JP2734701B2 - Optical disk drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical disk device for recording and reproducing information using an optical signal.

(Prior Art) FIG. 5 shows a configuration of a conventional optical disk recording apparatus.
The encoded input data example is converted into a rectangular pulse train having a constant amplitude and pulse width by the pulse conversion circuit 7. The rectangular pulse train is input to the recording circuit 2 to be converted into power-modulated laser light, and pits are recorded on the recording medium 3.

(Problems to be Solved by the Invention) When information is recorded on an optical disk medium, if the power of irradiation light is large, pits recorded on the disk become large, so that a high recording density cannot be obtained. On the other hand, if the recording power is low, it is not possible to obtain a sufficient reproduction signal for reproducing information. Therefore, there is an optimum recording power for obtaining a high recording density. In addition, even if the recording density is the same, when recording is performed with the optimum recording power, the recording / reproducing margin is improved.

The optical disk device having the conventional configuration does not have a means for compensating for the effect of the change in the optimum recording power and the recording waveform due to the variation in the characteristics of the recording circuit 2 and the recording medium 3. For this reason, this variation appears in the reproduced signal as a difference in the size and shape of the recording pit, which has been an obstacle to obtaining a high recording density. When the recording output power is changed using a simple rectangular pulse waveform, the recording pit shape is distorted due to the influence of heat flow on the recording medium, and as a result, distortion also appears in the reproduction waveform. There was also a disadvantage.

An object of the present invention is to eliminate such conventional drawbacks, maintain a condition for forming a standard pit at the root, and obtain a high recording density by obtaining an optimum recording power and a recording waveform. An optical disk device is provided.

(Means for Solving the Problems) An optical disc apparatus according to the present invention is an optical disc apparatus for recording information on a recording medium using a light beam. A recording waveform generation circuit that outputs a signal having a waveform set by the recording waveform control signal, and an output signal of the recording waveform generation circuit as an input. A recording circuit that records an information data sequence, a reproduction circuit that reproduces the information data sequence recorded on the recording medium and outputs a reproduction signal, and a reproduction circuit that outputs the information data sequence and the reproduction signal output from the reproduction circuit. A reference waveform generating circuit for inputting and outputting 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 the reference wave; The recording waveform control circuit receives the reference reproduction signal output from the shape generation circuit and outputs a recording waveform control signal to the recording waveform generation circuit so that both input waveforms match.

As the recording waveform generating circuit, a circuit composed of a cascade connection of a pulse generating circuit and an adaptive transversal filter can be used.

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

As the arbitrary waveform generating circuit, a circuit capable of independently setting a rising portion and a falling portion of a recording waveform, and a circuit capable of independently setting a recording waveform for each recording pattern classified by values of preceding and succeeding 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 capable of generating a variable waveform. Next, the information recorded in this way is generated and compared with a reference reproduction signal given as an ideal reproduction waveform, so that the difference between the two is reduced. To adjust. This recording, playback,
By performing the 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 obtain a recording power output waveform capable of always forming constant pits under different recording conditions for each recording medium or each recording track on the recording medium.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing one embodiment. FIG. 2 shows the output waveform of each part of the block diagram. The encoded recording data is supplied to a recording waveform generating circuit 1 having a variable generated waveform.
Sent to In the recording waveform generating circuit, first, a pulse train having a pulse width τ corresponding to the recording data is output by the pulsing circuit 7. An example of the output waveform of the pulsing circuit is shown in FIG.
Shown in the figure. The pulsed recording data passes through a transversal filter constituted by a delay element 8 having a delay time τ, a multiplier 9 and an adder 10 to output a recording waveform. The recording waveform changes according to the magnitude of the voltage applied to the magnification control terminal of the multiplier 9. The recording waveform output here is sent to the recording circuit 2, and the power of the recording beam is modulated by the recording waveform, so that recording pits are formed on the recording medium 3. As the recording circuit, a circuit similar to the conventional circuit can be used, and thus a detailed description is omitted. FIG. 2 shows the shape of the recording pit when recording is performed with the above-described recording waveform as the recording pit. The shape of the recording pit changes depending on the strength of the recording power, and also affects the obtained reproduction shape as a waveform change.

Next, using the recording waveform determined as the initial setting, the reproduction circuit 4 extracts a reproduction waveform from the recording medium recorded as described above. As this reproducing circuit, a circuit similar to the conventional circuit can be used. Further, an optical head having a plurality of light beams for recording and reproduction so that reproduction can be performed almost simultaneously with recording may be used. By using such an optical head, optimization of a recording waveform 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, and the same data as the data used for recording is extracted from the data buffer 14 in synchronization with the reproduction signal. Further, the extracted data is output as a reference waveform by passing through the waveform shaping filter 15. This reference waveform gives an ideal reproduced waveform to the recording data, and is obtained as a result of performing a linear or non-linear filtering such as a Gaussian filter or a short pulse. In addition, the amplitude of the reference waveform at this time can be determined, for example, such that the average value matches the average value of the reproduced waveform, or the amplitude always takes a constant value. The reproduction waveform actually taken out by the reproduction circuit 4 is controlled by the recording waveform control circuit 5 to adjust the recording waveform so as to be 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 reproduction signal is extracted by the adder 13. The difference signal is shown as the error signal waveform in FIG. The product of the error signal and the reference waveform delayed by the delay circuit 8 is taken out by the multiplier 12 so that the error signal approaches 0,
Further, the integration circuit 11 adds the integrated value of the output signal of each multiplier to the control voltage of the recording waveform set in advance. The integration period of the integration circuit is controlled by the timing detection circuit 16, and the integration is performed only while the reproduction waveform and the reference waveform are obtained. In order to obtain a stable recording waveform, it is desirable that the amount of change in the output voltage of the integration circuit at one time be small. In this way, a new recording waveform as shown in the post-adjustment recording waveform in FIG. 2 is obtained according to the newly set output of the integrating circuit. This recording waveform gives a reproduced waveform closer to the reference waveform than the initially set recording waveform.

By performing a series of pulse waveform adjustments by performing recording / reproduction as described above at least once, data recording conditions are gradually improved.

In addition, this recording waveform adjustment is performed by performing recording and reproduction using a specific single or a plurality of tracks when a recording medium is replaced, or a part of a target track before recording, or When using all of them, it is also conceivable to use both of them. A similar circuit can be used for recording multi-valued information.
At this time, it is apparent that the information recording error can be reduced by optimally selecting the recording power and the recording waveform.

Also, since the recording waveform is important at the rise and fall of the recording data, there is also a method of setting only the recording waveform in the vicinity thereof. FIG. 3 shows an embodiment according to this method. Here, a configuration constituted by a digital circuit is shown. The recording waveform generating circuit 1 is configured by an arbitrary waveform generating 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) which can select a count-up or a count-down by an external control terminal. FIG. 3 shows a case where three upper U / D counters are used corresponding to the recording data "0" and three lower U / D counters are used corresponding to the recording data "1".

Next, the operation of the circuit will be described. After the counter 19 of the recording waveform generating circuit 1 is reset to 0 by the reset signal given by the exclusive OR 18, it counts up in the clock cycle τ and counts up to 2 until the next reset signal is input. Stop counting. The reset signal is output at the time when the recording data changes between “0” and “1” by the D-flip-flop 17 and the exclusive OR 18. The multiplexer 20 selects the upper stage and the lower stage of the U / D counter according to “0” and “1” of the recording data, and further according to the output 0 to 2 of the counter, the first to third U / D counters therein. 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, the recording medium 3, the reproducing circuit 4, and the reference waveform generating circuit 6 are the same as those of the circuit of FIG. In the recording waveform control circuit 5, the reproduced waveform extracted by the reproducing circuit and the reference waveform are input, and the adder 13 first extracts the error signal waveform. The error signal is a comparator
At 24, the signal is converted into a binary digital signal according to the sign of the signal. This signal is delayed by the delay circuit 8 having a delay time τ, and an exclusive OR with the recording data output by the data buffer 14 is output by the exclusive OR 18. This output corresponds to the product of the recording data and the error signal. U /
In the D counter 22, counting up and counting down are switched by the binary signal. The counter that operates at this time switches between the upper stage and the lower stage in accordance with “0” and “1” of the recording data, and counts in synchronization with the reproduction signal. The new U / D counter value thus obtained gives the next recording waveform.

In the above circuit configuration, the counter 19 starts counting from the point in time when the recording data changes, and at a predetermined count value,
Next, since the recording is stopped until the recording data changes, only the rising and falling recording waveforms of the data are set. Also, since the numerical value of the U / D counter is independent in the upper and lower stages, there is an advantage that the rising recording waveform and the falling recording waveform are controlled independently.

In addition, a recording waveform generation circuit 1 and a recording waveform control circuit 5
The recording waveform can be set independently for a recording data pattern of about several bits by giving the recording data string identification function of several bits or less. by this,
The optimum recording waveform can be set for each of various recording patterns in which the difference in the optimum recording waveform is predicted by the nonlinearity of the heat flow. FIG. 4 shows a circuit configuration in a case where a recording waveform is independently set for a data pattern of three bits of recording data. Since the basic circuit configuration is the same as the circuit of FIG. 3, only the circuit configuration of the recording waveform generation circuit 1 and the recording waveform control circuit 5 is shown here.

The recording waveform generating circuit 1 includes a counter 19 that counts up in a clock cycle τ, and a shift register that outputs three bits of immediately preceding recording data to a multiplexer.
25 is required. The multiplexer 20 selects a U / D counter group 26 composed of a plurality of U / D counters based on the three bits of the output of the shift register, and further calculates the value of the selected U / D counter based on the value of the counter 19. D
Send to / A converter 21. As a result, the recording waveforms corresponding to “0” and “1” are each independently determined by a 3-bit data pattern including data before and after the recording waveform.

The recording waveform control circuit 5 also converts the immediately preceding 3 bits of the recording data sent from the reference waveform generation circuit 6 into a decoder 27.
Is provided. 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 reproduced signal among the plurality of U / D counter groups 26. Thus, the recording waveform for the predetermined data pattern is controlled completely independently of the other recording waveforms.

(Effects of the Invention) According to the present invention, by compensating the recording waveform by the feedback system, the characteristics of the recording circuit and the recording medium according to
Optimum recording power and recording waveform can be obtained, and high recording density can be obtained.

[Brief description of the drawings]

1 is a system diagram showing one embodiment, FIG. 2 is an explanatory diagram showing operation waveforms of respective parts of the circuit of FIG. 1, FIGS. 3 and 4 are system diagrams showing another embodiment, FIG. FIG. 1 is a system diagram for explaining a conventional technique. In the figure, 1 ... a recording waveform generating circuit, 2 ... a recording circuit, 3 ... a recording medium, 4 ... a reproducing circuit, 5 ... a recording waveform control circuit, 6 ...
... A reference waveform generation circuit.

Claims (2)

(57) [Claims] An optical disk device for recording information on a recording medium using a light beam receives an information data sequence and a recording waveform control signal, and based on the information data sequence,
A recording waveform generating circuit for outputting a signal having a waveform set by the recording waveform control signal, comprising a cascade connection of a pulsating circuit and an adaptive transversal filter; and an output signal of the recording waveform generating circuit as an input. A recording circuit that records the information data sequence on the recording medium based on the signal, a reproduction circuit that reproduces the information data sequence recorded on the recording medium and outputs a reproduction signal, and the information data sequence. A reproduction signal output from the reproduction circuit, and a reference waveform generation circuit that outputs a reference reproduction signal having an ideal reproduction signal waveform in synchronization with the reproduction signal; and a reproduction signal output from the reproduction circuit. A signal and a reference reproduction signal output from the reference waveform generation circuit are input, and a recording waveform control signal is output to the recording waveform generation circuit so that both input waveforms match. Optical disk apparatus characterized by comprising a recording waveform control circuit. 2. An optical disk apparatus for recording information on a recording medium using a light beam, wherein an information data sequence and a recording waveform control signal are input, and based on the information data sequence,
A recording waveform generating circuit that outputs a signal having a waveform set by the recording waveform control signal and includes an arbitrary waveform generating circuit capable of setting an amplitude of an output waveform at a specific time, and an output signal of the recording waveform generating circuit being input. A recording circuit that records the information data sequence on the recording medium based on an input signal; a reproduction circuit that reproduces the information data sequence recorded on the recording medium and outputs a reproduction signal; A reference waveform generation circuit that receives a data string and a reproduction signal output from the reproduction circuit, and outputs a reference reproduction signal that is an ideal reproduction signal waveform in synchronization with the reproduction signal; The read reproduction signal and the reference reproduction signal output from the reference waveform generation circuit are input, and a recording waveform control signal is output to the recording waveform generation circuit so that both input waveforms match. Optical disk apparatus characterized by comprising a recording waveform control circuit that.