JP2003307989A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus to stably and excellently form an image without causing the deviation of magnification error (deviation of image length). <P>SOLUTION: The image forming apparatus is equipped with a paper size detection means 42, an image data input means 43, a main motor 45 to drive a photoreceptor, and a control means 41 to change the rotating speed of the motor 45 between the transfer former part and the transfer latter part of paper. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer or the like, in which the number of revolutions of a main motor or scanner drive motor is variable.

[0002]

2. Description of the Related Art In image forming apparatuses such as copiers and printers, which are in widespread use, the size and weight of the image forming apparatus have recently been increasing year by year, and an increasing number of apparatuses do not include an intermediate roller between a paper feeding roller and a registration roller.

[0003]

However, in the above configuration, since the back tension (load) of the sheet feeding portion is directly applied while the transfer sheet is being conveyed by the registration rollers, the trailing edge of the sheet is different from that before passing through the sheet feeding portion. Later, the load on the registration roller changes and the slip ratio changes. Therefore, there is a drawback that magnification error deviation occurs in which the image length changes at the front half and the rear edge of the paper (the front half is short and the second half is long).

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to provide an image forming apparatus capable of performing stable and good image formation without magnification error deviation (image length deviation).

[0005]

In order to achieve the above object, the invention according to claim 1 provides a paper size detecting means, an image data inputting means, a main motor for driving a photoconductor, and a first half of the transfer of the paper. The image forming apparatus having the control means for changing the rotation speed of the main motor in the first and second sections is the most main feature.

According to a second aspect of the present invention, there is provided at least two sheet feeding units, a main motor for driving the photoconductor, and a main motor for each of the sheet feeding units in the first half and the second half of the sheet transfer. The most main feature is an image forming apparatus provided with a control unit for switching and controlling a change value of the rotation speed.

According to a third aspect of the present invention, there is provided an image including a paper size detecting means, a main motor for driving the photoconductor, and a control means for changing the rotation speed of the scanner driving motor in the first half and the second half of the transfer of the paper. The forming device is the most important feature.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an overall configuration diagram of the image forming apparatus. In FIG. 1, the image forming apparatus 1 is arranged in the approximate center of the main body of the image forming apparatus, and the paper feeding unit includes a cassette paper feeding unit 2 and a manual paper feeding unit 3. This image forming unit 1
A cassette paper feeding unit 2 is arranged immediately below the. The cassette paper feed unit 2 includes a paper feed cassette 21. Further, a manual sheet feeding section 3 is arranged on the right side surface. Note that another sheet feeding device can be added if necessary. Above the image forming unit 1, a reading unit 30 for reading a document is arranged with a space in between. Image forming unit 1 and reading unit 3
A space portion with 0 is formed as a paper discharge storage unit 4, and a recording medium on which an image is formed (hereinafter referred to as paper) is discharged and stored.

In the image forming unit 1, a charging device 6 for charging the surface of the photoconductor 5 around the drum-shaped photoconductor 5 and an exposure device 7 for irradiating the photoconductor surface with image information by laser light. A developing device 8 for visualizing the electrostatic latent image formed by being exposed on the surface of the photoconductor 5, a transfer device 9 for transferring the toner image developed on the photoconductor 5 onto a sheet, and remaining on the surface of the photoconductor after transfer. A cleaning device 10 for removing and collecting the toner is arranged. A fixing device 11 for fixing the toner on the sheet on which the toner image is obtained is arranged downstream of the image forming unit 1 (downstream in the sheet conveying path). The sheet that has passed through the fixing device 11 is discharged and stored in the discharged sheet storage section 4 by the sheet discharging device 12.

In the cassette paper feed unit 2, unused paper is stored in the paper feed cassette 21, and a spring 24 is provided so that the bottom plate 22 rotatably supported presses the uppermost paper against the paper feed roller 23. Pressurize. By rotating the paper feed roller 23, the uppermost paper is sent out from the paper feed cassette 21 and conveyed to the registration rollers 14. Registration roller 14
Is controlled so that the conveyance of the sheet is temporarily stopped and the toner image on the surface of the photoconductor and the leading edge of the sheet are rotated at a predetermined timing so that the positional relationship between the toner image and the front end of the sheet becomes a predetermined position.

Similarly, in the manual paper feed section 3, the manual paper feed tray is configured to be rotatable in the ⇔ direction so that the manual paper feed tray can be opened to the right side to replenish paper when used. A spring (not shown) applies pressure so that a rotatably supported manual feed bottom plate (not shown) presses the uppermost sheet against the manual feed roller 25. By rotating the manual feed roller 25, the uppermost sheet is sent out from the manual feed unit 3 and conveyed to the registration roller 14.

In the reading section 30, the contact glass 3
In order to read and scan a document (not shown) placed on the sheet 2, a reading traveling body 31 composed of a document illumination light source and a mirror reciprocates. The image information scanned by the reading traveling body 31 is read as an image signal into the CCD 33 installed behind the lens 31a. The read image signal is digitized and image-processed.

Based on the image-processed signal, a laser diode LD (not shown) in the exposure device 7 emits light to form an electrostatic latent image on the surface of the photoconductor 5. The optical signal from the LD passes through the well-known polygon mirror and lens to the photoconductor 5
Leading to. Although not shown, an automatic document feeder for automatically feeding the original onto the contact glass or a pressure plate for pressing the original is attached above the reading unit 3.

The image forming apparatus of this embodiment has a function as a so-called digital copying machine that scans and reads an original, digitizes and copies it onto paper as described above, and also an image of the original by a control device (not shown). The multifunctional image forming apparatus has a facsimile function of exchanging information with a remote place and a so-called printer function of printing image information handled by a computer on a sheet.

Images formed by any of the functions are all discharged and stored in one discharged sheet storage section 4. Output storage unit 4
The sheets stacked in the state that the image side is the lower side, and even if the processing order of the originals handled by copying, facsimile, and printer is printed from page 1 and printed, when the sheets are taken out from the discharged paper storage unit 4, The first page is at the top, which frees you from work such as aligning pages again.

FIG. 2 is a perspective view of the image forming apparatus shown in FIG. As can be seen from the figure, the copy / printed matter can be taken out from the paper discharge storage unit 4 from the front side of the apparatus, and the paper feed cassette 21 for supplying paper can be operated from the front side of the apparatus. When using manual paper feed, open the manual paper feed tray on the right side to add paper.

FIG. 3 is a control block diagram of the image forming apparatus according to the first embodiment of the present invention. Main control unit 41
Paper size detection unit 42 and image data input unit 4
3, a main motor drive circuit 44, a main motor 45, and a load 46 outside the photoconductor 5 are provided.

The paper size and the image data are transferred from the paper size detecting unit 42, the image data input unit 43 to the main control unit 41.
Is input, the timing at which the trailing edge of the sheet exits the sheet feeding unit is calculated according to the sheet size, and an appropriate number of rotations of the main motor 45 is output at a preset timing.

Here, the magnification error deviation in the sub-scanning direction (image length deviation) varies depending on the sheet conveying speed at the transfer portion, and consequently, the number of rotations of the main motor 45. If the main motor rotation speed is faster than the target, the latent image on the photoconductor 5 becomes longer, and conversely, if the rotation speed is slowed, the latent image on the photoconductor 5 becomes shorter.

That is, the proper image length can be controlled by controlling the proper main motor rotation speed in the first half and the second half of the sheet in the transfer section according to the sheet length. For reference, FIG. 4 shows the relationship between the image lengths of the first half and the second half of the paper in a general image forming apparatus.

FIG. 5 is a control block diagram of the image forming apparatus according to the second embodiment of the present invention. Main control unit 41
A sheet thickness detection unit 47, an operation unit 48, a main motor drive circuit 44, a main motor 45, and a load 46 outside the photoconductor 5 are provided.

When cassette paper feed or manual paper feed is selected by the operation unit 48, the proper main motor rotation speeds in the first half and the second half of the paper in the transfer unit set in advance by the selected paper feed position are It can be controlled by the paper feed point. That is, it is possible to reduce the magnification error deviation (image length deviation) depending on each paper feeding location regardless of the variation paper feeding load. For reference, FIG. 6 shows the relationship between the paper feed unit load and the magnification error deviation in a general image forming apparatus.

FIG. 7 is a control block diagram of an image forming apparatus according to the third embodiment of the present invention. Main control unit 41
A sheet size detection unit 42, a scanner traveling body drive circuit 49, a scanner drive motor 50, a main motor drive circuit 44, a main motor 45, and a load 46 outside the photoconductor 5 are provided.

The known first traveling body having the xenon lamp and the first mirror and the second traveling body having the second and third mirrors are moved by the rotation of the scanner drive motor 50. The speed of the second traveling body moves at half the speed of the first traveling body. Here, the magnification (image length) in the sub-scanning direction changes according to the moving speed of the scanner traveling body, and thus the number of rotations of the scanner drive motor 50. If the rotation speed of the scanner drive motor is faster than the target, the image becomes shorter, and if the rotation speed is slower, the image becomes longer.

That is, it is possible to reduce the magnification error deviation (image length deviation) by variably controlling the number of rotations of the scanner drive motor 50 in the first half and the second half of the sheet in the transfer section according to the sheet length. Become.

[0026]

As described above, according to the first aspect of the invention, since the main motor rotation speed can be variably controlled in the first half and the second half of the sheet, a good image with a small image length deviation is always obtained. Can be obtained.

According to the second aspect of the present invention, the main motor rotation speed can be variably controlled in the first half and the second half of the sheet in accordance with the sheet feeding section used, so that a good image with a small image length deviation can always be obtained. Can be obtained.

According to the third aspect of the present invention, since the scanner drive motor rotation speed can be variably controlled in the first half and the second half of the sheet, a good copy with a small image length deviation is always provided.
Images can be obtained.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus.

FIG. 2 is a perspective view of the image forming apparatus shown in FIG.

FIG. 3 is a control block diagram of the image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between image lengths of a first half portion and a second half portion of a sheet in a general image forming apparatus.

FIG. 5 is a control block diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a paper feed unit load and a magnification error deviation in a general image forming apparatus.

FIG. 7 is a control block diagram of an image forming apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

41 Main control unit (control means) 42 paper size detection unit (paper size detection means) 43 Image data input section (image data input means) 45 main motor

Claims (3)

[Claims] 1. A paper size detecting means, an image data inputting means, a main motor for driving a photoconductor, and a control means for changing the rotation speed of the main motor in the first half and the latter half of the transfer of the paper. A characteristic image forming apparatus. 2. A main motor for driving a photoconductor, comprising at least two paper feed units, and a change value of a rotation speed of the main motor at a first half and a second half of a sheet transfer in each paper feed unit. An image forming apparatus comprising a control unit that controls switching. 3. An image forming apparatus comprising: a paper size detection means; a main motor for driving a photoconductor; and a control means for changing the rotational speed of a scanner drive motor in the first half and the second half of the transfer of the paper. apparatus.