JP3893194B2 - Fixing device for image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heating type fixing device in a full-color electrophotographic image forming apparatus such as a facsimile machine or a printer having a copying machine or a heating type fixing device.
[0002]
[Prior art]
In the image forming apparatus, the fixability is mainly determined by the fixing roller temperature, the nip, and the like, but a certain part depends on the temperature environment, especially the transfer paper temperature. Therefore, a technique for changing the control temperature during operation of the fixing roller according to the temperature environment and the transfer paper temperature has been disclosed.
[0003]
For example, Japanese Patent Laid-Open No. 52-17826 discloses a control method based on a fixing temperature calculation formula in which an environmental temperature is added. Japanese Patent Application Laid-Open No. 58-136073 discloses a technique for setting the operation stop temperature when performing recording only once higher than the temperature when performing recording twice or more when the amount of heat is insufficient. Japanese Laid-Open Patent Publication (Kokai) discloses a technique for making the amount of heat applied to fixing when recording only once lower than the temperature when performing recording twice or more.
[0004]
[Problems to be solved by the invention]
However, in recent years, color image forming apparatuses also require double-sided images, and medium-thick paper (corresponding to 90 kg) having a certain thickness is used so that back-side images cannot be seen when performing double-sided copying. Has increased. However, this medium-thick paper has a problem that the heat amount is insufficient in the normal paper mode and fixing failure occurs, and in the thick paper mode, the heat amount becomes excessive and hot offset or glossiness becomes high. There was a problem that it was difficult.
[0005]
In view of this, Japanese Patent Application Laid-Open No. 7-114290 proposes an image forming apparatus that controls the fixing temperature by correcting the environmental temperature.
However, since the image forming apparatus provides a sufficient amount of heat for fixing even when the transfer paper temperature is low in a low temperature environment, for example, if the second side is copied as it is, Since the temperature has risen, problems such as hot offset due to excessive heat quantity or high glossiness may occur.
[0006]
In general, when a photosensitive member forms one type of color image, it is necessary to superimpose toners of four colors of yellow, magenta, cyan, and black, which requires a lot of time in the image forming process. And Therefore, in the case of double-sided copying, the temperature of the transfer paper varies greatly between when copying the second side immediately after copying the first side and when copying after a long time has passed. If the temperature of the fixing roller is controlled in accordance with the case where the second side is copied immediately, if the temperature of the transfer paper is lowered after a long time, a fixing defect due to insufficient heat occurs. It was supposed to end.
[0007]
Furthermore, the color image forming apparatus has image forming conditions in various modes such as a full color mode, a mono color mode (monochrome mode), a black and white mode, a character mode, a photo mode, a high-definition mode, and a cardboard mode. It is necessary to finely control the temperature so as to respond.
[0008]
The present invention has been made to solve the above problems. First, in the case of double-sided copying, it is possible to satisfy both the fixing properties of both sides. ,And, An object of the present invention is to provide a fixing device of an image forming apparatus that does not cause a fixing failure due to a lack of heat even when copying on the second side using a transfer paper that has been stacked on a double-sided tray for a long time and the surface temperature is lowered. Yes.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a fixing device of an image forming apparatus according to the present invention includes a fixing roller that is controlled so that the surface temperature becomes a preset temperature, and roller temperature detection that detects the surface temperature of the fixing roller. Means for detecting temperature in the fixing device main body, fixing control means for correcting and controlling the set temperature based on the detection result of the environmental temperature detecting means, and mode switching means including a double-sided copy mode And the fixing control means has a plurality of temperature control functions for correcting the set temperature in accordance with the environmental temperature. In the double-sided copy mode, the first-side copying and the second-side copying are performed. The above temperature control function is different and the continuous copy 2 Face copy Time And depending on how many Depending on how long you stay on the duplex tray The temperature control function is different.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a schematic configuration of a color copying machine as an embodiment of an image forming apparatus according to the present invention.
In FIG. 1, the color copying machine supplies a printer 1 for forming a color image based on an electrophotographic process sequence, a scanner 2 for scanning an original and transferring image data to the printer 1, and transfer paper to the printer 1. A bank 3 as a paper feeding device, a document feeding device (DF) 4 for feeding a document to the scanner 2, and a sorter as a post-processing device for sorting transfer paper discharged from the printer 1 5
[0015]
FIG. 2 is a block diagram showing an example of the control configuration of the entire color copying machine 10. The control configuration of the entire color copying machine 10 includes a printer control unit 100, a scanner control unit 200, a bank control unit 300, and DF control. Unit 400, sorter control unit 500, system control unit 800, and operation control unit 900.
[0016]
The printer control unit 100 controls the electrophotographic process sequence and the paper conveyance process. The printer control unit 100 is serially connected to the bank control unit 300 and the sorter control unit 500 via an optical fiber, and performs control according to the image forming timing by a command.
[0017]
The scanner control unit 200 performs document reading control and image processing control of the read image data. The scanner control unit 2 is serially connected to the DF control unit 400 via an optical fiber, and controls the document supply sequence using commands.
[0018]
A system control unit 800 controls the entire system of the present invention. The system control unit 800 passes image forming conditions to the printer control unit 100 and the scanner control unit 200 according to designation from the operation unit 900, manages and controls the state of the entire system, and issues a display command. The system control unit 800 is connected to the printer control unit 100, the scanner control unit 200, the bank control unit 300, the DF control unit 400, the sorter control unit 500, and the operation control unit 900 through optical fibers.
[0019]
In addition, the printer controller 100 and the scanner controller 200 are connected by an optical fiber so that direct sequence control can be performed in order to satisfy the strict accuracy requirements required for alignment during image superposition and registration between transfer paper and image. Has been. Furthermore, a data bus for directly transferring image data from the scanner control unit 200 to the printer control unit 100 is provided.
[0020]
FIG. 3 is a block diagram showing an example of the configuration of the printer control unit 100 of the present invention. Symbol 101 is a CPU for calculating and executing program contents, 102 is a ROM incorporating a control program, and 103 is for storing and saving data. RAMs, which are connected by a data bus and an address bus, respectively.
A serial communication controller 104 transmits and receives commands to and from each control unit, and is connected to the CPU 101 by a data bus and an address bus.
[0021]
Reference numeral 105 denotes a writing control IC that performs exposure control of image data, and is connected to the CPU 101 by a data bus and an address bus. The writing control IC 105 is connected to the LD control unit 106 for exposure and the polygon motor 115 for control.
Reference numeral 107 denotes an I / O controller that performs input / output control.
[0022]
A fixing control device 160 performs PWM output for controlling the fixing heater based on the input value of the fixing thermistor A / D. The fixing controller 160 is connected to a roller temperature sensor 162 that detects the temperature of the fixing roller, an environmental temperature sensor 163 that detects the environmental temperature of the fixing device, and a mode switching unit 161 provided on the operation panel.
Reference numeral 170 denotes a power pack unit, which controls the power pack output by PWM based on the feedback A / D input from the power pack. Further, the output of the power pack unit includes outputs of a charging charger, a charging grid, a developing DC bias, a belt transfer charger, and a paper transfer charger.
[0023]
Reference numeral 180 denotes an electrometer circuit for measuring the surface potential of the photosensitive member.
Reference numeral 181 denotes a P sensor circuit for measuring the toner adhesion amount on the photoconductor. The phototransistor output of the P sensor circuit 181 is an A / D input of the CPU 101, and the PWM output from the CPU 101 is an LED of the P sensor 181. To the driving circuit.
[0024]
110 is a main motor for driving the paper conveying system, 111 is a drum motor for driving the photosensitive member and the intermediate transfer belt, and 112 is a developing motor for driving the developing sleeve. The CPU 101 is supplied with a lock detection signal for determining that the half-speed signal and the speed have reached the target speed.
[0025]
Reference numeral 113 denotes a revolver motor for rotating a revolver equipped with a developing unit, and a four-phase output is output from the CPU 101 so that the revolver of a specified developing color can be stopped at the developing position.
Reference numeral 114 denotes a replenishing motor for replenishing toner from the toner cartridge into the developing unit, and the on-time is controlled in accordance with the toner adhesion amount.
[0026]
Reference numeral 150 denotes an intermediate transfer belt mark sensor which serves as a reference for alignment at the time of color superimposition, and the signal is connected to an interrupt input of the CPU 101 because strict accuracy is required in terms of timing.
Reference numeral 151 denotes a revolver home position (revolver P) sensor that serves as a revolver stop position reference, and the signal is connected to the interrupt input of the CPU 101 because it requires a strict accuracy in terms of timing to switch the output pulse during revolver rotation. .
[0027]
FIG. 4 is a diagram showing an example of input / output devices connected to the I / O controller 107. As output devices, there are a registration clutch (registration CL) 130, a manual feed CL131, a manual pickup solenoid 132, a static elimination lamp 133, an intermediate There are a transfer belt cleaning contact / separation solenoid 134 and a lubricant application solenoid 135, and input devices include a registration sensor 140, a manual paper end sensor 141, a black cartridge sensor 142, a color cartridge sensor 143, a door switch input 144, and a paper discharge sensor 145. There is.
[0028]
FIG. 5 is a cross-sectional view showing the construction of the main part of one embodiment of the printer of the present invention. Symbol 10 is a photoconductor, 20 is a revolver unit, 30 is an intermediate transfer belt, and 40 is a writing system unit.
[0029]
Around the photoreceptor 10, a static elimination lamp (hereinafter referred to as QL) 11, a charged scorotron charger (hereinafter referred to as charging CH) 12, an electrometer 13, a P sensor 14, a pre-transfer static elimination lamp (hereinafter referred to as PTL) 15, a belt transfer charger. 16 and a drum cleaning 17 are provided.
[0030]
The development position of the revolver unit 20 is positioned between the electrometer 13 and the P sensor 14 on the photoreceptor 10, and in the revolver unit 20, black (K), cyan (S), magenta (M), yellow (Y) four-color developing devices 21, 22, 23, and 24 are provided, and the revolver motor 113 is rotated by a four-phase output instruction signal from the CPU 101 to stop the developing device for the specified developing color at the developing position. Let
[0031]
The writing unit 40 includes an LD and a polygon mirror that is rotated by a polygon motor 115, and is disposed between the charging CH 12 of the photoreceptor 10 and the electrometer 13.
[0032]
Around the intermediate transfer belt 30, a belt mark sensor (hereinafter referred to as a mark sensor) 150 for reading a mark provided on the inner side of the belt, which serves as a reference for alignment in the rotational direction from the belt transfer charger 16, is provided. A lubricant application unit 32 for applying lubricant to the transfer belt 30 and a paper transfer charger 33 for transferring the image transferred on the intermediate transfer belt 30 to the transfer paper are provided at the bottom. A belt cleaning unit 34 for cleaning untransferred toner and remaining toner on the intermediate transfer belt 30 is provided between the paper transfer charger 33 and the belt transfer charger 16. Further, the peripheral length of the intermediate transfer belt 30 is longer than the length obtained by adding the maximum image size and the P sensor pattern area (including the distance from the image rear end and the pattern margin length).
The photosensitive member 10 and the intermediate transfer belt 30 are driven by a drum motor 111.
[0033]
The belt cleaning unit 34 can be brought into contact with and separated from the intermediate transfer belt 30 by an intermediate belt cleaning solenoid 134, and the lubricant can be applied by a lubricant application solenoid 135.
[0034]
Further, a registration roller 50 is provided upstream of the paper transfer charger 33 in the paper conveyance path, a conveyance belt 51 is provided on the downstream side, and a fixing unit 52 is provided at the end thereof. The registration roller 50, the conveyance belt 51, and the fixing roller are driven by the main motor 110, and the registration roller 50 is turned on / off by the registration CL130.
[0035]
An example of a main sequence of the printer 1 of the image forming apparatus of the present invention will be described below with reference to FIG.
In the stopped state, the revolver unit 20 is stopped at the position of the development color K (black).
[0036]
<Single color printing sequence>
FIG. 6 is a timing chart of a single color sequence. In the case of single color printing, when a start command is issued from the system control unit 800, the QL 11 and the drum motor 111 are turned on, and the start position of the QL 11 on the photoconductor 10 is set to the charging position. When it reaches, the charging CH12 is turned on. Further, when the position where the charging CH12 is turned on on the photoconductor 10 reaches the developing position, the developing bias (DC + AC) and the developing motor 112 are turned on. Further, when the developing bias position on the photoreceptor 10 reaches the belt transfer position, the belt transfer charger 16 is turned on (the above is the pre-rotation).
If the development position stop color at the time of stop is different from the designated development color, the revolver unit 20 is rotated until the designated development color arrives after the development bias is turned on (in this case, this is the previous rotation).
[0037]
If the exposure position on the photoconductor 10 is charged, a latent image can be formed on the photoconductor 10. At the timing transition, the printer control unit 100 transmits a lamp-on and scanner start instruction signal to the scanner control unit 200 so as to send image data from the scanner 2.
[0038]
When the scanner 2 scans a document, the photoelectrically converted image data is sent to the writing control unit 105 via the scanner control unit 200, and is converted into exposure data by the writing control unit 105. Exposure is performed to form an electrostatic latent image on the substrate 10.
The electrostatic latent image on the photoconductor 10 is developed by a developing device and transferred to an intermediate transfer belt by applying a belt transfer charger.
[0039]
Then, immediately before reaching the paper transfer position, the paper transfer charger 33 is turned on to transfer the image onto the transfer paper. Note that the transfer paper is fed in time for the paper transfer timing, and after the transfer paper tip is abutted against the register roller 50 and enters a standby state, at the timing when the front end of the image and the transfer paper meet at the paper transfer position, The resist CL 130 is turned on.
[0040]
The transfer paper on which the image has been transferred is conveyed to the fixing unit 52 by the conveying belt 51, is thermally fixed by the fixing roller, and is discharged to a paper discharge tray (not shown).
When it is detected that there is no next image formation when the paper transfer is completed, the process proceeds to an end sequence. Specifically, the charging CH12 is turned off when the belt transfer CH16 off position reaches the charging CH12 position, and the developing bias and the developing motor 112 are turned off when the position reaches the developing position. From this point of time, the mark sensor 150 enters the reference mark detection standby state. After the mark detection, the drum motor 111 is turned on until the reference mark is stopped at a predetermined position, and the QL 11 is turned off simultaneously with the drum motor 111 being turned off.
[0041]
<Overlapping color printing sequence>
A full color basic sequence of A4 size (when it is short in the paper transport direction) will be described as an example at the time of color superimposition (the sequence up to the previous rotation is the same as in the case of the above-described single color printing, so the sequence after the previous transition) Describe). 7 and 8 are timing charts of the overlapping color sequence.
[0042]
When the mark sensor 150 detects the reference mark by the rotation of the intermediate transfer transfer belt 30, the mark sensor 150 is connected to the interrupt terminal of the CPU 101. Therefore, an interrupt process is performed on the program, and the first color ( K) scan start command is transmitted.
[0043]
When the electrostatic latent image of the first color (K) on the photoconductor 10 is developed and the belt transfer is completed, the revolver is rotated so that the developing device 22 of the second color (C) comes to the development position.
When the belt transfer is completed, the belt cleaning 34 that has been in contact with the intermediate transfer belt 30 until then is released so that the image on the intermediate belt 30 is not erased. Thereafter, when the mark sensor 150 interrupts detection of the reference mark again, a scan start command for the second color (C) is transmitted.
[0044]
Similarly to the first color, the second color (C) electrostatic latent image is developed, an untransferred image is superimposed on the intermediate belt 30, and when the belt transfer is completed, the third color (M) developing unit 23 is moved to the development position. Rotate the revolver so that
Similarly, for the third color (M) and the fourth color (Y), images are superimposed on the intermediate transfer belt. The full-color image on the intermediate transfer belt 30 that has been belt-transferred is transferred to the transfer paper by turning on the paper transfer charger 33 immediately before reaching the paper transfer position for transfer onto the transfer paper. The paper transfer is the same as in the case of a single color.
[0045]
When the belt transfer for the fourth color (Y) is completed, the revolver unit 20 prepares for repeat by rotating the revolver so that the developing device 21 for the first color (K) comes to the development position. At the same time, the belt cleaning 34 is also brought into the contact state from the released state to clean the transfer residual toner after the paper transfer on the intermediate belt 30 to prepare for the next image formation. Note that the end sequence is the same as that for a single color.
[0046]
FIG. 7 is a timing chart for A4 size (short in the paper conveyance direction), and FIG. 8 is a timing chart for A3 size (long in the paper conveyance direction). In FIG. However, in FIG. 8, the image forming period of one color is between two periods.
[0047]
In the embodiment of the present invention, the next mark timing has already come when the belt transfer is completed at the A3 size. This is because there is no timing for switching to the next development color in one week of the intermediate transfer belt 30. Therefore, the mark detection of the mark sensor 150 is skipped once for each color.
[0048]
Further, the timing relationship between the contact of the belt cleaning 34 and the paper transfer is different between A4 and A3. In the case of A4, since the entire image enters from the position of the belt transfer CH16 to the position of the paper transfer charger 33, the belt cleaning 34 is in contact with the timing before the paper transfer, but in the case of A4, the belt transfer CH16. All the images do not enter from the position to the position of the paper transfer charger 33, and contact is made after paper transfer in order to avoid transfer failure due to contact vibration during paper transfer. In the timing charts of FIGS. 6 to 8, “FGATE” means a gate signal of image data, and the image data is written on the photoconductor 10 while it is on.
[0049]
In the above description, the copying sequence has been described using a copying machine as an example. However, regarding image formation, a scanning start command is not issued to the scanner 2 as an output device that outputs image data from the outside. A desired transfer paper output can be obtained by outputting image data using the mark detection of the mark sensor 150 as a trigger at the time of superposition.
[0050]
FIG. 9 is a block diagram showing the configuration of one embodiment of the fixing heater control unit according to the present invention. Note that FIG. 9 illustrates the case where one heater is used, and the description follows this case. However, when two heaters are used, two heaters having the same configuration may be arranged. The heater is different between the fixing roller and the pressure roller.
[0051]
In FIG. 9, based on the A / D conversion input value of the thermistor signal of each roller, the CPU 101 outputs the on / off signal of the heater 91 by PWM. In the on / off control mode, PWM output is not performed, but the CPU 101 can switch the output. The heater-on signal drives the heater via an SSR (solid state relay) 92.
[0052]
<Fixing temperature control>
Tful and Tother in FIG. 10 indicate temperature control functions (straight lines) corrected under different correction conditions during full color mode operation and during other mode operations. Tful is a temperature control function during full color mode operation, and is controlled by correcting the maximum correction amount ΔTful = 20 deg according to the environmental temperature.
Further, Tother is a temperature control function (straight line) at the time of operation in other modes except full color, and is controlled by correcting the maximum correction amount ΔTother = 16 deg according to the environmental temperature.
[0053]
FIG. 11 shows the temperature control function during full color mode operation out of the temperature control functions shown in FIG. 10, and the vertical axis (temperature) is enlarged.
In a full-color image forming apparatus that controls and controls the set temperature under different correction conditions in the conventional full-color mode operation and in other mode operations, when the temperature of the fixing roller is corrected by the environmental temperature, for example, the temperature is low Even if the transfer paper temperature is low in the environment, if the second side is copied as it is, it will cause a problem of excessive heat, hot offset, or high glossiness. I had to do it.
[0054]
Therefore, in the present invention, when duplex copying is performed, for example, as shown in FIG. 10, the temperature control function for copying the first side in the full color mode is Tful, and the temperature control function for copying the second side is T ′. ful, the temperature control function at the time of the first surface operation in another mode is different from Tother, and the temperature control function at the time of the second surface operation is different from T'other. The correction amount is also the first color maximum correction amount ΔTful = 20 deg in the full color mode, the second surface maximum correction amount ΔT′ful = 15 deg, the first surface maximum correction amount ΔTother = 16 deg in the other mode, and the second surface maximum correction amount ΔT′other = 10 deg. That is how they differ. Thus, by correcting and controlling under the correction conditions different from those in the normal mode (first surface), it is possible to prevent problems such as excessive heat amount and hot offset.
[0055]
In FIG. 10, the control temperature during the second-side copy operation is set to be equal to or lower than the control temperature during the first-side copy operation. That is,
T'ful ≦ Tful
T'other ≦ Tother
The relationship is established. This is because in the case of the second-side copy, the temperature of the transfer paper is increased by the first-side copy, so the temperature of the fixing roller is lowered to prevent excessive heat.
[0056]
Further, in FIG. 10, the correction amount during the second-side copy operation is set to be equal to or less than the correction amount during the first-side copy operation. That is,
ΔT'ful ≦ ΔTful
ΔT'other ≦ ΔTother
The relationship is established. In the case of copying on the second side, since the temperature of the transfer paper is higher than that on the first side, the amount of heat received from the periphery is reduced even if the environmental temperature is increased, and the fixing roller is used even when the environmental temperature is high. This is because the temperature cannot be lowered and the correction amount decreases.
[0057]
FIG. 11 shows an embodiment in which the temperature control functions are made different in consideration of changes in the transfer paper temperature from the first side copy to the second side copy.
A color image forming apparatus having a single photoconductor requires a lot of time for duplex copying. For example, consider a case where 50 double-sided copies are taken from the same document. In this case, double-sided copying is performed by continuously copying only the first side of the transfer paper from the first to the 50th and stocking them on the double-sided tray. Next, copying of the second page is continuously performed in the reverse direction from the 50th sheet to the first sheet. Then, the 50th transfer sheet stays in the duplex tray only for a short time, but from the 49th sheet, the transfer paper stays in the duplex tray gradually, and the first sheet stays for the longest time. . As the time during which the transfer paper stays on the double-sided tray becomes longer, the temperature of the transfer paper also decreases. That is, the temperature of the transfer paper at the time of copying on the second side is different between the 50th sheet and the first sheet. Therefore, in the temperature control function shown in FIG. 10, there is a possibility that a defective fixing due to a shortage of heat occurs in the transfer paper whose temperature is lowered.
[0058]
Therefore, in the present invention, as shown in FIG. 11, when the second side is copied in the full color mode, the first (50th) temperature control function is T′ful1, and the tenth temperature control function is T ′ Ful10, the 50th (first) temperature control function is T′ful50, the first maximum correction amount on the second side in the full color mode is ΔT′ful1 = 15 deg, and the tenth maximum correction amount is ΔT Control is performed by changing the temperature control function for each sheet so that ′ ful10 = 15.5 deg and the 50th maximum correction amount is ΔT′ful50 = 17.5 deg. In this way, by performing an appropriate temperature correction for each number of sheets, it is possible to prevent insufficient heat and excessive heat and improve image quality.
[0059]
In the above example, the copy on the second side is copied from the 50th sheet to the first sheet, but a copy of the second page is copied from the first sheet to the 50th sheet. In such a case, the time for which each transfer paper stays on the double-sided tray is almost the same, but there is a difference between what is near the surface of the double-sided tray and what is inside, and gradually from the first sheet to the 50th sheet. In some cases, a temperature difference may occur, and as shown in FIG. 11, the image quality can be improved by changing the temperature control function for each sheet.
[0060]
<Pressure roller temperature control>
In a fixing device of a general full color image forming apparatus, a heating unit and a surface temperature detecting unit are also provided in the pressure roller in order to perform fine temperature control. Therefore, finer temperature control can be performed by controlling the pressure roller in the same manner as the fixing roller.
[0061]
Further, since the pressure roller is generally in contact with the back surface of the transfer paper, it requires less heat than the fixing roller. Therefore, it is desirable that the correction amount of the pressure roller during the operation of the second side in double-sided copying is not more than the correction amount of the first side. Further, it is desirable that the temperature of the pressure roller during the operation of the second surface is equal to or lower than the temperature of the first surface. Furthermore, a temperature control function can be created for various modes, and a function to be used can be determined according to switching of each mode.
[0062]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, in the double-sided copy mode, the temperature control function of the fixing roller is made different between the first-side copy and the second-side copy. Even if changes, a copy with good image quality can be obtained on both sides.
[0063]
In addition, copy on both sides -In the mode, depending on the number of sheets in the second side copy, depending on how long it stays in the duplex tray Change the temperature control function on the second side Because Even when the second side is copied using a transfer sheet that has been stacked on the double-sided tray for a long time and the surface temperature is lowered, fixing failure due to insufficient heat can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a color copying machine as an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a block diagram illustrating a control configuration example of the entire color copying machine.
FIG. 3 is a block diagram illustrating a configuration example of a printer control unit according to the present invention.
FIG. 4 is a diagram illustrating an example of input / output devices connected to an I / O controller.
FIG. 5 is a side view showing a configuration of a main part of one embodiment of the printer of the present invention.
FIG. 6 is a timing chart of a single color sequence.
FIG. 7 is a timing chart in the case of A4 size.
FIG. 8 is a timing chart in the case of A3 size.
FIG. 9 is a block diagram showing a configuration of one embodiment of a fixing heater control unit according to the present invention.
FIG. 10 is a diagram showing an example of a temperature control function in the full color mode and other modes.
FIG. 11 is a diagram showing an example in which the temperature control function is made different depending on the number of double-sided copies.
[Explanation of symbols]
160 Fixing unit (fixing roller, pressure roller)
161 Mode switching means
162 Roller temperature detection means
163 Environmental temperature detection means
800 System control unit (control means)
Temperature control function for the first side of Tful full color and duplex copy mode
Temperature control function for the second side of T'ful full color and duplex copy mode
Tother Temperature control function for the first side of duplex copying in other modes
T'other Temperature control function for the second side of duplex copying in other modes
ΔTful Maximum correction amount for the first side of duplex copy mode in full color mode
ΔT'ful Maximum correction amount on the second side (correction amount)
ΔTother Maximum correction amount (correction amount) on the first side of other modes
ΔT'other Maximum correction amount on the second side of other modes (correction amount

Claims (1)

A fixing roller that is controlled so that the surface temperature becomes a preset temperature, roller temperature detecting means for detecting the surface temperature of the fixing roller, environmental temperature detecting means for detecting the temperature in the fixing device body, and the environment A fixing control unit configured to correct and control the set temperature based on a detection result of the temperature detection unit; and a mode switching unit including a double-sided copy mode. The fixing control unit corrects the set temperature according to an environmental temperature. a plurality of temperature control function for, in the case of double-sided copy mode, is different from the temperature control function in a time first side copies and the time of the second side copying, and to have contact at the second surface copying when continuous copying A fixing device for an image forming apparatus, wherein the temperature control function is made different according to the time of staying in the double-sided tray depending on the number of sheets.

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