JP6978856B2 - Heater and fixing device - Google Patents

Description

The present embodiment relates to a heater and a fixing device.

In recent years, in a fixing device using a resistance heating element, it has been studied to arrange a heat generating portion in which a heat generating region is divided into a plurality of parts in the main scanning direction and selectively generate heat in the heat generating region corresponding to the paper size. However, when the heat generating region of the resistance heating element is divided, there is a problem that the temperature drops at the connecting portion between the adjacent regions.

In the fixing device for electrophotographic, if heat generation unevenness occurs in the direction perpendicular to the paper transport 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 may occur.

Japanese Unexamined Patent Publication No. 2015-028531

Therefore, it is an object of the present invention to provide a heater and a fixing device capable of preventing a temperature drop in a connecting portion between adjacent regions when the heating region of the resistance heating element is divided.

The heater according to the embodiment is provided on the heat generating portion generated by energization and on the opposite side edges of the heat generating portion so as to be electrically connected to the heat generating portion, and at least one of them is separated by cutting out a part thereof. comprising a plurality of electrodes formed, wherein the heating unit includes a groove to separate the position of the side edges of the plurality of electrodes, that have a shape provided continuously in the main scanning direction It is characterized by that.

The figure which shows the structural example of the image forming apparatus using the fixing apparatus which concerns on one Embodiment. The block diagram which shows the part of the image forming part in one embodiment enlarged. The block diagram which shows the configuration example of the control system of the MFP in one Embodiment. The figure which shows the structural example of the fixing device which concerns on one Embodiment. The top view which shows the arrangement of the heat generating part and the electrode on the insulator substrate in one Embodiment. The figure which shows the feeding structure to the heat generating part of one Embodiment shown in FIG. An enlarged view of the broken line area A in FIG. Explanatory drawing for consideration of the mechanism of the cause that the decrease of heat between heat generation regions is suppressed. Another explanatory diagram for consideration of the mechanism of the cause of suppressing the decrease in heat between the heat generation regions. Top view of the embodiment in which the groove portion of the heat generating portion is U-shaped. Top view of the embodiment in which the groove portion of the heat generating portion is V-shaped. Top view of an embodiment having no groove. Top view of an embodiment in which the depth of the groove is different. Top view of an embodiment having one notch on the common electrode side. Top view of an embodiment having one notch and one groove on the common electrode side. Top view of an embodiment having a plurality of notches and a plurality of grooves on the common electrode side. Top view of another embodiment having a plurality of notches and a plurality of grooves on the common electrode side. The figure which shows the structural example of the fixing device which concerns on other embodiment.

<Configuration example of image forming apparatus>
The present invention exists, for example, as shown in FIG. 7, between a plurality of individual electrodes 361d1, 361d2 and the like provided on the side edges of the rectangular heat generating portion 361 and a heat generating region generated by energization between the common electrodes 361c. It is a heater or the like that suppresses a temperature drop in the region where the temperature drops.

FIG. 1 is a diagram showing a configuration example of an image forming apparatus using the fixing apparatus according to the first embodiment. In FIG. 1, the image forming apparatus is, for example, an MFP (Multi-Function Peripherals) which is a multifunction device, a printer, a copying machine, or the like. In the following description, the MFP 10 will be described as an example.

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

A scanner unit 15, which is a reading device, is provided at the lower part of 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 the document table to generate image data, and includes a close contact type image sensor 16. The image sensor 16 is arranged in the direction in which the main scan is performed on the document, that is, in the main scan direction, that is, in the depth direction in FIG. 1, and is moved in the arrow S direction to perform the sub scan.

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

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

The printer unit 17 processes the image data read by the scanner unit 15 and the 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 color laser printer, and includes image forming units 20Y, 20M, 20C, and 20K of each color of yellow (Y), magenta (M), cyan (C), and black (K). The image forming portions 20Y, 20M, 20C, and 20K are arranged in parallel on the lower side of the intermediate transfer belt 21 from the upstream side to the downstream side. Further, 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 an enlarged view of 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 unit 20K has a photoconductor drum 22K which is an image carrier. A charger 23K, a developing device 24K, a primary transfer roller (transfer device) 25K, a cleaner 26K, a blade 27K, and the like are arranged around the photoconductor drum 22K along the rotation direction t. The exposure position of the photoconductor drum 22K is irradiated with light from the scanning head 19K 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 developer 24K supplies a two-component developer containing black toner and carriers to the photoconductor drum 22K by a developing roller 24a to which a developing bias is applied to develop an 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, 24M, 24C, 24K is provided above the image forming units 20Y, 20M, 20C, 20K. The toner cartridge 28 includes toner cartridges 28Y, 28M, 28C, 28K 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 on the drive roller 31 and the driven roller 32. Further, the intermediate transfer belt 21 is in contact with the photoconductor drums 22Y, 22M, 22C, 22K facing each other. A primary transfer voltage is applied to the position of the intermediate transfer belt 21 facing the photoconductor drum 22K by the primary transfer roller 25K, and the toner image on the photoconductor drum 22K is primarily transferred to the intermediate transfer belt 21.

The secondary transfer roller 33 is arranged to face the drive roller 31 on which the intermediate transfer belt 21 is stretched. When the paper P passes between the drive roller 31 and the secondary transfer roller 33, the 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 paper P. A belt cleaner 34 is provided in the vicinity of the driven roller 32 of the intermediate transfer belt 21.

Further, as shown in FIG. 1, between the paper feed cassette 18 and the secondary transfer roller 33, a paper feed roller 35 for transporting the paper P taken out from the paper feed cassette 18 is provided. 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 the paper ejection unit 38. Further, a reverse transfer path 39 is provided downstream of the fixing device 36. The reverse transfer path 39 reverses the paper P and guides it in the direction of the secondary transfer roller 33, and is used when performing double-sided printing. 1 and 2 show an example of an embodiment of the present invention, and do not limit the structure of the image forming apparatus portion other than the fixing apparatus 36, and use a known electrophotographic image forming apparatus structure. Can be done.

<Configuration example of control system of MFP10>
FIG. 3 is a block diagram showing a configuration example of the control system 50 of the MFP 10 in one 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, and a paper feed / transfer control circuit. It includes 130, an image formation 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 RAM 121) stores, for example, control programs such as the image forming unit 20 and the fixing device 36, and various control data used by the control programs. As a specific example of the control data in the present embodiment, the size of the print area in the paper, that is, the width in the main scanning direction in which the document is mainly scanned (the first, second, and third medium sizes in FIG. 5, which will be described later). ) And the heat-generating part that is the target of power supply.

The fixing temperature control program of the fixing device 36 has a determination logic for determining the size of the image forming region on the paper on which the toner image is formed, and the image forming region passes through the paper before the paper is conveyed to the inside of the fixing device 36. It includes a heating control logic that selects and feeds the switching element of the heat generating portion corresponding to the position and controls the heating in the heating means.

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 123b. The paper feed / transport control circuit 130 controls the motor group 130a or the like that drives the paper feed roller 35 or the transport roller 37 of the transport path. The paper feed / transport control circuit 130 controls the motor group 130a and the like based on the control signal from the CPU 100 in consideration of the detection results of various sensors 130b in the vicinity of the paper feed cassette 18 or on the transport path.

The image formation control circuit 140 controls the photoconductor drum 22, the charger 23, the scanning head 19, the developer 24, and the transfer device 25, respectively, based on the control signal from the CPU 100. The fixing control circuit 150 controls temperature detection members such as a drive motor 360, a heat generating unit 361, and a thermistor of the fixing device 36 based on a control signal from the CPU 100. In the present embodiment, the control program and control data of the fixing device 36 are stored in the storage device of the MFP 10 and executed by the CPU 100, but a calculation processing device and a storage device are separately provided for the fixing device 36. You may.

<Structure example of fixing device 36>
FIG. 4 is a diagram showing a configuration example of the fixing device 36. Here, the fixing device 36 is attached to a plate-shaped heat generating portion 361, an endless belt 363 on which an elastic layer is formed and suspended on a plurality of rollers, a belt transport roller 364 for driving the endless belt 363, and an endless belt 363. A tension roller 365 for applying tension and a press roller 366 having an elastic layer formed on the surface thereof are provided.

In the heat generating portion 361, the heating portion side comes into contact with the inside of the endless belt 363 and is pressed in the direction of the press roller 366 to form a fixing nip having a predetermined width between the heat generating portion 361 and the press roller 366. Since the heat generating portion 361 heats while forming the nip region, the responsiveness at the time of feeding is higher than that in the case of the heating method using the halogen lamp.

In the endless belt 363, for example, a silicon rubber layer having a thickness of 200 μm is formed on the outer side of a SUS substrate having a thickness of 50 μm or a polyimide which is a heat-resistant resin of 70 μm, and the outermost periphery thereof is covered with a surface protective layer such as PFA. .. In the press roller 366, for example, a silicon sponge layer having a thickness of 5 mm is formed on the surface of an iron rod having a diameter of 10 mm, and the outermost periphery thereof is covered with a surface protective layer such as PFA.

<Structure of heat generating part>
Further, in the heat generating portion 361, for example, a heat generation resistance layer, a glaze layer, and a heat generation resistance layer are laminated on an insulator such as a ceramic substrate. The glaze layer may not be present. The heat generation resistance layer is formed of a known material such as _{TaSiO 2.} The heat generation resistance layers have a predetermined length in the main scanning direction in which the document is mainly scanned, and are provided in a predetermined number.

The method of forming the heat generation resistance layer is the same as that of a known method, for example, a method of forming a thermal head. For example, a masking layer (electrode layer) is formed of aluminum on the heat generation resistance layer. This masking layer has a pattern in which a heat generating portion (resistance heating element) is exposed in the paper transport direction. This pattern separates the thermal regions.

The power supply to the heat generating part is connected from the aluminum layers (electrodes) at both ends by a conductor (wiring), and each is connected to the switching element of the switching driver or the like.

Further, a protective layer is formed at the uppermost portion so as to cover all of the resistance heating element, the aluminum layer, the wiring and the like. The protective layer is formed of, for example, SiO ₂ or Si ₃ N ₄ or the like. When supplying AC or DC to such a group of heat generating parts, power is supplied to the portion to be generated by the triac or FET with zero cross, and flicker is also taken into consideration.

<Relationship between heat generating part and electrode, when the shape of the groove part is rectangular (concave)>
FIG. 5 is a top view showing the relationship between the heat generating portion, the common electrode, and the individual electrode in one embodiment. A heat generating portion 361b, a common electrode 361c, and an individual electrode 361d are provided on the insulator substrate 361a.

Here, the heat generation region (heat generation region 361b) of the heat generation unit 361 has a width of a postcard size (100 × 148 mm), a CD jacket size (121 × 121 mm), a B5R size (182 × 257 mm), and an A4R size (210 × 297 mm). In order to correspond to, the electrode on the electrode side at one end is divided into, for example, five by a notch portion described later in the main scanning direction (arrow MA) for main scanning of the document, and constitutes an individual electrode 361d. ..

At one end (side edge) of the heat generating portion in the sub-scanning direction (arrow SU direction), four groove portions 361 m are formed in a rectangular shape as recesses. The individual electrode 361d is formed at a position of one end of the heat generation region 361b in the transport direction of the medium, excluding the plurality of groove portions 361m. That is, the notched portion of the electrode (notch portion 361d0) corresponds to the groove portion of the heat generating portion.

FIG. 6 is a circuit diagram showing a power feeding structure to the heat generation region 361b in one embodiment. Here, a parallel power feeding structure is shown in which the heat generation region of the heat generation region 361b is individually controlled to be energized by the corresponding five switches 361e.

Specifically, the switch 361e is individually composed of 361e1, 361e2, 361e3, 361e4, 361e5. The individual electrode 361d is composed of 361d1, 361d2, 361d3, 361d4, 361d5. Specific examples of the drive IC indicated by the switch 361e include switching elements, FETs, triaxes, switching ICs, and the like.

FIG. 7 is an enlarged view of the broken line region A shown in FIG. Here, the groove portion 361 m is formed with the length (width) of the main scanning direction (arrow MA) of the document being x and the length (depth) of the sub-scanning direction (arrow SU direction) being y.

The aspect ratio of x and y can be arbitrarily changed and is determined by measuring the in-plane temperature distribution of the connecting portion of the heat generation region. For example, x: y = 1: 1 or x: y = 2: 3.

As will be described later, the values of the sizes x and y of the groove portion 361 m do not have to be the same, and the value of y (depth) may be changed according to the position of the groove portion 361 m, for example (the embodiment of FIG. 13). See).

In FIG. 6, one end of the power supply 362 is connected to the common electrode 361c, and switches 361e1 to 361e5 are connected in parallel to the other end of the power supply. Individual electrodes 361d1-661d5 are connected to each of these switches 361e1 to 361e5. For example, when the switch 361e2 is turned on and a current is passed through the heat generation region 361b by the power supply 362 between the individual electrodes 361d2 and the common electrode 361, the heat generation region 361b2 is generated.

Similarly, when a current is passed through the heat generating portion 361 by the power supply 362 between the individual electrodes 361d1 and the common electrode 361c, a heat generating region 361b1 is generated.

Between the heat generation region 361b2 and the heat generation region 361b1, a portion having a lower temperature than the heat generation region is generated. This is because there is a notch portion and a groove portion 361m of the electrode between the individual electrode 361d2 and the individual electrode 361d1. However, since the heat-generating portion is continuous in the portion where the temperature is low between the heat-generating regions, the temperature does not drop as much as when the heat-generating portion is cut off.

In this way, this temperature decrease is suppressed between the heat generation regions. The mechanism is inferred next.

<Mechanism of suppressing temperature drop between heat generation regions>
According to the present embodiment, the heat generating region of the heat generating portion 361b is divided into a plurality of heat generating portions, but the heat generating portion is continuous between the adjacent heat generating regions. Therefore, among the adjacent heat generation regions, even when power is not supplied to one of the heat generation regions corresponding to the medium size, the region between the heat generation regions (connected region) also generates heat to some extent.

There are two possible mechanisms for this. One is the conduction of heat from adjacent heat generating regions as shown in FIG. The other one is heat generation due to energization between the adjacent individual electrodes and the common electrode as shown in FIG. Now, in FIG. 7, specifically, it is considered to suppress the temperature decrease in the connecting region between the heat generation region 361b2 and the heat generation region b1.

The heat conduction from the former heat generation region is considered as shown in FIG. When the heat generating portion 361b between the individual electrode 361d2 and the common electrode 361c is energized, the heat generating region 361b2 generates heat and the temperature rises. It is considered that the heat itself generated by the heat generated by the heat generation region 361b2 is also transmitted to the connecting region as shown by the arrow H1. This is because the heat generating portion 361b, which is a heat conductor, is continuous. Similarly, when the heat generation region 361b1 is generating heat, it is considered that the heat is also transferred to this connection region as shown by the arrow H2.

On the other hand, heat generation due to energization between the adjacent individual electrode and the common electrode is considered as follows. For example, in FIG. 8, it is assumed that the individual electrode 361d1 is also energized together with the individual electrode 361d2.

That is, it is assumed that the common electrode 361c and the individual electrode 361d2 are energized via the heat generating portion 361b, and the common electrode 361c and the individual electrode 361d1 are also energized.

In this case, as described above, the heat generation region 361b2 is formed by energization between the common electrode 361c and the individual electrode 361d2. On the other hand, the heat generation region 361b1 is formed by energization between the common electrode 361c and the individual electrode 361d1. In this case, a current may flow through the heat generating portion 361b not only in the direction of arrow C22 but also in the direction of arrow C21.

On the other hand, the heat generation region 361b1 is formed by energization between the common electrode 361c and the individual electrode 361d1. In this case, a current may flow through the heat generating portion 361b not only in the direction of arrow C11 but also in the direction of arrow C12.

It is possible that both of the above two mechanisms are working. Alternatively, other mechanisms may suppress the temperature drop in the regions between the exothermic regions. In any case, the temperature drop between the heat generation regions is suppressed. The same effect can be obtained regardless of the shape of the groove portion, and when there is no groove portion and only the notch portion of the electrode is present.

As described above, as compared with the structure in which the heat generating regions are physically separated when the medium size is switched, it is possible to suppress the temperature drop in the connected portion.

<Other shapes of the groove>
In this embodiment, the case where the groove portion 361 m has a rectangular shape (concave shape) has been described. However, the groove may be formed in another shape, for example, a U-shape or a V-shape. Further, the groove portion 361 m has a structure that penetrates the heat generating portion 361 in the vertical direction (direction penetrating the paper surface in FIG. 5), but the embodiment as a recess is not limited to this. For example, the structure may be such that the heat generating portion 361 is drilled halfway in the thickness direction (vertical direction), and the remainder may not be drilled.

FIG. 10 shows an enlarged top view of the embodiment in which the shape of the groove portion of the heat generating portion is U-shaped. In this embodiment, a common electrode 361c is provided on one of the opposite side edges of the rectangular heat generating portion 361b that generates heat by energization. On the other side of the side edge, a notch portion of the individual electrodes 361d1 and 361d2 and a U-shaped groove portion 361u are provided at the corresponding positions thereof.

According to the embodiment in which the groove portion has a U-shape, the heat generating portion has no corner and the current is less likely to be locally concentrated as compared with the embodiment in which the groove portion has a rectangular shape. Therefore, there is an advantage that a current can flow relatively uniformly even in the vicinity of the groove portion and stable heat generation can be performed.

FIG. 11 shows an enlarged view of an embodiment in which the shape of the groove portion of the heat generating portion is V-shaped. In this embodiment, a common electrode 361c is provided on one of the opposite side edges of the rectangular heat generating portion 361b that generates heat by energization. On the other side of the side edge, a notch portion of the individual electrodes 361d1 and 361d2 and a V-shaped groove portion 361v are provided at the corresponding positions thereof.

According to the embodiment in which the groove is V-shaped, the groove is gradually enlarged as compared with the embodiment in which the groove is rectangular. Therefore, since the influence on the heat generating portion of the groove portion is small, there is an advantage that the current flows relatively uniformly even in the portion having the groove portion and stable heat generation can be performed.

<When there is no groove in the heat generating part>
In the above description, the case where the groove portion is provided corresponding to the notch portion of the electrode has been described. However, if there is a notch portion of the electrode, a structure having no groove portion may be used. An enlarged top view of such an embodiment is shown in FIG.

In this embodiment, a common electrode 361c is provided on one of the opposite side edges of the rectangular heat generating portion 361b that generates heat by energization. The other side of the side edge has individual electrodes 361d1, 361d2, 361d3 and the like. It has a notch 361d0 between these individual electrodes, but does not have a groove at a position corresponding to the notch 361d0.

In the embodiment of this structure, there is a notch portion of the electrode, but since there is no groove portion in the heat generating portion, there is no constriction, and there is an effect that the temperature drop between the heat generating regions can be suppressed to the minimum.

<When the depth of the groove changes>
In the above-described embodiment, the embodiment in which the shape of the groove portion, that is, the width (x) and the depth (y) of the groove portion are the same has been described.

However, it is also possible to have a structure in which the groove portion does not have the same shape and the width and depth thereof are changed depending on the position where the groove portion is provided. FIG. 13 shows an embodiment in which the depth y of the groove portion is changed.

In this embodiment, a common electrode 361c is provided on one of the opposite side edges of the rectangular heat generating portion 361b that generates heat by energization. The other side of the side edge has individual electrodes 361d1, 361d2, 361d3 and the like. A notch 361d0 and a corresponding groove are provided between these individual electrodes. These grooves are 361 m1,361 m2, 362 m3, 361 m4.

It is the same as the embodiment shown in FIG. 6, except that the depths of the grooves are not the same. FIG. 13 is a circuit diagram showing a power feeding structure to the heat generating portion 361b in one embodiment. Here, a parallel power feeding structure is shown in which the heat generation region of the heat generation unit 361b is individually controlled to be energized by the corresponding five switches 361e.

Specifically, the switch 361e includes switches 361e1, 361e2, 361e3, 361e4, 361e5. The individual electrode 361d is composed of 361d1, 361d2, 361d3, 361d4, 361d5.

A rectangular groove portion 361 m1 having a depth of y1 is provided corresponding to the notch portion 361d0 between the individual electrodes 361d1 and the individual electrodes 361d2. A rectangular groove portion 361 m2 having a depth of y2 is provided corresponding to the notch portion 361d0 between the individual electrodes 361d2 and the individual electrodes 361d3. A rectangular groove portion 361 m3 having a depth of y2 is provided corresponding to the notch portion 361d0 between the individual electrodes 361d3 and the individual electrodes 361d4. A rectangular groove portion 361 m4 having a depth of y1 is provided corresponding to the notch portion 361d0 between the individual electrodes 361d4 and the individual electrodes 361d5.

The shape of the groove portion is not limited to a rectangular shape, and may be another shape such as a U-shape or a V-shape.

According to the embodiment having the grooves having different depths, there is an effect that it is possible to adjust the heat imbalance between the end portion and the center of the heat generating portion.

Further, it is also possible to have an embodiment in which not only the depth of the groove but also the width (x) of the groove is changed, or the depth and the width are changed in combination.

<When there are notches and grooves on the common electrode side>
In the above embodiment, the common electrode 361c is provided on one side edge of the rectangular heat generating portion 361b. In the present invention, the common electrode on the side edge may be changed to an individual electrode by providing a notch. The number of notches may be the same as or different from the number of individual electrodes on the other side edge. Such an embodiment of the present invention includes an embodiment in which a groove portion of a heat generating portion is provided and an embodiment in which a groove portion is not provided.

FIG. 14 shows an embodiment in which the common electrode is divided into two common electrodes 361c1 and 361c2 by a notch 3611d0. In this embodiment, the groove portion is not provided on the common electrode side.

The common electrode 361c1 is connected to the power supply 362 to which the switch 361f1 is connected. The common electrode 361c2 is connected to the power supply 362 to which the switch 361f2 is connected. The common electrodes 361c1 and 361c2 may be collectively referred to as a common electrode 361c. The switches 361f1 and 361f2 may be collectively referred to as a switch 361f.

In this embodiment, the common electrode is divided into two, and by selectively turning on the switches 361f1 and 361f2, it is possible to change the main heat generation region on the common electrode side.

FIG. 15 shows an embodiment in which the common electrode is divided into two and has a notch portion 361d0 and a groove portion 361n0 at a position corresponding to the notch portion.

This embodiment has a groove portion 361n0 at a position corresponding to a notch portion 361d0 between the common electrode 361c1 and the common electrode 361c2. Other than this point, it is the same as the embodiment of FIG. 14, and is shown using the same reference numerals as those of FIG.

Also in this embodiment, the common electrode is divided into two, the switch 361f1, 361f2 is selectively turned on, and the switch to which the individual electrodes 361d (361d1,361d2, 361d3, 361d4, 361d5) are connected is connected. By selectively turning it on, it is possible to change the heat generation region.

In this embodiment, since the groove portion 361n0 is provided, it is possible to facilitate the selection of the heat generation region on the common electrode side as compared with the case of the embodiment of FIG.

FIG. 16 shows an embodiment in which the number of individual electrodes on both side edges is the same (five in this example) and the positions where the grooves are provided are the same. The method of assigning a reference numeral to each part is the same as in the case of FIG. By selectively turning on the switch 361e and selectively turning on the switch 361f, it is possible to form a heat generating region in the heat generating portion between the electrodes on the individual electrode side and the electrodes on the common electrode side.

In the embodiment of FIG. 16, since the position of the notch portion and the position of the corresponding groove portion are the same, the heat generation region is individually selected, and there is an effect that power consumption can be reduced.

FIG. 17 shows a top view of an embodiment in which the number of individual electrodes on both side edges is the same (five in this example) and the positions where the grooves are provided are different. The method of assigning a reference numeral to each part is the same as in the case of FIG. By selectively turning on the switch 361e and selectively turning on the switch 361f, it is possible to form a heat generating region in the heat generating portion between the electrodes on the individual electrode side and the electrodes on the common electrode side.

In this embodiment, since the positions of the notch portion of the electrode and the corresponding groove portion are deviated between the individual electrode side and the common electrode side, there is an effect that the temperature drop between the heat generation regions can be suppressed.

<Other deformation examples of the groove>
The number of heat generation regions and their respective widths in FIG. 5 described above are given as an example, and are not limited thereto. When the MFP 10 corresponds to, for example, five medium sizes, the heat generation region may be divided into five according to each medium size. That is, the number of heat generation regions and the width to be divided can be freely selected according to the corresponding medium size, and heat can be uniformly generated. Similarly, the heat generation region to be fed can be selected based on the size of the print size (image forming region) instead of the medium size. Further, in the example of FIG. 5, an example in which the medium passes through the central region is shown, but when the medium passes through the left or right region in the main scanning direction (horizontal and horizontal directions in the drawing), the number and size of the heat generating regions. , The position may be changed as appropriate.

Further, in the present embodiment, 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 medium size may be determined from the image data or the information of the paper feed cassette 18 in which the medium (paper) is stored in the MFP 10 at the start of the printing operation.

<Other embodiments in which the configuration of the fixing device is different>
In the configuration example of the fixing device shown in FIG. 4 above, the heat generating portion side of the heating portion 361 is provided in contact with the inside of the endless belt 363, and is pressed in the opposite press roller 366 direction to form the endless belt 363. The toner was heated and fixed on the paper P that was sandwiched between the press rollers 366 and moved. The endless belt 363 at this time was driven by the belt transport roller 364 to which the drive motor was connected. However, it is also possible to drive the paper P from the press roller side to transfer the paper P.

FIG. 18 shows a configuration example of the fixing device of such an example. In the fixing device shown in FIG. 18, it is driven from the press roller side. A film guide 52 having an arcuate cross section is provided facing the press roller 51, and a fixing film 53 is rotatably attached to the outside thereof. A ceramic heater 54a, a plurality of heat generating portions 54b, and a protective layer 54c are laminated on the inside of the film guide 52. This laminated portion is pressed against the press roller via the fixing film to form a nip portion. As described above, the heat generating portions are connected in parallel and are connected to the temperature control circuit 55. The temperature control circuit 55 controls the opening and closing of a switching element (not shown) to control the temperature.

During the operation of this fixing device, the press roller 51 connected to the drive motor is rotationally driven to rotate the fixing film 53 in contact with the fixing film 53 in a driven manner. At this time, the paper P entering between the fixing film 53 and the press roller 51 from the left is heated and fixed by the heat generating portion 54b, and is discharged to the right.

As described above, the fixing device according to the present invention can also be a fixing device having a structure in which a driving force is applied from the press roller side.

Although the embodiments of the present invention have been described above, the present embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The present embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

10 ... MFP
36 ... Fixing device 361 ... Heat generation part 361a ... Insulator substrate 361b ... Heat generation part 361c ... Common electrode 361d ... Individual electrode 361d0 ... Notch part 361m ... Groove part

Claims (5)

A heat-generating part that generates heat when energized,
A plurality of electrodes provided on the opposite side edges of the heat generating portion so as to be electrically connected to the heat generating portion, and at least one of which is separated and formed by cutting out a part thereof.
The heater is characterized in that the heat generating portion has a groove portion at a position where the side edges of the plurality of electrodes are separated, and has a shape continuously provided in the main scanning direction. The heater of claim 1, wherein the groove is a concave shape having a front Symbol heating unit. The heater according to claim 1, wherein the groove portion of the heat generating portion has a U-shape or a V-shape. With an endless rotating body,
A heat generating portion formed in a direction orthogonal to the transport direction of the medium, arranged inside the rotating body and at a position where heat is transferred to the rotating body, and at least two facing sides are formed substantially in the transport direction. A plurality of electrodes provided on two sides of the heat generating portion in the transport direction and separated and formed by cutting out at least one of the two sides, the heat generating portion is provided on the side of the plurality of electrodes. A heater having a groove at a position where the edge is separated and having a shape continuously provided in the main scanning direction,
Fixing device with. The fixing device according to claim 4, wherein a plurality of the groove portions of the heat generating portion are provided and arranged outside the passing region of the predetermined medium.

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