JPS6227267A - Original skew feed correcting device for copying machine - Google Patents

Abstract

PURPOSE:To effectively correct the quantity corresponding to the skew quantity by selectively controlling multiple pairs of drive members in response to the skew quantity on a sheet original conveying path. CONSTITUTION:When a holding member 53 is rotated centering a supporting bar 51 by the operation of either one of the first and second solenoid 67, 68, one side of a conveying path 59 is moved to the lower position from the neutral position against the supporting bar 51, and the other side is moved to the upper side. At this time, the lowered side portion of the conveying path 59 is communicated to conveying paths 82, 85 almost linearly, and as a result, the portion of a sheet original A passing this position passes the conveying path 59 at the shortest distance. The lifted side portion of the conveying path 59 is further bent upward, and as a result, the portion of the sheet original A passing this position passes the conveying path 59 at the longer distance than at the neutral position. Accordingly, the sheet original A passing the conveying path 59 has different conveyance distances at both sides and is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a skew-feed correction device for originals conveyed through the circulation path of a copying machine, which performs slit exposure by circulating sheet originals through the sheet original circulation path.

The document fed from the long-end pinch document feeding section is introduced into a loop-shaped circulation path, and is circulated for a preset number of copies. Copying machines are known in which a photoreceptor is exposed to light through an aperture system while sliding a glass surface, the required number of copies are made, and the original is ejected to an original tray after completing circulation a predetermined number of times. ing. In this type of copying machine, if the document is skewed due to the condition of the conveyance path, the skew of the document will accumulate during repeated circular conveyance, resulting in copies or images that are skewed to the paper. Since a copy may be made with a portion missing, it is necessary to detect and correct the skew feeding (hereinafter referred to as skew) every cycle.

Various skew correction devices have been used and proposed in the past. For example, there is a known method for correcting paper skew by tilting the axis of a conveyance roller provided in the paper conveyance path with respect to the conveyance direction, but this method causes roller wear and roller surface slippage. The amount of correction tends to change, and it is difficult to appropriately change the correction value in response to the skew.

Furthermore, Japanese Patent Laid-Open No. 57-93848 discloses a skew feed correction device as shown in FIGS. 1 and 2. To briefly explain this, as shown in FIG.
1 is conveyed in a skewed manner, there will be a lag in the detection time of the document by the skew detection sensors 202 and 203. If the skew time is longer than the required time, the sensor 20
When sensor 2 detects a document, the solenoid 204 is activated, and conversely, when the sensor 203 detects a document first, the solenoid 205 is activated to move the correction member 206 counterclockwise or clockwise with the point P as the fulcrum. The document 201 is tilted by an angle α, and as shown in FIG. 2, the original 201 is guided by the reversing guide surface 208 of the guide member 207 to correct the skew when reversing.

However, since the correction member is tilted by a fixed angle α regardless of the amount of skew, the correction may be insufficient or overcorrected, making it difficult to correct the document appropriately according to the amount of skew. Since the tilting angle α of the correction member is constant regardless of the width of the document, the amount of correction for a document with a small width is smaller than that of a document with a large width. If the skew cannot be corrected properly, and if the skew amount exceeds a predetermined amount, the skew cannot be corrected completely and copies are made as they are, resulting in unnecessary copies with missing images. there were.

Further, as the document becomes longer, the amount of skew correction by the guide member 207 increases, and conversely, as the document becomes shorter, the amount of correction decreases. Therefore, like an original circulation type copying machine, it has a lower conveyance path and an upper conveyance path communicating with each other, and the upper conveyance path is provided with a plurality of guide members that appear and retract to circulate the original to the lower conveyance path. Due to the operation of
In a copying machine in which a single original is repeatedly conveyed through the side strip feed path and multiple copies are made from the same original, long originals are circulated multiple times. Since the amount of skew correction is large each time, the amount of skew correction is too large, resulting in skew in the opposite direction.For short documents, the amount of skew correction is small each time, so the amount of skew gradually increases. This method has the disadvantage that the final result is that the image is missing, resulting in unnecessary copying.

Purpose The present invention eliminates the above-mentioned drawbacks of the conventionally implemented and proposed document skew correction devices for copying machines, especially the problems when applied to a copying machine that carries out copying by circulating a document multiple times. An object of the present invention is to provide a document skew correction device capable of correcting an amount corresponding to the skew amount.

In order to achieve the above object, the present invention provides a method in which a pair of curved guide plates facing each other at a distance and forming a document conveyance path between their opposing surfaces are tilted about the center line of the width of the conveyance path. a correction conveyance member which is preferably disposed in the document circulation path; the correction conveyance member is attached to a base plate that pivotally supports the correction conveyance member in a tiltable manner as described above; a plurality of pairs of drive members provided at equal distances from each other, a sensor provided on both sides of the center line of the transport path on the upstream side of the correction transport member in the transport direction to detect the leading edge of the sheet document, and a detection signal from the sensor. The present invention is characterized in that it has a comparison means for comparing this with a preset detection level, and selectively controls the plurality of pairs of driving members described above in accordance with the amount of skew in the sheet document conveyance path.

The present invention will be described below based on embodiments shown in the drawings.

First, the skinny correction mechanism, which is novel in itself, used in this invention will be explained. In FIGS. 3 to 5, a pair of side plates 71 fixed to the main body of the copying machine are shown.
A support rod 51 is established approximately at the center of the beam-shaped support member 52 stretched between the two, and approximately the center of the holding member 53 is rotatably supported by the support rod 51 via a bearing 54. Arc-shaped inner and outer guide plates 56 and 57 are attached to the document conveyance path side of the holding member 53 by a bracket 58 so as to form a conveyance path 59 at a predetermined interval. The position in the thrust direction is determined by a collar 55.

As shown in FIG. 5, two sets of support members each having a pair of front and rear brackets 62 and 62' are located near both ends of the support member 52 and away from the back surface of the holding member 53, and are attached to the support rod 51. Installed in symmetrical positions on both sides. The pressing member 63 is slidably fitted into the through hole provided in the bracket 62, 62'.
A compression spring 65 is interposed between the flange 64 attached to the inside of the bracket 62' and the inner surface of the bracket 62', so that the head of the suppressing member 63 is always pressed against the back surface of the holding member 53, unless an external force is applied. , the holding member 53 is attached to the support rod 5
1, hold them at equal positions on the left and right sides.

A pair of solenoids 6 are connected via brackets 72 to substantially symmetrical positions on both sides of the support rod 51 of the support member 52.
7 and 68 are installed.

The operating rods of these solenoids 67 and 68 are attached to the holding member 53.
The holding member 53 is connected to an arm 66 attached to the support rod 51 to rotate the holding member 53 about the support rod 51 as the operating rods of the solenoids 67 and 68 protrude.

Next, based on FIGS. 6 to 8, the guide plates 56 and 5
7 will be explained in more detail.

A curved conveyance path 5 formed between guide plates 56 and 57
9 is a conveyance path 82 between guide plates 80 and 81 fixed in the copying machine main body and a conveyance path 85 between guide plates 83 and 84.
The sheet document A, which has been conveyed through the conveyance path 82 by the conveyance roller section, is always fed to the conveyance path 85 through the conveyance path 59 .

The conveyance path 59 is kept in an equilibrium state (
When in the neutral position, it is positioned slightly above the conveyance path 82°85 (Fig. 6), and the sheet document A fed from the conveyance path 82 is conveyed while curving upward. It passes through road 59. Next, the first. 2nd solenoid 6
When the holding member 53 is rotated around the support rod 51 by the operation of either one of 7.68, one side of the conveyance path 59 with respect to the support rod 51 moves from the neutral position to the lower position (7th position).
(Fig. 8) and the other side moves to the upper position (Fig. 8). At this time, the portion of the conveyance path 59 on the lowered side is the seventh
As can be seen from the figure, it communicates with the transport paths 82 and 85 in a substantially straight line, and as a result, the portion of the sheet I-original A that passes through this position passes through the transport path 59 in the shortest distance. That will happen. Also, the portion of the conveyance path 59 on the elevated side.

As can be seen from Figure 8, it will be further curved upwards, so that the part of the sheet document A that passes through this position will pass through an even longer distance than in the neutral position (Figure 6). , will pass through the transport path 59. Therefore, when one of the solenoids 67 and 68 is activated and the holding member 53 is rotated, the sheet document A that passes through the conveyance path 59 will be conveyed for a different distance on both sides.

Next, the skew correction operation in the above correction device will be explained. As shown in FIG. 9, the skew of the document A is detected by the first and second sensors 31 and 32, and as shown by the solid line in FIG. 3 or the chain line in FIG. When the document A is conveyed, the second sensor 32 detects the leading edge of the document A before the first sensor 31 does, and this sensor 3
The second solenoid 68 corresponding to No. 2 is activated. Then, the holding member 53 rotates and the second solenoid 68 side is lifted, and the right conveyance path 59 in FIG. 3 is set to the state shown in FIG. 8, and the left conveyance path 59 is set to the state shown in FIG. 7. As a result, when the original A passes through the conveyance path 59, the skewed end on the leading sensor 32 side passes a longer distance than the opposite end on the trailing sensor 31 side, so that the original A passes through the transport path 59. Due to the difference in conveyance distance between both ends of A,
When the document A is fed to the conveyance path 85, the skew will be corrected. If the document A is skewed to the opposite side, the skew is similarly corrected by the operation of the sensor 31 and the first solenoid 67. 1st
FIG. 0 shows an example of a control circuit that controls the skew correction section 23. In the skew detection section 22, the first . The second sensors 31 and 32 are composed of light emitting diodes 31a and 32a and phototransistors 31b and 32b. When the light emitted from the light emitting diodes 31a and 32a is reflected by the original, the phototransistors 31b and 32b are turned on, and an H level signal is output from the comparators 161 and 162, and the signal is transmitted through the amplifiers 171 and 172. Input port I- of the microcomputer 180, respectively.
2.

The microcomputer 180 has a built-in clock pulse generator, first and second counters, first and second drive signal generators, and a comparator, as shown in FIG. When the document is detected, the first counter operates to count the number of clock pulses output from the clock pulse generator, and when the second sensor 32 detects the document, the counting is stopped, and the first counter starts counting the number of clock pulses output from the clock pulse generator. is output as the first count signal. On the contrary, sensor 3
When sensor 2 detects a document for the first time, the second counter operates and counts the number of clock pulses, and when the first sensor 31 detects the document, it stops counting, and the second counter uses the counted number as a second count signal. Output.

Next, the operation of the above embodiment will be explained.

When the original A is skewed and conveyed as shown in FIG. 9, the second sensor 32 first detects the original A, and in FIG. input boat I-
Enter 2. The second counter counts the number of clock pulses output from the clock pulse generator.
detects document A (tz in FIG. 12), it stops counting, and this causes the second counter to input a second count signal to the second drive signal generator, which in turn inputs the second count signal to the second drive signal generator. Output the corresponding second drive signal to port P-
2 to operate the second renoid 68, and the first
As shown in FIG. 3, the skew correction section is rotated clockwise by an angle α.

If the document A is skewed and conveyed in the opposite direction to that shown in the figure, the first sensor 31 may detect the document first.
3) An H level signal is output from the comparator 161, and the input port I-1 of the microcomputer 180 is output.
Enter. Then, the first counter does the same as above,
The number of clock pulses is counted and when the second sensor 32 detects the document A (t4 in FIG. 12), the counter is stopped. As a result, the first counter inputs the first count signal to the first drive signal generator, and the first drive signal generator outputs the corresponding first drive signal to the output port P-.
1 and operates the first solenoid 67 to rotate the skew correction section counterclockwise in FIG.

FIG. 20 shows another example of a control circuit for controlling the skew correction unit 23, in which each skew sensor 31 to 34 includes a light emitting diode 31a to 34a and a phototransistor 31b.
34b, and light emitting diodes 31a to 34a.
When the light emitted from the original is reflected by the original, photo 1
~The transistors 31b to 34b are turned on, and L level signals are output from the comparators 161 to 164.
Microcomputer 1 via amplifiers 171 to 174
It is designed to input to 80 input ports ■.

The microcomputer 180 has a built-in clock pulse generator (not shown) and first and second counters, and when the skew sensors 31 and 33 first detect a document, the first counter operates to generate the clock pulse. The number of clock pulses output from the device is counted, and when the skew sensors 32 and 34 detect a document, the counting is stopped.

Conversely, when the skew sensors 32, 34 first detect a document, a second counter is activated to count the number of clock pulses, and stops counting when the skew sensors 31, 33 detect a document.

When the original is large in size and the skew sensor 31 detects the original for the first time, the count l-number of the first counter is compared with the first and second preset numbers, and the counted number is the first, If it is between the second set number, the output port P-
A drive signal is output from output port P-2 when the number is equal to or greater than the second set number. On the other hand, when the skew sensor 32 detects the document for the first time, the count number of the second counter is compared with the preset first and second set numbers, and the count number is compared with the first and second set numbers. If the number is between, the drive signal is output from the output port P-4, and if the number is equal to or greater than the second set number, the drive signal is output from the output port P-3.

When the original is small in size and the skew sensor 33 detects the original for the first time, the count number of the first counter is set to the preset third. When compared with the fourth set number, if the counted number is between the third and fourth set numbers, the drive signal is output from the output port P-1, and if it is equal to or greater than the fourth set number, the drive signal is output from the output port P-1. A drive signal is output from 2. On the other hand, when the skew sensor 34 detects the document for the first time, the count number of the second counter is compared with the third and fourth set numbers set in advance.
That count number is the third. When the number is between the fourth set number, the drive signal is output from the output port P-4, and when the number is equal to or greater than the fourth set number, the drive signal is output from the output port P-3.

And the output port P-1 of the microcomputer 180
, 2, 3, and 4 are output from the solenoid 67.
．． 69,70.68 is activated.

Next, the operation of the embodiment constructed as described above will be explained.

When the original A is conveyed in a skewed manner as shown in FIG. Enter 4. A second built-in counter in the microcomputer 180 counts the number of clock pulses outputted from a built-in clock pulse generator (not shown) (step t in FIG. 21). When the document A is further conveyed and the skew sensor 31 detects the document A, the count stops (tz in FIG. 21), and the count number of the second counter is compared with the preset first and second set numbers. If the count number is between the first and second set numbers, a drive signal is output from output port P-4, and solenoid 6 is activated.
8 to tilt the skew corrector 23 clockwise by an angle α using the support rod 51 as a fulcrum, as shown in FIG. 3 outputs a drive signal, operates the solenoid 70, and tilts the skew correction section 23 clockwise by an angle β.

When the document A is skewed and conveyed in the opposite direction to that shown in the figure, the skew sensor 31 first detects the document (t3 in FIG. 21), the comparator 161 outputs an H level signal, and the microcomputer 181 input to input port I-1 of. and microcomputer 1
80 has the built-in first counter in the same manner as above,
The number of clock pulses is counted until the skew sensor 32 detects the document A (see 4 in FIG. 21), and the counted number is compared with the preset first and second set numbers, and the counted number is determined as the first set number. ．． If it is between the second set number, the output port P
-1 outputs a drive signal, and if the number is equal to or greater than the second set number, outputs a drive signal from output port P-2, and solenoid 67
．． 69 to tilt the skew correction section 23 counterclockwise at angles α and β.

When a small-sized original A' is conveyed in a skewed manner as shown in FIG. -3. Then, the built-in second counter of the microcomputer 180 counts the number of clock pulses in the same manner as described above until the skew sensor 33 detects the document A'. and the preset third and fourth set numbers, and if the count is between the third and fourth set numbers, output a drive signal from the output boat P-4; For example, a drive signal is output from the output boat P-3, and the skew correction section 23 is tilted clockwise by angles α and β (see FIG. 22) in the same manner as described above.

When the document A' is conveyed with a skew in the opposite direction to that shown in the drawing, the skew sensor 33 first detects the document A', and in the same way as above, the first counter and the skew sensor 34 detect the document A'. t7 to ts in Figure 21) Compare the counted number with the third and fourth set numbers set in advance, and if the counted number is between the third and fourth set numbers, output Output a drive signal from boat P-1, and if it is equal to or greater than the fourth set number, output boat P-2
A drive signal is outputted from the skew correction section 23, and the skew correction section 23 is tilted counterclockwise at angles α and β in the same manner as described above.

FIGS. 14 and 15 show an example in which the above-described skew correction device is installed in an original circulation copying machine 131.

In such copiers that make many copies of a single original, the same original is circulated through the same original transport path many times, so even if the original is straight, the skew gradually increases. go.

In FIG. 14, 132 is a document insertion opening, 134 is a barrier that abuts against the leading edge of the document that rises from the document insertion port 132 and is fed into the transport unit 133, and 137 and 138 are a pair of friction units that can be moved toward and away from each other by a solenoid 136. It's Laura.

As shown in FIG. 15, 135 is a width sensor consisting of four sensors 201 to 208 installed at a predetermined interval on each side of the center line of the conveying path in a direction perpendicular to the conveying direction of the lower conveying path. When any one of the sensors 201 to 208 detects a document, the solenoid 136 is activated, and the friction rollers 137 and 138 grip the document without skew. 139 is a solenoid that is activated by the delayed output of the solenoid 136 to remove the barrier 134 from the conveyance path; 145 is a sensor that measures the length of the document;
As shown in FIG. 17, it is installed on the center line of the conveyance path, and the length detection sensor 145 and width sensor 135 detect seven different document sizes.

Solenoid due to the delayed output from solenoid 136],
39 causes the barrier 134 to be removed from the conveyance path, and the roller 138 begins to rotate, thereby starting to convey the document.

Reference numerals 1 and 40 denote transport rollers, and 141 a slit exposure section, through which an electrostatic latent image is formed on a photoreceptor drum (not shown) when an original passes therethrough.

Reference numerals 143 to 147 denote guide members 1 that protrude into the conveyance path and guide the original to each reversing conveyance path formed by the conveyance roller 140 and the like.
Reference numerals 43' to 147' designate solenoids for protruding the respective guide members 143 to 147, 142 a reversing guide plate for reversing the document, and 148 a paper discharge tray. When a document is inserted into the document insertion slot 132, the document is detected by the sensors 201 to 208 of the eleven sensors 135 shown in FIG. For example, if document A is A4 size, sensors 204 and 205 detect the document, and detection signals are input to macrocomputer 180 via amplifiers 170 and 171.

When the document A is conveyed, the length sensor 29 shown in FIG. 16 detects the document, and a detection signal is input to the microcomputer 180 via the amplifier 175.

In the microcomputer 180, a built-in counter (not shown) counts the number of clock pulses output from a built-in clock pulse generator (not shown) during the detection period, and this count number The document size is determined from the detection signals from the sensors 201 to 208.

When making multiple copies, if the document size is A4, for example, the microcomputer 180 outputs a drive signal from the A4 output boat, activates the solenoid 144', causes the guide member 144 to protrude into the conveyance path, and conveys the document. Form a loop.

If the document has a different size, guide members 143 to 147 corresponding to the size are projected. Then, the original is circulated through the formed transport loop, and each time it passes through the slit exposure section 141, a copy is made, thereby creating a predetermined number of copies.

Further, transfer paper for copying is fed from a paper feed tray (not shown) in synchronization with the conveyance of the original based on information from the original, and selected based on the copying magnification and the like.

After a predetermined number of copies have been repeatedly copied, the guide members 143 to 147 protruding into the conveyance path are released and the originals are discharged onto the paper discharge table 148.

The device 23 for correcting the skew of the document circulated through the document circulation path is installed in the conveyance path between the reversing conveyance path 142 and the guide member 143, which the document passes through in any of the conveyance loops from the shortest loop to the longest loop. It is being

(Hereinafter, blank space) In front of the skew correction device 23, as shown in Fig.
is provided on a straight line perpendicular to the conveyance direction, and the skew amount is detected by the sensor 33.34 when the original is small in size, and by the sensor 31.32 when the original is large in size.

As shown in FIG. 20, the skew amount detection sensors 3J to 3
4 inputs a signal to the CPU 180.

As shown in FIG. 21, the skew amount is determined by the signal from the skew amount detection sensor input to the CPU 180.

First, in the case of a dog-sized document, the amount of deviation in time (or distance) between the signals of the left and right skew amount detection sensors 31 and 32 is measured using a reference clock pulse (or an encoder pulse matched to the distance of the document). However, the amount of skew is determined by how many pulses there are. Naturally, the finer (shorter) the reference clock pulse (or encoder pulse), the more sensitive the skew amount detection becomes.

Similarly, in the case of a small size, the amount of time (or distance) deviation between the signals of the left and right skew amount detection sensors 33 and 34 is determined in the same manner as described above.

As shown in FIG. 22, the skew correction device consists of left and right solenoids 67 to 70, and an inner solenoid 69.
．． When solenoid 70 is activated, it tilts α around the fulcrum 51, and when the outer solenoids 67 and 68 operate, it tilts β around the fulcrum 51. With the slope of α, the amount of skew correction becomes y,
The amount of skew correction is X based on the slope of β. Further, the amount of correction is X>y.

FIG. 23 shows a flow chart of the skew amount and the operational relationship of the skew correction solenoid.

First, it is determined whether or not the document has entered the skew sensors (31 to 34), and if it has not entered, a different process is performed, and if it has entered, it is determined whether or not it has entered the right skew sensor (34, 32).

When a document enters the right skew sensor, a flag is set (ON) and it is determined whether a document enters the left skew sensor.

The amount of skew of the document is until the document enters the skew sensor on the left. During that time, each time a reference clock pulse (or encoder pulse) is input by a clock interrupt, the clock interrupt flow is processed once. Enter and increase the skew data by +1.

When a document enters the left skew sensor, skew data (here, the number of reference clock pulses or the number of encoder pulses) during that time is entered.

If the skew data is greater than or equal to X, that is, if the skew correction device is greater than or equal to the correction amount X (inclination β), the skew is corrected by tilting the correction device β. To tilt β, turn on correction 5QL68. At that time, FLAG
○FF I.

If the skew data is less than X and less than y,
The correction device is tilted α (correction 5QL70 is turned on), the skew is corrected, and FLAGI is OF I”.

If the skew data is smaller than y, the solenoid is not activated, FLAGl is set to 0FFL, and the next process is performed.

Similarly, if there is no document in the right skew sensor (34, 32), the left skew sensor (31, 33)
), so set FLAGI (ON).
) The skew amount of the document is the amount until the document enters the right skew sensor, and as above, the skew data includes the number of reference clock pulses or the number of encoder pulses.

If the skew data is X or more, turn on 5OL67 and set the flag to 0FFL. If the skew data is less than
Turn on L67, set the flag to 0FFL, and if the skew data is smaller than y, set the flag to 0FFI without activating the solenoid, and perform the next process.

By performing the above operations, it becomes possible to correct the document according to the amount of skew.

Naturally, if the number of skew correction solenoids is increased, the correction will be finer in accordance with the amount of skew.

Effects As described above, according to the present invention, appropriate skew correction can be performed depending on the size of the sheet document to be copied and the amount of skew at the skew detection section.

[Brief explanation of the drawing]

1 and 2 are a plan view and a cross-sectional view, respectively, showing an example of a conventionally proposed paper skew correction device, and FIG. 3 is a plan view of a skew correction device according to an embodiment of the present invention, and FIGS. 5
The figures are sectional views taken along lines rV-rV and -■ in Fig. 3, Figs. 6 to 8 are explanatory diagrams explaining the action of the skew correction conveyance member according to the present invention, and Fig. 9 is a skew detection sensor. FIG. 10 is a circuit diagram showing an example of a control circuit that controls the skew correction section, FIG. 11 is a block diagram explaining the functions of the CPU, and FIG.
FIG. 2 is an example of a timing chart of each element of the control circuit, FIG. 13 is a schematic diagram explaining the action of the solenoid controlled by the control circuit, and FIG. 14 is a configuration of the document circulation section of the document circulation copying machine. 15 is a schematic diagram showing the document width detection means, FIG. 16 is a diagram explaining the document length detection means, and FIG. 17 is an embodiment of the present invention applied to this copying machine. FIG. 3 is a schematic diagram illustrating the arrangement and operation of a skew detection sensor for the skew correction device. FIG. 18 is a control block diagram thereof, FIG. 19 is a plan view of the skew correction device of the embodiment, FIG. 20 is a circuit diagram showing an example of a control circuit for controlling the skew correction section, and FIG.
The figure is an example of a timing chart of each element of the control circuit, Figure 22 is a schematic diagram explaining the action of the four solenoids controlled by the control circuit, and Figure 23 is a diagram showing how skew correction is performed according to the amount of skew. It is a flowchart showing the flow of operation. 23... Skew correction device 31.32, 33.34... Skew detection sensor 51
... Curved guide plate swing shaft 52 ... Board 56.57... Curved guide plate (correction conveyance member) 59
...Curved original conveyance path 67.68, 69.70...Drive member 180...C
PU (Detection level comparison, control means) 'Me. Figure 9[]-31[]"33 Figure 16

Claims (1)

[Claims] In a copying machine that exposes a sheet document to slit exposure while copying it through a sheet document circulation path, a skew-feed correction device for a document conveyed through the above-mentioned circulation path is provided with a document conveyance path that faces each other at a distance, and between the opposing surfaces. A correction conveyance member comprising a pair of curved guide plates forming a center line of the width of the conveyance path, which are arranged in the document circulation path so as to be tiltable about the width center line of the conveyance path; a plurality of pairs of driving members attached to a supporting substrate and provided equidistantly on both sides of the conveyance path center line so as to tilt the correction conveyance member; It has a sensor provided on both sides to detect the leading edge of the sheet document, and a comparison means that inputs the detection signal from the sensor and compares it with a preset detection level, depending on the amount of skew in the sheet document conveyance path. A document skew feeding correcting device characterized in that the plurality of pairs of drive members are selectively controlled by the user.