JPS61126635A - Optical memory disc - Google Patents

Abstract

PURPOSE:To obtain a stable tracking detection signal to perform sure control by forming tracking detection signals different in frequency on both sides of an information recording track area as pit strings. CONSTITUTION:A groove 4 is provided along an information recording track area 7 along this area 7, and pits 8 and 9 are arranged along parts on both sides of the area 7, and the tracking detection signal having a frequency f1 is recorded as a pit string of pits 8 to constitute a detection track 10, and the tracking detection signal having a frequency f2 is recorded as a pit string of pits 9 to constitute a detection track 11. Information is recorded on and reproduced from the area 7 by a main laser beam 12, and signals are read out from and traced on tracks 10 and 11 by sub-laser beams 13 and 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical memory disk in which information is recorded and reproduced optically, and particularly relates to an optical memory disk in which reliable track and king control can be easily obtained.

[Prior art]

Optical memory disks are equipped with an optical recording/reproducing film in which an optical recording medium is adhered in a thin film on one side of a disc-shaped transparent substrate, and a laser beam is irradiated onto this optical recording/reproducing layer according to the recorded information. By doing this, information is recorded by deforming or discoloring it into a pint shape, and during playback, reading is performed by taking advantage of the fact that the amount of light reflected from the readout laser beam against the recording track changes depending on the recorded information. . This optical memory disk has attracted particular attention in recent years because it can perform high-density recording by using a laser beam.

FIG. 4 is a plan view showing an example of an optical memory disk commonly used in the past. FIG. 5 is a sectional view of a main part of the optical memory disk shown in FIG. Here optical memory disk 1
The device has a disk-shaped substrate 2 made of a material that is transparent and has excellent heat resistance, and a central hole 3 into which a rotational coupling portion is fitted is provided at the center of rotation. Moreover, the surface of this substrate 2 has a depth T of 0.05-0.114 m,
Width W is 0.4-0.8 gm, pitch P is 1. S-2
, 81 J-m, recording track grooves 4 are provided in a spiral shape. And l1lI4 of this board 2
On the surface where is formed, an optical recording medium is adhered in a thin film form, thereby configuring optical recording and reproducing [5].
A protective layer (not shown) is provided on the back surface side.

In the optical memory disk configured in this way, the point v
As shown by a6, by irradiating the laser beam 6 modulated by the recorded information from the exposed surface side of the plate 1 and plate 2 along i44, the optical recording/reproducing [5 attached to this groove part] is formed into a pit shape. Recording information is recorded as a pit string by deforming or discoloring the pit. Furthermore, when reproducing recorded information, a reading laser beam is emitted along the groove 4 and the recorded information is read out using changes in the intensity of the reflected light, as in the case of recording.

In this case, what is important during recording and reproduction is to perform tracking control so that the laser beam is always located at the center of l+114. In this case, the tracking control detects the deformation due to the tracking deviation by receiving the reflected light of the laser beam used for 2 momme and reproduction, for example, 4 times, to detect the change in the light receiving pattern. R1 is performed using the difference component of the signals as a tracking error signal.

[Problem that the invention is trying to solve] However,
The optical memory disk with the above configuration uses a one-beam system that uses a single laser beam for recording and reproducing and detecting tracking errors. Therefore, when surface wobbling occurs due to the rotation of the optical memory disk, this surface wobbling causes the reflected light to change. This is because the light receiving pattern changes.

There is a problem in that the trunking error signal includes a component due to surface runout, making tracking control unstable.

[Specific means for solving the problem] In order to solve this problem, the optical memory disk according to the present invention has a pit array with tracking detection signals having the same frequency or A on both sides of the information recording track area. The information recording track and both tracking detection tracks are traced by independent laser beams.

[Effect]

In the optical memory disk configured in this way, the tracking detection tracks provided on both sides of the information recording track area are read by mutually independent laser beams, and the difference signal between the two track and king detection signals is read by the tracking knife. It can be used as a signal. and,
In this case, since the difference signal between the two tracking detection signals is used as the tracking error signal, the influence of surface runout of the optical memory disk is canceled and a stable tracking detection signal is obtained. This allows for reliable tracking control.

〔Example〕

1st rI! i is a sectional view of a main part showing a -χ embodiment of an optical memory disk according to the present invention, and the same parts as in FIG. 5 are designated by the same symbols and detailed explanation thereof is omitted. In the figure, reference numeral 7 denotes an information recording track area, and a groove 4 is provided along the information recording track area 7. 8.9
are pits arranged along both sides of the information recording track area 7, and a tracking detection signal of one frequency F is recorded as a pit string by the pits 8, thereby forming a first tracking detection track 10. A tracking detection signal of frequency f2 is recorded as a pit string of pits 9, thereby forming a second trunking detection track 11.

In the optical memory disk constructed in this manner, recording or reproduction of information in the information recording track area 7 is performed by the main laser beam 12, which is the same as the conventional one. The readout trace of the i2 trunking detection track 10.11 consists of two sub-laser beams 13.14 provided independently of the main laser beam 12.
Each is performed by Here, the reflected light when reading recorded information by the main laser beam 12 is received by the main light receiving section 15 shown in FIG. 2 via an optical system and output as a read signal.
The reflected lights of the sub laser beams 13 and 14 are respectively supplied to sub light receiving sections 16 and 17 via optical systems. The output signals of the sub light receiving sections 16 and 17 are respectively /<
After being amplified in sofa amplifiers 18 and 19, the signals are supplied to band pass filters 20 and 21, respectively.

In this case, since the passing frequencies of the bandpass filters 20 and 21 are set to f, , and r2, the output signal from the bandpass filter 20 detects the pit string of the first track/g detection track 10. F1 is output, and the bandpass filter 21 outputs an output signal F2 in which the bit string of the second tracking detection track 11 is detected. The output signals Fl and F2 of each of the bandpass filters 20 and 21 are sent to the detection circuit 22.
By being detected at ゜23, the first
．． Signals FD, FD2 are obtained which indicate the trace relationship of the sub-laser beam 13.14 with respect to the second tracking detection track 10.11.

Here, when the main laser beam 12 traces the center of the information recording track 7, the sub laser beams 13 and 14 are emitted from the first . 2nd tracking detection tracker 5ri 10
．． Slightly inside (or outside) the focus row at 11
Since their positional relationship is set so as to trace the first . These signals indicate the positions of the second tracking detection tracks to and tt, and change in opposite directions depending on the direction of tracking deviation. Therefore, in this case, the output signals FDI, F
D2 represents only the amount of tracking deviation, and the direction of the deviation cannot be known. Also, the output signal FD1. Since FD2 includes changes in the amount of reflected light due to vibration of the optical memory disk, it cannot be said to accurately represent tracking deviation or falsification.

For this purpose, the output signals FD, , F of the detection circuits 22 and 23 are
D2 is supplied to a differential amplifier 24, where the difference between the two is output as a tracking error signal TE.

In this case, if tracking is performed accurately, the levels of the output signals FD and FD2 will match, so the tracking error signal TE output from the differential amplifier 24 will act as an edge, causing tracking deviation. Since the level of the output signal FD or output signal FD2 increases depending on the direction and the level of the other signal decreases, the polarity of the tracking error signal TH indicates the direction of deviation, and the level of the tracking error signal TE indicates the direction of deviation. It will be expressed. The main laser beam 12 can accurately trace the information recording track area 7 by supplying a tracking error signal TE indicating the direction of tracking deviation and falsification to a tracking control circuit (not shown) to control the position of the optical head. can be done.

and.

In this case, the differential amplifier 24 outputs the output signal FD+
, FD2, the changes due to the surface runout of the optical memory disk included in both signals cancel each other out, and the tracking error signal TE becomes a signal that is not affected by the surface runout. Stable tracking control can be performed reliably.

Note that in the above embodiment, the first. :pJ2) Although the case has been described in which the frequency fife and f2 of the tracking detection signals recorded on the ranking detection tracks to and tt are made to be similar to each other, fl and f2 may be set to the same value,
In this case, it is necessary to match the passing frequencies of the bandpass filters 20 and 21 as well. Further, in the above embodiment, the case where the groove 4 is provided on the surface of the substrate 2 and the groove portion is used as the information recording track area 7 has been described.
It goes without saying that the invention may be applied to an optical memory disk that does not have grooves 4 as shown in the figure. In this case as well, the first. :B2) Racking detection truck 10.
Reference numeral 11 is provided in a biased portion of the predetermined information recording track area 7, that is, in a portion where there is no risk that the main laser beam 12 and the sub laser beams 13, 14 will trace an unintended track.

〔Effect of the invention〕

As explained above, in the optical memory disk according to the invention, bits are arranged along both sides of the information recording track area according to a predetermined frequency. Since the second tracking detection track is provided, a sub laser beam different from the main laser beam for tracing the information recording track area is used to detect the first tracking detection track. Since the second tracking detection track and track can be read independently from each other, by calculating the difference between the two read signals, the influence of the fluctuation of the optical memory disk is eliminated, and accordingly, the track and track 2 are stabilized. King control can be performed reliably.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing one embodiment of an optical memory disk according to the present invention, FIG. 2 is a block diagram showing a tracking error signal detection system, and FIG. 3 is a diagram showing another embodiment of an optical memory disk according to the present invention. 4 is a plan view showing an example of a conventional optical memory disk, and FIG. 5 is a sectional view of the main part of FIG. 4. 2... Substrate, 4... Groove 5... Optical recording and reproducing film, 7
... Information recording track area, 8, 9... Beef h,
I.Q. 11...Tracking detection track 12...Main laser beam, 13.14...Sub laser beam.

Claims (1)

[Claims] (1) An optical recording and reproducing film is formed by depositing an optical recording medium in a thin film on the surface of a disk-shaped substrate, and a laser beam modulated by the recorded information is applied to the information recording track area of this optical recording and reproducing film. In an optical memory disk, information is optically recorded by irradiating the information recording track area, and recorded information is read by changing the amount of reflected light of a reproduction laser beam irradiated to the information recording track area. An optical memory disk characterized in that first and second tracking detection tracks read out by mutually independent laser beams are provided along both sides, and tracking detection signals are recorded on the first and second tracking detection tracks.