JP2001318163A - Optical detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical detecting device which uses a semiconductor position detecting element outputting photocurrents corresponding to an incidence position from both ends as a photodetecting element, can use a battery as its power source, is suitably used for water-concerned equipment, and detects whether or not there is an object. SOLUTION: The optical detecting device 10 has a light emitting element 12 which emits pulse light to an object to be measured, a light receiving element 18 composed of a semiconductor position detecting element outputting photocurrents IL1 and IL2 from both ends on receiving reflected light from the object, 1st and 2nd current-voltage converting capacitors C1 and C2 which convert the photocurrents from both the ends of the light receiving element 18 into voltages, and a voltage ratio detecting means which detects and compares the voltage ratios of the capacitors C1 and C2 and decides whether or not there is an object in a set distance range to output a detection signal. Here, the voltage ratio detecting means can include comparing capacitors C5 and C6, content-current discharging circuits 34 and 36, and a voltage comparing circuit 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic faucet, an automatic flush toilet, a basin, an automatic opening / closing toilet seat, a local flushing device for a toilet,
The present invention relates to an optical detection device suitable for application to a device for detecting whether or not a user is within a set distance range in automatic lighting, automatic heating, and the like.

[0002]

2. Description of the Related Art In this type of instrument, an infrared detector is used as a device for detecting whether or not an object to be measured is within a set distance range, that is, whether or not a user is within a set distance range. Conventionally, a diffuse reflection type detection device has been widely used.

FIG. 4 shows the principle diagram. This optical detection device converts light emitted from an infrared light emitting diode (light emitting element) 200 into an object to be measured (user) 20.
4, the reflected light (diffused light) is made incident on a photodiode (light receiving element) 208. In this case, if the object 204 to be measured is in a close position, the photodiode 20
8, the amount of light incident on the photodiode 208 decreases when the measurement object 204 is farther. By utilizing this, that is, the distance of the measurement object 204 can be determined according to the magnitude of the amount of reflected light incident on the photodiode 208.

However, in the case of the infrared diffuse reflection type optical detection apparatus, the color of the object 204 to be measured depends on the color of the object 204 to be measured.
Specifically, depending on the color of the clothes worn by the user,
There is a problem that the amount of light incident on the photodiode 208 greatly changes.

For example, when the color of the measurement object 204 is white, the amount of reflected light incident on the photodiode 208 increases, and when it is black, the photodiode 208
, The amount of reflected light incident on the surface becomes smaller. Therefore, if the distance is adjusted in the case of white, when the measuring object 204 is black, the amount of reflected light incident on the photodiode 208 is too small, and the measuring object 204 is not moved even though the measuring object 204 is at the same distance. It cannot be detected.

On the other hand, as an optical detecting device, a semiconductor position detecting element (P) that outputs a photocurrent from both ends according to the incident position.
2. Description of the Related Art An infrared distance-measuring type optical detecting device using SD (Position Scnsitivc Photo Dctcctor) is known. FIG. 5 shows the principle diagram. This optical detection device is of a “logarithmic conversion + difference extracting” system using logarithmic characteristics of a semiconductor, and pulse light emitted from a light emitting diode 200 is transmitted to a measurement target 204 through a light projecting lens (condensing lens) 202. Projected. Then, the reflected light is incident on the surface of the semiconductor position detecting element (light receiving element) 210 through the light receiving lens (condensing lens) 206 to form an image.

Here, the semiconductor position detecting element 210 is a PIN photodiode having a continuous resolution, and is a photoelectric conversion element for generating two photocurrents whose ratio is determined by the spot imaging position on the light receiving surface. The light incident on the position detecting element 210 is photoelectrically converted, and is divided and output as a photocurrent from electrodes provided at both ends. That is, when the spot light is incident on the semiconductor position detecting element 210, electric charge proportional to the light energy is generated at the incident position, and the generated electric charge passes through the surface layer as a photocurrent and is output from each of the electrodes at each end. . Since the resistance layer on the surface is made to have a uniform resistance value over the entire length and over the entire surface, the photocurrent is divided in inverse proportion to the distance to the electrode at each end, that is, the distance to each end. Taken out.

For example, as shown in FIG. 6A, when a spot light is incident on the central position of the light receiving surface, the semiconductor position detecting element 2
The ratio of the two photocurrents from each end of 10 is I _L1 : I _L2 = 1: 1. Further, when spot light is incident on the position at a ratio of 1: 2 from both ends as shown in FIG. 3B, I _L1 : I _L2 = 1: 2, and as shown in FIG. In the case where the spot light is incident at a position of 1: 3 from both ends, I _L1 : I _L2 = 1: 3.

Therefore, when the distance to be determined is the distance X in FIG. 5, the threshold value of the photocurrent of the semiconductor position detecting element 210 is set to I _L1 / I _L2 = a / b, and I _L1 / I _L2 is set to a / b.
If it is larger than b, the measuring object 204 is farther than X and I
_{If L1} / I _L2 is smaller than a / b, the measurement target 20
4 can be determined to be closer than X.

In the optical detection device shown in FIG. 5, as a circuit for determining the threshold value of the photocurrent ratio, the two photocurrents of the semiconductor position detecting element 210 are converted to semiconductors 212 having logarithmic characteristics such as diodes. and current-voltage conversion in 214, the value _log (I L1) corresponding to the _I L1 _{/ I L2} taking the difference between the log-transformed two voltage subtracter 216 -log
(I _L2 ), which is compared with a voltage threshold V ₀ by a comparator (microcomputer) 218 to determine the distance. For example, if the distance to be determined is X in FIG. Assuming that V ₀ is V ₀ = log (a / b), it is possible to determine whether or not the measurement object 204 is farther than X.

In the case of the optical detecting device shown in FIG. 5, since the position of the light receiving spot of the semiconductor position detecting element 210 is read, the detected value of the distance is not affected by the color of the measuring object 204, that is, the reflectance. Having. However, the optical detection device shown in FIG. 5 has a problem that it is difficult to expand its use to battery-powered portable devices because of its large power consumption.

In the case of the optical detecting device shown in FIG. 5, the photocurrent flowing out of the semiconductor position detecting element 210 is several hundred nA in the case of the object 204 having a low reflectance such as black.
In the case of the measurement object 204 having a high degree of reflectance, such as white color, the current may flow several hundred μA, and the current range greatly differs depending on the reflectance and the distance of the measurement object 204.

In the method based on "logarithmic conversion + difference extraction" in FIG. 5, when the photocurrent is small, there is a phenomenon that the time from when the photocurrent starts flowing to when the logarithmically converted voltage is generated becomes longer. This will be described with reference to FIG. 7. The photocurrents I _L1 and I _{L2 that} have begun to flow are converted by the semiconductor
Semiconductor 21 that performs logarithmic conversion before flowing through 12, 214
In order to charge the stray capacitance of the capacitor component parasitic to the circuit to which the semiconductors 212 and 214 are connected, even when the voltages of the semiconductors 212 and 214 are observed, a logarithmically converted voltage value cannot be obtained.
(Unstable time) t ₁ is present.

Assuming that the stray capacitance is C, the photocurrent is I, and the logarithmically converted voltage is V, the time t required for charging the stray capacitance C
₁ is t ₁ = V × C ÷ I (1). Since the voltage is increasing during the charging time t ₁ of the floating capacitance C, the logarithmically converted value cannot be read.

For example, in the actual measurement example of the present inventor, in FIG.
Photocurrent I in the case of the object 204 to be measured_L2= 155n
A, Diode forward voltage V at 155 nA₂{0.
36V, stray capacitance of circuit 回路 60pF, stray capacitance 0.3
Time t for charging to 6V ₁Is given by equation (1)₁= 140 μSEC, and the “light emission time” of at least 140 μSEC is
Otherwise, the logarithmically converted value cannot be read.

The current required for light emission is several tens to several hundreds of mA, which is larger than the several mA of the light receiving signal processing circuit, so that the current consumption of the entire device cannot be reduced. That is, in order to obtain a stable detection value, it is necessary to continuously emit the pulse light from the light emitting diode 200 for a long time, and at that time, large power is consumed. For this reason, an optical detection device using this type of semiconductor position detection element is:
The fact is that it is not conventionally applied to a battery-powered device.

Therefore, the present applicant has proposed an optical detection device which processes a photocurrent from a semiconductor position detecting element by another method (Japanese Patent Laid-Open No. 7-209435). FIG. 8 shows the principle diagram. This optical detection device includes a semiconductor position detecting element 21 as shown in FIG.
The two photocurrents from both ends of the zero
In this case, the amplification factor can be set only on one side of the amplifier 222, and the respective photocurrents are amplified at a ratio inversely proportional to the ratio of the distance from the set incident position to each end in the semiconductor position detection element 210. The comparator 218 compares whether or not the voltage levels are the same, thereby determining whether the ratio of the two photocurrents flowing from the semiconductor position detecting element 210 is larger or smaller than a set constant current ratio. .

However, in the case of the optical detection device shown in FIG. 8, it is necessary to avoid saturation of the amplifiers 220 and 222 in order to accurately compare the amplified signals. Therefore the maximum value of the photocurrent value I _L2 flowing out the maximum output amplitude of the amplifier 222 from the semiconductor position detecting element 210, the number that is an optical current corresponding to the high object 204 reflectance such as white hundred μ
When set to A, in the case of a low object 204 reflectance such as black because the light current _{I L2} is 1/1000, it becomes 1/1000 of the largest amplitude output of the amplifier 222.

For example, when the power supply voltage is 5 V, even if the output for a white object is set to 5 V, the output for a black object is 5 mV, which is so small that it cannot be distinguished from signal noise. Can not be compared. Therefore, in the optical detection device disclosed in Japanese Patent Application Laid-Open No. 7-209435, the amplification factor is increased so that amplification can be performed even in a state where the photocurrent is small. A circuit is incorporated into the circuit. FIG. 9 shows a specific circuit configuration.
As shown in FIG.
24 is incorporated in the circuit.

However, even in this case, the time required for lowering the light emission level, that is, the so-called negative feedback reaction time is required, and the output may be saturated during the negative feedback reaction time. It is necessary to reduce the influence even if the output is saturated during the negative feedback reaction time by integrating the light emission time by extending the light emission time or by repeating the light emission several times.

The reaction time of the negative feedback is determined by the semiconductor position detecting element 2.
Since the reaction time of 10 is 30 μSEC at the maximum, about 125 μSEC or more is necessary for the entire negative feedback circuit, and the integrated light emission time for obtaining one measurement result cannot be shorter than 125 μSEC, so that the power consumption of the entire apparatus increases. Would.

[0022]

The optical detecting device of the present invention has been devised to solve such a problem. According to the first aspect of the present invention, (a) a light-emitting element that emits pulsed light toward an object to be measured, and (b) a photocurrent is output from both ends by receiving reflected light from the object, and A light receiving element comprising a semiconductor position detecting element which proportionally reduces or increases a photocurrent from each end in accordance with the distance from the incident position of the reflected light to each end; Detecting and comparing each voltage ratio of the first and second current-voltage conversion capacitors with (d) the first and second current-voltage conversion capacitors, which converts the photocurrent from the end into a voltage;
Voltage ratio detecting means for determining the presence or absence of an object within the set distance range and outputting a detection signal.

According to a second aspect of the present invention, in the first aspect, the voltage ratio detecting means discharges the charges of the first and second current-voltage conversion capacitors at a constant current by the first and second dischargers. It is characterized in that the length of the discharge time is compared to determine the presence or absence of an object within the set distance range.

According to a third aspect of the present invention, in the second aspect, the first and second current-voltage conversion capacitors have the same capacity, and the first current-voltage conversion capacitor and the second current-voltage conversion capacitor have the same capacitance. The ratio of the discharge amount of the first and second dischargers corresponding to each of the capacitors is a ratio corresponding to a threshold of the ratio of the distance from the set incident position to each end of the light receiving element. The discharge is simultaneously terminated when light enters the set incident position.

According to a fourth aspect of the present invention, in the first aspect, the voltage ratio detecting means includes a first and a second comparison capacitor respectively corresponding to the first and the second current-voltage conversion capacitors. And at the corresponding voltage via the buffer, and then the first and second dischargers discharge the charge of the first and second comparison capacitors. .

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the optical detecting device is an automatic faucet, an automatic flush toilet, a basin, an automatic opening / closing toilet seat, a toilet local cleaning device, an automatic lighting, It is a user detection device for automatic heating.

[0027]

As described above, the optical detection device of the present invention uses the first and second current-voltage conversion capacitors as means for converting the photocurrent from each end of the semiconductor position detection element into a voltage. The voltage ratios of the first and second current-voltage conversion capacitors are compared by voltage ratio detection means to determine the presence or absence of an object within a set distance range and to output a detection signal. For example, as in the optical detection device shown in FIG. 5, that is, when the photoelectric current from the semiconductor position detecting element is converted into a voltage by logarithmic conversion by a semiconductor, the floating capacitance of a parasitic capacitor component in a circuit connected to the semiconductor is charged. Is an unstable time, and there is no problem that correct voltage ratio detection, that is, actual measurement can be performed only after that, and the detection operation can be completed in a short time.

Accordingly, the pulse emission time per pulse from the light emitting element can be shortened, and power consumption can be reduced. Therefore, according to the present invention, there is a great effect that the present invention can be applied to a detection device of a portable device using a dry battery as a power source.

Here, the voltage ratio detecting means determines the presence or absence of an object within the set distance range by comparing the length of discharge time when the electric charge of the current-voltage conversion capacitor is discharged at a constant current by the discharger. (Claim 2).

Furthermore, in this case, the first and second
Of the first and second dischargers corresponding to the first current-voltage conversion capacitor and the second current-voltage conversion capacitor, and the ratio of the discharge amount set in the light receiving element to the light-receiving element. A ratio corresponding to a threshold value of a ratio of a distance from the position to each end may be set so that the discharge is simultaneously terminated when the reflected light enters the set incident position (claim 3). By doing so, it is possible to easily and accurately detect whether or not there is an object within the set distance range by checking whether or not the discharge has been completed at the same time.

In the present invention, the voltage ratio detecting means may include:
The first and second comparison capacitors are charged with a voltage corresponding to the voltages of the first and second current-voltage conversion capacitors via a buffer, and the charges of these comparison capacitors are charged by the first and second dischargers. It can be made to discharge (claim 4). In this case, by changing the capacitances of the first and second current-voltage conversion capacitors and the first and second comparison capacitors, there is obtained an advantage that the measurement accuracy of the discharge time can be freely determined.

Further, the present invention can be suitably applied as an automatic faucet, an automatic flushing toilet, a washbasin, an automatic opening / closing toilet seat, a local cleaning device for a toilet, an automatic lighting device, and a detecting device in automatic heating. . Here, the local toilet cleaning device is
This means a device that sprays washing water from a washing nozzle to wash a local area of a toilet user.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 10 denotes an optical detection device according to the present embodiment, and reference numeral 12 denotes a light emitting element including an infrared light emitting diode for projecting a pulse light toward a measurement object. The light from the light emitting element 12 is projected on a measurement object 14 through a light projecting lens (condensing lens) 16.

Numeral 18 denotes a light receiving element comprising a semiconductor position detecting element (hereinafter abbreviated as PSD), and the reflected light from the object 14 passes through a light receiving lens (condensing lens) 22 to form the light receiving element 1.
8 is incident. The light receiving element 18 outputs, from each end, a photocurrent corresponding to the incident position, specifically, a photocurrent inversely proportional to the distance from the incident position to both ends.

FIG. 2 specifically shows a circuit configuration of the optical detection device 10. In the figure, Q1 is a transistor for driving the light emitting element 12, and R2 is a resistor for driving the transistor Q1. Further, R1 is a resistor for setting the emission current, and C7 is a capacitor for charging the emission current.

Reference numeral 20 denotes a measurement timing setting circuit for setting the measurement timing by controlling the operation timing of the transistor Q1, and capacitors C50 and C51 are connected. Here, the capacitor C50 is for setting the light emission timing (waiting time from power-on to light emission), and the capacitor C51 is for setting the light emission time (length of light emission) of the pulse light.

The light emitting element 12 emits pulse light at the timing (period) set in this way and for the set light emission time. The light pulsed from the light emitting element 12 is reflected by the measurement object 14 as shown in FIG. 1, and the reflected light is incident on the light receiving element 18 made of PSD.

As is clear from FIG. 1, the incident position is incident at a position near the lower end in the figure when the distance to the object 14 is short, and is incident at a position near the upper end in the figure when the distance is long. I do. Then, a photocurrent having a magnitude corresponding to the incident position, that is, a magnitude inversely proportional to the distance from the incident position to each end is output from each end.

The photocurrent extracted from each end of the light receiving element 18 is amplified by photocurrent amplifier circuits 23 and 24, respectively.
The first and second first-stage capacitors (current-voltage conversion capacitors) C1 and C2 are charged, respectively. The photocurrent is converted into a voltage in each of the first-stage capacitors C1 and C2. Here, the first-stage capacitors C1 and C2 have the same capacitance.

C3 and C4 are ambient light storage capacitors,
Reference numerals 6 and 28 denote ambient light cancellers, which disturb light components of the photocurrent from the light-receiving element 18 to the ambient light storage capacitors C3 and C
4, the same amount is extracted by the ambient light cancellers 26 and 28, and the voltages of the first and second first-stage capacitors C1 and C2 are held at the reference voltage as shown in FIG.

In the apparatus of this embodiment, after the photocurrent is converted into a voltage by the first-stage capacitors C1 and C2, the voltage ratio between them is detected by a voltage ratio detecting means described later, and the object 14 to be measured falls within the set distance range. It is determined whether there is.

C5 and C6 are first and second comparison capacitors respectively constituting elements of the voltage ratio detecting means.
At the same time as the charging of the first-stage capacitors C1 and C2 is started, the comparison capacitors C and
5, C6 is charged. Here, the constant current charging amplifiers 30 and 32 are amplifiers having an amplification factor of 1 and have a function as a buffer, operate only while the pulse light is emitted from the light emitting element 12, and the pulse light is emitted from the light emitting element 12. When it does not emit light, it is stopped.

The first-stage capacitors C1 and C2 and the comparison capacitors C5 and C6 are proportional to the pulse light while the light-emitting element 12 continues to emit light, that is, while the photocurrent flows into the first-stage capacitors C1 and C2. When the voltage increases and the light emission ends, the charges of the comparison capacitors C5 and C6 are discharged by the constant current discharge circuits 34 and 36 at a constant current. The comparison capacitors C5 and C6 have the same capacitance. Specifically, in this example, the comparison capacitors C5 and C6 are each set to 1000 pF.

On the other hand, the constant current discharge circuits 34 and 36 are set to different discharge amounts from each other. Specifically, in FIG. 1, the set distance range when it is determined that the object 14 is present is X, and when the object 14 is at the position of the set distance range X, the incident position on the light receiving element 18 is a / b = 3
/ 1, the discharge amount of the constant current discharge circuit 34 is set to be three times that of the constant current discharge circuit 36. That is, when the charging voltage of the comparison capacitor C5 is three times the charging voltage of the comparison capacitor C6, the discharging capabilities of the constant-current discharging circuits 34 and 36 are set so that the discharging ends simultaneously.

[0045] Thus Wakashi towards comparison capacitor C6 of the long distance side to be charged by the photocurrent I _L1 of the long distance side, faster discharge than the comparative capacitor C5 of the near side of charged by the photocurrent I _L2 of the short-range side Upon completion, it can be determined that the object 14 is within the set distance range X, that is, that the object 14 is within the set detection distance range X.

Reference numeral 38 denotes a voltage comparison circuit for monitoring and comparing the voltages of the comparison capacitors C5 and C6. As described above, the voltage comparison circuit 38 changes the voltage of the comparison capacitor C6 on the long distance side to the short distance side. When the voltage returns to the original voltage earlier than the voltage of the comparison capacitor C5, that is, when the discharge ends earlier, a signal is output, and the switching transistor 40 is turned on. Here, a detection signal indicating that the object 14 exists within the set distance range X is output.

As described above, in this embodiment, the constant current charging amplifier 3
0, 32, comparison capacitors C5, C6, constant current discharge circuits 34, 36, voltage comparison circuit 38, switching transistor 40, etc., constitute a voltage ratio detection means.
In the drawing, reference numeral 42 denotes a detection distance setting circuit, which has resistors R3 to R6 for setting the detection distance. 44 is a distance setting input terminal, and C100 is a bypass capacitor for absorbing line noise.

Next, the operation of the apparatus of this embodiment will be described in detail below with reference to the time chart of FIG. FIG. 3A shows a state when the measurement object 14 does not exist. In this case, even if the light emitting element 12 emits pulse light, reflected light does not enter the light receiving element 18, so that the first stage is not used. The capacitors C1 and C2 only hold the reference voltage, and do not cause a voltage rise due to a photocurrent generated by the incidence of reflected light. Although the comparison capacitors C5 and C6 charge the reference capacitors of the first-stage capacitors C1 and C2, respectively,
Similarly, the voltage rise due to the photocurrent generated by the incidence of the reflected light is not performed.

On the other hand, FIG. 3B shows a state in which the measuring object 14 exists within the set distance range X. In this case, the reflected light from the object 14 enters the light receiving element 18. A photocurrent corresponding to the incident position is output from both ends of the light receiving element 18. In response, the first stage capacitor C
1 and C2 increase in voltage based on the respective photocurrents.
This voltage rise is performed continuously during the time when the pulsed light is emitted.

At this time, the voltages of the comparison capacitors C5 and C6 also rise at the same time, and the constant current charging amplifiers 30 and 32 are stopped from the time when the emission of the pulse light is stopped. C6
Is performed. At this time, when the discharging of the comparison capacitor C5 and the discharging of the comparison capacitor C6 are simultaneously completed,
More specifically, when the voltages of the capacitors C5 and C6 simultaneously decrease to the original voltages indicated by the broken lines in FIG. 3B, the measurement object 14 is just within the set distance range X, that is, the light receiving element in FIG. It can be determined that a / b is incident on the position of 3/1 with respect to 18. If the discharge of the comparison capacitor C6 is completed earlier than this, the measuring object 14 is positioned within the set distance range X, that is, the set distance range X
It can be determined that there is the measurement object 14 inside.

According to the optical detecting device of the present embodiment as described above, the conventional optical detecting device shown in FIG. 5, that is, the photocurrent from the semiconductor position detecting element is converted into a voltage by logarithmic conversion by a semiconductor. In addition, the time required to charge the stray capacitance of the capacitor component parasitic to the circuit connected to the semiconductor becomes unstable, and the problem that the original voltage ratio cannot be detected for the first time does not occur. Can be completed. As a result, the pulse emission time per light emission from the light emitting element can be shortened, and power consumption can be reduced. Therefore, according to this device, a detecting device using a dry battery as a power source can be easily configured.

Conventionally, it has been difficult to use a power supply of 100 V in water-related facilities or equipment. Therefore, it has been desired to construct a detecting device using a dry battery as a power supply. It was difficult to configure the detection device used because of high power consumption.
According to the optical detection device of this example, an optical detection device using a dry cell as a power source and using a semiconductor position detection element can be easily configured, and therefore, accurately and with low power consumption without being affected by the color of an object. There is a great effect that the object can be determined and detected.

In this embodiment, the voltages of the first and second first-stage capacitors (current-voltage conversion capacitors) C1 and C2 are temporarily transferred to comparison capacitors C5 and C6, and then the comparison capacitors C5 and C6 are discharged. Since the voltage ratio is detected by observing the time required for the discharge, the presence or absence of an object within the set distance range can be detected very easily and accurately.

Although the embodiment of the present invention has been described in detail, this is merely an example. For example, in the above example, the first stage capacitor C
After transferring the voltages of C1 and C2 to the comparison capacitors C5 and C6, they are discharged. However, in some cases, the first-stage capacitors C1 and C2 are charged and then connected to the constant current discharge circuit by the switch means. Then, by discharging them and observing the time until the end of the discharge, it is possible to detect whether or not there is an object within the set distance range, or it is also possible to detect the presence of the first-stage capacitors C1 and C2. The voltage is amplified by separate amplifiers at a ratio corresponding to the threshold value, and whether or not the object is within the set distance range X is determined by checking whether or not the amplified voltage levels are the same. It is also possible in some cases to perform detection.

However, when the voltages of the first-stage capacitors C1 and C2 are amplified by the amplifier, the time required for detection becomes slightly longer. In this sense, in the above embodiment, the voltage ratio is detected by transferring the voltage to the comparison capacitors C5 and C6 without using such an amplifier. Have. In addition, the present invention can be configured in a form in which various changes are made without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an optical detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration of the optical detection device in FIG.

FIG. 3 is a time chart showing the operation of the detection device of the same embodiment.

FIG. 4 is a diagram showing an example of a conventional optical detection device.

FIG. 5 is a diagram showing an example different from FIG. 4 of the conventional optical detection device.

FIG. 6 is an operation explanatory view of a semiconductor position detection element in the optical detection device of FIG. 5;

FIG. 7 is an explanatory diagram of a defect of the optical detection device of FIG. 5;

FIG. 8 is a diagram showing an example of a conventional optical detection device which is different from FIGS. 4 and 5;

9 is a diagram showing a specific circuit configuration of the optical detection device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Optical detection apparatus 12 Light emitting element 14 Object to be measured 18 Light receiving element 30, 32 Constant current charging amplifier (buffer) 34, 36 Constant current discharging circuit 38 Voltage comparing circuit 40 Switching transistor C1, C2 First stage capacitor (current-voltage conversion capacitor) C5, C6 Comparison capacitors _IL1 , IL2 _Photocurrent X Set distance range

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) E03D 13/00 G01B 11/00 B 2H051 G01B 11/00 G01C 3/06 A G01C 3/06 G01V 9/04 J G02B 7/32 G02B 7/11 B (72) Inventor Yasuaki Kozen 5-1, Koiehonmachi, Tokoname-shi, Aichi F-term in Inax Co., Ltd. 2D037 AD16 2D038 KA01 2D039 AA01 AA04 FA04 2F065 AA06 BB05 CC16 DD06 FF09 GG07 JJ16 PP22 QQ14 QQ25 UU05 2F112 AA06 BA04 BA05 CA03 FA01 FA12 FA29 FA50 2H051 BB20 BB24 CB23 CB24 DB01

Claims (5)

[Claims] 1. A light emitting element which emits pulsed light toward an object to be measured, and b) a photocurrent is output from both ends in response to reflected light from the object and an incident position of the reflected light. A photodetector comprising a semiconductor position detecting element for proportionally decreasing or increasing the photocurrent from each end in accordance with the distance from the photodetector to each end; and (c) a photocurrent from each end of the photodetector. And (d) detecting and comparing the respective voltage ratios of the first and second current-voltage conversion capacitors to determine whether or not there is an object within a set distance range. An optical detection device, comprising: a voltage ratio detection unit that determines and outputs a detection signal. 2. The system according to claim 1, wherein the voltage ratio detecting means determines the length of the discharge time when the charge of the first and second current-voltage conversion capacitors is discharged at a constant current by the first and second dischargers. An optical detection device for comparing and determining the presence or absence of an object within the set distance range. 3. The capacitor according to claim 2, wherein the first and second current-voltage conversion capacitors have the same capacity, and correspond to the first current-voltage conversion capacitor and the second current-voltage conversion capacitor, respectively. The ratio of the discharge amount of the first and second dischargers is a ratio corresponding to a threshold value of the ratio of the distance from the set incident position to each end of the light receiving element, and the reflected light is reflected by the set incident light. An optical detection device characterized in that the discharge ends at the same time when the light enters the position. 4. The voltage ratio detecting means according to claim 1, wherein said voltage ratio detecting means corresponds to first and second comparison capacitors respectively corresponding to said first and second current-voltage conversion capacitors. An optical detection device which is charged with a voltage via a buffer and discharges the charges of the first and second comparison capacitors with the first and second dischargers. 5. The user according to claim 1, wherein the optical detection device is a user in an automatic faucet, an automatic flush toilet, a washbasin, an automatic opening / closing toilet seat, a local flushing device for a toilet, automatic lighting, and automatic heating. An optical detection device, which is a detection device according to (1).