JP2006151669A - Paper discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism that achieves both alignment on a stacking tray during sheet discharge and curling of a sheet material.
Disclosed is a paper discharge device that achieves both alignment on a stacking tray during paper discharge and curling of a sheet material. Both of them are rotationally driven, and a plurality of conveying rollers whose sum of radii of each roller is larger than the axial distance between the rollers are alternately arranged in the axial direction, and the sheet material is nipped and conveyed by a group of spaced rollers. In a pair of paper discharge rollers, an elastic conveyance roller is attached to both ends of one paper discharge roller, and a roller is attached to the opposite part of the other paper discharge roller so as to freely rotate with respect to the roller shaft, thereby forming a nip. A pair of paper discharge rollers is provided.
[Selection] Figure 7

Description

  The present invention relates to a paper discharge device of an image forming apparatus.

  As an example of the prior art, a printer which is an image forming apparatus that records an image on a sheet material using an electrophotographic process will be described with reference to FIG. FIG. 1 is a diagram illustrating a printer main body.

  The operation of the printer P will be described below.

  First, face-down paper discharge for single-sided printing will be described.

  As the sheet feeding roller 2 rotates, the sheet material S is fed from the sheet feeding cassette 1 one by one in the sheet feeding direction, and is conveyed to the registration roller pair 4 through the intermediate roller pair 3.

  The sheet material S is sent between the photosensitive drum 6 and the transfer roller 7 built in the toner cartridge 5 constituting the image forming means by the registration roller pair 4 rotating at a predetermined timing.

  A latent image is formed on the photosensitive drum 6 by laser light from the laser scanner unit 8, and the toner image is developed on the photosensitive drum 6 by attaching toner to the latent image. Then, the toner image on the photosensitive drum 6 is transferred to the sheet material S by the transfer roller 7.

  After the transfer of the toner image, the sheet material S is sent to the fixing device 9 by the conveying force of the photosensitive drum 6 and the transfer roller 7, where the toner image on the sheet material S is fixed. After the fixing, the sheet material S is stacked on the stacking tray 11 through the paper discharge roller pair 10.

  Next, the configuration of the paper discharge roller pair 10 will be described. First, as a configuration generally employed as a pair of paper discharge rollers, there is a type in which a nip is formed by a conveying rubber roller and a biased roller. This is shown in FIG. 2 which is a schematic sectional view of the paper discharge unit of the printer 1. A sheet discharge roller 13 is disposed in a position in which the sheet discharge roller 13 is incorporated in the roller holder 17 at a position facing the sheet discharge roller 12, and is upwardly moved by a roller spring 14 having one end engaged with the roller holder 17 and the other end engaged with the sheet discharge frame 16. Energize. Two to six combinations of such rollers and rollers are arranged in the axial direction to constitute a pair of conveying rollers. On the other hand, the pair of discharge rollers configured as described above can stably convey, but after the nip of the discharge roller pair 10 along the discharge guide 15, the leading end of the discharged sheet material bows to the stacking tray 11 in the DA direction. There is a problem that the sheet material is rounded on the stacking tray 11 and the alignment is disturbed.

  In order to solve this problem, a roller configuration in which the paper discharge rollers are arranged in a comb shape as shown in FIGS. FIG. 3 is a schematic cross-sectional view of a paper discharge section having a comb-teeth configuration, and FIG. The paper discharge upper roller 18 presses the rubber roller portion 18a into the paper discharge upper roller shaft 18b, and the paper discharge lower roller 19 similarly presses the rubber roller portion 19a into the paper discharge lower roller shaft 19b. The paper discharge upper roller 18 and the paper discharge lower roller 19 are respectively provided with a paper discharge upper gear 20 and a paper discharge lower gear 21 and are driven both vertically. A plurality of upper and lower rubber rollers are alternately arranged at equal intervals on the comb teeth so as to overlap by the interval Ga. At this time, the gap Ga between the upper and lower rubber rollers is (φ18a + φ19a) / 2−La using the diameter φ18a of the upper discharge roller, the diameter φ19a of the lower discharge roller, and the center distance La between the upper discharge roller 18 and the lower discharge roller 19. It is expressed and is usually about 1 to 3 mm. Further, since both the paper discharge upper roller 18 and the paper discharge lower roller 19 have conveying force, the diameter φ18a of the paper discharge upper roller, the diameter φ19a of the paper discharge lower roller, the number of teeth of the paper discharge upper gear 20 and the paper discharge lower gear 21 are adjusted. Thus, the transport speeds v18a and v19a of the paper discharge upper roller 18 and the paper discharge lower roller 19 are made equal.

  With the above configuration, the sheet material S is conveyed without forming a nip with rollers and rollers. Then, the discharged sheet material S is rubbed in the transport direction like Sa, so that the discharge direction DB is straightened, the leading edge of the sheet material on the stacking tray 11 is prevented from being rounded, and the alignment property is improved. It becomes possible.

As another conventional example, for example, Patent Document 1 and Patent Document 2 can be cited.
JP 2003-118910 A JP 2002-068555 A

  However, the conventional comb-toothed paper discharge roller pair has the following problems. First, the curl that can be formed on the sheet material will be described. The sheet material is curled mainly by the fixing process. When the sheet material is loaded on the stacking tray, the left and right edges of the sheet material are curled upward as shown in FIG. 5A depending on the type of the sheet material and the configuration of the fixing device. 5 (b), the front and rear ends of the sheet material are curled upward, the left and right ends of the sheet material are curled downward, as shown in FIG. 5 (c), and the sheet as shown in FIG. 5 (d). The front and rear ends of the material are roughly divided into those that curl downward. Since the sheet material curled downward in FIGS. 5C and 5D is crushed when it is stacked on the stacking tray, there is no adverse effect on the alignment property, and there is no problem as long as the curl amount is not so large. The sheet material curled upward in FIGS. 5 (a) and 5 (b) has an adverse effect on alignment because the curl is not crushed on the stacking tray. 5 (a), the sheet material is rubbed in the conveying direction in the arrangement of the comb teeth shown in FIGS. 3 and 4, and the left and right end curls are further promoted. There was a drawback that worsened the curl.

  The present invention has been devised for the purpose of solving the above-described problems, and it is an object of the present invention to provide a mechanism that achieves both alignment on a stacking tray during sheet discharge and curling of a sheet material.

  In order to achieve the above object, a typical configuration of a sheet discharge device that achieves both alignment on the stacking tray and sheet material curl at the time of sheet discharge of the image forming apparatus according to the present invention is driven and rotated together. A pair of paper discharge rollers in which a plurality of conveying rollers whose sum of radii of each roller is larger than the distance between the axes of each roller are alternately arranged in the axial direction, and the sheet material is nipped and conveyed by a group of spaced rollers. In this case, an elastic conveying roller is attached to both ends of one of the paper discharge rollers, and a roller is attached to the opposite portion of the other paper discharge roller so as to freely rotate with respect to the roller shaft. It is characterized by having.

  As described above, in the first and second embodiments of the present invention, the rollers at the center of the paper discharge roller pair are arranged in a comb-like shape, and the end is formed with a rubber roller and a mold roller. By configuring, it is possible to correct the curl that occurs at the left and right edges of the sheet material without discharging the sheet material straight and without disturbing the alignment to the stacking tray. become.

  Next, the present invention will be described based on the illustrated embodiment.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a schematic cross-sectional view of a paper discharge device of a laser beam printer as an example of the image forming apparatus, and FIG. 7 is an arrow view of the paper discharge device from the RS direction. 6 shows an S1-S1 cross section in FIG. FIG. 8 shows a cross-sectional view of the center lower roller 31a described later.

  Reference numeral 30 denotes a discharge upper roller, which is composed of a central upper roller 30a, an end upper roller 30b, an intermediate upper roller 30c, and a discharge upper roller shaft 30d. The central upper roller 30a and end upper roller 30b are upper discharge rollers. Fixed to the roller shaft 30d, the middle upper roller 30c idles. Reference numeral 31 denotes a lower discharge roller 31a, a lower roller at the center of 31a, a lower roller at the end of 31b, an intermediate lower roller at 31c, a lower roller shaft 31d, and a lower roller 31a at the center fixed to the upper roller shaft 31d. The subordinate roller 31b and the intermediate lower roller 31c idle. CL is a center line. In this printer, sheet materials of all sizes are conveyed with reference to CL, and the rollers and rollers of the paper discharge upper roller 30 and paper discharge lower roller 31 are arranged symmetrically with respect to CL. The diameter φ30 of the center upper roller 30a and the end upper roller 30b is the same and is approximately φ12 to 20 mm. Further, the diameter φ31 of the center lower roller 31a and the end lower roller 31b are the same and are approximately φ12 to 20 mm. In v30 and v31, the roller diameters φ30 and φ31, the gear upper 32, and the gear lower 33 are adjusted so that v30 = v31 is the conveyance speed of the paper discharge upper roller 30 and paper discharge lower roller 31, respectively. Reference numerals 34 and 35 respectively receive the paper discharge upper roller shaft 30d and the paper discharge upper roller shaft 31d on the paper discharge bearing and below the paper discharge bearing, respectively. L is the distance between the axes of the upper discharge roller 30 and the lower discharge roller 31. The nip N is formed by setting the inter-axis distance L to (φ30 + φ31) / 2 <L, and the end upper roller 30b is crushed by forming the end upper roller 30b from rubber and the end lower roller 31b from mold. As shown in FIG. 6, an upwardly curved nip is formed. The combination of the center upper roller 30a and the middle lower roller 31c, and the combination of the middle upper roller 30c and the center lower roller 31a are provided with a slight gap of about 0.2 mm, so that a nip is not formed, and the sheet material is gently guided. The behavior of sheet material is regulated. The overlap amount created by the central upper roller 30a and the central lower roller 331a is about 1 to 3 mm as in the prior art. Reference numeral 31a ′ denotes a knurling cut by the central lower roller 31a, reference numeral 36 denotes an upper discharge guide, and reference numeral WS denotes a span between the outer ends of the upper end roller 30b and the lower end roller 31b. The width of the LEGAL paper is 8.5 inches (215.9 mm), and the width of the WR is preferably 35 mm or more in order to give a curl correction effect by the width of the end upper roller 30b and the end lower roller 31b. SP is approximately 140 mm or less in the span between the end upper rollers 30b.

  Next, the operation of the paper discharge unit will be described. After the fixing process, the sheet material is conveyed along the upper discharge guide 36 and enters the nip N of the discharge roller pair.

  The curl is corrected by rubbing a curl with a stiff line in the conveying direction on the left and right ends of the sheet material shown in FIG. Since the lower end roller 31b is freely rotatable with respect to the lower discharge roller shaft 31d, the sheet material is conveyed at the conveyance speed v30 of the upper discharge roller 30. In the center of the sheet material, the upper and lower rollers are arranged in a comb-like shape as before, so the sheet material is squeezed in the transport direction, and the sheet material is ejected straight and stacked. The alignment does not deteriorate, such as rounding on the tray.

  Further, a knurled 31a ′ is cut in the central lower roller 31a, and the rear end of the sheet material is hooked by a knurled groove at the time of paper discharge so that the rear end of the sheet material remains on the central lower roller 31a. It is preventing. The center lower roller 31a may have any shape other than knurling as long as the rear end of the sheet material can be kicked out.

  Regarding the nip N, the curl correction amount can be adjusted by changing the width of the nip N by changing the diameter of the central upper roller 30a and the rubber hardness. In particular, if the nip amount is increased by using low-hardness rubber, the curl correction effect is also increased.

  As described above, by forming a nip with rollers and driven rollers at both ends of the pair of discharge rollers in the comb-tooth arrangement, the sheet material can be aligned while correcting the curl at the left and right ends. Has the effect of keeping

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a schematic cross-sectional view of the paper discharge device of the laser beam printer, and FIG. 10 is a view as viewed from the direction of the arrow of the paper discharge device. FIG. 9 shows an S2-S2 cross section in FIG. 11a and 11b are views showing the drive gear trains of the present embodiment and the first embodiment, respectively, and are FV arrow views in FIG. A description of the same parts as those in the first embodiment is omitted.

  In the present embodiment, it will be described that the same effect as that of the first embodiment can be obtained by driving the upper conveyance roller of the paper discharge roller pair and driving the lower roller.

  Reference numeral 50 denotes a discharge upper roller, which includes a central upper roller 50a, an upper end roller 50b, an intermediate upper roller 50c, and a discharge upper roller shaft 50d. The upper upper roller 50a and the upper end roller 50b are upper discharge rollers. Fixed to the roller shaft 50d, the intermediate upper roller 50c idles. Reference numeral 51 denotes a lower discharge roller, a lower roller at the center of 51a, a lower roller at the end of 51b, an intermediate lower roller at 51c, a lower roller shaft 51d, and each roller and roller fixed to the upper discharge roller shaft 51d. Alternatively, the discharge lower roller shaft 51d may be made of a mold and integrated with the end lower roller 51b and the intermediate lower roller 51c. 52 is a paper discharge upper gear, 53 is a paper discharge idler gear, 54a and 54b are paper discharge input gears, and 55, 56 and 57 are bearings. φ50a is the diameter of the center upper roller 50a and is the same as the diameter of the end upper roller 550b.

  Next, a method for driving the paper discharge upper roller 50 and the paper discharge lower roller 51 will be described. In the first embodiment, the drive is transmitted in the order of the paper discharge input gear 54b, the paper discharge lower gear 33, and the paper discharge upper gear 32 from a drive gear train (not shown). In this embodiment, the drive is transmitted in the order of the paper discharge input gear 54 a, the paper discharge idler gear 53, and the paper discharge upper gear 52. The nip N formed by the end upper roller 30b and the end lower roller 31b is the same as that of the first embodiment except that the end lower roller 31b is driven. Next, the nip N2 between the central upper roller 50a and the intermediate lower roller 51c will be described. Unlike the first embodiment, a nip is formed between the central upper roller 50a and the intermediate lower roller 51c. The width of the nip N2 is narrower than that of the nip N and has a sheet material conveying force, but does not have the ability to correct curl.

  Next, the operation of the paper discharge unit will be described. As in the first embodiment, the sheet material for which the fixing process has been completed is conveyed along the upper discharge guide 36 and enters the nip N and the nip N2 of the discharge roller pair.

  As in the first embodiment, the curl is corrected by rubbing curls with a stiff line in the conveying direction on the left and right ends of the sheet material shown in FIG. Since the upper and lower rollers are arranged in a comb-like shape at the center of the sheet material as before, the sheet material is squeezed in the transport direction, and the sheet is discharged straight to the paper holding handle, on the stacking tray. The alignment does not deteriorate, such as rounding.

  Next, when transporting a sheet material having a narrow paper width such as an envelope or an index card, the sheet is not sandwiched by the nip N between the upper end roller 30a and the lower end roller 31b at both ends, but between the central upper roller 50a and the intermediate lower roller. It is conveyed and discharged by the nip N2 between the roller 51c. In this way, by driving one of the pair of transport rollers and driving the other, the transport speed is completely the same between the upper and lower rollers, and more stable paper transport is possible.

FIG. 6 is a schematic sectional view of an image forming apparatus showing a conventional technique. FIG. 6 is a schematic cross-sectional view of a paper discharge device showing a conventional technique. FIG. 6 is a schematic cross-sectional view of a paper discharge device showing a conventional technique. The arrow view of the paper discharge apparatus which shows the prior art. FIG. 4 is a diagram illustrating a curl direction of a sheet material generated by a fixing device. 1 is a schematic cross-sectional view of a paper discharge device of a printer showing a first embodiment of the present invention. FIG. 3 is an arrow view of the paper discharge device of the printer showing the first embodiment of the present invention. 1 is a cross-sectional view of a paper discharge roller of a printer showing a first embodiment of the present invention. The schematic sectional drawing of the paper discharge apparatus of the printer which shows 2nd embodiment of this invention. The arrow line view of the paper discharge apparatus of the printer which shows 2nd embodiment of this invention. The figure showing the drive gear train of 2nd embodiment of this invention. The figure showing the drive gear train of a first embodiment of the present invention.

Explanation of symbols

P Laser beam printer S Sheet material 1 Paper feed cassette 2 Paper feed roller 3 Intermediate roller pair 4 Registration roller pair 4
5 Toner cartridge 6 Photosensitive drum 7 Transfer roller 8 Laser scanner unit 9 Fixing device 10 Paper discharge roller pair 11 Stack tray 12 Paper discharge roller 13 Paper discharge roller 14 Roller spring 15 Paper discharge guide 16 Paper discharge frame 17 Roller holder 18 Paper discharge upper roller 18a Rubber roller section 18b Paper discharge upper roller shaft 19 Paper discharge lower roller 19a Rubber roller section 19b Paper discharge lower roller shaft 20 Paper discharge upper gear 21 Paper discharge lower gear Ga Space between rubber rollers of paper discharge upper and lower rollers φ18a Paper discharge upper roller φ19a Paper discharge lower roller La Distance between centers of paper upper and lower rollers v18a Paper discharge upper roller v19a Paper discharge lower roller Sa Sheet sheet RS, FV Arrow direction 30 Paper discharge upper roller 30a Center upper roller 30b End upper roller 30c Middle upper roller 30d Paper upper roller Roller shaft 31 Roller 31a Center lower roller 31a 'Knurled 31b cut at center lower roller 31b End lower roller 31c Intermediate lower roller 31d Discharge lower roller shaft SP Spanned span between upper rollers CL End point of discharge device L Distance between the shafts φ30 Diameter of the upper discharge roller φ31 Diameter of the lower discharge roller N Fixing nip 36 Upper discharge guide 50 Upper discharge roller 50a Upper roller 50b Upper roller 50c Upper roller 50d Upper roller shaft 51 Upper discharge roller shaft 51 Lower discharge roller Roller 51a Center lower roller 51b End lower roller 51c Intermediate lower roller 51d Paper discharge lower roller shaft 52 Paper discharge upper gear 53 Paper discharge idler gear 54a, 54b Paper discharge input gear 55, 56, 57 Bearing φ50a Diameter of upper roller N2 Central portion Nip between upper roller 50a and intermediate lower roller 51c

Claims (7)

Both of them are rotationally driven, and a plurality of conveying rollers whose sum of radii of each roller is larger than the axial distance between the rollers are alternately arranged in the axial direction, and the sheet material is nipped and conveyed by a group of spaced rollers. In a pair of paper discharge rollers,
A pair of paper discharge rollers having a nip formed by attaching elastic conveying rollers to both ends of one paper discharge roller and attaching rollers to the opposite part of the other paper discharge roller so as to freely rotate with respect to the roller shaft. A paper discharge device.   One is a rotational drive and the other is a driven paper discharge roller. An elastic conveying roller is attached to the end of the paper discharge roller that performs rotational drive, and a roller is attached to the end of the opposite driven paper discharge roller. A nip is formed by fixing to the roller shaft, and a plurality of transport rollers whose sum of radii is larger than the distance between the axes of each roller are alternately arranged in the middle of each paper discharge roller. A paper discharge device comprising a pair of paper discharge rollers for nipping and conveying the sheet material by a group of spaced rollers. The paper discharge device according to claim 2, wherein a roller disposed at an end of the driven paper discharge roller is formed integrally with the paper discharge roller shaft.
3. The paper discharge device according to claim 2, wherein   4. The paper discharge apparatus according to claim 1, wherein a roller is attached to an opposite portion of the paper discharge roller, and a gap is provided between the roller and the roller. Paper device.   3. The paper discharge device according to claim 2, wherein a roller is fixed coaxially with the driven paper discharge roller so as to form a nip at an opposite portion of the driven paper discharge roller. In the paper discharge device according to claim 1, a kick-out member for kicking out a rear end of a sheet material is provided on the paper discharge roller.
The paper discharge device according to any one of claims 1 to 5, wherein   An image forming apparatus comprising the paper discharge device according to claim 1.

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