GB2060950A - Adaptive stylus translator - Google Patents

Adaptive stylus translator Download PDF

Info

Publication number
GB2060950A
GB2060950A GB8033020A GB8033020A GB2060950A GB 2060950 A GB2060950 A GB 2060950A GB 8033020 A GB8033020 A GB 8033020A GB 8033020 A GB8033020 A GB 8033020A GB 2060950 A GB2060950 A GB 2060950A
Authority
GB
United Kingdom
Prior art keywords
stylus
kicker
disc
signals
signal
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.)
Granted
Application number
GB8033020A
Other versions
GB2060950B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from US06/086,245 external-priority patent/US4330879A/en
Application filed by RCA Corp filed Critical RCA Corp
Publication of GB2060950A publication Critical patent/GB2060950A/en
Application granted granted Critical
Publication of GB2060950B publication Critical patent/GB2060950B/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/102Programmed access in sequence to addressed parts of tracks of operating record carriers
    • G11B27/105Programmed access in sequence to addressed parts of tracks of operating record carriers of operating discs
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B17/00Guiding record carriers not specifically of filamentary or web form, or of supports therefor
    • G11B17/005Programmed access to indexed parts of tracks of operating discs, by guiding the disc
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B21/00Head arrangements not specific to the method of recording or reproducing
    • G11B21/02Driving or moving of heads
    • G11B21/04Automatic feed mechanism producing a progressive transducing traverse of the head in a direction which cuts across the direction of travel of the recording medium, e.g. helical scan, e.g. by lead-screw
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B21/00Head arrangements not specific to the method of recording or reproducing
    • G11B21/02Driving or moving of heads
    • G11B21/08Track changing or selecting during transducing operation
    • G11B21/081Access to indexed tracks or parts of continuous track
    • G11B21/083Access to indexed tracks or parts of continuous track on discs
    • G11B21/085Access to indexed tracks or parts of continuous track on discs with track following of accessed part
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00Record carriers by type
    • G11B2220/20Disc-shaped record carriers

Landscapes

  • Optical Recording Or Reproduction (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)
  • Knitting Machines (AREA)

Abstract

An adaptive eg video disc record stylus kicker (46) system for inducing limited pickup or stylus (14) translations radially across the disc record (12). Control circuitry (54) responsive to disc track and disc angular sector identification signals automatically calibrates the kicker activation signals (51) to produce a desired kicker induced stylus translation. That is, the control circuitry responsive to these track identification signals and to player commands (53) evaluates the error between actual kicker induced stylus translations and the programmed kicker induced stylus translations. A microprocessor (56) establishes a table containing kicker control signals for driving the kicker in each sector of the disc. For a given kicker induced stylus translation, the error is calculated between the actual stylus translation and the programmed stylus translation and the control signal for the respective sector is adjusted accordingly. Subsequently, the control signals for each of the other sectors are altered proportional to the adjustment made to the particular control signal in accordance with a correlation function. The system operates to correct mistracking (identification signals do not appear in the correct sequence) due, e.g. to record defects. <IMAGE>

Description

SPECIFICATION Adaptive stylus translator This invention relates to apparatus utilized in the playback of a disc record and more particularly to apparatus for repositioning a player signal pickup stylus from one convolution of a signal encoded' information track disposed on the disc to another.
Certain capacitive video disc systems incorporate record discs with information recorded by means of geometric variations in a conductive medium disposed proximate the bottom of a track in the form of a smooth spiral groove on the surface of a record disc. The bulk of the record disc may comprise a homogeneous conductive material with a thin dielectric layer disposed on its outer surfaces. A pickup or signal stylus supported at one end of a stylus arm, and having a conductive electrode engages and tracks the groove. The stylus electrode and conductive record material form a capacitance, which capacitance varies spatially over the record in accordance with the geometric variations in the bottom of the groove.
Continuous capacitive changes resulting from rotating the disc to produce relative motion between the stylus and disc are detected and processed to produce video andor audio signals for reproduction.
Video disc systems of the aforementioned type may utilize disc records having groove densities in the order of four to eight thousand groove convolutions per inch, and in some cases, close to ten thousand groove convolutions per inch. A typical video disc record of this type may have a groove convolution spacing in the order of 2.7 microns. The fragile walls of relatively narrow grooves of the disc record cannot be dependably relied upon to pull the weight of the pickup arm assembly, around the pickup arm pivot support, across the entire recorded surface of the disc record. Also in video disc systems utilizing the variable capacitor concept, it is desirable for accurate reproduction of the prerecorded signals that the signal pickup electrode maintain a substantially constant attitude in the spiral groove.Therefore, the supporting structure includes a radial feed drive mechanism for traversing the supported end of the pickup arm in propertime relationship with the radial motion of the signal pickup tip engaged in the spiral groove so as to continuously maintain the longitudinal axis of the pickup arm substantially tangential to the spiral groove at the point of engagement.
Disc records having high groove densities are subject to occasional flaws causing premature termination of the spiral groove. Such premature termination frequently causes an outward translation of the stylus resulting in an undesired and annoying repetition of a particular groove convolution during disc playback (referred to as a locked track or groove). In order to correct for such outward stylus translation, certain playback apparatus incorporate systems for determining the occurrence of a locked groove and also incorporate a mechanism for imparting an inward motion to the stylus relative to the pickup arm support assembly. See for example U. S. Patent 3,963,861 entitled, "Disc Record Groove Skipper Apparatus", U.S.
Patent 3,963,860 entitled, "Locked Groove Detection and Correction in Video Disc Playback Apparatus", and U.S. Patent 4,183,059, issued January 8, 1980, entitled, "Track Skipper for a Video Disc Player," for representative stylus skipping mechanisms.
Because the dimensions of the stylus, groove, and groove pitch, etc., are particularly small and the dimensions of the stylus arm, carriage, disc record and the kicker mechanisms, etc. are relatively large, provision for mechanical adjustment of each kicker assembly with respect to its associated stylus assembly is desirable. This provision does not account for variations in the physical dimensions of grooves from disc record to disc record.
The present invention incorporates a means to automatically adapt each kicker apparatus to its associated stylus assembly and to the particular disc record being played. To facilitate kicker adaptation, groove identification signals are included in the information recorded on the disc. Control circuitry responsive to an interruption of progressive incrementing of the identification signals, actuates a programmable pulse generator to drive a stylus kicker mechanism in the appropriate direction. The pulse generator produces a first pulse of nominal amplitude to the kicker.
Depending upon the resulting stylus translation or lack thereof, the pulse generator is adjusted by the control circuitry to increase (decrease) the pulse amplitude in prescribed increments (decrements) until the desired translation is acquired for a single applied pulse to the kicker. The resulting pulse amplitude is thereafter established as the nominal value for the particular record disc being played.
That is, the control circuitry is to initiate a kicker induced stylus translation and calculate the error between the programmed kicker induced stylus translation and the actual kicker induced stylus translation. The control circuitry will then adjust the kicker energization signals in such manner to reduce the error and iterate this cycle until the actual kicker induced stylus translation corresponds with the programmed kicker induced stylus translation.
For the condition that the kicker will always be activated at the same disc angular coordinate, satisfactory performance is obtained from such a system. On the other hand, video disc systems which are required to produce kicker induced stylus translations at least at each angular occurrence of the vertical blanking interval of the recorded signal, require that the kicker system be calibrated for each of these points. It can readily be appreciated that a warped disc establishes varying stylus-disc interaction depending upon whether the stylus is in contact with a disc "high" point or "low" point. These interactions are manifested as variations in stylus-disc pressure which affect the stimulus required of the kicker to translate the stylus.Similarly groove eccentricities impose opposing mechanical biases at 180 increments which affect kicker drive requirements.
In accordance with a feature of the invention, control circuitry is programmed to divide the disc record in sectors. Said circuitry induces a partial kicker calibration for an arbitrary sector of the disc as described in the foregoing and applies the resultant calibration factor to each of the remaining sectors in accordance with an angularly dependent correlation function. Each time a particular sector undergoes either partial or complete calibration the new coefficients are translated to the remaining sectors via the correlation function. In this manner the total number of calibration operations are reduced and interference with normal record playback is reduced.
In the drawings: Figure 1 is a block diagram of a record disc playback system including an adaptive kicker; Figure 2 is a diagrammatic representation of a stylus-arm assembly having an electromagnetic kicker apparatus; Figure 3 is a block diagram of an adaptive stylus kicker system; Figures 4A and 4B illustrate programmable current sources; Figures 5A and 5B are graphic representations of the output signal responses for the pulse generator circuit of Figure 3 respectively with the circuits of Figures 4A and 4B substituted for the programmable current source; Figure 6 is a block diagram of an embodiment of the signal recognition circuit of Figure 3; and Figure 7 is a flow chart illustrating a sequence by which the system of Figure 3 adapts the stylus kicker to the physical parameters of the player/record system.
In the video disc playback system of Figure 1, player 10 has a turntable 11 for rotatably supporting a record disc 12 having an information track which may be spiral or concentric in form. Each track or convolution of the spiral track on the disc contains picture signal information inclusive of synchronization components plus information identifying the particular track. A stylus assembly 14 including a signal pickup stylus and a kicker apparatus, for imparting motion to translate the pickup stylus over one or more convolutions of the groove, is mounted in the carriage mechanism 13 for radial translation of the stylus assembly across the record.
Capacitance variations occurring between the stylus and the disc record are detected by pickup circuits 16 and applied to the video processor 18 to format the signal for display by a conventional TV receiver 20.
Control circuitry 25, responsive only to the track identification signal monitors the track numbers. Upon the occurrence of an undesired or anomalous stylus progression the control circuitry 25 applies a signal of a prescribed nominal value (analog or digital signal) to the pulse generator 28. Pulse generator 28 generates a pulse of appropriate shape and/or amplitude to energize the stylus kicker to translate the stylus a desired number of convolutions. If the stylus fails to move or skips too many convolutions the control circuitry 25 respectively increments or decrements the control signal value and initiates a further kick. The controller iterates through this process until the proper control signal is established to accomplish the particular stylus translation desired.
Several options are available regarding the time and manner of providing such adaptive stylus movement.
A first method is to perform kicker adaptation immediately upon the stylus engaging the record disc in a preplay band having information recorded for calibrating the player. Once the control pulse parameters are established they constitute fixed constants for the remainder of play of the particular disc.
A second method is to incorporate calibration of the kicker system as described immediately above with the added flexibility of having the system readapt the control pulse parameters whenever a kick produces improper results.
A third method is to have the system calibrate upon the first occurrence of an abnormal stylus progression.
Afourth method is to partially calibrate the kicker system for each occurrence of an abnormal stylus progression.
Figure 2 illustrates a stylus-kicker assembly. A stylus 35 having a signal pickup electrode thereon is contoured to engage the grooves 36 of record 12. Electrical contact to the electrode is made via flylead 38.
The flylead 38 also produces a degree of pressure between the stylus and the record. Stylus 35 is mounted to the free end of stylus arm 37, the opposite end of which is attached to the carriage assembly 40 by a compliant coupling 39 which permits limited freedom of movement of the stylus arm in three dimensions. A permanent magnet 45 is fixedly mounted to the stylus arm 37 relatively near the stylus and arranged so that substantially only one pole such as the North pole is immersed in the magnetic field lines emanating from the selectively energized electromagnets or coils 46 when the stylus is in the play position. The coils 46 having nonmagnetic cores are electrically connected to produce aiding fields to impart a radial movement to magnet 45 and consequently movement of the stylus when the coils are energized.
The partial schematic-partial block diagram of Figure 3 illustrates an adaptive kicker system for the player 10. In Figure 3 a microprocessor 56, assumed to include the requisite associative circuitry for normal operation responsive to system or program commands (53) from the player controls, monitors the stylus position via track identification signals and applies inward or outward kick signals in accordance with the mode of playback. For example, if a particular video frame is to be "frozen", at that point in the record playback, the stylus is kicked one convolution or track outward for each revolution of the disc. Where one frame is recorded in each convolution, nothing more need be done. Where several frames are recorded per convolution, additional apparatus may be used to avoid flicker in the output display.The microprocessor 56 receives track identification signals from the recognition circuit 54, calculates the proper stylus position and current errors in the stylus position and determines appropriate control signal adjustments to apply to the programmable pulse generator 28' and the switch 47 to reposition the stylus in the direction of the proper or the desired track. The pulse generator 28' produces a ramped voltage proportional to the control signal applied by the microprocessor via input bus 58. The pulse generator output signal at connection 51 is applied to the reversing switch 47 for application to the stylus kicker coil 46.The reversing switch 47, controlled by the microprocessor 56 via bus 57 governs the direction of current flow through the stylus kicker coil 46 and thereby the direction of the magnetic field created between the coils and consequently the direction of stylus movement.
The pulse generator 28' includes a current source circuit 49 providing a high impedance regulated current in a first mode and a low impedance connection to a reference potential in a second mode. When the current source is operated in the second mode the potential across capacitor 55 is clamped at the reference potential. Switching the current source 49 to its first mode causes the potential at connection 50 to monotonically increase in accordance with the charging rate of capacitor 55, i.e., V =1/C f I dt = "''c t11 where I is the amplitude of the current supplied by source 49, C is the capacitance value of capacitor 55 and t is the charging time.
The potential at connection 50 is buffered by amplifier 48 which generates the requisite range of output currents to drive the stylus kicker coil 46.
A particular embodiment of the current source 49 is illustrated in Figure 4A. A conventional current source 65 is serially connected in the collector circuit of transistor 66 between supply terminals 67 and 68. A positive control potential with respect to supply terminal 68, applied to control input 58 causes the transistor 66 to conduct, shunting all the current, I, from source 65 to terminal 68. A negative control potential turns transistor 66 off making the current I, available at output connection 50.
Figure 5A illustrates the response of the programmable pulse generator 28' with the Figure 4A circuit employed as the current source circuit. Figures 5A(a) illustrates the control pulse applied to the pulse generator and 5A(b) the pulse generator response. From equation (1) it is seen that for a particular constant current I, the duration "t" of the control pulse prog rams the output amplitude "v" of the pulse generator; the wider the negative control pulse the higher the output amplitude of the waveform "v".
Figure 4B is a binary programmable current source for producing 16 discreet output current levels.
Assuming each of the binary inputs 2 -23 have equal amplitude potentials, the current amplitudes of each of the respective current sources 107 to 110 is determined approximately by the input potential divided by the respective emitter resistor. The currents are summed and made available at connection 50. Since the resistors have binary weights, i.e., R, 2R, 4R, 8R, each of the currents from the respective sources 110, 109, 108 and 107 have binary weights making the combination a binary programmable current source Each of the sources 107 to 110 are conditioned to conduct by a logical low signal applied to their respective input connections. Consequently, a high signal applied to all binary inputs 20 to 23 turns the composite current source off and turns transistor 106 on via logical "AND" circuit 105.With transistor 106 conducting, the connection 50 is clamped to the reference potential at terminal 68.
Figure 5B illustrates the output response of the programmable pulse generator 28' with the Figure 4B circuit implementing the current source 49. In accordance with equation (1) it is noted that for a constant charging or integration time the output signal increases as the magnitude of current I is increased.
The recognition circuit 54' shown in Figure 6 provides identification data recorded in a particular format for use by the microprocessor. Consider, for example, a video disc in which information is recorded in a generally NTSC format having vertical and horizontal blanking intervals. Normally, the first 21 horizontal lines of each field of display contain no usable video information, thus that portion of a field may be used to contain track identification information. If there exist more than one field per track or convolution, and the fields are radially aligned from track to track so that each field of a track defines an angular sector of the disc, both track and sector information may be included. By way of example consider a record disc having a spiral groove with eight fields per convolution, the fields from convolution to convolution being aligned in eight 45 degree sectors.Assume also that on the nineteenth horizontal line of each field that a digital signal is recorded inclusive of an N bit recognition signal followed by an M bit identification signal.
The M bit identification signal identifies the convolution and the sector and the N bit recognition signal is used to alert the system that the subsequent M bits comprise useful data, e.g., track numbers. Assume that the maximum bit rate is equal to and synchronized with a fundamental system frequency such as the color burst frequency. Demodulated video signals from the video processor are applied via connection 26 to the clock generator 90 and threshold detector 91. Clock 90 generates a system clock, oscillating at a constant frequency equal to the requisite fundamental frequency and synchronized therewith, suitable for driving logic circuitry. The threshold circuit conditions the video signal, inclusive of the digital information to a two level signal having normal logic level amplitudes. The signal from threshold circuit 91 is sequenced, by the clock signal at connection 100, through the M bit serial-parallel shift register 92 and into the N bit matched filter 94. When ll sequential bits of the signal applied to filter 94 match a recognition signal programmed into the filter, the filter 94 outputs a correlation pulse on connection 96. The following M signal bits concurrently contained in register 92 are the track and sector information bits. M bits of information available from M parallel output connections 95 are latched and formatted for use by the microprocessor by LATCH circuit 93 responsive to the correlation pulse occurring on connection 96.
An alternative to using a recognition signal (code), to prompt the system, is to use circuitry to recognize the particular horizontal line in which the track identification information is recorded. One such system is described in the article "VIR II System" by S. K. Kim, published in the IEEE Transactions on Consumer Electronics, Vol. CE-24, No.3, August 1978.
The Figure 3 calculating means is illustrated as a microprocessor 56, though it may be implemented with a less powerful circuit or system dedicated solely to the task of generating the proper energization of a kicker assembly to achieve a desired stylus translation.
An illustrative sequence of events for determining the necessary kicker drive parameters is outlined by the Figure 7 flow chart. The routine does not include general system monitoring and kick control. This particular routine assumes that adaptive parameters will be generated on the first occurrence of a stylus kick and every kickthereafterwhich produces an improper stylus translation.
Once the adaptive sequence is initiated a first decision point 71 determines whether the system attempted a kick. If a kick was not attempted the system has no measured values to determine the performance of the kicker and the system exits the adaptive program. If a kick was attempted the system initializes (72) on the current groove convolution being tracked and calculates the number of groove convolutions skipped by subtracting the last-most previously detected groove convolution number from the current number. The system orients to whether an inward or outward kick was performed and whether an inward or outward stylus translation occurred. Having established these circumstances the particular kick control parameters are accessed for possible alteration.
A decision point (73) compares the immediate stylus translation with the minimum value programmed for the particular kick. If the stylus translation is less than the minimum set for the translation range programmed, the kicker control parameters are incremented (76). i.e.. the parameters are adjusted to produce a kick greater than the previous kick. Each increment to the control parameters may be a fixed constant, or for calculating means of sufficient computational power, the increments may be proportioned to the stylus translation error.
Once the control parameters are incremented, the new parameters are checked against a preset maximum (78). If the parameters equal or exceed the maximum, the routine is exited to preclude the system for performing an endless iteration possibly damaging the player or the disc record. On the other hand if the new control parameters are within the acceptable maximum limit, the incremental parameters are established (80} as the kicker control values for the kick corresponding to the particular program command.
The system then initiates a kick (81) to iterate the routine.
At decision point 73 a stylus translation exceeding the minimum causes a branching to decision point 75 which determines whether the stylus translation exceeded a preset range maximum. If it has not, then the system assumes it is operating with proper control parameters and the kicker adaptation is complete for the particular program command. If the stylus translation exceeds the maximum, the control parameters are decremented 1771 or adjusted to produce a lesser kick. The decremental parameters are checked against a preset minimum and saved (80) if they are in the acceptable range or else the routine is exited to prevent damage to the system.
A table of control parameters is maintained for each particular type of kick since the kicker requirements for different conditions may differ. The stylus arm dynamics for inward movement differ from the dynamics for outward movement as a result of inherent mechanical bias. Thus the kicker force and accordingly the kicker control parameters differ for inward and outward stylus translation. Additionally, a K groove inward stylus translation will necessitate a different drive parameter than an H groove inward stylus translation, etc., where K and H are arbitrary integers.
Record discs containing sector identifying data as well as track or groove convolution identifying data permit embellishments to the adaptive process. Warped records tend to cause varying degrees of stylus-disc pressure as the non-uniform surface passes under the relatively fixed position of the stylus assembly. As a practical result. the energy required to kick the stylus a given number of groove convolutions is related to the angular position of the disc. Similarly groove eccentricity creates kicker drive requirements which have an angular dependence. Thus if sector information is available to the kicker controller it is desirable to establish control pulse parameters for each sector. In implementing the sector dependent adaptive stylus kicker, an S entry table (where S equals the number of sectors on the disc) is maintained for each type of kick command.
The entries contain the control parameters to be used for energizing the kicker in each of the S sectors. When the stylus is to be kicked, the upcoming sector is used as an index to the table and the appropriate parameter is fetched and used to establish the kicker drive.
Angularly dependent kick pulse requirements due to eccentricity and warpage are not random, but generally approximate correlation functions. Groove eccentricity produces an outward stylus stylus arm bias at the angle of maximum runout and an inward stylus stylus arm bias 180 therefrom. Intermediate these extremes the bias goes to zero. It can easily be appreciated that the bias function approaches a cosine function, dependent on sector displacement. Similarly disc warpage has been found generally to assume a wavelike configuration having crests displaced 180 apart, and troughs displaced 180 apart. The functional relationship approaches that of a cosine of twice the angular displacement. The overall correlation function may be approximated by: F = G(1 +E cos tH5l c W cos 2(tis A 81 36us)) (2) where F is the correlation function, G is a nominal value or gain factor, E is a measure of eccentricity, W is a measure of warpage, Hs is angular position of the disc measured from an arbitrary sector and incremented each sector by 360/S degrees, and (Hs + n 360/S) is an angular displacement offset from Hs by integral numbers') of sectors S in degrees.
When the correlation function is used, the stylus is kicked and the stylus displacement is examined. If the kicker has not caused some minimum displacement, e.g., one groove convolution, the correlation function is added to the table of values in the appropriate angular offset. If the kick caused too great a displacement, the function is subtracted from the table of values with the appropriate angular offset. The result of using the correlation function is that single adaptive correction to one sector can be applied via the function to all of the sectors reducing the operational sequences to calibrate the kicker.
As a practical matter it is time-consuming to implement the equation (2) function containing both cosine functions. Thus kicker response is monitored for a constant kick control parameter applied to the kicker in a number of sectors to determine whether the correlation is dependent on the angular displacement or twice the angular displacement to ascertain the dominant features for the particular record. The correlation function is then reduced to F = G(1+Ecos(05) (3) or F = G(1 +W cos (2Hs))G(1+Wcos(2#5)) (4) Note the values of E and W can be experimentally determined for a particular system or they may be established as part of the adaptive process. For example consider that it has been established that the correlation function of equation 3 is dominant by generating a constant kick in each sector.The zero reference or starting angle is assigned to that sector which produces the smallest stylus translation. The remaining sectors are assigned angular values in increments of 360/S degrees (this assumes that kicks are generated in correspondingly similar areas in each sector). Assume a disc having four sectors, and that the stylus translations for consecutive sectors for a constant kick force are respectively Tot T1, T2 and T3. These translations are directly proportional to the sector dependent stylus resistance to lateral movement and therefore inversely dependent to the compensating correlation function, i.e., Tj = 1/G(1 +E cos Oi). Assume that translations To and T2 correspond to sectors assigned angular values of 0 and 1800 respectively.
Dividing the equation for To by the respective equation for T2 produces To = G(1 +E cos H2) (5) T2 G(1+EcosO0) solving forE E = (1 -T0/T2)/1T0/T2 cos #o - cos H2) (6) and substituting the values for Ho and H2 E = -(1 -T0/T2)(1 +To/T2) (7) The coefficient Win equation (4) may be determined in a similarfasion. The coefficient "G" is arbitrarily established at some nominal value known to produce stylus translation. Therefore, by making a series of measurements--one per sector with a constant kick force and performing the algebraic manipulation of equation (7) the correlation functions are determined.
In a typical system, however, determination of the coefficients "E", "G" and "W" would not be part of the adaptive process because the correlation function is desirably employed to reduce the number of experimental or measuring kicks applied to the system. Thus the coefficients would be preset to a statistically determined nominal value.
One skilled in the art of automatic control systems may readily devise variations of the invention without straying from the spirit of the invention and the claims should be construed in this light. For example, the particular pulse generator described may be substituted for by a programmable voltage source where the particular track skipper utilized is responsive to voltage signals. Also, the program sequence described by the flow chart is easily modified to include more or less system checks or functions.
A "kicker" in general impulsively moves a pickup to an adjacent track on a disc (eg radially translating a video disc stylus to a new groove).

Claims (12)

1. In combination with a disc record player mechanism for recovering information from disc records having information bearing tracks including track identification signals, the player mechanism having a carriage mechanism for translating a signal pickup stylus radially across said disc record and wherein the signal pickup stylus is mounted to a first end of a stylus arm, the second end of the stylus arm being supported in said carriage mechanism by a compliant coupling, an adaptive stylus translating apparatus comprising: translator means associated with said stylus arm and responsive to drive signals for selectively imparting translation of the stylus radially across said record:: a programmable pulse generator responsive to control signals for generating said drive signals applied to the translator means; control circuitry responsive to said track identification signals and to player program commands for generating said control signals, said control circuitry calculating the error between translator-induced stylus translations and programmed stylus translations and adjusting the control signals to reduce said error.
2. The apparatus as set forth in Claim 1 wherein the translator means comprises: a permanent magnet secured to the stylus arm near the first end thereof; a pair of spaced coils having non-magnetic cores for providing a magnetic field therebetween upon application of drive signals thereto; and means for mounting said pair of coils in fixed relation to said carriage such that said permanent magnet is disposed therebetween.
3. The apparatus as set forth in Claims 1 or 2 wherein the control circuitry comprises: means responsive to information recovered from the disc record for extracting the track identification signal therefrom, said means reproducing the track identification signal in a substantially digital format; and calculating means responsive to the track identification signal and to player program commands for generating a control signal to be applied to the programmable pulse generator, said calculating means determining the stylus translation imparted by the translator means in response to a particular control signal and altering said control signal in such manner to tend to produce a prescribed stylus translation in accordance with a particular program command.
4. The apparatus as set forth in Claim 3 wherein the control signal generated by the calculating means is a pulse of selectable duration and the programmable pulse generator generates a drive signal proportional to the duration of said control signal.
5. The apparatus as set forth in Claim 3 wherein the control signal is a binary coded signal.
6. The apparatus set forth in Claim 3 wherein the calculating means include a microprocessor.
7. In a system for recovering prerecorded information from a disc record having a spiral information track by a track4ollowing stylus when stylus/record relative velocity is established; wherein normal operation of said system involves sensing of said prerecorded information including track identification information along successive convolutions of said spiral track in a regular progression toward one extremity, and wherein the system is programmed for play by play operating commands; a stylus translating apparatus comprising: a carriage subject to translatory motion in correlation with radial motion of said track-following stylus during playback; a stylus arm carrying said track-following stylus at one end thereof; means foryieldably securing the other end of said stylus arm to said carriage; said yieldable securing means permitting said track-following stylus to engage the disc record during a playback; a permanent magnet secured to said stylus arm; a pair of spaced coils having non-magnetic cores for selectably providing a magnetic field therebetween; means for mounting said pair of coils to said carriage such that said permanent magnet is disposed therebetween; programmable means responsive to a control signal for generating a drive signal to energize said coils wherein the characteristics of said drive signal are determined by said control signal;; control circuitry responsive to player operating commands and to the track identification signals for selectively generating control signals, thereby selectively producing drive signals to the pair of coils and imparting stylus translation, said control circuitry calculating the stylus translation produced as the result of a particular control signal and altering said control signal in such manner as to more nearly produce a stylus translation in accordance with an operating command.
8. The apparatus as set forth in Claim 1, wherein said control circuitry is also responsive to sector identification signals for generating said control signals for discreet sectors of the disc record, said control circuitry calculating the error between actual kicker induced stylus translations and programmed stylus translations and adjusting said control signals to reduce said error.
9. The apparatus as set forth in claim 8 wherein the control circuitry includes a means to alter the control signals for the remaining sectors in accordance with a correlation function, when the control signal for a particular sector is calibrated.
10. The apparatus as set forth in Claim 9, wherein the correlation function is proportional to 1 + E Cos H or 1 +W cos (2H) where, E is a coefficient related to disc track eccentricity, W is a coefficient related to disc warpage and H is the angular displacement of a disc sector relative to an arbitrary reference sector.
11. The apparatus as set forth in claim 8 wherein the control circuitry comprises: signal recognition circuitry responsive to said disc track and sector identification signals for producing a substantially digital signal representation thereof; a microprocessor responsive to player program commands for energizing the kicker means to produce stylus translations and to adjust the kicker drive signals from a resultant evaluation of said digital signals.
12. Apparatus as set forth in any of Claims 1-11 and substantially as described with reference to any one or more of the drawings.
GB8033020A 1979-10-18 1980-10-13 Adaptive stylus translator Expired GB2060950B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US8624679A 1979-10-18 1979-10-18
US06/086,245 US4330879A (en) 1979-10-18 1979-10-18 Adaptive stylus kicker using disc track and disc sector information

Publications (2)

Publication Number Publication Date
GB2060950A true GB2060950A (en) 1981-05-07
GB2060950B GB2060950B (en) 1984-03-07

Family

ID=26774518

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8033020A Expired GB2060950B (en) 1979-10-18 1980-10-13 Adaptive stylus translator

Country Status (10)

Country Link
AT (1) AT376511B (en)
AU (1) AU538156B2 (en)
DE (1) DE3039260C2 (en)
ES (1) ES8201792A1 (en)
FI (1) FI803216L (en)
FR (1) FR2468180A1 (en)
GB (1) GB2060950B (en)
IT (1) IT1133648B (en)
NL (1) NL8005746A (en)
PL (1) PL134777B1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2488023A1 (en) * 1980-07-31 1982-02-05 Rca Corp PROCESSOR-CONTROLLED VIDEODISK RESTITUTION DEVICE
FR2494069A1 (en) * 1980-11-10 1982-05-14 Rca Corp DEVICE FOR ADVANCING A TRANSDUCER FOR READING A VIDEODISK ABOVE A DEFECT IN THE DISK
EP0139332A2 (en) * 1983-10-17 1985-05-02 Koninklijke Philips Electronics N.V. Apparatus for reproducing information from a disc-shaped optically readable record carrier

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5817667U (en) * 1981-07-28 1983-02-03 日本ビクター株式会社 Disc-shaped information recording medium reproducing device

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2118657C3 (en) * 1971-04-17 1979-08-30 Ted Bildplatten Ag Aeg-Telefunkenteldec, Zug (Schweiz) Playback apparatus for a hat with information stored in a spiral groove, the drive functions of which are controlled by control information provided on the disk, and disk therefor
JPS5048820A (en) * 1973-04-11 1975-05-01
US3963861A (en) * 1974-11-12 1976-06-15 Rca Corporation Disc record groove skipper apparatus
GB1519974A (en) * 1974-08-22 1978-08-02 Rca Corp Disc record groove skipper apparatus
US4000510A (en) * 1975-06-02 1976-12-28 Ampex Corporation System for storage and retrieval of video information on a cyclical storage device
GB1577133A (en) * 1976-03-19 1980-10-22 Rca Corp Video information record and playback apparatus
DE2850363C2 (en) * 1977-11-22 1986-04-17 Victor Company Of Japan, Ltd., Yokohama, Kanagawa Random access arrangement for an apparatus for reproducing information from a rotating recording medium
AU530389B2 (en) * 1978-05-22 1983-07-14 Rca Corp. Recording/playback apparatus facilitating track skipping

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2488023A1 (en) * 1980-07-31 1982-02-05 Rca Corp PROCESSOR-CONTROLLED VIDEODISK RESTITUTION DEVICE
FR2494069A1 (en) * 1980-11-10 1982-05-14 Rca Corp DEVICE FOR ADVANCING A TRANSDUCER FOR READING A VIDEODISK ABOVE A DEFECT IN THE DISK
EP0139332A2 (en) * 1983-10-17 1985-05-02 Koninklijke Philips Electronics N.V. Apparatus for reproducing information from a disc-shaped optically readable record carrier
EP0139332A3 (en) * 1983-10-17 1985-06-12 N.V. Philips' Gloeilampenfabrieken Apparatus for reproducing information from a disc-shaped optically readable record carrier

Also Published As

Publication number Publication date
IT8025061A0 (en) 1980-10-01
DE3039260A1 (en) 1981-05-07
FR2468180A1 (en) 1981-04-30
ATA514280A (en) 1984-04-15
AT376511B (en) 1984-11-26
NL8005746A (en) 1981-04-22
ES496029A0 (en) 1981-11-16
GB2060950B (en) 1984-03-07
FI803216L (en) 1981-04-19
AU6316980A (en) 1981-04-30
AU538156B2 (en) 1984-08-02
PL134777B1 (en) 1985-09-30
DE3039260C2 (en) 1985-01-24
PL227354A1 (en) 1981-06-19
ES8201792A1 (en) 1981-11-16
IT1133648B (en) 1986-07-09

Similar Documents

Publication Publication Date Title
US5936787A (en) Method and apparatus for reducing vibration on a disk spindle motor by detecting the vibrations and correcting the motor driving signal according to the detected vibration
US5610776A (en) Method of optimizing read channel of disk drive recording apparatus by using error rate
GB2060940A (en) Device for measuring the speed of a movable system with respect to a data carrier
US5585974A (en) Disk drive with PRML read channel calibration using a noise generator
US4330879A (en) Adaptive stylus kicker using disc track and disc sector information
EP0720164B1 (en) Controlling apparatus and method of controlling tracking for tape-shaped recording medium
US6519106B1 (en) Method and apparatus for correcting digital asymmetric read signals
GB2060950A (en) Adaptive stylus translator
US4340949A (en) Processor controlled video disc servo system
US4412319A (en) Video disc player with self calibrating stylus translator
US4451859A (en) Magnetic video head position control
JP2818287B2 (en) Track following control method for magnetic tape recorder
CA1145466A (en) Adaptive kicker stylus
US4912572A (en) Magnetic disk drive with effective AGC control of servo signals by selectively varying A/D converter reference level
US5202801A (en) Integrated circuit for producing sensor detection signals in a recording/reproducing apparatus
US5255126A (en) AGC circuit with constant envelope circuit for reproduced RF signals from plural channels
JPH0836811A (en) Tracking controller
KR920009099B1 (en) Tacho pulse generating circuit
EP0462634B1 (en) Apparatus and method for controlling an audio playback signal at variable tape speed
KR0170258B1 (en) Capstan motor control method of vcr
US4471476A (en) Pickup arm drive device
US4685006A (en) Magnetic recording-reproducing device
KR940001070Y1 (en) Recording position decision circuit for recording device
JP2604966B2 (en) Equal error rate recording method and device
JP2924391B2 (en) Magnetic recording / reproducing device

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee