JP2023113553A - Distance measuring device, automatic door system, opening-closing system, and distance measurement method - Google Patents

Abstract

To reduce a processing amount for distance measurement.SOLUTION: A detecting device (30) includes: a light-emitting element (31); and an image sensor (33) in which a plurality of pixel parts (33A) including a light-receiving element (33Aa) are two-dimensionally arranged. The image sensor (33) includes a position output section configured to, in a case where an amount of light received of the light-receiving element (33Aa) is greater than a first threshold value, output a position in the image sensor (33) of the pixel part (33A) of the light-receiving element (33Aa). The detecting device (30) further includes: a position determining section (34B) configured to determine whether the position is located on a reflection trajectory, the reflection trajectory being a line connecting, on the image sensor (33), points at which a reflected beam of an irradiated beam reflected by a physical object forms an image on the image sensor (33) and which are obtained as a distance from the physical object is changed; and a distance deriving section (34C) configured to derive, with use of the relationship between the position and the distance from the physical object, a distance to the physical object when the position is on the reflection trajectory.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a distance measuring device and the like that measures a distance to an object.

Distance measuring devices that measure the distance to an object are widely used. Such a distance measuring device is sometimes required to shorten the time until distance measurement as much as possible. In order to solve such problems, Patent Documents 1 and 2 disclose techniques for reducing the amount of processing (computational amount) for distance measurement.

Japanese Patent Publication No. 2021-518535 Japanese Patent Publication No. 2021-522730

However, the techniques of Patent Documents 1 and 2 have room for further improvement.

An object of one aspect of the present disclosure is to implement a distance measurement device and a distance measurement method capable of reducing the amount of processing for distance measurement.

In order to solve the above problems, a distance measuring device according to an aspect of the present disclosure includes one or more light emitting elements, and an image sensor in which a plurality of pixel units including the light receiving elements are two-dimensionally arranged. the image sensor includes a position output unit that outputs a position of the pixel unit including the light receiving element in the image sensor when the amount of light received by the light receiving element exceeds a first threshold; When a reflection locus is defined as a line connecting points on the image sensor where an irradiation beam reflected by an object is imaged on the image sensor while varying the distance from the object, the position is on the reflection locus, and if the position is on the reflection locus, the relationship between the position and the distance to the object is used to determine and a distance derivation unit that derives the distance.

According to the above configuration, the distance derivation process is performed only for the pixel portions for which the amount of received light exceeds the first threshold. Therefore, the amount of processing for distance derivation can be reduced.

Furthermore, the distance derivation process is performed only when the position of the light receiving element among the light receiving elements whose light receiving amount exceeds the first threshold is on the reflection locus. Therefore, since it is not necessary to scan the entire image sensor, the amount of processing for distance derivation can be further reduced.

In the distance measuring device according to an aspect of the present disclosure, each of the plurality of pixel units includes an event generating unit that generates an event when the amount of light received by each light receiving element exceeds the first threshold, The position output section may output the position in the image sensor of the pixel section where the event generation section generated the event.

In the distance measuring device according to one aspect of the present disclosure, the first threshold and the second threshold are set as a ratio to a reference amount of received light, and the reference amount of received light is set to the amount of received light after the occurrence of the event. The amount of received light indicated by the first threshold is larger than the reference amount of received light by a first percentage of the reference amount of received light, and the amount of received light indicated by the second threshold is higher than the reference amount of received light. The event generation unit generates the event when the amount of light received by the light receiving element is less than the second threshold in addition to when the amount of light received by the light receiving element exceeds the first threshold. good.

According to the above configuration, an event can be generated when the reflected beam no longer forms an image and the amount of light received by the light-receiving element becomes the amount of light received before the occurrence of the event.

In the distance measuring device according to one aspect of the present disclosure, the event generation unit generates an event that can identify whether the amount of received light exceeds the first threshold or falls below the second threshold. good.

According to the above configuration, it is possible to recognize whether an event has occurred due to a large amount of received light or a small amount of received light.

In the distance measuring device according to one aspect of the present disclosure, the absolute value of the first ratio for setting the first threshold is greater than the absolute value of the second ratio for setting the second threshold, a same-pixel event determination unit that determines whether the amount of received light in the same light-receiving element falls below the second threshold after exceeding the first threshold within a predetermined time; The same-pixel event determination unit determines that the amount of received light in the same light-receiving element exceeds the first threshold value and then falls below the second threshold value. It may be determined whether it is on the top or not.

According to the above configuration, it can be confirmed whether or not the light receiving element whose light receiving amount exceeds the first threshold is the same as the light receiving element whose light receiving amount is less than the second threshold. Therefore, it can be confirmed by the irradiation beam that the amount of light received by the light receiving element exceeds the first threshold value, and the position of the pixel portion where the event has occurred by the irradiation beam can be accurately recognized. In addition, since processing is performed only when an event occurs due to stopping irradiation of the irradiation beam, the amount of processing can be reduced.

In the distance measuring device according to one aspect of the present disclosure, the image sensor may include a time output unit that outputs a time when the event generation unit generated the event.

According to the above configuration, it is possible to recognize the time when the event occurred.

In the distance measuring device according to one aspect of the present disclosure, the image sensor includes a received light amount output unit that outputs information indicating the amount of light received by the light receiving element when the event generation unit generates the event. good too.

According to the above configuration, it is possible to recognize the brightness when an event occurs.

A distance measuring device according to an aspect of the present disclosure includes at least one of a plurality of the light emitting elements, and a light splitter that splits light emitted from the light emitting elements into a plurality of the irradiation beams. may

According to the above configuration, since a plurality of irradiation beams can be generated, the measurement area of the distance measuring device can be expanded.

In the distance measuring device according to one aspect of the present disclosure, the light emitting direction of the light emitting element may be formed such that the reflection trajectories of the plurality of irradiation beams do not overlap.

According to the above configuration, it is possible to eliminate confusion of a plurality of reflected beams on the image sensor due to overlap of reflection trajectories, thereby improving measurement accuracy.

In the distance measuring device according to an aspect of the present disclosure, the light emitting directions of the one or more light emitting elements may be formed such that the reflection trajectories of the plurality of irradiation beams irradiated at the same time do not overlap.

According to the above configuration, it is possible to eliminate confusion of a plurality of reflected beams on the image sensor due to overlap of reflection trajectories, thereby improving measurement accuracy.

An automatic door system according to an aspect of the present disclosure includes: a distance measuring device; a detecting device that detects a passerby using the distance measured by the distance measuring device; and an automatic door that is

An opening/closing system according to an aspect of the present disclosure includes the distance measuring device, a detecting device that detects a passerby and a passing object using the distance measured by the distance measuring device, and based on the detection result of the detecting device. at least one of a shutter and a gate that are opened and closed by

In order to solve the above-described problems, a distance measurement method according to an aspect of the present disclosure is a distance measurement device including a light emitting element and an image sensor in which a plurality of pixels including a light receiving element are two-dimensionally arranged, A distance measurement method for measuring a distance to a measurement object, wherein when the amount of light received by each of the plurality of light receiving elements exceeds a first threshold, the position of the pixel provided with the light receiving element on the image sensor is output. A position output step and a point where the reflected beam from the light emitting element reflected by the object forms an image on the image sensor are connected on the image sensor while changing the distance from the object. A position determination step of determining whether or not the position is on the reflection locus when a line is the reflection locus, and a distance between the position and the object when the position is on the reflection locus. and a distance derivation step of using the relationship to derive a distance to the object.

According to the above configuration, the distance derivation process is performed only for the light receiving elements whose received light amount exceeds the first threshold. Therefore, the amount of processing for distance derivation can be reduced.

Furthermore, the distance derivation process is performed only when the position of the light receiving element among the light receiving elements whose light receiving amount exceeds the first threshold is on the reflection locus. Therefore, since it is not necessary to scan the entire image sensor, the amount of processing for distance derivation can be further reduced.

According to one aspect of the present disclosure, the amount of processing for distance measurement can be reduced.

1 is a block diagram showing the main configuration of an automatic door system according to Embodiment 1 of the present disclosure; FIG. 2 is an external view of the automatic door system; FIG. 4 is a front view of an image sensor included in the automatic door system; FIG. FIG. 4 is a diagram for explaining an example of event generation by an event generation unit included in the image sensor; FIG. 4 is a diagram for explaining a reflection trajectory according to Embodiment 1 of the present disclosure; FIG. 4 is a flowchart showing an example of processing of a distance measurement method for measuring a distance to a measurement object according to Embodiment 1 of the present disclosure; 7 is a flowchart showing another example of processing of the distance measurement method for measuring the distance to the object to be measured according to the first embodiment of the present disclosure; FIG. 10 is a block diagram showing the main configuration of a shutter opening/closing system according to Embodiment 2 of the present disclosure; 4A and 4B are diagrams showing an example of a light emission pattern of an irradiation beam with which a detection region D is irradiated; FIG. FIG. 10 is a diagram showing a light emission pattern when reflection trajectories overlap when the detection device and the detection area are viewed from above the automatic door system; FIG. 11 is a diagram showing a reflection locus of each irradiation beam in the light emission pattern shown in FIG. 10; FIG. 4 is a diagram showing a light emission pattern when the reflection trajectories do not overlap when the detection device and the detection area are viewed from above the automatic door system; FIG. 13 is a diagram showing a reflection locus of each irradiation beam in the light emission pattern shown in FIG. 12;

[Embodiment 1]
An embodiment of the present disclosure will be described in detail below. FIG. 1 is a block diagram showing the main configuration of an automatic door system 1 according to this embodiment. FIG. 2 is an external view of the automatic door system 1. FIG. FIG. 2 is a view of the automatic door 10 viewed from the outside, and shows a state in which a first sliding door 11 and a second sliding door 12, which will be described later, are in a closed state.

Note that although an example in which the detection device 30 is provided in the automatic door system 1 will be described below, the application of the detection device 30 is not limited to this. The distance measurement function of the detection device 30 can be used in systems other than the automatic door system 1 that require distance measurement.

As shown in FIGS. 1 and 2, the automatic door system 1 includes an automatic door 10, a detector 30, and a door opening/closing controller 40. As shown in FIG.

The automatic door 10 has a first sliding door 11 and a second sliding door 12 . The opening/closing operations of the first sliding door 11 and the second sliding door 12 are controlled by a door opening/closing control section 40, which will be described later.

The detection device 30 includes one or more light emitting elements 31 , a light splitter 32 , an image sensor 33 and a controller 34 .

The light emitting element 31 is an element that irradiates a detection area of the detection device 30 with light as an irradiation beam. The light emitting element 31 emits pulsed light for a predetermined time.

The light splitter 32 splits the light emitted from the light emitting element 31 into a plurality of lights (irradiation beams). The light emitted from the light emitting element 31 is split by the light splitter 32 to form a light emission pattern of the irradiation beam emitted from the detection device 30 . Details of the light emission pattern will be described later. Since the light emitted from the light emitting element 31 can be split by the light splitter 32 into a plurality of irradiation beams, a plurality of irradiation beams can be generated from one light emitting element 31 . Thereby, the detection area of the detection device 30 can be expanded.

The image sensor 33 is a sensor that forms an image of a reflected beam, which is an irradiation beam emitted from the light emitting element 31 and reflected by an object. FIG. 3 is a front view of the image sensor 33. FIG. As shown in FIG. 3, the image sensor 33 has a plurality of pixel portions 33A arranged two-dimensionally, and each pixel portion 33A includes a light receiving element 33Aa. Thus, the image sensor 33 has a plurality of light receiving elements 33Aa arranged two-dimensionally. The plurality of light receiving elements 33</b>Aa receive reflected beams of the irradiation beams emitted from the light emitting elements 31 that are reflected by the object, and the reflected beams form an image on the image sensor 33 . The plurality of light-receiving elements 33Aa are optically separated from each other, and their temporal operations are separated.

As shown in FIG. 1, each of the plurality of pixel units 33A is provided with a threshold determination unit 33Ab and an event generation unit 33Ac. For simplification, only two pixel portions 33A are shown in FIG.

The threshold determination unit 33Ab determines whether or not the amount of light received by each light receiving element 33Aa exceeds a predetermined threshold (hereinafter referred to as a first threshold). Further, the threshold determination section 33Ab determines whether or not the amount of light received by each light receiving element 33Aa is below a predetermined threshold (hereinafter referred to as a second threshold).

The event generation unit 33Ac determines that the threshold determination unit 33Ab determines that the amount of light received by each light receiving element 33Aa exceeds the first threshold, or that the threshold determination unit 33Ab determines that the amount of light received by each light receiving element 33Aa is below the second threshold. Generates an event when it is determined. Hereinafter, an event that occurs when the amount of light received by the light receiving element 33Aa exceeds the first threshold is referred to as a positive event, and an event that occurs when the amount of light received by the light receiving element 33Aa falls below the second threshold is referred to as a negative event. Sometimes.

FIG. 4 is a diagram for explaining an example of event generation by the event generation unit 33Ac. As shown in FIG. 4, as an example, it is assumed that a reflected beam is not imaged from time t0 to time t1 in a certain light receiving element 33Aa, and a reflected beam is imaged from time t1 to time t2. Between time t0 and time t1, the certain light receiving element 33Aa does not form an image of the reflected beam, but receives external light (for example, sunlight). Then, the amount of light received is RA) is imaged.

In such a case, the threshold determination section 33Ab sets the first threshold (hereinafter referred to as first threshold P1) from time t0 to time t1 as a ratio to the amount of received light RA. That is, the threshold determination unit 33Ab determines the received light amount RA by adding a first percentage (for example, 20%) of the received light amount RA to the received light amount RA so as to be larger than the reference received light amount. It is set as the first threshold value P1.

The threshold determination unit 33Ab also sets the second threshold (hereinafter referred to as the second threshold P2) from time t0 to time t1 as a ratio to the amount of received light RA. That is, the threshold determination unit 33Ab determines the amount of received light by subtracting a second percentage (for example, 10%) of the amount of received light RA from the amount of received light RA so that the amount of received light RA is smaller than the reference amount of received light. It is set as the second threshold value P2.

The threshold determination unit 33Ab sets the absolute value of the first ratio for setting the first threshold to be larger than the absolute value of the second ratio for setting the second threshold. In the above examples of the first threshold P1 and the second threshold P2, the absolute value of the first ratio is 20 and the absolute value of the second ratio is 10, so the above setting conditions are satisfied.

The event generation unit 33Ac is configured when the threshold determination unit 33Ab determines that the amount of light received by the certain light receiving element 33Aa has become the amount of light received RB larger than the first threshold P1 due to the formation of an image of the reflected beam, that is, at time At t1, a positive event is generated.

The threshold determination unit 33Ab updates the first threshold and the second threshold when an event occurs. In the example illustrated in FIG. 4, the threshold determination unit 33Ab updates the first threshold and the second threshold at time t1 when the positive event occurs. The threshold determination unit 33Ab sets the first threshold after time t1 (hereinafter referred to as the first threshold P3) as a ratio to the amount of received light RB, which is the amount of received light after the positive event. That is, the threshold determination unit 33Ab sets the amount of received light RB as a reference amount of received light, and sets the amount of received light obtained by adding the first ratio of the amount of received light RB to the amount of received light RB so as to be larger than the reference amount of received light as a first threshold value P3. set.

The threshold determination unit 33Ab also sets a second threshold after time t1 (hereinafter referred to as a second threshold P4) as a ratio to the amount of received light RB. That is, the threshold determination unit 33Ab subtracts the second ratio of the received light amount RB from the received light amount RB so that the received light amount RB, which is the received light amount after the positive event, becomes smaller than the reference received light amount. The amount of received light is set as the second threshold value P4.

The event generation unit 33Ac is set when the threshold determination unit 33Ab determines that the amount of light received by the certain light receiving element 33Aa becomes RA smaller than the second threshold P4, that is, at time t2. , to generate a negative event.

Here, as described above, the first threshold and the second threshold are such that the absolute value of the first percentage for setting the first threshold is greater than the absolute value of the second percentage for setting the second threshold. is set to be Therefore, the reflected beam is no longer imaged, and the amount of received light RA at time t2 when the amount of received light at the certain light receiving element 33Aa changes from time t0 to the amount of received light RA at time t1 falls below the second threshold value P4, and the event generating section 33Ac can generate negative events.

The event generation unit 33Ac determines whether the event is an event (ie, a positive event) that occurs when the amount of received light exceeds the first threshold, or an event (ie, a negative event) occurs when the amount of received light falls below the second threshold. An event is generated so that it is possible to identify whether

The image sensor 33 further includes a position output section 33B, an event time output section 33C (time output section), and a received light amount output section 33D.

The position output unit 33B outputs the position in the image sensor 33 of the pixel unit 33A having the light receiving element 33Aa when the amount of light received by each of the plurality of light receiving elements 33Aa exceeds the first threshold. Specifically, the position output unit 33B outputs to the control unit 34 the position in the image sensor 33 of the pixel unit 33A for which the event generation unit 33Ac has generated an event. The position output unit 33B outputs two-dimensional coordinates as the position on the image sensor 33. FIG.

The event time output unit 33C outputs to the control unit 34 the time when the event generation unit 33Ac generated the event. The control unit 34 can recognize the time when the event occurred from the output from the event time output unit 33C.

When the event generating section 33Ac generates an event, the received light amount output section 33D outputs to the control section 34 information indicating the received light amount of the light receiving element 33Aa of the pixel section 33A that generated the event. The brightness when the event occurs can be recognized from the output from the received light amount output section 33D.

The control unit 34 controls each unit of the detection device 30 . The control unit 34 includes a same-pixel event determination unit 34A, a position determination unit 34B, a distance derivation unit 34C, and a detection unit 34D.

When the event generation unit 33Ac generates a plurality of events, the same pixel event determination unit 34A determines whether or not a negative event has occurred after a positive event has occurred in the same light receiving element 33Aa within a predetermined period of time. judge. In other words, the same-pixel event determination unit 34A determines whether the amount of light received by the same light-receiving element 33Aa exceeds the first threshold and then falls below the second threshold within a predetermined period of time. The predetermined time may be, for example, the pulse irradiation time of the irradiation beam emitted by the light emitting element 31 . As a result, the reflected beam is imaged at the pixel portion 33A determined by the same pixel event determination portion 34A that a negative event has occurred after a positive event has occurred in the same pixel portion 33A during the pulse irradiation time. It can be identified as the pixel portion 33A.

After the occurrence of the positive event, the same-pixel event determination section 34A outputs the position information of the pixel section 33A determined that the negative event has occurred to the position determination section 34B.

The position determination unit 34B determines whether or not the position of the pixel unit 33A for which the event generation unit 33Ac generated the event output by the position output unit 33B is on the reflection trajectory described later.

FIG. 5 is a diagram for explaining the reflection trajectory. As shown in FIG. 5, for each of the irradiation beams emitted from the light emitting element 31 and split by the light splitter 32, the image sensor 33 captures an image of the reflected beams of the irradiation beams reflected by the object. A line connecting the points formed on the sensor 33 with different distances from the object on the image sensor 33 is stored as a locus of reflection. FIG. 5 shows the reflection trajectory A1 and the reflection trajectory A2 regarding two irradiation beams out of a plurality of irradiation beams.

Here, when the irradiation areas of the plurality of irradiation beams simultaneously emitted from the light emitting element 31 are close to each other, the reflection trajectories of the plurality of irradiation beams may overlap. Since it is not possible to determine whether or not it is, the distance cannot be calculated accurately.

Therefore, in one aspect of the present disclosure, by adjusting the light emitted from the light emitting elements 31, the light emission directions of the one or more light emitting elements 31 are adjusted so that the reflection trajectories of the plurality of irradiation beams emitted at the same time do not overlap. is preferably formed. For example, when it is desired to simultaneously irradiate a plurality of irradiation beams to irradiation regions close to each other in a first direction (e.g., horizontal direction), regions separated from each other by a predetermined distance or more in a direction different from the first direction (e.g., vertical direction) By irradiating a plurality of irradiation beams onto the surface, it is possible to prevent the reflection trajectories of the plurality of irradiation beams from overlapping each other. As a result, it is possible to specify on which trajectory of the irradiation beam the pixel portion 33A in which the event has occurred is located, so that it is possible to improve the measurement accuracy. Note that when a plurality of irradiation beams are irradiated at different timings, the reflection trajectories of the plurality of irradiation beams may overlap.

In one aspect of the present disclosure, by adjusting the light emitted from the light emitting elements 31, the light emitting directions of the one or more light emitting elements 31 are formed such that the reflection trajectories of any irradiation beams do not overlap each other. may That is, the light emitted from the light-emitting element 31 may be adjusted so that all the reflection trajectories of the plurality of irradiation beams do not overlap. As a result, even if a plurality of beams are irradiated at the same time, the reflection trajectories of the plurality of irradiation beams can be prevented from overlapping each other, so that the measurement accuracy can be improved.

As described above, the position determination unit 34B determines whether the position of the pixel unit 33A in which the event generation unit 33Ac has generated an event is on any of the plurality of reflection trajectories. If the position of the pixel section 33A is on any of the plurality of reflection trajectories, the position determination section 34B outputs the position to the distance derivation section 34C.

In one aspect of the present disclosure, the position determination unit 34B determines that, after a positive event has occurred, only for the pixel units 33A determined by the same pixel event determination unit 34A that a negative event has occurred, the pixel units 33A have a plurality of reflection trajectories. It may be determined whether or not it is on one of the reflection trajectories. Here, the light receiving element 33Aa whose amount of light received by the irradiation beam exceeds the first threshold value should fall below the second threshold value after the irradiation of the irradiation beam ends. According to the above configuration, it is possible to determine whether or not the light receiving element 33Aa whose light receiving amount exceeds the first threshold is the same as the light receiving element 33Aa whose light receiving amount is less than the second threshold. Therefore, it can be confirmed by the irradiation beam that the amount of light received by the light receiving element 33Aa exceeds the first threshold value, and the position of the pixel portion 33A where the event has occurred can be accurately recognized by the irradiation beam. In addition, since processing is performed only when an event occurs due to stopping irradiation of the irradiation beam, the amount of processing can be reduced.

The distance derivation unit 34C derives the distance to the measurement object using the position of the pixel unit 33A on one of the reflection trajectories output by the position determination unit 34B. As described above, the reflection trajectory is a line connecting the points where the reflected beam forms an image on the image sensor 33 while varying the distance from the object. The distance derivation unit 34C stores in advance the distance between the image sensor 33 and the object for each of the pixel units 33A on the reflection trajectory in association with the position of the pixel unit 33A. Note that, instead of the distance between the image sensor 33 and the object, the distance between the automatic door system 1 provided with the detection device 30 including the image sensor 33 and the object is stored in advance in association with the position of the pixel portion 33A. may be

Upon receiving the position of the pixel unit 33A from the position determination unit 34B, the distance derivation unit 34C reads out the distance between the image sensor 33 and the object corresponding to the position, thereby obtaining the distance from the image sensor 33 to the object to be measured. to derive That is, when the position of the pixel portion 33A on any of the reflection loci output by the position determination portion 34B is on the reflection locus, the distance deriving portion 34C calculates the distance between the position of the pixel portion 33A and the object. is used to derive the distance from the image sensor 33 to the object. The distance derivation unit 34C outputs the derived distance from the image sensor 33 to the measurement object to the detection unit 34D.

The detection unit 34D detects a passerby using the distance from the image sensor 33 to the measurement target output from the distance derivation unit 34C. In other words, the detection unit 34D uses the distance from the image sensor 33 to the measurement target output from the distance derivation unit 34C to determine whether or not the passerby has been detected. For example, the detection unit 34D may detect a passerby when the distance from the image sensor 33 to the object to be measured is shorter than a predetermined distance. The detection unit 34D outputs the passerby detection result to the door opening/closing control unit 40. FIG.

The door opening/closing control unit 40 controls the opening/closing operation of the automatic door 10 based on the detection result of the passerby present near the automatic door 10 detected by the detection unit 34D. For example, the door opening/closing control unit 40 may open the automatic door 10 when receiving a detection result indicating that a passerby is present near the automatic door 10 from the detection unit 34D.

As described above, in the automatic door system 1 according to the present embodiment, the light emitting element 31, the light splitter 32, the image sensor 33, the same-pixel event determination section 34A, the position determination section 34B, and the distance derivation section 34C function as a distance measuring device. do. The automatic door system 1 also includes a detector 34D that detects a passerby using the distance measured by the distance measuring device. That is, the detection device 30 has functions as a distance measurement device that measures the distance from the image sensor 33 to the object to be measured, and as a detection device that detects a passerby. The automatic door system 1 also includes a door opening/closing control section 40 that controls the opening/closing operation of the automatic door 10 based on the detection result of the passerby detected by the detection section 34D. In other words, in the automatic door system 1, the automatic door 10 is opened and closed based on the detection result of the passerby determined using the distance measured by the distance measuring device.

Next, a distance measurement method for measuring the distance to the measurement object by the detection device 30 will be described. A distance measurement method using only positive events and a distance measurement method using both positive and negative events will be described below.

FIG. 6 is a flow chart showing an example of processing of a distance measurement method using only positive events. As shown in FIG. 6, in the distance measurement method using only positive events, first, light is emitted from the light emitting element 31 according to an instruction from the control unit 34 (step S1, irradiation step). The light emitted from the light emitting element 31 is split into a plurality of irradiation beams by the light splitter 32, and the detection area D is irradiated with a predetermined light emission pattern.

Next, in each pixel section 33A, the threshold determination section 33Ab determines whether or not the amount of light received by the light receiving element 33Aa exceeds the first threshold (step S2). If the amount of received light does not exceed the first threshold (No in step S2), the process returns to step S1.

On the other hand, when the amount of received light exceeds the first threshold (YES in step S2), the event generation section 33Ac generates a positive event in the pixel section 33A including the light receiving element 33Aa (step S3, event generation step). When the event generation section 33Ac generates a positive event, the position output section 33B outputs the position of the pixel section 33A where the positive event has occurred to the position determination section 34B.

Next, the position determination unit 34B determines whether the position of the pixel unit 33A output by the position output unit 33B, that is, the position of the pixel unit 33A for which the event generation unit 33Ac has generated a positive event, is determined from any of the plurality of reflection trajectories. It is determined whether or not it is on the reflection trajectory (step S4, position determination step).

If the position of the pixel section 33A where the event generating section 33Ac generated the event is not on any of the plurality of reflection trajectories (NO in step S4), the process returns to step S1.

On the other hand, if the position of the pixel unit 33A where the event generation unit 33Ac has generated the event is on one of the plurality of reflection trajectories (YES in step S4), the distance derivation unit 34C determines the position determination unit The distance to the measurement target is derived using the position of the pixel section 33A on one of the reflection trajectories output by 34B (step S5, distance derivation step).

As described above, in the detection device 30 according to the present embodiment, the distance derivation process is performed only for the pixel section 33A for which the event generation section 33Ac has generated an event. Therefore, the amount of processing for distance derivation can be reduced compared to the conventional technology that performs distance derivation processing for all pixels.

Further, the detection device 30 determines whether or not the position of the pixel section 33A where the event occurs is on the reflection locus, and performs distance derivation processing only when the position of the pixel section 33A is on the reflection locus. . Therefore, since it is not necessary to scan the entire image sensor 33, the amount of processing for distance derivation can be further reduced.

Further, in the detection device 30, the distance derivation unit 34C reads out the previously stored distance between the image sensor 33 and the object corresponding to the position of the pixel unit 33A. Derive the distance of Thereby, the amount of processing for distance derivation can be further reduced.

FIG. 7 is a flow chart showing an example of processing of a distance measurement method using both positive events and negative events. As shown in FIG. 7, in the distance measurement method using both the positive event and the negative event, first, light is emitted from the light emitting element 31 according to an instruction from the control section 34 (step S11, irradiation step). The light emitted from the light emitting element 31 is split into a plurality of irradiation beams by the light splitter 32, and the detection area D is irradiated with a predetermined light emission pattern.

Next, in each pixel section 33A, the threshold determination section 33Ab determines whether or not the amount of light received by the light receiving element 33Aa exceeds the first threshold (step S12). If the received light amount does not exceed the first threshold (No in step S12), the process returns to step S11.

On the other hand, when the amount of received light exceeds the first threshold (YES in step S12), the event generation unit 33Ac generates a positive event in the pixel unit 33A including the light receiving element 33Aa (step S13, event generation step). When the event generating section 33Ac generates a positive event, the position output section 33B outputs to the control section 34 the position of the pixel section 33A where the positive event has occurred.

Next, the position determination unit 34B determines whether the position of the pixel unit 33A output by the position output unit 33B, that is, the position of the pixel unit 33A for which the event generation unit 33Ac has generated a positive event, is determined from any of the plurality of reflection trajectories. It is determined whether or not it is on the reflection locus (step S14, position determination step). If the position of the pixel section 33A where the event generating section 33Ac has generated the event is not on any of the plurality of reflection trajectories (NO in step S4), the process returns to step S11.

On the other hand, if the position of the pixel portion 33A where the event generating portion 33Ac has generated the event is on one of the plurality of reflection trajectories (YES in step S14), the control portion 34 causes the pixel portion 33A to The position is stored (step S15).

Next, when the light irradiation from the light emitting element ends (step S16), in each pixel section 33A, the threshold determination section 33Ab determines whether or not the amount of light received by the light receiving element 33Aa is below the second threshold (step S17). . If the amount of received light is not below the second threshold (No in step S17), the process returns to step S11.

On the other hand, when the amount of received light is less than the second threshold (YES in step S17), the event generation section 33Ac generates a negative event in the pixel section 33A including the light receiving element 33Aa (step S18, event generation step). When the event generation section 33Ac generates a negative event, the position output section 33B outputs the position of the pixel section 33A where the negative event occurred to the control section .

Next, the same-pixel event determination unit 34A determines whether the position of the pixel unit 33A in which the negative event occurred output from the position output unit 33B is the same as the position of the pixel unit 33A in which the positive event occurred stored in step S15. is determined (step S19). If the position of the pixel section 33A in which the negative event occurred output from the position output section 33B is different from the position of the pixel section 33A in which the positive event occurred stored in step S15 (No in step S19), the process returns to step S11.

On the other hand, if the position of the pixel portion 33A in which the negative event occurred output from the position output portion 33B is the same as the position of the pixel portion 33A in which the positive event occurred stored in step S15 (Yes in step S19), the distance is derived. The unit 34C derives the distance to the measurement target using the position of the pixel unit 33A on one of the reflection trajectories output by the position determination unit 34B (step S20, distance derivation step).

In the distance calculation method using both the positive event and the negative event described above, it is determined whether or not the amount of received light in the same pixel portion 33A exceeds the first threshold value and then falls below the second threshold value in the same pixel portion 33A. be able to. Therefore, it can be confirmed by the irradiation beam that the amount of light received in the pixel portion 33A exceeds the first threshold value, and the position of the pixel portion 33A where the event has occurred by the irradiation beam can be accurately recognized. In addition, since processing is performed only when a negative event occurs due to stopping irradiation of the irradiation beam, the amount of processing can be reduced.

[Embodiment 2]
Other embodiments of the present disclosure are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

In the first embodiment, a mode of applying the detection device 30 to an automatic door system has been described, but in this embodiment, a mode of applying the detection device 30 to a shutter opening/closing system (opening/closing system) will be described.

FIG. 8 is a block diagram showing the main configuration of the shutter opening/closing system 2 in this embodiment. As shown in FIG. 8, the shutter opening/closing system 2 includes a shutter 50 and a shutter opening/closing control section 60 instead of the automatic door 10 and the door opening/closing control section 40 in the first embodiment.

The shutter opening/closing control unit 60 controls the opening/closing operation of the shutter 50 based on the detection result of the passerby present in the vicinity of the shutter 50 detected by the detection unit 34D. For example, the shutter opening/closing control unit 60 may open the shutter 50 when receiving a detection result indicating that a passerby or a passing object exists near the shutter 50 from the detection unit 34D.

Also in the shutter opening/closing system 2 of the present embodiment, the opening/closing operation of the shutter 50 is controlled based on the detection result of the detection device 30, like the automatic door system 1 of the first embodiment. Therefore, the distance from a passerby or a passing object to the shutter 50 can be measured with a small amount of processing as compared with a conventional shutter opening/closing system.

In the first and second embodiments described above, the detection device 30 is applied to an automatic door system or a shutter opening/closing system. It can also be applied to a door opening and closing system.

[Configuration example in which reflection trajectories do not overlap]
Next, a configuration example in which reflection loci do not overlap will be described with reference to FIGS. 9 to 13. FIG. First, the irradiation beam emitted from the detection device 30 will be described with reference to FIG. FIG. 9 is a diagram showing an example of a light emission pattern of an irradiation beam that irradiates the detection area D. As shown in FIG. As described above, the light emitted from the light emitting element 31 of the detection device 30 is split by the light splitter 32 . The split light becomes a plurality of irradiation beams as shown in FIG. 9, and the detection area D is irradiated. Each dot B shown in FIG. 9 indicates the irradiation position of each irradiation beam in the detection region D. FIG. Therefore, each dot B can be said to be the position of the irradiation beam in the detection area D. FIG. In the example shown in FIG. 9, the dots B are arranged in a direction parallel to the automatic door 10 at predetermined intervals in the detection region D, and are arranged in parallel with the automatic door 10 at predetermined intervals. Dots B that appear are also arranged in a direction away from the automatic door 10.例文帳に追加Note that this is an example of the emission pattern of the irradiation beam.

Next, with reference to FIGS. 10 and 11, an example in which reflection loci overlap will be described. FIG. 10 is a diagram showing a light emission pattern when the detection device 30 and the detection area D are viewed from above the automatic door system 1. As shown in FIG. As shown in FIG. 10, a straight line connecting the dots B in the detection area D in the direction of the automatic door 10 is defined as a first straight line L1, and a straight line connecting the light emitting element 31 and the image sensor 33 is defined as a second straight line L2. In other words, the dots B indicating the positions of the irradiation beams are arranged on the first straight line L1. Also, the light emitting element 31 and the image sensor 33 are arranged on the second straight line L2. In the example shown in FIG. 10, there are six first straight lines L1 from a first straight line L1A to a first straight line L1G. Here, the first straight line L1A to the first straight line L1G are collectively referred to as the first straight line L1.

FIG. 11 shows the reflection trajectory of each irradiation beam in the light emission pattern shown in FIG. FIG. 11 shows, as an example, reflection trajectories when the distance to the object is moved from 0.5 m to 4 m. FIG. 11 shows the reflection trajectory R corresponding to each dot B shown in FIG.

Reference numeral 1101 in FIG. 11 denotes the locus of reflection R when the distance to the object is moved from 2 m to 4 m. 1102 is the locus of reflection R when the distance to the object is moved from 1.5 m to 4 m. 1103 is the locus of reflection R when the distance to the object is moved from 0.5 m to 4 m.

As indicated by 1101 in FIG. 11, if the distance to the object is between 2m and 4m, the reflection trajectories R do not overlap each other. Therefore, in this case, the distance to the object can be accurately derived. Also, as indicated by 1102 in FIG. 11, the reflection trajectories R do not overlap even when the distance to the object is between 1.5 m and 4 m. Therefore, also in this case, the distance to the object can be derived. However, as indicated by 1103 in FIG. 11, when the distance to the object is changed from 0.5 m to 4 m, the respective reflection trajectories R overlap. Therefore, in this case, the distance to the object cannot be derived accurately.

For example, the direction in which the line segment of the reflection locus R1 (FIG. 11) corresponding to the irradiation beam of the dot B1 (FIG. 10) extends and the line segment of the reflection locus R2 (FIG. 11) corresponding to the irradiation beam of the dot B2 (FIG. 10) Therefore, in the example indicated by 1103 in FIG. 11, the reflection trajectory R1 and the reflection trajectory R2 become indistinguishable.

Therefore, as shown in FIG. 10, when the first straight line L1 indicating the light emission pattern of the irradiation beam and the second straight line L2 indicating the positional relationship between the light emitting element 31 and the image sensor 33 are parallel to each other, the reflection It can be seen that the trajectories R overlap and the distance to the object cannot be derived accurately. Even if the movement distance is the same, the reflection trajectory becomes shorter as the distance to the object becomes longer, and becomes longer as the distance becomes shorter. As the case increases, the possibility that the reflection trajectories R overlap increases.

In order to solve the above-described problems, the inventors of the present application devised the positional relationship between the light emitting element 31 and the image sensor 33 and the positional relationship of the light emission pattern of the irradiation beam so that the reflection trajectories do not overlap. I found that I could do it. The configuration discovered by the inventors of the present application will be described below.

12 and 13, the positional relationship between the light emitting element 31 and the image sensor 33 and the positional relationship of the light emission pattern of the irradiation beams found by the inventors of the present application will be described. FIG. 12 is a diagram showing a light emission pattern when the detection device 30 and the detection area D are viewed from above the automatic door system 1. As shown in FIG. As shown in FIG. 12, in this configuration example, a first straight line L1 connecting the dots B in the detection area D in the direction of the automatic door 10 and a second straight line L2 connecting the light emitting element 31 and the image sensor 33 are not parallel. but has an angle α. FIG. 13 shows the reflection trajectory in this configuration example.

As in FIG. 11 described above, FIG. 13 shows, as an example, the reflection trajectory R when the distance to the object is moved between 0.5 m and 4 m. 1301 in FIG. 13 is the locus of reflection R when the distance to the object is moved from 2 m to 4 m. 1302 is the locus of reflection R when the distance to the object is moved from 1.5 m to 4 m. 1303 is the locus of reflection R when the distance to the object is moved from 0.5 m to 4 m.

In 1301, 1302, and 1303 of FIG. 13, unlike the example of FIG. 11 described above, the reflection trajectories R do not overlap at any distance from 0.5 m to 4 m to the object.

For example, the direction in which the line segment of the reflection locus R3 (FIG. 13) corresponding to the irradiation beam of the dot B3 (FIG. 12) extends and the line segment of the reflection locus R4 (FIG. 13) corresponding to the irradiation beam of the dot B4 (FIG. 12) It is the same as the direction of extension of the minute, but does not overlap. In the example indicated by 1303 in FIG. 13 as well, it is possible to distinguish between the reflection trajectory R3 and the reflection trajectory R4.

Therefore, in the case of this configuration example in which the first straight line L1 indicating the light emission pattern of the irradiation beam and the second straight line L2 indicating the positional relationship between the light emitting element 31 and the image sensor 33 are not parallel to each other, the reflection trajectory R overlaps. It can be seen that the distance to the object can be derived accurately.

Also, the angle α described above is desirably less than 90 degrees, and may be less than 45 degrees. Since the second straight line L2 is a straight line connecting the light emitting element 31 and the image sensor 33, the fact that the angle α is 90 degrees means that the light emitting element 31 and the image sensor 33 are perpendicular to the first straight line L1. They are lined up in the same direction. This leads to enlargement of the detection device 30 including the light emitting element 31 and the image sensor 33 . Therefore, by setting the angle α to be smaller than 90 degrees, or even smaller than 45 degrees, it is possible to accurately derive the distance to the object while preventing the detection device 30 from becoming large.

As described above, in the configuration discovered by the inventors of the present application, the straight line connecting the dots B, which are the positions of the irradiation beam in the detection area D, that is, the straight line connecting the positions of the irradiation beam is defined as the first straight line L1, and the light emitting element 31 and the image When a straight line connecting the sensors 33 is a second straight line L2, the directions of the first straight line L1 and the second straight line L2 are different, that is, the first straight line L1 and the second straight line L2 are not parallel.

In other words, the divided irradiation beams are arranged on a plurality of parallel first straight lines L1, and the direction of the first straight lines L1 and the second straight line L2 connecting the light emitting element 31 and the image sensor 33 are aligned. It is a configuration different from the direction of

With this configuration, it is possible to prevent reflection trajectories from overlapping regardless of whether the measurement distance is short or long. Therefore, the detection device 30 can accurately derive the distance to the object regardless of whether the distance to the object is short or long.

〔summary〕
A distance measuring device according to aspect 1 of the present invention includes one or more light emitting elements, and an image sensor in which a plurality of pixel units each including a light receiving element are arranged two-dimensionally, and the image sensor includes a position output unit configured to output a position of the pixel unit including the light receiving element in the image sensor when the amount of received light exceeds a first threshold, wherein the irradiation beam from the light emitting element is reflected by the object; Whether or not the position is on the reflection locus when a line connecting points on the image sensor where the reflected beam forms an image while changing the distance from the object is defined as a reflection locus. and a distance derivation unit for deriving the distance to the object using the relationship between the position and the distance to the object when the position is on the reflection trajectory Prepare.

In the distance measuring device according to aspect 2 of the present invention, in aspect 1, each of the plurality of pixel units includes an event generation unit that generates an event when the amount of light received by each light receiving element exceeds the first threshold. and the position output section outputs the position in the image sensor of the pixel section at which the event generation section generated the event.

In the distance measuring device according to aspect 3 of the present invention, in aspect 1 or 2, the first threshold value and the second threshold value are set as a ratio to a reference amount of received light, and the reference amount of received light is set after the occurrence of the event. The amount of received light indicated by the first threshold is larger than the reference amount of received light by a first percentage of the reference amount of received light, and the amount of received light indicated by the second threshold is updated to the amount of received light after the occurrence. The amount of received light is smaller than the reference amount of received light by a second percentage, and the event generation unit detects that the amount of received light in the light receiving element exceeds the first threshold and falls below the second threshold, Generate the event.

A distance measuring device according to aspect 4 of the present invention is the distance measuring device according to any one of aspects 1 to 3, wherein the event generation unit determines whether the received light amount exceeds the first threshold value or falls below the second threshold value. generate an event that identifies the

The distance measuring device according to aspect 5 of the present invention is the distance measuring device according to any one of aspects 1 to 4, wherein the absolute value of the first ratio for setting the first threshold is the Same-pixel event determination for determining whether the amount of received light, which is larger than the absolute value of the second ratio and falls below the second threshold after exceeding the first threshold, in the same light-receiving element within a predetermined period of time. and the position determination unit selects the light receiving element for which the same-pixel event determination unit determined that the received light amount fell below the second threshold after exceeding the first threshold in the same light receiving element. It is determined whether or not the position of the provided pixel portion is on the reflection locus.

In the distance measuring device according to aspect 6 of the present invention, in any one of aspects 1 to 5, the image sensor includes a time output unit that outputs the time when the event generation unit generated the event.

A distance measuring device according to aspect 7 of the present invention is the distance measuring device according to any one of aspects 1 to 6, wherein the image sensor includes information indicating the amount of light received by the light receiving element when the event generation unit generates the event. A received light amount output unit for outputting is provided.

A distance measuring device according to aspect 8 of the present invention, in any one of aspects 1 to 7, includes a plurality of the light-emitting elements, and a light splitting device that splits the light emitted from the light-emitting elements into a plurality of the irradiation beams. at least one of:

In the distance measuring device according to aspect 9 of the present invention, in any one of aspects 1 to 8, the light emitting direction of the light emitting element is formed so that the reflection trajectories of the plurality of irradiation beams do not overlap.

A distance measuring device according to aspect 10 of the present invention is the distance measuring device according to any one of aspects 1 to 9, wherein the light emitting directions of the one or more light emitting elements are arranged such that the reflection trajectories of the plurality of irradiation beams irradiated at the same time do not overlap. is formed.

A distance measuring device according to aspect 11 of the present invention is the distance measuring device according to any one of aspects 1 to 10, wherein the plurality of irradiation beams from the plurality of light emitting elements or the plurality of irradiation beams split by the light splitter include a plurality of and the direction of the first straight line is different from the direction of the second straight line connecting the light emitting element and the image sensor.

A twelfth aspect of the present invention is the distance measuring device according to any one of the first to eleventh aspects, wherein an angle formed by the first straight line and the second straight line is smaller than 90 degrees.

A thirteenth aspect of the present invention is the distance measuring device according to any one of the first to twelfth aspects, wherein an angle formed by the first straight line and the second straight line is smaller than 45 degrees.

An automatic door system according to aspect 14 of the present invention includes the distance measuring device according to any one of aspects 1 to 13 and an automatic door, wherein the automatic door uses the distance measured by the distance measuring device The door is opened and closed based on the determined passerby detection result.

An opening/closing system according to aspect 15 of the present invention includes the distance measuring device according to any one of aspects 1 to 13, and at least one of a shutter and a gate, wherein at least one of the shutter and the gate is the distance measuring device. is opened or closed based on the results of pedestrian and pedestrian detection determined using the distances measured by .

A distance measurement method according to aspect 16 of the present invention measures a distance to a measurement target in a distance measurement device including a light emitting element and an image sensor in which a plurality of pixel units including light receiving elements are arranged two-dimensionally. A distance measuring method comprising: a position output step of outputting a position of the pixel unit including the light receiving element in the image sensor when the amount of light received by the light receiving element exceeds a first threshold; When a reflection locus is defined as a line connecting points on the image sensor where an irradiation beam reflected by an object is imaged on the image sensor while varying the distance from the object, the position is on the locus of reflection; and if the position is on the locus of reflection, the relationship between the position and the distance to the object is used to determine and a distance derivation step of deriving the distance.

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

1 automatic door system 2 shutter opening/closing system 10 automatic door 30 detector (distance measuring device)
31 light-emitting element 32 light splitter 33 image sensor 33A pixel unit 33Aa light-receiving element 33Ab threshold determination unit 33Ac event generation unit 33B position output unit 33C event time output unit (time output unit)
33D light receiving amount output unit 34 control unit 34A same pixel event determination unit 34B position determination unit 34C distance derivation unit 34D detection unit 40 door opening/closing control unit 50 shutter 60 shutter opening/closing control unit

Claims (16)

one or more light emitting elements;
an image sensor in which a plurality of pixel units including light receiving elements are arranged two-dimensionally,
The image sensor includes a position output unit that outputs the position of the pixel unit including the light receiving element in the image sensor when the amount of light received by the light receiving element exceeds a first threshold,
A reflection trajectory is defined as a line connecting points on the image sensor where the reflected beam of the irradiation beam from the light emitting element is reflected by the object and formed into an image on the image sensor while changing the distance from the object on the image sensor. a position determination unit that determines whether or not the position is on the reflection trajectory when the
a distance derivation unit that derives the distance to the object using the relationship between the position and the distance to the object when the position is on the reflection trajectory. Each of the plurality of pixel units includes an event generating unit that generates an event when the amount of light received by each light receiving element exceeds the first threshold,
2. The distance measuring device according to claim 1, wherein said position output section outputs the position in said image sensor of said pixel section at which said event generating section generated said event. The first threshold and the second threshold are set as a ratio to a reference amount of received light, and the reference amount of received light is updated to the amount of received light after the occurrence of the event,
The received light amount indicated by the first threshold is larger than the reference received light amount by a first percentage of the reference received light amount, and the received light amount indicated by the second threshold is larger than the reference received light amount by a second percentage of the reference received light amount. small,
3. The distance measuring device according to claim 2, wherein the event generation unit generates the event when the amount of light received by the light receiving element exceeds the first threshold and falls below the second threshold. 4. The distance measuring device according to claim 3, wherein said event generating section generates an event capable of identifying whether said received light amount exceeds said first threshold value or falls below said second threshold value. The absolute value of the first ratio for setting the first threshold is greater than the absolute value of the second ratio for setting the second threshold,
a same-pixel event determination unit that determines whether the amount of light received by the same light-receiving element falls below the second threshold after exceeding the first threshold within a predetermined time;
The position determination unit determines that the same-pixel event determination unit determines that the amount of received light in the same light receiving element exceeds the first threshold and then falls below the second threshold. 5. The distance measuring device according to claim 4, wherein it is determined whether or not a position is on the reflection locus. 3. The distance measuring device according to claim 2, wherein said image sensor includes a time output section for outputting the time when said event generation section generated said event. 3. The distance measuring device according to claim 2, wherein said image sensor includes a received light amount output section that outputs information indicating the received light amount of said light receiving element when said event generating section generates said event. 2. The distance measuring device according to claim 1, comprising at least one of a plurality of said light emitting elements, and a light splitter for splitting light emitted from said light emitting elements into a plurality of said irradiation beams. 9. The distance measuring device according to claim 8, wherein the light emitting direction of said light emitting element is formed so that said reflection trajectories by said plurality of said irradiation beams do not overlap. 9. The distance measuring device according to claim 8, wherein the light emitting directions of said one or more light emitting elements are formed so that said reflection trajectories by said plurality of irradiation beams irradiated simultaneously do not overlap. The plurality of irradiation beams from the plurality of light emitting elements or the plurality of irradiation beams split by the light splitter are arranged on a plurality of parallel first straight lines,
9. The distance measuring device according to claim 8, wherein the direction of said first straight line is different from the direction of a second straight line connecting said light emitting element and said image sensor. 12. The distance measuring device according to claim 11, wherein an angle formed by said first straight line and said second straight line is smaller than 90 degrees. 13. The distance measuring device according to claim 12, wherein the angle formed by said first straight line and said second straight line is less than 45 degrees. A distance measuring device according to any one of claims 1 to 13;
including an automatic door;
The automatic door system, wherein the automatic door is opened and closed based on a passerby detection result determined using the distance measured by the distance measuring device. A distance measuring device according to any one of claims 1 to 13;
with at least one of a shutter and a gate;
An opening/closing system, wherein at least one of the shutter and the gate is opened/closed based on detection results of pedestrians and objects determined using the distance measured by the distance measuring device. A distance measurement method for measuring a distance to a measurement target in a distance measurement device including a light emitting element and an image sensor in which a plurality of pixel units including light receiving elements are arranged two-dimensionally, comprising:
a position output step of outputting a position of the pixel portion including the light receiving element in the image sensor when the amount of light received by the light receiving element exceeds a first threshold;
A reflection trajectory is defined as a line connecting points on the image sensor where the reflected beam of the irradiation beam from the light emitting element is reflected by the object and formed into an image on the image sensor while changing the distance from the object on the image sensor. a position determination step of determining whether or not the position is on the reflection trajectory when
and a distance deriving step of deriving a distance to the object using a relationship between the position and the distance to the object when the position is on the reflection trajectory.

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