JPH0442732B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an information recording device that records information such as video, audio signals, computer data, etc. on a recording medium at high density so that desired information can be accurately read out. The present invention relates to a recording method and apparatus.

[Background of the invention]

Conventionally, information such as video signals and computer data is modulated into binary form, and recorded on a recording medium, for example, in a non-contact, high-density, uneven or light and shaded form, on a disk, and then used as an irradiation beam such as a light beam. 2. Description of the Related Art An information retrieval device is known that uses a contactless method to accurately reproduce desired information. Such an information retrieval device detects the information groove in which the necessary information is recorded from among the information recorded in high density, moves the irradiation beam to the above-mentioned position, and retrieves only the necessary information. must be accurately extracted and played.

As a solution to this problem, when playing back a disc in which the information grooves on which information is recorded are concentrically formed on the disc, conventionally, as detailed in Japanese Patent Application Laid-Open No. 49-68614, the TV image is A signal indicating the order of the information grooves is inserted into a portion of one information groove corresponding to one frame (within the vertical retrace period), and a light beam is moved to the vicinity of the desired information groove during playback.
The order of the information grooves is determined by positioning a light beam in one of the information grooves near the desired information groove, then tracking the information groove, and reproducing the information recorded in the information groove. This method detects a signal indicating the desired information, detects the deviation from the desired information groove, and moves the light beam to the information groove in which the desired information is recorded. However, in order to push out the desired information groove, this method requires tracing an information groove different from the desired information groove at least once, and detecting a signal indicating the order. Therefore, there is a problem in that it takes a very long time to reproduce information from a desired information groove.

[Purpose of the invention]

An object of the present invention is to provide an information recording method and apparatus that can solve the above-mentioned problems when searching for desired information.

[Summary of the invention]

In order to achieve such an object, in the present invention, when forming a plurality of information grooves by irradiating an irradiation beam modulated by an information signal, the plurality of information grooves are divided into blocks for each of a plurality of adjacent information grooves. , a standard signal of a different frequency is formed for each information groove in each block by superimposing it on the information signal.

In order to explain the outline of the present invention, in this specification, regarding the tracking method, reference will be made to Patent Application No. 12968/1988, "Information Recording/Reproducing Method and Apparatus" previously filed by the present inventors. (Tokuko Showa 54-
15727), but there is no problem in implementing the present invention with other tracking methods as will be described later. Further, the retraction is explained in Japanese Patent Application No. 50-9721, ``Automatic Retraction Method'' (see Japanese Patent Publication No. 16325-1981), which was previously filed by the present inventors. Therefore, the information retrieval method and apparatus will be mainly explained here.

[Embodiments of the invention]

In order to search for a desired information groove from a medium in 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 focusing objective lens (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, distinguish the desired information groove 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 positioning 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 a head of about 600 g is used, the positioning accuracy will be about 20 μm.
Since the field of view of the objective lens is usually about 500 μm,
The first requirement can be satisfied. Regarding the second method, the frequency of minute vibrations 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, and the frequency is Distinguish information grooves by detecting them. Next, the content of the present invention will be described in more detail.

In order to accurately perform tracking, pull-in, and information groove searching 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, pulse width modulation, pulse position modulation, etc. Modulation that has meaning as phase information (hereinafter referred to as binary modulation)
The intensity of a light beam, an electron beam, etc. (hereinafter collectively referred to as an irradiation beam) for processing a recording medium is modulated using the modulated signal.
Next, the intensity-modulated irradiation beam is minutely vibrated in a direction perpendicular to the traveling direction of the information groove to be created using a signal having the same frequency and phase as the standard signal for synchronization detection, and the recording is moved. Irradiate onto the medium. Preferably, the amplitude of the minute vibration is less than half the sum of the width of the recorded information groove and the width of the reproduction spot, in order to reduce crosstalk in the reproduced image.

In such a situation, in the present invention,
An information groove is created by changing the frequency of the standard signal for synchronization detection continuously or discontinuously. 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 up a disk as a recording medium, a case will be described in which the above-mentioned synchronization detection standard signal is changed discontinuously. First, according to the order in which all the unit information grooves to be recorded are recorded, an appropriate number (assuming n) of unit information grooves are grouped together as one block, and all recorded information grooves are divided into N blocks. Separate. 1
In one block, the position of the irradiation beam is changed by 1 in the radial direction of the disk during one rotation of the disk.
The above recording is performed by stopping at a point and 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 pitch intervals σ μm, the frequency of the synchronization detection standard signal is changed at frequency intervals Δ every time the irradiation position of the light beam in the disk radial direction changes, that is, for each unit information groove. Then record as described above. As a result, the disk on which information is recorded becomes as shown in FIG. The information grooves on Daytech 1 are concentric circles with a pitch interval of σμm. Although not shown in the figure, n information grooves are lined up from the first information groove 3 to the last information groove 4 of a certain block. If the frequency of the synchronization detection standard signal of the first information groove 3 (the frequency of minute vibration in the direction perpendicular to the direction of movement of the information groove) is _p , the frequency of the synchronization detection standard signal of the last information groove 4 is _p + (n −1)×Δ.
For each block composed of n information grooves, 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, it can be seen that a particular information groove on the disk corresponds to a frequency of a particular synchronization detection standard signal in a particular 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 at the same time 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 becomes a spiral on the disk, and by detecting the synchronization detection standard signal recorded in the information groove, the information groove being reproduced can be determined from the beginning of the block. It can be seen that this is the third information channel.

Next, we will describe the principle of finding the 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 above method and reproducing it accurately. First, the information groove in which the desired information is recorded belongs to a certain block, and the number from the beginning of the block is specified. To do this, the unit information groove in which specific information is recorded, the block number, and the number within the block are stored in advance in a recording device, etc., and 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 together. 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. The error in this positioning accuracy is assumed to be aμm. There is also a setting error between the disk and the above-mentioned moving mechanism. this
bμm. Furthermore, if the disk is in a rotating state, there will always be eccentricity (deviation between the center of rotation and the center of the disk). Let this amount of eccentricity be cμm. Then, the error between the moved light beam and the desired information groove is (a+b+c) μm. This amount must be smaller than the field of view of the focusing objective. Normally, a is 20μm, b is 20μm, and c is also 20μm.
It will be about m. It is sufficiently small for a field of view of 500 μm. Therefore, the desired information channel will never be out of sight. In order to find a desired information groove from among the information grooves within the above error, the frequency of the standard signal for synchronization detection of the information grooves is changed by Δ as described above. The number of information grooves) may be larger than the number of information grooves within the above error. That is, n×σa+b+c is sufficient.

Furthermore, the highest frequency of the standard signal for detecting the synchronization of the information groove within the block must be lower than a frequency that does not affect the signal obtained by binary modulating the information during reproduction. That is, it must be > ₀ + (n-1) x Δ.
As described above, the frequency interval Δ, the total number of information grooves in a block, etc. are determined from the reproduction conditions.

Now, if the light beam that has moved to the vicinity of the desired information groove is pulled in to cancel out the blurring with the information groove caused by disturbance, the time that the light beam crosses one information groove becomes longer, and during that time the reflected light The photoelectric conversion 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 using 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,
The frequency of the synchronization detection standard signal is made discontinuous during recording.
Alternatively, there are two methods of continuously changing and recording. When the frequency of the above synchronization detection standard signal is changed discontinuously, the principle described for concentric recording grooves formed on a disk holds true. In addition, if the frequency of the synchronization detection standard signal is changed continuously during recording, the information groove will have a width only within 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 following action, the principle stated earlier will hold 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 disk irradiation beam will be explained based on FIG.

In FIG. 2, a signal from an information source 10 such as a VTR or television receiver is modulated by a modulator 11 in accordance with the signal source. Further, the synchronization detection standard signal generated from a frequency variable oscillator (for example, a voltage controlled oscillator) 12 is modulated by a modulator 13, and after being added to the signal from the modulator 11 by an adding means 14, It undergoes the binary modulation mentioned earlier. This modulated signal 15 is then transmitted to a light beam intensity modulating means (e.g. an EO modulator or
input to the drive circuit 16 of the 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 directed onto a rotating disk 22 by a light deflector 20 such as an AO deflector or an EO deflector and a condensing optical system 21. The light is focused on the photosensitive material, and an 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 to drive the optical deflector 20 to cause the optical beam to vibrate minutely in the radial direction of the disk. Furthermore, the input relationship of the control circuit 26 for searching will be explained. As the signal source 10, a television signal is taken as an example.

In this case, one frame corresponds to one information groove. In the case of retrieval, there is a method of matching the content of the frame to be recorded with the information groove, but since the configuration is complicated, here we will use another configuration (not described in the embodiments of the present invention) to perform storage. For example, let us consider a case where the contents of the frames to be recorded and the order in which they will be recorded 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. Through a circuit such as a flip-flop, one pulse per frame is arranged to appear as an output. The measuring device 27 measures the pulse signal 25, which is the output of the pulse signal 24, with a counter, and performs a carry when the number of information grooves allowed in one block reaches a value of n or more. The carried number, ie, the block number, is sent to the memory 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, 29 signals represent the number of blocks, and 30 signals represent the signals within a block.
This is the signal. In the frequency control circuit 26, the measuring device 2
The measured value from 7 is converted into an analog voltage by a D/A converter and input to the oscillator 12. As a result, the oscillation 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.

The storage circuit 28 uses the output 25 from the signal processing circuit 24 as a clock to store the contents of the signals 29 and 30 in the order in which they were recorded. At the same time, the output from the frequency control circuit is input to the storage circuit. This makes it possible to determine in what block the recording information groove is recorded and in what block it is located, and also to determine the correspondence with the frequency of the synchronization detection standard number.

25, the drive circuit 31 moves the mechanism 32 that moves the condensing optical system to σμ every time a pulse is input.
m in the radial direction of the disk. This can be achieved with a normal motor.

Next, a comparison will be made between the recording frequency (of the synchronization detection standard symbol) 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. Select the carrier frequency at that time to be around 8MHz, and record the lower side wave band on the disk. Audio is FM modulated around 2MHz and recorded. The spectrum (of frequency) of the output of the modulator 11 at this time is shown in FIG. The 41 frequency band is obtained by extracting a portion of the lower sideband and upper sideband after FM modulating the video signal. 42 indicates both measurement bands 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 Δ 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 has a carrier frequency of 4MHz.
Performs FM modulation. Another method is to provide a synchronization detection standard signal band 43' outside the video signal band, as shown in FIG. With this method, the level during recording is high and the synchronization detection standard symbol can be reliably detected during playback, but Δ cannot be high. This method eliminates the need for the modulator 13 during recording. Now, if I try to input information for 30 minutes of video playback onto a disk that rotates at 1800 rpm,
54,000 information grooves are required. If all of this information is recorded on a 300φ disk, the pitch interval will be approximately 2 μm. Using the formula described in the explanation of the principle, it is sufficient to divide the block into 540 blocks and set the number of information grooves in the block to 100.
Frequency spacing so as not to affect the video signal
If 16kHz is selected, the method shown in Figure 4 will cause no problem since the upper limit of the synchronization detection standard signal will be 2MHz 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 only be briefly described 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, passes through a light deflection means 53 (preferably a galvanometer mirror), and a condensing optical system 54, and then passes through a rotating disk or disk. - Form microspots on the sheet 55. 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, a synchronization detection standard signal when the microspot crosses the information groove is extracted, and the frequency measurement means 60
Enter. 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 FIG. 3, a demodulator 59 for the synchronization detection standard signal is required, but in signal processing as shown in FIG. 4, it is not necessary. The photoelectric conversion output signal is
The 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 deviation 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.
The recording number of the desired information groove is designated from an order designation circuit 65 which designates the number of the information groove in the recording order in which the desired information content is located. In the description of the present invention, the contents of 65 were not described in detail, but only the role of 65 was described. The output of 65 is input to the memory circuit 28 used to explain the recording device, and the memory circuit 28 specifies the block to which the desired information belongs and the information groove from the beginning of the block. input to circuit 66; At 66, a drive circuit 68 drives a mechanism 67 that moves the light deflection means 53 and the condensing optical system 54 together.
67 is moved to the vicinity of the desired information. 69 detects the position of 67 and provides feedback to 66 for accurate positioning. 70 converts the frequency of the desired information groove into a voltage, and converts the frequency of the synchronization detection standard signal of the information groove that the micro spot is currently passing through to 6.
0, a comparator 71 detects the deviation between the information groove passing through and the desired information groove, and operates a jump circuit 72 that jumps the light beam for each information groove, and deflects the light. The light spot is moved to the desired information groove by means 53, and only when the light spot reaches the desired information groove,
Since the output of the comparator 71 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 image to the television receiver 62. .

〔Effect of the invention〕

As described above, according to the present invention, the recorded information grooves are divided into blocks and the information grooves are ordered in each block, so that the desired order of the information grooves can be read, and thereby the desired information can be read. This makes it possible to significantly shorten the search time required to find the information, and has a significant effect on speeding up information retrieval.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams of the present invention.

Claims (1)

[Scope of Claims] 1. An information recording method in which 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 of the recording medium, wherein the plurality of information grooves are An information record characterized in that the information is divided into blocks for each of a plurality of adjacent information grooves, and within each block, a standard signal of a different frequency is superimposed on the information signal so as to be repeated for each block. Method. 2. A rotating recording medium, an irradiation means for irradiating an irradiation beam onto the recording medium, a control means for controlling the relative position of the irradiation beam and the recording medium, and a pulse for each unit of information of an information signal to be recorded. a counting means that counts the pulses and carries them up when they exceed a predetermined value, stores the carried value in a storage device, and outputs the remaining count value; A signal generating means for generating a standard signal having a different frequency in accordance with a count value, and a modulating means for modulating the irradiation beam by a signal obtained by superimposing an output signal of the signal generating means on the information signal. An information recording device characterized by: