JPS6142339B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disk technology based on a new tracking principle.

Conventionally, there have been two types of electrostatic disk technology in which information such as images or audio is recorded in the form of a spiral pit row on a conductive disk and this is detected as a change in capacitance. One type is similar to conventional audio records, in which a continuous groove is formed along with a spiral pit row, and the thin stylus of the pickup automatically follows this groove. This format has the advantage of not requiring a tracking servo because tracking is performed automatically using the pressure of the needle, but it has the disadvantage that still playback is not possible when applied to video discs.
Furthermore, when recording, it had the advantage that it was possible to use optical beam recording, electron beam recording, and mechanical recording. For details, see RCA Review Vol 39,
It is written in No.1.

Another type is a method in which no groove is formed, and a tracking pilot signal is inserted between adjacent pit rows for tracking. The advantages of this method, when applied to video discs, are that still playback is possible and that the stylus pressure can be relatively light (approximately 40 mg), extending the life of the stylus and disc. But on the other hand,
As a natural compensation, in addition to the need for a tracking servo system on the playback player side, when recording, a total of two light beams are required: a main light beam for recording the main signal and a pilot light beam for recording the pilot signal. The disadvantage was that it required The pilot beam was separated and combined from the main beam using a semi-reflecting mirror, but in order to increase the recording density, the distance between the main beam and the pilot beam was set to about 0.7 μm on the disk. A high precision of ±0.1 μm is required, and maintaining this precision during recording is extremely difficult due to the precision of mounting the semi-reflector. Moreover, slight variations in temperature, vibration, changes over time, etc. tend to cause discrepancies, which reduces the yield of recording and is considered an industrial problem. Furthermore, since it was necessary to use a photoresist film process during recording, there was a problem in that defects were likely to occur on the disk due to the incorporation of dust and dirt.

SUMMARY OF THE INVENTION An object of the present invention is to provide a technique that can overcome the drawback of the prior art that two light beams are required for high-density recording on a non-grooved disk.

To achieve the above object, the present invention does not record the pilot signal between adjacent main signal pit rows, but instead inserts the pilot signal into the main signal pit row itself. Therefore, it is possible to record with one beam or one cutting head without providing an extra pilot beam. In other words, when recording the pilot signal, it is possible to simply add the pilot signal to the main signal purely electrically.
The key point is how to configure the pilot signal. More specifically, the key point is that the pilot signal is given one of three or more mutually distinguishable features for each round of the track on the disk.

A basic embodiment of the present invention will be described below. The present invention will be explained using an example of a video disk in which four fields of image signals are recorded per revolution of the disk.

FIG. 1 shows the recording signal formation process. 1 in the same figure
is a main information signal such as an image, 2 is an FM modulator, and 3 is an unnecessary wave rejection filter, which removes unnecessary waves from the input high-frequency FM signal (usually, the main energy is distributed over 4MHz). The removal frequency band is selected so as to remove at least unnecessary waves in the low frequency band occupied by the pilot signal described below. 4 is an FM signal. 5, 6, and 7 are 0th, 1st, and 2nd pilot signals for tracking, and their frequencies are assigned different frequencies ₀ , ₁ , and _2, respectively, in the lower region of the high frequency FM signal frequency band. . A suitable example is ₀ ≒ 600KHz,
₁ ≒ 800KHz, ₂ = 1MHz. A switching pulse 8 is generated at a rate of one per rotation of the disk, and is obtained by detecting the rotational phase of the disk of the recorder, or by dividing the frequency of the synchronization signal in the main information signal. Specifically, the vertical field synchronization signal is
It can be obtained by dividing the frequency by 4, and in the case of application to the NTSC system, it becomes a pulse signal with a fundamental frequency of 15Hz, and in the case of application to the PAL and SECAM systems,
It becomes a 12.5Hz pulse signal.

The parallel/serial switch 9 is for sequentially outputting one of the three pilot signals for each disk rotation period, and the switching timing is as follows.
This is the rising edge of the input switching pulse 8. The specific configuration of the switch is not the main point of the present invention, and various well-known techniques can be used. For example, a commercially available semiconductor analog switch IC (CD4066 manufactured by RCA) can be used. The frequency of the output signal of this switch is ₀ , ₁ , ₂ , ₀ , ₁ ,
₂ ,... are arranged in chronological order. 10 is a timing pilot signal, which has a low frequency ₃ different from the above-mentioned ₀ , ₁ , and ₂ (as a suitable example, ₃ ≒
The frequency shall be 200KHz. ). This timing pilot signal is gated by a gate circuit 11 so as to pass only the high potential period of the switching pulse 8, and is then applied to an adder 12. The gate period is selected within the vertical retrace period of the image. Adder 1
A composite pilot signal 14 is obtained at the output of 2, which is added together with the FM signal 4 in an adder 13 to obtain a composite FM output signal 15. Second
Figures a to c show the waveforms of the main parts of Figure 1.
This is the waveform of the signal with the same number as in the figure. In the figure, 4 is a high frequency FM signal, and 14 is a low frequency composite pilot signal. 15 indicates the added composite FM output signal. This output signal is applied to a recorder which modulates the intensity of the recording light beam or electron beam or the displacement of the cutter head, using known techniques, and is recorded as a spiral pit array on the master disk. FIG. 3 is an enlarged view of a part of the pattern of this pit row. The figure shows 3N tracks to 3N+2 tracks (N
are natural numbers), respectively in Figure 4 a~
This corresponds to the pilot waveform shown in c. The 3rd N track has the 0th pilot frequency.
₀ indicates that the first pilot frequency ₁ is recorded on the 3N+1 track, the second pilot frequency ₂ is recorded on the 3N+2 track, and so on. Note that in the above description of pit rows and waveforms, the timing pilot signal has been omitted. As described above, since only one portion is recorded per one rotation period of the disk, the disk appears to be recorded on one radius.

This concludes the explanation of the recording process, and next we will describe how tracking discrimination is made possible in the reproduction process.

FIG. 5 shows a block diagram of the regeneration process. In the figure, 31 is a disk, which is not shown in the figure, but is rotated by a motor at a speed of 15 Hz or 12.5 Hz. 32 is an electrostatic detection type pick-up with a tracking servo actuator;
The width of the conductor at the tip of the regenerating needle is selected to be approximately the same as the track width in FIG. 3 (approximately 1 to 2 μm). 33 is the composition detected from the pick-up
It is an FM signal. 43 is the above synthesis using an FM filter
Removes low frequency pilot signals in FM signals.
44 is an FM demodulator, and 45 is an output main information signal. Reference numerals 34 and 35 in FIG. 6 are after-past and past-past discriminators, which will be described below, and 36 and 37 are past-past and past-past signals, respectively, which are discrimination outputs. Reference numeral 38 denotes a subtracter, and its output 39 provides a servo signal for determining the past and the past. This servo signal 39 is returned to the tracking actuator of the pickup 32 described above and is subjected to negative feedback control using well-known techniques. 40 in the same figure is a filter for detecting timing pilot signal frequency ₃ , and its output is as follows.
By the switching pulse 8 already described in FIG. 1, a waveform whose envelope is amplitude-modulated is obtained. Reference numeral 41 denotes a timing pulse generator, and by envelope-detecting its input, a timing pulse 42 is obtained as its output. Note that the operation control section 61 is for special reproduction such as still reproduction, and will be described later.

Next, FIG. 6 shows the configuration of the past signal discriminator 34. In this figure, parts with the same numbers as in FIG. 5 represent the same contents. The composite FM signal 33 is connected to the resistor 4
6, the current is converted into a current source, and applied to a switched control filter consisting of an inductor 47 and capacitors 48, 49, and 50, and then envelope-detected by a diode to become a post-current signal. The capacitor 48 and the inductor 47 constitute a parallel resonant circuit tuned to the 0th pilot frequency ₀ . Similarly, capacitors 49 and 50, along with inductor 47, each
Construct a parallel resonant circuit tuned to ₁ and ₂ . The Q of each filter should be high enough, and the i filter should be
The configuration is such that it can sufficiently suppress other pilot signals. Each series resistor of each capacitor is used to match the tuning impedance level of each parallel resonant circuit and absorb the gain difference. 51 is a changeover switch, and the timing pulse 42
This is to switch the tuning frequency of the filter in an orderly manner every time the rising edge of . The configuration of the forward signal discriminator 35 in FIG. 5 is basically as follows.
This is the same as shown in FIG. However, after the
It is necessary to maintain the linkage of each switch by considering the previous order relationship. For this purpose, the capacitors constituting the filter in the past discriminator are not shown, but are called 48', 49', and 50', and their corresponding tuning frequencies are selected as ₂ , ₀ , and _1, respectively. I'll keep it. If you do this, the switch can be used for
The capacitors for both ends are 48 (48') and 49 (4
9'), 50 (50'), 48 (48'), 49 (4
9'), 50 (50'), and so on. First of all, pick up is the first step.
If you are playing 3N+1 tracks, the 3rd
As can be seen from the figure, pilot frequency ₁ is recorded in the own track, ₀ is recorded in the next adjacent track, _{and 2} is recorded in the next adjacent track. Therefore, the capacitor is 48 (4
All you have to do is activate the combination 8')). When the disk further rotates and a timing pulse is detected, as can be seen from FIG.
3N+2, 3N+3, and the pilot frequencies become ₁ , ₂ , ₀ accordingly. Therefore, the capacitor 49 (49') may be activated. The same applies below.

Therefore, appropriate past and past information can always be obtained from the outputs of the discriminators 34 and 35 shown in FIG.
When the pick-up stylus tip is just scanning the middle of the desired track, both of the above-mentioned past and past signals are hardly detected, so the subtracter output servo signal in Fig. 5 is balanced. . On the other hand, when the stylus tip lags behind the desired track and is biased toward the outer circumference of the disk, past information is generated as a servo signal approximately in proportion to the amount of deviation. On the other hand, when the needle tip advances too far from the desired track and is biased toward the inner circumference of the disk, overshoot information with a polarity opposite to that of the previous example is generated as a servo signal in approximately proportion to the amount of deviation. Thus, a suitable servo signal 39 is always continuously available at the output of the subtracter 38, so that correct tracking is achieved by well-known servo techniques. The relationship between the track residual deviation amount and the detected servo signal, that is, the discrimination logic characteristic, is shown by the dotted line in FIG. In the figure, the horizontal axis shows the track deviation amount using the desired track as a reference number difference, and the vertical axis shows the detected servo signal. As can be seen from the figure, when the track deviation is within the range of ±1 track, a substantially proportional detection signal is obtained, and macroscopically, it becomes a triangular wave-like periodic function every three track periods.

In conventional tracking methods, when a track deviation occurs on a grooved disc, even instantaneously by 0.5 tracks or more, the track immediately jumps to another track, which may break the continuity of information reproduction. In contrast, in the present invention,
Even if a track deviation of up to ±1.5 tracks occurs, the servo can be expected to provide restoring force, making it possible to continuously and stably reproduce information. In addition to this, a particularly noteworthy feature of the present invention in its application to video discs lies in the ease with which the special playback function for stills and the like described below can be achieved.

First, in still reproduction, it is sufficient to simply stop the generation of the output timing pulse 42 from the pulse generator 41 in response to an instruction from the operation control section 61 shown in FIG. Of course, although not shown in the figure, the operation of the pick-up feed system is also stopped.
In this way, even if the timing pilot signal is detected as the disk rotates, the discrimination logic of the discriminators 34 and 35 is not changed and is maintained as it was.
Then, as is clear from the discriminant logic characteristic of FIG. 7, it becomes impossible to continue scanning successively the next numbered track along the spiral track. On the contrary, a restoring servo force with clear polarity works to return to the original track, and therefore still reproduction is easily achieved. Although not detailed in the conventional explanation, even in the conventional technology using a grooveless disk, in order to achieve still reproduction, at least a pulse acting in the direction of electrical restoration polarity is applied to the tracking actuator. This required extra effort.

According to the present invention, this can be eliminated, and the still playback function can therefore be achieved more stably.

Next, in slow motion playback, for example,
In the case of 1/4 speed, in Fig. 5, the timing pulse generation is not completely stopped, but every four timing pilot signals are detected.
It suffices to generate timing pulses.

For this purpose, the pulse generator 41 must be supplied with 1/4
This can be easily achieved by providing a frequency dividing function and activating it according to instructions from the operation control section 61. In general, 1/M speed slow motion playback, where M is an integer, can be achieved as well. For quadruple speed reproduction, conversely, the frequency of the timing pulse may be increased four times and applied to the discriminators 34 and 35. To achieve quadruple rotation, the well-known Phase Locked Loop technique may be used, or vertical synchronization may be used, focusing on the fact that one disk rotation period is equivalent to four image fields in this example. Discriminator 3 uses the signal instead of the timing pulse
It may be added to 4.35. The vertical synchronization signal can be generated from the output main information signal 45 of FIG. 5 by a synchronization separation circuit, not shown, which is well known in the TV art.

Another alternative method for achieving quadruple speed playback without using a frequency doubling circuit using PLL technology will be described below.

In FIG. 5, the waveform of the timing pulse during normal speed reproduction is set to a waveform 71 with a four-field cycle as shown in FIG. 8a. Waveform 7 in figure b
2 is the already mentioned quadruple frequency pulse waveform. A waveform 73 in c of the figure is an alternative waveform. The alternative waveform 73 achieves quadruple speed playback by generating four pulses together within one vertical retrace period and jumping to the forward track three times compared to the normal speed. This means that it is shown in FIG. 9 in a simulated manner on a disk. The figure is for easy understanding.
The tracks are drawn with wider spacing. The spiral of thin lines shows the track of the normal route, and the thick line shows the 4x speed alternative. Note that the dotted line corresponds to the timing pilot signal recording section. Incidentally, the interval between the three subsequent pulses in the group of four pulses is selected to be approximately 60 μsec or more. This is because if the speed is lower than this, the tracking speed limit of the tracking servo system will normally be exceeded. On the other hand, if the interval is too long, the vertical retrace period of approximately 1 msec will be exceeded, and a track jump will occur during the image signal transmission period, which is not a good idea, as it will generate noise bars on the playback screen. This concludes the explanation of forward motion playback, and next, reverse motion playback will be described.

In order to perform reverse motion reproduction, it is sufficient to perform a track jump in the opposite direction starting from the still state. To do this, the discriminator 3 in Fig.
It is sufficient to apply two closely spaced timing pulses to 4 and 35. The interval between both pulses is selected to be sufficiently shorter than the following speed limit of the tracking servo system. Then, the resulting effect of both pulses is to servo the needle so that instead of advancing it two tracks forward, it is pulled backward by one track. This is clear from the fact that the track discrimination logic characteristic described above in FIG. 7 has periodicity every three tracks. Of course, instead of adding two close pulses, it is also possible, although the construction is slightly more complex, to construct the changeover switch of FIG. 6 so that it can be switched according to the opposite permutation.

It is clear that by combining the basic techniques described above, a wide range of double-speed and low-speed playback becomes possible in both forward and reverse directions, depending on the application. Further, in a still state, it is easy to reproduce a frame-by-frame image by sporadically generating switching pulses by manual operation.

In the above description, explanation of the feed speed of the pick-up feed system has been omitted, but of course this feed speed also needs to be changed in conjunction with instructions from the operation control section 61 in FIG. As a means for this purpose, a DC motor capable of continuous speed control in both forward and reverse directions is adopted as the pick-up feed motor, and
It is advantageous to control the motor by the servo signal 39 of FIG. With this configuration, a variety of special playback modes, including during still playback, can be realized extremely simply by the continuous pick-up feed servo.

It should be noted that the present invention can also be applied to random access functions well known in conventional video disc technology. As is well known, in a disk for random access applications, a sequence number in a binary code is superimposed on the image signal at a predetermined position during the vertical retrace period of each track. In some cases, this binary code is similar to the pilot signal described in this example.
It may also be recorded in the low frequency range. In any case, although this binary code signal has been deleted from the explanation in Figure 5, it is extracted in the playback system based on timing information based on the vertical synchronization signal, and is used for disk playback position display and access servo. It is well known that this is the case. During the access servo, the timing pulse generator 41 shown in FIG. 5 of the present invention is killed, that is, in the still playback state, and the pick-up is performed based on the result of the subsequent comparison between the target access number and the playback track number. is forcibly sent. In addition, as previously mentioned, the discriminators 34 and 35 in FIG.
The discriminant logic characteristic of is set to a logical state in which a track having a number equal to the target track number or the remainder of this divided by 3 is held.

This arithmetic processing can also be accomplished by a combination of some logic circuits.

The basic embodiment of the present invention has been described above.

Next, a modification of the present invention will be described.

(1) In the basic example, the zeroth to second pilot signals have been explained as temporally continuous signals. However, in actual application, crosstalk between the image signal and the pilot signal may occur due to nonlinearity included in the recording and reproducing system. As a means to avoid this, it is effective to insert the 0th to 2nd pilot signals only within the image flyback period. For this purpose, a gate circuit using a horizontal or composite synchronization signal may be added between the output of the switch 9 and the adder 12 in FIG. That is, the pilot signal is recorded only during the synchronization signal period. In this way, crosstalk can be avoided and a good image signal with less beat interference can be always reproduced.

Correspondingly, on the playback side, by adding a gate circuit using a synchronizing signal to the input section of the discriminators 34 and 35 shown in Fig. 5, crosstalk from the image signal to the pilot signal is avoided and good tracking is achieved. Can detect servo signals. The synchronization signal for the gate can be easily extracted from the reproduced main information signal 45 using a well-known synchronization separation circuit technique. Although the addition of this gate circuit is not a mandatory requirement for tracking purposes, it is an effective aid.

In business applications, if it is necessary to suppress the crosstalk of the main information signal from adjacent tracks to a particularly low level, the width of the information pit is made smaller in Figure 3, and a guard band is created between adjacent tracks. It is effective to provide However, this makes it difficult to detect pilot signals from both adjacent tracks for tracking on the playback side. As a means to improve this, it is effective to widen the width of the recording pit only during the zeroth to second pilot signal recording periods, ie, the synchronizing signal period. As a means for this purpose, during laser beam recording or electron beam recording, it is effective to increase the average density of the beam only during the synchronization signal period.
In this way, both the width and length of the recording pit can be increased, and the initial purpose can be achieved. When using a cutting head, it is sufficient to cut deeper than usual only during the synchronization signal period. Specifically, there is no need to change the conventional recording machine itself; just add a pulse of positive polarity bias to the output of the switch 9 shown in FIG. Good.
This pulse amplitude is equal to the pilot signal amplitude O-
Setting it to about the P value will have a great effect.

(2) In the configuration of the basic embodiment, it has been stated that a timing pilot signal is used, but this is not an unavoidable requirement. A method for eliminating the timing pilot signal will be described next.

First, during recording, as shown in FIG. 1, a pulse obtained by dividing the vertical synchronizing signal of the image by 1/4 is used as the switching pulse. However, the timing pilot signal is not recorded. Next, on the reproduction side, the timing pilot filter 40 in FIG. 5 is unnecessary. Instead, the vertical synchronization signal is separated from the main information signal 45 and passed through a 1/4 frequency divider circuit with a reset terminal (not shown in the figure) to obtain a timing pulse. As is well known, the output of the 1/4 frequency divider circuit is a quadrivalent multivalued function, so the probability that the output matches the recording timing is
It is 1/4. However, if it is possible to detect an abnormality when the playback operation is performed at the wrong timing, then the
You can reset the 1/4 frequency divider to correct the timing. Abnormality detection is possible from the following.

When a timing pulse is generated at the wrong timing, a pulse with an abnormal amplitude will occur in the servo signal 39 in Fig. 5 during the response time width of the tracking servo system immediately after the timing pulse is generated, resulting in unintended tracking. Do a jump. By detecting this abnormal pulse and resetting the 1/4 frequency divider, it is possible to restore the correct timing. Therefore, the insertion of the timing pilot signal is not an indispensable requirement for constructing the present invention, but is one means for stabilizing the reproduction operation.

Another means of eliminating the need for a timing pilot signal is to use the pilot signal of the desired track itself. As mentioned in Figure 3, in order from the outer periphery of the disk,
The frequency of the pilot signal for each track is
₀ , ₁ , ₂ , ₀ , ₁ , ₂ , ₀ ,
It is recorded as ₁ , ₂ ,... Therefore, on the reproduction side, among the reproduced pilot signals, the frequency of the one with the maximum amplitude is judged by one of the three, and if the result is ₁ , it corresponds to the previous information after passing through ₀ and ₂ , respectively, If the result is ₂ ,
After passing ₁ and ₀ , respectively, it corresponds to the past information, and if the result is ₀ , after passing ₂ and _1, respectively, it corresponds to the past information, and the switching control of the discriminators 34 and 35 in FIG. 5 is performed. Just do it.

(3) In the basic embodiment, the 0th
- It was stated that a total of three pilot signals are used. Alternatively, it is also possible to use more than four pilot signals. However, in this case, the configuration of the reproducing system discriminator becomes complicated.

(4) Although the configuration of the discriminator has been described with reference to FIG. 6, other specific configurations are also possible as means for embodying the present invention. For example, in Figure 6, instead of switching the filter characteristics themselves, the filter
It is also possible to configure the filters as fixed filters, perform envelope detection on each to obtain three outputs, and select two predetermined filters from these three outputs as the past and past information using a switch. . This will be clear from the above explanation regarding the recording order of the zeroth to second pilot signals.

(5) In the explanation of the basic embodiment, the main information signal is
He said that it is FM modulated and its main energy exists in a frequency band of approximately 4MHz or higher. However, in some cases, audio FM signals and other information signals may be recorded in a frequency band of 4 MHz or less, superimposed thereon. In this case, the pilot signal frequency of the present invention is inserted between gaps in the frequency band occupied by the information signal.

(6) Although the basic embodiment has been described as being applied to a video disc, it can also be applied to an audio PCM disc as is. In the PCM technology, a synchronization signal for sampling period discrimination is used as a signal corresponding to the horizontal synchronization signal of an image, so it can be used as a substitute for the synchronization signal used in the description of the basic embodiment. It can also be applied to other methods of converting any information signal into a relatively high frequency and recording it on a disk.

(7) Although the basic embodiment has been explained based on the assumption of an electrostatic detection type disk, it can also be applied to other recording/reproducing systems based on a tracking servo, such as a photoelectric detection type disk, a magnetic disk, a VTR, etc.

When the track structure is applied to a disk,
It does not have to be spiral, but may be concentric. Alternatively, as in a magnetic tape, they may be in the form of mutually adjacent line segments.

(8) This proposal is based on the assumption of a grooveless disk.
However, when the present invention is applied to a mechanical cut method, grooves along the recording pit array are usually generated naturally. However, if the depth of the gap is shallow, it will not be a hindrance to the implementation of the proposal. When applied to a still playback mode, a grooved disk has the disadvantage that the stylus tip tends to jump over several tracks or more. On the other hand, since the tracking pilot signal according to the present invention is selected to have a lower frequency band than the main information signal, it can be detected with relatively little aperture deterioration even while the needle is jumping. Furthermore, as explained in FIG. 7, the restoring force is provided by the servo over ±1.5 tracks. For the above two reasons, special playback modes such as stills can also be stably realized.

(9) This proposal describes the case where a single needle or head is used during recording and playback. However, it is also applicable when using multiple needles or heads. First, for a format in which a plurality of needles/heads whose scanning track positions can be independently and freely controlled are used only during playback, each playback needle/head is
It is clear that the embodiments described above can be applied independently to the head.

However, the present invention is also effective when applied to a system that records/reproduces a plurality of main information signals using a plurality of needles/heads whose scanning position intervals are fixed, and some application examples will be described later. .

The basic embodiment and its modifications have been described above. Next, a second embodiment will be described. In the basic embodiment, three or more types of tracking pilot signals for track discrimination are required, but in the second embodiment, these are simplified by using only two types of pilot signals, 0th and 1st. It is something that

In the order of explanation, the application target is a video disc, and how two types of discrimination signals are arranged on the information surface will be described first. FIG. 10 illustrates this arrangement. In the figure, the marks indicate the positions where the 0th and 1st tracking pilot signals are recorded, respectively. The symbol marked with is a pilot signal for indicating the recording position. As can be seen from the figure, the third (N+0) track includes 0, 1,
Each pilot signal is recorded periodically in the order of 4, 0, 1, 4, . . . . Each pilot signal is recorded periodically in the order of 4, 0, 1, 4, 0, 1, . . . on the (3N+1)th track. On the (3N+2)th track, each pilot signal is recorded in the order of 1, 4, 0, 1, 4, 0, . . . and so on. The recording position of each pilot signal is assumed to be the position corresponding to the horizontal synchronizing signal.

As can be seen from the arrangement in the figure, the 0th/1st tracking pilot signal is always recorded in the adjacent track after/before the recording position instruction pilot signal. Based on this discriminant logic,
Tracking is possible on the playback device side.

Note that when four fields of images are recorded per track revolution, the number of horizontal scanning lines corresponds to 1050 in the case of the NTSC system. Since this is an integral multiple of 3, in order to obtain the arrangement shown in FIG. 10, it is necessary to switch the recording order of the pilot signals every revolution of the disk. If you do not switch,
Each track ends up in an array of 0, 1, 4, 0, 1, 4, . . . , and it becomes impossible to determine the preceding and succeeding relationships of the tracks. For this reason, a timing pilot signal indicating a switching point for each cycle of each track is not shown in the figure, but is separately recorded and arranged as in the basic embodiment.

This concludes the explanation of the pilot signal arrangement diagram, and next, FIG. 11 shows the recording signal creation process. In this figure, parts having the same functions as those in FIG. 1 are indicated by the same numbers. 5' is the 0th pilot signal for tracking, 6' is the 1st pilot signal for tracking, and 7' is the pilot signal for recording position instruction, and their frequencies are the same as in the basic embodiment, for example.
0.6, 1.0, and 1.4MHz, respectively. 8' is a horizontal synchronizing signal. 9' is a switch. The switch 9' selects one of the three pilot signals as an output every time the horizontal synchronizing signal 8' is received in accordance with the order already described in FIG. Furthermore, the switching is performed in the order described above using a switching pulse 8 indicating a switching point for each rotation of the disk.

This concludes the explanation of the recording process, and next the reproduction process will be explained with reference to FIG. In this figure, the parts with the same numbers as in FIG. 5 mean the same functions, so the explanation will be omitted. In the figure, reference numeral 52 denotes a horizontal synchronizing signal separation and reproducing circuit, which is well known in conventional television technology, and obtains a horizontal synchronizing signal 53 at its output. 54 is a 1/3 frequency dividing circuit. At its output, a frequency-divided pulse train is obtained. The waveform is shown in FIG. Figure a shows a simulated horizontal synchronizing signal waveform, and its repetition period is approximately 64 μsec. b to c are frequency-divided pulse trains 56,
57, 58 waveform, repetition period is approximately 192μsec
It is. The pulse width is about 5μ, same as the horizontal synchronization signal.
sec. Divided pulse train 56, 57, 5
8 is the 12th gate signal for the (3N+1), (3N+2)) and (3N+3) tracks, respectively.
This is for applying to the gate circuit 55 in the figure. 56→57→58→56 of these pulse trains
The switching from →57 →58 . . . can be easily achieved by applying the timing pulse 42 detected and generated every cycle of disk rotation to the frequency divider 54. The reproduced signal gated by the gate circuit 55 is
The signal is applied to the discriminators 34' and 35'. Discriminator 3
4' and 35 each have a function of extracting the 0th and 1st pilot signals with frequency selection filters and detecting their amplitudes. Therefore, signals representing previous and subsequent information are obtained at each output. Therefore, the subtractor 38
to get the correct servo signal 39 at the output.

As is clear from the above description, in the second embodiment, it is not necessary to switch the filter characteristics, but instead it is necessary to switch the gate timing.

The above explanation is about normal mode playback. To perform still playback, simply use the divider 54
It is sufficient to stop applying the timing pulse 42 to. Therefore, like the basic example, it is extremely easy to
Therefore, it is superior to the prior art in that it can be achieved stably. I will omit the detailed explanation, but slow,
Special replay modes such as quick are also possible.

This concludes the explanation of the second embodiment, and next, the modification will be described.

(1) In this example, as in the basic embodiment, it is possible to record by increasing the width of the recording pit only during the 0th and 1st pilot signal recording periods, which is effective as a measure against adjacent track crosstalk. In particular, when recording using a light beam or an electron beam, instead of simply expanding the width of the pit, well-known optical deflection technology is used to pilot record the entire trajectory of the track pit in a predetermined direction. It is also effective to shift only the period. The predetermined direction in which it should be shifted is the direction in which it approaches the adjacent track, which is indicated by both the 0th pilot recording period and the 1st pilot recording period in FIG. That is, in FIG. 10, the track portion indicated by is shifted downward, and the track portion indicated by is shifted upward.

(2) In the second embodiment, the recording of the recording position instruction pilot signal shown in FIG. 10 may be omitted. This pilot signal can be detected separately in the reproduction system and used as an input gate signal to the gate circuit 55 in FIG. 12, but as explained in the second embodiment, it can be omitted. .

(3) The second embodiment has been described as an application to the NTSC system having a horizontal period of 1050 lines per rotation of the disk. However, in the PAL and SECAM systems, one period of disk rotation corresponds to 1250 horizontal periods (equivalent to 4 fields). And 1250 just happens to be not evenly divisible by 3, leaving a remainder of 2. Because of this property,
In the PAL and SECAM systems, the pattern shown in FIG. 10 can be naturally obtained without changing the recording order of pilot signals for each track revolution.
For example, the difference between the first pilot recording point and the lower point on the (3N+0) track is 1250 times the horizontal period. It can be seen that this leads to the 0th pilot. Therefore, when applied to the PAL/SECAM system, a timing pilot signal is not required.

(4) Although the second embodiment has been described as an application to a video disc, it can also be applied to recording/reproducing audio and other information. It can also be applied to VTRs.

Next, an example of application to recording and reproducing using a plurality of needles/heads will be explained.

In general, when K needles/heads are used to record and reproduce a set of K adjacent tracks at the same time, where K is an integer of 2 or more, the tracks at both ends of each set on the plane of the recorded medium are the same as those of the adjacent set. If three or more different tracking pilot signals are recorded on tracks that are adjacent to each other and adjacent to both end tracks, then during playback, one of the K playback needles/heads will be used. A servo signal 37 can be obtained by discriminating at least one output by the discriminators 34 and 35 shown in FIG. Of course, it is also possible to obtain servo signals from each of the K output stylus/heads, add these to obtain an average servo signal, and use this to control the entire regeneration stylus/head system. .

However, in a system using K needles/heads fixed to each other, it is not necessarily necessary to record three or more different tracking pilot signals, but simply two different tracking pilot signals as described below. It is sufficient to use the 0th and 1st tracking pilot signals, which is simpler.

First, if K is 3 or more, no tracking pilot signal is recorded on any one reference needle/head in the center excluding both ends. Then, the remaining K-1 needles/heads are divided into the front group and the rear group with the reference needle/head as the boundary, and the zero tracking pilot signal is sent to the front group, and the first tracking pilot signal is sent to the rear group. Assign pilot signals. During playback, the output of the reference needle/head is shown in Figure 5, 34 and 35.
A servo signal 39 is obtained by applying a discriminator similar to the above.
In the configuration of this discriminator 34, the switch 5 in FIG.
1 is not necessary and can be a fixed type filter that simply selects the first tracking pilot signal representing historical information. Further, the discriminator 35 corresponds to a fixed type filter that selects the 0th tracking pilot signal representing past information.

Therefore, the servo signal 39 can be obtained by configuring the discriminators 34 and 35 without a switch. 1st
The dotted line in FIG. 4 illustrates the discriminant theoretical characteristics in the case of K=5, with the vertical axis representing the servo signal and the horizontal axis representing the scanning track position of the center needle/head. In the same figure, the numbers written on the horizontal axis are the track numbers assigned to each group of K tracks, with negative numbered tracks receiving the 0th pilot signal, and positive numbered tracks receiving the 1st pilot signal. It's recorded. There may or may not be a space between both ends of each of the K groups, that is, a card band between the groups.

Next, in the case of K=2, 2
The following simplification method can be applied under the condition that an inter-group card band is provided for each track. The 0th pilot signal is recorded on the 0th track of the two tracks forming a pair, and the 1st pilot signal is recorded on the 1st track. When playing,
A servo signal is obtained by differentially comparing the first pilot signal detected from the 0th track reproducing needle/head and the 0th pilot signal detected from the first track reproducing needle/head. The relationship between the needle/head, scanning position, and servo signal in this case is shown by dotted lines in FIG.

A recent technical example of a plurality of needles/heads whose mutual relationship is fixed is a configuration example of a multi-spot laser recording/reproducing system shown in FIG. 16, which utilizes a plurality of semiconductor lasers. In the figure, 74 is a base body on which three laser light sources 75, 76, and 77 are mounted, and the intensity of each laser light is modulated according to the recording signal. 78 is a lens, and 79 is a rotating disk having a thin metal film on its surface, on which pit rows are formed in response to recording light. During reproduction, the well-known self-coupling effect of semiconductor lasers is used to control voltage changes at the supply current application terminals for each laser beam, which vary depending on the amount of each return beam modulated by the pit row. Detect and reproduce information. As a tracking actuator, there is a well-known technique, which is not shown in the figure, in which all of 74 to 78 in the figure are integrally displaced by electromagnetic force. The configuration of the present invention described above can be applied to such a system.

Incidentally, if such the latest semiconductor laser technology is used, it is possible to easily realize a pilot-dedicated beam in the prior art, which is the object of the present invention, and the effect of the present invention seems to be weakened. However, providing a separate pilot-dedicated beam makes the recording system expensive, and as already mentioned in this proposal, it is economically valuable to use this as the main information recording beam as well.

As described above, the present invention has the following advantages.

(1) In conventional recording and reproducing technology, when recording at high density on a disk, a light beam dedicated to recording tracking information is required in addition to the beam for recording main information, which poses problems in terms of cost and stability of storage devices. However, according to the present invention, the recording beam or the recording head can be integrated into one, thereby making it possible to reduce the cost and improve the stability of the recording apparatus. In addition, since it is no longer necessary to use two light beams, it is no longer necessary to use the photoresist photoresist film that was previously necessary for recording, which reduces the occurrence of disk defects that were associated with this. Easier to prevent.

(2) According to the present invention, tracking error detection can be achieved reliably and stably, and therefore stable reproduction of the main information signal is possible. Moreover, when applied to video discs, special playback mode can be stably realized.

(3) Tracking can be made possible with a simple configuration by applying it to a system that records and reproduces a plurality of main information signals using a plurality of needles/heads.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining the recording process of the present invention, and FIGS. 2 a to c are signal waveform diagrams of main parts.
3 is a plan view showing an example of the recording pit arrangement of the present invention, FIGS. 4 a to 4 c are pilot signal waveform diagrams corresponding to FIG. 3, and FIG. 5 is a block diagram for explaining the reproduction process of the present invention. 6 is a circuit diagram showing an example of a specific configuration of the discriminator 34, FIG. 7 is a tracking discrimination logic characteristic diagram, FIGS. 8 a to c are waveform diagrams of timing pulses, and FIG. 9 is a quadruple speed reproduction FIG. 10, an enlarged plan view of the track for explanation, is the second embodiment of the present invention.
FIG. 11 is a block diagram for explaining the recording method according to the second embodiment, FIG. 12 is a block diagram of the reproduction system, and FIG. 13 is a reproduction system diagram. 14 and 15 are tracking discrimination logical characteristic diagrams using multiple needles/heads, and FIG. 16 is a side view showing the main parts of the multi-spot laser recording/reproducing system. 2...FM modulator, 3...filter, 9,9'
...Switcher, 11...Gate, 31...Disk, 32...Pickup, 34, 35...Discriminator, 38...Subtractor, 41...Pulse generator, 4
4...FM demodulator, 61...operation control unit.

Claims (1)

[Claims] 1. The main information is in the form of a modulated high-frequency signal, which corresponds to the repetition of this modulated high-frequency signal, and is formed by optical means as a row of pits adjacent to each other with almost no gaps. In this method, a discrimination signal is superimposed in advance on the high frequency signal, and the size of the pit in at least the track direction is modulated with the discrimination signal, and the pit is recorded in a superimposed manner. A recording and reproducing method comprising a method in which a discrimination signal is made to have a difference in the frequency region occupied by the discrimination signal between mutually adjacent tracks, so that it is possible to determine the previous track arrangement and the subsequent track arrangement based on the difference in the frequency region. 2 The main information is in the form of a modulated high-frequency signal, and corresponding to the repetition of this modulated high-frequency signal, a large number of adjacent track shapes are formed as pit rows formed by optical means with almost no gaps between them. A discrimination signal having a different occupied frequency region between adjacent tracks is added to the modulated high-frequency signal recorded in time series, such that the size of the pit in the track direction is modulated by the discrimination signal. A device for reproducing main information from a recording medium recorded in a superimposed manner, which includes a plurality of discriminators for detecting the discriminating signal, and calculates the output signals of these discriminators to determine whether the track position has passed during scanning, A playback device that is characterized by determining whether or not it has passed.