Measuring device and measuring method

Abstract

To provide a measurement device capable of reducing an influence of disturbance light and improving measurement accuracy of an object.SOLUTION: A measurement device for optically measuring an object using a threshold comprises a light projecting section, a light receiving section that receives reflected light obtained by reflecting or scattering projection light by the object to generate a light reception signal, and a signal processing section for processing the light reception signal. A light receiving area including a plurality of light receiving elements in the light receiving section is divided into a plurality of measurement regions and is also divided into a plurality of peak position identification regions. Each of the plurality of peak position identification regions includes a part of each of two measurement regions adjacent to each other. The signal processing section determines a peak position identification region including a position of a light receiving element where an amount of received light in the light reception signal is maximum, estimates an amount of received light of a disturbance light component on the basis of a representative value of an amount of received light in each of the plurality of measurement regions located outside the two measurement regions of which a part of each is included in the determined peak position identification region, and controls a threshold on the basis of the amount of received light of the disturbance light component.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

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

[0003] Specifically, when the amount of light received (light-receiving signal level) of each pixel of the image sensor is read out sequentially, the light-receiving signal level of each pixel is compared with a preset threshold, and the pixel range (see hatching) where the light-receiving signal level is equal to or greater than the threshold is set as the calculation range. Then, the peak position of the light-receiving signal level distribution (light-receiving waveform) is found within this set calculation range, and the found position is detected as the light-receiving center position.

[0004] An optical distance measuring device is known as a conventional measuring device. This optical distance measuring device includes a light-emitting element, an emitting optical system that focuses a light beam emitted from the light-emitting element to irradiate a spot light on a measurement object, a light-receiving optical system that focuses reflected light from the measurement object, a light-receiving element that detects the spot light from the measurement object focused by the light-receiving optical system, and a signal processing unit that processes a light-receiving signal from the light-receiving element. The light-receiving element is a line sensor or area sensor that detects the intensity distribution of the light reflected from the measurement object. The signal processing unit includes a distance calculation unit that calculates the spot position on the light-receiving element of the spot light focused by the light-receiving optical system and detects the distance from the spot position to the measurement object, and a correction calculation unit that detects the intensity distribution of cover-reflected light, which is light reflected by a translucent protective cover disposed between the light-emitting optical system, the light-receiving optical system, and the measurement object and detected by the light-receiving element via the light-receiving optical system, and corrects the distance calculation. The correction calculation unit calculates a correction coefficient corresponding to the intensity distribution of the cover reflected light from the intensity distribution of a partial area at least on one of the ends of the light receiving element, thereby correcting the intensity distribution of the spot light, and the distance calculation unit calculates the distance to the object to be measured based on the output of the correction calculation unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-224726 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the light receiving area of ​​the light receiving element has a central portion and both end portions (portions A and B). When a peak in the amount of received light exists near the boundary between the central portion and both end portions of the light receiving area 8, the light intensity distribution has a mountain shape (Gaussian shape), and the base of the light intensity distribution extends into the area (both end portions or the central portion) adjacent to the area (central portion or both end portions) where the peak in the amount of received light is located. Therefore, in Patent Document 1, light is reflected by the protective cover, which can reduce the accuracy of correction of the signal (noise, ambient light) detected by the light receiving element. As a result, the influence of ambient light remains, which can reduce the accuracy of measurement of the target object.

[0007] The present disclosure provides a measurement device and a measurement method that can reduce the influence of ambient light and improve the accuracy of measuring an object. [Means for solving the problem]

[0008] One aspect of the present disclosure is a measurement device that optically measures an object using a threshold value, the measurement device including: a light-projecting unit that projects a light projection onto the object; a light-receiving unit that has a plurality of light-receiving elements and receives reflected light that is the light projection light reflected or scattered by the object and generates a light-receiving signal; and a signal processing unit that processes the light-receiving signal; the plurality of light receiving elements are arranged in a row or on a two-dimensional plane, a light receiving area including the plurality of light receiving elements in the light receiving unit is divided into a plurality of measurement regions defined by a first boundary that collectively divides the plurality of light receiving elements, and into a plurality of peak position identification regions defined by a second boundary different from the first boundary, each of the plurality of peak position identification regions includes a portion of each of two adjacent measurement regions, and the two adjacent measurement regions form an integrated region, and the signal processing unit determines the peak position identification region that includes the position of the light receiving element with the largest amount of light received in the light receiving signal, estimates the amount of received light of ambient light components based on a representative value of the amount of received light in each of the plurality of measurement regions located outside the integrated region that includes the determined peak position identification region, and controls the threshold based on the amount of received light of the ambient light components.

[0009] One aspect of the present disclosure is a measurement method for optically measuring an object using a threshold value, the method comprising: a step of projecting a projected light onto the object; a step of receiving, by a light receiving unit having a plurality of light receiving elements, light reflected or scattered by the object from the projected light, thereby generating a light receiving signal; and a step of processing the light receiving signal, the plurality of light receiving elements are arranged in a row or on a two-dimensional plane, a light-receiving area including the plurality of light-receiving elements in the light-receiving unit is divided into a plurality of measurement regions defined by a first boundary that collectively divides the plurality of light-receiving elements, and into a plurality of peak position identification regions defined by a second boundary different from the first boundary, each of the plurality of peak position identification regions includes a portion of each of two adjacent measurement regions, and the two adjacent measurement regions form an integrated region, and the step of processing the light-receiving signal includes a step of determining the peak position identification region including the position of the light-receiving element with the largest amount of light received in the light-receiving signal, a step of estimating the amount of received light of an ambient light component based on a representative value of the amount of received light in each of the plurality of measurement regions located outside the integrated region that includes the determined peak position identification region, and a step of controlling the threshold based on the amount of received light of the ambient light component. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to reduce the influence of ambient light and improve the measurement accuracy of an object. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a conceptual diagram illustrating a situation in which a measurement device according to an embodiment of the present disclosure projects light onto an object and receives reflected light. [Figure 2] Block diagram showing an example of a measurement device [Figure 3] FIG. 1 is a diagram showing an example of a light receiving signal generated by a light receiving unit, a measurement region, a peak position identification region, and an integrated region; [Figure 4] 1 is a conceptual diagram illustrating an example of determining a peak position using a measuring device and an example of estimating the amount of received ambient light. [Figure 5]Graph illustrating another example of estimating the amount of ambient light components received by the measurement device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters or descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying 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 subject matter described in the claims.

[0013] FIG. 1 is a conceptual diagram illustrating a situation in which a measuring device according to an embodiment of the present disclosure projects a projected light onto an object and receives the reflected light. In the measuring device 50, a light projecting unit 1 projects a projected light L1 onto an object 10, and a light receiving unit 4 receives a reflected light L2 resulting from the projected light L1 being reflected or scattered by the object 10. The measuring device 50 optically measures the object 10 based on a light receiving 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 measuring sensor. The measuring device 50 may measure, for example, an absolute distance or a relative distance. The measuring device 50 may detect, for example, the presence or absence of displacement, such as unevenness, relative to a reference plane, or the amount of displacement.

[0014] 2 is a block diagram showing an example of a measurement device 50 according to an embodiment. The measurement 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 is composed of a light emitting element and the like. The light emitting element includes, for example, a laser diode.

[0015] The light receiving unit 4 has a plurality of light receiving elements. The light receiving elements are semiconductor light receiving elements including, for example, photodiodes or CMOS (Complementary Metal-Oxide-Semiconductor), and convert the optical signal of the received light into an electrical signal. The light receiving unit 4 receives reflected light L2, which is the projected light L1 reflected or scattered by the object 10, using the light receiving elements, and generates a light receiving signal. The light receiving unit 4 forms a line sensor in which the light receiving elements are arranged in a row on the x-axis, but may also be an area sensor in which the light receiving elements are arranged on a two-dimensional plane.

[0016] 2, projected light L1 projected from light projector 1 is incident on object 10, and reflected light L2 from object 10 is incident on light receiver 4 of measuring device 50. Reflected light L2 shown in the figure represents the optical axis detected by light receiver 4 as a result of multiple reflections.

[0017] Projection light L1 projected from the light projecting unit 1 is emitted via a light emitting lens 2. Most of the emitted luminous flux of the projection light L1 illuminates the target 10. Reflected light L2 from the target 10, which is located sufficiently far away, is collected by a 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 necessary to detect the intensity distribution S20 (see Figure 3) of the target 10. The light receiving area 8 is an area that includes multiple light receiving elements.

[0018] The signal processing unit 5 is configured by, for example, a processor. The processor executes programs stored in the memory unit 5M to realize various functions of the signal processing unit 5. The processor may include an MPU (Micro Processing Unit), a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). The processor 11 may be configured by various integrated circuits (for example, an LSI (Large Scale Integration) or an FPGA (Field Programmable Gate Array)). The signal processing unit 5 comprehensively controls each unit of the measuring device 50 and performs various processes. The signal processing unit 5 includes a threshold control unit 6 and a distance calculation unit 7.

[0019] The memory unit 5M includes a primary storage device (for example, a RAM (Random Access Memory) or a ROM (Read Only Memory)). The memory 13 may include a secondary storage device or a tertiary storage device, or may include a removable storage medium. The memory unit 5M stores various data or information. The memory unit 5M may hold information on the received light signal (information on the received light waveform indicating the received light signal). The information on the received light signal is used to control the threshold th for measuring the object 10.

[0020] The threshold control unit 6 controls the threshold th for measuring the object 10. The details of the threshold control unit 6 will be described later.

[0021] The distance calculation unit 7 measures the object 10 depending on which of the multiple light receiving elements of the light receiving unit 4 receives light. The distance calculation unit 7 may calculate the distance from the measurement device 50 to the object 10. Information on the detected distance for each light receiving element (cell distance information) may be stored in the memory unit 5M. The distance calculation unit 7 may calculate the distance to the object 10 based on the cell distance information. The distance calculation unit 7 identifies one or more light receiving elements for which the amount of light received in the light receiving signal S1 (see FIG. 3) received by the light receiving unit 4 is equal to or greater than a threshold value th. The distance calculation unit 7 may calculate the distance to the object 10 based on the positions of the identified light receiving elements.

[0022] Fig. 3 is a diagram showing an example of the light receiving signal S1 generated by the light receiving unit 4, the measurement region R1, the peak position identification region R2, and the integrated region TR. Fig. 4 is a conceptual diagram explaining an example of determining the peak position and estimating the amount of received ambient light by the measurement device 50. Fig. 4 is an enlarged view of the measurement regions R10 to R13 in the graph of Fig. 3.

[0023] 3 shows the light receiving signal S1 generated by the light receiving unit 4 based on the intensity distribution (reflected light profile) of the reflected light L2 received by the light receiving area 8 of the light receiving unit 4. The x-axis in FIG. 3 is the coordinate of the light receiving area 8, and each of the multiple light receiving elements arranged therein is assigned a number (light receiving element number). The multiple light receiving elements are arranged in the same direction as the light projecting unit 1 and light receiving unit 4 are arranged in FIG. 1.

[0024] The light receiving area 8 is divided into a plurality of measurement regions R1 defined by first boundaries B1 that collectively separate the plurality of light receiving elements. In Fig. 3, the measurement region R1 includes eight measurement regions R1 (R10 to R17).

[0025] FIG. 3 illustrates an example in which the light receiving unit 4 constitutes a line sensor. If the light receiving unit 4 constitutes an area sensor, multiple graphs of FIG. 3 are generated on a plane along an axis perpendicular to the x-axis.

[0026] The y-axis in Figure 3 represents the amount of light received by each light-receiving element (each light-receiving position) (e.g., a numerical value obtained by AD-converting a voltage). That is, it represents the amount of light received by the light-receiving unit 4, the light-receiving signal S1, generated based on the reflected light L2. The intensity distribution of the amount of light received by the light-receiving signal S1 is a shape obtained by adding the intensity distribution S20 of the amount of light received by the object 10 to the intensity distribution S10 of the amount of light received, which increases in either direction along the x-axis (toward the left in this example). In Figure 3, the intensity distribution S10 slopes upward to the left, i.e., the value (amount of light received) increases as the amount of light received by the light-receiving element with the smaller light-receiving element number increases. This phenomenon is caused by the effect of ambient light, and is a common phenomenon observed in measurement devices. In other words, the intensity distribution S10 corresponds to the amount of light received by the ambient light component. Furthermore, the intensity distribution S20 has a shape with a predetermined peak that conforms to a so-called Gaussian distribution, and this peak corresponds to the reflected light L2 from the object 10.

[0027] The disturbance light appearing in the intensity distribution S10 includes, for example, ambient light. Ambient light includes light such as sunlight or lighting around the measurement device 50. When the disturbance light is reflected or scattered by the object 10, it may be received by the light receiving unit 4 as a disturbance light component that is part of the components of the reflected light L2.

[0028] In FIG. 3, the intensity distribution S20 has a peak in the measurement region R12. The threshold controller 6 processes the light-receiving signal S1 and determines that the reflected light L2 from the object 10 is received by the measurement region R12. The distance calculator 7 calculates the distance to the object 10 based on the measurement region R1 that received the reflected light L2. In this case, the distance calculator 7 compares the amount of light received by each light-receiving element with the threshold value th set by the threshold controller 6 and sets only light-receiving elements whose amount of light received is equal to or greater than the threshold value th within the distance calculation range. The distance calculator 7 calculates the peak position of the intensity distribution S20 within the set distance calculation range and detects this position as the light-receiving center position. This allows the measurement device 50 to reduce calculation errors. The distance calculator 7 may derive the distance corresponding to the detected light-receiving position based on the cell distance information.

[0029] 3, the dark level is preset to the amount of received light that the light receiving unit 4 always generates even if it does not detect light. The dark level is set to a predetermined value, for example, when the measurement device 50 is started up, and is stored in the memory unit 5M. For example, when the measurement device 50 is started up, the signal processing unit 5 sets an initial setting threshold th1 and stores it in the memory unit 5M. The initial setting threshold th1 may be preset to a generally applicable amount of received light. When the initial setting threshold th1 is set, the distance calculation unit 7 only targets light receiving elements that detect an amount of received light greater than the initial setting threshold th1 for calculation of the measurement of the object 10.

[0030] Here, the environment of the measurement device 50 varies widely, and the initial setting threshold th1 may not be appropriate for the amount of received light depending on the situation. Therefore, the threshold control unit 6 estimates the amount of received light of the disturbance light component and controls the threshold th based on the estimated amount of received light of the disturbance light component. In the example of FIG. 3, the initial setting threshold th1 is too small, and all light-receiving elements are subject to the calculation by the distance calculation unit 7 to derive the light-receiving center position. Therefore, the threshold control unit 6 determines the intensity distribution S10 and the intensity distribution S20 and determines the estimated threshold th2 corresponding to the amount of received light of the light-receiving signal S1 (i.e., the received light waveform). In other words, the threshold control unit 6 changes the initial setting threshold th1 to the estimated threshold th2 (arrow C2 in FIG. 3). The measurement device 50 optically measures the object 10 using the estimated threshold th2, thereby reducing calculation errors.

[0031] For example, if there are many disturbance light components, that is, if the measurement device 50 is placed in an environment brighter than the environment corresponding to the initial setting threshold th1, the estimated threshold th2 is changed to be larger than the initial setting threshold th1. If there are few disturbance light components, that is, if the measurement device 50 is placed in an environment darker than the environment corresponding to the initial setting threshold th1, the estimated threshold th2 is changed to be smaller than the initial setting threshold th1. Furthermore, the threshold th may be changed based on temperature as well as brightness.

[0032] Based on the amount of light received at each light receiving element indicated by the light receiving signal S1, the threshold control unit 6 determines the peak position of the light receiving signal S1, i.e., the position of the light receiving element where the amount of light received is maximum (maximum light receiving position), and the peak position identification region R2 (peak position identification region R21 in this example) to which the maximum light receiving position belongs.

[0033] In this embodiment, the light receiving area 8 is divided into two types of regions. Specifically, the light receiving area 8 is divided into a plurality of measurement regions R1. The light receiving area 8 is also divided into a plurality of peak position identification regions R2 for identifying peak positions of the received light signal S1. The plurality of peak position identification regions R2 are defined and separated by a second boundary B2 that is different from the first boundary B1 that defines the measurement region R1. Once the measurement region R1 is defined, the peak position identification region R2 is defined. For example, the peak position identification region R2 is defined so that the second boundary B2 is the center position of two adjacent first boundaries B1 that define the measurement region R1.

[0034] The second boundary B2 is set, for example, at the center position on the x-axis of each of the measurement regions R11 to R16, that is, the center position in the arrangement direction of the light receiving elements of the measurement regions R11 to R16. In other words, the second boundary B2 is set, for example, at the center position between two adjacent first boundaries B1. However, the position of the second boundary B2 is not limited to this example, as long as it does not overlap with the first boundary B1.

[0035] In FIG. 3, the peak position specifying region R2 includes seven peak position specifying regions R2 (R21 to R26) as follows.

[0036] Each of the multiple peak position identification regions R2 includes a portion of each of the two adjacent measurement regions R1. For example, the peak position identification region R21 includes a portion (right half) of the measurement region R11 and a portion (left half) of the measurement region R12. The two adjacent measurement regions R1 then form an integrated region TR in which the two measurement regions R1 are integrated.

[0037] In this embodiment, the integrated area is represented as TRxy, where x is the suffix of one of the two adjacent measurement areas R1 (the one with the smaller suffix), and y is the suffix of the other of the two adjacent measurement areas R1 (the one with the larger suffix). For example, the integrated area TR including the measurement areas R11 and R12 is the integrated area TR12. Similarly, the relationship between the integrated area TR and the measurement area R1 is, for example, as follows:

[0038] Integrated area TR01: Measurement area R10, R11 Integrated area TR12: Measurement area R11, R12 Integrated area TR23: Measurement area R12, R13 Integrated area TR34: Measurement area R13, R14 Integrated area TR45: Measurement area R14, R15 Integrated area TR56: Measurement area R15, R16 Integrated area TR67: Measurement area R16, R17

[0039] The threshold control unit 6 determines a peak position identification region R21 that includes the maximum light-receiving position of the light-receiving signal S1. The maximum light-receiving position is the position of the light-receiving element where the amount of light received by the light-receiving signal S1 is the maximum. In FIG. 3, the threshold control unit 6 determines that the peak position identification region R21 includes the maximum light-receiving position.

[0040] The threshold control unit 6 determines that the peak position identification region R21, which includes the maximum light reception position, includes a portion (left half) of the measurement regions R11 and R12, and is therefore included in the integrated region TR12. The threshold control unit 6 calculates a representative value of the amount of received light in each of the measurement regions R1 located outside the peak position identification region R21, i.e., outside the integrated region TR corresponding to the peak position identification region R21. In this example, the threshold control unit 6 calculates a representative value of the amount of received light in each of the measurement regions R10 and R13 located outside the peak position identification region R21. Note that because the first boundary B1 and the second boundary B2 do not overlap, the measurement region R10 and the measurement region R13 are adjacent to the outside of the integrated region TR12 corresponding to the peak position identification region R21.

[0041] 3, the representative value of the amount of received light in the measurement region R10 is the amount of received light A0. The representative value of the amount of received light in the measurement region R13 is the amount of received light A3. For example, the threshold control unit 6 calculates the amount of received light A in the integrated region corresponding to the peak position identification region R21 including the maximum light reception position (for example, the center position of the integrated region TR on the x-axis) based on the amount of received light A0 in the measurement region R10 and the amount of received light A3 in the measurement region R13. T12 Calculate the amount of light received A T12 is a representative value of the amount of received light in the integrated region TR. T12 can be calculated as a value on the line D, for example, based on the line D connecting the amounts of received light A0 and A3, which are representative values.

[0042] The threshold control unit 6 calculates the offset amount of received light in the measurement region R1 by subtracting the amount of received light at the dark level from the representative value of the amount of received light in the measurement region R1. This calculation of the offset amount of received light is the same not only for the measurement region R1 but also for the integrated region TR. Therefore, the threshold control unit 6 calculates the amount of received light A in the integrated region TR12. T12 The offset amount of received light in the measurement region R1 is calculated by subtracting the amount of received light at the dark level from the measured value.

[0043] In this way, the threshold control unit 6 calculates the offset amount of received light of the integrated region TR12 based on the amounts of received light A0 and A3 as representative values ​​in the measurement regions R10 and R13, respectively. The threshold control unit 6 determines the estimated threshold th2 based on the initial setting threshold th1 and the offset amount of received light of the integrated region TR12. In this case, the threshold control unit 6 may determine the estimated threshold th2 by adding the offset amount of received light of the integrated region TR12 to the initial setting threshold th1.

[0044] Calculation of the offset value of the integrated region TR12 corresponding to the peak position identification region R21 including the maximum light-receiving position corresponds to estimation of the amount of disturbance light components received in the integrated region TR12. The threshold control unit 6 then controls the threshold th based on the offset amount of received light corresponding to the estimated amount of disturbance light components received. This allows the measurement device 50 to appropriately set the threshold th and appropriately limit the distance measurement calculation range of the light-receiving center position for measurement of the target 10.

[0045] In this embodiment, even if the maximum light receiving position of the light receiving signal S1 is near the first boundary B1, which is the boundary between two measurement regions R12, it does not necessarily mean that the position is near the first boundary B1 (the boundary between the measurement regions R12 and R13), which is the outer edge of the integrated region TR12 corresponding to the peak position identification region R2 including the maximum light receiving position. That is, even if the maximum light receiving position is near the boundary (first boundary B1) between two measurement regions R1, it will be located outside the boundary (outer edge) of the integrated region TR including the maximum light receiving position (near the center of the integrated region TR). This prevents the base portion of the light receiving signal S1, where the amount of received light decreases from the maximum light receiving position, from extending outside the integrated region TR including the maximum light receiving position with a large value. Therefore, the measurement device 50 can prevent the original signal component of the light receiving signal S1 from entering the amount of received light from which the offset amount of received light is derived, thereby enabling the offset amount of received light to be derived with high accuracy. This allows the measurement device 50 to appropriately determine the threshold value th.

[0046] Furthermore, even if the maximum light-receiving position of the light-receiving signal S1 is near the boundary (second boundary B2) between two adjacent peak position identification regions R2, the outer edge (first boundary B1) of the integrated region TR corresponding to the peak position identification region R2 will be located outside the position of this second boundary B2. Therefore, the base portion where the amount of received light decreases from the maximum light-receiving position of the light-receiving signal S1 can be prevented from entering the outside of the integrated region TR including the maximum light-receiving position with a large value. Therefore, the measurement device 50 can prevent the original signal component of the light-receiving signal S1 from entering the amount of received light from which the offset amount of received light is derived, and can therefore derive the offset amount of received light with high accuracy. Therefore, the measurement device 50 can appropriately determine the threshold value th.

[0047] 3 also includes a graph illustrating an example of estimation of the amount of disturbance light components received by the measurement device 50. The threshold control unit 6 may estimate the amount of disturbance light components received based on a representative value of the amount of light received by the light-receiving signal S1 in each of the two measurement regions R10, R13 adjacent to the outside of the integrated region TR12 corresponding to the determined peak position identification region R21. In this case, the threshold control unit 6 may calculate, for each measurement region R1, the average value of the amount of light received by each of the multiple light-receiving elements included in the measurement region R1 as the representative value of the amount of light received by the light-receiving signal S1. Note that the representative value of the amount of received light may be a value other than this average value (e.g., a maximum value or a minimum value).

[0048] When the threshold control unit 6 uses the average value of the amount of received light for each measurement region R1 as a representative value of the amount of received light, it may estimate the offset amount of received light of the integrated region TR including the position of maximum light reception according to Table 1 below. For example, as shown in FIG. 3, when the position of maximum light reception is included in the peak position identification region R21, the integrated region TR12 is identified corresponding to the peak position identification region R21. The threshold control unit 6 calculates the offset amount of received light of the integrated region TR12 according to, for example, (A0+A3) / 2. Furthermore, when the position of maximum light reception is included in the peak position identification region R22, the integrated region TR23 is identified corresponding to the peak position identification region R22. The threshold control unit 6 calculates the offset amount of received light of the integrated region TR23 according to, for example, (A1+A4) / 2. Note that here, the amount of received light A n is a representative value (for example, an average value) of the amount of light received in the measurement region R1n.

[0049] 5 is a graph illustrating another example of estimating the amount of received light of disturbance light components by the measurement device 50. In the example of FIG. 5, the peak position (maximum light-receiving position) of the intensity distribution S20 is located in the peak position identification region R20. In this example, there is no adjacent measurement region R1 on the left side (smaller side of the x-axis) of the integrated region TR01 corresponding to the peak position identification region R20. Therefore, the threshold control unit 6 may estimate the amount of received light of disturbance light components based on the amounts of received light A2 and A3 as representative values ​​of the received light signal S1 in two adjacent measurement regions R12 and R13 on one side (e.g., the right side, larger side of the x-axis) of the integrated region TR01.

[0050] 5, when the maximum light receiving position is included in peak position identification region R21, integrated region TR01 is identified corresponding to peak position identification region R20. The threshold control unit 6 calculates the offset amount of received light of integrated region TR01, for example, according to (5A2-3A3) / 2. As a result, even if peak position identification region R2 including the maximum light receiving position or integrated region TR is located at the edge of the light receiving area 8, the measurement device 50 can estimate the offset amount of received light of integrated region TR using the external division point and determine an appropriate threshold th.

[0051] The threshold control unit 6 may estimate the offset amount of received light of the integrated area TR based on a representative value of the amount of received light of each of multiple measurement areas R1 that are not adjacent to the integrated area TR including the maximum light receiving position. The threshold control unit 6 may also estimate the offset amount of received light of the integrated area TR based on a representative value of the amount of received light of each of three or more measurement areas R1 that are outside the integrated area TR including the maximum light receiving position. When three or more amounts of received light are available, the threshold control unit 6 may estimate the offset amount of received light of the integrated area TR according to various known approximation methods, rather than a linear approximation method.

[0052] Next, variations in threshold control will be described.

[0053] The threshold control unit 6 may control the threshold th so that it does not exceed its upper limit. The amount of light received by the light receiving unit 4 can be adjusted by adjusting the projection time of the projected light L1 by the light projecting unit 1. The upper limit of the threshold th is determined taking into account the amount of light that can be received by the light receiving unit 4. The light projecting unit 1 may adjust the amount of light that can be projected so that it is equal to or greater than the upper limit of the threshold th and equal to or less than the upper limit of the amount of light that can be received. The upper limit of the threshold th may be stored in the memory unit 5M.

[0054] For example, when controlling the threshold th to change it from the initial setting threshold th1 to the estimated threshold th2, if the planned value of the estimated threshold th2 is equal to or greater than the upper limit, the threshold control unit 6 may set the estimated threshold th2 to the upper limit. The planned value of the estimated threshold th2 is the initial estimated threshold th2 calculated by the threshold control unit 6 by taking into account the offset amount of received light in the integrated region TR without taking into account the upper limit. Therefore, the threshold control unit 6 can prevent the estimated threshold th2 from becoming excessively large.

[0055] Furthermore, the threshold control unit 6 may control the amount of change in the threshold th so that it does not exceed the upper limit of change. For example, when controlling the threshold th to change from the initially set threshold th1 to the estimated threshold th2, if the difference between the initially set threshold th1 and the expected value of the estimated threshold th2 is greater than a predetermined value, that is, if the amount of change in the threshold th is greater than the upper limit of change, the threshold control unit 6 may add the upper limit of change to the initially set threshold th1 to determine the estimated threshold th2. Thus, the threshold control unit 6 can prevent the estimated threshold th2 from changing suddenly, which in turn prevents the measurement results of the object 10 using the estimated threshold th2 from changing suddenly.

[0056] The timing at which the threshold control unit 6 performs threshold control is arbitrary. For example, the timing of threshold control and the timing of measuring the object 10 may be the same. For example, the threshold control unit 6 may control the threshold th every time the object 10 is measured. The threshold control unit 6 may also control the threshold th every time the light receiving signal S1 (light receiving waveform) is acquired.

[0057] Furthermore, the timing of threshold control and the timing of measuring the object 10 may be different. For example, the light projecting unit 1 may project a measurement light L11 different from that used for threshold control onto the object 10, and the light receiving unit 4 may receive a measurement reflected light L21 resulting from reflection or scattering of the projected light L11 by the object 10, and generate a measurement light receiving signal S11 different from that used for threshold control. The distance calculation unit 7 may identify a light receiving element whose received light amount of the light receiving signal S11 received by the light receiving unit 4 is equal to or greater than the threshold th controlled by the threshold control unit 6, and measure the object 10 based on the position of the identified light receiving element. That is, the distance calculation unit 7 may measure the object 10 using the measurement light projecting light L11 and reflected light L21, separate from the projected light L1 and reflected light L2 used for threshold control.

[0058] In this way, the measurement device 50 of this embodiment uses a peak position identification region R2 that is different from the region (measurement region R1) used during actual measurement (e.g., during distance measurement) to identify the peak position identification region R2 that includes the maximum light reception position. The measurement device 50 identifies an integrated region TR corresponding to the identified peak position identification region R2, calculates the offset amount of received light for the integrated region TR, and estimates ambient light at, for example, the center position of the integrated region TR. The estimated ambient light corresponds to a variable dark level. The measurement device 50 can adjust the threshold value th according to the estimated ambient light.

[0059] For example, suppose the darkness level fluctuates to a larger value overall. In this case, the initial setting threshold th1 becomes smaller relative to the darkness level, and the number of light-receiving elements that receive a light amount greater than the initial setting threshold th1 increases. That is, reflected light L2 with a light amount equal to or greater than the initial setting threshold th1 is received not only around the peak position but also over a wide area of ​​the light-receiving area 8. In such a case, the distance calculation unit 7 calculates the light-receiving center position over a wide area of ​​the light-receiving area 8, which may result in a decrease in measurement accuracy of the object 10. In response to this, the measurement device 50 changes the initial setting threshold th1 to the estimated threshold th2 based on the estimation result of ambient light that fluctuates in response to the darkness level. This reduces the number of light-receiving elements in the light-receiving area 8 that receive a light amount equal to or greater than the estimated threshold th2, and the light-receiving element receives reflected light L2 with a light amount equal to or greater than the estimated threshold th2 only around the peak position in the light-receiving area 8. Therefore, the measurement device 50 can suppress a decrease in measurement accuracy of the object 10.

[0060] Furthermore, the measurement device 50 derives the offset amount of received light for the integrated area TR using the amount of received light in the measurement area R1 outside the integrated area TR where the maximum light reception position is located, and does not use the amount of received light within the integrated area TR to derive the offset amount of received light for the integrated area TR. The integrated area TR receives a large amount of signal components of reflected light L2, which is the light projected from or scattered by the projected light L1 (i.e., components other than ambient light that are the intended target components). Therefore, the measurement device 50 can derive the offset amount of received light for the integrated area TR using the amount of received light in the measurement area R1, which excludes the intended target components and contains many ambient light components, thereby improving the estimation accuracy of ambient light.

[0061] In this embodiment, the offset light-receiving amount is mainly a positive value, but this is not limited to this. The offset light-receiving amount of ambient light may also be a negative value. When the offset light-receiving amount of ambient light is a negative value, the estimated threshold value th2 is changed to be smaller than the initial setting threshold value th1. The threshold control unit 6 may estimate ambient light at a position other than the center of the integrated region TR, for example, may estimate ambient light at the maximum light-receiving position.

[0062] As described above, the measuring device 50 of the above embodiment optically measures the object 10 using a threshold value. The measuring device 50 includes a light projecting unit 1 that projects a projected light L1 onto the object 10, a light receiving unit 4 having a plurality of light receiving elements that receives reflected light L2 resulting from the projected light L1 being reflected or scattered by the object 10 and generates a received light signal S1, and a signal processing unit 5 that processes the received light signal S1. A light receiving area 8 including the plurality of light receiving elements in the light receiving unit 4 is divided into a plurality of measurement regions R1 defined by a first boundary B1 that collectively separates the plurality of light receiving elements, and into a plurality of peak position identifying regions R2 defined by a second boundary B2 different from the first boundary B1. Each of the plurality of peak position identifying regions R2 includes a portion of each of two adjacent measurement regions R1. The two adjacent measurement regions R1 form an integrated region TR. The signal processing unit 5 determines a peak position identification region R2 that includes the position of the light receiving element where the amount of light received in the light receiving signal S1 is maximum (maximum light receiving position).The signal processing unit 5 estimates the amount of received light of the disturbance light component in the integrated region TR (offset received light amount) based on a representative value of the amount of received light in each of multiple measurement regions R1 located outside the integrated region TR that includes the determined peak position identification region R2.The signal processing unit 5 controls the threshold value th based on the amount of received light of the disturbance light component.

[0063] As a result, the measurement device 50 can control the threshold value th by taking into consideration the peak position identification region R2 for identifying the peak position of the received light signal S1 and the integrated region TR, in addition to the measurement region R1 used to measure the object 10. In this case, even if a peak position (maximum light reception position) is located at the boundary edge of the measurement region R1, the measurement device 50 selects the integrated region TR so that the peak position is located near the center of the integrated region TR, even if the peak position in the measurement region R1 is located at the boundary edge of the measurement region R1. Therefore, the base portion of the received light waveform representing the received light signal S1 does not extend into the outer region adjacent to the integrated region TR. Therefore, the signal component is located within the integrated region TR, and the disturbance light component other than the signal component is located outside the integrated region TR. By using the amount of received light outside the integrated region TR, the measurement device 50 can accurately estimate the received light level of disturbance light and appropriately determine the threshold value th for measuring the object 10. Therefore, the measuring device 50 can reduce the influence of ambient light and improve the accuracy of measuring the object.

[0064] In addition, the signal processing unit 5 may estimate the amount of received light of the ambient light component based on a representative value of the amount of received light of the light receiving signal S1 in each of two measurement regions R1 adjacent to both outside of the integrated region TR including the determined peak position identification region R2.

[0065] As a result, the measurement device 20 estimates the amount of received disturbance light components using the amount of received light in the measurement region R1, which contains almost no signal components that are originally desired to be acquired and has a large amount of disturbance light components, thereby enabling high-accuracy estimation of the disturbance light in the integrated region TR.

[0066] In addition, the signal processing unit 5 may estimate the amount of received light of the ambient light component based on a representative value of the amount of received light of the light receiving signal S1 in each of two measurement regions R1 adjacent to one outside of the integrated region TR including the determined peak position identification region R2.

[0067] As a result, even if the peak position identification region R2 including the maximum light reception position or the integrated region TR is located at the edge of the light reception area 8, the measurement device 50 can estimate the offset light reception amount of the integrated region TR using the external division point and determine an appropriate threshold value th.

[0068] The representative value of the amount of light received by the light receiving signal S1 may be the average value of the amount of light received by each of the light receiving elements included in the measurement region R1, thereby allowing an appropriate value of the amount of light received that represents the measurement region R1 to be obtained.

[0069] The second boundary B2 may be set at the center position between two adjacent first boundaries B1.

[0070] This allows the peak position identification region R2 to include half of each of the two measurement regions R1. Therefore, the positional relationship between the measurement region R1, peak position identification region R2, and integrated region TR is symmetrical. Therefore, the measurement device 50 can prevent ambient light estimation in the integrated region TR from being performed based on the amount of received light at a position biased toward the larger or smaller side of the x-axis of the light-receiving area 8, thereby improving the estimation accuracy of ambient light.

[0071] In addition, when the signal processing unit 5 controls the threshold to change from the initial setting threshold th1 (an example of a first threshold) to the estimated threshold th2 (an example of a second threshold), if the planned value of the estimated threshold th2 is equal to or greater than a predetermined upper limit value, the signal processing unit 5 may set the estimated threshold th2 to the upper limit value.

[0072] This allows the measurement device 50 to take into account the characteristics of the light projector 1 or the light receiver 4, for example, and to prevent the estimated threshold value th2 from becoming excessively large.

[0073] In addition, when the signal processing unit 5 controls the threshold to change from the initial setting threshold th1 to the estimated threshold th2, if the difference between the initial setting threshold th1 and the planned value of the estimated threshold th2 is equal to or greater than a predetermined upper limit change amount, the signal processing unit 5 may set the estimated threshold th2 by adding the upper limit change amount to the initial setting threshold th1.

[0074] This allows the measurement device 50 to prevent the estimated threshold th2 from changing suddenly, and the measurement results of the object 10 using the estimated threshold th2 from changing suddenly.

[0075] Furthermore, the signal processing unit 5 may identify a light receiving element whose received light amount of the light receiving signal S1 received by the light receiving unit 4 is equal to or greater than a threshold, and measure the target object 10 based on the position of the identified light receiving element.

[0076] This allows the measurement device 50 to determine the threshold value th that takes into account the disturbance light component at the same timing as the measurement timing, thereby enabling the measurement device 50 to measure the object 10 with high accuracy in a short time.

[0077] Furthermore, the light projecting unit 1 may project another projected light onto the object 10. The light receiving unit 4 may receive another reflected light that is the other projected light reflected or scattered by the object 10, and generate another received light signal. The signal processing unit 5 may identify a light receiving element whose received light amount of the other received light signal received by the light receiving unit 4 is equal to or greater than a threshold value th, and measure the object 10 based on the position of the identified light receiving element.

[0078] This allows the measurement device 50 to determine the threshold value th that takes into account the disturbance light component at a timing different from the measurement timing. Therefore, the measurement device 50 can measure the object 10 by determining the threshold value th at a different timing and reducing the processing load during measurement.

[0079] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0080] In the above embodiments, a processor such as a CPU may be physically configured in any manner. Furthermore, if a programmable processor is used, the processing content can be changed by changing the program, thereby increasing the degree of freedom in processor design. The processor may be configured as a single semiconductor chip, or may be physically configured as multiple semiconductor chips. When configured as multiple semiconductor chips, each control in the above embodiments may be realized by a separate semiconductor chip. In this case, these multiple semiconductor chips can be considered to constitute a single processor. Furthermore, the processor may be configured as a semiconductor chip and a component (such as a capacitor) having a different function. Furthermore, a single semiconductor chip may be configured to realize both the function of the processor and other functions. Furthermore, the functions of multiple processors may be realized by a single processor. [Industrial Applicability]

[0081] The present disclosure is useful for a measurement device and a measurement method that can reduce the influence of ambient light and improve the measurement accuracy of an object. [Explanation of symbols]

[0082] 1 Light emitter 2. Light-emitting lens 3. Receiving lens 4 Light receiving section 5. Signal Processing Section 5M storage section 6 Threshold control section 7 Distance calculation section 8 Light receiving area 10 Object 50 Measuring Equipment R10~R17 Measurement area R20~R26 Peak position identification area TR integration area th1 Initial setting threshold th2 Estimated threshold

Claims

1. A measurement device for optically measuring an object using a threshold, comprising: a light projection unit that projects a light onto the target; a light receiving unit having a plurality of light receiving elements, receiving reflected light resulting from reflection or scattering of the projected light by the object, and generating a light receiving signal; a signal processing unit that processes the received light signal; Equipped with the plurality of light receiving elements are arranged in a row or on a two-dimensional plane, a light receiving area including the plurality of light receiving elements in the light receiving unit is divided into a plurality of measurement regions defined by a first boundary that collectively divides the plurality of light receiving elements, and is also divided into a plurality of peak position identification regions defined by a second boundary different from the first boundary; each of the plurality of peak position identification regions includes a portion of each of two of the measurement regions adjacent to each other; the two adjacent measurement regions form an integrated region; The signal processing unit determining the peak position identifying region including the position of the light receiving element where the amount of light received in the light receiving signal is maximum; estimating the amount of received light of the disturbance light component in the integrated area based on a representative value of the amount of received light in each of the plurality of measurement areas located outside the integrated area including the determined peak position identification area; controlling the threshold value based on the amount of received disturbance light component; Measuring equipment.

2. the signal processing unit estimates the amount of received light of the disturbance light component based on a representative value of the amount of received light of the light reception signal in each of the two measurement regions adjacent to both outside of the integrated region including the determined peak position identification region. The measuring device according to claim 1 .

3. the signal processing unit estimates the amount of received light of the disturbance light component based on a representative value of the amount of received light of the light reception signal in each of the two measurement regions adjacent to the outside of one of the integrated regions including the determined peak position identification region; The measuring device according to claim 1 .

4. the representative value of the amount of light received in the light receiving signal is an average value of the amount of light received in the light receiving signal received by each of a plurality of light receiving elements included in the measurement area; The measuring device according to any one of claims 1 to 3.

5. The second boundary is set at a center position between two adjacent first boundaries. The measuring device according to any one of claims 1 to 4.

6. When the signal processing unit controls the threshold to change from a first threshold to a second threshold, if a planned value of the second threshold is equal to or greater than a predetermined upper limit value, the signal processing unit sets the second threshold to the upper limit value. The measuring device according to any one of claims 1 to 5.

7. When the signal processing unit controls the threshold to change from a first threshold to a second threshold, if a difference between the first threshold and an expected value of the second threshold is equal to or greater than a predetermined upper limit change amount, the signal processing unit sets the second threshold by adding the upper limit change amount to the first threshold. The measuring device according to any one of claims 1 to 5.

8. The signal processing unit Identifying a light receiving element in which the amount of light received by the light receiving unit is equal to or greater than the threshold value; measuring the object based on the identified position of the light receiving element; The measuring device according to any one of claims 1 to 7.

9. The light projecting unit projects another light onto the object, the light receiving unit receives another reflected light that is the other projected light reflected or scattered by the object, and generates another light receiving signal; the signal processing unit identifies a light receiving element in which the amount of light received by the light receiving unit is equal to or greater than the threshold value; measuring the object based on the identified position of the light receiving element; The measuring device according to any one of claims 1 to 7.

10. A measurement method for optically measuring an object using a threshold, comprising: projecting a light onto the object; a step in which a light receiving unit having a plurality of light receiving elements receives reflected light resulting from reflection or scattering of the projected light by the object, and generates a light receiving signal; processing the received light signal; and the plurality of light receiving elements are arranged in a row or on a two-dimensional plane, a light receiving area including the plurality of light receiving elements in the light receiving unit is divided into a plurality of measurement regions defined by a first boundary that collectively divides the plurality of light receiving elements, and is also divided into a plurality of peak position identification regions defined by a second boundary different from the first boundary; each of the plurality of peak position identification regions includes a portion of each of two of the measurement regions adjacent to each other; the two adjacent measurement regions form an integrated region; The step of processing the received light signal includes: determining the peak position identifying region including the position of the light receiving element where the amount of light received by the light receiving signal is maximum; a step of estimating the amount of received light of the disturbance light component in the integrated area based on a representative value of the amount of received light in each of a plurality of measurement areas located outside the integrated area including the determined peak position identification area; and controlling the threshold value based on the amount of received disturbance light component. Measurement method.

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