FR2461325A1 - SYSTEM FOR RECORDING PRE-RECORDED SIGNALS ON A DISK WITH NEEDLE POSITION DETECTION DEVICE - Google Patents

Abstract

THE INVENTION RELATES TO A SYSTEM FOR RETURNING PRE-RECORDED SIGNALS ON A DISK WHERE INFORMATION IS RECORDED ALONG A SPIRAL BEACH ARRANGED ON ITS SURFACE BY MEANS OF A DEVICE FOLLOWING THE BEACH. ACCORDING TO THE INVENTION, A TROLLEY IS SUBJECTED TO A TRANSLATION ALONG A PATH RADIALLY ARRANGED TO THE DISK; A FLEXIBLE MEANS ATTACHES THE DEVICE TO THE TROLLEY; A FIRST MEANS INCLUDES A CAPACITY 92 INDICATING THE POSITION OF THE DEVICE WHICH IS DEFINED BETWEEN A FIRST ELECTRODE 94 IN FIXED RELATIONSHIP WITH THE DEVICE AND A SECOND ELECTRODE 96 MOUNTED ON THE CART ADJACENT TO THE FIRST ELECTRODE; AND A SECOND MEDIUM 76, 108, 110, 112, 114, 116 IS CONNECTED TO THE FIRST ELECTRODE TO DETECT VARIATIONS IN THE CAPACITY INDICTING THE POSITION OF THE DEVICE IN ORDER TO PRODUCE A SIGNAL INDICTING THE RELATIVE POSITION OF THE DEVICE AND THE TROLLEY ALONG THE PATH. THE INVENTION APPLIES IN PARTICULAR TO THE RESTITUTION OF VIDEODISKS.

Description

The present invention relates to a device for detecting the

  relative position of a needle along a track or range relative to an independently driven arm carriage, for use in a videodisc. In a certain registration system of

  high density information, signals are recorded

  in the form of geometrical variations at the bottom of a smooth spiral groove on a disk, the surface of which consists of a conductive covered material

  a thin coating of a dielectric material.

  The turntable has an arm carrying a needle engaging the groove at its free end, and the other end is fixed by an elastic coupler or flexible to a carriage. A platinum is provided

  to rotatably support the disc during playback.

  The carriage is subjected to a translation, independent of the lateral movement of the needle engaging the groove, along a path arranged radially to the disk during the restitution. Reading circuitry is used to detect variations in signal representative capacitance between an electrode incorporated in the reading needle and the conductive material of the disc while the latter is being driven.

  in rotation to restore pre-recorded signals.

  U.S. Patent No. 3,842,194 to Clemens discloses

  a sensor or reader system with the capacity of the type

above described.

  In a high density information recording system, it is desirable to house the needle assembly in a protective cartridge of the type described in US Patent 4,030,124 (Allen). In the arrangement disclosed in Allen's patent, the other end of the needle arm is attached to the housing

  cartridge by an elastic coupler ousouple.

  A conducting spring with a blade is interposed between the elec-

  trode of the needle and a terminal arranged on the cartridge. The reading cartridge is received in a compartment provided in the carriage of the arm can have a translational movement. An electrical contact is established between the terminal of the cartridge and the read circuits while the cartridge is contained in the carriage compartment. The leaf spring of the needle is described in more detail

  in US Pat. No. 4,070,50 (Dholakia).

  In the restitution of disks with high densities of the furrow (ie in the order of 3543 to 3937 turns per centimeter), conditions are occasionally encountered where the presence of some form of discontinuity in the groove of the disk forces Needle to read turns of the groove rather than follow the successive turns of the spiral groove in a continuous progression. Depending on the nature of the defect, a meeting of the needle and defect may result in a deflection of the reading needle inward (i.e., leap forward) or its deviation to outside (ie jump backwards). In some cases, the deviation of the needle outwards is repeated a number of times, forcing the needle to follow again one or more turns already traversed, and thus producing a repeated reading - with annoying effects on the

  image viewing and sound reproduction.

  Such a repeated crossing of despires is called

hereinafter "blocked path".

  In systems of the above type, it is desirable to provide for the correction of problems relating to the blocked groove, for example by causing the reading needle to move inwardly during the presence of a blocked groove for relocate the needle to a point along the continuation of the spiral groove beyond the particular defect

  causing jumps backwards.

  The device used to relocate the needle from one turn of the groove to another, in addition to its use for the blocked groove correction function, is also adapted to provide features such as fast forward / slow motion, motion

  reverse fast / slow, a repetition and a search.

  In U.S. Patent Application No. 039358 filed May 15, 1979 in the name of Simshauser is described an example

  a jumper device beach or track.

  Effective operation of beach or track jumpers of the type described above requires that a fixed relationship in space be maintained

  between the reading needle and the arm carriage.

  For this purpose, a system for detecting the relative position of the needle relative to the carriage of the arm is described. The disclosed system includes a capacity indicative of the position of the reading needle which is formed between a first electrode attached to the needle and a second electrode mounted on the carriage near the first electrode. The turntable signal reading circuitry also serves to detect capacitance variations indicating the position of the needle to produce a representative signal

  the relative position of the needle.

  The translation of the carriage can be modified in response to the signal representative of the position of the needle so as to maintain an advantageous relationship

  in the space between the needle arm and the carriage.

  Examples of dimensions include the following: (1) movable electrode mounted on the needle: 0.127 X 1.9_5nm, (2) stationary electrode mounted on the carriage: 0.508 × 2.54 mm and (3) lateral gap between the

electrodes: 0.0762 mm.

  According to one aspect of the present invention, the flying conductor of the needle serves as a more mobile electrode of the capacity indicating the position.

of the needle.

  On-site adjustments of the space between the first electrode mounted on the needle and the second electrode mounted on the carriage may become necessary following the installation of the cartridge in the carriage compartment, due to the fineness of the dimensions involved. According to another characteristic of the invention, the second electrode is fixed in the casing of the cartridge. The space between the flying conductor and the electrode mounted on the cartridge in the device can be adjusted at the factory, thereby substantially avoiding the

  need for other flat adjustments.

  The invention will be better understood and other purposes, features,. details and benefits of it

  will become clearer during the description

  explanatory text which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating an embodiment of the invention and

wherein: -

  FIG. 1 is a diagrammatic representation of a capacitive-type videodisc-turning device in which the device for detecting the position of the needle is incorporated; FIG. 2 diagrammatically illustrates the principles of the capacitive type of a signal reading system; Fig. 3 is a perspective view of a read cartridge for use with the needle position detecting device of Fig. 1, with the cartridge illustrated returned from below to expose its features; FIG. 4 shows a perspective view of a part of the returned cartridge of FIG. 3, partly broken away to illustrate its details; FIG. 5 shows in the form of a block diagram, the electronic device of the turntable is incorporated; a circuit for the device for detecting the position of the needle of FIG. 1; FIGS. 6 and 7 illustrate circuit diagrams for carrying out various functions of the system for detecting the position of the needle of the figure; and FIG. 8 to 10 show a device for detecting the position of the needle according to the present invention, corresponding FIGS. 8 to 10

  respectively in Figures 1, 3 and 4.

  Figure 1 schematically illustrates a videodisc rotator 10 having a plate 12 for rotatably supporting a disk 14.Amotor drives the plate so that it rotates at the right speed. U.S. Patent No. 3,912,283 to Hammond et al., Discloses

  an example of a platinum drive system.

  Video signals are recorded, as schematically shown in FIG. 2, in the form of corrugations of a smooth spiral groove 16 disposed

  on the disc, and whose surface consists of a coating

  Thinning of a dielectric material 18 covering a conductive material 19. In a reading needle is incorporated a conductive electrode 22 which forms a representative capacity of the signal with the conductive material of the disc when the needle is lowered on the disc for a restitution . The representative capacity of the signal varies according to the signals

  recorded on the disc while a movement is

  relative needle / disk. In the turntable are used reading circuits sensitive to variations in the representative capacity of the signal

  to reconstruct the recorded signals.

  The reading needle 20 is fixed to the free end of an arm 24 by means of a needle holder

  26 as shown in Figures 3 and 4.

  The other end of the arm 24 is fixed to a connecting plate 28 by means of an elastic or flexible coupler 30. The connection plate is suspended in a reading cartridge 32 by means of a flexible membrane 34. A spring 36 U-shaped is used to hold the delicate set of the needle in the confines of the body of the cartridge during its storage and its

  handling. A conductive leaf spring 38 (i.e.

  say flying conductor) connects the read electrode 22 to a terminal 40 on the body of the cartridge. An extension 42 is disposed on the needle port for

  prevent needle excursions from one side to the other.

  The turntable comprises a carriage 44 of the arm which is translationally moved along a path arranged on the disc 14 on the plate 12. As shown diagrammatically in FIG. 1, a DC motor and variable speed 46 causes the carriage to translate at an appropriate speed in the manner to be described subsequently. The carriage 44 is provided with a compartment 48 for detachably receiving the cartridge 32. The introduction of the cartridge into the compartment of the carriage establishes an electrical contact between the terminal 40 of

  the cartridge and a terminal 50 of a read circuit 52.

  In the carriage is mounted an arm expander device 54. When the cartridge is installed in the trolley and the cover 56 of the trolley is closed, a mechanism 58, sensitive to the movement of the cover,

  push the arm expander towards the cartridge for

  kill the mechanical engagement between the connection plate 28 of the cartridge and a support disposed on the expander

  of arms, which can have a translation movement.

  The arm expander 54 imparts translational movement to the needle in a manner opposed to

  cyclic deviations of the relative speed needle / dis-

  only during the restitution. The cyclic deviations of the relative velocity of the needle / disk result from a number of sources, for example eccentricity,

  warping and others. In US Patent No. 3,983,318.

  (Miller) is described an example of an expander device

of arms.

  In the trolley is also arranged a device

  60 to raise and lower the needle arm.

  The device 60 serves (1) to gently lower the playback needle on the disc for playback, (2) to raise the needle off the disc in record player pause mode, and (3) to raise the disc needle to allow it to move away from the bead of the disc while the carriage moves from a rest position away from the

  disc to a playback position on the disc.

  When the cover 56 is closed, a tab is disposed thereinnule the action of the spring 36 for retaining the arm of the needle, allowing the arm 24 to rest on a support member 62 of the device for raising and lowering. the carriage has an opening 64 through which the reading needle is lowered for restitution. We can refer to

  U.S. Patent No. 4,053,161 (Bleazey) for a description

  more detailed device for raising and lowering the needle. The Simshauser beach jumper or track device (US Patent Application No. 039358) comprises a small permanent light magnet 66 attached to the rear side of the extension 42 and two large diameter, air core coils 68 and 70. arranged around dampers

  plastics 72 and 74 mounted in the carriage.

  Note that the dampers 72 and 74 limit the excursions of the extension 42 disposed on the arm of the needle from one side to the other. The coils of the jumper of turns or beach are connected so that during an excitation, theyproduce auxiliary magnetic fields. The permanent magnet is dimensioned so that its north pole is interposed between the

  coils when the needle is lowered for a restitution

  tion. The arm of the needle is moved inward or outward according to the polarity of the actuation pulse applied to the coils. As previously indicated, the beach jumper performs a multitude of functions, such as removing a blocked groove, special effects,

active and other research.

  Figure 5 is a block diagram of an electronic circuit of the turntable containing a mounting for the needle position detecting device. The editing used to render the recorded signals on the disc. will be explained first. As can be seen in FIG. 5, the terminal 50 of the reading circuit 52 is connected to the conductive electrode 22 of the needle. The read circuit, responsive to variations in the capacitance 53 representative of the signal formed between the reading electrode 22 and the conductive material of the disc 14, produces at the output terminal 76 audio and video signals recorded on the disc. Reference can be made to US Pat. No. 3,872,240 to Carlson et al. And No. 4,080,625 to Kawamoto et al.

  descriptions of examples of reading circuits.

  The output signal of the read circuit 52 is applied to two band-pass filters 78 and 80. The band-pass filter 78 of the image carrier has a relatively wide bandwidth containing the deflection range of the high-frequency image carrier ( that is 4.3 to 6.3 MHz) as well as the required regions of adjacent sidebands, and selectively allow the image carrier component of the recorded signal to be excluded to the relative exclusion of the carrier component The carrier bandpass filter 80 has a relatively narrow bandwidth containing the low frequency carrier (i.e., 716 kHz 55 KHZ) deflection range as well as the adjacent adjacent sideband regions, and it selectively allows the sound carrier component of the recorded signal to be switched to the relative exclusion

image carrier sacomposer.

  The output signals of the respective bandpass filters 78 and 80 are applied to respective demodulators 82 and 84. The image demodulator 82 produces, at its output terminal, the image signal information containing the synchronization components. and the sound demodulator 84 produces, at its output terminal,

the audio signal information.

  An image signal processing device 86 connected to the image demodulator performs the separation of the chrominance information and the luminance information. A composite video signal generator 88 recombines the chrominance and luminance information according to, for example, the NTSC format. A transmitter circuit processes the sound, luminance and chrominance information to form a signal suitable for application to a conventional TV in color where color images can be developed according to the recorded information. In U.S. Patent No. 4,097,899 in the name of JP Yu is described

  an example of a transmitter circuit.

  The electronic circuits of the turntable also contain circuits connected to the output of the signal reader for detecting the presence of grooves blocked on the disc. An example of a blocked groove detection scheme is described in the patent application

  US 908,516 filed May 22, 1978 in the name of Palmer.

  The blocked groove correction signal is applied to the coils 68 and 70 to effect a suppression of the

furrow blocked.

  The needle position detecting device includes a capacitance 92 indicating the position of the needle established between a first electrode 94 held in fixed relation on the arm of the needle 24 and electrically connected to the flying conductor 38, and a second electrode 96 connected to a terminal 98 disposed on the carriage 44 of the arm near the first electrode as can be seen in FIG. 5. By way of example, the first electrode has 0.127 mm on

  1.905 mm and the second electrode is 0.508 mm by 2.54 mm.

  The capacity 92 indicating the position of the needle is arranged in series with a varactor diode 100. The varactor diode is connected to the output terminal 104 of a reference oscillator 102 at 260 kHz by means of a resistor 106. capacity 92 indicating the position of the needle is modulated by the space between the needle and the carriage 44, and the capacity of the varactor diode

  is modulated by the reference oscillator 102.

  Figure 6 shows a circuit diagram adapted to the production of the 260 kHz reference carrier, and the values of the various elements shown therein will be given below in a table. The read circuit 52 further serves to detect variations in the capacity formed by the capacitance 92 indicating the position of the needle and the capacitance of the varactor diode 100 in series. These variations appear at the output terminal 76 in the form of a 260 kHz signal whose amplitude varies inversely with the space between the position detection electrodes 94 and 96. This signal is separated from the remainder of the signals appearing in FIG. the output terminal 76 of the read circuit by a bandpass filter 108 connected thereto. The bandpass filter has a bandwidth containing the required deflection range of the 260 kHz reference carrier. The signals separated at 260 kHz are amplified by an amplifier 110. A peak detector 112 connected to the amplifier 110 produces, at its output, a signal which represents the relative position of the read pointer 20 relative to the carriage 44. of the arm. The signal at the output of the peak detector is applied to a drive amplifier 114 which produces at its output terminal 116 an error correction signal which can be applied to the motor 46, which drives the carriage. The amplitude of the signal applied to the motor of the carriage is such that the space between the needle and the carriage is maintained at a predetermined optimum level. A circuit diagram for performing the above functions is illustrated on

  Figure 7, and the values of the various elements therein.

  are shown are also given in the attached table. As previously indicated, it is desirable to eliminate adjustments in the detection capability of

  the position of the needle on the spot. The capacity represented

  The need for a needle position according to the invention not only makes field adjustments unnecessary, but also eliminates the need for a separate electrode mounted on the needle. A device according to the invention will now be described with reference to FIGS. 8 to 10 which correspond to FIGS. 1, 3 and 4 previously described. As can be seen in FIG. 10, an electrode 120 of the device according to FIG.

  the invention is fixedly arranged on the cartridge 32.

  A wire 122, passing through an opening 124 in the wall of the cartridge casing, electrically connects the electrode 120 mounted on the cartridge to a terminal 126 provided on the casing of the cartridge in the manner indicated in FIGS. 9 and 10. terminal 126 of the cartridge comes into electrical engagement with the terminal 98 when receiving the cartridge in the compartment

  of the carriage as shown in Figure 8.

  According to one aspect of the invention, the flying conductor 38 of the needle, which serves to form the electrical connection between the electrode-22 of the reading needle and the readout circuit 52 of the turntable, serves more second electrode of the capacity representative of the position of the needle according to the invention, when the arm of the needle is lowered on the disk for

a restitution.

  Note that although the needle position sensing device according to the invention is used to vary the shape of the translation of the carriage of the arm so as to maintain a desired space between the reading needle and the cart, it is also suitable for other purposes, such as detecting grooves blocked on the disc. Moreover, it is important to understand that while the

  this description was made in the context of

  grooved discs, it also applies to flat discs. Various defects on flat disks may

  force the read pointer to travel the same range.

  The present system can be advantageously employed for

  delete these cases when restoring flat disks.

TABLE OF VALUES

  By way of example, the values of the various elements used in FIGS. 5-7 are given:

I. CAPACITORS:

  (1) C1 - 0.01 microfarad (2) C2 - 1-000 picofarads (3) C3 - 1.0 microfarad (4) C4 - 220 picofarads (5) C5 - 0.01 microfarad (6) C6 - 2, 2 microfarads (7) C7 - 10.0 microfarads

II. RESISTANCE:

  (1) R1 - 10.0 kilohms (2) R2 - 10.0 kilohms (3) R3 - 7.5 kilohms (4) R4 100.0 kilohms (5) R5 - 13.0 kilohms (6) R6 - 4, 7 k: ilohms (7) R7 - 3.0 kilohms (8) R8 - 39.0 kilohms (9) R9 - 2.0 kilohms (10) R10 - 4.3 kJ (11) R11 - 82.0 c ( 12) R12 - 4.7 ki (13) R13-10.0 o

(14) R14-10.0 I

(15) R15 - 62.0 c

(16) R16 - 510.0

  (17) R17 - 7.5 ki (18) R18 - 1.0 kd (19) R19 - 5.0 ki

(20) R20 - 10.0

III. DIODES:

(1) VD1 - 147794C

(2) D2-3 - IN60

(3) D4-5 - IN914

  ilohms ohms ilohms ilohms kilohms hms ohms ilohms ilohms ilohms: ilohms) - 1

IV. TRANSISTORS:

(1) Q1 - 1417330-3

(2) Q2-5 - MPSA17

(3) Q6 - MPSU05

V. MISCELLANEOUS

  (1) CF1 - 260 kHz. Ceramic resonator (2) CF2 - 260 kHz. Ceramic Filter Naturally, the invention is not limited to the embodiment described and shown which has been given by way of example only. In particular, it includes all the means constituting technical equivalents of the means described and their combinations if they are executed according to its spirit and implemented

  as part of the protection as claimed.

Claims (7)

R E V E N D I C A T I 0 N S   A system for reproducing pre-recorded signals on a disc where information is recorded along a spiral track disposed on its surface, by means of a device according to the range, characterized by a carriage (44) subject to a translation along a path disposed radially to said disk (14); flexible means (30) for securing said device to said carriage; first means having a capacitance (92) indicative of a position of the device defined by a first electrode (94) held in fixed relation to said device and a second electrode (96) mounted on said carriage adjacent to said first electrode; and second means (76, 108, 110, 112, 114, 116) connected to said first electrode for detecting capacitance variations indicating the position of the device to produce a signal indicative of the relative position of said device relative to said car along said path. 2. System according to claim 1, characterized in that the first aforementioned means further comprises a means connected to the second electrode (96) above and modulated at a given frequency and in that said modulated means comprises a varactor diode (100) connected in series   with a source (102) of oscillations at the given frequency.   3. System according to claim 1 of the type comprising a reading circuit connected to an electrode incorporated in the needle for detecting variations in a capacitance representative of a signal formed by said reading electrode and a conductive material disposed in said disc. for outputting the pre-recorded signals to the output terminal, characterized in that the device of said first means is a needle (20), the first electrode (94) being attached to said needle and connected to the read circuit (52); in that the first   means furthermore comprises means connected to the second electro-   of (96) and is modulated at a given frequency; and second means (78, 82, 86, 88, 90) connected to the output terminal (76) of the read circuit for outputting signals at the given frequency to the relative exclusion of the pre-recorded signals to produce the signal indicating the relative position of the needle relative to the cart along the path.   4. System according to claim 3, characterized in that said modulated means comprises a varactor diode (100) connected in series with a source (102).   of oscillations at the given frequency.   5. System according to any one of the claims   preceding, characterized by signal responsive means indicative of the variation for varying the translational speed of the carriage (44) so as to maintain a desired lateral gap between the device and carriage.   6. System for reproducing pre-recorded signals on a disk where information is recorded along a spiral range disposed on its surface, by means of a needle along the range where a reading electrode is incorporated, said system having a carriage translated along a path radially disposed on said disk; flexible means for attaching said needle to said carriage; means for detecting a capacitance indicative of a signal formed between the reading electrode and said disc for producing the pre-recorded signals at the output; a flying conductor for connecting said reading electrode to said capacitance detecting means; characterized by a capacitance (92) indicating the position of the needle defined by a first electrode (94) attached to said needle and a second electrode (96) mounted on said carriage adjacent to said first electrode; said signal capacitance detecting means (52) also for detecting the capacitance indicating the position of the pointer to produce signals indicative of the position of the pointer at its output terminal; said flying conductor (38) further serving as a first electrode   said capacity indicating the position of the needle.   7. System according to claim 6, of the type further comprising a cartridge for housing the aforementioned needle the aforementioned carriage having a compartment for detachably receiving said cartridge; said flexible means holding said needle to said carriage, said flying conductor having an end attached to said reading electrode, its other end being attached to a first terminal disposed on said cartridge; said first terminal engaging a terminal disposed in said carriage for connecting said reading electrode to said capacitance detecting means, said cartridge being received in said carriage compartment; characterized in that the second electrode (96) comprises a member fixedly mounted on the cartridge (32) so that said member is well-arranged during the restitution with respect to said flying conductor (38); said cartridge (32) further comprising a second terminal (40) in contact with said element and subjected to engagement with another terminal (50) disposed in said carriage (44) while said cartridge   is contained in the trolley compartment.