JPH0786536B2 - Photo sensor circuit for medium detection - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensor circuit for detecting a medium by combining a light emitting element and a light emitting element, and in particular, to automatically adjust an output voltage level of a light receiving element. The present invention relates to a photo sensor circuit to be adjusted.

[Conventional technology]

In a conventional medium detection photosensor circuit in which a light emitting element and a light emitting element are combined, a method of adjusting a current flowing through the light emitting element or a gain of an output voltage amplifier of the light receiving element by a variable resistor is generally used.

[Problems to be Solved by the Invention]

The conventional method as described above has the drawback that it requires an adjustment cost because it is a manual adjustment.
Further, there is a drawback that it cannot follow the decrease in the output voltage level due to the dust adhering to the sensor.

[Means for Solving the Problems]

The medium detection photosensor of the present invention includes a light emitting element, a current adjusting circuit that adjusts a current supplied to the light emitting element, a light emitting element lighting circuit that controls lighting of the light emitting element, and a current supplied to the light emitting element. An initial value setting buffer that stores an initial value, a light receiving element that receives light from the light emitting element, a signal amplifier that amplifies the output signal of the light receiving element with a constant amplification factor, and an output signal of the signal amplifier and control An analog-digital converter that inputs a clock signal from a logic circuit and converts the output signal of the signal amplifier into digital data and outputs the digital data, and the digital data from the analog-digital converter is controlled by the control logic circuit. Memory write buffer to write to the memory and the previous from the memory write buffer in the data sample mode The memory for storing digital data, a decoder for reading the digital data read from the memory in the operation mode and converting the digital data into correction data, and the current adjusting circuit for storing the correction data and instructed by the control logic circuit. A correction value buffer to be set to, and the current initial value stored in the initial value setting buffer when a data sampling start signal is input from the outside, is set in the current adjusting circuit, and a data storage address and control are performed for the memory. And a control logic circuit for outputting a signal to store the digital data via the memory buffer and operating the light emitting element lighting circuit to light the light emitting element.

〔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 this embodiment, there are a "data sample mode" and an "operation mode". When a “data sampling start signal” is input to the control logic circuit 1 from the outside, the “operation mode” shifts to the “data sampling mode”, and the control logic circuit 1 causes the current adjustment circuit 2 to pass through the initial value setting buffer 9. To set the initial value of the current
M) 7 outputs a data storage address and a control signal to operate the light emitting element lighting circuit 12 to light the light emitting element 3. The output voltage of the light receiving element 4 at this time is input to the analog-digital converter 6 after being amplified by the signal amplifier 5 having a constant amplification factor. The analog-digital converter 6 converts the analog voltage value input from the signal amplifier 5 into digital data by the clock signal supplied from the control logic circuit 1, and writes this digital data in the RAM 7 via the memory write buffer 11.
After writing the data in the RAM 7, the control logic circuit 1 outputs the “data sampling end” signal to end the “data sampling mode” and returns to the “operation mode”.

In the "operation mode", the control logic circuit 1
Output data storage address and control signal
Read data from RAM7. The read data is the decoder 8
Is converted into correction data by the correction value buffer 10, and the correction data is set in the current adjustment circuit 2 via the correction value buffer 10. Further, the light emitting element lighting circuit 12 is operated to light the light emitting element 3. The output voltage of the light receiving element 4 at this time is amplified by the amplifier 5 and output to the outside as a constant voltage.

〔The invention's effect〕

As described above, the medium detection photosensor circuit of the present invention changes the emission intensity by changing the current of the light emitting element by converting the digital data sampled using the analog-digital converter by the decoder to change the sensor level. The effect of being able to adjust automatically, and therefore the effect of reducing the adjustment cost by the variable resistor compared with the conventional method, and following the decrease in the output voltage level due to dust adhering to the sensor The effect is that you can do it.
Further, there is an effect that the entire photo sensor circuit can be downsized and highly integrated.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1 ... Control logic circuit, 2 ... Current adjusting circuit, 3 ... Light emitting element, 4 ... Light receiving element, 5 ... Signal amplifier, 6 ... Analog-digital converter, 7 ... Memory (RA
M), 8 ... Decoder, 9 ... Initialization buffer, 10 ...
... correction value buffer, 11 ... memory write buffer, 12 ...
... Light emitting element lighting circuit.

Claims (1)

[Claims] 1. A light emitting element, a current adjusting circuit for adjusting a current supplied to the light emitting element, a light emitting element lighting circuit for controlling lighting of the light emitting element, and an initial value of a current supplied to the light emitting element are stored. An initial value setting buffer, a light receiving element that receives light from the light emitting element, a signal amplifier that amplifies the output signal of the light receiving element at a constant amplification factor, an output signal of the signal amplifier, and a clock from a control logic circuit. An analog-digital converter that inputs a signal and converts the output signal of the signal amplifier into digital data and outputs the digital data; and a memory that writes the digital data from the analog-digital converter into the memory under the control of the control logic circuit. Stores the digital data from the memory write buffer in the write buffer and the data sample mode Memory, a decoder for reading the digital data read from the memory in the operation mode and converting it into correction data, and a correction for storing the correction data and setting it in the current adjusting circuit according to an instruction from the control logic circuit. A value buffer and the current initial value stored in the initial value setting buffer when a data sampling start signal is input from the outside are set in the current adjusting circuit, and a data storage address and a control signal are output to the memory. And a control logic circuit for storing the digital data via the memory buffer and operating the light emitting element lighting circuit to light the light emitting element.