Measuring device and measuring method

Abstract

In a measuring device, a light-receiving area is divided into a measurement area defined by a first boundary, and is also divided into a peak position identification area defined by a second boundary different from the first boundary, and each peak position identification area includes at least a part of one measurement area and a part of an adjacent measurement area. The light-receiving area includes a merged area formed by two adjacent measurement areas. A signal processing unit is configured to: determine a target peak position identification area including a light-receiving element with the largest light-receiving amount; estimate the light-receiving amount of an interference light component in a target merged area including the peak position identification area based on a representative value of the light-receiving amount in the measurement area outside the target merged area; and control a threshold value based on the estimated amount.

Description

Technical Field

[0001] The present disclosure relates to a measuring device and a measuring method for optically measuring an object using a threshold value. Background Art

[0002] Conventionally, a measuring device that measures the displacement of an object, the surface shape of an object, etc. using the triangulation principle has been known. The measuring device irradiates an object with light projected from a light projecting unit, receives the reflected light from the object through an image sensor, detects the light receiving center position based on the amount of received light in each pixel of the image sensor, and measures the displacement of the object, etc. based on the light receiving center position.

[0003] Specifically, when sequentially reading the amount of received light (received light signal level) in each pixel of the image sensor, the received light signal level in each pixel is compared with a preset threshold value, and the pixel range in which the received light signal level is equal to or greater than the threshold value is set as the calculation range. Then, the peak position in the received light signal level distribution (received light waveform) is obtained within the set calculation range, and the obtained position is detected as the light receiving center position.

[0004] An optical distance measuring device is known as a measuring device of the related art. The optical distance measuring device includes: a light emitting element; a light emitting optical system that focuses the light beam emitted from the light emitting element and irradiates the measurement object with point light; a light receiving optical system that converges the reflected light from the measurement object; a light receiving element that detects the point light from the measurement object converged by the light receiving optical system; and a signal processing unit that processes the received light signal from the light receiving element. The light receiving element is a line sensor or a surface sensor that detects the intensity distribution of the reflected light from the measurement object. The signal processing unit includes: a distance calculation unit that calculates the point position of the point light converged by the light receiving optical system on the light receiving element and detects the distance from the point position to the measurement object; and a correction calculation unit that corrects the calculation of the distance by detecting the intensity distribution of the cover reflected light, wherein the light reflected by the light transmissive protective cover provided between the measurement object and the light emitting optical system and the light receiving optical system is detected by the light receiving element via the light receiving optical system. The correction calculation unit calculates a correction coefficient corresponding to the intensity distribution of the cover reflected light based on the intensity distribution in at least a partial region at one end of the light receiving element to correct the intensity distribution of the point light, and the distance calculation unit calculates the distance to the measurement object based on the output of the correction calculation unit.

[0005] Patent Document 1: JP2014-224726A Summary of the Invention

[0006] In Patent Document 1, the light-receiving region of the light-receiving element has a central portion and two end portions. When the peak of the received light amount appears near the boundary between the central portion of the light-receiving region and one of the two end portions, the light intensity distribution has a mountain shape (Gaussian shape), and thus the foot of the light intensity distribution enters the region (one of the two end portions or the central portion) adjacent to the region (the central portion or one of the two end portions) where the peak of the received light amount is located. Therefore, in Patent Document 1, the accuracy of correcting the signal (noise, interfering light, etc.) reflected by the protective cover and detected by the light-receiving element may be reduced. As a result, the influence of the interfering light remains, and the measurement accuracy of the object may be reduced.

[0007] The present disclosure provides a measuring device and a measuring method capable of reducing the influence of interfering light and improving the measurement accuracy of an object.

[0008] The present disclosure provides a measuring device for optically measuring an object using a threshold value, the measuring device including: a light-projecting unit configured to project first projection light onto the object; a light-receiving unit including a plurality of light-receiving elements, the light-receiving unit being configured to generate a first light-receiving signal in response to receiving first reflected light obtained by reflecting or scattering the first projection light by the object; and a signal processing unit configured to process the first light-receiving signal, wherein the light-receiving region including the plurality of light-receiving elements of the light-receiving unit is divided into a plurality of measurement regions defined by a plurality of first boundaries, the plurality of first boundaries dividing the plurality of light-receiving elements into a plurality of groups corresponding to the plurality of measurement regions, each group of the plurality of groups including one or more light-receiving elements, and the light-receiving region is also divided into a plurality of peak position identification regions defined by a plurality of second boundaries different from the plurality of first boundaries, wherein each peak position identification region of the plurality of peak position identification regions includes at least a part of one measurement region and a part of another measurement region adjacent to the one measurement region, wherein the light-receiving region includes a plurality of merged regions, and each merged region of the plurality of merged regions is formed by two adjacent measurement regions among the plurality of measurement regions, and wherein the signal processing unit is configured to: determine a target peak position identification region as one of the plurality of peak position identification regions, the target peak position identification region including the position of the light-receiving element having the largest received light amount in the first light-receiving signal; estimate the received light amount of the interfering light component in a target merged region as one of the plurality of merged regions, the target merged region including the target peak position identification region, the estimation being based on the representative value of the received light amount in each of at least two measurement regions located outside the target merged region among the plurality of measurement regions; and control the threshold value based on the received light amount of the interfering light component.

[0009] The present disclosure provides a measurement method for optically measuring an object using a threshold, the measurement method comprising: a step of projecting a first projection light onto the object; a step of generating a first light reception signal by a light reception unit including a plurality of light reception elements in response to receiving first reflected light obtained by reflecting or scattering the first projection light by the object; and a step of processing the first light reception signal, wherein a light reception region of the plurality of light reception elements including the light reception unit is divided into a plurality of measurement regions defined by a plurality of first boundaries, the plurality of first boundaries dividing the plurality of light reception elements into a plurality of groups corresponding to the plurality of measurement regions, each group of the plurality of groups including one or more light reception elements, and the light reception region is also divided into a plurality of peak position identification regions defined by a plurality of second boundaries different from the plurality of first boundaries, wherein each peak position identification region of the plurality of peak position identification regions includes at least a part of one measurement region and a part of another measurement region adjacent to the one measurement region, wherein the light reception region includes a plurality of merging regions, and each merging region of the plurality of merging regions is formed by two adjacent measurement regions among the plurality of measurement regions, and wherein the step of processing the first light reception signal includes: a step of determining a target peak position identification region as one of the plurality of peak position identification regions, the target peak position identification region including the position of the light reception element having the largest light reception amount in the first light reception signal; a step of estimating the light reception amount of the interference light component in a target merging region as one of the plurality of merging regions, the target merging region including the target peak position identification region, the estimation being based on representative values of the light reception amounts in at least two measurement regions located outside the target merging region among the plurality of measurement regions; and a step of controlling the threshold based on the light reception amount of the interference light component.

[0010] According to the present disclosure, the influence of interference light can be reduced, and the measurement accuracy of the object can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present disclosure will be described in detail based on the following drawings, wherein:

[0012] Figure 1 is a conceptual diagram showing a situation where a measurement device projects projection light onto an object and receives reflected light according to an embodiment of the present disclosure;

[0013] Figure 2 is a block diagram showing an example of the measurement device;

[0014] Figure 3 is a diagram showing an example of a light reception signal, a measurement region, a peak position identification region, and a merging region generated by the light reception unit;

[0015] Figure 4 is a conceptual diagram showing an example of determining a peak position by the measurement device and an example of estimating the light reception amount of interference light;

[0016] Figure 5 is a graph showing another example of the amount of received light of the interfering light component estimated by the measuring device. Detailed Description

[0017] Hereinafter, embodiments will be described in detail with appropriate reference to the drawings. Unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. The drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the scope of the claims.

[0018] Figure 1 is a conceptual diagram showing a situation where a measuring device according to an embodiment of the present disclosure projects projection light onto an object and receives reflected light. In the measuring device 50, the light projecting unit 1 projects projection light L1 onto the object 10, and the light receiving unit 4 receives the reflected light L2 obtained by reflecting or scattering the projection light L1 by the object 10. The measuring device 50 optically measures the object 10 based on the received light signal obtained from the reflected light L2. The measuring device 50 can operate as, for example, a measurement sensor, a displacement sensor, or a distance measurement sensor. The measuring device 50 can measure, for example, an absolute distance or a relative distance. For example, the measuring device 50 can also detect whether there is a displacement such as unevenness or the amount of displacement relative to a reference plane.

[0019] Figure 2 is a block diagram showing an example of the measuring device 50 according to the present embodiment. The measuring device 50 includes a light projecting unit 1, a light emitting lens 2, a light receiving lens 3, a light receiving unit 4, a signal processing unit 5, and a storage unit 5M. The light projecting unit 1 includes a light emitting element or the like. The light emitting element includes, for example, a laser diode.

[0020] The light receiving unit 4 includes a plurality of light receiving elements. The light receiving elements are, for example, semiconductor light receiving elements including a photodiode or a complementary metal oxide semiconductor (CMOS), and convert the optical signal of the received light into an electrical signal. The light receiving unit 4 generates a received light signal through the light receiving elements in response to receiving the reflected light L2 obtained by reflecting or scattering the projection light L1 by the object 10. The light receiving unit 4 constitutes a line sensor in which the light receiving elements are arranged in a row on the x-axis, and can be a surface sensor in which the light receiving elements are arranged on a two-dimensional plane.

[0021] In Figure 2 , the projection light L1 projected from the light projecting unit 1 is incident on the object 10, and the reflected light L2 from the object 10 is incident on the light receiving unit 4 of the measuring device 50. The reflected light L2 shown in the figure represents the optical axis detected by the light receiving unit 4 as a result of multiple reflections.

[0022] The projection light L1 projected from the light projection unit 1 is emitted via the light-emitting lens 2. Most of the emitted light beam of the projection light L1 irradiates the object 10. The reflected light L2 from the object 10 at a sufficiently distant position is converged by the light-receiving lens 3 to form a light spot on the light-receiving unit 4. The light-receiving area 8 of the light-receiving unit 4 has a size required for detecting the intensity distribution S20 of the object 10 (see Figure 3 ). The light-receiving area 8 is an area including a plurality of light-receiving elements.

[0023] The signal processing unit 5 includes, for example, a processor. The processor implements various functions (or performs various operations) of the signal processing unit 5 by executing a program (or instructions) stored in the storage unit 5M. The processor may include a microprocessing unit (MPU), a central processing unit (CPU), a digital signal processor (DSP), etc. The processor may be implemented by various integrated circuits (e.g., large-scale integration (LSI) or field-programmable gate array (FPGA)). The signal processing unit 5 controls the units of the measuring device 50 as a whole and performs various types of processing. The signal processing unit 5 includes a threshold control unit 6 and a distance calculation unit 7.

[0024] The storage unit 5M includes a main storage device (e.g., a random access memory (RAM) or a read-only memory (ROM)). The memory 13 may include a secondary storage device, a tertiary storage device, etc., or may include a removable storage medium. The storage unit 5M stores various data, information, etc. The storage unit 5M may store information about the light-receiving signal (information about the light-receiving waveform indicating the light-receiving signal). The information about the light-receiving signal is used to control the threshold th for measuring the object 10.

[0025] The threshold control unit 6 controls the threshold th for measuring the object 10. Details of the threshold control unit 6 will be described later.

[0026] The distance calculation unit 7 measures the object 10 based on which of the plurality of light-receiving elements of the light-receiving unit 4 receives light. The distance calculation unit 7 may calculate the distance from the measuring device 50 to the object 10. Information about the detection distance for each light-receiving element (unit distance information) may be stored in the storage unit 5M. The distance calculation unit 7 may calculate the distance to the object 10 based on the unit distance information. The distance calculation unit 7 identifies one or more light-receiving elements in the light-receiving signal S1 received by the light-receiving unit 4 (see Figure 3 ) whose light-receiving amount is equal to or greater than the threshold th. The distance calculation unit 7 may calculate the distance to the object 10 based on the positions of the identified light-receiving elements.

[0027] Figure 3FIG. is a diagram showing an example of a received light signal S1 generated by a light receiving unit 4, a measurement region R1, a peak position identification region R2, and a merging region TR. Figure 4 FIG. is a conceptual diagram showing an example of determining a peak position by a measuring device 50 and an example of estimating a received light amount of interfering light. Figure 4 is Figure 3 an enlarged view of measurement regions R10 to R13 in the chart of

[0028] Figure 3 shows a received light signal S1 generated by the light receiving unit 4 based on the intensity distribution (reflected light profile) of the reflected light L2 received in the light receiving region 8 of the light receiving unit 4. Figure 3 The horizontal axis (corresponding to the x-axis) in is the coordinate axis of the light receiving region 8, and the number of each light receiving element (light receiving element number) among a plurality of arranged light receiving elements is assigned thereto. The plurality of light receiving elements are arranged in the same direction as the Figure 1 direction in which the light projecting unit 1 and the light receiving unit 4 are arranged in.

[0029] The light receiving region 8 is divided into a plurality of measurement regions R1 defined by a first boundary B1 that uniformly divides a plurality of light receiving elements. In Figure 3 , the light receiving region 8 includes eight measurement regions R1 (R10 to R17).

[0030] Figure 3 shows an example in which the light receiving unit 4 constitutes a line sensor. In the case where the light receiving unit 4 constitutes a surface sensor, a plurality of measurement regions are generated on the plane of the chart of Figure 3 along an axis perpendicular to the x-axis.

[0031] Figure 3 The vertical axis (y-axis) in indicates the received light amount (for example, a numerical value obtained by AD-converting a voltage) at each light receiving element (each light receiving position). That is, it shows the received light amount in the received light signal S1 generated by the light receiving unit 4 based on the reflected light L2. The intensity distribution of the received light amount in the received light signal S1 has the following shape: the intensity distribution S20 of the received light amount from the object 10 is added to the intensity distribution S10 of the received light amount that increases in any direction along the x-axis (in this example, the left direction).

[0032] In Figure 3In [description], the intensity distribution S10 has a shape that rises to the left, that is, the value (light reception amount) increases as the light reception amount in the light reception signal S1 received by the light reception element with a smaller light reception element number increases. This phenomenon is caused by the action of interfering light from the surroundings and is a phenomenon common in measurement devices. That is, the intensity distribution S10 corresponds to the light reception amount of the interfering light component. The intensity distribution S20 has a shape with a predetermined peak according to the so-called Gaussian distribution, and this peak corresponds to the reflected light L2 from the object 10.

[0033] The interfering light that appears in the intensity distribution S10 includes, for example, ambient light. Ambient light includes light such as sunlight or the illumination around the measurement device 50. When the interfering light is reflected or scattered by the object 10, the interfering light can be received by the light reception unit 4 as an interfering light component, which is a part of the component of the reflected light L2.

[0034] In Figure 3 In [description], the peak of the intensity distribution S20 exists in the measurement region R12, and the threshold control unit 6 processes the light reception signal S1 and determines that the reflected light L2 from the object 10 is received in the measurement region R12. The distance calculation unit 7 calculates the distance to the object 10 based on the measurement region R1 where the reflected light L2 is received. In this case, the distance calculation unit 7 compares the light reception amount of each light reception element with the threshold th set by the threshold control unit 6, and sets the distance measurement calculation range to include only the light reception elements whose light reception amount is equal to or greater than the threshold th. The distance calculation unit 7 calculates the peak position of the intensity distribution S20 within the set distance measurement calculation range and detects this position as the light reception center position. Therefore, the measurement device 50 can reduce the calculation error. The distance calculation unit 7 can derive the distance corresponding to the detected light reception position based on the unit distance information.

[0035] In Figure 3 In [description], the dark level is preset as the light reception amount in the signal that is always generated even when the light reception unit 4 does not detect light. For example, the dark level is set to a predetermined value when the measurement device 50 is started and stored in the storage unit 5M. For example, when the measurement device 50 is started, the signal processing unit 5 sets the initial setting threshold th1 and stores the initial setting threshold th1 in the storage unit 5M. The initial setting threshold th1 can be preset as the light reception amount that can usually be applied. When the initial setting threshold th1 is set, the distance calculation unit 7 only sets the light reception elements that detect a light reception amount greater than the initial setting threshold th1 as the calculation targets for measuring the object 10.

[0036] Here, the environment of the measuring device 50 varies greatly, and the initially set threshold th1 may not be an appropriate light reception amount depending on the situation. Therefore, the threshold control unit 6 estimates the light reception amount of the interfering light component and controls the threshold th based on the estimated light reception amount of the interfering light component. In Figure 3 the example of Figure 3 , the initially set threshold th1 is too small, and all the light receiving elements become calculation targets for the distance calculation unit 7 to derive the light reception center position. Therefore, the threshold control unit 6 determines the intensity distributions S10 and S20, and determines the estimated threshold th2 corresponding to the light reception amount (i.e., the light reception waveform) in the light reception signal S1. That is, the threshold control unit 6 changes the initially set threshold th1 to the estimated threshold th2 (

[0037] arrow C2 in

[0038] ). The measuring device 50 can reduce the calculation error by optically measuring the object 10 using the estimated threshold th2.

[0039] For example, when the amount of the interfering light component is large, that is, when the measuring device 50 is arranged in an environment brighter than the environment corresponding to the initially set threshold th1, the estimated threshold th2 is changed to be greater than the initially set threshold th1. When the amount of the interfering light component is small, that is, when the measuring device 50 is arranged in an environment darker than the environment corresponding to the initially set threshold th1, the estimated threshold th2 is changed to be less than the initially set threshold th1. In addition to the brightness, the threshold th can also be changed based on the temperature.

[0040] The second boundary B2 is set, for example, at the central position of each of the measurement regions R11 to R16 on the x-axis, that is, the central position of each of the measurement regions R11 to R16 in the arrangement direction of the light-receiving elements. In other words, the second boundary B2 is set, for example, at the central position between two adjacent first boundaries B1. However, the position of the second boundary B2 is not limited to this example as long as the second boundary B2 does not overlap with the first boundary B1.

[0041] In Figure 3 it, the peak position identification region R2 includes seven peak position identification regions R2 (R20 to R26) as described below.

[0042] Each of the peak position identification regions in the plurality of peak position identification regions R2 includes a part of each of two adjacent measurement regions R1. For example, the peak position identification region R21 includes a part (right half) of the measurement region R11 and a part (left half) of the measurement region R12. Two adjacent measurement regions R1 form a merged region TR where the two measurement regions R1 are merged.

[0043] In the present embodiment, the merged region TRxy is represented, where x is the trailing symbol of one of the two adjacent measurement regions R1 (with a smaller symbol), and y is the trailing symbol of the other measurement region R1 (with a larger symbol) among the two adjacent measurement regions R1. For example, the merged region TR including the measurement regions R11 and R12 is the merged region TR12. Similarly, the relationship between the merged region TR and the measurement region R1 is as follows, for example.

[0044] Merged region TR01: Measurement regions R10, R11

[0045] Merged region TR12: Measurement regions R11, R12

[0046] Merged region TR23: Measurement regions R12, R13

[0047] Merged region TR34: Measurement regions R13, R14

[0048] Merged region TR45: Measurement regions R14, R15

[0049] Merged region TR56: Measurement regions R15, R16

[0050] Merged region TR67: Measurement regions R16, R17

[0051] The threshold control unit 6 determines the peak position identification region R2 that includes the maximum light-receiving position in the light-receiving signal S1. The maximum light-receiving position is the position of the light-receiving element with the largest light-receiving amount in the light-receiving signal S1. In Figure 3In this case, the threshold control unit 6 determines that the peak position identification region R21 includes the maximum light reception position.

[0052] The threshold control unit 6 determines that the peak position identification region R21 including the maximum light reception position includes a part (right half) of the measurement region R11 and a part (left half) of the measurement region R12, and determines that the peak position identification region R21 is included in the merging region TR12. The threshold control unit 6 calculates a representative value of the light reception amount in each of the plurality of measurement regions R1 located outside the peak position identification region R21 (i.e., outside the merging region TR corresponding to the peak position identification region R21). In this example, the threshold control unit 6 calculates a representative value of the light reception amount in each of the measurement regions R10 and R13 located outside the peak position identification region R21. Since the first boundary B1 and the second boundary B2 do not overlap with each other, the measurement regions R10 and R13 are adjacent to the merging region TR12 corresponding to the peak position identification region R21 and are outside this merging region TR12.

[0053] In Figure 3 this case, the representative value of the light reception amount in the measurement region R10 is the light reception amount A0. The representative value of the light reception amount in the measurement region R13 is the light reception amount A3. For example, the threshold control unit 6 calculates the light reception amount A T12 in the merging region corresponding to the peak position identification region R21 including the maximum light reception position (e.g., at the center position of the merging region TR on the x-axis) based on the light reception amount A0 in the measurement region R10 and the light reception amount A3 in the measurement region R13. T12 The light reception amount A T12 indicates the representative value of the light reception amount in the merging region TR. Based on the straight line D connecting the light reception amounts A0 and A3 as representative values, the threshold control unit 6 can calculate the light reception amount A

[0054] in the merging region TR12, for example, as a value on the straight line D. The threshold control unit 6 calculates the offset light reception amount in the measurement region R1 by subtracting the light reception amount at the dark level from the representative value of the light reception amount in the measurement region R1. The offset light reception amount is calculated in the same way not only for the measurement region R1 but also for the merging region TR. Therefore, the threshold control unit 6 calculates the offset light reception amount in the measurement region R1 by subtracting the light reception amount at the dark level from the light reception amount A T12 in the merging region TR12.

[0055] In this way, the threshold control unit 6 calculates the offset received light amount in the combined region TR12 based on the received light amounts A0 and A3 that are representative values in the measurement regions R10 and R13, respectively. The threshold control unit 6 determines the estimated threshold th2 based on the initial set threshold th1 and the offset received light amount in the combined region TR12. In this case, the threshold control unit 6 can determine the estimated threshold th2 by adding the offset received light amount in the combined region TR12 to the initial set threshold th1.

[0056] The calculation of the offset value in the combined region TR12 corresponding to the peak position identification region R21 including the maximum received light position corresponds to the estimation of the received light amount of the interference light component in the combined region TR12. Then, the threshold control unit 6 controls the threshold th based on the offset received light amount corresponding to the estimated received light amount of the interference light component. Therefore, the measuring device 50 can appropriately set the threshold th and can appropriately limit the distance measurement calculation range of the received light center position for measuring the object 10.

[0057] In the present embodiment, for example, even when the maximum received light position in the received light signal S1 exists near the first boundary B1 that is the boundary between the two measurement regions R1, the maximum received light position does not exist near the first boundary B1 (the boundary between the measurement regions R12 and R13) that is the outer edge of the combined region TR12 corresponding to the peak position identification region R2 including the maximum received light position. That is, even when the maximum received light position exists near the boundary (the first boundary B1) of the two measurement regions R1, the maximum received light position exists at a position deviated from the boundary (outer edge) of the combined region TR including the maximum received light position (near the center position of the combined region TR). Therefore, it is possible to prevent the foot portion having a large value where the received light amount in the received light signal S1 decreases from the maximum received light position from entering the outside of the combined region TR including the maximum received light position. Therefore, the measuring device 50 can prevent the original signal component of the received light signal S1 from entering the received light amount from which the offset received light amount is derived, and thus can accurately derive the offset received light amount. Therefore, the measuring device 50 can appropriately determine the threshold th.

[0058] Even when the maximum light-receiving position in the received light signal S1 exists near the boundary (second boundary B2) between two adjacent peak position recognition regions R2, the outer edge (first boundary B1) of the merged region TR corresponding to the peak position recognition region R2 is located outside the position of the second boundary B2. Therefore, it is possible to prevent the foot portion having a relatively large value where the received light amount in the received light signal S1 decreases from the maximum light-receiving position from entering the outside of the merged region TR including the maximum light-receiving position. Therefore, the measuring device 50 can prevent the original signal component of the received light signal S1 from entering the received light amount from which the offset received light amount is derived, and thus can derive the offset received light amount with high precision. Therefore, the measuring device 50 can appropriately determine the threshold th.

[0059] Figure 3 It also includes a graph showing an example of the received light amount of the interference light component estimated by the measuring device 50. The threshold control unit 6 can estimate the received light amount of the interference light component based on the representative value of the received light amount in each of the two measurement regions R10 and R13 adjacent to the two outer sides of the merged region TR12 corresponding to the determined peak position recognition region R21 in the received light signal S1. In this case, the threshold control unit 6 can calculate the average value of the received light amounts received by a plurality of light-receiving elements included in the measurement region R1 as the representative value of the received light amount in the received light signal S1 for each measurement region R1. The representative value of the received light amount may be a value other than the average value (for example, the maximum value or the minimum value).

[0060] When the average value of the received light amount of each measurement region R1 is used as the representative value of the received light amount, the threshold control unit 6 can estimate the offset received light amount in the merged region TR including the maximum light-receiving position according to the following steps. For example, as Figure 3 shown, when the maximum light-receiving position is included in the peak position recognition region R21, the merged region TR12 is recognized corresponding to the peak position recognition region R21. For example, the threshold control unit 6 calculates the offset received light amount in the merged region TR12 according to (A0 + A3) / 2. When the maximum light-receiving position is included in the peak position recognition region R22, the merged region TR23 is recognized corresponding to the peak position recognition region R22. For example, the threshold control unit 6 calculates the offset received light amount in the merged region TR23 according to (A1 + A4) / 2. Here, the received light amount A n is the representative value (for example, the average value) of the received light amount in the measurement region R1n.

[0061] Figure 5 is a graph showing other examples of the received light amount of the interference light component estimated by the measuring device 50. In Figure 5In the example, the peak position (maximum light-receiving position) of the intensity distribution S20 is located in the peak position recognition region R20. In this example, there is no adjacent measurement region R1 on the left side (the smaller side on the x-axis (the horizontal axis in Figure 5 the x-axis in Figure 5 ) of the merging region TR01 corresponding to the peak position recognition region R20). Therefore, the threshold control unit 6 can estimate the light-receiving amount of the interfering light component based on the light-receiving amounts A2 and A3, which are representative values in the two measurement regions R12 and R13 adjacent to and on one outer side (e.g., the right side, the larger side on the x-axis) of the merging region TR01 in the light-receiving signal S1.

[0062] For example, as Figure 5 shown, when the maximum light-receiving position is included in the peak position recognition region R20, the merging region TR01 is recognized corresponding to the peak position recognition region R20. For example, the threshold control unit 6 calculates the offset light-receiving amount in the merging region TR01 according to (5A2 - 3A3) / 2. Therefore, even when the peak position recognition region R2 or the merging region TR including the maximum light-receiving position is located at the end of the light-receiving region 8, the measuring device 50 can use the outer division point to estimate the offset light-receiving amount in the merging region TR and can determine an appropriate threshold th.

[0063] The threshold control unit 6 can estimate the offset light-receiving amount in the merging region TR based on the representative value of the light-receiving amount in each of the plurality of measurement regions R1 that are not adjacent to the merging region TR including the maximum light-receiving position. The threshold control unit 6 can also estimate the offset light-receiving amount in the merging region TR based on the representative values of the light-receiving amounts in three or more measurement regions R1 on the outer side of the merging region TR including the maximum light-receiving position. When three or more light-receiving amounts are obtained, the threshold control unit 6 can estimate the offset light-receiving amount in the merging region TR according to various known approximation methods instead of the linear approximation method.

[0064] Next, the changes in the threshold control will be described.

[0065] The threshold control unit 6 can control the threshold th so as not to exceed the upper limit value. By adjusting the light projection time of the projection light L1 from the light projection unit 1, the light-receiving amount of the light-receiving unit 4 can be adjusted. The upper limit value of the threshold th is determined in consideration of the light-receiving amount of the light-receiving unit 4 and the receivable light amount. The light projection unit 1 can adjust the light projection amount to be equal to or greater than the upper limit value of the threshold th and equal to or less than the upper limit value of the receivable light amount. The upper limit value of the threshold th can be stored in the storage unit 5M.

[0066] For example, in a case where the threshold th is controlled to change from an initial set threshold th1 to an estimated threshold th2, the threshold control unit 6 can determine the estimated threshold th2 as the upper limit value when the estimated value of the estimated threshold th2 is equal to or greater than the upper limit value. The estimated value of the estimated threshold th2 is an initial estimated threshold th2 calculated by the threshold control unit 6 considering the offset received light amount in the merging region TR without considering the upper limit value. Therefore, the threshold control unit 6 can prevent the estimated threshold th2 from being too large.

[0067] The threshold control unit 6 can control the change amount of the threshold th not to exceed the upper limit change amount. For example, in a case where the control threshold th is controlled to change from an initial set threshold th1 to an estimated threshold th2, the threshold control unit 6 can, when the difference between the initial set threshold th1 and the estimated value of the estimated threshold th2 is greater than a predetermined value (i.e., when the change amount of the threshold th is greater than the upper limit change amount), determine the estimated threshold th2 by adding the upper limit change amount to the initial set threshold th1. Therefore, the threshold control unit 6 can prevent a rapid change in the estimated threshold th2 and a rapid change in the measurement result of the object 10 using the estimated threshold th2.

[0068] The timing at which the threshold control unit 6 performs threshold control is arbitrary. For example, the timing of threshold control and the measurement timing of the object 10 can be the same. For example, the threshold control unit 6 can control the threshold th each time the object 10 is measured. The threshold control unit 6 can control the threshold th each time the received light signal S1 (received light waveform) is acquired.

[0069] The timing of threshold control and the measurement timing of the object 10 can be different timings. For example, the light projecting unit 1 can project measurement projection light different from the transmission light used for threshold control onto the object 10, and the light receiving unit 4 can generate a measurement received light signal S11 different from the received light signal used for threshold control in response to receiving the measurement reflected light obtained by the object 10 reflecting or scattering the projection light. The distance calculation unit 7 can identify the light receiving elements in the received light signal S11 received by the light receiving unit 4 whose received light amount is equal to or greater than the threshold th controlled by the threshold control unit 6, and can measure the object 10 based on the positions of the identified light receiving elements. That is, the distance calculation unit 7 can measure the object 10 using the measurement projection light and the measurement reflected light differently from the projection light L1 and the reflected light L2 used for threshold control.

[0070] In this way, the measuring device 50 according to the present embodiment uses the peak position identification region R2 different from the region (measurement region R1) during actual measurement (e.g., during distance measurement) to identify the peak position identification region R2 including the maximum light-receiving position. The measuring device 50 identifies the merged region TR corresponding to the identified peak position identification region R2, calculates the offset light-receiving amount in the merged region TR, and estimates the interfering light at, for example, the center position of the merged region TR. The estimated interfering light corresponds to the variable dark level. The measuring device 50 can adjust the threshold th according to the estimated interfering light.

[0071] For example, assume that the dark level changes by a relatively large value as a whole. In this case, the initially set threshold th1 is relatively small with respect to the dark level, and the number of light-receiving elements receiving a light-receiving amount greater than the initially set threshold th1 increases. That is, the reflected light L2 is received not only near the peak position but also in a relatively wide range of the light-receiving region 8 where the light-receiving amount is equal to or greater than the initially set threshold th1. In this case, the distance calculation unit 7 calculates the light-receiving center position in a relatively wide range of the light-receiving region 8, whereby the measurement accuracy of the object 10 can be reduced. On the contrary, according to the measuring device 50, the initially set threshold th1 is changed to the estimated threshold th2 according to the estimation result of the interfering light that changes due to the dark level. Therefore, the number of light-receiving elements receiving a light-receiving amount equal to or greater than the estimated threshold th2 in the light-receiving region 8 can be reduced, and the reflected light L2 corresponding to the light-receiving amount equal to or greater than the estimated threshold th2 is received only near the peak position in the light-receiving region 8. Therefore, the measuring device 50 can prevent the measurement accuracy of the object 10 from being reduced.

[0072] The measuring device 50 uses the light-receiving amount of the measurement region R1 outside the merged region TR where the maximum light-receiving position exists to derive the offset light-receiving amount in the merged region TR, and does not use the light-receiving amount in the merged region TR to derive the offset light-receiving amount in the merged region TR. In the merged region TR, the light-receiving amount in the signal component of the reflected light L2 (i.e., the component other than the interfering light that is originally expected to be obtained) obtained by reflecting or scattering the projected light L1 is large. Therefore, since the measuring device 50 can use the light-receiving amount in the measurement region R1 that excludes the component originally expected to be obtained and includes a large amount of interfering light components to derive the offset light-receiving amount in the merged region TR, the estimation accuracy of the interfering light can be improved.

[0073] In the present embodiment, the case where the offset light-receiving amount is positive is mainly illustrated, but the present invention is not limited thereto. The offset light-receiving amount of the interfering light can be negative. When the offset light-receiving amount of the interfering light is negative, the estimated threshold th2 is changed to be less than the initially set threshold th1. The threshold control unit 6 can estimate the interfering light at a position other than the center position of the merged region TR, for example, can estimate the interfering light at the maximum light-receiving position.

[0074] As described above, the measuring device 50 according to the above embodiment is configured to optically measure the object 10 using a threshold value. The measuring device 50 includes: a light projecting unit 1 that projects projection light L1 (an example of first projection light) onto the object 10; a light receiving unit 4 that includes a plurality of light receiving elements and is configured to generate a light receiving signal S1 (an example of a first light receiving signal) in response to receiving reflected light L2 (an example of first reflected light) obtained by reflecting or scattering the projection light L1 by the object 10; and a signal processing unit 5 that is configured to process the light receiving signal S1. The light receiving region 8 including the plurality of light receiving elements of the light receiving unit 4 is divided into a plurality of measurement regions R1 defined by a plurality of first boundaries B1. The plurality of first boundaries B1 divide the plurality of light receiving elements into a plurality of groups corresponding to the plurality of measurement regions R1. Each group of the plurality of groups includes one or more light receiving elements, and the light receiving region 8 is also divided into a plurality of peak position identification regions R2 defined by a plurality of second boundaries B2. The plurality of second boundaries B2 are different from the plurality of first boundaries B1. Each peak position identification region among the plurality of peak position identification regions R2 includes at least a part of one measurement region R1 and a part of another measurement region R1 adjacent to the one measurement region R1. The light receiving region 8 includes a plurality of merging regions TR, and each merging region among the plurality of merging regions TR is formed by two adjacent measurement regions among the plurality of measurement regions R1. The signal processing unit 5 is configured to determine a target peak position identification region R2 that is one of the plurality of peak position identification regions R2. The target peak position identification region R2 includes the position (maximum light receiving position) of the light receiving element having the largest light receiving amount in the light receiving signal S1. The signal processing unit 5 is configured to estimate the light receiving amount (offset light receiving amount) of the interfering light component in a target merging region TR that is one of the plurality of merging regions TR. The target merging region TR includes the target peak position identification region R2, and the estimation is based on the representative value of the light receiving amount in each of at least two measurement regions located outside the target merging region TR among the plurality of measurement regions R1. The signal processing unit 5 is configured to control the threshold value th based on the light receiving amount of the interfering light component.

[0075] Therefore, the measuring device 50 can control the threshold th by considering a merging region TR and a peak position identification region R2 for identifying the peak position in the received light signal S1 differently from the measurement region R1 for measuring the object 10. In this case, in the measuring device 50, even when the peak position (maximum received light position) is located at the boundary end of the measurement region R1, the peak position is not located at the end of the merging region TR. That is, when the peak position in the measurement region R1 is located at the boundary end of the measurement region R1, the merging region TR is selected such that the peak is near the center of the merging region TR. Therefore, the foot of the received light waveform indicating the received light signal S1 does not enter the outer region adjacent to the merging region TR. Thus, the signal component is located in the merging region TR, and the interfering light component other than the signal component is located outside the merging region TR. The measuring device 50 can use the received light amount outside the merging region TR to accurately estimate the received light level of the interfering light and can appropriately determine the threshold th for measuring the object 10. Therefore, the measuring device 50 can reduce the influence of the interfering light and improve the measurement accuracy of the object.

[0076] The signal processing unit 5 can estimate the received light amount of the interfering light component based on the representative value of the received light amount in each of the two measurement regions R1 adjacent to and on two outer sides of the target merging region TR including the target peak position identification region R2 in the received light signal S1.

[0077] Therefore, the measuring device 20 uses the received light amount in the measurement region R1 that basically does not include the signal component originally expected to be acquired and includes a large amount of interfering light components to estimate the received light amount of the interfering light component. Thus, the interfering light in the merging region TR can be accurately estimated.

[0078] The signal processing unit 5 can estimate the received light amount of the interfering light component based on the representative value of the received light amount in each of the two measurement regions R1 adjacent to and on one outer side of the target merging region TR including the target peak position identification region R2 in the received light signal S1.

[0079] Therefore, even when the peak position identification region R2 or the merging region TR including the maximum received light position is located at the end of the received light region 8, the measuring device 50 can use the outer division point to estimate the offset received light amount in the merging region TR and can determine an appropriate threshold th.

[0080] The representative value of the received light amount in each of the plurality of measurement regions R1 in the received light signal S1 can be the average value of the received light amounts indicated in the received light signal S1 and received by one or more light receiving elements included in the corresponding one of the plurality of measurement regions R1. Thus, a value representing the received light amount of the measurement region R1 can be appropriately obtained.

[0081] At least one of the plurality of second boundaries B2 can be set at the central position between two adjacent first boundaries among the plurality of first boundaries B1.

[0082] Therefore, the peak position recognition region R2 can include half of each of the two measurement regions R1. Therefore, the positional relationship among the measurement region R1, the peak position recognition region R2, and the merging region TR has symmetry. Therefore, the measuring device 50 can prevent estimating interference light in the merging region TR based on the amount of received light at a position on the x-axis of the light-receiving region 8 that is biased toward the larger side or the smaller side, and can improve the estimation accuracy in the interference light estimation.

[0083] In the case where the threshold is controlled to change from the initial set threshold th1 (an example of the first threshold) to the estimated threshold th2 (an example of the second threshold), when the estimated value of the estimated threshold th2 is equal to or greater than the upper limit value, the signal processing unit 5 can set the estimated threshold th2 to the upper limit value.

[0084] Therefore, the measuring device 50 can prevent the estimated threshold th2 from being too large in consideration of the characteristics of the light projecting unit 1 or the light receiving unit 4, etc.

[0085] In the case where the threshold is controlled to change from the initial set threshold th1 to the estimated threshold th2, when the difference between the initial set threshold th1 and the estimated value of the estimated threshold th2 is equal to or greater than the upper limit change amount, the signal processing unit 5 can set the estimated threshold th2 by adding the upper limit change amount to the initial set threshold th1.

[0086] Therefore, the measuring device 50 can prevent a rapid change in the estimated threshold th2 and a rapid change in the measurement result of the object 10 using the estimated threshold th2.

[0087] The signal processing unit 5 can be configured to: identify at least one light receiving element among the plurality of light receiving elements, the amount of received light indicated in the received light signal S1 and received by the light receiving unit 4 of the at least one light receiving element being equal to or greater than the threshold; and measure the object 10 based on the position of each of the at least one light receiving element.

[0088] Therefore, the measuring device 50 can determine the threshold th considering the interference light component at the same timing as the measurement timing. Therefore, the measuring device 50 can measure the object 10 with high precision in a short time.

[0089] The light projecting unit 1 may be configured to project another projection light (an example of the second projection light) onto the object 10. The light receiving unit 4 may be configured to generate another light receiving signal (an example of the second light receiving signal) in response to receiving another reflected light (an example of the second reflected light) obtained by reflection or scattering of the another projection light by the object 10. The signal processing unit 5 may be configured to identify at least one light receiving element among a plurality of light receiving elements, the amount of light received by the at least one light receiving element indicated in the another light receiving signal and received by the light receiving unit 4 being equal to or greater than a threshold th; and measure the object 10 based on the positions of each of the at least one light receiving element.

[0090] Therefore, the measuring device 50 can determine the threshold th while taking into account the interfering light component at a timing different from the measurement timing. Therefore, the measuring device 50 can determine the threshold th at another timing, reduce the processing load during measurement, and measure the object 10.

[0091] Although various embodiments have been described above with reference to the accompanying drawings, the present invention is of course not limited to these embodiments. Obviously, those skilled in the art can conceive of various modifications and changes within the scope described in the claims, and it should be understood that such modifications and changes naturally fall within the technical scope of the present invention. In addition, the constituent elements in the above embodiments can be arbitrarily combined without departing from the scope of the present invention.

[0092] In the above embodiments, a processor such as a CPU can be physically implemented in any manner. When a programmable processor is used, the processing content can be changed by changing the program, so the degree of freedom in designing the processor can be increased. The processor can be implemented by one semiconductor chip and can be physically implemented by a plurality of semiconductor chips. In the case of a plurality of semiconductor chips, the control according to the above embodiments can be implemented by different semiconductor chips. In this case, one processor can be considered to be implemented by a plurality of semiconductor chips. The processor can be implemented by a component (such as a capacitor) having a function different from that of a semiconductor chip. One semiconductor chip can implement the functions of the processor and other functions. The functions of a plurality of processors can be implemented by one processor.

[0093] The present disclosure is useful for a measuring device and a measuring method capable of reducing the influence of interfering light and improving the measurement accuracy of an object.

Claims

1. A measuring device for optically measuring an object using a threshold, the measuring device comprising: A light projecting unit configured to project first projected light onto the object; A light receiving unit including a plurality of light receiving elements, the light receiving unit being configured to generate a first light receiving signal in response to receiving first reflected light obtained by reflecting or scattering the first projected light by the object; And A signal processing unit configured to process the first light receiving signal, wherein a light receiving region including the plurality of light receiving elements of the light receiving unit is divided into a plurality of measurement regions defined by a plurality of first boundaries, the plurality of first boundaries dividing the plurality of light receiving elements into a plurality of groups corresponding to the plurality of measurement regions, each group of the plurality of groups including one or more light receiving elements, and the light receiving region is also divided into a plurality of peak position identification regions defined by a plurality of second boundaries different from the plurality of first boundaries, wherein each peak position identification region of the plurality of peak position identification regions includes at least a part of one measurement region and a part of another measurement region adjacent to the one measurement region, wherein the light receiving region includes a plurality of merging regions, and each merging region of the plurality of merging regions is formed by two adjacent measurement regions of the plurality of measurement regions, and wherein the signal processing unit is configured to: Determine a target peak position identification region among the plurality of peak position identification regions, the target peak position identification region including the position of the light receiving element with the largest light receiving amount in the first light receiving signal; Estimate the light receiving amount of the interfering light component in a target merging region among the plurality of merging regions, the target merging region including the target peak position identification region, the estimation being based on representative values of the light receiving amounts in at least two measurement regions located outside the target merging region among the plurality of measurement regions; and Control the threshold based on the light receiving amount of the interfering light component.

2. The measuring device according to claim 1, wherein, The signal processing unit is configured to: estimate the light receiving amount of the interfering light component based on representative values of the light receiving amounts in each of two measurement regions adjacent to and on two outer sides of the target merging region including the target peak position identification region in the first light receiving signal.

3. The measuring device according to claim 1, wherein, The signal processing unit is configured to: estimate the light receiving amount of the interfering light component based on representative values of the light receiving amounts in each of two measurement regions adjacent to and on one outer side of the target merging region including the target peak position identification region in the first light receiving signal.

4. The measuring device according to any one of claims 1 to 3, wherein, The representative value of the light receiving amount in each of the plurality of measurement regions in the first light receiving signal is an average value of the light receiving amounts indicated in the first light receiving signal and received by one or more light receiving elements included in the corresponding one measurement region among the plurality of measurement regions.

5. The measuring device according to any one of claims 1 to 3, wherein, At least one of the plurality of second boundaries is set at a central position between two adjacent first boundaries among the plurality of first boundaries.

6. The measuring device according to any one of claims 1 to 3, wherein, In a case where the threshold is controlled to change from a first threshold to a second threshold, when an estimated value of the second threshold is equal to or greater than an upper limit value, the signal processing unit sets the second threshold to the upper limit value.

7. The measuring device according to any one of claims 1 to 3, wherein, In a case where the threshold is controlled to change from a first threshold to a second threshold, when a difference between the first threshold and the estimated value of the second threshold is equal to or greater than an upper limit change amount, the signal processing unit sets the second threshold by adding the upper limit change amount to the first threshold.

8. The measuring device according to any one of claims 1 to 3, wherein, The signal processing unit is configured to: Identify at least one light-receiving element among the plurality of light-receiving elements, where a light-receiving amount indicated in the first light-receiving signal and received by the light-receiving unit of the at least one light-receiving element is equal to or greater than the threshold; And Measure the object based on the position of each of the at least one light-receiving element.

9. The measuring device according to any one of claims 1 to 3, wherein, The light-projecting unit is configured to project second projected light onto the object, the second projected light being different from the first projected light, wherein the light-receiving unit is configured to: generate a second light-receiving signal in response to receiving second reflected light obtained by the object reflecting or scattering the second projected light, and wherein the signal processing unit is configured to: Identify at least one light-receiving element among the plurality of light-receiving elements, where a light-receiving amount indicated in the second light-receiving signal and received by the light-receiving unit of the at least one light-receiving element is equal to or greater than the threshold; and Measure the object based on the position of each of the at least one light-receiving element.

10. A measuring method for optically measuring an object using a threshold, the measuring method comprising: The step of projecting first projected light onto the object; The step of generating a first light-receiving signal by a light-receiving unit including a plurality of light-receiving elements in response to receiving first reflected light obtained by the object reflecting or scattering the first projected light; And The step of processing the first light-receiving signal, wherein a light-receiving region of the plurality of light-receiving elements including the light-receiving unit is divided into a plurality of measurement regions defined by a plurality of first boundaries, the plurality of first boundaries divide the plurality of light-receiving elements into a plurality of groups corresponding to the plurality of measurement regions, each of the plurality of groups includes one or more light-receiving elements, and the light-receiving region is also divided into a plurality of peak position identification regions defined by a plurality of second boundaries different from the plurality of first boundaries, wherein each of the plurality of peak position identification regions includes at least a part of one measurement region and a part of another measurement region adjacent to the one measurement region, wherein the light-receiving region includes a plurality of merging regions, and each of the plurality of merging regions is formed by two adjacent measurement regions among the plurality of measurement regions, and wherein the step of processing the first light-receiving signal includes: The step of determining a target peak position identification region that is one of the plurality of peak position identification regions, the target peak position identification region including the position of the light-receiving element having the largest light-receiving amount in the first light-receiving signal; A step of estimating a light reception amount of an interfering light component in a target merging region that is one of the plurality of merging regions, the target merging region including the target peak position identification region, the estimation being based on representative values of light reception amounts in at least two measurement regions among the plurality of measurement regions that are outside the target merging region; and A step of controlling the threshold value based on the light reception amount of the interfering light component.

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