US2047175A - Electric lamp for producing modulated lights - Google Patents

Description

.July 14, 1936- H. BRASELTON;

ELECTRIC LAMP FOR PRODUCING MODULATED LIGHTS Filed Aug. 25, 1932 3 Sheets-Sheet 1 INVEN' I'OR y 1935- c H. BRASELTON 2,047,175

ELECTRIC LAMP FOR PRODUCING MODULATED LIGHTS July 14,1936 c. H. BRAsEL oN ELECTRIC LAMP FOR PRODUCING MODULATEDLIGHTS Filed Aug. 25, 1932 3 Sheets-Sheet 3 Patented July 14, 1936 UNITED STATES PATENT OFFICE ELECTRIC LAMP FOR PRODUCING MODULATED LIGHTS Chester H. Braselton, New York, N. Y., assignor to Sirian Lamp Company, Newark, N. J., a corporation of Delaware Application August 25, 1932, Serial No.-630,378 3 Claims. (Cl. 116-122) This invention relates to electric lighting devices of the type which produces a modulated light for use especially in devices necessitatin very rapid changesof intensity such as television receiving apparatuses.

One of the objects of the invention is to provide a modulated light in which the energy source for supplying the illumination is independent of the incoming wave signal.

Another object of the invention is to provide a modulating electric light in which a gaseous Several embodiments of the invention have been illustrated in the accompanying drawings in which:

Figure 1 is a sectional side elevational view of one form of lamp embodying the invention; Fig. 2 is a front elevational view of the elements of Fig. 1;

Fig. 3 is a sectional plan view of the elements connecting the cathode of the structure of Fig. 1;

Fig. 5 is a sectional side elevational view of the elements of another embodiment of the invention;

Fig. 6 is a front elevational view of the elements of Fig. 5;

Fig. 7 is a sectional rear elevational view of still another modification of the invention;

Fig. 8 is a. sectional side elevational view of the elements of Fig. 7;

Fig. 8a is a detail view in perspective of a slight modification of the control electrode of Fig. 8; l

Fig. 9 is a planview of the structure shown in Figs. 7 and 8;

Fig. 10 is a sectional side elevational view of still another embodiment of the invention;

Fig. 11 is a front elevational view of the elements of Fig. 10;

Fig. 12 is a sectional plan view of the construction of Fig. 10 taken on the line l2-l2 of that figure:

Fig. 13 is a perspective view of one of the shields shown in Figs. 10 and 11; and- Fig. 14 is'a plan'view of the elements of Figs. 10 and 11.

Referring now more specifically to the drawings the invention is shown in Fig. l as comprising a bulb ill of transparent material such as glass, quartz, or the like with a press ll formed integral with the bottom of the bulb and extending upwardly inside thereof in the usual .manner of forming electric lamps. The press II,

however, is preferably provided with a circular enlargement I2 adjacent the center thereof 15 the top of which is flush with the top of the press ii and the purpose of which will be evident as the description proceeds.

A tubular cathode I 3 formed of nickel or other suitable material and coated on its surface with electron emitting material It is mounted vertically adjacent the center of the bulb upon an insulating member l5 which has a hole It extending through it with a shoulder l1 toreceive the'lower end of the cathode. The electron emitting material l4 may be any of the well known materials used for that purpose such as the oxides of the alkaline earth group of metals.

ormixtures of such oxides held together with a suitable binder. The member I5 is preferably provided with a depending peripheral flange [8 which may rest upon the press H and if desired a suitable rim I 9 may be provided on the press I I at the central portion to secure the insulating member i 5 in position on the top of the press and prevent horizontal displacement thereof. member l5 may be made of any suitable insulating material such as quartz vitreous insulators, or the like, and preferably one which is opaque so as to prevent any light rays from passing through it.

A housing formed of similar material in the shape of ahollow cylinder having a diameter slightly larger than the insulating member I5 is placed thereover to rest upon the top of the press H. The housing 20 may be held in position upon the press i I by means of a pair of semi-circular clamps 2| which surround the housing at' the bottom thereof, resting upon a shoulder 22 provided for that purpose in the housing, and are welded to two short support rods 23 which are The upper end of the tubular cathode. This housing holds the cathode securely down upon the insulating member i3 and the insulating member l3 down upon the press II.

A pair of short connecting rods 21 may be mounted in the press I l at the center thereof being short enough to terminate under the insulating member l3 and to these rods I weld or otherwise secure the ends of a hairpin filament 23 which extends up through the inside of the cathode, the loop end terminating in a cavity 33 provided for that purpose in the upper wall 23- of the housing 23. The filament 23 may be coated with a suitable insulating material so as to prevent short circuiting between the adjacent legs of the filament and between the filament and cathode.

' Electrical connection may be made to the cathode l3 by means of a band 30 of metal which may be welded around the lower end thereof with its ends bent out radially from the cathode. and these ends may be welded to a rod 3| which is sealed in the center 'of the press i I between the connectors 31 and which may be bent outwardly and upwardly to reach the band 30, passing through a suitable groove 32 provided in the insulating member l3 as shown in Fig. 4.

A control electrode 33 which may be formed of a spiral coil of wire, as shown in Figs. 1 and 2, or which may be formed of wire mesh or merely a flat metal plate, as desired, is provided with a hole or open space 33 and may be positioned ad- Jacent the housing being mounted on a support rod 33 which is also sealed in the press II. The housing 23 adjacent the control electrode 33 is provided with a hole 33 which may have any configuration depending on the configuration of the light desired, the hole 33 being preferably somewhat smaller than the opening 33.

On the outside of the control electrode 33 I provide a plate 31 which may be formed of nickel if desired although highly refractory metals such as tungsten and molybdenum may be used. The plate 3! acts as the anode for the device and is provided with a hole 33 in the center thereof which is preferably larger in diameter than the opening 33 in the grid 33 as the illumination in the opening 33 in the housing 20 is to be observed through the hole 33 in the anode. The anode may be supported upon a support rod 33 also sealed in the press II. In order to make the electrical connections to the device a pair of wires 33 may be connected to the filament connectors 21, while a wire 3| may be connected to the cathode connector 3i. Similarly a wire 32 may be connected to the control electrode support rod 33 and a wire 33 may be connected to the anode support rod 39.

With the elements thus assembled the bulb may be connected in the usual manner to a vacuum pump and an oven placed over it to raise the temperature of the bulb and associated parts while the pump is exhausting the air and other gases which may be present. During this time the filament is energized by passing a current through it so as to raise its temperature and heat up the associated parts, and as much of the occluded gases and vapors are removed from the elements of the device as possible. when all of the gases have been removed a small amount of ionizable gas suchas neon may be admitted at a pressure preferably under mm. of mercury. Other gases may be used such as argon, helium, krypton, and zenon, or mixtures of such gases, the monatomic gases being preferred. Also metal vapors, such as the vapors of mercury, caesium, and rubidium may be added to increase the conductivity of the gas and for color effects. The lamp may then be sealed off and is ready for use.

When the lamp as described is completed it may be connected in a circuit as indicated in Fig. 1. Thus the two filament leads 3! may be connected to the secondary 33 of a transformer 33, the primary 33 of which is connected to the source of alternating current supply. The wire 32 connected to the control electrode may be connected to the input circuit 31 which carries the incoming signal, the other side of the input circuit being connected through the biasing battery 33 to the cathode connecting wire 3|. A B battery 33 or other source of plate potential may have its negative side also connected to the cathode lead wire 3| while the positive side may be connected to the wire 33 which forms the anode connector 20 there is a difference in potential between the 25 anode and the cathode, electrons will move from the cathode to the anode but inasmuch as the housing 23 surrounds the cathode and shields it from the anode at all points, except at the opening 33 in the wall thereof, all of the electron stream will tend to pass through this opening in order to reach the anode. Inasmuch as the lamp is filled with an ionizable gas the gas is ionized by this electron stream and the result is an intense illumination appearing in the hole 36 as the ionic discharge passes through it to reach the plate. Similarly to the action of a vacuum amplifying tube the negative charge on the control electrode will tend to repel the discharge and cause it to return to the cathode, while a positive charge on the control electrode will speed the discharge on its way toward the anode,

- and thus variations of the potential of the control electrode caused by the incoming signal will vary the density of the discharge. Inasmuch as there is a hole 38 in the anode an observer can stand in front of the anode and look through it and through the opening 33 in the control electrode at the hole 36 which, as has been said above, will appear intensely bright as long as the control electrode is positively charged or at zero potential, and the illumination will fade out as the control electrode builds up on the negative side. 'i

Such a lamp is especially desirable for use in television reproducing apparatus where a spot of modulated light is caused to move across the field of vision in any one of a number of different ways which are now the subject of considerable research and experimentation.

For use with certain types of television devices it may be desirable to have an elongated opening for the area of intense illumination and if so the construction of Figs. 5 and 6 may be used. Here the filament, cathode, and cathode supporting parts are identical with those already shown and described with the exception of the housing which has in its front an elongated slot 3| instead of the hole as shown in the housing 23. 7 The control electrode 32 is similar to the control electrode shown in Fig. 1 but has an opening 33 corresponding in shape tothe opening il in the housing 33. In like manner the anode 53 com prises a plate with an elongated slot 33 therein so that the slot Si in the housing 58 may be seen through it.

In assembling the construction of Figs. 1 to 4 inclusive the filament is first welded to the support rod 21 and then the member I! is placed over the filament. The cathode is placed over the filament and the cathode band 38 welded to its support rod 3| The housing 20 is then placed over the cathode and over the member l5 and the housing clamps 2| are welded to the support rods 23 to hold the whole unit in position. The control electrode and anode may then be mounted in position as indicated. The construction shown in Figs, 5 and 6 may be assembled in the same manner.

In Figs. 7, 8 and 9 I have shown another embodiment of the invention in which the insulating refractory housings 28 and 58 of Figs. land 5 are eliminated and the control electrode itself becomes the housing for preventing the discharge between the cathode and anode except through a predetermined opening. This device is shown mounted in a bulb 58 having a press 51 somewhat similar to the press ll of the preceding figures and having a similar circular extension 58 at the center thereof whose top is flush with the top of the press i I.

A heating filament 59 may be supported on a pair of support rods 50 which are sealed in the press 51 at about the center thereof and this heater may be surrounded by a cylindrical cathode Gi similar to the cathode I 3 of the preceding figures and coated with electron emitting material in a similar manner. the cathode 6| may be provided with a securing band 62 of metal which may be welded to a support rod 63 also sealed in the press 51 adjacent the filament supports 88. A sleeve 64 of insulatlng material having a diameter large enough to surround the cathode support rod G3 as well as the filament supports 60 is provided resting upon the surface of the enlarged portion 58 of the press 51. A disc 65 also made of insulating material may be placed on top of the sleeve 54, a suitable hole 68 being provided in the center thereof to receive the cathode while a flange 61 may also be provided in the outer periphery to fit over the upper edge of the sleeve 64.

I provide a control electrode 68 preferably of a refractory metal such as tungsten or molybdenum in a tubular form to surround the cathode. Thus a pair of plates 69 may be pressed to form a semi-cylindrical portion with a flange 10 at each side thereof. The two plates are placed together with the concave sides adjacent flanges 10 may be welded. This holds the disc 65 and the sleeve 64 securely in place upon the top of the press. The upper end of the control electrode 68 is closed by means of an insulating disc 14 which fits down inside of the electrode 68 and is provided with a recess 15 to receive the top of the cathode, thus spacing the cathode at the top from the control element. The disc 14 is held in place by suitable lugs 11 which may The lower end of be formed on the upper edge of the control element 88 and which are then bent over on top of the disc ll as shown.

The control element 88 may have a small hole 18 in the side thereof and an anode 19 may be placed directly in front of this hole and supported upon a pair of support rods 88 which may be sealed in the press 51 at each side of the sleeve 84. The anode is provided with a hole 8i which is larger in diameter than the hole 18 in the control element so that the intense light passing through this hole will be evidenced as viewed through the hole in the anode.

In assembling the device just described the filament is first welded to the support rods 60 and the cathode is then slipped over the filament and welded to the support rod 63. Then the sleeve 04 is placed over the cathode and filament upon the top of the press and also the disc 65 is placed over the cathode to rest on top of the sleeve, and the control element 68 is slipped down over the cathode, the support rods I2 passing through the grooves II provided for that purpose in the flanges 18. The control element is then welded in'place by welding the flanges 10 to the support rods I2. This holds the insulating sleeve and insulating disc in position and the insulating disc 14 is then positioned on top of the cathode inside of the control element 88 and the flanges 'II bent over, which holds it in position and spaces the cathode from the control element.

The device just described works similarly to the devices of Figs. 1 to 6 inclusive. As the con trol element itself is also the shield it will prevent any discharge from passing to the anode except through the opening in the side thereof and hence the intense illumination will appear at this opening.

In some instances it may be desired to protect the edges of the opening 18 in the control electrode against the intense heat produced by the discharge passing therethrough. In Fig. 8a a construction to accomplish this purpose is shown in which the hole 18a in the control electrode is made somewhat larger with a slot 18b at one side thereof. A bushing 19a of some highly refractory non-metallic material may be inserted in the hole 18a, a suitable lug 19b being provided on the outer end of the bushing to hold it in place when the bushing is rotated in the hole. The hole through the bushing should have the same diameter as the hole 18 in the control electrode described above but as the bushing can stand a higher temperature than the metal of the electrode there is less danger of the edges of the opening melting or otherwise being destroyed by the heat or discharge.

If it is desired to have an elongated slot for the opening the construction shown in Figs. 9 to 14 may be employed. Here the press, cathode, and filament construction are the same and the sleeve 64 is employed to surround the filament and cathode support posts as in the construction just described. The control electrode 82, however, is formed of two plates which are bent in a semi-cylindrical form but which are provided with a flange 83 at one side only so that the edges of the semi-cylindrical plates where there is no flange form the opening 85 through which the light and discharge pass. The control element is supported upon one support rod 86 only, which is positioned at the extreme end of the press 81 opposite the anode end and to which the flanges 83 are welded similarly to the manner described in connection with Fig. 7. However, the

insulating disc 88 at the bottom is provided in addition to the hole 88 for the cathode with a suitable groove 88 in which the bottom of the control element may fit. A radial groove II in 5 the side of the member 88, (see Fig. 13), communicating with the groove 88 permits the flanges 88 to extend outwardly toward the support rod 88. The disc may also have a depending flange 82 for fitting over the sleeve 84. This construc- 10 tion holds the two sides of the control element firmly and prevents warping due-to variations of heat and cold so that the slot 88 through which the discharge passes will not open or close.

The top of the control element is held in a 16 similar way by a disc 83 which'is provided with the grooves 80 and 8|, shown in the disc 88, and a recess 84 in the center to receive the upper end of the cathode. The disc 83 is also provided with a plurality of notches 88 into which lugs 81 20 attached to the control element may pass and be bent over the top of the disc thereby holding the disc securely to the control element and spacing the cathode therefrom at the top.

The anode may comprise a plate 98 mounted 25 upon a support rod 88 which is sealed in the press 81 opposite to the support rod 86. The plate 88 may be provided with an elongated slot I which is slightly larger than the slot 85 in the control element.

30 If desired the opening through the control electrode may be provided with refractory edges to prevent destruction by the intense heat similarly to the construction described in connection with Fig. 8a.

35 The elements of this device are assembled similarly to that shown in Figs. 7, 8, and 9 and no description of the assembly thereof is believed to be necessary.

It will be seen from the above that I have pro- 40 vided a lamp the lighting energy of which is obtained from a source entirely independent of the incoming modulation signal and that the light produced by the lamp will be varied in accordance with a very minute voltage modulation which is 45 impressed upon a suitable control electrode. This is a great advantage over lighting devices where the energy for producing the light is derived from the modulating light signal inasmuch as in the present invention the intensity of the light 50 may be enormously increased over any of these prior art devices. It is also. possible to eliminate the necessity of a powerful incoming modulated signal as the control element of my device will respond to very minute changes in incoming volt- 55 age and hence it is not necessary to amplify an incoming signal as for instance a television signal to any great extent thereby producing a more true reproduction of the signal as it eliminates 'the inherent distortion usually accompanying large amplification.

In the several embodiments of the invention I have shown one form of the anode as comprising a plate of metal but it will be understood that any metallic electrode may be used to act as an 65 anode such as a single wire, for instance, which is positioned in front of the openingthrough which the discharge passes. It is desirable, however, to

make the anode large enough so that it will not overheat inasmuch as the temperature thereof is raised considerably by bombardment and a small wire, for instance, may become white hot when subject to the discharge. In like manner the control electrode of Figs. 1 to 6 inclusive may be made of wire mesh if desired or formed of a plate, the important requirements being that the control electrode be near the opening through which the discharge passes and large enough to aifect the potential of the region immediately adiacent to such opening. When the filament has been shown as connected to the secondary of a transformer and perhaps preferably adapted to operate on a low voltage it will be evident that it may be designed to operate on any desired voltage as high as 110 or higher.

While the invention has been shown and described particularly in connection with a lamp used for television reproduction it is to be understood that the invention is not limited to television use but may be employed wherever it is desired to modulate a source of light as for sound-on-fllm recording or any type of signal work.

Many modifications of the invention may be resorted to without departing from the spirit thereof and I do not, therefore, desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I desire to claim and secure by Letters Patent is:

1. In a device of the class described an envelope,

a press within said envelope, a cathode moimted on said press, means to heat said cathode, an anode spaced from said cathode, a control electrode positioned between said anode and cathode, and a shield between said cathode and anode, and oathode and control electrode, and having a small opening in the vicinity of said control electrode.

2. In a device of the class described an envelope, a press within said envelope, a cathode mounted on said press, means to independently heat said cathode, a shield completely surrounding said cathode only, said shield having a small opening in the side thereof, an anode positioned in front of said opening, a control electrode positioned between said anode and cathode, and an ionizable gas within said envelope. 5o

3. In a device of the class described an envelope,

a press within said envelope, a cathode mounted upon said press, independent means to heat said cathode, a shield completely surrounding said cathode, said shield having a small aperture in one side thereof, an anode positioned directly in front of said aperture, said anode having an opening therein slightly larger than the aperture in said shield and in alignment therewith, and an electrostatic control electrode positioned between said anode and cathode, and between said anode and shield, and removed slightly from the com-- mon axis of the opening in said anode and the aperture in said shield, and an ionizable gas with- 55 in said envelope.

CHESTER H. BRABEL'IUN.

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