US2015570A

US2015570A - Cathode ray photographic apparatus

Info

Publication number: US2015570A
Application number: US499297A
Authority: US
Inventors: Camil A Sabbah; Paul M Gray
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1930-11-19
Filing date: 1930-12-01
Publication date: 1935-09-24
Anticipated expiration: 1952-09-24
Also published as: GB392583A; GB383752A; FR726493A

Description

p 24, 1935- c. A. SABBAH ET AL 2,015,570

{CATHODE RAY PHOTOGRAPHIG APPARATUS Filed Dec. 1, 1930 Ihvehcors:

Cami! A. Sabbah,

Paul M. Greg,

by MW Their Att OT'TWGH.

Patented Sept. 24, 1935 UNITED STATES PATENT OFFICE CATHODE RAY PHOTOGRAPHIC APPARATUS Application December 1, 1930, Serial No. 499,297

5 Claims.

Our invention relates to apparatus for making a photographic record by the use of a cathode ray. Apparatus of this character heretofore constructed and not employing a Lenard window has necessitated the opening of the cathode ray tube in order to insert and remove the light sensitive member. The necessity of opening the tube each time that the light sensitive member is inserted and removed is objectionable since it means that the vacuum of the tube must be lost and reestablished each time that the tube is opened. It is the object of our invention to provide an improved cathode ray apparatus with which the light sensitive member may be exposed without requiring its being placed within the evacuated member.

Our invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is a view showing apparatus including a circuit diagram forming one embodiment of our invention; Fig. 2 is a fragmentary view drawn to a larger scale of a detail of the apparatus; and Fig. 3 is a crosssectional view thereof taken on the line 3-3 of Fig. 2.

The apparatus which we have chosen to illustrate is adapted to produce a photograph of a picture or view transmitted by radio. The transmitted impulses are received by the radio receiver l of any suitable construction-having the antenna 2 which picks up electrical impulses which vary in accordance with the shade of a successive elemental area of the picture being transmitted and which also picks up the synchronizing impulses by which the cathode ray of the receiver, to be described below, is caused to move in the proper manner.

The output circuit of the receiver l is applied to the input side of the electron discharge amplifier 3 whose output circuit includes the source of current shown as battery 4, the cathode 5 and the anode 6 of the cathode ray tube 1. Between the cathode and anode of the tube 1 is shown the perforated shield 8 which is electrically connected with the cathode 5 and through which the ray is projected. The end wall III of the tube, which it will be understood is vacuum tight, has the property of having higher conductivity transversely thereof than in other directions so that it provides numerous transverse paths of relatively high conductivity. Such a wall may be continuous in character and composed for example of graphite crystals extending transversely thereof.

In the drawing we have illustrated the wall as comprising a large number of transverse parallel conductors which are insulated from each other. A convenient method of constructing such a wall is to form a cable of fine insulated wire, for example lacquer insulated wire, binding the wires together by suitable means to form a solid mass and then cutting a thin transverse slice of the cable thus formed. In Figs. 2 and 3 we have illustrated a fragment of the wall Ill greatly magnilied showing the small transverse conductors ll separated by insulation l2. Arranged external to the tube and parallel with the end wall It is the auxiliary anode l3 shown as a fiat plate which connects with the anode 6 through a suitable source such as the battery l5 to raise its potential above that of anode 6 so as to produce in air a glow discharge from the particular conductor of wall Ill upon which the cathode ray impinges at any instant. Between the end wall Ill and the anode plate 13 is a narrow space which is adapted to receive the light sensitive photographic member I6, such for example as a photographic film upon which Lichtenberg figures are produced by the glow discharge which discharge may be invisible and ultra violet in character. This member l6 preferably lies close to or contiguous with the outer surface of the end wall l0.

While the nature of the discharge in the space occupied by the member I6 is not entirely under stood it is supposed that the electrons starting from the negative electrode, namely, the conductors ll of wall ill under the action of the electric field imparted to it by the cathode ray ionize the gaseous medium in that space. In sweeping over the various conductors of the end wall, the cathode ray acts like a commutator without weight. The positive ions produced fall back on the negative electrode and as they do so they recombine with electrons. The re-combination results in the emission of light quanta whose frequency is given by end wall III in the same manner in which the exploring ray is moved in the transmitter, we have shown the two pairs of electrostatic plates H, I. and II, 2| which are arranged at right angles to each other and between which the ray extends and is deflected in the well understood manner. Plates l1 and I! by a common lead and plates II and II by individual leads connect with the output circuit of the receiver I through the illter device 12. It will be understood that the synchronizing impulses being transmitted comprise two frequencies, one for convenience being termed the high frequency and the other the low frequency. Where it is desirable as in the present example to have the ray moved in spirals, the device 12 includes suitable means for splitting the high frequency wave or producing two components thereof which have phase differences of substantially 90. These two components are modulated in accordance with the low frequency wave. The apparatus for producing this result has not been illustrated in detail as it forms no part of our invention and is well known to those skilled in the art.

When a picture or view is being transmitted the picture impulses received by the radio receiver I after being amplifled by the amplifier 3 modulate the cathode ray emanating from the filament 5. The synchronizing impulses also transmitted are received by the receiver l and are flltered out by the device 22 whence they are conveyed to the pairs of plates l1, l8 and If, 20. As the modulated ray sweeps over the inner surface of the end wall ll of the tube the fllm I! although external to the tube is exposed in accordance with the intensity and the position of the ray, the fllm subsequently being developed in the usual and well known manner.

While we have illustrated our invention as arranged to receive pictures or impulses by radio it is not limited to such use but may be employed to record various electrical phenomena such for example as the wave form of alternating currents, surge discharges, etc., and where oscillographs heretofore have been employed.

What we claim as new and desire to secure by Letters Patent of the United States, is,-

l. Cathode ray photographic apparatus comprising a cathode ray tube having a cathode and a main anode and end wall comprising a plurality of separate insulated transverse paths of relatively high conductivity, said tube having means for laterally deflecting the cathode ray impinging on said end wall in accordance with a a received signal, and an external auxiliary anode separated therefrom by an open air space adapted to receive a light sensitive member.

2. Cathode ray photographic apparatus oomprising a cathode ray tube having a cathode and lo a main anode and having an end wall of insulation having a plurality of narrow transverse conducting paths and means for deflecting the cathode ray impinging on said wall, and an auxiliary anode external to the tube and spaced from said end wall, said space being open to the outside air and adapted to receive a light sensitive member.

3. Cathode ray photographic apparatus comprising a cathode ray tube having a cathode and a main anode and having an end wall including a plurality of small transverse insulated conductors embedded in insulating material, and means for deflecting the cathode ray across said end wall, and an auxiliary anode plate arranged beyond the end of the tube and separated therefrom by an open air space into which a photosensitive member may be readily inserted.

4. Cathode ray photographic apparatus comprising a cathode ray tube having a cathode and a main anode and having a flat end wall including a plurality of small transverse wires embedded in insulating material, and means for deflecting the cathode ray across said end wall, and an auxiliary anode comprising a flat plate arranged beyond the end of the tube and separated therefrom by an open air space adapted to receive a photosensitive member.

5. A cathode ray tube having a cathode and a main anode and having an end wall including a plurality of small transverse insulated conductors held by said end wall and means for deflecting the cathode ray across said end wall, and an auxiliary anode plate external to the tube and positioned opposite to and parallel with said end wall, an open air space being provided between the end wall and the auxiliary anode plate and arranged to receive a photosensitive member.

CAMIL A. SABBAH. PAUL M. GRAY.