JPH033121A - Optical disk recording and reproducing device - Google Patents

Abstract

PURPOSE:To automatically adjust the action of a focus at a focusing position and to make the action precise and stable by providing a focus error signal detection circuit, an addition circuit, an address signal detection circuit and a means which detects the amplitude level of the VFO of an address signal. CONSTITUTION:The means which detects the signal level of the VFO of the address signal is constituted of a VFO signal level detection circuit 12, a controller 14 or the like. Before executing servo control, the controller 14 outputs an offset voltage that focusing is executed to some degree to the addition circuit 8. After the target value of focusing being the output of the controller 14 is changed and added to the addition circuit 8 and two target values of the focusing that the amplitude level of the VFO of the address signal becomes the same are decided by the controller 14, the intermediate target value of two target values is added to the addition circuit 8 from the controller 14. As the result, the action of the focus at the focusing position is automatically executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disk recording and reproducing device for a large capacity data file device capable of high-density recording, erasing, and reproducing.

Conventional technology In recent years, optical disc recording and playback devices have become high-density recording devices.

It is being actively developed as a large-capacity data file device that can be erased and played back.

A conventional optical disc recording and reproducing device will be explained below.

FIG. 5 shows a block diagram of a conventional optical disc recording and reproducing apparatus. In FIG. 5, 1 is an optical disc. 2 is a light beam. 3 is an actuator.

4 is an optical head. 5 is a focus error signal detection circuit. 6 is a tracking error signal detection circuit.

7 is an address signal detection circuit. 8 is an adder circuit. 21 is a variable voltage source whose output can be changed by the value of a variable resistor or the like. 9 is a focus drive circuit. 10 is a tracking drive circuit.

The operation of the optical disc recording and reproducing apparatus configured as described above will be described below. The reflected light from the optical disc l output from the optical helix 4 is input to a focus error signal detection circuit 4, a tracking error signal detection circuit 5, and an address signal detection circuit 7. The focus error signal detected by the focus error signal detection circuit 5 is changed by the offset voltage of the variable voltage source 21 in the adder circuit 8, and is outputted to the focus drive circuit 9 as a focus target value.

The tracking error signal detection circuit 6 detects a tracking error signal and outputs it to the tracking drive circuit 10. With the servo applied, the focus drive circuit 9 and the tracking drive circuit 10 drive the actuator 3 to generate the light beam 2.
are converged to form an optical slot 7 on the optical disc 1. The address signal detection circuit 7 outputs an address signal from the output of the node 4 to the optical device. Here, the structure of the address signal will be briefly explained. The address signal is a sector mark, a synchronization pull-in pattern (Vari
able Frequency Oscillator
(hereinafter abbreviated as VFO), addresses, and are arranged as sector marks and VFOs.

Address 1, VFO, address 2 (the written content is the same as address 1). VFO is an address synchronization pull-in pattern, and the highest repetition frequency (
It is a single sine wave signal with the same repetition frequency as 1,57). The frequency characteristics of the address signal and the recording signal become maximum at the focal point position of the focus. Therefore, the point where the amplitude level of the VFO of the address signal is maximum is the in-focus position.

Conventionally, the output of the address signal detection circuit 7 is observed with an oscilloscope in the servo operating state, and the offset voltage of the variable voltage source 20 applied to the adder circuit 8 is changed so that the VFO level of the address signal is maximized to achieve focus. It was aligned to the focal point.

Problems to be Solved by the Invention However, the conventional configuration described above requires a process of adjusting the focus to the in-focus position, which may cause errors when measuring the signal level of the VFO at the address and variable resistance of the offset voltage of the variable voltage source. Due to instrument error, it is not possible to operate at a positive focal point position. Another drawback is that stable operation cannot be expected due to aging, temperature characteristics, etc. of the variable voltage source.

The present invention solves the above-mentioned conventional problems, and uses an analog-to-digital converter, V
By adding an FO signal level detection circuit, a control signal generation circuit, and a controller, and adding the output of the controller to the addition circuit that provides the focus target value, the operation at the in-focus position can be automatically adjusted. It is an object of the present invention to provide an optical disc recording and reproducing apparatus having a configuration that allows accurate and stable operation.

Means for Solving the Problems To achieve this object, the optical disc recording and reproducing apparatus of the present invention comprises an optical disc, a focus error signal detection circuit, an addition circuit, an address signal detection circuit, and means for detecting the amplitude level of the VFO of the address signal. It has the following configuration.

Function: With this configuration, it is easy to detect the VFO signal level of the address signal and automatically adjust it to the in-focus position.

Embodiment Hereinafter, an optical disc recording/reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of an optical disc recording/reproducing apparatus according to an embodiment of the present invention. In Figure 1, 1
is an optical disk, 2 is a light beam, 3 is an actuator, 4
5 is an optical head, 5 is a focus error signal detection circuit, 6 is a tracking error signal detection circuit, 7 is an address signal detection circuit, 8 is an addition circuit, 9 is a focus drive circuit, 10 is a tracking drive circuit, 11 is an analog-digital conversion 12 is a VFO signal level detection circuit, 13 is a control signal generation circuit, and 14 is a controller.

It should be noted that among the block nine elements used in the description of the conventional technology, those having the same functions are given the same numbers.

The operation of the block diagram of the optical disc recording and reproducing apparatus configured as described above will be described below.

Controller before applying servo! 4 outputs an offset voltage with a certain degree of focus to the adder circuit 8. The address signal of the address signal detection circuit 7 is shown in FIG.
Shown in a). The analog-digital converter 11 converts this output signal into a digital signal! ＾Do it. The control signal generation circuit 13 outputs "1" from the digital signal to the VFO signal level detection circuit 12 during the VFO section of the address signal (Fig. 3(b)). At this time, the VFO signal level detection circuit detects the VFO signal level. is calculated and the cumulative addition result for that section is output to the controller 14. Before applying the servo, the controller 14 outputs an offset voltage that provides a certain degree of focus to the adder circuit 8. After applying the servo, the controller 14 first changes the offset voltage applied to the adder circuit 8 to detect the VFO signal level detection circuit 12.
The output results of the VFO according to each offset voltage are stored (FIG. 4(a)). Next, Figure 4 (al's VFO
The offset voltage V, , V whose amplitude level is 13 dB
2, and determine the center value vo of the offset voltage of vl and ■2.
: By adding 1/2 (V, +V2) to the adder circuit 8, the operation is completed and the operation at the in-focus position is automatically performed. If this method is used, Figure 4 (a)
), the value of change in the offset voltage as VFO changes is small and there is a peak, but it also operates stably, as shown in Figure 4(b). Even if the peak of vFO is large and the peak of vFO is wide, the offset voltage is the midpoint between ■1 and ■2. It is possible to operate at an accurate focal point position to give a calculated value. In the embodiment, a configuration was explained in which an offset voltage is applied to the focus error signal to shift the focus target value. Needless to say, this can also be achieved by changing the balance using the output of the controller 14.

Also, the offset voltage V, which is the output of the controller 14, is
V2 was set to a value where the VFO amplitude level is 13 dB, but the VFO amplitude level of V2 is ■. It doesn't matter if the value of can be calculated (-1 dB.

-6dB) Needless to say.

Next, a detailed explanation of the VFO signal level detection circuit 12 will be given in the second section.
In FIG. 2, 15 is a differential circuit;
6 is a maximum point detection circuit, 17 is a maximum value detection circuit, 18 is a minimum point detection circuit, 19 is a minimum value calculation circuit, 20 is a subtracter,
21 is an accumulative adder.

VF of the optical disc recording/playback device configured as above
The operation of the block diagram of the O signal level detection circuit will be explained below.

FIG. 3(a) shows the waveform of the address signal. The control signal generation circuit 13 generates the address signal V as shown in the axis of FIG.
l'' is output in the section where FO exists.

The maximum point detection circuit 16 and the minimum point detection circuit 18 operate only when VFO is present. FIG. 3(C) shows an enlarged waveform of the VFO, and the solid line is the VFO analog signal input to the analog-digital converter 11, which is a sine wave signal with a period of 1.5T.

31-35 are digital signals sampled by the analog-digital converter 11.

Since the sampling frequency is 110.57, VFO
There are 3 points during one period. The difference circuit 15 takes the difference between the digital signals. Difference data A1 to A4 are Al=32-5L, A2=33-32°A3=S4-5
3. A4-35-84 If At > 0 and A2 < O, a maximum point exists,
"l" is output as shown in FIG. 3(d).

Also, when A3〉0 and A4〉0, a minimum point exists, and the third
1" as shown in FIG. 4(e). When the signal from the i-spark point detection circuit 16 is "B", the maximum value calculation circuit 17 calculates the value using the digital values Sl to S3 as shown in FIG. 4(f). Output like this. Since the VFO is sinusoidal, quadratic interpolation can be used in the calculation, and the maximum value yI is 8 (Sl-2·S2+33). Similarly, the minimum value calculation circuit 19 is the minimum point detection circuit 1.
When the signal of 8 is "l", it is calculated using the digital values 82 to S4 and is outputted as shown in Fig. 4 (the minimum value y2
The value of is 8 (S2-2 ・S3+S4), and the subtracter 20 subtracts y2 from yl calculated as above to obtain the VFO amplitude level 5P-F-) as shown in FIG. 4(C). '1-y2 is output. Also, if 51=4, the amplitude level 5P-P of the VFO is the difference data At,
From A2, it is calculated as (AI-A2)(A1+2・A2). Amplitude level S P-P is cumulative addition'! ￥
The values are cumulatively added at 2321 and outputted to the controller 14.

By the above operation, the VFO signal level can be detected as a stable and positive value.

Effects of the Invention As described above, the present invention has a configuration including an optical disc, a focus error signal detection circuit, an addition circuit, an address signal detection circuit, and means for detecting the amplitude level of the VFO of the address signal. The signal level of the VFO can be detected and automatically adjusted to the in-focus position, and the operation can be performed easily and stably.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an optical disc recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of a VFO signal level detection circuit of an optical disc recording and reproducing apparatus according to an embodiment of the present invention, and FIG. 3 is a block diagram of an optical disc recording and reproducing apparatus according to an embodiment of the present invention. FIG. 4 is a waveform diagram of each part of the VF○ signal level detection circuit of the optical disc recording and reproducing apparatus in the example, FIG. 4 is a characteristic diagram of the controller of the optical disc recording and reproducing apparatus according to the embodiment of the present invention, and FIG. It is a block diagram. 1... Optical disk, 2... Light beam,
3... Actuator, 4... Optical head, 5... Focus error signal detection circuit, 6
...Tracking error signal detection circuit, 7...
... Address signal detection circuit, 8 ... Addition circuit, 9 ... Focus drive circuit, 10 ...
・Trunking drive circuit, 11...Analog-
Digital converter, 12... VFO signal level detection circuit, 13... Control signal generation circuit, 14...
...controller, 15...t...differential circuit,
16...Local maximum point detection circuit, 17...Local maximum value calculation circuit, 18...Local minimum point detection circuit, 19
... Minimum value calculation circuit, 20 ... Subtractor, 21 ... Accumulation adder.

Claims (2)

[Claims] (1) An optical disc with a spiral guide groove and addresses formed by uneven pits at the beginning of sectors that divide each track, a focus error signal detection circuit, and an offset added to the output of the focus error signal detection circuit. In an optical disc recording and reproducing apparatus, the optical disk recording/reproducing apparatus is configured of an adder circuit for detecting the VFO signal level of the address signal, an address signal detecting circuit, and a means for detecting the signal level of the VFO signal of the address signal.
The means for detecting the signal level of is composed of a VFO signal level detection circuit and a controller, and the output of the controller is configured to operate to the in-focus position where the amplitude level of the VFO of the address signal is maximized when the servo is applied. By changing the focus target value, in addition to the adding circuit, the VFO signal level detection circuit calculates the VFO amplitude level of the address signal and outputs it to the controller. After the target value of focus is determined by the controller, the target value of the midpoint between the two target values is added from the controller to the adder circuit, and the operation at the in-focus position of the focus is automatically adjusted and performed. An optical disc recording/playback device characterized by: (2) a differential circuit to which the output of an analog-to-digital converter is connected; a maximum point detection circuit and a minimum point detection circuit to which the output of the differential circuit and the output of the control signal generation circuit are connected;
A local maximum point detection circuit calculates the local maximum value of VFO at an address from the output of the local maximum point detection circuit and the output of the analog-to-digital converter; VFO of
a minimum value detection circuit that calculates the minimum value of the minimum value, a subtracter that takes the difference between the output of the minimum value calculation circuit and the output of the minimum value calculation circuit and outputs the amplitude level of the VFO at the address; VFO signal level of the optical disc recording and reproducing apparatus according to item 1, which is constituted by a control signal generation circuit that generates a control signal in a section where the VFO signal of the address exists from the output and outputs it to the maximum point detection circuit and the minimum point detection circuit. The detection circuit accurately and quickly detects the VFO signal level from the address digital signal and outputs it to the controller, making it possible to automatically adjust the focus position with the servo applied. Optical disc recording/playback device.