JPS6230179Y2 - - Google Patents

Description

[Detailed explanation of the invention] (1) Technical field of the invention This invention is a digital audio disk (hereinafter referred to as
Regarding optical pickups such as DAD),
In particular, the present invention relates to an optical pickup device in which the height of the entire optical pickup device can be adjusted.

(2) Prior Art In optical pickup devices conventionally used in DADs and the like, a focus servo for aligning the focal position of an objective lens with a signal bit on a disk is usually constructed as shown in FIG. That is, as shown in FIG. 1, a ring-shaped magnet 3 is fixed to a disk-shaped lower yoke 4b having a hollow protrusion 4a at the center, and a ring-shaped magnet 3 is fixed to a lower yoke 4b having a hollow protrusion 4a at the center. An upper yoke 4d having a through hole 4e is fixed to the upper yoke 4d, a leaf spring 1 is stretched around the outer peripheral protrusion of the upper yoke 4d, and a winding frame 6 for the coil is suspended from the center of the leaf spring. The coil 5 is wound around a winding frame 6, the objective lens 2 is fixed to the coil winding frame, and the coil 5 is arranged in a through hole 4e of an upper yoke, and is composed of a magnet 3 and upper and lower yokes 4b and 4d. The optical pickup 8 is constructed by passing a current through the coil 5 within the magnetic field to change the position l between the disk 7 and the objective lens.

Here, the focus signal changes by a minute amount as shown by the arrow by the current flowing through the coil 5, but the focus signal changes by a minute amount as shown by the arrow.
When the distance l between the disk 7 and the disk 7 deviates from the optimum value by B and is far away, the situation becomes as shown in FIG. 2A, and when the distance l does not reach the optimum value by B, the situation becomes as shown in FIG. 2B.

When focus servo is applied in this condition, coil 5
Since a bias current corresponding to the deviation flows, the coil 5 generates heat, which increases the temperature of the laser (not shown) and shortens the life of the optical pickup.

(3) Purpose of the invention The present invention was developed in view of the above-mentioned drawbacks, and it is possible to adjust the height of the entire optical pickup by adding an adjustment mechanism to the optical pickup device to optimize the focus error signal. The purpose of this invention is to obtain an optical pickup device with a

(4) Structure and operation of the device The above object is to fix a bearing rotatably fitted to a shaft mounted on a base on an arm, and to fix an optical pick-up on the opposite side of the arm from the rotational fulcrum. An adjustment screw is provided in the bearing that pivots against the shaft, and by rotating the adjustment screw, the distance from the top of the base to the arm can be adjusted, and the distance between the end face of the optical pickup device and the disk can be varied. This is achieved by an optical pickup device.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 5.

FIG. 3 is a side view of the optical pickup device of the present invention, with a part of the cross section taken along a schematic line, and FIG. 4 is a plan view. The disk 7 and the end face of the optical pickup device 8 are fixed at a predetermined distance 1 from each other.

The arm 9 is mounted on a base 13 and rotates around a shaft 10, and the shaft 10 is rotatably fitted into a bearing 12 fixed to the arm.

When the optical pickup device 8 rotates about the shaft 10 from the inner circumference (outer circumference) to the outer circumference (inner circumference) of the disk 7, the arm 9 is set so as to take an appropriate offset angle θ so as to be tangential to the track of the disk 7. (See Figure 4) Furthermore, on the underside of the bearing 12 of the arm 9, a ring-shaped magnet 14 magnetized with multiple poles (two or more poles) on one side is arranged around the shaft 10. Since it is configured to attract in the direction of the base 13 made of a magnetic material (iron plate), the arm 9, bearing 12,
The optical pickup 8 is attracted downward.

Although not shown, it is also possible to arrange a coil on the base 13 to rotate the arm 9.
It is also possible to detect the rotation angle by providing a Hall element 15 or the like near the magnet. Reference numeral 11 denotes an adjustment screw screwed into the bearing, and is pivotally opposed to one end of the shaft 10.

In the above configuration, by rotating the adjustment screw 11 and adjusting the distance l between the objective lens of the optical pickup device 8 and the disk 7, the focus error output can be made as shown in FIG.

(5) Effects of the invention Since the invention is configured and operates as described above, it is possible to perform servo that does not include a bias value in the focus servo coil of an optical pickup device, which causes heat generation in the coil and an increase in the temperature of the laser. Moreover, the magnet not only biases the arm downward, but also has the function of a rotor magnet and a rotation angle detector, and its practical effects are great.

[Brief explanation of drawings]

Figure 1 is a side sectional view of a conventional optical pickup device, Figures 2A and 2B are focus error signal waveform diagrams caused by the distance between the objective lens and the disk of the optical pickup device shown in Figure 1, and Figure 3. 4 is a side sectional view of the main parts of the optical pickup device of the present invention, and FIG.
The plan view of the figure and FIG. 5 are focus signal waveform diagrams obtained by the optical pickup device of the present invention. In the figure, 1 is a leaf spring, 2 is an objective lens, 3 is a magnet, 4a is a protrusion, 4b is a disc-shaped lower yoke, 4c is an outer peripheral protrusion, 4e is a through hole, 4d is an upper yoke, and 6 is a winding frame. , 7 is a disk, 8 is an optical pickup device, 9 is an arm, 10 is a shaft, 11 is an adjustment screw, 12 is a bearing, 13 is a base, 14 is a magnet, and 15 is a Hall element.

Claims (1)

[Scope of utility model registration request] A bearing rotatably fitted to a shaft set up on a base is fixed to an arm, and an optical pick-up is fixed to the opposite side of the arm from the rotational fulcrum, and is placed in the bearing and pivotally opposed to the shaft. An optical pickup device is provided with an adjustment screw, and the distance from the base to the arm is adjusted by rotating the adjustment screw, so that the distance between the end face of the optical pickup device and the disk can be varied.