JPS61134928A - Signal detection - Google Patents

Abstract

PURPOSE:To discriminate accurately a recorded area and an unrecorded area of a medium from each other by deciding the area, where the counted number of output pulses of a comparing circuit is equal to or larger than a prescribed value, as a data recorded part when an envelope signal having a voltage higher than a reference voltage is inputted. CONSTITUTION:A reproduced signal (1) is integrated, and an envelope signal (2) is outputted to a comparing circuit 8. A comparator 14 in the comparing circuit 8 compares this signal (2) with a reference voltage Vrelf set to an about half of a peak voltage Vp.p of the reproduced signal (1), and the comparator 14 transmits an output (3) to a terminal R of a counter circuit 10 while the envelope signal (2) exceeding the reference voltage -Vrelf is inputted. Meanwhile, a comparator 15 in the comparing circuit 9 compares the reproduced signal (1) with a reference voltage Vrelf 2 set to an about 1/3 of the peak voltage Vp.p of the reproduced signal (1) and pulses both of positive and negative edges of an output signal (pulse waveform) exceeding the reference voltage Vrelf2 and transmits these pulses to a terminal C of the counter circuit 10. A counter 17 in the counter circuit 10 stops the counting operation when 8 pulses of an output (4) of the comparing circuit 9 which is inputted when the output (3) of the comparator 14 is turned on.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a write-once optical storage device that optically records/reproduces data, and particularly relates to a write-once optical storage device that optically records/reproduces data. This invention relates to a signal detection method for reliable determination.

One type of optical storage device that is expected to serve as a large-capacity external storage device for information processing equipment is the write-once optical storage device, which is capable of recording and reproducing data (however, data cannot be rewritten). The write-once medium 1 is formed as shown in FIG.

That is, the write-once medium 1 has a recording layer formed on a transparent substrate a. This recording layer consists of a preformat section C and a group (groove) section d.

The preformer 7 part C and the group (groove) part d are.

It is formed on a transparent substrate a using a stamping technique.

A recording layer is deposited thereon.

Note that FIG. 4(A) is a schematic diagram of the write-once medium 1, and FIG. 4(B) is a schematic diagram of the write-once medium 1.
is a top view of the write-once medium 1, and FIG. 4(C) is a top view of the write-once medium 1.
The sectional view and FIG. 4(D) show the group of write once medium 1 (
The data recording situation in groove) section d is shown.

Data is recorded on the write-once medium 1 as described above.

The information in the glyph format section C is read and positioned to the target position, and the light emitted from the semiconductor laser 4 is focused by an objective lens 6 etc. onto the group (groove) section d, which is positioned 1, to form a light beam, and this light beam is irradiated. By the irradiation heat reaction of the recording layer, pits (holes) as shown in FIG. 4(D) are made.
Record.

Also, tracking on the group (groove) portion d during recording is as follows.

The group (groove) portion d of the rotating write-once medium 1 is detected by the detector 3, and tracking onto the group (iia groove) portion d is performed based on the obtained optical pickup control signal.

Furthermore, the detector 3 detects the incident reflected light from the write-once medium 1 through the deflection prism 5, and reads the recorded data. Incidentally, FIG. 5 shows a schematic diagram of the configuration of the optical head 2. As shown in FIG.

In general, the interval between group (groove) parts d is 2 μm or less, and the size of pits (holes) is very small, about 1 μm. ) There is a level relationship as shown in FIG. 6 with the level when the data of section d is read.

In general, data recording on the group (groove) part d is performed by creating pits (holes) by the irradiation heat reaction already in the recording layer as described above, so it is possible to accurately distinguish between data recorded areas and unrecorded areas. need to be determined.

There is a need for a signal detection method that can more reliably detect the discrimination between data-recorded areas and unrecorded areas and that can be realized with a simple circuit configuration.

[Prior art and problems to be solved by the invention] FIG. 7 is a diagram of a conventional signal detection system, in which (A) shows a block diagram and (B) shows a signal detection waveform.

In the conventional signal detection method, the reproduced output signal ■ which the detector 3 detects and outputs the reflected light from the group l) part d is the seventh
The waveform is shown in region (1) of FIG. 3B, and the output after integrating this in the integrating circuit 7 (which is an envelope signal of the reproduced output signal ■ and shown by a one-dot line) becomes a signal ■.

This signal ■ is compared with the reference voltage Vrefl by the comparator 8, and if a voltage equal to or higher than the reference voltage Vref1 is obtained.

The signal ■ is output, and if the voltage is lower than the reference voltage Vrefl, the signal ■ is not output. Note that the reference voltage Vrefl is usually approximately 1/of the voltage Vp, p at the peak of the reproduced output signal ■.
It is set to about 2.

The area (1) in FIG. 7(CB) is the area where a voltage higher than the reference voltage Vref1 is obtained, that is, the data recorded area, and the area (2) in FIG. 7(B) is the area where the voltage higher than the reference voltage Vref1 is obtained. In the conventional signal detection method, a portion where only a voltage was obtained, that is, an unrecorded area, was determined by a discriminating section (not shown).

However, with such conventional signal detection methods.

If a defect or the like exists on the group (groove) portion d of the unrecorded area, the reproduced output signal ■ of the defect is a signal having the same peak output as that of the data recorded area (i.e., Fig. 7(B)).
(a) and (b)), and there was a problem in that it could be mistakenly detected as a signal from a recorded area.

[Problem that the invention seeks to solve]

The present invention aims to realize a new signal detection method that solves the above problems.

The problem consists of a signal envelope detection means whose output is turned on when the envelope value of the reproduced output signal is greater than a first predetermined voltage level, and a signal envelope detector whose output is turned on when the envelope value of the reproduced output signal is greater than a first predetermined voltage level; level pulse detection means for comparing and outputting a signal larger than the second voltage level as a pulse signal, and counting the number of pulses detected by the level pulse detection means, and counting when the envelope detection signal turns off. This problem is solved by the signal detection method according to the present invention, which includes a pulse counting means for resetting the pulse counting means, and determines a portion where the output of the pulse counting means exceeds a predetermined count value as a data-recorded portion.

[Effect]

That is, a second reference voltage of 1/3 potential of the peak voltage of the reproduced output signal is set, and when a reproduced output signal higher than this second reference voltage is input, the level pulse detection means 2 outputs a pulse signal, for example. A comparison circuit is provided, and the first reference voltage (
For example, when an envelope signal of the reproduced output signal is input which is equal to or higher than the reference voltage (1/2 potential of the peak voltage of the reproduced output signal).

By counting the duration width of the output pulses of the comparison circuit and determining the area for which the count value is greater than a predetermined value as the data recorded area, recorded areas and unrecorded areas can be more reliably determined with a simple circuit configuration. This makes it possible to determine the recording area.

〔Example〕

The gist of the present invention will be specifically explained below with reference to embodiments shown in FIGS. 1 to 3.

FIG. 1 is a block diagram showing an embodiment of the signal detection method according to the present invention, FIG. 2 is an example of the specific circuit configuration of FIG. 1, and FIG. 3 is a block diagram showing an embodiment of the signal detection method according to the present invention. Time chart diagrams are shown respectively. The same reference numerals indicate the same objects throughout the figures.

Next, the operation of this embodiment will be explained.

The reproduced signal (2) is amplified by the differential amplifier 11 in the integrating circuit 7, and the amplified positive and negative signals are full-wave rectified by the rectifier circuit 12. The rectification operation is performed by a 21-wire transistor with a common emitter, capacitors CI and C2, and resistors R1, R2.

The integrating circuit section for detecting the envelope of the reproduced signal ■ is composed of an emitter resistor R3 and a capacitor C3 connected to the emitter of the rectifier circuit 12, and has a time constant of r.
= C3R3 is obtained. Here, τ is a value determined from the frequency of the reproduced signal ■, and is 1 of the highest frequency of the reproduced signal ■.
Select around 1/20 to 1/20.

The integrated signal is outputted to the comparison circuit 8 via the buffer circuit 13 as an envelope signal (2).

The buffer circuit 13 is a circuit having high input impedance, and is used to eliminate the influence of the comparison circuit 8 on the integration circuit 7.

In the comparator 14 in the comparator circuit 8, the envelope signal ■ inputted from the six integrating circuits 7 is set to, for example, about 1/2 of the peak voltage VP, I) of the reproduced signal ■ (the voltage Vcc is set by the variable resistor VRI) as a standard. When compared with the voltage Vref 1, while the envelope signal ■ which exceeds the reference voltage Vrefl is being input, the output ■ is turned on and sent to the terminal R of the counter circuit 10. Furthermore, the comparator 14 is.

A general low-speed comparator (for example, if the comparable signal frequency is IM)
Hz).

On the other hand, the comparator 15 in the comparator circuit 9 outputs 2, for example, the reproduced signal
Set to about 1/3 of the peak voltage vp, p (voltage Vcc
The reproduced signal ■ is compared with the reference voltage Vref2 (set by the variable resistor VR2), and both positive and negative edges of the output signal (pulse waveform) exceeding the reference voltage Vref2 are converted into pulses by the pulse circuit 1.
6, it is normally pulsed and sent to terminal C of the counter circuit 10.

The pulsing circuit 16 includes an inverter section for the purpose of signal delay and an exclusive OR circuit.

The comparator 15 is a high-speed comparator (for example, the comparable signal frequency is about 20 MHz), and has a sufficient speed to respond to the highest frequency of the reproduced signal (2).

The counter 17 in the counter circuit 10 is a binary counter, and when it counts 8 pulses of the output ■ of the comparator circuit 9 that is input when the output ■ of the comparator 14 is on, the count value of the 8th pulse is sent to the reset terminal through the inverter 18. The counter 17 is configured to return to its original state and stop the counting operation of the counter 17.

In other words, in this embodiment, if the envelope signal ■ exceeds the specified level and the reproduction signal ■ does not count 8 pulses, it is determined that the area is a recorded area (the determination is made based on the count value of the 8th pulse). (A judgment circuit (not shown) determines whether the receiver is receiving the signal) is not possible.

Therefore, such a signal detection method can be used satisfactorily as long as there are not many defects in the medium 1 at the stem end.

〔Effect of the invention〕

According to the present invention as described above, it is possible to accurately discriminate between recorded areas and unrecorded areas of a medium without being affected by defects in the medium, and moreover, with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a signal detection method according to the present invention. FIG. 2 shows an example of the specific circuit configuration of FIG. 1. FIG. 3 is a time chart diagram of the signal detection method according to the present invention. FIG. 4(A) is a schematic diagram of the write-once medium 1. FIG. 4(B) is a top view of the write-once medium 1. FIG. 4(C) is a sectional view of the write-once medium 1. FIG. 4(D) shows the state of data recording in the group (groove) portion of the write-once medium 1. FIG. 5 is a schematic diagram of the configuration of the optical head. FIG. 6 is a waveform diagram for reading a medium. FIG. 7 is a diagram of a conventional signal detection method, where (A) is a block diagram and (B) is a signal detection waveform diagram. are shown respectively. In fig. 1 is the medium, 2 is the optical head. 3 is a detector, 4 is a semiconductor laser. 5 is a deflection prism, and 6 is an objective lens. 7 is an integration circuit, 8.9 is a comparison circuit. 10 is a counter circuit, and 11 is a differential amplifier. 12 is a rectifier circuit, and 13 is a buffer. 14 and 15 are comparators, and 16 is a pulse generator. 17 is a counter, 1B is an inverter. are shown respectively. L---J

Claims (1)

[Claims] a reproduction output section that reproduces and outputs data read from a medium for optically recording data; and whether the reproduction output signal from the reproduction output section is a reproduction output signal of a data-recorded portion or a reproduction output signal of a data-unrecorded portion. A storage device comprising: a signal envelope detection means whose output is turned on when the envelope value of the reproduction output signal is larger than a first predetermined voltage level; level pulse detection means for comparing the outputs of the portions at a second predetermined voltage level and outputting a signal larger than the second voltage level as a pulse signal; and counting the number of pulses detected by the level pulse detection means; A pulse counting means for resetting a count when the envelope detection signal is turned off, and a portion where the output of the pulse counting means exceeds a predetermined count value is determined to be a data-recorded portion. Detection method.