US2347933A - Electronic view finder - Google Patents

Description

May 2 1944- R. L. CAMPBELL ELECTRONIC VIEW, FINDER' Filed Jan. 10. 1942' INVENTOR.

ATTORNEY Patented May 2, 1944 UNl'iED STATES PATENT GFFICE ELECTRONIC viEw mman Richard L. campbell, Maywood, N. .1.,assignor to Allen B. Du Mont Laboratories, Inc., Passaic. N. J.. a corporation ot Delaware application January 10,1942, serial No. 426,921

(ci. 17a- 6.8)

Claims.

This invention relates to a viewilnder that is particularly useful in connection with television cameras. By this invention a televisionvcamera man can monitor the scenes or objects which are being transmitted while panning and focusing the pick-up camera. The image which is observed in the view iinder is upright and can be made appreciably brighter than is possible with optical means. It can be used with diierent sorts of television cameras now known.

In carrying out this invention the view nder is I made up as a small monitoring unit in compact form that is adiustably mounted upon the camera itself in such a location that it can be conveniently adjusted and watched by the camera man as he operates the camera. Scanning and video signals are fed to the view iinder from the control unit that is provided for the camera itself so that the camera man has instantly the infomation that is being transmitted and can quickly make adjustments that may be needed for obtaining better results. The view inder circuits may be controlled in common vwith and simultaneously with the camera.

The invention may be understood from the description in connection with the accompanying drawing, in which:

Fig. 1 is a perspective view showing a camera and view finder mounted upon a tripod;

Fig. 2 is a block diagram illustrative of'A the invention; and v Fig. 3 is a diagram of electrical connections to the camera and view nder.

In the drawing, reference character i indicates a tripod with a universal joint 2 by means of which the camera 3 is mounted upon the tripod and can be turned to diierent positions by means of the handle The camera is provided with a lens that is focused by means of the handle 6 in the well known way.

The view finder 9 is connected to the camera 3 by a connection iii in such a manner that it is swung around with the camera as the camera is turned for panning the scenes, while at the same time the view nnder can be turned about this connection lil so as to be adjusted to diilerent v positions in a plane parallel to the sides of the camera 3. The controls for the view iinder may be mounted thereon. A light shield for the view finder is shown at l I.

A generator for synchronizing pulses is diagrammatically indicated at i9 in Fig. 2. Leads 20 and 2l for horizontal and vertical sweeps extend from generator i9 to the camera control unit 22, comprising camera. sweeps, view nder sweeps and main video amplifier. from which the lead 23 extends to carry the output picture signals.

A lead 24 applies the video signal from the video amplifier to the supply unit 25 for the view finder 9, and power is also supplied to this view finder supply-unit 25 by means of the lead 26 which may lead, for example, from a source of volt alternating current. A power and video signal cable 2l leads from the unit 25 to the view nder 9.

A cable 30 for carrying the camera sweep signals, the camera video signal, the view nder sweeps and other control wires is connected between the unit 22 and the camera 3. Lead 32 applies the horizontal and vertical sweeps to the view nder 9 to which the lpower and the video signal are applied by the cable 21. Sweep voltages are thus'fed from the camera control unit 22 through the camera cable 30 and lead 32 to the view finder 9. When an iconoscope camera is used, keystoning, and the use of circuits operating magnetically militate against using the camera sweep for the 'View iinder; thereforev the sweep circuits for the view ilnder 9 are brought directly from the cable 30 as indicated by the dotted line. The isolating stages for the view finder are ener- ,gizedfrom the sweep input circuits 20, 2l of the camera control unit 22, which are fed from the synchronizing generator i9. This is not necessary with an orthicon camera since there is then no keystoning, so that the view finder sweeps can be connected to the camera sweep lines.

The connections for the view finder are shown in more detail in Fig. 3. The horizontal sweep signal from lead 32 (Fig. 2) is applied to the output stage 42, from which it is applied by leads 38 to the horizontal deection plates 39 of the cathode-ray tube 40 that is located in the view finder 9 (Fig. 1). A lve inch intensifier type cathode-ray tube has been found to be very suitable as a view finder. Thevertical sweep circuit signal, also from lead 32 (Fig. 2), is applied to the output stage 43 (Fig. 3), from which it is applied by leads '44 to the vertical deflection plates 45. The video signal from the camera 3 (Fig. 2) is applied to the video amplier 46 (Fig. 3) and thence by lead 4l to the control grid 48 of the tube 40 oi' the view finder 9. The other elements of the gun structure of the tube 40 with their control circuits are of the well known sort and are shown somewhat diagrammatically in Fig. 3 without detailed description thereof. The resistor network 49 isindicated for applying Way.

'I'hls invention has been found to be practical in actual use. due, among other things. to the facts: that an intensifier type of cathode-ray tube 40 is used so that suillcient brightness can be made to appear upon the screen, thus cnabllng one to use the view iinder 8 where there is very strong light such as direct strong sunlight or high intensity studio lighting; electrostatically controlled deflection is used so that straight am plifiers can be used for applying the sweep to the cathode-ray tube in the view nder; vertical and with its attendant weight does not have to be carried by the camera; and the controls for the video, for the sweeps, and for the cathode-ray tube are mounted on the view finder so that they are in convenient reach of the camera man. 'I'he video signal for the view finder 9 is obtained from an output amplifier in the camera control and is fed over a coaxial cable to the view finder supply unit 25 where it can be ampliiled and from which it is fed to the view nder which has an amplifier 4B for driving the cathode-ray tube 40 in the view nder.

What is claimed is:

1. A television pick-up camera, a view finder adjustably mounted on said c amera, a control said camera to said view finder, a lead from said control unit to said view ilnder supply unit and a lead from said view finder supply unit to said view ilnder.

2. A television pick-up camera, a view finder mounted on said camera, a control unit for said camera, means comprising leads for feeding scanning and video signals from said control unit to said view finder, a supply unit for said vicw finder, and leads connecting said supply unit to said view nder and said control unit.

3. A television pick-up camera, a view finder mounted on said camera, a control unit for said camera, sweep circuit connections from said control unit to said v.2.w linder, and means comprising a lead from a power supply unit and a lead from said control' unit to said supply unit and a lead from said supply unit to said view nder, to supply power and video signals to said view finder independently of said sweep circuit connections.

4. A television pick-up camera, a view iinfier mounted on said camera, a control unit for said camera, a view finder supply unit, and means for feeding scanning and video signals from said control unit to said view iinder, said last named means comprising a lead from said camera to said view finder, a lead from said control unit to said view iinder supply uni*u and a lead from said view ilnder supply unit to said view finder,

"said view finder being provided with an intensifier .for increasing the brightness of the picture on the screen thereof.

5. A television pick-up camera, a view iinder mounted on said camera, a control unit for said camera, means for feeding scanning and video signals from said control unit. to said view finder, leads connecting said supply unit to said view finder and said control unit and a power supply for said view nder independent of said camera.

RICHARD L. CAMPBELL.`

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