JP2007206289A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which allows a user to reduce refilling cycle of a develop agent of black toner to be consumed in a large amount, by increasing capacity of a developing agent storing section of high usage by an amount of a vacant space formed by obliquely arranging an intermediate transfer belt and differentiating a space between the intermediate transfer belt and a main body cover. <P>SOLUTION: In the image forming apparatus, two main shafts 26 and 27 over which the intermediate transfer belt 28 is trained are tilted at 30° to 70° in the rotation direction of the shaft from a horizontal state, and a first image creating unit 20a and a second image creating unit 20b are disposed vertically side by side under the intermediate transfer belt 28, and at least one of the develop agent storing sections 31a, 31b, 31c and 31d included in the image creating units 20a and 20b with large space between the image creating units and the main body cover 14, are made long in a horizontal direction to increase the capacity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a color copying machine or a printer that performs image formation by electrophotography.

In an image forming apparatus such as a color copying machine or a printer, when a user uses the image forming apparatus, if the developer has the same storage amount for all colors considered to have a difference in consumption amount, the consumption amount It is conceivable that only those with a high number of exchanges have a large number of exchanges.
In order to solve this problem and reduce the number of times a user exchanges, several techniques are conventionally known (see, for example, Patent Documents 1 to 3).
For example, in Patent Document 1, four photosensitive members, a developing device, a toner container, and the like are continuously arranged in the vertical direction below an intermediate transfer belt that is inclined and tilted 30 ° to 70 ° obliquely upward from the secondary transfer position. Are disclosed.

  Patent Document 2 discloses a color image forming apparatus in which two image forming units in which two developing devices are arranged on the periphery of an image carrier are arranged. As countermeasures against color misregistration, 1) the peripheral length of the intermediate transfer belt is an integral multiple of the photosensitive member, 2) the peripheral length of the intermediate transfer belt is an integral multiple of the intermediate transfer belt drive roller diameter, and 3) the pitch between the photosensitive members is 4) The laser beam penetrates the developing unit to expose the image carrier.

Patent Document 3 discloses that two developing units (two-station configuration) are provided on two inclined photoreceptors on an inclined surface of an intermediate transfer belt. Further, it is assumed that the developing device having the closest image moving distance from the developing unit to the secondary transfer unit is for black toner.
JP 2004-126388 A JP 2001-1000048 A JP 2003-173051 A

However, in Patent Document 1, there is a description that the toner container near the secondary transfer roller is for black toner and is longer in the horizontal direction than the others, but it does not correspond to two stations. In Patent Document 3, When the user uses the image forming apparatus, there is no mention of increasing the amount of black toner that is highly consumed.
In view of the above, the object of the present invention is to provide an intermediate transfer belt that is obliquely arranged, makes a difference in space with the main body cover, and uses a large amount of developer storage unit corresponding to the vacant space. It is an object of the present invention to provide an image forming apparatus that reduces the number of times the user replenishes a developer that is a high-consumption black toner.

  In order to solve the above problems, the invention described in claim 1 includes a developer storage unit that stores a developer, and a development unit that charges and holds the developer supplied from the developer storage unit. An image carrier that receives the developer from the developing unit and forms an image, and has two image forming units each having two or more of the developing units mounted on the image carrier. In the image forming apparatus, comprising: an intermediate transfer belt that is in contact with an image carrier and temporarily holds an image on the image carrier; and a secondary transfer unit that transfers the image from the intermediate transfer belt to a recording sheet. The two main axes that span the belt are inclined 30 ° to 70 ° in the rotational direction from the horizontal state, and the first image forming unit and the second image forming unit are installed in the vertical direction below the intermediate transfer belt. Storage of at least one developer contained in the image unit The part is installed in the horizontal direction.

According to a second aspect of the present invention, the developer storage section is for black toner.
According to a third aspect of the present invention, the vicinity of the end of the inclined intermediate transfer belt is a secondary transfer portion to the recording paper, and the intermediate transfer belt is rotated upstream in view of the secondary transfer portion. The image forming apparatus according to claim 1, wherein the closest image forming unit includes black.

According to a fourth aspect of the present invention, in the image forming unit, at least two developer storage units, two developing units, and an image carrier are integrally configured. The image forming apparatus described in the item is characterized.
According to a fifth aspect of the present invention, at least the developer storage section and the developing section are integrated, and the image according to any one of the first to third aspects is detachable from the image forming unit. Features a forming device.
According to a sixth aspect of the present invention, in the image forming unit, at least the developing unit and the image carrier are integrated, and the developer storage unit is detachable as a single unit. 4. An image forming apparatus according to any one of items 1 to 3.

  According to the present invention, when the developer is stored in the same amount for all colors, the intermediate transfer belt is disposed obliquely between the main body cover in view of the fact that only a high consumption amount is frequently replaced. It is possible to reduce the number of times the user replenishes the developer by making a difference in the space and increasing the capacity of the developer storage unit that is used in an amount corresponding to the space that is free.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a full-color laser printer as an image forming apparatus according to the present invention. First, the basic configuration will be described. Full color laser printers typically have four color developers.
Two of the four developing units 32a, 32b, 32c, and 32d are arranged on the two image carriers 22a and 22b that form images. Further, four developer storage units 31a, 31b, 31c, and 31d having different colors are set in the developing units 32a, 32b, 32c, and 32d, respectively, and the developer is set in each developing unit 32a, 32b, 32c, and 32d. To supply.

Around the image carriers 22a and 22b, charging rollers 21a and 21b for charging the surfaces of the image carriers 22a and 22b and cleaning blades 23a and 23b for cleaning the surfaces of the image carriers 22a and 22b are arranged.
There are transport coils 24a and 24b for transporting the developer scraped off by the cleaning blades 23a and 23b to a waste toner box (not shown), and the image forming units 20a and 20b are constructed as a unit. The exposure means 36a and 36b selectively irradiate to form electrostatic latent images on the image carriers 22a and 22b.
Further, the intermediate transfer belt 28 is stretched over the drive shaft 26, the sub-coaxial 27, and the primary transfer rollers 29a and 29b, and is disposed so as to be in contact with the two image carriers 22a and 22b to be attached to the image carriers 22a and 22b. The developed image is temporarily held.

Next, the image forming unit will be described. First, in an image forming unit 20a (hereinafter referred to as a first image forming unit) positioned on the upstream side in the rotation direction of the intermediate transfer belt 28 when viewed from a secondary transfer roller 39 corresponding to a transfer portion to a recording paper, first, an image is formed by a charging roller 23a. Negative charges (or positive charges) are uniformly applied to the surface of the carrier 22a.
Next, an electrostatic latent image is drawn by selectively irradiating the exposure means 36a to change the distribution of the surface potential of the image carrier 22a. This utilizes the characteristic of the image carrier 22a that the surface charge escapes at the exposed portion.
The developing unit 32b does not act on the electrostatic latent image drawn in this way, but only the developing unit 32a works. The electrostatic latent image is visualized by the color of the developer stored in the developing storage unit 31a (hereinafter, the image is visualized). Development) is performed. The developed image is primarily transferred to the intermediate transfer belt 28.

Next, in the downstream image forming unit 20b (hereinafter referred to as a second image forming unit), an image is formed in the same manner with the color of the developer stored in the developing storage unit 31c and transferred onto the intermediate transfer belt 28 first. The image is primary-transferred superimposed on the image.
The image drawn on the intermediate transfer belt 28 circulates while being held, and heads again toward the first image forming unit 20a. In the first image forming unit 20a, the developing unit 32b operates this time to perform image formation, and the image is superimposed on the circulated image. Similarly, in the second image forming unit, the images developed by the developing unit 32d are superimposed.
The full-color image formed of the four color developers formed in this way is secondarily transferred to the recording paper conveyed in time when passing through the secondary transfer roller 39, and the fixing device 39 records the image by heat. After fixing on the paper, the paper is discharged from the discharge unit 40, and a printed matter of a full color image is obtained as an output.

Next, the developer storage units 31a, 31b, 31c, and 31d, which are characteristic features of the present invention, will be described. As described above, a full color laser printer has a problem that only a specific color is consumed by a user, and the number of replacements increases for the number of printed sheets.
In order to solve this problem and reduce the number of times the user needs to replace the intermediate transfer belt 28, the intermediate transfer belt 28 is tilted by about 40 ° from the horizontal while being in contact with the secondary transfer roller 39 as shown in FIG.
When the image forming units 20a and 20b are arranged side by side below the intermediate transfer belt 28, the second image forming unit 20b disposed on the lower side of the first image forming unit 20a disposed on the upper side is illustrated. 1 A wide space can be used between the left side main body case opening / closing part 14.

That is, the developer storage units 31c and 31d included in the second image forming unit 20b can be lengthened to increase the capacity. Accordingly, by disposing a large amount of consumed colors in the developing storage units 31c and 31d included in the second image forming unit 20b, the number of sheets used until those colors need to be replaced increases. The number of times can be reduced.
Here, since black and yellow are considered as the colors with large consumption, black and then yellow are particularly desirable as the developer incorporated in the second image forming unit 20b.
Here, consider the case of outputting a monochrome image. In a monochrome image, only black is printed, and only one of the image forming units 20a or 20b including black is imaged and transferred to a recording sheet via the intermediate transfer belt 28. However, if the image travel distance from development to secondary transfer is short, the first print becomes faster.

The rotation direction of the intermediate transfer belt 28 in FIG. 1 is counterclockwise because it is determined by the paper passing direction of the recording paper, and therefore, in the upstream direction as viewed from the contact portion with the secondary transfer roller 39 used for transfer to the recording paper. The closer unit, that is, the second image forming unit 20b has a shorter image travel distance than the first image forming unit 20a.
Therefore, if black is arranged in any of the development storage units 31c and 31d included in the second image forming unit 20b, the first print at the time of monochrome printing is also accelerated, and the development storage unit 31c is set to black. Is most desirable.

The main body case opening / closing part 14 shown in FIG. The main body case opening / closing part 14 holds pressing springs 38a, 38b and pressing members 13a, 13b by pressing member holding parts 14a, 14b which are part of the main body, and the pressing member 13a is closed when the main body case opening / closing part 14 is closed. , 13b press the image forming units 20a, 20b to fix the positions.
Holes 8a, 8b, 9, and 10 are provided in the housings 12a and 12b of the image forming units 20a and 20b and the second image forming unit 20b as necessary to secure an optical path. At this time, the hole 10 opened in the developer storage units 31c and 31d in the second image forming unit 20b is opened to a minimum length that does not obstruct the optical path to the image carrier 22a. The developer can be conveyed from the vicinity of the side surfaces of 31c and 31d.

In some cases, the image forming apparatus uses a process cartridge including development units 32a, 32b, 32c, and 32d, image carriers 22a and 22b, and the like as an integral configuration. In some process cartridges, at least developer storage units 31a, 31b, 31c, and 31d, developing units 32a, 32b, 32c, and 32d, and image carriers 22a and 22b are integrated.
Further, at least the developer storage units 31a, 31b, 31c, and 31d and the developing units 32a, 32b, 32c, and 32d are integrated, and at least the developing units 32a, 32b, 32c, and 32d and the image carriers 22a and 22b are included. There is also a case where the developer storage units 31a, 31b, 31c, and 31d are integrated and can be detached as a single unit.

  Also in such an image forming apparatus, the above-described features of the present invention can be applied, the same effect can be obtained, and the life of the image carriers (photosensitive members) 22a and 22b is longer than that of the developing unit. When it is long, the effect of lowering CPP (cost per print) can be obtained by replacing only the developing unit having a short life. Furthermore, when the developing units 32a, 32b, 32c, and 32d have a long life, an effect of lowering the CPP can be obtained by replacing only the developer storage unit.

1 is a schematic view showing a full-color laser printer as an image forming apparatus according to the present invention.

Explanation of symbols

14 Body cover (body cover opening / closing part)
20a First image forming unit 20b Second image forming unit 22a Image carrier 22b Image carrier 26 shaft (intermediate transfer belt spanning shaft)
27 shaft (intermediate transfer belt spanning shaft)
28 Intermediate transfer belt 31a Developer storage unit 31b Developer storage unit 31c Developer storage unit 31d Developer storage unit 32a Development unit 32b Development unit 32c Development unit 32d Development unit 39 Secondary transfer unit (secondary transfer roller)

Claims (6)

  A developer storage section for storing the developer; a development section for charging and holding the developer supplied from the developer storage section; and an image carrier for receiving the developer from the development section and forming an image. And having two image forming units each having two or more developing units mounted on the image carrier, and in contact with each image carrier and temporarily holding an image on the image carrier In an image forming apparatus having an intermediate transfer belt for transferring and a secondary transfer portion for transferring the intermediate transfer belt to recording paper, the main two shafts that span the intermediate transfer belt are rotated from 30 ° to 70 ° from the horizontal state in the rotational direction. The first image forming unit and the second image forming unit are arranged in a vertical direction below the intermediate transfer belt, and at least one developer storage unit included in the image forming unit is installed in the horizontal direction. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the developer storage unit is for black toner.   Near the end of the inclined intermediate transfer belt is a secondary transfer portion to the recording paper, and the closest image forming unit upstream in the rotation direction of the intermediate transfer belt as viewed from the secondary transfer portion contains black. The image forming apparatus according to claim 1, wherein:   4. The image forming apparatus according to claim 1, wherein at least two developer storage units, two developing units, and an image carrier are integrated in the image forming unit. 5. .   4. The image forming apparatus according to claim 1, wherein at least the developer storage unit and the developing unit are integrated, and are detachable from the image forming unit. 5.   4. The image forming unit according to claim 1, wherein at least the developing unit and the image carrier are integrated, and the developer storage unit is detachable as a single unit. 5. The image forming apparatus according to Item.

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