JPH09190634A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the quick discrimination of the disk kind of different recording surface height by driving an objective lens with a moving mechanism so as to perform a focusing operation and detecting the moving amount of this time by a moving amount detecting circuit. SOLUTION: A luminous flux emitted from a semiconductor laser 13 is converged to a disk 1 (1'). A reflected light from the disk is made incident on a photodetector 16. A detecting signal 21 from the photodetector 16 enters a preamplifier 22, and a pit detecting signal 23, a focus error signal 24 and a tracking error signal 26 are outputted from the preamplifier 22. The signal 24 is outputted to a focus control circuit 31 and a focus control signal 32 is outputted from the circuit 31. The signal 32 is outputted to a moving amount detecting circuit 11 and the detecting data signal 10 of the moving amount is outputted from the circuit 11 to a microcomputer 28. The moving amount of a lens holder 4 is known by the signal 10 during a focusing operation and by a determination signal 39 from a focus detecting circuit 38, the variety of a disk having a different recording surface height is discriminated by the microcomputer 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for optically reproducing or recording / reproducing a signal from a disk, and more particularly to the height of a recording surface from a light input / output surface of the disk (hereinafter, simply referred to as the height of the recording surface. The present invention relates to an optical disc device capable of reproducing or recording / reproducing two or more types of discs different from each other.

[0002]

2. Description of the Related Art Currently, as optical disk devices, compact disk (hereinafter referred to as CD) players and laser disks (hereinafter
There is a player). Although these devices differ in the outer diameter size and thickness of the disc, the height of the recording surface is the same at 1.2 mm, and since the optical system can be used in common, one device can be used for CD and LD. A device that can reproduce is also commercialized. An example of this type of device is a product such as "CLD-Z1" from Pioneer Corporation.

[0003]

However, recently, a digital video disc (hereinafter referred to as DV) capable of recording not only audio but also video information by increasing the recording density of the disc has been recently used.
The standard for high-density recording discs such as D) is determined, the track pitch is narrower from 1.6 μm to 0.74 μm, and the laser wavelength is 780 nm compared to CD.
To 650 nm, and the numerical aperture (NA) of the lens is increased from 0.45 to 0.60. In order to mitigate the adverse effect that the permissible value of the angle (tilt angle) with which the disc surface deviates from the optical axis of the optical pickup becomes smaller due to the increase in the numerical aperture (NA) along with the increase in the density, Despite having the same external size as a CD, the height of the recording surface is D compared to 1.2 mm (single plate) of a CD
VD is set to 0.6 mm (two pieces are stuck together). Therefore, although there are discs of the same size at first glance, there are discs of different standards. Naturally, a DVD-compliant optical disc device that will be commercialized later will be a DVD.
Needless to say, it is required that the reproducing operation can be performed correspondingly to the CD.

However, since the standard is different between CD and DVD, it is necessary to switch the objective lens and the signal processing system suitable for each disc in order to reproduce each disc, and which disc is mounted when the disc is mounted. It is necessary to determine whether or not And
It is desired to realize an optical disk device capable of quickly discriminating between a CD and a DVD and automatically switching the objective lens and the signal processing system according to the mounted disk.

[0005] The present invention has been made in view of the above points,
The purpose is to quickly and easily discriminate both high density discs such as DVDs and conventional CDs, and switch to the objective lens and signal processing system corresponding to the discs discriminated to reproduce. Another object is to realize an optical disk device capable of recording and reproducing.

[0006]

In order to achieve the above object, the present invention provides an objective lens for focusing a laser beam on the recording surface of a disc, which is driven by a moving mechanism when the disc is mounted. The operation is performed, and the movement amount at that time is detected by the movement amount detection circuit.

Further, two or more objective lenses corresponding to discs having different recording surface heights are provided, and the objective lenses are switched according to the disc discrimination result.

Further, the focusing operation is performed in advance for each of two or more kinds of disks, and the drive voltage applied to the moving mechanism when the objective lens is in focus, or
Memorize the magnitude of the drive current,
The drive voltage or drive current is detected by the movement amount detection circuit, and the disc type is discriminated by comparing the detected drive voltage or drive current with the stored drive voltage or drive current.

Further, a focus detection circuit for detecting that the objective lens is in focus is provided from the signal read from the recording surface of the disk during the focusing operation of the objective lens.

With the above arrangement, the amount of movement of the objective lens when the operation of focusing the laser beam on the recording surface of the disk is performed can be detected by the movement amount detection circuit. It is possible to discriminate between two or more types of discs having different heights of the recording surface of the disc.

Further, since two or more objective lenses corresponding to two or more kinds of discs having different recording surface heights are provided, and the objective lenses can be switched and used,
The objective lens can be switched to an optimum one according to the disc type that has been discriminated.

Further, the movement amount detection circuit detects the drive voltage or drive current applied to the movement mechanism, and the objective lens when two or more kinds of disks having different recording surface heights are in focus Relationship between the amount of movement and the magnitude of the drive voltage or drive current applied to the movement mechanism,
Since it is stored in advance, the movement amount detection circuit detects the drive voltage or drive current applied to the movement mechanism when the objective lens is in focus, and compares this with the prestored data. As a result, the amount of movement of the objective lens can be known, and the type of disc can be determined from the amount of movement.

Since the focus detection circuit can detect that the objective lens is in focus from the signal read from the recording surface of the disk, the amount of movement when the objective lens is in focus can be known accurately. The disc can be easily and surely discriminated.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below with reference to an optical disk device according to one embodiment of the present invention (hereinafter referred to as the present embodiment) shown in FIGS. 1 and 2 are cross-sectional views of a main part around the objective lens in the optical disk device of the present example, for explaining the focusing operation of the objective lens, and FIG. 3 is a diagram for explaining the switching operation of the objective lens. FIG. 3 is a cross-sectional view of a main part around an objective lens in the optical disc device of this example.

In FIGS. 1 to 3, 1 and 1'are discs (1 is a DVD, 1'is a CD), 2 is a DVD objective lens with a numerical aperture (NA) of 0.6 for DVD, and 3 is for CD. Objective lens with a numerical aperture (NA) of 0.45, 4 is a DVD
A lens holder holding the objective lens 2 and the CD objective lens 3, 5 is a yoke of an actuator for driving the lens holder 4, and 6 is a shaft which supports the lens holder 4 so as to be rotatable and slidable. Also, 1a is a disc 1
The recording surface 1b is the recording surface of the disc 1 ', and the recording surface 1a is located at a height of 0.6 mm from the light entrance / exit surface (the reading side surface) of the disc 1. Is
It is located at a height of 1.2 mm from the light entrance / exit surface (reading surface) of the disc 1 '.

One end of a shaft 6 is fixed to the yoke 5, and a focusing coil and a tracking / not shown
A lens switching coil is attached. Also,
Magnets (not shown) are attached to the lens holder 4 at positions facing the coils. Then, by appropriately supplying a drive voltage to each of the above coils, the focusing operation of the objective lens from the initial position and the tracking / lens switching operation are performed. That is, the lens holder 4 is
When rotated, the positions of the DVD objective lens 2 and the CD objective lens 3 are exchanged, and the objective lenses can be switched.

In this example, when the disc 1 or the disc 1'is mounted in the apparatus, first, the focusing operation is performed using the DVD objective lens 2.
The yoke 5 has a hole 5a through which a light beam emitted from a laser light source (not shown) passes, and the light beam strikes the recording surface of the disk through the first prepared DVD objective lens 2 from this hole 5a. Then, by supplying a drive voltage to a focus coil (not shown), the lens holder 4
Focusing is performed by sliding along the axis 6 as indicated by the arrow in the figure.

FIG. 1 shows a state in which a focusing operation is performed immediately after the disc 1 (DVD) is mounted on the optical disc apparatus of this example. Δ1 in FIG. 1 represents the amount of movement of the lens holder 4 from the initial reference position S _REF when the disc 1 (DVD) is mounted, that is, the amount of movement of the DVD objective lens 2. In this example, this δ1
The relationship with the drive voltage value at this time is previously checked and stored. Therefore, by detecting the drive voltage of the focusing operation when the disc 1 (DVD) is mounted, it is found that the movement amount of the lens holder 4 is δ1, and it is possible to determine that the disc is a DVD. There is.

FIG. 2 shows how the focusing operation is performed immediately after the disc 1 '(CD) is mounted on the optical disc apparatus of this example. Δ2 in FIG. 2 represents the amount of movement of the lens holder 4 from the initial reference position S _REF , that is, the amount of movement of the DVD objective lens 2 when the disc 1 ′ (CD) is mounted. In this example, this δ2
The relationship with the drive voltage value at this time is previously checked and stored. Therefore, by detecting the drive voltage of the focusing operation when the disc 1 '(CD) is mounted, it is found that the movement amount of the lens holder 4 is δ2, and the disc can be discriminated as a CD. ing.

As described above, it is used when the disc mounted in the optical disc device is discriminated as the CD (disc 1 ') (in other words, the hole 5 of the yoke 5).
Since the objective lens (facing a) should be the CD objective lens 3 instead of the DVD objective lens 2, the lens switching operation is performed. That is, the lens holder 4 is attached to a tracking / lens switching coil (not shown).
By supplying the drive voltage so as to rotate 80 °, the lens holder 4 rotates from the state shown in FIG. 2 to the state shown in FIG. 3, and the DVD objective lens 2 moves to the CD objective lens 3. The lens switching operation is performed. Then, since there is a difference in the focal position between the DVD objective lens 2 and the CD objective lens 3, the focusing operation by the CD objective lens 3 is performed again, and the lens holder 4 is moved to δ in FIG.
The signal read operation is performed at the position of the movement amount of 2 '.

FIG. 4 is a block diagram showing the configuration of the optical disk device of this example. In the optical pickup PU, the lens holder 4, the yoke 5, the shaft 6, the focus coil (not shown), and the tracking / lens described above are provided. Switching coils etc. are attached.

In the configuration shown in FIG. 4, when a disc is loaded, a laser drive circuit 35 generates a laser drive signal 37 in response to a control signal 20 from a microcomputer (hereinafter referred to as a microcomputer) 28, and a pickup is performed. The semiconductor laser 13 of PU is turned on. The light flux emitted by the semiconductor laser 13 is reflected by the half mirror 15,
The light is reflected by the reflection prism 14, enters the DVD objective lens 2 attached to the lens holder 4, and is condensed on the disc. The reflected light from the disc is the DVD objective lens 2
Is reflected by the reflection prism 14 via the half mirror 1
After passing through 5, the light enters the photodetector 16. Photo detector 16
The detection signal 21 from is input to the preamplifier 22, and the preamplifier 22 outputs a pit detection signal 23, a focus error signal 24, and a tracking error signal 26, respectively. Here, when the disc is not rotating, the pit detection signal 23 and the focus error signal 24 are used for focusing, but the tracking error signal 26 cannot be correctly output unless the disc is rotating.

The focus error signal 24 is sent to the microcomputer 28.
And a focus control circuit 31. Based on the focus error signal 24 and the control signal 25 from the microcomputer 28, the focus control circuit 31 outputs a focus control signal 32 to a focus coil (not shown). It is supplied and focus control is performed. Also,
The focus control signal 32 is also output to the movement amount detection circuit 11, and the movement amount detection circuit 11 detects the drive voltage supplied to the focus coil. Then, the movement amount detection circuit 11 compares the drive voltage data recognized from the focus control signal 32 with the drive voltage data that is learned and stored in advance, and determines the relationship between the drive voltage value and the movement amount described above. The movement amount of the lens holder 4 at that time is detected, and the movement amount detection data signal 10 is sent to the microcomputer 2
8 is output.

The pit detection signal 23 output from the preamplifier 22 corresponds to the data recorded on the disc and is output to the focus detection circuit 38 and the signal processing circuit 9. The focus detection circuit 38 determines from the pit detection signal 23 whether or not the focus of the objective lens is on the recording surface of the disc, and outputs the determination signal 39 to the microcomputer 28, which causes the microcomputer 28 to focus. Recognize whether or not

Therefore, the movement amount detection data signal 10 from the movement amount detection circuit 11 indicates the movement amount of the lens holder 4 (the movement amount of the objective lens) during the focusing operation (in other words, the recording surface of the disc). The position of the target lens can be recognized), and it is possible to know whether or not the focus of the objective lens is accurately focused on the recording surface of the disc by the determination signal 39 from the focus detection circuit 38. The amount of movement of the objective lens at the time of accurate focusing makes it possible to easily and reliably determine the type of disc having a different recording surface height.

Then, according to the disc type that is determined,
The control signal 27 is input from the microcomputer 28 to the tracking / lens switching control circuit 29. If the disc initially loaded in the apparatus is a CD (disc 1 '), the tracking / lens switching control signal 30 is output from the tracking / lens switching control circuit 29, and the tracking / lens switching control signal 30 is output as described above. The lens switching control from the DVD objective lens 2 to the CD objective lens 3 is performed.

As described above, after the focusing operation on the recording surface of the disc is performed, the disc type is discriminated, and the lens is switched if necessary, the normal reproducing operation is performed. First, the control signal 19 from the microcomputer 28
Causes the spindle motor control circuit 8 to generate a motor drive signal 18 to rotate the spindle motor 12,
At the rotation speed according to the disc type (disc 1
Alternatively, the disc 1 ') is rotated. In addition, the pit detection signal 23, the focus error signal 24, and the tracking error signal 26 are output from the preamplifier 22 in the course of the laser driving described above.

As described above, the focus error signal 24 is output to the microcomputer 28 and the focus control circuit 31, and the focus control circuit 31 outputs the focus error signal 24 and the control signal 25 from the microcomputer 28. Based on this, the focus control signal 32 is output and supplied to a focus coil (not shown) of the optical pickup PU, and focus control is performed. In addition, the tracking error signal 26 is output to the microcomputer 28 and the tracking / lens switching control circuit 29, and
The lens switching control circuit 29 outputs a tracking / lens switching control signal 30 based on the tracking error signal 26 and the control signal 27 from the microcomputer 28, which is a tracking / lens switching coil (not shown) of the optical pickup PU. And the tracking control is performed. In addition, the pit detection signal 23 is
The data is output to the signal processing circuit 9, and the signal processing circuit 9 performs appropriate data conversion processing according to the disc type. Furthermore, in order to move the pickup PU in the radial direction of the disc, a control signal 3 from the microcomputer 28 is sent.
Based on 3, the feed motor control circuit 34 outputs the feed control signal 36 to the motor of the feed mechanism (not shown) to move the pickup PU in the radial direction of the disc by the feed mechanism.

FIG. 5 is a process flow chart showing an example of the flow of the disc discrimination process according to this embodiment. First, when a disc is mounted (step ST1), a focusing operation for focusing the DVD objective lens 2 is performed according to a command from the microcomputer 28 (step ST2). Then, in step ST3, it is determined whether or not the focus is achieved by the focus operation. If the focus is not achieved, the process returns to step ST2 to continue the focus operation, and if the focus is achieved, the step is performed. Go to ST4.

In step ST4, the magnitude of the drive voltage to the focus coil when the focus is achieved is acquired, and the process proceeds to step ST5. In step ST5, step ST
Driving voltage data acquired in 4 and DVD (disk 1) and CD (disk 1 ') acquired and stored in advance
The drive voltage data obtained during step ST4 is compared with the drive voltage data obtained during step ST4, and the drive voltage data obtained during step ST4 is within the allowable variation range and substantially coincides with the drive voltage data obtained during the DVD focus operation. For example, the process proceeds to step ST6, it is determined that the disc is the DVD (disc 1), the lens switching operation is not performed, and this flow is ended. In step ST5, if the drive voltage data acquired in step ST4 is within the permissible variation range and substantially coincides with the drive voltage data stored in advance during the CD focus operation, the process proceeds to step ST7. It is determined that the disc is a CD (disc 1 '), and the next step S
At T8, lens switching from the DVD objective lens 2 to the CD objective lens 3 is performed, and this flow ends.

Here, in the above-described example, the initial focusing (focusing operation) when the disc is mounted in the optical disc device is performed by the DVD objective lens 2, but the initial focusing is performed by the CD objective. Lens 3
It goes without saying that it does not matter if it is done by.

Further, in the above-mentioned present example, although it was mainly explained that the objective lens is automatically switched according to the disc type that was discriminated, the signal processing system (spindle motor control circuit 8, signal processing circuit 9, tracking / It goes without saying that the lens switching circuit 29 etc.) is automatically switched to a processing function system suitable for the disc type according to the disc type.

As described above, in the present embodiment, the disc type is discriminated quickly by the focusing operation performed by a normal device by providing the movement amount detection circuit 11.
Easy and reliable. Further, since the movement amount detection circuit 11 can be built in the microcomputer 28, it can be realized at low cost without increasing the number of parts.

Although the above-described example is an example of application to a reproducing device, the present invention can be similarly applied to a recording / reproducing device, and a moving amount detecting circuit drives in place of a driving voltage. The same effect can be obtained by detecting the current. Furthermore, even if three or more types of discs are compared, it is possible to make a similar determination by sequentially comparing the drive voltages (or drive currents), and the present invention is not limited to the above-described embodiments. Various modifications are possible without departing from the spirit of the invention.

[0035]

As described above, according to the present invention, the movement amount of the focusing operation of the objective lens is detected by the movement amount detection circuit, and the disc type is determined based on the movement amount detection circuit. It is quick and easy to discriminate between two or more disc types with the same recording height but different recording surfaces.
It can be done reliably. Therefore, the switching to the optimum objective lens or the switching to the optimum processing circuit system can be quickly performed according to the type of the disk, and the usability is greatly improved. Further, since it is only necessary to add a movement amount detection circuit for judging the disc type, it is possible to realize at low cost and the value thereof is great in this type of optical disc device.

[Brief description of the drawings]

FIG. 1 is a sectional view of essential parts showing a state of a focusing operation of an objective lens when a DVD is mounted in an optical disc device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a state of a focusing operation of an objective lens when a CD is mounted in the optical disc device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts showing a state of an objective lens switching operation in the optical disc device according to the first embodiment of the present invention.

FIG. 4 is a block diagram of an optical disk device according to an embodiment of the present invention.

FIG. 5 is a flow chart diagram showing an example of the flow of disk discrimination processing according to an embodiment of the present invention.

[Explanation of symbols]

 1 disc (DVD: digital video disc) 1a recording surface 1'disc (CD: compact disc) 1b recording surface 2 DVD objective lens 3 CD objective lens 4 lens holder 5 yoke 5a hole 6 axis 11 movement amount detection circuit 22 preamplifier 28 microcomputer (Microcomputer) 29 Tracking / lens switching circuit 31 Focus control circuit 38 Focus detection circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Naohiko Ochi, Inventor Naohiko Ochi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Multimedia System Development Division (72) Yukio Fukui Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Address 292 Hitachi, Ltd. Multimedia System Development Division

Claims (4)

[Claims] 1. In an optical disc device for optically reproducing or recording / reproducing a disc, an objective lens for focusing a laser beam on a recording surface of the disc, and the objective lens is moved to focus the objective lens on the disc. A moving mechanism to match the recording surface,
A disc is mounted on at least two types of discs having different heights of the recording surface from the light incident / exiting surface of the disc, the disc including at least a movement amount detection circuit for detecting the movement amount of the objective lens moved by the movement mechanism. When performing the focusing operation of the objective lens by the moving mechanism in order to read the contents of, by detecting the moving amount of the moving mechanism during the focusing operation by the moving amount detection circuit,
An optical disk device characterized by detecting the position of a recording surface of a disk and discriminating between two or more kinds of disks having different recording surface heights. 2. The method according to claim 1, wherein two or more types of discs having different heights of the disc recording surface are provided with two or more objective lenses that match each other, and based on the disc type discrimination result. Then, the optical disk device is characterized by performing reproduction or recording / reproduction by switching to an objective lens suitable for the type of the disk. 3. The drive amount or drive current applied to the moving mechanism of the objective lens according to claim 1, wherein the moving amount detection circuit detects
An optical disc apparatus, wherein the disc is discriminated by detecting the difference in the height of the recording surface of the disc by using the relationship between the drive voltage or drive current and the movement amount. 4. The focus detection circuit according to claim 1, 2 or 3, comprising a focus detection circuit for detecting that the objective lens is in focus from a signal read from the recording surface of the disc, and the disc is mounted to read the contents of the disc. Therefore, when performing the focusing operation of the objective lens by the moving mechanism,
An optical disk device, wherein the amount of movement of an objective lens is detected by the movement amount detection circuit, and when the focus detection circuit detects that the objective lens is in focus, the disc type is discriminated.