JPH0426921A - Optical disk device - Google Patents

Abstract

PURPOSE:To unnecessitate a sensor for detecting a discrimination mark or the discrimination switch of a cartridge, etc., by detecting the presence or absence of various information on a disk, level and read accuracy or the like through a pickup. CONSTITUTION:An RF signal outputting from a pickup 13 is inputted to a BPF (Band Pass Filter) 31 so as to detect an address signal included in the RF signal. The detected address signal is inputted through a gate circuit 32 to a latch circuit 33, and an H/L signal is outputted at timing for switching the polarity of tracking control. Then, the control polarity of a tracking servo circuit 16 is switched. Thus, it is not necessary to provide the sensor and the switch or the like for discriminating the type of the disk.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for recording signals on an optical disk (hereinafter simply referred to as a disk) having a signal recording track called a concavo-convex pre-group, or for reproducing a signal from a disk. The present invention relates to an optical disc device.

2. Description of the Related Art In recent years, optical disc devices such as CDs, video discs, and writable document files, data files, and image files have become popular. In such an optical disc device, a light beam from a semiconductor laser or the like focused to a diameter of about 1 μm is irradiated onto the disc to record or reproduce signals.

Generally, a disk is provided with tracks having various shapes such as pits, concave and convex shapes, or a mixture of both, and are arranged concentrically or spirally at a pitch of about 1.6 μm. The focus servo works so that the light beam spot, which is narrowed down to a diameter of about 1 μm, is always focused on the track even when the disc is rotating, even if the disc is eccentric. The tracking servo works so that the light beam spot follows. The light beam is transmitted from a pickup consisting of optical blocks such as photoelectric conversion elements and electrical circuits necessary for recording and reproducing signals, lenses for shaping the light beam, and an actuator block for moving the optical axis of the light beam. The light is emitted through an objective lens for focus servo.

Now, in such an optical disc device, when the track shapes of the discs are different as described above, it is desirable to have compatibility between the discs so that they can be used in the same optical disc device.

Therefore, a method of ensuring compatibility with conventional discs having uneven tracks that can be recorded and reproduced using basically the same pickup will be explained.

FIG. 4(a) shows an example of a disc in which a disc identification mark 2 is provided in advance on the inner circumference of the disc 1. When such a disc 1 is rotated within an optical disc device, it is read by a sensor that detects the disc discrimination mark 2, and the track shape and signal recording state of the disc 1 are determined. In addition, Fig. 4(b) shows that the disc identification mark 2 is not present (but the cartridge 3 containing disc 1 is
A disc discrimination switch 4 is attached to the disc 1, and this switch 4 is used to discriminate the type of disc 1.

FIG. 5 shows an example of an optical disc apparatus for recording and reproducing the disc 1 having the disc discrimination mark 2 shown in FIG. 4(a). The disk 1 is rotationally driven by a disk motor 5.

The light beam emitted from the objective lens 7 in the pickup 6 is controlled by a tracking servo circuit 8 so that the light beam spot always follows the track of the disk 1. Furthermore, the output of the disc discrimination mark detection sensor 9 is applied to a polarity discrimination circuit 1°, which determines whether the track to be recorded or reproduced is concave or convex. is applied to. The tracking control error signal is obtained by receiving the output from the divided optical detector in the pickup 6 with a differential amplifier.By switching the signal and changing the polarity before taking the differential signal, the optical beam is The following track of the spot can be switched from a convex track to a concave track, or from a concave track to a convex track. The above-mentioned device is, for example,
This is explained in, for example, Japanese Patent No.-57859.

Problems to be Solved by the Invention As described above, conventionally, in order to make a disc with a concave recording/reproducing track compatible with a disc with a convex recording/reproducing track, the type of the disc or cartridge must be determined in advance. It was necessary to provide identification marks and switches for this purpose. Furthermore, the optical disc device requires a detection sensor and a switch, which makes the device expensive and has a complicated structure.

In view of the above-mentioned problems, the present invention is inexpensive, highly reliable,
The object of the present invention is to provide an optical disc device that is compatible with discs.

Means for Solving the Problems In order to achieve the above object, the present invention includes means for detecting the presence or absence or level of an address signal provided in advance on a disk, a recorded information signal, etc. via a pickup, The polarity of tracking control is switched depending on the presence or absence or level of a signal or information signal.

Effect of the present invention With the above-described configuration, the present invention is equipped with means for detecting the presence or absence or level of an address signal or recorded information signal, thereby eliminating the need for sensors, switches, etc. for identifying the disc type, and making it easier to identify the disc type. It becomes possible to discriminate even discs without marks, and it is possible to realize an optical disc device that is inexpensive, highly reliable, and compatible with discs.

Embodiment FIG. 1 is a block diagram showing the main parts of an optical disc device in an embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a disk having uneven signal recording tracks, 12 a disk motor for rotationally driving the disk 11, and 13
14 is an objective lens in the pickup 13, and 15 is a pickup for irradiating a light beam onto the disk 11 to record and reproduce information signals such as images. A focus servo circuit 16 drives and controls the objective lens 14 so that the optical beam spot focused on the signal recording surface of the disk 11 follows the signal recording track on the disk 11 by the focus servo circuit 15. 17 is a tracking servo circuit that drives and controls the objective lens 14;
A signal detection circuit 18 detects the presence or absence or level of a signal recorded in advance on the signal detection circuit 17, and a signal detection circuit 18 controls the control polarity of the tracking servo circuit 16 by the output of the signal detection circuit 17 so that the tracking track of the light beam spot changes from a concave track to a convex track or This is a polarity changeover switch that switches from a convex track to a concave track.

FIG. 2 is a block diagram of the main parts of the tracking servo circuit 16 in one embodiment of the present invention. , In FIG. 2, 19 is an optical detector in the pickup 13, 20 is a one-pole tracking error signal output from the optical detector 19, 21 is a chishu tracking error signal, 18a,
18b is a polarity changeover switch, 22 is a differential amplifier, 2
3 is an equalizer, 24 is a drive amplifier, and 25 is a tracking actuator that drives the objective lens 14 in the pickup 13 to perform tracking.

Next, the operation of the above embodiment will be explained. In FIGS. 1 and 2, a disk 11 is rotationally driven by a disk motor 12, and a light beam emitted from an objective lens 14 in a pickup 13 is reflected by the disk 11, and this reflected light is transmitted inside the pickup 13. enters the divided optical detector 19, and the output of the optical detector 19 is
The tracking error signal 20.21 enters the tracking servo circuit 16, and the tracking servo circuit 16
The output is again applied to the tracking actuator 25 inside the pickup 13 to drive the objective lens 14 so that the light beam from the pickup 13 correctly follows the signal recording track. A focusing error signal is also output from the optical detector 19 in the pickup 13 and input to the focus servo circuit 15, and the output from the focus servo circuit 15 drives the objective lens 14 to focus on the signal recording surface. .

In FIG. 2, the output of the divided optical detector 19 in the pickup becomes a -polarity tracking error signal 20 and a thousand-wave tracking error signal 21, which are passed through polarity changeover switches 18a and 18b to a differential amplifier 22.
is input. The output of the differential amplifier 22 is the equalizer 2
3. The signal is applied to a tracking actuator 25 in the pickup via a drive amplifier 24, and drives the tracking actuator so that the light beam spot follows the track. Further, the output of the signal detection circuit 17 is applied to polarity changeover switches 18a and 18b.
The human input signal of the differential amplifier 22 is switched depending on whether there is a detection signal or not, and the tracking track of the light beam spot is switched from a concave shape to a convex shape or from a convex shape to a concave shape. In this case, the tracking control polarity changeover switches 18a and 18b are set in advance to have either polarity, and after the signal detection circuit 17 detects the presence or absence of the signal or the level at a predetermined timing, the tracking control polarity changeover switches 18a and 18b are set to have either of the polarities. Switch the polarity so that the light beam follows the track.

FIG. 3 shows a specific configuration example of the signal detection circuit 17 that detects the presence or absence of a signal or its level.
) is the first example. In FIG. 3(a), the RF signal output from the pickup 13
Double signal, BPF (Band Pa5s Filter
) 3 l, detects the address signal included in the RF multiplied signal, the detected address signal passes through the gate circuit 32, enters the latch circuit 33, and outputs the H/L signal in accordance with the timing of tracking control polarity switching. The control polarity of the tracking servo circuit 16 is switched.

FIG. 3(b) shows a second embodiment, in which the pickup 13
The RF multiplied signal outputted from the RF multiplied signal enters the BPF 34, and the information signal included in the RF multiplied signal is detected.The detected information signal passes through the detection circuit 35 and enters the comparator 36, determines the level of the information signal, and sets it to a predetermined level. An information signal presence/absence signal is output to the latch circuit 37 depending on whether the information signal is larger or smaller, and the latch circuit 37 outputs an H signal at the timing of tracking polarity switching.
/L polarity switching signal is output, and the polarity of the tracking servo circuit 16 is switched.

Further, FIG. 3(c) shows a third embodiment, in which the RF multiplied signal from the pickup enters the A/D converter 38, is taken into the microcomputer 39, and there is no dropout in the address signal or information signal. Even in such a case, it is determined whether a signal can be detected with a predetermined probability or higher, and the tracking polarity is switched accordingly. In this way, the RF multiplied signal A/
By importing the data into the microcomputer 39 using the D converter 38, it is possible to realize an optical disc device that is stable and highly reliable and compatible with discs not only in the presence or absence of address signals and information signals, but also in the presence or absence of signal dropouts.

Further, in the fourth embodiment shown in FIG. 3(d), after passing through the BPF 40 and extracting only the address signal component, the RF signal component is binarized by the comparator 41, and the RF signal outputted from the pickup 13 is processed by the address reading circuit 42. The address signal inside is read and the address, which is the position signal of the track currently being followed by the pickup 13, is sent to the microcomputer 43. The microcomputer 43 sets the tracking polarity at an appropriate timing (for example, every few rotations of the disk).
The tracking polarity of the tracking servo circuit 16 is determined by checking and detecting the tracking polarity that allows the address signal to be read accurately based on the connection between the previous and subsequent address signals and the error detection signal (CRC signal, etc.) included in the address signal. do.

As mentioned above, it is also possible to use a combination of the embodiments shown in FIGS. 3(a) to 3(d), and in the embodiments shown in FIGS. 1 and 2, it is possible to Although described above, it is also possible to apply the present invention to optical recording media having uneven tracks, such as optical cards and optical tapes.

Furthermore, tracking polarity switching is performed by the differential amplifier 22.
Although this has been realized by switching the input signal polarity, it is also possible to realize it by inserting a polarity switching circuit at an appropriate position within the tracking servo circuit 16. Also,
The gate circuit 32, latch circuits 33, 37, etc. shown in the embodiments (a) and (b) in FIG. 3 are used in the embodiment shown in FIG. 3(C) in order to realize a more advanced judgment function and control function.

It is also possible to implement the microcomputer 39 or 43 shown in (d).

It goes without saying that the appropriate timing for switching the tracking control polarity is when the optical disc device is started.

Effects of the Invention The optical disc device of the present invention configured as described above detects the presence or absence of various information on the disc, its position, reading accuracy, etc. through the pickup, and detects whether the light beam has to follow. Not only can discs with concave or convex signal recording tracks be easily identified, but also discs with concave or convex signal recording tracks can be easily identified. This eliminates the need for a sensor for cartridges, a cartridge discrimination switch, etc., and the system is inexpensive and has a simple configuration, which has great effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of an optical disc device in an embodiment of the present invention, FIG. 2 is a block diagram of the main parts of a tracking servo circuit in an embodiment of the invention, and FIG. 3 is an embodiment of the invention. FIG. 4 is a block diagram showing a specific configuration example of the signal detection circuit in the example, FIG. 4 is a plan view showing a conventional disk discrimination method, and FIG. 5 is a block diagram showing a conventional example of an optical disk device. 11... Disc, 12... Disc motor, 13
...Pickup, 14...Objective lens, 15...
- Focus servo circuit, 16... Tracking servo circuit, 17-... Signal detection circuit, 18.18a, 18
b...Polarity changeover switch, 19...Optical detector, 20.21...Tracking error signal, 22...
- Differential amplifier, 23... Equalizer, 24... Drive amplifier, 25... Tracking actuator, 31
, 34.40... BPF, 32... Gate circuit, 3
3.37...Latch circuit, 35...Detection circuit, 36
... Comparator, 38 ... A/D converter, 39.4
3...Microcomputer, 41...Comparator, 42...Address reading circuit. Name of agent: Patent attorney Masahiro Kurago #! 1 Figure 11 Day Star Figure 4! JPJ5 diagram

Claims (4)

[Claims] (1) A rotational drive means for rotationally driving an optical disk having an uneven signal recording track, a pickup means for recording and reproducing information signals by irradiating the optical disk with a light beam, and an objective lens in the pickup means. a focus servo means for driving and controlling the objective lens so that the light beam emitted from the optical disk is focused on the signal recording surface of the optical disk; and a light beam focused on the signal recording surface of the optical disk by the focus servo means. tracking servo means for driving and controlling the objective lens so that the spot follows a signal recording track on the optical disk; and a signal for detecting the presence or absence or level of a signal pre-recorded on the optical disk detected by the pickup means. An optical disc device comprising: a detection means; and a polarity switching means for switching the control polarity of the tracking servo means according to the type of unevenness of the track followed by the light beam spot based on the output of the signal detection means. . (2) The optical disc device according to claim (1), wherein the signal detection means detects the presence or absence or level of an address signal recorded in advance on the optical disc. (3) The optical disc device according to claim (1), wherein the signal detection means detects the presence or absence or level of an information signal recorded in advance on the optical disc. (4) The optical disc device according to claim (1), wherein the signal detection means detects the presence, level, or reading accuracy of a signal recorded in advance on the optical disc with a predetermined probability.