JPH02129676A - Image transfer device - Google Patents

Abstract

PURPOSE:To improve the quality of an image by arranging the bottom end part of a recording paper guide member below the uppermost part of a photosen sitive body and setting the upstream side position of a transferred recording paper carrying belt above the uppermost part of the photosensitive body. CONSTITUTION:The bottom end part 7a of the recording paper guide member 7 is arranged below the uppermost part of the photosensitive body 1 and the upstream side position 10a of the transferred recording paper carrying belt 10 in its carrying direction is set above the uppermost part of the photosensitive body 1. The recording paper which is in close contact with the surface of the photosensitive body 1 is carried to a transfer area S where a toner image formed on the photosensitive body 1 is transferred on the recording paper. The recording paper which is pressed with its resiliency on the surface of the photosensitive body 1 is carried and transferred at the same peripheral velocity as that of the photosensitive body 1, then attracted by electrostatic power of the carrying belt, and surely carried. Thereby, the quality of an image can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transfer device suitably used in, for example, an electrostatic copying machine. The present invention relates to a transfer device for transferring a converted toner image onto recording paper.

2. Description of the Related Art In conventional electrostatic copying machines, as a photoreceptor drum, which is rotatably provided on the machine body, is driven to rotate around its rotation axis, the surface of the photoreceptor drum is charged by a corona charger, and the exposure area is The photoreceptor drum is irradiated with light, and an electrostatic latent image corresponding to the information to be recorded is formed on the surface of the photoreceptor drum. This electrostatic latent image is developed into a toner image by a developing device.

Transfer involves transferring the toner image onto recording paper using corona discharge at the top of the photoconductor on which such a toner image has been formed, and then transporting the recorded paper by attracting it with electrostatic force using an endless conveyor belt. The device is known.

Among such transfer devices, in particular, in a transfer device in which a recording paper is inserted between a photoreceptor drum and a conveyance roller and are pressed against each other, the recording paper is pressed against the photoreceptor drum, and the photoreceptor drum is moved. The upper toner image is successfully transferred to the recording paper.

Problems to be Solved by the Invention However, in a transfer device that does not specifically insert a recording paper between a photoreceptor drum and a conveyance roller during transfer and press the recording paper into contact with the photoreceptor, it is difficult to accurately transfer the toner image on the photoreceptor. In addition, there have been insufficient efforts to clearly transfer the image onto the recording paper, and therefore the quality of the transferred image has not been maintained constant, resulting in deterioration of the image quality.

An object of the present invention is to provide a transfer device that can accurately and clearly transfer a toner image on a photoreceptor onto recording paper to improve image quality.

Means for Solving the Problems The present invention provides a transport mechanism in which a recording paper is transported above a photoreceptor, and a corona discharge is performed in a transfer area near the top 11 of the photoreceptor having a horizontal axis to remove the recording paper. In a transfer device that transfers a toner image on a photoreceptor to a photoreceptor, and conveys the transferred recording paper by attracting it to a conveyor belt using electrostatic force, the recording paper is guided above the recording paper from the upstream side of the transfer area. The lower end of the guide member is arranged below the top of the photoconductor, and the photoconductor is positioned upstream in the conveyance direction of the conveyor belt that electrostatically attracts the top surface of the recording paper after transfer on the downstream side of the transfer area. The transfer device is characterized in that it is arranged above the top of the transfer device.

Function According to the present invention, the lower end of the guide member provided on the upstream side of the transfer area is disposed below the top of the photoreceptor to guide the recording paper onto the photoreceptor. The recording paper guided in this manner is brought into close contact with the surface of the photoreceptor to a transfer area where the toner image formed on the photoreceptor is transferred to the recording paper. The recording paper is pressed against the surface of the photoreceptor by its elasticity and is moved at the same peripheral speed as the photoreceptor to perform transfer. In this way, the toner image on the photoreceptor is clearly transferred to the recording paper.

Further, according to the present invention, the upstream side in the conveyance direction of the conveyor belt that electrostatically attracts and conveys the transferred recording paper is disposed above the top of the photoreceptor. Therefore, the recording paper comes into contact with the conveyor belt, curves upward, and is electrostatically attracted, so that undesirable situations such as paper jams due to the recording paper not being attracted to the conveyor belt do not occur. The recording paper is transported to a fixing device for fixing the toner image transferred onto the surface of the recording paper while being reliably attracted to the transport belt.

Embodiment drawings are simplified cross-sectional views of a transfer device and the vicinity of a photoreceptor 1, which are an embodiment of the present invention. In this embodiment, for example, in a printer or the like, a right cylindrical photoreceptor 1 having a horizontal rotation axis is grounded and rotated in a rotation direction indicated by an arrow R. The photoreceptor 1 is charged by a main corona charger 2 and exposed in an exposure area 14 to light corresponding to the original image, such as laser light, to form an electrostatic latent image on the surface of the photoreceptor 1. The formed electrostatic latent image is developed into a toner image by the developing device 3. The toner image on the photoreceptor 1 is transferred onto the recording paper 15 guided in the direction of the arrow M by the guide member 7 in the transfer area S. The guide member 7 is made of plastic, for example. After the transfer, the recording paper 15 is conveyed in the direction of arrow N by the underlay section 10a of the conveyor belt 10 and guided to a fixing device (not shown).

The conveyor belt 10 is endless and includes a pair of conductive rollers 8.
．． 9 and is driven. The conveyor belt 10 has a conductive layer that contacts the rollers 8 and 9, and a dielectric layer formed around the conductive layer.

The conductive layer is made of a material such as metal or conductive rubber. The dielectric layer consists of an electrically insulating material.

A pair of rollers 8, 9. A corona charger 4 used for transfer is located near one of the rollers 8 near the photoreceptor 1.
is placed. This transfer corona charger 4 has an opening 16 facing toward the portion of the conveyor belt 10 wound around the roller 8 and the top V (1) of the outer peripheral surface of the photoreceptor 1, and The corona charger 4 is arranged on the upstream side in the transport direction N of the paper 15.
and has. The shield case 5 and the conductor 6 are connected to the photoreceptor 1.
The axis of rotation G of , thus extending perpendicular to the drawing. The shielding gate 5 is grounded, and the conducting wire 6 is powered by a power source (not shown).

As corona discharge is performed by the corona charger 4 disposed in this manner, the toner image on the photoreceptor 1 is transferred to the lower surface of the recording paper 15 being conveyed in the direction of arrow M. The portion of the conveyor belt 10 that is wrapped around the roller 8 is also charged by corona discharge by the corona charger 4, and the electrostatic force causes the recording paper 1 after transfer to be charged.
The upper surface of 5 is adsorbed to the underlay part 10a of the conveyor belt 10 and conveyed. Thereafter, the toner image on the recording paper 15 transported by the transport belt 10 is fixed by a fixing device (not shown).

In addition, the conveyance timing of the recording paper 15 is adjusted so that the photoreceptor 1
A registration roller 11 for transferring the upper toner image to an appropriate position on the recording paper 15 is mounted facing the guide member 7 on the upstream side in the conveyance direction M of the recording paper 15. The registration rollers 11 are composed of an upper registration roller 12 and a lower registration roller 13, and the recording paper 15 is held between the upper registration roller 12 and the lower registration roller 13, and the recording paper 15 is recorded toward the recording paper guide surface 7b of the guide member 7. The paper 15 is conveyed.

The upper registration roller 12 is made of metal, for example, and the lower registration roller 13 is made of rubber, for example.

The recording paper 1 is
5 is reliably caught in the longitudinal direction of the registration rollers 11 and conveyed onto the photoreceptor 1.

Next, the transfer device of the present invention and the arrangement around the photoreceptor 1 will be explained. The diameter shown below.

di d2, distance 11, 12, 13, 14. and angle θ1. It is assumed that all θ2 are positive values.

Rollers 8゜9 with diameters di and d2 having parallel rotational axes to the horizontal rotational axis G of the right cylindrical photoreceptor 1 are arranged at intervals of 14 between their rotational axes. A conveyor belt 10 is wrapped around it. The lower end 7a of the guide member 7 is located below the horizontal line H passing through the top U of the photoreceptor 1 by a distance 11. The tangent T of the photoconductor 1 and the roller 8 at the intersection point P of the extension line E of the recording paper guide surface 7b of the guide member 7 arranged in such a manner and the surface of the photoconductor 1.
Consider the intersection position A with the outer circumferential surface of the conveyor belt 10 that is wrapped around the conveyor belt 10. The guide member 7 is arranged so that the intersection value HA is below the intersection position C between the horizontal line W passing through the rotational axis B of the roller 8 and the outer peripheral surface of the conveyor belt 10.

The intersection position Q of the vertical line V passing through the rotational axis B of the roller 8 and the lower surface of the underlay part 10a of the conveyor belt 10 wound around the roller 8 is from the horizontal line H passing through the top U of the photoreceptor 1. is also placed 12 upwards. Further, with respect to a vertical line V passing through the rotation axis B of the roller 8, the rotation axis G of the photoreceptor 1 is disposed upstream of the recording paper 15 in the transport direction N by a horizontal distance I3.

Furthermore, the angle θ2 formed by the extension line E of the recording paper guide surface 7b of the guide member 7 and the horizontal line H passing through the top U of the photoreceptor 1 is 9
The intersection position A, the rotational axis B of the roller 8, and the intersection position Q on the outer circumferential surface of the belt 10 wound around the roller 8 are set to be smaller than 0 degrees, preferably 30 to 40 degrees. The guide member 7 is arranged with respect to the photoreceptor 1 so that the angle θ1 formed by the guide member 7 and the guide member 7 is smaller than 90 degrees.

According to the transfer device configured as described above and the arrangement around the photoreceptor 1, the recording paper 15 conveyed by the registration rollers 11 is moved onto the surface of the photoreceptor 1 by the action of the lower end 7a of the guide member 7. It is pressed with an elastic force of 15. In this way, the recording paper 15 is in close contact with the surface of the photoreceptor 1 on which the toner image is formed, and while rotating at the same speed as the circumferential speed of the photoreceptor 1 in the transfer eI area S, the toner is removed by corona discharge from the corona charger 4. The image is transferred from the photoreceptor 1 to the lower surface of the recording paper 15. Furthermore, the downstream end of the recording paper 15 in the conveyance direction after the transfer is guided downward by the underlay section 10a of the conveyance belt 10. Therefore, the recording paper 15 elastically moves the photoreceptor 1 in the transfer area S due to the elasticity of the recording paper 15.
Transfer is performed by pressing the surface of the photoreceptor 1 with as large a force as possible and moving it at the same speed as the circumferential speed of the photoreceptor 1.

For example, if the lower end portion 7a of the guide member 7 is located above the horizontal line H passing through the top U of the photoreceptor drum 1 without following the structure of the present invention, the recording paper 15 may overlap the surface of the photoreceptor 1 and the transfer area S. The toner on the photoreceptor 1 is attracted and adhered to the recording paper 15 at intervals. In such a toner adsorption method, the toner is not sufficiently adsorbed to the recording paper 15, resulting in image defects, which make the image unclear and degrade the image quality.

Also, for example, the intersection position Q of the vertical line V passing through the rotation axis B of the roller 8 and the lower surface of the underlay beam portion 10a of the belt 10
When the recording paper 15 is placed below the horizontal line H passing through the top U of the photoreceptor 1, the recording paper 15 after transfer comes into contact with the conveyor belt 10 and curves downward, and the recording paper 15 is reliably attracted to the belt 10. This can lead to undesirable situations such as paper jams. Therefore, the toner image transferred onto the recording paper 15 becomes distorted and unclear, and the image quality deteriorates.

Next, a specific example according to the research of the present inventor will be described. The diameter of the photoconductor 1 is 30 mm, the diameter d1 of the roller 8 near the photoconductor 1 is 12 mm, and the roller 9 that is far away from the photoconductor 1
The diameter d2 of the rollers 8 and 9 is set to 16 mm, and the distance between the rotation axes of the rollers 8 and 9 is set to 4 Q rn rn, and the vertical line V passing through the rotation axis B of the roller 8 and the rotation axis G of the photoreceptor 1 The horizontal distance 13 between the roller 8 and the vertical line V passing through the rotation axis B of the roller 8 is 8.0 mm. The distance 12 from the horizontal line H passing through the top U of is 0~
The photoreceptor 1 and the roller 8.9 are arranged so that the distance is 2.0 mm.

Moreover, the photoreceptor 1 and roller 8 arranged in this way,
9, the guide member 7 is arranged so that the distance 11 of the lower end 7a of the guide member 7 from the horizontal line H passing through the top U of the photoreceptor 1 is 0.5 to 2.0 mm, and the guide member 7 is The member 7 is arranged so that the angle θ2 between the extension line E of the recording paper guide surface 7b and the horizontal line H passing through the top U of the photoreceptor 1 is smaller than 90 degrees, preferably 40 degrees or less. Furthermore, a straight line connecting the above-mentioned intersection position A determined by the guide member 7 arranged in this way and the rotation axis B of the roller 8,
The guide member 7 is disposed with respect to the photoreceptor 1 so that the angle θ1 between the rotation axis B and the vertical line 2 is less than 90 degrees.

When the recording paper 1-5 is conveyed along with the registration rollers 11 to the guide member 7, the photoreceptor 1, and the rollers 8 and 9 arranged as described above, the recording paper 15 is transferred to the recording paper guide surface 7b of the guide member 7. The photoreceptor 1 is guided along the surface of the photoreceptor 1, and moved in the direction of the arrow M at the same peripheral speed as the photoreceptor 1. The recording paper 15 is transferred to the photoreceptor 1 in a state where it is pressed against the photoreceptor 1 with as large a force as possible due to the elasticity of the recording paper 15 in the transfer area S. Recording paper 15 on which transfer has been completed
The tip of the belt 1o is separated from the photoconductor 1 and is wound around the roller 8 at the intersection position A on the outer circumferential surface of the belt 1o.

Alternatively, it comes into contact with the conveyor belt 1o at a position lower than that, is well attracted by electrostatic force, and is conveyed to a fixing device (not shown).

In this way, the toner image on the photoreceptor 1 is clearly transferred onto the recording paper 15 by the transfer device of the present invention and is reliably conveyed to the fixing device.

The diameter described above as a specific example of the present invention, d3 d2
, distance 11.12.13.14, and angle θ1. θ2
These values are mutually determined as appropriate and are not limited to the numerical values of the specific examples. Furthermore, the present invention can be suitably implemented not only in printers but also in electrostatic copying machines and the like.

Effects of the Invention According to the present invention, the recording paper is pressed by its elasticity onto the photoreceptor on which the toner image is formed, and a clear image is transferred. Further, the recording paper after the transfer is attracted to the conveyor belt by electrostatic force and is surely conveyed without causing a paper jam. Therefore, transfer and conveyance are performed with constant good image quality.

[Brief explanation of the drawing]

The drawing is a simplified cross-sectional view of the transfer device and the vicinity of the photoreceptor 1 of the present invention. 1...Photoreceptor, 2...Main corona charger, 3...Developing device, 4...Corona charger for transfer, 5...Shield case, 6...Conductor, 7... Guide member, 7a...
- Lower end of guide member 7, 7b... recording paper guide surface, 8.
9...Roller, 10...Transport belt, 10a...
Lower rack portion of conveyor belt 10, 11... Registration roller, 12... Upper registration roller, 13... Lower registration roller, 14... Exposure area, 15... Recording paper, 16...
... Opening of transfer corona charger 4, dl... Diameter of roller 8, d2... Diameter of roller 9, D... Diameter of photoreceptor 1, G... Rotation axis of photoreceptor 1 , U...the top of the photoconductor 1, H...the horizontal line passing through the top U of the photoconductor 1, L...the laser beam, M, N...the conveyance direction of the recording paper 15, R...・Rotation direction of photoreceptor 1, S...Transfer area Agent Patent attorney Kei Saikyo Partial procedural amendment (method) March 14, 1999

Claims (1)

[Scope of Claims] A conveyance mechanism in which a recording paper is conveyed above a photoconductor performs corona discharge in a transfer area near the top of the photoconductor having a horizontal axis to transfer the toner on the photoconductor to the recording paper. transfer the image,
In a transfer device that conveys the transferred recording paper by adhering it to a conveyor belt using electrostatic force, the lower end of the guide member that guides the recording paper above the recording paper from the upstream side of the transfer area is connected to the photoreceptor. The conveyor belt is disposed below the top, and the upstream position in the conveyance direction of the conveyor belt, which electrostatically attracts the top surface of the recording paper after transfer on the downstream side of the transfer area, is disposed above the top of the photoreceptor. A transcription device characterized by the following.