JP2022019143A - Heater member, heating device, fixing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the safety of a heater member with a small number of current cutoff members or temperature detection members.
SOLUTION: A heater member 330 has a plurality of rows of resistors 332a1 to 332a4 formed in the longitudinal direction of a base material 331 and generating heat by energization, and the plurality of rows of resistors are short lengths orthogonal to the longitudinal direction of the base material. A resistance pattern 332a connected in parallel in a state of being separated from each other in the hand direction, and a heat equalizing member which is arranged across at least two rows of resistors in the short direction to reduce the temperature difference between the rows of resistors. A current cutoff member (thermostat TH) and / or a current cutoff member (thermostat TH) that is arranged on top of the 339 and the resistance temperaturemeter and cuts off the power supply to the resistance pattern when the temperature of at least two or more rows of resistors reaches the high temperature threshold. It is characterized by having a temperature detecting member (thermistor TM) for detecting the temperature of any one of at least two rows or more of resistors.
[Selection diagram] FIG. 4A

Description

The present invention relates to a heater member, a heating device, a fixing device, and an image forming device, and particularly relates to a heater member having a resistance pattern that generates heat by energization, and a heating device, a fixing device, and an image forming device using the heater member.

Various types of fixing devices used in electrophotographic image forming devices are known. One of them is a model in which a thin-walled fixing belt having a low heat capacity is directly heated by a heater member (see Patent Documents 1 to 3). The heater member is composed of a base material and a resistance pattern (plane heater). A pressure roller as a pressure member is disposed on the outside of the fixing belt, and the pressure roller sandwiches the fixing belt and presses it against the heater member to form a fixing nip.

In the fixing devices of Patent Documents 1 to 3, a plurality of resistance patterns are arranged in the longitudinal direction of the base material. Then, the first resistance pattern in the center in the longitudinal direction is energized to heat the small size paper. In addition, second resistance patterns are arranged at both ends in the longitudinal direction, and the first and second resistance patterns are simultaneously energized to heat large-sized paper.

These resistance patterns are generally formed by printing a resistance material on a ceramic substrate or the like at one time by screen printing. The area and thickness of each resistance pattern are made constant so that the resistance value (heat generation distribution) becomes uniform in the longitudinal direction of the base material. In this homogenization, the first resistance pattern in the center is wider and has a larger area than the second resistance patterns at both ends. Therefore, at least the first resistance pattern is divided into a plurality of patterns in the longitudinal direction, and these multiple patterns are divided into a plurality of patterns. I try to connect in parallel.

However, as the number of resistance patterns connected in parallel increases, it becomes difficult to control the temperature of the fixing belt and ensure safety in the event of a disconnection failure. In the fixing device of Patent Document 1 (Japanese Patent No. 6336026), the central first resistance pattern is divided into 15 in parallel, and the second resistance patterns at both ends are divided into three in parallel. Then, the temperature of the fixing belt is controlled by four thermistors, and when the temperature of the first or second resistance pattern reaches the high temperature threshold value due to a failure, the current of the heater member is cut off by the safety element arranged between the two resistance patterns. (See Fig. 3).

As can be seen from this, when the number of resistance patterns of parallel connection is large, the structure becomes complicated, it becomes difficult to cope with miniaturization, and the cost becomes high. Therefore, an object of the present invention is to ensure the safety of the heater member with a small number of current cutoff members (safety elements) or temperature detection members.

In order to solve the above problems, the heater member of the present invention has a plurality of rows of resistors formed in the longitudinal direction of the base material and generates heat by energization, and the plurality of rows of resistors are orthogonal to the longitudinal direction of the base material. The resistance patterns are connected in parallel in a state of being separated from each other in the lateral direction, and the resistors are arranged across at least two rows of the resistors in the lateral direction to reduce the temperature difference between the rows of the resistors. A current interrupting member and a current interrupting member which is arranged so as to overlap the resistance thermometer member and cuts off the power supply to the resistance pattern when the temperature of any of the at least two rows or more of the resistors reaches the high temperature threshold. / Or having a temperature detecting member for detecting the temperature of any one of the at least two rows or more of the resistors.

According to the present invention, the safety of the heater member can be ensured with a small number of current cutoff members or temperature detection members.

It is a schematic block diagram of the image forming apparatus which concerns on embodiment of this invention. It is a principle diagram of the image forming apparatus which concerns on embodiment of this invention. It is a schematic block diagram of the fixing device. It is a top view of the heater member which concerns on the basic embodiment of this invention. It is a top view of the heater member which changed the position of a thermostat and a thermistor. It is a top view of the heater member which changed the position of a thermostat and a thermistor. It is a top view of the heater member which concerns on application embodiment of this invention. It is a top view of the heater member which shows the positional relationship between a broken resistor and a thermostat / thermistor. It is a top view of the heater member which shows the positional relationship between a broken resistor and a thermostat / thermistor. It is sectional drawing which provided (a) the total length in the longitudinal direction, and (b) the sectional view which provided in the intermediate part in the longitudinal direction of the heat equalizing member of a heater member. It is a top view of the heater member which concerns on the modified embodiment of this invention. It is a top view of the heater member which changed the structure of the switch of FIG. 6A. It is sectional drawing of the heater member which shows four examples (a)-(d) which changed the position of a resistance pattern and the length of a heat equalizing member. It is a top view of the conventional heater member. It is an electric circuit diagram of the heater member of FIG. 8A. It is a figure which shows the structure of another fixing device. It is a figure which shows the structure of the other fixing device.

Hereinafter, the heater member, the fixing device, and the image forming apparatus (laser printer) according to the embodiment of the present invention will be described with reference to the drawings. The laser printer is an example of an image forming apparatus, and it goes without saying that the image forming apparatus is not limited to the laser printer. That is, the image forming apparatus can be configured as any one of a copying machine, a facsimile, a printer, a printing machine, and an inkjet recording device, or a multifunction device in which at least two or more of these are combined.

The same or corresponding parts in each figure are designated by the same reference numerals, and the duplicated description thereof will be appropriately simplified or omitted. Further, the dimensions, materials, shapes, relative arrangements thereof, etc. in the description of each component are examples, and the scope of the present invention is not intended to be limited thereto unless otherwise specified.

In the following embodiments, the "recording medium" which is a sheet material will be described as "paper", but the "recording medium" is not limited to paper (paper). The "recording medium" includes not only paper (paper) but also OHP sheets, cloths, metal sheets, plastic films, prepreg sheets in which carbon fibers are preliminarily impregnated with resin, and the like.

A medium to which a developer or ink can be attached, a recording paper, and a recording sheet are all included in the "recording medium". In addition to plain paper, "paper" also includes thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, and the like.

Further, the "image formation" used in the following description is not only to give an image having a meaning such as characters or figures to the medium, but also to give an image having no meaning such as a pattern to the medium. Also means.

(Laser printer configuration)
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. In addition to the printer, the image forming apparatus may be a copying machine, a facsimile, or a combination machine thereof.

The image forming apparatus 100 shown in FIG. 1 includes four image forming units 1Y, 1M, 1C, and 1Bk, which are image forming units. Each image forming unit 1Y, 1M, 1C, 1Bk is configured to be detachably attached to the image forming apparatus main body 103, and develops different colors of yellow, magenta, cyan, and black corresponding to the color separation component of the color image. It has the same structure except that it is housed.

Specifically, each image processing unit 1Y, 1M, 1C, 1Bk is formed on the drum-shaped photoconductor 2 as an image carrier, the charging device 3 for charging the surface of the photoconductor 2, and the surface of the photoconductor 2. It includes a developing device 4 that supplies toner as a developing agent to form a toner image, and a cleaning device 5 that cleans the surface of the photoconductor 2.

Further, the image forming apparatus 100 is formed on each photoconductor 2, an exposure apparatus 6 that exposes the surface of each photoconductor 2 to form an electrostatic latent image, a paper feeding device 7 that supplies paper P as a recording medium, and each photoconductor 2. A transfer device 8 for transferring the transferred toner image to the paper P, a fixing device 300 for fixing the toner image transferred to the paper P, and a paper ejection device 10 for discharging the paper P to the outside of the device are provided.

The transfer device 8 includes an endless intermediate transfer belt 11 as an intermediate transfer body stretched by a plurality of rollers, and four primary transfer members for transferring a toner image on each photoconductor 2 to the intermediate transfer belt 11. It has a primary transfer roller 12 and a secondary transfer roller 13 as a secondary transfer member that transfers the toner image transferred on the intermediate transfer belt 11 to the paper P. Each of the plurality of primary transfer rollers 12 is in contact with the photoconductor 2 via the intermediate transfer belt 11.

As a result, the intermediate transfer belt 11 and each photoconductor 2 are in contact with each other, and a primary transfer nip is formed between them. On the other hand, the secondary transfer roller 13 is in contact with one of the rollers that stretches the intermediate transfer belt 11 via the intermediate transfer belt 11. As a result, a secondary transfer nip is formed between the secondary transfer roller 13 and the intermediate transfer belt 11.

Further, in the image forming apparatus 100, a paper conveying path 14 for conveying the paper P sent out from the paper feeding device 7 is formed. A pair of timing rollers 15 are provided on the way from the paper feeding device 7 to the secondary transfer nip (secondary transfer roller 13) in the paper transport path 14.

Next, the printing operation of the image forming apparatus will be described with reference to FIG.

When instructed to start the printing operation, in each image forming unit 1Y, 1M, 1C, 1Bk, the photoconductor 2 is rotationally driven clockwise in FIG. 1, and the surface of the photoconductor 2 is uniformly raised by the charging device 3. It is charged to the electric potential. Next, the exposure device 6 exposes the surface of each photoconductor 2 based on the image information of the document read by the document reader or the print information instructed to print from the terminal, so that the potential of the exposed portion is increased. It is lowered to form an electrostatic latent image. Then, toner is supplied from the developing device 4 to the electrostatic latent image, and a toner image is formed on each photoconductor 2.

When the toner image formed on each photoconductor 2 reaches the primary transfer nip (position of the primary transfer roller 12) as the photoconductor 2 rotates, the intermediate transfer belt is rotationally driven counterclockwise in FIG. It is transferred to 11 so as to sequentially overlap. Then, the toner image transferred onto the intermediate transfer belt 11 is conveyed to the secondary transfer nip (position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates, and is conveyed at the secondary transfer nip. Transferred to paper P.

This paper P is supplied from the paper feeding device 7. The paper P supplied from the paper feed device 7 is temporarily stopped by the timing roller 15, and then transferred to the secondary transfer nip at the timing when the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip. Thus, a full-color toner image is supported on the paper P. Further, after the toner image is transferred, the toner remaining on each photoconductor 2 is removed by each cleaning device 5.

The paper P on which the toner image is transferred is conveyed to the fixing device 300, and the toner image is fixed on the paper P by the fixing device 300. After that, the paper P is ejected to the outside of the paper ejection device 10, and a series of printing operations is completed.

(Principle of laser printer)
FIG. 2A is a principle diagram of a laser printer as an embodiment of an image forming apparatus 100 provided with the fixing apparatus 300 of the present invention. The image forming apparatus 100 has an image carrier 2 (for example, a photoconductor drum) and a drum cleaning apparatus 5. Further, a charging device 3 as a charging means for uniformly charging the surface of the image carrier, a developing device 4 as a developing means for performing visible image processing of an electrostatic latent image formed on the image carrier, and an image carrier. It has a transfer means T disposed below the body 2, a static eliminator, and the like.

The exposure apparatus 6 is arranged above the image carrier 2. The exposure apparatus 6 performs write scanning according to the image information, that is, reflects the laser beam Lb from the laser diode by the mirror 6a based on the image data and irradiates the image carrier 2.

The paper feeding device 50 having a tray for loading the paper P is installed below the image forming device 100. The paper feeding device 50 can accommodate a large number of sheets P as a recording medium in a bundle, and is unitized together with a paper feed roller 60 as a means for transporting the paper P.

A resist roller pair 250 as a separation and transporting means is arranged on the downstream side of the paper feed roller 60. The paper P fed from the paper feeding device 50 is temporarily stopped by the resist roller pair 250. By this temporary stop, a slack is formed on the tip side of the paper P, and the skew of the paper P is corrected.

The paper P, which is abutted against the resist roller pair 250 and has a slack formed at the tip end portion, is sent out to the transfer nip N of the transfer means T at the timing when the toner image on the image carrier 2 is suitably transferred. Then, on the paper P that has been sent out, the toner image on the image carrier 2 is electrostatically transferred to a desired transfer position by the bias applied at the transfer nip N.

A fixing device 300 is arranged on the downstream side of the transfer nip N. The fixing device 300 includes a fixing belt 310 as a fixing member heated by a resistance pattern 332 described later, and a pressure roller 320 as a pressure member that rotates while abutting on the fixing belt 310 at a predetermined pressure. There is.

(Laser printer operation)
Next, the basic operation of the laser printer according to this embodiment will be described. The paper feed roller 60 rotates in response to the paper feed signal from the control unit of the image forming apparatus 100. The rotation of the paper feed roller 60 separates the top-level paper of the bundled paper P loaded on the paper feed device 50 and feeds it to the paper feed path.

When the tip of the fed paper P reaches the nip of the resist roller pair 250, it forms a slack and stands by in that state. Then, the optimum timing (synchronization) for transferring the toner image on the image carrier 2 to the paper P is set, and the tip skew of the paper P is corrected.

The charging device 3 uniformly charges the surface of the image carrier 2 to a high potential. Then, the exposure apparatus 6 reflects the laser beam Lb based on the image data by the mirror 6a and irradiates the surface of the image carrier 2.

On the surface of the image carrier 2 irradiated with the laser beam Lb, the potential of the irradiated portion is lowered to form an electrostatic latent image. The developer 4 has a developer carrier 4a that supports a developer containing toner, and an electrostatic latent image is formed on the unused black toner supplied from the toner bottle via the developer carrier 4a. The image carrier 2 is transferred to the surface portion of the image carrier 2.

The image carrier 2 to which the toner is transferred forms (develops) a toner image on the surface thereof. Then, the toner image formed on the image carrier 2 is transferred to the paper P by the transfer means T.

The drum cleaning device 5 removes residual toner adhering to the surface of the image carrier 2 after the transfer process with the cleaning blade 5a. The removed residual toner is collected in the waste toner accommodating portion.

The paper P on which the toner image is transferred is conveyed to the fixing device 300. The paper P conveyed to the fixing device 300 is sandwiched between the fixing belt 310 and the pressure roller 320, and the unfixed toner image is fixed to the paper P by heating and pressurizing. The paper P on which the toner image is fixed is sent out from the fixing device 300.

(Fixing device)
Subsequently, the configuration of the fixing device 300 will be described. As shown in FIG. 2B, the fixing device 300 according to the present embodiment has a fixing belt 310 made of an endless belt member as a fixing member and an opposing member that contacts the outer peripheral surface of the fixing belt 310 to form a nip N. The pressure roller 320 and the heater member 330 for heating the fixing belt 310 are provided. The heater member 330 is held by the heater holder 344, and the heater holder 344 is reinforced in the longitudinal direction by the stay 350 as a reinforcing member.

The fixing belt 310 is made of a flexible sleeve-shaped rotating member, and has, for example, a polyimide (PI) tubular substrate having an outer diameter of 25 mm and a thickness of 40 to 120 μm. On the outermost surface layer of the fixing belt 310, a mold release layer having a thickness of 5 to 50 μm is formed of a fluororesin such as PFA or PTFE in order to enhance durability and ensure mold release.

An elastic layer made of rubber or the like having a thickness of 50 to 500 μm may be provided between the substrate and the release layer. Further, the substrate of the fixing belt 310 is not limited to polyimide, and may be a heat-resistant resin such as PEEK or a metal substrate such as nickel (Ni) or SUS. Polyimide, PTFE, or the like may be coated on the inner peripheral surface of the fixing belt 310 as a sliding layer.

The pressure roller 320 has, for example, an outer diameter of 25 mm, and has a solid iron core metal 321, an elastic layer 322 formed on the surface of the core metal 321 and a mold release layer formed on the outside of the elastic layer 322. It is composed of 323 and. The elastic layer 322 is made of silicone rubber and has a thickness of, for example, 3.5 mm. It is desirable that the surface of the elastic layer 322 forms a mold release layer 323 made of a fluororesin layer having a thickness of, for example, about 40 μm, in order to improve the mold release property.

The heater member 330 is provided longitudinally across the width direction of the fixing belt 310, and is arranged so as to come into contact with the inner peripheral surface of the fixing belt 310. The heater member 330 may be in non-contact with the fixing belt 310 or indirectly with a low friction sheet or the like, but it is better to bring the heater member 330 into direct contact with the fixing belt 310. The heat transfer efficiency to the fixing belt 310 is improved.

Further, the heater member 330 can be brought into contact with the outer peripheral surface of the fixing belt 310, but if the outer peripheral surface of the fixing belt 310 is damaged by the contact with the heater member 330, the fixing quality may deteriorate. Therefore, the heater member 330 Should be in contact with the inner peripheral surface of the fixing belt 310.

The heater member 330 is composed of a base material 331, a resistance pattern 332 laminated on the nip N side of the base material 331, and an insulating layer 333.

The base material 331 can be made of, for example, a ceramic such as alumina or aluminum nitride. Since ceramic has a linear expansion coefficient close to that of glass, when glass is used for the insulating layer 333, there is an advantage that shearing force is not easily applied to the resistor 332 due to the displacement between the base material 331 and the insulating layer 333 during thermal expansion.

Further, since the thermal conductivity of ceramic is higher than that of metal such as stainless steel, it is advantageous to conduct heat to the fixing belt 310 via the base material 331. As the material of the base material 331, in addition to ceramic, glass, mica and the like are also preferable because of their excellent heat resistance and insulating properties. In this embodiment, an alumina base material having a short width of 8 mm, a longitudinal width of 270 mm, and a thickness of 1.0 mm is used.

The heater holder 344 and the stay 350 are arranged on the inner peripheral side of the fixing belt 310. The stay 350 is made of a metal channel material, and both end portions thereof are supported by both side wall portions of the fixing device 300.

The stay 350 supports the surface of the heater holder 344 opposite to the heater member 330 side. As a result, the heater member 330 and the heater holder 344 are supported without being significantly bent by the pressure applied from the pressurizing roller 320. A nip N is stably formed between the fixing belt 310 and the pressure roller 320.

Since the heater holder 344 tends to become hot due to the heat of the heater member 330, it is desirable that the heater holder 344 is made of a heat-resistant material. For example, when the heater holder 344 is made of a heat-resistant resin having low thermal conductivity such as LCP or PEEK, heat transfer from the heater member 330 to the heater holder 344 is suppressed, and the fixing belt 310 can be heated efficiently. Is.

The pressure roller 320 and the fixing belt 310 are pressed against each other by a spring as an urging member. As a result, a nip N is formed between the fixing belt 310 and the pressure roller 320. Further, the pressure roller 320 functions as a drive roller that is rotationally driven by transmitting a driving force from the driving means provided in the image forming apparatus main body 103.

On the other hand, the fixing belt 310 is configured to be driven to rotate with the rotation of the pressure roller 320. During rotation, the fixing belt 310 slides with respect to the heater member 330. In order to improve the slidability of the fixing belt 310, a lubricant such as oil or grease may be interposed between the heater member 330 and the fixing belt 310.

When the printing operation is started, the pressure roller 320 is rotationally driven, and the fixing belt 310 starts driven rotation. Further, the fixing belt 310 is heated by supplying electric power to the heater member 330. Then, in a state where the temperature of the fixing belt 310 reaches a predetermined target temperature (fixing temperature), as shown in FIG. 2B, the paper P on which the unfixed toner image is carried is the fixing belt 310 and the pressure roller 320. By being conveyed to the space (nip N), the unfixed toner image is heated and pressurized and fixed on the paper P.

(Basic embodiment of heater member)
FIG. 3A shows a basic embodiment of the heater member 330. As shown in FIG. 3A, the main body portion of the heater member 330 is composed of the base material 331. In the longitudinal direction of the base material 331, the main body of the resistance pattern is formed, and two rows of resistors 332 that generate heat by energization are formed linearly and parallel to each other.

The two rows of resistors 332 are separated from each other in the lateral direction perpendicular to the longitudinal direction of the base material 331, and are connected in parallel with the electrodes 337a and 337b as described later. The portion shown by the rectangular broken line in FIG. 3A is the heat equalizing member 339.

The heat equalizing member 339 is arranged across two rows of the resistors 332 in the lateral direction of the base material 331 to reduce the temperature difference between the rows of the resistors 332. Here, "straddling" means that the resistance thermometer member 339 completely or partially overlaps both of the two rows of resistance 332s in a plan view of the two rows of resistance 332s when viewed from the thickness direction thereof. To say.

The heat soaking member 339 is arranged on a surface (upper surface in FIG. 5) opposite to the nip forming surface (lower surface in FIG. 5) of the heater member 330, as shown in FIGS. 5 (a) and 5 (b) described later. .. The heat equalizing member 339 can be made of an aluminum plate (236 W / m · K), which is a high heat conductive material, a copper plate (403 W / m · K), a graphite sheet (700 W / m · K), or the like.

The dimensions and resistance values of the two rows of resistors 332 are as follows in this embodiment.
-Width of resistor 332 in the lateral direction: 2.0 mm
-Interval distance in the lateral direction of the resistor 332: 0.7 mm
-Width in the lateral direction of the resistance pattern: 4.7 mm (= 2.0 x 2 + 0.7)
-Resistance value of resistor 332: 16Ω
Longitudinal width of resistor 332: 216-220 mm

The two rows of resistors 332 are formed by, for example, applying a resistance material paste containing silver palladium (AgPd), glass powder, or the like to the base material 331 by screen printing or the like, and then firing the base material 331. can do. In addition to these, a silver alloy (AgPt) or ruthenium oxide (RuO ₂ ) resistance material may be used as the resistance material.

The two rows of resistors 332 do not necessarily have to be linear as in FIG. 3A. Instead of a linear shape, a shape in which the waveform is continuous may be used. As a result, the length of the resistor 332 can be increased, and the specific resistance of the resistance material paste can be lowered.

Two electrodes 337a and 337b to which an AC power source is connected are arranged at one end in the longitudinal direction of the base material 331. One electrode 337a and one end of two rows of resistors 332 are connected by a conductor 338a having a resistance value smaller than that of the resistor 332. Further, the other electrode 337b and the other end of the two rows of resistors 332 are similarly connected by a conductor 338b having a resistance value smaller than that of the resistor 332.

A thermostat TH as a current cutoff member for cutting off power supply to the resistor 332 or a thermistor TM as a temperature detection member is arranged in the center of the two rows of resistors 332 in the longitudinal direction. The thermostat TH (or thermistor TM) is disposed across the two rows of resistors 332 in the lateral direction of the base material 331 to the resistor 332, and is disposed so as to overlap the heat soaking member 339. ..

The term "straddling" means that the thermostat TH completely or partially overlaps both of the two rows of resistors 332 in a plan view of the two rows of resistors 332 in the thickness direction thereof. Further, "arranged so as to overlap the heat equalizing member 339" means that the thermostat TH (or thermistor TM) completely or partially overlaps the heat equalizing member 339 in a plan view seen from the thickness direction of the heat equalizing member 339. It means that you are. When the temperature of any of the two rows of resistors 332 reaches a high temperature threshold (for example, more than 180 ° C and less than 200 ° C), the thermostat TH is configured to cut off the power supply to the resistors 332 for safety.

In addition to the thermostat TH, the thermistor TM as a temperature detecting member is also arranged in the two rows of resistors 332. One thermistor TM is disposed at least in the center of the resistor 332 in the longitudinal direction, and preferably one more is disposed in one end in the longitudinal direction (right end or left end).

When the fixing device 300 is operated, the temperature of the fixing belt 310 is maintained and controlled to a desired fixing temperature (for example, 170 ° C.) by these thermistors TM. Here, "detecting the temperature of the resistor 332" includes not only directly measuring the temperature of the resistor 332 with a sensor or the like, but also estimating the temperature based on some parameter.

The thermostat TH and thermistor TM are urged toward the base material 331 by, for example, a spring as an elastic member. The urging by this spring reduces the contact gap between the thermostat TH and the thermistor TM with respect to the base material 331. Therefore, the exact temperature of the resistor 332 is transmitted to the thermostat TH, and the thermistor TM can detect the exact temperature of the resistor 332.

The thermostat TH and thermistor TM at the central portion in the longitudinal direction of the resistor 332 of FIG. 3A are arranged within the range of the minimum paper width. Further, the thermistor TM at the right end portion or the left end portion of the resistor 332 is arranged in the paper passing end region of the maximum paper width. Then, regardless of the paper size, the toner image supported on the paper is fixed on the paper at a desired fixing temperature (for example, 170 ° C.).

By arranging the thermostat TH and thermistor TM in a paper sheet of any paper size, it is possible to prevent the influence of the temperature rise at the edge of the non-paper sheet portion. Therefore, when abnormal heat is generated due to a failure, the thermostat TH enables early power interruption. If the thermostat TH is arranged in the non-passing portion, it is necessary to set the operating temperature of the thermostat TH high in order to prevent false detection, which is disadvantageous in terms of safety.

(Action of heat soaking member)
In FIG. 3A described above, the thermostat TH (or thermistor TM) is arranged so as to be entirely overlapped in the lateral direction across both of the two rows of resistors 332, but the thermostat TH (or thermistor TM) having a slightly smaller diameter is arranged as shown in FIG. 3B. Alternatively, the thermistor TM) may be arranged so as to overlap only one of the two rows of resistors 332. The "arranged so as to overlap" means that the thermostat TH (or thermistor TM) completely or partially overlaps the resistor 332 in a plan view seen from the thickness direction of the resistor 332. When an overheating occurs in the lower resistor 332 where the thermostat TH (or thermistor TM) does not overlap, the temperature is transferred to the thermostat TH (or thermistor TM) by the heat soaking member 339.

Therefore, when the temperature rises excessively, the thermostat TH can safely and surely cut off the power supply to the resistor 332. Further, the temperature of the resistor 332 detected by the thermistor TM is averaged by the heat soaking member 339, the detection error due to the variation in the mounting position of the thermistor TM is reduced, and the temperature of the resistor 332 is set to a desired temperature (for example, 170 ° C.). ) Can be maintained and controlled.

Assuming that there is no heat equalizing member 339, the detection temperature of the thermostat TH (or thermistor TM), which causes an excessive temperature rise in the lower resistor 332 of FIG. 3B, does not rise, or the temperature rise rate becomes slow. If the temperature is controlled in such a state, the detection temperature of the thermistor TM remains low even though the actual heater temperature is high, so that the power is continuously turned on. In that case, the actual heater temperature becomes higher than expected, which may cause damage to members or ignition.

FIG. 3C is an example in which a thermostat TH having a slightly smaller diameter is arranged exactly in the middle of two rows of resistors 332. The thermostat TH (or thermistor TM) does not completely overlap any of the two rows of resistors 332, but partially overlaps both resistors 332.

Also in the heater member 330 of FIG. 3C, the temperature of the two rows of resistors 332 is transferred to the thermostat TH (or thermistor TM) via the heat soaking member 339. Therefore, even if an overheating occurs in any of the resistors 332, the thermistor TM safely and surely cuts off the power supply to the resistor 332, and the thermistor TM keeps the temperature of the resistor 332 at a desired temperature (for example, 170). Can be maintained and controlled at ℃).

(Application embodiment of heater member)
FIG. 4A shows an application embodiment of the heater member 330, in which three resistance patterns 332a, 332b, and 332c are formed in the longitudinal direction of the base material 331. That is, the first resistance pattern 332a formed in the central portion in the longitudinal direction and the second resistance patterns 332b and 332c formed in both ends in the longitudinal direction.

For the three resistance patterns 332a, 332b, and 332c, for example, a resistance material paste having the same resistivity, which is a mixture of silver palladium (AgPd) or glass powder, is applied to the base material 331 by screen printing or the like, and then the base material is applied. It can be formed by firing 331. In addition to these, a silver alloy (AgPt) or ruthenium oxide (RuO ₂ ) resistance material may be used as the resistance material. When a material having a positive temperature coefficient of resistance is used as the resistance material, a material having a temperature coefficient of resistance of 300 ppm can be used, for example.

By selectively energizing and heating these three resistance patterns 332a, 332b, and 332c, each paper size (A3 to A6) is efficiently heated. That is, when passing and heating large size paper such as A3 paper and B4 paper, all resistance patterns 332a, 332b, and 332c are energized and heated. On the other hand, when passing and heating small-sized paper such as A4, B5, A5, B6, and A6, only the central resistance pattern 332a is energized and heated.

The first resistance pattern 332a at the center in the longitudinal direction has four rows of resistors 332a1 to 332a4 as the first resistors linearly extending in the longitudinal direction of the base material 331. A rectangular plate-shaped heat equalizing member 339 is arranged so as to completely include these four rows of resistors 332a1 to 332a4 in a plan view. As shown in FIG. 5B, the heat equalizing member 339 is arranged on the surface of the heater member 330 opposite to the nip forming surface.

The four rows of resistors 332a1 to 332a4 have the same length, width, and thickness, and are arranged at equal intervals and in parallel with each other. By using four rows, the amount of heat generated per row can be suppressed (to prevent the resistance value from becoming too small).

The central first resistance pattern 332a has a larger heat generation region than the second resistance patterns 332b and 332c at both ends. Therefore, the first resistance pattern 332a in the center requires a large amount of electric power, and conversely, the resistance value needs to be small.

The resistance value can be reduced by making the four rows of resistors 332a1 to 332a4 linear (shortest length). Thereby, as described later, the first resistance pattern 332a in the center and the second resistance patterns 332b and 332c at both ends can be formed by the material paste having the same resistivity.

That is, assuming that the required calorific value of the entire first resistance pattern 332a is 900 W, the calorific value per row is 225 W in four equal parts. Assuming that the length of the first resistance pattern 332a in the longitudinal direction is 216 mm, the heat generation density [W / mm] is 1.04 [W / mm].

On the other hand, the second resistance patterns 332b and 332c at both ends in the longitudinal direction, which will be described later, are continuous in a zigzag manner in the lateral direction of the base material 331 to increase the total length (the resistance value is earned). Here, when the length of the second resistance pattern 332b and 332c in the longitudinal direction is 43 mm, the resistance pattern 332b and 332c have the same heat generation density [W / mm] in the longitudinal direction as the first resistance pattern 332a in the center. In order to obtain the heat, the second resistance pattern 332b and 332c require a calorific value of 179 W each by the following calculation.
Central first resistance pattern 332a: 900W / 216mm = 4.17W / mm
Second resistance pattern 332b at both ends, c: 179W / 43mm = 4.16W / mm

When the length of the second resistance pattern 332b and 332c in the longitudinal direction is 43 mm and the zigzag folds are formed three times (four steps), the total length of the resistance patterns 332b and 332c is 172 mm. The heat generation density [W / mm] is 1.04 [W / mm], and it can be seen that the three resistance patterns 332a to 332c can be formed by the resistance material having the same resistivity. As a result, the three resistance patterns 332a to 332c can be screen-printed at the same time, which contributes to cost reduction.

Both ends of the four rows of resistors 332a1 to 332a4 in the longitudinal direction are connected in parallel to the electrodes 337c and 337f via conductors 338c, 338f2 and 338f3. The right electrode 337f is connected to one pole of the 100V AC power supply PW, and the other electrodes 337c, 337d, 337e are connected to the other pole of the 100V AC power supply PW via switches SW1 and SW2.

Therefore, by operating the switches SW1 and SW2, the central resistance pattern 332a and the resistance patterns 332b and 332c at both ends can be independently energized / cut off. As a result, the fixing device 300 can be adapted to various paper sizes, and the energy saving of the fixing device 300 can be improved by turning off the electric power of the unnecessary portion. Further, by intermittently energizing and heating only the second resistance patterns 332b and 332c at both ends by operating the switch SW2, it is possible to suppress the tendency of temperature dripping at both ends of the paper passing portion of the fixing belt 310.

The four rows of resistors 332a1 to 332a4 described above do not necessarily have to be linear as shown in FIG. 4A. Instead of a linear shape, a shape in which the waveform is continuous may be used. As a result, the lengths of the resistors 332a1 to 332a4 can be increased, and the specific resistance of the resistance material paste can be reduced.

The thermostat TH1 as a current cutoff member is arranged so as to straddle the central two rows of resistors 332a2 and 332a3 in the lateral direction of the four rows of resistors 332a1 to 332a4. Then, even when the temperature of any of the four rows of resistors 332 reaches the high temperature threshold value (for example, more than 180 ° C. and less than 200 ° C.), heat is transferred to the thermostat TH1 via the heat equalizing member 339 to supply power to the resistor 332. It is configured to shut off for safety. That is, no matter which of the plurality of resistors 332a1 to 332a4 formed in the lateral direction is disconnected, the excessive temperature rise due to the abnormality is transferred to the thermostat TH1 via the heat equalizing member 339 to supply power to the resistor 332. Is blocked and safety is ensured.

As shown in FIGS. 5A and 5B, the heat equalizing member 339 is arranged on a surface (upper surface in FIG. 5) opposite to the nip forming surface (lower surface in FIG. 5) of the heater member 330. Thermistors TM1 and TM2 as temperature detecting members are attached to the outer surface of the heat equalizing member 339 in FIG. 5A, and the thermistor TM1 is attached in FIG. 5B. The rectangular contour of the heat equalizing member 339 is formed so as to overlap the heating region of the nip N described above.

As shown in FIG. 4A, the thermistor TM1 is arranged in the vicinity of the thermostat TH1. The thermistor TM1 is arranged so as to straddle the resistors 332a2 and 332a3 in the central two rows in the lateral direction in consideration of the variation in the mounting position. The thermostat TH1 and thermistor TM1 are arranged in the longitudinal direction of the base material 331 almost in the center, which is not easily affected by the temperature rise of the non-passing portion during paper passing, and are arranged within the range of the minimum paper width (for example, A6 paper width). It is set up.

The second resistance patterns 332b and 332c at both ends in the longitudinal direction are composed of a second resistor that is continuous in a zigzag manner in the lateral direction of the base material 331. The width in the lateral direction of the second resistance patterns 332b and 332c at both ends is the same as the width in the lateral direction of the first resistance pattern 332a in the center. Further, the longitudinal width of the second resistance pattern 332b and 332c is a fraction of the longitudinal width of the central first resistance pattern 332a.

The zigzag fold of the second resistance pattern 332b and 332c is composed of four steps in the lateral direction of the base material 331. The line width and thickness of the resistance patterns 332b and 332c are set so that the resistance value (heat generation distribution) becomes uniform in the longitudinal direction of the base material 331 including the resistance pattern 332a.

By making the lengths of 332b, 332c332b, and 332c by winding in a zigzag manner, the specific resistance of the resistivity material paste can be lowered, and the unevenness of the temperature distribution in the lateral direction can be suppressed. If the resistance patterns 332b and 332c are not folded in a zigzag manner but are made into a single pattern in the lateral direction, a local high temperature portion is formed, which is not preferable.

On the other hand (left side), the thermistor TM2 is arranged so as to straddle the second and third stages of the resistance pattern 332b. The position of the thermistor TM2 in the longitudinal direction is substantially the center of the resistance pattern 332b in the longitudinal direction. By arranging the thermistor TM2 at the center position of the resistance pattern 332b in this way, the accurate temperature of the resistance pattern 332b can be detected.

The thermostat TH2 is arranged so as to straddle the second and third stages of the resistance pattern 332c on the other side (right side). The longitudinal position of the thermostat TH2 does not necessarily have to be the longitudinal center of the resistance pattern 332c.

The temperature of the fixing belt 310 is controlled to a desired temperature by controlling the electric power supplied to the heater member 330 by the heating control means according to the detection temperature detected by the thermistors TM1 and TM2 described above. The heating control means means a microcomputer including a CPU, ROM, RAM, I / O interface and the like. However, at the time of paper passing or the like, the temperature of the fixing belt 310 is controlled to a desired temperature by appropriately applying additional power in consideration of the heat removal due to the paper passing, in addition to the detected temperature.

(Function of heat equalizing member at the time of disconnection)
Next, the influence when the disconnection occurs in the first resistance pattern 332a at the center of the heater member 330 will be described with reference to FIGS. 4B and 4C. In FIGS. 4B and 4C, the thermostat TH1 and the thermistor TM1 are arranged so as to straddle the upper two rows of resistors 332a1 and 332a2. In FIG. 4A, the thermostat TH1 and the thermistor TM1 are arranged so as to straddle the resistance bodies 332a2 and 332a3 in the central two rows in the lateral direction. It may be arranged across the bodies 332a1 and 332a2.

Here, it is assumed that the resistor 332a1 in the first row shown in white in FIG. 4B is disconnected. When the thermostat TH1 or thermistor TM1 is arranged on the disconnected resistor 332a1, the thermistor TM1 detects an excessive temperature rise before the disconnection, and when the temperature of the resistor 332a1 exceeds the high temperature threshold, the thermostat TH1 heats the heater. The power supply to the member 330 is cut off for safety.

However, when the resistor 332a4 in the fourth row shown in white in FIG. 4C is disconnected, if the heat soaking member 339 is not present, the thermistor TM1 cannot detect the excessive temperature rise before the disconnection. Further, even if the temperature of the resistor 332a4 exceeds the high temperature threshold value, the high temperature is not transmitted to the thermostat TH1. Therefore, it is not possible to cut off the power supply to the heater member 330 at the time of abnormal heat generation due to a failure.

In the present embodiment, since the heat equalizing member 339 is arranged so as to overlap all of the four-row resistors 332a connected in parallel, the thermostat TH1 and the thermistor TM1 are arranged at any position of the four-row resistors 332a. Even if the resistance is increased, and even if an overheating occurs in any of the resistors 332a1 to 332a4, the overheating can be reliably detected and the power supply to the heater member 330 can be safely cut off.

On the other hand, since the second resistance patterns 332b and 332c at both ends are composed of one continuous resistance wire by winding in a zigzag manner, if a disconnection occurs at any of the resistance patterns 332b and 332c, the disconnection causes the disconnection. The energization of the resistance patterns 332b and 332c is cut off. Therefore, the thermostat TH2 and thermistor TM2 are arranged so as to overlap at least a part of the second resistance patterns 332b and 332c without extending the heat equalizing member 339 in the region including the second resistance patterns 332b and 332c at both ends. As long as it is, there is no problem at all.

(Modification example of heater member)
6A and 6B show a modification of the heater member 330 of FIG. 4A. 6A and 6B differ from the heater member 330 of FIG. 4A in the following points.
-The size (diameter) of the thermostats TH1 and TH2 has been increased.
-The number of zigzag folds of the second left and right resistance patterns 332b and 332c has been increased from 4 to 5.

By increasing the size (diameter) of the thermostats TH1 and TH2, the central thermostat TH1 overlaps all the rows of the four rows of resistors 332a1 to 332a4, and the number of stages of the end thermostat TH2 also overlapping the resistors 332c increases. Therefore, it is possible to improve the safety of the resistor 332a in the event of a disconnection failure and improve the stability of the temperature control of the resistor 332c. Further, by increasing the number of zigzag steps from 4 steps to 5 steps, the heat generation region in the lateral direction can be increased, and thereby the tendency of temperature dripping at the end of the paper passing width can be suppressed.

The heater member 330 of FIGS. 6B and 4A further has a different switch configuration. That is, in FIG. 6B, the parallel switches SW1 and SW2 of FIG. 4A are connected in series, and the switch SW1 and the electrode 337c are branched into the switch SW2. By changing the position of the switch SW1, the ON-OFF control of the central resistance pattern 332a and the ON-OFF control of the full-width resistance patterns 332a to 332c can be switched.

(Example of arrangement of resistance pattern and heat equalizing member)
7 (a) to 7 (d) show an example of arrangement of the resistance patterns 332a to 332c and the heat equalizing member 339 with respect to the thermostats TH1 and TH2 and the thermistors TM1 and TM2 as seen from the longitudinal cross section of the heater member 330. be. 7 (a) and 7 (b) show resistance patterns 332a to 332c formed on the fixing belt 310 side of the base material 331. The heat of the resistance patterns 332a to 332c is transferred to the thermostat TH1 and thermistor TM1 disposed on the opposite side (anti-fixing belt 310 side) of the base material 331.

Insulating glass 334 is laminated in two layers between the thermostat TH and the base material 331. Insulating glass 335 is also laminated above and below the resistor 332.

In FIG. 7A, the thermostat TH1 and thermistor TM1 arranged so as to overlap the central resistance pattern 332a are arranged on the heat equalizing member 339. The thermostat TH2 and thermistor TM2 at both ends are attached to the base material 331 via an insulating glass 334 so as to overlap the second resistance patterns 332b and 332c at both ends without passing through the heat equalizing member 339.

Since the second resistance patterns 332b and 332c at both ends are continuous resistance patterns with four steps in the short direction, the thermistor TM2 will prevent the overheating before the break even if the wire is broken in any step in the short direction. When the temperature of the resistor 332c exceeds the high temperature threshold, the thermostat TH2 cuts off the power supply to the heater member 330 for safety.

Therefore, the heat equalizing member 339 is not indispensable for the thermostat TH2 and thermistor TM2 at both ends. However, in order to further improve safety, the ends of the heat equalizing member 339 may be extended to the thermostats TH2 and thermistors TM2 at both ends as shown in FIG. 7B. By doing so, the effect of ensuring the complementary safety of the thermostats TH1 and TH2 or the thermistors TM1 and TM2 can be obtained.

In FIGS. 7 (c) and 7 (d), resistance patterns 332a to 332c are formed on the side of the base material 331 of the heater member 330 opposite to the fixing belt 310. The heat of the resistance patterns 332a to 332c is transferred to the thermostats TH1 and TH2 and the thermistors TM1 and TM2 via the insulating glass 334.

FIG. 7 (c) differs from FIG. 7 (b) only in the positions of the resistance patterns 332a to 332c. Since the resistance patterns 332a to 332c in FIG. 7 (c) are close to the thermostats TH1 and TH2 and the thermistors TM1 and TM2 in the thickness direction of the insulating glass 334, more accurate temperature is detected as compared with FIG. 7 (b). can do.

FIG. 7D shows a shortened length in the longitudinal direction of the heat equalizing member 339, similarly to FIG. 7A. The thermostat TH2 and thermistor TM2 at both ends detect the temperature of the second resistance pattern 332b and 332c without passing through the heat equalizing member 339.

(Suppressing variation in calorific value considering the magnitude of conductor resistance)
Next, the suppression of variation in the calorific value in consideration of the magnitude of the resistance value of the conductor connected to each resistance pattern will be described. FIG. 8A shows the arrangement state of the thermistors TM1, TM2, and the thermostats TH1 to TH5 with respect to the conventional heater member 330'.

Further, FIG. 8B is an electric circuit diagram of the configuration of FIG. 8A. In FIG. 8B, the resistance values R1 to R7 indicate the resistances of the respective resistance patterns 332a-1 to 332a-5, 332b, 332c, and the resistance values r1 to r14 are conductors 338c2 (r14), 338c1 (r10-r13), 338d. The resistance values of (r1), 338f1 (r2-r8), and 338e (r9) are shown.

Here, the resistance patterns 332a-1 to 332a-5, 332b, and 332c are referred to as heating elements 1 to 7 for convenience, and the electric resistance starts from the electrodes 337c to 337f and passes through the heating elements 1 to 7. The values are as follows.
Heating element 1: r1 + R1 + r2 + r3 + r4 + r5 + r6 + r7 + r8
Heating element 2: r14 + R2 + r3 + r4 + r5 + r6 + r7 + r8
Heating element 3: r14 + r13 + R3 + r4 + r5 + r6 + r7 + r8
Heating element 4: r14 + r13 + r12 + R4 + r5 + r6 + r7 + r8
Heating element 5: r14 + r13 + r12 + r11 + R5 + r6 + r7 + r8
Heating element 6: r14 + r13 + r12 + r11 + r10 + R6 + r7 + r8
Heating element 7: r8 + R7 + r9

Assuming that the resistivityes of the conductors 338c2, 338c1, 338d, 338e and the common conductor 338f are the same, the conductor of the resistance pattern 332b at the left end is longer than the conductor of the resistance pattern 332c at the right end, so that the resistance value is larger by (r2 + r3 + r4 + r5 + r6 + r7). turn into. Therefore, with the switch SW2 turned on, the resistance pattern 332b at the left end has a relatively smaller heat generation amount than the resistance pattern 332c at the right end, and the heat generation amount at both ends varies.

Similarly, the five resistance patterns 332a-1 to 332a-5 in the center have longer conductors than the resistance patterns 332c at the right end, so that the resistance value becomes large. Therefore, when the switches SW1 and SW2 are turned on, the heat generation amount of each resistance pattern 332a-1 to 332a-5 is smaller than that of the resistance pattern 332c at the right end, and the heat generation amount varies in the longitudinal direction.

Therefore, as shown in FIG. 8A, in the common conductor 338c and the conductor 338f, the conductors 338c1 and 338f1 connected to the resistance patterns 332a-1 to 332a-5, 332b and 332c have lower resistance than the other conductors. Specifically, as shown in FIG. 8A, the width of the conductors 338c1 and 338f1 is widened.

Instead of widening the conductors 338c1 and 338f1, or in combination with widening, the height (thickness) of the conductor may be increased (thickened), or a material having a low resistivity may be used for the conductors 338c1 and 338f1. can. This makes it possible to prevent heat generation variations in the resistance patterns 332a-1 to 332a-5, 332b, and 332c.

This idea is also applied to FIGS. 4A-4C and 6A-6B described above, and by forming the main body portion 338f1 of the common conductor 338f wider than the right end portion 338f2, the amount of heat generated in the longitudinal direction varies. Can be suppressed. Since the branch portion 338f3 is short, the influence on the heat generation variation is small even if the resistance value is ignored.

As described above, in the conventional heater member 330', among a total of seven resistance patterns 332a-1 to 332a-5, 332b, 332c, all resistance patterns other than the resistance pattern in which the thermistors TM1 and TM2 are arranged can be used. Basically, thermostats TH1 to TH5 are arranged respectively. That is, in the heater member 330', five resistance patterns 332a-1 to 332a-5 connected in parallel are arranged in the longitudinal direction in the region corresponding to the central resistance pattern 332a. Therefore, basically, the temperature detection member and the safety element must be arranged corresponding to the total number of resistance patterns of 7.

Therefore, the cost of the heater member 330'is increased by the large number of temperature detecting members and safety elements, and the temperature control based on the detected temperatures of the plurality of temperature detecting members is complicated. On the other hand, in the present embodiment of FIGS. 4A-4C and 6A-6B, since the heat generating portion of the heater member 330 is formed by the first and second resistance patterns 332a to 332c, the number of safety elements is increased. At least two are sufficient, and three safety elements can be reduced as compared with FIG. 8A.

That is, only one thermostat TH1 is provided in the region of the first resistance pattern 332a, for example, in the center, and one thermostat TH2 is provided at an arbitrary position in the region of either the left or right resistance pattern (resistance pattern 332c). It's fine. Therefore, the heater member 330 can be made space-saving, lightweight, and low-cost.

(Other types of fixing device)

The present invention can be applied to the fixing device 300 as shown in FIGS. 9 and 10 in addition to the fixing device 300 described above. In the fixing device 300 shown in FIG. 9, a pressing roller 370 is arranged on the side opposite to the pressure roller 320 side with respect to the fixing belt 310, and the fixing belt 310 is sandwiched between the pressing roller 370 and the heater member 330. It is configured to heat with.

On the other hand, on the pressure roller 320 side, the nip forming member 380 is arranged on the inner circumference of the fixing belt 310. The nip forming member 380 is supported by the stay 350, and the nip N is formed by sandwiching the fixing belt 310 between the nip forming member 380 and the pressure roller 320.

In the fixing device 300 shown in FIG. 10, a pressure belt 390 is provided in addition to the fixing belt 310, and the heating nip (first nip) N1 and the fixing nip (second nip) N2 are separately configured. That is, the nip forming member 380 and the stay 381 are arranged on the side opposite to the fixing belt 310 side with respect to the pressure roller 320, and the pressure belt 390 is rotated so as to include the nip forming member 380 and the stay 381. Arranged as possible.

Then, the paper P is passed through the fixing nip N2 between the pressure belt 390 and the pressure roller 320, heated and pressed to fix the image. Others have the same configuration as the fixing device 300 shown in FIG. 2B.

Although the various heater members 330 and the fixing device 300 have been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above embodiment, the heat equalizing member 339 is arranged so as to be overlapped with the four rows of resistors 332a1 to 332a4, but the heat equalizing member 339 is arranged so as to be overlapped with at least two rows of resistors, and the remaining A current cutoff member or a temperature detection member may be individually arranged on the resistor.

Alternatively, when the number of rows of resistors connected in parallel is large, it is also possible to dispose the heat equalizing member 339 for each of a predetermined number of rows of resistors. Even in this case, the number of current cutoff members and temperature detection members used can be reduced as compared with the conventional case.

Further, the current cutoff member is not limited to the thermostat, and a thermal fuse or the like can be used instead of the thermostat. Further, as the temperature detecting member, a semiconductor such as a thermistor whose resistance value changes according to a temperature change may be used, or a diode, a transistor or the like which uses a characteristic value change due to a temperature characteristic may be used.

Further, the heater member according to the present invention can be applied not only to a type fixing device that directly heats a thin-walled fixing belt, but also to a heat roller type fixing device in which a heater member is arranged on the inner circumference. Further, the heater member according to the present invention is not applied only to the fixing device. For example, the heater member according to the present invention can be applied to a drying device mounted on an inkjet image forming apparatus and a heater of an inkjet print head in order to dry the ink applied to the paper.

Further, the heater member according to the present invention can also be applied to a coating device (laminator) that thermocompression-bonds a film as a coating member to the surface of the sheet material while transporting a sheet material such as paper by a belt member. Further, the heater member according to the present invention is applicable not only to the belt heating device for heating the belt member but also to the heating device not provided with the belt member.

Further, the number of the first resistors 332a1 to 332a4 of the first resistance pattern 332a can be increased or decreased as necessary. Further, only one first resistance pattern 332a is arranged in the central portion in the longitudinal direction of the base material 331, and a plurality of patterns can be arranged in the longitudinal direction. For example, the first resistance pattern 332a may be arranged in a number of conventional resistance patterns or less. Can be done.

1Y, 1M, 1C, 1Bk: Image forming unit 2: Photoreceptor (image carrier)
3: Charging device 4: Developing device 4a: Developer carrier 5: Drum cleaning device 5a: Cleaning blade 6: Exposure device 6a: Mirror 7: Paper feeding device 8: Transfer device 10: Paper ejection device 11: Intermediate transfer belt 12 : Primary transfer roller 13: Secondary transfer roller 14: Paper transfer path 15: Timing roller 50: Paper feeding device 60: Paper feed roller 100: Image forming device 103: Image forming device main body 250: Resist roller pair 300: Fixing device 310: Fixing belt 320: Pressurized roller 321: Iron core metal 321: Core metal 322: Elastic layer 323: Demolding layer 330, 330': Heater member 331: Base material 332: Resistance pattern 332a: First resistance pattern 332a1 332a4: First resistor 332b, 332c: Second resistance pattern 336: Insulation material 344: Heater holder 350: Stay 360: Heater base material 370: Pressing roller 380: Nip forming member 381: Stay 390: Pressurized belt 332: Resistance pattern 332a: First resistance pattern 332a1 to 332a4: First resistor 332b, 332c: Second resistance pattern 333: Insulation layer 334, 335: Insulation glass 335: Insulation glass 336: Insulation material 337a to 337f : Electrodes 338a to 338f: Conductor 339: Heat soaking member Lb: Laser light N: Nip P: Paper PW: Power supply SW1, SW2: Switch TH1, TH2: Thermista
TH1 to TH5: Thermostat (current cutoff member) T: Transfer means

Japanese Patent No. 6336026 Japanese Unexamined Patent Publication No. 2016-6499 Japanese Patent No. 6228458

Claims (19)

It has a plurality of rows of resistors formed in the longitudinal direction of the substrate and generates heat by energization, and the plurality of rows of resistors are connected in parallel in a state of being separated from each other in the lateral direction orthogonal to the longitudinal direction of the substrate. Resistance pattern and
A heat equalizing member, which is arranged over at least two rows of the resistors in the lateral direction to reduce the temperature difference between the rows of the resistors.
A current cutoff member and / or at least two rows that are arranged so as to overlap the heat soaking member and cut off the power supply to the resistance pattern when the temperature of any one of the at least two rows or more of the resistors reaches the high temperature threshold. A temperature detection member that detects the temperature of any of the above resistors,
A heater member characterized by having. The heater member according to claim 1, wherein the resistor is continuously formed linearly in the longitudinal direction of the base material. The heater member according to claim 1 or 2, wherein the current cutoff member and / or the temperature detection member is urged toward the base material by an elastic member. The heater member according to any one of claims 1 to 3, wherein the heat soaking member is arranged over the entire row of the resistors. It has a heating member and a pressurizing member which have a longitudinal direction and are pressed against each other to form a nip, and the heating member is brought into contact with the heater member according to any one of claims 1 to 4 to be heated and heated to the nip. In a heating device that transfers heat from the heating member to the sheet material by passing it through the sheet material.
A heating device, wherein the current cutoff member is arranged within a range of the minimum width size of the sheet material. The present invention is characterized in that the current cutoff member and / or the temperature detection member is arranged on the side of the heater member according to any one of claims 1 to 4 opposite to the side in contact with the heating member. Item 5 heating device. A flexible sleeve-shaped rotating member and
The heater member according to any one of claims 1 to 4, which is in sliding contact with the inner circumference of the rotating member.
It has a pressurizing member that sandwiches the rotating member and presses against the heater member to form a nip between the rotating member and the heater member.
A heating device characterized in that heat of the heater member is transferred to the sheet material via the rotating member when the sheet material is sandwiched and conveyed by the nip. A fixing device comprising the heating device according to claim 7, wherein a toner image carried on the sheet material is passed through the nip and fixed by heating. An image forming apparatus including a paper feeding device, an image forming unit, a transfer device, and a fixing device according to claim 8. A heater member having three or more resistance patterns having a resistor that generates heat when energized in the longitudinal direction of the base material.
The first resistance pattern formed in the center of the substrate in the longitudinal direction has a plurality of rows of first resistors formed in the longitudinal direction of the substrate, and the first resistors in the plurality of rows are present. They are connected in parallel in a state of being separated from each other in the lateral direction orthogonal to the longitudinal direction of the substrate.
A heat equalizing member for reducing the temperature difference between the rows of the resistors is arranged so as to straddle at least two rows of the first resistors in the lateral direction.
A current cutoff member that cuts off the power supply to the resistance pattern when the temperature of any of the at least two rows or more of the resistors stacked on the heat soaking member reaches the high temperature threshold and / or the resistance of the at least two rows or more. A heater member characterized in that a temperature detecting member for detecting the temperature of any of the bodies is provided. The heater member according to claim 10, wherein the first resistor is continuously formed linearly in the longitudinal direction of the base material. The heater member according to claim 10 or 11, wherein the heat soaking member is arranged over the entire row of the first resistor. The second resistance pattern formed at both ends in the longitudinal direction of the base material has a second resistance body that is continuous in a zigzag manner in the lateral direction of the base material, and is characterized in that they are connected in parallel to each other. The heater member according to any one of claims 10 to 12. First and second temperature detecting members for detecting the temperature of each resistance pattern are arranged in the first and second resistance patterns, and the first and second resistance patterns are referred to as the first and second resistance patterns. The heater member according to claim 13, wherein the heater member is independently energized and shut off based on the detection result of the temperature detecting member of 2. The first and second temperature detecting members for detecting the temperature of each resistance pattern are arranged in the first and second resistance patterns, and the first and second resistance patterns are independently energized. The heater member according to claim 13, wherein the first control for shutting off and the second control for simultaneously energizing and shutting off can be switched. When the second temperature detecting member is arranged on one of the second resistance patterns and the temperature of the second resistance pattern reaches the high temperature threshold on the other second resistance pattern, both of them. The heater member according to claim 14 or 15, wherein a second current cutoff member that cuts off the power supply to the second resistance pattern is provided. A flexible sleeve-shaped rotating member and
The heater member according to any one of claims 10 to 16, which is in sliding contact with the inner circumference of the rotating member.
It has a pressurizing member that sandwiches the rotating member and presses against the heater member to form a nip between the rotating member and the heater member.
When a small-sized sheet material having a sheet width corresponding to the longitudinal width of the first resistance pattern is sandwiched and conveyed by the nip, the heat of the first resistance pattern is transferred to the small size through the rotating member. When transferring heat to the sheet material and sandwiching and transporting a large-sized sheet material having a sheet width corresponding to the sum of the longitudinal width of the first resistance pattern and the longitudinal width of both the second resistance patterns. A heating device characterized in that heat of the first and second resistance patterns is transferred to the large-sized sheet material via the rotating member. A fixing device comprising the heating device according to claim 17, wherein a toner image carried on the small-sized sheet material or the large-sized sheet material is passed through the nip and fixed by heating. An image forming apparatus including a paper feeding device, an image forming unit, a transfer device, and a fixing device according to claim 18.

Images