US3568182A

US3568182A - Method for producing code members

Info

Publication number: US3568182A
Application number: US513478A
Authority: US
Inventors: Edward M Jones
Original assignee: DH Baldwin Co
Current assignee: BPO ACQUISITION CORP; Baldwin Piano and Organ Co; DH Baldwin Co
Priority date: 1962-06-18
Filing date: 1965-12-13
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02

Abstract

A method for recording an image on a photosensitive surface rotating on a turntable in which the area of the image is varied responsive to the numerical value of a digitally recorded tape transported in synchronism with the rotation of the turntable.

Description

United States Patent [1113,568,182

[72] lnventor Edward M. Jones 2,678,254 /1954 Schenck 346/33opt Cincinnati, Ohio 2,760,404 8/1956 King 88/24 [21] Appl. No. 513,478 2,897,710 8/1959 Lemoine 84/128 [22] Filed Dec. 13, 1965 3,040,322 6/1962 Mahaney et al. 346/3 pt Division of Ser. No. 203,354, June 18, 1962, 3,199,111 8/1965 Jennings et al. 340/347 Patent No. 3,235,878. 3,344,418 9/1967 Jones 340/347 1 Patented 1971 2,890,288 6/1959 Newman 179/1002 [73] Assignee D. H. Baldwin Company 3,037,090 5/1962 Bouzemburg 179/1002 Cincinnati, Ohio 3,072,753 1/1963 Goldberg 179/ 100.2

Primary Examiner-Maynard R. Wilbur 54 METHOD FOR PRODUCING CODE MEMBERS ASSiSM'1tEmmin@r Gary Edwards 6 Claims, 14 Drawing Figs AztorneysBurmerster, Palmatler & Hamby and William H.

B e n' [52] us. Cl 340/347 r u [51] .....H03k 13/04 340/347 (da);346/33,1, 33 (opt. seis), (inquired); 84/1.18,1.28;274/4l.62, 46; 179/1003; 178/6.7,

36 ABSTRACT: A method for recording an image on a photosen- [56] References Cited sitive surface rotating on a turntable in which the area of the image is varied responsive to the numerical value of a digitally UNITED STATES PATENTS recorded tape transported in synchronism with the rotation of 662,020 1 1/1900 Pollak et a1. 178/15 the turntable.

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PATENTED HAR 219w SHEET 1 0F 7 mimgnm 2197! 3568.182

sum u or 7 J8 FIE.EJ/) 8 i i k j i PATENTED HAR 219m sum 1 or 7 METHOD FOR PRODUCING CODE MEMBERS This application is a division of application Ser. No. 203,354, filed Inn. 18, 1962 now'U.S. Pat. No. 3,235,878. The present invention relates to methods for producing pitch discs for electrical organs and code discs for analogue to digital encoders.

Code discs are well known for encoding analogue informa- I tion into binary digits. Such code discs have a plurality of annular tracks of opaque and transparent sectors coaxially disposed about the center of the code disc. An analogue to digital encoder employing such a disc has a light source disposed adjacent to one side of the code disc, and a light responsive cell confronting each of the tracks of the code disc on the other side of the code disc. The code disc is mounted on a shaft, and the angular position of the shaft may be read in digital form by periodically sampling the response of the light responsive cells. US. Pat. No. 3,023 ,406- entitled Optical Encoder issued Feb. 27, 1962, of the present inventor, illustrates such an optical encoder.

Pitch discs for use in generating tones of a photoelectric organ are of similar construction to the code discs of an optical encoder. Voice discs are similar except that the transparent areas are eithervaried as to opacity, or varied in area.

The present inventors US. Pat. No. 3,023,657, dated Mar. 6, 1962, entitled Photoelectric Musical Instruments and the Like, discloses a photoelectric organ employing such a pitch disc and voice disc. Both the pitch disc and the voice disc may be produced according to the present invention.

Both pitch discs and code discs have been produced in accordance with the teachings of US. Pat No. 2,924,138 of the present inventor, dated Feb. 9, 1960, and entitled Electronic Synchronizing System for Producing Pitch Discs and the Like. In accordance with the teachings of this patent, a photosensitive layer is rotated on the surface of a turntable rotating at a rate synchronized with a pulse generator, and the pulse generator is utilized to periodically flash a lamp focused on a small area of the turntable. In this manner, a plurality of tracks may be exposed on the photosensitive surface containing exposed areas which are a multipleof the number of pulses of the pulse generator for each rotation of the turntable. Code discs for analogue to digital converters may be directly produced by this equipment. Voice discs for electric organs, however, require a means to vary the intensity of light impinging upon the photosensitive surface, during the period of a light flash in accordance with the desired waveform to be impressed upon the photosensitive surface. For the production of voice discs, a harmonic synthesizer is sued to generate the desired waveforms and to control the intensity of the light falling on the photosensitive surface during each pulse of the pulse generator.

The method of producing code discs and pitch discs disclosed in US. Pat. No. 2,924,138, has three principal disadvantages. First, the number of light pulses per revolution of the turntable is limited to a multiple of the pulses from the synchronizing pulse generator. As a result, it has proven difficult to produce code discs for analogue to digital encoders which directly read in terms of trigonometric functions, since the spacing between the transparent sectors of such discs varies in accordance with the trigonometric function used in encoding the angular position of the disc. Second, the harmonic synthesizer must itself generate the waveforms being impressed upon pitch discs for musical instruments, and the tones which may be generated by such pitch discs are therefore limited by the ability of the harmonic synthesizer to generate these tones. Third, the output of the harmonic synthesizer is utilized to vary the intensity of the light source, and hence produce a variable intensity photographic disc. Photoelectric sound systems operating on variable density recordings have not proven to be as satisfactory as variable area recordings.

U.S. Pat. No. 2,760,404 to King discloses a device for exposing sectors of a photosensitive surface on a turntable in which a tape transport mechanism is operated in synchronism with the turntable and indicia on tape carried by the transport mechanism are utilized to control the exposure of these sectors. By synchronizing a tape transport mechanism with the turntable, the indicia on the tape may be arranged to provide any spacing desired between light flashes focused on sectors of the photosensitive film. It is difficult, however, to synchronize the motion of the turntable with the translation of the tape transport mechanism with the accuracy required for the production of code discs and pitch discs, and it is an object of the present invention to provide a device for producing such discs in which a light source is controlled by a tape with an improved means for synchronizing the movement of the member carrying the photosensitive film and the tape transport mechanism.

It is also an object of the present .invention to provide a machine'for recording waveforms on code members, such as pitch discs, in which electrical signals generated from a tape represent the waveforms to be recorded and are utilized for control of the recorder. More specifically,it is an object of the present invention to provide av machine for recording waveforms on members, such as pitch discs, in which a plurality of electrical signals are generated from a tape representing digitally the magnitude of the waveform, and these digital signals are converted into an analogue signal for controlling the recording of the member. I

It is afurther object of the present invention to provide a machine for producing variable area photoelectric pitch discs.

' It is a further object of the present invention to provide a method for recording information on members generated from tape carrying digital indicia.

' 'These and further objects of the present invention will .become readily apparent to those skilled in the art from the following specification, particularly when viewed in the light of the drawings, in which:

FIG. 1 is a schematic electrical diagram illustrating a device for recording indicia on a member from digital electrical signals derived from a tape;

FIG. 2 is a fragmentary schematic view of a magnetic tape for use in the machine of FIG. 1 illustrating the location of recorded indicia thereon;

FIG. 3 is a schematic diagram illustrating the polarization vectors in a portion of the tape of FIG. 2;

FIG. 4 is a block schematic diagram of the digital to analogue computer illustrated in FIG. 1;

FIG. 5 is a schematic electrical circuit diagram of the digital to analogue converter illustrated in FIG. 1, FIGS. 5a and 5b illustrating details thereof;

FIG. 6 is a block schematic diagram of the error signal generator illustrated in the machine of FIG. 1;

FIG. 7 is a schematic electrical circuit diagram of a portion of the error signal generator illustrated in block diagram in FIG. 6;

FIG. 8 contains a plurality of graphs illustrating the shape of electrical waves at various locations in the circuit illustrated in FIG. 7;

FIG. 9 is a fragmentary view illustrating a photoelectric machine for recording variable area indicia on a photographic member;

FIG. 10 is a sectional view of the machine illustrated in FIG. 9 taken along the line 10-10 thereof;

FIG. 11 is a fragmentary sectional view taken along the line 11-11 of FIG. 9; and

FIG. 12 is a fragmentary view illustrating a different form of shutter for use in the machine of FIG. 9.

FIG. 1 illustrates a turntable 20 which carries centrally thereof a disc 22 upon which indicia are to be recorded to form a code disc or a pitch disc. A recorder 24 confronts a portion of the disc 22 and is adapted to alter a characteristic of the disc in order to inscribe or place thereon the necessary indicia. The disc 22 may be a photographic sensitive film, and the recorder 24 may be the combination of a light source focused on the photosensitive film and a shutter for interrupting or varying the light falling upon the disc 22. The disc 22 may also be a magnetically polarizable plate, and the recorder 24 a recording head capable of aligning polarization vectors along desired axes, asis conventional iii magnetic recording.

The recorder 24 is controlled by a plurality of electrical signals generated from a tape 26 mounted on a tape transport mechanism 28. In the embodiment of FIG. 1, the tape 26 is a magnetic tape,and a plurality of magnetic reproducing

heads

30A, 30B, 30C, 30D, 30E and 30F confront the tape 26 along an axis normal to the longitudinal axis of the tape 26 and in close adjacency. Each of the recording heads is separately 6 connected to a digital to analogue converter 32 which converts the electrical signals separately generated by the reproducing heads to a single electrical signal appearing at the generating electricalsignals representingdigital values of .a

I particularfunction to be recordedon the disc 22, this generating means being enclosed within the dashed lines designated 36inI-IG. l. e I Afragment of the magnetic tape 26 is illustrated in FIG. 2,

and this tape is of the type which islconventionally used with computer equipment. It is first determined that the shape of the recorded indicia on thedisc 22 shall assume the form of a mathematical function, generally indicated as flx). A plurality of values for the function flx) maybe calculated for exposing aplurality of sectors of a coaxial track on the turntable, and the number of values which may beused is determined by the mechanical accuracy of the equipment including the accuracy with which the tape transport mechanism 28 is synchronized with the turntable 20.

FIGS. 2 and 3 illustrate a fragmentary portion of the tape 26 i indetail. The tape 26 has an elongated strip base 38 of nonmagnetic electrically insulating material, such as polyester plastic, and a coating 40 of ferromagnetic material is disposed on the base3,8.The coating 40 is capable of maintaining magnetic polarization, and aplurality of tracks designated 42, 44, 46, 48, 50 and 52 are disposed upon the tape 26 along parallel paths parallel to the axis of elongation of the tape. Eachof the tracks represents the area confronting a single reproducing head 30 for reproducing a signal from that track of the tape when the entire tape passes the playback head assembly 60.

Each track of the tape 26 contains a series of alternating indicia of two types, the indicia being the transitions of magnetic polarizations in opposite directions in the case of the magnetic tape 26. FIG. 3 shows the polarizations for the track 46. The

arrows 54 are polarized parallel to the track 46 in one direction, and the arrows 56 disposed between the arrows 54 :are polarized in the opposite direction. In this manner, the

reproducing head 30D produces an electrical signal of one 1 polarity for a transition after the arrows 4 and a signal of the opposite polarity for a transition after the arrows 56. It is apparent that all of the other tracks of the tape 26 are also polarized in the same manner, except the length of the arrows are different between the transitions.

The magnetictape 26 may be magnetically polarized as indicated, or in any other manner which is subject to calculation, directly from the output of an electronic computer. Most e such computersydirectly produce its output in the form of a magnetic tape which can be used as the tape 26. Thus, the calculated output of an electronic computer is directly useable 'with the equipment of FIG. 1.

The digitalto analogue converter 32 is illustrated as having input terminalsy58B, 58C, 58D, 585 and 58F. These terminals are connected to the reproducing heads 30B, 30C, 30D, 30B

and 30F, respectively, which are mounted in a common housing .to form a playback head assembly 60. The digital to analogue converter 32 has an output terminal 62 on which an analogue signal voltage is produced which is proportional to the digital value of the signals appearing on the input terminals. FIG. 4 illustrates in block diagram the circuit for the digital to analogue converter 32.

It will be noted in FIG. I that a radius changer 64 is indicated electrically connected to the output of a radius changer control 65 which is included in an assembly with the digital to analogue converter 32 and mechanically connected by an arm 66 to the recorder. It is the function of the radius changer 64 to move the recorder toward or away from the axis of the disc 22 in accordance with programming information appearing in the output of the radius changer control 65, and two

output terminals

68 and 70 are provided for that purpose. Track 52 of the tape 26 carries instructions for the radius changer 64, and the pickup head 30A detects the presence of an instruction signal, indicated at "72 in FIG. 2, on the tape 26 and transmits it to the input of a preamplifier 74A, illustrated in FIG. 4. The output of the preamplifier 74A is connected to the input of an undelayed signal amplifier 76A, and the output .of the undelayed amplifier76A is directly connected to a fullwave rectifier 78A. The output of the full-wave rectifier 78A is electrically connected through a gate circuit 80A and an in pulse amplifier 82A to the output terminal 68. The output of the undelayed signal amplifier 76A is also connected through a delay line 84A, a delayed signal amplifier 86A, a full-wave rectifier 88A, a gate 90A and an out pulse amplifier 92A to the output terminal 70. As statedabove the

outputterrninals

68 and 70 are electrically connected to the radius changer 64* and control its position. T; g

The gates 80A and 90A a re controlled by signals from the pickup head 30D. The picl t tlp head 30!) is connected to a preamplifier 74D through the ipputterminal 58D, and the output of the preamplifier MD is connected to the input of the undelayed amplifier 76D. The output'of the undelayed amplifier 76D is connected to the input of a full-wave rectifier 78D, and the output of the rectifier is connected to a resonator 94. The output of the resonator 94 is connected to a toggle and sampling pulse generator 96, and the output of the sampling pulse generator 96 is connected to the control input of both gates 80A and 90A.

The pickup head 30D is aligned with the track 46 of the tape 26, and each of the marks of this track, which correspond to the mark 72 of the track 52, generate an electrical pulse in the pickup head 30D, alternate ones of which are of opposite polarity as indicated in connection with the description of FIG. la. The pulses of both polarities are amplified by the preamplifier 74D and the undelayed signal amplifier 76D and impressed upon the input of the full-wave rectifier 78]). The rectifier 78D inverts the positive pulses generated by the pickup head 30D, and passes the negative pulses on to the resonator 94 substantially unchanged. The resonator 94 has the resonant frequency of 375 cycles per second, and the pulses of the track 46 or" the tape 26 are spaced to generate 375 cycles per second at the rate of transportation of the tape transport mechanism 28. As a result, small errors in the position of a single mark or the omission of a single mark of the track 46 will not appreciably affect the rate of the signal impressed upon the input of the toggle and sampling pulse generator 96.

If the mark 72 of the track 52 is aligned on an axis normal to the axis of the tape 26 with a mark of the track 46, which is the synchronizing track, then a pulse will be delivered from the rectifier 78A to the gate 80A simultaneously with a pulse from the toggle and sampling pulse generator 96 impressed on the control input of the gate 80A. The gate 80A is a coincident circuit, and will deliver a pulse to the in pulse amplifier 82A under these conditions, but will not deliver a pulse to the in pulse" amplifier unless the two inputs of the gate circuit 80A receive pulses at approximately the same time.

FIG. 2 shows the marks 72 representing magnetic polarization in the proper direction aligned with a mark on the track 46, and the result is that the in pulse" amplifier 82A will receive a pulse when this portion of the tape confronts the playback head assembly 68. it is also to be noted that a pulse 72A is illustrated in FlG. which is located between pulses of the synchronizing track 46. Under these circumstances, the gate 80A will not pass a pulse to the in pulse amplifier 82A. However, the delay line 84A will delay the pulse generated by the mark 72A generated by the playback head assembly 60, and the delayed pulse will be amplified by the delayed pulse amplifier 86A and rectified by the full-wave rectifier 88A. As a result, pulses will appear on the control input terminal of the gate 90A simultaneously with the pulse impressed on the input of the gate 90A from the full-wave rectifier 88A, thus resulting in a pulse in the output of the gate 90A which is impressed upon the out pulse amplifier 92A. The output from the out pulse" amplifier appears on the terminal 70, and this pulse results in the radius changer 64 moving the arm 66 in the direction to move the recorder 24 outwardly from the center of the disc 22. When a pulse appears in the output of the in pulse amplifier 82A, the resulting pulse impressed upon the radius changer 64 causes the arm 66 to move the recorder 24 in a direction toward the axis of the disc 22.

The radius changer 64 is diagrammatically illustrated in FIG. 1 and is an electromechanical device for positioning the arm 66. For example, the arm 66 may be the pivotal arm of a stepping relay which is driven one step in a first direction by each pulse from the in pulse amplifier 82A and is driven one step in the reverse direction by each pulse from the out pulse amplifier 92A. Since stepping relays and stepping motors suitable for performing this low speed function are well known in the art, as indicated by Section 5.39 of Control Engineers Handbook, John G. Truxal, Editor, McGraw-l-lill Book Co., Inc., 195 8, the radius changer structure will not be described in detail.

It is to be noted that the full-wave rectifiers 78A, 78D and 88A invert positive pulses impressed thereon but transmit the negative pulses impressed thereon without substantial alteration. As a result, negative pulses are in all cases impressed upon the input of the gate circuits 80A and 90A, and these gate circuits will have an output only if coincidence exists between the pulse on the gatecircuit input and on the control input of the gate circuits.

The resonator 94 has a Q which is sufficiently high to produce an output even if one of the marks of the synchronizing track 46 of the tape 26 is missing, or fails to generate a signal, but the Q of this circuit is not sufficiently high to cause appreciable phase shift due to spacing variation of the marks on the track 46 of the tape 26 which may be the result of variations of the rate of transport of the tape 26 during its recording operation.

The track 50 of the tape 26 produces electrical signals on the input 58B of the digital to analogue converter 32. Input 58B is electrically connected to a preamplifier 74B, and the output of the preamplifier 74B is electrically connected to an undelayed signal amplifier 7613. The output of the undelayed signal amplifier 76B is electrically connected to the input of a full-wave rectifier 78B and the output of the full-wave rectifier 78B is electrically connected to the input terminal of a gate 808.

The output of the undelayed signal amplifier 76B is also connected to the input of a delay line 8433,, and the output of the delay line 84B is electrically connected to a delayed signal amplifier 86B. The output of the delayed signal amplifier 86B is electrically connected to a full-wave rectifier 88B, and the output of the full-wave rectifier 88B is electrically connected to the input terminal of a gate 908. The gate 80B and the gate 90B have control input terminals which are electrically connected to the output of the toggle and sampling pulse generator 96.

In like manner, the track 48 of the tape 26 generates an electrical signal on the input terminal 58C of the digital to analogue converter 32. A preamplifier 74C is electrically connected to the input of'a delayed signal amplifier 86C. The output of the delayed signal amplifier 86C is connected to the input of a full-wave rectifier 88C, and the output of the fullwave rectifier 88C is connected to the input terminal of a gate 90C. 4

In like manner, track 44 of the tape 26 generates electrical pulses on the input terminal 58E of the'digital to analogue converter 32. The terminal 58E is electrically connected through a preamplifier 74E, and undelayed signal amplifier 76E, a full-wave rectifier 78E, to theinput terminal of a gate 80E. Also, the output of the undelayed signal amplifier 765 is electrically connected to a delay line 84E, a delayed signal amplifier 86E, a full-wave rectifier 88E, to the input terminal of a gate 90E. The gates 80B and 90E also have control input terminals which are connected to the output of the toggle and sampling pulse generator 96.

Further, the track 42 of the tape 26 generates electrical signals on the input terminal 58F of. the digital to analogue converter 32. A preamplifier 74F,.undelayed signal amplifier 76F full-wave rectifier 78F, and gate 80F are connected to the input terminal 58F. A delay line 84F is also connected to the output of the undelayed signal amplifier 76F, and a delayed signal amplifier 86F and full-wave rectifier 88F are connected between the delay line 84F and a gate 90F. The control input of the gate 90F is also connected to the output of the toggle and sampling pulse generator 96.

The electrical signals impressed upon the

input terminals

58B, 58C, 58E and 58F contain the digital input which is to be converted to an analogue electrical signal. The output of the gate 80B is connected to the input of a DC amplifier 94B, and

a capacitor 968 is connected from the input of the DC amplifier 948 to ground. The output of the amplifier 94B is connected to a resistor network 98.

In like manner, the output of the gate 90B is connected to the input of a DC amplifier 1008, and a capacitor 1028 is connected from the input of this amplifier to ground.

The output of the gate 80C is connected to the input of a DC amplifier 94C, and a capacitor 96C is connected between the input of the amplifier 94C and ground. The output of the gate 90C is connected tothe input of an amplifier 100C, and the input of the amplifier 100C is connected by a capacitor 102C to ground.

The output of the gate 80B is connected to the input of a DC amplifier 94E, and the input of the amplifier 94E is connected to ground through a capacitor 96E. In like manner, the output of the gate 90E is connected to the input of a DC amplifier 100E, and the input of the amplifier 100E is connected to ground through a capacitor 102E.

The output of the gate 80F is connected to the input of a DC amplifier 94F, and the input of the amplifier 94F is connected to ground through a capacitor 96F. Also, the output of the gate 90F is connected to the input of a DC amplifier 100F and a capacitor 102F is connected between the input of the DC amplifier 100F and ground. The output of the

DC amplifiers

94B, 1008, 94C, 100C, 94E, 100E, 94F and IMF are connected to the resistor network 98.

FIG. 5 illustrates in greater detail the electrical circuit of a portion of the digital to analogue converter circuit illustrated in FIG. 4 by block diagram including the resistor network 98, the full-

wave rectifiers

78B, 88B, 78C, 88C, 78E, 88E, 78F and 88F, and the intervening circuits, including the electrical circuit diagram for each of the gates 80B, 90B, 80C, 90C, 80E 90E, 80F and 90F. Also FIGS. 5a illustrates the circuit diagram for one of the full-wave rectifiers 88F. FIG. 5b illustrates the circuit for one of the DC amplifiers 100F.

It will be noted that each of the gate circuits utilizes a transistor 104 with a base 106 electrically connected 140 a resistor 108 to the toggle and sampling pulse generator 96. The input element 110 of the transistor 104 is electrically connected to the output terminal of the full-wave rectifier 88F, and the output terminal 112 is electrically connected to input of the DC amplifier 100E. The transistor 104 is a symmetrical transistor, which means that it will conduct equally wait in both directions. Asa result, the'negativ e pulse appearing at t the output of the full-wave rectifier 88 will charge the capacitor 1021- to the instantaneous negative potential of the pulse during the period in which a pulse is received from the toggle j and sampling pulse generator 96, or discharge the capacitor to this value. The other gate circuits designated 80A, 90A, 80B,

90B, 80C, 90C, 80E, 90E, and 80F operate in the same ;manner.

FIG. a illustrates one of the full-wave rectifiers 88F, although it is to be understood that the other full-wave rectifiers 78A,

88A

78B, 88B,

88A

88C, 78E, 8815, and 78F may be of identical construction. The purpose of the full-wave rectifiers is to invert positive pulses to negative pulses while transmitting the negative pulses substantially unaltered. In this manner, the positive and negative pulses from the tape 26 may both be utilized. The full-wave rectifier 88F employs three transistors 114,

116, and 118. The base 120 of the transistor 114 forms the input of the rectifier, and the collector 1220f the transitor 114 is connected to the negative terminal of a power source through a resistor 124. The emitter is connected to the positive terminal of a power source through a resistor 126. A balancing resistor 128 is connected in parallel with the resistor 126. The collector 122 of the transistor 114 is electrically connected to the base 130 of the transistor 116. The emitter 132 of the transistor 116 is also connected to the positive terminal of a power source through a resistor 134, and the collector 136is connected to a negative terminal of the power source.

The emitter 132 of transistor 116 is electrically connected to the base 138 of the transistor 118, and the collector 140 of this transistor is connected to ground. The emitter 142 of the transistor 118 is connected to the same negative terminal of i the power source as the collector 136 of transistor 116 through a resistor 144. The output of the full-wave rectifier V 88F is taken from the emitter 142 of the transistor 118 which isdirectly connected to the emitter 110 of the gate circuit In the particular construction described, the positive terminal of the power source is at a potential of plus 6 volts relative to the collector 140, or ground terminal, and the collector 122 of transistor 114 is electrically connected to a terminal of thepower source having a potential of minus 6 volts. The collector 136 of transistor 116 is connected to a terminal of the power source of minus volts.

Transistors

114 and 116 are a type 2N368, and transistor 118 is ofa type 2N3 12.

The output of the gate 90F charges the capacitor 102F to I theinstantaneous value of the output of the gate 90F at the {moment of a pulse from the toggle and sampling pulse generator 96. In practice, outputs from the'tape' 26 representing 1 always charges the condenser 102F to a potential of known I value, and in the particular construction described, this potential is minus 1.4 volts. For the 0, the condenser will be discharged and in the particular construction described, this potential is approximately minus 0.4 volts or less. This mode of operation is also true for the other gate circuits in the digital to analogue converter 32.

Thesignal from the storage capacitor 96B is fed through the DCamplifier 948 to a precision resistor 146B. In like manner, the charge on the capacitor 1028 is conducted trough the DC amplifier 1008 to a precision resistor 1488. Also, the charge in the

capacitors

96C, 102C, 96E, 102E, 96F, and 102F are conducted through the

DC amplifiers

94C, 100C, 94E, 100E,

941-,and IMF to precision resistors 146C, 148C, 146E, 148E, 146F and 1481 The one terminal of the resistors are all inter- 1 connected and connected to a resistor 150 which is connected tive directions. The output of each of these amplifiers is either a fixed positive value or a fixed negative value with very small deviations.

One of the DC amplifiers, IMF, is also illustrated in FIG. 5b, and the other DC amplifiers are of identical construction. This DC amplifier 11101 utilizes five transistors, 152, 154, 156, 158, and 160. The base 162 of transistor 152 forms the input for the amplifier 1001 and the collector 164 of the transistor 152 is connected to a positive terminal 166 of a power source through a resistor 168. The emitter 170 of transistor 152 is connected to a negative terminal 172 of the power source through a resistor 174, and a second resistor 176 connected to the emitter 170 is connected to ground. The emitter 178 of transistor 154 and the emitter 1811 of transistor 156 are also connected to ground, and the base 182 of transistor 154 is connected to the collector 164 of transistor 152, and is also connected to the base 184 of transistor 156' The collector 186 of transistor 154 is connectedto the positive terminal 188 of the power source through

resistors

190 and 192. The junction of the resistors 190 and 192is connected to the base 194 of transistor 158, and the emitter 196 of transistor 158 is connected to a positive terminal 198 of the power source.

The collector 200 of transistor 156 is connected to a negative terminal 202 of a power source through two resistors 2114 and 206. The junction between the resistors 204 and 2116 is connected to the base 208 of transistor 160. The emitter 211 of transistor 160 is connected to a negative terminal 212 of the power source, and the collector 21.4 of transistor 160 is connected to the collector 216 of transistor 158. The

collectors

214 and 216 form the output of the DC amplifier 1MP.

In the particular construction described, transistor 152, transistor 154, and transistor 160 are type 2N3l2. Transistor 156 is a type 2N369 and transistor 158 is a type 2N3 1 5A. Terminal 188 is at a potential ofplusll) volts, terminal 166 is at a potential of plus 6 volts, terminal 172 is at a potential of minus 6 volts, terminal 202 is at a potential of minus 10 volts. Terminal 198 is at a potential of plus 6 volts and terminal 212 is at a potential of minus 6 volts. with this particular amplifier an input potential of minus 0.78 volts applied to the base 162 of transistor 152 results in an output potential of minus 6 volts, which is the output potentialjappli'ed to terminal 212. When the input potential applied to tl ie'base 162 falls to minus 1.08 volts, the output potential is plus 6 volts'as seen at the

collectors

214 and 216. As a result, a lean always be expected to produce plus 6 volts at the output of the DC amplifier and a 11 will always produce a minus 6 volts at the output of the DC amplifier.

Track 42, 44, 48 and 50 produce allof the digital information needed from the tape 26 which is used for controlling the recorder 24. These four tracks on the tape 26 contain eight bits of information which is enough to control the variable area modulator with an accuracy of one part in 256. To achieve this, the four tracks of the tape 26 carry the information of an S-digit binary number having values between 0 and 255. Ifa mark ofa 1, such as the mark 218 in FIG. 2, occurs simultaneously with a clock count,-that is a mark on the track 46, the mark represents one of the least significant digits, and hence the four least significant digits, of each value encoded on the tape 26 occur on axes which are normal to the axis of elongation of the tape 26 and traverse marks of the track 46 which carry the synchronizing marks. In order of increasing value, the least significant digits occur on tracks 42, 44, 42 and 50, and therefore, the output of the DC amplifier 94F contributes l/256 of the total voltage on the output terminal 62, the output of the amplifier 94E contributes 2/256, the output of the amplifier 94C contributes 4/256, and the output of the amplifier 94B contributes 8/256 of the potential appearing on output terminal 62. In order to achieve this, the resistors of the resistor network 98 are selected to have the same ratios.

The most significant digits of the code impressed upon the tape 26 occur slightly ahead of the clock counts of the track 46, and in FIG. 2, the most significant digit f track 42 is indicated by the mark 220. An electrical pulse generated by the mark 220 is delayed by th delayline 54F to occur simultaneously with an electrical pulse generated by the mark 31% of track 42. Also, the more significant digits of the tracks 44, 48, and 51) are likewise delayed to occur simultaneously with the less significant digits. The most significant digit of the tape occurs in the track and is indicated by the mark 220A in FIG.

2. The tracks 48, 44 and 42 contain decreasingly significant digits preceding the clock count. Hence, the resistor 1488 is l/l28 of the resistor 146F, and the resistor 148C is l/64 of that resistor. In like manner, resistors 1485 and 148F are 1/32 and ll 1 6, respectively, of the value of resistor 146F.

In the particular construction described in this application, resistor 146F has a value of 160,000 ohms, and the output of the terminal 62 when all Is, or marks, confront the playback head assembly 60, a potential of 6 volts is attained. When all 0's confront the playback head 60 on the tape 26, the potential obtained is minus 3.13 volts. For other combinations of digits between these values, the voltage obtained is a function of the digital value of the marks or 1 s on the tape 26.

As indicated in FIG. 4, the output from the resistor network 98 which appears on terminal 62 is impressed upon the input of a direct current power amplifier 222. The output of the direct current power amplifier 222 is impressed upon the recorder 24. In the particular construction described in this application, the recorder 24 is in the form of a variable area light modulator, and this variable area light modulator, designated 224, is illustrated in FIGS. 9 through 11.

As illustrated in FIG. 10, the variable arealight source employs a lamp 226 which is focused on the turntable 20 by means of lens 228, a member 230 defining a slit, and a second lens 229. The light emitted from the lamp 226 is in the form of a narrow elongated beam which falls upon the disc 22 on the turntable 20 along a radius of the disc. The image of the light from the lamp 226 falling upon the turntable 20 is indicated by the dotted line designated 232 in FIG. 9. Lens 228 forms an intermediate image of slit 230 onto a variable area shutter 234,

immediately above the disc 22 which, in turn, is focused on the turntable 20 by means of lens 229. The variable area shutter 234-is in the form of a flat plate with a plurality of indentations 236 at one edge, FIG. illustrating three such indentations. The indentations have straight edges to form teeth, and a shaft 238 extends from the opposite edge of the plate forming the shutter 234. The shaft 238 is mounted coaxially within a cylindrical housing 240, by means of a pair of compliant discs, 242 and 244, mounted on the housing 240. The

discs

242 and 244 have a plurality of coaxial rings 246 which increase the compliance of the

discs

242 and 244 to translation of the shaft 238 along its axis, but the

discs

242 and 244 restrain motion of the shaft 238 to its axis.

The end of the shaft 238 opposite the shutter 234 has a cupshaped electrically insulating member 248 which terminates in a cylindrical portion carrying thereon a coil 250. The coil 250 is electrically connected to the output of the direct current power amplifier 222 illustrated in FIG. 4.

The coil 250 is disposed within an annular gap 252 in a magnetic structure formed by a central pole piece 254, a yoke 256, and a plate 258. The central pole piece 254 is disposed on the axis of the coil 250 and therein, aud tne plate 258 has a central aperture surrounding the coil 250. The plate 258 is connected to the central pole piece 254 by the yoke 256, and the magnetic structure is magnetized to have an oppositemagnetic pole confronting the coil from the central pole piece 254 from that confronting the coil from the plate 258, as illustrated. I

It is to be noted that the beam of light illustrated by the dotted line 232 falling upon the shutter 234 is illustrated as totally disposed upon the shutter and blocked from impinging upon the disc 22 on the turntable 20. This represents the position of the shutter 234 for minimum output from the resistance network 98 as it appears on the terminal 62. As the marks or ls on the tape 26 generate signals in the playback head assembly 60, the output from the resistance network 98 will increase in accordance with the numerical value of the digital number represented by the marks, and a resulting flow of current through the coil 250 will force the shutter to move in a direction inwardly of the housing 240. Asa result, the beam of light represented by the dotted line 232 will begin to pass through the teeth 236 of the shutter 234 and fall upon the photosensitive surface of the disc 22. Since the disc 22 is rotating, tracks of exposed areas on the disc 22 of varying widths will occur. As illustrated, three parallel regions representing a single track will be produced by motion of the shutter 234 relative to the beam of light.

FIG. 12 illustrates an alternate construction for the shutter 2.34 illustrated in FIGS. 9 and 10. In the construction of FIG. 12, the shaft 238 of the variable area modulator is connected to a plate-shaped shutter 234A which has an edge 260 disposed at an angle to the axis of the shaft 238. The edge 260 is illustrated as partially covering the image of the beam of light as illustrated by the dashed line 232, and it is to be noted that a portion of the beam of light extends beyond the edge 260 to impinge upon the disc 22 on the turntable 20. The shaft 238 is translatable in the direction of the arrow of FIG. 12, in exactly the same manner as described in connection with FIG. 9, thereby varying the area of the light beam 232 which is permitted to impinge upon the disc 22 on the turntable 20.

As previously stated, the motor 34 for the transport mechanism must be synchronized to-the turntable 20 in order synchronous motor and has one coil 268 connected to the alternating currentsource 260 and a second coil 270 or control coil connected to the output of the error signal generator.

A comparison signal for the error signal generator is generated by means of a disc 272 affixed about the periphery of the turntable 20 and carrying a coaxial track with the turntable 20 of alternate opaque and transparent sectors of equal length. A lamp 274 is disposed on one side of the track of alternate opaque and transparent sectors of the disc 272, and a photocell 276 confronts the opposite side of the track. A slit member 278 is disposed between the lamp 274 and the disc 272, so that the photocell generates an electrical signal for each transparent sector of the disc 272. This construction has been substantially described in the present inventors U.S. Pat. No. 2,924,138. The photocell 276 is connected to the error signal generator 266, and phase differences between the signals generated from the track 46 of the tape 26 and the position of the disc 272. affixed on the turntable 20 are used to control acceleration and deceleration of the turntable 20 to maintain it in synchronism with the tape 26.

FIG. 6 illustrates the error signal generator 264 in block diagram. The photocell 276 is illustrated connected to the input of an amplifier 280, and the output of the amplifier 280 is connected to a cathode follower 282. The output of the cathode follower 282 is connected to a negative clamp cathode follower 284, and the output of this cathode follower 284 is connected to a toggle circuit 286.

The purpose of the amplifier 280 and

cathode followers

282 and 284 is to amplify and shape the output of the photocell which has essentially sine waveform. The toggle 286 converts this sine wave into a square wave, and the output of the toggle circuit 286 is impressed upon a pulse generator, or multivibrator 288.

The output of this pulse generator 288-is connected to one of two input terminals of a flip-flop 290 through a switch 292. The flip-flop 290 also has another control input terminal, and a switch 294 selects this terminal is also utilized. The output of the resonator 94 which is connected to the reproducing head 30D, FIG. 4, is electrically connected through a phase sifter 296 and a toggle circuit 298 to the pole terminal of the switch 294. As stated above, the photocell 276 generates an essentially sinusoidal wave from the movement of the disc 272 af- 1 1 wave is impressed upon the toggle circuit 286. Essentially square wave pulses are produced by-the toggle circuit, and

. these are employed by the pulse generator 288 to produce positive short pulses of fixed amplitude.

The essentially sinusoidal waves generated by the resonator 94 are also impressed upon the toggle 298 to produce square waves.

The electrical circuit diagram of the flip-flop 290 is illus- I tratedin FIG; 7, and the flip flop 290 is of conventional circuit design. It is to be noted that the output of the toggle 298 is connected through the switch 294 to one grid 300 of the vacuum tube 302 which is utilized in the flip-flop 290, and that a diode 304 is connected in series with this circuit. Also, the output of the pulse generator 288, or multivibrator, is in the form of positive pulses, and these are fed to the grid 310 of a second triode section of the vacuum tube 302. As a result, the flip-flop 290 is triggered by the positive going edge of the pulses from the pulse generator 288 in one. direction, and the positive going edge of the pulse on the toggle 298 flips the flipflop 290 in the opposite direction.

1 FIG. 8 shown synchrograms for the voltages at various points in the circuit illustrating operation 'of the error signal generator. ln curve A of FIG. 8, the rectangular pulses impressed upon the inputof the multivibrator or pulse generator 288 are illustrated, and it is to be noted that the differences in the width of these square wave pulses indicate variations in speed of the turntable 20. Curve B of FIG. 8 illustrates the narrow pulses generated by the multivibrator or pulse generator 288 which are, impressed upon the input of the flip-flop 290.

Curve flip-flop illustrates the output from the toggle 298 which represents the clock pulses generated from the tape 26,

and it is to be noted that these pulses do not vary in length in thesame mannerthat the pulses showed in curve A. Curve D illustrates the output of the fiip flop 290, and it is to be noted t that the leading edge of each pulse of curve D corresponds to the positive edge of a pulse of curve A, while the trailing edge of each pulse of curve D corresponds to a positive going edge of a pulse of curve C. Also, it is to be noted that the width of the pulses vary greatly depending upon the phase relation of the pulses indicated in curves A and C.

, a The output ofthe flip-flop 290, after being amplified by tube 318, is impressed upon the input of a charging circuit 314 which chargesa capacitor 316. As indicated in FIG. 7, the charging circuit 314 has an amplifier employing vacuum tube 320, and is difi'erentiated by a capacitor 322 connected in the H input of an amplifier which includes vacuum tube 324. The output of vacuum tube 324 is taken from a plate, 326, is used to trigger a saw-toothedgenerator which employs vacuum tube 328.'Vacuum tube 328 has a plate 330, grid 332, and

. cathode 334. The plate 330 of vacuum tube 328 is directly connected to the positive terminal 336 of a direct current I source,,the negative terminal of the source being connected to t ground. A grid resistor 338 is connected between the grid 332 and ground. The grid 332 is maintained at a negative potential by'a resistor 340 connected to a negative terminal 342 of the direct currentpower source, and this negative terminal 342 is also connected to the cathode 334 through serially connected

resistors

344 and 346 and a diode 348. A second diode 350 is .waves are of different lengths. The depth of the saw-toothed waves is determined by the width of the negative going pulse of the curve D of FIG. 8. The saw-toothed waves appear on the cathode 334 of vacuum tube 338. Y

A cathode follower 352 having a vacuum tube 354 is con- .nected to the output of the charging circuit. Vacuum tube 354 has a grid 356 which is connected to the cathode 334 of vacuum tube 328. The cathode 358 of vacuum tube 354 is connected to the negative terminal 342 through a resistor 360,

. and a capacitor 362. is connected in parallel with the resistor 360 through a diode 364. The capacitor 362 is also connected through a diode 366 and resistor 368 to the flip-flop output D.

The saw-toothed generator utilizes the capacitor 316 and the resistors 3 44 and 346 to produce saw-toothed waves. The sawtooth waves then pass through the cathode follower 352 and are impressed upon the storage capacitor 362. The storage capacitor 362 is charged through resistor 368 and diode .366 from the plate of vacuum tube 318 as a result of the square wave pulses appearing at this point in the circuit but only to the voltage at the bottom of the sawtooth wave. The diode 366 prevents the capacitor 362 from discharging after the charging pulse terminates. The capacitor 362 discharges through the diode 364 and the resistor 360, but only to the value of the voltage at the bottom of the sawtooth waves. FIG. 8 indicates the manner in which the charge on the capacitor 362 varies.

The charge on the capacitor 362 is the input to the 60 cycle modulator 372 and passes through a damping circuit 370 to the input of the 60 cycle modulator 372. The 60 cycles modu lator produces two outputs indicated in FlG. 8 by the curves G and H, and these are impressed on the input of the push-pull amplifier 374. The output of the push-pull amplifier 374 is connected to the control winding 270 of the motor 266.

The 60 cycle modulator 372 compares the signals appearing at the output of the damping circuit 370 with a fixed reference potential indicated by the battery 375 in FIG. 6 but is actually the divider terminal 380 of the same number in FIG. 7. This fixed reference potential is applied to the junction of two

resistors

376 and 378. The

resistors

376 and 378 are a part of a bridge circuit, and

resistors

382 and 384 are also a part of the bridge and form a junction which is connected to the output of the damping circuit 370. A resistor 386 and a diode 388 connect the'resistors 382 and 376, and a resistor 390 and a diode 392 connect the

resistors

378 and 384. Also, a resistor 394i and a diode 396 are connected in series between the resistor 384 and the resistor 376, and a resistor 398 and a diode 400 are connected in series betweenthe resistors 382 and the resistor 378. An alternating current potential source 402 is connected in parallel with the

resistors

382 and 384. Also, the junction between the

resistors

382 and 384 is connected to the junction 380 between the

resistors

376 and 378 by a diode 404 and a resistor 406, and the junction between this diode and resistor is connected to ground through a resistor 408.

The modulator 372 is a balance bridge circuit, whereby the voltage at the junction between the

resistors

382 and 384 is made the same as at the junction 380. The resistor 390 and diode 392 are effective to connect positive pulses appearing from the AC source 402 between the resistor 390 and the resistor 384 to one of the inputs of the push-pull amplifier 374, and the resistor 394 and diode 396 are effective to conduct negative charges appearing at that point to the other input of the amplifier 374. In like manner, the diode 388 and resistor 386 are effective to conduct positive charges which appear between the resistor 386 and the resistor 382 to the other input of the push-pull amplifier 374, while the resistor 398 and diode 400 conduct negative charges from this point to the first input of the push-pull amplifier 374. In this manner, the unbalanced voltages from the bridge circuit are conducted to the inputs of the push-pull amplifier 374 at the rate of the alternating current source 402, which is 60 cycles in the illustrated construction.

There will be no input to the push-pull amplifier 374 if the output of the damping circuit 370 equals the reference potential of the junction 380. FIG. 8G and FIG. 8H illustrate the two inputs to the push-pull amplifier 374. It is to be noted that the 60 cycle modulator impresses on the input of the push-pull amplifier 374 pulses at a rate of 60 cycles per second which have amplitudes corresponding to the phase difference between the turntable 20 and the tape transport mechanism 28, as shown by the curve F of FIG. 8.

It should also be recognized that the output of the tape 26 may be recorded on the disc 22 by conducting the output of an individual playback head 30 directly to the recorder in order to produce transparent and opaque sectors on the disc 22. In this case, the analogue to digital converter 32 would not be required, and only the output from the playbackhead, for example 39F, would be conducted to the recorder 24 to produce sectors from a given track of the tape 26, such as the track 42 in this illustration.

It should also be recognized that the tape 26 may be replaced by a photographic film. The marks indicating ls, designated in FIG. 3 by the

reference numeral

72, 218, 220 and 72A, are replaced by transparent sectors, and a light source and photocells replace the reproducing heads 30 of the digital signal generating means 36. In this manner, outputs may also be generated which are suitable for controlling the digital to analogue converter 32. I

Those skilled in the art will device manyfurther embodiments of the present invention, and will also devise many modifications of the structure hereinbefore set forth and the methods described. It is therefore intended that the scope of the present invention be not limited by the-foregoing disclosure, but rather only by the appended claims.

lclaim:

l. The method of encoding a member with a plurality of values of a mathematical function comprising the steps of producing an elongated record tape by mathematically deriving in digital form and recording on said tape the digital values of the dependent variable of said function for a plurality of values of the independent variable of said function which differ by equal increments, each recorded digital value of the dependent variable being spaced along the longitudinal axis of the tape by an equal increment from the recorded value of the dependent variable for the next lower independent variable, and each bit of each recorded value of the dependent variable being disposed in a track on the tape parallel to the longitudinal axis of the tape containing bits of other recorded values of the dependent variable of equal significance, translating the tape along its longitudinal axis, generating an electrical signal for each track of the tape, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member with the analogue signal.

2. The method of encoding'a photosensitive disc with a plurality of values of a mathematical function comprising the steps of preparing an elongated record tape by mathematically deriving in binary digital form and recording on said tape the digital values of the dependent variahleof said function for a plurality of values of the dependent variable of said function which differ by equal increments, each recorded value of the dependent variable being spaced along the longitudinal axis of the tape by an equal increment from the recorded value of the dependent variable for the next lower independent variable, and each bit of each recorded value of the dependent variable being disposed in a track on the tape parallel to the longitudinal axis of the tape containing bits of other values of the dependent variable of equal significance, translating the tape along its longitudinal axis, generating an electrical signal for each track of the tape, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, rotatingthe photosensitive disc in synchronism with the translation rate of the tape, and varying the intensity of a light source mounted in a fixed position confronting and focused on a spot on the photosensitive disc, and developing the photosensitive disc. I

3. The method of encoding a member with a plurality of values of a mathematical function comprising the step of programming and operating 'a digital electronic computer having a magnetic tape output to produce a magnetic tape with magnetically polarized areas representing the binary digital value of the dependent variable for a plurality of values of the independent variable of said function, each binary digital value of ing on said tape the digital values of the dependentvariable of l4, the dependent variable being in the form of a plurality of areas representing bits of the binary number and each value being spaced along the longitudinal axis of'the tape by an equal increment from the value of the dependent variable for the next lower independent variable, and each bit of each value of the dependent variable being disposed in a track on the tape parallel to the longitudinal axis of the tape containing bits of other values of the dependent variable of equal significance, translating the tape along its longitudinal axis, generating an electrical signal for each track of the tape, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member.

4. The method of encoding a member with a plurality of values of a mathematical function comprising the steps of producing an elongated record tape by mathematically deriving in digital form and recording on said tape the digital values of the dependent variable of said function for a'plurality of values of the independent variable of said function which differ by equal increments, each recorded value of the dependent variable being spaced along the longitudinal axis of the tape by an equal increment from the recorded value of the dependent variable forthe next lower independent variable, and each recorded value of thedependent'variable having a plurality of separately recorded bits, translating the tape along its longitudinal axis, generating an electrical signal for each bit of each recorded value of the tape, converting the electrical signals generated from all the bits of each value in sequence into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member with the analogue signal.

5. The method of encoding a photosensitive disc with a plurality of values of a mathematical function comprising the steps of producing an elongated record tape by mathematically deriving in binary digital form and recording on said tape the digital values of the dependent variable of said function for a plurality of values of the independent variable of said function, said recorded values of dependent variable being arranged in sequence for continuously increasing values of the independent variable, each recorded value ofthe dependent variable being spaced along the longitudinal axis of the tape from the recorded value of the dependent variable for the next lower independent variable, and each bit of each recorded value of the dependent variable being separately recorded on the tape, translating the tape along its longitudinal axis, generating separate electrical signals for each bit of the recorded value in one fixed area through which the tape passes at the same time, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, rotatingthe photosensitive disc in synchronism with the translation rate of the tape, and varying the intensity of light source in a fixed position confronting and focused on a spot on the photosensitive disc responsive to the analogue signal, and developing the photosensitive disc.

6. The method of encoding a member with a plurality of values of a mathematical function comprising the steps of producing an elongated magnetic record tape by mathematically deriving in binary digital form and magnetically recordsaid function for a plurality of values of the independent variable of said function each binary digital value of the dependent variable being in the form of a number of areas representing bits of the binary number and each value being spaced along the longitudinal axis of the tape from the value of the dependent variable for the next lower independent variable, and each bit of each value of the dependent variable being separately recorded oh the tape, translating'the tapealong its longitudinal axis; generatingg'separate electrical signals for each bit of anyvalue of the dependent variable located in a area at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member responsive to the analogue signal.

"H050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,568,182 Dated March 2, 1971 Inventor(g) Edward M. JOHGS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Col. 6 line 69, Change "140" to through-;

Col. 7, line 11, After 88B change "88A" to --78C-;

line 50, Change 1 to -"l";

line 53, Change 0 to --"0"-;

Col. 8, line 42, Change 1 to -"l";

line 43, Change 0 to -"O"-;

line 46 Change "Track" to -Tracks--,-

line 53, Change "of" to or-;

line 53, Change 1 to "l"-;

line 73, Change "318" to 2l8--;

Col. 9, line 10, Change l's to --"l's":

line 12, Change 0' s to -"0's"-;

line 15, Change l's to -"l' s";

line 69, Change 1' s to -"l's"--;

Col. 11, line 22, Change "shown" to shows;

Col. l4,line 70, After "function" insert a comma Signed and sealed this 16th day of November 1971 (SEAL) Lttest:

EDWARD M.FLETGHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents

Claims

1. The method of encoding a member with a plurality of values of a mathematical function comprising the steps of producing an elongated record tape by mathematically deriving in digital form and recording on said tape the digital values of the dependent variable of said function for a plurality of values of the independent variable of said function which differ by equal increments, each recorded digital value of the dependent variable being spaced along the longitudinal axis of the tape by an equal increment from the recorded value of the dependent variable for the next lower independent variable, and each bit of each recorded value of the dependent variable being disposed in a track on the tape parallel to the longitudinal axis of the tape containing bits of other recorded values of the dependent variable of equal significance, translating the tape along its longitudinal axis, generating an electricAl signal for each track of the tape, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member with the analogue signal.

2. The method of encoding a photosensitive disc with a plurality of values of a mathematical function comprising the steps of preparing an elongated record tape by mathematically deriving in binary digital form and recording on said tape the digital values of the dependent variable of said function for a plurality of values of the dependent variable of said function which differ by equal increments, each recorded value of the dependent variable being spaced along the longitudinal axis of the tape by an equal increment from the recorded value of the dependent variable for the next lower independent variable, and each bit of each recorded value of the dependent variable being disposed in a track on the tape parallel to the longitudinal axis of the tape containing bits of other values of the dependent variable of equal significance, translating the tape along its longitudinal axis, generating an electrical signal for each track of the tape, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, rotating the photosensitive disc in synchronism with the translation rate of the tape, and varying the intensity of a light source mounted in a fixed position confronting and focused on a spot on the photosensitive disc, and developing the photosensitive disc.

3. The method of encoding a member with a plurality of values of a mathematical function comprising the step of programming and operating a digital electronic computer having a magnetic tape output to produce a magnetic tape with magnetically polarized areas representing the binary digital value of the dependent variable for a plurality of values of the independent variable of said function, each binary digital value of the dependent variable being in the form of a plurality of areas representing bits of the binary number and each value being spaced along the longitudinal axis of the tape by an equal increment from the value of the dependent variable for the next lower independent variable, and each bit of each value of the dependent variable being disposed in a track on the tape parallel to the longitudinal axis of the tape containing bits of other values of the dependent variable of equal significance, translating the tape along its longitudinal axis, generating an electrical signal for each track of the tape, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member.

4. The method of encoding a member with a plurality of values of a mathematical function comprising the steps of producing an elongated record tape by mathematically deriving in digital form and recording on said tape the digital values of the dependent variable of said function for a plurality of values of the independent variable of said function which differ by equal increments, each recorded value of the dependent variable being spaced along the longitudinal axis of the tape by an equal increment from the recorded value of the dependent variable for the next lower independent variable, and each recorded value of the dependent variable having a plurality of separately recorded bits, translating the tape along its longitudinal axis, generating an electrical signal for each bit of each recorded valuE of the tape, converting the electrical signals generated from all the bits of each value in sequence into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member with the analogue signal.

5. The method of encoding a photosensitive disc with a plurality of values of a mathematical function comprising the steps of producing an elongated record tape by mathematically deriving in binary digital form and recording on said tape the digital values of the dependent variable of said function for a plurality of values of the independent variable of said function, said recorded values of dependent variable being arranged in sequence for continuously increasing values of the independent variable, each recorded value of the dependent variable being spaced along the longitudinal axis of the tape from the recorded value of the dependent variable for the next lower independent variable, and each bit of each recorded value of the dependent variable being separately recorded on the tape, translating the tape along its longitudinal axis, generating separate electrical signals for each bit of the recorded value in one fixed area through which the tape passes at the same time, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed point at a given time, rotating the photosensitive disc in synchronism with the translation rate of the tape, and varying the intensity of light source in a fixed position confronting and focused on a spot on the photosensitive disc responsive to the analogue signal, and developing the photosensitive disc.

6. The method of encoding a member with a plurality of values of a mathematical function comprising the steps of producing an elongated magnetic record tape by mathematically deriving in binary digital form and magnetically recording on said tape the digital values of the dependent variable of said function for a plurality of values of the independent variable of said function each binary digital value of the dependent variable being in the form of a number of areas representing bits of the binary number and each value being spaced along the longitudinal axis of the tape from the value of the dependent variable for the next lower independent variable, and each bit of each value of the dependent variable being separately recorded on the tape, translating the tape along its longitudinal axis, generating separate electrical signals for each bit of any value of the dependent variable located in a fixed area, converting the electrical signals into a single analogue electrical signal which is a function of the numerical value of the dependent variable on the tape passing a fixed area at a given time, moving the member in synchronism with the translation rate of the tape, and modulating a recording means mounted in a fixed position confronting a portion of the member responsive to the analogue signal.