US2402168A - Method and means for generating multiline sweep patterns - Google Patents

Description

H. LIFSCHUTZ Filed March 21, 1942' FIRST WA E FOURTH WA VE THIRD WA VE TIME L/M/ TE R CIRCUIT SAW- 7007/! GENERA 7' 0R SAW- TOOTH GENERATOR SECOND WA vs IRST WA VE TIME llll 1 June 18, 1946.

l/VPU? 5 n A H m a u H D FROM m m m m a Patented June 18, 1946 UNITED STATES PATENT ore-ice METHOD AND MEANS FOR GENERATING MULTILINE SWEEP PATTERNS Harold Lifschutz, Washington, D. 0., now by judicial change of name Harold Lyons Application March 21, 1942, SerialNo. 435,723

(Cl. 315-2d) (Granted under the act of March a, 1883, as amended April 30, 1928; 370 0. G. 157) 11 Claims.

number of sweep lines desired. The sweep lines produced in the foregoing manner will not be horizontal with respect to the vertical deflection plates of the oscillograph, and when pulses are applied to the vertical deflection plates in synchronlsm with the sweep, the pulse indications on the lines of the sweep pattern are not at right angles thereto.

Sweep circuits are provided in the prior art for generating horizontal multi-line sweep patterns in which pulse indications are produced at right angles to the sweep lines. In these systems, saw tooth wave forms are applied to the horizontal deflection plates of an oscillograph, while a, complex wave form is simultaneously applied to the vertical deflection plates in phase with the voltage applied to the horizontal plates. The complex wave form provides application of constant voltage to the vertical deflection plates during the time that each saw-tooth wave form applied to the horizontal plates propagates from a minimum to a maximum value, or during the period of each wave when the sweep lines of the pattern are generated. Such a wave form is so characterized that the values, or the amplitudes of the constant voltage portions of the wave. progressively decrease upon application of each cycle of saw-tooth wave forms to the horizontal plates. The application of, such wave forms to the deflection plates of an oscillograph produce a multiline sweep pattern in which the individual lines of the pattern are horizontal and are separated from each other by distances corresponding to the progressive reduction in amplitude of the constant voltage portions of the complex wave. However, extreme difliculties have been encountered when attempting to generate a complex wave form of the foregoing type, since the problems relating to the generation of square wave forms are involved. For example, the wave tends to overshoot when an abrupt change from one constant voltage to the next constant voltage of a lower amplitude is attempted, while difliculties have also arisen when endeavoring to cause such abrupt changes in voltageto occur at a high rate of speed. In view of these imperfections the sweep lines of the patterns produced in the foregoing manner are distorted, especially at the beinning of each horizontal line. The latter re sult is particularly disadvantageous, since in practically all applications of multi-linesweep patterns, it is necessary that the individual sweep lines be undistorted and linear at the beginning thereof.

It is therefore an object of the present invention to provide a novel method for generating a horizontal multi-line sweep pattern.

Another object is to provide novel means for generating horizontal multi-line sweep pattern.

Another object is to provide means responsiveto saw-tooth wave form; for producing a horizontal multl-line sweep pattern on an oscilloraph.

Another object is to provide a sweep circuit for applying saw-tooth wave forms to the deflection plates of an oscillograph, with means applying the wave forms to the horizontal deflection plates at a. frequency a number of times greater than the frequency of the saw-tooth wave forms applied to the vertical deflection plates equal to a number of sweep lines desired, while also including means for producing each sweep line in such a manner during a. certain period,

that the voltage applied to the vertical deflection plates during such period is substantially constant.

Still another object of the present invention is to provide a novel sweep circuit for producing a multi line sweep pattern on an oscillograph which includes means applying saw-tooth wave forms to the horizontal deflection plates of they oscillograph at a frequency a number of times greater than the frequency of the saw-tooth wave forms applied to the vertical deflection plates that is equal to the number of sweep lines desired, with means limiting the linearly varying voltage of each of the saw-tooth wave forms applied to the horizontal plates so that the sweep lines are produced during a period of time when substantially constant voltage is applied to the vertical deflection plates.

Still another object is to provide a sweep circult of the above character including mean responsive to a certain voltage value of the sawtooth wave forms applied to the horizontal plates for maintaining each wave form at a constant voltage value following said certain volta e for reducing the portion of each wave form that is capable oi producing a sweep line whereby each 3 sweep line is generated during a period of time wherein substantially constant voltage is applied to the vertical deflection plates.

Other objects and features of the invention will appear more fully from the following detailed description when considered in connection with the accompanying drawing which discloses one embodiment of the invention. It is to be elfpressly understood, however, that the drawing is designed for purposes of illustration only and not as a definition of the limits of the invention, reference for the latter purpose being had to the appended claims.

In the drawing, wherein similar reference characters denote similar elements throughout the several views:

. 4 applied to the horizontal deflection plates from generator III in order to generate each sweep line during a period of time during which negligible progress takes place in the linearly progressive portion of the wave form applied to the vertical deflection plates. As shown in Fig. 1, such means comprises limiter circuit I! which functions to limit the saw tooth waveforms of generator l Fig. 1 is a block diagram of a sweep circuit embodying the principles of the present invention;

Fig.- 2 shows the type of wave form applied to the horizontal deflection plates of the oscillograph disclosed in Fig. 1;

Fig. 3 shows a type of wave form applied to the vertical deflection plates of the oscillograph disclosed in Fi 1;

Fig. 4 is a schematic showing of the limiter circuit disclosed in Fig. l, and

Fig. 5 is a diagrammatic illustration of the sweep pattern'produced by the circuit shown in Fig. l.

With reference more particularly to Fig, 1 of the drawing, a sweep circuit for producing a horizontal multi-line sweep pattern is disclosed therein including a pair of saw-tooth wave generators I n and II of conventional construction. Generator I 0 is adapted to produce saw-tooth wave forms in accordance with a synchronizing source, such as a source of equally spaced electrical impulses, applied thereto from input termina1 l2. Generator II is likewise adapted to generate saw-tooth wave form in response to application of the synchronizing source from terminal l2; however, the frequency of the sawtooth wave output of generator II is adapted to be a certain number of'times less than the frequency of the output of generator III that is equal to the number of sweep lines that is desired in the pattern. In order to accomplish the foregoing, a suitable frequency divider I3 is positioned between input terminal I2 and saw-tooth wave generator II in order to reduce the frequency of the synchronizing source a sufllcient amount to cause operation'of generator H in the'manner noted heretofore. Frequency divider l3 may be of conventional construction, such as a frequen-- cy divider comprising a plurality of electronic counter circuits of the scale-of-two type for producing an output pulse upon application of every certain number of input pulses thereto from terminal l2. The output of generator in is fed to horizontal deflection plates l1 and is of oscillograph 16, while the saw-tooth wave forms from generator I 0 are applied to the vertical deflection plates I1 and I8. It is to be understood that the terms vertical and horizontal are relative and may be interchanged without change in results.

As stated heretofore, it is one of the objects of the present invention to provide a sweep circuit having novel means which operates to produce a pattern on oscillograph l6, which includes a plurality of horizontal sweep lines,'upon application of the outputs of saw-tooth wave generators i0 and II. More particularly, such means functions to reduce or limit the linearly increasmg voltage portion of each saw-tooth wave form .in a manner noted above and to apply the resultant wave forms to horizontal deflection plates l1. and I8. Limiter circuit is may be constructed in numerous ways to limit the output of saw-tooth wave generator III; as shown in Fig. 4 for example, the circuit may include a diode vacuum tube 20 which is normally in a non-conducting state but which is biased in such a manner, by means of resistance 2| and bias supply 22, as to be rendered conducting when each wave of the saw-tooth voltage rises to a certain potential to thus maintain the remaining portion of the saw tooth wave, which normally linearly increases, at constant voltage. The output of limiter circuit i9 is shown in Fig. 2, It can be readily seen from this figure that the voltage of each saw-tooth wave form linearly increases from zero potential until point a is reached, at which instant limiter circuit l9 functions to maintain the remaining portion of each wave at constant voltage.

Operation of the sweep circuit disclosed in Fig. 1 may be more readily understood with reference to Fig. 2, when considered in connection with Fig. 3 of the drawing which latter discloses the voltage applied to the vertical deflection plates 14 and It. From Figs. 2 and 3 it can be readily seen that the output of generator 10 is at a frequency four times greater than the frequency of the saw-tooth wave forms produced at generator II, in order to produce a sweep pattern having four horizontal lines. It is to be expressly under- 0 stood, however, that frequency divider I: may be liU adjusted to reduce the frequency of generator II any desired amount, with respect to generator I 0, to thus obtain any desired number of sweep lines on the oscillograph pattern. Also, it can'be readily seen from Figs. 2 and 3 that the saw-tooth wave forms applied to the horizontal and vertical deflection plates are in synchronism with each other, with the above mentioned frequency ratio. The first sweep line of the pattern is generated when the voltage of the first wave form shown in Fig. 2 linearly increases from zero potential to a certain value designated at point a, during which time negligible yariation takes place in the voltage applied to deflection plates I l and I5 since the saw-tooth wave shown in Fig. 3 has propagated for a very short period of time with respect to the complete cycle thereof. When the first wave form of Fig. 2 reaches point a, limiter circuit l8 functions to maintain the remaining period of the wave at constant voltage until the wave is terminated. As shown in Fig. 5, the foregoing produces sweep line b which is substantially horizontal. Sweep line b is generated during the period c of linearly increasing voltage of the first wave form shown in Fig. 2. The period d of constant voltage across the horizontal deflection plates permits production of a vertical line extending downwardly from the end of sweep b during period d, while the abrupt drop to zero potential, to terminate the wave form. causes the cathode ray beam to move to a position suitable for the initiation of the next sweep line. During propagation of the first wave, the sawtooth wave shown in Fig. 3 propagates in synchronism therewith, to thus apply a linearly increasing beam-depressing potential to the vertical deflection plates so that the next sweep line a. generated during the period of linearly increasing voltage c' of the second wave form of Fig. 2, occupies a position below the sweep line b. As the 2d. id-Md 4th wave forms shown in Fig. 2 propagate. sweep lines b, i and g are produced on the screen of oscillograph l6, as shown in Fig. 5. Since substantially constant voltages are applied to vertical deflection plates II and it during the periods 0 of linearly increasing voltage across the horizontal deflection plates, the-sweep lines generated by the latter are substantially horizontal. When pulses are appliedto the vertical deflection plates in synchronism" with the wave forms shown in Fig. 2, pulse indications are produced on the sweep lines b, e, 1 ii it" that are at right angles thereto, as shown in Fig. 5.

The sweep lines produced in accordance with the principles of the present invention may be caused to occupy substantially true horizontal position, by increasing the period d, of constant voltage, of each of the wave forms with respect to the period c, of linearly increasing voltage, shown in Fig. 2. Also. if desired. the sweep lines may be caused to deviate from the substantially true horizontal position by increasing the period 0 while decreasing a period of constant voltage (1.

There is thus provided by the present invention novel method and means for producing a horizontal multi-line sweep pattern on an oscillograph. Such means employs the application of saw-tooth wave forms and thereby produces a pattern having undistorted sweep lines since sawtooth wave forms may be readily generated. In order to generate a horizontal multi-line sweep pattern by utilization of saw-tooth wave forms, means are provided herein for reducing the linearly increasing voltage portion of the saw-tooth wave forms applied to the horizontal deflection plates, thus decreasing the portion of each sawtooth wave form which produces a sweep line. so that the propagation of the saw-tooth wave form, of a less frequency, applied to the vertical deflection plates, is very slight with respect to the complete cycle of such wave. to thereby apply substantially constant voltage to the vertical de- {lection plates during generation of each sweep ine.

Although only one embodiment of the invention has been disclosed and described in detail herein, it is to be expressly'understood that various changes and substitutions may be made therein without departing from the spirit of the invention as well understood by those skilled in the art. Reference therefore will be had to the appended claims as a definition of the limits of the invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

l. The method of generating a horizontal multi-line sweep pattern on an oscillograph which comprises applying lineal saw-tooth wave forms to the vertical deflection plates of the oscillograph, applying lineal saw-tooth wave forms to the horizontal deflection plates at a frequency a number of times greater than the frequency of the saw-tooth wave forms applied to said vertical plates and equal to the number of sweep lines desired, and limiting the linearly increasing voltage portion of each of the wave forms applied to the horizontal deflection plates whereby s eep lines are produced on. the oscillograph during a period of time when but a small fraction of the variation in voltage across the vertical deflection plates takes place.

2. The method of generating a horizontal multi-line sweep pattern on van oscillograph which I comprises producing a first source of saw-tooth wave forms each having a linearly varying voltage portion, producing a second source of saw-tooth v wave forms each having a linearly varying voltage portion at a frequency a number of times greater than the frequency of said first source that is equal to the number of sweep lines de-' the complete period of each wave, and applying the saw-tooth wave forms from the second'source to the horizontal deflection plates of the oscillograph whereby the sweep lines are produced dur ing periods of time wherein a substantially negligible variation takes place in the voltage applied to the vertical deflection plates.

3. The method of producing a horizontal multi-line sweep pattern on an oscillograph which comprises generating a first source of saw-tooth wave forms, each having a linearly varying voltage portion, producing a second source of saw-' tooth voltage forms each having a linearly vary- (ill ing voltage portion at a frequency a number of times greater than the frequency of said first source that is equal to the number of sweep lines desired, applying said first source of 'said sawtooth wave forms to the vertical deflection plates of the oscillograph, limiting the output of the saw-tooth wave forms from said second source for ti-line sweep pattern on. an oscillograph which comprises producing a first source of saw-tooth wave forms having a linearly varying portion, providing a second sourceof saw-tooth wave forms having a linearly varying portion at a frequency a number of times greater than the fre- Y quency of said first source that is equal to the number of sweep lines desired, applying said first source of said saw-tooth wave forms to the vertical deflection plates of the oscillograph, passing the output of said second source through a limiter circuit for limiting the larger portion of each wave form to a substantially constant voltage and permitting substantially the entire remaining and smaller portion to vary substantially linearly, whereby the linearly varying voltage portion of each wave comprises a substantially short period ith respect to the complete period of each wave, and applying the output of the limiter circuit to the horizontal deflection plates of the oscillograph for producing horizontal sweep lines thereon during a period of time that is comparatively short with respect to the complete period of the saw-tooth wave forms applied'to the vertical deflection plates whereby the voltage applied to the vertical deflection plates can vary 7 only slightly during the period of generation of each sweep line.

5. A method of generating a. horizontal multi-line sweep pattern on an oscillograph which comprises applying saw-tooth wave forms to the vertical deflection plates of the oscillograph, simultaneously applying other wave forms to the horizontal deflection plates of the oscillograph at a, frequency a number of times greater than the frequency of said saw tooth wave forms equal to the number of sweep lines desired, the said other wave forms applied to the horizontal deflection plates each having a portion of linearly increasing voltage comprising a short portion of the cycle with substantially the entire remaining larger portion of constant voltage, and causing the linearly increasing voltage portions of each wave to produce a sweep line on the oscillograph, with the voltage applied to the vertical deflection plates being substantially constant throughout generation of each sweep line.

6. A method of generating a multi-line sweep pattern on an oscillograph which comprises producing a source of wave forms each of which comprise a portion having linearly varying voltage. applying said wave forms at a first frequency to the vertical deflection plates of the oscillograph, simultaneously applying said wave forms at a frequency a number of times greater than said first frequency equal to the number of sweep lines desired to the horizontal deflection plates of the oscillograph, and reducing the duration of the linearly varying voltage portion of the wave forms applied to the horizontal plates to a small portion of the cycle of said wave for generating sweep lines during a period wherein substantially negligible variation takes place in the voltage applied to the vertical deflection plates.

7. A circuit for generating a horizontal multiline sweep pattern on an oscillograph comprising means applying saw-tooth wave forms each having a, linearly varying voltage portion to one pair of deflection plates of the oscillograph, means applying saw-tooth wave forms each having a linearly varying voltage portion to the other pair of deflection plates at a frequency a number of times greater than the frequency of the saw tooth wave forms applied to said one pair that is equal to the number of sweep lines desired, and means limiting the linearly varying voltage portion of each of the saw-tooth wave forms applied to said other pair of deflection plates to a small portion of the wave cycle and maintaining the voltage constant for substantially the entire remaining portion of the cycle, whereby sweep lines are produced each during a small portion of the lineal portion of said first wave.

8. A circuit for generating a. horizontal multiline sweep pattern on an oscillograph comprising a first source of saw-tooth wave forms each having a linearly varying voltage portion, a second source of saw-tooth wave forms each having a linearly varying voltage portion and of a frequency a number of times greater than the frequency of said first source that is equal to the number of sweep lines desired, means applying said first source to the vertical deflection plates of the oscillograph, means maintaining a continuous and greater portion of each saw-tooth wave form of said second source at constant voltage whereby the remaining linearly increasing voltage portion of each wave form comprises a short period of time with respect to the complete period of each wave, and means applying the saw-tooth wave forms of said second source to the horizontal deflection plates or the oscillograph whereby the sweep lines are produced during periods or time wherein negligible variation takes place in the voltage applied to said vertical deflection plates.

9. A circuit for generating a horizontal multiline sweep pattern on an oscillograph comprising a first source of saw-tooth wave forms each having a linearly varying voltage portion, a secand source of saw-tooth wave forms each having a linearly v ryin voltage portion and of a frequency a number of times greater than the frequency of said first source that is equal to the number of sweep lines desired, means applying said first source to the vertical deflection plates of the oscillograph, means limiting the output of said second source of saw-tooth wave forms for limiting the linearly varying voltage portions thereof, and means applying the limited wave forms to the horizontal deflection plates of the oscillograph for applying a linearly increasing voltage thereto during a period of time wherein substantially constant voltages are applied to said vertical deflection plates.

10. A circuit for generating a horizontal multi-line sweep pattern on an oscillograph comprising a first source of saw-tooth wave forms each having a linearly varying voltage portion, a second source of saw-tooth wave forms each having a linearly varying voltage portion and of a irequency a number of times greater than the irequency of said first source that is equal to the number of sweep lines desired, means applying said first source to the vertical deflection plates of the esciliograph, a limiter circuit for maintaining a continuous and greater portion of each wave forms from said second source at constant voltage whereby the entire remaining linearly varying voltage portion of each wave comprises a substantially short period with respect to the complete period of each wave, and means applying the output of said limiter circuit to the hori zontal deflection plates of the oscillograph for applying linearly increasing voltages thereto during a period of time that is substantially short with respect to the complete period of the sawtooth wave forms applied to said vertical deflection plates whereby negligible variation takes place in the voltage applied to said vertical de iiection plats during the period of generation of each sweep line.

11. A circuit for generating a horizontal multi-line sweep pattern on an oscillograph comprising means applying saw-tooth wave forms to the vertical deflection plates of the oscillograph, means for simultaneously applying other wave forms to the horizontal deflection plates of said oscillograph at a frequency a number of times greawr than the frequency of said saw-tooth wave forms equal to the number of sweep linesdesired, said other wave forms having a portion of linearly increasing voltage followed by a portion of constant voltage with the portion of linearly increasing voltage comprising a short portion of the cycle of each wave with respect to the portion of constant voltage, and said linearly increasing voltage portions producing a sweep line on the osciliograph during a period of time wherein negligible progress takes place in the linearly progressive portion of the wave form applied to said vertical deflection plates.

HARDID' LIFSCHUTZ.

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