This application is based on Japanese Patent Application No. 2011-63990 filed with the Japan Patent Office on Mar. 23, 2011, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to fixing devices. More particularly, the present invention relates to a fixing device which includes a temperature measuring unit capable of measuring the temperature of a surface of a heat applying rotary body.
2. Description of the Related Art
Electrophotographic image forming devices include a facsimile machine, a copier, a printer, and a multi-function peripheral (MFP) provided with the scanner function, facsimile function, copying function, function as a printer, data communicating function, and server function.
An image forming device generally forms a toner image on an image carrier using a developing roller, transfers the toner image formed on the image carrier onto a sheet of paper (transfer material), and then heats the toner image using a fixing device (fuser) to fuse it on the sheet, thereby forming an image on the sheet.
In order to reduce the electric power consumed by the image forming device, during a standby period of the image forming device, the fixing device is kept at a certain temperature that is lower than a temperature (hereinafter, referred to as a “fixable temperature”) at which the fixing device is capable of fixing a toner image. During the use of the image forming device, a heating roller is heated so as to raise the temperature of the fixing device to the fixable temperature.
An operation of returning an image forming device to a state where the device can perform printing is called “warm-up” (or a “warm-up operation”). In the warm-up operation, heat [J=W·s] of an amount that is necessary to impart a prescribed fix level to a toner image is input to components of the fixing device, so that the temperature of the fixing device is raised to the fixable temperature. The amounts of heat required to be input to the respective components of the fixing device depend on the amount of heat (storage of heat) that the fixing device retains at the start of the warm-up operation. Therefore, an optimal way of starting the image forming device varies in accordance with the state of the image forming device at the start of the warm-up operation.
The state of the image forming device may be detected by measuring the temperature of the fixing device. According to this method, the amount of heat [J] retained in the fixing device is computed on the basis of the heat capacity [J/K] of the fixing device, which is known in advance, and the temperature [K] of the fixing device. As it is not possible to measure the temperatures of all the components of the fixing device, according to this method, the temperature of a representative component is measured and, on the basis of the measured temperature, the amount of heat [J] retained in the fixing device is computed approximately. In this method, in order to more accurately compute the amount of heat [J] retained in the fixing device, it is preferable to measure the temperature [K] of a component having large heat capacity [J/K]. Conventionally, as such a component with large heat capacity [J/K], the temperature of a pressure roller has been measured directly.
Documents 1 to 3 listed below each disclose a conventional method for controlling a fixing device. In a color laser printer disclosed in Document 1 below, during warm-up processing, a pressure roller and a heating roller are rotated in a direction opposite from the paper transport direction, so as to remove waste toner and paper dust from the portion where a temperature sensor is in contact with the heating roller.
In a fixing control device disclosed in Document 2 below, in the case where a high-temperature state of a fixing belt is detected at a position where a thermistor is arranged, the fixing belt is forcibly rotated in an opposite direction, and the temperature of the fixing belt at the portion corresponding to the fixing nip portion is sensed again with the thermistor, to thereby determine whether the fixing device is in a state of abnormal temperature.
In a fixing device disclosed in Document 3 below, full electric power is supplied during a temperature regulating period at startup, and the temperature rise time of a fixing heater is measured from the temperature sensed by a sub-thermistor, to predict the maximum electric power to be supplied to the fixing device.
With the conventional methods described above, however, when an image forming device (system) does not have a temperature detecting device for a pressure roller, it is not possible to directly measure the temperature of the pressure roller, hindering accurate computation of the amount of heat being retained by the fixing device. Further, even in the case of an image forming device that can directly measure the temperature of the pressure roller, the temperature being measured is a surface temperature of the pressure roller, which does not accurately represent the amount of heat being retained inside the pressure roller. This causes an increase in user's wait time and/or wasting of electric power due to the warm-up operation. Furthermore, if the computed amount of heat being retained in the fixing device is greater than the actual amount, the amount of heat input to the fixing device may be inadequate, leading to poor image fixing performance. None of the techniques described in Documents 1 to 3 can solve these problems.
In view of the foregoing, an object of the present invention is to provide a fixing device which can reduce time necessary for a warm-up operation.
Another object of the present invention is to provide a fixing device, an image forming device which can reduce power consumption.
An aspect of the present invention provides a fixing device having a heat applying rotary body heated by a heat source, a pressure applying rotary body which comes into contact with the heat applying rotary body to form a nip portion, and a temperature measuring unit capable of measuring a temperature of a surface of the heat applying rotary body, wherein the fixing device includes: a moving unit operable to move that portion on the surface of the heat applying rotary body which was located at the nip portion at the start of a warm-up operation to a measurement location of the temperature measuring unit, the warm-up operation being an operation of bringing surfaces of the heat applying rotary body and the pressure applying rotary body to a temperature at which printing is possible; a first temperature measuring unit that uses the temperature measuring unit to measure a temperature of that portion on the surface of the heat applying rotary body moved to the measurement location by the moving unit; and a warm-up control unit that controls the warm-up operation on the basis of the temperature measured by the first temperature measuring unit.
The foregoing and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.
While a color printer is described as the image forming device in the present embodiment, the fixing device of the present invention may be adapted, not only to the color printer shown in
Referring to
Paper transport unit 200, toner image forming unit 300, and fixing device 400 combine images of four colors of black (BK), yellow (Y), magenta (M), and cyan (C) as required, using a so-called tandem system, to form a color image on a sheet of paper.
Paper transport unit 200 is configured to feed a sheet SH of paper (recording paper) set in a paper cassette 601 (recording paper cassette) to toner image forming unit 300 and fixing device 400, and discharge a sheet on which an image has been formed to a catch tray 603. Paper cassette 601 is disposed in the lower part in
Paper transport unit 200 includes a feed roller 210 and a transport roller 220. In each of feed roller 210 and transport roller 220, two opposite rollers, for example, that sandwich a sheet therebetween are rotated to thereby transport the sheet. During printing, feed roller 210 feeds sheets SH, loaded in paper cassette 601, one by one, into the interior of the housing of color printer 1000. Transport roller 220 transports the sheet fed by feed roller 210 to toner image forming unit 300. It is noted that, besides the above-described rollers, paper transport unit 200 may include, for example, a discharge roller for discharging the sheet that has passed through fixing device 400 to catch tray 603, and other rollers for use in transporting a sheet.
Toner image forming unit 300 includes: image forming units 301BK, 301Y, 301M, and 301C (hereinafter, they may also be collectively referred to as “image forming units 301”), an exposure controller 303, an intermediate transfer belt 305, four primary transfer rollers 307, and a secondary transfer roller 309. Image forming units 301BK, 301Y, 301M, and 301C are arranged at the center inside the housing of color printer 1000, side by side in this order from the upstream side to the downstream side of the running direction (indicated by an arrow A1) of intermediate transfer belt 305. Exposure controller 303 is arranged beneath image forming units 301BK, 301Y, 301M, and 301C, and intermediate transfer belt 305 is arranged above image forming units 301BK, 301Y, 301M, and 301C. Four primary transfer rollers 307 are arranged corresponding respectively to image forming units 301BK, 301Y, 301M, and 301C. Secondary transfer roller 309 is arranged in the vicinity of the paper transport path of paper transport unit 200.
Image forming units 301 each include: a photoreceptor drum 311 which rotates; an electrifying device 313 for uniformly electrifying photoreceptor drum 311; an exposure unit 315 which uses a laser beam to expose an image onto the electrified photoreceptor drum 311; a development device 317 which forms a toner image by developing the static latent image formed by exposure with toner of the corresponding color; and a cleaning blade 319 which removes and collects toner remaining on photoreceptor drum 311 after the primary transfer.
Exposure controller 303 is located so that it can scan each photoreceptor drum 311 with a laser beam via the corresponding exposure unit 315. Exposure controller 303 drives one or more exposure units 315 in accordance with the corresponding colors.
Intermediate transfer belt 305 forms a loop and is laid around, for example, three rollers 351 to 353. Intermediate transfer belt 305 is rotated in a synchronized manner with paper transport unit 200 to travel in the direction shown by the arrow A1. Secondary transfer roller 309 is arranged to face that portion of intermediate transfer belt 305 which is in contact with roller 351. The distance between secondary transfer roller 309 and intermediate transfer belt 305 is adjusted by a pressing/separating mechanism.
A toner image developed on photoreceptor drum 311 is transferred onto intermediate transfer belt 305 by primary transfer roller 307 at the position of contact with intermediate transfer belt 305. As intermediate transfer belt 305 passes through image forming units 301, the toner images of the respective colors are transferred onto intermediate transfer belt 305 so that they are superposed on one another, and finally, a full color toner image is formed on intermediate transfer belt 305. Paper transport unit 200 transports a sheet while sandwiching the same between intermediate transfer belt 305 and secondary transfer roller 309. The toner image formed on intermediate transfer belt 305 is collectively transferred onto the sheet SH by secondary transfer roller 309. The sheet with the toner image formed thereon is fed to fixing device 400. The toner remaining on intermediate transfer belt 305 after the secondary transfer is removed from the surface of intermediate transfer belt 305 by a cleaning blade 306, transported by a conveyor screw (not shown), and collected in a waste toner container (not shown).
Control unit 500 is responsible for overall control of color printer 1000. Control unit 500 transmits a signal corresponding to an image to exposure controller 303.
Fixing device 400 transports a sheet, while sandwiching it, and applies heat and pressure to the sheet. In this manner, fixing device 400 melts the toner adhering to the sheet and fixes it on the sheet, thereby forming an image on the sheet.
Referring to
Fixing device 400 is configured such that the pressure applying rotary body and the heat applying rotary body form a nip portion NP for sandwiching and transporting a sheet having a toner image (unfixed image) formed thereon. While transporting the sheet, fixing device 400 heats and presses the sheet with fixing belt 405 and pressure roller 407 so as to cause the toner image formed on the sheet to be fixed on the sheet. Thermopile 409 measures the temperature at a measurement location B1. The measurement location B1 is, for example, on a surface of that portion of fixing belt 405 which is wound around heating roller 401, and is located upstream of the nip portion NP (when the starting point is set at heating roller 401) in the rotational direction (shown by an arrow D1 in
Sizes and materials of the components of fixing device 400 are for example as follows. Heating roller 401 has an outer diameter of 25 mm and is about 330 mm long in the nip longitudinal direction. Heating roller 401 has a 0.6 mm-thick hollow core made of aluminum and a 15 μm-thick PTFE (polytetrafluoroethylene) coating which covers the core. Fixing roller 403 has an outer diameter of 30 mm, and has a 22 mm-diameter solid core made of iron, a 4 mm-thick rubber which covers the core, and a 2 mm-thick sponge which covers the rubber. Fixing belt 405 has an outer diameter of 60 mm, and has a 70 μm-thick polyimide, a 200 μm-thick rubber which covers the polyimide, and a 30 μm-thick PFA (polyfluoroalkoxy) which covers the rubber. Pressure roller 407 has an outer diameter of 35 mm, and has a 2 mm-thick core made of aluminum, a 2 mm-thick rubber which covers the core, and a 30 μm-thick PFA which covers the rubber. Heater 411 is a 999 W halogen lamp heater having a 290 mm luminous length. Thermopile 409 is arranged in non-contact with fixing belt 405 and 40 mm away from the paper feeding reference at the center. In this configuration, the heat capacity C1 as a sum of those of heating roller 401 and fixing belt 405 is smaller than the heat capacity C2 of pressure roller 407.
An operation of fixing device 400, following the turn-on of color printer 1000, to cause the surfaces of fixing belt 405 and pressure roller 407 to attain a ready temperature (a temperature at which printing is possible, a print-enabling temperature) is called a “warm-up operation”, and the time required for the warm-up operation is called “warm-up time”. Fixing device 400 also performs the warm-up operation when color printer 1000 is turned on again after being turned off, when it recovers from a paper jam, when the cover of color printer 1000 is closed, and when it wakes up from a sleep mode.
During the warm-up operation, electric power is supplied to heater 411 to turn it on, which in turn heats heating roller 401. At this time, motor 701 transmits driving force to a drive gear to rotate pressure roller 407, and cause heating roller 401, fixing roller 403, and fixing belt 405 to be driven to rotate by pressure roller 407. As a result, the heat of heating roller 401 is transmitted to the surface of fixing belt 405. When pressure roller 407 is at a high temperature, the heat of each of heating roller 401 and pressure roller 407 is transmitted to fixing belt 405. The turning on of heater 411 and the rotation of pressure roller 407 as described above cause an increase in surface temperature of fixing belt 405 and pressure roller 407.
Once the temperature measured by thermopile 409 has reached a predetermined ready temperature, fixing device 400 attains a ready state and sets a ready flag, indicating that fixing device 400 is at a temperature (ready temperature) at which printing is possible. While in the ready state, fixing device 400 enters a print standby state when no print signal is applied from control unit 500, which will be described later. During the print standby state, generally, the rotation of pressure roller 407 is stopped, and heater 411 is controlled to turn on/off such that the temperature measured by thermopile 409 is at a certain level (hereinafter, this temperature will be called the “target temperature”). On the other hand, when a print signal is applied from control unit 500, fixing device 400 starts a print operation. During the print operation, pressure roller 407 is rotated before a sheet (recording material) enters fixing device 400, to transmit the heat of heating roller 401 to the surfaces of fixing belt 405 and pressure roller 407 (if pressure roller 407 is at a high temperature, the heat of each of heating roller 401 and pressure roller 407 is transmitted to fixing belt 405). This increases the surface temperatures of fixing belt 405 and pressure roller 407.
It is noted that the fixing device is not limited to the one of a belt fixing type in which a fixing belt and a pressure roller form a nip portion, as shown in
Referring to
During the warm-up operation of this fixing device 400, electric power is supplied to heater 411 to turn it on, which in turn heats heating roller 401. At this time, a motor 701 transmits driving force to a drive gear to rotate heating roller 401, and cause pressure roller 407 to be driven to rotate by heating roller 401. As a result, the heat of heating roller 401 is transmitted to pressure roller 407. The turning on of heater 411 and the rotation of pressure roller 407 as described above cause an increase in surface temperature of heating roller 401 and pressure roller 407.
The other configuration and operation of the fixing device are identical to those of the fixing device shown in
Referring to
CPU 501 is responsible for overall control of color printer 1000. CPU 501 executes a control program stored in ROM 505. CPU 501 performs prescribed processing to read data from and write data to RAM 503 and ROM 505. CPU 501 controls an output of motor 701 to thereby control the rotation of pressure roller 407. CPU 501 adjusts the amount of electric power supply from electric power supplying unit 703 to thereby control heater 411. Furthermore, CPU 501, through the intermediary of contact adjustment unit 705, adjusts the pressure-contact state between fixing belt 405 and pressure roller 407 (or between heating roller 401 and pressure roller 407 in the fixing device shown in
RAM 503 is a main memory for CPU 501. RAM 503 is used, for example, for storing data necessary for CPU 501 to execute the control program.
ROM 505 may be, for example, a flash ROM (flash memory). ROM 505 stores various programs for an operation of color printer 1000 as well as various fixed data. ROM 505 may be non-rewritable.
HDD 507 is a storage device which stores data such as print data transmitted from the outside via communication I/F 509. Further, HDD 507 stores an evaluation table (
Communication I/F 509, in accordance with an instruction from CPU 501, communicates with an external device via a LAN, for example, by using a communication protocol such as TCP/IP.
Operation panel 707 includes a key input unit (not shown) composed of a ten key pad, a start key, and so on, and a display unit (not shown) composed of a liquid crystal touch panel or the like. Operation panel 707 is used by a user to perform various operations.
Referring to
That is, as pressure roller 407 has relatively large heat capacity, the temperature of pressure roller 407 at the start of the warm-up operation will vary depending on, for example, how and to what extent pressure roller 407 has been heated prior to the warm-up operation. Thus, fixing device 400 uses thermopile 409 to estimate the temperature of pressure roller 407, and controls the warm-up operation in accordance with the estimated temperature.
The temperature of pressure roller 407 may be estimated for example in the following manner. In fixing device 400 shown in
Here, heater 411 may be turned on before the estimation of the temperature of pressure roller 407, so that the warm-up time may be reduced. In this case, it is preferable to cause fixing belt 405 to move in the direction shown by an arrow D2 in
It is noted that thermopile 409 may be arranged at the position indicated by a broken line in
Further, thermopile 409 may measure a temperature T1 of that portion on the surface of fixing belt 405 which is located at the measurement location B1 at the start of the warm-up operation (or, before the portion of fixing belt 405 located at the nip portion NP is moved to the measurement location B1). In this case, the warm-up operation can be controlled on the basis of the temperatures T1 and T2.
Referring to
In the above flowchart, measurement of the temperature T1 may be omitted, in which case the warm-up operation is controlled on the basis of the temperature T2 alone. Further, the rotation of fixing belt 405 may be returned to the positive rotation (in the direction shown by the arrow D1 in
Now, as a specific way of setting the warm-up conditions in step S11 in
According to the first setting method, the warm-up conditions are set according to whether the temperatures T1 and T2 satisfy a prescribed expression, or more specifically, the following expression (1):
T1≧T2 (1)
The temperatures T1 and T2 satisfy the expression (1) in the case where fixing device 400 is not warm (i.e. the pressure roller is at a low temperature), as typically shown in
On the other hand, the temperatures T1 and T2 fail to satisfy the expression (1) (i.e. T1<T2) in the case where fixing device 400 is warm (i.e. the pressure roller is at a high temperature), as typically shown in
In the state where fixing device 400 is warm, setting the velocity of fixing device 400 lower and the nip width at the nip portion NP smaller than in the normal operation can reduce the transmission of the heat to pressure roller 407 which is at a high temperature. The heat can be retained at each of heating roller 401, fixing roller 403, and fixing belt 405 which are at a low temperature, and accordingly, fixing device 400 can be heated rapidly. Further, setting the ready temperature lower than in the normal operation is advantageous in that, at the time of accelerating fixing device 400 to the velocity in the normal state for performing printing after fixing device 400 attains the ready state (warmed-up state), it is possible to address the event that the temperature on the fixing belt 405 side drops steeply as the heat is rapidly taken away to the pressure roller 407 side. In the state where fixing device 400 is warm, less heat transfers to the interior of pressure roller 407 and fixing roller 403 at the nip portion NP, allowing the heat to readily be transmitted to the sheet and toner. For this reason, the target temperature of fixing device 400 is set lower than in the normal operation.
In the first setting method, different expressions may be used in accordance with the temperature T1. For example, in the case where the temperature T1 is lower than 100° C., the warm-up conditions may be set according to whether the expression (1) is satisfied. In the case where the temperature T1 is not lower than 100° C., the warm-up conditions may be set according to whether the following expression (2) is satisfied:
T1−T2≧a (2)
where “a” may be a constant or a variable (preferably, a positive value) that may change in accordance with the value of the temperature T1 (the amount of temperature drop of heating roller 401).
In the case where the temperatures T1 and T2 satisfy the above expression (2), it is determined that fixing device 400 is not warm. In the case where the temperatures T1 and T2 do not satisfy the above expression (2), it is determined that fixing device 400 is warm.
Referring to
In the second setting method, a count value of at least a part of the control time of fixing device 400 is stored in a backup area in HDD 507, and the warm-up operation is controlled on the basis of the count value read from the backup area as well as the temperatures T1 and T2. First, the way of counting the control time of fixing device 400, carried out in the second setting method, will be described.
Referring to
If it is determined in step S105 that color printer 1000 has not been turned off (NO in S105), CPU 501 determines whether the counted value has reached a prescribed value (for example, 60 seconds, 180 seconds, 600 seconds, or 1200 seconds) (S111). If it is determined in step S111 that the counted value has reached a prescribed value (YES in S111), CPU 501 stores the count value at that time in the backup area in HDD 507, to thereby update the count value stored in the backup area (S113). The process then proceeds to step S105.
If it is determined in step S111 that the count value has not reached a prescribed value (NO in S111), CPU 501 determines whether it is time to start a print operation, whether it is time to finish the print operation, or whether it is time to stop supplying electric power to heater 411 (S121). In step S121, it may be determined whether at least one of the above conditions has been satisfied. If it is determined in step S121 that it is time to start the print operation, or it is time to finish the print operation, or it is time to stop supplying electric power to heater 411 (YES in S121), CPU 501 proceeds to the processing in step S113. On the other hand, if it is determined in step S121 that it is not time to start the print operation, or time to finish the print operation, or time to stop supplying electric power to heater 411 (NO in S121), CPU 501 proceeds to the processing in step S105 while continuing the counting.
In the counting method described above, the control time is counted from zero when the temperature detected by thermopile 409 has reached 100° C. after the warm-up operation was started. The counting is continued steadily during the warm-up operation, during the standby state, and during the print operation. The count value is stored in the backup area in the device at the time when the count value has reached a prescribed value, or at the timing of state transition.
it is noted that the counting may be carried out in a way other than that described above. For example, the time from the start to the end of electric power supply to heater 411 (i.e. the time during which heater 411 is on) may be counted, or the time during which the detected (measured) temperature of heating roller 401 is higher than a specific temperature may be counted.
In the second setting method, the count value (backup value) stored in the backup area at the start of the warm-up operation is read, and the warmed level of fixing device 400 is evaluated on the basis of the read count value and the temperatures T1 and T2 by using an evaluation table shown in
Referring to
The “initial temperature” is set, for example, using the temperatures T1 and T2 and in accordance with the following expression (3):
Initial Temperature=T1+(T2−T1)×b (3)
where “b” is a coefficient, which may be a fixed value or may be variable in accordance with the value of the temperature T1.
The values 0 to 27 on the evaluation table represent the warmed levels of fixing device 400. The larger number indicates that fixing device 400 is warmed to a greater degree.
It is noted that, instead of setting the initial temperature using the expression (3), the temperature T1 as it is may be set as the initial temperature. Further, a plurality of evaluation tables may be stored in HDD 507, and the evaluation table to be used may be selected therefrom depending on the value of (T2−T1). Furthermore, a value for adjusting the warmed level in accordance with the value of (T2−T1) may be added to an evaluation table.
Further, in the second setting method, instead of using an evaluation table, the following expression (4), for example, may be used to evaluate the warmed level of fixing device 400:
Warmed Level=B×Count Value×(Initial Temperature−A) (4)
where “A” and “B” are coefficients, which may be fixed values or may be variable in accordance with the value of the temperature T1.
In the second setting method, if the value indicating the warmed level is less than 3, for example, it is determined that fixing device 400 is not warm. In this case, the warm-up operation is carried out in a normal operation. As the exemplary warm-up conditions in the normal operation, the velocity (linear velocity) of the fixing device is set to 100 m/s, fixing roller 403 and pressure roller 407 are brought into a pressure contact state, the target temperature of fixing device 400 is set to 185° C., and the ready temperature is set to 165° C.
On the other hand, if the value indicating the warmed level is 3 or more, for example, it is determined that fixing device 400 is warm. In this case, compared to the case where fixing device 400 is cool, the velocity (linear velocity) of the fixing device is set lower than in the normal operation, the nip width of the nip portion NP between fixing roller 403 and pressure roller 407 is set smaller than in the normal operation (for example, a separate state), the target temperature of fixing device 400 is set lower than in the normal operation, and the ready temperature is set lower than in the normal operation. It is noted that not all these warm-up conditions have to be set; at least one of these conditions may be set. As the exemplary conditions to be set, the velocity (linear velocity) of the fixing device is set to 50 m/s, fixing roller 403 and pressure roller 407 are brought into a separate state, the target temperature of fixing device 400 is set to 180° C., and the ready temperature is set to 175° C.
Referring to
If it is determined in step S57 that the value of the evaluated warmed level of fixing device 400 is 3 or more (YES in S57), CPU 501 sets fixing device 400 at a low speed, sets pressure roller 407 to a separate state (with a smaller nip width), and sets the ready temperature and the target temperature to low temperature (S59), before returning to the main routine. On the other hand, if it is determined in step S57 that the value of the evaluated warmed level of fixing device 400 is less than 3 (NO in S57), CPU 501 sets fixing device 400 at a high speed, sets pressure roller 407 to a pressure contact state (with a greater nip width), and sets the ready temperature and the target temperature to high temperature (S61), before returning to the main routine.
Referring to
Referring to
Fixing device 400 and color printer 1000 equipped with the same in the present embodiment are configured to calculate the overall storage of heat in fixing device 400 at the time of return operation from a sleep mode or the like, on the basis of the temperatures T1 and T2 (start temperatures) and the past control history, to thereby perform an optimal warm-up operation in accordance with the storage of heat.
According to fixing device 400 and color printer 1000 equipped with the same in the present embodiment, the temperature T2 of that portion on the surface of fixing belt 405 which was located at the nip portion NP with pressure roller 407 at the start of the warm-up operation is measured to estimate the temperature of pressure roller 407, and the warm-up operation is controlled in accordance with the estimated temperature of pressure roller 407. This ensures that the heat being retained in fixing device 400 (the heat retaining state of fixing device 400) at the start of the warm-up operation is calculated with accuracy. It is known in advance what amount of heat is required for which part in order to satisfy a desired fix level. Thus, an optimal way of inputting the heat can be selected on the basis of the measured temperature. As a result, the time required for the return operation can be reduced, and the user's wait time for the device to wake up from the sleep mode can be shortened. Furthermore, wasteful heat consumption and, hence, electric power consumption can be reduced.
Particularly in the case where the second setting method is adopted, the heat stored in fixing device 400 can be calculated and the warmed level of fixing device 400 can be estimated more accurately on the basis of the past heating history and the temperatures T1 and T2 at present. The startup method thereafter can then be changed by using the estimated warmed level as an input, so that the return time can be reduced.
According to the above embodiment, it is possible to provide a fixing device capable of reducing the time required for a warm-up operation, an image forming device and a method and program for controlling the fixing device. Further, according to the above embodiment, it is possible to provide a fixing device capable of reducing electric power consumption, an image forming device, and a method and program for controlling the fixing device.
As the temperature measuring unit for measuring the surface temperature of the heat applying rotary body, a thermistor or a thermocouple, for example, may be used in place of the thermopile. As the heat source, a resistance heating element or an induction heating (IH) apparatus may be used in place of the heater. Furthermore, the heat source is not restricted to the one that heats the heat applying rotary body from inside, as in the above-described embodiment; it may be the one that heats the heat applying rotary body from outside.
The motor may be configured to give driving force to the heat applying rotary body instead of or in addition to, giving driving force to the pressure applying rotary body.
The conditions and settings of the fixing device in the above embodiment are only illustrative; other conditions and settings may be adopted instead.
The features of the embodiment described above may be combined as appropriate. For example, the fixing device having the configuration shown in
The processes according to the above embodiment may be performed by software or by using a hardware circuit.
A program for executing the processes according to the above embodiment may be provided as well. The program may be recorded on a recording medium, such as a CD-ROM, flexible disk, hard disk, ROM, RAM, memory card, or the like, so as to be provided to a user. The program is executed by a computer such as a CPU. The program may also be downloaded to the device via a communication line such as the Internet.
Although the preset invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Number | Date | Country | Kind |
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2011-063990 | Mar 2011 | JP | national |