US2052133A - Television apparatus - Google Patents

Description

Aug, 25, 1936. L. DE' FOREST TELEVISION APPARATUS Original Filed April 24, 1931 2 Sheets-Sheet 1 a a Z,

amen/00 A566 defireai:

Aug. 25, 1936. 1.. DE FOREST 2,052,133

TELEVISION APPARATUS Original Filed April 24, 1931 2 Sheets-Sheet 2 lee defia (1, 35; I

Patented Aug. 25, 1936 TELEVISION: APPARATUS Lee de Forest, Hollywood," Calif., assignor to American Television Laboratories, Inc., a corporation of Delaware Original application April 24; 1931, Serial No.

5, apparatus for receiving, and. reproducing tele- Fig. 5.upon ascanning disk;

vised pictures and images. Fig. 7 is an enlarged sectional view showing It is well known to those familiar with the the details in the construction of a preferred art.that images can be converted into electrical form. of individual Kerr celladapted for use. in impulse modulations which may be transmitted connection with this invention;

by. radio or by wire andreceived at distantpoints, Fig. 8 is a, sectional. view which may be con- 10 where, through the medium. of so-called' televisidered as having been taken in a plane represion receiving. apparatus they can be converted sented bythe line 8-8 in Fig. 7. into images corresponding to the transmitted As. pointed out above, the method involved in images. The reproduction of the images at the the. present inventionis one in which the image receiving, station is generally accomplished by is produced directly by means of an apertured 15 means of a pulsating neon light associated with scanning disk of the usual type, which is pro a scanning disk, and since the quantity of such vided with novel means adapting the same to use light available. is verysmall, the reproducedimwith a constant light source of high intensity. age is dim. and isincapable of satisfactory mag- The apparatus. employed, as illustrated in the 20, nification. It, therefore, becomes a primary obdrawings, consists in a general'way of a light ject of this invention to produce an apparatus of source. anda. scanning, disk of the conventional the class described whereby the televised'image Nipkow type which are associated wth means may be reproduced with light. of suflicient infor modulating or valvinga bright beam or area of tensity to permit its: magnification. light by m'eansof a succession of rapidly moving as, Pursuant to the attainment ofthis object the light valves which are preferably arranged in present invention contemplates the use of a. novel spiral. relation upon the scanning disk. type of-scanning disk which may be used with a In Fig. '1 the rectangle A' represents a small source of'lightof high intensity and is provided, intensely brightly illuminated, area on the back with light valves adapted to be controlled by side of a scanning disk I H! which is made of nonimpulsestfroma television receiverfor governconducting material. The light thrown on A 30; ing the quantity of light passing from the source comes preferably from an intense source of'light throughthe successive aperture of the. scanning shown in Fig. 2 as an arc IH behind which is a disk. Through the medium of this. apparatus I reflector H2 and in front of which is a condense I am able to reproduce thetelevised image with a ing.- lens ll3. This source of. light and lens are much'brighter light which may be magnified. so. so arranged'as to throw on a Nicol prism H4 a as to produce a sharp image of much. greater beam of light, which is limited to the desired proportions than has heretoforebeen possible. square area by means of an opaque frame H5.

The construction of a preferredembodiment A succession of apertures lllil preferably round. of my invention, together with other objects at in form,is arranged in-the usual spiral form pierc- 40-tending its production, will be best understood ing the non-conducting scanning disk III], as 40 from the following descriptionof the accompanyclearly shown; in. Fig. 1. Behind each aperture ing drawings which are chosen for illustrative is.p1aced.a-smallKerr cell I H in such a manner purposes onlyand in whichthatthe portion of the light of the brightly il- 1- is. an elevational view showing animluminatedareaAwhich passesthrough a given provedtype of scanning disk contemplated by aperture H6 must also pass through the indivdual 5 thisinvention; p Kerr. celllocated directly in frontof said aper- Fig. 21 is an end elevation illustrating the manture. nerof-utilizing the scanning disk shown in Fig. 1; One armature of each Kerr cell is connected Fig. 3 is an elevational View similar to Fig. 2, by means of the suitable conductor M9 to a corshowing a modified form ofscanning disk; responding segment I20. of a commutator Hi 50, Fig.4 isan elevational viewillustrating a modiwhich is arranged around a shaft I22 which carfiedform' of Kerr-cell construction which may be ries the disk. Theseveral commutator segments employedin the-device contemplated by this inare so dimensioned. and spacedand, a brush I23 vention; is so placed that only the active armature of the Fig; 5, is a. sectional view which may be con- Kerr cell which is at that moment traversingthe 55,

532,454,, now Patent No. 2,026,872 dated January 7, 1936. Divided-and this application September S, 1931, Serial No. 561,512

10 Claims.

sideredgashaving been. taken in a plane represented by the line .5-5 in Fig. 4

Fig 6 isa sectional view illustrating the manner. of mounting the cellconstruction shown in illuminated area A is connected in the electric circuit. The other armature of each of the Kerr cells is connected to a common conductor I24. This common or bus conductor is connected through a conductor I24 to the metal shaft I22 which carries the scanning disk I I0. The brush I23 and shaft I22 are connected through conductors I25 and I26 to the output terminals of the secondary I21 of a transformer I28. Inserted in series in this secondary circuit are high voltage polarizing batteries I29, the purpose of which is to impress across the armature of Whichever Kerr cell happens to be in circuit a constant high voltage polarizing potential. The output of a television receiver amplifier (not shown) is led to the terminals of the primary I30 of the transformer I28. By the above described arrangement, which is the usual circuit arrangement for modulating or valving light transmitted through a Kerr cell by means of received alternating current energy, as employed in talking picture recording and in certain previously known television receiving systems, I am able to modulate, or

valve, the light which is passing through a given 25 aperture on the scanning disk, because as is well known, the action of the Kerr cell is to elliptically polarize the beam of light, which, from practical considerations, is the equivalent of rotating through a greater or less angle the plane of polarization of a polarized light beam passed therethrough.

As shown in Fig. 2, I provide in front of the scanning disk and directly opposite the polarizing Nicol prism II4, the analyzing prism I I4a whose axis is turned through 90 relative to the angle of the first. In front of this second prism at a suitable distance I place a projecting lens I 3I by means of which the small image which passes through the prism I Mat is enlarged and thrown upon a screen I32, so that the enlarged image is seen, preferably by reversed projection, by the eye of the observer at I33.

The arrangement I have just described possesses many advantages over the heretofore used devices for television projecting wherein a single Kerr cell is employed to valve the concentrated light from a powerful arc lamp, and said valved light beam thereafter being distributed over the screen by means of a scanning disk containing lenses arranged in spiraled relationship. For example, by my method only a small portion of the light passes through any one Kerr cell, by virtue of which the cell is not subjected to damaging heat. Moreover, the cells are kept in very rapid motion and thereby very effectively air-cooled. Furthermore, the Nicol prisms are not subjected to the intense heat of a point of concentrated arc beam, as is the case where a single Kerr cell and small Nicol prisms are employed.

Fig. 2 shows the synchronized motor I driving by means of the speed-multiplying gears I36I3'I the shaft carrying the scanning disk III] and commutator I2I. The shaft and circuit are shown grounded at E, (Fig. 5).

I38 shows the 3 leads to the conventional three phase motor I35. I have shown no detailed means for synchronizing the scanning disk at the receiver with that at the distant transmitting station, inasmuch as I synchronize my receiver by any one of the well known and effecive synchronizing systems, and as this forms no part of my present invention it is unnecessary to go into detail regarding same at this time.

Fig. 3 shows a somewhat improved method of using the Kerr cell and commutator, whereby troubles of contact commutation between a fixed brush and rapidly moving commutator segments are avoided. In the arrangement shown in this figure the individual Kerr cells III are arranged in spiral relationship as before, with the one armature of each connected to the common bus bar I24 which is connected, preferably by means of four conductors I40, 90 degrees apart, to the shaft I22 of the. scanning disk IIO, thence through the conductor to one terminal of the polarizing battery I29 and preferably grounded. The other terminal of this polarizing battery is led through the secondary I2I of the transformer I28, as described in connection with this same circuit as shown in Fig. l and thence through the conductor I25 to the insulated plate I4I.

Around the circular periphery of the scanning disk I I0 is arranged a series of conducting plates I42 of considerable area. The outer surfaces of these plates are turned to conform with the curvature of the scanning disk, and fixed plate I4I, similarly curved, is so arranged as to come in very close proximity to, but not quite in contact with the sectors I42. Each sector I42 is then connected by means of a wire I43 to the insulated armature of its appropriate Kerr cell, (I I1) as is clearly shown in Fig. 3. Inasmuch as the capacity of the condenser formed between fixed plate MI and any individual moving armature plate I42 on the periphery of the scanning disk is thus made large compared with the capacity of any individual Kerr cell the electrical action across the Kerr cell which is thus put into circuit is essentially the same as that shown in Fig. 1. If desired, a stopping, or safety condenser C can be inserted in the circuit of Fig. 1, as well as in that of Fig. 3, and otherwise the operation of the arrangement shown in Fig. 3 is identically the same as that above described in connection with Fig. 1.

As a further modification of this arrangement of a multiplicity of Kerr cells in spiral formation upon a scanning disk, I have shown in Fig. 4 a single glass tube I50 arranged in the proper spiral form and carrying on its inner shorter face a common conductor, or armature, I5I Opposite this conductor and at an appropriate distance therefrom, and suitably spaced relative to each other, are a series of small armatures I52, a lead from each of which is brought out through the wall of the glass tube and led to its corresponding large-area plates I4I. These plates are arranged as shown in Fig. 3 about the circular periphery of the scanning disk.

The common conductor I5I may be in the form of a metallic conductor deposited on the inside of the spiral formed glass tube, or may be located on the outside thereof, leaving only one set of armatures of the Kerr cell inside the glass tube. This glass tube is preferably not circular in cross section, but is flattened as shown in Fig. 5, which figure shows clearly the common armature I5I, in this case located outside of the glass tube on its bottom surface, and an individual short armature of the Kerr cell I52 10- cated inside of the glass tube with its lead I53 brought out through the flattened wall of the tube, sealed therethrough, and carried on to the conducting plate I42. The fixed condenser armature plate I4I is also shown in close proximity to the moving plate I42 and connected to the conductor I 25a. I

Inasmuch as the action of the Kerr cell to equivalently rotate the plane of polarization of the light beam is more effective thebloser together are the two armatures, or electrodes, of the Kerr cell, I prefer to locate the individual armature of :said' cell close to-th'e flattened bottom of the glass tube; '1' prefer to leave a gap of say ten one-thousandths of an inch between the armature I52 and the bottom wall of the tube, or between the two metal armatures of the Kerr cell in case both armatures are placed within the glass vessel. The most suitable metal for such Kerr cells armatures I have found to be gold, or some other suitable metal gold-plated. I prefer to use as my light rotating liquid in the Kerr cell a solution of nitro-benzol.

Fig. 6 shows how the spiral formed glass vessel containing the multiplicity of Kerr cells is attached to one face of the insulating scanning disk. The glass tube is supported on the metal bracket I60 which is fastened by suitable means to one side of the scanning disk lllla. This figure shows a small aperture IBI drilled through the face of the scanning disk whereby a small beam of light is permitted to pass through the Kerr cell after having traversed the polarizing Nicol prism 2 I4. Having traversed the space between the armatures of the Kerr cell and having its plane of polarization more or less rotated by such passage the beam of light is shown thence passing through the analyzing Nicol prism 2l4a.

In Fig. 7, I have shown one form of small individual Kerr cell consisting of an elongated glass capsule I65 containing two metal armatures l l1a-l lBa, suitably separated, each with its lead brought out through an opposite end of the capsule, as shown by H9 and l24a. Reference numeral I66 indicates the extension of the glass envelope, whereby the Kerr cell is filled with nitro-benzol solution and then sealed off. These individual Kerr cells are then mounted in proper relationship around the scanning disk and the armature is connected respectively to the common conductor and to the individual commutator leads as described in connection with Fig. 1 or Fi 3.

Fig. 8 shows a sectional view of one of these individual Kerr cells taken at right angles to the view shown in Fig. 7. It is here seen that the passage of the beam of light, indicated by arrow B, is through the small diameter of the glass envelope, and between the two armature plates of the cell. I so place these individual Kerr cells that the prolongation I66 is pointed towards the center of the scanning disk so that when the disk is in rapid rotation centrifugal force causes the fluid to completely fill the space between and surrounding the two armatures of the cell, leaving the air bubble (which is usually present after sealing off the glass capsule) in'the prolongation of the capsule.

Many other modifications and changes in details will occur to those skilled in the art without 1. For use in a television receiver: a scanning disk provided with a multiplicity of apertures; a Kerr cell at each of said apertures; means for rotatlrigsaid iscanning "disk; and. means for electrl callychargingthe successive Kerr cells from'a. television receiver during. the rotation. of said disk. I

2. use atelevision receiver: a scanning diskpi ovid'ed with a;rnu-l'tiplicity of apertures; a Kerr cell at each of said apertures; a commutator on -sajid s'canning disk; means for connecting one armature of each Kerr cell to one segment of said commutator; a common conductor on said scanning disk; means for connecting the other armature of each Kerr cell to said common conductor; and means for connecting the common conductor and the successive segments of said commutator to the output of a television receiver.

3. For use in a television receiver: a scanning disk provided with a multiplicity of apertures; a Kerr cell at each of said apertures; a series of commutator segments on the periphery of said disk; means connecting one armature of each Kerr cell to one of said commutator segments; a common conductor on said disk; means for connecting the other armature of each Kerr cell to said common conductor; and means for connecting the successive commutator segments and the said common conductor to the output of a television receiver.

4. For use in a television receiver: a scanning device embodying; a scanning disk provided with a multiplicity of apertures arranged in a spiral path; a transparent tube containing a polarizing fluid mounted on said disk opposite the apertures therein; means for rotating said scanning disk; means for projecting a beam of polarized light toward said disk and over an area traversed by said apertures; a plurality of armatures on opposite sides of said tube adjacent said apertures; means for connecting said armatures with the output of a television receiver during the movement of said aperture through the illuminated area; and an analyzing prism for passing the light coming from said apertures.

5. For use in a television receiver: a scanning device embodying; a scanning disk provided with a multiplicity of apertures arranged in a spiral path; a Kerr cell mounted on said disk at each aperture; means for rotating said scanning disk; means for illuminating an area of said disk traversed by said apertures with a beam of polarized light; means for energizing each Kerr cell during its movement through the illuminated area from a television receiver; and an analyzing prism for passing the light coming from the successive Kerr cells.

6. For use in a television receiver: a scanning disk provided with a. multiplicity of spirally arranged apertures; means for rotating said disk; a spiral tube filled with polarizing fluid mounted on said disk opposite said apertures; armatures on opposite sides of said tube adjacent said apertures; and-means for connecting said armatures with the output of a television receiver during the movement of said apertures through a predetermined area.

7. In combination a rotatable scanning member provided with a plurality of scanning apertures, a Kerr cell for each aperture, a commutator, means connecting one armature of each Kerr cell to a corresponding segment of said commutator, a common conductor, means connecting the other armature of each Kerr cell to said common conductor, and means connecting the currentconductor and the segments of said commutator successively to the output of a television receiver.

8. In combination a rotatable perforated scanner having a plurality of scanning apertures and a plurality of sets of Kerr cell electrodes carried by said member, there being one 5 set of electrodes adjacent each of said apertures, and a polarizing medium between each set of electrodes.

9. The combination according to claim 8, in

which all the said sets of electrodes are mounted within a single enclosing envelope.

10. The combination according to claim 8, in which the said sets of electrodes are mounted within a common spiral enclosing envelope containing a solution of nitro-benzol.

LEE DE FOREST.

Images