JPH08683Y2 - Color image forming device - Google Patents

Description

The present invention relates to an image forming apparatus having a transfer drum.

The fifth prior art color copying machine using the electrostatic photography process.
As shown in the figure, blue, green,
The light image of the original 3 which has been color-separated through the red color separation filters 2B, 2G, 2R and the neutral density filter 2N is exposed to form four types of latent images, and yellow, magenta, and
The cyan and black developing devices 4Y, 4M, 4C and 4BK are used for development, and the resulting four color toner images are fed onto the transfer drum 5 which is in contact with the photosensitive drum 1 and rotates at the same linear speed in synchronization. The transfer charger 7 superimposes and transfers the transfer paper on the transfer paper S which is fed from the section 6 to the position A and wound, and after the transfer is completed four times, the transfer paper is transferred by the separation claw 8 at the section B. There is well known a color copying machine of a so-called color separation image superposition transfer system in which the color copying machine is separated from the above and fixed by a fixing device 9 to obtain a color copy.

As the transfer drum, as shown in FIG. 6, the annular portions 10 at both ends of the drum and one connecting portion 11 for connecting them are provided.
And a frame body made of a metal such as aluminum made of aluminum and the like, both ends in the circumferential direction being held by the connecting portion 11, and both end portions along the outer peripheral surface of the annular portion 10, A structure having a dielectric flexible sheet 12 stuck in a cylindrical shape and a clamper 13 for gripping the leading end of a transfer sheet fed from a sheet feeder is widely used.

As the flexible sheet 12, a polyethylene terephthalate film having a thickness of about 75 to 150 μm is generally used. The front end and the rear end are fixed to the connecting portion 11 of the frame body, and both side portions are wound along the outer surface of the frame body. Is held.

The transfer paper fed from the paper supply unit and gripped by the clamper 13 of the transfer drum 5 is electrostatically adsorbed to the flexible sheet 12 within a range in which both ends do not overlap the annular portion 10 of the frame. The toner images of the four colors are superposed on each other without being displaced, and the toner images of the four colors are superposed on each other without being displaced.

By the way, the transfer drum 5 is rotated in contact with the transfer portion following the developing position of the photoconductor drum 1, and dust such as unfixed toner floats in the dirt on the photoconductor and in the air around it. Therefore, it is adsorbed on the surface of the dielectric flexible sheet 12 of the transfer drum 5, and the dirt increases with time. Flexible sheet
When the surface of 12 is soiled with toner, it adheres to the back surface of the transfer paper and becomes soiled. Especially in the case of a thin transfer paper, the color of the toner adhered from the surface can be seen through the paper, and the copy image on the surface becomes difficult to see.

 Further, if toner stains are stacked, the transfer efficiency will decrease.

Therefore, conventionally, a cleaning device for the surface of the flexible sheet of the transfer drum has been disclosed in, for example, Japanese Patent Application Laid-Open No. 58-63957 and Japanese Patent Publication No. 62-28468.

The former one is equipped with a cleaning member that comes into pressure contact with the surface of the flexible sheet, a backup member that faces the cleaning member via the flexible sheet, and a contacting / separating, locking, and releasing means for the cleaning member. The cleaning member does not include a position regulating means, and the pressure contact force of the backup member and the pressure contact force of the cleaning member directly oppose each other via the flexible sheet, thereby positioning the cleaning member, the flexible sheet, and the backup member. Since it is difficult to maintain the accurate position, when the flexible sheet is pushed inward from the outer peripheral surface of the annular portion at both ends of the transfer drum, the side edges of the flexible sheet are bent and plastically deformed for good cleaning. Can not be done, stain the back side of the transfer paper,
Also, as a result of the deformation of the flexible sheet, transfer omission occurs, resulting in uneven copying.

The latter one is composed of an elastic cleaning member that can be brought into contact with and separated from the outer peripheral surface of the transfer drum, but since it does not have a backup member or a position regulating means, it is difficult to position it as described above, and sufficient cleaning cannot be expected. Since the flexible sheet may be deformed, the same problem as in the former case is considered to occur.

SUMMARY OF THE INVENTION In consideration of the above problems of the conventional transfer drum cleaning device, the present invention achieves sufficient cleaning by bringing the cleaning member into pressure contact with the surface of the flexible sheet with a required pressure contact force. Moreover, it is an object of the present invention to provide an image forming apparatus having a cleaning device capable of preventing a problem caused by a flexible sheet being pressed from a circumferential surface of a predetermined transfer drum and deforming.

Means for Solving the Problems In order to solve the above problems, the present invention provides an image forming apparatus having the above-mentioned structure, wherein when the backup member is pressed against the inner surface of the flexible sheet by the backup contacting / separating member, the transfer is performed. It is characterized in that it has a regulating member which is in contact with the inner peripheral surface of the annular portion of the drum and determines the position of the backup member in the radial direction of the transfer drum with respect to the inner surface of the flexible sheet.

It is appropriate that the above-mentioned position regulating member regulates the position of the backup member to a position where the backup member travels slightly outward in the radial direction from the predetermined circumference of the flexible sheet.

The backup member is preferably made of a conductive material and grounded.

With the above configuration of the present invention, the backup member is restricted by the position restricting member to a position where the flexible sheet holds a predetermined cylindrical surface, and the cleaning member strongly presses the surface of the flexible sheet. Also, the flexible sheet is prevented from being deformed without being press-fitted from the outer peripheral surface of the annular portion of the frame body and extruded by the backup member.

Even if there are variations in the processing accuracy and the assembly accuracy of the members, the backup member can be flexibly moved to a position where it travels slightly outward in the radial direction from the predetermined surface of the flexible sheet. It is possible to prevent the sheet from being pushed inward from the outer peripheral surface of the frame and bending at both end portions.

When the backup member is made of a conductive material and is grounded, the cleaning effect can be improved by applying a bias potential having a polarity opposite to that of the developing toner to the cleaning member.

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

FIG. 1 is an enlarged sectional view of the transfer drum 5, and particularly shows the cleaning device of the present invention in detail.

The cleaning device is a transfer drum cleaning device having a cleaning member 21 in contact with the outer peripheral surface of the transfer drum 5.
20 and a backup roller device 30 having a backup roller 31 facing the cleaning member 21 via the flexible sheet 12.

FIG. 2 is a perspective view of the cleaning device, and FIG. 3 is a front view thereof.

Cleaning member 21 of the transfer drum cleaning device 20
A fur brush roller is used as the gear, and gears 21a and 21e are fixed to both ends of the shaft. The gear 21a meshes with a gear 25a fixed to the output shaft of the motor 25.
The gear 21e meshes with a gear 22a and a gear 21c provided at the shaft end of a toner collecting roller 22 provided in parallel with the fur brush roller 21 and biting into the fur brush roller 21. On the surface of the toner collecting roller 22, a blade 23 such as a wiper for wiping an automobile window glass is pressed. Fur brush roller
21, the toner collecting roller 22 and the blade 23 are cleaner frame bodies.
Housed within 24. The cleaner frame 24 is swingable about a support shaft 26, and is rotated by linking mechanisms 27, 28, 29 by means (not shown) to bring the cleaning member into contact with and separate from the flexible sheet 12. It is possible. When the motor 25 is rotated while the cleaning member (fur brush roller) 21 is in contact with the flexible sheet 12, the gear 25
The fur brush roller 21 rotates via a and 21e to clean the toner attached to the outer surface of the flexible sheet 12. Toner that adheres to the fur brush roller is removed by the gear 21e,
The toner is transferred to the rotating toner collecting roller 22 via 21c and 22a, is peeled off by the blade 23, and is collected in the frame 24.

Next, the backup roller device 30 will be described.
The backup roller 31 has one end supported by a fixed shaft 35.
It is pivotally supported on the other ends of the pair of levers 32 and 36, and can be brought into and out of contact with the flexible sheet 12 via a link mechanism by a solenoid 40. When the backup roller 31 is in contact with the flexible sheet, the lever 32 is urged to rotate in the clockwise direction around the support shaft 35 by a torsion spring or the like (not shown). Fur brush roller 21 to 12
It is pressed with a stronger force than the contact force of.

However, in the middle of the lever 32, a rigid body position control roller 34
Is pivotally supported by a shaft 33 that is planted in the lever.
Reference numeral 34 is in pressure contact with the inner peripheral surface of the annular portion 10 on both sides of the transfer drum frame to position the backup roller 31 in the radial direction of the transfer drum. The position is backup roller 31
The outer peripheral surface of the flexible sheet may be aligned with the inner peripheral surface (rear surface) of the flexible sheet at a predetermined position wound around the annular portion of the frame body. Even if the roller 21 is strongly pressed against the flexible sheet 12 for cleaning, the flexible sheet 12 is pressed and supported by the backup roller 31 from the back side with a force larger than that, so that the flexible sheet is pushed. Nonetheless, both end portions are not bent at the inner edge of the annular portion 10.
Further, since the backup roller 31 is restricted in its radial position by the restriction roller 34, the flexible sheet will not be pushed out.

It should be noted that the regulation position of the backup roller is set to a position where a business trip is made to the outside by a slight amount 1 from the position of the predetermined inner peripheral surface of the flexible sheet 12 shown by the two-dot chain line, as shown in FIG. This prevents the flexible sheet from being pushed inward from the predetermined position to bend the side end portion even if there are variations in the processing accuracy and assembly accuracy of the related members.

The backup roller 31, the levers 36 and 32, and the shaft 35 are electrically conductive members and are grounded by the electrically conductive contact piece 37 (FIG. 2), and the cleaning roller 21 and the toner collecting roller are also provided.
22 is made of a conductive material and bias voltage is applied from the bias power sources V ₁ and V _{2 having a} polarity opposite to that of the toner through the electric contact pieces 21f and 22b, and the voltage of V ₂ is made slightly higher than V _1. (FIG. 3), the toner and dust adhering to the cleaning roller 21 can be electrostatically attracted and collected, and the cleaning effect can be further improved.

As described above, according to the present invention, the cleaning member can be pressed against the flexible sheet of the transfer drum with sufficient pressing force to perform cleaning, and both ends of the flexible sheet are bent. Since it is not deformed, cleaning failure and transfer failure can be prevented. Moreover, by making the regulation position of the backup member slightly outside the predetermined position of the flexible sheet, it is possible to cope with variations in component accuracy and assembly accuracy, and the backup member is made of a conductive material. By grounding, the cleaning effect can be further improved by applying the bias.

[Brief description of drawings]

FIG. 1 is a sectional view mainly showing a cleaning device according to an embodiment of the present invention, FIG. 2 is a perspective view of the cleaning device, FIG. 3 is a front view thereof, and FIG. 4 is a vicinity of a backup roller of another embodiment. FIG. 5 is a side sectional view showing an overall schematic structure of a color copying machine to which the present invention is applied, and FIG. 6 is a perspective view showing the structure of the transfer drum. DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 5 ... Transfer drum 10 ... Annular part, 11 ... Connection part 12 ... Flexible sheet 20 ... Transfer drum cleaning device 21 ... Cleaning member (fur brush roller) 30 ... Backup roller device 31 ... Backup roller 32 ... Lever 34 ... Position regulating member

Claims (3)

[Scope of utility model registration request] 1. A frame body comprising annular parts at both ends of a drum and connecting parts for connecting these in an axial direction, both end parts in the circumferential direction are held by the connecting parts, and both end parts are outer circumferences of the annular part. A transfer drum formed in a hollow cylindrical shape by a dielectric flexible sheet wound around the frame along the surface is provided, and the transfer drum rotates in synchronization with the photosensitive drum in contact with the photosensitive drum. A toner image of different colors sequentially formed on the photoconductor is sequentially superposed and transferred onto a transfer paper that is electrostatically adsorbed and wound on a flexible sheet, and further, a flexible sheet of the transfer drum. Cleaning member for pressing the transfer paper supporting surface of the transfer paper to clean the supporting surface, a cleaning contacting and separating member for contacting and separating the cleaning member with the transfer paper supporting surface of the transfer drum, and a flexible member for the cleaning member. Hold the sheet and face it And a backup contacting / separating member for contacting / separating the backup member with respect to the inner surface of the transfer drum. In the color image forming apparatus, when the backup member is pressed against the inner surface of the flexible sheet by the backup contacting / separating member, the backup member comes into contact with the inner peripheral surface of the annular portion of the transfer drum, and the backup of the inner surface of the flexible sheet is performed. A color image forming apparatus comprising: a regulating member that determines a position of a member in a radial direction of a transfer drum. 2. A frame body comprising annular parts at both ends of the drum and connecting parts for connecting these in the axial direction, both end parts in the circumferential direction are held by the connecting parts, and both end parts are outer circumferences of the annular part. A transfer drum formed in a hollow cylindrical shape by a dielectric flexible sheet wound around the frame along the surface is provided, and the transfer drum rotates in synchronization with the photosensitive drum in contact with the photosensitive drum. A toner image of different colors sequentially formed on the photoconductor is sequentially superposed and transferred onto a transfer paper that is electrostatically adsorbed and wound on a flexible sheet, and further, a flexible sheet of the transfer drum. Cleaning member for pressing the transfer paper supporting surface of the transfer paper to clean the supporting surface, a cleaning contacting and separating member for contacting and separating the cleaning member with the transfer paper supporting surface of the transfer drum, and a flexible member for the cleaning member. Hold the sheet and face it And a backup contacting / separating member for contacting / separating the backup member with respect to the inner surface of the transfer drum. In the color image forming apparatus, the backup contacting / separating member presses the backup member against the inner surface of the flexible sheet, and the cleaning contacting / separating member presses the cleaning member against the transfer sheet supporting surface of the flexible sheet. At this time, a restricting member that restricts the backup member to a position in which the contact position of the backup member with the flexible sheet slightly protrudes outward in the radial direction of the transfer drum from the inner surface of the predetermined circumference of the flexible sheet. A color image forming apparatus characterized by having. 3. A frame body comprising annular parts at both ends of the drum and connecting parts for connecting these in the axial direction, both end parts in the circumferential direction are held by the connecting parts, and both end parts are outer circumferences of the annular part. A transfer drum formed in a hollow cylindrical shape by a dielectric flexible sheet wound around the frame along the surface is provided, and the transfer drum rotates in synchronization with the photosensitive drum in contact with the photosensitive drum. A toner image of different colors sequentially formed on the photoconductor is sequentially superposed and transferred onto a transfer paper that is electrostatically adsorbed and wound on a flexible sheet, and further, a flexible sheet of the transfer drum. Cleaning member for pressing the transfer paper supporting surface of the transfer paper to clean the supporting surface, a cleaning contacting and separating member for contacting and separating the cleaning member with the transfer paper supporting surface of the transfer drum, and a flexible member for the cleaning member. Hold the sheet and face it And a backup contacting / separating member for contacting / separating the backup member with respect to the inner surface of the transfer drum. In the color image forming apparatus, the backup member is made of a conductive material and is grounded.