KR100234333B1 - Optical pickup apparatus - Google Patents

Abstract

Disclosed is an optical pickup apparatus for forming an optical spot on a plurality of tracks of an optical disc at the same time. The optical pickup apparatus includes a light source; Grating for diffraction transmission of incident light into a plurality of lights; Optical path converting means for converting the advancing path of the incident light; An objective lens for focusing the light incident from the light source and condensing on the recording surface of the optical disk; An optical pickup apparatus comprising a photodetector that is reflected from an optical disc and receives light incident through an objective lens and optical path converting means, wherein the photodetector is diffracted in grating and reflected at each track position of the optical disc. Each of the photodetectors is configured to receive information reflected at each track position adjacent to each other of the optical disk to read information on at least two tracks of the optical disk.

Description

Optical pickup apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup apparatus, and more particularly, to an optical pickup apparatus capable of simultaneously reading information on a plurality of tracks of an optical disc.

In general, an optical pickup apparatus is a device for recording / reproducing information in a non-contact manner to a recording surface of an optical disk.

1 is a block diagram showing an optical arrangement of a conventional optical pickup device.

As shown, the optical pickup device is roughly composed of a light source 10, an objective lens 25, a beam splitter 23, and a photodetector 29. The light source 10 is implemented with a semiconductor laser and emits laser light of a predetermined wavelength. The objective lens 25 converges the light incident from the light source 10 to be formed on the recording surface of the optical disc 1. The beam splitter 23 is located on the optical path between the light source 10 and the objective lens 25 and prevents the light reflected from the optical disk 1 from being reincident to the light source 10. That is, the beam splitter 23 reflects most of the light incident from the light source 10 and directs the light incident from the objective lens 25 toward the photodetector 29. The photodetector 29 receives a beam reflected from the recording surface of the optical disc 1 to detect a radio frequency (RF) information signal and an error signal. The photodetector 29 is composed of a plurality of dividers to receive light independently.

The optical pickup apparatus further includes a grating 21, a collimating lens (not shown), and an astigmatism lens 27. The grating 21 and the collimating lens are disposed on an optical path between the light source 10 and the optical disk 1, and the grating 21 detects a track error signal by the three-beam method in the photodetector 29. Diffuse the incident beam into a zero-order diffraction beam, a ± first-order diffraction beam, ..., and so on. The collimating lens converts an incident divergence beam into a parallel beam. The astigmatism lens 27 is disposed on the optical path between the beam splitter 23 and the photodetector 29. The astigmatism lens 27 is a semi-cylindrical lens, and the distance between the objective lens 25 and the optical disk 1 is In the case of on focus, a circular beam is made to the photodetector 29, and an elliptical beam is made to the optical disc 1.

The optical pickup device provided as described above performs recording / reproducing of information while following one track irradiated from the light source 10, that is, the main beam spirally formed on the recording surface of the optical disc 1, and performing the grating 21 Track error signal is detected by using the? Therefore, the optical pickup device mentioned above has a limitation in increasing the information processing speed because the performance of the optical disk player, that is, the information processing speed, depends greatly on the rotation speed of the spindle motor 5 which rotates the optical disk 1. .

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problems, and an optical pick-up in which each of a plurality of lights irradiated to a recording medium can be used for information signal detection so as to greatly increase the information processing speed of an optical disc player. The purpose is to provide a device.

1 is a block diagram showing an optical arrangement of a general optical pickup device.

Figure 2 is a schematic view showing the light bound to the optical disk of the optical pickup apparatus according to the present invention.

3 is a schematic view showing a photodetector according to the present invention.

<Explanation of symbols for main parts of drawing>

1.optical disk 10 ... light source 21 ... grading

23.Optical path changing means 25.Objective lens 27.Astigmatism lens

29.Photodetector

An optical pickup apparatus according to the present invention for achieving the above object, the light source; Grating for diffracting the incident light from the light source into zero order diffraction light, +1 order diffraction light, and -1 order diffraction light; Optical path converting means for converting a traveling path of the zeroth order and ± first order diffracted light; An objective lens for concentrating zeroth order and ± first order diffracted light incident from the light source, so that each of the diffracted light is formed on different tracks of the optical disk recording surface; Four split plates (G, H, I, J) for independently photoelectric conversion of the received light, and receiving the + first order diffracted light reflected from the optical disk to the track error signal and the first track of the optical disk A first photodetector for detecting information about the apparatus; Four divided plates A, B, C, and D for photoelectric conversion independently of the received light, and receive the zero-order diffracted light reflected from the optical disk to provide a focus error signal and a second track of the optical disk. A second photodetector for detecting information; Comprising four split plates (K, L, M, N) for independently photoelectric conversion of the received light, receives the -first diffraction light reflected from the optical disk and detects a track error signal with the first photodetector And a third photodetector for detecting information on the third track of the optical disk, wherein the information on three tracks of the optical disk can be read simultaneously.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention;

The optical arrangement of the optical pickup apparatus according to the embodiment of the present invention is substantially as shown in FIG. 1, that is, the light source 10 generating and emitting laser light and the light emitted from the light source 10 are multi-lighted. Grating 21 for diffraction transmission, optical path converting means 23 for converting an advancing path of incident light, an objective lens 25 for condensing incident light to be formed on a recording surface of the optical disk 1, and the optical disk ( And a photodetector 29 which is reflected at 1) and receives the light via the objective lens 25 and the optical path converting means 23.

The grating 21 is disposed on the optical path between the light source 10 and the optical path converting means 23, and the light incident from the light source is 0 order light, ± 1 order light, ± 2 order light, ... Diffraction transmission. Here, it is a feature of the present invention to use the diffracted 0th order light as well as the ± 1st order light as the main beams.

The light path converting means 23 directs the light incident from the light source 10 toward the optical disk 1, and the light incident from the optical disk 1 toward the photodetector 29. Convert the path. As shown in the figure, the optical path converting means 23 may employ a beam splitter for dividing incident light by a predetermined light quantity ratio and transmitting and reflecting the light. In addition, a hologram element for transmitting light incident in one direction and diffracting the light incident in another direction and a beam splitter for transmitting or reflecting incident light according to the polarization direction may be employed.

Each of the light emitted from the light source 10 by the grating 21 and diffracted is bound to a track at another position of the optical disc 1 via the beam splitter 23 and the objective lens 25.

2 is a schematic view showing an optical disk 1 in which light spots are formed. The optical disc 1 includes a track helically formed circumferentially from its central root. Each track includes a land 2 on which information is recorded, and a groove 3 formed between each land 2 and the land 2. The diffraction grating in the 0 order light _{(21) (L 0),} +1 shielding (L _+1), -1 shielding (L _-1) respectively, at the same time maethinda in three different track position, as shown. That is, the + 1st light beam L ₊₁ is formed on the first track 30a of the optical disc 1, and the 0th light beam L ₀ is adjacent to the first track 30a. And the −1st light shield L _{−1 is} formed at the third track position 30c.

3 is a schematic diagram illustrating a photodetector 29 according to the present invention. As shown, the photodetector 29 includes first, second, and third photodetectors 29a, 29b, 29c, each of the two-photodetectors 29 being the first, second, and first. The signals reflected by the three tracks 30a, 30b and 30c are respectively received. The first photodetector 29a passes through the objective lens 50 after being reflected by the first track 30a and receives the light reflected by the beam splitter to receive the information signal of the first track 30a. The track error signal is detected. The third photodetector 29c receives the light reflected from the third track 30c and detects an information signal and a track error signal of the third track.

To this end, each of the first and third photodetectors 29a and 29c is formed of four partition plates G, H, I, J and K, L, M, and N which independently photoelectrically convert. The tracking error signal is detected by the light quantity difference or the phase difference by optical diffraction using the light received from the partition plates G, H, I, J and K, L, M, N. In addition, the signals received from the four split plates G, H, I, and J of the first photodetector 29a are summed to detect an information signal, ie, a radio frequency (RF) signal, for the first track 30a. In addition, the signals received from the four split plates K, L, M, and N of the third photodetector 29c are summed to detect an information signal, ie, a radio frequency (RF) signal, for the third track 30c. The second photodetector 29b receives the light reflected from the second track 30b and detects an information signal of the second track 30b and a focus error signal for correcting the position of the optical pickup device. To this end, the second photodetector 29b is formed of four split plates A, B, C, and D which independently photoelectrically convert.

In addition, the present invention may further include an astigmatism lens 27 on the optical path between the optical path converting means 23 and the photodetector 29. Since this astigmatism lens 27 is widely known, its detailed description is omitted.

The optical pickup device provided as described above reads the information of the first, second and third tracks 30a, 30b and 30c during one rotation of the optical disc 1. The read signals are stored in a memory device or the like and sequentially reproduced by a signal processing method. Further, it is designed so that track jumping can be performed in units of three tracks during information reproduction so that the same tracks are not duplicated as the optical disc 1 rotates.

Therefore, the optical pickup apparatus according to the present invention can detect the signals of several tracks at the time of one rotation of the optical disc by diffracting the light emitted from a single light source in multiple, and allowing each of them to simultaneously form on several tracks of the optical disc Therefore, the information processing speed can be greatly increased without increasing the rotation speed of the optical disc.

Claims (1)

A light source; Grating for diffracting the incident light from the light source into zero order diffraction light, +1 order diffraction light, and -1 order diffraction light; Optical path converting means for converting a traveling path of the zeroth order and ± first order diffracted light; An objective lens for concentrating zeroth order and ± first order diffracted light incident from the light source, so that each of the diffracted light is formed on different tracks of the optical disk recording surface; Four split plates (G, H, I, J) for independently photoelectric conversion of the received light, and receiving the + first order diffracted light reflected from the optical disk to the track error signal and the first track of the optical disk A first photodetector for detecting information about the apparatus; Four divided plates A, B, C, and D for photoelectric conversion independently of the received light, and receive the zero-order diffracted light reflected from the optical disk to provide a focus error signal and a second track of the optical disk. A second photodetector for detecting information; Comprising four split plates (K, L, M, N) for independently photoelectric conversion of the received light, receives the -first diffraction light reflected from the optical disk and detects a track error signal with the first photodetector And a third photodetector for detecting information on a third track of the optical disc. And information on three tracks of the optical disc can be read simultaneously.