JPH04307431A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To correct focusing without providing a device directly detecting a tilt amount by correcting a tracking based on a track offset amount and correcting focusing based on a focus offset amount. CONSTITUTION:An electric signal of a tilt amount X from a tilt amount conversion circuit 15 is converted into a focus offset amount Z in a focus offset conversion circuit 17, the obtained amount is subtracted from a focus error signal for focus control, and a corrected focus error signal is transmitted to a focus control circuit. A tracking control circuit and a focus control circuit perform the tracking and focusing of a laser beam emitted from a light pickup 5 by means of the corrected track error signal and the corrected focus error signal.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording/reproducing apparatus for recording or reproducing information by irradiating a recording surface of an information recording medium with a laser beam.

0002

[Prior Art] The optical information recording/reproducing device (hereinafter also referred to as "optical disk drive device") as described above moves an optical pickup in the radial direction while rotating an information recording medium (hereinafter also referred to as "optical disk"). The laser beam from the semiconductor laser mounted on the optical pickup is focused by an objective lens to form a minute spot, and the optical spot is tracked and focused onto the recording surface of the optical disk to record or reproduce information. be.

For example, an optical disk drive device 20 shown in FIG. 11 includes a spindle motor 6 that rotationally drives an optical disk 2, an optical pickup 5, and
A coarse movement motor (seek motor) 22 that moves a large distance in the radial direction at high speed, a rotation control system 23, a pickup control system 24, and a coarse movement motor control system 2 that control these motors, respectively.
5, and a drive controller 27 that collectively manages each control system based on instructions from a signal processing system 26 and a drive interface.

The optical pickup 5 includes a semiconductor laser, an optical system, and actuators for tracking and focusing, and irradiates the recording surface of the rotating optical disk 2 with a focused laser beam L to record information thereon. Write to and read information from.

On the other hand, as shown in FIG. 12, a typical structure of this type of optical disc 2 includes two donut-shaped disk substrates 2 each having an information recording layer 28 formed thereon.
9 and 30 facing each other, and annular inner spacers 3 are provided on the inner and outer peripheries, respectively, to form an air layer between them.
1 and the information recording layer 2 bonded together via an outer spacer 32, or as shown in FIG.
There is one that consists of a substrate 33 that is a single donut-shaped disk with a number 8 formed thereon. In addition, 34 in FIG. 12 and 35 in FIG.
is a catching hub to be attached to the rotating shaft of the spindle motor 6.

[0006] Such an optical disk drive device 36
When the optical disk 2 is mounted on the disk, the spindle motor 6, optical pickup 5, coarse motor 22, field coils (not shown), their drive circuit elements (power transistors), etc. are unevenly distributed under the optical disk 2. Generates heat while driving due to high power level.

When the air warmed by the heat rises by convection, in the case of the optical disc 2 shown in FIG. 12, the lower substrate 30 warms and expands, causing the upper substrate 2 to expand.
9 does not expand much because it is kept at a relatively low temperature, so due to the difference in the degree of expansion between the two substrates 30 and 29,
As shown in an exaggerated manner in FIG. 14, it is warped toward the upper surface.

[0008] Furthermore, an optical disc 2 as shown in FIG.
Also in this case, the lower surface of the substrate 33 warms up and expands.
Since the upper surface side is kept at a relatively low temperature and does not expand much, the difference in the degree of expansion between the two surfaces causes it to warp toward the upper surface side as shown in an exaggerated manner in FIG.

As described above, when the optical disc 2 is deformed, the optical disc 2 is tilted (also referred to as "tilting") with respect to the optical axis of the laser beam L from the optical pickup 5, resulting in focus offset, track offset,
Alternatively, crosstalk may occur and accurate recording and reproduction of information may not be performed.

The optical disc 2 is tilted with respect to the optical axis of the laser beam L when an optical disc is initially warped during manufacturing or storage, or when the optical disc 2 and optical pickup 5 are tilted during driving. This can also occur due to errors in the assembly of the optical axis.

Conventionally, an optical pickup is provided with a detection device that detects the amount of tilt, which is the amount of inclination of the optical disk with respect to the optical axis of the optical pickup. A device has been proposed that corrects the focusing and tracking of a laser beam on an optical disk by tilting the entire optical pickup while it is being driven in accordance with the amount of tilt detected by the device (for example, see Japanese Patent Application Laid-Open No. 59-82641). has been done.

[0012] Furthermore, the tilt amount of the optical disc with respect to the optical axis of the optical pickup is detected by a tilt detection device provided in the optical pickup, and a focus offset correction signal and a track offset correction signal corresponding to this tilt amount are respectively converted into normal focus error signals. Some devices have been able to accurately record or reproduce information by focusing and tracking that remove focus offset and track offset in addition to the tracking error signal.

[0013]

[Problems to be Solved by the Invention] However, in such a device, it is necessary to provide a detection device for detecting the amount of tilt of the optical disk with respect to the optical axis of the optical pickup, so the scale of the optical pickup becomes large. There was a problem that the structure became complicated.

The present invention has been made in view of the above points, and it is possible to offset the focusing and tracking of a laser beam with respect to the tilt of an optical disk without providing a detection device for directly detecting the amount of tilt of the optical disk in the optical pickup. The purpose is to enable correction.

[0015]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a means for detecting the ambient temperature of an information recording medium and an ambient temperature detected by the means in an optical information recording/reproducing apparatus as described above. A means for converting the amount into a track offset amount and a focus offset amount is provided, and tracking is corrected using the track offset amount, and focusing is corrected using the focus offset amount.

The present invention also includes means for detecting the ambient temperature of the information recording medium, means for detecting the position of the objective lens with respect to the radial direction of the information recording medium, and a track offset amount that determines the position of the objective lens and the ambient temperature of the information recording medium. Also provided is a means for converting into a focus offset amount, the tracking is corrected by the track offset amount, and the focusing is corrected by the focus offset amount.

Alternatively, means for detecting the temperature difference between the upper and lower surfaces of the information recording medium and means for converting the temperature difference detected by the means into a track offset amount and a focus offset amount are provided, and tracking is performed using the track offset amount. The focusing may be corrected based on the focus offset amount.

Furthermore, means for detecting the temperature difference between the upper and lower surfaces of the information recording medium, means for detecting the position of the objective lens with respect to the radial direction of the information recording medium, and a means for detecting the temperature difference between the upper and lower surfaces of the information recording medium and the position of the objective lens in the radial direction of the information recording medium. It is also possible to provide means for converting the temperature difference into a track offset amount and a focus offset amount, and correct tracking using the track offset amount and correcting focusing using the focus offset amount.

[0019]

[Operation] The optical information recording/reproducing apparatus according to the present invention detects the ambient temperature of the information recording medium, and corrects tracking and focusing, respectively, based on the track offset amount and focus offset amount converted from the ambient temperature.

Alternatively, the ambient temperature of the information recording medium and the position of the objective lens in the radial direction of the information recording medium are detected, and tracking is performed using the track offset amount and focus offset amount converted from the ambient temperature and the position of the objective lens, respectively. and correct focusing.

Alternatively, the temperature difference between the upper and lower surfaces of the information recording medium is detected, and tracking and focusing are respectively corrected using a track offset amount and a focus offset amount converted from the temperature difference.

Alternatively, the position of the objective lens in the radial direction of the information recording medium is detected from the temperature difference between the upper and lower surfaces of the information recording medium, and the track offset amount and focus offset are calculated from the temperature difference and the position of the objective lens. Tracking and focusing are corrected depending on the amount.

Therefore, it is possible to correct offsets in tracking and focusing due to tilt when recording or reproducing information without providing a detection device for directly detecting the amount of tilt of the optical disk with respect to the optical axis of the optical pickup.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a vertical cross-sectional view showing a schematic configuration of an optical disk drive device according to a first embodiment of the present invention.

[0025] This optical disk drive device has a housing 1
A chassis includes a cartridge tray 4 into which a cartridge case 3 containing an optical disk 2 is mounted, and an optical pickup 5, a spindle motor 6, and a drive unit for a seek motor (coarse motor), which will be described later, are attached to the underside of the cartridge tray 4. It has 7.

The chassis 7 includes a spindle motor 6 for rotating the optical disc 2 and a spindle motor 6 as a mechanism for reading and writing information on the optical disc 2.
The turntable 8 is attached to the shaft of the optical disc 2 to fixedly support the optical disc 2.

Further, within this chassis 7, a laser beam is irradiated onto the recording surface of the optical disc 2 to form and detect pits, and also to perform focusing and tracking (positioning) on the recording surface. It houses an optical pickup 5, a seek motor (not shown) using a linear motor that moves the entire optical pickup 5 in its radial direction, and a linear encoder (not shown) that detects the approximate position of the optical pickup 5. There is.

Furthermore, the flexible print is equipped with an electric circuit for controlling focusing, tracking, seeking, etc. of the optical pickup 5, and an electric circuit for controlling emission of laser light from the optical pickup 5 and processing a pit detection signal. A board (not shown) is disposed on the chassis 7.

In such an optical disc drive device, the cartridge case 3 containing the optical disc 2 is inserted through the insertion slot 1a and mounted on the cartridge tray 4, and the optical pickup 5 is rotated as required while the optical disc 2 is rotated by the spindle motor 6. The laser beam from the semiconductor laser mounted on the optical pickup 5 is focused by the objective lens 9 to form a minute spot, and the optical spot is irradiated onto the recording surface of the optical disk 2 for focusing and tracking. to read and write information.

At this time, since the spindle motor 6, optical pickup 5, seek motor (not shown), their driving parts (power transistors, etc.), field coils, etc. attached to the chassis 7 have high power levels, During driving, heat is generated and the mounted cartridge case 3 and the optical disk 2 inside the cartridge case 3 are heated from below.

Then, as explained with reference to FIGS. 14 and 15, the optical disk 2 is warped upward and tilted with respect to the optical axis of the optical pickup 5. It is known that there is a certain relationship in which the amount of tilt, which is the amount of inclination, increases as the heating temperature for the optical disk 2 increases.

Therefore, as shown in FIG. 2, this optical disk drive device is provided with a temperature sensor 10 on the top surface of the chassis 7 for detecting the ambient temperature of the optical disk. Electronic circuit boards 12 and 13 are provided on which track offset removal circuits and focus offset removal circuits as shown are formed.

The track offset removal circuit (a) shown in FIG. 1 includes an ambient temperature detection circuit 14 and a tilt amount conversion circuit 1.
5, and a track offset conversion circuit 16, the ambient temperature detection circuit 14 detects the ambient temperature T of the optical disc 2 using the temperature sensor 10 and converts it into an electrical signal, and the tilt amount conversion circuit 15 converts it into the ambient temperature T. Convert to the corresponding tilt amount X.

The electrical signal of the tilt amount X is converted into a track offset amount Y by a track offset conversion circuit 16, and this is subtracted from the track error signal for tracking control to send a corrected track error signal to the tracking control circuit.

The focus offset removal circuit (b) also includes an ambient temperature detection circuit 14 and a tilt amount conversion circuit 15.
, a focus offset conversion circuit 17, and the ambient temperature detection circuit 14 and tilt amount conversion circuit 15 are common to the track offset removal circuit described above.

The electrical signal of the tilt amount X from the tilt amount conversion circuit 15 is converted into a focus offset amount Z by the focus offset conversion circuit 17, and this is subtracted from the focus error signal for focus control to convert the corrected focus error signal into the focus. Send to control circuit.

A tracking control circuit and a focus control circuit (not shown) perform focusing and tracking of the laser beam emitted from the optical pickup 5 based on the corrected track error signal and the corrected focus error signal.

Next, a second embodiment of the present invention will be explained. This embodiment takes into consideration the fact that when the optical disk is heated and tilted, the amount of tilt gradually increases depending on the position in the radial direction. The configuration of the optical disk drive device of this second embodiment is structurally the same as that of the first embodiment shown in FIG.
The circuit configurations formed on 2 and 13 are slightly different.

That is, in this embodiment, in order to correct tracking and focusing by taking into consideration the position of the objective lens 9 of the optical pickup 5 with respect to the radial direction of the optical disc 2 in addition to the ambient temperature of the optical disc, FIGS.
A track offset removal circuit and a focus offset removal circuit as shown in FIG.
is formed.

The track offset removal circuit shown in FIG. 3 is a circuit similar to that shown in FIG. 1(a) in which an objective lens position detection circuit 18 is added. Optical disc 2 detected by 10
The tilt amount conversion circuit 15 calculates the ambient temperature T by taking into account the position information r of the objective lens 9 detected by the objective lens position detection circuit 18 by obtaining an address from a signal read from the optical disk 2 by the optical pickup 5, for example.
' is converted into the tilt amount X.

The electrical signal of the tilt amount X is converted into a track offset amount Y by a track offset conversion circuit 16', and this is subtracted from the track error signal to send out a corrected track error signal.

Furthermore, in the focus offset removal circuit shown in FIG.
The focus offset conversion circuit 17' converts the electrical signal of the tilt amount X from the tilt amount conversion circuit 15' into a focus offset amount Z, and subtracts it from the focus error signal to perform a correction focus. Sends an error signal.

Then, tracking and focusing of the laser beam emitted from the optical pickup is performed using the corrected track error signal and the corrected focus error signal.

Next, a third embodiment of the present invention will be described. The structure of the optical disc drive device in this embodiment is almost the same as that shown in FIG. 2, but two temperature sensors are provided to detect the temperature difference between the upper and lower surfaces of the optical disc 2.

There is a certain relationship between the amount of tilt increase, which is the amount of tilt of the optical disc, the temperature difference between the upper and lower surfaces of the optical disc, and the radial position of the optical disc. For example, Figure 5 shows the relationship between the radial position (mm) and the tilt increase (°) when the temperature difference ΔT (°C) between the upper and lower surfaces of the optical disc is a, b, c (where a>b>c). As shown in the relationship, the amount of tilt increases approximately in proportion to the distance in the radial direction from the center of the optical disk, and the amount of increase in tilt increases as the temperature difference ΔT between the upper and lower surfaces of the optical disk increases.

Therefore, from this relationship, if the temperature difference ΔT between the upper and lower surfaces of the optical disk and the radial position of the optical disk (corresponding to the position information r of the objective lens) are known, the amount of tilt of the optical disk at that position can be estimated. In addition,
Relationship between this temperature difference ΔT and tilt increase amount (tilt characteristics)
Although there are some variations depending on the optical disc, it is known that the tendency is always constant, so it is possible to estimate the tilt amount within a certain error.

Furthermore, as shown in FIGS. 6 and 7, the amount of tilt of the optical disc 2 and the focus error signal and the tracking error signal are each in a nearly linear relationship, so the tracking error signal caused by the amount of tilt X The track offset amount Y and the focus offset amount Z of the focus error signal can be easily calculated. Therefore, as described above, tracking and focusing can be corrected using the track offset amount Y and the focus offset amount Z, respectively.

Therefore, as shown in FIG. 8, the optical disk drive device of the third embodiment includes, in addition to the temperature sensor 10 on the chassis 7 located near the bottom surface of the optical disk 2.
A temperature sensor 11 is also disposed on the cartridge tray 4 so as to be located near the top surface of the optical disc, and the electronic circuit board 1
2 and 13 are formed with a track offset removal circuit and a focus offset removal circuit shown in FIGS. 9 and 10, respectively.

The track offset removal circuit and the focus offset removal circuit are implemented by the temperature difference detection circuit 1 in place of the ambient temperature detection circuit 14 in each circuit shown in FIGS. 3 and 4.
9.

The temperature difference detection circuit 19 detects the temperatures of the upper and lower surfaces of the optical disk 2 using the temperature sensor 10 and the temperature sensor 11, converts the temperature difference ΔT into an electrical signal, and sends it to the tilt amount conversion circuit 15''. Tilt amount conversion circuit 15
″ is the optical disc 2 from the objective lens position detection circuit 18.
Taking into account the positional information r of the objective lens 9 in the radial direction, the temperature difference ΔT is converted into a tilt amount send.

The track offset conversion circuit 16'' converts the tilt amount X into a track offset amount Y, and sends out a corrected track error signal obtained by subtracting it from the track error signal. The amount X is converted into a focus offset amount Z, and a corrected focus error signal obtained by subtracting it from the focus error signal is sent.

Then, tracking and focusing of the laser beam emitted from the optical pickup is performed using the corrected track error signal and the corrected focus error signal.

Here, for example, if the change in the temperature of the upper surface of the optical disk 2 is smaller than the change in the temperature of the lower surface, and the temperature of the upper surface can be treated as a constant k, the optical disk drive device shown in FIG. The value obtained by subtracting k from the temperature T of the lower surface detected by the temperature sensor 10 at (T-k
) can be set to the temperature difference ΔT, so it is sufficient to provide only one temperature sensor.

That is, by arranging temperature sensors only at locations where temperature changes are severe, it is possible to estimate the tilt amount from the temperature detected by one temperature sensor and correct the track offset and focus offset accordingly. The first and second embodiments described above are based on such a case.

[0055]

As described above, the optical information recording and reproducing apparatus according to the present invention can focus a laser beam on an optical disk by tilting it, without having to provide an optical pickup with a detection device that directly detects the amount of tilt of the optical disk. and tracking offset can be corrected.

[Brief explanation of drawings]

[FIG. 1] Electronic circuit board 12, 1 of the first embodiment shown in FIG. 2.
3 is a block diagram of a track offset removal circuit and a focus offset removal circuit formed in FIG. 3. FIG.

FIG. 2 is a sectional view showing a schematic configuration of an optical disk drive device according to a first embodiment of the present invention.

FIG. 3 is a block diagram of a track offset removal circuit in a second embodiment of the invention.

FIG. 4 is a block diagram of the focus offset removal circuit.

FIG. 5 is a diagram showing a change in the amount of tilt increase depending on the temperature difference between the upper and lower surfaces of the optical disc and the position in the radial direction of the optical disc.

FIG. 6 is a diagram showing the relationship between tilt amount and focus error signal.

FIG. 7 is a diagram showing the relationship between the tilt amount and the tracking error signal.

FIG. 8 is a sectional view showing a schematic configuration of an optical disk drive device according to a third embodiment of the invention.

FIG. 9 is a block diagram showing the configuration of the track offset removal circuit.

FIG. 10 is a block diagram showing the configuration of the focus offset removal circuit.

FIG. 11 is a diagram showing a schematic configuration of a conventional optical disc drive device.

FIG. 12 is a sectional view showing an example of a conventional optical disc.

FIG. 13 is a cross-sectional view showing another example of a conventional optical disc.

FIG. 14 is an explanatory diagram showing how the optical disc shown in FIG. 12 is deformed by heating.

FIG. 15 is an explanatory diagram showing how the optical disc shown in FIG. 13 is deformed by heating.

[Explanation of symbols]

1,20 Optical information recording/reproducing device (optical disk drive device) 2 Optical disk
3 Cartridge case 4 Cartridge tray
5 Optical pickup 6 Spindle motor
7 Chassis 8 Turntable
9 Objective lenses 10, 11
Temperature sensor 12,1
3 Electronic circuit board 15, 15', 15'' Tilt amount conversion circuit 16, 16
', 16'' Track offset conversion circuit 17, 17
',17'' Focus offset conversion circuit 18
Objective lens position detection circuit 19 Temperature difference detection circuit

Claims (4)

[Claims] Claim 1: An optical pickup is moved in the radial direction while rotating an information recording medium, and a laser beam from a semiconductor laser mounted on the optical pickup is focused by an objective lens to form a minute spot. In an optical information recording and reproducing apparatus that records or reproduces information by tracking and focusing on a recording surface of an information recording medium, the apparatus includes a means for detecting an ambient temperature of the information recording medium, and a track offset for detecting the ambient temperature detected by the means. and a means for converting into an amount and a focus offset amount, and correcting the tracking according to the track offset amount,
An optical information recording and reproducing apparatus, characterized in that the focusing is corrected by a focus offset amount. [Claim 2] An optical pickup is moved in the radial direction while rotating the information recording medium, and a laser beam from a semiconductor laser mounted on the optical pickup is focused by an objective lens to form a minute spot. In an optical information recording and reproducing apparatus that records or reproduces information by tracking and focusing on a recording surface of an information recording medium, the optical information recording and reproducing apparatus includes means for detecting an ambient temperature of the information recording medium, and a radius of the information recording medium of the objective lens. A means for detecting a position with respect to a direction and a means for converting the position of the objective lens and the ambient temperature of the information recording medium into a track offset amount and a focus offset amount are provided, and the tracking is corrected by the track offset amount, and the focus offset is An optical information recording and reproducing apparatus, characterized in that the focusing is corrected depending on the amount. 3. An optical pickup is moved in the radial direction while rotating the information recording medium, and a laser beam from a semiconductor laser mounted on the optical pickup is focused by an objective lens to form a minute spot. An optical information recording and reproducing apparatus that records or reproduces information by tracking and focusing on a recording surface of an information recording medium, comprising means for detecting a temperature difference between upper and lower surfaces of the information recording medium, and a temperature difference detected by the means. What is claimed is: 1. An optical information recording and reproducing apparatus comprising: a means for converting the distance into a track offset amount and a focus offset amount; the tracking is corrected by the track offset amount; and the focusing is corrected by the focus offset amount. 4. An optical pickup is moved in the radial direction while rotating the information recording medium, and a laser beam from a semiconductor laser mounted on the optical pickup is focused by an objective lens to form a minute spot. In an optical information recording and reproducing apparatus that records or reproduces information by tracking and focusing on a recording surface of an information recording medium, there is provided a means for detecting a temperature difference between upper and lower surfaces of the information recording medium; A means for detecting the position of the medium in the radial direction and a means for converting the temperature difference between the position of the objective lens and the upper and lower surfaces of the information recording medium into a track offset amount and a focus offset amount are provided, and the tracking is performed using the track offset amount. An optical information recording/reproducing apparatus characterized in that the focusing is corrected based on a focus offset amount.