SU1282201A1 - Device for tracking information track of optical record medium - Google Patents

Abstract

The invention relates to the accumulation of information, specifically devices for reproducing information from disc-shaped recording media on which it is located in an optically reproducible information structure. The purpose of the invention is to increase the exact & (L hce bo iNd yu

Description

(21) 3871208 / 24-10

(22) 03/21/85

(46) 1/7/87. Bul № 1

(72) A.P. Dovgan, V.A. Smirnov

and V.I. Butt

(53) 681.840.838 (088.8)

(56) U.S. Patent No. 3,944,727,

cl. G 11 B 21/10, 1976.

USSR Author's Certificate No. 837338, cl. G 11 B 7/00, 1980.

(54) DEVICE FOR TRACKING FROM THE INFORMATION TRACK OF THE OPTICAL RECORDING MEDIA

(57) The invention relates to the accumulation of information, specifically devices for reproducing information from disc-shaped recording media on which it is placed in an optically reproducible information structure. The purpose of the invention is to increase the exact

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tracking the information track by increasing the sensitivity of the swivel mirror. The device for tracking the information track of the optical recording medium comprises a rotating mirror mounted on a metal beam 13 with a control piezoceramic plate 14 and a piezoceramic feedback plate 16 connected to a pulse shaper 11. On the other side of the beam 13, there is a different control piezoceramic control plate 15 with a polarization opposite to that of the control piezoceramic plate 14 and the piezoceramic feedback plate 16. This leads to their summation.

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The invention relates to the field of storage of information, in particular, to devices for reproducing information from disc-shaped recording media on which it is placed in an optically reproducible information structure.

The purpose of the invention is to improve the accuracy of tracking the information track.

Figure 1 shows the block diagram of the device; in fig. 2 — the scanning unit of the first mirror j in FIG. 3 — connecting the piezoceramic plates with the pulse shaper.

The device (Fig. 1) contains a radiation source 1 (laser), node 2, scanning the first mirror, matching lens 3, second mirror 4 with a 5-turn actuator, lens 6, optical recording medium 7, photo receiving unit 8, synchronous detector 9, amplifier 10 error signal and driver 11 pulses.

The scanning unit 2 of the first mirror (Fig. 2) comprises a housing 12 with a flat beam 13 fixed on it, on which the main 14 and an additional 15 piezoceramic drive plates, a piezoceramic feedback plate 16 and a mirror 17 are located. The imaging unit 11 is bending beam 13 and an increase in scanning amplitude. The outer surfaces of the two control plates 14, 15 are connected in parallel and electrically with the driver 11 pulses. Shaper 11 is made of amplifier limiter 19, the rectangular signals of which are converted by a controlled oscillator 18 into a triangular signal. This automatically shifts the phase of the control signal relative to the U-shaped signal of the plate 16 by. Due to this, the oscillations of the beam 13 with the mirror 17 on its own mechanical resonance are maintained regardless of external influences. 3 cl.

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The squares (FIG. 3) consist of a controlled oscillator 18 and an amplifier-limiter 19.

The device works as follows.

The scanning unit 2 of the first mirror (Fig. 1) is scanned, the radiation of the radiation source 1 is irradiated with a frequency of a pulse shaper 11 and with a constant amplitude.

The radiation passes the matching lens 3 and is guided by the second mirror 4 to the lens 6, which forms a reproduction spot on the optical recording medium 7.

As a result of the reproduction scan, the spot periodically shifts across the information track of the optical recording medium 7 with a fixed amplitude, for example, 0.1 of its diameter. The radiation arriving at the photodetector unit is modulated in intensity with the frequency of the impulse:: pulse generator 11 and with a given modulation depth, for example 10%, which causes a similar modulation of the signal of the photodetector unit 8, which is separated, for example, by a bandpass filter is shown) and is fed to the first input of the synchronous detector 9. The second input of the synchronous detector is fed a reference signal from the driver 11 pulses, in

the result of which the synchronous detector generates a signal, the amplitude and polarity of which indicate the magnitude and direction of the spot reproduction relative to the center of the information track j of the optical recording medium. The received signal is amplified by the error signal amplifier 10 and fed to the actuator 5 of the rotation of the second mirror 4, which moves the reproduced radiation in such a way that the offset of the information track relative to the spot reduces

As a result, the signal- / 5 P-mode signal is exactly -90 ° C, with continuous tracking of the information track.

The first and second piezoceramic plates 14 and 15 (FIG. 2) are mounted on a flat beam 13 of the housing 12 20 of the first mirror scanning unit 2, and the width of the additional plate 15 may be less (for example, 25%) than the width of the main plate 14. Piezoceramic The feedback plate 25 of the connection 16 is located on the same side of the flat beam 13 as the additional Piezoceramic plate 15, while the width of the feedback plate is smaller (for example, -30 by 75%) than the width of the main piezoceramic plate 14.

The main and additional plates differ in the opposite direction of polarization, thanks to which, when the control voltage is applied to them, one is shortened and the other lengthens, hence the force applied to the beam, at the end of which the mirror 17 is reinforced, is summed, and the position the mirror at the end allows an increase in the scanning amplitude.

as a result, beam oscillations are maintained at their own mechanical resonance regardless of external influences.

Claims (1)

Invention Formula A device for tracking the information track of an optical recording medium, comprising a radiation source optically coupled to a first scanning-scanned mirror, a matching lens, a second turning-operated mirror, an objective lens and a photoreceiver node, the output of which is connected to the first input of a synchronous detector whose second input is connected to the first input of the pulse former, and the output through the error signal amplifier to the input of the rotation drive of the second mirror; the second output of the pulse former is connected to the input drive scan of the first mirror, which is located on a flat beam, one end of which is fixed in the housing, on the first side plane of the beam is placed a scan drive in the form of a piezoceramic plate of direct polarization, and on the second side plane - a piezoceramic back coupling plate The electrical output of which is connected to the input of the pulse former, characterized in that, in order to increase the accuracy of tracking the information track, an additional Piezoceramic drive plate sk is introduced into it. located on the second side plane of the beam, connected to the second output of the pulse former and having polarization opposite to the polarization The reverse-coupling piezoceramic plate 16 is fixed on the beam 13 by a surface of the same polarity as the main piezo-ceramic plate 14, as a result of which the signal removed from the feedback plate at the mechanical resonance of the back shaft is shifted relative to the control signal by -90 ° (in the case of a different polarity of the feedback plate, it is shifted by +90). Therefore, to maintain beam self-oscillations at resonance, a phase shift of an additional -90 is necessary. Amplifier-limiter 19 pulse former - 22014 The tips are designed to be powerless, so that the signal of the feedback plate is amplified and limited to a U-signal without phase shifts. Consequently, the signal of the attenuator 19, suitable for synchronous switching of the synchronous detector 95, is fed to its control input without any changes. The same signal goes to the input. Sh controlled oscillator 18, which converts it into a triangular signal, shifting the phase of the triangular controlling signal with respect to / 5 P-mode signal exactly at -90 °, 0 5 0 50 0 five as a result, beam oscillations are maintained at their own mechanical resonance regardless of external influences. Invention Formula A device for tracking the information track of an optical recording medium, comprising a radiation source optically coupled to a first scanning-scanned mirror, a matching lens, a second turning-operated mirror, an objective lens and a photoreceiver node, the output of which is connected to the first input of a synchronous detector whose second input is connected to the first input of the pulse former, and the output through the error signal amplifier to the input of the rotation drive of the second mirror; the second output of the pulse former is connected to the input drive scan of the first mirror, which is located on a flat beam, one end of which is fixed in the housing, on the first side plane of the beam is placed a scan drive in the form of a piezoceramic plate of direct polarization, and on the second side plane - a piezoceramic back coupling plate The electrical output of which is connected to the input of the pulse former, characterized in that, in order to increase the accuracy of tracking the information track, an additional Piezoceramic drive plate sk is introduced into it. located on the second side plane of the beam, connected to the second output of the pulse former and having polarization opposite to the polarization the main piezoceramic plate, the piezoceramic feedback plate has a polarization, the opposite polarization of an additional piezoceramic plate, the mirror is located at the end of the beam, and the pulse shaper / J made of a series-connected limiting amplifier and controlled oscillator, with the input of the pulse generator being the input of the limiting amplifier, the first output of the controlled oscillator, and the second output of the limiting amplifier. .15 G2