JP3045061B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to digital video high quality long-time recording / reproducing an apparatus on the optical disk, in particular, to improve the access speed or the like by concurrently accessing both sides of the optical disk of the front and back the same format Record /
The present invention relates to an optical disk device for reproducing.

[0002]

2. Description of the Related Art In an optical disc having a recording surface on both sides and a recording track formed in a spiral shape, to simultaneously record or reproduce data on the both sides in the same direction from the inner circumference to the outer circumference, it is necessary to use both sides. What is necessary is just to reverse the direction of a spiral. However, two types of masters are required to make a spiral-format inverted-format disk, and the process up to lamination must be managed separately for the two types, resulting in high costs.

[0003] Therefore, when using a spiral disk with the same orientation on the front and back and recording or reproducing simultaneously from the inner circumference to the outer circumference on one side and from the outer circumference to the inner circumference on the other side, the spirals with the same orientation on the front and back are used. From the opposite direction, and recording or reproduction of an optical disc having a recording surface of the same format on the front and back sides can be performed. At this time, the preformat portion of each sector is reproduced in the reverse direction on the other recording surface (this is referred to as the back surface), so that a method for reading address information in the reverse direction is required.

As shown in FIG. 6, as one of the devices, a signal memory reproduced in the backward direction is temporarily stored using a waveform memory (wave memory) 13 and time-reversed to reproduce a signal waveform in the forward direction. Japanese Patent Application Laid-Open No. 5-2 / 1993 discloses an example in which address information on the back side is obtained by converting the
90380.

A reproduction signal of a preformat portion of a predetermined sector reproduced in the reverse direction is A / D converted and temporarily stored in the waveform memory (wave memory) 13. When a sector mark of the predetermined sector is detected. The waveform data stored in the waveform memory (wave memory) 13 is time-inverted and read, and the read data is D / A converted to a forward reproduction signal. This forward reproduction signal is demodulated by the sector address demodulation circuit 14 to obtain forward address information.

As shown in FIG. 7, in this conventional apparatus, the front side (side A) is recorded / recorded in the same direction as the preformat direction.
Since the data is reproduced, for example, after reading the address information of the preformat portion of the sector A, the data is recorded in the data portion of the sector A.

As shown in FIG. 7, recording / reproduction is performed on the back surface (surface B) in the direction opposite to the preformat direction. For example, after reading the address information of the preformat portion of sector B, the sector ( Data is recorded in the data section of B-1).

[0008]

The problems in the above-mentioned conventional example are as follows. (1) The A / D conversion sampling rate of the waveform memory (wave memory) needs to be approximately three times the maximum frequency of the prepit, and is generally approximately 20 MHz. If the D / A conversion is performed at the same rate, the required time is the same as the reproduction time of the preformat section, and the data enters the data area before the address information is read, so that the recordable capacity is reduced by about 5%.

For example, a sector to be read, recorded or reproduced, after the reverse reproduction signal of the preformat portion of the sector B is time-reversed by a waveform memory (wave memory) to be a forward reproduction signal, and its address information is read. Then, recording / reproduction is performed on the data portion of the sector (B-1). At this time, since it takes time to invert and reproduce the signal in the waveform memory (wave memory), the signal enters the data area (data section) before the address information is read, and the recordable capacity is reduced.

In the conventional example, assuming that the maximum frequency is 7.2 MHz, the writing / reading speed is approximately three times that of 20 MHz.
z. The address reading time is about the same as the reproduction time (37.5 μs) of the preformat section.

(2) To avoid the above problem, D
The waveform may be read at a high / A conversion rate. However, the pre-pit reproducing circuit also needs to be compatible with high speed, which causes a high cost including the D / A converter.

[0012]

Means for Solving the Problem Normally, a modulation signal called bi-phase modulation or PE (Phase Encoding) that always includes clock information for each bit cell is included in a modulation signal of a preformat section in which address information is previously formed in pits. Used. This type of modulated signal can be demodulated in the reverse direction even if it is reproduced in the direction opposite to the recording order.

Therefore, the preformat section is demodulated in the reverse direction, the reverse data after demodulation is temporarily stored, and the address information is obtained by means of time-reversing and reading. By using a data memory to which a demodulated signal is supplied instead of using a waveform memory (wave memory) as in a conventional optical disk device, and supplying the demodulated signal to the data memory, writing/
Even if the reading speed is low, demodulation can be performed at high speed.

Focusing on the above points, the invention of claim 1 is:
Digital moving pictures are recorded on both sides of a rewritable double-sided optical disk having the same format on both sides, in which address information modulated by a modulation signal containing clock information for each bit cell is formed by pre-pits, and recording tracks are formed in a spiral or concentric manner. An optical disc apparatus for reproducing the same, comprising recording / reproducing means 1A and 1B for recording / reproducing digital moving images on both sides of the optical disc,
The sector mark detecting means 41A and the sector address demodulating means 42A record or reproduce data in the forward direction with respect to the format, and the other surface includes the reverse sector mark detecting means 41B, the reverse sector address demodulating means 42B and the stack memory. The sector address portion formed by the pre-pits is reproduced in the reverse direction by the data memory 5 for one address information data , which operates as one , and is demodulated by the sector address demodulation means 42B in the reverse direction. The signal is temporarily stored in the data memory 5, and after detecting the sector mark in the reverse direction, the signal is inverted in time and read to obtain the forward address information, and the digital moving image is recorded and reproduced. .

According to a second aspect of the present invention, in the optical disk device of the first aspect, the data memory 5 includes a counter 51.
And a random access memory (RAM) 52. The data memory 5 is supplied with a demodulated signal (demodulated signal).

According to a third aspect of the present invention, in the optical disk device of the first aspect, the sector address demodulating means 42
A and 42B are composed of a peak detection circuit 6, a flip-flop circuit 7, and a demodulation circuit 8.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the optical disk apparatus of the present invention will be described below with reference to the drawings. As shown in FIG. 1, optical heads 1A and 1B and a recording / reproducing circuit are arranged on both sides of an optical disc having recording surfaces of the same format on the front and back sides and having recording tracks formed in a spiral shape. On one corresponding recording surface (surface), the optical head 1B on the opposite side to the format in the forward direction
Is recorded or reproduced in the opposite direction to the format on the other recording surface (hereinafter referred to as the back surface) corresponding to.

As shown in FIG. 1, on the surface of the optical disk, the preformat portion is reproduced in the forward direction by the optical head 1A, and is sequentially reproduced by the sector mark detecting means 41A and the sector address demodulating means 42A constituting the demodulating means 2A. The direction address information is obtained. Since the surface (side A) is recorded / reproduced in the same direction as the preformat direction, for example, after reading the address information of the preformat part of sector A, data is recorded in the data part of sector A.

On the other hand, the optical head 1
Since the preformat portion is reproduced in the reverse direction by B, the forward address information is obtained by the sector address reverse reading circuit 3. On the back side (B side), recording / reproduction is performed in the direction opposite to the preformat direction.
After reading the address information of the preformat portion of sector B, data is recorded in the data portion of sector (B-1).

The above-mentioned sector address reverse reading means 3
Is composed of a demodulating means 2B and a data memory 5, and the signal of the preformat section reproduced in the reverse direction is demodulated by the demodulating means 2B in the reverse direction. The signal demodulated by the demodulation circuit 2B is supplied to the data memory 5 where it is temporarily stored, converted to forward data with time inversion, and outputs forward address information.

Next, one embodiment of the sector address reverse reading circuit 3 shown in FIG. 1 will be described below with reference to FIG. Each sector is read later in the order of the buffer, the data section, and the address section by the optical head 1B which proceeds in the reverse direction to the format of the optical disc, contrary to the normal reproduction order.

These signals are demodulated in real time by the sector address demodulation means 42B in the reverse direction, and are stored in real time in the stack memory (memory for performing last-in first-out operation) 5 as data memory in the reverse direction. You.

The data memory 5 includes an up / down counter 51 and random access memories (RAM, Random).
Access Memory) 52, and has a capacity to store address data for one sector of the preformat section.

Since the data memory 5 just needs to store the supplied demodulated data, the data capacity is about 20 bytes for one sector of address information, and the data capacity is
Since a small memory is sufficient, it is also advantageous in terms of cost, and the writing speed is only half of the prepit maximum frequency.
MHz.

In backward reading, a sector mark is reproduced immediately after an address portion. Therefore, the sector mark in the opposite direction is used as the sector mark detecting means 41B constituting the demodulating means 2B.
, The data of the address portion for one sector is stored in the stack memory 5, and if this is inverted and read out, the address information in the forward direction can be obtained.

The speed at which address data is read from the stack memory 5 with time inversion can be sufficiently higher than the writing speed. For example, when reading is performed at 20 MHz, the time required for reproducing the preformat portion is approximately 7 hours.
Since only one-half is required, the address information can be sufficiently read in the buffer area. Therefore, there is no possibility that the recording capacity is reduced by entering the data area.

In the present invention, assuming that the maximum frequency is 7.2 MHz, the writing speed may be approximately half of 3 to 4 MHz.
The reading speed can be made higher than the writing speed. For example, if the frequency is set to approximately 20 MHz, which is the same as the conventional example, it becomes approximately 1/7 (approximately 5 to 6 μs) of the reproduction time of the preformat section.

An embodiment of an apparatus for demodulating address information formed by pits modulated by a PE (Phase Encoding) signal will now be described with reference to the drawings. FIG. 3 is a block diagram of a demodulation device for a PE modulation signal, and FIGS. 4 and 5 are signal waveform diagrams of a demodulation device for a PE modulation signal.

First, in the case of forward reproduction, as shown in FIG. 4, a peak of a reproduction signal waveform a of a pit reproduced by the optical head 1A is detected by a peak detection circuit 6, thereby obtaining pit position information b. Get.

Next, the output of the peak detection circuit 6 is supplied to a T-type flip-flop circuit 7 to obtain a PE modulation signal c having the pit position information b as a transition point. Next, the data is converted by the demodulation circuit 8 into NRZ data d of address information by a clock not shown. The PE modulation is a modulation method in which polarity is inverted when data is "1" and downward when data is "0". A signal reproduced in the forward direction is directly forward
It is converted to an E signal.

In the case of reverse reproduction, as shown in FIG. 5, a reproduction signal waveform a of a pit reproduced by the optical head 1B is used.
Is detected by the peak detection circuit 6 to obtain pit position information b.

Next, the output of the peak detection circuit 6 is supplied to a T-type flip-flop circuit 7 to obtain a PE modulation signal c having the pit position information b as a transition point. Next, the signal is converted into NRZ data d of address information by a demodulation circuit 8 by a clock (not shown) and stored in the stack memory 5.

The PE modulation is a modulation method in which the polarity is inverted when the data is "1" and downward when the data is "0". The signal reproduced in the reverse direction as shown in FIG. Is converted to a PE signal. Therefore, demodulation in reverse reproduction is possible, and sector marks are easily detected.

In the present invention, the reverse reproduction signal is demodulated in the reverse direction, the demodulated signal (demodulated data) is taken into the data memory 5, and inverted and output. Since the capacity of the data memory is sufficient for one address information data, the time until the forward address data is read is short, and the data memory does not go into the data area (data portion).

[0035]

According to the present invention, there is provided an apparatus for recording / reproducing data on a rewritable double-sided optical disk having the same format on the front and back sides. Means for obtaining address information by writing / time-reversing reading to / from a memory, demodulating a reproduced signal read from a disk in the reverse direction, and writing a demodulated signal (a signal after demodulation) to a data memory; Since the read / write operation is performed in reverse, recording / reproduction in the direction opposite to the format can be performed at high speed, and high-quality digital moving images can be simultaneously recorded / reproduced on the optical disk of the same format on both sides. Was.

Further, since the capacity of the data memory is about 20 bytes for one address information data , the time required for reading the forward address data is short, and the data memory does not go into the data area (data section). Also, data memo
The size of the data can be as large as one address information data.
And the memory can be configured at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an optical disk apparatus according to the present invention.

FIG. 2 is an embodiment of an address reverse reading circuit.

FIG. 3 is a block diagram of a demodulation device for a PE modulation signal.

FIG. 4 is a signal waveform diagram of a PE modulation signal demodulation device.

FIG. 5 is a signal waveform diagram of a PE modulation signal demodulation device.

FIG. 6 is a block diagram illustrating an example of a conventional optical disk device.

FIG. 7 shows an example of a format of an optical disk device.

[Explanation of symbols]

1A, 1B Optical head 2A, 2B Demodulation means 3 Sector address reverse reading means 5 Data memory, stack memory 6 Peak detection circuit 7 T-type flip-flop circuit 8 Demodulation circuit 41A, 41B Sector mark detection means 42A, 42B Sector address demodulation means 51 Counter (Up / Down Counter) 52 Random Access Memory (RAM, Random Acc)
ess Memory)

Claims (3)

(57) [Claims] A digital moving picture is recorded on a rewritable double-sided optical disc having the same format on both sides, in which address information modulated by a modulation signal including clock information for each bit cell is formed in prepits and recording tracks are formed in a spiral or concentric manner. record the, in the optical disc apparatus for reproducing this, a recording / reproducing means for recording / reproducing digital video on the optical disk both surfaces, one surface, the sector mark detecting means and the sector address demodulating means, with respect to format The other surface is formed by the pre-pits by a reverse sector mark detecting means, a reverse sector address demodulating means and a data memory for one address information data which operates as a stack memory. Play back the sector address part The sector address demodulating means demodulates the signal, temporarily stores the demodulated signal in the data memory, detects the reverse sector mark, reverses the time, reads it out, obtains the forward address information, and records or records the digital moving image. An optical disk device characterized by being configured to reproduce. 2. The optical disk device according to claim 1, wherein said data memory comprises a counter and a random access memory, and a demodulated signal is supplied to said data memory. . 3. The optical disk device according to claim 1, wherein said sector address demodulating means comprises a peak detecting circuit, a flip-flop circuit, and a demodulating circuit.