JPS6329336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a recording method that performs recording by scanning a recording medium with light.

[Technical background]

In a method for optical high-density recording, the drive signal voltage applied to the light intensity modulator and the modulated light intensity are proportional, and the modulated light intensity sufficiently responds to temporal changes in the drive signal voltage. Even if it is possible, in a recording medium in which the recording state with respect to the exposure amount has a threshold value, the recording pattern actually recorded and the pattern of the recording signal will not be the same for reasons described later. This means that, for example, when a recorded pattern obtained on a recording medium is photoelectrically converted to transmitted or reflected light using a reproducing light spot to obtain a reproduced electrical signal, the recorded signal cannot be accurately reproduced. In extreme cases, recorded information may be reproduced by mistake.

〔the purpose〕

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method capable of forming a recording pattern on a recording medium that is equivalent to a recording signal. It is something that can be achieved.

〔Example〕

The details of the present invention will be explained below with reference to the drawings. First, in FIGS. 1 to 8, the case of a recording medium in which the recording density is proportional to the exposure amount will be explained, and in FIGS. 9 to 12, a signal recording method for a recording medium having a threshold value according to the present invention will be explained. explain.

Figure 1 shows a recording method using laser light as one of optical recording methods, where 1-1 is a laser light source and 1-21 is a constant unmodulated light intensity emitted by the laser light source. laser beam,
1-3 is an optical modulator that utilizes electro-optic effects or electro-acoustic effects such as known KDP and ADP. 1-22
1-4 is a beam expander for expanding the diameter of 1-22 into the laser beam, 1-23 is the expanded laser beam, and 1-5 is a laser beam that combines the laser beam 1-23. A focusing optical system is arranged to form a minute optical spot for imaging, and 1-24 is a focused laser beam. 1
-25 is a light spot formed by this focusing optical system, and 1-6 is a recording medium.The following description will be made by taking a silver salt film as an example. 1-7 is an arrow indicating the moving direction of the recording medium, 1-8 is an input terminal for recording signal voltage, 1-9 is a known PFM modulator used in VTRs, etc., and 1-10 is a PFM modulator. This is a power amplifier for the recorded signal voltage. Therefore, the recording signal voltage input to input terminals 1-8 is
The power is PFM-modulated by the PFM modulator 1-9, and is amplified by the power amplifier 1-10 to a power that can drive the optical modulator 1-3, and is input to the optical modulator 1-3 as a driving signal voltage. A laser beam 1-21 from a laser light source 1-1 is intensity-modulated by an optical modulator 1-3 and becomes a laser beam 1-22. The diameter of the laser beam 1-22 is expanded by the beam expander 1-4. As is well known, the function of the beam expander 1-4 is based on the wavelength of the laser beam and the focusing optical system 1-5 in order to obtain a minute light spot.
This is because the diameter of the incident light beam is related, and if the wavelength is constant and the focal length of the focusing optical system is constant, the larger the diameter of the incident light beam, the smaller the obtained light spot. The laser beam 1-23 is imaged by a focusing optical system 1-5 as a minute spot 1-25 on a recording medium 1-6 moving in the direction of arrow 1-7, and recording is performed on the recording medium. In the following explanation, the drive signal voltage of the optical modulator 1-3 and the light intensity of the laser beam optically modulated by the drive signal are photoelectrically converted by a photoelectric converter such as a photomultiplier tube. It is assumed that the electrical signals are similar.

Under the above assumption, the drive signal voltage is
The relationship between E _io and the laser beam intensity I _put is I _put ∝
sin ² E _io , and it is possible to correct this nonlinearity by correcting the drive signal voltage in advance, or by negative feedback using an electric signal obtained by photoelectrically converting the modulated laser beam. Therefore, it is clear that this assumption is not inappropriate for explaining the gist of the present invention. Next, a perspective view of FIG. 2-1 shows the exposure state of the recording medium 1-6 in such a case.

In addition, in Figure 2-1, the point shown as minute light spot 1-25 in Figure 1 is enlarged, and the irradiance of light within this light spot is shown for ease of explanation. Assume that I is uniform and I ₀ . At the moment t ₂₁ , light spot 1-2
The position on the recording medium 1-6 of 5 is the light spot 1-2.
The center of 5 is B, and the points that pass through this point B and intersect with the outer periphery of spot 1-25 on line segment 1-7 indicating the direction of movement are A and C as shown in Figure 2-1. Let the diameter be _d2 .) Now let the moving speed of the recording body 1-6 be v, and let the time τ ₂₁ for the recording body to travel a distance equal to the diameter d ₂ of the optical spot 1-25 be,
At time _t21 , the drive signal voltage _E2 is applied to the optical modulator 1-
Assume that E _{nax2 is such that the laser beam can pass through E nax2} (as shown in Figures 2-3), and the case where the duration t ₂₃ of E _nax2 , that is, the exposure time is t ₂₃ >τ ₂₁ will be considered. Generally, the amount of exposure P given to the recording medium 1-6 is expressed by the product P=I ₀ t of the irradiance I ₀ and the exposure time t.

Therefore, the point to the left of point A is I ₀ = 0, so P = 0
Since point C is t=τ ₂₁ , P=τ ₂₁ I ₀ ,
Moreover, since t=τ ₂₁ /2 at point B, P=τ ₂₁ /2I ₀ .

That is, the exposure amount at each point on the line segment is given by the product of _I0 and the time it takes for each point to be exposed from time _t21 until light spot 1-25 passes through that point. , this situation is shown in Figure 2-2.

In addition, the horizontal axis in Figure 2-2 is the same axis as the extension line of line segment AC, and the unit is length, and each point of A'B'C'...corresponds to ABC... in Figure 2-1. It indicates the location.

Next, after time t ₂₃ has elapsed, at time t ₂₂ the drive signal voltage becomes _Enio2 , the laser beam is cut off, and exposure is stopped.
At time _t21 , point A on the recording medium has reached the same position, and point E, which is a distance _d2 from point D, is at the same position as point C at time _t21 .
It is clear that the exposure received by each point between points D and E follows the opposite course of the exposure of each point between points A and C, and therefore, as shown in Figure 2-2.
The change in exposure state during D′E′ is symmetrical to that during A′C′.

Here, line segment d ₂ = A′C′, line segment = Vt ₂₃ −d ₂ ,
The following relationships hold: line segment = d ₂ = D'E', line segment = Vt ₂₃ = A'D', and line segment '' = Vt ₂₃ + d ₂ .

The point to note in the above explanation is that even if exposure starts or ends at an infinite speed, at that point the exposure amount will change by d ₂ /2 in the direction of movement of the recording medium relative to the center of the light spot. This means that there are some things that are changing.

Next, FIG. 3 shows a recording state using a drive signal voltage consisting of a continuous pulse train with a constant repetition period. In the following description, it is assumed that recording is performed in a region where the recording density D of the recording medium, ie, the silver salt film, is linearly proportional to the product of the irradiance of the light spot and the exposure time, that is, the amount of exposure.

Figure 3-1 shows the temporal change of the drive signal voltage _E3 input to the optical modulator, which has a repetition period T, a waveform with a symmetrical light irradiation time _tp , and It is assumed that the maximum value of the drive signal is _Enax3 and the minimum value is _Enio3 .

Figure 3-2 shows the temporal change in the radiation intensity of the modulated laser beam passing through the optical modulator, assuming that the driving signal voltage and the modulated laser beam radiation intensity are proportional as described above. are shown as _Inax3 corresponding to _Enax3 and _Inio3 for _Enio3 , respectively. Third
Figure 3 shows the amount of exposure given to the recording medium by the laser beam, and the horizontal axis of the coordinates corresponds to the horizontal axis of Figures 3-1 and 3-2, that is, l = Vt, which corresponds to time. It is indicated by the distance l connected by the relational expression. In the figure, if the distance at which the exposure corresponding to the maximum amount of exposure is given on the recording medium is l ₁ , then the moving speed is V, and it is given by l ₁ = Vt _p - d ₃ (here, d ₃ is the distance of the light spot). It is assumed that there is a relationship of d ₃ /V=t _p2 .)

Note that, based on the assumption of the exposure amount and density, the distance change in the density recorded on the recording medium is similar to that shown in FIG. 3-3, as shown in FIG. 3-4. Next, the fourth section describes the case where the pulse width t _p changes from t _p41 , t _p42 , t _p43 (however, it is a symmetrical rectangular wave with periods T ₄₁ , T ₄₂ , T ₄₃ ) (T ₄₁ > T ₄₂ > T ₄₃ ). This will be explained with reference to the figures. Note that the relationship between the horizontal axes in FIG. 4 is the same as in FIG. 3, and since the drive signal voltage and the light radiation intensity are similar, the diagram showing the radiation intensity is omitted. In Figure 4-1, 4-1a is
t _p41 ≫d ₃ /V, 4-1b is t _p42 = d ₃ /V, 4-1c is t _p
43 ≪d ₃ /V. In the case of 4-1a, as is clear from the explanation of FIG. 3, the exposure amount changes as shown in FIG. 4-2, 4-2a, and the resulting density change on the recording medium is as shown in FIG.
-3a. Next, when t _p42 = d/V, the flat part disappears in the exposure amount as shown in Fig. 4-2, Fig. 4-2b, but the maximum value of the exposure amount is as shown in Fig. 4-2, Fig. 4-2.
2a is the same value P _nax4 , and it is clear that the resulting density change on the recording medium is as shown in FIG. 4-3, 4-3b. In the case of t _p43 ≪ d ₃ /V, the rise and fall of the exposure amount uniquely depends on the moving speed V of the recording medium, the diameter d ₃ of the light spot, and the amount of change in the exposure amount (P _nax4 − P _nio4 ). Therefore, as shown in Figure 4-2c, _the exposure amount is
Before reaching P _nax4 , it is affected by the rising time of the time corresponding to the next drive signal voltage E _nio4 , and similarly before reaching P _nio4 , the rising time of the time corresponding to the next drive signal voltage E _nax4 4-2a, 4-2 in Figure 4-2.
This results in a decrease compared to the case of -2b. The density change on the recording medium in this case is shown in Figure 4-3.
It is clear that a recording density corresponding to P _nax4 and P _nio4 cannot be obtained.

The above explanation is for the case where the drive signal voltage is constant, but from a different perspective, how to make the amount of change in recording density on the recording medium constant even if the pulse repetition period T changes? Consider what kind of drive signal voltage should be applied. Figure 5-1 shows the recording wavelength on the recording medium, that is, the sum of the high and low density distances, L ₅₁ , L ₅₂ , L ₅₃ , and the density when the high and low density distances are equal. Indicates the ideal recording pattern of change. However, even if the rise and fall of the drive signal voltage were infinitely fast, it would be impossible to obtain the recording pattern shown in Figure 5-1 because the diameter of the light spot is finite. An example of the case where the maximum and minimum values of the density obtained in the recording pattern that can be realized when the diameter is equal to l ₅₂ shown in Figure 5-1 are approximately constant regardless of the recording wavelength. It is shown in Figure 5-2. Here, in 5-2c,
Due to the above-mentioned limit on the diameter of the light spot and the condition that the concentration is constant, the positional gradient of the concentration is steep, and l ₅₃ =
In the case of 3/2l ₅₂ , the slope is 1.5 times that of 5-2b. Since Fig. 5-2 corresponds to the temporal change in exposure amount, Fig. 5-3 shows the temporal change in the drive signal voltage necessary to provide such exposure, and 5-3a , 5-3b are each 4-1
This corresponds to a, 4-1b. In addition,
In Figure 5-3, the relationship with Figure 5-1 is
They are connected by l ₅₃ =Vt _p53 , and the same is true for t _p52 and t _p51 .

In 5-3c, the drive signal voltage is increased in order to make the temporal change or slope of the exposure amount more rapid than in the former two as described above. That is, in Figure 5-3, if T ₅₂ = 3/2T ₅₃ (t _p52 = 3/2 t _p53 ), the slope of 5-2c is 5-2a, 5
-2b is 3/2 times that of the case (after all, the slope at 5-2c = P _nax5 - P _nio5 /t _p53 = 3 (P _nax5 - P _nio5 )/2t _p52 ), so , it is clear that the drive signal voltage E needs to be 3/2 (E _nax5 -E _nio5 ).

As described above, in order to keep the recording density on the recording medium constant regardless of the cycle of the drive signal voltage, it is possible to achieve this by correcting the drive signal voltage in relation to its repetition cycle. Prove.

However, although the above explanation deals with a steady state, that is, a case where the periods of the drive signal voltages are different, it does not take into account changes in the temporal period, that is, a transient state.

A more detailed explanation will be given regarding the correction means for forming a desired recording pattern on the recording medium when the period changes over time, that is, when it changes on the recording medium in a transient state, that is, in a transient state.

FIG. 6 shows a "desirable recording pattern" on a recording medium based on a recording pattern of an arbitrary recording wavelength. Here, a "desirable recording pattern" is one in which the recording density changes with a maximum value D _nax61 and a minimum value D _nio61 with respect to the drive signal voltage of every cycle, that is, the recording length in Figure 6-1. , and means that the concentration change at the end from D _nio61 to D _nax61 , or vice versa, is infinitely steep.

In some cases, the term "desired recording pattern" may mean a recording pattern that is intentionally created, for example, a recording in which the density change at the edge has a constant slope rather than an infinitely steep change. It is also possible. However, in these cases as well, the "desirable recording pattern" defined in this explanation is changed to a "less desirable recording pattern," so it is important for the present invention that the following explanation is based on the "desirable recording pattern." It does not impose any restrictions on the subject matter.

Figure 6-2 shows that a recording pattern made as shown in Figure 6-1 is scanned using a reproduction light spot with a finite aperture and uniform irradiance, and changes in density are measured by photoelectric conversion. (The horizontal axis t is the time axis related to the scanning speed V _s during reproduction by l = V _s t, Considering that V _s is equal to the moving speed V of the recording medium in FIG.
The time axes of FIG. 4, FIG. 5, and FIG. 6 are the same. ). In Fig. 6-2, it is assumed that the reproduction output voltage has been corrected to be linear with respect to the density, and time points t ₆₁ , t ₆₂ ... t ₆₁₀ represent the occurrence of density changes on the recording medium. The case is shown in which the center of the reproduction light spot passes through the position shown in _FIG .

In FIG. 6-1, the reproduction output voltage for the portion where the recording length is l ₆₁ , l ₆₂ , and l ₆₉ with high density is E _nax61 or E _nio61 as shown in FIG. 6-2. It has a flat part. Also, record length
The reproduced output voltages corresponding to l ₆₃ and l ₆₈ do not have a flat part, but have a peak reaching E _nax61 or E _nio61 .

However, the reproduction output voltages corresponding to l ₆₄ , l ₆₅ , l ₆₆ , and l ₆₇ are 4-1c and 4-2 at the time of recording.
As can be inferred from c and 4-3c, it is clear that the amplitude of the reproduced output voltage decreases without reaching E _nax61 or E _nio61 .

On the other hand, in the case of a recording pattern as shown in Figure 6-1, for example, if this recording pattern corresponds to an FM modulation signal such as that known in VTRs, the modulation signal, that is, the original information, is converted into a change in frequency. On the recording medium, the recording length of l ₆₁ , l _{62 .} . . l ₆₉ is related to the original information, and therefore, in FIG _.
...It is considered that the original information is related to the reproduced output voltage at each point in time t ₆₁₀ .

Also used when recording digital data on magnetic tape, magnetic cassette recorder, etc.
In the NR21 method, PE method, etc., the digital data, that is, the original information, is the maximum density value, minimum value D _nax61 , D _nio61 , and recording length of l ₆₁ ... l ₆₉ on the recording medium in Figure 6-1. and _density change position No. _6-3 .
In Figure 2, E _nax61 , E _nio61 , time t ₆₁ ...
...It is thought to be related to the reproduction output voltage at t ₆₁₀ .

The importance of the reproduced output voltage, the amplitude value of the reproduced output pressure, etc. at the time points t ₆₁ ... t ₆₁₀ mentioned above is not only important in recording FM modulation signals or digital data signals, but also in recording all kinds of information. Needless to say, this also applies. In the case of digital recording, in order to identify 0 and 1 in a digital signal, there is a range of allowable densities corresponding to 0 and 1, and therefore the density does not necessarily have to be maximum or minimum.

Fig. 6-3 shows that in consideration of the above points, the maximum value of the recording density is close to the maximum value of the possible range, and the minimum value is also An example of a desirable recording pattern that is similarly possible under the constraints of keeping the value constant regardless of the recording length and recording with a light spot having a finite diameter is shown below.

Points to note in Figure 6-3 are times t ₆₄ , t ₆₆ , t ₆₇ ,
At each position on the recording medium corresponding to _t68 , the slope of the density change must be 4/3 times as large as that in Figure 6-2.

FIG. 6-4 shows the drive signal voltage E of the optical modulator that is desirable for obtaining a recording pattern having the density change shown in FIG. 6-3. Particular attention should be paid here to the time
The falling time t ₆₁₁ of the drive signal voltage corresponding to t ₆₄ and the rising time t ₆₁₂ of the same at time t ₆₉ , and the sixth
−4 Time t ₆₁₁ shown in the figure is delayed by time τ ₆₁ from time t ₆₄ ,
Also, time t ₆₁₂ is a point that is ahead of time t ₆₉ by τ ₆₂ . Now, in Figure 6-3, record length along the horizontal axis
Consider the case where a light spot with a diameter d ₆ equal to l ₆₃ is moved in the direction of the arrow on the coordinate axis and recording is performed. In the density change at the position corresponding to time t ₆₁ in Fig. 6-3, the distance between the density rising position x ₆₁ and the position x ₆₃ where the density becomes constant is equal to the diameter d ₆ of the light spot, and therefore , when the light spot moves along the coordinate axes and the center of the light spot is located at position _x62 , the drive signal voltage is set to E _nio62 as shown in Figure 6-4.
By changing the value to E _nax62 , recording from position x ₆₁ to x ₆₃ shown in the 6-3 diagram is performed. Also position x ₆₄
The same is true for records near . However, at time t ₆₄
At x _{65 , which corresponds to}
If the drive signal voltage is changed from E _nax62 to E _nio63 , the density gradient will certainly be 4/3 times, but the position where the density change starts will be _x65 ', resulting in a recording pattern as shown in Figure 6-3. Must not be. The way to prevent such a recording pattern is to change the driving signal voltage from E _nax61 to E _nio63 by adjusting the time required for the light spot to move from position x ₆₅ ' to x ₆₅ '' as τ ₆₁ = x ₆₅ '. This can be achieved by delaying the distance by x ₆₅ ″/V _s . That is, time t ₆₁₁ , which is delayed by time τ ₆₁ from time t ₆₄ , is the time when the drive signal voltage is changed in order to perform the desired recording shown in Figure 6-3. Furthermore, the method for obtaining the concentration gradient at position _x66 can be considered in the same way as above. No. 6-5
A recording pattern based on the corrected drive signal voltage shown in FIG. 6-4 is shown in FIG. 6-6, and a recording pattern based on the uncorrected drive signal voltage is shown in FIG. 6-6, showing that the correction is effective. The recording pattern in the section between positions x ₆₆ and x ₆₇ in FIG. 6-5 will be further explained with reference to FIGS. 6-7 and 6-8. 6th-
In Figures 7 and 6-8, the horizontal and vertical axes have been enlarged twice, and the time points entered are as shown in Figures 6-1 to 6.
- Same as Figure 6. Time points in Figures 6-7
The change in the drive signal voltage from E _nax63 to E _nio63 at t ₆₈ can be used as is to obtain the concentration gradient at position x ₆₆ in Figure 6-8, but the next time the drive signal voltage changes at t ₆₉ . If this setting is made, the concentration gradient obtained will be as shown by the dotted line 61 in FIG. 6-8. In such a state, although it is desired to set the recording density to vary around the line 62, the position where the dotted line 61 passes through the line 62 is x ₆₇ ', which causes an error. The change point of the drive signal voltage is _t69
If we proceed further to t ₆₁₂ , this error can be corrected as shown by the solid line 63 in Fig. 6-8, but in the part 64, the exposures at time t ₆₈ and time t ₆₁₂ overlap and the exposure at time t 6-8 is
As shown in the figure, a flat portion occurs and does not reach D _nio61 , but the amount is not particularly problematic. To summarize the above explanation, if the recording length l _s on the recording medium is the optical spot d used for recording, if l _s > d, the drive signal voltage does not need to be corrected, but if l _s ≦d, the drive signal voltage In particular, when the recording wavelength _ls changes transiently, it is necessary to change the amount of change in the drive signal voltage and the point at which the drive signal voltage is changed (hereinafter referred to as the correction point). It is. In particular, in the latter case, the correction time point is determined based on the state of the drive signal voltage past the correction time point.
That is, it is determined by the duration of _Enax or _Enio and the state of the drive signal voltage that will occur next, ie, the duration of _Enax or _Enio .

FIG. 7 shows a configuration diagram as a specific embodiment of the present invention. In the following description, the recording conditions, such as the moving speed of the recording medium, the diameter of the light spot, and the fact that the recording medium is a silver halide film, are all the same as those used in the description of FIG. 7-1 is the input terminal for the recording signal to be corrected, and 7-2 is the input terminal for the recording signal to be corrected.
OR circuit 7-3 is a triangular wave generator consisting of a known integrating circuit, etc. 7-4 is a sampling circuit which may have a known circuit configuration; 7-5 is a sampling pulse generator such as a trigger-type blocking oscillator. 7-6 is an inverting amplifier, which is a normal amplifier in which the input and output maintain a linear relationship and are in reverse phase, 7-7 is an OR circuit, and 7-8 is a 7-8 amplifier.
7-9 is a sampling circuit similar to 7-4, 7-10 is a sampling pulse generator similar to 7-5, 7-11 is a discriminator that uses a diode, etc. 7-12, 7-14 are ordinary amplifiers, 7-13 is an amplifier such as a Schmitt circuit, 7-15, 7-16, 7-17, 7- 18
7-19 is an inverting amplifier similar to inverting amplifier 7-6; 7-20 is a gate signal present time; 7-19 is an inverting amplifier similar to 7-6; This is a known circuit such as one using a diode bridge, for example, which outputs only one input. 7-21 is an inverter, 7-22 is
AND circuit, 7-23 is a set-reset type flip-flop, 7-24 is an inverter, 7-25 is a
AND circuit, 7-26 a delay line with a fixed delay time, 7-27 a set-reset type flip-flop, 7-28 an OR circuit, 7-29,
7-30, 7-31, and 7-32 are AND circuits. 7-33, 7-34, 7-35, 7-3
6 is an inverter, 7-37, 7-38 are
7-41 is an OR circuit; 7-39 is a set-reset type flip-flop; 7-40 is an OR circuit;
7-42 is a variable amplification factor amplifier, and 7-42 is a delay line with a fixed delay time. , 7-43 is a pulse generator similar to the sampling pulse generator 7-5. 7-44 is a delay line with a fixed delay time, 7-45 is a sampling circuit similar to 7-4, 7-46 is a shaping circuit such as a Schmitt trigger circuit, 7-47 is an inverter, 7-48 is an OR circuit, 7-49 is an AND circuit, 7-50 is an inverter, 7-51 is a sampling circuit similar to sampling circuit 7-4, 7-52 is an OR circuit, 7-53 is an AND circuit,
7-54 is a delay line with a fixed delay time; 7-55 is a sampling pulse generator similar to sampling pulse generator 7-5; 7-55 is a sampling pulse generator similar to sampling pulse generator 7-5;
56 is an output terminal for deriving the corrected recording signal voltage.

Next, the operation of each part will be explained with reference to the waveform diagram in FIG.

An example of the recording signal voltage (hereinafter abbreviated as signal) applied to the input terminal 7-1 to be corrected is shown in the 8th-
As shown in Fig. 1, the points of rising and falling of the signal, that is, the points of change, are t ₁₀₁ , t ₁₀₂ , etc., and the time t ₁₀₁ ~
t ₁₀₂ = t ₁₀₂ ~ t ₁₀₃ = t ₁₀₉ ~ t ₁₁₀ , t _{103 ~ t 104} = t ₁₀₈ ~
t ₁₀₉ , t ₁₀₄ ~ t ₁₀₅ = t ₁₀₅ ~ t ₁₀₆ = t ₁₀₆ ~ t ₁₀₇ = t ₁₀₇ ~ _{t 1
08}
, t ₁₀₁ - t ₁₀₂ = 2 (t ₁₀₃ - _{t 104} ), t ₁₀₃ - _{t 104} =
4/3 (t ₁₀₄ - t ₁₀₅ ). One of the signals is input to the OR circuit 7-2 and the sampling pulse generator 7-5, and the sampling pulse generator 7-5 generates a sampling pulse 1 with a pulse width τ ₁₀ at the falling edge of the signal.
(shown in Figure 8-2), which is the OR circuit 7-
2, therefore the output of the OR circuit 7-2 is the 8th
-3 As shown in the figure, a waveform whose falling point is delayed by τ ₁₀ is input to the triangular wave generator 7-3 and the sampling circuit 7-4. Figure 8-4 shows the integrated voltage waveform (integrated voltage 1) generated by the triangular wave generation circuit 7-3, and the flat part of the time corresponding to τ ₁₀ at the peak of the triangular waveform is such that the sampling operation is reliable. For example, in an integral operation such as charging a capacitor with a constant current and obtaining a triangular waveform depending on the terminal voltage, a circuit that causes a discharge current equal to the charging current to flow out from the capacitor at τ ₁₀ . This can be achieved with The integrated voltage 1 is sampled by a sampling circuit 7-4 using known means, according to the sampling pulse 8-2 from the sampling pulse generator 7-5, and the peak of the integrated voltage 1 is detected by a hold capacitor (not shown). The voltage on the flat part is held. On the other hand, the sampling pulse 2 having a width τ ₁₀ ' approximately equal to τ ₁₀ generated at the rising edge of the signal applied to the sampling pulse generator 7-10 via the inverting amplifier 7-6 is the 8-5th pulse.
The output waveform is generated as shown in the figure, and an output waveform as shown in FIG. 8-6 can be obtained by the triangular wave generator 7-8 in the same manner as described above. sampling circuit 7-4,
Since a hold capacitor (not shown) is commonly provided to the outputs of 7-9, the terminal voltage of the hold capacitor is as shown in Figure 8-7.
E _101,102 ... ₁₀₉ . here
E ₁₀₁ = E ₁₀₂ = E ₁₀₉ , E ₁₀₃ = E ₁₀₈ , E ₁₀₄ = E ₁₀₅
= E ₁₀₆ = E ₁₀₇ . As mentioned above, the pulse width that requires correction is determined by the moving speed of the recording medium and the time between signal change points, that is, the pulse width and the diameter of the optical spot used for recording.
-7 The sampling voltage shown has a certain value corresponding to the pulse width that requires correction, and in this example, it is E ₁₀₃ corresponding to times t ₁₀₃ and t ₁₀₄ . The discriminator 7-11 has a function of outputting only when the sampling voltage is smaller than _E103 , and its output is shown in Figure 8-8.
The output shown is called the correction voltage). The correction voltage is 7
-12, 7-13, 7-14 are input to each amplifier, and 7-12, 7-14 corrects each output with a linear amplifier that maintains a linear relationship between normal input and output. The voltages 1 and 3 and the amplifier 7-13 are, for example, Schmitt circuits that output ON-OFF signals, and this output is called a correction voltage 2 (shown in Figures 8-9). 7-15, 7-16, 7-17, 7-1
8 are variable delay lines, respectively, and gate circuit 7-2.
7-15 and 7-17 are those whose delay time decreases as the control voltage increases, and 7-15 and 7-17 are those whose delay time decreases as the control voltage increases, depending on the combination with the output of 0.
-16 and 7-17, the control voltages have opposite phases due to the inverting amplifier 7-19, and therefore the delay time increases. The correction voltage 2 of the amplifier 7-13 is applied to the flip-flop 7-23 and the inverter 7-2.
4 and is input to flip-flop 7-27.
The flip-flop 7-23 is set at the falling edge of the signal shown in FIG.
27 is set at the rising time by the inverter 7-24. On the other hand, the OR circuit 7 generated at the rising and falling points of the corrected signal obtained as described later
-40 is input to 7-22 and 7-25, therefore, flip-flop 7-23 is set at time _t105 when correction voltage 2 is generated, and then the output from OR circuit 7-40 (8th -12 diagram 10a)
is reset by flip-flop 7-27.
is set at the time _t108 when correction voltage 2 ends,
Output from OR circuit 7-40 (10 as shown in Figure 8-13)
b), the Q output of flip-flop 7-23 is as shown in FIG. 8-10, and the Q output of flip-flop 7-27 is as shown in FIG. 8-11. Incidentally, since the delay line 7-26 has a delay time τ ₁₁ approximately equal to the times τ ₁₀ and τ ₁₀ ', the input of the OR circuit 7-28 has the 8th-
11 As shown in the diagram, time t ₁₂₁ is delayed by τ ₁₁ from time t ₁₀₈ .
A signal having a pulse width up to time t ₁₂₂ delayed by τ ₁₁ from time t ₁₂₄ , which will be described later, is applied. The Q output of each flip-flop 7-23, 7-24 is an OR circuit 7.
-28 and input to the gate circuit 7-20, and the correction voltage 3 from the amplifier 7-14 is output only when the pulse exists. This output passes through each variable delay line 7-15, 7-17 and an inverting amplifier 7-19.
6, 7-18. Variable delay line 7
-15, 7-17 is shown in 8-10 and 8-
11 The delay time is controlled only for the first pulse input to the variable delay lines 7-15, 7-17 from the time when the pulse shown in the figure is generated, that is, from the time when the correction voltage is generated, so that the pulse is delayed from a certain delay time. On the other hand, the variable delay line 7-16, 7-
17 goes in the opposite direction and is output. No. 8-12
The figure shows the output of variable delay line 7-15,
Figure 13 shows the outputs of the variable delay lines 7-18, and when the correction voltage 3 is not generated, the time between t ₁₀₂ and t ₁₀₂ ′ or the time between t ₁₀₃ and t ₁₀₃ ′ is delayed by a certain amount. Corresponding to time τ ₁₂ , pulse 10
a (hereinafter referred to as correction pulse) is delayed from time t ₁₀₄ ' because of correction voltage 3, and time t ₁₀₉ ' is delayed from t ₁₂₄
This shows that the progress has been made up to the point in time. The reason why two sets of variable delay lines are provided here is that it is necessary to consider whether to advance or delay the correction pulse at both the rising and falling points of the signal. The time is selected to be approximately equal to or shorter than the signal pulse width time that requires correction, ie, t ₁₀₃ and t ₁₀₄ . The pulse generator 7-43 generates pulses at both the rising and falling points _t105 and _t121 of the output pulse of the OR circuit 7-28, and the delay time is variable on the delay line 7-15...
...The signal that has passed through the delay line 7-44, which has a delay time approximately equal to the constant delay time τ ₁₂ of 7-18, is sampled by the sampling circuit 7-45, and t is calculated from the sample voltage at times t ₁₀₅ and t ₁₂₁ . The correction pulses at ₁₂₃ and t ₁₂₄ will determine whether the change in the signal occurs at a rising or falling point. This output is formed by a shaping circuit 7-46, for example, a Schmitt circuit, and then sent to an AND circuit 7-30, 7-
32 and an inverter 7-47, and is input to each AND circuit 7-29, 7-31. If the correction signal corresponds to the rising edge of the signal from the combination of each AND circuit 7-29...7-32 and each variable delay line 7-15...7-18, each AND circuit
If the circuits 7-30 and 7-32 operate and correspond to the falling point, each AND circuit 7-29 and 7-3
1 is the one that operates, and the AND circuit 7 in this example
-30 and the outputs of AND circuits 7-32 respectively to the 8th
Shown in Figure-12 and Figure 8-13.

The output of each AND circuit 7-29, 7-30 passes through an inverter 7-39, 7-34, respectively, to an OR circuit 7.
-37, mixed by flip-flop 7-
It is input to the set terminal No. 39. On the other hand, the outputs of the AND circuits 7-31 and 7-32 are output from the inverter 7-31, 7-32.
35, 7-36 to the OR circuit 7-38, and this output is also applied to the flip-flop 7-3.
Input to the reset terminal of 9. The waveform of the Q output of flip-flop 7-39 is illustrated in FIGS. 8-14. The OR circuit 7-48 makes use of pulses at each of the rising and falling points of the signal, and the pulses are ANDed.
The sampling operation described below is performed satisfactorily by the sampling pulse generator 7-55 via the circuit 7-49 and the OR circuit 7-52, and the sampling pulse becomes a sufficiently narrow width compared to the correction pulse width. It is input to the sampling pulse input terminal 51. By the output of the inverter 7-50 connected to the output of the OR circuit 7-28,
The output of the AND circuit 7-49 is blocked at the time when the correction pulse is generated, and the output of the OR circuit 7-40 is blocked at the time when the correction pulse is generated.
53, is inputted via the OR circuit 7-52, and thus the output of the sampling circuit 7-51 is the 8-1
The waveform shown in Figure 5 will be output. Note that the delay line 7-54 has a delay time approximately equal to the width of the sampling pulse, so that the sampling pulse generated at time _t108 holds the voltage corresponding to _E104 , and at time _t124 .
8-15 shows the output of the 7-51 sampling circuit. The output of the 7-51 sampling circuit is input to the 7-41 variable amplifier and the 8-1
5. The gain changes depending on the signal shown in Figure 5, i.e., if the signal is low, the gain changes so that the gain increases, and during the time when no correction is required, the amplification is constant, so the 7-56 output terminal has the 8- The corrected recording signal voltage shown in FIG. 16 is obtained. In addition,
The 7-40 delay line is for correcting a time delay corresponding to the pulse width of the sampling pulse.

In the above explanation, silver halide film was used as an example of a recording medium, and its characteristics were assumed to be that the density has a linear relationship with the exposure amount, but generally speaking, this assumption holds true only when the recording medium is This is a case where the recorded density change amount is limited to a very small part of the recordable density range.

Next, we will explain the correction in the case where the linear relationship described above is not satisfied and, as an extreme case, there is a binary change in density D _nio12 when the exposure amount is below a certain threshold value and D _nax12 when it is above the threshold value. (Hereinafter, the corrections shown in figures 7 and 8 will be referred to as the first corrections 11 and 1.
The correction shown in FIG. 2 is referred to as a second correction. ).

FIG. 9-1 shows an example of the recording signal voltage subjected to the first correction, and FIG. 9-2 shows the amount of exposure given to the recording medium. In addition, FIG. 9-1 corresponds to FIG. 6-4, FIG. 9-2 corresponds to FIG. 6-3, and the relationship of the horizontal axis etc. in FIG. 9 is the same as that of FIG. 6. Now, the recording medium, in this example a silver halide film, is exposed at the 9th level of the exposure amount.
Assuming that there is a threshold value at P ₁₂₁ shown in Figure 2, and the density becomes D _nax12 for an exposure amount greater than P ₁₂₁ , and D _nio121 for an exposure amount below P ₁₂₁ , the recorded pattern obtained in this case is The result is as shown in Figure 9-3.

As is clear from FIG. 9-3, unlike the recording pattern of FIG. 6-1, it is clear that errors such as l ₁₂₁ and l ₁₂₂ occur.

FIG. 10 shows a case where the second correction in such a case is added to the recording signal voltage after the first correction, and FIG. 10-1 shows a desirable recording pattern (same as FIG. 6-1). As shown in Figure 10-2,
The amount of exposure to the recording medium due to the first corrected recording signal voltage (FIG. 9-2 and the same figure) is illustrated, and the 10th
FIG. 9-3 shows a recording pattern (same as FIG. 9-3) on a recording medium when the exposure threshold value is _P131 . 1st
The error lengths in the diagram 0-3 are indicated by l ₁₂₁ and l ₁₂₂ .

The second correction in this case can be considered as follows. In other words, the time point at which the recording signal voltage is changed can be corrected by advancing or delaying the error length l on the recording pattern by l/V in relation to the moving speed V of the recording medium. , as shown in Figure 10-5, the delay and the second correction may be performed for each time τ ₁₃₁ =l ₁₂₁ /V and τ ₁₃₂ =l ₁₂₂ /V, respectively. For reference, the recording signal voltage without the second correction is shown in FIG. 10-4. Note that the times τ ₁₃₁ and τ ₁₃₂ are determined if the slope at the time of the change in the exposure amount and the threshold value of the exposure amount are given.

Fig. 10-6 shows the temporal change in the exposure amount due to the second corrected recording signal voltage (shown in Fig. 10-4), and Fig. 10-7 shows the case where the exposure amount threshold P ₁₃₁ exists. This shows the recording pattern in the second
It is clear that the correction is effective. In this case, since there is a threshold value for the exposure amount, the 10th
The disturbance in Figure 6 136 is not a problem.

Next, the second correction method is specifically shown in FIG. Note that in FIG. 11, functional blocks that overlap with those in FIG. 7 are indicated by the same numbers as in FIG.

Here, 11-1 is a variable delay line, 11
-2 is a stretcher which has the function of maintaining the voltage at the end of the correction voltage of the input signal (shown in Figure 8-8) for a certain period of time; for example, by using an A/D converter to shift the voltage data at the point in time. This data is stored in a register or the like, outputted by a D/A converter, held, and reset after a certain period of time.

Reference numeral 11-3 is an output terminal for the recording signal voltage subjected to the first and second corrections. The Q output of flip-flop 7-39 shown in FIG. 7 is illustrated for convenience in the following explanation in FIG. 12-1. The output of the OR circuit 7-37 is input to the variable delay line 11-1, and the delay times τ ₁₄₁ and τ ₁₄₂ are set in advance in relation to the moving speed of the exposure threshold recording and the diameter of the light spot. Output with a delay. where τ ₁₄₁
(τ ₁₄₁ = 2τ ₁₃₁ ) is the delay time during the time when the correction voltage is not generated, and the delay time during the time when the correction voltage is generated because the slope of the exposure amount changes as shown in Figure 10-2. The time is changed in relation to the correction voltage and is τ _142. If τ ₁₄₂ = τ ₁₃₂ , then _the interval between each pulse will change, so the value is corrected by this amount.

The output of variable delay line 11-1 is input to the set input of flip-flop 7-39, while
The output of OR circuit 7-38 (first
2-3) is input, and the flip-flop 7-
A signal as shown in FIG. 12-4 is obtained at the Q output of 39. On the other hand, the output of the sampling circuit 7-51 passes through the stretcher 11-2 and becomes the waveform shown in Figure 12-5. Although it ends at time _t124 , it is stretched to time _t151 by the action of stretcher 11-2. The amplitude of the output of the variable amplification factor amplifier 7-41 is controlled by the output of the stretcher 11-2 (shown in Fig. 12-5) in the same manner as explained in Fig. The second corrected recording signal voltage, ie, the drive signal voltage, is output to the output terminal 11-3.

In the above detailed explanation of the present invention, it is assumed that the light intensity distribution of the light spot is uniform, but the gist of the present invention can be applied even when the light intensity distribution is a Gaussian distribution, for example. Needless to say, the present invention can also be applied to a rectangular spot instead of a circular spot. Further, although a silver salt film is used as an example of the recording material, it is obvious that this can also be applied to other recording materials such as photosensitive resin (photoresist).

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to apply an optimal drive signal to the optical modulator when recording a signal on a recording medium whose recording state has a threshold value with respect to the exposure amount. , the effects of the present invention are tremendous.

[Brief explanation of the drawing]

Figure 1 shows the principle of optical recording. Figure 2-1 is the first
Fig. 2-2 is an explanatory diagram showing the exposure amount at each point on the recording medium, Fig. 2-3 is an enlarged perspective view of the main part in the figure.
The figure is an explanatory diagram of the drive signal voltage applied to the modulator. Fig. 3-1 is an explanatory diagram showing the drive signal voltage applied to the modulator, Fig. 3-2 is an explanatory diagram showing the beam radiation intensity, and Fig. 3-3 is an explanatory diagram showing the exposure amount at each point on the recording medium. Explanatory diagrams, FIGS. 3-4 are explanatory diagrams showing the recording density of the recording medium. FIG. 4-1 is an explanatory diagram showing the drive signal applied to the modulator, and FIG. 4-2 is an explanatory diagram showing the amount of exposure to the recording medium. FIG. 4-3 is an explanatory diagram showing the recording density of the recording medium. 5th-
Fig. 1 is an explanatory diagram showing the ideal recording density on the recording medium, Fig. 5-2 is an explanatory diagram showing the achievable recording pattern on the recording medium, and Fig. 5-3 is an explanatory diagram showing the ideal recording density on the recording medium.
FIG. 3 is an explanatory diagram showing a drive signal voltage waveform for obtaining the recording pattern shown in the figure. Figure 6-1 is a pattern density waveform diagram on the recording medium, Figure 6-2,
Figure -6 is a reproduction output voltage waveform diagram obtained from the recording medium, Figures 6-3 and 6-5 are density waveform diagrams on the recording body, and Figure 6-4 is the density shown in Figure 6-3. A drive signal voltage waveform diagram for obtaining a waveform, FIG. 6-7 is an enlarged view of the main part of FIG. 6-4, and FIG. 6-8 is an enlarged view of the main part of FIG. 6-3. FIG. 7 is a block diagram showing a signal recording method according to the present invention. Figures 8-1 to 8-16 are for explaining the operation of Figure 7.
Waveform diagram of each point shown. Figure 9-1 is a drive signal voltage waveform diagram, Figure 9-2 is an explanatory diagram showing the exposure amount, and Figure 9-2 is an explanatory diagram showing the exposure amount.
Figure 3 is a waveform diagram showing the recording density on the recording medium. Figure 10-1 is a density waveform diagram on the recording medium, Figure 10-2 is an exposure waveform diagram, and Figure 10-3 is a diagram of the exposure amount waveform.
The figure is a density waveform diagram on the recording medium, Figure 10-4 is a drive signal voltage waveform diagram after the first correction, and Figure 10-4 is a diagram of the drive signal voltage waveform after the first correction.
Figure-5 is a drive signal voltage waveform diagram with the first and second corrections, Figure 10-6 is an exposure waveform diagram, and Figure 10-7 is a diagram of the exposure amount waveform.
The figure is a concentration waveform diagram. FIG. 11 is a block diagram showing a signal recording method for applying the second correction. 12-1 to 12-6 are signal waveform diagrams at each part shown in FIG. 11. Here, 7-15, 7-16, 7-17, 7-
18, 11-1 is a variable delay line, 7-4
4, 7-42, 7-54 are day line, 7-
3, 7-8 are triangular wave generators, 7-4, 7-9, 7
-45, 7-51 is a sampling circuit, 7-5,
7-10, 7-55 are sampling pulse generators, 7-23, 7-27, 7-39 are flip-flops, and 7-41 is a variable gain amplifier.

Claims (1)

[Scope of Claims] 1. By condensing a light beam whose light intensity is modulated in accordance with a recording pulse signal into a spot, and scanning a recording medium whose recording state has a threshold value with respect to the exposure amount with this light spot, In a signal recording method that forms a binary recording pattern on a recording medium, the timing of the change in the recording pulse signal is adjusted so that the recording pattern actually formed on the recording medium is equal to the pattern of the recording pulse signal. In order to account for the error in the time when the exposure amount of the recording medium reaches the threshold value earlier or later, a correction is made in advance to delay or advance the time point at which the recording pulse signal changes, respectively, and with this corrected signal, the light of the light spot is A signal recording method characterized by modulating intensity.