JPH0469864A - Automatic waveform equalizing circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for reproducing data recorded on a recording medium such as an optical disk, depending on differences in characteristics of the recording medium, or
Automatic waveform that continuously changes the constant of the equalization circuit in response to changes in resolution between the inner and outer circumference of the disk, always performing optimal waveform equalization and reproducing good data with few errors. Regarding equalization circuits.

[Conventional technology]

Up to now, various algorithms have been proposed for waveform equalization devices. The parameters to be determined, such as the delay amount of the delay circuit and the attenuation amount of the attenuation circuit, are controlled by an address signal or a control signal recorded in advance on a recording medium to control the equalization characteristics.

Furthermore, the waveform equalization circuit described in JP-A-1-165070 measures the pulse width of an input waveform at multiple amplitude levels and compares it with a target pulse width. Set constants.

[Problem to be solved by the invention]

The waveform equalization device described in JP-A-63-122061 controls the constants of the equalization circuit using an address signal, so it can handle changes in the reproduced waveform due to the characteristics of the optical disk recording medium, differences in the recording state, etc. is not taken into account,
Certain waveform equalization is performed depending on the address position. Furthermore, the waveform equalization circuit described in JIFI-J, No. 165070 has a problem in that the waveform equalization circuit is complicated.

An object of the present invention is to constantly perform optimum waveform equalization in consideration of differences in characteristics and recording conditions of optical disc recording media, and to reproduce data in good quality.

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the present invention. In FIG. 1, a specific information detection circuit 1 detects a reproduction waveform of preformatted specific information included in an optical disc reproduction signal input from an input terminal, and an amplitude sampling circuit 2 detects a plurality of amplitudes of the reproduction waveform of the specific information. sampled. A constant setting circuit 3 determines the difference between the sampled amplitude value and a target waveform amplitude, and sets a constant for the waveform equalization circuit 4.

With such a configuration, the purpose of item L can be achieved.

[Effect]

The present invention changes the equalization characteristics of the waveform equalization circuit to always perform optimal waveform equalization regardless of the data reproduction position on the optical disk recording medium.

〔Example〕

An example in which the optical disk device that performs waveform equalization is a 5.25-inch sample servo type optical disk will be described below. The data format of a 5.25-inch sample servo type optical disk is shown in FIG. 3. This format consists of 43 segments consisting of -sectors (18 bytes). The first two bytes of each segment are always preformatted with servo bytes as shown in FIG. The first half of this servo bite (No.
, 1) has a wolves bit for tracking, and the latter half (No, 2) has a clock bit for extracting the clock. The reproduced waveform of this clock pit can be regarded as an isolated waveform. Further, since the existing position can be easily detected by a reproducing circuit, in this embodiment, the specific information is a glock bit, and an automatic waveform equalization circuit is configured.

FIG. 2 shows an embodiment of the present invention and a waveform diagram. When the three-tap transversal filter shown in FIG. 5 is used in the waveform equalization circuit 4 shown in FIG. 2(a), the delay circuit 9. Let the delay amount τ of lO be the bit interval T. Second
In Figure (a), the reproduced waveform read out from the optical disc is input from the input terminal. The reproduced waveform of the glock pit is detected by the clock bit detection circuit 5 from the width of the input reproduced waveform. Glock bit detection circuit 5
Figure 2(b) shows the detected waveform detected by the glock bit reproduction waveform shown in Figure 2(b). , B, and C are sampled by the amplitude sampling circuit 2.

The sampling method is to sample the amplitude value by A/D conversion. sampled data V A,
V e and V c are preset A and B.
.

C MA, M, of target value data 7 for each point.

A comparison operation is performed for each data sampled by Mc and the comparison operation circuit 4, and M A" Ca V H+ C+ V AM -= C
1V a + C2V A+ Co V cM c =
Constant C6, C that becomes C+ V c + Cx V −
Calculate I and CI. Thereafter, the constant setting circuit 3 sets the constants of the waveform equalization circuit 4 to C6, C, and so on.

A control voltage such as C3 is output, and a constant of the waveform equalization circuit 4 is set. That is, a control voltage is applied to the multipliers 11, 12, and 13 of the transversal filter shown in FIG. 5, and the multiplication coefficients C8, C, , C, are optimally set for the reproduced data.

As an example, in the case of a 5.25-inch optical disc, the case where the innermost circumference is 30 mm will be explained. The clock bit reproduction waveform at this time is shown in Fig. 6. If the peak of the clock bit reproduction waveform is set to time O, sample the amplitudes A, B, and C at times iT and O, respectively, and obtain the target value amplitude data. The coefficients Co, CI, C of the multiplier 11゜12.13 of the transversal filter in Fig.
Set I as follows.

Co=Cz=0.15 C,=1.19 Each multiplier 11°12 with the above coefficient set,
The outputs 11-a, 12-a, and 13-a of the waveform equalizer 13 are as shown in FIG. figure(
As shown in C), it becomes O at the adjacent code position, and code amount interference can be eliminated.

In this way, in order to perform good data reproduction without code amount interference, the clock bit reproduction waveform shown in FIG. 2(b), that is, the isolated response waveform at the position where reproduction is performed, is the target. If waveform equalization is performed to obtain the waveform shown in FIG. 2(C) (generally a raised cosine waveform), good data reproduction without code amount interference can be performed.

Moreover, when using a transversal filter in the waveform equalization circuit 4 of FIG. 2(a), the fifth
If a transversal filter with an increased number of taps and a finer delay time is used instead of the three-tap transversal filter shown in the figure, more accurate waveform equalization can be performed.

Next, an embodiment constructed using a digital circuit is shown in FIG. 7. The optical disc reproduction waveform inputted from the input terminal becomes a digital signal to the A/D converter 15A. The arithmetic circuit 18 extracts the amplitude data VA, Vs, Vc of the clock bits at the delay time τ of the delay circuits 19 and 20 of the transversal filter from the digitized signal by the clock bit extraction circuit 16. Amplitude data MA for the squared cosine waveform stored in the data and register 17.

Compare M, , Mc and calculate the transversal filter's multiplication coefficient G o, CIs C! Calculate. The outputs of the multipliers 21, 22, and 23 that have been multiplied by the output optimal multiplication coefficients G O, CI, C* are sent to the adder 24.
are added and output. The output data is data without code amount interference, and good data reproduction with few errors can be performed. Note that the circuit can be simplified by using a microcomputer in place of the arithmetic circuit 18 and register 17 for setting the multiplication coefficients of the waveform equalization circuit, and calculating the multiplication coefficients through software processing.

In this example, the specific information is the clock bit of the sample servo optical disc format, but if the reproduced waveform based on other information can also be regarded as an isolated waveform, the same effect can be achieved by detecting the reproduced waveform. Therefore, it can be used even in an optical disk system that does not use the sample servo method.

〔Effect of the invention〕

According to the present invention, when reproducing data from an optical disc recording medium, by always performing optimal waveform equalization for changes in resolution depending on the inner and outer circumference of the disc, differences in characteristics of the recording medium, etc., good data with few errors can be obtained. can be played.

In addition, since it can be realized with a simple circuit, it has a great practical effect, and by digitizing it, it can be made into an IC that includes other signal processing circuits, and it is possible to reduce costs and space.

[Brief explanation of the drawing]

Fig. 1 is a principle block diagram of an embodiment of the present invention, Fig. 2 is a block diagram and waveform diagram of the first embodiment of the invention, and Fig. 3 is a data format of a 5.25-inch sample servo type optical disk. Figure 4 is a format diagram of the servo byte, Figure 5 is a block diagram of the 3-tap transversal filter of the waveform equalization circuit, Figure 6 is a waveform diagram showing an example of waveform equalization, and Figure 7 is the main FIG. 3 is a block diagram of a second embodiment of the invention. 1...Specific information detection circuit 2...
...Amplitude sampling circuit 3...Constant setting circuit 4...Waveform equalization circuit 5...Glock bit detection circuit 6...・
......Comparison calculation circuit 7...Target value data 8...Input terminal 9, lO...Delay circuits 11 to I3...Multiplier 14... Adder 15... Output terminal 16... A/D converter 17... Glock Pit extraction circuit 18・
......Data register 19...
・Arithmetic circuits 20, 21...Delay circuits 22-24...Multiplier 25...Adder power Figure 6 Porridge Figure 7

Claims (1)

[Scope of Claims] 1. In a waveform equalization circuit that performs waveform equalization that converts the waveform of data read from a recording medium into a waveform suitable for signal processing, An automatic waveform geometric ratio comprising a circuit for extracting reproduced waveform data of specific information, a circuit for setting constants of a waveform equalization circuit based on the data, and a waveform geometrical circuit whose characteristics can be changed by constants of parameters. circuit. 2. The automatic waveform equalization circuit according to claim 1, wherein a specific waveform used as a reference when changing the constant of the waveform geometric ratio circuit is a reproduced waveform of a clock bit preformatted on a recording medium.