JP2005320141A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of conveying a paper in substantially vertical upward direction and reducing height of the device without increasing width and depth of a device main body to miniaturize the device. <P>SOLUTION: A multi-paper feeding separation pad 4 of a multi-paper feeding part is attached to a paper feeding cassette 11. Although the separation pad 4 must cross over a paper feeding roller 1 when attaching and detaching the paper feeding cassette 11, a butting collar 1b presses the separation pad 4 down while rotating to attach and detach the paper feeding cassette 11 with low resistance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus provided with a paper feeding device such as a copying machine, a laser printer, and a facsimile machine.

  FIG. 9 is a cross-sectional view showing a first example of an image forming apparatus using electrophotography with a conventional paper feeding device. The overall configuration of the image forming apparatus will be described below with reference to FIG.

  In FIG. 9, an upper part A is an image forming apparatus, 101 is a process cartridge in which electrophotographic process parts such as a photosensitive drum 101a and a charging roller, a developing sleeve, a cleaning unit, and a toner container are integrated, 102 is a laser exposure apparatus, A laser scanner 103 having a reflecting mirror integrated therein, and 103 are transfer rollers, each of which is provided with four sets, and multicolor development is possible.

  Reference numeral 104 denotes a fixing device, and an image forming unit of the image forming apparatus is within the frame of the two-dot chain line shown in the figure. Reference numeral 105 denotes a registration roller, 106 denotes a paper discharge roller, 107 denotes a paper discharge tray, and 108 denotes a re-feed conveyance roller provided in a double-sided re-feed conveyance path where paper is re-fed in automatic duplex printing. A lower part B is a paper feeding device, and a user feeds a large amount of standard paper by using a multi-paper feeding unit B1 that inserts and uses a small amount of various sizes of paper according to the user's application from the outside of the device. A paper feed cassette unit B2 is provided.

  Hereinafter, the operations of the entire image forming apparatus and the sheet feeding apparatus will be described with reference to FIG.

  The photosensitive drum 101a rotates in the direction of the arrow and is uniformly charged by a charging roller that is fed from a high voltage power source (not shown). Laser light emitted from the laser scanner 102 is applied to the photosensitive drum 101a, and an electrostatic latent image is formed on the photosensitive drum 101a. The toner container is filled with toner. As the developing sleeve rotates, an appropriate amount of toner is appropriately charged and then supplied onto the photosensitive drum 101a. The toner on the developing sleeve is transferred to the photosensitive drum 101a. The latent image is attached to the electrostatic latent image and is developed and visualized as a toner image. These developing operations are performed in the process cartridge 101.

  The multi-sheet feeding unit B1 or the sheet feeding cassette B2 takes a timing to feed the sheets one by one, and only one uppermost sheet is separated and conveyed for each sheet feeding by a separating unit (not shown). Then, the image is conveyed to the image forming unit via the registration roller 105. The visualized toner image on the photosensitive drum 101 a is transferred onto the paper by the transfer roller 103. The untransferred toner remaining on the photosensitive drum 101a without being transferred is stored in a waste toner container by a cleaning blade, and the photosensitive drum 101a whose surface has been cleaned repeatedly enters the next image forming process. These operations are also performed in the process cartridge 101.

  The paper on which the toner image is placed is heated and pressurized by the fixing device 104, and the toner image is permanently fixed on the paper. The sheet on which the image is fixed is bent above the fixing unit and is discharged to the discharge tray 107 at the upper part of the apparatus main body by the discharge roller 106. The arrows in the figure indicate the sheet conveyance path. Also, during automatic duplex printing, as shown in FIG. 9B, the paper is nipped by the paper discharge roller 106 and switched back and fed again through the conveyance path indicated by the arrow and sent to the registration roller 105. And an image is formed on the back surface.

  Arrows A to C in FIG. 9B indicate the access direction of the user, arrow A indicates the direction in which the process cartridge is attached and detached, and arrow B indicates the direction in which sheets are stacked on the multi-sheet feeder. In addition, the cassette paper feeding unit can be attached and detached in the direction of arrow C and can load paper, and all access is from the left side of the drawing. It is general that it is.

  This conventional example is a typical configuration in which a double-sided refeed conveyance path is added to an image forming apparatus in which an image forming conveyance path provided with an image forming unit conveys paper in a substantially vertical upward direction. In the example, there are four sets of process cartridges and transfer rollers, and an example of a color direct transfer type image forming unit that transfers four colors directly to recording paper has been described. However, only one pair of process cartridges and transfer rollers can be used for single color printing. There are four pairs of image forming units, process cartridges, and transfer rollers to perform. In the color indirect transfer type image forming unit that sequentially transfers to the intermediate transfer member and then batch transfer again to the recording paper, and other printing type image forming units Even if it is replaced, the overall configuration is almost the same.

  Various methods have been put to practical use as methods for separating and feeding only the uppermost sheet for each sheet feeding in the sheet feeding device, and are used properly depending on the required performance of each sheet feeding device. In a conventional multi-feed unit and cassette feed unit, a friction separating pad method or a retard roller method having a simple configuration and capable of separating paper of various thicknesses is often used.

  Hereinafter, the configuration of the friction separating pad type paper feeding device will be described with reference to FIG. 7A and 7B are diagrams for explaining a conventional friction separation pad system. FIG. 7A is a perspective view, and FIGS. 7B and 7C are views from the direction of arrow A in FIG. FIG.

  In FIG. 7, 51 is a paper feed roller capable of transporting paper, 52 is a retracted position (FIG. 7B) that is separated from the paper feed roller 51, and a pressure contact position that is in pressure contact with the paper feed roller 51 (FIG. 7C). A paper stacking base 52a that is rotatably held between the paper stacks, 52a is the center of rotation, and 53 is a paper for biasing the paper stacked on the paper stacking base 52 in a direction to press the paper feeding roller 51. A paper stacking base spring 54 acting in a direction to push up the stacking base 52, 54 is a retracted position (FIG. 7B) separated from the paper feed roller 51 and a pressure contact position (FIG. 7C) pressed against the paper feed roller 51. Separation pad which is a separation means for separating the sheets one by one while being rotatably supported, 54a is the center of rotation, 55 is a direction in which the separation pad 54 is pushed up to press the separation pad 54 against the paper feed roller 51 Separating pad spring acting on 57 Against the action force of the sheet stacking plate spring 53 is cam capable of moving to the retracted position by depressing the sheet stacking tray 52.

  As shown in FIG. 7B, when the cam 57 pushes down the paper stacking base 52, the protrusions 52a and 52b on the bottom surface of the paper stacking base 52 push down the separation pad 54, thereby moving the separation pad 54 to the retracted position. On the contrary, when the cam 57 does not push down the paper stacking base 52, the separation pad 54 is in the pressure contact position as shown in FIG. 7C. Reference numeral 58 denotes a paper feed shaft in which the paper feed roller 51 and the cam 57 are coaxially fixed. A paper feed signal is input to the apparatus by an intermittent drive mechanism combining a missing gear 59 and a solenoid 60 as shown in the figure. Then, the intermittent rotation operation which stops once and stops is possible. Reference numeral 61 denotes a frame body that supports the members 51 to 60.

  Hereinafter, the operation of the friction separating pad type paper feeding device will be described with reference to FIG. (A)-(d) is a schematic diagram for explaining the operation, with a paper feed roller 51, a paper stacking base 52, a separation pad 54, and a cam 57 inside the apparatus on the left side, and a gear missing gear on the side of the apparatus on the right side. 59, the solenoid 60 is drawn, and the one-dot chain line indicates that the missing gear 59 and the cam 57 are coaxially supported by the paper feed shaft 58.

  FIG. 6A is a diagram illustrating a paper feeding operation standby state. In the standby state, the paper stacking base 52 is pushed down by the cam 57 and is in the retracted position. When the activation signal is input to the apparatus, the solenoid 60 is pulled in the direction A and the toothless gear 59 rotates in the direction B, whereby the paper feed shaft 58, the paper feed roller 51, and the cam 57 start to rotate. .

  (B) is a diagram immediately after the rotation of the paper feed shaft 58 is started. When the cam 57 shifts from the phase in which the sheet stacking table 52 is pushed down to the phase in which the cam 57 is separated, the sheet P loaded on the sheet stacking table 52 is brought into a pressure contact position where the sheet P is pressed against the sheet feeding roller 51 by the action of the sheet loading table spring. Moving.

  FIG. 6C is a diagram illustrating a state in which the rotation of the paper feeding shaft 58 proceeds and the paper feeding roller 51 feeds paper. The friction conveying force by the paper feed roller 51 acts on the uppermost sheet, and the frictional force of the separation pad 54 acts on the back surface of the lower sheet so that only the uppermost sheet is separated and conveyed.

  FIG. 6D is a diagram showing a state where the rotation of the paper feeding shaft 58 has further progressed. At this time, the cam 57 shifts from a phase separated from the paper stacking base 52 to a phase in which the paper stacking base 52 is pushed down, and the paper stacking base 52 moves to the retracted position as shown in the figure. For this reason, the conveyance force by the paper feed roller 51 does not act on the uppermost sheet, but at this point, the leading edge of the sheet has reached the next conveyance roller, and only one sheet is continuously conveyed to the uppermost layer. The Thereafter, when the paper feed shaft 58 makes one round and returns to the state (a), the intermittent operation of the paper feed shaft 58 ends and stops.

  As described above, when separating and transporting sheets, the sheet stacking base 52 is in the pressure contact position, but when the separating and transporting operation is finished, the sheet stacking base 52 is moved to the retracted position by the action of the cam 57.

  In an image forming apparatus configured such that the image forming conveyance path as shown in FIG. 9 conveys paper in a substantially vertical upward direction and pulls out the cassette in the direction of the multi paper feed unit, <A: cassette height + B: multi paper feed unit The height of the upper portion of the multi-sheet feeding unit is determined by the height>, and the height of the apparatus is increased. In order to solve this, if it is configured as shown in FIG. 10 (a), the size can be reduced. However, since it interferes with the multi-sheet feeder B1, the cassette cannot be pulled out in the direction A in the figure. Must be pulled out in a direction perpendicular to the drawing.

  At this time, the user access direction for cartridge removal, loading of paper into the multi-feed unit, jam processing, etc. is the direction of arrow B, but only the paper feed cassette has a different access direction. Is necessary, so usability is poor. Further, as a configuration proposal for pulling out the paper feed cassette from the direction A in the figure, it is also possible to pull out the multi paper feed unit integrally as shown in FIG. 10B (see, for example, Patent Document 1).

JP 2001-225993 A

  However, the configuration shown in FIG. 10B has a problem that the drive transmission mechanism is complicated, and there are many technical problems to realize. In addition, since the drawer cassette is large, there is a serious problem that usability is poor.

  The present invention solves the above-described conventional problems. In an image forming apparatus that conveys a sheet in a substantially vertical upward direction, the apparatus height is reduced without increasing the width and depth of the apparatus main body. The purpose is to reduce the size.

  In order to achieve the above object, an invention according to claim 1 is directed to an image forming unit, an image forming conveyance path that is capable of conveying a sheet and that is provided in the image forming unit and that conveys a sheet in a substantially vertical upward direction, and the image. A paper feed cassette provided on the upstream side of the forming conveyance path, a cassette paper feed unit for carrying the paper one by one to the image forming unit, and a position facing the cassette paper feed unit. A multi-sheet feeding unit capable of stacking and continuous feeding corresponding to a plurality of sizes of paper, and a paper feeding unit provided between the sheet feeding unit and the image forming conveyance path to supply the image forming conveyance path. A paper feed conveyance path through which the paper to be fed passes, and a paper discharge roller provided on the downstream side of the image formation conveyance path for conveying the image-formed paper discharged from the image formation conveyance path, Part of the paper separating means of the multi-sheet feeder in the paper cassette Characterized by providing.

  According to a second aspect of the present invention, in the first aspect of the present invention, a part of the paper separating means is a separation pad or a retard roller that forms a lower part of a paper separation nip portion.

  According to a third aspect of the present invention, in the first aspect of the present invention, a part of the sheet separating unit is a lift-up unit for pressing the sheet against the sheet feeding roller and a separation pad that forms a lower part of the sheet separating nip portion. It is characterized by being.

  According to the first aspect of the present invention, in the image forming apparatus configured such that the image forming conveyance path provided with the image forming unit conveys the sheet in a substantially vertical upward direction, the separation pad portion of the multi-sheet feeding unit is cassette fed. The multi-feed unit can be placed at a lower position than before by pulling out the multi-feed separation pad when pulling out the feed cassette. it can.

  According to the second aspect of the present invention, in the image forming apparatus configured such that the image forming conveyance path provided with the image forming unit conveys the sheet substantially vertically upward, the retard roller of the multi-sheet feeding unit is fed into the cassette. The multi-sheet feeding unit can be disposed at a lower position than the conventional one, and the apparatus can be downsized.

  According to a third aspect of the present invention, in the image forming apparatus having a configuration in which the image forming conveyance path provided with the image forming unit conveys the paper in a substantially vertical upward direction, the separation pad and the sheet feeding middle plate of the multi paper feeding unit Is placed in the paper cassette of the cassette paper feeder, and the multi paper feeder is placed at a lower position than in the past by pulling out the multi paper feed separation pad and the paper feeding plate together when the paper cassette is pulled out. And the size of the apparatus can be reduced.

  In the following, embodiments of the present invention will be described, but description of parts common to conventional examples such as operations and components from paper feeding to image formation will be omitted.

<Embodiment 1>
1A and 1B are diagrams of an image forming apparatus according to Embodiment 1 of the present invention, in which FIG. 1A is a sectional view of the entire apparatus, and FIG. 1B is a detailed sectional view of a multi-feed unit.

  In FIG. 1, reference numeral 1 denotes a paper feed roller capable of transporting paper, which is composed of a rubber roller portion 1a and a rotatable butting collar portion 1b. Reference numeral 2 denotes a multi-feed middle plate that is operatively held between a retracted position separated from the paper feed roller 1 and a press-contact position that presses against the paper feed roller 1, and 3 is stacked on the multi-feed middle plate 2. In order to urge the paper to be pressed against the paper feed roller 1, a multi-medium leaf spring 4 acting in the direction of pushing up the multi-paper feed middle plate 2 is held so as to be rotatable about 4c and holds one sheet of paper. Separation pads 5 which are separation means for separating each one, a separation pad spring 5 acting in a direction to push up the separation pad 4 in order to press the separation pad 4 against the paper feed roller 1, and 6 a multi-feed medium plate 2 and a multi-feed. An intermediate plate holding plate for supporting the paper tray spring, 7 is a multi-feed tray for stacking sheets, and 8 is a feed shaft to which a cam (not shown) for raising and lowering the feed roller 1 and the multi-feed intermediate plate 2 is fixed. As in the conventional example of FIG. The intermittent drive mechanism combined with the id enables an intermittent rotation operation that stops once when a paper feed signal is input to the apparatus, and the paper feed operation method of the multi-paper feeder is the same as the conventional example. It is the same.

  Reference numeral 11 denotes a paper feed cassette on which paper fed from the cassette paper feed roller 21 is stacked. The separation pad 4 and the separation pad spring 5 are fixed to the paper feed cassette 11.

  In the overall sectional view of the apparatus (a), 101 is a process cartridge in which electrophotographic process parts such as a photosensitive drum 101a and a charging roller, a developing sleeve, a cleaning means, and a toner container are integrated, and 102 is a laser exposure apparatus and a reflection mirror. The integrated laser scanner, 103 is a transfer roller, 104 is a fixing device, and the inside of the dotted line frame configured as above is an image forming unit of the image forming apparatus. Reference numeral 105 denotes a registration roller, 106 denotes a paper discharge roller, 107 denotes a paper discharge tray, and 108 denotes a re-feed conveyance roller provided in a double-sided re-feed conveyance path during automatic duplex printing. It is.

  The feature of the present embodiment is that the multi-feed separation pad 4 of the multi-feed section is attached to the feed cassette 11. For this reason, the multi-sheet feeding portion B that has been conventionally arranged only above the height A of the sheet feeding cassette as shown in FIG. 9 can be arranged at a lower position, and the relationship C <A + B as shown in FIG. The increase in size of the apparatus can be eliminated.

  Next, the attaching / detaching operation of the sheet feeding cassette 11 will be described.

  The multi-feed tray 7 can be stored in the apparatus main body as shown in FIG. When the multi paper feed tray 7 is rotated in the direction of arrow D in FIG. 2, the intermediate plate support plate 6 can rotate around the paper feed shaft 8 along the guide shape portion (7d in FIG. 1) of the multi paper feed tray. It is pushed up to the upper part of the apparatus by the attached link arm 12. Therefore, the multi-sheet feeding middle plate 2 and the multi-middle leaf spring 3 attached to the middle plate support plate 6 are also retracted to the position shown in FIG. As a result, there are no parts that obstruct the attachment / detachment of the paper feed cassette 11, and the paper cassette 11 can be pulled out in the direction of arrow E as shown in FIG.

  3A and 3B are diagrams showing the trajectory of the separation pad when the paper feed cassette is attached / detached, where FIG. 3A is when the paper is pulled out, FIG. 3B is when the paper is stored, and the arrow in FIG. The rotation direction and the moving direction of the paper feed cassette are shown. When the paper feed cassette is attached / detached, the separation pad 4 disposed in the paper feed cassette has to get over the paper feed roller 1, but as the abutting collar 1b rotates as shown in FIG. The paper feed cassette 11 can be attached and detached with resistance.

  As described above, in the image forming apparatus according to the present embodiment, the multi-feed separation pad of the multi-feed unit is provided in the feed cassette, and the multi-feed tray and the middle plate are the feed cassette when the multi-feed tray is stored. By retracting to a position that does not obstruct the attachment / detachment of the device, the height of the device can be lowered, and the size of the device can be reduced.

  In this embodiment, an example of color printing in which four process cartridges are provided in the image forming unit has been described. However, even in an image forming apparatus for monochrome printing in which one process cartridge is provided in the image forming unit, image formation is performed. The same effect can be obtained if the conveyance path is an image forming apparatus configured to convey a sheet in a substantially vertical upward direction. With the above configuration, the same effect can be obtained even in an image forming apparatus without a double-sided refeed conveyance path.

<Embodiment 2>
FIG. 4 is a diagram of an image forming apparatus according to Embodiment 2 of the present invention, which is an embodiment that employs a retard roller system in place of the separation pad system of the first embodiment.

  The retard roller system of the present embodiment is a so-called simple retard system in which the retard roller 41 does not have a driving force. A retard roller 41 is attached to the roller shaft 42 together with a torque limiter (not shown) fixed to the retard roller. 43 is a roller bearing, and 44 is a retard pressure spring that urges the roller bearing upward. With this configuration, the retard roller 41 is pressed against the multi-feed roller 1 with a constant spring pressure.

  The sheet feeding operation is the same as the conventional simple retard method. When only one sheet enters the pressure nip, the sheet is conveyed by the rotation of the sheet feeding roller 1 when the sheet is only one sheet, and the retard roller 41 is also rotated. . When a plurality of sheets enter the pressure nip, only the uppermost sheet is conveyed by the action of a torque limiter (not shown).

  Other configurations are the same as in the first embodiment, and when the multi-feed tray 7 is rotated and housed in the main body, the paper feed cassette can be attached and detached. As in the first embodiment, downsizing of the apparatus is achieved. it can.

<Embodiment 3>
FIG. 5 is a diagram of an image forming apparatus according to Embodiment 3 of the present invention, and FIG. 5 is a diagram when a sheet is set.

  The difference from the first embodiment is the arrangement of the multi-sheet feeding middle plate, and the sheet is stacked while being operatively held between a retracted position separated from the sheet feeding roller 1 and a pressure contacting position pressed against the sheet feeding roller 1. The multi-sheet feeding plate 51 is provided in the sheet feeding cassette 11. Accordingly, when the paper feed cassette 11 is pulled out, the multi-feed middle plate 51 is also pulled out together as shown in FIG.

  Other configurations are the same as those in the first embodiment, and the apparatus can be reduced in size as in the first embodiment.

1 is an overall cross-sectional view and a detailed cross-sectional view of a paper feed unit of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a detailed cross-sectional view of a sheet feeding unit of the image forming apparatus according to the first embodiment of the present invention. FIG. 2 is a detailed cross-sectional view of a sheet feeding unit of the image forming apparatus according to the first embodiment of the present invention. FIG. 5 is a detailed cross-sectional view of a sheet feeding unit of an image forming apparatus according to a second embodiment of the present invention. FIG. 6 is a detailed cross-sectional view of a paper feed unit of an image forming apparatus according to Embodiment 3 of the present invention. FIG. 6 is a detailed cross-sectional view of a paper feed unit of an image forming apparatus according to Embodiment 3 of the present invention. 8A and 8B are a perspective view and a cross-sectional view for explaining a sheet feeding operation of a conventional image forming apparatus. FIG. 10 is a cross-sectional view for explaining a sheet feeding operation of a conventional image forming apparatus. FIG. 7 is an overall cross-sectional view of a conventional image forming apparatus. It is sectional drawing for demonstrating the subject of the conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multi feed roller 2 Multi feed middle plate 3 Multi middle leaf spring 4 Separation pad 5 Separation pad spring 6 Middle plate holding plate 7 Multi feed tray 8 Feed shaft 11 Feed cassette

Claims (3)

An image forming unit, an image forming conveyance path that is capable of conveying the sheet and is provided in the image forming unit and is conveyed in a substantially vertical direction, and a sheet feeding unit provided on the upstream side of the image forming conveyance path. A cassette paper feeding unit that transports the paper cassette and the loaded paper one by one to the image forming unit, and a stack and continuous paper feeding corresponding to a plurality of sizes of paper that are provided at a position facing the cassette paper feeding unit. A possible multi-sheet feeding unit, a sheet feeding conveyance path provided between the sheet feeding unit and the image forming conveyance path, through which a sheet fed from the sheet feeding unit to the image forming conveyance path passes, and the image A discharge roller that is provided on the downstream side of the forming conveyance path and conveys the image-formed paper discharged from the image forming conveyance path;
An image forming apparatus, wherein a part of sheet separating means of the multi-sheet feeding unit is provided in the sheet feeding cassette.   The image forming apparatus according to claim 1, wherein a part of the sheet separating unit is a separation pad or a retard roller that forms a lower portion of a sheet separating nip portion.   The image forming apparatus according to claim 1, wherein a part of the sheet separating unit is a separation pad that forms a lower portion of a sheet separating nip portion and a lift-up unit that presses the sheet against a sheet feeding roller.

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