JPH09134101A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the traveling stability of an intermediate transfer belt against toner staining, etc. SOLUTION: A color laser printer primarily transfers and superposes a three- primary-color-and-black-toner image successively formed on a photoreceptor 11 by a primary transfer part T1 on the intermediate transfer belt 41, and secondarily transfers the image by a secondary transfer part T2 on a sheet. The belt 41 rotates in a direction shown by an arrow (b), and a cleaner 90 is set inside. Such stain as toner on the back surface of the belt 41 is scraped by a blade 91 so as to be housed in the housing part 93 of a housing member 92. Toner is housed in a housing part 94 in the case of maintenance so as not to leak outside.

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, and more particularly to an image forming apparatus provided with an intermediate transfer belt by an electrophotographic method.

[0002]

BACKGROUND OF THE INVENTION Generally, in a full-color image forming apparatus by electrophotography, a toner image separated into three primary colors (adding black if necessary) is sequentially formed on a photosensitive drum, and an intermediate image is formed. The toner images are primarily transferred onto the transfer belt and superposed, and finally the superposed toner images are secondarily transferred onto the sheet from the intermediate transfer belt.

In the meantime, in the intermediate transfer belt, the floating toner adheres to the back surface of the intermediate transfer belt, causing a slip between the belt and the driving roller, thus deteriorating the running stability of the belt. That is, in order to stabilize the primary transfer, the driving roller of the intermediate transfer belt is usually installed on the downstream side of the primary transfer section in the belt rotation direction, and the toner floating from the primary transfer section on the downstream side. Often occurs and adheres to the back surface of the belt, causing slippage. In particular, the slip is remarkable in the configuration in which the primary transfer portion is arranged immediately above the intermediate transfer belt.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus capable of preventing a decrease in running stability of an intermediate transfer belt due to stains of toner or the like.

To achieve the above object, the image forming apparatus according to the present invention includes an intermediate transfer belt, a driving roller and a driven roller for the intermediate transfer belt, a cleaning blade press-contacted to the back surface of the intermediate transfer belt, and a holding blade for the cleaning blade. It is provided with a storage member that stores the toner dropped from the back surface of the intermediate transfer belt. Further, the intermediate transfer belt is held by a movable member that is rotatable at a position where the main body of the image forming apparatus is opened. The toner containing member is composed of a first containing portion located in the toner falling direction and a second containing portion containing the toner when the movable member is rotated to the main body open position.

In the above structure, the toner attached to the back surface of the intermediate transfer belt is scraped off by the cleaning blade and collected in the containing member. As a result, the dirt on the back surface of the intermediate transfer belt is cleaned, and the running stability is improved.
Particularly, since the cleaning blade is provided immediately after the primary transfer portion where floating toner is likely to be generated, the adhered toner does not come into contact with the driving roller, which is preferable. Further, when the movable member is rotated and the main body is opened for belt replacement or maintenance, the scraped toner is prevented from moving to the second storage portion and leaking to the outside, and the intermediate transfer is performed. It does not reattach to the belt. Moreover, since the inner side of the intermediate transfer belt is a dead space, even if the cleaning means is provided there, the size of the apparatus is not increased.

Further, it is preferable that a voltage is applied to the cleaning blade so as to maintain a potential difference between the cleaning blade and the intermediate transfer belt, which has a polarity opposite to the charging polarity of the toner.
This is for efficiently scraping off the toner.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, the present invention is applied to a full-color laser printer.

(Overall Structure of Printer) FIG. 1 shows the appearance of a full-color laser printer as seen from the front, and FIG. 2 shows its internal mechanism. In FIG. 2, the laser printer is generally shown as a photosensitive drum 1 that is rotationally driven in the direction of arrow a.
1, a laser scanning optical unit 20, a full-color developing unit 30, an intermediate transfer unit 40 having an endless intermediate transfer belt 41 that is rotationally driven in the direction of arrow b, and a paper feed unit 60. It is composed of.

A charging brush 12 and a cleaner 13 are further installed in the photoreceptor unit 10, and a back portion of the cleaner 13 is a waste toner storage chamber 14. Charging brush 1
2 uniformly charges the surface of the photoconductor drum 11 to a predetermined potential. The cleaner 13 scrapes off the toner remaining on the photosensitive drum 11 by the blade 13a.

The laser scanning optical unit 20 is a well-known one having a laser diode, a polygon mirror and an fθ optical element built-in, and its control section has C (cyan), M (magenta), Y (yellow) and Bk (black). The print data for each is transferred from the host computer. The laser scanning optical unit 20 sequentially outputs print data for each color as a laser beam, and scans and exposes the photosensitive drum 11. As a result, an electrostatic latent image for each color is sequentially formed on the photosensitive drum 11.

The full color developing unit 30 includes C, M,
Four color developing devices 31C, 31M, 31Y, 31Bk containing developers containing Y and Bk toners are integrated, and can be rotated clockwise by one step with the support shaft 33 as a fulcrum. . Each developing device includes a photoconductor drum 11
Each time an electrostatic latent image of each color is formed, the developing sleeve 32 of the corresponding developing device is rotated and switched so as to be located at the developing position facing the photoconductor drum 11.

In the intermediate transfer unit 40, the intermediate transfer belt 41 is endlessly stretched over the drive roller 42, the support roller 43, and the tension rollers 44 and 45, and in the direction of arrow b in synchronization with the photosensitive drum 11. It is driven to rotate. A projection (not shown) is provided on a side portion of the intermediate transfer belt 41. The microswitch 49 detects the projection, thereby controlling image forming processes such as exposure, development, and transfer. The intermediate transfer belt 41 is pressed by the rotatable primary transfer roller 46 and comes into contact with the photosensitive drum 11, and this contact portion is the primary transfer portion T ₁ . In addition, the intermediate transfer belt 41
Is exposed to the horizontal conveyance path 65 of the recording sheet at the portion supported by the support roller 43, and is in contact with the rotatable secondary transfer roller 59. This contact portion is the secondary transfer portion T ₂ .

Inside the intermediate transfer belt 41, a cleaner 90 for adhering toner is installed. Cleaner 90
Is composed of a cleaning blade 91 made of an elastic material that comes into pressure contact with the back surface of the intermediate transfer belt 41, and a storage member 92 that holds the blade 91 and stores the toner scraped off from the back surface of the belt 41. The blade 91 constantly presses against the back surface of the intermediate transfer belt 41 to scrape off the toner and dust adhering to the back surface of the belt 41. The blade 91 is provided between the primary transfer portion T ₁ and the drive roller 42,
In other words, on the downstream side of the primary transfer portion T _{1 in} the belt running direction,
It is pressed against the back surface of the belt 41. The downstream side is a place where the floating toner generated in the primary transfer portion T ₁ easily adheres to the back surface of the belt 41. By installing the blade 91 at this location, it is possible to reliably prevent the adhered toner from reaching the drive roller 42, and to prevent the belt 41 from slipping or the like.
Eliminating the factors that deteriorate the running stability of.

Further, another cleaner 50 is installed in the intermediate transfer unit 40. The cleaner 50 has a blade 51 for scraping residual toner on the intermediate transfer belt 41. This blade 51 and the above 2
The next transfer roller 59 can be brought into contact with or separated from the intermediate transfer belt 41 at a predetermined timing.

The paper supply section 60 includes a paper supply tray 61 that can be opened to the front side (the side where the operator is normally located) of the printer main body 1, a paper supply roller 62, and a timing roller 63. The recording sheets S are stacked on the paper feed tray 61, and are fed one by one to the right in FIG. 2 by the rotation of the paper feed roller 62, and are synchronized with the image formed on the intermediate transfer belt 41 by the timing roller 63. Then, it is sent to the secondary transfer portion T ₂ . The horizontal conveyance path 65 for the recording sheet is composed of an air suction belt 66 or the like, and the recording sheet is ejected from the fixing device 70 to the upper surface of the printer body 1 through conveying rollers 76, 77, 78.

(Full Color Printing Operation) Here, an outline of the full color printing operation in this embodiment will be described. At the start of the printing operation, the secondary transfer roller 59 and the cleaning blade 51 are separated from the intermediate transfer belt 41. When the printing operation is started, the photosensitive drum 11 is driven to rotate at the same circumferential speed in the direction of arrow a and the intermediate transfer belt 41 in the direction of arrow b, and the photosensitive drum 11 is charged to a predetermined potential by the charging brush 12. .

Subsequently, the laser scanning optical unit 20 exposes the cyan image, and an electrostatic latent image of the cyan image is formed on the photosensitive drum 11. This electrostatic latent image is immediately developed by the developing device 31C, and the toner image becomes 1
The image is transferred onto the intermediate transfer belt 41 at the next transfer portion T ₁ . 1
Immediately after the completion of the next transfer, the developing device 31M is switched to the developing position, and subsequently, exposure, development and primary transfer of the magenta image are performed. Thereafter, similarly, switching to the developing device 31Y, exposure, development, and primary transfer of the yellow image are performed. Further, switching to the developing device 31Bk, exposure of black image, development,
The next transfer is performed, and the toner image is superimposed on the intermediate transfer belt 41 for each primary transfer.

When the final primary transfer is completed, the developing unit 30 is switched to the developing device 31C for the next printing process, and at the same time, the secondary transfer roller 59 and the cleaning blade 51 are pressed against the intermediate transfer belt 41. At this time, the recording sheet S is sent to the secondary transfer portion T ₂ , and the full-color toner image formed on the intermediate transfer belt 41 is transferred onto the recording sheet S. When this secondary transfer is completed, the secondary transfer roller 59 and the cleaning blade 51
Is separated from the intermediate transfer belt 41.

(Opening and Closing of Printer Body) Printer Body 1
Is divided into a fixed side frame 2 and a movable side frame 5 as shown in FIG. The movable frame 5 is rotatable about a support shaft 81, and the main body 1 can be opened by rotating the movable frame 5 to the front side. A cover 6 is installed on the movable frame 5, and the cover 6 constitutes a surface shell.

The stationary scanning frame 2 is provided with a laser scanning optical unit 20, a developing unit 30, a paper feeding section 60, a horizontal conveying path 65, a fixing device 70 and the like. The movable side frame 5 includes a photoconductor unit 10 and an intermediate transfer unit 4
0 is set. When the movable frame 5 is opened,
The main body 1 includes a developing unit 30, a paper feeding unit 60, and a horizontal transport path 6.
5 is opened almost entirely so as to be accessible from the outside.
In this open state, the photoconductor unit 10 and the intermediate transfer unit 40 are attachable to and detachable from the movable frame 5, and the developing devices 31 are also attachable to and detachable from the developing unit 30.

Further, the paper feeding section 60 and the horizontal transport path 65 are completely opened, so that the paper jam removal processing is facilitated, and the maintenance such as inspection and replacement of the secondary transfer roller 59 is also facilitated.

(Unit Attachment / Detachment / Positioning Mechanism) Next,
The attachment / detachment / positioning mechanism of each unit 10, 40 will be described. Photoconductor unit 10 and intermediate transfer unit 40
Is attachable to and detachable from the movable frame 5, and when the movable frame 5 is closed, it must be set at a predetermined position in the main body 1. Therefore, as shown in FIG. 4, in the photoconductor unit 10, both ends of the support shaft 11a of the photoconductor drum 11 are projected outward, and in the intermediate transfer unit 40, both ends of the support shaft 43a of the support roller 43 are placed outside. I made it stick out. In the movable frame 5, both ends of the support shaft 82 are projected outward. On the other hand, positioning plates 85 were fixed to the inner sides of both sides of the fixed frame 2, and the positioning plates 85 were formed with grooves 85a, 85b, 85c. When the movable frame 5 is closed, the support shafts 11a, 43a,
Both ends of 82 are groove portions 85a, 85b, 85c.
, And finally each support shaft 11a, 43a, 82 abuts the inner part of the groove 85a, 85b, 85c,
Each member is positioned and fixed at a predetermined position.

In FIG. 4, pins 15 project from both sides of the photoconductor unit 10, and support shafts 42a and 44a project from both sides of the intermediate transfer unit 40. Positioning plates 86 are fixed to the inside of both sides of the movable frame 5,
Grooves 86a and 86b are formed in the positioning plate 86. In the intermediate transfer unit 40, the support shafts 42a and 44a are engaged with the groove portion 86a, so that the photoconductor unit 10
The pins 15 are attached to the movable-side frame 5 by engaging the pins 15 with the groove portions 86b.

On the other hand, the positioning plate 86 has a lever 87,
88 are rotatably mounted on pins 87a and 88a, respectively, and the levers 87 and 88 are urged clockwise by a torsion spring 89. The mounting on the movable frame 5 is performed from the intermediate transfer unit 40. When the support shafts 42a and 44a are moved along the groove portion 86a and the unit 40 is moved downward, the lever 87 slightly escapes in the counterclockwise direction, and the support shaft 4 is supported by the spring force of the torsion spring 89.
2a and 44a are pressed. The unit 40 is positioned and fixed to the movable frame 5 by the support shaft 42a coming into contact with the inner portion of the groove 86a. In addition, the pin 15 and the groove 8
When the photoconductor unit 10 is moved downward along 6b, the lever 88 slightly escapes in the counterclockwise direction, and the pin 15 is pressed by the spring force of the torsion spring 89. Bottom pin 1
The unit 10 is positioned and fixed to the movable-side frame 5 by bringing the unit 5 into contact with the inner portion of the groove 86b.

(Operation of Belt Backside Cleaner) By the way,
The cleaner 90 scrapes off dirt such as toner adhering to the back surface of the intermediate transfer belt 41 during a printing operation, and stores it in a storage member 92. In the present embodiment, since the primary transfer portion T ₁ is arranged above the intermediate transfer belt 41, or the primary transfer portion T ₁ is located above the secondary transfer portion T ₂ , the intermediate Toner adheres to the back surface of the transfer belt 41 in a relatively large amount. The amount of toner adhered to the back surface of the intermediate transfer belt 41 is larger in the primary transfer portion T ₁ than in the secondary transfer portion T ₂ . Therefore, the cleaner 90
The effect of providing the sheet between the primary transfer portion T ₁ and the driving roller 42 is remarkable.

Further, in the housing member 92 (see FIG. 2), the bottom portion 92a and the side portion 92b constitute the first housing portion 93, and the bottom portion 92a, the side portion 92c and the upper portion 92d constitute the second housing portion 94. doing. Usually, the scraped off toner is stored in the first storage portion 93. On the other hand, as described above, when the movable frame 5 is rotated and the main body 1 is opened, the intermediate transfer unit 40 stands up as shown in FIG. At this time, the toner does not move from the first storage portion 93 to the second storage portion 94, leak to the outside, or reattach to the back surface of the intermediate transfer belt 41.

A voltage having a polarity opposite to the charging polarity of the toner is applied to the cleaning blade 91.
This voltage value is adjusted so that the blade 91 and the belt 41 have a potential difference of a polarity opposite to the charging polarity of the toner. As a result, the scraping of the toner from the belt 41 by the blade 91 is efficiently performed.

(Modification of Storage Member) FIG. 6 shows a cleaner 9
An example in which the shape of the toner storage member 92 of 0 is slightly changed is shown. This housing member 92 is provided with a step at the corner to divide the first housing portion 93 and the second housing portion 94.

(Other Embodiments) The image forming apparatus according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention. In particular, the configuration of the cleaner 90 is arbitrary. The present invention can also be applied to a full-color copying machine equipped with a document image reading means.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a full-color laser printer according to an embodiment of the present invention.

FIG. 2 is an internal structural view of the printer, in which a movable frame is closed.

FIG. 3 is an internal structural view of the printer, in which a movable frame is opened.

FIG. 4 is an explanatory view showing a state in which a photoconductor unit, an intermediate transfer unit, and a developing device are taken out from the printer.

FIG. 5 is an explanatory diagram showing a state in which the movable side frame is opened and the intermediate transfer unit is erected in the printer.

FIG. 6 is a schematic cross-sectional view showing a modified example of the back surface cleaner of the intermediate transfer belt.

[Explanation of symbols]

5 ... Movable side frame 11 ... Photosensitive drum 40 ... Intermediate transfer unit 41 ... Intermediate transfer belt 42 ... Driving roller 43 ... Support roller 90 ... Cleaner 91 ... Cleaning blade 92 ... Housing member 93 ... First housing portion 94 ... Second housing Part T ₁ ... Primary transfer part T ₂ ... Secondary transfer part

Claims (2)

[Claims] 1. A toner image formed on an electrostatic latent image carrier is primarily transferred onto an intermediate transfer belt, and the toner image is transferred onto the intermediate transfer belt.
An image forming apparatus for secondarily transferring a next-transferred toner image onto a sheet has the following structure: a driving roller and a driven roller for rotationally driving the intermediate transfer belt; a movable member for holding the intermediate transfer belt; The movable member is rotatable to a position where the main body of the image forming apparatus is opened; a cleaning blade that presses against the back surface of the intermediate transfer belt between the primary transfer portion and the drive roller; holds the cleaning blade, and An accommodating member for accommodating the toner scraped off from the back surface of the intermediate transfer belt, the accommodating member being a first accommodating portion positioned in the toner falling direction, and the toner when the movable member is rotated to the main body open position. And a second accommodating portion for accommodating the image; an image forming apparatus. 2. The image forming according to claim 1, wherein a voltage is applied to the cleaning blade so as to have a potential difference of a polarity opposite to a charging polarity of toner between the cleaning blade and the intermediate transfer belt. apparatus.