JPH0344671B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a passing direction detection sensor that detects the direction of a passing object.

[Conventional technology]

A conventional passing direction detection sensor includes a first photo sensor and a second photo sensor each having a light source and a photodetector, and converts a detection signal of the first photo sensor and a detection signal of the second photo sensor into an object passing direction signal. The circuit includes a circuit that performs the following steps.

Next, a conventional passing direction detection sensor will be described in detail with reference to the drawings.

FIG. 5 is a block diagram showing an example of a conventional passing direction detection sensor.

The passing direction sensor shown in FIG. 5 includes a first photo sensor 51 having a light source and a photodetector, and a second photo sensor 52 also having a light source and a photodetector.
and a circuit 53 for converting the detection signal of the first photo sensor and the detection signal of the second photo sensor into an object passing direction signal.

Here, the first photo sensor 51 and the second photo sensor 52 are installed at different positions along the trajectory of the object. The direction in which the object passes is the fifth
In the case of direction A in the figure, the detection signal of the object is outputted in the order of first photo sensor 51 and then second photo sensor 52. Conversely, when the object passes in the direction B in FIG. 5, the object detection signal is output to the second photo sensor 52 and then to the first photo sensor 51 in this order. Therefore, the circuit 53 that converts the detection signals of the first photo sensor 51 and the second photo sensor 52 into passing direction signals can determine the order in which the detection signals are output and detect the passing direction.

[Problem that the invention seeks to solve]

The conventional passing direction detection sensor described above has a configuration including a first photo sensor 1 and a second photo sensor 2 having a light source and a photodetector, so it is necessary to have two light sources and supply current to both. At the same time, there was a drawback in that it was necessary to take measures such as keeping the distance between the two light sources so that the light from the two light sources did not interfere with each other.

[Means for solving problems]

The passing direction detection sensor of the present invention includes: a light source that shines light on a passing object; a first detector that detects the presence or absence of a passing object based on the presence or absence of reflection of the light;
A trapezoidal prism is located on the side opposite to the light source with respect to the trajectory of the object, and diffracts the light from the light source and directs the light to the object passing through. a second photodetector for detecting the presence or absence of an object;
The first photodetector includes a second photodetector and a circuit that converts a detection signal from the second photodetector into an object passing direction signal.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a top view showing an embodiment of the present invention.

A light source 11 that emits light to a passing object 16; a first detector 12 that detects the presence or absence of the passing object 16 based on the presence or absence of reflected light a of the light applied to the passing object 16 by the light source 11; trajectory b
A trapezoidal prism 14 is located on the opposite side of the light source and diffracts the light c from the light source and directs the light d to an object 16 passing through the trapezoidal prism 14. a second photodetector 13 that detects the presence or absence of an object, and converts the detection signal e of the first photodetector 12 and the detection signal f of the second photodetector 13 into a passing direction signal g of the object. The circuit 15 is configured to include a circuit 15.

FIG. 2 is a circuit diagram showing a detailed example of the circuit 15. In FIG. 2, the NAND gate 21 connects the detection signal e of the first photodetector 12 and the second photodetector
The NOR gate 22 inputs the detection signal f of the set/reset flip-flop 23 and outputs the set signal h of the set/reset flip-flop 23. Similarly, the NOR gate 22 inputs the detection signal e and the detection signal f and outputs the reset signal of the set/reset flip-flop 23. Output i.

FIGS. 3a and 3b show that the length n of the object 16 passing through in FIG.
Fig. 4a shows a timing chart when the distance k between the light d entering the photodetector 13 and the distance k is shorter.
b is a diagram showing a timing chart when the length n of the passing object 16 in FIG. 1 is longer than the interval k. The logic is described using positive logic, and the first detector 12 is "1" when light is received, and the second detector 13 is "1" when light is present.

The case where the passing object 16 shown in FIG. 1 moves in the direction l while the length n is shorter than the distance k will be explained using FIG. 3a. State t1 in FIG. 1 indicates a state in which the passing object 16 begins to block the light d entering the second detector 13. At this time, the detection signal e of the second detector 13 becomes "1" and is maintained until a state t2 where the passing object 16 no longer blocks the light d entering the second detector 13. Further passing object 16
moves in the direction l, and from the light source 11 to the trapezoidal prism 1
A state t3 is reached in which the reflected light a begins to enter the first detector 12 by blocking the light c entering the detector 12. The second detector 13 is "0" from state t2 to state t3, and at the same time as state t3 is reached, the detection signal e of the second detector 13 and the detection signal f of the first detector 12 are
becomes “1”. When the passing object 16 further moves in the direction l and reaches a state t4 in which it does not block the light entering the trapezoidal prism 14 from the light source 11, the detection signal e of the second detector 13 and the detection signal f of the first detector 12 becomes “0”. In the circuit diagram of Figure 2
NAND gate 21 above detection signal e and detection signal f
As shown in the timing chart in Figure 3.
The NAND output h is generated by the NOR gate 22, and the NOR gate 22 generates the NOR output i. Since the rise of the NOR output i occurs in state t2, and the rise of the NAND output h occurs in state t4, which is temporally later than state t2, the reset flip-flop is set to "1".

When the length n of the passing object 16 in FIG. 1 is shorter than the interval k and it moves in the direction m, the timing chart in the direction l as shown in the timing chart FIG. Timing chart with the time course reversed, i.e. state t
This is a timing chart that sequentially progresses from state 4 to state t3, state t2, and state t1.

Next, the case where the length n of the passing object 16 in FIG. 1 moves in the direction l for a longer distance than the distance k will be explained using FIG. 4a. State t1 in FIG. 1 indicates a state in which the passing object 16 begins to block the light d entering the second detector 13. At this time, the detection signal e of the second detector 13 becomes "1". Further passing object 1
6 moves in the direction l, blocks the light c entering the trapezoidal prism 14 from the light source 11, and reaches a state t2 where the reflected light a begins to enter the first detector 12, and the detection signal f
becomes “1”, and the detection signal e of the second detector 13
is held as "1". When the passing object 16 further moves in the direction l and reaches a state t3 in which it does not block the light entering the trapezoidal prism 14 from the light source 11, the detection signal e of the second detector 13 and the detection signal f of the first detector 12 becomes “0”. In other words, the passing object 16 approaches the first detector 12 before passing the second detector 13 and blocks the light to the second detector 13 .

Therefore, the timing chart Figure 4a is the same as Figure 3a.
The timing chart eliminates the gap between states t2 and t3, and also eliminates the gap between states t2 and t3 in FIG. 3b in FIG. 4b, where the passing object 16 passes in the opposite direction m. This is a timing chart, and as in the case where the length n of the passing object 16 is shorter than the interval k (Fig. 3), the temporal order of the rising of the NAND output h and the NOR output i is the rising of the NOR output i when the direction is l. After that, the NAND output h rises and the set/reset flip-flop is set to "1", and in direction m, after the NAND output h rises, the NOR output i rises and the set/reset flip-flop becomes "1". 0”.

〔Effect of the invention〕

Instead of using a photo sensor having two light sources and two photodetectors, the passing direction sensor of the present invention uses one light source, a trapezoidal prism, and two photodetectors, thereby reducing the current supplied to the light source by half. This has the effect that it is not necessary to take measures such as keeping a distance between the two light sources so that the lights from the two light sources do not interfere with each other.

[Brief explanation of drawings]

Figure 1 is a top view showing one embodiment of the present invention, Figure 2 is a top view showing one embodiment of the present invention;
The figures are circuit diagrams showing detailed examples of the circuit 15 in the top view shown in Fig. 1, Fig. 3 a, b, and Fig. 4 a,
b is a timing chart for explaining one embodiment of FIG. 1, and FIG. 5 is a block diagram showing an example of a conventional passing direction detection sensor. 11...Light source, 12...First detector, 13...
...Second detector, 14...Trapezoidal prism, 15...
...Circuit for converting a detection signal into a passing direction signal, 16
...Passing object, 21...NAND circuit, 22
. . . NOR circuit, 23 . . . Set/reset flip-flop, a . Passing trajectory, c... Light entering the trapezoidal prism 14, d... Second detector 1
3, e...detection signal of the second detector 13, f...detection signal of the first detector 12, g...
Object passing direction signal, h...NAND output, i...
...NOR output, k... Distance between light a entering the first photodetector 12 and light d entering the second photodetector 13, l
...Direction of the passing object 16, m...Direction of the passing object 16 (opposite direction to l), n...Length of the passing object 16.

Claims (1)

[Claims] 1. A light source that shines light on a passing object, a first photodetector that detects the presence or absence of a passing object based on the presence or absence of reflection of the light, and a light source on the opposite side of the light source with respect to the trajectory of the object. a trapezoidal prism that is positioned and diffracts light from a light source and directs the light to an object passing through; a second photodetector that detects the presence or absence of an object passing through based on whether or not the light diffracted by the trapezoidal prism is transmitted; A passing direction detection sensor comprising a circuit that converts detection signals from a first photodetector and a second photodetector into a passing direction signal of an object.