JPH0610882B2 - Information track reader - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information track reading apparatus, and more particularly, to an information track capable of performing accurate reading of information by preventing tracking in objective lens drive control and excessive control during focusing drive. It is intended to provide a reading device of.

Generally, an objective lens in an optical information track reading apparatus is configured to be freely displaceable in focusing and tracking drive directions by a plurality of leaf springs, and focusing and tracking drive control is performed so that a light spot of the objective lens is on the information track. Focusing and tracking correction are performed while driving the plurality of leaf springs so as to form an accurate image, but the light spot by the objective lens does not form an accurate image on the information track during focusing drive or tracking drive. A case occurs, and one of the causes thereof is focusing hyperactivity or tracking hyperactivity.

FIG. 1 shows a conventional information reading apparatus, which includes an objective lens 16
The lens holder 2 in which the lens frame 18 in which the
It is installed in 1. A gap is formed between the lens frame 18 and the lens holder 21, and one end of a pair of parallel first leaf springs 19 and 20 (the leaf spring 20 is shown in FIG. 2) is inserted into the gap. It is fixed with an adhesive. The first leaf springs 19 and 20 drive the objective lens 16 in a direction orthogonal to the optical axis, and the other ends of the leaf springs 19 and 20 are inserted into the grooves of the ring-shaped holding member 7, It is fixed with an adhesive or the like.

A pair of first permanent magnets 15 are arranged outside the lens holding member 21 with a gap from the member 21. A pair of first yokes 14 are provided at both ends of the pair of first permanent magnets 15 so as to sandwich the permanent magnets 15, and the objective lens 6 serves as an optical axis on the first yoke 14. A tracking coil (not shown) that drives in the orthogonal direction is wound.

In FIG. 1, reference numeral 1 denotes a cylindrical outer frame 1, on the inner surface of which a ring-shaped second permanent magnet 2 and ring-shaped second yokes 3, 4 are integrally fixed. The outer peripheral piece of the coil holding cylinder 6 having a double structure is inserted into the second yokes 3 and 4, and the focusing coil 8 is wound around the outer peripheral piece. In this case, the focusing coil 8 is provided with a gap from the second permanent magnet. A pair of second leaf springs 1 is provided at the bases of both ends of the coil holding cylinder 6 in the length direction.
One end of 9, 20 is attached, and a holding member 7 is fitted to the lower base portion 6 '. The end portion of the coil holding cylinder 6 extending upward is connected to a spacer 11 arranged in the outer frame 1 via a circular spiral leaf spring 9 held around the spacer 11.

On the other hand, the base portion 6 ′ of the coil holding cylinder 6 is connected to a spacer 12 arranged in the outer frame 1 via a circular spiral leaf spring 10 having the same configuration as the leaf spring 9. in this case,
The pair of second leaf springs 19 and 20 perform focusing error correction. Reference numeral 13 in the drawing denotes a yoke holding frame provided on the inner surface of the outer frame 1.

In the reading device configured as described above, when the focusing signal is applied to the focusing coil 8, the objective lens 16 is displaced in the optical axis direction by driving the spiral second leaf springs 9 and 10 made of an elastic material. When a tracking signal is applied to the tracking coil, the first leaf springs 19 and 20 made of an elastic material are driven and the objective lens 16 is displaced in the direction perpendicular to the optical axis.

However, since there is no means for preventing the displacement of the second springs 9 and 10 and the first springs 19 and 20 driven by the focusing signal and the tracking signal in the direction of the optical axis and the direction orthogonal thereto, The focusing or tracking error due to the excessive movement of the second leaf springs 9 and 10 or the first leaf springs 19 and 20 is not distorted.

Therefore, the present invention was developed to eliminate the drawbacks of the above-mentioned conventional reading device, and its specific configuration will be described below with reference to FIGS.

Reference numeral 30 denotes a tracking over-motion control stopper member having a diameter R1 larger than the distance l1 between the first leaf springs 19 and 20 holding the objective lens 16 and smaller than the outer diameter of the lens holder 21 made of a magnetic material. A central hole 31 is provided, and a pair of stopper pieces 32, 32 ', which are formed by bending a plate-like member and are erected on the periphery of the central hole 31, are made to face each other.

Further, as shown in FIG. 4, the stopper member 30 is a pair of left and right tracking over-motion control stoppers 3 having a structure divided into two parts from the center line between the stopper pieces 32, 32 '.
It is configured by a combination of 3, 33 '.

Further, the pair of left and right tracking overtravel control stoppers 33, 33 'are provided with semicircular arcuate portions 34, 34' constituting the central hole 31 respectively on the inner circumferences thereof and at the center of the arcuate portions 34, 34 '. A rectangular stopper piece 32, 32 'is provided with a notch in the outer peripheral direction from the portion and rises, and is integrally formed by one semicircular plate material.

Thus, the tracking overtravel control stopper member 30 having the above-described structure has the outer peripheral portions of the pair of left and right stoppers 33, 33 'of the stopper member 30 in the fixing stepped portion 35 provided in the central portion of the yoke holding frame 13. The tracking coils 17 and 17 ′ are fitted and fixed on the upper side of the yoke holding frame 13 while being sandwiched between the first yoke 14 and the first permanent magnet 15 wound with the tracking coils 17 and 17 ′. is there.

Further, parallel first leaf springs 19 and 20 for supporting the lens holding frame 21 of the objective lens 16 are inserted into the central hole 31 of the tracking overtravel control stopper member 30, and both stopper pieces 32 and 32 'are formed. As shown in FIG. 3, they are arranged so as to face each other between the left and right outer sides of the objective lens 16 and the first permanent magnet 15.

Therefore, the arcuate portions 34 and 34 'excluding the left and right stopper pieces 32 and 32' are both the front and rear side portions outside the objective lens 16 and the tracking coil 1 wound around the first yoke 14.
It is located between 7 and 17 '.

Numeral 40 is a stopper for controlling focusing overmotion, and this stopper 40, as shown in FIG.
The stopper piece 41 projecting along the outer periphery of the lower end portion 36a of the coil winding tubular portion 36 in which the focusing coil 8 is wound, and the tubular portion 36 of the coil holding cylinder 6.
A stopper plate 44 integrally fixed to the outer periphery of a disk-shaped main body 43a having a central hole 42 having a diameter larger than the outer diameter of the stopper piece 41 and smaller than the outer diameter of the stopper piece 41. Configured.

Further, FIG. 2B shows an embodiment different from the focusing over-motion control stopper 40 in FIG. 2A, and the focusing over-motion control stopper 40 in FIG. 2 is the base 6 ′ of the coil holding cylinder 6. The outer periphery of a disk-shaped main body 47a having an annular stopper piece 45 protruding along the outer circumference and a central hole 46 having a diameter larger than the outer diameter of the base 6'and smaller than the outer diameter of the stopper piece 45. The spacer 12
The stopper plate 48 is integrally fixed between a and 12b.

In the configuration of the reading device in FIGS. 2 and 3 among the above configurations, the same components as those of the device shown in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted.

In the upper track reader having the above structure,
When a focusing signal is applied to the coil 8, the objective lens 16 is displaced in the optical axis direction by driving the spiral second leaf springs 9 and 10 made of an elastic material, and when the tracking signal is applied to the coils 17 and 17 ', the elastic material is applied. The parallel first leaf springs 19 and 20 are driven to displace the objective lens 16 in the direction perpendicular to the optical axis. However, the focusing excessive movement causes the coil holding cylinder 6 to move up and down during the displacement in the optical axis direction. Accordingly, the stopper pieces 41 and 45 are replaced by the stopper plates 44 and 48.
In addition, the objective lens 16 and the lens holder 21 have the central hole 3
The tracking excessive movement is controlled by abutting against the peripheral portion of 1 to prevent further upward movement, and the tracking excessive movement is generated during the displacement of the objective lens 16 in the direction perpendicular to the optical axis direction. 32 'is the lens holder 21
It is controlled by abutting against and preventing further fluctuation in both left and right directions.

Therefore, according to the information track reading apparatus of the present invention, it is possible to control the tracking of the objective lens by the driving of the first leaf springs 19 and 20 and the second leaf springs 9 and 10 and the excessive movement during focusing driving. Therefore, it is possible to eliminate the image forming error of the light spot on the information track by the objective lens due to the excessive movement at the time of tracking drive or focusing drive, and it is possible to perform accurate reading of the information track.

[Brief description of drawings]

FIG. 1 is a partially longitudinal side view showing a conventional information track reading device, FIG. 2a is a vertical sectional view showing an information track reading device provided with a stopper mechanism of the present invention, and FIG. 2b is FIG. 2a. Is a longitudinal sectional view showing another embodiment different from the above, FIG.
FIG. 4 is a perspective view of the tracking overtravel control stopper member in FIGS. 2a and 2b. 1 ... Outer frame 2 ... Second permanent magnet 3, 4 ... Yoke 6 ... Coil holding cylinder 6 '... Base 7 ... Holding member 8 ... Focusing coil 9, 10 ... First plate Spring 11, 12 Spacer 13 Yoke holding frame 14 First yoke 15 First permanent magnet 16 Objective lens 17, 17 'Tracking coil 18 Lens frame 19, 20 ...... First leaf spring 21 ...... Lens holder 30 ...... Tracking excessive movement control stopper member 31 ...... Central hole 32, 32 '...... Stopper piece 33, 33' ...... Tracking excessive movement control stopper 34, 34 '... Arc-shaped portion 35 ... Step portion 36 ... Coil winding cylinder portion 40 ... Focusing over-motion control stopper 41, 45 ... Stopper piece 42, 46 ... Central hole 43a, 47a ... Main body 44 , 48 …… Stopper plate

Claims (1)

[Claims] 1. A lens holding member made of a magnetic material holding an objective lens, a pair of first permanent magnets arranged in the lens holding member with a gap, and a pair of first permanent magnets. A pair of first yokes arranged so as to sandwich both ends, a tracking coil wound around each of the pair of first yokes, and an optical axis of the objective lens having one end fixed to the lens holder. A pair of parallel first leaf springs extending in the direction, a pair of second leaf springs substantially arranged so as to be orthogonal to the other end of the first leaf spring, and a pair of second leaf springs. A focusing coil disposed in the vicinity of the leaf spring and the coupling portion of the first leaf spring, a second permanent magnet provided in the focusing coil with a gap, and the pair of first leaf springs. With a central hole with a diameter larger than the distance between The tracking excessive movement control stopper member is provided with a pair of stopper pieces provided so as to face the peripheral portion of the central hole by bending and standing the member. An information track reading device characterized in that the lens holder is arranged between stopper pieces.