JPH07187449A - Lateral dislocation correction device for paper - Google Patents

Abstract

PURPOSE:To attain the detection and correction of the lateral dislocation of paper to be conveyed with high accuracy. CONSTITUTION:This device is provided with a reading means which reads paper to be conveyed, a paper end detecting means 8 which detects the end of paper from the data read by the reading means, a paper end determining means 9 which determines reference position data and measured position data from the data of paper end for each of prescribed multiple lines detected by the paper end detecting means 8, and a paper dislocation detecting means 10 which detects the amount and direction of the dislocation of paper from the reference position data and measured position data determined by the paper end determining means 9. It corrects the dislocation of paper by controlling a correction mechanism with a control means 12 according to the results detected by the paper dislocation detecting means 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lateral deviation correction device for a sheet conveyed by a conveying roller or the like.

[0002]

2. Description of the Related Art Conventionally, in copying machines and printers,
The paper may skew and cause horizontal misalignment.When the paper laterally misaligns, the image formed on the paper may be skewed or misaligned, and the paper may wrinkle or jam after fixing. Has become.

For this reason, various devices for correcting the lateral deviation of the paper have been proposed or put into practical use.
There are those disclosed in Japanese Patent Laid-Open No. 175545 and Japanese Patent Laid-Open No. 60-118542. These lateral misalignment correction devices detect lateral misalignment of the paper by detecting left and right ends of the paper with sensors, and perform lateral misalignment correction based on the detection result.

[0004]

When the sheet is laterally displaced after the leading edge of the sheet has passed the sensor, the lateral displacement cannot be detected, and therefore, sufficient lateral displacement correction cannot be performed.

[0005]

The invention according to claim 1 is
Reading means for reading the conveyed paper, paper edge detecting means for detecting the paper edge from the read data read by the reading means, and paper edge data for each predetermined plurality of lines detected by the paper edge detecting means A sheet edge determining means for determining the reference position data and the measurement position data of the sheet edge portion from the sheet, and a sheet for detecting the amount and direction of the sheet deviation from the reference position data and the measurement position data determined by the sheet edge determining means. A misregistration detection unit and a control unit that controls the correction mechanism to correct the misregistration of the sheet based on the detection result of the sheet misregistration detection unit are provided.

According to a second aspect of the invention, in the first aspect of the invention, the position data of the sheet edge portion first determined by the sheet edge determining means after the reading by the reading means is started is used as the reference position data. The position data of the edge of the paper determined after the first time was used as the measurement position data.

According to a third aspect of the present invention, in the first aspect of the present invention, the sheet edge determining means obtains the maximum value from the data of the sheet edge portions for every predetermined plural lines detected by the sheet edge detecting means. The value was used as reference position data or measurement position data at the edge of the paper.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the sheet misregistration detecting means detects a difference between the reference position data determined by the sheet edge determining means and the measurement position data as a misregistration amount to obtain a reference value. The magnitude relationship between the position data and the measured position data is detected as the shift direction.

[0009]

According to the first aspect of the present invention, when the reading means reads the conveyed sheet, the sheet edge detecting means detects the edge portion of the sheet from the read data. Then, the paper edge determination means determines the reference position data and the measurement position data of the paper edge based on the data of the paper edge for each of a plurality of predetermined lines detected by the paper edge detection means. Then, from the reference position data and the measurement position data, the paper misregistration detection unit detects the misregistration amount and the misalignment direction of the paper, and the control unit controls the correction mechanism based on the detection result of the paper misregistration detection unit to perform correction. The mechanism corrects the misalignment of the paper.

According to the second aspect of the present invention, the sheet edge determining means determines the sheet edge position data from the sheet edge data for each of a plurality of predetermined lines detected by the sheet edge detecting means. The position data determined first after the reading is started is the reference position data, and the position data determined after the second reading is the measured position data.

According to the third aspect of the present invention, the maximum value among the data of the paper edge portions for each predetermined plurality of lines detected by the paper edge detection means is the reference position data of the paper edge portions within the range of the plurality of lines. Alternatively, the measurement position data is used.

According to another aspect of the present invention, the difference between the reference position data determined by the sheet edge determining unit and the measurement position data is detected as the amount of deviation in the sheet deviation detection unit, and the reference position data and the measurement position data are detected. The magnitude relationship with and is detected as the deviation direction.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. First, FIG. 2 shows a schematic structure of a reading unit for reading the conveyed paper 1, and a honeycomb for correcting the diffused light from the light source 2 and the light source 2 into a substantially parallel light at a position facing the conveyance path of the paper 1. A filter 3 having a structure is provided, and a reading sensor 4 that is a reading unit is provided at a position facing the filter 3 across the transport path. The filter 3 has a diameter of 1 × 1 mm and a height of 20 mm. Therefore, the light emitted from the filter 3 is ½.
The light becomes a substantially parallel light with an inclination of 0. When the sheet 1 passes between the filter 3 and the reading sensor 4, the reading sensor 4 outputs analog signals of dark output and bright output as shown in FIG.

Further, the conveyed sheet 1 is vertically displaced between the filter 3 and the reading sensor 4, but the filter 3
Assuming that the distance between the sheet and the reading sensor 4 is about 3 mm, a reading error of 3 mm × 1/20 = 0.15 mm is generated when the sheet 1 passes above and below the sheet 1 as shown in FIG. Occurs. And this reading sensor 4 is 8
If the maximum reading width is 256 mm, the total number of pixels is 2.
Since 048 pixels and 0.125 mm per pixel,
The reading error is about one pixel.

Next, FIG. 1 is a block diagram showing a schematic structure of the entire lateral deviation correcting device. An amplifier 5 for expanding an analog signal from the reading sensor 4 and an analog signal expanded by the amplifier 5 are converted into digital signals. The A / D converter 6 for conversion compares the converted digital signal with predetermined binarization level data, and the comparison result shows the binarization signal ("H" if paper is present) as shown in FIG. And a comparator 7 for outputting "L" when there is no paper. Further, from the paper edge detection unit 8 which is a paper edge detection unit that detects the paper edge based on the output from the comparator 7, and the data of the paper edge for each predetermined plural lines detected by the paper edge detection unit 8, Paper edge determining unit 9 which is a paper edge determining unit that determines the edge edge position data (reference position data, measurement position data) in the plurality of lines, and the reference position data and the measurement position data determined by the paper edge determining unit 9. The sheet misalignment detection unit 10 that is a sheet misalignment detection unit that detects the amount of misalignment and the direction of misalignment of the sheet 1 and a correction mechanism (not shown) based on the amount of misalignment and the direction of misalignment detected by the paper misalignment detector 10. In addition, a control unit 12 that is a control unit that outputs a reading start signal to the timing generation unit 11 is provided.

Here, the timing of the paper misregistration detection is shown in FIG.
It will be described based on. First, when a sensor (not shown) detects that the paper 1 is conveyed to above the reading sensor 4, the control unit 12 to which the detection result is input sets the detection start signal to “H” at a predetermined timing. . When the detection start signal becomes “H”, the timing generation unit 11 outputs a sample signal that becomes “H” every predetermined period (for example, 1 second). Further, the reading start signal to the reading sensor 4 is 1
It is output from the timing generation unit 11 every / 64 seconds, so that the edge of the paper is detected 64 times (line) during one cycle of the sample signal. Then, when the sample signal first becomes "H" after the detection start signal becomes "H", the position data determined by the paper edge determining unit 9 is used as the reference position data, and hereinafter, the sample signal becomes "H". H "
The position data determined by the paper edge determination unit 9 each time becomes the measurement position data. Further, the deviation amount and the deviation direction of the paper 1 are determined in the paper deviation detecting unit 10 based on the reference position data and the measurement position data.

Next, FIG. 6 shows the structure of the paper edge detection unit 8, and FIG. 7 shows a timing chart for paper edge detection. The sheet edge detection unit 8 receives the detection start signal and the output (binarization signal) from the comparator 7, and the AND gate 13,
A flip-flop 14 to which a read clock and a read start signal are input, an output from the AND gate 13, a read clock and an output from the flip-flop 14 are input 1
It is formed of a 2-bit counter 15 and a 12-bit flip-flop 16 connected to the counter 15.

When the control unit 12 outputs the detection start signal, the timing generation unit 11 outputs the read start signal to the read sensor 4 in a predetermined cycle in synchronization with the read clock, and the end portion of the paper 1 is read. Reading is started, and a binary signal is output from the comparator 7 based on the read data from the reading sensor 4. Then, the signal (signal) when the detection start signal and the binarized signal output from the comparator 7 are input to the AND gate 13 is input to the count enable terminal of the counter 15 to detect the sheet 1. Yes (comparator 7
While the output of is "H"), it counts up in synchronization with the read clock.

Prior to this count-up operation,
The read start signal is read by the flip-flop 14, and a signal (signal) which is latched and inverted by one clock of the read clock is input to the clear terminal of the counter 15, so that the outputs Q1 to Q11 are cleared in advance.

The flip-flop 16 latches the outputs Q1 to Q11 of the counter 15 at the next rising of the reading start signal and outputs them to the sheet edge determining section 9 as the data of the sheet edge of the current line. Then, this processing is continued until the detection start signal becomes "L" and the detection is completed.

The counter 15 and the flip-flop 1
6 is set to 12 bits because the reading sensor 4 has 2048 pixels, and if the number of pixels of the reading sensor changes, this bit configuration also changes. Therefore, the counter 15 and the flip-flop 16 are limited to 12 bits. It is not something that will be done.

Next, FIG. 8 shows the structure of the paper edge determination unit 9, and FIG. 9 shows a timing chart for determining the paper edge. The sheet edge determination unit 9 is formed by an AND gate 17, an OR gate 18, a flip-flop 19, a comparator 20, flip-flops 21, 22 and the like.

A detection start signal is output from the control unit 12,
When the paper edge detection unit 8 detects the data of the paper edge portion in synchronization with the reading start signal, the paper edge determination unit 9 inputs the first latch signal to the clock terminal of the flip-flop 19 via the OR gate 18. The data at the edge of the paper at that time is latched by the flip-flop 19 as maximum value data (point A). In the comparator 20, the flip-flop 19
The maximum value data latched in step 2 is compared with the data at the edge of the sheet obtained thereafter to compare the magnitude relationship. And
If (maximum value data) <(data at edge of paper),
The signal from the comparator 20 becomes "H", and the AND gate 17 takes the AND with the maximum value latch signal,
The OR gate 18 is connected to the clock terminal of the flip-flop 19.
The maximum value data is updated by inputting via (point B).

After the detection of the maximum value data of a predetermined section, the flip-flop 2 is detected for the first time after the detection is started.
In 1, the maximum value data is latched by the reference position latch signal and is output to the paper misregistration detection unit 10 as the reference position data.

In the flip-flop 22, the maximum value data is latched by the sample signal and is output to the paper misregistration detection unit 10 as measurement position data.

Next, FIG. 10 shows the paper misregistration detection unit 10 described above.
FIG. 11 shows a structure of the above, and FIG. 11 shows a timing chart of paper misalignment detection. The paper misregistration detection unit 10 and a comparator 23 that compares the position data (reference position data) of the paper end determined first by the paper end determination unit 9 with the position data (measured position data) determined after the second time. It is formed by subtractors 24 and 25 that calculate the difference between the reference position data and the measured position data, and a selector 26 that determines which of the subtraction results obtained by the subtracters 24 and 25 is selected.

A detection start signal is output from the control unit 12,
When a sample signal is generated from the timing generator 11,
The paper edge determination unit 9 determines the reference position data (for example, 30) by the first sampling signal, and the reference position data is output to the paper misregistration detection unit 10. And
Each time the sample signal is generated for the second time, the third time, or the like, the paper edge determination unit 9 outputs the measurement position data. Then, the reference position data and the measurement position data are judged to be larger or smaller by the comparator 23, and (reference position data) <
In the case of (measurement position data), an "H" signal is output,
In other cases, an “L” signal is output (signal).

At this time, the subtractor 24 simultaneously calculates (reference position data)-(measurement position data), and the subtractor 25 calculates (measurement position data)-(reference position data).
Is calculated and output to the selector 26 (signal,
). Then, according to the comparison result of the comparator 23 among the calculation results of the subtracters 24 and 25, (reference position data) <
In the case of (measurement position data), the calculation result of the subtractor 25 is
In other cases, the calculation result of the subtractor 24 is output to the control unit 12 as deviation amount data.

Further, the comparator 23 outputs the magnitude relation between the reference position data and the measured position data to the control unit 12 as data indicating the deviation direction. Specifically, when the paper 1 is shifted to the right, the measurement position data becomes large. Therefore, when the output of the comparator 23 is "H", the paper is shifted to the right and to the left when the output of the comparator 23 is "L". Show.

Next, the control unit 12 controls the CPU and the RO.
It is formed of peripheral devices such as M and RAM. Also,
As a correction mechanism that is controlled by the control unit 12 and corrects the misalignment of the paper 1, a well-known mechanism that has been conventionally used is used. For example, a fixing unit that press-fixes the paper 1 conveys the paper 1. And rotating the fixing unit in a right-and-left direction and changing the pressure applied to the left and right of the fixing unit by driving a motor or the like.

Here, a series of operations for paper misalignment correction are shown in FIG.
It will be described based on the flowchart of FIG. First, paper 1
The sensor determines whether or not the sheet is passing between the reading sensor 4 and the filter 3 (step 1). If the sensor is "on", it is determined that the sheet 1 is passing, and the sheet 1 is misaligned. A detection start signal for starting the amount detection is output (step 2). Then, the binarization level for performing this detection is output to the comparator 7 (step 3), and the deviation amount of the sheet 1 and the deviation direction data output from the sheet deviation detection unit 10 are taken in (step 3). 4).

Then, it is judged whether or not the amount of deviation taken in is equal to or larger than a predetermined value which requires correction (step 5), and when it is judged that correction is necessary, the deviation direction is judged (step 6). . Based on the result of the determination of the displacement direction, if the displacement is to the right, left alignment correction is performed (step 7),
If it is shifted to the left, right adjustment is performed (step 8). Then, after this correction is performed, it is determined whether or not the detection is completed (step 9). If not completed, the process returns to step 4, and if completed, a series of correction operations is completed. If it is determined in step 5 that the deviation amount does not need to be corrected, the determination in step 9 is made.

[0033]

As described above, according to the present invention, the reading means for reading the conveyed paper, the paper edge detecting means for detecting the edge of the paper from the read data read by the reading means, and the paper. Paper edge determining means for determining reference position data and measurement position data of the edge of the sheet from data of the edge of each predetermined plurality of lines detected by the edge detecting means, and reference position data determined by the edge determining means. A sheet deviation detecting means for detecting a deviation amount and a deviation direction of the sheet from the measurement position data and a control means for controlling the correction mechanism so as to correct the deviation of the sheet based on the detection result of the sheet deviation detecting means. Since the sheet is provided, even if the leading edge of the conveyed sheet is in a straight-ahead state and a lateral deviation occurs during transportation, the lateral deviation can be detected and corrected. Therefore, the lateral deviation of the sheet can be corrected. High precision It can be performed in, with or inclined image formed on the sheet, wrinkles are closer to the paper, the effect of such paper can be reliably prevented or jammed.

According to the second aspect of the invention, as described above, in the first aspect of the invention, the position data of the sheet edge portion first determined by the sheet edge determining means after the reading by the reading means is started is used as the reference position. As the data, the position data of the edge of the paper determined after the second time is used as the measurement position data.
Even if the sheet is laterally displaced after the reading by the reading means is started, the lateral deviation can be detected, and therefore the lateral deviation of the sheet can be corrected with high accuracy.

According to the third aspect of the present invention, as described above, in the first aspect of the present invention, the paper edge determining means selects from among the data of the paper edge portion for each predetermined plural lines detected by the paper edge detecting means. Since the maximum value is obtained and the value is used as the reference position data or the measurement position data at the edge of the sheet, it is possible to reliably detect that the sheet is misaligned.

As described above, in the invention according to claim 4, in the invention according to claim 1, the paper misregistration detection means uses the difference between the reference position data and the measurement position data determined by the paper edge determination means as the misregistration amount. Since the size of the reference position data and the measured position data is detected as the misalignment direction, it is possible to reliably perform lateral misalignment correction corresponding to the misalignment amount and misalignment direction of the paper. Have.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall structure of a lateral deviation correction device according to an embodiment of the present invention.

FIG. 2 is a front view showing a schematic structure of a reading unit for reading a sheet.

FIG. 3 is an explanatory diagram showing a positional relationship between a reading sensor and a sheet, an analog signal output from the reading sensor, and an output of the reading sensor converted into a binary signal.

FIG. 4 is an explanatory diagram of a reading error that occurs when a conveyed sheet is vertically displaced between a filter and a reading sensor.

FIG. 5 is a timing chart of paper misregistration detection.

FIG. 6 is a block diagram showing a structure of a paper edge detection unit.

FIG. 7 is a timing chart of sheet edge detection.

FIG. 8 is a block diagram showing a structure of a paper edge determination unit.

FIG. 9 is a timing chart for determining a sheet edge.

FIG. 10 is a block diagram showing a structure of a paper misregistration detection unit.

FIG. 11 is a timing chart of paper misalignment detection.

FIG. 12 is a flowchart illustrating a series of operations for paper misalignment correction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 paper 4 reading means 8 paper edge detecting means 9 paper edge determining means 10 paper misalignment detecting means 12 control means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 21/14

Claims (4)

[Claims] 1. A reading unit for reading a conveyed sheet, a sheet edge detecting unit for detecting an edge of a sheet from read data read by the reading unit, and a plurality of predetermined lines for each line detected by the sheet edge detecting unit. Paper edge determining means for determining the reference position data and measurement position data for the edge of the paper from the data for the edge of the paper, and the amount and deviation of the paper from the reference position data and the measurement position data determined by the edge determining means. A lateral misalignment correction of a sheet, which is provided with a paper misalignment detecting means for detecting a direction and a control means for controlling a correction mechanism so as to correct the misalignment of the paper based on the detection result of the paper misalignment detecting means. apparatus. 2. The position data of the paper edge determined first by the paper edge determining device after the reading by the reading device is started is used as reference position data, and the position data of the paper edge determined after the second time is measured position. 2. The sheet lateral misalignment correction device according to claim 1, wherein the data is data. 3. The paper edge determination means obtains a maximum value from the data of the paper edge portion for each of a plurality of predetermined lines detected by the paper edge detection means, and the value is used as the reference position data or measurement position of the paper edge portion. 2. The sheet lateral misalignment correction device according to claim 1, wherein the data is data. 4. The paper misregistration detection means detects the difference between the reference position data determined by the paper edge determination means and the measurement position data as a deviation amount, and the magnitude relationship between the reference position data and the measurement position data is taken as the deviation direction. The lateral misalignment correction device for a sheet according to claim 1, wherein the lateral misalignment correction device detects the lateral deviation.