KR100521666B1 - Jitter measuring method utilizing A/D conversion and device - Google Patents

Abstract

There is provided a jitter measurement device for reproducing signals from an optical disk having a simple circuit configuration and capable of effectively measuring jitter components. A matrix circuit 4 supplies the RF signals to the analog / digital conversion circuit 6. Secondly, the computer 8 calculates a slice level from the digitized data of the RF signals. The computer 8 calculates a time point at which the RF signals become the indicated slice level by interpolating based on the sampling frequency of the analog / digital conversion circuit 6 and the digital data at the sampling point in the vicinity of the slice level. . The computer 8 calculates each time width between the time points at which the RF signals are at the slice level, and calculates the jitter component of the reproduction signal based on each time width.

Description

Jitter measuring method utilizing A / D conversion and device

The present invention provides a jitter measuring device for signals reproduced from an optical disc, and a method for measuring jitter for a reproduced signal of an optical disc, which stores digital data according to the indicated modulation rule to measure the jitter component of a reproduction signal of the optical disc. It is about. In addition, the present invention relates to a method and a device for optical disc recording and / or reproduction.

An optical disc drive that reproduces an optical disc having digital data stored thereon detects reforming (RF) signals and binarizes these RF signals to generate digital data. In particular, the optical disc drive binarizes the RF signals at the indicated slice level as shown in FIG. 7A and generates digital data as shown in FIG. 7B.

Moreover, digital data modulated according to the indicated modulation method is generally recorded on the optical disc. For example, for a so-called compact disc, assuming that one period of digital data is T, the signal to be recorded is modulated from a signal having a period of 3T to a signal having 11T, and the waveform of each period is recorded randomly. As another example, for a digital video disc, assuming that one period of digital data is T, the signal to be recorded is modulated from a signal having a period of 3T to a signal having 14T, and the waveform of each period is randomly recorded. An optical disc drive in which digital data modulated in accordance with the indicated modulation method is generally recorded, reproduces signals from the optical disc; These signals are binarized to generate digital data.

By the way, the digital data binarized by the optical disk drive is generally reproduced in such a way that noise is raised in the cyclic direction, i. For example, in the case of picking up only a waveform having a period of 3T among RF signals reproduced from an optical disk, the waveform period of this RF signal is 3T ± σ (σ: jitter) with a jitter component with respect to the theoretical period 3T. Component).

The reason why such binarized digital data is reproduced including jitter components is to be considered, for example, the influence of noise included in the recording signal of the optical disc, or the influence from the characteristics of the optical pickup detecting signals recorded on the optical disc. Can be.

Currently, jitter measuring devices are known which detect jitter components of digital data reproduced from optical discs. The jitter measuring device measures the jitter component of the RF signals reproduced from the optical disc. This is used to obtain the characteristics of the optical disk or the optical pickup.

The following describes first to third jitter measurement devices currently used to measure the jitter component of RF signals reproduced from an optical disc.

One known jitter measurement device currently used to measure jitter components uses an integrated circuit to measure the jitter component by calculating the time width of the digital data as a voltage value.

First, as shown in FIG. 8, the first jitter measuring device binarizes the RF signals at the indicated slice level to generate digital data. Secondly, the first jitter measurement device allows the integrated circuit to be operated at a time point at which the RF signal reaches the slice level, ie at the leading edge of the digital data. Thirdly, the first jitter measurement device causes the integrated circuit to stop at a time point at which the RF signal reaches the next slice level, ie at the trailing edge of the digital data. The first jitter measuring device measures the output voltage from the integrated circuit in time span of digital data.

Therefore, the first jitter measuring device can detect the jitter value converted into the voltage value? V by comparing the output voltage from the integrated circuit with the voltage value corresponding to the integrated period.

Since the characteristics of the integrated circuit are determined in accordance with the time constant, the first jitter measuring device uses one (1) integrated circuit so that the waveform of period 1 of the plurality of waveforms modulated and recorded on the optical disk is Recall that only the corresponding jitter component can be detected. That is, if the optical disc to be reproduced is a compact disc, the first jitter measuring device can detect only the jitter component of the waveform having period 3T by using one (1) integrated circuit, For example, it is not possible to detect jitter components of waveforms having periods 4T to 11T.

The second known jitter measurement device currently used to measure the jitter component has adopted a device which is a so-called "time interval analyzer". It uses a high speed clock to count the time span of the digital data and uses the count output to detect jitter components. As shown in FIG. 9, the second jitter measurement device binarizes the RF signals at the indicated slice level to generate digital data. Secondly, the second jitter measurement device not only operates the clock circuit at a time point at which the RF signal reaches the slice level, ie at the leading edge of the digital data, but also starts to count the clock number output from the clock circuit. do. Thirdly, the second jitter measurement device causes the clock circuit to stop at a time point at which the RF signal reaches the next slice level, ie at the trailing edge of the digital data. The number of counts at this point is regarded as the time span of the digital data for the second jitter measuring device.

Therefore, the second jitter measuring device can detect the jitter value by comparing the count number of the counter with the count number in the indicated period.

The third known type of jitter measuring device currently used to measure the jitter component employs the first jitter measuring device and the second jitter measuring device.

First, as shown in FIG. 10, the third jitter measurement device binarizes the RF signals at the indicated slice level to generate digital data. During this operation, the third jitter measurement device continues to generate a clock at the clock frequency indicated by the clock circuit. Secondly, the third jitter measurement device not only operates the clock circuit at a time point at which the RF signal reaches the slice level, i. To count. In addition, the third jitter measurement device begins to operate an integrated circuit at the leading edge of digital data. Thirdly, the third jitter measurement device stops operating the integrated circuit at the timing of the clock generated immediately after the leading edge of the digital data. The third jitter measuring device then measures the output voltage V ₁ of the integrated circuit and converts the output voltage V ₁ into a time width that is the first time width t ₁ of the digital data.

The third jitter measurement device begins to operate the integrated circuit once again at the clock timing just before the time point at which the RF signal reaches the next slice level, ie at the clock timing just before the trailing edge of the digital data. The third jitter measurement device then stops operating the integrated circuit at the time point at which the RF signal reaches the next slice level, ie at the trailing edge of the digital data.

The third jitter measurement device detects the count number of the counter at the trailing edge of the digital data. Based on this count number and the clock frequency mentioned above, the device calculates the time width from the timing of the clock generated just before the leading edge of the digital data to the clock timing generated immediately after the trailing edge of the digital data. This time span will be referred to as the second time span t ₂ of digital data. Further, the third jitter measuring device measures the output voltage V ₃ of the integrated circuit at the point, and converts the output voltage V ₃ into a time width that becomes a third time width t ₃ of digital data. Convert.

Therefore, the third jitter measuring device may measure the time width of the digital data by adding up the first time width t ₁ , the second time width t ₂ , and the third time width t ₃ . . Furthermore, the third jitter measuring device can detect the jitter value by comparing the time width of the digital data with the theoretical value.

However, the present first to third jitter measuring devices described above have the following problems;

In the first jitter measuring device, since it uses an integrated circuit that measures the time width analog, it is difficult to measure the time width in a stable state, which is susceptible to noise. In addition, since the first jitter measuring device cannot measure a waveform having more than one period using one integrated circuit, when the jitter component of a waveform having a plurality of periods is desired, It requires as many integrated circuits as there are waveforms. That is, in the first jitter measuring device, for example, nine integrated circuits having different time constants are needed to detect all jitter components of a waveform having periods 3T to 11T included in a compact disc. Therefore, the first jitter measurement device has a complicated hardware configuration.

Since the second jitter measuring device counts the clock to measure the time width, a time width shorter than the clock period cannot be measured. In addition, since the second jitter measuring device used a high speed clock, the processing circuit was inevitably complicated. Therefore, it was difficult to save money.

Since the third jitter measuring device uses an integrated circuit for measuring the time width analog, it is difficult to measure the time width in a stable state easily affected by noise. In addition, the third jitter measuring device has a complicated circuit configuration and therefore cannot be inexpensive. In addition, since the third jitter measuring device uses integrated circuits, it requires as many integrated circuits as the number of waveforms having periods to be measured. Therefore, the third jitter measuring device has a complicated hardware configuration.

It is an object of the present invention to overcome or significantly improve at least some of the inconveniences of the prior art.

According to the invention, there is provided a device for measuring jitter of a periodic signal reproduced from an optical disc, said device comprising:

An analog-digital means for converting periodic signals reproduced from an optical disk on which digital data according to an indicated modulation rule is stored,

Means for sampling the reproduced periodic signals at a predefined sampling frequency and means for determining the level of the reproduced periodic signal at each sampling point; And

Jitter calculating means for calculating the time points at which the reproduced periodic signal is equal to a predefined slice level,

Means for calculating a time interval between the time points at which the reproduced periodic signal is equal to a predefined slice level;

And means for calculating the jitter component of the period based on the time interval.

Always jitter calculation means,

Means for calculating a peak value of the periodic signal at each of the respective sampling points;

The apparatus may further include means for calculating the slice level according to the peak value.

The jitter calculating means may further comprise means for determining which of the sampling points is the absolute value of the reproduced periodic signal equal to or above the slice level.

The peak value is based on the periodic signal level of each of the sampling points where the absolute value of the periodic signal level is greater than or equal to 1/4 of a predefined theoretical amplitude value for a predetermined minimum length periodic waveform of the optical disk. Can be calculated by the jitter calculating means.

The peak value determines where the periodic signal level exceeds a predefined theoretical amplitude value for a periodic waveform of a predetermined minimum length of the optical disk for a period of time greater than or equal to one-half period of the minimum periodic waveform. It can be calculated by the jitter calculating means.

The jitter calculating means may further comprise means for determining a reference time interval by calculating a time interval of each period of the periodic signal based on the time point at which the level of the periodic signal is equal to or greater than the slice level. .

The jitter calculating means may extract a time interval for each wave of the periodic signal based on the reference time interval.

The reference time interval may be selected to be equal to a periodic waveform of a predetermined minimum length of the optical disk or a waveform of a predetermined maximum length of the optical disk.

The jitter calculating means may calculate the jitter component of the periodic signal according to the reference time interval.

The jitter calculating means may calculate the jitter component of the periodic signal according to the characteristics of the multiple periods of the periodic signal.

Jitter calculation means According to the jitter component of the periodic signal can be calculated. here,

sigma = jitter component calculated on the basis of reproduction signals having a waveform of every period of the periodic signal.

σ _i = jitter component calculated based on reproduction signals having a waveform of the periodic signal.

The jitter calculating means can calculate the asymmetry of the level of the periodic signal for each period of the periodic signal.

According to another feature of the invention,

At a predetermined sampling frequency to define points of sampling, a periodic period in which digital data according to the indicated modulation rule is reproduced from an optical disc on which recording is pre-recorded, to generate sample data representing signal level data for each of the sampling points. Sampling the signals;

Calculating successive time points corresponding to each of the sampling points whose signal level exceeds a predetermined slice level;

Calculating time intervals between the successive time points; And

A jitter measurement method is provided that includes calculating the jitter component of the periodic signal based on the time intervals.

Jitter measurement method,

Calculating a peak value for each period of the periodic signal based on the signal level data;

The method may further include calculating the slice level based on the peak value.

In the jitter measurement method, a peak value for each period of the periodic signal may be based on an absolute value of the signal level data for each period.

The peak value for each period of the periodic signal may be defined as a signal level at which the absolute value is equal to or greater than a quarter of a predefined theoretical amplitude value for a predetermined minimum length period.

The peak value for each period of the periodic signal may be defined as the signal level at which the absolute value is maintained for a time interval equal to or greater than one-half period of the predetermined theoretical minimum periodic waveform.

The jitter measurement method may further comprise defining a reference time interval such that the signal level values are equal to the time interval between successive sampling points that are equal to or greater than a predetermined slice value.

The jitter measurement method,

The method may further include defining a reference time interval to be equal to a time interval for a predefined minimum length periodic waveform, and calculating the jitter component based on the reference time interval.

The jitter measurement method is:

The method may further include defining a reference time interval to be equal to a time interval for a periodic waveform of a predefined maximum length, and calculating the jitter component based on the reference time interval.

The jitter measuring method may further include calculating the jitter component of the periodic signal based on the reference interval during the predetermined period of the periodic signal.

The jitter measurement method may further comprise calculating the jitter component of the periodic signal based on the reference interval during the plurality of periods of the periodic signal.

The jitter measurement method may further comprise calculating the jitter component of the periodic signal based on the reference interval during all periods of the periodic signal.

The jitter component of the periodic signal is Can be calculated according to. here,

sigma = jitter component calculated on the basis of reproduction signals having waveforms of all waveform periods of the periodic signal.

σ _i = jitter component calculated based on a predetermined waveform period of the periodic signal (1).

The jitter measurement method may further comprise calculating an asymmetry of the periodic waveform level in the periodic signal.

According to another aspect of the present invention, there is provided a recording and / or reproducing system of an optical disc in which the characteristics are as follows:

A reproduction method for reproducing an optical disc storing digital data according to an indicated modulation rule and outputting data in accordance with recorded signals;

Analog / digital conversion means for converting reproduction signals reproduced by the reproduction method into digital data sampled at the indicated sampling frequency and representing signal levels at each sampling point; And

Correcting and calculating the time point at which the reproduction signal reaches the slice level based on the sampling frequency and the signal levels in the vicinity of the indicated slice level, and the angle between the time points at which the reproduction signal reaches the slice level. Jitter calculating means for calculating a time width, calculating a jitter component of a reproduction signal based on the respective time widths, and finally controlling the reproduction measurements based on the jitter component.

According to another aspect of the present invention, there is provided a method of playing an optical disc, the characteristics of which are as follows:

Reproducing an optical disc storing digital data according to the indicated modulation rule, and outputting data in accordance with the recorded signals;

Converting reproduction signals in which digital data according to the indicated modulation rule is stored into digital data sampled at the indicated sampling frequency and representing the signal level at each sampling point;

Correcting and calculating a time point at which the reproduction signal reaches the slice level based on the sampling frequency and the signal levels in the vicinity of the indicated slice level;

Calculate each time width between time points at which the playback signal reaches the slice level;

The jitter component of the reproduction signal is calculated on the basis of the respective time periods, and

The regenerative measurements are controlled based on the jitter component.

Embodiments of the present invention are described by way of example only with reference to the accompanying drawings in order to better understand the present invention.

Referring to the drawings, FIG. 1 is a block diagram illustrating the application of an embodiment of the invention as a characteristic test device. As shown in Fig. 1, the characteristic test device has the following characteristics: an optical pickup 2 to be tested, a test bench 3 on which an optical disk is installed, and owned by the optical pickup 2; A matrix circuit 4 which is provided with an output from the photo detector provided to output the reforming (RF) signals, and a servo providing servo control for the reproducing drive of the optical disc based on the output from the matrix circuit 4. Servo control circuit 5.

In addition, this characteristic test device 1 comprises: a first analog / digital conversion circuit 6 for converting RF signals from the matrix circuit 4 into digital data, and a first analog / digital conversion circuit. First memory (7) for temporarily storing the output from (6).

In addition, the characteristic test device 1 processes the operation of the jitter component on the basis of the digital data temporarily stored in the memory 7 and displays the result of the processing, and based on the processing result, the servo control circuit 5 is operated. Computer 8 to be controlled.

The optical pickup 2 is a close inspection of the property test device 1. This optical pickup 2 can be freely attached to or removed from the characteristic test device 1, for example. The optical pickup 2 also includes a laser diode, a beam splitter, an object lens, a light detector, and the like. Moreover, the optical pickup 2 causes the laser emitted from the laser diode to be collected on the optical disk through a beam splitter, an objective lens or the like. The optical pickup 2 then reflects light from the image on the photo detector. The photo detector owned by the optical pickup 2 is a photoelectric conversion element; This converts the reflected light forming the image into electrical signals.

The optical pickup 2 comprises a plurality of light detectors. 2 shows an example of a plurality of light detectors mounted on the optical pickup 2. For example, as shown in FIG. 2, the optical pickup 2 comprises four photo detectors A to D arranged in the form of a 2 × 2 matrix and photo detectors A arranged in such a manner. Light detectors (E) and (F) for side spot inspection on both sides of (D) to (D). Such photo detectors (A) to (F) are employed in the optical pickup, for example in a so-called three-spot method, in which three laser spots are emitted to the optical disk. In the three-spot method, the main beam serving as the center light is irradiated to the photodetectors (A) to (D). In other words, the reflected light for the memory bit recorded in the tracks of the optical disc is irradiated to the light detectors (A) to (D). The photo detectors (E) and (F) are radially installed on both sides of the photo detectors (A) to (D). In a three-spot scheme, side beams are irradiated to the photo detectors (E) and (F). For example, light reflected at the tracks edge of the optical disk is irradiated to these photo detectors (E) and (F).

The test bench 3 provided with the optical disk rotates and drives the optical disk to rebuild the optical disk. In addition, an optical disc installed in the test bench 3 is used as a reference for the characteristic test device 1. That is, the characteristic test device 1 measures the characteristic of the optical pickup 2 based on the reproduction signals of the optical disc used as a reference for the characteristic test device 1.

The matrix circuit 4 to which the signals A to F which are the outputs from each of the photo detectors A to F owned by the optical pickup 2 are supplied with the signals A to F Generate reconstruction (RF) signals, focus error (FE) signals, and tracking error (TE) signals. For example, the matrix circuit 4 generates RF signals, FE signals and TE signals based on the signals A to F as follows: The matrix circuit 4 generates signals A; Process A + B + C + D based on (D) and then generate RF signals; Further, the matrix circuit 4 processes (A + C)-(B + D) based on the signals A through (D) and outputs the processing result as an FE signal: that is, the matrix circuit 4 Outputs FE signals based on a non-point aberration method; Finally, the matrix circuit 4 performs E-F processing based on the signals E and F, and outputs the processing result as a TE signal.

Moreover, digital data modulated according to the indicated modulation method is recorded as optical data. For example, in a compact disc, assuming that one period of digital data is T, signals having periods of 3T to 11T are recorded at random. As another example, in a digital video disc, assuming that one period of digital data is T, signals having periods of 3T to 14T are randomly recorded. Such digital data modulated according to the indicated modulation method is generated by binarizing the RF signals generated by the matrix circuit 4 at the indicated slice level.

The matrix circuit 4 supplies the RF signals, FE signals and TE signals processed in the above manner to the servo control circuit 5. The matrix circuit 4 also supplies RF signals to the first analog / digital switched circuit 6.

The servo control circuit 5 servo controls the drive of the optical disc during reproduction based on the RF signals, the FE signals and the TE signals. In particular, the servo control circuit 5 drives the biaxial actuator for operating the objective lens of the optical pickup 2 until the FE signal reaches zero based on the RF signals, and executes the focus servo control. The servo control circuit 5 drives the biaxial actuator for operating the objective lens of the optical pickup 2 until the TE signal reaches zero based on the TE signals and executes tracking servo control. The servo control circuit 5 detects the DC component of the FE signals and executes thread servo control until the DC component reaches zero. In addition, the servo control circuit 5 executes the inclination servo control for controlling the inclination of the optical disk based on the RF signals. In addition, it is also preferable that the servo control circuit 5 is provided with a separate structure to measure the inclination of the optical disk to execute the inclination servo control.

The analog / digital conversion circuit 6 is suitably sufficient to store a waveform of the minimum theoretical frequency for digital data according to the indicated modulation method, for example a waveform having a frequency of 3T for a compact disc, generated from RF signals. Samples RF signals at a fast sampling frequency.

The analog / digital conversion circuit 6 converts the RF signal into digital data, for example, at a sampling frequency of about 30 MHz. The analog / digital conversion circuit 6 supplies the RF signals converted into digital data to the memory 7.

The memory 7 temporarily stores the RF signals converted into digital data by the analog / digital conversion circuit 6.

The computer 8 includes an interface section 8a; Data storage section 8b; An output section 8c; And a processing unit 8d and the like. The interface unit 8a outputs control signals for controlling the servo control circuit 5 to the servo control circuit 5. The data storage 8b stores various processing programs corresponding to each measurement item of the optical pickup 2 in the characteristic test device 1. The output section 8c displays the results of measuring the characteristics of the optical pickup 2.

The processing section 8d of the computer 8 converts the RF signals stored in the first memory 7 into digital data, and then detects the jitter component of the RF signals based on the read data.

Further, when the processing section 8d of the computer 8 is processed according to each measurement item, the following processing is performed on the data stored in the memory 7: For example, the processing section 8d may perform a filter operation; Peak level operation; Calculating a waveform period; Calculating a phase difference between two signals; Signal extraction by the level window; And a signal extraction operation by a periodic window.

Next, as shown in Figs. 3, 4, 5 and 6, processing contents for measuring the jitter component items of the optical pickup 2 using the characteristic test device 1 will be described.

When the optical pickup 2 is installed by the user and the start of operation is instructed, the characteristic test device 1 starts processing from step S1 in the flowchart as shown in FIG.

In step S1, the characteristic test device 1 reproduces the optical disc and detects, for example, the RF signals shown in A of FIG.

In step S2, the characteristic test device 1 converts the RF signals into digital data through the analog / digital conversion circuit 6 and quantizes them as shown in B of FIG. The quantized RF signals are sequentially stored in the memory 7.

In step S3, the characteristic test device 1 detects the peak value of each waveform of the RF signals as shown in FIG. 4C based on the quantized RF signals. That is, for example, in the RF signals reproduced from the optical disk, waveforms having components of 3T to 11T periods are randomly included. Therefore, the RF signals become waveforms whose levels vary with + and-in the vertical direction. The characteristic test device 1 detects the peak value on the plus side and the peak value on the minus side for each waveform in the above variation.

Further, for the process of measuring the peak value in step S3, the processing unit 8d reads the quantized data stored in the memory 7. The same procedures are taken after the next step S4.

In the next step S4, the characteristic test device 1 calculates the slice level while the RF signals are being binarized, as shown in FIG. 4D based on the peak values of the detected RF signals. In this process, the characteristic test device 1 calculates the slice level by performing an operation described as follows;

For example, the characteristic test device 1 calculates the average value of the peak values on the plus side and the average value of the peak values on the minus side for all waveforms, and then determines the intermediate point of these average values as the slice level. Alternatively, the characteristic test device 1 can determine at the slice level a value representing an offset added to the intermediate point. Moreover, the characteristic test device 1 can detect only the indicated waveform of the indicated period included in the RF signals, instead of the peak values of all the waveforms: for example, it detects only the waveform of 3T and thus the 3T. The intermediate point in the average values of the peak values of the waveform may be determined as the slice level.

In addition, in the case of calculating the slice level, the characteristic test device 1 may use the detected peak value by adding the indicated limit to remove the noise component or the like.

For example, the characteristic test device 1 detects only peak values having a level of 1/4 or more with respect to the theoretical amplitudes of the RF signals of the optical disk to be reproduced. By adding a limit toward the amplitude direction while detecting the peak value, the characteristic test device 1 can remove the noise component and as a result can calculate the correct slice level. As another example, the characteristic test device 1 may only peak when the time period between the peak value and the other peak value is 1/2 or more of the period of the shortest period waveform (e.g., 3T) of the RF signals of the optical disk to be reproduced. Detect the value.

By adding a restriction towards the time base direction while detecting the peak value, the characteristic test device 1 can remove the noise component and as a result can calculate the correct slice level.

Furthermore, it is further mentioned that when setting the slice level for the characteristic test device 1, the user can set the value randomly or add an offset to the slice level calculated by the above procedures: Any of these is acceptable.

In step S5, the characteristic test device 1 separates the RF signals into levels using the calculated slice level, and then calculates the period of each waveform defined by the slice level. The characteristic test device 1 calculates these periods based on, for example, the sampling frequency of the analog-to-digital conversion circuit 6 discussed above. The characteristic test device 1 then calculates the longest period or the shortest period based on the calculated periods of each waveform. If the optical disc to be reproduced is a compact disc, the shortest period is 3T or 670 ms.

In step S6, the characteristic test device 1 calculates at what speed the characteristic test device 1 plays the optical disc on the basis of the calculated longest or shortest period, as shown in E of FIG. do. That is, the characteristic test device 1 compares the calculated longest period or the shortest period with the period of the theoretical value and calculates at what speed the current optical disc is reproduced.

Note that if the speed at which the optical disc is currently being reproduced is known in advance, the characteristic test device 1 proceeds directly from step S4 to step S7 without processing steps S5 and S6. .

In step S7, the characteristic test device 1 calculates the time width of each waveform, as shown in F of FIG.

Next, step S7 is clarified using an example of calculating the time width of a part of the waveform X shown in FIG. 5 (b) among the RF signals as shown in FIG. 5 (a). Explain.

The characteristic test device 1 processes steps S11 to S17 as shown in Fig. 6 to calculate the time width of the waveform X shown in Fig. 5B. First, in step S11, the characteristic test device 1 obtains quantized data D1 to D6 for a part of the waveform X, as shown in Fig. 5C. Here, the quantized data D1 to D6 include not only the data of the waveform X but also a part of data before and after the slice level with respect to time.

Secondly, in step S12, the characteristic test device 1 calculates a time point P1 at which the RF signals are at the slice level by interpolating the quantized data D1 and D2. For example, assuming that the quantization data at a level greater than the slice level is + and the quantization data at a level smaller than the slice level is-, RF signals become slice level between two quantization data whose signs are changed. Points must exist. Therefore, the characteristic test device 1 samples the two quantized data at a time point at which RF signals are sliced through interpolation by using the level difference between slice levels of two quantized data over the slice level. The time points obtained can be calculated.

Thirdly, in step S13, the characteristic test device 1 is subjected to the same process as in step S12 above, by interpolating in the quantized data D5 and D6, so that the time point P1 is followed by the RF. Compute the time point P2 at which the signals become slice level.

Herein, in the above steps S12 and S13, an operation method of interpolating quantized data may be used to calculate time points P1 and P2 of the RF signal at the slice level. Note: For example, these can be calculated by linear interpolation. In addition, using quantized data in the vicinity of the slice level, there is no need to calculate them from the two quantized data. Alternatively, it is possible to calculate, for example, the time point at which the RF signals are at the slice level from three data or four data.

Fourthly, in step S14, the characteristic test device 1 calculates the time width t1 between the quantized data D2 sampled immediately after the slice level and the calculated time point P1.

Fifthly, in step S15, the characteristic test device 1 calculates a time width t2 between the quantized data D5 sampled immediately before the slice level and the calculated time point P2.

Sixth, in step S16, the characteristic test device 1 calculates the time width t3 between the quantized data D2 sampled immediately after the slice level and the quantized data D5 sampled immediately before the slice level. do. The characteristic test device 1 may calculate the time width t3 based on the number of samplings between the quantization data D2 and the quantization data D5 and the sampling frequency of the analog / digital conversion circuit 6.

Seventh, in step S17, the characteristic test device 1 adds the time width t1, the time width t2 and the time width t3, which were mentioned above, to obtain the time width of the waveform X. Calculate

As discussed above, the characteristic test device 1 may process the steps S1 to S17 in step S7 to calculate the period of the waveform X.

Moreover, in step S7, the characteristic test device 1 measures the time width of each waveform of the RF signals, that is, the time width of the plurality of waveforms, as shown in FIG. 4 (f). The characteristic test device 1 stores, for example, the calculated time width data of each waveform in the data storage 8b.

In the next step S8, the characteristic test device 1 divides the period of each waveform of the RF signals calculated in the step S7 among the data for every period of each waveform by using a periodic window. Here, if the optical disc to be reproduced is a compact disc, " for every cycle of each waveform " means that all periods of the waveform of the modulation signals contained in the RF signal of the compact disc, i.e., 3T to 11T, Means for every cycle. The periodic window is the time domain for dividing each waveform for every period. For example, if each waveform period of the RF signals that were calculated in step S7 is present in a time width that is greater than or equal to 0T and less than or equal to 3.5T with respect to the theoretical period T, the specific test device 1 may classify it as 3T. Divide or, if present in a time span of 3.5T or more and 4.5T or less for the theoretical period T, the characteristic test device 1 divides it into a rating of 4T.

As described above, the characteristic test device 1 divides the period of each waveform by using a periodic window. It is further mentioned that during the execution of this division, the characteristic test device 1 takes into account the reproduction speed of the optical disc.

In step S9, the characteristic test device 1 measures the jitter component σ of the RF signals for every period based on the divided time span for all the periods mentioned above.

For example, the characteristic test device 1 sums the time widths of waveforms having a period of 3T divided by periodic windows, calculates their average, and calculates how much difference each data has from the average. do. In addition, assuming that the jitter component of each waveform is σ _i , the characteristic test device 1 calculates the calculated jitter component based on the reproduction signals of the waveform of all periods, as shown in Equation 1 below. :

[Equation 1]

As discussed above, the characteristic test device 1 can measure the jitter of the optical pickup 2.

Further, the processing section 8d adds the result of measuring the jitter component to the controlled variable of the focus servo as an offset component. Under the above conditions, the characteristic test device 1 processes once again from step S1 to step S9 as mentioned above. By completing these processes, the characteristic test device 1 can re-measure the jitter by performing feedback to the servo control circuit 5 on the result of measuring the jitter component.

As described above, since the characteristic test device 1 calculates the time width of each waveform in the reproduction signal of the optical disk using the digital processing, the characteristic test device 1 is noise resistant, and the jitter component Can be measured stably. In addition, the particular test device 1 can measure the jitter component for every period included in the RF signals, for example for every 3T to 11T. Moreover, the characteristic test device 1 can easily measure the sum of the jitter components included in the reproduction signal of the waveform of all periods.

The characteristic test device 1 has a very simple circuit configuration. Even if it is necessary to correct the measurement contents, only the processing programs need to be modified, thereby saving the cost.

In addition, when measuring the jitter of the optical pickup 2 by using a system employing a plurality of characteristic test devices 1, correction can be easily performed among the devices, thereby causing unevenness in the measurement results among the respective devices. Don't let that happen.

In addition, by completing the following processes, the characteristic test device 1 can not only measure the jitter component, but also calculate the amplitude of all waveforms in the RF signals.

The characteristic test device 1 calculated the time width of the waveform X in the processing of step S7, as described above. During the above process, the characteristic test device 1 calculates an approximate formula of the waveform X using the quantization data D1 to D6. Based on the above approximate formula, the characteristic test device 1 calculates the peak value of the waveform X. The characteristic test device 1 divides the peak value among all the periodic windows described in step S8 and calculates an average value of the peak values for all periods. In these processes, the characteristic test device 1 can calculate the amplitude of every period in the RF signals.

Finally, the characteristic test device 1 can calculate the asymmetry (unbalance) of the peak value of each period by comparing the amplitudes of all periods calculated through the above processes with each other.

Here, a characteristic test device 1 for measuring the characteristics of the optical pickup 2 has been described. However, it is possible to apply the characteristic test device 1 to the characteristic test device for the optical disc. That is, the characteristic test device 1 described above uses the optical disc installed in the test bench 3 as a reference; Using the optical pickup as a reference, the characteristics of the optical disk can be measured.

In addition, the optical pickup 2 measured by the characteristic test device 1 measured signals A to F using the optical detector shown in FIG. 2; However, the adoption of the present invention is not limited to this kind of optical pickup. For example, it is possible to apply this to optical pickups used in optical magnetic discs or phase change discs. In these cases, since the configuration of the photo detector is generally different from that described in FIG. 2, the circuit configurations of the matrix circuit 4 and the servo control circuit 5 correspond to the optical pickup to be measured. Further, when adopted to the magneto-optical disk, the reproduction signal becomes a difference signal using the Kerr effect, so that the processing contents in the processing section 8d will adopt a program corresponding to the difference signal. .

Moreover, the optical pickup 2 measured by the characteristic test device 1 is not equipped with an objective lens as one body, but a so-called photo coupler including a light emitting device, a prism and a light receiving element on a semiconductor board. Can be. In this case, the optical coupler can be freely attached to or removed from the property test device 1, and the objective lens is mounted to the device.

Embodiments of the present invention also include analog / digital conversion circuitry 6, memory 7, and computer 8, which perform feedback on the measurement results of the jitter components and then optimize playback or recording conditions. Can be employed in a recording and / or reproducing system of an optical disc for recording and reproducing signals under these conditions.

In other words, such an optical disc recording and / or reproducing system is equipped with an analog / digital conversion circuit to which an output from a reproduction signal of the optical pickup is supplied, as well as a conventional circuit configuration of the optical disc, and also an analog / digital conversion circuit. A processor is equipped for calculating characteristics of the reproduction signal based on the output from the.

The processing unit is composed of, for example, a digital signal processor. It measures the jitter component discussed above based on the output data from the analog / digital conversion circuit. The processing unit controls the reproducing circuit so that the reproducing characteristic or the servo characteristic of the recording and / or reproducing system is optimized based on the measurement result. Subsequently, the recording and / or reproducing system of the optical disc can reproduce the optical disc under optimized reproduction conditions.

With respect to this embodiment of the present invention, the jitter measuring device for the reproduction signal of the optical disc converts the reproduction signal of the optical disc into digital data at a predetermined sampling frequency; Interpolate a time point at which the playback signal is equal to or above a predetermined slice level; It also calculates the jitter component of the playback signal.

By the above processes, the jitter measuring device for the reproduction signal of the optical disk is noise resistant, so that the jitter component can be stably measured. In addition, with respect to this embodiment of the present invention, the characteristic test device 1 can measure the jitter component of every period included in the reproduction signal. Moreover, with respect to this embodiment of the present invention, the characteristic test device 1 can measure the sum of the jitter components included in the reproduction signal of the waveform of all periods.

With respect to this embodiment of the present invention, the jitter measuring device for the reproduction signal of the optical disc converts the reproduction signal of the optical disc into digital data at the indicated sampling frequency; Interpolate a time point at which the playback signal becomes the indicated slice level; It also calculates the jitter component of the playback signal.

By the above processes, the jitter measuring device for the reproduction signal of the optical disk is noise resistant, so that the jitter component can be stably measured. In addition, with respect to this embodiment of the present invention, the characteristic test device 1 can measure the jitter component of every period included in the reproduction signal. Moreover, with respect to this embodiment of the present invention, the characteristic test device 1 can measure the sum of the jitter components included in the reproduction signal of the waveform of all periods.

With respect to this embodiment of the present invention, the recording and / or reproducing system of the optical disc converts the reproduction signal of the optical disc into digital data at the indicated sampling frequency; Interpolate a time point at which the playback signal becomes the indicated slice level; The jitter component of the reproduction signal is calculated, and the reproduction signal is feedback controlled based on the jitter component.

By the above processes, with respect to this embodiment of the present invention, the recording and / or reproducing system of the optical disc can reproduce the optical disc under optimized reproduction conditions.

With respect to this embodiment of the present invention, the method of the optical disc converts the reproduction signal of the optical disc to digital data at the indicated sampling frequency and interpolates a time point at which the reproduction signal becomes the indicated slice level; Calculate the jitter component of the reproduction signal; In addition, feedback control of the reproduction signal is performed based on the jitter component.

By the above processes, with respect to this embodiment of the present invention, the reproduction method of the optical disc can reproduce the optical disc under optimized reproduction conditions.

In summary, embodiments of the present invention provide a jitter measuring device for a reproduction signal of an optical disc, a jitter measuring method for a reproduction signal of an optical disc; An optical disc recording and / or reproducing system and optical disc reproducing methods are provided.

In addition, embodiments of the present invention provide not only optical disc recording and / or reproducing systems, but also optical disc reproducing methods capable of optimizing jitter components.

With respect to embodiments of the invention, the jitter measuring device for the reproduction signal of the optical disc has the following characteristics: The reproduction signal of the optical disc in which digital data is stored according to the indicated modulation rule is sampled at the indicated sampling frequency. Analog / digital converting means for converting the signal levels into digital data representing the signal levels at each sampling point; And correcting and calculating a time point at which the reproduction signal reaches the slice level based on the sampling frequency and the signal levels in the vicinity of the indicated slice level, and between time points at which the reproduction signal reaches the slice level. Jitter calculating means for calculating each time width and calculating a jitter component of a reproduction signal based on each time width.

The jitter measuring device for the reproduction signal of the optical disc converts the reproduction signal of the optical disc into digital data sampling at the indicated sampling frequency; Correcting and calculating a time point at which the reproduction signal reaches the slice level; It also calculates the jitter component of the playback signal.

According to one embodiment of the invention, the jitter measuring device for the reproduction signal of the optical disc has the following features: jitter calculating means calculates a peak value of the reproduction signal from the signal level at each sampling point, and the peak value. Set the indicated slice level as mentioned above on the basis of. The jitter measuring device for the reproduction signal of the optical disc calculates the peak value of the reproduction signal and calculates the jitter component of the reproduction signal.

According to one embodiment of the invention, the jitter measuring device for the reproduction signal of the optical disc has the following features: The jitter calculating means uses the indicated time span as a reference, so that the reproduction signal reaches the slice level. From each time width between time points, the time width corresponding to the period of each waveform included in the reproduction signal of the optical disc is extracted, and the jitter component of the reproduction signal is calculated.

The jitter measuring device for the reproduction signal of the optical disc extracts the time width corresponding to the period of each waveform and calculates the jitter component of the reproduction signal.

According to one embodiment of the invention, the jitter measuring device for the reproduction signal of the optical disc has the following characteristics: The jitter calculating means not only calculates the jitter component of the reproduction signal, but also uses the indicated time width as a reference. Extracting a time width corresponding to the period of each waveform included in the reproduction signal of the optical disc from each time width between the time points at which the reproduction signal reaches the slice level, and amplitude of the reproduction signal in the waveform of each period. Calculate

The jitter measuring device for the reproduction signal of the optical disc not only calculates the jitter component of the reproduction signal, but also calculates the amplitude of the reproduction signal of the optical disc with the waveform of each period. According to one embodiment of the invention, the jitter measuring device for the reproduction signal of the optical disc has the following features: The jitter calculating means not only calculates the jitter component of the reproduction signal, but also the reproduction signal of the optical disc with the waveform of each period. Calculate the asymmetry of the amplitude at.

The jitter measuring device for the reproduction signal of the optical disc not only calculates the jitter component of the reproduction signal, but also calculates the asymmetry of the amplitude of the reproduction signal of the optical disc with the waveform of each period.

 According to one embodiment of the present invention, the jitter measuring method for the reproduction signal of the optical disc has the following features: It samples the reproduction signal of the optical disc in which digital data is stored according to the indicated modulation rule at the indicated sampling frequency. Converting them into digital data representing signal levels at each sampling point, which corrects for the time point at which the playback signal reaches the slice level based on the sampling frequency and the signal levels in the vicinity of the indicated slice level; It calculates each time width between the time points at which the playback signal reaches the slice level, and it also calculates the jitter component of the playback signal based on each time width.

In the jitter measuring method for the reproduction signal of the optical disc, it converts them into digital data at the indicated sampling frequency, corrects and calculates the time point at which the reproduction signal reaches the slice level, and also calculates the jitter component of the reproduction signal. Calculate

According to one embodiment of the present invention, the jitter measuring method for the reproduction signal of the optical disc has the following characteristics: It calculates the peak value of the reproduction signal from the signal level at each sampling point and based on the peak value. Set the indicated slice level as mentioned above.

In the above jitter measuring method for the reproduction signal of the optical disc, it calculates the peak value of the reproduction signal and calculates the jitter component of the reproduction signal.

According to one embodiment of the present invention, the jitter measuring method for the reproduction signal of the optical disc has the following characteristics: It is a time point at which the reproduction signal reaches the slice level by using the indicated time width as a reference. From each time span between them, the time period corresponding to the price of each waveform included in the reproduction signal of the optical disc is extracted, which also calculates the jitter component of the reproduction signal.

In the above jitter measuring method for the reproduction signal of the optical disc, this extracts the time width corresponding to the price of each waveform included in the reproduction signal, and calculates the jitter component in the reproduction signal of the optical disc.

According to one embodiment of the invention, the jitter measuring method for the reproduction signal of the optical disc has the following features: It not only calculates the jitter component of the reproduction signal, but uses the indicated time width as the reference, From each time width between the time points at which the reproduction signal reaches the slice level, the time width corresponding to the period of each waveform included in the reproduction signal of the optical disc is extracted, and the amplitude of the reproduction signal is converted into the waveform of each period. Calculate

In the above jitter measuring method for the reproduction signal of the optical disk, it not only calculates the jitter component of the reproduction signal, but also extracts the time width of the waveform of each period.

According to one embodiment of the present invention, the jitter measuring method for the reproduction signal of the optical disc has the following features: It not only calculates the jitter component of the reproduction signal, but also the amplitude of the reproduction signal of the optical disc with the waveform of each period Calculate the asymmetry.

In the above jitter measuring method for the reproduction signal of the optical disk, it not only calculates the jitter component of the reproduction signal, but also calculates the asymmetry of the reproduction signal amplitude in the waveform of each period of the reproduction signal.

Regarding one embodiment of the present invention, an optical disc recording and / or reproducing system has the following characteristics: reproduces an optical disc in which digital data is stored according to an indicated modulation rule, and outputs data in accordance with recorded signals Playing method; Analog / digital conversion means for converting a reproduction signal reproduced by the reproduction method into digital data sampled at the indicated sampling frequency and representing the signal level at each sampling point; And correcting and calculating a time point at which the reproduction signal reaches the slice level based on the sampling frequency and the signal levels in the vicinity of the indicated slice level, and between time points at which the reproduction signal reaches the slice level. Jitter calculating means for calculating each time width, calculating a jitter component of a reproduction signal based on the respective time period, and finally controlling the reproduction measurements based on the jitter component.

The recording and / or reproducing system of the optical disc converts the reproduction signal of the optical disc into digital data at the indicated sampling frequency, corrects and calculates the time point at which the reproduction signal reaches the slice level, and calculates the jitter component of the reproduction signal. Calculates, and also takes into account the jitter component and performs feedback control on regeneration measurements.

Regarding one embodiment of the present invention, a method of reproducing an optical disc has the following characteristics: reproducing an optical disc in which digital data is stored according to the indicated modulation rule, and outputting data in accordance with the recording signals; Converting a reproduction signal in which digital data according to the indicated modulation rule is stored, into digital data sampled at the indicated sampling frequency and representing signal levels at each sampling point; Correcting and calculating a time point at which the reproduction signal reaches the slice level based on the sampling frequency and the signal levels in the vicinity of the indicated slice level; Calculate each time width between time points at which the playback signal reaches the slice level; Calculate a jitter component of a reproduction signal based on the respective time periods; The regenerative measurements are controlled based on the jitter component.

In the reproduction method of an optical disc, this converts the reproduction signal of the optical disc into digital data at the indicated sampling frequency, corrects and calculates the time point at which the reproduction signal reaches the slice level, calculates the jitter component of the reproduction signal, And perform feedback control for reproducing measurements based on the jitter component.

The measurement device for the characteristics of the optical pickup (hereinafter referred to as "characteristic test device") overhauls the characteristics of the optical pickup used in the optical disk driver. Such a characteristic test device is adopted in the specification test of the optical pickup or the study of the optical pickup characteristics: for example, it is adopted in the shipment test or the acceptance test of the optical pickup.

The foregoing description of the preferred embodiments of the invention has been presented for the purposes of illustration and description, and is not intended to be exhaustive or to limit the invention to the precise form described herein. With regard to the above learning contents, obvious modifications or variations will be apparent to those skilled in the art. All such modifications and variations are considered by the inventors in their entirety and fall within the scope of the invention as determined by the appended claims when interpreted in accordance with the scope fairly fairly legally imposed.

1 is a block diagram illustrating the application of an embodiment of the invention that is a measurement device for the characteristics of an optical pickup.

2 shows an example of a photo detector mounted to an optical pickup as a test object of the measuring device for the characteristics of the optical pickup.

3 is a flow chart illustrating the processing contents of the measuring device for the characteristics of the optical pickup.

Fig. 4 is a waveform diagram illustrating the processing contents of the measuring device for the characteristics of the optical pickup.

Fig. 5 is a waveform diagram illustrating the processing contents of the measuring device for the characteristics of the optical pickup.

6 is a flow chart illustrating the processing contents of the measuring device for the characteristics of the optical pickup.

FIG. 7 is a waveform diagram illustrating RF signals using a known binarized optical disc drive. FIG.

8 is a waveform diagram illustrating a measuring method of a known jitter measuring device.

9 is a waveform diagram illustrating a measuring method of a known jitter measuring device.

10 is a waveform diagram illustrating a measuring method of a known jitter measuring device.

Explanation of symbols on the main parts of the drawings

1: characteristic test device 2: optical pickup

3: test bench 4: matrix circuit

5: servo control circuit 7: memory

6: analog / digital conversion circuit 8: computer

Claims (12)

A method of measuring jitter in pulse width modulated signals that have been previously recorded on and reproduced from an optical disk in units of periods: Detecting a periodic signal reproduced from the optical disk using an optical pickup; Sampling the periodic signal at a predetermined sampling interval to define sampling points, and generating sample data corresponding to the signal level of the periodic signal at each of the sampling points thereto; Calculating a time width corresponding to a time interval wherein the signal level exceeds a slice level, wherein the time width is: Calculate a first time point at which the signal level first exceeds the slice level by interpolating between a sampling point that first exceeds the slice level and a previous sampling point; Calculate a second time point at which the signal level first falls below the slice level subsequent to the first time point by interpolating between a sampling point last exceeding the slice level and a next sampling point; Calculate a first time interval corresponding to the time between the first time point and the sampling point that first exceeds the slice level; Calculate a second time interval corresponding to a time between the sampling point first exceeding the slice level and the sampling point last exceeding the slice level; Calculate a third time interval corresponding to the time between the second time point and the sampling point last exceeding the slice level; The time width calculation step, calculated by adding the first, second, and third time intervals to calculate the time width; And Calculating a jitter measurement based on a difference between the calculated time span and a periodic window corresponding to a recorded theoretical time span of the periodic signal. The method of claim 1, Detecting a peak level of the sampled periodic signal; And Calculating the slice level based on the peak level. The method of claim 2, The peak level is based on an absolute value of a maximum level and a minimum level of the sampled periodic signal. The method of claim 3, wherein The peak level should exceed one quarter of the theoretical signal level value for the periodic signal. The method of claim 3, wherein Wherein the peak level should be maintained for a time interval greater than one half of the minimum periodic window corresponding to the minimum theoretical time width of the periodic signal recorded. The method of claim 1, Calculating the asymmetry value for the regenerative periodic signal by detecting and comparing the peak value for each period of the periodic signal. A device for measuring jitter in pulse width modulated signals that have been previously recorded on and reproduced from an optical disk in units of periods: An optical pickup for detecting a periodic signal reproduced from the optical disk; An analog-to-digital converter for sampling the periodic signal at a predetermined sampling interval to define sampling points, thereby generating sampling data corresponding to the signal level of the periodic signal at each of the sampling points; And Arithmetic processing means for calculating a time width corresponding to a time interval at which the signal level exceeds a slice level, wherein the time width is: Calculate a first time point at which the signal level first exceeds the slice level by interpolating between a sampling point that first exceeds the slice level and a previous sampling point; By interpolating between a sampling point last exceeding the slice level and a next sampling point, calculating a second time point at which the signal level first falls below the slice level subsequent to the first time point, Calculate a first time interval corresponding to the time between the first time point and the sampling point that first exceeds the slice level; Calculate a second time interval corresponding to a time between the sampling point first exceeding the slice level and the sampling point last exceeding the slice level; Calculate a third time interval corresponding to a time between the second time point and the sampling point last exceeding the slice level; Calculated by adding the first, second and third time intervals to calculate the time span, And said calculation processing means further calculates a jitter measurement based on a difference between said calculated time duration and a periodic window corresponding to a recorded theoretical time duration of said periodic signal. The method of claim 7, wherein The computing processing means further detects a peak level of the sampled periodic signal and calculates the slice level based on the peak level. The method of claim 8, The peak level is based on an absolute value of a maximum level and a minimum level of the sampled periodic signal. The method of claim 9, And the peak level should exceed one quarter of the theoretical signal level value for the periodic signal. The method of claim 9, The peak level should be maintained for a time interval that is greater than one half of the minimum periodic window corresponding to the minimum theoretical time width of the periodic signal recorded. The method of claim 7, wherein And the arithmetic processing means calculates an asymmetry value for the reproduction periodic signal by detecting and comparing a peak value for each period of the periodic signal.