US2153140A - Oscillograph - Google Patents

Description

Aprifi 4, 1939. w, DiEHL ET AL 2,153,149

05 C ILLOGRAPH Filed Dec. 28, 1934 INVENTOR.

as W. F. DIEHL .SCHRADER ATTORNEY.

Patented Apr. 4, 1939 OSCILLOGRAPH William F. Diehl, Haddonfleld, and Harold J. Schrader, Haddon Heights, N. 3., asaignors to Radio Corporation of America, a corporation oi Delaware Application December 28, 1934, Serial No. 759,498

4 Claims.

The present invention relates to oscilloe'raphs, and particularly to oscillographs oi the cathode ray type wherein a cathode ray tube produces on the end-wall thereof an electro-optical pattern which represents any transient phenomenon applied to the control system of the tube.

It is an object of the present invention to provide a cathode ray oscillograph apparatus which will have combined with it in a single unit, all necessary amplifiers, timing axis oscillators, and all necessary controls.

Further objects of the invention are those providing a cathode ray osclllograph apparatus which is extremely compact, which is portable, and in which the operation may be so controlled that the entire operation can be had from impressed alternating currents, and also providing as a part of the complete apparatus all necessary rec'tifiers and filter devices.

Still other objects of the invention are to provide a cathode ray oscillograph which may be controlled and synchronized from an external source, or which may be controlled and synchronized internally by the frequency of the energy supply source, or which may be controlled and synchronized by the signals applied for controlling the deflection of the developed cathode ray beam along one axis of the oscillograph.

Still other objects and advantages will become apparent and at once suggest themselves to those skilled in the art by reading the following specification in connection with the accompanying drawing, of which the single figure thereof shows schematically a cathode ray oscillograph constructed in accordance with the present invention. i

Referring now to the drawing:

The cathode ray tube l upon the fluorescent viewing screen 3, of which it is desired to observe a transient or re-occurrent phenomenon, is provided with the usual sets of beam deflecting electrodes 5, 5 and 7, l. These deflecting electrodes are arranged to produce fields at right angles to each other so that the cathode ray beam, conventionally represented 9, passing through the tube between the electron-emitting source, conven his application Serial No. 489,957. With the electrostatic beam deflecting system shown in the accompanying drawing, although it is to be understood that electro-magnetic deflecting means, or a combination of electro-magnetic and electro-static deflecting systems may be substituted, signals which it is desired to observe are applied to the deflecting electrodes 5, 5-from a suitable source, not shown, connected to the input terminals l9, l9. These signals are then distributed by way of a switching arrangement 2! so as to be supplied to the control electrode of a vacuum tube amplifier 23 by way of a capacity element 25 and a suitable variable potentiometer 21. The amplified signals appearing in the output circuit of the tube 23 are then directed back through the lower contact arm of the switch member 2| (as shown) so as to be fed through the capacity coupling condenser 29 to one of the deflecting electrodes 5. By varying the point at which contact is made with the resistor of the potentiometer 21, the signal strength supplied to the control electrode of the tube 23 may be varied, and thus the voltage applied to the deflecting electrode 5 may be varied. This then will control the sensitivity of the instrument and the gain control, and at the same time vary the amplitude of the image signals appearing upon the screen 3 'in accordance with the applied voltage. In the event that amplification of the signals supplied to the terminals l9, i9 is not desired, the switch member 2i may be moved to the lower contact members, in which event the amplifier 23 is disconnected from the deflecting electrodes 5, 5, and these signals then are applied directly to the deflecting elements by way of the capacity 29.

In order to control the rate at which the transient applied to the vertical system of deflecting electrodes 5, 5, traverses the screen 3 in a direction from right to left, or vice versa, there is provided a means for connecting a source of horizontal controlling signals to terminal members 3i, 3i which are then fed by way ofthe switch member 33 when the contact arms thereof rest upon the terminal points 34, 34 to the amplifying tube 35, as was above explained in connection with the vertical beam deflecting signals. These signals are applied to the control or input electrode of the tube 35 by way of the condenser Bi and the potentiometer 39 to which connection is made to the grid electrode of tube 35 at the point 41 in order to control the amplification factor of the tube. The signals supplied to the terminals 3|, 3! thus are amplified in the tube 35, and with the switch arms making contact with the terminal points 34, 34 after amplification are passed through the capacity coupling 43 to the horizontal deflecting electrodes 1, 1 so as to cause the beam within the tube to move in a horizontal plane in accordance with the voltage existing between the two deflecting elements 1, 1.

With the switch arm 33 moved down so as to rest upon the contact members 44, 44, the signals applied to the terminal points 3|, 3| are then fed directly through the lower arm of the switch through the condenser coupling 43 to the deflecting electrode system 1, 1 without amplification so that in this event the horizontal controlling signals control the deflecting of the cathode ray beam 9 in a horizontal plane without either internal control or without amplification after their receipt at the terminal or points 3|, 3|. In the event that it is desired to provide an oscillator for controlling the timing axis, that is, the sweep path in a horizontal direction, an oscillator tube 45, which is preferably a tube of the gas discharge type, provided with a controlling electrode, is arranged within the system. Connected with the output circuit of the tube 45, there are pro vided a number of condenser elements 46, 41, 48 and 49 which are adapted to be charged from a source of voltage, to be later described, through resistor elements 50, 5| and 52. In order to connect individual condenser elements 46-49 with the oscillator tube 45, a switching arrangement comprising a pair of switches 53, 54 is provided so that in accordance with whichever condenser 46-49 is connected to the plate or output electrode of the tube 45 by way of the switch will determine the rate at which the tube 45 breaks down to discharge the particular condenser, these condensers being connected with the tube output circuit by way of the switch 53.

In order that the period of charge may be controlled, and thus provide an oscillating system which will develop a saw-tooth wave of the desired characteristic, the periodicity of charge and discharge must be variable over an extremely wide range of frequencies, and in accordance with the present arrangement this variation in frequency may be assumed to be between 20 and 15,000 cycles, although it is to be understood that this variation is merely illustrated by way of example and not in any limiting sense. Therefore, the switch arms 53, 54 are inter-connected so that as the switch arm 53 is moved so as to connect any individual condensers 46-49 with the output circuit of the tube 45, a corresponding change in position of the switch element 54 occurs, and, therefore, different combinations of resistance and capacity connected in the output circuit of tube 45 are possible, and the frequency at which the tube breaks down to discharge the condenser may be varied.

In accordance with this invention, an oscillator tube of the type which has become known in the art as the RCA-885 is preferable although. of course, other types of tubes having somewhat similar characteristics may readily be substituted. In order to control still further the rate at which the condensers 46-49 discharge through the tube 45 so that the operation is not dependent upon the tube break down voltage exclusively, and in order that there may bean interlocking feature between the frequency of alternating current supplied as the power source for the system, or between the impressed transients upon the terminals l9, l9, or between some special external synchronizing signal source, there is connected with the input circuit of the tube 45 by way of a transformer 51 some appropriate controlling signal.

which is applied to the grid or control electrode of this tube so as to trigger it at the desired rate. As the invention has been illustrated, these signals are applied by way of a switching arrangement 59 consisting of three separate or simultaneously acting switch arms 60, 6| and 62. Each of the switch arms 60, 6| and 62 is adapted to contacted by the switch arms, serve to control or trigger the tube 45 in accordance with some independent external synchronizing signal which may be applied to the terminal points 13. This signal may then be in the form of an impulse signal rising sharply to a maximum value, and then immediately dropping off to a minimum value so that the grid or control electrode of the tube 45 is supplied with a voltage which will immediately make the tube highly conductive, or where desired the external synchronizing signal may be of any other suitable wave formation and shape such as the usual nonsymmetrical sawtooth wave formation, or a symmetrical sawtooth wave formation, or for that matter any other desired wave formation.

As the invention has been illustrated, with the switch arms 6| and 62 upon the upper contacts 64, 65, and 66 of the switching arrangement, the tube 45 is operating under the control of the output from the amplifier tube 23 and, therefore, is in accordance with the transients supplied to the terminals l9, l9. So arranged, a portion of the output of the tube 23 is directed through the circuit including the resistance element 15, the impedance element 11, and the conductor 19 so as to be applied to the terminal point 64. Thus these signals control the voltage on the grid of the tube 45, and thus serve as a means for definitely determining the time at which any of the condenser elements 46-49 which happen to be associated with the output circuit of the tube 45 are discharged by way'of the tube.

In order to supply operating voltages for the entire system, the usual power supply line is connected to the terminal points 8|, 8|, and through transformer 83 these signals are then supplied to a full wave rectifying device 85 which may, where desired, be a type of tube known in the art as the RCA-80, and the output from this tube after being smoothed by way of an appropriate filter chain 86 comprisinginductance and capacity elements, appears across the voltage divider generally designated 81. Between the end terminals of this voltage divider 81, suitable operating voltages for various tubes of the system may be obtained. In order to supply heating current for the various heater elements of the tubes 45 a separate secondary winding 89 is provided on the transformer. An additional secondary winding 9| provides heating current for the tubes 23 and 35, and still a-third winding 93 provides heating current for the cathode ray tube In order to supply operating voltages for the cathode ray tube a separate rectifying tube 95 has been disclosed, and incombination with this tube there has been arranged a smoothing condenser 91, and the operating voltages are obtained across potentiometer or voltage divider conventionally designated as 99.

If now it is desired to control the operation of the oscillator tube 45 in accordance with the frequency of the energy applied to the terminal points iii, the switch arms 50, SI and- 62 are moved to the central contact points 61, 68, and 69 so that a portion of the same current that is supplied for heating the heater element of the tube 45 is applied by way of conductors I and NH, and thus the tube 45 is controlled at the frequency of the energy supplied to the power supply unit in order that the synchronisation may be produced internally,otherwise the operation of the tube 45 is similar to that already explained when it is operating under control of the signals applied to the terminal points l9, l9.

If now it is desired, however, to control the operation of the tube 45 from a separate external signal, serving for synchronization, the switch arms G0, 6! and62 are moved to the lowermost contact points 70, H and I2 so that whatever signals appear across the terminal points 13 will be applied to control the operation of the tube 45. It now having been explained that the tube 45 may be triggered so as to control the discharge of any of the capacity elements 46-49 which happen to be connected with its output circuit by signals represented either by the transient to be observed by an external signal or by the power supply, it can be seen that with the oscillator tube 45 connected by way of the conductor I03 and the resistance [04 to theuppermost contact point of the switch element 33, a signal will be supplied through the condenser 31 andthe potentiometer 39 so as to control-the operation of the tube 35, and thus the tube 35 can operate under the control of the signal supplied to the terminal points 3|, or under the control of the oscillator tube 45 depending upon whether the switch arms 33 be placed upon the center contacts 34 or upon the uppermost contacts 155, and consequently the voltages applied to the deflecting electrodes 1, I of the tube I may be controlled accordingly.

As was hereinabove suggested, the voltage divider 81 which comprises separate resistance sections I06, I01, I I18 and IDS is arranged to supply all D. C. tube voltages for the tube 45, and the two tubes 23 and 35 as is obvious from the connections shown to the various terminal points on these separate resistance sections and as is well understood in the art. The separate rectifier tube 95, together with the voltage divider generally designated as 99, is arranged to supply all D. C. operating voltages for the cathode ray tube l as is immediately obvious due to the connections between the various electrode elements of the tube I and the various points on the voltage divider.

For example, the conductor I09 between the grid or control electrode l3 of the tube I and the point on the section III! of the voltage divider 99 will serve to control the bias on the control grid l3 so as to control the brilliance of the resulting light spot on the screen 3 of the tube. Similarly, the conductor HI serves to control the voltage on the first anode electrode of the tube when appropriately adjusted with respect to the resistance section I I2 of the voltage divider. The potentiometers [l3 and H4 respectively, connected at the lowermost end of the voltage divider 99 when suitably adjusted serve to apply to the deflecting electrode system 5, 5 and I, I respectively, biasing voltages so as to make it possible to center the spot produced by the oathode ray beam 9 upon the screen 3, and also which make it possible to frame the image resulting.

It is to be understood in connection with the foregoing explanation that all of the various switch arm members are preferably provided with controlling elements, as are all adjustable re-' sistors, capacities, potentiometers, and the like which are adapted to protrude beyond the front panel of the cabinet in which the oscillograph is to be mounted so that the control may be accomplished with ease. The cathode ray tube i when positioned within the cabinet is so arranged that the screen 3 is preferably viewable from 'the same side of the cabinet as is used to support the controlling means for the various switches, resistors, potentiometers, capacities, and the like so that suitable adjustment may be made to the beam with a minimum amount of difliculty.

While the invention has been suggested and described in one of its preferred forms, it is to be understood that the foregoing explanation and description is merely intended to be illustrative, and therefore it is to be understood that any and all modifications may be made therein which fall fairly within the spirit and scope of this disclosure as disclosed by the hereinafter claims wherein is claimed and desired to be secured by Letters Patent the following:

1. In oscillograph apparatus, a cathode ray tube having means therein to produce an electron beam and associated means for controlling the path of the produced beam and means to control the operation of the tube comprising an oscillation generator for controlling the path of the beam in one plane, means to control the beam motion in a transverse plane under the influence of signals received from an external source, power supply means to supply operating voltages for said tube and selective means to control the oscillation generator bysignals received from an external source, or signals received from an external synchronizing signal source or from the power supply means.

2. In oscillograph apparatus, a cathode ray tube having means provided for developing an electron beam to cause fluorescent effects upon the viewing wall thereof and an associate beam deflecting electrode system for controlling the traversal path of the fluorescent viewing wall of the tube by the beam, means for controlling the beam deflection in one plane in accordance with a transient effect to be observed, an oscillation generator for developing saw-tooth wave formation electrical energy having a control circuit, a power supply system energized from an appropriate source of alternating current energy for supplying operating voltages to the tube, and selective means for controlling the electron beam path in a direction transverse to the direction of control produced by the transient to be observed under the individual control of the transient signal to be observed or the power supply or an external synchronizing signal, said selective controlling means comprising switching apparatus for connecting one of the aforesaid signals to the control circuit of the oscillator.

3. In oscillograph apparatus, a cathode ray tube having means therein to produce an electron beam and an associated electron beam deflecting system for causing the ray to traverse the tube fluorescent screen according to pre-established patterns of traversal, a power supply system for supplying energy to said tube, said power supply system comprising a source of alternating current, a rectifler and. a voltage divider, means for connecting the beam deflecting system with the voltage divider so as to position the electron beam within the tube to a desired point on the fluorescent screen in the absence of controlling voltages applied to the beam deflecting system, an oscillation generator for controlling the motion of the cathode ray beam within the tube in one pre-established plane, means associated with the oscillation generator for varying between pre-established limits the normal oscillation frequency of the oscillator system, and switching means for selecting between said oscillator and external signalling impulses for controlling the beam motion in the same plane as the oscillation generator, for said beam deflection, a second source of electrical en erg'y for controlling the beam deflection in a second direction transverse to said-flrst-named controlled direction to produce a wave trace of a phenomena to be observed and switching means for controlling the frequency of the said oscillator from the said eflect to be observed, or an external synchronizing signal or the power supply voltage.

4. The system claimed in the preceding claim comprising in addition an amplifying system connected with both the source of signals to be observed and with the signals to control the beam motion in the plane transverse to the control produced by the said signals to be observed and switching means for'interchangeably controlling the beam motion from said supplied signals with.

and without amplification.

- WILLIAM F. DIEHL.

HAROLD'J. SCmADER.

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