JP2003292220A - Sheet carrying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet carrying device and an image forming device capable of easily assembling a separation claw holding unit without damaging the surface of a fixing roller as a carrying means. <P>SOLUTION: This sheet carrying device is provided with a carrying means for carrying a sheet, a contact member supported in a state capable of being oscillated and energized to the carrying means, a contact member holding unit for holding the contact member and for being attachable/detachable to/from the device main body, and a supporting shaft for holding the contact member holding unit and for making possible rotation of the contact member in the direction energizing the contact member to the carrying means. After the contact member holding unit is fitted to the supporting shaft, the contact member is energized to the carrying means by rotating the contact member holding unit around the supporting member and by positioning the unit. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine and a facsimile, and a sheet conveying apparatus provided for the image forming apparatus. In particular, a separating claw for separating a sheet from a roller for conveying the sheet and a separating claw. The present invention relates to the structure of the holding member.

[0002]

2. Description of the Related Art In an image forming apparatus, when a sheet is conveyed by using a conveying means such as a conveying roller or a conveying belt, the sheet may be wound around the conveying roller or the like. In such a configuration, a configuration in which a separation claw that is in contact with the transport roller or the like is provided in order to remove the sheet wound around the transport roller or the like is often used in known image forming apparatuses.

The structure of a conventional fixing device having a separating claw will be described with reference to FIG. Shown in the drawing is a fixing device 200 provided in the image forming apparatus, which has a fixing roller 201 and a pressure roller 202 that is in pressure contact with the fixing roller 201, and has a heater 203 inside each of them. . When the sheet on which the toner image is transferred by the image forming unit (not shown) is conveyed, the sheet is nipped and conveyed by the fixing roller 201 and the pressure roller 202 so that the toner image is melted and fixed on the sheet by being heated and pressed. It is conveyed along the guides 205 and 206 by the conveying roller pair 204. Here, since the sheet is wrapped around the fixing roller 201 by being heated and pressed, the separation claw 207 is provided to remove the sheet.

The separation claw 207 is rotatably supported by a metal separation claw holding member 208 by a rotation shaft 207a, and a tension spring 209 is provided.
The leading end 207b is urged by the fixing roller 201. With the above configuration, the sheet wound around the fixing roller 201 can be separated from the fixing roller 201 by the separating claw 207 as shown by the chain double-dashed line in FIG.

A conductive leaf spring 210 for grounding to the earth is attached to the separation claw holding member 208. The conductive leaf spring 210 is fixed to a top plate 211, which is a metal frame above the fixing device, with screws or the like, and is grounded via the top plate 211. By grounding in this way, the separation claw 207 is prevented from being charged, and the image forming apparatus is prevented from malfunctioning due to noise generated when the charged electricity is discharged.

As shown in FIG. 13, a plurality of separation claws 207 and tension springs 209 are attached to the separation claw holding member 208 to form a unit, and the separation claw holding unit R can be detachably attached to the apparatus main body. One end of the separation claw holding unit R is supported by shafts 213a and 213b fixed to the frame 212, and the other end is supported by a shaft 214a inserted through the frame 212. The shaft 214a is the hole 20 of the separation claw holding member 208.
When inserted in 8c and 208d, the shaft holding member 214 becomes the frame 2
Fixed at 12.

As shown in FIG. 14, a separation claw holding unit R
In the state where the separation claw 207 is not attached to the apparatus main body, the rotation of the separation claw 207 is restricted by the stopper 208a formed by bending a part of the separation claw holding member 208. Note that FIG.
As shown in FIG. 7, when the separation claw holding unit R is attached to the apparatus main body, the tip 207b of the separation claw 207 abuts the fixing roller 201, so that a gap is formed between the separation claw 207 and the stopper 208a. Is formed.

[0008]

However, in the above-described conventional configuration, when the separation claw holding unit R is attached, the fixing roller 201 may be damaged by the tip 207b of the separation claw 207.

More specifically, as shown in FIG. 14, since the separation claw 207 is positioned by the stopper 208a before the separation claw holding unit R is attached, the tip 207b is slightly protruded from the position after the attachment. Therefore, the normal position where the separation claw 207 contacts the fixing roller (see FIG. 14).
(The position of the chain double-dashed line in), when you try to install it by dropping it straight down,
Comes into contact with the fixing roller (C portion), and if it is forcibly lowered as it is, the tip 207b scratches and damages the surface of the fixing roller 201. Particularly, in order to improve the fixing property, the surface of the fixing roller 201 is softened to increase the nip with the pressure roller 202, so that the fixing roller 201 is easily scratched.

Since the fixing roller 201 is generally an expensive member, if it is damaged when it is attached and must be replaced, the production cost will be greatly increased. on the other hand,
If the assembling operator carefully assembles the product slowly so as not to scratch it, the assembly time becomes long, resulting in a device with high production cost.

Therefore, an object of the present invention is to provide a sheet conveying device and an image forming apparatus which can easily assemble the separation claw holding unit without damaging the surface of the fixing roller as the conveying means.

[0012]

In order to solve the above-mentioned problems, a typical structure of a sheet conveying apparatus and an image forming apparatus according to the present invention is a conveying means for conveying a sheet and a swingably supported member. In a sheet conveying apparatus having a contact member urged by a conveying means and a contact member holding unit which holds the contact member and is attachable to and detachable from the apparatus main body, the contact member holding unit is supported, and the contact member Has a support shaft that is rotatable in a direction biased by the conveying means, and after the contact member holding unit is attached to the support shaft, the contact member holding unit is rotated about the support shaft. The contact member is urged by the conveying means by positioning the contact member.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of a sheet conveying device and an image forming apparatus according to the present invention will be described with reference to the drawings.

(Overall Configuration of Image Forming Apparatus) First, the overall configuration of the image forming apparatus will be described with reference to FIG. The printer 100 is an image forming apparatus that employs an electrophotographic method. The sheets S stored in the feeding cassette 101 are separated and fed one by one by a feeding roller 102, and are conveyed to a registration roller pair 104 via a conveying roller pair 103 which is a conveying unit. The registration roller pair 104 corrects the skew of the sheet S and restarts the feeding at a predetermined timing.

Process cartridge as image forming means
The photosensitive drum 106, which is an electrophotographic photosensitive member 105, is uniformly charged by a charging unit (not shown), and then a latent image is formed by a laser beam from a laser scanner unit 108, which is an exposing unit. A toner image is formed on the photosensitive drum 106 by attaching toner to the latent image by the developing unit. The formed toner image is transferred to the sheet S by the transfer roller 107 that is a transfer unit.

The sheet S on which the toner image is transferred is conveyed to a fixing device T which is a fixing unit by the conveying force of the photosensitive drum 106 and the transfer roller 107. The sheet S is the fixing device T
The toner image is fixed by applying heat and pressure from the fixing roller 1 and the pressure roller 2 of the discharge roller pair 10
After 9 the sheets are loaded on the loading tray 110.

(Fixing Device) Next, referring to FIGS. 1 to 5,
The configuration of the fixing device as the sheet conveying device according to the present embodiment will be described. 1 is a main cross-sectional view illustrating a schematic configuration of a fixing device, FIG. 2 is a plan view illustrating a contact member holding unit, FIG. 3 is a front view illustrating the contact member holding unit, and FIG. 4 is a reciprocating unit of the contact member holding unit. FIG. 5 is a plan view illustrating the drive mechanism, and FIG. 5 is a view illustrating a state in which the reciprocating drive mechanism is removed.

As shown in FIG. 1, a fixing device T as a sheet conveying device has a fixing roller 1 as a conveying means and a pressure roller 2 in pressure contact with the fixing roller 1, and a heater 3 is provided inside each of them. have. When the sheet to which the toner image has been transferred is conveyed from the process cartridge 105, which is an image forming unit, the sheet is nipped and conveyed by the fixing roller 1 and the pressure roller 2 so that the sheet is heated and pressed to melt and fix the toner image on the sheet. Then, it is conveyed along the guides 9 and 10 by the conveying roller pair 8. Here, since the sheet is wound around the fixing roller 1 by being heated and pressed, a separating claw 4 as a contact member is provided to remove the sheet.

The separation claw 4 is pivotally supported by a metal separation claw holding member 18 by a rotary shaft 4a, and a hooking portion 18b of the separation claw holding member 18 and a tension spring 6 hung on one end of the separation claw 4 are used. The tip 4b of the separation claw 4 is biased by the fixing roller 1. The separation claw holding member 18 has a stopper 18a formed by bending a part of the separation claw holding member 18 to regulate the rotation range of the separation claw 4. With the above configuration, the sheet wound around the fixing roller 1 can be separated from the fixing roller 1 by the separating claw 4 and can be directed to the pair of conveying rollers 8.

A conductive leaf spring 7 for grounding to the earth is attached to the separating claw holding member 18.
The leaf spring 7 is a pressing means for pressing the separation claw holding unit V, and is fixed to a top plate 20 which is a metal frame above the fixing device by a screw or the like, and is grounded to the ground via the top plate 20. By grounding in this manner, the separation claw 4 is prevented from being charged, and the image forming apparatus is prevented from malfunctioning due to noise generated when the charged electricity is discharged. Further, since the leaf spring 7 is made of a conductive member, a new member is not required to ground the separation claw holding member 18 made of metal to the ground.

As shown in FIG. 2, a plurality of separation claws 4 and tension springs 6 (six in this embodiment) are attached to the separation claw holding member to unitize the separation claw holding member as a contact member holding unit. The unit V can be attached to and detached from the apparatus main body. One end of the separation claw holding unit V is supported by a support shaft 15a fixed to the frame 12 by caulking or the like, a prescribed shaft 15b, and the other end is supported by a support shaft 21a fixed by caulking or the like on the frame 12, a prescribed shaft 21b. It As a result, the separation claw holding member 18 can be rubbed in the direction orthogonal to the sheet conveying direction (axial direction of the fixing roller 1).

As shown in FIGS. 2 and 3, the separation claw holding member
A cam follower 19 is provided on the upper part of the top plate 20.
Is fitted to a cam 22 attached to the. Further, as shown in FIG. 4, the cam 22 is connected to the drive gear train 16 via the drive gear train 17 and the worm gear 16a, and the cam 22 is rotated by the drive transmitted from the fixing roller 1 in the arrow I direction. When the cam 22 is driven to rotate, the separation claw holding unit V is configured to reciprocate linearly in a direction orthogonal to the sheet conveying direction as indicated by an arrow H in FIG.

By thus performing the reciprocating linear movement (hereinafter referred to as reciprocation) of the separation claw 4 in the direction orthogonal to the sheet conveying direction, a structure in which the surface of the fixing roller 1 is not deeply scratched is widely used. This is because if the separation claw 4 is pressed against the fixing roller 1 with a certain pressure, the roller surface will be damaged. In particular, in a high-speed machine that has a large number of prints per unit time (hereinafter referred to as "throughput"), the surface of the fixing roller must be reduced in order to lower the hardness of the fixing roller surface and increase the nip with the pressure roller to improve the fixing property. Reciprocating is an essential technique because it is easily damaged.

The drive gear train 16, the drive gear train 17, and the cam 22 are attached to the top plate 20 above the fixing device. As shown in FIG. 5, it is possible to remove the top plate 20 as a unit. Has become. Since the gear train is arranged above the separation claw holding unit V in this manner, the assembly is easy and the device can be downsized.

(Detachable Structure of Contact Member Holding Unit) Next, the removable structure of the contact member holding unit, which is a feature of the present invention, will be described. FIG. 6 is a side view of the contact member holding unit, and FIG. 7 is a diagram illustrating an operation when the contact member holding unit is attached.

As shown in FIG. 6, a U-shaped rotation support hole 18c and a U-shaped positioning hole 18d are provided on the side surface of the separation claw holding unit V which is the contact member holding unit. The opening direction of the U-shape of the rotation support hole 18c is the direction in which the tip 4b of the substantially separating claw 4 is biased by the fixing roller 1. Further, the U-shaped opening direction of the positioning hole 18d (one-dot chain line F in the figure) is substantially perpendicular to the U-shaped opening direction of the rotation support hole 18c (one-dot chain line G in the figure), and downward (below). It is opened in the rotation direction of the separation claw holding unit V described later). Although not shown, a rotation support hole 18c and a positioning hole 18d are also provided on the object on the opposite side of the separation claw holding member 18.

A rotation support hole 18c provided on both sides of the separation claw holding member 18, a support shaft 15a in a positioning hole 18d, and a specified shaft.
By fitting the 15b, the support shaft 21a, and the regulation shaft 21b, the separation claw holding unit V can be rubbed in the direction orthogonal to the sheet conveying direction as described above with reference to FIG. Also, the positioning hole 18d is opened downward,
By pressing the leaf spring 7 from above (a direction substantially perpendicular to the opening direction of the rotation support hole 18c), the separation claw holding unit V is positioned and prevented from falling off.

Here, the support shafts 21a and 15a are fixed to the line E connecting the rotary shaft 4a which is the swing center of the separation claw 4 and the position where the tip 4b of the separation claw 4 contacts the fixing roller 1. It is arranged on the opposite side of the center of the roller 1.

The operation of mounting the separation claw holding unit V in the fixing device T having the above-described structure will be described with reference to FIG. As shown in FIG. 7A, before the separation claw holding unit V is attached, the separation claw 4 is biased by the tension spring 6 and its rotation is restricted by the stopper 18a of the separation claw holding member 18. And as shown in the figure, frame 12
The rotation support hole 18c of the separation claw holding unit V is slid into the support shaft 21a (the support shaft 15a on the opposite side) fixed to the above from diagonally above.

As shown in FIG. 7B, the tip 4b of the separation claw 4 comes into contact with the fixing roller 1 by advancing the separation claw holding unit V. Then, the separation claw holding unit V is further inserted, and the entire separation claw holding unit V is rotated downward (in the direction of arrow J) so that the positioning hole 18d is fitted to the specified shaft 21b (the specified shaft 15b on the opposite side). . Then, by attaching the top plate 20 to the fixing device T, the leaf spring 7
Presses the separation claw holding member 18, and the separation claw holding unit V is positioned.

Since the separation claw 4 is rotatable about the rotation shaft 4a, it can be rotated in the escape direction even if the above-described series of operations are performed after the tip 4b contacts the fixing roller 1. . Further, since the support shafts 21a and 15a are arranged on the side opposite to the fixing roller 1 with respect to the line E as described above, the tip 4b of the separating claw 4 easily escapes and the fixing roller 1 is not damaged. Therefore, the separation claw holding unit V can be attached quickly and smoothly without worrying about scratches on the fixing roller 1.

In this embodiment, the positioning hole 18d
The specified shafts 15b and 21b that are fitted to the separating claw holding units V are arranged on both sides of the separating claw holding unit V. This is because the separating claw holding unit V is not greatly deformed even if the fixing device T receives vibration or drop impact during transportation. belongs to. Therefore, if the rigidity of the separation claw holding unit V is maintained, there is no functional problem even if either of the specified shafts 15b and 21b is not provided. Also, the specified shaft 15b,
The same function can be achieved by providing a protrusion such as a rib protruding from the frame 12 instead of the 21b.

[Second Embodiment] A second embodiment of the sheet conveying apparatus and the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 8 is a side view of the contact member holding unit according to the present embodiment, FIG. 9 is a plan view illustrating the contact member holding unit, and FIG. 10 is a view illustrating an operation when the contact member holding unit is attached. The same parts as those in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted.

In the first embodiment, the rotation support hole
The support shafts 15a and 21a fitted to the 18c are fixedly provided on the frames 12 on both sides, but in the present embodiment, 1
A supporting shaft 25 penetrating the book is provided (see FIG. 9). Along with this, the separation claw holding member 23 according to the present embodiment has a U-shaped rotation support hole 23c in the upper portion (see FIG. 8).

As shown in FIG. 8, also in the separation claw holding member 23 of the separation claw holding unit Z according to the present embodiment, the stopper 23a, the hooking portion 23b of the tension spring 6 and the positioning, as in the first embodiment. It has a hole 23d. In addition, the U-shaped opening direction of the rotation support hole 23c is substantially the same as the tip 4 of the separation claw 4.
b is the direction in which the fixing roller 1 is biased, and the positioning hole
23d is opened in a direction substantially vertical to the rotation support hole 23c.

As shown in FIG. 9, the support shaft 25 is the frame 12
It is a shaft that penetrates between them. The separation claw holding unit Z according to the present embodiment is supported by the support shaft 25 and the defining shafts 15b and 21b so as to be slidable in the direction orthogonal to the sheet conveying direction.

When the Z having the above structure is attached to the fixing device T, first, similarly to the first embodiment, the support shaft 25 is used.
Then, the rotation support hole 23c of the separation claw holding unit Z is inserted obliquely from above. Then, as shown in FIG. 10, the tip 4b of the separation claw 4 contacts the fixing roller 1. Then, the separation claw holding unit Z is further entered, and the entire separation claw holding unit Z is rotated downward (in the direction of arrow J) so that the positioning hole 23d is fitted to the specified shafts 15b and 21b. By attaching the top plate 20 to the fixing device T, the leaf spring 7 presses the separation claw holding member 23, and the separation claw holding unit Z is positioned.

In the above operation, the separation claw 4 is rotated by the rotating shaft 4a.
Since it is rotatable about the tip, the tip 4b is fixed to the fixing roller 1.
Even after performing the above-described series of operations after the contact with, the fixing roller 1 can be rotated in the escape direction, and the fixing roller 1 is not damaged. Further, since the support shaft 25 is a single shaft, misalignment does not occur. Therefore, the two rotation support holes 23c at both ends are smoothly fitted to the support shaft 25, and even in the case of reciprocation, the support shaft 25 and the rotation support hole 23c can be smoothly operated without being bitten. Therefore, the separation claw holding unit Z can be attached quickly and smoothly without worrying about scratches on the fixing roller 1.

In each of the above-mentioned embodiments, the fixing roller is used as the conveying means, but the present invention is not limited to this, and in the case of separating sheets using separation claws, for example, a conveying belt or the like. Can be similarly applied to obtain the effects of the present invention.

[0040]

By the configuration as described above,
In the sheet conveying apparatus and the image forming apparatus according to the present embodiment, since the tip of the contact member does not scratch the surface of the conveying unit when the contact member holding unit is attached, the contact member does not scratch the surface of the conveying unit. The holding unit can be easily assembled.

As a result, it is possible to prevent the transporting means from being damaged at the time of assembling, so that it is possible to suppress an increase in production cost. Further, since it is not necessary for an operator to care, productivity is improved and assembly time is reduced. be able to. Further, when the conveying means is a fixing roller, a roller having a soft surface can be easily used in order to improve the fixing property.

[Brief description of drawings]

FIG. 1 is a main sectional view illustrating a schematic configuration of a fixing device.

FIG. 2 is a plan view illustrating a contact member holding unit.

FIG. 3 is a front view illustrating a contact member holding unit.

FIG. 4 is a plan view illustrating a reciprocating drive mechanism of the contact member holding unit.

FIG. 5 is a diagram illustrating a state in which a reciprocating drive mechanism is removed.

FIG. 6 is a side view of the contact member holding unit.

FIG. 7 is a diagram illustrating an operation when the contact member holding unit is attached.

FIG. 8 is a side view of a contact member holding unit according to a second embodiment.

FIG. 9 is a plan view illustrating a contact member holding unit according to a second embodiment.

FIG. 10 is a diagram illustrating an operation when the contact member holding unit according to the second embodiment is attached.

FIG. 11 is a schematic diagram illustrating an overall configuration of an image forming apparatus.

FIG. 12 is a diagram illustrating a configuration of a conventional fixing device having a separating claw.

FIG. 13 is a plan view illustrating a configuration of a contact member holding unit of a conventional fixing device.

FIG. 14 is a diagram for explaining an attaching / detaching operation of a conventional contact member holding unit.

[Explanation of symbols]

R: Separation claw holding unit S ... sheet T: Fixing device V: Separation claw holding unit Z ... Separation claw holding unit 1 ... Fixing roller 2 ... Pressure roller 3 ... Heater 4 ... Separation claw 4a ... Rotating shaft 4b ... tip 6 ... tension spring 7 ... Leaf spring 8: Transport roller pair 9… Guide 10… Guide 12… Frame 15a, 15b ... Support shaft 15b… Specified axis 16… Drive gear train 16a ... Worm gear 17… Drive gear train 18 ... Separation claw holding member 18a ... Stopper 18b ... Hook 18c… Rotation support hole 18d… Positioning hole 19… Cam followers 20… Top plate 21a, 21b ... Support shaft 21b… Specified axis 22 ... cam 23 ... Separation claw holding member 23a ... Stopper 23b ... Hook 23c… Rotation support hole 23d… Positioning hole 25… Support shaft 100… Printer 101… Feed cassette 102 ... Feeding roller 103… Conveyor roller pair 104… Registration roller pair 105… Process cartridge 106… Photosensitive drum 107… Transfer roller 108… Laser scanner unit 109… Ejection roller pair 110… Loading tray 200… Fixing device 201… Fixing roller 202… Pressure roller 203… Heater 204… Conveyor roller pair 205… Guide 206… Guide 207 ... Separation claw 207a ... Rotating shaft 207b ... Tip 208… Separation claw holding member 208a ... Stopper 208c ... hole 208d ... hole 209 ... tension spring 210… Conductive leaf spring 211… Top plate 212… Frame 213… Axis 214… Shaft holding member 214a ... Axis

Claims (12)

[Claims] 1. A conveying means for conveying a sheet, a contact member which is swingably supported and urged by the conveying means, and a contact member holding unit which holds the contact member and is attachable to and detachable from an apparatus main body. And a support shaft that supports the contact member holding unit and is rotatable in a direction in which the contact member is biased by the conveying unit, and supports the contact member holding unit. The sheet conveying device, wherein the contact member holding unit is urged by the conveying means by rotating the contact member holding unit about the support shaft and positioning the unit after the contact member holding unit is attached to the shaft. . 2. The sheet conveying apparatus according to claim 1, wherein the contact member holding unit can be attached to the support shaft by entering from substantially above the conveying unit. 3. The sheet conveying apparatus according to claim 1, wherein the conveying unit is a roller, and the contact member is a separation claw for peeling a sheet wound around the roller. . 4. The contact member holding unit has a U-shaped rotation support hole that fits into the support shaft, and the U-shaped opening direction of the rotation support hole is substantially equal to that of the contact member. The sheet conveying apparatus according to claim 1, wherein the sheet is conveyed in a direction biased by the conveying unit. 5. The sheet conveying device has a regulating shaft for positioning the contact member holding unit, the contact member holding unit has a U-shaped positioning hole, and the U-shaped rotation supporting hole has a U-shape. The opening direction of the shape and the opening direction of the U-shape of the positioning hole are substantially perpendicular to each other, and the contact member holding unit fits the rotation support hole to the support shaft, 5. The sheet conveying apparatus according to claim 4, wherein the sheet conveying apparatus is positioned by rotating the shaft about the center and fitting the positioning hole into the specified shaft. 6. The sheet conveying apparatus according to claim 3, wherein the roller is a fixing roller that fixes a toner image on a sheet. 7. The support shaft is on the opposite side of the center of the carrying means with respect to a line connecting the swing center of the contact member and the position where the contact member contacts the carrying means. The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. 8. The sheet conveying device according to claim 4, further comprising a pressing unit that presses the contact member holding unit from a direction substantially perpendicular to a U-shaped opening direction of the rotation support hole. 9. The sheet conveying apparatus according to claim 8, wherein the pressing means is a conductive spring. 10. The sheet conveying apparatus according to claim 1, further comprising driving means for driving the contact member holding unit, the reciprocating linear movement of the contact member holding unit in a direction perpendicular to the sheet conveying direction. . 11. The sheet conveying apparatus according to claim 10, wherein the driving unit is located above the holding member. 12. An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an exposing unit for exposing the charged electrophotographic photosensitive member, and the electrophotographic photosensitive member by the exposing unit. A developing unit for developing the electrostatic latent image formed above; a transferring unit for transferring the developed image to a recording material; and a fixing unit for fixing the transferred image on the recording material. , The fixing unit according to any one of claims 1 to 11.
An image forming apparatus comprising the sheet conveying device according to the above paragraph.