JP4295564B2 - Fixing apparatus and rotation control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device for fixing a toner image (image) to a fixing medium in an image forming apparatus such as an electrostatic copying machine or a laser printer. The present invention also relates to a rotation control method for a press roller included in the fixing device.
[0002]
[Prior art]
2. Description of the Related Art A roller type heating / pressure fixing device is known as one of fixing devices used for copying machines and printers employing an electrophotographic system. The fixing device includes a heat roller heated to a high temperature and a press roller that presses the recording paper against the heat roller. The fixing device fixes the unfixed image on the recording paper with heat and pressure by passing the unfixed image on the recording paper through a nip portion (action portion) formed by a heat roller and a press roller.
[0003]
The heat roller and the press roller of the copying machine and the printer during the ready are controlled so as to maintain the respective set temperatures. The heat roller is heated by a heat source such as a heater to maintain a set temperature, and the press roller receives heat from the heat roller by rotating the heat roller and the press roller idle (pre-run), and is heated to maintain the set temperature. However, the press roller becomes constant at a certain temperature with the passage of time, but when this temperature is within the control temperature range of the press roller, no idle rotation (pre-run) is performed thereafter, and the press roller is stationary at the same position ( Stop. For this reason, permanent deformation may occur in the press roller.
[0004]
Conventionally, a press roller has been provided with a rubber layer having high rubber hardness on the surface of the core metal. However, in order to save energy in the fixing device, the number of press rollers provided with a rubber layer having a low heat capacity is increasing. In general, a rubber layer having a low heat capacity is weaker to pressurization for a long time than a rubber layer having a high rubber hardness, and permanent deformation is likely to occur. When permanent distortion occurs, image defects (gloss unevenness) and abnormal noise occur.
[0005]
As a method for preventing permanent distortion, a method of changing the stationary position (stop position) by increasing the control temperature of the press roller above a constant temperature, increasing idling (pre-run), and the like. However, since the number of idling (pre-run) increases, there are disadvantages that the life of the heat roller and the press roller is shortened and energy consumption is increased.
[0006]
There is also a method in which the press roller is not pressed against the heat roller except during printing (see Patent Document 1). In addition, there is a method of switching the pressing load of the press roller to the heat roller in two stages (see Patent Document 2). Furthermore, there is a method of rotating the press roller at an ultra-low speed during standby (see Patent Document 3).
[0007]
[Patent Document 1]
JP-A-5-53473
[0008]
[Patent Document 2]
JP-A-10-293497
[0009]
[Patent Document 3]
JP-A-8-95416
[0010]
[Problems to be solved by the invention]
However, the permanent distortion prevention measures described in Patent Documents 1 and 2 have a problem that the mechanism becomes complicated and expensive. In addition, the above-described permanent distortion prevention measures disclosed in Patent Document 3 improve the life of the heat roller and the press roller by the problem of image deterioration due to excessive oil supply to the heat roller and the press roller, and the occurrence of scars by the peeling claw and the thermistor. It becomes a factor to shorten.
[0011]
An object of the present invention is to provide a fixing device and a rotation control method that are made to solve the above-described problem and that can efficiently prevent distortion of a press roller.
[0012]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, for example, a fixing device of the present invention is configured as follows.
[0013]
The present invention is a fixing device including a pair of heat rollers and a press roller for fixing a toner image to a fixing medium by heat and pressure, a rotating means for rotating the press roller, and the press roller Detecting means for detecting the stop time, and rotation control means for rotating the press roller by the rotating means based on the detection result of the stop time by the detecting means.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an image forming apparatus to which an example of an embodiment of the present invention can be applied will be described with reference to the drawings. Here, an example of the embodiment will be described by taking a digital copying apparatus as an example.
[0015]
As shown in FIG. 1, a digital copying apparatus (image forming apparatus) 101 captures an image of interest as light and dark and photoelectrically converts it to generate an image signal, and a scanner 102 or The image forming unit 103 includes an image forming unit 103 that forms an image corresponding to an image signal supplied from the outside and fixes the image on a sheet P that is a member to be fixed (transfer object). The scanner 102 is integrally provided with an automatic document feeder (ADF) 104 that sequentially replaces the copy target in conjunction with the image reading operation by the scanner 102 when the copy target is a sheet. .
[0016]
When the image forming unit 103 is irradiated with light in a state where a predetermined potential is applied, the potential of the region irradiated with the light changes, and the change in the potential can be held as an electrostatic image for a predetermined time. The photoconductor has a cylindrical photoconductor drum 105 formed on the outer peripheral surface.
[0017]
Image information is exposed on the photosensitive drum 105 from an exposure device 106 that can output a laser beam whose light intensity is changed in accordance with image information supplied from the scanner 102 or an external device. As a result, an electrostatic image, that is, an image is formed on the photosensitive drum 105.
[0018]
The image formed on the photosensitive drum 105 is visualized by selectively supplying toner (developer) by the developing device 107.
[0019]
The toner aggregate on the photosensitive drum 105 developed by the toner supplied from the developing device 107, that is, the toner image, is supplied with a voltage for transfer from a transfer device (not described in detail). The image is transferred to the transfer material P fed by the sheet feeding / conveying section.
[0020]
The toner image transferred to the transfer material P is melted by application of heat and pressure by the fixing device 1 and fixed (fixed) to the transfer material P (with the pressure provided by the fixing device).
[0021]
In such an image forming apparatus, an image signal is supplied from the scanner 102 or an external apparatus, and a laser beam not described in detail from the exposure apparatus 106 is applied to a predetermined position of the photosensitive drum 105 that is charged in advance to a predetermined potential. Irradiated. The intensity of the laser beam from the exposure device 106 is modulated in accordance with the image signal. As a result, an electrostatic latent image corresponding to an image to be copied (output) is formed on the photosensitive drum 105.
[0022]
The electrostatic latent image formed on the photosensitive drum 105 is developed by selectively providing toner from the developing device 107, and converted into a toner image (not shown).
[0023]
The toner image on the photoconductive drum 105 is transferred to a transfer body supplied to the transfer position, that is, the paper P, at a transfer position facing a transfer device without a reference numeral. Although not described in detail, the paper P is picked up one by one from the paper cassette 108 by the pickup roller 109, and is transported to the aligning roller 111 in advance through a transport path 110 defined between the photosensitive drum 105 and the cassette 108. Has been. The sheet P is fed to the transfer position with the feeding timing aligned in order to align the position with the toner image formed on the photosensitive drum 105 by the aligning roller 111.
[0024]
The toner transferred onto the paper P by the transfer device is conveyed to the fixing device 1. The toner on the paper P is fixed on the paper P by the pressure applied by the fixing device 1 at the same time as the toner is melted.
[0025]
The paper P on which the toner image is fixed by the fixing device 1 is discharged by a paper discharge roller 112 to a paper discharge tray 113 which is a space defined between the paper cassette 108 and the scanner 102 and is sequentially stacked.
[0026]
FIG. 2 is a schematic diagram illustrating an example of a fixing device used in the image forming apparatus illustrated in FIG.
[0027]
The fixing device 1 includes a heat roller 2 having an outer diameter of approximately 50 mm and a press roller 3 having an outer diameter of approximately 50 mm.
[0028]
The heat roller 2 is made of a metal pipe such as iron having a thickness of about 1 mm as a base material, and the surface thereof is coated with Teflon (polytetrafluoroethylene, trade name). In addition, as a roller material of the heat roller 2, stainless steel, aluminum, an alloy of stainless steel and aluminum, or the like can be used.
[0029]
Further, an IH coil 11 is disposed inside the heat roller 2 as a heat source. The IH coil 11 is formed to have a length that can heat the width contacting the outer peripheral surface of the heat roller 2 when, for example, A4 size paper is conveyed so that the short side is parallel to the axis of the roller 2. .
[0030]
The IH coil 11 is formed by a litz wire in which a plurality of wire rods, for example, 16 wires are bundled with heat-resistant polyamide imide, each having a wire diameter of, for example, 0.5 mm. By forming the IH coil 11 with a litz wire, a high-frequency current can be effectively passed.
[0031]
The IH coil 11 is an air-core coil fixed to a coil holder 12 made of, for example, engineering plastics or ceramic that has high heat resistance and high insulation properties.
[0032]
For the coil holder 12, for example, PEEK (poly ether ether ketone) material, phenol material, unsaturated polyester, or the like can be used.
[0033]
Moreover, the winding method of the wire which forms the IH coil 11 can utilize arbitrary winding methods, and in the example shown in FIG. 2, the shape of the coil holding body 12 is characterized, and a planar coil is made into the heat roller 2. It is a shape along the inner periphery of.
[0034]
A density sensor 13 for monitoring the degree of toner (offset toner) adhering to the surface of the roller 2 is provided at a predetermined position near the outer peripheral surface of the heat roller 2, for example, in the vicinity of the peeling claw 5. Yes.
[0035]
The press roller 3 has a hardness of 58 ° (ASKER-C hardness), a silicon sponge layer 3b having a predetermined thickness is formed on the outer periphery of the core metal 3a, and a PFA tube 3c having a thickness of 50 μm is formed on the outer periphery of the silicon sponge layer 3b. It consists of a structure coated with.
[0036]
The press roller 3 is substantially parallel to the axis of the heat roller 2 and is pressed against the axis of the heat roller 2 by a pressure mechanism 4 at a pressure of about 400 N. Thereby, a part of outer peripheral surface of the heat roller 3 is elastically deformed, and a nip of about 10 mm is formed between both rollers.
[0037]
The heat roller 2 is rotated in the direction of the arrow at a substantially constant speed by a fixing motor 123 (FIG. 3) or a drum motor 121 (FIG. 3) that rotates the photosensitive drum 105.
[0038]
Since the press roller 3 is in contact with the heat roller 2 with a predetermined pressure by the pressure mechanism 4, the press roller 3 is rotated at a constant speed together with the heat roller 2 by rotating the heat roller 2.
[0039]
A nip is provided at a predetermined position on the circumference of the heat roller 2 downstream of the nip (contact point) between the heat roller 2 and the press roller 3 in the direction in which the roller 2 rotates and in the vicinity of the nip. A peeling claw 5 for peeling the paper P to be passed from the heat roller 2 is located.
[0040]
Around the heat roller 2, a web cleaning mechanism 6 and a thermistor 7 are arranged in order along the direction in which the roller 2 is rotated and away from the peeling claw 5.
[0041]
The web cleaning mechanism 6 removes (cleans) the toner offset on the heat roller 2 and paper dust from the paper that is the transfer material. The web cleaning mechanism 6 is a mixed fiber of aramid fiber and PET and has a thickness of 54 μm. The web cleaning mechanism 6 is brought into contact with the heat roller 2 by a pressing roller 24 made of silicon sponge and having a hardness of 37 ° (ASKER-C). The web cleaning mechanism 6 is controlled to take up 0.3 mm for every 10 prints. In addition, the web cleaning mechanism 6 contains 19 g / m of silicon oil having a viscosity of 10,000 CS. ² Impregnated. Thereby, the web cleaning mechanism 6 applies oil to prevent offset and improve peelability simultaneously with cleaning.
[0042]
The thermistor 7 is used for detecting the temperature of the surface of the heat roller 2. The thermistor 7 can be provided at any position on the circumference of the roller 2 (the phase does not need to be set when viewed from the cross-sectional direction). Two or more thermistors may be provided. Based on the detection result of the surface temperature by the thermistor 7, the heating of the heat roller by the IH coil 11 is controlled.
[0043]
The thermistor 8 for detecting the temperature of the peripheral surface of the press roller 3 is provided on the outer peripheral surface of the press roller 3, the oil roller 9 having an outer diameter of 28 mm for applying a release agent of, for example, silicon oil to the peripheral surface of the press roller 3, and the press A cleaning roller 10 having an outer shape of 28 mm for removing toner and the like attached to the peripheral surface of the roller 3 is provided.
[0044]
The thermistor 8 is used for temperature control for keeping the temperature of the press roller 3 within a certain range. In the oil roller 9, heat resistant paper (not shown) is wound as an oil diffusing member around an outer periphery of an oil tank (not shown), and a felt layer (not shown) is formed thereon as an oil control material. The oil viscosity in the oil tank is 60,000 CS.
[0045]
FIG. 3 is a schematic diagram for explaining an example of a control circuit block for operating the fixing device shown in FIG.
[0046]
Inside the heat roller 2 of the fixing device 1 is housed an IH coil 11 for generating heat by generating an eddy current in the metal material of the heat roller 2 itself as described above. An excitation unit 31 is connected to the IH coil 11 for supplying a high frequency output of a predetermined frequency to the IH coil 11.
[0047]
The excitation unit 31 is a switching circuit 32 that can output a high-frequency output of a predetermined frequency supplied to both ends of the IH coil 11, and a drive control unit that supplies a control signal for causing the switching circuit 32 to output a high-frequency output of a predetermined frequency. 33. The switching circuit 32 is supplied with a DC voltage from a rectifier circuit 131 that rectifies an AC voltage received from a commercial power source and supplies a DC voltage. The drive control unit 33 receives the rectified output output from the rectifier circuit 131 in order to suppress the influence of the change in voltage returned via the switching circuit 32 when the output of the IH coil 11 is changed. The drive voltage that is made constant by the constant voltage circuit 132 is used.
[0048]
The drive control unit 33 is connected to the main control device 151 on the image forming unit 103 side through an interface 150. In addition, the drive control unit 33 includes an output of the thermistor 7 that is a detection output that detects the temperature of the peripheral surface of the heat roller 2 and an output of the thermistor 8 that is a detection output that detects the temperature of the peripheral surface of the press roller 3. The frequency to be output by the switching circuit 32 is obtained in accordance with the control signal input from the image forming unit 103, and the frequency of the high frequency output to be output by the switching circuit 32 is set.
[0049]
Connected to the main controller 151 on the image forming unit 103 side is a motor drive circuit 152 that rotates a motor described below at a predetermined rotational speed (speed).
[0050]
For example, the copying apparatus 101 shown in FIG. 1 includes a drum motor 121 that rotates the photosensitive drum 105 at a predetermined rotational speed, a fixing motor 123 that rotates the heat roller 2 of the fixing apparatus 1, and a web collection of the web cleaner 6. A web motor 125 that rotates the body 23 is used.
[0051]
Therefore, when an arbitrary motor rotation is instructed from the main controller 151, a predetermined number of motor drive signals (motor drive pulses) are supplied from the motor drive circuit 152 to the corresponding motor. As described above, the fixing motor 123 may be omitted and the rotation of the drum motor 121 may be transmitted to the heat roller 2.
[0052]
When the heat roller 2 is rotated by the fixing motor 123, the press roller 3 is heated by the heat roller 2 while being driven to rotate as the heat roller 2 rotates. The unfixed toner transferred to the paper P passes through the nip, contacts the heat roller 2, and is fixed to the paper P by heat and pressure.
[0053]
Further, the main controller 151 is connected to a counter 114 that checks whether a sheet on which toner fixing by the fixing device 1 has been completed is discharged. As the count value, for example, the output of the discharge jam sensor can be used.
[0054]
For example, the ROM 153 can supply the main controller 151 with the timing (conditions) for moving the web 21 and the web feed amount corresponding to each condition, that is, the amount by which the web collection body 23 is rotated. Note that the web feed amount stored in the ROM 153 can be arbitrarily changed from, for example, the control panel 141 connected to the main controller 151.
[0055]
The main controller 151 is also connected to a temperature sensor 161 that detects the temperature at a predetermined position inside the image forming unit 103, for example, the temperature in the vicinity of the photosensitive drum 105. The main controller 151 (which may be the drive controller 33) includes a clock generator R that outputs the clock CLK and a counter C that counts the clock CLK generated by the clock generator R.
[0056]
Subsequently, temperature control in the heat roller 2 and the press roller 3 will be described. During the ready, the heat roller 2 and the press roller 3 are controlled so as to maintain the set temperature.
[0057]
On / off of the IH heater 11 is controlled by the main control unit 151 functioning as temperature control means so that the temperature value (T1) of the heat roller 2 is maintained at around 200 ° C. That is, when the temperature value (T1) of the heat roller detected by the thermistor 7 falls below 200 ° C., the heater ready signal S1 is supplied (ON) to the IH heater 11 and the heat roller 2 is heated. When the temperature value (T1) of the heat roller detected by the thermistor 7 exceeds 200 ° C., the heater ready signal S1 to the IH heater 11 is stopped (OFF), and the heating of the heat roller 2 is stopped.
[0058]
The rotation of the press roller 3 is controlled by the main controller 151 functioning as a rotation control means so that the temperature value (T2) of the press roller 3 is maintained in the range of 70 to 100 ° C. Specifically, the rotation of the heat roller 2 is controlled, and the press roller 3 rotates in response to the rotation of the heat roller 2. When the temperature value (T2) of the press roller detected by the thermistor 8 falls below 70 ° C., the motor drive signal (S2) is supplied (ON) to the fixing motor 123, and the heat roller 2 and the press roller 3 are idled. (Pre-run), heat is applied from the heat roller 2 to the press roller 3, and the press roller is heated to 100 ° C. When the temperature value (T2) of the press roller detected by the thermistor 8 exceeds 100 ° C., the motor drive signal (S2) to the fixing motor 123 is stopped (OFF), and the rotation of the heat roller 2 and the press roller 3 is stopped. .
[0059]
As time passes, the temperature of the press roller 3 becomes constant at a certain temperature. When this constant temperature is within the control temperature range of 70 to 100 ° C. of the press roller 3, idling (pre-run) is not performed, and the press roller 3 is in a stationary state (stopped state). If this stationary state continues for a long time, permanent deformation occurs in the press roller 3.
[0060]
FIG. 4 is a diagram showing the relationship between the rest time (leaving time) and the permanent strain amount (creep amount). As one method of preventing image defects (gloss unevenness) and abnormal noise due to permanent distortion, the control temperature of the press roller 3 is increased, idling (pre-run) is increased, and a stationary position is set before permanent distortion occurs. There is a way to change. However, since the number of idling (pre-run) increases, there arises a new problem that the life of the heat roller 2 and the press roller 3 is shortened. Furthermore, a new problem such as an increase in energy consumption occurs because the press roller 3 is kept at a high temperature. For example, when the pre-run start temperature is 70 ° C., the creep amount is 450 μm and the energy consumption is 11 Wh. Under the prerun starting temperature of 90 ° C., the creep amount is 350 μm and the energy consumption is 35 Wh. Under the prerun start temperature of 110 ° C., the creep amount is 100 μm and the energy consumption is 77 Wh. Therefore, unless a special mechanism such as a pressure release mechanism of the press roller 3 is provided, permanent distortion cannot be prevented and energy saving cannot be achieved.
[0061]
In order to solve this, the present invention changes the stationary position (position where the nip is formed) of the press roller 3 when the temperature value of the press roller 3 becomes constant and the stationary state of the press roller 3 continues for a long time. For the purpose, the press roller 3 is idled (pre-run). This idling control is different from the idling control corresponding to the temperature control of the press roller 3.
[0062]
Hereinafter, a rotation control method according to an example of the present invention will be described with reference to FIG. When the digital copying apparatus (image forming apparatus) 101 is ready (ST1), counting of the number of times the heater ready signal is turned on and the rest time of the press roller 3 is started (ST3). The heater ready signal is a signal output from the drive control unit 33 to the switching circuit 32, and the number of times the heater ready signal is turned on is counted by the main controller 151 (counter C) that monitors the drive control unit 33. Is done. The main controller 151 (counter C) also counts the stationary time of the press roller 3, that is, the time when the motor drive signal is not supplied from the motor drive circuit 152 to the fixing motor 123. That is, the main controller 151 functions as a detection unit that detects the temperature control state by turning on / off the heater ready signal and the rotation state of the press roller.
[0063]
If a copy operation occurs during counting of the number of times the heater ready signal is turned on and the rest time of the press roller 3 (ST3, YES), both count values are cleared (ST7). Also, when idling (pre-run) for temperature control of the press roller 3 is performed (ST4, YES), both count values are cleared (ST7).
[0064]
If the copying operation does not occur (ST3, NO), and the idling for temperature control of the press roller 3 is not performed (ST4, NO), the number of times the heater ready signal is turned on and the rest time of the press roller 3 Based on the both count values, the main control unit 151 executes distortion prevention rotation control of the press roller. For example, when the number of times the heater ready signal is turned on is 200 times or more and the stationary time is 30 minutes or more (ST5, YES), the main control unit 151 executes distortion prevention rotation control of the press roller. (ST6). By controlling the rotation of the press roller to prevent distortion, for example, the press roller 3 is idled (pre-run) at a low speed of 10 seconds, the stationary position of the press roller 3 is changed, and permanent distortion is prevented. When the low-speed idling (pre-run) is finished, both the heater ready signal ON count and the rest time count values are cleared (ST7). The above processing continues until the ready state is canceled and the apparatus stops (ST8).
[0065]
If the distortion prevention rotation control of the press roller is executed based solely on the stationary time of the press roller 3, wasteful idle rotation (pre-run) occurs. That is, when the idling (pre-run) for the copy operation or the temperature control of the press roller 3 is performed, the idling for preventing the press roller from being distorted is unnecessary. In order to prevent unnecessary idling (pre-run) (to avoid wasting unnecessary energy), both the number of times the heater ready signal is turned on and the stationary time are counted, and the press roller is counted based on both count values. Executes anti-distortion rotation control. When the idling (pre-run) for the copy operation or the temperature control of the press roller 3 is performed, both count values are cleared.
[0066]
For example, the reason for setting the stationary time, which is one of the execution conditions of the distortion prevention rotation control of the press roller, to 30 minutes or more is as follows. When the number of times of heating of the heat roller 2, that is, the number of times the heater ready signal is turned on, such as immediately after warming up or in a low temperature environment increases, idle rotation (pre-run) more than necessary for preventing permanent distortion is performed. This is to prevent such idling more than necessary and minimize the increase in energy consumption. Thereby, it is possible to realize both prevention of permanent distortion and energy saving.
[0067]
The present invention described above is summarized as follows.
[0068]
Separately (independently) from idling (pre-run) by normal temperature control of the press roller 3, both the heater ready signal ON count and the stationary time are counted. For example, the heater ready signal ON count is 200 times or more and When the stationary time becomes 30 minutes or more, the stationary position is changed to prevent permanent distortion by performing a low speed idling (pre-run) for 10 seconds. As a result, a complicated mechanism for separating the press roller 3 from the heat roller 2 during the ready is not required. Therefore, permanent deformation of the press roller 3 can be prevented without increasing the cost. Furthermore, since it is not necessary to set the temperature of the press roller 3 higher than necessary, it is possible to realize both prevention of permanent distortion and energy saving.
[0069]
In the fixing device, the image forming apparatus, and the rotation control method of the present invention, when the number of times the heater ready signal is turned on is equal to or greater than the predetermined number and the stationary time is equal to or longer than the predetermined time, the press roller 3 is predetermined. You may make it rotate only a rotation angle (or only for predetermined time). For example, if it is rotated about 10 ° to 15 ° (rotation of about 1 second), distortion can be prevented. In addition, the power consumption at this time is extremely small.
[0070]
Alternatively, in the fixing device, the image forming apparatus, and the rotation control method of the present invention, a plurality of press rollers 3 are provided when the heater ready signal is turned on a predetermined number of times or more and the stationary time is a predetermined time or more. You may make it rotate (2 half rotation, 3 half rotation, etc.). In this way, by rotating a plurality of times, distortion can be prevented and the surface temperature of the press roller 3 can be made uniform. That is, it can also serve as part of temperature control.
[0071]
Furthermore, in the fixing device, the image forming apparatus, and the rotation control method of the present invention, the number of times the heater ready signal is turned on is equal to or more than a predetermined number included in the range of 200 to 350 times, and the stationary time is 20 minutes to You may make it perform the distortion prevention rotation control of a press roller, when it becomes more than predetermined time included in the range for 1 hour 20 minutes. The creep amount indicating the amount of distortion that adversely affects image quality or the like is approximately 250 μm (see FIG. 4). When the rest time of the press roller 3 is about 1 hour, the creep amount is 100 μm to 150 μm. The energy consumed to rotate the press roller 3 for about 10 seconds is about 1 to 3 Wh. That is, a sufficient effect can be obtained by simply rotating the press roller 3 for about 10 seconds per hour.
[0072]
In this embodiment, the fixing device that fixes the toner image to the transfer material P conveyed from the bottom to the top has been described. However, the present invention is not limited to such a fixing device. For example, the present invention can be applied to a fixing device that fixes a toner image to a transfer material that is conveyed horizontally, and the same effect can be obtained. Further, the IH coil 11 is not limited to the type described above, and may be, for example, a type divided into a plurality of types.
[0073]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. In addition, the embodiments may be appropriately combined as much as possible, and in that case, the combined effect can be obtained. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.
[0074]
【The invention's effect】
An object of the present invention is to provide a fixing device and a rotation control method capable of efficiently preventing a press roller from being distorted.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an example of the present invention.
FIG. 2 is a cross-sectional view illustrating a schematic configuration of a fixing device applied to the image forming apparatus illustrated in FIG.
FIG. 3 is a control block diagram for operating the fixing device shown in FIG. 2;
FIG. 4 is a diagram showing a relationship between a press roller stationary time (leaving time) and a permanent strain amount (creep amount).
FIG. 5 is a flowchart showing an example of rotation control according to an example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fixing device, 2 ... Heat roller, 3 ... Press roller, 4 ... Pressure mechanism, 5 ... Peeling claw, 6 ... Web cleaning mechanism, 7 ... Thermistor, 8 ... Thermistor, 9 ... Oil roller, 10 ... Cleaning roller, DESCRIPTION OF SYMBOLS 11 ... IH coil, 12 ... Coil holder, 13 ... Density sensor, 32 ... Switching circuit, 33 ... Drive control part, 101 ... Digital copying apparatus (image forming apparatus), 102 ... Image reading apparatus (scanner), 103 ... Image Forming sections 103, 123 ... fixing motor, 151 ... main control device, 152 ... motor drive circuit

Claims (5)

A fixing device comprising a pair of heat rollers and a press roller for fixing a toner image to a fixing medium by heat and pressure,
First temperature value detecting means for detecting a temperature value of the heat roller;
Based on the temperature value detection result by the first temperature value detection means, the temperature control means for controlling the on / off of the heat source for heating the heat roller and counting the number of times the heat source is turned on,
A rotating means for rotating the press roller;
Counting means for counting the rest time of the press roller;
A first rotation control means for rotating the press roller by the rotation means when the heat source is turned on a predetermined number of times or more and the stationary time is a predetermined time or more ;
A fixing device comprising: The rotating means is means for indirectly rotating the press roller corresponding to the rotation of the heat roller by directly rotating the heat roller,
Second temperature detecting means for detecting a temperature value of the press roller;
Second rotation control means for rotating the press roller based on a temperature detection result by the second temperature value detection means;
The fixing device according to claim 1, further comprising: A method for controlling rotation of a pair of heat rollers and a press roller for fixing a toner image to a fixing medium by heat and pressure,
Based on the detection result of the temperature value of the heat roller, the on / off of the heat source for heating the heat roller is controlled, and the number of times the heat source is turned on is counted.
When the number of times the heat source is turned on is equal to or greater than a predetermined number and the stationary time of the press roller is equal to or greater than a predetermined time, the press roller is rotated .
And a rotation control method.   The temperature control unit clears the heat source ON count when the copy operation is performed, and the count unit clears the press roller stationary time count. Fixing device.   The temperature control means clears the heat source on count when the press roller is rotated, and the count means clears the rest time count of the press roller. The fixing device described.

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