JPH03269829A - Optical recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical recording/reproducing device, and particularly to a stable optical recording/reproducing device with little variation in gain of a tracking servo system or an autofocus servo system. It is.

[Prior Art] Optical disk devices have traditionally had the feature of being able to read and write data by replacing the optical disk as a recording medium. Therefore,
Conversely, it is necessary to construct a servo system that is stable against variations in disk characteristics.

As the tracking servo signal detection method of the conventional device, a light spot 5 is irradiated onto the guide groove 30 provided on the recording medium 3 in FIG. 2, and the reflected diffracted light is directed to the track center (the guide groove 30 in FIG. For the dash-dotted line shown),
It is common to extract the output difference between two symmetrically arranged photosensors.

However, the reflected signal from the guide groove 30 for tracking, that is, the output signal from the photosensor that detects the amount of deviation, is
, the reflectance of the recording film 4, the difference in laser power between playback and recording, and the pit 3 on the track during playback.
The amplitude of the tracking deviation signal fluctuates depending on the presence or absence of 1 and the sparseness and density of the pit arrangement, resulting in a problem that the tracking servo characteristics become unstable. Therefore, in order to improve this problem, as described in Japanese Unexamined Patent Publication No. 58-166541, during reproduction, the detection signal obtained from the reflected light from the recording medium is maintained at a high level by envelope detection. , to prevent the signal level from decreasing due to pits, and during recording, after low-pass filtering the detection signal obtained from the reflected light from the recording medium, AGC is applied to the summed signal of the reflected detection signal, thereby achieving high output recording power. This paper proposes a method to realize a stable tracking servo system by eliminating the influence of the increase in the level of the tracking control signal caused by the increase in the level of the tracking control signal.

[Problems to be Solved by the Invention] In the above prior art, the depth and width of the guide groove, the reflectance of the recording film, or the track pitch (in FIG. 3, the distance between the track centers of adjacent guides #h30) distance),
For multiple types of disks with different specifications such as data recording position (on-groove/groove recording), even if the incident power of the laser beam on the recording film is the same, the reflectance of one reflected light and the diffraction Because the directions are different, the detection sensitivity of the track deviation signal is different, the amplitude of the track deviation signal is different, and the characteristics of the track servo system fluctuate, making it unstable. The problem was that it was not possible to record and reproduce data on different types of discs.

Furthermore, according to the circuit configuration of the prior art invention, for each of the track deviation signal detectors A and H, at the time of reproduction,
An envelope detection circuit is required, and during recording, a low-pass filter circuit is required, in addition to that.

Since an AGC circuit is also required, the circuit scale becomes very large and the manufacturing cost increases accordingly.

The present invention aims to stabilize the tracking servo system by controlling and maintaining the different tracking servo signal detection sensitivities of various types of disks with different specifications at a certain constant value at high speed. The purpose is to enable recording and reproducing on a board, and to realize it with a relatively simple circuit configuration and low cost.

In addition, not only the tracking servo system but also the autofocus servo system, the reflectance of the recording film and the data recording film WF (
For multiple types of disks with different specifications such as on-groove/groove recording), track pitch, etc., even if the incident power of the laser beam to the recording film is the same, the reflectance of the reflected light is different, so conventional With this technology, the detection sensitivity of the defocus detection signal is different, and the amplitude of the detection signal is different, which causes the characteristics of the autofocus servo system to fluctuate and become unstable. Therefore, many types of discs with different specifications are used. However, it was difficult to record and reproduce data using the same device.

Therefore, another object of the present invention is to rapidly control and maintain the different defocus detection sensitivities of multiple types of discs with different specifications to a certain constant value, thereby stabilizing the autofocus servo system. , to enable recording and reproduction of many types of disks with different specifications.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a track deviation signal gain adjustment table that has a one-to-one correspondence with the types of disks with different specifications. Select the track deviation signal gain adjustment table corresponding to the type of disc to be recorded and reproduced from the table group.
A digital signal value corresponding to the sum of the detection signals of the track deviation detector is obtained from the table, and the track deviation signal is automatically gain controlled continuously and at high speed using this signal value.

In addition, in order to achieve the other object mentioned above, in the present invention, as many defocus signal gain adjustment tables are prepared as there are types of disks to be handled, each having a one-to-one correspondence with the types of disks having different specifications. , select a defocus signal gain adjustment table corresponding to the type of disc to be recorded and reproduced from the table group, find a digital signal value corresponding to the sum of the detection signals of the defocus detector from the table, Based on this signal value, the defocus signal is subjected to automatic gain control continuously and at high speed.

[Operations] The present invention provides a group of track deviation signal gain adjustment tables that correspond one-to-one to multiple types of discs with different specifications (track pitch, reflectance, guide groove depth and width, etc.). , a track deviation signal gain adjustment table is selected from among these according to the type of disc to be recorded and reproduced, and the gain of the track deviation signal is adjusted according to the magnitude of the sum signal of the track deviation detector that changes from time to time. Obtained from this table over time.

It performs high-speed automatic gain control on track deviation signals.

Regarding defocus signals, similarly to the above, the present invention prepares a group of defocus signal gain adjustment tables that correspond one-to-one to a plurality of types of discs with different specifications. Defocus signal gain adjustment table according to type,
Select one of these, use this table to find the gain of the defocus signal according to the thickness of the sum signal of the defocus detector that changes from time to time, and automatically gain the defocus signal over time at high speed. It can also be controlled.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 is a block diagram of a tracking servo system of an optical recording/reproducing apparatus showing an embodiment of the present invention. 1st
In the figure, 1 is a laser light source, 26 is an optical system, 2 is an objective lens, 3 is a disc-shaped recording medium, 4 is a recording film, 5 is a light spot irradiated on the disc-shaped recording medium, and 6 is a laser beam a tracking mirror that deflects the light spot 5 to move the position of the light spot 5 in the radial direction of the disc-shaped recording medium 3; 7 is a mirror wobbling coil that drives the tracking mirror 6; 8 detects the deviation of the light spot 5 from the track center; 10 is an amplifier for the track deviation detection signal 9, 11
12 is a subtracter; 12 is an adder; 14 is an A/D converter that converts the sum signal 13 of track deviation detection signals into a digital signal according to a high-speed clock 15; 33 is an A/D converter 1
4 output, 16 is a ROM storing a track deviation signal gain table group, 17 is the type of disk-shaped recording medium 3 currently being recorded and reproduced (differences in guide groove depth/width, track pitch, recording film reflectance, etc.) ) a corresponding table instruction signal that causes the microprocessor 24 to select the corresponding track deviation signal gain adjustment table from the table group in the ROM 16;
18 is the track deviation signal gain 20 obtained from the ROM 16
AG that automatically controls the gain of the track deviation difference signal 19 by
C circuit, 32 is a track position deviation signal after automatic gain control, 21 is a compensation circuit that improves servo characteristics, 22 is a power amplifier that amplifies the output of the compensation circuit 21 and drives the mirror pseudo-active coil 7, 28 is a compensation A power amplifier amplifies the output of the circuit 21 and drives the coarse actuator drive coil 27, 23 is an optical head equipped with an optical system, 25 is a spindle that rotates the disc-shaped recording medium 3 at a constant speed, and 29 is the optical head 23. This is a course actuator that moves the disk-shaped recording medium 3 in the radial direction.

Next, the operation of one embodiment of the present invention will be explained using FIGS. 1 and 3. The laser light emitted from the laser light source 1 passes through the optical system 26 and is directed to the tracking mirror 6.
The optical axis is deflected from the horizontal direction to the vertical direction, and the light is focused by the objective lens 2 to form a light spot 5, which forms a pit on the recording film 4 and records information. During reproduction, the recording film 4 is irradiated with a laser beam of lower power than during recording.

Data is read based on the strength of the opposite light depending on the presence or absence of information pits.

The light spot is formed by a guide groove 30 formed in a concentric spiral shape at equal intervals on the recording film 4 (see FIGS. 3(a) and 3(b)). The light spot is positioned with high precision on a track on the center line between the guide grooves 30 and records and reproduces information, and the tracking servo system controls the positioning of this light spot. This tracking servo system is based on the guide groove 3 of the recording film 4.
A pair of detectors 8 detect the deviation of the optical spot 5 from the track center by the reflected diffracted light from 0, the difference signal 19 is automatically gain controlled by the AGC circuit 18, and servo compensated by the compensation circuit 21. Course actuator 29
The optical spot 5 is controlled to be positioned at the center of the track by moving the tracking mirror 6.

Here, when the optical spot 5 crosses the guide groove 30 shown in FIGS. 3(a) and 3(b), the track deviation difference signal is as shown at 19 in FIG. 3(c) in the unrecorded area. In this case, since the amount of reflected light is large, the amplitude is also large, and the detection sensitivity is improved (V/μ
m) is also high, but in the green area described above, the amount of reflected light is small due to the pits 31, so the amplitude is small, and the detection sensitivity is also low.
, becomes smaller than 3, and the denser the pit arrangement, the more remarkable this tendency becomes. To explain this in detail according to Fig. 5, once the specifications of the disk (track pitch, shape and dimensions of the guide groove, reflectance, etc.) and head optical system are determined to be one type,
The track deviation sum signal S (13 in Fig. 1) and the track deviation detection sensitivity have an almost linear (proportional) relationship, and the straight line K
It becomes a. Let S be the track deviation sum signal and the detection sensitivity in the unrecorded area during reproduction, and use this as the design point. On the other hand, in the recorded green area during playback, the amount of reflected light per unit decreases due to the pits, so the track deviation sum signal is S2 (when the pit array is sparse), S, (when the pit array is dense). and 8
It becomes smaller than 1, and the detection sensitivity also becomes smaller than , K, and □. Conversely, during recording, since the laser power increases, the amount of reflected light also increases, and the track deviation sum signal becomes S4, which is greater than S□, and therefore the detection sensitivity also increases. Therefore, in order to control the detection sensitivity K to a constant value of 1 regardless of fluctuations in the amount of reflected light, it is necessary to obtain the current track deviation sum signal Sx and multiply the track deviation difference signal by S, /Sx. . Therefore, TR8SCOMP=TR5S o X 51/ S X
..."" (1) However, TRS S COMP: Track position deviation signal after automatic gain control (32 in Figure 1) TR3S: Track deviation difference signal before automatic gain control (19 in Figure 1) The relationship is established, and the gain Ga of the AGC circuit 18 is set as Ga=S.
Engineering/S x・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・(2), that is, because Sl is a constant.

The gain may be controlled so that it is inversely proportional to Sx, which changes from moment to moment. On the other hand, if the type of disk is different.

Since the manner of reflection and diffraction by the guide groove and the recording film are different, the relationship between S and K is like that of Kb and Kc, which have different slopes from Ka. For example, in the case of Kb, when compared with Ka, the detection sensitivity for the same Sx is 6 for the straight line Ka and 6 for the straight line Kb, and K,>K.
Since the straight line Kb has a higher sensitivity, in order to have the same sensitivity as the straight line Ka, it is necessary to multiply equation (2) by Ca/Cb.

That is, let Gb be the gain in the case of a disc specification with a detection sensitivity straight line of Kb.

Gb=S Eng/S x X Ca/Cb...
・・・・・・・・・・・・(3) However, Ca: Straight line Ka
Gradient Cb: The gain may be controlled so as to have the slope of the straight line Kb.

Therefore, the relationship shown in FIG. 6 is established between the track deviation sum signal S and the gain G (the curve Ga is Ka in the tJ5 diagram).
, Gb corresponds to Kb, and Gc corresponds to Kc).

A group of gain tables as shown in Fig. 6, which correspond one-to-one to the types of discs to be handled, are registered in the ROM 16 shown in Fig. 1.
At the time of initial setting after inserting the disk, the microprocessor 24 generates a corresponding table instruction signal 17 to select a gain table (for example, Ga) corresponding to the type of the disk.

After that, the track deviation sum signal 13, which changes from moment to moment, is
A/D conversion is performed according to the high-speed sampling clock 15, and the gain Gp (20 in FIG. 1) corresponding to the digital value op (33 in FIG. 1) is stored in the ROM 16, and a gain table Ga ( Figure 6), A
The GC circuit 18 performs automatic gain control on the track deviation difference signal 19.

According to this embodiment, by storing in advance in the ROM 16 a large number of track deviation signal gain adjustment tables in one-to-one correspondence with the types of discs to be handled, it is possible to handle many types of discs stably and without gain fluctuations. Recording and reproducing can be performed using a small tracking servo system, and the circuit scale is small and the cost can be reduced.

Next, AGC circuit 1 realized by ladder resistance switching method
8 will be explained with reference to FIG.

The AGC circuit 18 includes eight weighted ladder resistors R in parallel with a fixed resistor R, which are externally connected to the operational amplifier 34.
, R work (=R, /2) , ..., R7=(R,
/27), and the gain of the AGC circuit 18 is controlled by switching the analog switches AS0 to AS, respectively, using the output bits b6 to b7 of the ROM 16 to change the external combined resistance value. If the output value of ROM16 is DROM, D8° y = b, +21b y +
・・・・・・+27b7・・・・・・・・・(4) However, b, -b7 are binary values of O or 1. Also, operation increase @WF
If the external resistance value of 34 is Z, then RRo R0/2 K0/1RR.

R.R.

Therefore, the gain G of the AGC circuit 18 is γ γ Re
10R" D a.2 Also, if the input upper limit setting value of the A/D converter 14 is vT, the lower limit setting value is 1, and the input value is Vi, the relationship between the input Vi and the output DAD is as shown in FIG. It becomes like this.

Assuming that the number of conversion bits is 8 bits, if Vi is smaller than ■3, DAD remains at the minimum O, and if Vi is larger than vT, DA! + is the maximum value of 255, and between V n < V t < V T 1', a linear relationship is established between Vi and DAD. The summing amplifier 12 multiplies the sum of the track deviation signals Va and vb to obtain a track deviation sum signal 36, and the level conversion amplifier 35 adds vl to raise the level for input to the A/D converter. I do. From the above, V i = K (V a + V b ) + V
B...................................................(7) holds true. Therefore, according to FIG. 8, between the input and output of the A/D converter, (1) DAl when Vi<VB, 20(2) V B:ii;
Vll VT Vm・・・・・・
・・・・・・・・・・・・(8)(3) V c > V
In the case of T, the relationship DAD=255 holds true. As here, Dit. Also set M. However, k=C
a/Cb, and Ca and cb are the values in equation (3). Therefore, the relationship between DIl(+2 and I)Ao is the 9th
As shown in the figure, Ta corresponds to Ka, Tb to Kb, and Tc to Kc in FIG. Substituting equation (8) into equation (9), k VT-VB Substituting equation (10) into equation (6), VT-V.

255γK Va+Vb However, if Rotγ and K are selected so that S x = Va + V b, the same relationship as in equation (3) is established, and the desired gain control is concretely realized.

Also, as shown in Figure 4, there is a defect on the disk.

Even if the amount of reflected light becomes extremely small and D, 1°2 = 0, from equation (6), G = -1 γ, and a limiter is applied to prevent G from becoming infinite. There is.

Next, another embodiment of the present invention will be described with reference to FIG. 1o. Since the configuration is the same as that in FIG. 1, only the different parts will be explained. Figure 10 is.

It is a block diagram of the autofocus servo system of the optical recording and reproducing device, in which 34 is a coil that drives the objective lens 2, 35 is a defocus detector, 36 is a defocus detection signal, 37 is an amplifier, 38 is an adder, 39 is a subtracter, 40 is an AGC circuit for the focus shift difference signal 43, 41 is a compensation circuit for the automatic focus shift signal 44 after automatic gain control, and 42 is an amplification circuit for amplifying the output voltage of the compensation circuit 41 to output the objective lens drive coil 34. This is a power amplifier that drives the.

The operating principle of this embodiment is the same as that of the embodiment shown in FIG. 1, so the explanation will be omitted.

In this embodiment, the type of disc to be handled and one
By storing a large number of defocus signal gain** tables that correspond to 1 to 1, it is possible to record and reproduce many types of discs using an autofocus servo system that is stable and has little gain fluctuation.
The circuit scale is small.

It has the effect of being inexpensive.

[Effects of the Invention] According to the present invention, disc-shaped recording media with defects on the disc surface, and multiple types of disc-shaped recording media with different specifications such as guide groove shape and size, track pitch, recording film reflectance, etc. It is possible to gain control the different track deviation detection sensitivities or defocus detection sensitivities to a certain constant value, so a stable track servo system or autofocus servo system with little gain fluctuation can be used to Recording and reproduction can be performed on a recording medium, and this can be achieved with a simple circuit configuration and low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a tracking servo system of an optical recording/reproducing apparatus showing one embodiment of the present invention, and No. 21! 1 is an external view of a guide groove of a disk-shaped recording medium, and FIG. 3 is a diagram showing the relationship between pits and track deviation signals. Fig. 4 is a diagram showing a disk defect in a disc-shaped recording medium, Fig. 5 is a diagram showing the relationship between track deviation sum signal and track deviation detection sensitivity, and Fig. 6 is a diagram showing the track deviation sum signal and track deviation difference signal. 7 is a diagram showing an example of the AGC circuit, FIG. 8 is a diagram showing the input/output relationship of the A/D converter, and FIG. 9 is a diagram showing the relationship between the A/D converter output and the ROM. FIG. 10 is a block diagram of a tracking servo system of an optical recording/reproducing apparatus showing another embodiment of the present invention. l...Laser light source, 2...Objective lens, 3...Disc-shaped recording medium, 4...Recording film, 6...Tracking Mirror, 7...
・Mirror driving coil, 8...Track deviation detector, 10...Amplifier, 11...Subtractor,
12...Adder, 14...A/D converter. 16...ROM, 18...AGC circuit,
21... Compensation circuit, 22... Power amplifier, 23... Optical head, 24... Microprocessor, 25... Spindle, 26
...Optical system 527...Coarse actuator drive coil, 28...Power amplifier, 2
9...Coarse actuator. 30...Guide groove, 31...Pit. Kugo diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram diagram fig. diagram diagram fig. fig. fig. fig. fig. fig. Fist 1, Kav1

Claims (1)

[Claims] 1. In an optical recording and reproducing device that records and reproduces information by irradiating a light spot onto or between the guide grooves of a disc-shaped recording medium, the light spot emitted from the guide groove is A track deviation detector for detecting deviation, an adder for generating a sum signal of the track deviation detector, and a magnitude of the sum signal in one-to-one correspondence for a plurality of types of disks with different specifications, It has a plurality of signal conversion tables that convert into digital signal values according to a certain rule, and an AGC circuit that automatically controls the gain of the light spot deviation detection signal, and when the disc is inserted, it After selecting a corresponding table, a digital signal value corresponding to the magnitude of the sum signal that changes from moment to moment is obtained from the signal conversion table, and the signal value is used to convert the AG
An optical recording/reproducing device characterized in that the gain of a C circuit is controlled continuously at high speed. 2. The optical recording/reproducing apparatus according to claim 1, wherein the A
As a GC circuit, the gain is automatically controlled by switching one fixed resistor connected externally to the operational amplifier in parallel and a plurality of parallel ladder resistors, respectively, according to the output of the signal conversion table. An optical recording and reproducing device. 3. In an optical recording and reproducing device that records and reproduces information by irradiating a light spot onto the recording film of a disc-shaped recording medium,
a defocus detector for detecting a defocus of the light spot from the recording film; an adder for generating a sum signal of the defocus detector; and a plurality of types of circles with different specifications for determining the magnitude of the sum signal. It has a plurality of signal conversion tables that correspond to each board one-to-one and converts into digital signal values according to a certain rule, and an AGC circuit that automatically controls the gain of the defocus detection signal. After selecting the table corresponding to the type of disc when inserting the board, a digital signal value corresponding to the magnitude of the sum signal that changes from time to time is obtained from the signal conversion table, and the signal value is used to convert the AGC circuit. An optical recording/reproducing device characterized by continuously controlling gain at high speed.