JP2014070381A - Human body detection sensor and automatic faucet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a human body detection sensor with reduced erroneous detection and improved detection performance, and an automatic faucet.SOLUTION: A human body detection sensor 1 includes: determination means 321 which determines that there is a detection object when an incidence position belongs to a predetermined detection area among a light-receiving area of a line sensor 261; prohibition means 322 which determines that there is a non-detecting object when a pixel having a light-receiving amount within a predetermined prohibited area exists in the light-receiving area; and detection output means 325 which outputs a detection signal when the presence of a detection object is determined by the determination means 321 and if the prohibition means 322 does not determine that it is a non-detecting object, while does not output the detection signal if the prohibition means 322 determines that it is a non-detecting object.

Description

  The present invention relates to a human body detection sensor applied to an automatic faucet, an automatic cleaning device for a urinal, and the like.

  Conventionally, automatic faucets that automatically detect the user's hand-holding operation and discharge water automatically, and automatic cleaning devices for urinals that automatically detect the approaching user and supply cleaning water are known. It has been. These automatic faucets and automatic cleaning devices incorporate a human body detection sensor for detecting an approaching human body. As such a human body detection sensor, a sensor in which a light emitting element such as an LED and a light receiving element such as a PSD (Position Sensitive Detector) are offset and arranged is known.

  This human body detection sensor specifies the position where the reflected light from the detection target is incident on the PSD, and measures the distance to the detection target based on the principle of so-called triangulation. The PSD is a very simple light receiving element that outputs a signal corresponding to the position of the center of gravity of incident light, and has an advantage of low power consumption. On the other hand, information that can be acquired by PSD is only position information, and there is a fact that there are few countermeasures that can be taken when ambient light is incident. Therefore, for example, in an automatic faucet of a wash basin using a human body detection sensor including a PSD, false detection occurs due to the influence of ambient light such as specular reflected light from a wash basin, and water discharge starts even when no one is present. Such a malfunction may occur.

  For the purpose of improving detection performance, a human body detection sensor using an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) has been proposed (for example, see Patent Document 1). If it is a human body detection sensor using an image sensor, for example, there is a possibility that the detection performance can be improved by using the distribution information of the amount of received light for each pixel to eliminate the influence of ambient light. As such a human body detection sensor, a sensor has been proposed in which the specular reflection light is eliminated by using the peak intensity of the distribution waveform of the received light amount of each pixel and the waveform shape (particularly kurtosis) to reduce false detection. (For example, refer to Patent Document 2).

  However, the following problems remain even in the human body detection sensor that excludes specular reflection light by paying attention to the shape of the distribution waveform of the amount of received light. In other words, when multiple specular reflection lights are superimposed and incident, the shape of the distribution waveform of the amount of received light is different from the original specular reflection light and approaches the diffuse reflection light from the human body, so it is excluded as specular reflection light There is a risk of false detection due to failure. In particular, in the case of a human body detection sensor with a detection area set toward a concave bowl surface, such as a washbasin, specular reflection light is generated simultaneously at multiple locations on the bowl surface, and multiple specular reflection lights are superimposed (synthesized). Therefore, the possibility of incidence increases.

JP 2005-207012 A JP 2012-77472 A

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a human body detection sensor and an automatic water faucet with reduced false detection and improved detection performance.

A first aspect of the present invention includes an imaging unit including an imaging device in which pixels are arranged one-dimensionally or two-dimensionally, and a light-emitting unit arranged offset in a predetermined direction with respect to the imaging unit. A human body detection sensor for detecting a detection target located within a predetermined detection distance by the imaging unit receiving reflected light generated by the light projected by the light emitting unit,
Imaging control means for controlling an imaging operation in which light emission by the light emitting unit and light reception by the imaging unit are performed;
Reading means for reading the received light amount of the pixels constituting the image sensor;
The incident position of the reflected light in a light receiving area that is an area in which pixels constituting the image sensor are arranged in the predetermined direction is specified, and in the detection area corresponding to the predetermined detection distance in the light receiving area Determining means for determining that there is a detection target when the incident position belongs;
When the light reception amount of at least one specific pixel in the non-detection area outside the detection area in the light reception area is a non-detection target when the light reception amount exceeds a threshold set in advance for each pixel A prohibition means for judging,
Detection determination means for determining whether the detection target is detected or not detected,
When it is determined by the determination unit that there is a detection target, the detection determination unit determines that the detection is not detected by the prohibition unit. If it is determined that there is a human body detection sensor that determines non-detection regardless of the presence / absence of the determination result by the determination means and the content of the determination result (claim 1).

The second aspect of the present invention is a faucet that discharges water into a bowl provided with a drain outlet at the bottom;
A human body detection sensor according to the first aspect;
According to a detection signal of the human body detection sensor, there is an automatic water faucet provided with water supply control means for executing switching of water discharge / stop water of the water faucet or adjustment of the water discharge amount (Claim 5).

  In the human body detection sensor according to the present invention, the light receiving area that is an area in which pixels are arranged in the predetermined direction that is an offset direction between the light emitting unit and the imaging unit is set. The incident position in the light receiving area when the reflected light from the detection target is incident on the image sensor corresponds to a three-dimensional distance to the detection target based on the principle of triangulation.

  The range of the predetermined detection distance that is a three-dimensional range in which a detection target is detected is uniquely associated with the detection area that forms part of the light receiving area. For example, when there is a detection target at the far end of the predetermined detection distance, the imaging unit receives the reflected light with the maximum amount of light received by the pixel at the end of the detection area. The received light waveform representing the distribution of the received light amount when such reflected light is incident is a waveform in which the received light amount of the pixel at the end of the detection area is the maximum value, and the received light amount decreases as the distance from the pixel increases. .

  Accordingly, the distribution of the received light amount in the non-detection area in the received light waveform of the reflected light from the detection target becomes the base portion of the received light waveform having the maximum value of the received light amount in the detection area as described above. Of course, it is highly likely that the received light waveform having the maximum value in the non-detection area is not due to the reflected light to be detected. Further, in this non-detection area, if the light reception waveform is a detection target, the amount of light reception should gradually decrease as the distance from the detection area increases. For example, it is determined that a received light waveform that exhibits a large received light amount despite being away from the detection area is not likely to be reflected light of the detection target, but is likely to be reflected light other than that. it can.

  Therefore, in the human body detection sensor according to the present invention, a threshold for each pixel is set for the specific pixel belonging to the non-detection area. In this human body detection sensor, when the amount of light received by the specific pixel exceeds a corresponding threshold value, it is determined as non-detection regardless of the determination result by the determination unit. If such a light reception waveform is excluded from the detection target, erroneous detection can be avoided and detection performance can be improved.

  As described above, the human body detection sensor according to the present invention is a sensor in which false detection is reduced and detection accuracy is improved by executing threshold determination regarding the amount of received light of a specific pixel belonging to the non-detection area. The automatic faucet of the present invention provided with this human body detection sensor is a faucet with high operational reliability in which water discharge or the like due to erroneous detection is reduced.

As an image sensor applied to the human body detection sensor according to the present invention, an image sensor using a CCD or CMOS can be used.
Examples of the adjustment of the water discharge amount in the automatic faucet according to the second aspect of the present invention include adjustment of water discharge start, water discharge stop, and increase / decrease of the water discharge amount.

In the human body detection sensor according to a preferred aspect of the present invention, there is a prohibited area in which the amount of received light is less likely to be distributed when the reflected light of the detection target is received within the range in which the amount of received light of the specific pixel is distributed. The threshold value that is provided and used by the prohibition unit for threshold determination is the amount of received light that forms the lower limit boundary of the prohibition area.
The prohibited area may be a one-dimensional area corresponding to one specific pixel, or may be a two-dimensional area corresponding to a plurality of specific pixels. Furthermore, it may be a plurality of one-dimensional areas respectively provided corresponding to a plurality of specific pixels. An upper limit boundary may be set in addition to the lower limit boundary which is a boundary on the side where the amount of received light is small. In general, the amount of light received by a pixel is saturated at the physical upper limit. This upper limit may be set as the upper limit boundary of the prohibited area, and the upper limit boundary may be omitted.

In the human body detection sensor according to a preferred aspect of the present invention, the specific pixel is one or a plurality of pixels in a non-detection area farther than the detection area,
The threshold value corresponding to the specific pixel is set with reference to the received light amount of the pixel located at the far end of the detection area having a predetermined maximum value and having a normal distribution ( Claim 3).

  Since the surface of the human body that is the detection target is a diffuse reflection surface, the received light amount distribution (light reception waveform) of the reflected light in the light receiving area exhibits a normal distribution waveform corresponding to the diffuse reflected light. If the received light amount of the pixel at the far end of the detection area is the maximum value and the received light waveform in which the received light amount forming a normal distribution is set as a reference, in the non-detection area, the reference and It can be judged that there is little possibility that the amount of received light exceeding the received light waveform is caused by the reflected light from the detection target. It can be determined that there is a high possibility that the received light waveform including the received light amount exceeding the normal distribution as the reference is not due to the reflected light to be detected.

  Therefore, if the received light amount (received light amount of the specific pixel) of the reference normal distribution waveform is set as the threshold value of the specific pixel, and the received light waveform including the received light amount exceeding the threshold value is excluded, false detection is performed. Reduced with high certainty. Furthermore, the threshold value of the specific pixel may be set to a slightly higher received light amount that takes into account variations in light reception sensitivity (gain) between pixels, errors, etc., rather than the received light amount value having a normal distribution itself. good. The predetermined maximum value may be determined by simulation calculation based on the assumed reflectance of the detection target and the light emission amount of the light emitting unit, or may be experimentally determined using a test piece. The predetermined maximum value may be determined on the assumption that the intensity of the reflected light is the highest among the detection objects.

In the human body detection sensor according to a preferred aspect of the present invention, the prohibiting means normalizes the received light amount forming the actual received light amount distribution of the light receiving area using the received light amount forming the reference normal distribution, and normalizes the received light amount. A threshold judgment is executed for the received light amount (claim 4).
Even if the reflected wave has a relatively small maximum amount of received light, the absolute value of the received light amount distribution can be increased by performing the normalization as described above, and can be a target of determination processing by the prohibiting means. If it is diffuse reflection light to be detected, even if it is normalized as described above, the amount of light received in the non-detection area is less likely to exceed the threshold and is not excluded by the prohibiting means. If the normalization process as described above is performed, there is a high possibility that the reflected light, which is disturbance light, can be eliminated, and the detection accuracy of the human body detection sensor can be further improved.

The perspective sectional view showing the washstand provided with the automatic faucet in the example. Sectional drawing which shows the cross-section of a sensor unit in an Example (AA sectional view taken on the line AA in FIG. 1). The perspective view which shows the line sensor in an Example. The block diagram which shows the system configuration | structure of the human body detection sensor in an Example. The figure which illustrates the light reception waveform of the diffuse reflection light by the detection target in an Example. Explanatory drawing explaining the calculation method of the gravity center position (incident position) of a light reception waveform in an Example. Explanatory drawing of the principle of triangulation in an Example. Explanatory drawing which shows a mode that reflected light generate | occur | produces in the bowl surface in an Example. Explanatory drawing which shows a mode that reflected light AC from the bowl surface in an Example is synthesize | combined. Explanatory drawing which illustrates the erroneous detection by the synthetic | combination reflected light from a bowl surface in an Example. Explanatory drawing which shows the prohibition area in an Example. The flowchart which shows the flow of a detection process in an Example. Explanatory drawing of the example of exclusion of the disturbance light by a prohibition area in an Example. Explanatory drawing which illustrates disturbance light in an Example. Explanatory drawing of the example of exclusion of the disturbance light by a prohibition area in an Example.

The embodiment of the present invention will be specifically described with reference to the following examples.
(Example)
In this example, the human body detection sensor 1 is applied to the faucet (automatic faucet) 16 of the washstand 15. The contents will be described with reference to FIGS.
As shown in FIG. 1, the washstand 15 of this example includes a counter 155 provided with a bowl 151 that is recessed in a concave shape, and a faucet 16 having a water discharge port 168. The faucet 16 is erected on a counter top 156 that forms the upper surface of the counter 155. A drain outlet 152 for draining water is disposed at the deepest part of the pot 151.

  The faucet 16 has a substantially cylindrical body portion 160 erected on the countertop 156 and a base portion 161 that forms a pedestal of the body portion 160. The trunk portion 160 is supported by the base portion 161 while being inclined toward the bowl 151 side. A substantially cylindrical water discharge portion 162 is attached to the side surface of the body portion 160 facing the pot 151 side, and a water discharge port 168 is opened at the tip thereof. A filter plate 165 that forms a detection surface of the human body detection sensor 1 is disposed on a side surface of the body portion 160 that is an upper side of the water discharge portion 162. The filter plate 165 is a resin filter that selectively transmits light in the infrared region.

  As shown in FIGS. 1 and 2, the human body detection sensor 1 of this example includes a sensor unit 2 incorporated in a faucet 16 and a control unit 3 that controls the sensor unit 2. In the wash basin 15, an automatic water supply device is formed by a combination of the human body detection sensor 1 and a solenoid (water supply control means) 11 that is a water discharge valve (electromagnetic valve) provided in the water supply pipe 12.

  As shown in FIGS. 1 and 2, the sensor unit 2 is a unit in which the LED element 251 and the line sensor (imaging element) 261 are accommodated in the housing 21 and operates by receiving power supply from the control unit 3. In the sensor unit 2, the light emitting unit 25 and the imaging unit 26 are arranged in parallel so as to face the filter plate 165 of the faucet 16. The light emitting unit 25 that emits infrared light includes an LED element 251 and a light projecting lens 255. The imaging unit 26 includes a line sensor 261 and a condenser lens 265. The light emitting unit 25 and the imaging unit 26 are arranged offset in the horizontal direction (predetermined direction) with a partition wall 211 having a light shielding property interposed therebetween.

  As shown in FIG. 2, the LED element 251 is a light emitting element in which an LED chip 250 mounted in a cavity of a package substrate is sealed with a transparent resin 254. In the light emitting unit 25, the LED element 251 is covered with a light-shielding element case 252 provided with a slit hole 253 in the vertical direction (vertical direction). According to the light emitting unit 25, it is possible to project a sharp slit light whose horizontal divergence angle is suppressed toward a detection target.

  As shown in FIGS. 1 to 3, the line sensor 261 is a one-dimensional imaging sensor in which pixels 260 that convert a received light amount into an electrical physical amount are linearly arranged. The line sensor 261 has 64 pixels 260 as effective pixels. In the line sensor 261, a light receiving area 263 is formed by these 64 pixels 260. The line sensor 261 includes an electronic shutter (not shown), and the light reception (exposure) time of each pixel 260 can be adjusted using the electronic shutter. The line sensor 261 outputs imaging data which is one-dimensional digital data in which pixel values of 256 gradations representing the amount of received light are arranged in the arrangement order of the pixels 260 every time the light receiving operation is performed.

  In the sensor unit 2 of this example, the line sensor 261 is incorporated so that the longitudinal direction of the light receiving area 263 matches the offset direction between the light emitting unit 25 and the imaging unit 26. This sensor unit 2 is incorporated in the faucet 16 so that the bowl surface 150 which is the inner peripheral surface of the bowl 151 is expected by the light receiving area 263 of the line sensor 261. If there is no shielding object such as a hand in the imaging direction of the line sensor 261, the bowl surface 150 is included in the imaging range.

  As shown in FIGS. 1 and 4, the control unit 3 is a unit that controls the sensor unit 2 and the solenoid 11, and operates with electric power supplied from a commercial power source. The control unit 3 includes a control board 30 that controls the sensor unit 2 and the solenoid 11. The control board 30 is provided with an imaging control unit 31 that controls the line sensor 261 and the LED element 251, a detection processing unit 32 that executes detection processing, and a water supply control unit 33 that controls the solenoid 11.

The imaging control unit 31 functions as an imaging control unit 311 that controls the LED element 251 and the line sensor 261, and a reading unit 312 that reads imaging data (a received light waveform that is a distribution of received light amount of each pixel 260) from the line sensor 261. I have.
The imaging control unit 311 controls the line sensor 261 so that an intermittent operation in which an operation period and a non-operation period appear alternately is performed. The imaging control means 311 stops the power supply to the line sensor 261 until a predetermined interval time (in this example, 500 msec) has elapsed since the end of the previous operation period, and sets a non-operation period. When the interval time elapses, the power supply is resumed and the operation period is set.

  Note that the imaging control unit 311 of the present example performs exposure (light reception) of the line sensor 261 synchronized with light emission of the LED element 251 and exposure of the line sensor 261 under no light emission by an imaging operation within one operation period. Are continuously executed, and the received light amount of the difference between the two exposures is obtained for each pixel. In the received light waveform of the difference for each pixel, the influence of ambient light is suppressed and the component of reflected light due to the LED light is extracted. FIG. 5 is an example of a received light waveform obtained when diffused reflected light to be detected is incident. In the figure, the horizontal axis x indicates the pixel number (pixel position), and the vertical axis D (x) indicates the amount of received light (pixel value) of the pixel with the pixel number x.

  The detection processing unit 32 determines whether there is a detection target, a determination unit 321 that determines whether there is a detection target, a prohibition unit 322 that determines a non-detection target, a detection determination that determines whether the detection is based on the determination results of the determination unit 321 and the prohibition unit 322 Means 324 has a function as detection output means 325 for outputting a detection signal when it is determined that the detection is made.

  The determination unit 321 determines the presence or absence of a detection target using the light reception waveform (light reception amount (difference) distribution for each pixel) of FIG. 5 acquired by the imaging operation. As a first step, the determination unit 321 first performs a distance measurement process that specifies the position of the center of gravity of a received light waveform that represents the incident position of reflected light on the light receiving area 263. Thereafter, as a second step (ranging determination routine), it is determined whether or not the center of gravity position belongs to the detection area corresponding to the detection distance to be detected.

  In the first step, in order to specify the center of gravity position of the received light waveform, as shown in FIG. 6, first, the received light amount data D (x) for each pixel constituting the received light waveform is integrated, and the sum SD of the pixel values of 64 pixels is obtained. calculate. This total SD corresponds to the area of the region indicated by hatching in the lower right direction in FIG. The position of the pixel 260 (illustrated by a black circle) of the pixel number N when the integrated value obtained by integrating the pixel values of the respective pixels 260 in order from the pixel with the pixel number zero at the left end of the light receiving area 263 reaches SD / 2. The center of gravity of the received light waveform is used. Here, the integrated value SD / 2 corresponds to the area of the region indicated by the hatching with the upward slope. This region is included in the region of the total sum SD, and is grasped as a cross hatch region in FIG. The distribution of the amount of received light for each pixel in FIG. 6 schematically represents the received light waveform in FIG.

In the second step, it is determined whether or not the position of the center of gravity of the received light waveform that represents the incident position of the reflected light belongs to the detection area of FIG. This detection area is set as described below based on the principle of triangulation using the sensor unit 2.
The positional relationship between the sensor unit 2, the bowl surface 150, and the user's hand in the wash basin 15 of this example can be schematically expressed as shown in FIG. When the reflected light component of the LED light from the hand that is the detection target is incident on the line sensor 261, the incident position differs depending on the distance H to the detection target. As the distance H is shorter, the incident position of the reflected light incident on the line sensor 261 is on the upper side in the figure, and as the distance H is longer, the incident position is on the lower side. Thus, the incident position of the reflected light with respect to the line sensor 261 is proportional to the distance to the detection target, and can be an index representing the degree of this distance. The detection area (FIG. 6) set in the light receiving area 263 is an area corresponding to the detection distance (FIG. 7) to be detected. The center of gravity calculated as described above is treated as an incident position, and whether or not the center of gravity is within the detection area is determined based on whether the distance to the detection target that causes the reflected light is within the detection distance shown in FIG. It is completely synonymous with the determination of whether or not.

  Here, in the determination by the determination unit 321, an erroneous determination may occur when the reflected light from the bowl surface 150 is incident. The LED light projected toward the bowl surface 150 is slit light with a narrowed spread in the horizontal direction, but has a certain amount of spread in the vertical direction. Therefore, on the bowl surface 150 curved in a concave shape, reflection occurs simultaneously at a plurality of locations as shown in FIG. 8, and the reflected lights (A to C) are combined and incident on the sensor unit 2. Since the glaze surface 150Y forming the surface of the bowl surface 150 is close to a mirror surface and has a high reflectance, the reflected light A and B becomes specular reflection light. On the other hand, when the LED light is incident substantially perpendicular to the bowl surface 150, it passes through the glaze surface 150Y and reaches the earthenware floor 150S, and the reflected light C becomes diffusely reflected light.

  When the LED light is projected toward the bowl surface 150 in this way, as shown in FIG. 9, a plurality of specular reflection lights A and B and diffuse reflection light C and the like are simultaneously generated (superposed) to combine (superimpose) the sensor unit. Return to 2. In the case of a single specular reflection light, it can be distinguished from diffuse reflection light by determining the shape of the received light waveform (threshold judgment regarding kurtosis, etc.). On the other hand, as described above, a plurality of specular reflection lights A and B are diffused. In the reflected light combined with the reflected light C (hereinafter referred to as “combined reflected light”), as shown in the figure, the shape characteristic of the received light waveform resembles the diffuse reflected light, and the intensity of which reflected light component. There may be a deviation in the position of the center of gravity of the received light waveform depending on whether is dominant.

  As shown in FIG. 10 in which the received light waveform of the diffuse reflected light generated at the same distance as the bowl surface 150 is compared with the received light waveform of the combined reflected light in FIG. May shift within the detection area. In such a case, the determination by the determination unit 321 does not exclude the synthesized reflected light that is disturbance light, and results in a determination result that there is a detection target. The shape of the light reception waveform of the combined reflected light has a kurtosis lower than that of a single specular reflected light, and is similar to the shape of the diffusely reflected light to be detected as described above. For this reason, it is difficult to eliminate the combined reflected light by determining the shape.

The prohibiting unit 322 is a unit provided to determine that the synthetic reflected light (see FIGS. 9 and 10) by the bowl surface 150 is disturbance light and determine that it is a non-detection target.
In order to explain the determination method by the prohibiting means 322, first, the shape of the light reception waveform by the diffuse reflected light of the detection target located at the detection distance (see FIG. 7) will be described. The light reception waveform measured when a test piece (test piece in which barium sulfate is applied to the surface of the base material) that reproduces the diffuse reflection surface to be detected is set at each distance of 30 to 130 mm belonging to the detection distance, As shown in FIG.

  In the light reception waveform with a distance of 30 to 70 mm, the maximum value is unknown due to saturation of the light reception amount, while in other light reception waveforms, the light reception amount of the pixel (peak pixel) corresponding to the distance to the test piece is the maximum value. In addition, the waveform has a normal distribution. The closer the light reception waveform is, the larger the light reception amount of the peak pixel is, and the position of the peak pixel is located on the left side in the detection area. The farther the distance is, the smaller the light reception amount of the peak pixel is. Is located on the right side in the detection area.

  Then, as shown in FIG. 11, in each pixel in the non-detection area outside the detection area (far distance side), the 130 mm light reception waveform which is the far limit of the detection distance is located on the uppermost side in the figure, and the amount of received light Is the largest. In this non-detection area, the region above the 130 mm received light waveform is a region where there is a low possibility that the received light amount of the diffuse reflected light received by the detection target exists. The prohibiting unit 322 of this example actively utilizes this area and sets a prohibited area in a part of the area, thereby eliminating reflected light from the non-detection target.

  Specifically, in the non-detection area, by determining the received light amount as a threshold for each pixel based on the received light amount of the 130 mm received light waveform, the lower limit boundary (boundary on the side where the received light amount is smaller) of the prohibited area is determined. Is formed. The threshold value of each pixel is set to a value of about 110% of the amount of received light that forms a reference 130 mm received light waveform so as to absorb gain variations and errors for each pixel. As shown in FIG. 11, the threshold value that forms the lower limit boundary of the prohibited area set in this way gradually decreases as it approaches the left end of the light receiving area. Further, the left end of the prohibited area, that is, the boundary facing the detection area side, sets the position of the pixel 260 where the most preferable result was obtained experimentally. In this example, the interval between the pixel 260 forming the boundary of the prohibited area and the pixel 260 at the end of the detection area is set to about several percent of the number of pixels of the line sensor 261.

  Further, in the prohibiting unit 322 of this example, five pixels belonging to the non-detection area are set in advance as specific pixels. The prohibition unit 322 performs threshold determination between the received light amount of the specific pixel of the received light waveform to be determined and the threshold value (threshold value of the specific pixel) forming the lower limit boundary of the prohibited area. If the amount of light received by the specific pixel exceeds the threshold value, the prohibiting unit 322 determines that the light is disturbance light from the non-detection target and determines that it is a non-detection target. On the other hand, if the amount of light received by the specific pixel is less than or equal to the threshold value, it is not determined that it is a non-detection target. The determination of the combined reflected light in FIG. 9 and FIG. 10 (the light reception waveform indicated by the solid line in FIG. 10) by the prohibiting means 322 is as described later.

Next, the flow of detection processing by the human body detection sensor 1 of this example configured as described above will be described with reference to the flowchart of FIG.
After the power is turned on, first, a received light waveform acquisition routine including an imaging operation, reading of imaging data (received waveform), and the like is executed in order to acquire a received light waveform of reflected light according to the projection of the LED light (S101).

  A first prohibited area determination routine for determining whether the acquired received light waveform belongs to a prohibited area (see FIG. 11) is executed (S102). In the first prohibited area determination routine, threshold determination is performed on the absolute value of the received light amount of the specific pixel without processing the received light amount that forms the acquired received light waveform. In the first prohibited area determination routine, the received light amount of the specific pixel is acquired from the acquired received light waveform and is compared with a threshold value that forms a lower limit boundary of the prohibited area. If the received light amount of any specific pixel exceeds the threshold value, that is, the received light amount of any pixel constituting the acquired received light waveform exists in the prohibited area (S103: NO), this It can be determined that the received light waveform is due to disturbance light and is a non-detection target, and thereby non-detection determination is performed (S118).

  On the other hand, in the first prohibited area determination routine, when the received light amounts of all the specific pixels are equal to or smaller than the prohibited area threshold (S103: YES), the second prohibited area determination routine is executed (S104). This second prohibited area determination routine is different from the first prohibited area determination routine of step S102 in that normalization is performed instead of applying the received light amount of the specific pixel of the acquired light reception waveform as it is. Yes. The acquired light reception waveform is normalized by the maximum light reception amount of the 130 mm light reception waveform (solid light reception waveform in FIG. 11), and the light reception amount (relative value) of the specific pixel obtained by this normalization is the second. This is applied to the prohibited area determination routine (S104).

  When the light reception amount (relative value) of any specific pixel exceeds the threshold value of the prohibited area by this second prohibited area determination routine, that is, when a part of the received light waveform is included in the prohibited area (S105: NO), based on the determination that the received light waveform is derived from disturbance light, it can be determined that it is a non-detection target, and a non-detection determination is made (S118).

  On the other hand, if the received light amount of all the specific pixels is equal to or less than the threshold value forming the lower limit boundary of the prohibited area in step S105 (S105: YES), the distance measurement determination routine based on the principle of triangulation by the determination means 321 is performed. It is executed (S106). Here, as described above, the centroid position of the received light waveform is calculated, and whether or not the centroid position belongs to the detection area (see FIG. 6), that is, the distance to the detection target is within the detection distance range. Is determined (S107). If the position of the center of gravity belongs to the detection area (S107: YES), it can be determined that there is a detection target, and a detection determination is made (S108). On the other hand, if the position of the center of gravity does not belong to the detection area and the distance to the detection target is outside the detection distance range (S107: NO), a non-detection determination is made (S118).

  Of the series of detection processes of FIG. 12, the first prohibited area determination routine of step S102 is, for example, a bowl in which the peak pixel belongs to the detection area but part of the received light waveform is included in the prohibited area. This effectively acts on the combined reflected light (FIGS. 9 and 10) of the surface 150. As shown in FIG. 13, the received light waveform of the combined reflected light is partly included in the prohibited area, and can be easily eliminated by the determination based on the threshold value that forms the lower limit boundary of the prohibited area as described above.

  Further, the second prohibited area determination routine in step S104 effectively acts on, for example, the solid-line specular reflected light among the two types of specular reflected light having the same mirror surface in FIG. The difference between the solid-line specular reflection light and the broken-line specular reflection light lies in the vertical inclination of the specular reflection surface. The broken-line specular reflection light is caused by the specular reflection surface that has almost no vertical inclination and is close to a right angle, and has a good shape characteristic of specular reflection light with high kurtosis. On the other hand, the solid-line specular reflection light is due to an oblique specular reflection surface having a large vertical inclination, and has low kurtosis and the shape characteristics of the specular reflection light are impaired.

  If it is a broken specular reflected light having the shape characteristic of the specular reflected light, it can be distinguished from the diffuse reflected light by the threshold value judgment regarding the kurtosis of the received light waveform. On the other hand, the solid-line specular reflection light has a shape similar to that of diffuse reflection light and is difficult to distinguish by kurtosis. Even if such a light reception waveform of the specular reflection light is normalized by the maximum light reception amount (see FIG. 11) of the light reception waveform of 130 mm, and the whole light reception waveform is raised as shown in FIG. A part is included in the prohibited area, and it can be determined that this received light waveform is due to ambient light. Note that the horizontal axis x in FIG. 15 indicates the pixel number, and the vertical axis indicates the ratio of the received light waveform of 130 mm to the maximum received light amount.

  As described above, the human body detection sensor 1 of the present example depends on whether or not the received light waveform is included in the prohibited area, in addition to the distance measurement determination routine that detects the presence or absence of the detection target using the incident position of the reflected light. A prohibited area determination routine that eliminates disturbance light can be executed. For example, the combined reflected light in which a plurality of reflected lights simultaneously generated at a plurality of locations on the bowl surface 150 are superimposed may be displaced in the detection area and may not be excluded by the distance measurement determination routine. According to the prohibited area determination routine, such combined reflected light can be detected with high accuracy and excluded as a non-detection target.

  Thus, especially the human body detection sensor 1 of this example is a sensor in which the erroneous detection by the reflected light by the bowl surface 150 is suppressed, and the detection performance is improved. The faucet 16 provided with the human body detection sensor 1 is an excellent product with few malfunctions.

In this example, the first and second prohibited area determination routines are executed. The first prohibited area determination routine is a determination routine that directly uses the amount of light received that forms the light reception waveform of reflected light. On the other hand, the second prohibited area determination routine is a determination routine that normalizes and uses the amount of light received that forms the light reception waveform of the reflected light. Executing both the first and second prohibited area determination routines is not an essential requirement of the present invention, and either one may be omitted.
In the prohibited area determination routine of this example, the acquisition of the received light waveform is executed once. It is also possible to execute the acquisition of the received light waveform a plurality of times and apply the prohibited area determination routine for each received light waveform.

In this example, five pixels are selectively set as specific pixels in the non-detection area. The number of specific pixels is not limited to the five pixels in this example. The number may be less than 5 pixels, or all the pixels forming the prohibited area may be set as specific pixels.
In this example, when the received light waveform is normalized, the entire received light waveform is normalized (see FIG. 15), but only the received light amount of a specific pixel may be normalized. Further, in this example, normalization is performed with the maximum amount of received light of the 130 mm received light waveform in FIG. 11, but normalization may be performed with the total amount of received light.

  In this example, the measured light reception waveform (FIG. 11) is used to set the prohibited area. However, the prohibited area may be set only by simulation, and the prohibited area is set by using both experiments and simulation. May be. In the case of simulation, it is preferable to determine the maximum received light amount of the received light waveform based on the reflectance, surface roughness, and the like.

  In this example, when the incident position of the reflected light is specified, the barycentric position of the received light waveform is obtained. Instead of the position of the center of gravity, the peak position of the received light waveform may be specified as the incident position. Furthermore, in this example, the center of gravity position is calculated by simple calculation. However, if there is a margin in calculation processing capacity, the center of gravity position may be calculated mathematically strictly.

  In addition, although this example is an example which applied the human body detection sensor 1 to the faucet 16 of the washstand 15, the faucet for kitchens may be sufficient. Furthermore, it is also possible to apply the human body detection sensor 1 of this example as a sensor of an automatic water supply device for a toilet bowl with an automatic cleaning function. Furthermore, the human body detection sensor 1 of this example can also be applied to various automatic devices such as a hand-holding operation and lighting or automatic doors that automatically turn on in response to a human body.

In this example, the sensor unit 2 and the control unit 3 are configured separately. Instead of this, the sensor unit 2 and the control unit 3 may be configured integrally and accommodated in the faucet 16.
Moreover, although the human body detection sensor 1 of this example contains the water supply control part 33, the water supply control part 33 can also be comprised separately.

  As described above, specific examples of the present invention have been described in detail as in the embodiments. However, these specific examples merely disclose an example of the technology included in the scope of claims. Needless to say, the scope of the claims should not be construed as limited by the configuration, numerical values, or the like of the specific examples. The scope of the claims includes techniques obtained by variously modifying or changing the specific examples using known techniques, knowledge of those skilled in the art, and the like.

DESCRIPTION OF SYMBOLS 1 ... Human body detection sensor, 15 ... Wash-stand, 150 ... Bowl surface, 16 ... Water faucet (automatic water faucet), 11 ... Solenoid (water supply control means), 12 ... Water supply piping, 2 ... Sensor unit, 25 ... Light emission part, 251 ... LED element, 26 ... imaging part, 260 ... pixel, 261 ... line sensor (imaging element), 263 ... light receiving area, 3 ... control unit, 30 ... control board, 31 ... imaging control part, 311 ... imaging control means, 312 ... Reading means, 32 ... Detection processing section, 321 ... Determination means, 322 ... Prohibition means, 324 ... Detection determination means, 325 ... Detection output means, 33 ... Water supply control section

Claims (5)

An image pickup unit including an image pickup device in which pixels are arranged one-dimensionally or two-dimensionally, and a light-emitting unit arranged offset in a predetermined direction with respect to the image pickup unit, and the light projected by the light-emitting unit A human body detection sensor for detecting a detection target located within a range of a predetermined detection distance when the imaging unit receives the generated reflected light,
Imaging control means for controlling an imaging operation in which light emission by the light emitting unit and light reception by the imaging unit are performed;
Reading means for reading the received light amount of the pixels constituting the image sensor;
The incident position of the reflected light in a light receiving area that is an area in which pixels constituting the image sensor are arranged in the predetermined direction is specified, and in the detection area corresponding to the predetermined detection distance in the light receiving area Determining means for determining that there is a detection target when the incident position belongs;
When the light reception amount of at least one specific pixel in the non-detection area outside the detection area in the light reception area is a non-detection target when the light reception amount exceeds a threshold set in advance for each pixel A prohibition means for judging,
Detection determination means for determining whether the detection target is detected or not detected,
When it is determined by the determination unit that there is a detection target, the detection determination unit determines that the detection is not detected by the prohibition unit. A human body detection sensor that, when determined to be present, determines non-detection regardless of the presence or absence of the determination result by the determination means and the content of the determination result.   In Claim 1, in the range in which the received light amount of the specific pixel is distributed, a prohibited area is provided in which the possibility that the received light amount is less likely to be distributed when the reflected light to be detected is received. The threshold used for threshold determination is a human body detection sensor which is the amount of received light that forms the lower limit boundary of the prohibited area. In Claim 1 or 2, the specific pixel is one or a plurality of pixels in a non-detection area farther than the detection area,
The threshold corresponding to the specific pixel is set based on the received light amount of the pixel located at the far end of the detection area having a predetermined maximum value and having a normal distribution. Detection sensor.   4. The inhibition unit according to claim 3, wherein the prohibiting unit normalizes the received light amount forming the actual received light amount distribution of the light receiving area using the received light amount forming the reference normal distribution, and thresholds the normalized received light amount. A human body detection sensor that executes a determination. A faucet that discharges water into a bowl with a drain at the bottom;
The human body detection sensor according to any one of claims 1 to 4,
An automatic water faucet comprising: a water supply control means for executing switching of water discharge / stop of water or adjustment of the water discharge amount in accordance with a detection signal of the human body detection sensor.

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