JPS59201235A - Reader for information track - Google Patents

Abstract

PURPOSE:To prevent the generation of resonance and buckling phenomena by providing a couple of composite elastic members which each have a tip between a lens frame and a magneic belt and each base held by a holding member, and locking their control positions for resonance and buckling by beltlike members consisting of damping materials. CONSTITUTION:When a tracking signal is supplied to coils 17 and 17', an objective lens 16 is displaced through the operation of leaf springs 19 and 20 at right angles to an optical axis, but the resonance occurs as a result. When a focusing signal is supplied to a coil 8, the objective lens 15 is displaced along the optical axis, but buckling phenomenon occurs to leaf springs 19 and 19', 20 and 20'. For this purpose, control positions of the leaf springs 19 and 19', and 20 and 20' for the resonance and buckling are locked by the beltlike members 23 and 23' consisting of the damping materials. Thus, the resonance and buckling are prevented without spoiling characteristics of the leaf springs at a focusing and a tracking position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for reading information by projecting a reading light spot onto information tracks recorded spirally or concentrically on a recording medium.

This type of information reading device is well known, and a recording medium having an information track is called, for example, a video disc.

The encoded video signal or audio signal has optical transmission characteristics,
It is recorded as optical information such as reflection characteristics and phase characteristics. While the video disk is rotating at high speed, laser light emitted from a laser light source is focused and projected onto the video disk to read optical information.

Such recording media are characterized by extremely high information density. Therefore, the width of each information track is extremely narrow, and the spacing between successive information tracks is also extremely narrow. Therefore, the diameter of the reading light spot is also extremely small.

In order to accurately read the original information from an information trunk with such a narrow width and pitch, it is necessary to minimize the relative positional deviation between the reading light spot and the information track, that is, the tracking error. To this end, tracking control has traditionally been performed to detect the relative positional deviation between the reading light spot and the information trunk, and to displace the reading light spot in the width direction of the information trunk based on this tracking error signal. ing.

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

In this method, a thin plate-shaped elastic member is generally used to support the objective lens.

In this way, the trap objective lens is supported and the drive 'B' using an elastic member is used.
Examples of the jh device include a method using an electromagnet or a method using a piezoelectric element.

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

In addition to such tracking errors, video disk devices also suffer from focusing errors in which a light spot is not correctly focused on an information track.

In order to correct this focusing error, a 7-power sonog means for displacing the objective lens in the optical axis direction is required. This focusing means is generally arranged above the tracking means from a functional point of view.

In order to perform this focusing well, the tracking means must be small and lightweight.As a tracking means, there is a method of moving the °C using an electromagnet as described above. The method of performing tracking correction using an electromagnet is suitable for obtaining the necessary force M and is also compact and lightweight.However, this method of moving using an electromagnet is compact and lightweight, but requires the current flowing through the coil and the displacement of the objective lens. The elastic member has the disadvantage of being 4-pin in relation to the amount.Furthermore, the elastic member has the disadvantage of causing a buckling phenomenon in relation to focusing correction and tracking correction.

This invention eliminates the above drawback t#.

In other words, a magnetic band is fitted around the outer periphery of the lens frame and the 70-point lens on which the objective lens is attached, and the tips of a pair of elastic members formed compositely between the lens frame and the magnetic band are placed opposite to the optical axis of the objective lens. The other end is attached to the holding member, and a band-shaped member made of a damping material such as silicone resin or viscous rubber is inserted into the engagement groove l511 at a position to control the generation of resonance and buckling between the respective elastic members.
The object of the present invention is to provide an information track reading device which solves resonance and buckling phenomena by: '1-.

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

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

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

FIG. 3 is an enlarged plan view showing the configuration of an elastic member that supports the objective lens shown in FIG. 1.

A ring-shaped permanent magnet 2 fixed to a cylindrical outer frame 1 and ring-shaped yokes 3 and 4 are integrally constructed.

A coil holding cylinder 6 is disposed within the yoke 3.4, and its base end 61 is fitted into a ring-shaped holding member 7 to which a plate spring 19.20 made of an elastic member, which will be described later, is attached. It is fitted together. Further, a movable coil 8 is wound around the outer periphery of the coil holding cylinder 6 and faces the permanent magnet 2. At the upwardly extending end of the coil holding cylinder 6, there is a circular spiral spring 9 formed of an elastic material, whose periphery is held by a spacer 11 disposed within the outer frame 1, and which performs error correction. It is attached via. Furthermore, the base end 61 fitted with the holding member 7
A spacer 12 disposed within the outer frame 1 is attached to the outer periphery of the spring 1 through a circular spiral spring 10 having the same structure as the spiral spring 9 described above. A yoke holding frame 13 is mounted above the spiral spring 9, and a pair of fixed yokes 14 and a pair of fixed magnets 15 are mounted as a pair. The fixed yoke 14
In order to drive the objective lens 16 disposed at the center of the fixed magnet 15, a fixed coil F is wound around the fixed yoke 14, respectively. The objective lens 16 is fixed integrally with a lens frame 18, and a ring-shaped magnetic band 21 is fitted around its outer periphery. Furthermore, a gap is provided between the lens frame 18 and the magnetic band 21 in which a pair of composite plate springs 19 and 19' for tracking driving are inserted and mounted.

The leaf springs 19, 1120.20' are provided with grooves in the holding member 7 whose proximal end is formed into a ring shape as shown in Fig. .ahanel 9. 19', 20. 20J
'! It is made up of an elastic material with an extremely thin plate thickness of, for example, about 0.02 to 0.05. Parts that curve when tracking is activated on each side (knots)
The band-shaped members 23, 23j are made of a silicone resin that is not affected by temperature changes and a viscous rubber that is not affected by temperature changes and has viscous properties, such as butyl rubber.
They are each integrally constructed by sliding them together.

Elastic member 19 configured in this way. 19', 20
201 is inserted and fixed at its base end into a groove formed in the holding member 7 with a gap maintained therein, and its tip end is inserted and fixed at a gap formed by the lens frame 18 on which the objective lens 16 is attached and the magnetic band 21. ℃ inserted and fixed.

In the present invention configured in this way, when a 7-force signal is applied to the coil 8, a spiral spring 9 made of an elastic member is activated. IQ
Due to this action, the objective lens 16 is displaced in the optical axis direction IC.

Further, when a tracking signal is applied to the coil 17, 17'VC, the objective lens 16 is displaced in a direction perpendicular to the light +111 by the action of the leaf spring 19, 20. Conventionally, since a single plate spring was used, its action caused the objective lens 16 to
When the optical axis was displaced perpendicular to the optical axis, harmful resonance effects occurred. In order to prevent this resonance, damping of this vibration was performed using a magnetic body, but it was not possible to achieve the best damping effect because its characteristics were accompanied by temperature changes or because the damping effect was insufficient. Ta. Also, leaf spring 19,1.

20.2σ is the focusing force (white part) When the objective lens 16 is displaced in the optical axis direction, a buckling phenomenon (the leaf spring bends inward or outward in a dogleg shape) occurs in the conventional leaf spring configuration. . That is, the mutual characteristics between the focusing signal and the amount of displacement of the objective lens 16 are disturbed, making it impossible to read accurate information. In this way, the present invention solves the problem of resonance and buckling phenomena caused by the configuration of the leaf springs, which are drawbacks of the conventional technology. and materials that are resistant to buffering, such as linco resin or temperature characteristics (elasticity does not change even at low or high temperatures)
and a band member 23 made of a material with good damping properties, 5+11 properties, and viscosity, such as butyl rubber.
23' is attached to the parts where the occurrence of resonance and buckling are controlled.

By configuring in this way, the characteristics of the leaf springs in the 7-okashinog and tracking position movements are not impaired, and the leaf springs 19, 19', 20 and 20' do not cause buckling phenomena, nor do resonance phenomena occur. This allows for the best damping effect.

Note that the present invention is not limited to the above embodiments, and for example, a band-like member made of a mixture of silicone resin and butyl rubber may be attached.

Further, in the trap of the above embodiment, the strip members 23, 23' are attached to the side parts of the leaf springs 19, 19' and the leaf springs 20, 2d, but the band members 23, 23' are not necessarily limited to the above embodiment. −
It may be attached to the region where resonance and buckling phenomena occur between the leaf springs 20 and 20'. Furthermore, the plate springs 19.19', 20.2
It is not always necessary to attach the strip members 23 and 23' to both sides of the spring 0', and depending on the strength of the resonance or buckling phenomenon, only the leaf springs of 10,000, for example, 20 and 20' may be used.

[Brief explanation of drawings]

Fig. 1 shows the main parts of an information reading device embodying the present invention, and is a plan view with half of the side taken as a vertical section - Fig. 2 shows the top side of the M1 drawing, and Fig. 3 shows the top view of Fig. 1. FIG. 3 is an enlarged plan view of an elastic member supporting the objective lens shown in FIG. 1... Outer frame 2... Permanent magnet 8... Moving coil 9... Spiral spring 10... Spiral spring 14...Fixed yoke 15-...Fixed magnet 16 =--Objective lens 17...Fixed coil 18...- Lens frame 19.19'...・Plate spring 20.20'...Plate spring 21...Magnetic band 23.23'...Strip member No. 1 Fig. 2 Fig. 3

Claims (4)

[Claims] (1) A lens frame equipped with an objective lens, a magnetic band fitted on the outer periphery of the lens frame with a gap of 2, and a pair of plate-like elastic bands that operate tracking and have their tips inserted into the gap. An information track reading device characterized in that a member, a holding member to which a proximal end of the elastic member is attached, and a resonance control portion between each of the pair of composite elastic members are configured to engage with a band-shaped member at °C. (2) The information track reading device according to claim 1, wherein the pair of composite elastic members are disposed relative to the original axis of the objective lens. (3) The band-like member that engages with the resonance control portion between the composite elastic members is made of a resin layer or a damping material such as butyl rubber.
Device for reading information tracks as described in Section 1. (4) The strip-shaped member configured to engage with the resonance control component between the composite elastic members is configured at a side portion of the composite elastic member or between the composite elastic members. information track reader.