JPH05274821A - Carriage guide mechanism - Google Patents

Abstract

PURPOSE:To obtain the carriage guide mechanism movable for high-speed access by the construction to rotate a carriage guide shaft at all times during the tracking or accessing action of a carriage. CONSTITUTION:The displacement X of the carriage 101 changes smoothly (curve 204) and there is no stop region right after the change of motor thrust F when the stick slip between the carriage and a guide shaft 104 is eliminated. The reason thereof lies in that the carriage 101 and the guide shaft 104 are always in the relatively moving state. The relative motion of the contact point 102a of the bearing part 102 of the carriage 101 on the developed plane 105 of the outer peripheral cylindrical surface of the guide shaft 104, shown in Fig., is equiv. to the standstill of the developed plane 105 and the constant movement of the contact point 102a in a beta direction. The presence of a fluctuation in the thrust in the linear motor of tracking servo entails the reciprocating motion of the contact point 102a in the axial direction alpha of the guide shaft 104. The movement in the beta direction continues and the combined relative speed of the directions alpha, beta is not zero. Then, the static friction state does not exist and the smooth traveling characteristic free from the stick slip is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carriage guide mechanism in an optical disk device which is a storage device that can be accessed at high speed.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, an optical disk device of this type has two parallel guide shafts 304 mounted on a carriage 30.
6 pieces arranged in the access direction of 1 and rolling in contact with the guide shaft 304 (only 6 pieces are visible in FIG. 8, but 6 pieces are required)
In general, the ball bearing 300 was mounted on the carriage 301 and guided movably only in the access direction with extremely small running resistance while restraining the three degrees of freedom of pitching / rolling / yawing.
Further, in a low-speed access digital audio disc (compact disc) device or the like, a sliding bearing is used as a guide mechanism to reduce the cost.

[0003]

However, the ball bearing type carriage guide mechanism as shown in FIG. 8 has extremely good running resistance and excellent controllability during the tracking operation or the access operation, but the expensive ball bearing 300. It was impossible to commercialize the optical disk device at a popular price, because 6 of them were used and the assembling accuracy had to be controlled on the μ order. Further, since the mass of six bearings is large and the volume is large, the volume and mass of the movable portion including the carriage 301 are increased, which is an obstacle to high-speed access.

On the other hand, in the conventional type sliding bearing used in the compact disc device or the like, the guide mechanism can be constructed at 1/10 or less of the cost in comparison with the ball bearing type, but static friction and Since there is a non-linearity of running resistance (hysteresis characteristic due to stick-slip) due to repetition with dynamic friction and a large average running resistance, it can be applied to storage devices such as magneto-optical disk devices that require high-speed servo control. There wasn't.

[0005]

The structure of the present invention for solving the above-mentioned problems is as follows: (1) In an optical disk device of a type in which a carriage equipped with an objective lens is transferred by a linear motor, during tracking or access operation of the carriage, The guide shaft that supports the carriage is always rotated. (2) A carriage equipped with an objective lens is moved by a linear motor and an optical disk is rotated by a spindle motor. It is characterized in that the guide shaft supporting the shaft has a structure in which a driving force is transmitted from a spindle motor to rotate during tracking or access operation of the carriage.

[0006]

According to the above structure, the guide shaft supporting the carriage is always rotated during the tracking or access operation of the carriage, so that the contact point between the guide shaft and the carriage is stationary. The hysteresis characteristics due to the stick-slip phenomenon peculiar to sliding bearings do not adversely affect the tracking servo system.

[0007]

【Example】

(Embodiment 1) FIG. 1 shows an optical disk device including a carriage guide mechanism in an embodiment of the present invention. 2, FIG. 3 (a), FIG. 3 (b), and FIG. 3 (c) are sectional views corresponding to the sections AA, BB, CC, and DD of FIG. 1, respectively. Reference numeral 10 is an optical disk, 12 is a spindle motor for rotating the optical disk 10, and 101 is a carriage. Boss portions 102 serving as bearings are formed on both sides of the carriage 101. The boss portion 102 is inserted through the two left and right guide shafts 104 with a very small gap to form a carriage guide mechanism. A movable coil 110 is fixed to the carriage 101, and an internal yoke 111 penetrates a space inside the winding of the movable coil 110 with a gap. Therefore, the carriage 101 is held integrally with the movable coil 110 so as to be movable only in the longitudinal direction of the outer yoke 112 (direction of arrow α in FIG. 1).

The outer yoke 112 is arranged parallel to the inner yoke 111 and on both sides of the movable coil 110, and in the space sandwiched between them, the permanent magnet 113 fixed to the outer yoke 112 and the winding of the movable coil 110 described above. Are placed. The movable coil 110, the outer yoke 112, the inner yoke 111, and the permanent magnet 113 constitute a so-called voice coil type linear motor. Further, the linear motor, the carriage 101, and a focusing mechanism described later together form a movable head.

As shown in FIG. 2, the carriage 101 supports a lens holder 15 via two parallel leaf springs 14, and the objective lens 6 is mounted on the upper surface of the lens holder 15. Therefore, the objective lens 6 and the lens holder 15 can be slightly moved along the bending direction of the leaf spring 14 in a substantially axial direction of the objective lens 6 (that is, in a direction substantially orthogonal to the plane of the optical disc 10) with a predetermined restoring force. Supported by. As shown in FIG. 3B, the lens drive coil 18 is fixed to both side surfaces of the lens holder 15, and the outer yoke 112, the inner yoke 111, and the permanent magnet 113 constitute a so-called voice coil type focusing mechanism. .. The shape of the lens holder 15 is a substantially rectangular frame structure that is substantially the same as the cross-sectional shape of the movable coil 2 (see FIGS. 3B and 3C).

Reference numeral 7 shown in FIG. 2 is a flip-up prism,
It is a total reflection prism fixed on the carriage 101. The reflected light from the recording surface of the optical disc 10 is picked up by the objective lens 6, and the light flux thereof is bent by the flip-up prism 7 in parallel with the moving direction (α direction) of the carriage 101 to become a light flux 8. On the contrary, when converging the incident light on the recording surface, the same path is followed in reverse.

Although detailed description is omitted in this embodiment, an optical system including a laser light source and a signal detector, a mechanism for performing precise tracking (generally a galvanomirror is used), etc. are separated from the carriage 101. It is fixed to the main frame 20 of the main body of the optical disk device and forms a fixed optical system 21. The fixed optical system 21 is optically coupled to the flip-up prism 7 and the objective lens 6 on the carriage 101 by the light beam 8.

As shown in FIGS. 1 and 3A, both ends of two left and right guide shafts 104 are rotatably supported by the main frame 20, and each of the guide shafts 104 is fixed to two. Gear 120, timing belt 121
Rotate at the same time through. These guide shafts 104 are
The driving force of the small-sized motor 122 is transmitted by another timing belt 123 to rotate in the direction of arrow β.

Next, the running characteristics of the carriage guide mechanism constructed as described above will be described with reference to FIGS. FIG. 4A shows the traveling characteristics of the carriage 101 when the guide shaft 104 is not rotated. The upper curve 201 in the figure represents the thrust F of the linear motor that drives the carriage 101, and represents the thrust fluctuation of the linear motor when tracking eccentricity and undulation during rotation of the track groove of the optical disc 10 by tracking servo control. The lower curve 202 in the figure shows the actual displacement X of the carriage 101.

As shown, the displacement X does not change smoothly,
The stop region 203 exists immediately after the direction of the thrust F changes. This phenomenon is caused by the stick slip between the carriage 101 and the guide shaft 104. As shown in FIG. 4B, the weight W of the carriage 101 acts on the shaft 104 in a stationary state, and friction described by μ × W (μ is a friction coefficient) acts. However, μ is the carriage 101 and the guide shaft 1.
There is a relationship of μh >> μm between the value μh when 04 is relatively stationary and the value μm when relatively moving. Further, the thrust F of the linear motor becomes smaller and the relative speed becomes slower, and the frictional force μh × W becomes
When the motion inertial force of 01 and the linear motor thrust F are overcome, the carriage 101 is stopped. When the thrust F of the linear motor increases again and the frictional force μh × W is overcome, the carriage 101 starts moving again.

This mechanism is the so-called stick-slip phenomenon, and as shown in FIG. 4A, the stop region 203 exists immediately after the direction of the thrust F changes, and it can smoothly follow the fluctuation of the thrust F. Instead, the operating characteristics have hysteresis. If the tracking servo system has a hysteresis characteristic due to the stick-slip phenomenon, it cannot sufficiently follow the eccentricity and waviness of the track groove of the optical disc 10 during rotation, and a practically problematic level of servo residual error occurs, resulting in poor signal reproduction characteristics. Extremely worse.

FIG. 5A shows the traveling characteristics of the carriage 101 when the guide shaft 104 is rotating. The upper curve 201 in the figure represents the thrust F of the linear motor that drives the carriage 101, and represents the thrust fluctuation of the linear motor when tracking eccentricity and undulation during rotation of the track groove of the optical disc 10 by tracking servo control. In this case,
(A) The displacement X changes smoothly as shown by the lower curve 204, and there is almost no stop region immediately after the direction of the thrust F changes. This is the carriage 101 and the guide shaft 104.
Is always in relative motion, and there is no stick slip between the carriage 101 and the guide shaft 104. This will be described in detail with reference to FIG. The figure shows a plane 1 in which the outer peripheral cylindrical surface of the guide shaft 104 is expanded
05 shows the relative movement of the contact point 102a of the bearing portion 102 of the carriage 101 on 05, and when viewed from the viewpoint of rotating together with the guide shaft 104 that rotates in order to make it easier to understand, the outer peripheral cylinder of the guide shaft 104 Surface development plane 10
5 is stationary, the contact point 102 of the carriage bearing portion 102
It is equivalent to that a always moves with a velocity in the β direction. Here, when there is a thrust force variation of the linear motor when the eccentricity and the waviness during the rotation of the track groove of the optical disk 10 are tracked by the tracking servo control, the contact point 102a becomes as shown in FIG.
As shown in (b), the α direction (the axial direction of the guide shaft 104)
It involves a reciprocating motion. Since the movement in the β direction continues,
The relative speed that combines the α and β directions never becomes 0 (zero). Therefore, there is no static friction state, and smooth running characteristics without stick slip can be obtained as described above.

In the present embodiment, the inventors have specifically made an experiment by variably setting the rotation speed of the guide shaft 104. However, the rotation frequency of the optical disk 10 and its harmonic frequency depend on the warp of the guide shaft. A slight vertical movement of the carriage 101 may adversely affect the servo characteristics, and if the rotation speed is intentionally deviated from the rotation speed of the optical disk 10, a sufficient effect can be obtained in the range of several tens to several hundreds rpm. Was given.

Further, in this embodiment, the small motor 122 is used as the drive source of the guide shaft 104, but a small DC brush used in a toy or the like can be used. Such a motor can be obtained at a cost of about one ball bearing, and the transmission mechanism is composed of inexpensive parts. Therefore, the entire optical disc apparatus is more advantageous than the case where the conventional carriage guide mechanism shown in FIG. 8 is used. Can be constructed at low cost. Further, since the movable head including the carriage 101 does not require the volume of the six ball bearings 300 used in the conventional technique, it is compact and its mass is reduced.

By the way, although the guide shaft 104 is driven via the timing belts 121 and 123 in this embodiment, the present invention is not limited to this, and a transmission mechanism using a gear train or the like may be used. Further, although the boss portion 102 is slid directly on the left and right two guide shafts 104, lubricating oil may be injected or a separate slide bearing member may be interposed here, which is within the scope of the technical idea of the present invention. It is in.

(Embodiment 2) FIG. 6 shows an optical disk device including a carriage guide mechanism in another embodiment of the present invention, and FIG. 7 is a sectional view corresponding to a section EE in FIG.
Both ends of the left and right two guide shafts 104 are connected to the main frame 2
The guide shafts 104 are rotatably supported by 0, and the respective guide shafts 104 simultaneously rotate via the gear 120 and the timing belt 121. These guide shafts 104 rotate by receiving a part of the driving force of the spindle motor 12 that rotates the optical disc 10. That is, the worm portion 125 is formed on the outer periphery of the rotor of the spindle motor 12, and the worm portion 125 and the guide shaft 1
The worm gear 126 fixed to one of the gears 04 is power-coupled with a large reduction ratio,
0, the other guide shaft 1 via the timing belt 121
04 also rotates. Therefore, the two guide shafts 104 are always rotating during the rotation of the optical disk 10, and the optical disk 10 is naturally rotating during the tracking operation / access operation of the carriage 101, and therefore, the first embodiment has been described. As described above, smooth carriage running characteristics without stick-slip can be obtained. Further, this embodiment is characterized in that the special motor 122 for driving the guide shaft, which is used in the first embodiment, is not required.

In this embodiment, the rotation speed of the spindle motor 12 is assumed to be about 3000 rpm. Therefore, in order to keep the rotation speed of the guide shaft 104 at the same level as in the first embodiment, the reduction ratio of the transmission mechanism from the spindle motor 12 to the guide shaft 104 may be set to about 1/10.

In this embodiment, each guide shaft 1
Although 04 is driven via the timing belt 121, the present invention is not limited to this, and a transmission mechanism using a gear train or the like may be used.

Although the worm gear 125 transmits power from the spindle motor 12 to the guide shaft 104, it can be replaced with another transmission mechanism.

[0024]

As described above, according to the present invention, since the guide shaft that supports the carriage constantly rotates during the tracking or access operation of the carriage, the stick-slip phenomenon peculiar to the sliding bearing is generated. The hysteresis characteristic due to does not adversely affect the tracking servo system. Further, it is not necessary to use many expensive ball bearings, and the volume and mass for this can be reduced.
Therefore, it is possible to realize an optimal carriage guide mechanism for an optical disc device that can be accessed at high speed by an inexpensive means.
It has great industrial significance.

[Brief description of drawings]

FIG. 1 is a plan view showing an optical disk device including a carriage guide mechanism in an embodiment of the present invention.

FIG. 2 is a sectional view corresponding to AA in FIG.

3A to 3C are respectively BB and C of FIG.
It is sectional drawing corresponding to -C and DD.

4A and 4B are explanatory diagrams showing the traveling characteristics of the carriage 101 when the guide shaft 104 is not rotated.

5A and 5B are explanatory diagrams showing traveling characteristics of the carriage 101 when the guide shaft 104 is rotating.

FIG. 6 is a plan view showing an optical disk device including a carriage guide mechanism according to another embodiment of the present invention.

FIG. 7 is a sectional view corresponding to section EE in FIG.

FIG. 8 is a sectional view showing a carriage guide mechanism according to a conventional technique.

[Explanation of symbols]

 10 Optical Disc 12 Spindle Motor 20 Main Frame 101 Carriage 104 Guide Shaft 120 Gears 121, 123 Timing Belt 122 Small Motor 126 Worm Gear

Claims (2)

[Claims] 1. An optical disk device of a type in which a carriage carrying an objective lens is moved by a linear motor, and a guide shaft that supports the carriage is always rotated during tracking or access operation of the carriage. Carriage guide mechanism that is characterized. 2. In an optical disk device of a type in which a carriage equipped with an objective lens is transferred by a linear motor and an optical disk is rotated by a spindle motor, a guide shaft for supporting the carriage is in tracking or access operation of the carriage. A carriage guide mechanism having a structure in which a driving force is transmitted from the spindle motor to rotate.