JPS5984267A - Sheet conveyor - Google Patents

Abstract

PURPOSE:To prevent deterioration in picture quality due to irregular transfer, irregular printing, an omission of a picture, etc., even when a sheet is less flexible by equipping a sheet conveyor with a curling means which flexing a sheet in such a direction that it is wound easily around a drum. CONSTITUTION:This device consists of a cassette 40 and a member stored therein and is attachable between side plates 41 and 41 of a main copying machine frame. A sheet 47a sent from a paper feed roller 48 is caught and fed in a curling device 50 as shown by a broken line. While the sheet 47a enters an opening part 56 and exists from an opening part as a sheet 47b, the sheet is clamped between a large roll 54 and a belt 55 and curled along the circumferential surface of the large roll 54 to become arcuate as shown by a broken line. A guide 42 extends on the left side of a paper feed roller 70 to guide the sheet 47b to a resist roll 13. Therefore, the sheet 47b contacts the circumferential surface of a transfer drum 1 to prevent deterioration in picture quality.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a sheet conveying device that conveys a sheet to be wound around a drum, and more particularly, the present invention relates to a sheet conveying device that conveys a sheet to be wound around a drum, and more specifically, it relates to a sheet conveying device that conveys a sheet to be wound around a drum, and more particularly, it relates to a sheet conveying device that conveys a sheet to be wound around a drum. The present invention relates to a sheet conveying device equipped with a curling means that makes it easy to wrap the sheet around the circumferential surface of the drum.

(Prior Art) A drum to which the present invention is applied will be explained by taking, for example, a transfer drum of a color electrophotographic copying machine.

FIG. 1 shows the configuration of a conventional color electrophotographic copying machine, and in this figure, reference numerals 1 and 2 indicate a transfer drum and a photosensitive drum. The photoreceptor 2 rotates counterclockwise, and the charger 3 discharges electricity to uniformly charge the circumferential surface of the photoreceptor. The erase lamp 4 emits light as necessary,
Eliminates static electricity in non-image forming areas.

During this time, the optical image 5 of the original is projected onto the photoreceptor 2 via the optical system and exposed, and at this time the original image is color-separated by the filter 6. That is, an electrostatic latent image is formed corresponding to a color component image complementary to the specific color transmitted by the filter 6.

This electrostatic latent image is made visible by the developing device 7, and this visible image moves together with the photoreceptor 2. Note that while the developing device 7 is in operation, the other developing devices 8 and 9 are inactive.

Now, the transfer paper S is transferred to the cassette 11 by the paper feed roller 10.
from the separation roller pair 12 and the guide 12a.
and is sent to a pair of registration rollers 13.

The pair of registration rollers 13 align the leading ends of the transfer paper S and stand by in preparation for the clamp timing.

On the other hand, the transfer drum 1 is rotating clockwise while being pressed against the photoreceptor 2. Separation charger 4 discharges electricity inside and outside the transfer drum to eliminate static electricity from the transfer drum 1. Next, the peripheral surface of the transfer drum, which has been neutralized in this way, is precharged by discharging the prechargers 15 inside and outside the drum. The polarity is determined so that the outer peripheral surface of the transfer drum 1 has the opposite polarity to the toner image on the photoreceptor 2, that is, the same polarity as the electrostatic latent image.

A transfer paper S is placed on the circumferential surface of the transfer drum] 7 precharged in this manner in synchronization with the movement of the visible image on the photoreceptor 2.
The paper is fed by a pair of registration rollers]3. Then, the leading edge of the transfer paper S is held by a clamper (not shown),
After that, it wraps around the circumferential surface of the transfer drum 1 and moves.

The squeezing roller 16 acts so that the transfer paper S comes into close contact with the circumferential surface of the transfer drum 10 without wrinkles. The corresponding roller 17 supports the contact pressure of the squeezing roller 16 against the transfer drum 1 .

The transfer paper S wrapped around the circumferential surface of the transfer drum 1 is transferred to the photosensitive drum 2. The visible image on the photoreceptor drum 2 is superimposed on the transfer drum 1 at the contact portion between the two transfer drums. At the same time, the visible image is electrostatically transferred onto the transfer paper S by the action of the transfer charger 18. Even after the transfer, the transfer paper S continues to rotate together with the transfer drum 1, but at this time, the separation charger 14. The precharger 15 has stopped discharging, and the cleaner 19
has also stopped functioning.

On the other hand, the photoreceptor drum 2 has residual toner removed by the cleaning section 20, and is then neutralized by the static elimination charger 21, and then charged by the charger 3 in preparation for new use.

- The power-first system returns to the home position again, and filter 6
rotates 120 times counterclockwise.

At the same time as the newly charged part reaches the exposure part, a new scanning of the original is started and the same process as described above is carried out three times in total, so that a yellow visible image, a magenta visible image, and The unvisible images overlap each other to form a color visible image of the document.

The transfer paper having the color visible image is then subjected to charge removal by the separation charger 14, and then the clamp at the leading end is released. Next, the transfer paper S is separated from the transfer drum 1 by the separation claw 22 and guided by the guide 23 to the fixing section 2.
4, and is discharged out of the apparatus by a pair of discharge rollers 25.

The above is an overview of the color copying process, and the transfer drum 1 incorporated in this apparatus will be further explained with reference to FIG. 2.

FIG. 2 shows details of the transfer drum 1 that contacts the photosensitive drum 2 in rolling contact. In this figure, a shaft 2a for fixing the photoreceptor drum 2 is pivotally supported by an immovable side plate (not shown), and a gear 30 is substantially integrally formed on the right end of the photoreceptor drum 2. This gear 30 is connected to the drive system (not shown) by the arrow P.
be rotated in the direction. A photosensitive member is wound around the circumferential surface of the photosensitive drum 2.

The transfer drum 1 is mainly composed of a drum frame 1α having a notch shape in the center of a cylindrical body leaving a band-like shape in the axial direction, and a band-shaped remaining thickness portion connecting the annular remaining thickness portions at both ends in the axial direction. A clamper 31 for holding the transfer paper is provided. This clamper 31 is pivotally supported by the drum frame 1α via a shaft 31a. One end of this shaft 31α is bent into an L-shape, and as the transfer drum 1 rotates, the L-shaped bent portion engages with a con-i-roll cam (not shown) to open and close the clamper 31. ! Additionally, a dielectric film 32 is wrapped around the drum frame 1α so as to sufficiently cover the notch.

The gear 33 is substantially integrally formed at the right end of the transfer drum 2 and can mesh with the gear 30. Pinch circle diameter of both gears 30 and 33 and photoreceptor drum 2. The outer diameters of the transfer drums 1 are all the same.

On the other hand, the transfer drum 1 is independently rotatably supported at both ends by rocking plates 34 and 35, and the rocking plates 34 and 35 are pivotally supported by a common support shaft 36. And the tips 34α of the swing plates 34-, 35.

The transfer drum 1 can freely move toward and away from the photosensitive drum 2 by moving in the direction of the arrow 35α. Rocking plate 34.
35 is fixed via a stay 37 that is disposed so as to penetrate the transfer drum 1 in the longitudinal direction.

This stay 37 consists of three arms extending in the radial direction from the center of the transfer drum, and a transfer charger 18 and a separate charger precharger 15 are attached to the tip of each arm.

Now, in the above configuration, there is no problem when using transfer paper with a normal paper thickness, but if the paper is very thick or has high Clark stiffness, for example, official postcards or business cards, etc. When using a stiff transfer paper such as a transfer paper, the transfer paper does not stick tightly to the transfer drum circumferential surface and floats up, resulting in uneven transfer, image omission, or misalignment of the image, and the above-mentioned color electronic photography Copying machines involve multiple transfer processes, resulting in the problem of color misregistration. Furthermore, even if the leading edge of the transfer paper is gripped by the clamper, there is a problem in that an unstable conveying state occurs, such as floating up and breaking.

Such problems occur not only in electrophotographic copying machines but also in printing machines.

(Purpose) The present invention has been made to solve the above-mentioned problems of the prior art.
It is an object of the present invention to provide a sheet conveying device that can obtain uniform transfer or printing and clear images without causing image omission, image rubbing, or color shift, and can stably convey the sheet.

(Structure) The structure of the present invention will be described below based on one embodiment. 3 to 5 are a configuration diagram, a plan view, and a perspective view showing a sheet conveying device according to the present invention. In these figures, the device includes a cassette 40 and a cassette 4
The stiff transfer paper, which is a sheet fed from this device, is shown in FIG. It reaches the main body registration roller pair 13 through another guide 42 shown by a two-dot chain line.

Now, in FIGS. 3 to 5, the reference numeral 45 indicates a sheet mounting table, which can store sheets 47 such as official postcards and business cards according to their size, and has springs 46 from the bottom plate.
As a result, one end of the sheet 47 is constantly biased in the upward direction so that the sheet 47 is easily gripped by the paper feed roller 48. A paper feed roller 48c is located near the front end of the sheet mounting table 45 in the paper feeding direction and rotates in the direction of the arrow. The friction pad 49 is in contact with the paper feed roller 48 and is made of a member having a high coefficient of friction and has a function of preventing double feeding of the sheets 470. The sheet 47α sent out from the paper feed row 248 is held in the curling device 50 as shown by the broken line.

The curl device 50 is wound around three small rollers 51, 52 and 53 having centers at each vertex of a triangle, a dog roller 54 located approximately at the center of the triangle, and these four rollers. It consists of an endless belt 55. The dog roller 54 is rotating in the direction of the arrow, and the opening 56 formed between the belt stretched from the small roller 51 to the large roller 54 and the large roller 54 allows the sheet 47α sent out from the paper feed roller 48 to be smoothly caught in the mouth. It is formed in the position where it is engraved. The opening 57 formed between the belt passed from the dog roller 54 to the small roller 252 and the dog roller 54 is the exit of the sheet 47α, and the sheet 4 discharged by the rotation of the dog roller 54 is opened.
7h is formed so as to be transferable to the next conveyance path 58.

While the sheet (47α) enters the opening 56 and exits from the opening 57 as the sheet 47b, the large roller 54 and the belt 5
5, the sheet is curled along the circumferential surface of the thick roller 54, and the front and rear edges in the sheet feeding direction change into a curved shape (first chord arc shape in the figure) as shown by the broken line.

The conveyance path 58 includes rollers 59 and 60 arranged opposite to each other, and a plurality of endless belts 61 wrapped around these rollers.
and a guide 62 disposed above the endless belt 61. The endless belt 61 is rotating in the direction of the arrow and conveys the curled sheet 47b to the left in the figure. A roller 60 disposed on the left side of the conveyance path 58 in the figure further conveys the sheet 47b to the left in the figure in cooperation with a conveyance roller 62 that rolls into contact with the roller 60.

An upper guide 63 and a lower guide 6 are provided on the left side of the transport roller 62 in the figure, that is, on the main body insertion end 40α of the cassette 40.
4 are arranged opposite to each other in the vertical direction. And the lower guide 64
has an abbreviated cross-section, is swingably supported around a support shaft 65, one end 64α is locked to a spring 66, and the lower guide 64 always rotates clockwise. It is given.

The other end 64 of the lower guide 64. b, it is pressed against the lower circumferential surface of the paper feed roller 70 on the main body side at the cassette mounting position shown in the figure.

A guide 42 extends to the left side of the paper feed roller 70 on the main body side in the drawing, and is adapted to guide the sheet 47b to the pair of registration rollers 13 shown in FIG. 1.

In FIG. 1, the sheet 47b is the registration roller pair 13.
It is fed to the lower part of the transfer drum 1, and the clamper 31 (
(see Figure 2), the sheet 47h is curled in the shape of a waxing arc, as mentioned above.
The sheet 47h is in close contact with the circumferential surface of the transfer drum 10 like normal transfer paper, and rotates stably together with the transfer drum 1.

The curling device of this embodiment is constructed by a combination of an endless wide belt and large and small rollers, but the present invention is not limited to this system. It is also possible to use a combination of a rigid roller that is deeply bitten by a sponge roller, or it is also possible to use a system in which a large roller and a large number of small rollers are brought into rolling contact with the circumferential surface of the dog roller.

Although this embodiment has been described as being applied to a color electrophotographic copying machine, the present invention may be applied to a monochrome copying machine, and may also be prepared for use in a printing machine.

Furthermore, in this embodiment, the device is housed in a case and is formed to be detachable from the main body, but it may of course be incorporated into the main body and formed integrally with the main body. In this case, it goes without saying that a normal transfer paper mounting table and a stiff transfer paper mounting table are respectively incorporated.

(Effects) As is clear from the above description, the sheet conveying device of the present invention is equipped with a curling device that bends the sheet in a direction that makes it easier to wrap around the drum. Uniform transfer or printing and clear images can be obtained without occurrence of dropouts, image rubbing, or color shift, and stable conveyance can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a color electrophotographic copying machine, FIG. 2 is a perspective view showing a transfer drum incorporated in the copying machine, and FIG.
5 through 5 are a configuration diagram, a plan view, and a perspective view showing an embodiment of the present invention. 1...Transfer drum, 47.Strong sheet, 50...
・Curl device, S...Ordinary transfer paper.

Claims (1)

[Claims] What is claimed is: 1. A sheet conveying device for conveying a sheet wrapped around a circumferential surface of a drum to the drum, the sheet conveying device comprising a curling means for bending the sheet in a direction in which the sheet is easily wound around the drum.