JP3484910B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrophotography.
Printers, facsimile machines, and copiers
Etc.Image forming deviceIt is about. [0002] 2. Description of the Related Art Generally, image formation using electrophotographic technology
The apparatus includes a photosensitive member having a photosensitive layer on an outer peripheral surface, and the photosensitive member.
Charging means for uniformly charging the outer peripheral surface of the device, and the charging means
By selectively exposing the outer peripheral surface uniformly charged by
Exposure means for forming an electrostatic latent image, and
Visible by applying toner as a developer to the formed electrostatic latent image
Developing means for forming an image (toner image) and the developing means
A transfer for transferring the developed toner image to a transfer medium such as paper.
Shooting means. Then, the toner image developed on the photoreceptor is
As a transfer means for transferring to a transfer medium such as paper, photosensitive
Transfer color toner images formed on the body sequentially (primary transfer
The toner image is recorded on the intermediate transfer belt.
Intermediate transfer method for batch transfer (secondary transfer) to recording media is known
Have been. [0004] In addition, Japanese Patent Application No. 7-322667 discloses
The intermediate transfer belt has a conductive layer so that the primary transfer belt
The resistance RT from the power supply to the conductive layer to the conductive layer
The primary resistance is set by setting the apparent resistance R1 to RT <R1.
Image at the timing when copying and secondary transfer are performed simultaneously
The defect was prevented. [0005] SUMMARY OF THE INVENTION The above-described conventional transfer hand
In the stage, the primary transfer and the secondary transfer are performed simultaneously.
Image defect prevention is not satisfactory depending on the environment and paper type
There was a case. Specifically, the current that flows in the primary transfer
This phenomenon occurs when the current flowing in the secondary transfer is larger.
Became noticeable. The present invention seeks to solve the above problems.
The purpose is primary transfer, secondary transfer, simultaneous transfer
Image degradation at the time can be suppressedImage forming device
Is to provide. [0007] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
In the image forming apparatus of the present invention,Conductive layer of intermediate transfer belt
By applying a bias through the primary transfer member to
,Intermediate transfer of toner image formed on photoconductorOn the belt
Primary transfer toBias this toner image to the secondary transfer member.
Image formation to apply secondary transfer to recording medium by applying
Device,Applying a bias to the primary transfer member
The high voltage power supplyAt the time of primary transfer and secondary transfer simultaneous transfer,
Current sink that outputs negative current while outputting positive voltage
NohWorksIt is characterized by the following. [0008] The operation of the present invention will be described with reference to FIGS.
You. FIG. 4 is an equivalent circuit diagram at the time of primary transfer. V
1 is a primary transfer power supply voltage, R1 is a charged photoreceptor, resistance
When an intermediate transfer belt or the like having a layer is
The generated apparent resistance value, RT, is the primary transfer member or contact resistance.
The resistance value such as resistance, I1 is the current (primary
Current necessary for transfer). FIG. 5 shows that primary transfer and secondary transfer are performed simultaneously.
FIG. 9 is an equivalent circuit diagram in the case where V2 is the secondary transfer power supply voltage,
R2 is apparently generated by the secondary transfer member or recording medium
The resistance value, I2, of the current contributing to the secondary transfer
Required current). Here, the important point is the potential at point A.
If this potential fluctuates greatly, the optimal transfer electric field
A shift causes a primary transfer failure. To prevent this, RT <
By setting R1, I2 flows to the primary transfer power supply side
I made it. Specifically, the resistance value of the primary transfer member is 1 MΩ or less.
And IT is the primary transfer power supply current.
Can be expressed by IT = I1-I2. Therefore, I1 <I2.
Under the conditions, the primary transfer power supply current IT outputs a positive voltage.
Function (current sink function) that outputs a negative current
It is important. [0011] Embodiments of the present invention will be described below.
This will be described with reference to the drawings. FIG. 1 shows one example of an intermediate transfer unit according to the present invention.
FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an embodiment.
is there. First, an outline of the image forming apparatus will be described.
And then mainly on the intermediate transfer unit
I will explain. This image forming apparatus includes a yellow, cyan,
Using a magenta and black toner developer
Is a device that can form a full-color image. In FIG. 1, reference numeral 50 denotes a case of the apparatus main body.
The case 50 includes an exposure unit 60 and a paper feeding device.
Unit 70, photoconductor unit 100, developing unit 200,
Intermediate transfer unit 300, fixing unit 400, and
A control unit 80 for controlling the entire apparatus is provided.
Have been killed. The photoconductor unit 100 includes a photoconductor 110
And contact the outer peripheral surface of the photoconductor 110 to make the outer peripheral surface uniform.
A charging roller 120 as charging means for charging the toner;
And a leaning means 130. The developing unit 200 includes:
Developing unit 210Y for yellow, developing unit 210 for cyan
C, developing unit 210M for magenta, developing unit for black
210K. Each of these developing units 210Y, 21
0C, 210M, 210K have yellow inside
-, Cyan, magenta, and black toner
You. Further, the developing rollers 211Y, 211C, 2
11M, 211K, one of the developing units
Only the developing roller can come into contact with the photoconductor 110.
ing. The intermediate transfer unit 300 includes a driving roller 3
10 and a primary transfer roller (primary transfer backup roller)
B) 320, wrinkle removing roller 330, tension low
Roller 340, backup roller 350, and each roller
Endless intermediate transfer belt 360 stretched around the roller
And a screw which can be separated from the intermediate transfer belt 360.
Cleaning means 370. The secondary transfer to the backup roller 350
The rollers 380 are arranged to face each other. This secondary transfer row
The arm 380 is pivotally supported by a support shaft 381.
382, the arm 382 is rotatably supported.
By swinging by the operation of the cam 383, the intermediate transfer belt
It comes into contact with and separates from the tilt 360. The drive roller 310 has a gear 31 at its end.
1 (see FIG. 3) is fixed, and this gear 311
Meshes with the gear 144 (see FIG. 3) of the photoconductor unit 100
The peripheral speed is substantially the same as that of the photoconductor 110
, So that the intermediate transfer belt 360 is
It is driven to circulate at substantially the same peripheral speed as the optical body 110.
ing. When the intermediate transfer belt 360 is driven to circulate,
The primary transfer roller (primary transfer backup roller)
Between the photoconductor 110 and the photoconductor 110
Is transferred onto the intermediate transfer belt 360,
The toner image transferred onto the transfer belt 360 is secondarily transferred.
The recording medium S such as a sheet supplied between the rollers 380
Transcribed. The recording medium S is supplied from the sheet feeding device 70.
You. The paper feeding device 70 has a plurality of recording media S stacked thereon.
A tray 71 placed in a layer state and a pickup roller
72 and the recording medium S placed on the tray 71
A hopper 73 for urging toward the up-roller 72;
Make sure that one sheet of paper is fed by the backup roller 72
And a separation roller pair 74 that separates each roller. The recording medium S fed by the paper feeding device 70
Are a first conveying roller pair 91, a first paper sensor 91S,
2 transport roller pair 92, 2nd paper sensor 92S, gatero
The second transfer portion, ie, the intermediate transfer bell,
And is supplied between the transfer roller 360 and the secondary transfer roller 380.
After that, the fixing unit 400, the first discharge roller pair 94,
The paper is discharged onto the case 50 via the two paper discharge roller pairs 95. The fixing unit 400 has a fixing unit having a heat source.
Roller 410 and pressure roller 42 pressed against it
0. The operation of the entire image forming apparatus as described above is as follows.
It is as follows. (I) A host computer (not shown)
-Print command signal (image type) from a personal computer, etc.
Is input to the control unit 80, the photosensitive member 1
10, the developing roller of the developing unit 200, and the middle
The transfer belt 360 is driven to rotate. (Ii) The outer peripheral surface of the photoconductor 110 is charged low.
The toner is uniformly charged by the rubber 120. (Iii) of the uniformly charged photoconductor 110
On the outer peripheral surface, the first color (for example,
(Yellow) Selective exposure L according to image information
As a result, an electrostatic latent image for yellow is formed. (Iv) The first color (example)
Developing roller 211 of developing device 210Y for yellow)
Only Y contacts, thereby developing the electrostatic latent image.
The toner image of the first color (for example, yellow) is
10 is formed. (V) Toner formed on photoreceptor 110
The image is transferred to the primary transfer portion, that is, the photosensitive member 110 and the primary transfer portion.
(Primary transfer backup roller) 320
And a roller electrode (not shown) which is an example of a primary transfer member.
A bias is applied to the intermediate transfer belt 360
Is transferred to At this time, the cleaning means 370 and
And the secondary transfer roller 380 from the intermediate transfer belt 360
Separated. (Vi) Toe remaining on photoconductor 110
After the toner is removed by the cleaning means 130,
The photosensitive member 110 is neutralized by the neutralizing light L 'from the neutralizing means.
Is done. (Vii) Operations of (ii) to (vi) above
Is repeated as necessary. That is, the above print command
According to the content of the signal, the second color, the third color, the fourth color,
Is repeated according to the content of the print command signal.
The images are superimposed on the intermediate transfer belt 360
It is formed on the intermediary transfer belt 360. (Viii) Paper feeder at predetermined timing
70, the recording medium S is supplied.
2 Immediately before or after reaching the transfer section (in short,
At a desired position on the recording medium S, the intermediate transfer belt 360
(When the toner image is transferred)
380 is pressed against the intermediate transfer belt 360 and the intermediate transfer belt 360 is pressed.
Toner image on default 360 (basically full color image)
Is transferred onto the recording medium S. Cleaning means
370 contacts the intermediate transfer belt 360 and after the secondary transfer
The toner remaining on the intermediate transfer belt 360 is removed.
You. (Ix) The recording medium S is in the fixing unit 400
, The toner image is fixed on the recording medium S.
After that, the recording medium S passes through the discharge roller pairs 94 and 95, and
It is discharged onto the case 50. The outline of the image forming apparatus has been described above.
However, the following mainly describes details of the intermediate transfer unit 300.
Will be described. FIG. 2 mainly shows the intermediate transfer unit 300.
FIG. As described above, the intermediate transfer unit 300
Are a driving roller 310 and a primary transfer roller (primary transfer roller).
Backup roller) 320, wrinkle removing roller 330,
Tension roller 340 and backup roller 350
And an endless intermediate transfer stretched around these rollers
Belt 360 and roller electrode 6 as an example of a primary transfer member
00, and can be moved toward and away from the intermediate transfer belt 360.
Cleaning means 370;
Are attached to the frame 301 as shown in FIG.
Have been. The roller electrode 600 has a diameter of 10 mm and a width of 5 mm
About conductive elastic member located at the end of the intermediate transfer belt
Light contact with belt. This roller electrode 600 is unillustrated
The voltage is supplied from the primary transfer high voltage power supply shown in FIG. The frame 301 includes a pair of side plates (in FIG. 2,
(The side plate on the near side is omitted.)
Each of the above members and the like are attached between the plates. Conversely
For example, a pair of side plates are connected by the shaft of each of the above members.
Structure. Note that FIG.
For a pair of members to be specified,
Has been omitted. The drive roller 310 is driven by a shaft 312
It is rotatably supported by the frame 301 and has one end
The gear 311 (see FIG. 3) described above is fixed.
Gear 311 and the gear 144 of the photoconductor unit 100
By being engaged, substantially the same as the photoconductor 100
It is driven to rotate at a peripheral speed. Note that FIG.
500 is a drive motor, and its output shaft 501
The fixed pinion 510 is sensed through the reduction gear 520.
Meshes with a gear 144 provided at the end of the light body 110
As a result, the photoconductor 110 is driven to rotate.
Has become. The gear 311 includes an intermediate gear 520 and
And the photoreceptor unit 100 (FIG.
1) Drive gear 13 of toner transport screw 133
3b, so that the toner conveyance screen is
Queue 133 is driven to rotate. As shown in FIG. 2, a primary transfer roller (primary transfer roller)
Transfer backup roller) 320 has its shaft 321
The frame 301 can be rotated through a pair of bearing members 322.
Supported by Noh. The bearing member 322 is a frame
2 can be slid into a recess 303 provided in the
And can be moved up and down).
Between the member 322 and the frame 301 as urging means
A compression coil spring 324 is provided. Therefore, the primary transfer roller (primary transfer roller)
Backup roller) 320 has one end at one end of its shaft 321.
By being urged by the pair of compression coil springs 324,
Thus, pressure is applied to the photoconductor 110 via the intermediate transfer belt 360.
Touched. The wrinkle removing roller 330 is driven by its shaft 331.
Therefore, it is rotatably supported by the frame 301. The tension roller 340 has its shaft 341
Is rotated by a slot 304 provided in the frame 301.
Rollably and slidably supported. On axis 341
Are one end 3 of a pair of arms 342 at both ends.
42a is in contact. The arm 342 is pivoted about a shaft 343.
The frame 301 is swingably supported with respect to the frame 301.
A tension spring between the other end 342b and the frame 301
344 are provided. Therefore, the tension roller 340 is
With this tension spring 344, through the arm 342
The intermediate transfer belt 360 is always urged in the direction of stretching.
You. The backup roller 350 has its shaft 35
1 rotatably supported by the frame 301
You. The intermediate transfer belt 360 is connected to each of the rollers 3
Stretched around 10,320,330,340,350
In FIG. 2, the driving roller 310
Is circulated in the clockwise direction. The cleaning means 370 includes an intermediate transfer bell.
To remove residual toner remaining on the outer peripheral surface of
The fur brush 371 and the intermediate transfer belt 36
0 to scrape off the remaining toner on the outer peripheral surface
Lina blade 372 and these fur brushes 371
Or it was wiped off by the cleaner blade 372
As a transport means for transporting scraped toner
And a toner conveying screw 373 of
Each member is incorporated in the case 374. The lower part of the case 374 has a toner collection chamber 3
75 is formed in the toner collecting chamber 375.
The fur brush 371, the cleaner blade 372, and the
And a toner conveying screw 373. The fur brush 371 is located on the side of the case 374.
It is fixed to a shaft 371a penetrating the plate, and this shaft 371a
By being driven by driving means (not shown),
It is rotationally driven in the direction of the arrow in FIG. The cleaner blade 372 is attached to the mounting plate 372.
a attached to the case 374,
The end (lower end) contacts the outer peripheral surface of the intermediate transfer belt 360 to
The knives are scraped off. The toner conveying screw 373 is
A shaft 373a penetrating the side plate of 74 is driving means (not shown).
Rotated in the direction of the arrow in FIG. 2 by being driven by
Driven to collect the toner collected in the toner collection chamber 375.
Transfer the waste toner to a waste toner box (not shown).
You. The case 374 is provided on both side surfaces thereof.
The cylindrical portion 374a is connected to the frame 3 via a bearing member 376.
01 is rotatably supported. A hook 37 is provided on both sides of the lower end of the case 374.
7, the hook 377 and the frame
A tension spring 378 is provided between the extension spring 301 and the extension spring 301. Therefore, the tension spring 378
Therefore, the case 374 includes the fur brush 371 and the clear
Pressure on the intermediate transfer belt 360
It is always biased in the contact direction (clockwise),
A cam 55 is provided in the inter-transfer unit 300.
(See FIG. 1), the cam 55 contacts the lower end of the case 374.
Due to the contact, the rotation of the case 374 is restricted.
It is supposed to be. The cam 55 is driven by driving means (not shown).
When driven and in the position shown in FIG.
Rotate counterclockwise as indicated by the phantom line and
The intermediate transfer bell 371 and the cleaner blade 372
360. In FIG. 2, reference numeral 56 denotes a driving roller 310.
Provided in the image forming apparatus main body so as to face the
Position detection sensor (see Fig. 1).
This is for detecting the position of the object 360. The intermediate transfer unit 300 as described above is
It is detachable from the image forming apparatus main body. Further, in this embodiment, various devices are provided.
Has been or can be done, so
This will be described. <Regarding the Drive Roller 310> (1) The outer diameter of the drive roller 310 is the peripheral speed of the photoconductor 110
The peripheral speed of the intermediate transfer belt 360 is slightly
(Within the range). The peripheral speed of the photoconductor 110 and the
The peripheral speed of the intermediate transfer belt 360 to which the toner image is transferred
Are desirably completely identical. However, the outer diameter of the photoconductor 110 and the
Since the outer diameter of the drive roller 310 has a tolerance,
It is impossible to match each other completely. like this
In a situation where the drive roller 310 is wound around
The peripheral speed of the intermediate transfer belt 360 is the peripheral speed of the photoconductor 110.
If the speed is slightly slower than the
Transfer roller (primary transfer backup roller) 320
The pressing position (primary transfer position T1) and the driving roller 310
Between the intermediate transfer belt 360 and
The force to be applied will work even though it is extremely small,
State of the intermediate transfer belt 360 at the primary transfer position T1
Becomes unstable. Therefore, in this embodiment, the driving roller
Intermediate transfer of the outer diameter of 310 to the peripheral speed of photoconductor 110
The peripheral speed of the belt 360 is slightly increased (within tolerance).
It was configured so that: With this configuration, the photosensitive member 110 and one
Next transfer roller (primary transfer backup roller) 320
(The primary transfer position T1) and the drive roller 310
The intermediate transfer belt 360 is slightly
However, since it is always in tension, the primary transfer position T1
The state of the intermediate transfer belt 360 is stabilized. The amount of run-out on the outer peripheral surface of the drive roller 310
Was set to ± 0.05 mm or less. (2) The period of the intermediate transfer belt 360 is driven
The roller 310 is configured to be an integral multiple of the period. With this configuration, the driving roller 310
Of the intermediate transfer belt caused by runout of the shaft or outer peripheral surface of
Between the toner images of each color superimposed on the
The amount of displacement can be reduced. Specifically, the above ratio is set to 5: 1.
Was. (3) The cycle of the intermediate transfer belt 360 is photosensitive
It was configured to be an integral multiple of the period of the body 110. With this configuration, the shaft of the photosensitive member 110
Or, an intermediate transfer belt caused by runout of the outer peripheral surface
360 between the toner images of the respective colors superimposed on each other
The amount of displacement can be reduced. Specifically, the above ratio is set to 2: 1.
Was. (4) Intermediate transfer to drive roller 310
The wrap angle of the belt 360 is 90 ° or more, and
Is larger than the winding angle with respect to the roller. With this configuration, the driving roller 310
Even if the coefficient of friction between the belt and the intermediate transfer belt 360 is small,
Or stable even if it becomes smaller due to long-term use
The transfer belt 360 can be driven. Specifically, the wrapping angle is 15
It was about 1 mm. The outer peripheral surface of the drive roller 310 is
A urethane coat was applied to increase the friction coefficient. <Regarding Backup Roller 350>
Pressure contact between backup roller 350 and secondary transfer roller 380
Part, that is, in the secondary transfer part T2 (see FIG. 2).
The method of separating the intermediary transfer belt 360 and the recording medium S depends on the curvature.
The separation method is adopted, and the diameter of the backup roller 350 is φ3
5 mm or less, intermediate rotation for backup roller 350
The winding angle of the copying belt 360 was set to 90 ° or more. With this configuration, the recording medium
To ensure that the body S is separated from the intermediate transfer belt 360
become. More preferably, the backup row
The diameter of the roller 350 is φ30mm or less, backup roller
The winding angle of the intermediate transfer belt 360 with respect to
05 ° or more. Specifically, the diameter is φ30 mm,
The hanging angle was 109 °. Further, the surface resistance of the intermediate transfer belt 360
Is 10¹²It is desirable to be Ω or less. <Regarding the Cleaning Means 370> (1) Replace the tension roller 340 with a backup roller
Cleaning means 3 in the horizontal direction
Deflected (closed) to the 70 side, fur brush 371 and middle
The toner collecting chamber 3 is located below the contact portion with the inter-transfer belt 360.
75 is configured to be partially open. With this configuration, the fur brush 37
1 is transferred to the toner collecting chamber 37.
5 to be easily collected. More preferably, tension roller 340
Intermediate transfer belt between the
The angle θ between the tilt 360 and the vertical line V (that is, the tension
Roller 340 and backup roller 350
Angle between the line and the vertical line V) is 10 ° or more,
Preferably, it is 15 mm or more. With this configuration, the fur brush 37
1 is transferred to the toner collecting chamber 37.
5 makes it easier to be collected reliably,
The transfer means 370 separates from the intermediate transfer belt 360
Falling toner is also easily collected in the toner collection chamber 375.
Become. (2) Intermediate transfer of cleaning means 370
Tension means for receiving urging force against belt 360
The roller 340 was also used. With this configuration, manufacturing costs can be reduced.
Can be reduced. Also, separately from this
It is not necessary to provide a roller, and the number of rollers is reduced.
Each roller has a large wrap angle because it can be eliminated
Will be able to take <Regarding Wrinkle Removal Roller 330>
Roller 330 with respect to the primary transfer position T1,
It is arranged closely on the upstream side in the circulation direction of 360,
Winding of the intermediate transfer belt 360 around the take-up roller 330
The angle of inclination was set to 10 ° or more. With this configuration, the tension
Intermediate rotation between the transfer roller 340 and the wrinkle removing roller 330.
Wrinkles generated on the photo belt 360 (from the wrinkle removing roller 330
The wavy state when looking in the direction of the cushion roller 340)
Removed by wrinkle removing roller 330, and at primary transfer position T1
The state of the intermediate transfer belt 360 to be smooth
Can be. More preferably, the wrinkle removing roller 33
The winding angle of the intermediate transfer belt 360 with respect to 0 is 15 °.
Above. Specifically, it was 17.6 °. In place of the wrinkle removing roller 330, an intermediate
To change the traveling direction of the transfer belt 360 by 10 ° or more
A step (for example, a guide plate or the like) may be provided. <Regarding the Primary Transfer Position T1> (1) At the primary transfer position T1, the intermediate transfer belt 36
0 is linearly stretched tangentially to the photoconductor 110
As described above, the drive roller 310 and the primary transfer roller (primary transfer
Backup roller) 320 and wrinkle removing roller 33
0 was placed. With such a configuration, the bell
The transfer nip can be stabilized regardless of tension.
Wear. If the primary transfer roller (primary transfer backup roller)
Roller) 320 around the intermediate transfer belt 360,
When the primary transfer position T1 is formed at the winding portion
Then, the fluctuation of the tension of the intermediate transfer belt 360 is changed to the primary transfer.
Although the influence on the position T1 increases, the intermediate transfer belt
360 is the primary transfer roller (primary transfer backup roller)
B) Tangential direction to photoconductor 110 without winding around 320
The above effect can be reduced by
Can be. (2) Move the primary transfer position T1 to the drive roller 31
It was arranged close to 0. The position of the primary transfer position T1 and the drive roller 310
When the distance between them increases, the intermediate transfer bell
360, the amount of expansion and contraction becomes large, and the primary transfer position T1
Running speed of the intermediate transfer belt 360 at
You. Therefore, in this embodiment, the primary transfer position
The arrangement T1 is arranged close to the drive roller 310.
Thus, the intermediate transfer bell at the primary transfer position T1
The stabilization of the traveling speed of the vehicle 360 is achieved. The movement between the primary transfer position T1 and the drive roller 310
The distance L1 (see FIG. 2) is desirably 40 mm or less.
Below, more desirably, 35 mm or less. Specifically
Was about 30.5 mm. (3) From the wrinkle removing roller 330 to the driving roller
The length of the linear portion of the intermediate transfer belt 360 up to 310
0.25 or less in aspect ratio, more preferably 0.15
The following is assumed. In order to more effectively suppress the influence of the wrinkles,
It is. [0098] Specifically, the length of the linear portion is set to 5
It was about 5.5 mm. <Regarding Position Detection> As described above, the position
Move the detection sensor 56 to a position facing the drive roller 310.
The intermediate transfer belt 360 on the drive roller 310.
The position is detected. As a result, the running of the intermediate transfer belt 360 is
The line cycle can be accurately detected. The position detecting sensor 56 is a reflection type optical sensor.
The position detection sensor is provided on the intermediate transfer belt 360.
The mark to be detected by the
I did. The position detecting sensor is a transmission type optical sensor,
The holes to be detected by this are set in the intermediate transfer belt 360.
When the hole is opened, stress concentrates on the hole and its shape is deformed.
May not be able to perform accurate detection.
However, in this embodiment, the position detection sensor 56
Is a reflective optical sensor, which should be detected by
The mark was provided by printing on the intermediate transfer belt 360
Therefore, the running cycle of the intermediate transfer belt 360 can be accurately detected.
Can be <Stretching structure of intermediate transfer belt 360, etc.
The intermediate transfer belt 360 is stretched in the primary transfer position.
Intermediate transfer belt between the position T1 and the secondary transfer position T2
The length above 360 is greater than the horizontal length of A4 size paper
Between the secondary transfer position T2 and the primary transfer position T1
The length on the intermediate transfer belt 360 is also A4 size.
Paper length longer than the horizontal length. That is, like this
Stretch the intermediate transfer belt 360 so that the length becomes
Was. With such a configuration, the A4 size
When printing continuously on paper, the secondary transfer roller 3
The timing at which the roller 80 contacts the intermediate transfer belt 360
Set between papers, ie secondary transfer during primary transfer
The roller 380 can be prevented from abutting. During the primary transfer, the secondary transfer roller 380 is
When it comes into contact with the transfer belt 360,
The image may be disturbed by the transfer,
The configuration prevents such a situation.
Can be. <Regarding the Cleaning Means 370> (1) The cleaner blade 372 is made of urethane rubber.
The free length is about 8 mm, the thickness is about 3 mm,
And the holder angle (with no load)
Between the blade and the tangent of the roller at its abutment position
Angle) of about 20 °, contact with the intermediate transfer belt 360
The pressure was about 45 gf / cm. With such a configuration, the toner slips through.
And cleaning by blade vibration and turning up
Failure can be prevented. (2) Separately from the case 374, the waste toner bottle
A box was set up. With this configuration, the case 374
Since a large amount of waste toner does not accumulate,
Load when swinging the base 374, and after swinging
It is possible to reduce the fluctuation of the force acting on the case 374
The intermediate transfer belt of the cleaner blade 372 as a result.
The contact pressure against the bolt 360 can be stabilized.
You. (3) Shaft 3 of Toner Conveying Screw 373
73a (see FIG. 2) was set as the center of rotation of the case. With this configuration, other fixing members, such as an example,
For example, the waste toner outlet of the case 374 and the waste toner box
The relative position of the toner with the toner
Becomes easier. (4) The cam 55 is a SIN cam. With this configuration, the intermediate rotation
The impact on the photo belt 360 can be reduced.
You. <Regarding Patch Sensing> Patch Sensitivity
In other words, the toner amount detection during test printing
The intermediate transfer belt 360 on the roller 310
Was. With this configuration, the winding
It can be performed in a place with a large angle and stable speed.
Wear. <Regarding Bead> The bead is an intermediate transfer bell.
Ridges provided along the circulation direction on the back of
This ridge is formed on the roller around which the belt is wound.
The belt is engaged by engaging the
To define the position (in the axial direction of the roller)
Things. This bead need not always be provided.
That is, in the embodiment shown in FIG.
However, if provided, the following configuration shall be used.
You. (1) Silicon rubber is used as a bead
The thickness (projection height) is about 1.5 mm, and the width is
It is about 4 mm. (2) Coefficient of friction of the bead with respect to the regulating groove
Is the base of the intermediate transfer belt 360 for any of the rollers.
It should be smaller than the friction coefficient of the material. With this configuration, the beads
Tension gradient in the belt axis direction due to the friction force between the belt and the regulating groove
Can be reduced. The intermediate transfer belt 36 with respect to the rollers
The coefficient of friction of the base material of 0 is about 0.4. (3) The elastic strength of the bead is E = 2.0 to
It is set to about 8.0 MPa. [0123] If it is too soft, the thrust
Stress is concentrated in one place, which is the narrow area of the bead joint
Because they concentrate on On the other hand, if the belt is too hard,
This is because the involvement of the bead increases. More preferably, the elastic strength of the bead
Is t1: belt thickness t2: Bead thickness E1: Belt Young's modulus (~ 4.0 × 10^Three[MPa]) And when 1.0 to (t1 / t2) 2E1 [MPa]. (4) The bead regulating groove is located at the primary transfer position T1.
On a roller that is not adjacent to. With such a configuration, the bead, the restriction groove,
Fluctuation of the intermediate transfer belt 360 due to contact of
Therefore, the images are superimposed on the intermediate transfer belt 360.
Position difference between each color toner image
You. For example, the bead regulating groove is
Attach a stepped flange to the end of the
And (5) The width of the regulating groove is larger than the bead width.
Slightly larger, with margin for straightness of bead attachment
Add. For example, if the bead width is about 4 mm,
The width of the restriction groove is about 4.2 mm. <Replacement and Handling of Intermediate Transfer Unit 300
About> (1) When the intermediate transfer unit 300 is placed on a desk or the like
In addition, a structure in which the intermediate transfer belt 360 does not contact the desk top surface or the like
To prevent damage to the intermediate transfer belt 360 and adhesion of foreign matter
I do. (2) Place the intermediate transfer unit 300 on a desk or the like
When placed, the drive transmission unit (e.g., gear 311 etc.)
As a structure that does not contact the top surface, etc.
Prevent damage. (3) The electrode portion of the intermediate transfer unit 300 is
The structure provided on the opposite side of the drive transmission section
And to prevent contact failure. (4) Do not mount the intermediate transfer unit 300
The photoreceptor unit 100 cannot be mounted
The structure prevents incorrect mounting. (5) Intermediate transfer of waste toner box capacity
In accordance with the life of the belt 360, the intermediate transfer unit 30
And the waste toner box can be replaced together with
Improve handling. <Regarding the sequence> (1) Intermediate transfer base serving as a reference for exposure writing timing
When detecting the position of the default 360, the primary transfer
Bias, that is, the primary transfer
A bias is applied. In this way, the position of each of the four colors
From the detection to the primary transfer at the primary transfer position T1
The load on the intermediary transfer belt 360 becomes almost equal,
Each color toner superimposed on the photo belt 360
-Positional deviation between images (this deviation is called registration deviation)
Can be suppressed. (2) When the intermediate transfer belt 360 is stopped
The position of the position detection mark is different from the primary transfer position T1.
So that it is on the upstream side. For example, in FIG.
In the position shown by. By doing so, the intermediate transfer belt 360
Transfer bell by bias application at the beginning of rotation
To perform position detection when the tension of G360 is unstable
To avoid resist deviation due to period shift
Can be. <Frame 30 of Intermediate Transfer Unit 300
Regarding 1> The side plate of the frame 301 is made of an insulating member
To apply a bias to the roller.
No need to insulate the shaft (and / or bearing member)
I do. Further, ABS resin is used as an insulating member.
In this way, the coefficient of thermal expansion of the frame 301 can be
Approximately the same as that of belt 360,
The misalignment can be prevented. [0142] Hereinafter, more specific examples will be described.
You. The following description mainly describes the transfer process.
It is a thing. (1) The intermediate transfer belt 360 is formed by AL vapor deposition.
Urethane-based PE
Coating with dispersed FT particles and tin oxide as a conductive agent
Material is applied and both ends are bonded by ultrasonic fusion to form an endless intermediate
The transfer belt 360 is configured. The step caused by the adhesion at both ends is 50 steps.
μm or less, more preferably 30 μm or less. Paint
Young's modulus is 1.5 × 10^Fourkgf / cm^TwoDegree.
The surface resistance of the paint is 10⁸-10¹²Ω / □, table
The surface roughness is Rmax 1 μm (more preferably 0.7 μm).
m) The electrode configuration consists of a conductive layer on the AL surface at the edge.
Is printed, and the via is applied from the roller electrode 600 (1 MΩ or less).
In this configuration, the voltage is applied. The primary transfer member is the roller
Other than poles, brushes, blades, etc. may be used.
It is important that it is resistance. With the above configuration, the transfer efficiency and the cleaning
Ning performance can be improved. (2) The high voltage power supply is
The current transfer type constant voltage control is used, and the secondary transfer ends.
Up to the primary transfer voltage. The primary transfer roller (primary transfer back-up
Roller), this is called the backup roller
Function only. The above electrode configuration and power supply configuration
When the secondary transfer current is larger than the primary transfer current,
Even at the same time, image quality degradation due to interference during simultaneous transfer can be suppressed.
it can. Table 1 shows the experimental results. [0151] [Table 1] The difference between the comparative example and the embodiment is the difference only in the high voltage power supply.
is there. Conventionally, the secondary transfer current is one more than the primary transfer current.
When there was more than 0 μA, the image quality was remarkably deteriorated.
High quality images can be obtained regardless of environment and paper type
became. <To stabilize the primary transfer efficiency> (1) The set value of the primary transfer high voltage power supply was 500V. one
The current flowing during the next transfer was about 20 to 50 μA. The primary transfer roller (primary transfer back-up
Roller) 320 is a shaft having a diameter of 12 mm and an outer diameter of 22 m.
m and a width of 358 mm. The material is urethane low
And the hardness is set to 45 ± 5 °.
The pressure contact load is 1.0 to 3.5 kg (more preferably, 2.
5 kg). That is, 28 to 98 g / cm (more
(Preferably about 70 g / cm). In addition, the ranges of hardness and load as described above
Then, it is possible to prevent a so-called hollow hole. (2) Regarding the amount of the external additive of the toner to be used,
The amount of the external additive having a large particle size (primary particle size 40 nm)
0.5 to 4.0 wt% (more preferably about 0.7 wt%
Degree) and the amount of the external additive having a small particle diameter (primary particle diameter 14 nm)
From 1.5 to 4.0 wt% (more preferably 2.0 wt%
Degree). The external additive having a large particle diameter is mainly used for the durability and stability of the toner.
Is necessary to improve the properties (concentration stability).
The more it is from the point, the better, but more than 4.0 wt%
Causes poor toner fluidity,
This is not preferred. The external additive having a small particle size is mainly used for converting rough paper.
It is necessary to improve the photographic performance, and from this point
The more it is, the better, but if it exceeds 4.0 wt%, suspended silica
Triggers the photoconductor 110 and the intermediate transfer belt 360
Is unfavorable because filming is likely to occur. <To stabilize the secondary transfer efficiency> (1) Impedance of secondary transfer (for secondary transfer not shown)
When the ratio of the output voltage to the output current of the power supply is large (about 20)
Is constant current and impedance is small
(When the voltage is approximately 20 MΩ or less), the constant voltage control is performed.
A high voltage power supply was used. The constant current setting is 30 μA, and the constant voltage
The fixed value was 600 V. As a result, the paper type, environment, and material
Good transfer is achieved even if the resistance varies
I did it. (2) The surface resistance of the intermediate transfer belt 360 is
10⁸-10¹²Ω / □, volume resistivity 10⁸-10¹²Ωc
m. The secondary transfer roller 380 has a diameter of 15 m.
The shaft of m had an outer diameter of 25 mm and a width of 332 mm.
Made of conductive material with ionic conductive agent such as lithium perchlorate
Roller with a resistance of 10⁶~ 10⁸Ω and hard
The degree shall be 60 ± 5 °, and
Pressing pressure is 5.0 to 9.0 kg (more preferably, 7.0 to 9.0 kg).
0 kg). That is, 150 to 270 g / cm (
More preferably, about 210 g / cm). With the above range of the resistance value, 40
Transfer can be performed at 00 V or less and 200 μA or less. The backup roller 350 is grounded.
And a bell as an insulating member
G has the effect of removing electricity from the back surface (PET surface). (3) Regarding the amount of the external additive of the toner to be used,
The amount of the external additive having a large particle size is 0.5 to 4.0 wt% (
More preferably about 0.7 wt%), and a small particle size external additive.
Of 1.5 to 4.0 wt% (more preferably 2.0 w
t%). The reason is as described above. Under the above conditions, at the time of primary and secondary simultaneous transfer
To prevent image degradation due to interference from
Can be minimized. <Prevention of Back Surface Dirt of Recording Medium S such as Paper
The secondary transfer roller 380 is connected to the intermediate transfer belt 36.
0, and between toner and paper,
To the intermediate transfer belt 360 (0 to −60).
(Approximately 0 V). With this configuration, the secondary transfer roller 3
80, the amount of toner adhering to the recording medium S is reduced, and
Is reduced. <Good roll even on rough paper (bond paper)
In order to make a photo> (1) The secondary transfer roller 380 has a hardness of 60 ± 5 °.
And the pressure contact load on the backup roller 350 is
5.0-9.0kg (more preferably about 7.0kg)
And (2) Regarding the amount of the external additive of the toner to be used,
The amount of the external additive having a large particle size is 0.5 to 4.0 wt% (
More preferably about 0.7 wt%), and a small particle size external additive.
Of 1.5 to 4.0 wt% (more preferably 2.0 w
t%). The toner having a particle size of about 7 μm
A high concentration pigment toner was used. (3) Amount of toner before secondary transfer, that is,
The amount of toner on the intermediate transfer belt 360 is set to 1.5 mg / c
m^TwoThe following was set. With the above arrangements (1) to (3),
Is good for rough paper such as Ninabond paper
A transfer state can be obtained. That is, the secondary transfer roller 380 is
High hardness and high load applied to it
Therefore, the paper surface can be brought into close contact with the toner,
Even if an electric field is formed, transfer failure due to discharge is suppressed.
The transport state of the sheet is also stabilized by the high load. Furthermore, the toner amount before the secondary transfer is
To increase toner transfer efficiency
be able to. <In order to prevent voids> (1) The material of the intermediate transfer belt 360 is a conductive agent.
ETFE or fluorine with carbon black dispersed
Aluminum deposited PET coated with urethane paint containing fine particles
Or dispersed carbon black etc. as conductive agent
Polyimide was used. The material of the photoconductor 110 is made of polycarbonate.
Nate. (2) Primary transfer roller (primary transfer backup
Roller) 320 has a hardness of 45 ± 5 °
The pressing load on the optical body 110 is 1.0 to 3.5 kg.
Was. (3) The hardness of the secondary transfer roller 380 is
Is set to 60 ± 5 °, and
The pressure contact load was 5.0 to 9.0 kg. (4) Regarding the amount of the external additive of the toner to be used,
The amount of the external additive having a large particle size is 0.5 to 4.0 wt% (
More preferably about 0.7 wt%), and a small particle size external additive.
Of 1.5 to 4.0 wt% (more preferably 2.0 w
t%). Regarding the fluidity, A.I. D 0.35
g / cc. With the above configuration, the following operation can be achieved.
The effect is obtained. That is, in the primary transfer section, the photosensitive member
When the transfer condition from 110 to the intermediate transfer belt 360 is low
Density, low load, and high fluidity
Is prevented. In the secondary transfer section, the intermediate transfer belt 3
Although the transfer conditions from 60 are high hardness and high load,
The material of the intermediate transfer belt 360 is fluorine-based,
High fluidity toner prevents hollow holes
Is stopped. <To reduce scattering (scatter of toner)
> (1) Near the upstream side of the primary transfer position (primary transfer portion) T1
A wrinkle removing roller 330 was provided. (2) Regarding the amount of the external additive of the toner to be used,
The amount of the external additive having a large particle size is 0.5 to 4.0 wt% (
More preferably about 0.7 wt%), and a small particle size external additive.
Of 1.5 to 4.0 wt% (more preferably 2.0 w
t%). Regarding the fluidity, A.I. D 0.35
g / cc, and the charge amount should be -10 μC / g or more.
Was. (3) Surface roughness of the intermediate transfer belt 360
Is Rmax 1 μm (more preferably 0.7 μm) or less
And The surface resistance of the intermediate transfer belt 360 is
10⁸-10¹²Ω / □, volume resistivity 10⁸-10¹²Ωc
m. With the above configuration, the following operation is performed.
Effect is obtained. That is, in the primary transfer portion, wrinkle removal is performed.
Roller 330 reduces wrinkles of intermediate transfer belt 360
And scattering is suppressed. In the secondary transfer section, the intermediate transfer belt 3
60 is conveyed stably and scattering is suppressed.
You. The embodiments and examples of the present invention have been described above.
Although the present invention has been described, the present invention is not limited to the above embodiment or embodiment.
The present invention is not limited to the examples, but falls within the scope of the present invention.
Can be appropriately modified. [0196] According to the present invention,Image forming deviceAccording to the high piezoelectric
Optimized source control and optimized primary transfer member resistance
Therefore, primary transfer and secondary transfer simultaneous transfer regardless of environment and paper type
Image degradation at the time can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of an image forming apparatus using an embodiment of an intermediate transfer unit according to the present invention. FIG. 2 is a partially omitted side view mainly showing an intermediate transfer unit 300; FIG. 3 is a diagram showing a main part of a gear train. FIG. 4 is a diagram illustrating the operation of the present invention. FIG. 5 is a diagram illustrating the operation of the present invention. [Description of Signs] 110 Photoconductor T1 Primary transfer position T2 Secondary transfer position 310 Drive roller 360 Intermediate transfer belt 600 Roller electrode

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yama ▲ saki ▼ Toshihiko 3-3-5 Yamato, Suwa-shi, Nagano Inside Seiko Epson Corporation (72) Inventor Tatsuro Osawa 3-3-1 Yamato, Suwa-shi, Nagano No. 5 Seiko Epson Corporation (72) Inventor Taihei Ishiwata 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation (56) References JP-A-8-194389 (JP, A) Hei 8-197390 (JP, A) JP-A Hei 8-160756 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 15/01 114

Claims (1)

(57) [Claim 1] A primary transfer member is provided on a conductive layer of an intermediate transfer belt.
The toner image formed on the photoreceptor is primarily transferred onto an intermediate transfer belt by applying a bias through the intermediate transfer belt, and the toner image is secondarily transferred onto a recording medium by applying a bias to a secondary transfer member. an image forming apparatus, high-voltage power supply for applying a bias to said primary transfer member is a primary rolling
An image forming apparatus characterized in that a current sinking function of outputting a negative voltage while outputting a positive voltage works at the time of simultaneous transfer of image transfer and secondary transfer .