JP2010023956A - Paper feed apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feed apparatus in which double-feed of paper does not occur. <P>SOLUTION: When a half-moon roller 34 is rotary-driven in a counterclockwise direction together with an auxiliary roller 36, the auxiliary roller 36 is brought into press-contact with a surface of a topmost sheet of paper, and the auxiliary roller 36 pushes down a bundle of paper on a bottom plate 31 against an urging force of a spring, while rolling on the surface of the topmost sheet of paper. Since elastic deformation of the auxiliary roller 36 or deflection of the surface of the topmost sheet of paper occur a little bit at that time, a portion of a large curvature radius R of a half-circumferential face 34a closer to the auxiliary roller 36 than a position 34p is brought into press-contact with the surface of the topmost sheet of paper. While the portion of the large curvature radius R of the half-circumferential face 34a is brought into press-contact with the surface of the topmost sheet of paper, the auxiliary roller 36 is also brought into press-contact with the surface of the topmost sheet of paper. Therefore, stiction between the topmost sheet of paper and the next lower sheets is reduced, and only the topmost sheet of paper is easily drawn out by the half-circumferential face 34a of the large curvature radius R of the half-moon roller 34. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a paper feeding device that is applied to an image forming apparatus such as a copying machine, a printer, or a facsimile machine and feeds recording paper or the like.

  As this type of conventional paper feeding device, there is one disclosed in Patent Document 1. Here, each sheet is accommodated in a state in which the bottom plate on which a plurality of sheets are stacked and accommodated is urged upward and the uppermost sheet is abutted against the height regulating member. Then, the half-moon roller disposed above each sheet is rotated, the half-circular surface of the half-moon roller is pressed against the uppermost sheet, and the uppermost sheet is pulled out by the half-circumferential surface of the half-moon roller.

  Further, in Patent Document 2, an auxiliary roller is attached to the end of the half-moon surface of the half-moon roller, the half-moon roller is rotated, and the half-moon surface of the half-moon roller is pressed against the uppermost sheet. The uppermost sheet is pulled out by the surface, and when the half-circumferential surface of the half-moon roller is separated from the uppermost sheet, an auxiliary roller that rotates together with the half-moon roller is pressed against the uppermost sheet, thereby pushing down each sheet.

  Furthermore, there is a conventional apparatus as shown in FIG. In this apparatus, an auxiliary roller 202 is provided in the vicinity of the end portion 201 a of the semicircular surface of the half-moon roller 201. Then, the half-moon roller 201 is rotated as shown in FIG. Thus, the uppermost sheet 204 is pulled out by the half-circumferential surface of the half-moon roller 201 while the uppermost sheet 204 is separated downward from the height regulating member 203 by pushing down each sheet.

Thus, various conventional apparatuses using a half-moon type roller have been provided.
Japanese Patent Laid-Open No. 62-191337 JP-A-5-286585

  By the way, in the conventional apparatus of FIG.7 and FIG.8, since the angle | corner of 90 degree | times is formed in the half-circumferential surface edge part 201a of the half-moon type roller 201, and the half-circumferential surface edge part 201a falls sharply, the auxiliary | assistant roller 202 When the half-circumferential surface of the half-moon roller 201 is sequentially pressed against the uppermost sheet 204, the time required for both the half-circumferential surfaces of the auxiliary roller 202 and the half-moon roller 201 to contact the uppermost sheet 204 is extremely short. At substantially the same time as 202 separates from the uppermost sheet 204, the corners of the half-circumferential end 201 a of the half-moon roller 201 are pressed against the uppermost sheet 204. At this time, the uppermost sheet 204 remains stationary, and the uppermost sheet 204 is locally pressed by the corners of the half-circumferential end portion 201a of the half-moon roller 201, so that the uppermost sheet 204 and the lower layer sheet 204 are underneath. The static friction force between the sheets becomes very large. For this reason, when the uppermost sheet 204 is pulled out by the half-circumferential surface of the half-moon roller 201, a sheet double feed occurs in which the sheet below it is also pulled out at the same time.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and provides a paper feeding device in which double feeding of paper does not occur in a configuration in which an auxiliary roller is provided at a half circumferential surface end of a half moon type roller. For the purpose.

  In order to solve the above problems, the present invention includes a half-moon roller disposed above a plurality of stacked sheets, and an auxiliary roller provided along one end portion of the half-circumferential surface of the half-moon roller. Then, with each sheet urged upward and with the uppermost sheet in contact with the height regulating member, the half-moon roller is rotated so that the semicircular surfaces of the auxiliary roller and the half-moon roller are on the uppermost layer. In the paper feeding device that sequentially presses against the paper and pushes down each paper by the half-circumferential surface of the auxiliary roller or half-moon type roller, and pulls out the uppermost sheet by the half-circumferential surface of the half-moon type roller, one end of the half-circular surface of the half-moon roller is It is spaced apart from the auxiliary roller, and the curvature of one end of the half circumferential surface is gradually increased as it approaches the auxiliary roller.

  According to the present invention having such a configuration, one end of the semicircular surface of the half moon roller is separated from the auxiliary roller, and the curvature of the one end of the semicircular surface is gradually increased toward the auxiliary roller. The half-circumferential edge of the half-moon roller begins to be gradually pressed against the top-layer paper before the paper is separated from the top-layer paper, and both the half-circumferential edge of the auxiliary roller and the half-moon roller are on the top-layer paper. Longer contact time. For this reason, the upward biasing force of each sheet is received in a distributed manner at the end portions of the semicircular surfaces of the auxiliary roller and the half-moon roller, and the static frictional force between the uppermost sheet and the sheet below it is reduced. In this state, the uppermost sheet is started to be pulled out by the end portion of the half-circumferential surface of the half-moon roller, and only the uppermost sheet is quickly pulled out, making it difficult for the sheets to be double fed.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view showing an image forming apparatus to which an embodiment of a paper feeding device of the present invention is applied. This image forming apparatus acquires image data read from a document, or acquires image data received from the outside, and forms a monochrome image indicated by the image data on a sheet. Broadly speaking, it is composed of a document transport unit (ADF) 101, a document reading device 102, a printer unit 103, a paper transport unit 104, and a paper feed device 105.

  When at least one document is set on the document setting tray 11, the document conveying unit 101 pulls out the document one by one from the document setting tray 11 and conveys the document. The document is read by the first platen glass 14 of the document reading device 102. The document is guided upward and discharged, and the document is discharged to the discharge tray 12.

  In the document reading apparatus 102, an optical unit including a first scanning unit 15 and a second scanning unit 16 is disposed below the first platen glass 14, and when the document passes over the first platen glass 14, The document surface is exposed by the light source of the first scanning unit 15, the reflected light from the document surface is guided to the imaging lens 17 by the mirrors of the first and second scanning units 15 and 16, and the image of the document surface by the imaging lens 17. Is imaged on a CCD (Charge Coupled Device) 18. The CCD 18 repeatedly reads an image on the document surface in the main scanning direction and outputs image data indicating the image on the document surface.

  Further, when the document is placed on the second platen glass 19 on the upper surface of the document reading apparatus 102, the first scanning unit 15 moves the first and second scanning units 15 and 16 in the sub-scanning direction, and the second scanning unit 15 performs the second scanning. The document surface on the platen glass 19 is exposed, the reflected light from the document surface is further reflected by the first and second scanning units 15 and 16, and guided to the imaging lens 17. Is imaged on the CCD 18. At this time, the first and second scanning units 15 and 16 are moved while maintaining a predetermined speed relationship with each other, and the reflection of the document surface → the first and second scanning units 15 and 16 → the imaging lens 17 → the CCD 18 is reflected. The positional relationship between the first and second scanning units 15 and 16 is always maintained so that the length of the light path of the light does not change, and thereby the focus of the image on the document surface on the CCD 18 is always maintained accurately. Yes.

  The image data output from the CCD 18 is subjected to various types of image processing by a control circuit such as a microcomputer and then output to the printer unit 103.

  Therefore, in the document reading apparatus 102 according to the present embodiment, the document is transported on the first platen glass 14 and the document is placed on the second platen glass 19, and the optical unit (first and second). Both of the document fixing methods in which the scanning units 15 and 16) are moved are also used.

  In the printer unit 103, the photosensitive drum 4 is disposed substantially at the center, and a charging unit 5, an optical scanning unit 6, a developing unit 7, a transfer unit 8, and a cleaning unit 9 are disposed around the photosensitive drum 4.

  The charging unit 5 uniformly charges the surface of the photosensitive drum 4. The optical scanning unit 6 inputs image data, scans the light beam on the uniformly charged photosensitive drum 4 while modulating the intensity of the light beam according to the image data, and writes an electrostatic latent image. The developing unit 7 visualizes the electrostatic latent image on the photosensitive drum 4 with a developer, and forms a developer image on the photosensitive drum 4. The transfer unit 8 transfers the developer image on the photoconductive drum 4 onto the paper while sandwiching and conveying the paper with the photoconductive drum 4. The cleaning unit 9 removes the developer remaining on the photosensitive drum 4 so that a new developer image can be formed on the photosensitive drum 4.

  A fixing device 20 is disposed above the printer unit 103. The fixing device 20 receives the paper on which the image has been transferred and sandwiches it between the fixing roller and the pressure roller to fix the developed image transferred on the paper.

  This sheet is conveyed upward by the conveying roller and discharged from the discharge roller 21 to the discharge tray 22.

  When images are formed on both sides of the paper, the paper is reversely conveyed in the reverse direction by the paper discharge roller 21, further conveyed to the reverse conveyance path 23, and the front and back of the paper are reversed to the printer unit 103. It is conveyed again, and the developer image is transferred and fixed on the back surface thereof. Then, the paper is discharged from the paper discharge roller 21 to the paper discharge tray 22.

  The paper feeding device 105 includes a paper feeding cassette 24, and the paper is separated and supplied one by one from the paper feeding cassette 24, and the paper is supplied between the photosensitive drum 4 and the transfer unit 8. The developer image on the drum 4 is transferred.

  Next, the configuration of the sheet feeding device 105 according to the present embodiment will be described in detail with reference to FIG. In the paper feeding device 105, the paper feeding cassette 24 is slidably supported on the front side of the main body of the image forming apparatus, and the paper feeding cassette 24 is pulled out to the front side so as to be placed on the bottom plate 31 inside the paper feeding cassette 24. A sheet bundle is loaded and accommodated. A rear end regulating member 32 is provided at the bottom of the paper feed cassette 24 so as to be movable left and right in FIG. 2. The front end of the sheet bundle on the bottom plate 31 abuts against the inner wall surface 24 a of the paper feed cassette 24. The trailing edge restricting member 32 is moved until it contacts the trailing edge of the sheet bundle on the bottom plate 31, and the sheet bundle on the bottom plate 31 is sandwiched between the inner wall surface 24a and the trailing edge restricting member 32 and positioned. . Further, both sides of the sheet bundle are positioned by being sandwiched by a pair of guide members (not shown) provided movably on the bottom of the sheet feeding cassette 24.

  Further, the bottom plate 31 is pivotally supported by a shaft 31 a and is urged counterclockwise around the shaft 31 a by a spring (not shown), so that the uppermost sheet 25 on the bottom plate 31 contacts the height regulating member 33. The sheet bundle on the bottom plate 31 is lifted until it comes into contact.

  The half-moon roller 34 is disposed on the upper end side of the bottom plate 31 and is pivotally supported, and is rotated about the shaft 35 in the counterclockwise direction. An auxiliary roller 36 is attached to one end portion of the semicircular surface of the half-moon roller 34.

  When the half-moon roller 34 is driven to rotate in the counterclockwise direction, the auxiliary roller 36 first comes into pressure contact with the uppermost sheet 25 on the bottom plate 31, and the auxiliary roller 36 rolls on the uppermost sheet 25 while moving on the bottom plate 31. This sheet bundle is pushed down against the biasing force of the spring, and the uppermost sheet 25 is separated downward from the height regulating member 33. Subsequently, the semicircular surface of the half-moon roller 34 comes into pressure contact with the uppermost sheet 25, and the uppermost sheet 25 is pulled out by the semicircular surface of the semimoon-shaped roller 34.

  Similarly, every time the half-moon roller 34 makes one rotation in the counterclockwise direction, the uppermost sheet 25 is pushed away from the height restricting member 33 by the auxiliary roller 36, and the half-circumferential surface of the half-moon roller 34 is Sheet 25 is pulled out.

  FIG. 3 is an enlarged sectional view showing the periphery of the half-moon roller 34. FIG. 4 is a cross-sectional view showing a state in which the half-moon roller 34 is rotated approximately 90 degrees counterclockwise. Further, FIG. 5 is a cross-sectional view showing one end portion of the half-moon roller 34 and the periphery of the auxiliary roller 36 in an enlarged manner.

  As shown in FIGS. 3 to 5, the half-moon roller 34 includes a frame body 41 and a friction rubber 42, fixes the frame body 41 to the shaft 35, and superimposes the friction rubber 42 on the semicircular surface of the frame body 41. Thus, both ends 42 a of the friction rubber 42 are hooked and fixed to the respective engagement recesses 41 a on both sides of the frame body 41. The outer surface of the friction rubber 42 is a half circumferential surface 34a of the half moon roller 34, and a part of the friction rubber 42 is one end 34b of the half circumferential surface 34a.

  A rotatable auxiliary roller 36 is connected to one end portion 41 b of the frame body 41 by a connection structure (not shown), and the auxiliary roller 36 is spaced from the one end portion 34 b of the half-moon roller 34.

  In FIG. 5, the semicircular surface 34a of the half-moon roller 34 draws an arc centered on the shaft 35 (shown in FIGS. 3 and 4) except for one end 34b of the semicircular surface 34a. Further, the outermost peripheral position 36p of the auxiliary roller 36 is on or near the rotational track S of the semicircular surface 34a of the half-moon roller 34 that rotates about the shaft 35.

  Assuming that one end 34b (a part of the friction rubber 42) of the semi-circumferential surface 34a is on the right side of the position 34p, the semi-circumferential surface 34a draws an arc centering on the shaft 35 on the left side of the position 34p. One end 34b of 34a is formed so that its curvature R gradually increases as it approaches the auxiliary roller 36 on the right side of the position 34p and is wound inside.

  When such a half-moon type roller 34 is rotated counterclockwise together with the auxiliary roller 36, the auxiliary roller 36 comes into pressure contact with the uppermost sheet surface 25a as described above, and the auxiliary roller 36 is in the uppermost layer. The sheet bundle on the bottom plate 31 is pushed down against the biasing force of the spring while rolling on the sheet surface 25a.

  At this time, since the uppermost sheet is urged upward and is always pressed against the half-moon roller 34 or the auxiliary roller 36, the half-moon roller 34 and the upper-layer sheet surface 25a as shown in FIG. The auxiliary roller 36 is displaced. In FIG. 6, a solid line indicates a state in which only the auxiliary roller 36 is in pressure contact with the uppermost sheet surface 25a, and a dotted line indicates one end 34b of the semicircular surface 34a of the half-moon roller 34 and the auxiliary roller 36 is the uppermost sheet surface 25a. Further, a two-dot chain line shows a state in which only the half circumferential surface 34a of the half moon roller 34 is in pressure contact with the uppermost sheet surface 25a.

  As is apparent from FIG. 6, before the auxiliary roller 36 is separated from the uppermost sheet surface 25a, the one end 34b having a large curvature R of the half circumferential surface 34a comes into pressure contact with the uppermost sheet surface 25a.

  Then, the half-circumferential surface 34a is rotated until the half-circular roller 34 rotates further, the semi-circumferential surface 34a on the left side of the position 34p presses against the uppermost sheet surface 25a, and the auxiliary roller 36 is separated from the uppermost sheet surface 25a. One end 34b having a large curvature R of 34a continues to press against the uppermost sheet surface 25a.

  Therefore, for a predetermined period before the auxiliary roller 36 is separated from the uppermost sheet surface 25a, the one end portion 34b having a large curvature R of the half circumferential surface 34a continues to be in pressure contact with the uppermost sheet surface 25a.

  Since the auxiliary roller 36 is also in pressure contact with the uppermost sheet surface while the one end 34b having a large curvature R of the half peripheral surface 34a continues to be in pressure contact with the uppermost sheet surface, the half circumference with respect to the uppermost sheet surface. The pressure contact area between the surface 34a and the auxiliary roller 36 is widened, the urging force of the spring that pushes up the sheet bundle on the bottom plate 31 is dispersed, and the pressure contact force of the one end 34b of the half circumferential surface 34a with respect to the uppermost sheet surface is reduced. Therefore, the static frictional force between the uppermost sheet and the lower sheet is reduced, and the uppermost sheet is easily separated from the lower sheet by the one end portion 34b of the half circumferential surface 34a. Will start immediately. Then, immediately after the start of conveyance, only a small dynamic friction force is generated between the uppermost sheet and the lower sheet, so that the uppermost sheet is reliably pulled out by the half circumferential surface 34a of the half-moon roller 34. . As a result, only the uppermost sheet is pulled out, and there is no need for double feeding of sheets.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood.

  For example, the degree of increase in the curvature R of the one end 34b of the half-moon roller 34 may be changed as appropriate. Further, the present invention can be applied not only to a paper feed tray for stacking and storing printing paper but also to a document tray for stacking and storing original paper.

1 is a cross-sectional view illustrating an image forming apparatus to which an embodiment of a paper feeding device of the present invention is applied. It is sectional drawing which shows the paper feeder of this embodiment. FIG. 3 is an enlarged cross-sectional view showing the vicinity of a half moon type roller in the paper feeding device of FIG. 2. FIG. 3 is a cross-sectional view showing a state where a half-moon roller in the paper feeding device of FIG. 2 is rotated approximately 90 degrees counterclockwise. It is sectional drawing which expands and shows the one end part of a half moon type roller, and an auxiliary roller periphery more. It is a figure which shows the displacement process of the paper surface of the uppermost layer with respect to a half moon type roller and an auxiliary | assistant roller. It is sectional drawing which expands and shows the half-moon type | mold roller periphery in the conventional paper feeder. FIG. 8 is a cross-sectional view illustrating a state in which a half-moon roller in the sheet feeding device illustrated in FIG. 7 is rotated approximately 90 degrees counterclockwise.

Explanation of symbols

11 Document Set Tray 12 Paper Discharge Tray 20 Fixing Device 21 Paper Discharge Roller 24 Paper Feed Cassette 31 Bottom Plate 32 Rear End Restricting Member 33 Restricting Member 34 Half-Moon Roller 36 Auxiliary Roller 101 Document Conveying Unit (ADF)
102 Document Reading Device 103 Printer Unit 104 Paper Conveying Unit 105 Paper Feeding Device

Claims (1)

A half-moon roller disposed above a plurality of stacked sheets, and an auxiliary roller provided along one end of the half-circumferential surface of the half-moon roller, and urges each sheet upward, With the uppermost sheet in contact with the height regulating member, the half-moon roller is rotated, and the auxiliary roller and the half-moon surface of the half-moon roller are sequentially pressed against the uppermost sheet, and the auxiliary roller or the half-moon roller In the paper feeding device that pulls out the uppermost sheet by the half circumference surface of the half moon type roller while pushing down each sheet by the half circumference surface,
One end portion of the half-circumferential surface of the half-moon roller is separated from the auxiliary roller, and the curvature of the one end portion of the half-circular surface is gradually increased toward the auxiliary roller.

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