JP5076356B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a copying machine, a printer, a facsimile, and an image forming apparatus using an electrophotographic system having these functions. In particular, a toner image carried on the surface of an image carrier such as a photoconductor is transferred by a transfer roller. The present invention relates to an image forming apparatus that contacts and transfers to a transfer material, and an image forming apparatus that superimposes and transfers a plurality of color toner images formed on an intermediate transfer body onto a transfer material.

  As an image forming apparatus that contacts and transfers a toner image carried on the surface of a toner image carrier or the like onto a transfer material by a transfer roller, those described in Patent Documents 1 and 2 are known.

  In the color image forming apparatus disclosed in Patent Document 1, the transfer roller of the adjacent image forming unit on the downstream side passes through the conveyance belt after the leading end of the transfer material passes through the transfer position of the image forming unit on the upstream side. It is crimped to the drum.

The transfer device of Patent Document 2 includes a grounding member that comes in contact with and separates from the surface of a backup roll that supports the intermediate transfer member, and a bias roll that contacts and separates the backup roll via the intermediate transfer member and applies a transfer current during image formation. The earthing member contacts the backup roll at the time of transfer to ground the current, and moves to a position away from the backup roll at the time of non-image formation.
JP 2003-295577 A JP-A-9-62122

  The prior art of Patent Document 1 uses a transfer material conveyance belt and minimizes the time for pressure bonding a plurality of movable primary transfer rollers to an image carrier, and the temperature of the fixing roller of the fixing device of the present invention. This is different from the one that performs the transition and the pressure control of the secondary transfer roller.

  In the prior art of Patent Document 2, a grounding member that can be contacted and separated is disposed on a backup roll that supports an intermediate transfer member to prevent plastic deformation of the backup roll. The temperature of the fixing roller of the fixing device of the present invention is as follows. This is different from the one that performs the transition and the pressure control of the secondary transfer roller.

  These conventional techniques have a problem that it takes time to press the secondary transfer roller to the intermediate transfer member, and the first copy time is delayed.

  An object of the present invention is to shorten the first copy time and achieve high speed image forming processing.

The object is achieved by the invention described below.
1. An image carrier on which a toner image is formed, and an elastic roller which is rotatably supported and which is pressed against the image carrier via a transfer material and transfers the toner image formed on the image carrier to the transfer material And a fixing device that fixes the toner image to a transfer material onto which the toner image has been transferred by a fixing member. First, the elastic roller is pressed against and released from the image carrier. Drive means, second drive means for rotating the elastic roller, control means for controlling the operation of the first drive means and the second drive means, and detection for detecting the temperature of the fixing member a means, wherein the control means, the temperature detected by the detecting means and controlling said first drive means such that said elastic roller when more than a predetermined temperature and the image bearing member is crimped state, the Elastic roller and the image When the lifting member is crimped state, the elastic roller periodically controlling said second drive means so as to a certain amount of rotation of the temperature detected by the detecting means and the elastic roller when less than the predetermined temperature an image forming apparatus comprising Rukoto Gyosu control the first driving means so that a state of compression is released between the image bearing member.
2. An image carrier on which a toner image is formed, and an elastic roller which is rotatably supported and which is pressed against the image carrier via a transfer material and transfers the toner image formed on the image carrier to the transfer material And a fixing device that fixes the toner image to a transfer material onto which the toner image has been transferred by a fixing member. First, the elastic roller is pressed against and released from the image carrier. Drive means, second drive means for rotationally driving the elastic roller, and control means for controlling the operation of the first drive means and the second drive means. The first driving means is controlled to start the pressure-bonding of the elastic roller to the image carrier by starting temperature control to set the temperature of the fixing member to a predetermined temperature or higher, and the elastic roller and the image carrier are When in a crimped state In, the elastic roller periodically controlling said second drive means so as to a certain amount of rotation, and of the temperature of the fixing member to said image bearing member of the elastic roller by a temperature control start to be less than the predetermined temperature an image forming apparatus comprising control Gyosu Rukoto said first driving means so as to release the crimping.

  According to the present invention, it is possible to shorten the first copy time by omitting the time for starting the pressure-bonding of the transfer roller to the image carrier, thereby achieving a high-speed image forming process.

  In addition, it is possible to shorten the first copy time by omitting the time for starting the pressure bonding of the transfer roller to the image carrier, thereby achieving a high-speed image forming process.

  The present invention will be described below with reference to embodiments, but the present invention is not limited to the embodiments described below.

[Color image forming apparatus]
FIG. 1 is a cross-sectional view showing the overall configuration of a color image forming apparatus A according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the main part of the color image forming apparatus A.

  The color image forming apparatus A is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer member 7, primary transfer units 5Y, 5M, 5C, 5K, an intermediate transfer unit including secondary transfer means 8, a fixing device 11, and a paper feeding device 20.

  Above the color image forming apparatus A, an image reading apparatus B is installed. The document placed on the document table is scanned and exposed by the optical system of the document image scanning exposure apparatus of the image reading apparatus B, and read by the line image sensor. The analog signal photoelectrically converted by the line image sensor is subjected to analog processing, A / D conversion, shading correction, image compression processing and the like in the image processing unit, and then input to the exposure means 3Y, 3M, 3C, 3K. .

  The image forming unit 10Y that forms a yellow (Y) image includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y disposed around the image carrier 1Y.

  The image forming unit 10M that forms a magenta (M) color image includes an image carrier 1M, a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 6M.

  The image forming unit 10C that forms a cyan (C) image includes an image carrier 1C, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 6C.

  The image forming unit 10K that forms a black (K) image includes an image carrier 1K, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a cleaning unit 6K.

  The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit.

  As the image bearing members 1Y, 1M, 1C, and 1K, known ones such as an OPC photosensitive member and an aSi photosensitive member are used. An OPC photosensitive member is preferable, and in particular, a negatively charged OPC photosensitive member is preferable. In the form, negatively chargeable OPC is used.

  As the charging means 2Y, 2M, 2C, 2K, a corona discharge means such as a scorotron or a corotron is used, and a scorotron discharge means is preferably used.

  As the exposure means 3Y, 3M, 3C, and 3K, light emitting elements that emit light according to image data, such as lasers and LED arrays, are used.

  The belt-like intermediate transfer member 7 is semiconductive and is wound around a plurality of support rollers 71, 72, 73, 74 and a backup roller 75, and is supported so as to be able to circulate. In the present embodiment, the intermediate transfer member 7 is supported between the support rollers 73 and 74 in a planar shape.

  The images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred (primary transfer) and synthesized on the rotating intermediate transfer body 7 by the primary transfer means 5Y, 5M, 5C, and 5K. A color image is formed.

  The transfer material P accommodated in the paper feeding cassette 21 of the paper feeding device 20 is fed by a paper feeding means (first paper feeding unit) 22, and is fed with paper feeding rollers 23, 24, 25 and registration rollers (second feeding). The paper is conveyed to the secondary transfer means 8 through the paper portion 26 and the like, and the color image is transferred onto the transfer material P (secondary transfer).

  The transfer material P on which the color image has been transferred is subjected to heat and pressure by the fixing device 11 so that the color toner image (or single color toner image) on the transfer material P is fixed and fixed on the transfer material P. The paper is discharged from the paper roller 27 and placed on a paper discharge tray 28 outside the apparatus.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer unit 8, the residual toner is removed by the cleaning unit 6A from the intermediate transfer body 7 from which the transfer material P is separated by curvature.

[Primary transfer means]
The primary transfer means 5Y for transferring a yellow image is composed of a primary transfer roller 5YA and a DC power source 5YE for applying a voltage to the primary transfer roller 5YA. The primary transfer roller 5YA is opposed to the image carrier 1Y with the intermediate transfer member 7 interposed therebetween, and is in sliding contact with the inner surface of the intermediate transfer member 7. The DC power supply 5YE is grounded.

  The primary transfer means 5M for transferring a magenta color image includes a primary transfer roller 5MA and a DC power source 5ME for applying a voltage to the primary transfer roller 5MA. The primary transfer roller 5MA faces the image carrier 1M through the intermediate transfer member 7 and is in sliding contact with the inner surface of the intermediate transfer member 7. The DC power source 5ME is grounded.

  The primary transfer means 5C for transferring a cyan image is composed of a primary transfer roller 5CA and a DC power source 5CE for applying a voltage to the primary transfer roller 5CA. The primary transfer roller 5CA is opposed to the image carrier 1C with the intermediate transfer member 7 interposed therebetween, and is in sliding contact with the inner surface of the intermediate transfer member 7. The DC power supply 5CE is grounded.

  The primary transfer means 5K for transferring a black image is composed of a primary transfer roller 5KA and a DC power supply 5KE for applying a voltage to the primary transfer roller 5KA. The primary transfer roller 5KA is opposed to the image carrier 1K through the intermediate transfer member 7 and is in sliding contact with the inner surface of the intermediate transfer member 7. The DC power supply 5KE is grounded.

  A current value of 40 μA and a voltage value of +1.5 kV are applied to the DC power supplies 5YE, 5ME, 5CE, and 5KE of the primary transfer units 5Y, 5M, 5C, and 5K.

  Further, the primary transfer units 5Y, 5M, 5C, and 5K are moved by a driving unit (not shown) and retracted away from the inner surface of the intermediate transfer body 7 except during the primary transfer.

[Secondary transfer means]
The secondary transfer unit 8 includes a backup roller 75, a secondary transfer roller 8A, a DC power source 8E, and the like. The backup roller 75 made of a conductive material faces the secondary transfer roller 8 </ b> A through the intermediate transfer body 7 and is in sliding contact with the inner surface of the intermediate transfer body 7.

  The backup roller 75 is connected to a DC power source 8E that applies a DC voltage. A current value of 50 μA and a voltage value of +3 kV are applied to the DC power supply 8E of the secondary transfer unit 8. The DC power supply 8E transfers the residual toner attached to the secondary transfer roller 8A in contact with the intermediate transfer body 7 to the intermediate transfer body 7 by applying a reverse bias and cleans it.

  The backup roller 75 has substantially the same configuration as the primary transfer rollers 5YA, 5MA, 5CA, and 5KA, and is pressure-bonded to the inner surface side of the intermediate transfer body 7. The conductive backup roller 75 is formed by a roller body and an elastic layer formed on the surface of the roller body.

The intermediate transfer member 7 is a single layer or multilayer belt made of polyamide, polyimide, or the like, and has a volume resistivity of 10 ⁷ to 10 ¹² Ωcm.

  The intermediate transfer member 7 is secondarily transferred to the transfer material P by the secondary transfer unit 8 and then cleaned by passing through the cleaning unit 6A.

  The conductive secondary transfer roller 8A is formed of a roller body and an elastic layer formed on the surface of the roller body. The secondary transfer roller 8 </ b> A is moved by a driving unit (not shown) and retracted away from the surface of the intermediate transfer body 7 at times other than the secondary transfer.

  FIG. 3 is a cross-sectional view showing a main part of a color image forming apparatus according to another embodiment of the present invention. In addition, about the code | symbol used in drawing, the same code | symbol is attached | subjected to the part which has the same function as FIG. Further, differences from the above embodiment will be described.

  The secondary transfer means 8 includes a grounded backup roller 75, a secondary transfer roller 8A connected to a DC power supply 8E, an intermediate transfer body 7, and the like.

  The secondary transfer roller 8A is driven and rotated by the driving means 8B. The driving of the driving unit 8B is controlled by the control unit 8C.

  The outer peripheral length during rotation of the secondary transfer roller 8A in the pressure-bonded state is set to be equal to or smaller than the outer peripheral length of the backup roller 75 or the secondary transfer roller 8A having a short outer peripheral length.

[Fixing device]
2 and 3, a heating roller type fixing device 11 is disposed downstream of the secondary transfer unit 8 in the transfer material conveyance direction. The fixing device 11 heat-fixes the toner image transferred onto the transfer material P after the secondary transfer.

  The fixing device 11 includes a fixing roller 111 heated by a heating source 113, a pressure roller 112 heated by a heating source 114, and the like.

  Around the fixing roller 111, a cleaning means 115, a temperature sensor 116, a thermostat for preventing an abnormal temperature (not shown), and the like are arranged. A temperature sensor 117, a thermostat for preventing abnormal temperature, and the like are also arranged around the pressure roller 112.

  For the heating sources 113 and 114, a halogen lamp, induction heating means, or the like is used.

  The temperature sensor 116 detects the surface temperature of the fixing roller 111. Based on the detection signal of the temperature sensor 116, the control unit controls the surface temperature of the fixing roller 111 to a predetermined temperature.

  When the transfer material P is introduced into the fixing nip N where the fixing roller 111 and the pressure roller 112 are pressure-bonded, the heat of the fixing roller 111 heated by the heating source 113 is applied to the transfer material P, and the transfer material P is heated. The toner image is heated and fixed.

  2 and 3, the heating roller type fixing device 11 has been described. However, the fixing device according to the image forming apparatus of the present invention is not limited to this, and a fixing belt type or other fixing device is used. It also applies to the device.

[Roller arrangement of secondary transfer means 8]
FIG. 4 is a cross-sectional view showing the roller arrangement of the secondary transfer means 8.

  Transfer that is conveyed to a secondary transfer nip NP that presses against the backup roller 75 via the straight line connecting the center of the secondary transfer roller 8A and the center of the backup roller 75, and the secondary transfer roller 8A and the intermediate transfer body 7. The secondary transfer roller 8A was arranged so that the angle θ formed with the material P was 75 ° or less. The transfer material P, which carries the toner image t and is conveyed, enters the secondary transfer nip portion NP and is secondarily transferred in close contact with the intermediate transfer member 7.

  FIG. 5 is a cross-sectional view showing the secondary transfer nip portion NP between the backup roller 75 and the secondary transfer roller 8A.

  The roller portions of the backup roller 75 and the secondary transfer roller 8A were all made of polyurethane rubber or the like, and the rubber hardness difference between the rollers was set to 6 degrees as the maximum Asker C hardness. For example, the rubber hardness of each roller was set to 67 ° ± 3 °.

  FIG. 5A shows that the difference in rubber hardness between the backup roller 75 and the secondary transfer roller 8A is 0, that is, the rubber hardness of each roller is equal, for example, the rubber hardness of each roller is 67 °, or both. It shows a state in which the secondary transfer nip portion NP is formed in a flat shape with 70 ° or both set to 64 ° or the like.

  In FIG. 5B, the rubber hardness of the backup roller 75 is large, the rubber hardness of the secondary transfer roller 8A is small, for example, the rubber hardness of the backup roller 75 is 70 °, and the rubber hardness of the secondary transfer roller 8A is 64 °. In the secondary transfer nip portion NP, the backup roller 75 having a high rubber hardness bites into the rubber layer of the secondary transfer roller 8A having a low rubber hardness.

  FIG. 5C shows that the rubber hardness of the backup roller 75 is small, the rubber hardness of the secondary transfer roller 8A is large, for example, the rubber hardness of the backup roller 75 is 64 °, and the rubber hardness of the secondary transfer roller 8A is 70 °. In the secondary transfer nip portion NP, the secondary transfer roller 8A having a high rubber hardness has bitten into the rubber layer of the backup roller 75 having a low rubber hardness.

  In the pressure bonding between the backup roller 75 and the secondary transfer roller 8A, the transfer material entering the secondary transfer nip portion NP is set by setting the difference in rubber hardness between the rollers to 6 degrees as the maximum Asker C hardness. P is securely secondary-transferred closely to the intermediate transfer member 7.

  When the difference in rubber hardness between the rollers is 67 ° + 3 ° or more, the toner image carried on the intermediate transfer member 7 is strongly pressed in the secondary transfer nip portion NP, and an image defect occurs. Further, when the rubber hardness difference between the rollers becomes 67 ° -3 ° or less, a secondary transfer failure occurs in the secondary transfer nip portion NP.

  FIG. 6 is a cross-sectional view of the secondary transfer unit 8 having a cleaning member for cleaning the outer peripheral surface of the secondary transfer roller 8A. FIG. 6A shows a cleaning member 8F which is a cleaning blade having elasticity. FIG. 6B shows a cleaning member 8G which is a rotatable brush roller.

  These cleaning members 8F and 8G are applied with a predetermined load by a pressing means (not shown) only at the time of image formation, are in sliding contact with the outer peripheral surface of the secondary transfer roller 8A, and remain on the secondary transfer roller 8A. Remove and recover.

  On the outer periphery of the elastic layer of the secondary transfer roller 8A, a wear-resistant elastic layer is coated or coated.

[Image forming apparatus]
FIG. 7 is a cross-sectional view illustrating the image forming unit 10 of the image forming apparatus.

  Around the image carrier 1, a charging unit 2, an exposure unit 3, a developing unit 4, a transfer unit 9, and a cleaning unit 6 are arranged in the order of the image forming process.

  The transfer unit 9 includes a transfer roller 9A, a DC power source 9E, and the like. The conductive transfer roller 9A is formed by a rotating shaft and an elastic layer formed on the surface of the rotating shaft. Both ends of the rotating shaft are rotatably supported by the bearing 9B. The DC power source 9E cleans the toner remaining on the transfer roller 9A in contact with the image carrier 1 by transferring it to the image carrier 1 by applying a reverse bias.

  The transfer roller 9A of the image forming unit 10 starts to press the transfer roller 9A to the image carrier 1 when the detection temperature by the detection unit that detects the temperature of the fixing member of the fixing device is equal to or higher than a predetermined temperature. When the temperature is equal to or lower than the predetermined temperature, the pressure bonding of the transfer roller 9A to the image carrier 1 is released.

  Further, the transfer roller 9A of the image forming unit 10 starts to press the image carrier 1 when the temperature control of the fixing member of the fixing device is started, and the image carrier of the transfer roller 9A when the temperature control of the fixing member of the fixing device is released. Release crimping to 1.

[Secondary transfer roller control]
FIG. 8 is a block diagram showing the configuration of the control means of the transfer means 9 and the secondary transfer means 8.

  The control unit 8 </ b> C starts the fixing device 11 when the power is turned on in an operation unit (not shown) of the image forming apparatus A, and starts temperature control of the fixing device 11. Further, the control unit 8C performs pressure release cancellation of the secondary transfer roller 8A, rotational drive control, and transfer bias application control.

  When image formation is started from a power-off state, it takes time to set the fixing temperature to a predetermined temperature. During this time, the transfer roller 9A or the secondary transfer roller 8A is pressed.

  When the pressing of the transfer roller 9A or the secondary transfer roller 8A is started at idling, that is, when the temperature of the fixing member such as the fixing roller 111 and the pressure roller 112 of the fixing device 11 is within a certain range, the printout start time It will be late.

  In the present invention, when the fixing temperature is within a predetermined temperature or within a predetermined range, the transfer roller 9A or the secondary transfer roller 8A is pressed in advance to prepare for the print start, whereby the first Copy time is shortened.

  Further, when the fixing control temperature is within a certain range, the transfer roller 9A or the secondary transfer roller 8A is kept in a pressed state, the time during which it does not rotate is counted, and the distance within one round is periodically rotated. Thereby, permanent deformation of the transfer roller 9A or the secondary transfer roller 8A can be reduced.

  In the secondary transfer of the multicolor toner image by the intermediate transfer body 7 and the secondary transfer roller 8A, the toner adhesion amount of the intermediate transfer body 7 is large, and generally, the transfer can be sufficiently performed unless the pressing force is made stronger than the primary transfer. Can not. The pressing force may be 1 kgf (9.8 N) or more. When such a strong pressing force is applied, the secondary transfer roller 8A having elasticity that is always pressed against the intermediate transfer body 7 is plastically deformed. For this reason, it is necessary to create conditions that do not cause plastic deformation.

  In the region where the pressing force is 1 kgf or more, the solid rubber is less likely to be plastically deformed than a foamed elastic roller such as a sponge even when pressed with the same load. Further, the deformation amount can be reduced by setting the secondary transfer roller 8A and the backup roller 75 to substantially the same hardness. Further, in a state where the secondary transfer roller 8A and the backup roller 75 are pressure-bonded via the intermediate transfer body 7, the amount of deformation can be reduced by periodically rotating. As a result, the secondary transfer roller 8A was always pressed against the intermediate transfer body 7 without causing plastic deformation.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In this embodiment, an image is formed by the color image forming apparatus A provided with the primary transfer means 5Y, 5M, 5C, 5K and the secondary transfer means 8 shown in FIG.

[Image formation conditions]
Image forming apparatus: Tandem type full color copier (Konica Minolta 8050 (registered trademark) modified machine, see FIG. 1), continuous copying speed: full color mode, output 51 sheets per minute with A4 size transfer material Image carrier 1Y, 1M, 1C , 1K: Outer diameter φ60mm
Transfer line speed of transfer material P: 220 mm / sec
Developer: Carrier average particle size 20-60 μm, polymerization toner average particle size 3-7 μm
Charging means 2Y, 2M, 2C, 2K: charging voltage V0 is -700V (variable: standard values on the left)
Exposure means 3Y, 3M, 3C, 3K: semiconductor laser (wavelength 780 nm), image forming body surface potential Vi during exposure is -50V
Developing means 4Y, 4M, 4C, 4K: The developing sleeve potential Vdc is −500 V (variable: the standard value on the left), the developing bias voltage AC component Vac is 1 kVp-p rectangular wave (frequency 5 kHz),
Primary transfer rollers 5YA, 5MA, 5CA, 5KA: using conductive roller, roller pressing 50N (Newton), transfer current 40μA, transfer voltage + 1.5kV applied,
Secondary transfer means 8: The electrical resistance values of the backup roller 75 and the secondary transfer roller 8A are both 4 × 10 ⁷ Ω, and a predetermined current value is selected and applied from a current value table in which a matrix is formed of temperature and humidity and a counter. To do.

Pressing force F: 50 N (Newton), transfer material conveyance direction nip width: 3 mm,
Elastic layer of secondary transfer roller 8A: semiconductive NBR solid rubber (acrylonitrile butadiene rubber), surface coating of elastic layer, volume resistance 4 × 10 ⁷ Ω, outer diameter φ30 mm, rubber hardness 67 ° ± 3 °,
Axial length of the elastic layer of the secondary transfer roller 8A: LA = 150 mm, LB = 250 mm, LC = 330 mm,
Backup roller 75: electric resistance value 4 × 10 ⁷ Ω, volume resistance value 4 × 10 ⁷ Ω, outer diameter φ30 mm, rubber hardness 67 ° ± 3 °, surface coating of elastic layer,
Intermediate transfer body 7: polyimide resin, seamless semiconductive belt (volume resistivity 10 ⁹ Ωcm), tension tension 50N, linear velocity 220 mm / sec,
[Example 1]
The first embodiment is control of pressing of the secondary transfer roller 8 </ b> A against the intermediate transfer body 7 by the temperature of the fixing device 11.

  FIG. 9 is a time chart showing control of pressing and rotation of the secondary transfer roller 8A. FIG. 9A shows the temperature control transition of the fixing roller 111 of the fixing device 11, and FIG. 9B shows the timing of pressure bonding and release of the secondary transfer roller 8A to the intermediate transfer body 7. (C) shows the rotation timing of the secondary transfer roller 8A.

  The temperature control of the fixing device 11 is controlled by a detection signal of a temperature sensor 116 that detects the surface temperature of the fixing roller 111 shown in FIG.

  If the temperature of the fixing roller 111 is in the range of 200 ° C. ± 10 ° C., the secondary transfer roller 8A is pressure-bonded to the intermediate transfer body 7. If the temperature of the fixing roller 111 is out of the range of 200 ± 10 ° C., the pressure bonding to the intermediate transfer body 7 of the secondary transfer roller 8A is released by the driving means 8B.

  Further, the secondary transfer roller 8A is rotated at a rotation angle of about 30 ° by the driving means 8B after the stop time of 3 minutes has elapsed with the secondary transfer roller 8A being pressure-bonded. This rotation angle of 30 ° corresponds to an arc length of 7.85 mm when the outer diameter of the secondary transfer roller 8A is 30 mm.

  In the conventional image forming apparatus, since the press of the secondary transfer roller 8A to the intermediate transfer body 7 is started by the print start signal, the first copy of the A4 size transfer material P is printed out from turning on the start button. It took about 8 seconds. In the secondary transfer control of the present invention, the first copy time is shortened to about 4 seconds.

[Example 2]
The second embodiment is control of pressing of the secondary transfer roller 8 </ b> A to the intermediate transfer body 7 by the temperature change timing of the fixing device 11.

  FIG. 10 is a time chart showing control of pressing and rotation of the secondary transfer roller 8A. 10A shows the temperature control command value of the fixing device 11, FIG. 10B shows the temperature control transition of the fixing roller 111 of the fixing device 11, and FIG. 10C shows the secondary transfer roller 8A. The timing of pressure bonding to and release from the intermediate transfer body 7 is shown.

  When the temperature control of the fixing roller 111 is commanded within the range of 200 ° C. ± 10 ° C., the secondary transfer roller 8A is moved by the driving means 8B and is pressed against the intermediate transfer body 7. When the temperature control is changed outside the range of 200 ° C. ± 10 ° C., for example, when the image forming apparatus is switched off, switched to the power saving mode, etc., the secondary transfer roller 8A is moved by the driving means 8B to the intermediate transfer member. 7 apart.

  In the conventional image forming apparatus, since the press of the secondary transfer roller 8A to the intermediate transfer body 7 is started by the print start signal, the first copy of the A4 size transfer material P is printed out from turning on the start button. Although it took about 8 seconds, in the secondary transfer control of the present invention, the first copy time is shortened to about 4 seconds.

FIG. 3 is a cross-sectional view showing the overall configuration of the color image forming apparatus. FIG. 3 is a cross-sectional view illustrating a main part of the color image forming apparatus. Sectional drawing which shows the principal part of the color image forming apparatus which concerns on other embodiment. Sectional drawing which shows roller arrangement | positioning of a secondary transfer means. Sectional drawing which shows the secondary transfer nip part of a backup roller and a secondary transfer roller. Sectional drawing of the secondary transfer means which has a cleaning member. FIG. 3 is a cross-sectional view illustrating an image forming unit of the image forming apparatus. The block diagram which shows the structure of the control means of a transfer means and a secondary transfer means. 6 is a time chart showing control of pressing and rotation of a secondary transfer roller. 6 is a time chart showing control of pressing and rotation of a secondary transfer roller.

Explanation of symbols

1, 1Y, 1M, 1C, 1K Image carrier 5Y, 5M, 5C, 5K Primary transfer means 7 Intermediate transfer body 75 Backup roller (elastic roller)
8 Secondary transfer means 8A Secondary transfer roller (elastic roller)
8B Driving means 8C Control means 8E DC power supply 8F, 8G Cleaning member 9 Transfer means 9A Transfer roller 9B Bearing 9E DC power supply 11 Fixing device 111 Fixing roller (fixing member)
112 Pressure roller (fixing member)
116, 117 Temperature sensor 20 Paper feeding device A Color image forming device N Fixing nip NP Secondary transfer nip

Claims (10)

An image carrier on which a toner image is formed;
An elastic roller that is rotatably supported and that is pressed against the image carrier via a transfer material and transfers a toner image formed on the image carrier to the transfer material;
A fixing device that fixes the toner image to a transfer material onto which the toner image has been transferred by a fixing member;
First driving means for pressing and releasing the elastic roller to and from the image carrier;
Second driving means for rotationally driving the elastic roller;
Control means for controlling the operation of the first drive means and the second drive means;
Detecting means for detecting the temperature of the fixing member,
The control means controls the first driving means so that the elastic roller and the image carrier are in a pressure-bonded state when the temperature detected by the detection means is equal to or higher than a predetermined temperature, and the elastic roller and the image carrier And the elastic roller and the image when the temperature detected by the detecting means is lower than the predetermined temperature. an image forming apparatus comprising Rukoto Gyosu control the first driving means so that a state of compression is released with carrier. An image carrier on which a toner image is formed;
An elastic roller that is rotatably supported and that is pressed against the image carrier via a transfer material and transfers a toner image formed on the image carrier to the transfer material;
A fixing device that fixes the toner image to a transfer material onto which the toner image has been transferred by a fixing member;
First driving means for pressing and releasing the elastic roller to and from the image carrier;
Second driving means for rotationally driving the elastic roller;
Control means for controlling the operation of the first drive means and the second drive means,
The control means controls the first driving means to start the pressure-bonding of the elastic roller to the image carrier by starting temperature control to set the temperature of the fixing member to a predetermined temperature or higher, and the elastic roller and the When the image bearing member is in a pressure-bonded state, the second driving unit is controlled to periodically rotate the elastic roller by a certain amount, and temperature control is started so that the temperature of the fixing member is less than the predetermined temperature. an image forming apparatus comprising Rukoto Gyosu control the first driving means so as to release the crimping of the said image bearing member of the elastic roller.   The image carrier is an intermediate transfer member in which a toner image formed on the image carrier is primarily transferred by a primary transfer unit, and the toner image that has been primarily transferred is secondarily transferred to a transfer material. The image forming apparatus according to claim 1.   The elastic roller is a secondary transfer roller that is opposed to a backup roller that supports the intermediate transfer member via the intermediate transfer member and presses the intermediate transfer member via a transfer material. The image forming apparatus according to 3.   5. The image according to claim 4, wherein the backup roller and the secondary transfer roller are formed of a rubber member, and a difference in rubber hardness between these rollers is 6 degrees at the maximum in Asker C hardness. Forming equipment.   6. The outer peripheral length when the secondary transfer roller is rotated in a pressure-bonded state is equal to or less than an outer peripheral length of a short outer peripheral length of either the backup roller or the secondary transfer roller. The image forming apparatus described.   The image forming apparatus according to claim 4, wherein a secondary transfer voltage is applied to the backup roller.   The image according to any one of claims 1 to 7, wherein a cleaning member for cleaning an outer peripheral surface of the elastic roller is provided, and the cleaning member contacts the outer peripheral surface of the elastic roller during image formation. Forming equipment.   The image forming apparatus according to claim 8, wherein the cleaning member is an elastic blade.   The image forming apparatus according to claim 8, wherein the cleaning member is a rotatable brush roller.

Images