United States Patent [19]
`Goldwasser et al.
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`US005241428A
`5,241,428
`[II] Patent Number:
`[45] Date of Patent: Aug. 31, 1993
`
`[54] VARIABLE-DELAY VIDEO RECORDER
`[76]
`Inventors: Eric P. Goldwasser, 993 Barberry Rd,
`Yorktown Heights, N.Y. 10598;
`Romi E. Goldwasser, 140 E. 46th St.,
`Apt. 6-B, New York, N.Y. 10017
`[21] Appl. No.: 669,061
`[22] Filed:
`Mar. 12, 1991
`[51]
`Int. CI.s ....................... GUB 20/00; GliB 20/10
`[52] u.s. Cl ........................................... 360/7; 360/32;
`360/39
`[58] Field of Search ................ 360!7, 32, 54, 13, 14.1,
`360/14.2, 14.3, 39; 369/258, 259; 358/310
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`3,341,833 9/1967 Jones ................................... 369/259
`3,645,539 2/1972 Jenkins .................................... 360/7
`3,682,363 8/1972 Hull .................................. 360/13 X
`4,283, 735 8/1981 Jagger ..................................... 358/4
`4,319,286 3/1982 Hanpachern .......................... 360/33
`4,408.309 10/1983 Kiesling et al. .................... 360/7 X
`4,430,676 2/1984 Johnson ................................ 360/13
`4,445,195 4/1984 Yamamoto ........................ 360/13 X
`4,633,331 12/1986 McGrady eta!. ................ 360/32 X
`4,876,670 10/1989 Nakabayashi et al. ............. 365/194
`4,891,715 1/1990 Levy .............................. 360/33.1 X
`4,963,866 10/1990 Duncan ............................. 360/32 X
`4,991,033 2/1991 Takeshita .............................. 360/32
`5,021,893 6/1991 Scheffler ........................... 360/32 X
`5,063,453 11/1991 Yoshimura et al. .................. 360/32
`
`Primary Examiner-David Mis
`Attorney, Agent, or Firm-Michael M. deAngeli
`[57]
`ABSTRACf
`A video recorder and playback device allowing simul(cid:173)
`taneous recording and playback of program material,
`including means for controllably varying a time delay
`between the recording and playback of recorded mate(cid:173)
`rial. This allows, for example, playback of previously
`recorded material to be temporarily stopped and then
`resumed without interrupting the recording of new
`material. A user can arrange to start recording a broad(cid:173)
`cast program (while the user is not at home, for exam(cid:173)
`ple) in the conventional way via stored instructions, and
`then begin watching the recording several minutes or
`hours later, before the program is over, without stop(cid:173)
`ping the recording. The user can also interrupt the
`playback of a program that is being recorded as it is
`being watched (to take a telephone call, for example),
`and then resume playback of the· program (after the
`phone call is over) without stopping the recording. The
`user can then watch the rest of the program delayed by
`a time period equal to the length of time of the interrup·
`tion. If there are portions of the program that the user
`does not want to see (e.g. commercials), he can speed
`(i.e., fast forward) through those recorded portions and
`catch up to the live broadcast. The user can also rewind
`and replay portions of the program ·as the video re(cid:173)
`corder continues to record the program.
`
`14 Claims, 4 Drawing Sheets
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`Dish, Exh. 1005, p. 1
`
`

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`U.S. Patent
`
`Aug. 31, 1993
`
`Sheet 1 of 4
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`5,241,428
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`

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`U.S. Patent
`
`Aug. 31, 1993
`
`Sheet 2 of 4
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`5,241,428
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`U.S. Patent
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`Aug. 31, 1993
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`

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`1
`
`5,241,428
`
`VARIABLE-DELAY VIDEO RECORDER
`
`FIELD OF THE INVENTION
`The present invention relates to an apparatus which
`permits the simultaneous recording and playback of
`video material with a variable delay between the re(cid:173)
`cording of a given segment of a video program and the
`subsequent playback of that segment.
`
`2
`SUMMARY OF THE INVENTION
`These objects are achieved, according to the present
`invention, by recording video on a recording medium
`while simultaneously playing back previously recorded
`video from the medium, while allowing control of a
`variable time delay between recording and playback.
`The video recorder of the invention is described in
`three embodiments. In the first "sequential" and second
`10 "random access" embodiments, the functional attributes
`of the device are identical. In the third "multiple tape"
`embodiment, the functional attributes are somewhat
`different.
`In the first "sequential" embodiment, the video pro(cid:173)
`gram material is recorded on a sequential medium, typi(cid:173)
`cally videotape. In a second "random access" embodi(cid:173)
`ment, the video signal is converted to digital form and
`recorded in a random access memory, which can be any
`of several known types. For example, this random ac-
`cess memory could employ magnetic or optical media
`or a solid state memory.
`More particularly, the term "random access mem-
`ory" is commonly used to refer to a particular type of
`solid state memory. The term as used herein includes
`such solid state devices, but as a consequence of the
`particular nature of the invention, such devices as mag-
`netic or optical discs, which permit rapid access to
`essentially any portion of the stored records, are also
`included. Not included within the term "random access
`memory" as used herein is tape storage media, which is
`sequential in character. That is, use of tape media re-
`quires that a quantity of tape be physically moved in
`order to access a particular record (except when se(cid:173)
`quentially stored records are accessed). This is not true
`of "random access" memory devices as used herein.
`In the first "sequential" embodiment of the invention,
`the video signal is recorded continuously on tape as in
`the prior art. The signal can be recorded in analog form
`as conventional, or could be converted to digital form
`and stored as a sequence of digital samples. In either
`case, in this embodiment of the invention, the signal is
`stored in its original sequence on tape. However, in(cid:173)
`stead of providing a fixed physical spacing between
`recording and playback heads as in the prior art, the
`device of the invention comprises an accumulator for
`physically storing a variable quantity of tape between
`the recording and playback heads, and comprises sepa(cid:173)
`rate tape transport mechanisms for driving the tape past
`the recording and playback heads so that these can be
`independently controlled.
`For example, suppose one has programmed a ma(cid:173)
`chine according to the invention to commence record(cid:173)
`ing at a particular time, say 10:00 p.m. One then arrives
`home at, say, 10:30 p.m. In the interim, the tape re(cid:173)
`corded by the record head has been physically stored in
`the accumulator located between the record head and
`the playback head. Therefore, if one then wants to com(cid:173)
`mence watching the stored program, one can activate
`the playback drive, driving the tape from the accumula(cid:173)
`tor past the playback head, while the tape continues to
`be fed into the accumulator, completing the recording
`of the program. One can readily "fast forward" through
`unwanted program material such as commercials, while
`recording the entire program without interruption.
`Similarly, if one is watching a program and receives
`an interruption such as a telephone call or the like, one
`can cause the program to be recorded while storing the
`tape in the accumulator. One can subsequently return to
`
`25
`
`BACKGROUND OF THE INVENTION
`In the broadcast industry, audio and video recording
`and playback machines have been used to delay live
`broadcasts by several seconds to permit deletion of 15
`inappropriate language or gestures. These machines
`provide a fixed delay between the recording and play(cid:173)
`back of a given section of audio and/or video.
`Many commercially available video cassette recorder
`(VCR) machines, i.e., videotape recorders with multi· 20
`pie heads, permit the user to play back recorded mate(cid:173)
`rial immediately after it has been recorded, by position(cid:173)
`ing the play-back head after the record head. This ena(cid:173)
`bles the user to monitor the quality of the recording and
`watch the broadcast essentially live.
`These machines do not allow the user to vary the
`delay between the recording and playback of segments
`of video.
`More particularly, such conventional machines do 30
`not allow one to view material as it is being recorded,
`other than simultaneously or immediately after it has
`been recorded, as above. This imposes many inconve(cid:173)
`niences. For example, often one will anticipate arriving
`home at a particular hour, sometime after the com- 35
`mencement of a particular broadcast program one de(cid:173)
`sires to watch. One must therefore set one's VCR to
`commence recording at the beginning of the program.
`If one then arrives a few minutes after the beginning of
`the program, one can watch the end of the program in 40
`real time, but cannot see its beginning until after the
`entire program has been recorded.
`Similarly, often one will be watching a particular
`program when one must temporarily cease watching it,
`for example, to take a telephone call or the like. It 45
`would obviously be convenient to be able to record the
`program from that point forward, complete the tele(cid:173)
`phone call, and simply watch the remainder delayed by
`the length of time of the interruption. However, no
`devices are now available which permit this facility. It 50
`also is not possible to employ two separate video cas(cid:173)
`sette recorders to overcome these inconveniences.
`
`OBJECTS OF THE INVENTION
`A principal object of the present invention is to pro- 55
`vide an improved video recorder and playback device
`that can be used to record and playback video material
`independently, for example, so as to allow the viewer to
`pause the playback for a variable period of time without 60
`interrupting the recording.
`A further object of the present invention is to provide
`an apparatus that can be used to record and playback
`video material while allowing the user to effectively
`reposition the stored material with respect to the play- 65
`back device to allow "fast forward" or "rewind" of the
`material being played back, without interruption of the
`recording.
`
`Dish, Exh. 1005, p. 6
`
`

`
`5,241,428
`
`20
`
`3
`the program and watch the portion of the program
`which has been stored in the interim. If the interruption
`is comparable in length to the combined length of all
`unwanted program material, ultimately one may catch
`up to the program before its end.
`In the random access embodiment, the video signal is
`stored on random access media such as a magnetic or
`optical disk or in solid state memory. A control device
`maintains the addresses of the segment(s) of the re(cid:173)
`corded material in the memory device, so that they can 10
`be reassembled in the proper sequence for playback.
`Typically the video signal will be converted to digital
`form prior to storage.
`In both "sequential" and "random access" embodi(cid:173)
`ments of the invention the video program material is 15
`effectively stored in a so-called FIFO (first in-first out)
`buffer of variable length so that the user can view the
`video material in the sequence in which it is broadcast,
`while varying the delay between recording and play-
`back of given material.
`In the third "multiple tape" embodiment of the inven(cid:173)
`tion, three essentially conventional video tape cassettes
`(or other tape supply devices) and three separately
`controllable tape transport mechanisms, with three cor(cid:173)
`responding record and playback heads, are employed. 25
`A microprocessor controls the individual motion of the
`three tapes past their respective recording and playback
`heads, responsive to user controls. In this embodiment
`of the invention, the user can still view a program while
`a subsequent portion of the program is being recorded. 30
`However, the user may experience delays during cer(cid:173)
`tain operations of the device. In essence, one of the
`tapes records while a second can be playing back previ(cid:173)
`ously recorded material. The microprocessor maintains
`a list of the sequence in which the various segments of 35
`the program are recorded and can readily play them
`back in their proper sequence responsive to user instruc(cid:173)
`tions.
`
`4
`information on a medium other than tape per se, and a
`third "multiple-tape" embodiment of the invention. In
`each, the manner of storage of the video signal on the
`medium is not itself particularly significant. For exam(cid:173)
`ple, in the first embodiment of the invention, the video
`signal could be digitized prior to storage rather than
`stored in analog form as broadcast, and as stored in
`video recorders as currently used. Due to the sequential
`nature of tape, comparable facilities for physical han(cid:173)
`dling of the tape are needed to provide variable delay
`between recording and playback according to the in-
`vention, regardless of the actual method of recording
`employed.
`FIG. 1 shows an embodiment of the invention in
`which tape stored in a conventional video cassette is
`employed according to the invention to allow variable
`delay between recording and playback. A supply of
`video tape 1 is provided wound on the supply spindle 2
`of a conventional videotape cassette 3. The tape is
`threaded past rollers 4 and 5 and the combination of
`record head 6 and a generally conventional drive mech-
`anism, shown schematically as a capstan 6a. Capstan 6a
`is controlled by a control circuit 32 which also controls
`a comparable capstan 18a (or equivalent conventional
`drive element) driving the tape past the playback head
`18. The motion of the tape 1 past the record head 6 and
`the playback head 18 is thus independently controllable,
`in contrast to conventional video tape recorders,
`wherein the tape is driven past the two heads by a single
`drive mechanism, so that a variable delay between re(cid:173)
`cord and playback can not be provided.
`The tape leaving the combination of the record head
`6 and the capstan 6a passes by roller 7 and is driven by
`a pair of rollers 8, 9 onto an accumulator tray 10. Pairs
`of rollers 11, 12 and 13, 14, the operation of which is
`detailed below, control the disposition of the tape on the
`tray. Tape is pulled from the tray by rollers 15, 16 be(cid:173)
`fore passing by roller 17, the combination of playback
`head 18 and capstan 18a, and rollers 19 and 20 and is
`BRIEF DESCRIPTION OF THE DRAWINGS
`40 finally wound upon the takeup spindle 21 of the tape
`The invention will be better understood if reference is
`cassette 3. At least roller pairs 8, 9; 11, 12; 13, 14; and 15,
`16, in addition to spindles 2 and 21 and capstans 6a and
`made to the accompanying drawings, in which:
`18a, are powered for positive tape motion control, re-
`FIG. 1 is a schematic diagram of a video recorder in
`sponsive to control signals from controller 32.
`the first "sequential" embodiment of the invention;
`FIG. 2(a), 2(b) and 2(c) show schematically the steps 45 When the unit is in record mode, the rollers of pairs
`in operation of a particular accumulator for tape which
`8, 9, and 11, 12 are caused to rotate in opposite direc-
`may be useful in implementation of the "sequential"
`tions to pull the tape off the rotating supply spindle 2
`embodiment of the invention of FIG. 1;
`past the combination of record head 6 and capstan 6a,
`FIG. 3 is a schematic diagram of a "random access"
`and push the tape into the accumulator portion 27 of the
`embodiment of the invention;
`50 tray 10, that is between roller pairs 11, 12 and 13, 14.
`FIG. 4 is a flow chart for a computer algorithm When the unit is in playback mode, the rollers of pairs
`13, 14 and 15, 16 are rotated in opposite directions to
`which can be used to implement the features of the
`invention in the "random access" embodiment of FIG.
`pull the tape from the tray 10 and past the combination
`of playback head 18 and capstan 18a, after which it is
`3;
`FIG. 5 shows a block diagram of the "multiple tape" 55 wound upon the rotating takeup spindle 21.
`If the playback operation is paused during a record-
`embodiment of the invention; and
`FIG. 6 shows a diagram illustrating the operation of
`ing operation, takeup spindle 21, capstan 18a and roller
`the "multiple tape" embodiment of the invention over
`pairs 13, 14 and 15, 16 stop rotating, responsive to con-
`time.
`trol signals from controller 32, while the supply spindle
`60 2, capstan 6a, and roller pairs 8, 9, and 11, 12 continue
`rotating, so that the tape begins to accumulate in the
`tray 10 between roller pairs 11, 12, and 13, 14. In order
`to ensure uniform storage of the tape on the accumula(cid:173)
`tor tray, rollers 11 and 12 are moved back and forth
`65 across the tray 10 in a direction perpendicular to the line
`between the pairs of rollers 8, 9 and 15, 16. This is ac(cid:173)
`complished by a reciprocation mechanism shown, for
`example, as including rotating eccentric 22. One end of
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`As described above, this invention includes three
`preferred embodiments: a first "sequential" embodi(cid:173)
`ment in which the video program material is recorded
`on conventional videotape or the like, in its original
`sequence, a second "random access" embodiment in
`which the information is stored as addressable blocks of
`
`Dish, Exh. 1005, p. 7
`
`

`
`5,241,428
`
`5
`a rod 24 is affixed to the eccentric at a pivot point 23.
`The opposite end of rod 24 drives the assembly of rol(cid:173)
`lers 11 and 12 transversely across the tray, as indicated
`by arrows lla, 12a. The rollers 11 and 12 and the recip(cid:173)
`rocating drive rod assembly move linearly along the
`tray as the tray fills over time, as indicated by arrow 33.
`This causes the accumulated tape to be deposited in the
`accumulator portion 27 of the tray 10 in a uniform zig(cid:173)
`zag pattern, as shown. In some cases, additional devices
`to control the disposition of the tape on the tray may be 10
`desirable; for example a wall preventing the stacked end
`portions of the loops of tape from extending behind the
`rollers 11 and 12 may be desirable.
`When the playback mode is restarted, capstan 18a,
`roller pairs 13, 14 and 15, 16 and spindle 21 are set 15
`rotating again, responsive to control signals from con(cid:173)
`troller 32, to pull the tape accumulated at 27 past the
`playback head 18 and onto the takeup spindle 21. In this
`case the amount of tape in the tray 10 will remain con(cid:173)
`stant as one section of tape moves out of the tray and 20
`past the playback head 18 while another section of tape
`moves past the recording head 6 and into the tray 10.
`If the unit is put into fast forward mode, capstan 18a,
`and roller pairs 13, 14 and 15, 16 pull tape out of the
`accumulator portion 27 of the tray faster than the rollers 25
`8, 9 and 11, 12 deposit new tape in the tray, so that the
`amount of tape in the tray decreases.
`It will be apparent that independent control of the
`speed of the capstans 6a and 18a, as well as the associ(cid:173)
`ated rollers, under control of the control circuitry 32, is 30
`important so that according to the invention a variable
`delay between recording and playback can be provided.
`This allows playback to be paused or reversed, or the
`speed of the tape past the playback head to be increased
`(in the "speed search" or "fast forward" or "rewind" 35
`modes) without affecting the speed of the tape past the
`recording head.
`In order to preserve the normal rewind function, for
`example, to allow one to see the same scene repeatedly,
`without impeding the record function, it is important 40
`that the recorder also permit tape in the FIG. 1 embodi(cid:173)
`ment to be returned to the tray 10 from the takeup
`spindle 21. Tape on the takeup spindle 21 can be re(cid:173)
`turned to the tray 10 by reversing the direction of the
`capstan 18a and roller pairs 13, 14 and 15, 16. Eccentric 45
`28 and rod 29 are provided to drive rollers 13 and 14
`back and forth. This ensures the tape is stacked in the
`regular zig-zag pattern. Moreover, this stacking can be
`accomplished while tape is entering the accumulator
`portion of the tray 10 from the recording side via rollers 50
`8, 9 and 11, 12. Hence any section of the recorded por(cid:173)
`tion of the tape can be brought to the playback head 18,
`and the conventional pause, speed search, reverse
`search, fast forward, and rewind functions can all be
`accomplished with respect to the portion of the tape 55
`that has already been recorded on, without disturbing
`recording of new material on the portion of the tape
`withdrawn from the supply spindle 2.
`FIGS. 2(a)-2(c) show an alternative embodiment lOa
`of the accumulator of FIG. 1. In this embodiment, the 60
`rollers 8 and 9 drive the tape 1 between sets of opposed
`idler rollers 34 and 35. The sets of idler rollers are
`mounted on frames 36 and 37 which are movable with
`respect to one another as shown by arrows 39 and 40.
`Relative movement of the sets of rollers allows more or 65
`less tape to be stored in the accumulator lOa, depending
`on the direction of the relative movement. For example,
`when the record and playback capstans 6a and 18a are
`
`6
`operating at the same speed, that is so that no net tape is
`to be stored in or withdrawn from the accumulator, the
`sets of idler rollers 34 and 35 are stationary. If it is de(cid:173)
`sired to store tape in the accumulator lOa, for example,
`so as to enable the viewer to take a telephone call during
`the recording of a program, the first set of rollers 35
`begins gradually to move in one direction away from
`the line connecting the input rollers 8 and 9 and the
`output rollers 15 and 16, while the other set of rollers 34
`moves in the opposite direction. As shown in FIGS.
`2(b) and (c), as these sets of rollers 34 and 35 move
`further apart, a gradually increasing amount of tape 1 is
`stored in the accumulator lOa. When it is desired to
`withdraw tape from the accumulator lOa faster than it is
`being fed into the accumulator, for example during fast
`forward playback of a program being recorded, the sets
`of rollers 34 and 35 are gradually brought closer to one
`another. The accumulator lOa is simply controlled by
`controlling the movement of the frames 36 and 37 in
`accordance with the control signals provided to the
`capstan 6a and 18a by the controller 32.
`FIG. 3 shows schematically a "random access" em(cid:173)
`bodiment of the invention, in which the video signal is
`stored on a non-sequential medium in digital format.
`In this embodiment, the recording device (FIG. 3)
`includes a signal sampling circuit 51 and an analog-to(cid:173)
`digital converter 52 which together create digital sam(cid:173)
`ples of the video signal being recorded, ·which are
`stored in a random access memory 53. Playback is ac(cid:173)
`complished by retrieving these stored samples from
`memory 53 and converting them back via a digital-to(cid:173)
`analog converter 54 to an analog video signal. The
`reconstituted analog video signal is supplied to a video
`signal generator 55 which outputs a conventional video
`signal which can be displayed on a standard TV display
`56. Recording and playback may be done essentially
`simultaneously by multiplexing writing to and reading
`from the memory 53. In this embodiment playback can
`clearly take place from any portion of the memory and
`at any speed without affecting the recording. Control of
`such a random access memory to implement the various
`desired functions mentioned above is well within the
`skill of the art.
`The locations at which the digitized video samples
`are stored in the random access memory 53 are con(cid:173)
`trolled by an address controller 58, which in turn is
`responsive to commands received from a user control
`panel 50. Operation of the address controller 58 is gen(cid:173)
`erally described in connection with FIG. 4.
`To conserve the amount of storage space required to
`store a given quantity of the digitized video signal, the
`digitized signal can be compressed in a data compressor
`57, removing redundant information prior to storage,
`and decompressed in a decompressor 59 prior to recon(cid:173)
`stitution by the digital-to-analog converter 54. Such
`data compressors and decompressors are known per se
`and the details of their operation are not critical to the
`present invention.
`FIG. 4 shows a flow chart for an algorithm which
`can be used to control storage and retrieval of such
`digitized video samples from the memory 53 (FIG. 3).
`The algorithm is entered at block 100, at which a byte
`of the digitized video signal is received from the analog
`to digital converter 52. At step 102, this byte is stored in
`the memory 53 at an address designated by a write
`pointer. The write pointer is then incremented by one at
`block 104. The subsequent byte will thus be stored at
`the next address in memory 53. This process allows data
`
`Dish, Exh. 1005, p. 8
`
`

`
`5,241,428
`
`25
`
`7
`representing the video signal to be continuously stored.
`During simultaneous playback, in block 106 a byte
`stored at a location pointed to by a read pointer is
`fetched from the memory 53 and sent at block 108 to the
`digital-to-analog converter 54, which as noted above
`converts it back to an analog signal which is sent to the
`display 56. At block 110 the interrupt mask of the com(cid:173)
`puter is checked briefly to allow an interrupt from the
`user control panel 50. At block 112 any interrupt from
`the control panel is detected; such an interrupt might 10
`indicate, for example, that the orderly playback process
`implemented by blocks 106 and 108 is to be varied. If so,
`at block 114 the read pointer is changed to implement
`the command received via the interrupt. Block 100 is
`then reentered. If no interrupt is detected, the read 15
`pointer is incremented at block 116 and block 100 is
`reentered, so that both recording and playback con(cid:173)
`tinue.
`As discussed above, the "sequential" embodiment of
`FIGS. 1 and 2(a)-2(c) relate to physical storage of tape 20
`media in a manner which permits a variable amount of
`tape to be stored between the recording and playback
`heads, so as to provide a variable delay between record(cid:173)
`ing and playback times. As discussed in connection with
`FIGS. 3 and 4, it is also possible to store the video signal
`as a series of digital samples and to read the data out of
`the memory as needed for playback purposes. This
`eliminates the mechanical necessity of storing varying
`amounts of tape addressed in connection with FIGS. 1 30
`and 2(a)-(c). Thus in the "random-access" embodiment
`of the invention, the digitized video signal is stored in
`individually addressable portions, which are accessed in
`the sequence in which they were stored, to reconstitute
`the original video signal.
`The flowchart of FIG. 4 contemplates that each byte
`of the digital data representative of the video signal will
`be stored separately and accessed individually. It will be
`recognized by those of skill in the art that digitizing a
`typical video signal results in generation of a large num- 40
`ber of data bytes per second, yet that the user does not
`require access to each data byte separately; in most
`circumstances, allowing the user to access the signal at
`one second intervals will be more than adequate. There(cid:173)
`fore, the processing steps could be simplified in a man- 45
`ner well understood by those of skill in the art, by stor(cid:173)
`ing the digitized data in blocks of length equivalent to
`one second and allowing the user simply to access these
`in sequence, through the interrupt routine as described
`above or the like. Maintaining control of the sequence 50
`of blocks of data representing the stored signal is simply
`a matter of maintaining a list in sequence of the ad(cid:173)
`dresses at which the blocks were stored in the memory.
`The system's response to user commands would be
`much faster than experienced with conventional video 55
`recorders. "Fast forwarding", for example, would be
`accomplished simply by jumping ahead in the list of
`addresses.
`The selection of the memory type similarly is within
`the skill of the art, and a particular implementation 60
`might involve two memory types. For example, it might
`be desirable to buffer a small amount of data, e.g., one
`second's worth, in a solid state FIFO buffer until data
`compression has been performed, and then store it on a
`conventional "hard disk" as employed in personal com- 65
`puters. Use of a buffer memory would similarly simplify
`multiplexing of recording and playback operations to
`the disk.
`
`8
`As mentioned above, FIGS. 5 and 6 relate to a further
`"multiple tape" embodiment of the invention in which
`at least three individual video tapes are separately pro(cid:173)
`vided, each with its own separately controllable trans(cid:173)
`port mechanism and record and playback heads. In this
`embodiment, the device according to the invention
`comprises three individual, essentially conventional,
`videotape recording mechanisms denominated 80, 81,
`and 82 in FIG. S. These are individually controlled by a
`microprocessor or equivalent controller device 83,
`which is in tum responsive to user controls input at a
`key pad, remote control device or the like, indicated at
`84. These three units 80, 81 and 82 can be considered to
`be a conventional VCR, or other videotape recorder,
`each being separately controllable for the usual tape
`transport functions and for recording and playback of
`the video signal from the tape. The outputs of the three
`recorders 81, 82 and 83 are fed together to a single
`display device 85.
`In essence, the three essentially conventional record(cid:173)
`ing mechanisms are used in this embodiment of the
`invention, so that the novel functions described above
`can be provided using present day tape transport and
`recording technology. As noted, functionally these
`three mechanisms are identical to three conventional
`tape recorders as presently available, with the exception
`that they are controlled by the microprocessqr rather
`than directly by the user. It would be impracticably
`complicated for a user to operate three separately con(cid:173)
`trollable conventional recorders to obtain the functions
`provided according to the invention.
`FIG. 6 is a diagram showing the sequence of opera(cid:173)
`tion of the three recorders 80, 81 and 82, denominated
`machines 1, 2, and 3, to illustrate the manner in which
`35 they are operated to provide the functions of the inven(cid:173)
`tion. In FIG. 6, time is shown extending from left to
`right, and the left and right facing arrow points denote
`the direction of motion of the tape carried by the corre-
`sponding recorder at any particular time t1, t2, ... tn.
`The letters beneath the arrow points indicate the seg(cid:173)
`ment of the program of interest passing the record/-
`playback head of the corresponding machine at any
`given time, such that the entire program consists of
`segments A, B, C, D, ... in sequence. The letters which
`are underlined denote the segment being displayed at
`any given time. Finally, the letters in parentheses be-
`neath the segment indicators indicate the operation
`which is being performed by the