JP2004107042A - Sheet carrier device, paper feeding unit, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet carrier device capable of precisely carrying a sheet in a roll supported under a cantilevered condition, a paper feeding unit, and an image forming device having it. <P>SOLUTION: Since supporting positions are alternately provided respectively, a feed roll 28 and a retard roll 26 can stably carry a sheet with a uniform nip pressure even at a carrier roller part away from a supporting position. Distances of a pair of the carrier roller parts from the supporting positions are made approximately equal, so that a nip pressure can be made approximately equal. Even when the distance from a supporting end to the carrier roller part cannot be adjusted by an inclusion, the retard roll 26 can stably carry the sheet by installing a torque limiter 104 between the supporting position and the carrier roller part 94. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet conveying device for conveying a sheet, a sheet feeding unit for storing the sheet, and an image forming apparatus such as an electrophotographic system having the same.
[0002]
2. Description of the Related Art It is known that a sheet conveying roller is supported in a cantilever state so that a conveying roller provided on the sheet conveying roller can be easily attached and detached. (See Utility Model Document 1)
[0003]
[Utility Model Document 1] Japanese Utility Model Publication No. 7-12352
[Problems to be solved by the invention]
However, when a plurality of transport rollers are pressed against the opposing transport rollers or the like, the rollers far from the support position have a lower contact pressure than the rollers near the support position due to deflection or inclination of the support shaft and are transported. The sheet may be skewed.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet conveying device, a sheet feeding unit, and an image forming apparatus having the same, which can accurately convey a sheet.
[0006]
To achieve the above object, a first feature of the present invention is that a first transport roll supported in a cantilever state and a first transport roll supported in a cantilever state are provided. The first transport roll and the second transport roll include a second transport roll, and the first transport roll and the second transport roll are supported alternately and are in contact with a predetermined contact pressure. Therefore, the sheet can be conveyed at a predetermined contact pressure, so that the sheet can be conveyed accurately.
The first transport roll has a first support shaft and a first roller provided on the first support shaft, and the second transport roll has a second support shaft. It is preferable to have a shaft and a second roller provided on the second support shaft, and the first roller and the second roller are preferably in contact with each other.
[0008] The distance from the first support portion on which the first support shaft is supported to the first roller portion, and the distance from the second support portion on which the second support shaft is supported to the second roller portion. It is preferable that the distance is substantially equal.
It is preferable that the first roller portion and the second roller portion are detachably mounted on the first support shaft and the second support shaft, respectively.
A second feature of the present invention is that a paper feeding unit main body, a paper feeding cassette detachably inserted into the paper feeding unit main body, and a cantilever supported by the paper feeding unit main body. A feed roll, and a retard roll supported in a cantilevered state by the paper feed cassette, wherein the feed roll and the retard roll are alternately supported and come into contact with a predetermined contact pressure It is in. It is preferable that the second transport roll further includes a torque limiter between the second support portion and the second roller portion.
According to a third feature of the present invention, there is provided an image forming apparatus having the above-mentioned sheet feeding unit.
[0012]
Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 has an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 described later is provided above the image forming apparatus main body 12. At the same time, for example, two-stage paper feed units 18 are arranged below the image forming apparatus main body 12. Further, below the image forming apparatus main body 12, there are provided paper feed units 18, 18 which are optionally attached and detached.
Each paper supply unit 18 has a paper supply unit main body 20 and a paper supply cassette 22 for storing paper. The paper feed cassette 22 is slidably mounted on the paper feed unit main body 20, and is pulled out in a front direction (right direction in FIG. 1). Further, a nudger roll 24 is disposed in the upper portion near the inner end of the paper feed cassette 22, and a retard roll 26 and a feed roll 28 are disposed in front of the nudger roll 24. Further, the optional paper feed units 18 are provided with a pair of feed rolls 30, respectively.
At least one of the plurality of paper cassettes 22 is extendable and contractable, and includes a main frame 32 and an auxiliary frame 34 slidably provided with respect to the main frame 32. 1, when extended, the auxiliary frame 34 projects from the image forming apparatus main body 12 in the front direction by at least a length A, which is at least a part of the auxiliary frame 34, as shown by a dashed line in FIG. When contracted, the front wall of the main body 12 of the image forming apparatus is made to coincide with the front wall. This paper feed cassette 22 will be described later in detail.
The transport path 36 is a paper path from the nager roll 24 of the paper feed unit 18 at the lowermost end to the discharge port 38. The transport path 36 is located on the back surface of the image forming apparatus main body 12 (the left side surface in FIG. 1). ) Near the feed roller 30 of the sheet feeding unit 18 at the lowermost end and a transfer device 62 to be described later. A transfer device 62 and an image carrier 54, which will be described later, are arranged upstream of the fixing device 64 in the transport path 36, and a registration roll 40 is arranged upstream of the transfer device 62 and the image carrier 54. Further, a discharge roll 42 is disposed near the discharge port 38 of the transport path 36.
Accordingly, the sheet conveyed from the sheet feeding unit 18 is temporarily stopped by the registration roll 40 in the conveyance path 36 and sent to the image forming means 14 at a predetermined timing to form an image, and the discharge roll 42 Is discharged to the discharge unit 16.
However, in the case of double-sided printing, it is returned to the reversing path. That is, the front of the discharge roll 42 is divided into two forks, a switching claw 44 is provided at the divided portion, and a reversing path 46 returning from the divided portion to the registration roll 42 is formed. The reversing path 46 is provided with conveying rollers 48a to 48c. In the case of double-sided printing, the switching claw 44 is switched to the side where the reversing path 46 is opened, and the discharge roll 42 is moved toward the rear end of the sheet. The recording medium is guided to the reversing path 46, and is discharged to the discharge unit 16 through the registration roll 38, the transfer device 62, the image carrier 54, and the fixing device 64.
The discharge section 16 has an inclined section 50 that is rotatable with respect to the image forming apparatus main body 12. The inclined portion 50 has a lower outlet portion and is inclined so as to gradually increase toward the front (rightward in FIG. 1), with the outlet portion as the lower end and the raised tip as the upper end. The inclined portion 50 is supported by the image forming apparatus main body 12 so as to be rotatable about a lower end. As shown by a two-dot chain line in FIG. 1, when the inclined portion 50 is rotated upward and opened, an open portion 52 is formed, through which a process cartridge 68 described later can be attached and detached. .
The image forming means 14 is of, for example, an electrophotographic type, and includes an image carrier 54 made of a photoreceptor, a charging device 56 made of, for example, a charging roll for uniformly charging the image carrier 54, An optical writing device 58 for writing a latent image by light on the image carrier 54 charged by 56, a developing device 60 for visualizing the latent image of the image carrier 54 formed by the optical writing device 58 with a developer, A transfer device 62 formed of, for example, a transfer roll for transferring the developer image by the developing device 60 onto a sheet, a cleaning device 63 formed of, for example, a blade for cleaning the developer remaining on the image carrier 54, and a transfer device 62 for transferring the developer image. The fixing device 64 includes, for example, a pressure roll and a heating roll for fixing the developer image on the sheet to the sheet. The optical writing device 58 is composed of, for example, a scanning type laser exposure device, is disposed near the front of the image forming apparatus main body 12 in parallel with the above-mentioned sheet feeding unit 18, and exposes the image carrier 54 across the inside of the developing device 60. . The developing device 60 has a developing roll 66 facing the image carrier 54.
The process cartridge 68 integrates the image carrier 54, the charging device 56, the developing device 60, and the cleaning device 63. The process cartridge 68 is disposed immediately below the inclined portion 50 of the discharge portion 16, and is detached via the opening 52 formed when the inclined portion 50 is opened as described above.
FIG. 2 shows the paper feeding unit main body 20. The sheet feeding unit main body 20 is provided with a protruding portion 72 at an upper portion of the sheet feeding unit main body 70 on the sheet conveying side. The projecting portion 72 is provided with a conveying means 74. Further, a protective cover 76 is provided on the projecting portion 72 above the transporting means 74 so as to protect the pair of transporting means 74. Since the transporting means 74 is protected by the protective cover 76, it is possible to prevent the paper feeding unit 74 from being damaged when the paper feeding unit 18 is overlaid on the image forming apparatus main body 12, and to improve the safety of the operator. Can be secured. A guide portion 78 is formed inside the protective cover portion 76 so as to protrude in a rib shape so as to guide the sheet from the downstream to the conveying means 74. The protective cover 76 and the guide 78 are formed integrally with the paper feed unit main body 70.
The drive motor 80 is provided inside the side surface of the sheet supply unit main body 70. The drive motor 80 is connected to the above-described nudger roll 24, retard roll 26, and transport means 74 via a gear train 82, and drives these rolls based on a command from the image forming apparatus main body side. . As in this embodiment, since the drive system of the paper feed unit is provided in the unit main body and the drive transmission system is not divided, the drive transmission to each roll can be performed smoothly.
Reference numeral 84 denotes a connector for supplying electric power to the drive motor 80. A support plate 86 supports the nadger roll 24 and the feed roll 26, and is swingably supported by the paper supply unit main body 70.
FIG. 3 shows an example of the paper feed cassette 22. The main frame 32 supports the above-described retard roll 26 on the back side in the insertion direction of the sheet cassette 22. In the auxiliary frame 34 (see FIG. 1), the side surface of the auxiliary frame 34 is slidably inserted into the side surface of the main frame 32. The auxiliary frame 34 is provided with a front cover 88 at a front portion thereof, and the front cover 88 projects by a length A from the image forming apparatus main body. A sheet rear end guide 90 is erected in the auxiliary frame 34 so as to be movable in the front-rear direction. The rear end of the sheet stored in the set 22 is in contact with the sheet rear end guide 90. When storing a different sheet, the auxiliary frame 34 may be expanded and contracted from the main frame 32, and when the auxiliary frame 34 is extended, the sheet rear end guide 90 is moved and adjusted. Is also good.
The sheet stacking plate 92 is swingably provided at the bottom of the main frame 32. The sheet stacking plate 92 moves up and down in accordance with the remaining amount of sheets. The sheet stacking plate 92 has a control mechanism for always keeping the conveying position of the uppermost sheet stacked on the sheet stacking plate 92 constant. Is provided.
FIGS. 4, 5 and 6 show the arrangement of the nadger roll 24, the feed roll 28 and the retard roll 26. FIG.
The nager roll 24 and the feed roll 28 have a detachable transport roller portion 94, are supported by a first support portion 106 in a parallel cantilever state by a support plate 86, and are driven by a drive motor 80 via a gear train 82. Driven by a gear train 96. The feed roll 28 has a one-way clutch 98 between the transport roller 94 and the gear train 96, and rotates only in the direction in which the sheet is transported.
The retard roll 26 has a detachable transport roller 94, and the support 100 hung on the sheet cassette 18 by the hinges 102, 102 causes the first support 106 of the feed roll 28 to be shifted from the first support 106. It is supported in a cantilever state by the second support portion 108. Further, the retard roll 26 rotates in a direction in which the hinges 102, 102 are hooked on the sheet cassette 22, and the support 100 is pushed up from below by an elastic body such as a pressing spring 104.
The retard roll 26 provided opposite to the feed roll 28 has a torque limiter 104 that stops when a predetermined torque is exceeded between the transport roller 94 and the support 100, and is controlled by the nager roll 24. The conveyed sheet is paired with the convey roller portion 94 of the corresponding feed roll 28 to separate and convey the sheet.
As shown in FIG. 7, the height of the transport roller 94 of the feed roll 28 and the height of the transport roller 94 of the retard roll 26 are changed according to the distance from the support position.
Therefore, as shown in FIG. 5, the distance (a) from the first support portion 106 of the feed roll 28 to the transport roller portion 94 is increased by the distance from the second support portion 108 of the retard roll 26 to the transport roller portion 94. By making them approximately equal to (a), the amount of height displacement due to the distance from each support position in the pair of transport rollers 94 is offset, and the nip pressure of the transport rollers 94 against the sheet is made uniform.
Next, the operation of the above embodiment will be described.
The image carrier 54 is uniformly charged by the charging device 56, and the charged image carrier 54 is irradiated with light emitted from the optical writing device 58 based on the image signal to form a latent image. The latent image on the image carrier 54 formed by the optical writing device 58 is visualized by the developer of the developing device 60.
The sheet stored in one of the sheet feeding units 18 is sent out by a nudger roll 24, separated by a retard roll 26 and a feed roll 28, and reaches a conveying means 74. The sheet is temporarily stopped by the conveying means 74. It is guided between the transfer device 62 and the image carrier 54 at appropriate timing.
When the recording medium is guided between the transfer device 62 and the image carrier 54, the developer on the image carrier 54 is transferred to the recording medium by the transfer device 62. The sheet onto which the developer has been transferred is discharged to the discharge unit 16 through the fixing device 64.
As described above, the nudger roll 24, the feed roll 28, and the retard roll 26 of the paper supply unit 18 are supported in a cantilevered state, and are provided with a transport roller portion so as to be detachable. Is easy.
Since the feed roll 28 and the retard roll 26 are provided alternately at the supporting positions, the nip pressure can be made uniform even at the conveying roller portion far from the supporting position, and the sheet can be stably conveyed. Further, the nip pressures can be made substantially the same by making the distances of the paired conveying rollers from the supporting position substantially equal.
Even in the case where the distance from the support position to the transport roller unit cannot be adjusted due to inclusions or the like, stable torque can be obtained by providing the torque limiter 104 between the second support unit 108 and the transport roller unit 94 in the retard roll 26. Can be transported.
Further, the transport roller portion may not be removable.
In the above-described embodiment, the two paper feeding units 18 are provided in the image forming apparatus main body 12, but these paper feeding units 18 can be omitted. 18 is not limited to a two-stage paper supply unit, and may be one stage or three or more stages. Further, the present invention is not limited to the sheet feeding unit, but can be used for a general sheet conveying device.
[0034]
As described above, according to the present invention, since the rolls supported in a cantilevered state are alternately supported, the rolls can be set at a predetermined contact pressure, and the sheet can be accurately conveyed. be able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a paper feeding unit main body in the image forming apparatus according to the embodiment of the present invention.
FIG. 3 is a perspective view showing a sheet feeding cassette according to the embodiment of the present invention.
FIG. 4 is a perspective view showing an arrangement of a feed roll and a retard roll according to the embodiment of the present invention.
FIG. 5 is a front view showing an arrangement of a feed roll and a retard roll according to the embodiment of the present invention.
FIG. 6 is a side view showing an arrangement of a feed roll and a retard roll according to the embodiment of the present invention.
FIG. 7 is a diagram showing a displacement amount of a feed roll and a retard roll with respect to a support position in the embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 10 image forming apparatus 12 image forming apparatus main body 14 image forming means 18 paper feeding unit 20 paper feeding unit main body 22 paper feeding cassette 24 nadger roll 26 retard roll 28 feed roll 32 main frame 34 auxiliary frame 86 support plate 92 sheet stacking Plate 94 Conveyance roller section 96 Gear train 98 One-way clutch 100 Support body 102 Hinge 104 Torque limiter 106 First support section 108 Second support section

Claims (7)

It has a first transport roll supported in a cantilevered state, and a second transport roll supported in a cantilevered state, and the first transport roll and the second transport roll are supported alternately. And a sheet conveying device which comes into contact with a predetermined contact pressure. The first transport roll has a first spindle, and a first roller provided on the first spindle, the second transport roll has a second spindle, The seat according to claim 1, further comprising a second roller provided on the second support shaft, wherein the first roller and the second roller are in contact with each other. Transport device. The distance from the first support portion where the first support shaft is supported to the first roller portion, and the distance from the second support portion where the second support shaft is supported to the second roller portion 3. The sheet conveying apparatus according to claim 2, wherein the distances are substantially equal to each other. The said 1st roller part and the said 2nd roller part were detachably provided in the said 1st spindle and the said 2nd spindle, respectively, The Claim 2 or Claim 3 characterized by the above-mentioned. Sheet transport device. A paper supply unit main body, a paper supply cassette detachably inserted into the paper supply unit main body, a feed roll supported by the paper supply unit main body in a cantilever state, and supported by the paper supply cassette in a cantilever state A feed roll, wherein the feed roll and the retard roll are alternately supported and come into contact with a predetermined contact pressure. The paper feed unit according to claim 5, wherein the second transport roll further includes a torque limiter between the second support part and the second roller part. An image forming apparatus comprising the sheet supply unit according to claim 5.

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