JP2804319B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a color image forming apparatus and the like for transferring a toner image for each document color carried on a photosensitive drum onto a transfer paper wound around a transfer drum. The present invention relates to an image forming apparatus.

<Prior Art and Problems to be Solved by the Invention> Generally, in the above-described color image forming apparatus, a color separation image of a document is formed on a photosensitive drum, and a plurality of developing devices for each document color are , And the toner image of each document color is transferred to a transfer sheet.

Since it takes a certain time to select one of the plurality of developing devices and bring it closer to the photosensitive drum, the transfer drum is rotated once to adjust the timing to transfer the toner image of the next original color.

In this timing adjustment, if the transfer drum is rotated once while being in contact with the photosensitive drum, the toner transferred to the transfer drum immediately before returns to the photosensitive drum or the toner transferred to the transfer drum becomes It shifts.
To prevent this, each time a toner image of each original color is transferred,
The transfer drum is separated from the photoreceptor drum and idles, so that the above timing is adjusted.

FIG. 7 shows a conventional transfer drum supporting mechanism of an image forming apparatus. Referring to FIG. 7, one end 91a of a casing 91 supporting a transfer drum 90 is swingable about a shaft 92 as a fulcrum. The other end 91b of the casing 91
Are urged upward through the cams 94 and 95 by the urging force of the tension coil spring 93 as the urging means. Normally, the transfer drum 90 is brought into contact with the photosensitive drum 96 by the urging force of the tension coil spring 93 (the state shown by the solid line in FIG. 7). By casing 91
Is depressed so as to separate the transfer drum 90 from the photosensitive drum 96 (the state shown by a two-dot chain line in FIG. 7). When the casing 91 is removed from the image forming apparatus main body, a lever that can rotate integrally with the cam 94 is used.
By operating the 98, the engagement between the cam 94 and the cam 95 is released, and the transfer drum 90 is largely separated from the photosensitive drum 96.

In the above-described image forming apparatus, since the transfer drum 90 is urged toward the photosensitive drum 96 and is in contact with the photosensitive drum 96 in the normal state, the toner is applied to the peripheral surface of the photosensitive drum 96. There is a problem in that so-called filming that adheres in a thin film form occurs.

In order to solve such a problem, in a normal state, the transfer drum is urged or separated from the photosensitive drum by its own weight, and is elastically applied by the cam member only when necessary (during transfer). It is also considered that the transfer drum is brought into contact with the photosensitive drum by energizing.

However, for example, when the cam member stops in a state where the transfer drum is in contact with the photosensitive drum due to a power failure and the transfer drum is removed in this state, the photosensitive drum may be damaged.

The present invention has been made in view of the above-described problems, and provides an image forming apparatus that can prevent filming from occurring and can reliably prevent a photosensitive drum from being damaged when a transfer drum is removed. Aim.

<Means for Solving the Problems> In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus that transfers an image to a transfer paper wound around a transfer drum by a photosensitive drum. A casing that can be removed from the apparatus main body and a transfer drum that is rotatably supported, and the casing or the image forming apparatus main body has a contact position where the transfer drum contacts the photosensitive drum and a separation position where the transfer drum separates from the photosensitive drum. A state in which the transfer drum is moved to the contact position by pressing the support through an elastic member, the support being interposed between the support and the casing, the support being swingably supported between A cam member that is rotationally driven to allow the transfer drum to move to the separation position; and a cam member that is rotated after the transfer is completed to automatically displace the transfer drum to the separation position. A moving mechanism, a lever for manually operating the cam member through a one-way clutch, a gear, and a gear member intermittently meshing with the gear, and a lever provided on the image forming apparatus main body, displacing the transfer drum to a separation position. A stopper that engages with a lever that has been rotated in a direction opposite to the direction of rotation of the casing to regulate removal of the casing from the image forming apparatus main body. Wherein the gear member rotates integrally with the cam member and meshes with the gear in a state where the transfer drum is at the contact position.

<Operation> According to the image forming apparatus having the above configuration, the cam member moves the transfer drum to the contact position with the photosensitive drum only at the time of transfer, and moves to the separation position of the transfer drum after the transfer is completed. That is, since the contact of the transfer drum with the photosensitive drum is limited only when necessary, the contact time can be shortened, and the toner is formed in a thin film on the peripheral surface of the photosensitive drum. Adhered, so-called filming can be prevented from occurring.

In addition, the transfer drum and the photosensitive drum are always separated from each other at the time of removal, so that it is possible to prevent the transfer drum and the photosensitive drum from slidingly contacting each other and being damaged at the time of removal.

<Example> Hereinafter, an example will be described in detail with reference to the accompanying drawings.

FIG. 1 and FIG. 2 are schematic views showing a main part of a transfer drum of an image forming apparatus according to an embodiment of the present invention, respectively. Referring to FIG. 1 and FIG. The transfer drum 4 is brought into contact with the photosensitive drum 1 (see FIG. 1) by a shaft 3a removably supported by an image forming apparatus main body (not shown). A casing 2 which is swingably supported between a separating position (see FIG. 2) which separates from the body drum 1 and which is supported by the image forming apparatus main body by the accumulate 9 and which can be removed from the image forming apparatus main body 1 is provided. The pin 21 for supporting the support 3 at the time of the extraction is loosely fitted into the arc-shaped long groove 31 of the support 3.

The position G of the center of gravity of the support 3 to which the transfer drum 4 is attached
Is located to the right in FIG. 1 with respect to the vertical line l passing through the axis 3a serving as the swing center, the transfer drum 4 receives the urging force in the counterclockwise direction (moving direction to the separated position) due to its own weight. ing.

A compression coil spring 6 as an elastic member is attached to an end plate 32 of the support 3.
A cam follower 20 that presses the compression coil spring 6 has a shaft
It is mounted swingably around 20a.

The casing 2 is pressed against the support 3 via the cam follower 20 and the compression coil spring 6 to move the transfer drum 4 to the contact position (see FIG. 1) and to move the transfer drum 4 to the separated position. A cam member 5 allowing movement (see FIG. 2) is attached to the shaft 5a so as to be integrally rotatable.

Referring to FIG. 3, an engaging member 81 is attached to an end of the shaft 5a of the cam member 5 on the opposite side to the above-described cutting direction, and penetrates the side plate 82 of the image forming apparatus main body. Drive shaft 83
An axially movable member to be engaged 84 that engages with the engaging member 81 is attached to the end portion thereof while being pressed toward the engaging member 81 by a compression coil spring 85. . By the compression coil spring 85, the engaging member 81 and the engaged member
The shock at the time of engagement with 84 is reduced. The drive shaft 83 transmits the drive of a gear 87 connected to the drive system of the image forming apparatus via a spring clutch 88, and the cam member 5 is driven by the drive force. The cam member 5 is driven by the drive shaft 83 such that the state in which the transfer drum 4 is allowed to move to the separated position is the home position. That is,
After the transfer, the transfer drum 4 is always separated from the photosensitive drum 1.

4 to 6, a gear member 10 that rotates integrally with the shaft 5a is disposed at an end of the shaft 5a of the cam member 5 on the extraction direction side. Also, the casing 2 intermittently meshes with the gear portion 10a of the rotating gear member 10 only when the cam member 5 moves the transfer drum 4 to the contact position (see FIG. 1). A gear 11 rotating clockwise is supported by a shaft 13 (see FIG. 5).

A lever 7 for manually operating the cam member 5 is attached to the gear 11 via a one-way clutch 12. The one-way clutch 12 controls the rotation of the lever 7 only when the lever 7 is rotated clockwise from a vertical state (see FIG. 5) to an inclined state (see FIG. 6).
However, the rotation of the gear 11 rotating counterclockwise in the normal state is not transmitted to the lever 7.

Further, with respect to the image forming apparatus main body on the side of the casing 2 with which the lever 7 is removed, the removal of the casing 2 in a state where the transfer drum 4 is in the contact position (the vertical state of the lever 7)
Stopper 8 that regulates by engaging with lever 7
Are arranged. In a state where the movement of the transfer drum 4 to the separation position is allowed by the cam member 5 by tilting the lever 7, the stopper 8
And does not engage with it.

According to this embodiment, the transfer drum 4 is moved to the contact position with the photosensitive drum 1 only at the time of transfer by the cam member 5, and after the transfer is completed, the transfer drum 4 is moved to the separation position. Can be tolerated. That is, since the transfer drum 4 is brought into contact with the photosensitive drum 1 only when necessary, the contact time can be reduced, and the toner adheres to the peripheral surface of the photosensitive drum 1 in a thin film form. That is, filming can be prevented. Also,
When a selenium drum is used as the photoconductor drum 1, it is possible to prevent film roughness or the like due to deterioration of the surface of the photoconductor drum 1.

Further, when the casing 2 is to be removed while the cam member 5 is pressing the transfer drum 4 to the contact position,
The stopper 8 engages with the lever 7 for operating the cam member,
The stopper 8 regulates the removal, and the stopper 8 allows the removal in a state where the cam member 5 allows the transfer drum 4 to move to the separating position. Since the drum 1 is separated from the drum 1, it is possible to prevent the two from slidingly contacting each other at the time of extraction and being damaged. In the event of a power failure, if the transfer drum 4 is stopped in a state in which the transfer drum 4 is in contact with the photosensitive drum 1, there is no possibility of the above-mentioned damage even if the above-mentioned extraction is performed.

In the above embodiment, the support 3 is supported by the main body of the image forming apparatus. However, the support 3 may be supported by the casing 2.

In the above embodiment, the transfer drum 4 is urged in the separating direction by its own weight. However, the transfer drum 4 may be urged in the separating direction by an urging means such as a spring.

In addition, the present invention is not limited to the above embodiment, and various design changes can be made without departing from the spirit of the present invention.

<Effects of the Invention> As described above, according to the present invention, the cam member moves the transfer drum to the contact position with the photosensitive drum only during transfer, and separates the transfer drum after transfer is completed. Position is allowed, that is, the contact of the transfer drum with the photosensitive drum is limited when necessary, so that the contact time can be reduced, and the toner is deposited on the peripheral surface of the photosensitive drum by a thin film. It is possible to prevent so-called filming from adhering in a shape. Also, at the time of removal,
The transfer drum and photoconductor drum will be separated from each other,
This has a specific effect that it is possible to prevent the two members from sliding and being damaged at the time of removal.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part showing a state in which a transfer drum of an image forming apparatus as one embodiment of the present invention is in contact with a photosensitive drum, and FIG. 2 is a state in which the transfer drum is separated from the photosensitive drum. FIG. 3 is a cross-sectional view showing a drive connecting portion of a cam member, FIG. 4 is a cross-sectional view showing a connecting mechanism between a cam member and a lever, and FIGS. FIG. 7 is a schematic front view showing a regulation state and a removal allowable state, respectively. FIG. 7 is a schematic view showing a conventional transfer drum support mechanism. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum, 2 ... Casing, 3 ... Support body, 4 ... Transfer drum, 5 ... Cam member, 6 ... Compression coil spring (elastic member), 7 ... Lever, 8 ... Stopper .

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Kono 1-2-28 Tamazuki, Chuo-ku, Osaka-shi, Osaka Inside Mita Kogyo Co., Ltd. (72) Inventor Tsuyoshi Tsuda 1-2-1, Tamazuki, Chuo-ku, Osaka-shi, Osaka No. 28 Mita Kogyo Co., Ltd. (72) Inventor Naoki Mizutani 1-2-28 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Mita Kogyo Co., Ltd. (56) References JP-A-60-33575 (JP, A) JP-A JP-A-59-100475 (JP, A) JP-A-63-173076 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 13/01 G03G 15/01-15/01 117 G03G 13/14-13/16 G03G 15/14-15/16 103

Claims (1)

(57) [Claims] An image forming apparatus for transferring an image onto a transfer paper wound around a transfer drum by a photosensitive drum, a casing detachable from a main body of the image forming apparatus, a transfer drum supported rotatably, and A support that is swingably supported by a casing or an image forming apparatus main body between a contact position where the transfer drum contacts the photosensitive drum and a separation position where the transfer drum separates from the photosensitive drum; The transfer drum is rotated to a state in which the transfer drum is moved to the contact position by pressing the support via the elastic member, and a state in which the transfer drum is allowed to move to the separation position by the elastic member. A cam member, a driving mechanism for rotating the cam member after the transfer is completed, and automatically displacing the transfer drum to the separating position; a one-way clutch, a gear and a A lever manually operated through a gear member intermittently meshing with the gear in a sequential manner; and a lever provided on the image forming apparatus main body and rotated in a direction opposite to the rotation direction when the transfer drum is displaced to the separation position. A stopper that engages with a lever to regulate removal of the casing from the image forming apparatus main body; the one-way clutch allows only rotation of the lever corresponding to displacement of the transfer drum to a separation position; An image forming apparatus, wherein a member rotates integrally with the cam member and meshes with a gear when the transfer drum is at a contact position.