JPH01254986A - Image forming device - Google Patents

Abstract

PURPOSE:To separate a transferring material carrier without damaging it and to obtain an image of high quality in a long period by providing a transfer material separating means provided with a separating member between a transfer material and the transfer material carrier. CONSTITUTION:A transfer device 30 has a separating means 40. The separating means 40 has a separation claw supporting body 41 which is provided along the axis direction of a transfer drum 30D, and has a separation claw 42 with edging part; the separation claw is fixed to a supporting body as a separating part. Abutting rollers 45 and 46 are provided through proper supporting plates 43 and 44 on both edges of the supporting body 41. When a separation claw operating clutch is operated, the abutting rollers 45 and 46 abut against the cylindrical rings 31 and 32 of a transfer drum 30D and turn in the normal line direction of the transfer drum 30D with the leading edge of the separation claw downward by being guided by means of guiding sleeves 35 and 36 formed on the rings 31 and 32. Thus, stable separation can be performed regardless of environment nor the kind of a transfer material without damaging the transfer material carrier, and the image of high quality can be obtained in a long period.

Description

Detailed Description of the Invention - No. 1 The present invention provides a method for obtaining a transferred image on a transfer material by making a transfer material face an image carrier carrying a toner image and using a transfer means such as a corona charger. Regarding an image forming apparatus equipped with a transfer device that then separates the transfer material from the image carrier, in particular, the toner images of multiple colors formed on the image carrier are superimposed and suitably transferred onto the same transfer material, and then the transfer material is transferred. This can be suitably implemented in a color image forming apparatus that is equipped with a separating transfer device and that obtains a color image.

Conventionally, in an image forming apparatus such as an electrophotographic copying apparatus, a toner image is formed on an image bearing member such as an electrophotographic photoreceptor, and the toner image is transferred to a transfer material to obtain an image. teeth,
A transfer device is used to convey a transfer material to an image carrier carrying a toner image, bring it into contact with the image carrier, and transfer the toner image on the image carrier to the transfer material.

As shown in FIG. 13, the transfer device 10 includes a drum-shaped transfer material support 11 that is usually formed in a cylindrical shape, and a leading end of the transfer material P fed to the transfer material support 11. A transfer material locking portion 1 provided on the transfer material support 11 to stop the transfer material
2, and an opening 1 formed in the circumferential direction of the transfer material support 11.
3 (indicated by a broken line) and supports the transfer material P. It consists of a high resistance film-like transfer material carrying sheet (dielectric sheet) 14.

With the above configuration, the transfer material P supplied to the transfer material support 11 is moved in the earthwork direction that constitutes the transfer material locking section 12, and is moved to the tip by a locking claw (gripper) formed to be able to lock the transfer material. is gripped, and the subsequent portion of the transfer material P is supported on the transfer material carrying sheet 14. The transfer material P, which is firmly gripped by the gripper 12 and supported by the transfer material carrying sheet 14, comes into contact with the image carrier as the transfer material support 11 rotates. The transfer material P is disposed inside the transfer material support 11 and is charged with a polarity opposite to that of the toner by a corona discharger that applies an electric charge of opposite polarity to the toner to the back surface of the transfer material carrying sheet, or by using a conductive roller or the like. By applying a voltage, the toner image on the image carrier is transferred.

The transfer material P transferred in the above method is subjected to AC static elimination using a static eliminator (not shown) in order to weaken the adsorption force of the transfer material to the transfer material carrying sheet 14, and then the separating claw A is connected to the transfer material. The transfer material was separated from the transfer sheet 14 by placing it between the transfer material carrying sheets.

Conventionally, 5 to 9 separation claws A are provided, each separation claw A is arranged at regular intervals and at a certain angle, and each separation claw A is configured to achieve the same separation action and effect. Ta. Further, each separation claw A is brought into the vicinity of the transfer material carrying sheet 14 or in contact with the transfer material carrying sheet 14 by an operation signal from a control device (not shown) when the separation timing is reached.
The transfer material was separated from the transfer material carrying sheet, and then, upon completion of separation, it was returned to its original position by an operation cancellation signal from the control device.

- With such conventional separation means of a transfer device, it is extremely difficult to align the tips of the plurality of separation claws A at the same position with respect to the transfer material carrying sheet due to manufacturing and assembly problems. This was difficult, and the accuracy of the position of the tip of the separation claw varied, resulting in many cases where the transfer material could not be separated.

In addition, if the separating claws A contact the transfer material supporting sheet unevenly, the transfer material supporting sheet may be distorted at multiple locations.
As a result, the gap into which the separating claw A should enter between the transfer material carrying sheet and the transfer material becomes narrow, and there is a problem in that it becomes difficult to perform separation reliably.

If the separation claw is strongly pressed against the transfer material carrying sheet in order to ensure separation by the separation claw, the transfer material carrying sheet will be damaged, making it difficult to obtain a transferred image of good quality.
A problem occurred in that the dielectric sheet had to be replaced frequently.

As a result of conducting research experiments to solve the above problem, the inventors of the present invention found that the transfer material is more effective than the transfer material carrying sheet by having only one separating claw inserted between the transfer material carrying sheet and the transfer material. Even if the transfer material is electrostatically attracted to a transfer material carrier such as a transfer material carrier sheet, the transfer material can be very effectively separated from the transfer material carrier with one separation claw. I found something that could be done.

Also, from the perspective of separation probability, for example, when there are n separation claws for which the probability of making a minute m mistake is N, the probability that at least one separation claw will make a separation mistake is (n: 2 or higher natural number), where N<N”
Therefore, it can be seen that it is more effective to separate by l (1!).

The present invention has been made based on this new knowledge.

Therefore, an object of the present invention is to provide a transfer device with a separating means having a peeling member such as a separation claw, and to remove the transfer material held on the transfer material carrier extremely efficiently and to prevent damage to the transfer material carrier. It is an object of the present invention to provide an image forming apparatus that can separate images without causing damage and can obtain images of good quality over a long period of time.

Ruta's The above object is achieved by an image forming apparatus according to the present invention.

To summarize, the present invention provides an image forming apparatus in which a transfer material is conveyed and brought into contact with an image carrier carrying a toner image, and the toner image on the image carrier is transferred to the transfer material. a movable transfer material carrier capable of carrying a transfer material, a transfer means for transferring the toner image onto the transfer material, and separating the transfer material to which the toner image on the image carrier has been transferred from the transfer material carrier. In order to achieve this, the transfer material separating means is provided close to the transfer material carrier and has one peeling member inserted between the transfer material and the transfer material carrier. This is an image forming apparatus.

Support j Next, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

FIG. 10 shows an embodiment in which the image forming apparatus according to the present invention is implemented as a color electrophotographic apparatus. The photographic photosensitive drum 1 is uniformly charged by a charger 2, and a light image 3 corresponding to the image information is irradiated by an exposure means such as a laser beam exposure device, so that the electrostatic latent material is deposited on the photosensitive drum 1. An image is formed. The electrostatic latent image is visualized as a toner image on a photosensitive drum 1 by, for example, a mobile developing device 4.

The mobile developing device 4 includes four developing devices 4M and 4C14Y each housing four color developers: magenta developer, cyan developer, yellow developer, and black developer.
, 4B, and a guide (not shown) that holds these four developing devices and is movable in the horizontal direction. The mobile developing device 4 transports a desired developing device to a developing position facing the outer peripheral surface of the photosensitive drum 1, and develops the electrostatic latent image on the photosensitive drum.

The visible image, that is, the toner image, on the photosensitive drum 1 is carried by a transfer device 30, which will be described in detail later, and is conveyed by the transfer device 30 in the direction of the arrow in the figure, and then transferred to a transfer material that is brought into contact with the photosensitive drum 1. Transferred to P. The transfer material P is transferred to the transfer device 30 in synchronization with the image by the registration rollers 6a.
supplied to.

After the residual toner on the surface of the photosensitive drum 1 is cleaned by a cleaning device 20, the photosensitive drum 1 is subjected to a color image process again.

An embodiment of the transfer device i30 used in the color electrophotographic apparatus of the present invention will be described with reference to FIGS. 1 and 2. In this embodiment, the transfer device 30 is provided at both ends. It has a cylindrical ring 31.32 and a connecting part 33 that connects the ring 31.32. These cylindrical rings 31
．． 32 and the connecting portion 33 constitute a transfer material carrier made of a dielectric film, that is, a drum frame around which the transfer material carrier sheet 34 is wound.

In this embodiment, the transfer device 30 has a separation means 40.

The separating means 40 includes a separating claw supporter 41 provided along the axial direction of the transfer drum 300, and one peeling member fixed to the supporter 41, and in this embodiment, a separating claw with a pointed end. It has 42. A guide roller 42a may be integrally provided at the tip of the separation claw 42, as shown in FIGS. 4 and 5.

Also, according to this embodiment, at both ends of the support body 41 there are suitable support plates 43. as can be seen from FIGS. 1 and 4.
A roller 45° 46 is provided protruding through 44. The abutting rollers 45, 46 are activated when a separation pawl action clutch (not shown) is activated.

abutting the cylindrical ring 31, 32 of the transfer drum 300;
and a guide groove 35.36 formed in the ring 31.32.
A 0-separation pawl 4 guided by the 0-separation pawl 4 rotates the tip of the 1-separation pawl 42 downward, that is, in the normal direction of the transfer drum 30D.
The rotation mechanism No. 2 is not limited to such a configuration, and can also be achieved by a cam mechanism connected to the support plate 41.

A notch guide groove 37 is formed in the connecting portion 33 in order to facilitate the insertion of the separating claw 42 between the transfer material carrying sheet 34 and the transfer material P adsorbed and carried by the transfer material carrying sheet 34. Further, at the leading end of the transfer material supporting sheet 34, as shown in FIGS. 1 and 3, a cut 34a is formed along the notch guide groove 37 of the connecting portion 33 to the transfer material non-image area. .

Furthermore, to explain the transfer device 30, in this embodiment, the transfer device 30 transfers the transfer material P fed to the transfer device 30.
It has a transfer material adsorption means 5o for adsorbing and holding the transfer material on the transfer material carrying sheet 34.

The transfer material adsorption means 50 is provided inside the transfer drum 30D, as shown in FIG. Corona charger 51 and transfer drum 3
It has a conductive roller 52 provided on the outside of 0D. This conductive roller 52 is grounded, and the adsorption corona charger 51
In addition to serving as a counter electrode, it also functions to inject charge into the transfer material P and cause the transfer material P to be attracted to the transfer material carrying sheet 34 .

Preferably, the transfer material P is supplied so that the leading edge of the transfer material P overlaps the cut 34a of the transfer material carrying sheet 34 and does not enter the image area.

The transfer material P attracted by the transfer device 30 is transferred to the transfer charger 1
The photosensitive drum 1 is transported to the transfer area where the photosensitive drum 1 is placed.
In order to transfer the upper first color developer, for example, magenta toner, to the transfer material P, an electric charge having a polarity opposite to that of the toner is applied to the back surface of the transfer material carrying sheet 34 using a transfer corona charger 15. It will be done. By the time the transfer material to which the first color toner has been transferred comes to the position of the conductive roller 52 for the second time, the conductive roller 52 is released and moved to a position that does not disturb the toner image transferred onto the transfer material P, for example, the transfer material It is separated outwardly from the carrier sheet 34 by more than 2 mm.

Next, the second color toner image formed on the photosensitive drum 1 in synchronization with the transfer material onto which the first color toner has been transferred is transferred onto the transfer material P using the transfer corona charger 15. be done. Thereafter, toner images of four colors are transferred to the transfer material P in the same manner. Even when a plurality of transfer materials are carried on the transfer material carrying sheet 34, toner images of four colors are transferred to each transfer material in the same manner.

The transfer device 30 is provided with a pair of AC corona dischargers 16 facing each other with the transfer material carrying sheet 34 in between, in order to weaken the adsorption force of the transfer material to the transfer material carrying sheet after the transfer process is completed. The transfer material P and the transfer material carrying sheet 34 are neutralized.

According to this embodiment, in order to separate the transfer material P from the transfer material carrying sheet 34, as can be understood from FIGS. (not shown), abuts against the cylindrical ring 31.32 of the transfer drum 30D and is guided by a guide 11iI 35.36 formed in the ring 31.32. As a result, the tip of the separating claw 42 moves downward, that is, in the normal direction of the transfer drum 30D, toward the transfer sheet 3.
The separation claw 42 is rotated in four directions, and if the separation claw 42 is provided with a guide roller 42a, the guide roller 42a is pressed against the transfer sheet 34. Further, the guide roller 42a moves along the notched guide groove 37 of the connecting portion 33, and the tip of the separating claw 42 enters between the tip of the transfer material and the transfer material carrying sheet 34, so that the transfer material P is carried by the transfer material. It is separated from the sheet 34.

In order to prevent image blur due to peeling discharge that occurs when the transfer material P and the transfer material carrying sheet 34 are separated, it is preferable to perform AC corona discharge using the corona discharger 54.

After the transfer and separation steps are completed, the transfer material P is conveyed to the fixing device 18, where heat is applied to mix and fix the toner colors, and the paper is ejected to complete the copying.

According to another embodiment of the invention, the separating means 40 is provided with auxiliary peeling members on both sides of the central separating claw 42, as shown in FIGS. 5 to 7. Separation claw 42
One or more auxiliary separation claws 4 having a similar shape to
Separation means 40 of such configuration, in which 2b can be arranged.
In , the separation claw 42 is formed to protrude most toward the transfer drum 30r3, and the auxiliary separation claws 42b on both sides thereof are configured to become shorter toward both ends. Further, if provided, the guide roller 42a is provided integrally only with the separating claw 42 at the center.

Further, the tip of the auxiliary separating claw 42b can be configured to move within one plane and gradually separate from the surface of the transfer drum 30D as shown in FIG. 6, or as shown in FIG. It is also possible to construct the device so that the position of each separation claw can be varied three-dimensionally. The latter case is particularly effective when a weak transfer paper or the like is used as the transfer material, and when even more reliable separation is required.

According to the separating means 40 configured as described above, the separating claw 42 closest to the transfer material in the center first enters between the transfer material P and the transfer material carrying sheet 34, and as the transfer material P advances, the transfer material P Gradually, it is lifted up greatly, the separation area expands, and the separation claws 42b located on both sides of the separation claw in the center are also inserted between the transfer material P and the transfer material carrying sheet 34, and the one separation region further expands. Separation of the transfer material and the transfer material carrying sheet 34 is completed.

The auxiliary peeling member 42b can also be constructed by arranging a quadrant-shaped thin film member at a predetermined angle, as shown in FIG. 9, instead of the auxiliary separating claw 42b.

In this embodiment, the separation claw 42 is made of a 0.8 mm thick stainless steel plate coated with Teflon, and the auxiliary separation claw 42
A stainless steel plate with a thickness of 0.5 mm was used for b. especially,
The auxiliary peeling member 42b shown in FIG. 9 is preferably made of a metal plate or a flexible film (for example, PET), and if there is a burr or the like on the curved peripheral edge portion 42C of the tip, the conveyance of the transfer material will be deteriorated. It is preferable that the edge portion 42c be polished.

In the present invention, the separating claw 4 functions to separate the transfer material.
2, and the auxiliary separation member, for example, the auxiliary separation claw 42b,
This is used for the purpose of preventing the transfer material from sagging until it is sent from the transfer drum 5 to the conveyance member. Therefore, when an auxiliary separation claw is provided, depending on the position of the auxiliary separation claw 42b, it may get onto the transfer material and cause a separation error.

Therefore, the inventors have found a formula that can define the relative appropriate positional relationship between the auxiliary separating claw 42b and the separating claw 42.

FIG. 8(a) shows the behavior of the transfer material P as it is separated, and shows that when the transfer material P is lifted by d, it is separated by 2fL.

FIG. 8(b) shows the separating claw 42 and the auxiliary separating claw 42b placed in a three-dimensional space. θ is the angle formed by the tangent to the transfer drum 30D at the separation point and the separation claw 42, and it is assumed that the tip of the separation claw 42 is at the origin 0. The tip of the auxiliary separation claw 42b is located at a certain point Q (X+, V+) on the Xy plane.
Suppose it is in

Further, if point Q is a point on a -order function of y=ax (a: constant), the amount of rise d of the transfer material P is axltan θ. Here, since d and 2fL change in a similar manner as the paper progresses, z,:JL=axl tanθ:d. That is. When we experimentally determined d and the sentence, we obtained the results shown in Figure 1 below.

Table 1 In other words, since d/Kou = l/6, becomes.

Therefore, if the tip position of the auxiliary separation claw 42b is on the straight line with respect to the separation claw 42, a separation error will not occur.If there is more margin, it is sufficient to position it at the point where .

Another embodiment of the present invention is shown in FIGS. 11 and 12. In this embodiment, the transfer device 30 uses a transfer drum 34D consisting of a bias roller.

To explain further, the transfer drum 34D has a three-layer structure including an insulating layer 34a forming a surface supporting the transfer material P, a conductive layer 34b, and an internal insulating layer 34c. Also, transfer drum 3
In this embodiment, a groove 37 for guiding the separating claw is formed in the center of the surface insulating layer 34a of the 4D to assist the separating claw 42 to enter between the transfer material and the insulating layer 34a. The separation claw 42 and the auxiliary separation claw 42b are supported by a support shaft 60, and normally a spring 61 connected to the separation claw 42 moves the transfer drum 3.
It is biased away from the 4D surface.

When the time comes to separate the transfer material P to which the toner image has been transferred from the transfer drum 34D, a separation claw operation signal is output from a control device (not shown).

The separation claw solenoid 62 is powered on, and the transmission wire 6
3, the wire 63 transmits the movement to the separation claw 42 and the auxiliary separation claw 42b, and the separation claw 42 rotates toward the surface of the transfer drum 34D, enters the guide groove 37, and separates the transfer material P. Begin separation.

After the transfer material P is completely separated from the transfer drum 30D, the separation claw solenoid 62 is powered off and the separation claw 42 separates from the transfer drum 30D.

In each of the above embodiments, a transfer device equipped with a transfer drum wrapped with a dielectric sheet or a bias roller has been described, but a method using a belt-shaped transfer belt instead of the transfer drum is also possible. It is also possible to use a transfer device using, for example.

Furthermore, although the separation claw 42 described in connection with each embodiment is depicted at a position approximately at the center in the axial direction of the transfer drum, these drawings assume paper feeding based on the central position, and one side In the standard feed system, the separation pawl would be moved to another position.

In the above explanation, the present invention has been explained in relation to a color image forming apparatus, but the present invention can also be applied to other image forming apparatuses equipped with a transfer device, and the transfer device has a cylindrical shape as described above. It is not limited to.

As explained above, in the image forming apparatus according to the present invention, the transfer material is separated by a peeling member such as a separation claw, so that the transfer material can be reliably separated without mistakes in separation. This also solves the problem of limited separation certainty when multiple separation claws are used in the past, so the transfer material carrier is not damaged and is environmentally friendly. It has the advantage of being able to perform stable separation regardless of the type of transfer material and obtain images of good quality over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a transfer device used in an image forming apparatus according to the present invention. FIG. 2 is a perspective view showing the transfer drum frame of the transfer device shown in FIG. 1. FIG. FIG. 3 is a perspective view illustrating the relationship between the connecting portion of the transfer device shown in FIG. 1 and the transfer sheet. FIG. 4 is a side view illustrating the separation means used in the transfer device of FIG. 1. FIG. 5 is a plan view showing an embodiment of a separation means provided with an auxiliary separation member constructed according to the present invention. 6 and 7 are side views showing the positional relationship between the separating claw and the auxiliary separating claw. FIGS. 8(a) and 8(b) are explanatory diagrams illustrating the relationship between the lifting amount of the transfer material and the separation claw and the auxiliary separation claw. FIG. 9 is a perspective view showing another embodiment of a separating means with an auxiliary peeling member constructed according to the present invention. FIG. 1O is a schematic cross-sectional view of an embodiment of an image forming apparatus according to the present invention. FIG. 11 is a perspective view showing another embodiment of a transfer device constructed according to the present invention. FIG. 12 is a sectional view of the separating means portion of the transfer drum of FIG. 11. FIG. 13 is a perspective view showing an example of a conventional transfer device. l: Image carrier 30: Transfer device 300: Transfer drum 37: Guide groove 40: Separation means 42: Peeling member (separation claw) 42b: Auxiliary peeling member (auxiliary separation claw) 50: Transfer material adsorption means Fig. 3, Fig. 5 Figure 6 Figure 7 Figure 8 (b) Figure 9 Figure 11 B Figure 12

Claims (1)

[Scope of Claims] 1) In an image forming apparatus that conveys a transfer material and brings it into contact with an image carrier carrying a toner image, and transfers the toner image on the image carrier to the transfer material, a movable transfer material carrier capable of carrying a material, a transfer means for transferring the toner image onto the transfer material, and separating the transfer material to which the toner image on the image carrier has been transferred from the transfer material carrier. In order to do this, the transfer material separating means is provided close to the transfer material carrier and has a peeling member inserted between the transfer material and the transfer material carrier. image forming apparatus. 2) The image forming apparatus according to claim 1, further comprising a peeling auxiliary member disposed near the peeling member and on the downstream side in the moving direction of the transfer material carrier. 3) The image forming apparatus according to claim 1, wherein a guide groove is provided on the transfer material carrier at a position corresponding to the start of operation of the peeling member.