JPH08329628A - Optical disk device - Google Patents

Abstract

PURPOSE: To provide an optical disk device having resistance to inclination while realizing high speed access being a characteristic of a conventional linear drive. CONSTITUTION: This device is provided with a pickup 21, a movable part 22, two axes 23, 24, a drive coil 25 and a magnet 26, and a groove 29 is formed helically on one side axis 23, and a rotary cylinder smoothly rotating along the groove 29 is provided on the bearing 28 of the movable part 22. Thus, when the device is inclined, the rotary cylinder acts as friction resistance, and the optical disk is hardly slid, and the optical disk device having resistance to inclination while realizing the high speed access and miniaturization being the characteristic of the linear drive is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device used in computer peripherals and the like.

[0002]

2. Description of the Related Art In recent years, in optical disk devices used in multimedia equipment and the like, there is a demand for maintaining the posture because of high-speed access and portability of a notebook type.
At present, there is a linear drive method as a method for realizing high-speed access, but the linear drive method is very weak against inclination and requires electric power to maintain the posture. Also,
There is a screw method as a method that is good at maintaining the posture. The conventional linear drive method and screw method will be described below.

FIG. 5 is a block diagram of a conventional linear drive type optical disk device. FIG. 6 is a relationship diagram of a force applied to a drive unit of a conventional linear drive type optical disk device, and FIG. 7 is a relationship diagram of a force exerted when the drive unit is tilted. In FIG. 5, a pickup 1 for irradiating a disc surface with a laser emitted by a light emitting element to convert the reflected light from the disc 10 into an electric signal, a movable portion 2 for moving the pickup 1, and a movable portion. It is provided with two shafts 3 and 4 used for moving the disk 2 along the disk 10 to the inner circumference or the outer circumference, and a drive coil 5 and a magnet 6 for generating a torque for moving the movable part 2.

Next, an outline of the operation will be described with reference to FIGS. 6 and 7. When the movable portion 2 is moved, the following force acts from the relationship between the magnetic flux generated by the magnet 6 and the current flowing through the drive coil 5 to move the pickup 1.

Fd = BiL (B: magnetic flux density, i: current,
L: effective length of the coil) In the linear drive, the frictional force (fm) is small because the frictional resistance between the two shafts 3 and 4 and the movable part 2 is small. Thus, it is possible to derive that the force is transmitted efficiently.

F = Fd-fm = Fd (from Fd >> fm) Next, a conventional screw system will be described. FIG. 8 is a configuration diagram of a conventional screw type optical disc device, and FIG. 9 is a relational diagram of forces applied to the drive unit. A pickup 11 for irradiating the disc surface with a laser emitted from a light emitting element and converting the reflected light from the disc 10 into an electric signal.
And a movable part 12 for moving the pickup 11.
And a drive motor 16 used to drive the movable portion 12, a screw screw 13, a shaft 14, and a bearing 15. For this reason, when the pickup 11 is moved, the screw screw 13 is driven by applying a current to the drive motor 16 and rotating the drive motor 16, so that the pickup 11 moves along the groove of the screw screw 13.

[0007]

However, in the above-mentioned conventional linear drive system, the axial force Fgsinθ generated by the own weight Fg applied to the pickup 1 when tilted by θ as shown in FIG. There is a problem that the friction force becomes larger than the friction force fm generated by the frictional resistance and starts to slide immediately. Therefore, in order to maintain the position in the inclined place, it is necessary to constantly supply the force of Fgsin θ-fm, and therefore, it is necessary to always keep the current flowing through the drive coil 5.

Further, in the conventional screw system, it is assumed that the rotation angle of the screw screw 13 is β as shown in FIG.
Assuming that the rotating force is Fd, Fd is a force Fdsinβ in the screw direction and a force Fdcosβ acting perpendicularly to the screw direction.
However, the force acts in the opposite direction to the force acting perpendicularly to the screw direction due to the action-reaction relationship, and the force of Fd (conβ) ² which is the component in the screw rotation direction acts as a frictional force. Therefore, it is possible to rotate the drive motor without torque when the angle β is closer to 90 degrees. However, when the angle β is too close to 90 degrees, the pickup movement amount becomes small and high-speed movement becomes impossible. Become.

As described above, the conventional screw system requires several tens to hundreds of tens of revolutions to move from the inner circumference to the outer circumference. Therefore, the life of the drive motor used for the screw screw (inexpensive DC (Moo etc. are often used) is becoming a problem.

Therefore, it is an object of the present invention to provide an optical disk device which is strong against inclination while realizing high-speed access, which is a characteristic of conventional linear drives.

[0011]

In order to solve the above problems, the present invention provides an optical system for irradiating a disk surface with a laser emitted by a light emitting element and converting light reflected from the disk surface into an electric signal. A pickup having a system, a movable part for moving the pickup, and two shafts for moving the movable part to an inner circumference or an outer circumference along a disc,
In an optical disk device provided with a drive coil and a magnet for generating a torque for moving the movable portion, a groove is spirally engraved on one axis, and a rotary cylinder that smoothly rotates along the groove is provided on the movable portion. When moving the pickup by mounting it on the bearing of, the relationship between the magnetic flux from the magnet and the current flowing in the drive coil (Fleming's law) creates a force that moves the movable part toward the inner or outer circumference of the disc, causing the rotating cylinder to move. While rotating along the spiral groove,
When the pickup is movable and has an inclination, the rotating cylinder serves as frictional resistance to prevent the pickup from slipping.

[0012]

With the above-described structure, the present invention realizes the high-speed access and downsizing which are the features of the linear drive,
It also becomes stronger on the slope.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a CD-ROM according to an embodiment of the present invention.
Device configuration diagram, FIG. 2 is a configuration diagram of the pickup unit, FIG.
FIG. 4 is a configuration diagram of the pickup driving unit, and FIG. 4 is a relationship diagram of forces that act when the pickup is tilted.

In FIG. 1, a pickup 2 equipped with an optical system for irradiating the disk surface with a laser emitted by a light emitting element and converting the reflected light from the disk 10 into an electric signal.
1 and a movable part 22 for moving the pickup 21.
And two shafts 23, 24 used to move the movable part 22 inward or outward along the disk 10, and a drive coil 25 and a magnet for generating a torque for moving the movable part 22. And 26 are configured. Further, a groove 29 is engraved in a spiral shape on one shaft 23, and a rotary cylinder 27 that smoothly rotates along the groove 29 is attached to the movable portion 2.
Two bearings 28 are provided.

Next, the principle of operation will be described with reference to FIG.
First, assuming that the force generated by the drive coil 25 and the magnet 26 is Fd and the frictional force generated between the movable portion 22 and the shaft 23 is fm, the force F applied to the movable portion 22 is F =
It becomes Fd-fm.

When the angle of the groove 29 is α, the force F applied to the movable portion 22 is a force Fsin acting along the groove 29.
It is divided into α and a force Fsinα that pushes vertically against the groove 29. Then, the reaction causes Fsin in the opposite direction.
α acts and F, which is the component of the moving direction to the movable part 22,
(Sin α) ² acts as a frictional force.

Therefore, letting f be the force actually applied,
It becomes possible to derive (Equation 1).

[0018]

[Equation 1]

According to (Equation 1), the pickup 2 is efficiently performed.
The movement of 1 can be realized by changing the angle of the groove 29. Also, as shown in FIG.
The frictional force fm applied to the shaft 23 and the movable portion 22, and the shaft 23
Frictional force fmw (= Fg (sin α) ² ) due to the groove 29 of
Therefore, the inclination is stronger than that of the conventional linear drive method.

[0020]

As described above, according to the present invention, it is possible to realize an optical disk device which is strong in inclination due to its simple structure while realizing high speed access and miniaturization which are the features of the linear drive.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a CD-ROM device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a pickup unit according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a pickup driving unit according to an embodiment of the present invention.

FIG. 4 is a relational diagram of forces acting when the pickup is tilted according to an embodiment of the present invention.

FIG. 5 is a block diagram of a conventional linear drive type optical disk device.

FIG. 6 is a relationship diagram of forces applied to a drive unit of a conventional linear drive type optical disc device.

FIG. 7 is a relational diagram of forces acting when a drive unit of a conventional linear drive type optical disc device is tilted.

FIG. 8 is a configuration diagram of a conventional screw type optical disc device.

FIG. 9 is a relationship diagram of forces applied to a drive unit of a conventional screw type optical disc device.

[Explanation of symbols]

 21 pickup 22 movable part 23 shaft 24 shaft 25 drive coil 26 magnet 27 rotating cylinder 28 bearing 29 groove

Claims (1)

[Claims] 1. A pickup including an optical system for irradiating a disk surface with a laser emitted by a light emitting element and converting reflected light from the disk surface into an electric signal, and a movable portion for moving the pickup. And a driving coil and a magnet that generate a torque for moving the movable part, and two shafts that move the movable part to an inner circumference or an outer circumference along the disc. The one shaft has a spiral groove. Is provided on the bearing of the movable part, and when the pickup is moved, the rotary cylinder is moved by the force generated by the magnetic flux from the magnet and the current flowing in the drive coil. The pickup moves while rotating along the groove, and when the pickup has an inclination, the rotating cylinder becomes a frictional resistance and becomes difficult to slip. Optical disk device.