JPS58199445A - Reader for information track - Google Patents

Abstract

PURPOSE:To prevent resonance and buckling, by interposing two layers of silicone resin and one layer of viscous rubber between platelike elastic members for holding an objective. CONSTITUTION:The objective 16 is fitted to a mirror frame 18, which is supported by a plate spring. Silicone resin layers 22 and 22', and 23 and 23', and isobutylene-isoprene rubber layers 24 and 24' are provided between elastic members 19 and 19', and 20 and 20'. While the silicone resin layers are 4/100-8/100 thick, an isobutylene-isoprene rubber layer having 5/100-9/100 thick is suitable at the stand point of temperature characteristic and damping characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for reading information by projecting a reading light spot onto an information track 1 recorded in a spiral or concentric manner on a recording medium.

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

Do not rotate the video disk at high speed, on which encoded video signals and audio signals are recorded as optical information such as optical transmission characteristics, reflection characteristics, phase characteristics, etc. Laser light emitted from a laser light source is focused and projected onto a video disk to read optical information.

These recording media are characterized by extremely high information density.
・It is. 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 reading light spot is also extremely small. ing.

In order to accurately read the original information from an information track 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 track, and to displace the reading light spot in the width direction of the information track based on this tracking error signal. ing.

4. by an elastic member supported by the objective lens;
There is a method in which the optical axis of the objective layer 7/error signal lCf1-j is displaced by 7 degrees in a direction that is less perpendicular to the information depth 7.

In this method, the elastic member supported by the objective lens is generally thin and plate-shaped.

In this way, an elastic member supported by the objective lens is used (・
Examples of driving device means include a method using an electromagnet and 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 disc devices also suffer from focusing errors in which the light 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 δ focusing means is generally higher in function than the tracking means <k! , has been sank.

In order to perform this focusing correction 11I:jL properly,
The tracking means must be small and lightweight.

As a tracking means, it is possible to use a piezoelectric magnet as described above for movement.This method of performing tracking correction using an electromagnet can obtain the necessary force and is also suitable for being small and lightweight. However, although this method of moving using electromagnetic force is compact and lightweight, it has the disadvantage of resonance due to the relationship between the current flowing through the coil and the amount of displacement of the objective lens.
Ru. Further, the elastic member has a drawback that buckling occurs in connection with focusing correction and tracking correction.

This invention eliminates the above drawbacks.

That is, a lens frame with an objective lens mounted thereon and a magnetic band fitted around the outer periphery of the lens frame, and one end of a pair of elastic members compositely formed between the lens frame and the magnetic band are placed relative to the optical axis of the lens. The other end is attached to the barrier member, and two silicone resin layers and a viscous rubber layer are interposed between the respective elastic members. The purpose of this invention is to provide an information tracking and reading device that solves resonance and buckling phenomena.

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 supported by an objective lens in an information truck reading device embodying the present invention, taken in a half longitudinal section.
.

FIG. 2 is a schematic plan view showing the upper position of FIG. 1.

3 is an enlarged plan view of the elastic member supported by the objective lens shown in FIG. 1. FIG.

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

Inside the eyelets 3 and 4, a cylinder holding cylinder 6 is disposed, and its base end 6' is connected to a leaf spring 19 made of an elastic member, that is, an elastic material, which will be described later.・It is fitted and attached to the ring-shaped holding member 7 in which 20 is implanted. Also, the outer periphery of the oil holding cylinder 6 is movable;
The coil 8 is wound around the permanent magnet 2, which has a circular shape. The upwardly rolled end of the coil holding cylinder 6 is attached to a spacer 11 disposed within the outer frame l via a circular spiral spring 9 made of an elastic material that holds its periphery and corrects focusing errors. has been done. Further, on the outer periphery of the proximal end C which is fitted and attached to the holding member 7, a circular spiral spring 10 having the same structure as the spiral spring 9 is attached to a base plate 2 disposed within the outer frame 1. A yoke holding frame 13t is mounted above the spiral spring 9, and a fixed yoke 14 and a fixed magnet 15 are mounted as a pair. A fixed coil 17 is wound around the fixed yoke 14 to drive an objective lens 16 disposed at the center thereof. The objective lens 16 is fixed integrally with the lens frame 18, and a ring-shaped magnetic band 21 is fitted and attached to the outer periphery of the objective lens 16. Furthermore, between the lens frame 18 and the magnetic band 21,
A gap is provided in which a pair of leaf springs 19 and 20 for tracking driving are inserted and mounted.

The plate flange 19, 20 has one end inserted into a groove provided in the ring-shaped holding member 7 as shown in FIG. The plate spring 19.20 has an extremely thin plate thickness, for example 0.02~
Two pieces of elastic material of about 0.05 19°19', 20.2
0', its leaf springs 19, 19', 20
and 20' are silicon resin layers 22, 22' and 23, 23' that are not affected by temperature changes, and viscous rubber layers 24, 24' that are not affected by temperature changes and have viscous properties such as butyl rubber. They are each integrally constructed by interposing them.

The elastic members 19 and 20 configured in this manner are inserted and fixed at their proximal ends into grooves formed in the holding member 7, and at their distal ends between the lens frame 18 on which the objective lens 16 is attached and the magnetic band 21! 1IVc was inserted and fixed.

In the present invention configured as described above, when a focusing signal is applied to the coil 8, the spiral springs 9 and 10 made of elastic members are activated.
Due to this action, the objective lens 16 is displaced in the optical axis direction. Further, when a tracking signal is applied to the coil 17.1τ, the objective lens 16 is displaced in a direction perpendicular to the optical axis due to the action of the plate blades 19 and 20. In the past, since the plate was composed of a single plate having the same thickness, a harmful resonance effect occurred when the objective lens lGt was displaced in a direction perpendicular to the optical axis. In order to prevent this resonance, damping of this vibration was performed using magnetic fluid, but it was not possible to achieve the best damping effect because its characteristics were accompanied by temperature changes or because the amount of damping was insufficient. . Furthermore, when the leaf springs 19 and 20 are displaced in the focusing direction, that is, in the optical axis direction of the objective lens 16, in the conventional leaf spring configuration, a buckling phenomenon occurs (the leaf spring bends inward or outward in a dogleg shape). or occur. That is, when a focusing signal is applied, the mutual characteristics with 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 drawbacks of the conventional plate spring structure, such as resonance and buckling phenomena caused by the structure of the plate spring. Between each of the leaf springs 19', 20°20', there is a material that is strong against temperature changes and buffering and also serves as an adhesive, such as a silicone resin layer 22°22', 23.23' and temperature characteristics (elasticity even at low and high temperatures). They are each integrally constructed with intervening layers 24, 24' of material that does not change (.) and has good damping properties, elasticity, and viscosity, such as butyl rubber layers 24 and 24'.

With this configuration, it is possible to impart viscosity to the leaf spring 19, 20 without impairing the characteristics of the leaf spring during focusing and tracking positioning, and buckling phenomenon also occurs due to the reinforcement of the material layer that is not affected by buffering. Moreover, the best damping effect was possible without any resonance phenomenon occurring. It should be noted that the present invention is not limited to the above-mentioned embodiments, and for example, the amount of silicone resin and the amount of butyl rubber may be mixed in an appropriate ratio.

Note that the silicone resin layers 22.22', 23.23',
If the thickness of the butyl rubber layer 24, 24' is too small, the desired temperature characteristics cannot be obtained, and similarly, if the thickness of the butyl rubber layer 24, 24' is too small, the desired damping characteristics cannot be obtained. Therefore, sufficient consideration is required.

Now, to give a suitable example of the ratio, the thickness of the silicone resin layer is 4/100 to 8/l o o, and the thickness of the butyl rubber layer is 5/100 to 9/100. can.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the main parts of the information reading device that implemented this v4, with half of the side vertically oriented, Fig. 2 is a plan view showing the top side of Fig. 1, and Fig. 3 is the same as Fig. 1. FIG. 3 is an enlarged plan view of an elastic member supported by an objective lens. 1@■Outer frame 2...Permanent magnet 8...Movable coil 9...Spiral spring 10...Spiral spring 14@...Fixed yoke 15...Fixed magnet 16--Fist objective lens 17...・Fixed coil 18... - Lens frame 19, 19'... Leaf spring 20, 20'... Leaf spring 21... Magnetic band 22, 22', 23.23'... Silicone resin 24
, 24'...-Butyl rubber patent applicant Olympus Optical Industry Co., Ltd. -11- Figure 1 Figure 2

Claims (4)

[Claims] (1) A lens frame equipped with an objective lens, a magnetic band fitted to the outer periphery of the lens frame with a gap, and a pair of composite plate-like elastic members that operate tracking and have one end inserted into the gap. and. An information truck interposed between a holding member to which the other end of the elastic member is attached and each pair of composite elastic members, comprising two silicone resin layers and one viscous rubber layer. reader. (2) Claim 1, characterized in that the pair of composite elastic members are disposed on both sides of the optical glaze of the objective lens.
Device for reading information tracks as described in Section 1. (3) A patent claim characterized in that the silicone resin layer and the butyl rubber layer interposed between the composite elastic members are formed by mixing the amount of silicone resin and the amount of butyl rubber at a predetermined ratio. - A device for reading an information track according to item 1. − (4) 'The silicone resin layer interposed between the composite elastic members has a thickness of 4/100 to 8/1'OO, and the thickness of the butyl rubber layer has a ratio of 5/100 to 9/100. 2. An information track reading device according to claim 1.