JPH03224180A - Information recorder - Google Patents

Abstract

PURPOSE:To improve versatility by differentiating a detection signal corresponding to light reflected from a recording medium, computing the AND of a pulse signal obtained by comparing a prescribed value and a recording signal and deciding the existence of abnormality with the aid of comparing the AND and the recording signal. CONSTITUTION:An optical pickup 12 and an RF amplifier circuit 14 detect the light reflected by the recording medium 11 of a light beam and output the detection signal corresponding to the reflected light. A differentiation circuit 16 differentiates a reflected light signal outputted by the amplifier circuit 14 and outputs it to a comparison circuit 17. The circuit 17 compares the differenciated signal outputted by the differentiation circuit 16 with a signal having a prescribed value and outputs a rectangular pulse signal to an AND circuit 18. The circuit 18 computes the AND of the rectangular pulse signal and the recording signal. Then, a counting circuit 19 compares the AND with the recording signal and judges the existence of a recording defect. Thus, the need of a drastic change is eliminated with respect to the change of the recording medium 11 or the like and the versatility is improved.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an information recording device that optically records information, and more specifically, detects reflected light reflected from a medium during information recording and detects reflected light from a medium. The present invention relates to an information recording device that determines whether there is a recording defect.

(Prior art) As a conventional information recording device, Japanese Patent Application Laid-Open No. 61-13492
Those described in Publication No. 9 or Japanese Unexamined Patent Publication No. 61-278149 are known. For example, the latter JP-A-61
The recording device described in Japanese Patent No. 276149 records information by irradiating a perpendicularly magnetized medium with a light beam, and
The reflected light of this light beam from the perpendicularly magnetized medium is detected by an analyzer, converted into a signal with a potential corresponding to the amplitude of the reflected light, and the waveform of this signal is compared with the waveform of the reference signal to check for recording defects. Discern.

(Problem to be Solved by the Invention) However, in the recording device of JP-A-61-276149 mentioned above, the reference signal obtained by waveform shaping the signal waveform representing the amplitude of the reflected light and the recording signal is In order to determine whether there is a recording defect by comparing the However, when changing the medium, it is necessary to replace the waveform shaping circuit that generates the reference signal, resulting in a lack of versatility. In particular, in the case of recording media that record information through changes in reflectance, the amplitude of the signal changes significantly when the reflectance changes, so the above-mentioned problem is also significant, and a solution to this problem has been desired.

The present invention has been made in view of the above-mentioned problems, and aims to provide an information recording device that does not require major modification even when the recording medium changes, and has great versatility.

(Means for Solving the Problems) The present invention provides an information recording apparatus that records information on a recording medium by irradiating a light beam onto the recording medium based on a recording signal, in which reflected light of the light beam reflected by the recording medium a reflected light detection means for detecting the reflected light and outputting a detection signal corresponding to the reflected light; a differentiating circuit for differentiating the detection signal outputted by the reflected light detecting means; a comparator circuit that outputs a pulse signal, an AND operation circuit that calculates the AND of the pulse signal output by this comparison circuit and the recording signal, and a comparison between the output signal of the AND operation circuit and the recording signal. The gist is to have a determination circuit that determines whether or not there is a recording defect.

(Function) The information recording device of the present invention differentiates a detection signal corresponding to reflected light from a recording medium, compares the differentiated signal with a predetermined value, and combines a pulse signal and a recording signal. is calculated, and this AND is compared with the recorded signal to determine whether there is an abnormality. Therefore, even if the amplitude of the detection signal changes due to a change in the reflection characteristics of the medium due to a change in material, etc., the effect on the differential signal is small, and this can be countered by adjusting the time constant of the differentiator circuit, etc. This gives you great versatility.

(Example) In FIG. 1, 11 is a recording medium;
consists of a so-called optical disc of the light reflection type. In the recording medium 11, pits P (see Fig. 2) with low light reflectance are formed in the track by a laser beam R (see Fig. 2) irradiated from the optical pickup 12, and information is recorded by changes in the light reflectance. do.

Although not shown clearly in the figure, the optical pickup 12 includes a light emitting element such as a semiconductor laser, a light receiving element such as a photodiode, a collimator lens, etc., and is supported so as to be movable in the radial direction of the recording medium 11 by a transport mechanism having a motor etc. has been done. In this optical pickup 12, a light emitting element is connected to a laser drive circuit 13, a light receiving element is connected to an RF amplifier circuit 14, a motor of a transport mechanism is connected to a servo circuit 15, and the light emitting element emits a laser beam R toward a recording medium 11. Recording medium 1
A bit P is formed in 1, the light receiving element receives the reflected light of the laser beam R reflected by the recording medium 11, and converts it into an electric signal, and the transport mechanism is controlled by the servo circuit 15. As shown in FIG. 2, the laser beam R changes in light intensity in response to a recording signal W input to a laser drive circuit 13, which will be described later, and has a large light intensity during a high-level period when the recording signal W is at a high level. It has a relatively high light intensity period) and a small light intensity during a low level period. The bit P of the recording medium 11 is formed with a time delay with respect to the period of high light intensity of the laser beam R, and before and after the pit P there is a phase delay τ1.
There is τ2.

The laser drive circuit 13 generates a pulse signal representing information (hereinafter referred to as
W (referred to as a recording signal) (see FIG. 2) is manually input, and the light emitting element is driven based on this recording signal W. As is clear from FIG. 2, this laser drive circuit 13 drives the optical pickup 12 so that the laser beam R has a large amount of light during the high level period of the recording signal W. The RF amplifier circuit 14 performs high-frequency amplification on the output signal of the light receiving element and outputs a reflected light signal V (see FIG. 2) corresponding to the amount of reflected light incident on the light receiving element to the differentiating circuit 16. The reflected light signal V output from this RF amplifier circuit 14 is transmitted to the area I1. on the left side of FIG. : If the pit P is formed accurately, it will exhibit a waveform with a maximum value (positive peak value) near the front of the pit P and a minimum value (negative peak value) at the rear end, and the pit P The value decreases rapidly before and after. In FIG. 2, signals and pits that should exist under normal conditions are indicated by broken lines.

The differentiating circuit 16 is configured such that its time constant can be adjusted, and differentiates the reflected light signal (2) output from the RF amplifier circuit 14 and outputs the differential signal V shown in FIG. 2 to the comparing circuit 17. The differential signal V output from the differential circuit 16 has a negative peak value before and after the pit P, corresponding to the sudden decrease portion of the reflected light signal V described above. The comparison circuit 17 compares the differential signal * outputted by the differentiating circuit 16 with a signal C having a predetermined value, and outputs a rectangular pulse signal S having a high potential H to the AND circuit 18 when the signal C is larger than the differential signal V. . The AND circuit 18 inputs the above-mentioned recording signal W together with the rectangular pulse signal S, calculates the logical product of these signals S and W, and outputs the pulse signal A to the counting circuit 19.

The counting circuit 19 inputs the rectangular pulse signal A output from the AND circuit 18 to the down terminal and the above-mentioned recording signal W to the up terminal, subtracts the number of pulses of the rectangular pulse signal A, and adds the number of pulses of the recording signal W. do. As will be described later, the count value of this counting circuit 19 represents the number of recording defects.

In this embodiment, the optical pickup 12 and R
The F amplifier circuit 14 serves as the reflected light detection means, and the AND circuit 18 serves as the reflected light detection means.
corresponds to an AND operation circuit, and the counting circuit 19 corresponds to a determination circuit.

The information recording device of this embodiment rotates the recording medium 11 at a constant speed, and the light emitting element of the optical pickup 12 irradiates the recording medium 11 with a laser beam R based on the recording signal W to form pits P. The reflected light reflected by the recording medium 11 is received by the light receiving element of the optical pickup 12 and converted into an electrical signal, and this electrical signal is input to the RF amplifier circuit 14 and amplified at high frequency.

Here, if the recording is performed normally, that is, if prescribed pits corresponding to the pulse width of the recording signal W are formed on the recording medium 11, the RF
Since the amplifier circuit 14 outputs a reflected light signal ■ having a waveform having positive and negative peak values before and after the pit P, the differentiating circuit 16 outputs a differential signal * having a waveform having negative peak values before and after the pit P, The signal S output by the comparator circuit 17 generates two pulses in one cycle of the recording signal W, and one pulse occurs during the high level period of the recording signal W. Therefore, the AND circuit 18 outputs the pulse signal A having the same period as the recording signal W, and the AND circuit 18 outputs the pulse signal A.
Since the number of pulses of the recording signal W becomes equal to the number of pulses of the recording signal W, the count value of the counting circuit 19 also becomes zero, and this counting circuit 19
It is determined from the output signal that there is no recording defect.

On the other hand, if the pit P is not formed on the recording medium 11 even though the laser beam R has a specified light intensity, that is, if a recording defect occurs, the optical pickup 1
The laser beam R irradiated onto the recording medium 11 from the light emitting element 2 is reflected with a high light reflectance and enters the light receiving element, and as shown in area I+ in FIG. The optical signal V has substantially the same waveform as the recording signal W. Therefore, the differentiating circuit 16 outputs a signal ■ that generates one pulse during the low level period of the recording signal W in one period of the recording signal W, and the output signal A of the AND circuit 18 does not generate a pulse, and the recording signal W The number of pulses of the AND circuit 18 corresponds to the number of recording defects, and the count value of the counting circuit 19 represents the number of recording defects. That is,
A recording failure is determined based on the count value of the counting circuit 19.

Similarly, as shown in area III in FIG. 2, if the light intensity of the laser beam R is smaller than the specified value and a defect occurs in which a part of the pit P is missing, the amount of reflected light also decreases and the laser beam At the beginning of the high light intensity period of R, the time change rate of the signal V waveform of the RF amplifier circuit 14 is also small, and the differential circuit 16
The differential signal (2) outputted by the recording signal W also generates only one pulse during the low level period of the recording signal W in one period of the recording signal W. Therefore, as in the case where the recording failure described above occurs, the signal A output from the AND circuit 18 is 1 of the recording signal W.
There is no pulse in the cycle, and a recording failure is determined based on the count value of the counting circuit 19.

In this information recording device, even if information is recorded on the recording medium 11 having different reflection characteristics, the RF
The output signal V of the amplifier circuit 14 is differentiated by a differentiating circuit 16, and it is determined whether the reflected light is normal or not based on the differential signal V outputted by the differentiating circuit 16, that is, the temporal change in the reflected light. The influence of changes in the amount of reflected light due to changes in the amount of reflected light, etc. is not small, and recording defects of various recording media 11 can be determined by adjusting the time constant of the differentiating circuit 16, resulting in high versatility.

In addition, in the embodiment described above, the recording signal W,
An example of an up-down counting circuit 19 is shown in which the output signal A of the AND circuit 18 is manually input to the down terminal, but the recording signal W
It is also possible to count the output signal A of the AND circuit 18 by separate counting circuits, and compare, for example, divide, the counts of these counting circuits to determine the defective rate.

(Effects of the Invention) As explained above, according to the information recording device according to the present invention, even when the reflection characteristics of the recording medium change, that is, when recording information on recording media with different reflection characteristics, the differential Recording defects can be determined by adjusting the time constant of the circuit, etc., and high versatility can be achieved.

[Brief explanation of drawings]

1 and 2 show an information recording device according to an embodiment of the present invention, with FIG. 1 being a block diagram and FIG. 2 being a timing chart. DESCRIPTION OF SYMBOLS 11... Recording medium, 12... Optical pickup (reflected light detection means), 14... RF amplification circuit (reflected light detection means), 16... Differentiation circuit, 17... Comparison circuit, 18
...AND circuit (logical product calculation circuit), 19...counting circuit (judgment circuit), A...pulse signal (logical product), R
... Laser beam, S... Pulse signal, ■... Reflected light signal (detection signal), ■... Differential signal, W... Recording signal.

Claims (1)

[Scope of Claims] An information recording device that records information on a recording medium by irradiating a light beam onto the recording medium based on a recording signal, which detects the reflected light of the light beam reflected by the recording medium and converts it into reflected light. a differentiating circuit for differentiating the detection signal output by the reflected light detecting means; and a comparison circuit for comparing the signal output by the differentiating circuit with a predetermined value and outputting a pulse signal. a circuit, an AND operation circuit that calculates the AND of the pulse signal outputted by the comparison circuit and the recording signal, and a logical AND operation circuit that compares the output signal of the AND operation circuit with the recording signal to determine whether or not there is a recording defect. An information recording device comprising: a determination circuit for making a determination;