JPH0256767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a light projector that projects modulated light and a light receiver that receives the light projected from the projector, and the light projected from the projector is blocked by passing through an object. Alternatively, the present invention relates to an optical relay that detects the passage of an object by detecting a change in the light reception signal of the light receiver due to reflection.

Conventionally, as shown in FIG. 1, a device is known in which light B projected from a single light projecting element A is reflected by an object C, and this reflected light D is received by a light receiver E to detect the passage of the object. However, there was a risk of malfunctions caused by flying insects, for example, or by power supply noise. Conventionally, when particularly high reliability is required, two light beams are emitted from two light projecting elements F ₁ and F ₂ as shown in Figure 2.
B ₁ and B ₂ are projected and the light D ₁ and D ₂ reflected by object C
It is conceivable to receive the light with one light-receiving element E and output an output signal when there are these two light-receiving signals, but providing two light-emitting elements means that two reflecting mirrors and Since it requires two light emitting elements and two light emitting element drive circuits, it is not preferable in terms of cost.

The present invention aims to improve the above-mentioned drawbacks, and includes a projector that projects two luminous fluxes by attaching one light emitting element to the center of the focal point of a reflecting mirror having two focal points; An optical relay is constituted by a light receiver that receives a reflection of the two light beams projected from the light projector or a light blocking signal and outputs an output signal when there is a change in both of the two light beams.

The present invention will be explained in detail below according to its embodiments.

In FIG. 3, reference numeral 1 is a reflecting mirror having two focal points. 2 is a light emitting element. 3 is a printed board. The reflecting mirror 1 is symmetrical with respect to the center line a-a', as shown in FIG. It is obtained by dividing the parts into equal parts and rotating them outward by an angle θ around point O, and then combining them, and the focal points f ₁ and f ₂ are connected to the center line (a-a').
Get on both sides. Reflector 1 with these two focal points
does not necessarily have to be constructed by dividing the semi-parabolic reflector described above into two equal parts; for example, as shown in Fig. 5A, it is possible to combine the divided pieces 1c and 1c' of the cylinder 1b. It may be of the form shown in FIG. 5B.

One light emitting element 2 is located at the center of two focal points f ₁ and f ₂ . This light emitting element 2 is driven by a light projecting circuit 5, for example, a circuit as shown in FIG. That is, the light emitting circuit 4 is connected in series to the transistor Tr ₁ controlled by the oscillation circuit 4.
Emits modulated light that repeatedly flashes at a cycle of . The above reflecting mirror 1, light emitting element 2, and light projecting circuit 3 constitute a projector P. In the case of the embodiments shown in FIGS. 5A and 5B, the light emitting element 2 is preferably a linear light source rather than a point light source. The light receiver Q is composed of a reflecting mirror 1, one light receiving element 6, and a signal processing circuit 7. Signal processing circuit 7
includes an amplification circuit 8 for amplifying the output of the light receiving element 6, a detection and waveform shaping circuit 9, and a two-pulse determination circuit 1.
0 and an output circuit 11. Note that the two-pulse determination circuit 10 is, for example, a circuit as shown in FIG. That is, a delay circuit (delay time t ₁ ), a differentiation circuit 10a, a timer circuit for setting the lower limit time T ₂ (timer output time t ₂ ), a timer circuit for setting the upper limit time.
T ₃ (timer output time t ₃ ) and AND gate 10
It consists of b.

The light emitting element 2 emits modulated light by the light emitting circuit 5, but the reflecting mirror 1 focuses two focal points f,
f and the light emitting element 2 is located at the center Z point, as shown in Fig. 4, the light travels from ZO→ and is reflected to Oα→ and Oβ→, and the light from ZM→ is reflected from Mγ→ The light of ZN→ is reflected in the direction of N ₆ →, and the light of K ₁ ,
It is projected with two luminous fluxes of K ₂ . When an object passes across these projected light beams K ₁ and K ₂ , if the light receiver Q is formed as a reflective optical relay as shown in FIG. 3, the reflected light R ₁ ,
R ₂ is received by the light receiving element 6 via the reflecting mirror 1 of the light receiver Q. Since there is a distance L between the light beams K ₁ and K ₂ , this reflected light is received with a time interval T (see FIG. 8) depending on the speed of the passing object. In the case of human body detection, this time interval T is approximately T≒[40×10 ^-2 /4×10 ³ ]・3.6×10 ³ seconds, assuming that L = 40 cm and the walking speed of a human being is 4 km/hour.
T≒0.36 seconds. When this optical relay is used as a human body detector, the timer circuit of the two-pulse judgment circuit 10, for example, T≒0.05 seconds (time corresponding to the speed at which a person runs) to 0.1 seconds (time corresponding to the time at which a person walks slowly). ). Therefore, as shown in FIG. 81, two pulses R ₁ and R ₂
If it occurs at a time of 0.05 seconds < T < 0.1 seconds, the output (see Figure 8) will occur, and if a single pulse is input as shown in Figure 8, or two pulses as shown in Figure 8. If t is an interval shorter than ₁ , there is no output if input.

Although an example is shown in which the same reflecting mirror as the projector P is used as the light receiver Q, the present invention is not limited to this.

As described above, according to the present invention, one light emitting element 2 is attached to the center of both focal points of the reflecting mirror 1 having two focal points, and two luminous fluxes are projected from one light emitting element 2. A change in the light receiving signal received by one light receiving element 6 of the two light beams reflected or blocked by the light projector P passing through an object is detected, and when the light receiving signals of the two light beams both change, The light receiver Q, which outputs an output, is installed on both sides of a single printed circuit board 3 so that the light emitting direction of the light emitter P and the incident direction of the light beam received by the light receiver Q are the same direction as an optical relay. If a small object such as an insect were to fly in, the possibility that the two light beams K ₁ and K ₂ would cross each other due to the flight direction and size is extremely small, and malfunctions caused by flying beetles are almost eliminated. In addition, if there is noise from the power supply, the timer setting time T of the two-pulse judgment circuit
The pulses arrive at longer intervals, and no output is produced. Moreover, the emitter and receiver can be placed above and below the printed circuit board, so that only one reflector for the emitter, one reflector for the receiver, one light emitting element, and one light receiver are required.
The dimensions are smaller and the price is lower, resulting in a desirable optical relay.

[Brief explanation of drawings]

1 to 2 are schematic diagrams showing a conventional example of the present invention, and FIG. 3 to 8 are drawings for explaining the present invention, in which FIG. 3 is a partial perspective view, and FIG. 4 is a reflecting mirror. 3 (x-x') sectional view of 1, FIG. The block diagram and FIG. 8 show waveform diagrams of each part. P... Emitter, Q... Receiver, 1... Reflector,
2... Light emitting element, 5... Light emitting circuit, 6... Light receiving element, 7... Signal processing circuit, 10... 2 pulse determination circuit.

Claims (1)

[Claims] 1 One light emitting element is attached to the center of both focal points of a reflecting mirror having two focal points, and two light emitting elements are
A projector that emits two beams of light, detects changes in received light signals of the two beams that are reflected or blocked by passing an object, and outputs an output when both of the received signals of the two beams change. An optical relay characterized in that a light receiver and a light receiver are mounted on both sides of one printed circuit board so that the light emitting direction of the light emitter and the incident direction of the light beam received by the light receiver are the same direction.