JPH0812135A - Sheet material carrying device and image forming device and image reader - Google Patents

Abstract

PURPOSE:To detect a sheet material in a short time even if any sheet material is carried by moving a detecting means to detect a means to adjust a posture and a position of the sheet material according to a maximum one and a minimum one in a size width of the sheet material housed in a cassette. CONSTITUTION:A pinion 4 to transmit motive power from a stepping motor is meshed with a rack 5a, and a photosensor 2 is arranged on the tip of a sensor moving member 5 movable in the arrow B direction. The size of a sheet material in a cassette is detected before a start button is pushed, and a maximum one and a minimum one in the axial directional size (a width) is found out among them. For example, in the case of A4 (a maximum width) and A4R (a minimum width), the photosensor 2 is moved to a position (a first HP) like {(a width of A4)-(a width of A4R)}divided by 2=1a=1b. Afterward, when a copy button is pushed, a sheet material complying with a document is fed from the cassette.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet material conveying apparatus and an image forming apparatus or image reading apparatus such as an electronic copying machine having the sheet material conveying apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming and image reading apparatus such as a copying machine, a printer, a scanner, etc., the posture and position of a recording material or a sheet material as an original are adjusted just before the image forming and reading section. A registration device is being used.

A conventional example will be described with reference to FIGS. 12 and 13 by taking an electronic copying machine equipped with a registration device as an example.

FIG. 13 is an explanatory view of a main part of a general electronic copying machine. In order to match the transfer timing between the toner image on the photosensitive drum 10 'and the sheet material 1'to which it is transferred,
Further, in order to prevent the skew of the sheet material 1 ', a pair of registration rollers 7'for conveying the sheet material 1'is provided.

In FIG. 13, the sheet material 1'is conveyed by the slip roller pair 40 ', passes through the guide portion 41', and is abutted against the nip of the registration roller pair 7 '.
After that, it is conveyed to the transfer guide 42 'by the registration roller pair 7'. At that time, the position of the sheet material 1'in the conveying direction is adjusted by the registration roller pair 7 '. Transfer guide 4
The toner image is transferred to the sheet material 1 ′ that has passed 2 ′ by the photosensitive drum 10 ′ and the transfer charger 11 ′.

The adjustment of the position in the carrying direction will be described in detail below.

The adjustment of the position of the sheet material in the conveying direction is performed in two ways, that is, the sheet material is slanted (skew) and a deviation (horizontal deviation) in a direction (axial direction) orthogonal to the sheet material conveying direction. To make adjustments.

In FIG. 13, the sheet material 1'abuts the tip against the nip of the registration roller pair 7'to create a bend (loop), and the elasticity of the sheet material 1'makes the tip of the sheet material 1'a registration roller pair. It is in a state in which the skew is corrected along the 7'nip. This is called the loop registration method.

Further, the lateral deviation of the sheet material 1'is corrected by the lateral deviation detection sensor 2'which detects the end position of the sheet material 1'in the direction orthogonal to the conveying direction. The position of the end portion is detected, an electric signal is transmitted to a circuit (not shown), the amount of lateral deviation of the sheet material 1'is calculated, and a mechanism for correcting the lateral deviation is operated to control the lateral deviation. There are mainly the following two mechanisms for correcting this lateral displacement.

The first method will be described with reference to FIG. FIG.
Is the photosensitive drum 10 'with the registration roller pair 7'of FIG.
It is the figure seen from the side. In FIG. 12, while the sheet material is slightly bitten by the registration roller pair 7 ′, the registration roller pair 7 ′ is moved in the axial direction as indicated by an arrow A (lateral deviation direction of the sheet material) to shift the lateral deviation of the sheet material. to correct.

Information on the lateral deviation amount of the sheet material 1'in the course of conveyance detected by the lateral deviation detection sensor 2'is passed through an arithmetic circuit to control a stepping motor (not shown), and its power is transmitted to the pinion 17 '. , Registration roller pair 7 '
The registration roller pair 7'is moved in the axial direction (arrow A) by the engagement with the rack 15a 'on the lower surface of the block 15' which is connected to one of the shafts. As a result, the sheet material 1'is moved to a predetermined position and the lateral deviation is corrected.

The second method is based on recent advances in digital technology. After the document is read once by digitizing the document reading and image formation, the image information is electrically encoded and stored in the memory. At the time of image formation, the image information in the memory is read out and an image corresponding to the image information is formed on the photoconductor by an exposure device such as a laser beam or an LED array. At that time, the information detected by the lateral deviation sensor is fed back, and the lateral deviation can be corrected by forming the image position formed on the photoconductor in accordance with the lateral deviation of the sheet material.

As described above, the skew and lateral displacement of the sheet material are corrected. In the above-mentioned conventional example, the amount of lateral deviation of the sheet material is generally detected when the leading edge of the sheet material hits the nip of the registration roller pair (a place where the sheet material is stopped for a moment). (State of FIG. 13) Several methods have been devised as the detecting means, and main conventional examples are shown in FIGS. 11 (a) and 11 (b).

11 (a) and 11 (b) are cross-sections E of FIG.
E is shown.

The sheet material 1'in FIG. 11 is a cross section of the sheet material 1'abutting the registration roller pair 7'in FIG. 13 as seen from the drum direction. Reference numeral 2 "is a sensor for detecting a lateral deviation, and 9'is a line indicating a position in a direction orthogonal to a conveyance direction which is a boundary between the sheet conveyance path and the outside of the conveyance path, and is a boundary line from the boundary line 9 '. The left side of the figure is the place where the sheet material cannot be conveyed.The term "conveying path" here takes into consideration the deviation (lateral deviation) in the direction orthogonal to the conveying direction of the sheet material (hereinafter referred to as the axial direction). is there.

FIG. 11A shows a case where a photo sensor is used as the lateral deviation detection sensor. The photo sensor 2 "is in a standby position (hereinafter referred to as HP
(Home position)). When the sheet material 1'is in the state shown in FIG. 13, the photosensor 2 "on the HP moves in the direction of arrow B to detect the axial end portion of the sheet material 1'and the edge of the sheet material 1'is detected. The sheet is detected, and the moving distance therebetween is l _1. Here, the arrow A indicates the lateral displacement direction (same as the axial direction) of the sheet material.

The photo sensor 2 "is generally composed of a light emitting portion 2a 'and a light receiving portion 2b', and outputs an electric signal when the space between them is interrupted. The photo sensor detects the edge of the sheet material and electrically outputs it. When the signal is output, the moving means (not shown) stops the movement of the sensor 2 ″ and transmits the moving amount to the arithmetic circuit, whereupon the lateral shift amount of the sheet material 1 ′ can be known. In order to correct the lateral shift amount, the lateral shift is corrected by the above-mentioned two methods or the like.

Therefore, in this detection method, l _{1 is determined} depending on the size of the width of the sheet material (length in the direction crossing the conveying direction).
, The time required for detection varies.

FIG. 11B shows a detecting means using a line sensor 20 'in place of the photosensor of FIG. 11A. The line sensor 20 'includes a light emitting section 20a' and a light receiving section 20.
b ′ is continuous between L ₁ and the output is different between the portion of l ₂ with and without the sheet material. Thereby, the edge of the sheet material can be detected, and the control for correcting the lateral deviation is performed based on the detected information. Therefore, when the line sensor is used, it is not necessary to use the moving means of the sensor as in the conventional example shown in FIG.

There is also a device in which a large number of photosensors are provided in place of the line sensor of FIG. 11 (b).

The method of correcting the skew and the lateral deviation of the sheet material in the copying machine has been described above. Next, the operation flow thereof will be described. FIG. 10 shows an operation flow of the above conventional example. The size of the sheet as the sheet material set in the cassette is previously detected by the size detection sensor,
(901) Before the start, the lateral displacement sensor is waiting at the standby position (HP) outside the transport path (9).
02). When starting (903), the document reading means scans the document, and (904) the paper suitable for the document is fed from the cassette (905). When the paper is conveyed to the detection position (906), the sensor is moved to detect the end of the paper to detect the lateral deviation (907) and correct (908), and the paper is conveyed to the image forming unit (( 909), the paper is conveyed to the paper discharge tray through the fixing device, and the copy is completed.

In other image forming and image reading apparatuses, skewing and lateral deviation of the sheet material are corrected by the same method.

By the way, there are mainly two methods for feeding the sheet material, one is based on one side and the other is based on the center.

The one-sided reference means that the sheet material is
Either one of the end parts orthogonal to the traveling direction of the sheet material,
It is a method to always send the sheet material according to the standard. 14
As shown in (b), the sheet material is fed with one side as a reference regardless of the size. This method has a simple optical system configuration and has excellent processability when the sheet material is jammed.

However, there is a drawback that the transportability of the sheet material is not stable due to the difference in pressure balance between the center and the end of the roller. The central standard was devised for more stable transport performance. Therefore, in recent trends, the feeding of the sheet material based on the central standard is becoming standard. In the center-based feeding method, the sheet material is fed based on the center of the roller as shown in FIG.

[0026]

However, the standby position HP of the sensor for detecting the skew and the lateral deviation of the sheet material in the above-mentioned conventional example becomes one obstacle to increase the conveying speed. Since the sheet material is once stopped by the pair of registration rollers and the lateral deviation is detected during that time, in the conventional method, there is a difference in detection time depending on the size of the sheet material. This is the time (distance) that the lateral deviation detection means moves
However, it depends on the size (width) of the sheet material. Therefore, this movement amount increases as the size of the sheet material in the width direction decreases. (In case of central reference sheet material conveyance) Especially, since the number of types of sheet material that can be used in one model has recently increased, it can be said that the influence of the lateral deviation detection time tends to increase.

Further, when a continuous range can be detected by a CCD or a line sensor using a large number of photosensors, the above problem of the moving time can be solved, but the cost becomes high and generally only an expensive device can be used. Currently, it cannot be used.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its object is to prevent skewing and lateral deviation of the sheet material without lowering the conveyance speed with an inexpensive structure. It is an object of the present invention to provide a sheet material conveying device for detecting, an image forming apparatus including the same, and an image reading device.

[0029]

In order to achieve the above object, in the present invention, a means for detecting the size of the sheet material stored in a plurality of cassettes for supplying the sheet material, a posture of the sheet material, and In a sheet material conveying device provided with means for aligning the position, the standby position of the detecting means of the means for aligning the posture and position of the sheet material is set to the maximum width of the size of the sheet material accommodated in the plurality of cassettes. A first standby position that moves to a minimum and waits, and a standby position of the detection unit that is transported from the first standby position according to the size of the sheet material that has been transported after the transport has started. A second standby position is provided, which moves slightly outward or inward from the end of the sheet material in the width direction and stands by.

The second standby position may be a position where the sheet material always crosses so that the presence or absence of the sheet material can be detected at the same time.

Further, two or more detecting means having the first and second standby positions may be provided.

The image forming apparatus and the image reading apparatus may be configured to include the sheet material conveying device.

[0033]

In the sheet material conveying apparatus configured as described above, detection of means for aligning the posture and position of the sheet material in accordance with the maximum and minimum size widths of the sheet materials stored in the plurality of cassettes By moving the means, the time for the movement of the detection means is optimized regardless of which sheet material among the sheet materials stored in the plurality of cassettes is conveyed.

After the conveyance is started, the standby position of the detecting means is set to the first position according to the size of the sheet material being conveyed.
From the standby position, the second standby position is provided, which moves slightly outward or inward from the widthwise end of the sheet material being conveyed and stands by, thereby moving to detect the posture and position of the sheet material. The movement amount of the detection means is reduced. Further, if the sheet material always crosses the second standby position and the presence / absence of the sheet material is simultaneously detected, the existing detection means can be made multi-functional.

Further, if two or more detecting means having the first and second standby positions are provided, the posture of the sheet material can be detected more accurately by the detecting operation of the plurality of detecting means.

If the image forming apparatus and the image reading apparatus are provided with the above-described sheet material conveying device, the posture and position of the sheet material can be adjusted without causing a decrease in the conveying speed.

[0037]

FIG. 1 shows the first embodiment of the present invention. FIG. 1 shows a state in which a sheet material collides with the nip of the registration roller pair 7 in the sheet material conveying apparatus to which the present invention is applied. Now, it is assumed that the maximum width of the sheet material in the cassette is A4, It is the figure which considered the case of A4R to the minimum width, and made the size fit. The photo sensor 2 as a detection means is attached to the tip of the sensor moving member 5, and the rack 5a at the other end meshes with the pinion 4 that transmits the power from a stepping motor (not shown), and is movable in the direction of arrow B. There is. Here, C is the transport direction.

Referring to FIG. 1 according to the operation flow of the present invention of FIG. 2, the sheet material size in the cassette accommodating the sheet material is detected before the copy start button is pressed ( 201). Next, the maximum and minimum axial sizes (widths) are searched (202). (And as an example A4 (maximum width) and A4R (minimum width) in this case.) The photo sensor 2 of FIG. 1 {(A4 width) - (the width of the _{A4R)} ÷ 2 = l a} = l b It moves to a position (first HP) such as and waits until it starts (203).

[0039] and l _b is a moving distance required for the detection of the photo sensor 2 when the sheet of A4 size is conveyed without lateral displacement (normal transport position). l _{a is} also A4R
Is the distance traveled when the size is. That is, it is the first HP that the movement distance is the same for both A4 (maximum width) and A4R (minimum width).

Next, when the copy button is pressed (204) and started, the document reading device scans the document (2
05), the sheet material suitable for the original is fed from the cassette (206). That is, the size of the sheet material being conveyed is known at this point. Therefore, the photo sensor 2 is moved to the second HP as shown in FIG. The second HP is the inner side (or the outer side) of the conveyance path with respect to the position when the end of the sheet material in the axial direction (width) is not laterally displaced.
Is to set the standby position (HP) of the photo sensor 2.

If the standby position of the photo sensor is brought to a normal position without lateral displacement, the reading width L _{2 of the} photo sensor itself depends on the reading sensitivity of the photo sensor, as shown in FIG. If a sheet material comes in between, accurate detection may not be possible. Normally, this width is within an error range, but when the sheet material 1 comes within the reading width L ₂ as shown in FIG. 8, it becomes unclear which side of the arrow B the photo sensor 2 may be moved to. .

For this reason, the second HP is placed inside (or outside) the sheet material in advance so as not to be as shown in FIG.
It is a small shift.

The position is set inside (outside) of the normal position (for example, 10 mm or less) according to the lateral displacement performance of the apparatus, and can be further reduced.

Now, an A4 size sheet material will be described as an example with reference to FIG. FIG. 3A shows a state in which the photosensor 2 is waiting at the first HP, and after the start, the photosensor 2 moves to the second HP in FIG. 3B and is waiting. Is. Second HP of FIG. 3 (b)
As a result, the photo sensor 2 moves in the direction of the arrow Bs until the end of the sheet material is present and detects it. The state at that time is shown in Figure 3.
It is (c). After the detection, the movement is stopped, and thereafter, in the continuous copy, it returns to the second HP and waits again, and when it is the last sheet for which copying is completed, it returns to the first HP and waits.

Next, the case of the A4R size will be described with reference to FIG. The second from the start of the start as in the case of A4 size
Move to HP and wait. The state is shown in FIG. However, unlike the case of A4 size, the second HP is a position where the A4R sheet material does not cross the photo sensor 2. That is, the second HP waits within the sheet material size when moving outward (Bs direction) from the position of the first HP, and waits outside the sheet material size when moving inward (Bv direction). The distance traveled is always the same. This minimizes the fluctuation of the movement amount of the photo sensor 2 regardless of the size. Similarly to the A4 size, when the sheet material arrives, the photo sensor 2 moves in the direction of the arrow Bu and moves to the end portion of the sheet material. (FIG. 4B) Further, the detection method is slightly different depending on whether the sheet material crosses the photo sensor 2 or not, so that it will be described below.

FIG. 5 shows the state in which the present invention is applied to the state similar to that of FIG. 11 of the conventional example.

FIG. 5A shows the case where the sheet material 1 does not cross the photo sensor 2 when the sheet material 1 is conveyed to the detection position (at A4R). In this case, the photo sensor 2 is moved in the direction of Bu to detect the edge of the sheet material. That is, the stepping motor (not shown) in FIG. 2 is rotated to transfer the power from the pinion 4 to the rack 5a to move the photosensor 2 and stop the stepping motor when the edge of the sheet material is detected. It is calculated from the number of rotations and the control to correct the lateral deviation is performed. The procedure will be corrected as usual.

In FIG. 5B, there is a case where the sheet material 1 crosses the photosensor 2 (at A4) contrary to FIG. 5A, but an electric signal until the end of the sheet material 1 is detected. The initial value of is only reversed, and the other procedures are the same to control the correction of lateral deviation.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention.
An example of is shown.

In the second embodiment, regardless of the size of the sheet material, the second HP of the first embodiment is always provided at the position crossing the sheet material to detect the presence or absence of the sheet material at the same time. It is used to match the timing of image formation and the like.

Specifically, the second HP (FIG. 4A) for detecting the lateral deviation of the A4R of the first embodiment is as shown in FIG. As a result, the photo sensor 2 which was exclusively used for detecting the lateral deviation in the first embodiment can perform two roles. When the sheet material is conveyed, first, in the second embodiment, the photo sensor 2 is always crossed to detect the leading edge of the sheet material. Then, similarly to the first embodiment, the lateral displacement is detected and corrected. Further, the rear end of the sheet material can be detected by moving the photo sensor 2 to the second HP again while the sheet material is being conveyed to the position of the photo sensor 2.

(Third Embodiment) FIG. 7 shows a third embodiment.

When performing the continuous copying of the first embodiment, etc.
When returning to the second HP again, that is, when returning from FIG. 3 (c) to FIG. 3 (b), the photo sensor 2 is once moved to the outside of the sheet material in FIG. The second HP (FIG. 3B) will be returned to.

Therefore, when returning to the second HP such as continuous copying, the second HP is provided in the moving direction in order to detect from the second HP.

Specifically, after the photo sensor 2 moves to the arrow Bs from the second HP of FIG. 3 (b) to detect the widthwise end portion of the sheet material, the position of FIG. 7 is changed to the next sheet material. It is to be the second HP until comes.

FIG. 7 is the same as the case where the photo sensor stands by outside the sheet material of the first embodiment. The second HP repeats the inside and outside of the sheet material each time the sheet material arrives, thereby increasing the processing speed during continuous copying.

(Fourth Embodiment) In the fourth embodiment, the detecting means of the first to third embodiments is attached side by side along the sheet conveying direction to detect skew. Can also be used for. In that case, it is possible to cope with the laser writing position without correcting the skew in the registration roller pair.

In this case, since the conveyance state of the paper is clearly known, the image formation on the photosensitive drum is performed in conformity with the paper. The control example is shown in FIG.

In the figure, the image forming process is shown in a simplified manner for simplification of explanation, and the image forming state when the paper is straightly sailed is shown in FIG. 9 (a). This is a state in which, as the paper is conveyed, the photosensitive drum is exposed and irradiated by a laser which is an image exposing means, and is transferred onto the paper.

On the other hand, FIG. 9B shows an image forming state when the sheet is skewed. Skew amount of paper,
Since the lateral registration amount is already known by the above-mentioned detection means of the edge portion of the paper, the laser light for exposing and irradiating the photosensitive drum is irradiated in the order of → → → → → → → →. Fig. 9 (b) shows the state when it is transferred to the paper.
Is the state indicated by.

The rearrangement of the order of the images irradiated onto the photosensitive drum can be easily performed by arithmetically processing the information in the information storage device (memory) provided in the main body of the image forming apparatus. As a result of performing these processes, it is possible to always form an image in which the position is correctly matched relative to the sheet even if the sheet is skewed or laterally displaced.

[0062]

According to the present invention having the above-mentioned structure and operation, there is provided means for adjusting the posture and position of the sheet material in accordance with the maximum and minimum size widths of the sheet materials accommodated in the plurality of cassettes. By moving the detection means to the first standby position, the time for the movement of the detection means is optimized regardless of which sheet material among the sheet materials stored in the plurality of cassettes is conveyed. By moving the sheet material to the second standby position according to the size of the conveyed sheet material and moving the detection means to detect the posture and position of the sheet material from that position, the detection time can be shortened and the cost is high. Transport speed can be increased without using multiple line sensors or multiple photo sensors, resulting in shorter job times.

At the same time, since the moving amount of the detecting means is reduced, the power consumed by the moving means of the detecting means is saved. Furthermore, in the case of digital machines, it is possible to increase the number of sheets processed in a unit time by improving the productivity by shortening the moving time of the detection means to reduce the distance between the sheet materials without changing the conveyance speed. It becomes possible.

Further, since the presence or absence of the sheet material can be detected at the same time by always making the second standby position a position where the sheet material crosses, it is possible to eliminate the sensor conventionally provided for that purpose and reduce the cost. Also becomes.

If two or more detecting means having the first and second standby positions are provided, the posture (skew) of the sheet material can be simultaneously detected by the detecting operation of the plurality of detecting means, and the posture defect can be detected in the sheet material. It can be done at the same time as the position detection.

Further, by changing the irradiation position of the laser in accordance with the detected posture of the sheet material, it is possible to provide a simple and low-cost lateral deviation / skew correction means, and to speed up the sheet material conveyance.

If the image forming apparatus and the image reading apparatus are provided with the above-mentioned sheet material conveying device, the posture and position of the sheet material can be detected and the job time can be shortened without lowering the conveying speed.

[Brief description of drawings]

FIG. 1 is a diagram of a first HP of a first embodiment.

FIG. 2 is an operation flow chart of the present invention.

FIG. 3 is a second H of the first embodiment, taking A4 as an example.
The figure which showed P and the operation order.

FIG. 4 is a diagram showing an example of A4R of the first embodiment.

FIG. 5 is a diagram showing a detection method of a photo sensor.

FIG. 6 is a diagram of a second embodiment.

FIG. 7 is a diagram of a third embodiment.

FIG. 8 is an enlarged view of a reading unit of the photo sensor.

FIG. 9 is a diagram of a fourth embodiment.

FIG. 10 is an operation flow chart of a conventional example.

FIG. 11 is a diagram showing a method of detecting a photo sensor and a line sensor of a conventional example.

FIG. 12 is a conventional lateral misalignment correction mechanism.

FIG. 13 is a diagram of an image forming unit of a conventional example.

FIG. 14 is a diagram illustrating a case where the transport method is different.

[Explanation of symbols]

 1, 1'sheet material 2, 2 ', 2 "photo sensor (detection means) 4 pinion 5 sensor moving member 7, 7'register roller pair arrow A lateral deviation direction arrow B lateral deviation detection sensor moving direction arrow C sheet material Transport direction

Claims (5)

[Claims] 1. A sheet material conveying apparatus, comprising: a means for detecting the size of the sheet material housed in a plurality of cassettes for supplying the sheet material; and a means for aligning the posture and position of the sheet material. The first standby position for moving the standby position of the detection means of the means for aligning the posture and position of the sheet material accommodated in the plurality of cassettes to the maximum and minimum of the width of the size of the sheet material and waiting, and the start of transportation. After that, according to the size of the sheet material being conveyed, the standby position of the detecting means is moved from the first standby position to a position slightly outside or inside the end portion in the width direction of the sheet material being conveyed and stands by. A sheet material conveying device characterized in that a second standby position is provided. 2. The sheet material conveying device according to claim 1, wherein the second standby position is a position where the sheet material always crosses, and the presence or absence of the sheet material can be detected at the same time. 3. The sheet material conveying device according to claim 1, wherein two or more detecting means having the first and second standby positions are provided. 4. A sheet material conveyer, wherein means for detecting the size of the sheet material housed in a plurality of cassettes for supplying the sheet material and means for aligning the posture and position of the sheet material are provided in front of the image forming section. An image forming apparatus including an apparatus, wherein the sheet material conveying device is the sheet material conveying device.
An image forming apparatus comprising. 5. A sheet material conveyer, wherein means for detecting the size of the sheet material housed in a plurality of cassettes for supplying the sheet material, and means for aligning the posture and position of the sheet material are provided in front of the image reading section. An image reading apparatus including the apparatus, wherein the sheet material conveying apparatus is the sheet material conveying apparatus.
Alternatively, an image reading device consisting of 3.