JPH0218517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal processing circuit for a light beam alarm, and more particularly to a signal processing circuit for a reflective light alarm that can determine the direction of movement.

Reflective light beam alarms that can determine the direction of movement have been well known, but as shown in Figure 1A, the light from a constant light emitting element, such as a wall, facing the detector is reflected. When a stationary object exists, there is a portion where the amount of light received by the light receiving element changes little even when the object passes due to the presence of reflected light from this stationary reflective object.

That is, FIG. 1B shows the amount of light emitted from the light emitting element reflected by an object and received by the light receiving element in relation to the distance to the object.
When a person passes a distance l ₂ from the light receiving element, there is almost no change in the amount of light received. If a person passes a distance l ₃ , the light will change in the direction of dimming, and the distance l ₄
When a person passes by, the amount of light received changes in the direction of increasing. In addition, in the case of a person passing by, the reflectance varies depending on the color and material of the clothing, and the location where the light is reflected (chest, shoulders, hands, etc.), so the distance l ₂ shown in Figure 1 B To determine the amount of light received when a person passes near the The change detection circuit detects both increasing and decreasing changes in the amount of change, and uses the detection outputs issued for each A channel and B channel to determine which channel it is. In the case of a circuit that discriminates whether the phase is fast or not, the output of the amplification circuit is as shown in FIG. In other words, an increasing direction judgment level and a decreasing direction judgment level are provided for the change in the A channel, but since the signal level for the change in the increasing direction is small, at the judgment level for the decreasing direction without exceeding a predetermined level, the predetermined level is set. It's starting to surpass the level. However, in the B channel, the signal in the increasing direction also exceeds a predetermined level, so when comparing channels A and B, the phase of the B channel may be faster, and the signal in the opposite direction may be compared. Sometimes I ended up outputting it.

The present invention is aimed at improving the above-mentioned drawbacks, and the invention amplifies the outputs of two light receiving elements separately, and the output of the amplification circuit is divided into increases and decreases from the steady state. Each of them is made to output a signal when it exceeds a predetermined level, and the direction of movement is determined by determining the phase difference between the increase and decrease.

The present invention will be explained in detail below based on one embodiment thereof.

In FIGS. 5 and 6, 1 is a change detection circuit for the A channel, 2 is a change detection circuit for the B channel, and 1A is an increase detection circuit that detects the level of the increase change. 1B is a decrease detection circuit that detects the level of change in decrease. The same applies to 2A and 2B. Reference numeral 3 denotes a phase detection circuit, which includes an incremental phase difference discriminating circuit 3A for determining the phase of the incremental detecting circuits 1A and 2A of the change detecting circuits 1 and 2;
The phase difference detection circuit 1B includes a phase difference detection circuit 3B for determining the phase of the phase difference detection circuit 1B and phase difference detection circuit 3B. The outputs α and β of the phase difference determination circuit 3 form a direction determination signal. A specific example of the electric circuit shown in FIG. 5 is shown in FIG. In FIG. 6, reference numeral 4 denotes an amplification circuit; the A channel amplification circuit is 4A, and the B channel amplification circuit 4B, each using an operational amplifier. The change detection circuit consists of a comparator, and the reference voltage is the power supply voltage Vcc, which is connected to the resistors Ra, Rb,
Dividing the pressure by Rc and Rd, the judgment level for the increase in the change is V ₁ and the judgment level for the decrease in the change is V ₂
Then, V ₁ = [(Rb+Rc+Rd)/(Ra+Rb+Rc+
Rd)]・Vcc V ₂ = [Rd/(Ra+Rb+Rc+Rd)]・Vcc. Next, in the embodiment shown in FIG. 6, since the phase difference circuit includes diodes D ₁ to D ₄ , the phase difference discrimination circuit will not produce an output unless both channels A and B have outputs. Fig. 7 shows an electrical waveform diagram, and Fig. 7 shows the change signals of the A and B channels, and Fig. 7 shows the output Ap of the signal of the increase judgment level V ₁ or higher among the change signals of the A channel. Figure 7 shows the output Bp of the signal whose increase judgment level is V _{1 or} above among the change signals of the B channel and the output Aq of the signal whose decrease judgment level is V ₂ or less. Indicates the signal output Bq. Figure 7 shows the α and β outputs of the phase difference discrimination circuit. The range of FIG. 7 shows a case where an object moves from the A channel side to the B channel side in the detection area, and the range of FIG. 7 shows a case where an object moves from the B channel side to the A channel side. The area in Figure 7 shows the case where an erroneous signal enters the A channel, and Figure 7 shows the case where the object moves from the A channel side to the B channel side, but the change in the A channel signal is determined by the increase in the signal. This shows cases where the level was not reached.
In other words, in the case of Fig. 7, the change signal is captured normally, but the increase and decrease of the change signals of both channels A and B exceed the judgment level. When the outputs of the phase difference discriminating circuit overlap, the output α or β of the phase difference discriminating circuit is output. Even in the case where the increase in the change signal of the A channel does not reach the discrimination level as shown in the area of FIG. 7, the context is determined based on the decrease and the α signal is output.

Note that in FIG. 7, the α or β outputs are each output twice, but the first α or β signal is used to drive the notification means that has determined the direction.

As described above, according to the present invention, there is one light projecting element that projects modulated light, two light receiving elements that receive reflected light reflected by passing an object, and light receiving signals of these two light receiving elements. In a light beam alarm device that includes a signal processing circuit that detects which of the light receiving elements receives light quickly and determines the direction of movement, the signal processing circuit is replaced with an amplifying circuit that amplifies the light reception signal of each light receiving element. A change detection circuit that divides the output of the amplification circuit into an increase region and a decrease region and outputs both increase and decrease signals when the output exceeds a predetermined level, The signal processing circuit of the light beam alarm is constructed from a phase discrimination circuit that separates the increase and decrease of the change detection circuit and distinguishes the phase between the increases and decreases, so the detection area In addition to being able to determine the direction of movement of an object in
As shown in the figure, the level of the change signal is small,
Even in cases where the discrimination level is not exceeded, the phase can be reliably detected by the phase difference discriminating circuit for the reduced phase difference. Even in such cases, it is possible to identify the direction of movement. Therefore, it is possible to output extremely reliable signals.

[Brief explanation of drawings]

FIG. 1A to FIG. 4 show a conventional example of the present invention, and FIG. 1 is a schematic diagram showing the state of use. Figures 2 and 3 show the block diagrams, and Figure 4 shows the block diagrams.
The figure shows an electrical signal waveform diagram. 5 to 7 are drawings showing one embodiment of the present invention, in which FIG. 6 is a block diagram and FIG. 6 is an electric circuit diagram. 7th
The figure shows an electrical waveform diagram. 1... A channel change detection circuit, 2...
B channel change detection circuit, 3... phase difference discrimination circuit, 4... amplification circuit.

Claims (1)

[Claims] 1. One light emitting element that emits modulated light, two light receiving elements that receive reflected light that is reflected by passing an object, and which one of the light receiving elements of these two light receiving elements responds quickly. In a light beam alarm device that includes a signal processing circuit that detects whether light is received and determines the direction of movement, the signal processing circuit is combined with an amplification circuit that amplifies the light reception signal of each light receiving element and the output of this amplification circuit. a change detecting circuit that divides the signal into an increasing region and a decreasing region and outputs both increasing and decreasing signals when it exceeds a predetermined level; and an increasing amount of the respective change detecting circuits corresponding to the two light receiving elements; 1. A signal processing circuit for a light beam alarm, comprising a phase discrimination circuit that separates the decrease and determines the phase between the increases and between the decreases.