JPS6148194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control system suitable for using a large number of optical sensors as state detection elements in, for example, a form reading device, and involves internal correction of errors in sensitivity or detection level that occur in individual optical sensors. This invention relates to a control method for an optical sensor.

Conventionally, when using a large number of sensors to detect binary information at various detection levels, a dedicated circuit with a comparator for sensitivity adjustment and binarization has to be configured for each sensor. Ta.

There are several reasons for this; first, there are variations in sensitivity between the light emitting and light receiving elements, and mutual sensitivity adjustment is required within the device; second, the slice level for binarization is not necessarily the same. It has individual volume adjustment points for sensitivity adjustment. These adjustments must be made one by one by the adjuster, and as the number of sensors required increases, the adjustment becomes more labor-intensive, and further downsizing means that a large number of volumes must be prepared for mounting. It had the drawbacks of difficulty and increased costs.

SUMMARY OF THE INVENTION In view of this background, it is an object of the present invention to provide an improved optical sensor correction method that can automatically make necessary adjustments to individual optical sensors.

To achieve this objective, the control method of the present invention includes a plurality of optical sensors each consisting of a light-emitting element and a light-receiving element, and a device that determines the presence or absence of a medium based on the received light output of the optical sensor, which has a storage area corresponding to the optical sensor. and a memory for storing data corresponding to the amount of light emitted from the light emitting element of the optical sensor, an amplifier connected to the plurality of light emitting elements to drive the light emitting element, and an amplifier connected to the plurality of light receiving elements to selectively output light reception. and a timing control circuit that selectively controls the memory and the output means, and drives the light emitting element according to the data selected in the memory, and outputs the light reception output selected by the output means. It is characterized by output.

The present invention will be explained in more detail below based on Examples.

FIG. 1 shows a conventional example, and is a circuit diagram showing a variable amplifier and a comparator subordinate to one element of the i-th sensor among n elements, and 1 in the figure is a photodetector diode,
2 is a phototransistor, 3 is an amplifier, 4 is a gain adjustment volume, 5 is a comparator, 6 is a bias diode, and R1 to R6 are resistors. Note that the light receiving diode 1 and the phototransistor 2 are basic optical sensors, and if n optical sensors are required, n pieces of the configuration shown in FIG. 1 are required, and there are n adjustment points.

FIG. 2 shows a configuration diagram of a sensor control circuit according to an embodiment of the present invention. In the figure, 1.1 to 1.n are n light emitting elements corresponding to FIG. 1, and 2.1 to 2.n are n light receiving elements corresponding to FIG.・1, 1, 2 and 2, 2, . . . 1, n and 2, n each represent a pair of sensors. Also, the respective bias resistors are R1・1~R1・n, and R2・1~R2・
Represented by n.

7, 8, and R7 indicate a light source drive circuit, 8 indicates an amplifier, 7 indicates a drive transistor, and R7 indicates a bleed resistor. Further, 9 is a D/A converter, 10 is a first memory for gain measurement, 11 is a first register for controlling the first memory, and 12 is a register for memory selection. Further, 13 is a second memory for setting the binarization slice level, 14 is a second register for controlling the second memory, and 15 is a sensor ~
16 is a comparator that compares the contents of the memory 13 and the contents of the A/D converter 15. 1
7.1 to 17.n indicate flip-flops of the third memory 17 that store the results of comparison by the comparator 16 at respective addresses, and 18 indicates a register for reading and controlling the contents of the memory 17. Note that 19 indicates an MPU which is a logic control circuit that controls these. 20 is a control clock oscillation circuit, and 21 is a sensor timing control circuit.

FIG. 3 is an explanatory diagram showing the division of the memory areas of the first memory 10 and the second memory 13, and shows n address divisions assigned to each sensor for n sensors. have,
The contents of the memory 10 are selected by the address of the register 12, and the contents of the memory 10 are transferred to the register 14 by the register 11.
The contents of the memory 13 can be set by specifying the corresponding addresses.

In this way, each sensor 1 to n is stored in the memory 10 according to the address corresponding to any one of the sensors.
The driving conditions of the light emitting element are controlled by the comparator 16, and the level of the binarized slice of the corresponding sensor signal coming from the A/D converter 15 is controlled by the comparator 16 according to the content of the corresponding address in the memory 13, and the signal is converted into a binary signal. The encoded information is stored in the third memory 17 in correspondence with the address, read out by the register 18, and used as control information.

That is, the sensor groups 1 to n are time-divisionally sampled using the selected addresses 1 to n', and address scanning is performed when necessary according to instructions from the MPU 19, thereby detecting operational information of the sensor groups 1 to n.
Note that in actual equipment, depending on the operation mode, the operation of all the prepared sensors or the status information of all the prepared addresses may not be necessary. It is also possible to scan by skipping unnecessary parts, and even if the required sample interval differs between addresses, this can be handled in the same way by changing the command.

Next, a method of initial setting the sensitivity level of each sensor will be explained.

The above initial setting is performed as setting of operating values after assembly at the factory, or as setting of operating conditions at power-on or readjustment.

The configuration will be explained assuming that the memory 10 and the memory 13 are volatile memories. In addition, MPU1
9 has a built-in non-volatile memory and a power supply.
Executes the initial loading program procedure with ON. When the device is first powered on, memories 10 and 13 are not set.

When the power is turned on, each address of the memory 13 is selected by the register 12, and a voltage level for initial setting is written to each address of the memory 13 via the register 14.

Next, the memory 10 is selected with the register 12, a set value of one address of the memory 10 is written through the register 11, and this set value is further increased with time.

As the set value of each address of the memory 10 read out by the address signal of the sensor timing control circuit 21 increases, the output of the D/A converter 9 increases sequentially, and accordingly, the output of the D/A converter 9 increases.
The light amount of 1・n increases, and the light receiving elements 2・1 to 2・n
The output will also increase gradually. The output of the light receiving elements 2.1 to 2.n corresponding to this address is selectively digitized by the A/D converter 15 by the control circuit 21, and the corresponding address of the memory 13 is written to the initial setting level by the comparator 16. is compared with the set value. When the output of the light-receiving element becomes larger than the set value in the comparator 16, that is, when it turns on, turn-on information is written to the corresponding address of the third memory 17 and sent via the register 18.
The value is read out by the MPU 19, stops increasing the set value at the corresponding address in the memory 10 via the register 11, and sets the initial value of one address in the memory 10. Note that each sensor is initially set under a white condition that is not obstructed by a medium or the like.

The cut-off value is set corresponding to each address of the sensor 10 one after another using the same procedure. In this way, the outputs of each sensor are all set to the same output level set by the memory 13, and the driving conditions
This means that variations between sensor elements, variations between devices, etc. are all automatically adjusted without individual operations.

Next, the memory 13 is selected with the register, and information for setting the binarization slice level of each address is written into each address of the memory 13 via the register 14, thereby completing the initial setting.

The slice level setting value for each address is determined experimentally in advance based on the amount of transmission of the medium during use and the reflectance of the black level used, compared to the initial setting of white or output without a medium. Prepare slice levels in the MPU 19 memory and use them. If you perform the above initial settings when the power is turned on or when changing the setting level, the adjustment will be completed and the device will be ready for operation.

It goes without saying that if the memory 10 and the memory 13 are composed of non-volatile PAM, the setting for each input can be omitted.

As explained above, according to the present invention, there is no adjustment element such as a polyurethane as a component, and adjustment points are eliminated as hardware, thereby eliminating the need for manual adjustment and allowing the operation of a large number of sensor elements. Since point adjustment and setting can be performed automatically, it is possible to significantly reduce the number of adjustment steps.

In addition, by centrally controlling sensor circuits that were previously prepared individually, the number of components and the circuit area used for mounting can be significantly reduced. Setting values are also digitized, and analog parts are replaced by D/A and
Since there are only input and output sections for the sensor group sandwiched between the A/D converters, it is possible to create a control circuit that is extremely stable against drift and changes over time, reducing the impact on design, cost, and performance. The effects of the present invention are extremely large.

In addition, if multiple slice detection levels are required by preparing n or more addresses for n sensors, for example, , 2. Double-feet detection that detects no medium or the presence of one medium and two or more media, which enables level judgment using multiple slice levels when the same sensor is operated at different levels, such as . In the present invention, the definition of the address and the corresponding determination level of the address are set in the control program, and by setting a plurality of addresses for a specific element, it can be set extremely easily.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional sense circuit, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional sense circuit.
Explanatory diagrams of address areas allocated in the memory 10 and the sensor 13 in the figure are shown, respectively. In the figure, 1・1~1・n are sensor light emitting parts, 2・1~
2 and n are sensor light receiving parts, 10 and 13 are first and second memories, respectively, and 9 and 15 are respectively
A D/A, A/D converter, 16 a comparator, 17 a third memory, and 19 a logic control circuit MPU.

Claims (1)

[Claims] 1. A device comprising a plurality of optical sensors each consisting of a light-emitting element and a light-receiving element, and determining the presence or absence of a medium based on the light-receiving output of the optical sensor, which has a storage area corresponding to the optical sensor, and has a storage area corresponding to the optical sensor; a memory for storing data corresponding to the amount of light emitted by the light emitting device; an amplifier connected to the plurality of light emitting elements to drive the light emitting elements; a means connected to the plurality of light receiving elements for selectively outputting light reception output; An optical sensor comprising: a timing control circuit that selectively controls output means; the light emitting element is driven by the selected data of the memory; and the output means outputs the selected light reception output. control method.