JP3116629B2 - Transfer device for image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus such as a copying machine and a printer, and more particularly to a transfer apparatus for transferring and transferring a transfer material of the apparatus by electrostatically attracting the transfer material to a transfer sheet.

[0002]

2. Description of the Related Art Among transfer devices of an image recording apparatus, a multi-transfer device transfers a single-color toner image formed each time a photoreceptor makes one rotation to a transfer material conveyed by electrostatically adsorbing a transfer sheet. The transfer of the single-color toner image in the multiple transfer device is repeated for each of yellow, magenta, cyan, and black, so that a full-color recorded image can be obtained.

As shown in FIG. 1, the multiple transfer apparatus transfers a toner image on a photoconductor 1 to a transfer sheet 10 on a transfer drum 2 following a cycle in which a sheet 4 as a transfer material is attracted to a transfer film. It is a conventional technique that the cycles are continuously executed while overlapping. That is, in order to increase the processing speed, the adsorption and transfer cycles are continuously performed while overlapping, and the discharge of the transfer corotron 13 of the first color is started before the discharge of the corotron 11 for electrostatic adsorption is completed. . The sheet 4 is conveyed toward the transfer sheet 10 by the pair of sheet feed rolls 9 after the alignment of the sheet conveyance. And transfer sheet 1
When the leading end reaches 0, the transfer sheet is adsorbed by the adsorbing corotron 11 and the opposing roll 8 within the circumference of the transfer sheet 10. .

In this apparatus, it is necessary to reduce the distance between the sheet feed roll 9 and the opposing roll 8 in order to make the apparatus compact. Further, the distance between the transfer corotron 13 and the opposing roll 8 also has to be shortened due to restrictions on the configuration. For the above reasons, the suction cycle and the transfer cycle are configured to overlap, and the following problems occur.

Since the distance between the pair of paper feed rolls 9 and the opposing roll 8 is short, if the paper 4 enters the opposing roll 8 and the paper feed roll 9 from an oblique direction during this time, an external force is applied to the paper 4 in the axial direction perpendicular to the transport direction. (Thrust force) is generated, and the thrust force acts on the transfer sheet 10 due to the reaction of the thrust force on the sheet 4. This thrust force is generated until the trailing edge of the sheet in the suction cycle passes through the sheet feed roll 9, and the transfer sheet 10 and the entire transfer sheet holding member are caused to have a thickness of 50 to 30 μm by the thrust force.
It moves in the μ axis direction. However, after the trailing edge of the sheet has passed through the sheet feed roll 9, the thrust force becomes zero, and the transfer sheet 10 and the entire transfer sheet holding member return to their original positions. In the returned state, the main transfer cycle and the next transfer cycle are continued.

There is a problem in that the transferred image under the condition of receiving the thrust force and the transferred image after the thrust force is released are displaced in color and appear on a copy. Also, when paper 4 that absorbs 7% or more of moisture is used,
The discharge current from the transfer corotron 13 is grounded via the opposing roll 9 located at the position opposing the attraction corotron 11 shown in FIG. 1, and the transfer of the toner image is disturbed, which adversely affects the image quality on the paper. There was also a problem of giving.

In order to solve the above two problems, the distance between the transfer position and the suction position on the transfer sheet 10 must be as large as possible. This eliminates the overlap between the sheet suction cycle and the toner image transfer cycle, and eliminates the leakage of the transfer current even when using a sheet having a high water content, which will be described later. Further, since the size of the entire image recording apparatus is limited, the distance cannot be increased.

The vibration caused by the thrust force generated at the sheet suction position of the transfer sheet 10 has a sufficient space between the sheet positioning unit and the suction position immediately before the sheet is conveyed to the transfer sheet 10, and the thrust is generated by the sheet loop between the positions. At the position where the force is reduced and the sheet 1 is attracted to the transfer sheet 10, the sheet 4
The transfer sheet 10 is free.
However, this method still cannot make the device compact.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image recording apparatus having a limited size, a transfer image defect due to a transfer image defect due to a thrust force of the sheet and a transfer current generated when the sheet absorbs moisture. It is an object of the present invention to provide a transfer device in which a defect of a transferred image due to leakage of an image is improved.

[0010]

The above object of the present invention is achieved by the following constitution. That is, in a transfer device of an image recording apparatus that transfers a toner image formed on an image carrier to a transfer material conveyed while being held by the transfer material carrier, the transfer material is transferred to the transfer material carrier prior to a transfer cycle. A transfer material holding cycle exclusively for electrostatic transfer, wherein the transfer material is held on the transfer material carrier only by electrostatic attraction, and the transfer material is transferred to the transfer material carrier during the cycle dedicated to the transfer material suction of the specific transfer material. Characterized in that it has a control device for controlling so as to reduce the adsorption speed of the liquid.

The transfer device of the image recording apparatus can select an appropriate suction mode according to the type (size and thickness) of the transfer material, the material (OHP paper, plain paper), and the water content of the transfer material. Can be possible. In particular, the mode according to the water content can be selected according to the use environment such as temperature and humidity in the multicolor image recording apparatus. In addition, when the above-described transfer material suction mode is selected as an application example, a low-speed suction cycle in which the transfer material transport speed is reduced and the transfer material is surely suctioned to the transfer sheet can be executed.

[0012]

According to the present invention, in the transfer cycle immediately after the adsorbing step, the image forming and developing steps are not performed, and only the adsorbing step is performed without applying the transfer corotron. In the cycle, the toner image is transferred to the transfer material. In this way, even if a thrust force acts on the transfer sheet when it is attracted, it does not overlap with the transfer cycle, so it is not affected.At the next transfer, it is relaxed, so there is no vibration of the transfer material and there is no displacement. Transfer image can be obtained. Further, even for a transfer material having a high water content, the overlap between the adsorption cycle and the transfer cycle is eliminated, and the leakage of the transfer current is eliminated.

Thus, even if the distance between the transfer material suction position and the toner image transfer position is small, the transfer material between the transfer material feed roll and the opposing roll at the position facing the suction corotron when the transfer material is conveyed to the suction position. A good image can be obtained even if the distance is small (even if the size of the entire image recording apparatus is limited). Thus, in the present invention, when the transfer material passes through the transfer position, a good image can be obtained by appropriately controlling the output of the transfer corotron in accordance with the transfer material.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a color laser printer to which the transfer material transfer drum of the present invention can be applied. In FIG. 1, the printer transfers a single-color toner image formed every one rotation of a photosensitive drum 1 onto a sheet 4 carried on a transfer material transporting transfer drum (hereinafter referred to as a transfer drum) 2, and transfers it to yellow, magenta, It is configured to obtain a full-color recorded image by repeating each of the cyan and black colors. The formation of a color image in this printer is specifically performed as follows.

First, from image information of a color image read by an optical scanning system such as a scanner, only image information relating to one of the four colors is extracted by an image processing means (not shown). Polygon mirror,
It is supplied to laser writing means 5 having a lens or the like inside. The laser writing means 5 exposes the photosensitive drum 1 so that the electrostatic latent image corresponds to the yellow color image.

The image of the electrostatic latent image is formed by a rotary developing unit 7 in which a yellow developing unit 7y, a magenta developing unit 7m, a cyan developing unit 7c, and a black developing unit 7k are held in four different directions. The unit 7 is driven to rotate so that a developing device corresponding to a color component of an electrostatic latent image formed on the photosensitive drum 1 is set at a developing position facing the photosensitive drum 1. A toner image is formed. Therefore, in FIG. 1, the yellow developing device 7y is set at the developing position, and a yellow toner image is formed.

On the other hand, the paper 4 is fed to the suction position of the transfer drum 2 by the positioning paper roll 9 at a predetermined timing synchronized with the formation of the toner image, and then transferred onto the transfer sheet 10 wound around the transfer drum 2. Adsorbed.
Adsorption of the paper 4 to the transfer sheet 10 is performed by an adsorption corotron 11.
This is performed by the electrostatic attraction generated by the discharge of. The sheet 4 thus held on the transfer drum 2 is sent to a position facing the photosensitive drum 1, that is, to a transfer section,
A yellow toner image is transferred from the photosensitive drum 1 with the discharge of the transfer corotron 13.

Next, the residual toner not transferred to the paper 4 on the photosensitive drum 1 is removed by the cleaning device 14. Thereafter, the photoconductor drum 1 is uniformly charged again by the charger 6, and a magenta toner image is formed on the photoconductor drum 1 through the same process as the yellow toner image. At this time, the transfer drum 2 continues to rotate while holding the sheet 4 on which the yellow toner image has been transferred, and the magenta toner image is transferred by superimposing the yellow toner image on the sheet 4 sent to the transfer unit again. Is done. Then, by repeating the same process for cyan and black, a color image in which the toner images of four colors are multiplex-transferred on the paper 4 is completed.

Sheet 4 on which the transfer of the black toner image has been completed
The electrostatic attraction acting between the transfer drum 2 and the transfer drum 2 is eliminated by the separation corotron 15, and is released from the transfer drum 2 by the separation claw 17. The transfer drum 2 from which the paper 4 has been peeled off is transferred to the transfer sheet 1 by the neutralizing corotron 18.
0, and the lifting member 19 and the cleaner 20
Thus, the paper dust and the like are cleaned, and the next sheet 4 is attracted. Further, the released sheet 4 is subjected to fixing of the toner image by the fixing device 22, and is discharged onto a discharge tray 24 by a discharge roller 23. This completes a series of recording operations for forming a color image.

FIG. 5 is a block diagram for controlling the sheet conveyance of this embodiment. In the transfer cycle immediately after the adsorption step in this embodiment, the image forming and developing steps are not performed, and only the adsorption step is performed. When the sheet passes through the transfer position, the output of the transfer corotron is appropriately controlled according to the sheet. That is, (1) In the case of four-color full-color transfer, as shown in FIG.
At the time of yellow (Y) → magenta (M) → cyan (C) → black (K), the adsorption and transfer cycles are continuously performed while overlapping, and three full colors (Y → M →
If C) is selected, the K cycle is controlled as a dummy cycle. In this way, the influence of the external paper force (thrust force) at the time of yellow (Y) image formation can be reduced.
It is also possible to use a method in which the transfer cycle immediately after the sheet 4 is attracted to the sheet 4 at the time of four-color full-color transfer is a dummy cycle, and the peeling cycle from the transfer sheet is delayed by one cycle.

(2) At the time of transfer of thick paper 4, as shown in FIG. 3, a suction cycle dedicated to thick paper is provided, and a transfer cycle immediately after suction is a dummy cycle . And this Dami
-There is a cycle , so the suction efficiency is improved by reducing the suction speed. The transfer cycle of FIG. 3 is automatically executed by the manual input or the detection of the thick paper by the thick paper detecting device in the apparatus when the thick paper 4 is conveyed.

(3) At the time of transfer when the water content of the paper is high, a dedicated suction cycle having a dummy is provided in the transfer cycle as shown in FIG. 4 so as to prevent the transfer current from leaking from the paper suction portion to lower the image. prevent. The moisture content of the paper 4 is measured by a method directly performed by a moisture content measuring device (not shown) provided in the middle of the paper-specific conveyance path, or by an environmental sensor for measuring environmental factors such as temperature and humidity in the image recording device. There is an indirect method. Further, the measurement of the moisture content of the paper 4 may be performed by providing an ammeter (not shown) on the ground connection line of the installation of the opposing roll 8 shown in FIG. In this case, as shown in FIG. 1, the photosensitive drum 1 is used to reflect the moisture content measurement result to the operation timing of an image forming apparatus for a series of image recording such as exposure, development, and transfer of a document. It is located upstream just before the suction part. Note that Da in the case in this embodiment is explained the case of using multiple transfer device, even during the transfer of the monochrome images, the water content of the sheet of paper 4 is high
By using the Mie cycle , it is possible to prevent the transfer current from leaking from the paper suction portion to lower the image.

(4) A dummy transfer cycle can be provided depending on the size of the sheet. That is, if the paper size is B5 or less, the suction cycle and the transfer cycle do not overlap, so that the transfer cycle immediately after the suction step does not need to be a dummy cycle. The above (1) to (4)
For the case of, in the same way as described in the case of (2) da
Since there is a mee cycle , in the suction-only mode, the suction speed can be reduced within a range that does not affect the operation timing of the image forming apparatus for a series of image recording such as exposure, development, and transfer of a document. That is, when the sheet 4 is sucked, the transfer (rotation) speed of the transfer sheet 10 is reduced to improve the efficiency of suction of the sheet to the transfer sheet, and after suction, the transfer speed of the transfer sheet is increased to increase the operation timing of the image forming apparatus. Can be adjusted to

Further, even if the distance between the opposing roll 8 and the paper feed roll 9 generated when the paper 4 is attracted is small, the deviation in the paper entry direction due to the paper thrust force is a dummy cycle.
It is eliminated by the overall transfer sheet 10 and the transfer sheet holding member while facilities, paper 4 is stably attracted onto the transfer sheet 10. Therefore, there is no image defect caused by the behavior. As shown in FIG. 3 for the moisture content of the paper 4 and as shown in FIG. 4 for the thickness of the paper,
When the paper is OHP paper, the thick paper detection shown in FIG.
The value is the same by changing to P paper detection. As described above, in the case of OHP paper, the feeding cycle of the paper size is shorter than the distance between the suction position and the transfer position, and in the case of A4 short feed, the suction cycle and the transfer cycle do not overlap from the paper size. It is not necessary to make the transfer cycle immediately after the adsorption step a dummy cycle.

According to this embodiment, the allowable range of sheet feeding on the transfer sheet is expanded, and the range of used sheets is expanded. In addition, by using the dummy cycle , it is possible to reduce the output of the suction corotron and reduce the capability of the high voltage power supply when the paper is attracted to the transfer sheet by reducing the paper transport speed. Further, the required value of the mechanical strength of the transfer sheet holding member can be reduced, and the allowable width for the oblique feeding of the sheet is increased. In addition, there is no longer any restriction on the design of the suction section and the design restrictions between the transfer position and the suction position due to the external force of the paper posture, and the image recording apparatus can be made compact.

According to Japanese Patent Application Laid-Open No. H1-53084, in order to ensure that thick paper is attracted to a transfer sheet, a transfer operation of the first color on a reciprocating transfer belt is performed before the first color transfer operation. A transfer paper transport control method of a color recording apparatus for making a reciprocating movement of a thick paper sheet is described. Comparing the invention described in the above publication with the invention described in this embodiment, the invention described in the above publication also performs the suction operation with the transfer corotron, whereas the invention described in the present embodiment shows that the transfer corotron does not attract paper. Is not performed, the paper is absorbed only by the adsorption corotron,
Moreover, by lowering the suction speed, the suction of the sheet onto the transfer sheet is ensured.

[0027]

According to the present invention, by providing a suction-dedicated cycle when a sheet is attracted to a transfer sheet, (1) types of usable paper (size, thickness, etc.) can be compared with the prior art. (2) Expansion of usable range of paper moisture content,
(3) It is possible to improve image defects due to movement that occurs at the time of paper suction, and (4) to make the image recording apparatus compact.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a transfer device of an image recording apparatus according to an embodiment of the present invention.

FIG. 2 is a time chart showing a suction and transfer cycle of a transfer device during four-color full-color transfer according to one embodiment of the present invention.

FIG. 3 is a time chart showing a suction and transfer cycle of a transfer device during transfer to a cardboard sheet according to an embodiment of the present invention.

FIG. 4 is a time chart showing a suction cycle and a transfer cycle of a transfer device at the time of transfer when the water content of a sheet according to an embodiment of the present invention is high.

FIG. 5 is a control block diagram of a transfer device according to one embodiment of the present invention.

FIG. 6 is a time chart showing a suction cycle and a transfer cycle of a transfer device at the time of conventional four-color full-color transfer.

[Explanation of symbols]

2 transfer drum, 4 paper, 8 facing roll, 9
Paper feed roll, 10 transfer sheet, 11 adsorption corotron, 13 transfer corotron, 17 peeling claw,
20 cleaner

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-109381 (JP, A) JP-A-2-207284 (JP, A) JP-A 5-35044 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 15/16 G03G 15/01 114 G03G 21/00 370

Claims (1)

(57) [Claims] 1. A transfer device of an image recording apparatus for transferring a toner image formed on an image carrier to a transfer material which is held by a transfer material carrier and conveyed to the transfer material carrier prior to a transfer cycle. Transfer material is adsorbed
The transfer material has a dedicated cycle to make the transfer material
It is held on the transfer material carrier only by suction and
The transfer is performed during the transfer material exclusive cycle of the transfer material.
A transfer device for an image recording apparatus, comprising: a control device that controls a suction speed of a transfer material to a material carrier to be reduced.