US3915899A - Resistors for ignition plugs - Google Patents

Abstract

Resistors comprising 4 to 20% by weight aluminum phosphate, 72 to 95% by weight tin oxide and 0.8 to 9.6% by weight antimony oxide. Such resistors are produced by adding low melting-point glass to the resistor components so that the latter can be made to stick together and harden into coherent solid bodies.

Description

[ Oct. 28, 1975 References Cited UNITED STATES PATENTS Heischman 252/516 252/512 Primary ExaminerBenjamin R. Padgett Assistant Examiner-E. Suzanne Parr Attorney, Agent, or Firm-Cushman, Darby & Cushman [57] ABSTRACT Resistors comprising 4 to 20% by weight aluminum phosphate, 72 to 95% by weight tin oxide and 0.8 to

9.6% by weight antimony oxide. Such resistors are produced by adding low melting-point glass to the resistor components so that the latter can be made to stick together and harden into coherent solid bodies.

5 Claims, 8 Drawing Figures iooooeb vv 2 i @wwwwww United States Patent [191 to et al.

Kam

igai

[ 1 RESISTORS FOR IGNITION PLUGS [75] Inventors: Osami Kamigaito; Hideyuki Masaki;

Masami Oki, all of Nagoya; Masatosi Suzuki, Kariya; Yasuo Nakamura, Nagoya, all of Japan [73] Assignees: Nippondenso Co., Ltd.; Dabushiki [30] Foreign Application Priority Data Nov. 17, 1972 [52] US. Cl. 252/518; 106/46; 338/66 [51] Int. H01B 1/08 [58] Field of Search 252/506, 518; 106/46;

US. Patent Oct.28, 1975 Sheet 1 of7 3,915,899

FIG.

*- PROPORTIONHN WEIGHT%)OF ANTIMONY OXIDE IN Tl-E BINARY REAISTOR COMPOSITIONS U.S. Patent Oct. 28, 1975 Sheet 2 of7 3,915,899

FIG.2

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I x l I I I I I I I TI-E VALLES OF RESlSTIV|TY(KQ-CM)OF BINARY RESISTIR COMPOSITIONS COMPRISING TIN OXIDE AND ANT IMONY OXIDE IN VARYING PROPORTION ,0

lb 20 3b 4b 5b PROPORTIONIIN WEIGHT% )OF ANTIMONY OXIDE IN THE BINARY REAISTOR coMPos|T|oNs US. Patent Oct. 28,1975 Sheet50f7 3,915,899

-5 -m -B -m -m -2 -m 8 6 4 -2 m m w w m m a a m z o i 5 B 30 9. C555. 5 mw ME m w a w m m m m 8 4 PROPORTION (IN OF ALUMINUM PHOSPHATE IN THE RESISTORS US Patent Oct.28, 1975 Sheet70f7 3,915,899

F I G. 7

RESISTORS FOR IGNITION PLUGS This invention relates to resistors, and more particularly it is concerned with resistors for ignition plugs whose resistance values are in a range from 3 to 20 k so that they do not disturb the reception of radio and other communication signals.

H'eretofore, the use of ignition plugs of low center electrode resistance values have been popular. However, ignition plugs of this type have the disadvantage of disturbing the reception of radio and other communication signals by producing electromagnetic waves when sparks are produced. Advances made in the progress of communication facilities have in recent years given rise to a cry for the need to control production of interfering electromagnetic waves. To cope with the situation, proposals have been made to insert a resistor in the electric circuit of an ignition plug for an internal combustion engine. Several systems have been proposed for inserting a resistor, and they may be broadly grouped into two systems or the system of inserting a resistor in the interior of the ignition plug and the system of mounting one in aih'i'gh'voltage wire of the ignition circuit.

In order to eliminate disturbance of the reception of communication signals, it is required that a resistor should have a resistance value which is in a range from 3 to k0 both at normal temperature and when heated and its temperature is raised up to 400C.

Since ignition plugs must be capable of resisting heat and withstanding high voltages, ignition plugs which have hitherto been favored are those of the conduci tively sealed type in which particles of electrically conductive materials are caused to stick together and harden into a coherent solid body by using heat resistant low melting-point glass. 3

In resistors for ignition plugs of the conductively glass sealed type, resistor components, such as metallic particles (copper, iron, nickel or nickel-chromium alloys), particles of carbon and the likeior particles of metallic oxides of low resistance (zinc oxide, barium oxide, trichromium dioxide, nickel oxide and the like) are added with glass particles of low melting point, such as borosilicate glass, and the mixture is heated to a temperature above the melting point of the glass so that the electrode may be sealed by adhesion force and the glass sealed body may serve as a resistor.

Some disadvantages are associated with the resistors of this type for ignition plugs produced as aforementioned. They are low in resistance value, with their resistivity values being below 0.01 kIl-cm. Such resistors of low resistance values are not effective in preventing noise production even if they are inserted in ignition plugs, because their resistance values are below 0.1 kQ. The resistance values of the resistors may be increased if the proportion of glass is increased. However, a slight change in the proportion of glass causes a great change in the values of resistivity of the resistors as from 0.01 to 1,000 kQ-cm to take place. Thus such resistors do not lend themselves to production on a commercial basis. Also, resistors of increased resistance values for ignition plugs which might be produced by increasing the proportion of glass in the resistors would be of little practical value because they are structurally unstable with the resistor components being scattered in the glass.

This invention has as its object the provision of resistors for ignition plugs made of novel resistor compositions so that the resistors have high resistance values ranging from 3 to 20 k0 and are highly effective in preventing noise production.

According to the invention, there are provided resistors for ignition plugs comprising 4 to 20% by weight aluminum phosphate, .72 to 95% by weight tin oxide and 0.8 to 9.6% by weight antimony oxide, such resistor components being added with low meltingpoint glass so that the former can be made to stick together and harden into coherent solid bodies.

FIG. 1 to FIG. 6 are diagrams illustrating the results of experiments,

FIG. 1 showing changes (in percent) in resistance value in relation to the proportion of antimony oxide before and after sparking of binary resistor compositions comprising tin oxide and antimony oxide in varying proportion and added with glass to cause them to stick together and harden;

FIG. 2 showing the resistivity values of binary resistor compositions comprising tin oxide and antimony oxide in varying proportion in relation to the proportion of antimony oxide in such resistor compositions;

FIG. 3 showing the resistivity values of the resistors according to the invention in relation to sparking time;

FIG. 4 showing the resistivity values of the resistors shown in FIG. 3 in relation to temperature;

FIG. 5 showing the values of resistance and resistivity of the resistors in relation to the proportion of aluminum phosphate in the resistor-composition;

FIG. 6 showing the resistivity values of the resistors in relation to the proportion of glass in the resistors;

FIG. 7 is a sectional front view of an ignition plug in which one of the resistors according to the invention is sealed; and

FIG. 8 is a sectional front view of an ignition plug in which another resistor according to the invention is arranged in the form of a rod.

The resistors for ignition plugs according to the invention comprise aluminum phosphate, tin oxide and antimony oxide which are made to stick together by adding low melting-point glass thereto. In the invention, aluminum ortho phosphate is used as aluminum phosphate, tin monoxide or tin dioxide as tin oxide and antimony trioxide as antimony oxide. Borosilicate glass is used as low melting-point glass.

Production of such-resistors will be described by way of example with reference to FIG. 7 and FIG. 8. 99% by weight tin dioxide and 1% by weight antimony trioxide are mixed and made to react with each other in an alumina crucible at 1,100C for 5 hours. Then the mixture is cooled to normal temperature, and by weight of the mixture and 10% by weight aluminum phosphate are mixed well and made to react with each other at 1,100C for 5 hours. 50% by weight of this ternary resistor composition in particulate form and 50% by weight low melting-point glass in powder form consisting mainly of a borosilicate are mixed, and about 1% by weight of an organic binder is added to the mixture. The mixture produced is granulated and filled in a predetermined amount in an axial bore formed in an insulator 4 above a center electrode 3 as shown in FIG. 7. Then an inner shaft 1 is inserted in the axial bore from above and heated at 850C for 30 minutes. Thereafter pressure is applied to the inner shaft 1 so that the granulated mixture may be sealed in the axial bore by heat and pressure. After the mixture is fixed and cooled, it serves as a resistor 2. is a housing, and 6 a grounded electrode.

The resistor produced as aforementioned and interposed between the center electrode 3 and inner shaft 1 performs not only the function of preventing disturbance of the reception of communication signals but also the functions of securing the center electrode and inner shaft to the insulator 4 in airtight relationship. Such resistor has been found to have a resistance value of6 kfl at normal temperature and 5.4 k!) when heated to 400C. Tests conducted on airtightness show that the resistor is free from leak even under a pressure of 30 kg/cm The ignition plug having the resistor 2 was attached to a motor vehicle engine and tested. The results show the provision of the resistor is effective in minimizing noise production which might otherwise occur when a conventional ignition plug having no resistor is employed.

In FIG. 8, another resistor according to the invention is arranged in the form of a rod-shaped solid in the axial bore of the insulator. The center electrode 3 inserted in the lower end portion of the axial bore of the insulator 4 is sealed by a conventional highly conductive material 7. A metallic conductor 9 is secured to the upper portion of the material 7, and a spring 8 is mounted on the metallic conductor 9. The resistor 2 according to the invention is interposed between the spring 8 and inner shaft 1'. The inner shaft 1' is threaded into the axial bore of the insulator 4 to hold the resistor 2 in place. Thus the resistor 2' arranged as aforementioned need not perform the function of securing the electrode 3 and inner shaft 1 to the insulator 4 in airtight relationship as is the case with the resistor 2 shown in FIG. 7.

The aforementioned resistors comprise 50% of a ternary resistor composition comprising 89.1% tin dioxide, 0.9% antimony trioxide and 10% aluminum phosphate, and 50% of glass.

As aforementioned, the resistors according to the invention comprise 4 to by weight aluminum phosphate, 72 to 95% by weight tin oxide and 0.8 to 9.6% by weight antimony oxide, such resistor components being sintered (made to stick together and harden) by adding low melting point glass thereto. The reasons why the aforementioned range of components is adopted in the invention will now be described.

First of all, in order that any ignition plug may be stable in performance or changes in resistance shown by the resistor in the ignition plug may be minimized in spite of repeated sparking, it is required that tin oxide and antimony oxide should be in a predetermined proportion to each other. Stated differently, when tin oxide is 90 to 99% by weight, antimony oxide should be 10 to 1% by weight. It has been found that, when antimony oxide is below 1%, the resistor is unstable in performance. When it is above 1%, the resistor is highly stable in performance. However, when it is above 10%, air bubbles are formed and tend to invade the glass phase when the resistor components are made to stick together and harden by adding glass to them, thereby producing a resistor unfit for practical use.

When the resistors are composed of these two components only or they are of the binary resistor system, their resistivity values are rather low, being in a range from 10 to 10 kQ-cm. Thus the resistors produced are not satisfactory for specifications. This makes it necessary to add aluminum phosphate as a third component to the binary resistor compositions. According to the invention, aluminum phosphate is added in an amount such that, when the mixture of tin oxide and antimony oxide is to 96% by weight. aluminum phosphate is 20 to 4% by weight. It has been found that, when aluminum phosphate is below 4%, it is not possible to produce a resistor having a resistance value of over 3 kQ when used with an ignition plug of a size fit for practical use, and that, when aluminum oxide is above 20%, it is not possible to produce a resistor having a resistance value below 20 k0. It will be appreciated that the resistors according to the invention comprise 4 to 20% by weight aluminum phosphate, 72 to 95% by weight tin oxide and 0.8 to 9.6% by weight antimony oxide.

In the embodiment described above, the ratio of the low melting-point glass to the ternary resistor composition was 50 50. It is to be understood that the invention is not limited to this proportion of glass to ternary resistor composition and that the proportion may be varied. Preferably, the ratio of the resistor composition to the low melting-point glass is 40 60 to 10. It has been found that, when the glass is over 60 it invades particles of the resistor composition and increases the resistance values of the resistor. Also, a slight change in the amount of glass in relation to that ofa resistor composition results in a great change in the resistance value of the resistor, thereby making it difficult to produce resistors of desired resistance values (See FIG. 6). The glass is preferably over 10% so as to be able to satisfactorily cause particles of the resistor composition to stick together. When the resistor is sealed in the ignition plug as shown in FIG. 7, it is desirable that the glass should be over 20% in order that the ignition plug may be kept airtight.

Any resistor according to the invention can be used with an ignition plug by arranging it in one of three different positions: inserted in the ignition plug and sealed in between the center electrode and inner shaft; inserted in the ignition plug in the form of a solid body; and mounted in a high voltage wire of the ignition circuit outside the ignition plug.

When a resistor is inserted in an ignition plug, the resistor is sealed in, as described previously with reference to FIG. 7, between the center electrode 3 and the inner shaft 1 by adhesion force so that they are connected together. The resistor thus performs not only the function of preventing disturbance of the reception of communication signals but also the functions of passing a current between the electrode 3 and the center shaft 1 and securing them to the insulator 4 in airtight relationship. When a resistor is inserted in the form of a solid body in an ignition plug, the resistor is interposed between the spring 8 and the inner shaft 1 as described with reference to FIG. 8. The resistor thus need not perform the function of airtight sealing.

As aforementioned, the present invention provides resistors comprising three resistor components or aluminum phosphate, tin oxide and antimony oxide and produced by adding low melting-point glass to the resistor components so that the latter can be made to stick together and harden into coherent solid bodies. In producing such resistors, tin oxide and antimony oxide are first mixed together and heated to elevated temperature to cause them to react with each other. Aluminum phosphate is then added to the mixture and heated to elevated temperature again so that they may react with each other and may be shaped into minuscule particulate form. Borosilicate glass or other low melting-point glass is added to the ternary resistor composition in minuscule particulate form, and then polyvinyl alcohol or other binder is added to the mixture. The mixture is thoroughly mixed so that it may be rendered homogeneous.

The mixture is filled in an ignition plug or mold and heated to elevated temperature to soften the glass, and then cooled to provide a coherent solid body which is used as a resistor. When the mixture is filled in the ignition plug, it is filled between the center electrode 3 and inner shaft 1 as shown in FIG. 7 as is the case with a conventional sealed resistor. Then pressure is applied to the inner shaft so as to bond the resistor to the center electrode and inner shaft by adhesion force, thereby producing an ignition plug including the resistor 2 interposed between the inner shaft 1 and center electrode 3 as shown in FIG. 7. The mixture filled in a cylindrical mold or other mold is subjected to successive heating and cooling. Thus a rod-like resistor of columnar or other shape is produced. This resistor is inserted between the conductor 9 electrically connected to the center electrode 3' and inner shaft 1' as indicated at 2' in FIG. 8.

Experiments were carried out on the proportion of resistor components to one another in the resistors and the proportion of resistor compositions to glass in the resistors. The results of the experiments will be described hereinafter. In the experiments, the tin oxide, antimony oxide and aluminum phosphate used were in the form of SnO Sb- O and MP0, respectively, and the low melting-point glass used was borosilicate glass. As described in each example, each resistor was produced by mixing each resistor composition with the aforementioned glass so that the resistor components may be made to stick together and harden by the action of the glass.

EXPERIMENT 1 FIG. 1 shows the results of experiments conducted on the stability of resistor compositions of the binary system comprising tin oxide and antimony oxide. Binary resistor compositions comprising tin oxide and antimony oxide in varying proportion were sintered by using low melting-point glass to provide binary resistors of rod-shape. The binary resistors were each inserted in the form of a solid body in an ignition plug and tested by the method of testing the life of loaded resistors of JIS D5102.

In FIG. 1, there are shown the results of tests carried out to find out changes (in percent) in the values of resistance of the aforementioned binary resistors before sparking and after sparking for 250 hours. The changes in the values of resistance (in percent) are plotted as the ordinates against the proportion of antimony oxide in the binary resistors comprising tin oxide and antimony oxide as the abscissae.

It will be seen in FIG. 1 that, when antimony oxide was below 1%, the changes in the values of resistance before and after sparking were very great, so that such resistors would be unfit for practical use. On the other hand, it will be evident that, when antimony oxide was above 1%, the changes were very small, and that, particularly when antimony oxide was above 2%, there was almost no change in the values of resistance and thus the resistors proved to be highly stable in performance.

However, it should be noted that, when antimony oxide exceeded 10%, an increasingly large proportion of the resistor components melted into the glass and the air bubbles formed in the glass tended to remain therein. Thus the glass was brought to a foaming state, thereby rendering the resistors unfit for practical use.

FIG. 2 shows the values of resistivity of binary resistor compositions produced by causing tin oxide to react with antimony oxide. The values of resistivity (kQ-cm) are plotted as the ordinates against the proportion of antimony oxide as the abscissae in FIG. 2 in which the ordinates are in a logarithmic scale and the abscissae are in a uniform scale. It will be seen in FIG. 2 that, when the proportion of antimony oxide in the resistor compositions was below 10%, the values of resistivity of the resistors made of binary resistor compositions comprising tin oxide and antimony oxide were low or below 0.00007 kQ-cm.

It has been ascertained that, by adding a third resistor component or aluminum phosphate to the aforementioned binary resistor compositions comprising tin oxide and antimony oxide, it is possible to increase the values of resistivity 10 to 10 times. The stability of ternary resistor compositions comprising aluminum phosphate added to the binary resistor compositions comprising tin oxide and antimony oxide will be described with reference to FIG. 3 and FIG. 4.

FIG. 2 shows the results of tests carried out on two types of resistors produced by mixing the aforementioned ternary resistor compositions comprising tin oxide, antimony oxide and aluminum phosphate with borosilicate glass in equal proportion by the method of testing the life of loaded motor vehicle ignition plugs having resistors of JIS D5102. The method consists in determining the values of resistivity (kO-cm) of the resistors after causing the same to spark for a predetermined time interval. In FIG. 3, the values of resistivity are plotted as the ordinates against time in hours in which sparking was effected as the abscissae. In the figure, a line a represents the value of resistivity of one type of resistors made of a ternary resistor composition comprising 98.1% by weight tin oxide, 0.9% by weight antimony oxide and 10% by weight aluminum phosphate, and a line b represents the value of resistivity of the other type of resistors made of a ternary resistor composition comprising 81% by weight tin oxide, 9% by weight antimony oxide and 10% by weight aluminum phosphate. Both the ordinates and the abscissae in a logarithmic scale. As can be clearly seen in FIG. 3, the values of resistivity of the two types of resistors show no change in spite of prolonged sparking, indicating that they are superb resistors.

FIG. 4 shows the results of tests carried out on the aforementioned two types of resistors made of the ternary resistor compositions by the method of heating motor vehicle ignition plugs having resistors of JIS D5102. In the figure, the values of resistivity (kQ-cm) are plotted as the ordinates against the temperature (C) of the resistors of JIS D5102, and lines a and b represent the values for the resistors of the same compositions as described with reference to the lines a and b in FIG. 3. The R in the figure indicates that the resistors are cooled to normal temperature after being heated to determine the values of resistivity. In the figure, the ordinates are in a logarithmic scale and the abscissae are in a uniform scale.

It will be seen in FIG. 4 that the resistors tested show little change in the values of resistivity even when heated to elevated temperatureflt is thus evident that the resistors made of ternary resistor compositions for ignition plugs according to the invention meet the requirement of JIS D5102 that the'values of resistance should be within i30% of the rated resistance value. The resistors used for the tests shown in FIG. 3 and FIG. 4 were of columnar shape and had the same size.

EXAMPLE 2 The values of resistance and resistivity of resistors made of ternary resistor compositions comprising aluminum phosphate as a third component will now be described with reference to FIG. 5 in which the values of resistance (1(0) and the corresponding values of resistivity (kQ-cm) of the resistors are plotted as the ordinates against the proportion of aluminum phosphate in the resistor compositions as the abscissae.

In FIG. 5, lines and d are followed by resistors comprising tin oxide and antimony oxide in varying proportions presently to be. described, with each line representing the values of resistance and resistivity of resistors made of ternary resistor compositions comprising the aforementioned two components in a predetermined proportion and third component or aluminum phosphate in varying proportion and made to stick together by adding low melting-point glass thereto. That is, theline c represents the values of resistance (and resistivity) of resistors for ignition plugs made of a binary resistor composition comprising 99% tin oxide and 1% antimony oxide added with aluminum phosphate in varying proportion and prepared by mixing 50% of ,each of such ternary resistors compositions with 50% of low melting-point glass. The line d represents the values of resistanceof resistors forignition plugs made of a ternary resistor composition comprising 90% tin oxide and 10% antimony oxide added with aluminum phosphate in varying proportion and prepared by mixing 50% of each of such ternary resistor compositions with 50% of low melting-point glass. All the resistors usedin this series of tests were of rod shape and had a length of 2.2 millimeters and a diameter of 3 millimeters.

. As can be seen in FIG. 5, the values of resistance increased proportionally as the proportion of aluminum phosphate in the resistor compositions increased, and

thatjthistendency was not affected by the differences in proportion between tin oxide and antimony oxide in the resistor compositions. The higher the proportion of tin oxide in the resistor compositions, the higher were the values of resistance of the resistors. As aforementioned, the line c in FIG. 5 represents the values of-resistance of resistors comprising'a binary resistor composition of 99% tin oxide and 1% antimony oxide and 1a. third component or aluminum phosphate added to the binary resistor composition in varying proportion. In this binary resistor composition, tin oxide exists'in its maximum proportion. It will be seen that the values of resistance'of the resistors were over 3 k0 when the proportion of aluminum phosphate added to the binary recomponent or aluminum phosphate'added to the binary resistor composition in varying proportion. It will be seen that the resistors have values of resistance of over 3 k0 whenthe proportion of aluminum phosphate was over about 10%. This indicates that,;if it isdesired to produce resistors of a resistance value of below20 k0, one has only to reduce the proportion of aluminum phosphate below about 20% in the resistorcompositions of lines 0 and d.

It will be seen that it is possibl'e'to produce -resistors having resistance values in a range from 3 to 20 k0 if the proportion of aluminum phosphate is adjusted to 4 to 20%, The values of resistance of the resistors according to the invention can be slightly varied by varying the ratio of the amount of a resistor composition to that of low melting-point glass added to the resistor composition as presently to be described with reference to FIG. 6.

EXAMPLE 3 point glass to a resistor composition is varied. In FIG.

6, the values of resistivity (kQ-cm) are plotted as the ordinates against the proportion of glass added to the resistor composition as the abscissae. The resistor composition used in this series of tests was made up of 85.5% tin oxide, 4.5% antimony oxide and 10% aluminum phosphate. Such ternary resistor composition and borosilicate glass were mixed with each other in varying proportion and heated to about 850C to produce rod-shaped -resistors. The resistors produced were tested for resistivity.

It will be seen that, when the proportion of glass exceeded the values of resistivitygreatly increased, and that no large change was shown when the-proportion of glass was below this level.

As aforementioned, the resistors for ignition plugs according to the invention are produced by sintering resistor compositions comprising 4 to 20% by weight aluminum phosphate, 72 to 95% by weight tin oxide and 0.8 to 9.6% by weight antimony oxide by adding low melting-point glass to the resistor components. The resistors provided by the invention have resistance values ranging from3 to 20 k0 which are necessary for preventing noise production. Particularly noteworthy is the fact that the invention permits the values of resistivity of binary resistor compositions comprising tin oxide and antimony oxide to be greatly increased from below 10 Q-cm to l00-10,000 Q-cm by adding a small proportion of aluminum phosphate as a third component to the binary resistor compositions. Thus the resistance values of the resistors according to the invention can be increased without requiring to take the trouble to increase the proportion of glass. This offers added advantages'in that the resistors show little variation in resistance 'value and their structural stability is high and that the values of resistivity of the resistors can be varied by adjusting the proportion of the aluminum phosphate added to the binary resistor compositions to a suitable level. The resistors are low in cost because the aluminum phosphate used'as the third component of the resistor is low in cost.

i What we claim is: i J

l. A'resistor consisting essentially of 40 to by weight of resistance materialand 10 to 60% by weight of low meltingglass, the resistance material comprising 4 to 20% by weight of aluminum orthophosphate, 72 to by weight of't in oxide selected from the group is 20 to by weight of the total of glass and resistance material.

4. A resistor according to claim 1, wherein the antimony oxide is 1 to 10% by weight of the total of tin oxide and antimony oxide.

5. A resistor according to claim 1 having a resistance of 3 to 20 kiloohms.

UNITED STATES PATENT ()FFICE CERTIFICATE OF CORRECTION Patent; N0, 899 Dat d October 28, 1975 Inventor(s) Osam'i Kamiqaito et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Item [73] change "Dabushiki Kaisha Toyota Chuo Kenkyosho" to read Kabushiki Kaisha Toyota Chuo Kenkyusho Signed and Scaled this thirtieth D ay 9f March I 9 76 [SEAL] Arrest:

RUTH c. MASON (nmmissimwr nfParents and Trademarks UNlTED STAQES PATENT OFFICE QERTIFICATE 6F CORRECTION Patent; No. 319151899 D t d October 28, 1975 Inventor(s) osami Kamiqaito et 6.1

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Item [73] change "Dabushiki Kaisha Toyota Chuo Kenkyosho" to read Kabushiki Kaisha Toyota Chuo Kenkyusho Signed and Sealed this thirtieth D f March 1976 [SEAL] A ttest:

RUTH C. M AnSON C. MARSHALL DANN AI H g fjlfl Commissioner ofiarents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF ZORRECTION Patent: No. 899 Dated October 28, 1975 Inventor(s) o i Kamiqaito et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Item I73] change "Dabushiki Kaisha Toyota Chuo Kenkyosho" to read Kabushiki Kaisha Toyota Chuo Kenkyusho Signed and Scaled this thirtieth D f March 1976 [SEAL] A ttest:

RUTH.C. M A SON C. MARSHALL DANN Arresting Ojjwer Commissioner oj'Parenrs and Trademarks

Claims (5)

1. A RESISTOR CONSISTING ESSENTIALLY OF 40 TO 90% BY WEIGHT OF RESISTANCE MATERIAL AND 10 TO 60% BY WEIGHT OF LOW MELTING GLASS, THE RESISTANCE MATERIAL COMPRISING 4 TO 20% BY WEIGHT OF ALUMINUM ORTHOPHOSPHATE, 72 TO 95% BY WEIGHT OF TIN OXIDE SELECTED FROM THE GROUP CONSISTING OF TIN MONOXIDE AND TIN DIOXIDE AND 0.8 TO 9.6% BY WEIGHT OF ANTIMONY TRIOXIDE, THE COMPONENTS OF SAID RESISTANCE MATERIAL BEING ADHERED TOGETHER AND HARDENED INTO A COHERENT SOLID BY SAID LOW MELTING GLASS.

2. A resistor according to claim 1, wherein the glass is a borosilicate glass.

3. A resistor according to claim 1, wherein the glass is 20 to 60% by weight of the total of glass and resistance material.

4. A resistor according to claim 1, wherein the antimony oxide is 1 to 10% by weight of the total of tin oxide and antimony oxide.

5. A resistor according to claim 1 having a resistance of 3 to 20 kiloohms.

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