JP2005055527A - Fixing device and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve imbalance (temperature distribution non-uniformity) of a temperature of a fixing device at the time of printing operation and to reduce a rush current with paper in progress. <P>SOLUTION: The device is equipped with a heating roller 231, a main heater 232a and sub heater 232b for heating the heating roller 231, a main thermistor 233a and sub thermistor 233b and a fixing drive section 237 for heating and controlling the heating roller 231 by individually driving the main heater 232a and the sub heater 232b based on detected temperatures of the thermistors 233a and 233b, and when the fixing device is in warm up operation, the fixing drive section 237 drives both of the heaters 232a and 232b until the temperature of the heating roller 231 reaches a print start temperature and when the detected temperature of either of the thermistors 233a or 233b reaches the print start temperature, driving of the heater of which the temperature is reached to is stopped and afterwards, the temperature adjusting at the time of the printing operation is performed by the other heater. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heating control method for efficiently controlling heating of a fixing device mounted on an image forming apparatus such as a copying machine, a printer device, or a facsimile device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in image forming apparatuses such as copiers, printer apparatuses, and facsimile apparatuses, fixing is performed by fixing a toner image on a sheet by sandwiching and conveying the sheet on which the toner image is transferred between roller members. Equipment. In this fixing device, at least one of a pair of roller members arranged to face each other is provided with a heating unit that heats a predetermined range of the sheet to a fixing temperature, and power supply to the heating unit is switched ON or OFF. Thus, the fixing device (one roller member) is controlled within a desired fixing temperature range.
[0003]
For such heating control of the fixing device, various methods have been proposed from the viewpoint of low power / fast heat.
[0004]
For example, the heating roller is provided with a main heater with high power consumption and a sub-heater with low power consumption, and within the printable temperature range, the fixing set temperature and the judgment reference temperature are set, and when printing is performed, If the temperature of the heating roller is lower than the reference temperature, drive the main heater with high power consumption to shorten the fixing start-up time. If the temperature of the heating roller is higher than the reference temperature A technique has been proposed in which a sub-heater with low power consumption is driven to measure low power consumption (see, for example, Patent Document 1).
[0005]
In addition, a drive start temperature and a drive stop temperature are set for each of the main heater and the sub heater, and what position the temperature detected at the same point is relative to the set temperature described above, and what A technique has been proposed in which the life of the heater lamp is extended and the rush current is reduced by determining whether the temperature is changing and driving the main heater and the sub heater alternately (for example, Patent Documents). 2).
[0006]
[Patent Document 1]
JP-A-11-65359
[Patent Document 2]
Japanese Patent Laid-Open No. 9-16015
[0007]
[Problems to be solved by the invention]
However, in the two heating control systems shown in the above prior art, it is difficult to keep the temperature distribution on the heating roller uniform when driving the two heater lamps. There is a problem that there is a large possibility of causing temperature imbalance near the center and side of the heating roller.
[0008]
The present invention was devised to solve such problems, and its purpose is to solve such temperature imbalance (temperature distribution non-uniformity) and to reduce the rush current during sheet passing. An object of the present invention is to provide a fixing device that can be used and an image forming apparatus including the same.
[0009]
[Means for Solving the Problems]
The fixing device of the present invention includes a heating roller, a first heating unit and a second heating unit that heat the heating roller, a first temperature detection unit that detects a temperature of a portion heated by the first heating unit, A second temperature detecting means for detecting the temperature of the portion heated by the second heating means; and the first heating means and the second heating means are individually set based on the detected temperatures of the first and second temperature detecting means. In a fixing device having a control means for driving and controlling the heating roller to heat, the heating roller is heated and controlled from turning on the power until it becomes ready for printing or until it becomes ready for printing from the standby state. During operation, the control means drives both the heating means until the heating roller is raised to the printing start temperature, and detects either of the first temperature detection means or the second temperature detection means. When degree reaches the print start temperature, the drive of the heating means towards reaching stopped, thereafter is characterized in that the temperature adjustment operation so as to control temperature during the printing operation by the other of the heating means.
[0010]
Here, the first heating means is composed of a main heater that preferentially heats the vicinity of the central portion in the width direction of the heating roller, and the second heating means is preferentially near both ends in the width direction of the heating roller. It consists of a sub-heater that heats.
[0011]
That is, in the present invention, the main heating portion on the heating roller where the main heater as the first heating means and the sub-heater as the second heating means are preferentially heated so that the temperature distribution of the heating roller does not become uneven. In addition, independent thermistors (first temperature detecting means and second temperature detecting means) are provided. Then, by determining the drive switching timing of the heating means based on the temperature relationship detected by the plurality of thermistors, a fixing device in which the temperature distribution of the heating roller is uniform and the rush current is reduced is realized. ing.
[0012]
Further, according to the present invention, after the warm-up operation is completed, the control unit performs heating when the temperature of the heating unit that has stopped driving at the end of the warm-up operation falls below the lower limit value of the printable temperature range. While the driving of the means is started, the driving of the heating means that has been driven so far is stopped at that time, and thereafter, the temperature adjusting operation is performed by the heating means that has started driving. In this way, while maintaining the uniformity of the temperature distribution of the heater lamp, only one of the main heater and the sub-heater is driven after the warm-up operation is completed, so that power consumption during the printing operation can be reduced.
[0013]
Further, according to the present invention, the control unit starts driving the heating unit and stops driving the other heating unit each time the temperature of the heating unit that has stopped driving falls below the lower limit value of the printable temperature range. To repeat the temperature control operation. After the warm-up operation is completed, the printing operation can be continued in a low power consumption state while maintaining the uniformity of the temperature distribution of the heater lamp by alternately repeating the driving and stopping of the two heating means. .
[0014]
According to the present invention, when printing is started, the control means sets a temperature that is below a temperature range in which either one or both of the first temperature detection means and the second temperature detection means can be printed. If detected, both the first heating means and the second heating means are driven, the driving of the heating means that has reached the print start temperature first is stopped, and the other heating means controls the control temperature during the printing operation. When the printing operation is started after reaching the temperature of the first temperature detection means, while the first temperature detection means or the second temperature detection means both detect the temperature within the printable temperature range, the first and second temperature detection means It is characterized in that the printing operation is started immediately while performing the temperature adjustment operation so that the control temperature at the time of the printing operation is achieved by the heating device showing the low temperature among the second temperature detection means.
[0015]
According to the present invention having such characteristics, when printing is started, if the heating roller is below the printable temperature range, both the first heating means and the second heating means are driven. Thus, the time until the start of printing can be shortened. In addition, when printing is started, if the heating roller is within a printable temperature range, the printing operation can be started immediately after cutting off excess power.
[0016]
Further, according to the present invention, the print start temperature is set to a temperature lower than the control temperature during the printing operation within the printable temperature range. Thereby, it is possible to prevent an overshoot such that the temperature rises excessively with respect to the control temperature during the printing operation, and the printing operation can be controlled safely.
[0017]
The image forming apparatus of the present invention further includes a fixing device having the above-described configuration, and further includes a sheet conveying unit that conveys the sheet to the image forming area. The control unit includes the first heating unit and the first heating unit. The driving of the paper conveying means is stopped while both the two heating means are driven, and the paper conveying means is driven when either the first heating means or the second heating means is driven. It is characterized by doing. Thus, during the warm-up period in which both the first and second heating means are driven, the power for paper conveyance and the like is stopped, thereby driving the first heating means, the second heating means, and the paper. The power required for driving the conveying means does not overlap, and the maximum operating power of an image forming apparatus such as a copying machine can be reduced.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a schematic configuration diagram showing the inside of an image forming apparatus provided with a fixing device of the present invention.
[0020]
The image forming apparatus 1 is of a multi-functional type and has functions as a copying machine, a printing machine, and a facsimile machine. The image forming apparatus 1 includes a printer 2, a scanner 3, an automatic document feeder 4, a paper discharge processing device 5, and a multistage paper feeding device 6. Hereinafter, the configuration of each unit will be described.
[0021]
The automatic document conveying device 4 includes a document conveying mechanism 41 as a power consuming device, conveys and positions the document placed on the document setting tray 40 on the platen glass 30, and reads an image by the scanner 3. The original is conveyed to the original discharge tray 42 and discharged. Further, one side of the automatic document feeder 4 (one side on the back side in FIG. 1) is pivotally supported so that an unconveyable document can be placed on the platen glass 30, and the entire device 4 can be opened and closed. ing.
[0022]
The scanner 3 can select and set either the automatic reading mode or the manual operation reading mode. When the former automatic reading mode is selected, the scanner 3 reads an image of the original in conjunction with the conveyance of the original onto the platen glass 30 by the automatic original conveying device 4. When the latter manual operation reading mode is selected, the scanner 3 reads the image of the document placed on the platen glass 30 in response to the manual operation. In any mode, the first and second scanning units 31 and 32 as the power consuming devices are moved while maintaining a predetermined speed relationship with each other, and the image of the document placed on the platen glass 30 is moved to the first. Exposure is performed by one scanning unit 31, reflected light from the document is guided to the lens 33 by the first and second scanning units 31, 32, and an image of the document is formed on the photoelectric conversion element (CCD) 34 by the lens 33. . The CCD 34 scans and reads an original image repeatedly in the main scanning direction, and outputs image data based on the original image. The scanner 3 is configured to attach the type of recording paper based on the image data based on the original image.
[0023]
The printer 2 inputs image data from the scanner 3 and image data from an external device (for example, a personal computer), and records an image indicated by the image data on a recording sheet.
[0024]
The printer control unit 24 provided in the printer 2 serves as an interface for controlling the electrophotographic process unit 20 and receiving image data from an external device. The image control unit 25 performs predetermined image processing on the image data from the external device, and drives and controls the optical scanning unit 22 as a power consuming device according to the image data.
[0025]
The electrophotographic process unit 20 includes a photosensitive drum 200, a charging roller 201, an optical scanning unit 22, a developing unit 202, a transfer unit 203, a cleaning unit 204, a charge removal unit (not shown), and the like. The photosensitive drum 200 is rotated in one direction by a drum motor (power consumption device) (not shown). The charging roller 201 uniformly charges the surface of the photosensitive drum 200. The optical scanning unit 22 forms a light beam (light image) modulated according to image data, and repeatedly scans the surface of the photosensitive drum 200 in the main scanning direction with the light beam, and electrostatically scans the surface of the photosensitive drum 200. A latent image is formed. The developing unit 202 supplies toner to the surface of the photoreceptor 200. The toner adheres to the electrostatic latent image on the surface of the photosensitive drum 200, and a toner image is formed. The transfer unit 203 superimposes the recording sheet conveyed from below and the photosensitive drum 200, and transfers the toner image from the photosensitive drum 200 to the recording sheet. The cleaning unit 204 removes toner remaining on the surface of the photosensitive drum 200. The static elimination unit removes electric charges on the surface of the photosensitive drum 200.
[0026]
A fixing device 23 is disposed above the electrophotographic process unit 20. The fixing device 23 heats and pressurizes the recording paper to fix the toner image on the recording paper. The recording sheet on which the toner image has been fixed is conveyed by each discharge roller 28 as a power consuming device, and delivered to the relay path unit 8 as the power consuming device of the paper discharge processing device 5.
[0027]
When recording an image on the back side of the recording sheet, the conveyance of the recording sheet is temporarily stopped and the recording sheet is conveyed from the relay path unit 8 to the printer 2 in the reverse direction. In the printer 2, the branching claw 251 is rotated, the recording paper is guided to the reversing conveyance path 250 by the branching claw 251, and the recording paper is conveyed again to the electrophotographic process 20 through the reversing conveyance path 250. The image is recorded on the back side of the recording paper by inverting the front and back of the paper. The recording paper on which the images are recorded in this way is conveyed by each discharge roller 28 and delivered to the relay path unit 8 of the paper discharge processing device 5.
[0028]
In addition, a paper feeding unit 21 is provided at the bottom of the printer 2. The sheet feeding unit 21 stacks and stores recording sheets, and separates and removes the recording sheets one by one from the sheet storing cassette 210 and supplies the recording sheets to the electrophotographic process unit 20. And a take-out unit 211 as an electric power game device. The recording sheet taken out by the take-out unit 211 is conveyed to the transfer unit 203 and further conveyed by the discharge rollers 28 via the fixing device 23. This recording sheet is conveyed with a center reference that is aligned with respect to the center perpendicular to the conveying direction with respect to the center of the fixing device 23 (the center in the axial direction of a heating roller 231 described later). The paper storage cassette 210 can be pulled out from the main body of the image forming apparatus, and the recording paper can be supplied to the paper storage cassette 210 in the pulled-out state.
[0029]
The paper discharge processing apparatus 5 is an option and is detachable from the image forming apparatus 1 and includes a relay path unit 8 and a post-processing unit 9.
[0030]
The relay path unit 8 receives a recording sheet from the printer 2 and conveys the recording sheet to the post-processing unit 9 and a switchback that temporarily receives the recording sheet from the printer 2 and returns the recording sheet to the printer 2. A path 83 and a gate plate 81 for guiding the recording sheet from the printer 2 to either the relay path 84 or the switchback path 83 are provided. The gate plate 81 is swingable. When the leading end is directed upward, the recording sheet is guided to the relay path 84, and when the leading end is directed downward, the recording sheet is guided to the switchback path 83. .
[0031]
The relay path 84 is provided with a conveyance roller 85 that rotates in one direction, and the conveyance roller 85 guides the recording sheet to the post-processing unit 9. Further, the switchback path 83 is provided with a placement plate 86 on which recording paper is placed and a transport roller 87 that can rotate forward and backward. Not only the transport roller 87 but also the transport rollers 28 of the printer 2 can rotate forward and backward. When the recording sheet is led to the switchback path 83, the rear end of the recording sheet is sandwiched between the conveying rollers 28 of the printer 2, and the conveying rollers 87 and 28 are set with the recording sheet placed on the mounting plate 86. Stop and temporarily stop the conveyance of the recording paper. Thereafter, the transport rollers 87 and 28 are rotated in reverse to transport the recording paper to the printer 2 in the reverse direction. In the printer 2, as described above, the recording paper is guided to the reversal conveyance path 250 by the branching claw 251, and the recording paper is conveyed again to the electrophotographic process 20 through the reversal conveyance path 250. Record an image on
[0032]
The post-processing unit 9 receives the recording paper from the printer 2 through the relay path 84 and performs post-processing on the recording paper. Examples of the post-processing include stapling processing and sorting processing. The recording sheet on which this processing has been performed is discharged to one of the plurality of discharge trays 56 and 59.
[0033]
The printer 2 and the paper discharge processing device 5 are placed on a multi-stage paper supply device 6. The scanner 3 and the automatic document feeder 4 are placed on a system rack 7. At the bottom of the multi-stage sheet feeding device 6, each moving roller 69 and each fixed portion 68 are provided. If each fixing portion 68 is screwed into the bottom of the multi-stage sheet feeding device 6, each fixing portion 68 is separated from the floor surface and the multi-stage feeding device 6 is supported by each moving roller 69, the multi-stage feeding device 6 is moved. be able to. In this state, the multi-stage paper feeding device 6, the printer 2, and the paper discharge processing device 5 are moved and arranged inside the system rack 7. Thereafter, the multi-stage sheet feeding device 6 is fixed by rotating and protruding the fixing portions 68 and bringing the fixing portions 68 into contact with the floor surface. At this time, a space is formed between the relay path unit 8 of the paper discharge processing device 5 and the scanner 3.
[0034]
The multi-stage sheet feeding device 6 is an option and is detachable from the image forming apparatus 1. In the multistage sheet feeding device 6, a plurality of types of recording sheets are stored in the respective sheet storage cassettes 61, 62, 63. In the multi-stage sheet feeding device 6 of the present embodiment, the upper cassette 61 that is positioned above and can accommodate a relatively large size (for example, A3 size) recording sheet, and the lower cassette 61 are juxtaposed. A pair of lower cassettes 62 and 63 capable of accommodating recording sheets having a frequently used size (for example, A4 size) are provided.
[0035]
A paper guide passage 65 extending in the vertical direction is provided inside the multi-stage paper feeding device 6, and the recording paper taken out from each cassette 61, 62, 63 is supplied to the printer 2 through the paper guide passage 65. It has become so. A paper receiving opening 27 is formed on the lower surface of the printer 2 at a position corresponding to the paper guide path 65 so that the recording paper that has passed through the paper guiding path 65 passes through the paper receiving opening 27 and is guided to the printer 2. It has become.
[0036]
A take-out unit 611 is provided on the paper discharge side (left side in the figure) of the upper cassette 61. The take-out unit 611 separates and takes out the recording sheets stored in the upper cassette 61 one by one, and sends the recording sheets to the electrophotographic process unit 20 through the sheet guide passage 65 and the sheet receiving port 27. It has become. Note that the upper cassette 61 can be pulled out from the sheet feeding device frame 66 as the main body of the multi-stage sheet feeding device to the front side in the figure, and recording paper can be replenished in the pulled-out state.
[0037]
Next, the configuration of the fixing device 23, which is a characteristic part of the present invention, will be described with reference to FIGS.
[0038]
As shown in FIG. 2, the fixing device 23 includes a heating roller 231 as a fixing heating body that is a heating member, a halogen heater 232 as a heating unit that heats the heating roller 231, and a drive that rotationally drives the heating roller 231. Means (not shown), a temperature sensor (thermistor) 233 for detecting the temperature of the heating roller 231, and a pressure roller 234 arranged to face the heating roller 231 are provided.
[0039]
The halogen heater 232 is disposed inside the heating roller 231. As shown in FIG. 3, a main heater 232a in which a lamp is disposed at the center in the axial direction in accordance with the center reference of the recording paper, and the main heater. And sub heaters 232b each having lamps arranged on both sides in the axial direction of 232a.
[0040]
In addition, the temperature sensor (thermistor) 233 is arranged such that the main thermistor 233a is disposed at the point where the main heater 232a is preferentially heated and the subthermistor 233b is preferentially heated. 233b is disposed, and the outputs of the thermistors 233a and 233b are guided to the temperature detection unit 236. The temperature detection unit 236 converts the resistance value detected from each of the main thermistor 233a and the sub-thermistor 233b into a temperature, and the output of the temperature detection unit 236 is guided to the fixing drive unit 237. . The fixing driving unit 237 drives the main thermistor 233a and the sub thermistor 233b based on the temperature detected by the temperature detecting unit 236.
[0041]
FIG. 4 shows an electrical configuration of an image forming apparatus provided with the fixing device 23 having such a configuration. However, only the portion related to the present invention is shown here. That is, the output of the temperature detection unit 236 is connected to an engine control unit 2371 that controls the engine based on the detected temperature, and the output of the engine control unit 2371 drives heaters that drive the main thermistor 233a and the sub-thermistor 233b, respectively. The unit 2372 is connected to a sheet conveyance driving unit 238 that conveys a recording sheet for forming an image to an image forming area. Note that the fixing driving unit 237 shown in FIG. 3 corresponds to the engine control unit 2371 and the heater driving unit 2372 in FIG.
[0042]
The main heater 232a and the sub heater 232b are energized through the heater driving unit 2372 based on a command from the engine control unit 2371, thereby emitting light with a predetermined heat generation distribution (central portion and both left and right side portions), and emitting infrared rays. Thus, the inner peripheral surface of the heating roller 231 is heated. The main heater 232a and the sub heater 232b are independently temperature controlled by the engine controller 2371.
[0043]
The heating roller 231 is heated to a control temperature (for example, 200 ° C.) during the printing operation by the main heater 232a and the sub heater 232b, and the nip portion K of the fixing device 23 (the nip portion between the heating roller 231 and the pressure roller 234). The recording paper that is the heated medium passing through K) is heated.
[0044]
Next, an embodiment of drive control of each heater at the start of the printing operation by the fixing device having the above configuration will be described.
[0045]
<Example 1>
The present embodiment is an embodiment of drive control of each heater during a warm-up operation in which the heating roller is heated from the power-on until the printable state is reached or until the printable state is reached from the standby state. Hereinafter, the temperature change of each heater shown in FIG. 5 and the flowchart shown in FIG. 6 will be described.
[0046]
In the first embodiment, both the main heater 232a and the sub heater 232b are driven at the same time (time t1) as the warm-up operation is started when the power is turned on (step S1 to step S3). The engine control unit 2371 monitors whether or not the temperature of the heating roller 231 by driving the main heater 232a or the sub heater 232b has reached the printing start temperature Ts from the time of power ON (step S4). In the example shown in FIG. 5, the temperature of the heating roller 231 reaches the print start temperature Ts earlier than the temperature driven by the sub heater 232b when the temperature is driven by the main heater 232a.
[0047]
Therefore, when the temperature of the heating roller 231 driven by the main heater 232a reaches the printing start temperature Ts (time t2), the engine control unit 2371 stops driving the main heater 232a at that time (step S5). Accordingly, the sub heater 232b thereafter performs a temperature adjustment operation (hereinafter referred to as “temperature control”) so as to reach a control temperature (hereinafter referred to as “printing control temperature”) Tc during the printing operation (step S6). This control state is determined until the temperature of the heating roller 231 driven by the main heater 232a falls below the lower limit value Twl of the printable temperature range (hereinafter referred to as “printable temperature range”) Tw (Yes in step S7). Will continue).
[0048]
When the temperature of the heating roller 231 driven by the main heater 232a falls below the lower limit value Twl (time t3), the sub heater 232b is turned off and the main heater 232a is turned on at the same time (steps S8 and S9). Temperature control is performed by the heater 232a so that the print control temperature Tc is reached (step S10). This control state is continued until time t4 when the temperature of the heating roller 231 driven by the sub heater 232b falls below the lower limit value Twl of the printable temperature range Tw (until determined as Yes in step S11).
[0049]
When the temperature of the heating roller 231 driven by the sub heater 232b falls below the lower limit value Twl (time t4), the sub heater 232b is turned on (step S12) and the main heater 232a is turned off (step S8). Thereafter, the temperature adjustment control is continued by repeating the processing operations in steps S5 to S12.
[0050]
By performing such an operation, the temperature of the heating roller 231 by driving the main heater 232a and the sub heater 232b does not deviate from the printable temperature range Tw, and both the heaters 232a and 232b are driven simultaneously during printing. Therefore, stable printing operation with low power is possible.
[0051]
In the first embodiment, as shown in FIG. 5, the print start temperature Ts, which is the timing to stop one heater (here, the main heater 232a) from the warm-up operation, is lower than the print control temperature Tc. Is set.
[0052]
That is, in the first embodiment, the end point of the warm-up operation period is the time point (time t2) when the main heater 232a reaches the print start temperature Ts, and the main heater 232a is stopped at that timing, but the sub heater 232b continues to be driven. Therefore, also in the vicinity of the center of the heating roller 231 mainly heated by the main heater 232a, overshoot occurs immediately after the main heater 232a stops due to heat transfer from the vicinity of the side of the heating roller 231 continuously heated by the sub heater 232b. It can happen. Therefore, in order to prevent the occurrence of an overshoot, the print start temperature Ts, which is the timing to stop one heater (here, the main heater 232a) from the start of the warm-up operation, is set to the print control. It is effective to set the temperature lower than the temperature Tc.
[0053]
<Example 2>
In the first embodiment, the drive control of each heater from the start of the warm-up operation when the power is turned on has been described. However, in this second embodiment, the heating roller of each heater when there is a print start request. An embodiment of drive control according to the heating state will be described with reference to a flowchart shown in FIG.
[0054]
When a print start request is issued to the image forming apparatus (step S31), the engine control unit 2371 drives the main heater 232a and the sub heater 232b based on the detected temperature based on the detected resistance value of the main thermistors 233a and 233b. The temperature state of each part of the heating roller 231 is confirmed (steps S32 and S33), and it is determined whether or not the temperature of each part of the heating roller 231 is within the printable temperature range Tw.
[0055]
As a result, when one or both of the main thermistor 233a and the sub-thermistor 233b detects a temperature that is lower than the printable temperature range Tw (when No is determined in step S32 or No in step S33), The engine control unit 2371 drives both the main heater 232a and the sub heater 232b (Step S34, Step S35). Thereafter, it is monitored whether the temperature of the heating roller 231 driven by the main heater 232a or the temperature of the heating roller 231 driven by the sub heater 232b has reached the print start temperature Ts (step S36).
[0056]
As a result, when the temperature of the heating roller 231 by driving the sub heater 232b reaches the print start temperature Ts first, the driving of the sub heater 232b is stopped at that time (step S37), and the driving of the main heater 232a is continued as it is. (Step S38). When the temperature of the heating roller 231 driven by the main heater 232a reaches the print control temperature Ts (when determined Yes in step S39), temperature control is performed by driving the main heater 232a to start printing. (Step S40, Step S41).
[0057]
On the other hand, in step S36, when the temperature of the heating roller 231 by driving the main heater 232a first reaches the printing start temperature Ts, the driving of the main heater 232a is stopped at that time (step S42), and the sub heater 232b is turned on. The driving continues as it is (step S43). When the temperature of the heating roller 231 driven by the sub-heater 232b reaches the print control temperature Ts (when determined Yes in step S44), temperature control is performed by driving the sub-heater 232b to start printing (step S45, step S41).
[0058]
On the other hand, when both the main thermistor 233a and the sub-thermistor 233b detect the temperature within the printable temperature range Tw when a print start request is made to the image forming apparatus (Yes in step S32, in step S33). If the determination is Yes), the engine control unit 2371 checks whether the temperature of the heating roller 231 by the main heater 232a or the temperature of the heating roller 231 by the sub heater 232b is lower at that time (step) S46). At this time, both heaters 232a and 232b are in a stopped state.
[0059]
As a result, when the temperature of the heating roller 231 by the main heater 232a is lower, the main heater 232a is driven (step S47), and the temperature of the heating roller 231 by driving the main heater 232a reaches the printing start temperature Ts. At the time (when it is determined Yes in step S49), printing is started (step S41). On the other hand, if the temperature of the heating roller 231 by the sub heater 232b is lower in step S46, the sub heater 232b is driven (step S48), and the temperature of the heating roller 231 by driving the sub heater 232b reaches the printing start temperature Ts. At the time (when it is determined Yes in step S49), printing is started (step S41).
[0060]
As described above, when the print start request is made, the temperature condition of the heating roller 231 by driving the heaters 232a and 232b is confirmed, and by driving the heater optimally according to the state, unnecessary electric power can be generated. Cutting and printing time can be shortened.
[0061]
<Example 3>
Example 3 is an example of a printing operation performed by the image forming apparatus according to the present exemplary embodiment.
[0062]
As shown in FIG. 8, main power types for operating the image forming apparatus include a driving power (700 W) for the main heater 232 a, a driving power (500 W) for the sub-heater 232 b, and a power (200 W) for the paper transport driving unit 238. Is mentioned.
[0063]
When all these powers are added, a total of 1400 W is required. In this embodiment, during the warm-up operation period in which both the main heater 232a and the sub heater 232b are driven, the heating roller 231 Since the fixing temperature does not reach the printable temperature range Tw, the power of the paper conveyance drive unit 238 is stopped. As a result, the total power during the warm-up operation period is 1200 W.
[0064]
In other words, during the warm-up period in which both the main heater 232a and the sub heater 232b are driven, the power of paper conveyance or the like is stopped to drive the main heater 232a, the sub heater 232b, and the paper conveyance drive unit 238. The power required for driving does not overlap, and the maximum operating power of the image forming apparatus can be reduced by 200 W.
[0065]
Then, as in the first and second embodiments, when either the main heater 232a or the sub-heater 232b is driven, the paper conveyance driving unit 238 is driven to perform a printing operation. Thus, the total power during the printing operation is 700 W when the sub heater 232b is driven and 900 W when the main heater 232a is driven.
[0066]
【The invention's effect】
As described above, according to the fixing device of the present invention, during the warm-up operation, by driving both the first heating unit and the second heating unit, the time until the start of printing can be shortened, and the first By detecting the temperatures of both the heating means and the second heating means, it is possible to perform a printing operation while maintaining a uniform temperature distribution.
[0067]
Further, according to the fixing device of the present invention, only one of the first heating unit and the second heating unit is driven after the warm-up operation while maintaining a uniform temperature distribution, so that the printing operation with reduced power consumption is achieved. Is possible.
[0068]
Further, according to the fixing device of the present invention, when printing is started, if the heating roller is below the printable temperature range, both the first heating unit and the second heating unit are driven. , The time to start printing can be shortened. In addition, when printing is started, if the heating roller is within a printable temperature range, the printing operation can be started immediately after cutting off excess power.
[0069]
Further, according to the present invention, the temperature rises with respect to the control temperature during the printing operation by setting the printing start temperature to a temperature lower than the control temperature during the printing operation within the printable temperature range. It is possible to prevent overshooting such as excessively and to control the printing operation safely.
[0070]
Further, according to the image forming apparatus of the present invention, during the warm-up period in which both the first and second heating units are driven, the power of the sheet conveyance or the like is stopped to drive the first heating unit. The power required for driving the second heating unit and the driving of the sheet conveying unit does not overlap, and the maximum operating power of the image forming apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing the inside of an image forming apparatus provided with a fixing device of the present invention.
FIG. 2 is a side view illustrating a schematic configuration of a fixing device.
FIG. 3 is an explanatory diagram showing an arrangement position and electrical configuration of each thermistor on a heating roller.
FIG. 4 is a block diagram showing an electrical configuration of a main part of the image forming apparatus of the present invention.
FIG. 5 is a graph showing a temperature change of a corresponding portion of a heating roller heated by drive control of each heater during a warm-up operation.
FIG. 6 is a flowchart showing a processing procedure of drive control of each heater during a warm-up operation.
FIG. 7 is a flowchart showing a drive control processing procedure according to the heating state of the heating roller by each heater when a print start request is made.
FIG. 8 is a timing chart showing drive timings of a main heater, a sub heater, and a paper conveyance drive unit.
[Explanation of symbols]
1 Image forming device
23 Fixing device
231 Heating roller
232 Halogen heater
232a Main heater
232b Sub-heater
233a Main thermistor
233b Sub thermistor
236 Temperature detector
237 Fixing drive
2371 Engine control unit
2372 heater drive
238 Paper transport drive

Claims (7)

Heating roller, first heating means and second heating means for heating the heating roller, first temperature detecting means for detecting the temperature of the portion heated by the first heating means, and heating by the second heating means A second temperature detecting means for detecting the temperature of the heated portion, and the first heating means and the second heating means are individually driven based on the detected temperatures of the first and second temperature detecting means, and the heating roller is moved. In a fixing device provided with a control means for controlling heating,
During a warm-up operation for controlling the heating roller until the printable state from power-on or until the printer is ready for printing from the standby state, the control means does not increase the temperature until the heating roller is raised to the print start temperature. Both heating means are driven, and when the temperature detected by the first temperature detecting means or the second temperature detecting means reaches the print start temperature, the driving of the heating means that has reached is stopped, and thereafter the other temperature detecting means A fixing device that performs a temperature adjusting operation so as to be a control temperature during a printing operation by a heating unit. After the end of the warm-up operation, the control unit starts driving the heating unit when the temperature of the heating unit stopped at the end of the warm-up operation falls below the lower limit value of the printable temperature range, 2. The fixing device according to claim 1, wherein driving of the heating unit that has been driven is stopped at that time, and thereafter, the temperature adjusting operation is performed by the heating unit that has started driving. The control means repeats the temperature adjustment operation by repeating the start of driving of the heating means and the stop of driving of the other heating means each time the temperature of the heating means having stopped driving falls below the lower limit value of the printable temperature range. The fixing device according to claim 2, wherein the fixing device is continued. The first heating unit includes a main heater that preferentially heats the vicinity of the center portion in the width direction of the heating roller, and the second heating unit heats the vicinity of both ends of the heating roller in the width direction. The fixing device according to claim 1, comprising a sub-heater. When starting the printing, the control means detects the first temperature detection means or the second temperature detection means when the temperature is below the printable temperature range, or the first temperature detection means or the second temperature detection means. Both the first heating unit and the second heating unit are driven and the driving of the heating unit that has reached the printing start temperature is stopped, and the printing operation is started after the other heating unit reaches the control temperature during the printing operation. On the other hand, when both the first temperature detecting means and the second temperature detecting means detect a temperature within the printable temperature range, the lower one of the first and second temperature detecting means. 5. The fixing according to claim 1, wherein the temperature control operation is performed so that the temperature is controlled by the heating means indicating the temperature, and the printing operation is immediately started. apparatus. 2. The fixing device according to claim 1, wherein the printing start temperature is set to a temperature lower than a control temperature during the printing operation within a printable temperature range. An image forming apparatus comprising the fixing device according to any one of claims 1 to 6.
A sheet conveying means for conveying the sheet to the image forming area;
The control unit stops driving the sheet conveying unit while driving both the first heating unit and the second heating unit, and either the first heating unit or the second heating unit is stopped. An image forming apparatus that drives the sheet conveying means when the printer is driven.

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