JP3284580B2 - heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater in which an electric heating resistor is provided on the surface of an electrically insulating substrate, and heat is generated by energizing the resistor.

[0002]

2. Description of the Related Art As a device utilizing such a heater, there is a heating device of a film heating system.

[0003] The heating device is known from Japanese Patent Application Laid-Open No. 63-313182 and the like proposed by the applicant of the present invention, and includes an image heating and fixing device in an image forming apparatus such as an electrophotographic copying machine, a printer and a facsimile. That is, a recording material (electro-fax sheet, electrostatic recording sheet, transfer material sheet) is formed by using a toner (developing agent) made of a heat-meltable resin or the like by an image forming process means such as electrophotography, electrostatic recording, or magnetic recording. An image in which an unfixed toner image corresponding to the target image information, which is formed on a surface of a printing paper or the like by a direct method or an indirect (transfer) method, is heat-fixed as a fixed image on a recording material carrying the image; It can be used as a heat fixing device.

Further, for example, it can be used as a device for heating a recording material carrying an image to improve the surface properties such as luster, or a device for performing a temporary deposition process.

FIG. 20 shows a schematic configuration (a schematic cross-sectional view) of a main part of the heating apparatus. 21 and 22 are a partially cutaway plan view and a rear view of the heater.

[0006] 1 is a heater (heating body), a. An elongated substrate 2 having electrical insulation, heat resistance and low heat capacity; b. A heat-generating resistor 3 formed in a linear narrow band along the longitudinal direction of the substrate 2 at a central portion in the substrate width direction on one surface side (front surface side) of the substrate 2; c. Electrode terminals (connection terminals) 4.5 formed on the substrate surface by conducting to both ends of the current-carrying resistor 3, respectively; d. An electrically insulative overcoat layer 6 of glass or the like as a heater surface protection layer covering the surface of the substrate 2 on which the current-generating resistor is formed; e. It comprises a temperature detecting element 7 such as a thermistor provided on the other side (back side) of the substrate 2.

The substrate 2 has, for example, a width of 10 mm and a thickness of 1 m.
It is a ceramic plate made of Al ₂ O ₃ , AlN, SiC or the like having a length of m and a length of 240 mm.

The heating resistor 3 has a thickness of, for example, 10 μm.
Ag / P coated by screen printing etc.
d (silver-palladium alloy), RuO ₂ , Ta ₂ N, etc.

In the cross section of the heater 1 for controlling and controlling the temperature of the fixing surface, the heater 1 is connected to a heating nip 3 (fixing nip N, which is described later) as shown in FIG.
The pressure portion is located at a substantially central portion in the width region.

The overcoat layer 6 side of the heater 1 is a film contact sliding surface side, and this surface side is exposed to the outside, and the heater 1 is fixedly supported on a heater supporting portion 9 via a heat insulating heater holder 8. .

Reference numeral 10 denotes an endless belt-like or long web-like heat-resistant film made of polyimide or the like having a thickness of, for example, about 40 μm. Reference numeral 11 denotes a rotary pressure roller as a pressure member for pressing the film against the heater 1. It is.

The film 10 is rotated or rotated while sliding on the heater 1 surface while being in close contact with the heater 1 surface in a direction indicated by an arrow at a predetermined speed by a driving member (not shown) or the rotational force of the pressure roller 11. Travel and move.

The heater 1 is applied with a voltage from an AC power supply 12 between the electrode terminals 4 and 5 at both ends of the current-generating resistor 3, and the temperature of the heater 1 rises as the current-generating resistor 3 generates heat.

The temperature of the heater 1 is detected by a temperature detecting element 7 on the back of the substrate, and the detected information is fed back to an energization control circuit 13 so that an AC power supply 12 supplies an electric heating resistor 3
By controlling the power supply to the heater 1, the temperature of the heater 1 is controlled to a predetermined temperature.

The temperature detecting element 7 of the heater 1 has a fixing surface having the best thermal responsiveness, that is, a portion on the back side of the substrate corresponding to the formation position of the energizing resistor 3 on the heater substrate surface side (just below the energizing resistor 3). (Corresponding to the position on the back side of the substrate).

The heater 1 is heated to a predetermined temperature by energizing the energizing heating resistor 3 of the heater 1.
Oite 0 was moved driven state, pressure-contact portion between the film 10 and the pressure roller 11 (pressure portion) a fixing nip N
The recording material P as a material to be heated is introduced with the unfixed toner image surface facing the film 10 side, so that the recording material P adheres to the film 10 surface and moves and passes through the fixing nip portion N together with the film 10. In the moving passage process, heat energy is applied to the recording material P from the heater 1 via the film 10, and the unfixed toner image t on the recording material P is heated and melted and fixed.

Conventionally, a heat roller system has been generally used as an image heating and fixing device. It consists of a fixing roller having a heater inside a metal roller and a pressure roller having elasticity. The recording material is introduced and passed through a fixing nip between the pair of rollers to heat and heat the toner image. Fix by applying pressure.

However, in such a heat roller type image heating and fixing apparatus, since the heat capacity of the roller is large, it takes time (rise time, warm-up time, and wait time) for the roller to reach a predetermined fixing temperature. For quick use, the temperature must be controlled to a certain temperature even when the machine is not in use. The same applies to other heating type fixing devices such as a hot plate type and an oven fixing type.

[0019] In contrast, in the apparatus of the film heating type, such as described above, the low thermal capacity heater as a heater 1
The use of a heater makes it possible to reduce the wait time (quick start property) compared to the conventional heat roller system, etc., and also allows quick start, so that preheating is not required when not in use. However, it is also possible to save power in a comprehensive sense. In addition, it has advantages such as solving various drawbacks of other system devices, and is effective.

With respect to the temperature control of the heater 1, the load resistance value of the current-generating resistor 3 is constant, and in order to control the heater 1 to a predetermined temperature, the voltage or current applied to the current-generating resistor 3 must be controlled. Controlling or controlling the energization time is adopted.

However, the method of controlling the voltage or current applied to the current-carrying heating resistor 3 complicates the peripheral circuit, and involves a relatively large power consumption in circuit parts other than the heater.

Therefore, a method of controlling the energizing time is generally adopted. The following two control methods have been mainly used.

[0023] As shown in the current waveform diagram in FIG.
Zero-cross wave number control to control whether to energize or de-energize for each half-wave of the power supply waveform.

[0024] As shown in the current waveform diagram in FIG.
Phase control that controls the phase angle that is applied for each half-wave of the power supply waveform.

However, these controls also have the following problems.

That is, in the zero-cross wave number control method,
The amount of power that can be supplied to control the temperature of the heater 1 to a predetermined value is binary in ON / OFF units in half-wave units of the power supply. Therefore, to accurately control the temperature,
A plurality of half waves are set as one block, and an ON / OFF pattern is set.
Control such as setting the duty of the FF is performed. Such control in units of blocks has a problem that the response time increases and the temperature ripple of the heater increases. On the other hand, when ON / OFF is switched for each half wave, there is a problem that a harmonic noise component is generated in the load current.

In the phase control method, the energization phase angle is 90
In the vicinity of °, a large level of switching noise occurs because the current starts to flow rapidly. In addition, there is a problem that a harmonic noise component is generated in the load current as in the zero-cross wave number control.

In order to improve the temperature control characteristics of the heater 1 and to reduce the noise at the power supply terminal, the heater is formed of a plurality of heating resistors on a substrate. A heating device and a temperature control device for selectively controlling energization of a heating resistor have been proposed (Japanese Patent Application No. 3-344530).

FIG. 25 is a cross-sectional model view of an example of such a heater having a plurality of energized heating resistors, FIG. 26 is a partially cutaway plan view, and FIG. 27 is a rear view.

The heater 1 of this embodiment has two heating resistors 3a and 3b having different resistance values on the surface of a substrate 2 in parallel at the center in the substrate width direction along the length of the substrate. .

The two parallel energizing heating resistors 3a and 3b
On one end side is a common electrode terminal 4 for both 3a and 3b.
Are formed on the surface of the substrate 2, and independent electrode terminals 5a and 5b are formed on the other surface of the substrate 2 on the other end side.

Reference numeral 7 denotes wiring for connecting the temperature detecting element 7 such as a thermistor disposed on the back surface of the substrate 2.

The energization of the two energized heating resistors 3a and 3b is controlled by an energization control circuit every half cycle of the AC power supply so that the temperature detected by the temperature detecting element 7 becomes a predetermined temperature. Out of the current-carrying heating resistors 3a and 3b, a. Both are energized b. Only one of them is energized c. Energize only the other side d. In both cases, the heater 1 is temperature-controlled by appropriately selecting and controlling four types of energization patterns that are not energized. Specifically, the following control method (1) or (2) is adopted.

(1) The temperature of the heater 1 is detected, compared with and calculated with reference temperature data to control the temperature within a predetermined set temperature range, and a plurality of switching circuits for controlling the energization to each of the resistors 3a and 3b. A method having an element and controlling energization of the resistors 3a and 3b for each half-wave of the power supply waveform based on the calculated control amount.

(2) The temperature of the heater 1 is detected, compared with and calculated with reference temperature data to control the temperature within a predetermined set temperature range, and a plurality of switching circuits for controlling energization to each of the resistors 3a and 3b. An Xerox detecting means for the power supply waveform, and energizing the resistors 3a and 3b based on the calculated control amount, and arbitrarily selecting a half-wave of the power supply waveform based on the output of the Xerox detecting means. How to control the phase.

According to any one of the above methods (1) and (2), a heater having extremely low switching noise of the power supply line and having extremely high temperature controllability can be obtained.

FIG. 28 is a partially cutaway plan view of a heater provided with three parallel heating elements 3a, 3c and 3b having different resistance values from each other. The energization control for these three energized heating resistors 3a, 3c, 3b is the same as in the above-described example.

(A) In the image heating and fixing apparatus as shown in FIG. 20, the fixing of the toner image t on the surface of the recording material P is performed by pressing and heating the toner image to melt the toner. That is, the fixability has a close relationship with the pressing force and the heater temperature.

Therefore, the heating resistor 3 of the heater 1
The fixing property and the heater are located at a position corresponding to the portion where the pressing force is highest in the center of the width region of the fixing nip portion N formed by pressing the heater 1 and the pressure roller 11 with the film 10 interposed therebetween. It is desirable in terms of thermal efficiency.

However, in the case of the above-described heater 1 of a plurality of energized heating resistors, for example, with respect to the heater 1 of the two energized heating resistors shown in FIGS.
Since the resistor-formed surface of the substrate 1 on which the two energized heating resistors 3a and 3b are formed is covered with an overcoat layer 6 of glass or the like, as shown in FIG.
The surface portion of the overcoat layer between the current-carrying heating resistors 3a and 3b has a concave shape, and the concave portion a corresponds to the center of the width region of the fixing nip portion N.

The current supply to the two current-carrying heating resistors 3a and 3b is selectively performed so that the temperature detected by the thermistor 7 as a temperature detecting element on the back of the heater substrate becomes a set temperature. In other words, as described above, four patterns of energizing both of the two energizing heating resistors 3a and 3b, energizing only one of them, energizing only the other, and non-energizing both are selectively made. The portion where the pressing force is high in the fixing nip portion N does not always become the heat generating portion at that moment.

As an example of an energizing pattern, when energization to one of the energizing heating resistors during paper passing is continuous, even if the temperature detected by the temperature detecting element 7 converges to the set temperature, the width of the heater 1 is reduced. There is a temperature gradient in the direction.

In this state, the nip portion on the side of the energized heating resistor that is energized mainly controls fixing. When the state changes from this state to a state in which power is supplied to the opposite energized heating resistor side, the nip portion mainly responsible for fixing also moves to the opposite energized heating resistor side. During this time, the recording material P passing through the fixing nip portion N may cause defective fixing due to a change in the temperature gradient in the width direction of the heater 1.

The same can be said for the heater shown in FIG. 28 having three or more energized heating resistors.

[0045]

(B) As described in (A) above, the current-carrying heating resistor of the heater is located at the position corresponding to the portion where the pressing force is highest at the center of the width region of the fixing nip N. Although it is desirable in terms of the fixing property and the thermal efficiency of the heater, in the case of the heater 1 having two energized heating resistors, the two energized heating resistors 3a and 3b are positioned at the center of the width region of the fixing nip N. And the portions 3a and 3b are selectively energized so that a portion having a high pressing force does not always become a heat generating portion at that moment.
Since the concave portion a (FIG. 25) of the overcoat layer 6 between the current-carrying heat generating resistors 3a and 3b corresponds to the center of the width region of the fixing nip N, sufficient fixing performance and thermal efficiency can be obtained. In addition, the heat generating portion and the recording material are not sufficiently adhered to each other, and cause wrinkles and paper jam of the recording material after fixing.

[0047]

(C) Current-generating resistors In a plurality of types of heaters, the current-generating resistors having different resistance values may be Ag.
In order to form the resistive material such as / Pd in one pattern printing process, the width of each resistor must be changed. As a result, the area in the heater width direction in which the resistor group is present expands, and the heater 1 has a more complicated temperature distribution in the heater width direction than the conventional heater substrate including a single resistor. In this case, stable heat cannot be supplied to the area where fixing occurs, and fixing failure is likely to occur.

When a resistor is formed by printing, there is a limit to the width of the resistor that can be produced due to printing conditions and the like, and there is an upper limit to the resistance value of the resistor. for that reason,
A resistor having a high resistance value necessary for performing more precise control cannot be manufactured.

In addition, since the resistors having different resistance values are individually driven and controlled, the temperature distribution in the heater surface tends to be non-uniform.

Further, the other end of the connection portion of the resistor requires a plurality of electrode terminals in order to independently supply current to each resistor. In addition, since a current of several amperes flows through each resistor, a large contact area is required to obtain the connection reliability, and the heater outer shape must be enlarged only for the electrode terminals. Disappears.

[0052]

(D) Heating Resistors for Multiple Types of Heating The current control circuit 13 for each heating resistor is connected to each of the resistors in order to change the load resistance.
Switch elements such as R and triac, wiring and connectors must be provided, which increases costs.

[0054]

SUMMARY OF THE INVENTION Therefore, the present invention has
Heater with two heating resistors added, heating
With the aim of providing a heater with multiple resistors
I do.

[0055]

The present invention is a heater characterized by the following constitution.

[0056]

(1) Two heaters are provided on the surface of an electrically insulating substrate, and the heaters that generate heat by selectively energizing the heaters are used to generate heat. A heater characterized in that a substrate surface portion between heat generating resistors is formed as a convex portion.

(2) Two energizing heating resistors are provided on the surface of an electrically insulating substrate, and the two energizing heaters generate heat by selectively energizing the energizing heating resistors. A heater characterized in that a heat conductor having electrical insulation is provided on a substrate surface portion between heat generating resistors, and the substrate surface has a convex shape.

(3) Two energizing heating resistors are provided on the surface of an electrically insulating substrate, and the two energizing heaters generate heat by selectively energizing the energizing heating resistors. A heater characterized in that a surface height of a portion between two current-carrying heating resistors of an electrically insulating overcoat layer provided on a surface of a substrate on which a heating resistor is formed is higher than other portions.

[0060]

[0061]

(4) At least two or more energized heating resistors are provided on the surface of an electrically insulating substrate, and the energized heating resistors are selectively energized to generate heat. A heater characterized in that only two energizing heating resistors on both outer sides forming an outer periphery of a body group are connected by conducting one end and the other end thereof to a common energizing electrode terminal.

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[Action]

[0069]. Regarding a heater with two energized heating resistors, a. A substrate surface portion between the two energized heating resistors is formed as a convex portion (claim 1) . B. Alternatively, a heat conductor having electrical insulation is provided on a portion of the substrate surface between the two energized heating resistors to make the substrate surface convex (claim 2) . C. Alternatively, the surface of the electrically insulating overcoat layer provided on the surface of the substrate on which the two current-generating heating resistors are formed is formed so that the surface height of the portion between the two current-generating heating resistors is higher than other portions ( According to the third aspect , the width of the fixing nip corresponding to the substantially central projection in the width direction of the heater becomes the center of the nip where the pressing force is the highest, the thermal efficiency and the fixing property are improved, and the heater is introduced into the apparatus. The occurrence of wrinkles and paper jams of the recording material as the material to be heated is prevented. The heat transfer efficiency to the central portion in the width direction of the fixing nip portion is improved by making the convex portions have better thermal conductivity than the substrate.

[0070]

[0071]

[0072]

[0073]

[0074]. By connecting both ends of the two resistors of the two outer forming an outer shell of the resistor group to the respective common electrode terminal (claim 4), the both outer two resistors of the resistor group shell was simultaneously energized Noboru Let warm. The temperature of the inner resistor is raised by energizing independently. By doing so, the temperature in the width direction of the heater is made uniform by raising the temperature simultaneously on both sides in the width direction of the heater. By simultaneously energizing the two outer resistors on the outer sides of the resistor group, the number of switches can be reduced and the temperature distribution of the resistor group can be eliminated. For this reason, it is possible to prevent the toner from being defectively fixed due to the non-uniform temperature distribution, thereby improving the fixing property.

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

Embodiment 1 <Example 1> (FIGS. 1 to 4) The present embodiment relates to a heater of a plurality of types of energized heating resistors, the back side of the substrate corresponding to the formation position of each energized heating resistor on the substrate surface side. By disposing a temperature detecting element for detecting the temperature of the heater at each position, a large change in the temperature gradient in the heater width direction is prevented.

(1) FIG. 1 shows the heater 1 of the two-type current-generating resistor shown in FIGS. 25 to 27 described above, which corresponds to the formation position of the individual current-generating resistors 3a and 3b on the front side of the substrate 2. FIG. 9 is a rear view of the heater in which two temperature detecting elements 7a and 7b for detecting the temperature of the heater are arranged at side positions. FIG. 2 is a schematic cross-sectional view taken along line (2)-(2) of FIG. The same components and portions as those of the heater 1 in FIGS. 25 to 27 are denoted by the same reference numerals, and the description thereof will not be repeated.

The temperature detecting elements 7a and 7b are arranged at the above-mentioned positions on the back side of the substrate by adhesion or fixing with screws. As the temperature detecting elements 7a and 7b, a thermistor or the like whose resistance value changes with temperature is used.

Reference numerals 71a, 71b and 71d denote temperature detecting elements 7
These are conductor wirings connected to a and 7b. Among them, the conductor wires 71a and 71b are individual wires for one terminal of each of the temperature detecting elements 7a and 7b, and 71d is a common wire for each other terminal.

As shown in FIG. 3, one end 71 of the wiring of the temperature detecting element 7 is connected to the DC power supply V _CC , and the other end 71 is grounded via the fixed resistor 21 having a small temperature coefficient and arranged at a position away from the heater. When it is connected to (GND), the voltage between the temperature detecting element 7 and the fixed resistor 21 can be detected as the temperature of the temperature detecting element from the relationship between the temperature of the temperature detecting element and the resistance value.

Therefore, in the heater 1 of FIG. 1, the two temperature detecting elements 7a and 7
The common wiring 71 among the wirings 71a, 71b, 71d of b
d is for DC power supply (V _cc ) connection, and individual wiring 71a
1b is connected to ground (GN) via a fixed resistor (21).
D), each temperature detecting element 7a
7b, the respective heating resistors 3a, 3b of the heater 1
The temperature in the vicinity can be detected independently.

The control of energization of the energizing heating resistors 3a and 3b is the same as that of the heater 1 of FIG. That is, both of the two heating resistors 3a and 3b are energized, half energized, only one energized, and only the other energized for each half cycle of the AC power supply so that the temperature detected by the temperature detecting element becomes the set temperature. , Both selectively control four types of energization patterns that are not energized.

Here, the average value of the detected temperatures of the two temperature detecting elements 7a and 7b is compared with the set temperature by using the average value of the detected temperatures as the heater temperature, and the above four kinds of energization patterns are selectively controlled. Further, the difference between the detected temperatures of the two temperature detecting elements 7a and 7b is defined as a temperature gradient in the width direction of the heater. An energization pattern obtained by calculating from the average temperature is corrected so as to energize the resistor 7a or 7b, and is used as an energization control signal for the energized heating resistor.

As a result, the temperature gradient in the width direction of the heater is prevented from greatly changing, and in the image heating / fixing apparatus, it is possible to eliminate the occurrence of fixing defects such as uneven fixing due to the temperature gradient.

(2) FIG. 4 shows the back surface of the substrate corresponding to the formation position of each of the current-carrying heating resistors 3a, 3b, and 3c on the front surface side of the substrate 2 for the three-heating-type heater 1 shown in FIG. FIG. 7 is a rear view of a heater in which three temperature detecting elements 7a, 7b, and 7c for detecting the heater temperature are arranged at side portions. The control of energization of each energized heating resistor of the heater and the control of the heater temperature are the same as those in FIG.

<Embodiment 1> (FIGS. 5 to 7) This embodiment corresponds to the first to third aspects of the present invention.
Regarding a heater with two energized heating resistors, a. Make the substrate surface portion between the two energized heating resistors a convex portion b. Alternatively, a heat conductor having electrical insulation is provided on the surface of the substrate between the two energized heating resistors to make the substrate surface convex. C. Alternatively, the surface of the electrically insulating overcoat layer provided on the surface of the substrate on which the two current-generating heating resistors are formed is formed to have a higher surface height between the two current-generating heating resistors than other portions. This is an example in which the fixing property and the thermal efficiency are improved, and wrinkles and paper jams of the recording material are eliminated.

(1) FIG. 5 shows the heater 1 of the two-type heating resistor shown in FIGS. 25 to 27 described above, in which the central portion in the width direction on the front surface side of the substrate 2 is formed into a convex portion 2a along the length of the substrate. FIG. 3 is a cross-sectional model view of two electric heating resistors 3a and 3b formed on both sides of a substrate with a convex portion interposed therebetween and an electrically insulating overcoat layer 6 formed on the surface of the substrate. is there. Figure 2 shows other heater configurations and energization controls
Same as heaters 5 to 27.

The protruding portion 2a is set to have a width of about 0.3 to 0.5 mm and a height of about 10 to 20 μm.
・ Thickness of 3b is about 10 μm).

Due to the presence of the convex portion 2a, the heater 1 has two current-generating heating resistors 3a and 3b which are substantially central portions in the heater width direction corresponding to substantially central portions of the fixing nip N width region. It has a shape with a protruding portion between them.

Therefore, the substantially central portion of the width region of the fixing nip portion N corresponding to the substantially central protruding portion in the width direction of the heater 1 becomes the nip center where the pressing force is the highest, thereby improving the thermal efficiency and the fixing property. It is possible to prevent wrinkles and paper jams of the recording material introduced as the heated material.

(2) FIG. 6 shows a configuration in which the convex portion 2a of the heater 1 of FIG. 5 is replaced with a convex portion 2b of a heat conductor having electrical insulation. The same effect can be obtained, and the heat transfer efficiency to the central portion in the width direction of the fixing nip portion N is improved by making the convex portion 2b have better thermal conductivity than the substrate 2.

For example, the substrate 2 is made of alumina or the like, which has poor thermal conductivity, and the convex portion 2b is made of aluminum nitride or the like having good thermal conductivity, so that the heat generating resistors 3a.
The heat generated in the fixing nip N is transmitted to the central portion in the width direction of the fixing nip N with high efficiency through the convex portion 2b of the heat conductor, and is more efficiently used for heat fixing of the toner image.

(3) FIG. 7 shows that the heater 1 of the above-described two energized heating resistor type shown in FIGS. 25 to 27 is formed by forming an overcoat layer 6a on the electrically insulating overcoat layer 6 again. The surface height of the overcoat layer between the current-carrying heating resistors 3a and 3b is higher than other portions.

This heater has the same effect as the heater 1 of FIG. Although this heater is inferior in heat efficiency to that of FIG. 6, it has a simpler structure than the heaters of FIGS. 5 and 6, and does not require a special process in manufacturing.

<Reference Example 2>

The heater 1 shown in FIG . 8 has the following configuration.
(A) is a partially cutaway plan view of a heater, and (b) is a cross-sectional model diagram along the bb line of (a). Fig. 2
Regarding the heater 1 of 5 to 27 current-generating heating resistor two-types, first, a common electrode terminal 4 and two individual electrode terminals 5a and 5b
Is formed by printing using a silver paste and semi-baked.

Next, one of the energized heating resistors 3a is conducted to the two electrode terminals on the substrate surface between the common electrode terminal 4 and one of the individual electrode terminals 5a, and the resistance ρ of Ag / Pd is used. It is formed by printing in a narrow band shape with a width W and a thickness t so as to have a resistance R with respect to the effective length L of the heater portion. At this time, the relationship between the resistance value R and each dimension is as follows: R = ρ · L / (W · t)

Next, the other current-generating resistor 3b is placed in parallel with the printed current-generating resistor 3a and the common electrode terminal 4
And the other individual electrode terminal 5b is electrically connected to the two electrode terminals on the substrate surface, and the width W is determined using Ag / Pd having a resistivity of 2ρ.
-It is formed by printing in a narrow band shape so as to have a thickness t. The gap between the two energized heating resistors 3a and 3b is set to a gap Gap that does not cause a short circuit. At this time, a counterbore portion is provided on the printing plate so as not to destroy the energized heating resistor 3a formed earlier.

Next, an overcoat layer (low-melting glass) 6 is provided on the surface of the substrate on which the energized heating resistors 3a and 3b are formed, except for the electrode terminals 4.5a and 5b, and the entire substrate is subjected to a final firing treatment. . Further, a temperature detecting element 7 is provided on the back surface of the substrate 2.

The heater 1 of this embodiment has the same width W between the two current-carrying heating resistors 3a and 3b, even though the resistance values of the two heating resistors 3a and 3b are twice as large. As shown in FIG. 26, when two energized heating resistors having a double resistance difference are formed in a single printing process by using an energized heating resistor material (paste) having the same resistivity as in the related art. The widths of the resistors 3a and 3b are 2W and W, respectively.

In the heater 1 manufactured in this embodiment , the common electrode terminal 4 of the two energized heating resistors 3a and 3b is connected to one terminal of the power source, and the individual electrode terminals 5 of the resistors 3a and 3b are connected.
a.5b is connected to the other terminal of the power supply via a switch, and the switch is selectively opened and closed to change the load resistance of the heater to control the amount of heat generated.

As described above, it is possible to suppress the expansion of the width of each of the resistors 3a and 3b by using the resistors having different resistivity. As a result, the width of the heat generating region of the heater is reduced, the heat response is high, and the heater has a stable temperature distribution in the heat generating region, and the fixing performance is improved.

That is, if a resistor material having a different volume resistance value is used as the material of the resistor and each resistor is formed by a plurality of printing steps, the required resistance value is satisfied, and the resistance is further increased. A heater with a narrow body is obtained. Therefore, the width in which the resistors are present is suppressed, and all the resistors are present in the area (in the fixing nip portion N) where the pressure is applied by the pressure roller, so that stable fixing properties can be obtained.

For example, when an Ag / Pd alloy is used as the material of the resistor, the sheet resistance value has a width of 10 to 40 [mΩ / □] depending on the alloy components and firing conditions.

[0110] Also, generally as other thick-film _{resistor, Ru0 2 (3.5E-5Ω ·} cm), Ir0 2 (4.9E-5Ω · cm), LaRu0 3 (4.5E-3Ω · cm), _{CaRu0 3 (3.7E-3Ω · cm} ), Bi 2 Ru 2 0 7 (2.3E-2Ω · cm), Pb 2 Ru 2 0 6 (2.0E-2Ω · cm), LaB 6 (17.4E −6 Ω · cm), PrB ₆ (19.5E−6 Ω · cm), NdB ₆ (20.0E−6 Ω · cm), and the like. These thick-film resistors (pastes) can change the low efficiency by the compounding ratio of the conductive particles and the glass frit.

Although the number of resistors is two in this embodiment , the number may be more than two. Also, it is obvious that the greater the number of resistors, the higher the accuracy of the temperature control.

Reference Example 3 (FIGS. 9 and 10) (1) The heater 1 in FIG. 9 has the following configuration. In the heater 1 of this reference example, three energized heating resistors 3a, 3b, and 3c are formed in the center of the substrate 2 in the width direction in the longitudinal direction of the substrate by printing in the same manner as the conventional heater. . One end of each of the three energized heating resistors 3a, 3c, 3b is connected to the common electrode terminal 4, and the other end is connected to individual electrode terminals 5a, 5c, 5b, respectively.

The common electrode terminal 4 is connected to one terminal of the power supply, and the individual electrode terminals 5 of the current-generating heating resistors 3a, 3c and 3b are connected.
a, 5c and 5b are respectively connected to the other terminals of the power supply via switches, and the switches are selectively opened and closed to change the load resistance of the heater to control the amount of heat generated.

In this embodiment , three parallel heating resistors 3 are provided.
a, 3c and 3b, the length of the central heating resistor 3c is increased by making it a waveform pattern to increase the length of the resistor 3c.
The resistance value of c is increased.

This is because the heating value of the resistor is generally W = V
2 / R, and the larger the value of R, the smaller the calorific value. Therefore, a resistor having a large resistance value is required to perform high-precision temperature control. In order to increase the resistance value in a limited substrate size, there is a method of narrowing the width. However, the reduced width increases the risk of breakage in reliability.

Therefore, by forming the resistor in such a waveform pattern as long as the reliability can be ensured, it is possible to control the temperature with high reliability and high accuracy, and to improve the fixing performance.

That is, by making the pattern of the resistor into a waveform, it is possible to increase the resistance value per unit length in the contact length as the heater. Since Power = V2 / R, higher-precision control is possible.

(2) The heater 1 shown in FIG. 10 has two current-generating resistors 3a and 3b in parallel, and the two end portions 3b 'and 3b' of one of the resistors 3b have waveform patterns.

As described in the above (1) , a higher resistance value is required to perform more accurate temperature control. on the other hand,
At both ends of the heater, the temperature is lower than at the center due to the terminal effect. Therefore, if the area where the resistor is present at both ends is increased by forming the both ends in a wave shape, the amount of heat generated in that area increases, and the effect of the terminal effect is corrected, and the center and end portions in the longitudinal direction of the heater are corrected. The temperature difference can be eliminated, the temperature distribution in the longitudinal direction of the heater becomes uniform, and the fixing performance is further improved.

<Embodiment 2> (FIG. 11) This embodiment corresponds to the invention of claim 4, and FIG.
One heater 1 has three parallel heating resistors 3a and 3c.
3b, one end of the three resistors 3a, 3c and 3b is connected to the common electrode terminal 4, and the other end is a common terminal of the two resistors 3a and 3b on both outer sides. 5d
The other end of the central resistor 3c is connected to an independent electrode terminal 4c provided on the back side of the substrate 4 through a through hole h.

As described above, a through hole is provided in the substrate until each resistor is electrically connected to an independent electrode terminal, and one part is provided on the rear surface of the substrate opposite to the surface on which the resistor is formed. By providing the electrode terminal portion, the area of the electrode terminal portion can be widened, and a reliable heater can be obtained without increasing the size of the substrate.

The two outer resistors 3a on the outer sides of the resistor group consisting of the three parallel resistors 3a, 3c, 3b
By connecting both ends of 3b to the common electrode terminals 4 and 5d respectively, the two outer resistors 3 on both sides of the resistor group outer shell
a. 3b are simultaneously energized to raise the temperature. Central resistor 3c
Are independently heated to raise the temperature. By doing so, the temperature in the width direction of the heater is made uniform by raising the temperature simultaneously on both sides in the width direction of the heater.

That is, the common electrode terminal 4 at one end of the three resistors 3a, 3c and 3b is connected to one terminal of the power supply,
Common electrode 5d on the other end and independent electrode terminal 5c of resistor 3c
Is connected to the other terminal of the power supply via a switch, and the switch is selectively opened and closed to change the load resistance value of the heater to control the amount of heat generated.

At this time, by simultaneously energizing the two outer resistors 3a and 3b forming the outer contour of the resistor groups 3a, 3c and 3b, the number of switches can be reduced, and the temperature distribution of the resistor group can be reduced. You can eliminate leaning. For this reason, it is possible to prevent the toner from being defectively fixed due to the non-uniform temperature distribution, thereby improving the fixing property.

Reference Example 4 (1) The heater 1 of FIG. 12 has the following configuration.

The common electrode terminal 4 on one end of the surface of the substrate 2 is formed into a pattern provided with a strip-shaped extended electrode portion (wiring portion) 41 with the center in the width direction of the surface of the substrate 2 facing the other end of the substrate. Further, the two individual electrode terminals 5a and 5b on the other end side of the substrate are substantially parallel to the extension electrode portion 41 at predetermined intervals on both sides of the extension electrode portion 41 of the common electrode terminal 4, respectively. A pattern is provided with strip-shaped extension electrode portions (wiring portions) 51a and 51b directed to the side, and these electrode terminals 4.5a and 5b and extension electrode portions 41 and 51a are provided.
-Print 51b on the surface of the substrate 2 with silver paste.

Next, between the extension electrode portions 41 and 51a, and
1 and 51b, the two electrode portions 41 and 51a, 41, respectively.
The energization heating resistors 3a and 3b are formed by printing along the length of the electrode portion over the 51b. The electric heating resistors 3a and 3b may change the resistivity of each other like the heater (1).

Next, the common electrode terminal 4, the individual electrode terminal 5a
-The overcoat layer 6 is formed on the surface of the substrate except for the portion 5b and baked. The temperature detecting element 7 is provided on the back surface of the substrate.

The heater 1 manufactured as described above has a large area where the resistors 3a and 3b and the electrodes 51a and 41 and 51b and 41 are connected to each other. There is no breakage, and the reliability of the heater is improved.

As described above, by forming the resistors between at least one pair of electrode (wiring) patterns drawn opposite to each other, at least two or more pairs of resistors are obtained.
At this time, the resistance value can be changed by changing the distance between the opposing electrodes. Further, in this method, the resistor can be formed by one-time printing of the resistor, and the resistor has two resistance values on one peak. Can be obtained. Therefore, the temperature distribution becomes uniform.

(2) The heater 1 shown in FIG. 13 is the same as the heater shown in FIG.
・ Put 51b so as to cover all these electrodes
By printing one resistive material pattern 30, resistor portions 3a and 3b having different resistance values are formed between the extended electrode portions 51a and 41 and between the extended electrode portions 41 and 51b.

By configuring the heater in this manner, the unevenness of each of the resistors 3a and 3b is eliminated, the pressure distribution in the fixing nip N is made uniform, and the fixability is improved. Also, 1
When two resistors have two resistance values, the temperature distribution is made uniform, and the fixability is improved.

(3) In the heater of FIGS. 12 and 13, the extended electrode portions 41 and 51 of the electrode terminals 4.5a and 5b.
By changing the distance between a, 41 and 51b depending on the location as shown in FIG. 14, it is possible to change the resistance value of the current-carrying heating resistors 3a and 3b formed between those distances depending on the location. It is also possible to correct the temperature drop at both ends of the heater due to the terminal effect.

(4) As shown in FIG. 15, each electrode terminal 4
Protrusions are provided along the length of the extension electrode portions 51a, 41, and 51b of 5a and 5b to form a comb-teeth shape, and the extension electrode portions 41 are formed.
It is also possible to control the interval between 51a, 41 and 51b to provide a more accurate resistance value distribution.

(5) In order to make the flow of current more uniform, as shown in FIG. 16, the electrode terminals 4.5a, 5b,
A through hole h is provided at the end of each of the extension electrode portions 41, 51a, and 51b, and the auxiliary extension electrode portion 41 'is also provided on the back side of the substrate 2.
· 51a 'and 51b' may be provided.

(6) Further, as shown in FIG. 17, even if the extended electrode portions near the electrode terminals 4.5a and 5b where the current is concentrated are expanded, the extended electrode portions 4151a and 411.5 are formed.
Since there is no effect on the resistance value formed between 1b, the terminal effect is corrected, and furthermore, the occurrence of pattern breakage due to current concentration is prevented, and the reliability of the heater is improved.

With the heater configuration as described in (1) to (6) above, it is possible to arrange a resistor group composed of resistors having different resistance values at a high density, and to control the temperature of the resistor group. It is possible to make the distribution uniform.

Further, it is possible to set the resistance value over a wider range, and it is possible to control the temperature with high accuracy by expanding the control range.

Further, the value of the current supplied to each independent electrode terminal is smaller than that of the heater substrate composed of one resistor, so that the allowable current value required for the connection can be reduced, and the reliability of the connection can be reduced. Higher.

< Embodiment 5> (FIGS. 18 and 19) In this embodiment, a current supply control circuit system for a current-carrying heating resistor is configured at a low cost for a heater having a plurality of current-carrying heating resistors.

The actual use state of the heater is rapidly raised mainly from a room temperature state to a predetermined temperature, and the temperature is controlled so that there is no temperature ripple. Alternatively, the temperature is raised from a state higher than room temperature to a predetermined temperature, and control is performed so that there is no temperature ripple.

From the relationship of Power = V.V / R, the load resistance R is small when a large Power is required. That is, a plurality of resistors are connected in parallel to reduce the resistance value. On the other hand, when a small power is required, only a resistor having a high resistance value is energized.

That is, when the actual use state and the control state are combined, when the temperature is raised, the state is a parallel state. In addition, since it is necessary to prevent the overshoot from the predetermined temperature, the state is changed to the single resistance state before the predetermined temperature. Switch. Then, in a state where the temperature is controlled so as not to cause a ripple at a predetermined temperature, it is necessary to turn on and off the high-resistance element alone and finely. In addition, when starting from a temperature higher than room temperature, if the temperature difference from the predetermined temperature is small, the required Power is small.

That is, the switching from the parallel resistance state to the single resistance state is determined by the temperature, and the speed required for the switching is not fast, and does not need to be performed by an electric switch.

Therefore, two metals made of different materials having different coefficients of thermal expansion are bonded to each other to form a bimetal that is curved by thermal expansion, or a shape memory alloy whose shape changes with temperature. If a switch for short-circuiting the other end of the resistor group is formed and arranged on the heater, the number of expensive electric switches (SSR, triac, etc.) can be reduced, and the cost can be reduced.

If the same number of electrical switches are used,
The number of high resistance elements can be increased, and more accurate temperature control can be performed.

With the above configuration, the load resistance value of the heater can be changed for each half-wave of the power supply waveform, the control response of the supply electrode to the detected temperature value of the heater can be improved, and the conventional phase control method can be used. In a temperature control device that does not generate switching noise as described above, a heater with lower cost and higher temperature stability can be obtained.

FIG. 18 shows the heater of the three energized heating resistor type shown in FIG.
The three individual electrode terminals 5a, 5c, and 5b are short-circuited by attaching a bimetal switch 21 that opens at 0 to 140C. FIG. 19 shows an equivalent circuit at this time.

In this embodiment , when the temperature is raised from room temperature, this switch 21 is short-circuited, and the total resistance value is R = R1 · R2 · R3 / (R1 + R2 + R3), and P = V · (R1 + R2 + R3) The temperature rises rapidly with / (R1, R2, R3).

Next, when the temperature reaches about 100 ° C., the switch 21 opens, and R = R1 · R2 / (R1 + R2), P = V · (R1 + R2) / (R1 · R2). If the temperature is raised to about this temperature, control from there can be sufficiently performed by the two resistors 3c and 3a.

Further, at the time of continuous energization, the temperature is on the high temperature side,
This switch 21 remains open. On the other hand, stop energizing,
When the temperature of the ceramic substrate 2 decreases, the switch 2
1 is closed again, and the resistors 3a, 3c and 3b are short-circuited. When restarting, the load resistance value is low and the resistor 3a, 3c and 3b rises rapidly with large power.

With such a configuration, it is possible to reduce the number of SSRs and a part of the control circuit compared to the circuit configuration as shown in FIG. 28, thereby reducing the cost.

It is obvious that the same effect can be obtained if the number of the resistors is two or more, and the shape is arbitrary as long as it has a switch function of opening and closing at a predetermined temperature.

If the switch 21 is made of a shape memory alloy, it is possible to satisfy the opening / closing function by temperature even if the switch 21 has a more complicated shape than a switch using a bimetal. It is possible to do. The opening and closing temperature can be set more finely by changing the alloy ratio.

As described above, by changing the switch of the portion where the switching speed may be slower from the electric switch to the mechanical switch, a heater with lower cost can be obtained. Further, if the same number of electrical switches as in the related art are used, temperature control at a set temperature can be performed with higher accuracy.

[0156]

As described above, according to the heater of the present invention having a plurality of energized heating resistors, it is possible to prevent the temperature gradient in the heater width direction and the longitudinal direction from greatly changing, and to provide an image heating and fixing apparatus. In addition, it is possible to eliminate the occurrence of fixing unevenness or the like due to the temperature gradient, to ensure sufficient thermal efficiency and fixability, and to prevent wrinkles and paper jams of the recording material introduced as a material to be heated introduced into the apparatus. Effects such as accurate energization control and temperature control, downsizing of the heater itself, simplification of the energization control circuit system and low cost can be obtained.

[Brief description of the drawings]

FIG. 1 is a rear view of a heater (part 1) of Reference Example 1.

FIG. 2 is a schematic cross-sectional view taken along line (2)-(2) of FIG.

FIG. 3 is an explanatory diagram of temperature detection.

FIG. 4 is a rear view of the heater of Reference Example 1 (Part 2).

FIG. 5 is a schematic cross-sectional view of the heater (part 1) of the first embodiment.

FIG. 6 is a schematic cross-sectional view of a heater (part 2) according to the first embodiment.

FIG. 7 is a schematic cross-sectional view of a heater (part 3) according to the first embodiment.

8A is a partially cutaway plan view of the heater of Reference Example 2, and FIG. 8B is a schematic cross-sectional view taken along line bb of FIG. 8A.

FIG. 9 is a partially cutaway plan view of a heater (No. 1) of Reference Example 3 .

FIG. 10 is a partially cutaway plan view of a heater (part 2) of Reference Example 3;

11 (a) is part cutaway plan view of the heaters of Example 2, (b) the cross-sectional model view taken along the line b-b of (a)

12A is a partially cutaway plan view of a heater (No. 1) of Reference Example 4, and FIG. 12B is a cross-sectional model view taken along line bb of FIG.

13A is a partially cutaway plan view of a heater (part 2) of Reference Example 4, and FIG. 13B is a cross-sectional model view taken along line bb of FIG.

FIG. 14 shows patterns of electrode terminals and auxiliary electrode portions of a heater (part 3) of Reference Example 4 .

FIG. 15 shows patterns of electrode terminals and auxiliary electrode portions of a heater (part 4) of Reference Example 4 .

16A is a partially cutaway plan view of a heater (No. 5) of Reference Example 4, and FIG. 16B is a cross-sectional model view taken along line bb of FIG.

FIG. 17 shows patterns of electrode terminals and auxiliary electrode portions of a heater (part 6) of Reference Example 4 .

FIG. 18 is a partially cutaway plan view of a heater according to a fifth embodiment, and a circuit diagram of a current supply control circuit.

FIG. 19 is an equivalent circuit diagram.

FIG. 20 is a schematic cross-sectional view of a main part of an example of a film heating type image heating fixing device.

FIG. 21 is a partially cutaway plan view of a heater, and an energization control circuit diagram.

FIG. 22 is a rear view of the heater.

FIG. 23 is a current waveform diagram of zero-cross wave number control of energization.

FIG. 24 is a current waveform diagram of phase control of energization.

FIG. 25 is a schematic cross-sectional view of a main part of an example of a film heating type image heating and fixing device using a heater of two types of energized heating resistors.

FIG. 26 is a partially cutaway plan view of the heater.

FIG. 27 is a rear view of the heater.

FIG. 28 is a partially cutaway plan view of a heater with three energized heating resistors and an energization control circuit diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heater 2 Heater board 3.3a-3c Electric heating resistor 4,5,5a-5c Electrode terminal for electricity 6 Heater overcoat layer 7 Heater temperature detecting element 8 Heater holder 10 Heat resistant film 11 Pressure roller P Recording material as heating material t Unfixed toner 12 Power supply 13.14 Energization control circuit N Fixing nip

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-248085 (JP, A) JP-A-4-81877 (JP, A) Fully open 48-19241 (JP, U) Really open Showa 59- 150194 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 3/00 H05B 3/20 G03G 15/20

Claims (4)

(57) [Claims] 1. A heater in which two energized heating resistors are provided on the surface of an electrically insulating substrate and heat is generated by selectively energizing the energized heating resistors.
A heater characterized in that the surface of the substrate between the current-carrying heating resistors is formed as a convex portion. 2. A heater in which two energized heating resistors are provided on the surface of an electrically insulating substrate and heat is generated by selectively energizing the energized heating resistors.
A heater characterized in that a heat conductor having electrical insulation is provided on a portion of a substrate surface between the current-generating heating resistors, and the surface of the substrate has a convex shape. 3. A heater in which two energizing heating resistors are provided on the surface of an electrically insulating substrate and heat is generated by selectively energizing the energizing heating resistors.
The electrically insulating overcoat layer provided on the surface of the substrate on which the current-generating heating resistors are formed is characterized in that the surface height of the portion between the two current-generating heating resistors is formed higher than other portions. heater. 4. A heater in which at least two or more energized heating resistors are provided on the surface of an electrically insulating substrate and heat is generated by selectively energizing these energized heating resistors. A heater characterized in that only one of the two outer heating resistors forming the outer periphery of the group is connected to one end side and the other end side of each of them by conducting to a common energizing electrode terminal.