JPH1138774A - Transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the bias to a transfer medium and invariably secure a good transfer property by arranging transfer medium cleaning means cleaning the back face side of the transfer medium on the upstream side of a transfer means, and cleaning the back face of the transfer medium immediately before the transfer medium is brought into contact with the transfer means. SOLUTION: Belt cleaning brushes 270 are arranged on the inside of a transfer belt 216 on the upstream side of the positions where transfer input rollers 251 are arranged on the back face of photoreceptor drums 222 and the transfer belt 216 (transfer area). The brush section of each belt cleaning brush 270 is set slightly longer than the shaft of the transfer belt 216 in the longitudinal direction of a rotary shaft, and it is rotated clockwise or counter clockwise direction centering on the brush rotation support shaft 272 of a brush fitting holder 271. A load is normally applied CW by a twist spring, and the belt cleaning brushes 270 are arranged in parallel with the transfer belt 2 16 and clean its back face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device for transferring an image formed on an image carrier to a transfer material.

[0002]

2. Description of the Related Art In a color image forming apparatus, for example, a color digital copying machine, a color image is output from a printer after a predetermined image processing is performed on an image of a document input from a scanner.

For example, Japanese Patent Publication No. 1-45632 discloses that an image of a color original is color-separated and read by a color CCD, and the read color-separated image of the color original is stored in a memory and then sequentially read out. A color image forming apparatus that reproduces a color image in a recording unit is described.

In the color image forming apparatus described in this publication, a color separation image of a color original read by a color CCD is temporarily stored in a buffer memory of each color, and then sequentially stored in the buffer memory. The information is read, and a toner image of each color is reproduced on the photoreceptor by the semiconductor laser based on the color separation image information.

Then, a color image is reproduced by finally superimposing toner images of each color on the transfer material surface on the transfer drum.

However, in this method, since a single color image is reproduced by superimposing a single color image a plurality of times on a transfer material (paper) supported on a transfer drum, one color image is output. In such a case, there is a problem that it takes too much time.

Therefore, recently, a color recording apparatus of a process in which a plurality of recording units for recording each single color image are arranged in parallel is described in Japanese Patent Laid-Open No. 4-341873.

According to this method, a recording unit is arranged for each image data of each color, and the recording units arranged in parallel are controlled so that the images are sequentially recorded in accordance with the conveyance of the sheet. Recording is possible.

There are various methods for transferring the toner images of each color formed on the photoreceptor in each recording unit onto a transfer material.

Conventionally, if the transfer method using a corona discharge wire is the most general method, there has been a problem in commercialization recently due to environmental problems such as generation of ozone, or downsizing of the entire apparatus. .

Therefore, as described in the above-mentioned publication, a method using a transfer roller is adopted, and an image is transferred from the transfer roller in a state where a predetermined bias is applied from the back side of the transfer belt. The image on the photoreceptor is transferred onto the transfer material by being pressed against the formed photoreceptor.

[0012]

However, in this roller transfer method, foreign matters such as dust and toner adhered to the front surface of the transfer roller or the back surface of the transfer belt affect the transfer efficiency, or cause the transfer material to undulate. Vibration, uneven transfer of the transfer material, and the like may be affected, and this is a major problem in the color process in which toner images of each color are sequentially superimposed on the transfer material with high accuracy, which appears in image quality and the like.

Japanese Patent Application Laid-Open No. 1-177578 discloses a cleaning device for cleaning the surface of a transfer belt supporting roller that supports a transfer belt in a stretched state. However, the surface of the supporting roller is originally stained directly. However, there is a possibility that the foreign matter that has once adhered to the back surface of the transfer belt adheres to the support roller during rotational driving, and the same problem as described above may occur.

Therefore, in the present invention, in a roller transfer method using a transfer roller employed in a color recording process such as tandem recording, a cleaning means for cleaning the back surface of the transfer belt is provided, and in a limited arrangement space. An object of the present invention is to prevent the back surface of the transfer belt and the surface of the transfer roller rotating constantly in contact with the back surface of the transfer belt from being stained.

It is another object of the present invention to clean the transfer belt downstream of the position where foreign matter is most likely to adhere and upstream of the transfer means, or upstream of a support roller supporting the transfer belt. And

[0016]

According to a first aspect of the present invention, there is provided a transfer device for transferring an image formed on an image carrier onto a transfer material. A transfer medium that is stretched between two support rollers and that is disposed close to the transfer area of the image carrier; and a transfer that presses the transfer medium from the back side of the transfer medium toward the transfer area of the image carrier. Means, on the upstream side of the transfer movement direction of the transfer medium, before the transfer medium is guided to a portion where the transfer medium presses the transfer medium against the transfer region of the image carrier, the back side of the transfer medium. Cleaning means for cleaning the rear surface of the transfer medium by acting on the transfer medium.

According to a second aspect of the present invention, in the transfer device, the cleaning operation efficiency is set to be greater at the vicinity of both ends in the direction perpendicular to the direction of transport of the transfer medium than at the center.

According to a third aspect of the present invention, in the transfer device, the cleaning unit is provided at a portion where the transfer unit presses the transfer medium against a transfer area of the image carrier on an upstream side in a conveying movement direction of the transfer medium. Before the transfer medium is guided, a first cleaning position that acts on the back surface of the transfer medium to clean the back surface of the transfer medium, and a second cleaning position that acts on the surface of the transfer means to clean the transfer means. It is provided so that it can move between.

According to a fourth aspect of the present invention, there is provided a transfer device for transferring an image formed on an image carrier to a transfer material, wherein the image carrier is stretched between at least two support rollers. A transfer medium disposed in the vicinity of the transfer area, a transfer unit that presses the transfer medium from the back side of the transfer medium toward the transfer area of the image carrier, and an upstream side in the moving and conveying direction of the transfer medium. Before the transfer medium is guided to a portion where the support roller that stretches and supports the transfer medium acts on the transfer medium, a transfer medium cleaning unit that acts on the back side of the transfer medium to clean the back surface of the transfer medium is provided. ing.

According to a fifth aspect of the present invention, there is provided a transfer device for transferring an image formed on an image carrier to a transfer material, wherein the image carrier is stretched between at least two support rollers. And a first position for pressing the transfer medium from the back side of the transfer medium toward the transfer area of the image carrier, and pressing the transfer medium against the image carrier. A transfer means movable between a second position retracted from the back surface of the transfer medium by releasing the transfer means, and a transfer means positioned upstream of the transfer means in the transporting direction of the transfer means, and
Cleaning means for contacting the transfer means and the back surface of the transfer medium which has been released by pressing the image carrier due to the movement of the transfer means and cleaning the transfer means and the back surface of the transfer medium. And

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital color copying machine which is an embodiment of the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a configuration of a digital color copying machine.

A document table 111 and an operation panel are provided on the upper surface of the copying machine body 1.
An automatic document feeder 112 is mounted on the upper surface of the document table 111 so as to be openable and closable with respect to the document table 111, and has a predetermined positional relationship with respect to the surface of the document table 111. further,
An image reading unit 110 and an image forming unit 210 are configured inside the copying machine main body 1.

First, an automatic document feeder 112 mounted on a document table 111 on the upper surface of the copying machine main body 1 is a double-sided automatic document feeder 112 corresponding to a double-sided document.
Document A is conveyed so that one side of document A faces at a predetermined position on platen 111, and after image reading on one side is completed, the other side is placed on platen 111.
The document A is inverted so as to face the predetermined position, and is conveyed toward the document table 111.

After the reading of one side of the original has been completed, the original is discharged, and a double-sided conveying operation is performed for the next original. The operation of transporting the document A and reversing the front and back sides is controlled in relation to the operation of the entire copying machine.

In order to read the image of the original A conveyed onto the original platen 111 by the automatic double-sided automatic document feeder 112, the original is moved back and forth in parallel along the lower surface of the original platen 111 below the original platen 111. The original scanning body is arranged.

This original scanning body is provided with a predetermined distance on the lower surface of an original table 111 comprising an exposure lamp for exposing the original image surface and a first mirror for deflecting a reflected light image from the original in a predetermined direction. A first scanning unit 113 that reciprocates in parallel at a scanning speed of, and a second and second unit that further deflects a reflected light image from a document deflected by a first mirror of the first scanning unit 113 in a predetermined direction. 3
The second scanning unit 11 reciprocates in parallel with the first scanning unit 113 composed of a mirror with a constant speed relationship.
4, an optical lens 115 for reducing the reflected light image from the document deflected by the third mirror of the second scanning unit to form an optical image at a predetermined position, and an optical image reduced by the optical lens 115 And a photoelectric conversion element 116 that sequentially photoelectrically converts the light image and outputs a reflected light image from the document as an electric signal.

The document image information converted into an electric signal by the photoelectric conversion element 116 is further transferred to an image processing unit described later and subjected to predetermined processing as image data.

Next, the image forming section 210 located on the lower side of the copying machine main body 1 will be described. A sheet feeding mechanism 211 is provided below the image forming unit 210 shown in FIG. 1, and separates the sheets stacked and accommodated in the sheet tray one by one and supplies the sheets toward the recording unit.

The paper separated and supplied one by one is
The sheet is controlled and conveyed by a pair of registration rollers 212 disposed in front of the image forming unit 210, and is reconveyed and conveyed at a timing with the image forming unit 210.

Below the image forming section 210, a transfer / transport belt mechanism 213 extending substantially in parallel is arranged. The transfer / transport belt mechanism 213 extends between a plurality of rollers such as a driving roller 214 and a driven roller 215. The paper is configured to be electrostatically attracted and conveyed.

Further, a fixing device 217 for fixing the toner image transferred and formed on the sheet onto the sheet is disposed downstream of the transfer / conveying belt mechanism 213. Is passed through the conveyance direction switching gate 218 and the discharge roller 219.
Paper discharge tray 220 attached to the outer wall of the apparatus
Is discharged on top.

The conveyance direction switching gate 218 discharges the sheet after fixing to the outside of the apparatus, or returns to the image forming section 21 again.
0, or selectively switches the transport path of the sheet.
The paper whose transport direction has been switched again toward the image forming unit 210 by the switch 18 is transferred to the switchback transport path 221.
, Is supplied again to the image forming unit 210.

The driving roller 214 and the driven roller 21
5 and the like, the transfer conveyance belt 216 stretched substantially in parallel.
The first, second, third, and fourth image forming stations Pa, Pb, PC, and Pd are arranged side by side in the order from the upstream side of the transport path near the transfer transport belt 216.

The transfer conveyance belt 216 is frictionally driven by the drive roller 214 in the direction indicated by the arrow Z in FIG. 1, and carries the transfer material P fed through the paper feeding mechanism 211 as described above. Then, the sheet P is sequentially conveyed to the above-described image forming stations Pa, Pb, Pc, and Pd.

Each image forming station Pa, Pb, P
c and Pd have substantially the same structure, and are driven to rotate in the direction of arrow F shown in FIG.
b, 222c, 222d, each photosensitive drum 222
, Chargers 223a, 223b, 223c, 223d for uniformly charging the photosensitive drum 222, and developing devices 224a, 224b, 224c for developing the electrostatic latent image formed on the photosensitive drum 222. 224d and a transfer discharger 225 for transferring the developed toner image to the transfer material P
a, 225b, 225c, 225d and the photosensitive drum 2
Cleaning means 2 for removing toner remaining on surface 22
26a, 226b, 226c, 226d are sequentially arranged along the rotation direction of the photosensitive drum 222.

Each photosensitive drum 222a, 222
Above b, 222c and 222d, a semiconductor laser device that emits dot light modulated in accordance with image data, a deflecting device for deflecting light from the semiconductor laser device in the main scanning direction, and a deflecting device A laser beam scanner unit 22 including an fθ lens and the like for forming the focused laser beam on the surface of the photosensitive drum 222.
7a, 227b, 227c, and 227d are provided, respectively.

The laser beam scanner unit 227a receives a pixel signal corresponding to the yellow component image of the color original image, the laser beam scanner unit 227b receives a pixel signal corresponding to the magenta component image of the color original image, and the laser beam scanner unit 227c. Is input with a pixel signal corresponding to a cyan component image of a color original image, and a laser beam scanner unit 227d is input with a pixel signal corresponding to a black component image of a color original image.

Thus, the photosensitive drum 22 of each recording unit
2, an electrostatic latent image corresponding to the color-converted original image information is formed, and yellow toner, magenta toner, and developing device 227c of each recording unit are used for the developing device 227a. Contains the cyan toner and the developing device 227d contains the black toner, so that the document image information that has been color-converted in each recording unit is reproduced as a toner image of each color.

A paper-suction (brush) charger 228 is provided between the first image forming station Pa and the paper feeding mechanism 211. And the sheet feeding mechanism 211
Is transported from the first image forming station Pa to the fourth image forming station Pd in a state where the transfer material P supplied from the printer is securely attracted onto the transfer transport belt 216.

On the other hand, a static eliminator (not shown) is provided almost directly above the driving roller 214 between the fourth image forming station Pd and the fixing device 217. An alternating current for separating the transfer material P electrostatically attracted to 216 is applied.

In the above-described color copying machine, a cut sheet is used as the transfer material P, and the transfer material P is sent out from the paper feed cassette and supplied into the guide of the paper feed path of the paper feed mechanism 211. Then, the leading end portion of the transfer material P is detected by the sensor (not shown), and the sheet is temporarily stopped by the registration roller pair 212 according to a detection signal output from this sensor. Then, the sheet is sent to the transfer / conveying belt 216 rotating in the direction of arrow Z in FIG. 1 at the timing of each of the image forming stations Pa, Pb, Pc, and Pd.

At this time, the suction charger 228 described above is used.
The transfer / conveying belt 216 is charged at a predetermined rate by the image forming stations Pa, Pb, Pc, P
During the passage through d, the paper is stably transported and supplied.

Each image forming station Pa, Pb, P
In c and Pd, toner images of each color are formed by the above-described configuration, respectively, and are superimposed on the support surface of the transfer material P which is electrostatically attracted and conveyed by the transfer / conveyance belt 216.
When the transfer of the image by the fourth image forming station Pd is completed, the sheet is separated from the transfer conveyance belt 216 by the discharging device from the leading end of the sheet and guided to the fixing device 217. And the transfer material P on which the toner image is finally fixed.
Is discharged from the transfer material discharge port onto the discharge tray 220.

(Circuit Description of Image Processing Unit) Next, the configuration and functions of a color image information image processing unit mounted on a color digital copying machine will be described.

FIG. 2 is a block diagram of the image processing section included in the color digital copying machine. The image processing unit 210 included in the digital color copying machine includes an image data input unit 40, an image processing unit 41, and an image data output unit 4.
2, an image memory 43 including a hard disk device or a RAM (random access memory), a central processing unit (CPU) 44, an image editing unit 45, and an external interface unit 46.

An image data input unit 40 is a three-line color CCD 40a capable of reading a color original image and outputting line data obtained by color separation into RGB color components.
A shading correction circuit 40 for correcting the line image level of the line data read by the color CCD 40a
b, a line aligning unit 40c such as a line buffer for correcting a deviation of image line data read by the three-line color CCD 40a, and a three-line color CCD 40a
A sensor color correction unit 40d that corrects the color data of the line data of each color output from the MTF unit 40e that corrects the change in the signal of each pixel so as to have a sharp edge, It comprises a gamma correction unit 40f that performs sensitivity correction.

The image processing section 41 includes an image data input section 40
Alternatively, a color space correction circuit 41a for correcting a color reproduction range of a color image signal input via an interface to be described later to a color reproduction range of color toner in the recording apparatus.
A masking circuit 41b for converting the RGB signals of the input image data into YMC signals corresponding to the respective printing units of the printing apparatus; a black signal from the RGB signals of the color image input via the image data input unit 40 or an interface to be described later; An under-color removal / black addition circuit (UCR.) That performs a black addition process of adding a black component signal output from the black detection circuit 41c based on the YMC signal output from the black detection circuit 41c and the masking circuit 41b for detecting components. BP) 41
d, a density processing circuit 41e for adjusting the density of the color image signal based on the density conversion table, a scaling processing circuit 41f for scaling the input image information based on the set magnification, and an image from the input image data. A separation / screen circuit 41 for detecting character / photo / halftone areas in information to separate areas and determining an image output pattern
g.

The image data output section 42 performs a laser control unit 42a for performing pulse width modulation based on image data of each color, and a laser based on a pulse width modulation signal corresponding to an image signal of each color output from the laser control unit 42a. It comprises laser scanner units 42b, 42c, 42d, 42e of each color for recording.

The image memory 43 sequentially receives the 8-bit 4-color (32-bit) image data output from the image processing section 41 and temporarily stores the 8-bit 4-color (32-bit) image data from the 32-bit data into 8-bit 4-color image data. A hard disk control unit 43a for converting and outputting the divided data to four hard disks, and for storing and managing image data of 8 bits and 4 colors as image data for each color.
Base hard disks (rotary storage media) 43b, 43c,
43d and 43e.

The central processing unit (CPU) 44 includes an image data input section 40, an image processing section 41, an image data output section 42, an image memory 43, and an image editing section 4 described later.
5, and controls the external interface unit 46 based on a predetermined sequence.

The image editing unit 45 performs a predetermined image editing on the image data once stored in the image memory 43 via the image data input unit 40, the image processing unit 41, or an interface described later. It is.

Further, the interface 46 is a communication interface means for receiving image data from an external image input processing device provided separately from the digital copying machine.

The image data input from the interface 46 is also converted into a data level that can be handled by the image recording unit 210 of the digital copying machine by temporarily inputting the image data into the image processing unit 41 and performing color space correction and the like. Then, the data is stored and managed in the hard disks 43b, 43c, 43d, and 43e.

(Explanation of the control structure of the entire digital copying machine)
FIG. 3 is a diagram showing a state in which the operation of each unit of the entire digital copying machine is managed by a central processing unit (CPU) 44.

The image data input unit 40, the image processing unit 41,
The image data output unit 42, the image memory 43, and the central processing unit (CPU) 44 are the same as those in FIG.

The central processing unit 44 has the RADF2-
1. Each of the drive mechanisms constituting the digital copying machine, such as the scanner unit 2, the laser printer unit 3, and the like, is managed by sequence control, and a control signal is output to each unit.

Further, an operation board unit 47 composed of an operation panel is connected to the central processing unit 44 in a mutually communicable state. The control signal is transmitted to the central processing unit 44 in accordance with the copy mode set and inputted by the operator. To operate the digital copying machine according to the mode.

A control signal indicating the operating state of the digital copier is transferred from the central processing unit 44 to the operation board unit 47, and the operation board unit 47 side determines the current state of the apparatus by the control signal. The operation state is displayed on a display unit or the like as shown to the operator as to whether there is.

Reference numeral 46 denotes image information as described in FIG.
And an image data communication unit provided to enable information communication with other digital imaging devices such as image control signals.

(Explanation of Operation Panel) FIG. 4 shows an operation panel in a color digital copying machine.

A touch panel liquid crystal display device 6 is arranged at the center of the operation panel, and various mode setting keys are arranged around the touch panel liquid crystal display device 6.

On the screen of the touch panel liquid crystal display device 6, there is a screen switching instruction area for constantly switching to a screen for selecting an image editing function, and by directly pressing this area with a finger, various image editing functions are selected. A list of various editing functions is displayed on the liquid crystal screen so that it can be performed.

From among the displayed various editing functions, the editing function is set by the operator touching the area where the desired function is displayed with the finger.

The group of various setting keys arranged on the operation panel will be briefly described. Reference numeral 7 denotes a dial for adjusting the brightness of the screen of the liquid crystal display device 6. 8 is a magnification automatic setting key for setting a mote for automatically selecting a magnification,
Reference numeral 9 denotes a zoom key for setting a copy magnification in increments of 1%, reference numerals 10 and 11 denote fixed magnification keys for reading out and selecting a fixed magnification, and reference numeral 12 denotes an equal-magnification key for returning the copy magnification to a standard magnification (actual magnification). It is.

Reference numeral 13 denotes a density switching key for switching the copy density adjustment from automatic to manual or to the photo mode, 14 denotes a density adjustment key for finely setting the density level in the manual mode or the photo mode, and 15 denotes a copying machine. Is a tray selection key for selecting a desired paper size from among the paper sizes set in the paper supply unit.

Reference numeral 16 denotes a copy number setting key for setting the number of copies, 17 a clear key for clearing the number of copies or operating when stopping continuous copying, 18 a start key for instructing the start of copying, Reference numeral 19 denotes an all-release key for releasing all of the currently set modes and returning to the normal state, reference numeral 20 denotes an interrupt key operated when a copy of another document is desired during continuous copying, and reference numeral 21
Is an operation guide key for displaying a message on the operation method of the copier by operating when the operation of the copier is unknown, and 22 is a message forward for displaying the continuation of the message displayed by operating the operation guide key 21 Is the key.

Reference numeral 23 denotes a double-sided mode setting key for setting a double-sided copying mode, and reference numeral 24 denotes a post-processing mode setting key for setting an operation mode of a post-processing apparatus for sorting copies discharged from a copying machine. .

Reference numerals 25 to 27 denote setting keys for a printer mode and a facsimile mode. Reference numeral 25 denotes a memory transmission mode key for temporarily storing transmission originals in a memory and then transmitting them. Reference numeral 26 denotes a copy and fax mode for the digital copying machine. A copy / fax / printer mode switching key 27 for switching between the telephone numbers is a one-touch dial key for storing a destination telephone number in advance and transmitting a telephone call to the destination by one-touch operation during transmission.

The operation panel presented this time and the various keys arranged on the operation panel are just one embodiment, and the keys provided on the operation panel differ depending on various functions mounted on the color digital copying machine. Needless to say.

(Explanation of Transfer Conveying Unit) Next, the characteristic portion of the image forming apparatus of the present invention will be described. FIG. 5 is a schematic configuration diagram near the transfer / conveyance unit during color image formation.

A voltage (1.0 to 3.0 kV) is applied to the shaft of the support roller 215 on the upstream side of the support rollers 214 and 215 which stretches the transfer belt 216, and the transfer belt 216 is applied to this shaft. The conductive roller 250 is grounded via a non-linear element or a resistor as a means for applying electric charge to the recording paper P via a line (not shown).

The recording paper P fed from the paper feeding mechanism 211 enters between the conductive roller 250 and the transfer belt 216 and charges are injected into the recording paper P by the conductive roller 250. The transfer belt 216 is conveyed in a state in which an attraction force is generated and electrostatically attracted.

Thereafter, the recording paper P is transferred to the photosensitive drum 222
a, 222b, 222c, 222d and transfer belt 216
Into the nip formed by the transfer belt 216 and the transfer input roller (bias roller) 251a,
A transfer electric field is applied by 251b, 251c, and 251d, and a toner image is transferred onto the recording paper P.

Thereafter, the recording paper P on which the image has been transferred is conveyed to the fixing unit 217 while being attracted to the transfer belt 216, and the image is fixed on the recording paper P.

Here, the transfer nip between the photosensitive drum 222 and the transfer belt 216 will be described in more detail. The transfer nip portion is located upstream of the position where the transfer input roller 251 is provided on the back surface of the photosensitive drum 222 and the transfer belt 216. The pressing roller 252 is arranged inside the transfer belt 216 on the side.

The configuration of the pressing roller 252 is such that both ends are supported by bearing members such as ball bearings (not shown), and an elastic rubber material or foam is formed on the shaft peripheral surface in a region longer than the longitudinal direction of the transfer belt 216. It is covered with an elastic body such as a resin material and is in contact with the photosensitive drum 222 with a uniform pressing force via the transfer belt 216.

The transfer belt 216 has a medium resistance (10 ⁷ to 10 ¹⁰ Ω · cm) and has little variation due to changes in environment and time (a high resistance belt may be used if a forced static elimination mechanism is provided). It is chemically stable and does not react with organic substances such as the photosensitive drum 222 and toner that come into direct contact. The cleaning member has durability (resistance to abrasion). A resin material having the above characteristics (for example, PI
PC etc.).

FIG. 6 is a schematic cross-sectional view of the structure in which the transfer belt 216 and the transfer input roller 251 are cleaned by the cleaning member 253.

There are various methods for removing toner and foreign matter adhering to the transfer input roller 251. In this embodiment, the cleaning blade 253 has been put to practical use in a wide range from low speed to high speed. A description will be given of a blade cleaning method in which toner is mechanically removed while being pressed, and a counter method in which cleaning performance is high and miniaturization is easy.

Cleaning blade cleaning 253
Is made of polyurethane rubber, and is assembled to the metal holder 254 by hot melt welding. The contact condition of the blade edge portion is arranged by optimizing the contact angle in consideration of the Young's modulus, Poisson's ratio, friction coefficient, and the like of the cleaning blade material.

As a means for cleaning toner and foreign matter adhered to the inside of the transfer belt 216, the transfer belt 21
6 is located upstream, for example, immediately before the position where the transfer input roller 251 is provided on the back surface side. The cleaning member (for example, a felt material) is pressed against the transfer belt 216 with a uniform and appropriate pressure.

As a result, there is no toner or foreign matter on the back surface of the transfer belt 216, so that the transfer input roller 25 on the downstream side is removed.
The bias to one transfer belt 216 can be made uniform,
Transfer unevenness can be suppressed.

Further, the cleaning means is connected to the support roller 214
By disposing the transfer roller 216 on the upstream side, for example, immediately before, the toner and foreign matter do not adhere to the surfaces of the support rollers 214 and 215, and it is possible to suppress rotation unevenness and plastic deformation of the transfer belt 216.

Next, a mechanism for contacting and separating the transfer input roller 251 and the cleaning blade 253 will be described.

In the black image recording section, a solenoid 255 or the like is disposed as moving means in a state where no voltage is applied to the transfer input roller 251, and the plunger section 256 of the solenoid 255 has an arm in contact with the blade unit 258. Holder 257 is linked and solenoid 2
When 55 is turned on, the arm holder 257 moves rightward in the drawing, whereby the blade unit 258 rises and comes into contact with the transfer input roller 251.

The spring 259 attached to the arm holder 257 is a return means for returning the arm holder 257 and the like to the original position.

Although not shown in the drawing, the blade unit 258 is attached by an elastic member such as a spring so as to always contact the arm holder 257 (the tensile load of the elastic member is smaller than the suction force of the solenoid 255). Is what it is.).

In the color image recording section, Y, M, C
The transfer input rollers 251a, 251b, 251c and the pressing rollers 252a, 252b, 252c are integrated with each other, and a lift mechanism for vertically moving the housing 260 is provided on the bottom surface of the housing 260.

A plurality of eccentric cams 262 and a gear 26 are mounted on a lift shaft 261 arranged in parallel with the transfer input roller 251.
Gear 3 is fixed, and the gear 2 is
Reference numeral 63 is connected so that the lift shaft 261 rotates clockwise or counterclockwise.

The number of lift shafts 261 is two in the figure, but may be more than one.
Timing belt 2 from the lift shaft 261 connected to
65 or a gear (not shown) and the like so that the rotational position and the angle are synchronized.

The contact and separation timings of the housing 260 are determined in the mode for recording a black image,
When cleaning the transfer input roller 251 (when the applied voltage is not input to the transfer input roller 251), the housing 260 moves downward and contacts the blade unit 258, and the cleaning operation of the transfer input roller 251 is started.

Although not shown, an elastic member such as a spring is attached to the housing 260 so as to always contact the eccentric cam 262.

After completion of the cleaning operation of the transfer input roller 251 and in the color image recording mode, the housing 26
The copy 0 moves upward and enters a copy standby state.

FIG. 7 is a schematic sectional view showing a state when a color image is formed by applying a voltage to the transfer input roller 251. FIG. 8 is a schematic configuration sectional view showing a state in which a brush roller 274 is in contact with the transfer input roller 251 and the transfer belt 216.

In FIG. 7, the transfer belt 216 near the transfer area of the photosensitive drum 222 is pressed against the transfer input roller 251 and the pressing roller 252 to perform copying. As shown in FIG. 8, the transfer input roller 251 is used. When cleaning is performed or when a black image is recorded, the housing 260 moves downward by the above-described means. At this time, the photosensitive drum 22 is transferred by the transfer input roller 251 and the pressing roller 252.
The pressure contact of the portion of the transfer belt 216 that has been pressed against 2 is released.

The transfer belt 216 is provided in the transfer / conveyance unit.
The belt tension roller 278 for equalizing the tension of the transfer belt 216 is provided even when the component accuracy such as the circumferential length variation of the support rollers 214 and 215 varies.
8 corrects the slack in the portion of the transfer belt 216 where the pressure contact has been released.
6 comes into contact with the cleaning member. ).

The structure of the belt tension roller 278 will be described. A belt tension arm 279 is provided so as to rotate about the axis of the support roller 215, and the transfer belt 21 is rotated.
6 is stretched from the front side (paper suction surface) by a tension spring 280 attached to the belt tension arm 279.

As described above, when the transfer input roller 251 moves from the transfer operation position to the cleaning blade 253 side, the transfer belt 216 also comes into contact with the cleaning blade 253, and the cleaning can be started at the same timing. It can be shortened.

Next, the structure of the brush roller 274 will be described.

A bias voltage having a polarity opposite to that of the toner is applied to the brush roller 274 and rotated, so that the brush roller 274 comes into contact with the front surface of the transfer input roller 252 and the back surface of the transfer belt 216. As a result, the tip of the brush roller 274 adsorbs the toner powder and foreign matter, the collecting roller 275 having a higher voltage than the brush roller 274 removes the toner powder and foreign matter on the brush roller 274, and finally the scraper blade 276 collects. The toner or foreign matter on the roller 275 is scraped and collected by a discharge toner bottle (not shown) by the transport screw 277.

Note that a PCC (pre-cleaning charger) may be disposed upstream of the brush roller 274 in order to increase the cleaning efficiency of the toner powder and foreign matters adhering to the transfer belt 216.

Brush roller 274 and collection roller 275
Is obtained by winding a conductive fiber around a metal core bar and then finishing the outer diameter of the core bar into a roll.

FIG. 9 is a schematic sectional view showing a state in the color image recording mode. FIG. 10 shows the transfer input roller 25.
FIG. 3 is a schematic cross-sectional view illustrating a state where a cleaning brush 270 and a cleaning blade 253 are in contact with each other.

When the transfer input roller 251 is connected to the transfer belt 216
When the cleaning member moves away from the transfer input roller 251
Another embodiment of the means for cleaning by contacting the surface will be described.

A belt cleaning brush 270 is disposed inside the transfer belt 216 upstream of a position (transfer area) having the transfer input roller 251 on the back surface of the photosensitive drum 222 and the transfer belt 216. The brush portion of the belt cleaning brush 270 is set to be longer than the axis of the transfer belt 216 in the longitudinal direction of the rotation shaft, and rotates clockwise or counterclockwise around the brush rotation fulcrum shaft 272 of the brush attachment holder 271. .

Normally (in a state where the housing 260 is raised), a torsion spring 273 is used to view the sectional view.
The load acts clockwise, and the belt cleaning brush 27
0 is parallel to the transfer belt 216 and cleans the back surface of the transfer belt 216. At this time, since the tip of the belt cleaning brush 270 is pressed against the transfer belt 216, it is bent in the rotation direction of the transfer belt 216 (leftward in FIG. 9).

When the housing 260 is the stepping motor 2
64 when moving downward (transfer input roller 251
Is separated from the transfer belt 216), the housing 260
Abuts on the brush attachment holder 271. At this time, since the force is larger than the rotation load value of the torsion spring 273, the brush attachment holder 271 rotates counterclockwise (about 90 degrees), and the belt cleaning brush 270 is rotated.
The unit comes into contact with the transfer input roller 251.

At this time, the belt cleaning brush 270
Is pressed against the transfer input roller 251.
Since the transfer input roller 251 rotates counterclockwise as viewed from the drawing, the transfer input roller 251 is bent in a direction opposite to when the belt cleaning brush 270 is cleaning the transfer belt 216. Thereby, the bending of the tip of the belt cleaning brush 270 is corrected, and the life of the belt cleaning brush 270 can be extended.

When the housing 260 rises, the brush attachment holder 271 also returns to the original position, and the back surface of the transfer belt 216 can be cleaned. The cleaning time and timing at this time can be set arbitrarily.

FIG. 11 is a schematic sectional view showing a state in which a voltage is applied to the transfer input roller 251. FIG. 12 is a perspective view of the transfer / conveyance unit. FIG. 13 shows the brush roller 2
FIG. 74 is a perspective view of FIG. FIG. 14 shows the cleaning brush 25.
3 is a perspective view of FIG.

Inside the transfer belt 216, both end portions are easily stained especially by toner or foreign matter wrapping around. Therefore, if the cleaning means is configured so that the cleaning action efficiency is higher near the both ends in the longitudinal direction of the rotation shaft of the cleaning means than near the center, the cleaning time can be reduced.

As a specific configuration, in the longitudinal direction of the rotation axis of the brush roller 274 as shown in FIG. 13, the brush flock density is reduced at the central portion 282 and increased at both ends 281 to clean the vicinity of both ends. The operation efficiency can be increased.

Further, by setting the parallelism of the edge portion of the cleaning blade 253 as shown in FIG. 14 so that the central portion is concave, it is possible to increase the efficiency of cleaning action near both ends in the same manner as described above. Can be.

Further, although not shown, it is also possible to change the electric charge amount by PCC (pre-cleaning charger) or the like to increase the efficiency of the cleaning operation at both ends.

[0115]

According to the first aspect of the present invention, the transfer medium cleaning means for cleaning the back side of the transfer medium is disposed upstream of the transfer means, and the back surface of the transfer medium immediately before the transfer medium comes into contact with the transfer means. By cleaning the toner, it is possible to apply a voltage to the transfer unit in a state where the wraparound toner and foreign matter are surely cleaned, so that the bias with respect to the transfer medium can be made uniform, and always good transferability can be secured. A highly reliable image can be obtained.

In the transfer device according to the second aspect, the transfer medium cleaning means for cleaning the back surface of the transfer medium has a cleaning action efficiency near both ends of the transfer medium that is larger than that at the center portion. Both ends of the back surface of the medium can be efficiently cleaned, and the cleaning time can be reduced.

The transfer device according to claim 3 cleans the back surface of the transfer medium when the cleaning means is at the first cleaning position, and
Since the transfer means is being cleaned when it is at the cleaning position, the cleaning means deformed in one direction by the transfer medium abuts on the transfer means and cleans the transfer means, so that it is deformed in the opposite direction to the above. It is possible to prevent the force applied to the cleaning unit from being applied only in one direction, prevent the cleaning unit from being deformed in one direction, and extend the life of the cleaning unit.

In the transfer device according to the fourth aspect, the cleaning means is disposed upstream of the support roller for supporting the transfer medium, and the back surface of the transfer medium is cleaned immediately before the transfer medium comes into contact with the support roller. Since the wraparound toner and foreign matter are sent to the support roller in a state of being reliably cleaned, slippage between the transfer medium and the support roller is prevented, and transfer is performed by pinching foreign matter and the like between the transfer medium and the support roller. Vibration and rotation unevenness of the medium can be prevented, the transfer medium can always be stably transported, and a highly reliable image can be obtained.

In the transfer device according to the fifth aspect, the transfer medium is also moved by the movement of the transfer means to the second position, and the transfer means and the transfer medium simultaneously contact the cleaning means. The transfer medium is cleaned, so that the warming time can be reduced by shortening the cleaning time, and the configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing the entire structure of a digital color copying machine which is an image forming apparatus of the present invention.

FIG. 2 is a block diagram of an image data processing system of the digital color copying machine of the present invention.

FIG. 3 is a control block diagram of the digital color copying machine of the present invention.

FIG. 4 is a plan view of an operation panel of the digital color copying machine of the present invention.

FIG. 5 is a schematic cross-sectional view of the vicinity of a transfer unit in a digital color copying machine according to an embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view illustrating a state in which a transfer belt and a transfer input roller are cleaned in a digital color copying machine according to an embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view illustrating a configuration of the digital color copying machine according to the embodiment of the present invention during image formation.

FIG. 8 is a schematic cross-sectional view showing a configuration of a digital color copying machine according to another embodiment of the present invention when a transfer belt and a transfer input roller are cleaned.

FIG. 9 is a schematic cross-sectional view showing a configuration of a digital color copying machine according to another embodiment of the present invention when a transfer belt is cleaned.

FIG. 10 is a schematic cross-sectional view illustrating a state in which a transfer input roller is cleaned in another embodiment of the digital color copying machine of the present invention.

FIG. 11 is a schematic sectional view showing a brush roller in another embodiment of the digital color copying machine of the present invention.

FIG. 12 is a perspective view showing a transfer and transport unit in another embodiment of the digital color copying machine of the present invention.

FIG. 13 is a perspective view showing a brush roller in another embodiment of the digital color copying machine of the present invention.

FIG. 14 is a perspective view showing a brush roller in another embodiment of the digital color copying machine of the present invention.

[Explanation of symbols]

 216 Transfer Conveying Belt 222 Photosensitive Drum 250 Conductive Roller 251 Transfer Input Roller 252 Pressing Roller 253 Cleaning Blade 254 Metal Holder 255 Solenoid 256 Plunger 257 Arm Holder 258 Blade Unit 259 Spring 260 Housing 261 Lift Shaft 262 Eccentric Cam 263 Gear 264 Stepping Motor 270 Cleaning brush 271 Brush mounting holder 272 Brush rotation fulcrum shaft 273 Torsion spring 274 Brush roller 275 Collection roller

Claims (5)

[Claims] 1. A transfer device for transferring an image formed on an image carrier to a transfer material, wherein the transfer device is stretched between at least two support rollers and is disposed close to a transfer area of the image carrier. A transfer medium that presses the transfer medium from the back side of the transfer medium toward the transfer area of the image carrier; Cleaning means for acting on the back side of the transfer medium to clean the back side of the transfer medium before the transfer medium is guided to a portion where the transfer medium is pressed against the transfer area of the body. Transfer device. 2. The transfer device according to claim 1, wherein the cleaning means has a cleaning action efficiency that is greater in the vicinity of both ends in the direction perpendicular to the transfer movement direction of the transfer medium than in the center. apparatus. 3. The cleaning device according to claim 1, wherein the cleaning unit is positioned upstream of the transfer medium in a direction in which the transfer medium is conveyed. A first cleaning position for cleaning the back surface of the transfer medium by acting on the back surface side of the transfer medium; and a second cleaning position for cleaning the transfer means by acting on the front surface of the transfer means. The transfer device according to claim 1, wherein: 4. A transfer device for transferring an image formed on an image carrier to a transfer material, wherein the transfer device is stretched between at least two support rollers and is disposed close to a transfer area of the image carrier. Transfer medium, transfer means for pressing the transfer medium from the back side of the transfer medium toward the transfer area of the image carrier, and supporting the transfer medium in a stretched manner on the upstream side in the moving and conveying direction of the transfer medium. A transfer medium cleaning unit that acts on the back side of the transfer medium to clean the back side of the transfer medium before the transfer medium is guided to a portion where the support roller acts on the transfer medium; apparatus. 5. A transfer device for transferring an image formed on an image carrier onto a transfer material, wherein the transfer device is stretched between at least two support rollers and is disposed in proximity to a transfer area of the image carrier. A transfer medium, a first position for pressing the transfer medium from the back side of the transfer medium toward the transfer region of the image carrier, and releasing the transfer medium by pressing the transfer medium against the image carrier. A transfer unit movable between a second position retracted from the back surface, and a transfer unit located upstream of the transfer unit in the transporting direction of the transfer unit, and when the transfer unit moves to the second position, A transfer device, wherein the transfer device is provided with cleaning means for releasing the pressing of the image carrier by the movement of the transfer means and abutting against the back surface of the transferred transfer medium to clean the transfer means and the back surface of the transfer medium. .