CA1131775A - Track skipper for video disc player - Google Patents
Track skipper for video disc playerInfo
- Publication number
- CA1131775A CA1131775A CA339,383A CA339383A CA1131775A CA 1131775 A CA1131775 A CA 1131775A CA 339383 A CA339383 A CA 339383A CA 1131775 A CA1131775 A CA 1131775A
- Authority
- CA
- Canada
- Prior art keywords
- stylus
- track
- carriage
- electromagnet
- arm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 241000630329 Scomberesox saurus saurus Species 0.000 title abstract description 13
- 238000004804 winding Methods 0.000 claims description 7
- 241001422033 Thestylus Species 0.000 abstract description 63
- 230000000694 effects Effects 0.000 description 7
- 238000013519 translation Methods 0.000 description 3
- 230000014616 translation Effects 0.000 description 3
- 239000004020 conductor Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000011324 bead Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229940000425 combination drug Drugs 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B21/00—Head arrangements not specific to the method of recording or reproducing
- G11B21/02—Driving or moving of heads
- G11B21/08—Track changing or selecting during transducing operation
- G11B21/081—Access to indexed tracks or parts of continuous track
- G11B21/083—Access to indexed tracks or parts of continuous track on discs
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B3/00—Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
- G11B3/02—Arrangements of heads
- G11B3/10—Arranging, supporting, or driving of heads or of transducers relatively to record carriers
- G11B3/12—Supporting in balanced, counterbalanced or loaded operative position during transducing, e.g. loading in direction of traverse
- G11B3/125—Supporting in balanced, counterbalanced or loaded operative position during transducing, e.g. loading in direction of traverse by using electric or magnetic means
- G11B3/127—Providing horizontal force, e.g. anti-skating force
Landscapes
- Moving Of Heads (AREA)
- Recording Or Reproducing By Magnetic Means (AREA)
- Feeding And Guiding Record Carriers (AREA)
Abstract
-12- RCA 69,112 TRACK SKIPPER FOR VIDEO DISC PLAYER
ABSTRACT OF THE DISCLOSURE
In a video disc player, a carriage is subject to translatory motion in correlation with radial motion of a playback stylus relative to a disc record disposed on a rotatable turntable. A stylus arm carrying the stylus at one end thereof has the other end secured to the carriage by means of a compliant rubber coupler. A magnetic element is disposed on the stylus arm near its free end.
An electromagnet is fixedly mounted in the carriage adjacent to the stylus arm-mounted, magnetic element. The electromagnet is selectively actuated to cause a change in the radial location of the stylus.
ABSTRACT OF THE DISCLOSURE
In a video disc player, a carriage is subject to translatory motion in correlation with radial motion of a playback stylus relative to a disc record disposed on a rotatable turntable. A stylus arm carrying the stylus at one end thereof has the other end secured to the carriage by means of a compliant rubber coupler. A magnetic element is disposed on the stylus arm near its free end.
An electromagnet is fixedly mounted in the carriage adjacent to the stylus arm-mounted, magnetic element. The electromagnet is selectively actuated to cause a change in the radial location of the stylus.
Description
1~31775 1 -1- RCA 69,112 T~CK SKIPPER FOR VIDEO DISC PLAYER
_ _ . _ . .
This invention pertains to an apparatus utilized in the playback of a video disc record, and more particularly, 5 to an apparatus for selectively repositioning a player stylus from one convolution to another of a signal-encoded spiral track disposed on the record surface.
U. S. Patent No. 3,842,194, issued on Oetober 15, 1974 to Jon K. Clemens, is illustrative of a video dise playbaek system of the variable capacitance form. In an arrangement therein disclosed, an information track incorp~
orates geometric variations in the bottom of a spiral groove in a disc, the surface of which comprises conductive material covered with a thin coating of dielectric material. Vari-5 ations in the capacitance presented between a conductiveelectrode on a tracking stylus and the conductive material of the disc occur as the disc is rotated by a supporting turntable. The capacitance variations are sensed to recover the recorded information.
In certain applications of video dise systems such as, for example, the Clemens type, it may be desirable to provide repeat plays of the displayed image. That is, to repetitively provide output signals of basieally the same displayed image on an assoeiated television monitor.
Sueh image repeat play may be desirable for allowing a viewer to observe a partieular image for relatively long lengths of time.
A further desirable feature for ineorporation with a video dise player is the abili-ty to provide rapid forward motion or reverse motion of the displayed image. A
rapid forward funetion is partieularly useful for quickly seanning information recorded on the video dise. A reverse motion funetion may also be utilized for aiding in data retrieval, and is partieularly useful as a teaehing aid for reviewing an instruetional pieture sequenee reeorded on the dise.
Moreover, in the playbaek of video dise reeords eonditions are oeeasionally eneountered when -the presenee of some form of defeet, for example a defeet in the dise ' 1 -2- RCA 69,112 groove, causes the player stylus to skip across convolutions of the information track rather than follow the successive convolutions of the spiral track in a regular progression 5 toward one extremity thereof. For example, as the defect is encountered, the stylus may be deflected into repeat traversal of one or more previously traversed convolutions.
In some instances, the outward deflection of the stylus is repeated for a substantial number of successive encounters 10 with the defect. This condition is herein referred to as a "locked groove" condition, producing repetitive replay of the same recorded information, with annoying effects on picture display and accompanying sound reproduction.
To provide special effect features (e.g., repeat 15 play, fast forward, reverse, trick plays, etc.) and to advance the stylus out of a locked groove, it is desirable to provide a selectively actuated apparatus for reposi-tioning the pickup stylus from one convolution to another of the record spiral track.
U.S. Patent No. 3,963,861, issued on June 15, 1976 to H.N. Crooks, and U.S. Patent No. 3,993,863, issued on November 23, 1976 to Leedom, et al., describe illustrative groove skipping systems. In these systems, selectively actuated piezoelectric bimorph elements cause lateral shift-25 ing of the stylus-carrying end of the stylus arm.
An advantageous arrangement for selectively indexing the stylus from one convolution to another is herein described. Pursuant to this invention, the apparatus includes a playback stylus attached to the stylus arm near 30 its free end. A rubber coupler secures the other end of the stylus arm to a carriage, which is subject to trans-lation in correlation with the motion of the stylus toward the record center during playback. Disposed near the free end of the stylus arm is a magnetic element. An electro-35 magnet is fixedly mounted in the carriage in the vicinityof the magnetic element. Actuation of the electromagnet results in a change in the radial location of the stylus in the appropriate direction.
A desirable feature of this invention is that : i 113~775 1 -3- RCA 69,112 the net force experienced by the stylus arm is relatively independent of the position of the stylus. For example, in the event of a number of locked grooves occurring on a 5 record, the stylus arm is repeatedly advanced toward the record center by the indexing apparatus of this invention~
The movement of the stylus arm toward the record center reduces the spacing between the stylus arm-mounted, magnetie element and the electromagnet, and also develops a mechanieal 10 bias urging the stylus arm away from the record center because of the rear rubber coupler. This mechanical bias is automatically compensated for in the instant apparatus sinee the force on the stylus arm is increased automatieally beeause of the reduction in the spacing between the magnetie 15 element and the electromagnet.
In accordance with a further embodiment, an electromagnet is plaeed on eaeh side of the stylus arm-mounted, magnetic element to selectively effect forward (i.e. toward the record center) as well as reverse motion 20 of the stylus. Alternately, the combination of a stylus arm-mounted, permanent magnet and a single electromagnet ean be substituted for the foregoing arrangement to effeet forward and reverse motion of the stylus.
In the drawings:
FIGURE 1 is a bloek diagram representation of a video disc player ineorporating the traek skipper apparatus of this invention;
FIGURE 2 illustrates a piekup cartridge suitable for use in the video disc player of FIGURE l;
FIGURE 3 shows an enlarged view of a portion of the piekup eartridge of FIGURE 2;
FIGURE 4 depiets a earriage having a compartment for reeeiving the piekup eartridge of FIGURES 2 and 3;
FIGURE 5 is an enlarged view of a portion of 35 the earriage of FIGURE 4;
FIGURE 6 diagrammatieally illustrates another embodiment of the track skipper apparatus of this invention suitable for use with the video dise player of FIGURE l;
FIGURES 7 and 8 show a still further embodiment .:
.
11317~5 1 -4- RCA 69,112 of the track skipper apparatus of this invention also suit-able for use with the video disc player of FIGURE l; and FIGURE 9 illustrates another embodiment of the invention suitable for use with the video disc player of FIGURE 1.
FIGURE 1 represents a video disc playback system incorporating circuitry utilized for operating the track skipper apparatus of this invention. The circuitry shown in FIGURE 1 is of the type described in the Crooks t3,963,861~
and Leedom et al. (3,993,863) patents. A video disc player 10 has a turntable 12 for rotatably supporting a video disc 14 having a spiral information track disposed thereon.
A carriage 16, having a compartment for removably receiving a pickup cartridge 18, is subject to translation in synch-ronism with the motion of the playback stylus towward the record center during playback. The carriage drive mechanism illustratively may be of the type described in U.S. patent No. 3,870,835 (Stave).
Capacitance variations between the record and an electrode incorporated in the playback stylus are coupled to a signal developing circuit 20 wherein decoding occurs and a composite video signal developed. The signals developed by the signal developing circuit 20 are coupled to a signal processing circuit 22 and a sync stripping circuit 24. The signal processing circuit 22 rearranges the luminance and chrominance constituents of the video signal into a Eormat (such as NTSC) suitable for decoding by a television receiver 26. Sync signals provided by the sync stripping circuit 24 are coupled to a sync counting circuit 28, which in response to signals from a control unit 30 provides an output signal which repetitiously occurs at a predetermined whole number division of the frequency 35 of the applied vertical sync signals. A drive pulse gener-ating circuit 32 receives signals from both the sync counting circuit 28 and the control circuit 30, and responsively provides appropriate control pulses. These control pulses are applied to the track skipper apparatus for selectively 40 causing the playback stylus to skip in the forward and the .
- - - .
1 -5- RCA 69,112 reverse direction depending upon the manner in which the control pulses are applied.
To provide the repeat play function, the playback stylus is repeatedly repositioned to an adjacent outer convolution of the spiral track disposed on the record once each revolution of the record by means of the instant track skipper apparatus. The drive pulse generating circuit 32 responsive to the control circuit 30 and the sync counting circuit 28, provides appropriate pulses at the once-around rate of the turntable to cause the stylus to skip backward once each revolution.
The fast forward function may be implemented by causing the pickup stylus to skip forward, for example, once every one-half revolution of the record. SimilarlY
reverse motion may be effected by causing the stylus to skip backward once every one-half convolution of the record.
For locked groove clearance purposes, detection circuitry 34 of the type delineated in U.S. patent No. 3,963,860 (Burrus) may be utilized to detect the occurren~ of a locked groove condition. The stylus is advanced in the forward direction by actuation of the subject track skipper apparatus upon generation of a locked groove recognition pulse. A track skipper apparatus in accordance with the instant invention will now be described in detail with reference to FIGURES 2 - 5. Shown in FIGURE 2 is the pickup cartridge 18. The cartridge comprises a stylus arm 50 which carries at the free end 30 thereof a stylus holder 52. A pickup stylus 54 is secured to the stylus holder 52. An extension S6, disposed on the stylus holder 52, is interposed between a pair of non-magnetic, plastic bumpers (not shown) mounted on the carriage 16. The bumpers serve to limit side-to-side excursion of 35 the stylus 54.
The other end of the stylus arm 50 is secured to a connector plate 62 via a compliant coupler 64. A flexible diaphragm 66 secures the connector plate 62 to the cartridge body 68. A U-shaped spring 70 serves to retain the stylus :: -: - , :, '~ . , ~:~:--~13~775 1 -6- RCA 69,112 assembly within the confines of the cartridge 18 during storage and handling. A conductive leaf spring 72 connects an electrode incorporated in the stylus (not shown) to a terminal (not shown) disposed on the cartridge 18.
Cartridge 18 is removably received in the carriage 16 (FIGURE 4). As previously indicated, the carriage is subject to translation toward the record center in cor-relation with the radial motion of the stylus during play-back, for example, in the manner described in U.S. patent No. 3,870,835 (Stave).
Mounted in the carriage 16 are a stylus arm lifting/lowering mechanism 82 and an arm stretcher apparatus 84. The stylus arm lifting/lowering mechanism is of the type described in U.S. patent No. 4,053,161 issued to J. C. Bleazey, et al. on October 11, 1977. The lifting/
lowering mechanism serves to gently lower the pickup stylus 54 on the video disc for playback. The mechanism 82 also serves to lift the stylus away from the record, for example, for allowing the stylus to clear the peripheral bead of the record as the carriage is translated from the off-record, rest position to the on~record, play position, or for example, when the player is in the pause mode.
As shown in FIGURE 4, the arm stretcher apparatus 84 is provided with a support 86. When the cartridge 18 is installed in the compartment 80 and the lid 88 of the carriage 16 is closed, a mechanism 90, responsive to the lid movement, effects engagement between the connector plate 62 of the cartridge and the support 86 of the arm stretcher. The mechanism 90 also serves to effect engage-ment between the cartridge terminal and another terminal 92 disposed on the carriage 16 for electrically connecting the stylus electrode to the rest of the player circuitry. The support 86 of the arm stretcher apparatus 84 imparts translatory motion to the stylus arm in a manner that opposes cyclical deviations in the stylus/record relative velocity during playback. The cyclical deviations in the stylus/record relative velocity result from a number of sources, for example, eccentricity, warp, etc. U.S. patent ' ~
~13~7~75 1 -7- RCA 69,112 ~o. 3,983,318 (Miller) describes an illustrative arm stretcher apparatus.
The bottom wall of the carriage has an opening 94 for permitting the playback stylus to protrude there-through during playback to effect stylus/record engagement when the stylus arm is lowered by the stylus arm lifting/
lowering mechanism 82.
A lever (not shown) disposed on -the lid 88 serves to defeat the U-shaped, stylus arm retaining spring allowing the stylus arm to rest on an arm 96 of the lifting/lowering mechanism 82, when the lid is closed after installing the cartridge 18 in the carriage compartment.
Secured to the stylus arm 50, near its free end, is a magnetic element 100 (FIGURES 2 and 3). An electro-magnet 102 is fixedly mounted in the carriage such that the pole faces 104 and 106 thereof are disposed adjacent to the stylus arm-mounted magnetic element. A winding 108 (FIGURE 5) of the electromagnet is coupled to the drive pulse generating circuit 32 of FIGURE 1. Actuation of the electromagnet causes the poles to exert a pull on the stylus arm-mounted magnetic element, which results in a radially inward displacement (i.e., forward motion) of the stylus.
If both forward and backward motion of the stylus is de-sired, an electromagnet may be provided on each side of the magnetic element in the manner described subsequently.
In the embodiment shown in FIGURE 6, a stylus arm 200 carrying a stylus 202 at one end thereof, has the 3 other end secured to a pickup cartridge 204 by a compliant rubber coupler 206. The pickup cartridge is received in a translatably-mounted carriage 208. A magnetic element 210 is secured to the stylus arm 200 at a distance from the stylus 202. An electromagnet 212 is fixedly mounted in the carriage in the vicinity of the magnetic element.
The electromagnet 212 comprises a horseshoe-shaped core 214 having pole faces 216 and 218, and a winding 220 disposed about the central portion of the core. An actuating signal, for example, indicative of a backward groove skip due to a locked groove, is applied to the winding to advance ~.
- ~:: . ..
11317~;~5 1 -8- RCA 69,112 the stylus in the forward direction in order to avoid undesirable repeat play. The number of convolutions that are skipped every time the electromagnet is pulsed is a function of the magnitude of the actuation pulse and the distance between the magnetic element 210 and the electro-magnet 212.
A still further embodiment of this invention is shown in FIGURES 7 and 8. As shown therein, electromagnets 300 and 302 are disposed in the carriage 304 on opposite sides of a magnetic element 306 mounted on the stylus arm 308. Forward and backward motion of the stylus can be obtained by energizing the inner and the outer electro-magnets 300 and 302 respectively. Alternately, the com-bination of a stylus arm-mounted, permanent magnet 400 and a single electromagnet 402 can be substituted, as shown in FIGURE 9, for the foregoing arrangement to effect forward and reverse motion of the stylus. The direction of motion of the stylus is controlled by the direction of the current flow through the winding 404 disposed about the core 406 of the electromagnet.
In a video disc system which utilizes a grooved information track, the application of control signals to the electromagnet and the resulting magnetic forces which are applied to the permanent magnet positioned on the stylus arm cause the stylus arm to experience the desired radial movement. When the stylus arm is thus being radially moved it is believed that the stylus tip rides up the groove wall in one convolution and down the groove wall of the adjacent convolution, or, if a large signal is applied, down the groove wall several convolutions away from the starting convolution. As a result of the position-ing of the permanent magnet on the stylus arm, or, at least in the near vicinity of the plane in which the stylus arm lies during playback, the application of the magnetic forces causes the generally lateral movement in the radial direction of the stylus tip in the manner described.
The track skipper arrangement described herein will be useful in many video disc systems over and above ' ` . ' ~ '' .
, 1 -9- RCA 69, 112 the general system environment described herein for illus-trative purposes. Without limitation, the present track skipper may be utilized in systems with grooved as well as grooveless discs.
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., ... . .
.~ :
- - --.
_ _ . _ . .
This invention pertains to an apparatus utilized in the playback of a video disc record, and more particularly, 5 to an apparatus for selectively repositioning a player stylus from one convolution to another of a signal-encoded spiral track disposed on the record surface.
U. S. Patent No. 3,842,194, issued on Oetober 15, 1974 to Jon K. Clemens, is illustrative of a video dise playbaek system of the variable capacitance form. In an arrangement therein disclosed, an information track incorp~
orates geometric variations in the bottom of a spiral groove in a disc, the surface of which comprises conductive material covered with a thin coating of dielectric material. Vari-5 ations in the capacitance presented between a conductiveelectrode on a tracking stylus and the conductive material of the disc occur as the disc is rotated by a supporting turntable. The capacitance variations are sensed to recover the recorded information.
In certain applications of video dise systems such as, for example, the Clemens type, it may be desirable to provide repeat plays of the displayed image. That is, to repetitively provide output signals of basieally the same displayed image on an assoeiated television monitor.
Sueh image repeat play may be desirable for allowing a viewer to observe a partieular image for relatively long lengths of time.
A further desirable feature for ineorporation with a video dise player is the abili-ty to provide rapid forward motion or reverse motion of the displayed image. A
rapid forward funetion is partieularly useful for quickly seanning information recorded on the video dise. A reverse motion funetion may also be utilized for aiding in data retrieval, and is partieularly useful as a teaehing aid for reviewing an instruetional pieture sequenee reeorded on the dise.
Moreover, in the playbaek of video dise reeords eonditions are oeeasionally eneountered when -the presenee of some form of defeet, for example a defeet in the dise ' 1 -2- RCA 69,112 groove, causes the player stylus to skip across convolutions of the information track rather than follow the successive convolutions of the spiral track in a regular progression 5 toward one extremity thereof. For example, as the defect is encountered, the stylus may be deflected into repeat traversal of one or more previously traversed convolutions.
In some instances, the outward deflection of the stylus is repeated for a substantial number of successive encounters 10 with the defect. This condition is herein referred to as a "locked groove" condition, producing repetitive replay of the same recorded information, with annoying effects on picture display and accompanying sound reproduction.
To provide special effect features (e.g., repeat 15 play, fast forward, reverse, trick plays, etc.) and to advance the stylus out of a locked groove, it is desirable to provide a selectively actuated apparatus for reposi-tioning the pickup stylus from one convolution to another of the record spiral track.
U.S. Patent No. 3,963,861, issued on June 15, 1976 to H.N. Crooks, and U.S. Patent No. 3,993,863, issued on November 23, 1976 to Leedom, et al., describe illustrative groove skipping systems. In these systems, selectively actuated piezoelectric bimorph elements cause lateral shift-25 ing of the stylus-carrying end of the stylus arm.
An advantageous arrangement for selectively indexing the stylus from one convolution to another is herein described. Pursuant to this invention, the apparatus includes a playback stylus attached to the stylus arm near 30 its free end. A rubber coupler secures the other end of the stylus arm to a carriage, which is subject to trans-lation in correlation with the motion of the stylus toward the record center during playback. Disposed near the free end of the stylus arm is a magnetic element. An electro-35 magnet is fixedly mounted in the carriage in the vicinityof the magnetic element. Actuation of the electromagnet results in a change in the radial location of the stylus in the appropriate direction.
A desirable feature of this invention is that : i 113~775 1 -3- RCA 69,112 the net force experienced by the stylus arm is relatively independent of the position of the stylus. For example, in the event of a number of locked grooves occurring on a 5 record, the stylus arm is repeatedly advanced toward the record center by the indexing apparatus of this invention~
The movement of the stylus arm toward the record center reduces the spacing between the stylus arm-mounted, magnetie element and the electromagnet, and also develops a mechanieal 10 bias urging the stylus arm away from the record center because of the rear rubber coupler. This mechanical bias is automatically compensated for in the instant apparatus sinee the force on the stylus arm is increased automatieally beeause of the reduction in the spacing between the magnetie 15 element and the electromagnet.
In accordance with a further embodiment, an electromagnet is plaeed on eaeh side of the stylus arm-mounted, magnetic element to selectively effect forward (i.e. toward the record center) as well as reverse motion 20 of the stylus. Alternately, the combination of a stylus arm-mounted, permanent magnet and a single electromagnet ean be substituted for the foregoing arrangement to effeet forward and reverse motion of the stylus.
In the drawings:
FIGURE 1 is a bloek diagram representation of a video disc player ineorporating the traek skipper apparatus of this invention;
FIGURE 2 illustrates a piekup cartridge suitable for use in the video disc player of FIGURE l;
FIGURE 3 shows an enlarged view of a portion of the piekup eartridge of FIGURE 2;
FIGURE 4 depiets a earriage having a compartment for reeeiving the piekup eartridge of FIGURES 2 and 3;
FIGURE 5 is an enlarged view of a portion of 35 the earriage of FIGURE 4;
FIGURE 6 diagrammatieally illustrates another embodiment of the track skipper apparatus of this invention suitable for use with the video dise player of FIGURE l;
FIGURES 7 and 8 show a still further embodiment .:
.
11317~5 1 -4- RCA 69,112 of the track skipper apparatus of this invention also suit-able for use with the video disc player of FIGURE l; and FIGURE 9 illustrates another embodiment of the invention suitable for use with the video disc player of FIGURE 1.
FIGURE 1 represents a video disc playback system incorporating circuitry utilized for operating the track skipper apparatus of this invention. The circuitry shown in FIGURE 1 is of the type described in the Crooks t3,963,861~
and Leedom et al. (3,993,863) patents. A video disc player 10 has a turntable 12 for rotatably supporting a video disc 14 having a spiral information track disposed thereon.
A carriage 16, having a compartment for removably receiving a pickup cartridge 18, is subject to translation in synch-ronism with the motion of the playback stylus towward the record center during playback. The carriage drive mechanism illustratively may be of the type described in U.S. patent No. 3,870,835 (Stave).
Capacitance variations between the record and an electrode incorporated in the playback stylus are coupled to a signal developing circuit 20 wherein decoding occurs and a composite video signal developed. The signals developed by the signal developing circuit 20 are coupled to a signal processing circuit 22 and a sync stripping circuit 24. The signal processing circuit 22 rearranges the luminance and chrominance constituents of the video signal into a Eormat (such as NTSC) suitable for decoding by a television receiver 26. Sync signals provided by the sync stripping circuit 24 are coupled to a sync counting circuit 28, which in response to signals from a control unit 30 provides an output signal which repetitiously occurs at a predetermined whole number division of the frequency 35 of the applied vertical sync signals. A drive pulse gener-ating circuit 32 receives signals from both the sync counting circuit 28 and the control circuit 30, and responsively provides appropriate control pulses. These control pulses are applied to the track skipper apparatus for selectively 40 causing the playback stylus to skip in the forward and the .
- - - .
1 -5- RCA 69,112 reverse direction depending upon the manner in which the control pulses are applied.
To provide the repeat play function, the playback stylus is repeatedly repositioned to an adjacent outer convolution of the spiral track disposed on the record once each revolution of the record by means of the instant track skipper apparatus. The drive pulse generating circuit 32 responsive to the control circuit 30 and the sync counting circuit 28, provides appropriate pulses at the once-around rate of the turntable to cause the stylus to skip backward once each revolution.
The fast forward function may be implemented by causing the pickup stylus to skip forward, for example, once every one-half revolution of the record. SimilarlY
reverse motion may be effected by causing the stylus to skip backward once every one-half convolution of the record.
For locked groove clearance purposes, detection circuitry 34 of the type delineated in U.S. patent No. 3,963,860 (Burrus) may be utilized to detect the occurren~ of a locked groove condition. The stylus is advanced in the forward direction by actuation of the subject track skipper apparatus upon generation of a locked groove recognition pulse. A track skipper apparatus in accordance with the instant invention will now be described in detail with reference to FIGURES 2 - 5. Shown in FIGURE 2 is the pickup cartridge 18. The cartridge comprises a stylus arm 50 which carries at the free end 30 thereof a stylus holder 52. A pickup stylus 54 is secured to the stylus holder 52. An extension S6, disposed on the stylus holder 52, is interposed between a pair of non-magnetic, plastic bumpers (not shown) mounted on the carriage 16. The bumpers serve to limit side-to-side excursion of 35 the stylus 54.
The other end of the stylus arm 50 is secured to a connector plate 62 via a compliant coupler 64. A flexible diaphragm 66 secures the connector plate 62 to the cartridge body 68. A U-shaped spring 70 serves to retain the stylus :: -: - , :, '~ . , ~:~:--~13~775 1 -6- RCA 69,112 assembly within the confines of the cartridge 18 during storage and handling. A conductive leaf spring 72 connects an electrode incorporated in the stylus (not shown) to a terminal (not shown) disposed on the cartridge 18.
Cartridge 18 is removably received in the carriage 16 (FIGURE 4). As previously indicated, the carriage is subject to translation toward the record center in cor-relation with the radial motion of the stylus during play-back, for example, in the manner described in U.S. patent No. 3,870,835 (Stave).
Mounted in the carriage 16 are a stylus arm lifting/lowering mechanism 82 and an arm stretcher apparatus 84. The stylus arm lifting/lowering mechanism is of the type described in U.S. patent No. 4,053,161 issued to J. C. Bleazey, et al. on October 11, 1977. The lifting/
lowering mechanism serves to gently lower the pickup stylus 54 on the video disc for playback. The mechanism 82 also serves to lift the stylus away from the record, for example, for allowing the stylus to clear the peripheral bead of the record as the carriage is translated from the off-record, rest position to the on~record, play position, or for example, when the player is in the pause mode.
As shown in FIGURE 4, the arm stretcher apparatus 84 is provided with a support 86. When the cartridge 18 is installed in the compartment 80 and the lid 88 of the carriage 16 is closed, a mechanism 90, responsive to the lid movement, effects engagement between the connector plate 62 of the cartridge and the support 86 of the arm stretcher. The mechanism 90 also serves to effect engage-ment between the cartridge terminal and another terminal 92 disposed on the carriage 16 for electrically connecting the stylus electrode to the rest of the player circuitry. The support 86 of the arm stretcher apparatus 84 imparts translatory motion to the stylus arm in a manner that opposes cyclical deviations in the stylus/record relative velocity during playback. The cyclical deviations in the stylus/record relative velocity result from a number of sources, for example, eccentricity, warp, etc. U.S. patent ' ~
~13~7~75 1 -7- RCA 69,112 ~o. 3,983,318 (Miller) describes an illustrative arm stretcher apparatus.
The bottom wall of the carriage has an opening 94 for permitting the playback stylus to protrude there-through during playback to effect stylus/record engagement when the stylus arm is lowered by the stylus arm lifting/
lowering mechanism 82.
A lever (not shown) disposed on -the lid 88 serves to defeat the U-shaped, stylus arm retaining spring allowing the stylus arm to rest on an arm 96 of the lifting/lowering mechanism 82, when the lid is closed after installing the cartridge 18 in the carriage compartment.
Secured to the stylus arm 50, near its free end, is a magnetic element 100 (FIGURES 2 and 3). An electro-magnet 102 is fixedly mounted in the carriage such that the pole faces 104 and 106 thereof are disposed adjacent to the stylus arm-mounted magnetic element. A winding 108 (FIGURE 5) of the electromagnet is coupled to the drive pulse generating circuit 32 of FIGURE 1. Actuation of the electromagnet causes the poles to exert a pull on the stylus arm-mounted magnetic element, which results in a radially inward displacement (i.e., forward motion) of the stylus.
If both forward and backward motion of the stylus is de-sired, an electromagnet may be provided on each side of the magnetic element in the manner described subsequently.
In the embodiment shown in FIGURE 6, a stylus arm 200 carrying a stylus 202 at one end thereof, has the 3 other end secured to a pickup cartridge 204 by a compliant rubber coupler 206. The pickup cartridge is received in a translatably-mounted carriage 208. A magnetic element 210 is secured to the stylus arm 200 at a distance from the stylus 202. An electromagnet 212 is fixedly mounted in the carriage in the vicinity of the magnetic element.
The electromagnet 212 comprises a horseshoe-shaped core 214 having pole faces 216 and 218, and a winding 220 disposed about the central portion of the core. An actuating signal, for example, indicative of a backward groove skip due to a locked groove, is applied to the winding to advance ~.
- ~:: . ..
11317~;~5 1 -8- RCA 69,112 the stylus in the forward direction in order to avoid undesirable repeat play. The number of convolutions that are skipped every time the electromagnet is pulsed is a function of the magnitude of the actuation pulse and the distance between the magnetic element 210 and the electro-magnet 212.
A still further embodiment of this invention is shown in FIGURES 7 and 8. As shown therein, electromagnets 300 and 302 are disposed in the carriage 304 on opposite sides of a magnetic element 306 mounted on the stylus arm 308. Forward and backward motion of the stylus can be obtained by energizing the inner and the outer electro-magnets 300 and 302 respectively. Alternately, the com-bination of a stylus arm-mounted, permanent magnet 400 and a single electromagnet 402 can be substituted, as shown in FIGURE 9, for the foregoing arrangement to effect forward and reverse motion of the stylus. The direction of motion of the stylus is controlled by the direction of the current flow through the winding 404 disposed about the core 406 of the electromagnet.
In a video disc system which utilizes a grooved information track, the application of control signals to the electromagnet and the resulting magnetic forces which are applied to the permanent magnet positioned on the stylus arm cause the stylus arm to experience the desired radial movement. When the stylus arm is thus being radially moved it is believed that the stylus tip rides up the groove wall in one convolution and down the groove wall of the adjacent convolution, or, if a large signal is applied, down the groove wall several convolutions away from the starting convolution. As a result of the position-ing of the permanent magnet on the stylus arm, or, at least in the near vicinity of the plane in which the stylus arm lies during playback, the application of the magnetic forces causes the generally lateral movement in the radial direction of the stylus tip in the manner described.
The track skipper arrangement described herein will be useful in many video disc systems over and above ' ` . ' ~ '' .
, 1 -9- RCA 69, 112 the general system environment described herein for illus-trative purposes. Without limitation, the present track skipper may be utilized in systems with grooved as well as grooveless discs.
, .
.
.
.
.
., ... . .
.~ :
- - --.
Claims (2)
1. Apparatus in a system for recovering prerecorded information from a disc record having a spiral information track by a track-following stylus when stylus/record relative velocity is established; wherein normal operation of said system involves sensing of said prerecorded information along successive convolutions of said spiral track in a regular progression toward one extremity;
comprising:
a carriage subject to translatory motion in correlation with radial motion of said track-following stylus during playback; said carriage having an opening in a bottom wall thereof;
a stylus arm having a longitudinal axis, and carrying said track-following stylus at one end thereof;
means for yieldably securing the end of said stylus arm remote from said one end to said carriage;
said yieldable securing means permitting said track-follow-ing stylus to protrude through said opening when said stylus arm is lowered during playback;
a magnetic element secured to said stylus arm near said one end thereof;
an electromagnet for providing a controllable magnetic field of a given polarity when energized;
means for mounting said electromagnet to said carriage in the vicinity of said magnetic element; and means for selectively energizing said electromagnet to cause a shift in the radial location of said track-following stylus.
-11- RCA 69,112
comprising:
a carriage subject to translatory motion in correlation with radial motion of said track-following stylus during playback; said carriage having an opening in a bottom wall thereof;
a stylus arm having a longitudinal axis, and carrying said track-following stylus at one end thereof;
means for yieldably securing the end of said stylus arm remote from said one end to said carriage;
said yieldable securing means permitting said track-follow-ing stylus to protrude through said opening when said stylus arm is lowered during playback;
a magnetic element secured to said stylus arm near said one end thereof;
an electromagnet for providing a controllable magnetic field of a given polarity when energized;
means for mounting said electromagnet to said carriage in the vicinity of said magnetic element; and means for selectively energizing said electromagnet to cause a shift in the radial location of said track-following stylus.
-11- RCA 69,112
2. The apparatus as defined in Claim 1 wherein said magnetic element is permanently magnetized in a given direction; said electromagnet comprising a core and a winding disposed about said core; said apparatus further including means for passing current through said winding;
the direction of motion of said stylus being determined by the direction of the current passing through said winding.
the direction of motion of said stylus being determined by the direction of the current passing through said winding.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7844739 | 1978-11-16 | ||
| GB44739-78 | 1978-11-16 | ||
| US39,359 | 1979-05-15 | ||
| US06/039,359 US4262174A (en) | 1979-05-15 | 1979-05-15 | Track skipper for video disc player |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1131775A true CA1131775A (en) | 1982-09-14 |
Family
ID=26269598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA339,383A Expired CA1131775A (en) | 1978-11-16 | 1979-11-07 | Track skipper for video disc player |
Country Status (11)
| Country | Link |
|---|---|
| AU (1) | AU525918B2 (en) |
| CA (1) | CA1131775A (en) |
| DE (1) | DE2946015A1 (en) |
| DK (1) | DK485279A (en) |
| ES (1) | ES485997A1 (en) |
| FR (1) | FR2441900A1 (en) |
| HK (1) | HK49883A (en) |
| IT (1) | IT1193335B (en) |
| PL (1) | PL123280B1 (en) |
| SE (1) | SE7909299L (en) |
| SG (1) | SG30183G (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2470489B1 (en) * | 1979-11-19 | 1986-01-17 | Rca Corp | BIDIRECTIONAL PULSE GENERATOR FOR DRIVING A DEVICE TRANSDUCER OF A READ NEEDLE |
| US4375094A (en) * | 1980-11-10 | 1983-02-22 | Rca Corporation | Apparatus for advancing a video disc pickup transducer beyond a disc record defect |
| JPS57150173A (en) * | 1981-03-12 | 1982-09-16 | Victor Co Of Japan Ltd | Reproducer for disc shape information recording medium |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5048820A (en) * | 1973-04-11 | 1975-05-01 | ||
| JPS594782B2 (en) * | 1977-03-14 | 1984-01-31 | 日本ビクター株式会社 | Signal pickup device for rotating recording media playback device |
| US4170783A (en) * | 1977-03-14 | 1979-10-09 | Victor Company Of Japan, Ltd. | Signal pickup device for reproducing an information signal recorded on a track of a rotary recording medium |
| JPS53113505A (en) * | 1977-03-15 | 1978-10-04 | Victor Co Of Japan Ltd | Pickup device for rotary recording medium reproducing signal |
| AU530389B2 (en) * | 1978-05-22 | 1983-07-14 | Rca Corp. | Recording/playback apparatus facilitating track skipping |
| CA1133633A (en) * | 1978-11-16 | 1982-10-12 | Elvin D. Simshauser | Track skipper apparatus for video disc player |
-
1979
- 1979-11-07 CA CA339,383A patent/CA1131775A/en not_active Expired
- 1979-11-09 AU AU52693/79A patent/AU525918B2/en not_active Ceased
- 1979-11-09 SE SE7909299A patent/SE7909299L/en not_active Application Discontinuation
- 1979-11-13 IT IT7927256A patent/IT1193335B/en active
- 1979-11-14 DE DE19792946015 patent/DE2946015A1/en not_active Withdrawn
- 1979-11-15 ES ES485997A patent/ES485997A1/en not_active Expired
- 1979-11-15 PL PL1979219641A patent/PL123280B1/en unknown
- 1979-11-15 FR FR7928212A patent/FR2441900A1/en active Pending
- 1979-11-15 DK DK485279A patent/DK485279A/en not_active Application Discontinuation
-
1983
- 1983-05-31 SG SG301/83A patent/SG30183G/en unknown
- 1983-11-03 HK HK498/83A patent/HK49883A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| HK49883A (en) | 1983-11-11 |
| AU525918B2 (en) | 1982-12-09 |
| IT7927256A0 (en) | 1979-11-13 |
| DE2946015A1 (en) | 1980-05-29 |
| IT1193335B (en) | 1988-06-15 |
| DK485279A (en) | 1980-05-17 |
| AU5269379A (en) | 1980-05-22 |
| SE7909299L (en) | 1980-05-17 |
| PL219641A1 (en) | 1980-08-11 |
| SG30183G (en) | 1984-04-19 |
| ES485997A1 (en) | 1980-09-01 |
| FR2441900A1 (en) | 1980-06-13 |
| PL123280B1 (en) | 1982-10-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |