JPH0258082A - Image forming device - Google Patents

Abstract

PURPOSE:To miniaturize the title device and to transfer fine picture quality by forming an image on media to be transferred while the media to be transferred is adsorbed from the sucking port of a rotating body provided corresponding to the position of the cover of one side of the media to be transferred. CONSTITUTION:A transfer drum 11 is wound by a copy paper P which is taken out from a paper feeding cassette and held by a gripper 13. A vacuum chamber 90 is provided at the right hand in the figure inside of this drum 11 to lower the atmospheric pressure inside of the drum. Besides, the drum 11 is provided with the sucking port 91 which adsorbs the copy paper P held by the gripper 13 on the surface of the drum of the vacuum chamber 90. An L-type breather is connected to a blower 92 at the right hand in the figure of the drum 11. Inside of this blower 92 is provided with a motor, and by rotating fan caused by the rotating drive of this motor, air is attracted from the sucking port 91 of the drum 11 and exhausted from an arrow. When the atmospheric pressure inside of the vacuum chamber 90 by exhausting air, the trailing edge of the paper P held by the gripper 13 is adsorbed from the sucking port 91.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides an image forming apparatus that is provided with a rotating body that wraps around and holds a transfer medium, and forms an image on the transfer medium. Regarding.

(Prior Art) Conventionally, among image forming apparatuses, for example, an apparatus disclosed in Japanese Patent Publication No. 59-26023 is known as an example of image forming using a color copying machine.

In other words, a signal read from a document reading unit (not shown) is irradiated onto a pre-charged photoreceptor drum by a mirror or the like to form an electrostatic latent image, which causes the current device containing toner of each color to be illuminated. The toner is adsorbed onto the photoreceptor drum from the first
The color is visualized.

The transfer drum, which is in contact with the photoreceptor drum forming this visualized toner image, holds the copy paper in a gripper.
The toner image on the photoreceptor drum is transferred onto copy paper by holding the photoreceptor drum and rotating it while facing the photoreceptor drum. After the transfer of the first color is completed, the photoreceptor drum and the transfer drum rotate in the same manner while facing each other, and the toner image of the second color is transferred onto the copy paper on the transfer drum so as to overlap with each other. , and the third and fourth colors are similarly repeated.

When the transfer of the fourth color is completed, the copy paper is fixed and discharged to the collection tray.

(Problems to be Solved by the Invention) Conventionally, in order to downsize the apparatus, the diameter of the transfer drum must be smaller than a predetermined diameter, for example, 150 ml. However, if the diameter of the transfer drum is made smaller than the above-mentioned 1501, the rear end of the copy paper wrapped around the drum in the opposite direction from the clipper due to the stiffness of the copy paper held by the gripper of the transfer drum. There was a risk that the image would become separated from the transfer drum, making it impossible to obtain a clear image.

The present invention has been made in view of the above, and an object thereof is to provide an image forming apparatus that can transfer clear image quality even when the apparatus is downsized.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a rotating body that rotates while forming an image on the transfer medium while wrapping and holding the transfer medium. and a suction port provided on the rotary body at a position corresponding to one end of the surface of the transfer medium for the transfer medium of various sizes that are held by being wound around the rotating body. and a suction means for sucking the transfer medium wound around the rotary body from the suction port onto the rotary body.

(Function) In the image forming apparatus having the above configuration, suction is provided at a position corresponding to one end of the surface of the transfer medium of various sizes, which is held by being wrapped around a rotating body during the transfer of both images. The transfer medium is attracted through the mouth, for example, the inside of the rotating body is brought into a vacuum state. When it is in a vacuum state, the transfer medium held around the rotating body of the suction port is held by suction, and an image is formed on the transfer medium by holding the transfer medium on the rotating body, resulting in clear image quality. images can be obtained.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic diagram showing the internal structure of an embodiment of the image forming apparatus of the present invention applied to, for example, a color copying machine. This image forming apparatus includes a document reading device (not shown) and a recording device 1.

The document reading device separates the image information of the read document into dots and sequentially outputs the image information obtained for each color component to the recording device 1. The recording device 1 sequentially irradiates image information for each color component onto a photoreceptor drum 5 with a laser beam 2 via a mirror of an exposure optical system 3, etc., to form a latent image. The photosensitive drum 5 adsorbs the first color toner from the developing device 9A, visualizes the latent image formed by the laser beam 2, and forms a toner image.

On the other hand, a gripper 13 provided on the transfer drum 11 grips a copy paper (transfer medium) P stored in a paper feed cassette 17, and the copy paper P is attached to the outer periphery of the transfer drum 11. This transfer drum 11 and photosensitive drum 5
and are opposed to each other while maintaining contact at the transfer position 51C,
Arrow E respectively.

The first color toner image on the photoconductor drum 5 is transferred to the copy paper P by rotating at a constant speed in the E direction.Also, while the photoconductor drum 5 is also rotating in the E direction, the initial position is the transfer position 51C. In this way, the second, third, and fourth color dog images are sequentially transferred onto the copy paper P, and when the transfer is completed, After the copy paper P is released from the transfer drum 11 , it is fixed by the fixing device 21 and discharged onto the collection tray 23 .

The exposure optical system 3 is connected to the printer main body 1 which is the storage device 1 mentioned above.
A high-speed rotating motor 27 and a polyhedral rotating mirror 29. fθ lens 312 reflection mirror 33.35. Aspheric lens 37. A protective glass 39 is provided. A laser beam 2 oscillated from a semiconductor laser #j'' (not shown) is input into the exposure optical system 3 after being shaped by a beam shaping optical system (not shown) comprising, for example, a cylindrical lens. Further, the laser beam 2 is transmitted to a drive controller 41 adjacent to the exposure optical system 3 in the upper part of the printer main body 1.
The beam is deflected by a polyhedral rotating mirror 29 that is rotationally driven by a high-speed rotating motor 27 using an air bearing that is drive-controlled. The deflected laser beam 2 passes through the fθ lens 31, is reflected by the mirrors 33 and 35, and passes through the aspherical lens 37 and the protective glass 39 to form a spot with the necessary resolution at the exposure position 51A on the photoreceptor drum 5. The image is scanned and exposed.

Around the photosensitive drum 5, there is a charger 43 for charging the drum surface. A developing device support 7 equipped with developing devices for each color, and a rotating transfer drum 11 with copy paper attached to the drum surface. Cleaner 53. An erasure/discharge lamp 55 is provided. The photosensitive drum 5 is rotated at an outer circumferential speed by a pulse motor 79, which will be described later, to drive the grid electrode 45.
The drum surface is charged by a charging charger 43 provided opposite to the drum surface. The photosensitive drum 5, on which the laser beam 2 is spot-imaged via the protection mirror 39 at the exposure position 51A on the drum surface of the charged photosensitive drum 5, rotates in the direction of arrow E to the developing position 51B. Then, the developing sleeve 4 of the developing device 9A contacts the developing device 9A of the developing device support 7 and the spot image is formed.
Yellow toner is supplied to the drum 5 from 9A and is absorbed.

A cylindrical developing device support body 7 housing this developing device 9A
, there is a developing device 9B having a developing sleeve 49t3 storing magenta toner at the side of the developing device 9A, a developing device 9C having a developing sleeve 49C storing cyan 1 hener, and a developing device 9C having a developing sleeve 49C storing black toner. Developing devices 9D each having a developing sleeve 49D are provided adjacent to each other.

The developing device support 7 is rotated in the direction of arrow G by a process drive system 81 (described later) about a central axis 47, and the developing device support 7 is rotated in the direction of arrow G by a process drive system 81, which will be described later. 9A to 9D are sequentially moved to the developing position 51B of the photosensitive drum 5. For example, a developed image formed with the first color yellow toner is transferred to the copy paper P attached to the transfer drum 11 at the transfer position 51G of the photoreceptor drum 5, but only after the transfer is completed. Until the transfer of the second color starts, the developing device support 7 rotates in the direction of arrow G, and the developing device 9B for magenta, the second color, moves to the developing position 51B on the photoreceptor drum 5.

The photoreceptor drum 5, on which a phenomenon image has been formed by adsorbing toner of one color in the developing device, continues to rotate and transfers the toner onto the copy paper 1 which has been deposited on the transfer drum 11 at the transfer position 51C. Transfer the visualized toner image. After the transfer at the transfer position 51C, the photoreceptor drum 5 continues to rotate in the direction of arrow E, and the residual toner adhering to the surface of the drum is removed by the cleaner 53 provided opposite to the photoreceptor drum 5. Then, the remaining potential on the surface of the drum is removed by the erasing charge removing lamp 55.

The transfer drum 11 includes a gripper 13 fixedly provided on a part of the drum surface for holding the copy paper P, and a gripper 13 for holding the copy paper P fed by the paper feed roller 19. It is equipped with a sensor 15 for detection. This transfer drum 11 is driven by a pulse motor 7, which will be described later.
While the toner image on the photoreceptor drum 5 is transferred onto the copy paper P by the rotational drive of the photoreceptor drum 9, the photoreceptor drum 5 rotates in the direction of the arrow F at an outer circumferential speed equal to that of the photoreceptor drum 5. In addition to the photosensitive drum 5, a paper feed roller 19/jar 59 and a movable guide plate 61 are arranged around the transfer drum 11.

The surface of the transfer drum 11 is charged by a charger 59 provided opposite to the drum 11.
The copy sheets P stored in the paper feed cassette 17 are fed one by one by the rotation of the paper feed roller 19. When the copy paper P is supplied, a gripper 13 provided at the end of the transfer drum 11 holds the leading edge of the copy paper P, and the copy paper P is attached to the transfer drum 11 by the charge of the blow jar 59. Copy paper P is gripper
When the copy paper P is held by the drum 13, a sensor 15 provided at the end of the drum detects that the copy paper P is held and outputs a detection signal to a control device 75, which will be described later. Copy paper P
The transfer drum 11 to which the photoreceptor drum 5 is attached rotates at the same speed as the photoreceptor drum 5 and transfers the toner image formed on the photoreceptor drum 5 onto the bead paper P. When the rear end of the copy paper P passes the transfer position 51C of the photosensitive drum 5 and the transfer is completed, one end is fixed and the other end is in contact with the surface of the drum 11 or at a position several centimeters away from the surface of the drum 11, for example. (61
The movable guide plate 61, which is interlocked with a) by a signal from the control device 75, moves in the direction 61b and comes into contact with the transfer drum 11. Upon contacting the drum 11, the copy paper P passes through the movable guide plate 61 and is conveyed to a heat roller 63 and a pressure roller 65, which are provided in the fixing device 21 provided near the movable guide plate 61. After the toner image of the conveyed copy paper P is fixed on the copy paper P by the heat roller 63 and the pressure roller 65, the copy paper P is roughly transferred to the paper discharge roller 67.
69 and discharged onto the collection tray 23.

The cooling fan 71 cools waste heat discharged from the heat roller 63, pressure roller 65, etc. of the fixing device 21, and prevents the temperature inside the printer body 1 from becoming high.

FIG. 2 is a block diagram for controlling the internal structure of the image forming apparatus described in FIG. 1. In the figure, the control device 7
Reference numeral 5 has a CPU (central processing unit) that performs various controls and calculations, and is arranged in the controller 25. The sensor 15 is provided at the end of the transfer drum 11, and when it detects that the gripper 13 holds the leading edge of the copy paper P, it outputs a detection signal to the control device 75. The laser oscillator 76 outputs laser light according to image information from a page memory 85, which will be described later. The pulse motor 79 rotates in response to the number of pulses output from the control device 75, and rotates in response to the number of pulses output from the control device 75. The transfer drums 11 are each driven to rotate.

For example, if the timing for writing one color of toner from the developer onto the copy paper P is set to 5000 pulses, the writing timing for the first color is 0 pulse, the writing timing for the second color is 5000 pulses, and the timing for writing the second color is 5000 pulses. The timing to capture the third color is controlled at the 10,000th pulse.

In this way, since the writing timing is controlled in response to the number of pulses, color shift during transfer can be prevented. Note that this pulse motor 79 can be driven to rotate arbitrarily depending on the number of pulses output from the control device 75.

The process drive system 81 controls a semiconductor laser (not shown), a charging charge 43 . A drive signal is output to the developing device support 7 and the like to control the drive.

When an image signal obtained by reading an image written on an object to be read is input to the control device 75 from the document reading section (not shown), the page memory 85 is configured to input a predetermined "I address" for each color component by the control device 75. The image signal is stored in the .

FIG. 3 is a view showing the suction port and suction means of the present invention, and is a view showing a state in which the copy paper P is wrapped around the gripper 13 of the transfer drum 11 shown in FIG.

The copy paper P taken out from the paper feed cassette 17 is held and wound around the transfer drum 11 by a gripper 13 . A vacuum chamber 90 is provided inside the transfer drum 11 on the right side in the figure to reduce the air pressure inside the drum.

Further, the transfer drum 11 is provided with a suction port 91 for sucking the copy paper P held by the gripper 13 on the drum surface of the vacuum chamber 90. This suction port 9
1 is located on one side of the copy paper P held by the gripper 13, at the right corner in the figure.

The reason why the suction port 91 is provided in one corner of the copy paper P instead of in the transfer area is because if the suction port 91 is provided in the transfer area of the copy paper P, the image quality of the transferred image will deteriorate. This is because of that. Furthermore, the number of suction ports 91 is greater than the number of copy paper sheets P held on the transfer drum 11.
It is determined by the type of For example, A4 version, A3
If you are picking up copy paper P for the 85th and 84th editions, use 4.
It has several suction ports 91.

The right end of the transfer drum 11 in the figure is connected to a blower 92 via an L-shaped vent. The blower 92 has a motor therein, and the rotation of the motor rotates the fan, which sucks air through the suction port 91 of the transfer drum 11 and exhausts it in the direction indicated by the arrow. As the air is exhausted and the pressure in the vacuum chamber 90 decreases, the rear end of the copy paper P held by the gripper 13 is attracted to the suction port 91 . The trailing edge of the copy paper P is attracted to the suction port 91 and is transferred while being wrapped around the transfer drum 11, so even if the diameter of the transfer drum 11 is reduced as the device becomes smaller, the copy paper P remains It is possible to prevent image quality from deteriorating due to so-called stiffness.

Note that the blower 92 is capable of emitting enough exhaust air to attract the copy paper P to the drum 11, so it may be small.

FIG. 4 is a sectional view of the transfer drum 11 of FIG. 3. The vacuum chamber 90 described above is provided on the right side of the transfer drum 11 in the figure, and the vacuum chamber 90 is provided with a suction port 91 on the drum surface. A partition wall 93 is provided to partition the vacuum chamber 90. On the other hand, a timing pulley 94 connected to the right end of the transfer drum 11 in the figure is rotated by the process drive system 81 to rotate the transfer drum 11 . A duct 95 adjacent to this timing pulley 94 exhausts air from the vacuum chamber 90 of the transfer drum 11.
is provided. Due to the exhaust from the duct 95, the suction port 91 of the transfer drum 11 absorbs air, and the copy paper P held wound around the transfer drum 11 is attracted. The timing pulley 94 and duct 95
are connected in a straight line and are fixed by a bearing 96a that fixes the transfer drum 11. Further, the left side of the transfer drum 11 in the figure is also fixed by a bearing 96b in order to fix the transfer drum 11 to the shaft 97b.

Next, the operation of this embodiment will be explained using the processing flowchart shown in FIG.

First, the system starts up when the power switch of the device is turned on. When the copy switch is pressed after specifying the input of the paper feed cassette 17, copy paper size, transfer density, etc., the device starts reading the original placed in the original reading section (not shown). . The image information of the document read by the document reading section is separated into each color component and sent to the control device 75 (step '100).

When the copy switch is pressed, the control device 75 outputs a pulse signal to the process drive system 81 to drive the blower 92 and exhaust air from the suction port 91 to the duct 95. While the blower 92 is being driven, the transfer drum 11 continues to rotate, and when the gripper 13 approaches the paper feed roller 19, the paper feed roller 19 removes one sheet of copy paper P stored in the paper feed cassette 17. taken out. The copy paper P taken out by the paper feed roller 19 is held by the gripper 13 and wound around the drum surface. When the copy paper P is wound, the control device 75 closes the gripper 13, rotates the transfer drum 11 to the transfer position 51C of the photosensitive drum 5, and enters a transfer waiting state (steps 110 to 160).
).

When the trailing edge of the copy paper P held by the gripper 13 is attracted to the suction port 91 and wound around the transfer drum 11, the process proceeds to step 18.0, and the trailing edge of the copy paper P is sufficiently wrapped around the transfer drum 11. If it is not adsorbed, the process returns to step 110 (step 170).

When proceeding to step 180, the gripper 1 of the transfer drum 11
When the bee paper P approaches the transfer position 51C of the photosensitive drum 5, the control device 75 outputs a pulse signal to the pulse motor 79. The pulse motor 79 rotates in response to a pulse signal from the control device 75, so that the transfer drum 11 rotates at an outer circumferential speed that is the same as that of the photosensitive drum 5.

The toner image on the photosensitive drum 5 is transferred onto the copy paper P on the transfer drum 11 by rotating the photosensitive drum 5 and the transfer drum 11 while maintaining a contact state. In this way, when the transfer of the first color onto the copy paper P is completed, the transfer drum 11 rotates to the transfer position 57A where the second color is transferred.

On the other hand, after the photosensitive drum 5 has been transferred to the transfer drum 11, a cleaner 53 removes the toner adhering to the surface, and an erasing and neutralizing lamp 55 eliminates static electricity from the surface of the drum. By repeating these operations for each color, the developing device 9
Full-color transfer by overlapping transfer using toner of each of the four colors from the yellow developing sleeve 49A of Δ to the black developing sleeve 49D of the developing device 9D is completed. When the full-color transfer is completed, the control device 75 outputs a drive signal to the wrestling drive system 81 to move the movable guide plate 61 from a point 61a approximately 2 to 3 mm away from the transfer drum 11.
It rotates to point b and fuses to the transfer drum 11. The transferred copy paper P is transferred to the fixing device 21 by the movable guide plate 61.
The toner image is fixed by a heat roller 63 and a pressure roller 65, and is discharged onto the collecting tray 23 by IJI paper rollers 67 and 69.

As a result, the rear end of the copy paper P held by the gripper 13 of the transfer drum 11 prevents the toner image from shifting on the surface of the drum 11 due to the stiffness of the copy paper P, thereby reducing the size of the apparatus. Clear images can be obtained even if the diameter of the transfer drum 11 is reduced accordingly.

In this embodiment, only the blower 92 and the like are provided, so the apparatus does not become complicated.

Furthermore, this embodiment is not limited to application to color copying machines, but can also be applied to, for example, facsimiles, monochrome copying machines, etc. that read and transfer documents.

[Effects of the Invention] As explained above, according to the present invention, the transfer medium is sucked from the suction port of the rotating body provided corresponding to the position of one corner of the transfer medium while the transfer medium is being sucked. Since the image is formed on the image, clear image quality can be transferred even if the device is miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the internal structure of an apparatus showing an embodiment of the present invention, FIG. 2 is a block diagram showing control of the image forming apparatus shown in FIG. 1, and FIG. 3 is a configuration diagram showing a transfer drum. FIG. 4 is a sectional view of the transfer drum of FIG. 3, and FIG. 5 is a flowchart showing the operation of the present invention. 5... Photosensitive drum 9A to 9D... Phenomenon 11
... Transfer drum 75 ... Control device 81 ... Process drive system 91 ... Suction port 95 ... Duct 13 ... Gripper 79 ... Pulse motor 90 ... Vacuum chamber 92 ...・Blower

Claims (1)

[Scope of Claims] A rotating body that rotates while forming an image on the transfer medium while wrapping and holding the transfer medium, and the various sizes held while being wound around the rotating body. A suction port is provided on the rotating body at a position corresponding to one end of the surface of the transfer medium, and the transfer medium wrapped around the rotating body is rotated from the suction port. An image forming apparatus comprising: an adsorption means that adsorbs to a body.