JPH0214435A - Method for controlling record of optical recording and reproducing medium - Google Patents

Abstract

PURPOSE:To stably control the actuator of a light pick-up by impressing a delay pulse to excessive components contained in an error signal from a photoelectric detector and supplying a control signal obtained after a sample-holding with a small time constant is applied and a removal is executed. CONSTITUTION:To a focusing servo control circuits Fs and a tracking servo control circuit Ts, deecting signals are fetched from a photoelectric detector 1, respectively, pulses are given through a one-shot multivibrator 3 to switches 41 and 42 based on the command of a CPU 2, a focus sample-hold circuit is composed of the switch 41, a resistor R1, a capacitor C1 and a buffer 51, and a tracking sample-hold circuit is composed of the switch 42, a resistor R2, a capacitor C2 and a buffer 52. To an abnormal and, simultaneously, excessive signal mixed in the error signal as the output of the laser beam is increased at the time of recording, the delay pulse is given to the switch of a tracking servo system. Thus, the actuator to mount the light pick-up can be stably controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention is directed to a focus servo system when recording (writing) information to an optical recording/reproducing medium (hereinafter abbreviated as "medium") such as a compact disk or a laser card. Also, under the action of the tracking servo, the control signal for controlling the actuator mounted on the optical pickup is prevented from being disturbed due to the high output light beam, thereby making the information pit diameter uniform and preventing the meandering of the information pit row. The present invention relates to a recording control method that can be applied to an optical recording/reproducing device and which aims to obtain linearity of recorded information tracks by preventing such problems.

``Prior art'' A beam emitted from a laser light source is focused by an optical system to form an optical spot, and information is written and arranged in bits on a medium.Usually, the beam emitted from a laser light source is focused using a diffraction grating. The central king beam spot is used for focusing and recording and reproducing information through an objective lens, and the two side spots formed by the sub beams on both sides of the king beam are focused onto a track and detected by a photoelectric detector. The side spots are detected and controlled by a servo system so that the photoelectric signals, that is, the amounts of light, from these side spots are equalized.

Therefore, when recording information in the form of bits, the laser light output is increased more than when reading, and once the information is written on the medium, it is a write-once type that cannot be erased.

To reproduce (read) the recorded information, the amount of light from the photoelectric detector is converted into voltage using the difference in brightness or darkness, that is, reflectance, between the medium and the information bits, and after A/1) conversion by the detection circuit, the PLL is used to The configuration is such that the signal is demodulated and processed by the CPU.

The focusing and tracking controls described above both use detection error signals during playback, but when recording information, the laser output is increased as described above, causing disturbances in the control signal and making control impossible. If the servo stops working, the servo action may become disconnected, or even if the servo does not come off, the writing bit diameter may become uneven or the bit string may meander.

"Problem to be Solved by the Invention" However, the present invention solves the problem by preventing the transmission of an abnormal signal due to an increase in laser light output even under the action of focusing and tracking servo when recording information.
The present invention aims to provide a method that can stably control an actuator equipped with an optical pickup.

"Means for Solving the Problem" When writing information by irradiating the medium with the above-mentioned high-power laser beam, the passage of excessive and abnormal r and H signals is prevented even under the action of focusing and tracking servos. In order to prevent this, a switch is provided in each of the focusing and tracking control circuits, and by opening the switch using a delay pulse, a normal signal voltage is applied to the actuator.

An embodiment of the present invention will be described below with reference to the drawings.

``Embodiment'' In FIG. 1, F$, indicated by the large arrow, takes out the husband detection signal from the photoelectric detector 1 to the focusing servo control circuit and Ts to the tracking servo control circuit. 2 is a circuit configuration diagram implementing the invention configured such that pulses are applied to switches 41 and 42 via the one-shot multivibrator 3, and FIG. 2 shows the terminals of the switch 41 of the focus servo circuit ps of FIG. FIG. 3 is a waveform graph at the terminal of the switch 42 of the tracking servo circuit T3 in FIG.

First, in FIG. 1, the focus sample hold circuit is connected to switch 41. It is composed of a resistor R, a capacitor q-, and a buffer 51, and the output terminal of the error amplifier 31, that is, the input terminal of the above-mentioned switch, receives a write pulse PW of pulse width An excessively steep voltage is applied at the edge of the terminal a as shown in the figure (b). - In view of the fact that the laser light output increases at the time of input, the stage before the error amplifier 31, that is, the I/V converter 21
At the output terminal of the photoelectric detector 1, the signal A of the photoelectric detector 1 is clagged by the IC power supply voltage, and the output of the error amplifier becomes zero and H.

Furthermore, since the main beams A and B remain on the information bit even after the write operation is completed, the error 2 signal containing the information bit component is output. A control signal as shown in Figure 2 (c) is obtained and applied to the actuator. After all, the switch cuts off an abnormally large error signal during recording and supplies only a signal that can stably drive the actuator.

-1f, -On the other hand,) the racking sample hold circuit is shown by the thick arrow Ts in FIG. 1 as the switch 42. It is composed of a resistor R2, a capacitor C2, and a buffer 52, and the output terminal of the error amplifier 32, that is, the input terminal e of the above-mentioned switch, is supplied with a write delay pulse PD having a pulse width x2 applied from the one-shot multivibrator 3 to the terminal d. A voltage with a waveform as shown in Figure 3 (B), which corresponds to a voltage with a waveform as shown in Figure 3 (A) with an extended pulse width, is applied until the control signal reaches a sufficiently stable level, and the voltage is applied to the output terminal r of the switch. Figure 3 (c)
It extracts control signals such as . The above write pulse PW
Even if the laser beam returns to its normal output, it will take some time for the control signal to settle down to its normal level, so if the switch 42 is closed in synchronization with the write pulse, the control signal will be disturbed. This would be extremely undesirable. For this purpose, the delay pulse width x2 is set to be sufficiently larger than x.

"Effect" Thus, according to the method for controlling recording on a medium of the present invention, an abnormal and excessive signal that is mixed into the error signal is applied to the switch of the focus servo system as the output of the laser beam is increased during recording. By applying a delay pulse that is sufficiently larger than the write pulse width to the tracking servo system switch, a control signal with a stable level is obtained.
The actuator equipped with the optical pickup can be controlled stably, resulting in constant laser light output when writing information, uniform information bit diameter, and linearity of information bits. It is something that plays.

[Brief explanation of the drawing]

FIG. 1 shows the electrical characteristics of an optical recording/reproducing apparatus configured to apply a write pulse and a write delay pulse to each switch of a focusing servo system and a tracking servo system when writing information. These are circuit diagrams, in which Figure 2 (A) shows the waveform of the cooling pulse applied to the switch in the focusing servo system in Figure 1, Figure 2 (B) shows the waveform graph of the switch input terminal, and Figure 2 (B) shows the waveform graph of the switch input terminal.
...) is the waveform graph of the output terminal, Figure 3 (a) is the waveform of the write delay pulse applied to the switch in the tracking servo system of Figure 1, and Figure 3 (o) is the waveform at the input terminal of the above switch. Figure (c) is a waveform graph of the output terminal. 1... Photoelectric detector, 21.22.23.24...t
/V converter, 31.32...Error amplifier, 41.42
...Swin-/-151,52...Buffer, 61
．． 62... Phase compensation circuit, 71.72... Output amplifier, 81.82... Actuator, 2... CPU
, 3... Wa/shot multivibrator-Pw...
・Write pulse, xl... Width of Pw, PD... Write delay pulse, X,... Width of PD.

Claims (1)

[Claims] In order to write information to an optical recording/reproducing medium and read recorded information from the medium, a beam emitted from a laser light source is focused on the medium through an optical system, and the beam is scanned along a track. In an information recording method for an optical recording and reproducing medium, when recording information under the action of a focusing servo and a tracking servo, a time constant is set by applying a delay pulse to an excessive component contained in an error signal obtained by a photoelectric detector. 1. A recording control method for an optical recording and reproducing medium, characterized in that a control signal obtained by applying and removing a sufficiently small sample hold is supplied to an actuator on which an optical pickup is mounted.