JPH0652579B2 - Optical information recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical information recording / reproducing apparatus that records or reproduces information by light energy.

BACKGROUND ART In an optical information recording / reproducing apparatus, in order for a pickup, which is an optical means, to always accurately follow a recording track of an information recording disk, a tracking error signal is generated, and a tracking error signal is generated based on the tracking error signal. A tracking servo system that controls the position of the pickup in the radial direction of the disk is essential. There is a so-called three-beam method as a method of generating the tracking error signal.

1 and 2 are diagrams for explaining the operation and operation of the three-beam method. In FIG. 1, reference numeral 1 is an information pit forming a recording track, and in addition to the recording information detecting beam spot 2, a pair of tracking information detecting beam spots 3 and 4 preceding and succeeding the beam spot 2 are provided. Is irradiated onto the recording surface from a pickup (not shown).

In FIG. 2, the light passing through the recording surface of the beam spot 2 is introduced into a so-called four-division type photodetector 5.
The four outputs of the split photodetector 5 are added by an adder (not shown) to form a read signal. A pair of photodetectors 6 and 7 for detecting the light of the pair of beam spots 3 and 4, respectively.
The outputs A and B are subtracted by the subtracter 8, and the subtraction output C becomes the tracking error signal.

Here, in FIG. 3, the track pitch of the recording tracks 9 formed by the information pits 1 is a, and the distance between the beam spots 2 and 3, 4 in the disk radial direction is b.
And the distance b is, for example, 1/4 of the track pitch a.
By setting (b = a / 4), the tracking error signal as shown in FIG. 4 can be obtained according to the deviation amount of the recording information detecting beam spot 2 from the center of the recording track. Then, in the tracking servo system, the relative position of the pickup and the recording track 9 in the disc radial direction is controlled so that the tracking error signal becomes zero.

Meanwhile, digital audio discs, video discs, and the like are known as information recording discs, and disc players capable of reproducing both of these discs have recently been developed and put into practical use. However, the recording track track pitch differs depending on the type of the disk. As described above, the case where a pickup is used in which the distance b between the beam spots 2 and 3 and 4 in the disk radial direction is preset with the track pitch a as a reference is used. Considering this, in a disc having a track pitch a ₁ wider than the track pitch a as shown in FIG. 5, a tracking error signal with a gentle slope near the zero cross is obtained as shown in FIG. With a disc having a track pitch a ₂ narrower than the pitch a, a tracking error signal having a small absolute value is obtained as shown in FIG. Therefore, when performing special operations such as track jump or tracking servo gain control based on the tracking error signal, there is a possibility that these special operations cannot be performed accurately.

The relative positions of the beam spots 2, 3 and 4 are strictly set in advance in the optical system, and it is obvious that it is not easy to change the relative positions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide an optical information recording / reproducing apparatus capable of performing stable operation with respect to any track pitch.

An optical information recording / reproducing apparatus according to the present invention includes a pair of photodetectors, and an information detecting light beam and an information detecting light beam sandwiched between recording tracks on a recording surface of an information recording disk with respect to the recording track. Optical means for irradiating a pair of tracking servo light beams arranged on a straight line having a predetermined angle and for guiding each of the tracking servo light beams passing through the recording surface to the corresponding photodetector; A tracking error signal including means for generating a tracking error signal according to the deviation amount of the information detecting light beam with respect to the center of the recording track based on each output of the detector; and a controlling means for controlling the angle. An optical information recording / reproducing apparatus for performing tracking servo based on a signal, wherein the control means comprises the optical means and the information recording means. At least one of the disc and has a moving means for moving in a predetermined tangential direction of the information recording disc.

In the optical information recording / reproducing apparatus of the present invention, when at least one of the optical means and the recording disk moves in a predetermined tangential direction of the disk, the angle formed by the straight line connecting the tracking servo light beams and the recording track changes. The distance between the tracking servo light beam and the recording track in the radial direction of the disk changes. Therefore, it is possible to generate a tracking error signal suitable for tracking servo according to the track pitch of the recording track. Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In the present invention, the beam spot 2 with respect to the track pitch
In order to keep the distance between the recording disk 3 and the recording disk 4 in the radial direction of the disk constant regardless of the change in the track pitch, a line connecting the pair of tracking information detecting beam spots 3 and 4 irradiated on the recording surface of the disk. The relative angle formed by the tangent line of the recording track 9 of the disc is set according to the track pitch.

For example, as shown in FIG. 9, the relative angle is set to the disc 11 with respect to the pickup 10 which emits three light beams.
Is the moving direction of the pickup 10 (disc radial direction) X
It is set by moving according to the track pitch in a direction Y substantially perpendicular to.

That is, the track pitch a ₁ is the reference track pitch a
If it is wider (in the case of FIG. 5), the track pitch is curved by moving the disk 11 in the downward direction of the drawing with respect to the pickup 10. Depending on the amount, the relative angle changes in the direction of increasing. And its relative angle θ
_1, is the interval _{b 1} in the radial direction of the disk and the beam spot 2 and 3, 4 may be set so that, for example, _{quarter-track} pitch _{a 1 (b 1 = a 1} /4). On the other hand, when the track pitch a ₂ is narrower than the reference track pitch a (in the case of FIG. 7), the disk 11 is moved in the upward direction of the drawing with respect to the pickup 10 as shown in FIG. The relative angle changes in the direction of decreasing according to the amount of movement. Then, the relative angle θ ₂ is set so that the space b ₂ between the beam spots 2 and 3, 4 in the disk radial direction is the track pitch a ₂
For example it can I set so that the quarter _{1 (b 2 = a 2/} 4).

Although the distance between the beam spots 2 and 3 and 4 in the radial direction of the disk is set to 1/4 of the track pitch,
Depending on the type of disc, each separately or a quarter
It is also possible to set it to a value other than.

By the way, in a disc player capable of reproducing both a digital audio disc and a video disc,
As shown in FIGS. 2A and 2B, the two types of spindle motors 12a and 12b are interchanged. In FIG. 12 (A), two types of spindle motors 12a and 12b corresponding to the respective discs are held at a constant angle and swingably supported, and the spindle motor 12a abuts on the stopper 13b. The spindle motor 12b is placed in a substantially vertical state so that the video disk can be played back.
Is brought into contact with the stopper 13a, the spindle motor 12a is brought into a substantially vertical state, and the digital audio disk can be reproduced. In FIG. 12 (B),
Both spindle motors 12a and 12b are provided so as to be kept at a constant interval and movable integrally, and each stopper 1
By contacting the discs 3a and 13b, each disc can be reproduced.

Here, it can be understood that the positions of the spindle motors 12a and 12b in the disk radial direction, that is, the position of the disk 11 in the Y direction in FIG. 9 can be easily changed by adjusting the positions of the stoppers 13a and 13b. Therefore, by adjusting the positions of the stoppers 13a and 13b in accordance with the track pitch of the disc to be reproduced, the space between the beam spots 2 and 3 and 4 in the disc radial direction can be easily set to a set value corresponding to the track pitch. You can do it.

The positions of the stoppers 13a and 13b may be manually adjusted according to the track pitch, or may be automatically adjusted according to the input track pitch information by using an automatic feed mechanism. Since the track pitch is determined for each disc, the positions of the stoppers 13a and 13b are calculated according to the track pitches, and the positions are preset for each disc. The position can be easily adjusted.

Although the disc is moved with respect to the pickup in the above embodiment, the line connecting the pair of tracking information detecting beam spots irradiated onto the recording surface of the disc and the tangent to the recording track of the disc are formed. Since it suffices that the relative angle is changed, the pickup may be moved with respect to the disc, or the relative position of both in the disc radial direction may be fixed and the pickup may be moved along its optical axis (recording information detection beam). It may be rotated around a spot), and the same effect as that of the above-described embodiment is obtained.

As described above, according to the present invention, a pair of tracking information detection beams irradiated on the recording surface of the disc by moving at least one of the optical means and the disc in a predetermined tangential direction of the disc. Since the angle formed by the straight line connecting the spots and the tangent to the recording track of the disc changes and the distance between the tracking servo light beam and the recording track in the disc radial direction changes,
An optimum tracking error signal for tracking servo can be obtained according to the track pitch of the recording track.

[Brief description of drawings]

FIG. 1 is a diagram showing a positional relationship between a recording track and a detection beam spot, FIG. 2 is a block diagram for generating a tracking error signal, and FIG. 3 is a positional relationship between a recording track and a detection beam spot at a reference track pitch. FIG. 4 is a diagram showing a tracking error signal obtained by the positional relationship of FIG. 3, FIG. 5 is a diagram showing a positional relationship between a recording track and a detection beam spot at a track pitch wider than the reference track pitch, FIG. 6 is a diagram showing a tracking error signal obtained from the positional relationship of FIG. 5, FIG.
FIG. 8 is a diagram showing a positional relationship between a recording track and a detection beam spot at a track pitch narrower than the reference track pitch, FIG. 8 is a diagram showing a tracking error signal obtained by the positional relationship shown in FIG. 7, and FIG. 9 is the present invention. FIG. 10 is a diagram for explaining the operation of the present invention when the track pitch is wider than the reference track pitch, and FIG. 11 is the present invention when the track pitch is narrower than the reference track pitch. 12A and 12B are schematic configuration diagrams showing a spindle motor replacement mechanism in a digital audio disc / video disc player. Explanation of symbols of main parts 2 ... Beam spot for recording information detection 3, 4 ... Beam spot for tracking information detection 9 ... Recording track 10 ... Pickup 11 ... Information recording disk 12a, 12b ... Spindle motor 13a, 13b ... Stopper

Claims (1)

[Claims] 1. A pair of photodetectors, and a straight line having a predetermined angle with respect to the recording track on both sides of the information detection light beam and the information detection light beam on a recording track on the recording surface of the information recording disk. Optical means for irradiating a pair of tracking servo light beams arranged above and guiding each of the tracking servo light beams passing through the recording surface to the corresponding photodetector, and to each output of the photodetector. A tracking servo signal based on the tracking error signal; and a means for generating a tracking error signal according to the deviation amount of the information detection light beam with respect to the center of the recording track, and a control means for controlling the angle. An optical information recording / reproducing apparatus which comprises: the control means includes at least one of the optical means and the information recording disc. An optical information recording / reproducing apparatus having a moving means for moving the information recording disk in a predetermined tangential direction.