JPS58158079A - Video disk player - Google Patents

Abstract

PURPOSE:To facilitate control over the movement of the stylus of a pickup cartridge in speed search mode, and to evade noise appearing in video, by increasing the extent of the movement of the stylus per track. CONSTITUTION:The pickup cartridge 2 is supported and arranged by a pickup cartridge moving device 11 so that the lengthwise direction of an arm constituting the cartridge 2 and the direction of a track 1 interpose an adequate angle at the point the stylus 6 supported by a stylus holder 7 comes in contact with the track 1b on a disk 1. Consequently, the movement of the stylus 6 is controlled sufficiently even in speed search mode.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video disc player, and more particularly to a video disc player that uses a pickup cartridge detection method to play a grooveless video disc.

A video disc is a system for reproducing video and audio on a television receiver using the same principle as record koji, and various systems are currently being developed. One of them is to apply an extremely thin insulator to the surface of the conductor that forms the disk.
There is a method in which signals are recorded as extremely fine irregularities on an insulator without grooves, and a pickup cartridge detects and reproduces changes in capacitance.

FIG. 1 is a schematic top view showing a part of a disc and a pickup cartridge of a conventional pickup cartridge detection type video disc player, and the internal structure of the pickup cartridge is shown. Further, FIG. 2 is a front view of the schematic portion shown in FIG. 1.

In this configuration, a disk 1 on which video signals are recorded as tracks without grooves on both the front and back sides is placed with a hole 1a formed in the center thereof fitting into a protrusion at the center of a turntable (not shown). The pickup cartridge 2 includes a needle 6 supported by a stylus holder 7 provided at the tip of an arm 8 constituting the pickup cartridge 2.
is supported by the pickup cartridge moving member 11 so that the longitudinal direction of the arm 8 coincides with the direction of the track 1b at the point where it contacts the track 1b on the disk 1. The pickup cartridge 2 has coil supports 4a, 4b, 4c,
4d and both suspensions 9a and 9b formed of a rubber-like flexible material are provided, and coils 5a, 5b, 5c, and 5d are provided at the tips of each coil support, respectively.
A tapered arm 8 is provided on both the suspensions 9a and 9b, and a stylus holder made of an insulating material is provided at the tip of the arm 8 to support the needle 6. A small permanent magnet 10 is provided inside the arm 8.

Also, inside the foundation frame 3, an angle sensor 13 is installed on the support part 12.
provided through.

In operation, when the turntable rotates, the disk 1 mounted on it also rotates around the hole 1a. The pickup cartridge 2 electrically detects and reproduces the video signal recorded as unevenness of the insulator on the track 1b as a change in capacitance from the outer track on a straight line indicated by A-A' with a needle 6. do. As mentioned above, since the track 1b does not have a groove, a special position control signal is recorded on the track in advance to control the position of the needle 6 so as to follow the track. The tracks draw concentric circles around the hole 1a, and the needle 6 moves to an inner track each time it goes around one track.

The movement of the needle 6 along the straight line AA' is coupled with the movement of the arm 8 and the movement of the entire pickup cartridge 2. That is, each coil 5a, 5b based on the control signal recorded on the track.

A current flows through 50.5d, creating a clockwise rotational moment in the permanent magnet 10, causing the arm 8 to tilt inward and the hand 6 to move to the inner track. By repeating this movement, if the longitudinal direction of the arm 8 has an inclination angle of more than a certain degree with respect to the direction of the track 1b at the point where the needle 6 contacts the disk 1, the angle sensor 13 detects this and moves the pickup cartridge. The device 11 is operated to move the entire pickup cartridge 2 in the Y direction. Since the arm 8 also moves while the entire pickup cartridge 2 is being moved, the movement of the entire pink-up cartridge 2 is much faster than the movement of the arm 8. As a result, the pickup cartridge 2 returns to its original state a in which the longitudinal direction of the arm 8 coincides with the direction of the track 1b. By repeating the above operations, the position of the needle 6 moves along the straight line AA'.

As is well known, a video signal has a vertical effective scanning period necessary to form an image on the cathode ray tube and a vertical synchronization signal period during which no image appears on the cathode ray tube. 1st
In the diagram of the disk 1 shown in the figure, the section indicated by the angle 2.alpha. represents the vertical synchronization signal period 5-. If the above-mentioned movement of the needle 6 is performed in a section other than 2α, noise will be generated on the screen each time the needle 6 moves, so when the needle 6 is located within the section 2α, it will momentarily move to the next track. It is controlled as follows. track 1b
The pitch of - is extremely small, so the control for moving the needle 6 to the next track is extremely precise. - As an example, assume that the pitch of track 1b is 3.5μ, and the length of the movable part from the center of permanent stone 10 to needle 6 is 35μ.
Assuming g+n, in order to move needle 6 to the next track,
The arm 8 must be controlled to tilt approximately 0.0023 degrees. Even with such precise control, control signals engraved on the track 1b, a separately provided circuit (not shown), coils 5a to 5d, and permanent magnet 10 are required.
The feedback element is composed of movable parts including one needle 6, etc., and it is possible to achieve sufficient control even in conventional positioning, and to obtain high quality.

However, the speed forward/reverse search mode (for example, 2x speed, 16x speed, 32x speed), which is a special playback mode of a grooveless video disc player, is faster than the above-mentioned standard playback mode. Some even higher precision is required. For example, if the speed is 16x, needle 6
must be controlled so as to instantaneously jump over 15 tracks within the section indicated by an angle of 2α.In the above example, the distance of 15 tracks - 1.4 μm x 15
The needle 6 must be controlled so as to instantaneously move by -21 .mu.- and to set the needle 6 on the 16th day's track 1b with an accuracy of 1.4 .mu.-. Usually, the disc 1 and the pickup cartridge 2 have residual errors such as dimensional variations due to the manufacturing process. In the standard playback mode, this error can be almost ignored, but it becomes impossible to ignore in cases where even higher precision [11] is required, such as in the above-mentioned special playback mode such as 16x speed. In other words, in the conventional device, the needle 6 is
The movement of the needle 6 may not be sufficiently controlled, and the needle 6 may momentarily not match the track 1b, causing noise in the Ii image on the cathode ray tube.

Therefore, an object of the present invention is to provide a video disc player in which the movement of the hand 6 is sufficiently controlled even in the speed search mode.

In summary, the present invention provides a pickup cartridge for a video disc player such that the longitudinal direction of the arm of the pickup cartridge is aligned with the track direction of the disc at the point where the needle provided at the tip of the arm contacts the disc. It is something to be placed.

The above objects and other objects and effects of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 3 is a schematic top view showing a part of a disc and a pickup cartridge of a video disc player using a pickup cartridge detection method, showing an embodiment of the present invention, and the internal structure of the pickup cartridge is shown. .

In construction, disk 1 is similar to the conventional device shown in FIG. The pickup cartridge 2 is arranged in the longitudinal direction of the arm 8 at the point where the stylus 6 supported by the stylus holder provided at the tip of the arm 8 constituting the pickup cartridge 2 comes into contact with the track 1b on the disk 1. The pickup cartridge is supported and arranged by the pickup cartridge moving member 11 so that the pickup cartridge has an appropriate angle with respect to the direction of the track 1b. The structure of the pickup cartridge 2 is similar to the conventional device shown in the first all.

During operation, special attention must be paid to needle 6.
is to move diagonally across the track 1b on the disk 1. Other operations are similar to the conventional device shown in FIG.

The movement of the needle 6 diagonally across the track 1b will be explained using FIG. In IiI, point P is the position of the needle 6 before movement, point O is the center of rotation of the movable part of the pickup cartridge 2 (center of the permanent magnet 10), OP is the length of the driving part of the pickup cartridge 2, and OP is the length of the driving part of the pickup cartridge 2. C is the contact ring of track 1b' at point P, point Q is the position of needle 6 after movement, 9-1 is the pitch of track 1b, and θ is 1 piece A- shown in FIG.
The angles formed by A' and the longitudinal direction of the arm 8 are shown. The needle 6 currently located at point P on track 1b' moves to the next track 1b'' based on the control signal recorded on track 1b'. Since L>t, l0PQ-tR
Then, the needle 6 moves in the direction of the arrow PB force and moves to track 1.
#1-QPC-Otsuθ set at the position of point Q on b''
And since it can be written as QQ'-t, the needle 6 at this time is
The amount of movement PQ-t/sin θ is obtained.

FIG. 5 shows the result of calculation by substituting the actual track values t-1, 4μ- into the equation representing the amount of movement of the needle 6 shown above. The horizontal axis represents θ (unit: degrees), and the vertical axis represents needle movement amount PQ (unit: μI). As is clear from the figure, as θ approaches 90 degrees and approaches the structure of the conventional device, the amount of movement of the needle 6 approaches 1.4μ-, and as θ becomes smaller, the amount of movement of the needle 6 increases. For example, at θ-5 degrees, the amount of movement of the needle 6 is about 16 μ, which is more than 10 times that of the conventional device. If we use the 16x speed 10-bead search mode in this state, the movement of the needle 6 for 15 interlaced tracks in ms will be 16 μm x 15-240 ms.
μm, the setting accuracy of needle 6 for 16 tracks is 16μl
becomes. The ratio of setting accuracy to the moving distance of the needle 6 is the same as the conventional wheel load.

However, since the value of the setting accuracy itself is large, even if there are some errors in the disk 1 and the pickup cartridge 2, the movement of the needle 6 can be easily controlled. In other words, control inaccuracies can be compensated for by increasing the setting accuracy itself.

As described above, according to the present invention, since the movement of the needle of the pickup cartridge per track is increased, the movement of the needle can be easily controlled even in the speed search mode, and the effect is that noise is not generated in the image. is obtained.

[Brief explanation of drawings]

FIG. 1 schematically shows the upper structure of a conventional pickup cartridge detection type video disk player, showing a part of the disk and a pickup cartridge. 2nd g! 11 is a front view of the mechanical part shown in FIG. 1. FIG. 3 is a schematic top view showing a part of a disc and a pickup cartridge of a video disc player using a pickup cartridge detection method, which is an embodiment of the present invention, and the internal structure of the pickup cartridge is shown. There is. FIG. 4 is a diagram showing the movement of the stylus of the angled pickup cartridge. FIG. 5 is a graph showing the relationship between the tilt angle of the pickup cartridge and the amount of movement of the needle. In the figure, 1 is a disk, 1b is a track of the disk, 2 is a pickup cartridge, 6 is a needle of the pickup cartridge, and 8 is an arm of the pickup cartridge. Agent Makoto Kuzuno - (1 other person) 乎17 Δ Figure 3 Procedural amendment (voluntary) 5 6 Written by the Commissioner of the Japan Patent Office 1, 1-, Indication of the matter Patent application 1987-89904
No. Description. Transfer/ Title of invention
2 Video Distagray ~ To1 7゛1°i'EGt',)'R□, Detailed Description of the Invention of the Specification Subject to Amendment -, Contents of Amendment (1) Fourth Member of the Specification, Part 12 Correct the line ``in concentric circles'' to ``in a spiral.'' (2) In the specification, page 6, lines 1 to 7, "If the upper hand 6 moves in a zone other than 2α, noise will be generated on the screen every time it moves, so the hand 6 will The needle 6 is controlled to move instantaneously to the next rack when it is located in the section α.The pitch of track bWA is extremely small, so the control for moving needle 6 to the next track is extremely difficult. Even if the entire pickup cartridge 2 is moved at a position other than 2α, the needle 6 must maintain its position on the track 1b. The pitch of the track 1b is extremely small, so controlling the needle 6 when the entire pickup cartridge 2 is moved is extremely precise. ” is corrected. (3) "3.5μ plow" 2- on page 6, line 8 of the specification is corrected to "1.4μ-". Above 3-

Claims (2)

[Claims] (1) A video disc player that uses a pickup cartridge to detect and reproduce video signals recorded on tracks of a video disc, the pickup cartridge having a rotatable arm and a distal end of the arm. a stylus for detecting a video signal;
A video disc player arranged in alignment with the direction of said track. (2) The video disc player according to claim 11, wherein the video disc is of a grooveless electrostatic type.