JPS5995562A - Paper conveying device - Google Patents

Abstract

PURPOSE:To prevent the disorder of a toner image due to the expansion of copying paper by providing a guide member and an air sucking means between two driving rollers between a transfer and a fixation part, and conveying the copying paper between the driving rollers in a curved state. CONSTITUTION:The copying paper P is conveyed to the transfer part T by a timing roller 13 and a toner image on a photosensitive drum 1 is transferred at the transfer part T; and the paper is guided by a guide plate 22 between the driving rollers 20 and 21 while forming a downward loop, and then looped in front of fixing rollers 5 and 5'. Then, when the rear end of the copying paper P leaves the transfer part T and is not applied with conveying force by the rotation of the photosensitive drum 1 any more, the force forming the loop is reduced, so the paper is to expand toward the transfer part T by its elasticity, but the amount of the loop between the driving rollers 20 and 21 increases to absorb the expansion. Consequently, the expansion of the transfer paper P never reaches the transfer paper T and the transferred toner image is not disordered.

Description

TECHNICAL FIELD The present invention relates to a paper conveyance device for a copying machine, and more particularly to a paper conveyance device between a transfer section and a fixing section.

Prior Art A conventional copying machine has a photosensitive drum (1
) The electrostatic latent image formed on the paper is developed with toner, and the toner image is transferred to the copy paper by the transfer charger (2), and then the copy paper is transferred to the conveyor belt by the suction force of the suction device (3).
(4,) It is configured to attract the toner image on two sides of the copy paper, and as the conveyance heald (4) moves, it is conveyed to the fixing roller (5) and (5) to fix the toner image on the copy paper.

Furthermore, the conveyance speed of the fixing section ([7), that is, the conveyance speed of the copy paper due to the rotation of the fixing roller, is the conveyance speed of the transfer section d'',
That is, if the conveyance speed of the copy paper is faster than the rotation speed of the photosensitive drum (1), the copy paper is forcibly pulled and conveyed, which disturbs the unfixed toner image on the copy paper. Therefore, it is necessary to match the conveyance speed of the fixing section (F) and the conveyance speed of the transfer section (r), but in reality, it is necessary to match the conveyance speed of the fixing section (F) and the conveyance speed of the transfer section (r). It is extremely difficult to always match the transport speeds of the fixing section and transfer section α- due to irregularities in component dimensions and diameter changes due to wear on the fixing roller (5) and (5) surfaces. The conveyance speed of the fixing section (g) is slightly higher than the conveyance speed of the fixing section (g). Therefore, the copy paper forms a loop in front of the fixing roller (5).

However, when trying to downsize a copying machine, it was not possible to keep the distance between the transfer section (I゛) and the fixing section (G) sufficiently large. ) is shorter than the copy paper being conveyed, the leading edge of the copy paper or the fixing roller (5) (even though it is held between
A situation occurs in which the trailing edge still exists in the transfer area.

If the fusing roller (5) is to form a loop of copy paper five positions in front of the fixing roller (5) in this state, the following inconvenience will occur.

In other words, if the surface of the conveyor belt (4) becomes gradually dirty with toner or paper powder, etc. and the coefficient of friction on the surface decreases, the conveying force of the conveyor belt (4) will become weaker, causing the paper in the loop portion to become dirty. Due to its stiffness, the first sheet of paper stretches toward the transfer section (1), causing disturbance of the transferred toner image.

Furthermore, when the trailing edge of the copy paper passes through the transfer section (r), it no longer receives the conveying force caused by the rotation of the photoreceptor drum (1).
Since the force that forms the loop becomes weaker, if the stiffness of the bale copying paper at the loop portion is greater than the conveying force of the conveyor belt (4), the strength of the copying paper or the transfer unit (■゛) as described above becomes weaker. As a result, the trailing edge of the copy paper again enters the transfer area (■゛), causing transfer misalignment at the trailing edge.

Purpose/Summary The present invention conveys copy paper from a transfer section that transfers the toner image on an image carrier to a copy set toward a fixing section that fixes the transferred toner image onto copy paper, and In a paper conveyance device that forms a loop in copy paper, the distance between the two drive rollers provided between the transfer section and the fixing section, and below the line connecting the upper edges of the drive rollers. It consists of a guide section provided and a means for suctioning air in the space formed between the drive rollers, and by conveying the copy paper in a curved state between the drive rollers, It is an object of the present invention to provide a paper conveyance device that can eliminate inconveniences.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 shows a schematic configuration of a copying machine to which the present invention is applied.

In the figure, a photoreceptor drum (1) is rotatably supported in a direction opposite to the pasting plate, and a charger (
6), optical system (7), developing device fit (8), transfer charger (2), separation charger (9), cleaning device (10), eraser lamp (11), etc. are arranged in order, and the photoconductor As the drum (1) rotates, the surface of the drum (1) is subjected to treatments such as electricity, fog light, and development, and is synchronized with the timing crawler (13) from the paper feed section (12). The toner image is transferred onto the copy paper being conveyed, and a fixing roller (5) fixes the toner image onto the copy paper to perform copying.

A paper conveyance device (A+) according to the present invention is provided between the photosensitive drum (1) and the fixing roller (5). Two drive rollers (20) that rotate synchronously and at a constant speed
, (21) and the drive rollers (20), (21), and below the line connecting the upper edges of each of the drive rollers (20), (21), and towards the drive roller (21). A kite board (22) and a drive roller (20) provided in close proximity
,<,21), and is provided below the drive roller (20),
(21) A suction device (3) that suctions the air in the space formed between the two.

The drive roller (20) moves in a tangential direction at a position corresponding to the transfer portion 1' on the surface of the photoreceptor drum (1).
0) It is provided near the separation charger (9) so that the upper edge thereof is located. Note that the upper edge of the drive roller (20) may be located about 2 to 3 nm below the tangential direction of the drive roller (20). In this way, the drive roller (2
0) If the edge of the copy paper is set in the tangential direction or slightly below the tangential direction, the leading edge of the copy paper will smoothly contact the surface of the drive roller (20) and receive the conveying force, thereby reducing impact. There is no way that this will adversely affect the transfer section.

On the other hand, the drive roller (21) is located approximately at the midpoint between the drive roller (20) and the fixing rollers (5), (5'),
The upper edge of the drive roller (21) is provided so as to be approximately at the same level as the line connecting the upper edge of the drive roller (20) and the fixing section (F). Then, two drive rollers (20
), (2) is formed of an elastic part made of, for example, rubber, and the coefficient of friction (w) of the roller surface 1 is increased in order to reliably convey the first sheet.

Next, the ``-'' side of the kite board (22) is provided with ribs so that the copy paper can slide smoothly on the top surface.

In addition, as described above, the guide plate (22) is connected to the drive port (22).
, 20), and (21) below the line connecting the upper edges of the sheets, or the lower part is a position that does not interfere with the formation of a copy paper loop, which will be described later. The kite board (22) may have a comb-shaped surface or may have a large number of holes.

The copy paper is conveyed by the paper conveyance device (A+) configured as described in 1 above, forming a downward loop between the drive rollers (20) and (21), will be explained and explained below using FIGS. 3(a) to fcl.

First, as shown in Figure 3(a), the timing crawler (13)
The gap between the copy sheets fed to the transfer section (l) at the same speed as the surface speed of the photoreceptor drum (1) is
1), a toner image is transferred by a transfer charger (2). Subsequently, it is separated from the photoreceptor drum (1) by the separation charger (9), and is driven by the movement of the drive roller (20) while being sucked downward by the suction force of the suction device (3), and the copy paper ( 1') Tip or kite board (22
) and reaches the drive roller (21).At this time, the copy paper (1'j is guided by the drive roller (21) with a loop formed downward between the drive rollers (20) and (21). Man(
22).

As shown in Fig. 3 (I), the leading edge of the copy paper t1') is located at the fixing roller (5) (even if there are five fixing sections (F), the trailing edge is a wooden transfer section). ing. And copy paper tp
+ indicates the fixing roller (5), which passes through the fixing section (1') at five surface speeds.
The surface speeds of ) and (5') are smaller than the conveyance speed at the transfer section), that is, the conveyance speed due to the rotation of the photoreceptor drum (1), and the conveyance speed of the drive rollers (20) and (21). Therefore, a loop is formed between the copy sheets before the fixing rollers (5) and (5').

Subsequently, as shown in FIG. 3(C), when the trailing edge of the copy paper (i') leaves the transfer section α') and is no longer subjected to the conveying force due to the rotation of the photosensitive drum (1), a loop is formed. Due to the stiffness of the paper, the loop in front of the fixing roller (5) tries to return to its original state and slips over the drive roller (2j) and ends up in the transfer section ( The conveying force of the drive roller (20) and the transfer part (
The force trying to extend to r) is multiplied, and S3 figure fc)
The loop amount between the drive rollers (20) and (21) increases as shown by the dotted line to absorb this elongation. Therefore, copy paper (1'
) does not reach the transfer portion, so the transferred toner image is not disturbed.

Note that the conveying speeds of the drive rollers (2 and (21) are respectively 1 and 2, the surface speed I of the drum (1) is VD, and the conveying speed of the timing roller (13) is V+<,
Fixing roller (5), (If the five surface speeds are VF,
It is desirable to have the relationship v2≧■I≧VR==Vp)Vp. However, the conveyance speed of the drive roller (21) ■
2 is faster than the conveyance speed of the drive roller (20), it is necessary to set the conveyance speed so that the copy paper forms a predetermined loop while passing between the drive rollers (20) and (21). There is.

In addition, even if the surfaces of the drive rollers (20) and (21) are gradually stained by toner, paper powder, etc., the friction coefficient of the surface decreases and the conveying force decreases, but the printing paper (not evenly distributed) Due to the rotation of the drive roller (20) in the conveying direction '\, a force acts in the direction of loop formation, and the force of elongation of the copy paper (uniform) as described above acts in the direction of loop formation.
The loop i+f between 20) and (21) also increases.

In this way, the elongation between the copy sheets is absorbed by increasing the number of loops 1. Therefore, the copy set H, (p
) or 11112 (there is no movement in the opposite direction), and no inconveniences such as uneven transfer or poor transfer occur.

Effects of the Invention As is clear from the explanation in Section 2, the present invention provides a transfer unit that transfers the toner image on the image (d) carrier onto the copy paper, and a fixing unit that fixes the transferred toner image on the copy paper. In a paper conveying device that rotates to convey a copy paper and forms a loop on the copy paper with a hand in a fixing section, two or more drive rollers are provided between the transfer section and the fixing section, and the drive roller The guide part is provided between the drive rollers and below the line connecting the upper edges of the drive rollers, and means for sucking air in the space formed between the drive rollers. Because the copy paper is transported in a bent state,
When the i1'11 distance between the transfer section and the fixing roller is set shorter than the copy paper being conveyed, and the copy paper forms a loop in front of the fixing roller, the stiffness of the paper in the loop part Even if the copy paper stretches toward the transfer section due to this, this stretch is absorbed by the larger loop formed between the two drive rollers, and this stretch does not reach the transfer section. Since JliL is small, a clear copy without any disturbance of the toner image can be obtained.

[Brief explanation of the drawing]

Fig. 2 is a schematic configuration diagram of a copying machine equipped with a conventional paper transport device, Fig. 2 is a schematic diagram of a copy machine equipped with a paper transport device of the present invention, Fig. 3 (a), +b ), +C+ is Nu1 indicating the state of conveyance of copy paper by the apparatus of the present invention. (1)...Photosensitive drum (2)...Transfer charger (3)...Suction device (5), (5'
)...Fixing roller (20), (srl)...Drive roller (22)...Kite plate 0゛)...Transfer section
(1.)...Fusing part (+))...Copy paper applicant Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. The copy paper is conveyed from the transfer section that transfers the toner image on the image carrier to the copy paper toward the fixing section that fixes the transferred toner image on the copy paper, and loops onto the copy paper before the constant N section. In the filter paper conveying device, between two drive rollers provided between the transfer section and the fixing section, and between the drive rollers,
Moreover, the kite member is provided below a line connecting the upper edges of the drive rollers, and means for sucking air in the space formed between the drive rollers, and the copying paper is bent between the drive rollers. A paper conveying device characterized in that it conveys paper in a suspended state.