US3617793A

US3617793A - Electrode mounting structure for providing insulation

Info

Publication number: US3617793A
Application number: US863043A
Authority: US
Inventors: Tokuo Matsushita; Satoshi Watanabe
Original assignee: Okaya Electric Industry Co Ltd
Current assignee: Okaya Electric Industry Co Ltd
Priority date: 1968-10-19
Filing date: 1969-10-02
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02

Abstract

An indicator discharge tube having an insulating mask in which a plurality of slits are formed with similar pattern to that of cathode electrodes disposed on an insulating baseplate, said insulating mask being arranged between said insulating baseplate and an anode electrode with a narrow gap from said insulating plate.

Description

United States Patent ELECTRODE MOUNTING STRUCTURE FOR PROVIDING INSULATION 3 Claims, 5 Drawing Figs.

U.S. Cl 313/109.5, 313/268, 313/205 Int. Cl 1101] l/90, H01 j 19/44 Field of Search 3 l 3/109.5, 268, 259

[56] References Cited UNITED STATES PATENTS 2,632,128 3/1953 Hancock 313/l09.5 X 3,278,779 10/1966 Szegho 313/259 X 3,281,619 10/1966 Greene 3l3/l09.5 X 3,346,759 10/1967 Hardwick 3 l 3/l09.5

Primary Examiner- Eli Lieberman Assistan! ExaminerWm. 1-1. Punter Attorney-Hill, Sherman, Meroni, Gross & Simpson ABSTRACT: An indicator discharge tube having an insulating mask in which a plurality of slits are formed with similar pattern to that of cathode electrodes disposed on an insulating baseplate, said insulating mask being arranged between said insulating baseplate and an anode electrode with a narrow gap from said insulating plate.

ELECTRODE MOUNTING STRUCTURE FOR PROVIDING INSULATION BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention relates to an indicator discharge tube, and more particularly to an indicator discharge tube to display numerals, characters or the like through the use of a plurality of electrodes arranged with a predetermined spaced relation with each other.

2. Description of the Prior Art In the prior art indicator discharge tubes, drawbacks have arisen that the metal making up the cathode electrodes is sputtered therefrom when the discharge tube is applied with discharge voltage and finally the sputtered cathode metal particles covers substantially the entire surface of the surface of an insulating baseplate between the adjacent cathode electrodes, which leads to short circuiting of the adjacent cathode electrodes to render them inoperative.

SUMMARY OF THE INVENTION Accordingly, the primary object of the present invention is to provide a novel indicator discharge tube which avoids the drawbacks such as short circuiting phenomena between the adjacent cathode electrodes caused by the so-called cathode sputtering."

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a conventional prior art indicator discharge tube;

FIG. 2 is an enlarged cross-sectional view of a prior art device taken along the line I-I in FIG. 1;

FIG. 3 is an enlarged cross-sectional view showing one example of this invention;

FIG. 4A is a front view illustrating an insulating baseplate used in the example depicted in FIG. 3; and

FIG. 4B is a front view illustrating an insulating mask employed in the example depicted in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Prior to a detailed description of the present invention, one example of conventional prior art indicator discharge tubes wiil be described in detail with reference to FIGS. 1 and 2.

A conventional indicator discharge tube is shown in FIGS. 1 and 2. In FIG. I, reference numeral 1 designates an airtight envelope made of a transparent glass and 2 a stem made of ceramic. Reference numeral 3 represents an insulating baseplate which has formed therein a plurality of grooves 4 arranged in a predetermined pattern, the predetermined pattern being number 8 in this example. Cathode electrodes 5 made of, for example, nickel, tantalum, stainless steel or the like are embedded in the grooves 4 respectively. In this case the cathode electrodes are embedded in a manner not to jut beyond the surface 3' of the baseplate 3. A gridlike or meshlike anode electrode 6 is disposed in opposing but spaced relation to the insulating baseplate 3. The gridlike or meshlike anode electrode 6 is fixedly supported at both side edges thereof with support frames 7 and at front and back surfaces thereof with shockproof mica plates 8 to thereby keep the relationship between the anode electrode 6 and the cathode electrodes 5. Lead wires 9 connected at one end thereof to the respective cathode electrodes 5 and the anode electrode 6 are led out to the back surface of the insulating baseplate 3 through apertures (not shown) bored therethrough and further led to the outside of the airtight envelope 1 through the stem 2 used to he leads for connecting the other ends to other electric circuit elements. The airtight envelope 1 is filled with an inert gas such as neon, argon or the like or a mixture of them at a pressure in the range of about several tens to 100 mm. of Hg. With such an arrangement, when the tube is subjected to discharge, the metal making up the cathode electrodes 5 is disposed on the surface portion 3 of the insulating baseplate 3 between and in the vicinity of the adjacent cathode electrodes 5 due to the sputtering as metal particles indicated at dots 10 in FIG. 2 and finally all the surface 3'. This sputtering phenomena cause in practical use such fatal defects as short circuiting of the adjacent cathode electrode 5 with the metal particles 10 on the surface 3' of the insulating baseplate 3 to bring the tube to be of no use.

In view of the foregoing drawbacks of the prior art, this invention is to provide an indicator discharge tube in which an insulating mask as show in FIG. 3 and 4B is inserted between an anode electrode and cathode electrodes.

With reference to FIGS. 3 and 4, a description will hereinafter be given of one example of the present invention in detail.

In FIGS. 3 and 4 similar elements to those in FIGS. 1 and 2 are identified by the similar reference numerals and are omitted the description thereof.

In this invention, an insulating mask 12 is disposed on the insulating baseplate 3 for respectively insulating the adjacent cathode electrodes 5. In this case the insulating mask 12 is disposed in such a manner that a narrow gap 11 is formed between the insulating mask 12 and the insulating baseplate 3. The anode electrode 6 is disposed in opposing but spaced relation to both the cathode electrodes 5 and the insulating mask 12.

Further, a description will hereinafter be given in detail on the example.

A plurality of shallow grooves 13 are fonned in the front surface of the insulating baseplate 3 enough to sufficiently hold the cathode electrodes 5 thereon. The insulating mask 12 is disposed on the insulating baseplate 3 through thin insulating spacers 14 made of mica or like material therebetween to respectively insulate the adjacent cathode electrodes 5. A plurality of slits or slots 15 are formed in the insulating mask 12 at places corresponding to the cathode electrodes 5 so that the cathode electrodes 5 can be seen through the slits 15 of the insulating mask 12. The anode electrode 6 is disposed in opposing and spaced relation to the insulating mask 12 at the outer side opposing to the baseplate 3 with respect to the insulating mask 12. The anode electrode 6 is gridlike or meshlike similar to that in FIG. 1 example. Lead wires (pot shown) for the cathode electrode and the anode electrode are respectively led out to the back of the insulating baseplate 3 from the cathode electrodes 5 and the anode electrode 6 through bores (not shown) formed in the insulating baseplate 3 and also through the stem 2 as in FIG. 1 example.

With such a construction, a discharge voltage is supplied across the cathode electrodes 5 and the anode electrode 6 to produce glow discharge. Due to the glow discharge, the metal making up the cathode electrodes is sputtered therefrom to the portions in the vicinity of the cathode electrodes 5, that is, the sputtered metal particles are deposited on the surface of the insulating baseplate 3 and the insulating mask 12 in the vicinity of the cathode electrodes 5 as indicated by dots 10, which is similar to that in FIG. 1 example. However, since in the present invention the narrow gap 11 having a distance 3 is formed between the insulating mask 12 and the distance g is selected narrow, for example, as 0.05 mm. to 0.l mm., the cathode metal particles do not sputter into the gap II remote from the opening thereof. That is, the sputtered cathode metal particles are not deposited on the entire surfaces of the insulating mask 12 and insulating baseplate 3 between the adjacent cathode electrodes. Consequently, the indicator discharge tubes according to the present invention has a longlife insulation between the cathode electrodes 5.

According to the present invention such an advantage as the trouble of the short circuiting between the cathode electrodes is prevented is attained.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

We claim as our invention:

mask being disposed in such a manner to provide a narrow gap between the insulating baseplate and the insulating mask.

2. An indicator discharge tube as claimed in claim 1, wherein a spacer is inserted between the insulating baseplate and the insulating mask.

3. An indicator discharge tube as claimed in claim 1, wherein the distance of the gap is selected to be the range of 0.05 mm. to 0.1 mm.

* I t l

Claims

1. An indicator discharge tube comprising an insulating baseplate having a plurality of grooves formed thereon in a predetermined pattern, a plurality of cathode electrodes disposed in the grooves of the insulating baseplate respectively, a single anode electrode disposed common to the plurality of cathode electrodes with a space, and an insulating mask insulating the plurality of cathode electrodes respectively having a plurality of slits substantially in similar patterns to that of the grooves formed in the insulating baseplate, the insulating mask being disposed in such a manner to provide a narrow gap between the insulating baseplate and the insulating mask.