JP2020008880A - Fixing device and program for controlling fixing temperature of fixing device - Google Patents

Abstract

To enable intensive and stable heating of a paper feed area to achieve improvement of fixing quality and energy savings.SOLUTION: A fixing device comprises: determination means that determines the size of an image forming area of a medium on which a toner image is formed; heating means that has an endless-shape rotating body, a plurality of heating members formed in a direction at a right angle to a conveyance direction of the medium, obtained by being divided at a predetermined length, and arranged in contact with the inside of the rotating body, and a switching part that switches energization individually to the heating members; pressure means that is in pressure contact with the heating means at the positions of the plurality of heating members to form a nip, and holds and conveys the medium in the conveyance direction with the heating means; and heating control means that controls heating performed by the heating means by selecting, with the switching part, an element of the heating member corresponding to a position through which an image forming area of the medium passes and energizing the heating member.SELECTED DRAWING: Figure 7

Description

  The present embodiment relates to a fixing device and a fixing temperature control program for the fixing device.

  As a heat source of a fixing device mounted on an image forming apparatus, a lamp that emits infrared rays represented by a halogen lamp, or a method of heating with Joule heat by electromagnetic induction has been put to practical use.

  Generally, a fixing device is composed of a pair of a heating roller (or a fixing belt stretched over a plurality of rollers) and a press roller. In order to maximize the thermal efficiency of the fixing device, the heat capacity of components is reduced as much as possible. In addition, it is required that the heating region be concentrated. From this viewpoint, in the above-described heating method, since the heating width is wide, it is difficult to apply heat energy dispersed over a wide area only to the nip portion, and it is difficult to optimize thermal efficiency.

  Further, in the fixing device for electrophotography, if heat generation unevenness occurs in a direction perpendicular to the sheet conveying direction, the fixing quality is affected. In particular, in the case of color printing, there is a possibility that a difference occurs in color development and gloss.

  Further, in a fixing device in which the heat capacity is extremely reduced, since the temperature of a portion through which the sheet does not pass is extremely increased, problems such as warpage of the heater, deterioration of the belt, and speed unevenness due to expansion of the conveyance roller may occur. Was. Heating a portion through which the paper does not pass is not preferable from the viewpoint of energy saving. Intensive heating of only the portion where the paper passes is an important technical issue from the viewpoint of environmental measures.

JP-A-2000-243537

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and provides a fixing device and a fixing temperature control program for the fixing device, which enable intensive and stable heating of a paper passing area, and achieve improvement in fixing quality and energy saving. With the goal.

  The fixing device according to the present exemplary embodiment includes a determination unit that determines a size of an image forming area of a medium on which a toner image is formed, an endless rotating body, and a rotating body that is formed in a direction perpendicular to a transport direction of the medium and has a predetermined shape. A plurality of heating members arranged in contact with the inside of the rotating body, and a switching unit that individually switches energization to these heating members, and heating means for heating the medium. A pressurizing unit that presses the heating unit at the positions of the plurality of heat generating members to form a nip, and presses and conveys the medium in the conveying direction together with the heating unit; and the image forming area of the medium passes therethrough. And a heating control unit that controls the heating by the heating unit by selecting a heating member corresponding to a position by the switching unit and energizing the heating unit.

FIG. 2 is a diagram illustrating a configuration example of an image forming apparatus in which the fixing device according to the first embodiment is mounted. FIG. 2 is an enlarged configuration diagram illustrating a part of an image forming unit according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration example of a control system of the MFP according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of a fixing device according to the first embodiment. FIG. 2 is a layout diagram of a heat generating member group according to the first embodiment. FIG. 3 is a diagram illustrating a connection state between a heat generating member group and a drive circuit thereof according to the first embodiment. FIG. 3 is a diagram illustrating a positional relationship between a heat generating member group and a print area of a sheet according to the first embodiment. 5 is a flowchart illustrating a specific example of a control operation of the MFP according to the first embodiment. FIG. 10 is a layout diagram of a heat generating member group according to the second embodiment. FIG. 9 is a diagram illustrating a connection state between a heat generating member group and a driving circuit thereof when a sheet size is a minimum in the second embodiment. 9 is a flowchart illustrating a specific example of a control operation of the MFP according to the second embodiment.

<First embodiment>
FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus in which a fixing device according to the present embodiment is mounted. In FIG. 1, an image forming apparatus 10 is, for example, an MFP (Multi-Function Peripherals) as a multifunction peripheral, a printer, a copier, or the like. In the following description, an MFP will be described as an example.

  An upper portion of a main body 11 of the MFP 10 has a transparent glass platen 12, and an automatic document feeder (ADF) 13 is provided on the platen 12 so as to be openable and closable. Further, an operation panel 14 is provided on an upper portion of the main body 11. The operation panel 14 has various keys and a touch panel display unit.

  A scanner unit 15 as a reading device is provided below the ADF 13 in the main body 11. The scanner unit 15 reads a document sent by the ADF 13 or a document placed on a document table to generate image data, and includes a contact image sensor 16 (hereinafter, simply referred to as an image sensor). The image sensor 16 is arranged in the main scanning direction (the depth direction in FIG. 1).

  When reading an image of a document placed on the document table 12, the image sensor 16 reads the document image one line at a time while moving along the document table 12. This is performed over the entire size of the document, and one page of the document is read. When reading an image of a document sent by the ADF 13, the image sensor 16 is at a fixed position (the position shown).

  Further, a printer unit 17 is provided at a central portion in the main body 11, and a plurality of paper feed cassettes 18 for storing sheets P of various sizes are provided at a lower portion of the main body 11. The printer unit 17 has a photosensitive drum and a scanning head 19 including an LED as an exposure device, and scans the photosensitive member with a light beam from the scanning head 19 to generate an image.

  The printer unit 17 processes image data read by the scanner unit 15 and image data created by a personal computer or the like to form an image on paper. The printer unit 17 is, for example, a tandem-type color laser printer, and includes image forming units 20Y, 20M, 20C, and 20K for yellow (Y), magenta (M), cyan (C), and black (K). The image forming units 20Y, 20M, 20C, and 20K are arranged in parallel below the intermediate transfer belt 21 from upstream to downstream. The scanning head 19 also has a plurality of scanning heads 19Y, 19M, 19C, 19K corresponding to the image forming units 20Y, 20M, 20C, 20K.

  FIG. 2 is a configuration diagram showing, on an enlarged scale, the image forming unit 20K among the image forming units 20Y, 20M, 20C, and 20K. In the following description, since the image forming units 20Y, 20M, 20C, and 20K have the same configuration, the image forming unit 20K will be described as an example.

  The image forming section 20K has a photosensitive drum 22K as an image carrier. Around the photosensitive drum 22K, a charging charger 23K, a developing device 24K, a primary transfer roller (transfer device) 25K, a cleaner 26K, a blade 27K, and the like are arranged along the rotation direction t. The scanning head 19K irradiates light to the exposure position of the photosensitive drum 22K to form an electrostatic latent image on the photosensitive drum 22K.

  The charging charger 23K of the image forming unit 20K uniformly charges the surface of the photosensitive drum 22K. The developing device 24K supplies a two-component developer containing black toner and carrier to the photosensitive drum 22K by the developing roller 24a to which a developing bias is applied, and develops the electrostatic latent image. The cleaner 26K uses a blade 27K to remove residual toner on the surface of the photoconductor drum 22K.

  Further, as shown in FIG. 1, a toner cartridge 28 for supplying toner to the developing units 24Y to 24K is provided above the image forming units 20Y to 20K. The toner cartridge 28 includes a toner cartridge of each color of yellow (Y), magenta (M), cyan (C), and black (K).

  The intermediate transfer belt 21 moves cyclically. The intermediate transfer belt 21 is stretched around a driving roller 31 and a driven roller 32. The intermediate transfer belt 21 is in contact with and contacts the photosensitive drums 22Y to 22K. A primary transfer voltage is applied by a primary transfer roller 25K to a position of the intermediate transfer belt 21 facing the photoconductor drum 22K, and the toner image on the photoconductor drum 22K is primarily transferred to the intermediate transfer belt 21.

  A secondary transfer roller 33 is disposed to face the drive roller 31 that stretches the intermediate transfer belt 21. When the paper P passes between the driving roller 31 and the secondary transfer roller 33, a secondary transfer voltage is applied to the paper P by the secondary transfer roller 33. Then, the toner image on the intermediate transfer belt 21 is secondarily transferred to the sheet P. A belt cleaner 34 is provided near the driven roller 32 of the intermediate transfer belt 21.

  As shown in FIG. 1, a paper feed roller 35 is provided between the paper feed cassette 18 and the secondary transfer roller 33 to transport the paper P taken out of the paper feed cassette 18. Further, a fixing device 36 is provided downstream of the secondary transfer roller 33. Further, a transport roller 37 is provided downstream of the fixing device 36. The transport roller 37 discharges the paper P to a paper discharge unit 38. Further, a reversing conveyance path 39 is provided downstream of the fixing device 36. The reverse transport path 39 reverses the sheet P and guides the sheet P toward the secondary transfer roller 33, and is used when performing double-sided printing. FIGS. 1 and 2 show an embodiment of the present invention, and do not limit the structure of the image forming apparatus other than the fixing device 36. The structure of a known electrophotographic image forming apparatus may be used. it can.

  FIG. 3 is a block diagram illustrating a configuration example of the control system 50 of the MFP 10 according to the first embodiment. The control system 50 includes, for example, a CPU 100 that controls the entire MFP 10, a read-only memory (ROM) 120, a random access memory (RAM) 121, an interface (I / F) 122, an input / output control circuit 123, and a paper feed / transport control circuit. 130, an image forming control circuit 140, and a fixing control circuit 150.

  The CPU 100 realizes a processing function for image formation by executing a program stored in the ROM 120 or the RAM 121. The ROM 120 stores a control program, control data, and the like that control the basic operation of the image forming process. The RAM 121 is a working memory. The ROM 120 (or the RAM 121) stores, for example, a control program for the image forming unit 20, the fixing device 36, and the like, and various control data used by the control program. As a specific example of the control data in the present embodiment, there is a correspondence relationship between the size of the print area (width in the main scanning direction) on the paper and the heating member to be energized.

  The fixing temperature control program of the fixing device 36 includes a determination logic for determining the size of the image forming area on the sheet on which the toner image is formed, and the image forming area passing before the sheet is conveyed into the fixing apparatus 36. A heating control logic for selecting a switching element of the heat generating member corresponding to the position, energizing the switching element, and controlling heating in the heating means.

  The I / F 122 performs communication with various devices such as a user terminal and a facsimile. The input / output control circuit 123 controls the operation panel 123a and the display 123b. The paper feed / transport control circuit 130 controls a motor group 130a for driving the paper feed roller 35, the transport roller 37 in the transport path, and the like. The paper feed / transport control circuit 130 controls the motor group 130a and the like based on a control signal from the CPU 100 in consideration of detection results of various sensors 130b near the paper feed cassette 18 or on the transport path. The image forming control circuit 140 controls the photosensitive drum 22, the charging device 23, the scanning head 19, the developing device 24, and the transfer device 25 based on a control signal from the CPU 100. The fixing control circuit 150 controls the drive motor 360 of the fixing device 36, the heating member 361, and the temperature detecting member 362 such as a thermistor based on a control signal from the CPU 100. In this embodiment, the control program and the control data of the fixing device 36 are stored in the storage device of the MFP 10 and executed by the CPU 100. However, the arithmetic processing device and the storage device are separately provided exclusively for the fixing device 36. You may.

  FIG. 4 is a diagram illustrating a configuration example of the fixing device 36. Here, the fixing device 36 applies tension to the plate-shaped heating member 361, the endless belt 363 formed with an elastic layer and suspended by a plurality of rollers, the belt transport roller 364 that drives the endless belt 363, and the endless belt 363. A tension roller 365 and a press roller 366 having an elastic layer formed on its surface are provided. The heating member 361 contacts the inside of the endless belt 363 on the heat generating portion side and is pressed in the direction of the press roller 366, thereby forming a fixing nip having a predetermined width between the heating member 361 and the press roller 366. Since the heating member 361 heats while forming the nip region, the response during energization is higher than in the case of the heating method using a halogen lamp.

  The endless belt 363 has, for example, a 200 μm thick silicon rubber layer formed on the outside of a 50 μm thick SUS base or 70 μm heat-resistant resin polyimide, and the outermost periphery is covered with a surface protection layer such as PFA. . The press roller 366 has, for example, a 5 mm thick silicon sponge layer formed on the surface of an iron bar having a diameter of 10 mm, and the outermost periphery is covered with a surface protection layer such as PFA.

  Further, the heating member 361 has a glaze layer and a heating resistance layer laminated on a ceramic substrate. An aluminum heat sink is bonded to the opposite side to release excess heat and prevent the board from warping. The heating resistance layer is formed of a known material such as TaSiO2, for example, and is divided into a predetermined length and a predetermined number in the main scanning direction.

  The method of forming the heating resistor layer is the same as a known method (for example, a method of forming a thermal head), and a masking layer of aluminum is formed on the heating resistor layer. The aluminum layer is formed in a pattern such that the adjacent heating members are insulated and the heating resistors (heating members) are exposed in the paper transport direction. When power is supplied to the heat generating member 361a, wiring is connected from the aluminum layers (electrodes) at both ends, and each is connected to the switching element of the switching driver IC. Further, a protective layer is formed on the uppermost portion so as to cover all of the heating resistor, the aluminum layer, the wiring, and the like. The protective layer is formed of, for example, Si3N4.

  FIG. 5 is a layout diagram of the heat generating member group in the present embodiment, and FIG. 6 is a diagram illustrating a connection state between the heat generating member group and a driving circuit thereof. As shown in these figures, a plurality of heating members 361a having a predetermined width are arranged side by side in the main scanning direction (horizontal direction in the drawing) on the ceramic substrate. The electrodes 361b are formed at both ends in the (direction). It is shown that the energization of each of the heat generating members 361a is individually controlled by the corresponding drive ICs 151a to 151d. Specific examples of the drive ICs 151a to 151d, which are switching units of the heat generating member 361a, include a switching element, an FET, a triax, and a switching IC.

  FIG. 7 is a diagram illustrating a positional relationship between the heat generating member group and a print area of a sheet according to the first embodiment. Here, when the paper P is transported in the paper transport direction indicated by the arrow A, only the heat generating member 361a corresponding to the position where the print area (image forming area) of the paper passes is selectively energized and heated. Is shown. That is, only the printing area of the paper P is intensively heated. In the present embodiment, it is assumed that the size of the print area of the paper P is determined before the paper P is transported into the fixing device 36. Examples of the method for determining the print area of the paper P include a method using an analysis result of image data, a method based on print format information such as a margin setting for the paper P, and a method based on a detection result of an optical sensor. Can be

  Hereinafter, the printing operation of the MFP 10 configured as described above will be described with reference to the drawings. FIG. 8 is a flowchart illustrating a specific example of control of the MFP 10 according to the first embodiment.

  First, when image data is read by the scanner unit 15 (Act 101), the image forming control program in the image forming unit 20 and the fixing temperature control program in the fixing device 36 are executed in parallel.

  When the image forming process is started, the read image data is processed (Act 102), an electrostatic latent image is written on the surface of the photosensitive drum 22 (Act 103), and the developing device 24 develops the electrostatic latent image. (Act 104), the process proceeds to Act 114.

  On the other hand, when the fixing temperature control process is started, the paper size and image data are printed based on, for example, a detection signal of a line sensor (not shown), paper selection information from the operation panel 14, or an analysis result of the image data. The size of each range is determined (Act 105), and a heat generating member group arranged at a position where the print range of the paper P passes is selected as a heat generation target (Act 106). For example, in the example shown in FIG. 7, 14 heat generating members 361a arranged at the center corresponding to the width of the print area are selected.

  Next, when the temperature control start signal for the selected heat generating member group is turned ON (Act 107), power is supplied to the selected heat generating member group, and the temperature rises.

  Next, when the surface temperature of the heat generating member group is detected by a temperature detecting member (not shown) disposed inside or outside the endless belt 363 (Act 108), whether the surface temperature of the heat generating member group is within a predetermined temperature range is determined. It is determined whether or not it is not (Act 109). Here, when it is determined that the surface temperature of the heat generating member group is within the predetermined temperature range (Act 109: Yes), the process proceeds to Act 110. On the other hand, when it is determined that the surface temperature of the heat generating member group is not within the predetermined temperature range (Act 109: No), the process proceeds to Act 111.

  In Act 111, it is determined whether or not the surface temperature of the heat generating member group exceeds a predetermined temperature upper limit. Here, when it is determined that the surface temperature of the heating member group exceeds the predetermined temperature upper limit value (Act111: Yes), the power supply to the heating member group selected in Act106 is turned off (Act112), It returns to Act108. On the other hand, when it is determined that the surface temperature of the heat generating member group does not exceed the predetermined upper temperature limit (Act111: No), the determination result of Act109 indicates that the surface temperature is less than the predetermined lower temperature limit. Therefore, the power supply to the heat generating member group is maintained in the ON state, or turned on again (Act 113), and the process returns to Act 108.

  Next, when the sheet P is conveyed to the transfer unit in a state where the surface temperature of the heat generating member group is within the predetermined temperature range (Act 110), after the toner image is transferred onto the sheet P (Act 114), the sheet P is fixed to the fixing device. It is transported into 36.

  Next, when the toner image is fixed on the paper P in the fixing device 36 (Act 115), it is determined whether or not to end the image data printing process (Act 116). If it is determined that the printing process is to be ended (Act 116: Yes), the power supply to all the heat generating member groups is turned off (Act 117), and the process ends. On the other hand, when it is determined that the print processing of the image data has not been completed yet (Act 116: No), that is, when the image data to be printed remains, the process returns to Act 101 and repeats the same processing until the end. .

  As described above, in the fixing device 36 according to the present embodiment, the heating member 361 is divided into a heat generating member group having a predetermined length in a direction perpendicular to the sheet P conveying direction, and is disposed in contact with the inside of the endless belt 363. In addition, a configuration is such that heat is selectively supplied to a heat generating member group through which a print range (image forming area) of image data passes. By switching the heat generation area based on the size of the print range of the image data, not only the abnormal heat generation in the non-paper passing portion can be prevented, but also the unnecessary heating of the non-paper passing portion can be suppressed, so that the fixing device 36 consumes. Thermal energy can be significantly reduced. In addition, since intensive and stable heating of the printing portion can be performed, fixing quality can be improved.

<Embodiment 2>
Hereinafter, the fixing device 36 according to the second embodiment will be described with reference to the drawings. Note that the configuration of the MFP 10 in the present embodiment is the same as that of the first embodiment, and the same reference numerals as those in the first embodiment also denote the same objects. The following description focuses on the differences from the first embodiment.

  FIG. 9 is an arrangement diagram of a heat generating member group according to the second embodiment. The heating member 361 has a plurality of lengths of heating members corresponding to postcard size (100 × 148 mm), CD jacket size (121 × 121 mm), B5R size (182 × 257 mm), and A4R size (210 × 297 mm). This is different from the first embodiment in that it is divided into a heating element 361a. The heat generating member group is energized so as to have a margin of about 5% in the heated area in consideration of the transport accuracy of the transported paper, the skew, and the escape of heat to the non-heated portion.

  For example, in order to correspond to a postcard size width of 100 mm, which is the minimum size, a first heat generating member group is provided at the center in the main scanning direction (left and right directions in the drawing), and its width is 105 mm. In order to correspond to the next largest sizes 121 mm and 148 mm, a second heating member group having a width of 50 mm is provided outside the first heating member group (in the horizontal direction in the drawing) to cover a width of 148 mm + 5% up to 155 mm. To accommodate even larger sizes of 182 mm and 210 mm, a third heat generating member group having a width of each heat generating member of 65 mm is provided further outside the second heat generating member group, and covers a width up to 220 mm at 210 mm + 5%. . Note that the number of divisions and the width of each of the heat generating member groups are given as an example, and are not limited thereto. For example, when the MFP 10 supports five medium sizes, the heat generating member group may be divided into five according to each medium size.

  In the present embodiment, it is assumed that a line sensor (not shown) is arranged in the paper passing area, and the size and position of the passing paper can be determined in real time. At the start of the printing operation, the paper size may be determined based on the image data or information on the paper cassette 18 in which the paper in the MFP 10 is stored.

  FIG. 10 is a diagram illustrating a connection state of the heat generating member group and its drive circuit when the paper size is the minimum size. Here, it is shown that, when the paper P is the minimum size (postcard size), only the switching element of the first heat generating member disposed at the center is turned ON and heated. As the size of the sheet P increases, the switching elements of the second heat generating member group and the third heat generating member group are controlled so as to be sequentially turned on.

  Hereinafter, the printing operation of the MFP 10 according to the present embodiment will be described with reference to the drawings. FIG. 11 is a flowchart illustrating a specific example of control of the MFP 10 according to the second embodiment.

  First, when image data is read by the scanner unit 15 (Act 201), the image forming control program in the image forming unit 20 and the fixing temperature control program in the fixing device 36 are executed in parallel.

  When the image forming process is started, the read image data is processed (Act 202), an electrostatic latent image is written on the surface of the photosensitive drum 22 (Act 203), and the electrostatic latent image is developed by the developing device 24. (Act 204), the process proceeds to Act 214.

  When the fixing temperature control process is started, the sheet size is determined based on, for example, a detection signal of a line sensor (not shown) and sheet selection information from the operation panel 14 (Act 205), and the sheet is placed at a position where the sheet P passes. The selected heating member group is selected as a heating target (Act 206).

  Next, when the temperature control start signal for the selected heat generating member group is turned ON (Act 207), power is supplied to the selected heat generating member group, and the surface temperature of the heat generating member group increases.

  Next, when the surface temperature of the heat generating member group is detected by a temperature detecting member (not shown) disposed inside or outside the endless belt 363 (Act 208), whether the surface temperature of the heat generating member group is within a predetermined temperature range is determined. It is determined whether or not it is not (Act 209). Here, when it is determined that the surface temperature of the heat generating member group is within the predetermined temperature range (Act 209: Yes), the process proceeds to Act 210. On the other hand, when it is determined that the surface temperature of the heat generating member group is not within the predetermined temperature range (Act 209: No), the process proceeds to Act 211.

  In Act 211, it is determined whether or not the surface temperature of the heat generating member group exceeds a predetermined temperature upper limit. Here, when it is determined that the surface temperature of the heat generating member group exceeds the predetermined temperature upper limit (Act 211: Yes), the power supply to the heat generating member group selected in Act 206 is turned off (Act 212). Return to Act 208. On the other hand, when it is determined that the surface temperature of the heat generating member group does not exceed the predetermined temperature upper limit value (Act 211: No), it is determined in Act 209 that the surface temperature is less than the predetermined lower temperature limit. Therefore, the power supply to the heat generating member group is maintained in the ON state or turned ON again (Act 213), and the process returns to Act 208.

  Next, when the sheet P is conveyed to the transfer unit in a state where the surface temperature of the heat generating member group is within the predetermined temperature range (Act 210), after the toner image is transferred onto the sheet P (Act 214), the sheet P is fixed to the fixing device. It is transported into 36.

  Next, when the toner image is fixed on the paper P in the fixing device 36 (Act 215), it is determined whether or not to end the image data printing process (Act 216). If it is determined that the printing process is to be ended (Act 216: Yes), the power supply to all the heat generating member groups is turned off (Act 217), and the process ends. On the other hand, if it is determined that the printing process of the image data has not been completed yet (Act 216: No), that is, if the image data to be printed remains, the process returns to Act 201, and the same process is repeated until it is completed. .

  As described above, the fixing device 36 according to the present embodiment classifies the size of the paper P into a plurality of groups, selects the switching elements of the heating members belonging to the heating member group previously associated with the group, and simultaneously selects the switching elements. It is a configuration to energize.

  By switching the heating member group to be heated based on the group to which the paper size to be used belongs, it is possible not only to prevent abnormal heating of the non-sheet passing portion but also to suppress unnecessary heating of the non-sheet passing portion. As in the case of Embodiment 1, the heat energy consumed by the fixing device 36 can be significantly reduced. In addition, in the case of the first embodiment in which the switching of the heating target is performed not in the individual heating members but in units of the heating members, the determination logic in the control program is simplified, and the determination is performed based on the print range of the image data. There is also an advantage that it can be easily mounted as compared with.

  The embodiments of the present invention have been described above. However, the present embodiments are presented as examples, and are not intended to limit the scope of the invention. The new embodiment can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The present embodiment and its modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

  For example, the configurations of Embodiment 1 and Embodiment 2 may be combined. That is, in the second embodiment, the heat generating member group may be selected based on the size of the print size (image forming area) as in the first embodiment instead of the sheet size.

36 fixing device 150 fixing device control circuits 151, 151a, 151b, 151c, 151d driving IC
361 heating member 361a heating member 362b electrode 363 endless belt 366 pressure roller

The fixing device of the present embodiment is divided determination means for determining the size of the medium on which the toner image has been formed, the rotating body of the endless shape, the length of the plurality of types in the conveying direction and perpendicular direction of the medium Rutotomoni , Each of which is separated by a gap along the transport direction, and among the plurality of heat generating members arranged in contact with the inside of the rotating body, the length in the perpendicular direction of the medium having the minimum size in the perpendicular direction is A first heat generating member longer than the first heat generating member, and a plurality of the heat generating members other than the first heat generating member, each of which has a length in the right angle direction shorter than the length in the right angle direction of the medium having the minimum size. The second heating member and the first heating member are energized regardless of the result of the determination of the size of the medium, and the result of the determination of the size of the medium indicates that the length of the medium in the perpendicular direction is the minimum. Size of the medium When indicating that longer than the length of the perpendicular direction, by energizing one or more of a plurality of said second heat generating member corresponding to the position where the medium passes through a heating means for heating the medium, the heating pressed against at a location of the plurality of the heating member to form a nip section, and a pressure means for holding and conveying the medium to the conveying direction together with the heating means, Ru comprising a.

Claims (5)

Determining means for determining the size of the image forming area of the medium on which the toner image is formed;
An endless rotating body, a plurality of heating members formed in a direction perpendicular to the direction of transport of the medium, divided into predetermined lengths, and arranged in contact with the inside of the rotating body; A switching unit for individually switching the energization to, heating means for heating the medium,
Pressurizing means for pressing the heating means at the positions of the plurality of heat generating members to form a nip, and nipping and conveying the medium in the conveying direction together with the heating means;
A heating control unit that selects a heating member corresponding to a position where the image forming area of the medium passes by the switching unit, energizes the heating unit, and controls heating in the heating unit.
A fixing device comprising:   2. The fixing device according to claim 1, wherein the determining unit determines the size of the image forming area of the medium based on an analysis result of the image data or print format information defined in advance corresponding to the medium. apparatus. Determining means for determining the size of the medium on which the toner image is formed;
An endless rotating body, a plurality of heating members formed in a direction perpendicular to the medium transport direction and divided into a plurality of lengths, and arranged in contact with the inside of the rotating body; A heating unit for heating the medium, comprising: a switching unit that individually switches energization to the member;
Pressurizing means for pressing the heating means at the positions of the plurality of heat generating members to form a nip, and nipping and conveying the medium in the conveying direction together with the heating means;
Heating control means for selecting a heating member corresponding to a position through which the medium passes by the switching unit and energizing the same, and controlling heating in the heating means,
A fixing device comprising:   The judging means classifies the size of the medium into a plurality of groups, and the heating control means selects the heat generating members belonging to a heat generating member group associated in advance with the classification by the switching section and simultaneously energizes the heat generating members. The fixing device according to claim 3, wherein: The medium includes a plurality of heating members formed in a direction perpendicular to the transport direction of the medium on which the toner image is formed and divided by a predetermined length, and a switching unit that individually switches energization to the heating members. A fixing temperature control program for a fixing device that pressurizes and heats the toner image to fix the toner image onto the medium,
A determining step of determining a size of an image forming area of the medium;
A heating control step of selecting a heating member corresponding to a position where the image forming area of the medium passes by the switching unit and energizing the heating member, and controlling heating by the heating member;
Temperature control program for a fixing device, wherein the program causes a computer to execute the program.

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