JP3502676B2 - Transfer transfer device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / transport apparatus for transferring a toner image by holding a transfer sheet between a transfer belt and an image carrier. 2. Description of the Related Art A contact electrode is brought into contact with a transfer belt for reasons such as less generation of ozone than a corona transfer method, a reduced power supply capacity, and good transfer paper separation / conveyance performance. The present applicant has proposed a contact-type transfer belt system in which the voltage is applied. For example, JP-A-5-11
In the transfer belt device described in Japanese Patent No. 3725, a first contact electrode for applying a transfer voltage to the transfer belt and an upstream and near a transfer position in a moving direction of the transfer belt are provided. A second contact electrode for applying a charge for controlling a transfer voltage and a second contact electrode are arranged on the left and right sides of the photoconductor, and a transfer bias is applied to the transfer belt from the left and right sides of the photoconductor. In this way, when the transfer bias is applied to the photosensitive member from both the left and right sides, good transfer can be performed even if the transfer belt has uneven resistance, but the separation property of the paper at high humidity is improved. Bad, there are many transcription dust. Therefore, the applicant of the present application has proposed a one-side application method in which a transfer electrode is arranged only on the rear side of a photoreceptor and a transfer bias is applied from the rear side, for example, in Japanese Patent Application Laid-Open No. Hei. No. 5839. In this one-side application method, the transfer belt is passed over a conductive roller, and a pre-transfer static elimination lamp is arranged upstream of a nip portion that is a contact portion between the photoconductor and the transfer belt, and the static elimination lamp is transferred before the transfer. By irradiating a lamp, the adhesive force between the photoconductor and the toner is reduced to increase the transfer efficiency. However, when the resistance of the transfer belt is low in the one-sided application method, if the potential of the roller disposed upstream of the nip becomes high due to the transfer bias applied from the transfer electrode, the charge of the pre-transfer static elimination lamp causes the transfer to the photosensitive member. The toner having a reduced adhesive force is attracted to the transfer paper side before the nip portion, causing transfer dust. SUMMARY OF THE INVENTION It is an object of the present invention to provide a transfer / conveyance apparatus using a one-side application method capable of obtaining a good transfer image by reducing transfer dust. Therefore, in the invention according to the first aspect, a transfer formed by a medium resistor and capable of contacting the outer peripheral surface of the image carrier and being rotationally driven by a driving means. The belt, disposed upstream of the image carrier in the rotation direction of the image carrier, a charge removing unit that removes electricity on the image carrier that is not in contact with the outer peripheral surface, and charges the transfer belt via a contact electrode that directly contacts the transfer belt. A charge supply unit for supplying, and a control unit for controlling an output of the charge elimination unit based on a resistance value of the transfer belt, wherein the control unit sets the resistance value of the transfer belt in the apparatus.
If it is lower than the stored set resistance value, the static elimination means is turned off. According to the first aspect of the present invention, a transfer belt formed of a medium resistor and capable of contacting the outer peripheral surface of the image carrier is provided on the upstream side in the image carrier rotational direction in non-contact with the outer peripheral surface of the image carrier. Since the output of the arranged static eliminator is controlled by the controller based on the resistance value of the transfer belt, the static elimination state on the image carrier changes according to the resistance value of the transfer belt. Also, the transfer belt resistance
When the resistance value is lower than the set resistance value stored in the printer, the control means turns off the charge removing means. Therefore, if the potential of the transfer belt is high, the outer peripheral surface of the photoreceptor is not removed. Embodiments of the present invention will be described with reference to the drawings. (First Embodiment) In a transfer / conveying apparatus indicated by reference numeral 1 in FIG. 1, a belt unit 2 is detachably supported on a main body 1A. The belt unit 2 is a medium-resistance transfer belt wound around a pair of rollers 4 and 5 constituting driving means for transferring a toner image from a drum-shaped photosensitive member 3 as an image carrier shown in FIG. 6, a DC solenoid 8 for bringing the belt 6 into and out of contact with the photoreceptor 3, a contact / separation lever 9, a bias roller 11 as a contact electrode for applying a transfer bias to the transfer belt 6, and a contact for removing charges from the transfer belt 6 Board 1
3. The output of a pre-transfer static elimination lamp (PTL) 15 and a pre-transfer static elimination lamp (PTL) 15 which are arranged on the upstream side in the rotation direction of the photoconductor 2 and serve as static elimination means for neutralizing the outer peripheral surface 3 a of the photoconductor 3. A static elimination control plate 19 as control means. A cleaning blade 16 for scraping off residual toner and paper debris of the transfer paper S adhered to the surface of the transfer belt 6
A cleaning device 16 and bias roller 11
A high-voltage power supply 12 as a charge supply means for applying a bias voltage to the main body 1A is provided on the main body 1A shown in FIG. As shown in FIGS. 1 and 2, the roller 5 has a gear 5b connected to a drive motor (not shown) and is driven to rotate. The transfer belt 6 can move in the transport direction of the transfer paper S (the direction of the arrow A in FIG. 3) at a position facing the photoconductor 3 following the rotation of the roller 5. As shown in FIG. 5, the transfer belt 6 has a two-layer structure. When the electric resistance measured by JIS K6911 is 100 V DC, the surface layer 6 b has a surface resistivity of 1 × 10 ⁹ when the DC resistance is 100 V.
Ω to 1 × 10 ¹² Ω, the surface resistivity of the inner layer 6a is 1 × 10
⁷ Ω to 1 × 10 ⁹ Ω and its volume resistivity is 5 × 1
0 ⁸ Ω · cm~5 those set in the × ¹⁰ 10 Ω · cm. The rollers 4 and 5 are rotatably supported by a support 7 as shown in FIGS. The support 7 can swing about the support shaft 5 a of the roller 5, which is located downstream of the transfer position with respect to the photoconductor 3, in the transfer paper transport direction indicated by the arrow A among the rollers 4 and 5. . The support 7 is operated by a DC solenoid 8 driven on the transfer position side of the transfer belt 6 by a signal from a control plate 8A. That is, the DC solenoid 8
, A contact / separation lever 9 is connected, and the contact / separation lever 9 moves the support 7 to move the transfer belt 6 toward and away from the photoconductor 3. The control plate 8A is configured such that the leading end of the transfer paper S conveyed in a state where it is aligned with the leading end position of the toner image formed on the photoreceptor 3 by the pair of registration rollers 10 serving as the sheet conveying means is used for the photoreceptor. When approaching 3, a drive signal is issued to drive the DC solenoid 8. Accordingly, when the DC solenoid 8 is driven, the support 7 comes close to the photoconductor 3 and the transfer belt 6 contacts the photoconductor 3 as shown in FIG. A nip portion B is formed in which the transfer paper S can be transported while being in contact with the photoconductor 3. [0010] Of the rollers 4 and 5 described above, the roller 4 located in the vicinity of the photoreceptor 3 is configured as a driven roller to the roller 5 on the driving side.
As shown in FIG. 2, both ends 4a, 4a in the axial direction are formed in a tapered shape to prevent the transfer belt 6 from being shifted. The roller 4 is formed of a conductive roller such as a metal, but only supports the belt having the above-described electrical resistance, and is not directly in electrical contact with other conductive members. Drive side roller 5
For driving, a material such as EPDM rubber, chloroprene rubber, or silicone rubber is selected from the function of enhancing the gripping force on the transfer belt 6 during driving. The bias roller 11 is provided on the downstream side of the roller 4 in the moving direction of the transfer belt 6 (left side in FIGS. 3 and 4) so as to contact the inside of the transfer belt 6. The bias roller 11 constitutes a contact electrode for applying a charge having a polarity opposite to the charge polarity of the toner on the photoconductor 3 to the transfer belt 6.
It is connected to the. The contact plate 13 is disposed on the inner surface of the belt near the roller 4 on the lower side of the transfer belt 6 which is not the transfer paper transfer surface, and suppresses charge injection to the transfer paper S described later. The contact plate 13 is for detecting a current flowing on the transfer belt 6 as a feedback current, and the current supplied from the bias roller 11 is controlled by detecting the current. For this reason, a transfer control plate 14 for setting a supply current to the bias roller 11 according to the detection current is connected to the contact plate 13, and the transfer control plate 14 is connected to the high-voltage power supply 12. I have. The pre-transfer static elimination lamp (PTL) 15 is connected to an input device 18 such as an operation panel via a power source 21 and a static elimination control board 19. The neutralization control plate 19 normally turns on the pre-transfer neutralization lamp (PTL) 15 before the transfer, irradiates the photoconductor 3 with light, and electrostatically attaches the toner image to the outer peripheral surface 3 a of the photoconductor 3. The power supply 21 is controlled so as to weaken the suction force of the power supply. Further, the resistance value (VI value) of the transfer belt 6 is stored in the charge removal control plate 19, and the belt resistance value (VI value) after the belt tension input from the input device 18 is set. When the resistance value reaches the preset value, the power supply 20 is controlled to turn off the pre-transfer neutralization lamp (PTL) 15 so as not to irradiate light. In such a transfer / transport apparatus 1, as shown in FIG. 4, the support 7 brings the transfer belt 6 closer to the photosensitive member 3 as the transfer paper S is fed out from the registration roller 10. The width is set to 4 to 8 mm corresponding to the length along the transport direction of the transfer paper S between the photoconductor 3 and the photoconductor 3.
A nip B is formed. On the other hand, the surface of the photoconductor 3 is, for example,-
As shown in FIG. 6, the toner is moved to the nip portion B with the positively charged toner electrostatically adsorbed on the surface thereof. The photoreceptor 3 is arranged near the photoreceptor 3 before reaching the nip portion B, and the surface potential is reduced by a pre-transfer charge removing lamp 15 that weakens the charge on the surface of the photoreceptor 3. In FIG. 6, the height of the charged charges is represented by the size of a circle, and the state in which the charged charges are reduced by the pre-transfer charge removing lamp 15 is shown smaller than the circle before the charge removal. In the nip portion B shown in FIG.
The upper toner is transferred onto the transfer paper S by the transfer bias from the bias roller 11 located on the transfer belt 6 side. This transfer bias is from -1.5 kv to -6.5 kv
Is applied from the high-voltage power supply 12 in the range described above. As a result of the constant current control described below, the transfer bias is variably set. That is, in FIGS. 3 and 4, the current value output from the high-voltage power supply 12 is I _1, and the value when the feedback current value flowing from the contact plate 13 to the ground side via the transfer belt 6 is I ₂ . If, I ₁ over between two I ₂ = I _OUT (However, I _OUT: constant) controlling the value of _{I 1} so that the relation is obtained for ... (1). this is,
Temperature, regardless of variations occurring in the production quality of changes in the environmental conditions and the transfer belt 6 such as humidity, is done to eliminate the change in the transfer efficiency by stabilizing the surface potential V _P on the transfer sheet S . [0017] That is, by Mitateru the current flowing to the photosensitive member 3 side through the transfer belt 6 and the transfer sheet S as I _{OU T,} the transfer belt due to low resistance or high resistance of the surface resistance V _P on the transfer sheet S 6 is prevented from affecting the separation performance and transfer performance of the transfer paper S. In this embodiment, I
_{As for OUT} , good transfer is obtained when I _OUT = 35 μA ± 5 μA at a conveying speed of 330 mm / sec and an effective bias roller length of 310 mm. When the image is transferred from the photosensitive member 3, the transfer paper S is also charged at the same time. Therefore, the transfer paper S is electrostatically attracted onto the transfer belt 6 and the transfer paper S is separated from the photoconductor 3 by the relationship between the true charge of the transfer belt 6 and the polarization charge generated on the transfer paper S side. I can do it. Then, the separation of the transfer paper S from the photoconductor 3 is promoted by the peeling operation based on the rigidity of the transfer paper S using the curvature separation of the photoconductor 3. However, in such electrostatic attraction, when the humidity is high due to a change in environmental conditions, the current easily flows through the photoconductor 3, so that the transfer paper S cannot be separated properly. Therefore, the surface layer 6b of the transfer belt 6 shown in FIG.
, The transfer of the true charges to the transfer sheet S in the nip portion B is delayed, and the bias roller 11 is further moved downstream of the nip portion B in the transfer sheet transport direction. Side. Thus, the transfer of the true charges from the transfer belt 6 to the transfer sheet S is delayed, so that the electrostatic attraction relationship between the transfer sheet S and the photoconductor 3 is avoided. To delay the transfer of the true charge used in this case means that no charge is generated on the transfer sheet S upstream from the transfer sheet S to the nip portion B on the photosensitive member 3 side. . This prevents the transfer paper S from being wound around the photoconductor 3 and also prevents the transfer paper S from separating from the photoconductor 3 from being poorly separated. Further, on the transfer belt 6 side, it is better to select a material having a small resistance change due to an environmental change. As the conductive material for controlling the resistance, carbon,
When a suitable amount of zinc oxide or the like is added and a rubber belt is used as the elastic belt, a material having a low hygroscopic property and a stable resistance value such as chloroprene rubber, EPDM rubber, silicone rubber, and epichlorohydrin rubber may be selected. desired. The current I _OUT flowing to the photoconductor 3 side
Is not unique and can be reduced when the transport speed is low, and conversely, when the pre-transfer static elimination lamp 15 is not used, it is increased compared to when the pre-transfer static elimination lamp 15 is not used. become. On the other hand, the transfer paper S passing through the nip portion B is
The transfer belt 6 is electrostatically attracted and conveyed in accordance with the movement of the transfer belt 6, and the roller 5 on the driving side separates the curvature. For this reason, the diameter of the roller 5 is set to 16 mm or less. Further, when such a roller 5 is used, a high quality 45K
Paper (stiffness transverse 21 [cm ^3/100]) experimental results that it is possible to separate is obtained. The transfer paper S separated from the transfer belt 6 by the driving roller 5 is guided by a guide plate and conveyed between a heating roller 17a and a pad roller 17b constituting the fixing unit 17. In the fixing unit 17, the toner on the transfer paper S is heated and melted and pressed against the transfer paper S to fix the toner on the transfer paper S. The transfer belt 6 on which the image transfer to the transfer paper S and the separation have been completed is placed on the DC solenoid 8.
The release lever 9 is released in response to the release of the excitation, and the support 7 is separated from the photoconductor 3. Then, the surface is cleaned by the cleaning device 16. The cleaning device 16 includes a cleaning blade 16A. By rubbing the transfer belt 6, the toner transferred from the outer peripheral surface 3a of the photoreceptor 3 and scattered around the transfer belt 6 without being transferred. The attached toner and paper powder of the transfer paper S are scraped off. The transfer belt 6 rubbed by the cleaning blade 16A has a low friction coefficient to prevent a phenomenon such as an increase in driving force due to an increase in rubbing resistance or a turning-up of the cleaning blade 16A. A material such as polyvinyldene fluoride, ethylene tetrafluoride, or the like is coated. The toner or paper dust scraped off from the surface of the transfer belt 6 is stored from the main body 1A into a waste toner collecting container (not shown) by the collecting screw 16B. FIG. 7 is a graph showing the measured resistance change after the transfer belt 6 is manufactured. The vertical axis indicates the VI value, which is the current value at a certain applied voltage, and the horizontal axis indicates the number of days left unattended. The minus number of days shown in this table is a measurement in the course of manufacturing, and the leaving of the transfer belt 6 has started from the zero point. The leaving periods are 10, 30 and 53 days, respectively. After leaving
When the transfer belt 6 is stretched around the rollers 4 and 5, the VI value increases. The temporal variation in the state where the transfer belt 6 is stretched is such that the VI value is initially high and the resistance value of the transfer belt 6 is low, but the VI value decreases from a certain point in time, and the transfer belt 6
Resistance increases. The VI value in this table is 10
When the value exceeds 0, it was observed that the potential of the roller 4 was increased, pre-transfer occurred, and transfer dust occurred. In the first embodiment, the set resistance value (VI value) stored in the charge removal control plate 19 is set to 100 or less based on this observation result. Therefore, the resistance value of the transfer belt 6 after being stretched during use is measured, and the measurement result is input to the charge removal control plate 19 by the input device 18. If the input value exceeds 100, the charge removal control plate 19 As a result, the power supply 21 is controlled to turn off the pre-transfer neutralizing lamp 15, and the neutralizing action on the photoconductor 3 is eliminated. Accordingly, the electrostatic attraction of the toner to the photoconductor 3 does not decrease (the size of the circle in FIG. 6 does not change), so that even if the potential of the roller 4 increases, the potential on the photoconductor 3 due to the potential of the roller 4 increases. Of the toner to the transfer paper S side is suppressed. Therefore, with such a configuration, pre-transfer is reduced, and a good image with less image dust can be obtained. In the graph shown in FIG. 7, the test was performed twice under each leaving condition, but the same change was observed in other belts. Therefore, the resistance and the leaving period of the transfer belt 6 immediately after the production became clear. 7 shows the resistance value after the belt is stretched.
Therefore, the resistance value of the transfer belt 6 can be directly input without measuring and inputting the resistance value of the transfer belt 6 during stretching. Also,
Data corresponding to FIG. 7, that is, data of the belt resistance value at the time of stretching corresponding to the transfer belt 6 and the belt resistance value based on the number of days left, is stored in advance in the charge removal control plate 19, The resistance value of the transfer belt 6 and the data of the leaving period may be inputted, and the resistance value of the transfer belt 6 at the time of stretching may be determined by the charge removal control plate 19, and the on / off control of the charge removal lamp 15 before transfer may be performed. Next, some examples will be described. Members that operate in the same manner as in the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and description thereof is omitted . In this embodiment, as shown in FIG. 8, the pre-transfer static elimination lamp 15 is connected to the high-voltage power supply 12 via a static elimination control plate 19A that controls the on-off of the pre-transfer static elimination lamp 15 by the output of the high-voltage power supply 12. . The static elimination control board 19A constantly monitors the output of the high-voltage power supply 12, stores data of the VI value due to the voltage change, and the VI value exceeds 100.
And turns off the pre-transfer charge removing lamp 15 and have Ru, V-I value is controlled to be the pre-transfer charge removing lamp 15 turned on at that below 100. From the output change of the high-voltage power supply 12, V
Since the on / off control of the pre-transfer neutralizing lamp 15 is performed by checking the change of the -I value, when the potential of the roller 4 is strong, the first
As in the embodiment, since the charge on the photosensitive member 3 is not removed by the pre-transfer charge removing lamp 15, the attraction force of the toner attached on the photosensitive member 3 does not decrease. Therefore, the movement of the toner on the photoconductor 3 due to the high potential of the roller 4 can be reduced, so that the pre-transfer can be prevented, and a stable transfer image with less transfer dust can be obtained. In this example, as shown in FIG. 9, a measuring means 20 is interposed between the static elimination control plate 19B and the pre-transfer static elimination lamp 15. The photoreceptor 3 is degraded by light, ozone, and the like over time. In particular, light fatigue is large, and as shown in FIG. 10, the residual potential of the photoreceptor 3 tends to increase as the number of copies increases. In contrast, when the pre-transfer static elimination lamp 15 is turned off and copying is performed,
It was found that the rise in the residual potential of the photoconductor 3 was considerably suppressed. The measuring means 20 measures the off time of the pre-transfer static elimination lamp 15, and inputs the number of copies corresponding to the measurement result to the static elimination control board 19B. Static elimination control board 19B
The reference number of copies shown in FIG. 10C corresponding to the normal life (residual potential) of the photoconductor 3 when the pre-transfer static elimination lamp 15 is not controlled, and the photoconductor 3 when the pre-transfer static elimination lamp 15 is controlled. The ideal number of copies indicated by D in FIG. 10 corresponding to the life (residual potential) is set, and the number of copies corresponding to the off time input from the measuring means 20 is added to the reference number of copies. When the ideal number of copies is reached, an unillustrated life indicator of the photoconductor 3 is activated. In this way, the off-time of the pre-transfer neutralizing lamp 15 is measured, and the number of copies corresponding to the measured time is added to the reference number of copies. Therefore, when the off-time of the pre-transfer static elimination lamp 15 is long, the rise of the residual potential of the photoconductor 3 becomes slower than in the case where the on-time of the pre-transfer static elimination lamp 15 is not controlled, and the life of the photoconductor 3 is reduced. Will lead to an extension. This example is based on the on / off state of the pre-transfer static elimination lamp 15.
The off control is performed at a time other than the image forming operation (before image formation). The light of the pre-transfer neutralization lamp 15 is
As shown by the hatched portion in FIG. 11, the sheet spreads in the circumferential direction of the photoconductor 1, and therefore, during the image forming operation, for example, as shown in FIG. 12, the space between the first transfer sheet P and the next transfer sheet P In L, when the on / off control of the pre-transfer static elimination lamp 15 is performed, a portion where the light of the lamp 15 shines and a portion where the light does not shine are formed in one image, and the charged state of the toner forming the image becomes uneven. And the image condition becomes strange. This phenomenon is that when the belt resistance value is low, the transferability is changed by the pre-transfer static elimination lamp 15, and a dark portion and a light portion occur in the transferred image. If the pre-transfer static elimination lamp 15 is turned off when the belt resistance is high, the transfer dust will change. Then, when the control of the pre-transfer static eliminating lamp 15 was performed before the image formation, a good image could be obtained. As described above, before the toner image is formed on the photoconductor 3, the pre-transfer static elimination lamp 15 is turned on / off in accordance with the state of the transfer belt 6, so that the toner image formed on the photoconductor 3 is formed. Since the irradiation light of the pre-transfer static elimination lamp 15 does not irradiate the toner image, it is possible to prevent the transfer dust while stabilizing the charged state of the toner image. According to the present invention, since the charge removing means for removing charge from the photoreceptor is controlled by the resistance value of the transfer belt to change the charge removal state on the image carrier, the resistance of the usable transfer belt can be reduced. The value range can be widened, the yield can be improved, the cost of the transfer belt can be reduced, and the transfer dust can be reduced. According to the present invention, when the resistance value of the transfer belt is low, the control unit turns off the charge removing unit and does not remove the charge on the outer peripheral surface of the photoconductor, so that the toner image formed on the photoconductor can be stabilized, and the transfer dust can be improved. Can be prevented .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a schematic configuration of a transfer / conveyance device embodying the present invention. FIG. 2 is a plan view illustrating a schematic configuration of a transfer belt unit. FIG. 3 is a side view showing a schematic configuration of the first embodiment of the present invention. FIG. 4 is a side view showing an operation at the time of transfer in the first embodiment. FIG. 5 is a partially enlarged cross-sectional view of a transfer belt used in the transfer conveyance device of the present invention. FIG. 6 is an enlarged view illustrating a transfer operation of toner particles. FIG. 7 is a diagram illustrating a change in a resistance value of a transfer belt. FIG. 8 is a block diagram showing a main configuration of a second embodiment of the present invention. FIG. 9 is a block diagram showing a main configuration of a third embodiment of the present invention. FIG. 10 is a graph showing durability characteristics of an image carrier according to a fourth embodiment of the present invention. FIG. 11 is a side view showing a static elimination area by the static elimination means. FIG. 12 is a side view showing an example of a non-operating region of the static elimination means. DESCRIPTION OF SYMBOLS 1 Transfer / conveyance device 3 Image carrier 3a Outer peripheral surfaces 4, 5 Driving means 6 Transfer belt 11 Contact electrode 12 Charge supply means 15 Static elimination means 19 Control means 19A Control means 19B Control means 20 Measurement means

Continued on the front page (72) Inventor Yuko Harasawa 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Koichi Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo, Co. Inside Ricoh Company (72) Inventor Satoshi Takano 1-3-6 Nakamagome, Ota-ku, Tokyo, Inc. Inside Ricoh Company (72) Akio Kutta 1-3-6, Nakamagome, Ota-ku, Tokyo, Inc. (56) References JP-A-3-231783 (JP, A) JP-A-2-8874 (JP, A) JP-A-4-204780 (JP, A) JP-A-4-208970 (JP) , A) JP-A-60-57860 (JP, A) JP-A-61-85872 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/14-13/16 G03G 15/14-15/16

Claims (1)

(57) Claims: 1. A transfer belt formed of a medium resistor and capable of contacting the outer peripheral surface of an image carrier, and a transfer belt disposed upstream of the transfer belt in the image carrier rotation direction. A static eliminator for eliminating static on the image carrier that is not in contact with the outer peripheral surface; a driving unit for rotating the transfer belt; a contact electrode directly in contact with the transfer belt; and the transfer belt via the contact electrode. And a control means for controlling the output of the charge elimination means in accordance with the resistance value of the transfer belt . The control means stores the resistance value of the transfer belt in the apparatus.
Transfer transfer device that turns off the charge removing means when the resistance is lower than the set resistance value .