JP3524310B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer.

[0002]

2. Description of the Related Art With reference to FIG. 5, an outline of a conventional image forming apparatus will be described by taking a color laser beam printer as an example.

Image forming apparatus body (hereinafter simply referred to as "apparatus body")
A paper feeding unit 101 is provided below the (109). The paper feeding unit 101 is for feeding a transfer material 102 to a transfer drum 103, which will be described later, and has a paper feeding cassette 101a containing the transfer material 102 detachably attached thereto. During image formation, the paper feed roller 101b rotates according to the image forming operation, and the transfer materials 102 are separated one by one from the paper feed cassette 101a and fed to the transfer drum 103.

A photosensitive drum (image carrier) 104a is rotatably arranged in the direction of the arrow (counterclockwise) in the substantial center of the apparatus main body 109, and the primary charger 1 is provided above the photosensitive drum 104a.
04b is provided. The primary charger is one in which a charging roller 104b to which a voltage is applied is brought into pressure contact with the photosensitive drum 104a, and the photosensitive drum 10 is formed prior to the formation of an electrostatic latent image.
4a Surface is uniformly charged.

The exposure of the photosensitive drum 104a is performed by the scanner section 110 having a laser diode 110a. The laser diode 110a emits light corresponding to the image signal and irradiates the polygon mirror with the laser light L. The polygon mirror is rotated at a high speed by a scanner motor and reflects the laser light L. The laser light L reflected by the polygon mirror selectively exposes the surface of the photosensitive drum 104a through a coupling lens 110b and a reflection mirror 110c in accordance with an image signal. The photosensitive drum 104a forms an electrostatic latent image of each color by exposure to the laser light L.

The electrostatic latent image of each color is developed by the rotary developing device 105. The rotary developing device 105 includes developing devices 105M, 105C and 105Y, which are provided with developing devices of respective colors and magenta, cyan, yellow and black toners, respectively.
Has 105K. These four color developing units are equipped with a shaft 10
It is mounted on a rotating body 105b that rotates about 5e, and rotates about the shaft 105e while the posture shown in the figure is maintained as the rotating body 105b rotates. These four color developing devices have a constant toner capacity so that the torque distribution with respect to the shaft 105e is constant.
Toner for printing about 2000 images is stored. At the time of development, the rotation of the rotating body 105b moves the developing device 105 of the color corresponding to the electrostatic latent image to the developing position facing the photosensitive drum 104a, and further, the developing sleeve 105a forms a minute gap with the surface of the photosensitive drum 104a. Are positioned so as to face each other. When the developing device is rotationally moved to the developing position, the developing sleeve 105a
Is connected to a high voltage power source of the apparatus main body 109 to apply a developing bias, and at the same time, is also connected to a driving unit to perform a predetermined rotation. At the time of development, the developing sleeve 105a receives the application of a developing bias and the rotational drive, so that the photosensitive drum 1
Toner is attached to the electrostatic latent image on 04a and developed as a toner image.

The toner image is transferred onto the transfer material 102 carried on the transfer drum 103. The transfer drum 103 winds the transfer material 102 fed from the paper feeding unit 101, and in order to transfer the toner image of each color on the photosensitive drum 104a onto the transfer material 102 at the transfer unit, the peripheral speed of the photosensitive drum 104a. It rotates in the arrow direction (clockwise) at the same peripheral speed as V = 75.4 mm / sec (hereinafter referred to as “process speed”). The transfer drum 103 includes an elastic layer 1 made of sponge, rubber or the like on the outer circumference of an aluminum cylinder 103a having a diameter of 180 mm.
03b is formed, and the resistance layer 103c is formed on the outer periphery thereof,
Further, a dielectric layer 103d is formed on the outermost layer. Further, a gripper 103f that holds the leading end of the fed transfer material 102 is provided at a predetermined position on the outer periphery of the transfer drum 103. Further, an electrostatic attraction roller 103g is provided on the outer periphery of the transfer drum 103 so as to be able to come into contact with and separate from the transfer drum 103, and the electrostatic attraction roller 103g transfers the transfer material 102 to the transfer drum 10.
It is pressed against the outer peripheral surface of the transfer drum 103 so as to be sandwiched between the transfer drum 103 and the transfer drum 103. Then, by applying a voltage between the electrostatic attraction roller 103g and the transfer drum 103, the transfer material 102, which is a dielectric, and the dielectric layer 10 of the transfer drum 103.
3d induces an electric charge to transfer the transfer material 102 to the transfer drum 10.
3 is electrostatically attracted to the outer peripheral surface. The toner image formed on the surface of the photosensitive drum 104 described above is transferred to the transfer material 102 electrostatically attracted to the outer peripheral surface of the transfer drum 103.

The cleaner 104d is for cleaning the residual toner remaining on the surface of the photosensitive drum 104a after the toner image is transferred, and the photosensitive drum 10 downstream of the transfer portion.
It is arranged on the outer periphery of 4a. A cleaning blade 104c is also provided as a member for removing the residual toner.

The fixing unit 106 is driven by the pressure roller 10.
6a and a fixing roller 106b that is in pressure contact with the transfer material 102 to apply heat and pressure to the transfer material 102. The toner images of respective colors are fixed to the transfer material 102 by holding the toner images of the respective colors and passing through the transfer material 102 which is separated and conveyed from the transfer drum 103.

The image forming operation is performed by the paper feeding cassette 10.
The transfer material 102 in 1a is fed to the transfer drum 103 by the paper feed roller 101b. The transfer drum 103 grips the front end of the transferred transfer material 102 with a gripper 103f and electrostatically adsorbs it on the outer peripheral surface thereof. On the other hand, the photosensitive drum 1 whose surface is uniformly charged by the primary charger 104b
The scanner unit 110 exposes the magenta image 04a to form an electrostatic latent image for the magenta image on its outer peripheral surface. At the same time as this electrostatic latent image formation, the magenta developing device 105M
The photosensitive drum 1 so that the magenta toner adheres to the magenta electrostatic latent image formed on the photosensitive drum 104a.
A developing bias voltage having the same polarity as the charging polarity of 04a and having substantially the same potential is applied to develop, and a magenta toner image is obtained on the photosensitive drum 104a. Then, a transfer voltage having a polarity opposite to that of the magenta toner is applied to the transfer drum 103, and the photosensitive drum 10
The magenta toner image on 4a is transferred to the transfer material 102 on the transfer drum 103.

When the transfer of the magenta toner image is completed, the next developing device 105C rotates and is positioned at the developing position facing the photosensitive drum 104a, and in the same process, formation of a cyan electrostatic latent image, development, and cyan toner are performed. The images are sequentially transferred and transferred onto the transfer material 102. Further, the same process is performed for yellow and black toners to form a four-color full-color image on the transfer material 102. That is, the transfer drum 1 that grips and holds the transfer material 102
By rotating the 04a four times, one full-color image of four colors can be obtained.
One full color is output at 0π × 4 / 75.4).

Transfer material 10 after transfer of four-color toner image is completed.
2 is separated from the transfer drum 103 and conveyed to the fixing unit 106, where the toner image is fixed by the fixing unit 106, and then discharged onto the discharge tray 108 by the discharge roller pair 107.

In the image forming apparatus having the above-described structure, in order to shorten the image forming time, the transfer material 10 having a short length in the conveying direction is used.
In the case of performing image formation on No. 2, two toner images of the transfer material 102 are formed on the surface of the intermediate transfer member 103, and the toner images are transferred to two continuous transfer materials 102, and the image forming time per one sheet is set. There is a known technique for shortening the power consumption by half.

[0014]

However, according to the above-mentioned conventional example, one of the two toner images on the intermediate transfer member 103 is transferred to the first transfer material 102. After that, when the transfer material runs out or the transfer material is clogged, the toner image that should originally be transferred to the second transfer material 102 is removed from the intermediate transfer body 103. When the image forming apparatus is restarted after the clogging process, the same toner image has to be formed again, and there is a problem that speedup at the time of restart cannot be achieved.

Further, there is a problem that the untransferred toner image on the intermediate transfer body may contaminate the transfer means or deteriorate the intermediate transfer body.

Therefore, it is an object of the present invention to provide an image forming apparatus that speeds up restarting, prevents contamination of transfer means, and prevents deterioration of an intermediate transfer member.

[0017]

The present invention according to claim 1 provides an intermediate transfer member carrying a toner image, and the intermediate transfer member.
Transfer means for transferring the toner image on a transfer material, and
Cleaning hand that cleans the toner image on the transfer body
An image forming apparatus having a step and capable of recognizing replenishment of a transfer material.
In the transfer, the toner image on the intermediate transfer member is transferred.
When the material is not supplied to the transfer means, the intermediate transfer member
The toner image is held on the upper surface of the intermediate transfer member.
The time from the start of holding until the transfer material is replenished
Depending on whether or not a certain time has passed, the intermediate transfer member
The toner image of No. 1 is transferred to the transfer material by the transfer unit.
Or whether to remove by the cleaning means
Obtain, characterized in that.

The present invention according to claim 2 is as described in claim 1.
In the image forming apparatus, the intermediate transfer member is at least
To carry a toner image to be transferred onto two or more transfer materials
The feature is that

The present invention according to claim 3 provides the invention according to claim 1 or 2.
In the image forming apparatus described in, it is confirmed that there is no transfer material.
Recognizes the subsequent replenishment of the transfer material, if
That, characterized in that.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the transfer is performed.
When the jam is processed, the transfer material
It is characterized by recognizing replenishment .

[0021]

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> [General Description of Image Forming Apparatus] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to the present invention. The image forming apparatus shown in the figure is a four-color full-color laser beam printer.

The image forming apparatus shown in FIG. 1 has a drum type inside the image forming apparatus main body (hereinafter simply referred to as "apparatus main body") as an image carrier that rotates in a direction of an arrow (clockwise) at a predetermined process speed. An electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 15 is provided. Around the photosensitive drum 15, an image forming portion having a fixed black developing device 21B and three rotatable color developing devices 20Y, 20M and 20C, and a primary transfer which is developed by this image forming portion. Further, an intermediate transfer body 9 is provided for carrying out secondary transfer to the transfer material 2 fed from the paper feed cassette 1 of the feeding portion while holding the multiple color toner images. The transfer material 2 onto which the color toner image has been transferred by the intermediate transfer member 9 is then conveyed to the fixing device 25, where the toner image is fixed, and then discharged onto the discharge tray 37 on the upper surface of the apparatus main body by the discharge roller 36. To be done. The rotatable color developing devices 20Y, 20M, and 20C and the fixed black developing device 21B are configured to be individually attachable to and detachable from the apparatus main body.

Next, the structure of each part of the image forming apparatus will be sequentially described in detail. [Image Carrier Unit] The drum unit (image carrier unit) 13 includes a photosensitive drum 15 and a cleaning container 14 of a cleaning device that also serves as a holder for the photosensitive drum 15.
The drum unit 13 is detachably supported with respect to the apparatus main body, and the unit can be easily replaced according to the life of the photosensitive drum 15. . The photosensitive drum 15 according to the present embodiment is configured by applying an organic photoconductor layer 11 on the outside of an aluminum cylinder 12 having a diameter of about 60 mm, and is freely rotatable by a cleaning container 14 of a cleaning device that also serves as a holder for the photosensitive drum 15. Supported by. A cleaning blade 16 and a primary charging roller (charging means) 1 are provided on the outer peripheral surface (front surface) of the photosensitive drum 15.
7 are arranged. The photosensitive drum 15 is rotated counterclockwise in the figure in accordance with an image forming operation by transmitting a driving force of a driving motor (not shown) disposed at one end on the rear side in the figure. [Charging Means] As a charging means, a conductive charging roller 17 is used.
Is applied to the surface of the photosensitive drum 15 by a so-called contact charging method. By applying a voltage to the charging roller 17, the surface of the photosensitive drum 15 has a predetermined polarity.
It is uniformly charged to a predetermined potential. [Exposure Unit] The exposure of the photosensitive drum 15 is performed by the scanner unit 30. That is, when an image signal is given to a laser diode (not shown), the laser diode irradiates the polygon mirror 31 with image light corresponding to the image signal. The polygon mirror 31 is rotated at a high speed by a scanner motor, and the image light reflected by the polygon mirror 31 is rotated at a predetermined process speed via an imaging lens 32 and a reflection mirror 33.
5, the surface of the photosensitive drum 15 is exposed selectively.
An electrostatic latent image is formed on the surface. [Developing Unit] The developing unit includes three developing units 20 for developing with the toners of yellow, magenta, and cyan colors in order to visualize the electrostatic latent image as a toner image.
It is provided with Y, 20M, and 20C, and one developing device 21B for developing with black toner.

The black developing device 21B is a fixed developing device, and the developing sleeve 21BS is located at a developing position facing the photosensitive drum 15 with a minute gap (300 μm) from the photosensitive drum 15.
The black toner image is formed by adhering black toner to the electrostatic latent image on the photosensitive drum 15. The developing device 21B feeds the toner in the container by a feeding mechanism, and applies a thin toner layer on the outer circumference of the developing sleeve 21BS rotating clockwise in the figure by the applying blade 21BB pressed against the outer circumference of the developing sleeve 21BS. Charge (frictional charging). Further, by applying a developing bias to the developing sleeve 21BS, toner development is performed corresponding to the electrostatic latent image on the photosensitive drum 15.

Three rotary developing devices 20Y, 20M, 20C
Each contain toner corresponding to 4000 pages (A4, 5% printing), and are detachably mounted on a developing rotary 23 that rotates about an axis 22. At the time of development, each of the developing devices is rotationally moved in accordance with the rotation of the developing rotary 23, the predetermined developing device provided for the development stops at the developing position facing the photosensitive drum 15, and the developing sleeve is attached to the photosensitive drum 15. After being positioned so as to face each other with a minute gap (about 300 μm), the photosensitive drum 1
A toner image corresponding to the electrostatic latent image of No. 5 is formed. At the time of forming a color image, the developing rotary 23 rotates for each rotation of the intermediate transfer member 9, and the yellow developing device 20Y, the magenta developing device 20M, the cyan developing device 20C, and then the black developing device 20B.
The developing process is performed in this order.

FIG. 1 shows a state where the yellow developing device 20Y is positioned and stationary at the developing position facing the photosensitive drum 15. The developing device 20Y sends the toner in the developing container to the coating roller 20YR by a feeding mechanism, and rotates the coating roller 20YR rotating clockwise in the figure, and the blade 20YB pressed against the outer circumference of the developing sleeve 20YS.
By the developing sleeve 20 that rotates clockwise in the figure.
A thin layer of toner is applied to the outer periphery of YS, and an electric charge is applied to the toner (friction charging). By applying a developing bias to the developing sleeve 20YS facing the photosensitive drum 15 on which the electrostatic latent image is formed, the photosensitive drum 1 can be formed according to the electrostatic latent image.
Toner is attached to the surface of the electrostatic latent image to develop the electrostatic latent image. The magenta developing device 20M and the cyan developing device 20C are also developed by magenta and cyan toners by the same mechanism as described above.

The developing sleeves of the developing devices 20Y, 20M, and 20C are connected to a high-voltage power source and a driving means provided in the apparatus main body for developing each color when the developing devices are rotationally moved to the developing position. Is configured to
A voltage is applied selectively and a driving force is transmitted sequentially for each development of each color toner image. [Intermediate Transfer Member] The intermediate transfer member 9 is a photosensitive drum 15 that is sequentially developed by each developing device during a color image forming operation.
Since the upper yellow, magenta, cyan, and black toner images are subjected to multiple transfer of four times in total, the photosensitive drum 1
The intermediate transfer body 9 that rotates in the direction of the arrow (clockwise in the figure) in synchronization with the process speed of 5 and has undergone multiple transfer is sandwiched and conveyed by the transfer roller 10 to which a voltage is applied. Secondary transfer (simultaneous multiple transfer) of each color toner image on the intermediate transfer member 9 is collectively performed on the transfer material 2.

The intermediate transfer member 9 in this embodiment has a structure in which the outer circumference of an aluminum cylinder 12 having a diameter of 180 mm is covered with an elastic layer 11 such as medium resistance sponge or medium resistance rubber. The intermediate transfer body 9 is rotatably supported, and is rotated in the arrow direction by being driven by a gear (not shown) integrally fixed to the intermediate transfer body 9. [Cleaning Means] The cleaning means remains on the photosensitive drum 15 without being transferred to the intermediate transfer body 9 after the toner image formed on the surface of the photosensitive drum 15 by each of the developing devices is transferred to the intermediate transfer body 9. To remove the residual toner, the swingable cleaning roller 40 abuts the intermediate transfer body 9 at the position shown in the figure, and the toner reverse biased is reversely transferred to the photosensitive drum 15 and stored in the cleaning container 14. To be The amount of waste toner that can be stored in the cleaning container 14 depends on the amount of waste toner before the photosensitive drum 15 reaches the end of its life.
4 is set so that the cleaning container 14 is not replaced at the same time when the life of the photosensitive drum 15 is replaced. [Paper Feeding Unit] The paper feeding unit feeds the transfer material 2 to the image forming unit, and the paper feeding cassette 1 containing a plurality of transfer materials 2
A sheet feeding roller 3, a feeding roller 4, a retarding roller 5 for preventing double feeding, a sheet feeding guide 6, a conveying roller 7, a registration roller 8 and the like are main components. At the time of image formation, the paper feed roller 3 is driven and rotated in accordance with the image forming operation to separate and feed the transfer materials 2 in the paper feed cassette 1 one by one, and guide them by the paper feed guide 6 and pass through the conveyance roller 7. Then, the registration roller 8 is reached. During the image forming operation, the registration roller 8 performs a non-rotating operation for holding the transfer material 2 in a stationary state and a rotating operation for conveying the transfer material 2 toward the intermediate transfer body 9 in a predetermined sequence, which is the next step. The toner image on the photosensitive drum 15 and the transfer material 2 are aligned during the transfer process. [Transfer Section] The transfer section includes a swingable transfer roller 10. The transfer roller 10 has a metal shaft wound with a medium-resistance foamed elastic body, is supported substantially vertically in the direction of arrow K10 in the figure, and is rotationally driven by a drive unit (not shown). The transfer roller 10 is shown by a solid line in the figure so as not to disturb the toner image while forming the toner images of four colors on the above-mentioned intermediate transfer body 9, that is, while the intermediate transfer body 9 makes a plurality of rotations. It is located at the lower release position and is separated from the intermediate transfer body 9. On the other hand, the transfer roller 10 transfers the transfer material 2 after the toner images of four colors are formed on the intermediate transfer member 9.
A cam member (not shown) is arranged at an upper operating position shown by a broken line 10b in the drawing, that is, one for pressing the intermediate transfer body 9 with a predetermined pressure through the transfer material 2 in accordance with the timing of transferring the toner image to To be done. At this time, a bias is simultaneously applied to the transfer roller 10, and the toner image on the intermediate transfer body 9 is transferred to the transfer material 2. Here, since the intermediate transfer member 9 and the transfer roller 10 are respectively driven, the transfer material 2 sandwiched between the two is simultaneously conveyed at the predetermined speed in the left direction in the drawing at the same time as the transfer step is performed. , And is conveyed toward the fixing device 25 where the next process is performed. [Fixing Unit] The fixing device (fixing unit) 25 fixes the toner images of four colors secondarily transferred from the surface of the photosensitive drum 15 onto the transfer material 2 by the transfer roller 10 described above. 2, a fixing roller 26 for applying heat to the transfer material 2 and a pressure roller 27 for pressing the transfer material 2 to the fixing roller 26 are provided. Each of the rollers 26, 27 is a hollow roller and is internally It has heaters 28 and 29 and is configured to be rotationally driven and simultaneously convey the transfer material 2.

That is, the transfer material 2 carrying the unfixed toner image after the transfer is conveyed by the fixing roller 26 and the pressure roller 27 and is heated and pressed, so that the toner of four colors is formed on the surface. The image is fused and fixed. [Image Forming Operation] Next, an image forming operation by the image forming apparatus having the above configuration will be described.

First, the sheet feeding roller 3 shown in FIG. 1 is rotated to separate one sheet of the transfer material 2 in the sheet feeding cassette 1, and the sheet is conveyed to the registration roller 8.

On the other hand, the photosensitive drum 15 and the intermediate transfer member 9 rotate counterclockwise and clockwise in the figure at a process speed V = 75.4 mm / sec. The photosensitive drum 15 having a diameter of 60 mm rotates once in 60π / 75.4≈2.5 seconds, and the intermediate transfer member 9 having a diameter of 180 mm is 180π / 7.
It makes one rotation in 5.4≈7.5 seconds. Further, since the photosensitive drum 15 and the intermediate transfer body 9 are meshed with each other, the gears integral with each other mesh, so that when the photosensitive drum 15 rotates three times, the intermediate transfer body 9 is rotated.
Rotates exactly once.

As shown in FIG. 1, in the photosensitive drum 15 whose surface is uniformly charged by the charging roller 17, when an arbitrary point S on the outer peripheral surface of the intermediate transfer body 9 reaches a position S in the figure, Laser exposure is performed at the exposure position E in the figure to start drawing an electrostatic latent image (the point on this photosensitive drum is designated as point E). The distance a from the exposure position E of the photosensitive drum 15 counterclockwise to the primary transfer position T1 with the intermediate transfer body 9 and the distance b from the position S of the intermediate transfer body 9 to the clockwise primary transfer position T1 are Therefore, the point E at the beginning of drawing the electrostatic latent image and the point S on the intermediate transfer body 9 are equal to each other after a predetermined time has elapsed.
They match at the next transfer position T1. That is, the toner image is formed clockwise on the intermediate transfer body 9 with the point S as the tip. Formation of yellow toner image The scanner unit 30 irradiates yellow laser light to form a yellow electrostatic latent image on the photosensitive drum 15. Simultaneously with the formation of the electrostatic latent image, the yellow developing device 20Y is driven to apply a voltage having the same polarity as the charging polarity of the photosensitive drum 15 and substantially the same potential so that the yellow toner adheres to the electrostatic latent image on the photosensitive drum 15. And a yellow toner image is formed. At the same time, the yellow toner image on the photosensitive drum 15 is primarily transferred to the outer peripheral surface of the intermediate transfer body 9 at the primary transfer position T1 slightly downstream of the developing section. At this time, a voltage having a polarity opposite to that of the yellow toner image is applied to the intermediate transfer member 9 to perform the primary transfer.

When the image to be formed is of A3 size, the length in the carrying direction is 420 mm, and the image is formed from points S to L1 on the outer peripheral surface of the intermediate transfer member 9. When the transfer of the yellow toner image to the intermediate transfer member 9 is completed, that is, when L1 has passed the primary transfer position T1, the developing rotary 23 rotates clockwise, and the next magenta developing device 20M rotationally moves, and the photosensitive drum It is positioned at the developing position opposite to 15. Formation of magenta toner image Next, when one point S (the tip of the yellow toner image) of the outer peripheral surface of the intermediate transfer member 9 makes one round and reaches the position of the point S in the figure, the scanner unit 30 similarly uses magenta toner images. Laser irradiation is started, an electrostatic latent image is formed on the photosensitive drum 15 in the same manner as yellow, the electrostatic latent image is developed as a magenta toner image, and the magenta toner image on the photosensitive drum 15 is primarily Similarly, the image is transferred onto the intermediate transfer member 9 at the transfer position T1. When the transfer of the magenta toner image to the intermediate transfer body 9 is completed, that is, when L1 has passed the primary transfer position T1, the developing rotary 23 rotates clockwise, and the next cyan developing device 20C rotationally moves, and the photosensitive drum It is positioned at the developing position opposite to 15. Formation of Cyan Toner Image Next, when a point S (the tip of the yellow and magenta toner images) on the outer peripheral surface of the intermediate transfer body 9 further makes a further revolution to reach the position S in the figure, the scanner unit 30 similarly uses cyan. Laser irradiation is started, an electrostatic latent image is formed on the photosensitive drum 15 similarly to magenta, and the electrostatic latent image is developed as a cyan toner image.
The upper cyan toner image is transferred to the intermediate transfer member 9 at the primary transfer position T1.
Primary transfer is performed so as to overlap with the yellow and magenta toner images. When the transfer of the cyan toner onto the intermediate transfer body 9 is completed, that is, when L1 has passed the primary transfer position T1, the developing rotary 23 rotates 60 degrees counterclockwise and the developing position facing the photosensitive drum 15 is colored. There is no developing unit. Formation of Black Toner Image Next, when a point S (the tip of the yellow, magenta, and cyan toner images) on the outer peripheral surface of the intermediate transfer body 9 makes another round and reaches the position S in the figure, the scanner unit 30 is similarly operated. Then, the laser irradiation for black is started to form a black electrostatic latent image, and the electrostatic latent image is developed as a black toner image by the black developing device 21B, and the black toner image on the photosensitive drum 15 is formed. The images are further transferred and transferred onto the intermediate transfer member 9 at the primary transfer position T1.

As described above, for each color in the order of yellow, magenta, cyan, and black, primary charging, electrostatic latent image formation, development, and primary transfer of the toner image to the intermediate transfer body 9 are sequentially performed four times in total. Then, on the surface of the intermediate transfer member 9, a full-color image including four color toner images of yellow, magenta, cyan, and black is formed.

1 of the black toner image on the intermediate transfer member 9
Before the next transfer is completed, that is, before the image front end S of the intermediate transfer body 9 that has completed the primary transfer of the black toner image of the fourth color and formed the full-color image reaches the secondary transfer position T2, The transfer material 2 that has been waiting at 8 is started to be conveyed at the same timing. At the same time, at the time of primary transfer of the toner images of the respective colors onto the intermediate transfer member 9 for the above-mentioned four times, the intermediate transfer member 9 is waited at the lower releasing position.
The transfer roller 10 which is in a non-contact state is moved upward by a cam (not shown) to press the transfer material 2 at the secondary transfer position T2 of the intermediate transfer body 9 and at the same time, the transfer roller 10 reverses the toner to the toner. By applying a polarity bias, the four color toner images on the intermediate transfer member 9 are secondarily transferred onto the transfer material 2 all at once. The transfer material 2 that has passed through the secondary transfer position T2 is separated from the intermediate transfer body 9, is conveyed to the fixing device 25, and the toner images of four colors are fixed, and then the discharge roller pair 34, 35 ,.
The image forming surface is discharged downward onto the discharge tray 37 on the upper surface of the apparatus main body via 36, and the image forming operation is completed.

It can be seen that the intermediate transfer member 9 basically requires four rotations and a time of 30 seconds (7.5 seconds × 4) in order to form one full-color image in this way. . By the way, the intermediate transfer body 9 and the photosensitive drum 15 driven at the same process speed V rotate 12 times in inverse proportion to the outer diameter ratio with the intermediate transfer body 9 for producing one full-color image.

The intermediate transfer member 9 has a diameter of 180 mm,
When the image is formed on the A3 size transfer material 2 having the outer peripheral length of about 565 mm and the length in the carrying direction of 420 mm, the outer peripheral length of 565 mm is 420 mm. That is, the distance from the point S on the outer peripheral surface of the intermediate transfer member 9 to the point L1 counterclockwise is 420 mm. That is, of the outer circumference 565 mm of the intermediate transfer member 9, 420 mm is used for image formation and the remaining 145 mm is not used for image formation. Since the intermediate transfer member 9 rotates at a constant process speed V = 75.4 mm / sec,
For forming a full-color image of three sizes, 145/75.
There is a non-image forming time of 4 = 1.92 seconds, and this time is applied to the switching time of the color developing devices 20Y, 20M and 20C.

Laser exposure position E of photosensitive drum 15 and 1
The developing device 20Y located between the next transfer position T1 and the developing device 20Y forms a toner image, and the time applied to replace the developing device 20M is L1 of the intermediate transfer member 9 although the actual timing is shifted. The point corresponds to the time until the point passes through the primary transfer position T1 and the point S reaches the primary transfer position T1.

Here, when a small-sized transfer material 2 having a length in the transport direction shorter than 1/2 of the outer peripheral length of the intermediate transfer body 9 is used, the transfer material 2 is transferred onto the intermediate transfer body 9 as shown in FIG. Material 2 of 2
It is possible to form toner images V1 and V2 for one sheet.

That is, by feeding two sheets of the small-sized transfer material 2 continuously at appropriate time intervals, it is possible to print two sheets in one time of the above-mentioned image forming process (hereinafter, "2 sheets"). Paste sequence ").

FIG. 3 shows a flowchart in the two-sheet pasting sequence. Transfer material 2 in the two-sheet pasting sequence
The sheet feeding operation is started after the toner images V1 and V2 are simultaneously formed on the intermediate transfer body 9 (S1).

Therefore, if the transfer material 2 of the first sheet is fed at this time, the paper runs out (paper cut occurs) 2
When the first transfer material 2 is not fed (S2), the transfer roller 10 is retracted from the operating position indicated by the broken line 10b to the release position indicated by the solid line when the first transfer material has finished passing the secondary transfer position T2. Then (S3), the entire image forming apparatus is placed in a standby state. By doing so, it is formed on the intermediate transfer member 9,
The toner image V2 to be transferred to the second transfer material 9 is held on the intermediate transfer body 9 as it is, and
Since the transfer roller 10 is separated from the intermediate transfer body 9, the toner image V2 on the intermediate transfer body 9 does not contaminate the transfer roller 10.

Next, if the transfer material 2 is replenished within a fixed time after the image forming apparatus is in the standby state (S
5), the paper feeding operation is restarted (S6), and the toner image V to be transferred to the second toner image held on the intermediate transfer body 9 is transferred.
2 can be transferred to the transfer material 2.

On the other hand, if the transfer material 2 is not replenished within a fixed time (S5), and if the transfer material 2 can be fed from another paper feeding means (S7), the paper is re-fed from there. If it is not possible (S8), the cleaning roller 40 shown in FIG. 2 is moved to the position of the dotted line 40b in FIG. 2 and brought into contact with the intermediate transfer body 9, and the cleaning sequence is started (S9). As a result, the charged toner image V2
Is prevented from deteriorating due to being carried on the surface for a long time. In addition, when the paper is out after the second sheet is fed, the toner image V is fed to the second sheet.
After 2 is transferred, a standby state is set (S4).

Next, FIG. 4 shows a flowchart when the apparatus main body is stopped due to paper jam or the like. If the apparatus main body is stopped due to a paper jam or the like before the fed transfer material 2 reaches the secondary transfer position T2 (S11, S12), the transfer roller 10 is similarly retracted to the release position indicated by the solid line (S1).
3) Put the image forming apparatus in a standby state. By doing so, the toner images V1 and V2 on the intermediate transfer body 9 are held, and the transfer roller 10 can be prevented from being soiled by these toner images V1 and V2.

If the paper jam is processed within a fixed time after the image forming apparatus is in the standby state (S1
5) The paper feeding operation is restarted (S16), and the toner images V1 and V2 held on the intermediate transfer body 9 can be transferred to the transfer material.

On the other hand, when the paper jam is not dealt with within the fixed time (S15), the cleaning roller 40 is brought into contact with the intermediate transfer member 9 to perform the cleaning sequence (S).
In step 17), the toner image on the intermediate transfer body 9 is removed to prevent the intermediate transfer body 9 from being deteriorated due to the toner image remaining on the intermediate transfer body 9 for a long time.

When the image forming apparatus is on standby due to paper shortage or paper jam in the above-described two-sheet pasting sequence, the photosensitive drum 15 and the intermediate transfer member 9 are brought into contact with each other in the non-image area N as shown in FIG. If you do, holding the toner image,
It is possible to prevent deterioration due to toner adhesion to the photosensitive drum 15 for a long period of time. Further, since the toner image once formed on the intermediate transfer body 9 is used without being removed, it is possible to speed up the restart of the image forming apparatus.

[0050]

As described above, according to the present invention,
If the transfer material runs out or the transfer material is clogged after the toner image is formed on the intermediate transfer body, hold the toner image on the intermediate transfer body without removing it and transfer it to the re-fed transfer material. You can speed up the restart because it can be.

When the transfer material is not re-fed within a certain time, the toner image on the intermediate transfer member is removed by the cleaning means, so that the transfer roller is contaminated by the toner image and the intermediate transfer member and the image carrier are damaged. Deterioration can be well prevented.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a state in which toner images for two transfer materials are formed on an intermediate transfer member.

FIG. 3 is a flowchart of processing when a paper cut occurs.

FIG. 4 is a flowchart of a process when a paper jam occurs.

FIG. 5 is a vertical cross-sectional view showing a schematic configuration of a conventional image forming apparatus.

[Explanation of symbols]

2 Transfer material 9 Intermediate transfer body 10 Transfer means (transfer roller) 15 Image carrier (photosensitive drum) 40 Cleaning means (cleaning roller)

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-194390 (JP, A) JP-A-5-289440 (JP, A) JP-A-3-39975 (JP, A) JP-A-56- 57051 (JP, A) JP-A-8-11394 (JP, A) JP-A-4-42168 (JP, A) JP-A-5-281803 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 21/00 500 G03G 21/14

Claims (4)

(57) [Claims] 1. An intermediate transfer member carrying a toner image;
Transfer means for transferring the toner image on the intermediate transfer member to a transfer material
To clean the toner image on the intermediate transfer member.
With the leaning means, it is possible to recognize the replenishment of the transfer material.
In the image forming apparatus, the transfer material that transfers the toner image on the intermediate transfer member is the transfer material.
When the toner is not supplied to the copying means, the toner is transferred onto the intermediate transfer member.
Hold the image and hold the toner image on the intermediate transfer member
It takes a certain period of time from when
Toner image on the intermediate transfer member depending on whether or not the time elapses.
Is transferred to the transfer material by the transfer means or the
An image forming apparatus characterized in that it is removed by a burning means or switched . 2. The intermediate transfer member for at least two sheets
The image forming apparatus according to claim 1, wherein the image forming apparatus can carry a toner image to be transferred onto the transfer material . 3. When it is recognized that there is no transfer material,
The image forming apparatus according to claim 1 or 2 , wherein the subsequent supply of the transfer material is recognized . 4. An odor when a transfer material clogging is dealt with.
The image forming apparatus according to claim 1 , wherein the subsequent supply of the transfer material is recognized .