US1695924A - Television apparatus - Google Patents

Description

Dec. 18, 1928. i l `1,695,924`

" S. M. KNTNER' TELEVISION APPARATUS Filed oct. 15,1926 2 sheets-sheer v1 INVENTOR` WITNESSES;

ATTORNEY Patented Dec. 18, 1928.

UNITED STATES PArlsrrr OFFICE.

SAMUEL M. KINTNER, 0F PITTSBURGH, PENNSYLVANIA, ASBIGNOB TO'WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA.

' TELEvIsIoN APPARATUS.'

Application lred October 15, 1926. Serial No. 141,728.

This invention relates to devices used in the transmission of pictures. Such devices ordinarily include a scanning apparatus at the sending station' and a device at the receiving station for reproducing the picture. My invention is applicable to both the scanning device and to the picture-reproducing device.

It has heretofore been proposed to provide, in such devices, a rotating .disc havin@ acircular or a spiral row of lenses. As tle disc must be rotated at high speed, large centrifugal stresses are thereby introduced. To provide sufficient strength to lsustain such stresses is particularly diiiicult in a structure partly of glass and partlyof metal. The lenses, because they differ greatly in density from the disc itself, increase this diiculty by causing highly localized inertia forces.

Itis an object of my. invention to provide adisc for use in devices of the classes indicated which shall avoid the-difliculties encountered when lenses are mounted in the moving disc.

It is a further object of my invention to provide a disc andal focusing device integral therewith. Y

It is a further object of my invention to so add the focusing devices to the disc'as to produce a substantially homogeneous structure. e

It is a further object of rmy invention to avoid causing any change of a mechanical character in the rotating body by the provision of the focusin devices. n

It is a further o ject of this inventlon to form focusingdevices of the material of they revolving disc itself.

. It is a further object of my invention to i provide a rotating disc which may be driven at high speed without danger of breakage.

Itis a further object of my invention to reduce the number of lenses required in a scanning or picture-reproducing device.

It is a further object of my invention .to

provide a focusing device which shall notv introduce any substantial mechanical alteration of the disc itself, whereby the .disc shall have a substantially uniform density.

It is a further object of my invention to provide a plurality of concave reflecting lsurfaces in a disc, at a minimum expense.

Other objects of my invention will be apparent from the following description and the accompanying drawings, in whichz Fig. 1 is `a view, partly diagrammatic and partly in section, showing my invention applied to on-e form of scanning device;

Fig. 2 is a similar view showing my invention applied to another form of scanning device;

Fig. 3 yis a similar view showing the application of the invention to a picture reproducingdevice; and

Fig. 4 is a front elevation of the rotating part of the mechanism shown in the other figures.

In Fig. 1, the lens 1 is a diagrammatic representation of any optical system intended to produce an image of the object 2. The image is reflected by means of a concave mirror 3, -which is one of a series of mirrors, best illus- 'trated in Fig. 4.

As shown in Fig. 4, the mirrors are formed adjacent to the circumference of the disc 5, the center ofwhich is in the axis of the shaft 6. In certain forms of device,`th'e concave mirrors may be formed in a spiral instead of adjacent to a circumference. The hub 8, keyed to the shaft 6, carries both the disc 5l and the first member 9 of a train of reducing gears 9, 11, 12 and 13, by means of whichthe refracting device 14 is driven at a slower speed than the disc 5.

. The refracting device is of glass and includes an annular portion 15 having a prismatic cross section. The angle of the prism varies progressively from point to point along the circumference of the annulus. LAs a consequence of this variation, the glass tapers outwardly in one portion vof the annulus.

'lliv This outward taper diminishes progressively At this point, there is an abrupt change in theshape of the prism. At all other points throughout the annulus, the change 1n the shape lis gradual. The abrupt change is. shown at 16 in Fig. 4.

A photo-electric cell 21, suitably positioned with respect to the parts just described, constitutes a usual part of many picture-transferring systems. The amplifier 22 and the leads extending therefrom are intended to represent any system by Vwhich the changes ing-device 14, with its prismatic portion 15 described in connection with Fig. 1. The

disc 5 in Fig. 3 is'similar in construction to the' disc 5 in` Fig. 1.

The apparatus shown in Fig. 2 differs from that shown in Fig.,1`b y the omission of the lens 1. The concave mirror 31 corresponds to the concave mirror 3, but, because of the absence of any optical system corresponding to the lens 1, this mirror will, in general, have a longer radius of curvature. The other portions of Fig. 2 are like the corresponding portions of Fig. 1 and need not be separately described. Fig. 2 is presented to show how, by proper choice of the curvature of the concave mirrors, the mirrors, by themselves, may be made to perform the function of the optical system represented by the lens 1. Obviously, by choosing an intermediate radius of curvature for the mirrors, an optical system of less magnification than ,that represented in Fig. 1 may be employed.

In the operation of the device, light which comes from the object 2 is caused to produce an image at the `point 32in Fig. 1 by means of the optical system 1.1 The light from this image, or from the object itself, if the system shown in Fig.v 2 be used, is reflected by the concave mirror toward the refracting device 14. It is refracted by this device to an extent and in a sense which depends upon the angle of the prismatic section of the annulus.

The light, as it emerges from the refracting device, falls upon the photo-electric cell 21. Preferably, this cell is provided with a small light opening so that only a small portion, practically a point, of the object 2 or of the image 32, is correlated with the opening of the photo-electric cell at-any one time. The

' illumination of the cell and, consequently,

the modulation of the transmitted energy is thus made to correspond to the brightness of any one point of the object 2 at any one time.

As the "disc 5 revolves, the motion of the mirror 3 at right angles to the plane of the section in Fig. 1 causes the point in the object 2 corresponding-to the opening of the photo-'electric cell to trace a line at right angles to the plane of said section. `As vthe mirror 3 passes beyond the position in which it is inoperative relation to the object 2 and the photo-electric cell 21, and the next mirror of the set represented in Fig.' 4 comes into said vof said line to the other. The passage of successive mirrors through the operative position is thus accompanied by the tracing of lines inwone direction in the scene, and the position'of the mirror at' any one instant is thus correlated to one coordinate o f the point in the object or scene corresponding to the opening of the photo-electric cell.

- Therotation ofthe disc 5 is accompanied l by a rotation of the refracting device 14. The position of the image 33 in front of the photoelectric cell is shifted in the plane ofthe section in Fig. 1 by theaction of the refracting device. This is indicated on the drawing by showing two positions of the image 33. The one shown in solid lines corresponds to a portion of theannulus 15 tapering outward;

the one-in dotted lines'corresponds to the por-- tion of the annulus at which thetwo faces are parallel.

The shift is progressive, the image 33 being moved farther and farther in one'direction asthe angle of the rism changes gradually and being shifted a ruptly in the other direction when the shoulder 16 in the refracting device passes the operative position.v For clearness,lthe window in the photoelectric cell is shown at a little distance from the plane of the image 33. Preferably, the window is in the planeV of the image. The

whole image 33 does not illuminate the photo-electric cell. Onnly that portion 'of the image which is immediately in front of the opening inthe housing ofthe photo-electric cell controlls the illumination of the cell.

The point in the object 2, correspondingto the opening in the photo-electric cell, varies, therefore, with the position of the refracting device 14, and this variation is at right angles to the variation caused by the rotation of the disc 5. The position ofthe refracting device 14 is, therefore, correlated to a second` co;-

ordinate of the point in the scene or object 2- The two positions, therefore, that of the disc 5 and that ofthe refracting device 14, liX the two coordinates of the point in the .scene which is to control the modulation of the -transmitted ener i The transmitte energy controls the brightness of the source of light in the projector 23 at the receiving-station. This control is effected by'any meanslmown to the art; The

system used to transmit the modulated energy and to control the brightness of the projector in correspondence to the modulation does not form anypart of my invention and, for this reason, is not described.

The lightfrom the' projector 23 is refra'cted by the moving prism 25 and falls upon the mirror 3 in a direction fixed by the position of the refr-acting device 24. The mirror 3 re fleets this light to the screen 35. The position of the point at which the reflected light impinges upon the screen 85 is dependent, therefore, upon the position of the rofl-acting device 2st. It is also dependent upon the position-of the mirror 3 which changes with the rotation of the disc 5. l

he co-ordinates of the point on the screen illuminated by the projector' 23 are fixed, therefore, by the positions of the refracting device 24 and the disc 5. The illuminated point traces a line at right angles to the plane of the section (Fig. 3) for each passage of a mir-ror 3 throughthe operative position. These lines progress as the refractor 24.- rotates, and the direction of said progression is parallel to said plane. The lines move .abruptly to their original positions when the shoulder 16 in the prismatic portion of the refracting device passes the operative position.

In the manufacture of the disc 5, the depressions which are to be the concave mirrors may be produced either by stamping, as illustrated in the drawing, or by grinding or by any other convenient method. The curvature of these mirrors is greatly exaggerated in the drawing for the purpose o f clearly showing them. Actually, the stamping or grinding changes the shape of the disc so slightly that it produces no sensible weakening of the disc. n

After the depressions have beenformed, they are given approximately their final shape by a grinding operation and are rendered opy tically correct. The stamping or preliminary grinding andthe finer grinding and the figuring may all be performed with automatic machinery, with'the result that the disc 5, with its series of mirrors, may be produced inexpensively.

Preferably, the mirrors are spherical 1nir rors but other forms of reflectors may bel used. The concave surface only of the disc 5 need be of good reflecting character. The remainder of the disc preferably will have as small a reflecting power as can conveniently be obtained. For example, the di sc may be made of stainless steel or plated with chromium and4 all of 1t except the mirrors covered with a non-` reflecting substance, such as platinum-black, or the disc may be made of dull metal and the mirrors alone plated with a reflecting metal.

As the disc 5 is rotated at high. speed, severe centr1fugal strams are caused, but, because the concave mirrors introduce substantiallv no weakening of the disc, the dise may such stresses.

vio`usly, a very much greater ratio may be used, if desired. Y

This invention has the advantage over a disc carrying a plurality of lenses, which has 4been used heretofore, that the cost of the spherical mirrors is much less than the cost of the lenses. My invention has the further advantage that a disc having spherical mirrors may be rotated at a much higher speed without breakage than is possible if lenses are employed, and also 4the advantage that the spherical mirrors will canse very much less unbalancing of the disc than would be caused by lenses, and, consequently, vibration of the rotating parts, with consequent blurring of the picture, will be diminished.

It has the further advantage that the disc and focusing devices constitute one integral body. ,u l

Although I have illustrated and described specifically only a few modifications of mv invention, many other changes will be apparent to those skilled in the art and I do not intend to include any limitations except such as are indicated in the claims or are required by the prior art.

I claim as my invention:

l. In a translating device for picture transference, a rotatable member of approximately disc form and a series of reflecting devices disposed in rotative sequence on said rotatable member, each of said reflecting devices having its reflecting surface a surface of revolution, whereby each reflecting device is capable of producing a point focus.

2. In a translating device for picture transference, a disc, means for rotating said disc about its axis, a plurality of reflective-focusing devices disposed in rotative sequence on one face of said disc, each of said reflecting devices having its reflecting surface a surface of revolution, whereby each reflecting device is capable of producing a point focus and an optical system including each of said reflective devices in turn, whereby the position of 'said included reflective device relative to the non-rotating parts of said optical system may be made to correspond to one coordinate of the points in thepicture.

3. In a translating device for picture transference, a disc, means for rotating said disc about its axis, a plurality of reflective focus` ing devices arranged in circumferential sequence on one face of said disc and an optical system including each of said refletcive de- .vices in turn, whereby the position of said included reflective device relative to the nonrotating parts of said optical system may be made to correspond to one coordinate of the points in the' picture, said optical system also including a moving element, the position of which may be made to correspond to the other coordinate of said points.

4. In a translating device for picture transference, a rotatable member and a plurality each of said focusing devices having its re-' fleeting surface a .surface of revolution,

' whereby each focusing device is capable of producing av point focus land said member having substantially the same mechanical strength in a radial direction at the positions of said focusing devices as at other postiions.

5. vIn a translating device for picture transference, va disc of sheet material, concave mirrors constituting depressions in the surface of said disc and means for rotating the disc about an axis eccentric to each of said mirrors.

6. In atranslating device for picture transference, a disc of sheet material, concave portions constituting depressions in the surface of said disc, means for rotating the disc about an axis eccentric to each of said portions, and a reflective surface material on the concave portions.

' 7 In a translating device for picture transference, a disc of sheet material, concave portions constituting depressions in the surface of said disc,1ne'ans for rotating the discabout an axis eccentric to each of said portions, and a plating of highly reflective metalon the concave portions.

8. In a translating'device for picture transference, a disc ofsheet material, concave por tions constituting depressions' in the surface of said disc and means for-rotating the disc about an'axis eccentric to'each of saidportions, the surface of said concave portions being finished with optical accuracy to constitute them focusing devices.

9. In a translating device for picture transference, a disc of sheet material, a plurality of concave reflecting portions constituting depressions in the surface of said disc, means for rotating the disc about an axis eccentric to each of said portions.

In testimony whereof, I have hereunto subscribed my name this 12th day of October, 1926.

SAMUEL M. KINTNER.

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