JPH09319238A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily correct the dispersion of the stop angle of the driven shaft of a spring clutch continuously, to prevent the breakage of the spring clutch and to form a high-quality image by coupling an eccentric cam shaft with a driving shaft by engaging either joint with the other joint. SOLUTION: A supporting means drives and rotates a transfer belt corresponding to the transfer position of a photoreceptor and rocking supports it. An eccentric cam rocks the supporting means so as to make the transfer belt approach or separate corresponding to the transfer position of the photoreceptor. The eccentric cam shaft 5 rotatably supports the eccentric cam. The driving shaft 6 drives or stops the rotation of the cam shaft 5. Either joint 7 is set so that its rotation is free with respect to the shaft 6 and its movement in a shaft direction is restricted. The other joint 8 is set so that its rotation is restricted with respect to the shaft 6 and its movement in the shaft direction is free. A coupling means 9 couples the cam shaft 5 and the shaft 6 by engaging either joint 7 with the other joint 8.

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. More specifically, the present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a composite machine thereof that forms an image by moving a transfer belt to or from a transfer position of a photoconductor.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, for example, in an electrophotographic copying machine using an electrophotographic system, the image forming apparatus is moved toward or away from a transfer belt according to the transfer position of a rotatably supported photoconductor. Thus, the eccentric cam shaft of the eccentric cam, which maintains a predetermined transfer gap, transmits or stops the rotational driving force via a spring clutch. If the spring inside the spring clutch loosens from the driven shaft and the inner diameter of the spring and the outer diameter of the driven shaft vary when the driven shaft stops, the stop angle of the driven shaft varies.
It is known that one end of a spring can be re-engaged with another engaging hole of an engaging portion, or a follower shaft of a spring clutch can be provided with a biasing means to suppress the entrainment. (For example, JP-A-1-279121). However, depending on the transfer position of the photoconductor, the rotational driving force is transmitted via the spring clutch to the eccentric cam shaft of the eccentric cam that approaches or separates from the transfer belt to maintain a predetermined transfer gap. The image forming apparatus that stops has difficulty in stopping the driven shaft at a predetermined stop angle by approaching or separating from the transfer belt according to the transfer position of the photoconductor, and forcibly stops it by the urging means. If it is attempted to do so, the spring clutch may be damaged, and it becomes impossible to maintain a predetermined transfer gap between the photoconductor and the transfer belt, which makes it difficult to form a high-quality image.

[0003]

The above-described conventional image forming apparatus described above has an eccentric cam biasing device that approaches or separates from the transfer belt and maintains a predetermined transfer gap in accordance with the transfer position of the photoconductor. When the core cam shaft is rotationally driven or stopped via the spring clutch, it is difficult to stop the driven shaft of the spring clutch at a predetermined stop angle, or if the force is forced to stop it. Since the spring clutch was damaged, it was impossible to maintain a predetermined transfer gap between the photoconductor and the transfer belt, and it was impossible to form a high quality image.

Therefore, an object of the present invention is to solve such a problem. That is, when the eccentric cam shaft of the eccentric cam that approaches or separates from the transfer belt to maintain a predetermined transfer gap corresponding to the transfer position of the photoconductor is rotationally driven or stopped via the spring clutch. Another object of the present invention is to provide an image forming apparatus capable of easily correcting the variation of the stop angle of the driven shaft of the spring clutch without any damage and preventing the spring clutch from being damaged to form a high quality image.

[0005]

To achieve the above object, the present invention according to claim 1 is rotatable in an image forming apparatus for forming an image by moving a transfer belt toward or away from a transfer position of a photoconductor. And a transfer belt to which the toner image formed on the photosensitive member is transferred, and a support that rotatably drives the transfer belt corresponding to the transfer position of the photosensitive member to swingably support the transfer belt. Means, an eccentric cam that swings the support means to approach or separate the transfer belt in correspondence with the transfer position of the photoconductor, and an eccentric cam shaft that rotatably supports the eccentric cam. A drive shaft that rotationally drives or stops the eccentric cam shaft, one joint that is free to rotate with respect to the drive shaft and is constrained from axial movement, and a shaft that is constrained from rotation with respect to the drive shaft. The other joint that is free to move in any direction , In which a connecting means for connecting the eccentric cam shaft and the drive shaft is fitted with one of the joint and the other of the joint above.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the connecting means is such that a helical spline female and a helical spline male are fitted to each other.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the drive shaft has moving means for moving the position of the one joint or the other joint on the drive shaft. Be prepared.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the moving means includes a feed screw provided coaxially with the drive shaft.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, the drive shaft restrains the axial movement of the one joint or the other joint. It is equipped with means.

The image forming apparatus constructed as described above is
According to the first aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt corresponding to the transfer position of the photoconductor is rotationally driven with respect to the drive shaft that drives or stops the eccentric cam shaft. The eccentric cam shaft and the drive shaft can be connected by the connecting means by fitting the one joint that is constrained and the other joint that is restrained from rotating with respect to the drive shaft and free to move in the axial direction. .

According to a second aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt corresponding to the transfer position of the photoconductor is rotationally driven with respect to the drive shaft that rotates or stops in the axial direction. Of the joint where the movement of the eccentric cam shaft and the drive shaft is connected by fitting one joint whose rotation is restricted and the other joint whose rotation is restricted with respect to the drive shaft to allow free movement in the axial direction. The transfer belt can be moved toward or away from each other in accordance with the transfer position of the photoconductor by fitting and connecting the female and the helical spline male.

According to a third aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt in accordance with the transfer position of the photoconductor is rotationally driven or stopped with respect to the drive shaft that drives or stops the eccentric cam shaft. Of the joint of which the movement is restrained and the joint of which the rotation is restrained with respect to the drive shaft and the movement of which is free in the axial direction are fitted to couple the eccentric cam shaft and the drive shaft by the coupling means. At the same time, the position of one joint or the other joint on the drive shaft can be moved by the moving means.

According to a fourth aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt in accordance with the transfer position of the photoconductor is rotationally driven or stopped with respect to the drive shaft that drives or stops the eccentric cam shaft. Of the joint of which the movement is restrained and the joint of which the rotation is restrained with respect to the drive shaft and the movement of which is free in the axial direction are fitted to couple the eccentric cam shaft and the drive shaft by the coupling means. At the same time, the position of one joint or the other joint on the drive shaft can be moved by the feed screw by the moving means.

According to a fifth aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt corresponding to the transfer position of the photoconductor is rotationally driven or stopped with respect to the drive shaft that rotates or drives the eccentric cam shaft. Of the joint of which the movement is restrained and the joint of which the rotation is restrained with respect to the drive shaft and the movement of which is free in the axial direction are fitted to couple the eccentric cam shaft and the drive shaft by the coupling means. Both can restrain the moving position of one joint or the other on the drive shaft.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, an image forming apparatus of the present invention is, for example, a color copying machine using an electrophotographic system, in which a rotatably supported photoconductor 1 and a toner image formed on the photoconductor 1 are transferred. An image forming section 12 having a transfer belt 2 and the like, a color image reading section 14 for reading a color image of a document, a sheet feeding section 20 for placing and feeding a transfer sheet, and the like. It consists of

The color image reading section 14 forms an image on the color sensor 14d through an illumination lamp 14a for scanning a color image of an original driven by a stepping motor (not shown), a mirror group 14b and a lens 14c to form an image on the original. Color image information of blue (Blue), green (Gr
een) and red (Red) color-separated lights are read and converted into electrical signals.

The blue (Bl obtained by the color image reading unit 14
ue), green (Red), and red (Red) color-separated image signal intensity levels, and color conversion processing is performed by an image processing unit (not shown) to obtain black (Black), cyan (Cyan), and magenta ( Magenta) and yellow (Yellow) color image signals are obtained. This color image signal is converted into an optical signal, and optical writing corresponding to the original image is performed by the laser light, and the polygon mirror 15, f /
The charger 1 is operated through the θ lens 16 and the reflection mirror 17.
The surface 1a of the photoreceptor 1 uniformly charged by 8 is exposed to form an electrostatic latent image.

The electrostatic latent image formed on the surface 1a of the photoconductor 1 is transferred to the intermediate transfer belt 2 with the toner image developed and visualized in the developing device 19. This operation is performed in black (Black), cyan (Cyan),
Magenta, Yellow (Yello)
w) four times to form a four-color superposed toner image on the transfer belt 2 and transfer the paper onto the transfer paper (P) fed from the paper feed unit 20 and conveyed by the conveyance roller 21. Transferred by the roller 22. The transfer paper (P) onto which the toner image has been transferred is conveyed to the fixing device 24 by the conveying unit 23 to melt and fix the toner image, and then ejected from the ejection roller 25 to the ejection tray 26 for storage. It has become.

In FIG. 2, the transfer belt 2 is rotatably driven by the supporting means 3 and is swingably supported so as to approach or separate according to the transfer position of the photosensitive member 1. The supporting means 3 is composed of a supporting member 3b provided on the pulley 3a side facing the photoconductor 1, a supporting member 3d supporting the tension pulley 3c side, and an eccentric cam 4.

The support member 3b is a member that is swingably supported about the support shaft 3e and the support member 3d about the support shaft 3f. The support member 3b is rotated by a drive source (not shown) on the swing end side. It is a rocking lever in which rotation supporting portions of the driven pulley 3a and the tension pulley 3c are set. The surfaces of the support member 3b and the support member 3d that face each other are pressed against the eccentric cam 4 by a biasing member (not shown).

In the eccentric cam 4, the distance from the center of rotation of the eccentric cam shaft 5 to the facing surface of the support member 3b and the support member 3d, that is, when the cam lift makes a half rotation, the support member 3b and the support member 3d are the same. It is dimensioned so that it can move toward or away from the photoconductor 1 in the same direction, in other words, in the same direction, while maintaining the distance. In FIG. 3, a joint 5a is provided at one end of an eccentric cam shaft 5 rotatably supported by a bearing 27 fixed to the main body, and is engaged with one joint 7 on the main body drive side.

The one joint 7 is fitted with the other joint 8 arranged at one end of a drive shaft 6 coaxial with the eccentric cam shaft 5. On the other end side of the drive shaft 6, a half rotation step spring clutch 13 is fitted in a D-shape. The drive shaft 6 is rotated by the moving means 10 in the direction of the arrow A shown in the figure to indicate the position of the other joint 8 on the drive shaft 6 by the arrow B shown in the figure.
You can move in any direction. The spring clutch 13 is held by the bracket 13a.

In FIG. 4, the connecting means 9 is fitted with a helical spline female 9a provided on one joint 7 and a helical spline male 9b provided on the other joint 8.

In FIG. 5, the other joint 8 is free to rotate with respect to the drive shaft 6 when the drive shaft 6 is rotationally constrained by the D-shaped portion and moves in the axial direction indicated by the arrow C in the drawing. One joint 7 whose axial movement is restricted rotates in the direction of arrow D shown in the figure.

In FIG. 6, the feed screw 1 of the moving means 10
A pin 10b is attached to the tip of 0a so as to be rotatable in the direction of arrow E shown in the figure.

In FIG. 7, the moving means 10 has a feed screw 10a which meshes with a female screw 10b provided coaxially with the drive shaft 6. A groove 10c is provided in the D-shaped portion of the drive shaft 6, and the groove 10c guides the pin 10b. Therefore, by rotating the feed screw 10a in the direction of arrow F shown in the drawing, the pin 10b is moved in the axial direction of arrow G.

In FIG. 8, the other joint 8 and pin 10
b is connected, and the other joint 8 is moved in the axial direction by rotating the feed screw 10a. The movement of the other joint 8 causes the one joint 7 to rotate.

In FIG. 9, when the twisting direction of the helical spline female 9a and the helical spline male 9b of the connecting means 9 is such that a force acts in the direction of separating one joint 7 and the other joint 8 when the drive shaft 6 rotates. That is, when the rotation direction of one joint 7 and the twisting directions of the helical spline female 9a and the helical spline male 9b of the connecting means 9 are the same, the retaining ring 11a of the restraining means 11 causes the axial direction of the one joint 7 to move. It is designed to block and restrain the movement of.

In FIG. 10, in the case where the twisting direction of the helical spline female 9a and the helical spline male 9b of the connecting means 9 is such that a force acts in the direction of pulling in one joint 7 and the other joint 8 when the drive shaft 6 rotates. That is, when the rotation direction of one joint 7 and the twisting direction of the helical spline female 9a and the helical spline male 9b of the connecting means 9 are opposite to each other, the retaining ring 11b of the restraining means 11 causes the axial direction of the one joint 7. It is designed to block and restrain the movement of.

In FIG. 11, the spring clutch 13
The normal position of the flat part (D) of the D-shaped part of the drive shaft 6 of
As shown in the figure, it is in a state of facing upward.

In FIG. 12, however, the normal position of the flat part (D) of the D-shaped part of the drive shaft 6 is shown due to variations in various parts constituting the spring clutch 13 and wear of the spring and the like over time. In some cases, it may tilt from right above to the clockwise direction. In this case, the stop position of the eccentric cam shaft 5 connected by the joint 5a also deviates from a predetermined normal position, so that the stop angle of the eccentric cam 4 deviates (see FIG. 3), and The position where the supporting means 3 approaches or separates from the pulley 3a corresponding to the transfer position of 1 is misaligned (see FIG. 2).

In such a case, the feed screw 10a of the moving means 10 is rotated in the direction of the arrow H shown, and one joint 7 is rotated in the direction of the arrow H shown so that the stop position can be corrected. ing. One joint 7 is indicated by an arrow H
When the eccentric cam shaft 5 connected by the joint 5a returns to the predetermined normal position by rotating in the direction to correct the stop position, the stop angle of the eccentric cam 4 is corrected (see FIG. 3). (See FIG. 2), the pulley 3a of the supporting means 3 is located at a position approaching or separating corresponding to the normal transfer position of the photoconductor 1 (see FIG. 2).

[0033]

Since the present invention is configured as described above, according to the invention of claim 1, the eccentric cam biases the eccentric cam which approaches or separates the transfer belt corresponding to the transfer position of the photoconductor. One of the joints, which rotates or stops the core cam shaft, is free to rotate with respect to the drive shaft and whose axial movement is restricted, and the other, whose rotation is restricted with respect to the drive shaft and free to move axially. Since the eccentric cam shaft and the drive shaft are connected by the connecting means by fitting the joint, the transfer belt is moved toward or away from the transfer belt according to the transfer position of the photoconductor to maintain a predetermined transfer gap. When rotating or stopping the eccentric cam shaft of the eccentric cam via the spring clutch, it is possible to easily and steplessly correct the variation in the stop angle of the driven shaft of the spring clutch and prevent damage to the spring clutch. Then high quality images It has become possible to provide an image forming apparatus that forms.

According to the second aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt corresponding to the transfer position of the photoconductor can be freely rotated with respect to the drive shaft that drives or stops the eccentric cam shaft. The coupling means for connecting the eccentric cam shaft and the drive shaft by fitting one joint whose axial movement is constrained by the other joint and the other joint whose rotation is constrained relative to the drive shaft and whose axial movement is free Since the helical spline female and the helical spline male are fitted and connected to each other, the eccentricity keeps a predetermined transfer gap by approaching or separating from the transfer belt according to the transfer position of the photoconductor. When the eccentric cam shaft of the cam is rotationally driven or stopped via the spring clutch, the variation in the stop angle of the driven shaft of the spring clutch can be easily and continuously corrected by the helical spline and the spring clutch It damaged it is possible to form a high-quality image by preventing.

According to the third aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt corresponding to the transfer position of the photosensitive member can be freely rotated with respect to the drive shaft that drives or stops the eccentric cam shaft. The coupling means for connecting the eccentric cam shaft and the drive shaft by fitting one joint whose axial movement is constrained by the other joint and the other joint whose rotation is constrained relative to the drive shaft and whose axial movement is free And the position of one joint or the other joint on the drive shaft is moved by the moving means. Therefore, depending on the transfer position of the photosensitive member, the transfer belt is moved toward or away from the transfer belt and the predetermined position is set. When the eccentric cam shaft of the eccentric cam that maintains the transfer gap is rotationally driven or stopped via the spring clutch, the stop angle variation of the driven shaft of the spring clutch can be easily and continuously corrected by moving the position. With sp Corruption ring clutch it is possible to form a high-quality image by preventing.

According to the fourth aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt in accordance with the transfer position of the photosensitive member can be freely rotated with respect to the drive shaft that drives or stops the eccentric cam shaft. The coupling means for connecting the eccentric cam shaft and the drive shaft by fitting one joint whose axial movement is constrained by the other joint and the other joint whose rotation is constrained relative to the drive shaft and whose axial movement is free And the position of one joint or the other joint on the drive shaft is moved by the feed screw by the moving means. Therefore, it is moved toward or away from the transfer belt according to the transfer position of the photoconductor. Therefore, when the eccentric cam shaft of the eccentric cam that maintains a predetermined transfer gap is rotationally driven or stopped via the spring clutch, variations in the stop angle of the driven shaft of the spring clutch are eliminated by the position movement of the feed screw. Easy with steps Breakage of the spring clutch with a positive can it is possible to form a high-quality image by preventing.

According to the fifth aspect of the present invention, the eccentric cam shaft of the eccentric cam that approaches or separates the transfer belt corresponding to the transfer position of the photosensitive member can be freely rotated about the drive shaft that drives or stops the eccentric cam shaft. The coupling means for connecting the eccentric cam shaft and the drive shaft by fitting one joint whose axial movement is constrained by the other joint and the other joint whose rotation is constrained relative to the drive shaft and whose axial movement is free Since the moving position of one joint or the other joint on the drive shaft is restrained, the transfer belt is moved toward or away from the transfer belt in accordance with the transfer position of the photoconductor to set a predetermined transfer gap. When the eccentric cam shaft of the eccentric cam to be maintained is rotationally driven or stopped via the spring clutch, the stop angle variation of the driven shaft of the spring clutch can be easily and continuously corrected and the spring clutch can be prevented from being damaged or damaged. When rotating Occurrence of deviation also can form a high quality image by preventing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an outline of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a main part of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a state of another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is an exploded perspective view illustrating another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 5 is a perspective view illustrating a state of another main part of the image forming apparatus according to the exemplary embodiment of the present invention.

FIG. 6 is a perspective view illustrating a state of another main part of the image forming apparatus according to the exemplary embodiment of the present invention.

FIG. 7 is a perspective view illustrating a state of another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 11 is a perspective view illustrating a state of another main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 12 is a perspective view illustrating another state of another main part of the image forming apparatus according to the exemplary embodiment of the present invention.

[Explanation of symbols]

 1 Photoconductor 2 Transfer belt 3 Supporting means 3a Pulley 3b Supporting member 3c Tension pulley 3d Supporting member 3e Support shaft 3f Supporting shaft 4 Eccentric cam 5 Eccentric cam shaft 5a Joint 6 Drive shaft 7 One joint 8 The other joint 9 Connection Means 9a Helical spline female 9b Helical spline male 10 Moving means 10a Feed screw 10b Pin 10c Groove 11 Restraint means 11a Retaining ring 11b Retaining ring 12 Image forming section 13 Spring clutch 14 Color image reading section 14a Illumination lamp 14b Mirror group 14c Lens 14d Color Sensor 15 Polygon mirror 16 f / θ lens 17 Reflecting mirror 18 Charging device 19 Developing device 20 Paper feeding unit 21 Conveying roller 22 Paper transfer roller 23 Conveying unit 24 Fixing device 25 Discharging roller 26 Discharging tray 27 Bearing

Claims (5)

[Claims] 1. An image forming apparatus for forming an image by moving a transfer belt toward or away from a transfer position of a photoconductor, wherein a rotatably supported photoconductor and a toner image formed on the photoconductor are transferred. A transfer belt, a supporting unit that rotationally drives the transfer belt in correspondence with the transfer position of the photoconductor, and supports the transfer belt in a swingable manner; and a support unit that swings the support unit to correspond to the transfer position of the photoconductor. With respect to the transfer belt, an eccentric cam that rotatably supports the eccentric cam, a drive shaft that rotationally drives or stops the eccentric cam shaft, and And one joint whose rotation is free and axial movement is restricted, the other joint whose rotation is restricted with respect to the drive shaft and whose axial movement is free, and the one joint and the other Fitting the joint of the eccentric cam shaft An image forming apparatus comprising: and a connecting unit that connects the drive shaft. 2. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the connecting means is adapted to fit a helical spline female and a helical spline male. 3. The image forming apparatus according to claim 1, wherein the drive shaft includes a moving unit that moves a position of the one joint or the other joint on the drive shaft. Image forming apparatus. 4. The image forming apparatus according to claim 3,
The image forming apparatus, wherein the moving unit includes a feed screw provided coaxially with the drive shaft. 5. The image forming apparatus according to claim 1, 2, 3 or 4, wherein the drive shaft includes a restraint unit that restrains axial movement of the one joint or the other joint. A characteristic image forming apparatus.