JPS6019048B2 - Information reproducing method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for recording information such as video, audio signals, computer data, etc. at high density on a recording medium, and accurately reading and reproducing desired information.

In particular, information such as video signals and computer data is modulated into binary form, and is recorded on a recording medium, such as a disk, in a non-contact manner, with high density unevenness, or in the form of shading, and an irradiation beam such as a light beam is transmitted. The present invention relates to an information retrieval device that uses a contactless and accurate method to reproduce desired information. Such an information retrieval device detects an information book containing the necessary information from among the densely recorded information, moves the irradiation beam to the above position, and retrieves only the necessary information. must be accurately extracted and played. As a solution to this problem, when reproducing a disc in which information grooves on which information is recorded are concentrically recorded on the disc, conventionally, as detailed in Tsubaki Sekisho 49 Ichisuji 614, the TV image is A signal indicating the order of the information grooves is inserted into one part of one information groove corresponding to one frame (within the direct retrace period), and the light beam is moved to the vicinity of the desired information groove during playback, and the desired information groove is A signal indicating the order of the information grooves is detected by pulling a light beam to position it in one nearby information groove, then performing tracking to track the information groove, and reproducing the information recorded in the information groove. This method detects the deviation from the desired information groove and moves the light beam to the information groove where the desired information is recorded.

However, this method traces an information groove that is different from the desired information groove at least once to find the desired information groove.
A signal indicating the order must be detected. Therefore, there is a problem in that it takes a very long time to reproduce information from a desired information groove. The present invention aims to solve the above-mentioned problems in a method of searching for desired information using an information recording/reproducing device.

That is, in the present invention, a rotating recording medium is irradiated with an irradiation beam modulated by an information signal to form a plurality of information grooves along the rotation direction, and a light beam is irradiated onto the rotating recording medium. In the information reproducing method of converting the reflected light or transmitted light into an electric signal and reproducing the information signal, the plurality of information grooves are divided into blocks for each of the plurality of adjacent information grooves, and within each block, each block is divided into blocks. A standard signal having a different frequency for each information groove is superimposed on the information signal, and the light beam is positioned near the desired information groove by a signal indicating the block address to which the desired information groove belongs, and the electric light beam is positioned near the desired information groove. The standard signal detected from the signal is compared with the standard signal corresponding to the desired information groove, and thereby the light beam is positioned in the desired information groove to obtain the information recorded in the desired information groove. It is characterized by reproducing rut signals. To outline the invention,
Regarding the tracking method, the patent No. 48-12968 "Information recording and reproducing method and apparatus" (see Japanese Patent Publication No. 54-15727), which was previously filed by the present inventors, is used, but the following method is used. There is no problem in implementing the present invention using other tracking methods. In addition, regarding retraction, the present inventors applied for the special face 50-9
Specification No. 721 "Automatic retraction method" (Samurai Kosho 55-1
825)). Therefore, the information retrieval method and apparatus will be mainly explained here. The principle of the present invention will be explained below. In order to search for a desired information groove from a medium on which information is recorded at high density using light, it is necessary to see all the information grooves in the field of view of the objective lens for Shuto (the range on the medium that the objective lens can see). Since this is not possible, first make sure that the desired information groove is within the field of view of the focusing objective lens. Second, the desired information groove is distinguished from other information grooves within the field of view. Moreover, it is necessary to perform the above operations in a short period of time. Therefore, regarding the first point, the setting error of the objective lens is made smaller than the field of view.
This is easily achieved by selecting a moving mechanism for the optical system including the objective lens. For example, if a computer disk moving mechanism that moves the head by about 600 degrees is used, the positioning accuracy will be about 20 degrees. Since the field of view of the objective lens is usually about 500 r, the first requirement can be satisfied. Regarding the second method, the frequency of micro-vibration in the direction perpendicular to the direction of movement of the information groove used for tracking operation to accurately track the information groove is changed for each information groove within the field of view. Distinguish information grooves by detecting them. Hereinafter, the content of the present invention will be described in detail. In the present invention, in order to accurately perform tracking, pull-in, and information groove search during playback, a synchronization detection standard signal is added to the information signal to be recorded and played back during recording, and then FM modulation and pulse width modulation are performed. , perform meaningful modulation as phase information such as pulse position modulation (hereinafter referred to as binary modulation), and use a light beam, electron beam, etc. (hereinafter referred to as irradiation) to process the recording medium using the modulated signal. (collectively referred to as a beam) is intensity modulated. Next, using a signal having the same frequency and phase as the standard signal for synchronization detection, the intensity-modulated processing beam is slightly vibrated in a direction perpendicular to the traveling direction of the information groove to be created, and a moving recording is performed. Irradiate onto the medium. Preferably, in order to reduce crosstalk in the reproduced image, the amplitude of the microvibration is set to be less than half the sum of the width of the recorded information groove and the width of the reproduction spot. In such a state, in the present invention, the frequency of the synchronization detection standard signal is changed continuously or discontinuously to create an information groove. Here, discontinuous means that the frequency of the synchronization detection standard signal of the information signal recorded in the information groove of a certain length and the frequency of minute vibrations of the information groove are the same. In particular, the constant length information groove is generally equal to a unit information groove. Here, the unit information groove means a case where the information signal recorded there has a series of meanings. For example, if the information to be recorded is a television signal, one frame's worth of information may be considered. In general, the unit information grooves are formed substantially parallel to each other. Taking a disk as a recording medium, a case will be described in which the synchronization detection standard signal is changed discontinuously as described above. First, select an appropriate number (assuming n) according to the order in which all unit information grooves to be recorded are recorded.
The unit information grooves are grouped together into one block, and the entire recording information groove is divided into N blocks. In one block, the position of the irradiation beam is stopped at one point in the radial direction of the disk during one rotation of the disk, and the above recording is performed using a synchronous detection standard signal of a certain frequency.

Next, in the same way, while moving the irradiation beam discontinuously in the radial direction of the disk at a pitch interval of 6 degrees, synchronization is detected every time the irradiation position of the optical beam in the disk radial direction changes, that is, for each unit information groove. The above recording is performed by changing the frequency of the standard signal at frequency intervals Δf.As a result, the disc on which information is recorded becomes as shown in FIG.
The information grooves on the disk 1 form concentric circles with a pitch interval of 6 mm. Although not shown in the figure, n information grooves are lined up from the first information horizontal 3 to the last information groove of a certain block. Based on the frequency of the synchronization detection standard signal of the first information groove 3 (the frequency of minute vibrations in the direction perpendicular to the direction of movement of the information groove), the frequency of the synchronization detection standard signal of the last information groove 4 is ten (n- 1)×△f. For each block composed of n pieces of information, there is a change in the synchronization detection standard signal for each information groove as described above. Further, the center of rotation of the disk 1 is indicated by 2. From FIG. 1, a specific disc-shaped information groove corresponds to a specific frequency of a synchronization detection standard signal in a specific block. Furthermore, as another recording method, the above recording is performed by continuously changing the position of the irradiation beam in the disk radial direction at a constant speed, and simultaneously changing the frequency of the synchronization detection standard signal either continuously or discontinuously. There are ways to do it.

As a result, the information groove in which information is recorded forms a spiral shape on the disk, and by detecting the synchronization detection standard signal recorded in the information groove, the information groove being reproduced is determined from the number of the information groove from the beginning of the block. It turns out that it is. Next, we will describe the principle of searching out an information groove in which desired information is recorded from a recording medium such as a disc or a disc sheet on which information has been recorded by the method described above and reproducing it accurately. First, specify which block the information groove in which the desired information is recorded belongs to and what number from the beginning of the block it is. To do this, store in advance the unit information groove in which specific information is recorded, the block number, and the number within the block in a storage device, etc., so that the desired information is only the block number and the number within the block. It must be expressed as . By specifying the block number corresponding to the desired information and the number of the information groove within the block, the position on the disk of the information groove in which the desired information is recorded is determined. Next, the light beam is moved to the above position in a direction perpendicular to the traveling direction of the information groove. However, in order to move the light beam, the light deflection means and the focusing optical system must be moved simultaneously. However, these devices are generally heavy and use a mechanism that moves at high speed to speed up the search, resulting in poor positioning accuracy. This error in positioning accuracy is referred to as a blur. There is also a setting error between the disk and the above-mentioned moving mechanism. This is called B Buddha. Furthermore, if the disk is in a rotating state, there will always be eccentricity (misalignment between the center of rotation and the center of the disk). This amount of eccentricity is defined as the amount of eccentricity. Then, the error between the moved light beam and the desired information groove is a+b
It becomes a 10c mountain surface. This amount must be smaller than the field of view of the objective lens for Chikuto. Normally, a will be about 20mm skin, b will be about 20mm skin, and c will be about 20mm skin. It is small enough for the field of view of 500 Buddhas.

Therefore, the desired information groove will never be out of sight.
In order to find the desired information groove from the loose information within the above error, the frequency of the information groove synchronization detection standard signal is changed by △f as described above. The number of information grooves) may be larger than the number of information grooves within the above error. That is, it is sufficient if n×6>a+b+c.

Further, the highest frequency of the synchronization standard signal of the information groove in the block must be lower than the frequency f that does not affect the signal obtained by binary-modulating the information during reproduction.

That is, f>ra(n-1)XAf Must be.

As described above, from the playback conditions, the frequency interval △f
, the total number of information grooves in the block, etc. are determined. Now,
If the light beam that has moved to the vicinity of the desired information groove is pulled in to cancel out the interference with the information groove caused by disturbance, the time it takes for the light beam to cross one information foil becomes longer, and during that time the photoelectronic wave of the reflected light is The converted output signal is demodulated, the synchronization detection standard signal is extracted, and its frequency is measured to detect the deviation between the traversed information groove and the desired information groove.

As a result, the light beam is moved to the desired information groove by the optical deflector, tracking is performed in which the light beam tracks the desired information groove, and the desired information is read out. By the above-described reproduction method, it is possible to find the information groove in which desired information is recorded and reproduce it accurately. In this information recording and reproducing method, in which a synchronization detection standard signal is recorded together with the information signal during recording and used for pull-in and tracking during playback, changing the frequency of the synchronization detection standard signal for each information groove during recording is a key to the pull-in during playback. Needless to say, there are no problems with the tracking operation.

Regarding information grooves that are continuously formed, such as information grooves recorded in a spiral shape on a disk, there are two ways to record by changing the frequency of the synchronization detection standard signal discontinuously or continuously during recording. There is a way. When the frequency of the synchronization detection standard signal mentioned above is changed discontinuously, the principle described for the same 0-circular recording groove formed on the disk holds true. In addition, when the frequency of the synchronization detection standard signal is changed continuously during recording, the correspondence with the information groove is limited to the range of the frequency that changes between unit information grooves, such as during one revolution of the disk. If we decide to take , the principle stated earlier holds true. Next, embodiments of the present invention will be described using the drawings, taking the case of a disk as an example.

First, an information recording apparatus of the present invention using a light beam as a disc irradiation beam will be explained with reference to FIG.
In FIG. 2, an information source 10 such as a VTR, television receiver, etc.
The signal from the source is modulated by the modulator 11 according to the signal source. Further, a synchronization detection standard signal generated from a frequency variable oscillator (for example, a voltage controlled oscillator) 12 is modulated by a modulator 13, and added to the signal from the modulator 11 by an adding means 14, and then Receives binary modulation. This modulated signal 15 is then input to a drive circuit 16 of a light beam intensity modulating means (for example, an EO modulator or an AO modulator) 17 . A light beam 19 generated from a laser light source 18 is modulated by a light beam intensity modulator 17, and is applied to a photosensitive material on a rotating disk 22 by a light deflector 20 such as an AO deflector or an EO deflector and a focusing optical system 21. The information groove is recorded. At this time, the output of the oscillator 12 is input to the drive circuit 23 of the optical deflector 20, and the optical deflector 20 is driven to cause the optical beam to vibrate minutely in the radial direction of the disk. Furthermore, the input relationship of the storage circuit 26 for searching will be explained. As the signal source 10, a television signal is taken as an example. In this case, 1 frame is 1
corresponds to two information channels. In the case of retrieval, there is a method of matching the contents of frames to be stored with information grooves, but this would complicate the configuration, so here we will use another configuration (not described in the embodiments of the present invention) to match the contents of frames to be stored. Let us take as an example the case where the contents of the data and the order in which they are stored are already known. The signal processing circuit 24 extracts a vertical synchronization signal from the television signal.

Two vertical synchronization signals are combined into a television signal as pulse-like signals in one frame. 1 per frame through a circuit such as a flip-flop.
It is configured such that one pulse appears as an output. The measuring device 27 measures the pulse signal 25, which is the output of 24, with a counter, and carries it up when the value reaches n or more. The carried number is sent to the storage circuit 28 in the form of a signal 29.
Similarly, a number not to be carried is sent to 28 in the form of signal 30. In this configuration, signal 29 represents the number of blocks and signal 30 represents the number within the block. In the frequency control circuit 26, the measuring device from the measuring device 27 is converted into an analog voltage by a D/A converter, and the oscillator 1
Enter 2. As a result, the excavation frequency from the oscillator 12 changes for each information groove within the block. This interval is determined by the lowest setting of the D/A converter. In the memory circuit 28, the output 2 from the signal processing circuit 24
5 as a clock, signal 2 corresponds to the recording order.
9 and the contents of signal 30 are stored.

At the same time, the output l from the frequency control circuit is input to the storage circuit. This makes it possible to determine in what block the recorded information groove is recorded and what number in that block it is, and also to find out the correspondence with the frequency of the synchronous search standard signal. 2
5, the drive circuit 31' is activated every time a pulse is received.
The mechanism 32 for moving the focusing optical system is moved by 8 mm in the radial direction of the disk.

This can be achieved using normal mode. Next, a comparison will be made between the recording frequency (of the synchronization detection standard signal) and the frequency of the information source signal.

As an example, an NTSC television signal is recorded as the information source signal. A modulator 11 performs FM modulation on the NTSC signal. The carrier frequency at that time is the mother MHz.
The lower sideband is recorded on the disk.The audio is FM modulated around 2MHz and recorded.At this time, the spectrum (of frequency) of the output of the modulator 11 is shown in Fig. 3. After FM modulating the video signal, the frequency band is
A portion of the lower sideband and upper sideband is extracted.

Reference numeral 42 indicates a double side band in which the audio is FM modulated.

One method is to insert the synchronization detection standard signal into the video signal band 41. According to this method, the frequency interval Δf for each information groove of the synchronization detection standard signal can be increased, but it must still be inserted at a low level so as not to affect the video signal. Specifically, the shaded band 43 in FIG. 3 is used. At this time, the modulator 13 performs FM modulation of the carrier frequency Z. Another method is the fourth
As shown in the figure, this is a method of bringing the band 43 of the synchronization detection standard signal outside the band of the video signal. In this method, the level during recording is high and the synchronization detection standard signal can be reliably detected during reproduction, but Δf cannot be high. This method eliminates the need for the modulator 13 during recording. Now, if you try to put information for 30 minutes of video playback on a disk that rotates at 180 pm, you will need 5,400 information grooves. 30
If all these information grooves are recorded on the 00 disc,
The pitch interval is approximately 2〃.

If we use the formula mentioned in the explanation of the principle, we can roughly divide the block into 0 blocks and reduce the number of information grooves in the block to 10.
You can set it to 0. If the frequency interval is selected to have a one-ship ratio so as not to affect the video signal, the method shown in FIG. 4 causes no problem because the upper limit of the synchronization detection basic signal is 2 MHz or less.
Next, the information reproducing apparatus according to the present invention will be explained using the embodiment shown in FIG.

However, since the device related to the pull-in and tracking mechanism is described in detail in the above-mentioned patent application specification, the operation will be described briefly in this embodiment, and only the part related to the information retrieval device will be described in detail. In FIG. 5, a laser beam 51 is generated from a laser light source 50, passes through a semi-transparent mirror 52, a light deflecting means 53 (preferably a galvano mirror),
A microspot is formed on a rotating disk or disk sheet 55 through a focusing optical system 54 .

Reflected light 56 from the disk 55 passes through a condensing optical system 54, a light deflection means 53 such as a galvano mirror, and a semi-transparent mirror 52, and enters a photoelectric conversion means 57. Next, the photoelectric conversion output signal is input to the demodulator 58, and a synchronization detection standard signal when the microspot crosses the information groove is extracted and input to the frequency measuring means 60. At this time, in order to extract the synchronization detection standard signal, the filter 58 has a filter function that passes only the band indicated by diagonal lines in FIGS. 3 and 4. Signals other than the synchronization detection standard signal pass through a video demodulator 61 and are input to a television receiver 62, where the video is reproduced. When the synchronization detection standard signal is FM modulated as shown in Figure 3,
A demodulator 59 for the synchronization detection standard signal is required, but the fourth
This is not necessary in the signal processing shown in the figure. The photoelectric conversion output signal passes through an AM detector 63, undergoes envelope detection, and is input to a synchronous rectifier 64. At 64, the synchronization detection standard signal which is the output signal from 58 is used to detect the shift between the micro spot and the center of the information groove and its direction.

This becomes a signal for tracking control. Next, the search method and device will be explained.

In the explanation of the present invention, the recording number of the desired information groove is specified from the order specifying circuit 65, which specifies the number of the information groove in the order in which the desired information is recorded.
I did not explain the details of 65, but only the role of 65. Input the output of 65 into the memory circuit used to explain the recording device, and determine which block the desired information belongs to.
The storage circuit 28 inputs to the block designation circuit 66 the number of the information groove from the beginning of the block.

At step 66, a command is given to a drive circuit 68 that drives a mechanism 67 that moves the light deflection means 53 and the condensing optical system 54 together to move the device 67 to the vicinity of the desired information.

69 detects the position of 67 and provides feedback to 66 to accurately position it.

70 converts the frequency of the desired information groove into a voltage, measures the frequency of the synchronization detection standard signal of the information groove that the microspot is currently passing through, and uses the comparator 71 to measure the frequency of the synchronization detection standard signal of the information groove that the microspot is currently passing through. The jump circuit 72 that causes the light beam to jump from one information groove to another is activated by detecting the discrepancy between the current information groove and the desired information groove, and the optical deflection means 53 moves the light spot to the desired information groove. When the light spot reaches the information groove, the comparator 71
Since the output of the synchronous rectifier 64 becomes zero, at this time the output of the synchronous rectifier 64 is input to the optical deflector drive circuit 73 to perform tracking, reproduce the desired information, and output the video to the television receiver 62.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams of the present invention. Poor 1 grade Rokugobako Turtle 4 Ushio 2 evil *Evening ‘○

Claims (1)

[Claims] 1. A rotating recording medium is irradiated with an irradiation beam modulated by an information signal to form a plurality of information grooves along the rotating direction, and a plurality of information grooves are formed on the rotating recording medium. In the information reproducing method of reproducing the information signal by emitting a light beam and converting the reflected light or transmitted light into an electric signal, the plurality of information grooves are divided into blocks for each of the plurality of adjacent information grooves,
and is formed by superimposing a standard signal of a different frequency on the information signal for each information groove in each block, and
The light beam is positioned near the desired information groove using a signal indicating the block address to which the desired information groove belongs, and the standard signal detected from the electrical signal is compared with the standard signal corresponding to the desired information groove. and thereby positioning the light beam in the desired information groove and reproducing the information signal recorded in the desired information groove. 2. In a recording medium in which a plurality of information grooves formed by information signals are formed along the rotation direction, the plurality of information grooves are divided into blocks for each of a plurality of adjacent information grooves, and within each block, A recording medium characterized in that a standard signal of a different frequency is recorded for each information groove in a manner superimposed on the information signal. 3. A plurality of information grooves formed by an information signal are divided into blocks into a plurality of adjacent information grooves, and within each block, a standard signal of a different frequency is superimposed on the information signal and recorded for each information groove. an irradiation means for irradiating a light beam onto a recording medium formed by the recording medium; a photoelectric conversion means for converting reflected light or transmitted light from the recording medium into an electrical signal; and recording in the information groove from the output signal of the photoelectric conversion means. a signal generating means for generating a signal indicating a block address to which a desired information groove belongs and a standard signal corresponding to the desired information groove; a first position control means for controlling the relative position of the light beam and the desired information groove by a signal indicating the standard signal from the demodulation means and the desired information groove from the signal generation means; and a second position control means for controlling the relative position of the light beam and the desired information groove based on the output signal of the comparison means. Information reproducing device.