JPH0635251Y2 - Transfer device such as electronic copying machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a transfer device such as an electronic copying machine or a laser beam printer, and more specifically, it can obtain a clear image up to the rear end of a copy sheet without contaminating the copy sheet. The present invention relates to a transfer device such as an electronic copying machine.

[Conventional technology]

In an electronic copying machine, a copy can be obtained through each process of exposure, development, transfer and fixing.

Then, as a transfer device for transferring, a transfer corotron composed of a shield member opened toward the photosensitive drum and a discharge wire provided inside the transfer member is charged to transfer the transfer material brought into contact with the photosensitive drum to charge it. A corona transfer device that transfers a charged toner image on a drum onto a transfer material by electrostatic attraction is widely used.

In this corona transfer device, the transfer material must be in close contact with the photosensitive drum before being charged by the transfer corotron.
The toner moves in the space formed between the photosensitive drum and the transfer material, and a clear image cannot be obtained. For this reason,
A guide plate for guiding the transfer material to an appropriate position is provided.

An example of such a transfer device is shown in FIG.
What is disclosed in Japanese Patent No. 6560 is known.

In the figure, reference numeral 1 is a photosensitive drum, on the surface of which a toner image has been developed and which rotates in the direction of arrow B. Then, the transfer material is conveyed toward the photosensitive drum 1 by the guide plate 4,
The toner image on the photosensitive drum 1 is transferred to the transfer material by the discharge of the transfer corotron 6.

At this time, the discharge from the discharge wire 7 of the transfer corotron 6 to the transfer material is performed in a portion facing the opening of the conductive shield member 8 in FIG. 5, that is, in the transfer area C (shown by diagonal lines). The material needs to be in close contact with the photoconductor 6 before reaching the transfer area C. For this reason, the end of the shield member 8 on the transfer material entrance side is bent to form a halo baffle 8a, and the transfer area C is narrowed. Furthermore, the tip of the guide plate 4 is set at a position relatively higher than the transfer corotron 6.

As a result, the transfer material comes into close contact with the photosensitive drum 1 before being charged by the transfer corotron 6. Therefore, the transfer is performed in a state where the transfer material and the photosensitive drum 6 are in close contact, and a clear image is obtained.

Then, the transfer material after the transfer is peeled from the photoconductor drum by the peeling device 10, and then fixed by a fixing device (not shown).

[Problems to be solved by the invention]

However, in the above-described conventional transfer device, when the transfer material enters the transfer portion, the rear end of the transfer material is in a posture of being strongly bent to a high position by the guide plate 4, so that the rear end of the transfer material is guided by the guide plate 4. There is a problem in that the toner image is bounced off when it passes through the leading end of the sheet, and the toner image on the photosensitive drum 1 is not transferred to that portion.

In order to solve this problem, as shown in FIG. 6, a transfer device having a structure in which a metal or resin baffle 20 for supporting the transfer material is provided between the guide plate 4 and the transfer corotron 6. It has been known.

According to the configuration shown in FIG. 6, after the trailing edge of the transfer material passes through the leading edge of the guide plate 4, it temporarily comes into contact with the baffle 20 and the bending of the transfer material returns, so that the trailing edge of the transfer material suddenly falls off. Is prevented. If the baffle 20 is made of metal, it must be grounded to prevent noise. But in this case
When the transfer material is damp, the transfer current leaks through the baffle 20 and a transfer failure occurs.

If the baffle 20 is grounded via a high / low antibody, a constant voltage element or a bias power supply, the leak will disappear, but the baffle
The developing device and the photosensitive drum 1 by the bias voltage generated in 20.
There is a problem that the upper toner cloud adheres and stains the back surface of the transfer material.

Further, when the baffle 20 is insulated with a mylar 21 (shown by a broken line in FIG. 6) or when the baffle 20 is an insulator such as a resin, the upper surface of the baffle 20 is charged by charging due to friction with the transfer material and toner There is a drawback that dirt such as cloud adheres to the back surface of the transfer material.

An object of the present invention is to solve the above problems, prevent the transfer material from falling off, and perform good transfer without contaminating the surface of the transfer material.

[Means for solving problems]

In order to achieve the above object, the present invention arranges a transfer corotron facing a photoconductor, and forms a baffle by bending an upper end of a shield of the transfer corotron on a transfer material entrance side in a direction in which a transfer area is narrowed. A guide plate is provided that guides the transfer material between the photoconductor and the transfer corotron, and the tip of the guide plate is set at a position relatively higher than the transfer corotron, and the upper surface of the baffle and the side surface of the shield are provided. A transfer material support formed of an insulating resin is provided, and a plurality of ridges for restricting the maximum distance between the transfer material and the photoconductor are provided on the upper surface of the transfer material support in the transfer material entrance direction. It is characterized by being formed diagonally.

[Action]

The transfer material is guided by the guide plate and passes between the photoconductor and the transfer corotron, and the toner image on the photoconductor is transferred to the transfer material by the electrostatic force from the transfer corotron. At this time, since the tip of the guide plate is set at a position relatively higher than the transfer corotron, the transfer material is transferred in a state of being in close contact with the photoconductor in the transfer area. When the trailing edge of the transfer material passes through the tip of the guide plate, the trailing edge of the transfer material bounces down, but at this time, the trailing edge of the transfer material once contacts the transfer material bearing body and the impact of the bounce is softened. The toner image transferred to the material will not be separated from the transfer material. When transfer is performed, the transfer material moves while contacting the transfer material support, but since the transfer material support is made of insulating resin, the transfer material support is supported even when the transfer material is exposed to moisture. The transfer current does not leak through the body, and the transfer failure is prevented. When the transfer material bearing member is made of an insulating resin as described above, the transfer material bearing member may be charged by friction and dirt may be attached to the back surface of the transfer material. Is supported by a plurality of ridges formed on the upper surface of the transfer body support, so that the contact area between the transfer body support and the transfer material is small. Therefore, even when the transfer material supporting material is charged and impurities are attached to the transfer material supporting material, the amount of dirt attached from the transfer material supporting material to the transfer material is reduced, and the back surface of the transfer material is prevented from being dirty. Moreover, since the plurality of ridges are formed obliquely with respect to the transfer material intrusion direction, dirt does not stand out without continuously contacting the same portion of the transfer material.

〔Example〕

Hereinafter, the present invention will be described based on an embodiment shown in the drawings.
The same parts as those in the conventional example are designated by the same reference numerals.

FIG. 1 is a side sectional view of an electronic copying machine having an embodiment of the present invention.

In the figure, A is an electronic copying machine, which scans and exposes a document placed on a document table (not shown) to form an electrostatic latent image on the exposed portion 1a on the photosensitive drum 1, and the electrostatic latent image is formed. The developing device 2 develops with a developer containing toner to make a visible image, and then the image is transferred to a transfer material such as a sheet by the transfer device 3, and further heated and fixed by a fixing device (not shown) for copying. .

In the transfer device 3, 4 is a guide plate for guiding the transfer material supplied from the paper feed roller 5, and guides the transfer material to an appropriate position between the photosensitive drum 1 rotating in the arrow B direction and the transfer corotron 6. It is like this.

The transfer corotron 6 is opened so as to face the photosensitive drum 1, and discharges with a discharge wire 7 wired inside thereof to transfer the toner image on the photosensitive drum 1 to a transfer material. That is, the discharge wire 7 is applied with a voltage having a polarity opposite to that of the charged toner image, the transfer material is charged with a polarity opposite to that of the charged toner image, and is transferred by the electrostatic attraction.

Therefore, the opening facing the photosensitive drum 1 is the transfer area C, and the transfer material is kept in close contact with the photosensitive drum 1 before the transfer material is charged and transferred in this transfer area C so that good transfer can be performed. Further, the tip of the guide plate 4 is set at a position higher than the transfer corotron 6. In addition, the shield member 8
The transfer material entrance side of is bent in a direction to regulate the transfer area C and has a shape having a hello baffle 8a.

Here, a transfer material bearing member 9 which is between the shield member 8 of the transfer corotron 6 and the guide plate 4 and which covers the upper surface of the halo baffle 8a and the side surface of the shield member 8 and is made of an insulating resin having an L-shaped cross section is used. Is fixed. The transfer material support 9 regulates the maximum gap between the rear end of the transfer material and the photosensitive drum 1.

FIG. 2 is a plan view of the transfer material bearing member 9. The transfer material bearing member 9 has an upper surface of 0 to 45 with respect to the transfer material entering direction.
The plurality of rib members 9a are arranged at an angle of degrees to form the transfer material support 9
Are formed symmetrically with respect to the longitudinal direction.

The transfer material support 9 is formed by molding polypropylene, for example, and a rib member 9a having an R portion is formed on the surface in contact with the transfer material to form the rear end of the transfer material as shown in FIG. Hold.

The transfer material bearing member 9 may be fixed by using an adhesive or the like, or by screwing.

The transfer material is transferred to the guide plate 4 in the transfer device 3 configured as described above.
Then, the transfer material is conveyed in close contact with the photosensitive drum 1 by the guide plate 4, and the transfer is performed in the transfer area C.

Then, when the rear end of the transfer material passes the front end of the guide plate 4, the rear end portion of the front end of the guide plate 4 tends to bounce off from the warped posture of the transfer material due to the elasticity of the transfer material.

Here, the transfer material support 9 covered on the hello baffle 8a
Thus, the end portion of the transfer material advances while being held in contact with it.
Therefore, the end portion of the transfer material does not suddenly drop down, the transfer material in the portion facing the transfer area C is held in close contact with the photosensitive drum 1, and good transfer is also performed at the end portion of the transfer material.

At this time, since the contact between the transfer material support 9 and the transfer material is point contact by the R portion, even if the rib member 9a is charged by friction with the transfer material and dirt such as a toner cloud is attached, the transfer material surface The amount of adhesion to the surface of the transfer material becomes small, and the back surface stain of the transfer material can be practically ignored. Further, since the rib member 9a is inclined with respect to the transfer material entering direction,
The same portion of the transfer material as viewed from the direction perpendicular to the transfer material entering direction does not come into contact with the rib member 9a, and it is possible to prevent the transfer material surface from being contaminated in a tandem pattern.

In this embodiment, as shown in FIG.
Is regulated by the hello baffle 8a so that the transfer material is brought into close contact with the photoconductor drum 1 before reaching the transfer area C. When the end is separated from the guide plate 4, the rib member 9 provided on the upper surface of the halo baffle 8a effectively regulates the gap with the photosensitive drum 1, so that the transfer is performed with the transfer material of the photosensitive drum 1 in close contact. A clear image can be obtained over the entire area of the transfer material.

According to the experiment, the gap between the rib member 9a and the photosensitive drum 1 is 1
It is necessary to keep the range of ~ 3 mm, and further, the range of 1.5-2.5 mm is suitable.

Further, since the transfer material support 9 in this embodiment is made of resin and is non-conductive, even if the transfer material absorbs moisture under high humidity and its electric resistance value is reduced, the charge received by the transfer material is transferred. 9
There is no risk of transfer failure due to no leakage.

[Effect of device]

In the present invention, the transfer material bearing member, which is located between the photosensitive member and the transfer corotron and prevents the trailing edge of the transfer material from falling off, is an insulator and is in point contact with the transfer material.
Therefore, the amount of dirt adhering to the transfer material from the transfer material support is very small, and the dirt on the back surface of the transfer material is negligible, so that a clean copy can be obtained. Moreover, since the plurality of ridges are formed obliquely with respect to the transfer material intrusion direction, dirt does not stand out without continuous contact with the same portion of the transfer material.

[Brief description of drawings]

1 is a side sectional view of an electronic copying machine having an embodiment of the present invention, FIG. 2 is a plan view of a transfer material support, and FIG. 3 is a sectional view taken along the line I--I of FIG. FIG. 4 is a side sectional view of an electronic copying machine in a conventional example, FIG. 5 is an explanatory view of a transfer area,
FIG. 6 is a side sectional view of a main part of a transfer device in a conventional example. 1: Photosensitive drum, 2: Developing device 3: Transfer device, 4: Guide plate 5: Paper feed roller, 6: Transfer corotron 7: Discharge wire, 8; Shield member 8a: Hello baffle, 9: Transfer material support 9a: Rib member, 10: Peeling device A: Electronic copying machine, C: Transfer area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-47082 (JP, A) Actually opened 63-65063 (JP, U) Actually opened 60-184073 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A transfer corotron is arranged so as to face a photoconductor, and an upper end portion of a shield of the transfer corotron on a transfer material entrance side is bent in a direction in which a transfer region is narrowed to form a baffle. A guide plate that is guided between the transfer corotron and the transfer corotron and whose tip is set at a position relatively higher than the transfer corotron, and is formed of an insulating resin that covers the upper surface of the baffle and the side surface of the shield. And a plurality of ridges for restricting the maximum distance between the transfer material and the photoconductor are formed on the upper surface of the transfer material support at an angle with respect to the transfer material entering direction. Characteristic electronic copying machines and other transfer devices.