JPS60138571A - Transfer belt device - Google Patents

Abstract

PURPOSE:To obtain a dichroic copy of high quality without color deviation while eliminating variation in path length between transfer positions of both photosensitive drums by holding the distance a transfer belt and a separation pawl constant even when the transfer belt has variance in peripheral length. CONSTITUTION:Pins 24 and 25 are implanted in a frame 17 and engaged with long-sized holes of a frame 18 to provide the frame in parallel to the common tangent connecting transfer parts of both photosensitive drums, and the frame 17 is allowed to move to and away from the frame 18 in parallel to the direction in which there should be the top surface of the belt. Further, a recessed part which allows a bearing 19 which support a shaft end of a driven roller 7 to slide only; in the common tangent direction is formed at the left end of the frame 17, and the bearing 19 is energized by a compression spring 15 in such a direction that tension is applied to the belt. Therefore, the tensile strength of the belt balances with the compressive force of the spring 15 and the bearing 19 shifts to right or left according to the difference in belt peripheral length, but the outer circumferential uppermost part of the driven roller is invariably on the common tangent.

Description

Detailed Description of the Invention Technical Field The present invention develops latent images formed on two photoreceptor drums with toners of different colors by light beams emitted from the same original document and split by a light beam splitting means. The obtained toner image is synchronously and overlappingly transferred to a transfer paper that is conveyed in contact with both photoreceptor drums V to make a two-color copy, and a toner image is formed only on the second photoreceptor drum, and the above-mentioned process is performed. This is directly related to the transfer belt device for conveying the transfer paper during the production of the two-color copy described above after copying, in which the single-color copy is produced by transferring the transfer paper to the transfer paper conveyed in contact only with the second photoreceptor drum along a different path.

An example of a transfer belt device for a two-color copying machine of the above type will be explained with reference to FIG. The first photoreceptor drum 1 and the second photoreceptor drum 2 are exposed at positions A and B, respectively, with images that are emitted from the same original and are divided into light beams, and different images are formed on the respective photoreceptors by an electrophotographic process. The color toner image is deposited on the transfer paper conveyed on the common tangent of the double-sided light body 1.2 at the contact point C1.
The image is transferred at position D under the action of the transfer charger 5.90, and after the transfer is completed, the transfer paper is separated from the second photosensitive drum 2 and then fixed by a fixing device (not shown) to produce a two-color copy. Ru. Normally, a toner image of a chromatic color such as red is formed on the first photoreceptor drum 1, and an achromatic toner image is formed on the second photoreceptor drum 2.
A black) toner image is formed. By making the difference between the creepage distance from A to C and the creepage distance from B to D equal to the distance from C to D, two-color toner images are transferred onto one transfer paper in a superimposed manner in alignment. However, in order to achieve transfer without color misregistration, the two photoreceptors 1 and 2 must be synchronized, and the paper must be moved at a specified speed without re-slip or sag on the conveyor belt. Good tracking is required. Always two photoconductors K
In a copying machine that transfers paper twice and performs two transfers,
The conveyor belt may be provided in contact with the transfer portion of the double-sided photoconductor, but as in the copying machine that is the object of the present invention, the conveyor belt 3 is in contact with the transfer portion of the second photoreceptor. 2 It is necessary to support and turn the photosensitive belt 2 with a driven roller 7 before the transfer section.The conveyor belt 3 is made of a dielectric material so that it can electrostatically attract the transfer paper and convey it without slipping or sagging. The belt 3 is formed as a belt (hereinafter referred to as the belt) and is wound around a driving roller 6 and a driven roller 7 made of conductive rubber under tension.
A charger 4 is provided on the outside of the drive roller 6 for charging, and a belt separation charger 29 is provided on the outside of the belt 3 in front of the driven roller 27, and a counter electrode is placed inside the belt 3, sandwiching the belt 3. A plate 14 is provided. At a position before being turned by the driven roller 7 and returning to the drive row 26, a static elimination charger 10 for the belt is placed inside, sandwiching the belt 3.
A counter electrode plate 13 is provided on the outside, followed by a cleaning blade 11, and a toner tray 12 below the cleaning blade 11.

In order to separate the transfer paper from the belt 3, a separation claw 8 is provided which is supported by a shaft 21 and whose right end in the figure is biased so as to come into pressure contact with the outer peripheral surface of the belt 3, which is wound around a driven roller π. . The upper edge of the separation claw 8 serves as a guide surface for guiding the separated transfer paper to the transfer portion of the second photoreceptor drum 2.

If the upper surface of the belt 3 and the upper edge of the separation claw 8 are arranged so as to coincide with the common tangent line CD between the first photoreceptor drum 1 and the second photoreceptor drum 2, the conveyance path can be maintained regardless of the type of paper. The length does not change and no transfer deviation occurs.

By the way, the transfer belt 3 has unavoidable variations in circumferential length due to production, and in order to absorb this variation and to constantly apply an appropriate tension, the driven roller 7 is supported on the frame via a spring. Ru.

Conventionally, the shaft 21 of the separating claw 8 is usually fixed to the frame of the main body of the copying machine. If the equivalence (() changes, the distance between the driven roller 27 and the separation claw shaft 21 changes, and the position where the tip of the separation claw 8 presses against the belt 3 on the driven roller changes. As a result, the separation claw 8 with respect to the belt 3 changes, and the direction in which the transfer paper enters the second photoreceptor drum deviates from the optimal direction.Furthermore, the guide surface of the upper edge of the separating claw is the conveying surface S of the belt 3. When the transfer paper is conveyed along the bent guide, the transfer paper is attracted to the belt while it is in contact with the belt 3, so the stiffness of the transfer paper, etc. The transport route will change depending on the
There was a drawback that the length of the transfer paper path from the transfer position C of the photoreceptor drum to the transfer position of the second photoreceptor drum 2 varied, causing color misregistration.

This invention eliminates the above-mentioned drawbacks of the conventional transfer belt device of the two-color copying machine of the above type, and always keeps the transfer paper in the second position even when the position of the driven roller changes due to variations in the circumference of the transfer belt. It is an object of the present invention to provide a transfer belt device that can enter the transfer position of a photoreceptor drum at an optimal angle and that does not cause color misregistration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail based on embodiments shown in the drawings.

FIG. 2 is a plan view of an embodiment in which the present invention is applied to the transfer belt device shown in FIG. 1, with the belt 3 omitted, and FIG. 3 is a side view thereof.

As can be seen from these figures, the frame that supports the driving roller 6 and the driven roller 7 around which the belt 3 is wound is large.
It is composed of a frame section 18 and a second frame section 17. The first frame portion 18 maintains a predetermined posture of the transfer belt device and receives belt driving force;
It is responsible for charging the belt, performing transfer from the first photoreceptor drum 1, neutralizing and cleaning the belt, and applying tension to the belt. The frame bodies 18 on both sides are integrally connected using the casings of the transfer charger 5 and the static elimination charger 10 as stays, and a conductive rubber drive roller 6 is attached to the bearing 2 at the right end.
It is pivotally supported via 7. The shaft ends on both sides of the drive roller 6 are further supported by bearings 26, and one of the bearings 26.
A drive gear 28 is provided between 270 and 270 .

The second frame part 17 is responsible for neutralizing the transfer paper, regulating the moving direction of the driven roller, and supporting the separation claw shaft, and the frame main bodies 17 on both sides are integrated with the counter electrode plate 14 of the belt separation charger as a step member. are connected to each other. The second frame 17 has two pins 24.2 on each side as shown in FIG.
5 are implanted, and these fit into long holes 18a and 18b formed in the first frame 18. Long hole 18a
.

181), the axis Q, i) of the first and second photosensitive drums 1.
They are provided in parallel to the straight line connecting the transfer parts C and D of 2 (common tangent line of both photo drums 1.2), and their right ends are enlarged so that the enlarged heads of pins 24 and 25 can pass through them. In order to facilitate the work of attaching and detaching the belt, a recess is provided in the middle part so that the driven roller 7 can be moved in a direction toward the driving roller 6 against the spring 15, and the pins 24 and 25 can be used to hold the driven roller 7. This is provided. Therefore the second frame 1
7 is taken by moving parallel to the straight line CD K with respect to the first frame 18, that is, parallel to the direction in which the upper surface of the belt 3 should be.

At the left end of the second frame 17, as shown in FIGS. 3 and 6, a bearing 19 that pivotally supports the shaft end of the driven roller 7 is mounted in a straight line CD.
A U-shaped recess 17a that is slidable only in the direction shown in FIG. The belt 3 is biased in a direction to apply tension to the belt 3 by a compression spring 15 stretched therebetween. As a result, the tensile force of the belt 3 and the compressive force of the spring 15 are balanced, and although the position of the bearing 19 in the left-right direction in the figure fluctuates due to the difference in belt circumference, the top of the outer circumference of the driven roller 7 is always on the straight line CD. exists in The bearing 19 and the pin 24 are held at 5 by a holder wire 16 so as not to separate from each other.
The frame 17 is displaced following the driven roller 7. As shown in FIG. 4, side holders 20 are fitted to the outer ends of the bearings 19 on both sides so that they cannot rotate or slide in the front-rear direction.
A shaft 21 of the separation claw 8 is supported non-rotatably at the left end of the side holder 20. The shaft 21 is shown in Fig. 5 (a) (b).
) As shown in FIG. 5(c), a plurality of separation claws 8 are rotatably supported and urged to rotate clockwise in FIG. 5(c) by a torsion spring 22. Milling part 2 of shaft 21
1a and a protrusion 8a provided on the side surface of the separation claw 8 engage with each other, thereby positioning the separation claw 8 in the axial direction and preventing excessive rotation. This is the side holder 20 when replacing the belt.
Since it is separated from the belt device section at the part, the purpose is to align the separating claws to some extent to make setting easier. The distal end 8c of the separating claw 8, which is biased clockwise, comes into contact with the circumferential surface of the belt on the driven roller 7, and its posture is determined. In this way, the upper edge of the belt's upper surface S1 separating claw 8 is placed on the straight line CD as a whole. Even if the driven roller 7 is displaced from side to side due to variations in the circumferential length of the belt, the positional relationship between the driven roller 7 and the separation claw 8 is regulated by the side holder 20, so the separation claw 8 moves in the direction of the straight line CD. Just move together with 7, the posture will not change,
The direction in which the transfer paper enters the second photoreceptor drum 2 does not change, and the upper surface S of the transfer belt 3 and the upper edge of the separation claw 8 are always held in a straight line, so that different types of transfer paper are transported. Even if this happens, there is no change in the transfer paper path length between the transfer portions C1D of the first and second photoreceptors, and it is possible to prevent the transfer position from shifting.

Effects As described above, according to the present invention, even if there are variations in the circumference of the transfer belt, the distance between the transfer belt and the separation claw is maintained constant π, and the transfer paper is always kept in the same posture and transferred to the second transfer sheet at an optimal angle.
It can enter the transfer section of the photoreceptor drum, and since there is no change in the path length between the first and second photoreceptor drum transfer positions, it is possible to obtain high-quality two-color copies without color shift. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an example of a photoreceptor and transfer belt device of a two-color copying machine to which the present invention is applied, and FIG. 2 is a plan view showing an apparatus according to an embodiment of the present invention with the belt omitted. , Fig. 3 is a side view of the side holder, Fig. 4 is a side view of the side holder, and Fig. 5 (
a), (b), and (c) are a top view, a top view and a side view of the spring mounting portion, respectively, and FIG. 6 is a side view of the second frame. 1... First photosensitive drum 2... Second photosensitive drum 3... Dielectric belt (transfer belt) 6... Drive roller 7... Followed roller 8... Separation claw 17...・Second frame member 18...First frame member 19...Followed roller shaft 20...Side holder (support member) 21...Separation claw shaft

Claims (1)

[Claims] (1) A toner image obtained by developing latent images formed on the first and second photoreceptor drums with toners of different colors using light beams emitted from the same original and split by a beam splitting means. are synchronously and overlappingly transferred onto transfer paper that is conveyed sequentially to both photoreceptor drums to create a two-color copy.
The above-mentioned two-color copy production method for a copying machine that forms a toner image only on the second photoreceptor drum and transfers it to a transfer paper that is conveyed in contact only with the second photoreceptor drum through a different path to create a single-color copy. A transfer belt device for conveying transfer paper at the time, the first
an endless dielectric outer belt wound around a driving roller and a driven roller in order to transfer the toner image from the photoreceptor drum and to hold the transfer paper in close contact and convey it toward the second photoreceptor drum; In the transfer belt device described above, the transfer belt device has a separation claw that separates the transfer paper from the dielectric belt at the turning position of the driven roller and guides the separated transfer paper to the transfer portion of the second photoreceptor drum at the upper edge. The driven roller is supported by a frame that supports the driving roller and the driven roller via a spring that urges the driving roller away from the driving roller, and a bearing that supports the driven roller is made non-rotatable and fixed to a predetermined position. The frame is provided with a guide means that is movable only in a direction parallel to the transfer paper conveyance direction, and the separating claw is driven by a shaft attached to a support member that is non-rotatably engaged with the driven roller bearing. The tip facing the roller is biased and attached so as to come into pressure contact with the outer circumferential surface of the driven roller, and with the tip in contact with the outer circumferential surface of the dielectric belt wound around the driven roller, the upper edge of the separating claw is in line with the transfer paper conveying surface of the dielectric belt. :2) A first frame member in which the frame pivotally supports the drive roller and supports the driven roller via the spring, and means for non-rotatably guiding the bearing of the driven roller in the predetermined direction. A guide means is provided on both of the frame members to enable the second frame member to move parallel to the first frame member in the predetermined transfer paper conveyance direction. A transfer belt device according to claim 1, characterized in that: