JPS5941528B2 - Photoelectric detection device for object passage detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an outdoor-installed object passage detection photoelectric device that has a light emitter and a light receiver arranged opposite each other and detects an object passing between the light emitter and the light receiver. The present invention relates to a detection device, and in particular to an anti-fogging device thereof.

For this type of outdoor photoelectric detection device, it is generally desired that the photoelectric detection function will not be impaired by the adhesion of rain, snow, dew, etc. The following methods are available to prevent fogging due to adhesion. (1) A method of indirectly heating the lenses of the emitter and receiver, or the protective glass provided in front of them, by air heating.

゜) A method of directly heating the glass surface by using glass with a heater as the protective glass provided in front of the emitter and receiver.

In addition, as a method of controlling the heating source in these methods,
(a) A method of controlling the temperature of the lens of the light emitter and light receiver of a photoelectric detection device or the protective glass in front thereof to be higher than the outside temperature by a certain value or more.

(b) A method of controlling so that the difference between the temperature of the protective glass of the lens of the light emitter and light receiver of the photoelectric detection device or the front surface thereof and the temperature of the hot bed is equal to or higher than a certain value.

and so on.

The anti-fogging method using these combinations does not detect fogging directly optically but indirectly by temperature difference, so fogging cannot be detected reliably, and the control described in item (a) is not effective. This method has disadvantages such as long response time, so
If the amount of light received suddenly decreases due to the accumulation of rain, snow, dew, etc., especially the sudden dew condensation that occurs when a warm front suddenly passes, this has the disadvantage of causing malfunction of photoelectric detection.

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoelectric detection device that eliminates the above-mentioned drawbacks, reliably detects fogging, prevents fogging with a short response time, and prevents functional failure.

In order to achieve such an object, the present invention provides a photoelectric detection device that has a light emitter and a light receiver arranged opposite to each other and detects an object passing between the light emitter and the light receiver. A glass plate with a heater is arranged to cover the front surface of the light emitter and the light receiver, and a lower limit value of the amount of light received by the light receiver is set, and this lower limit value of the amount of light received is compared with the amount of light received by the light receiver. a light amount detection circuit that transmits a detection output when the amount of light received by the light receiver is equal to or less than the lower limit of the amount of light received; an output for determining the presence or absence of the object detected by the light receiver; and a detection circuit for detecting the amount of light received. and a fogging detection circuit that generates a fogging detection output when both the presence/absence discrimination output indicating the absence of the object and the detection output are established, the fogging detection output of the fogging detection circuit The heater of the heater-equipped glass is energized to a heating state based on the following.

The present invention will be explained in detail below with reference to the drawings.

The drawing shows one embodiment of a photoelectric detection device according to the present invention.

In the figure, numeral 1 indicates a light emitter box, and this light emitter box 1 includes:
Inside thereof, a large number of light emitters 2 each consisting of a light emitting element 3, a lens barrel 4, a lens 5, etc. are arranged in a row in the vertical direction. In front of each light emitting device 2, a protective glass plate 6 with a heater is provided so that it can be heated electrically, or has a built-in heater wire or a resistive film such as SnO2 on its surface. On the other hand, the reference numeral 7 indicates a light receiver box, and inside the light receiver box 7, a light receiver 8 consisting of a light receiving element 9, a lens barrel 10, a lens 11, etc. is arranged opposite to each of the light emitters 2. A protective glass plate 12 with a heater, similar to that provided inside the light emitter box 1, is arranged on the side of the light emitter box 1 of each light receiver 8.

The photoelectric detection device configured in this manner is installed outdoors and is used, for example, to detect the passage of a vehicle 13 as shown in the figure. A received light amount detection circuit 14 for controlling the heater-equipped glass is connected to a specific light receiver 8 among these light receivers 8 .

The received light amount detection circuit 14 detects the amount of light received by the light receiver 8 with respect to the lower limit value of the amount of light received, which is set in consideration of the normal operation limit value of the light receiver 8.
This is to detect whether the amount of received light is above or below this lower limit value, and can be configured with a Schmitt trigger circuit, for example, and detects if the amount of received light falls below the lower limit value due to rain, snow, dew, etc. produces an output 15. Each light reception output of the light receiver 8 is supplied to a vehicle presence/absence discrimination circuit, for example, an AND gate 16, and its discrimination (AND) output 17 is used as the detection output 1 described above.
5 and a fog detection circuit, for example, an AND game port 8VC is supplied. The fogging detection output 19 obtained from the fogging detection circuit 18 is added to the heater-equipped glass control relay 20, and this relay 20
The heaters for the protective glass plates 6 and 12 are turned on and off according to the output of the heater. Here, the adhesion of rain, snow, dew, etc.
When the amount of light received by the light receiver 8 becomes equal to or less than the predetermined lower limit value, a detection output 15 is obtained from the received light amount detection circuit 14.

Moreover, at this time, when the vehicle presence/absence discrimination circuit 16 determines that the amount of light received by all the light receivers 8 is not detecting the detected object 13 such as a vehicle, the outputs 15 and 17
A fogging detection output 19 is obtained from the fogging detection circuit 18, and the heater-equipped glass control relay 20 is energized by this output 19VC, so that the heater-equipped protective glass plates 6 and 12 are heated. By such heating, the protective glass plates 6 and 121
When the fine water droplets adhering to fC are evaporated and the transparency of these protective glass plates 6 and 12 is restored and the amount of light received by the light receiver 8 exceeds the above-mentioned lower limit value, the detection output 15 can no longer be obtained from the amount of received light detection circuit 14. , the relay 20 is therefore deenergized and the protective glass plates 6 and 12 return to their unheated state. In the above example, a plurality of light emitters 2 and a plurality of light receivers 8 are provided, but the present invention is not limited to this example. In this case, the output of the light receiver 8 may be directly added to the fogging detection circuit together with the above-mentioned detection output 15 without passing it through the vehicle presence/absence determination circuit 16.

That is, the vehicle presence/absence determination circuit 16 can be omitted. As is clear from the above, according to the present invention, the protective glass plates 6 and 12 with heaters are respectively provided in front of a large number of light emitters 2 and light receivers 8 arranged in a row in the vertical direction, and these light receivers 8 Among these, by connecting the received light amount detection circuit 14 for controlling the protective glass with a heater to a specific light receiver, fogging can be directly detected and the heating of the protective glass plates 6 and 12 with a heater can be controlled. You can get an effect like this. (1) It can reliably detect cloudy weather, and the response time for cloudy detection is short. It can respond quickly enough to condensation to prevent functional failure.

(2) The structure is simple because it is only necessary to add the received light amount detection circuit 14 and combine it with the vehicle presence/absence determination circuit, and there is no need to separately provide a light emitter and a light receiver for measuring the amount of light.

(3) Since it reliably detects fogging, there is no unnecessary heating when there is no fogging, and it also has the advantage of low power consumption because it directly heats the glass surface where the moisture that causes fogging is attached.

[Brief explanation of the drawing]

The figure is a diagram showing the configuration of one embodiment of a photoelectric detection device according to the present invention. DESCRIPTION OF SYMBOLS 1... Light emitter box, 2... Light emitter, 3... Light emitting element, 4, 10... Lens barrel, 5, 11... Luns, 6, 12
・・Protective glass plate with chemical filter, 7・・Receiver box, 8・・
- Light receiver, 9... Light receiving element, 13... Vehicle, 14.
...Received light amount detection circuit, 15...Detection output, 16...Vehicle presence/absence discrimination circuit, 17...Discrimination output, 18...Fog detection circuit, 19...Fog detection output, 20...Heater Glass control relay.

Claims (1)

[Claims] 1. In a photoelectric detection device that has a light emitter and a light receiver arranged opposite to each other and detects an object passing between the light emitter and the light receiver, the light emitter and the light receiver are each covered with a front face thereof. A lower limit value of the amount of light received by the light receiver is set on the glass plate with a heater provided, and this lower limit value of the amount of light received is compared with the amount of light received by the light receiver, and the amount of light received by the light receiver is determined as the lower limit of the amount of light received. A received light amount detection circuit that transmits a detection output when the amount of received light is equal to or less than a value, an output for determining the presence or absence of the object detected by the light receiver, and a detection output of the received light amount detection circuit are provided, and the detection output of the received light amount detection circuit is provided. a fogging detection circuit that generates a fogging detection output when both the presence/absence determination output and the detection output are established, and the heater of the heater-equipped glass is set to a heating state based on the fogging detection output of the fogging detection circuit. A photoelectric detection device for detecting the passage of an object, characterized in that it is energized.