JPH07113542B2 - Paper thickness detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a paper thickness detection device, and particularly to a paper of an optical character reading (hereinafter, referred to as OCR) device that uses a plurality of types of paper having different paper thicknesses. The present invention relates to a thickness detection device.

[Prior Art] In an OCR device, paper thickness is detected in order to detect double feeding of conveyed paper and mixing of undesignated paper (paper with different paper thickness).

FIG. 3 is a system block diagram for explaining a conventional paper thickness detecting device.

When detecting the thickness of a piece of paper, the OCR device measures the thickness at multiple locations and determines a representative value that indicates the thickness of the paper from the multiple measured values with variations. is doing.

The paper thickness sensor 6 is arranged such that the light emitter and the light receiver face each other, and when the paper being conveyed between them is blocked, the paper thickness sensor 6 photoelectrically converts the amount of light transmission obtained by the light receiver. The data is measured, and the state of "paper present" on the sensor 6 or the state of "no paper" on the sensor 6 is detected from the value of the measured paper thickness data. Paper thickness data (analog value) measured by the paper thickness sensor 6,
The comparator 5 compares the reference values set in the level setters 1 to 4 according to the thickness of the paper to be measured, that is, a plurality of slice levels, respectively. Paper thickness sensor 6
"No paper" based on the value of the paper thickness data measured by
When detecting the state, the counting unit 20 is reset.

The "paperless" state is detected as follows. When the paper is not on the paper thickness sensor 6, that is, when there is no obstruction between the projector and the light receiver, the paper thickness sensor 6 shown in FIG.
As can be seen from the output (standard time data), the amount of light transmission increases. Therefore, when the output level of the paper thickness sensor 6 is remarkably high as compared with the case where the paper having the normal usable paper thickness blocks the space between the light emitter and the light receiver, the paper thickness sensor 6 does not have any paper on it. It is determined that there is. In particular,
The value of the paper thickness data measured by the paper thickness sensor 6 is compared with the standard level indicating the "no paper" state, and the value of the measured paper thickness data is based on the comparison result. It is determined that the value is significantly larger than the value of the paper thickness data obtained for the paper having "," that is, the "no paper" state. However, the light quantity of the projector changes due to manufacturing variations, environmental changes, aging, etc., and the output level offset value also fluctuates due to similar factors in the photoelectric conversion circuits after the receiver. Is set as a constant value determined in accordance with the variation of the offset value.

Next, based on the result of comparison between the value of the measured paper thickness data and the standard level indicating the “paperless” state, when the “paper present” state is detected, it is measured by the paper thickness sensor 6. The paper thickness data and the slice levels set in the slice level setting units 1 to 4 according to each paper thickness are compared by the comparing unit 5 corresponding to the slice level. For each sample clock synchronized with the paper conveyance, the comparison result of the comparator 5 in the software reading section 16, that is, the binarized signal "1" indicating whether the paper thickness data is below the slice level or not.
/ "0" is detected, and the corresponding count unit 5 is counted up according to the detection result. This process is repeatedly executed until one sheet of paper passes over the paper thickness sensor 6. Here, when the state of "with paper" is changed to the state of "without paper", that is, when the end of the paper is detected, the determination unit 21 determines the count value of the counting unit 5 corresponding to each paper thickness, that is, "1". The paper thickness corresponding to the counting unit 5 indicating a value exceeding the majority of the total number of measurements was determined as the actually measured paper thickness. However, when there are a plurality of counting units 5 that exceed the majority, the heavier paper thickness is adopted.

In this method, the level setters 1 to 4 and the comparator 5 are composed of hardware. Incidentally, the sheet thickness is expressed by the weight of 1 m ^2/1000 sheets of paper, for example paper thickness 55kg is 1 m ² × 1000 sheets 55k
The paper thickness of g is shown.

FIG. 4 is a diagram for explaining the paper thickness detection operation of FIG.
A 70 kg paper is scanned by the paper thickness sensor, and binary data obtained as a result of slicing with hardware for each paper thickness is captured at the timing of the sample clock.

For example, if the paper thickness data obtained from the paper thickness sensor 6 is lower than the slice level value of 55 kg set in the level setter 1, the comparison result of the comparison unit 5 becomes "1", and the paper thickness 55 kg. The counting section 20 for counting up. If the paper thickness data obtained from the paper thickness sensor 6 is below the value of the slice level of 70 kg set in the level setter 2, the counting unit 20 for the paper thickness 70 kg is counted up. Similarly, if the paper thickness data is below the slice level value of 90 kg or 110 kg, the counting unit 20 for the paper thickness of 90 kg or 110 kg is counted up. What is “1” in the paper thickness comparison result shown in FIG. From the comparison between the paper thickness data and the slice level for each paper thickness, it means that the paper thickness data is below the slice level, and indicates that the corresponding counting unit 20 has counted up.
"0" means not. from this result,
The paper thickness for which the frequency of occurrence of "1" exceeds the majority of the total number of measurements for one sheet (the paper thickness corresponding to the counting unit 20 that has been counted up for the majority of the total number of measurements) is the paper of the measurement target. It is determined to be thick. When there is a plurality of paper thicknesses in which the frequency of occurrence of "1" exceeds the majority of the total number of measurements for one paper, the heavier paper thickness is determined as the paper thickness of the paper. However, in this method, since the slice level is fixed by the setting by hardware, when the output of the paper thickness sensor 6 is totally lowered due to the environmental change or the aged change as shown by the broken line in the figure. The paper thickness was erroneously detected. In such a case, it is necessary to correct the output level of the sensor, and as a known example for correcting the output level of the sensor, there is an "optical reading device level adjusting mechanism" (Japanese Patent Laid-Open No. 03-135159).

[Problems to be Solved by the Invention] The above-described conventional paper thickness detection apparatus has a plurality of paper thickness comparators, and since the output is binarized by slicing by hardware, a paper thickness sensor and a slice If the hardware is affected by environmental changes, aging changes, etc., the thickness of the paper is erroneously detected, and thus the hardware must be readjusted and maintained.

An object of the present invention is to provide a paper thickness detection device that does not require readjustment or maintenance of hardware by correcting the slice value of paper thickness data by software.

[Means for Solving the Problems] The paper thickness detection device of the present invention is based on the amount of transmitted light obtained by transmitting a paper sheet passing between them, in which a light projector and a light receiver are arranged to face each other. A sheet thickness sensor for detecting the presence or absence of a sheet between the projector and the light receiver based on the measurement result while measuring the sheet thickness at a plurality of positions of the sheet as sheet thickness data. An A / D converter for converting the paper thickness data into a digital value, a reading unit for reading the A / D converted paper thickness data according to a predetermined sample clock, and a plurality of slice levels depending on the paper thickness value are set in advance. A slice level setting unit that is set, and a plurality of first comparators that compare the paper thickness data read by the reading unit and the plurality of slice levels for each paper thickness corresponding to the slice level. , The first And a determination unit that determines the paper thickness of the paper sheet based on the comparison result in the comparator, and corresponds to the digital value paper thickness data when there is no paper sheet between the projector and the light receiver. The standard level storage unit that stores the standard level to be stored in advance, and the paper thickness sensor, when the paper thickness sensor determines that there is no paper sheet between the projector and the light receiver, the paper read by the reading unit. A second comparator that compares the thickness data with a standard level stored in advance in the standard level storage unit, and a plurality of slice level setting units that are stored in the slice level setting unit according to a comparison result in the second comparator. When the end of the paper thickness detection for the paper sheet is detected by the paper thickness sensor and the first correction means for correcting all of the slice levels,
A means for calculating an average value of the paper thickness data of the digital value obtained while the paper sheet is present between the projector and the light receiver, and paper thickness data corresponding to the paper thickness of the paper sheet. A standard value storage unit that stores the standard value of the standard value in advance, a third comparator that compares the average value with the standard value,
Based on the comparison result in the comparator, of the plurality of slice levels stored in the slice level setting unit,
Second correction means for correcting only the slice level corresponding to the paper thickness corresponding to the standard value is provided.

EXAMPLES Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram for explaining the paper thickness detecting device of the present invention.

In the paper thickness sensor 6, a light transmitter and a light receiver are arranged so as to face each other, and the amount of light transmitted when the paper conveyed between them is blocked by photoelectric conversion, the paper thickness data of the paper ( Measure the analog value). Furthermore, the paper thickness sensor 6 is
From the value of the measured paper thickness data (analog value), the state where there is paper on the sensor 6 "there is paper" or the state where there is no paper on the sensor "no paper" is detected. A / D converter 11 converts the measured paper thickness data (analog value) into a digital value. Paper thickness data (digital value)
Is taken out by the software reading section 16 at each sample clock synchronized with the conveyance of the paper. That is, when the paper thickness sensor 6 detects the "paper out" state, the counting unit 20 is initialized and the digital value of the paper thickness data measured in the "paper out" state (actual measurement value 12) Is compared with the standard level indicating the "no paper" state preset in the standard level setting section 14 in the comparison section 13, and based on the difference,
Correction is applied to the slice level section 18 in which a plurality of slice levels are set according to the paper thickness. Also, the paper thickness sensor 6
When the "paper present" state is detected, the paper thickness data (digital value) is taken out by the software reading section 16 and integrated for multiple times at each sample clock synchronized with the paper conveyance. The average value calculation unit 15 adds up. It should be noted that the detection of the "no paper" state or the "paper present" state by the paper thickness sensor 6 is performed by the same method as that described in the conventional art.

When the state of “with paper” is changed to the state of “without paper”, that is, when the edge of the paper is detected by the paper thickness sensor 6,
The average value of the paper thickness data is obtained from the values integrated by the integrated average value calculation unit 15.

On the other hand, a value corresponding to the designated paper thickness value of the paper currently being conveyed (paper thickness of the paper to be read) is stored in advance in the standard value storage unit 17 as the standard value of the paper thickness data. That is, data representing the output level of the standard paper thickness sensor 6 corresponding to the designated paper thickness as a digital value is stored in the standard value storage unit 17 in advance. The comparison unit 22 compares the average value calculated by the integrated average value calculation unit 15 with the standard value of the paper thickness data stored in the standard value storage unit 17, and corrects the slice level unit 18 based on the difference. The paper thickness data read by the software reading unit 16 is compared by the comparing unit 19 with the slice level set in the slice level unit 18 according to each paper thickness. As a result, when the paper thickness data falls below the slice level of the comparison target set according to the paper thickness, the corresponding counting unit 20 is counted up. When the state of "with paper" changes to the state of "without paper", that is, when the end of the paper is detected, the determination unit 21 checks each count value of the counting unit 20 according to the thickness of each paper, and performs all measurements. The paper thickness corresponding to the counting unit 20 that exceeded the majority of the number of times was determined as the actually measured paper thickness. However, if there are a plurality of counting units 20 that exceed the majority, the heavier paper thickness is adopted.

In the present embodiment, there are two methods for applying correction to the slice level preset in the slice level unit 18 according to the paper thickness.

One is the paper thickness sensor 6 when there is no paper on it.
Is used as the actual measurement level of the paper thickness data, and it is compared with the preset standard level of the paper thickness data in the “no paper” state. Based on the deviation between the two, a plurality of preset paper thickness data are set. The correction is applied uniformly to the slice level.

On the other hand, while detecting the thickness of the paper being conveyed, the paper thickness data is accumulated in parallel with it, and the average value of the paper thickness data is calculated based on the accumulated value. Based on the result of comparison with the standard value of the paper thickness data for the paper thickness, only the slice level for the paper thickness corresponding to the standard value is corrected. This correction result is applied when the sheet thickness of the next sheet to be conveyed is detected.

Next, the case where the reading unit 16 of the software of this embodiment obtains the paper thickness data by using this correction method will be described with reference to the flowchart of FIG. In step 101, the output data of the paper thickness sensor 6 and the A / D converter 11 are read.

Next, at step 102, the paper thickness sensor 6 determines the "paper out" state, the "paper present" state, and the end of the paper. The slice level set in the slice level section 18 is corrected based on the deviation between the measured value and the standard value preset as the paper thickness data indicating the "no paper" state. Then, the counting section 19 provided therein is reset, and it is determined whether or not the determination in step 117 is completed.

Next, in the case of the “with paper” state, the output data of the paper thickness sensor 6 is integrated in step 105, the paper thickness data is compared with the slice level of the paper thickness 55 kg in step 106, and if applicable, that is, the paper thickness 55 if the data is below that slice level
The count section 20 of kg is incremented to "+1", and the paper thickness is 70k in step 107.
If it corresponds to the slice level of g, the count section 20 is incremented by "+1", and in step 108 it is compared with the slice level of 90 kg of paper thickness. In 109, the slice level of the paper thickness of 110 kg is compared, and if it corresponds, the counting unit 20 is incremented by "+1", and in Step 110, the counting unit exceeding 110 kg is incremented by "+1". Therefore, if the paper thickness is not yet determined, the process returns to step 101. If you detect the edge of the paper, step 1
The average value is calculated from the paper thickness data accumulated in 03, and from the deviation between the average value of the paper thickness data and the standard value of the corresponding paper thickness, among the preset slice levels in the slice level section 18, the aforementioned standard value The slice level corresponding to the paper thickness according to is corrected and applied to the paper thickness detection of the paper that is conveyed next. In step 104, the paper thickness of the paper whose end is detected is determined from the value indicated by the counting unit 20 for each paper thickness.

[Effects of the Invention] As described above, according to the present invention, by correcting the slice value of the paper thickness data by software, it is possible to prevent variations in the output level due to variations in manufacturing of the paper thickness sensor, environmental changes, and secular changes. It is not necessary to readjust the hardware each time as in the case of the detection device, and there is an effect that maintenance is not necessary and the paper thickness can always be detected with reliability.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
FIG. 3 is a flow chart of the software section of the figure, FIG. 3 is a block diagram for explaining a conventional paper thickness detecting device, and FIG. 4 is a diagram for explaining the operation of FIG. 6 ... Paper thickness sensor, 11 ... A / D converter, 13 ... Comparison section, 14 ... Standard level setting section, 15 ... Integrated average value calculation section, 16 ... Software reading section, 17 ... Standard value storage section, 18 ... Slice level section with paper thickness 55 kg to 110 kg, 19 ...
… Comparison section, 20 …… Count section, 21 …… Decision section, 22 …… Comparison section

Claims (1)

[Claims] 1. A light emitter and a light receiver are arranged to face each other,
Based on the amount of transmitted light obtained by passing through the paper sheets passing between them, while measuring the paper thickness at a plurality of locations of the paper sheet as paper thickness data, based on the measurement result,
A paper thickness sensor that detects the presence or absence of paper sheets between the light emitter and the light receiver, an A-D converter that converts the paper thickness data into a digital value, and the A-D converted paper thickness data in a predetermined manner. A reading unit that reads according to a sample clock, a slice level setting unit that sets a plurality of slice levels in advance according to the paper thickness value, the paper thickness data read by the reading unit, and the plurality of slice levels. With a plurality of first comparators that compare each sheet thickness corresponding to the slice level, and a determination unit that determines the sheet thickness of the paper sheet based on the comparison result in the first comparator. A standard level storage unit that stores in advance a standard level corresponding to the digital thickness paper thickness data when there is no paper sheet between the projector and the light receiver; and the projector using the paper thickness sensor. And a second step of comparing the paper thickness data read by the reading section with a standard level stored in advance in the standard level storage section when it is determined that there is no sheet between the light receivers. Of the plurality of slice levels stored in the slice level setting unit according to the comparison result of the second comparator, and the paper thickness sensor, When the end of the paper thickness detection for the paper sheet is detected, the average value of the digital paper thickness data obtained while the paper sheet exists between the projector and the light receiver is calculated. Means, a standard value storage unit that stores in advance a standard value of paper thickness data corresponding to the paper thickness of the paper sheet, a third comparator that compares the average value with the standard value, and the third Based on the comparison result in the comparator of A plurality of slice levels stored in the slice level setting unit, and a second correction unit that corrects only the slice level corresponding to the paper thickness corresponding to the standard value. apparatus.