US1950394A - Electrical operating device for neon and like signs - Google Patents

Description

March 13, 1934. c. P. BOUCHER 1,950,394

ELECTRICAL OPERATING DEVICE FOR NEON AND LIKE SIGNS Filed Dec. 14, 1951 2% 37 35 23 3a lj EH m /2 as I "1 --E i E Ht-{I 4 Ezzgm FFCS I.

FFG. a: L05 [0 AQQ/ 1'67 8- w, \W W HVVE/VTQR C W V Patented Mar. 13, 1934 PATENT OFFICE I ELECTRICAL OPERATING DEVICE FOR NEON AND LIKE SIGNS Charles Philippe Boueher, Montreal, Quebec,.

Canada,

assignor of one-half to Lindsay Carlton Mickles, Montreal, Quebec,

Canada.

Application December 14, 1931, Serial No. 580,793

9 Claims.

This invention relates to luminescent electric signs, such as neon'signsand more particularly to an electrical system and apparatus for the operation of the same.

One of the objects of my invention is to provide a simple, inexpensive, and thoroughly practical system and apparatus for the highly efiicient and reliable operation of luminescent gaseous conduction devices or gas-filled tubes, such as neon tubes, of various shapes and sizes comprising, for example, an electric sign.

Another object is to maintain maximum clear and brilliant operation of luminescent tubes or devices of the character indicated throughout long periods of continuous and uninterrupted use at maximum operating efiiciency, at minimum expense and with minimumdanger to life and property.

Another object is to assure uniform brilliancy of operation of various luminescent gas-filled tubes forming part of the same luminescent display, in spite of various inequalities and differences in the several tubes in matters of size, shape, the nature and pressure of the luminiferous gas used and like physical differences which affect the electrical characteristics of the tubes em- -ployed.

Other objects in part will be obvious and in part pointed out hereinafter.

The invention, accordingly, consists in the various combinations of elements, features of construction and arrangement of parts as described herein and shown in the accompanying drawing, and the scope of the application 'of which is indicated in the following claims.

Referring now to the drawing:

Figure 1 is a diagram of the electrical system and apparatus for operating a plurality of individual luminescent gas filled tubes comprising a single luminescent sign or display, and Figure 2 is an enlarged view of a luminescent tube shown in Figure 1 partially broken away to more clearly disclose certain features of construction.

As conducive to a clearer understanding of certain features of my invention it may be noted at this point that luminescent gaseous conduction devices or gas filled tubes of the class indicated vary onefrom another in the matter of electrical characteristics, particularly in the matter of electrical resistance, even where attempt is made in manufacture to produce identical tubes. Ordinarily the various tubes utilized in a single sign or display are of different shapes and lengths, conforming to certain designs or configurations ,the applied potential is ously affect the proportion of the so as to give a desired arrangement for a combined effect.-

It may be further noted that in the operation of luminescent gas filled tubes or devices of the character indicated from a source of alternating current electrical energy the instantaneous resistance of any one tube or device varies greatly from the time when the instantaneous value of insufficient to causean ionized condition of the containedgas (during which the tube is of high electrical resistance, is non-conductive and is non-luminous) and when the applied potential, in either the alternatively positive or negative portion of the cycle, has risen to such a value as to ionize the gas and thus cause the tube to become a good conductor of comparatively low resistance and luminescent. Where the ionized or conductive condition of the tube is established a substantial current flows through the tube (tending to quickly increase due to the decidedly negative resistance characteristics of such tubes) until the continuously changing applied potential has fallen to such a low value that the ionized condition of the tube may no longer be maintained. At this timev the tube again becomes non-conductive and non-luminous and remains so until the instantaneous value of the applied potential again rises, in following through the cycle of alterations, to apoint suflicient to again cause the gas to become ionized, conductive and luminous. Y

The proportion of the time of a complete cycle of alternations of the source of electrical energy that the gas filled tube is luminescent depends first upon the proportionate length of time that the tube is rendered conductive (the proportionate period between the time when the instantaneous potential becomes sufficient to ionize the gas contained in the tube and the time when this potential falls to such a value that the ionized condition may no longer be maintained) and second upon the proportion of this proportionate length of time that the current density within the conductive tube (influenced by other elements, such.

as capacitances, inductances and resistances in 00 the electrical circuit of the gas filled tube) is sufiicient to render the tube luminescent.

The various gas filled tubes employed in a single display are of different electrical characteristics, particularly in the matter of the ionizing potential, the potential at which ionization may not be maintainedfand the electrical conductance (or resistance) during the ionized condition. These characteristics, as indicated above, tend to varitime any one of the tubes of the entire display is luminescent as well as the degree or intensity of this luminescence.

Thus, one of the objects of my invention is to maintain the several gas filled tubes or devices of a luminous sign system uniformly brilliant and luminescent for substantially the same length of time in spite of inherently different electrical characteristics of the several tubes, as indicated above, as well as to increase the proportion of the time that the several gas filled tubes are rendered luminescent.

As more particularly indicated above, the resistance of any one of the gas filled tubes of a single system varies greatly from the unionized condition of the gas, during which the resistance is very high, to the ionized and subsequent arc condition where the electrical resistance is comparatively low and negative ineifect; characteristics which render the tube inherently unstable and exceedingly difiicult to effectively control.

In heretofore known systems and apparatuses of the class indicated cumbersome and expensive choke-coil and/or resistances are included in series with the various luminescent tubes in order to stabilize the operation of these tubes and to limit the flow of current during the conductive period of the tubes to desired safe values.

Another object of my invention is to limit and control the flow of current in the various gas filled tubes of a single luminescent system in a highly eificient and practical manner without sacrifice to the uniform brilliant operation of the tubes and the proportionate time duration of the luminescence thereof.

. tem or excited from separate electrical transforming apparatus connected with a single source of power. from a common source of high potential electrical energy there is a great tendency, due to the instability of tubes of the class indicated, for the tube of lowest starting potential or the tube of greatest conductivity when ionized, to become overloaded and to cause a non-uniform operation of the tubes taken as a group. All of these systerns and apparatuses are large and cumbersome requiring much expensive apparatus which is costly to maintain and operate and which is generally inefficient and unreliable.

Accordingly, one of the outstanding objects of my invention is to provide a system and apparatus of compact, inexpensive and practical construction for operating luminescent tubes or gaseous conduction devices of the class indicated in an economical and thoroughly reliable manner from readily available alternating current electrical .Illustratively, the tubes or devices 10, 11, and 12 are of approximately the same size and voltage rating while the devices 13 and 14 are of approx- Where a number of tubes are energized imately per cent increased size and voltage rating.

Each of the gaseous conduction devices (see Figure 2) is conveniently in the form of an elongated clear glass envelope 10a with metallic electrodes 10b and 10c mounted within the glall envelope and mechanically supported by sealed electrical terminals 10d and 10e respectively. A gas of such character and at such low pressure as to become luminescent upon proper electrical excitation, such as neon maintained at a reduced pressure, is enclosed within the glass envelope 10a.

As the column of gas within the envelope is excited by the application of a suitable electrical potential across the terminals of the tube, as described more fully hereinafter, the gas is ionized, and rendered conductive, and becomes luminescent giving forth, for neon, a red-orange glow. Where the proper potential is maintained across the terminals of the luminescent tube or gaseous conduction device, all as more particularly described below, the luminous glow of the gas is transmitted through the clear glass walls of the tube and gives a uniform and brilliant glow along the length of tube.

Referring now back to Figure l, the various luminescent tubes 10, 11, 12, 13 and 14 are preferably supplied with alternating current electrical energy from a readily available single phase source of electrical energy 15 illustratively 220 volts cycles, which is connected to the tubes by an electrical system and apparatus more fully described below. i

In accordance with the provisions of my invention electrical energy from source 15 is supplied the primary winding 16 of a single core transformer generally denoted at 17 by means of suitable conductors 18 and 19. A plurality of coil sections, preferably of an even number and of equal voltage and impedance ratings, illustratively four, 20, 2-1, 22 and 23 comprise the high voltage secondary winding of the transformer. Conveniently the primary winding 16 and the secondary winding 2021--22-23 are mounted on a single iron core diagrammatically indicated at 24.

The various secondary coil sections, 20, 21, 22 and 23 are preferably connected in series by means of conductors 25, 26 and 27 so that the electromotive forces induced in the several coil sections are additive.

In order that maximum secondary potential may be achieved with a minimum of expensive insulation, the amount and cost of which rapidly increases with the electrical potential for which the apparatus is to be insulated, the mid-point of the secondary winding is preferably grounded as at 28. While maximum electrical potential is established between conductors 29 and 30 connected respectively to coil sections 20 and 23 only one-half of this potential need be insulated against since but one-half of this maximum value exists between the high-potential conductor 29 and ground 28 and between conductor 30 and theground.

In addition to the economies in construction indicated above and a decreased danger to life and property because of the high electrical potentials employed, by grounding the seriallyconnected coil sections at a mid-point there is achieved a balanced transformer secondary system the advantages of which will appear more fully hereinafter.

The several gaseous conduction devices 10, 11 and 12 of equal ratings are supplied with highpotential electrical energy from combinations 01',

,for example, two of the four transformer secondary winding coil sections; the combination of coil sections connected to any one of the gaseous conduction devices is not repeated but each conduction device is supplied with electrical energy from a combination of series connected coil sections which is not duplicated in any of p the others.

For example, luminescent tube or gaseous conduction device 10 is supplied with high-potential electrical energy from the transformer secondary I winding coil sections and 21 which, as indicated above, are connected in series by a conductor 25, by way of the conductors 29 and 26. Likewise, tube 11 is supplied with high-potential electrical energy from coil sections 21 and 22,, which are connected in series by a conductor 26, by way of conductors and 27. And tube 12 is similarly supplied with energy from coil sections 22 and 23,

' serve a balanced condition in the secondary circuit of the transformer.

The, illustratively, two gaseous conduction devices-of increased rating 13 and 14 (about per 'cent greater resistance than tubes 10, 11 and 12) are so connected to the secondary winding of transformer 17 that a 50 per cent increased electrical potential is applied thereto all without disturbing the balance of the secondary circuit. Thus, referring to Figure 1, the tube 13 is supplied with high potential electrical energy from the secondary winding coil sections 20, 21 and 22 (serially connected, as indicated above, by conductors 25 and 26 respectively interconnecting sections 2021 and 2122) by way of conductors 29 and 27. Similarly, tube l4is connected to the serially connected " coil sections 21, 22 and 23 (interconnected by conductor 26 for sections 21-22 and conductor 27 for sections 22 23) by way of the conductors 25 and 30.

'In the operation-of my electrical luminescent sign system and apparatus, as high-potential electrical energy is supplied the various luminescent tubes, all as more particularly described above, these tubes become conductive, and hence luminescent, when the instantaneous values of the various applied potentials are sumcient to establish an ionized condition within the respective tubes. For a cycle supply of alternating current electrical energy the tubes are rendered alternatingly conductive and non-conductive, and consequently luminescent and non-luminescent, 120 times per 5 second (once for the positive half and once for the negative half of each cycle). Due to the persistence of vision the tubes appear to glow continuously.

As soon as the conductive condition is estab- J llshed'the resistances of the various tubes (initially very high) drop to low values which become efiectively negative. -In order to prevent the electric current in the various tubes or gaseous conduction devices from rising to excessive instantaneous values under these highly unstable conconduction devices decrease to values which, while Where capactive impedance elements are em- 'ployed in series with each of the several tubes the high inductance of the transformer secondary winding included in the complete energization circuit for any one tube is largely compensated for. The time required for the current to build p to a value sufilcient to cause a desired illumin tion of the tube is thus greatly reduced while the proportion of the time during which the tube is rendered conductive and a current of high density flows is brought to a maximum. This permits the tube to be luminescent a greater portion of each cycle of the impressed" potential, and the related flow of current, and thereby gives an increased brilliancy of operation.

Since each of the several gaseous conduction devices is supplied with high-potential electrical energy from diiferent portions of the transformer secondary winding a desired current density in each tube is independently achieved and a uniform brilliant operation of the various tubes is assured in spite of slight inequalities in tube construction and in the electrical characteristics thereof (starting potential, maintenance potential, initial un-ionized resistance, ionized resistance and the like). Thus highly efilcient operation of a luminescent sign system of the character indicated is achieved with a minimum of riods of these tubes, the current density of the tube or device 13, and hence the brilliancy of the luminescent glow emitted, may be effectively I limited by connecting the resistance element 36 in series with the high-potential circuit energizing the device.

Likewise, the difference in conductivity and luminosity of the other devices may be varied to achieve a uniform brilliancy of the entire luminous display.

LJU

As more particularly indicated above the high inductive resistance of the several individual luminescent tube circuits is largely compensated for by the condensersconnected in series with the respective tubes. In order to obtain maximum operating efliciency of my electrical system The use of the additional condensers 37, 38, 39.

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and 40 as indicated above compensates for the excess inductive reactance of the transformer secondarywinding coil sections and brings the power factor of the several parts of the secondary circuit to unity without, at the same time, undesirably affecting the balanced condition of the system and the current limiting function of the condensers connected directly in series with the several luminescent tubes.

My system and apparatus for operating a number of luminescent tubes in addition to assuring maximum uniform brilliant operation of the tubes permits a direct saving in cost of operation. The losses are minimized and the power required of .1 the source of supply energy is reduced to a minimum value for uniform brilliant operation of the luminescent display.

Thus it will be seen that there has been pro- ,vided in this invention a system and apparatus in understood that an uneven number of sections may be used where such a practice is found desirable, as where the secondary load circuit is unbalanced. Likewise, while single luminescent gaseous discharge devices or tubes are connected to various combinations of transformer secondary winding coil sections it will be understood that a plurality of series-connected luminescent tubes of reduced rating may replace one or more of the individual tubes as desired.

As many possible embodiments may be made of my invention and as many changes made in the embodiment hereinbefore set forth it will be understood that all matter described herein or shown in the accompanying drawing is to be interpreted as illustrative, and not in a limiting sense.

What is claimed is,

1. In 'a luminescent tube system having a plurality of luminescent tubes, in combination, a transformer having a secondary winding divided into a plurality of-series-connected coil sections arranged in equal numbers at opposite sides of a zero potential point of said winding, and a plurality of parallel tube circuits connected to the secondary winding of said transformer so that each of said circuits is connected to a particular grouping of the coil sections of said transformer secondary winding that is not duplicated in any of the companion tube circuits.

2. In a luminescent tube system having a plurality of luminescent tubes, in combination, a transformer having a secondary winding divided into a plurality of series-connected coil sections arranged in equal numbers at opposite sides of a grounded neutral point of said winding, and a plurality of parallel tube circuits connected to said winding so that each of said circuits is served by a particular grouping of the coil sections of said transformer secondary winding that is not duplicated in any of the companion tube circuits and so that the loads on opposite sides of the zero potential point of said secondary winding are substantially balanced.

3. In a system and apparatus of the character coil sections of said winding that is not duplicated in any of the companion circuits, whereby each of said circuits is operated at a voltage corresponding to thesum of the separate voltages of the coil sections included therein.

4. In a system and apparatus of the character described, in combination, a single phase single core transformer having a secondary winding divided into a plurality of coil sections, a plurality of devices having negative resistance characteristics, and a plurality of parallel circuits connected to said devices and to said secondary winding so that each of said devices is connected to a particular grouping of the coil sections of said secondary winding that is not duplicated in any of the companion circuits and is operated at a voltage corresponding to the sum of the separate voltages of the coil sections included therein, the connections between said secondary winding and said parallel circuits being such that the number of coil sections included in certain of said circuits differs from that included in the remaining circuits.

5. In an electrical tube system, in combination, a source of alternating current electrical energy, a transformer having a primary winding and a plurality of secondary winding sections, a plurality of gaseous conduction devices, means for connecting the primary winding of said transformer to said source, and means for connecting said gaseous conduction devices to non-repetitive combinations of the plurality of secondary winding sections of said transformer.

6. In an electrical luminescent tube system, in combination, a source of single phase alternating current electrical energy, a single phase transformer having a primary winding and a plurality of secondary winding coil sections, means connecting the primary winding of said transformer to said source, a plurality of luminescent tubes,

and means including impedance elements for connecting said tubes to non-repetitive combinations of the secondary winding coil sections of said transformer.

7. In an electrical tube system, in combination, a source of alternating current electrical energy, a transformer having a primary winding and an even number of secondary winding coil sections, means connecting the primary winding of said transformer to said source, a plurality of luminescent tubes, means connecting the secondary winding coil sections of said transformer in series forming a balanced secondary circuit groundedat mid-point, and means connecting said luminescent tubes to said last-mentioned means in non-repetitive combinations and maintaining the balance of said secondary circuit.

8. In an electrical tube system, in combination, a transformer having a primary winding and a secondary winding comprising a plurality of coil sections, a plurality of luminescent gaseous conduction devices, means connecting said gaseous conduction devices and said coil sections so that each of said devices is connected to a series connected combination of said coil sections that is not duplicated by the others of said devices, and capacitive means connected in parallel with the coil sections of said transformer secondary to said source, means including impedance elements for connecting said gaseous conduction.

devices to non-repetitive combinations .of the plurality of secondary winding sections of said transformer, and capacitive means connected in parallel with said secondary winding sections for improving the operation of said gaseous conduction devices.

CHARLES PHILIPPE BOUCHER.

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