JP2002333754A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that control is complicated and the stability of actuation is lowered because image forming speed must be switched in the case of switching fixing speed though the fixing speed must be made low in an image forming stage where an image is formed on cardboard, glossy paper and an OHP sheet, and a problem that a device gets larger if the image forming speed is not made low. SOLUTION: The fixing speed is switched and also transfer speed is switched, but the image forming speed is kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to an image forming apparatus that forms an image on a recording material by an electrophotographic method used as a facsimile or the like, and more particularly, to control of an image forming apparatus accompanying switching of an operation mode of a fixing device.

[0002]

2. Description of the Related Art An electrophotographic image forming apparatus is used not only for forming an image on a normal paper as a recording material but also for forming an image on a thick paper or an OHP sheet. Further, as the image forming mode, an image is formed in a gloss mode in which a glossy image is formed in addition to the normal image forming. In the present specification, ordinary paper refers to paper called plain paper or plain paper having a thickness used for ordinary office work and books.

In order to cope with such a difference in the type of recording material and an image forming mode, a fixing process is changed. That is, when a toner image is fixed on thick paper, a larger amount of heat energy is applied to the recording material than that of normal paper. Also, when an OHP sheet is used or when a glossy image is formed, it is necessary to increase the transparency of the image or to apply a larger amount of heat energy to the recording material than usual in order to increase the glossiness, thereby increasing the melting degree of the toner. That is being done.

As described above, as a means for applying a large amount of thermal energy to a recording material, it is widely practiced to reduce the conveying speed of the recording material in the fixing means, and without increasing the power consumption of the image forming apparatus. Is achieved.

[0005]

In the image forming apparatus,
Since the conveying speed of the recording material needs to match the moving speed of the image forming body such as the photoreceptor and the intermediate transfer body in the image forming process, and the moving speed of the image carrier, as described above in many image forming apparatuses, When the transport speed of the recording material in the fixing unit is reduced, control is performed to reduce the moving speed of the photosensitive member or the intermediate transfer body in accordance with the reduction in the transport speed of the recording material.

In some image forming apparatuses, the moving speed of the photosensitive member or the intermediate transfer member is not changed with respect to the change of the conveying speed of the recording material in the fixing means. The difference between the transport speed of the recording material at the transfer position and the transport speed of the recording material at the fixing position is absorbed by the configuration in which the distance between the transfer position and the fixing position is longer than the length of the recording material.

In a configuration in which the moving speed of the photosensitive member or the intermediate transfer member is changed in accordance with the fixing unit, it is necessary to correct the characteristics of the image forming unit which fluctuate due to the change in the moving speed of the photosensitive member or the intermediate transfer member. However, there is a problem that the stability is lowered as well as complexity.

In the configuration in which the distance between the transfer position and the fixing position is longer than the length of the recording material, there is a problem that the apparatus becomes large.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem in an image forming apparatus for changing a conveying speed of a recording material in a fixing unit.

[0010]

The above-mentioned object of the present invention is achieved by the following inventions.

1. An image carrier, an image forming body, an image forming means for forming a single color image on the image forming body, and a plurality of primary transfer means for transferring a single color image on the image forming body to the image carrying body. Single-color image forming unit,
An image forming apparatus including: a secondary transfer unit that transfers a multicolor image formed by the single color images transferred from the plurality of single color image forming units to a recording material; and a fixing unit that fixes the multicolor image on the recording material. A first mode in which an image is formed by matching the fixing speed of the fixing unit with the image forming speed of the single-color image forming section; and a second mode in which the fixing speed is different from the image forming speed to form an image. And in the second mode, moving the image carrier at the image forming speed at least until the image carrier is transferred to the image carrier of a single-color image by the primary transfer unit, An image forming apparatus, wherein after the transfer of a monochromatic image to the image carrier is completed, the image carrier is moved at the fixing speed to perform the transfer by the secondary transfer unit.

2. The image forming in the plurality of single-color image forming units is performed at the image forming speed maintained unchanged with respect to the change in the fixing speed.
4. The image forming apparatus according to claim 1.

3. In the second mode, the transfer by the secondary transfer unit is performed after the image carrier has moved a distance equal to or longer than the length of the recording material from the primary transfer unit that is the most downstream in the movement direction. 3. The image forming apparatus according to 1 or 2 above, wherein

4. In the second mode, after the image carrier makes one or more rounds from the last transfer of the monochrome image,
The image forming apparatus according to any one of claims 1 to 3, wherein a multicolor image is transferred by the secondary transfer unit.

[0015] 5. 5. The image forming apparatus according to claim 1, wherein in the second mode, the fixing speed is set to a value lower than the image forming speed.

6. Cleaning means for cleaning the image carrier after transfer by the secondary transfer means,
5. The image forming apparatus according to claim 4, wherein the cleaning unit is retracted at least when an image passes in a moving step in which the image carrier makes one round.

[7] 7. The image forming apparatus according to 4 or 6, wherein the secondary transfer unit is set to a non-operating state at least when an image passes in a moving step in which the image carrier makes one round.

[8] 8. The image forming apparatus according to 4, 6, or 7, wherein the primary transfer unit is set to a non-operating state at least when an image passes in a moving step in which the image carrier makes one round. apparatus.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color image forming apparatus as an example of an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG.

The image forming apparatus is referred to as a tandem type color image forming apparatus.
Y, 10M, 10C, and 10K, a belt-shaped intermediate transfer body 6 as an image carrier, a sheet feeding and conveying unit 30, and a fixing unit 2.
4 is provided.

The yellow image forming section 10Y includes a photoreceptor 1Y as an image forming body and image forming means disposed therearound, that is, a charging means 2Y, an exposing means 3Y, and a developing means 4
Y, a primary transfer unit 7Y and a cleaning unit 8Y. The magenta image forming unit 10M includes a photoreceptor 1M as an image forming body and image forming units disposed therearound, that is, a charging unit 2M, an exposing unit 3M, a developing unit 4M, a primary transfer unit 7M, and a cleaning unit 8M. And The cyan image forming unit 10C includes a photoconductor 1C as an image forming body.
And image forming means disposed therearound, that is, charging means 2C, exposure means 3C, developing means 4C, and primary transfer means 7.
C and cleaning means 8C. The black image forming unit 10K includes a photoreceptor 1K as an image forming body and image forming units disposed therearound, that is, a charging unit 2K, an exposing unit 3K, a developing unit 4K, a primary transfer unit 7K, and a cleaning unit 8K. And The exposing units 3Y, 3M, 3C and 3K expose the photoconductors 1Y, 1M, 1C and 1K based on monochromatic image information of yellow, magenta, cyan and black. The developing units 4Y, 4M, 4C, and 4K contain yellow toner, magenta toner, cyan toner, and black toner, respectively, and form a monochromatic image of each color by development.

The intermediate transfer member 6 includes a plurality of rollers 9A, 9
B, 7Y, 7M, 7C and 7K are stretched and circulate as indicated by arrows.

The monochrome image forming units 10Y, 10M, 10C,
The image formation at 10K is performed with timing control so that one multicolor image is formed on the intermediate transfer body 6.
As shown by the arrows, the primary transfer means 7Y, 7M, 7C, and 7K sequentially transfer (primary transfer) the intermediate transfer member 6 that circulates to form a full-color image, that is, a multicolor image. You. The recording material P accommodated in the paper feed cassette 20 is fed by a paper feed unit 21,
The multicolor image is conveyed to the secondary transfer means 7A via the registration rollers 23A and 22B and is transferred onto the recording material P (secondary transfer). The recording material P to which the multicolor image has been transferred is subjected to a fixing process by a fixing unit 24, conveyed by a discharge roller 25, and placed on a discharge tray 26 outside the apparatus.

On the other hand, after the multicolor image is transferred onto the recording material P by the secondary transfer means 7A, the residual toner is removed from the intermediate transfer member 6 from which the recording material P has been separated by the cleaning means 8A.

In this embodiment, the image forming body is an OP.
Although the C photoconductor is used, an OPC photoconductor or an aSi photoconductor can be used. As the charging means 2Y, 2M, 2C and 2K, a scorotron charging device is used in the present embodiment, but a contact type charging device such as a scorotron charging device, a corotron charging device, and a charging roller can be used. In this embodiment, a laser exposure device is used as the exposure means 3Y, 3M, 3C, and 3K, but a laser exposure device or a light emitting diode array using a laser diode as a light source and a rotating polygon mirror as a scanning means is used. An exposure device can be used. Developing means 4Y, 4M, 4C and 4
In the present embodiment, the developing device of the two-component system, the reversal developing system, and the contact developing system is used as K, but any of the two-component developing system and the one-component developing system may be used. Any type of developing device may be used. Further, either a contact developing method or a non-contact developing method may be used.

In the present embodiment, the primary transfer means 7Y, 7M, 7C, 7K and the secondary transfer means 7A use a roller transfer method in which transfer is performed by a roller to which a transfer voltage is applied. Either a transfer method or a corona transfer method may be used.

Cleaning means 8A, 8Y, 8M, 8C
In this embodiment, a blade cleaning device having a cleaning blade 81A is used as the cleaning device 8K and the cleaning device 8K, but any of a blade cleaning system and a brush cleaning system may be used.

As the fixing means 24, in this embodiment, a heat roller fixing device having a heating roller 24A and a pressure roller 24B having a heat source 24C therein is used, but other contact type such as a belt fixing device is used. A fixing device may be used.

In this embodiment, the length L of the conveying path between the secondary transfer means 7A and the fixing means 24 is shorter than the length of the recording material P in order to reduce the size of the apparatus. . The sheet cassette 20 can store recording materials of various sizes. In the present embodiment, the length L of the conveyance path is shorter than the maximum length of the recording material P in the conveyance direction.

Therefore, in the present embodiment, a state occurs in which the recording material P straddles the secondary transfer means 7A and the fixing means 24 in the image forming process.

The image forming process is performed as follows. Charge, exposure, and development are performed on the photoconductor 1Y by rotation of the photoconductor 1Y indicated by an arrow, and a yellow toner image is formed on the photoconductor 1Y. Similarly, a magenta toner image, a cyan toner image, and a black toner image are formed on the photoconductors 1M, 1C, and 1K, and the monochromatic images are transferred to the intermediate transfer body 6 by the primary transfer units 7Y, 7M, 7C, and 7K. As a result, a multicolor image is formed on the intermediate transfer member 6.

The intermediate transfer member 6 circulates as shown by the arrow,
The multicolor image on the intermediate transfer body 6 is transferred to the recording material P supplied from the sheet cassette 20 by the secondary transfer unit.

The recording material P on which the multicolor image has been transferred is fixed by the fixing means 2
4, the sheet is subjected to a fixing process, and is discharged to a sheet discharge tray 26 by a sheet discharge roller 25.

In this embodiment, an image can be formed on thick paper, glossy paper, OHP sheet, or the like, other than ordinary paper, as the recording material P. In the first mode, that is, in the image forming mode for normal paper, the photoconductors 1Y, 1M, 1
C and 1K peripheral speeds and the moving speed of the intermediate transfer body 6 are made equal to the conveying speed of the recording material P in the fixing unit 24, and the image formation is performed in the second mode, ie, thick paper, glossy paper, OH
In forming an image on the P sheet, as described below, image formation is performed at a reduced conveying speed of the recording material P in the fixing unit 24.

In the image forming step of forming an image on thick paper, glossy paper, or OHP sheet, it is necessary to apply a larger amount of thermal energy to the toner than in the case of normal paper. The conveying speed of the heating roller 24A and the pressure roller 24B is set to a few
For example, the recording material P is conveyed at a rate of about 1/2 to 1/3 for fixing. By such control, sufficient fixation is performed even in the case of thick paper that absorbs a lot of heat, and an image having gloss matching glossy paper is obtained, and an image having sufficient transparency is carried. An OHP sheet is produced.

In the following, the single-color image forming unit 10
The peripheral speeds of the photoconductors 1Y, 1M, 1C, and 1K and the moving speed of the intermediate transfer member 6 when the image is formed by Y, 10M, 10C, and 10K are called image forming speeds. The transport speed is called a fixing speed.

In this embodiment, the following control is performed in response to the change in the fixing speed in the fixing unit 24 as described above. The conveyance of the recording material when the fixing speed is changed will be described with reference to FIG.

The image forming speed in the single-color image forming sections 10Y, 10M, 10C and 10K is always maintained at a constant value separately from the fixing speed in the fixing means 24. That is, in image formation on thick paper, glossy paper, and OHP sheets, the photoconductors 1Y, 1M, 1C, and 1K rotate in the direction of the arrow at the same constant peripheral speed as the image formation speed at the time of image formation on normal paper. Then, the intermediate transfer body 6 moves at the image forming speed H1 as shown by the arrow, and the formation of each monochromatic image and the formation of a multicolor image by the transfer of the monochromatic image (primary transfer) are performed.

Primary transfer of the last image, that is, photosensitive member 1K
After the transfer of the last part of the black image to the intermediate transfer member 6 from the point of time, the moving speed of the intermediate transfer member 6 is changed to the speed corresponding to the fixing speed H2 changed from the image forming speed H1. The intermediate transfer body 6 moves at the switched speed and transfers the multicolor image to the recording material P (secondary transfer).
Is performed.

In the second mode of the image forming apparatus according to the present embodiment in which the length L is shorter than the length of the recording material, the fixing speed H2 is set to a lower value than the image forming speed H1. Even when the next transfer and fixing are performed, as shown in FIG. 2, the intermediate transfer body 6 after the primary transfer is made to make one round so as to perform the transfer and fixing without any trouble. In order to shorten the image forming time, it is desirable that the above-described switching of the moving speed of the intermediate transfer body 6 be performed as much as possible, as shown in FIG.
The intermediate transfer body 6 is circulated at the image forming speed H1 until immediately before the intermediate transfer body 6 passes through the secondary transfer means 7A for the second time.
It is desirable to switch to a speed that matches the fixing speed H2 immediately before the next transfer unit 7A.

In the moving step S1 for forming an image on the intermediate transfer member 6, the intermediate transfer member 6 moves at the image forming speed H1, and then in the moving step S2, the intermediate transfer member 6 makes one round at the image forming speed H1. . After one round, in the moving step S3 in which the secondary transfer and fixing of the multicolor image on the intermediate transfer member 6 are performed, the intermediate transfer member 6 moves at a fixing speed H2 lower than the image forming speed H1, and the multicolor image is transferred. Transfer and fixing to the recording material P are performed.

By such control, it is possible to always perform image formation under constant conditions and to perform fixing at a desired fixing speed according to the type of the recording material P and the like. In addition, the distance between the secondary transfer unit 7A and the fixing unit 24 can be set short.

In the moving step S2 in which the intermediate transfer body 6 makes one round at the image forming speed H1, when the multicolor image on the intermediate transfer body 6 passes through the secondary transfer means 7A and the cleaning means 8A, Control is performed to make the secondary transfer unit 7A and the cleaning device 8A inactive. That is, control such as not applying the transfer voltage to the secondary transfer means 7A or separating the transfer roller of the secondary transfer means 7A from the intermediate transfer body 6 and cleaning the cleaning blade 81A with the intermediate transfer body 6
Is controlled. In the movement of the intermediate transfer body 6 after one round, the secondary transfer unit 7A and the cleaning unit 8
It goes without saying that A returns to the operating state.

Regarding the primary transfer means 7Y, 7M, 7C, 7K, in the moving step S2, for example, control such as separating the transfer roller from the intermediate transfer member may be performed.
Not required.

[0045]

According to the first, second, third, fourth, sixth, seventh or eighth aspect of the present invention, even when the fixing speed is changed, complicated image forming control switching accompanying the switching of the fixing speed is not performed. Thus, an image forming apparatus which is easy to control and operates stably is realized. In addition, a small-sized image forming apparatus is realized.

According to the fifth aspect of the present invention, thick paper, glossy paper, O
Good fixing is performed on a recording material that requires a fixing step different from that of ordinary paper such as an HP sheet, so that a versatile image forming apparatus is realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating control accompanying switching of a fixing speed.

[Explanation of symbols]

 1Y, 1M, 1C, 1K Photoconductor 2Y, 2M, 2C, 2K Charging means 3Y, 3M, 3C, 3K Exposure means 4Y, 4M, 4C, 4K Developing means 7A Secondary transfer means 7Y, 7M, 7C, 7K Primary Transfer unit 8A, 8Y, 8M, 8C, 8K Cleaning unit 24 Fixing unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/14 G03G 21/00 372 (72) Inventor Kazutoshi Kobayashi 2970 Ishikawacho, Hachioji City, Tokyo Konica shares In-house F-term (reference) 2H027 DA38 DC02 ED02 ED16 ED24 ED25 EE03 EE05 EE07 EF09 FA28 FA35 2H030 AB02 AD04 AD17 BB42 BB53 BB56 2H033 AA10 AA47 BA11 CA16 CA21 CA36 2H200 GA04 GA06 GA12 GA23 GA30 GB02 J25 GB03 JC12 JC19 LB02 LB13 LB39 PA10 PA11 PA12 PA23 PA26

Claims (8)

[Claims] 1. An image bearing member, an image forming member, an image forming means for forming a monochromatic image on the image forming member, and a primary transfer means for transferring a monochromatic image on the image forming member to the image bearing member A plurality of single-color image forming units, a secondary transfer unit that transfers a multicolor image formed by the single-color images transferred from the plurality of single-color image forming units to a recording material, and a multicolor image on the recording material. A first mode in which an image is formed by matching the fixing speed of the fixing unit with the image forming speed of the monochrome image forming unit; and the fixing speed is the image forming speed. And a second mode in which image formation is performed differently from the first mode. In the second mode, the image formation is performed until at least the transfer of the single-color image to the image carrier by the primary transfer unit is performed. Moves the image carrier at a speed Were, after completion of the transfer to the image bearing member of the single-color image, an image forming apparatus, characterized in that said image bearing member is moved by said fixing speed performing transfer by the secondary transfer unit. 2. The image forming apparatus according to claim 1, wherein the image forming in the plurality of single-color image forming units is performed at the image forming speed maintained invariably with the change in the fixing speed.
4. The image forming apparatus according to claim 1. 3. In the second mode, after the image carrier has moved a distance equal to or longer than the length of a recording material from the primary transfer means located most downstream in the moving direction thereof,
The image forming apparatus according to claim 1, wherein transfer is performed by a next transfer unit. 4. In the second mode, the multicolor image is transferred by the secondary transfer means after the image carrier makes one or more rounds from the last transfer of the single color image. Item 4. The image forming apparatus according to any one of Items 1 to 3. 5. The image forming apparatus according to claim 1, wherein in the second mode, the fixing speed is set to a value lower than the image forming speed. 6. A cleaning device for cleaning the image carrier after the transfer by the secondary transfer device, wherein the cleaning device is configured to clean at least when an image passes in a moving process in which the image carrier makes a round. The image forming apparatus according to claim 4, wherein the image forming apparatus is evacuated. 7. The image forming apparatus according to claim 4, wherein the secondary transfer unit is set to a non-operating state at least when an image passes in a moving step in which the image carrier makes one round. The image forming apparatus as described in the above. 8. The image forming apparatus according to claim 4, wherein the primary transfer unit is set to a non-operating state at least when an image passes in a moving step in which the image carrier makes one round. The image forming apparatus according to claim 7.