JP5469446B2 - Object detection device - Google Patents

Description

  The present invention projects modulated light whose intensity changes over time into the target space, and measures the time difference from when the modulated light is projected until the reflected light from the object existing in the target space is received An object detection device that generates a distance image whose pixel value is a distance in the target space by obtaining a distance to the detection target and detects an object in a monitoring area defined in the target space using the distance image It is about.

  As an object detection device, a laser beam light or a laser slit light is scanned in a three-dimensional space region, and the distance to the object is measured for each scanning angle by measuring the distance to the object based on the time difference between light projection and reception. The technique to request | require is proposed (for example, patent document 1). In Patent Document 1, a region for monitoring an object is detected in three dimensions (voxels) in order to detect the position and movement of an object (including a person) in a spatial region to be monitored, and the object enters the set region. In addition, it is described that the control output and display output specific to the area are output to the outside.

  In addition, a configuration has been proposed in which an image sensor such as a CCD image sensor is used as a light receiving element for receiving reflected light from an object, and modulated light whose intensity changes over time is projected onto the entire field of view of the image sensor. Yes. By obtaining the distance from the timing at which modulated light is received in each light receiving area of the image sensor to the object for each light receiving area, a distance image having a pixel value as a distance is generated, and the object is detected using the distance image.

JP 2003-272061 A (paragraph [0156] etc.)

  By the way, adopting a configuration that scans the light to be projected in order to widen the target space for measuring the distance to the object requires a movable part such as a motor, and irregular measurement errors caused by vibrations occur. There arises a problem that it occurs or durability and reliability are lowered.

  On the other hand, in order to expand the target space without providing a movable part, it may be possible to use a configuration in which the distance to an object existing in the target space is measured using an image sensor, but the range in which light is projected Therefore, in order to secure the received light intensity, it is necessary to increase the energy of the light to be projected, resulting in a problem of increased power consumption.

  The present invention has been made in view of the above-mentioned reasons, and its purpose is not to have a movable part, and has high durability and reliability, and further, power consumption required for projecting to a required monitoring area. An object of the present invention is to provide an object detection device capable of suppressing an increase.

In order to achieve the above object, the present invention provides a light emitting source that outputs modulated light whose intensity changes over time, and a light projecting method that projects the modulated light output from the light emitting source to a desired region of the target space. A light projecting means comprising an optical system, a plurality of light receiving regions arranged in a two-dimensional array, an image sensor that can output in accordance with the light receiving intensity of the light received for each light receiving region, and a field of view are defined and within the field of view. Each of the light receiving means including a light receiving optical system that makes the light of the light incident on the image sensor, and the time difference from when the light emitting source outputs the modulated light until the image sensor receives the reflected light of the modulated light from the object existing in the target space. An arithmetic processing unit that obtains a distance to an object for each light receiving region and generates a distance image using the obtained distance as a pixel value; and an object detection unit that detects an object in the target space from the distance image generated by the arithmetic processing unit. Prepared and flooded Stage, and a slit light forming unit and the spot light forming unit respectively for projecting light and a slit beam and the spot light in the field of view of the defined light receiving means by the light receiving optical system, and set by the slit light and the spot light It employs a configuration in which each projecting modulated light to monitoring region.

  In addition, an anamorphic optical system that adjusts the aspect ratio of the image so that the image of each monitoring region is projected in accordance with the size of the light receiving surface of the image sensor can be adopted as the light receiving optical system.

  The light receiving optical system can employ a configuration composed of a plurality of optical elements that project images of the respective monitoring areas onto different parts of the light receiving surface of the image sensor, and a low resolution area in the field of the light receiving means. In combination with a plurality of optical elements having different resolving power so as to form a high-resolution area, or a narrow-angle area and a wide-angle area in the field of view of the light receiving means. It is possible to employ a configuration formed by combining a plurality of optical elements having different viewing angles so as to form the above.

  Further, a plurality of light emitting sources associated with each monitoring area may be provided for the light projecting means, and a timing control unit for controlling the timing of outputting the modulated light for each light emitting source may be added.

According to the configuration of the present invention, the light projecting unit composed of the light source and the light projecting optical system projects slit light and spot light within the field of view of the light receiving unit defined by the light receiving optical system. and a parts and spot light forming unit, since each of the monitoring area set by the slit light and the spot light for projecting modulated light, may be projected light only the required monitoring area, the required monitoring area Can suppress an increase in power consumption while generating a distance image. Further, the light projecting means is composed of a light emitting source and a light projecting optical system, and since there is no need to provide a movable part, durability and reliability are improved. In addition, since it is necessary for the light projecting means to project light for each monitoring area, at least one of the light source and the light projecting optical system is provided. By configuring, the light receiving means is shared by all the monitoring areas, so that the configuration is simple and the increase in cost can be suppressed.

The presence together made from one of the two areas separated by a curtain-like surveillance region formed by slits light can be monitored movement of the object to the other, the monitoring region formed by spot light The object to be detected can be detected. That is, by combining two types of monitoring areas, it is possible to simultaneously detect the movement of the object between the two divided areas and the presence or absence of the object in the specific area.

  When the anamorphic optical system is adopted in the light receiving optical system, the wide monitoring area is accommodated within the range of the light receiving surface of the image sensor, and the narrow monitoring area is expanded to the range of the light receiving surface of the image sensor to increase the resolution. It can be compatible.

  If a configuration in which different parts of the light receiving surface of the image sensor are associated with each monitoring area is adopted as the light receiving optical system, it becomes possible to simultaneously monitor a plurality of monitoring areas with one image sensor. Further, if a configuration in which a low-resolution area and a high-resolution area are formed as the light receiving optical system, it can be shared by both a monitoring area that requires high resolution and a monitoring area that requires low resolution. . Furthermore, if a configuration with different viewing angles is adopted as the light receiving optical system, a part of the monitoring area in the field of view can be enlarged and monitored, and the monitoring area of interest can be monitored in detail.

  When a configuration for controlling the timing of outputting modulated light for a plurality of light emitting sources provided for each monitoring area is adopted as the light projecting means, the timing for projecting light is varied for each monitoring area. In addition, the entire light receiving surface of the image sensor can be used, and the monitor area can be monitored in detail even with an image sensor having a small number of light receiving areas.

It is a block diagram which shows embodiment. It is operation | movement explanatory drawing same as the above. It is a figure which shows the structural example of the light projection optical system used for the same as the above. (A) is a front view which shows an example of the light reception optical system used for the same as the above, (b) is a front view of a comparative example. (A) is a side view which shows the other example of the light reception optical system used for the same as the above, (b) is a front view. (A) is a side view which shows the further another example of the light reception optical system used for the same, (b) is a front view. It is a perspective view which shows the example which uses the same as an elevator.

  The object detection apparatus used in the present embodiment employs a configuration for detecting the state (existence / non-movement / movement) of an object using a distance image in which the values of pixels constituting the image are distance values. The distance image is generated by projecting light such as infrared light into the target space where the object is detected and receiving reflected light from objects (including people) existing in the target space. By using information corresponding to the time difference, the principle of time of flight is used to detect the distance to the object. That is, an active distance sensor that projects light emitted from the light projecting unit into the target space, detects light from the target space by the light receiving unit, and detects the distance to the object using the output of the light receiving unit is used. .

  The light projecting means emits modulated light whose intensity changes over time, and the phase difference between the modulated light reflected by the object and received by the light receiving means and the projected modulated light is calculated from light projection to light reception. Used as information corresponding to the time difference. As a modulation waveform of the modulated light, a sine wave, a triangular wave, a sawtooth wave, a square wave, or the like can be used. When a sine wave, a triangular wave, or a sawtooth wave is used, the period of the modulated light is set to a constant period. When square waves are used, the period of the modulated light is set to a constant period, and the ratio between the on period (light projecting period of the light projecting means) and the off period (non-light projecting period of the light projecting means) is randomized. It is also possible to adopt a technology that changes the process.

  The light receiving means includes an imaging device in which a plurality of pixels are arranged two-dimensionally. As the image pickup device, a well-known configuration for picking up a gray image provided as a CCD image sensor or a CMOS image sensor can be used. However, the image pickup device is designed specifically to have a structure suitable for a distance sensor. It is desirable to use

  The latter image sensor has a basic structure similar to an image sensor having a well-known configuration for capturing gray images. However, each pixel has a plurality of light receiving areas, and the light receiving sensitivity for each light receiving area can be controlled by an electric signal. In each light receiving region, a charge having a charge amount corresponding to the received light intensity is generated. The light receiving sensitivity of the light receiving region is controlled in order to detect information including a phase difference between light projection and light reception by controlling the timing of receiving the modulated light.

  This imaging device has an accumulation region for accumulating charges generated in each light receiving region over an integer multiple of the modulation period of the modulated light, and further, an environment that is not modulated light among the charges generated in the light receiving region. In some cases, a function of reducing light or ambient light components is provided.

  In the following, for the purpose of facilitating the understanding, the following configuration is assumed as an example of the configuration of the distance sensor, but this configuration is not intended to limit the present invention, but the modulation waveform of the modulated light, the configuration of the imaging device, the imaging device With respect to the control and the like, the configurations provided in various known distance sensors can be used.

  As shown in FIG. 1, the distance sensor A used in the following description includes a light emitting source 1 that emits light (desirably using near infrared rays) and an image sensor 2 that receives light from a target space. As the light emitting source 1, a light emitting element such as a light emitting diode or a laser diode capable of obtaining a light output proportional to an instantaneous value of input is used. Further, in order to secure the amount of light emitted from the light source 1, the light source 1 is configured using an appropriate number of light emitting elements.

  The light emitting source 1 constitutes a light projecting unit together with a light projecting optical system 3 that projects the modulated light output from the light source 1 into the target space. Further, the image sensor 2 constitutes a light receiving means together with a light receiving optical system 4 that makes light from the target space incident on the image sensor 2. The light projecting optical system 3 and the light receiving optical system 4 are arranged close to each other, and the distance between the light projecting optical system 3 and the light receiving optical system 4 can be substantially ignored with respect to the field of view. .

  In the distance sensor A, a modulation signal generation unit 5 that outputs a modulation signal for driving the light emission source 1 and a light reception timing at the image sensor 2 based on the modulation signal output from the modulation signal generation unit 5 are defined. A timing control unit 6 that generates a light reception timing signal, an arithmetic processing unit 7 that generates a distance image by obtaining a distance to an object existing in the target space using the light reception signal output from the image sensor 2, and an arithmetic processing unit And an object detection unit 8 that extracts information such as the presence / absence of an object in the monitoring region and the movement of the object from the distance image generated in 7.

  The modulation signal generation unit 5 generates a modulation signal whose output voltage changes with a sine waveform having a constant frequency (for example, 20 MHz), and supplies the modulation signal to the light emission source 1, as shown in FIGS. Then, modulated light whose light output changes in a sine wave shape is emitted from the light source 1. When a light-emitting diode is used as the light-emitting source 1, a modulation signal is emitted by changing a current flowing through the light-emitting diode by applying a signal voltage of a modulation signal to the light-emitting diode via a current limiting resistor.

  On the other hand, the image pickup device 2 is provided with one light receiving region for each pixel. In this case, by using the electronic shutter technique, it is possible to generate a charge corresponding to the light reception intensity only during a period synchronized with the light reception timing signal. In addition, the charge generated in the light receiving region is transferred to the light-shielded accumulation region and accumulated in the accumulation region in the accumulation period corresponding to a plurality of periods (for example, 10000 periods) of the modulation signal. Is taken out as a light receiving output.

  The timing control unit 6 generates a light reception timing signal synchronized with the modulation signal. Here, four different light receiving timing signals are defined for defining four different phases in one cycle of the modulation signal, and setting a light receiving period having a certain time width for each phase, and four kinds of light receiving timing signals for each accumulation period. 1 is provided to the image sensor 2.

  That is, the process of accumulating the charge generated in the light receiving region in the light receiving region defined by one type of light receiving timing signal in one accumulation period, and taking out the accumulated charge as a light receiving output to the outside of the image sensor 2 is repeated four times. Light reception outputs corresponding to four types of light reception timing signals are taken out of the image sensor 2 in four accumulation periods.

Now, as shown in FIG. 2 (c), it is assumed that the light reception timing signal is defined by a phase different by 90 degrees in one cycle of the modulation signal. In this case, when the light reception outputs (charge amounts) corresponding to the respective light reception timing signals are A0, A1, A2, and A3, the phase difference ψ [rad] is expressed by the following equation.
ψ = (A0−A2) / (A1−A3)
If the frequency of the modulation signal is f [Hz], the time difference Δt from light projection to light reception is expressed as Δt = ψ / 2π · f using the phase difference ψ, so the speed of light is c [m / s]. Then, the distance to the object can be expressed as c · ψ / 4π · f.

  That is, the distance to the object can be obtained from the four types of light reception outputs (charge amounts) A0 to A3. The time width of the light receiving period can be set as appropriate so that an appropriate amount of received light can be obtained in the light receiving region (for example, a time width corresponding to a quarter period of the modulation signal can be used). ). However, the time width of each light receiving period needs to be equal to each other.

  In the arithmetic processing unit 7, in addition to the above-described processing for obtaining the phase difference ψ based on the received light output (charge amount) A0 to A3 and converting it to the distance, the processing described below can also be performed. The arithmetic processing unit 7 is configured using a computer, and the above-described processing is realized by executing a program on the computer. Further, not only the arithmetic processing unit 7 but also the configuration excluding the light emission source 1 and the image sensor 2 is realized using a computer.

  In the above-described operation example, four types of light reception timing signals are used. However, the phase difference ψ can be obtained using three types of light reception timing signals, and two types of light reception timing signals can be obtained in an environment where there is no ambient light or ambient light. It is possible to obtain the phase difference ψ even with the light reception timing signal.

  In the above-described operation, since one light receiving region is used for one pixel, four accumulation periods are required to extract four types of light receiving outputs (charge amounts) A0 to A3 from the image sensor 2. However, if two light receiving regions are provided for one pixel, it is possible to generate electric charges corresponding to two types of light receiving timing signals in one cycle of the modulation signal. The received light output corresponding to the signal can be read out once. Similarly, if four light receiving regions are provided in one pixel, charges corresponding to four types of light receiving timing signals are generated in one cycle of the modulation signal, and light receiving outputs corresponding to the four types of light receiving timing signals are generated once. It becomes possible to read by.

  Since the distance sensor A described above uses the imaging element 2 in which a plurality of pixels are two-dimensionally arranged as a light receiving element for receiving light from the target space, the distance value is obtained as the pixel value of each pixel. As a result, a distance image is generated. The generated distance image is stored in the memory of the computer.

  Below, the structure of the light projection optical system 3 and the light reception optical system 4 and the operation | movement of the arithmetic processing part 7 relevant to the structure of the light projection optical system 3 and the light reception optical system 4 are mainly demonstrated. The light projecting optical system 3 has a function of projecting the modulated light output from the light source 1 in a desired space in the target space.

  Here, as shown in FIG. 3, the light projecting optical system 3 includes a light branching device 3a using a half mirror that branches light output from one light source 1 into two paths, and a light branching device 3a. A slit light forming unit 3b that projects light in one path as slit light that spreads in a fan shape into a target space, and a lens that has a circular outer periphery for light in the other path branched by the light branching device 3a. It is formed by the spot light forming portion 3c that projects into the target space as spot light having a circular projection pattern.

  The slit light forming unit 3b uses a lens such as a cylindrical lens having a refractive power only in one plane to spread the incident light in a fan shape. A well-known thing can be used in the structure to project. In addition, since a light emitting device in which the light source 1 and the light projecting optical system 3 are integrated is provided on the market in order to project slit light, this type of light emitting device may be used.

  However, two light sources 1 are used without using the light branching device 3a, one light source 1 is associated with the slit light forming unit 3b, and the other light source 1 is associated with the spot light forming unit 3c. May be. Further, the slit light forming part 3b and the spot light forming part 3c can be formed using a mirror instead of a lens.

  Slit light is light whose light distribution is controlled to form a linear or strip-shaped light projection pattern on the surface of the object when it is projected onto the object, similar to light that passes through the slit. In a plane defined by the portion 3b and the longitudinal direction of the light projection pattern, it spreads in a fan shape, and the thickness in the direction orthogonal to the plane is substantially constant. On the other hand, the spot light has a conical light distribution with the spot light forming portion 3c as an apex, and forms a circular projection pattern on the surface of the object.

  The slit light and the spot light are projected into the field of the light receiving means formed by the light receiving optical system 4 and the image sensor 2. Therefore, a curtain-like monitoring region D1 using slit light and a conical monitoring region D2 using spot light are formed in the field of view of the light receiving means. The monitoring area D1 by the slit light is suitable for detecting the movement of an object from one of the two areas mainly divided by the monitoring area D1, and the monitoring area D2 by the spot light is mainly the monitoring area D2. Suitable for detecting objects present inside.

  As described above, by combining the two types of monitoring areas D1 and D2, two types of information can be acquired simultaneously. In the illustrated example, the monitoring areas D1 and D2 are set not to overlap, but the monitoring areas D1 and D2 may be set to partially overlap. Further, when the light source 1 is divided between the slit light forming unit 3b and the spot light forming unit 3c, the timing control unit 6 performs control so that the timing at which the modulated light is projected from each light source 1 is different. By doing so, it becomes possible to use the entire light receiving surface of the image sensor 2 for each of the monitoring areas D1 and D2. Even in the image sensor 2 having a small number of pixels (number of light receiving areas), the details of the monitoring areas D1 and D2 are detailed. It becomes possible to monitor.

  As described above, the modulated light is projected onto each of the plurality of monitoring areas D1 and D2 set within the field of view of the light receiving means, and the modulated light is not projected onto the area that does not require monitoring even within the field of view. Therefore, it is possible to suppress an increase in power required to drive the light source 1 while monitoring the state of the object by projecting light onto an area that needs to be monitored. In addition, while setting a plurality of monitoring areas D1 and D2, all the monitoring areas D1 and D2 are formed within the field of view of the light receiving means, so that only one image sensor 2 is required and the plurality of monitoring areas are configured with a simple configuration. D1 and D2 can be monitored, and cost increase can be suppressed. In addition, since the monitoring areas D1 and D2 are formed using optical elements such as lenses and mirrors that do not have a movable part, an object detection device that does not require a movable part and has high durability and reliability is provided. Can do.

  The setting example of the monitoring areas D1 and D2 described above is an example. For example, the light projecting unit is configured to project a plurality of slit lights, or the light projecting unit is configured to project a plurality of spot lights. It is also possible to do. In addition to the configuration in which slit light and spot light are combined and projected, the light projecting means may be configured to project only slit light or spot light to a plurality of monitoring areas. Furthermore, it is also possible to constitute a light projecting unit using a lens having an elliptical outer periphery in the light projecting optical system 3 so as to have an elliptical light projecting pattern.

  By the way, as described above, since the plurality of monitoring areas D1 and D2 are formed in the field of view of the light receiving means, useless areas not corresponding to the monitoring areas D1 and D2 are generated on the light receiving surface of the image sensor 2. . Therefore, if the light receiving optical system 4 is configured so that the images of the monitoring areas D1 and D2 are projected in accordance with the size of the light receiving surface of the image sensor 2, the light receiving surface of the image sensor 2 can be used without waste. It is. In particular, when a linear or belt-like projection pattern such as slit light or an elliptical projection pattern is formed, an area unrelated to the monitoring area is generated on the light receiving surface of the image sensor 2. .

  Now, assuming that the areas where the slit light and the spot light are projected are the monitoring areas D1 and D2, when a lens having a circular outer periphery is used for the light receiving optical system 4, as shown in FIG. On the light receiving surface, a linear image corresponding to the slit light and a circular image corresponding to the spot light are formed. In this configuration, images of the monitoring areas D1 and D2 are not formed in the most area of the light receiving surface of the image sensor 2. Therefore, most of the light receiving surface of the image sensor 2 is not used for monitoring objects in the monitoring areas D1 and D2.

  Therefore, as shown in FIG. 4A, a lens having an elliptical outer periphery is used for the light receiving optical system 4. The light receiving optical system 4 in the illustrated example has the aspect ratio of the images of the monitoring areas D1 and D2 so as to increase the magnification in the direction orthogonal to the extending direction of the projected pattern with respect to the extending direction of the projected pattern of slit light. (Ratio between the vertical direction and the horizontal direction of the image sensor 2) is adjusted.

  By adopting the light receiving optical system 4 of such an anamorphic optical system, the images of the monitoring areas D1 and D2 are extended in the vertical direction in the figure, and the images of the monitoring areas D1 and D2 are formed on the light receiving surface of the image sensor 2. Increases the share. Further, the area occupied by the monitoring areas D1 and D2 on the light receiving surface of the image pickup device 2 increases, and the number of pixels in the vertical direction corresponding to the monitoring areas D1 and D2 increases. Therefore, the resolution in this direction is improved. .

  Further, when the light receiving optical system 4 having an aspect ratio of 1: 1 as shown in FIG. 4B is used and the images of the monitoring areas D1 and D2 exceed the range of the light receiving surface of the image sensor 2, By adopting the light receiving optical system 4 of the anamorphic optical system, the image can be reduced and accommodated within the width of the light receiving surface of the image sensor 2.

  In other words, the monitoring area D1 is reduced so that the image of the monitoring area D1 is long enough to fit on the light receiving surface of the image sensor 2 in the one direction, and the light receiving surface of the image sensor 2 can be used effectively in the other direction. , D2 so as to enlarge the image, the anamorphic optical system is adopted as the light receiving optical system 4 and the aspect ratio of the monitoring areas D1 and D2 is adjusted so that the light receiving surface of the image sensor 2 can be effectively used. .

  By the way, even if only the anamorphic optical system is adopted as the light receiving optical system 4, the light receiving surface of the image pickup device 2 is used more effectively than when the aspect ratio of the light receiving optical system 4 is 1: 1. In order to more effectively use the two light receiving surfaces, a light receiving optical system 4 in which a plurality of optical elements are combined may be employed.

  For example, using a lens as an optical element, as shown in FIG. 5A, two lenses 4a and 4b are juxtaposed, one lens 4a is associated with the monitoring area D1, and the other lens 4b is monitored. Correspond to D2. The lenses 4a and 4b are designed so as to form images of the monitoring areas D1 and D2 at different parts of the light receiving surface of the image sensor 2, respectively.

  If this configuration is adopted, the lenses 4a and 4b can be designed for each of the monitoring areas D1 and D2. Therefore, as shown in FIG. 5B, the area A1 that associates the light receiving surface of the image sensor 2 with the monitoring area D1. The lenses 4a and 4b are designed so that the images of the monitoring areas D1 and D2 are formed in the areas A1 and A2 of the light receiving surface. For example, the image of the monitoring area D1 is reduced in the extension direction and enlarged in the direction orthogonal to the extension direction, and the image of the monitoring area D2 is deformed into an ellipse so as to occupy most of the area A2.

  As described above, the lenses 4a and 4b are designed for each of the monitoring areas D1 and D2 (in the above example, the anamorphic optical system is designed so that the aspect ratios are different from each other) and the images of the two monitoring areas D1 and D2 are used. Are formed in different areas A1 and A2 of the light receiving surface of the image sensor 2, so that most of the pixels on the light receiving surface of the image sensor 2 can be associated with the monitoring areas D1 and D2, and monitoring is a part of the target space. Although the modulated light is projected only in the regions D1 and D2, the light receiving surface of the image sensor 2 can be used effectively.

  Then, by utilizing most of the pixels provided on the light receiving surface of the image sensor 2, a part of the monitoring areas D1 and D2 is enlarged and monitored in detail, and the other part is reduced and reduced. Can be monitored. Further, by adopting the configuration of FIG. 5, it is possible to monitor a plurality of monitoring areas D <b> 1 and D <b> 2 using one image sensor 2.

  As the light receiving optical system 4 combining a plurality of optical elements, a configuration combining a low resolution optical element and a high resolution optical element may be employed. Depending on the design of the optical element, it is possible to monitor the presence or absence of an object in the low-resolution region and to monitor details such as the shape of the object in the high-resolution region. In the above example, when the passage of the object is detected in the monitoring area D1 corresponding to the slit light, the monitoring area D1 may have a low resolution, and when the shape of the object is measured in the monitoring area D2 corresponding to the spot light. It is desirable that the monitoring area D2 has a high resolution.

  Further, as a configuration in which a plurality of optical elements are combined, as shown in FIG. 6A, an image obtained by enlarging the central portion of the monitoring region D1 formed by the slit light as compared with the configuration shown in FIG. You may employ | adopt the structure which added the lens 4c formed in the light-receiving surface of the element 2. FIG. In the illustrated example, the center of the light receiving surface of the image sensor 2 is associated with the lens 4c. That is, a narrow-angle region is formed in the center of the field of the light receiving unit, a wide-angle region is formed on one side of the region in the field of the light receiving unit, and the light beam is formed by spot light on the other side in the field of view. An area corresponding to the monitoring area D2 is formed.

  In this configuration, when a lens is used as an optical element, as shown in FIG. 6A, a light receiving optical system 4 in which lenses 4a and 4c having different viewing angles are arranged side by side with a lens 4b for the monitoring region D2 is used. The illustrated light receiving optical system 4 includes three lenses 4a, 4b, and 4c arranged one above the other so that the field of view by the lens 4c disposed at the center is a narrow angle and the field of view by the lens 4a disposed at the bottom is a wide angle. It is as. Further, the lens 4b arranged at the upper part is formed so that the entire monitoring region D2 corresponding to the spot light is in the field of view, similarly to the lens 4b shown in FIG.

  When such a light receiving optical system 4 is used, as shown in FIG. 6B, in a region A2 above the light receiving surface of the image sensor 2, a monitoring region D2 where the spot light is projected can be monitored, and imaging is performed. The entire monitoring area D1 where the slit light is projected can be monitored in the area A1 below the element 2, and further, the slit light is projected in the area A1 ′ at the center of the light receiving surface of the imaging element 2. It becomes possible to monitor a monitoring area D1 ′ obtained by enlarging a part of the monitoring area D1. Therefore, if the central area A1 ′ and the lower area A1 of the light receiving surface of the image sensor 2 are respectively associated with the monitoring areas D1 ′ and D1 where the slit light is projected, the monitoring where the slit light is projected is performed. With respect to the region D1, it is possible to monitor the whole and details.

  Also in the case of using the light receiving optical system 4 in which a plurality of optical elements are combined, a plurality of light emitting sources 1 that project light is provided for each of the monitoring regions D1 and D2, and modulated light is output for each light emitting source 1 by the timing control unit 6. The timing may be controlled. In this configuration, since it is possible to project light for each of the monitoring areas D1 and D2, it is possible to reduce the power required for light projection compared to the case where light is simultaneously projected to the plurality of monitoring areas D1 and D2.

  The object detection device configured as described above includes, for example, a sensor for confirming safety when the door is running in a door (elevator door, train door, entrance door, etc.) that is driven by a drive source. It can be applied to a sensor for monitoring on-site entry in a factory.

  For example, when the above-described object detection device is applied to an elevator door, as shown in FIG. 7, the distance sensor A along the upper edge of the opening 12 serving as an entrance provided in the car 11 of the elevator 10. Place.

  In the door 13 that opens and closes the opening 12 of the elevator 10, when a person's hand or belongings touch the door 13 when the opening operation is started from the closed state, the door 13 is stored in the sleeve of the opening 12. In addition, since there is a possibility that hands and belongings are drawn into the sleeve of the opening 12, it is necessary to monitor the part of the opening 12 where the door 13 enters and exits (monitoring area E1).

  Further, when the door 13 is performing the closing operation, there is a possibility that hands or belongings may be pinched by the door 13, so it is also necessary to monitor the vicinity of the front end of the door 13 (monitoring area E2).

  Furthermore, when the door 13 starts to close when a person gets in from the hall outside the car 11 when the door 13 is in the open state, the person collides with the door 13, so that the person goes from the hall to the car 11. It is also necessary to monitor the moving person (monitoring area E3).

  Therefore, the light receiving unit projects light individually from the monitoring areas E1 to E3, and the light receiving unit projects each monitoring area E1 to E3 onto a region defined on the light receiving surface of the image sensor 2. 4 is preferably formed of a plurality of optical elements. The monitoring areas E1 and E3 can be handled by spot light, and the monitoring area E2 can be handled by slit light. Moreover, the monitoring area | region E3 should just set toward the outer side of the cage | basket | car 11, and should just detect the person who tries to get into the cage | basket | car 11 while the door 13 changes from an open state to a closed state.

  As can be seen from the above-described operation, when monitoring the door 13 of the elevator is performed, the monitoring regions E1 to E3 may be set in conjunction with the operation of the door 13, so that the modulated light to the monitoring regions E1 to E3 is set. There is no need to continuously perform light projection, and power consumption can be further reduced. In addition, use to an elevator is an example, and as described above, the object detection device of the present invention can be used for various applications.

1 Light source (light projection means)
2 Image sensor (light receiving means)
3. Projection optical system (projection means)
3b Slit light forming part 3c Spot light forming part 4 Light receiving optical system (light receiving means)
4a to 4d lens (optical element)
5 Modulation signal generation unit 6 Timing control unit 7 Arithmetic processing unit 8 Object detection unit

Claims (6)

A light source that outputs modulated light whose intensity changes over time, and a light projecting means that projects the modulated light output from the light source onto a desired region of the target space, and a two-dimensional array An image sensor that has a plurality of light receiving areas, and that can output an output corresponding to the intensity of received light for each light receiving area, and a light receiving optical system that defines a field of view and makes light from within the field incident on the image sensor. The distance to the object for each light receiving region is obtained and obtained from the time difference between the light receiving means and the light emitting source outputting the modulated light and the reflected light of the modulated light from the object existing in the target space being received by the image sensor. comprising distance arithmetic processing unit for generating a distance image and pixel values, and a object detection section for detecting an object in the target space from the distance image calculation processing unit has generated, the light projecting means is defined by a light receiving optical system It has been received And a slit light forming unit and the spot light forming unit respectively for projecting light and a slit beam and the spot light in the field of view of the unit, respectively for projecting the modulated light to the monitoring area set by the slit light and the spot light An object detection device characterized by that. 2. The anamorphic optical system that adjusts an aspect ratio of the image so that an image of each monitoring area is projected in accordance with a size of a light receiving surface of the image sensor. Object detection device. 3. The object detection apparatus according to claim 1, wherein the light receiving optical system includes a plurality of optical elements that respectively project images of the respective monitoring areas onto different portions of the light receiving surface of the image sensor. 2. The light receiving optical system is formed by combining a plurality of optical elements having different resolving power so as to form a low resolving power region and a high resolving power region in the field of view of the light receiving means. The object detection apparatus of any one of -3. 2. The light receiving optical system is formed by combining a plurality of optical elements having different viewing angles so as to form a narrow-angle region and a wide-angle region in the field of view of the light-receiving means. The object detection apparatus of any one of -3. The light projecting unit includes a plurality of light emitting sources associated with each monitoring region, and a timing control unit for controlling timing of outputting modulated light for each light emitting source is added . object detection equipment according to any one of 5.

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