JP2000067370A - Vehicle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vehicle detector using near infrared light for accurately performing the number measurement and speed measurement of traveling vehicles. SOLUTION: This vehicle detector is constituted of a light emission part 12 driven by a driver part 2 connected to a pulse modulation signal generation part 1, a first light reception part 13 - an (n)-th light reception part 15 for receiving the reflected waves of light radiated by the light emission part 12, a first difference detection part 19 - an (n)-th difference detection part 21 for extracting only pulse components from the output of the first - (n)-th light reception parts 13-15, an absolute level comparison part 37 for detecting the vehicle by A/D converting and level-comparing the output of the first - (n)-th difference detection parts 19-21, an absolute addition value comparison part 38 for A/D converting, adding and level-comparing the output of the difference detection parts 19-21 and a passing speed detection part 39 for detecting the speed of the vehicle from the time difference of reflected light from the vehicle detected in the first light reception part 13 and the reflected light from the vehicle detected in the (n)-th light reception part 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle detection device for detecting the presence of a traveling vehicle.

[0002]

2. Description of the Related Art FIG. 12 is a block diagram showing the configuration of a conventional vehicle detection device, and FIG. 13 is an explanatory diagram of the operation of FIG. In the figure, reference numeral 1 denotes a pulse modulation signal generating unit for generating a pulse modulation signal, 2 denotes a driver unit for turning on and off a current by an output of the pulse modulation signal generating unit 1, and 3 denotes a single LED that emits a single LED according to the current of the driver unit 2. A light receiving section 4 for receiving light reflected from the vehicle or the road surface of the light from the light emitting section 3 and converting the light into a voltage; 5 a DC removing section for removing disturbance light components from a signal from the light receiving section 4; Is a signal amplifier for comparing the signal from the amplifier 6 with a reference voltage, and 8 outputs a vehicle detection signal from the comparison result of the signal comparator. A vehicle detection unit 9 is a main propagation path of light from the light emitting unit 3, a propagation path 10 from which light from the light emitting unit 3 is reflected on a vehicle or a road surface to a light receiving unit, and 11 is a passing vehicle.

Next, the operation will be described. In FIG. 12, the operation of the light emitting unit is a repetition of light emission and non-light emission shown in FIG. The light emitted from the light emitting unit 3 is collected and reflected by the passing vehicle 11 or the road surface via the main propagation path 9 shown in FIG. The reflected light is diffused and enters the light receiving unit 4 shown in FIG. 12 via the main propagation path 10 shown in FIG. The light incident on the light receiving unit 4 is a signal shown in FIG. 13B because extraneous light such as sunlight is superimposed thereon. FIG.
In FIG. 12B, a is a light receiving unit 4 for reflected light when the light emitting unit of FIG. 12 emits light.
12 shows the output voltage of the light emitting unit 4 of the reflected light when the light emitting unit is not emitting light in FIG. In the DC removing unit 5 of FIG.
The DC component due to the disturbance light shown in FIG. When the vehicle 11 passes through the output of the DC removing unit 5, the output of FIG.
The waveform is as shown in FIG. In FIG. 13C, C indicates the reflection level of the road surface, and D indicates the reflection level from the vehicle 11. FIG.
The signal comparing unit 7 of FIG. 2 compares the reflection level with a reference value E preset to a value higher than the reflection level c of the road surface shown in FIG. And The vehicle detection unit 8 makes the vehicle detection signal significant when the vehicle is present, and prevents the detection signal from being broken by retaining the signal.

[0004]

Since the conventional vehicle detection device is constructed as described above, the reflection level becomes less than the reference value in a portion of the vehicle, such as a glass surface, where light is not reflected so that vehicle detection can be performed accurately. There was a case that could not be done.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to accurately detect a vehicle.

[0006]

According to the present invention, there is provided a vehicle detecting device comprising: a light emitting means for turning on and off a light emission; and a plurality of light receiving means for receiving light reflected from a target object emitted from the light emitting means. A difference detection unit that outputs a difference between reception signals of the light receiving unit when the light emission of the light emission unit is on and off; a level comparison unit that compares an output signal of the difference detection unit with a reference value; Vehicle detection means for detecting a vehicle based on an output signal of the comparison means, wherein the vehicle detection means makes the vehicle detection output significant when the output signal of the difference detection means is larger than a reference value, and The output holding period is extended.

Further, the vehicle detecting device of the present invention includes a light emitting means for turning on and off a light emission, a plurality of light receiving means for receiving light reflected from a target object of light emitted from the light emitting means, and a light emitting means. Difference detecting means for outputting a difference between the reception signals of the light receiving means when the light emission is turned on and off, adding means for adding the output signals of the difference detecting means, and comparing the output signal of the adding means with a reference value. An addition value comparison unit; and a vehicle detection unit that detects a vehicle based on an output signal of the addition value comparison unit. The vehicle detection unit outputs a vehicle detection output when the addition value of the addition unit is larger than a reference value. This is made significant and the holding period of the detection output is extended.

[0008] The vehicle detection device of the present invention, the light emission on,
Light emitting means to be turned off, and a plurality of light receiving means for receiving reflected light from a target object of light emitted from the light emitting means,
Difference detecting means for outputting a difference between the reception signals of the light receiving means when the light emission of the light emitting means is on and off, addition means for adding the output signals of the difference detection means, and a reference value for the output signal of the addition means. Addition value comparing means for comparing with
A level comparing means for comparing an output signal of the difference detecting means with a reference value, and a vehicle detecting means for detecting a vehicle based on an output signal of the added value comparing means or an output signal of the level comparing means. When the output value of the difference detection means or the addition value of the addition means is larger than the reference value, the vehicle detection means makes the vehicle detection output significant and extends the holding period of the detection output. .

Further, the vehicle detecting device of the present invention is provided with a passing speed detecting means for calculating a passing speed of the vehicle based on an output signal of the difference detecting means.

The vehicle detecting device according to the present invention is configured such that the level comparing means compares the output value of the difference detecting means with a predetermined positive reference value and a predetermined negative reference value, respectively. When the output value of the difference detecting means is larger than the reference value, the vehicle is detected as a vehicle.

In the vehicle detecting apparatus according to the present invention, the added value comparing means compares the added value of the adding means with a predetermined positive reference value and a predetermined negative reference value, and further serves as the vehicle detecting means. When the added value of the means is larger than the reference value, it is detected as a vehicle.

The vehicle detecting apparatus of the present invention has a light receiving area selecting means for varying a light receiving area depending on which output of the plurality of light receiving means is significant in the vehicle detecting means.

Further, in the vehicle detecting device according to the present invention, the light emitting means includes a pulse modulation signal generating section, a driver section for turning on and off a current in synchronization with the pulse modulation signal, and a light emitting section driven by the driver section. The difference detection means is configured to take a signal difference at the timing of the pulse modulation signal generation section.

The vehicle detecting apparatus according to the present invention is provided with a signal switching section which is connected to an output stage of the difference detecting means and switches an output signal of the difference detecting means at the timing of the pulse modulation signal generating section.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a vehicle detection device according to the present invention, FIG. 2 is a diagram illustrating the structure, and FIG.
Is the same as the conventional device. 12 is a plurality of LEDs
The first light emitting units 13 to 15 which are turned on and off simultaneously by the driver unit 2 are first to n-th light receiving units which receive the light from the first light emitting unit 12 and the reflected light from the vehicle 11 or the road surface and convert the light into a voltage. , The light receiving sections 16 to 18 respectively increase the output from the first to n-th light receiving sections.
The amplifiers 19 to 21 take the difference between the ON and OFF states of the first light emitting unit 12 in order to remove the influence of extraneous light from the outputs of the first to n-th amplifiers 16 to 18. The first to n-th difference detectors 22 are the first to n-th difference detectors 19.
, An A / D conversion unit for digitizing the signal from the signal switching unit 22, and a signal switching unit 24 from the A / D conversion unit 23 for digitizing the signal from the signal switching unit 22. A level comparison unit that compares the signal with a preset reference voltage detects the presence / absence of a vehicle from the comparison result of the level comparison unit and adds a hold for preventing a vehicle detection signal from cracking. Reference numerals 26 to 28 denote propagation paths of light incident on the first to n-th light receiving units 13 to 15, respectively. 2A shows a plan view of the arrangement of the light receiving elements in the first to n-th light receiving sections 13 to 15, FIG. 2B shows a side view thereof, and FIGS. First to n-th light receiving units 13, 14, 15
The first to n-th light receiving elements corresponding to (1), (2) and (32) are condensing lenses for condensing light.

Next, the operation will be described. In FIG. 3A, in order to avoid interference of light with an adjacent oblique line, a pause time twice as long as the n light emission pulses is taken every n light emission pulses. In adjacent diagonal lines, synchronization is made so as to emit n light emission pulses during this pause time. Based on the pulse-modulated signal shown in FIG. 3A, a light-emitting unit composed of a plurality of LEDs and having an irradiation area of about 2 m emits and does not emit light at the same time. This light is reflected from the passing vehicle 11 or the road surface and is added to disturbance light such as reflection of sunlight, and the first to n-th light is arranged as shown in FIG.
To the light receiving elements 29 to 31 from the propagation paths 26 to 28. The incident light is converted into a voltage by the first to n-th light receiving units 13 to 15 and becomes a signal as shown in FIGS.

Here, b indicates the reflection level of disturbance light such as sunlight, and a indicates the reflection level of light from the light emitting section 12. First
From the first to n-th light receiving units 13 to 15
3C, and only the component (a) in FIG. 3C is extracted by the first to n-th difference detectors 19 to 21. At this time, by calculating A using the value of B immediately before measuring the incident level, it is possible to remove the influence of the change of the disturbance light such as a fluorescent lamp. Next, the signal switching unit 2
In step 2, the signal to be A / D converted for each light emission is time-divisionally switched from the first to the second and the outputs of the n-th difference detectors 19 to 21.

Thus, the first to n-th devices installed on the road
Signal lines from the difference detection units 19 to 21 to the part after the A / D conversion unit 23 installed on the roadside can be reduced. The switched signal is held until it is switched to the output from the difference detection unit of the next light receiving unit. This output is shown in FIG. Here, C is the reflection level from the road surface, D is the reflection level from the vehicle, and E is the reflection level averaged only every 5 seconds when the vehicle detection output is insignificant and the road surface level is measured. Is the comparison reference level. The level comparing section 24 compares the reflection level obtained by digitizing the output of the signal switching section 22 with the A / D converter 23 with the reference level E. The first vehicle detection unit 25 makes the vehicle detection output significant when the reflection level exceeds the reference plane,
By adding a hold time of 00 ms to prevent the output from being broken when no light is emitted, the vehicle detection output is output so as not to turn off the vehicle detection output in a portion with extremely low reflection such as a windshield of the vehicle. Approximately 2 m
By setting the area as the light receiving area, detection by the glass is not eliminated, and the vehicle can be detected stably.

Embodiment 2 FIG. 4 is a block diagram of another embodiment, and FIG. 5 is an operation explanatory diagram. 4, the same reference numerals denote the same functions as those of the conventional and the first embodiment. 33
Denotes a signal adder for adding the output from the A / D converter 23 to the first to n-th light receiving elements 29 to 31, and 34 denotes an adder / comparator for comparing the signal from the signal adder 33 with a reference value. The output of the signal switching unit in FIG.
Same as (f). The output of the signal switching unit 22 is digitized by the A / D conversion unit 23, and the signals from the first to n-th difference detection units 19 to 21 are added by the signal addition unit 33.
FIG. 5B shows the output of the signal adding unit 33. Here, nu is the total value of the additions from 〜 to リ. Is a reference value of the sum of the road surface level and the default value, as in the first embodiment. The addition value comparison unit 34 compares the output of the signal addition unit with the reference value. The first vehicle detection unit performs the same processing as in the first embodiment to detect the presence of a vehicle. By summing the outputs of all the light receiving elements, the same effect is obtained as when the light receiving area is increased by n times, and the S / N is improved.

Embodiment 3 FIG. 6 is a block diagram of another embodiment. 6, the same reference numerals denote the same functions as in the first and second embodiments. Reference numeral 35 denotes a vehicle detection unit which outputs a vehicle detection significance when one of the vehicle detection significance signal from the level comparison unit 24 and the vehicle detection significance signal from the addition comparison unit 34 is significant, and adds and retains the information. The level comparison improves the S / N by not using a signal from the light receiving element that is meaningless for detection, and the added value comparison has the advantage of improving the S / N by enlarging the light receiving area. Therefore, the vehicle can be accurately detected.

Embodiment 4 FIG. FIG. 7 is a block diagram of another embodiment, and FIG. 8 is an explanation of this. 7, the same reference numerals denote the same functions as in the third embodiment. 36 is the first
The time t from when the output of the light receiving unit 13 reaches the vehicle detection significant level to when the output of the nth light receiving unit 15 reaches the vehicle detection significant level is measured, and the detection area of the first light receiving element 29 and the nth Is a passing speed detecting unit that calculates the speed v of the passing vehicle by dividing the distance x of the detection area of the light receiving element 31 by this time.

Embodiment 5 FIG. 9 is a block diagram of another embodiment, and FIG. 10 is an explanation of this. In FIG. 9, the same symbols indicate the same functions as in the fourth embodiment. 37 is A /
When the output from the D conversion unit is equal to or lower than the road surface level, an absolute level comparison unit that performs the same processing as the first level comparison unit, assuming that there is an output equal to or higher than the road surface corresponding to the absolute value level, 38 When the output of the addition unit is equal to or lower than the road surface level, an absolute addition value comparison unit that performs the same processing as described above and performs the same processing as that of the first addition and comparison unit. This is a passing speed detecting unit. In FIG. 10B, the broken line is the absolute level, the solid line is the actual output, and the vehicle detection is significant when the absolute level exceeds the reference value E. As a result, a vehicle that absorbs light, such as a black vehicle, can be accurately detected.

Embodiment 6 FIG. FIG. 11 is a block diagram of another embodiment. In FIG. 11, the same reference numerals indicate the same functions as in the fifth embodiment. Reference numeral 40 denotes an area selection unit for selecting which of the first to n-th light receiving elements is used for vehicle detection, and is configured by a switch or the like. Thereby, the area in the vehicle traveling direction of the vehicle detection area can be adjusted depending on which part of the light receiving elements in the light receiving element configuration of FIG. 2 is enabled, and the area can be set arbitrarily to some extent regardless of the installation. It can be easily replaced with another type of vehicle detection device.

[0024]

As described above, according to the present invention, the use of a plurality of light-receiving portions has an effect that the vehicle detection area is widened and vehicle detection can be accurately performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a light receiving element structure of the present invention.

FIG. 3 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

FIG. 5 is an operation explanatory diagram of Embodiment 2 of the present invention.

FIG. 6 is a block diagram showing a third embodiment of the present invention.

FIG. 7 is a block diagram showing a fourth embodiment of the present invention.

FIG. 8 is an operation explanatory view of Embodiment 4 of the present invention.

FIG. 9 is a block diagram showing a fifth embodiment of the present invention.

FIG. 10 is an operation explanatory view of Embodiment 5 of the present invention.

FIG. 11 is a block diagram showing a sixth embodiment of the present invention.

FIG. 12 is a block diagram showing a conventional vehicle detection device.

FIG. 13 is an operation explanatory diagram of a conventional vehicle detection device.

[Explanation of symbols]

1 pulse modulation signal generator, 2 driver, 3 second
Light-emitting section, 4 light-receiving section, 5 DC removing section, 6 amplification section,
7 signal comparison unit, 8 vehicle detection unit, 9 main propagation path, 10
Propagation path, 11 passing vehicle, 12 first light emitting unit, 13
1st light receiving section, 14 2nd light receiving section, 15 nth light receiving section, 16 1st widening section, 17 2nd widening section, 18
N-th amplification section, 19 1st difference detection section, 20 2nd
, A difference detection unit, an n-th difference detection unit, a 22 signal switching unit, an A / D conversion unit, a 24 level comparison unit,
1st vehicle detection part, 26 1st propagation path, 27 2nd propagation path, 28 nth propagation path, 29 1st light receiving element,
30 second light receiving element, 31 nth light receiving element, 32
Condenser lens, 33 signal addition unit, 34 addition value comparison unit,
35 second vehicle detecting section, 36 first passing speed detecting section, 37 absolute level comparing section, 38 absolute adding value comparing section, 39 second passing speed detecting section, 40 area selecting section.

Claims (9)

[Claims] A light emitting means for turning on and off light emission;
A plurality of light receiving means for receiving reflected light from a target object of light emitted from the light emitting means, and a light detecting means for outputting a difference of a reception signal of the light receiving means when light emission of the light emitting means is on or off; A level comparing means for comparing the output signal of the difference detecting means with a reference value, and a vehicle detecting means for detecting a vehicle based on the output signal of the level comparing means, wherein the vehicle detecting means further comprises: A vehicle detection device, wherein when the output signal of the means is larger than a reference value, the vehicle detection output is made significant and the holding period of the detection output is extended for a predetermined time. 2. A light emitting means for turning on and off light emission,
A plurality of light receiving means for receiving reflected light from a target object of light emitted from the light emitting means, and a light detecting means for outputting a difference of a reception signal of the light receiving means when light emission of the light emitting means is on or off; Addition means for adding the output signal of the difference detection means, addition value comparison means for comparing the output signal of the addition means with a reference value, and vehicle detection means for detecting a vehicle based on the output signal of the addition value comparison means. With
Further, when the added value of the adding means is larger than a reference value, the vehicle detecting means makes the vehicle detected output significant, and extends a holding period of the detected output for a predetermined time. . 3. A light emitting means for turning on and off light emission,
A plurality of light receiving means for receiving reflected light from a target object of light emitted from the light emitting means, and a light detecting means for outputting a difference of a reception signal of the light receiving means when light emission of the light emitting means is on or off; An addition unit that adds the output signal of the difference detection unit, an addition value comparison unit that compares the output signal of the addition unit with a reference value, and a level comparison unit that compares the output signal of the difference detection unit with a reference value. A vehicle detecting means for detecting a vehicle based on an output signal of the added value comparing means or an output signal of the level comparing means, wherein the vehicle detecting means further comprises an output value of the difference detecting means or an added value of the adding means. Is larger than the reference value, the vehicle detection output is made significant, and the holding period of the detection output is extended by a predetermined time. 4. The vehicle detecting device according to claim 1, further comprising a passing speed detecting means for calculating a passing speed of the vehicle based on an output signal of said difference detecting means. 5. The level comparing means compares the output value of the difference detecting means with a preset positive reference value and a predetermined negative reference value, respectively. 4. The vehicle detecting device according to claim 1, wherein the vehicle is detected when the vehicle is larger than the reference value. 6. The addition value comparison means compares the addition value of the addition means with a preset positive reference value and a predetermined negative reference value, and further, the vehicle detection means determines that the addition value of the addition means is the reference value. The vehicle detection device according to claim 2, wherein the vehicle is detected when the value is larger than the value. 7. A light receiving area selecting means for varying a light receiving area depending on which output of said plurality of light receiving means is significant in said vehicle detecting means. The vehicle detection device according to any one of the preceding claims. 8. The light emitting means includes a pulse modulation signal generating section, a driver section for turning on and off a current in synchronization with the pulse modulation signal, and a light emitting section driven by the driver section. 4. The vehicle detection device according to claim 1, wherein a signal difference is obtained at a timing of the pulse modulation signal generation unit. 9. A vehicle detection apparatus according to claim 8, further comprising a signal switching section connected to an output stage of said difference detection means and switching an output signal of said difference detection means at the timing of said pulse modulation signal generation section. .