JPH11259974A - Information storage medium for deteriorated signal digital information and method and device for processing deteriorated signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate information selection of a user in a ciphered state by restoring digital information divided in the time base direction to space axial direction, rearranged in the time base direction to space axial direction in block and signal deteriorated based on the information detected with a signal deteriorative information detection part. SOLUTION: An information reproducing part 42 reproduces a signal on a record medium such as an optical disk etc., by an optical pickup means, and inputs the reproduced signal to a signal restoration part 44 and the signal deteriorative information detection part 43. The signal deteriorative information detection part 43 generates a random signal by using key information, and recognizes signal deteriorative information based on this. When the signal deteriorative information detection part 43 forms the signal for restoring the signal based on this signal deteriorative information to supply it to the signal restoration part 44, block shuffling is released, and a polarity inversion part of a discrete cosine transform coefficient is restored. The restored signal is inputted to a decoder part 45, and PCM, MPEG, AC-3 etc., are decoded. The decoded signal is supplied to a speaker or an earphone 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage medium for signal-deteriorated digital information and a signal-deterioration processing method and apparatus. For digital information that handles still images and stereoscopic images distributed in the direction, or video (video) information that is continuous in the time axis direction along with the two-dimensional spatial distribution, illegal copying of such digital information This is an improvement of copy protection technology to prevent or prevent unauthorized use of such digital information.

[0002]

2. Description of the Related Art A conventional copy protection method for digital information is to encrypt or save or transfer information using specific key information, and to provide a system that can be decrypted only by a user who knows the key information for decryption. Was building. Also, in the conventional encryption method using a key, the encrypted information has a completely different form from the original information before encryption. Therefore, unless the decryption using the key is performed, the original information is not encrypted at the stage of the encrypted information. You cannot know the content. Therefore, even a user who is authorized to use digital information cannot know the approximate content of the original information at the stage of encrypted information.

[0003]

In the case of a user who handles a medium protected by copy protection as described above, a user who handles a plurality of pieces of encrypted information in parallel handles information more easily in the case of selection. There is a great demand for an overview of the original information even in an encrypted state.

[0004] In addition, even for providers who provide information, even if the original information cannot be predicted from the encrypted information at all, users who are hesitant to purchase some information such as AV mosaiced. There is a merit that those who can understand the blur can stimulate the user's willingness to purchase.

[0005] Therefore, the present invention provides an encrypted state for preventing unauthorized copying and unauthorized use, which makes it possible to identify the information content after decryption to some extent, and facilitates user's information selection in the encrypted state. It is an object of the present invention to provide an information storage medium for signal-deteriorated digital information and a signal-deterioration processing method and apparatus capable of performing the above-mentioned method.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a "signal degraded state" which can be decrypted to a certain extent without converting it into information which cannot be decrypted in the encrypted state as in the prior art. The feature of the present invention resides in that information is converted into "". In the same manner as in the prior art, the decryption key is used so that the signal can be returned to the signal of the quality before deterioration after decryption.

More specifically, the following is performed. That is, in the present invention, digital information is divided in the time axis direction or the space axis direction, and the signal is degraded by using the divided blocks as a method of converting the information into a "degraded state" that can be decoded to some extent. . The following methods exist to realize this. [A] Block shuffling This is for rearranging the arrangement order of signals, such as audio information, continuous on the time axis for each block. In this case, the arrangement in the block is kept unchanged, so that a certain level of sound quality is secured, and the sound quality after block shuffling can predict the content of the original music to some extent.

When a still image is handled, the two-dimensional space is divided into meshes of a specific period, and the rearrangement and exchange between blocks are performed while the still image content in each block is maintained. [B] Perform very simple signal processing in the block.

[0009] This is a 90-degree rotation or inversion process when the object is a still image, and a time inversion when the object is audio information. [C] Perform frequency distribution processing within the block.

[0010] This performs processing on each frequency coefficient after Fourier transform or DCT transform. Specifically, the following processing is performed. (1) A mosaic is created by setting the higher-order frequency coefficient to 0, and (2) the polarity is randomly inverted with respect to the frequency coefficient.

As a special case of the above [C] "frequency coefficient polarity reversal" in the frequency distribution processing, (1) All sine (SIN) component coefficients of Fourier transform are "-1".
Is multiplied, the distribution characteristics are inverted, and
When all the dd component coefficients are multiplied by “−1”, the distribution characteristics are inverted. As can be seen from this example, the above [B] and [C]
Have a close relationship with each other.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the present invention, still image information, audio information, digital information such as video information arranged continuously on the time axis or the space axis is targeted, but for the purpose of specific and detailed embodiments, here Dolby Corporation has developed AC-3
A description will be made by taking audio information using the example.

In the following embodiment, the signal inversion processing and the block shuffling processing are used together as the signal deterioration processing method. However, the present invention is not limited to this, and it is needless to say that only one of the processing is performed. That is.

In the AC-3, one block is formed for each of 256 digital samples, and six blocks collectively form one frame. In this embodiment, this combination is used, and 6 frames in one frame are used.
Block shuffling by rearrangement within one block will be described, and a method of randomly inverting the polarity of compressed information in one block to each frequency coefficient will be described in detail.

First, the process of processing an audio signal by the processing method of the present invention will be briefly described with reference to FIG. For the audio signal, the input audio signal is sampled at a specific frequency (every 48 kHz) (step ST1), the input audio signal is divided in the time axis direction, and a block is formed for every 256 samples (step ST1). Step ST2). Next, an audio signal is DCT-transformed for each block to calculate each DCT coefficient (step ST3), and quantization processing (information compression processing) is performed on each DCT coefficient (step ST4). The polarity inversion processing is performed randomly using the result and the random polarity inversion information (step ST9). Block shuffling in a frame using the extracted block shuffling information from the signal deterioration information in parallel (rearrangement between blocks)
Processing is performed (step ST11).

The digital information whose signal has been degraded in this way is recorded on an information storage medium. Next, the above-described block shuffling and random polarity inversion processing will be described.

FIG. 2 is a diagram for explaining the block shuffling method of the present invention. In principle, as described above, in the AC-3, one block is formed for each of 256 digital samples, and six blocks are further combined to form one frame. In each block, Mantissa 6, 9 in which compressed audio information is recorded, and Expone which is level information
It consists of bit allocation information (Bit Allocation) which is bit length information of nt1,5 and Mantissa6,9. Actually, the bit length information is Exponent1,5
And calculated from the Bit Allocation information.

There are cases where two blocks are integrally formed in one frame. The part in which the plurality of blocks are reconfigured together will be referred to as a “reused block”.

In the embodiment of FIG. 2, the part of the reused block # 2 corresponds to this, and Mantissa 7 and Mantissa 8, which existed before the unitary reconfiguration, and both Bit Al
It consists of location information (position information where Mantissa 7 and 8 are recorded) and Exponent2.

In this way, two blocks are reused and 1
In the case of block (# 2), the total number of blocks per frame is 5 blocks. In the case of block shuffling (Block shuffle), this reused block is also regarded as one block, and the arrangement of the blocks is rearranged as shown in FIG. The arrangement before block shuffling is arranged in the order of reproduction along the time axis, but the audio information is divided into 256 samples (in blocks) in the time axis direction by the above-described processing. Reorder in the axial direction.

Although the audio signal itself is greatly deteriorated by the above processing, the audio signal arrangement order is maintained in the original state in the block (within 256 samples). The outline audio information content can be grasped, and the information content can be grasped at a time before the signal restoration (information decoding) is performed, and the information content can be selected as needed.

Next, a method of inverting the polarity of random DCT (discrete cosine transform) coefficients will be described. In AC-3, after sampling an audio signal, DCT conversion (a type of frequency conversion) is performed in the above-described block.
Then, signal information compression processing is performed by quantization processing for each DCT coefficient. In AC-3, 25 in the block
Six samples are converted into a sequence of 265 DCT coefficients. The DCT coefficients include a plus coefficient and a minus coefficient.

In the present invention, polarity inversion processing (DCT coefficients are randomly extracted and the coefficient values are multiplied by "-1") is performed on each of the quantized DCT coefficient values at random.
As a special case of the present invention, Odd
When the component (odd component) and the even component (even component) are separated, the polarity of the DCT coefficient value of all Odd components (odd component) is inverted while keeping the coefficient value of the even component (even component) unchanged. And the waveform in the block is inverted with respect to the time axis. This phenomenon is the same as the phenomenon in which the waveform is inverted when only sine component (sin component) at the time of Fourier transform is multiplied by “−1”. The contents of the embodiment of the present invention show a general system for the time axis inversion processing of the waveform.

FIG. 3 shows an example of signal deterioration information for controlling the polarity inversion processing and the block shuffling processing of random DCT coefficients. As shown in FIG. 3, the signal deterioration information includes polarity inversion information 21 of DCT coefficients and Block shuffle information 22.

Although not shown, this information is continuously generated by an M-sequence PN generator (random signal generator). Key information as a 4-byte control signal for signal degradation (one type of encryption) or signal restoration (one type of decryption) is recorded in a part of an information storage medium 201 (described later),
Using the key information as an initial value, the signal deterioration information is continuously generated by PN. This signal deterioration information is allocated 388 bytes per frame.

The first byte of the polarity inversion information 21 of the DCT coefficient designates a block number for inverting the polarity of the DCT coefficient. In the example of the present invention, the polarity inversion of the DCT coefficient is performed for only three or less of the six blocks (five blocks in FIG. 2) instead of performing the polarity inversion for all the blocks in one frame. That is, the first two bits of one byte specify the block number of the first target block 32 before block shuffling, the next three bits specify the block number of the second target block 33 before block shuffling, and the last three bits 3rd target block 3
The block number before block shuffling of No. 4 is designated.

At this time, the following rules are adhered to. (1) When the same block number is specified in the target Block information 31 in duplicate, the subsequent information is used. (2) Target
The block number specified in Block information 31 is 1 such as 7, 8
If the value is larger than the number of blocks in the frame, D
The polarity inversion of the CT coefficient is not performed, and the number of DCT coefficient inversion target blocks is reduced.

The following rule is followed. First target block 3
The information in 2 has 128 bytes and indicates the DCT coefficient number whose polarity is inverted for each byte. If the most significant one bit of this 1 byte is "1", the positive DC
Indicates a T coefficient, and “0” indicates a negative DCT coefficient. When the DCT coefficient numbers in the first target block 32 are duplicated, the DCT coefficient numbers are
Invert the polarity of the coefficient value.

Next, 3 bytes are allocated to the block shuffle information 22 in the signal deterioration information. In FIG.
This is specifically shown. That is, numbers are assigned to each of the six or less blocks before shuffling in one frame in order of 4 bits from the front (E, 2, 5, A, A, 9 in this example), and rearranged in ascending order of the assigned number. (In this example, 2, 3, A, A,
E, 9).

In the case of the frame structure of FIG. 2, one reus
Since there are blocks e, there are five blocks in one frame, and the last four bits of the three bytes correspond to the imaginary empty block 38.

In the example of FIG. 4, block # before shuffling is used.
4 and the number assigned to block # 5 match.
In this way, when the same number is assigned twice, the order is changed. That is, the block located before the shuffling ring is placed before.

FIG. 5 is a flowchart showing a procedure for performing the signal deterioration processing of the present invention on an audio signal. First, key information for encryption (signal degradation processing) consisting of 4 bytes is created (step ST5) and recorded in a specific area on the information storage medium. From the encrypted key information, signal deterioration information is generated by a random signal generator (step ST6), and then polarity inversion information of DCT coefficients is extracted from the signal deterioration information generated by the random signal generator (step ST7). Further, a block number corresponding to the polarity inversion and random polarity inversion information are individually extracted from the polarity inversion information of the DCT coefficient (step ST8).

For the audio signal, the input audio signal is sampled at a specific frequency (every 48 kHz) (step ST1), the input audio signal is divided in the time axis direction, and a block is formed every 256 samples. Configure (step ST2). Next, an audio signal is DCT-transformed for each block to calculate each DCT coefficient (step ST3), and quantization processing (information compression processing) is performed on each DCT coefficient (step ST4). Using the result and the random polarity inversion information extracted as described above, the polarity inversion processing is performed randomly (step ST
9). In parallel, extraction from the signal deterioration information (step S
T10) Using the block shuffling information, block shuffling (rearrangement between blocks) within the frame is performed (step ST11). The digital information whose signal has been degraded in this way is recorded on the information storage medium.

FIG. 6 is a block diagram of a digital information reproducing apparatus of the present invention for reproducing digital information from an information storage medium recorded by the above method and restoring (decoding) a signal.

The digital information reproducing apparatus of the present invention comprises an information reproducing section 42, a signal deterioration information detecting section 43, a signal restoring section 44, a decoding section 45, a speaker or an earphone 46. The information reproducing unit reproduces a signal from a recording medium such as an optical disk by an optical pickup unit. The reproduced signal is supplied to a signal restoration unit 44 and a signal deterioration information detection unit 43.
Is input to The signal deterioration information detection unit 43 generates the PN using the key information as described above, and recognizes the signal deterioration information as described with reference to FIG. 3 based on this.
Based on the signal deterioration information, a signal for performing signal restoration is created and supplied to the signal restoration unit 44. Then, here, the block shuffling is released, and the polarity inversion portion of the DCT coefficient is restored. The restored signal is input to the decoding unit 45, where decoding is performed by PCM, MPEG, or AC-3. The decoded signal is supplied to a speaker or an earphone.

FIG. 7 shows the signal deterioration information detecting section 43 described above.
2 shows the internal configuration of the in more detail. First, key information is detected from a signal read from a disk. Based on this key information, the signal deterioration information
The signal deterioration information described above is generated. Using this signal deterioration information, the polarity inversion information of the DCT coefficient and the block shuffle information are extracted in the DCT coefficient inversion information extraction unit 48 and the block shuffle information extraction unit 49, and are used for restoration.

FIG. 8 shows a process of reading out the audio information whose signal has been deteriorated from the information storage medium and outputting the restored signal. The information reproducing unit 42 reproduces the key information from the information storage medium, and the key information extracting unit 50 extracts the key information for restoring the deteriorated digital information (step ST2).
1) As a step, key information is read from the information storage medium by the information reproducing unit 42 and sent to the signal deterioration information detecting unit 43.
The key information extraction unit 50 in the signal deterioration information detection unit 43
To receive key information. Next, as a step of reproducing the signal deterioration information by the signal deterioration information generating section 47 (step ST22), the signal deterioration information generating section 47 generates the signal deterioration information.
The signal deterioration information generating section 47 is composed of an M-sequence PN random signal generator, and continuously generates signal deterioration information by inputting 4-byte key information as an initial value. Next, from the signal deterioration information, the polarity inversion information 21 of the DCT coefficient is extracted by the DCT coefficient inversion information extraction unit 48 (step ST23), and the DCT coefficient is inverted by the signal restoration unit 44.
The polarity of the coefficient is restored (step ST25). In parallel with this, the block shuffle information extraction unit 49 extracts the block shuffle information 22 from the signal deterioration information (step ST2).
4) Then, the order of the blocks shuffled by the signal restoration unit 44 is restored (step ST26). Thereafter, the compressed digital signal restored by the decoding unit 45 is decoded (step ST27), and the decoded audio information is output to a speaker or an earphone (step ST2).
8).

FIG. 9 shows the configuration of the information reproducing apparatus. The function of the information reproducing unit will be described. The basic functions of the information recording / reproducing unit will be described below.

In the information recording / reproducing section, new information can be recorded or rewritten (including erasure of information) by using a focused spot at a predetermined position on the information storage medium (optical disc) 201. Information storage media (optical disks)
The information already recorded can be reproduced from a predetermined position on the image 201 by using the converging spot.

Next, the means for achieving the basic function of the information recording / reproducing unit will be described as follows. As a means for achieving the above basic functions, the information recording / reproducing unit includes an information storage medium 201.
The focused spot is traced (followed) along an upper track (not shown). Further, by changing the amount of light of the converging spot irradiating the information storage medium 201, information recording /
Switch between play and erase. Further, it converts the externally applied recording signal d into an optimum signal for recording at a high density and a low error rate.

The structure of the mechanism section and the operation of the detection section will be described. First, the basic structure of the optical head 202 and the signal detection circuit will be described. Signal detection by optical head 202: The optical head 202 basically includes a semiconductor laser element as a light source, a photodetector, and an objective lens, though not shown. Laser light emitted from the semiconductor laser element is focused on an information storage medium (optical disk) 201 by an objective lens. The laser light reflected by the light reflection film or light reflection recording film of the information storage medium (optical disk) 201 is photoelectrically converted by a photodetector.

The detection current obtained by the photodetector is supplied to an amplifier 21
3 is subjected to current-voltage conversion to become a detection signal. This detection signal is processed by the focus / track error detection circuit 217 or the binarization circuit 212. Generally, a photodetector is divided into a plurality of photodetection areas, and individually detects a change in the amount of light applied to each photodetection area. The focus / track error detection circuit 2
In step 17, the sum / difference is calculated to detect a focus shift and a track shift. A signal on the information storage medium 201 is reproduced by detecting a change in the amount of light reflected from the light reflection film or the light reflective recording film of the information storage medium (optical disc) 201.

A method of detecting a focus shift will be described. As a method of optically detecting the amount of focus shift, an astigmatism method: not shown in the detection optical path of the laser beam reflected by the light reflection film or the light reflection recording film of the information storage medium (optical disk) 201, This is a method of arranging an optical element for generating astigmatism and detecting a shape change of a laser beam irradiated on a photodetector.

The light detection area is divided into four diagonally. The focus / track error detection circuit 217 calculates the difference between the diagonal sums of the detection signals obtained from the respective detection areas to obtain a focus error detection signal. Alternatively, the knife edge method: a method of arranging a knife edge that asymmetrically shields a part of the laser light reflected by the information storage medium 201. The light detection area is divided into two parts, and a difference between detection signals obtained from each detection area is obtained to obtain a focus error detection signal. Often use either.

A method of detecting a track shift will be described.
The information storage medium (optical disk) 201 has a spiral or concentric track, and information is recorded on the track. Information is reproduced or recorded / erased by tracing the focused spot along this track. In order to stably trace the focal spot along the track,
It is necessary to optically detect the relative displacement between the track and the condensing spot.

As a method of detecting a track shift, a DPD (Differential Phase Detection) method is generally used: an intensity distribution on a photodetector of a laser beam reflected by a light reflection film or a light reflection recording film of an information storage medium (optical disk) 201. Detect changes. The light detection area is divided into four diagonally. The difference between the diagonal sums of the detection signals obtained from the respective detection areas in the focus / track error detection circuit 217 is obtained to obtain a track error detection signal. Alternatively, a Push-Pull method: a change in intensity distribution of a laser beam reflected by the information storage medium 201 on a photodetector is detected. The light detection area is divided into two parts, and a track error detection signal is obtained by taking the difference between the detection signals obtained from each detection area.

Twin-Spot method: A diffractive element or the like is arranged in a light transmission system between a semiconductor laser element and an information storage medium 201 to split light into a plurality of wavefronts, and to irradiate the information storage medium 201 with ± 1st order diffracted light. A change in the amount of reflected light is detected. A light detection area for individually detecting the reflected light amount of the + 1st-order diffracted light and the reflected light amount of the -1st-order diffracted light is arranged separately from the light detection area for detecting the reproduction signal. Get. and so on.

The structure of the objective lens actuator will be described. An objective lens (not shown) for condensing the laser light emitted from the semiconductor laser element on the information storage medium 201 has a structure capable of moving in two axial directions according to the output current of the objective lens actuator drive circuit 218. ing.

The moving direction of the objective lens moves in a direction perpendicular to the information storage medium 201 for focus shift correction, and moves in a radial direction of the information storage medium 201 for track shift correction. Although not shown, the moving mechanism of the objective lens is called an objective lens actuator.

As the objective lens actuator structure, a shaft sliding method is a method in which a blade integral with the objective lens moves along a central axis (shaft).
A method in which the blade moves in the direction along the center axis to correct the focus shift, and corrects the track shift by rotating the blade with respect to the center axis, or a four-wire method: the blade integrated with the objective lens is a fixed system. In this case, a method of moving the blade in two axial directions using elastic deformation of the wire is often used.

Each method has a permanent magnet and a coil,
The blade is moved by passing a current through a coil connected to the blade. Information storage medium 201
The rotation control system will be described.

An information storage medium (optical disk) 201 is mounted on a rotary table 221 which is rotated by the driving force of a spindle motor 204. The number of rotations of the information storage medium 201 is detected by a reproduction signal obtained from the information storage medium 201. That is, the detection signal (analog signal) output from the amplifier 213 is converted into a digital signal by the binarization circuit 212, and a fixed cycle signal (reference clock signal) is generated from the signal by the PLL circuit 211. The information storage medium rotation speed detection circuit 214 detects the number of rotations of the information storage medium 201 using this signal and outputs the value.

A correspondence table of the number of rotations of the information storage medium corresponding to the radial position to be reproduced or recorded / erased on the information storage medium 201 is recorded in the semiconductor memory 219 in advance. When the reproduction position or the recording / erasing position is determined, the control circuit 220 sets the target rotation speed of the information storage medium 201 with reference to the information in the semiconductor memory 219, and notifies the spindle motor drive circuit 215 of the value.

The spindle motor drive circuit 215 obtains a difference between the target rotation speed and the output signal (current rotation speed) of the information storage medium rotation speed detection circuit 214, and outputs a drive current according to the result to the spindle motor 204. And the control is performed so that the number of rotations of the spindle motor 204 becomes constant. The output signal of the information storage medium rotation speed detection circuit 214 is a pulse signal having a frequency corresponding to the rotation speed of the information storage medium 201, and the spindle motor drive circuit 215 controls both the frequency and the pulse phase of this signal.

The optical head moving mechanism will be described. An optical head moving mechanism (feed motor) 203 for moving the optical head 202 in the radial direction of the information storage medium 201 is provided. In many cases, a rod-shaped guide shaft is used as a guide mechanism for moving the optical head 202, and the optical head 202 moves using friction between the guide shaft and a bush attached to a part of the optical head 202. In addition, there is a method of using a bearing in which a frictional force is reduced by using a rotary motion.

Although a driving force transmitting method for moving the optical head 202 is not shown, a rotating motor having a pinion (rotating gear) is arranged in a fixed system, and a rack, which is a linear gear meshing with the pinion, is mounted on the optical head 202. And converts the rotary motion of the rotary motor into a linear motion of the optical head 202. As another driving force transmission method, a linear motor system in which a permanent magnet is arranged in a fixed system and current flows in a coil arranged in the optical head 202 to move the coil in a linear direction may be used.

In both the rotary motor and the linear motor, basically, a current is supplied to the feed motor to
A driving force for two movements is generated. This drive current is supplied from the feed motor drive circuit 216.

The function of each control circuit will be described. Focusing spot trace control; focus / track correction
Output signal (detection signal) of the track error detection circuit 217
A circuit that supplies a drive current to an objective lens actuator (not shown) in the optical head 202 according to the above is the objective lens actuator drive circuit 218. A phase compensating circuit for improving characteristics in accordance with the frequency characteristics of the objective lens actuator is provided inside in order to make the movement of the objective lens respond quickly at a high frequency range.

The objective lens actuator drive circuit 218
Then, the focus / track shift correction operation (focus / track loop) is turned on in response to a command from the control circuit 220.
/ OFF processing, processing for moving the objective lens in the vertical direction (focus direction) of the information storage medium 201 at low speed (executed when the focus / track loop is OFF), and radial direction of the information storage medium 201 (crossing the track using a kick pulse) Direction) to slightly move the focused spot to the next track.

The laser light quantity control will be described. First, the switching process between reproduction and recording / erasing will be described. Switching between reproduction and recording / erasing is performed by changing the amount of light of a focused spot irradiated onto the information storage medium 201.

For an information storage medium using the phase change method, the relationship of [light amount at the time of recording]> [light amount at the time of erasing]> [light amount at the time of reproduction] is generally established, and the magneto-optical method is used. In general, the information storage medium has a relationship of [light quantity at the time of recording] [light quantity at the time of erasing]> [light quantity at the time of reproduction]. In the case of the magneto-optical method, an external magnetic field applied to the information storage medium 201 during recording / erasing (not shown)
The recording and erasing processes are controlled by changing the polarity of the data.

At the time of reproducing information, a constant amount of light is continuously irradiated on the information storage medium 201. When recording new information, the pulsed intermittent light amount is added to the light amount at the time of reproduction. When the semiconductor laser element emits a pulse with a large amount of light, the light reflective recording film of the information storage medium 201 locally causes an optical change or a shape change,
A recording mark is formed. Similarly, when overwriting an already recorded area, the semiconductor laser element emits a pulse.

When erasing already recorded information, a constant light amount larger than that at the time of reproduction is continuously irradiated. When erasing information continuously, the irradiation light amount is returned at the time of reproduction in a specific cycle such as a sector unit, and the information is intermittently reproduced in parallel with the erasing process. The track number and address of the track to be intermittently erased are reproduced, and the erasing process is performed while confirming that there is no error in the erased track.

The laser emission control will be described. Although not shown, the optical head 202 has a built-in photodetector for detecting the light emission amount of the semiconductor laser element. The semiconductor laser driving circuit 205 calculates the difference between the photodetector output (detection signal of the light emission amount of the semiconductor laser element) and the light emission reference signal given from the recording / reproducing / erasing control waveform generating circuit 206, and based on the result, The drive current to the laser is fed back.

Various operations related to the control system of the mechanism will be described. First, start control will be described. When the information storage medium (optical disk) 201 is mounted on the turntable 221 and start control is started, processing is performed according to the following procedure. 1) From the control circuit 220 to the spindle motor drive circuit 2
The target rotation speed is transmitted to 15, a drive current is supplied from the spindle motor drive circuit 215 to the spindle motor 204, and the rotation of the spindle motor 204 starts. 2) At the same time, feed motor drive circuit 2 from control circuit 220
A command (execution command) is issued to the optical head 202, and a drive current is supplied from the feed motor drive circuit 216 to the optical head drive mechanism (feed motor) 203 so that the optical head 202
Moves to the innermost position of the information storage medium 201. It is confirmed that the optical head 202 is located further inward of the information storage medium 201 beyond the area where the information is recorded. 3) When the spindle motor 204 reaches the target number of revolutions, its status (status report) is output to the control circuit 220. 4) A current is supplied from the semiconductor laser driving circuit 205 to the semiconductor laser element in the optical head 202 according to the reproduced light amount signal sent from the control circuit 220 to the recording / reproducing / erasing control waveform generation circuit 206, and laser emission is started. I do. * The optimum irradiation light amount at the time of reproduction differs depending on the type of the information storage medium (optical disk) 201. At the time of startup, it is set to the value with the lowest irradiation light amount. 5) In accordance with a command from the control circuit 220, an objective lens (not shown) in the optical head 202 is shifted to a position farthest from the information storage medium 201, and an objective lens actuator is moved so that the objective lens slowly approaches the information storage medium 201. The drive circuit 218 controls. 6) At the same time, the focus / track error detection circuit 217
To monitor the amount of defocus, and output a status when the objective lens comes near the in-focus position, and output the status to the control circuit 2.
Notify 20. 7) Upon receiving the notice, the control circuit 220 issues a command to the objective lens actuator drive circuit 218 to turn on the focus loop. 8) The control circuit 220 issues a command to the feed motor drive circuit 216 while keeping the focus loop ON to move the optical head 202 slowly toward the outer peripheral portion of the information storage medium 201. 9) At the same time, the reproduction signal from the optical head 202 is monitored, and when the optical head 202 reaches the recording area on the information storage medium 201, the movement of the optical head 202 is stopped, and the track loop is turned on for the objective lens actuator drive circuit 218. Issue a command that causes 10) The “optimum light amount at the time of reproduction” and the “optimum light amount at the time of recording / erasing” recorded on the inner peripheral portion of the information storage medium (optical disk) 201 are reproduced. Recorded in the memory 219. 11) Further, the control circuit 220 sends a signal corresponding to the "optimum light amount at the time of reproduction" to the recording / reproduction / erase control waveform generation circuit 206 to reset the light emission amount of the semiconductor laser element at the time of reproduction. 12) The light emission amount of the semiconductor laser element at the time of recording / erasing is set according to the “optimum light amount at the time of recording / erasing” recorded on the information storage medium 201.

The access control will be described. Regarding reproduction of access destination information on the information storage medium 201; information on what kind of information is stored in which location on the information storage medium 201 differs depending on the type of the information storage medium 201, and The directory management area in the information storage medium 201 is recorded collectively in the inner circumference area or the outer circumference area of the information storage medium 201, or the navigation pack is an MPEG2 PS (Program S).
VOAM (Video Ob) that conforms to the data structure of
ject Set), and information such as information on where the next video is recorded is recorded.

When it is desired to reproduce or record / delete specific information, the information in the above-mentioned area is reproduced first, and the access destination is determined from the obtained information. The coarse access control will be described.

The control circuit 220 calculates the radius position of the access destination by calculation, and calculates the distance from the current position of the optical head 202. Speed curve information that can be reached in the shortest time with respect to the moving distance of the optical head 202 is recorded in the semiconductor memory 219 in advance. The control circuit 220 reads the information and controls the movement of the optical head 202 in the following manner according to the speed curve.

After the track loop is turned off by issuing a command from the control circuit 220 to the objective lens actuator drive circuit 218, the feed motor drive circuit 216
To start the movement of the optical head 202.

When the focused spot crosses a track on the information storage medium 201, a track error detection signal is generated in the focus / track error detection circuit 217. Using this track error detection signal, the relative speed of the focused spot with respect to the information storage medium 201 can be detected.

The feed motor drive circuit 216 calculates the difference between the relative speed of the condensed spot obtained from the focus / track error detection circuit 217 and the target speed information sent one by one from the control circuit 220, and uses the result as the optical head. The optical head 202 is moved while applying feedback to the drive current to the drive mechanism (feed motor) 203.

As described in the item "Optical head moving mechanism", frictional force always acts between the guide shaft and the bush or bearing. When the optical head 202 is moving at high speed, kinetic friction is applied. However, at the start of movement and immediately before the stop, the moving speed of the optical head 202 is low, and static friction is applied. At this time, since the relative frictional force is increasing (especially immediately before the stop), the amplification factor (gain) of the current supplied to the optical head driving mechanism (feed motor) 203 is increased in response to a command from the control circuit 220. .

The fine access control will be described. When the optical head 202 reaches the target position, the control unit 220 issues a command to the objective lens actuator drive circuit 218 to turn on the track loop.

The focused spot reproduces the address or track number of that portion while tracing along the track on the information storage medium 201. The current focus spot position is calculated from the address or track number there, and the number of error tracks from the target position is determined by the control unit 220.
And notifies the objective lens actuator drive circuit 218 of the number of tracks required for moving the focused spot.

Objective lens actuator drive circuit 21
When one set of kick pulses is generated in 8, the objective lens slightly moves in the radial direction of the information storage medium 201, and the focused spot moves to the next track.

Objective lens actuator drive circuit 21
In FIG. 8, the track loop is temporarily turned off, the number of kick pulses generated according to the information from the control circuit 220 is generated, and then the track loop is turned on again.

After the end of the fine access, the control circuit 220 reproduces information (address or track number) of the position where the focused spot is traced, and confirms that the target track is being accessed.

The continuous recording / reproducing / erasing control will be described. The track error detection signal output from the focus / track error detection circuit 217 is input to the feed motor drive circuit 216. The control circuit 220 controls the feed motor drive circuit 216 so as not to use the track error detection signal during the “start control” and the “access control” described above.

After confirming that the focused spot has reached the target track by access, a part of the track error detection signal is transmitted to the optical head driving mechanism (feed motor) by the command from the control circuit 220 via the motor driving circuit 216. ) 203 is supplied as a drive current. This control is continued during the period in which the reproduction or the recording / erasing process is continuously performed.

The information storage medium 201 is mounted with an eccentricity slightly shifted from the center position of the turntable 221. When a part of the track error detection signal is supplied as a drive current, the optical head 202 is adjusted in accordance with the eccentricity.
The whole moves slightly.

When the reproduction or recording / erasing process is performed continuously for a long time, the position of the focused spot gradually moves in the outer circumferential direction or the inner circumferential direction. When a part of the track error detection signal is supplied as a drive current to the optical head moving mechanism (feed motor) 203, the optical head 202 gradually moves in the outer circumferential direction or the inner circumferential direction accordingly.

In this way, the burden of correcting the track shift of the objective lens actuator can be reduced, and the track loop can be stabilized. The termination control will be described.

When a series of processing is completed and the operation is to be ended, the processing is performed according to the following procedure. 1) The control unit 220 issues a command to the objective lens actuator drive circuit 218 to turn off the track loop. 2) The control circuit 220 issues a command to the objective lens actuator drive circuit 218 to turn off the focus loop. 3) The control circuit 220 issues a command to the recording / reproduction / erase control waveform generation circuit 206 to stop the light emission of the semiconductor laser device. 4) Notify the spindle motor drive circuit 215 of 0 as the reference rotation speed.

The flow of the recording signal / reproduction signal to the information storage medium will be described. The signal format recorded on the information storage medium 201 will be described. A signal recorded on the information storage medium 201 can be corrected for a recording information error caused by a defect on the information storage medium 201. The DC component of the reproduction signal is set to 0 to simplify the reproduction processing circuit. In order to satisfy the requirement of recording information on the information storage medium 201 as densely as possible, the information recording / reproducing unit (physical block) adds “error correction function”, “signal conversion for recorded information (signal Modulation and demodulation).

The signal flow during recording will be described. ECC (Error Correction Code) addition processing;
The information to be recorded on the information storage medium 201 is recorded as a recording signal d in the form of a raw signal.
2 is input. This recording signal d is recorded as it is in the semiconductor memory 219, and then the ECC encoding circuit 208 performs the following ECC addition processing.

An embodiment of an ECC adding method using a product code will be described below. The recording signal d is stored in the semiconductor memory 2
One row is sequentially arranged every 172 bytes in 19, and one set of ECC blocks is formed with 192 rows. This "row: 172x
Column: For a raw signal (recording signal d) in a set of ECC blocks composed of 192 bytes ”, an inner code PI of 10 bytes is calculated for each row of 172 bytes to obtain a semiconductor memory 2.
Additional recording is made within 19. Further, the outer code PO of 16 Bytes is calculated for each column of the Bytes unit, and the semiconductor memory 219 is calculated.
Additional record within.

As an embodiment of recording on the information storage medium 201, a total of 2366 Bytes (2366 = (12 + 1) × (172 + 10)) of 12 lines including the inner code PI and one line for the outer code PO is used as a unit. Record within one sector.

When the addition of the inner code PI and the outer code PO is completed, the ECC encoding circuit 208 reads a signal of 2366 bytes for one sector from the semiconductor memory 219 and transfers it to the modulation circuit 207.

Next, signal modulation will be described. The DC component (DSV: Digital Sum Value) of the reproduced signal is approached to 0,
In order to record information on the information storage medium 201 at high density, signal modulation, which is conversion of a signal format, is performed in the modulation circuit 207.

A conversion table indicating the relationship between the original signal and the modulated signal is provided inside the modulation circuit 207 and the demodulation circuit 210. The signal transferred from the ECC encoding circuit 208 is divided into a plurality of bits according to the modulation scheme, and converted into another signal (code) with reference to a conversion table.

For example, 8/16 modulation (R
When the LL (2, 10) code is used, there are two types of conversion tables, and the DC component (DSV: Dis
The reference conversion table is switched one by one so that italSum Value) approaches zero.

The generation of a recording waveform will be described. When a recording mark is recorded on the information storage medium (optical disk) 201, generally, as a recording method, a mark length recording method: "1" comes at the front end position and the rear terminal position of the recording mark.

Recording method between marks: The center position of the recording mark coincides with the position of "1". There are two types. When mark length recording is performed, it is necessary to form a long recording mark. In this case, if the recording light amount is continuously irradiated for a certain period, a “raindrop” recording mark having a wide width only at the rear portion is formed due to the heat storage effect of the light reflective recording film of the information storage medium 201. In order to eliminate this adverse effect, when forming a long recording mark, the recording mark is divided into a plurality of recording pulses or the recording waveform is changed stepwise.

Recording / reproducing / erasing control waveform generating circuit 206
Inside, the above-described recording waveform is created in accordance with the recording signal sent from the modulation circuit 207 and transmitted to the semiconductor laser driving circuit 205.

The flow of signals during reproduction will be described. Binarization / PLL circuit; “Optical head 202”
As described in the item of “Signal Detection by”, a change in the amount of light reflected from the light reflecting film or the light reflective recording film of the information storage medium (optical disk) 201 is detected, and the signal on the information storage medium 201 is reproduced. The signal obtained in step (1) has an analog waveform, and the binarization circuit 212 converts the signal into a binary digital signal consisting of "1" and "0" using a comparator.

A reference signal at the time of reproducing information is extracted by the PLL circuit 211 from the obtained reproduction signal. PL
The L circuit 211 has a built-in variable frequency oscillator. The frequency and phase between the pulse signal (reference clock) output from the oscillator and the output signal of the binarization circuit 212 are compared, and the result is fed back to the oscillator output.

The demodulation of a signal will be described. The demodulation circuit 210 has a conversion table indicating the relationship between the modulated signal and the demodulated signal. The signal is returned to the original signal while referring to the conversion table in accordance with the reference clock obtained by the PLL circuit 211. The returned (demodulated) signal is recorded in the semiconductor memory 219.

The error correction processing will be described. The error correction circuit 209 detects an error portion of the signal stored in the semiconductor memory 219 using the inner code PI and the outer code PO, and sets a pointer flag of the error portion. Thereafter, while reading the signal from the semiconductor memory 219, the signal at the error location is sequentially corrected in accordance with the error pointer flag, the inner code PI and the outer code PO are removed, and the signal is transferred to the data input / output interface unit 222. ECC
The signal sent from the encoding circuit 208 is converted into a reproduced signal c from the data input / output interface unit 222.
Output as

As described above, the use of the method according to the embodiment of the present invention not only prevents inadvertent unauthorized copying or unauthorized use of digital information, but also reduces the signal degradation to some extent from the digital information itself after signal degradation (after loose encryption). The previous information can be inferred. Therefore, it is possible to perform high-speed selection (information filtering) by inferring the digital information content to some extent from the digital information in the stored state or the transmission state without performing complicated decoding processing.

[0100]

As described above, according to the present invention,
In the state of encryption to prevent unauthorized copying and unauthorized use,
It is possible to provide an information storage medium for signal-deteriorated digital information and a signal-deterioration processing method and apparatus capable of identifying the information content to some extent after decryption and facilitating selection of information by a user in an encrypted state.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of a signal processing method according to the present invention.

FIG. 2 is a diagram showing an example of block shuffling used in the present invention.

FIG. 3 is a diagram showing an example of the structure of signal deterioration information used in the present invention.

FIG. 4 is a diagram showing an example of block shuffle using block shuffle information used in the present invention.

FIG. 5 is a flowchart showing an overall flow of signal processing according to the present invention.

FIG. 6 is a diagram showing a configuration example of a digital information reproducing apparatus according to the present invention.

FIG. 7 is a diagram illustrating a configuration example of a signal deterioration information detection unit in FIG. 6;

FIG. 8 is a flowchart shown to explain the operation of the digital information reproducing apparatus according to the present invention.

FIG. 9 is a diagram showing an example of the overall configuration of a digital information reproducing apparatus according to the present invention.

[Explanation of symbols]

201 optical disc, 202 optical head, 203 optical head moving mechanism, 204 spindle motor, 205
Semiconductor laser drive circuit, 206: recording / reproduction / erasure control waveform generation circuit, 207: modulation circuit, 208: ECC encoding circuit, 209: error correction circuit, 210 ...
Demodulation circuit, 211 ... PLL circuit, 212 ... binarization circuit,
213 amplifier, 214 rotational speed detection circuit, 215
Spindle motor drive circuit, 216: feed motor drive circuit, 217: focus track error detection circuit, 21
8: Objective lens actuator drive circuit, 219: Semiconductor memory, 220: Control circuit, 222: Data input / output interface.

Claims (12)

[Claims] 1. A first division method for dividing digital information having signal information arranged along a time axis or a space axis according to the time axis or the space axis, and a second method for deteriorating the signal characteristics. The digital information before signal deterioration is divided in the time axis direction or the space axis direction by the first division method. A signal deterioration processing method for digital information, wherein a signal is deteriorated by converting digital information by a second signal deterioration method. 2. The digital information divided in the time axis direction or the space axis direction by the first division method, in the time axis direction or in the block of the digital information divided by the second signal deterioration method. 2. The signal deterioration processing method for digital information according to claim 1, wherein the signal is rearranged in the direction of the space axis to deteriorate the signal. 3. In the second signal deterioration method, a signal is converted into a frequency distribution in the time axis direction or the space axis direction for each block of the divided digital information, and each frequency coefficient is randomly determined. 2. The method according to claim 1, wherein the signal is degraded by inverting the polarity. 4. The signal deterioration processing of digital information according to claim 1, wherein the signal distribution is inverted in the time axis direction or the space axis direction for each of the blocks of the divided digital information in the second signal deterioration method. Method. 5. An information storage medium on which digital information subjected to signal degradation processing by the method of claim 1 is recorded. 6. An information storage medium on which digital information subjected to signal deterioration processing by the method according to claim 2 is recorded. 7. An information storage medium on which digital information subjected to signal deterioration processing by the method according to claim 3 is recorded. 8. An information storage medium on which digital information subjected to signal deterioration processing by the method according to claim 4 is recorded. 9. A signal deterioration information detecting section for restoring signal deterioration of digital information divided for each block and subjected to signal deterioration processing, and information detected by the signal deterioration information detecting section is provided. Digital information comprising: a signal restoration unit for restoring digital information having a base signal deteriorated to a state before deterioration; and a decoding unit for compressed digital information obtained from the signal restoration unit. Playback device. 10. A means for dividing digital information before signal degradation in a time axis and / or space axis direction into blocks in accordance with a time axis and / or a space axis and DCT transforming the block signal. Means for further quantizing; means for randomly inverting the polarity of the quantized DCT coefficient; means for block shuffling in the frame with respect to the block subjected to the polarity processing; Means for creating key information for canceling block shuffling and reversal of polarity. 11. The digital signal before signal degradation is arranged along the time axis and / or the space axis, divided into blocks in the time axis and / or the space axis direction, and is divided into blocks. The DCT coefficients after quantization are subjected to random polarity inversion processing, and the blocks subjected to this polarity processing are further subjected to block shuffling within a frame. And an information recording medium in which key information for canceling the block shuffling and the polarity inversion is recorded as a control signal. 12. The digital signal before signal degradation is arranged along the time axis and / or the spatial axis, divided into blocks in the time axis and / or the spatial axis direction, and is divided into blocks. The DCT coefficients after quantization are subjected to random polarity inversion processing, and the blocks subjected to this polarity processing are further subjected to block shuffling within a frame. Is applied to a data recording signal, the block shuffling, the key information for releasing the polarity inversion as a control signal is a device that reproduces an information recording medium recorded as a control signal, from the control signal the key Information, and using the key information, a restoring means for canceling the block shuffling and the polarity reversal of the data recording signal. Storage medium reproducing apparatus.