JP2004163913A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an occurrence of a slip between a pressure member and a recording material which conveys a recording medium while pressing the medium against a heat member. <P>SOLUTION: A temperature decrease period for decreasing the temperature of a pressure roller 24 is provided between a fixing operation for paper P on which a toner image corresponding to the previous image information signal is transferred and a fixing operation for paper P on which a toner image corresponding to the subsequent image signal is transferred. A specific temperature decrease period is set based upon environment information outputted by a transfer voltage control part 9. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art In an image forming apparatus (image recording apparatus) using an image forming process such as an electrophotographic method or an electrostatic recording method, an electrostatic latent image is formed on a photosensitive drum or the like as an image carrier, and the latent image is developed by a developer. The toner image is transferred to a recording material such as paper, and then the recording material on which the toner image has been transferred is fixed to a fixing roller and a pressure roller provided in a fixing device. Then, the toner image is heated and fixed as a permanent image on the recording material by passing through the nip portion formed by (1) and (2).

  FIG. 13 is a schematic side view of a main part showing a typical example of such an image forming apparatus. The surface of a photoreceptor 1 (hereinafter referred to as a “photosensitive drum”) extending in a direction perpendicular to the paper and rotating in an arrow X direction is uniformly charged by a charging roller 2 connected to a high-voltage power supply 7, and a laser scanner 3 is provided. As a result, a laser beam L modulated by an image signal is applied to the charged surface to form an electrostatic latent image. The toner 5 is supplied from the developing device 4 to the latent image to form a toner image and arrives at the transfer nip portion T.

  The transfer portion T is composed of a nip portion between the photosensitive drum 1 and a conductive transfer roller 6 in contact with the photosensitive drum 1, and the recording material P is supplied at the timing when the toner image portion on the photosensitive drum 1 reaches the transfer portion T. And passes through the nip. At this time, a transfer bias is applied to the transfer roller 6 by the power supply 8, and the toner image on the photosensitive drum 1 is transferred to the recording material P. Thereafter, the recording material P carrying the toner image leaves the transfer portion T and is conveyed to a fixing device (not shown).

  In recent years, a film heating type fixing device using a fixing method that minimizes power consumption without supplying power to the fixing device particularly during standby has been proposed (for example, see Patent Documents 1 to 4).

  The fixing device includes a heater (heating body), a heat-resistant film (fixing film) that slides with the heater, and a pressure member that forms a fixing nip by pressing the heater through the film. The recording material on which the unfixed image is formed is sandwiched and conveyed between the film and the pressing member in the fixing nip portion, and the unfixed image is recorded by the heat from the heater applied through the film and the pressing force of the fixing nip portion. This is a device for fixing a permanent image on a material.

  Such a film heating type fixing device can use a linear heating element having a low heat capacity as a heater and a thin film having a low heat capacity as a film, so that it is possible to save power and shorten a wait time (quick start). It is.

  Further, in this type of film heating type fixing device, as a driving method of a fixing film, a pressing roller as a pressing member is applied while applying tension using a dedicated transport roller and a driven roller for transporting the film. There is a system in which the fixing film is transported between them, and a tensionless system in which the cylindrical fixing film is driven by the conveying force of the pressing roller by rotating and driving a pressing roller as a pressing member. The former has the advantage that the transportability of the fixing film can be improved, and the latter has the advantage that the apparatus configuration can be simplified and a low-cost apparatus can be realized.

  Further, with the recent development of the computer industry, the demand for printers has been increasing, and the printers have come to be used all over the world. As a result, the type of paper used is also rich in various types such as thickness and surface properties, and at the same time, coupled with the speeding up of the image forming apparatus, from the viewpoint of shortening the printing time of the first sheet and securing the fixability of the first sheet, The instantaneous amount of heat applied from the heater to the recording material was gradually increased, and satisfactory fixing performance was obtained. Furthermore, in recent years, the demand for high image quality by users has been increasing, and a printer having excellent dot reproducibility and gradation has been announced. By further reducing the particle diameter of toner as a developer (developer), high image quality can be achieved. Has been planned.

  Regarding the transfer bias control of this type of image forming apparatus, an ATVC (Active Transfer Voltage Control) method has been previously proposed (for example, see Patent Document 5).

This method is a means for optimizing a transfer bias applied to the transfer roller 6 at the time of transfer, applying a desired constant current bias from the transfer roller 6 to the photosensitive drum 1 during the initial rotation of the image forming apparatus, and detecting a detection voltage at that time. The transfer bias is optimized by detecting the resistance value of the transfer roller from Vo and selecting a constant voltage bias according to the resistance value during transfer. In this case, the transfer voltage Vt is represented by the following equation (ATVC equation).
Vt = AVo + B (A and B are constants)
In the contact transfer method, the optimum voltage value to be applied to the leading end of the recording material changes depending on the resistance value of the transfer roller. In addition, the transfer roller has a large variation in resistance value, and the recording material characteristic changes drastically from a high humidity environment (H / H) to a low humidity environment (L / L). Taking advantage of this characteristic, it is possible to distinguish the H / H environment and the L / L environment from the resistance value of the transfer roller, and to prevent the transfer property of the transfer roller from being changed due to environmental changes.

Vt is calculated based on Vo obtained by the initial rotation in order to prevent development due to transfer current failure such as an explosion image at the leading end of the recording material.
JP-A-63-313182 JP-A-2-1577878 JP-A-4-44075 JP-A-4-204980 JP-A-2-264278

  The image forming apparatus that performs the operation described above has the following problems.

  The fixing device of the image forming apparatus performs temperature control using a heater, which is a heating element, to stably fix a toner image on a sheet. In detail, the control unit that controls the printer performs temperature control based on the resistance value of the thermistor whose resistance value changes according to the temperature of the heater, but the heater and the thermistor are provided inside the film, and the pressurization is performed. No rollers are provided.

  Therefore, even if the temperature of the heater is constant, the temperature detected by the thermistor does not always match the temperature of the pressure roller. For example, the temperature of the pressure roller changes depending on the size and thickness of the sheet, the heat absorbing property, and the interval between the conveyance of a plurality of sheets.

  The surface layer of the pressure roller is formed of a PFA tube or the like. When the temperature exceeds a certain temperature due to the properties of the material, the force for transporting the paper P (hereinafter referred to as the transport force) decreases, and There is a problem that a slip jam (hereinafter, referred to as slip) occurs between the sheet and the sheet.

  Here, slip refers to paper (recording) in which a toner image as an unfixed image is placed in a fixing nip portion in a fixing device of a type in which a pressure roller is driven by a motor and a film is driven by rotation of the pressure roller. When the material is conveyed, the paper present between the pressure roller and the film slides without following the rotation of the pressure roller.

Generally, as a condition of the paper P in which the slip is likely to occur, a paper having a water content of 8.0% or more when left in a high temperature and high humidity (H / H) environment and having a basis weight of 70 g / m ² or less can be given. .

  FIG. 4 is a graph showing the relationship between the surface temperature of the pressure roller and the conveyance force (gf) applied to the sheet by the pressure roller. As can be seen from FIG. 4, when the surface temperature of the pressure roller exceeds 125 ° C., the conveyance force applied to the sheet by the pressure roller sharply decreases.

  Here, the surface temperature of the pressure roller is the temperature at the moment when the leading edge of the sheet enters the fixing nip. When a paper with a high moisture content that has absorbed water under a high-temperature and high-humidity environment is passed through the pressure roller, the moisture retained by the paper evaporates, and a water vapor layer is formed between the paper and the pressure roller. It is considered that the conveyance force applied to the sheet by the pressure roller is reduced, and the slip easily occurs between the sheet and the pressure roller.

  The present invention has been made in view of such a problem, and conveys a recording material while applying pressure to a heating member even when an environment where an image forming apparatus is placed is a high-temperature and high-humidity environment. And an image forming apparatus capable of preventing the occurrence of a slip between the pressing member and the recording material.

  In order to achieve the above object, the present invention provides a charging unit for charging an image carrier to a predetermined potential, and an electrostatic latent image corresponding to an image information signal from an external device on the image carrier charged by the charging unit. Exposure means for exposing the image carrier to form, developing means for developing the electrostatic latent image on the image carrier with a developer to form a developer image, and recording the developer image on the image carrier Transfer means for applying a transfer voltage to a transfer member to transfer the developer image onto the recording material, a heating member for thermally fixing the developer image on the recording material on which the developer image has been transferred by the transfer means, and a recording material applied to the heating member. Fixing means having a pressing member for conveying while pressing, output means for outputting information about the environment where the image forming apparatus is placed, and a recording material on which a developer image corresponding to the previous image information signal is transferred And the developer image corresponding to the next image signal is transferred. Control means for providing a predetermined temperature reduction period for lowering the temperature of the pressure member between the fixing operation and the fixing operation on the recording material, wherein the control means outputs the predetermined temperature reduction period to the output unit. It is set based on information about

  Further, the present invention provides a charging unit for charging the image carrier to a predetermined potential, and an image forming unit for forming an electrostatic latent image on the image carrier charged by the charging unit in accordance with an image information signal from an external device. Exposure means for exposing the carrier, developing means for developing the electrostatic latent image on the image carrier with a developer to form a developer image, and transferring the developer image on the image carrier to a recording material A transfer unit that applies a transfer voltage to the transfer member, a heating member that thermally fixes the developer image on the recording material onto which the developer image has been transferred by the transfer unit, and a recording material that is conveyed while being pressed against the heating member. Fixing means having a pressure member, detecting means for detecting a transfer voltage applied to the transfer member so that a constant current flows through the transfer member, and recording on which a developer image corresponding to the previous image information signal has been transferred. The fixing operation for the material and the transfer of the developer image corresponding to the next image signal Control means for providing a predetermined temperature lowering period for lowering the temperature of the pressing member between the fixing operation and the fixing operation on the recording material, wherein the control means detects that the transfer voltage detected by the detecting means is lower than the predetermined voltage. The predetermined temperature lowering period in a certain case is made longer than the predetermined temperature lowering period when the transfer voltage is higher than the predetermined voltage.

  According to the present invention, between the fixing operation on the recording material on which the developer image corresponding to the previous image information signal has been transferred and the fixing operation on the recording material on which the developer image according to the next image signal has been transferred. A predetermined temperature reduction period for lowering the temperature of the pressure member is provided, and the predetermined temperature reduction period is set based on information about the environment output from the output unit. Even in a high-humidity environment, it is possible to prevent the occurrence of slip between the recording member and the pressing member for conveying the recording material while pressing the recording material against the heating member.

  Further, a pressing member is provided between the fixing operation on the recording material on which the developer image corresponding to the previous image information signal is transferred and the fixing operation on the recording material on which the developer image is transferred according to the next image signal. A predetermined temperature lowering period for lowering the temperature of the transfer member is provided, and a predetermined temperature lowering period when the transfer voltage applied to the transfer member is equal to or lower than the predetermined voltage so that a constant current flows through the transfer member is set to a predetermined temperature lowering period. Since it is longer than the predetermined temperature lowering period when the voltage is higher than the voltage, even if the environment in which the image forming apparatus is placed is a high-temperature and high-humidity environment, a process for pressing and conveying the recording material to the heating member is performed. It is possible to prevent a slip from occurring between the pressure member and the recording material.

(1st Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 2 is a schematic diagram showing a configuration of the electrophotographic laser beam printer 100 according to the first embodiment.

  In FIG. 2, reference numeral 101 denotes a printer control unit which controls each unit of the laser beam printer 100 to form an image on a sheet P.

  2, an image processing control unit 102 receives an image information signal to be printed from an external device such as a host computer, and converts the received image information signal into an image signal that can be formed by the laser beam printer 100. This is a process for conversion. The image processing control unit 102 transmits an image signal to the printer control unit 101 and transmits a print start instruction and the like.

  In FIG. 2, reference numeral 3 denotes a laser scanner, and a printer control unit 101 controls a laser beam L which the laser scanner 3 irradiates the photosensitive drum 1 based on an image information signal sent from a laser beam printer 100 from an external device such as a host computer. Modulate intensity.

  The surface of the photosensitive drum 1 on which the laser scanner 3 exposes the laser beam L is charged to a uniform potential by the charging roller 2, and the laser beam L irradiated on the photosensitive drum 1 forms an electrostatic latent image. It is formed.

  The electrostatic latent image is conveyed to the opposing portion between the developing device 4 and the photosensitive drum 1 by the rotation of the photosensitive drum 1 in the direction of the arrow, and the electrostatic latent image is sequentially developed by the developing device 4 with toner as a developer. Is done.

  Then, the printer control unit 101 transfers the toner image developed by the developing device 4 onto the sheet P serving as a recording material sent from the sheet feeding device 12 serving as a recording material supply unit to the transfer nip portion T. 6 to sequentially transfer.

The transfer roller 6 is formed by forming an elastic layer of an ion conductive NBR (nitrile butadiene rubber) on a 6 mm iron core metal, and has a diameter of 15 mm and a hardness of 45 ° (when 500 g of Asker-C is loaded). The resistance value was set to 8 × 10 ⁸ Ω by adjusting the composition of NBR. The ion conductive solid rubber has a remarkable characteristic that the resistance value changes according to the environment where the laser beam printer 100 is placed, and as a kind of environment sensor for detecting the environment where the laser beam printer 100 is placed. Can be used.

  Reference numeral 8 denotes a DC high voltage generator that is a transfer voltage application unit that generates a transfer voltage applied to the transfer roller 6, and 9 denotes a transfer voltage controller that controls the DC high voltage generator 8. The printer control unit 101 separates the sheet P on which the toner image has been transferred at the transfer portion T with the rotation of the photosensitive drum 1 and sends the sheet P to the fixing device 11.

  Next, the configuration of the fixing device 11 will be described.

  The fixing device 11 is a so-called tensionless type of a film heating method and a pressure rotating body driving method, and FIG.

  The fixing device 11 includes a film inner guide member 21 having heat resistance and rigidity, and an energization fixed to a lower surface of the film inner surface guide member 21 by being fitted into a concave groove formed along the length of the film inner surface guide member 21. And a heater 22 that generates heat.

  As the heater 22, for example, a ceramic heater or the like is used.

  A cylindrical fixing film 23 made of a heat-resistant resin and having an outer peripheral length of about 57 mm is loosely fitted into the film inner surface guide member 21 into which the heater 22 is fitted. The fixing film 23 is made of a heat-resistant resin such as polyimide. The inner peripheral length of the fixing film 23 is larger than the outer peripheral length of the film inner surface guide member 21 including the heater 22 by 3 mm. It is loosely fitted.

  Further, the fixing device 11 has a pressure roller 24.

  Reference numeral 24 denotes a pressing roller (pressing roller, drive roller) as a pressing rotating body, and a film 23 is sandwiched between the pressing roller 24 and a film inner surface guide member 21 including a heater 22. The pressure roller 24 includes a rotating shaft composed of a metal core 25 and a heat-resistant rubber such as silicone rubber or fluorine rubber formed concentrically and integrally on the metal core, or an elastic layer formed by foaming silicone rubber or the like. Body. The pressure roller 24 is disposed such that both ends of the core bar 25 are rotatably supported between front and rear side plates of the apparatus chassis via a bearing member. The pressure roller 24 and the film inner surface guide member 21 are fixed so as to be pressed against each other, and form a fixing nip portion N.

  The pressure roller 24 is driven to rotate at a predetermined peripheral speed by the rotation control unit 10 controlled by the printer control unit 101.

  A rotational force acts on the cylindrical film 23 due to the frictional contact between the outer surface of the pressure roller 24 and the film 23 due to the rotation of the pressure roller 24 and the film 23 at the fixing nip portion N. While the inner surface side is in close contact with the downward surface of the heater 22 and slides, the outer periphery of the film inner surface guide member 31 is driven to rotate. The rotation control means 10 has a motor 26 for driving the pressure roller 14 to rotate, and a CPU 27 for controlling the rotation of the motor 26.

  The printer control unit 101 drives the pressure roller 24 to rotate, and accordingly, the cylindrical film 23 is driven to rotate.

  Further, the printer control unit 101 energizes the heater 22 and, between the film 23 and the pressure roller 24 of the fixing nip portion N, in a state where the temperature of the heater 22 rises to a predetermined temperature and the temperature is controlled. A recording material P carrying an unfixed toner image t is introduced.

  Then, the printer control unit 101 causes the toner image bearing surface side of the recording material P to be in close contact with the outer surface of the film 23 in the fixing nip portion N, and causes the fixing nip portion N to be conveyed together with the film 23. In this nipping and conveying process, the heat of the heater 22 is applied to the sheet P via the film 23, and the unfixed toner image t on the sheet P is heated and pressed onto the sheet P to be fused and fixed. The sheet P that has passed through the fixing nip N is separated from the film 23 by a curvature.

  Next, an image forming operation by the laser beam printer 100 will be described.

(Standby operation)
The printer control unit 101 drives a main motor (not shown) to rotate the photosensitive drum 1 when the power of the laser beam printer 100 is turned on.
Then, the printer control unit 101 applies a predetermined high voltage to the charging roller 2 to stabilize the surface potential of the photosensitive drum 1 to a predetermined potential so that the laser beam printer 100 can form an image on the paper P. (Hereinafter, referred to as a standby operation). This standby operation brings the laser beam printer 100 into a predetermined preparation state.

(Initial rotation operation)
Next, in response to an image information signal being sent from an external device such as a host computer, an operation for shifting the laser beam printer 100 from the ready state to a state in which an image is formed on the paper P is executed ( Initial rotation operation). When the image information signal is input from the image processing control unit 102 to the printer control unit 101 during the standby operation, the initial rotation operation is performed subsequently to the end of the standby operation.

  When there is no input of an image information signal, the printer control unit 101 stops the rotation of the photosensitive drum 1 by temporarily stopping the drive of the main motor after the end of the standby operation.

  Note that the printer control unit 101 sets the laser beam printer 100 in a predetermined standby state until an image information signal is input. Then, the printer control unit 101 executes an initial rotation operation, that is, a driving rotation including a pressure roller of the fixing device 11 in response to the input of the image information signal.

  Further, the printer control unit 101 starts power supply to the heater 22 of the fixing device 11 as an initial rotation operation.

  Here, when the image information signal from the external device such as the host computer does not include the specification information of the type of the sheet P, the printer control unit 101 controls the temperature of the heater of the fixing device 11 in the normal mode fixing temperature ( 165 ° C).

  The transfer high voltage controller 9 controls the transfer high voltage generator 8 so that a constant current of 4 μA flows through the transfer roller 6. Note that the laser beam printer 100 includes a transfer current detecting unit (not shown) that detects a transfer current value flowing through the transfer roller 6.

  Then, the printer control unit 101 performs so-called ATVC control for detecting the transfer voltage value Vo applied to the transfer roller 6 by the transfer high voltage generator 8 when the transfer current value becomes 4 μA. The transfer voltage value Vo is a voltage value according to the environment in which the laser beam printer 100 is placed. Based on the transfer voltage Vo, when the paper P passes through the transfer nip portion T, the transfer high voltage generator 8 The transfer application voltage Vt applied to the transfer roller 6 is calculated.

In the first embodiment, the transfer voltage Vt is calculated from the transfer voltage V0 using the following equation (1).
Vt = 2.2Vo + 0.8 (1)

(Image forming operation)
When the above-described initial rotation operation is completed, an image forming operation for forming a toner image on the photosensitive drum 1 is subsequently performed, and the transfer of the toner image formed on the photosensitive drum 1 to the paper P is performed. After that, the fixing device 11 performs a fixing process on the toner image on the sheet P, and the sheet P on which the toner image is formed is discharged.

  In a case where images of a plurality of pages are continuously formed on the paper P, the above-described operation is repeatedly performed by the set number of prints.

  When a plurality of pages of images are continuously formed on the sheet P, after the trailing edge of the sheet P passes through the transfer nip T, the leading edge of the next sheet P reaches the transfer nip T. Is a state in which the paper P does not exist in the transfer nip portion T (a so-called non-paper passing state).

(Post-rotation operation)
After the image forming operation for the last image related to the image information signal input from the external device is completed, a post-rotation operation, which is an end operation for shifting to a predetermined standby state, is performed again.

  Specifically, the printer control unit 101 continues to drive the main motor to rotate for a while after the fixing operation for the last page of the image information signal for one print job ends, and A predetermined high voltage is applied to stabilize the surface potential of the photosensitive drum 1 at a predetermined potential. At this time, since the image forming operation has already been completed, the printer control unit 101 turns off the heater of the fixing device 11 without supplying power.

  Note that the fixing operation is an operation in which power is supplied to the heater 22 when the sheet P passes through the fixing device 11 to thermally fix the toner image on the sheet P to the sheet P. The fixing operation shifts to the post-rotation operation in response to the rear end of the sheet P on the last page of the information signal passing through the fixing nip N.

  After performing the above post-rotation operation, the printer control unit 101 stops the driving of the main motor to stop the rotation driving of the photosensitive drum 1 until the next image information signal is input to the image processing control unit 102. A predetermined standby state is set.

  When an image is formed on only one sheet of paper P, the printer control unit 101 executes a post-rotation operation after the image forming operation on one sheet is completed, and sets the laser beam printer 100 in a ready state.

  Then, when an image information signal is input to the image processing control unit 102 in the standby state, the printer control unit 101 executes an initial rotation operation.

  The laser beam printer 100 that performs the operation described above has the following problems.

  As shown in FIG. 3, the fixing device 11 of the laser beam printer 100 performs temperature control by a heater 22 which is a heating element in order to stably fix the toner image on the paper P. More specifically, the printer control unit 101 performs temperature control based on the resistance value of the thermistor 29 whose resistance value changes according to the temperature of the heater 22. The heater 22 and the thermistor 29 are provided inside the film 23. Neither of the pressure rollers 24 is provided.

  Therefore, the temperature detected by the thermistor 29 does not always match the temperature of the pressure roller 24 even if the temperature of the heater 22 is constant. For example, the temperature of the pressure roller 24 changes depending on the size and thickness of the paper P, the heat absorbing property, and the transport interval of the plurality of papers P.

  The surface layer of the pressure roller 24 is formed of a PFA tube or the like. When the temperature exceeds a certain temperature due to the characteristics of the material, the force for conveying the paper P (hereinafter referred to as the conveyance force) decreases, There is a problem that a slip jam (hereinafter referred to as slip) occurs between the sheet 24 and the sheet P.

  Here, the slip means a toner image which is an unfixed image in the fixing nip portion N in the fixing device 11 in which the pressure roller 24 is driven by the motor 26 and the film 23 is driven by the rotation of the pressure roller 24. When a sheet of paper P (recording material) carrying is transported, the sheet P existing between the pressure roller 24 and the film 23 slides without following the rotation of the pressure roller 24. .

Generally, as a condition of the paper P in which slip is likely to occur, a paper P having a water content of 8.0% or more when left in a high-temperature and high-humidity (H / H) environment and having a basis weight of 70 g / m ² or less is given. Can be

  FIG. 4 is a graph showing the relationship between the surface temperature of the pressure roller 24 and the conveyance force (gf) applied to the sheet P by the pressure roller 24. As can be seen from FIG. 4, when the surface temperature of the pressure roller 24 exceeds 125 ° C., the conveyance force applied to the sheet P by the pressure roller 24 sharply decreases.

  Here, the surface temperature of the pressure roller 24 is the temperature at the moment when the leading end of the paper P enters the fixing nip N. When the paper P having a high water content, which has absorbed water under a high-temperature and high-humidity environment, is passed through the pressure roller 24, the moisture held by the paper P evaporates, and the paper P and the pressure roller 24 It is considered that a water vapor layer is formed, and the conveyance force applied to the sheet P by the pressure roller 24 is reduced, so that a slip easily occurs between the sheet P and the pressure roller 24.

  The resistance value of the transfer roller 24 is characterized in that a value in a high-temperature and high-humidity environment (H / H environment) is lower than a value in a low-temperature and low-humidity environment (L / L environment). The environment where the laser beam printer 100 is placed can be estimated from the transfer voltage value applied to the transfer roller 6.

  The operation of the first embodiment for solving the above-described slip problem will be described with reference to FIG.

  FIG. 1 is a flowchart illustrating a slip prevention control according to the first embodiment. FIG. 1 shows a case where the transfer voltage Vo during the preparatory operation for the ATVC control is detected and the environment where the laser beam printer 100 is placed is determined to be a high temperature and high humidity (H / H) environment. The control for cooling the pressure roller 24 in a short period of time by extending the time required for the rotation operation is shown. The details of the flowchart will be described below.

  In FIG. 1, when the image processing control unit 102 receives an image information signal from an external device such as a host computer, the printer control unit 101 executes a preparation operation (step S1). Here, when the image information signal from the external device such as the host computer does not include the specification information of the type of the sheet P, the printer control unit 101 controls the temperature control of the heater 22 of the fixing device 11 in the normal mode fixing temperature. (165 ° C.).

  Next, at the time when the charging of the photosensitive drum 1 by the charging roller 2 is completed, the printer control unit 101 controls the 4 μA for the ATVC control in a state where the photosensitive drum 1 and the transfer roller 6 are in contact with each other at the transfer nip T. Performs constant current control. The printer controller 101 detects the transfer voltage Vo applied to the transfer roller 6 by the transfer high voltage generator 8 via the transfer voltage controller 9 (step S2).

  Then, the printer control unit 101 holds the value of the transfer voltage Vo when the transfer current of 4 μA flows through the transfer roller 6 in the CPU 27 (step S3).

  Subsequently, the printer control unit 101 calculates the transfer voltage Vt using the equation (1) based on the transfer voltage Vo (step S4).

  Thereafter, the printer control unit 101 performs a constant voltage control for applying the transfer voltage Vt when the paper P passes through the transfer nip T (step S5).

  Then, in the next (Step S6), the printer control unit 101 determines whether or not the previously held transfer voltage Vo value is Vo> 0.5 kV. When Vo> 0.5 kV, the printer control unit 101 performs a normal post-rotation operation for 5 seconds as an end operation, and when Vo ≦ 0.5 kV, the time required for the post-rotation operation. Is extended for 3 seconds from normal to 8 seconds (step S7). When the post-rotation operation is being performed, the printer control unit 101 determines whether or not the image processing signal to be continuously printed is received even if the image processing control unit 102 receives the image information signal from an external device. Since image formation is not started, when Vo ≦ 0.5 kV, power is not supplied to the heater 22 for at least 8 seconds, so that the surface temperature of the pressure roller 24 does not become high enough to cause slip.

  Although the time required for the post-rotation operation is different between YES and NO in step S6, the printer control unit 101 turns off the heater 22 of the fixing device 11 in any case. .

  As described above, when the paper P is passed when the laser beam printer 100 is placed in a high-temperature and high-humidity environment (H / H environment), the printer control unit 101 performs the pressurization after the paper is passed. Since the surface temperature of the roller 24 can be cooled in a shorter period of time, even if the next image information signal is received immediately thereafter, the pressure roller 24 is not excessively heated. Thus, the phenomenon (slip) in which the conveyance force applied to the sheet P by the pressure roller 24 is reduced without causing the conveyance force applied to the sheet P by the pressure roller 24 to be reduced can be prevented.

  Here, using the LBP1210 manufactured by Canon Inc., which has a printing speed of 14 sheets / minute of A4 size paper, the change in the surface temperature of the pressure roller 24 and the confirmation of the slip during the intermittent printing in the first embodiment are checked. went. In the first embodiment, in order to compare the condition in which the surface temperature of the pressure roller 24 easily rises with the first embodiment, the following sheet 30 seconds after the post-rotation operation on the preceding sheet P is completed. The operation of starting image formation for P was performed for 100 sheets (○ in FIG. 5). Compared to the case where an image is formed intermittently (the paper P is passed at intervals of a predetermined time or more), when printing on 100 papers P continuously without performing the post-rotation operation As shown in FIG. 5, the pressure roller 24 does not warm up during the intermittent printing and generates less water vapor, so that no slip occurs.

  FIG. 6 shows the relationship between the number of prints and the temperature of the pressure roller 24 when image formation is started (cold start) with the pressure roller 24 not warmed. FIG. 7 shows the relationship between the number of prints and the temperature of the pressure roller 24 at the start (hot start).

  In FIGS. 6 and 7, after the printing on one sheet P is completed, the post-rotation operation is executed, and the printing on the next sheet P is started 30 seconds after the completion of the post-rotation operation. FIG.

  First, in FIG. 6 performed in a cold start, when the time required for the post-rotation operation is set to 5 seconds (図 in FIG. 6), a slip occurs on the twentieth sheet, and the pressure roller temperature at this time is about 135 ° C. Met. However, if the printer control unit 101 determines YES in step S6 of FIG. 1 and extends the time required for the post-rotation operation from the normal 5 seconds to 3 seconds to 8 seconds, the pressurizing operation is performed even when 100 sheets are passed. The roller temperature did not reach 130 ° C., and no slip occurred.

  Next, in FIG. 7 performed by hot start, when the time required for the post-rotation operation is 5 seconds (秒 in FIG. 6), the temperature of the pressure roller exceeds 135 ° C. in the second and third sheets. When the slip occurs at the point in time, the printer control unit 101 determines YES in step S6 of FIG. 1 and extends the time required for the post-rotation operation from the normal 5 seconds to 3 seconds to 8 seconds. The temperature did not reach 130 ° C. even when 100 sheets were passed, and no slip occurred.

  As described above, in the high-temperature and high-humidity environment (H / H environment), the next image information signal is input from the external device to the image processing control unit 102 immediately after the completion of the post-rotation operation. If the pressure roller 24 is sufficiently warmed up by the residual heat during printing, the time required for the post-rotation operation is extended to increase the temperature of the pressure roller 24 excessively. Thus, the occurrence of slip can be prevented by suppressing a decrease in the conveying force applied to the sheet P by the pressure roller 24. Here, in the first embodiment, the threshold value of Vo is set to 0.5 kV, and the extension time of the post-rotation operation is set to 3 seconds. It can be changed as appropriate depending on the performance of.

(Second embodiment)
Next, an operation in the second embodiment for solving the slip problem will be described with reference to FIG.

  FIG. 8 shows that the image forming operation is performed by detecting the resistance value of the transfer roller 24 by detecting the resistance value of the transfer roller 24 as in the first embodiment, and then the post-rotation operation is completed. When the next print signal arrives within 30 seconds after the start, the control to prevent the pressure roller 24 from excessively warming up by extending the waiting time until the image formation according to the next print signal is started. Is shown. The details of the flowchart will be described below.

  In FIG. 8, operations from step S1 to step S7 are the same as those in FIG. 1 of the first embodiment. In the second embodiment, when the value of Vo held in the CPU 27 is Vo ≦ 0.5 kV in step S3 and the next print signal comes within 30 seconds after the end of post-rotation (step S8) Normally, a waiting time of 3 seconds is provided for starting the supply of power to the heater 22 immediately after receiving the print signal, and then the process proceeds to the initial rotation operation of the next step S9. Step 9 and subsequent steps are the same as the previous print operation. If the intermittent time is 30 seconds or longer, the process directly proceeds to the initial rotation operation of the next step S9.

  In the case of continuous paper passing, there is no waiting time because the printing operation for the next image information signal has been started without performing the post-rotation operation. For this reason, the control for extending the standby time is not performed, but in the case of continuous paper feeding, the slippage does not occur because the pressure roller 24 does not excessively warm as described above.

  With this control, when intermittent paper feeding is continuously performed within 30 seconds in the H / H environment, the standby time can be extended to suppress a rapid rise in the surface temperature of the pressure roller 24. In addition, the conveyance force applied to the sheet P by the pressure roller 24 is not weakened, and the slip can be prevented.

  Here, using the same laser beam printer 100 as in the first embodiment, the time required for the post-rotation operation is set to 5 seconds, and the time required for the post-rotation operation is set to 8 seconds in the first embodiment. Also, when the standby time was set to 3 seconds in the second embodiment, a change in the pressure roller temperature and slippage during intermittent printing were confirmed. In the second embodiment, as a condition in which the temperature of the pressure roller 24 is apt to increase, 100 sheets of intermittent paper feeding are performed within 15 seconds. If the intermittent operation is performed within 15 seconds, the initial rotation operation for the next image information signal starts immediately after the rotation operation after the printing for the previous image information signal is completed. Since the cooling period inside the printer 100 is almost eliminated, the strictest conditions are set for the laser beam printer 100 used in the second embodiment.

  FIG. 9 shows the result of the measurement at the cold start, and FIG. 10 shows the result of the measurement at the hot start with the pressure roller 24 warmed.

  First, in FIG. 9 performed in the cold start, when the time required for the post-rotation operation is 5 seconds, slip occurs on the fifteenth sheet, and the surface temperature of the pressure roller 24 at this time was about 135 ° C. In the control of the first embodiment, although no slip occurred, the temperature became close to the threshold temperature of 135 ° C., which is the threshold temperature of the occurrence of slip, when 100 sheets were passed. However, in the control of the second embodiment, the stand-by time was set to 3 seconds, so that the surface temperature of the pressure roller 24 was kept lower than 130 ° C. even when 100 sheets were passed, and no slip occurred. .

  Next, in FIG. 10 performed by hot start, when the time required for the post-rotation operation was 5 seconds, the surface temperature of the pressure roller 24 exceeded 135 ° C. in the second sheet, and slip occurred at this point. In the control of the first embodiment, no slip occurred, but the temperature almost reached 135 ° C., which is the threshold temperature for the occurrence of slip, when 100 sheets were passed. However, in the control of the second embodiment, the stand-by time was set to 3 seconds, so that the surface temperature of the pressure roller 24 was kept lower than 130 ° C. even when 100 sheets were passed, and no slip occurred. .

  As described above, in the H / H environment, the intermittent printing (intermittent within 15 seconds in the second embodiment) in which the next image information signal comes immediately after the post-rotation operation is completed, When 24 is sufficiently warmed up by the residual heat at the time of printing, the time required for the post-rotation operation is extended, and the standby time until the next printing is extended, thereby preventing the temperature of the pressure roller 24 from excessively rising. The occurrence of slip can be prevented by suppressing a decrease in the conveying force. Here, in the second embodiment, the extension time of the standby is set to 3 seconds, but this can be changed as appropriate according to the performance of the laser beam printer 100 such as the printing speed and the temperature control temperature.

(Third embodiment)
FIG. 11 shows a flowchart of the slip prevention control in the third embodiment. In the third embodiment, after the transfer roller 6 determines that the environment is high-temperature and high-humidity (H / H), the image forming operation is performed, and then the next image information signal is generated within 30 seconds after the completion of the post-rotation operation. , The control to prevent the pressure roller 24 from excessively warming by starting the initial rotation operation and delaying only the timing of power supply to the heater 22 is shown. The details of the flowchart will be described below.

  In FIG. 11, steps other than step S9 are the same as in the second embodiment. If the value of the transfer voltage Vo held in the CPU 27 is Vo ≦ 0.5 kV, and if the next image information signal comes within 30 seconds after the completion of the post-rotation operation in step S9, the initial value is set as usual. The rotation operation is started, but at this time, the start of power supply to the heater 22 is delayed by 2 seconds. That is, only the rotation operation of the pressure roller 24 is performed without supplying power to the heater 22. As a result, the time required for the total preparation operation is extended by 2 seconds. Then, the process proceeds to the next step S10. Step 10 and subsequent steps are the same as the printing operation described in the second embodiment. If the intermittent time is 30 seconds or longer, in step S9, the initial rotation operation and the power supply to the heater 22 are simultaneously performed as in the second embodiment.

  With this control, when intermittent paper feeding is continuously performed within 30 seconds in the H / H environment, the start of power supply to the heater 22 is delayed to increase the idle rotation time of the pressure roller 24, thereby increasing the time. A rapid increase in the surface temperature of the pressure roller 24 can be suppressed. In addition, the conveyance force applied to the sheet P by the pressure roller 24 is not weakened, and the slip can be prevented. Further, the pressure roller 24 can be cooled in a shorter period of time by increasing the idle rotation time of the pressure roller 24 in addition to simply extending the standby time as in the second embodiment.

  Here, using the same laser beam printer 100 as in the first and second embodiments, the temperature change of the pressure roller 24 during the intermittent printing in the second and third embodiments is described. The slip was confirmed. In the third embodiment, as in the second embodiment, 100 sheets of intermittent paper are passed within 15 seconds, which is the condition under which the surface temperature of the pressure roller 24 is most likely to rise.

  The result of the measurement at the cold start and the result of the measurement at the hot start were almost the same as those in the second embodiment.

  As described above, in the H / H environment, the intermittent printing in which the next image information signal comes immediately after the completion of the post-rotation operation (intermittently within 15 seconds in the third embodiment) continues, and the pressure roller When the heater 24 is sufficiently warmed up by the residual heat at the time of printing, the time required for the post-rotation operation is extended, the start of power supply to the heater 22 is delayed, and the idle rotation time of the pressure roller 24 is increased to increase the pressure. It is possible to prevent the temperature of the roller 24 from excessively increasing, thereby suppressing a decrease in the conveying force applied to the sheet P by the pressure roller 24, thereby preventing the occurrence of a slip. In addition to extending the standby time, by increasing the idle rotation time of the pressure roller 24, the pressure roller 24 can be cooled in a shorter period of time.

  Here, in the third embodiment, power supply to the heater 22 is started two seconds after the start of the initial rotation operation. It can be changed appropriately depending on the performance.

(Fourth embodiment)
In the fourth embodiment, in addition to the control of the third embodiment, the next image is formed within 30 seconds after the image formation of all pages related to the previous image information signal is completed and the post-rotation operation is completed. The set temperature of the heater 22 is reduced by 10 ° C. only for the first intermittent print which is an information signal. More specifically, in step S8 of the third embodiment, when it is confirmed that the rotation is completed within 30 seconds after the completion of the post-rotation operation of the previous printing, the energization of the heater 22 is delayed by 12 seconds in the next step S9, Further, the temperature of the heater 22 is lowered by 10 ° C. than usual. Since the temperature control temperature in the normal mode in the fourth embodiment is 170 ° C., the temperature is controlled to 160 ° C. in this case. Further, when the continuous paper feeding is performed thereafter, the temperature is controlled not at -10 ° C but at the normal temperature, that is, at 170 ° C for the second and subsequent sheets.

  With this control, when intermittent paper feeding is continuously performed within 30 seconds in an H / H environment, the start of energization of the heater is delayed by 12 seconds, and the temperature control of the next first sheet is further reduced by 10 ° C. than usual. Therefore, not only can the rapid rise in the temperature of the pressure roller 24 be suppressed, but also the temperature at which the conveying force exerted on the sheet P by the pressure roller 24 can be maintained at all times. It is possible to always provide a stable image irrespective of the environment and the operation state of the laser beam printer 100.

  Here, using the same laser beam printer 100 as in the first to third embodiments, the temperature change and slip of the pressure roller 24 during the intermittent printing in the third and fourth embodiments are checked. Was. In the fourth embodiment, as in the second embodiment and the third embodiment, 100 sheets of intermittent paper passing within 15 seconds, which are the conditions under which the surface temperature of the pressure roller 24 is most likely to rise, are performed. .

  FIG. 12 shows the result of the measurement at the hot start. Also in the second embodiment, no slip has already occurred, and the surface temperature of the pressure roller 24 is kept around 130 ° C. However, in the fourth embodiment, a pressure roller having a conveyance force as shown in FIG. 4 is used. According to FIG. 4, the temperature of the pressure roller 24 at which the conveyance force is maximum is about 122 ° C. is there. Therefore, from the results of the fourth embodiment, it can be seen from FIG. 12 that the surface temperature of the pressure roller 24 during paper passing is always stable near the temperature at which the conveying force reaches the maximum value. As a result, not only does the slip not occur, but also it is possible to prevent the occurrence of disturbance in the parallelism and blurring of the image being conveyed by always maintaining a stable conveying force.

  As described above, in the H / H environment, the intermittent printing (intermittent within 30 seconds in the fourth embodiment) in which the next image information signal comes immediately after the completion of the post-rotation operation continues, and the pressure roller When is warmed up sufficiently by the residual heat during printing, the start of energization of the heater is delayed for 12 seconds, and the temperature control of the next first sheet is lowered by 10 ° C. from the normal, so that the surface temperature of the pressure roller 24 sharply rises. In addition to suppressing the temperature, the temperature at which the conveying force of the pressure roller 24 is maximized can be always maintained. It is possible to provide a stable image without disorder or blurring of the sex. In the fourth embodiment, the temperature control for lowering the first sheet is set to 10 ° C., but this can be changed as appropriate according to the performance of the laser beam printer 100 such as the printing speed and the temperature control temperature.

  In the first to fourth embodiments, the printer control unit 101 extends the time required for the post-rotation operation to lower the temperature of the pressure roller 24, and thereafter, the rotation of the heater 22 is performed in the rotation operation. Although the power supply was stopped, the same effect can be obtained by not only stopping the heater 22 but also making the power supplied to the heater 22 lower during the post-rotation operation than the power supplied to the heater 22 during the fixing operation. Can be obtained.

  In addition, the printer control unit 101 controls the heater 22 to be maintained at a predetermined temperature, and the same applies when the temperature maintained by the heater 22 during the post-rotation operation is lower than the temperature maintained by the heater 22 during the fixing operation. The effect of can be obtained.

Further, in the first to fourth embodiments, in order to determine the H / H environment (high temperature and high humidity environment), the transfer voltage applied by the transfer high voltage generator 8 to the transfer roller 24 so that the transfer current value becomes 4 μA. was used V _0, it may be determined whether or not the H / H environment (high-temperature and high-humidity environment) using another method.

  For example, the laser beam printer 100 is provided with a switch or the like that can be pressed when the user determines that the environment is an H / H environment, and the printer control unit 101 monitors an output signal indicating whether the switch is pressed or not. Alternatively, it may be determined whether or not the environment where the laser beam printer 100 is placed is a high-temperature and high-humidity environment.

  In the fixing device 11 according to the first to fourth embodiments, the fixing film 23 is not limited to the heat-resistant resin, and may be formed of a thin metal (metal sleeve) having flexibility.

  In the fixing device 11 according to the first to fourth embodiments, the heater 22 is not limited to a ceramic heater, but may be, for example, an electromagnetic induction heating member.

  Further, the heater 22 does not necessarily have to be located at the fixing nip portion. The fixing film 23 may be configured to be externally heated.

  Further, the fixing film itself may be made to have an electromagnetic induction heat-generating property, and the heat may be generated by the exciting means.

  Further, the pressure rotating body of the fixing device 11 is not limited to the roller body, but may be a rotating belt body.

  Further, the image carrier of the image forming apparatus is not limited to the electrophotographic photosensitive drum, and may be an electrostatic recording dielectric, or an intermediate transfer member such as an intermediate transfer drum or a belt.

4 is a flowchart of slip prevention control according to the first embodiment. FIG. 1 is a schematic configuration diagram of a laser beam printer 100. FIG. 3 is a cross-sectional view of the fixing device 11. 5 is a graph showing a relationship between a pressure roller temperature and a conveying force. 6 is a graph illustrating a pressure roller temperature difference according to a print mode. It is a result at the time of a cold start in the first embodiment. It is a result at the time of a hot start in the first embodiment. It is a flow chart of slip prevention control in a 2nd embodiment. It is a result at the time of a cold start in the second embodiment. It is a result at the time of a hot start in the second embodiment. It is a flow chart of slip prevention control in a 3rd embodiment. It is a result at the time of a hot start in the fourth embodiment. FIG. 2 is a schematic configuration diagram of a laser beam printer.

Explanation of reference numerals

Reference Signs List 1 photosensitive drum 2 charging roller 3 laser scanner 4 developing device 5 toner 6 transfer roller 7 high voltage power supply 8 transfer high voltage generator 9 transfer voltage control unit 10 rotation control unit 11 fixing device 12 paper feed device 21 film inner surface guide member 22 heater 23 Film 24 Pressure roller 25 Pressure roller core 26 Motor 27 CPU
29 Thermistor N Fixing nip N
T Transfer nip P paper

Claims (18)

Charging means for charging the image carrier to a predetermined potential,
Exposure means for exposing the image carrier to form an electrostatic latent image according to an image information signal from an external device on the image carrier charged by the charging means,
Developing means for developing the electrostatic latent image on the image carrier with a developer to form a developer image,
Transfer means for applying a transfer voltage to a transfer member to transfer the developer image on the image carrier to a recording material;
A heating member for thermally fixing the developer image to the recording material onto which the developer image has been transferred by the transfer unit, and a pressing member for conveying the recording material while pressing the recording material against the heating member. Fixing means having
Output means for outputting information about the environment where the image forming apparatus is placed;
Between the fixing operation on the recording material on which the developer image corresponding to the previous image information signal has been transferred and the fixing operation on the recording material on which the developer image has been transferred according to the next image signal, the pressing member Control means for providing a predetermined temperature reduction period for lowering the temperature,
The image forming apparatus, wherein the control unit sets the predetermined temperature reduction period based on information about the environment output from the output unit.   The image forming apparatus according to claim 1, wherein the control unit reduces the temperature of the pressing member by stopping heating by the heating member during the predetermined temperature lowering period.   The control unit controls the heating member to be maintained at a predetermined temperature in the fixing operation, and controls the heating member to maintain a temperature lower than the predetermined temperature during the predetermined temperature lowering period. The image forming apparatus according to claim 1, wherein the temperature of the pressing member is reduced.   The image forming apparatus according to claim 1, wherein the information about the environment is information about a resistance value of the transfer member.   The image according to claim 4, wherein the output unit outputs information on a resistance value of the transfer member based on the transfer voltage applied to the transfer member so that a constant current flows through the transfer member. Forming equipment.   6. The method according to claim 1, wherein the control unit sets the predetermined time when the transfer voltage is equal to or lower than a predetermined voltage to be longer than the predetermined time when the transfer voltage is higher than the predetermined voltage. An image forming apparatus according to any one of the above.   The control unit varies the time required for a predetermined end operation performed by the control unit after the fixing operation on the recording material onto which the developer image according to the previous image information signal has been transferred, thereby performing the predetermined operation. The image forming apparatus according to claim 1, wherein a temperature reduction period is set.   The control means controls the next image signal after completion of a predetermined end operation performed by the control means after the fixing operation on the recording material on which the developer image corresponding to the previous image information signal has been transferred. 8. The predetermined temperature lowering period is set by changing a time until a fixing operation on a recording material onto which a developer image is transferred according to the predetermined temperature is started. Image forming apparatus.   The image forming apparatus according to claim 8, wherein the time until the fixing operation is started is a time until the heating by the heating member is started.   2. The control device according to claim 1, wherein the control unit controls the heating member to be maintained at a predetermined temperature in the fixing operation, and changes the predetermined temperature based on information on the environment output by the output unit. 3. 10. The image forming apparatus according to any one of 9 above. Charging means for charging the image carrier to a predetermined potential,
Exposure means for exposing the image carrier to form an electrostatic latent image according to an image information signal from an external device on the image carrier charged by the charging means,
Developing means for developing the electrostatic latent image on the image carrier with a developer to form a developer image,
Transfer means for applying a transfer voltage to a transfer member to transfer the developer image on the image carrier to a recording material;
A heating member for thermally fixing the developer image to the recording material on which the developer image has been transferred by the transfer unit, and a pressing member for conveying the recording material while pressing the recording material against the heating member. Fixing means having
Detecting means for detecting the transfer voltage applied to the transfer member so that a constant current flows through the transfer member;
Between the fixing operation on the recording material on which the developer image corresponding to the previous image information signal has been transferred and the fixing operation on the recording material on which the developer image has been transferred according to the next image signal, the pressing member Control means for providing a predetermined temperature reduction period for lowering the temperature,
The control unit may set the predetermined temperature reduction period when the transfer voltage detected by the detection unit is equal to or lower than a predetermined voltage to be longer than the predetermined temperature reduction period when the transfer voltage is higher than a predetermined voltage. An image forming apparatus comprising:   The image forming apparatus according to claim 11, wherein the control unit lowers the temperature of the pressing member by stopping heating by the heating member during the predetermined temperature lowering period.   The control unit controls the heating member to be maintained at a predetermined temperature in the fixing operation, and controls the heating member to maintain a temperature lower than the predetermined temperature during the predetermined temperature lowering period. The image forming apparatus according to claim 11, wherein the temperature of the pressing member is reduced.   The control unit varies the time required for a predetermined end operation performed by the control unit after the fixing operation on the recording material onto which the developer image according to the previous image information signal has been transferred, thereby performing the predetermined operation. 14. The image forming apparatus according to claim 11, wherein a temperature reduction period is set.   The control means controls the next image signal after completion of a predetermined end operation performed by the control means after the fixing operation on the recording material on which the developer image corresponding to the previous image information signal has been transferred. 15. The predetermined temperature lowering period is set by varying a time until a fixing operation on a recording material onto which a developer image has been transferred according to the predetermined temperature is started. Image forming apparatus.   The image forming apparatus according to claim 15, wherein the time until the fixing operation is started is a time until the heating by the heating member is started.   17. The control device according to claim 11, wherein the control unit controls the heating member to be maintained at a predetermined temperature in the fixing operation, and varies the predetermined temperature based on the transfer voltage detected by the detection unit. An image forming apparatus according to any one of the above.   18. The apparatus according to claim 1, wherein the heating member includes a film member that rotates while being in contact with the recording material, and a heater member that heats a developer image on the recording material via the film member. The image forming apparatus as described in the above.

Images