JPS59165251A - Reader for information track - Google Patents

Abstract

PURPOSE:To obtain optimum damping operation by arranging a couple of elastic members between a lens frame for an objective and a magetic belt so that their one of terminals face the optical axis of the objective, attaching the other terminal to a holding member, and forming the base end of a coil holding cylinder to which the holding member is attached polygonally. CONSTITUTION:A circular coil holding cylinder 6 is arranged in yokes 3 and 4, and a hexagonal hole 22 is formed in at base end 6'. When a focusing signal is supplied to a coil 8, spiral springs 9 and 10 made of elastic members operate to displace the objective 16 in an optical-axis direction. The holding member 7 is fitted in said polygonal hole 22 temporarily and then detached; and another holding member 7 (having a leaf spring 19 and the objective 16 constituted) is fitted, and said replacement is repeated until an objective 16 free of buckling and resonance is selected. When the proper objective 17 is selected, the outer diameter of the holding member 7 is joined to the polygonal hole 22 with an adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for reading information by projecting a 'jtrt source spot onto a control track recorded in a spiral or concentric manner on a recording medium.

Information reading devices of this type are well known, and recording media having information tracks are, for example, called video discs.

Encoded video No. 45 and audio signals are recorded as optical information such as optical transmission characteristics, reflection characteristics, and phase characteristics. Without rotating the video disk at high speed, the laser source emitted from the laser light source is focused and projected onto the video disk to obtain optical 1-ft information Wt.

A characteristic of such a recording medium is that it is extremely bright. Therefore, the width of each information track is extremely narrow, and the intervals between successive information tracks are also extremely narrow. Therefore, the diameter of the 1tlL light spot is also significantly smaller.

In order to accurately retrieve the original information from the information track ρ, which has a narrow width and pitch, it is necessary to minimize the tracking error between the source spot and the information track, νIJ, and so on. There is peace of mind in keeping it small. For this purpose, the relative positional deviation between the reading source spot and the information track 11 to 11 is conventionally disclosed, and based on this tracking error signal, the 9-blank spot is displaced in the width direction with respect to the information track. l1ilJ control is being carried out.

There is a method of displacing the optical width of the objective lens in a direction perpendicular to the information track based on a tracking error signal using an elastic member supporting the objective lens.

In this method, the elastic member supporting the objective lens is
It is generally used in the form of a thin plate.

Examples of the drive device using an elastic member that supports the objective lens include a method using a Kamishu stone or a method using a piezoelectric element.

However, in order to improve the tracking response characteristics, it is necessary to make the device as small as possible.

In addition to such tracking errors, when directly recording a video disc, a focusing error occurs in which the original spot is not correctly focused on the information track.

In order to correct this focusing error, a focusing means for displacing the objective lens in the optical axis direction is required. This focusing means is arranged above the tracking means in terms of general Vc function.

In order to perform this focusing correction well, the tracking means must be small and have a lid. As a tracking means, there is a method of moving using a 5vL tortoise magnet as described above. Tracking +tfr j with this electromagnet
The method of performing E allows you to obtain the necessary power, and also allows you to make it smaller and lighter. However, with this 'warming magnet'
The way to do this is to make it small and payload, or to run it through a coil.
There are also disadvantages that are treated together in the relationship between the current and the shortness of the objective lens. In addition, the elastic member suffers from the drawback of buckling in relation to focusing correction and tracking correction.

In this invention, the objective lens j+ and the elastic member can be interchanged to overcome the above-mentioned drawbacks. That is, a magnetic shield is attached to the outer periphery of the lens frame with the objective lens attached and the seventh lens frame.
Attach one end of the elastic member to the lens frame and the elastic member opposite to the axis of the objective lens, attach the other end to the holding member, and attach the holding member to the coil holding member. Information that the objective lens and a pair of elastic members, which have the disadvantages of co-photography and buckling phenomena, can be freely replaced with a high-quality objective lens and a pair of elastic members by forming the proximal end of the tube into a polygonal shape. It is an object of the present invention to provide a track reading device.

The configuration of the present invention will be explained below based on the drawings.

FIG. 1 is a plan view showing the position of an elastic member supporting an objective lens in the information track reading device of the present invention, with one half taken in vertical section.

FIG. 2 is a schematic plan view showing the top surface of FIG. 1.

FIGS. 3a and 3b are a tM plane plan view and a plan view showing the bottom surface of the coil holding cylinder, showing the configuration of the fitting part that lowers the 5-dollar frame supporting the objective lens shown in FIG. .

FIG. 4 is an enlarged plan view of the elastic member supporting the objective lens shown in FIG. 1.

A ring-shaped permanent magnet 2 fixed to the outer frame IK and a ring-shaped yoke 3.4 are integrally constructed.

A circular coil holding cylinder 6 is disposed inside the yokes 3 and 4, and a hexagonal hole 22 is formed at the base end 6' of the coil holding cylinder 6, and a plate spring 19 made of an elastic member, which will be described later, is provided. 20 is fitted into the ring-shaped retaining Pf part phase 7 provided with #i, and is integrally attached with adhesive. Further, a movable coil 8 is wound around the outer periphery of the coil holding cylinder 6, and faces the circular permanent magnet 2. The upper end of this coil holding cylinder 6 is the outer frame 1
It is attached via a circular spiral spring 9 made of an elastic material that holds its periphery to a spacer 11 disposed inside and prevents focusing errors. On the outer periphery of the proximal end 6' which is fitted with the holding member 7 on its side, a spacer 12- disposed within the outer frame 1 is connected via a circular spiral spring 10 having the same shape as the above-mentioned writing spring 9. g: Shielded. A yoke holding frame 13 is attached above the spiral spring 9, and a fixed yoke 14 and a fixed (magnet 15) are attached in a pair. A coil 17 is wound around the J-ru.Objective lens 16
It is fixed integrally with the frame ls, and a small ring-shaped fitting is attached to the outer periphery. Furthermore, between the lens frame 18 and the magnetic band 21, a pair of plate blades 1 for tracking is provided.
9. A gap is provided for the 20-intrusion layer.

The leaf springs 19, 20 have one end inserted into a groove provided in the ring-shaped holding member 7, as shown in FIG. Board thickness 19.20 is board thickness or extremely thin, for example 0.02 ~
It is made of an elastic material of about 0.05.

Insert the proximal end of the elastic members 19 and 20 constructed in this way into the groove formed in the protective member 7! The tip of the IJ shield is inserted into the gap formed by the lens frame 18 equipped with the objective lens 16 and the magnetic band 21.

In the present invention configured as described above, when a focusing signal is applied to the coil 8, a coiled spring 9 made of an elastic member is activated. lO
The objective lens 16 is displaced in the direction of the original axis. Also, if you give the tracking signal to #11.17',
Due to the action of the temporary springs 19 and 20, the objective lens 16 is displaced in a direction perpendicular to the original axis. In this way, since the plate is formed by springing, it is absolutely impossible to manufacture it under the same conditions throughout the manufacturing process. 17. When the objective lens 16 was displaced in the direction perpendicular to the optical axis by the actuation line Y1 of 17' and also by the floor pillars of the blades 9 and 10, a special resonance effect occurred.This resonance In order to prevent this, damping of this vibration was performed by a magnetic material, its characteristics, temperature changes, or in order not to be redundant in the evening, it is necessary to seek the best damping effect. could not. The plates Q', l, 19, 2θ are in the focusing direction ν1, which means that the distance between the light beams of the anti-focal lens 16 is within the 1 direction [when the distance is
Buckling occurs. ν;", if the focus value is given, the compatibility with the displacement position of the objective lens 16 will be disturbed, and it will not be possible to obtain the correct a (1-nazui casting.) 7 to coil holding cylinder 6
The other holding cylinder 4A7 (plate 19.,
．． 2.0 and the objective lens 16), I repeated the exchange until I selected the lens 16 that did not cause the Shonode phenomenon or the combination of the two. By bonding and mounting the outer diameter of the holding member 7 and the polygonal hole 22, it is possible to achieve the best damping effect without causing buckling (and without causing resonance images). The present invention is not limited to the above embodiments, and the holes 22 may be arranged in a quadrangular or triangular shape, or the outer periphery of the holding member 7 may be formed in a polygonal shape.

[Brief explanation of the drawing]

Figure 1 shows the main parts of the 1-night stripping device according to the present invention; Figures 3a and b are a wT-plane plan view of the coil holding cylinder showing the gDM of the rotating part to which the elastic member supporting the objective lens shown in Figure 1 is attached, and a plan view with the lower th 71<71>; 1 is a plan view of the elastic member showing the objective lens shown in FIG. 1. l...Outer frame 2...Permanent magnet 8...Movable coil 9...Spiral spring 10...・Spiral spring 14...Fixed yoke 15-・Fixed magnet 16Φ...Objective lens 17.17'...Fixed coil 18...Mirror frame 19.e.Plate spring 20...Flat spring 21...・Magnetic band 22 fists... Hole No. 1 Figure 2 Figure 3 (CI) (b) 21 ?〇7

Claims (1)

[Claims] (1) A lens frame equipped with an objective lens, a #2 layered magnetic band fitted with a gap around the outer periphery of the lens frame, and a pair of plate-like elastic members that operate tracking and have one end inserted into the gap. An information track entertainment device comprising: a holding member to which the other end of the elastic member is attached; and a base end of a coil holding tube to which the outer periphery of the holding member is attached are formed into a polygonal hole. 12) The C-removal device for the H news track according to claim 1, characterized in that the pair of elastic members are disposed correspondingly on both sides of the optical axis of the object lens. .