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Claims  |
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I claim:
1. Recording and reproducing apparatus comprising:
a record medium capable of receiving and recording information in a
plurality of separated tracks,
means for recording and reproducing digital information in said tracks,
input circuit means for receiving a substantially continuous flow of said
digital information, and for separating the same into compressed segments
corresponding to said tracks for recording the same, said input circuit
means comprising a first in first out memory for receiving a continuous
flow of digital information, an up-down counter for registering full and
empty conditions of said memory, a clock signal generator, and circuit
means responsive to said full and empty conditions for controlling the
clock generator signal to withdraw information from said memory for
recording said information when said memory is full and emptying the
memory during the period of a desired information track,
and output circuit means for reading out the digital information from said
tracks and for expanding the same into a substantially continuous stream.
2. The apparatus according to claim 1, wherein said circuit means includes
a second counter for counting a number of digital clock bits corresponding
to a predetermined track length, and comparison means for comparing an
output of said up-down counter with an output of said second counter to
control the rate of said clock generator.
3. Recording and reproducing apparatus comprising:
a record medium capable of receiving and recording information in a
plurality of separated tracks,
means for recording and reproducing digital information in said tracks,
input circuit means for receiving a substantially continuous flow of said
digital information, and for separating the same into compressed segments
corresponding to said tracks for recording the same,
and output means for receiving the digital information read out from said
tracks and for expanding the same into a substantially continuous stream,
said output means comprising a first in first out memory for receiving
digital information being read out, an up-down counter for registering the
full condition of said memory, and circuit means responsive to the
conditions of the last mentioned up-down counter for controlling readout
so that said memory fills during reading of an information track and may
be continuously read out at a predetermined lower readout rate.
4. The apparatus according to claim 3 wherein said circuit means includes a
clock generator, a second counter for counting a number of digital clock
bits corresponding to a predetermined track length, and comparison means
for comparing an output of said up-down counter with an output of said
second counter to control the speed of readout of said tracks.
5. Apparatus for reading a record, said record including a plurality of
separated tracks of recorded digital information on a record medium, said
apparatus comprising:
means for reproducing the digital information in said tracks including
means for reading said tracks as separate segments with time gaps
therebetween,
and means for expanding the digital information in said tracks to produce a
substantially continuous flow of information, said means for expanding
information comprising a first in first out memory for receiving digital
information being read out, an up-down counter for registering the full
condition of said memory, and circuit means responsive to the condition of
the last mentioned up-down counter for controlling readout of said tracks
so that said memory fills during reading of an information track and may
be continously read out at a predetermined lower rate.
6. The apparatus according to claim 5 wherein said circuit means includes a
clock generator, a second counter for counting a number of digital clock
bits corresponding to a predetermined track length, and comparison means
for comparing an output of said up-down counter with an output of said
second counter to control the speed of readout of said tracks.
7. Recording and reproducing apparatus comprising:
a record medium capable of receiving and recording information in a
plurality of separated tracks,
means for recording and reproducing digital information in said tracks
comprising a single rotatable scanner, wherein said information is
recorded as a series of segments corresponding to said tracks, and
including input means comprising a first in first out memory for receiving
a continous flow of digital information, an up-down counter for
registering full and empty conditions of said memory, a clock signal
generator, and circuit means responsive to said full and empty conditions
for controlling the clock generator signal to withdraw information from
said memory for recording said information when said memory is full and
emptying the memory during the period of a desired information track,
and output means for reading out the digital information from said tracks
and for expanding the same in time into a substantially continuous stream.
8. The apparatus according to claim 7 wherein said circuit means includes a
second counter for counting a number of digital clock bits corresponding
to a predetermined track length, and comparison means for comparing an
output of said up-down counter with an output of said second counter to
control the rate of said clock generator.
9. Recording and reproducing apparatus comprising:
a record medium capable of receiving and recording information in a
plurality of separated tracks,
means for recording and reproducing digital information in said tracks
comprising a single rotatable scanner, wherein said information is
recorded as a series of segments corresponding to said tracks,
and output means for receiving the digital information read out from said
tracks as separate segments with time gaps therebetween and for expanding
the same in time into a substantially continuous stream, said output means
comprising a first in first out memory for receiving digital information
being read out, an up-down counter for registering the full condition of
said memory, and circuit means responsive to the condition of the last
mentioned up-down counter for controlling readout so that said memory
fills during reading of an information track and may be continuously read
out at a predetermined lower readout rate.
10. The apparatus according to claim 9 wherein said circuit means includes
a clock generator, a second counter for counting a number of digital clock
bits corresponding to a predetermined track length, and comparison means
for comparing an output of said up-down counter with the output of said
second counter to control the speed of readout by said scanner.
11. Recording and reproducing apparatus comprising:
an elongated record medium capable of receiving and recording information,
optical scanner means for recording and reproducing digital information in
the form of a series of digital spots in separate tracks substantially
crossways of said record medium,
means for producing relative movement between said record medium and said
optical scanner means in a direction substantially longitudinal of said
record medium,
input circuit means for receiving a substantially continuous flow of said
digital information, and for separating the same into compressed segments
corresponding to said tracks for recording the same, said input circuit
means comprising a first in first out memory for receiving a continuous
flow of digital information, an up-down counter for registering full and
empty conditions of said memory, a clock signal generator, and circuit
means responsive to said full and empty conditions for controlling the
clock generator signal to withdraw information from said memory for
recording said information when said memory is full and emptying the
memory during the period of a desired information track,
and output means for receiving the digital information read out from said
track by said optical scanner means and for expanding the same into a
substantially continuous stream.
12. The apparatus according to claim 11 wherein said output means comprises
a first in first out memory for receiving information being reproduced
from said optical scanner means, an up-down counter for registering the
full condition of said memory, and circuit means responsive to the
condition of the last mentioned up-down counter for controlling readout so
that said memory fills during reading of an information track and may be
continuously read out at a predetermined lower readout rate.
13. The apparatus according to claim 11 wherein said circuit means includes
a second counter for counting a number of digital clock bits corresponding
to a predetermined track length, and comparison means for comparing an
output of said up-down counter with an output of said second counter to
control the rate of said clock generator.
14. Recording and reproducing apparatus comprising:
an elongated record medium capable of receiving and recording information,
optical scanner means for recording and reproducing digital information in
the form of a series of digital spots in separate tracks substantially
crossways of said record medium,
means for producing relative movement between said record medium and said
optical scanner means in a direction substantially longitudinal of said
record medium,
input circuit means for receiving a substantially continuous flow of said
digital information, and for separating the same into compressed segments
corresponding to said tracks for recording the same,
and output means for receiving the digital information read out from said
tracks by said optical scanner means and for expanding the same into a
substantially continuous stream, said output means comprising a first in
first out memory for receiving information being read out by said optical
scanner means, an up-down counter for registering the full condition of
said memory, and circuit means responsive to the condition of the last
mentioned up-down counter for controlling the rate of readout by said
optical scanner means so that said memory fills during reading of an
information track and may be continuously read out at a predetermined
lower rate.
15. The apparatus according to claim 14 wherein said circuit means includes
a clock generator, a second counter for counting a number of digital clock
bits corresponding to a predetermined track length, and comparison means
for comparing an output of said up-down counter with an output of said
second counter to control the speed of readout of said optical scanner
means. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
Frequent need arises for bringing about relative synchronization between
different sources of information. For example, it often happens that a TV
program source is, say, one-half field later than another, and/or the time
relationship may drift slowly. At present there is no way to correct the
difference so that different sources can be used on the same program.
Moreover, there are several TV standards in the world. U.S. and Japan use
525 lines, 60 fields per second, the NTSC standard. In Europe, a common
system is the 625 lines, 50 fields system of PAL. A simple system does not
exist for converting from one frequency standard to another.
Also, systems employed for delayed broadcast or "stop action" can be
relatively complicated and costly, as when magnetic recording and playback
apparatus is employed. Moreover, with magnetic recording and playback,
generally a minimum delay is required between recording and playback so
that the respective recording and playback heads can be physically
accommodated along the magnetic recording medium.
Optical recording and playback of digital information advantageously solves
some of the foregoing problems, but digital recording can involve close
mechanical tolerances which make it difficult to take proper advantage
thereof.
SUMMARY OF THE INVENTION
First and second optical means are suitably disposed relative to a record
medium suitable for receiving and recording electromagnetic information.
The first optical means records the information via a first optical path,
and the second optical means reads the recorded information via a second
optical path. These optical means have a predetermined simultaneous
relationship with respect to the recording medium, and means are employed
for coordinating the first and second optical means for simultaneous
operation. Thus, the second optical means may read out information at a
predetermined delayed time after recording takes place, or means may
provide relative movement between the first and second optical means
whereby the reading rate is different from the recording rate.
The first and second optical means suitably comprise optical scanners
simultaneously disposed with respect to a recording medium which is
recorded upon by a recording light means and which rapidly records the
information for playback.
According to the present invention, an optical scanner or optical scanners
produce tracks of information across the moving recording medium wherein
the scanned information is broken into recording lines extending across
the recording medium. Electronic means is provided for supplying an
overscan gap between lines, i.e. to and from the edge of the recording
medium, wherein data is compressed while recording into lines and then
expanded upon readout by the same scanner or a different scanner. A high
density of recording can be provided without encountering tolerance
problems in recording and reading the separate recording lines extending
across the recording medium.
It is therefore an object of the present invention to provide an improved
system for playback of recorded information.
Another object of the present invention is to provide improved means for
recording and playback of information.
A further object of the present invention is to provide an improved system
for recording information in recording lines having a scanning gap
therebetween wherein information is expanded for readout into a continuous
stream.
The present invention, both as to organization and method of operation,
together with further advantages and objects thereof can best be
understood in reference to the following description taken in connection
with the accompanying drawings wherein like reference characters refer to
like elements.
DRAWINGS
FIG. 1 is a schematic side view, partially in cross section, of recording
and playback apparatus;
FIG. 2 is a plan view of the FIG. 1 apparatus;
FIG. 3 is a view of recording scanner according to the FIG. 1 apparatus,
the view being taken at 3--3 in FIG. 1;
FIG. 4 is a schematic view of an optical deflection device;
FIG. 5 is side view, partly in cross section, of another recording and
playback apparatus;
FIG. 6 is a side view, partially in cross section, of yet another recording
and playback apparatus;
FIG. 7 is a block diagram of electronic circuitry suitably employed in
recording information according to the present invention;
FIG. 8 is a block diagram of electronic circuitry for playback of
information according to the present invention;
FIG. 9 is a diagram illustrating the wave form of typical recorded
information;
FIG. 10 is a plan view of a recording medium according to the present
invention;
FIG. 11 is a block diagram of an additional circuit which may be used in a
television transcoding operation; and
FIG. 12 is a schematic side view, partially in cross section, of apparatus
according to yet a further embodiment.
DETAILED DESCRIPTION
Referring to the drawings and particularly to FIGS. 1 through 3, an
apparatus includes a first optional scanner 10 and a second optical
scanner 12 which are adapted to scan beams of electromagnetic energy, e.g.
light beams, across a record medium 14. A record medium 14 is suitably a
tape unreeled from reel 16, passing between capstan rollers 18, 20 and 22,
24 in the direction of the arrow, and received onto a pickup reel 26.
Capstan rollers 18 and 22 are respectively empowered by servo motors 28
and 30 (see FIG. 2), and have a contoured surface for "dishing" a record
medium 14, as illustrated in FIG. 3, whereby the light beam from scanner
10 can be accurately focused upon the record medium.
The record medium should be self-developing. There are several classes of
photosensitive materials that are satisfactory, i.e., dry silver,
free-radical, vesicular (Kalvar), thermal destruction (melt or vaporize),
and photochromic. The dry silver and free-radical systems require a
further treatment of heat if a permanent record is desired. Hence, for
these materials a heating element (not shown) is employed subsequent to
recording by means of scanner 10. The various rapid light recording media
are known by those skilled in the art.
Scanner 10 suitably comprises a metal cylinder 28 journaled in bearings 31
supported in turn by an outer cylindrical body 32 which also supports
motor coils 34. Hence, the cylindrical body 28 forms the rotor of a motor
such as a synchronous hysteresis type.
Upon one end of cylinder 28 is secured a head 36 which rotates and carries
a plurality of objective lenses 38 around the forward periphery thereof.
As illustrated in FIG. 3, six evenly spaced objective lenses 38 may be
located at the forward end of head 36 and disposed in an angular forward
wall of the head for scanning across the record medium 14 as the cylinder
28 is rotated about its axis which is parallel to the direction of motion
of the record medium 14.
The light for scanner 10 is provided by a laser 40 positioned axially
forward of the scanner 10 and adapted for projecting a beam of light 42
substantially along the axis of the scanner through a modulator 44 to an
optical tube 46 which is suitably located partially within cylinder 28.
The optical tube 46 includes lenses 48 and 50 and a pinhole aperture 52
therebetween. Lens 50 directs light from the pinhole upon a pyramidal
shaped mirror 54 which is secured to the forward end of head 36 and
functions to direct the light to the lenses 38 in succession as head 36
rotates. Thus, since six objective lenses 38 are located in head 36,
pyramidal mirror 54 is formed with six facets, each one of which
successively reflects light to a lens 38 for scanning a light beam 55
across record medium 14.
The light beam is imaged to a narrow track across the record medium 14.
Thus, the recording track is about one micron in width, and the spacing
between track centers, as the recording medium 14 is moved longitudinally,
is about three microns. The total length of track required depends upon
the bandwidth and recording format selected. With a film having a width of
approximately two inches, about 4.5 inches of record medium per minute is
required for television recording or about eleven feet per thirty minute
period. A 1000 foot reel of record film would last about two days. This
recording density represents an improvement of more than one hundred as
compared with the recording density for television information on magnetic
tape, for example.
The recording apparatus according to the present invention generally
contemplates digital recording of information wherein modulator 44 is
either in an on condition or an off condition as controlled by a binary
type input on lead 56 coupled via amplifier 58 to the modulator. In such
case, the recording is from the type set forth in my U.S. Pat. No.
3,501,586 granted Mar. 17, 1970, and entitled "Analog to Digital to
Optical Photographic Recording and Playback System", wherein information
is expressed in digital spots. However, the apparatus according to the
present invention may also suitably record analog information wherein an
analog input is received on lead 56.
According to this embodiment, a second or reading scanner 12 is disposed
along the record medium 14 for reading out the recorded information at a
variably preselected time after the same is recorded on the medium. The
second scanner 12 is substantially identical to the recording scanner and
includes a cylinder 60 journaled in bearings 62 secured to an outer
cylindrical member 64 which also supports motor coils 66. A head 68
supports pyramidal mirror 70 at the forward end thereof for directing
light through a plurality of objective lenses 72 positioned in a forward
angular wall of the head. The number of lenses 72 may be the same as the
number of lenses 38 in the recording scanner, i.e. six, in the instance of
the particular example.
A playback laser 74 directs a beam of light through an optical tube 76
disposed along the axis of scanner 12 and including lenses 78 and 80 and a
pinhole aperture 82 located therebetween. Lens 80 directs the beam from
the pinhole aperture to the pyramidal mirror 70 for successively directing
the light beam toward the particular objective lens 72 which is tracing
across the record medium 14.
In the case of tube 76, a further deflection device 84 is housed between
the pinhole aperture 82 and lens 80. This deflection device is further
disclosed and claimed in my co-pending application Ser. No. 522,702 filed
Nov. 11, 1974, and entitled "Optical Fiber Deflection Device," (now U.S.
Pat. No. 3,941,927 granted Mar. 2, 1976). A typical embodiment is
illustrated herein in FIG. 4. Light is directed from lens 78, FIG. 1,
axially along an optical fiber 86 which is shown in end view in FIG. 4. It
is desirable to deflect the optical fiber 86 in mutually perpendicular
directions indicated by arrows 88 and 90. A first coil 92 is disposed upon
a first magnetic metal core, the ends of which form pole pieces 94 and 96
on opposite sides of optical fiber 86. A further metal magnetic core has
pole pieces 98 and 100 located on either side of the optical fiber, along
a direction orthogonal to the first set of pole pieces, while a coil 102
is disposed around the second magnetic metal core. The optical fiber 86 is
made of light transparent glass or plastic and is provided with coating of
metal or other conducting material which is electrically connected at one
end by a lead wire 104 to a battery 106, and the opposite terminal of
which is grounded. The opposite end of the coating on the optical fiber is
also grounded so a current flows therealong. First ends of the coils 92
and 102 are connected to a tracking control 108 which controllably
provides current through the coils for deflecting the optical fiber 86 to
the desired extent. In this manner, the exact positioning of the light
beam passing through lenses 72 onto the record medium 14 can be
controlled. Other deflection structures are disclosed in the
aforementioned application Ser. No. 522,702, and moreover, a servo
controlled mirror device or light refracting plate, servo controlled by a
galvanometer movement or the like, can be also utilized. The purpose of
this structure, which will hereinafter more fully appear, is in the first
instance for tracking the light beam 110 along the particular recorded
track across the record medium 14.
As the beam 110 tracks along the line or track of record information, a
variable amount of light will be transmitted through the record medium 14,
the intensity of laser 74 being such that it will not produce further
recording. The transmitted light is picked up by fiber optic light
collector tube 112 which extends along under the path of the light beam
110 and conveys the light to detector 114 which includes photoelectric
means for providing an output indicated at 116. The detector also suitably
includes a tracking control circuit performing the function of tracking
control circuit 108 in FIG. 4 and which may be of the type shown in
pending U.S. application Ser. No. 483,131 of R. A. Walker, filed June 26,
1974 (now U.S. Pat. No. 3,919,697 granted Nov. 11, 1975). Alternatively,
tracking circuitry of the type illustrated in my aforementioned U.S. Pat.
No. 3,501,586 may be utilized, wherein motion of the light beam 110 back
and forth across the recorded track is detected. In any case, a servo
output is produced on lead 118 connected to servo mechanism driving
circuitry 120 and 122 connected respectively to deflection device 84 and
to motor 124 which is adapted to move scanner 12 along record medium 14 as
hereinafter more fully described. The servo mechanism driving circuitry
120 controls deflection device 84 for adjusting the light beam 110 in a
direction for following along the previously recorded track across the
record medium 14. An integrating circuit 126 also couples servo mechanism
circuitry 120 in driving relation to servo mechanism driving circuitry 122
so that an averaged or prolonged error from a predetermined beam position
causes motor 124 to move the scanner 12 physically relative to scanner 10.
The deflection device 84 causes the light beam 110 to follow the recorded
trace in spite of small errors in recording medium motion, scanner motion,
vibration, etc.
Referring particularly to FIG. 2, the scanner 12 is mounted upon a bracket
128 slideable upon fixed rails 130 which are parallel to the path of
record medium 14. Motor 124 turns a feed screw 132 which engages a mating
threaded portion in bracket 128, whereby rotation of the feed screw
physically moves scanner 12 in a direction longitudinal of the record
medium 14. Rotation of motor 124 also rotates shaft encoder 135 which
indicates the location of scanner 12 relative to scanner 10.
A primary function of the apparatus as thus far illustrated is the delayed
reproduction of information recorded upon medium 14. By positioning the
scanner 12 along the track 130, it is possible to produce a predetermined
amount of delay in reproduction, relative to recording, from substantially
zero delay to delays involving several minutes or longer. Thus, if scanner
12 is moved relative to scanner 10 to nearly an abutting position, it can
be seen that beam 110 can be focused on recording medium 14 at a point
nearly coincident with the recording beam 55. A magnetic recording and
reproduction system would not allow such latitude in regard to the timing
of the reproduction because of the necessity of proximity of the magnetic
writing and reading heads to the recording medium causing some minimum
delay between recording and reading. In other words, the magnetic writing
and reading heads cannot be located at the same place, and mechanical
interference results in a necessary delay in reading what has been
recorded. However, in the case of optical writing and reading, the reading
beam can be directed toward substantially the same location on the medium
where writing is taking place, or at any selected point thereafter.
On the other hand, the recording density is so great in the present system
that relative movement of the scanner 12 away from scanner 10 produces a
considerable delay. The apparatus is suitably employed for producing a
desired delay in reproduction, or for reproducing information at a
different rate from the rate at which the information was recorded. Thus,
the scanner 12 can be gradually moved along tracks 130, under the control
of the servo mechanism circuitry 122, to produce a desired output rate.
The head 68 is rotated under the control of servo mechanism 134 coupled in
driving relation to motor coils 66 (in FIG. 1), and responsive to an
output system clock so that the scanner 12 successively scans across
recorded tracks at a rate dictated by such external clock. In the short
run, servo mechanism driving circuitry 120 causes deflection device 84 to
keep the beam 110 on track. A continual output from driving circuitry 120
through integrator 126 is produced as the deflection device 84 diverges
continually from a "normal" position, causing servo mechanism 122 to drive
the motor 124 for producing gradual movement of the scanner 12 in a
desired direction. If the scanning rate of the reading scanner 12 is lower
than the scanning rate of recording scanner 10, then the scanner 12 will
gradually move to the left in FIG. 2, or further away from scanner 10.
Generally, the length of possible movement provided will be sufficient to
accommodate prolonged movement of scanner 12 without running the same
mechanically too great a distance. Alternatively, a pair of systems as
illustrated may be employed in the alternative so that a scanner 12 of a
second overall system can take over the reading of recorded information
while the scanner 12 of the first system is moved back.
The converse situation arises when the information is being read out at a
faster rate than is being recorded, in which case scanner 12 will move
ever closer to scanner 10. A dual system may then again be employed for
reading with a second reading scanner while a first reading scanner is
moved away from its recording scanner 10.
Alternatively, rather than using a plurality of complete systems, a single
system can be employed which occasionally skips information or replays
information. Thus, in the case of television recording, error can be
accumulated for a complete frame. Shaft encoder 135 detects a
predetermined physical movement of scanner 12 in one direction or the
other, and roughly determines when one frame of error has been
accumulated. Control unit 292 thereupon controls deflection device 86 to
move beam 110 along the tape the distance of one recorded frame. Suitably,
each scanning line across the record medium 14 comprises 25 television
horizontal raster lines, so that there are 21 scanning lines across the
record medium per frame in the 525 line NTSC system. For the PAL system 25
such scanning lines across the medium are involved. The scanning device 84
is servoed by way of circuitry 120 for predetermined movement in either a
backward or forward direction depending upon the direction of accumulated
error. The actual scanning movement to skip a frame or for the replaying
of a frame may take place coincident with the end of a frame as detected
by detector 114 and supplied to control unit 292. The light beam 110 will
then be locked in a different track at a different position from the
"normal" position for deflection device 84, and consequently, servo
circuitry 120 controls servo circuitry 122 via integrator 126 for
providing the reverse movement of the entire scanner 12. While skipping or
replaying of only one frame is discussed, it is clear the system may skip
or replay more than one frame or another predetermined body of information
as desired.
This system is useful for transsynchronization, i.e. for coupling one TV
signal into a system which is, say, one-half field later than the other,
or with a drifting relationship therebetween. The nonsynchronized source
is recorded according to its own input data clock which suitably controls
the speed of rotation of scanner 10, and played back in synchronism with
the desired output clock which controls servo circuitry 134, e.g. as
hereinafter described in connection with the FIG. 8 circuit.
For transcoding, i.e. for converting from one television standard to
another, the TV signal with the differing standard is recorded by means of
scanner 10 and played back in synchronism with the desired standard by
means of scanner 12. The frequency standard problems can be handled in the
same manner as transsynchronization described above. For "cosmetic"
purposes it may be desirable to include the circuit of FIG. 11 in output
lead 116 so that lines can be repeated as desired for filling in gaps.
Thus, the PAL system includes a greater number of scanning lines, and it
is desired to add lines in converting from NTSC to PAL. Referring to FIG.
11, delay line 293 suitably comprises a digital register having a length
to accommodate data for one TV horizontal line. Both delayed and
nondelayed outputs are supplied to selector and summing circuit 294. In
converting from NTSC to PAL, circuit 294 suitably selects a given line,
say line 1 of a raster in nondelayed form. For output raster line 2,
circuit 294 selects the sum of information from the delayed and nondelayed
circuit paths. For output raster line 3 scanner 12 is directed via control
circuit 292 to rescan input raster line 2 by means of changing the
position of deflection device 86. Then a third input raster line is read
through circuit 294 without delay. Alternatively, horizontal lines may be
merely stored and repeated, or the output presentation may be altered in
analog fashion.
For transcoding from PAL to NTSC, the selecting circuit 294 may be employed
for deleting some horizontal lines. In order to bridge the gap caused by
skipped lines, circuitry of the type illustrated in FIG. 11 may be
employed for summing lines. For example, a given raster line 1 is selected
by circuit 294 in nondelayed form. Input raster line 2 is skipped, and for
a second output raster line, the combination of input raster line 3 and
input raster line 1 as delayed are added together in circuit 294. Input
raster line 4 then becomes output raster line 3 and the sequence is
continued. To avoid vertical compression of the image various portions of
each horizontal line may be deleted in random fashion. For this purpose, a
horizontal line is stored while logical means may be employed for deleting
selected portions thereof.
It is desirable to change the position of deflection device 86 of scanner
12 for skipping a line so that the flow of output information is
continuous despite deletion of information. Alternatively, a first in,
first out memory of the type hereinafter more fully described may be
employed for converting a flow of discontinuous data into a flow of
continuous data. It is understood that various approaches for cosmetic
alteration of transcoded data may be employed and are understood by those
skilled in the art.
The system according to the present invention is clearly useful for
delaying an ordinary live television broadcast for substantially any
period of time up to several minutes. This is of value in live program
production, wherein the director could "preview" the broadcast a few
seconds or minutes before transmission. Also, a "stop action" facility is
readily obtainable with the system according to the present invention. The
deflection device 84 is controlled to reread a given frame or given series
of frames wherein the deflection device 84 causes nearly immediate
movement of light beam 110 along the record medium 14. The deflection
device is controlled from control unit 292 via servo mechanism 120 for
replaying the desired portions of the tape for a period of time up to
several minutes, whereby stop action or instant replay is secured. With
each replay, the deflection device 84 is directed farther from its
"normal" position, whereby servo mechanism 122 is commanded via
integrating circuit 126 to cause overall movement of scanner 12 in the
direction away from scanner 10. Slower integration may be employed for
this replay type of operation to prevent excessive oscillation of scanner
12 back and forth along the record medium.
The system may be employed for indexing and editing purposes, as when the
recorded information is in digital form. The control unit 292, in such
case, suitably comprises a mini-computer adapted to count and keep track
of the frames on record medium 14. Servo motors 28 and 30 (in FIG. 2)
operating under the control of servo mechanism circuitry 288 are suitably
operated at variable speeds under the supervision of control unit 292 (in
FIG. 1) for the location of certain frames and the running of the record
medium at various speeds in forward and reverse directions, e.g. over the
entire span of tape carried by reels 16 and 26. An editor, viewing a TV
monitor or the like receiving an input from line 116, reproduces sections
of the record medium at any speed, e.g. on a slow motion or frame-by-frame
basis to select the exact frame which may be of interest. Each frame may
be marked or premarked on the record medium with a different numerical
designation, or the frames may be counted and stored in a relative manner
by the computer control. When a whole program's worth of segments have
been found and selected, they may be then re-indexed and played out in
sequence to another recorder, suitably duplicating the apparatus of FIGS.
1-3. Each system can operate on a start-stop basis, i.e. wherein the
record medium is brought up to speed within one frame time (30
milliseconds) and wherein the deflection device 84 is employed to
compensate for film acceleration so that start and stop is effectively
instantaneous. That is, the deflection device 84 is controlled together
with motion of the record medium 14 so that the deflection device traces
along the recorded track until the record medium comes up to speed.
To measure the motion of the record medium, it is desirable to provide a
velocity detector 290 coupled to servo mechanism circuit 288. A velocity
detector may, for example, be light sensitive and responsive to doppler
frequency shift, with monochromatic light being used.
A further system is illustrated in FIG. 5 and includes a disc-type
recording scanner 136 and a disc-type reading scanner 138 disposed on
opposite sides of a record medium which may comprise film or a plurality
of plates 190, 192 adapted to have information recorded thereon in
substantially the same manner as record medium 14 in the previous
embodiment. However, in this embodiment the recording tracks across the
medium will be arcuate shaped rather than substantially straight lines as
in the case of the previous embodiment. Scanner 136 comprises a disc
portion 140 carrying a plurality of objective lenses 142 eve | | |
