JPH08272224A - Multicolor image forming device and tension adjusting method for intermediate transfer body - Google Patents

Abstract

PURPOSE: To adjust tension in case of contacting/uncontacting to the same value with simple operation by using a stepping motor as a driving means for an eccentric cam. CONSTITUTION: When the eccentric cam 45 is rotated, a cam follower 42 integrated to a supporting member 41 and a cam follower 44 integrated to a supporting member 43 are brought into press-contact with the eccentric cam 45 by the tensile force of a belt, so that the supporting members 41 and 43 are rocked. The contact/uncontact operations of an intermediate transfer belt 19 with a photoreceptor 9 are carried out by the rocking. As the motor for driving the eccentric cam 45, the stepping motor is used. In other words, a shaft 45J is connected to the stepping motor and driven by it. When each rotation stopping position of the eccentric cam 45, in case of nontransferring and transferring, is inputted to a system control panel by a ten key, the stepping motor as a tensile force adjusting means is controlled to stop in a rotational position according to the instruction of the ten key, with a driving signal from the system control panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming apparatus and a tension adjusting method for an intermediate transfer member.

[0002]

2. Description of the Related Art Toner images of different colors formed on an image carrier are sequentially transferred onto a belt-shaped intermediate transfer member stretched between rollers, and the transferred toner images are collectively transferred onto a final transfer material. There is a multicolor image forming apparatus that obtains a full-color image by doing so.

In such a multicolor image forming apparatus, when the toner images of the respective color components formed on the image carrier are transferred onto a belt-shaped intermediate transfer member stretched between rollers, the intermediate transfer member is formed. In the apparatus that reciprocates the image and moves the intermediate transfer member toward and away from the image carrier in synchronism with this operation, the image is transferred in the sub-scanning direction (belt rotation direction) for the following reason. Image parallelism occurs.

Reason 1. The intermediate transfer body slips against the drive roller that supports the intermediate transfer body when the high-speed movement operation is stopped, especially in order to increase the copy speed during non-image formation and rotate it faster than the transfer speed. Resulting in.

Reason 2. When the intermediate transfer body is in contact with or separated from the image carrier, a difference in belt tension occurs due to variations in the size of the device, and especially in the case of an intermediate transfer body using a resin belt, there is a difference in the circumferential length of the belt. , That is,
The belt stretches. For this reason, the amount of expansion when the intermediate transfer member is rotated in the forward movement is different from the amount of expansion when it is rotated in the backward movement, and an image shift occurs.

Such image parallel deviation can be solved by equalizing the tensions applied to the belt at the time of transfer and at the time of non-transfer. As a means therefor, among a plurality of rollers supporting the intermediate transfer member, A technique is known in which one or a plurality of rollers are supported by a swingable support member and these support members are swung by an eccentric cam.

Here, the eccentric cam is driven by a motor via a half-rotation clutch. Due to the function of the half-rotation clutch, contact and separation are repeated every 180 ° rotation of the eccentric cam. It is supposed to be.

[0008]

In the prior art, the eccentric cam is driven by the motor via the half-rotation clutch, so that the tension at the time of contact and the tension at the time of separation are different from each other. However, in order to adjust these tensions, it is necessary to perform a troublesome work of shifting the position of the eccentric cam in the rotational direction with respect to the shaft.

The present invention provides a multicolor image forming apparatus and an intermediate transfer member tension adjusting method capable of adjusting the tension at the time of contact and the tension at the time of separation to the same value with a simple work content. With the goal.

[0010]

In order to achieve the above-mentioned object, the present invention provides: (1) Toner images of different colors formed on an image carrier are successively transferred onto a belt-shaped intermediate transfer member, A multicolor image forming apparatus that obtains a full-color image by batch-transferring a superimposed transfer toner image onto a final transfer material, wherein the intermediate transfer member is separated from the image carrier during the image registration during the superimposed transfer. Under the state (non-transfer), the intermediate transfer member is moved in the same direction as the image carrier in the forward direction or the reverse direction at a speed different from the state in which the intermediate transfer member is in contact with the image carrier (during transfer). Among the plurality of rollers that support the intermediate transfer member, one or more rollers are supported by a swingable support member, and
In the multi-color image forming apparatus in which the support member is swung by an eccentric cam, the tension applied to the intermediate transfer member during the transfer and the non-transfer can be adjusted to be equal to each other. Is a stepping motor (claim 1).

(2) Toner images of different colors formed on the image carrier are sequentially transferred onto a belt-shaped intermediate transfer member, and the transferred toner images are collectively transferred onto a final transfer material to form a full-color image. A multicolor image forming apparatus to obtain the image transfer, wherein the image transfer is performed on the intermediate transfer member in a state where the intermediate transfer member is separated from the image transfer member (when the transfer is not performed) during image registration during the superimposing transfer. It is carried out by moving in a forward direction which is the same direction as the image carrier or a reverse direction thereof at a speed different from the state in which it is in contact with the body (during transfer). home,
The one or more rollers are supported by a swingable support member, and this support member is swung by an eccentric cam so that the tension applied to the intermediate transfer body during transfer and during non-transfer is equal. In the adjustable multicolor image forming apparatus, an eccentric roller which is in contact with the intermediate transfer member and which can change the tension of the intermediate transfer member according to the amount of rotation thereof is provided (claim 2).

(3) In the multicolor image forming apparatus described in (1) or (2), the tension of the intermediate transfer member in a state where the intermediate transfer member is in contact with the image carrier (during transfer) is used as a reference. The tension of the intermediate transfer body is set when the intermediate transfer body is in contact with the image carrier (during transfer) (claim 3).

[0013]

The tension of the image-bearing intermediate transfer member during transfer and non-transfer can be individually adjusted by the stepping motor or the auxiliary tension adjusting means.

[0014]

【Example】

1. [Image Forming Apparatus Suitable for Implementing the Present Invention] As an example of an image forming apparatus suitable for implementing the present invention, an example of a color copying machine will be described with reference to FIGS.

A color image reading device (hereinafter referred to as a color scanner) 1 reads a color image,
The image of the original 3 is illuminated by the illumination lamp 4, and the reflected light is
An image is formed on the color sensor 7 through a mirror group such as mirrors 5-1, 5-2, and 5-3 and the lens 6.

The color image information of the original image formed on the color sensor 7 includes blue, green and red (hereinafter, B,
Abbreviated as G and R. ) Is read for each color separation light and converted into an electrical signal. In this example, the color sensor 7 is composed of B, G, and R color separation means and a photoelectric conversion element such as a CCD, and simultaneously reads three colors.

Based on the intensity levels of the B, G, and R color-separated image signals obtained by the color scanner 1 in this way, color conversion processing is performed by an image processing unit (not shown), and black (hereinafter Bk), cyan (hereinafter C), magenta (hereinafter M), yellow (hereinafter
(Denoted by Y) to obtain color image data.

These color image data are converted into a color image recording device (hereinafter referred to as a color printer) shown in FIG.
At, in Bk, C, M, Y color visualization,
Finally, a four-color full-color image is obtained by superimposing these visualized toner images.

That is, the operation method of the color scanner 1 for obtaining the image data of Bk, C, Y, and M is as follows: the illumination / mirror in FIG. 10 in response to the scanner start signal in timing with the operation of the color printer 2. The optical system scans the document in the direction of the left arrow to obtain image data of one color for each scan. By repeating this operation four times, four consecutive
Get color image data. Then, each time, the image is sequentially visualized by the color printer 2, and these are superposed to form a four-color full-color image.

Next, an outline of the color printer 2 will be described with reference to FIG. The writing optical unit 8 converts the color image data from the color scanner 1 into an optical signal and performs optical writing corresponding to the original image, and a photoconductor 9 as a drum-shaped image carrier as an image carrier. An electrostatic latent image is formed on.

The writing optical unit 8 includes a laser light source 8
-1, a light emission driving device (not shown), a polygon mirror 8-2, a rotation motor 8-3 for the polygon mirror 8-2, and an fθ lens 8
-4 and a reflection mirror 8-5.

The photoconductor 9 rotates counterclockwise as shown by the arrow, around which a photoconductor cleaning unit (including a pre-cleaning static eliminator) 10, a static elimination lamp 11, a charger 12, and a potential sensor. 13, a Bk developing device 14, a C developing device 15, an M developing device 16, a Y developing device 17, a development density pattern detector 18, an intermediate transfer belt 19 as an intermediate transfer member, and the like are arranged.

Each developing device rotates by bringing a brush of the developer into contact with the surface of the photoconductor 9 to develop the electrostatic latent image, and rotates the developing sleeves 14-1, 15-1, 16-1, 17-1. And a development paddle 1 that rotates to pump up and stir the developer
4-2, 15-2, 16-2, 17-2 and toner concentration detection sensors 14-3, 15-3, 16-3 for the developer.
17-3 and the like.

In the stand-by state, the developer on the developing sleeves is in the state of cutting off (development inoperative) state in all of the four developing devices, but the order of the developing operation (color image forming order) is Bk, An example of C, M and Y will be described below. However, the image forming order is not limited to this.

When the copy operation is started, the color scanner 1 starts reading the Bk image data at a predetermined timing. At the same time, the photoconductor 9 is driven to rotate counterclockwise by a photoconductor drive mechanism (not shown in FIG. 11), and the photoconductor 9 is uniformly charged by the charger 12.

On the basis of the Bk image data read by the color scanner, optical writing / latent image formation by laser light starts. Hereinafter, the electrostatic latent image based on the Bk image data is
k latent image. Each electrostatic latent image formed on the basis of each image data of C, M, and Y also conforms to this, and the C latent image, M latent image, Y
They will be referred to as latent images, respectively.

To enable development from the tip of the Bk latent image,
Before the latent image front end reaches the developing position of the Bk developing device 14, the developing sleeve 14-1 is started to rotate so that the developer spikes and the Bk latent image is developed with Bk toner. After that, the developing operation of the Bk latent image area is continued, but when the rear end of the Bk latent image passes the Bk developing position, the Bk developing sleeve 1 is quickly
The developer on the 4-1 is cut off to put it in a non-developing state. This is completed at least before the leading edge of the next C latent image arrives. In addition, the cutting sleeve is the developing sleeve 14-1.
The direction of rotation is switched to the direction opposite to that during the developing operation.

The Bk toner image formed on the photoconductor 9 is transferred to the surface of the intermediate transfer belt 19 which is driven at the same speed as the photoconductor (hereinafter, the transfer of the toner image from the photoconductor to the intermediate transfer belt is referred to as ""Primarytransfer"). The primary transfer is performed by applying a predetermined bias voltage to a transfer bias roller 20, which will be described later, while the photoconductor 9 and the intermediate transfer belt 19 are in contact with each other.

On the intermediate transfer belt 19, the Bk, C, M, and Y toner images sequentially formed on the photoconductor 9 are sequentially aligned on the same surface to form a belt transfer image of four-color superimposition. Performs batch transfer to transfer paper.

Toner images of Bk, C, M, and Y are sequentially formed on the photosensitive member 9, and the belt transfer images of four colors are formed by sequentially aligning the toner images on the same surface of the intermediate transfer belt in the order of formation. To be done. In this way, after the full-color toner image is formed, the full-color toner image is collectively transferred onto the transfer paper 24 as a transfer material. This transfer from the intermediate transfer belt 19 to the transfer paper 24 is called secondary transfer.

By the way, in the photoconductor 9, the process proceeds to the C process after the Bk process, but the C image data is read by the color scanner at a predetermined timing, and the C latent image is formed by writing the laser beam by the image data. .

The C developing device 15 is
After the trailing edge of the Bk image latent image has passed, and before the leading edge of the C latent image has reached, the developing sleeve 15-1 is started to rotate so that the developer is spiked and the C latent image is converted to C toner. To develop.

After that, the development of the C latent image area is continued, but when the trailing edge of the latent image passes, the developer on the C developing sleeve 15-1 is cut off in the same manner as in the case of the Bk developing device. . This is also completed before the leading edge of the next M latent image reaches. Regarding the steps M and Y, the respective operations of image data reading, latent image formation, and development are the same as those in B above.
Since it is the same as the steps k and C, the description thereof is omitted.

The intermediate transfer belt 19 is wound around a belt transfer bias roller 20, a driving roller 21 and a driven roller. A drive motor (not shown) is connected to the drive roller 21, and drive control is performed by this drive motor.

The belt cleaning unit 22 comprises a brush roller 22-1, a rubber blade 22-2, a belt contact / separation mechanism 22-3 and the like. After the Bk image of the first color is transferred onto the belt, while the second, third, and fourth colors are transferred on the belt, the contact / separation mechanism 22-3 separates the Bk image from the belt surface.

The paper transfer unit 23 is composed of a paper transfer bias roller 23-1, a roller cleaning blade 23-2 and a belt contact / separation mechanism 23-3. The paper transfer bias roller 23-1 is normally separated from the belt surface of the intermediate transfer belt 19, but the four-color superimposed images formed on the surface of the intermediate transfer belt 19 are collectively transferred onto the transfer paper 24. At this time, the contact / separation mechanism 23-3 presses the roller 23-1 at a timing, and a predetermined bias voltage is applied to the roller 23-1 to transfer to the transfer sheet.

As shown in FIG. 2, the transfer paper 24 is driven by the feed roller 25 and the registration roller 26 in accordance with the timing when the leading end of the four-color superposed image on the surface of the intermediate transfer belt 19 reaches the paper transfer position. The sheet is fed between the sheet 21 and the sheet transfer bias roller 23-1, and is secondarily transferred. The transfer paper 24 after transfer is conveyed by the conveyor belt 27 and sent to the fixing device to fix the image, and then discharged to the tray.

As a moving method of the intermediate transfer belt 19, a reciprocating (quick return) method described below can be considered as an operation method after the belt transfer of the Bk toner image of the first color is completed up to the rear end portion.

Reciprocating (quick return) system When the belt transfer of the Bk image is completed, the intermediate transfer belt 19 is separated from the surface of the photosensitive member 9 to stop the forward movement, and at the same time, to return in the reverse direction at a high speed. By this return operation, the front end position of the Bk image on the surface of the intermediate transfer belt 19 passes through the belt transfer equivalent position in the opposite direction, and after moving for a preset distance, it is stopped and brought into a standby state.

Next, when the front end of the C toner image on the photoconductor 9 side reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 is restarted in the forward direction. Further, the intermediate transfer belt 19 is brought into contact with the surface of the photoconductor 9 again. Also in this case, the C image is transferred under the condition that it is accurately overlapped with the Bk image on the surface of the intermediate transfer belt 19.

After that, by the same operation, M,
Proceed to the Y image step to obtain a belt transfer image of four colors.

Subsequent to the belt transfer process of the Y toner image of the fourth color, the toner image does not return but moves forward at the same speed to collectively transfer the four-color superimposed toner image on the surface of the intermediate transfer belt 19 onto the transfer paper 24.

With this method, the transfer paper 24 to which the four-color superposed toner images are collectively transferred from the surface of the intermediate transfer belt 19 is conveyed to the fixing device 28 by the conveying belt 27, and the fixing roller 28-controlled to a predetermined temperature. The toner image is fused and fixed by 1 and the pressure roller 28-2 and is carried out to the copy tray 29 to obtain a full-color copy.

On the other hand, the surface of the photosensitive member 9 after the belt transfer is cleaned by the photosensitive member cleaning unit 10 including the pre-cleaning static eliminator 10-1, brush roller 10-2, rubber blade 10-3, etc. To eliminate static electricity evenly.

The surface of the intermediate transfer belt 19 after the toner image is transferred onto the transfer paper 24 is cleaned. This cleaning is performed by pressing the belt cleaning unit 22 again with the contact / separation mechanism 22-3.
In the case of repeat copy, the operation of the color scanner 1 and the image formation on the photoconductor 9 are performed at a predetermined timing after the second Bk (1
Go to the image process.

Further, in the case of the intermediate transfer belt 19, following the batch transfer process of the first four-color superimposed image onto the transfer paper,
The second Bk toner image is transferred to the belt by the belt cleaning unit 22 on the surface thereof. After that, the same operation as the first sheet is performed.

The transfer paper cassettes 30, 31, 32,
Reference numeral 33 stores transfer paper of various sizes, and paper of a size designated by an operation panel (not shown) is fed and conveyed from the storage cassette to the registration roller 26 at a timing. Reference numeral 34 indicates a sheet for an overhead projector or a sheet feed tray for manually inserting a transfer sheet of thick paper.

Up to this point, the description has been given of the copy mode for obtaining four full colors, but in the case of the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated number of colors and the number of times. Will be done.

In the case of the single color copy mode, until the predetermined number of sheets are finished, only the developing device of that color is in a developing operation (agent standing) state, and the intermediate transfer belt 19 is placed on the photoreceptor 9 surface. It is driven in the forward direction at a constant speed while being in contact with the belt, and the belt cleaning unit 22 also performs the copying operation while being in contact with the intermediate transfer belt 19.

2. Embodiment of the Invention of Claim 1 [Embodiment 1] Embodiments of means for changing the belt tension when the intermediate transfer belt 19 is in contact with and separated from the photoconductor 9 are shown in FIGS. 1, 2, 3 and 4. It will be described based on. As described with reference to FIG. 11, the intermediate transfer belt 19 is supported by a plurality of rollers with a part thereof facing the photoconductor 9.

The intermediate transfer belt 19 includes a bias roller 20 to which a bias voltage is applied to transfer the toner image on the photosensitive member to the belt, and a roller 54 for forming a nip at the belt transfer portion together with the bias roller 20. In order to face the photoconductor 9 so as to be able to come into contact with and separate from the photoconductor 9, the support member 41 for supporting these rollers is pivotally supported, and this support member is supported so as to be swingable about a fulcrum 47. There is.

The tension roller 53 for supporting the intermediate transfer belt 19 in order to apply the required belt tension to the intermediate transfer belt 19 is also the tension roller 5
3 is pivotally supported on the support member 43, and the support member 43 is swingable about a fulcrum 48. Here, the tension roller 53 is slidably supported on the bearing member 53a by the support member 43. The bearing portion 53a is capable of reciprocating in a groove formed in the support member 43, and is pressed against the intermediate transfer belt by an urging member 46 formed of a stretchable spring interposed in the groove.

The support members 41 and 43 are provided with cam followers 42 and 44, respectively, and an eccentric cam 45 that rotates together with a shaft 45J provided in an eccentric position so as to be in common contact with these cam followers 42 and 44.
Is provided.

When the eccentric cam 45 is rotated, the belt tension causes the cam follower 42 integral with the support member 41 and the cam follower 44 integral with the support member 43 to come into pressure contact with the eccentric cam 45, whereby the support members 41, 43 swing. Move.
By this swing, the contact / separation operation of the intermediate transfer belt 19 with respect to the photoconductor is performed.

FIGS. 1, 2 and 3 show how the swinging amounts of the supporting members 41 and 43 are different and the belt tension is different by changing the rotational angle position of the eccentric cam 45 when the belts are separated. FIG. 4 shows how the belt contacts.

The belt tension changes according to the length of the biasing member 46. Now, the length of the urging member 46 according to the rotational angle position of each eccentric cam 45 shown in FIGS. 1, 2, 3, and 4 is L
If T1, LT2, LT3 and LT4 are set, the relative positions of the respective members can be set so that LT1 <LT2 <LT3 and LT2 = LT4. At this time, the belt tension corresponding to each is set to T1 when the length of the biasing member 46 is LT1, and L
When T2 is T2 and LT3 is T3, the following relationship is established: T3 <T2 <T1, T2 = T4. Therefore, by changing the rotation stop position (rotation angle) of the eccentric cam 45, the intermediate transfer belt 1
FIG. 2 corresponds to a non-transfer state in which 9 is separated from the photoconductor 9.
4 and the state shown in FIG. 4 corresponding to the transfer when the intermediate transfer belt 19 is in contact with the photoconductor 9, it is possible to adjust the belt tension during non-transfer and during transfer to be equal. Is.

Further, by adjusting the length of the biasing member 46, it is possible to adjust the magnitude of the belt tension while satisfying T2 = T4.

The optimum rotation stop position of the eccentric cam 45 differs depending on the manufacturing error range for each multicolor image forming apparatus. Therefore, the optimum cam stop position is input by a numeric keypad provided on the operation panel of the multicolor image forming apparatus. Can be set by.

In this example, a stepping motor is used as a motor for driving the eccentric cam 45. That is, FIG.
The shaft 45J shown in FIG. 4 is connected to and driven by the stepping motor. When the rotation stop positions of the eccentric cams 45 at the time of non-transfer and transfer are input to the system control plate by the ten-key shown in FIG. 9, a drive signal from the system control plate 60 causes a stepping motor as tension adjusting means. However, it is controlled to stop at the rotational position in accordance with the instruction of the ten-key pad.

Since the stepping motor can control the stop of the rotational position at an arbitrary minute angle, the rotational position of the eccentric cam 45 where the tension is equal when the intermediate transfer belt is in contact with and separated from the photoconductor. Can be easily set by operating the ten-key pad, and the adjustment work can be performed very easily as compared with the prior art.

Example 2 In the above example, the support member 41
The cam followers 42 and 44 of the support member 43 and the support member 43 are commonly driven by the eccentric cam 45.
As shown in (a), the support member 41 and the support member 43 are provided with dedicated eccentric cams. That is, as shown in FIGS. 7 and 8, the shafts 45A provided at the eccentric positions of the eccentric cam 45A, which is the positioning means of the support member 41, and the eccentric cam 45B, which is the positioning member of the support member 43, respectively.
J and 45BJ respectively. These eccentric cams 4
5A and 45B are driven by the shafts 45AJ and 4 of these cams.
The stepping motor is provided every 5 BJ.

In this example, as shown in FIGS. 7 and 8A, the belt tension when the intermediate transfer belt 19 is separated from the photosensitive member 9 (when the transfer is not performed) and when the intermediate transfer belt 19 is in contact with the photosensitive member 9 as shown in FIG. The belt tension during transfer) can be changed independently.

At this time, the cam positions of the eccentric cams 45A and 45B in the contact state (the state shown in FIG. 7) are always constant, and the eccentric cam 4 in the separated state (the state shown in FIG. 8A).
By adjusting one or both of the cam positions of 5A and 45, that is, by adjusting the tension at the time of separation, while satisfying T2 = T4, the magnitude of the tension is adjusted. You can also

In FIGS. 8B and 8C, the eccentric cam 45A is used.
As for the above, it is shown that by driving the stepping motor with respect to the distance x at a certain rotation stop position, it is possible to change only the minute movement amount Δx. As a means for designating the rotational position of each of these eccentric cams, the numeric keypad shown in FIG. 9 can be used.

The same control can be performed by mounting two kinds of cams on one cam shaft so that the rotational positions can be adjusted and driving them by a stepping motor.

3. Invention Corresponding to Claim 2 In FIGS. 5 and 6, an eccentric roller 49 is provided which is rotatable in contact with the intermediate transfer member to change the belt tension according to the rotational position. The eccentric roller 49 is a kind of cam whose rotary shaft 49J is displaced to the eccentric position. In this device, according to the configuration shown in FIG. 1 to FIG.
Although it has 1, 43, an eccentric cam 45, etc., the rotation of the eccentric cam does not need to be performed by a step motor, and as in the prior art, it is rotated by a half-rotation clutch via a normal motor. Such a configuration is sufficient. This eccentric cam 4
5 does not have the function of setting the belt tension, but has only the function of bringing the intermediate transfer belt 19 into contact with and away from the photoconductor 9.

It is the eccentric roller 49 that determines the belt tension during contact and separation. The eccentric roller 49 is rotatable, and a braking means for fixing the position at an arbitrary rotating position is attached. The turning position of the eccentric roller 49 may be manually adjusted, or a stepping motor capable of finely controlling the turning angle may be used. When this stepping motor is used, the ten-key input shown in FIG. 9 may be used.

In FIGS. 5 and 6, the bite amount of the eccentric roller 49 with respect to the intermediate transfer belt 19 at the time of separation is d.
B, the bite amount at the time of contact is dA, and the belt tension with respect to the bite amount dB is TB, the bite amount d
When the belt tension with respect to A is TA and dB <dA, the belt tension is TB <TA. Therefore, the tension of the intermediate transfer belt 19 can be adjusted by setting the rotation position of the eccentric roller 49.

For example, the belt tension when the intermediate transfer belt 19 contacts the photosensitive member 9 is set by adjusting the length of the urging member 46 so as to have a value suitable for transfer.
At that time, if the eccentric roller 49 is set so that the eccentric roller 49 is separated from the intermediate transfer belt 19, the belt tension when the intermediate transfer belt 19 is separated from the photoconductor 9 causes the eccentric roller 49 to move to the intermediate position. The transfer belt 19 is pressed, and the degree of this pressing is obtained by adjusting the rotational position of the eccentric roller 49.

Thus, in this example, the eccentric cam 45 is
It is sufficient to have only the function of determining the positions of the supporting members 41 and 43 at the time of contact and separation, and the function is separated from the eccentric roller 49 provided as a means for giving the belt tension, so that the belt tension can be adjusted stably. You can

4. Description Corresponding to Claim 3 In the configuration of the first embodiment shown in FIGS. 1 to 4, the eccentric cam 45 is used.
Drive the support members 41 and 43 in common, the rotation of the eccentric cam 45 changes not only the support member 43 but also the position of the support member 41. Therefore, the support member 41 when the intermediate transfer belt 19 contacts the photoconductor 9
The swing position of is adjusted at the time of manufacturing so that a proper nip is formed. Then, when the belt tension is adjusted, the swing position of the support member 41 at the time of contact is changed. It is not preferable to make adjustments.

When the swing range of the support member is changed when the intermediate transfer belt 19 contacts the photoconductor 9, the nip of the transfer section also changes, and the electric field of the transfer section also varies in voltage (current) and nip width. Because it depends. If the margin of this electric field is sufficient, there is not much effect, but if the margin is small, problems such as excessive transfer and insufficient transfer will occur.

Therefore, in each of the examples described in [Example 1], [Example 2], and the description corresponding to claim 2, the intermediate transfer belt 19 was first brought into contact with the photosensitive member 9. Based on the belt tension of the intermediate transfer belt 19 at the time of transfer, which is a state (this state is usually set as a value for obtaining an appropriate nip at the time of manufacturing the apparatus), the belt tension becomes equal to this belt tension. In addition, the belt tension is set when the intermediate transfer belt 19 is separated from the photoconductor 9 and is not transferred.

At the time of this adjustment, in the case of the example shown in FIGS. 1 to 4 related to the description of the above-mentioned [Embodiment 1], the eccentric cam 5 is used.
Drive the support members 41 and 43 in common, the rotation of the eccentric cam 45 changes not only the support member 43 but also the position of the support member 41. Therefore, in order to adjust the belt tension during non-transfer without changing the position of the supporting member during transfer, the rotational position of the eccentric cam 45 is adjusted, and when there is no adjustment margin, the biasing member 46 is used. The length of itself may be adjusted together.

In this respect, in the case of the example shown in FIGS. 7 and 8 according to the description of the [Second Embodiment], the eccentric cam 45A drives the support member 41, and the eccentric cam 45B drives the support member 43. So that they are driven independently,
The belt tension during non-transfer can be easily adjusted.

Similarly, in the case of the example described with reference to FIGS. 5 and 6 according to the description of claim 2,
Since the belt tension during non-transfer can be adjusted individually without changing the oscillation position of the support member 41 during transfer, the belt tension can be adjusted without changing the proper nip.

Incidentally, in the case of the example shown in FIGS. 7 and 8 according to the description of [Second Embodiment] and in the example described in FIGS. 5 and 6 according to the description of claim 2. In comparison with the former technique, the number of supporting rollers of the intermediate transfer belt is smaller than that of the latter technique, so that the rotation torque of the belt drive roller 21 is small and the power consumption of the drive motor is also small. There are advantages.

5. Advantages of Embodiments In the embodiment described in [Embodiment 1], an eccentric cam and a stepping means are used as tension adjusting means capable of adjusting the belt tension so that the tensions applied to the belt during transfer and non-transfer are equal. Since it has a motor, there is no difference in the circumferential length of the belt during transfer and during transfer, color misregistration can be prevented, and good images can be obtained.

The second embodiment has eccentric cams 45A and 45B, and these eccentric cams are independently driven by a stepping motor, so that the stop position can be freely set. Adjustment can be performed, a difference does not occur in the peripheral length of the belt at the time of transfer and non-transfer, color misregistration can be prevented, and a good image can be obtained.

In the example described in the description corresponding to claim 2, as shown in FIGS. 5 and 6, only when contacting or separating, contacting the intermediate transfer belt 19 or contacting and separating. Eccentric roller 4 as a member having different contact pressures
9 and the contact pressure or the difference between the contact pressures can be adjusted, there is no difference in the belt circumferential length at the time of transfer and at the time of non-transfer, color shift is prevented, and a good image is obtained. Can be obtained.

In the apparatus according to the third aspect, since the adjustment method does not change the nip between the photosensitive member and the intermediate transfer belt, the optimum transfer bias does not shift from machine to machine, and color shift is prevented. A good image can be obtained.

[0082]

According to the present invention, the tension at the time of contact and the tension at the time of separation can be adjusted to the same value with a simple work content.

[Brief description of drawings]

FIG. 1 is a configuration diagram of main parts for explaining a non-transfer state of a multicolor image forming apparatus as an embodiment according to claim 1 of the present invention.

FIG. 2 is a configuration diagram of a main part for explaining a non-transfer state of the multicolor image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a main part configuration diagram illustrating a non-transfer state of the multicolor image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of main parts for explaining a transfer state of the multicolor image forming apparatus according to the first embodiment of the present invention.

FIG. 5 is a main part configuration diagram for explaining the state of the eccentric roller in the non-transferring state of the multicolor image forming apparatus according to another embodiment of the first aspect of the present invention.

FIG. 6 is a main part configuration diagram for explaining the state of the eccentric roller in the non-transferring state of the multicolor image forming apparatus according to another embodiment of the first aspect of the present invention.

FIG. 7 is a configuration diagram of a main part for explaining a transfer state of the multicolor image forming apparatus according to the second embodiment of the present invention.

FIG. 8 is a configuration diagram of a main part for explaining a non-transfer state of the multicolor image forming apparatus according to the second embodiment of the present invention;
FIG. 6 is a diagram illustrating a contact state of the eccentric cam with a cam follower.

FIG. 9 is a block diagram of a control system suitable for implementing the present invention.

FIG. 10 is a diagram illustrating an overall configuration of a multicolor image forming apparatus suitable for implementing the present invention.

FIG. 11 is a diagram illustrating a configuration around a photoconductor and an intermediate transfer belt suitable for implementing the present invention.

[Explanation of symbols]

 41 support member 43 support member 45 eccentric cam 45A eccentric cam 45B eccentric cam 46 biasing member 49 eccentric roller

Front Page Continuation (72) Inventor Hideya Furuta 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd.

Claims (3)

[Claims] 1. A full-color image is obtained by successively superposing and transferring toner images of different colors formed on an image carrier onto a belt-shaped intermediate transfer member, and transferring the superposed transfer toner images to a final transfer material at once. In a multicolor image forming apparatus, the image alignment at the time of the superposed transfer is performed under a state (when the transfer is not performed) in which the intermediate transfer body is separated from the image carrier.
The intermediate transfer member is moved in a forward direction which is the same direction as the image carrier or a reverse direction thereof at a speed different from the state in which the intermediate transfer member is in contact with the image carrier (during transfer).
Of the plurality of rollers that support the intermediate transfer member, one or a plurality of rollers is supported by a swingable support member, and the support member is swung by an eccentric cam to perform the transfer and the non-transfer. In the multicolor image forming apparatus, in which the tension applied to the intermediate transfer member can be adjusted to be the same, the driving means for the eccentric cam is a stepping motor. 2. A full-color image is obtained by sequentially superposing and transferring toner images of different colors formed on an image carrier onto a belt-shaped intermediate transfer member, and transferring the superposed transfer toner images to a final transfer material at once. In a multicolor image forming apparatus, the image alignment at the time of the superposed transfer is performed under a state (when the transfer is not performed) in which the intermediate transfer body is separated from the image carrier.
The intermediate transfer member is moved in a forward direction which is the same direction as the image carrier or a reverse direction thereof at a speed different from the state in which the intermediate transfer member is in contact with the image carrier (during transfer).
Of the plurality of rollers that support the intermediate transfer member, one or a plurality of rollers is supported by a swingable support member, and the support member is swung by an eccentric cam to perform the transfer and the non-transfer. In the multicolor image forming apparatus in which the tension applied to the intermediate transfer body can be adjusted to be the same, the eccentricity that is in contact with the intermediate transfer body and can change the tension of the intermediate transfer body according to the rotation amount thereof. A multicolor image forming apparatus having a roller. 3. The multicolor image forming apparatus according to claim 1, wherein the tension of the intermediate transfer body in a state where the intermediate transfer body is in contact with the image carrier (during transfer) is used as a reference.
A tension adjusting method for an intermediate transfer member, comprising setting a tension of the intermediate transfer member in a state where the intermediate transfer member is in contact with the image carrier (during transfer).