JPH02173935A - Optical disk and optical disk recording and reproducing device - Google Patents

Abstract

PURPOSE:To stably detect a tracking error signal and to easily constitute a tracking servo circuit by providing an optical disk with a tracking bit string of different frequencies for tracking. CONSTITUTION:Two sets of tracking bit strings 4 and 8 with different frequencies are provided so as to sandwich a recording track 6. One light beam detects the tracking bit strings 4 and 8, and the difference in the reproducing level of the two tracking bit strings is taken by using a frequency difference, whereby the position of the light beam is found to perform tracking servo. The tracking servo strings are made intermittent, so that they do not sandwich an information signal track for recording information signals from both sides. The tracking bit strings are irradiated with one beam to detect the central part of the two tracking bit strings, and therefore the information signals can be recorded and reproduced while the light beam is tracking the recording track provided on the central part of the two tracking bit strings.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disc and a recording/reproducing apparatus thereof, and particularly to a tracking means thereof.

2. Description of the Related Art In order to efficiently record information signals on a recordable optical disc, an optical disc is provided with a pre-group, and the information signal is recorded by a light beam while scanning the pre-group. In order to scan the pre-group of an optical disk with a light beam, a far field method or a sunfull tracking servo method using wobble pits has conventionally been used as a tracking method. In the far field method, an offset may occur in the tracking error signal, and in the sample tracking servo method, the control circuit is complicated and the servo band is limited, and both have drawbacks. (For example, Tokuko Sho 59-1877
(Japanese Patent Publication No. 1, Japanese Patent Publication No. 63-43812, etc.) The present invention improves these points, and provides an optical disc that can stably detect a trunking error signal and relatively easily configure a tracking servo circuit, and provides an optical disc for recording and reproducing the same. The purpose is to provide a device.

Means for Solving the Problems In order to achieve the above object, in the optical disc of the present invention, instead of the pre-group, two tracking pit rows having different frequencies are provided with a recording track sandwiched between them.
These two tracking pit rows are detected with one light beam, and the difference in the reproduction level of the two tracking pit rows is determined by using the difference in frequency to determine the position of the light beam and perform nine tracking servos. There is.

In this case, in order to minimize the influence of the tracking pits on the information signal recorded on the recording track, the tracking pit row is made intermittent, and trunking is performed on the information signal track that is not intended to record the information signal. This prevents pit rows from being wedged in from both sides.

That is, for one information signal track, tracking pits with a period T1 are present on the right side in one section, and tracking pits with a period T2 are present on the left side in the next section.

Effect As described above, the optical disc of the present invention is provided with two tracking pit rows having different frequencies intermittently, so the center of the two tracking pit rows is detected by irradiating the tracking pit row with one beam. This makes it possible to record and reproduce information signals while tracking a light beam onto a recording track provided at the center of two tracking pit rows.

Embodiment FIG. 1 shows a block diagram of an optical disc according to an embodiment of the present invention, and FIG. 2 shows a block diagram of a tracking servo system of a recording/reproducing apparatus using this optical disc.

In Figure 1, 1 is an optical disc, track L
, , has L2. Figure 1 B beam.

It is an enlarged view of the track portion of L2, and is configured such that a tracking pit row 4 having a period of 1 and a tracking pit row having a period T2 alternately sandwich address pits 6 and information signal recording sections 9. Tracking pit rows 4, 6.
8, their period changes as T+ l T21 and + every round. Address signals indicated by 5 and 7 are indicated by arrow 1.
ID that displays when there is a tracking pit row with period T1 on the left side of the address pit when viewed from direction 1.
has.

For example, when the address signal indicates a track address, it can be determined that the period of the left tracking pit is T1 when the address signal is an odd address.

In this case, for example, the track pinch may be 1.6 microns, the tracking pit width may be 0.2 microns to 0.3 microns, and the address pit width may be approximately 0.3 microns.

Further, the depth or height of the tracking pit and the address pit can be set to 174 n Xλ, but of course, other values may be used. (Here, n is the refractive index of the protective substrate of the optical disc, and λ is the wavelength of the laser beam.

) A method for recording and reproducing information signals using the optical disc configured as described above will be described below.

FIG. 2 shows a block diagram of one embodiment of the invention.

In FIG. 2, 30 is the optical disc shown in FIG.
Rotation is controlled by a motor 31. 32 is a laser, which is converted into parallel light by a collimator 33, and a half mirror 3
4, the recording film of the optical disk 3Q is irradiated with a laser beam by the objective lens 36.

The light reflected by the optical disk 30 is transmitted to the half mirror 34.
After being reflected by the photodetector 36, converted into an electric signal by the photodetector 36, and amplified by the preamplifier 38, the reproduced signal of the tracking pit train having a period T+lF2 is passed through the BPF (band pass filter) 39. Here, the period T
The frequency at which the j+T2 tracking pit train is reproduced (assumed to be F1+F2) is set outside the frequency band of the signal recorded in the information signal recording section. In this example, Fl.

F2 was set at 5 M and 5.1 MHz. Also, the period for intermittent tracking pits is as follows:
It is set to 8.6μ.

Accordingly, BPF39 is s, o MHz, 5. I M
Both components of l-1z are passed. 40.41 is a balanced modulator which outputs each excavator 42.43 and BPF3.
The outputs of 9 are balanced modulated and input to BPF 44.46, and each output is sent to envelope detector 44-1.

The reproduced amplitude is detected at 45-1 and input to the differential amplifier 46 via sample and hold circuits 44-2 and 45-2. BPF44. BPF46 is ±100kl (z
It is a bandpass filter with a passband of .

47 is an equalizer that makes the response of the tracking servo system appropriate. A switch 48 is controlled by the controller 63, and changes the polarity of the trunking servo system depending on whether the inverting amplifier 49 is inserted or not. Reference numeral 50 denotes an adder, which is configured to be able to add the track jump pulses of the output 54. Reference numeral 51 denotes a drive amplifier that drives the trunking drive device 37 and operates so that the amplitudes of the two input signals of the differential amplifier become equal. Reference numeral 52 denotes an address signal reader that reads the address signal of the optical disk 30 and inputs it to the controller 53, which controls the jump pulse generator 54 and switch 48.

Reference numeral 66 denotes an information signal input terminal, which passes through the encoder 56 and attenuates the frequency components of F, .

Here, to attenuate the frequency of Fj + 22 is
This is to prevent the recording signal from being mixed into the reproduction signal of the tracking pit during recording.

eo determines whether the laser 32 is in the recording state or in the reproducing state. 61 is a track jump control input, which is used by the track jump generator 5 when performing a track jump.
A track jump pulse is output to the output of 4.

Next, the operation will be explained.

First, after the objective lens 36 is properly focused on the recording surface of the optical disc 30 (the focusing system is not shown), the frequency components of Fj + F2 appearing at the input of the differential amplifier 46 are equal. The tracking drive device 37 is controlled so that the That is, the component of the frequency F++'2 of the reproduced signal of the tracking pit train appearing on the photodetector 36 is amplified by the preamplifier 38, and then passed through a BPF (band pass filter) that passes the frequency component of F1+F2, and is balanced modulated. 40.41. The oscillation frequency of the oscillator 42 is 5.0MHz,
41 has an oscillation frequency of 5.1 MHz.

Therefore, frequency components converted to 100 KHz appear in the outputs of the balanced modulators 40 and 41, and the reproduced output of the tracking pit row 'I+ 22 is selectively separated by the BPF 44.45, and envelope detection is performed. Each level is detected by the detector 44-1.45-1. Envelope detector 44-1.45-
Since the output level of 1 becomes a burst signal, after each peak value is detected by the sample-and-hold circuit 44-2 and 46-2, the amplitudes are compared by the differential amplifier 46.

The output of the differential amplifier 46 is a so-called tracking error signal, and the output of the equalizer 47 . Switch 48° inverting amplifier 4
9. Adder 60. A tracking servo system is established by controlling the tracking drive device 37 via the drive amplifier 61.

As can be seen from FIG. 1, the tracking pit array having a reproduction frequency of '1+22 for the information signal recording section is divided into left, right, and left as viewed from the direction of arrow 11 every rotation of the optical disc 1. Because of this, the polarity of the tracking servo system is switched every round. By doing this, tracking servo can be achieved continuously even when the Lj+L2 track is in a spiral shape.

In this embodiment, when the address number of the address pit 6 is an odd number, the tracking pit row F1 is located on the left side when viewed from the address pit in the direction of the arrow 11, and the tracking pit row F2 is located on the right side.

reading the address number by the address reader 52 and controlling the switch 48 via the controller 63;
This allows tracking servo to be performed on either track having an odd or even address number.

When a control signal is applied to the track jump control input terminal 61, the controller 53 causes the track jump pulse generator 54 to apply a track jump pulse to the adder 50, and at the same time, disables the switch 48 to track the same circulating track.

When recording an information signal in the information signal recording section, the information signal 56 is processed/encoded by the encoder 66, and then at least the frequency components of F1 and F2 are cut off in the filter 6 and input to the laser modulator 59. Modulate the laser beam 32. By doing so, it is possible to prevent false signals from being mixed into the output of the differential amplifier 46.

Switching control between recording and playback is performed by the R/P control input 60. During recording, the output light of the laser 32 is modulated according to the signal to be recorded, and its output intensity is also increased during playback, and during playback, the output light is increased. The intensity of light is reduced compared to when recording.

Next, the track jump operation will be explained in detail.

In Figure 3, Figure 3 is an enlarged part of Figure 1, To is the tracking pit row F2, 71 is the tracking pit row F1, and similarly, 72 and 76
indicates the tracking pit row F1, and 73 and 74 indicate the tracking pit row F2, respectively. (Corresponding to FIG. 1B, the frequency during reproduction of period T1 corresponds to 21. The same applies hereinafter to 1). 76 is the starting point of the first sector, track (L,) 81, ) rack (L2) 82
is divided into sectors, 77.79 is the first sector, 7
8°8o is the second sector. Each sector has a track address number pit and a sector number pit at the beginning.

FIG. 3B is a waveform diagram of the track jump pulse, and t
The pulse from l to tl shows positive polarity, and the pulse from tl to t3 shows negative polarity.

Next, its operation will be explained. The track jump operation in the block diagram of FIG. 2 will be explained using FIG. 3. Figure 3: The human track is spiral-shaped, and the track (
From the first sector of track (L,) 81 to the second sector, and at the beginning of the first sector of track (L2) 82, the track (L
, ) track jump back to the first sector of sl. At this time, the left and right sides of the tracking pit row '1+F2 are switched at the starting point of the first sector. Therefore, when the light beam scanning the track reaches the first sector 79, the track jump pulse shown in FIG. 3B is applied to the adder 6° to perform a track jump to the track L1.

As described above, since the tracking polarity can be switched by the track address number pit provided at the beginning of the sector, the tracking servo is activated immediately after reading the address signal of the first sector of each track. The polarity of can be changed in synchronization with the frequency F++'2 of the pit string.

The dynamic range of the tracking servo system of the present invention can be approximately twice as wide as that of conventional systems (that is, the polarity of the tracking error signal does not invert in the range between the tracking pits '1*F2, (The dynamic range can be wider than that of a field type tracking servo system), and there is no need to detect the track position from a tracking error signal and perform acceleration or deceleration during track jump.

Also, when searching for any track, you can know the address number of the track to be searched in advance.
By matching the polarity of the tracking servo to the polarity determined by the address number, the tracking servo pull-in can be made more stable and the search speed can be made faster than in the conventional method.

Furthermore, the depth of the tracking pit and address pit,
Alternatively, by making the heights different from each other, it is also possible to reduce interference between the tracking signal and the address signal. For example, the height or depth of the tracking pit can be set to 1/8n x λ, and the height or depth of the address pit can be set to 1/4n x λ (λ is the pit area of the laser beam used). (This is the effective wavelength at
.

Effects of the Invention As described above, in the present invention, by providing a tracking pit array with different frequencies for tracking on an optical disc, a tracking error signal can be detected with one beam and one photodetector, and the tracking error signal can be detected by one beam and one photodetector. The center can be detected stably.

Furthermore, the detection dynamic range of the tracking error signal can be expanded approximately twice as compared to the conventional method.

Tracking pit rows are still intermittently installed, but
Since the intermittent period can be made very short, the band of the tracking servo system is not limited.

Further, since the frequency of the tracking pit string for detecting the tracking error signal is set so as not to interfere with the signal to be additionally recorded, the tracking pit string can be provided continuously on the recording track. In addition, since two types of tracking pit periods are used and are provided alternately, there is no mutual interference such as the generation of beat signals between tracking pits. At the same time, we made the difference between the two frequencies of the tracking pit train a small value, but by performing balanced modulation with the oscillator output close to the two frequencies,
This has great effects, such as being able to easily detect the level difference between two frequencies.

[Brief explanation of the drawing]

FIG. 1 is a structural plan view of an optical disc according to an embodiment of the present invention and an enlarged view of a track containing an address signal. FIG. 2 is a block diagram of an optical disc recording/reproducing apparatus according to an embodiment of the present invention. 2 is an enlarged plan view of the vicinity of the sector in FIG. 1 and a schematic waveform diagram of a track jump pulse. FIG. 1... Optical disk, Ll, Ll... Track, 4.8... Tracking pit row with period T1, 6... Tracking pit string with period T2, 30 ...Optical disk, 32...Semiconductor laser, 35...Photodetector, 39...
BPF, 40.41...Balanced modulator, 42,
43...Oscillator, 44, 46...B
PF, 44-1.45-1...Envelope detector, 46...Differential amplifier, 4-...Equalizer, 48...Switch, 49...・・・・・・
Inverting amplifier, 50... Adder, 61...
・Drive amplifier, 3rd place... Trunking drive device. Name of agent: Patent attorney Shigetaka Awano and 1 other person 30
- Multi [item f2] H-1 motor jf-L-b Jj--] I-ta

Claims (7)

[Claims] (1) Tracking pit rows with a constant period are provided on both sides of a recording track that is intermittently scanned with a light beam so that the periods of the tracking pit rows are different, and at least an information signal is recorded on the scanned recording track. 1. An optical disc characterized in that an address information pit is provided to indicate an address section and an address of the section. (2) Tracking pit rows with a constant period are provided on the disk so that the periods of the tracking pit rows are different on both sides of a recording track that is intermittently scanned by a light beam,
The scanned recording track is provided with at least an information signal recording section and an address information pit indicating the address of the section, so that the difference in the amplitude of the reproduction signal of each of the tracking pit rows having different periods is constant. An optical disc recording and reproducing apparatus characterized in that it is provided with servo means for performing tracking servo. (3) The optical disk recording and reproducing device according to claim 2, characterized in that the cycle of the tracking pits is changed every rotation of the optical disk, and the address information signal pits include information that allows the arrangement of the tracking pits to be determined. Device. (4) When the playback frequencies of two tracking pits are F_1 and F_2, the playback output of F_1 and F_2 is F_1+f_0, F_2+f_0 or F_1-
By performing balanced modulation with the output of the frequency oscillator f_0, F_2-f_0, separating by a filter having a band of at least f_0, detecting each reproduction amplitude, obtaining the peak value of each amplitude, and comparing, the tracking error can be reduced. 3. The optical disc recording/reproducing apparatus according to claim 2, wherein the tracking servo is performed so that the tracking error signal becomes zero. (5) When searching the address information signal and information signal recording section of the optical disc, select the section to be searched in advance.
A search operation is performed by setting the polarity of the tracking servo, which is determined by whether the tracking pits of two types of periods on both sides of the track scanned by the light beam are located on the inner circumference or on the outer circumference. The optical disc recording and reproducing apparatus according to claim 2, characterized in that: (6) Claim 2 characterized in that during reproduction, the reproduction frequency of the tracking pit is set to be outside the frequency band occupied by the information signal recorded in the information signal recording section or to a frequency band that does not include the information signal. The recording/reproducing device described in . (7) The optical disc recording and reproducing apparatus according to claim 2, characterized in that the tracking pits are arranged so that they are not adjacent to each other except for the portions sandwiching the address pits.