JPH0688715B2 - Image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to post-separation conveying means for conveying a sheet material separated from an image carrier. Is.

[Prior Art and Problems] A conventional device diagram is shown in FIG. The relationship between the post-separation conveyance roller 13 and the conveyance belt 15 is provided with a conveyance guide 21 between them, and after the transfer, the separated sheet material P is conveyed and the leading edge is caught by the fixing rollers 20a, 20b. Sheet material P
Is located along the conveyance guide 21 and the conveyance belt 15, the shock of the rush into the fixing rollers 20a, 20b is transmitted to the rear end of the sheet material P as indicated by the arrow, and the sheet material P is affected at the transfer portion. However, there was a problem that transfer deviation occurred.

Further, since the cross-sectional shape of the conventional post-separation conveyance roller 13 is circular, when the length of the sheet material P is longer than between the fixing rollers 20a, 20b and the image carrier drum 12, it is pushed out to the image carrier drum 12. To the fixing rollers 20a, 20b,
When the length of the sheet after transfer is short or strong, when the leading edge of the sheet material hits the fixing entrance guide 19 or the fixing rollers 20a and 20b, the sheet material P slips on the conveying roller 13 after separation, and the fixing is performed. It had a drawback that it was not caught in the rollers 20a, 20b (Fig. 7). Further, for thick and small size paper such as business cards, cards and postcards, the rear end of the sheet material P is a roller after separation.
The tip of the sheet material P is fixed to the fixing roller while being mounted on the roller 13.
When trying to get caught between 20a and 20b, the fixing roller 20
There was a defect that the paper stopped because it did not penetrate well into the nip parts of a and 20b.

[Structure for Solving Problems] According to the structure of the present invention for achieving the above object, a sheet material separated from the image carrier is transferred to the fixing roller after the image on the image carrier is transferred in the transfer section. In an image forming apparatus that conveys a pair of sheets, it is provided in the vicinity of the separation position on the downstream side in the sheet material conveying direction, has a kicking portion on the peripheral surface, and moves endlessly to give a kicking force to the sheet material. The fixing roller is disposed between the kicking means and the kicking means and the fixing roller pair, and supports the sheet material fed by the kicking means at a position lower than the upper surface of the kicking means. An image forming apparatus, comprising: a conveying unit configured to convey a pair.

[Embodiment] FIG. 1 is a diagram of a post-separation conveying device according to the present invention, and FIG.
The figure is a sectional view of a transfer machine using the same. Sheet material P
Is imaged on the surface between the image carrier drum 12 and the transfer charger 11, the charge is removed by the charge elimination needle 24, and the image is separated from the image carrier drum 12. After that, the sheet material P is pushed at its rear end portion by the kicking roller 30, passes over the conveying belt 15 as the conveying means and the fixing entrance guide 19, and then passes through the fixing roller 20.
It is established in a and 20b.

In the post-separation conveyance device of this embodiment, a kick roller is used.
It is desirable that the top of 30 is higher by about 6 to 15 mm in the vertical direction than the top of the roller 23a that supports the conveyor belt 15. The cross-sectional shape of the kick roller 30 is as shown in FIG.
There is a kick-out protrusion 31 on the peripheral surface, and a kick-out portion 31a for pushing the rear end of the sheet material is provided at the front end in the rotational direction indicated by the arrow.

As shown in FIG. 5, the step H between the top of the kick roller 30 and the uppermost part of the roller 23a supporting the conveyor belt 15 is 6 to 15 m.
By setting m, as shown in FIG. 4, when the sheet material P plunges between the fixing rollers 20a and 20b, the shock is formed between the kicking roller 30 and the conveying belt 15. Is absorbed by the loop portion L of the sheet, and has an effect of preventing the transfer deviation or the like due to the rushing of the sheet material P into the fixing rollers 20a and 20b. Further, by providing the kick-out portion 31a on the peripheral surface of the kick-out roller 30, the rear end of the sheet material is pushed and the sheet material P such as thick small size paper hits the fixing entrance guide 19 and the fixing rollers 20a, 20b and stops. It is possible to prevent the accident. (FIG. 5) Further, the positional relationship between the kick roller 30 and the image carrier drum 12 is such that the center of curvature 12a of the image carrier drum 12 and the transfer charger 11
Kicking roller to a position far from the image carrier drum 12 side from a tangent line M contacting the image carrier drum 12 at a point T where the line connecting the charging wire 11a of the image carrier drum 12 intersects on the circumference of the image carrier drum 12 It is desirable to have 30 peaks.

[Advantages of the Invention] As described above, by adopting the configuration of the present invention, a reliable conveying force is applied to the separated sheet material, the sheet material slips on the conveying means, and the fixing roller located on the downstream side. The inconvenience of not being able to enter the pair can be eliminated.

Further, since the conveying means arranged between the kicking means and the fixing roller pair supports the sheet material fed by the kicking means at a position lower than the upper surface of the kicking means, the rear end is upward. Even if the curled sheet material curls back, the endlessly moving kicking portion pushes out the trailing edge to push it down, so a strong conveying force is applied to the sheet material, and the sheet material can surely enter the fixing roller pair. it can.

Furthermore, in the case of a long sheet in which the leading edge of the same sheet enters the fixing roller pair during transfer, a loop is formed between the kicking means and the conveying means, so that the sheet material rushes into the fixing roller pair. The shock at the time is absorbed by the loop, and transfer deviation can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a post-separation conveyance device using the present invention,
2 is a cross-sectional view of a kick roller, FIG. 3 is a cross-sectional view of a transfer machine using the present invention, FIG. 4 is an explanatory view showing a state where a sheet material forms a loop, and FIG. 5 is a thick sheet. FIGS. 6 and 7 are sectional views showing a conventional post-separation conveying device, which shows a state in which a material is extruded. 11 …… Transfer charger 12 …… Image carrier drum 15 …… Conveyor belt 20a, 20b …… Fixing roller 24 …… Discharge needle 30 …… Kicking roller 31 …… Kicking protrusion 31a …… Kicking part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeyoshi Onoda Inventor Shigeyoshi Onoda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-61-51454 (JP, A) Shoukai 57 -190551 (JP, U)

Claims (2)

[Claims] 1. An image forming apparatus that conveys a sheet material separated from the image bearing member to a fixing roller pair after an image on the image bearing member is transferred in a transfer section, wherein the sheet material is conveyed at the separating position. The kicking-out means, which is provided near the downstream side in the direction, has a kicking-out portion on the peripheral surface and moves endlessly to give a kicking-out force to the sheet material, and the kicking-out means and the fixing roller pair. And a conveyance unit that is disposed between the sheet ejection members and that conveys the sheet material fed by the kicking-out unit to a position lower than an upper surface of the kicking-out unit and conveys the sheet material to the fixing roller pair. Forming equipment. 2. The image forming apparatus according to claim 1, wherein the carrying unit has a carrying belt for carrying and carrying a sheet.