JPS61229240A - Optical disc device - Google Patents

Abstract

PURPOSE:To improve the speed of recording/reproduction/erasure of information by moving a support means of a recording medium to apply focusing at a comparatively low frequency and moving a part of an optical system to apply focusing at a comparatively high frequency in applying focusing of a light beam spot. CONSTITUTION:An electric signal from a 4-split light sensor 9 is inputted to a focusing error detection circuit 21 and a focusing error signal is outputted from a detection circuit 21. The focusing error signal is divided into a low frequency and a high frequency component, the low frequency component is inputted to the 1st actuator drive circuit 22 and the high frequency component is inputted to the 2nd actuator drive circuit 23. The 1st drive circuit 22 is used to drive the 1st actuator 20 to reciprocate a spindle motor 15 in a direction vertical to the recording medium face, and the 2nd drive circuit 23 is used to drive the 2nd actuator to reciprocate an objective lens 4 in the optical axis direction.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention records information on a disk-shaped recording medium by irradiating a light beam spot, and/or reproduces information recorded on the disk-shaped recording medium by irradiating a light beam spot. Or it relates to an optical Dinuk device that performs erasing.

[Conventional technology]

In an optical disk playback device, which is generally well known as an optical disk device, information to be played back is recorded on a disk-shaped recording medium as information pits with a width of 1 to 2 μm and a length of 1 to 3 μm. In the disc-shaped recording medium, the bits are arranged in concentric or spiral rows to form an information track. To reproduce recorded information on a recording medium, a laser beam emitted from a Rade light source of an optical disc reproducing device is focused by an objective lens and irradiated onto the recording medium in the form of a spot. At this time, the reflected light or transmitted light from the recording medium optically changes depending on whether or not there is an information bit at the spot irradiation position on the recording medium. By detecting this change with a photodetector, a reproduced signal corresponding to the information pits can be obtained. Incidentally, since the spot irradiation position is actually scanned along the information track by rotating the disk-shaped recording medium, the recorded information is obtained as a time-series signal.

In order to increase the information recording density on the medium, the information pits on the recording medium are formed extremely small as described above, so in an optical disc playback device, the beam spot diameter on the recording medium should be irradiated with a sufficiently small beam spot. is necessary. If the recording medium is warped, a fixed optical system cannot always form an appropriate minute spot. Control for forming spots, that is, autofocusing control is necessary.

FIG. 3 is a schematic diagram of a conventional optical disc reproducing apparatus having these various autofocusing control means. In the figure, l is the radar beam generator, and the cow conductor is -
It includes a light source and a collimator lens 102. A Radhe beam emitted from a light source 101 is collimated by a collimator lens 102, passes through a half mirror 3, is focused by an objective lens 4, and is irradiated with a spot onto a disc-shaped recording medium 5. The recording medium 5 is rotated by a spindle motor 15.

The reflected light from the recording medium 5 passes through the objective lens 4 again to be collimated, is reflected by the half mirror 3, and enters the photodetector 6. The photodetector 6 is used to detect the focusing cinder state of the formation of a minute spot on the medium 5 by the objective lens 4, and the photodetector 6 for detecting this focusing error includes a convex lens 7, a cylindrical lens 8, and a cylindrical lens 4.
It includes a split optical sensor 9. The parallel light incident on the photodetector 6 enters the light having astigmatism through the convex lens 7 and the cylindrical lens 8 and the four-split optical sensor 9, where it is photoelectrically converted and output as an electrical signal. Error detection circuit lO
The detection circuit 10 outputs a 7-occurring error signal. This 7-focusing error signal is input to the actuator drive circuit 11, and the drive circuit 11 causes the actuator 12 connected to the objective lens 4 to move the objective lens 4 in the direction of its optical axis and bring it into focus. The drive is controlled to achieve this.

[Problem that the invention seeks to solve]

In recent years, however, there has been a demand for increasing the reproduction speed of recorded information in optical disc reproduction apparatuses, and for this purpose it is necessary to increase the rotational speed of the disc-shaped recording medium.

However, when the rotational speed of the recording medium is increased, the frequency of the focusing error signal appears to be higher as a whole.

For this reason, it is difficult to vibrate the actuator for focusing at a high frequency, and in particular, the resonance based on the relatively low frequency component of the focusing error signal becomes large, making it difficult to perform proper autofocusing control. For this reason, it has been difficult to improve the playback speed of recorded information in conventional disc playback devices.

The above-mentioned problems occur not only in optical disc playback devices, but also in devices that record information on a disk-shaped recording medium using other light beams, and devices that play back or erase recorded information on the recording medium. It exists in everything.

[Means for solving problems]

According to the present invention, in order to solve the problems of the prior art as described above, the present invention includes a first drive means for reciprocating the support means for the disk-shaped recording medium along the original beam irradiation direction, and a light beam irradiation optical system. a second driving means for moving at least a part of the system to reciprocate the focal position of the original beam along the irradiation direction of the light beam, and the first driving means and the second driving means move the disk An optical disc device is provided, which is characterized in that it performs focusing of original beams on a shaped recording medium.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an optical disc playback device which is an embodiment of an optical disc device according to the present invention. In this diagram, the same components as in FIG. 3 are given the same reference numerals. Therefore, the explanation will be omitted.

In this embodiment, the electrical signal from the four-split optical sensor 9 is input to a focusing error detection circuit 21, and the detection circuit 21 outputs a focusing error signal. However, in this embodiment, the focusing error signal is divided into a low frequency component and a high frequency component, the low frequency component is input to the first actuator drive circuit 22, and the high frequency component is input to the second actuator drive circuit 23. I am forced to do it. The first drive circuit 22 is used to drive the first actuator 20 for reciprocating the spindle Tanabata 15 in a direction perpendicular to the surface of the recording medium, and the second drive circuit 23 is used to drive the objective lens 4. Second actuator 1 for reciprocating movement in the optical axis direction
The second actuator 12 used to drive the second actuator 2 can be the same as in the conventional device, so its explanation will be omitted here, and the first actuator 20 will be explained.

FIG. 2 is a partial cross-sectional view showing the vicinity of the first actuator 20. In FIG. 0, reference numeral 201 indicates a bottle, and its upper surface is fixed to the bottom of the spindle motor 15.

Further, an energizing coil 203 is wound around the outer surface of the central hollow cylindrical portion of the gevin 201 in the vertical direction. A central cylindrical protrusion of the yoke 202 is fitted into the inner surface of the hollow cylindrical portion of the gopin 201 so as to be slidable in the vertical direction. A permanent magnet 204 is attached to the yoke 202. Yoke 202 is fixed to base 25 via cover 205.

By applying a drive signal current from the first drive circuit 22 to the coil 203 of the first actuator 20 as described above, the coil 203 in the magnetic circuit including the permanent magnet 204 and the yoke 202 generates an electromagnetic force. As a result, the 9&bin 201 and the spindle motor 15 are moved in the vertical direction.

The above embodiment has been explained regarding the original Dinuku regeneration device, but
The present invention relates to a device for recording information on a disk-shaped recording medium using a light beam, a device for erasing information recorded on the recording medium, and a device having the functions of recording, reproducing, and erasing, such as magneto-optical recording. It can also be applied to playback devices.

〔Effect of the invention〕

According to the present invention as described above, when focusing a light beam formed on a disk-shaped recording medium by an optical system, focusing at a relatively low frequency is performed by moving the supporting means for the recording medium. By doing so,
Focusing at a relatively high frequency can be achieved by moving at least a portion of the optical system, so even if the disk-shaped recording medium is rotated at high speed, it is possible to prevent resonance from occurring in each movable part. , Therefore, the speed of recording, reproducing, or erasing information can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the optical disc device of the present invention.
FIG. 2 is a partial cross-sectional view of the vicinity of the first actuator. FIG. 3 is a block diagram of a conventional optical disc device. 1: rateheem generator, 4: objective lens, 5: disk-shaped recording medium, 6: photodetector, 9: 4-split optical sensor,
12, 20: Actuator, 15 spindle motor, 21: Focusing error detection circuit, 22.23:
drive circuit. Agent Patent Attorney Johei Yamashita Figure 2

Claims (2)

[Claims] (1) Information is recorded on a disk-shaped recording medium by irradiating a light beam in a spot shape with an optical system, and/or information recorded on a disk-shaped recording medium by irradiating a light beam in a spot shape with an optical system. An optical disc device for reproducing a disc-shaped recording medium includes a first drive unit for reciprocating a support unit for a disc-shaped recording medium along a light beam irradiation direction, and a first driving unit for moving at least a part of a light beam irradiation optical system to perform optical reproduction. a second driving means for reciprocating a beam focusing position along the light beam irradiation direction;
An optical disc device characterized in that a driving means and a second driving means perform focusing of a light beam spot on a disc-shaped recording medium. (2) having means for detecting a focusing error, wherein a low frequency component of the focusing error signal detected by the detecting means is used as a driving signal for the first driving means, and a high frequency component of the focusing error signal; 2. The optical disc device of claim 1, wherein the component is used as a drive signal for the second drive means.