JPH0637421Y2 - Pre-transfer-corotron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a pre-transfer corotron for an electrophotographic recording apparatus, and more specifically, a pre-transfer that pre-charges a toner image on a photoconductor before transferring it to a sheet. About corotron.

[Conventional technology]

In an electrophotographic recording apparatus, a latent image on a photoconductor is exposed by a latent image on the photoconductor, the latent image on the photoconductor is visualized by a developing device containing toner, and the visualized image is transferred onto a sheet to obtain a recorded matter. The toner image visualized by the developing device is combined with the paper, and the toner image is transferred to the paper by charging the paper to a high potential.

However, since the toner image on the photoconductor is polar,
In many cases, the toner image is not properly transferred when the transfer is performed. Then, in view of such a problem, in order to neutralize the charge of the toner image before transfer, a pre-transfer corotron is provided between the developing device and the transfer device,
There is known an electrophotographic recording device that uniformly charges a toner image before transfer. According to this apparatus, since the toner image and the photoconductor are neutralized and the attraction force is weakened, the toner easily adheres to the charged paper.

[Problems to be solved by the invention]

However, even if the above-mentioned problem related to toner that causes transfer failure is solved, transfer failure still occurs unless the sheet is properly charged by the transfer device.

Since the amount of electrification of a sheet varies depending on the material of the sheet and the internal resistance changes depending on the humidity of the atmosphere, it is not possible to always accurately electrify the sheet to a desired potential by the same sheet conveying device. In particular, when the paper is in a wet state, the internal resistance is small, and even if it is charged, the electric charge is grounded. Then, there is a problem that the amount of charge on the paper becomes small and the Coulomb force with the toner image becomes small, so that it becomes difficult for the toner to adhere. Further, if the humidity in the paper is non-uniform, the transfer density will also be non-uniform, and there is a problem that the transfer cannot be performed reliably.

Therefore, an object of the present invention is to solve the above problem, and to provide a pre-transfer corotron that guarantees reliable transfer regardless of the material of paper and the influence of atmospheric humidity. is there.

[Means and Actions for Solving Problems]

The above object of the present invention is to provide a pre-transfer corotron provided between a developing device and a paper chute of an electrophotographic recording device, in which a shield of the pre-transfer corotron is provided with an ion flow supply opening to the paper. Achieved by a pre-transfer corotron characterized in that the opening faces the ion flow receiving opening of the paper chute.

That is, the pre-transfer corotron charges the surface of the photoconductor and the toner image, and at the same time, the paper conveyed to the transfer portion is charged in advance, so that the paper is charged to a desired high potential by the transfer device. Therefore, transfer defects such as uneven density can be avoided, and reliable transfer is guaranteed.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of a first embodiment of a pre-transfer corotron arranged between a developing device and a transfer device around a photoconductor of an electrophotographic copying machine.

The pre-transfer corotron 1 is arranged close to the photoconductor 2, and a wire 4 having a length substantially equal to that of the photoconductor is stretched in a shield 3. Below the pre-transfer corotron 1, a paper chute 6 for guiding the paper 5 to the transfer device is arranged. The shield 3 of the pre-transfer corotron 1 has a first ion flow supply opening 7 facing the photoconductor 2 and a second ion flow facing the paper chute 6.
Of the paper chute 6
Also has an ion flow receiving attachment opening 9 facing the second ion flow supply opening 8, and the paper 5 conveyed in the paper chute 6 is exposed at the ion flow receiving opening 9. The paper chute 6 is grounded via the resistor 11.

To the wire 4 of the pre-transfer corotron 1, for example, a voltage of 2 to 5 KV RMS in which alternating current and direct current are superimposed is applied. The second ion flow supply opening 8 of the pre-transfer corotron 1 is a screen made of a mesh wire.
It is covered with 10, and this screen 10 has, for example, -300
DC voltage of ~ -1000V is applied. Where wire 4
The applied voltage of is a superposition of alternating current and negative (negative), and the applied voltage of the screen 10 is negative.

The electrostatic latent image formed on the photoconductor 2 is toner-developed by the latent image forming device, the photoconductor 2 rotates in the direction of arrow A, and the toner image is conveyed to the pre-transfer corotron 1. The toner image on the first is
Are charged through the ion flow supply opening 7. After development, the toner image is conveyed with a positive polarity, but since positive ions and negative ions flow toward the toner image from the wire 4, the toner image loses its polarity due to neutralization of charges. as a result,
The toner image is conveyed to the transfer device in a non-polar state.

On the other hand, the sheet 5 conveyed in the direction of the arrow B in the paper chute 6 and exposed from the ion flow receiving opening 9 is charged through the second ion flow supplying opening 8 by the discharge of the wire 4 of the pre-transfer corotron 1. At this time, since the second ion flow supply opening 8 is covered by the negative polarity screen 10, the negative ions easily flow from the wire 4 toward the screen 10, and the negative ions pass through the screen 10 to cause the paper to pass. 5, the sheet 5 is negatively charged.
The paper 5 is preferably charged to about -200 to -300 V by the pre-transfer corotron. Then, the charged sheet 5 is conveyed to the transfer device, is further charged with a negative polarity, and the toner image is transferred.

FIG. 2 is a schematic sectional view of a second embodiment of the pre-transfer corotron of the present invention. In the figure, the same symbols as in FIG. 1 represent the same members.

The feature of this embodiment is that the second ion flow supply opening 8 of the shield 3 is opposed to the paper chute 6 without being covered by the screen 10, and the paper chute 6 on the back side of the paper 5 (downward in the figure). DC voltage is being applied. A voltage of, for example, 300 to 1000 V is applied to the paper chute 6 and is positively charged. Positive and negative ions flow from the wire 4 of the pre-transfer corotron 1 through the first ion flow supply opening 7 toward the toner image on the photoconductor to neutralize the charge of the toner image and form the toner image. Make it non-polar. At the same time, the wire 4
Negative ions flow toward the paper chute 6 through the ion flow supply opening 8. The second ion flow supply opening 8 of the shield 3 faces the paper 5 exposed from the opening 9 of the paper chute 6, and the negative ions from the wire 4 flow toward the paper chute 6 on the back side of the paper 5. The recording surface of the paper 5 is negatively charged by negative ions. Although the paper chute 6 on the back side of the paper is positively charged, since the paper 5 is an insulator, even if the paper 5 and the paper chute 6 on the back side contact each other and are conveyed to the transfer unit,
The negative polarity on the recording surface side of the paper 5 is retained up to the transfer portion. Then, the paper 5 is conveyed to the transfer device and is further charged with a negative polarity, and the toner image on the photoconductor 2 is transferred.

In the above two examples, the toner image on the photoconductor has a positive polarity, but when the toner image has a negative polarity, the DC component of the voltage applied to the wire 4 has a positive polarity. , The screen 10 is applied in a positive polarity, the paper chute 6 is applied in a negative polarity, and the transfer device is also configured to charge the paper 5 in a positive polarity.

[Advantage of the Invention] According to the present invention, the pre-transfer corotron disposed between the developing device and the transfer device neutralizes the charge of the toner image on the photoconductor and protects the paper before transfer processing. Since it is charged in advance to compensate for the amount of charge before transfer, the transfer device keeps the paper at the desired potential and evenly regardless of the material of the paper and even if the paper absorbs moisture due to the influence of atmospheric humidity. Can be charged. Therefore, the paper is well charged,
Assured transfer is ensured without causing transfer defects such as uneven transfer density.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of the first embodiment of the present invention, and FIG.
It is a schematic sectional drawing of an Example. Reference symbols in the figure: 1 ... Pre-transfer corotron, 2 ... Photoconductor,
3 ... Shield, 4 ... Wire, 5 ... Paper, 6 ... Paper chute, 7 ... First ion flow supply opening 8 ... Second ion flow supply opening, 9 ... Guide member opening, 10 …… Screen, 11 …… Resistance

Claims (3)

[Scope of utility model registration request] 1. A pre-transfer corotron provided between a developing device and a paper chute of an electrophotographic recording apparatus, wherein a shield of the pre-transfer corotron is provided with an ion flow supply opening to a paper, and the opening is a paper. A pre-transfer corotron characterized by facing the ion flow receiving opening of the chute. 2. A mesh screen formed by setting a potential difference so that an ion flow from the pretransfer corotron is provided at the ion flow supply opening provided in the shield of the pretransfer corotron. The pre-transfer corotron according to claim 1 of the utility model registration claim. 3. The pre-transfer corotron according to claim 1, wherein a voltage having a polarity opposite to that of the pre-transfer corotron is applied to the paper chute on the back side of the paper.