JP2001356547A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of realizing the prolongation of the life of a specified image forming unit and the miniaturization of the device. SOLUTION: A printer 10 (image forming device) is equipped with a rotatable intermediate transfer belt 12 (intermediate transfer body), and plural image forming units 20Y, 20M, 20C and 20K (image forming means) proximately arranged at a specified pitch along the belt 12 and respectively forming different color images on the belt 12, and the units 20Y, 20M, 20C and 20K are provided with plural elements (developing devices 28Y, 28M, 28C and 28K and cleaners 32Y, 32M, 32C and 32K) in an arranging direction along the belt 12. Out of the elements (developing device 28K and cleaner 32K) of the image forming unit 20K positioned nearest to an end side in the arranging direction of the units 20Y, 20M, 20C and 20K, the element (cleaner 32K) on a side where the image forming unit is not adjacent is made large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called tandem type color image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, a so-called tandem type color image forming apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-28294, in which a plurality of image forming units each containing toner of a different color are arranged side by side along an intermediate transfer belt. It has been known.

In this type of image forming apparatus, the size of each image forming unit is reduced, and the image forming units are arranged at an equal pitch and a required minimum pitch along the intermediate transfer belt, so that the size of the apparatus is reduced. In order to reduce the size of each image forming unit, the size of a cleaner, a developing unit, and the like, which are elements of the image forming unit, is reduced to achieve miniaturization.

[0004]

However, in order to extend the life of the image forming unit, the cleaner blade normally fixed in the cleaner is elastically supported by a spring, and the amount of toner stored and consumed in the developing device is increased. In order to accommodate them, it was necessary to increase the size of the cleaner and the developing device. However, when the element size of all the image forming units is increased, there is a problem that the pitch is increased and the size of the entire apparatus is also increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of extending the life of a specific image forming unit and reducing the size of the apparatus.

[0006]

According to one aspect of the present invention, there is provided an image forming apparatus comprising: a rotatable intermediate transfer member;
A plurality of image forming means arranged in close proximity at a predetermined pitch along the intermediate transfer body to form images of different colors on the intermediate transfer body, respectively, the image forming means comprising: In the image forming apparatus having a plurality of elements in the arrangement direction along the image forming apparatus, among the elements of the image forming unit located at the endmost side in the arrangement direction of the image forming unit, the side on which the image forming unit is not adjacent Is an enlarged element.

In the image forming apparatus of the present invention, of the elements of the image forming means located at the endmost side in the arrangement direction, only the elements on the side not adjacent to the image forming means are enlarged, and the image forming means is adjacent. Since the size of the element on the side is not increased, the arrangement pitch of the image forming means can be made equal pitch and the necessary minimum, and the size of the apparatus can be reduced.

[0008] In the image forming apparatus of the present invention, it is preferable that the image forming means having the enlarged element is an image forming means for forming a black image.

In the image forming apparatus of the present invention, the enlarged element is preferably a cleaner. This makes it possible to elastically support the cleaner blade of the cleaner, which is pressed against the photosensitive member of the frequently used black image forming unit, by the spring, thereby extending the life of the image forming unit.

Further, in the image forming apparatus of the present invention, the enlarged element may be a developing device. This makes it possible to increase the space for accommodating the black toner in the developing unit of the frequently used black image forming unit, thereby extending the life of the image forming unit.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a tandem digital color printer (hereinafter, referred to as an embodiment) of the present invention.
FIG. 1 is an overall configuration diagram of a “printer” 10.

The printer 10 has an intermediate transfer belt 12 at a substantially central portion inside the printer. Intermediate transfer belt 12
Is supported by the outer peripheral portions of the rollers 14, 16 and the driving roller 18, and is driven to rotate in the direction of arrow A.

Below the lower horizontal portion of the intermediate transfer belt 12, yellow (Y), magenta (M), cyan (C),
Four image forming units 20Y, 20M, 20C, and 20K corresponding to the respective colors of black (K) are arranged closely at a constant pitch along the intermediate transfer belt 12. This pitch is defined to be an integral multiple of the circumference of the drive roller 18, and color misregistration can be prevented when toner images of each color are superimposed on the intermediate transfer belt 12 as described later.

Each of the image forming units 20Y, 20M, 20C,
20K is a photosensitive drum 22Y, 22M, 22C, 22
K. Each photoconductor drum 22Y, 22
The chargers 24Y, 24M, 24C, which uniformly charge the surfaces of the photosensitive drums 22Y, 22M, 22C, and 22K around the M, 22C, and 22K in the rotation direction.
24K, print heads 26Y, 26M, 26C and 26K for forming an electrostatic latent image by exposing the uniformly charged photosensitive drum surface in accordance with each color image data, and an electrostatic charge formed on the photosensitive drum surface Developing units 28Y, 28M, 28 that develop latent images with toners of respective colors to form toner images
C, 28K and the respective photoconductor drums 22Y, 22M, 22C, 22K with the intermediate transfer belt 12 interposed therebetween, and electrostatically attracts the toner image formed on the photoconductor drum surface onto the intermediate transfer belt 12 Primary transfer rollers 30Y, 30M, 30C, and 30K for performing primary transfer, and cleaners 32Y, 32M, 32C, and 32K that collect and clean toner remaining on the surface of the photosensitive drum after the primary transfer are disposed. Print head unit 26Y, 26
Each of M, 26C, and 26K includes a number of LEDs arranged in a main scanning direction parallel to the axial direction of the photosensitive drum.

[0015] Cleaners 32Y, 32M, 32C, 32K
Are cleaner blades 33Y, 33M, 33C, 33K
And presses it against the surface of the photosensitive drum to scrape off the toner remaining on the surface of the photosensitive drum and collect it inside the cleaner body. The cleaner blade 33K of the cleaner 32K is pressed against the photosensitive drum with a predetermined strength by a spring 34 and is elastically supported so that the toner can be reliably scraped off. Meanwhile, cleaner blade 3
3Y, 33M, and 33C are pressed against and fixed to the photosensitive drum with an intensity higher than a predetermined intensity. Only the cleaner blade 33K is elastically supported by the spring 34 and the other cleaner 32
By reducing the size of Y, 32M, and 32C, the pitch between the image forming units can be minimized, and the size of the apparatus body is reduced. Further, the cleaner main body of the cleaner 32K is larger than the cleaner main bodies of the cleaners 32Y, 32M, and 32C, so that a larger amount of toner can be stored.

A secondary transfer roller 35 is pressed against the portion of the intermediate transfer belt 12 supported by the drive roller 18. The nip between the secondary transfer roller 35 and the intermediate transfer belt forms a secondary transfer area 36. Secondary transfer roller 3
5, a high transfer voltage is applied. The transfer voltage causes the toner image formed on the intermediate transfer belt 12 to be electrostatically attracted to the recording medium that has been conveyed to the secondary transfer area as described later so that the toner image is secondarily transferred. Has become.

A cleaner 38 is pressed against a portion of the intermediate transfer belt 12 supported by the rollers 16. This cleaner 38 is for scraping off the toner remaining on the intermediate transfer belt 12 after the secondary transfer and collecting it in the waste toner box 40.

At the lower part of the printer 10, a paper feed cassette 4 is provided.
2 are removably arranged. The sheets S stacked and stored in the sheet cassette 42 are sent out one by one from the uppermost one to the transport path 46 by the rotation of the sheet feeding roller 44.

The transport path 46 is connected to the nip portion of the timing roller pair 48, the secondary transfer area 36,
The fixing unit 50 extends to the sheet discharge tray 11 through the fixing unit 50.

In the vicinity of the timing roller pair 48, a paper feed sensor 52 is disposed. The paper feed sensor 52 detects that the leading end of the paper S sent from the paper feed cassette 42 to the transport path 46 is nipped by the timing roller pair 48. When the leading edge of the paper S is detected by the paper feed sensor 52, the timing roller pair 48 temporarily stops its rotation, and then synchronizes with the toner image on the intermediate transfer belt 12 to transfer the paper S to the secondary transfer area 36. To be sent out.

The fixing unit 50 includes a pair of rollers 56,
A fixing belt 60 supported by 58 and driven to rotate in the direction of arrow B, and a fixing roller 62 pressed against the roller 56 via the fixing belt 60 and driven to rotate in the direction of the arrow are provided. The nip portion between the fixing belt 60 and the fixing roller 62 through which the transferred paper passes forms a fixing area 64.

Next, the operation of the printer 10 having the above configuration will be described. When an image signal is input from an external device (for example, a personal computer) to an image signal processing unit (not shown) of the printer 10, the image signal processing unit converts the image signal into a yellow, cyan, magenta, and black digital image. A signal is generated, and the signal is transmitted to the LED drive circuit for the print head. This drive circuit is
Based on the input digital signal, each image forming unit 2
Printhead section 26 of 0Y, 20M, 20C, 20K
Y, 26M, 26C, and 26K emit light to perform exposure.
This exposure is performed by the print head units 26Y, 26M, 26
C and 26K are performed in order with a time difference. Thereby, each of the photosensitive drums 22Y, 22M, 22C, 2
An electrostatic latent image for each color is formed on the 2K surface.

Each of the photosensitive drums 22Y, 22M, 22C,
The electrostatic latent image formed on the image forming device 22K is stored in each of the developing devices 28Y and 28Y.
8M, 28C, and 28K are developed to form toner images of respective colors. Then, the toner images of the respective colors are primary-transferred by the respective primary transfer rollers 30 </ b> Y, 30 </ b> M, 30 </ b> C, and 30 </ b> K so as to be sequentially superimposed on the intermediate transfer belt 12 moving in the arrow A direction. After the primary transfer,
The toner of each color remaining on the surface of the photosensitive drum is supplied to the cleaner blade 3 of the cleaner 32Y, 32M, 32C or 32K.
It is scraped off by 3Y, 33M, 33C, 33K and collected inside the cleaner main body. At this time, since the cleaner blade 33K is pressed against the photoconductor drum with a predetermined strength by the spring 34, the surface of the photoconductor drum is not scraped. As a result, the life of the photosensitive drum of the frequently used black image forming unit can be extended.

The superposed toner image thus formed on the intermediate transfer belt 12 is
Reaches the secondary transfer area 36 with the movement of. In the secondary transfer area 36, the superimposed toner images of the respective colors are sent out from the paper feed cassette 42 to the transport path 46 by the action of the secondary transfer roller 35 and are collectively collected on the sheet S supplied by the timing roller pair 48. Is secondarily transcribed. The toner remaining on the intermediate transfer belt 12 after the secondary transfer is collected by the cleaner 38.

The paper S on which the toner image has been secondarily transferred is sent to the fixing unit 50 through the conveyance path 46, where it passes through the fixing area 64 where the toner image is fixed on the paper S. Then, the paper S is discharged to the paper discharge tray 11.

FIG. 2 shows a printer 10 according to another embodiment of the present invention. The printer 10 has four image forming units corresponding to each color in the direction of arrow A below the lower horizontal portion of the intermediate transfer belt 12.
Y, 20M, and 20C are arranged along the intermediate transfer belt 12 in this order. Further, the developing devices 28Y and 2
The developing unit 28K is larger than 8M and 28C, and can store a large amount of toner to be consumed.
As a result, the life of the image forming unit until the black toner frequently used runs out can be extended.

In the present embodiment, the intermediate transfer member is a belt, but may be of another shape such as a drum.

Further, in the present embodiment, a printer has been described as an example. However, the present invention can be applied to other image forming apparatuses such as a copying machine, a facsimile, and a multifunction machine of these and a printer.

[0029]

According to the image forming apparatus of the present invention, among the elements of the image forming means located at the endmost side in the arrangement direction, only the element on the side not adjacent to the image forming means is enlarged. Along with extending the life of the imaging means,
Since it is not necessary to increase the arrangement pitch, the arrangement pitch of the image forming means can be made equal and the minimum necessary pitch, and the size of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a printer according to a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a printer according to a second embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 printer 12 intermediate transfer belt (intermediate transfer member) 20Y, 20M, 20C, 20K image forming unit (image forming means) 28Y, 28M, 28C, 28K developing device (element) 32Y, 32M, 32C, 32K Cleaner (element)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yusuke Morikami 2-3-113 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Takanobu Yamada Azuchi, Chuo-ku, Osaka-shi, Osaka 2-13, Machicho, Osaka International Building Minolta Co., Ltd. F-term (reference) 2H030 AA05 AA06 AB02 AD03 BB22 BB63

Claims (4)

[Claims] 1. A rotatable intermediate transfer member, and a plurality of image forming means arranged close to each other at a predetermined pitch along the intermediate transfer member to form images of different colors on the intermediate transfer member, respectively. Wherein the image forming means has a plurality of elements in the arrangement direction along the intermediate transfer member, wherein the element of the image forming means is located at an endmost position in the arrangement direction of the image forming means. An image forming apparatus according to claim 1, wherein an element on a side not adjacent to said image forming means is enlarged. 2. The image forming apparatus according to claim 1, wherein the image forming unit having the enlarged element is an image forming unit that forms a black image. 3. The image forming apparatus according to claim 1, wherein the enlarged element is a cleaner. 4. The image forming apparatus according to claim 1, wherein the enlarged element is a developing device.