JP4083953B2 - Image forming apparatus and contact transfer apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and a contact transfer apparatus.
[0002]
[Prior art]
In image forming apparatuses such as copying machines, printers, and facsimiles, a contact transfer member such as a transfer belt and a transfer roller is used as a transfer apparatus that transfers a toner image on an image carrier such as a drum-shaped photosensitive member to a sheet such as transfer paper. Some use a contact transfer device. The contact transfer device applies a transfer bias to a contact transfer member from a transfer bias power source to transfer a toner image on the image carrier to a sheet between the contact transfer member and the image carrier, and removes the sheet from the contact transfer member. The transfer current flowing to the image carrier through the differential constant current method or the constant current method is controlled.
[0003]
In the differential constant current method, a target current value is determined to detect a feedback current from the contact transfer member, and an output current from the transfer bias power source to the contact transfer member is determined by adding the target current value to the feedback current (transfer). The output current of the transfer bias power supply is controlled so that the current value obtained by subtracting the feedback current from the output current of the bias power supply becomes the target current value). This differential constant current method can cope with uneven resistance of the contact transfer member. In the constant current method, an output current from the transfer bias power source to the contact transfer member is set as a target current value.
[0004]
In Japanese Patent Laid-Open No. 9-15994, an electrostatic latent image formed on an image carrier by an electrophotographic process is developed into a toner image by a developing means, and an electrostatic latent image under the toner image is removed by a pre-transfer charge eliminating means. The image charge is discharged, and the toner image is transferred onto the transfer paper sandwiched between the image carrier and the transfer belt by the transfer means, and the transfer paper is separated from the transfer belt and fixed by the fixing means. An image forming apparatus for performing image formation, comprising: a static elimination control unit that controls an output of the pre-transfer neutralization unit based on at least one of a resistance value and a toner density of the transfer belt. An apparatus is described.
[0005]
Japanese Patent Application Laid-Open No. 10-3235 discloses an image carrier that carries a toner image, an endless transfer belt as contact transfer means for transferring the toner image on the image carrier to a sheet that carries and carries a sheet, A first electrode that contacts a surface opposite to the transfer belt and applies a transfer bias to the transfer belt, a second electrode that contacts the transfer belt, and a transfer bias is supplied to the first electrode I and the current value output from the power source₁, A current value flowing from the power source to the second electrode via the transfer belt is expressed as I₂The transfer current output value Iout = I₁-I₂A transfer control means for variably controlling the current value I1, a target current value control means for controlling the target current value according to a set condition, and a toner image on the sheet. A post-transfer neutralization unit that neutralizes residual charges on the image carrier after the image transfer, a post-transfer neutralization control unit that controls the post-transfer neutralization unit according to set conditions, and a temperature of the image carrier. In the image forming apparatus, comprising: a belt resistance detection unit that detects a resistance value of the transfer belt; and a sheet size detection unit that detects the size of the sheet. The image forming apparatus is characterized in that the control means varies the output of the post-transfer charge eliminating means to the image carrier based on the temperature of the image carrier detected by the image carrier temperature detecting means. ing.
[0006]
Japanese Patent Laid-Open No. 10-123845 discloses that a transfer belt that is wound around a drive roller and a driven roller and is movable by driving of the drive roller and a photosensitive member carrying a toner image are transferred in a predetermined nip region. The photosensitive member and the transfer belt are driven in a state where paper is sandwiched, and a transfer bias from a power source is applied to the transfer belt by a transfer unit disposed in contact with the transfer belt. In the transfer device for transferring the upper toner image to the transfer paper, the current flowing into the photoconductor among the currents output from the power source is output from the power source so as to become a preset target value. A transfer current control means for controlling current; and a contact arrangement between the transfer means and the driven roller in contact with the transfer belt at a position near the upstream of the transfer belt movement in the nip area. It is, transfer device and having a potential drop means for lowering the potential of the transfer belt is described.
[0007]
In JP-A-5-297735, charging, image exposure, and development are repeated to form a multicolor toner image by superimposing a toner image on an image carrier, and the multicolor toner image is transferred to a transfer material. Therefore, in an image forming apparatus including a transfer belt device that is stretched and rotated between holding rollers, a power source for applying a transfer electric field to the transfer material of the transfer belt device, the transfer material or the transfer material, A detecting means for detecting a current value that fluctuates depending on a resistance value of a conveying member of the transfer belt device, and when the detecting means is operated, an output current or an output voltage of the power source is fixed to a constant value, and the transfer material An image forming apparatus is described in which a current value or a voltage value of the power source is changed to a value selected based on a result detected by the detecting means before entering the transfer area.
[0008]
In JP-A-6-35337, charging, image exposure, and development processes are repeated to form a multicolor toner image by superimposing a toner image on an image carrier, and the multicolor toner image is transferred to a transfer material. Therefore, in an image forming apparatus including a transfer belt device that is stretched and rotated between holding rollers, a transfer power source for applying a transfer electric field to the transfer material of the transfer belt device, and the transfer material or the transfer material The image forming apparatus includes a detecting unit that detects a paper charging current value that varies depending on a resistance value of a conveying member of the transfer belt device, and the transfer power source is turned on after the detection of the paper charging current by the detecting unit is completed. An image forming apparatus is described.
[0009]
Japanese Patent Application Laid-Open No. 7-248687 discloses a transfer belt that contacts an image carrier, a voltage applying member that applies a voltage to the transfer belt, a power source for applying a voltage, and a contact with the transfer belt. A belt transfer apparatus comprising a grounding member for feeding back current to the power source, wherein the belt comprises drive means for moving the grounding member back and forth in the rotational direction on the transfer belt. A transfer device is described.
[0010]
Japanese Patent Laid-Open No. 8-339127 discloses an endless transfer belt stretched around a plurality of rollers so as to form a transfer portion in contact with or close to an image carrier on which an image to be transferred is formed, A charge supply means for supplying a transfer charge to the surface of the transfer belt opposite to the image carrier side, supporting the transfer material by the transfer belt, transporting it to the support section, and supplying the charge by the charge supply means In a transfer device that transfers a transfer image on the image carrier onto a transfer material by transfer charge, on a part of the transfer material passing through the transfer portion on the downstream side of the transfer portion in the transfer material transport direction. A facing corona charger, an AC power source that applies an AC voltage to the corona charger, and a transfer material current detection that detects a DC current flowing between the AC power source and the transfer material via the corona charger Means, at least one of the transfer belt and the plurality of support rollers Supporting roller current detecting means for detecting a direct current flowing between them, and control for changing the setting of the output current amount of the charge supplying means based on detection results of the transfer material current detecting means and the supporting roller current detecting means And a transfer device, characterized in that a transfer device is provided.
[0011]
Japanese Patent Laid-Open No. 8-339127 discloses a transfer belt for bringing a transfer material into contact with the surface of an image carrier on which an image to be transferred is formed, a belt support for supporting the transfer belt, and a transfer charge on the transfer belt. Charge supply means for controlling the charge supply means, and controlling the charge supply means so that a difference current between an output current amount from the charge supply means and a current amount flowing from the transfer belt to the belt support becomes a predetermined current amount. In a transfer apparatus comprising a constant current control means, a potential detection means for detecting a potential of a charge supply region to which charges are supplied by the charge supply means on the transfer belt, and a transfer material in a state where there is no transfer material. A result of detecting the potential of the charge supply region when the differential current becomes the predetermined current amount by the potential detecting means and the differential current is the predetermined current amount in a state where there is a transfer material at the transfer position. Comparing means for comparing the electric potential of the charge supply region at the time of detection with the result detected by the electric potential detecting means, and correcting means for correcting the predetermined current amount based on the comparison result by the comparing means are provided. Is described.
[0012]
In Japanese Patent Laid-Open No. 10-198195, a transfer material is introduced along a transfer guide into a transfer portion that is an opposite portion between an image carrier and a transfer unit, and a bias is applied to the transfer unit to apply to the surface of the image carrier. In an image forming apparatus for transferring a formed image to a transfer material, a varistor having a predetermined resistance value when an applied voltage exceeds a threshold value v1 is disposed between a transfer guide and a ground, and the varistor is set according to the resistance value of a transfer unit. An image forming apparatus characterized in that the threshold value v1 is changed is described.
[0013]
In Japanese Patent Laid-Open No. 10-207262, “a transferable image on the image carrier side is transferred to the recording medium side by passing the recording medium between the image carrier and a transfer member which is in contact with the image carrier and to which a voltage is applied. In the contact transfer type image forming apparatus to be transferred onto the transfer member, voltage output means for outputting a voltage value to be applied to the transfer member, and current detection means for monitoring the current flowing through the transfer member by the voltage output by the voltage output means And voltage control means for controlling the output voltage of the voltage output means based on detection information from the current detection means, wherein the voltage control means includes the following first voltage control mode and second voltage control. An image forming apparatus having a mode.
First voltage control mode: a predetermined target current determined in advance by the current detection means from a low output state of the voltage output means in a non-passage period in which the recording medium does not pass between the image carrier and the transfer member The voltage is sequentially increased until a value is detected, and from the voltage output value when it is determined that the predetermined target current has been reached, when the recording medium passes between the image carrier and the transfer member, A voltage control mode for determining an output voltage value of the voltage output means when the recording medium is not passing between the image carrier and the transfer member.
Second voltage control mode: In a non-passing period in which the recording medium does not pass between the image carrier and the transfer member, the recording medium is determined between the image carrier and the transfer member in the first voltage control mode. Based on the result of comparing the information from the current detection means at the time of output and the target current with respect to the output voltage when not passing through the non-passing output voltage, at least the recording medium passes between the image carrier and the transfer member. A voltage control mode for correcting the output voltage value of the voltage output means during passage. Is described.
[0014]
[Problems to be solved by the invention]
In the differential constant current method, since the output current of the transfer bias power supply is sequentially changed in accordance with the resistance of the contact transfer member, the output current of the transfer bias power supply is sequentially controlled in view of the resistance of the contact transfer member. However, the optimum transfer current to be targeted depends on external parameters (environment, resistance, aging, part material characteristics), but transfer bias depends on external parameters (environment, resistance, aging, part material characteristics). The output current of the power supply cannot be sequentially controlled (feedback control).
[0015]
Originally, it is ideal to control the transfer current by sequentially detecting the target transfer current value. However, each time the resistance of the contact transfer member is detected, a constant bias voltage or bias current is applied to the contact transfer member, and the current or voltage of the contact transfer member is detected and converted to the resistance value of the contact transfer member. It is necessary to always apply a bias to the contact transfer member, and it takes time to detect the resistance of the contact transfer member.
[0016]
In addition, since it is not known how the resistance of the contact transfer member behaves, it is not possible to perform simple feedback control in which the temperature and humidity are directly detected by a temperature and humidity sensor and the transfer current is immediately controlled based on the detected value. . That is, at present, only the resistance of the contact transfer member is detected and the transfer current is controlled. However, when the resistance of the contact transfer member changes abruptly over time or in the environment, there is a problem that it cannot follow it.
[0017]
For example, when a material whose resistance varies greatly due to environmental changes is used for the contact transfer member, the transfer current cannot be set to an optimum value as soon as the environment changes. In order to solve the above problem, when a method of detecting the resistance of the contact transfer member in a complicated manner is adopted, the user cannot be satisfied in terms of machine productivity.
[0018]
When the toner image is transferred with the transfer current set in the environment before the change, there is a problem that an abnormal image is generated when the environment is significantly changed. In particular, in a contact transfer member made of a material whose resistance varies depending on the environment such as an ion conductive system, when the temperature is changed from high temperature and high humidity (hereinafter referred to as H / H) to low temperature and low humidity (hereinafter referred to as L / L). If the electrophotographic current is set at H / H, an abnormal image is generated at L / L.
[0019]
In addition, when there is a sudden change from L / L to H / H, the transfer charge becomes insufficient. Further, the transportability of the sheet such as transfer paper (separability from the image carrier such as the photosensitive member) is not ensured, and the sheet is jammed. Even if the environment changes to such an extent that jam does not occur, the sheet is separated from the image carrier by the nail, so that there is a problem that a nail mark is generated in the image on the sheet.
In addition, contact transfer members made of materials whose resistance fluctuates over time have a large change in resistance in the initial state such as when the device arrives or when the contact transfer member is replaced. Control is required.
[0021]
  The present inventionAn object of the present invention is to provide an image forming apparatus capable of performing optimum transfer current control according to the characteristics of the contact transfer member and capable of performing more stable optimum transfer current control.
[0023]
[Means for Solving the Problems]
  In order to achieve the above object, an invention according to claim 1 is directed to an image carrier that carries a toner image, and contact transfer that transfers a toner image on the image carrier to a sheet that passes between the image carrier and the image carrier. Member and transfer bias to this contact transfer memberCurrentIn the image forming apparatus having a bias applying means for applying a resistance, a bias application change amount of the resistance of the contact transfer member, a time change amount of the resistance of the contact transfer member, and the contact transfer memberoverallresistanceFirst temperature detecting means for detecting temperature, humidity detecting means for detecting temperature and humidity, usage time detecting means for detecting the usage time of the contact transfer member, and the contact transfer member detected by the usage time detecting means. The storage means for storing the relationship between the usage time, the temperature / humidity detected by the temperature / humidity detection means and the transfer bias current of the contact transfer member, and the contact transfer member detected by the first detection means. It is determined whether or not the overall resistance is smaller than a predetermined value. If the overall resistance of the contact transfer member is smaller than the predetermined value, the data stored in the storage means is referred to The amount of change in bias applied to the contact transfer member detected by the first detection means, the amount of change in resistance of the contact transfer member over time, the temperature / humidity detected by the temperature / humidity detection means, and the usage time detection Use time of the contact transfer member that has detected the stageDepending on the transfer biasCurrentVariableWhen the overall resistance of the contact transfer member is larger than the predetermined value, the resistance of the contact transfer member detected by the first detection unit is referred to data stored in the storage unit Bias application change amount, time change amount of resistance of the contact transfer member, temperature and humidity detected by the temperature and humidity detection means, and use time of the contact transfer member detected by the use time detection meansDepending on the transfer biasCurrentTheThe overall resistance of the contact transfer member is variable to a transfer bias current different from the case where the resistance is smaller than the predetermined value.Transfer bias variable meansWhenIt is equipped with.
[0024]
  The invention according to claim 2In a contact transfer device of an image forming apparatus having an image carrier for carrying a toner image and transferring the toner image on the image carrier to a sheet, the image carrier to a sheet passing between the image carrier A contact transfer member for transferring the toner image on the upper surface; bias applying means for applying a transfer bias current to the contact transfer member; a bias application change amount of the resistance of the contact transfer member; and a time change amount of the resistance of the contact transfer member. A first detecting means for detecting the overall resistance of the contact transfer member, a temperature / humidity detecting means for detecting temperature / humidity, a use time detecting means for detecting a use time of the contact transfer member, and the use time detection. A memory in which data relating to the usage time of the contact transfer member detected by the means, the temperature / humidity detected by the temperature / humidity detection means, and the transfer bias current of the contact transfer member is stored in advance. If the overall resistance of the contact transfer member detected by the first detection means is smaller than a predetermined value, and if the overall resistance of the contact transfer member is smaller than the predetermined value, , Referring to the data stored in the storage means, the bias application change amount of the resistance of the contact transfer member detected by the first detection means, the time change amount of the resistance of the contact transfer member, the temperature and humidity Temperature / humidity detected by the detection means and use time of the contact transfer member detected by the use time detection meansDepending on the transfer biasCurrentVariableWhen the overall resistance of the contact transfer member is larger than the predetermined value, the resistance of the contact transfer member detected by the first detection unit is referred to data stored in the storage unit Bias application change amount, time change amount of resistance of the contact transfer member, temperature and humidity detected by the temperature and humidity detection means, and use time of the contact transfer member detected by the use time detection meansDepending on the transfer biasCurrentTheThe overall resistance of the contact transfer member is variable to a transfer bias current different from the case where the resistance is smaller than the predetermined value.Transfer bias variable meansAnd withIs.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
  FIG. 3 shows the first aspect of the present invention.Reference example1 and FIG. 2 show the firstReference exampleThe state at the time of non-transfer and a part of transfer is shown. This firstReference examples are2 is an example of an image forming apparatus having a contact transfer device. This firstReference exampleAs shown in FIG. 3, in the transfer conveyance device 1 as a contact transfer device, a belt unit 2 is detachably supported with respect to the image forming apparatus main body 1A.
[0030]
The belt unit 2 includes a transfer belt 6 as a contact transfer member for transferring a toner image on a drum-shaped photosensitive member 3 as an image carrier onto a transfer sheet S as a sheet, and a driving roller 5 around which the transfer belt 6 is wound. And the driven roller 4, a contact / separation lever 9 that contacts and separates the transfer belt 6 with respect to the photosensitive member 3, a DC solenoid 8 that rotates the contact / separation lever 9, and an inner peripheral surface of the transfer belt 6. A bias roller 11 as an electrode for applying a transfer bias to the transfer belt 6 and a contact plate 13 as an electrode in contact with the transfer belt 6 are provided. The photoreceptor 3 is configured by providing a photosensitive layer on a conductor, for example, and the conductor is grounded.
[0031]
The image forming apparatus main body 1A is provided with a cleaning device 16 having a cleaning blade 16A for scraping off residual toner and paper waste on the transfer belt 6, and a high-voltage power source 12 for applying a transfer bias to the bias roller 11. The drive roller 5 has a gear 5b (see FIG. 4) that is linked to a belt drive motor 22 (see FIG. 9) as a drive unit (not shown), and is rotationally driven by the belt drive motor 22 via the gear 5b. The transfer belt 6 is rotationally driven by the drive roller 5 and moves in the transfer paper transport direction A at a position facing the photoconductor 3.
[0032]
As shown in FIG. 5, the transfer belt 6 is composed of two layers 6a and 6b. The electrical resistance measured according to JISK6911 is such that the surface resistance of the surface layer 6b is 1 × 10 8 Ω to 1 × 10 12 Ω when DC 100V is applied. The surface resistance of the inner layer 6a is set in a wide range of 1 order to 2 orders from 1 × 10 7 Ω to 1 × 10 9 Ω, and the volume resistivity of the transfer belt 6 is set to 5 × 10 8 Ω. It is set over a wide range of about 1 to 2 orders from cm to 5 × 10 10 Ω · Cm. The surface layer 6b is a coating layer with a low coefficient of friction, and has a high elongation rate until a crack is generated.
[0033]
The rollers 4 and 5 are rotatably supported by the support 7. The support body 7 can swing around the support shaft 5a of the roller 5 positioned downstream of the transfer position of the toner image from the photoreceptor 3 to the transfer paper S in the transfer paper transport direction A of the rollers 4 and 5. It has become. The support 7 moves the transfer belt 6 by the rotation of the contact / separation lever 9 to contact / separate the photoreceptor 3, and the contact / separation lever 9 is driven and transferred by a DC solenoid (SOL) 8 to transfer the belt 6. Rotate the position side. In other words, a contact / separation lever 9 is connected to the DC solenoid 8, and the contact / separation lever 9 is driven by a signal from a control plate 8A serving as a control means to rotate and move the support 7, thereby supporting the support. 7 brings the transfer belt 6 into and out of contact with the photoreceptor 3.
[0034]
The transfer sheet S is fed to a registration roller 10 from a sheet feeding device (not shown), and is sent to the transfer belt 6 by the registration roller 10 so that the toner image on the photoreceptor 3 and the leading end position are aligned. When the DC solenoid 8 is driven by the control plate 8A and the contact / separation lever 9 approaches the photosensitive member 3 side, the support member 7 brings the transfer belt 6 into contact with the photosensitive member 3 so that the transfer belt 6 and the photosensitive member 3 are in contact with each other. A transfer nip portion B is formed.
[0035]
As shown in FIG. 4, the driven roller 4 has both ends 4 a and 4 a formed in a taper shape in the axial direction to prevent the transfer belt 6 from being displaced. The driven roller 4 is a conductive roller made of metal or the like, but only supports the transfer belt 6 having an electrical resistance as described above, and is electrically connected directly to other conductive members. It is an example when it is not. Further, the driven roller 4 can be grounded. When the driven roller 4 is grounded, the driven roller 4 is connected to the transfer control plate 14 so that a current is fed back from the transfer belt 6 to the transfer control plate 14 as control means via the driven roller 4.
[0036]
Since the drive roller 5 has a function of increasing the gripping force with respect to the transfer belt 6 when the transfer belt 6 is driven, a material such as EPDM rubber, chloroplane rubber, or silicone rubber is selected. Further, the driving roller 5 can be a conductive roller without using rubber. It is also possible to return the feedback current from the roller 5 to the transfer control plate 14. In this case, the drive roller 5 is connected to the transfer control plate 14 so as to return a feedback current from the transfer belt 6 to the transfer control plate 14 via the drive roller 5.
[0037]
The bias roller 11 is provided so as to contact the inside of the transfer belt 6 on the downstream side of the roller 4 in the moving direction of the transfer belt 6. The bias roller 11 constitutes a contact electrode for applying a charge having a polarity opposite to the charging polarity of the toner on the photosensitive member 3 to the transfer belt 6, and is connected to a high-voltage power source 12 as a bias applying unit. The The contact plate 13 is disposed in contact with the lower inner surface of the transfer belt 6 that is not the transfer paper conveyance surface, in the vicinity of the driven roller 4, and suppresses charge injection to the transfer paper S upstream from the transfer nip portion. The contact plate 13 is an electrode for detecting the current flowing through the transfer belt 6 as a feedback current, and is connected to the transfer control plate 14. The transfer control plate 14 is connected to the feedback current from the contact plate 13 (the rollers 4 and 5 are connected). In this case, the feedback current from the rollers 4 and 5) is detected to control the supply current or applied voltage from the high voltage power source 12 to the bias roller 11.
[0038]
In this transfer / conveying apparatus 1, as shown in FIG. 2, the control plate 8A controls the DC solenoid 8 as the transfer sheet S is fed out from the registration roller 10, and the support 7 photosensitive the transfer belt 6. A transfer nip portion B having a width of 4 to 8 mm corresponding to a predetermined length is formed between the photosensitive member 3 and the transfer belt 6 along the conveying direction of the transfer sheet S.
[0039]
  On the other hand, the photoconductor 3 is a book.Reference exampleIn the case of an (analog copying machine), the surface is uniformly charged to, for example, −800 V by a charging unit (not shown), and then exposed by an exposure unit (not shown) to form an electrostatic latent image. As shown, it is developed by the developing device 18 to become a toner image. That is, the electrostatic latent image becomes a toner image by electrostatically attracting the positively charged toner 19 from the developing device 18 to the photosensitive member 3.
[0040]
Then, before reaching the transfer nip portion B, the photoreceptor 3 is neutralized by a pre-transfer neutralization lamp 15 as a pre-transfer neutralization unit, and the surface charge is weakened. In FIG. 6, the height of the charge is represented by the size of the circle. The transfer sheet S fed out from the registration roller 10 is conveyed by the transfer belt 6 and passes through the transfer nip B. In the transfer nip portion B, the toner on the photoreceptor 3 is transferred to the transfer sheet S on the transfer belt 6 by applying a transfer bias to the transfer belt 6 from the high voltage power source 12 via the bias roller 11.
[0041]
This transfer bias is applied to the bias roller 11 from the high-voltage power supply 12 in the range of 1.5 KV to -6.5 KV. Since the transfer bias current is controlled as follows, the transfer bias is variably set. That is, the current output from the high-voltage power supply 12 is expressed as I₁Current flowing from the transfer belt 6 to the ground and detected by the transfer control plate 14 is I₂The transfer control plate 14 is
I₁-I₂= Iout (where Iout is a constant value) (1)
By controlling the high-voltage power supply 12 so that₁To control. This is because the change in transfer efficiency is eliminated by stabilizing the surface potential on the transfer paper S regardless of changes in environmental conditions such as temperature and humidity and variations in the manufacturing quality of the transfer belt 6.
[0042]
That is, the current flowing through the transfer belt 6 and the transfer sheet S toward the photosensitive member 3 is regarded as Iout, so that the current flow to the transfer belt 6 can be easily caused by lowering or increasing the surface resistance of the transfer sheet S. This is to prevent the change in the length from affecting the separation performance and transfer performance of the transfer paper S.
[0043]
By the way, when the image transfer from the photoreceptor 3 to the transfer paper S is performed, the transfer paper S is charged simultaneously. Therefore, due to the relationship between the true charge of the transfer belt 6 and the separation charge generated on the transfer paper S side, the transfer paper S is electrostatically attracted onto the transfer belt 6 and separated from the photoreceptor 3 after transfer. This separation is facilitated by a peeling operation based on the strength of the waist of the transfer sheet S using the curvature separation of the photoreceptor 3.
[0044]
In such electrostatic adsorption, when the humidity becomes high due to a change in environmental conditions, a current easily flows through the transfer paper S, so that the transfer paper S cannot be separated well. Therefore, the resistance value of the surface layer 6b of the transfer belt 6 is set slightly higher so that the movement of the true charge to the transfer sheet S at the transfer nip B is delayed. Further, since the bias roller 11 is positioned downstream of the transfer nip portion B in the transfer sheet conveyance direction, the transfer of the true charge from the transfer belt 6 to the transfer sheet S is delayed, and the transfer sheet S, the photoconductor 3 and The electrostatic attraction relationship between the two is avoided.
[0045]
In this case, delaying the transfer of the true charge means that charge injection to the transfer paper S does not occur on the upstream side until the transfer paper S reaches the transfer nip B on the photosensitive member 3 side. For this reason, the transfer paper S is prevented from being wound around the photoconductor 3, and separation failure of the transfer paper S from the photoconductor 3 is also prevented.
[0046]
Further, it is better to select the transfer paper S having a small resistance change due to an environmental change, and an appropriate amount of carbon, zinc oxide or the like is added as a conductive material for controlling the resistance, and a rubber belt is used as an elastic belt. In this case, it is desirable to select a material having a low hygroscopic property and a stable resistance value, such as chloroprene rubber, EPDM rubber, silicone rubber, and epichlorohydrin rubber.
[0047]
Note that the value of the current Iout flowing to the photosensitive member 3 side is not unique, and can be reduced when the transfer paper conveyance speed is slow. It will be increased if is not used. When the transfer sheet S is not separated from the photoreceptor 3, the transfer sheet S is separated from the photoreceptor 3 by the separation claw 20.
[0048]
On the other hand, the transfer sheet S that has passed through the transfer nip B is conveyed along with the movement of the transfer belt 6 while being electrostatically attracted to the transfer belt 6, and is subjected to curvature separation at the drive roller 5. For this reason, the diameter of the drive roller 5 is set to 16 mm or less. When such a driving roller 5 is used, high-quality 45K paper (stiffness is 21 (cm^Three/ 100)) is possible to obtain an experimental result.
[0049]
The transfer sheet S separated from the transfer belt 6 at 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, and the toner image is fixed. . After the image transfer from the photosensitive member 3 to the transfer sheet S and the transfer sheet separation are completed, the excitation of the DC solenoid 8 is released by the control plate 8A, and the contact / separation lever 9 and the support 7 are returned to the original positions. By doing so, it is separated from the photoreceptor 3, and the surface is cleaned by the cleaning device 16.
[0050]
The cleaning device 16 includes a toner that moves from the surface of the photoreceptor 3 to the transfer belt 6 when the cleaning blade 16A slides on the transfer belt 6, toner that does not transfer to the transfer paper S, and adheres to the transfer belt 6. Scrapes are scraped off the transfer belt 6 with a cleaning blade 16A.
[0051]
The transfer belt 6 rubbed by the cleaning blade 16A has a low fluorine resistance on the surface to prevent a phenomenon such as an increase in driving force due to an increase in the rubbing resistance or turning of the cleaning blade 16A. For example, it is coated with polyvinylidene fluoride, tetrafluoroethylene or the like. Further, the toner or paper scrapes scraped off from the surface of the transfer belt 6 by the cleaning blade 16A is accommodated in a waste toner collector (not shown) from the image forming apparatus main body 1A by the recovery screw 16B. The cleaning unit is the cleaning blade 16A, but it may be a cleaning roller to which a bias is applied.
[0052]
  By the way, bookReference exampleThen, the transfer belt 6 uses a plurality of types of transfer belts each composed of a material system having different tendencies. Conventionally, in an image forming apparatus having a contact transfer device, the transfer current is controlled only in accordance with a contact transfer member made of one kind of material, and each is made up of a plurality of materials that are technically different in nature. It has been difficult to master the multiple types of contact transfer members.
[0053]
If the material of the contact transfer member is one kind of material, the resistance can be detected inside the apparatus to control the transfer current. However, when a plurality of materials having different characteristics (for example, a carbon dispersion system, an ion conduction system, and a hybrid system) are used as a material for a contact transfer member in one image forming apparatus, the currently installed contact transfer member It is indispensable to understand what kind of tendency these materials have.
[0054]
  If the type of material is known, it is possible to grasp the behavior of the resistance of the material due to the change over time and the environment, and it becomes easy to perform the transfer current control matched to each system. For this purpose, the material detection of the contact transfer member is essential. In addition, if transfer belts made of a plurality of different materials are used, there is a cost advantage. So bookReference exampleDetects the time variation of the resistance of the transfer belt 6 as a contact transfer member to grasp the characteristics of the transfer belt 6, and performs transfer bias control based on the result.
[0055]
As a method for detecting the amount of change in resistance of the transfer belt 6 over time, for example, there are the following methods.
The first method is a method in which a constant voltage is applied to the transfer belt 6 and a current flowing through the transfer belt 6 is detected from immediately after the voltage application to a certain time later to detect the amount of change.
The second method is a method in which a constant current is supplied to the transfer belt 6 and the amount of change in the voltage of the transfer belt 6 is detected immediately after the current supply until a certain time later.
[0056]
  Here, the amount of change in resistance of the contact transfer member over time is the rate of change or difference between the current value immediately after voltage application to the contact transfer member and the current value after voltage application for a certain period of time, or the current supply of the contact transfer member It is the rate of change or difference between the voltage value immediately after and the voltage value after supplying the same current for a certain period of time. BookReference exampleThen, the amount of time change was set like the following formula.
  (Current value 1 minute after voltage application of contact transfer member−current value immediately after application of same voltage to contact transfer member) / (current value immediately after application of same voltage to contact transfer member)
  This is an example of the rate of change of the current value. The fixed time may be 2 minutes, 3 minutes, etc. instead of 1 minute.
[0057]
The change rate ΔIt of this current value is: ΔIt = (current value 1 minute after voltage application of the contact transfer member−current value immediately after application of the same voltage to the contact transfer member) / (current immediately after application of the same voltage to the contact transfer member) Value).
FIG. 7 shows an example of the time change amount of the resistance of the transfer belt 6. FIG. 7A is a representative example of the time variation of resistance of the transfer belt 6 constituted by the carbon dispersion system, and FIG. 7C is the resistance of the transfer belt 6 constituted by the ion conduction system. FIG. 7B shows a typical example of the time variation of resistance of the transfer belt 6 made of a hybrid material in which an ion conducting system and a carbon dispersion system are mixed. It is an example. From FIG. 7, by detecting the time change amount of the resistance of the transfer belt 6, the resistance change rate in each environment with respect to the resistance of the transfer belt 6 can be known.
[0058]
That is, it can be seen how much the resistance of the transfer belt 6 changes in each environment, and whether the material of the transfer belt 6 is an ion conductive material, a carbon dispersion material, or a hybrid system in which these are mixed. Or how close the material is to the ionic conduction system or the carbon dispersion system. Therefore, it is possible to accurately control the transfer current in each environment by detecting the time change amount of the resistance of the transfer belt 6.
[0059]
The present invention is not limited to the one that controls the transfer current by dividing the material of the transfer belt 6 into three material systems as described above. For example, taking a carbon dispersion as an example, comparing the case where a material having a polymer with a polar group is used as the material of the transfer belt 6 and the case where a normal polymer is used as the material of the transfer belt 6, Even if the amount and type of the conductive material are the same, the behavior of the material may be different. When a polymer having a large polarity is used as the material of the transfer belt 6, it may be closer to an ion conductive system.
[0060]
Compared to carbon dispersion materials, ion conductive materials have very large resistance environmental changes, and it is very difficult to control the transfer current in each environment. On the other hand, ion conductive materials have little resistance change with time (resistance change rate with time). If the resistance change with time is large, the material of the transfer belt 6 can be considered to be a carbon dispersion material. Carbon dispersion materials have a large amount of resistance change with time (resistance change rate with time), and it is very difficult to control transfer current with time.
[0061]
  For example, in the case of a transfer belt made of an ion conductive material, conventionally, the transfer current must be controlled by detecting the resistance of the transfer belt every time there is an environmental change. But bookReference exampleThen, once the resistance of the transfer belt 6 is detected, the resistance of the transfer belt 6 can be determined in each environment (how much the material of the transfer belt 6 is an ion conductive system, a carbon dispersion system, or a hybrid system). Therefore, it is not necessary to control the transfer current by detecting the resistance of the transfer belt 6 each time. It becomes possible to control the resistance of the transfer belt 6 by detecting the temperature and humidity by the temperature and humidity detecting means.
[0062]
FIG. 8 shows the relationship between temperature and humidity (here, L / L, normal temperature and normal humidity N / N, and H / H), the resistance change amount of the transfer belt 6 (time change amount of resistance), and the transfer current. . This is an example, and the resistance change amount (time change amount of resistance) and transfer of the transfer belt 6 each composed of temperature and humidity (3 environments of L / L, N / N, and H / H) and a plurality of types of materials. Current-related data is stored in the ROM in advance. Thereby, it is possible to detect the resistance change amount (resistance change amount of resistance) of the transfer belt 6 and control the transfer current based on the data in the ROM. This is particularly advantageous when there is a sudden environmental change. That is, here, as shown in FIG. 9, the environment (temperature and humidity) can be detected by the temperature / humidity detection means 21, and the transfer current can be sequentially changed by the transfer control plate 14 by the control plate 8A. Is advantageous. The control board 8A includes the CPU 23, the ROM 24, the RAM 25, the timer 26, and the I / Os 27 and 28, and is connected to the operation unit 29.
[0063]
Next, a carbon dispersion material will be described. This material has a resistance change over time larger than the resistance change in the environment, and it is indispensable to focus on the control of the transfer current over time. 10 to 12 show the relationship between the resistance change amount of the transfer belt with time T (resistance change amount with time) and the transfer current. Also in this case, the data of this relationship is stored in the ROM 24. Therefore, it is possible to detect the resistance change amount (resistance change amount of resistance) of the transfer belt 6 and control the transfer current by referring to the data in the ROM based on the resistance change amount. In particular, when there is not only a change with time but also a resistance change due to stretching as in the transfer belt 6, the transfer current can be controlled optimally over time. Note that the amount of resistance change is the order of 7th power or more in FIG. 10, the order of 8th to 9th power in FIG. 11, and the order of 10th power or more in FIG.
FIG. 13 shows the rate of change in resistance of the transfer belt 6 over time. The rate of change in resistance over time of the carbon dispersion system as shown in FIG. 13 (d) is greater than the rate of change in resistance over time of the ion conducting system as shown in FIG. 13 (e).
[0064]
FIG. 14 shows a flow from detection of the resistance of the transfer belt 6 and detection of the amount of change of the resistance over time to transfer current control. The control plate 8A first detects the resistance of the transfer belt 6 from the output voltage and output current of the high-voltage power supply 12 via the transfer control plate 14, and detects the amount of change in the resistance of the transfer belt 6 over time. Based on the amount of change over time, it is determined whether the material of the transfer belt 6 is an ion conductive system or a carbon dispersion system.
[0065]
When the detected value (resistance variation with time) is 0.5 or less, the control plate 8A performs transfer current control in the environment, that is, the input signal from the temperature / humidity detecting means 21 and the resistance variation with time (the resistance variation with time). The resistance change of the transfer belt 6 composed of data (temperature / humidity (3 environments of L / L, N / N, and H / H) as shown in FIG. The transfer current is changed to a transfer current corresponding to the environment (temperature and humidity) and the time change amount of the resistance (resistance change amount) with reference to the data of the relationship between the transfer amount and the transfer current). The operating time of the apparatus (usage time of the transfer belt 6) is measured by the time measuring means, and the data in the ROM 24 as shown in FIGS. 10 to 12 is calculated based on the time and the amount of change in resistance (resistance change amount). Referring to FIG. Current is changed to a transfer current corresponding to the time variation of the resistance (resistance change amount) and the operating time of the device (use time of the transfer belt 6).
[0066]
Further, when the detected value (resistance change over time) is larger than 0.5, the control plate 8A performs the transfer current control over time, that is, the operation time of the apparatus (the usage time of the transfer belt 6) and the above. By referring to the data in the ROM 24 as shown in FIGS. 10 to 12 according to the time change amount of resistance (resistance change amount), the transfer current is transferred to the transfer control board 14 by the time change amount (resistance change amount) of the resistance. The transfer current is changed according to the operation time of the apparatus (the usage time of the transfer belt 6).
[0067]
FIG. 15 shows a flow for detecting the resistance of the transfer belt 6. This flow corresponds to ☆ in FIG. The control plate 8A is I with respect to the transfer control plate 14.₁-I₂= Iout is set to 40 μA, the output voltage (transfer voltage applied to the transfer belt 6) V of the high-voltage power supply 12 is detected, and it is determined whether or not the voltage V is 2.0 kV or less. If the voltage V is 2.0 kV or less, the control plate 8A determines whether or not the voltage V is 1.0 kV or less. If the voltage V is 1.0 kV or less, the resistance of the transfer belt 6 is excessive. If the voltage V is not less than 1.0 kV, it is determined that the resistance of the transfer belt 6 is low.
[0068]
If the voltage V is not 2.0 kV or less, the control plate 8A has I with respect to the transfer control plate 14.₁-I₂= Iout is set to 50 μA, the output voltage V of the high-voltage power supply 12 is detected, and it is determined whether this voltage V is larger than 2.0 kV and smaller than 3.2 kV. The control plate 8A determines that the resistance of the transfer belt 6 is medium if the voltage V is greater than 2.0 kV and less than 3.2 kV, and if not 2.0 kV <V <3.2 kV, the transfer control plate 14. Against I₁-I₂= Iout is set to 60 μA, and the output voltage V of the high-voltage power supply 12 is detected.
[0069]
Then, the control plate 8A determines whether or not the voltage V is 3.2 kV <V ≦ 6.0 kV. If the voltage V is 3.2 kV <V ≦ 6.0 kV, it is determined that the resistance of the transfer belt 6 is high. If 3.2 kV <V ≦ 6.0 kV, the resistance of the transfer belt 6 is determined to be extremely high. The transfer belt has a high resistance in the initial state and tends to decrease with time. For this reason, when it is determined that the resistance of the transfer belt 6 is extremely high, there is a possibility that the output voltage of the high-voltage power supply 12 is abnormally high and leakage occurs from the transfer belt 6 to the photoreceptor 3. Therefore, when it is determined that the resistance of the transfer belt 6 is extremely high, the control plate 8A shifts to the flow shown in FIG. 16 and causes the transfer control plate 14 to switch from constant current control to constant voltage control. The constant voltage applied to the transfer belt 6 is preferably about 6.3 kV to 6.8 kV.
[0070]
That is, the control plate 8A detects the time change amount of the resistance of the transfer belt 6 from the output voltage and output current of the high-voltage power supply 12 via the transfer control plate 14, and based on the time change amount of the resistance. Whether the material is an ion conductive system or a carbon dispersion system. When the detected value (resistance variation with time) is 0.5 or less, the control board 8A determines whether or not the environment is L / L based on the input signal from the temperature / humidity detecting means 21, and the environment is L / L. If it is L, the flow proceeds to * in the flow shown in FIG. 14, but if the environment is not L / L, the transfer control plate 14 controls the output voltage of the high-voltage power supply 12 to a constant voltage of 6 kV.
[0071]
Further, when the detected value (resistance change amount of time) is larger than 0.5, the control plate 8A has an operation time (usage time of the transfer belt 6) T of the device measured by the time measuring means of 50 hours (hr) or less. If T is not shorter than 50 hours, the process proceeds to * 1 in the flow shown in FIG. 14. If T is shorter than 50 hours, the output of the high-voltage power supply 12 is output to the transfer control board. The voltage is controlled to a constant voltage of 6 kV.
[0072]
In the above-described resistance detection of the transfer belt 6, the voltage of the transfer belt 6 is detected by detecting the voltage of the transfer belt 6 when a constant current is supplied to the transfer belt 6, but the voltage is applied to the transfer belt 6. The resistance of the transfer belt 6 may be obtained by detecting the current of the transfer belt 6 at that time.
[0073]
  This firstReference exampleAccording to the present invention, the control plate 8A and the transfer control plate 14 are provided as transfer bias variable means for detecting the time change amount of the resistance of the transfer belt 6 as the contact transfer member and changing the transfer bias according to the detected value. Therefore, optimum transfer current control (transfer bias control) can be performed according to the characteristics of the contact transfer member, and transfer bias sequential control can be performed. In particular, by detecting the amount of change in the resistance of the contact transfer member over time, it is possible to determine how much the contact transfer member is an ion conductive system or a carbon dispersion system, and a more accurate transfer bias. Control becomes possible.
[0074]
  The firstReference exampleAccording to this, the control plate 8A as a transfer bias variable means and transfer control for detecting the amount of time change of the resistance of the contact transfer member 6 and changing the transfer bias at least in the environment and / or over time according to the detected value. Since the plate 14 is provided, optimum transfer current control (transfer bias control) can be performed according to the material characteristics of the contact transfer member. In particular, the transfer bias control when using a contact transfer member made of an ion conductive material can be made more accurate to stabilize the transfer bias control in the environment. L / L prevents leakage, With H / H, it is possible to stabilize the sheet transportability. In addition, the transfer bias control when using a contact transfer member made of a carbon dispersion material can be made more accurate to stabilize the transfer bias control over time, and the resistance of the contact transfer member over time can be improved. It is possible to respond to changes in
[0075]
  Next, the second of the present inventionReference exampleWill be described. This secondReference examples are2 is an example of an image forming apparatus having a contact transfer device. This secondReference exampleThen, the firstReference exampleThe transfer bias is controlled by detecting the bias application change amount of the resistance of the contact transfer member.
[0076]
  The amount of change in bias applied to the resistance of the contact transfer member is a difference or rate of change in resistance of the contact transfer member detected when at least two or more biases are applied to the contact transfer member. SecondReference exampleIn this case, since the transfer bias is controlled by detecting the bias application change amount of the resistance of the contact transfer member, two parameters are detected.Reference exampleMore precise transfer bias control can be performed.
[0077]
Here, a constant voltage is applied as a bias to the contact transfer member to set the transfer current as a constant current. For example, a current value when a constant voltage of 1 KV is applied to the contact transfer member as a bias is detected, and a constant voltage of 2 KV is applied to the contact transfer member to detect the current value at that time. The rate of change of these current values is calculated and the rate of change is detected. In this case, the current value is detected after a bias is applied for a certain period of time, and is made constant regardless of the applied voltage. For example, the predetermined time is set in advance such as 1 minute.
[0078]
  FIG. 17 shows the secondReference example4 shows a flow from detection of the bias application change amount of the resistance of the transfer belt 6 to transfer current control. The control plate 8A makes the output voltage (transfer bias) of the high-voltage power supply sequentially 100, 500, 1KV, 2KV with respect to the transfer control plate 14, and detects the current flowing through the transfer belt 6 when each transfer bias is applied. After converting these currents into the resistance of the transfer belt 6, a change rate ΔIv as a bias application change amount of the resistance of the transfer belt 6 is calculated from these resistances.
[0079]
Next, the control plate 8A recognizes what type of material the material of the transfer belt 6 is based on the difference in change rate, that is, recognizes whether the material of the transfer belt 6 is an ion conductive system or a carbon dispersion system, and performs transfer control. The transfer current Iout is varied with respect to the plate 14 for each material system. That is, when ΔIv is smaller than 0.5, the control plate 8A sets the correction coefficient to 0.8 for L / L and to 1.2 for H / H. To determine whether the environment is H / H or L / L. When the environment is H / H, the control plate 8A causes the transfer control plate 14 to correct the transfer current Iout by 1.2 times with a correction coefficient, and outputs the transfer bias from the high-voltage power supply 12, so that the environment is L / L. In the case of L, the transfer current is corrected by 0.8 times with a correction coefficient with respect to the transfer control plate 14 and the transfer bias is output from the high voltage power source 12, and when the environment is neither H / H nor L / L. The transfer current is not corrected.
[0080]
Further, when ΔIv is 0.5 or more, the control plate 8A sets the correction coefficient to 0.9 for L / L and 1.1 to H / H, and the input signal from the temperature / humidity detecting means 21. To determine whether the environment is H / H or L / L. When the environment is H / H, the control plate 8A causes the transfer control plate 14 to correct the transfer current by a factor of 1.1 to output a transfer bias from the high-voltage power supply 12, and the environment is L / L. In this case, the transfer current is corrected to 0.9 times with respect to the transfer control plate 14 and a transfer bias is output from the high-voltage power supply 12. If the environment is neither H / H nor L / L, the transfer current is corrected. No.
[0081]
  This secondReference exampleAccording to the present invention, the control plate 8A and the transfer control plate 14 are provided as transfer bias variable means for detecting a bias application change amount of the resistance of the transfer belt 6 as a contact transfer member and changing the transfer bias according to the detected value. Therefore, optimum transfer current control (transfer bias control) can be performed according to the characteristics of the contact transfer member, and transfer bias sequential control can be performed. In particular, by detecting the amount of change in bias applied to the resistance of the contact transfer member, it is possible to determine how much the contact transfer member is an ion conductive system or a carbon dispersion system, and a more accurate transfer bias. Can be controlled.
  SecondReference exampleAccording to the above, the control plate 8A as a transfer bias variable means that detects the bias application change amount of the resistance of the contact transfer member 6 and changes the transfer bias at least in the environment and / or over time according to the detected value and the transfer Since the control plate 14 is provided, optimum transfer current control (transfer bias control) can be performed according to the material characteristics of the contact transfer member. In particular, the transfer bias control when using a contact transfer member made of an ion conductive material can be made more accurate to stabilize the transfer bias control in the environment. L / L prevents leakage, With H / H, it is possible to stabilize the sheet transportability. In addition, the transfer bias control when using a contact transfer member made of a carbon dispersion material can be made more accurate to stabilize the transfer bias control over time, and the resistance of the contact transfer member over time can be improved. It is possible to respond to changes in
[0082]
  Next, the third of the present inventionReference exampleWill be described. This thirdReference examples are2 is an example of an image forming apparatus having a contact transfer device. This thirdReference exampleThen, the firstReference example, The bias application change amount ΔIv of the contact transfer member resistance and the time change amount ΔIt of the contact transfer member resistance are detected to control the transfer bias over the environment and time.
[0083]
18 to 21 show the relationship between the time T of the transfer belt of each material system, the environment, and the transfer current. Data on this relationship is stored in the ROM 24. The material system of rubber resistance constituting the transfer belt 6 is divided into four cases,
(1) When ΔIv <0.5 and ΔIt <0.5, ion conductive system
(2) Hybrid system when ΔIv <0.5 and ΔItT ≧ 0.5
(3) ΔIv ≧ 0.5 and ΔItT <0.5 are hybrid systems
(4) ΔIv ≧ 0.5 ΔIt ≧ 0.5 is carbon dispersion
And
[0084]
  FIG. 22 shows the thirdReference example2 shows a flow from detection of the bias application change amount of the resistance of the transfer belt 6 and time change amount of the resistance of the transfer belt 6 to transfer current control. The control plate 8A causes the transfer control plate 14 to sequentially increase the output voltage (transfer bias) of the high-voltage power supply 12 to 100, 500, 1 KV, and 2 KV, and detect the current flowing through the transfer belt 6 when each transfer bias is applied. Then, after converting these currents into the resistance of the transfer belt 6, a change rate ΔIv as a bias application change amount of the resistance of the transfer belt 6 is calculated from these resistances.
[0085]
Further, the control plate 8A applies a 2 kV transfer bias from the high-voltage power source 12 to the transfer belt 6 via the transfer control plate 14 for 30 seconds, 60 seconds, and 90 seconds for a certain period of time, and after applying the transfer bias for each certain time. After detecting the current flowing through the transfer belt 6 and converting these currents into the resistance of the transfer belt 6, a change rate ΔIt as a time change amount of the resistance of the transfer belt 6 is calculated from these resistances.
[0086]
Next, the control plate 8A recognizes what type of material the transfer belt 6 is based on the difference between the change rates ΔIv and ΔIt, that is, whether the material of the transfer belt 6 is an ion conductive system, a carbon dispersion system, or a hybrid. The transfer current Iout is varied for each material system with respect to the transfer control plate 14. That is, the control board 8A determines whether ΔIv is 0.5 or more and whether ΔIt is 0.5 or more.
[0087]
When ΔIv <0.5 and ΔIt <0.5, the control plate 8A determines that the material of the transfer belt 6 is an ion conductive system, and the input signal from the temperature / humidity detection means 21 and the time of the apparatus measured by the timekeeping means. By referring to the data in the ROM 24 as shown in FIG. 21 according to the operation time (use time of the transfer belt 6), the transfer current is set to the environment (temperature / humidity) and the operation time of the apparatus (transfer belt 6). The transfer current is changed according to the usage time of the printer.
[0088]
Further, the control plate 8A determines that the material of the transfer belt 6 is a hybrid system when ΔIv <0.5 and ΔIt ≧ 0.5, and the apparatus measured by the input signal from the temperature / humidity detecting means 21 and the time measuring means. Referring to the data in the ROM 24 as shown in FIG. 20 according to the operation time (use time of the transfer belt 6), the transfer current is set to the environment (temperature / humidity) and the operation time of the apparatus (transfer belt). 6), the transfer current is changed according to the usage time.
[0089]
Further, the control plate 8A determines that the material of the transfer belt 6 is a hybrid system when ΔIv ≧ 0.5 and ΔIt <0.5, and receives the input signal from the temperature / humidity detecting means 21 and the time measured by the time measuring means. Referring to the data in the ROM 24 as shown in FIG. 18 according to the operation time (use time of the transfer belt 6), the transfer current is set to the environment (temperature / humidity) and the operation time of the apparatus (transfer belt). 6), the transfer current is changed according to the usage time.
[0090]
Further, the control plate 8A determines that the material of the transfer belt 6 is a carbon dispersion system when ΔIv ≧ 0.5 and ΔIt ≧ 0.5, and receives the input signal from the temperature / humidity detecting means 21 and the time measured by the time measuring means. By referring to the data in the ROM 24 as shown in FIG. 19 according to the operation time of the apparatus (use time of the transfer belt 6), the transfer current is set to the environment (temperature and humidity) and the operation time of the apparatus (transfer). The transfer current is changed according to the belt 6 usage time).
[0091]
  This thirdReference exampleAccording to this, the bias application change amount of the resistance of the transfer belt 6 as the contact transfer member and the time change amount of the resistance of the transfer belt 6 as the contact transfer member are detected, and the transfer bias is varied according to the detected value. Since the control plate 8A and the transfer control plate 14 are provided as transfer bias variable means, optimum transfer current control (transfer bias control) can be performed according to the characteristics of the contact transfer member, and the transfer bias is sequentially controlled. be able to. In particular, by detecting the bias application change amount of the resistance of the contact transfer member and the time change amount of the resistance of the contact transfer member, to what extent the contact transfer member is an ion conductive system, or a carbon dispersion system, It is possible to grasp whether the system is a hybrid system, and it is possible to control the transfer bias more accurately.
[0092]
  The thirdReference exampleAccording to this, the bias application change amount of the resistance of the contact transfer member 6 and the temporal change amount of the resistance of the transfer belt 6 as the contact transfer member are detected, and the transfer bias is set to at least the environment and / or according to the detected value. ) Since the control plate 8A and the transfer control plate 14 are provided as transfer bias variable means that changes over time, optimum transfer current control (transfer bias control) can be performed according to the material characteristics of the contact transfer member. In particular, the transfer bias control when using a contact transfer member made of an ion conductive material can be made more accurate to stabilize the transfer bias control in the environment. L / L prevents leakage, With H / H, it is possible to stabilize the sheet transportability. In addition, the transfer bias control when using a contact transfer member made of a carbon dispersion material can be made more accurate to stabilize the transfer bias control over time, and the resistance of the contact transfer member over time can be improved. It is possible to respond to changes in
[0093]
  Next, the present inventionFirstExamples will be described. thisFirstExampleThenThird aboveReference example, The bias application change amount ΔIv of the contact transfer member resistance, the time change amount ΔIt of the contact transfer member resistance, and the resistance of the contact transfer member are detected to control the transfer bias over the environment and time.
[0094]
  23 to 26 show the relationship between the time T of the transfer belt of each material system, the environment, and the transfer current. Data on this relationship is stored in the ROM 24. The material system of rubber resistance that constitutes the transfer belt 6 is the third type.Reference exampleAs in Fig. 4, there are four cases. FIG.FirstThe flow from the detection of the bias application resistance change of the transfer belt 6, the time change amount of the resistance of the transfer belt 6 and the resistance of the contact transfer member to the transfer current control in the embodiment is shown.
[0095]
The control plate 8A causes the transfer control plate 14 to sequentially increase the output voltage (transfer bias) of the high-voltage power supply 12 to 100, 500, 1KV, and detect the current flowing through the transfer belt 6 when each transfer bias is applied. Is converted into the resistance of the transfer belt 6, and the change rate ΔIv as a bias application change amount of the resistance of the transfer belt 6 is calculated from these resistances.
[0096]
Then, the control plate 8A applies a 1 kV transfer bias from the high-voltage power supply 12 to the transfer belt 6 via the transfer control plate 14 for 30 seconds, 60 seconds, and 90 seconds for a certain time, and after applying the transfer bias for each certain time. After detecting the current flowing through the transfer belt 6 and converting these currents into the resistance of the transfer belt 6, a change rate ΔIt as a time change amount of the resistance of the transfer belt 6 is calculated from these resistances. Further, the control plate 8A applies a transfer bias of 2 kV from the high voltage power source 12 to the transfer belt 6 via the transfer control plate 14, detects the current flowing through the transfer belt 6, and uses this current as a resistance of the entire transfer belt 6. Convert to R.
[0097]
Next, the control plate 8A has a resistance R of the entire transfer belt 6 of 10.^TenIt is determined whether or not it is smaller than Ω, and the resistance R of the entire transfer belt 6 is 10^TenIf it is smaller than Ω, the process proceeds to A or less processing shown in FIG. Further, the control plate 8A has a resistance R of the entire transfer belt 6 of 10.^TenIf it is Ω or more, the material of the transfer belt 6 recognizes what type of material it is based on the difference between the change rates ΔIv and ΔIt, that is, recognizes whether the material of the transfer belt 6 is an ion conductive system, a carbon dispersion system, or a hybrid system. The transfer current Iout is varied for each material system with respect to the transfer control plate 14. That is, the control board 8A determines whether ΔIv is 0.5 or more and whether ΔIt is 0.5 or more.
[0098]
When ΔIv <0.5 and ΔIt <0.5, the control plate 8A determines that the material of the transfer belt 6 is an ion conductive system, and the input signal from the temperature / humidity detection means 21 and the time of the apparatus measured by the timekeeping means. With reference to the data in the ROM 24 as shown in FIG. 26 according to the operation time (use time of the transfer belt 6), the transfer current is set to the environment (temperature / humidity) and the operation time of the apparatus (transfer belt 6). The transfer current is changed according to the usage time of the printer.
[0099]
Further, the control plate 8A determines that the material of the transfer belt 6 is a hybrid system when ΔIv <0.5 and ΔIt ≧ 0.5, and the apparatus measured by the input signal from the temperature / humidity detecting means 21 and the time measuring means. Referring to the data in the ROM 24 as shown in FIG. 25 according to the operation time (use time of the transfer belt 6), the transfer current is set to the environment (temperature / humidity) and the operation time of the device (transfer belt). 6), the transfer current is changed according to the usage time.
[0100]
Further, the control plate 8A determines that the material of the transfer belt 6 is a hybrid system when ΔIv ≧ 0.5 and ΔIt <0.5, and receives the input signal from the temperature / humidity detecting means 21 and the time measured by the time measuring means. Referring to the data in the ROM 24 as shown in FIG. 23 according to the operation time (use time of the transfer belt 6), the transfer current is set to the environment (temperature / humidity) and the operation time of the apparatus (transfer belt). 6), the transfer current is changed according to the usage time.
[0101]
Further, when ΔIv ≧ 0.5 and ΔIt ≧ 0.5, the control plate 8A determines that the material of the transfer belt 6 is a carbon dispersion system, and receives the input signal from the temperature / humidity detecting means 21 and the time measured by the time measuring means. By referring to the data in the ROM 24 as shown in FIG. 24 according to the operation time of the apparatus (use time of the transfer belt 6), the transfer current is set to the environment (temperature / humidity) and the operation time of the apparatus (transfer). The transfer current is changed according to the belt 6 usage time).
[0102]
  thisFirstAccording to the embodiment, the bias application change amount of the resistance of the transfer belt 6 as the contact transfer member, the temporal change amount of the resistance of the contact transfer member 6 and the resistance of the entire contact transfer member 6 are detected and the detected value is determined. Since the control plate 8A and the transfer control plate 14 are provided as transfer bias variable means for changing the transfer bias, the firstReference example-3rdReference exampleIn addition to the same effects as the above, by detecting the resistance of the entire contact transfer member, stable and precise transfer bias control can be performed regardless of the environment over time.
[0103]
  Next, each other of the present inventionReference examples andExamples will be described. theseReference examples andIn the embodiment, the firstReference Example to Third Reference Example andIn the embodiment, the correction amount of the transfer bias is varied. The transfer bias correction is the above first.Reference Example to Third Reference Example andThis is correction of transfer bias (change of transfer current) in the embodiment, and further, the amount of correction of transfer bias is varied as follows.
[0104]
That is, when the width of the transfer sheet S becomes small, the control plate 8A transfers the correction amount of the transfer bias in order to obtain an optimal transfer current by a signal from a sensor that detects the width of the transfer sheet S. Increase (correct) according to the width of the paper S. Here, the control plate 8A may be configured such that the correction amount can be varied over time and environment. When the control plate 8A forms an image on the back surface of the transfer paper S and corrects the transfer current at that time, the control plate 8A corrects the transfer current when the image is formed on the back surface of the transfer paper S. Alternatively, the correction amount may be varied. Further, the control plate 8A performs correction of the transfer current when an image is formed on the back surface of the transfer sheet S by changing the correction amount of the transfer bias, and a signal from a sensor that detects the width of the transfer sheet S. Thus, the correction amount of the transfer bias may be corrected according to the width of the transfer sheet S.
[0105]
  theseReference examples andIn the embodiment, the firstReference Example to Third Reference Example andIn the embodiment, since the control plate 8A and the transfer control plate 14 as the transfer bias variable means vary the correction amount of the transfer bias, more stable transfer current control can be achieved by varying not only the transfer current but also the correction amount. Is possible.
[0106]
In the above embodiment, a contact transfer device having a transfer belt as a contact transfer member is used. However, the present invention can also be applied to a case where a contact transfer device having a contact transfer member such as a transfer roller is used. The above embodiment is an example in which differential transfer current control is performed as transfer current control, but the present invention can also be applied to the case where simple constant current control or constant voltage control is performed as transfer current control. Further, the present invention can be applied even if the mechanical configuration and the transfer current control system are other than the above-described embodiments.
[0107]
【The invention's effect】
  As aboveThe present inventionAccordingly, optimum transfer current control can be performed according to the characteristics of the contact transfer member, and sequential control of the transfer bias can be performed. In particular, the amount of change in bias applied to the resistance of the contact transfer member and the time variation of the resistance of the contact transfer member.Measure amountBy knowing, it is possible to grasp how much the contact transfer member is an ion conductive system or a carbon dispersion system, and it is possible to control the transfer bias more accurately.Further, stable and precise transfer bias control can be performed regardless of the environment over time.
[Brief description of the drawings]
FIG. 1 shows the first of the present invention.Reference exampleIt is the schematic which shows the state at the time of the one part non-transfer.
Fig. 2Reference exampleIt is the schematic which shows the state at the time of transcription | transfer of a part of.
Fig. 3Reference exampleFIG.
[Fig. 4] FirstReference exampleIt is the schematic which shows a part of.
Fig. 5Reference example2 is a cross-sectional view showing a part of the transfer belt in FIG.
FIG. 6 FirstReference exampleIt is a figure for demonstrating operation | movement of.
Fig. 7Reference exampleIt is a figure which shows the time change rate of resistance of the transfer belt in FIG.
Fig. 8Reference exampleFIG. 6 is a diagram illustrating a relationship between temperature and humidity, resistance change amount of the transfer belt, and transfer current.
Fig. 9Reference exampleIt is a block diagram which shows the control system of.
Fig. 10Reference exampleFIG. 6 is a diagram illustrating a relationship between a resistance change amount of a transfer belt with time T and a transfer current.
Fig. 11Reference exampleFIG. 6 is a diagram illustrating a relationship between a resistance change amount of a transfer belt with time T and a transfer current.
Fig. 12Reference exampleFIG. 6 is a diagram illustrating a relationship between a resistance change amount of a transfer belt with time T and a transfer current.
FIG. 13 FirstReference exampleIt is a figure which shows the resistance change rate with time of the transfer belt in FIG.
Fig. 14Reference example6 is a flowchart showing a flow from detection of the resistance of the transfer belt and detection of the amount of change in the resistance over time to transfer current control.
FIG. 15 FirstReference example6 is a flowchart showing a flow of detecting the resistance of the transfer belt in FIG.
Fig. 16Reference example5 is a flowchart showing a part of a transfer current control flow in FIG.
FIG. 17 shows the second of the present invention.Reference example5 is a flowchart showing a flow from detection of a bias application change amount of transfer belt resistance to transfer current control in FIG.
FIG. 18 shows the third of the present invention.Reference exampleFIG. 6 is a diagram showing the relationship between the time T of the transfer belt of each material system, the environment, and the transfer current.
FIG. 19Reference exampleFIG. 6 is a diagram showing the relationship between the time T of the transfer belt of each material system, the environment, and the transfer current.
FIG. 20Reference exampleFIG. 6 is a diagram showing the relationship between the time T of the transfer belt of each material system, the environment, and the transfer current.
FIG. 21Reference exampleFIG. 6 is a diagram showing the relationship between the time T of the transfer belt of each material system, the environment, and the transfer current.
FIG. 22Reference example5 is a flowchart showing a flow from detection of a bias application change amount of a transfer belt resistance and time change amount of a transfer belt resistance to transfer current control.
FIG. 23 shows the present invention.FirstIt is a figure which shows the relationship of the time T of the transfer belt of each material type | system | group in an Example, an environment, and a transfer current.
FIG. 24FirstIt is a figure which shows the relationship of the time T of the transfer belt of each material type | system | group in an Example, an environment, and a transfer current.
FIG. 25FirstIt is a figure which shows the relationship of the time T of the transfer belt of each material type | system | group in an Example, an environment, and a transfer current.
FIG. 26FirstIt is a figure which shows the relationship of the time T of the transfer belt of each material type | system | group in an Example, an environment, and a transfer current.
FIG. 27First6 is a flowchart showing a flow from detection of a transfer belt resistance bias change amount, a time change amount of transfer belt resistance, and resistance of the entire contact transfer member to transfer current control in the embodiment.
[Explanation of symbols]
  1 Transfer conveyor
  3 Photoconductor
  6 Transfer belt
  8A control board
  11 Bias roller
  12 High voltage power supply
  14 Transfer control board
  21 Temperature / humidity detection means

Claims (2)

An image carrier that carries a toner image, a contact transfer member that transfers the toner image on the image carrier to a sheet that passes between the image carrier, and a bias that applies a transfer bias current to the contact transfer member In an image forming apparatus having an application unit,
First detection means for detecting a bias application change amount of the resistance of the contact transfer member, a temporal change amount of the resistance of the contact transfer member, and an overall resistance of the contact transfer member ;
Temperature and humidity detecting means for detecting temperature and humidity;
A use time detecting means for detecting a use time of the contact transfer member;
Storage means for storing in advance data on the relationship between the use time of the contact transfer member detected by the use time detection means, the temperature and humidity detected by the temperature and humidity detection means, and the transfer bias current of the contact transfer member;
It is determined whether the overall resistance of the contact transfer member detected by the first detection means is smaller than a predetermined value. If the overall resistance of the contact transfer member is smaller than the predetermined value, the memory is stored. With reference to the data stored in the means, the bias application change amount of the resistance of the contact transfer member detected by the first detection means, the time change amount of the resistance of the contact transfer member, the temperature / humidity detection means When the transfer bias current is varied according to the detected temperature and humidity and the use time of the contact transfer member detected by the use time detecting means, and the overall resistance of the contact transfer member is larger than the predetermined value , Referring to data stored in the storage means, a bias application change amount of the resistance of the contact transfer member detected by the first detection means, a time change amount of the resistance of the contact transfer member, the temperature Degree detecting means detects the temperature and humidity, and the transfer bias current in accordance with the use time of the contact transfer member that has detected the use time detecting means, when the overall resistance of the contact transfer member is less than the predetermined value image type forming apparatus comprising the <br/> a transfer bias varying means for varying the different transfer bias current and. In a contact transfer device of an image forming apparatus having an image carrier that carries a toner image and transferring the toner image on the image carrier to a sheet,
A contact transfer member for transferring a toner image on the image carrier to a sheet passing between the image carrier and the image carrier;
Bias applying means for applying a transfer bias current to the contact transfer member;
First detection means for detecting a bias application change amount of the resistance of the contact transfer member, a temporal change amount of the resistance of the contact transfer member, and an overall resistance of the contact transfer member;
Temperature and humidity detecting means for detecting temperature and humidity;
A use time detecting means for detecting a use time of the contact transfer member;
Storage means for storing in advance data on the relationship between the use time of the contact transfer member detected by the use time detection means, the temperature and humidity detected by the temperature and humidity detection means, and the transfer bias current of the contact transfer member;
It is determined whether the overall resistance of the contact transfer member detected by the first detection means is smaller than a predetermined value. If the overall resistance of the contact transfer member is smaller than the predetermined value, the memory is stored. With reference to the data stored in the means, the bias application change amount of the resistance of the contact transfer member detected by the first detection means, the time change amount of the resistance of the contact transfer member, the temperature / humidity detection means When the transfer bias current is varied according to the detected temperature and humidity and the use time of the contact transfer member detected by the use time detecting means, and the overall resistance of the contact transfer member is larger than the predetermined value , Referring to data stored in the storage means, a bias application change amount of the resistance of the contact transfer member detected by the first detection means, a time change amount of the resistance of the contact transfer member, the temperature Degree detecting means detects the temperature and humidity, and the transfer bias current in accordance with the use time of the contact transfer member that has detected the use time detecting means, when the overall resistance of the contact transfer member is less than the predetermined value a transfer bias varying means for varying the different transfer bias current and
Contact transfer device characterized by comprising a.

Images