JPH0484181A - Image recorder - Google Patents

Abstract

PURPOSE:To subject recording paper to transfer electrification in compliance with its size and to prevent the deterioration of a photosensitive body so as to obtain always good-quality images by providing a means for detecting the size of the recording paper to be passed and a means of varying the electrifying width of a transfer means and the transfer current thereof in accordance with the size of the recording paper detected by the detecting means. CONSTITUTION:The information on the side of the recording paper is transmitted from the recording paper size detecting sensor 25 via a bus 31 an I/O 22 to a CPU 19 for control when the recording paper 2 is set by mounting a paper feeder 1 to a base body 10. The CPU 19 for control sends a signal to a motor driver 26 via the bus 31 and the I/O 23 to control the rotation of a shutter driving motor 28 for transfer and to adjust the transfer opening of a transfer charger 8 in order to attain the transfer width meeting the size of the recording paper stored in a ROM 20. The CPU switches the transfer current so as to optimize the transfer current in corresponding to the transfer opening area. The fatigue of the photosensitive body is lessened in this way and the deterioration in images is lessened. The always optimum transfer is thus executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to control of the charging width of a transfer means and its transfer current in an image recording apparatus using an electrophotographic process.

(Prior Art) An overview of the configuration and operation of a laser printer as an example of an image recording device using an electrophotographic process will be described. The recording paper 2 is fed by a paper feed roller 17 in the six directions of arrows from a paper feed device l attached to the side surface of the printer main body 10, and is timed by a pair of register rollers 3 to be delivered to a drum-shaped photoreceptor. The latent image carrier is conveyed to a latent image carrier consisting of 4. The photoreceptor 4 is rotationally driven in a clockwise direction, the surface of which is charged by the charging charger 5, and irradiated with laser light from the laser optical system 6 to form an electrostatic latent image on the photoreceptor.

This latent image is made visible by toner when passing through the developing device 7, and this visible image is transferred to the recording paper 2 conveyed to the photoreceptor 4 by the transfer charger 8, and the visible image is The visual image is fixed by a fixing device 9. Then, the recording paper that has left the fixing device 9 is moved to the arrow B by the paper ejection roller 18.
It is discharged to the discharge section 11 in the direction.

On the other hand, residual toner is removed from the photoreceptor 4 after the visible image has been transferred by a cleaning device 13 having a cleaning blade 12 , and the charge is removed by a charge removal lamp 14 . The toner removed from the photoreceptor is collected by a collection roller 16 into a toner collection chamber 15 and stored therein.

(Problems to be Solved by the Invention) The image recording apparatus such as the laser printer described above is configured so that a plurality of types of recording paper 2 of different sizes are supplied from a paper feeding device 1.

In this way, conventional image recording apparatuses capable of printing on a plurality of recording paper sizes transfer and charge the entire photoreceptor regardless of the recording paper size. As a result, when printing on small-sized recording paper, the photoreceptor outside the paper is transferred and charged, so when printing multiple sheets of small-sized recording paper, the deterioration of the photoreceptor in the area outside the paper size accelerates, and when printing on large-sized recording When printed on paper,
The disadvantage was that small print marks remained and the image quality deteriorated.

It is an object of the present invention to eliminate such drawbacks, perform transfer charging in accordance with the size of recording paper, prevent deterioration of the photoreceptor, and always obtain high-quality images.

(Means for Solving the Problems) In order to solve the above problems and achieve the objects, the present invention provides an image recording apparatus using an electrophotographic process, which includes a means for detecting the size of recording paper to be passed, and The present invention is characterized by comprising means for varying the charging width of the transfer means and its transfer current based on the recording paper size.

(Function) The present invention variably controls the charging width and transfer current of the transfer means so that they become optimum values according to the recording paper size.
To solve the problem of leaving print marks due to different recording paper sizes.

(Embodiment) FIG. 1 shows a block diagram of a control section according to an embodiment of the present invention. In the figure, 19 is a microprocessor (hereinafter referred to as a control CP) that controls the overall operation of the image recording apparatus.
20 is RO which stores the operating program.
M also stores information that determines the transfer width and transfer current for the recording paper size, which will be described later. A RAM 21 is used as a large capacity random access memory. 22-2
4 are input/output interfaces (Ilo), each of which has a recording paper size detection sensor 25. Motor driver 26. A transfer high voltage power supply 27 is connected. 28 is a transfer shutter drive motor of the transfer charger 8.

FIG. 2 shows an example of the structure of the transfer charger 8.
1) is a top view, and FIG. 2(2) is a side view of the drive mechanism of the transfer shutter 29. This is because the sprocket 30 rotates as the transfer shutter drive motor 28 rotates.
The sprocket hole 29C of the transfer shutter 29 that meshes with this sprocket is formed, and the transfer shutter 29
is moved in the direction of arrow CC' (see FIG. 2 (1)) to a position that matches the various recording paper sizes. The transfer opening of the charge wire 8A is adjusted by the inclined portion 29A of the transfer shutter 29.

Next, the operation will be described. By attaching the paper feeding device l to the main body 10 of the laser printer shown in FIG. .A4, B5.A5, etc.) is bus 31. It is transmitted to the control CPU 19 via l1022.

This control CPU 19 uses a bus 31.2 to set a transfer width corresponding to the recording paper size stored in the ROM 20.
A signal is sent to the motor driver 26 via 1023 to control the rotation of the transfer shutter drive motor 28. When the recording paper is small in size, the drive motor 28 is rotated so that the transfer shutter 29 moves above the transfer charger 8 in the direction of arrow C (see FIG. 2 (1)).

As a result, the sprocket 30 rotates and engages with the sprocket hole 29C of the transfer shutter 29 while moving the transfer shutter 29 along the guide plate 29B. and move it. As a result, the wide portion formed by the inclined portion 29A of the transfer shutter 29 gradually narrows the transfer opening of the transfer charger 8. Then, the control CPU 19 controls the bus 31. A transfer current change instruction is issued to the transfer high-voltage power supply 27 via l1024 to switch the transfer current.

Transfer current information corresponding to the recording size is stored in the ROM 20, and based on the size information of the recording paper size detection sensor 25, the control CPU 19 reads out information corresponding to the recording paper size from the ROM 20, and supplies the transfer current to the transfer high voltage power supply 27. The transfer current is set by issuing an instruction. Further, the transfer high voltage power supply 27 is configured so that its output current can be switched by a control signal.

Also, when the recording paper is large-sized, the rotation direction of the transfer shutter drive motor 28 is reversed from that when the paper is small-sized.
The transfer opening area of the transfer charger 8 is widened by moving the transfer shutter 29 in the direction of the arrow C' force.

Of course, the control CPU 19 adjusts the transfer current accordingly.

The above-mentioned embodiment shows the case where the transfer aperture area is determined by a mechanical transfer shutter, but in addition to this, a plurality of charge wires 8A are prepared according to the recording paper size, and a control C
It can be used by switching according to instructions from the PU 19, or it can be provided with a switching terminal for energizing at a position that matches the recording paper size on one charge wire 8A, and supplying power by selecting the switching terminal for energizing according to an instruction from the control CPU 19. It is also possible to electrically control the transfer aperture area in this way.

(Effects of the Invention) As explained above, in the present invention, since the charging portion of the transfer charger can be changed according to the size (width) of the recording paper, it is possible to reduce fatigue of the photoreceptor and reduce image deterioration. . Furthermore, the transfer current is controlled according to the transfer width, making it possible to always perform optimal transfer.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a control unit according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of the configuration of a transfer charger, and FIG. 3 is a diagram showing the configuration of a laser printer as an example of an image recording device. It is a diagram. 2...Recording paper, 8...Transfer charger 8A
...Charger wire 19...Microprocessor (control CPU), 20...ROM, 21...
・RAM, 21-24...I/O interface (I
lo), 25... Recording paper size detection sensor, 26...
・Motor driver, 27...Transfer high voltage power supply, 28・
... Transfer shutter drive motor, 29... Transfer shutter, 29A... Inclined portion, 29B... Guide plate, 29C... Sprocket hole, 3o... Sprocket, 31... Bus. Figure 2

Claims (1)

[Claims] An image recording apparatus using an electrophotographic process, comprising means for detecting the size of recording paper to be passed, and means for varying the charging width of the transfer means and the transfer current based on the size of the recording paper detected by the detection means. An image recording device characterized by: