JPH05314652A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the infringement of copyright and the spread of a pirate edition by recording data encoded by an encoding means and reading only by a decoding means corresponding to the encoding means. CONSTITUTION:Digital data is encoded by an encoder 14A before it is recorded on a magneto-optical disk 1. By the encoder 14A, the digital data outputted from a compression/expansion circuit 14, that is, music data is encoded according to a control signal outputted from a memory controller 12 while synchronizing with a system clock supplied from a system controller 17. On the other hand, the digital data read out of the disk 1 is decoded by a decoder 14b. By the decoder 14B, the data outputted from the memory controller 12 is decoded and outputted to the compression/expansion circuit 14 and decoding is executed by reverse operation of encoding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus for recording digital data such as music and voice on a recording medium such as a magneto-optical disk and reproducing the digital data read from the recording medium.

[0002]

2. Description of the Related Art In recent years, a magneto-optical disk capable of recording and reproducing while maintaining compatibility with a so-called compact disk and a reproducing apparatus thereof and a recording / reproducing apparatus thereof (so-called audio M).
D (mini disk) devices have been proposed. The diameter of this magneto-optical disk is set to 64 mm in consideration of its portability, which is smaller than the diameter of the compact disk.

In such a recording / reproducing apparatus, a disc descriptor or an index disc, which is conventionally used in a computer hard disc or the like, is used.
It was a flag-based control using a table.

FIG. 13 shows a frame structure of a conventional compact disc, and FIG. 14 shows a disc descriptor of the conventional compact disc. The subcode is called control and display and has 8 bits. The sub-code frame is assembled to form a sub-code frame. The P channel indicates the interval between songs and the middle of the song. Q channel is control
As the code, a track number, a time code, etc. are shown.

In a compact disc, the Q channel corresponds to an index table or a disc descriptor, and describes information peculiar to the disc or disc rotation as well as information that changes from moment to moment on the disc. ing. The Q channel basically has the following two pieces of information. (1). Information and flags unique to the contents of the disc (2). Information that changes from moment to moment on the disc Track number, index, time code (minutes, seconds)
etc. The information in (1) describes how the contents of the disc should be used, how they should be used, whether they can be copied or not, and the like. Various pieces of music can be accessed by combining the information in (2) alone or in combination.

That is, for protection against copyright infringement in a compact disc, read the description about "copyright" in the disc descriptor, and control the disc such as: copy permitted or not permitted generation control. By doing.

[0007]

As described above, in the conventional recording / reproducing apparatus, the disc descriptor system using the compact disc subcode is used.
It protects against copyright infringement. In such a method, the information data itself is not protected, and it is difficult to maintain high security.

Particularly, audio MD (mini disc)
When the device is used for a data storage device and a multimedia storage device, the disk descriptor or index table method has a problem that high security cannot be maintained in an advanced information system.

The present invention has been made in consideration of the above points, and an object thereof is to prevent copyright infringement, that is, to prevent the spread of so-called pirated editions.

[0010]

In a recording apparatus according to claim 1, digital data is recorded on a recording medium (for example,
It is characterized in that it is provided with an encryption means (for example, the encryption device 14A of the embodiment) for performing encryption before recording on the magneto-optical disk 1) of the embodiment.

A reproducing apparatus according to a second aspect of the present invention comprises a decoding means (for example, the decoder 14B of the embodiment) for decoding digital data read from a recording medium (for example, the magneto-optical disk 1 of the embodiment). It is characterized by

A recording / reproducing apparatus according to a third aspect of the present invention is an encryption means (for example, for encrypting digital data before recording it on a recording medium (for example, the magneto-optical disk 1 of the embodiment)).
It is characterized by comprising an encryptor 14A) of the embodiment and a decryption means for decrypting the digital data read from the recording medium (for example, the decryptor 14B of the embodiment).

According to a fourth aspect of the invention, the recording device is characterized in that the encryption means has a plurality of keys.

In the recording apparatus having the structure of the first aspect, the digital data is encrypted by the encryption means before being recorded on the recording medium. Therefore, the data recorded on this recording medium can be reproduced only by the reproducing device having the decrypting means corresponding to the encrypting means, so that the spread of pirated edition, that is, the copyright infringement can be prevented, and the high security can be maintained.

In the reproducing apparatus having the structure of the second aspect, the digital data read from the recording medium is decoded by the decoding means. Therefore, since only the data encrypted and recorded by the encryption means corresponding to the decryption means can be properly reproduced, it is possible to prevent the spread of pirated copies, that is, copyright infringement, and maintain high security.

In the recording / reproducing apparatus having the structure of the third aspect, the digital data which is encrypted by the encryption means and read from the recording medium before the digital data is recorded on the recording medium is decrypted by the decrypting means. To be done.
Therefore, since the data recorded by this recording / reproducing apparatus cannot be reproduced by another reproducing apparatus, it is possible to prevent the spread of pirated editions, that is, copyright infringement, and maintain high security.

According to another aspect of the recording apparatus of the present invention, the digital data is encrypted with a plurality of keys.
Therefore, higher security can be maintained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment in which the present invention is applied to an MD (mini disk) device. An embodiment of the present invention will be described below with reference to FIG. First, a description will be given of a case where a maximum of 74 minutes of information is recorded / reproduced on / from a magneto-optical disk having a diameter of 64 mm in the same signal format as a compact disk. In FIG. 1, the magnetic head 2 applies a magnetic field according to the modulation signal to the magneto-optical disk 1 to record the signal. The optical pickup 4 irradiates the magneto-optical disk 1 with a laser beam through the objective lens 3 to heat the magnetic recording surface to a Curie temperature or higher to erase the magnetization or read out the data recorded on the magneto-optical disk 1. To do.
The feed motor 5 causes the optical pickup 4 to move to the magneto-optical disk 1
Move in the radial direction. The spindle motor 6 rotationally drives the magneto-optical disk 1.

The head drive circuit 7 applies a modulation signal to the magnetic head 2. The servo circuit 10 outputs a rotation control signal to the feed motor 5 and the spindle motor 6 and also outputs a drive control signal for a lens actuator (not shown) of the optical pickup 4.

The encoder / decoder 11 is connected to the memory controller 12, the DRAM (dynamic RAM) 13 and the CIRC error correction section 12A via a data bus. Also, the encoder / decoder 11
It receives a control signal from the system controller 17, sends and receives a subcode signal, and sends and receives a handshake signal (asynchronous) with the memory controller 11.

When recording the digital data, that is, the music data, the encoder / decoder 11 encodes the digital data based on the known double-coded Reed-Solomon code shown in FIG. 8 and also shown in FIG. 6 (a). Known EFM (8 to 14 Modulation) modulation is performed, a subcode is added, a sync signal is added to one frame (588 channel bits) of digital data, and a known frame configuration shown in FIG. Output to the drive circuit 7.

Further, the encoder / decoder 11 detects and protects the sync signal when reproducing the digital data, that is, the music data, and the address data output from the address decoder 8 and the music data output from the RF amplifier 9 are shown in FIG. Decoding is performed based on the known double-coded Reed-Solomon code shown, and the known EFM (8 to 14 Modulation) demodulation shown in FIG. 6A is performed to demodulate the subcode and output to the data bus.

The memory controller 12 includes a data bus,
It is connected to the DRAM 13 by an address bus and a control signal line. The memory controller 12 performs control for storing digital data to be recorded or reproduced in the DRAM 13. More specifically, the memory controller 12 generates the time base, and the DRAM 1
3 for time base correction, system control for EFM modulation and demodulation and CIRC error correction, data interpolation, and DRAM 13 for data interleaving and deinterleaving.

The encryptor 14A converts the digital data, that is, the music data output from the compression / expansion circuit 14,
Encryption is performed in accordance with the control signal output from the memory controller 12 and in synchronization with the system clock supplied from the system controller 17.

FIG. 2 shows an example of the configuration of the encryptor 14A shown in FIG. The encryption key generation unit 41 generates an encryption key K1 such as a customer number. The PN code generator 51 receives the encryption key K1 and generates the PN code PN1. The electronic code book section 61 has a PN code PN1.
In response, the digital input data Ii from the compression / expansion circuit 14 is encrypted and output.

The encryption key generator 42 generates an encryption key K2 such as a family number. PN code generator 5
2 receives the encryption key K2 and generates a PN code PN2. The electronic codebook unit 62 receives the PN code PN2, further encrypts the encrypted data output from the electronic codebook unit 61, and outputs the encrypted data.

The encryption key generating section 43 generates an encryption key K2 such as a work key. PN code generator 53
Receives the encryption key K3 and generates a PN code PN3. The electronic codebook unit 63 receives the PN code PN3, further encrypts the encrypted data output from the electronic codebook unit 62, and outputs the encrypted data to the memory controller 12.

Since the encryptor shown in FIG. 2 has three encryption keys, high security can be maintained. In addition, by devising the use of the encryption key, it is possible to give variations to the use of the MD device.

The decoder 14B is used by the memory controller 12
The digital data output from, ie, is decoded and output to the compression / expansion circuit 14. Decryption is the reverse operation of encryption.

The compression / expansion circuit 14 compresses the digital data output from the A / D converter 15A and outputs the compressed digital data to the encryption device 14A and the digital data output from the decryption device 14B to the original signal. Output to the D / A converter 15B.

The filter 16A filters a stereo two-channel (for example, frequency band 5 to 20 KHZ) music signal, and the A / D converter 15A filters the filter 1.
The analog signal output from 6A is sampled at a sampling frequency of 44.1 KHZ, for example, and is supplied to the compression / expansion circuit 14 as a 16-bit digital signal. Also,
The D / A converter 15B converts the digital data output from the compression / expansion circuit 14 into an analog signal, and the filter 16B filters the analog signal output from the D / A converter 15B to perform stereo 2-channel music. Output as a reproduction signal.

The system controller 17 controls the servo circuit 10, the encoder / decoder 11, the memory controller 12, and the compression / expansion circuit 14. The system controller 12 uses the CIRC error correction unit 12A.
Receives status slag from. The display 18 receives the output signal of the system controller 17 and displays address data and the like. The operation unit 19 is for the operator to input a command or the like for causing the MD device to perform a desired operation, and the output signal of the operation unit 19 is supplied to the system controller 17.

First, the magneto-optical disk 1 shown in FIG. 3 is clamped at the recording / reproducing position by a mechanism (not shown). Disc clamping is performed by chucking a clamp plate 21 provided in the clamp area of the magneto-optical disc 1. Since the magneto-optical disk 1 is held in a case composed of an upper lid 22 and a bottom lid 23, the shutter 24 is opened at the time of recording / reproducing, and the objective lens 3 of the optical pickup 4 and the magnetic head 2 are recorded on the magneto-optical disk 1. Face to face.

When the input music signal is recorded on the magneto-optical disk 1, when a recording start key (not shown) is operated on the operation unit 19, the system controller 17 causes the servo circuit 10, the encoder / decoder 11, and the memory controller 12 to operate. , And the compression / expansion circuit 14 is set to the recording mode. The music signal passes through the filter 16A, is converted into a digital signal by the A / D converter 15A, and is input to the compression / expansion circuit 14.

The compression / expansion circuit 14 compresses to a predetermined transmission ratio and outputs it. This compression method will be described with reference to FIGS. For example, an analog signal as shown in FIG. 10 is subjected to Fourier transform of a waveform for a maximum of about 20 mmsec to sample about 1000 pieces, and the levels of each frequency of F1 to Fn are extracted from these sample values to display a spectrum as shown in FIG. It becomes like a). Here, by overlapping the distribution graphs showing the masking effect, the frequencies with a high masking effect can be found. FIG. 11B shows a spectrum display of these frequencies. That is, the data is compressed by extracting from the digital data only the data in which the minimum audible characteristic and the masking effect are taken into consideration.

By this compression, the transmission ratio (1.4 Mbit / sec) of a general compact disc is about 1/5.
Transmission ratio (0.3 Mbit / sec). The compressed digital data output from the compression / expansion circuit 14 is encrypted by the encryption device 14A and supplied to the memory controller 12.

Since the data recorded on the magneto-optical disk 1 is compressed to about 1/5, in order to record the data on the magneto-optical disk 1 in the same recording format as the compact disk, the data to be recorded is stored in the temporary memory. You need to do it. Therefore, data is temporarily stored in the DRAM 13 having a capacity of 1 Mbit based on the write control signal of the memory controller 12. Until the data is read from the DRAM 13, writing of data by the optical pickup 4 and the magnetic head 2 is prohibited by the system controller 17.

When data is read from the DRAM 13 based on the read control signal from the memory controller 12,
This data is input to the encoder / decoder 11.
The input data is C by a known CIRC encoder used for a compact disc as shown in FIG.
The data is IRC encoded, modulated according to the known EFM modulation scheme as shown in FIG. 6A, and output after forming the frame structure shown in FIG. 6B.

FIG. 9 shows the correction / correction capability by CIRC coding, and FIG. 12 shows the correction / correction probabilities by various strategies when 8-bit data occurs randomly. FIG. 7A and FIG. 7B show a low frequency spectrum and a high frequency spectrum by EFM modulation, respectively. The data thus modulated is magnetically modulated by the head drive circuit 7 in the magnetic head 2 to record the data. This recording is performed by the principle shown in FIG. 4A and the optical pickup shown in FIG. That is, the magneto-optical disk 1
In order to heat the magnetic recording surface of (1) to the Curie temperature, laser light is applied to the recording surface via the beam splitter 31 and the objective lens 3. Therefore, the magnetization of the magnetic recording surface disappears. At this time, the direction of magnetization is determined by the magnetic field modulated by the magnetic head 2,
Data is recorded.

Next, a method of reproducing the signal recorded on the magneto-optical disk 1 will be described. When a reproduction start key (not shown) is operated on the operation unit 19, the system controller 17 causes the servo circuit 10, the encoder / decoder 11, the memory controller 17, and the compression / expansion circuit 1 to operate.
Set 4 to playback mode.

As shown in FIG. 5, the optical pickup 4 irradiates the magnetic recording surface with a laser beam having a laser power lower than the laser power at the time of recording via the beam splitter 31 and the objective lens 3. The deflection angle of the laser beam reflected on the magnetic recording surface differs depending on the direction of the recorded magnetization. Therefore, the reflected beam that passes through the objective lens 3 and is reflected by the beam splitter 31 is separated by the deflection angle by irradiating the deflection beam splitter 33 through the lens 32. The separated reflected beams are applied to the light receiving elements 34 and 35, respectively. The difference between the outputs of the light receiving elements 34 and 35 is calculated by the differential amplifier 36 and output as an RF signal.

When reproducing a disc which is not a magneto-optical recordable disc but has a pit structure similar to that of a compact disc as shown in FIG. 4B, outputs of the light receiving elements 34 and 35 are reproduced. An RF signal is output by calculating the sum of the two in the adding amplifier 37. At this time, the switch 38 is switched to the output side of the summing amplifier 37.

The RF signal thus reproduced is RF
The data is input to the encoder / decoder 11 via the amplifier 9, and is also input to the address decoder 8 to extract address data, which is also input to the encoder / decoder 11. The data input to the encoder / decoder 11 is demodulated by the process reverse to the above.

Since the data recorded on the magneto-optical disk 1 is compressed to about 1/5, in order to reproduce the data on the magneto-optical disk 1 in the same reproduction format as the compact disk, the data to be reproduced is stored in the temporary memory. It is necessary to remember. Therefore, data is temporarily stored in the DRAM 13 having a capacity of 1 Mbit based on the write control signal of the memory controller 12. Until the data is read from the DRAM 13, the system controller 17 prohibits the reading of data by the optical pickup 4. When data is read from the DRAM 13 based on the read control signal from the memory controller 12, the data is decoded by the decoder 14B and then input to the compression / expansion circuit 14.

The data input to the compression / expansion circuit 14 is expanded by performing a process reverse to the above-described compression process in order to convert the data into the original transmission ratio data. further,
The decompressed data is input to the D / A converter 16,
It is output as an analog signal. By storing the data in the DRAM 13, it is possible to prevent the sound skip due to the jump of the objective lens 3 due to the vibration. That is, since the data is read from the magneto-optical disk 1 at 1.4 Mbit / sec and the data is temporarily stored in the DRAM 13, the jump of the objective lens 3 occurring during that time is generated in the DRAM 13.
Since the data from is output, skipping does not occur in hearing. In this case, since the capacity of the DRAM 13 is 1 Mbit, it is possible to cope with the jump of the objective lens 3 for about 3 seconds.

Next, a case will be described in which the data to be recorded is not compressed and is recorded with the same sound quality as the compact disc. First, when a compression-prohibited recording mode key (not shown) of the operation unit 19 is operated, the system controller 17 continuously controls the operation of the optical pickup 4 and the magnetic head 2 and the DRAM 13 by the memory controller 12.
The storage of data in the memory and the operation of the compression / expansion circuit 14 are prohibited. This makes it possible to record data with the same sound quality as a compact disc. However, the recording time is reduced to about 1/5.

Further, a case will be described in which the data to be recorded is significantly compressed by the above compression processing and then recorded. First, when a high compression recording mode key (not shown) of the operation unit 19 is operated, the system controller 17 controls the recording prohibition time of the optical pickup 4 and the magnetic head 2 to be lengthened according to the compression ratio, and the memory controller. 12
The data read-out interval from the DRAM 13 is lengthened, and the compression ratio of the compression / expansion circuit 14 is changed so as to be about 1/10 of the transmission ratio of the compact disc in consideration of the masking effect and the minimum audible limit. Let As a result, about twice the recording time can be achieved. However, the sound quality is considerably lower than that of the compact disc.

Although the number of encryption keys is 3 in the above embodiment, the present invention is not limited to this, and a number of encryption keys corresponding to the required degree of security can be used.

The encryption method is not limited to the example shown in FIG. 2, and various encryption methods can be adopted. For example, the output data of the encryptor 14A is further encrypted, and the encrypted data obtained by this is ORed with the output data of the encryptor 14A, or CBC (C
ifer Block Chainig), CFB
(Cipher Feedback), OFB (Out
Various modified examples such as a put feedback mode are possible. The bundle length at this time is, for example, CIRC.
12 symbols (bytes) of the C2 decoder of ECC, or 6 Nyquist interval length may be used.

[0049]

According to the recording apparatus of the first aspect, since the digital data is encrypted by the encryption means before being recorded on the recording medium, the data recorded on the recording medium corresponds to the encryption means. Since it can be reproduced only by the reproducing apparatus having the decoding means, it is possible to prevent the spread of pirated copies, that is, copyright infringement, and maintain high security.
In particular, the recording apparatus of the present invention is particularly effective when performing multimedia recording.

According to the reproducing apparatus of the second aspect, since the digital data read from the recording medium is decrypted by the decrypting means, only the data which is encrypted and recorded by the encrypting means corresponding to this decrypting means is recorded. Since it is not properly reproduced, it is possible to prevent the spread of pirated copies, that is, copyright infringement, and maintain high security.

According to the recording / reproducing apparatus of the third aspect, the digital data is encrypted by the encrypting means before being recorded on the recording medium, and the digital data read from the recording medium is decrypted by the decrypting means. Since the data recorded by this recording / reproducing apparatus cannot be reproduced by another reproducing apparatus, it is possible to prevent the spread of pirated editions, that is, copyright infringement, and maintain high security.

According to the recording apparatus of the fourth aspect, since the digital data is encrypted with a plurality of keys, higher security can be maintained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment in which the present invention is applied to an MD (mini disk) device.

FIG. 2 is a block diagram showing a configuration example of an encryption unit 14A of the embodiment of FIG.

FIG. 3 is a perspective view showing the configuration of an example of a magneto-optical recording disk used in the embodiment of FIG.

FIG. 4 is a principle explanatory diagram illustrating a recording / reproducing principle of the embodiment of FIG.

5 is a pickup configuration diagram showing an example of the configuration of the optical pickup of the embodiment of FIG.

FIG. 6 is a format explanatory diagram illustrating an EFM modulation method and a frame configuration of FIG. 1.

7 is a frequency characteristic diagram showing a low band spectrum and a high band spectrum based on the EFM modulation method of the embodiment of FIG.

8 is a configuration diagram showing a configuration of a CIRC encoder / decoder according to the exemplary embodiment of FIG. 1. FIG.

9 is a capability explanatory diagram showing correction / correction capability by the CIRC encoder of the embodiment of FIG. 1. FIG.

10 is an explanatory diagram for explaining a compression method of the embodiment of FIG.

11 is an explanatory diagram for explaining the compression method of FIG. 1. FIG.

FIG. 12 is an explanatory diagram for explaining correction / correction probabilities according to various strategies when 8-bit data randomly occurs in the embodiment of FIG. 1;

FIG. 13 is an explanatory diagram showing a frame structure of a conventional compact disc.

FIG. 14 is an explanatory view showing a disc descriptor of a conventional compact disc.

[Explanation of symbols]

 1 magneto-optical disk 2 magnetic head 4 optical pickup 7 head drive circuit 8 address decoder 9 RF amplifier 10 servo circuit 12 memory controller 13 DRAM 14 compression / expansion circuit 14A encryption device 14B decryption device 15A A / D converter 15B D / A converter 17 System controller

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[Procedure amendment]

[Submission date] June 5, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to music, voice, video and
The present invention relates to a recording / reproducing apparatus for recording digital data such as computer data on a recording medium such as a magneto-optical disk and reproducing the digital data read from the recording medium.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art In recent years, a magneto-optical disk capable of recording and reproducing and a recording and reproducing apparatus therefor (so-called audio MD (mini disk) apparatus) have been proposed. The diameter of this magneto-optical disk is set to 64 mm in consideration of its portability, which is smaller than the diameter of the compact disk.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

As described above, in the conventional recording / reproducing apparatus, the disc descriptor system using the compact disc subcode is used.
It protects against copyright infringement. Such methods, information de - data itself is not protected, to maintain a high security is difficult.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

The memory controller 12 uses a data bus, an address bus, and a control signal line to control the RAM 13
It is connected to the. The memory controller 12 performs control for storing digital data to be recorded or reproduced in the RAM 13. More specifically, the memory controller 12 generates the time base, and the RAM 13
To perform time base correction, to perform system control for EFM modulation and demodulation and CIRC error correction, to perform data interpolation, and to use RAM 13 to perform data interleaving and deinterleaving.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

The system controller 17 controls the servo circuit 10, the encoder / decoder 11, the memory controller 12, and the compression / expansion circuit 14. The system controller 12 uses the CIRC error correction unit 12
The signal that controls A controls and receives status slag. The display 18 receives the output signal of the system controller 17 and displays address data and the like. The operation unit 19 is for the operator to input a command or the like for causing the MD device to perform a desired operation, and the output signal of the operation unit 19 is supplied to the system controller 17.

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Since the data recorded on the magneto-optical disc 1 is compressed to about 1/5, the data to be recorded is stored in the temporary memory in order to record on the magneto-optical disc 1 in the same recording format as the compact disc. You need to do it. Therefore, based on the write control signal of the memory controller 12, the data is temporarily stored in the RAM 13 having a capacity of 1 Mbit. Until the data is read from the RAM 13, writing of data by the optical pickup 4 and the magnetic head 2 is prohibited by the system controller 17.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

When data is read from the RAM 13 based on the read control signal from the memory controller 12,
This data is input to the encoder / decoder 11.
The input data is C by a known CIRC encoder used for a compact disc as shown in FIG.
The data is IRC encoded, modulated according to the known EFM modulation scheme as shown in FIG. 6A, and output after forming the frame structure shown in FIG. 6B.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

Next, a method of reproducing the signal recorded on the magneto-optical disk 1 will be described. When a reproduction start key (not shown) is operated in the operation unit 19, the system controller 17 sets the servo circuit 10, the encoder / decoder 11, the memory controller 12 and the compression / expansion circuit 14 in the reproduction mode.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

Since the data recorded on the magneto-optical disk 1 is compressed to about 1/5, the magneto-optical disk 1
In order to reproduce in the same reproduction format as the compact disc, it is necessary to store the data to be reproduced in the temporary memory. Therefore, based on the write control signal of the memory controller 12, the data is temporarily stored in the RAM 13 having a capacity of 1 Mbit. Until the data is read from the RAM 13, the data read by the optical pickup 4 is
It is prohibited by the system controller 17. R based on the read control signal from the memory controller 12
When the data is read from the AM 13, the data is decoded by the decoder 14B, and then the compression / expansion circuit 14 is executed.
Entered in.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

The data input to the compression / expansion circuit 14 is expanded by performing processing reverse to the above-described compression processing in order to convert the data to the original transmission ratio data. further,
The decompressed data is input to the D / A converter 16,
It is output as an analog signal. By storing the data in the RAM 13, it is possible to prevent the sound skip due to the jump of the objective lens 3 due to the vibration. That is, data is read from the magneto-optical disk 1 at 1.4 Mbit / sec,
Since the data is temporarily stored in the RAM 13, the jump of the objective lens 3 which occurs during that time is output from the RAM 13 and therefore no sound skip occurs in the sense of hearing. In this case, since the capacity of the RAM 13 is 1 Mbit, it is possible to cope with the jump of the objective lens 3 for about 3 seconds.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

Next, without compressing the data to be recorded,
The case of recording with the same sound quality as a compact disc will be described. First, when a compression-prohibited recording mode key (not shown) of the operation unit 19 is operated, the system controller 17
Controls the optical pickup 4 and the magnetic head 2 continuously, and the RAM 13 by the memory controller 12
The storage of data in the memory and the operation of the compression / expansion circuit 14 are prohibited. This makes it possible to record data with the same sound quality as a compact disc. However, the recording time is reduced to about 1/5.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction content]

Further, a case will be described in which the data to be recorded is significantly compressed by the compression processing described above and is recorded.
First, when a high compression recording mode key (not shown) of the operation unit 19 is operated, the system controller 17 controls the recording prohibition time of the optical pickup 4 and the magnetic head 2 to be lengthened according to the compression ratio, and the memory controller. 1
The interval of reading data from the RAM 13 by 2 is lengthened, and the compression ratio of the compression / expansion circuit 14 is set to about 1/10 of the transmission ratio of the compact disc in consideration of the masking effect and the minimum audible limit. Change. As a result, about twice the recording time can be achieved. However, the sound quality is considerably lower than that of the compact disc.

[Procedure Amendment 13]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (4)

[Claims] 1. A recording device for recording digital data on a recording medium, comprising: an encryption means for encrypting the digital data before recording it on the recording medium. 2. A reproducing apparatus for reproducing digital data recorded on a recording medium, comprising a decoding means for decoding digital data read from the recording medium. 3. Digital data is recorded on a recording medium,
In a recording / reproducing apparatus for reproducing digital data recorded on the recording medium, encryption means for encrypting the digital data before recording the digital data on the recording medium, and decoding the digital data read from the recording medium A recording / reproducing apparatus comprising: a decoding unit. 4. The recording apparatus according to claim 1, wherein the encryption unit has a plurality of keys.