JPH0561372A - Heater and fixing device - Google Patents

Abstract

PURPOSE:To prevent the camber of a heater based on a difference in thermal expansion between a good heat conductive substrate and an insulation holder and to improve the durability of an adhesive by sticking the good heat conductive substrate to a holder, on one end of one side, out of the heating region of a resistance heating element. CONSTITUTION:A heater unit is composed of a heating body 1 and the holder 2 insulating and supporting the heating body 1. The heating body 1 is composed of the good heat conductive substrate 3, the resistance heating element 4 provided on one surface side of the good heat conductive substrate 3, a temperature detecting element provided on the other surface side, and a protective layer protecting the resistance heating element. Then, the good heat conductive substrate 3 is adhered with an epoxy adhesive on an adhesive region. Moreover, as the adhesive, a silicone adhesive, or an adhesive tape made of acrylate resin, or an adhesive tape made of silicone resin, can be used, Thus, the adhesive region is, out of the heating region, which is a region heated by the resistance heating element, and especially, separated from the heating region by a distance (a).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate having good thermal conductivity, a heater having a resistance heating element provided on the substrate, and a fixing device using the heater.

2. Description of the Related Art Conventionally, as a heating type fixing device, an unfixed toner image is formed by a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer in pressure contact with the heating roller. A fixing device of a heat roller fixing system, which heats the recording material on which the recording material is formed while being nipped and conveyed, is often used.

In this heat roller fixing device, the entire peripheral surface of the heat roller must be maintained at a constant temperature accurately.

For this reason, the heating roller requires a large heat capacity, and a so-called warm-up time is required until the surface of the heating roller is raised to a predetermined fixing temperature.

Therefore, the applicant uses a heater in which a resistance heating element is provided on a substrate having good thermal conductivity such as alumina in JP-A-2-157878 and JP-A-2-253382, and the heat of the heater is used. A fixing device for heating and fixing an image on a recording material that is in close contact with the film is provided.

This fixing device has a small heat capacity, and since heat is concentratedly directed to the nip side, the warm-up time is short and power saving can be achieved.

[0007]

In order to concentrate heat in this manner, the good thermal conductive substrate is heat-insulated and supported by a holder made of a heat insulating material.

When fixing the good heat conductive substrate to the holder, if it is firmly adhered to the entire area or a large number of points in the longitudinal direction, the following problems occur.

This problem will be described with reference to FIGS.

The linear thermal expansion coefficient of the good thermal conductive substrate is different from that of the heat insulating holder.

For this reason, as shown in FIG. 5, when the good thermal conductive substrate 3 is bonded to the holder 2 with the adhesive C at five points, warping may occur as shown in FIG. is there.

When such a warp occurs, there is a possibility that the fixing film may be bent in a convex shape toward the central portion to cause defective fixing.

Therefore, the applicant first filed there in Japanese Patent Application No. 2-17.
In No. 9096, it was proposed to adhere at one place in the longitudinal direction.

However, the substrate and the holder are heated to a high temperature of 170.degree.

For this reason, it is difficult to reliably fix the good thermal conductive substrate to the holder for a long period of time because the adhesive is deteriorated by heat even if it is bonded at only one place in the longitudinal direction.

[0016]

The present invention for solving the above-mentioned problems provides a heater having a good thermal conductive substrate having a linear resistance heating element and a holder for thermally insulating and supporting the substrate, wherein the substrate is Characterized by being bonded to the holder outside the heat generating area of the resistance heating element in the longitudinal direction,
In particular, the above-mentioned substrate is characterized in that it is bonded to a holder at one end on one side, and a good thermal conductive substrate and a resistor provided linearly along the longitudinal direction of the good thermal conductive substrate. In a fixing device that has a heating element and a holder that heat-insulates a good thermal conductive substrate, and that heats and fixes an image on a recording material by heat from the resistance heating element, the substrate is the longitudinal direction of the resistance heating element. It is characterized in that it is adhered to the holder outside the heat generating region, and in particular, the base is adhered to the holder at one end on one side.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

1, 2 and 3 are views showing a heater unit of an embodiment of the present invention, FIG. 1 is a front view, FIG. 2 is an enlarged view and FIG. 3 is a sectional view taken along line AA.

The heater unit comprises a heating element 1 and a holder 2 for supporting the heating element 1 in a heat insulating manner.

The holder 2 for heat-insulating and supporting the heating element 1 has high heat resistance and rigidity. For example, PPS (polyphenylene sulfide) / PAI (polyamide imide) /
It can be made of high heat resistant resin such as PI (polyimide), PEEK (polyether ether ketone), liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass or the like.

The heating element 1 includes a good thermal conductive substrate 3, a resistance heating element 4 provided on one side of the good thermal conductive substrate 3, and a temperature measuring element 5 (FIG. 4) provided on the other side. It comprises a protective layer 6 (FIG. 4) for protecting the resistance heating element.

The good heat conductive substrate 3 is a member having heat resistance, insulation and low heat capacity, and as an example, thickness 1.0 mm, width 1
It is an alumina substrate having a length of 6 mm and a length of 340 mm.

The heating element 4 is provided along the length of the lower surface of the substrate 3 (on the side facing the film 7), for example, Ag / P.
An electric resistance material such as d (silver-palladium) or Ta ₂ N is applied by screen printing or the like to a thickness of about 10 μm and a width of 1 to 3 mm, and a heat-resistant glass as a surface protective layer is applied on the surface of about 10 μm.
It is m-coated.

As an example, the temperature measuring element 5 has a low heat capacity such as a Pt film provided by coating by screen printing or the like on substantially the central portion of the upper surface of the substrate 3 (the surface opposite to the surface on which the heating element 4 is provided). Is a resistance temperature detector. Alternatively, as the temperature detecting element, a thermistor having a low heat capacity may be arranged in contact with the substrate 3.

The good thermal conductive substrate 3 is bonded to the holder 2 in the bonding area shown in FIG. The adhesive is an epoxy adhesive. Alternatively, a silicone adhesive, an acrylic resin adhesive tape, or a silicone resin adhesive tape may be used.

As described above, the bonding area is provided outside the heating area, which is the heating area of the resistance heating element, particularly at a distance a from the heating area.

By bonding in such a low temperature region, the durability of the adhesive can be improved.

The distance a is preferably 1 to 5 mm. 10
Reference numeral 4 denotes an electrode terminal, which is connected to the contact plate 103. The contact plate 103 is screwed onto the holder 2, and one end of the contact plate 103 is soldered to the heater electrode portion 4a. Therefore, when the good thermal conductive substrate and the holder 2 move relative to each other, the contact plate 103 or the solder 105 is moved.
At, destruction occurs.

Therefore, by fixing the good thermal conductive substrate and the holder in the bonding area, the breakage can be prevented.

The other end side is free in the longitudinal direction, and the difference in thermal expansion between the good thermal conductive substrate and the holder can be allowed.

As the electrode, a clip type electrode 108 is used as shown in FIG. 7 so as to obtain a degree of freedom in the longitudinal direction.

FIG. 4 shows a sectional view of a fixing device using the above-mentioned heater.

Reference numeral 7 denotes an endless belt-shaped fixing film, which includes a left driving roller 8, a right driven roller 9 and
A low heat capacity linear heating element 1 as a heating element arranged below the rollers 8 and 9 along a direction intersecting the moving direction of the film 7 is suspended between the three members 8 and 9 and 1. It is set up.

The driven roller 9 also serves as a tension roller for the endless belt-shaped fixing film 7, and the fixing film 7 is rotated at a predetermined peripheral speed in the clockwise direction in accordance with the clockwise rotation of the driving roller 8, that is, image formation. The unfixed toner image Ta conveyed from the sheet side is rotationally driven at the same peripheral speed as the conveying speed of the recording material P carrying the upper surface without wrinkles, meandering, or speed delay.

Reference numeral 10 is a pressure roller as a pressure member having a rubber elastic layer 12 having a good releasability such as silicon rubber, and sandwiching the lower film portion of the endless belt-shaped fixing film 7 therebetween. The lower surface of the heating body 1 is opposedly pressed against the lower surface of the heating body 1 by a biasing means (not shown) with a contact pressure of, for example, 4 to 7 kg, and the shaft 11 is centered in the counterclockwise direction in the forward direction of the conveyance direction of the recording material P. Rotate to.

In the case of the heating element 1 of this example, the linear or strip-shaped branch heating element 4 is selected from both longitudinal ends of the branch heating element 4 in accordance with the recording material size and is energized. The heating area of the heating element 4 can be changed according to the paper size.

The energizing method according to the size of the recording material is described in detail in JP-A-3-144477.

The energization is AC 100 V, and the energization power is controlled by controlling the energizing phase angle by an energization control circuit (not shown) including a triac according to the detected temperature of the temperature detecting element 5.

The fixing film 7 has heat resistance, releasability, durability and the like, and generally has a total thickness of 100 μm or less, preferably 40.
A single-layer or multi-layer film having a thickness of μm or less can be used.

Next, the operation of this fixing device will be described.

A recording material sheet P having an unfixed toner image Ta on its upper surface, which is conveyed to the fixing device 60 by an image forming device (not shown) which uses this fixing device in response to an image formation start signal It is guided by the guide 18 and enters between the fixing film 7 and the pressure roller 10 at the pressure contact portion (fixing nip portion) between the heating body 1 and the pressure roller 10 and the unfixed toner image surface of the sheet P is formed. The heating element 1 and the pressure roller 10 are in close contact with the lower surface of the fixing film 7 which is rotated at the same speed as the conveying speed and in the same direction without causing surface misalignment, wrinkling or deviation, and the heating body 1 and the pressure roller 10 in an overlapping state with the fixing film 7. Passing through the mutual pressure contact parts while receiving the clamping pressure.

Since the heating element 1 is electrically heated at a predetermined timing by the image formation start signal, the toner image Ta is generated.
Is heated at the press contact portion and becomes a softened / melted image Tb.

At the edge portion S (having a radius of curvature of about 2 mm) of the heater support 2 having a large curvature, the running direction of the fixing film is turned at a steep angle (the bending angle θ is about 45 °).
Therefore, the sheet P conveyed through the pressure contact portion while being overlapped with the fixing film 7 is curvature-separated from the fixing film 7 at the edge portion S, and is ejected to the ejection tray. By the time the paper is ejected, the toner is sufficiently cooled and solidified and is in a state of being completely fixed on the sheet P (toner image Tc).

Further, in this example, the heat capacity of the heating element 4 and the substrate 3 of the heating element 1 is small, and these are the support 2
Since it is adiabatically supported by, the surface temperature of the heating element 1 at the pressure contact portion rises to a sufficiently high temperature with respect to the melting point of the toner (or the temperature at which the toner P can be fixed) in a short time.
It is not necessary to raise the temperature of the heating element 1 in advance (so-called standby temperature adjustment), energy can be saved, and the temperature rise inside the machine can be prevented.

[0045]

As described above, according to the present invention, the heater does not warp or bend even if thermal expansion occurs due to heat generation by energization.

Also, the durability of the adhesive can be improved.

[Brief description of drawings]

FIG. 1 is a front view of a heater according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of the heater shown in FIG.

3 is a sectional view of the heater shown in FIG.

FIG. 4 is a cross-sectional view of the fixing device according to the exemplary embodiment of the present invention.

FIG. 5 is a plan view for explaining a problem solved by the present invention.

FIG. 6 is a cross-sectional view for explaining a problem solved by the present invention.

FIG. 7 is a partially enlarged cross-sectional view of the heater shown in FIG.

[Explanation of symbols]

 1 heating element 2 holder 3 good thermal conductive substrate 4 resistance heating element

Claims (7)

[Claims] 1. A heater having a good thermal conductive substrate having a linear resistance heating element and a holder for heat-insulating and supporting the substrate, wherein the substrate is outside the heating region of the resistance heating element in the longitudinal direction. A heater characterized by being adhered to. 2. The heater according to claim 1, wherein the base is adhered to the holder at one end on one side. 3. The heater according to claim 1, wherein the heater has an electrode for energizing a resistance heating element, and the base is bonded to the holder at a position facing the electrode.
Heater. 4. A good thermal conductive substrate, a resistance heating element linearly provided along the longitudinal direction of the good thermal conductive substrate, and a holder for heat-insulating and supporting the good thermal conductive substrate. A fixing device for heating and fixing an image on a recording material with heat from a resistance heating element, wherein the base is bonded to the holder outside the heating area of the resistance heating element in the longitudinal direction. 5. The fixing device according to claim 4, wherein the base is adhered to the holder at one end on one side. 6. An electrode for energizing the resistance heating element,
6. The fixing device according to claim 4, wherein the base is bonded to the holder at a position facing the electrode. 7. The fixing device according to claim 4, wherein the device further comprises a moving film in close contact with the recording material, and the image on the recording material is heated through the film. ..