KR840001861B1 - Video disc player - Google Patents

Abstract

A video disc player derives video signals from successive tracks that form a continuous spiral on the disc using a light source and a lens system. The lens system is carried by a rotatable element at a predetermined spacing from the surface of the disc and defines a folded optical path. The optical path includes a mirror which is articulated for rotational motion about an axis, which shifts the point of impingement of the transmitted light beam onto the disc in a radial direction.

Description

Video disc player

1 is a general block diagram of a video disc player.

FIG. 2A is a schematic diagram of the optical system shown in FIG.

FIG. 2B is an enlarged view of the information recording surface of the video disk shown in FIG.

3 is a schematic partial side view of a video disc player according to another example of the present invention.

4 is a schematic partial side view of a read head.

5 is a schematic representation of a radial tracking system.

6A is a schematic diagram of a spindle servo substem.

6b is a schematic representation of a tangential servo subsystem.

Figure 6c is a schematic of the carriage servo subsystem.

FIG. 7 is a perspective view of a cam and cam follower device for focusing a read beam on an information track on the video disc shown in FIG.

FIG. 8 is an enlarged side view of the optical head and air bearing apparatus used in the video disc player shown in FIG.

9 is a detailed view of the signal reproducing circuit and the mirror control circuit shown in FIG.

FIG. 10 is a schematic diagram illustrating a pair of mirrors formed on a converging surface used for the video disc player shown in FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to reading frequency modulated video signals accumulated on a plurality of information reflection elements and non-reflection elements continuously on a plurality of information transistors formed on a video disc, and particularly, to direct the read line velocity to collide with the information track. (Iii) a video disc player composed of an optical system capable of collecting signals reflected and modulated by light reflecting elements and non-reflecting elements of an information track.

A frequency modulated electrical signal is reproduced from the modulated optical signal and sent to a signal processing portion for application to a standard television receiver or monitor. A signal reproduced from the modulated optical signal is sent to a plurality of servo systems to generate a control signal. The control signal is used to adjust the focused light beam at the same time as the lens is adjusted to the proper focus on the information recording surface of the video disc. By keeping it in place, the focused light spots strike the center of the information track.

Accordingly, the present invention is directed to a video disc player which reproduces a frequency modulated video signal from an information recording surface of a video disc, wherein frequency modulated video information is accumulated on a plurality of concentric circles or single spirals formed in the information recording portion on the surface of the video disc. The frequency-modulated video signal is represented by display elements arranged in a track shape on the information recording surface portion of the video disc. The display element means that the light reflection element and the non-reflection element are arranged in a row on the information track.

A laser is used as a source of light beams, and an optical system is used to focus the light beams to have a diameter almost equal to the width of the information display element located on the information track. A microscope objective is used to adjust the reading flux to one point, and also to condense the flux reflected at the point of impact with successively arranged light and nonreflective elements.

The output of the microscope lens is applied to the signal regeneration system so that the reflected line flux is used primarily as an information element, and at the same time, it is used as a control signal source for generating a radial tracking error signal and a connection error signal. . The information portion of the recovered frequency modulated video signal is sent to the frequency modulation processing system so as to be operated before being transmitted to a standard TV receiver or TV monitor.

The control part of the reproduced frequency modulated video signal is applied to a number of servo systems to control the position of the reading flux with respect to the center of the information track, and to maximize the concentration of reflected light when the lens is positioned at the optimum focus position. The position of the lens is controlled as much as possible. The tangential servo subsystem is used to control the time-base error introduced in the reading process due to the mechanical operation of the reading system. This time axis error appears as a phase error in the reproduced frequency modulated video signal. By applying the phase error to the mirror moving tangentially, it adjusts the position where the focused light spot impinges on the information track. The tangential mirror moves the light spot along the information track in the front-rear direction to correct for the detected phase error. Broadly interpreted, the tangential mirror is a device used to correct the time axis error by adjusting the time axis for the signal read from the video disc.

The radial tracking servo system is used to keep track of the point of focus on the information track in the radial direction. The radial tracking servo system responds to the control portion of the reproduced frequency modulated signal from the center of the track position. An error signal is generated that indicates a residual offset to the position. This tracking error is used to control the movement of the radial tracking mirror so that the light spot returns to the center of the track position.

The carriage servo system uses a closed loop operation to move the carriage as directed by the current generator. This carriage servo system modifies the approximate radial tracking of the information track by controlling the relative movement of the video disk and the read line speed at a constant rate. The current generator is a device that supplies a continuous bias current so that the carriage device moves in a constant direction at a predetermined speed.

The carriage tachometer current generator is mechanically connected to the carriage motor to generate a current representing the instantaneous speed of the carriage motor. The current coming from the carriage tachometer is compared with the current generated from the current source of the addition circuit. The addition circuit detects the difference between the current generated by the current generator and the current generated by the carriage tachometer, and applies an error signal to the power amplifier to move the cage device under the control of the current generator.

The spindle servo circuit rotates the spindle and the video disk mounted on the spindle at a constant speed. The feedback loop ensures that the rotational speed does not deviate from a very accurate reference frequency.

In an embodiment of the present invention, a movable mirror, which is an articulated mirror, is used together with another mirror to provide a plurality of reflection paths. The mirror may be moved slightly in order to move the collision point of the light spot on the disc by reflecting the reading flux from the highly concentrated laser light source several times. Moreover, the greater the reflection, the longer the optical path, allowing the use of long focal length lenses to direct light spots to the video disk and to focus the image of the reflected light on the photosensitive element.

In addition, another feature of the present invention is that the irradiated light can be directed to a specific point and conveyed information from the illuminated light point to the detection device. That is, as one example, photosensitive pickup is used as one input of the differential amplifier and a fixed bias supply is used for the other input. The bias is adjusted to balance the pick up input when the pick up is illuminated by the light spot reflected at the periphery of the track, i.e. in the middle of the information track. When the intensity of radiation from the detector increases in systems where the track is darker than the band between the tracks, a servo signal is generated to drive the mirror in the first direction so that the light spot moves toward the track and its center. . Similarly, when the radiation decreases, the bias becomes relatively large, so that an error signal is generated and the mirror and the light point are moved in opposite directions, respectively, in the direction toward the periphery of the track.

Another Confucian mirror, a movable mirror, may be installed to rotate in a direction orthogonal to the radial tracking direction.

This tracking takes place in the tangential or circumferential direction and makes it possible to eliminate time-base errors resulting from differences in timing and synchronization of recorded information with respect to timing frequencies generated in the reproduction circuits. As is known, TV circuits, especially color TV circuits, require extremely accurate time synchronization to maintain color fidelity and to correct horizontal equality. Therefore, the error interposed in synchronization between the timing information recorded on the video disk and the local oscillator of the playback apparatus can be eliminated by moving the mirror in the tangential direction or the orthogonal direction.

In another improved example, the bias force required to maintain an air bearing supporting an objective lens at a distance from the surface of the video disk is varied as a function of the surface speed of the video disk. Since the relative radial position of the air bearing and the surface velocity are directly related, a simple mechanical cam device is used to modify the bias force acting on the air bearing as a function of the radial position of the regeneration device.

Accordingly, it is an object of the present invention to improve a video disc player apparatus and method for optically adjusting the read-out irradiated to a video disc on which video information is recorded by using a pair of movable mirrors and fixed mirrors.

Another object is to provide a video disk apparatus for reading information recorded in an information track formed on a surface member of a video disk. Such a video disc player device is composed of a light source for generating a reading flux and a beam directing system for propagating the reading flux generated from the light source along the flux path to the forward track. In the track, display elements (i.e., light reflecting elements and non-reflecting elements) are provided. Element) modulates the read line flux and reflects the read line flux back through the portion of the read path. The signal regeneration and detection circuit receives the reflected flux.

It is an object of the present invention to improve a tracking circuit and method for optically scanning a video disk in a folded beam path, and information accumulated on the video disk by using the optical paths of the incident beam and the reflected beam in common. It is also an object of the present invention to improve an injection apparatus and method capable of regenerating the same.

In addition, by providing a mirror apparatus and method capable of performing coarse or fine radial movement control to the video reading device in the optical path between the surface of the video disk and the light source, and by configuring the movable mirror device in the optical path, It is also an object of the present invention to allow the position of the transfer point of radiant energy on the surface of the disc to be varied widely even at the smallest, and at the same time to transfer the returned radiant energy to the detector system.

It is also an object of the present invention to provide a video disc player which irradiates a read line flux on the surface of the disc and irradiates the reflected line flux from the photosensitive detector for detecting the radiation coming back from the video disc.

It is also an object of the present invention to provide an apparatus and method that allow the video disk to continuously maintain the focus of the light beam irradiated onto the information track of the video disk as it rotates with respect to the reading device.

It is still another object of the present invention to configure a fluid bearing regulator to adjust the variable bias force applied to the readhead in a direction perpendicular to the video disc so that the distance between the readhead and the disc is constant so that it is independent of the radial position of the head. Information provided on the video disc by providing a readout device for forming and generating a differential error tracking signal that identifies the position of the readout flux relative to the center of the information track and generates a control signal for moving the readout flux toward the center of the information track. It is also an object of the present invention to provide an apparatus and method that enable effective radial tracking of tracks.

In addition, the present invention provides an apparatus and method for radially tracking an information track formed on a video disc by responding to a position of a read line flux with respect to the periphery of the information track. It is also an object of the present invention to provide a device and a method for tangentially tracking information tracks formed on a video disc by detecting.

It is also an object of the present invention to provide a video disc player including a spindle servo system capable of controlling the rotation speed of a video disc with respect to a read flux, and to move the read flux relative to an information track on the video disc. It is to provide a video disc player that includes a carriage servo system.

Objects and features of the present invention as described above will be described in detail with reference to the accompanying drawings.

The video disc player 1 shown in FIG. 1 uses an optical system 2 as an apparatus capable of optically reading information recorded on the surface of a video disc. This optical system is illustrated more specifically in FIG. 2A.

In FIG. 2a an optical system 2 is shown, which generates a readout flux 4 capable of reading an encoded signal of frequency four modulations accumulated on the video disc 5 Have 3) The reading flux 4 is polarized in a constant direction and travels toward the video disk 5 by the optical system 2. An additional function of the optical system 2 is to irradiate the image of the reading flux to the light spot 6 on the point of impact on the video disk 5.

FIG. 2B is an enlarged portion of the information recording surface 7 of the video disc 5, wherein each of the plurality of information tracks 9 has an arrangement in which a plurality of light reflecting elements 10 and non-reflective elements 11 are arranged in succession. It is indicated by a line drawn in the center. One example of antireflection is light scattering in the form as it appears when the focusing read flux 4 collides with the dish-shaped antireflection element 11 formed on the video disk 5 which is rotating on the highway. The direction of rotation of the video disk 5 under the light spot 6 in the stationary state is indicated by an arrow 12. The reading flux 4 has two moving directions, the first of which is the radial direction indicated by the arrow 13 and the second of which is the tangential direction indicated by the arrow 14. The two heads of each of the arrows 13 and 14 indicate that the light spot 6 can move to both sides in the radial and tangential directions.

The optical system 2 comprises a lens 15 which is used to ensure that the read flux 4 fills the inlet 16 of the microscope objective lens 17 sufficiently. The objective lens is used to form the light spot 6 at the point of impact of the light reflective element 10 and the non-reflective element 11 on the information track 9. Filling the inlet 16 with the reading flux 4 gives a much better result, which maximizes the luminous intensity at the light spot 6.

The reading flux 4 is passed through the beam splitting prism 20 after being properly formed in the lens 15. The axis of the prism 20 is slightly offset from the path of the reading flux 4, the reason for which will be mentioned when explaining the operation of the optical system 2 relative to the reflecting flux 4 '. do. The transmission portion of the reading flux 4 passing through the prism 20 passes through a quarterwave plate 22, which is incident light forming the reading flux 4. Impart a circular polarization. Thereafter, the reading flux 4 collides with the fixed mirror 24, which moves the reading flux 4 straight to the first movable mirror 26 and the second movable mirror 28. The function of the second movable mirror 28 is to move the beam of light in a tangential first motion with respect to the information recording surface 7 of the video disk 5, and due to the eccentricity formed during the production of the video disk 5, This is to correct the time axis error introduced into the read flux (4). The tangential direction described above is the front-rear direction along the information track 9 of the video disk 5 as indicated by the arrow 14.

The first movable mirror 26 directs the light beam to the second movable mirror 28. The first movable mirror 26 is used as a radial tracking mirror. The function of the first movable mirror 26 is to change the physical position of the reading flux 4 slightly in response to the complex tracking error signal so as to control the collision point of the reading flux 4 (i.e., the light spot 6), The reading flux is such that the information element, ie the light reflecting element 10 and the non-reflecting element 11, is radially tracked along the single information track 9.

The first movable mirror 26 moves the ship speed in the direction of the arrow 13, that is, in the radial direction, on the surface of the video disk 5. In this case, as described above, the read flux 4 is incident on the inlet 16 of the lens 17, and is focused by the lens 17 at the light spot 6 on the information track 9 of the video disk 5. .

The information track 9 is in the form of a circle or a spiral. In the following description, the spiral will be described as a preferred embodiment.

The information recording surface 7 is covered with a highly reflective film so that the reflections and antireflections of the light reflection element 10 and the antireflection element 11 can be respectively large.

In short, the video disc player 1 comprises an apparatus for optically reading information recorded on the surface of the video disc 5, which collides with the information recording surface 7 of the video disc 5. There is a light source, i.e., a read laser 3, for generating a read flux flux 4 to be described. The optical system 2 advances the reading line flux from the reading laser 3 to the information recording surface 7 along a constant optical path. A pair of movable mirrors 26 and 28 form part of this optical path. The first movable mirror 26 is positioned at a distance to the opposite side with respect to the second movable mirror 28 so that the read flux 4 is It may be reflected at least once in each movable mirror 26, 28. The movable mirrors 26 and 28 may all be movable or only one of them may be movable, which is intended to adjust the read flux to reach the surface of the video disk 5 accurately.

In normal operation, the focused read flux 4 impinges on the continuously arranged light reflecting element 10 and the non-reflecting element 11 representing the frequency modulated signal. The antireflective element 11 is a light scattering element in the video disk 5. The reflected light flux 4 'is a modulated light flux, which is light corresponding to a frequency modulated signal represented by the light reflecting element 10 and the non-reflective element 11 formed on the information track 9. This reflection beam 4 'is focused by the microscope objective lens 17 after being reflected from the light reflecting element 10 and the non-reflecting element 11 which are continuously formed on the video disk 5. Reflected flux 4 'travels along a portion of the same path as when read flux 4' is incident.

In this case, the common path includes a second movable mirror 28, a first movable mirror 26, and a fixed mirror 24. In this common path, both the sign 4 and the sign 4 'are shown.

인 선형으로 편극된 선속으로 변화시킨다. 판독선속(4)과는 반대방향에서 파장판(22)으로부터 나오는 반사선속(4')은 선속분할 프리즘(20)을 통과하는데, 이 프리즘(20)은 90

로 위상변이된 반사선속(4')을 분류발산시켜서 신호재생부 시스템(30)에 입사시킨다. 프리즘(20)은 판독선속(4)과 반사선속(4')을 광학적으로 분리시킨다. 이 신호재생부 시스템(30)은 방사방향 추적오차 신호를 발생시킨다.The reflected beam 4 'then passes through a quarter wave plate 22, which has a circularly polarized line flux of 90%.

Is changed to linearly polarized line velocity. Reflected flux 4 'coming from the wave plate 22 in the direction opposite to the read flux 4 passes through the beam splitting prism 20, which is 90

The divergent reflected beams 4 'are classified and diverged to enter the signal regeneration unit system 30. Prism 20 optically separates reading flux 4 and reflecting flux 4 '. The signal regeneration unit system 30 generates a radial tracking error signal.

One function of the beam splitting prism is to prevent the entire reflection beams 4 'from being fed back into the read laser 3 again. When the reflected flux 4 'is returned to the read laser 3, the mechanism by which the read laser oscillates to a constant operating mode is disturbed. Therefore, the beam splitting prism 20 readjusts most of the directions of the reflection beam 4 'in order to prevent the feedback action in which the reflection beam 4' is returned and affects the read laser 3. Let's do it. In the case of the solid-state laser, it is hardly affected by the feedback of the reflected beam 4 ', in which case it is not necessary to use the beam splitting prism 20. The solid state laser may serve as a light detector portion of the signal regeneration unit system 30.

In the video disc player 1 illustrated in FIG. 1, the normal operation of the signal reproducing unit system 30 is to send a plurality of signals to other circuits forming part of the video disc player 1.

The first kind of these signals is an information signal representing the accumulated information, and the second kind is a control signal which is derived from the information signal and controls the movable mirrors 26 and 28. The information signal is a frequency modulated signal representing information accumulated in the video disk 5. This information signal is sent to the frequency modulation processing unit system 32 via the conductor 34. The focus servo system is indicated by reference numeral 36. The mirror control signal generated by the signal reproducing unit system 30 is a radial mirror control signal applied to the radial tracking mirror control unit system 40 via the conductors 41 and 425.

떨어져 설치되어 있다. 각각의 회전속도계 요소는 공지된 바와 같은 출력펄스를 발생한다. 이들은 각각에 대하여 180

의 위상차를 갖도록 설치되었기 때문에 회전속도계 바퀴를 설치함에 있어서의 결점을 상쇄한다. 도선(51)은 제1회전속도계 요소가 발생시킨 연속펄스를 스핀들 서어보부 시스템(50)에 전달하며, 도선(52)은 제2회전속도계 요소가 발생시킨 회전속도계 펄스를 스핀들 서어보부 시스템(50)에 전달한다. 스핀들 서어보부 시스템(50)이 예정된 회전속도, 즉 1799. 1rpm에 도달하게 되면, 이 스핀들 서어보부 시스템(50)은 도선(54)상에 플레이어 작동신호를 발생시킨다. 회전속도가 정확히 1799. 1rpm이 되면, 30프레임의 TV 정보가 표준규격의 TV 수상기에 나타날 수 있다.When the video disc player 1 is operated, the first function of the video disc player 1 is to activate the read laser 3 (FIG. 2) and the spindle motor 48 to operate the spindle. Reference numeral 49 and the video disk 5 installed therein are rotated. The rotational speed of the spindle 49 installed in the spindle motor 48 is controlled by the spindle servo system 50. A spindle tachometer (not shown) is connected to the spindle 49 to generate an electrical signal indicative of the current rotational speed of the spindle 49. The tachometer consists of two pick elements, which are 180 relative to the spindle 49.

It is installed apart. Each tachometer element generates an output pulse as known. These are 180 for each

Since it is installed to have a phase difference of, the defect in installing the tachometer wheel is offset. The conductive wire 51 transmits the continuous pulse generated by the first tachometer element to the spindle servo system 50, and the conductive wire 52 transmits the tachometer pulse generated by the second tachometer element to the spindle servo system 50. To pass). When the spindle servo system 50 reaches a predetermined rotational speed, ie 1799. 1 rpm, the spindle servo system 50 generates a player actuation signal on the lead 54. When the rotation speed is exactly 1799. 1 rpm, 30 frames of TV information can be displayed on a standard TV receiver.

The second main function of the video disc player 1 is to operate the carriage servo system 25.

As described above, in order to read the frequency-modulated encoded information from the video disk 5, the read flux 4 is focused on the light reflecting element 10 and the non-reflecting element 11 in the video disk 5. It is good to enter. For best results, the read flux 4 must be incident at right angles to the plane with the encoded information. To achieve this shape, relative movement between the optical system 2 and the video disk 5 is required. In other words, the reading flux 4 is fixed and the video disk 5 is moved, or the video disk 5 is fixed and the optical system 2 is moved relative to the video disk 5.

In the embodiment of the present invention, the optical system 2 is fixed and the video disk 5 is moved under the read line flux 4. The carriage servo system 55 controls the relative movement between the video disk 5 and the optical system 2.

The carriage servo system 55 gives flexibility to the overall function of the video disc player 1 by instructing relative movement in various different modes of operation as described above.

In the first mode of operation, the carriage servo system 55 moves the carriage device 56 in response to the player operating signal applied through the conductor 54 to read the read fluxes 4 in a direction perpendicular to the information recording surface of the video disc 5. ) Will collide. Note that the term carriage device is used to distinguish the structural elements on which the video disk is placed. The carriage device 56 includes a spindle motor 48, a spindle 49, a spindle tachometer (not shown), a carriage motor 57, and a carriage tachometer generator 58.

In the block diagram illustrated in FIG. 1, the carriage device is not specifically shown in order to avoid complexity. In order to summarize the operation of the video disc, it should be noted that the function of the carriage servo system is to move the carriage to the initial position where the rest of the player's functions begin sequentially. The carriage servo system may position the carriage at any number of fixed positions relative to the video disk, depending on the design requirements of the system. For carriage purposes, the carriage may be located at the beginning of a frequency modulated signal recorded on the video disk. Shall be. The carriage motor 57 generates a driving force for moving the carriage device 56. The carriage tachometer generator 58 is a current source for generating a current indicating the moving direction and the instantaneous speed of the carriage device.

When the spindle speed reaches 1799. 1 rpm, which is possible by the spindle servo system, a player operating signal is generated in the lead wire 54, which controls the relative movement between the carriage device 56 and the optical system 2. Is delivered to the carriage servo system. The next procedure after the operation has started is that the focus servo system 36 controls the movement of the lens 17 relative to the video disk 5. The focused servo system is specifically illustrated in FIG. 7. This focusing servo system 36 applies a varying force to the readhead in a direction perpendicular to the video disk 5 so that the distance between the readhead and the video disk 5 is constant regardless of the radial position of the readhead. Used to maintain

The function of the connection servo system 36 is to adjust the distance between the lens 17 and the video disk 5 appropriately, so that it is reflected from the video disk 5 to reflect the light reflecting element 10 and the non-reflecting element 11. This allows the lens 17 to focus the maximum amount of light of modulated light.

The tangential servo system 60 receives the first input signal transmitted from the frequency modulation processing system 32 via the lead 62. The input signal on the conductive line 62 is a frequency modulated signal detected by the lens 17 from the surface of the video disk 5, and amplified by the signal reproducing unit system 30, and the frequency modulated processing system by the conductive line 34 ( 33).

The function of the tangential servo system 60 is to adjust the signal detected from the video disc 5, i.e. the tangential error caused by the eccentricity of the information track 9 on the video disc 5 It is to correct the errors of other errors introduced in the detected signals due to the physical defects of the video disc 5 and mechanical defects interposed in the video disc player. The tangential servo system 60 compares the signal read from the video disk 5 with the signal of the local oscillator and performs its function. The difference between these two signals represents the instantaneous error of the signal read out by the video disc player 1.

More specifically, the signal read out from the video disk 5 is a signal that has been carefully recorded on the video disk while maintaining the phase for other signals recorded together. In the frequency modulated signal of color TV, the signal is a color division part of a video signal. The local oscillator's signal is a crystal-controlled oscillator operating at a color subcarrier frequency of 3.579545 MHz. The tangential servo system 60 detects the phase difference by comparing the color branch signal with the color carrier vibration frequency. This phase difference is used to correct the phase of the next FM information string that also contains a color branch signal. In order to perform continuous tangential time axis error correction on the signal read out from the video disc, the phase difference of successive angular columns is generated in the same manner.

In the accumulation information signal having no portion corresponding to the color branch signal, a signal having a phase relative to another signal on the video disk 5 can be periodically added to the information at the time of recording. In the reproducing operation, this signal is selected from the recorded information section and compared with the signal of the local oscillator corresponding to the color carrier oscillator. In this way, the tangential time axis error correction can be performed on any signal recorded on the video disk.

The error signal detected by comparing the signal read out from the video disk 5 and the frequency of the color carrier carrier oscillator generated internally is sent to the second movable mirror 28 through the conductors 78 and 80. The signals on the conductors 78 and 80 actuate the second movable mirror 28 to move the read-out flux 4 back and forth along the information track in the direction of the arrow 14 so that the video disk 5 is moved. Allows time-base errors caused by defects in manufacturing or reading to be corrected.

Another output signal from the tangential servo system is the motor reference frequency applied to the spindle servo system 50 via the lead 72. As such, the generation of the motor reference frequency in the tangential servo system 60 is convenient due to the presence of the frequency of the color carrier oscillator used in the comparison operation as described above. The frequency of the color carrier oscillator is a signal that is accurately generated. It is divided into the motor reference frequency used to control the spindle servo speed. When the color carrier frequency is used as the frequency for the spindle speed control, the speed of the spindle is effectively fixed to this color carrier frequency, so that the information detected from the video disk 5 can be accurately displayed on the TV receiver 76 with maximum fidelity. The spindle will rotate at the frame frequency.

The output signal from the radial tracking mirror control system 40 includes a first radial mirror tracking signal applied to the lead wire 68 and a second radial mirror control signal applied to the lead wire 70. Mirror control signals on the leads 68, 70 are applied to the first movable mirror 26, which is used for radial tracking purposes. The control signal on conducting wires 68 and 70 moves the first movable mirror 26 so that the read-in flux 4 impinging thereon moves in the radial direction and is illuminated by the focused light spot 6. (9) It should be located at the center of phase.

The output from the spindle servo system 50 is applied to the spindle motor 48 via the lead 82.

The output generated by the carriage servo system 55 to drive the carriage motor 57 is applied to the carriage motor 57 via the lead 84. The current generated by the carriage tachometer generator 58 indicates the rotational direction and the instantaneous speed of the carriage and is applied to the carriage servo system 55 through the conductor 86.

The first output signal from the frequency modulation processor system 32 enters the audio processor system 88 via the lead 90. The signal on lead 90 is a frequency modulated video signal from a distribution amplifier in frequency modulation processor system 32. The other output signal from the frequency modulation processor system 32 is applied to the radio frequency modulator 92 via the lead 94. Conductor 94 passes a video output signal generated from a frequency modulation detector portion of frequency modulation processor system 32.

The output signal of the audio processing system 88 is applied to the radio frequency modulator 92 via the lead 96. The output signal applied to the radio frequency modulator 92 via the lead 96 is a carrier frequency of 4.5 MHz modulated by the audio information, which is a channel frequency oscillating at the center frequency corresponding to one channel of the TV receiver. Modulate the oscillator. The modulated channel frequency oscillator output enters the standard TV receiver 76, and the internal circuit of the TV receiver demodulates the audio signal included in the modulated channel frequency signal.

The output of the audio processing system 88 modulates the output of the frequency oscillator corresponding to channel 3/4 before being applied to the standard TV receiver 76. Although channel 3/4 is selected for convenience, the frequency of the channel frequency oscillator may be appropriately selected for any channel of the standard TV receiver 76. The output of the radio frequency modulator 92 is applied to the TV receiver 76 via a lead 98.

3 shows an example in which the optical system 2 is installed on the movable arm 100. The movable arm 100 is also provided with a read head 102. This movable arm 100 is supported by a rotating element 104 which rotates the readhead 102 radially with respect to the tangential surface 7 of the disc and in a direction perpendicular to the drawing. It moves along the arc of. The video disk 5 is supported by the tentable 106.

In operation, the read laser 3 injects the read flux 4 to the information recording surface 7 of the video disc 5 via the optical system 2. The information recorded on the video disc interacts with the incident light flux to generate a reflected light flux containing the recorded information. The reflection flux returns to the signal reproducing unit system 30 through the optical system 2. The signal reproducing system 30 analyzes the information possessed by the reflecting flux 4 'so that the read flux 4 is the information track. It is determined whether or not (9) is properly tracked.

If it is determined that the light point 6 of the laser is not incident on the predetermined portion of the information track 9, the collision point of the reading flux 4 is moved in the radial or tangential direction when applied to the read head 102. In this way, an appropriate servo signal is generated so that the information track 9 being read and the reading flux flux 4 coincide.

Alternatively, the position of the laser light spot 6 may be moved by controlling the drive of the rotating element 104 of the video disc player 1 with a servo signal. As another method, the motor may be connected to the turntable so that the radial motion is increased by a certain amount every turn of the turntable 106. In either case, the readhead 102 makes rough adjustments to the drive of the rotating element 104 and at the same time makes fine adjustments to the movable mirror while the information track 9 is recorded on the video disc 5. ).

A cam and cam follower assembly 108 (which will be described in detail with respect to FIG. 7) is installed on the rotating element 104 so as to interact with the movable arm 100 via the flexible cable 110. Get in touch.

As shown in FIG. 4, a read laser 3 is used as a light source for generating a read flux of light for light radiation. The optical system 2 is used as a line speed directing circuit for optically defining the direction of the read line flux from the read laser 3 to the information track 9 along the path of the read line flux 4. The path of the read flux 4 consists of a first portion 4a, a second portion 4b and a third portion 4c. The first portion 4a is a portion only the reading flux 4 travels. The second portion 4b is a portion in which both the read fluxes directed to the video disc 5 and the reflected fluxes from the video disc 5 to the flux separation circuit 111 proceed, which is the second flux separation circuit 111. The reflection flux 4 'in the portion 4b is separated and proceeds to the third portion c. The third portion 4c extends from the beam splitting prism 20 to the photosensitive element 112 for sensing the reflected beam 4 '.

When the reading flux 4 collides with the information track 9, the reading flux 4 is modulated by the light reflecting element 10 and the non-reflecting element 11. The reflected and reflected beam flux 4 'is thus returned along the second portion 4b of the flux path.

The beam separation circuit 111 includes a beam splitting prism 20 and a quarter wave plate 22 disposed between the prism 20 and the video disk 5. The path of the flux is formed to follow the folded U-shaped optical path and reach the video disk 5. The second part 4b which is common to the reading flux line and the reflection flux forms at least a part of one leg portion of the U-shape.

3 and 4, it can be seen that the first and second portions of the beam path in the optical system 2 are formed perpendicular to the disk surface. The second part connects the first part and the third part. The fourth part is connected to the information track 9 at the leg end of the third part. The other end of the first part is connected to the read laser 3. Thus, it can be seen that the first portion is parallel to the third portion, the fourth portion is perpendicular to the first portion and the third portion, and also perpendicular to the information recording surface 7 of the disc.

As can be seen in FIG. 2, the fourth part comprises movable mirrors 26 and 28 and a lens 17 starting from the fixed mirror 24. The first movable mirror 26 changes the path of the reading flux 4 with respect to the information track 9 in the information recording surface 7 of the disc, so that the reading flux 4 is in the tangential direction along the information track 9. It is intended to be moved to.

The lens 17 is a microscope objective lens and is provided on the read head 102. The lens 17 focuses the read flux 4 on the selected information track 9 and also allows the reflected flux to pass through the photosensitive element 112 along the second portion 4b, which is a common flux path portion. Can be adjusted accordingly. The fixed mirrors 114 and 116 are used to direct the first portion 4a of the beam path to the lens 15.

In the readhead 102 specifically illustrated in FIG. 4 there is a fluid bearing element 118, which is supported by the lens 17 adjacent to the lens 17 and thus in the limited range of this lens 177. Vertical direction adjustment is possible. 4 also shows an embodiment in which a second movable mirror 28, which is a tangential tracking mirror, is used together with the second fixed mirror 120 and the first fixed mirror 24. FIG.

The read flux 4 is reflected at least once from the movable mirror 28 before entering the lens 17. 4 shows two reflections of the flux. Similarly, the reflective beam 4 'conveyed from the information recording surface 7 of the video disk 5 is also reflected twice from the movable mirror 28, and also through the first fixed mirror 24, the photosensitive element 112 It is also illustrated that two reflections from the fixed mirror 120 before entering the optical path to the.

In the illustrated embodiment, the movable mirror 28 is provided at the pivot point 122 which is centered with respect to the movable mirror 28. The movable mirror 28 may be oval in which the planar direction of the drawing is long axis and the direction orthogonal to the plane of the drawing is short axis. At one end of the movable mirror 28, a mirror driving device 124 is attached, so that the pivot point for moving the reading flux 4 in the tangential direction such as arrow 14 shown in FIG. 122) It is possible to exercise around.

If the mirror drive device 124 rotates the movable mirror 28 in the clockwise direction in FIG. 2A, the collision point of the reading flux 4 is moved upward. This indicates that the ship speed moves along the arrow 14 in the first tangential direction. If the mirror drive 124 rotates the movable mirror 28 counterclockwise, the point of impact of the reading flux 4 is at the first tangent along the lower (ie arrow 14) in FIG. 2b. In the second tangential direction opposite to the direction].

The incident read flux 4 and reflect flux 4 'travel along the same path between the information recording surface 7 of the video disc 5 and the beam split prism 20. The movable mirror 28 serves to adjust the reading point to a predetermined position so that only the illuminated part is read. The reflected flux 4 'is reflected back to the signal reproducing subsystem 30.

Also, in another embodiment, not illustrated, the two mirrors 28 are adjusted before the reading flux 4 enters or exits the information recording surface 7 by adjusting the movable mirror 28 and the fixed mirror 24. Reflections may occur multiple times between 120. In such a configuration, it is possible to further reduce the magnitude of the rotation of the mirror necessary to properly adjust the reading point. Therefore, the mirror drive device 124 may apply only a small force to the movable mirror 28.

As shown in FIG. 2A, the movable mirror 28 and the mirror at the end of the long axis in driving the second movable mirror 28 at the pivot point 122 and driving around the axis orthogonal to the plane of FIG. The drive unit 124 is coupled to allow rotation in a clockwise and counterclockwise direction. The second mirror driving device 126 is connected to one end of the first movable mirror 26 to allow the movable mirror 26 to rotate around the long axis 128 located on the plane of FIG.

In actual operation, the second mirror drive 126 moves the read flux 4 radially to enable fine tracking of the information track. By using the first mirror driving device 124 to move the ship speed in the circumferential direction along the direction indicated by the arrow 14 in Fig. 2b, tangential tracking is possible, thereby improving time synchronization and eccentricity. Allow compensation of rates.

Mirrors can be used in various ways for different purposes. When the fixed mirror 120 is used in combination with the movable mirror 28, only the position adjustment in the radial direction can be performed. By selectively controlling the movable mirror 28, the read line flux 4 can be adjusted to the correct position on the information recording surface 7 of the video disk 5. When the first movable mirror 26 is used in combination with the second movable mirror 28, both the adjustment in the radial direction and the tangential direction can be performed. In the arrangement as described above, each mirror is positioned to face each other. As a first example, each pair of mirrors 26, 28, 120, 28 may be arranged such that the read flux 4 and the reflect flux 4 'are reflected once from each mirror in the incident and reflecting paths, respectively. have. As a second example, each pair of mirrors 26, 28, 220, 28 may be arranged such that multiple reflections occur with respect to the path of incidence to the reading flux 4 and the path of reflection to the reflecting flux 4 '. have.

Each mirror 26, 28, 120 has a reflecting surface, with the reflecting surface in each mirror in the combined case being parallel to the reflecting surface of the other mirror.

In the arrangement shown in FIG. 10, the reflecting surface in each mirror in the combined case is present in the converging surface. Because of the convergence angle between the reflecting surfaces, the read line flux 4 makes a plurality of reflections in the direction of convergence and then a number of reflections in the direction opposite to the convergence direction.

Referring back to FIG. 5 where the radial tracking mirror control subsystem 40 is shown, the reflected flux 4 'impinges on the photosensitive element 112. If the information track 9 is properly tracked at the point 6 in the outer middle of the information track 9, an output signal of constant magnitude is generated. The output of the photosensitive element 112 is supplied to the addition circuit 130 via the lead 132. Also, the variable bias signal is supplied from the bias source 134 to the other input of the addition circuit 130 through the conductive line 136. By adjusting the bias source 134, a zero output can be generated when the signal on the lead 132 is at a predetermined maximum level. Some components of the error signal output from the adding circuit 130 through the conductive wire 66 are applied to the phase and amplitude compensation elements 140, and the output compensated therefrom is supplied to the radial mirror driving device 126. This allows the read flux 4 to track the information track 9. Since the component supplied to the mirror driving device 126 via the phase amplitude compensation element 140 is a relatively high frequency component among the error signals, the present invention will call this a dynamic error component. The static error component, which is the remaining component of the error signal, is applied to the carriage servo system 55, which will be described with reference to FIG. 6C.

However, if the information track 9 is not properly tracked, the energy impinging on the photosensitive element 112 is in a state different from the bias supplied by the bias source 134. Therefore, the output of the phase and amplitude compensation element 140 is supplied to the mirror driving device 126 in order to send an error signal of an appropriate polarity to correct the position of the light spot 6 with respect to the information track 9. If the bias signal is large, the light spot is moved toward the periphery of the disc. If the received signal is large, the light spot is moved toward the center of the disk. When the light spot 6 properly tracks the helical information track 9, the differential output becomes zero. In this example, the mirror drive 126 causes the read flux 4 to move radially at a predetermined speed.

The output of the phase and amplitude compensating element 140 becomes a correction signal for correcting the rate at which the read line flux 4 moves to the center. As another case, if the read line flux 4 is driven completely by the output of the phase and amplitude compensating element 140, the observed state will not be of practical importance. If a larger bias signal causes light spot 6 to move towards the center of video disk 5, light spot 6 will track the information track along its inner circumference. On the other hand, when a larger bias signal moves the light spot 6 to the periphery, the light spot 6 is tracked along the outer periphery of the information track 9. In either case, correcting the error signal imparts an appropriate force to the mirror drive 126 so that the read flux 4 tracks the information track 9.

The radial tracking circuits shown in FIGS. 5 and 9 include electrical circuit elements responsive to the position of the reading flux relative to the predetermined periphery of the information track 9 so that the reading flux is in a smaller range than the previously described predetermined periphery. Collision generates an electrical output variable that represents the opposite polarity.

The electrical circuit element includes an addition circuit and a bias source. The addition circuit has a pair of inputs and one output. The output of the bias source is used as one of the inputs of the addition circuit. A reflective flux 4 'is incident on the photosensitive element, and the output of the photosensitive element is used as the second input of the addition circuit. The output of the addition circuit represents the difference between the input from the photosensitive element and the input from the bias source.

The photosensitive element supplies a voltage output proportional to the light received from the information track 9. The bias source is an adjustable bias voltage source. The output from the addition circuit is a voltage proportional to the difference between each photosensitive element and each input from the bias source. The bias source can be adjusted such that the output becomes zero when the reflected flux 4 'impinges on the predetermined perimeter, and the known reflected flux 4' is detected by the photosensitive element.

The output of the addition circuit is supplied to the phase and amplitude compensation elements to send an output signal to the mirror driving device 126 which controls the movable mirror 26 so that the light spot 6 on the information track 9 can move relative to the radial direction. To do it.

FIG. 6A is a general block diagram of the spindle servo subsystem 50. One of the functions of the spindle servo subsystem 50 is that the spindle motor 48 has a constant rotational speed, ie, 1799. 1 rpm. It is to maintain a constant rotational speed of the spindle (49). This rotation speed is selected to suit the scanning frequency of the standard TV receiver. A standard TV receiver requires 30 frames per second, and when recording information to a video disc, one frame is fully accommodated in one spiral or track. If the time condition of the TV set or TV monitor is different from this standard, it indicates the function of the spindle servo system to maintain a constant rotational speed according to the new standard.

A start-up pulse activates the spindle motor 48, and as the spindle motor rotates, the input signal pulse train of the first tachometer passes through the lead 51 to the Schmitt trigger. Is applied to 150. The input signal pulse train of the second tachometer is applied to the second Schmitt trigger 152 through the conductive wire 52. A motor reference frequency of 9.33 KHz is applied from the tangential servo subsystem 60 to the third Schmitt trigger 154 via lead 72.

The output of the Schmitt trigger 150 is applied to the edge generator 157, and the output of the Schmitt trigger 152 is applied to the edge generator 160. The output of the Schmitt trigger 154 is applied to the edge generator 155. Each edge generator 157, 160, 155 is used to generate sharp pulses at the positive and negative edges of the signal applied to each.

The output of the edge generator 155 is applied to the phase and frequency detector 167 as a reference phase signal and to another phase and frequency detector 168 as well. The second input signal of phase and frequency detector 167 is the output from edge generator 157 and the second input signal of phase and frequency detector 168 is output from edge generator 160. By operation of the phase and frequency detector, the phase or frequency difference between the tachometer input signal and the motor reference frequency is displayed. The output of phase and frequency detector 167 is applied to adder circuit 169, and the output of phase and frequency detector 168 is also applied to the second input of adder circuit 169. The output of the addition circuit 169 is applied to the lock detector 170 and the power amplifier 171. The function of the lock detector 170 is to indicate whether the speed of the spindle has reached a constant rotational speed, which is achieved by sensing the output signal of the addition circuit 169.

The rotational speed of the spindle motor must reach a predetermined speed before the carriage unit is activated. When the video disk reaches a relatively high rotational speed, the video disk is placed in the air cushion and rises slightly perpendicular to gravity. In addition, the centrifugal force of the video discs makes the video discs somewhat flat. The vertical movement of gravity caused by the air cushion on the video disk and the vertical synergism caused by centrifugal force move the video disk from its original position to a stable position. It will be in a predetermined position with respect to the element. The motion of a video disk rotating at 1799. 1 rpm with a constant weight and specific gravity can be calculated so that the video disk maintains a constant distance with respect to all internal elements to avoid any unnecessary contact. Contact between the video disc and the body of the video disc player causes friction to damage the video disc.

The lock detector 170 is configured to generate a player operating pulse on the conductor 54 when the phase fixation is achieved and the rotation speed of the spindle is completely at 1799. 1 rpm.

While the video disc player 1 is operating normally, the tachometer input signals are continuously applied to the Schmitt triggers 150 and 152 through the conductors 51 and 52, respectively. These actual tachometer input signals are compared with the motor reference frequency on the conducting wire 72, and the deviation circuit 169 detects the deviation and applies it to the power amplifier 171. The power amplifier 171 transmits a driving force to the spindle motor 48 through the conductive wire 82, so that the rotational speed of the spindle 49 is maintained at a predetermined speed.

The first input signal of the tangential servo subsystem 60 shown in FIG. 6B is applied from the frequency modulation processor system 32 via the lead 62. The signal on the lead 62 is a video signal from a video distribution amplifier in the frequency modulation processing subsystem 32. The video signal on lead 62 is sent to lead filter 173 via lead 174 and to burst gate generator 175 via lead 176.

The function of the decomposition filter 173 is to separate the color portion from the video signal received from the frequency modulation processing subsystem 32. The output signal of the decomposition filter 173 is applied to the phase detector 177 through the conducting wire 178, and the second input signal of the phase detector 177 from the color subcarrier oscillator circuit 179 via the conducting wire 180. Is added. The purpose of the phase detector 177 is to compare the instantaneous phase of the color signal with the phase of the color subcarrier oscillator signal generated extremely accurately in the oscillator circuit 179. The phase difference detected by the phase detector 177 is sent to the sample and hold circuit 181 through the lead 182, and the function of the sample and the hold circuit 181 is to transmit its chromatic signal. The voltage corresponding to the branch phase difference detected by the phase detector 177 is accumulated while the video information included is completely read from the video disk 5.

The branch gate generator 175 is for generating an operation signal indicative of the time for receiving the color branch portion of the video waveform from the frequency modulation processing subsystem 32. When the output signal of the branch gate generator 175 is applied to the sample and holder circuit 181 through the conducting wire 183, the operation signal on the conducting wire 183 transmits the output from the phase detector 177 to the color signal of the video signal. The sample and holder circuit 181 is applied during the time the signal appears.

The oscillator circuit 179 sends the color carrier to the divider 184 through the conductive line 185, and the frequency of the color subcarrier is divided into one third of 384 to generate a motor reference frequency. The motor reference frequency signal is applied to the spindle servo system 50 via the conductor 172.

The output of the sample and holder circuit 181 is sent to the auto gain control amplifier circuit 186 via a lead 187. The automatic gain control amplifier circuit 186 has a second input signal from the carriage position indicating device. The function of the signal on the conducting wire 188 is to change the gain of the automatic gain control amplifier circuit 186 when the reading line flux moves radially from the outer track toward the inner track or from the inner track toward the outer track. The necessity of adjusting the change according to the change in the radial position is because the light reflecting element 10 and the non-reflecting element 11 having different dimensions are formed in the outer track and the inner track.

The reason why the spin gain motor 48 must maintain a constant rotation speed is to provide 30 frames of information to the TV receiver 76 by rotating the video disk to make almost 30 revolutions per second. The length of the track at the outermost periphery is much longer than the length of the track at the innermost side. Since the same amount of information must be accumulated equally in the inner and outer tracks for one revolution, the size of the light reflective element 10 and the non-reflective element 11 should be different depending on the radius of the track. Therefore, due to such a change in size, it is necessary to adjust appropriately when processing the detected signal read out from the video disk 5.

One such adjustment is to adjust the time axis error as the read point changes radially from the inside to the outer periphery by adjusting the gain of the amplifier circuit 186. The carriage position indicating device (not shown) generates a sufficiently accurate reference voltage indicating the radial position of the point of impact of the reading flux 4 with respect to the video disk 5.

The output of the automatic gain control amplifier circuit 186 is applied to the phase and amplitude compensation circuit 190 via the lead 189. The phase and amplitude compensation circuit 190 is intended to stabilize the servo system. The output of the phase and amplitude compensation circuit 190 is sent to the tangential mirror drive 192 via a lead 191, which mirrors the radial mirror drive described above with reference to FIG. It is comparable. The mirror drive 192 consists of a pair of push-pull amplifiers (not shown), the output of the first push-pull amplifier being a tangential movable mirror via lead 78. 28, and the output of the second push-pull amplifier is sent to the tangential movable mirror 28 via the lead 80.

The time axis error introduced in the reading process of the frequency-modulated video signal reproduced from the information recording surface of the video disc 5 is fixed in the tangential servo subsystem 60. The time axis error is introduced in the reading process due to the defect of the video disk 5. The time axis error causes a slight phase change in the reproduced video signal. A typical time base error fixer includes a highly precise oscillator that generates a signal to be used as a phase reference for comparison. In a preferred embodiment of the present invention, a precise oscillator is configured to oscillate at the color subcarrier frequency. The output of the highly controlled oscillator is compared with the color splitter signal of the color video signal. In another embodiment, a highly accurate frequency signal having a randomly selected frequency is recorded and compared to this in the reading process with the frequency of the correct oscillator of the video disc player and used for the same purpose by detecting the phase difference between the two signals. Can be.

The color branch signal forms part of the reproduced video signal. The color branch signal is repeated for each lead of the color TV video information of the recovered video signal. In a preferred embodiment of the present invention, the presence of a phase error is detected by comparing each part of the color branch signal with an accurate subcarrier oscillator. In another embodiment, such a comparison is performed by sampling at a predetermined position of a signal corresponding to the color branch signal or irregularly sampling without performing each color branch signal or corresponding signal. If the recorded information is not sensitive to phase error, it may be compared at wide intervals. In general, the phase difference between the recorded signal and the local oscillator signal is repeatedly sensed at regular intervals on the information recording surface to adjust the phase difference of the reproduced signal. This repetitive detection of the phase difference is performed for each lead of the video signal.

The detected phase difference is accumulated until the next sampling, and this phase error is used to adjust the read position of the read line flux on the video disc to be at the position where the phase error is fixed.

By repeatedly comparing the recorded signal with the highly accurate frequency of the local oscillator, the next part of the video signal reproduced during the sampling period is adjusted.

As the read flux traces the information recording surface of the video disc 5 in the radial direction, the phase error changes. An additional signal is required to adjust the phase error according to the instantaneous position of the read line for adjusting the phase error due to the instantaneous position on the information recording portion of the video disc 5. This additional signal is due to the change in the physical size of the information display element formed on the video disc as the tracking position changes from inside to outside in the radial direction. Since the same amount of information must be recorded both inside and outside, the size of the internal information display element must be smaller than the size of the external information display element.

If the size of the information display element is the same in the inner and outer radius, this additional signal for adjusting the instantaneous radial position is not necessary. Such a case is possible in a strip-shaped member in which information is recorded using an information display element of the same size, rather than a disc-shaped information storage member.

The tangential movable mirror 28 serves to correct the time axis error introduced due to the mechanical operation of the reading system. These mirrors are electronically controlled and change the phase of the reproduced video signal read out from the video disc by changing the time axis when reading the signal from the video disc. This operation is accomplished by reorienting the mirror to read information from the video disc ahead or behind in time as compared to the time or spatial interval during which the phase error is detected. The position is changed by the degree of phase error, thereby changing the time for which information is read.

If the phase error is not detected at all by the time axis error fixing device, the collision point of the read line flux with respect to the information recording surface of the video disk 5 is not moved. When the phase error is detected in the comparison period, a signal for changing the collision point is generated. Therefore, the playback information from the video disc is used at a point ahead or behind in time compared to the comparison period. In a preferred embodiment of the present invention, such an operation is achieved by changing the spatial position of the point where the reading flux crosses the information recording surface of the video disk 5.

It is effective to correct the phase error associated with the time axis error for both circular and spiral information tracks of the tangential servo subsystem 60. The basic function of the tangential servo subsystem 60 is to identify and detect the position where the reading flux 4 collides with the information recording surface 7 of the video disk 5. This function operates on the radial tracking error and adjusts the position of the reading flux 4 circumferentially to accurately rearrange the collision contact of the information track 9 and the reading flux 4 so that the phase error associated with the time axis error can be adjusted. By compensating, it is processed electronically. The circumferential adjustment described above is made using the tangential movable mirror 28. The electronic output of the tangential servo subsystem 60 adjusts the runout point of the reading fluxes 4 circumferentially along the information track 9 of the video disc 5 and rotates the movable mirror 28. Used as input to directional mirror drive.

As shown in FIG. 6C, in a carriage servo subsystem suitable for providing a relative movement between the information recording surface 7 of the video disk 5 and the readhead 102, the power supply 200 is connected to the video disk (see FIG. Generates a constant current necessary to control the relative movement between the information recording surface of 5) and the readhead 102 at a constant rate, thereby focusing continuously at the center of the information track 9 of the video disk on which the light spot 6 is rotating. Be sure to

As mentioned above, the information track 9 is a continuous spiral. In the embodiment illustrated in FIG. 1, a movable carriage device 56 and a stationary read laser 3 are used. The distance between the centers of adjacent spirals in an information track is typically 2 microns. Therefore, when sufficient current is generated in the power supply 200 so that the video disk 5 is completely rotated once, the carriage device 56 is used by 2 microns in the axial direction. This power supply roughly controls the relative motion between the readhead 102 and the information track 9. Fine adjustment of the carriage speed is determined by the voltage valve from the tracking servo.

The output of the power source 200 is applied to the addition circuit 202 through the conductor 204, and the output of this addition circuit 202 is applied to the power amplifier 206 via the conductor 208, and the power amplifier 206. The output from) is applied to the carriage motor 57 via the lead 84. The dotted line 212 between the carriage motor 57 and the carriage tachometer generator 58 indicates that these devices are mechanically connected. The output temperature line 86 from the carriage tachometer generator 58 is applied to the addition circuit 202. In addition, the remaining components of the error signals output from the addition circuit 130 in the radial tracking mirror control sub-system 40 of FIG. 5 through the lead 66 are also added to the adder circuit 202 to provide the lead wire 204. The error signal component on the conductor 66 applied to the addition circuit 202 is changed very slowly as a DC offset signal. This is called the static error component. This static error component, together with the dynamic error component already described with FIG. 5, constitutes an error signal.

When the start signal is sent to the power source 200 through the conductor 214, the power source 200 sends a constant current to move the carriage device 56 from the initial stop position to the start point of the track. As described above, the carriage device 56 and the optical system 2 make relative motion. In the standard mode of operation, the movement of the optical system 2 and the carriage device 56 causes the reading flux 4 from the reading laser 3 to collide with the starting point of recording of the information. Thus, the power supply 200 generates a current to be applied to the addition circuit 202. The function of the addition circuit 202 detects the amplitude of the current generated by the power supply 200 and this and the amplitude of the current supplied from the carriage tachometer generator 58 to the addition circuit 202 via the conductor 86. To compare with. As described above, the current generated in the carriage tachometer generator 58 indicates the instantaneous speed of the carriage device 56. The conductor 208 is connected to a power amplifier 206 that generates the power required to move the carriage motor 57 to the required position by comparing the current on the lead 86 with the current of the power supply 200. Send through This power source 200 generates a constant bias current capable of moving the carriage device 56 by 2.0 microns each time the video disk is rotated. In addition to the bias current, a fine adjustment current from the tracking servo is applied to the addition circuit 202, thereby providing a constant current input signal to the power amplifier to move the carriage motor 57 by a predetermined distance every revolution. . This constant input bias current from the power supply 200 becomes the first fixed bias control signal for the carriage motor 57.

In operation, the carriage servo subsystem provides a means for moving the readhead 102 relative to the video disk 5. When using a spiral information track, this movement is done at a constant rate. When the information track 9 is formed using a plurality of concentric circles, such a moving circuit generates an incremental stepped movement between the read head 102 and the information recording surface 7 of the video disc 5.

The carriage servo subsystem roughly controls the relative movement between the readhead 102 and the video disk 5, which is read when the readhead 102 and the optical system 2 are mounted on the movable arm 100. The result of roughly adjusting the ship speed 4 with respect to the video disk 5 is also shown. Using the radial tracking mirror control subsystem 40, the radially movable mirror 26 and the mirror drive 126 to adjust the path of the read flux 4 relative to the readhead 102, 4) can be finely adjusted with respect to the video disk 5.

9 shows a block diagram of the signal regeneration subsystem 30 along with another example of a radial tracking mirror control subsystem 40. Reflected flux 4 ′ impinges on photosensitive element 112 composed of portions 216 and 218. The output of the photosensitive element 216 is applied to the first tracking preamplifier 220 via the lead 222, and the output of the photosensitive element 218 is connected to the second tracking preamplifier 224 via the lead 226. Is added. The output of the photosensitive element 216 is also sent to the adding circuit 228 via the lead wire 230, and the output of the photosensitive element 218 is also sent to the adding circuit 228 via the lead wire 232.

The output of the tracking preamplifier 220 is fed to the input of the differential amplifier 234 via the leads 112, and the output of the tracking preamplifier 224 is also the second input of the differential amplifier 234 via the leads 238. Is added. The output signal from the differential amplifier 234 via leads 240 and 242 is applied to the push-pull amplifier 244 via a phase and amplitude compensation element to push the mirror drive 126 to be applied. Generate full radial tracking error voltage.

The output of the addition circuit 228 is amplified in the wideband amplifier 246 before being applied to the frequency modulation processing subsystem 32 via the lead 34.

5 and 9 a radial tracking circuit is shown. The information track 9 in FIG. 2B is composed of a single spiral information track. Since the size of the light reflecting element 10 and the non-reflecting element 11 is relatively small, the portions of the information track 9 shown in FIG. 2B appear linear rather than circular. Each information track 9 in FIG. 2B is a respective loop of a helical track.

Another track forming method is a method of forming the information track 9 into a plurality of concentric circles, in which the read-out flux 4 moves between adjacent circles by adjusting the movable mirror 28.

Each pair of mirrors 120, 28 or mirrors 26, 28 is used to adjust the reading flux 4 to move radially on the information recording surface 7 of the video disk 5. The preferred position of the light spot 6 relative to the information track 9 is as shown in figure 2b. That is, in FIG. 2B, the light spot 6 is positioned at one contact of the information track 9 as the video disk 5 moves in the direction of the arrow 12. As shown in FIG. The radial tracking mirror control subsystem 40 shown in FIG. 5 allows the light spot 6 to be maintained on one side of the information track 9. The radial tracking mirror control subsystem 40 of FIG. 10 allows the light spot 6 to be maintained at the center of the information track. The radial direction is indicated by arrows 13 pointing to both sides. The radial tracking mirror control subsystem detects the position of the reading flux 4 on the information recording surface 7 of the video disk 5 with respect to the information track 9 so that the light spot is focused on the information track 9. When the light spot 6 moves toward the information track 9 'or the information track 9 ", the error tracking signal on the conductors 68 and 70 selectively controls the movement of the movable mirror 26 so as to read the speed of the reading. 4) Return to the selected information track 9 on the video disk 5 to perform radial adjustment.

The radial servo circuit shown in FIG. 5 or 9 detects the position of the reading flux 4 when the reading flux 4 collides with the information recording surface 7 of the video disk 5, and operates. Radiation of the read flux 4 to the selected information track on the video disc 5 by generating an error tracking signal to be applied to the movable mirror 26 by a mirror drive 126 that selectively controls the mirror 26. Allow direction adjustment.

3 shows an enlarged side view of the lens 17 and the air bearing device 255, which includes a readhead 102. The air bearing device 255 has a function as a path control element for the lens 17. The relative position of the lens 17 is formed so that the reading flux 4 is focused on the information track 9 to form the light spot 6. To adjust. The air bearing device 255 also focuses the reflection flux 4 'by adjusting the relative position of the lens 17, and also reflects the reflection flux 4' along the second portion 4b, which is a common flux path. Is passed through the photosensitive element 112. Readhead 102 includes a vertical element 256 having a horizontal element 257 at one end. The horizontal element 257 is for supporting the lens 17. Another vertical element 258 is fixed to the movable arm 100 by a bracket 259. The vertical element 258 of the movable arm 100 is connected to the vertical element 256 of the read head 102 via a pair of leaf springs 260 and 262. The spring force of the leaf springs 260 and 262 is generally insufficient to keep the spring in a horizontal position when the readhead 102 is not supported by the fluid bearings generated by the video disk 5. The fluid bearing element 118 and the lens 17 are included as part of the readhead 102. The combination of fixed mirrors and movable mirrors 26, 120, 28 is used to direct the flux from the reading laser 3 to the video disk 5 via the lens 17, the combination of mirrors being a lens 17 Is mounted to the movable arm 100 at the position closest to the inlet 16.

The support element 264 extends outward of the read head 102 toward the inner end of the movable arm 100. The support element 264 is provided with a bias spring 266, one end of which is fixed to the lever 268. The lever 268 is coupled to the movable arm 100, and is also connected to the cam and the cam ball device 108 via the flexible cable 110 (see FIG. 7).

Also included is an interlocking solenoid device (not shown) that works with the cam and the cam ball device, which is associated with the video disk 5 when the movable arm 100 is separated from the video disk 5. It prevents the readhead 102 from touching and also prevents the video disk 5 from being damaged even if it is significantly slowed for some reason while being tracked by the readhead 102.

The bias spring 266 acts like a rigid rod when it is retracted, such that the lever 268 moves the readhead 102 upwards so that the readhead 102 is away from the video disk 5 when necessary. It acts to make it work. Alternatively, when the readhead 102 is positioned on top of the video disk, the lever 268 rotates in the opposite direction while releasing the pressure of the bias spring 266. Under steady state, the weight of the readhead 102 is supported by the fluid bearing element 118 on the video disk, so that the leaf springs 260 and 262 can be leveled parallel to each other.

According to the present invention, a bias is added by the use of the bias spring 266 so that a constant distance is always maintained between the read head 102 and the fluid bearing element 118 and the information recording surface 7 of the video disk 5. do. As the movable arm 100 proceeds toward the center of the video disk, the relative surface speed changes, and the bearing capacity for the fluid bearing to support the readhead is reduced. Thus, if the bias spring 266 is initially extended by rotating the lever 268 downward, a downward force is applied to the support element 2640 so that the bias against the fluid bearing element 118 is increased when the fluid pressure is maximum. Is increased.

When the movable arm 100 moves inward of the video disk 5 and the surface speed decreases, the cam feeder rotates the lever 268 upwards to reduce the tension of the bias spring 266 and at the same time read it. Reduce the bias on the head 102. By appropriately selecting the shape of the cam, the bias of the fluid bearing element 118 can be maintained at an appropriate value to maintain a constant distance from the disk, even with respect to the disk surface velocity at any radial position.

The air bearing device 255 enables relative movement between the turntable 106 and the readhead 102 supporting the video disk 5. The mirrors 26, 28, 120, 28 and their respective servo subsystems 40, 60 and mirror drives 124, 126 are associated with the readhead flux in relation to the readhead 102. The role as a circuit which controls the path | route of 4) is shown. In detail, as the movable mirror 26 or the movable mirror 28 adjusts the paths of the read fluxes 4 in the tangential and lateral directions of the information track 9, respectively, the read fluxes 4 change the central axis. Thus passing through the readhead 102.

The cam and cam feeder 108 shown in FIG. 7 drives the lever 268 via the flexible cable 110 (also shown in FIG. 3). The cam 270 is movable arm 100. The cam hole 272 is positioned at the high protrusion at the outermost position of the c) so as to keep the read head 102 upward so as not to come into contact with the video disk 5.

When the movable arm 100 proceeds inward along the information track, the cam ball 272 proceeds toward the innermost point of the surface of the cam 270, with the maximum bias applied to the read head 102. . As the movable arm continues inward in the radial direction, the cam ball 272 reduces the biasing force on the readhead 102 as it slowly moves outward from the center of the cam 270.

Referring again to FIG. 8, the read head 102 in the illustrated video disc playback apparatus is located in an operating relationship with the turntable 106 supporting the video disc 5. The read head 102 is supported by the movable arm 100, ie the read head 102 is mounted on a vertical element 258 fixed to the movable arm 100 by a bracket 259. This installation is made through the leaf springs (260, 262). By doing so, the lens 17 can be held in close proximity to the information recording surface 7 of the video disk 5. By actuating the fluid bearing element 118 to the vertical element 256 of the readhead 102, the video disk 5 and the fluid bearing element 118 as the video disk 5 rotates on the turntable 106. As shown in FIG. Allow fluid bearing to occur between Bias spring 266 and lever 268 and cam and cam feeder 108 form an adjustable biasing device that can vary the force applied to readhead 102 in a direction perpendicular to video disk 5. As a result, the distance between the video disk 5 and the readhead 102 is kept constant regardless of the radial position of the readhead 102.

Leaf springs 260 and 262 are used to mount readhead 102 to vertical element 258. These leaf springs are insufficient to support the weight of the readhead 102.

The cam and cam feeder 108, which is part of the adjustable bias device described above, has the function of a bias control circuit. The cam and the cam feeder 108 are connected between the readhead 102 and the vertical element 256 and change the bearing force applied to the readhead 102 in response to the radial position of the readhead 102. Thereby compensating for the different bearing forces of the fluid bearing element 118 due to the different surface velocities which appear as the radius of the track varies.

The readhead 102 is fixedly connected to the fluid bearing element 118 and a fluid bearing is created between the fluid bearing element 118 and the video disk 5 so that the readhead 102 and the video disk 5 are separated from each other. A constant gap is formed between them.

The cam and cam feeder 108 exhibits the function of increasing the bearing capacity of the readhead 102 as the readhead 102 moves radially towards the inside of the video disc.

In the bias control circuit, there is a flexible cable 110 that connects the cam and cam feeder 108 to the bias spring 266. The bias spring 266 is a compression spring, and the function of the bias control circuit is to selectively compress the bias spring 256 so that the cam and cam feeder 108 immediately tracks the readhead.

Mechanical connection as shown in FIG. 8 serves to focus the focus of the objective lens 17 on the information display element, that is, the light reflection element 10 and the non-reflection element 11. The function of such a mechanical connection is to move the objective lens relative to the information recording surface 7 of the video disk 5 along the third portion 4c of the path of the reading flux 4 so that the video disk 5 Is to keep the reading flux 4 focused on the information track 9 as it moves laterally relative to the readhead 102.

10 shows a modification in which the movable mirror is provided in the read head 102. In this modification, the fixed mirror 120 and the movable mirror 28 are arranged on the converging surface. The reading flux which is incident in the horizontal direction impinges on the movable mirror 28, passes through a plurality of reflections between the movable mirror 28 and the fixed mirror 120, and is then rotated by 90 ° to descend to the reading apparatus. Similarly, the reflected line velocity will go through the same path. The movable mirror 28 is an articulated mirror, which refracts a line flux transmitted in a direction perpendicular to the plane of the drawing by rotating about an axis on the plane of the drawing.

회전시키므로 별도의 45

거울이 필요없게 되고, 따라서 비데오 디스크에 가해지는 광선의 세기를 증가시킬 수 있다. 물론, 이와 같이 하더라도 광선속의 질을 저하시킴이 없이 거울쌍의 사이에서 부가적인 반사가 최소한 한번 일어나도록 하여줄 수 있다. 제2도에서와 같은 반사횟수는 거울에서의 광의 손실을 작게할 수 있다.By controlling the angle of incidence of the fixed mirror 120 and the convergence angle between the fixed mirror 120 and the movable mirror 28, the incident flux can be reflected several times in two mirrors before entering the disk. Also, in addition to the flux path like this, a pair of mirrors

Rotates a separate 45

No mirror is needed, thus increasing the intensity of the light applied to the video disk. Of course, this also allows additional reflections to occur at least once between the mirror pairs without degrading the quality of the light beam. The number of reflections as in FIG. 2 can reduce the loss of light in the mirror.

While the present invention has been described with respect to specific embodiments, various modifications may be made without departing from the principles of the invention. For example, the movable mirror 28, as described above, is not necessarily limited to a mirror, but for example a movable mirror, movable lens, movable prism, or any other reflective element or refraction located within the optical path of the readout line. By moving the read line flux using a movable optical element such as a saint, the function of the present invention can be achieved.

Claims (1)

It is used in a video disc player for recovering information from a video disc, including an optical system 2 for directing the reading flux 4 to the surface of the video disc 5 along a predetermined optical path, and for reading out the video disc. A tracking device for controllably moving a ship speed, comprising: a carriage device 56 for moving a video disk with respect to an optical system at a selected movement rate, and a carriage servo portion for controllably moving the carriage device at the movement rate; The system 55, a movable mirror 26 for adjusting the path of the read flux to the optical system, and a dynamic error component connected to the movable mirror so as to control the movement of the movable mirror and the movement rate. Reading error rate by outputting an error signal having a static error component connected to the carriage servo subsystem Tracking device consisting of a radial tracking mirror control subsystem (40) for controlling the position of the controllable.

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