JP2003202715A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device that carries a transfer material while ensuring appropriate linear velocity, without pulling the transfer material between a fixing roller and an inverting roller. <P>SOLUTION: The image forming device has a curved carrying path which leads a transfer material from the fixing part to the roller situated downstream from the fixing part. A transfer material detection sensor having an actuator which projects in the carrying path is disposed near the carrying path. According to a signal from the sensor, the rotational speed of the roller situated in the downstream position is controlled. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus for preventing the transfer material from slipping in the image transfer section and the fixing section as much as possible.

[0002]

2. Description of the Related Art Conventionally, in order to prevent a fixing section roller and a reversing roller positioned downstream of the fixing section from pulling each other, it is necessary to consider the variation in the fixing linear velocity. The linear velocity could not be higher than the minimum fixing linear velocity variation.

In the case of a pulling relationship, the transfer material is squeezed by the rollers, which promotes curling and causes slippage in the transfer material transporting portion, causing contamination of the transfer material. Further, the stepping motor, which is the driving source of the reversing roller, loses synchronism due to an excessive load, which causes a jam.

Further, the fixing linear velocity cannot be set higher than the linear velocity of the transfer portion located upstream thereof, and must be set to be equal to or lower than the basic linear velocity of the transfer portion.

As a result, the linear velocity of the reversing roller is set to be considerably slower than the basic velocity of the transfer section in view of the safety factor, and the linear velocity required for reversing and discharging cannot be set, resulting in deterioration of reliability. It also results in problems such as a decrease in the processing speed of the transfer material.

Further, when the maximum speed of variation of the fixing linear velocity is applied to the transfer material, the linear velocity difference between the fixing portion and the reversing roller becomes large, and a large loop occurs to deteriorate the transfer material conveying performance. Will be lost.

Since the fixing linear velocity varies depending on the usage condition depending on the type and durability of the paper, in order to adjust the reversal linear velocity to the actual fixing linear velocity, the actual linear velocity of the transfer material is accurately measured and adjusted. Although a method of finely adjusting the reversal linear velocity may be considered, the cost becomes expensive and it is not easy to improve the measurement accuracy.

[0008]

Even if there is a variation in the fixing linear velocity, the reversal linear velocity is automatically adjusted in accordance with the fixing linear velocity so that the tension relationship between the fixing roller and the reversing roller can be improved. It is an object of the present invention to provide an image forming apparatus that can convey a transfer material in a state in which an appropriate linear velocity is ensured without making a sheet.

[0009]

This object can be achieved by the following constitution.

(1) A transfer material detecting sensor having a curved conveyance path for guiding the transfer material from the fixing section to a roller located downstream thereof and having an actuator protruding into the conveyance path is provided near the conveyance path. An image forming apparatus (first invention), characterized in that the rotational speed of a roller located downstream of the roller is controlled by a signal from the sensor.

(2) A pair of sensors for detecting the transfer material, which has a curved conveyance path for guiding the transfer material from the fixing section to the roller located downstream of the fixing section, and which has an actuator protruding into the conveyance path. An image forming apparatus characterized in that it is provided in the vicinity of the path, and controls the rotation speed of the roller located downstream according to the signals of the respective sensors (second
Invention).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

In the description of the embodiments of the present invention, the technical scope of the invention is not limited by the terms used in this specification.

FIG. 1 is a schematic diagram showing the overall construction of an electrophotographic image forming apparatus. In the figure, 10 is a photoconductor, 11 is a scorotron charger which is a charging means, 1
2 is a writing device which is an image writing means, 13 is a developing device which is a developing means, 14 is a cleaning device for cleaning the surface of the photoconductor 10, 15 is a cleaning blade, 16 is a developing sleeve, and 20 is an image carrier. 1 illustrates an intermediate transfer belt. The image forming means 1 includes a photoconductor 10, a scorotron charger 11, a developing device 13, a cleaning device 14, and the like. Since the image forming means 1 for each color has the same mechanical structure, Y ( Reference numerals are attached only to the configuration of the (yellow) series, and reference numerals are omitted for the components of M (magenta), C (cyan), and K (black).

The arrangement of the image forming means 1 for each color is in the order of Y, M, C and K with respect to the running direction of the intermediate transfer belt 20, and each photoconductor 10 is a stretched surface of the intermediate transfer belt 20. And is rotated at the contact point in the same direction as the running direction of the intermediate transfer belt 20 and at the same linear velocity.

The intermediate transfer belt 20 includes a driving roller 21, a ground roller 22, a tension roller 23, and a charge eliminating roller 2.
7. The belt unit 3 is stretched around the driven roller 24, and these rollers, the intermediate transfer belt 20, the transfer device 25, the cleaning device 28 and the like constitute the belt unit 3. The traveling of the intermediate transfer belt 20 is performed by rotation of the drive roller 21 by a drive motor (not shown).

The photoconductor 10 is formed by forming a conductive layer, an a-Si layer, or a photosensitive layer such as an organic photoconductor (OPC) on the outer periphery of a cylindrical metal substrate formed of, for example, an aluminum material. Rotate in the counterclockwise direction indicated by the arrow in the figure with the grounded.

An electric signal corresponding to the image data from the reading device 80 is converted into an optical signal by the image forming laser, and the writing device 12 projects the light signal onto the photoconductor 10.

The developing device 13 is formed of a cylindrical non-magnetic stainless steel or aluminum material which keeps a predetermined distance from the peripheral surface of the photoconductor 10 and rotates in the same direction as the rotation direction of the photoconductor 10 in the closest direction. It has a developing sleeve 16.

The intermediate transfer belt 20 has a volume resistivity of 10 ⁶
It is an endless belt of -10 ¹² Ω · cm, and has a conductive material dispersed in engineering plastics such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, and nylon alloy, and has a thickness of 0.1. A seamless belt having a two-layer structure in which a semi-conductive film substrate having a thickness of ˜1.0 mm is coated with fluorine to a thickness of 5 to 50 μm, preferably as a toner filming prevention layer, is provided. In addition to this, a semi-conductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber or urethane rubber can be used as the base of the belt.

Reference numeral 25 denotes a transfer device to which a direct current having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to transfer the toner image formed on the photoconductor 10 to the intermediate transfer belt 20.
It has the function of transferring to the top. As the transfer device 25, a transfer roller may be used instead of the corona discharger.

A transfer roller 26 is an intermediate transfer belt 20.
The toner image formed above is retransferred to the transfer material P.

A cleaning device 28 is provided so as to face the driven roller 24 with the intermediate transfer belt 20 interposed therebetween. After transferring the toner image to the transfer material P, the intermediate transfer belt 20
The charge of the residual toner is weakened by the static elimination roller 27 to which an AC voltage having a DC voltage of the same polarity or the opposite polarity of the toner is applied, and the cleaning blade 29 cleans the toner remaining on the peripheral surface.

A fixing device 40 serving as a heating means has a first fixing roller 41 and a second fixing roller 42 serving as a pressure bonding means.

Reference numeral 5 is a reverse portion of the transfer material. F is a control unit that controls the process of the apparatus. 50 is a reversing roller, 5
1 is an outer R side conveyance guide plate, 52 is an inner R side conveyance guide plate, 53 is a curved conveyance path, 54, 55, 56 and 57 are reverse conveyance paths, 61, 62 and 63 are conveyance rollers, and 65 is sorting. The transfer material P fixed by the fixing device 40 is selected by the valve in the paper discharge direction or the reversing unit 5. 6
6 and 67 are distribution valves. Each distribution valve opens and closes according to a command from the control unit F. Reference numeral 7 denotes a transfer material detection unit (hereinafter referred to as a detection unit).

As will be described later, the present invention relates to a process of controlling the transport speed of the transfer material P transported to the reversing section 5.

Reference numeral 70 is a paper feeding roller, 71 is a timing roller, 72 is a paper cassette, and 73 is a conveying roller.

The image forming process will be described below. Simultaneously with the start of image recording, the photoconductor 10 of the color signal Y is rotated in the counterclockwise direction by the start of a photoconductor drive motor (not shown), and at the same time, a potential is applied to the photoconductor 10 by the charging action of the scorotron charger 11. Is started.

After a potential is applied to the photoconductor 10, the writing device 12 starts writing an image corresponding to the Y image data, and the Y of the original image is printed on the surface of the photoconductor 10.
An electrostatic latent image corresponding to the image is formed.

The electrostatic latent image is reversely developed by the Y developing device 13 in a non-contact state, and Y is developed according to the rotation of the photoconductor 10.
Toner image is formed on the photoconductor 10.

The Y toner image formed on the photoconductor 10 is transferred to the intermediate transfer belt 2 by the action of the Y transfer device 25.
0 is transcribed.

Thereafter, the photoconductor 10 is cleaned by the cleaning device 14 and the next image forming cycle is started (the same applies to the M, C and K cleaning processes, so the description thereof is omitted).

Next, the writing device 12 writes an image corresponding to the M (magenta) color signal, that is, the image data of M, and the M of the original image is formed on the surface of the photoconductor 10.
An electrostatic latent image corresponding to the image is formed. The electrostatic latent image becomes an M toner image on the photoconductor 10 by the M developing device 13, and the intermediate transfer belt 20 is transferred to the M transfer device 25.
It is synchronized with the Y toner image above and is superimposed on the Y toner image.

By the same process, the Y and M superimposed toner images are synchronized with each other, and the C (cyan) toner image is transferred onto the Y and M superimposed toner images at the C transfer device 25. The toner images of K (black) are superposed and synchronized with the superposed toner images of Y, M, and C.
In the K transfer device 25, the superimposed toner images of Y, M, and C are superimposed, and the superimposed toner images of Y, M, C, and K are formed on the intermediate transfer belt 20.

The intermediate transfer belt 20 carrying the superposed toner image is sent in the clockwise direction as shown by the arrow, and the transfer material P is sent out from the paper cassette 72 by the paper sending roller 70, and then through the carrying roller 73, The transfer roller 26 is conveyed to the timing roller 71, and by the driving of the timing roller 71, the transfer roller 26 is synchronized with the superimposed toner image on the intermediate transfer belt 20 and a DC voltage having a polarity opposite to that of the toner is applied to the transfer roller 26. Delivered to area S,
The superimposed toner image on the intermediate transfer belt 20 is the transfer material P.
Is transcribed to.

After that, the intermediate transfer belt 20 travels, the charge of the residual toner is weakened by the discharging roller 27, and the cleaning blade 29 contacting the intermediate transfer belt 20 cleans the intermediate transfer belt 20 to start the next image forming cycle.

Transfer material P on which the superimposed toner images have been transferred
Is further sent to the fixing device 40, and the first fixing roller 41
The transfer material P, which is nipped and conveyed while heat and pressure are applied at the nip portion T between the second fixing roller 42 and the second fixing roller 42, and the superimposed toner image is fused and fixed, is discharged when the distribution valve 65 is in the dotted line. Direction, or in the case of a solid line, it is conveyed in the direction of the reversing unit 5 (reversed paper discharge or double-sided printing).

The present invention will be described below. The present invention relates to a method of appropriately controlling the transport speed of the transfer material P transported to the reversing unit 5 to enable efficient transport.

FIG. 2 is a diagram for explaining a method of detecting the transfer material in the curved conveyance path. In the figure, the detection unit 7
Is a light emitting element 751 (see FIG. 3A) and a light receiving element 75.
2 (see FIG. 3A), which is composed of a sensor (light transmission type switch) 75 and is fixed in the vicinity of the conveyance guide plate 52 on the inner R side. Reference numeral 76 is a shutter that blocks light from the light emitting element 752, and 77 is an actuator that detects the transfer material. The shutter 76 and the actuator 77 are integrally fixed to the rotary shaft 78. The detection unit 7 has a rotating shaft 78.
It is provided substantially at the center of the curved conveyance path 53 in the axial direction of. The rotating shaft 78 is swingably supported by bearings (not shown) near both ends of the shaft. When the transfer material P is not in the curved conveyance path 53, the actuator 77 moves as shown by the dotted line.
The rotation shaft 78 is regulated by a spring and an angle regulation stopper (not shown) so as to protrude from the conveyance guide plate 52 on the inner R side into the conveyance path and reach a predetermined position. However, the spring force (rotational force) is such that the transferred transfer material P can operate the actuator 77.

FIG. 3 is a three-dimensional drawing of the detection unit of FIG. 2, in which (a) is one actuator and (b) is two actuators, showing examples of detecting the transfer material. It is a figure.

First, the embodiment shown in FIG. 3A will be described. Returning to FIG. 2, the transfer material P from the fixing device 40 is distributed by the distribution valve 65 located at the position indicated by the solid line, curved along the curved conveyance path 53, and along the outer R side conveyance guide plate 51. And the sheet is fed to the reversing roller 50 which rotates faster than the fixing linear velocity through the distribution valve 66 located at the position indicated by the dotted line. The transfer material P is the reversing roller 50.
When it is nipped by the transfer material P, the transfer material P whose rear part is nipped by the fixing roller is pulled due to the higher linear velocity,
3A approaches the surface of the side transport guide plate 52, and at the same time, the shutter 76, via the actuator 77, shuts off the light between the light emitting element 751 and the light receiving element 752 of the sensor 75 shown in FIG. At the same time when the sensor 75 is turned on, the signal is sent to the control section F, the rotation speed of the reversing roller 50 is slowed down, and the tension with the fixing roller is avoided.
Furthermore, the transfer material P is conveyed in this slow state, and the transfer material P
When the rear part of is completely released from the nip of the fixing roller,
The transfer material P is conveyed by the waist force of the transfer material itself so as to approach and follow the surface of the conveyance guide plate 51 on the outer R side, and at the same time, the actuator 77 returns to its original state and the sensor 75 is turned off. As a result, the reversing roller 50 returns to the original high linear velocity, and the reversing unit 5 can carry out the conveying process more quickly.

That is, when there is one actuator, the control unit F (see FIG.
The linear velocity of the reversing roller 50 is controlled by the reference.

Next, the embodiment shown in FIG. 3B will be described. In the figure, two sets of actuators projecting from the inner R side transport guide plate are provided, and the detection points of the respective transfer materials P are at two different points between the inner R side and outer R side transport guide plates.

The transfer material P discharged from the fixing device 40 (see FIG. 2) advances along the transport guide plate 51 on the outside R side of the curved transport path 53, and the distribution valve 66 (see FIG. 2) located at the dotted line position. ), Is clamped by the reversing roller 50 (see FIG. 2), is pulled by the reversing roller 50 having a linear velocity higher than the linear velocity of the fixing device 40, and the detection point is near the conveyance guide plate 51 on the outer R side. The actuator 7 against the spring force applied to the rotary shaft 78 by abutting against the 77B.
The shutter 76B integrated with 7B is swung. The oscillated shutter 76B reaches the light-shielding position of the sensor 75B corresponding to the detection point of the transfer material P (close to the outer-R side guide plate 51) (however, at this point, the sensor at the detection point changes from the control unit F). Signal to is blocked). Then, the transfer material P
Contacts the actuator 77A and pushes it down, and at the same time when it reaches a detection point near the inner R side guide plate 52, an integral shutter 76A shields the sensor 75A from light. For the first time, the sensor 75A operates and the control unit F
The linear velocity of the reversing conveyance roller 50 (see FIG. 2) which is rotating slightly faster than the fixing linear velocity is automatically adjusted to be slower than the fixing linear velocity.

However, at this time, the linear velocity of the reversing roller 50 is slightly lower than the linear velocity of the fixing, so that a loop is generated in the transfer material P whose rear portion is sandwiched by the fixing device 40 (see FIG. 2) and the actuator is actuated. 77B and 77A are restored to the original state, and are conveyed along the surface of the conveyance guide plate 51 on the outer R side, and at the same time, the sensor 76B is turned on only after the light shielding is released, and the reversing roller is passed through the control unit F. 50 is returned to the original high linear velocity, and the conveyance process can be performed more quickly in the reversing unit 5 (when the sensor 75A is released from light blocking, the signal to the control unit F is cut off).
Next, the transfer material P having a high speed is pulled by the reversing roller 50 to push down the actuator 77A again, the shutter 76A shuts off the sensor 75A, and the linear speed of the reversing roller 50 is reduced.

Next, the rear end of the transfer material P is fixed to the fixing device 4.
When the transfer material P is discharged from 0, the transfer material P is brought into a state along the outer R side conveyance guide plate 51, the actuator 77B operates, and the reversing roller 50 is accelerated.

In the embodiment shown in FIG. 3B, even when the transfer material P is conveyed from the fixing device 40, the linear velocity of the reversing roller 50 is unnecessarily increased by turning the actuators 77A and 77B on and off. It is not set to be low to reduce the processing speed of the transfer material, the reliability is not deteriorated, and the transfer material transportability is not deteriorated due to the excessive loop.

Returning to FIG. 1, the transfer material P that has passed through the detection portion 7 is further nipped and conveyed by the reversing roller 50, and in the case of reverse ejection, the rear end portion in the conveying direction passes through the sorting valve 66. , The predetermined position of the transfer material P is still sandwiched by the reversing roller 50, the reversing roller 50 is temporarily stopped and then reversely rotated, and the distribution valve 66 becomes a solid line state.
The rear end portion of the transfer material P becomes the front end portion and is directed upward, and is ejected to the paper ejection tray 82 by the paper ejection roller 81.

In the case of double-sided printing, the reversing roller 50
The transfer material P sent by
After passing through the sorting valve 67 in a solid line, the sheet is nipped and transported by the transport roller 61, and the rear end of the transfer material passes through the sorting valve 67,
With the predetermined position of the transfer material P being held between the transfer rollers 61, the transfer roller 61 is temporarily stopped and then reversely rotated, and the sorting valve 67 is in the state of a dotted line. The end portion serves as the leading end portion and is conveyed to the reversing conveyance path 56, and is nipped and conveyed by the conveyance rollers 62, and the reversal conveyance path 57.
After that, it is nipped and conveyed by the conveyance roller 63 and reaches the timing roller 71. Here, while forming a loop, it is synchronized with the toner image on the intermediate transfer belt 20, is conveyed to the transfer area S by the re-movement of the timing roller 71, is transferred by the transfer roller 26, and advances to the fixing device 40.

[0050]

Even if the fixing linear velocity varies,
By automatically adjusting the reversal linear velocity according to the fixing linear velocity, the transfer material can be conveyed in a state in which a proper linear velocity is secured without creating a tension relationship between the fixing roller and the reversing roller. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic view showing an overall configuration of an electrophotographic image forming apparatus.

FIG. 2 is a diagram for explaining a method of detecting a transfer material in a curved conveyance path.

FIG. 3 is a three-dimensional drawing of the detection unit of FIG.
FIG. 4A is a diagram showing an example in which a transfer material is detected by one actuator and FIG.

[Explanation of symbols]

1 Image forming means 10 photoconductor 12 Writing device 20 Intermediate transfer belt 25 transfer device 26 Transfer roller 3 Belt unit 52 Reverse roller 51 Transport guide plate on outer R side 52 Transport guide plate on inner R side 65, 66, 67 distribution valve 7 Detector 75 sensor 77 Actuator

Continued front page    (72) Inventor Kazunori Katata             2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock             In the company F-term (reference) 2H027 DA20 DC05 DE03 DE07 DE10                       ED16 EE03 EF09                 2H028 BA06 BA09 BA16                 2H072 AA03 AA16 AA17 AA24 CA01                       CB06                 3F049 AA02 DA12 EA10 EA22 LA02                       LB03                 3F053 BA03 BA14 BA19 BA29 LA01                       LB03

Claims (6)

[Claims] 1. A transfer material detecting sensor having a curved conveyance path for guiding a transfer material from a fixing section to a roller located downstream of the fixing section and having an actuator protruding into the conveyance path is provided near the conveyance path. An image forming apparatus provided, wherein the rotation speed of a roller located downstream is controlled by a signal from the sensor. 2. The actuator projects into the conveyance path more than the conveyance guide plate on the inner R side of the conveyance path, and the transfer material detection point is between the conveyance guide plates on the inner R side and the outer R side. The image forming apparatus according to claim 1. 3. When the sensor detects the transfer material, the rotation speed of the roller located downstream is decreased, and when the sensor stops detecting the transfer material, the rotation speed is returned to the original value, or
Alternatively, the image forming apparatus according to claim 2, wherein the speed is increased. 4. A pair of transfer material detecting sensors, each having a curved conveyance path for guiding the transfer material from a fixing section to a roller located downstream of the fixing section, and having an actuator protruding into the conveyance path. An image forming apparatus provided in the vicinity of the image forming apparatus, wherein the rotation speed of a roller located downstream is controlled by signals from respective sensors. 5. The actuator protrudes into the conveyance path more than the conveyance guide plate on the inner R side of the conveyance path, and its transfer material detection point is different between the conveyance guide plates on the inner R side and the outer R side. The image forming apparatus according to claim 4, wherein there are two points. 6. When one of the two sets of sensors whose detection point is near the inner R side conveyance guide plate detects the transfer material, the rotation speed of the roller located downstream is slowed down, and the detection point is the outer R side.
The image forming apparatus according to claim 5, wherein when the sensor near the side transport guide plate no longer detects the transfer material, the rotation speed of the roller is returned to the original speed or is increased.