JPH06100871B2 - Transfer material transport device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer material conveying device for preventing disorder of copied images in an electrophotographic copying device.

2. Description of the Related Art Generally, in an electrophotographic copying apparatus, a toner image formed on the surface of an electrostatic latent image holder (hereinafter, referred to as a photoconductor) by an image forming unit transfers a transfer material (hereinafter, referred to as a transfer material) which is conveyed at a timing. It is electrostatically transferred to a transfer paper). At this time, the transfer paper is brought into close contact with the surface of the photoconductor by electrostatic attraction due to corona discharge at the time of transfer, and the charge having the opposite polarity to that of the toner remains, making it difficult to separate the transfer paper from the photoconductor. Become. Further, when the transfer paper after transfer is separated from the photoconductor and conveyed to the fixing device, when the transfer paper is separated from the photoconductor, the transfer paper is suddenly charged with electric potential between the guide plate and the fixing device member. As a result, a large gap is generated, and due to this potential difference, unfixed toner on the transfer paper is oscillated and scattered, and the copy image is disturbed. An example of this is shown in FIG. The toner image formed on the surface of the photoconductor drum 11 serving as an image carrier by the image forming unit is electrostatically transferred onto the transfer paper 18 which is conveyed at a timing. At this time, if the photoconductor is a drum and has a large diameter, the transfer paper 18 must be separated from the photoconductor drum 11 by using a separation charger of an electrical processing method or a separation belt of a mechanical processing method. When the transfer paper is separated without using the separation charger, the transfer paper is separated while being charged due to corona discharge during transfer, and when the guide plate is a conductor, if the transfer paper comes into contact with the guide plate. The charge of the transfer sheet, which is rapidly charged, moves to the guide plate and simultaneously disturbs the unfixed toner image.
Even when the guide plate is made of an insulator, depending on the environment, especially when the water content of the transfer paper decreases and the electric resistance value rises, a high electric charge is applied when the transfer paper is separated from the photoconductor, and the roll of the fixing device remains as it is. When approaching the member, the fixing device is usually charged by friction between the roll rotating members, but the potential is low, so a sharp potential gradient occurs in the small gap between the transfer paper and the roll member, and Disturb the image.

Problems to be Solved by the Invention In the conventional transfer paper separating / conveying device as described above, when the transfer paper on which the toner image is placed approaches the fixing device member, the unfixed toner is transferred to the transfer paper and the guide plate or the fixing device member. Due to the sharp potential gradient of the image, the image is disturbed, and the image is disturbed.

In view of the above problems, it is an object of the present invention to provide a transfer material transporting device that has a simple structure and stably maintains the transport of a transfer paper to obtain a high quality transferred image without being influenced by the surrounding environment. Is.

Means for Solving the Problems In order to solve the above problems, in the present invention, the transfer material is moved from the electrostatic latent image holding member to the fixing device and to the position where the tip of the transfer material is separated from the electrostatic latent image holding member. An endless conveyance auxiliary belt having a potential gradient is arranged, and the transfer material is separated from the electrostatic latent image holding member, and then means for gradually removing the charge potential of the transfer material is provided. is there.

Effect of the Invention With the above-described structure, the present invention gradually discharges the charging potential of the transfer material separated from the photosensitive drum by using the potential gradient of the conveyance assist belt to drop it near the charging potential of the fixing device roller member. The transfer sheet is prevented from abruptly generating a potential gradient when the transfer sheet approaches the roller member, so that the transfer toner image is prevented from swinging and scattering, and the occurrence of image disturbance due to this phenomenon is suppressed.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a copying machine of an embodiment of the transfer material / separation / conveyance apparatus of the present invention. In FIG. 1, reference numeral 11 denotes a photosensitive drum, which is an image bearing member, and is one in which an optical semiconductor layer such as selenium is provided on a conductive support such as aluminum. Usually, this conductive support is grounded. 12 is a corona charger for charging the photoconductor, 13 is exposure light from an exposure part including an exposure lamp and a lens, 14 is a developing section, 15 is a cleaning section, 16 is static elimination light from a static elimination lamp, 17 is fixing Container, 18 is a transfer material (paper), 19 is a corona charger, and 20 is a conveyance single belt of a conductor single layer.
Is a driven roller and 22 is a driving roller. 23 and 24 are power supplies, 2
5 is a guide plate and 26 is a peeling claw.

The operation of the copying machine in which the transfer material conveying device of the present embodiment configured as described above is arranged will be described below.

The photoconductor drum 11 rotates in the direction of the arrow, and the corona charger
The image is uniformly charged by 12 and an original image is irradiated by the image exposure light 13 to form an electrostatic latent image on the photoconductor drum 11. This image is visualized by the developing unit 14 to form a toner image. The toner image on the photoconductor drum 11 thus obtained is electrostatically transferred at the transfer position onto the transfer paper 18 that is conveyed in time with the toner image. The transfer paper 18 to which the toner image has been transferred is separated from the photosensitive drum 11 to the conveyance assist belt 20 by the peeling claw 26, is further guided to the fixing device 17, and the toner image is fixed on the transfer paper 18 by the fixing device 17. A copy image is obtained. On the other hand, the photosensitive drum continues to rotate, the residual toner on the surface is wiped off by means of a blade or the like in the cleaning unit 15, and then uniformly irradiated with the static elimination light 16 to eliminate static electricity, and copy. One cycle of the process for obtaining an image is completed, and a new process is prepared.

Next, FIG. 2 shows the main part of the carrying device according to this embodiment, and the description will be added with reference to this.

The transport assist belt 20 is composed of a single layer of conductor. In this example, an endless belt made of conductive rubber having a volume resistivity of 10 ⁶ Ωcm was used. Volume resistivity of 10 ⁴ to 10 ⁷ Ωcm, preferably 10
Other kinds of materials may be used as long as they are ⁵ to 10 ⁶ Ωcm. The conveyance assisting belt 20 is supported and rotated by the support rollers 21 and 22, and is pulled by tension applying means (not shown) such as a spring. The surfaces of the supporting rollers 21 and 22 with which the belt material comes into contact are conductive members. Transport auxiliary belt support roller
The supporting roller 22 of 21, 21 which is close to the fixing unit drives the conveyance assist belt 20 to rotate at the same speed as the photosensitive drum 11, and serves as a driving unit (not shown) for rotating this. I am in charge. Furthermore, these supporting rollers 21,2
A voltage is applied to the auxiliary auxiliary belt 20 from power sources 23 and 24 in order to apply a potential gradient to the auxiliary belt 20. The transfer paper 18 is gradually neutralized by being traced by the potential gradient of the transfer auxiliary belt 20 while being transferred by the transfer auxiliary belt 20, and then guided from the transfer auxiliary belt 20 to the fixing device 17 by the guide plate 25 to the fixing device 17. Is inserted. Therefore, the conveyance assist belt 20 does not electrostatically hold the transfer paper 18. Here, the guide plate 25 has a surface made of a non-conductive material, and is arranged so as not to have a sudden effect on the charging potential of the transfer paper 18. The fixing device 17 is a heat roller.
It consists of a combination of two rollers, 17A and backup roller 17B. Here, the heat roller 17A has a diameter of 30 mm, a thickness of 2 mm, and a thickness of 0.4 mm on the surface of an aluminum pipe.
Teflon resin coating is applied to reduce the surface temperature
A rod-shaped halogen lamp is inserted inside to keep the temperature at 180 ℃ and the applied current is adjusted. The backup roller 17B has a core metal covered with a heat-resistant silicone rubber having a thickness of 5 mm and has a diameter of 30 mm. These rolls 17A, B
Has the same peripheral speed as the traveling speed of the conveyance assist belt 20 and is pressed against each other and abutted against each other, and the toner image on the transfer paper 18 that is caught and inserted between them is fixed to the transfer paper 18. .

In order to clarify the effect of the present invention, it will be described in more detail by adding data. In the copying apparatus according to the present invention shown in FIG. 1, the process speed was 200 mm / sec, and the surface of the photosensitive selenium drum was charged to about +700 V by the corona charger 12. The surface 11 of the photosensitive drum was imagewise exposed to form a latent image, and the latent image was visualized as a toner image by the developing section 14.
The toner image was transferred onto the surface of the transfer paper 18 by the corona charger 19. Here, the volume resistance value of the transfer paper 18 is 10 ¹⁰ Ωcm and the basis weight is 64 g. The transfer paper 18 was separated from the photoconductor drum 11 by the peeling claw 26, then traveled on the conveyance assist belt 20 and guided to the fixing device 17, and the toner image on the transfer paper 18 was fixed. At this time, the roller 2 supporting the conveyance assist belt 20
Power supply 23,24 applied to 1,22 is not connected.
Was electrostatically floated. As a result, when the transfer paper 18 is separated from the photoconductor drum 11, its charging potential is about −10.
Since the backup roller 17B of the fixing device 17 was charged to about −400V, a sharp potential gradient was generated due to the potential difference between them, and the toner on the transfer paper 18 fluctuated and scattered. Distortion was recognized in the image discharged from container 17, and the resolution was poor. Next, a negative voltage of 1000 V is applied to the photosensitive drum 11 side and a negative voltage of 500 V is applied to the fixing device 17 side to the supporting rollers 21 and 22 of the conveyance assisting belt 20, respectively. The copy image discharged from 17 had no image distortion and had good resolution. This result is that the charge potential of the transfer paper 18 after being separated from the photoconductor drum 11 is gradually removed by the potential gradient of the conveyance assist belt 20, so that a large potential gap between the backup roller 17B of the fixing device 17 is generated. This is because it has been resolved.

EFFECTS OF THE INVENTION As described above, the present invention has an endless conveyance assisting belt having a potential gradient between the electrostatic latent image holder and the fixing device and to the position where the tip of the transfer material is separated from the electrostatic latent image holder. Place
After the transfer material is separated from the electrostatic latent image holding member, the charge potential of the transfer paper separated from the photoconductor drum is gradually removed by a means for gradually removing the charge potential of the transfer material, so that unfixed. It is possible to prevent scattering of the toner image and provide a high-quality copy image without image distortion.

[Brief description of drawings]

FIG. 1 is a side view of a copying machine on which a transfer material conveying device according to the first embodiment of the present invention is stacked, and FIG. 2 is an enlarged view of a main part of the transfer material conveying device according to the first embodiment of the present invention. FIG. 3 is a side view of a conventional transfer / conveyance unit. 11 …… photosensitive drum, 12 …… corona charger, 13 …… exposure light, 14 …… developing section, 15 …… cleaning section, 16 …… static elimination light, 17 …… fixing unit, 18 …… transfer material, 19: Corona charger.

Claims (2)

[Claims] 1. A transport device adapted to a device for physically or chemically transferring an image onto a transfer material, which is provided between an electrostatic latent image carrier and a fixing device and from the electrostatic latent image carrier. A means for arranging an endless conveyance auxiliary belt having a potential gradient to a position where the leading end of the transfer material separates, and gradually removing the charge potential of the transfer material after the transfer material is separated from the electrostatic latent image carrier. A transfer material conveying device equipped with. 2. The transfer material conveying device according to claim 1, wherein a potential difference is provided between two conductive rolls supporting a conductive auxiliary conveyance belt.