JP6695410B2 - Heating member and image forming apparatus - Google Patents

Description

The present embodiment relates to a heating member and an image forming apparatus.

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

  Generally, a fixing device is composed of a pair of a heating roller (or a fixing belt wound around a plurality of rollers) and a press roller, but in order to maximize the thermal efficiency of the fixing device, the heat capacity of the constituent elements is reduced as much as possible. In addition, it is required to concentrate the heating area.

Japanese Patent No. 2629980

  In the above-mentioned heating method, since the heating width is wide, it is difficult to concentrate the heat energy dispersed in a wide range only on the nip portion, and it is difficult to optimize the thermal efficiency. Further, in the fixing device for electrophotography, if uneven heat generation occurs in the 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 differences in color development and gloss will occur.

  Further, in a fixing device having an extremely reduced heat capacity, the temperature of a portion where the paper does not pass extremely rises, which may cause problems such as warping of the heater, deterioration of the belt, and uneven speed due to expansion of the conveying roller. It was Further, it is not preferable to heat the portion where the paper does not pass from the viewpoint of energy saving. Centrally heating only the part through which the paper passes is an important technical issue from the viewpoint of environmental protection.

  For this reason, it has been proposed to control by dividing the heat generation area.However, when dividing the heat generation area, it is necessary to consider the operating voltage value and installation environment etc. Since the creepage distance or the spatial distance in the boundary portion between the members must be set to a certain value or more, a temperature drop occurs in that portion, and as a result, the fixing quality is lowered due to the temperature unevenness.

  Therefore, in view of the above-mentioned problems of the prior art, it is an object of the present invention to enable intensive and stable heating of a paper passing area, and to achieve improvement in fixing quality and energy saving.

The heating member according to one embodiment includes an insulator and a heat generating member. A plurality of heat-generating member is disposed on the surface of the insulator, is split into a plurality Te conveying direction perpendicular to the direction odor of the medium, are energized respectively by heating the medium. The creepage distance of the insulator between the plurality of heat generating members is longer than the distance between the plurality of heat generating members .

FIG. 1 is a diagram showing a configuration example of an image forming apparatus in which a fixing device according to an embodiment is mounted. FIG. 3 is a configuration diagram showing an enlarged part of an image forming unit according to an embodiment. 3 is a block diagram showing a configuration example of a control system of the MFP according to the embodiment. FIG. FIG. 3 is a diagram showing a configuration example of a fixing device according to an embodiment. FIG. 3 is a layout diagram of a heat generating member group according to an embodiment. Sectional drawing explaining the creeping distance between the heat generating members after a division | segmentation in one Embodiment. FIG. 3 is a diagram showing a connection state of a heat generating member group and its drive circuit in one embodiment. 6 is a flowchart showing a specific example of control operation of the MFP according to the embodiment. Sectional drawing which shows the fixing structure of the heat generating member and the ceramic substrate in the modification of one Embodiment. The figure which shows the shape pattern of the heat generating member group in the modification of one Embodiment. The figure which shows the shape pattern of the heat generating member group in the modification of one Embodiment.

  Hereinafter, a fixing device according to an exemplary embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration example of an image forming apparatus in which the fixing device according to the present embodiment is mounted. In FIG. 1, the image forming apparatus 10 is, for example, an MFP (Multi-Function Peripherals) that is a multifunction machine, a printer, a copying machine, or the like. In the following description, the MFP will be described as an example.

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

  Below the ADF 13 in the main body 11, a scanner unit 15 which is a reading device is provided. The scanner unit 15 reads an original sent by the ADF 13 or an original placed on an original 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 (depth direction in FIG. 1).

  When reading an image of a document placed on the document table 12, the image sensor 16 moves along the document table 12 and reads the document image line by line. This is executed over the entire document size to read one page of the document. Further, when reading an image of a document sent by the ADF 13, the image sensor 16 is at a fixed position (position shown in the figure).

  Further, a printer section 17 is provided in the center of the main body 11, and a plurality of paper feed cassettes 18 for accommodating sheets P of various sizes are provided in the lower part of the main body 11.

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

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

  The image forming unit 20K has a photosensitive drum 22K that is an image carrier. Around the photosensitive drum 22K, a charging device (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 laser exposure device 19K irradiates the exposure position of the photoconductor drum 22K with light to form an electrostatic latent image on the photoconductor drum 22K.

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

  Further, as shown in FIG. 1, a toner cartridge 28 that supplies toner to the developing units 24Y to 24K is provided above the image forming units 20Y to 20K. The toner cartridge 28 includes toner cartridges 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. Further, the intermediate transfer belt 21 faces and contacts the photoconductor 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 opposed to the photosensitive drum 22K, and the toner image on the photosensitive drum 22K is primarily transferred to the intermediate transfer belt 21.

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

  Further, as shown in FIG. 1, a paper feed roller 35 that conveys the paper P taken out from the paper feed cassette 18 is provided between the paper feed cassette 18 and the secondary transfer roller 33. Further, a fixing device 36 is provided downstream of the secondary transfer roller 33. A transport roller 37 is provided downstream of the fixing device 36. The transport roller 37 discharges the paper P to the paper discharge unit 38. Further, a reversal conveyance path 39 is provided downstream of the fixing device 36. The reverse conveyance path 39 reverses the sheet P and guides it toward the secondary transfer roller 33, and is used when performing double-sided printing. 1 and 2 show an example of the configuration of the MFP 10. The structure of the image forming apparatus other than the fixing device 36 is not limited, and the structure of a known electrophotographic image forming apparatus can be used.

  FIG. 3 is a block diagram showing a configuration example of the control system 50 of the MFP 10 in this embodiment. The control system 50 is, 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, a paper feed / conveyance control circuit. An image forming control circuit 140, a fixing control circuit 150 are provided.

  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 and control data that control basic operations of image forming processing. 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. Specific examples of the control data in the present embodiment include a correspondence relationship between the size (width in the main scanning direction) of the paper passing area or the print area in the paper and the heat generating member to be energized.

  The fixing temperature control program of the fixing device 36 determines the size of the image forming area on the paper on which the toner image is formed, and a fixing temperature control program for the paper passing area before the paper is conveyed into the fixing device 36. And a heating control logic for controlling the heating in the heating means by selecting the corresponding switching element of the heat generating member to energize it.

  The I / F 122 communicates 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 device 123b that form the operation unit 14. The paper feed / conveyance control circuit 130 controls a motor group 130a or the like that drives the paper feed roller 35 or the conveyance roller 37 of the conveyance path. The paper feed / conveyance control circuit 130 controls the motor group 130a and the like in consideration of detection results of various sensors 130b near the paper feed cassette 18 or on the conveyance path based on a control signal from the CPU 100. The image forming control circuit 140 controls the photoconductor drum 22, the charger 23, the laser exposure device 19, the developing device 24, and the transfer device 25 based on the 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 the control signal from the CPU 100. In the present embodiment, the control program and control data for the fixing device 36 are stored in the storage device of the MFP 10 and executed by the CPU 100. However, an arithmetic processing unit and a storage device are separately provided for the fixing device 36. May be.

  FIG. 4 is a diagram showing 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 suspended by a plurality of rollers, the belt conveying 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 heating portion side and is pressed in the direction of the press roller 366, thereby forming a fixing nip of a predetermined width with the press roller 366. Since the heating member 361 heats while forming the nip region, the responsiveness during energization is higher than in the case of the heating method using a halogen lamp.

  The endless belt 363 has, for example, a SUS substrate having a thickness of 50 μm or a polyimide layer which is a heat-resistant resin having a thickness of 70 μm and a silicone rubber layer having a thickness of 200 μm formed on the outer side, and the outermost periphery is covered with a surface protective layer such as PFA. .. In the press roller 366, a silicon sponge layer having a thickness of 5 mm is formed on the surface of an iron rod of φ10 mm, for example, and the outermost periphery is covered with a surface protective layer such as PFA.

  In addition, the heating member 361 has a glaze layer and a heating resistance layer laminated on a ceramic substrate. The heat generating resistance layer is formed of a known material such as TaSiO2 in order to allow excess heat to escape to the opposite side and prevent the substrate from warping, and is divided into a predetermined length and number in the main scanning direction.

  The method of forming the heating resistance layer is the same as a known method (for example, a method of forming a thermal head), and a masking layer is formed of aluminum on the heating resistance layer. An aluminum layer is formed in a pattern such that adjacent heat generating members are insulated from each other and the heat generating resistors (heat generating members) are exposed in the sheet conveying direction. For energization of the heating resistance layer, 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 part so as to cover all of the heat generating resistance layer, the aluminum layer, the wiring and the like. The protective layer is formed of, for example, Si3N4.

  FIG. 5 is a layout view of the heat generating member group in the present embodiment. As shown in the figure, on the ceramic substrate 361a, heat generating members 361b each having a plurality of lengths in the horizontal direction in the drawing and formed in a parallelogram or a trapezoid are arranged side by side. Electrodes 361c and 361d are formed at both ends of 361b in the sheet conveying direction (the vertical direction in the drawing).

  As shown in FIG. 5, the heat generating member 361b is divided into a plurality of parts, but as will be described later, these are driven by a heat generating member unit or a heat generating member group unit (block unit) by a DC or AC applied voltage. However, for example, in the case of a high voltage (100 V or more) with an alternating current or a large amount of current even with a direct current, it is necessary to secure a sufficient creeping distance or space distance between the adjacent heat generating members 361b as a safety measure. Creepage distance is the shortest distance along the surface of an insulator between two conductive parts. In contrast, the spatial distance is the shortest distance through the space between two conductive parts. However, if these distances are made too long, the temperature will drop at the boundary.

  Therefore, in the present embodiment, the shape of each heat generating member 361b is changed in order to adjust the creepage distance or the spatial distance at the boundary between the adjacent members to a predetermined optimum value while suppressing the temperature decrease. Specifically, in the case of FIG. 5, the heat generating member 361b has a parallelogram or trapezoidal upper surface, and electrodes 361c and 361d are formed on the upper side and the lower side, respectively. Therefore, the side surfaces located at the boundary between the heat generating members 361b adjacent to each other are inclined at a predetermined angle with respect to the sheet conveying direction, and the facing side surfaces are parallel to each other. Therefore, the creeping distance between the electrodes 361c and 361d between the adjacent heat generating members 361b can be increased as compared with the case where the heating members 361b are divided in parallel to the sheet conveying direction.

  Further, as shown in FIG. 5, in the present embodiment, the heat generation pattern of the heating member 361 is composed of a plurality of types of heat generation members 361b corresponding to the size of the paper through which the length in the left-right direction in the drawing is passed. ing. Specifically, 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) ( The heating element) 361b is divided. The heat generating member group including the adjacent heat generating members 361b has a margin of about 5% or about 10 mm with respect to the heating region in consideration of the conveyance accuracy of the conveyed sheet, skew, and heat escape to the non-heated portion. To be energized.

  For example, in order to correspond to the minimum postcard size width of 100 mm, the first heating member group is provided in the central portion in the main scanning direction (the horizontal direction in the drawing), and the width thereof is 105 mm. In order to support the next larger sizes of 121 mm and 148 mm, a second heat generating member group having a width of 50 mm is provided outside the first heat generating member group (left and right direction in the drawing) to cover a width of 148 mm + 5% up to 155 mm. In order to accommodate larger sizes of 182 mm and 210 mm, a third heating member group having a width of each heating member of 65 mm is provided further outside the second heating member group to cover a width up to 220 mm at 210 mm + 5%. .. It should be noted that the number of divisions of the heat generating member group and the width of each are given as an example, and the present invention is not limited to this. For example, when the MFP 10 is compatible with five medium sizes, the heat generating member group may be divided into five according to each medium size.

  Further, 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. The paper size may be determined based on the image data or the information of the paper feed cassette 18 in which the paper is stored in the MFP 10 at the start of the printing operation.

  FIG. 6 is a cross-sectional view illustrating the creepage distance between the heat generating members 361b after the division. FIG. 6A is a cross-sectional view in the longitudinal direction of the heat generating member 361b which is not divided. Here, the case where only one heat generating member 361b having a thickness D1 is fixed on the ceramic substrate 361a which is an insulating layer is shown. Further, FIG. 6B shows a case where the heat generating member 361b is divided into a plurality while maintaining the thickness of the heat generating member 361b at D1. As in the case of FIG. 6A, the heat generating member 361b (heat generating layer) is fixed on the ceramic substrate 361a. Since the heat generating member 361b (heat generating layer) is a conductor, D1 does not affect the creepage distance. Since the boundary portion is insulated, when the spatial distance between the adjacent heat generating members 361b is G1, the creepage distance is G1. On the other hand, FIG. 6C shows the pattern of the heating member 361 in this embodiment. The thickness of the heat generating member 361b (heat generating layer) is D1 and is the same as in the case of FIGS. 6A and 6B. A block-shaped ceramic substrate 361a 'is provided. The upper surface of the ceramic substrate 361a 'has the same shape as the lower surface of the divided heat generating member 361b. Since the ceramic substrate 361a 'having the thickness D2 is separately provided, the spatial distance between the adjacent heat generating members 361b is G2, which is shorter than G1, but the creepage distance is 2 × D2 + G2. That is, it is shown that, instead of shortening the spatial distance, adjusting the creepage distance to be long, while suppressing the temperature drop at the boundary portion, simultaneously taking safety measures.

  FIG. 7 is a diagram showing a connection state of the heat generating member group and its drive circuit. As shown in the figure, the heating members 361b are controlled by the corresponding driving IC 151 individually or in groups in symmetrical positions with respect to the central portion. The heat generating members 361b are connected in parallel as a whole so that the same potential is applied to each of them, but the pair of heat generating members 361b located symmetrically with respect to the central portion are included in the parallel circuit. They are connected in series and are drive-controlled by the same drive IC 151. Since the number of drive ICs 151 can be made smaller than the number of divisions of the heat generating member 361b, the number of drive ICs 151 can be reduced, and the device size and manufacturing cost can be suppressed.

  Specific examples of the drive IC 151, which is a switching unit for energizing each heat generating member 361b, include a switching element, a FET, a triax, a switching IC, and the like. In FIG. 7, a voltage is applied to each of the heat generating members 361b by alternating current to generate heat, but it may be changed to direct current.

  For example, when the paper P has the minimum size (postcard size), only the driving IC 151 of the heat generating member 361b (first heat generating member group) arranged in the center is turned on and heated. As the size of the paper P increases, the drive ICs 151 of the second heat generating member group and the third heat generating member group are also controlled to be turned on sequentially. It is assumed that the electric resistance values of the first to third heat generating member groups are adjusted so that the temperature rising rates are uniform.

  Further, in FIG. 7, since the current supplied from the power source is divided into four and flows, the safety element 152 is provided for each parallel circuit as in the drive IC 151. When the temperature detection result of the temperature detection member 362 (not shown) that measures the surface temperature of the corresponding heat generating member 361b is “abnormal temperature detection”, the safety element 152 controls the drive IC 151 to operate the electric circuit. It is an element that cuts off.

  Hereinafter, a printing operation of the MFP 10 configured as described above will be described with reference to the drawings. FIG. 8 is a flowchart showing a specific example of control of the MFP 10 in this 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 (Act102), the electrostatic latent image is written on the surface of the photosensitive drum 22 (Act103), and the electrostatic latent image is developed by the developing device 24. (Act 104), the process proceeds to Act 114.

  When the fixing temperature control process is started, the sheet size is determined based on, for example, a detection signal from a line sensor (not shown) and the sheet selection information from the operation unit 14 (Act 105), and the sheet P passes through the position (passage). A heat generating member group arranged in the paper region) is selected as a heat generating target (Act 106).

  Next, when the temperature control start signal for the selected heat generating member group is turned on (Act 107), the selected heat generating member group is energized and the surface temperature of the heat generating member group rises. That is, when the heating region is determined, all the selected heat generating members 361b are operated under the same control. At this time, the energized heat generating member 361b generates heat at a uniform rate of temperature increase.

  Next, when the surface temperature of the heat generating member group is detected by a temperature detecting member (not shown) arranged 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 or not. It is determined whether or not (Act109). Here, when it is determined that the surface temperature of the heat generating member group is within the predetermined temperature range (Act109: Yes), the process proceeds to Act110. 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 (Act109: No), the process proceeds to Act111.

  In Act111, it is determined whether the surface temperature of the heat generating member group exceeds a predetermined temperature upper limit value. Here, when it is determined that the surface temperature of the heat generating member group exceeds the predetermined temperature upper limit value (Act111: Yes), the power supply to the heat generating member group selected in Act106 is turned off (Act112), Return to Act 108. 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 (Act111: No), it is determined that the surface temperature is less than the predetermined temperature lower limit value based on the determination result of Act109. Therefore, the energization to the heat generating member group is maintained in the ON state or turned on again (Act113), and the process returns to Act108.

  Next, when the surface temperature of the heat generating member group is within a predetermined temperature range, the sheet P is conveyed to the transfer portion (Act110). After the toner image is transferred to the sheet P (Act114), the sheet P is fixed to the fixing device. It is transported to the inside of 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 the image data printing process is to be ended (Act 116). Here, when it is determined that the printing process is to be ended (Act116: Yes), the power supply to all the heat generating member groups is turned off (Act117), and the process is ended. On the other hand, when it is determined that the image data printing process is not yet finished (Act116: No), that is, when the image data to be printed remains, the process returns to Act101 and the same process is repeated until it is finished. ..

  As described above, according to the present embodiment, by switching the heat generating member group that is the target of heat generation based on the group to which the used paper size belongs, it is possible to prevent abnormal heat generation in the non-paper passing portion, and It is possible to suppress unnecessary heating of the portion. Therefore, it is possible to significantly reduce the thermal energy consumed by the fixing device 36. Further, the creepage distance between the electrodes formed at both ends, the creepage distance or the spatial distance at the boundary between the adjacent heat generating members 361b are adjusted so that the temperature does not drop at the boundary, and thus the creepage distance at the boundary is reduced. It is possible to take safety measures at the same time while suppressing the temperature decrease. As a result, the temperature unevenness of the heating member 361 in the paper passing area is eliminated, and the fixing quality can be improved.

<Modification>
Hereinafter, some modified examples of the above embodiment will be described in detail with reference to the drawings.
FIG. 9 is a cross-sectional view showing a fixing structure of the heat generating member 361b and the ceramic substrate 361a in the modification of the above embodiment. Here, the upper surface of the ceramic substrate 361a to which the plurality of heat generating members 361b are fixed is formed in a curved shape, and the creeping distance and the spatial distance are adjusted by the angle of curvature on the upper surface and the fixing position of each heat generating member 361b. It is shown. As shown in FIG. 9, since a plurality of heat generating members 361b are fixed on the curved surface of the crown-shaped ceramic substrate 361a, the spatial distance at the boundary between the adjacent heat generating members 361b becomes short, but the creeping surface is reduced by that amount. The distance can be increased. Each heating member 361b may be independently patterned and attached to the ceramic substrate 361a, or may be formed by the method of simultaneously forming the pattern of the resistance heating layer on the ceramic substrate 361a as described above.

  10 and 11 are diagrams showing other shape patterns of the heat generating member group in the modified example of the above embodiment. In FIG. 10, the boundary portion between the adjacent heat generating members 361b is formed into a bent shape, and the surfaces facing each other at the boundary portion are formed to be parallel to each other, whereby the creepage distance between the electrodes 361c and 361d is adjusted. It has been shown that

  Further, when different size sheets are conveyed and printed during continuous printing (especially, when printing from a small size sheet to a larger size sheet), a heat generating member that generates heat corresponding to the sheet size. In order to secure a time until the temperature detection result of the temperature detection member 362 related to 361b becomes the same among the members, it is preferable to control the fixing control program so as to extend the paper conveyance interval or delay the conveyance speed. Is.

  Further, if the length of the heat generating member 361b after the division is adjusted so that the boundary portion is located outside the end portion of the sheet passing area, the influence from the boundary portion can be suppressed, which is preferable.

  Further, in the above-described embodiment, the size of the paper passing area of the paper P is determined based on the paper setting information before the paper P is conveyed into the fixing device 36. Alternatively, the position where the print region (image forming region) passes can be determined and heating can be performed. As a method of determining the size of the printing area of the paper P, a method of using the analysis result of the image data, a method based on print format information such as a margin setting for the paper P, and a method of determining based on the detection result of the optical sensor are used. And so on. In this case, since it is possible to heat only the portion where fixing is necessary, the energy saving efficiency can be further improved.

  On the other hand, FIG. 11 shows the case where the rectangular heat generating member 361b is fixed on the ceramic substrate 361a so as to be inclined at a constant angle with respect to the sheet conveying direction indicated by the arrow A. When the heat generating member 361b is formed in a parallelogram or trapezoidal shape as shown in FIG. 5, the current flows through the member in the shortest distance, and therefore, depending on the size of the heat generating member 361b, even within the same heat generating member 361b. Differences occur in the ease of heat generation. Therefore, as shown in FIG. 11, a rectangular heat generating member 361b having the same distance between the electrodes 361c and 361d is arranged so as to be inclined with respect to the sheet conveying direction, so that the energization condition and the heat generation condition are made uniform. You can

  Although the embodiment of the present invention has been described above, the present embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. This 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 the scope of equivalents thereof.

36 ... Fixing device 150 ... Fixing control circuit 151 ... Driving IC
361 ... Heating member 361a ... Ceramic substrate 361b ... Heating members 361c, 361d ... Electrode 363 ... Endless belt 366 ... Pressure roller

Claims (6)

An insulator,
A plurality of heat generating members arranged on the surface of the insulator, divided in a direction perpendicular to the medium transport direction, and each of which is energized to heat the medium;
Equipped with
A creeping distance of the insulator between the plurality of heat generating members is longer than a distance between the plurality of heat generating members. Further comprising a plurality of electrodes for energization arranged at both ends of each of the plurality of heat generating members in the transport direction,
The side spaces between the plurality of electrodes, which is inclined at a predetermined angle to the side surface of the heat generating member located in the boundary portion between the heat-generating member adjacent to the conveying directions, facing in the boundary portion The heating member according to claim 1, which is adjusted by forming the members to be parallel to each other. Further comprising a plurality of electrodes for energization arranged at both ends of each of the plurality of heat generating members in the transport direction,
Space between the plurality of electrodes is configured to the side surface of the bent shape of the heat generating member located in the boundary portion between the heat-generating member adjacent to each other, such that the side surfaces facing each other in the boundary portion are parallel The heating member according to claim 1, which is adjusted by forming the heating member. A selective heating device that selectively energizes a heat generating member corresponding to a position where the medium passes among the plurality of heat generating members to heat the medium,
The heating member according to claim 1, further comprising: A first insulator formed along a direction perpendicular to the medium transport direction;
A plurality of second insulators arranged along the direction on the first insulator,
A plurality of heat generating members that are respectively disposed on any of the plurality of second insulators and that are selectively energized to generate heat and heat the medium;
A heating member. A transfer belt that moves in one direction,
A photoconductor that is arranged along the moving direction of the transfer belt and holds an electrostatic latent image on the surface,
A developing device which is disposed so as to face the photoconductor, and adheres the discharged toner to the electrostatic latent image to form a toner image on the photoconductor;
A transfer member that is pressed against the photoconductor through the transfer belt based on the supply of a transfer voltage and transfers the toner image formed on the photoconductor onto the transfer belt;
A fixing device for fixing the toner image on the transfer belt to a medium by applying pressure and heat;
A heating member for heating the medium in the fixing device;
Equipped with
The heating member is
A first insulator formed along the longitudinal direction of the heating member perpendicular to the medium transport direction;
A plurality of second insulators arranged along the longitudinal direction on the first insulator,
A plurality of heat generating members that are respectively disposed on any of the plurality of second insulators and that are selectively energized to generate heat and heat the medium;
An image forming apparatus including.

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