JP2002359059A - Heater with current-carrying cutoff function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heater with a current-carrying cutoff function having the self-cutoff function causing no firing, fuming, and electric shock when the temperature rises exceeding the reference value. SOLUTION: This heater 1 with the current-carrying cutoff function has a circuit board 11 composed of a metal material (such as stainless steel) or an inorganic material (such as alumina), an insulating layer 12 formed on the board 11, and a resistor pattern 14 formed on the insulating layer 12. At least a part on the heater resistor pattern 14 forms a cutoff part (such as lead glass) for cutting off current-carrying by becoming an insulator by reacting with a component (such as silver-palladium) for constituting the resistor pattern 14 when reaching the prescribed temperature. A protective layer 16 and an overcoat layer 17 may be successively laminated on the resistor pattern 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater with a power cutoff function, and more particularly, to a heater with a power cutoff function having a self-disconnection function that does not generate fire, smoke, or electric shock when a temperature rise exceeds a reference value. . The heater with an energization shut-off function of the present invention is suitably used for fixing a toner in a copying machine and a laser printer, or for drying a paint.

[0002]

2. Description of the Related Art In equipment provided with a heater, when an abnormality occurs, the temperature may exceed a reference value and rise.
As a result, there is a problem that smoke or fire is caused, and parts surrounding the heater are ignited. In order to prepare for such abnormalities, a temperature fuse is provided in the power supply circuit to the heater together with the temperature control device, and when a temperature rise exceeds a predetermined reference value, the temperature fuse is blown to cut off the power supply circuit. I have. However, since this method is secondary, it is required to add a self-disconnection function to the heater itself in order to further enhance safety.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and achieves fail-safe even for a single heater, and generates fire, smoke and electric shock when the temperature rises above a reference value. It is an object of the present invention to provide a heater with an energization shut-off function having a self-disconnection function that does not cause a disconnection.

[0004]

Means for Solving the Problems The present inventor has studied the method of adjusting the electric resistance value for obtaining a heating element having an electric resistance value within the product standard, the heating element and the manufacturing method thereof, and as a result, completed the present invention. I came to. That is, a heater with an energization cutoff function of the present invention includes a substrate made of a metal material or an inorganic material, an insulating layer formed on the substrate, and a resistor pattern formed on the insulating layer. In the above, at least a part of the resistor pattern that generates heat is provided with a cut-off portion that, when a predetermined temperature is reached, reacts with a component constituting the resistor pattern to become an insulator and cut off electricity. It is characterized by.

[0005] A protective layer can be further provided on the resistor. Further, an overcoat layer can be provided on the protective layer.

The material constituting the substrate is not particularly limited as long as it has been conventionally used as a heater material. Examples thereof include stainless steel and the like as the metal material, and ceramics and the like as the inorganic material. Among these, ferritic heat-resistant steel is preferable as stainless steel. Further, examples of the ferritic heat-resistant steel include SUS430, SUS444, and SUS436, and SUS430 and SUS444 are preferable. In addition, examples of the inorganic material include alumina and aluminum nitride.

The components constituting the insulating layer are not particularly limited, but need to be selected in consideration of the thermal expansion balance with the material constituting the substrate. For example, when the substrate is made of stainless steel, glass (which may be crystallized glass or amorphous glass) may be mentioned, but crystallized glass or semi-crystallized glass is preferred. At this time, the components constituting the glass are also not particularly limited, and a glass having a softening point of preferably 600 ° C. or higher, more preferably 650 ° C. or higher, and further preferably 700 ° C. or higher is preferable. Glasses having such properties include SiO ₂ —Al ₂ O ₃ —R
O-based glass [RO is an oxide of alkaline earth metal (Mg
O, CaO, BaO, SrO, etc.). And the like. Further, the thickness of the insulating layer is not particularly limited,
Preferably from 60 to 120 μm, more preferably from 70 to 1 μm.
It is 10 μm, more preferably 75-100 μm.
When the material forming the substrate is an inorganic material, the substrate may or may not include the insulating layer.

The resistor pattern is formed by combining straight lines, curves, and various shapes according to the purpose, but the constituent components are not particularly limited. For example, a silver-based material containing silver, RuO ₂ , X ₂ Ru ₂ O _{6 to 7} (X
Is a metal element such as Bi and Pb), Ta ₂ N, and the like. Among these, those containing preferably silver, more preferably those containing silver and palladium, furthermore,
Those containing no lead, cadmium, nickel or the like are preferable.
In particular, a resistor pattern formed of a material containing silver and palladium has a small degree of surface oxidation at the time of heat curing, and easily maintains conductivity. The resistor pattern is printed or the like using a paste containing silver or the like, and is formed by a baking process or the like. The thickness of the resistor pattern is not particularly limited, but is preferably 5 to 30 μm, more preferably 8 to 20 μm, and still more preferably 10 to 15 μm.
m.

The cutoff section cuts off the power supply to the resistor pattern constituting the heater when the heater generates heat and reaches a predetermined temperature abnormally higher than the operating temperature. That is,
When the component constituting the interrupting portion and the component constituting the resistor pattern react at a predetermined temperature, they react to form an insulator, thereby interrupting the energization. In order to use an insulator, a component constituting the resistor pattern is dispersed or the like in a component constituting the blocking portion by a reaction, so that the conductivity of the resistor pattern is impaired. I just need. The component that constitutes the blocking portion is not particularly limited as long as it reacts with the component that constitutes the resistor pattern to become an insulator, and examples thereof include glass. This glass may be crystallized glass or amorphous glass, but Pb-based and / or Bi-based amorphous glass is preferred. The Pb-based glass, PbO-B ₂ O ₃
Glass and the like, and Bi-based glass is Bi ₂
O ₃ -ZnO-B ₂ O ₃ system glass. In addition, Ag-based amorphous glass (for example, AgO—P ₂ O)
_{5 system), P 2 O 5 -SnO 2} -ZnO -based glass, ZnO-B
₂ O ₃ -based glass and the like are also included.

When the component constituting the interrupting portion is glass, the above-mentioned "predetermined temperature" set as the temperature at which energization interruption is desired is determined by the component constituting the insulating layer and the protective layer exemplified below. It is preferably lower than the transition point of the constituent components. At this time, the reaction between the components constituting the resistor pattern and the glass is such that the predetermined temperature is near the transition point of the glass, even near the softening point, or in a molten state at a higher temperature. May be either.
The glass may or may not be crystallized after the reaction.

The interrupting portion may be provided at least partially on the resistor pattern, but may be provided at any number of places. Further, it is preferable that a heater designed according to the application is provided at a position on the resistor pattern where the highest temperature is most likely to be reached. Further, the blocking portion preferably covers 80% or more, more preferably 90% or more, and further preferably 100% of the width direction of the resistor pattern.
The resistor pattern may be covered beyond the width of the resistor pattern. The thickness of the blocking portion is not particularly limited, but is preferably 5 to 100 μm, more preferably 10 to 60 μm, and still more preferably 15 to 40 μm.

The protective layer is provided to protect the resistor pattern, and does not cause abnormal operation of the heater due to deterioration of the resistor pattern due to surface oxidation or the like when the heater is generating heat. Is to do so. The protective layer may be formed so as to cover not only the resistor pattern but also the blocking portion. The component constituting the protective layer is not particularly limited, and examples thereof include glass. This glass may be crystallized glass or amorphous glass. As an example of this, SiO ₂ —Al ₂ exemplified as a component constituting the above-mentioned insulating layer
Si-based glass such as O ₃ -RO-based glass and the like can be mentioned.
When both the component constituting the blocking portion and the component constituting the protective layer are glass, the former preferably has a lower softening point than the latter. The difference between the two temperatures is preferably 500 ° C. or higher, more preferably 400 ° C. or higher, and even more preferably 350 ° C. or higher. Thus, when the heater reaches a predetermined temperature, the power cutoff can be easily performed only by the cutoff portion. Further, the thickness of the protective layer other than the blocking portion is not particularly limited, but is preferably 1
The thickness is 5 to 75 μm, more preferably 20 to 40 μm, and still more preferably 25 to 35 μm.

The above-mentioned overcoat layer may be used if necessary.
It can be provided as a layer or as two or more layers, and is provided mainly for smoothing the heater surface or for preventing dust. The overcoat layer may or may not completely cover the protective layer formed on the resistor pattern and the blocking portion. The component constituting the overcoat layer is not particularly limited, and examples thereof include glass. This glass may be crystallized glass or amorphous glass. An example of this is SiO ₂
—Al ₂ O ₃ —B ₂ O ₃ —RO glass. When both the components constituting the protective layer and the components constituting the overcoat layer are glass, the former preferably has a lower softening point than the latter. The difference between the two temperatures is preferably 400 ° C. or more, more preferably 250 ° C.
The temperature is more preferably 160 ° C. or more. The thickness of the overcoat layer is not particularly limited, but is preferably 10 to 50 μm, more preferably 10 to 40 μm,
More preferably, it is 20 to 30 μm.

The heater with an energization cut-off function of the present invention may have an anti-warpage layer on the back surface in order to reduce dimensional stability of the substrate, for example, warpage of the substrate which may occur when each layer is formed. it can. The component constituting the warpage preventing layer is not particularly limited, but glass is preferable.
The thickness of the warpage prevention layer depends on the material constituting the heater layer and its thickness, but is preferably 25 to 150 μm.
m, more preferably 70 to 140 μm, even more preferably 110 to 130 μm.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described in more detail. Example 1 (1) Production of a heater with an energization cutoff function After smoothing the surface of a SUS430 substrate 11 having a length of 272.5 mm, a width of 8.75 mm and a thickness of 0.6 mm, crystallized glass (trade name “3500N”) (Manufactured by DuPont, transition point: 700 ° C., softening point: 740 ° C.) after drying.
μm and baked at 850 ° C.
A μm insulating layer 12 was provided. Then lead, cadmium,
A circuit pattern as shown in FIG. 1 was printed using a resistor paste containing silver-palladium without nickel, and baked at 850 ° C. to form a resistor pattern 14 (see FIG. 1). The line width is 2.06 mm and the line thickness is 1
1 μm. Furthermore, printing is performed on each terminal portion of the resistor pattern 14 using silver paste as an electrode to form extraction electrode portions 13a and 13b, and a firing process (85)
(0 ° C., 30 minutes). Next, a part (2 mm in length and 2.06 mm in width) of the resistor pattern serving as the blocking portion 15 is masked, and the portion other than the blocking portion is made of crystallized glass used for forming the insulating layer 12. Thus, a protective layer 16 having a thickness of 40 μm was provided. Subsequently, the amorphous glass (SiO ₂ −
Al ₂ O ₃ —B ₂ O ₃ —RO, transition point; 540 ° C., softening point;
(580 ° C.) and baked at 750 ° C.
An overcoat layer 17 of 0 μm was provided. Thereafter, Pb-based amorphous glass notches and became part by masking (PbO-B ₂ O _3, transition point; 310 ° C., a softening point;
(375 ° C.), and baked at 460 ° C. to provide a cut-off portion 15 to produce a heater with an energization cut-off function (see FIGS. 1 and 2).

FIG. 2 is a schematic cross-sectional view of the heater with the power cutoff function obtained above. In FIG. 2, 11 is a substrate, 12 is an insulating layer, 13a and 13b are extraction electrode portions, 14 is a resistor pattern, 15 is a blocking portion, 16 is a protective layer, and 17 is an overcoat layer.

(2) Performance test of the heater The heater with the current blocking function obtained above was applied to the heater circuit by instantaneously applying a voltage of 200 V AC to about 800 ° C. using the apparatus shown in FIG. Then, the time until the current interruption section of the heater was destroyed and the surface temperature of the interruption section at the time of the breakdown were measured. At this time, the current at the time of voltage application and the current at the time of destruction were simultaneously measured. In addition, in order to evaluate the insulation after breakdown, an automatic withstand / insulation tester (TOS8850A) was used.
Using a mold, manufactured by Kikusui Electronics Co., Ltd.)
a and the electrode completely covering the upper surface of the breaking portion 15 were used to measure the withstand voltage of the breaking portion. Table 1 shows the results.

[0018]

[Table 1]

Examples 2 to 4 Pb-based amorphous glass (PbO-B ₂ O ₃ , transition point: 3)
10 ° C., softening point: 375 ° C.). A heater with a cutoff function was manufactured (FIG. 4).
reference). Three heaters were manufactured by changing the film thickness of the overcoat layer 17, and the same evaluation was performed as described above. The results are shown in Table 1. In FIG. 4, for convenience, the same reference numerals are given, and the following other aspects are also the same.

Examples 5 to 7 The glass used for the blocking portion 15 and the overcoat layer 17 was Bi-based amorphous glass (Bi ₂ O ₃ -ZnO-B ₂ O ₃ ,
Transition point; 390 ° C .; softening point: 455 ° C.)
Except for baking at 00 ° C., a heater with a current blocking function was produced in the same manner as in Examples 2 to 4. Three heaters were manufactured by changing the film thickness of the overcoat layer 17, and the same evaluation was performed as described above. The results are shown in Table 1.

Comparative Examples 1 to 4 Comparative Examples 1 to 4 were the same as Example 1 except that the protective layer 16 and the overcoat layer 17 were sequentially laminated on the resistor pattern 14 without using the masking for forming the blocking portion 15. A heater was produced in the same manner (see FIG. 13). Four heaters were manufactured with the thickness of the overcoat layer 17 changed, and the same evaluation was performed as described above. The results are shown in Table 1.

Effects of Embodiments Embodiments 1 to 7 are examples in which a heater is provided with a cut-off portion which becomes an insulator by reacting with a component forming a resistor pattern. Since the softening point was lower than that of the glass component constituting the protective layer, the heater was broken only at the cutoff portion within 20 seconds in each case. At the time of destruction, the melted glass was allowed to cool and harden instantaneously without bursting of the break. The withstand voltage between the resistor after breakdown and the surface of the overcoat is also 0.65 to 1.9.
It was as high as 0 kV and the insulation was good. Although Pb-based glass and Bi-based glass were used as components constituting the blocking portion, when a Bi-based glass having a low transition point and a softening point was used, it was possible to break until the breakdown regardless of the thickness of the overcoat layer. Time got faster.

On the other hand, Comparative Examples 1 to 4 are examples in which the above-mentioned interrupting portions are not formed, and the breaking positions are various places in the resistor pattern, for example, the extraction electrode portion 13.
On the resistor pattern near a or 13b, the intermediate point between the extraction electrode portions 13a and 13b is irregular, and the time until breakdown is as long as 26 to 30 seconds. The withstand voltage between the resistor after breakdown and the overcoat surface Was as low as 0.3 to 0.65 kV, and the insulation was inferior.

The present invention is not limited to the above embodiment, but may be variously modified within the scope of the present invention in accordance with the purpose and application. That is, as the form of the heater, in addition to those shown in the above embodiments,
For example, the following mode can be adopted.

(1) As shown in FIG. 5, a second overcoat layer 18 for further covering the overcoat layer 17 and the blocking portion 15 of the heater (FIG. 2) manufactured in Example 1
Can be provided. (2) As shown in FIG. 6, the overcoat layer 17 and the blocking portion 15 of the heater (FIG. 4) manufactured in Example 2
May be provided. In the above cases (1) and (2), the second overcoat layer can be the same as that described for the overcoat layer. When the second overcoat layer is provided, the surface of the heater is further smoothed.

(3) As shown in FIGS. 7 to 12, the resistor pattern 14 and the cutoff portion 15 may not be in direct contact. In this case, it is preferable that the distance between the resistor pattern 14 and the cutoff portion 15 as viewed in the cross-sectional direction is short, and is usually 25 μm or less, preferably 20 μm or less, more preferably 15 μm.
It is as follows. If the thickness exceeds 25 μm, the reaction between the components constituting the resistor pattern and the components constituting the cutoff portion may not easily occur when the temperature is abnormally increased. Also, FIG.
The second overcoat layer 18 in FIGS. 10 and 12 can be the same as described above.

[0027]

According to the heater with the power cutoff function of the present invention, the heater operates abnormally and cuts off the power supply itself when the temperature exceeds a predetermined temperature without providing a new device such as a temperature control device or a temperature fuse. be able to. Also, there is no danger of smoke and ignition even when the power supply is cut off. When the temperature rises abnormally, the cut-off section provided above the resistor pattern, which is a heater element, reacts with the components that make up the resistor pattern to become an insulator, and the current is cut off. Since it does not cause any effect, the effect on the parts around the heater is small. When stainless steel is used as a material forming the substrate, the substrate does not crack due to abnormal temperature rise. Also,
After the reaction, the surface of the blocking part after the reaction (for example, glass) constituting the blocking part is melted and solidified, so that the work of replacing the heater can be performed safely. Furthermore, by properly selecting the components constituting the shut-off section, an abnormal value can be set according to the application, and the device can be used safely at a temperature within the standard.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a heater with a power cutoff function used in Example 1.

FIG. 2 is an explanatory cross-sectional view of a heater with a power cutoff function used in Example 1.

FIG. 3 is an explanatory schematic diagram of a heater performance test.

FIG. 4 is an explanatory cross-sectional view of a heater with a power cutoff function used in Examples 2 to 7.

FIG. 5 is an explanatory sectional view of a heater with an energization shut-off function according to another embodiment of the present invention.

FIG. 6 is an explanatory sectional view of a heater with an energization shut-off function according to another embodiment of the present invention.

FIG. 7 is an explanatory cross-sectional view of a heater with a power cutoff function according to another embodiment of the present invention.

FIG. 8 is an explanatory cross-sectional view of a heater with an energization cutoff function showing another embodiment of the present invention.

FIG. 9 is an explanatory sectional view of a heater with an energization shut-off function according to another embodiment of the present invention.

FIG. 10 is an explanatory cross-sectional view of a heater with an energization cutoff function showing another embodiment of the present invention.

FIG. 11 is an explanatory sectional view of a heater with an energization shut-off function according to another embodiment of the present invention.

FIG. 12 is an explanatory cross-sectional view of a heater with a power cutoff function according to another embodiment of the present invention.

FIG. 13 is an explanatory sectional view of a heater with an energization cutoff function used in Comparative Examples 1 to 4.

DESCRIPTION OF THE SYMBOLS 1: Heater with power cutoff function, 11; Substrate, 12; Insulating layer, 13a and 13b; Extraction electrode part, 14; Resistor pattern, 15; Cutoff part, 16; Protective layer, 17; Overcoat Layer, 18; second overcoat layer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Mutsumi Maruta 969, Oaza, Koshiro-shi, Aichi Pref. Misuzu Kogyo Co., Ltd. Terms (reference) 2H033 AA24 AA42 BA30 BA38 BA39 3K034 AA10 AA20 AA34 BA05 BA15 BB02 BB06 BB14 DA08 HA10 JA10 3K058 AA12 AA94 AA95 BA18 CA12 CA23

Claims (9)

[Claims] A substrate made of a metal material or an inorganic material;
In a heater including an insulating layer formed on the substrate and a resistor pattern formed on the insulating layer, at least a part of the resistor pattern that generates heat has a predetermined temperature. A heater having an energization interruption function, wherein an interruption part for reacting with a component constituting the resistor pattern to become an insulator and interrupting energization is formed. 2. The heater according to claim 1, further comprising a protective layer on the resistor pattern. 3. The component constituting the blocking part and the protective layer is glass, and the glass forming the blocking part has a lower softening point than the glass forming the protective layer.
A heater with an energization cutoff function described in 1. 4. The current blocking function according to claim 2, wherein the glass forming the blocking portion is a Pb-based glass and / or a Bi-based glass, and the glass forming the protective layer is a Si-based glass. With heater. 5. The heater according to claim 1, wherein the resistor pattern is made of a component containing silver. 6. The heater according to claim 1, wherein the metal material forming the substrate is stainless steel. 7. The heater according to claim 1, wherein the stainless steel is a heat-resistant ferritic steel. 8. The heater according to claim 1, wherein the insulating layer is made of glass. 9. The heater according to claim 2, further comprising an overcoat layer on the protective layer.