JPH096150A - Transferring/carrying device - Google Patents

Abstract

PURPOSE: To prevent staining on the rear side of a transfer paper due to the lowering of the cleaning ability for a transfer belt surface, to prevent defective transfer due to change in the resistance value of the transfer belt, and to obtain a stable satisfactory transfer process irrespective of the lapse of time and environmental change. CONSTITUTION: The transferring/carrying device 1 is provided with a transfer belt 6 which comes into contact with an image carrier 3, a transfer bias roller 11 for impressing a transfer voltage, a means 16a for cleaning the surface of the transfer belt 6 and an attaching/detaching means 9 for attaching/detaching the transfer belt 6 to/from the image carrier 3, and the transfer belt 6 is driven in a state where the transfer belt 6 is separated from the image carrier 3 by the means 9, and a voltage whose polarity is the same as that used at transfer is impressed on the transfer bias roller 11, simultaneously, the surface of the transfer belt 6 is cleaned by the cleaning means 16a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / conveying device used in an image forming apparatus such as a copying machine or a printer and transferring a toner image on an image carrier by a transfer belt.

[0002]

2. Description of the Related Art Conventionally, a contact type transfer / conveying apparatus is known in which a transfer bias voltage is applied to a transfer belt to directly contact a transfer sheet with a toner image on a photosensitive member to transfer the toner image. This contact type transfer / conveyance device has advantages such as less ozone generation, smaller power supply capacity, and better separation / conveyance performance of transfer paper, as compared with other conventional transfer systems. Further, the transfer belt used in this apparatus is made of an elastic body so that a predetermined tension is generated when the transfer belt is mounted.

[0003]

However, in the above-mentioned conventional transfer / conveying apparatus, how to coat a material having a low friction coefficient, that is, a hard material, on the transfer belt made of an elastic material having elongation. Is a problem.
A material having a low coefficient of friction has a lower coefficient of friction as it is harder and exhibits its original properties. However, when the material is coated on an elastic transfer belt, the tension of the belt becomes high and the elongation becomes poor. If you try to forcibly stretch the belt in this state, cracks will form in the coating layer on the belt surface, toner will enter this crack, and you will not be able to scrape it with a cleaning blade, brush, etc., and there will be poor cleaning on the transfer belt surface. appear. This cleaning failure on the surface of the transfer belt has a problem that the transfer surface of the transfer paper conveyed on the transfer belt and the opposite side are contaminated to cause "dirt on the back of the transfer paper".

Further, in the contact type method, the transferability is changed due to the difference in the resistance value of the transfer belt. Particularly, when the resistance is low, white spots in the image may occur due to discharge between the transfer paper and the photoconductor, The current flows too much and exceeds the capacity of the high-voltage power supply, and a predetermined transfer output cannot be obtained, which easily causes a transfer failure. In particular, a transfer belt that performs transfer using contact electrodes uses a medium resistance region (10 ⁶ to 10 ¹² ), but it is difficult to manufacture a transfer belt that has uniform resistance over the entire circumference, and variations in resistance may occur in the circumference. If it occurs inside, the above-mentioned transfer failure is likely to occur.

On the contrary, even if the resistance is partially increased in the belt, the response of the power supply is not in time, and similarly, the transfer failure is likely to occur. For the transfer belt in the medium resistance area, a material with a small resistance change is selected, but the resistance change still occurs depending on the condition of the belt (time, temperature and humidity) and the mounting condition (presence or absence of extension, ambient temperature). However, there is a problem in that transfer is defective due to such changes. Therefore, the present invention solves the above-mentioned conventional problems, and can prevent the back stain of the transfer paper due to the deterioration of the cleaning property of the transfer belt surface and the transfer failure due to the change in the resistance value of the transfer belt, Transfer that can obtain a stable and good transfer process that is not affected by changes in time or the environment
An object is to provide a carrier device.

[0006]

According to a first aspect of the present invention, there is provided a transfer belt which is in contact with an image carrier and is supported by a drive roller and a driven roller, and a predetermined transfer belt. A transfer bias roller for applying a transfer voltage,
In a transfer / conveyance device provided with cleaning means for cleaning the surface of the transfer belt and contacting / separating means for contacting / separating the transfer belt with respect to the image carrier, the transfer belt is provided with the image carrier by the contacting / separating means. That is, the transfer belt is driven by the drive roller while being separated from the body, and a voltage having the same polarity as that at the time of transfer is applied to the transfer bias roller, and at the same time, the cleaning means cleans the transfer belt surface. .

According to a second aspect of the present invention, in the transfer / conveyance device, the transfer roller is driven by the drive roller while the transfer belt is separated from the image carrier by the contacting / separating unit, and the transfer bias is generated. Applying a voltage having a polarity opposite to that at the time of transfer to the roller, and simultaneously cleaning the transfer belt surface by the cleaning means;
According to a third aspect of the present invention, a contact plate that comes into contact with the surface or the inner surface of the transfer belt and a current detection unit that detects a current flowing from the contact plate are provided, and the transfer belt is separated from the image carrier. In this state, the transfer belt is driven by the drive roller, a predetermined voltage is applied to the transfer bias roller, the current is detected by the current detecting means, and the transfer voltage is determined from the detection result. .

According to a fourth aspect of the present invention, the transfer bias roller is supported by a pressing unit that urges the roller in a direction perpendicular to the transfer belt surface.
Further, in claim 5, the operation timings of the claims 1, 2 and 3 are set to the rising time when the power of the copying machine main body is turned on, and in the claim 6, the operation timings of the claims 1, 2 and 3. The operation timings of 3 and 3 are set to the end of the repeat during the copy operation. Further, in claim 7, the operation timings of the above claims 1, 2, and 3 are the timing immediately after the recovery when a jam occurs during the copy operation. That is what I did.

[0009]

Therefore, in the first aspect, the transfer belt is driven by the driving roller while the transfer belt is separated from the image carrier by the contacting / separating means, and the transfer bias roller is
By applying a voltage of the same polarity as during transfer, the toner of the same polarity as the transfer voltage existing on the transfer belt electrostatically repels, weakening the attraction to the transfer belt surface, and the cleaning means transfers the transfer belt surface. The cleaning efficiency of

According to the second aspect of the invention, the transfer belt is driven by the drive roller while the transfer belt is separated from the image carrier by the contacting / separating means, and the transfer bias roller is applied with a voltage having a polarity opposite to that at the time of transfer. By applying, the toner having the opposite polarity to the transfer voltage existing on the transfer belt is electrostatically repulsed, the attracting force on the transfer belt surface is weakened, and the cleaning efficiency of the transfer belt surface by the cleaning unit is increased. According to a third aspect of the present invention, in a state where the transfer belt is separated from the image carrier, the transfer belt is driven by the drive roller, and a predetermined voltage is applied to the transfer bias roller to detect a current detecting unit. The transfer voltage is applied according to the electric resistance value of the transfer belt by detecting the current by the method and determining the transfer voltage from the detection result.

Further, in the present invention, since the transfer bias roller is biased by the pressing means in the direction perpendicular to the transfer belt surface, the transfer bias roller is transferred regardless of the position change of the transfer belt by the contacting / separating means. The state of being in contact with the belt is maintained. As a result, the actions of claims 1, 2, and 3 can be performed even when the transfer belt is separated from the image carrier. Further, in claim 5, by performing the operations of claims 1, 2 and 3 during the rising time when the power of the copying machine main body is turned on, the productivity of copying can be reduced without lowering the productivity. , And 3 are possible. Further, in claim 6, by performing the operations of the claims 1, 2 and 3 at the end of the repeat during the copying operation, there is the same effect as the claim 5. Further, in claim 7, by performing the operations of claims 1, 2 and 3 immediately after the restoration in the case of jamming during the copy operation, the same effect as in claim 5 can be obtained.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the photosensitive drum 3 which is an image carrier
A separation claw 18 for the transfer paper P, a cleaning device (not shown), a charge eliminating lamp, an exposing means, a developing device, a pre-transfer charge eliminating lamp (PTL) 15 and a transfer belt unit 2 are arranged in close proximity to or in contact with. The transfer belt 6 of the transfer belt unit 2 is an endless belt, has a two-layer structure including an inner layer 6a and a surface layer 6b as shown in FIG. 2, and is driven as shown in FIG. The roller 5, the both ends 4a thereof are supported by the driven roller 4 formed in a tapered shape, and the transfer bias roller 11 for applying the transfer bias voltage to the inner surface side of the roller 5 and the contact plate 13 for flowing the current to the ground are in contact with each other. It is arranged. The transfer bias roller 11 has a high-voltage power supply 12, and the contact plate 13 has a transfer control plate 1.
4 are connected to each other, and the high voltage power source 12 and the transfer control plate 14 are connected.
Is also electrically connected.

On the transfer belt 6, the surface resistance of the surface layer 6b is 1 × 10 ⁹ to 1 × 10 ¹² Ω when an electric resistance of DC 100 V is measured according to JIS K6911.
And the electric resistance of the inner layer 6a is 1 × 10 ⁷ to 1 × 10 ⁹ Ω,
The volume resistivity thereof is 5 × 10 ^{8 to} 5 × 10 ¹⁰ Ω · cm. The drive roller 5 is a transfer belt 6 when driven.
A material such as EDPM rubber, chloroprene rubber, or silicone rubber is selected because of its function of enhancing the gripping force against.

In the transfer belt 6, the support 7 is pushed by the push-up lever 9 connected to the DC solenoid 8 which is operated by a signal from the control plate 8a.
The drive roller 5 rotates about a support shaft 5a as a fulcrum and comes into contact with the photosensitive drum 3. Further, a cleaning blade 16a that contacts the drive roller 5 via the transfer belt 6 and cleans the transfer belt 6 is disposed, and a toner receiver 16 having a recovery coil 16b built therein is disposed below the cleaning blade 16a. The DC solenoid 8 and the lever 9 constitute a contacting / separating means for contacting / separating the transfer belt 6 with respect to the photosensitive drum 3. The transfer belt unit 2, the transfer belt 6, the driving roller 5, the driven roller 4, the support 7, the transfer bias roller 11, the ground plate 13, the cleaning blade 16a, and the like constitute the transfer belt unit 2.
As shown in FIG. 4, the main substrate 1 of the transfer / transport apparatus 1 is
It is detachably supported with respect to a.

Further, on the transport path of the transfer paper P in the transport direction A, a registration roller 10 is provided on the upstream side of the transfer belt 6, and on the downstream side of the transfer belt 6, a fixing device 17 comprising a heating roller 17a and a pressure roller 17b. Are arranged. In the above structure, the original document illuminated by the halogen lamp (not shown) is projected onto the photoconductor drum 3 by the exposing means. At this time, the negative charge on the photosensitive drum 1 disappears due to the intensity of light, and an electrostatic latent image is formed. Next, toner is attached to the electrostatic latent image on the photosensitive drum 3 by the developing device to form a visible image (toner image). A negative bias voltage lower than the charging potential of the photosensitive drum 3 is applied to the developing sleeve of the developing device, and the toner positively positively charged by the stirring of the developing carrier is attached to the latent image on the photosensitive drum 3. Forming an image. Then P
The entire surface of the photosensitive drum 3 before transfer is exposed by the TL 15 to lower the surface potential and improve the transfer efficiency.

In the transfer process, the registration roller 10
The transfer sheet P that has been conveyed to and is on standby is sent out in the direction of arrow A from the registration roller 10 in time with the toner image on the photosensitive drum 3. At the same time, the transfer belt 6 is pushed up by the push-up lever 9 and comes into contact with the photoconductor drum 3 at the same time when the front end of the transfer paper P reaches the vicinity of the contact portion between the photoconductor drum 1 and the transfer belt 6. At this time, a nip portion having a width of 4 mm to 8 mm is formed at the contact portion. When the transfer paper P enters the nip width, a transfer bias voltage is applied to the transfer bias roller 11, and the transfer belt 6 is charged with an electric charge having a polarity opposite to that of the toner on the photoconductor drum 3 to perform transfer. . In this embodiment, as shown in FIG. 5, the toner of the (+) polarity is developed on the photosensitive drum 3 whose surface is charged to −800 V, and the PTL is used.
The surface potential on the photosensitive drum 3 is lowered by 15 and then the transfer bias roller 11 receives -1.5 Kv to -6.5 K.
The toner is transferred to the transfer paper P by applying a voltage of v. In the same figure, the size of the charge is represented by the size of the circle, and the state in which the charge is reduced by the PTL 15 is shown smaller than that before the static elimination.

The transfer conditions are as shown in FIG.
When the output current value output from the high voltage power source 12 is I ₁ and the feedback current value flowing from the ground plate 13 to the ground side via the transfer belt 6 is I ₂ , I ₁ −I ₂ = Iout (Iout is a constant The value of I ₁ is controlled so that In the case of this embodiment, Iout is −35 μA ± Iout at a conveying speed of 330 mm / sec and an effective bias roller length of 310 mm.
Good transfer was obtained when set to 5 μA. The value of the current Iout flowing on the photosensitive drum 1 side is not unique, and decreases when the transport speed is slow, and conversely increases when the transport speed is fast or when the PTL 15 is not used. .

When a transfer bias voltage is applied by the transfer bias roller 11, the transfer sheet P is charged, the toner image on the photosensitive drum 3 is transferred onto the transfer sheet P, and at the same time, the true charge on the transfer belt 6 is transferred. An electrostatic force is generated by the polarization charge of the paper P, and the transfer paper P is adsorbed on the transfer belt 6,
Separate from the photoconductor drum 3. Transfer paper P that is transferred and conveyed
Is gradually removed from the contact plate 13 via the transfer belt 6, and the charge amount is relaxed. Then, the transfer paper P having the weakened electrostatic attraction is separated from the transfer belt 6 at the position of the drive roller 5.

When this series of operations is completed, the push-up lever 9 is released and the transfer belt 6 separates from the photosensitive drum 1. This is to prevent contamination of the photoconductor drum 3 due to long-term contact between the transfer belt 6 and the photoconductor drum 1. At this time, on the transfer belt 6 being conveyed, there are toner scattered without being transferred onto the transfer paper P, residual toner directly attached to the transfer belt 6 and paper dust emitted from the transfer paper P. These are scraped off by the cleaning blade 16a that is in contact with the drive roller 5, and the toner receiver 1
It falls to 6. The paper powder and toner collected in the toner receiver 16 are transferred to the transfer belt unit 2 by the collecting coil 16b.
Is conveyed to a waste toner collecting bottle (not shown) of the copying machine body. On the other hand, after the transfer, the toner remaining on the photosensitive drum 3 is scraped off by the cleaning device. Finally, in order to erase the residual charges on the photosensitive drum 3 after cleaning, the entire surface is exposed by the charge eliminating lamp to prepare for the next copy.

Next, an embodiment based on claim 1 will be described. As shown in FIG. 1, in the non-sheet passing state, the transfer belt 6 is rotated by the drive roller 5 while the transfer belt 6 is separated from the photosensitive drum 3, and at the same time, the transfer bias voltage is applied to the transfer bias roller 11. Then, the toner attached to the surface of the transfer belt 6 repels the toner of the same polarity from the transfer belt 6 and easily separates from the transfer belt 6. For example, in the transfer process described above, since the transfer voltage has the (-) polarity and the toner to be transferred has the (+) polarity, the bias voltage having the same (-) polarity as the transfer is applied to the transfer bias roller 11 in the state of FIG. When (+) polarity is applied, the (+) polarity toner is more strongly adsorbed to the surface of the transfer belt 6, but as shown in FIG. -) The polar toner T ′ repels and is easily scraped off by the cleaning blade 16 a of the transfer belt 6.

The reason why the opposite (-) polarity toner T ', which is different from the normal toner, is generated and adheres to the transfer belt 6 is that the (+) toners rub against each other in the developing device and have the opposite polarity. This is considered to be because (−) toner having “−” is generated. In the time chart of this embodiment, as shown in FIG. 7, at the rising time I when the power is turned on and at the time K when the repeat of the copy operation is finished, cleaning by applying a transfer bias voltage or an ammeter 19 described later is performed.
Current measurement by. P ₁ , P ₂ , and Pn are transfer times of the transfer paper, and J is the interval between the transfer papers. Next, an embodiment based on claim 2 will be described. As shown in FIG. 8, the high voltage power supply 21 for cleaning is arranged in parallel with the high voltage power supply 12 (for transfer), and the changeover switch 23 can switch the voltage application to the transfer bias roller 11. In this configuration, when the transfer belt 6 is cleaned, the changeover switch 23 is controlled to apply a voltage having a (+) polarity opposite to the transfer voltage polarity to the transfer bias roller 11 by the cleaning high-voltage power supply 21, and the charging is normally performed. The (+) toner T that is being electrostatically repulsed electrostatically weakens the attraction force with the surface of the transfer belt 6 and is easily scraped off by the cleaning blade 16a.

The toner T adhering to the surface of the transfer belt 6 directly contacts the photosensitive drum 3 and the transfer belt 6 on the front, rear, left and right sides of the transfer paper when the photosensitive drum 3 and the transfer belt 6 come into close contact with each other. By doing so, it is considered that they are attached by electrical attachment or physical rubbing. In particular, it is considered that the negative polarity (−) toner T ′ (see FIG. 6) adheres to the surface of the transfer belt 6 due to physical rubbing. Regarding the time chart of this embodiment, as shown in FIG. 9, at the rising time I ′ when the power is turned on and the time K ′ at the end of the repeat of the copying operation, the polarity is opposite to that of the transfer by the cleaning high-voltage power supply 21. Perform cleaning. As in FIG. 7, P ₁ , P ₂ , and Pn are transfer times of the transfer paper, and J is the interval between the transfer papers. The operation procedure of this embodiment is shown in FIG.
After turning on the main motor (not shown),
The high voltage power supply 21 for cleaning is turned on and the transfer belt 6
Cleaning (steps S1, S2, S3),
Then, the DC solenoid 8 and the high voltage power supply 12 are turned on (steps S4 and S5). Then, after the copy operation is completed,
It is confirmed that the transfer paper P is separated from the transfer belt 6 (step S7), the high voltage power supply 12, the DC solenoid 8,
After turning off the main motors respectively (step S8,
(S9, S10), the high voltage power supply 21 for cleaning is turned on to clean the transfer belt 6 (step S1).
1, S12).

Next, an embodiment based on claim 3 will be described. As shown in FIG. 1, an ammeter 19 which is a current detecting means is connected to the ground plate 13. In this configuration, the current I ₂ returned via the ground plate 13 is measured by the ammeter 1
9, the electric resistance value R of the transfer belt 6 is calculated from R = E / I ₂ . For example, the distance from the transfer bias roller 11 to the ground plate 13 is set to 80 mm, and the high voltage power source 12 to E
= -2 kv is applied, I ₂ = -20 with ammeter 19
When μA is detected, the electric resistance value R of the transfer belt 6 becomes 1 × 10 ⁸ Ω (/ 80 mm) as a substantial resistance. From the electric resistance value of the transfer belt 6 thus obtained, the transfer voltage required during the normal copying operation is determined. Regarding the operation procedure of this embodiment, as shown in FIG. 11, after the main motor is turned on, the high voltage power supply 12 is turned on and the transfer current is detected by the ammeter 19 (steps S1, S2, S3), and thereafter,
The DC solenoid 8 is turned on (step S4). After the copying operation is completed, it is confirmed that the transfer paper P is separated from the transfer belt 6 (step S6), the DC solenoid 8 is turned off (step S7), and the transfer current is detected by the ammeter 19. Then, the high-voltage power supply 12 and the main motor are turned off (steps S8, S9, S10).

The embodiment of claim 1 is the same except that the operations of steps S3 and S8 of the operation procedure of FIG. 11 are not performed. Further, in another embodiment related to claim 3, an electrometer 20 is connected to the high voltage power source 12 as shown in FIG. In this configuration, a constant current I ₁ (for example, 20 μ
A) is supplied to connect the contact plate 13 to the ground, and the output power voltage E is measured by the electrometer 20. Based on the measurement result, the electric resistance value R of the transfer belt 6 is calculated as R = E / I ₁
It can also be calculated from

Further, as described in the above problem, the electric resistance value of the transfer belt 6 is not uniform over the entire circumference, and unevenness occurs locally. For example, in the case of an elastic transfer belt having an electric resistance of about 1 × 10 ⁸ Ω, depending on the temperature, humidity, tension, stress relaxation rate, and manufacturing variations, a maximum of about 1 × 10 ⁷ to 1 × 10 ¹⁰ Ω can be obtained. It may vary. Therefore, the average value is taken as the electric resistance value of the transfer belt 6, but, for example, in the case where the unevenness of the electric resistance value is large (the deviation is too large) and the transfer failure occurs beyond the control range of the high voltage power supply 12, the transfer failure occurs. Alternatively, a control panel (not shown) may be used to notify the abnormality. Not only the unevenness, but also the case where the electric resistance value of the transfer belt 6 is too high or too low as a whole can be notified as an abnormality.

Next, an embodiment based on claim 4 will be described with reference to FIG. As shown in FIG. 3A, transfer is performed while the transfer belt 6 is pressed to the photosensitive drum 3 by the biting amount d, and as shown in FIG. Transfer belt 6 to photosensitive drum 3
When the transfer bias roller 11 is separated further, the transfer bias roller 11 is separated from the transfer belt 6 although it is minute.

In the state shown in FIG. 3A, the transfer belt 6 of the transfer bias roller 11 needs to be conveyed in a substantially straight line for the distance L from the transfer paper to the time when the transfer paper leaves the transfer belt 6. This is because the amount of bite into is substantially 0 mm, and in the state shown in FIG. 7B, the transfer bias roller 11 is separated from the transfer belt 6. With such a configuration, the operations of claims 1, 2 and 3 described above cannot be performed. Therefore, as shown in FIG. 3C, one end is fixed to the apparatus main body side below the transfer bias roller 11, and the other end is fixed to the shaft portion (not shown) of the transfer bias roller 11. A pressing spring 2 which is a pressing means for urging the roller 11 in the direction of arrow B.
2 are provided. With this configuration, the transfer bias roller 11 is pushed by the pressing spring 22 and follows the position change of the transfer belt 6 due to the contacting / separating operation, and always maintains the state of being in contact with the transfer belt 6. However, the contact and separation of the transfer belt 6 with respect to the photosensitive drum 3 are performed with the driving roller 5 as the center of rotation. Further, if the biasing force by the pressing spring 22 is too strong, the distance L does not become a straight line in the state of FIG. To be done.

Further, in the embodiment of claim 5, the timing of performing the operations of claims 1, 2 and 3 is during the rising time when the power of the copying machine main body is turned on.
This is performed during heating of the fixing roller 17a. Further, the transfer sheet may be fed at the start of copying and may be moved to the transfer position. However, in this case, it is necessary to take a time for which the transfer belt 6 can be pre-rotated for one round or more. Further, in the embodiment of claim 6, the timing of performing the operations of claims 1, 2 and 3 is immediately after the transfer paper leaves the transfer belt 6 at the end of the repeat of the copy operation. Further, in the double-sided mode, etc., the timing for performing the above-described operation is used for the time when the transfer paper is finished being copied on one side, separated from the transfer belt 6, and stacked and re-fed. Further, in the embodiment of claim 7, the timing of performing the operations of claims 1, 2 and 3 is set immediately after the restoration when a jam (misfeed) occurs during copying. In this case, since there is no transfer paper on the transfer belt 6 due to misfeed, and the toner may be directly transferred to the transfer belt 6, the cleaning blade 1 in particular may be used.
It is necessary to sufficiently perform cleaning with 6a.

[0029]

As described above, according to the first aspect, according to the first aspect, the transfer belt is driven by the drive roller while the transfer belt is separated from the image carrier by the contacting / separating means. , The voltage of the same polarity as that at the time of transfer is applied to the transfer bias roller, and at the same time, the surface of the transfer belt is cleaned by the cleaning means, so that the toner having the same polarity as the transfer voltage existing on the transfer belt repels electrostatically. As a result, the suction force on the transfer belt surface is weakened, the cleaning efficiency of the cleaning means can be increased, and the backside of the transfer paper can be prevented from being contaminated.

According to a second aspect of the present invention, the transfer belt is driven by the drive roller in a state where the transfer belt is separated from the image carrier by the contacting / separating means, and is transferred to the transfer bias roller during transfer. At the same time that the voltage of the opposite polarity is applied, the surface of the transfer belt is cleaned by the cleaning means, so that the toner having the opposite polarity to the transfer voltage existing on the transfer belt is electrostatically repulsed, and the toner is transferred to the transfer belt surface. The suction force is weakened, the cleaning efficiency of the cleaning means can be increased, and the backside of the transfer paper can be prevented from being contaminated. According to claim 3,
The drive roller is provided with a contact plate that comes into contact with the surface or the inner surface of the transfer belt and a current detection unit that detects a current flowing from the contact plate, and the transfer belt is separated from the image carrier. Drive the transfer belt by
A predetermined voltage is applied to the transfer bias roller, the current is detected by the current detecting means, and the transfer voltage is determined from the detection result. Therefore, the transfer voltage according to the electric resistance value of the transfer belt should be applied. Therefore, stable and good transfer can be performed.

According to a fourth aspect of the present invention, the transfer bias roller is supported by pressing means for urging the transfer bias roller in a direction perpendicular to the transfer belt surface. The transfer belt can be held in contact with the transfer belt regardless of the position change of the transfer belt by the contacting / separating means. Therefore, even when the transfer belt is separated from the image carrier, the transfer belt according to any one of claims 1 to 3 can be used. You can take action. According to claim 5, since the operation timings of claims 1, 2 and 3 are during the start-up time when the power of the copying machine main body is turned on, the productivity of copying is not reduced. The respective effects of 2, 3, and 3 can be expected. In addition, claim 6
According to this, since the operation timings of claims 1, 2 and 3 are set to the end of the repeat during the copy operation, the same effect as that of claim 5 is achieved. Further, according to claim 7,
The operation timings of claims 1, 2, and 3 are the same as those of claim 5 since they are set immediately after the recovery in the case of a jam during the copy operation.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram showing a transfer / conveyance apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a transfer belt.

FIG. 3 is an explanatory diagram showing a configuration of a transfer belt unit.

FIG. 4 is a perspective view showing a removable transfer belt unit.

FIG. 5 is an explanatory diagram showing a charge state at the time of transfer of the transfer / conveyance device.

FIG. 6 is an explanatory diagram showing a charge state of the operation of claim 1;

FIG. 7 is a time chart showing the operation of claim 1.

FIG. 8 is an explanatory diagram showing a charge state of the operation of claim 2;

FIG. 9 is a time chart showing the operation of claim 2.

FIG. 10 is a flowchart showing an operation procedure of claim 2;

FIG. 11 is a flowchart showing an operation procedure of claim 3;

FIG. 12 is an overall schematic configuration diagram showing a transfer / transport device to which an electrometer is connected.

FIG. 13 is an explanatory diagram showing a positional relationship between a transfer belt and a transfer bias roller.

[Explanation of symbols]

 3 image carrier 4 driven roller 5 drive roller 6 transfer belt 8, 9 contact / separation means 11 transfer bias rollers 16, 16a, 16b cleaning means 19 current detection means 22 pressing means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Hisashi Ito 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. No./Ricoh Company (72) Inventor Yuko Harasawa 1-3-6 Nakamagome, Ota-ku, Tokyo-Ricoh Company (72) Koichi Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo- Stock company Ricoh

Claims (7)

[Claims] 1. A transfer belt which contacts an image carrier and is supported by a driving roller and a driven roller, a transfer bias roller which applies a predetermined transfer voltage to the transfer belt, and a cleaning which cleans the surface of the transfer belt. And a contacting / separating device for contacting / separating the transfer belt with respect to the image carrier, wherein the transfer belt is separated from the image carrier by the contacting / separating unit, A transfer / conveyance device, characterized in that the transfer belt is driven by the drive roller, a voltage having the same polarity as that at the time of transfer is applied to the transfer bias roller, and at the same time, the surface of the transfer belt is cleaned by the cleaning means. 2. In the transfer / conveying device, the transfer belt is driven by the drive roller in a state where the transfer belt is separated from the image carrier by the contacting / separating means, and is transferred to the transfer bias roller. A transfer / conveyance apparatus, characterized in that the cleaning means cleans the surface of the transfer belt at the same time as applying a voltage of the opposite polarity. 3. A state in which a contact plate that comes into contact with the surface or the inner surface of the transfer belt and a current detection unit that detects a current flowing from the contact plate are provided, and the transfer belt is separated from the image carrier. Then, the transfer belt is driven by the drive roller, a predetermined voltage is applied to the transfer bias roller, the current is detected by the current detecting means, and the transfer voltage is determined from the detection result. The transfer / conveyance apparatus according to claim 1 or 2. 4. The transfer bias roller is supported by pressing means for urging the transfer bias roller in a direction perpendicular to the transfer belt surface. Transfer / transport device. 5. The transfer / conveyance apparatus according to claim 1, 2 or 3 wherein the operation timing is during the rising time when the power of the copying machine main body is turned on. 6. The transfer / conveyance apparatus according to claim 1, 2 or 3, wherein the operation timing is at the end of the repeat during the copy operation. 7. The transfer / conveyance apparatus according to claim 1, 2 or 3, wherein the operation timing is immediately after the recovery when a jam occurs during the copy operation.