JPS5833623B2 - Kougaku Teki Koumitsudokirokuhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a so-called video record, in which, for example, a video signal is recorded on a disc similar to an ordinary audio record.

Using a video signal, a frequency-modulated or pulse-frequency modulated uneven waveform was recorded in a spiral trajectory on a plastic disk, and the disk was rotated with a stylus in contact with the unevenness with appropriate pressure. At this time, a method has already been proposed in which the vibrations received by the stylus are converted into an electrical signal using, for example, a ceramic piezo element, and the signal is demodulated to reproduce a video signal.

The band of a video signal used in general television must be at least 3 MHz, and when frequency modulating this, the frequency range of the carrier is approximately 4 to 6 MHz.

This frequency is 200 to 300 times higher than the upper limit of general audio frequencies, ie, 20 kilohertz.

Generally, in the case of audio records, when cutting the master of the record, which is commonly called a lacquer disc, cutting is performed in real time, that is, at the same speed as the playback speed of the record.

This is because it is relatively easy to drive a record cutter at a frequency of about 20 kilohertz or even twice that frequency with current technology.

However, in the case of video signals, if you try to cut in real time, you have to drive the cutter at 4 to 6 MHz as mentioned above, and even if the cutting depth is less than 1 micron, current technology cannot do this. It is almost impossible to do so.

As mentioned above, an effective means of forming high-frequency irregularities in real time is recording on a photoresist thin film using a laser beam.

Figure 1 shows an example of a method for forming uneven waveforms on a photoresist thin film using a laser beam. 1 is a glass disk whose surface is coated with a positive photoresist, that is, a photodissolving type resist, with a thickness of several microns. It is driven by a drive motor 2.

A condensing optical system 3 is supported by a holder 4 in the vicinity of this disk.

The holder 4 has a feed screw 5 rotated by a feed motor 6.
The converging optical system can be moved in the radial direction of the disk.

The rod 7 is a guide rod that prevents the holder 4 from rotating around the axis of the screw 5.

The feed motor 6 and the disk drive motor 2 each have a drive motor (not shown in the figure) with a related rotational speed so that the radial pitch of the spiral, which is the trajectory on which the signal is recorded, reaches the desired value. Driven by circuit.

In the condensing optical system, the light from the laser 8 is transmitted to the optical modulator 9.
passes through an optical system 10 for enlarging the beam diameter,
Furthermore, the light is intercepted to enter through the reflecting mirror 11 supported by the protrusion 4-1 of the holder, and the light incident on this condensing optical system is passed through the cylindrical lens 12 as shown in FIG.
The light becomes linearly distributed light 14 by the condensing lens 13.

The linear distributed light 14 is applied onto the photoresist on the disk with its longitudinal direction almost matching the radial direction of the disk, and the light intensity changes over time as shown in FIG. 3 while rotating the disk. When the resist is exposed to light with A track with corresponding undulations is formed.

The reason why the grooves formed in the photoresist 15 take on the shape of a rain gutter is because
The distribution of the light energy of the linearly distributed light 14 in FIG. 2 on the resist surface is a mountain-shaped light whose distribution on the resist surface is represented by an equal energy distribution curve with the maximum value at the center, as shown in FIG. This is because it has a distribution.

To describe the connection between Figures 3 and 4, the black shaded area in Figure 4 is the area exposed to light corresponding to a + b in Figure 3, which is the deepest area. The area between the two shadows where the photoresist has been eluted is the area that has been exposed to light approximately corresponding to b.

Reference numeral 16 in FIG. 4 shows a cross section of the groove along the center of the recording trajectory, and the wavy unevenness appearing in the cross section corresponds to the change in light intensity shown in FIG.

Incidentally, the temporal change in the intensity of light as shown in FIG. 3 is achieved by driving the optical modulator 9 through an electric circuit (not shown).

The above describes how to apply vibration to the stylus through a rain gutter-shaped stylus guide and the bottom of its groove, as shown in Figure 4, by passing a laser beam through a suitable optical modulator and focusing optical system. The possibility of forming waveform irregularities is explained using a very simple case of temporal change in the intensity of light.

The signals recorded in this way are produced from lacquer discs in audio records by the same means used to manufacture ordinary records: a photoresist with recorded irregularities is coated with a silver mirror, and this is nickel-plated. By applying a mold and transferring the shape of the photoresist onto the surface of a disk such as polyvinyl chloride using this mold,
A record is made.

This is a video record, and an example of its reproducing means is as follows.

In FIG. 6, 17 is a video disk, and 18 is a motor for rotating the video disk, which is driven at a predetermined speed in the direction of arrow 19 by a power source (not shown).

20 is a pickup assembly for tracing the groove in which the signal is recorded and picking up the signal. The 7° holder 21 is connected to and supported by the holder 21 via an elastic body 25 such as rubber.The 7° holder 21 is for holder feeding. A screw 23 connected to the motor 22 is engaged with the screw 23 to move the pickup 20 in the radial direction of the record, and a guide rod 24 that controls the rotation of the holder around the screw 23.

The holder feeding motor uses a rotation drive circuit (not shown) to rotate the heater 18 so that the holder moves a distance corresponding to one pitch in the radial direction of the groove in which the signal is recorded per one revolution of the record. It is rotated in relation to

The details of the pickup assembly 20 are shown in FIG.

That is, at one end of a pipe 26 made of a light material such as titanium, both the long and short sides are several hundred microns and the thickness is several tens of microns, and electrodes 27.28 are placed on both sides.
One side of the piezo element 29 having a
A stylus 30 made of diamond, for example, is bonded to the other surface of the stylus 9.

The other end of the pipe 26 is connected to the holder 21 via an elastic body 25 such as rubber.

FIG. 7 shows the state in which the stylus 30 and the record 31 are engaged.

31-1 is a wave-like unevenness which is a signal provided on the surface of the record.If the record is fed in the direction of the arrow 32 in FIG. The portion 31-2 of the record that had been compressed by the stylus 30 is suddenly released, causing a sudden pressure change in the stylus 30.

This pressure change is transmitted to the piezo element 29 and taken out as an electrical signal through lead wires 33-1 and 33-2 drawn from the electrodes of the element.

The method of detecting such signals is significantly different from that of conventional audio records.

In other words, in the case of audio records, the stylus is attached to the tip of a cantilever such as a titanium pipe, and the entire cantilever moves according to the unevenness of the record groove. There are some that detect the movement of the stylus as osmotic force from the movement of a moving coil coupled to the cantilever near the stylus.

That is, in conventional audio pickups, the stylus itself follows the unevenness of the record almost faithfully.

In comparison, when detecting the video record signal described here, the cantilever pipe 2 in Fig. 7 is used.
6. The stylus holding system consisting of the elastic body 25 and the like is not designed to move in accordance with the individual waveforms of the unevenness 31-1 of the record, but rather is This is due to imperfections or imperfections in the record holding means of the record playback device.

The spiral 30 follows the vertical movement of the surface as the record rotates or the radial rocking of the spiral groove of the record, so that the spiral 30 always remains in the groove of the record and applies as uniform a pressure as possible to the groove of the record. designed to be pressed against the bottom of the

In video records, as mentioned above, the frequency of the modulation signal to be recorded ranges over several megahertz, so it is almost impossible to vibrate the cantilever itself at such a high frequency. If the cantilever pipe 26 is manufactured and rotated with sufficient flat support, the cantilever pipe 26
does not move up and down, but repeats the phenomenon that the convex part of the wavy concavity and convexity on the record surface is compressed by the stylus 30 and is released from the compressed state at the moment when it leaves the stylus 30-1. as terminal 33
-1.33-2.

When the detection means as shown in FIG. 7 is realized, the amplitude with which the cantilever pipe 26 can follow the vertical movement of the record surface has a property that it decreases significantly as the frequency of the vertical movement of the record surface increases. If there are fine ridges b and the surface of the record moves up and down at several tens of kilohertz as the record rotates, the amplitude that cantilever pipe 26 can follow is only about a few microns.

The above is an outline of the video record reproducing means, but when actually reproducing the wave-like irregularities recorded by the laser beam as described above, the following problems arise.

In the above explanations according to FIGS. 3, 4, and 5, the Q and Q' force direction distributions of the linearly distributed light in FIG. Although we have omitted consideration of the influence, the actual effect is as follows.

The state of the distribution of the linearly distributed light shown in Figure 5 is determined by the distribution of light incident on the focusing optical system, the numerical aperture of the focusing optical system, the focal length of the cylindrical lens, and the aberration of the focusing optical system. But that Q-Q'
When looking at the distribution of force in the direction, it often takes a shape roughly as shown in FIG.

The intensity of light itself is determined by the intensity that enters the optical system,
The distribution can be expressed in a normalized manner that is independent of intensity.

Therefore, when the intensity at the center is taken as one unit, the distribution can be sufficiently expressed by the intensity at a position r away from the center.

However, in the following explanation, only the QQ' cross section in FIG. 5 will be considered.

In the example shown in FIG. 8, there is a distribution 9 that is symmetrical to r=O and has a shape similar to the error function, and this is expressed as a function fl(r).

Now, as shown in Fig. 9a, the light beam having the distribution f1(r) has the relationship between the intensity I at its center and the position X as f2(x).
According to the relationship expressed by , if it moves horizontally from one end to the other at a constant speed in the figure, the amount of exposure received by the point X is J Cof2 (x+r)・fl(r)dr =f3ω
----(1) - Represented by two.

Figure 9 shows this situation. When the positional change in light intensity is trigonometric, when linearly distributed light passes through, it is easy to find the exposure amount at each position as follows.

In other words, when light with an intensity distribution as shown in Fig. 10 is passed through at a constant speed from X = -■ to The exposure amount E at each point of ,

As can be seen from FIG. 11 and equation (3), as ω becomes larger, the amount of variation in the exposure amount becomes smaller.

This means that, for example, when attempting to record wave-like unevenness on a photoresist, the amplitude of the recorded unevenness decreases as the recording wavelength becomes shorter.

Figure 12 shows an example that occurs when actually recording a video signal. When the intensity modulation is performed on the light beam as shown in a with respect to the groove position X of the record, that is, the center of the linearly distributed light is If the linearly distributed light passes at a constant speed in the horizontal direction in the figure while the intensity of the light around it takes the value shown by the chain line when it comes to each position of X, the exposure amount at each position of X is That is, the integral value of the luminous flux received by each position is as shown in FIG.

In other words, the period in which the light intensity changes is the light width 2 in Figure 8.
In the large part like S, that is, the part Pl, the exposure amount is saturated depending on the position of X, but in the part P2,
The convergence between the maximum and minimum exposure values is smaller than in the Pl portion.

The minimum value in P2 is larger than the minimum value in Pl, and the maximum value in P2 is smaller than the maximum value in Pl.

If such exposure is performed on the photoresist in the linear portion of the photoresist's exposure amount versus elution amount, that is, in the area where the photoresist is eluted in proportion to the exposure amount, the shape of the wavy uneven portion of the record will be as shown in Fig. 13. The height of the top of the part with a short wavelength is lower than the top of the part with a long wavelength of the wavy uneven part of the record.

Therefore, if the record is fed in the direction of the arrow 36, in order for the contact position of the stylus to move to the protrusion 35, the stylus needs a shorter time than it takes for the record to move the distance between the protrusions 34 and 35. It must be displaced downward by the height h in FIG. 11 in time.

Such a rapid displacement cannot be achieved due to constraints such as the mass of the stylus and cantilever pipe as described above, and the stylus glides above the convex portion 35 without coming into contact with it.

The position at which the stylus contacts the record again is determined by the ability of the stylus to follow the vertical movement.

When the stylus glides in this manner, it is of course impossible to detect a faithful modulation signal from the uneven portion, and a so-called dropout occurs in the video signal.

FIG. 14 shows a case where, contrary to FIG. 13, a short wavelength portion is followed by a long wavelength portion.9 In such a case, a significantly large pressure is applied to the convex portion 37. This may cause permanent deformation of the convex portion or significant wear on the stylus.

The present invention occurs when a modulated signal of a video signal is recorded using a laser as described above.

The present invention relates to means for eliminating fluctuations in the height of the top of a recorded waveform due to wavelength.

That is, in order to record the wave-like unevenness on the guide groove of the stylus and the bottom of the groove as shown in FIG. By applying a correction signal to the optical modulator to reduce the minimum value of the light intensity variation width, the height of the top of the convex part in the short wavelength part is made to be the same as the height of the top of the convex part in the long wavelength part. It is characterized by

Examples will be explained below.

In No. 15, a is a part of the video signal, and b is the voltage waveform of the carrier frequency-modulated to the video signal.

When this voltage is added to a constant DC voltage and a voltage having a functional relationship depending on the level of the video signal, a voltage as shown in C is obtained.

When this voltage is applied to the optical modulator shown in FIG. 1, the intensity at the center of the linearly distributed light obtained on the resist surface becomes a value proportional to the voltage waveform shown in C.

When this light is exposed onto the resist by rotating the disk 1 at a predetermined constant speed, the shape of the wavy unevenness obtained after development becomes as shown in the figure d.

In d, the heights of the lower ends of the waveforms are the same in the top view of each waveform on the resist surface.

When playing a record produced by transferring the waveform of the resist obtained in this way, Fig. 13, 1.
As shown in FIG. 4, the carrier signal is not engaged with the stylus, and the carrier signal can be detected smoothly.

FIG. 16 is a block diagram of a circuit for processing electrical signals as described above. An electrical signal from a video signal source 38, such as a video tape recorder, is applied to a frequency modulator 39 and is linearly linear with respect to the level of the video signal. It generates a voltage with a frequency that varies in relation to

FIGS. 17a and 17b show a video signal and its corresponding carrier waveform, respectively.

A DC bias power source 40 is a voltage to be applied to the optical modulator in order to obtain bias light for forming a gutter-like stylus guide groove, that is, light corresponding to the light beam in FIG. 3 described above.

Adding circuit 42 adds voltages from DC bias power supply 40 and frequency modulator 39.

The resulting composite electrostriction is as shown in FIG. 17C.

Meanwhile, a voltage from a video signal source is applied to processor 41.

Before explaining the processor, let's take a closer look at the recorded waveforms when there is no processor.

As the recording frequency increases, the amplitude of the amount of exposure onto the recording surface decreases as shown in equation (3).

The value of the exposure amplitude for a certain ω is expressed as Kc-ω, where K and k are constants.

Now, if we drive a modulator whose voltage and transmittance are proportional to voltage with a voltage that fluctuates at a constant amplitude as shown in FIG. Ke- becomes ω121 (4).

When the frequency is ωm, the amplitudes are the same.

Therefore, in order to make β as small as possible, the optical modulator may be driven with a voltage obtained by adding -a F 1 (Vrn) to the voltage shown in diagram C.

Here, the constant a is for obtaining resist elution of unit depth.
is the applied voltage to the optical modulator.

The processor 41 is a circuit for obtaining this aFl (vm), and the output from the processor 41 is a voltage with the polarity reversed as shown in FIG. 17C.

As described above, by varying the voltage in FIG. 17C with the voltage from the processor 41 in a relationship such that aF11'Vm) with respect to the video signal voltage, when the optical modulator is driven with a constant bias voltage and constant amplitude voltage, Fluctuations in the height of the convex portions of the resulting wavy unevenness on the record can be corrected.

This corrected waveform is shown in FIG. 17f.

Although Fl (vm) is used above to obtain the voltage to be applied to the adder circuit 42 in order to correct the above-mentioned step difference β, it is of course possible to obtain the correction voltage from the frequency of the modulated carrier.

In this case, according to equation (6), ω2 β = K (e 1 e - ωm) = F2 (ωm)...
...(9) is obtained.

The circuit configuration in this case is shown in FIG.

In the figure, 44 is a video signal source, 45 is a frequency modulator, and 4
6 is a DC bias power supply, and 38 in Figure 16 respectively.
．． It has the same functions as 40.

One of the outputs from the frequency modulator 45 is input to the processor to obtain aF2 (0m).

In addition, 47 is a delay line, which causes a time delay in analyzing the frequency modulated signal when obtaining the correction voltage in the processor. This is to give the carrier signal as much delay time as the processor requires for its process.

The reason why a delay line is necessary can be explained in more detail using an example as follows.

Assume now that the carrier modulated by the frequency modulator 45 is shaped inside the modulator and DC electrostriction is applied to it, resulting in an output as shown by the solid line in FIG. 19a.

Such a waveform is generally called pulse frequency modulation, but for the sake of simplicity, this waveform will be used for explanation.

If this voltage is applied to the modulator and the resist surface is exposed to light with a distribution as shown in FIG. 19 while moving at a constant speed, the amount of resist eluted will be as shown by the solid line in FIG.

As mentioned above, the heavy shape of the resist surface is as shown by the chain line in Figure C, and in order to obtain this, a voltage as shown by the chain line in Figure A is required.

This is the sum of the voltage shown by the solid line in figure a and the voltage shown in figure d, and is the sum of the voltage shown by the solid line in figure 3, C2.
, C3, that is, when there is a voltage change that would cause a narrow protrusion on the resist, a correction voltage as shown in Figure d must be generated.

However, whether or not a correction voltage as shown in figure d is required depends on C2.
It is still unclear at the time of the voltage change.

At the time when the voltage at C3 changes, it becomes clear that the correction voltage should have been generated from the time at C2.

Generating this correction voltage is the function of the processor 48, and the processor is required to predict carrier changes and generate a correction voltage in advance, but this is impossible. be.

However, in reality, by providing the delay line 47,
By delaying the time at which the change in the first point of carrier formation reaches the summing circuit compared to when that change enters the processor, the correction voltage found due to the subsequent change in It is possible to supply the resist to the addition circuit at the same time as the change, and thereby it is possible to obtain the amount of resist elution as shown by the chain line in figure C.

Here, we have explained the case where the transmittance of the optical modulator is proportional to the applied voltage, that is, the case of an ultrasonic optical modulator, but in the case of a so-called electro-optical modulator, the relationship between the applied voltage and the transmittance is is complicated.

Therefore, it goes without saying that the value of the correction voltage must take into account the characteristics of this modulation element.

As described above, the present invention deals with the sinking of the top of the wavy unevenness in the short wavelength region that occurs when the light intensity distribution created on the recording material by the condensing optical system is gentle, as a function of the video signal level or carrier frequency. By applying the obtained correction voltage to the optical modulator, correction is made in a flat manner across all recording frequencies. This is extremely effective when recording is performed optically.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a recording device that records information on a photoresist thin film using a laser beam, and FIG.
3 is an explanatory diagram illustrating temporal changes in light intensity, FIG. 4 is a partially sectional perspective view showing the signal locus formed on the recording medium, and FIG. 5 is a partially enlarged perspective view of the figure. An explanatory diagram showing the beam energy distribution on the recording medium, FIG. 6 is a perspective view of a reproducing device that reproduces information on the recording medium, and FIG. 7 is used to explain the pickup of the reproducing device shown in FIG. 6. In the figures, a is a side view, b is an enlarged perspective view, FIG. 8 is an explanatory diagram showing beam energy distribution, and FIGS. 9 a, b, and 10.
The figure is an explanatory diagram for explaining light intensity exposure amount and energy distribution, FIG. 11a. b is a drawing for explaining the light intensity and exposure amount, FIG. 12 is an explanatory drawing for explaining the exposure amount of the recording medium, FIG. 13,
FIG. 14 is an explanatory diagram showing signal traces formed on a recording medium, and FIGS. 15 a, b, c, and d are diagrams showing signal waveform diagrams and resist elution depths used in the present invention. FIG. 16 is a block tiagelum for explaining the recording method according to the present invention, and FIG. 17 a % f is an explanatory diagram for explaining the recording method shown in FIG. 16. FIG. 18 is a block tiagelum showing another embodiment of the recording method according to the present invention. FIG. 19 as b sc * d is an explanatory diagram of the present invention. Here, 38.44 is a video signal source, 39°45 is a frequency modulator, 41.48 is a processor, 40.46 is a DC bias power supply, 42.49 is an addition circuit, 43.50 is an optical modulator, and 47 is a It is a delay circuit.

Claims (1)

[Claims] 1. A carrier frequency-modulated to the recording edge signal such that the frequency increases in response to a change in the recording signal level in a certain direction, and An optical high-density recording method characterized by driving a light modulation element with a correction signal that reduces the amplitude of modulated light. 2. Adding to a processor a delayed signal obtained by delaying a carrier frequency-modulated by the recording edge signal so that the frequency increases in accordance with a change in the recording edge symbol level in a certain direction, and a recording signal or a carrier to obtain a signal from the processor. An optical high-density recording method, characterized in that the optical high-density recording method is characterized in that a correction signal is used to reduce the amplitude of the modulated light in response to a change in the recording signal level in the certain direction.