JPH06300857A - Optical sensor device - Google Patents

Abstract

PURPOSE:To discriminate approaching of an object by allowing light from a light emitting part to be reflected from the object and then to enter a light reception part. CONSTITUTION:In an object sensor circuit for detecting approaching of an object 3 by reflection of a light pulse from a light emission part 2 in synchronization with an oscillation circuit 1 by the object 3 and then its incidence to a light reception part 4, an AND circuit 5 for outputting incidence signal in synchronization with the light emitting part 2 is compared with a NAND circuit 10 for outputting incidence signal when the incidence signal is not in synchronization with the light emitting part 2, thus preventing a detection output signal from being output when disturbance light which enters while the light emitting part 2 does not emit light enters and hence reducing erroneous detection for external disturbance light and achieving a more secure title device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sensor device for approaching and passing an object in an optical sensor, and in particular, it detects externally received ambient light by detecting light received during a period in which no light is emitted, The present invention relates to an optical sensor device capable of preventing erroneous detection.

[0002]

2. Description of the Related Art The prior art is disclosed in JP-A-54-93474.
As described in Japanese Patent Laid-Open Publication No. 2003-242242, malfunction cannot be avoided for disturbance light having a high frequency.

[0003]

The above-mentioned prior art is intended to detect the approach of an object by receiving the reflected light synchronized with the light emitting section, but the pulse-like pattern can be obtained without synchronizing with the light emitting section. No consideration has been given to malfunctions when disturbance light is incident, particularly when high frequency pulsed light such as an inverter type fluorescent lamp is incident.

[0004]

According to the present invention, in order to avoid the above-mentioned malfunction with respect to ambient light, the light emitting section is made to emit light intermittently, and the light receiving section and its detection circuit are synchronized with the intermittent light emitting period for detection. And a circuit for invalidating the detection operation by receiving light during a period not synchronized with the intermittent light emission period.

[0005]

In the approach detection of the object, the malfunction due to the ambient light is eliminated, and the detection method with high accuracy can be realized.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an optical sensor device according to the present invention, in which 1 is an oscillation circuit, 2 is a light emitting section, 3 is an approaching object to be detected, and 4 is a light receiving section. 5 is an AND circuit, 6 is a diode, 7 is a resistor, 8
Is a capacitor, 9 is an inverter (inverting circuit), 10 is N
AND circuit, 11 is a diode, 12 is a resistor, and 13 is a detection output signal.

In FIG. 1, the light emitting section 2 emits pulsed light in synchronization with the pulse output from the oscillator circuit 1. The emitted light is reflected by the approaching object 3 and enters the light receiving section 4. The light input signal from the light receiving unit 4 is input to the AND circuit 5, and at the same time, the output signal from the oscillation circuit 1 is also input. Therefore, the output of the AND circuit 5 is synchronized with the light emitting unit 2 and the light receiving unit 4
"H" is output only for the light incident signal of. The output of the AND circuit 5 is rectified by the diode 6 and further charged and smoothed by the integrating circuit including the resistor 7 and the capacitor 8. When the voltage of the detection output 13, which is the smoothed signal, reaches a predetermined voltage, it is detected as the approach of the object 3.

Here, similarly, the light incident signal from the light receiving portion 4 is also input to the NAND circuit 10, and at the same time, the output signal from the oscillation circuit 1 is also input via the inverting circuit 9. Therefore, the output of the NAND circuit 10 is always "H", and is output "L" only when the ambient light enters the light receiving unit 4 while the light emitting unit 2 is not emitting light. Of the NAND circuit 10
The L ″ output discharges the electric charge charged in the capacitor 8 via the diode 11 and the resistor 12. As a result, the AND circuit 5 and the NAND circuit 10 output the ambient light that always enters. As a result, the capacitor 8 is repeatedly charged and discharged, and thus the voltage does not reach a predetermined voltage, so that erroneous detection is not performed.

FIG. 2 is a timing chart of the object approach detection according to the above embodiment. 1 is an oscillation circuit output pulse, 2 is a light emitting unit output pulse, 3 is a light receiving unit light input signal, 4
Is an AND circuit output waveform, 5 is a NAND circuit output waveform, 6
Indicates a detection output waveform, and 7 indicates a detection voltage.

Now, in synchronization with the output pulse 1 of the oscillation circuit, the light emitting section repeats light emission and extinction like the light emitting section output pulse 2. Here, when the light from the light emitting unit is reflected by the object due to the approach of the object and enters the light receiving unit, the light receiving unit light incident signal 3 is output as shown in the figure. Here, the output waveform 4 of the AND circuit, which receives the oscillation circuit output pulse 1 and the light receiving portion light incident signal 3, is output as shown in the figure. Further, the output waveform 5 of the NAND circuit which receives the inverted signal of the oscillation circuit output pulse 1 and the light receiving portion light incident signal 3 is always "H". At this time, the output waveform 5 of the NAND circuit that performs the discharging operation is always "H", and is ignored for the detection output. In other words, the detection output is charged only by the light receiving section light incident signal 3 and is output as the detection output waveform 6. When this output exceeds a predetermined detection voltage 7, it is determined that the object approach is detected.

FIG. 3 is a timing chart for the disturbance light of the above embodiment. As in the case of FIG. 2, the light emitting section repeats light emission and extinction like the light emitting section output pulse 2 in synchronization with the output pulse 1 of the oscillation circuit. Here, the light-receiving portion light-receiving signal 3 is always output as a light-receiving state by the ambient light, as shown in the figure. Therefore, the output waveform 4 of the AND circuit is output as shown in the figure, and the output waveform 5 of the NAND circuit is similarly output as shown in the figure.

At this time, the detection output waveform 6 is charged by "H" of the output waveform 4 of the AND circuit and discharged by "L" of the output waveform 5 of the NAND circuit, so charging and discharging are repeated. As a result, the detection voltage 7 will not be exceeded and no detection will be performed.

Here, by emitting light with a high-frequency carrier during the period when the light-emitting portion is emitting light and selectively receiving light with the carrier frequency in the light-receiving circuit of the light-receiving portion, it is more advantageous for disturbance light. Needless to say. Further, it goes without saying that the oscillation circuit output pulse and the light-receiving portion light-receiving signal can be input to the microprocessor to have the same effect as that of the above embodiment in terms of software. Needless to say, the same effect can be obtained by further incorporating the oscillation circuit into the microprocessor and outputting the oscillation circuit output pulse from the microprocessor.

[0015]

As described above, according to the present invention,
A more reliable optical sensor device can be obtained by reducing erroneous detection with respect to ambient light from the outside.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an optical sensor device according to the present invention.

FIG. 2 is a timing chart of an object detection timing according to the embodiment of the present invention.

FIG. 3 is a timing chart of disturbance light incidence according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Oscillation circuit, 2 ... Light emitting part, 3 ... Object, 4 ... Light receiving part, 5
... AND circuit, 6 ... Diode, 7 ... Resistor, 8 ... Capacitor, 9 ... Inverter (inverting circuit), 10 ... NAND
Circuit, 11 ... Diode, 12 ... Resistor, 13 ... Detection output signal.

Claims (1)

[Claims] 1. A means for detecting an approach of an object, comprising: a light emitting section which is a light source; and a light receiving section for detecting light, wherein light from the light emitting section is reflected by an object and enters the light receiving section, or An optical sensor device having means for detecting that an object is approaching or passing due to light being cut off by crossing in front of the light receiving part or the light emitting part when the object approaches or passes in the state of being constantly reflected by the reflector. At
Equipped with means for intermittently emitting light from the light emitting portion and means for receiving light in synchronism with the light emission, capable of performing light emission intermittently and determining light other than the light emitting portion when receiving light during a period of no light emission. An optical sensor device.