KR19980059934A - Heterogeneous optical disk rotary servo device - Google Patents

Abstract

The present invention relates to a device for sharing some circuits for recording and reproducing heterogeneous optical discs having different disc thicknesses and recording densities. In particular, in a rotary servo device of heterogeneous optical discs having different recording densities and thicknesses, data read from the disc is counted. A synchronization signal detector for detecting a synchronization signal corresponding to the format of the heterogeneous optical disk, and counting the output of the synchronization signal generator to predict the position where the next synchronization signal is generated to generate a prediction synchronization signal corresponding to the format of the heterogeneous optical disk. The hardware of the rotating servo is realized by using a predictive synchronization signal generator and a window signal generator which counts the output of the synchronization signal detector and generates a window signal having a predetermined pulse width at the position where the synchronization signal is to be generated. Reduced volume reduces gate count in IC development and saves money Can.

Description

Heterogeneous optical disk rotary servo device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for sharing some devices in a disc player for recording and playing heterogeneous optical discs having different disc thicknesses and recording densities, and more particularly, to a servo controlling rotation of heterogeneous optical discs having different disc thicknesses and recording densities. The present invention relates to a heterogeneous optical disc combined rotation servo device for sharing a synchronization signal detection circuit.

In recent years, optical discs are called Digital Video Discs having a larger recording capacity than conventional compact discs (hereinafter referred to as CDs) due to continuous development efforts to increase recording capacity. ) Was developed.

A DVD has a higher recording density than a CD and a shorter distance from the surface of the disc to the information recording surface. In fact, a DVD has a distance of 0.6 mm from the surface of the disc to the information recording surface, while a CD has 1.2 mm.

CD has a track pitch of 1.6 µm, a pit length of 0.834 µm, a light source wavelength of 780 nm, and an objective lens with a numerical aperture of 0.45, whereas a DVD has a track pitch of 0.74 µm, a pit length of 0.4 µm, and a light source wavelength of 650 nm. The numerical aperture of the objective lens is 0.60.

That is, the recording capacity of a DVD is 6 to 8 times that of a CD, and video and audio data compression is used, and one film of the same quality as that of the current TV broadcast is recorded on a disc having a diameter of 120 nm.

At this time, the data may be recorded on both sides of the disk, or the recording surface may be formed in two layers to increase the recording capacity.

In addition, considering that a large amount of software in a CD format is used, a DVD needs to be able to play a CD. In other words, higher regeneration compatibility must be ensured.

At this time, since the DVD format has been released since the commercialization of the CD format, the formats of the CD and DVD are slightly different in each part.

Therefore, in the related art, as shown in FIG. 1, the rotation servo is separately configured for each format to control disk rotation.

At this time, the rotation servo that controls the disk motor for rotating the disk includes a synchronization signal read from the disk to drive the disk at a constant linear velocity (CLV), address information of a trace position, and a clock signal as a reference for a control operation. And it contains various information such as command from microcomputer, and the physical data format inputted to each rotary servo is NRZI type, but the synchronization signal pattern and frame length are different.

Accordingly, the CD rotation servo 11 and the DVD rotation servo 12 are configured independently, and the CD rotation servo 11 and the DVD rotation servo 12 are respectively reproduced according to the type of disc to be reproduced, for example, CD or DVD. The output of the rotary servo 11 or the output of the DVD rotary servo 12 was selected to connect a multiplexer 13 for controlling the rotation of the disk motor to configure a CD / DVD combined servo.

At this time, when the CD or DVD is played back, the disc motor starts to rotate at a certain speed, and the optical pickup reads out the information recorded on the disc.

EFM (Eight to Fourteen Modulation) modulation for converting 8-bit data into 14-bit is performed on the read information, and the EFM-modulated data is non-return-to zero, inverted (NRZI) and simultaneously The CD rotating servo 11 and the DVD rotating servo 12 are input.

The NRZI modulation is a modulation rule for inverting data in a signal of '1'. In other words, if '1' is met, the current state is reversed.

Therefore, the CD rotary servo 11 outputs a disc motor control signal conforming to the CD format, and the DVD rotary servo 12 outputs a disc motor control signal conforming to the DVD format.

At this time, if the disc type to be reproduced is CD, the output of the CD rotation servo 11 is output through the multiplexer 13, and if the DVD is output, the output of the DVD rotation servo 12 is output through the multiplexer 13.

As described above, in order to secure the upper compatibility of the DVD player, a CD rotating servo and a DVD rotating servo are respectively constructed and selectively used.

Therefore, there is a problem that the amount of rotation servo and hardware for controlling the rotation of the CD or DVD is increased, the configuration is complicated, and the cost is increased.

The present invention has been made to solve the above problems, and an object of the present invention is to develop an integrated circuit (IC) by reducing the amount of hardware of the rotary servo by using a common part of the synchronization signal generation used for phase comparison in the rotary servo. The purpose of the present invention is to provide a heterogeneous optical disk rotating servo device which reduces the number of gates and reduces costs.

In order to achieve the above object, a characteristic of a dual optical disc rotating servo device according to the present invention includes a synchronization signal detection unit for counting data read from a disc and detecting a synchronization signal corresponding to a format of a heterogeneous optical disc; A prediction synchronization signal generator for counting the output of the synchronization signal generator to predict the position at which the next synchronization signal is generated, and generating a prediction synchronization signal corresponding to the format of the heterogeneous optical disc; It is configured to include a window signal generator for generating a window signal having a predetermined pulse width at the position to be generated.

1 is a block diagram of a conventional rotary servo device for a heterogeneous optical disc

Figure 2 is a block diagram of the configuration of a dual-purpose optical disc rotating servo device

3A to 3E are timing diagrams illustrating the operation of each part of FIG. 2 using CD as an example.

Explanation of symbols for the main parts of the drawings

20: synchronization signal detector 21, 31: counter

22: CD sync signal detector 23: DVD sync signal detector

24, 34, 43: multiplexer 30: prediction synchronization signal generator

32: CD predictive synchronization signal generator 33: DVD predictive synchronization signal generator

40: window signal generator

41: CD window signal generator 42: DVD window signal generator

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 2 is a block diagram showing the configuration of a rotary servo device for a heterogeneous optical disc according to the present invention, and in particular, a detailed block diagram of a synchronization generating circuit.

Referring to FIG. 2, a synchronization signal detection unit 20 for detecting a synchronization signal used for phase comparison from an NRZI modulated signal and a synchronization signal detection unit 20 in preparation for a case where a synchronization signal is not detected due to an error, are shown in FIG. A prediction synchronization signal generator 30 for predicting a position to be generated and generating a prediction synchronization signal, and a window for generating a window signal at a location where a synchronization signal will be generated to reduce a synchronization signal detection error in the synchronization signal detector 20. It is configured to include a signal generator 40.

The synchronization signal detection unit 20 includes a counter 21 for counting NRZI modulated signals, and a CD synchronization signal detection unit 22 and counter 21 for detecting a synchronization signal conforming to the CD format using the output of the counter 21. Selects and outputs the sync signal detected by the CD sync signal detector 22 or the DVD sync signal detector 23 according to the type of disc, according to the disc type It consists of a multiplexer 24.

The prediction synchronization signal generator 30 uses a counter 31 for counting the output signal of the synchronization signal detector 20 and a CD prediction synchronization for generating a prediction synchronization signal for a CD format using the output of the counter 31. The DVD predictive synchronization signal generator 33 for generating a predictive synchronization signal suitable for the DVD format by using the signal generator 32, the output of the counter 31, and the CD predictive synchronization signal generator 32 according to the disc type. Or a multiplexer 34 for selectively outputting the predictive synchronization signal generated by the DVD predictive synchronization signal generator 33.

The window signal generator 40 uses the output of the counter 31 to match the DVD format by using the output of the CD window signal generator 41 and the counter 31 that generate a window signal conforming to the CD format. The DVD window signal generator 42 for generating a window signal, and the multiplexer 43 for selectively outputting the window signal generated by the CD window signal generator 41 or the DVD window signal generator 42 according to the disc type. It consists of.

In the present invention configured as described above, the counter 21 of the sync signal detector 20 counts the NRZI modulated signals and outputs them to the CD sync signal detector 22 and the DVD sync signal detector 23.

At this time, if the length of the pit counted as shown in FIG. 3A is 11T and the pit and pit interval is 11T, the CD sync signal generator 22 determines that the CD is a sync signal and generates a pulse as shown in FIG. 3B. Output to the multiplexer 24.

Here, T is the length of one clock pulse and 11T is the length of 11 clock pulses.

In addition, if the length of the counted pit is 14T, the DVD synchronization generating unit 23 determines that the DVD is a synchronization signal, and generates a pulse at the position to output the pulse to the multiplexer 24.

At this time, the pulse generated by the CD synchronization signal detector 22 or the pulse generated by the DVD synchronization signal detector 23 becomes a detection synchronization signal.

The multiplexer 24 selects the output of the CD sync signal detector 22 when the type of the disc to be played is CD, and selects the output of the DVD sync signal detector 23 when the DVD is played and outputs the final sync signal. The counter 31 outputs to the counter 31 of the synchronization signal generator 30.

The counter 31 of the prediction synchronization signal generator 30 is in a disabled state and starts counting when a detection synchronization signal is input.

The CD prediction synchronizing signal generator 32 generates a CD prediction synchronizing signal as shown in FIG. 3D when the output of the count 31 becomes a section between the CD detection synchronizing signal and the next CD detection synchronizing signal, and generates the DVD prediction synchronizing signal. The unit 33 generates a DVD predictive synchronization signal and outputs it to the multiplexer 34 when the output of the counter 31 becomes a section between the DVD detection synchronization signal and the next DVD detection synchronization signal.

The multiplexer 34 selects the output of the CD predictive synchronization signal generator 32 when the type of the disc to be reproduced is CD, and selects the output of the DVD predictive synchronization signal generator 33 when the DVD is a final predicted synchronization signal. Output

Here, the reason for generating the prediction synchronization signal is, for example, when the CD synchronization signal should be detected at the g position of FIG. 3A, but in order to prepare for this since there is no synchronization signal to compare with the reference synchronization when the phase is not detected by an error. The prediction synchronization signal is used for the comparison.

On the other hand, when the output of the counter 31 becomes a section between the CD detection synchronization signal and the next CD detection synchronization signal, the CD window signal generator 41 uses a predetermined window before and after the detection synchronization signal as a CD window signal in FIG. 3C. When the output of the counter 31 becomes a section between the DVD detection synchronization signal and the next DVD detection synchronization signal, the DVD window signal generator 33 generates a predetermined period before and after the detection synchronization signal as a DVD window signal. Output to the multiplexer 34.

The multiplexer 43 selects the output of the CD window signal generator 41 when the type of the disc to be reproduced is CD, and outputs the final window signal by selecting the output of the DVD window signal generator 42 when the DVD is a DVD.

Here, the window signal is regarded as having been matched once to the error of a predetermined bit among the detection synchronization patterns, and the synchronization signal detected in the window generation section is generated to recognize the detection synchronization signal.

In order to reduce the synchronization detection error by acknowledging a synchronization signal that is somewhat out of a generated position as a detection synchronization signal, the window signal pulse width may vary depending on the designer.

For example, as shown in position f of FIG. 3B, the synchronization signal out of the window section is not recognized as the detection synchronization signal, and as in position h of FIG. 3B, the synchronization signal within the window section is recognized as the detection synchronization signal.

If there is no synchronization signal coming into the window as in the i position of FIG. 3b, the prediction synchronization signal of FIG. 3d is replaced.

When the synchronous signal is detected as described above, the phase of the synchronous signal and the reference synchronous signal of FIG. 3E are compared and the rotation of the disk motor is controlled using the phase difference.

That is, the rotation speed of the disk motor is increased or decreased according to the phase difference until the phase difference between the reference synchronization and the detection synchronization is identical.

Since the CDs and DVDs share the large gate counts 21 and 31, and only the frame length and the length of the sync signal pattern are different, only the values of the remaining blocks except the counters 21 and 31 are set for the CD or DVD. By doing so, it is possible to add a CD rotating servo to a DVD rotating servo with only minimal circuit addition.

The present invention can be designed such that the rest of the circuits other than the synchronous signal detection circuit can share a part of the circuit with the CD and the DVD.

As described above, according to the rotary servo device for heterogeneous optical discs according to the present invention, the CD and the DVD share a circuit which generates a synchronization signal, a prediction synchronization signal, and a window signal in consideration of the phase error. By reducing the amount of hardware in the rotary servo, the number of gates in IC development can be reduced, and the cost can be reduced.

Claims (4)

A rotational servo apparatus for heterogeneous optical discs having different recording densities and thicknesses, comprising: a synchronization signal detector for counting data read from the disc and detecting a synchronization signal corresponding to the format of the heterogeneous optical disc; A prediction synchronization signal generator for counting the output of the synchronization signal generator to predict a position at which a next synchronization signal is generated to generate a prediction synchronization signal corresponding to a format of a heterogeneous optical disk; Heterogeneous optical, characterized in that the window signal generation unit for generating a window signal having a predetermined pulse width at the position where the synchronization signal will be generated by counting the output of the synchronization signal detection unit commonly used when reproducing heterogeneous optical discs having different recording densities and thicknesses. Combined rotary servo device. 2. The apparatus of claim 1, wherein the sync signal detector comprises: a counter for counting pulse signals of data read from the disk, a CD sync signal detector for detecting a sync signal conforming to a CD format using the output of the counter, Heterogeneous, comprising: a DVD sync signal detector for detecting a sync signal in accordance with a DVD format by using an output; and a multiplexer for selectively outputting a sync signal detected by the CD sync signal detector or a DVD sync signal detector according to a disc type Rotating servo device for optical disc. The apparatus of claim 1, wherein the prediction synchronization signal generator comprises: a counter for counting an output signal of the synchronization signal detector; a CD prediction synchronization signal generator for generating a prediction synchronization signal suitable for a CD format by using the output of the counter; A DVD predictive sync signal generator for generating a predictive sync signal suitable for a DVD format by using the output of the counter, and a predictive sync signal generated by the CD predictive sync signal generator or a DVD predictive sync signal generator according to a disc type. Rotating servo device for use with heterogeneous optical disks, characterized in that it consists of a multiplexer for selective output. The method of claim 1, wherein the window signal generation unit comprises: a counter for counting an output signal of the synchronization signal detection unit, a CD window signal generation unit for generating a window signal conforming to a CD format using the output of the counter, A DVD window signal generator for generating a window signal conforming to the DVD format by using an output and a multiplexer for selectively outputting the window signal generated by the CD window signal generator or the DVD window signal generator according to the disc type. Heterogeneous optical disk combined rotation servo device characterized in that.