second light receiving element is subtracted from the output of the first light receiving element, which is a source of erroneous detection. The reflected light component from the body can be reduced.

On the other hand, the first spot due to the reflected light from the detection object outside the housing is received by the first to third light receiving elements. For this reason, the signal Iin used for detection by the detection means is Iin = Ipd1− (Ipd2−Ipd3), that is, the detection component of the second light receiving element is canceled by the detection component of the third light receiving element. Thereby, the detection sensitivity of the reflected light from the detection object is not lowered.

In the object detection apparatus, the signal Iin is changed to Iin = Ipd1− (Ipd2−Ipd3) by switching the connection for inputting the output signals of the first to third light receiving elements to the detection means. The signal can be switched between a signal represented by the equation (1) and a signal represented by the equation Iin = Ipd1− (Ipd3−Ipd2).

  According to said structure, even if the reflected light spot position from a housing | casing is formed in the reverse side of assumption by said switching, a response | compatibility is attained and the versatility of an object detection apparatus becomes high.

  In the object detection device, the light emitting means for emitting the pulsed light, the light receiving means for receiving the light, and the light reception timing of the light by the light receiving means coincide with the emission timing of the pulsed light by the light emitting means. In the object detection apparatus including detection means for detecting the presence or absence of an object to be detected, the light receiving means is disposed adjacent to the first light receiving element and the first light receiving element. A second light receiving element, and a third light receiving element disposed on the opposite side of the first light receiving element from the second light receiving element, and the output of the first light receiving element When the signal is Ipd1, the output signal of the second light receiving element is Ipd2, and the output signal of the third light receiving element is Ipd3, the output signal Ipd1 is connected to the first IV conversion amplifier, and the output signal The first I− corresponding to Ipd1 The output of the conversion amplifier is Vpd1, the output signal Ipd3 is connected to the first IV conversion amplifier, the output of the first IV conversion amplifier corresponding to the output signal Ipd3 is Vpd3, and The output signal Ipd2 is connected to a second IV conversion amplifier having the same resistance and reference voltage as the first IV conversion amplifier, and the second IV conversion corresponding to the output signal Ipd2 The output of the amplifier is Vpd2. Further, the second IV conversion amplifier has a capacitor having a capacitance value equal to the parasitic capacitance value of the first light receiving element in parallel with the second light receiving element. The first and second IV conversion amplifier outputs are input to a differential amplifier circuit, and the differential amplifier circuit amplifies the differential amplifier circuit. If the rate is Av, Vout = A X {Vpd1- (Vpd2-Vpd3)} The signal Vout represented by the equation is output to the detection means, and the detection means uses the signal Vout input from the differential amplifier circuit as a predetermined reference value. As a result, the light receiving timing of the light by the light receiving means can be detected.

  According to said structure, the 2nd spot by the reflected light from a housing | casing is shifted | deviated and formed in the 2nd light receiving element 202 side, and light is received by the 1st light receiving element and the 2nd light receiving element (3rd This is not received by the light receiving element). For this reason, the signal Vout used for detection by the detection means is Vout = Vpd1−Vpd2, that is, a case that causes false detection by subtracting the output of the second light receiving element from the output of the first light receiving element. The reflected light component from the body can be reduced.

On the other hand, the first spot due to the reflected light from the detection object outside the housing is received by the first to third light receiving elements. For this reason, the signal Vout used for detection by the detection means is Vout = Vpd1− (Vpd2−Vpd3), that is, the detection component of the second light receiving element is canceled by the detection component of the third light receiving element. Thereby, the detection sensitivity of the reflected light from the detection object is not lowered.

  The output of the second light receiving element and the output of the third light receiving element are input to an IV conversion amplifier having the same reference voltage. For this reason, the bias voltage when the output of the second light receiving element is IV converted and the bias voltage when the output of the third light receiving element is IV converted can be set to be the same. Therefore, more accurate subtraction processing can be performed.

  Further, by connecting a dummy capacitor to the IV conversion amplifier to which the second light receiving element is connected, the frequency characteristics of the first IV conversion amplifier and the second IV conversion amplifier are made the same. Power supply noise removal efficiency can be improved.

  Further, in the object detection device, the signal Vout is changed to Vout = Av × by switching the connection for inputting the output signals Ipd1, Ipd2, and Ipd3 to the first or second IV conversion amplifier. It is possible to switch between a signal represented by the expression {Vpd1- (Vpd2-Vpd3)} and a signal represented by the expression Vout = Av × {Vpd1- (Vpd3-Vpd2)}. Can do.

  According to said structure, even if the reflected light spot position from a housing | casing is formed in the reverse side of assumption by said switching, a response | compatibility is attained and the versatility of an object detection apparatus becomes high.

  In addition, even when the second light receiving element and the third light receiving element can be switched, the bias voltage when the output of the second light receiving element is IV converted and the output of the third light receiving element are The bias voltage at the time of IV conversion can be set to be the same, and the frequency characteristics of the first IV conversion amplifier and the second IV conversion amplifier are made the same to improve the power supply noise removal efficiency. .

  In the object detection apparatus, the second light receiving element and the third light receiving element are subdivided into a plurality of regions, and the signal Ipd2 is divided into a plurality of subdivided plurality of the second light receiving elements. The signal Ipd3 can correspond to an output from an arbitrary region among a plurality of subdivided regions of the third light receiving element. Can be configured.

  According to said structure, the light reception area | region area of a said 2nd light receiving element can be adjusted. That is, by this adjustment, it is possible to adjust the detection component of the second spot due to the reflected light from the casing to be close to zero, and the malfunction suppression effect is improved.

  In the object detection device, the light emitting means for emitting the pulsed light, the light receiving means for receiving the light, and the light reception timing of the light by the light receiving means coincide with the emission timing of the pulsed light by the light emitting means. In the object detection apparatus including detection means for detecting the presence or absence of an object to be detected, the light receiving means is disposed adjacent to the first light receiving element and the first light receiving element. A second light receiving element, and a third light receiving element disposed on the opposite side of the first light receiving element from the second light receiving element, and the output of the first light receiving element When the signal is Ipd1, the output signal of the second light receiving element is Ipd2, and the output signal of the third light receiving element is Ipd3, a current mirror circuit having a plurality of output stages, and the plurality of the current mirror circuits Each output of the output stage Switching means for switching between connection / disconnection of the current mirror circuit, and the output signal Ipd2 can be a signal Ipd2 ′ output through the current mirror circuit, and the output stage of the plurality of output stages of the current mirror circuit. By switching connection / disconnection of each output, the signal Ipd2 can be adjusted to have a predetermined amplification factor, and the detection means is a signal represented by an expression of Iin = Ipd1− (Ipd2′−Ipd3) By amplifying Iin and comparing the amplified signal with a predetermined reference value, the light receiving timing of the light by the light receiving means can be detected.

  According to said structure, the 2nd spot by the reflected light from a housing | casing is shifted | deviated and formed in the 2nd light receiving element 202 side, and light is received by the 1st light receiving element and the 2nd light receiving element (3rd This is not received by the light receiving element). For this reason, the signal Iin used for detection by the detection means is Iin = Ipd1−Ipd2 ′, that is, an error is caused by subtracting a predetermined multiple of the output of the second light receiving element from the output of the first light receiving element. The reflected light component from the casing that is the source of detection can be more accurately reduced. Therefore, the malfunction suppression effect is improved.

On the other hand, the first spot due to the reflected light from the detection object outside the housing is received by the first to third light receiving elements. For this reason, the signal Iin used for detection by the detection means is Iin = Ipd1− (Ipd2′−Ipd3), that is, the detection component of the second light receiving element is adjusted to be the detection component of the third light receiving element. By approaching, the detection components of the second and third light receiving elements are canceled. Thereby, the detection sensitivity of the reflected light from the detection object is not lowered.

  In the object detection device, the current mirror circuit receives the output signal Ipd2 or Ipd3 as its input by switching the connection for inputting the output signals Ipd1, Ipd2, and Ipd3 to the detection means. Therefore, the output can be the signal Ipd2 ′ or Ipd3 ′, and the signal Iin can be expressed as Iin = Ipd1− (Ipd2′−Ipd3) and Iin = Ipd1− (Ipd3′−Ipd2). It can be set as the structure which can be switched between the signals represented by this formula.

  According to the above configuration, even when the second light receiving element and the third light receiving element can be switched, the output signal Ipd2 or the output signal Ipd3 is multiplied by a predetermined value via the current mirror circuit, thereby Adjustment of the detection component of the second spot by reflected light from the body to be close to zero becomes possible, and the malfunction suppression effect is improved.

  In the object detection device, at least one of the first IV conversion amplifier and the second IV conversion amplifier includes a variable resistor, and the amplification factor is variable. Can do.

  According to the above configuration, by adjusting the output of at least one of the first IV conversion amplifier and the second IV conversion amplifier, the second spot due to the reflected light from the housing is adjusted. Adjustment to bring the detection component close to zero becomes possible, and the malfunction suppression effect is improved.

  In the object detection device, the detection means includes at least a timing generation circuit that generates a timing signal indicating the light emission timing of the light emission means, an amplification circuit that amplifies the output of the light reception means, and an output of the amplification circuit. A determination circuit that outputs a binary signal in comparison with a reference value of the signal, a synchronization detection circuit that detects synchronization between the binary signal output from the determination circuit and the timing signal generated by the timing generation circuit, A plurality of functional circuits including an output circuit for outputting a detection signal that the detected object is present when synchronization between the binary signal and the timing signal is detected in a synchronization detection circuit; and The plurality of functional circuits may be integrated on the same substrate.

  According to said structure, since the said light receiving element and the said detection means are formed on the same board | substrate, there exists a cost reduction effect by an occupation area reduction.

  In the object detection device, the substrate includes a first external input terminal to which a control signal for controlling each functional circuit constituting the detection circuit is input, and a second external input to which a clock signal is input. In order to perform reception sensitivity measurement on the input terminal, the shift register circuit for storing / setting the control signal according to the input of the clock signal, and the state of each functional circuit set by the control signal The test means can be provided.

  According to the above configuration, setting the control signal with the shift register facilitates the control of each functional circuit, so that a test in the mounted state is possible. In addition, the number of input terminals can be reduced, resulting in cost reduction and improved reliability.

  Further, the object detection apparatus includes a nonvolatile storage unit capable of storing the control signal input to the first external input terminal, and each functional circuit constituting the detection circuit is stored in the storage unit. It is possible to adopt a configuration that can be controlled by a control signal stored in

  According to the above configuration, the object detection device incorporates a writable nonvolatile memory such as a trimming fuse and a flash memory, generates a control voltage using the memory, and constantly applies the control voltage to each functional circuit. Thus, it is not necessary to apply (set) the control voltage from the outside during normal operation.

  In order to solve the above problems, an electronic device according to the present invention is an electronic device in which the object detection device described above is mounted in a housing, and the light reception is performed by reflected light from an object to be detected outside the housing. When the light spot formed on the means is the first spot and the light spot formed on the light receiving means by the reflected light from the housing is the second spot, the second light receiving element is The second spot is arranged on the side shifted from the first spot with respect to the first light receiving element.

Another electronic device according to the present invention, in order to solve the above problems, before Symbol object detection apparatus An electronic apparatus mounted in a housing, receiving the reflected light of the first in the housing This is a configuration provided with an erroneous detection preventing means for preventing erroneous detection by receiving light at the element .

  According to said structure, the malfunctioning prevention by housing | casing reflected light can be prevented by providing the erroneous detection prevention means by housing | casing reflection in an object detection apparatus.

In the electronic apparatus, the erroneous detection preventing means includes the second light receiving element or the third light receiving element that receives reflected light from the housing, and the erroneous detection preventing means includes the second light receiving element . The light component received by the light receiving means can be subtracted from the light component received by the first light receiving element .

According to the above configuration, the case reflected light is obtained by subtracting the case reflected light component received by the second light receiving element or the third light receiving element from the case reflected light component received by the first light receiving element. Can prevent malfunction.

Further, in the electronic apparatus, the erroneous detection preventing unit includes a unit that adjusts the reference value so that an output signal of the first light receiving element by reflected light from the housing is a non-detection region. It can be.

According to the above configuration, malfunction can be prevented by adjusting and optimizing the reference value by the amount of the reflected light component received by the first light receiving element .

  As described above, the object detection apparatus according to the present invention includes a light emitting unit that emits pulsed light, a light receiving unit that receives light, and a light reception timing of the light by the light receiving unit. In the object detection apparatus including detection means for detecting the presence / absence of an object to be detected by detecting whether or not they coincide with each other, the light receiving means includes a first light receiving element and the first light receiving element. A second light receiving element disposed adjacent to the first light receiving element, and a third light receiving element disposed on a side opposite to the second light receiving element with respect to the first light receiving element, When the output signal of one light receiving element or its amplified signal is Ipd1, the output signal of its second light receiving element or its amplified signal is Ipd2, and the output signal of its third light receiving element or its amplified signal is Ipd3, the detection means Is Iin = Ip 1 amplifies the (Ipd2-Ipd3) signal Iin represented by the formula, the amplified signal Iin is compared with a predetermined reference value, a configuration is possible detect a receiving timing of the light by the light receiving means.

  Therefore, when the object detection device is used in an electronic device mounted in a housing, if the first to third light receiving elements are appropriately arranged with respect to the formation position of the reflection spot, a housing that is a source of erroneous detection. The reflected light component from the body can be reduced and the detection sensitivity of reflected light from the object to be detected is not lowered.

BRIEF DESCRIPTION OF THE DRAWINGS The 1st Example of this invention is shown, (a) is a figure which shows the outline at the time of mounting an object detection apparatus in electronic devices (casing), such as a mobile telephone. (B) is the figure which looked at the light receiving element from the incident direction of reflected light. (C) is the figure which looked at each light receiving element of (b) from the side. A 1st Example is shown and (a) is a figure which shows an example of the circuit structure of an object detection apparatus. (B) is a figure which shows an example of the specific circuit structure of each light receiving element, an arithmetic processing circuit, and an amplifier circuit. It is a figure which shows the waveform of the output signal of each part of the object detection apparatus of a 1st Example. It is a figure which shows an example of the specific circuit structure of each light receiving element in the 2nd Example, an arithmetic processing circuit, and an amplifier circuit. It is a figure which shows an example of the concrete circuit structure of the switch means of a selector circuit in a 2nd Example. It is a figure which shows an example of the concrete circuit structure of each light receiving element of the object detection apparatus which is a 3rd Example, IV conversion amplifier, and a differential amplifier circuit. It is a figure which shows an example of the specific circuit structure of the light receiving element of the object detection apparatus which is a 4th Example, IV conversion amplifier, a differential amplifier circuit, and a selector circuit. FIG. 7 shows a fifth embodiment, and FIG. 5A is a diagram showing an example of a specific circuit configuration of a light receiving element, a selector circuit, and first and second IV conversion amplifiers of an object detection device. It is. (B) is the figure which looked at the 1st light receiving element of the object detection apparatus, the 2nd light receiving element, and the 3rd light receiving element from the incident direction of reflected light. It is a figure which shows an example of the specific circuit structure of the light receiving element of the object detection apparatus which is a 6th Example, the input stage of a current mirror circuit, the output stage of a current mirror circuit, and a selector circuit. It is a figure which shows an example of the specific circuit structure of the light receiving element of the object detection apparatus which is a 7th Example, IV conversion amplifier, and a differential amplifier circuit. It is a figure which shows an example of the circuit structure of the object detection apparatus which has a shift register circuit which is an 8th Example. FIG. 17 is a diagram illustrating an example of a control signal generation circuit of an object detection device including a trimming fuse according to a ninth embodiment. It is a figure which shows the circuit structural example to the light receiving element-amplifier circuit-determination circuit of the object detection apparatus which is a 10th Example. It is a figure which shows the waveform of the output signal of each part of the object detection apparatus of a 10th Example. It is a figure which shows a prior art and shows an example of a structure of the light emitting element and light receiving element of an object detection apparatus. FIG. 1 shows a conventional technique, and FIG. 1A is a diagram showing an example of a circuit configuration of a conventional object detection apparatus. (B) is a figure which shows the circuit structural example to a light receiving element-amplifier circuit-determination circuit. It is a figure which shows the waveform of the output signal of each part of the conventional object detection apparatus. FIG. 2A shows a conventional technique, and FIG. 1A is a diagram schematically illustrating a case where an object detection device is mounted on an electronic device (housing) such as a mobile phone. (B) is the figure which looked at the light receiving element from the incident direction of reflected light. (C) is the figure which looked at each light receiving element of (b) from the side. It is a figure which shows a prior art and shows the output signal waveform of each circuit in case a light receiving element receives the reflected light from a to-be-detected object and the reflected light from the housing | casing surface. FIG. 2 shows a conventional technique, and (a) and (c) are views showing a light receiving state of reflected light in a light receiving element and a dummy light receiving element. (B) is a figure which shows an example of a circuit structure of a light receiving element, a dummy light receiving element, and an arithmetic circuit.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 14 as follows. The object detection apparatus according to the present invention is particularly provided in a portable electronic device such as a mobile phone, and can prevent malfunction due to self-light emission such as reflected light on the surface of the casing of the electronic device. Hereinafter, various configurations and functions will be described in detail with reference to various examples.

[First embodiment]
The first embodiment of the present invention will be described with reference to FIGS. 1 to 3 as follows.

  FIG. 1 is a diagram showing an outline of an object detection apparatus 10 according to a first embodiment of the present invention. FIG. 1A is a diagram showing an outline when the object detection apparatus 10 is mounted on an electronic device (housing) such as a mobile phone.

  As illustrated, the object detection apparatus 10 includes a light emitting unit including at least one light emitting element 100 and a light emitting lens 101, a first light receiving element 201, a second light receiving element 202, a third light receiving element 203, and a light receiving element. A light receiving means including a working lens 102 and an integrated circuit 104. The object detection device 10 is mounted on an electronic device, and in FIG. 1A, a housing surface 127 of the electronic device is indicated by a solid line.

  The light emitting element 100 is realized by, for example, an infrared light emitting diode, and is a light source that projects light (pulsed light) onto an object to be detected. The light emitting lens 101 collects light projected by the light emitting element 100.

  The first light receiving element 201 receives reflected light 128 from the detected object 108. Further, the second light receiving element 202 and the third light receiving element 203 are disposed adjacent to the first light receiving element 201. As shown in the figure, the second light receiving element 202 is disposed adjacent to the far side from the light emitting element 100 on a straight line connecting the first light receiving element 201 and the light emitting element 100. On the other hand, the third light receiving element 203 is disposed adjacent to the side close to the light emitting element 100. The light receiving lens 102 condenses the reflected light from the detected object 108.

  Whether the integrated circuit (detection means) 104 detects the detected object 108 by receiving the output of the light receiving elements 201, 202, and 203, a circuit that controls the light emitting element 100 to emit light at a predetermined timing (emission timing). And a circuit for determining the above. Details of the integrated circuit 104 will be described later. A device including the second light receiving element 202, the third light receiving element, and the integrated circuit 104 is referred to as erroneous detection preventing means.

  Here, the object detection apparatus 10 projects light (projection light 126) from the light emitting element 100 to the detected object 108, and the reflected light 128 from the detected object 108 and the reflection from the housing surface 127 of the electronic device. Consider a case where the first light receiving element 201, the second light receiving element 202, and the third light receiving element 203 receive the light 129.

  FIG. 1B shows an irradiation state of the reflected lights 128 and 129 on each light receiving element at this time. FIG. 1B is a view of the light receiving elements 201, 202, and 203 viewed from the incident direction of the reflected light. In FIG. 1B, the solid circle indicates the spot 130 of the reflected light 128 from the detected object 108, and the broken line circle indicates the spot 131 of the reflected light 129 from the housing surface 127.

  As shown in the figure, the center of the spot 130 coincides with the center of the light receiving element 201, and the light receiving element 201 receives most of the reflected light 128 from the detected object 108. Further, the spot 130 partially extends to the light receiving elements 202 and 203, and the light receiving elements 202 and 203 also receive a part of the reflected light 128 from the detected object 108.

  Further, the center of the spot 131 is off from the center of the light receiving element 201, and the light receiving elements 201 and 202 receive the reflected light 129 from the housing surface 127.

  FIG. 1C shows the intensity distribution on the light receiving surface of the reflected lights 128 and 129. FIG.1 (c) is the figure which looked at each light receiving element of FIG.1 (b) from the side surface. In FIG. 1C, the solid line waveform 132 indicates the intensity distribution on the light receiving surface of the reflected light 128, and the broken line waveform 133 indicates the intensity distribution on the light receiving surface of the reflected light 129. The vertical axes of the waveforms 132 and 133 indicate the intensity, and the horizontal axis indicates the position. As illustrated, the peak of the intensity distribution of the reflected light 128 (the apex of the waveform 132) is at the center of the light receiving element 201. On the other hand, the peak of the intensity distribution of the reflected light 129 (the apex of the waveform 133) is off the center of the light receiving element 201.

  Next, the circuit configuration of the object detection apparatus 10 will be described. FIG. 2A is a diagram illustrating an example of a circuit configuration of the object detection apparatus 10. As illustrated, the object detection apparatus 10 includes a light emitting element 100, light receiving elements 201, 202, and 203 and an integrated circuit 104. The integrated circuit 104 includes a timing generation circuit 109, a light emitting element driving circuit 110, an arithmetic processing circuit 501, an amplification circuit 111, a determination circuit 112, a synchronization detection / signal processing circuit 113, and an output circuit 114. Note that these circuits included in the integrated circuit 104 are collectively referred to as functional circuits.

  The timing generation circuit 109 outputs a pulse signal indicating the timing at which the light emitting element 100 emits light to the light emitting element driving circuit 110 and the synchronization detection / signal processing circuit. The timing generation circuit 109 is composed of, for example, an oscillator.

  The light emitting element driving circuit 110 receives the pulse signal output from the timing generation circuit 109 and controls light emission of the light emitting element 100 according to the timing indicated by the received pulse signal.

  The light emitting element 100 emits light to the detected object 108 based on an instruction from the light emitting element driving circuit 110.

  The light receiving elements 201, 202, and 203 receive reflected light and output a received light current to the arithmetic processing circuit 501.

  The arithmetic processing circuit 501 receives and calculates the output of each light receiving element 201, 202, 203. Details of the calculation performed by the calculation processing circuit 501 will be described later. The arithmetic processing circuit 501 outputs a calculation result signal to the amplifier circuit 111.

  The amplifier circuit 111 receives a signal from the arithmetic processing circuit 501 and amplifies the signal. The amplifier circuit 111 outputs the amplified signal to the determination circuit 112. In the present application, the amplifier circuit 111 uses an IV conversion amplifier that converts the current signal output from the arithmetic processing circuit 501 into a voltage signal and amplifies it.

  The determination circuit 112 determines whether the value of the voltage signal that is the output of the amplifier circuit 111 exceeds a threshold voltage Vth (reference value). The determination circuit 112 outputs a Hi level signal to the synchronization detection / signal processing circuit 113 when the voltage signal output from the amplifier circuit 111 exceeds the threshold voltage Vth, and the voltage signal output from the amplifier circuit 111 is the threshold voltage. When it does not exceed Vth, a Lo level signal is output to the synchronization detection / signal processing circuit 113. The determination circuit 112 is configured by, for example, a comparator.

  The synchronization detection / signal processing circuit 113 detects whether the output signal of the determination circuit 112 is at the Hi level when the pulse signal output from the timing generation circuit 109 is at the Hi level. The synchronization detection / signal processing circuit 113 detects that the output signal of the determination circuit 112 is at the Hi level (detects synchronization) when the pulse signal output from the timing generation circuit 109 is at the Hi level. Then, a Hi level signal is output to the output circuit 114 until a Hi level pulse signal is received from the timing generation circuit 109. On the other hand, when the synchronization detection / signal processing circuit 113 detects that the output signal of the determination circuit 112 is not at the Hi level when the pulse signal output from the timing generation circuit 109 is at the Hi level, the next timing generation is performed. The Lo level signal is output to the output circuit 114 until a Hi level pulse signal is received from the circuit 109. That is, the synchronization detection / signal processing circuit 113 detects whether or not the timing (light reception timing) of the output signal of the determination circuit 112 coincides with the timing (emission timing) of the pulse signal output from the timing generation circuit 109. To do.

  The output circuit 114 outputs the output signal of the synchronization detection / signal processing circuit 113 to the outside of the object detection apparatus 10. When the signal output from the output circuit 114 is at the Hi level, the “object detection” state in which the object detection apparatus 10 detects the detection object is indicated. When the signal output from the output circuit 114 is at the Lo level, the “object non-detection” state in which the object detection apparatus 10 does not detect the detected object is indicated.

  Next, a specific circuit configuration and arithmetic processing of the arithmetic processing circuit 501 will be described with reference to FIG. FIG. 2B is a diagram illustrating an example of a specific circuit configuration of each of the light receiving elements 201, 202, 203, the arithmetic processing circuit 501, and the amplifier circuit 111. FIG. 2B shows an example in which the light receiving current generated by the light receiving element 202 is input to the arithmetic processing circuit 501 through the current mirror circuit 206. In addition, an example in which an IV conversion amplifier 214 is used for the amplifier circuit 111 and a photodiode is used for each of the light receiving elements 201, 202, and 203 is shown.

  Current mirror circuit 206 includes PMOS transistors 204 and 205. The IV conversion amplifier 214 includes a reference voltage (Vref) 207, an operational amplifier (operational amplifier) 208, and a resistor 209.

  The cathode of the second light receiving element 202 (photodiode) is connected to the input current node of the PMOS transistor 204 in the current mirror circuit 206. The cathode of the third light receiving element 203 is connected to the collector terminal (output current node) of the PMOS transistor 205. The cathode of the third light receiving element 203 is further connected to the cathode of the first light receiving element 201 and the input terminal of the IV conversion amplifier 214.

  Here, the light receiving current generated by the first light receiving element 201 is Ipd1, the light receiving current generated by the second light receiving element 202 is Ipd2, and the light receiving current generated by the third light receiving element 203 is Ipd3. The current input to the input terminal of the amplifier 214 is Iin. Here, the light receiving currents Ipd1, Ipd2, and Ipd3 are assumed to be currents flowing in the direction from the cathode to the anode of the photodiode. The light reception current Ipd2 generated by the light receiving element 202 is folded back by the current mirror circuit 206 and flows into the nodes of the first and third light receiving element cathodes. Therefore, according to Kirchhoff's law, the current Iin input to the IV conversion amplifier is as shown in the equation (A).

Iin = Ipd1- (Ipd2-Ipd3) (A)
That is, the arithmetic processing circuit 501 subtracts the light reception current Ipd2 by the light reception current Ipd3, and further subtracts the light reception current Ipd1 using the output current after the subtraction.

  As a result, as shown in FIG. 1B, the reflected light spot 131 (noise light that should not be detected) from the housing surface 127 becomes the reflected light spot 130 (signal light to be detected) from the detected object 108. In the case where it is formed so as to be shifted away from the light emitting element 100, the output signal by the reflected light 129 from the housing surface 127 is the light receiving current Ipd1 generated by the first light receiving element from the above formula (A). This is a value obtained by subtracting (housing reflected light) by the light receiving current Ipd2 (housing reflected light) generated by the second light receiving element. For this reason, the output signal of the reflected light 129 from the housing surface 127 becomes a suppressed value, and the possibility that the object detection device 10 erroneously detects is reduced.

  Further, as shown in FIG. 1B, even when the bottom of the reflected light spot 130 (signal) from the detected object 108 is formed so as to protrude from the light receiving surface of the first light receiving element 201, the signal spot. The light receiving current Ipd2 (signal) generated by the second light receiving element 202 due to the skirt is subtracted by Ipd3 (signal) generated by the third light receiving element 203 due to the signal spot skirt (in the parentheses in the expression A). Therefore, since the light receiving current Ipd1 generated in the first light receiving element is not subtracted, it is possible to avoid a decrease in light receiving sensitivity due to the dummy light receiving element.

  Therefore, with the above-described configuration, it is possible to realize a method in which the reflected light component (signal component) from the detected object 108 is not removed while the reflected light component from the housing surface 127 is removed.

  Next, the value of the output signal of each part of the object detection apparatus 10 will be described with reference to FIG. FIG. 3 is a diagram illustrating waveforms of output signals of the respective units of the object detection device 10. The vertical axis of each waveform in FIG. 3 represents the value of the output signal, and the horizontal axis represents time.

  The waveform N is a waveform indicating whether or not the detected object 108 that can be detected by the object detection apparatus 10 is actually present. When the waveform N is at the Hi level, it indicates that there is an object 108 that can be detected near the object detection device 10, and when the waveform N is at the Lo level, the object 108 that can be detected near the object detection device 10 is present. Indicates that it does not exist.

  A waveform A is a waveform of a pulse signal generated by the timing generation circuit 109. When the waveform A is at the Hi level, the timing at which the light emitting element 100 emits light is shown.

  A waveform Ipd1 is a waveform indicating the value of the light receiving current Ipd1 generated in the light receiving element 201. Similarly, waveform Ipd2 and waveform Ipd3 are waveforms indicating the values of light reception currents Ipd2 and Ipd3 generated by the light receiving elements 202 and 203, respectively. In the waveforms Ipd1, Ipd2, and Ipd3, the hatched portion indicates the value of the light reception current generated by the reflected light 129 from the housing surface 127, and the white background portion indicates the light reception current generated by the reflected light 128 from the detected object 108. Indicates the value.

  As shown in the figure, when the detected object 108 does not exist in the vicinity of the object detection device 10, the light receiving elements 201 and 202 receive the reflected light 129 from the housing surface 127 and generate a received current corresponding to the reflected light 129 component. It is generated (shaded area in FIG. 3). It is assumed that the light receiving current generated at this time is Ipd1 = Ipd2. Further, since the light receiving element 203 does not receive the reflected light 129, the light receiving current Ipd3 is not generated.

  On the other hand, when the object 108 that can be detected by the object detection apparatus 10 is present, the light receiving element 201 receives the reflected lights 128 and 129, and thus corresponds to a combination of the reflected light 128 component and the reflected light 129 component. Generate a light receiving current. Since the light receiving element 202 also receives the reflected lights 128 and 129, a light receiving current corresponding to a combination of the reflected light 128 component and the reflected light 129 component is generated. Since the light receiving element 203 receives only the reflected light 128, it generates a light receiving current corresponding to the reflected light 128 component. The light receiving element 201 receives more reflected light 128 than the light receiving elements 202 and 203. Therefore, the light reception current due to the reflected light 128 generated by the light receiving element 201 is larger than the light reception current due to the reflected light 128 generated by the light receiving elements 202 and 203. It is assumed that the light reception currents by the reflected light 128 generated by the light receiving elements 202 and 203 have the same value (the values of the white background portions of Ipd2 and Ipd3 in FIG. 3 are the same).

  A waveform Iin is a waveform indicating a value of a signal output from the arithmetic processing circuit 501 to the amplifier circuit 111. As shown in the figure, when there is no object to be detected, Iin = 0 from the above-described equation (A). On the other hand, when there is an object to be detected, the values of the shaded portions of Ipd1 and Ipd2 are the same, and the values of the white background portions of Ipd2 and Ipd3 are the same. Therefore, from equation (A), the value of Iin is the white background of Ipd1. It becomes the same value as the value of the part. That is, Iin is a value of the received light current corresponding to the reflected light 128 component received by the light receiving element 201.

  A waveform B is a waveform indicating the value of the signal output from the amplification circuit 111 to the determination circuit 112. A broken line indicates the value of the threshold voltage Vth. A waveform C is a waveform indicating the value of the signal output from the determination circuit 112 to the synchronization detection / signal processing circuit 113. As shown in the figure, the determination circuit 112 outputs a signal (waveform C) that becomes a Hi level when the value indicated by the waveform B exceeds the threshold voltage Vth.

  A waveform D is a waveform indicating a value of a signal output from the synchronization detection / signal processing circuit 113 to the output circuit 114. As shown in the figure, the synchronization detection / signal processing circuit 113 compares the waveform A and the waveform C, and outputs a signal that becomes Hi level when the Hi level is synchronized.

  Here, the advantage of including the second and third light receiving elements 202 and 203 is that the lowering of the light receiving sensitivity is prevented by not subtracting the skirt (protruding portion) component of the signal light spot 130, so that FIG. As in (b), it is important that the position of the formed signal light spot is set and arranged so that the bottom part of the spot can be received evenly on the second and third light receiving elements. Specifically, the second and third light receiving elements are disposed adjacent to the first light receiving element, and the third light receiving element is opposite to the second light receiving element with respect to the first light receiving element. It is preferable to arrange on the side.

  In FIG. 2B, the first light receiving element 201 and the third light receiving element 203 are separately configured. However, as described above, the reflected light spot on the housing is on the second light receiving element 202 side. In the case of being formed, the two light receiving elements may be constituted by one light receiving element (light receiving element area = light receiving element 201 + light receiving element 203 area).

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIGS. 4 and 5 as follows. In the first embodiment, as shown in FIG. 1, it is assumed that the reflected light 129 from the housing surface 127 shifts away from the light emitting element 100 (to the light receiving element 202 side). In this embodiment, an object detection device will be described that prevents malfunction even if the reflected light 129 is shifted to either the light receiving element 202 side or the light receiving element 203 side.

  The object detection device of the second embodiment is different from the object detection device 10 of the first embodiment in the circuit configuration of the arithmetic processing circuit 502. Since the configuration of the object detection apparatus of the second embodiment is the same as that of the object detection apparatus 10 except for the arithmetic processing circuit 502, the description thereof will be omitted.

  In the case where the reflected light spot 131 from the housing surface 127 is formed to be shifted to the light emitting element 100 side as opposed to FIG. The connection of the second light receiving element 202 and the third light receiving element 203 is switched, that is, the calculation processing of the light receiving currents Ipd2 and Ipd3 is switched. Thereby, the object detection apparatus of the second embodiment can prevent malfunction even if the reflected light 129 is shifted to either the light receiving element 202 side or the light receiving element 203 side.

  Hereinafter, a specific circuit configuration and processing of the arithmetic processing circuit 502 will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a specific circuit configuration of each of the light receiving elements 201, 202, 203, the arithmetic processing circuit 502, and the amplifier circuit 111 in the second embodiment. FIG. 4 shows an example in which light reception current generated by the light receiving element 202 and the light receiving element 203 is input to the arithmetic processing circuit 501 via the selector circuit 510. In addition, an example in which an IV conversion amplifier 214 is used for the amplifier circuit 111 and a photodiode is used for each of the light receiving elements 201, 202, and 203 is shown.

  The selector circuit 510 includes PMOS transistors 204 and 205 and switch means (selector means) 211 and 212. The switch units 211 and 212 are for switching the connection in accordance with the control signal 210.

  As shown, the cathodes of the second and third light receiving elements (photodiodes) 202 and 203 are connected to the collector terminals of the PMOS transistors 204 and 205, respectively. Further, the cathode of the second light receiving element 202 or the third light receiving element 203 is connected to the gate terminals of the PMOS transistors 204 and 205 via the switch means 212. Further, the cathode of the second light receiving element 202 or the third light receiving element 203 is connected to the cathode of the first light receiving element 201 and the input terminal of the IV conversion amplifier 214 via the switch unit 211. . As a result, the connection between the second light receiving element 202 and the third light receiving element 203 can be switched using the control signal 210. In other words, it is possible to switch between the arithmetic processing of the formula (A) and the arithmetic processing of the following formula (B) by the control signal 210.

Iin = Ipd1- (Ipd3-Ipd2) (B)
In FIG. 4, the switch means 211 and 212 show a state in the case of performing the calculation process of the formula (B). By switching both of the switch means 211 and 212 from the state of FIG. 4, a state in which the arithmetic processing of Expression (A) is performed is obtained.

  As described above, the arithmetic processing circuit 502 performs processing based on the formula (A) or (B) according to the control signal 210 according to the position of the reflected light spot 131 from the housing surface 127 formed on the light receiving surface. It is possible to switch. For this reason, it is possible to prevent malfunction due to the reflected light 129 in the same device (the object detection device of the second embodiment) regardless of which of the reflected light 129 from the housing surface 127 is shifted. Moreover, you may provide the 4th, 5th light receiving element (not shown) in the up-down direction of the 1st light receiving element 201 of FIG.1 (b). In this case, the output of each light receiving element is connected to the input of the IV conversion amplifier 214 via the arithmetic processing circuit (selector circuit) having the above-described configuration, whereby the vertical direction (FIG. 1B) It is possible to prevent malfunction even when the case reflected light appears.

  An example of a specific circuit configuration of the switch means 211 and 212 will be described with reference to FIG. As shown, the switch means 211 and 212 can be formed using a control signal source (Vcont) 300, a NOT circuit 301, and transfer gates (TG) 302 and 303. When the control signal Vcont = Hi, since the Hi level is applied to the NMOS gate of the TG 302 and the Lo level is applied to the PMOS gate, the TG 302 is turned on, whereas the TG 303 is turned off, and the terminal 1 is connected to the terminal 2. When the control signal Vcont = Lo, the TG 302 is non-conductive, the TG 303 is conductive, and the terminal 1 is connected to the terminal 3.

[Third embodiment]
The third embodiment of the present invention will be described with reference to FIG.

In the object detection apparatus 10 of the first embodiment, since the bias voltages applied to the second and third light receiving elements 202 and 203 are different from each other, the second and third light receiving elements 202 and 203 have the same amount of reflection. Even if the light 128 is received, the generated light receiving currents Ipd2 and Ipd3 differ. Therefore, the object detection apparatus 10 has a problem that current calculation is not accurately performed. (The bias voltage of the second light receiving element 202 is the gate voltage-GND potential of the current mirror circuit 206, and the bias voltage of the third light receiving element 203 is the Vref 207-GND potential.)
In order to solve this problem, the object detection device of the third embodiment differs from the object detection device 10 in that the circuit configuration between the light receiving element and the amplifier circuit is different. A circuit configuration between the light receiving element and the amplifier circuit of the object detection apparatus according to the third embodiment will be described with reference to FIG. The configuration of the object detection apparatus according to the third embodiment is the same as the configuration and processing of the object detection apparatus 10 except for the circuit configuration between the light receiving element and the amplifier circuit, and thus description thereof is omitted.

  FIG. 6 illustrates an example of a specific circuit configuration of the light receiving elements 201, 202, and 203, the IV conversion amplifiers 214 and 214 ′, and the differential amplifier circuit 215 of the object detection apparatus according to the third embodiment. FIG. As shown in the figure, the first light receiving element 201 and the third light receiving element 203 are connected to the first IV conversion amplifier 214. Further, the second light receiving element 202 and the capacitor 213 are connected to the second IV conversion amplifier 214 '. The output voltages of the respective IV conversion amplifiers 214 and 214 ′ are differentially amplified by the differential amplifier circuit 215.

  Here, the IV conversion amplifier output voltages to which the light receiving currents generated by the first, second, and third light receiving elements 201, 202, and 203 contribute are defined as Vpd1, Vpd2, and Vpd3, respectively. The capacitance value of the capacitor 213 is set to the same value as the parasitic capacitance of the first light receiving element 201. As a result, the output voltage Vout after differential amplification of the differential amplifier circuit 215 is represented by the following expression (C), where the amplification factor is Av.

Vout = Av × {Vpd1- (Vpd2-Vpd3)} (C)
As described above, each output voltage obtained by converting the light receiving current generated in each light receiving element by the IV conversion amplifier is subjected to subtraction processing in the same manner as in the equation (A). Therefore, it can be seen that the same effect as that of the object detection apparatus 10 of the first embodiment can be obtained by the object detection apparatus of the third embodiment.

  The bias voltages applied to the second and third light receiving elements are the reference voltages Vref207 ′ of the connected IV conversion amplifiers 214 ′ and 214, and the difference voltage between the Vref207 and the GND potential, By setting Vref 207 and Vref 207 ′ to the same value, the bias voltages applied to the second and third light receiving elements can be made the same. Therefore, in this case, the object detection apparatus of the third embodiment can perform more accurate subtraction processing.

  Furthermore, by connecting the same capacitance as the parasitic capacitance of the first light receiving element to the input of the second IV conversion amplifier, the gain frequency characteristics of the first and second IV conversion amplifiers are equivalent. Become. As a result, the power supply voltage noise removal efficiency in the differential amplifier circuit 215 in the subsequent stage can be improved.

  Also in the object detection apparatus of the third embodiment, the light receiving element 201 and the light receiving element 203 may be configured by one light receiving element (light receiving element area = light receiving element 201 + area of the light receiving element 203).

  When the first IV conversion amplifier 214 and the second IV conversion amplifier 214 ′ have the same configuration, the impedance Ziv of the IV conversion amplifiers 214 and 214 ′ is equal, so that the output voltage Vout is as follows: Can be calculated as follows.

Vout = Av × {Vpd1- (Vpd2-Vpd3)}
= Av * Ziv {Ipd1- (Ipd2-Ipd3)}
Therefore, when the first IV conversion amplifier 214 and the second IV conversion amplifier 214 ′ have the same configuration, the arithmetic processing in the third embodiment is equivalent to the arithmetic processing in the first embodiment. .

[Fourth embodiment]
The fourth embodiment of the present invention will be described with reference to FIG.

  The object detection apparatus of the fourth embodiment is obtained by adding switch means for switching the outputs of the light receiving element 202 and the light receiving element 203 to the circuit configuration between the light receiving element and the amplification circuit of the object detection apparatus of the third embodiment. is there. Therefore, the object detection apparatus of the fourth embodiment can prevent malfunction even if the reflected light 129 is shifted to either the light receiving element 202 side or the light receiving element 203 side.

  A specific circuit configuration between the light receiving element and the amplifier circuit of the object detection apparatus of the fourth embodiment will be described with reference to FIG. FIG. 7 shows specific examples of the light receiving elements 201, 202, and 203, the IV conversion amplifiers 214 and 214 ′, the differential amplifier circuit 215, and the selector circuit 520 of the object detection apparatus according to the fourth embodiment. It is a figure which shows an example of a circuit structure.

  Selector circuit 520 includes switch means 216 and 217. The switch means 216 and 217 switch connections according to the control signal 210.

  As shown in the figure, the switch means 216 connects the cathode of the light receiving element 202 or 203 to the input terminal of the IV conversion amplifier 214. Further, the switch means 217 connects the cathodes of the light receiving elements 202 and 203 to the input terminal of the IV conversion amplifier 214 '.

Thus, by connecting each light receiving element via the switch means 216, 217,
Even in a special case where the reflected light spot 131 from the housing surface 127 is formed on the side opposite to that in FIG. 1 (the light receiving element 203 side), the connection is switched according to the control signal 210 to obtain the expression (D). Calculation processing as shown can also be performed. At this time, the output voltage Vout of the differential amplifier circuit 215 is as follows.

Vout = Av × {Vpd1- (Vpd3-Vpd2)} (D)
In FIG. 7, the switch means 216 and 217 show the state in the case of performing the calculation process of the formula (C). By switching both of the switch means 216 and 217 from the state of FIG. 7, a state in the case of performing the arithmetic processing of Expression (D) is obtained.

  The object detection apparatus according to the fourth embodiment performs a malfunction even if the reflected light 129 is shifted to either the light receiving element 202 side or the light receiving element 203 side by performing arithmetic processing based on the formula (C) or (D). It is possible to prevent this, and more accurate calculation processing can be performed.

  As in the second embodiment, the fourth and fifth light receiving elements are arranged in the vertical direction in preparation for the case where the spot position of the case reflected light 129 is shifted in the vertical direction in FIG. The connection may be switched.

[Fifth embodiment]
The fifth embodiment of the present invention will be described with reference to FIG.

  Here, in the first to fourth embodiments, when each light receiving element receives only the reflected light 129 from the housing surface 127 (when the reflected light 128 is not received or there is no object to be detected), Expressions (A) and (C) are as follows.

Iin = Ipd1-Ipd2 (A) ′
Vout = Av × (Vpd1-Vpd2) (C) ′
In the first to fourth embodiments, the light receiving currents Ipd1 and Ipd2 of the light receiving elements 201 and 202 generated by the reflected light 129 have the same value. At this time, the input current Iin by the reflected light 129 from the housing surface 127 is zero. That is, the first to fourth embodiments show an ideal situation in which the efficiency of removing the reflected light component from the housing surface 127 is the highest.

  However, actually, the light reception current generated in each light receiving element varies depending on the area of the reflected light spot to be received, the intensity distribution of the reflected light, the distortion of the reflected light spot (by passing through the lens or resin), and the like. . Therefore, the light receiving currents Ipd1 and Ipd2 of the light receiving elements 201 and 202 generated by the reflected light 129 may not have the same value, and the input current Iin due to the reflected light 129 may not become zero.

  Therefore, adjusting the value of Ipd or Vpd so that the above formulas (A) ′ and (C) ′ become zero (or close to zero) can eliminate the reflected light component of the casing. Is very effective. Hereinafter, a method for adjusting Ipd or Vpd will be described.

  As shown in FIG. 8 (a), the object detection apparatus of the fifth embodiment arranges the second and third light receiving elements 202 and 203 in the object detection apparatus of the fourth embodiment in a subdivided manner, The subdivided light receiving elements are connected to the first and second IV conversion amplifiers via a selector circuit 220 that can switch the connection state of each of the light receiving elements. That is, the configuration of FIG. 8A has second light receiving elements 218a to 218d subdivided into four instead of the second light receiving element 202 in FIG. 1B, and the third light receiving element. Instead of 203, third light receiving elements 219a to 219d divided into four are provided. Of course, the subdivisions of the second and third light receiving elements are not limited to four in the above example. Further, the subdivided regions of the light receiving element do not have to have an equal area.

  The specific configuration of the light receiving element of the object detection device of the fifth embodiment is based on FIG. 8B, and the specific circuit configuration between the light receiving element and the amplifier circuit is based on FIG. 8A. explain. FIG. 8B shows the first light receiving element 201, the second light receiving elements 218a to 218d, and the third light receiving elements 219a to 219d of the object detection apparatus of the fifth embodiment viewed from the incident direction of the reflected light. FIG. As shown in FIG. 8B, the light receiving elements 218a to 218d are arranged adjacent to each other on the side far from the light emitting element in a straight line connecting the light receiving element 201 and the light emitting element 100. In addition, the light receiving elements 219a to 219d are arranged adjacent to each other on the side near the light emitting element in a straight line connecting the light receiving element 201 and the light emitting element 100.

  8A shows the light receiving elements 201, 218a to d, 219a to d, the selector circuit 220, and the first and second IV conversion amplifiers 221 and 222 of the object detection apparatus of the fifth embodiment. Is a diagram showing an example of a specific circuit configuration. The cathodes of the light receiving elements 218a to 218d and 219a to 218d are connected to the first and second IV conversion amplifiers 221 and 222 via the selector circuit 220, respectively.

  In accordance with the control signal, the selector circuit 220 connects the light receiving elements 218a to 219a and 219a to 219d to one of the first IV conversion amplifier 221, the second IV conversion amplifier 222, and the non-connection. Switch to. That is, the second and third light receiving elements 218a to 219a and 219a to 219d are switched between connection and non-connection with the first and second IV conversion amplifiers 221 and 222 according to the control signal. The light receiving current of the third light receiving element can be adjusted. That is, an effect equivalent to that of adjusting the light receiving area of the second and third light receiving elements can be obtained.

  The object detection apparatus according to the fifth embodiment provides an arbitrary control signal to the selector circuit 220, so that the right side of the expression (A) ′ is zero (or close to zero). It is possible to adjust the light receiving current of d. Therefore, the object detection apparatus of the fifth embodiment can remove the reflected light from the housing with high accuracy. At this time, it is also possible to adjust the light reception current of the third light receiving elements 219a to 219d in order to prevent the reception sensitivity from being lowered when receiving the signal light (reflected light 128). Further, the configuration of the object detection apparatus of the fifth embodiment is applicable not only in the case of the fourth embodiment but also in all of the first to third embodiments.

  In the fifth embodiment, as shown in FIG. 8, the second and third light receiving elements are each divided into four. The selector circuit 220 has two terminals for a total of eight light receiving element inputs. Here, when the connection of the total of eight light receiving elements 218a to 219a and 219a to d with the first and second IV conversion amplifiers 221 and 222 is controlled independently, the control signal that enters the selector circuit 220 is controlled. As a result, an 8-bit signal is required.

[Sixth embodiment]
The sixth embodiment of the present invention will be described with reference to FIG.

  Next, an object detection apparatus according to a sixth embodiment that adjusts the value of Ipd by an adjustment method different from that of the fifth embodiment will be described. The object detection apparatus according to the sixth embodiment includes a current mirror circuit 224 having a plurality of PMOS transistors at an output stage and a selector circuit 225 in the arithmetic processing circuit 501 of the object detection apparatus 10.

  A specific circuit configuration of the arithmetic processing circuit 501 of the object detection apparatus according to the sixth embodiment will be described with reference to FIG. FIG. 9 shows the light receiving elements 201, 202, and 203 of the object detection device of the sixth embodiment, the input stage (PMOS transistor) 223 of the current mirror circuit, the output stage 224 of the current mirror circuit, and the selector circuit 225. It is a figure which shows an example of a specific circuit structure. As shown in the figure, the cathode of the light receiving element 202 is connected to the input stage 223 of the current mirror circuit. Each output of the output stage 224 of the current mirror circuit is connected to the selector circuit 225. The output of the selector circuit 225 and the cathodes of the light receiving elements 201 and 203 are connected to an input terminal of an IV conversion amplifier 214 (not shown).

  In the object detection apparatus of the sixth embodiment, the selector circuit 225 switches connection / disconnection of each output of the output stage 224 of the current mirror circuit in accordance with the control signal, so that each output of the output stage 224 of the current mirror circuit is changed. Can be controlled. Therefore, the object detection apparatus of the sixth embodiment can output the light reception current Ipd2 generated by the second light receiving element 202 by multiplying it by a predetermined amount.

Here, the current output through the current mirror circuit is Ipd2 ′. The current Ipd2 ′ has the same value as the light reception current Ipd2 or a value obtained by multiplying the light reception current Ipd2 by a predetermined value. At this time, the current Iin input to the IV conversion amplifier 214 is
Iin = Ipd1- (Ipd2′-Ipd3) (A-2)
It becomes. Further, when each light receiving element receives only the reflected light 129 from the housing surface 127 (when the reflected light 128 is not received and there is no object to be detected), the equation (A-2) is as follows: become.

Iin = Ipd1-Ipd2 ′ (A-2) ′
In the current mirror circuit shown in FIG. 9, only the output stage 224 is composed of a plurality of PMOS transistors. However, the present invention is not limited to this, and the input stage 223 may be composed of a plurality of PMOS transistors. In this case, the light reception current Ipd2 can be decreased and output from the selector circuit 225 by inputting the light reception current Ipd2 to the plurality of PMOS transistors. For example, when the input stage 223 is composed of two PMOS transistors, the light receiving current Ipd2 generated in the light receiving element 202 from the selector circuit 225 can be multiplied by 1/2 and output.

  With this configuration, the object detection apparatus of the sixth embodiment can adjust the value of the light reception current Ipd2 generated by the second light receiving element 202 and input the adjusted value to the IV conversion amplifier 214. That is, the object detection apparatus of the sixth embodiment can adjust the right side of the formula (A-2) ′ to zero (or adjust to approach zero), and the reflected light from the housing surface 127 Removal can be performed with high accuracy.

  In the configuration of FIG. 9, the signal corresponding to the output of the second light receiving element 202 is multiplied by a predetermined number. Here, as shown in the second embodiment, when the connection between the second light receiving element 202 and the third light receiving element 203 is switchable, the calculation according to the above-described equation (B). In the connection state in which the connection is performed, the connection is switched so that the signal corresponding to the output of the third light receiving element 203 is multiplied by a predetermined amount. Specifically, a switch means for switching the cathode of the light receiving element 203 to the input stage 223 of the current mirror circuit and switching the cathode of the light receiving element 202 to the input terminal of the IV conversion amplifier 214 may be provided. .

When the cathode of the light receiving element 203 is connected to the input stage 223 of the current mirror circuit, the current output through the current mirror circuit is Ipd3 ′. The current Ipd3 ′ is the same value as the light reception current Ipd3 or a value obtained by multiplying the light reception current Ipd3 by a predetermined value. At this time, the current Iin input to the IV conversion amplifier 214 is
Iin = Ipd1− (Ipd3′−Ipd2) (B-2)
It becomes.

[Seventh embodiment]
The seventh embodiment of the present invention will be described with reference to FIG.

  Next, an object detection apparatus of a seventh embodiment that adjusts the value of Vpd by an adjustment method different from the fifth and sixth embodiments will be described. The object detection apparatus of the seventh embodiment uses the gain (amplification factor) of the second IV conversion amplifier (gain variable IV conversion amplifier) 226 in the configuration of the third embodiment shown in FIG. The control signal can be adjusted.

  A specific circuit configuration of the object detection apparatus of the seventh embodiment will be described with reference to FIG. FIG. 10 is a diagram illustrating an example of a specific circuit configuration of the light receiving elements 201, 202, and 203, the IV conversion amplifiers 214 and 226, and the differential amplifier circuit 215 of the object detection apparatus according to the seventh embodiment. It is. As shown in the figure, the difference from the third embodiment is that the second IV conversion amplifier 226 includes a variable resistor 227 and adjusts the resistance value of the variable resistor 227 in accordance with the control signal.

  The object detection apparatus of the seventh embodiment can adjust the output voltage of the second IV conversion amplifier 226 by adjusting the resistance value of the variable resistor 227 according to the control signal. In other words, the object detection apparatus of the seventh embodiment can adjust Vpd2 (output amplitude) in the equation (C) ′, that is, it can be adjusted to Vpd1 = Vpd2. Removal is possible.

  In the above configuration, when the spot 130 of the signal light (the reflected light 128 from the detected object 108) is wide, Vpd2 ≠ Vpd3, so that the sensitivity at the time of receiving the signal light may be reduced. However, the adjustment of Vpd2 in the second IV conversion amplifier 226 is slight, and the light receiving sensitivity of the signal light does not significantly decrease.

  Also in the seventh embodiment, the light receiving element 201 and the light receiving element 203 may be configured by one light receiving element (light receiving element area = light receiving element 201 + area of the light receiving element 203).

  In the example illustrated in FIG. 10, the case where the second IV conversion amplifier 226 includes the variable resistor 227 has been described. However, the present invention is not limited to this. For example, the resistor 209 of the first IV conversion amplifier 214 may be variable. At this time, both the first and second IV conversion amplifiers may include variable resistors. In order to enable the above-described highly accurate case reflection light removal, at least one of the first and second IV conversion amplifiers includes a variable resistor, and the amplification factor is variable. I can do it.

  In the first to seventh embodiments, when a plurality of light receiving element connection switching means and light receiving sensitivity adjusting means are provided, the control signal for each adjusting means is supplied with a shift register circuit (not shown). It is desirable to use and set. Thereby, not only can the number of external input terminals of the object detection apparatus be reduced, but it is also easy to control each adjusting means from the outside of the object detection apparatus. Therefore, adjustment or testing can be performed in a state where the object detection device is mounted on an electronic device.

[Eighth embodiment]
The eighth embodiment of the present invention will be described with reference to FIG.

  Next, a case where the object detection device includes a shift register circuit will be described. FIG. 11 is a diagram illustrating an example of a circuit configuration of an object detection device (device) 238 having a shift register circuit 228 according to the eighth embodiment. As illustrated, the object detection device 238 includes a light receiving sensitivity adjustment unit 230, a selector unit 231, an IV conversion amplifier 232a, an IV conversion amplifier 232b, a differential amplification circuit 233, a comparison determination circuit 234, and an AD conversion circuit 239. , A shift register circuit 228, an external input terminal 235, a clock input terminal 236, and an external output terminal 237.

  The light receiving sensitivity adjusting means (light receiving element area adjusting means) 230 adjusts the light receiving current Ipd2 (Ipd3) so that Iin of the formula (A) 'or the formula (A-2)' is zero. Specifically, the adjustment method in the fifth or sixth embodiment is performed.

  The selector means 231 switches the connection between the second light receiving element 202 and the third light receiving element 203. Specifically, the selector means 231 is realized by the selector circuit 510 of the second embodiment, for example.

  The IV conversion amplifier 232b adjusts the output voltage Vpd2 (Vpd3) so that Vout in the formula (C) ′ is zero. Specifically, the IV conversion amplifier 232 is realized by, for example, the second IV conversion amplifier 226 of the seventh embodiment. Hereinafter, the light receiving current adjusting unit 230, the selector unit 231 and the IV conversion amplifier 232b are also referred to as adjusting units.

  The shift register circuit 228 transmits a control signal for each adjustment means to each adjustment means, and instructs adjustment of the received light current, switching of connection, or adjustment of amplification factor. The shift register circuit 228 receives each control signal from the outside of the object detection device 238 via the external input terminal 235 and receives a clock signal via the clock input terminal 236. Then, the shift register circuit 228 generates a control signal for each adjusting unit from the control signal received from the outside.

  The shift register circuit 228 includes a plurality of flip-flop (FF) circuits 229. Each flip-flop circuit 229 stores a control signal to be transmitted to each adjusting means. The flip-flop circuit 229 receives the control signal from the external input terminal 235 and stores the control signal according to the clock signal received through the clock input terminal 236.

  Thus, by using the shift register circuit 228, a control signal can be transmitted to each adjusting means. That is, the number of input terminals for inputting each control signal to the object detection device 238 can be reduced.

  Here, the number of input terminals of the object detection device 238 will be compared between the case where the object detection device 238 has a shift register circuit and the case where the object detection device 238 does not have a shift register circuit. If the control signal of each adjustment means is 4 bits, the object detection device 238 needs to have 12 signal input terminals (4 bits × 3) when the object detection device 238 does not have a shift register circuit. On the other hand, in the case where the object detection device 238 includes a shift register circuit, the object detection device 238 only needs to have one signal input terminal and one clock terminal, that is, a total of two terminals.

  This shows that the number of input terminals can be reduced when the object detection device 238 includes a shift register circuit. By reducing the number of input terminals, it is possible not only to prevent an increase in the area of the object detection device 238 but also to reduce the probability of electrostatic breakdown due to electrostatic noise or the like at the input terminals or their peripheral circuits. Therefore, the object detection device 238 can be reduced in size and cost, and the degree of design freedom can be increased when the object detection device 238 is incorporated into an electronic device. In addition, the reliability of the operation / processing of the object detection device 238 can be improved.

  Next, each adjustment means adjusts the light reception current or the output voltage, and an optimization test for bringing Iin of the formula (A) ′ or the formula (A-2) ′ or Vout of the formula (C) ′ close to zero. A method will be described.

  First, arbitrary control signals (combinations thereof) are input to each adjustment means from the outside of the object detection device 238 via the shift register circuit 228, and each adjustment means is set to adjust according to the control signal. In the set state, the object detection device 238 emits pulses and emits the reflected light when there is an object to be detected and when there is no object to be detected (that is, when only the case reflection is received), for example. Light is received and the output voltage of the differential amplifier circuit 233 or the output of the comparison determination circuit 234 is measured.

  As shown in FIG. 11, the output voltage of the differential amplifier circuit 233 or the output of the comparison determination circuit 234 is converted into a digital signal by the AD conversion circuit 239 and stored in the flip-flop circuit 240 of the shift register circuit 228. . Then, the output voltage of the differential amplifier circuit 233 or the output of the comparison determination circuit 234 is output from the flip-flop circuit 240 to the external output terminal 237.

  When the measurement is completed, the object detection device 238 receives another control signal (a combination thereof), and again sets the adjustment means to adjust according to the newly received control signal. In the reset state, the object detection device 238 measures the output voltage of the differential amplifier circuit 233 or the output of the comparison determination circuit 234 in the same manner as described above. In this way, the measurement of the object detection device 238 is sequentially performed by changing the control signal (combination thereof). Then, a setting value (a combination of control signals) is determined that maximizes the difference between the output results when there is an object to be detected and when there is no object to be detected.

  During normal use (during operation) of an electronic apparatus including the object detection device 238, a combination of control signals obtained by the test method is input to the object detection device 238, and each adjustment unit performs adjustment according to the control signal. Always set as follows. This makes it possible to reduce the light receiving sensitivity of only the reflected light component (noise) from the housing surface without reducing the light receiving sensitivity to the reflected light (signal) from the object to be detected.

  Therefore, even if the object detection device 238 is mounted in various electronic devices, the light reception sensitivity of the object detection device 238 can be optimized in accordance with each mounting state. In other words, the object detection device 238 can be mounted on an electronic device and used under any mounting condition in the electronic device.

[Ninth embodiment]
The ninth embodiment of the present invention will be described with reference to FIG.

  In the case of the configuration like the object detection device 238 of the eighth embodiment, it is necessary to set the optimum combination of control signals obtained by the test method every time the object detection device 238 is operated. Therefore, the configuration of the object detection device 238 is not very realistic. For example, there is no particular problem if the control signal is a signal of several bits. However, if the number of bits of the control signal is increased, the control signal generation process for each adjusting unit becomes complicated.

  Therefore, in the ninth embodiment, instead of generating a control signal for each adjusting means in the shift register every time the optimal control signal obtained in the above test is received, the object detection device includes a nonvolatile memory, The control signal for each adjusting means generated from the optimal control signal obtained by the test is written in the memory. The object detection apparatus of the ninth embodiment includes a circuit that stores a control signal for each adjustment unit, so that it can always be set based on an optimum control signal for each adjustment unit. Note that examples of the non-volatile memory include a flash memory and a trimming fuse.

  Based on FIG. 12, the control signal generation circuit 410 of the object detection apparatus of the ninth embodiment having a trimming fuse will be described. FIG. 12 is a diagram illustrating an example of the control signal generation circuit 410 of the object detection apparatus according to the ninth embodiment including a trimming fuse. As illustrated, the control signal generation circuit 410 includes an external input terminal 401, a shift register unit 402, a trimming fuse element 403, an NMOS switch 404, and a resistor 405.

  The external input terminal 401 receives an input of the control signal Vcont during the test.

  The shift register means 402 receives the control signal Vcont via the external input terminal 401 during the test, and generates a control signal for each adjusting means.

  The fuse element 403 can switch the connection / disconnection state between the power supply and the NMOS switch 404 by fusing the fuse element 403 itself by a technique such as laser trimming.

  The output of the shift register means 402 operates as a shift register during a test, and can be switched so that the output becomes a Hi level during a normal operation. For example, the shift register is designed so that a test mode control signal (Vtm) can be input to the shift register to switch between a test time and a non-test time (normal operation time).

  First, the operation of the control signal generation circuit 410 during testing will be described.

  The control signal Vcont input from the external input terminal 401 is input via the shift register 402 to the gate of the NMOS switch 404 disposed in front of the control signal input unit of each adjusting unit. When Vcont = Hi, the NMOS switch 404 becomes conductive, and a current flows from the power supply Vcc to the resistor 405 via the fuse element 403, so that Vcont ′ = Hi. On the other hand, when Vcont = Lo, since the NMOS switch is non-conductive, no current flows through the resistor 405, so Vcont ′ = Lo.

  Next, the operation of the control signal generation circuit 410 during normal operation will be described.

  When the optimum control signal is determined after the test is completed and Vcont '= Hi is set according to the control signal, the fuse element 403 is not blown. On the other hand, when setting Vcont ′ = Lo, the fuse element 403 may be blown.

During normal operation, since the output of the shift register means 402 is always Hi as described above, the NMOS switch is always conductive, and if the fuse element 403 is not blown, current flows through the resistor 405, Vcont ′ = Hi. On the other hand, if the fuse element 403 is blown, Vcont ′ = Lo. Therefore, by selecting non-blown / blown fuse element 403, Vcont 'can be selectively set to Hi / Lo. (This Vcont 'is connected to each adjusting means of the internal circuit)
[Tenth embodiment]
The tenth embodiment of the present invention will be described with reference to FIGS. 13 and 14.

  In the first to ninth embodiments, the means for preventing malfunction by adjusting the signal input to the comparison / determination circuit has been described. In the tenth embodiment, the determination criterion in the comparison / determination circuit is adjusted. A means for preventing malfunction will be described.

  FIG. 13 is a diagram illustrating a circuit configuration example up to the light receiving element-amplifier circuit-determination circuit of the object detection apparatus according to the tenth embodiment. As shown in the figure, in the tenth embodiment, unlike the prior art, the threshold voltage (Vth) 241 of the comparison determination circuit 243 including the comparison circuit (comparator circuit) 242 is variable. The object detection apparatus of the tenth embodiment is configured to prevent erroneous detection due to reflected light from the housing surface by adjusting the threshold voltage (Vth) 241.

  Specifically, the object detection apparatus of the tenth embodiment receives various reflected light when there is no object to be detected (only the reflected light from the housing surface is received), and the comparison determination circuit By adjusting the threshold voltage to a value larger than the maximum value of the peak of the voltage amplitude Vpd1 input to 243, malfunction due to reflected light from the housing surface can be prevented.

  FIG. 14 shows waveforms of output signals of the respective circuits of the object detection apparatus of the tenth embodiment at this time. The broken line in the waveform B indicates the threshold voltage level before adjustment, and the thick solid line indicates the threshold voltage level after adjustment. It is apparent that malfunction can be prevented by adjusting the threshold level higher in accordance with the amplitude of the housing reflection component. In addition, when the signal of the second to third pulses in FIG. 14 is received (when the reflected light is received from the object to be detected), the amplification circuit output amplitude is originally an overlay of the housing reflection component and the signal component. Therefore, there is no change in sensitivity due to changing the threshold value.

  In the tenth embodiment, the determination criterion of the comparison determination circuit 243 is the threshold voltage Vth. However, of course, the comparison determination circuit 243 may be configured using the threshold current Ith.

  Further, when adjusting the threshold voltage Vth of the comparison determination circuit 243, it is desirable to set the output dynamic range of the differential amplifier circuit 215 large. This is because when the dynamic range is small, when the signal light or the case reflection light is received, the upper limit of the output amplitude is low, so if the input light is strong, the signal and the case reflection component cannot be distinguished. is there.

  Further, the tenth embodiment may be used in combination with the first to ninth embodiments, and in this case, it is possible to realize the malfunction suppression effect by the case reflected light with higher accuracy. Further, as in the eighth or ninth embodiment, a configuration may be adopted in which input setting means for a control signal from an external input terminal is provided so that the threshold level can be adjusted. As a test method at this time, the amplifier output amplitude Vpd1 (B shown in FIG. 14) in a state in which the object detection device is mounted on an electronic device or in a state close thereto (pseudo test) and there is no object to be detected. And the threshold level may be adjusted and optimized using the control signal in accordance with the peak level.

  In the object detection device of the present invention, it is preferable that all means except the light emitting means and the light receiving element are monolithically integrated. With this configuration, the area occupied by the constituent elements can be reduced, which leads to downsizing and cost reduction of the object detection apparatus. Further, since the wire (gold wire) connecting the integrated circuit and the light receiving element can be omitted, there is an effect that the influence of disturbance noise such as electromagnetic noise and coupling noise from output to input is reduced.

  In addition, an electronic device equipped with the object detection device of the present invention can test or adjust the object detection device in the manufacturing / testing process of the electronic device using the probability of malfunction caused by reflected light from the housing surface of the electronic device. By doing so, it is possible to optimize (reduce) the malfunction probability according to the mounting state, so design flexibility in the design / design of electronic equipment such as the mounting position of the object detection device and the material of the housing Will increase.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be used for the purpose of preventing malfunction due to self-light emission in an object detection device mounted on an electronic device such as a mobile phone.

DESCRIPTION OF SYMBOLS 10 Object detection apparatus 201 1st light receiving element 202 2nd light receiving element 203 3rd light receiving element 204,205 PMOS transistor 206 Current mirror circuit 207 Reference voltage 208 Operational amplifier 209 Resistance 210 Control signal 211, 212 Switch means 213 Capacitance 214 First IV conversion amplifier 214 ′ Second IV conversion amplifier 215 Differential amplifier circuit 216, 217 Switch means 218a-d Subdivided (four divisions) second light receiving elements 219a-d Subdivided ( Third light receiving element 220 divided into four) Selector circuit 221 First IV conversion amplifier 222 Second IV conversion amplifier 223 Current mirror circuit input stage (reference current)
224 Current mirror circuit output stage 225 Selector circuit 226 Variable gain IV conversion amplifier 227 Variable resistor 228 Shift register circuit 229 Flip-flop circuit 230 Light receiving sensitivity adjustment means 231 Selector means 232a IV conversion amplifier circuit (for signal)
232b Variable gain IV conversion amplifier 233 Differential amplification circuit 234 Comparison determination circuit 235 Control signal external input terminal 236 Shift register clock external input terminal 237 Shift register data external output terminal 238 Object detection device 239 AD conversion Circuit 240 Flip-flop circuit 241 for reading test results Variable threshold voltage 242 Comparison circuit (comparator circuit)
243 Comparison determination circuit 300 Control signal source (Vcont)
301 NOT circuits 302 and 303 Transfer gate 401 External input terminal 402 for control signal Shift register means 403 Fuse element (for trimming, non-volatile memory)
404 NMOS switch 405 Resistors 501, 502 Arithmetic processing circuit 510, 520 Selector circuit

Claims (14)

Light emitting means for emitting pulsed light;
A light receiving means for receiving light;
In an object detection apparatus, comprising: a detection means for detecting the presence or absence of an object to be detected by detecting whether the light reception timing of the light by the light reception means coincides with the emission timing of the pulsed light by the light emission means ,
The light receiving means is adjacent to the first light receiving element, the second light receiving element disposed adjacent to the first light receiving element, and the first light receiving element. A third light receiving element disposed on the opposite side of the second light receiving element,
When the output signal of the first light receiving element is Ipd1, the output signal of the second light receiving element is Ipd2, and the output signal of the third light receiving element is Ipd3,
The detection means includes
Iin = Ipd1- (Ipd2-Ipd3)
An object detection apparatus characterized in that the light reception timing of the light by the light receiving means can be detected by amplifying the signal Iin represented by the following formula and comparing the amplified signal with a predetermined reference value. By switching the connection for inputting the output signals of the first to third light receiving elements to the detection means,
The signal Iin is
Iin = Ipd1- (Ipd2-Ipd3)
A signal represented by the equation:
Iin = Ipd1- (Ipd3-Ipd2)
The object detection apparatus according to claim 1, wherein the object detection apparatus can be switched between a signal represented by the following formula. Light emitting means for emitting pulsed light;
A light receiving means for receiving light;
In an object detection apparatus, comprising: a detection means for detecting the presence or absence of an object to be detected by detecting whether the light reception timing of the light by the light reception means coincides with the emission timing of the pulsed light by the light emission means ,
The light receiving means is adjacent to the first light receiving element, the second light receiving element disposed adjacent to the first light receiving element, and the first light receiving element. A third light receiving element disposed on the opposite side of the second light receiving element,
When the output signal of the first light receiving element is Ipd1, the output signal of the second light receiving element is Ipd2, and the output signal of the third light receiving element is Ipd3,
The output signal Ipd1 is connected to a first IV conversion amplifier, the output of the first IV conversion amplifier corresponding to the output signal Ipd1 is set to Vpd1,
The output signal Ipd3 is connected to the first IV conversion amplifier, and the output of the first IV conversion amplifier corresponding to the output signal Ipd3 is set to Vpd3.
The output signal Ipd2 is connected to a second IV conversion amplifier having the same resistance and reference voltage as the first IV conversion amplifier, and the second IV corresponding to the output signal Ipd2 is connected. The output of the conversion amplifier is Vpd2,
Further, the second IV conversion amplifier has a state in which a capacitor having a capacitance value equal to the parasitic capacitance value of the first light receiving element is connected in parallel with the second light receiving element. Is possible to take
The first and second IV conversion amplifier outputs are input to a differential amplifier circuit, and the differential amplifier circuit has an amplification factor Av in the differential amplifier circuit.
Vout = Av × {Vpd1- (Vpd2-Vpd3)}
A signal Vout represented by the following equation is output to the detection means:
The object detection apparatus characterized in that the detection means can detect the light reception timing of the light by the light reception means by comparing the signal Vout input from the differential amplifier circuit with a predetermined reference value. By switching the connection for inputting the output signals Ipd1, Ipd2, and Ipd3 to the first or second IV conversion amplifier,
The signal Vout is
Vout = Av × {Vpd1- (Vpd2-Vpd3)}
A signal represented by the equation:
Vout = Av * {Vpd1- (Vpd3-Vpd2)}
The object detection apparatus according to claim 3, wherein the object detection apparatus can be switched between a signal represented by the following formula. The second light receiving element and the third light receiving element are subdivided into a plurality of regions,
The output signal Ipd2 can correspond to an output from an arbitrary region among a plurality of subdivided regions of the second light receiving element,
5. The output signal Ipd <b> 3 can correspond to an output from an arbitrary region among a plurality of subdivided regions of the third light receiving element. 6. The object detection apparatus described. Light emitting means for emitting pulsed light;
A light receiving means for receiving light;
In an object detection apparatus, comprising: a detection means for detecting the presence or absence of an object to be detected by detecting whether the light reception timing of the light by the light reception means coincides with the emission timing of the pulsed light by the light emission means ,
The light receiving means is adjacent to the first light receiving element, the second light receiving element disposed adjacent to the first light receiving element, and the first light receiving element. A third light receiving element disposed on the opposite side of the second light receiving element,
When the output signal of the first light receiving element is Ipd1, the output signal of the second light receiving element is Ipd2, and the output signal of the third light receiving element is Ipd3,
A current mirror circuit having a plurality of output stages;
Switching means for switching connection / disconnection of each output of the plurality of output stages of the current mirror circuit,
The output signal Ipd2 can be a signal Ipd2 ′ output through the current mirror circuit, and the signal can be switched by connecting / disconnecting the outputs of the plurality of output stages of the current mirror circuit. Ipd2 can be adjusted to a predetermined amplification factor,
The detection means includes
Iin = Ipd1− (Ipd2′−Ipd3)
An object detection apparatus characterized in that the light reception timing of the light by the light receiving means can be detected by amplifying the signal Iin represented by the following formula and comparing the amplified signal with a predetermined reference value. By switching the connection for inputting the output signals Ipd1, Ipd2, Ipd3 to the detection means,
The current mirror circuit can use the output signal Ipd2 or Ipd3 as its input, so that its output can be the signal Ipd2 ′ or Ipd3 ′.
The signal Iin is
Iin = Ipd1− (Ipd2′−Ipd3)
A signal represented by the equation:
Iin = Ipd1− (Ipd3′−Ipd2)
The object detection apparatus according to claim 6, wherein the object detection apparatus can be switched between a signal represented by the following formula.   5. The method according to claim 3, wherein at least one of the first IV conversion amplifier and the second IV conversion amplifier includes a variable resistor, and the amplification factor thereof is variable. Object detection device. The detection means includes at least a timing generation circuit for generating a timing signal indicating the light emission timing of the light emission means, an amplification circuit for amplifying the output of the light reception means, and comparing the output of the amplification circuit with a predetermined reference value. A determination circuit that outputs a value signal, a synchronization detection circuit that detects synchronization between the binary signal output from the determination circuit and the timing signal generated by the timing generation circuit, and the binary signal in the synchronization detection circuit And a plurality of functional circuits including an output circuit that outputs a detection signal that the detected object is present when synchronization with the timing signal is detected,
The object detection apparatus according to claim 1, wherein the light receiving unit and the plurality of functional circuits are integrated on the same substrate. The substrate is
A first external input terminal to which a control signal for controlling each functional circuit constituting the detection means is input;
A second external input terminal to which a clock signal is input;
A shift register circuit for storing / setting the control signal according to the input of the clock signal;
The object detection apparatus according to claim 9, further comprising: a test unit that performs reception sensitivity measurement with respect to a state of each functional circuit set by the control signal. Non-volatile storage means capable of storing the control signal input to the first external input terminal,
The object detection device according to claim 10, wherein each functional circuit constituting the detection unit can be controlled by a control signal stored in the storage unit. An electronic device in which the object detection device according to any one of claims 1 to 11 is mounted in a housing,
A light spot formed on the light receiving means by the reflected light from the detection object outside the casing is a first spot, and a light spot formed on the light receiving means by the reflected light from the casing is a second spot. If it ’s a spot,
2. The electronic apparatus according to claim 1, wherein the second light receiving element is arranged on a side where the second spot is shifted from the first spot with respect to the first light receiving element.   An electronic device in which the object detection device according to any one of claims 1, 2, 6, and 7 is mounted in a housing,
  The electronic device according to claim 1, wherein the reference value is a value larger than a maximum value of a peak of a signal amplified by the detection unit when the light reception unit receives only reflected light from the casing.   An electronic device in which the object detection device according to claim 3 or 4 is mounted in a housing,
  The electronic apparatus according to claim 1, wherein the reference value is a value larger than a maximum value of a peak of the signal Vout when the light receiving unit receives only reflected light from the housing.

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