JPS63138535A - Information reproducing device - Google Patents

Abstract

PURPOSE:To improve the stability of tracking and access accuracy at the access of an optical head by providing an objective lens supporting part and an objective lens moving mechanism to a position opposed to a light source via an objective lens. CONSTITUTION:A block 25 supporting the objective lens 1 and an objective lens driver 30 moving the lens 1 are provided to the upper part of an optical system containing part 40. The driver 30 is arranged between shafts 41 and 42 and a block side 25 is arranged to a position opposed to a semiconductor laser oscillator 33 via the lens 1, that is, toward the shaft 42. Moreover, the heavy side of the driver 30 is arranged toward the shaft 42 by moving the gravity center of the entire optical head toward the direction Y between the shafts 41 and 42. Thus, the entire gravity center of the optical head, the center between the shafts 41, 42 and the moving position of the lens 1 are made coincident. Thus, the tracking stability and access accuracy at the access of the head 32 are improved and the high speed access is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an information reproducing device, such as an optical head applied to an optical disk device.

(Prior Art) Conventionally, an optical head applied to an optical disk device is movable with respect to a shaft 41, 42 provided on a drive base 47, as shown in FIGS. 5 and 6, for example. The optical system storage unit 40 is supported by an optical system storage unit 40, and an objective lens drive device (objective lens actuator) 30 is placed on the optical system storage unit 40. The objective lens driving device 30 is composed of a block 25 as an objective lens support section that supports the objective lens 1, and a movable section (not shown) as an objective lens moving mechanism that moves the objective lens 1. In addition, the optical system storage section 4
0 includes a semiconductor laser oscillator 33 as a light source, a photodetector 38 that photoelectrically converts reflected light from an optical disk (recording medium) not shown, and a condensing lens and a half prism.
An optical system including a reflecting mirror (none of which is shown) is housed.

The optical head 32 having such a configuration moves the slider arm 43 according to the direction of the magnetic field generated between the slider magnets 45 and 45 in accordance with the polarity of the current supplied to the slider coil 44. Shaft 41.
42 in the direction of arrow a in the figure, and this movement allows the optical head 32 to access the spindle motor 46.
This is done in the radial direction of an optical disk (not shown) rotated by.

However, in the conventional optical head 32, the block 25 of the objective lens driving device 30, the semiconductor laser oscillator 33 of the optical system storage section 40, the photodetector 38, etc. are provided on the shaft 41 side, so the optical The center of gravity X of the entire head is shifted toward the shaft 41 from the center Y between the shafts 41 and 42. That is, the center of gravity position X of the entire optical head, the center Y between the shafts 41 and 42, and the movement position Z of the objective lens 1 did not match.

Therefore, the center Y between the center of gravity position X and the shaft 41.42
When the optical head 32 accesses, due to the unbalance of force on the shafts 41 and 42 due to the misalignment, and the action of a moment at the position of the objective lens 1 due to the misalignment between the center of gravity position X and the movement position lZ of the objective lens 1, A rotational force is generated in the shaft 41°42 direction of the entire optical head, and the movement of the slider arm 43 becomes slow and the optical head 32
This has the disadvantage that the direction of the data is rotated, resulting in decreased tracking stability and access accuracy.

Therefore, the center of gravity position X of the entire optical head and the shaft 4
1,421 I! A weight (
It has been devised to provide a balancer. However,
When extra items are attached, there is a problem in that they impede high-speed access of the optical head 32.

(Problems to be Solved by the Invention) In this invention, the center of gravity of the entire optical head does not match the center between the shafts and the moving position of the objective lens. Eliminate the disadvantages of slow movement or rotation of the direction of the optical head, reducing tracking stability and access accuracy, and improve the center of gravity of the entire optical head and the center between the shaft and the movement position of the objective lens. of,
Can be matched without installing extra items,
An object of the present invention is to provide an information reproducing device that improves tracking stability and access accuracy when accessing an optical head, and can perform high-speed access.

[Structure of the Invention] (Means for Solving Problems) An information reproducing device of the present invention includes: a light source that generates a light beam; an objective lens that focuses the light beam generated from the light source on a recording medium; An objective lens support part that is provided at a position facing the light source through the objective lens and supports the objective lens, and an objective lens moving mechanism that moves the objective lens with respect to the recording medium. It is.

(Function) According to the present invention, the objective lens support portion and the light source are arranged at positions facing each other with the objective lens interposed therebetween.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a schematic configuration of an optical head to which the present invention is applied. That is, the optical disc (recording medium) 3
1 is adapted to be rotated by a spindle motor (not shown) at a constant linear velocity with respect to an optical head, which will be described later. The optical disk 31 has a circular substrate made of glass or plastic, for example, and the surface of the substrate is coated with a donut-shaped metal film layer such as tellurium or bismuth.

Information is recorded on the back side of the optical disc 31.

An optical head 32 for reproduction is provided. This optical head 32 includes a semiconductor laser oscillator 33 as a light source, a half prism 34, a condensing lens 35, a reflecting mirror 36, an objective lens 1, a cylindrical lens 37, and a photodetector 38 for detecting tracking deviation and force focusing blur. It is configured.

The objective lens 1 is driven by an objective lens driving device (objective lens actuator) 30 shown in FIG. That is, the objective lens 1 is attached to the holder 2
A focus coil (drive coil in the focus direction) 3 is wound around the holder 2, and two pairs of track coils (drive coils in the tracking direction) 4 are mounted on both sides of the holder 2. An integral movable part is formed. In addition, through holes (not shown) are formed in both sides of the holding body 2 perpendicular to both side surfaces, and four wires 20 made of non-metallic mH or carbon fiber, for example, are inserted into the through holes. The movable part is configured to be supported by having the other end bored in a block (objective lens support part) 25 mounted on the base 10. Therefore, the objective lens drive device 30 is configured such that the weight is placed closer to the block 25 than to the movable part.

Further, on the base 10, yokes 11a, 11b, 11C made of a magnetic material (for example, Fe) are erected and integrally formed, and each of the inner walls of the yokes 11a, 11b has a pair of The magnets 12a and 12b are mounted facing each other, while the focus coil 3 and track coil 4 are wound around the outer periphery of the yoke 11C to form a magnetic circuit. Therefore, when current flows through the focus coil 3 and the track coil 4, the movable part bends the four wires 20 due to the force of the focus coil 3 acting in the focusing direction and the force of the track coil 4 acting in the tracking direction. It exhibits a phenomenon in which it is moved by At this time, the movement of the movable part is suppressed by silicon rubber in a vibrator (not shown) into which the wire 20 provided on the block 25 is inserted, and when this vibration system resonates, the imaging is damped. ing.

On the other hand, 13 is a printed circuit board attached to the outer wall surface of the yoke 11a set up on the base 10, and the pattern of this printed circuit board 13 includes lead wires 3L leading out from both ends of the focus coil 3, and a track coil 4. Lead wires 4L led out from both ends of the
are soldered and electrically connected. Therefore, when a current is supplied to the focus coil 3 or the track coil 4, the magnet 12a,
Due to electromagnetic interaction with the lens 12b, the objective lens 1 and the holder 2 can be moved integrally in the focus direction or the track direction.

FIG. 2 shows a drive device to which the information reproducing device of the present invention is applied. That is, the drive path 47
Shafts 41 and 42 are provided in parallel to each other, and the optical system storage section 40 is movably supported on the shafts 41 and 42 by support sections 41a and 42a. This optical system housing section 40 includes a semiconductor laser oscillator 33 as a light source, a photodetector 38 that photoelectrically converts reflected light from an optical disk (recording medium) not shown, and a condensing lens, a half prism, and a reflecting mirror (all of which are (not shown), etc. is housed therein.

Furthermore, as shown in FIG. An objective lens drive device (objective lens actuator) 30 is provided, which includes a block 25 as an objective lens support section that supports the objective lens 1 and a movable section (not shown) as an objective lens moving mechanism that moves the objective lens 1. There is. In this objective lens driving device 30, the objective lens 1 is arranged at the center Y between the shafts 41 and 42,
The block 25 side is arranged at a position facing the semiconductor laser oscillator 33 via the objective lens 1, that is, on the shaft 42 side. That is, the objective lens 1 is arranged at the center Y between the shafts 41 and 42 so that the objective lens 1 is moved on the center Y axis between the shafts 41 and 42, and furthermore, the center of gravity aX of the entire optical head is located at the center Y axis between the shafts 41 and 42. .42 so that the center is moved in the Y direction between
The heavier side of the objective lens drive device [30 is placed on the shaft 42 side. As a result, as shown in Fig. 2, the center of gravity of the entire optical head is aligned! Center Y between fX and shaft 41.42
and the displacement position @Z of the objective lens 1 are made to match.

On the other hand, the drive base 47 is provided with a yoke 48 of a slider portion. This yoke 48 has a first yoke provided parallel to the shaft 41,42. Second. Third leg portions 48a, 48b, 48c, and these leg portions 48a, 48
b, 48c, respectively. Third leg 48a, 4
Magnets 45 and 45 for the slider are respectively attached to 8c, and the slider coil 44 is attached to the second leg 48b.
The arm 43 for the slider is fixedly attached. The other end of this arm 43 is attached to one end of the optical system storage section 40.

The optical head 32 having such a configuration has a shaft by moving the slider arm 43 according to the direction of the magnetic field generated between the slider magnets 45 and 45 in accordance with the polarity of the current supplied to the slider coil 44. 41.4
2, in the direction of arrow a in the figure, that is, the objective lens 1 is moved through the center Y between the shafts 41 and 42 (movement position [2), and this movement causes the access of the optical head 32 to be rotated by the spindle motor 46. This is done in the radial direction of an optical disc (not shown).

As described above, the block side is disposed at a position facing the semiconductor laser oscillator through the objective lens, and the objective lens is disposed at the center of each shaft. This makes it possible to match the center between the shafts with the moving position of the objective lens, and also allows the center of gravity of the entire optical head to substantially match the center between the shafts. Therefore, it is possible to eliminate the unbalance of forces applied to each shaft, and also to prevent a moment from being generated at the position of the objective lens. It is possible to eliminate drawbacks such as deterioration in the movement of the slider arm and rotation of the optical head.

In other words, by matching the position of the center of gravity of the optical head with the center position between the shafts, the frictional force on each shaft becomes equal, and by matching the position of the center of gravity of the optical head with the movement position of the objective lens, the position of the objective lens relative to the center of gravity becomes equal. Moment no longer works. Therefore, the stability of tracking during access increases, and it becomes possible to improve the accuracy of access.

In addition, it is possible to match the center of gravity of the optical head, the center position between the shafts, and the moving position of the objective lens without attaching any parts to the optical head that add weight to the optical head. This prevents changes in the weight of the optical head, that is, increases in weight, which prevents high-speed access.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to match the center of gravity of the entire optical head with the center between the shafts and the moving position of the objective lens without attaching any extra parts. Therefore, it is possible to provide an information reproducing apparatus that can improve tracking stability and access accuracy when accessing an optical head, and can perform high-speed access.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing an embodiment of an information reproducing device of the present invention, FIG. 2 is a plan view schematically showing the configuration of a drive device to which the present invention is applied, and FIG. 3 is an optical head 4 is a schematic diagram of the objective lens drive device, FIG. 5 is a perspective view schematically showing the configuration of a conventional optical head, and FIG. 6 is a schematic diagram of the configuration of a conventional drive device. FIG. DESCRIPTION OF SYMBOLS 1... Objective lens, 25... Block (objective lens support part), 3o... Objective lens drive device, 31...
Optical disc (recording medium), 32... optical head, 33
... Semiconductor laser oscillator (light source), 34... Half prism (optical system), 38... Photodetector, 40...
Optical system storage section, 41.42...Shaft, 43...
Arm for slider. Applicant's agent Patent attorney Takeshi Suzue Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) a light source that generates a light beam; an objective lens that focuses the light beam generated from the light source onto a recording medium; An information reproducing apparatus comprising: an objective lens support section that supports the objective lens; and an objective lens moving mechanism that moves the objective lens relative to the recording medium. (2) The objective lens support part and the objective lens movable mechanism are
A holder to which the objective lens is fixed, a focus coil wound around the holder, two pairs of track coils provided on both sides of the holder, and both sides perpendicular to both sides of the holder. A patent claim comprising four wires that are inserted into through holes drilled in the section, and a block that supports the objective lens by having the other ends of these wires drilled therein. The information reproducing device according to item 1. (3) The information reproducing device according to claim 1, wherein the objective lens is disposed at the center of gravity.