JPH03183025A - Optical disk device - Google Patents

Abstract

PURPOSE:To obtain an optical disk device with high recording density by providing a recording circuit, a reproducing circuit, a reference waveform generating circuit and a recording waveform control circuit. CONSTITUTION:In a variable recording waveform generating circuit 1, a train with pulse width corresponding to recorded data is outputted by a pulsing circuit 7, and a recording waveform is generated through a delay element 8, a multiplier 9 and an adder 10. A recording circuit 2 makes a recording pit onto a recording medium 3. It is transmitted from a reproducing circuit 4 to a timing detection circuit 16 of a reference waveform generating circuit 6 and the recorded data are taken out from a data buffer 14 synchronously with a reproducing signal. Further, the waveform of the data is shaped by a filter 15 and a reference waveform is obtained. In a recording waveform control circuit 5, the reference waveform is delayed 8 and difference from the reproducing signal is calculated by an adder 13. Then, the difference and the delayed reference waveform are multiplied 12 and added to an integration value set by an integration circuit 11 in advance. An integration period is controlled by the timing detection circuit 16 and a reproducing waveform is applied so as to be extremely similar to the reference waveform. Thus, when the recording waveform is compensated by such a feedback system, optimum recording power and waveform can be obtained and high recording density can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical disc device that records and reproduces information using optical signals.

(Prior Art) The configuration of a conventional optical disc recording device is shown in FIG. The encoded input data example is converted by the pulse generator 7 into a rectangular pulse train having a constant amplitude and pulse width. This rectangular pulse train is input to the recording circuit 2, where it is converted into power-modulated laser light, and pits are recorded on the recording medium 3.

(Problems to be Solved by the Invention) When recording information on an optical disc medium, if the power of the irradiated light is high, the pits recorded on the disc will become large, making it impossible to obtain a high recording density. On the other hand, if the recording power is low, it becomes impossible to obtain a sufficient reproduction signal for reproducing information. Therefore, there is an optimum recording power for obtaining high recording density. Further, even if the recording density is the same, when recording is performed using the optimum recording power, the recording/reproducing margin is improved.

In an optical disk device with a conventional configuration, the optimum recording power and
There is no means to compensate for the effects of changes in recording waveforms. Therefore, this variation appears in the reproduced signal as a difference in the thickness and shape of the recording pits, and has become an obstacle to obtaining high recording density. In addition, when the recording output power is changed using a military-style rectangular pulse waveform, the recorded bit shape is distorted due to the influence of heat flow on the recording medium, and as a result, distortion also appears in the reproduced waveform. There was also a drawback.

The object of the present invention is to eliminate such conventional drawbacks, to provide an optical disc that can obtain high recording density by always maintaining conditions for forming standard pits, and by optimizing recording power and recording waveform. The goal is to provide equipment.

(Means for Solving the Problems) An optical disc device of the present invention is an optical disc device that records information on a recording medium using a light beam, and receives an information data string and a recording waveform control signal as input, and receives the information data string and a recording waveform control signal as input. a recording waveform generation circuit that outputs a signal having a waveform set by the recording waveform control signal based on the recording waveform control signal; and an output signal of the recording waveform generation circuit as input; a recording circuit for recording an information data string; a reproducing circuit for reproducing the information data string recorded on the recording medium and outputting a reproduction signal; and a reproduction circuit for reproducing the information data string and the reproduction signal output from the reproduction circuit. As input,
a reference waveform generation circuit that outputs a reference reproduction signal having an ideal reproduction signal waveform in synchronization with the reproduction signal; a reproduction signal output from the reproduction circuit; and a reference reproduction signal output from the reference waveform generation circuit. The present invention is characterized in that it has the recording waveform control circuit which takes as an input and outputs a recording waveform control signal to the recording waveform generation circuit so that the surface input waveforms match.

As the recording waveform generating circuit, a circuit including a pulsing circuit and an adaptive transversal filter connected in a cascade can be used.

As the recording waveform generation circuit, an arbitrary waveform generation circuit that can set the amplitude of the output waveform at a specific time can be used.

Note that the arbitrary waveform generation circuit includes a circuit that can independently set the rising and falling parts of the recording waveform, and a circuit that can independently set the recording waveform for each recording pattern classified according to the values of previous and subsequent recording data. There is.

(Operation) In the present invention, information is recorded on a medium using a recording signal generated by a recording waveform generating circuit whose generated waveform is variable.

Next, by generating the information recorded in this way and comparing it with a reference reproduction signal given as an ideal reproduction waveform, the recording waveform generation circuit generates a recording waveform so as to reduce the difference between the two. Adjust. By performing this recording, reproduction, and adjustment cycle one or more times, the recording conditions are improved and the recording pit approaches an ideal shape.

By using this method, it is possible to record under different recording conditions for each recording medium or recording track on the recording medium.
A recording power output waveform that can always form constant bits can be obtained.

(Example) Next, the present invention will be described in detail with reference to FIGS. 1 to 4.

FIG. 1 is a block diagram showing one embodiment. FIG. 2 shows the output waveforms of each part of the block diagram. The encoded recording data is sent to a recording waveform generation circuit 1 whose generated waveform is variable. In the recording waveform generation circuit, first, a pulse generator 7 outputs a pulse train having a pulse width I according to recording data. An example of the output waveform of the pulsing circuit is shown in FIG. The pulsed recording data passes through a transversal filter constituted by a delay element 8 with a delay time I, a multiplier 9, and an adder 10, and a recording waveform is output.

The recording waveform changes depending on the magnitude of the voltage applied to the magnification control terminal of the multiplier 9. The recording waveform outputted here is sent to the recording circuit 2, and recording pits are formed on the recording medium 3 by modulating the power of the recording beam with the recording waveform. As the recording circuit, a circuit similar to the conventional circuit can be used, so a detailed explanation will be omitted. FIG. 2 shows the shape of a recording pit when recording is performed using the recording waveform as described above. The shape of the recording pit changes depending on the strength of the recording power, and this also affects the resulting reproduced shape as a change in waveform.

Next, using the recording waveform determined as the initial setting, a reproduced waveform is extracted by the reproducing circuit 4 from the recording medium recorded as described above. This reproducing circuit can also be a circuit similar to the conventional one. Further, an optical head having a plurality of light beams for recording and reproduction may be used so that recording and reproduction can be performed almost simultaneously. By using such an optical head, optimization of recording waveforms as described below can be performed at higher speed.

First, a reproduction signal is sent from the reproduction circuit 4 to the timing detection circuit 16 of the reference waveform generation circuit 6.
The same data that was used during recording is extracted from the recorder in synchronization with the reproduction signal.

Further, the extracted data is passed through a waveform shaping filter 15 and output as a reference waveform. This reference waveform provides an ideal reproduction waveform for recorded data, and is obtained by applying linear or non-linear filtering such as a Gaussian filter or short pulse generation. Further, the amplitude of the reference waveform at this time can be determined, for example, so that its average value matches the average value of the reproduced waveform, or so that the amplitude always takes a constant value. The reproduction waveform actually extracted by the reproduction circuit 4 is controlled by the recording waveform control circuit 5 to adjust the recording waveform so that it becomes a signal closer to the reference waveform.

The reference waveform obtained as an output from the reference waveform generation circuit 6 is delayed by the delay circuit 8, and then the difference from the reproduced signal is extracted by the adder 13. The difference signal is shown as the error signal waveform in FIG. In order to make the error signal approach O, the product of the error signal and the reference waveform delayed by the delay circuit 8 is extracted by the multiplier 12, and further, the integration circuit 11 controls the recording waveform set in advance. The integral value of the output signal of each multiplier is added to the voltage. The integration period of the integration circuit is controlled by the timing detection circuit 16, and integration is performed only while the reproduced waveform and reference waveform are being obtained.

In order to stably obtain a recording waveform, it is desirable that the amount of change in the output voltage of the integrating circuit at one time is small. In this way,
According to the newly set output of the integrating circuit, a new recording waveform as shown in the adjusted recording waveform of FIG. 2 is obtained. This recorded waveform is different from the first recorded waveform.
Provides a reproduced waveform that is closer to the reference waveform.

By performing a series of pulse waveform adjustments by recording and reproducing as described above one or more times, the data recording conditions are gradually improved.

In addition, this recording waveform adjustment may be performed by recording and reproducing using a specific single or multiple tracks when the recording medium is replaced, or by adjusting a part of the target track or It is conceivable that all of them are used, or that both of the above are used in combination. Furthermore, a similar circuit can be used when recording multivalued information. It is clear that at this time as well, the error in recording information can be reduced by optimally selecting the recording power and recording waveform.

Furthermore, since the recording waveform is important at the rising edge and falling edge of the recording data, there is also a method of setting only the recording waveform particularly around these edges. FIG. 3 shows an example using this method. Here, we have shown one constructed using a digital circuit. The recording waveform generation circuit 1 is constituted by an arbitrary waveform generation circuit using a multiplexer 20 and a D/A converter 21. The recording waveform is set as a numerical value of an up/down counter 22 (hereinafter referred to as a U/D counter) in which either count up or count down can be selected by an external control terminal. In Figure 3,
A case is shown in which three U/D counter improvement stages are used for recording data no. 11, and the lower three stages are used for recording data "1".

Next, the operation of the circuit will be explained. The counter 19 of the recording waveform generation circuit 1 is reset to O by the reset signal given by the exclusive 0R18, and then counts up in clock cycle I, and when it counts up to 2, it continues counting up until the next reset signal is input. Stop counting. The reset signal is generated by D, the flip-flop 17 and the exclusive 0R18, so that the recording data is
The multiplexer 20 selects the upper stage or lower stage of the U/D counter according to the recording data "°O" and "1"', and further outputs the output of the counter. Depending on O~2, the 1st~3rd U/
Select and output the value of the D counter. The numerical value output by the multiplexer is output by the D/A converter 21 as a recording waveform.

The operations of the recording circuit 2, recording medium 3, reproduction circuit 4, and reference waveform generation circuit 6 are similar to those of the circuit shown in FIG. The recording waveform control circuit 5 inputs the reproduced waveform extracted by the reproduction circuit and the reference waveform, and the adder 13 first extracts the error signal waveform.

The error signal is converted into a binary digital signal by a comparator 24 depending on whether the signal is positive or negative. This signal has a delay time I
The data is delayed by the delay circuit 8, and the exclusive OR with the recording data output by the data buffer 14 is output at exclusive 0R18. This output corresponds to the product of recorded data and error signal. The U/D counter 22 is switched between count-up and count-down by this binary signal. The counter operating at this time is switched between an upper stage and a lower stage according to the recording data "Qlt, R1", and counts in synchronization with the reproduction signal. The new U/D counter value obtained thereby provides the next recording waveform.

In the above circuit configuration, the counter 19 starts counting from the time when the recorded data changes, and at a predetermined count value,
Since the recording stops until the recording data changes next, only the recording waveforms of the rising and falling edges of the data are set. Furthermore, since the values of the U/D counters are independent in the upper and lower stages, there is an advantage that the rising recording waveform and the falling recording waveform can be controlled independently.

In addition, by providing the recording waveform generation circuit 1 and the recording waveform control circuit 5 with a recording data string identification function within several bits, it is possible to independently identify recording data patterns of approximately several bits.
You can also set the recording waveform. As a result, the optimum recording waveform can be set for various recording patterns in which differences in the optimum recording waveform are predicted due to the nonlinearity of heat flow. FIG. 4 shows a circuit configuration when recording waveforms are independently set for a data pattern of 3 bits of recording data. Since the basic circuit configuration is the same as the circuit shown in FIG. 3, only the circuit configurations of the recording waveform generation circuit 1 and the recording waveform control circuit 5 are shown here.

The recording waveform generating circuit 1 requires a counter 19 that counts up in clock cycle I, and a shift register 25 that outputs 3 bits of immediately previous recording data to a multiplexer. The multiplexer 20 selects a U/D counter group 26 made up of a plurality of U/D counters using the 3 bits output from the shift register, and further uses the value of the counter 19 to select the value of the selected U/D counter. The signal is sent to the D/A converter 21. As a result, the recording waveform corresponding to "Qll, ("1") is independently determined by a 3-bit data pattern including data before and after it.

The recording waveform control circuit 5 also receives the immediately preceding three bits of the recording data sent from the reference waveform generation circuit 6 to the decoder 27.
A shift register is provided for outputting to the output terminal. The decoder outputs a control signal for changing only the numerical value of the U/D counter group corresponding to the data pattern of the signal being reproduced among the plurality of U/D counter groups 26.

Thereby, the recording waveform for a predetermined data pattern is controlled completely independently from other recording waveforms.

(Effects of the Invention) According to the present invention, by compensating the recording waveform with a feedback system, it is possible to obtain the optimum recording power and recording waveform according to the characteristics of the recording circuit and recording medium, and to obtain a high recording density. becomes possible.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing one embodiment, FIG. 2 is an explanatory diagram showing operating waveforms of each part of the circuit in FIG. 1, FIGS. 3 and 4 are system diagrams showing another embodiment, and FIG. The figure is a system diagram for explaining the prior art. In the figure, 1... recording waveform generation circuit, 2... recording circuit, 3...
- Recording medium, 4... Reproduction circuit, 5... Recording waveform control circuit, 601. This is a reference waveform generation circuit.

Claims (1)

[Claims] (1) In an optical disk device that records information on a recording medium using a light beam, an information data string and a recording waveform control signal are input, and based on this information data string, the information set by the recording waveform control signal is a recording waveform generation circuit that outputs a signal having a waveform; a recording circuit that receives an output signal of the recording waveform generation circuit as an input and records the information data string on the recording medium based on the input signal; and the recording medium. A reproduction circuit that reproduces the information data string recorded on the top and outputs a reproduction signal, and inputs the information data string and the reproduction signal output from the reproduction circuit, synchronizes with the reproduction signal, and generates an ideal a reference waveform generation circuit that outputs a reference reproduction signal having a reproduced signal waveform, the reproduction signal output from the reproduction circuit and the reference reproduction signal output from the reference waveform generation circuit are input, and both input waveforms match. An optical disc device comprising: the recording waveform control circuit that outputs a recording waveform control signal to the recording waveform generating circuit.