JP2611954B2 - Optical disk recording device - Google Patents

Description

The present invention relates to an optical disk recording device.

[Conventional technology]

2. Description of the Related Art Conventionally, in a recordable optical disk device, in order to improve a recording density, a difference in recording pit length is recorded as information, such as recording a pit on an optical disk by a group coating signal. In order to record such pits, for example, in a compact disk, an EFM signal which is a kind of such a modulation method is used.

The EFM signal is modulated using nine types of pulse widths and pulse intervals with the clock period T as one unit length. The longest pulse has a length of 11T and the shortest pulse has a length of 3T. Having

[Problems to be solved by the invention]

In this case, a correct pit length and a constant pit width are required. As is well known, a shorter pit requires a relatively high recording energy density, and a long pit may have a relatively low recording energy density. That is, the length of the pit does not have a linear relationship with the length of the recording waveform, and the recording signal (for example,
When the EFM signal) is used as a write signal (cutting signal), there is a disadvantage that the shorter the pit, the shorter its length becomes than a predetermined value. In addition, the longer the pit, the higher the recording energy density at the end of the pit, so that a pit with a constant pit width cannot be obtained. Further, in order to change the recording energy density according to the length of the pulse of the recording signal, there is a disadvantage that a complicated control and circuit for controlling the output power of the optical recording beam are required.

Also, in order to improve the shape of the pit,
The EFM pulse signals of 3T, 4T,... 11T of the EFM signal are narrowed down by 1T to obtain recording signals of 2T, 3T,. In this case, the short pits may be even shorter.

The present invention has been made to solve such a problem.

[Means for solving the problem]

The recording apparatus for an optical disk according to the present invention comprises: means for obtaining a recording signal composed of pulses having a plurality of types of lengths; a plurality of types of pulse trains having different pulse widths; and detecting the length of each pulse of the recording signal. Means for obtaining a signal, means for outputting a pulse train having a pulse width corresponding to the pulse length of the recording signal based on the detection signal as a write signal, and optical recording with a constant output power based on the write signal Means for irradiating a beam.

Further, the recording apparatus of the optical disk of the present invention, a recording signal comprising a pulse having a plurality of types of lengths, and a means for obtaining a detection signal for detecting the length of each pulse of the recording signal,
Means for obtaining a plurality of types of pulse trains having different pulse widths, means for outputting a pulse train having a pulse width corresponding to the pulse length of the recording signal based on the detection signal as a write signal, and Means for irradiating an optical recording beam having a constant output power, wherein the pulse train having the widest pulse width is used as the write signal when at least the pulse length of the recording signal is shortest. It is.

[Action]

Since the present invention has the above configuration, a detection signal is obtained by detecting the length of the pulse of the recording signal, and based on the detection signal, the pulse of the recording signal is extracted from a plurality of types of pulse trains having different pulse widths. A pulse train having a pulse width corresponding to the length is output as a write signal, and pits are recorded using an optical recording beam having a constant output power based on the write signal, without changing the output power of the optical recording beam. Since the recording energy density can be set according to the pulse length of the recording signal, a good optical recording beam can be obtained. Further, each pulse width of the recording signal is measured until the next write signal arrives, and the necessary measurement can be completed before the delayed signal obtained by delaying the recording signal. The delayed delay signal and the write signal can be output in real time.

〔Example〕

 FIG. 1 is a block diagram showing one embodiment of the present invention.

In the figure, a reference signal 1 having a frequency 2f is applied to an EFM signal generator 2 and an inverting circuit 4 and is also applied to a half frequency dividing circuit 3 to obtain a frequency f (4.3218 MHz) and a period T.
(231 ns). The EFM signal c is applied to one input terminal of the AND circuit 15 and is sequentially delayed by delay circuits 5, 6, 7, and 8 having delay amounts of 2T, 0.5T, 1.5T, and 1T, and 2T, 2.5T, The delay signals d, j, m and p are delayed by 4T and 5T. The delay signal d is applied to the other input terminal of the AND circuit 15 and one input terminal of the AND circuit 18, and the delay signal j is applied to the other input terminal of the AND circuit 18 via the inverting circuit 17. The delay signals p and m are applied to each input terminal of the AND circuit 9, and the output terminal of the AND circuit 9 is applied to one input terminal of the AND circuit 10. The output of the inverting circuit 4 is applied to one input terminal of the AND circuits 13 and 14, and the clock signal b is applied to the other input terminals of the AND circuits 14 and 13 directly and via the inverting circuit 12, respectively. It is applied to the generator 2. Outputs of the AND circuits 13 and 15 are applied to respective input terminals of the AND circuit 16. The output of the AND circuit 14 is applied to the input terminal 24a of the switching circuit 24 as the narrowest first cutting output, and to one of the input terminals of the OR circuits 21 and 22, and further to the delay circuits 19 and 20. Are converted into delay signals s and t, and are applied to the other input terminals of the OR circuits 21 and 22. The outputs of the OR circuits 21 and 22 become the second and third cutting outputs having the intermediate width and the widest width, respectively, and are applied to the input terminals 24b and 24c of the switching circuit 24. The input terminals 24a, 24b and 24c of the switching circuit 24 are
Output terminal 24d via switches 24f, 24g and 24h respectively
And is connected to the other input terminal of the AND circuit 10. The outputs of the AND circuits 16 and 18 are respectively counting pulses h
And a clear pulse k are applied to the clock terminal and the clear terminal of the counter 23, respectively. The output of the counter 23 becomes a control output to control the switches 24f, 24g, and 24h to be turned on and off. The output of the AND circuit 10 is output to an output terminal 11 as an EFM cutting signal z.

The operation of the above configuration will be described in detail below with reference to the waveform diagram of FIG. In FIG. 2, the waveform charts denoted by reference numerals a to z show the waveforms appearing at the portions denoted by the same reference numerals in FIG.

The leading edge of the pits c ₁ , c ₂ ,... Of the EFM signal c is the reference signal a.
And the rising edge of the first clock signal b. The EFM signal c and the EFM signal c are
When an AND circuit with the delay signal d delayed by T is obtained by the AND circuit 15, the first half of the pits c ₁ and c ₂ of the EFM signal c has a width of 2T.
Is obtained. Since the pulse widths of the pit portions c ₁ and c ₂ of the EFM signal c can take nine different lengths of 3T, 4T,... 11T, the shortening pulses e ₁ and e, which are the high-level portions of the shortening signal e, ₂ also has nine lengths of 1T, 2T,... 9T.

On the other hand, a logical product of the inverted signal of the reference signal a and the first clock signal b and the AND circuit 13 are used to obtain the second clock signal g which becomes high during the low level period of the reference signal a and the first clock signal b. generate. AND circuit
At 16, the logical product of the second clock signal g and the shortened signal e is obtained to obtain a count pulse h indicating the length of the shortened pulses e ₁ and e ₂ by the number of the second clock signals.

Further, the inverted signal of the delayed signal j and the delay signal d, the AND circuit 18 generates a clear pulse k of width 0.5T immediately after the rise of the shortened pulse e _1.

The counter 23 counts the count pulse h ₁ immediately after the clear pulse k ₁ until the next clear pulse k ₂ , counts the pulse width of the shortened pulse e ₁ , generates a control signal, and controls the control terminal 24 of the switching circuit 24.
The switches 24f, 24g and 24h are turned on / off in addition to j. In order to obtain an EFM cutting signal having an intensity corresponding to the pulse width of the shortened pulses e ₁ , e ₂ ,... Is selected in accordance with.

The AND circuit 14 outputs 1 for each pulse of the first clock signal b.
The first cutting signal having the narrowest width at the ratio of ケ is obtained. The first cutting signal is delayed by delay circuits 19 and 20 to obtain delayed signals s and t, and the logical sum of these signals and the first cutting signal r is obtained by OR circuits 21 and 22 to have a medium width. The second cutting signal u and the widest third cutting signal v are obtained.

These first, second and third cutting signals r, u and v
Is selected according to the count output data applied to the control terminal 24j, and is output to the output terminal 24d. Now, when the pulse width of the pulse c ₁ of the EFM signal c is at 3T, the pulse width of the pulse e ₁ of shortening signal e count output of 1T becomes, thus the counter 23 is 1. Then, the switching circuit 24 is controlled so that only the switch 24h is turned on, and thereafter the widest third cutting signal v is applied to the AND circuit 10. Similarly,
If the pulse width of the EFM signal c is 4T, the pulse width of the shortened signal e is 2T. In this case, the second cutting signal u having a medium width is applied to the AND circuit 10. If the pulse width of the EFM signal c is 5T or more, the pulse width of the shortened signal e becomes 3T or more. In this case, the narrowest first cutting signal r is applied to the AND circuit.

In Figure 2 the pulse interval after the EFM pulse c ₁ is the lowest as the 3T, even if the after 5T pulse arrives,
By the same operation as described above, shortening the pulse e ₂ is obtained in the width 3T, counting pulses h of the result 3 Ke is withdrawn, it determined that the pulse length is 5. This measurement just before the 5T pulse p ₂ at 5T delayed signal p, so complete, it is possible to set the correct minimum width the pulse width of the EFM cutting signal z to turn on the switch 24f. Although not completed measurements the appropriate immediately preceding pulse p ₂ of the 5T delayed signal p If pulse longer than 5T pulse arrives as a pulse C ₂ of the EFM signal c, because the decision can be at least 5T pulse , The pulse width of the EFM cutting signal z may be the same as that of the pulse p ₂ of the 5T delay signal p,
The switch 24f may be turned on.

The cutting signal sequence w obtained by selecting in this way is
The signal is gated by the gate signal q and led out to the output terminal 8.

The gate signal q has a pulse width of 2T, 3T,... 10T in accordance with the pulse width of the pit portion of the EFM signal c, 3T, 4T,. Therefore, the AND circuit 10 assigns the two widest pulses to the pulse width 3T among the pulses of the EFM signal c from the cutting signal train w, and the middle pulse to the pulse width 4T. Approximately three pulses are allocated, and for a pulse width of 5T to 11T, the narrowest pulse of 4 to 10 pulses is allocated. In this way, the shorter the pulse, the higher the recording energy density becomes as the EFM cutting signal z, which is led out to the output terminal 11 and can be recorded with an accurate pit length.

As described above, it is possible to determine the pulse width of the second and third cutting signal by the delay time D ₁ and D ₂ of the delay circuit 19 and 20, the value of the linear velocity of the recording light beam diameter and the recording disk An optimum value may be determined according to the condition. For example, when the recording light beam diameter is 1 μ, the linear velocities are 1.2 m and 1.4 m.
The delay time D ₁ and D ₂ with respect to is as follows.

In the above example, the clear pulse k is made from the delay signals d and j. However, it can be made by differentiating the leading edge of the positive pulse of the delay signal d.

The shortened signal e is obtained by shortening each pulse of the EFM signal c by 2T, but is not limited thereto.
3T may be shortened by delaying 3T. In this case, the pulse width of the shortened signal with respect to the shortest 3T width EFM signal is zero, the 4T width is 1T, the 5T width is 2T, and the pulse width detection result by the counter 23 is also a 3T, 4T, 5T width pulse of the EFM signal. Since the counting results of 0, 1, and 2 are obtained, the switches 24f, 24g, and 24g correspond to these counting results, respectively.
Just turn on h.

〔The invention's effect〕

As described above, according to the present invention, a pulse train having a pulse width corresponding to the pulse width of a recording signal is used as a write signal, and pits are recorded with an optical recording beam having a constant output power. The pits can be recorded accurately without the need for complicated control and circuits for control.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a waveform diagram of each part for explaining the operation thereof. 5, 6, 7, 8, 19, 20 delay circuit 23 counter 24 switching circuit

Claims (2)

(57) [Claims] A means for obtaining a recording signal comprising pulses having a plurality of types of lengths; a plurality of types of pulse trains having different pulse widths; and means for obtaining a detection signal for detecting the length of each pulse of the recording signal. Means for outputting, as a write signal, a pulse train having a pulse width corresponding to the pulse length of the recording signal based on the detection signal, and means for irradiating an optical recording beam having a constant output power based on the write signal A recording device for an optical disk, comprising: 2. A recording signal comprising pulses having a plurality of types of lengths, means for obtaining a detection signal for detecting the length of each pulse of the recording signal, and means for obtaining a plurality of types of pulse trains having different pulse widths. Means for outputting, as a write signal, a pulse train having a pulse width corresponding to the pulse length of the recording signal based on the detection signal, and means for irradiating an optical recording beam having a constant output power based on the write signal A recording apparatus for an optical disk, wherein the pulse train having the widest pulse width is used as the write signal when at least the pulse length of the recording signal is the shortest.