JP3113730B2 - Recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus using a belt. 2. Description of the Related Art Some electrophotographic recording apparatuses using a belt use an intermediate transfer belt or a photosensitive belt as a belt. The belt is tensioned and supported by the roller, but if the roller is eccentric, a belt feeding error occurs, causing a color misalignment. In order to prevent the image quality from deteriorating, it is necessary to prevent such a shift in the overlapping position of the colors.

[0002]

2. Description of the Related Art A conventional electrophotographic recording apparatus using a belt is, for example, as shown in FIG.
In FIG. 8, when a recording command is issued from a control unit (not shown), the feeding operation of the recording paper 1 is started. The recording paper 1 taken out of the paper cassette 2 is temporarily stopped at the nip portion of the registration roller 4 stopped via the roller 3, and the timing with the recording process is taken. After this,
The recording paper 1 is sent to the transfer roller 5 by the registration roller 4 whose rotation has resumed, and the color toner image superimposed on the intermediate transfer belt 6 is transferred onto the recording paper 1. The recording paper 1 is further sent to a fixing device 7, and a fixing roller 8,
The toner image is fixed on the recording paper 1 by the heat and pressure given by the pressure roller 9. The photosensitive drum 11 is cleaned by the cleaner blade 10.

[0003] The toner image is formed on the photosensitive drum 11 by a charger 12, an exposure system 13, and developing units 14 to 17 around the photosensitive drum 11 in the order of YMCK for each rotation of the drum by a known electrophotographic process. Is formed. The formed toner images are sequentially transferred onto the intermediate transfer belt 6 conveyed while being in contact with the photosensitive drum 11 by the discharge of the transfer corotron 13 (primary transfer).

During the superposition of four colors, the cleaner blade 19 and the transfer roller 5 are separated from the intermediate transfer belt 6. When the transfer of the four colors of YMCK is completed, the transfer roller 5
Is pressed against the backup roller 20, and the color toner image is collectively transferred to the recording paper 1 (secondary transfer). When the transfer to the recording paper 1 is completed, the transfer roller 5 is separated from the backup roller 20. Further, the cleaner blade 19 is pressed against the drive roller 21 to clean the intermediate transfer belt 6 after the transfer, and is separated from the drive roller 21 after the cleaning is completed. Note that 22,
23 is a support roller.

[0005] By repeating such operations, color printing is performed one after another.

[0006]

However, in such a conventional recording apparatus, if the drive roller 4 of the intermediate transfer belt 6 is eccentric, a belt feeding error occurs,
This was the cause of misregistration of the colors. As a countermeasure, by utilizing the fact that a belt feed error due to roller eccentricity occurs in one rotation period of the drive roller, the circumference of the drive roller 21 is reduced to an integral fraction of the circumference of the intermediate transfer belt 6 to reduce the intermediate length. There has been a method of adjusting the misregistration phase of each color on the transfer belt 6 to reduce the misregistration (see, for example, JP-A-59-182139).

However, the rollers 20 other than the driving roller 21
It has been found that even when there is an eccentricity, a positional deviation having a cycle of the circumference of the roller 20 occurs. When all the rollers have the same diameter, the peripheral length of the driving roller 21 is set to be substantially an integral multiple of the peripheral length of the intermediate transfer belt 6, so that the period of the roller feeding error is automatically aligned. There was no problem of displacement. However, when rollers having different diameters are used, the overlapping positions of the colors are shifted for the above-mentioned reason, and the image quality is reduced.

A similar problem occurs when not only the intermediate transfer belt but also a photoreceptor belt is used. That is, in the case of the drive roller 21, the surface is made of a material having high friction such as rubber so that the friction coefficient with the intermediate transfer belt 6 is increased in order to drive the intermediate transfer belt 6 without slipping. On the other hand, in the case of other rollers, this is not particularly necessary, and a metal such as plastic or SUS is used as it is without performing rubber lining or the like which increases the cost.

In the case of plastic or metal, since the coefficient of friction with the intermediate transfer belt 6 is as low as 0.1 to 0.2, slippage occurs between belts, and the belt feeding speed is hardly affected by the roller eccentricity. For this reason, roller eccentricity other than the drive roller has not conventionally been a problem. However, in the case of a color printer, metal is used for the rollers 22 and 23, while the roller 20 is a roller whose surface is lined with rubber, and has a friction coefficient of 0.8 or more with the intermediate transfer belt 6 and the driving roller. It is as high as 21. If the coefficient of friction of the roller 20 is high, slippage does not easily occur, and the roller 20 is affected by eccentricity of the roller.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a recording apparatus capable of preventing the occurrence of color misregistration and improving image quality. And

[0011]

In order to achieve the above-mentioned object, the present invention provides an image transfer method for transferring an image formed on a photoreceptor to an intermediate transfer member.
A recording apparatus for recording on a recording sheet after the transfer, the
No timing marker and identification marker on the intermediate transfer member
In addition to providing a plurality of
Each of these timing markers and identification markers is detected.
Detecting means for outputting, one output of the detecting means to the other
By counting the time until output, the timing marker
Marker identification means for identifying the
Delay means to make the delay time until
Things.

[0012]

According to the present invention, belts usages becomes uniform, it is possible to extend the life of the intermediate transfer belt 61 is reduced. In addition, since the circumference of the intermediate transfer belt 61 and the circumference of the photosensitive drum are set to be the same, not only the intermediate transfer belt 61 but also the location where the photosensitive drum is used changes in conjunction therewith. The service life can be extended.

[0013]

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 31 denotes a photosensitive drum. Around the photosensitive drum 31, a charger 32, an exposure system 33, and developing units 34 to 3 for developing a YMCK color toner image on the photosensitive drum 31.
7. A cleaner blade 38 is provided.

Reference numeral 39 denotes an intermediate transfer belt (belt).
On the intermediate transfer belt 39, the toner images on the photosensitive drums 31 are sequentially transferred by being superposed by the discharge of the transfer corotron 40. Reference numeral 41 denotes a cleaner blade. The cleaner blade 41 comes into pressure contact with the driving roller 42, and the intermediate transfer belt 3
9 is cleaned.

Reference numeral 43 denotes a transfer roller.
Presses against the backup roller 44 to transfer the toner image onto the recording paper 45. The recording paper 45 is taken out of the paper cassette 46, and is conveyed at predetermined timing by a registration roller 48 via a roller 47. Reference numeral 49 denotes a fixing device. The fixing device 49 includes a fixing roller 50 and a pressure roller 51, and fixes a toner image on the recording paper 45.

Here, the intermediate transfer belt 39 is composed of a driving roller 42, a backup roller 44 and a support roller 5.
It is supported and tensioned by 2,53. The drive roller 42 drives the intermediate transfer belt 39 without slipping.
It is made of a rubber material such as urethane rubber so that the coefficient of friction with the intermediate transfer belt 39 is increased. Similarly, the backup roller 44 has a surface lining with rubber or the like. This is to uniformly press the recording paper 45 against the recording paper 45 and to increase the transfer time in the nip portion.

Therefore, at least the peripheral lengths of the driving roller 42 and the backup roller 44 are set to an integral fraction of the peripheral length of the intermediate transfer belt 39. Support roller 52,
53 is made of metal such as stainless steel and has a low friction coefficient. For this reason, slippage occurs between the belts, and the feed speed of the intermediate transfer belt 39 is less likely to be affected by the roller eccentricity. Is desirably set so as not to be affected by roller eccentricity.

As a result, as shown in FIG.
With respect to the feed error generated by 2, 44, 52, and 53, the phase of the position shift was reproduced for each rotation of the belt, and the color shift due to roller eccentricity was almost eliminated. In FIG.
The phases of the first color of Y (yellow) and the second color of M (magenta) are almost the same, and there is almost no displacement of the color superposition position.

Although the present embodiment has been described using an example in which a belt-shaped intermediate transfer member is used, it is needless to say that the present invention can be applied to a photosensitive belt. 3 to 7 show another embodiment of the present invention. In FIG. 3, reference numeral 61 denotes an intermediate transfer belt (intermediate transfer body) whose peripheral length is set to be equal to the peripheral length of the photosensitive drum. The intermediate transfer belt 61 includes a driving roller 62, a backup roller 63, a tension roller 64, and a support roller. It is supported by 65 and 66 and is tensioned.

On the intermediate transfer belt 61, for example, the timing markers 67a to 67d for determining the printing timing and the identification markers 68a to 68d for identifying the timing markers 67a to 67d so as to divide the belt circumference into four parts.
68d are provided. In addition, the timing marker 6
Optical sensor (detection means) 6 for detecting 7a to 67d
9 and optical sensors 70 for detecting the identification markers 68a to 68d, respectively.

The timing markers 67a to 67d and the identification markers 68a to 68d have a predetermined positional relationship as shown in FIG. That is, the identification marker 67
a, the deviation between the timing marker 68a and the identification marker 67b is Lb,
The difference between the identification marker 67c and the timing marker 68c is Lc, and the identification marker 67d and the timing marker 68c.
Assuming that the deviation of d is Ld, it is set so that La <Lb <Lc <Ld.

Therefore, the marker identifying circuit (marker identifying means) 72 in the control section 71 is provided with the identifying markers 68a to 68a-6.
After detecting 8d, timing markers 67a to 67d
By counting the time until the detection of
a, Lb, Lc, Ld can be identified, whereby the timing markers 67a to 67d can be identified.

FIG. 5 is a block diagram of the mark identification circuit 72. In FIG. 5, the counter 72A starts the clock counting operation when the optical sensor 70 detects the identification markers 68a to 68d, and ends the counting when the optical sensor 69 detects the timing markers 67a to 67d, The count value is output to the comparison circuit 72B.

The comparison circuit 72B stores the count value and the memory 7
By comparing the number of clocks corresponding to the shifts La to Ld stored in the 2C, if they match, the timing markers 67a to 67d are identified, and the counter operation is reset. The control unit 71 has a delay circuit (delay means) 73 for varying a delay time from when the timing markers 67a to 67d are detected until a print command is issued, and sets the delay time to, for example, five ways. I can do it.

FIG. 6 is a block diagram of the delay circuit 72.
After the optical sensor 69 detects the timing markers 67a to 67d, the delay time T until the exposure start signal is output is adjusted (see FIG. 7). As the delay time T, for example, five patterns are prepared, and the number of clocks corresponding to the delay time T is stored in the memory 72C in advance.

The counter 72A starts the clock counting operation after the output of the optical sensor 69, and outputs the counted number to the comparison circuit 72B. The comparison circuit 72C compares the count value with the number of clocks corresponding to each delay time T in the memory 72C, and when they match, outputs an exposure start signal and resets the counting operation.

As described above, the print start position is set at 20 positions on the belt circumference by a combination of the selection of the timing markers 67a to 67d for setting the print start timing and the selection of the delay time from the detection of the marker to the start of printing. Can be. In this way, the setting of the print head position can be switched every fixed number of sheets, for example, every 50 printed sheets.

As a result, the places where the belt is used become uniform,
The service life of the intermediate transfer belt 61 can be extended. Further, since the circumference of the intermediate transfer belt 61 and the circumference of the photosensitive drum are set to be the same, not only the intermediate transfer belt 61 but also
Since the use location of the photoconductor drum changes in conjunction with it,
The life of the photosensitive drum can be extended.

In this embodiment, the intermediate transfer belt 61 is used.
However, it is needless to say that the present invention can also be applied to a drum-shaped intermediate transfer member.

[0031]

As described above, according to the present invention, the life of the intermediate transfer member and the photosensitive member can be extended.
You.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a displacement of an overlapping position.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between an identification marker and a timing marker;

FIG. 5 is a block diagram of an identification circuit.

FIG. 6 is a block diagram of a delay circuit;

FIG. 7 is a diagram showing the timing of an exposure start signal.

FIG. 8 shows a conventional example.

[Explanation of symbols]

 31: photosensitive drum 32: charging device 33: exposure system 34-37: developing device 38: cleaner blade 39: intermediate transfer belt (belt) 40: transfer corotron 41: cleaner blade 42: drive roller (roller) 43: transfer roller 44 : Backup roller (roller) 45: recording paper 46: paper cassette 47: feed roller 48: registration roller 49: fixing device 50: fixing roller 51: pressure roller 52, 53: support roller (roller) 61: intermediate transfer belt ( (Intermediate transfer member) 62: drive roller 63: backup roller 64: tension roller 65, 66: support roller 67a to 67d: timing marker 68a to 68d: identification marker 69, 70: optical sensor (detection means) 71: control unit 72: marker identification circuit (marker identification means) 72A: counter 72B: Comparison circuit 72C: Memory 73: delay circuit (delay means) 73A: counter 73B: Comparison circuit 73C: Memory

Continuation of the front page (72) Inventor Hideo Kato 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-2-12271 (JP, A) JP-A-4-276774 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 15/01 114 G03G 21/14

Claims (1)

(57) [Claims] An image formed on a photosensitive member is transferred to an intermediate transfer member.
In a recording apparatus for recording on recording paper after copying, a timing marker and an identification marker are provided on the intermediate transfer body.
With a plurality of
In addition, these timing markers and identification markers are
Detection means for detecting each of them, and one output of the detection means
By counting the time to the other output,
Marker identification means for identifying a marker for printing, and a printing finger after identification.
Delay means to make the delay time before issuing a command variable
A recording device, comprising: