US2496912A

US2496912A - Device for integrating a variable quantity

Info

Publication number: US2496912A
Application number: US668441A
Authority: US
Inventors: Igor E Grosdoff
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1946-05-09
Filing date: 1946-05-09
Publication date: 1950-02-07
Anticipated expiration: 1967-02-07

Description

Feb. 7, 1950 i. E. GROSDOFF 2,496,912

DEVICE FOR INTEGRATING A VARIABLE QUANTITY I Filed May 9, 1946 nu A; W

W E k 1 JA jJIi r R IN! EN TOR.

w t k N [5 02' E. 6211/1/01? E R Q BY 0&2 A 1 M Q gi s. c A TTl/RNEI Patented Feb. 7, 1950 oavrcr: FOR INTEGRATING A vAnrAnLa QUANTITY Igor E. Grosdoii, Princeton, N. 1., assignor to Radio Corporation of America, a corporation of Delaware Application May 9, 1948, Serial No. 668,441

3 Claims. (Cl. 171-95) This invention relates to devices for integrating a variable quantity such as the volume of sound, the intensity of light or any other type of variable which may be made to produce an electrical potential which changes in accordance with the value of such variable.

An important use of the device of the present invention is for the integration of the applause accorded a speaker or the integration of the noise incident to some other event. In accomplishing this result, the noise is picked up by a microphone which generates an alternating potential proportional in amplitude to the volume of the sound- This potential is amplified, detected and applied to an oscillation generator which delivers an alternating potential having a frequency which varies in accordance with the volume of the sound. The cycles of this variable frequency potential are counted and indicated either continuously or over a predetermined time interval by an electronic counter. The number of such cycles indicated during any given time interval varies as the volume of sound. Likewise the rapidity at which the cycles are counted and indicated in the case of continuous counting also varies as the volume of the sound. Thus when the volume of the sound is relatively low, the frequency of the counted cycles has a correspondingly low value and vice versa.

Various means may be provided for limiting the counting of the cycles to a predetermined time interval following the beginning o1 the noise. Perhaps the simplest of such means would be a timer or a time delay relay which functions (1) to open a gate between the variable frequency oscillator and counter in response to the beginning of the noise and (2) to close such gate at a predetermined time after it is opened. Obviously the gate may also be opened in response to the beginning of the noise and closed inresponse to the termination of the noise.

What has been said with respect to the integration of sound is equally applicable to the light picked up by a photo cell located to receive the light admitted through a camera shutter, for example, or to any other variable which is capable of producing an electrical potential varying in accordance with the value of the variable.

Important objects of the present invention are (1) the provision of an improved means for integrating a variable quantit and providing an instantaneous indication of the integrated quantity, (2) the provision of means for integrating a variable quantity over a p d t r in d e i terval, and (3) the provision 01' an improved device and method of operation for deriving and indicating the true integral of a variable quantity in terms of a potential having a frequency which is in direct proportion to the value of the variable.

The invention is better understood from the following description considered in connection with the accompanying drawing and its scope is indicated by the appended claims.

The single figure of the drawing is for the most part a wiring diagram of the improved integrating device, parts which are old and well known being mostly indicated by boxes bearing legends indicating their contents.

Referring to the drawing, the integrating device includes a pick-up device it which ma be a microphone, a photo electric unit or any other device capable of converting variations of a variable to corresponding variations of an electrical potential.

The electrical potential thus modulated by the variable quantity is amplified by an amplifier II and detected by a detector illustrated as including a diode l2, a filter network i3 and an output resistor II.

The detected potential is applied through a lead ii to the input of an oscillator which may be like that disclosed by U. S. Patent 2,321,269. This oscillator functions to make available at its output lead IS a potential having a frequency which is directly proportional to the detected amplitude or level of the variable quantity picked up by the device ill.

The basic element of the oscillator is a fourstep series-capacitor ladder network I! driven by a pentode i8. The network ll includes (1) resistors i9, 2| and 22 which are grounded at their low voltage terminals and (2) a resistor 20 which is connected to ground through a triode 23 and a resistor 24. With the resistor 20 open circuited by the triode 23, the fundamental frequency of the oscillator is 2000 cycles and, with the resistor 20 grounded, it is somewhat over 4000 cycles. Values of resistance between zero and infinity in series with the resistor 20 will produce frequencies between these limits. The actual value of this series resistance is of course determined by the amplitude of the detected potential applied to the input of the tube 23.

The resistors 26 and 25 form a center tap 58 on the 3 supply voltage. The triode 21 functions as an anode resistor for the triode 23. Thus if the triode 23 is at zero bias, it draws full anode current through the triode 21 and the two tubes form a low resistance to ground. As negative bias is applied to the grid of the triode 23 through the phase reverser 28 the equivalent plate resistance of the tube 23 is increased and the output frequency at the oscillator output lead It is lowered in direct proportion to such increase.

The output potential of the oscillator is applied to the second grid of a mixer tube 25. To the first grid of the tube 29 may be applied a square topped timing wave produced by a timing device 30 which is connected to the detector output lead i so as to be actuated in response to the beginning of a detected variable-quantityresponsive potential. As a result, there is applied through the lead 3] a potential which (1) has frequencies determined by the values of the integrated variable quantity and (2) is restricted to a predetermined time interval by the wave delivered from the timer 50 but only when a switch 32 is in its closed position.

This potential, having its frequency modulated in accordance with successive values of the variable quantity, is applied through a wave shaping or impulse generating device 55 and a lead 54 to the input of an electronic counter which may include a plurality of trigger circuit units 35 to 44. Impulse generating device 31 produces, in lead 34, a succession of negative pulses, one for each cycle of the substantially sinusoidal output voltage of the oscillator appearing at output terminal l6.

Each of these trigger circuits is of the type where in a pair of triode elements each has its anode coupled to the grid of the other so that stable conditions are established only when current conductivity is in one or the other of the triode elements. Current conductivity is transferred from one to the other of the triodes (1) in response to a negative pulse applied to the common anode terminal. (2) in response to a positive pulse applied to the grid of a triode element which is not conducting current, or (3) in response to the application of a negative pulse to the grid of a triode which is conducting current.

Thus the trigger circuit 35, for example, 1) has its anodes connected to the +13 lead through a common resistor and through individual resistors 46 and 41, (2) has a cathode which is grounded and common to both triode elements, (3) has its anodes cross connected to its grids through a capacitor 48 which is shunted by a re-- sistor 49 and a capacitor so which is shunted by a resistor 5| and (4) has negative bias potential applied to its grids either directly from a negative bias lead 54, which is connected to a suitable bias potential source (not shown), or from the lead 54 through a reset switch 53 and a reset lead 52. For indicating when current conductivity is in the left hand triode element, an indicator 55 such as a neon lamp is connected across the resistor 45.

The other trigger circuits 3. to 44 are like the trigger circuit 35 and therefore need not be described in detail.

By opening and closing the reset switch 53, there is established a standby condition of the counter with current conductivity in the right hand triodes of all the trigger circuits. Negative pulses. one for each cycle of the oscillator output potential, are applied to the common anode terminal of the trigger circuit 35.

The first of these negative pulses transfers current conductivity to the left hand side of the trigger circuit 35, thereby lighting the lamp 55 and indicating a count of one cycle. The second pulse transfers current conductivity to the right hand triode of the trigger circuit 35 and produces a negative pulse which is transmitted through a capacitor 55 to the common anode terminal of the trigger circuit 35 and functions to transfer current conductivity to the left hand triode, this trigger circuit thereby lighting an indicating lamp 51. How additional negative pulses applied to the lead 34 are indicated by the counter is too well known to require further explanation.

It is apparent that the count is made in the binary numerical system, so that the lamps lighted at the end of the count indicate different powers of two, which must be added together to derive the equivalent value in the decimal system. Thus, the lamp 55 indicates 1 cycle, the lamp 5! indicates 2 cycles, the third lamp 4 cycles. This number of cycles is represented by the binary number Ill and by the decimal number I.

By providing a somewhat different indicating system, the counter may be made to indicate the total number of cycles directly in the decimal system.

By way of example, the decimal counter may be 'of the type disclosed in the copending application of Igor E. Grosdoif, Serial No. 580,446, filing date March 1, 1945, entitled Improvement in electron counter," and assigned to the same assignee as the instant application.

What the invention provides is an integrating device which functions to integrate a variable quantity and to provide an instantaneous indication of the integrated variable quantity.

I claim as my invention:

1. In combination. an oscillation generator continuously producing a substantially sinusoidal alternating output voltage the frequency of which may be varied, means responsive to the instantaneous value of a sporadic variable quantity for varying the frequency of said voltage in proportion to such instantaneous value, means coupled to said voltage output for producing therefrom a voltage pulse for each cycle of said voltage, means for counting and indicating the total number of said pulses, and means responsive to the initial appearance of said variable quantity for limiting the counting of the number of said pulses to a predetermined time lnterval immediately following said appearance.

2. In combination. a pick-up device operable in response to a variable quantity to produce a potential having an amplitude proportional to the instantaneous value of said quantity, means for detecting and rectifying said potential, an oscillation generator continuously producing a cyclically-recurring continuously-varyin alternating output voltage the frequency of which may be varied, means for varying the output frequency of said generator in accordance with the amplitude of said detected and rectified potential, and means for counting and indicating the total number of cycles of said generator output frequency during a predetermined time interval.

3. In combination. a pick-up device operable in response to a sporadic variable quantity to produce a potential having an amplitude proportional to the instantaneous value of said quantity, means for detecting and rectifying said potential, an oscillation generator continuously producing a substantially sinusoidal alternating output voltage the frequency of which may be varied, means for varying the output frequency of said generator in accordance with the amplitude of said detected and rectified potential, means for counting and indicating the total number of cycles of said generator output frequency, and timing means responsive to the initial appearance of said variable quantity for limiting to a predetermined time interval immediately thereafter the 5 supply of said generator output to said counting Number and indicating means. 2,341,040 IGOR E. GROSDOFF. 2,353,203 2,384,792 REFERENCES CITED 5 2 337 49 The following references are of record in the 230559 file of this patent: 2330439 2,438,425 UNITED STATES PATENTS Number Name Date 10 1,809,683 Fitzgerald June 9,1931 Number 2,309,749 Baughman Feb. 2, 1943 144,131 2,325,927 Wilbur Aug. 3, 1943 Name Date Hathaway Feb. 8, 1944 Usselman July 11, 1944 Brown Sept. 18, 1945 Cornelius Oct. 23, 1945 Miller Aug. 13, 1946 Peterson Nov. 4, 1947 Vance Mar. 23, 1948 FOREIGN PATENTS Country Date Austria Dec. 27, 1935