SU1753488A1 - Optical and mechanical device - Google Patents

Abstract

The invention relates to instrumentation, in particular, to digital recording devices on optical media. In order to increase the accuracy and reliability of recording-reproduction, an analog divider, a low-pass filter and a source of corrective pulses are introduced into the device, the output of the Photo-receiver tracking corresponding to the optical information carrier along the moving optical information carrier connected to the input beam. The input of the Denominator of the analog divider is connected via a low-pass filter to the output of a source of corrective pulses, and the output of the analog divider is below It is connected to the input of a differential amplifier. 5 з.п f-ly, 3 silt

Description

 3efciisfe

with

with

The invention relates to devices for recording and / or reproducing information with the mutual relative movement of an optical medium and an optical head and can be used in information technology, in particular in digital audio recording devices, digital video recording, in optical external computer storage devices.

A known method of suppressing tracking errors in a playback device from a disc in which a track tracking error is proposed due to the effect on the magnitude of the error signal of the recording pits is reduced by discrete adjustment of the loop gain. For the three-beam optical design, it is proposed to use the center-beam intensity information for controlling the loop amplifier.

The disadvantage of the analog is the low accuracy and reliability when using it in the information recording mode, due to the fact that in this mode the two side beams operate under significantly different conditions. While the front beam, along the information track on the optical carrier, reads the edge of the reference and unrecorded information track, the back beam reads the edge of the reference and just recorded information track. Therefore, a systematic error appears in the error signal of the autotracking system, which corresponds to the difference in the intensities of the lateral reflected beams, the magnitude of which is also not constant, but depends on the duty cycle of the information to be recorded.

The closest to the proposed technical entity is a recording and reading device from a disk information carrier, which contains optically coupled three-beam radiation source,

Vi ate

00

one

00 00

a splitter with a second optical output optically coupled with at least a three-site photodetector having two outputs Tracking and one output Reproduction, a focusing lens and a movable optical information carrier, as well as a positioning drive, to the input of which through a difference amplifier, an analog divider, an input Denominator which is electrically connected to the Playback of the photodetector output, and the control unit is connected to two outputs. Tracking of the photodetector.

The disadvantage of the prototype is the low accuracy and reliability of recording and reproducing information due to the appearance of a systematic error in the composition of the error signal of the auto tracking system when switching from playback mode to recording mode and vice versa. This is explained by the fact that in playback mode both side beams operate under almost the same conditions, namely both side beams read the boundary between the reference track and the information track, which can be either painted or clear. When switching in the recording The conditions of the two side beams in the auto-tracking system become significantly asymmetrical, namely, the beam that is forward along the rotation of the optical information carrier will always read the boundary between the reference track still unpainted information track, and the beam is yuschiys downstream opicheskogo information carrier rotations at all times will read the boundary between the support track and the other the same information track, just painted middle beam. Therefore, at the output of the differential amplifier, to the input of which two outputs are connected. Tracking of the photodetector, a systematic error appears, the magnitude of which, moreover, is not constant, but depends on the duty cycle of the recorded pits. Therefore, in such a system of auto-tracking, not the middle of the information track will be tracked, but a curvilinear trajectory shifted to the edge. As a result, the pits on the information track will not be recorded in the middle, and, therefore, the accuracy and reliability of recording and reproducing information will be reduced.

The aim of the invention is to improve the accuracy and reliability of recording and reproducing information.

FIG. 1 given a device with a cylindrical storage medium, dry optics and one analog divider; in fig. 2 - the same, inverted optics and one

analog carrier; Fig. 3 shows a device with a disk optical storage medium and two analog dividers.

Optical-mechanical storage

0, the device (FIG. 1) includes optically coupled three-beam radiation source 1 (a laser ruler or a semiconductor laser with a light splitter in the form of, for example, a diffraction grating), a beam splitter 2, a focusing lens 3, and a cylindrical optical carrier 4 information. The second optical output of the splitter 2 is optically conjugated by at least a three-area photodetector (three-, six-, twelve-site-based or other), to the side platforms 5 and 6 of which the side rays reflected from the cylindrical optical information carrier 4 are fed, and per cent5 The central platform 7 drops the central reflected beam. The outputs of photo pads 5-7 are connected respectively to the converters 8-10 current-voltage. The output of the inverter 10 current through the node

0 11 signal reproduction and 12 low-pass filter is connected to the input Denominator of the analog divider 13, to the input of the numerator through which the current-voltage is connected through the converter 9

5 exit Tracking of the extreme platform 6 of the photodetector, corresponding to the back beam along the movement of the carrier 4. The output of the analog divider 13 is connected to one of the inputs of the differential amplifier

0 14, to another input of which, through the converter 9, the current-voltage is connected to the output of tracking the photodetector area 5, which corresponds to the forward movement of the carrier 4 to the beam. Output

5 of the difference amplifier 14 through the control unit 15 is connected to the positioning actuator 16 (made, for example, as a linear electric motor), kinematically connected with a movable optical head 17, including a three-beam radiation source 1, a splitter 2, a focusing lens 3 and a three-site photodetector 5-7.

Optical-mechanical storage

5, the device (FIG. 2) comprises a fixed optical head including a three-beam radiation source 18, a beam splitter 19, with a second optical output which coupled two lateral 20 and 21 and central 22 of the photodetector.

and an immersion lens 23 placed in the side wall of a stationary container 24 filled with immersion liquid 25 with low viscosity and containing a cylindrical optical information carrier 26 Output Output The reproduction of the central area 22 of the photoreceiver is connected to the current-voltage converter 2 Output Tracking the side area 21 of the photoreceiver corresponding to the rear direction of rotation of the cylindrical optical information carrier 26 to the side beam; through the converter 28, the current-voltage is connected to the input An analog divider 29, to the input of the Denominator of which, through a low-pass filter 30, is connected a source output (not shown) of recording pulses, which is also connected to a pulse width conversion unit 31. The output of an analog divider 29 is connected to one of the differential amplifier 32, to another input of which Converter 33; current-voltage; output connected; Tracking of receiver's site 20, corresponding to the forward direction of the cylindrical optical information carrier 26; side beam output. Differential gain output. 32 through an amplifier 34 with a switching gain, to the control input of which a mode signal is supplied, and the control unit 35 is connected to the positioning actuator 36, the load of which is the axial movement actuator stator 37 of the cylindrical optical information carrier 26 whose measles 38 is located on one of the the ends of the carrier 26.

The optomechanical memory device (FIG. 3) contains the same as in FIG. 1, a movable optical head 39 including an optically coupled three-beam radiation source 40, a beam splitter 41, with a second optical output which are coupled to two side 42 and 43 and central 44 areas of the photodetector, and a focusing lens 45. Output Playback of the central area 44 of the photoreceiver connected to current-voltage converter 45. Output Track the side platform 43, corresponding to the back side of the disk optical information carrier 47 along the side beam, through the current-voltage converter 48 is connected to the input of the numerator of the first analog divider 49, to the input of which the Denominator through the pulse-width conversion unit 50 and filter 51 a low-frequency source (not shown) is a recording impulse, which is also connected to the input of the radiation intensity control of the three-beam source 40, the output tracking of the side platform 42, corresponding to moving along the forward movement of the disk optical information carrier 47 to the side beam, through the converter 52 the current-voltage is connected to the input of the numerator of the second analog divider

0 53, to the input the Denominator of which is connected via the second low-pass filter 54 to the input of the pulse width conversion unit 50. The outputs of the first 49 and second 53 analog dividers are connected to two

The 5 inputs of the differential amplifier 55, the output of which is connected via a control unit 56 to a positioning actuator 57, kinematically connected with a movable optical head 39.

0 Optical-mechanical storage device (Fig. 1) works as follows

In the mode of recording information from the output Tracking of the side platform 5 of the photodetector, a signal is read that corresponds to the position of the front side during the rotation of the carrier 4 of the side beam at the interface of the reference and still unrecorded information track. At the same time

0 from the output Tracking of the side platform 6 of the photodetector reads the signal corresponding to the position of the backstream along the rotation of the carrier 4 of the juice beam at the interface of the reference one and just recorded with the center beam of the information track. The magnitude of this second signal depends not only on the position of the beam relative to the interface between the reference and information tracks, but also on the duty cycle

0 recorded pitas Therefore, in the analog divider 13, this multiplicative interference is eliminated by dividing by the reproduction signal read from the central area 7 of the photodetector and formed

5 by a current-voltage converter 10 and a reproduction signal generating unit 11, passed through a low-pass filter 12 with a frequency response close to the current-voltage characteristics of converters 8 and 9 (since the current-voltage converter's bandwidth is much wider). Therefore, at the output of the differential amplifier 14, a system error signal is generated.

5 autotracking, already free from additive interference caused by the recording pitas under the rear beam during the rotation of the carrier 4. This mismatch signal as necessary in the control unit 15 is corrected and processed

positioning drive. In playback mode, both side beams follow the boundary of the reference and recorded information track. Therefore, there is no additive interference at the output of the difference amplifier 14 and, therefore, there is no need for the described dynamic balancing. In this mode, therefore, the input of the Denominator of the analog divider 13 is disconnected from the output of the low-pass filter 12 and connected to some constant voltage the value of which is chosen at such a level that the transmission coefficient from the outputs of Tracking platforms 5 and b to both inputs of the difference amplifier 14 will be the same.

Optical-mechanical storage device (Fig. 2) works as follows.

In the recording mode from an external source of recording pulses, video pulses are supplied to the input of the recording pulse 31 to the input of the recording pulse 31 of the recording pulses, the duration of which is approximately equal to the duration of the video playback pulses. In the recording pulse width conversion unit 31, the input video pulses are shortened, since the feeding process usually requires a shorter duration than the reading duration of the formed pit at the same rotational speed of the cylindrical optical information carrier 26. These shortened pulses modulate the radiation intensity of a three-beam radiation source 18, the central beam of which is of relatively higher intensity recordings on the information tracks of the carrier 4. At the same time, the side beams of relatively low intensity provide tracking of the information track. As in the previous embodiment of the claimed device, the multiplicative interference in the signal read by the lateral pad 21 corresponding to the backward rotation of the carrier 4 to the beam is eliminated by dividing this multiplicative interference, which is generated by passing through the filter 30 through the low frequency signal from the output source of recording pulses, the duration of which is chosen approximately equal to the duration of the reproduction pulses (and which they simulate). Such a variant of the formation of correction pulses is more preferable than in

in the previous case, since the playback pulse parameters in the recording mode depend on a large number of factors and are unstable. The error signal of the autotracking system, taken from the output of the difference amplifier 32, is transmitted to the control unit 35 through the amplifier 34 with a switched gain, the value of which is switched by the mode signal. This ensures that the loop gain in the recording and playback modes is equalized, which contributes to an additional increase in accuracy and reliability of tracking the road. The signal from the output of the control unit 35 is fed to the positioning actuator 36, the load of which is served by the stator 37 of the motor for axial movement of a cylindrical optical carrier 26

0 information regarding a fixed immersion lens 23. In the playback mode, a constant voltage is applied to the input of the low-pass filter 51, since the input of the conversion unit

5 pulse duration no trigger pulses that provide equal transmission coefficients of the signal amplification channels Tracking from the outputs of the side platforms 20 and 21 of the photodetector

0 to the inputs of the differential amplifier 32.

Optical-mechanical storage device (Fig. 3) works as follows.

From an external source to a three-beam

5, the radiation source 40 is pulsed with a shortened duration required for optimum pit formation, which modulates the radiation intensity of all three beams. However, recording information

0 in the information tracks of the disk optical information carrier 47 is produced only by the central beam, the intensity of which is relatively higher. The lateral rays are used for the trail5 behind the information track. In this case, the multiplier interference in the signal read from the side platform 43 of the photodetector corresponding to the backward direction of the carrier 47 to the beam eliminates the first described analogue divider 49. The duration

correction pulses applied to the input of the first low-pass filter 51 increase and are set to approximately

5 equal to the duration of the reproduction pulses in the pulse width converting unit 50, which is triggered by the recording pulses. But in the latest implementation of the claimed device, the multiplicative interference is also eliminated in the signal.

readable from the side platform 42 of the photodetector corresponding to the forward beam along the rotation of the optical disk 47 of information. But since this multiplicative interference due to the greater duty cycle of the recording pulses has a smaller value, the input of the Denominator of the second analog divider 53 through the second low-pass filter 54 (whose frequency response should be similar to the frequency response of the first low-pass filter 51) is directly written to the write pulses. Thus, at the output of the difference amplifier 55, the effect on the error signal not only of the write pits, but also on the intensity modulation of the write pulses of the forward beam carrier 47 of the side beam, is eliminated. The processing of the error signal is the same as in the device shown in FIG. 1. In the playback mode, the inputs of the Denominator of the first 49 and second 53 analog dividers are supplied with constant voltages equalizing their transfer coefficients, which provides a dynamic balancing process,

Claims (6)

Claim 1. Optomechanical memory device containing optically coupled three-beam radiation source, a beam splitter, with a second optical output of which is optically coupled with at least a three-site photodetector having two outputs Tracking and one output Playback, focusing lens and a movable optical storage medium as well as a positioning actuator, to the input of which a difference amplifier is connected through the control unit, with two inputs of which two outputs C are electrically connected Photo detector receiver, characterized in that, in order to improve the accuracy and reliability of recording and reproducing information, a low-pass filter, a source of corrective pulses and an analog divider, are inputted to the numerator of which is connected to the Photo tracking receiver corresponding to the latter in the direction of movement of the information track the moving optical information carrier to the optical beam, and the input of the Denominator through the low-pass filter is connected to the output of the source of correction pulses, the output is analog beef divider connected to the input of a differential amplifier 2. The device according to claim 1, wherein the source of the correction pulses is made in the form of a reproduction signal generating unit connected to the output of the Reproduction of the photodetector. 3. The device according to claim 1, characterized in that a source of recording pulses is used as a source of corrective pulses, connected to the input control of the radiation intensity of the three-beam radiation source. 4. The device according to claim 1, characterized in that the source of corrective pulses is made in the form of included pulse recording source and pulse width conversion node, where the output of the recording pulse source is connected to a low-pass filter, and the output of the duration conversion node pulses - to the intensity control of the radiation intensity of the three-beam radiation source. 5. The device according to claim 1, characterized in that the source of the correction pulses is made in the form of a series-connected source of recording pulses and a pulse width conversion unit, with the output of the source of recording pulses connected to the input of the control unit the intensity of the radiation of the three-beam radiation source, and the output of the pulse width conversion unit to the low-pass filter. 6. The device according to PP. 1-5, that is, so that the second low-pass filter and the second analog divider are introduced into it, to the input of which is connected the output of the tracking photoreceiver corresponding to the first in the direction of movement of the information track on the moving optical the information carrier to the optical beam; to the input; the Denominator — through the second low-pass filter — the input of the radiation intensity control of the three-beam radiation source; the output of the second analog divider is connected to the input of the difference amplifier. I IS Fig.Z