US1888670A

US1888670A - Self-insulated discharge tube terminal

Info

Publication number: US1888670A
Application number: US495648A
Authority: US
Inventors: Hotchner Fred
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-11-14
Filing date: 1930-11-14
Publication date: 1932-11-22
Anticipated expiration: 1949-11-22

Description

Patented Nov. 22, 1932 FRED HOTCHNER, OF LOS ANGELES, CALIFORNIA SELF-INSULATED DISCHARGE TUBE TERMINAL Application Med November 14, 1930. Serial No. 495,648.

- This invention relates to self-insulated discharge tube terminals, the object thereof being to provide a terminal for discharge tubes such as, for instance, luminous posltive column discharge tubes in the form of inscriptions as used in electric signs, which terminal need have no insulation other than that pro vided by its own construction at the place where it passes through the sign body.

In general, this invention pertains to any type of discharge tube which is to be insulated as against some outside element of the device in which it is installed, The insulation of discharge tubes for display Work is an extremely diiicult matter and at the present time a great source of annoyance and expense, also imposing certain limitations upon the construction of the apparatus, which are very undesirable.

It is to be borne in mind in the case of this illustration of the invention that rather high voltages are used and high frequencies sometimes are present due to characteristics of the circuit. Corona discharges tend to form and break down any insulation used at the terminal. In sign work, this is aggravated by the presence of accumulated dirt and moisture. A strict limitation is placed by the conditions .0f the Work upon the material which may be used for insulation in the prior art, such materials as rubber being excluded, and materials of the character of porcelain and glass being required.

The problem of insulating terminals of discharge tubes for sign Work has been and still is a source of great annoyance. It has been found that, considered the country over, weather conditions have caused the discarding of practically all types of insulating terminals excepting the open housing type, that is, the end of the tube extends into the orcelain housing which extends backward into the body of the sign, the housing being open to the weather and of such size that water will run out. This is an extreme construction from the early attempts at insulation which by various devices closed the housing to the weather by rubber gaskets, porcelain caps, or the like. 5 The use of the present type of housing is tends which is frequently out of proportion very objectionable in the art as they are awkward to install and unsightly and furthermore do not fully accomplish the purpose for which they are intended.

The necessity of providing a Wide opening in the housing makes it essential to observe a minimum dimension for the Width of the sign letters through which the housing exto the size of the letters. Hence a great many signs are made with the tubing formed to bend sideways and pass into the sign through housings installed through the main body ben side the letters, an obvious makeshift and expensive construction, but one which nevertheless must be followed in a good percentage of cases if the tube is to be properly insulated.

The present invention eliminates the necessity for large housings and permits the construction of signs with practically no limitation in the lay-out of the copy or construction of the letters so far as housings are concerned. Due to the fact that the tendency to form corona discharges is overcome at tlie point the terminal enters the body of the sign, rubber gaskets may be used in connection with this type of terminal without fear of disintegration of the rubber by the discharge, thus providing for the construction of water-tight signs.

The objects of the invention therefore, are to provide a discharge tube terminal which is provided with insulation Within the tube, which is proof against breakdown through the tube at the place the tube passes through a supporting body, which is free from corona action, and which can be installed in direct contact with the supporting body to effect a Water tight construction.

A further object of the invention is to reduce the cost of the terminal construction in the sign. Other objects Will be apparent from the following speciication and claims.

The invention is not limited to devices of the particular type illustrated but may be vvariously embodied in different types of discharge tubes and thus it is to be understood as being limited only by the prior art and I l the limitations specifically imposed by the vas a shield.

Numeral 1 in Fig. 1 indicates a typical discharge tube terminal of the type used herein as an illustration of the invention, 2 belng the portion which extends into the sign body making contact with the terminal sprlng 3 supported from an insulating post 4 wh1ch is fastened to the inside 5 of the sign face 6. The electrode 7 is of an internal type and is supported from the re-entrant stem 8, the lead-in conductor 9 extending through the stem and ending in the metallic contact 10 which contacts with the spring 3. The insulation is here provided by a conducting shield 11, which extends within the tube between two limits selected a material distance away Jfrom the plane of the sign face 6. Each end of this shield is provided with beads 1.2, 12, etc., as shown in the perspective view 1n Fig. 2, which spaces the shield a very little distance away from the inside wall 13 of the tube. The beads may be fused to the shield 11 in a manner well known in the art. The shield is positioned lengthwise in the tube by the offset shoulders 50 and 51. The space 14. between the outside surface 15 of the shield and inside surface 13 of the tube is made comparable to the length of the mean free path of the atoms of the contained gas within the tube. By comparable is meant slightly greater, the same, or less, in length, inasmuch as the phrase length of the mean free path is a somewhat uncertain quantity, the criteria here being that 'this dimension being reduced to a point at which a d1scharge cannot occur from the surface 15 of the shield 11 through the wall of the tube to the sign face 6. As is well known in the In the variation of the invention shown in Fig. 3, two shields are used, numbered 17 and 18, the shield 17 being provided with the

beads

19, 19, etc. in the same manner as in the illustration above, the shield 1.8 having flared

portions

20 and 21 which also terminate in beads 22, 22, etc. There are beads placed at the ends 23 and 24 of the shield 17 to space the same lengthwise with respect to the shield 18. In this view, the electrode is indicated by 25, the reentrance stem by 26, the lead-in wire by 27 and the terminal by 23. The object of this variation of the invention is to provide additional insulation to that provided by the single annular space shown in Fig. 1, by the insulating e'tect of the space 29 and also to take the potential oil' of the shield 17, thereby relieving the space 30 from the duty of resisting the potential from the terminal to ground.

A further variation of the invention is shown `in Fig. 4, in which an electrode 31 is shown made on the principle disclosed in several of my previously filed patent applications. such as Serial No. 302,473, which has resulted in Patent No. 1,789,901, and which provides for the construction of an electrode oextremely small dimensions capable of carrymg the load of very large electrodes of the prior art. In this view, 32 is a wall of the tube and it will here be seen that this has been greatly reduced in cross section as compared with the discharge tube proper 33, utilizing the characteristics of this particular electrode and of the instant invention. The end 34 of the electrode is positioned from the walls of the tube by the

beads

35, 35, etc., as is shown above, or obviously by any other suitable method so as to provide a space 36 of such small width that a discharge may not form between the outside wall 37 and the inside wall 38 of the tube 32.

As a further variation I illustrate a rubber ring 39, which in this invention, may be used without danger, because even though the rubber may deteriorate and become conduct-v ing, it cannot cause breakdown. It will also be seen that in the variation in Fig. 4, I have provided a construction far in advance of anything known in the prior art, of extreme practicability and simplicity, and one which completely solves the need for an insulating positive column discharge tube for sign work as well as in numerous other instances inthe discharge tube art.

Having thus described a particular embodiment of my invention as an illustratio thereof, what I claim is:

1. The combination of a metallic supporting member for a discharge tube, a hole therethrough, through which extends a terminal of said discharge tube, the diameter of said hole as compared with the diameter of the l'tube being such that additional insulation is necessary other than that of the wall of the tube itself, a shield within said tube extending both ways from the plane of said supporting member, the distance between the outside surface of said shield and the inside surface of said tube being so small that the insulating effect of a small space in the containing gaseous medium in such discharge tube provides the additional insulation needed.

2. In a discharge tube, a shield of conducting material within said tube parallelly disposed to and spaced a distance from the inside wall of said tube so small that the gaseous medium therebetween may not become conducting under normal operating conditions, and an additonalshield of conducting material within said irst shield parallelly disposed to and spaced a distance therefrom so small that the gaseous medium therebetween may not become conducting under normal operating conditions.

3. In an electric display` a metallic sign body, a discharge tube positioned on said sign body, said discharge tube having a terminal extending into said body, said terminal being provided with an insulating body of gas within said tube at the place where said tube enters said sign body.

4. In an electric display, a metallic sign' body, a discharge tube positioned on said sign body. said discharge tube having a terminal extending into said body, said terminal being provided with an insulating body of gas within-said tube at the place where said tube enters said sign body; the opening in said sign body through which said terminals ex tends being slightly greater in diameter than the outside diameter of said terminal, and a closure of yieldable material closing the opening between said terminal and the material of said sign body.

5. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends through a conductive portion thereof, means for preventing breakdown discharge from the interior of the tube to said portion comprising shielding means within said tube, and extending on opposite sides of said portion.

6. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends through a. conductive portion thereof, means 'ier preventing breakdown discharge trom the interior of the tube to said portion comprising shielding means within said tube.

'2'. In gaseous conduction tube mounting wherein the tube is mounted upon a support and extends through a conductive portion thereof, means for preventing break down discharge from the interior of the tube to said portion comprising shielding means within said tube, including a sleeve within said tube opposite said portion.

8. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends through a conductive portion thereof, means for preventin breakdown discharge from the interior o? the tube to said portion comprising shielding means within said tube, including a sleeve within said tube opposite said portion and spaced from the Wall of said tube.

9. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends through a conductive portion thereof, means for preventing breakdown discharge from the interior of the tube to said portion, comprising means substantially preventing ionization of the gas immediately adjacent the wall of said tube for a substantial distance along the tube on both sides of said portion.

10. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends through a conductive portion thereof, means for preventing breakdown from the interior of the tube to said portion consisting of an internal electrode positioned opposite said portion and extending a distance on each side thereof, the outer surface of said electrode being positioned so close to the inner wall of said tube that the gaseous medium remaining in the space therebetween is incapable of conducting by virtue of the insulating eifect of very thin layers of gas.

l1. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends through a conductive portion thereof, means for preventing breakdown from the interior of said tube to said portion consisting of an internal electrode positioned opposite said portion and extending a distance on each side thereof, the outside diameter of said electrode being slightly less than the inside diameter of said tube at said portion, and means to position said electrode in said tube so that a very small space remains therebetween ot such small thickness that the gaseous medium therein is nonconducting.

Signed at llos Angeles, California, this 10th day of November, 1930.

FRED HGTCHNER.