JPH066198A - Output adjustment circuit for photo interrupter - Google Patents

Abstract

PURPOSE:To adjust an output of a photo interrupter with simple configuration. CONSTITUTION:A switch SW1 between a pulse generator 24 and an LED 28 is set to be closed to let the LED 28 be in light emitting state continuously. A variable resistor VR is adjusted as measuring a voltage based on the continuously emitted light rays detected by a photo transistor(TR) 30 by a measurement device connecting to a check terminal 34. Thus, the output level is set to a desired level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photointerrupter output adjusting circuit capable of easily adjusting the output of a photointerrupter composed of a light emitting element emitting pulsed light and a light receiving element.

[0002]

2. Description of the Related Art In a sheet conveying apparatus, a photo interrupter is used to detect the presence or absence of the sheet in a non-contact state by using a light emitting element and a light receiving element.

By the way, when the sheet body is a photosensitive material, there arises a problem that the photosensitive material is exposed to light emitted from a light emitting element. In this case, it is known from the characteristics of the light-sensitive material that light emission can be avoided by causing the light-emitting element to emit light in a pulse in a sufficiently short time.

On the other hand, the light emitting element and the light receiving element constituting such a photo interrupter usually have individual variations in sensitivity characteristics. Therefore, it is necessary to adjust the output of the light receiving element after installing them in the device. The variation in the output also occurs due to the deviation of the optical axes of the light emitting element and the light receiving element and the distance between the light emitting element and the light receiving element.

Therefore, in order to adjust the variations in these outputs, conventionally, a resistance element for converting I / V of a photocurrent obtained from a light receiving element is a variable resistance, and the output level is adjusted by adjusting the variable resistance. I was going.

[0006]

However, as described above, when the object to be detected is a photosensitive material, since the light emitting element is made to emit light in pulses, it is easy to perform voltage measurement at the connection point of the variable resistance element. However, there is the inconvenience that a large digital voltmeter, a tester or the like cannot be used and a large measuring instrument such as an oscilloscope must be used.

Therefore, the present invention has been made in order to overcome the above-mentioned inconvenience, and provides a simple measuring device such as a tester by providing an extremely simple switching circuit capable of continuously emitting light from a light emitting element. It is an object of the present invention to provide an output adjustment circuit of a photo interrupter which can detect the output level of a light receiving element and adjust the output level.

Further, according to the present invention, there is provided a switching circuit for switching the threshold value in the determination means for determining the presence or absence of the measurement object inserted between the light emitting element and the light receiving element, and the output of the determination means after the threshold value is switched. An object of the present invention is to provide an output adjustment circuit for a photo interrupter, which can easily adjust the output level without using a measuring instrument.

[0009]

In order to achieve the above-mentioned object, the present invention provides a light emitting element that emits pulsed light according to a pulse signal output from a pulse generator, and receives the pulsed light to generate an electrical signal. An output adjusting circuit in a photointerrupter composed of a light receiving element for conversion, which is connected to the pulse generator, uses the pulse signal as a continuous signal, and makes the light emitting element continuously emit light, and emits light. Level adjusting means connected to the element and adjusting the level of the electric signal, and connected to the light receiving element,
A level detection terminal for detecting the level of the electric signal.

Further, according to the present invention, an output in a photo interrupter comprising a light emitting element which emits a pulse light by a pulse signal output from a pulse generator and a light receiving element which receives the pulsed light and converts it into an electric signal. An adjustment circuit, which is connected to the light receiving element and which adjusts the level of the electric signal, and the electric signal is compared with a predetermined threshold value to determine the presence or absence of a detection target between the light emitting element and the light receiving element. Connected to the input side of the determination means, threshold switching means for switching the level of the threshold to a desired level when there is no detection target, and connected to the output side of the determination means,
And a discrimination signal detecting means for detecting a discrimination signal indicating the presence or absence of a detection target from the discrimination means for setting the threshold to a desired level by the threshold switching means.

Further, according to the present invention, the output of the photo interrupter is composed of a light emitting element which emits pulsed light by a pulse signal output from a pulse generator, and a light receiving element which receives the pulsed light and converts it into an electric signal. An adjusting circuit, which is connected to the light receiving element, adjusts the level of the electric signal, and compares the electric signal with a predetermined threshold value to determine the presence or absence of a detection target between the light emitting element and the light receiving element. Connected to the discriminating means for switching the threshold level to a level at which there is no detection target, and a discriminator connected to the output side of the discriminating means for detecting a discriminating signal indicating the presence or absence of the detection target from the discriminating means. And a signal detecting means.

[0012]

In the output adjusting circuit of the photo interrupter according to the present invention, the pulse signal output from the pulse generator is switched to a continuous signal and supplied to the light emitting element to continuously emit light from the light emitting element, and the continuous light is emitted. Light is received by the light receiving element and the output level is detected by a measuring device such as a tester. Then, the output level on the light receiving element side is adjusted so that the detected value becomes a desired value.

Further, in the output adjusting circuit of the photo interrupter according to the present invention, the light from the light emitting element emitting pulsed light is received by the light receiving element, and the obtained output signal is set to a level such that there is no detection target in the discriminating means. The output is detected by the discrimination signal detecting means. Then, the discrimination signal detecting means adjusts the output signal to a level at which the signal changes from no detection target to detection target.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A photo interrupter output adjusting circuit according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 shows a schematic structure of an image recording apparatus 10 to which the output adjusting circuit of the photo interrupter according to the present invention is applied. The image recording apparatus 10 is an unexposed film F.
A film magazine 12 for supplying the film F, an exposure drum 14 for recording image information on the film F, transfer rollers 16a to 16c for transferring the film F, and a cutter 18 for cutting the film F into predetermined lengths. Basically consists of Then, between the film magazine 12 and the exposure drum 14, the exposure drum 14 and the transport roller 1
Photointerrupters 20a to 20d each including an LED, which is a light emitting element that emits pulsed light, and a phototransistor, which is a light receiving element, are disposed in each of the conveyance paths 6a and between the cutter 18 and the conveyance roller 16c.

The photo interrupter 20a detects the presence / absence of the film F between the film magazine 12 and the exposure drum 14 to confirm the presence / absence of a photosensitive material in the film magazine 12. The photo interrupter 20b detects that the film F has passed through the exposure drum 14. The photo interrupter 20c detects the leading end of the film F, and also detects the cutting by the cutter 18. The photo interrupter 20d detects the front end or the rear end of the film F.

Here, the film F is characterized in that it is not exposed to light from the LED for a sufficiently short time. Therefore, the presence or absence of the film F can be detected without exposing the film F by making the LED emit light in pulses at sufficiently short time intervals.

FIG. 1 shows the photo interrupter 20 shown in FIG.
The 1st Example of the control circuit 22 of a is shown. In this case, the control circuits of the other photo interrupters 20b to 20d have the same configuration, and thus the description thereof will be omitted.

The control circuit 22 outputs the output terminals CK1 and CK2 based on the control signal supplied from the CPU to the input terminal A.
Each has a pulse generator 24 for outputting a pulse signal. At the output terminal CK1 of the pulse generator 24, an L which constitutes a photo interrupter 20a via a driver 26 is provided.
The ED 28 is connected. The anode side terminal of the LED 28 is connected to the power supply V _CC , and the cathode side terminal is grounded via the switch SW1 as the light emission state switching means.

A phototransistor 30, which is a light-receiving element forming the photointerrupter 20a, is arranged opposite to the LED 28. The collector terminal of the phototransistor 30 is connected to the power supply V _CC , and the emitter terminal is grounded via the variable resistor VR as the level adjusting means and is also connected to the amplifier 32. A check terminal 34, which is a level detection terminal for detecting the voltage level at the input terminal, is provided at the input terminal of the amplifier 32. The output terminal of the amplifier 32 is connected to the-terminal of the comparator 36, which is the discrimination means. The + terminal of the comparator 36 is connected to the connection point of the voltage dividing resistors R3 and R4 for dividing the power supply V _CC .

On the other hand, the output terminal CK2 of the pulse generator 24
Is connected to the clock terminal CK of the latch circuit 38. The data input terminal of the latch circuit 38 is connected to the output terminal of the comparator 36, and the signal from the output terminal of the latch circuit 38 is supplied to the CPU via the driver 40.

Next, the control circuit 2 configured as described above.
A method of adjusting the output of the photo interrupter 20a using 2 will be described.

The pulse generator 24 outputs a pulse signal from the output terminal CK1 based on the control signal from the CPU supplied to the input terminal A, thereby causing the LED 28 to emit light in pulses. Therefore, the switch SW1 is closed (O
N), the LED 28 is in a state of continuously emitting light by the current supplied from the power source V _CC . On the other hand, film F
In the absence of light, the phototransistor 30 receives the continuous emission light and converts it into an electric signal. This electric signal is converted from current to voltage by the variable resistor VR connected to the emitter terminal of the phototransistor 30 and supplied to the amplifier 32.

Here, the operator connects a digital voltmeter or a tester to the check terminal 34, and the amplifier 32
Measure the voltage value at the input terminal of. In this case, LE
Since D28 emits light continuously, the voltage value is measured as an effective value. Therefore, if the variable resistor VR is adjusted by a driver or the like, the voltage value at the check terminal 34 can be adjusted to a desired level at which it can be determined that there is no film F.

Next, the operation when the presence or absence of the film F is detected by the photo interrupter 20a adjusted as described above will be described.

When there is no film F between the LED 28 and the phototransistor 30, the pulsed light emitted from the LED 28 is converted into a current signal by the phototransistor 30, and the current signal is adjusted by the variable resistor VR.
Is supplied to the amplifier 32 as a voltage signal. The amplifier 32 amplifies the voltage signal, and the comparator 36
Supply to the terminal. The comparator 36 compares the threshold value obtained by dividing the power source V _CC by the voltage dividing resistors R3 and R4 with the voltage value supplied from the amplifier 32. In this case, the signal supplied to the data input terminal of the latch circuit 38 remains 0, and therefore its output terminal also remains 0, so that C
The PU will detect the state where the film F is not present.

On the other hand, when the film F passes between the LED 28 and the phototransistor 30, since the pulsed light emitted from the LED 28 is blocked by the film F, the output of the amplifier 32 is close to 0 V, and therefore the output of the comparator 36. Is in the 1 state. In this case, the latch circuit 38 latches the data at the data input terminal based on the pulse signal from the output terminal CK2 of the pulse generator 24 and outputs it to the CPU. As a result, the CPU detects that the film F is present.

In order to avoid the exposure of the film F, the CPU outputs a control signal for stopping the pulse emission of the LED 28 until the next detection to the pulse generator 24 after detecting the film F.

FIG. 3 shows a second embodiment of the output adjusting circuit of the photo interrupter according to the present invention. The same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this case, the input terminal A of the pulse generator 24 constituting the control circuit 41 is grounded via the diode D1 and the switch SW2-1. The diode D
The power source V _CC is connected to the cathode terminal of 1. Further, a voltage dividing resistor R5 as a threshold value switching means and a switch SW2-2 are connected to a connection point of the voltage dividing resistors R3 and R4 that determine the threshold value of the comparator 36. The switch SW2-2 is configured to be turned on / off simultaneously with the switch SW2-1, and the switch SW2-2 is closed (O
N) has a function of substantially switching the resistance value of the voltage dividing resistor R3 to a predetermined resistance value. Further, the cathode terminal of the LED 42 forming the discrimination signal detecting means is connected to the inverting output terminal of the latch circuit 38. And LE
The anode terminal of D42 is connected to the collector terminal of the transistor Q1 whose ON / OFF is controlled by the voltage value of the cathode terminal of the diode D1. The control circuit 41 does not require the switch SW1 and the check terminal 34 shown in FIG.

Next, a method of adjusting the output of the photo interrupter 20a using the control circuit configured as described above will be described with reference to the time chart of FIG.

First, the switches SW2-1 and SW2-
2 is simultaneously closed (ON). In this case, the input terminal A of the pulse generator 24 becomes 0, and the pulse generator 24 generates the pulse signal in a state that does not depend on the control signal from the CPU. Note that this circuit can also be configured using an OR gate 44 as shown in FIG.

Next, according to the pulse signal, the LED 28
The pulsed light emitted from the phototransistor 30
The light is received by and is supplied to the comparator 36 as an electric signal via the amplifier 32. In this case, the threshold value supplied to the + terminal of the comparator 36 is the switch SW2-2.
Is closed (ON),

[0034]

[Equation 1]

The adjustment level V _TEST is set to. Here, the adjustment level V _TEST is a desired output voltage setting value of the amplifier 32 when the film F is not provided. The threshold value switching means can also be configured as shown in FIG.

Next, in this state, the variable resistor VR is gradually changed from a low resistance state to a high resistance value. In this case, the output voltage of the comparator 36 is initially 1
Therefore, the inverting output terminal of the latch circuit 38 is in the 0 state. On the other hand, transistor Q
1 is ON when the switch SW2-1 is closed, and the LED 42 is in a lighting state. Therefore, when the resistance value of the variable resistor VR is increased, the output of the comparator 36 is inverted when the input voltage of the negative input terminal of the amplifier 32 becomes equal to or higher than the adjustment level V _TEST . At this time, the state of the inverting output terminal of the latch circuit 38 is also inverted and L
The ED 42 goes out. In this state, the variable resistor VR is fixed. In this case, the voltage level of the input terminal of the amplifier 32 is set to the desired level. In this way, the output of the photo interrupter 20a can be adjusted while visually confirming that the LED 42 changes from a lighting state to a non-lighting state without using a measuring instrument such as an oscilloscope, a digital voltmeter, or a tester. . After adjusting the output, if the switches SW2-1 and SW2-2 are opened (OFF), the LED 42 is turned off and the control circuit 41 is also in a normal operating state.

In the second embodiment described above,
Although the operation of the pulse generator 24 is made independent of the CPU by the switch SW2-1, the same operation can be realized by a control signal from the CPU. in this case,
The diode D1 and the switch SW2-1 are unnecessary. Although the LED 42 is used as the notification means in the present embodiment, other notification means such as an electronic buzzer may be used.

[0038]

As described above, according to the output adjusting circuit of the photo interrupter according to the present invention, the continuous light emission state is set by the light emission state switching means connected to the pulse generator, and in this state, a simple measuring means such as a tester is provided. Can be used to adjust the level of the output signal very easily.

Further, as described above, the discrimination signal is detected in a state in which the threshold value of the discrimination means for discriminating the presence or absence of the detection target is switched to a level without the detection target without switching the pulsed emission light to the continuous emission light. With such a configuration, the measuring means such as the tester is not required, and the output can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a first embodiment to which an output adjusting circuit of a photo interrupter according to the present invention is applied.

FIG. 2 is a schematic configuration diagram of an image recording apparatus to which an output adjusting circuit of a photo interrupter according to the present invention is applied.

FIG. 3 is a circuit configuration diagram of a second embodiment of the output adjusting circuit of the photo interrupter according to the present invention.

FIG. 4 is a timing chart of the output adjustment circuit shown in FIG.

5 is a circuit configuration diagram of another embodiment of the switching means shown in FIG.

FIG. 6 is a circuit configuration diagram showing another configuration of the threshold value switching means shown in FIG.

[Explanation of symbols]

 10 ... Image recording device 20a-20d ... Photo interrupter 22 ... Control circuit 24 ... Pulse generator 28 ... LED 30 ... Photo transistor 34 ... Check terminal 36 ... Comparator 38 ... Latch circuit 42 ... LED D1 ... Diode Q1 ... Transistor R3, R4 , R5 ... Dividing resistance SW1, SW2-1, SW2-2 ... Switch VR ... Variable resistor

Claims (3)

[Claims] 1. An output adjusting circuit in a photointerrupter comprising a light emitting element which emits pulsed light in response to a pulse signal output from a pulse generator, and a light receiving element which receives the pulsed light and converts it into an electrical signal. And a light emitting state switching means connected to the pulse generator and configured to continuously emit light from the light emitting element by using the pulse signal as a continuous signal; and a level adjusting means connected to the light receiving element to adjust the level of the electric signal. An output adjustment circuit for a photo interrupter, comprising: a level detection terminal connected to the light receiving element for detecting the level of the electric signal. 2. An output adjusting circuit in a photointerrupter comprising a light emitting element which emits pulsed light by a pulse signal output from a pulse generator, and a light receiving element which receives the pulsed light and converts it into an electric signal. And a level adjusting means connected to the light receiving element for adjusting the level of the electric signal, and a discriminating means for comparing the electric signal with a predetermined threshold value and determining the presence or absence of a detection target between the light emitting element and the light receiving element. Threshold switching means connected to the input side and switching the threshold level to a desired level when there is no detection target; and an output side of the discriminating means, wherein the threshold is set to a desired level by the threshold switching means. An output adjustment circuit for a photo interrupter, comprising: a discrimination signal detecting unit that detects a discrimination signal indicating the presence or absence of a detection target from the discrimination unit. 3. The output adjusting circuit according to claim 2, wherein the discrimination signal detecting means includes a notifying means for notifying a state of the discrimination signal indicating the presence or absence of a detection target.