JPH0441352A - image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an image forming apparatus such as an electronic copying machine, and more particularly to an apparatus for conveying a sheet material to an image forming section of an image forming apparatus.

(B) Prior Art Conventionally, in an image forming apparatus such as an electronic copying machine, a toner image formed on a photosensitive drum is transferred to a sheet material and then fixed at a fixing position to form an image. The above-mentioned image forming apparatus has a registration roller that conveys the sheet material to the photosensitive drum while adjusting the relative timing between the toner image on the photosensitive drum and the sheet material to which it is transferred. Image forming apparatuses have been developed that include a mechanism that prevents lateral displacement of the sheet material by allowing registration rollers to move in a direction perpendicular to the conveying direction of the sheet material.

FIG. 3 shows the vicinity of the registration rollers of a copying machine to which the present invention is directed. In the figure, a photosensitive drum 1 has a toner image formed on its circumferential surface by a well-known electrophotographic method, and is rotating in the direction of the arrow. Near the photosensitive drum 1, there is an upper roller 5a and a lower roller 5 that is in pressure contact with the upper roller 5a.
A pair of registration rollers 5 consisting of b are provided. A slip roller 2 is disposed near the upstream side of the pair of registration rollers 5, and is pressed against the pair of registration rollers 5 with a relatively small force. A guide plate pair 3 is provided.

FIG. 4 shows an example of an alignment mechanism for aligning the pair of registration rollers 5 against lateral displacement.

In the same figure, a shaft 10 to which an upper roller 5a of a pair of registration rollers 5 is fixed and a shaft 11 to which a lower roller 5b is fixed are connected to a pair of side plates 15 and 1 through bearings 12 and 13.
6 are installed respectively. Gears 20, 21 that mesh with each other are fixed to each shaft 10, 11, and connecting members 17 are loosely engaged with the ends of each shaft 10, 11, and can be pulled out by snap rings 19. has been stopped.

Both arms 22, 22b of a channel-shaped holding member 22 are pivotally attached to the end of the shaft 10, and the snap ring 2
3 prevents the holding member 22 from being removed, and the holding member 22 is guided movably in the axial direction of the shaft 10 by a guide member (not shown). A pinion 26 fixed to a shaft 25 is attached to a rack 22c formed at the lower part of the holding member 22.
are in mesh with each other, and the pinion 26 is rotated forward and backward in the directions of arrows 27a and 27b by a pulse motor connected to the shaft 25 to move the pair of registration rollers 5 and the sheet material S held in the nip thereof in the axial direction. (in the lateral displacement direction of the sheet material S). Furthermore, when the sheet material S moves to a predetermined position in the lateral direction, the edge of the paper on the side blocks light from a photo sensor (not shown), and the rotation of the binion 26 is thereby stopped under the control of a controller (not shown). There is.

Between the arms 22a and 22b of the holding member 22 is an electromagnetic clutch 30 consisting of a clutch 30b fixed to the shaft 10 and a gear 30a rotatably attached to the shaft 10.
The gear 30a meshes with a wide drive gear 31 connected to a drive source (not shown). The electromagnetic clutch 30 is controlled by a controller (not shown), and transmits the rotational force of the drive source to the pair of registration rollers 5 through the ONL/ONL as required for sheet conveyance.

In FIG. 3, a sheet material S fed from a paper feed tray (not shown) is conveyed into a pair of guide plates 3 by a pair of slip rollers 2, and its tip reaches the nip portion of a pair of registration rollers 5 in a stationary state. Stops when inserted. As the slip roller pair 2 continues to rotate in this state, the sheet material S forms a loop, and due to the stiffness of the sheet material S with this loop in contact with the inner surface of the guide plate pair 3, the slip roller pair 2 is in a state where the sheet material S slips without being fed.

The registration roller pair 5 rotates in synchronization with the timing when the toner image on the photosensitive drum 1 rotates to a predetermined position, and feeds out the sheet material S. The fed-out sheet material S passes through the guide plate 6.
The toner image is guided to the photosensitive drum by a transfer charger 7, and separated after being transferred by a transfer charger 7. The toner image is further fixed by a fixing device (not shown).

The registration roller pair 5 of the copying machine configured as described above is configured so that the lateral position of the sheet material S can be controlled with sufficient accuracy. Furthermore, sheet material S
The important points for the accuracy of the position in the conveyance direction are that the tip of the sheet material S sufficiently enters the nip portion of the pair of registration rollers 5, and that the rotation of the pair of registration rollers 5 starts up sufficiently quickly. .

Normally, a pair of slip rollers is generally provided on the upstream side of the pair of rollers in the sheet conveyance direction in order to allow the leading edge of the sheet to sufficiently enter the nip portion between the pair of rollers.

For example, the slip roller pair 2 in FIG. 3 is configured so that the registration roller pair 5 applies a conveying force to the sheet material S to cause the sheet material S to enter the nip portion of the registration roller pair 5, which is not rotating. Even when stopped, the slip roller pair 2 always rotates. At this time, the slip roller pair 2 is in a slip state with respect to the sheet material S, and since the sheet material S is sandwiched between the guide plate pair 3, the slip roller pair 2 is in a slip state with respect to the sheet material S. The conveyance force is transmitted in the conveyance direction of the sheet material S, and the sheet material S
The tip is forcibly entered into the nip portion of the pair of registration rollers 5 by the above-mentioned conveying force.

In addition, although the guide plate pair 3 has a sufficient gap for the sheet material S to pass through, the gap is relatively narrow, so that the conveyance force applied to the sheet material S by the slip roller pair 2 is , acts mostly in the direction of movement of the sheet material S.

(C) Problems to be Solved by the Invention However, if the pair of registration rollers 5 is configured to move in a direction perpendicular to the conveyance direction of the sheet material S in order to prevent the sheet material S from being laterally displaced, as shown in FIG. As shown in the figure, since the sheet material S is also held by the slip roller pair 2 immediately before the registration roller pair 5, both roller pairs 2 and 5
If there is not enough slack in the sheet material S between
When the pair of registration rollers 5 moves in the direction of the arrow 29b, there is a problem that the sheet material S may be damaged as shown by arrow E, or may be conveyed in this state by the pair of registration rollers 5 and wrinkles may occur.

In order to prevent this, for example, if the slip roller pair 2 is moved in the same direction at the same time as the registration roller pair 5 is moved laterally, no problem will occur, but in this case, the mechanism is complicated and the device becomes large. There is a problem with putting it away.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus that eliminates problems such as breakage of the sheet material S by forming sufficient slack in the sheet material S when the sheet material is laterally moved by registration rollers. It is something.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned circumstances. For example, referring to FIGS. 1 and 2, the image forming section (1)
In an image forming apparatus having a pair of registration rollers for aligning the lateral deviation of the sheet material (S) being conveyed to the sheet material and displacing the sheet material in a direction perpendicular to the conveyance direction of the sheet material (S), The material (S) can be freely conveyed to the pair of registration rollers (5), and the pair of registration rollers (5)
) and the sheet material (S) conveyed from the slip roller pair (2) provided on the upstream side near the
), which guides the slip roller pair (2).
) and a pair of registration rollers (5), a pair of guide plates (40) disposed with an appropriate gap between them, and at least one guide plate (40a) supported so as to be openable and closable; and a pair of guide plates (40a) that can be opened and closed. The pair of registration rollers (5
), and a drive means (41) that opens when lateral displacement alignment is performed.

(f) Function Based on the above configuration, the sheet material (S) conveyed by the pair of slip rollers (2) is conveyed to the pair of registration rollers (5) while being guided by the pair of guide plates (40), and the leading end of the sheet material is conveyed by the pair of registration rollers (5). It enters the nip between the roller pair (5).

The sheet material (S) is moved horizontally by the pair of registration rollers (5).
In order to correct the lateral deviation, the drive means (41) operates to open the pair of guide plates (40). As a result, sufficient slack is generated in the sheet material (S) between the registration roller pair (5) and the slip roller pair (2), and the sheet material (S) This prevents defects such as damage and wrinkles from occurring.

Note that the above-mentioned symbols in parentheses are shown for reference to the drawings, and do not limit the structure of the present invention in any way.

B) Example An example of the present invention will be described below with reference to FIGS. 1 and 2. Components having the same functions as those shown in FIG. 3 are designated by the same reference numerals, and their explanation will be omitted.

In FIG. 1, between the slip roller pair 2 and the registration roller pair 5, there is an upper guide plate 40a and an upper guide plate 40a.
A lower guide plate 40 facing 0a with an appropriate gap
A guide plate pair 40 consisting of b is provided. At least one of the pair of guide plates 40, for example, the lower guide plate 40b
is configured to be openable and closable as described below. That is, the base of the lower guide plate 40b (the downstream end in this embodiment) is connected to the shaft 11 of the lower roller 5b of the registration roller pair 5.
It is rotatably attached to the arrow 4 by a spring (not shown).
It is biased in two directions. A dowel 40c is fixed to the inner surface of the upstream end of the lower guide plate 40b, and by pressing the dowel 40c against the upper guide plate 40a by the elasticity of the spring, there is a gap between the upper guide plate 40a and the lower guide plate 40b.
A necessary gap is formed for the sheet material S to pass through.

A short arm 40d that is integral with the lower guide plate 40b is formed at the base of the lower guide plate 40b, and the free end of this short arm 40d is connected to an actuator 41 of a solenoid (driving means) 41.
It is pivoted to a. Note that the registration roller pair 5 of this embodiment is also configured to be movable in the lateral direction (axial direction) like the registration roller pair 5 of FIG. 3, and the solenoid 41 also moves integrally with the registration roller pair 5. It is configured as follows. Furthermore, a guide plate 6 for guiding the sheet material S to the photosensitive drum 1 is disposed downstream of the pair of registration rollers 5.

A sheet material S fed from a paper feed cassette (not shown) disposed upstream of the pair of slip rollers 2 is conveyed by the pair of slip rollers 2 while being guided by a pair of guide plates 40, and its leading edge remains stationary. It enters between the nip of a certain pair of registration rollers 5. After this entry, the slip roller pair 2 continues to rotate, and after it is mechanically determined that the tip of the sheet material S has sufficiently entered the nip portion of the registration roller pair 5, the registration roller pair 5 is rotated at a slight angle. For example, the pair of registration rollers 5 rotates to the extent that the tip of the sheet material S protrudes from the nip portion of the pair of registration rollers 5 by about ioam, and the tip of the sheet material S
As shown in the figure, it is securely held by the pair of registration rollers 5.

Next, a voltage is applied to the solenoid 41 and the actuator 41a moves in the retracting direction, thereby rotating the lower guide plate 40b in the direction of the arrow 43 as shown in FIG. As a result, due to the rotation of the slip roller pair 2, the sheet material S between the slip roller pair 2 and the registration roller pair 5 is
A loop So is formed.

After a certain period of time has passed since the solenoid 41 is activated, when the controller (path shown) determines that the sheet material S has sufficiently slacked (loop S0) with respect to the lateral movement of the registration roller pair 5, the registration roller pair 5 5 is the lateral movement mechanism 9
(See FIG. 3) is operated, and the pair of registration rollers 5 and the sheet material S held therein are moved laterally to a predetermined position, and the adjustment of the lateral displacement of the sheet material S is completed. Thereafter, the pair of registration rollers 5 starts rotating to convey the sheet material S to the photosensitive drum 1 to transfer the toner image, and the toner image is further fixed by a fixing device (not shown) to complete image formation.

In the above embodiment, the lower guide plate 40b of one of the pair of guide plates 40 is rotated in the opening direction, but the upper guide plate 40a or both pairs of registration rollers 5 are rotated.
Alternatively, it may be configured to rotate. Furthermore, from the viewpoint of forming a loop SO after the leading end of the sheet material S is held between the pair of registration rollers 5, the pair of guide plates 40 not only rotate, but also guide in a direction in which the gap between the pair of guide plates 40 increases. The plate pair 4o may be configured to move in parallel. Furthermore, the lower guide plate 40b (or the upper guide plate 4
0a) is loop S. When the sheet material S rotates to form a loop S, the center of rotation is at the position of the sheet material S. The position is not particularly limited as long as there is no problem in forming the loop S0 and a sufficient space can be secured for forming the loop S0.

(g) As described in detail, according to the present invention, in an image forming apparatus having registration rollers and slip rollers that laterally move a sheet to be conveyed, a guide plate is provided after feeding a sheet material to the registration rollers. By making at least one of the pairs freely openable and closable to form a sufficient loop in the sheet material,
It is possible to adjust the displacement of the sheet material without causing problems such as damage and wrinkles to the sheet material.

Further, with the image forming apparatus to which the present invention is applied, it is possible to obtain a copy in which the image on the sheet material is formed at an accurate position both in the vertical and horizontal directions. This makes it possible to realize a copy in which the positional relationship between the two images is accurate, such as when obtaining multiple copies in which another image is superimposed on a copy on which an image has been formed.

[Brief explanation of the drawing]

FIG. 1 is a side view of a registration roller and its vicinity of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is an operational view, and FIG. 3 is a side view of a registration roller and its vicinity of a conventional image forming apparatus. FIG. 4 is a front view of the lateral movement mechanism for the registration rollers, and FIG. 5 is an operational view when the registration rollers are moved laterally. 5... Registration roller pair 9... Lateral movement mechanism,
30... Electromagnetic clutch 40... Guide plate pair,
40a... Upper guide plate 40b... Lower guide plate, 41... Renoid (driving means)

Claims (1)

[Scope of Claims] 1. An image forming device that aligns the lateral deviation of a sheet material conveyed to an image forming section, and includes a pair of registration rollers that displace the sheet material in a direction perpendicular to the conveyance direction of the sheet material. The apparatus includes: a pair of slip rollers which can freely convey the sheet material to the pair of registration rollers and which is provided on an upstream side near the pair of registration rollers; and a pair of slip rollers that guide the sheet material conveyed from the pair of slip rollers. A pair of guide plates in which the pair of slip rollers and the pair of registration rollers are arranged with an appropriate gap and at least one of the guide plates is supported so as to be openable and closable, and the pair of guide plates that can be opened and closed are aligned with the lateral displacement by the pair of registration rollers. An image forming apparatus comprising: a drive means that is opened at times.