JPH0470589A - Photosensor signal detection circuit - Google Patents

Abstract

PURPOSE:To attain low cost and small space for loading by providing a light emission control means to control in turn with time split, light emission out of the light emission parts of a multitude of photosensors and a comparator to compare the output signals sent in turn to a standard signal. CONSTITUTION:For a multitude of photosensors, a single amplifier 6 and comparator 7 are provided to flash light emitters one by one and to pick up in turn the signals from the receivers of the photosensor on flashing. In a data distributer 8, d type FF of the same numbers as the photosensors nd the like are provided to connect the output of a shift register 2 to their clock terminals. The standard voltage determined by separation voltage resistance and output voltage from the receiver of the photosensor which is input through the amplifier 6, are compared in the comparator 7. With this constitution, output pulse from an oscillator 1 is input to the shift register 2 and the driving of the photosensor receiver 4 by a driver 3 is controlled with time split. Finally, the output signal from the comparator 7 is picked up at a distributer 8 with the FF corresponding to each photosensor.

Description

TECHNICAL FIELD The present invention relates to a photosensor signal detection circuit, and more particularly to a photosensor signal detection circuit that detects output signals from a plurality of photosensors used in a medium conveyance path of a printing device.

BACKGROUND ART Conventionally, this type of photosensor signal detection circuit has been configured to have one amplifying section and one comparing section for one photosensor consisting of a light emitting section and a light receiving section.

However, the conventional photosensor signal detection circuit described above is
Since there is one detection circuit for one photosensor, in devices that use a large number of photosensors, the disadvantage is that the scale of the detection circuit becomes large, resulting in a large cost and mounting space. There is.

OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and the first objective is to provide a photosensor signal detection circuit that can reduce costs and save mounting space. be.

Structure of the Invention A photosensor signal detection circuit according to the present invention is a photosensor signal detection circuit that detects output signals from a plurality of photosensors each including a source part and a light receiving part, and which detects output signals from a plurality of photosensors including a light emitting part of the plurality of photosensors. It has a light emission control means that sends out a light emission timing signal that causes light to be emitted in a time-divisional manner, and a single comparison means that compares output signals that are sequentially sent out from the light receiving parts of the plurality of photosensors with a predetermined reference signal. , the comparison result of the comparison means output in response to the light emission timing signal is used as the detection result of the photosensor.

Example Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a photosensor signal detection circuit according to the present invention.

In the figure, a light emitting element in the photosensor light emitting section 4, 40
-1 to 40-n and the photo sensors 50-1 to 50-n in the photosensor light-receiving section 5 facing the n photosensors are the detection targets of the detection circuit according to this embodiment.

In this example, a tli-amplifying section 6 and a comparing section 7 are provided for these plurality of photosensors, and in order to eliminate the conventional system having one detection circuit for one photosensor, the photosensor light emitting section 4 is pulsed. Time-division drive control is performed using the lighting method. In other words, the light emitting parts of multiple photosensors]
The lights are made to blink one by one, and the signals from the light-receiving parts of the photosensor are sequentially picked up.

Therefore, only one of the plurality of photosensors is driven by the output of the shift register that performs a shift operation in response to the oscillation output of the oscillator (O5C) 1, and the corresponding flip-flop in the data distribution unit 8 is enabled. That is, it is sufficient to provide the same number of D-type flip-flops as the number of photosensors in the data distribution section 8, and connect the output of the shift register 2 to their clock terminals.

In the comparing section 7, a reference voltage value (slice level) determined by the voltage dividing resistor is compared with an output value of the photosensor light receiving section 5 which is manually inputted via the amplifying section 6.

In this configuration, the output pulse of the oscillator 1- is manually inputted to the shift register 2 as a shift pulse, and the driving of the photosensor light emitting unit 4 by the driver unit 3 is time-divisionally controlled. As a result, each light emitting section in the photosensor light emitting section 4 is
Blink one by one.

Then, the output signal of the photosensor light receiving section 5 during lighting is amplified to an appropriate level by the amplifying section 6, and compared with a reference voltage value by the comparing section 7. Finally, in the data distribution section 8, the output signal of the comparison section 7 is picked up by a flip-flop corresponding to each photosensor.

That is, depending on the value held in the flip-flop,
The detection result of the photosensor corresponding to that flip-flop can be determined. The oscillation frequency of the oscillator 1 may be appropriately determined depending on the transport speed of the medium transport path, the moving speed of the object to be detected, the operating speed of the comparator in the comparison section, the number of sensors, etc.

It is clear that the wooden sword method of activating each sensor in a time-sharing manner can be applied to magnetic sensors, mechanical sensors, etc. in addition to photo sensors.

As described in detail, the present invention has the effect of reducing cost and packaging space by processing a plurality of photosensor signals with a single detection circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a photosensor signal detection circuit according to an embodiment of the present invention. Explanation of symbols of main parts 1... Oscillator 2... Shift register 4... Photo sensor light emitting section 5... Photo sensor light receiving section 7...・Comparison section 8...Data distribution section

Claims (1)

[Claims] (1) A photosensor signal detection circuit that detects output signals from a plurality of photosensors including a light emitting section and a light receiving section, the circuit detecting a light emission timing signal that causes the light emitting sections of the plurality of photosensors to sequentially emit light in a time-divisional manner. and a single comparing means that compares output signals sequentially sent from the light receiving sections of the plurality of photosensors with a predetermined reference signal, and outputs the light emission in accordance with the light emission timing signal. A photosensor signal detection circuit characterized in that the comparison result of the comparison means is used as the detection result of the photosensor.