JPH0369037A - Automatic detector for optical disk preformat part - 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 relates to an optical disc preformat part automatic detection device that automatically detects the position of a preformat part of an optical disc.

<Prior Art> As shown in FIG. 4, an optical disc has a glyph format at the beginning of each sector that indicates information about that sector. This preformat is formed to have a higher reflectance than a normal portion (a portion other than the preformat portion).

By the way, when inspecting the quality of optical discs, reflectance and scratches are checked, but in this inspection, the preformatted portion is excluded from the measurement target. In order to exclude the preformat part from the measurement target, it is necessary to correctly detect the position of the glyph format.

<Problems to be Solved by the Invention> The preformat position is usually detected based on the difference in reflectance (there is a clear difference in reflectance between the preformat part and the data part), but it Indistinguishable and possible misidentification. For this reason, after the inspection, reconfirmation is required using an oscilloscope, which is very time-consuming.

SUMMARY OF THE INVENTION An object of the present invention is to provide a detection device that automatically detects the preformat position of an optical disc.

Means for Solving the Problems> In order to achieve such an object, the present invention provides a spindle motor that is connected to a spindle motor that rotates an optical disk, and that combines pulses generated at the reference position of the disk and pulses generated in response to rotation. an encoder that outputs an output; an optical head that detects a reflected beam from an optical disk and outputs an electrical signal according to the intensity of the reflected beam; and a binarization means that binarizes the electrical signal from the optical head. position data reading means for receiving output pulses from the encoder and counting pulses generated in response to rotation after a pulse is generated at a reference position of the disk; and position data reading means for reading every time a pulse is output from the binarization means. storing the value of the position data reading means, and
An optical disc characterized in that it is equipped with a memory for storing other necessary data, a processing means having a function of determining a preformat position according to the following procedure, and a control means for performing necessary control on each of the above parts. Preformat section automatic detection device.

Note: For each actually measured position data, the logical preformat position of each sector is calculated from the number of sectors on the optical disc using its own position data as a reference.

(2) Next, a standard surface difference is determined from the difference between this logical preformat position data and the actually measured glyph format position data.

■For each position data, calculate the standard deviation as described above.

(2) Extract the minimum one among the obtained a standard deviations, and find the logical preformat position from the position data in that case.

(2) The value closest to the spindle reference position in the obtained logical preformat position data string is set as the final preformat position offset.

Effects> The present invention binarizes the difference in reflectance of an optical disk and obtains its position as data corresponding to the angle from the reference position of the spindle. Based on the measurement data, paying attention to the regularity of the preformat, the processing means calculates the standard deviation from all the position data, and extracts the case where the standard deviation is the minimum.

Furthermore, in that case, the data closest to the spindle reference position (i also has a small angle) is selected as the most reliable preformat position offset.

In this way, a logical preformat position is determined based on the actually measured position data.

<Example> The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of essential parts of an embodiment of an optical disc preformat portion automatic detection device according to the present invention. In the figure, 1 is an optical disk, and 2 is a spindle motor for rotating the optical disk.

3 is an encoder connected to the rotating shaft of the spindle motor, which outputs a pulse (referred to as a Z-phase pulse) once during one revolution of the disk, and a predetermined number of pulses between Z-phase pulses and the next Z-phase pulse. It is designed to generate a pulse (referred to as A-phase S pulse). Reference numeral 5 denotes an optical head section, which is comprised of an optical head that emits the light beam 4 and an amplifier that converts the reflected beam from the optical disk into an electrical signal and outputs it. 6
is a slide table that can move the optical head section in the radial direction of the optical disk.

10 is a processing device that receives signals from the encoder 3 and the optical head section 5 and automatically obtains a preformat section;
Value conversion means 11, position data reading means 12, memory 13
, processing means 14, control means 15, and a bus 16 for interconnecting these parts and transmitting data.

The binarization means 11 converts the analog signal corresponding to the reflected beam intensity given from the optical head section into 2i signals using a certain threshold value. Since the preformat portion has a higher reflectance than other portions and a reflected beam intensity is greater, a 21 pulse corresponding to the preformat position can be obtained.

The position data reading means 12 counts the A-phase pulses after the two-phase pulse is generated by the encoder 3, and the count value is position data (angle data) corresponding to the rotational position of the optical disk.

The position data obtained by the position data reading means 12 is sequentially stored in the memory 13 at the timing of the rising edge of the output pulse of the binarizing means 11. That is, angle data for each appearance of the preformat section is stored.

The processing means 14 is a circuit that determines a preformat position based on each position data stored in the memory 13, and has a function of determining the preformat position according to the following steps (1) to (2).

■For each actually measured position data, use your own position data as a reference, and calculate the logical preformat position of each sector from the number of sectors on the optical disk. (sometimes called columns).

(2) Next, the standard deviation is calculated from the difference between this logical preformat position data and the actually measured preformat position data.

■For multi-position data, calculate the standard deviation as described above.

(2) Extract the minimum standard deviation among the standard deviations obtained, and calculate the logical preformat position from the position data in that case.

(2) Among the obtained logical preformat position data string, the value closest to the spindle reference position (the position at the time of Z-phase pulse generation) (the smallest angle data) is set as the final preformat position data.

The control means 15 controls each part as appropriate, and each time a pulse is output from the binarization means 11, the output of the position data reading means 12 is successively stored in the memory 13, and when the data is complete, it is Necessary controls such as activating the processing means 14 and executing processing for determining the preformat position are performed.

The operation in such a configuration will be explained next.

The spindle motor 2 is driven to rotate the optical disk 1, and the reflected beam obtained from the optical head section 2 is binarized by the binarization means 11. During one rotation of the disk, the binarization means 1
The output of the position data reading means 12 is read at each rising edge of the pulse output from the position data reading means 12 and stored in the memory 13. Even within one preformat section, the reflected beam intensity changes and the 21 straightening pulse occurs multiple times, so the
), a plurality of position data are measured for a part of one preformat (1 rotation, 2 pieces of data,
That is, dl, d2, d3, . . . dk are measured>, and these position data are stored in the memory 3. Thereafter, the processing means 14 is activated to execute the next process. The flow shown in FIG. 3 is a processing operation flow by the processing means.

Using any one of the preformat position data stored in the memory as a reference, a logical preformat position d... is determined by the following relationship.

J d, j=d, +360Xj /S However, i=1.2. ,,,k J=1.2. ,,,S S is the number of sectors (preset).For example, take out the first data d1 and find the logical glyph format position 1lfdij as shown in (a> in Fig. 2) based on this. .

Each logical gid, j to shi(1/4)X (360/
The actual measured data closest to the logical value within the range (number of sectors) is selected. As shown in FIG. 2(b), the value is d' (where J=1.2.).

S).

The difference ft and a between each logical value dij and its corresponding data dJ is calculated according to the following equation.

In this way, the standard deviation is also obtained for the measured data after d2. This results in standard deviations (σ1.σ2
"" σk) is obtained.

Therefore, since the most reliable preformat position is the one where the standard deviation is the minimum among the k WA standard deviations, the logic is again calculated based on the position data (d,) where the standard deviation is the minimum Calculate the preformat position (preformat position data string). Among them, the smallest position data (angle data) from the spindle reference position (at the time of two-phase pulse generation) is determined as the position data to be obtained.

The preformat position determined as described above is used as follows. That is, a preformat partial erase signal is created based on the determined preformat position, and the influence of the preformat is removed by the preformat partial erase signal to measure the reflectance of the optical disk and the hot water side.

In the embodiment, the regularity is found using the standard deviation, but instead of using the standard deviation, the most reliable preformat position is determined by comparing the power spectrum at the number of sectors S using fast Fourier transform. You can also do it like this.

<Effects of the Invention> As described above in detail, the present invention has the following effects.

■There is no need for the operator to confirm the position of the glyph format, and there is no need to constantly monitor or operate the inspection device when inspecting optical disks.

■Measurement time has been shortened.

, (2) In the case of an equally divided preformat disk, the preformat position can be determined without depending on the number of sectors.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main parts of an embodiment of the automatic optical disk preformat detection device according to the present invention, FIG. 2 is a diagram showing the relationship between measured data and logical values, and FIG. 3 is the operation of the processing means. FIG. 4, which is a diagram showing the flow, is a conceptual diagram showing the preformat position of the disc. 1... Optical disk, 2... Spindle motor, 3.
... Encoder, 5... Optical head unit, 6... Slide table, 10... Processing device, 11... Binarization means, 12... Position data reading means, 13... Memory, 14... Processing means, 15... Control means, 16
···bus. 3 Figure Equal division preformat

Claims (1)

[Claims] An encoder connected to a spindle motor that rotates an optical disk and outputs pulses generated at a reference position of the disk and pulses generated in accordance with rotation; and an encoder that detects a reflected beam from the optical disk and detects the reflected beam. an optical head section that outputs an electrical signal according to the intensity; a binarization means that binarizes the electrical signal from the optical head section; position data reading means for counting pulses generated in accordance with the rotation after they have been generated; and storing a value of the position data reading means that is read every time a pulse is output from the binarization means;
An optical disc characterized in that it is equipped with a memory for storing other necessary data, a processing means having a function of determining a preformat position according to the following procedure, and a control means for performing necessary control on each of the above parts. Automatic preformat detection device. (1) For each actually measured position data, the logical preformat position of each sector is calculated from the number of sectors on the optical disc using its own position data as a reference. (2) Next, the standard deviation is determined from the difference between this logical preformat position data and the actually measured preformat position data. (3) For each position data, find the standard deviation as described above. (4) Extract the minimum standard deviation among the obtained standard deviations, and determine the logical preformat position from the position data in that case. (5) The value closest to the spindle reference position in the obtained logical preformat position data string is set as the final preformat position offset.