JPH0649441U - Paper feeder - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the paper is bent between the paper feed roller and the feed roller, smooth feeding of the paper is not hindered. [Structure] The paper P sent from the paper feed cassette 9 is
It is guided between the pair of feed rollers 16 via the curved guide 12 and the pair of paper guides 13A and 13B. Elastic sheet 14
Is fixed to the upper portion of the bending guide 12 so as to extend toward the paper guide 13B, and the sheet 14 always bends the paper P together with the bending guide 12 and feeds it between the paper guides 13A and 13B. When the bending of the sheet P acts on the inner surface of the elastic sheet 14 as a pressing force, the elastic sheet 14 is curved outwardly, and the bending portion of the sheet P absorbs the bending amount of the sheet P. Does not bend. Further, since the elastic sheet 14 presses the bent portion of the paper P toward the paper transport direction, the elastic restoring force of the paper P due to the flexure is applied toward the paper transport direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sheet feeding apparatus for feeding sheets one by one in an image forming apparatus such as a facsimile machine or a printer.

[0002]

[Prior art]

 In this type of sheet feeding device, as shown in FIG. 6, the sheets P stacked in the sheet feeding cassette 61 are fed one by one by the rotation of the sheet feeding roller 62, and the sheets P are also fed. Is turned upside down by a pair of guide members 63 curved in an arc shape and guided between a pair of feed rollers 64. Then, the paper P is fed by the rotation of the feed roller 64 and fed into an image forming unit (not shown).

Further, in the above apparatus, since the print start position on the paper P is always kept constant, the driving of the paper feed roller 62 is stopped when the front end of the paper P reaches the position of the feed roller 64. By doing so, the transfer operation of the paper P is temporarily stopped so that the front end of the paper P is always aligned with a fixed position.

However, if a slight shift occurs in the sheet transfer distance due to the rotation of the sheet feed roller 62 due to a shift in the stop timing of the sheet feed roller 62, a slip between the sheet feed roller 62 and the sheet P, etc. In some cases, the drive of the paper feed roller 62 is stopped before the front end of the paper feed roller 64 reaches the feed roller 64. In such a case, even if the feeding roller 64 is rotated, the feeding roller 64 cannot transport the sheet.

Therefore, in the conventional sheet feeding apparatus, the driving of the sheet feeding roller 62 is stopped after a lapse of some time after the front end of the sheet P reaches the feeding roller 64 and is slightly inserted between the rollers 64. Even if there is a slight deviation in the sheet transfer distance by the sheet feed roller 62, the front end of the sheet P surely reaches the feed roller 64.

[0006]

[Problems to be solved by the device]

 In this case, the paper P is slightly bent between the paper feed roller 62 and the feed roller 64 because the feed roller 64 prevents the front end of the paper P from moving. However, when the bending of the paper P occurs at a position deviated from the guide member 63, for example, between the paper feed cassette 61 and the guide member 63 as shown by the chain line in FIG. The part projects outside the guide member 63. In such a case, the elastic restoring force of the sheet P due to the flexure is received by the inner wall or the end of the guide member 63 and is not sufficiently acted in the sheet transfer direction. Therefore, when the sheet P is transferred by the feed roller 64, the sheet P may not be smoothly fed, and in some cases, the bent portion of the sheet P may be caught by the end of the guide member 63 to cause a jam. There is a problem that causes. Further, even if the paper P is fed, there is a problem that the paper P is wrinkled due to being caught.

Therefore, as shown by a chain line in FIG. 6, it is conceivable that a part of the guide member 63 that allows the bending of the sheet P is formed and the part of the sheet P is bent. However, in the case of such a configuration, when the paper P sent out from the paper feed cassette 61 is transferred along the portion that allows the bending, the paper transfer path from the paper feed roller 62 to the feed roller 64. Will be longer. Then, as described above, when the paper transport distance slightly shifts due to the rotation of the paper feed roller 62, the paper feed roller 62 is driven before the front end of the paper P reaches the feed roller 64. There are cases where it is stopped. Further, the front end of the paper P sent out from the paper feed cassette 61 may be caught in a portion that allows the bending, which may cause a jam.

The present invention has been made to solve the above problems, and an object thereof is to prevent smooth feeding of a sheet even if the sheet is bent between the sheet feeding roller and the feeding roller. It is to provide a sheet feeding device that does not occur.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, according to the present invention, a sheet feeding roller that feeds sheets stacked in a sheet feeding cassette one by one and a sheet that has been fed is curved and inverted and guided between a pair of feeding rollers. A guide member is provided, and in the middle of the guide member, the paper is always guided to the feed roller side, and is moved by the pressing force from the paper to allow the paper to flex, and the elastic restoring force of the paper due to the flexure. It is provided with an elastic body that acts on the paper in the paper transport direction.

[0010]

[Action]

 Therefore, according to the present invention, the paper in the paper feed cassette is fed out one by one by the paper feed roller, and the paper is guided by the guide member between the pair of feed rollers. At this time, the elastic body provided in the middle of the guide member guides the paper to the feed roller side together with the guide member. That is, the paper sheet is smoothly guided to the feed roller side without passing through the bending allowance portion formed by the movement of the elastic body. Then, when the paper tries to bend between the paper feed roller and the feed roller, the elastic force is moved by the pressing force due to the bending, the bending of the paper is allowed, and the paper may bend at other parts. Absent. Further, at this time, the elastic restoring force of the sheet due to the bending is exerted in the sheet transfer direction by the elastic body, so that the sheet is smoothly transferred when the feed roller is rotated.

[0011]

【Example】

 An embodiment in which the sheet feeding apparatus of the present invention is embodied in an image forming apparatus will be described below with reference to the drawings.

As shown in FIG. 1, a photosensitive drum 2 is rotatably supported in a substantially central portion of an apparatus case 1, and a photoconductive film 3 is formed on an outer peripheral surface of the photosensitive drum 2. The charger 4 uniformly charges the photoconductive film 3 to a predetermined potential. The exposure device 5 forms an electrostatic latent image of a predetermined potential on the photosensitive drum 2 by irradiating light.

The developing device 6 has a toner case 7 for containing the toner T and a developing roller 8. Then, a predetermined electric potential is applied to the toner T by the developing roller 8, and the toner T is attached to the electrostatic latent image based on the difference between the electric potential and the electric potential of the electrostatic latent image. The image is visualized.

The paper feed cassette 9 is detachably attached to the lower part of the apparatus case 1, and a large number of papers P are accommodated in the paper feed cassette 9 in a stacked state. The paper feed roller 10 is disposed in the apparatus case 1 so as to be able to positively rotate, and the end of the paper P in the paper feed cassette 9 on the delivery side is pressed against the outer peripheral surface of the lower portion of the paper feed roller 10. The paper feed roller 10 is connected to a drive motor 45 shown in FIG. 4 via a one-way clutch (not shown) and an electromagnetic clutch 11, and the paper feed roller 10 is rotationally driven by the drive motor 45.

The bending guide 12 is arranged in the device case 1 so as to correspond to the paper feeding side of the paper feeding cassette 9. The pair of paper guides 13A and 13B are arranged on the downstream side of the curved guide 12, and the upstream side of the paper guide 13A arranged on the inner peripheral side is curved in an arc shape. A sheet transfer passage is formed between the sheet guides 13A and 13B and between the curved guide 12 and the arcuate portion of the inner sheet guide 13A. In this embodiment, the curved guide 12 and the paper guides 13A and 13B form a guide member.

A pair of feed rollers 16 are arranged downstream of the paper guides 13A and 13B. The feed roller 16 is composed of a drive roller 16a connected to the same drive motor 45 as the paper feed roller 10 via an electromagnetic clutch 17, and a driven roller 16b in contact with the drive roller 16a. .

Then, by rotating the paper feed roller 10, the paper P is sent out from the paper feed cassette 9 one by one. The sheet P is conveyed to the lower part of the photosensitive drum 2, that is, the image forming section, through the sheet guides 13A and 13B, the feed roller 16, and the sheet guide 18 while being curved and inverted by the curved guide 12.

As shown in FIGS. 1 to 3, an elastic sheet 14 made of a thin plate-like synthetic resin material or the like as an elastic body has a base end fixed to an upper portion of the curved guide 12 and a front end thereof. It extends toward the 13B side. Then, the elastic sheet 14 is always held in a substantially horizontal state as shown by the solid line in FIG. 1, and the sheet P is bent and inverted together with the bending guide 12 and fed between the sheet guides 13A and 13B.

Further, when the elastic sheet 14 receives a pressing force from the inner surface side thereof, as shown by the chain line in FIG. 1, the elastic sheet 14 is curved outwardly against its elasticity. By bending the end of the paper guide 13B on the side of the bending guide 12 outward, a space is formed above the elastic sheet 14 to allow the outward bending movement of the sheet 14. A bending allowance portion F for allowing the bending of the paper P is formed between the curved elastic sheet 14 and the bent portion of the paper guide 13B.

The sensor 19 is arranged in the middle of the paper guides 13A and 13B, detects the front end of the paper P passing between the paper guides 13A and 13B, and outputs a detection signal. The guide roller 20 brings the paper P from the feed roller 16 into close contact with the photosensitive drum 2, and the transfer device 21 gives a predetermined potential to the close contact portion, and the difference between the potential and the potential of the toner image is detected. Based on this, the toner image is transferred onto the paper P.

The static elimination lamp 22 exposes the outer peripheral surface of the photosensitive drum 2 after transfer to eliminate static electricity. The cleaning brush 23 removes the paper dust and the like adhering to the photosensitive drum 2 after the transfer. The memory removal brush 24, which is a conductive brush, disturbs the toner T remaining on the photosensitive drum 2 after transfer and uniformly disperses the toner T on the photosensitive drum 2. The developing device 6 also performs a cleaning operation in parallel with the developing operation, in which the residual toner T dispersed by the memory removing brush 24 is collected by electrostatic attraction.

The heat fixing device 25 is arranged on the downstream side of the photosensitive drum 2, and has a heating roller 26 and a pressure roller 27 that comes into contact with the heating roller 26 with a paper transfer path interposed therebetween. Then, the paper P is sent between the heating roller 26 and the pressure roller 27 through the paper guide 28, and the toner image on the paper P is heated and fixed. The paper P on which the image fixing is completed is discharged onto the paper discharge tray 31 via the paper guide 29 and the pair of guide rollers 30.

Next, the circuit configuration of the components related to the sheet feeding operation of the image forming apparatus will be described. As shown in FIG. 4, a CPU (Central Processing Unit) 41 has a ROM (Read Only Memory) 42 that stores a program for controlling the operation of the entire device, and a RAM (Random Access) that temporarily stores various information. A memory) 43 and a timer 44 are connected. Further, the CPU 41 is supplied with a sheet detection signal from the sensor 19 and an operation command signal from the outside. Further, the CPU 41 outputs an operation or stop signal to the drive motor 45 and the electromagnetic clutches 11 and 17 via drivers 48, 49 and 50, respectively.

When an operation command signal is input from the outside, the CPU 41 turns off the electromagnetic clutch 17 based on the program stored in the ROM 42 to disconnect the drive motor 45 from the drive roller 16a. At the same time, the drive motor 45 is operated to rotate the paper feed roller 10 to feed the paper P in the paper feed cassette 9 one by one.

When the front edge detection signal of the paper P is input from the sensor 19 after the rotation of the drive motor 45 is started, the CPU 41 activates the timer 44, and after a predetermined time set by the timer 44 elapses, the electromagnetic wave is generated. The clutch 11 is turned off, and the connection between the drive motor 45 and the paper feed roller 10 is disengaged. That is, the drive of the paper feed roller 10 is stopped after a lapse of some time after the front end of the paper P that has passed the sensor 19 reaches the stopped feed roller 16. Therefore, the sheet P is blocked between the drive roller 16a and the driven roller 16b.

Further, the CPU 41 turns on the electromagnetic clutch 17 to connect the drive motor 45 and the drive roller 16a after a further predetermined time set by the timer 44 has elapsed. That is, the sheet P is blocked between the driving roller 16a and the driven roller 16b, the transport operation is temporarily stopped, and then the sheet P is fed to the image forming portion corresponding to the lower portion of the photosensitive drum 2 by the rotation of the feed roller 16.

Next, the operation of the image forming apparatus configured as described above will be described. Now, at the time of sheet feeding of this image forming apparatus, the operation shown in the flowchart of FIG. 5 is performed under the control of the CPU 41. That is, first, in the operation stop state of the apparatus, both electromagnetic clutches 11 and 17 are turned on, and the drive motor 45 is connected to the paper feed roller 10 and the drive roller 16a. When an operation command signal is input from the outside, the electromagnetic clutch 17 is turned off, the connection between the drive motor 45 and the drive roller 16a is disengaged, the drive motor 45 is operated, and the paper feed roller 10 is rotated. Then, the sheets P in the sheet feeding cassette 9 are fed one by one (steps S1 to S3).

Then, as shown in FIG. 2, the fed sheet P is curved and inverted by the curved guide 12 and the elastic sheet 14, and passes between the sheet guides 13A and 13B. At this time, the elastic sheet 14 is not curved outwardly, and the bending allowance portion F is not formed between the elastic sheet 14 and the bent portion of the paper guide 13B. That is, the sheet P is smoothly guided to the feed roller 16 side by the elastic sheet 14 without passing through the bending allowance part F, and the front end of the sheet P is caught in the bending allowance part F, which causes a jam. Never.

When the front edge of the paper P is detected by the sensor 19, the timer 44 is activated, and after a predetermined time set by the timer 44 has elapsed, the electromagnetic clutch 11 is turned off and the drive motor 45 and The connection with the paper feed roller 10 is released (steps S4 to S7).

That is, the drive of the paper feed roller 10 is stopped after a lapse of some time after the front end of the paper P passing through the sensor 19 reaches the feed roller 16 in the stopped state. Therefore, the paper P is blocked between the drive roller 16a and the driven roller 16b. Therefore, the sheet P is slightly squeezed between the rollers 16a and 16b due to its elastic force, and is bent between the sheet feed roller 10 and the feed roller 16.

Further, at this time, the bending of the sheet P acts as a pressing force on the inner surface of the guide member on the outer peripheral side, that is, the curved guide 12, the elastic sheet 14, and the sheet guide 13B. Then, due to the pressing force, the elastic sheet 14 is bent outward from the state shown in FIG. 2 against the elasticity of the elastic sheet 14 to the state shown in FIG. 3, and the elastic sheet 14 and the paper guide 13B are bent. A bending permitting portion F corresponding to the bending of the sheet P is formed between the sheet and the sheet. Therefore, the bending allowance portion F absorbs the bending amount of the sheet P.

Therefore, the sheet P bends only in the curved portion of the elastic sheet 14, that is, in the bending allowance portion F, and does not bend in other portions. That is, there is no fear that the bending of the paper P will occur between the paper feed cassette 9 and the bending guide 12, for example.

Next, after a further predetermined time set by the timer 44 has elapsed, the electromagnetic clutch 17 is turned on, and the drive motor 45 and the drive roller 16a are connected (steps S8 to S9). That is, the paper P is fed by the rotation of the feed roller 16, and the paper P is fed to the image forming unit corresponding to the lower portion of the photosensitive drum 2.

At this time, the paper P is bent only in the curved portion of the elastic sheet 14, and is not bent in other portions. Moreover, the elastic sheet 14 presses the bent portion of the paper P from the rear side (the left side in FIG. 3) toward the paper transfer direction side, so that the elastic restoring force of the paper P due to the bending acts in the paper transfer direction. To be done. Therefore, the paper P is smoothly transferred between the guide members 12, 13A, 13B by the rotation of the feed roller 16, there is no possibility of jamming, and the transferred paper P may be wrinkled. Absent.

Further, in this embodiment, since the pressing force due to the bending of the sheet P is absorbed by the bending movement of the elastic sheet 14, the elastic force of the sheet P applied to the portion of the feed roller 16 becomes almost constant, and the sheet P is The amount of bite between the feed rollers 16 is always constant. That is, since the front end stop position of the paper P between the feed rollers 16 is always constant, the time for the paper P to reach the image forming unit after the rotation of the feed rollers 16 is always constant. Therefore, the image forming position on the paper P can be always fixed.

The present invention is not limited to the above-described embodiment, and the configurations of the respective parts may be modified and embodied as follows without departing from the spirit of the present invention. (1) As an elastic body, instead of the elastic sheet 14, a guide plate is supported by a spring so as to be movable outward. In this case, the guide plate may be provided so as to be rotatable, or the guide plate may be provided so as to be movable in the vertical direction in FIG. (2) The arrangement position of the elastic sheet 14 should be changed appropriately within the range of the guide members 12, 13A, 13B. (3) The image forming unit should be embodied as something other than the electrophotographic recording system, such as a thermal transfer recording system or an inkjet recording system.

[0037]

[Effect of device]

 As described above in detail, according to the present invention, even if the paper is bent between the paper feed roller and the feed roller, smooth feeding of the paper is not hindered and wrinkles are generated on the paper. The excellent effect of being able to prevent is exhibited.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment in which a sheet feeding device of the present invention is embodied in an image forming apparatus.

FIG. 2 is a partial cross-sectional view showing an elastic sheet in an enlarged manner.

FIG. 3 is a partial cross-sectional view showing, in an enlarged manner, a state in which the elastic sheet is curvedly moved.

FIG. 4 is a block circuit diagram showing a circuit configuration of components related to a sheet feeding operation of the image forming apparatus.

FIG. 5 is a flowchart illustrating an operation of the image forming apparatus when feeding a sheet.

FIG. 6 is a partial cross-sectional view showing a conventional sheet feeding device.

[Explanation of symbols]

9 ... Paper feed cassette, 10 ... Paper feed roller, 12 ... Curved guide forming guide member, 13A ... Paper guide forming guide member, 13B ... Paper guide forming guide member, 14 ... Elastic sheet as elastic body , 16 ... Feed roller, F ... Bending allowance portion, P ... Paper.

Claims (1)

[Scope of utility model registration request] 1. A guide member, comprising: a paper feed roller that feeds sheets of paper stacked and accommodated in a paper feed cassette one by one; and a guide member that bends the fed paper sheets and guides them between a pair of feed rollers. In the middle of the member, an elastic body that always guides the paper to the feed roller side, moves by the pressing force from the paper to allow the paper to bend, and causes the elastic restoring force of the paper due to the flexure to act in the paper transport direction. Paper feeding device.