JP2021184016A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that can ensure an appropriate insulation distance between a primary circuit and a secondary circuit, while preventing the occurrence of an uneven distribution of temperature in a paper feed direction.SOLUTION: A fixing device 1 has a heater 31 and a heat sensitive body 34. The heater 31 includes a substrate 311 and a resistance heating element 312. The heat sensitive body 34 includes an element part 341, a main body part 342, an insulating film 343, and a heat conduction member 344. The element part 341 detects the temperature of the heater 31. The main body part 342 supports the element part 341 such that the element part 341 faces a non-heat generation surface 314 of the substrate 311. The insulating film 343 covers a surface of the element part 341 and part of a surface of the main body part 342. The heat conduction member 344 is interposed between the insulating film 343 and the non-heat generation surface 314. The heat conduction member 344 extends in a paper feed direction P intersecting with an axial direction M as a longitudinal direction. In the axial direction M, the width W3 of the insulating film 343 is larger than the width W2 of the heat conduction member 344.SELECTED DRAWING: Figure 5

Description

The present invention relates to a fixing device and an image forming device.

The image forming apparatus described in Patent Document 1 includes a heating belt (film) type fixing apparatus. The fixing device includes a cylindrical fixing belt, a heating unit, and a pressurizing member. The heating portion faces the inner peripheral surface of the fixing belt. The pressurizing member abuts on the outer peripheral surface of the fixing belt to pressurize the fixing belt and rotates around the rotation axis. The heating unit has a heater and a heat sensitive body. The heater extends in the longitudinal direction along the axis parallel to the axis of rotation. The heat sensitive body senses the heat of the heater.

The heater includes a substrate and a resistance heating element. The substrate has two main surfaces parallel to each other. The resistance heating element is formed on one of the two main surfaces, the heating surface, to form a primary circuit.

The heat sensitive body includes an element portion, a main body portion, an insulating film, and a heat conductive member. The element unit constitutes a secondary circuit for detecting the temperature of the heater. The main body supports the element so that the element faces the non-heat-generating surface which is the other of the two main surfaces. The insulating film covers the surface of the element portion and a part of the surface of the main body portion. The heat conductive member is interposed between the insulating film and the non-heating surface. The heat conductive member extends with the axial direction as the longitudinal direction. In the axial direction, the width of the insulating film is smaller than the length of the heat conductive member. In the region near the element portion, the length of the heat conductive member in the paper passing direction intersecting the axial direction is smaller than the length of the heat conductive member in the axial direction and smaller than the width of the substrate in the paper passing direction.

Japanese Unexamined Patent Publication No. 2017-97143

In the fixing device described in Patent Document 1, the occurrence of non-uniform distribution of temperature in the paper passing direction can be suppressed even though the heat conductive member is interposed between the non-heating surface of the substrate and the element portion of the heat sensitive body. There wasn't. As a result, the temperature detection result by the element unit varies, and the temperature of the fixing nip region between the fixing belt and the pressurizing member varies due to the heater power control based on the temperature detection result.

An object of the present invention is to provide a fixing device and an image forming device capable of ensuring an appropriate insulation distance between a primary circuit and a secondary circuit while suppressing the occurrence of non-uniform distribution of temperature in the paper passing direction. do.

The fixing device of the present invention includes a cylindrical fixing belt, a heating portion, and a pressurizing member. The heating portion faces the inner peripheral surface of the fixing belt. The pressurizing member abuts on the outer peripheral surface of the fixing belt to pressurize the fixing belt and rotates around the rotation axis. The heating unit has a heater and a heat sensitive body. The heater extends with the axial direction parallel to the rotation axis as the longitudinal direction. The heat sensitive body senses the heat of the heater. The heater includes a substrate and a resistance heating element. The substrate has two main surfaces parallel to each other. The resistance heating element is formed on one of the two main surfaces, the heating surface. The heat-sensitive body includes an element portion, a main body portion, an insulating film, and a heat conductive member. The element unit detects the temperature of the heater. The main body supports the element so that the element faces the non-heating surface which is the other of the two main surfaces. The insulating film covers the surface of the element portion and a part of the surface of the main body portion. The heat conductive member is interposed between the insulating film and the non-heating surface. The heat conductive member extends with the paper passing direction intersecting the axial direction as the longitudinal direction. In the axial direction, the width of the insulating film is larger than the width of the heat conductive member.

The image forming apparatus of the present invention includes the above-mentioned fixing device and an image forming unit. The image forming unit forms a toner image on a recording medium. The fixing device fixes the toner image on the recording medium.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a fixing device and an image forming apparatus capable of ensuring an appropriate insulation distance between a primary circuit and a secondary circuit while suppressing the occurrence of non-uniform distribution of temperature in the paper passing direction.

It is a schematic diagram which shows an example of the structure of the image forming apparatus which concerns on embodiment. It is a perspective view which shows an example of the fixing device. FIG. 2 is a cross-sectional view taken along the line III-III of FIG. It is a top view which shows the detailed structure of a heater and a heat sensitive body. FIG. 6 is a sectional view taken along line VV of FIG. FIG. 4 is a sectional view taken along line VI-VI of FIG. It is a perspective view which shows the electrical connection of a heat sensitive body.

An embodiment of the present invention will be described with reference to the drawings. In the figure, the same or corresponding parts are designated by the same reference numerals and the description is not repeated.

The image forming apparatus 100 according to the embodiment will be described with reference to FIG. FIG. 1 is a schematic view showing an example of the configuration of the image forming apparatus 100. The image forming apparatus 100 is, for example, a copying machine, a printer, a facsimile, or a multifunction device having these functions. Hereinafter, an embodiment in which the image forming apparatus 100 is a monochrome multifunction device will be described. In FIG. 1, for convenience, the direction from left to right is the positive direction of the X axis, the direction from the front to the back is the positive direction of the Y axis, and the direction from the bottom to the top is the positive direction of the Z axis. do.

As shown in FIG. 1, the image forming apparatus 100 includes a fixing device 1, an image forming unit 2, a reading unit 3, a feeding unit 4, a conveying unit 5, and an discharging unit 6.

The reading unit 3 reads the image of the document G. The reading unit 3 generates image data from the read image. The feeding section 4 accommodates a plurality of sheets S and feeds the sheets S to the transport section 5. The sheet S is made of, for example, paper or synthetic resin. The transport unit 5 includes a plurality of transport roller pairs and transports the sheet S to the image forming unit 2. The sheet S corresponds to an example of a "recording medium".

The image forming unit 2 forms a toner image on the sheet S by an electrophotographic method. The image forming unit 2 includes a photoconductor drum, a charging device, an exposure device, a developing device, a replenishing device, a transfer device, a cleaning device, and a static elimination device. The toner image shows, for example, an image of the document G. The fixing device 1 heats and pressurizes the toner image to fix the toner image on the sheet S. The transport unit 5 transports the sheet S on which the toner image is fixed to the discharge unit 6. The discharge unit 6 discharges the sheet S to the outside of the image forming apparatus 100.

Next, the configuration of the fixing device 1 will be described with reference to FIGS. 2 and 3. FIG. 2 is a perspective view showing an example of the fixing device 1. FIG. 3 is a sectional view taken along line III-III of FIG.

As shown in FIGS. 2 and 3, the fixing device 1 includes a fixing belt 10, a pressure member 20, a heating unit 30, a first belt holding member 61, and a second belt holding member 62.

The fixing belt 10 is a flexible tubular belt, and has an outer peripheral surface 101 and an inner peripheral surface 102. The pressurizing member 20 is a pressurizing roller and includes an outer peripheral surface 201 having elasticity. The outer peripheral surface 201 of the pressurizing member 20 abuts on the outer peripheral surface 101 of the fixing belt 10 to pressurize the fixing belt 10. As a result, the fixing nip region N is formed between the outer peripheral surface 101 of the fixing belt 10 and the outer peripheral surface 201 of the pressurizing member 20.

The pressurizing member 20 has a shaft core 24. In the pressurizing member 20, the shaft core 24 is driven by a drive mechanism (not shown) and rotates around the rotation axis L. The pressurizing member 20 rotates in the first counterclockwise rotation direction R1 in FIG. The fixing belt 10 is driven by the rotation of the pressurizing member 20 and rotates in the second clockwise rotation direction R2 in FIG. The sheet S moves along the paper passing direction P that intersects the axial direction M parallel to the rotation axis L so as to pass through the fixing nip region N.

The heating unit 30 includes a heater 31, a heater holding member 32, a reinforcing member 33, and a heat sensitive body 34, and faces the inner peripheral surface 102 of the fixing belt 10.

The heater 31 comes into contact with the inner peripheral surface 102 of the fixing belt 10 to heat the fixing belt 10. The heater 31 is, for example, an elongated plate-shaped ceramic heater extending in the longitudinal direction M in the axial direction.

The heater holding member 32 holds the heater 31. The heater holding member 32 is a heat-resistant resin member having a U-shaped cross section extending along the axial direction M. The heater holding member 32 preferably has a rib 321 for shaping the fixing belt 10.

The reinforcing member 33 is a metal stay member having a U-shaped cross section extending along the axial direction M. The reinforcing member 33 is combined with the heater holding member 32 so as to reinforce the heater holding member 32.

The heat sensitive body 34 abuts on the heater 31 in the through hole provided in the heater holding member 32, and senses the heat of the heater 31.

Both ends of the fixing belt 10 in the axial direction M are held by the first belt holding member 61 and the second belt holding member 62.

Next, the detailed configuration of the heater 31 and the heat sensitive body 34 will be described with reference to FIGS. 4, 5, and 6. FIG. 4 is a plan view showing a detailed configuration of the heater 31 and the heat sensitive body 34. FIG. 5 is a sectional view taken along line VV of FIG. FIG. 6 is a sectional view taken along line VI-VI of FIG.

As shown in FIGS. 4, 5, and 6, the heater 31 includes a substrate 311 and a resistance heating element 312.

The substrate 311 is, for example, a ceramic substrate. The substrate 311 has two main surfaces parallel to each other. One of the two main surfaces is the heat generation surface 313, and the other is the non-heat generation surface 314.

The resistance heating element 312 is formed on the heating surface 313 of the substrate 311 together with a wiring element (not shown). The resistance heating element 312 and the wiring body form a primary circuit.

The heat sensitive body 34 includes an element portion 341, a main body portion 342, an insulating film 343, and a heat conductive member 344.

The element unit 341 detects the temperature of the heater 31. The element unit 341 includes, for example, a thermistor.

The main body portion 342 supports the element portion 341 so that the element portion 341 faces the non-heating surface 314 of the substrate 311. The main body portion 342 has, for example, a rectangular parallelepiped shape and is made of resin. It should be noted that preferably, a cushioning member such as ceramic paper is provided between the element portion 341 and the main body portion 342.

The insulating film 343 is wound around the main body portion 342 so as to cover the surface of the element portion 341 and a part of the surface of the main body portion 342. As shown in FIG. 6, the insulating film 343 goes around the four circumferences of the main body portion 342 in a plane (ZX plane) intersecting the axial direction M. The insulating film 343 is made of, for example, polyimide.

The heat conductive member 344 is made of metal, for example, and is interposed between the insulating film 343 and the non-heating surface 314. As shown in FIG. 4, the heat conductive member 344 extends with the paper passing direction P as the longitudinal direction. That is, the length L2 of the heat conductive member 344 in the paper passing direction P is larger than the width W2 of the heat conductive member 344 in the axial direction M. Further, as shown in FIGS. 4 and 6, in the paper passing direction P, the length L2 of the heat conductive member 344 is substantially equal to the width W4 of the substrate 311.

As shown in FIGS. 4 and 5, in the axial direction M, the width W3 of the insulating film 343 is larger than the width W2 of the heat conductive member 344. Further, in the axial direction M, the width W2 of the heat conductive member 344 is larger than the width W1 of the element portion 341.

Next, the electrical connection of the heat sensitive body 34 will be described with reference to FIGS. 4, 5, 6, and 7. FIG. 7 is a perspective view showing the electrical connection of the heat sensitive body 34.

As shown in FIG. 7, the heat sensitive body 34 further includes a first jumet wire 345, a second jumet wire 346, a first terminal 347, and a second terminal 348.

One end of each of the first jumet wire 345 and the second jumet wire 346 is connected to the element portion 341. The first jumet wire 345 exits from one end of the element portion 341 in parallel with the paper passing direction P, passes between the surface of the main body portion 342 and the insulating film 343, and extends to the first terminal 347. The second jumet wire 346 exits from the other end of the element portion 341 in parallel with the paper passing direction P, passes between the surface of the main body portion 342 and the insulating film 343, and extends to the second terminal 348. The first terminal 347 and the second terminal 348 are formed on the six surfaces of the main body portion 342 that face the surface that supports the element portion 341. Most of the first jumet wire 345 and the second jumet wire 346 are covered with the insulating film 343. Wiring 349 is connected to the first terminal 347 and the second terminal 348. The element unit 341, the first jumet wire 345, the second jumet wire 346, the first terminal 347, the second terminal 348, and the wiring 349 form a secondary circuit. The first jumet wire 345 and the second jumet wire 346 correspond to an example of a “wiring member”.

As shown in FIGS. 4 and 6, in the paper passing direction P, the length L2 of the heat conductive member 344 is substantially equal to the width W4 of the substrate 311. Therefore, the occurrence of non-uniform temperature distribution in the paper passing direction P is suppressed. Moreover, as shown in FIGS. 4 and 5, the width W2 of the heat conductive member 344 is larger than the width W1 of the element portion 341 in the axial direction M. Therefore, even in the axial direction M, the occurrence of non-uniform temperature distribution is suppressed in a certain region.

On the other hand, since the heat conductive member 344 has conductivity, it is disadvantageous for the insulation design to increase the width W2 of the heat conductive member 344 in the axial direction M. However, as shown in FIGS. 4 and 5, the width W2 of the heat conductive member 344 is smaller than the width W3 of the insulating film 343 in the axial direction M. Therefore, the insulation was maintained by a long path from the edge extending along the Z-axis direction (paper-passing direction P) of the heat conductive member 344 to the element portion 341 through one surface and the other surface of the insulating film 343 in sequence. Is done. That is, an appropriate insulation distance between the primary circuit and the secondary circuit is ensured. Further, the insulation distance from the primary circuit to the element portion 341 is not shortened by the presence of the first jumet wire 345 and the second jumet wire 346.

According to the embodiment, the fixing device 1 and the image forming device 100 capable of ensuring an appropriate insulation distance between the primary circuit and the secondary circuit while suppressing the occurrence of non-uniform distribution of temperature in the paper passing direction P are provided. Will be done.

The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiment, and can be implemented in various embodiments without departing from the gist thereof. In addition, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiments. For example, some components may be removed from all the components shown in the embodiments. In order to make the drawings easier to understand, each component is schematically shown, and the number of each component shown may differ from the actual one due to the convenience of drawing. Further, each component shown in the above embodiment is an example, and is not particularly limited, and various changes can be made without substantially deviating from the effect of the present invention.

The present invention can be used in the fields of fixing devices and image forming devices.

1 Fixing device 2 Image forming part 10 Fixing belt 20 Pressurizing member 30 Heating part 31 Heater 34 Heat sensitive body 100 Image forming device 101 Outer peripheral surface 102 Inner peripheral surface 201 Outer peripheral surface 3 11 Substrate 312 Resistor heating element 313 Heating surface 314 Non-heating surface 341 Element part 342 Main body part 343 Insulation film 344 Heat conduction member 345 First Jumet wire (wiring member)
346 2nd Jumet wire (wiring member)
L Rotating axis M Axial direction N Fixing nip area P Paper passing direction S Sheet (recording medium)

Claims (5)

With a tubular fixing belt,
The heating portion facing the inner peripheral surface of the fixing belt and
It is provided with a pressurizing member that abuts on the outer peripheral surface of the fixing belt to pressurize the fixing belt and rotates around the rotation axis.
The heating part is
A heater that extends in the longitudinal direction along the axis parallel to the rotation axis,
It has a heat sensitive body that senses the heat of the heater.
The heater is
A substrate having two main surfaces parallel to each other,
Includes a resistance heating element formed on one of the two main surfaces, the heating element.
The heat sensitive body is
The element unit that detects the temperature of the heater and
A main body portion that supports the element portion so that the element portion faces the non-heating surface that is the other of the two main surfaces, and a main body portion.
An insulating film that covers the surface of the element portion and a part of the surface of the main body portion,
Includes a heat conductive member interposed between the insulating film and the non-heating surface.
The heat conductive member extends with the paper passing direction intersecting the axial direction as the longitudinal direction.
A fixing device in which the width of the insulating film is larger than the width of the heat conductive member in the axial direction. The fixing according to claim 1, wherein the length of the heat conductive member in the paper passing direction is larger than the width of the heat conductive member in the axial direction and substantially equal to the width of the substrate in the paper passing direction. Device. The fixing device according to claim 1 or 2, wherein the width of the heat conductive member is larger than the width of the element portion in the axial direction. The heat sensitive body further includes a wiring member connected to the element portion, and the heat sensitive body further includes a wiring member.
The fixing according to any one of claims 1 to 3, wherein the wiring member exits from the element portion in parallel with the paper passing direction and passes between the surface of the main body portion and the insulating film. Device. The fixing device according to any one of claims 1 to 4, and the fixing device.
The recording medium is provided with an image forming unit that forms a toner image.
The fixing device is an image forming device that fixes the toner image on the recording medium.

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