JP2006195004A - Image forming apparatus and its power supply control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize optimum printing density by appropriate transfer current (charge) control even in constitution for applying fixing bias. <P>SOLUTION: The image forming apparatus has a charging means for charging a drum 1, an exposure means for forming an electrostatic latent image on the drum, a developing means for developing the electrostatic latent image to be a toner image, a transfer means for transferring the toner image to recording material P, and a fixing means for fixing the toner image on recording material by holding and conveying the toner image on the recording material at least between a heating member 100 and a pressure member 11 having an elastic layer. The fixing means is provided with a bias voltage generation part 20 for applying bias voltage to the surface of at least either the heating member or the pressure member, a current detection part 208 for measuring a bias current value flowing in a conduction part for connecting the surface of the heating member or the pressure member with the bias voltage generation part, a transfer power supply control part for controlling the transfer power supply 300 of the transfer means according to the detected bias current value and/or a bias power supply control part for controlling the bias power supply 20 of the fixing means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and a power supply control method thereof, for example, an image forming apparatus using an electrophotographic process, such as a copying machine, a laser printer, a facsimile machine, etc., in particular, a charging means for charging an image carrier, and a static on the image carrier. At least a heating unit that heats at least an exposure unit that forms an electrostatic latent image; a developing unit that develops the electrostatic latent image as a toner image; a transfer unit that transfers the toner image onto a recording material; An image forming unit including a fixing unit configured to fix the toner image on the recording material by being nipped and conveyed by a member and a pressure member having an elastic layer, and the heating member supplies an AC voltage to realize a heating function. The present invention relates to a device and a power supply control method thereof.

  In a fixing device in this type of image forming apparatus, in a high-temperature and high-humidity environment, when the moisture content of the recording material such as paper is high, the transfer charge supplied to the back surface of the recording material at the transfer portion is transmitted along the recording material. And the toner image transferred and formed on the recording material is easily lost.

  In addition, when the moisture content of the recording material is large, the amount of steam generated at the fixing nip where the heater and the pressure roller sandwich the recording material increases. Especially in the horizontal line image perpendicular to the conveyance direction of the recording material, steam called tailing is generated. The toner was scattered due to the pressure of.

  In addition, since the toner image holding force due to the transfer charge on the back surface of the recording material is weakened, the toner is not fixed to the recording material, and the toner adheres to the fixing film or the fixing roller. An image defect in which the adhered toner is fixed to the recording material after one rotation is likely to occur. In addition, toner adheres to the fixing film due to an offset phenomenon, and is transferred to a pressure roller pressed against the fixing film, which causes pressure roller contamination.

Therefore, conventionally, in order to prevent image defects due to the generation of water vapor in the vicinity of the heating body, there is a method in which the fixing roller side is grounded and a voltage is applied to the electrode in contact with the recording material as disclosed in Patent Document 1, for example. Has been taken. Hereinafter, this voltage is referred to as a fixing bias.
Japanese Patent Laid-Open No. 08-272245

  However, in the method of supplying the fixing bias as described above, this application path becomes one of the leakage paths of the transfer voltage, which causes a decrease in the transfer voltage. Lowering the transfer voltage reduces the electric charge (current) for holding the toner image, so that the toner cannot be held on the recording material and an appropriate print density cannot be obtained.

  The present invention has been made to solve the above-described problems, and aims to achieve an optimal print density by controlling an appropriate transfer current (charge) even in a configuration in which a fixing bias is applied. To do.

  The present invention is an image forming apparatus having the following configuration.

  (1) Charging means for charging the image carrier, exposure means for forming an electrostatic latent image on the image carrier, developing means for developing the electrostatic latent image as a toner image, and recording the toner image Transfer means for transferring onto the material, and fixing means for fixing the toner image on the recording material by nipping and conveying the toner image on the recording material between at least a heating member and a pressure member having an elastic layer. In the image forming apparatus, the fixing unit includes a bias voltage generating unit for applying a bias voltage to at least one surface of the heating member or the pressure member, a surface of the heating member or the pressure member, and the bias voltage. And a current detecting means for measuring a bias current value flowing through the conductive means, and a current detection circuit is provided in an actual leakage path. And by, the fact that to measure the actual leakage currents and to detect the timing at which the leakage current path is formed by the recording material, it can perform control in synchronism with the timing.

  (2) The current detection means is provided between the insulation resistance and the bias voltage generation means after providing an insulation resistance on the surface side of the heating member or the pressure member.

  (3) The image forming apparatus further comprises transfer power supply control means for controlling the transfer power supply of the transfer means based on the bias current value detected by the current detection means, and controls the transfer voltage by detecting the bias current value. Accordingly, it is possible to realize appropriate transfer voltage supply and transfer control in consideration of transfer leakage current, as compared with conventional control of only transfer voltage or transfer current.

  (4) The image forming apparatus further includes detection means for detecting a transfer current value that contributes to transfer to the recording material, and the transfer power supply control means is configured so that a difference value between the bias current value and the transfer current value is constant. It is characterized by controlling the transfer power supply of the transfer means, and by controlling the difference current between the detected bias current value and the transfer current value, it is possible to realize constant transfer current control in consideration of transfer leakage current. Become.

  (5) The apparatus further comprises bias power supply control means for controlling the bias power supply of the fixing means based on the bias current value detected by the current detection means, and controls the bias voltage by detecting the bias current value. Accordingly, it is possible to realize appropriate transfer voltage supply and transfer control in consideration of transfer leakage current, as compared with conventional control of only transfer voltage or transfer current.

  As described above, according to the present invention, in a system including a heating member for fixing a toner image on a recording material or a means for applying a bias voltage to at least one of the pressing members, the heating member or the pressing member By providing the current detection means in the conduction path connecting the bias voltage circuit to the bias voltage circuit, it becomes possible to detect the leakage current to the bias voltage circuit, and by providing feedback of the information, appropriate transfer control is realized, and the moisture absorbent paper Thus, there is an effect that it is possible to maintain the image quality even in a situation where a leakage current occurs, such as when using.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 8 is a schematic configuration diagram of an electrophotographic laser beam printer (hereinafter referred to as LBP) which is an example of an image forming apparatus to which the fixing bias output circuit of the present embodiment is applied.

  In FIG. 8, reference numeral 1 denotes an organic photosensitive drum (hereinafter abbreviated as a photosensitive drum) as an image carrier having an organic photosensitive layer formed on the surface thereof, and is driven to rotate in the arrow direction X. 2 is a charging roller for uniformly charging the surface of the photosensitive drum 1 in a negative polarity, 3 is a laser scanner unit for performing laser exposure with intensity modulation according to image data, and 4 is a negative polarity one-component toner. Is a developing device that visualizes an electrostatic latent image, and performs so-called reversal development that develops the exposed portion. 5 is a transfer roller for transferring the toner image onto the recording material P, 6 is a charge eliminating needle for separating the recording material from the photosensitive drum 1, and 7 is for cleaning the toner remaining on the photosensitive drum 1 after the transfer process. It is a cleaner.

  The recording material P to which the toner image has been transferred is sent through a conveyance guide 8 to a fixing device including a heater unit 10, a pressure roller 11, a fixing inlet guide 9, a paper discharge guide 12, a paper discharge roller 13, and the like. The toner image is heated and fixed by being nipped and conveyed by the heater unit 10 and the pressure roller 11.

  In the present embodiment, the paper discharge roller 13 is made of conductive rubber, and the cored bar 13a is grounded. Therefore, when a fixing bias is applied to the fixing film, which will be described later, and the recording material P is nipped and conveyed by both the fixing film, the pressure roller 11 and the paper discharge roller 13, the bias power is supplied to the ground via the recording material P. An energization path Y is formed.

  Reference numeral 90 denotes a control unit including a CPU and a memory for controlling the operation of the LBP according to the present embodiment, and includes a top sensor 18 for performing communication control with an external device and detecting the front and rear end positions of the recording material, a paper discharge sensor 19, and the like. Based on the output of the motor, the energization control to the motor, laser, high voltage and heater is performed.

  In the present embodiment, a DC bias output from a primary charging high voltage output circuit (bias power supply) 20 is induced to the surface of the fixing film via a discharge resistor 26.

  In the fixing device, heat fixing is performed by applying an AC voltage from the commercial power source 213 to the resistance heating element on the heater 212. At this time, the application timing and application time are controlled by turning ON / OFF the switch element 302 by the control unit 90. The glass coating the heater 212 is electrically regarded as a capacitor, and the capacitance value in this embodiment is about several hundred pF. Accordingly, the AC voltage of the commercial power source 213 is transmitted from the resistance heating element through the coating glass to the fixing nip portion where the heater and the pressure roller sandwich the recording material.

(Configuration example of main part of fixing device)
FIG. 9 is a diagram illustrating a main part of the fixing device of the present embodiment.

  Reference numeral 212 denotes a ceramic heater in which a resistance heating element made of a silver alloy is printed on an alumina substrate, a glass coating is applied to the resistance heating element surface, and a thermistor 155, an electrode (not shown), and the like are arranged. 130 is a film guide / heater holder made of a heat-resistant resin such as a liquid crystal polymer, and 100 is a cylindrical base film surface having a thickness of 30 to 80 μm and an inner diameter of φ24 mm in which a heat conductive filler is dispersed in a polyimide resin. A primer layer with a carbon dispersion of 1 × 10E5 Ω · cm or less and a thickness of 2 to 10 μm is formed, and a resistance imparting a conductivity-imparting substance to a fluororesin is further formed thereon with a resistance of 1 × 10E7 Ω · cm The fixing film has a three-layer structure in which a release layer having a thickness of 1 to 10E13 Ω · cm and a thickness of 5 to 20 μm is formed. A reinforcing sheet metal 170 prevents the heater unit (heating member) 10 including the heater 150, the film 100, the film guide 130, and the like from causing unnecessary deformation due to pressure contact with the pressure roller (pressure member) 11. Is a discharge resistor that connects the high-voltage bias power supply 20 and the film 100.

('Tail image' phenomenon and countermeasures)
A toner scattering phenomenon called “tail image” will be described with reference to FIG.

  In the figure, the temperature of the fixing nip N formed by the pressure contact between the heater unit 10 and the pressure roller 11 is controlled to a temperature of about 150 ° C. to 200 ° C., and the moisture contained in the recording material P during the sheet passing. Always evaporate and vapor 60 is generated. Due to the vapor pressure, a part T of the unfixed toner image on the upstream side from the fixing nip portion N is blown off to the downstream side in the conveyance direction of the recording material, whereby the trailing image is generated.

  The fixing bias applied by the bias power source 20 via the discharge resistor 26 is applied to improve an image defect called “tailing”, and an outline of the operation of the fixing bias will be described below. To do.

  FIG. 11 is an example of an equivalent circuit when the recording material P onto which the toner image is transferred enters the fixing nip portion N when a DC bias having the same polarity as the toner is applied to the surface of the fixing film. Note that the same reference numerals as those in FIGS. 8 to 10 denote the same functional components.

  Reference numeral 102 denotes a conductive primer layer of the fixing film 100 described with reference to FIG. 9, a DC bias of −600 V is applied from the bias power source 20, and reference numeral 103 denotes a release layer described with reference to FIG. The bias is applied to the conductive primer layer 102 by bringing a power supply member such as a conductive brush or a conductive rubber ring (not shown) into contact with the conductive primer layer 102.

  Rd is a resistance from the bias power source 20 to the discharge resistor 26, Re represents a contact resistance between the power supply member and the conductive primer layer, and a resistance to the vicinity of the fixing nip N of the conductive primer layer 102, Rf Represents the resistance of the release layer. In the vicinity Pn of the fixing nip portion N (region between the release layer and the pressure roller), the recording material P such as paper is heated and water vapor is generated. Compared with other resistors connected in series, it is negligibly small, and can be regarded as equipotential in the Pn region. Since the moisture content of the paper after passing through the fixing nip portion N decreases and the temperature increases, the resistance value cannot be ignored, and the resistance to the paper discharge roller 13 that is a ground electrode is represented by Rg. Further, the contact resistance of the paper discharge roller 13 as the ground electrode with the recording material P and the resistance to the ground E are represented by Rh.

  In FIG. 11, −600 V is applied from the bias power supply 20, and the surface potential that appears on the surface of the fixing film 100 from −400 to −550 V due to the voltage drop due to the resistor Rd and the discharge resistor 26. When a current I flows from the conductive primer layer 102 of the fixing film 100 through the release layer 103, the recording material P, and the paper discharge roller 13 which is a ground electrode, between the conductive primer layer 102 and the equipotential portion Pn of the recording material P. An electric field Ef is generated. Accordingly, since the toner has a negative charge, the restraining force Ft acts on the recording material P, and particularly in the vicinity of the fixing nip N, the toner is strongly restrained by the recording material P, and the tailing, offset, scattering, etc. Image defects are greatly improved. When the voltage value of the bias power source 20 is constant, the strength of the electric field Ef increases as the resistance value of the discharge resistor 26 decreases, improving the improvement effect.

  However, when the resistance value of the discharge resistor 26 is reduced, when the recording material P is gripped by both the transfer portion and the fixing portion, the transfer current transmitted through the recording material P causes the fixing film 100 and the discharge resistor 26 to pass. Since it tends to flow out through, a transfer voltage (DC voltage) at a transfer nip portion (Nt in FIG. 1 described later) is lowered, resulting in problems such as a decrease in density and whiteout. Therefore, the resistance value of the discharge resistor 26 is limited by these conditions.

<First Configuration Example of Image Forming Apparatus of Present Embodiment>
FIG. 1 is a diagram showing an outline of the fixing bias output circuit of the present embodiment and its discharge resistance. In the present embodiment, the bias power source 20 is branched from the primary charging output circuit.

  In FIG. 1, the discharge resistor 26 includes two resistors 207 and 208, and a bias is applied to the fixing film through these resistors. The bias power source 20 is connected to the commercial power source 213 through the discharge resistors 207 and 208, the fixing film 100, and the heater 212. Therefore, in order to satisfy safety standards (IEC 60950 1999 etc.), it is necessary to provide reinforced insulation in these paths. In the present embodiment, the voltage value applied to the fixing film is about −600 V, and the maximum peak value of the commercial power supply is 240 × √2 = 340 V. Therefore, the maximum operating voltage is 940V. IEC 60950 requires basic insulation and additional insulation with a dielectric breakdown voltage of 2343 V for an operating voltage of 950 V.

  In this embodiment, resistors having a withstand voltage of 2343 V or more are used for 207 and 208. According to IEC 60950: 1999 “2.2.8.2”, in this embodiment, two resistors having a withstand voltage of 2343 V or more per resistor are connected in series to form double insulation of basic insulation and additional insulation. You can do that. Further, the resistance values of 207 and 208 need to be the same nominal resistance value according to the definition of the same term. In this embodiment, the resistance values of 207 and 208 are each 20 MΩ.

Here, regarding the resistance value of the recording material P, when recycled paper is used, the volume resistivity may decrease to about 2 × 10 ⁸ Ω · cm under high humidity. When converted to A4 size paper (length 297 × width 210 mm) having a thickness of 0.1 mm, the resistance value is approximately 300 MΩ. In this embodiment, since the distance between the fixing nip N and the transfer nip Nt is 120 mm, the resistance value therebetween is approximately 120 MΩ. Compared to this, the resistance value is at least two orders of magnitude greater under non-humidity.

  FIG. 2 shows each resistance value in a humid environment existing between the transfer power supply 300 (+1 kVdc) and the bias circuit 20 (−600 Vdc). FIG. 2 is based on an example of constant voltage control for controlling the transfer voltage to be constant.

  In the figure, R207 and R208 are the resistance values of the discharge resistors 207 and 208, Rt is the total value of the resistance value of the transfer roller 5 and the output impedance of the transfer power supply 300, and Rp is the length between the transfer nip Nt and the fixing nip N. The resistance value of the recording material P is shown. Nt and N indicate positions on the equivalent circuit corresponding to the transfer nip and the fixing nip, respectively.

  2A is an example when the recording material P does not absorb moisture, and FIG. 2B is an example when the recording material P absorbs moisture. From this figure, it can be seen that the transfer voltage on the transfer nip Nt is lower for the moisture absorbent paper than when the moisture absorbent paper is a non-absorbent paper. When the voltage on the transfer nip Nt decreases as shown in FIG. 2B, a current of about 5 μA flows through the path of the discharge resistors 207 and 208. A current may flow up to several tens of μA due to changes in the transfer voltage and other conditions.

  In the present embodiment, the discharge resistor 208 is used as a current detection resistor, and the detection voltage is detected by the control unit 90, thereby making it possible to detect a leak amount of a bias current, that is, a transfer current. In the present embodiment, the detection resistance value is 20 MΩ, and a detection voltage of 100 V is obtained when a bias current of 5 μA flows, so that sufficient resolution can be realized. In this embodiment, by providing a current detection circuit in the actual leakage path, the actual leakage current can be measured, and the timing at which the current leakage path is formed by the recording material is detected and synchronized with the timing. It is important to be able to control.

<Second Configuration Example of Image Forming Apparatus of Present Embodiment>
In the first configuration example, the discharge resistor 208 is also used as a current detection resistor. However, in the second configuration example, a configuration in which a current detection resistor 209 is provided separately from the discharge resistors 207 and 208 is shown in FIG.

  According to the second configuration example, the detection resistance is placed closer to the bias circuit 20 side than the discharge resistances 207 and 208 when viewed from the heater 212 side (i.e., the AC primary side), thereby providing basic insulation and additional insulation conditions according to safety standards. Therefore, the detection circuit can be configured at a low cost.

  The transfer voltage or bias voltage can be variably controlled based on the bias current value obtained from the current detection circuit as described above. For example, in order to prevent the transfer voltage at the transfer nip Nt in FIG. 2B from decreasing with an increase in the bias current value, an example in which the transfer voltage or the bias voltage is increased, or the bias current exceeds the set threshold value. Examples of such a case include switching the transfer control mode (for example, keeping the transfer voltage constant at a high voltage).

<Configuration and Operation Example of Control Unit 90 of this Embodiment>
FIG. 4 is a block diagram illustrating a configuration example of the control unit 90 of FIG.

  In FIG. 4, 91 is a CPU for calculation / control, 92 is a ROM and / or RAM for storing control programs and data (parameters, etc.) executed by the CPU 91, and 92 and 93 are external input interfaces. In this example, the voltage value from the resistors 208 and 209 which are current detection circuits is input. An output interface 94 outputs various voltage control signals determined by the control unit 90 for transfer voltage control, fixing bias voltage control, and fixing heater power source (timing) control.

  The storage unit 92 includes a voltage control program 92a as a program of the first control example described below of the control unit 90, a transfer current control program 92b as a program of the second control example, and both ends of the current detection resistor acquired via the input interface 93. An area 92c for storing a bias current value calculated from the voltage value of the current, and an area 92d for storing a bias current / control voltage table for determining a transfer voltage or bias voltage to be controlled from the bias current value in the first control example. ing. Instead of storing as a bias current / control voltage table, the control target transfer voltage or bias voltage may be calculated from the bias current value.

  In the example of FIG. 4, for example, when the bias current is A00 or less, the transfer voltage is 1 kV and the bias voltage is a specified value of −600 V, and the bias voltage is between A00 and A00 and A0m. Although it does not change, the transfer voltage is increased, and when the bias current exceeds A0m from A01 to A1n, the bias voltage is increased without changing the transfer voltage (decreasing the negative value), and the bias current exceeds A1n and A20 A bias current / control voltage table is shown in the figure in which it is determined that a failure has occurred and both the transfer voltage and the bias voltage are turned off.

(First control example of the control unit 90)
FIG. 5 is a flowchart illustrating an example of an operation procedure of a voltage control program 92a that controls a transfer voltage and a bias voltage based on a bias current, which is a first control example.

  First, in step S51, the bias current value is detected from the voltage value from the current detection resistor. In step S52, the transfer voltage corresponding to the bias current value and the control target value of the bias voltage are calculated. Such calculation may be determined or calculated from the bias current / control voltage table 92d as described above. In step S53, the respective power supply voltages are set to the transfer voltage and the bias voltage calculated in step S52. In step S54, after waiting for a predetermined time, the process returns to step S51 to perform detection and control again. The predetermined time is a time interval at which an environmental change (in particular, a change in humidity) affects the recording material. Alternatively, the detection and control may be performed before the start of one image forming job.

  As described above, according to the first control example, by detecting the bias current value and controlling the transfer voltage and the bias voltage, the transfer leakage current can be reduced as compared with the conventional control of the transfer voltage or the transfer current alone. Considering this, it is possible to realize appropriate transfer voltage supply and transfer control.

(Second control example of the control unit 90)
In the first control example, the configuration in which the transfer voltage and the transfer current are controlled by the detected bias current value has been described. In the second control example, the detected bias current value and the transfer current value are used as the basis. Next, a configuration for performing control will be described. In this example, as an example, description will be made based on an example of constant current control in which the transfer current is controlled to be constant.

  FIG. 6 shows an outline of a path through which a transfer current flows.

  Id in FIG. 6 indicates a current value (charge amount) consumed for transferring the toner on the photosensitive drum 1 to the recording material, and Rdt indicates a resistance value of the path. It is a current value supplied from the transfer power supply 300, and it is ideal that It and Id are equal to each other. However, in the configuration in which the fixing bias is applied as described above, as indicated by Ib. Leakage current is generated.

  In the conventional transfer constant current control, control is performed so that only the transfer current It is detected and kept at a constant value. However, since there is a leak current such as Ib, the transfer current value and transfer control design are controlled. It was very difficult. In the present embodiment, the current value of Id that actually contributes to the transfer can be easily grasped by measuring the leakage current Ib to obtain the differential current (It−Ib). By controlling the transfer current value so that Id is constant, even when a leak current such as Ib occurs, an appropriate transfer current can be supplied to prevent fluctuations in image density. .

  FIG. 7 is a flowchart illustrating an example of an operation procedure of the transfer current control program 92b that controls the transfer current based on the bias current value and the transfer current value, which is the second control example. As shown in FIG. 7, in the actual operation flow, It is controlled to be (Id + Ib).

  First, in step S71, the bias current value Ib is detected from the voltage value from the current detection resistor. Next, in step S72, control is performed so that Id (= It−Ib) becomes a constant value. Specifically, (Id + Ib) is calculated in step S72a, and the transfer current source is controlled so that It becomes (Id + Ib) in step S72b. In step S73, after waiting for a predetermined time, the process returns to step S71 to perform detection and control again. The predetermined time is also a time interval at which an environmental change (in particular, a change in humidity) affects the recording material, as in the first control example. Alternatively, the detection and control may be performed before the start of one image forming job.

  As described above, according to the second control example, by controlling the difference current between the detected bias current value and the transfer current value, it is possible to realize the transfer constant current control in consideration of the transfer leak current. .

  The first control example and the second control example may be performed independently or in combination. In the above embodiment, the timing at which the current leakage path is formed is detected and the details of the control synchronized with the timing are not shown. However, the change in the bias current value is detected and synchronized with the timing. The processing procedure for controlling the power supply voltage and current can be performed by performing an interrupt process using a change in the bias current value as an event input.

  Further, as a storage medium for supplying the program code of this embodiment, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD, a DVD, a magnetic tape, a nonvolatile memory card, a ROM, or the like is used. it can.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  Furthermore, in an image input device such as a camera or scanner, an image output device such as a printer, or a device in which these are combined or connected, a CPU or the like provided in both or any of the devices performs part or all of the actual processing. Needless to say, the process includes the case where the functions of the above-described embodiments are realized.

1 is a diagram illustrating a first configuration example of an image forming apparatus according to an exemplary embodiment. FIG. 6 is an equivalent circuit diagram for explaining a decrease in transfer voltage when moisture absorbent paper is used. It is a figure which shows the 2nd structural example of the image forming apparatus of this embodiment. FIG. 3 is a diagram illustrating a configuration example of a control unit of the image forming apparatus according to the present exemplary embodiment. It is a flowchart which shows the operation | movement procedure of the 1st control example of the control part of this embodiment. It is an equivalent circuit diagram for explaining a path through which a transfer current flows. It is a flowchart which shows the operation | movement procedure of the 2nd control example of the control part of this embodiment. 1 is a diagram illustrating an overall configuration of an image forming apparatus. FIG. 2 is a diagram illustrating a configuration of a fixing device applied to the image forming apparatus. It is a figure for demonstrating the "tailing" which is the conventional subject. It is a conceptual diagram of the general countermeasure with respect to the "tailing" which is the conventional subject.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic photosensitive drum 2 Charging member 10 Heater unit 11 Pressure roller 13 Paper discharge roller 33 Static elimination brush 20 High voltage power supply for primary charging 26 Discharge resistance 50 Fixing roller 90 Controller 100 Fixing film 102 Primer layer of fixing film 103 Fixing film Release layer 130 Film guide 155 Thermistor 170 Reinforcing sheet metal 207, 208 Discharge resistance 209 Detection resistance 212 Heater 213 Commercial power supply 300 Transfer power supply 301 Resistance

Claims (10)

Charging means for charging the image carrier;
Exposure means for forming an electrostatic latent image on the image carrier;
Developing means for developing the electrostatic latent image as a toner image;
Transfer means for transferring the toner image onto a recording material;
An image forming apparatus comprising: a fixing unit configured to fix the toner image on the recording material by sandwiching and conveying the toner image on the recording material between at least a heating member and a pressure member having an elastic layer.
The fixing means;
Bias voltage generating means for applying a bias voltage to at least one surface of the heating member or the pressure member;
Conductive means for connecting the surface of the heating member or pressure member and the bias voltage generating means;
An image forming apparatus comprising: a current detection unit for measuring a bias current value flowing through the conductive unit.   2. The current detection means is provided between the insulation resistance and a bias voltage generation means after an insulation resistance is arranged on the surface side of the heating member or the pressure member. Image forming apparatus.   The image forming apparatus according to claim 1, further comprising a transfer power source control unit that controls a transfer power source of the transfer unit according to a bias current value detected by the current detection unit. A detection means for detecting a transfer current value contributing to the transfer to the recording material;
The image forming apparatus according to claim 1, wherein the transfer power source control unit controls a transfer power source of the transfer unit so that a difference value between the bias current value and the transfer current value is constant. .   5. The image forming apparatus according to claim 1, further comprising a bias power source control unit that controls a bias power source of the fixing unit based on a bias current value detected by the current detection unit. Charging means for charging the image carrier;
Exposure means for forming an electrostatic latent image on the image carrier;
Developing means for developing the electrostatic latent image as a toner image;
Transfer means for transferring the toner image onto a recording material;
A power supply control method in an image forming apparatus, comprising: a fixing unit that fixes a toner image on the recording material by nipping and conveying the toner image on the recording material between at least a heating member and a pressure member having an elastic layer. There,
Bias for measuring a bias current value flowing through a conductive means for connecting a surface of the heating member or the pressure member and a bias voltage generating means for applying a bias voltage to at least one surface of the heating member or the pressure member A current detection step;
And a transfer power source control step for controlling a transfer power source of the transfer unit based on the measured bias current value. A transfer current detection step of detecting a transfer current value contributing to transfer to the recording material;
7. The power supply control method according to claim 6, wherein in the transfer power supply control step, a transfer power supply of the transfer unit is controlled so that a difference value between the bias current value and the transfer current value is constant. .   The power supply control method according to claim 6 or 7, further comprising a bias power supply control step of controlling a bias power supply of the fixing unit based on the measured bias current value. Charging means for charging the image carrier;
Exposure means for forming an electrostatic latent image on the image carrier;
Developing means for developing the electrostatic latent image as a toner image;
Transfer means for transferring the toner image onto a recording material;
A power supply control method for an image forming apparatus, comprising: a fixing unit that fixes a toner image on the recording material by holding and conveying the toner image on the recording material between at least a heating member and a pressure member having an elastic layer. A power control program to be realized,
Bias for measuring a bias current value flowing through a conductive means for connecting a surface of the heating member or pressure member and a bias voltage generating means for applying a bias voltage to at least one surface of the heating member or pressure member A current detection step;
Based on the measured bias current value, a transfer power source control step for controlling the transfer power source of the transfer unit and / or for controlling the bias power source of the fixing unit based on the measured bias current value. A power supply control program comprising: a bias power supply control step to perform.   A storage medium for storing the power supply control program according to claim 9 in a computer-readable manner.

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