JP3027070B2 - Heating body manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heating element for heating a paper sheet, and more particularly to a heating element for use in a fixing device for permanently fixing a toner image in electrophotography to the paper sheet.
It relates to the law.

[0002]

2. Description of the Related Art Conventionally, a heat roller method has been proposed as a method for heating a sheet.

[0003] However, in this method, a high temperature must be maintained at all times, and the energy consumption for the method is large, which is against energy saving. In addition, even during standby, heat is released into the machine, causing a problem of temperature rise. Also, it took time to heat the roller to a temperature suitable for heating the paper leaf.

Japanese Patent Laid-Open Publication No. Sho 63-163 discloses a method in which a heating element is formed by providing a pattern of a resistance heating element on a ceramic substrate and heating the sheet to heat the sheet through a thin film.
No. 3,131,182.

FIG. 2 shows an example of such a film heating apparatus.
Shown in

The heating device shown in FIG. 2 is arranged with a thin heat-resistant film 2 (or sheet), a driving roller 12 for the film 2 and one side of the film 2 fixedly supported. A heating element 3 having a constant temperature, and a visible image bearing surface of a recording material P which is disposed on the other side of the heating element 3 so as to face the heating element 3 and on which an image is to be fixed with the heating element 3 via the film 2. And a pressure roller 6 for adhering the film 2
Is a recording material P to be image-fixed which is conveyed and introduced between the film 2 and the pressure roller 6 at least at the time of image fixing.
The recording material is moved in the forward direction at substantially the same speed, and passes through a nip portion as a fixing portion formed by pressing the heating member 3 and the pressure roller 6 with the traveling moving film 2 interposed therebetween. Is heated by the heating element 3 through the fixing film 2 to apply heat energy to the developed image (unfixed toner image) to soften / melt it. The basic configuration is to separate the recording material P at the separation point.

Reference numeral 13 denotes a tension roller for applying tension to the film 2.

In such a film heating method, a heating element having a very small heat capacity and a rapid temperature rise can be used, and the time required for the heating element to reach a predetermined heating temperature can be greatly reduced.

The temperature of the heating element 3 is controlled by energizing the heating element 4 so that the temperature of the heating element 3 detected by the temperature detecting element 10 becomes constant.

[0010] The temperature detecting element 10 is always disposed at a position corresponding to a paper passing area so that the temperature of the paper passing section is constant regardless of the paper size of the paper passing.

In this method, the temperature of the heating element rises in a short time, so that even if the sheet is immediately passed, the heating element is heated to a temperature required until the sheet reaches the fixing portion. be able to. In addition, no heating is performed during standby, so there is no temperature rise inside the machine and no energy is consumed.

In this type of heating element, the resistance distribution is made uniform at the ends, or the resistance distribution is made higher at the ends so as to compensate for the escape of heat at the ends.

On the other hand, in a fixing-type heating device that drives a film without tension, a heating element is attached to a plastic stay, which is a heating element holding member, so that heat escapes in the rear direction of the heating element is small. Since there is no absorption and equalization of heat from the film by rollers etc., unevenness of the resistance distribution of the heating element appears as a temperature distribution on the paper sheet as it is, and it appears as fixing unevenness, gloss unevenness, offset Had become.

On the other hand, a ceramic heater used in such a heating device is manufactured as follows.

FIG. 3 shows an outline of the manufacturing process. Reference numeral 15 denotes a support for holding a ceramic base, and 14 denotes a ceramic base. The ceramic base 14 is prevented from being displaced by, for example, being attracted to the support base 15 from the back by vacuum. Reference numeral 16 denotes a screen for printing, which is coarse in only a portion indicated by reference numeral 18, and the resistor paste can pass through only this portion. Reference numeral 17 denotes a frame for applying tension to the screen. Reference numeral 19 denotes a squeezer for spreading the paste on the screen and attaching the paste to the ceramic base material at a constant thickness from the eyes of the screen.

Reference numeral 20 denotes a dispenser for supplying a fixed amount of paste before the squeezer 19 moves. The dispenser 20 is supplied with a paste from a tank (not shown).

FIG. 4 shows a state in which the screen 16 is superimposed on the ceramic base material. After the paste is supplied by the dispenser 20 in front of the squeezer 19, the squeezer moves in the direction of arrow S, and The paste is pressed into the rough part 18.

Thereafter, the screen is removed, and the printed ceramic base material is subjected to drying and firing steps to complete the formation of the resistance heating element. Thereafter, glass coating is performed by the same screen printing.

[0019]

However, in such a tensionless film heating apparatus, when a conventional ceramic heating element is used as a heating source, defective fixing, offset, gloss unevenness, and the like may occur.

In particular, when the heating resistor of the heating element is formed by a screen printing method, the thickness of the resistor varies in the moving direction of the drawer, so that the resistance distribution is inclined in the longitudinal direction of the heater (not constant). ).

[0021]

That to solve the above problems, according to means for solving the problems]
The method of manufacturing the heating element is to paste a resistive material for printing.
Squeeze along the band pattern formed on the screen
While applying it on the insulating substrate, drying and firing
In the manufacturing method of the heating element forming the belt-shaped resistance heating element
The width of the band pattern on the screen is in the squeeze direction.
It is characterized by a continuous narrowing from the stream to the downstream
And In addition, another method for manufacturing a heating element is a paste-like method.
Band-shaped putter formed on a screen for printing resistive material
While squeezing along the
A heating element that forms a belt-shaped resistance heating element through a drying and firing process
In the method for manufacturing, the band-shaped pattern surface of the screen
Continuously tilts downward from upstream to downstream in the squeeze direction.
Is characterized by

[0022]

FIG. 1 shows a heater obtained by carrying out the present invention.
FIG. 3 is a schematic sectional view of a tensionless film heating type fixing device showing an example of a fixing device that can be effectively implemented .

[0023] In FIG. 1, 1 is a horizontally long stay made of resin, the inner surface guide member to be described later film 2.
Reference numeral 2 denotes an endless heat-resistant film, which is fitted around the stay 1 including the heating element 3. The inner peripheral length of the endless heat-resistant film 2 and the outer peripheral length of the stay 1 including the heater 3 are larger than that of the stay 2 including the heater 3 by, for example, about 3 mm. The circumference is loosely fitted with a margin. In order to improve the quick start property by reducing the heat capacity of the film 2, the total thickness of the film 2 is about 100 μm or less, and PTFE, PF having heat resistance, mold release property, strength, durability and the like.
A, FEP single layer, or PT on the outer surface of polyimide, polyamide imide, PEEK, PES, PPS, etc.
A composite layer film coated with FE, PFA, FEP or the like can be used.

In this embodiment, P is applied to the outer peripheral surface of the polyimide.
A TFE-coated one having a total thickness of 50 μm was used.

Reference numeral 3 denotes a heating element. A heating element 4 is made of an electric resistance material such as Ag / Pd (silver palladium) about 10 μm thick and has a width of 1 to 3 along a substantially central portion of a substrate made of alumina or the like.
The protective layer 5 is coated with glass, fluororesin, or the like as a protective layer 5.
A heating element temperature detecting element 10 is provided on the surface of the heating element 3 opposite to the fixing film, and the temperature of the heating element 3 is controlled by the CPU 11 based on the temperature detected by the temperature detecting element. The position of the thermistor is set in the vicinity of the conveyance reference portion in order to secure stable fixing properties, and the temperature of the passage portion of the recording material P carrying the toner image T is always controlled.

Reference numeral 6 denotes a pressure roller as a rotating member for forming a fixing nip portion with the film 2 sandwiched between the heating member 3 and the film, and a stainless shaft 7 having an outer diameter of 8 mm and a length of 220 mm. Fluorine latex coat (GLS manufactured by Daikin Co., Ltd.)
213 mixed with 10% by weight of FEP)
A roller section 8 having a hardness of 50 ° (Asker C hardness) coated and fired, and a stainless steel shaft 7
Is driven from the end by the driving means (not shown). With such a configuration, a load of about 50N is applied between the pressure roller 6 and the stay 1, so that heat is sufficiently transmitted to the sheet via the film. As a result, a nip width of 2 to 3 mm is formed from the center to both ends in the paper passing direction. In this state, the temperature distribution of the paper sheet was measured using an infrared thermometer (ThermoPure, manufactured by JEOL Ltd.). Was found to occur.

In particular, when the temperature distribution of the heating element was measured as a single product, a portion having a temperature difference of 20 degrees or less with respect to the contact portion of the temperature detecting element for detecting the temperature resulted in poor fixing, and conversely the temperature difference was 20 degrees or more. Was offset in the part.

The cause of the temperature difference is a variation in the distribution of the resistance pattern of the heating element. According to the experiment, when the resistance value of the temperature detecting element portion is 100%, a difference of 1% in resistance value appears as a temperature difference of 2 degrees with respect to the control temperature when the heating element is heated. Was.

Therefore, in order to realize a temperature distribution on the paper sheet that does not cause fixing failure and does not cause offset, a unit length (10 mm) is required as a heating resistance distribution of the heating element.
When the resistance value per unit is measured and the resistance value of the temperature detecting element portion is set to 100%, the difference from the resistance value of each portion is ±
It may be within 10%.

In the case where the A4 size sheet can be fed vertically in the above-described configuration, when the length of the heating resistor of the heating element is set to 230 mm and the total resistance is set to 28.3Ω, the temperature detecting element is used. Was adhered at a position 10 mm from the end of the sheet, and the resistance per unit length of the heating element at the temperature detecting element was 1.23 Ω / 10 mm. On the other hand, when the resistance value obtained by dividing the heating resistance length 230 mm into 23 equal parts was measured, it was 1.35 to 1.11 Ω / 10 mm.
In this case, the temperature distribution on the paper sheet certainly falls to 20 degrees or less in the range, and also falls within 10 degrees or less with respect to the temperature detecting element portion. As a result, no fixing failure and no offset occur. . In addition, improvement in gloss unevenness was observed.

In the above-described embodiment, the distribution of the heating resistance is ± 10% with respect to the temperature sensing element portion over the entire length of the heating element.
% Variation.

However, in view of the width of the nip actually formed by the pressure roller and the stay, the nip tends to be large at both ends, so that heat is easily transmitted to the paper sheet. Therefore, in a system in which the nip is widened toward both ends by using a plastic stay as described above, it is possible to uniformly supply heat to the paper sheet by setting the temperature of the heating body at both ends lower than that at the center.

Normally, the nip width is 0.1 mm at both ends with respect to the center.
The width is increased by 5 to 1.0 mm. In this situation, in order to realize a temperature distribution on the paper sheet that does not cause fixing failure and does not cause offset, a resistance value per unit length (10 mm) is measured as a heating resistance distribution of the heating element. To
Assuming that the resistance value of the temperature sensing element portion is 100%, the resistance value of the central portion is within ± 10% of this, and both ends are 40 m.
m may be within the range of -15% to + 5%.

In a case where the A4 size sheet is configured to be fed vertically in the above-described configuration, when the length of the heating resistor of the heating element is set to 230 mm and the total resistance is set to 28.3Ω, the temperature detecting element is used. Was adhered at a position 10 mm from the end of the paper sheet, and the resistance per unit length of the heating element at the temperature detecting element was 1.23 Ω / 10 mm. On the other hand, when the resistance value obtained by dividing the heating resistance length 230 mm into 23 equal parts was measured, it was 1.35 to 1.11 Ω / at the center.
10 mm, 1.05 to 1.
When it is set to 29 Ω / 10 mm, the temperature distribution on the paper sheet is further improved to be 10 degrees or less in the range, and the temperature detection element portion also falls within a difference of 5 degrees or less. Offset no longer occurs. Further, gloss unevenness could not be completely eliminated in the above embodiment, but was solved in this embodiment.

FIG. 3 shows an outline of the manufacturing process. Reference numeral 15 denotes a support for holding a ceramic base, and 14 denotes a ceramic base. The ceramic base is prevented from being displaced by, for example, being attracted to the support table from the back by vacuum.
Reference numeral 16 denotes a screen for printing, which is coarse at only a portion 18 and through which only the resistor paste of the resistor can pass. Reference numeral 17 denotes a frame for applying tension to the screen. Reference numeral 19 denotes a squeezer for spreading the resistor paste on the screen and attaching the paste to the ceramic base material with a constant thickness from the eyes of the screen. 2
Reference numeral 0 denotes a dispenser for supplying a fixed amount of resistor paste before the moving direction of the squeezer 19.

As shown in FIG. 4, the screen 16 is placed on a ceramic substrate, and a resistor paste is supplied by a dispenser before the moving direction of the squeezing device 19, and the squeezing device is moved to move the ceramic paste through the opening of the screen. A resistor paste is applied to the substrate.

Conventionally, with such a configuration, the opening of the screen has the same width in the moving direction of the diaphragm 19. For this reason, since there is a large amount of resistor paste upstream in the moving direction, pressure is applied at the time of drawing, and the thickness of the printed paste becomes thin. On the other hand, on the downstream side, the paste was consumed, the pressure was reduced, and the paste was thickly applied.

In this embodiment, as shown in FIG. 5, by changing the shape of the opening of the screen between the upstream side and the downstream side, the resistance distribution of the completed heater can be made more uniform upstream and downstream. Was.

(Example 1) When printing a resistor having a width of 1.5 mm and a total length of 230 mm, the viscosity of the resistor paste was 150 kcps at room temperature.
When the width of the opening of the printing screen was narrowed by% on the upstream and downstream sides in the moving direction of the squeezing device, the slope of the resistance distribution of the finished product became 2% or less. What
In addition, as shown in FIG.
And B, as is clear from the figure, A> B
Thus, the pattern width is continuously narrowed.

COMPARATIVE EXAMPLE Resistor Width 1.5 mm Total Length 23
When printing with a resistor paste having a viscosity of 150 kcps at room temperature, the width of the opening of the printing screen was made equal between upstream and downstream in the moving direction of the squeezing device.

As a result, the downstream side is -6% lower than the upstream side.
As described above, the resistance distribution was low, and fixing failure occurred. As described above, the improvement can be achieved by making the width of the opening of the screen inclined with respect to the moving direction of the aperture stop.

[0042]

(Embodiment 2) In the above embodiment, the width of the opening of the screen is inclined.
Te has been improved resistance distribution, as shown in FIG. 6, may be changed how attached with respect to the frame 17 of the screen 16. Thus, the screen is stuck high (height h1) on the upstream side ,
Paste low (height h2) on the downstream side, that is, clear from FIG.
By continuously tilting the pattern surface downward like a kana ,
The pressure applied to the resistor paste is reduced to increase the printed thickness of the resistor paste.

Even with the above-described method, it is possible to supply a ceramic heating element which does not cause a fixing failure, an offset or the like by making the heat generation resistance distribution of the resistor uniform.

[0045]

As described above , according to the present invention ,
The heat generation distribution of the resistor can be made uniform,
A heating element without offset can be provided.

[0046]

[Brief description of the drawings]

FIG. 1 shows an effective implementation of a heater obtained by implementing the present invention.
Shown to cross-sectional view of an embodiment of a fixing device capable.

FIG. 2 is a cross-sectional view of a conventional tension type film fixing device.

FIG. 3 is an exploded perspective view showing a printing process of a heating resistor in the ceramic heating element.

FIG. 4 is a perspective view showing a printing process of a heating resistor in the ceramic heating element.

FIG. 5 is a plan view of an opening of a screen showing one embodiment of a method for manufacturing a heating body according to the present invention.

FIG. 6 is a schematic side view of a screen showing another embodiment of the method for manufacturing a heating body according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stay 2 ... Fixing film 3 ... Heating body 4 ... Heating resistor 5 ... Glass protective layer 6 ... Pressure roller 10 ... Temperature detection element 11 ... CPU 12 ... Drive roller 13 ... Tension roller 14 ... Ceramic base material 16 ... Screen 17 ... Frame 18 ... Opening 19 ... Drawer 20 ... Dispenser

Continuation of the front page (72) Inventor Atsuyoshi Abe 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Manabu Takano 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Ryo Hayakawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Koichi Okuda 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. (56) Reference Document JP-A-2-157788 (JP, A) JP-A-4-115947 (JP, A) JP-A-4-31049 (JP, A) JP-A-3-163779 (JP, A) JP-A-4- 237084 (JP, A) JP-A-5-266972 (JP, A) JP-A-5-190260 (JP, A) JP-A-2-129883 (JP, A) JP-A-2-65086 (JP, A) 63-835 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/20 H05B 3/00-3/86 B41M 15/00-15/46

Claims (2)

(57) [Claims] 1. A paste-like resistive material is coated on an insulating substrate while squeezing along a belt-like pattern formed on a printing screen, and then dried and fired to form a belt-like resistive heating element. In the method for manufacturing a heating body, the width of the band-shaped pattern of the screen may be upstream of a squeezing direction.
A method for producing a heating element, wherein the heating element is continuously narrowed from downstream to downstream . 2. A printing screw for a paste-like resistive material.
While squeezing along the belt-shaped pattern
Coated on an insulating substrate, dried and fired to form a strip
In the method for manufacturing a heating element for forming a resistance heating element, the band-shaped pattern surface of the screen may be upstream of a squeezing direction.
A method for producing a heating element, wherein the heating element is continuously inclined downward from downstream to downstream .