JPH08267852A - Apparatus for correcting lateral shift of paper - Google Patents

Abstract

PURPOSE: To correct a lateral shift, of a transferred paper even when the lateral shift is brought, about after a front, end part of the paper passes a detecting part for detecting the lateral shift, in a lateral shift correction device. CONSTITUTION: The position of an end part of a transferred paper in a widthwise direction orthogonal to a transferring direction is detected by a paper end-detecting means 60. The transferring amount of the paper is detected by a paper transferring amount-detecting means 61. The amount and direction of a lateral shift of the paper are detected by a lateral shift-detecting means 62 based on the detection results by the detecting means 60, 61. Moreover, a pressing force-adjusting mechanism 46 is provided to increase/decrease a pressing force at least, at the side of one ends of a pair of variable-pressure transfer rollers transferring the paper while holding the paper therebetween. The increasing/decreasing amount of the pressing force by the adjusting mechanism 46 is determined by a pressing force-controlling means 41 based on the detection result by the detecting means 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet lateral deviation correcting apparatus for correcting lateral deviation of conveyed sheets in copying machines, printers and the like.

[0002]

2. Description of the Related Art In a copying machine, a printer or the like, a conveyed sheet may be skewed to cause a lateral shift. When the lateral shift of the sheet occurs, an image formed on the sheet may be tilted or the sheet may be skewed. It may cause wrinkles or jams.

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]

In the conventional lateral misalignment correction device, if lateral misalignment occurs after the leading edge of the paper passes the position of the sensor, the lateral misalignment cannot be detected. The lateral misalignment of the paper cannot be reliably corrected.

[0005]

According to the first aspect of the present invention,
Paper edge detection means for detecting an end position in a width direction orthogonal to the transportation direction of the paper being transported on the transportation path, paper transportation amount detection means for detecting the transportation amount of the paper, and the paper edge detection means. And a lateral deviation detecting means for detecting the lateral deviation amount and lateral deviation direction of the paper being conveyed based on the detection results of the paper conveyance amount detecting means, and both end sides in the axial direction while conveying the paper in a sandwiched state. Based on the detection result of the lateral deviation detecting means, a pair of pressurizing force-conveying rollers whose pressurizing force is variable, a pressurizing force adjusting mechanism for increasing or decreasing the pressurizing force on at least one end side of the pair of pressurizing force conveying rollers A pressing force control means for determining the amount of increase or decrease of the pressing force by the pressing force adjusting mechanism is provided.

According to a second aspect of the present invention, in the first aspect of the invention, the fixing roller pair is a variable pressing force conveying roller pair.

[0007]

According to the first aspect of the present invention, the end position of the sheet being conveyed on the conveying path in the width direction orthogonal to the conveying direction is detected by the sheet end detecting means, and the conveying amount of the sheet is conveyed. The lateral deviation amount and the lateral deviation direction of the paper being conveyed are detected by the lateral deviation detecting means based on the detection results of the paper amount detecting means and the paper edge detecting means and the paper conveyance amount detecting means. Then, the increase / decrease amount of the pressing force by the pressing force adjusting mechanism for correcting the lateral deviation is determined by the pressing force control means based on the detection result of the lateral deviation detecting means, and the pressing force determined by the pressing force control means is A sheet that is laterally displaced due to a difference in the pressure applied to both ends of the variable pressure transfer roller pair is applied to the variable pressure transfer roller pair via the pressure adjustment mechanism. Thus, the lateral deviation is corrected when being held and conveyed.

According to the second aspect of the invention, it is possible to correct the lateral deviation of the sheet during fixing. Further, the pressure applied to the fixing roller pair can be weakened as needed, even when the lateral deviation is not corrected.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 14 is a block diagram showing an outline of a digital copying machine to which the present invention is applied. A document reading device 1 for reading a document.
An image memory section 2 for storing the image data of the read document, a copying apparatus 3 for executing a series of image forming processes for copying the stored image data on a sheet, and a system control apparatus 4 for controlling these. , And an operating device 5 for performing a key input to the system control device 4.

The structure of the document reading apparatus 1 will be described with reference to FIGS. 14 and 15. First, as shown in FIG.
A pressure plate 7 having an ADF function that covers the upper side of the contact glass 6 so as to be openable and closable, a plurality of conveying rollers 8 that conveys a document by the ADF function, a lamp 9 that irradiates the document on the contact glass 6 with light, and a document. A lens 10 for condensing the reflected light of the above and a CCD (Charge Coupled Device) 11 for forming an image of the reflected light condensed by the lens 10 are provided. The original image formed on the CCD 11 is converted into an analog electric signal (analog image signal).

Further, as shown in FIG. 14, the CCD 11
The image amplification circuit 12 for amplifying the analog image signal output from the CCD, the synchronization control circuit 13 for outputting a reading clock synchronized with the analog image signal output from the CCD 11, and the analog image signal amplified by the image amplification circuit 12 for each pixel. A / D conversion circuit 1 for converting into a multi-valued digital image signal
4. A shading correction circuit 15 that corrects distortion due to uneven light quantity of the converted multi-valued digital image signal, dirt on the contact glass 6, sensitivity unevenness of the CCD 11, and the like. The shading-corrected multi-valued digital image signal is converted into a digital recording image signal. An image processing circuit 16 for conversion and a reading control circuit 17 for controlling the entire document reading apparatus 1 are provided.
The shading-corrected digital recording image signal is written in the image memory unit 2 as image data.

Next, the operating device 5 has an operating panel 18
And the operation control circuit 19. On the operation panel 18, a large number of keys for designating various functions, specifically, as shown in FIG. 16, a paper size key 20, a paper type designation key 21, a paper feed stage designation key 22, a ten key 23, a start key 24, A mode clear key 25, a stop key 26, etc. are provided.

Next, the structure of the copying apparatus 3 will be described with reference to FIGS. 14 and 17. As shown in FIG. 17, a photosensitive drum 27 that is rotationally driven at a predetermined rotation speed is provided, and the surface of the photosensitive drum 27 is evenly provided around the photosensitive drum 27 at a predetermined potential. An LED (Light Emitting Diod) that forms an electrostatic latent image on the surface of the charger 28 with a grid to be charged and the photosensitive drum 27 by irradiating the surface based on a digital recording image signal.
e) Head 29, developing unit 30 that develops an electrostatic latent image to form a toner image, transfer charger 32 that transfers the toner image onto paper 31, paper 3 after the toner image has been transferred
Separation charger 3 for separating 1 from the photosensitive drum 27
3. A cleaning unit 34 for cleaning the residual toner on the photosensitive drum 27 is arranged.

Below the photoconductor drum 27 and the like, there are provided three-stage paper accommodating portions 35a to 35c for accommodating the paper 31 wound in a roll shape, and each paper accommodating portion 35a.
Feed rollers 36 for feeding the paper 31 are provided in the portions 35c.
a to 36c, cutters 37a to 37c for cutting the fed paper 31 into a predetermined length, and the like are provided.

Further, as shown in FIG. 14, in the copying apparatus 3, an LED writing control circuit 38 for appropriately reading out the digital recording image signal written in the image memory section 2, and based on the read digital recording image signal. An LED driver circuit 39 for controlling light emission of the LED head 29, a lateral misalignment detection control circuit 40 for detecting lateral misalignment of the sheet 31 on which the toner image is transferred during transportation, and a controller 41 for controlling these are provided. Has been.

A fixing roller pair 42, which is a pair of pressing force variable conveyance rollers for conveying the paper 31 in a sandwiched state, is provided on the conveyance path along which the paper 31 on which the toner image is transferred is conveyed. The fixing roller pair 42 is provided so that the pressing force on both ends in the axial direction can be varied. Further, a line sensor 43 for reading one end side in the lateral width direction orthogonal to the transport direction of the transported sheet 31 and a light source 44 facing the line sensor 43 are provided. The line sensor 43 is connected to the lateral deviation detection control circuit 40.

The fixing roller pair 42 comprises a heating roller 42a and a pressure roller 42b, as shown in FIG.
The heating roller 42a is fixedly held by the bracket 45, and the pressure roller 42b is held by the bracket 45 so as to be movable in the direction of approaching and separating from the heating roller 42a. The heating roller 4 is attached to the pressure roller 42b.
A pair of left and right pressurizing force adjusting mechanisms 46 for increasing or decreasing the pressurizing force between the pressure roller 42a and the pressure roller 42b are connected to each other. The pressurizing force adjusting mechanisms 46 sequentially transmit the motor 47 and the rotation of the motor 47. The gears 48 to 50, the worm gear 51 connected to the gear 50, the bracket 52 that moves up and down by the rotation of the worm gear 51, and the bracket 53 attached to the central shafts of the bracket 52 and the pressure roller 42b.
A spring 54 stretched between the
And a photo interrupter 55 for detecting the ascending / descending position of. A fan 56 for cooling the motor 47 is provided near the pressurizing force adjusting mechanism 46.

Next, the structure of the lateral displacement detection control circuit 40 will be described with reference to the block diagram of FIG. The lateral shift detection control circuit 40 includes an amplifier 57 that amplifies the analog signal from the line sensor 43, an A / D converter 58 that converts the analog signal amplified by the amplifier 57 into a digital signal, and a converted digital signal. The signal is compared with predetermined binarization level data, and the comparison result is output as a binarization signal (“H” when there is paper, “L” when there is no paper) as shown in FIG. A comparator 59, a paper edge detection unit 60 that is a paper edge detection unit, a paper edge determination unit 61 that is a paper conveyance amount detection unit, a lateral deviation detection unit 62 that is a lateral deviation detection unit, a comparator 59 and a paper sheet. It is formed by a timing generation unit 63 that controls the operation timing of the edge detection unit 60 and the paper edge determination unit 61.

The paper edge detecting section 60 is provided with the comparator 59.
The edge position of the sheet 31 is detected based on the output from the.
The structure is, as shown in FIG. 7, an AND gate 64 to which an output (binarized signal) from a comparator 59 and a detection start signal described later are input, a read clock from the synchronization control circuit 13 and a read described later. A 12-bit counter 66 to which the output from the D flip-flop circuit 65, the AND gate 64, the read clock, and the output from the D flip-flop circuit 65 are input. Bit flip-flop circuit 6
It is formed by 7.

The sheet edge determining section 61 detects the amount of conveyance of the sheet 31 and, based on the sheet edge data for each predetermined plurality of lines detected by the sheet edge detecting section 60, the position of the sheet edge within the plurality of lines. Determine the data (reference position data, measurement position data). As shown in FIG. 9, the structure is formed by an AND gate 68, an OR gate 69, a D flip-flop circuit 70, a comparator 71, and D flip-flop circuits 72 and 73.

The lateral deviation detecting section 62 detects the lateral deviation amount and lateral deviation direction of the sheet from the reference position data and the measurement position data determined by the sheet edge determining section 61. As for the structure, as shown in FIG. 11, the position data (reference position data) of the sheet edge portion first determined by the sheet edge determination unit 61 and the position data (measurement position data) determined after the second time are compared. Formed by a comparator 74, a subtracter 75, 76 for calculating the difference between the reference position data and the measured position data, and a selector 77 for deciding which of the subtraction results obtained by the subtracters 75, 76 to be selected. There is.

Next, the schematic structure of the entire lateral deviation correction device will be described with reference to the block diagram of FIG. The lateral displacement detection control circuit 40 is connected to the control unit 41, which is a pressing force control unit that determines an increase / decrease amount of the pressing force by the pressing force adjustment mechanism 46 based on the detection result of the lateral displacement detection unit 62. There is. The control unit 41 has a CPU 78 that performs various processing operations and an RO that fixedly stores a control program.
M79, RAM8 for temporarily rewriting various information freely
0 and PIO (parallel input / output element) 81a, 81b
And the like. The lateral deviation detection control circuit 40 is connected to one PIO 81a, and the other PIO 81a is connected.
The pair of left and right motors 47 and photo interrupter 55 are connected to 81b.

Next, the schematic structure of the detection unit for the sheet 31 using the line sensor 43 will be described with reference to FIGS. 3 to 5. A light source 44 and a line sensor 43 are arranged so as to face each other across a conveyance path along which the sheet 31 is conveyed,
Further, a filter 44a having a honeycomb structure for correcting the light emitted from the light source 44 into substantially parallel light is provided on the light source 44 side. The filter 44a has a diameter of 1 ×
It is formed to have a height of 1 mm and a height of 20 mm. Therefore, the light passing through the filter 44a becomes a substantially parallel light with an inclination within 1/20. And filter 4
When the sheet 31 passes between the line sensor 4a and the line sensor 43, the line sensor 43 outputs analog signals of dark output and bright output as shown in FIG.

The sheet 31 to be conveyed is the filter 4
4a and the line sensor 43 are displaced in the vertical direction, but when the dimension between the filter 44a and the line sensor 43 is about 3 mm, the paper 31 is at the upper position (the filter 44).
a position) and lower position (position on the line sensor 43 side)
When passing through and, as shown in FIG. 5, 3 mm × 1
A reading error of /20=0.15 mm occurs. If the line sensor 43 has 8 pixels per 1 mm and the maximum reading width is 256 mm, the total number of images is 2048 pixels and 0.125 mm per pixel, so the reading error is about 1 pixel. It is well within the tolerance.

An outline of the lateral deviation detection operation of the sheet 31 in such a configuration will be described with reference to the timing chart of FIG. First, when a sensor (not shown) detects that the paper 31 is conveyed to above the line sensor 43,
The detection result is input to the control unit 41, and the detection start signal from the control unit 41 becomes “H”. Detection start signal is "H"
Then, the timing generation unit 63 outputs a sample signal which becomes “H” every predetermined period (for example, 1 second). Further, the reading start signal for the line sensor 43 is 1
It is output from the timing generation unit 63 every / 64 seconds. Therefore, the edge of the sheet 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 61 is set as the reference position data, and hereinafter, the sample signal becomes “H”. The position data determined by the paper edge determination unit 61 each time it becomes H ″ is used as the measurement position data. Further, the lateral deviation detecting unit 62 detects the lateral deviation amount and the lateral deviation direction of the sheet 31 based on the reference position data and the measurement position data.

Next, the operation of paper edge detection in the paper edge detection unit 60 will be described with reference to the timing chart of FIG. For the structure of the paper edge detection unit 60, refer to FIG. When the detection start signal is output from the control unit 41, the timing generation unit 63 outputs a read start signal in synchronization with the read clock to the line sensor 43 at a predetermined cycle, and the reading of the end portion of the paper 31 is started. Then, the comparator 59 outputs a binarized signal based on the read data from the line sensor 43. Then, the detection start signal and the comparator 5
The signal (signal) when the binarized signal output from 9 is input to the AND gate 64 is input to the count enable terminal of the counter 66, and the sheet 31 is detected (the output of the comparator 59). Is "H"), the counter counts up in synchronization with the read clock.

Prior to this count-up operation,
The read start signal is read by the D flip-flop circuit 65, and the signal (signal) which is latched and inverted for one clock of the read clock is input to the clear terminal of the counter 66, so that the outputs Q1 to Q11 are cleared in advance. .

The flip-flop circuit 67 latches the output of the counter 66 at the next rising of the reading start signal, and outputs it to the paper edge determination unit 61 as the position data of the paper edge of the current line. Then, this processing is continued until the detection start signal becomes "L" and the detection is completed.

The counter 66 and the flip-flop circuit 67 have 12 bits because the line sensor 43 has 2048 pixels. Line sensor 4
If the number of pixels of 3 changes, this bit configuration also changes, so that the counter 66 and the flip-flop circuit 67 have 12 bits.
It is not limited to bits.

Next, the operation of the paper edge determination unit 61 for determining the paper edge will be described with reference to the timing chart of FIG. For the structure of the paper edge determining unit 61, refer to FIG. When the detection start signal is output from the control unit 41 and the data of the paper end portion output from the paper end detection unit 60 is detected in synchronization with the reading start signal, the D flip-flop circuit 70 of the D flip-flop circuit 70 is operated via the OR gate 69. The first latch signal is input to the clock terminal, and the data at the edge of the paper at that time is D
The maximum value data is latched by the flip-flop circuit 70 (point A). The comparator 71 compares the maximum value data latched by the D flip-flop circuit 70 with the data at the edge of the sheet obtained thereafter. Then, when (maximum value data) <(paper edge portion data), the signal from the comparator 71 becomes “H”, and the AND gate 68.
At AND, the maximum value latch signal is ANDed, and the value is input to the clock terminal of the D flip-flop circuit 70 via the OR gate 69 to update the maximum value data (point B).

By detecting the maximum value data over a predetermined section (a plurality of lines), the conveyance amount of the sheet 31 is detected, and after the detection, the first D flip-flop after the detection is started. The maximum value data is latched by the reference position latch signal in the switching circuit 72, and is output to the lateral deviation detection unit 62 as reference position data.

Next, the operation of the lateral deviation detection unit 62 for lateral deviation detection will be described with reference to the timing chart of FIG. Note that FIG. 11 is referred to for the structure of the lateral deviation detection unit 62. When the detection start signal is output from the control unit 41 and the sample signal is generated from the timing generation unit 63, the paper edge determination unit 61 determines the reference position data (for example, 30) by the first sample signal. Is output to the lateral deviation detection unit 62. Then, every time the sample signal is generated for the second time, the third time, or the like, the paper edge determination unit 61 outputs the measurement position data. And
The reference position data and the measured position data are compared by the comparator 7
In step 4, the magnitude is determined, and if (reference position data) <(measurement position data), an “H” signal is output, and in other cases, an “L” signal is output (signal).

At the same time, the subtracter 75 calculates (reference position data)-(measurement position data), and the subtractor 76 calculates (measurement position data)-(reference position data). Is output to the selector 77 (signal,). Then, of the calculation results of the subtracters 75 and 76, depending on the comparison result of the comparator 74, if (reference position data) <(measurement position data), the subtracter 76
Of the horizontal shift amount (shift amount data), the calculation result of the subtracter 75 is used as the horizontal shift amount data (shift amount data) otherwise.
Output to 1.

Furthermore, the magnitude relation between the reference position data and the measured position data determined by the comparator 74 is output to the control unit 41 as data indicating the lateral shift direction (shift direction data). Specifically, when the paper 31 shifts to the right, the measurement position data increases, so when the output of the comparator 74 is "H", it is on the right, and when the output of the comparator 74 is "L", it is on the left. 31 indicates that it is displaced. FIG. 13 shows paper 3
FIG. 1 is a conceptual diagram showing a case where 1 has a lateral displacement to the left.

Next, the principle of lateral displacement correction by the pressing force adjusting mechanism 46 when the sheet 31 is laterally displaced will be described with reference to FIG. In a normal state in which the sheet 31 is not laterally displaced, the heating roller 42a and the pressure roller 42b
The pressing force between and is adjusted so as to be constant over the entire length in the longitudinal direction, and as shown in FIG.
The outer peripheral surface of the heating roller 42a is slightly crushed. When the pressing force between the heating roller 42a and the pressing roller 42b is increased by the pressing force adjusting mechanism 46, as shown in FIG.
As shown in (b), the outer peripheral surface of the heating roller 42a made of a soft material is largely crushed. The radius of the heating roller 42a at the point (point a) intersecting the straight line connecting the center of the heating roller 42a and the center of the pressure roller 42b is R _{1 in} the case of FIG. 19A,
In the case of FIG. 19B, it becomes R ₂ , and the magnitude relation is R.
₁ > R ₂ . On the other hand, since the angular velocity ω of the heating roller 42a does not change, the relationship between the velocities V ₁ and V _{2 at} the point a is V ₁
= R ₁ × ω, V ₂ = R ₂ × ω, and V ₁ > V ₂ . Therefore, when the pressing force is changed along the longitudinal direction of the fixing roller pair 42, the conveying speed becomes slower on the side where the pressing force is stronger and on the side where the pressing force is weaker.

Therefore, when the sheet 31 is laterally displaced to the left as shown in FIG. 20, the pressing force on the right end side of the fixing roller pair 42 is made stronger than that on the left end side to act on the right side of the sheet 31. The conveyance speed becomes slower, and the sheet 31 comes closer to the right side where the conveyance speed is slow (the pressure is strong), and as a result, the lateral deviation of the sheet 31 that has been laterally displaced to the left is corrected. The difference in pressure between the left end side and the right end side of the fixing roller pair 42 is adjusted according to the lateral deviation amount of the sheet 31, and when the lateral deviation amount is large, the difference in pressing force between both end sides is increased. When the amount of lateral deviation is small, the difference between the pressing forces on both ends is reduced.

Next, a series of operations for correcting the lateral deviation of the sheet 31 will be described with reference to the flowchart of FIG. The control unit 41 determines whether the paper 31 is passing between the line sensor 43 and the light source 44 based on the detection result of the sensor,
If it is passing, the sensor is turned on (step 1).
When the sensor detects the sheet 31 and is turned on, a detection start signal for starting the lateral deviation detection of the sheet 31 is output from the control unit 41 (step 2), and the lateral deviation detection unit 62 illustrated in FIG.
At, the lateral deviation amount and the lateral deviation direction are detected (step 3).

Next, the control unit 41 determines whether or not the detected lateral deviation amount is greater than or equal to the set amount (step 4). If the detected lateral deviation amount is greater than or equal to the set amount, it is increased in accordance with the lateral deviation amount. The pressing force is determined by the control unit 41 (step 5). When the lateral deviation amount is less than or equal to the set amount, it is determined whether or not the detection of the paper 31 is completed (step 6). When the detection of the paper 31 is completed, the pressing force of the fixing roller pair 42 is determined. Is returned to the initial value (step 7), and the lateral deviation correction operation ends. On the other hand, when the detection of the paper 31 is not completed, the process returns to step 3 and the detection of the lateral deviation amount and the lateral deviation direction is continued.

When the pressing force to be increased is determined in step 5, the correction direction at the time of performing the lateral deviation correction is based on the deviation direction data from the lateral deviation detection section 62 and the control section 4
It is determined in step 1 (step 8). When the lateral displacement is leftward, the pressing force adjusting mechanism 46 corrects the sheet 31 to the right by increasing the pressing force on the right end side of the fixing roller pair 42, and the lateral displacement is rightward. In the case of occurrence of, the pressing force adjusting mechanism 46 increases the pressing force on the left end side of the fixing roller pair 42 to correct the sheet 31 to the left (step 9). After these corrections are made, it is determined whether or not the detection of the paper 31 is completed as described above (step 6). When the detection of the paper 31 is completed, the pressing force of the fixing roller pair 42 is returned to the initial value (step 7), and the lateral deviation correction operation is completed. When the detection of the paper 31 is not completed, the process returns to step 3 and the detection of the lateral deviation amount and the lateral deviation direction is continued.

[0040]

According to the first aspect of the present invention, the edge position of the sheet being conveyed on the conveying path in the width direction orthogonal to the conveying direction is detected by the sheet edge detecting means, and the sheet is conveyed. The amount of paper conveyance amount detection means detects the amount, and the lateral deviation amount and the lateral deviation direction of the paper are detected by the lateral deviation detection means based on the detection results of these detection means. Even if the lateral deviation starts after passing the detection point, the lateral deviation can be detected. When the lateral deviation is detected, the pressing force on at least one end side of the pair of pressing force variable conveyance rollers for conveying the paper is detected. By making adjustments based on the detection result of the lateral displacement detection means, a difference is generated in the pressure force on both ends of the pressure force variable conveyance roller pair,
It is possible to correct the lateral misalignment when the laterally misaligned sheet is nipped and conveyed by the pair of pressing force variable conveyance rollers.

According to the second aspect of the present invention, since the fixing roller pair is the pressing force variable conveyance roller pair, it is possible to correct the lateral deviation of the sheet at the time of fixing, and therefore, the lateral deviation remains as it is. By continuing fixing to the paper, it is possible to prevent wrinkles from forming on the paper, and it is possible to weaken the pressure applied to the fixing roller pair as necessary even at the time other than lateral misalignment correction, For example, when a paper jam occurs between the pair of fixing rollers, the jam processing can be easily performed by weakening the pressing force.

[Brief description of drawings]

FIG. 1 is a block diagram showing a structure of a lateral deviation detection control circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic structure of the entire lateral deviation correction device.

FIG. 3 is a front view showing a schematic structure of a reading unit that reads a sheet.

FIG. 4 is an explanatory diagram showing a positional relationship between a line sensor and a sheet, an analog signal output from the line sensor, and a binarized signal converted from the analog signal.

FIG. 5 is an explanatory diagram of a reading error that occurs when a conveyed sheet is vertically displaced between a filter and a line sensor.

FIG. 6 is a timing chart showing an outline of lateral deviation detection of a sheet.

FIG. 7 is a block diagram showing a structure of a paper edge detection unit.

FIG. 8 is a timing chart of sheet edge detection.

FIG. 9 is a block diagram showing a structure of a paper edge determination unit.

FIG. 10 is a timing chart for determining a sheet edge.

FIG. 11 is a block diagram showing a structure of a lateral deviation detection unit.

FIG. 12 is a timing chart for lateral deviation detection.

FIG. 13 is a plan view showing a state in which a sheet is laterally displaced to the left.

FIG. 14 is a block diagram showing a schematic structure of the entire digital copying machine.

FIG. 15 is a vertical cross-sectional front view showing a schematic structure of a document reading device.

FIG. 16 is a plan view showing an arrangement state of keys on the operation panel.

FIG. 17 is a vertical sectional front view showing the schematic structure of the copying apparatus.

FIG. 18 is a front view showing a pressing force adjusting mechanism.

FIG. 19 is an explanatory diagram showing the principle of lateral misalignment correction, in which (a) is a state in which the pressing force between the heating roller and the pressure roller is weak,
(B) is a state in which the pressing force between the heating roller and the pressure roller is increased.

FIG. 20 is a plan view illustrating a state where lateral deviation correction is being performed.

FIG. 21 is a flowchart showing a series of operations for lateral deviation correction.

[Explanation of symbols]

31 paper sheet 41 pressing force control means, pressing force correction means 42 pressing force variable conveying roller pair, fixing roller pair 46 pressing force adjusting mechanism 60 sheet edge detecting means 61 sheet conveying amount detecting means 62 lateral deviation detecting means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 15/00 516 G03G 15/00 516 15/20 102 15/20 102 (72) Inventor Tatsuhiko Okada 713 Tsuruga Sone, Yashio City, Saitama Prefecture Ricoh Yu-Techno Co., Ltd.

Claims (2)

[Claims] 1. A sheet edge detecting unit for detecting an end position of a sheet being conveyed on a conveying path in a lateral width direction orthogonal to a conveying direction, and a sheet conveying amount detecting unit for detecting a conveying amount of the sheet. Lateral deviation detecting means for detecting the lateral deviation amount and lateral deviation direction of the paper being conveyed based on the detection results of the paper edge detecting means and the paper conveyance amount detecting means, and conveying the paper in a sandwiched state. A pair of pressing force variable conveying rollers whose pressing force on both ends in the axial direction is variable, a pressing force adjusting mechanism for increasing or decreasing the pressing force of at least one end side of the pressing force variable conveying roller pair, and the lateral deviation detecting means. A lateral deviation correcting device for a sheet, comprising: a pressing force control means for determining an increase / decrease amount of the pressing force by the pressing force adjusting mechanism based on a detection result. 2. The sheet lateral misalignment correction device according to claim 1, wherein the pair of pressurizing force conveying rollers is a fixing roller pair.