JP2014224726A - Optical distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-precision optical distance measuring device capable of easily correcting a signal (noise) reflected by a protective cover and detected by a light receiving element, without requiring a special measurement environment, when the protective cover is provided in front of the distance measuring device.SOLUTION: In an optical distance measuring device, a correction operation part computes a correction coefficient corresponding to the intensity distribution of cover reflected light from intensity distributions SA, SB of partial regions 8a, 8b at least on one side of both ends of a light receiving element, and corrects the intensity distribution S0 of spot light, and a distance computing part computes the distance to a measuring object based on the output from the correction operation part.

Description

  The present invention relates to an optical distance measuring device that optically detects a distance to an object to be measured and an electronic device equipped with the same, and particularly when a protective cover is installed on the front surface of the optical distance measuring device. The present invention relates to an optical distance measuring device that prevents a decrease in distance measuring accuracy by correcting reflected light reflected by a cover and detected by a light receiving element.

  Conventionally, as shown in FIG. 101, many distance measuring apparatuses 150 for irradiating a measurement object 110 with spot light, receiving the reflected light, and measuring the distance to the measurement object 110 by triangulation have been proposed. Yes. The light beam emitted from the light emitting element 101 arranged at the point A (0, −d) becomes a substantially parallel light beam by the light emitting lens 102 arranged at the origin O (0, 0), and becomes a point B (0 on the measurement object). , Y) is irradiated with a light spot. The light beam reflected by the measurement object 110 is collected by the light receiving lens 103 disposed at the point C (L, 0) and is connected to the point D (L + l, -d) on the light receiving element 104 disposed on the x axis. It is imaged to form a light receiving spot. The light emission axis A100 indicates a straight line passing through the origin O (0, 0), the point B (0, Y), and the point C (L, 0). The light receiving axis A101 indicates a straight line passing through the point B (0, Y), the point C (L, 0), and the point D (L + l, -d). Here, when the point E (L, -D) is a point where a line parallel to the y-axis passing through the point C intersects the x-axis, the triangle OBC and the triangle ECD are similar. By detecting the position of the light receiving spot by the light receiving element 104 and measuring the side ED (= l), the distance Y to the measurement object 110 can be detected based on the equation (1).

  This is the general principle of triangulation. As the light receiving element, a PSD (position detecting element), a linear sensor in which a plurality of PDs are arranged, an image sensor, or the like is used. The light receiving element detects the light barycenter position of the light receiving spot irradiated on the light receiving element.

  When the optical distance measuring device 150 operating on such a principle is used, a protective cover 120 having a sufficiently high transmittance for the light beam emitted from the light emitting element is installed on the front surface thereof as shown in FIG. Is done. Most of the emitted light beam F0 adjusted to substantially parallel light through the light emitting lens 103 passes through the protective cover 120 having a high transmittance and irradiates the measurement object 110. The reflected light F 1 passes through the protective cover 120 again and enters the light receiving element 104 through the light receiving lens 103. As a result, the light spot position corresponding to the distance Y to the measurement object 110 is detected. However, a part of the luminous flux F0 is reflected by the surface of the protective cover 120 and becomes cover reflected light F2. The cover reflected light F <b> 2 enters the light receiving lens 103 while being directly or sneak around and is detected by the light receiving element 104. When the protective cover 120 is installed on the front surface of the distance measuring device 150 in this way, in addition to the light spot collected on the light receiving element 104 by the reflected light F1 reflected by the measurement object 110, the protective cover 120 is used. The reflected light is detected by the light receiving element 104. As a result, there is a problem that the distance Y to the measurement object 110 cannot be measured accurately.

  In response to such a problem, Patent Document 1 discloses that when a window glass is installed on the front surface of the distance measuring device, the measured distance is measured even though the amount of received light signal is smaller than a predetermined amount of received light. If is a short distance, it is considered that the distance measurement is wrong and the output is corrected to infinity or switched to passive distance measurement.

  Further, in Patent Document 2, the light reflected by the protective cover is a sneak path light, and is only irradiated uniformly on the light receiving element without being condensed on the light receiving element. In consideration of the fact that only the light intensity information with uniform intensity is present, it has been proposed to perform distance calculation by subtracting the light intensity reflected from the protective cover from the received light signal. Here, the amount of light reflected from the protective cover is obtained in advance by detecting a signal only from the protective cover by performing a distance measuring operation at infinity, and is stored in the memory.

  However, when the reflected light from the protective cover has an intensity distribution on the light receiving element, Patent Document 1 and Patent Document 2 cannot perform accurate distance measurement. For this reason, in the patent document 3, the present inventors memorize | stored the intensity distribution which reflected light from a protective cover produces on a light receiving element in a memory, and calculated intensity distribution of cover reflected light from a received light spot signal in the case of distance calculation. It has been proposed to subtract and detect the distance to the measurement object based on the received light spot signal after subtraction. Furthermore, the present inventors approximate (numerize) the intensity distribution of the reflected light of the protective cover in order to reduce the amount of memory mounted, and correct the light reception spot using the intensity distribution obtained from the approximate expression. Has also proposed. In addition, the method for obtaining the intensity distribution of the two parties needs to detect the light reception signal of only the reflected light from the protective cover in the state of infinity, as in Patent Document 2.

JP-A-9-229671 JP 2000-314835 A JP 2011-117940 A

  However, since the optical distance measuring devices of Patent Document 1 and Patent Document 2 are used with the received light intensity detected by the light receiving element, they are limited only when the reflected light from the protective cover is distributed with a uniform intensity on the light receiving element. It is done. Furthermore, Patent Document 1 performs a process of correcting the output to infinity or switching to passive distance measurement when the amount of reflected light received by the protective cover is large, and when the active type distance measuring device has a protective cover alone. High accuracy cannot measure distance. In Patent Documents 2 and 3, the amount of light reflected by the protective cover and the intensity distribution of the reflected light by the protective cover are stored in a memory, and the stored information is subtracted from the received light signal, thereby providing a protective cover on the front surface of the distance measuring device. This is a technology that can measure the distance with high accuracy even when Both technologies require a step of measuring the information to be subtracted (the amount of reflected light and the intensity distribution of the reflected light) in an environment where the light that has passed through the protective cover in advance is not incident on the light receiving part and stored in the memory. And For this reason, Patent Documents 2 and 3 have a problem in terms of ease of use of the distance measuring device.

  The present invention has been made in view of the above problems, and when a protective cover is installed on the front surface of the distance measuring device, it is easily reflected by the protective cover without requiring a special measurement environment. It is an object of the present invention to provide a highly accurate optical distance measuring device that can correct a detected signal (noise).

  The optical distance measuring device of the present invention includes a light emitting element, a light emitting optical system that focuses a light beam emitted from the light emitting element, and irradiates a measuring object with spot light, and a reflected light from the measuring object. A light receiving optical system for condensing, a light receiving element for detecting spot light from the measurement object collected by the light receiving optical system, and a signal processing unit for processing a light reception signal from the light receiving element, The light receiving element is a line sensor or an area sensor that detects an intensity distribution of reflected light from the measurement object, and the signal processing unit is configured to spot the spot light collected by the light receiving optical system on the light receiving element. A distance calculating unit that calculates a position and detects a distance from the spot position to the measurement target, the light emitting optical system, the light receiving optical system, and a translucent element disposed between the measurement target. Protective cover And a correction calculation unit that corrects the calculation of the distance by detecting the intensity distribution of the cover reflected light detected by the light receiving element via the light receiving optical system, and the correction calculation unit includes: The correction coefficient corresponding to the intensity distribution of the cover reflected light is calculated from the intensity distribution of at least one partial region at both ends of the light receiving element, the intensity distribution of the spot light is corrected, and the output of the correction calculation unit Based on the above, the distance calculation unit calculates the distance to the measurement object.

  In one embodiment, the correction calculation unit calculates the correction coefficient by linearly approximating the intensity distribution of the cover reflected light from the intensity distribution of the partial area at both ends of the light receiving element. It is characterized by.

  In the distance measuring apparatus according to an embodiment, the correction calculation unit performs linear approximation by a least square method using intensity distributions of the partial regions at both ends of the light receiving element.

  Further, in the distance measuring apparatus according to one embodiment, the correction calculation unit uses the intensity distribution of the partial area at both ends of the light receiving element to calculate the average value of the intensity distribution at one end and the average value of the intensity distribution at the other end. A linear approximation is performed from the above.

  Further, in the distance measuring apparatus according to an embodiment, the correction calculation unit performs linear approximation by least square method for the intensity distribution of the partial region at both ends of the light receiving element, and a difference in inclination between the both ends is determined in advance. If the correlation coefficient at one end of the light receiving element is greater than a predetermined threshold, the correction coefficient is calculated with the intensity distribution at the other end. Is calculated.

  The optical distance measuring device of the present invention detects the intensity distribution of the spot light reflected from both the measurement object and the protective cover and detected by the light receiving element, and corrects the correction coefficient from the intensity distribution of at least one end of the light receiving element. Is calculated to correct the intensity distribution due to the reflection of the protective cover. Therefore, the distance measuring device can perform information necessary for correcting the reflected light of the protective cover while measuring the distance to the measurement object, and stores the information in a memory in a special measurement environment such as infinity. There is no need to remember. Therefore, the distance measuring device can easily measure the distance to the measurement object. Further, since the distance measuring device does not require a memory for storing the information of the reflected light of the protective cover to be corrected, the signal processing circuit (signal processing unit) can be reduced in scale, and the step of storing the information in advance is also possible. do not need. For this reason, an inexpensive optical distance measuring device can be provided.

It is a figure explaining a mode that the reflected light of a measuring object and a protective cover injects into a light receiving element. It is a figure which shows intensity distribution detected with a light receiving element by both the reflected light of a measurement object and a protective cover. It is a figure which shows intensity distribution of the reflected light of a protective cover only, and its linear approximation. It is the intensity distribution calculation result by the reflected light of only the measuring object obtained by subtracting FIG. 3 from FIG. It is a figure which shows the dispersion | variation in the correction coefficient by an optical distance measuring device and its assembly | attachment dispersion | variation. It is a figure which shows the block diagram of the optical distance measuring device of this invention. It is a figure which shows the correction method of the protective cover reflected light of the optical distance measuring device of this invention. It is a figure explaining the correction method of Example 1 of the optical distance measuring device of the present invention. It is a figure explaining the correction method of Example 2 of the optical distance measuring device of this invention. It is a figure explaining the correction malfunction of Example 1 of the optical distance measuring device of the present invention. It is a figure explaining the method of avoiding the correction malfunction of Example 3 of the optical ranging apparatus of this invention. It is a figure explaining the method of avoiding the correction malfunction of Example 3 of the optical ranging apparatus of this invention. It is a figure explaining the optimal light-receiving area | region of the optical distance measuring device of this invention. It is a figure which shows an example of the electronic device carrying the optical distance measuring device of this invention. It is a figure which shows the principle of an optical distance measuring device. It is a figure explaining the reflected light of the state by which the protective cover was installed in the optical distance measuring device.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 illustrates how reflected light from the measurement object 10 and reflected light from the protective cover 20 enter the light receiving element 4 with the protective cover 20 installed on the front surface of the optical distance measuring device 50. It is a figure to do. The broken line indicates the reflected optical axis A1 from the measurement object 10, and the solid line indicates the reflected optical axis A2 from the protective cover 20. Here, the reflected optical axis from the protective cover 20 actually draws a complicated locus due to multiple reflection (scattering) inside the protective cover 20 and the distance measuring device 50. The illustrated reflected optical axis A1 represents the optical axis detected by the light receiving element 4 as a result of multiple reflection.

  The distance measuring device 50 includes a light emitting element 1, a light emitting lens 2, a light receiving lens 3, and a light receiving element 4. The light emitted from the light emitting element 1 is emitted as substantially parallel light by the light emitting lens 2. The protective cover 20 disposed near the distance measuring device 50 has a sufficiently high transmittance with respect to the wavelength of the luminous flux. While most of the emitted light beam irradiates the measurement object 10, it is slightly reflected on both surfaces 20a and 20b of the protective cover 20. Reflected light from the measurement object 10 at a sufficiently distant position passes through the protective cover 20 and is collected by the light receiving lens 3 to form a light spot on the light receiving element 4. The light reflected by the protective cover 20 is collected by the light receiving lens 3 and travels toward the light receiving element 4 with a very large incident angle. The light receiving area 8 of the light receiving element 4 has a size necessary for detecting the intensity distribution S10 (FIGS. 4 and 13) of the measurement object 10. On the other hand, as shown in FIG. 1, the reflected light from the protective cover 20 is detected only at the skirt on the left side of the light spot S. For easy understanding, FIG. 1 shows a diagram in which a light spot S is formed on the right outer side of the distance measuring device 50 without the right side wall of the distance measuring device 50. Actually, since the inside of the side wall of the distance measuring device 50 is formed of a resin having a sufficiently low reflectance, the amount of scattered light detected by the light receiving element 4 is extremely small. That is, the influence of scattered light can be ignored. For this reason, the intensity distribution of the reflected light by the protective cover 20 is equivalent to that shown in FIG.

  FIG. 2 shows the intensity distribution (reflected light profile) S0 of the light spot detected by the light receiving element 4 in such a state. The x-axis in FIG. 2 is the coordinates of the light receiving element 4, and is the same direction as the direction in which the light emitting element 1 and the light receiving element 4 are arranged in FIG. The pixel coordinate of the image sensor is described in the x-axis item. The light receiving element 4 is not limited to an image sensor having a two-dimensional pixel, and there is no problem even if it is a line sensor in which a plurality of pixels are arranged only on the x axis. Hereinafter, this description is omitted. The y-axis represents the light intensity incident on each pixel, and corresponds to the received light intensity detected by the light receiving element 4. As shown in FIG. 2, the intensity distribution S0 of both the reflected light F1 of the measurement object 10 and the reflected light from the protective cover 20 (cover reflected light F2) is a cover reflected light having a uniform right-up shape. The intensity distribution S20 of F2 is added to the intensity distribution S10 (FIG. 4) of the measurement object 10 having a Gaussian shape. Here, the uniform right-upward intensity distribution S20 due to the reflected light of the protective cover 20 indicates the skirt of the light spot S as described in FIG. When the light spot position (center of gravity) is obtained from such an intensity distribution S0, the intensity distribution S20 that rises to the right due to the reflected light of the protective cover 20 is added, so the light spot position is the intensity distribution S10 of the measurement object 10. Will be detected by shifting to the right side (+ x side) from the center of gravity position. Therefore, the distance measurement accuracy is reduced by an amount corresponding to the shift amount.

  The present inventors have proposed a method for reducing the influence of reflection of the protective cover in Patent Document 3, and this method will be briefly described. FIG. 3 is a diagram showing the intensity distribution S20 of only the protective cover 20 and a linear approximation thereof. If the slope k of this linear approximation is a correction coefficient, this correction coefficient corresponds to the intensity distribution S20 of the protective cover 20. The correction coefficient is measured in advance in the absence of the measurement object 10 (infinite edge), and the intensity distribution S20 of the protective cover 20 that is linearly approximated is subtracted from the intensity distribution S0 in FIG. An intensity distribution S10 of the reflected light F1 of the measurement object 10 is obtained. For this reason, the method of patent document 3 can prevent the fall of ranging accuracy. In the manufacturing process of the optical distance measuring device, the positional relationship among the light emitting element, the light receiving element, the light emitting lens, and the light receiving element includes some variation. Further, the positional relationship between the optical distance measuring device and the protective cover, for example, the distance to the cover and the inclination of the cover also includes variations. For this reason, as shown in FIG. 5, the correction coefficient actually has individual variations. When correction is performed using a fixed value: k, the distance measurement accuracy decreases by an amount corresponding to the variation of the correction coefficient. In order to set the correction coefficient for each distance measuring device 50, it takes time for the measurement, and a memory for storing it is required.

  FIG. 6 is a block diagram illustrating the configuration of the embodiment 1-3 of the present invention. The distance measuring device 50 includes a signal processing unit 5 that processes a light reception signal from the light receiving element 4. The signal processing unit 5 includes a correction calculation unit 6 and a distance calculation unit 7. The luminous flux F0 emitted from the light emitting element 1 is reflected by the measurement object 10 and the protective cover 20, respectively, and becomes reflected light F1 of the measurement object 10 and reflected light from the protective cover 20 (cover reflected light F2). The light F1 and the cover reflected light F2 enter the light receiving element 4. The intensity distribution S0 detected by the light receiving element 4 is corrected to the intensity distribution S10 of the measurement object 10 after the correction coefficient is obtained by the correction calculation unit 6 of the signal processing unit 5. The light spot position is calculated from the corrected intensity distribution S10, and the distance Y from the origin (position of the light emitting lens 2) to the measurement object 10 is detected. Here, the memory for storing the correction coefficient mounted in the signal processing unit of Patent Document 3 is not mounted in this embodiment. FIG. 7 shows an intensity distribution detected by the light receiving element 4 with the configuration of FIG. A part 8a and B part 8b show two partial regions at both ends of the light receiving element 4 (light receiving area 8). The A portion 8a is a partial region of the light receiving element 4 on the light emitting element 1 side having a small x-axis value, and the B portion 8b is a partial region of the light receiving element 4 on the side having a large x-axis value. Since the reflected light F1 of the measurement object 10 hardly enters the A part 8a and the B part 8b, the cover reflected light F2 becomes dominant in the intensity distribution of the A part 8a and the B part 8b. Using the intensity distributions SA and SB of the A portion 8a and the B portion 8b, the correction calculation unit 6 obtains a correction coefficient corresponding to the intensity distribution of the cover reflected light F2. By correcting the intensity distribution S0 including the intensity distribution S20 of the protective cover 20 based on this correction coefficient, the intensity distribution S10 of the reflected light F1 of the measurement object 10 is obtained. The distance calculation unit 7 calculates the light spot position and calculates the distance Y to the measurement object while always detecting and correcting the cover reflected light F2 in real time based on the output (correction coefficient) of the correction calculation unit 6. To do. For this reason, the distance measuring device 50 does not require a memory for storing the correction coefficient, and can perform distance measurement corresponding to variations among products and assembly variations of the protective cover 20.

  FIG. 8 is a diagram for explaining an optimal calculation method of the correction coefficient according to the first embodiment. Solid lines (thin lines) indicate the intensity distributions SA and SB of the cover reflected light F2 of the A part 8a and the B part 8b, and broken lines indicate the intensity distributions S0 of the measurement object 10 and the protective cover 20. Solid lines (thick lines) use the intensity distributions SA and SB of the A part 8a at one end of the light receiving element 4 and the B part 8b at the other end, excluding the intensity distribution in the central part between the A part 8a and the B part 8b. The straight line C1 which performed the linear approximation is shown. The correction coefficient is given as the slope of this straight line C1. By this method, the intensity distribution S20 of the reflected light F2 from the protective cover 20 can be accurately approximated. Further, in the linear approximation, it is preferable to use the least square method by using the intensity distributions SA and SB of the A part 8a and the B part 8b from the viewpoint of accuracy of approximation.

  FIG. 9 is a diagram illustrating a correction coefficient calculation method according to the second embodiment. It is also possible to obtain a correction coefficient from a straight line C2 connecting the AB points, where the average point of the total intensity distribution SA of the A portion 8a is A point Pa and the average point of the total intensity distribution of the B portion 8b is B point Pb. In this case, since the calculation can be simplified as compared with the above least square method, the circuit scale of the correction calculation unit 6 can be reduced.

When the least square method is used for the linear approximation, it is possible to verify whether there is a defect in the correction calculation, and if there is a defect, the distance output can be adjusted by error determination. FIG. 10 is a diagram illustrating an intensity distribution S0 obtained by combining the reflected light F1 and the cover reflected light F2 of the measurement object 10 when the protective cover 20 is disposed at a distance away from the distance measuring device 50. The intensity distribution S0 in FIG. 10 has a shape in which the right end of the B portion 8b is raised. This is because the protective cover 20 is disposed at a position away from the distance measuring device 50. As the protective cover 20 moves away, the incident angle of the cover reflected light F2 decreases. Along with this, the light receiving spot (range of intensity distribution S0) due to the reflection of the protective cover 20 shown in FIG. 1 is relatively shifted to the left side, and the right end of the B portion 8b is lifted. In addition, when the thickness of the protective cover 20 is large, the incident angle of the cover reflected light F2 is similarly reduced, so that the right end of the B portion 8b is similarly lifted. In such a case, as indicated by the solid line (thick line) in FIG. 10, the straight line C2 detected by the least square method does not reflect the actual intensity distribution, and is a straight line that should be approximated by the original straight line indicated by the broken line. Deviation occurs from C21. A distance measurement value detected from such a correction state may include a large error. Therefore, the minimum time correlation coefficient R ² obtained by the calculation of squares is less than or equal to the threshold which is determined in advance, fixed to the error signal output of the distance measurement value as a correction failure state (for example, the maximum value of the distance output value) By doing so, it is possible to prevent a decrease in distance measurement accuracy.

11 and 12 are diagrams for explaining a correction coefficient calculation method according to the third embodiment. FIG. 11 is a diagram illustrating a case where the intensity distribution SB of the B portion 8b is not uniform. FIG. 12 is a diagram showing an intensity distribution when the measurement object 10 is at a close distance. The intensity distribution S0 in FIG. 11 may be obtained, for example, when there are regions with different reflectivities on the measurement object 10. As shown in FIG. 12, when the measurement object 10 is at a close distance of the distance measuring device 50, the incident angle of the reflected light F1 becomes large, so that the right hem of the light spot S enters the B portion 8b. It becomes like this. In both FIGS. 11 and 12, the slope k (A) of the linear approximation of the intensity distribution SA of only the A portion 8a is different from the slope k (B) of the linear approximation of the intensity distribution SA of only the B portion 8b. In such a case, if the correction coefficient is calculated using both the A portion 8a and the B portion 8b, the error of the distance measurement value increases. By performing linear approximation in each of the A portion 8a and the B portion 8b, the slopes k (A) and k (B) of the A portion 8a and the B portion 8b are obtained. In order to prevent a decrease in distance measurement accuracy, the following correction is performed. When the difference between the slopes k (A) and k (B) of the A portion 8a and the B portion 8b is equal to or greater than a predetermined threshold value, correction is executed with the slope of the straight line CA of only the A portion 8a. When the correlation coefficients R ² (A) and R ² (B) of the A part 8a and the B part 8b are calculated and the correlation coefficient at one end (for example, the A part 8a) is equal to or greater than a predetermined threshold, Correction is executed using the linear approximation slope of the other end (for example, the B portion 8b). Naturally, the calculation may be performed using both the slope and the correlation coefficient.

  FIG. 13 is a diagram for explaining the size of the light receiving element 4 in each correction method described in the first to third embodiments. FIG. 13 shows intensity distributions S10S and S10L of the reflected light F1 of the measurement object 10 at the minimum value and the maximum value of the distance measurement range of the optical distance measuring device 50. The intensity distribution S10L in the white area is the reflected light from the measurement object 10 having the maximum value in the distance measurement range. The intensity distribution S10S in the hatching area is reflected light from the measurement object 10 having the minimum value in the distance measurement range. As shown in FIG. 13, the width of the light receiving area 4a of the light receiving element 4 has a sufficient area to be the A portion 8a at the left end of the intensity distribution S10L formed by the measurement object 10 having the maximum value in the distance measuring range. It is preferable that there is a sufficient area to be the B portion 8b at the right end from the intensity distribution S10S formed by the measurement object 10 having the minimum value. By securing these areas sufficiently, the distance calculation can be corrected with high accuracy.

  FIG. 14 is a diagram showing a personal computer 200 on which the distance measuring device 50 is mounted. The personal computer (electronic device) 200 is equipped with a correction function for correcting the cover reflected light F2 in real time, and can be corrected including individual variations. For this reason, the personal computer 200 can accurately detect whether or not the person 300 is present in front of the personal computer 200, and can put the personal computer 200 in the sleep mode when the person 300 disappears. This makes it possible to save energy efficiently. Further, if the optical distance measuring device 50 is mounted on a self-propelled cleaner, obstacles and steps can be detected. If the optical distance measuring device 50 is mounted on a kitchen appliance, it can be used as a non-contact switch that turns the operation on and off in a non-contact manner. In addition, the optical distance measuring device 50 is suitable for the operation of electronic devices such as detecting the distance to the hand and performing various volume controls such as an amusement device.

  The optical distance measuring device 50 according to the present invention includes a light emitting element 1, a light emitting optical system (light emitting lens 2) that focuses a light beam emitted from the light emitting element 1 and irradiates spot light on the measurement target 10. A light receiving optical system (light receiving lens 3) that collects reflected light from the measurement object 10, a light receiving element 4 that detects spot light from the measurement object 10 collected by the light receiving optical system, and the above A signal processing unit 5 that processes a light reception signal from the light receiving element 4, and the light receiving element 4 is a line sensor or an area sensor that detects an intensity distribution S0 of reflected light from the measurement object 10, and the signal The processing unit calculates a spot position on the light receiving element 4 of the spot light collected by the light receiving optical system, and detects a distance Y from the spot position to the measurement object 10; , Above luminescence Cover in which the light reflected by the translucent protective cover 20 disposed between the optical system and the light receiving optical system and the measurement object 10 is detected by the light receiving element 4 through the light receiving optical system. A correction calculation unit 6 that detects the intensity distribution of the reflected light F2 and corrects the calculation of the distance Y. The correction calculation unit 6 is an intensity distribution of at least one partial region at both ends of the light receiving element 4. A correction coefficient corresponding to the intensity distribution S20 of the cover reflected light F2 is calculated from SA (SB) to correct the intensity distribution S0 of the spot light, and the distance calculation unit 7 is based on the output of the correction calculation unit 6. Calculates the distance Y to the measurement object 10.

  The optical distance measuring device 50 configured as described above detects the intensity distribution S0 of the spot light reflected from both the measurement object 10 and the protective cover 20 and detected by the light receiving element 4, and at least one end of the light receiving element 4. The correction coefficient is calculated from the intensity distribution SA (SB) of the above, and the intensity distribution S20 due to the reflection of the protective cover 20 is corrected. Therefore, the distance measuring device 50 can perform information necessary for correcting the cover reflected light F2 while measuring the distance to the measurement object 10, and stores the information in a special measurement environment such as infinity. There is no need to memorize. For this reason, the distance measuring apparatus 50 can easily measure the distance to the measurement object 10. Further, since the distance measuring device 50 does not require a memory for storing information of the cover reflected light F2 to be corrected, the signal processing circuit (signal processing unit 5) can be reduced in scale and the information is stored in advance. It is not necessary. Therefore, an inexpensive optical distance measuring device 50 can be provided.

  In the distance measuring device 50 according to an embodiment, the correction calculation unit 6 linearly approximates the intensity distribution of the cover reflected light from the intensity distribution of the partial area at both ends of the light receiving element 4 to obtain the correction coefficient. It is characterized by calculating.

  The optical distance measuring device 50 having the above configuration calculates a correction coefficient by linearly approximating the intensity distribution S20 of the cover reflected light F2 from the intensity distributions SA and SB of the partial areas 8a and 8b at both ends of the light receiving element 4. For this reason, the intensity distribution S20 of the cover reflected light F2 can be accurately approximated without separating the reflected light F1 and the cover reflected light F2 of the measurement object 10. For this reason, the distance measuring device 50 can easily correct the cover reflected light F2.

  In the distance measuring device 50 according to an embodiment, the correction calculation unit 6 performs linear approximation by the least square method using the intensity distributions SA and SB of the partial regions 8a and 8b at both ends of the light receiving element 4. It is characterized by that.

  The optical distance measuring device 50 configured as described above performs linear approximation by the least square method using the intensity distributions SA and SB of the partial regions 8a and 8B at both ends of the light receiving element 4, and thus the intensity distribution S20 of the cover reflected light F2 Can be approximated most accurately.

  Further, the distance measuring device 50 according to an embodiment is characterized in that a measurement error is determined when the correlation coefficient is equal to or less than a predetermined threshold in the linear approximation by the least square method.

  The optical distance measuring device 50 configured as described above has a function of determining a measurement error when the correlation coefficient is equal to or less than a threshold in the linear approximation by the least square method. For this reason, the distance measuring device 50 calculates distance correction accuracy by calculating an incorrect correction coefficient due to the incident of unintended light on the edge of the light receiving element 4 due to the influence of ambient light, dirt, scratches, etc. of the protective cover 20. Can be prevented. Further, the positional relationship (for example, an angle) between the protective cover 20 and the distance measuring device 50 changes due to vibration, impact, etc., and the state of reflection from the protective cover 20 changes, so that it is not assumed at the end of the light receiving element 4. There may be a case where light enters. The distance measuring device 50 can prevent such a decrease in distance measurement accuracy in the case.

  In the distance measuring device 50 according to an embodiment, the correction calculation unit 6 uses the intensity distributions SA and SB of the partial regions 8a and 8b at both ends of the light receiving element 4 to use the intensity distribution SA (SB) at one end. ) And the average value of the intensity distribution SB (SA) at the other end are linearly approximated.

  The optical distance measuring device 50 configured as described above calculates a correction coefficient by performing linear approximation from the average value of the intensity distribution SA (SB) at one end of the light receiving element 4 and the average value of the intensity distribution SB (SA) at the other end. It is also possible to do. For this reason, since the distance measuring device 50 is simpler to calculate than the least square method, the scale of the signal processing circuit (signal processing unit 5) can be reduced.

  In the distance measuring device 50 according to an embodiment, the light receiving area 8 of the light receiving element 4 is larger than the intensity distribution S10 of the reflected light F1 of the measurement object 10.

  In the optical distance measuring device 50 having the above configuration, the light receiving area 8 of the light receiving element 4 is larger than the light spot light size (range of the intensity distribution S10) of the measurement object 10, and both ends of the light reception area 8 are at the measurement object 10. It is located outside the light spot size. For this reason, the distance measuring device 50 can accurately approximate the intensity distribution S20 of the cover reflected light F2.

In the distance measuring apparatus 50 according to an embodiment, the correction calculation unit 6 performs linear approximation by least square method for the intensity distributions SA and SB of the partial regions 8a and 8b at both ends of the light receiving element 4, When the difference between the inclinations k (A) and k (B) at both ends is larger than a predetermined threshold value, a correction coefficient is calculated from the intensity distribution SA (SB) at one end of the light receiving element 4, and either end When the correlation coefficient R ² (A) (R ² (B)) is greater than a predetermined threshold value, the correction coefficient is calculated from the intensity distribution SB (SA) at the other end.

  In the optical distance measuring device 50 having the above configuration, when the measurement object 10 is at a close distance, the intensity distribution S0 of the reflected light F1 of the measurement object 10 is distributed to one end side of the light receiving element 4. The intensity distribution S0 tends to be a curve due to the influence of the tail portion of the spot light of the reflected light F1 of the measurement object 10. When the correlation coefficient of linear approximation by the least square method of the intensity distribution SB (SA) on one end side of the light receiving element 4 is larger than a predetermined threshold value, the intensity distribution SA (SB) on the other end side Only with this, the correction coefficient is calculated. Since the correction can be performed only with the intensity distribution S20 by the cover reflected light F2, the distance measuring device 50 can prevent a decrease in distance measurement accuracy.

  Also, an electronic device (personal computer 200) according to an embodiment is characterized in that the optical distance measuring device 50 is mounted.

  When an optical distance measuring device having a function of correcting reflected light by these protective covers is mounted on a personal computer or a sanitary device, these electronic devices can detect the distance to a person and control the device. When the distance measuring device is mounted on a self-propelled cleaner, the electronic device can detect an obstacle or a step. The distance measuring apparatus is suitable for use as a sensor for controlling an electronic device as a non-contact switch or a non-contact controller.

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light emission optical system (light emitting lens)
3 Light receiving optical system (light receiving lens)
4 Light Receiving Element 5 Signal Processing Unit 6 Correction Calculation Unit 7 Distance Calculation Unit 8 Light Receiving Area 8a A Part (One Partial Area)
8b B part (the other partial area)
10 Measurement object 50 Optical distance measuring device 200 Personal computer (electronic equipment)
F1 Reflected light from measurement object F2 Reflected light from protective cover S0 Measurement object intensity distribution S10 Measurement object intensity distribution S20 Protection cover intensity distribution SA A part intensity distribution SB B part intensity distribution

Claims (5)

A light emitting element;
A light-emitting optical system that focuses a light beam emitted from the light-emitting element and irradiates the measurement object with spot light; and
A light receiving optical system for collecting the reflected light from the measurement object;
A light receiving element for detecting spot light from the measurement object collected by the light receiving optical system;
A signal processing unit for processing a light reception signal from the light receiving element,
The light receiving element is a line sensor or an area sensor that detects an intensity distribution of reflected light from the measurement object,
The signal processor is
Calculating a spot position on the light receiving element of the spot light collected by the light receiving optical system, and detecting a distance from the spot position to the measurement object; and
Cover reflection in which light reflected by a translucent protective cover disposed between the light emitting optical system and the light receiving optical system and the measurement object is detected by the light receiving element via the light receiving optical system A correction calculation unit that detects the light intensity distribution and corrects the calculation of the distance,
The correction calculation unit calculates a correction coefficient corresponding to the intensity distribution of the cover reflected light from the intensity distribution of at least one partial region of both ends of the light receiving element to correct the intensity distribution of the spot light,
The optical distance measuring device, wherein the distance calculation unit calculates the distance to the measurement object based on an output of the correction calculation unit.   2. The optical according to claim 1, wherein the correction calculation unit calculates the correction coefficient by linearly approximating the intensity distribution of the cover reflected light from the intensity distribution of the partial region at both ends of the light receiving element. Type distance measuring device.   The optical distance measuring device according to claim 2, wherein the correction calculation unit performs linear approximation by a least square method using intensity distributions of the partial regions at both ends of the light receiving element.   The correction calculation unit performs linear approximation from the average value of the intensity distribution at one end and the average value of the intensity distribution at the other end using the intensity distribution of the partial region at both ends of the light receiving element. Item 3. The optical distance measuring device according to Item 2. The correction calculation unit performs linear approximation by least square method for the intensity distribution of the partial region at both ends of the light receiving element,
When the difference in inclination between the both ends is larger than a predetermined threshold value, a correction coefficient is calculated from the intensity distribution at one end of the light receiving element,
4. The optical distance measuring device according to claim 3, wherein when one of the correlation coefficients is larger than a predetermined threshold, the correction coefficient is calculated from the intensity distribution at the other end.

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