JP6950348B2 - Temperature detection device, fixing device, image forming device - Google Patents

Description

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

The temperature detection device described in Patent Document 1 encloses a heat-sensitive element, a heat-sensitive element holder having excellent thermal conductivity and heat resistance, a sponge-like elastic body that supports the heat-sensitive element holder, and rotationally heats them. It is equipped with a heat-resistant insulating film with a low coefficient of friction that makes smooth contact with the body.

Japanese Unexamined Patent Publication No. 8-54295

The temperature detection device includes a heat-sensitive element such as a thermistor, and a contact member that comes into contact with the heat-sensitive element and suppresses the heat transferred from the detection target member to the heat-sensitive element from being released from the heat-sensitive element. Here, when the liquid is attached to the detection target member, the contact member absorbs the liquid, and the liquid comes into contact with the heat-sensitive element, so that the responsiveness of the temperature detection device is lowered.

An object of the present invention is to suppress a decrease in the responsiveness of the temperature detection device as compared with the case where the water absorption of the contact member in contact with the heat sensitive element is constant regardless of the portion constituting the contact member. Is.

The temperature detection device according to claim 1 of the present invention is a contact member that is in contact with the heat-sensitive element and the heat-sensitive element, and the water absorption of a portion close to the heat-sensitive element is reduced with respect to the heat-sensitive element. The contact member is provided with the contact member, which is lower than the water absorption of the separated portion, and the contact member is formed of a plurality of sheet members stacked in the contact direction in contact with the heat sensitive element and has a gap. Then, the number of laminated sheet members per unit thickness of the close portion is increased as compared with the number of laminated sheets per unit thickness of the separated portion, and the porosity of the close portion is the porosity of the separated portion. It is characterized by being low compared to.

The temperature detection device according to claim 2 of the present invention is the temperature detection device according to claim 1 , wherein the contact member is formed of a plurality of sheet members stacked in a contact direction in contact with the heat sensitive element. It is characterized in that the mass per unit thickness of the adjacent portion is larger than the mass per unit thickness of the separated portion.

The temperature detection device according to claim 3 of the present invention is the temperature detection device according to claim 1 , wherein the contact member is formed of a plurality of layers laminated in a contact direction in contact with the heat sensitive element. It is characterized in that the porosity of the proximity layer constituting the proximity portion is lower than the porosity of the separation layer constituting the separation portion.

The temperature detection device according to claim 4 of the present invention is the temperature detection device according to claim 3 , and includes a support member that is arranged on the opposite side of the heat sensitive element with the contact member in between and supports the contact member. The support member is characterized in that it supports the contact member in a non-contact state with the proximity layer.

The temperature detection device according to claim 5 of the present invention is the temperature detection device according to any one of claims 1 to 4 , wherein the cover film covering the heat sensitive element and the contact member, and the cover film and the contact. It is characterized by including a conductive portion which is arranged between the members and for applying a voltage to the heat sensitive element.

The temperature detection device according to claim 6 of the present invention is the temperature detection device according to any one of claims 1 to 5 , further comprising the heat sensitive element and a covering film covering the contact member, and the contact member comprises the heat sensitive element and a covering film covering the contact member. The contact member is larger than the thermal element when viewed from the contact direction in contact with the thermal element, and when viewed from the contact direction, the contact member and the covering film are between the contact member and the covering film. It is characterized in that a gap is formed to sandwich the heat sensitive element from one direction.

The temperature detection device according to claim 7 of the present invention is the temperature detection device according to claim 6 , wherein the gap is formed so as to surround the heat sensitive element when viewed from the contact direction. do.

The fixing device according to claim 8 of the present invention has a cylindrical shape, and a cylindrical member to which a liquid is applied to an inner peripheral surface and circulates, and a heat generating member that generates heat to heat a part of the inner peripheral surface of the cylindrical member. The temperature detection device according to any one of claims 1 to 7 , which detects the temperature of the heat-generating member, and the outer peripheral surface of the cylindrical member, which is arranged on the opposite side of the heat-generating member with the cylindrical member interposed therebetween. It is characterized by including a pressurizing member that pressurizes a recording medium on which an image is transferred.

The image forming apparatus according to claim 9 of the present invention is characterized by including an image forming unit for forming an image on a recording medium and a fixing device according to claim 8 for fixing the image on a recording medium.

According to the temperature detection device of claim 1 of the present invention, the water absorption of the contact member in contact with the heat-sensitive element is constant regardless of the portion constituting the contact member, as compared with the case where the temperature detection device is used. It is possible to suppress a decrease in responsiveness.

Further, it is possible to suppress a decrease in the responsiveness of the temperature detection device as compared with the case where the porosity of the contact member is constant regardless of the portion constituting the contact member.

Further, as compared with the case where the number of sheet members forming the contact member is the same and the number of laminated sheet members per unit thickness of the contact member is constant regardless of the portion constituting the contact member. , It is possible to suppress a decrease in the responsiveness of the temperature detection device.

According to the temperature detection device of claim 2 of the present invention, the mass of the contact member is the same, and the mass per unit thickness of the contact member is constant regardless of the portion constituting the contact member. In comparison, it is possible to suppress a decrease in the responsiveness of the temperature detection device.

According to the temperature detection device of claim 3 of the present invention, the porosity can be easily changed as compared with the case where the porosity is changed in the same layer.

According to the temperature detection device of claim 4 of the present invention, it is possible to suppress a decrease in the responsiveness of the temperature detection device as compared with the case where the support member is in contact with the adjacent layer.

According to the temperature detection device of claim 5 of the present invention, it is possible to suppress a decrease in the responsiveness of the temperature detection device as compared with the case where the conductive portion is arranged inside the contact member.

According to the temperature detection device of claim 6 of the present invention, the responsiveness of the temperature detection device is higher than that in the case where the contact member and the covering film are in contact with each other on the entire circumference of the heat sensitive element when viewed from the contact direction. The decrease can be suppressed.

According to the temperature detection device of claim 7 of the present invention, only a pair of gaps are formed between the contact member and the covering film so as to sandwich the heat sensitive element from one direction when viewed from the contact direction. In comparison, it is possible to suppress a decrease in the responsiveness of the temperature detection device.

According to the fixing device of claim 8 of the present invention, the water absorption of the contact member in contact with the heat sensitive element is higher than that of the case where the contact member is provided with a constant temperature detection device regardless of the portion constituting the contact member. Therefore, it is possible to quickly detect that the temperature of the heat generating member has reached a specified temperature.

According to the image forming apparatus of claim 9 of the present invention, the water absorption of the contact member in contact with the heat sensitive element is higher than that of the case where the contact member is provided with a constant temperature detection device regardless of the portion constituting the contact member. Therefore, it is possible to speed up the output of the first image after operating the image forming apparatus in the non-operating state.

(A) (B) It is sectional drawing which showed the temperature detection apparatus which concerns on 1st Embodiment of this invention. It is an enlarged sectional view which showed the fixing apparatus which concerns on 1st Embodiment of this invention. (A) (B) It is a perspective view which showed the temperature detection apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the fixing apparatus which concerns on 1st Embodiment of this invention. It is a top view which showed the planar heating element of the fixing device which concerns on 1st Embodiment of this invention. It is a block diagram which showed the control system of the control part provided in the image forming apparatus which concerns on 1st Embodiment of this invention. It is a schematic block diagram which showed the image forming apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the temperature detection apparatus which concerns on the comparative embodiment with respect to 1st Embodiment of this invention. It is a perspective view which showed the temperature detection apparatus which concerns on 2nd Embodiment of this invention. It is a perspective view which showed the temperature detection apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing which showed the temperature detection apparatus which concerns on 3rd Embodiment of this invention. It is a perspective view which showed the temperature detection apparatus which concerns on 4th Embodiment of this invention. It is sectional drawing which showed the temperature detection apparatus which concerns on 4th Embodiment of this invention.

<First Embodiment>
An example of the temperature detection device, the fixing device, and the image forming device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 8. The arrow H shown in the figure indicates the device vertical direction (vertical direction), the arrow W indicates the device width direction (horizontal direction), and the arrow D indicates the device depth direction (horizontal direction).

(overall structure)
As shown in FIG. 7, in the image forming apparatus 10 according to the present embodiment, the accommodating portion 14 in which the recording medium P is accommodated and the accommodating portion 14 are accommodated in the vertical direction (arrow H direction) from the lower side to the upper side. A transport unit 16 that conveys the recording medium P housed in the storage unit P, and an image forming unit 20 that forms an image on the recording medium P conveyed from the storage unit 14 by the transport unit 16 are provided in this order. Further, the image forming apparatus 10 is provided with a control unit 48 that controls each unit.

[Accommodation]
The accommodating portion 14 is provided with an accommodating member 14A that can be pulled out from the apparatus main body 10A of the image forming apparatus 10 toward the front side in the depth direction of the apparatus, and the recording medium P is loaded on the accommodating member 14A. Further, the accommodating portion 14 is provided with a delivery roll 14B that sends the recording medium P loaded on the accommodating member 14A to the transport path 28 constituting the transport unit 16.

[Transport section]
The transport unit 16 is provided with a plurality of transport rolls (reference numerals omitted) for transporting the recording medium P along the transport path 28 to which the recording medium P sent out from the accommodating unit 14 is transported.

[Image forming part]

The image forming unit 20 includes an image forming unit 18 that forms a black (K) toner image, and a transfer roll 46 that transfers the toner image formed by the image forming unit 18 to a sheet member. Further, the image forming unit 20 is provided with a fixing device 50 that heats and pressurizes the recording medium P on which the toner image is transferred to fix the toner image on the recording medium P.

The image forming unit 18 includes an image holder 36, a charging member 38 that charges the surface of the image holder 36, and an exposure device that irradiates the surface of the charged image holder 36 with exposure light to form an electrostatic latent image. 40 and a developing device 42 that develops an electrostatic latent image and visualizes it as a toner image are provided.

The details of the fixing device 50 will be described later.

(Action of image forming device)
In the image forming apparatus 10, an image is formed as follows.

First, the charging member 38 to which the voltage is applied uniformly negatively charges the surface of the image holder 36 at a predetermined potential. Subsequently, the exposure apparatus 40 irradiates the surface of the charged image holder 36 with exposure light based on the image data received from the outside to form an electrostatic latent image.

As a result, an electrostatic latent image corresponding to the data is formed on the surface of the image holder 36. Further, the developing device 42 develops this electrostatic latent image and visualizes it as a toner image.

Therefore, the recording medium P sent from the accommodating member 14A to the transfer path 28 by the delivery roll 14B is sent to the transfer position T where the image holder 36 and the transfer roll 46 come into contact with each other. At the transfer position T, the recording medium P is conveyed between the image holder 36 and the transfer roll 46, so that the toner image on the surface of the image holder 36 is transferred to the recording medium P.

The toner image transferred to the recording medium P is fixed to the recording medium P by the fixing device 50. Then, the recording medium P on which the toner image is fixed is discharged to the outside of the apparatus main body 10A.

(Main part composition)
Next, the configuration of the fixing device 50 will be described.

As shown in FIG. 4, the fixing device 50 includes a pressurizing unit 52 and a heating unit 60 facing the pressurizing unit 52 in the device width direction.

[Pressurizing unit 52]
The pressurizing portion 52 includes a metal shaft portion 54 extending in the depth direction of the device, a cylindrical elastic layer 56 through which the shaft portion 54 penetrates, and a mold release layer 58 covering the elastic layer 56. .. The shaft portion 54 is formed of, for example, a metal material such as steel, stainless steel, or aluminum, the elastic layer 56 is formed of, for example, a rubber material, and the release layer 58 is formed of, for example, ethylene fluoride-. It is formed from a perfluoroalkoxy alkaneethylene copolymer (PFA) or the like. The pressurizing unit 52 is an example of a pressurizing member.

The pressurizing portion 52 is grounded and is urged to the heating portion 60 side by an urging member (not shown). As a result, the pressurizing unit 52 pressurizes the seed member P to which the image is transferred onto the outer peripheral surface of the endless belt 62, which will be described later. Further, the pressurizing unit 52 is adapted to rotate in the direction of arrow A in the drawing by transmitting a rotational force from a motor (not shown).

[Heating unit 60]
As shown in FIGS. 2 and 4, the heating unit 60 includes a cylindrical endless belt 62 extending in the depth direction of the device and a planar heating element 64 that generates heat to heat the endless belt 62. Further, the heating unit 60 includes a holding member 68 that holds the planar heating element 64, a frame member 72 that supports the holding member 68, and a temperature detection device 80 that detects the temperature of the planar heating element 64. ing. The endless belt 62 is an example of a cylindrical member, and the planar heating element 64 is an example of a heating member.

-Endless belt 62-
The endless belt 62 is formed, for example, in a multi-layer structure. Further, circular support members (not shown) that support the inner peripheral surface 62A of the endless belt 62 are arranged at both ends of the endless belt 62 in the longitudinal direction. As a result, the endless belt 62 orbits in the direction of arrow B in the drawing while maintaining a circular shape.

Further, the inner peripheral surface 62A of the endless belt 62 is in a state of being coated with lubricating oil S (an example of a liquid, for example, silicon oil) in order to reduce frictional resistance with the planar heating element 64.

−Spanic heating element 64-
The planar heating element 64 is arranged inside the endless belt 62 and on the opposite side of the pressurizing portion 52 with the endless belt 62 interposed therebetween. The planar heating element 64 is a plate-shaped member whose plate surface faces the device width direction, and extends from one end to the other end of the endless belt 62 in the device depth direction. When viewed from the plate thickness direction, the planar heating element 64 has a rectangular shape extending in the device width depth direction as shown in FIG.

The planar heating element 64 has an electrically insulating base material 64A, an insulating layer 64B made of a heat-resistant resin material, and a pair of electrodes 64C for applying a voltage. Further, the planar heating element 64 is a pair of a plurality of resistance heating elements 64D that generate heat when a voltage is applied to the electrodes 64C, and a pair that electrically connects each electrode 64C and both ends of the resistance heating element 64D. It has a connection portion 64E. The electrode 64C, the resistance heat generating portion 64D, and the connecting portion 64E are formed on the base material 64A, and the resistance heating portion 64D and the connecting portion 64E are covered with the insulating layer 64B from the opposite side of the base material 64A. ..

Further, the image forming apparatus 10 includes an application member 76 (see FIG. 6) that applies a voltage to the pair of electrodes 64C.

In this configuration, when a voltage is applied to the pair of electrodes 64C by the application member 76 (see FIG. 6), the planar heating element 64 generates heat.

-Holding member 68-
As shown in FIG. 2, the holding member 68 is arranged inside the endless belt 62 and on the opposite side of the pressurizing portion 52 with the planar heating element 64 interposed therebetween. The holding member 68 is made of, for example, a resin material such as LCP (liquid crystal polymer) having high heat resistance, and extends in the depth direction of the device. The cross section of the holding member 68 orthogonal to the longitudinal direction is U-shaped with the planar heating element 64 side open.

Specifically, the holding member 68 is formed to include a pair of side plates 68A whose plate surfaces face in the vertical direction and face each other in the vertical direction, and a bottom plate 68B connecting the base ends of the pair of side plates 68A. The tip of the pair of side plates 68A is fixed to the planar heating element 64 by a fixture (not shown), so that the holding member 68 holds the planar heating element 64. Further, in this state, the bottom plate 68B of the holding member 68 and the planar heating element 64 are separated from each other in the device width direction and face each other.

-Frame member 72-
The frame member 72 is arranged on the opposite side of the planar heating element 64 with the holding member 68 interposed therebetween. The frame member 72 is made of, for example, a metal material and extends in the depth direction of the device. The cross section of the frame member 72 orthogonal to the longitudinal direction is U-shaped with the holding member 68 side open. Further, both ends of the U-shaped frame member 72 are fixed to the holding member 68 by a fixture (not shown), so that the frame member 72 supports the holding member 68.

Further, both ends of the frame member 72 in the longitudinal direction protrude outward from the endless belt 62, and the protruding portions are fixed to a skeleton member (not shown) of the fixing device 50.

-Temperature detection device 80-
The temperature detection device 80 is a surface between the bottom plate 68B of the holding member 68 and the planar heating element 64 as shown in FIG. 2 and in the device depth direction as shown in FIG. 3 (A). It is arranged in the central portion of the heating element 64. The temperature detection device 80 is fixed to the bottom plate 68B of the holding member 68 with a fixture (not shown).

Then, as shown in FIGS. 1 (A) and 3 (B), the temperature detection device 80 comes into contact with the heat sensitive element 82 and the heat sensitive element 82 to suppress heat from being released from the heat sensitive element 82. It has a contact member 84 and a support member 92 that supports the contact member 84. Further, the temperature detection device 80 includes a pair of electric wires 94 for applying a voltage to the heat sensitive element 82, and an insulating film 96 that covers a part of the electric wires 94, the heat sensitive element 82, and the contact member 84. The electric wire 94 is an example of a conductive portion, and the insulating film 96 is an example of a covering film.

The heat sensitive element 82 is arranged on the opposite side of the planar heating element 64 with the insulating film 96 interposed therebetween. The heat-sensitive element 82 is, for example, a thermistor whose electrical resistance (resistance value) changes according to temperature, and has a circular plate shape. The plate thickness direction of the heat sensitive element 82 is the device width direction.

The contact member 84 is arranged on the opposite side of the planar heating element 64 with the heat sensitive element 82 interposed therebetween, and is in contact with the heat sensitive element 82 from the width direction of the device. That is, in the present embodiment, the contact direction in which the contact member 84 contacts the heat sensitive element 82 is the device width direction. The contact member 84 extends in the depth direction of the device as shown in FIG. 3 (B), and is in contact with the heat sensitive element 82 when viewed from the depth direction of the device as shown in FIG. 1 (A). (Surface heating element 64 side) is semicircular. The heat sensitive element 82 described above is in contact with a portion of the contact member 84 on the central side in the depth direction of the device. The contact member 84 is made larger than the heat sensitive element 82 when viewed from the width direction of the device.

The contact member 84 is formed of a plurality of sheet members 86 stacked in the device width direction (contact direction). The sheet member 86 is, for example, a highly flame-retardant ceramic paper formed by containing ceramics and pulp.

Further, the contact member 84 is composed of a proximity portion 84A that is close to the heat sensitive element 82 and a separation portion 84B that is separated from the heat sensitive element 82. In the present embodiment, as an example, the thickness of the proximity portion 84A and the thickness of the separation portion 84B in the device width direction are the same.

Further, the number of laminated sheet members 86 per unit thickness of the proximity portion 84A is larger than the number of laminated sheet members 86 per unit thickness of the separated portion 84B. In other words, the mass per unit thickness of the proximity portion 84A is larger than the mass per unit thickness of the separation portion 84B. In other words, the density of the proximity portion 84A is increased as compared with the density of the separation portion 84B. In other words, with respect to the porosity of the gap generated between the seat member 86 and the seat member 86, the porosity of the proximity portion 84A is lower than the porosity of the separation portion 84B.

The "porosity" is the ratio of voids per apparent unit volume, and is calculated by the following formula (1).

Porosity = {(unit volume)-(volume of sheet member 86 in unit volume)} / (unit volume) ... Equation (1)

Therefore, the water absorption of the proximity portion 84A is lower than that of the separation portion 84B. The water absorption can be evaluated by using the water absorption test method of JIS-L-1907.

When manufacturing the contact member 84, the portion to be the proximity portion 84A and the portion to be the separation portion 84B are separately molded, and the proximity portion 84A and the separation portion 84B are overlapped with each other. Further, in order to change the number of laminated sheet members 86 per unit thickness, the pressing force applied to the sheet member 86 when laminating the sheet member 86 of the proximity portion 84A is applied to the sheet member 86 of the separation portion 84B. It is made stronger than the pressing force applied to the seat member 86.

As shown in FIG. 1A, the support member 92 is arranged on the opposite side of the heat sensitive element 82 with the contact member 84 in the device width direction. The support member 92 is made of, for example, a resin material such as LCP (liquid crystal polymer) having high heat resistance, and has a rectangular parallelepiped shape extending in the depth direction of the device. The support member 92 supports the contact member 84 from the width direction of the device.

The insulating film 96 covers the heat sensitive element 82, the contact member 84, and the support member 92 when viewed from the depth direction of the device. Specifically, the insulating film 96 covers (covers) the heat sensitive element 82, the contact member 84, and the support member 92 from the planar heating element 64 side, and both ends of the insulating film 96 are supported. The side surfaces of the member 92 face each other in the vertical direction. The end face of the contact member 84 in the depth direction of the device is not covered with the insulating film 96. The insulating film 96 is, for example, a film formed of a polyimide resin (polyimide), which has high heat resistance and insulating properties. “Insulation” means that the volume resistivity is 10 ¹³ Ωcm or more.

As shown in FIG. 3B, the pair of electric wires 94 are connected to a curved portion 94A that extends in a curved shape from both ends in the vertical direction of the heat sensitive element 82 and then becomes linear, and a tip of the curved portion 94A. It has a straight portion 94B extending linearly in the depth direction of the device. The curved portion 94A and the base end portion (the portion on the curved portion 94A side) of the straight portion 94B are arranged between the contact member 84 and the insulating film 96, and the tip portion of the straight portion 94B is the insulating film 96. It is exposed to the outside of.

Then, as shown in FIG. 1 (B), a gap 88 in which the insulating film 96 is separated from the contact member 84 is provided on both ends of the electric wire 94 arranged between the contact member 84 and the insulating film 96. Is formed.

〔others〕
As shown in FIG. 6, the control unit 48 (see FIG. 7) provided in the image forming apparatus 10 applies a voltage to the planar heating element 64 based on the detection result of the temperature detecting apparatus 80. Is designed to control. The control of the application member 76 by the control unit 48 will be described together with the operations described later.

(Action)
Next, the operations of the fixing device 50 and the control unit 48 will be described while comparing with the fixing device 550 according to the comparative form. First, the fixing device 550 according to the comparative form will be mainly described with respect to the parts different from the fixing device 50.

-Fixing device 550-
The fixing device 550 includes a pressurizing unit 52 and a heating unit 552. The heating unit 552 includes an endless belt 62, a planar heating element 64, a holding member 68, a frame member 72, and a temperature detection device 580 that detects the temperature of the planar heating element 64.

As shown in FIG. 8, the temperature detection device 580 includes a heat sensitive element 82, a contact member 584 that comes into contact with the heat sensitive element 82 and suppresses heat from being released from the heat sensitive element 82, and a support member 92. doing. Further, the temperature detection device 580 includes a pair of electric wires 94 (see FIG. 3B) for applying a voltage to the heat sensitive element 82, and an insulating film 96.

The contact member 584 is arranged on the opposite side of the planar heating element 64 with the heat sensitive element 82 interposed therebetween, and is in contact with the heat sensitive element 82 from the width direction of the device. The contact member 584 has a rectangular shape extending in the device width direction when viewed from the device depth direction, and has a semicircular shape on the side in contact with the heat sensitive element 82 (the planar heating element 64 side).

The contact member 584 is formed of a plurality of sheet members 86 stacked in the device width direction (contact direction). Further, the number of sheet members 86 forming the contact member 584 and the number of sheet members 86 forming the contact member 84 are the same.

Further, the number of laminated sheet members 86 per unit thickness of the contact member 584 is constant regardless of the portion constituting the contact member 584. In other words, the porosity of the gap generated between the seat member 86 and the seat member 86 is constant regardless of the portion constituting the contact member 584. In other words, the mass per unit thickness of the contact member 584 is constant regardless of the portion constituting the contact member 584. In other words, the density of the contact member 584 is constant regardless of the portion constituting the contact member 584. In other words, the water absorption of the contact member 584 is constant regardless of the portion constituting the contact member 584.

-Action of fixing device 50, 550-
Next, the operations of the fixing devices 50, 550 and the control unit 48 will be described. The operation of the fixing device 550 will be mainly described as being different from the fixing device 50. Before the fixing device 50 operates, no voltage is applied to the planar heating element 64, and the pressurizing unit 52 is stopped.

When the toner image transferred to the recording medium P is fixed to the recording medium P, the pressurizing unit 52 transmits the rotational force from a motor (not shown), and as shown in FIG. 4, the direction of arrow A in the drawing. Rotate to. As a result, the endless belt 62 that comes into contact with the pressurizing portion 52 is driven by the rotating pressurizing portion 52 and orbits in the direction of arrow B in the drawing.

Further, a voltage is applied to the pair of electrodes 64C (see FIG. 5) by the application member 76 (see FIG. 6). As a result, the planar heating element 64 generates heat, and the rotating endless belt 62 is heated from the inner peripheral surface 62A.

Further, a predetermined voltage is applied to the pair of electric wires 94 (see FIG. 3B) of the temperature detection devices 80 and 580 from an application means (not shown). Then, the control unit 48 (see FIG. 6) detects the temperature of the planar heating element 64 based on the resistance value of the heat sensitive element 82 by the voltage detected from the electric wire 94. In the present embodiment, as an example, the control unit 48 turns on and off the application member 76 so that the temperature of the planar heating element 64 is 190 [° C.] or more and 230 [° C.] or less.

Then, after the temperature of the planar heating element 64 reaches 190 [° C.] or higher, the recording medium P on which the toner image is transferred passes between the heating unit 60 and the pressurizing unit 52. As a result, the toner image transferred to the recording medium P is fixed on the recording medium P.

Here, as described above, the inner peripheral surface 62A of the endless belt 62 is coated with the lubricating oil S in order to reduce the frictional resistance with the planar heating element 64. Therefore, the lubricating oil S applied to the inner peripheral surface 62A of the rotating endless belt 62 flies in the endless belt 62 in a mist form and adheres to the contact members 84 and 584 of the temperature detection devices 80 and 580 to come into contact with each other. It is absorbed by members 84 and 584.

The water absorption of the contact member 584 provided in the temperature detection device 580 according to the comparative embodiment is constant regardless of the portion constituting the contact member 584. Therefore, the lubricating oil S adhering to the contact member 584 is uniformly (evenly) absorbed by the contact member 584. Then, when the heat sensitive element 82 of the temperature detection device 580 comes into contact with the lubricating oil S absorbed by the contact member 584, the heat of the heat sensitive element 82 is transferred to the lubricating oil S, and the responsiveness of the temperature detection device 580 deteriorates. It ends up.

On the other hand, regarding the water absorption of the contact member 84 provided in the temperature detection device 80 of the present embodiment, the water absorption of the proximity portion 84A is lower than the water absorption of the separation portion 84B. Therefore, the absorption amount of the lubricating oil S per unit volume in the proximity portion 84A is smaller than the absorption amount of the lubricating oil S per unit volume in the separation portion 84B.

(summary)
As described above, in the temperature detection device 80, the absorption amount of the lubricating oil S per unit volume in the proximity portion 84A is smaller than the absorption amount of the lubricating oil S per unit volume in the separation portion 84B. The heat sensitive element 82 is in contact with the proximity portion 84A. Therefore, the decrease in the responsiveness of the temperature detection device 80 is suppressed as compared with the case where the heat sensitive element 82 comes into contact with the contact member 584 that uniformly (evenly) absorbs the lubricating oil S.

The following method is used as an example for evaluating the responsiveness of the temperature detection device 80.

First, the endless belt 62 to which the lubricating oil S is not applied is circulated on the inner peripheral surface 62A, and a constant voltage is applied to the planar heating element 64 for a certain period of time. Further, the temperature transitions of the planar heating elements 64 detected by the temperature detection devices 80 and 580 are graphed respectively.

Next, the endless belt 62 coated with a constant amount of lubricating oil S is circulated on the inner peripheral surface 62A, and a constant voltage is applied to the planar heating element 64 for a certain period of time. Further, the temperature transitions of the planar heating elements 64 detected by the temperature detection devices 80 and 580 are graphed respectively.

Then, the temperature transition when the endless belt 62 in which the lubricating oil S is not applied to the inner peripheral surface 62A and the endless belt 62 in which a certain amount of the lubricating oil S is applied to the inner peripheral surface 62A are used. Compare with temperature transition. Specifically, the temperatures after a certain period of time are compared. As a result, the decrease in responsiveness of the temperature detection devices 80 and 580 is evaluated.

Further, gaps 88 are formed on both ends of the electric wire 94 arranged between the contact member 84 and the insulating film 96 by separating the insulating film 96 from the contact member 84 (FIG. 1 (B)). reference). Therefore, a part of the lubricating oil S absorbed by the contact member 84 exudes from the contact member 84 and is captured in the gap 88. Therefore, the amount of the lubricating oil S absorbed by the contact member 84 is reduced, and the decrease in the responsiveness of the temperature detection device 80 is suppressed.

That is, by arranging the electric wire 94 between the contact member 84 and the insulating film 96, a gap 88 is formed in which the insulating film 96 is separated from the contact member 84. By forming the gap 88, a decrease in the responsiveness of the temperature detection device 80 is suppressed as compared with the case where the electric wire is arranged inside the contact member 84.

Further, in the fixing device 50, the temperature of the planar heating element 64 becomes 230 [° C.] (specified temperature) as compared with the fixing device 550 by suppressing the decrease in the responsiveness of the temperature detecting device 80. Reached is detected quickly.

Further, in the image forming apparatus 10, the decrease in the responsiveness of the temperature detecting apparatus 80 is suppressed, so that the image forming apparatus 10 in the non-operating state is operated as compared with the case where the fixing apparatus 550 is provided. The output of the first image becomes faster.

<Second Embodiment>
Next, an example of the temperature detection device, the fixing device, and the image forming device according to the second embodiment of the present invention will be described with reference to FIG. In addition, about 2nd Embodiment, the part different from 1st Embodiment will be mainly described.

As shown in FIG. 9, the heating unit 252 in the fixing device 250 of the image forming device 210 of the second embodiment includes a temperature detecting device 280. The temperature detection device 280 has a heat sensitive element 82, a contact member 284 that comes into contact with the heat sensitive element 82 and suppresses heat from being released from the heat sensitive element 82, and a support member 92. Further, the temperature detection device 280 includes a pair of electric wires 94 for applying a voltage to the heat sensitive element 82 and an insulating film 96.

The contact member 284 extends in the depth direction of the device, and the side in contact with the heat sensitive element 82 (side of the planar heating element 64) is formed in a semicircular shape when viewed from the depth direction of the device. The contact member 284 is formed of a plurality of (two in the present embodiment) layers laminated in the device width direction (contact direction), and is in close proximity to the thermal element 82 with the proximity layer 284A. It has a separation layer 284B that is separated from the heat sensitive element 82. Further, the support member 92 supports the contact member 284 in a non-contact state with the proximity layer 284A.

The proximity layer 284A and the separation layer 284B are silicone rubber sponges (silicon rubber foams) having voids inside. The porosity of the proximity layer 284A is lower than the porosity of the separation layer 284B. In other words, the water absorption of the proximity layer 284A is lower than that of the separation layer 284B. Further, in other words, the heat insulating property of the separating layer 284B is higher than the heat insulating property of the adjacent layer 284A.

The "porosity" is the ratio of voids per apparent unit volume, and is calculated by the following formula (2).

Porosity = {(unit volume)-(volume of silicon rubber in unit volume)} / (unit volume) ... Equation (2)

As described above, the contact member 284 is formed from the proximity layer 284A and the separation layer 284B, so that the porosity is changed. Therefore, the porosity can be easily changed as compared with the case where the porosity is changed in the same layer.

Further, as described above, the heat insulating property of the separating layer 284B is higher than the heat insulating property of the adjacent layer 284A. Further, the support member 92 supports the contact member 284 in a non-contact state with the proximity layer 284A. In other words, the support member 92 supports the contact member 284 only in contact with the separation layer 284B. Therefore, the heat of the heat sensitive element 82 is suppressed from flowing to the support member 92 as compared with the case where the support member 92 is in contact with the proximity layer 284A. As a result, the decrease in the responsiveness of the temperature detection device 280 is suppressed.

The other actions of the second embodiment are the same as those of the first embodiment.

<Third Embodiment>
Next, an example of the temperature detection device, the fixing device, and the image forming device according to the third embodiment of the present invention will be described with reference to FIGS. 10 and 11. In addition, about the 3rd Embodiment, the part different from the 2nd Embodiment will be mainly described.

As shown in FIG. 10, the heating unit 352 in the fixing device 350 of the image forming device 310 of the third embodiment includes a temperature detecting device 380. The temperature detection device 380 has a heat sensitive element 82, a contact member 384 that comes into contact with the heat sensitive element 82 and suppresses heat from being released from the heat sensitive element 82, and a support member 92. Further, the temperature detection device 380 includes a pair of electric wires 94 for applying a voltage to the heat sensitive element 82, and an insulating film 96.

The contact member 384 extends in the depth direction of the device, and the side in contact with the heat sensitive element 82 (side of the planar heating element 64) is formed in a semicircular shape when viewed from the depth direction of the device. The contact member 384 is formed of a plurality of (two in the present embodiment) layers laminated in the device width direction (contact direction), and is in close proximity to the heat sensitive element 82 with the proximity layer 384A. It has a separation layer 384B that is separated from the heat sensitive element 82.

The proximity layer 384A and the separation layer 384B are silicone rubber sponges (silicon rubber foams) having voids inside. The porosity of the proximity layer 384A is lower than the porosity of the separation layer 384B. In other words, the water absorption of the proximity layer 384A is lower than that of the separation layer 384B.

Further, when viewed from the device width direction, a pair of gaps 390 are formed between the contact member 384 and the insulating film 96 so as to sandwich the heat sensitive element 82 from the device vertical direction (an example in one direction) (FIG. 6). 11). Specifically, when viewed from the width direction of the device, the proximity layer 384A is formed with a fan-shaped recess 386 so as to sandwich the heat sensitive element from the vertical direction of the device. A pair of fan-shaped gaps 390 are formed between the contact member 384 and the insulating film 96.

As described above, a pair of gaps 390 are formed between the contact member 384 and the insulating film 96 so as to sandwich the heat sensitive element 82 from the vertical direction (one direction) of the device. Therefore, in the lubricating oil absorbed from the end of the contact member 384, the lubricating oil S soaks into the heat-sensitive element 82 side and from the separating layer 384B side to the adjacent layer 384A side (see the arrow in FIG. 11). A part of the oil exudes from the contact member 384 and is captured in the gap 390. In other words, the path of the lubricating oil S that is absorbed by the contact member 384 and permeates into the heat sensitive element 82 side from the vertical direction of the device is blocked.

Therefore, when viewed from the width direction of the device, it is absorbed by the contact member 384 of the portion in contact with the heat sensitive element 82 as compared with the case where the contact member and the insulating film are in contact with each other on the entire circumference of the heat sensitive element 82. The amount of the lubricating oil S is reduced, and the decrease in the responsiveness of the temperature detection device 380 is suppressed.

The other actions of the third embodiment are the same as those of the second embodiment.

<Fourth Embodiment>
Next, an example of the temperature detection device, the fixing device, and the image forming device according to the fourth embodiment of the present invention will be described with reference to FIGS. 12 and 13. In addition, about 4th Embodiment, the part different from 2nd Embodiment will be mainly described.

As shown in FIG. 12, the heating unit 452 in the fixing device 450 of the image forming device 410 of the fourth embodiment includes a temperature detecting device 480. The temperature detection device 480 has a heat sensitive element 82, a contact member 484 that comes into contact with the heat sensitive element 82 and suppresses heat from being released from the heat sensitive element 82, and a support member 92. Further, the temperature detection device 480 includes a pair of electric wires 94 for applying a voltage to the heat sensitive element 82 and an insulating film 96.

The contact member 484 extends in the depth direction of the device, and the side in contact with the heat sensitive element 82 (side of the planar heating element 64) is formed in a semicircular shape when viewed from the depth direction of the device. The contact member 484 is formed of a plurality of (two in the present embodiment) layers laminated in the device width direction (contact direction), and is in close proximity to the thermal element 82 with the proximity layer 484A. It has a separation layer 484B that is separated from the heat sensitive element 82.

The proximity layer 484A and the separation layer 484B are silicone rubber sponges (silicon rubber foams) having voids inside. The porosity of the proximity layer 484A is lower than the porosity of the separation layer 484B. In other words, the water absorption of the proximity layer 484A is lower than that of the separation layer 484B.

Further, when viewed from the width direction of the device, a gap 490 is formed between the contact member 484 and the insulating film 96 so as to surround the heat sensitive element 82 (see FIG. 13). Specifically, a recess 486 is formed in a portion of the proximity layer 484A on the central side in the device depth direction. Then, on the bottom surface 486A of the recess 486, a support portion 488 that supports the heat sensitive element 82 extends in the device width direction from the central side portions in the device depth direction and the device vertical direction. As a result, a gap 490 is formed between the contact member 484 and the insulating film 96 when viewed from the width direction of the device so as to surround the heat sensitive element 82.

As described above, a gap 490 is formed between the contact member 484 and the insulating film 96 so as to surround the heat sensitive element 82. Therefore, a part of the lubricating oil S that is absorbed by the contact member 484 and permeates from the periphery of the heat sensitive element 82 to the heat sensitive element 82 side when viewed from the width direction of the device seeps out from the contact member 484 and is captured in the gap 490. NS. In other words, the path of the lubricating oil S that is absorbed by the contact member 484 and permeates from the periphery of the heat sensitive element 82 to the heat sensitive element 82 side when viewed from the width direction of the device is blocked.

Therefore, when viewed from the width direction of the device, the portion in contact with the heat sensitive element 82 is compared with the case where a gap is formed between the contact member and the insulating film so as to sandwich the heat sensitive element 82 from one direction. The amount of lubricating oil S absorbed by the contact member 484 of the above is reduced. As a result, the decrease in the responsiveness of the temperature detection device 480 is suppressed.

The other actions of the fourth embodiment are the same as those of the second embodiment.

Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. That is clear to those skilled in the art. For example, in the above embodiment, the porosity of the proximity portions 84A, the proximity layers 284A, 384A, and 484A is lower than the porosity of the separation portions 84B, the separation layers 284B, 384B, and 484B, so that the water absorption of the proximity portions is low. Was lower than the water absorption of the separated part, but a material with low water absorption (for example, a material with low hydrophilicity) was used for the adjacent part, and a material with high water absorption (for example, a material with high hydrophilicity) was used for the separated part. May be used.

Further, in the above embodiment, the contact members 84, 284, 384, and 484 are formed by the proximity portion 84A, the proximity layers 284A, 384A, and 484A, and the separation portion 84B, the separation layers 284B, 384B, and 484B. The member may have other parts (other layers) such as an intermediate part.

Further, in the above embodiment, the volume ratio between the proximity portion 84A and the proximity layers 284A, 384A and 484A and the separation portion 84B and the separation layers 284B, 384B and 484B is not particularly described, but 20:80 may be used. It may be 50:50 or 80:20. In this case, since the volume of the separated portion having high water absorption is increased, the amount of the lubricating oil S that comes into contact with the heat sensitive element 82 is reduced, and the decrease in the responsiveness of the heat sensitive element is suppressed.

Further, in the third embodiment, a pair of gaps 390 are formed between the contact member 384 and the insulating film 96 so as to sandwich the heat sensitive element 82 from the vertical direction (one direction) of the device, but the gap is 1 Only one may be used. In this case, the effect of forming a pair of gaps 390 does not work.

10 Image forming device 20 Image forming part 50 Fixing device 52 Pressurizing part (example of pressurizing member)
62 Endless belt (example of cylindrical member)
64 planar heating element (example of heating member)
80 Temperature detection device 82 Thermal element 84 Contact member 84A Proximity part 84B Separation part 86 Sheet member 92 Support member 94 Electric wire (example of conductive part)
96 Insulating film (an example of covering film)
210 Image forming device 250 Fixing device 280 Temperature detecting device 284 Contact member 284A Proximity layer 284B Separation layer 310 Image forming device 350 Fixing device 380 Temperature detection device 384 Contact member 384A Proximity layer 384B Separation layer 390 Gap 410 Image forming device 480 Temperature detection device 484 Contact member 484A Proximity layer 484B Separation layer 490 Gap

Claims (9)

With a thermal element
The contact member that is in contact with the heat-sensitive element, and the water absorption of the portion close to the heat-sensitive element is lower than the water absorption of the separated portion that is separated from the heat-sensitive element. With parts,
The contact member is formed of a plurality of sheet members stacked in a contact direction in contact with the heat sensitive element, and has a gap.
The number of laminated sheet members per unit thickness of the close portion is increased as compared with the number of laminated sheets per unit thickness of the separated portion, and the porosity of the close portion is compared with the porosity of the separated portion. And a low temperature detector. The contact member is formed of a plurality of sheet members stacked in a contact direction in contact with the heat sensitive element.
The temperature detection device according to claim 1 , wherein the mass per unit thickness of the adjacent portion is larger than the mass per unit thickness of the separated portion. The contact member is formed of a plurality of layers laminated in the contact direction in contact with the heat sensitive element.
The temperature detection device according to claim 1 , wherein the porosity of the proximity layer constituting the proximity portion is lower than the porosity of the separation layer constituting the separation portion. A support member that is arranged on the opposite side of the heat sensitive element with the contact member in between and supports the contact member is provided.
The temperature detection device according to claim 3 , wherein the support member supports the contact member in a non-contact state with the proximity layer. The heat-sensitive element and the covering film covering the contact member,
The temperature detecting device according to any one of claims 1 to 4 , further comprising a conductive portion arranged between the covering film and the contact member and for applying a voltage to the heat sensitive element. The thermal element and the covering film covering the contact member are provided.
The contact member is larger than the heat sensitive element when viewed from the contact direction in which the contact member is in contact with the heat sensitive element, and the contact member and the covering film are formed when viewed from the contact direction. The temperature detection device according to any one of claims 1 to 5 , wherein a gap is formed between the heat sensitive elements so as to sandwich the heat sensitive element from one direction. The temperature detection device according to claim 6 , wherein the gap is formed so as to surround the heat sensitive element when viewed from the contact direction. A cylindrical member that is cylindrical and has a liquid applied to its inner peripheral surface and orbits.
A heat-generating member that generates heat to heat a part of the inner peripheral surface of the cylindrical member,
The temperature detecting device according to any one of claims 1 to 7 , which detects the temperature of the heat generating member, and the temperature detecting device.
A pressure member that is arranged on the opposite side of the heat generating member with the cylindrical member in between and pressurizes a recording medium on which an image is transferred to the outer peripheral surface of the cylindrical member.
A fixing device equipped with. An image forming unit that forms an image on a recording medium,
The fixing device according to claim 8 for fixing the image on a recording medium,
An image forming apparatus comprising.

Images