JPH0224129Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a transfer type copying machine, and more specifically,
The present invention relates to a braking device for a transfer drum in a transfer type copying machine in which a photosensitive drum and a transfer drum are disposed in opposing contact with each other.

(Prior Art) Conventionally, a type of transfer type copying machine has a photoconductor drum and a transfer drum that is disposed facing the photoconductor drum so that its peripheral surface is in contact with the photoconductor drum. There is a configuration in which a driven gear provided integrally with the transfer drum is meshed with the provided driving gear, and a driving force is applied to the driving gear to rotate both drums at the same circumferential speed.

In this type of copying machine, the transferred image contains so-called
Abnormal images such as image blur, image omission, and image blurring occur.

Additionally, color copying machines cause color misregistration.

The occurrence of these abnormal images is mainly caused by vibrations at the contact portions of both the transfer drum and the photoreceptor drum, and the cause of this vibration is found in the backlash of the meshing portion of the driving gear and driven gear.
It is generally difficult to remove the backup.

(Purpose) Therefore, the purpose of the present invention is to apply a braking force to the driven gear so that the tooth surfaces on the same side are always in contact with each other to transmit power, thereby preventing the vibration of the transfer drum caused by the above-mentioned bumpiness. The purpose of the present invention is to provide a drum braking device.

(Structure) The structure of the present invention will be described below based on one embodiment.

FIG. 1 shows the configuration of a color copying machine suitable for carrying out the present invention.

The details of the construction and operation of the color copying machine are explained in the specification and drawings of U.S. Pat.

In the figure, numeral 1 is the document placement glass, numeral 2 is
1 is an illumination lamp, 3, 4, 6, 7, and 8 are mirrors, 5 is an in-mirror lens, 9 is a filter, 10 is a photosensitive drum, 11 is a light-shielding plate, and 11A is a shaker of the light-shielding plate. 12 is a charger, 13 is an erase lamp, 14 is a yellow toner developing device, 15 is a magenta toner developing device, 16 is a cyan toner developing device, 17 is a transfer drum,
18 is a cleaning device, 19 is a static elimination charger, 20 is a paper feed cassette, S is a transfer paper, 21 is a feed roller, 23 is a registration roller, 24 is a stripping roller, 26 is a transfer charger 27A and 27B are separation chargers, 28 is a separation claw, 29 is a cleaning device, 31 is a fixing device,
Reference numeral 32 indicates a discharge roller.

In the filter 9, the red filters F, R, green filters F, G, and blue filters F, B are rotatable about the axis 9A, and each filter can be positioned on the exposure optical path as appropriate.

In FIG. 2, the shaft 105 of the photoreceptor drum 10
a is pivotally supported by a stationary member (not shown). A driving gear 105g is formed integrally with the photosensitive drum 10 at the right end of the photosensitive drum 10. This drive gear 105g is connected to a drive system (not shown).

Next, the transfer drum is made of a drum frame 106, which is formed by cutting out the central part of the cylindrical body leaving a band shape in the axial direction.
A sheet gripper 107 for gripping the transfer paper is provided on a band-shaped remaining thickness connecting the annular remaining thickness at both ends in the axial direction.
This sheet gripper 107 is pivotally supported on the drum frame 106a via a shaft 107a. One end of this shaft 107a is bent into an L-shape, and as the transfer drum 17 rotates, the L-shaped bent portion engages with a control cam (not shown) to open and close the sheet gripper 107. Further, a dielectric film 108 is wrapped around the drum frame 106a so as to sufficiently cover the notch.

Referring to FIG. 3, a female socket 106a ₁ is formed inside the right end of the drum frame 106a, and is fitted into the male socket of the rotating ring 110. Also, in this state, the drum frame 106a
The convex portion 106a ₂ fits into the concave portion 110a of the rotating ring 110. Thereby, the motion of the rotating ring 110 is reliably transmitted to the drum frame 106a.

A driven gear 11 is provided on the outer periphery of the right end of the rotating ring 110.
0g is formed and is meshed with the drive gear 105g. The pitch diameters of both gears and the outer diameters of the photosensitive drum 10 and the transfer drum 17 are all the same. Therefore, the drive gear 105g is the indicator P.
When the driven gear 110g rotates in the direction of arrow P', the peripheral speeds of both drums are equal. In the rotating ring 110, a projection 110b having a trapezoidal cross section is formed on the inner side corresponding to the driven gear 110g, and this projection 110b is fitted into a V-shaped groove of the guide roller 111. The V-shaped groove is formed by two mutually oppositely tapered thrust rollers 146 and 147 sandwiching a radial roller 145.
Furthermore, it is held by a spring plate ring 148, a spring receiver washer 149, a retaining ring 150, and the like. The guide rollers 111 are pivotally supported by a shaft 111a installed in the rocking plate 112, and at least two guide rollers 111 (total of three or more) in addition to those shown in FIG. 2 are similarly provided. . In other words, rotating ring 1
10 is rotatably supported on the swing plate 112 by at least three or more guide rollers. It is assumed that the guide rollers are arranged at equal intervals on the circumference inscribed in the protrusion 110b.

On the other hand, when paying attention to the left end of the drum frame 106a, a taper ring 115 is fixed there. The slope of the tapered portion formed inside the tapered ring 115 has a tendency that the inner diameter increases toward the outside (to the left). The tapered portions of at least three or more guide rollers 116 arranged at equal intervals on the circumference are in pressure contact with the tapered portion, so that the tapered ring 115
(Transfer drum 106) is rotatably supported.
The guide roller 116 is pivotally supported by a shaft 116a implanted in the swing plate 117. This allows the transfer drum 109 to move against the swing plate 117 as described above.
is rotatable. By the way, guide coro 1
The shafts on which the other two guide rollers other than 16 are supported are indicated by reference numerals 116b and 116c, respectively, in FIG.

The two swing plates 112 and 117 have a stay 118 that penetrates the inner space of the transfer drum 17 at the upper part thereof.
, and is further pivotally supported by a shaft 119 that commonly passes through the lower portions of each.

Note that the shaft 119 is fixed to a stationary member. The lower ends of each swing plate 112, 117 are pulled by compressible springs 120, 121, and a moment is generated in the direction of bringing the transfer drum 17 into contact with the photosensitive drum 10 and simultaneously meshing the driving gear 105g with the driven gear. has been added.

In this way, the transfer drum is rotatably supported between two mutually independent rocking plates 112 and 117, and furthermore, its circumferential surface is biased against the circumferential surface of the photoreceptor drum 10 in the longitudinal direction of the axis. A pair of springs 120 and 121 as shown in FIG.

As shown enlarged in FIGS. 4 and 5, the brake gear 122 according to the present invention is pivotally supported by a shaft 123 implanted in the swing plate 112 via a bearing 124. The braking gear 122 is integrally formed with a pulley 125, and a brake band 126 as a braking means is wrapped around this part, and one end of the brake band 126 is attached to a shaft 127 implanted in the rocking plate 112. The other end is connected to the shaft 1 via a tension spring 128.
It is attached to 29. This shaft 129 is the rocking plate 11
It is planted in 2.

Thus, a constant braking force is applied to the braking gear 122 by the spring 128. Therefore, drive gear 1
At the meshing part between 05g and driven gear 110g,
Since power is transmitted by always contacting the tooth surfaces on the same side, vibration of the transfer drum due to backlash does not occur.

Next, another embodiment will be described with reference to FIG.

In this example, a double-threaded bolt 129 is installed in the rocking plate 112, and a seat 129a of the bolt is installed.
A ring-shaped brake shoe 130 serving as a braking means is fitted into the bolt so as to be in contact with the bolt. Next, a brake gear 131 and a ring-shaped brake shoe 132 are fitted onto the bolt 129 in this order. Reference numeral 137 indicates a bearing. A ring-shaped pressing member 133 is provided on the outer surface of the brake shoe 132.
A keyway (not shown) is formed in this pressing member 133, and the bolt 129 is in contact with the pressing member 133.
It engages with a key 134 provided in the axial direction, and is prevented from rotating while only being allowed to move in the axial direction. This pressing member 133 receives a force in the direction of pressing the brake shoe 132 due to the spring force of an extensible spring 135 interposed between it and the nut 136, and thereby the braking gear 131 receives a constant braking force. , the same effect as in the above embodiment is achieved.

In FIG. 2, the sheet gripper 107 projects outward from the peripheral surface of the transfer drum 17. Therefore, in order to prevent the sheet gripper 107 from coming into contact with the circumferential surface of the photoreceptor drum 10 and damaging the photosensitive surface, the sheet gripper section includes a
Cam members 137, 138 (see FIG. 2) are provided. Then, when the sheet gripper portion approaches the photosensitive drum 10, the cam member 137,
138 separates the transfer drum 17 from the photoreceptor drum to prevent the sheet gripper from interfering with the photoreceptor. At this time, the swing plates 112 and 117 swing around the shaft 119, but as in each of the above embodiments, since the brake gear is provided on the swing plate 112, the brake gear 122 or 131 The positional relationship with the driven gear 110g is not affected, and a constant braking force can be continuously applied to the driven gear. Further, since the braking gear and the braking means are provided on the rocking plate, assembly and maintenance can be easily performed.

Incidentally, in a copying machine having a structure without the swing plates 112, 117 as in this example, the brake gear is of course set to an appropriate stationary member.

(Effects) Since the braking device according to the present invention prevents the vibration of the transfer drum caused by backlash, it is possible to prevent the occurrence of abnormal images in copies as described at the beginning.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a color copying machine suitable for carrying out the present invention, FIG. 2 is a perspective view of a transfer drum and a photosensitive drum, and FIG. 3 is a partial sectional view of the transfer drum.
FIG. 4 is a front view of the braking device according to the present invention, FIG. 5 is a side sectional view of the same figure, and FIG. 6 is a sectional view of the braking device illustrating another embodiment of the present invention. 10...Photosensitive drum, 17...Transfer drum,
110g...driven gear, 105g...driving gear,
122, 131... Brake gear, 126... Brake band, 130, 132... Brake shoe.

Claims (1)

[Claims for Utility Model Registration] In a transfer-type electrophotographic copying machine having a photoconductor drum and a transfer drum to which an image on the photoconductor drum is transferred, a pair of transfer drums rotatably support both ends of the transfer drum. a swinging plate; means for biasing the swinging plate in a direction that brings the transfer drum into pressure contact with the photoreceptor drum; a drive gear provided on the photoreceptor drum; and a drive gear provided on the transfer drum; A braking device for a transfer drum, comprising: a driven gear that meshes with the driven gear; a braking gear that is provided on one of the rocking plates and meshes with the driven gear; and a control means that applies a constant load to the braking gear.