SU1339641A2 - Automatic focusing device for recording and reproduction optical system - Google Patents

Abstract

Spreading refers to the means of accumulating information. The purpose of the invention is to determine the focusing accuracy. The device .2 I in contains a photodetector I, amplifiers 2 and 5, summing amplifier 3, switch 4. executive element 6, level comparator 7, schemes 8, 14 and 15 coincidence, comparators 9 and 10 levels, main generator AND, elements OR 12 and 13, the counter 16, the start block 17, the analog to analog converter 18 and the HE element 21. The introduction of new elements and the formation of new connections between the elements of the device allows reducing the dynamic focusing error and increasing the stability in the operation of the device, since A digital loop with a high-frequency generator of 20 U-shaped pulses does not extend the bandwidth and amplifier 5 ensures the stability of the device. To eliminate the mutual influence of analog and analog-digital loops, a low-pass filter 19 is integrated, integrating the high-frequency components of the signals arriving at its input. 1 il. ovfi (L with O5 from 05/7 to ISO

Description

The invention relates to the accumulation of information, in particular, to devices for recording and reproducing information from optical disk information carriers, and is an improvement of the device according to the authors. St. No. 1275533.

The aim of the invention is to improve focusing accuracy by reducing dynamic focusing errors.

The drawing shows a block diagram of the device.

The device contains a photodetector unit 1, a differential amplifier 2, a summing amplifier 3, a controlled switch 4, a second differential amplifier 5, an executive element 6, a level comparator 7, the first matching circuit 8, the lower 9 and top 10 comparators, the main generator 11, the first 12 and second 13 elements OR, the second 14 and the third 15 coincidence circuits, the reversible counter 16, the start block 17, the digital-analog converter 18, the low-pass filter 19, the additional generator 20. P-shaped pulses and the 1T element 21. The device 21 slave It is as follows.

Initially, the device performs the Search mode. The start block 17, which is triggered by an operator command from the console, generates a logical 1 signal at the output (the STOP command), upon receipt of which the reversing counter 16 resets the counter content to zero and this state is transmitted to the digital-analog converter 18 The output of which produces a voltage, under the action of which the actuating element 6 (linear motor) mixes the lens to its extreme position. When a start-up block 17 starts up with a logical "O (start command), the main generator 11 of U-shaped pulses is started, the pulses of which through the OR 13 element arrive at the coincidence circuit 15, which is opened by a signal from the start block 17 (logical "ABOUT). These pulses are then fed to the reversible counter 16, which increases its digital content. The increasing digital content is transmitted to the digital-to-analog converter 18, the voltage at its output decreases, and accordingly the lens begins to move toward the surface of the disk.

As the lens moves to the disk surface, the voltage at the output of the differential amplifier 2 begins to change in accordance with the signals from the photodetector unit 1 until the moment at which the voltage at its output lies in the zone near Zero. Then the low-level comparator 9 is triggered, on the signal from which the coincidence circuit 15 stops the pulses from the main generator 11 to the reversing account

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16. If, for any external influences, the reciprocal position of the surroundings of the vector of the optical disk and the optical carrier disk is set, then the comparator 10 of the upper level reads, which means that the lens is too approx. physical to the surface of the disk (away from the focus area) increased statically, in which case the signals to the reversible counter 16 passed through the coincidence circuit 14. The digital content of the pesiCpcHBiioro counter 16 decreases and the voltage at the output of the digital-analog converter 8 increases, as a result of which the positive element 6 returns the objective to the zone close to zero, and the signal at the output of s. the mute amplifier 3 reaches such a magnitude that the level 7 computer is triggered. Under the condition of matching the chip from the outputs to the pairs ;: tori 9, 10 and 7, the first coincidence circuit 8 is triggered, which with its output signal closes the switch 4, as a result of which the signal from the differential amplifier 2 passes through the second differential signal. amplifier 5 on a used battery 6, i.e. locking feedback loop. Simultaneously, the signal from the first circuit 8 coincides with the switching of the generators. On the main generator 11 comes from the element NOT 21 forbidding ciirna. i, and it turns off. a Additional generator 20 H-obz0

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pulses VC, stitch: squared, NOCTV-fuzzy with the first Scheme 8 Sov11ade1 n. As a result, in the tracking mode of the USA, the digital loop operates parallelly. Chipko is aplogic, but the speed is not; 1. 1and the voltage increases compared with the speed in the “Search” mode, since the frequency of the pulses produced by the generator 20 is at least an order of magnitude higher than the frequency of the pulses produced by the generator II . The frequency of operation of the roversivepoghch.) Counter 16 also cooTBCTCTiiCHHO increases as a result of passing on the signals of the generator 20 through the first element of the ILP 12 and the second coincidence circuit 14, as a result of which the device manages to track an optical signal having a sufficient speed the maximum and minimum error, focusing is near the KOMnapaTopoti actuation level. in addition, r | because the levels of maxim. m and min can be sufficiently small. dynamic error can b1) 1x x msh-lpena to minim.ch.

The device is sufficiently stable in operation due to the fact that the digital loop with sufficient high-frequency lopo-oscillator 20 P-volts of pulses does not expand the transmission and the second differential vcn.ni-TC.ib 5 provides stability -, pr, bots in (.- its ycTpoii- stv.a

To eliminate the mutual influence of analog and analog-digital loops at the output of the digital-to-analog converter 18, a low-pass filter 19 is included, integrating the high-frequency components of the signals input to its input.

Claims (1)

Invention Formula Set the automatic focus of the optical recording and playback system by aut. St. No. 1275533, characterized in that, in order to increase the focusing accuracy by reducing the dynamic focusing, an additional generator of U-shaped pulses is introduced into it. the element is NOT and two elements of the SLI, and the main generator is made with additional () L11ITs. The first control input to which the output is not connected via the output of the coincidence circuit, which is also connected to the control input of the additional generator of U-shaped pulses, the first and second outputs of which are connected to the first inputs of the corresponding e, 1 () 1 OR, and the outputs of the main generator are connected to the second inputs of the second and third matching circuits via the corresponding OR elements, the second inputs of which are connected to the corresponding outputs of the additional generator of the U-shaped pulses.