JPH0450791A - Photosensor circuit - Google Patents

Abstract

PURPOSE:To decrease the number of sensor signal processing circuits by putting one of optical sensors in operation and processing its signal by one sensor signal processing circuit. CONSTITUTION:A control circuit 1 turns on one transistor TR1 among (n) TRs (n: optional natural number) in a light emitting element turning-on circuit 9 and only one light emitting element PD1 in a light emitting element group 2 illuminates. Consequently, the current generated by one photodetecting element PT1 in a photodetecting element group 3 passes through one diode D1 in a diode group 4 to generate a voltage across a photocurrent detection resistance 5. The voltage is amplified 6 and converted by a voltage comparator 7 into a detection signal indicating whether or not a medium is present and the signal is inputted to one D-FF1 in the D-FF group 8 and latched with the hold signal of the circuit 1. This operation is performed in order as to all the elements PD1 - PDn and then information on the presence/absence state of the medium by all sensors is latched in the D-FF group 8, so the number of sensor signal processing circuits can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical sensor circuit that detects a medium using an optical sensor that combines a light emitting element and a light receiving element.

[Conventional technology]

In a conventional optical sensor circuit that detects a medium using an optical sensor that combines a light-emitting element and a light-receiving element, each string of optical sensors includes one photocurrent detection resistor, one voltage amplifier, and one A method using a set of sensor signal processing circuits having a voltage comparator is adopted.

[Problem to be solved by the invention]

The conventional optical sensor circuit as described above has a drawback in that as the number of optical sensors increases, the number of sensor signal processing circuits increases accordingly.

[Means for Solving the Problems] The optical sensor circuit of the present invention includes n optical sensors that are a combination of n light emitting elements and n light receiving elements corresponding thereto, n diodes, and one optical sensor. a photocurrent detection resistor of 1
It has one set of sensor signal processing circuits having n voltage amplifiers and one voltage comparator, n D-type flip-flops, one control circuit, and one light emitting element lighting circuit. There is.

That is, the optical sensor circuit of the present invention is an optical sensor circuit that detects a medium using an optical sensor that is a combination of a light emitting element and a light receiving element. n photosensors in which n light receiving elements are combined, n diodes coupled to the n light receiving elements, and 1 through which the output current of the n diodes flows.
one photocurrent detection resistor, one voltage amplifier that amplifies the voltage of the photocurrent detection resistor, and one voltage comparator that inputs the output signal of the voltage amplifier to detect the presence or absence of a medium;
n Ds that input and hold the output signal of the voltage comparator.
type flip-flop, and any one of the light emitting elements.
A light emitting element lighting circuit that lights up the n light emitting elements, and n D-type flip-flops that hold the output signal of the voltage comparator, and a control circuit operates the light emitting element lighting circuit to At the same time as lighting up any one light emitting element among the light emitting elements, one D corresponding to it lights up.
The type flip-flop is operated to hold the output signal from the voltage comparator.
a light-emitting element group having n light-emitting elements; a light-receiving element group having n light-receiving elements corresponding to each of the n light-emitting elements; a diode group having a diode, one photocurrent detection resistor through which the output current of the n diodes flows, one voltage amplifier that amplifies the voltage of the photocurrent detection resistor, and an output signal of the voltage amplifier. a voltage comparator that inputs and detects the presence or absence of a medium; n D-type flip-flops that input and hold output signals of the voltage comparators;
A light emitting element lighting circuit having n driving units corresponding to each of the n light emitting elements, and operating any one driving unit in the light emitting element lighting circuit, and operating the n D
and one control circuit that drives the holding operation of one D-type flip-flop corresponding to the one driving section in the D-type flip-flop.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In FIG. 1, the control circuit 1 includes a light-emitting element lighting circuit 9 having n transistors (n is any natural number and is the same number as the number of light-emitting elements in the light-emitting element group 2 and the number of light-receiving elements in the light-receiving element group 8). Turn on one of the transistors TR,
One light emitting element (light emitting diode) in light emitting element group 2
Only P D t lights up. As a result, one light receiving element (phototransistor) PT in the light receiving element group 3,
A current is generated. This current flows into the photocurrent detection resistor 5 through one diode Di in the diode group 4 and generates a voltage V1. This voltage V1 is amplified by a voltage amplifier 6 and further converted by a voltage comparator 7 into a detection signal for detecting the presence or absence of a medium. This detection signal is input to one D-type flip-flop FF□ in the D-type flip-flop group 8, and is latched there by a hold signal output from the control circuit 1.

This operation is performed by the light emitting elements P D 2 of the light emitting element group 2.
By sequentially performing from PD to PD, information regarding the presence or absence of a medium from all optical sensors is latched into the D-type flip-flop group 8.

〔Effect of the invention〕

As explained above, the optical sensor circuit of the present invention combines n sets of optical sensors and n diodes, operates one set of optical sensors among the n optical sensors, and converts the signal into one signal. By enabling processing by a set of sensor signal processing circuits, there is an effect that the number of sensor signal processing circuits can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Control circuit, 2... Light emitting element group, 3... Light receiving element group, 4... Diode group, 5... Photocurrent detection resistor, 6... Voltage amplifier, 7... Voltage comparator, 8...
- D-type flip-flop group, 9... light emitting element lighting circuit.

Claims (1)

[Scope of Claims] 1. In an optical sensor circuit that detects a medium using a photosensor that is a combination of a light emitting element and a light receiving element, n light emitting elements (n is any natural number) and n light receiving elements corresponding thereto; n optical sensors combining elements, n diodes coupled to the n light receiving elements, one photocurrent detection resistor through which the output current of the n diodes flows, and the photocurrent detection resistor. one voltage amplifier that amplifies the voltage of the voltage amplifier, one voltage comparator that inputs the output signal of the voltage amplifier to detect the presence or absence of a medium, and one voltage comparator that inputs and holds the output signal of the voltage comparator. n D-type flip-flops, a light emitting element lighting circuit for lighting any one of the light emitting elements, and n for holding an output signal of the voltage comparator.
A control circuit operates the light emitting element lighting circuit to light up any one light emitting element among the n light emitting elements, and at the same time, a corresponding one D flip-flop is provided. An optical sensor circuit characterized in that the output signal from the voltage comparator is held by operating a type flip-flop. 2. Input the output signals of a light emitting element group having n light emitting elements, a light receiving element group having n light receiving elements corresponding to each of the n light emitting elements, and each of the n light receiving elements. a diode group having n diodes, one photocurrent detection resistor through which the output current of the n diodes flows, one voltage amplifier that amplifies the voltage of the photocurrent detection resistor, and the voltage amplifier a voltage comparator that inputs the output signal of the voltage comparator to detect the presence or absence of a medium, n D-type flip-flops that input and hold the output signal of the voltage comparator, and corresponds to each of the n light emitting elements. a light-emitting element lighting circuit having n driving units, and operating any one driving unit in the light-emitting element lighting circuit;
and one control circuit that drives a holding operation of one D-type flip-flop corresponding to the one driving section among the D-type flip-flops.