JPH0410227A - How to draw a light spot in an optical disc device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for drawing a light spot in an optical disc device for positioning a light spot emitted from an optical pickup between pre-groups for the purpose of tracking.
Especially for inspecting SFP zones on optical disks, S
The present invention relates to a method of drawing a light spot in an optical disc device suitable for drawing a light spot into a transition zone adjacent to an FP area.

[Prior Art] In conventional optical disk devices, a light spot is generally drawn between pregroups at the time when a tracking error signal crosses zero.

[Problems to be Solved by the Invention] The above-mentioned conventional technology has the following problems because the optical disc has eccentricity. In other words, when looking for the point where the tracking error signal becomes zero with the optical pickup lens in focus, the optical spot crosses many pre-groups due to the eccentricity of the optical disc, and as a result there are many zero-crossing points. Therefore, it becomes impossible to judge where to perform the retraction.

In particular, to inspect the SFP zone on the optical disk,
When drawing a light spot into the transition zone adjacent to the SFP zone, the drawing could not be performed unless the eccentricity of the optical disk was less than lOμI. However, since the eccentricity of an optical disk is allowed up to 50 μm, there is a problem in that if this amount of eccentricity is large, it becomes impossible to pull the disc into the transition zone.

Furthermore, in optical disks, in addition to the problem of eccentricity mentioned above, deviations due to thermal expansion and the like are allowed up to ±0.1 mm. Therefore, when the light spot is moved to the vicinity of the transition zone or to a place including the transition zone, there is a problem that it takes time to search for the transition zone.

Further, on the optical disc, as shown in FIG. 2, the SFP zone is formed from an address bit P indicating an ID and a pregroup PG. Then, on the inner circumferential side of the SFP zone, as shown in Fig. 3, there is a pre-group PG.
A transition zone is provided which is formed solely from the material. Further, on the inner circumferential side of the transition zone, as shown in FIG. 4, a PEP zone formed of bits called marks M is provided.

Therefore, in order to distinguish between the transition zone and the SFP zone, it is necessary to check the presence or absence of the ID (address bit P), but there is a problem that this cannot be easily determined due to the influence of eccentricity.

Note that Table 1 below shows the area allocation on the optical disc.

As is clear from Table 1 above, there are one SFP zone on the inner circumferential side and one on the outer circumferential side. Of these, it is the SFP zone on the inner circumferential side that becomes a problem.

The reason for this is that since the optical disc is formed in a spiral shape from the inner circumferential side, it is necessary to perform retraction in the transition zone in order to inspect the SFP zone on the inner circumferential side.

The present invention has been made in view of the problems of the prior art described above, and makes it possible to easily draw a light spot into a transition zone adjacent to an SFP area, particularly for inspecting an SFP zone on an optical disc. An object of the present invention is to provide a method for pulling in a light spot in an optical disc device, which makes it possible to easily draw in a light spot.

[Means for Solving the Problems] The optical spot bowing method in the optical disc device of the present invention includes detecting eccentricity data indicating the eccentric state of the optical disc in advance and recording it together with angle data indicating the rotation angle of the optical disc. When pulling a light spot in an optical disc device, it follows the eccentric state of the optical disc,
It is characterized by the fact that the light spot is pulled in by achieving a state in which the influence of eccentricity is eliminated.

[Operation] Optical discs are manufactured by transferring from a master mold called a stamper, and when manufacturing the stamper, the concentricity of the pre-groups is created with high precision.

Therefore, the main reason why the light spot does not travel along the pre-group of the optical disk is the eccentricity of the center of the hub and the receiving surface on which the hub is attached when the hub is attached. Therefore, in order to remove the effects of these eccentricities, it is necessary to examine the axis trace of the optical spot on the optical disk, and remove the effects of eccentricity by displacing the optical pickup itself or its pickup lens in the opposite direction to the axis trace. Just do it.

Therefore, in the present invention, data indicating the eccentricity state is stored in advance together with its angle data, and when the optical spot is drawn in, data indicating the eccentricity that matches the rotation angle of the optical disk is read out, and a state in which the influence of eccentricity is eliminated is obtained. This makes it easy to pull in the vehicle.

[Examples] The present invention will be described in more detail below with reference to Examples shown in the attached drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which 1 is an optical pickup, 2 is a servo circuit, 3 is a D/A converter, 4 is a tracking current detection circuit, 5 is a lens position sensor, and 6 is a block diagram showing an embodiment of the present invention. is an A/D converter, 7 is a CPU, 8 is a home position rotation position detection circuit, 9 is a memory, 10
11 indicates a motor, and 11 indicates an optical disk.

The CPU 7 controls the servo circuit 2 via the D/A converter 3 so that the light spot emitted from the optical pickup 1 is first positioned in an area where a suitable pre-group exists on the optical disc, and focusing and tracking are performed. do. In this state, the home position rotational position detection circuit 8 extracts the timing to notify the home position position and each rotation angle of the motor IO, and
Output to CPU7. At the above timing, the CPU 7 uses the lens position 5 to measure the position of the pickup lens mounted on the optical pickup. Here, instead of using the lens position sensor 5, the tracking current detection circuit 4 may be used to detect the current applied to the tracking coil and measure the lens position. C.P.
U7 stores lens position data and rotation angle data from the home position to the next home position in the memory 9 via the A/D converter 6.

Next, the operation of searching for a transition zone in order to inspect the SFP area will be described. With the light spot positioned near the transition zone, the CPU
7 reads from the memory 9 the lens position data in the rotation angle data that matches the rotation angle data output from the home position rotation position detection circuit 8, and outputs it to the servo circuit 7 via the D/A converter 3. That is, the eccentricity removal pattern is manually input to the servo circuit 2. Therefore, the pickup lens mounted on the optical pickup 1 is displaced according to the eccentricity of the optical disk 11.

Therefore, it is possible to read data from the optical disc 11 that is not affected by the eccentricity of the optical disc 11 at all.

That is, no bit signal is generated when the light spot is within the transition zone. Also,
If the light spot is within the PEP zone, a pit-influenced signal is generated.

If the optical spot does not exist in the transition zone, a bias may be added to the above-described eccentricity removal pattern, or the optical pickup 1 itself may be moved to search for the transition zone.

In the above embodiments, a case has been described in which the movement of the pickup lens is stored together with rotation angle data, but the present invention is not limited to this. Alternatively, the pickup lens may be vibrated at the outermost position of the optical disc, and based on the tracking error signal or RF multiplication signal when crossing the pre-group for the first time, the It is also possible to remove the influence of eccentricity from the position of the pickup lens (data can also be created).

Further, in the above embodiment, even after the light spot is drawn in, the lens position data is output from the D/A converter 3 to the servo circuit 2 to remove the influence of eccentricity. For example, the output from the D/A converter 3 may be stopped at the same time as the power is pulled in, or may be gradually reduced.

[Effect of the invention] As is clear from the above explanation, according to the present invention, SF
It is possible to provide a method of drawing a light spot in an optical disc device that can easily draw a light spot to a transition zone adjacent to the P area.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an SFP zone, FIG. 3 is an explanatory diagram showing a transition zone, and FIG. 4 is an explanatory diagram showing a PEP zone. It is. 1... Optical pickup, 2... Servo circuit, 3...
・D/A converter, 4... Tracking current detection circuit, 5... Lens position sensor, 6... A/D converter, 7... CPU, 8...
Home position rotational position detection circuit, 9... memory,
10...Motor, 11...Optical disk Hatakegandai Rico Co., Ltd.Figure 2Figure 1Figure 3Figure 4M mark

Claims (1)

[Claims] Eccentricity data indicating the eccentricity state of the optical disk is detected in advance and recorded together with angle data indicating the rotation angle of the optical disk, and when the optical disk device pulls a light spot, the eccentricity data that matches the rotation angle of the optical disk is detected. 1. A method for pulling in a light spot in an optical disc device, characterized in that the light spot is read out, the light spot follows the eccentric state of the optical disc, and the light spot is pulled in by achieving a state in which the influence of eccentricity is eliminated.