RU2140672C1 - Optical reader (design versions) - Google Patents

Abstract

FIELD: computer engineering. SUBSTANCE: reader has light source, beam splitter, lens for focusing light beam on disk, numerical aperture control, and photodetector. Numerical aperture control is made for controlling effective value of lens numerical aperture to focus beam on disks of different thickness. Second design version has, in addition, newly introduced repetition rate control unit, focus control unit, reproducing signal processing device, disk identifier, numerical aperture control drive, spindle motor, motor control unit, and microcomputer. Third design version incorporating mechanical system with motor and optical system with light source, photodetector, lens for focusing light on disk, and numerical aperture control has its optical system provided with prism and its light source and photodetector made in the form of assembly, and numerical aperture control made for controlling numerical aperture of lens to focus beam on disks of different thickness; its mechanical system motor is movable member built integral with optical system. EFFECT: provision for reading data off disks of different thickness. 51 cl, 39 dwg, 2 tbl

Description

 The invention relates to an optical reader capable of reading data from disks of various types and, in particular, to an improved reader capable of reading data from disks of various types, capable of reading data from a specific disk among disks of various thicknesses and recording densities, using only one reader device.

 Typically, a digital video disc is equipped with a semiconductor laser operating in the red region of the visible spectrum, and a lens having an enlarged numerical aperture. The aforementioned video disc has a capacity, determined by the amount of recorded data, 6 or 8 times the capacity of a CD in which compressed image and sound data can be stored. Thus, a disc having a diameter of 120 mm can store data corresponding to a video movie.

 A digital video disc is read by a semiconductor laser operating in the red region of the visible spectrum, having a wavelength of 635 or 650 nm.

 Typically, if the wavelength of the light source becomes shorter, the diameter of the laser spot decreases in proportion to the wavelength, so that the pitch of the recording tracks and the minimum length of the recording mark can be reduced. That is, since the surface of the recording mark is quadratic with the wavelength of the recording mark, the total recording area can be reduced.

 The diameter of the laser spot is proportional to the wavelength of the light source. Therefore, if you increase the numerical aperture without changing the wavelength, you can increase the recording density. Therefore, the numerical aperture in the optical system for a compact disc is about 0.45, but equal to about 0.6 for a digital video disc.

 There are 3 methods below for reading data from a disc for a regular digital video disc.

 In the first method, a slight increase in the numerical aperture is simply carried out. The second method uses a device for compensating for the angle of inclination of the disk, called the automatic tilt control system, in the optical reading system instead of increasing the numerical aperture to a value exceeding 0.52. In the third method, the numerical aperture is increased to 0.6 and the path length of the laser beam through the disk plate is reduced.

 Let us now explain the design of a conventional optical reader.

 As shown in FIG. 1, a conventional optical reader includes a diffraction grating 2 for dividing the beam from the light source into the main beam and two sub-beams for the automatic follow-up of the reading beam. In addition, the beams from the diffraction grating 2 pass to the lens 5, which serves to collect light in the spot on the optical disk 6, through the collimator lens 4, which serves to obtain a parallel beam of light, and through the beam splitter 3. In addition, the photodetector 8 detects a signal from read by the beam data transmitted from the lens of the photodetector 7, which serves to collect the beam.

 Let us now explain the operation of a conventional optical reader according to the accompanying drawings.

 The beam from the light source 1 is converted into a parallel light beam by the collimator lens after passing through the beam splitter 3. The beam is focused by the lens 5 and is reflected or diffracted by the information recording surface of the information carrier. Thus, the reflected beam returns along the same optical path and is converted into an electrical signal by a photodetector. That is, the beam passes to the photodetector 6 along a different path formed by the beam splitter 3, through the lens of the photodetector 7.

 Meanwhile, the diffraction grating 2 and lens 7 are widely used in the automatic control system by following the reading beam, using the 3-beam method and the automatic focus control system, using the astigmatism compensation method.

 An optical disc with a high recording density has a capacity 4 times the capacity of a conventional compact disc and the data stored on it can be reproduced using a lens having a numerical aperture of about 0.6. In this case, as the thickness of the disk increases, aberration increases due to the inclination of the disk. To solve this problem, the standard for a digital video disc requires a disc thickness of 0.6 mm.

 This time, the optical system shown in FIG. 1 includes an optical disc with a high recording density having a thickness of 0.6 mm and a compact disc having a thickness of 1.2 mm. However, the aforementioned optical system has the following disadvantages.

 For example, the distribution of the beam intensity at the focal point on the surface of a disk having a thickness of 0.6 mm using a lens having a numerical aperture of 0.6 is shown in FIG. 2 solid line. When the beam is focused by a lens on a disk having a thickness of 1.2 mm, the beam intensity distribution is as shown in FIG. 2 by a dashed line due to spherical aberration.

 That is, the intensity of the beam of the main diffraction maximum decreases significantly and the intensity of the beam of the lateral diffraction peaks increases, so that the crosstalk of the signal recorded on the adjacent track of the disk increases.

 In addition, the optical reader cannot reproduce data stored in a disc having a thickness of 1.2 mm, since the sensitivity with respect to the level of inclination of the disc is too high, as shown in FIG. 1 if data is read using a lens having a numerical aperture of 0.6.

 The closest analogue of the present invention are objects of the same purpose, known from the application of Great Britain N 2095886 (M.cl. G 11 B 11/10, 7/00, published. 1982), which describes an optical reader containing a light source, which through installed sequentially, a splitter and a lens with a controlled numerical aperture (made in the form of an iris diaphragm) irradiates the surface of the optical disk so that the light reflected from it enters the photodetector. The iris diaphragm, which sets the numerical aperture, is controlled from the corresponding control unit.

 Thus, the technical task of the present invention is to develop an optical reader capable of reading data from various types of disks, devoid of the disadvantages of a conventional optical reader unable to read data from various types of disks, and to develop an improved optical reader capable of reading data from various disks types having different thicknesses and densities using only one reader.

 To achieve the above objective, an optical reader has been developed that can read data from various types of disks, containing a light source, a beam splitter for passing through it or splitting the beam from a light source, a lens for collecting the beam onto a disk, a numerical aperture control tool and a photodetector for receiving the beam reflected by the disk and passed by the beam splitter, the numerical aperture control means being configured to control the effective value of the numerical aperture lens for the process of focusing the beam on disks of different thicknesses.

An optical reader capable of reading data from various types of disks in an optical system, comprising a light source designed and intended to emit a light beam, a collimating lens designed and designed to collimate a light beam to give it parallelism, a diffraction grating located between the light source and a collimating lens, a lens for collecting a light beam onto an optical disk, a numerical aperture control means, a photodetector assembly, designed and designed to receive the light reflected by the optical disk in accordance with the incident light beam, and to generate a first signal in response to the light reflected by the optical disk, a beam splitter designed and designed to transmit the beam from the light source to the lens and to reflect light, reflected by the optical disk to the photodetector, the numerical aperture control means configured to control the numerical aperture of the lens by controlling the size of the light beam reaching the object willow, while the follower control unit, the focus control unit,
means for processing the reproducing signal for transmitting the second signal to the tracking control unit and the focus control unit, respectively, in response to the first signal from the photodetector assembly,
disc identification means for identifying the optical disc by the thickness of the optical disc and for generating a corresponding third signal based on the second signal from the reproduction signal processing means,
a drive device for controlling the numerical aperture, which is used to actuate the controls for numerical aperture in response to the identification of the optical disk by its thickness by means of identification disk
spindle motor
an engine control unit for controlling the spindle motor in accordance with the identification of the optical disk, and
a microcomputer designed and designed to selectively control at least one of the numerical aperture control means, the focus control unit, the follow control unit and the engine control unit in accordance with a third signal from the disk identification means, and
an optical reader capable of reading data from various types of disks, comprising a mechanical system and an optical system including a light source, a photodetector, a lens for collecting light on a disk, and a numerical aperture control means, wherein the mechanical system includes an engine, wherein a prism has been introduced into the optical system to form the light path from the light source to the photodetector, which are made in the form of a single assembly, the means for controlling the numerical aperture is made with the possible the ability to control the numerical aperture of the lens to carry out the process of focusing the beam on disks of different thicknesses, and the engine of the mechanical system is movable and integral with the optical system.

 In FIG. 1 is a schematic view illustrating a conventional optical reader.

 In FIG. 2 shows a graph of the beam intensity distribution on disks having different thicknesses in a conventional optical reader.

 In FIG. 3 shows a block diagram of a first embodiment of the proposed optical device.

 In FIG. 4 shows a schematic view of the drive of the proposed optical reader.

 In FIG. 5 is a perspective view of a liquid crystal optical modulator, which is one element of a numerical aperture control unit according to the present invention.

 In FIG. 6A is a view illustrating light transmission when voltage is applied to the liquid crystal optical modulator in normal white mode according to the present invention.

 In FIG. 6B is a view illustrating light transmission when voltage is applied to the liquid crystal optical modulator in normal black mode.

 In FIG. 6C is a view illustrating an example of a circuit by which a voltage is applied to the optical modulator of FIG. 6C according to the present invention.

 In FIG. 6D and 6E are views illustrating a change in the direction of polarization within a twisted nematic liquid crystal according to the present invention.

 In FIG. 6F and 6G are views illustrating the passage of light when voltage is applied to an optical liquid crystal modulator having a liquid crystal layer dispersed in a polymer according to the present invention.

 In FIG. 7A and 7B are views illustrating electrode patterns in an optical liquid crystal modulator according to the present invention.

 In FIG. 8A is a graph illustrating jitter versus contrast ratio according to the present invention.

 In FIG. 8B shows a view of a glass plate on which a transparent electrode is formed according to the present invention.

 In FIG. 9A is a graph illustrating the dependence of crosstalk on the numerical aperture of a lens according to the present invention.

 In FIG. 9B is a graph illustrating the dependence of the reproducing signal on the numerical aperture of the lens according to the present invention.

 In FIG. 9C is a graph illustrating the dependence of crosstalk on contrast ratio according to the present invention.

 In FIG. 9D is a graph illustrating the dependence of the gain of the reproducing signal on the contrast ratio.

 In FIG. 10 shows a wiring diagram of a circuit part of a first embodiment of an optical reader.

 In FIG. 11A is a schematic view illustrating the construction of a solar cell according to the present invention.

 In FIG. 11B is a diagram of a reproducing signal processing unit according to the present invention.

 In FIG. 12 is a block diagram of a disc identification unit according to the present invention.

 In FIG. 13 is a plan view illustrating a first embodiment of an optical reader of the invention.

 In FIG. 14 is a perspective view of the base of a reader of the present invention.

 In FIG. 15 is a perspective view illustrating a holder cooperating with the base of the reader of FIG. 14 according to the invention.

 In FIG. 16 is a perspective view of an iris-type optical modulator.

 In FIG. 17A and 17B are views illustrating an iris-type optical modulator in positions providing a small numerical aperture for a CD and a large numerical aperture for a digital video disc.

 In FIG. 18 is a diagram of a numerical aperture control device when an optical modulator of the iris type is used in the optical system instead of the liquid crystal optical modulator of the first embodiment of the present invention.

 In FIG. 19 is a block diagram of a numerical aperture control device of FIG. 18, according to the present invention.

 In FIG. 20 shows a diagram of a second embodiment of the present invention.

 In FIG. 21 is a perspective view of a base of a reader used in a second embodiment of the present invention.

 In FIG. 22 is a perspective view illustrating a disassembled iris control for use in the base of the reader of FIG. 21, according to the present invention.

 In FIG. 23 shows a perspective view of a holder interacting with the base of a reader.

 In FIG. 24 is a perspective view illustrating a numerical aperture control unit of a third embodiment of the proposed optical reader using a laser communication element.

 In FIG. 25 is a view illustrating an assembly consisting of a laser diode and a photodiode, an optical reader of the present invention using a laser communication element.

 In FIG. 26 is a connection diagram of a focus error and signal detection unit of the proposed optical reader using a laser communication element.

 First of all, we describe the embodiments of the proposed optical reading device and an optical system free from aberrations.

The size of the spot formed by the optical system, free from aberration, can be calculated by the following formula, taking into account light diffraction:
Spot size = Kλ / 2 (N • A) (1)
where K denotes a constant determined in accordance with the characteristic of the distribution of light intensity in a beam with an ordinary light wave, a Gaussian beam or a truncated beam, and λ denotes the wavelength of the light source used and NA denotes a given numerical aperture.

 According to formula (1), as the numerical aperture increases, the spot size decreases. For example, in the case of a disc with a high recording density having a thickness of 0.6 mm, since the distance between the tracks and the diameter of the pits are small, it is necessary to have a specific spot having a relatively small size, and a lens having a large numerical aperture is required. However, in the case of a disk having a thickness of 1.2 mm, since the distance between the tracks and the size of the pits is larger than that of a disk having a thickness of 0.6 mm, with a slight increase in the spot size, you can read data and use a lens having a small effective numerical aperture when reading a disc with a high recording density.

 The relationship between the numerical aperture and the size of the beam of light incident on the lens can be expressed by the following equation.

D = 2f (NA), (2)
where D is the diameter of the incident beam and f is the focal length of the lens.

 That is, when controlling the size of the incident beam of the lens having the same focal length, the effective numerical aperture of the lens can change.

 When reading data stored on a disk having a thickness of 1.2 mm in an optical system including a lens having a numerical aperture of 0.6 and a disk with a high recording density having a thickness of 0.6 mm, the following problems arise.

 First, if focus correction is not performed, proper focus cannot be achieved due to the loss of clarity phenomenon.

 Secondly, the signal-to-noise ratio decreases due to an increase in crosstalk due to interference of signals from neighboring tracks due to a decrease in the intensity of the central diffraction maximum due to spherical aberration, which occurs as a result of a change in the thickness of the disk, and an increase in the intensity of the first lateral diffraction maximum.

 Thirdly, the optical system becomes unstable due to coma and astigmatism, which occur due to the inclination of the disk.

 Thus, it becomes impossible to read data stored on the disc due to deterioration of optical characteristics, as explained above.

где n обозначает показатель преломления, Δd обозначает степень изменения толщины, N.A обозначает числовую апертуру.Meanwhile, spherical aberration due to changes in disk thickness can be calculated using the following equation

where n is the refractive index, Δd is the degree of change in thickness, NA is the numerical aperture.

In addition, the amount of aberration due to defocus can be determined using the following equation
ΔWFE _DF-RMS = (1/4 3) (N • A) ² ΔZ, (4)
where ΔZ denotes the degree of defocus.

 When calculating the magnitude of the aberration taking place and the intensity of the central diffraction maximum when reading data stored on a disk having a thickness of 1.2 mm using a lens with a numerical aperture of 0.6 and reading data stored on it by changing the effective numerical aperture, making its equal to 0.3, using the control unit of the numerical aperture, by moving the focus to the data recording surface of the disk having a thickness of 1.2 mm, and by eliminating any interference with respect to defocus, can be obtained tab. 1.

 The mean square aberration of the wavefront of the entire optical system, in which the approximately absence of aberration could be expressed as a function of the intensity of the central diffraction maximum, would have to be less than 0.07 λ if the intensity of the central diffraction maximum was more than 80% in accordance with the criterion Mareshalya.

 As shown in the above table, by changing the effective numerical aperture of the lens used, by moving the focus to the data surface of the disc having a thickness of 1.2 mm, in order to eliminate any interference with respect to defocusing, it is possible to read data.

 In addition, when the effective numerical aperture is changed using the numerical aperture control unit, since the magnitude of the aberration occurring with respect to the tilt of the disc can be reduced as follows, a more stable optical system can be obtained.

Когда показатель преломления "n" в соответствии с уравнением (5) равен 1,55, диск имеет толщину 1,2 мм, наклон диска составляет 0,6^o и длина волны источника света составляет 635 нм, величина имеющей место аберрации приобретает значения, приведенные в табл. 2.

When the refractive index "n" in accordance with equation (5) is 1.55, the disk has a thickness of 1.2 mm, the inclination of the disk is 0.6 ^o and the wavelength of the light source is 635 nm, the magnitude of the aberration takes the values given in table 2.

 However, as follows from equations (1), if the effective numerical aperture decreases, the size of the launch spot increases with respect to diffraction, and when the size of the spot exceeds a predetermined value, which is determined by the type of disk, crosstalk occurs due to an increase in the size of the spot, and not a change in the intensity distribution due to aberration, so that the signal-to-noise ratio of the read signal becomes unsatisfactory.

 Therefore, the value of the effective numerical aperture exists in a certain range of values and the maximum value of the effective numerical aperture is limited by the change in the state of the intensity distribution due to aberration, while the minimum value is limited by the increase in the size of the spot.

 To meet these conditions, when using a lens having a numerical aperture of 0.6 with respect to a disk having a thickness of 0.6 mm, an effective numerical aperture can be selected within the following limits when reading data stored on a CD.

0.27 <effective numerical aperture <0.5
Regarding the range of the aforementioned effective numerical aperture, refer to FIG. 9A and 9B below. That is, in FIG. 9A shows the dependence of crosstalk on the numerical aperture of the lens, and FIG. 9B shows the dependence of the reproducing signal on the numerical aperture of the lens.

 According to the above principles, in an optical reader, by a method of reading data recorded on a disk with a high recording density having an enlarged numerical aperture of the lens and a reduced thickness of the disk for reading data stored on a disk of a larger thickness having a low recording density, the inventor of the present invention realized that the objectives of the present invention can be achieved by changing the effective numerical aperture of the object to satisfy inequality conditions (6) by providing a block board numerical aperture.

 We now describe the design of the first embodiment of the proposed optical reader, capable of reading data from disks of various types.

 In FIG. 3 shows an optical system of a first embodiment of the present invention.

 As shown in FIG. 3, the optical reader includes an optical system “A” and a circuit device “B”, indicated by dashed lines, respectively.

 The beam from the light source enters the lens 25 through the diffraction grating 24 and the beam splitter 23. In addition, between the lens 25 and the beam splitter 23 there is a control unit for the numerical aperture 30, which serves to change the effective numerical aperture of the object 25 when the beam passes to the object. Moreover, although the numerical aperture control unit is connected to the drive unit 26, the goals of the control unit 30 can be achieved using other elements (not shown) located between the lens and the light source, or made in one piece between the lens 25 and the light source 21 .

 The light from the control unit of the numerical aperture 30 enters the disk 10 through the lens 25. The beam reflected by the disk enters the lens 25 and the beam splitter 23 along the same path. In addition, the path of the optical signal modulated by the signal of the disk information recording surface is changed by the beam splitter 23, and the signal is transmitted to the photodetector 28 through the lens of the photodetector 27. The photodetector performs the function of converting the optical signal into an electrical signal.

 The electrical signal generated at the output of the photodetector 28 is supplied to the microcomputer 800 through the processing unit of the reproducing signal 500 and the disc identification unit 550. In this case, the signals from the follower and the focus beam coming to the follower control unit 600 and the focus control unit 650 are output from the block 500 in accordance with the signal received from the photodetector 28. In addition, the output of block 500 is fed directly to the disc identification block 550 or to the digital signal processing unit 750 during processing sweeps of the reproducing signal in block 500.

 The microcomputer 800 outputs an output signal corresponding to the thickness of the disk 10 to the drive unit of the numerical aperture control unit 400 to drive the numerical aperture control unit 30, which controls the numerical aperture corresponding to various types of disks, and to the focus control unit 650 for adjusting the initial focus the lens 25 and for controlling focusing, respectively, in accordance with the signal from the output of the disc identification unit 550.

 In addition, the microcomputer 800 is connected to an engine control unit 700 for controlling a spindle motor (not shown) in accordance with the type of disk 10. The engine control unit 700 is connected to a digital signal processing unit 750.

 The lens 25 is able to move in accordance with the movement of the drive unit 26 having a drive coil.

 We now describe the design of the optical system "A", including an optical modulator on a liquid crystal, which performs the function of a control unit for numerical aperture 30.

 In FIG. 4 shows a drive having an optical liquid crystal modulator as one of the numerical aperture control units.

 As shown in FIG. 4, the actuator 40 includes a next coil 26a and a focusing coil 26b wound on an outer peripheral surface of the engine 25a having a lens 25, a collar 45 engaged with the motor 25a, a follower coil 26a and a focusing coil 26b, and a base of the actuator 29 for mounting the collar 45. In addition, at both ends of the engine 25a there is a protrusion 34 for coming into contact with the drive 35 of the rear plate 32b through the slit hole of the support frame 32. A hole 29a for the passage of light is made in the central part of the base of the drive 29.

 In the lower part of the mover 25 is located an optical modulator on a liquid crystal 44 ', having many plates and located at some distance from the lens 25.

 As shown in FIG. 5, the optical modulator 44 ' has a size and a shape of a light beam on two transparent plates 66 and 70 so as to be controlled by the transparent electrodes 67a and 67b.

где δn - разность в показателях преломления между показателем преломления N_o обыкновенных лучей и показателем преломления N_e необыкновенных лучей в отношении длины волны λ .Between the transparent electrodes 67a and 67b on the transparent plates 66 and 70, a predetermined clearance “d” is defined as defined by the following equation. The condition for the minimum perceived brightness difference of the mth order can be expressed by the following equation

where δn is the difference in refractive index between the refractive index N _{o of} ordinary rays and the refractive index N _{e of} extraordinary rays with respect to wavelength λ.

 An optical modulator on a liquid crystal is formed by placing a twisted nematic liquid crystal 68 in the gap “d” and by contacting with polarizers 71 and 74 located on the output side of the transparent plate 70 in order to have the same direction of polarization of the output light.

As shown in FIG. 5, the light beam 72 incident from the side of the input transparent plate 66 passes through the transparent electrodes 67a and 67b and the liquid crystal layer 69. In this case, the direction of polarization of the incident light is rotated 90 ^° by setting a 90 ^° rotation in the twisted nematic liquid crystal layer in the state when no supply voltage is applied to it, and by controlling the size of the gap "d".

 That is, as shown in FIG. 5, the direction of rotation is indicated by arrow 73.

 In addition, when a liquid crystal dispersed in the polymer is introduced into the liquid crystal layer, there is no change in the direction of polarization of the incident light passing through layer 68, which is different from the liquid crystal layer based on the inherent characteristic of the liquid crystal dispersed in the polymer. When using the aforementioned characteristics of a liquid crystal dispersed in a polymer, it does not need the aforementioned structure, although it is necessary to have an additional polarizing plate in order to block incident light as the direction of polarization in the twisted nematic liquid crystal changes. Therefore, as shown in FIG. 6A-6G, a pattern of transparent electrodes 67a, 67b and 67c is formed and a liquid crystal layer is formed by a liquid crystal dispersed in the polymer instead of a twisted nematic liquid crystal. When applying and removing voltage from the transparent electrodes, the incident light entering the region of the liquid crystal layer, to which voltage is not applied, is scattered and does not pass to the output side. In addition, incident light entering the region in which the voltage is applied passes to the output side.

 In FIG. 6A shows a state where a voltage is applied to an electrode of an optical liquid crystal modulator in a normal white mode, and FIG. 6B shows changes in the direction of polarization in a twisted nematic liquid crystal in a state where a supply voltage is applied to the electrode.

Here, the twisted nematic liquid crystal layer 68 includes regions of the layer 68a, 68b, and 68c, as shown in FIG. 6A, and when voltage is applied to the electrodes 67a and 67b in contact with the regions 68a and 68b, the optical relative property disappears, as a result, since a predetermined direction of incident light is maintained, as shown in FIG. 6B, the light is blocked by an attachable polarizing plate 71, the polarization direction of which is perpendicular to the polarization direction of the incident light, as shown in FIG. 6A. However, since no voltage is applied to region 68c, the polarization direction is rotated 90 ^° and light passes through the polarizing plate 71, as shown in FIG. 6A.

In more detail, when the liquid crystal optical modulator 44 ′ is in such a state that it has the same direction as the polarization direction rotated 90 ^° when the feed direction is not applied to it, incident light passes through the optical modulator. On the contrary, when a predetermined supply voltage is applied to it, having AC components controlled by a special waveform generator 144, since the optical relative property disappears, the light is blocked by a polarizing plate 71. In this case, the direction of polarization of the last outgoing light beam has a rotation of 90 ^o relative to direction of polarization of the first incident light beam, thereby this mode is called the positive mode or normal white mode.

 In FIG. 6B shows the state where voltage is applied to the optical liquid crystal modulator in the normal black mode, and FIG. 6D shows a change in the direction of polarization in a twisted nematic liquid crystal in a state when a voltage is applied to it.

 As shown in FIG. 6B, when voltage is applied to the transparent electrode 67c, and not to the transparent electrodes 67a and 67b, the switch SW 10 must be controlled. That is, the transparent electrodes 67a and 67b must always be controlled independently of the transparent electrode 67c.

In more detail, in the case where the direction of polarization of the attached polarizing plate 71 is perpendicular to the direction of polarization of the outgoing light passing through the twisted nematic liquid crystal layer (for comparison, in Fig. 6D, the case is shown where the voltage from the special-purpose signal generator 144 is not applied to the transparent electrodes 67a and 67b), that is, the polarization plate 71 is attached in such a way that its direction of polarization coincides with the direction of polarization of the incident light coming out the emitter from the twisted nematic liquid crystal layer changes the direction of polarization by 90 ^° and is blocked by the polarization plate 71. In this case, the liquid crystal layer with the polarization plate 71 is called the negative mode or the normal black mode.

 When a voltage having an AC component is applied to the electrodes of a twisted nematic liquid crystal layer 68 having a frequency and waveform during operation and bias that correspond to the control of the optical modulator on the liquid crystal, since the optical relative property of the liquid crystal indicator disappears, polarizing components are provided having the same direction of polarization as the incident light when light passes through the liquid crystal indicator, in as a result, a predetermined light leaves the polarizing plate 71 connected to the transparent exit plate 70. If the aforementioned twisted nematic liquid crystal layer 68 is used, it is possible to have the same direction of polarization between the last direction of polarization and the first direction of polarization.

 In FIG. 6F and 6G show the operational states of the optical modulator using a layer of liquid crystal dispersed in the polymer as layer 68.

 As shown in FIG. 6F, in the case where voltage is not applied to the transparent electrodes 67a and 67b, it is necessary to control the switch SW 10 so that the supply voltage is always applied to the transparent electrode 67c and at the same time the transparent electrodes 67a and 67b are connected and disconnected.

 In more detail, since light passing to regions of a liquid crystal dispersed in polymer 68a and 68b; in contact with electrodes 67a and 67b, to which no supply voltage is applied, is scattered, the amount of transmitted light is reduced. On the contrary, the light entering the region of the layer 68c in contact with the electrode 67c to which the voltage is applied does not scatter and passes through the output side.

 In this case, the ratio between the amount of light passing through the liquid crystal layer and the amount of scattered light satisfies the equation explained below.

 In addition, to increase the numerical aperture when voltage is applied to the transparent electrodes 67a and 67b, as shown in FIG. 6G, all incident light passes to the output side.

 Meanwhile, in the case of an optical reader for reading data from a disk with a high recording density, since a lens with a large numerical aperture is required, in the case when the aperture is large according to the diffraction theory, the beam size increases in the direction of polarization. In addition, in the case of using a plastic lens, since astigmatism due to birefringence of the material takes place in the direction of polarization, it is necessary to adjust the direction of polarization so that it coincides with the tangent track formed on the disk, as a result of which you can select the desired mode, since there is certain effect to increase the signal-to-noise ratio.

 In addition, in the case of an optical modulator 44 'with a twisted nematic liquid crystal layer 68, light leakage can occur in the light-blocking region when using the two above modes due to an error in the angle of rotation of the polarization due to an error in the gap between the transparent plates 66 and 70, errors regarding the initial direction of polarization of the incident light and installation errors of the polarizing plate 71, so it is difficult to achieve the work of the optical system. In addition, when using a liquid crystal dispersed in a polymer, since the scattered light falls from a region in which no voltage is applied, changes in the difference in operation can occur in it compared with the case when the light is practically blocked. The above change in operation, as shown in FIG. 8B may be expressed as a contrast coefficient (C. R) as follows when the light intensity of the light transmitting unit is taken as “1”.

Contrast Ratio = Js / Jt,
where Jt denotes the transmitted light intensity of the light transmitting unit "A" and Js denotes the transmitted light intensity of the light blocking unit "B" or the light scattering unit.

 In FIG. 8A shows the variation in jitter of pits as a function of the contrast ratio; FIG. 9C shows the variation in crosstalk as a function of contrast ratio, and in FIG. 9D shows the dependence of the reproduction gain on the contrast ratio.

The effective range of the contrast coefficient in relation to the transmitted light intensity of the blocking unit can be expressed as follows
0 ≤ contrast ratio ≤ 0.1
Since the light beam passing through the optical modulator 44 ^' on the liquid crystal has different input diameters according to whether the optical modulator 44' is brought into operation or not, the numerical aperture changes and the lens 25 focuses the light to form a focal point on the surface recording the data of the disc 10. Moreover, since it is necessary to adjust the position of the focal point and since the distance L1 between the recording surface of the disc having a thickness of 0.6 mm and the lens 25, which is located in the initial position, is less than the distance L2 between the supporting surface of the drive 40 having the optical modulator 44 'and the lens, and the side wall of the lens 25 on the disk, when the drive unit 25 vibrates up and down from the initial position in the playback mode, a point corresponding to the radio frequency signal of the disk having a thickness of 0.6 mm, and then another point appears corresponding to the radio frequency signal of the disc having a thickness of 1.2 mm.

 If there is a large change in the direction applied to the focusing coil of the drive 40, since a relatively high voltage is required, where Vs denotes a specific voltage applied to the focusing coil at the point at which the radio frequency signal of the disk having a thickness of 0.6 mm occurs, and voltage Vc denotes a specific voltage applied to the focusing coil at a point at which a radio frequency signal of a disk having a thickness of 1.2 mm occurs, it is possible to control the initial focus point in various disks by setting Vc and Vs as the magnitude of the input zero bias voltage of the focus control unit.

 In FIG. 10 shows a connection diagram of the circuit part "B" used in the first embodiment of the proposed optical reader.

 As shown in FIG. 10, when the play key (not shown) is pressed at the output of microcomputer 800, a control signal is output to switch SW 1. If the bias resistance of the amplifier AMP2 is equal to the resistance of the CD, Rc is connected, and in the case of a digital video disc, Rs is connected .

 When applying a constant bias voltage to the focusing coil 605 in the focus control unit 605, the drive 40 is moved to the disk. After moving the actuator 40, the microcomputer 800 closes the switch SW 2 connected to the generator 30a of the numerical aperture control unit 400 to drive the optical modulator 44 ', thereby reducing the effective numerical aperture. That is, the periphery of the optical modulator on the liquid crystal 44 'is obscured.

 After reducing the effective numerical aperture, the microcomputer 800 recognizes the disk 10, closes the switch SW 3 of the engine control unit 700, selects a specific circuit for the variable resistance Rl and reduces the rotation speed of the motor 710. The motor 710 is connected to a power amplifier 715 connected to the engine control unit 720.

 Meanwhile, the microcomputer 800 closes the switch SW 4 of the focus control unit 650, sends a signal in the form of triangular pulses from the generator 655 to the drive 40 and causes the drive 40 to oscillate. In this case, if the switch SW 4 is closed, the open state of the switch SW 6 is maintained and if switch SW 4 opens, switch SW 6 closes.

 The switch SW 5 is actuated in accordance with the operation of the switch SW 1. In the case of a CD, the reproduction signal processing unit 500 controls the amplification factors G 1, G 2, and G 3 and in the case of a digital video disc, it controls the amplification factors G 1, G 2 and G 3.

 Let us now describe in more detail the processing unit of the reproducing signal 500.

 In FIG. 11A shows the internal structure of the photodetector, and FIG. 11B is a diagram of a reproduction signal processing unit.

 As shown in FIG. 11A, the photodetector 28 includes three elements 28a, 28b and 28c, of which the element 28a is located in an intermediate position of the photodetector and is divided into 4 parts. A beam falling into each of the elements 28a, 28b and 28c, as shown in FIG. 11B is converted to an electrical signal using the photoelectric effect. That is, the electrical signals a, b, c, d, e, and f are processed together with the radio frequency signal, the focus error signal, and the follow error signal in the RF signal calculation unit 555, the focus error calculation unit 560, and the follow error calculation unit 565, respectively, so that disc type is recognized by the logic circuit of disc identification block 550.

The analog switching grating 570 (switch SW 5 in FIG. 10) of the reproduction signal processing unit receives a signal in accordance with the operational signal received by the photodetector unit 500, determines the corresponding chain, reads a digital video disc and applies the signal from the output terminal of the operational amplifier (not shown ) having a gain G (in Fig. 11B, the coefficients G 1, G 2 and G 3 are indicated). In the case of reading a compact disc with a low recording density, the array 570 applies the output signal of the operational amplifier. In this case, the relationship between the amplification factors G and G 'can be written as follows
G ≤ G '.

 The signals received at the output of the operational amplifier are converted into a radio frequency signal, a focus error signal, and a follow-up error signal by the computing unit of the radio frequency signal 555, the computing unit of the focus error 560, and the computing unit of the following error 565 and transmitted to the digital signal processing unit 750, the focus control unit 650, and a follow-up control unit 600, respectively.

 In FIG. 12 is a block diagram of a disk identification unit.

 When a light spot is formed on the data recording surface (not shown) of the disk 10, since it is necessary to adjust the focus position in accordance with the identification of the type of disk, as shown in FIG. 12, the microcomputer 800 moves the drive 40 to the disk) reduces the numerical aperture by driving an optical modulator on liquid crystal 44 'and drives the spindle motor 710 of the engine control unit at a constant speed.

 When the above conditions are met, the drive 40 oscillates and it is determined whether an RF signal has been generated. It can be determined that an RF signal is generated (that is, in the case of a disc having a thickness of 1.2) or an RF signal but is generated (that is) in the case of a disc having a thickness of 0.6 mm).

 1) In the case of generating a radio frequency signal, the motor 710 is controlled at a constant linear speed and the number of reference revolutions is controlled by the 720 motor control circuit. Then, the focus and follow control signals are transmitted to the focus control unit 650 and the follow control unit 600, respectively, through the reproduction signal processing unit 500. Then the reader reads the signal.

 2) In the event that an RF signal is not generated, the actuator 40 returns to its original position and the effective numerical aperture is increased by converting the actuation of the optical modulator on the liquid crystal 44 '. In addition, the drive oscillates. Then it is determined whether or not the RF signal is generated. In this case, if the RF signal is not generated, it is determined whether the disk has an error or the disk is missing. In the case of generating a radio frequency signal, the motor 710 is controlled at a constant linear speed and the number of reference revolutions is controlled by the 720 motor control circuit. Then, the signals are read by controlling focus and following by controlling gain values.

 Let us now describe in more detail the case when a radio frequency signal is generated.

The microcomputer 800 controls the switch SW 1 and sets the drive to its initial position, so that the bias resistance is Rc and when a high frequency is generated during the oscillation of the drive 40, a voltage is applied to the comparator C1 through the DC detection unit, consisting of the R1, R2, C1 and C2 units disc identification 550, and when the magnitude of the voltage applied to the comparator C1 exceeds the value of the reference voltage set by the resistances R _t and R3, it is recognized that the high frequency of the radio frequency signal exceeds the effect The same value and the microcomputer recognizes that the disc is a CD type.

When the disc type is detected, after the microcomputer 800 opens the switch SW 4, while maintaining the state of the switches SW 1, SW 2 and SW 5, in the focus control unit 650, the follow control unit 600, the engine control unit 700, the control unit numerical aperture 30 and the processing unit of the reproducing signal, the microcomputer 800 closes the switch SW 3 after opening the switch SW 4 and provides a control signal to the engine control unit and gives a focus error signal about the output of the processing unit a supply signal 500 to the focus control unit 650 by closing the switch SW 6 and provides a follow error signal to the follow control unit 600. In addition, when the switch SW 3 is closed in the engine control unit 700, the output of the engine control signal from the ball signal processing unit 750 is supplied to the block engine control 700 to control its constant linear speed. However, if the RF signal is not generated during the oscillation of the drive, the microcomputer 800 controls the switch SW 1 so that the bias resistance is R _s and restores the position of the actuator 40, opens the switch SW 2 to stop the operation of the optical modulator on liquid crystal 44 'and increases the effective numerical aperture. In addition, the microcomputer 800 closes the switch SW 4 and a wave is generated in the form of a sequence of triangular pulses from the output of the generator 655 to oscillate the actuator 40. When performing the above operation, a control signal is provided to select a circuit having a certain gain corresponding to a high recording density disk.

 When an RF signal is generated during the oscillation operation of the drive 40, the comparator C1 outputs a disc recognition signal to the microcomputer 800, and the microcomputer 800 maintains the state of the switches SW 1, SW 2, and SW 5. In addition, the engine control unit 720 is controlled to regulating a constant linear speed using a signal from a transducer.

 When the switch SW 6 is closed, a Focus Error (FES) signal is supplied to the Focus control unit 650, and a Follow Error (TES) signal is supplied to the follow control unit 600 to control focus and follow.

 However, when the radio frequency signal is not generated, this means that there are no disk errors or the disk is missing and an error signal is output and the operation stops.

 Let us now describe in more detail the case when an optical modulator such as an iris diaphragm is used instead of an optical modulator on a liquid crystal as a control unit for a numerical aperture.

 In FIG. 13 shows a first embodiment of an optical reader of the invention.

 As shown in FIG. 13, numeral 130 denotes a video player board. On one side of the board 130 is a transfer engine of the reader 132 for carrying out its transfer. A first gear 136 is mounted on the upper part of the shaft 134 of the engine 132, which engages with the second gear 138. In addition, a third gear 139 is located on the upper part of the second gear 138, which engages with the gear rack 140 attached to the holder 122 for transmission to it engine driving force 132.

 In addition, the base of the reader 100 is located on the upper part of the holder 122, and the holder 122 is supported by a shaft 124. In addition, a shaft 110 is located at both ends of the base 100.

 In FIG. 14 shows the base of the reader of FIG. 13.

 As shown in FIG. 14, a predetermined cutout 105 is made in the central part of the base 100. A communication section 108a is formed in the central part of the cutout 105 and a diffraction grating 24 and a beam splitter 23 are formed on the part of the section 108a.

 On the side of the beam splitter 23 there is a protrusion for fixing the lens of the photodetector 27. The lens 27 is mounted in a cylindrical holder 127a, on the lower part of which an opening 127b is made, where the protrusion 115 enters. In addition, an opening 107a is made in a predetermined part of the side wall 100a of the base 100. . A photodetector 28 is inserted into the hole 107a.

 An opening 108 for an optical modulator is formed in the inner side wall of the cutout 105.

 In FIG. 15 shows a holder 122 connected to a base 100.

 As shown in FIG. 15, the holder 122 is located at the bottom of the base 100 and serves to carry it. The holder 122 is a U-shaped plate and a flat spring 124 is located on the upper part of the stepped side wall of the holder 122, which serves to fix the shaft 110 of the base 100. An opening 128 is made on the upper surface 123 of the side wall 122a. In addition, an opening is made in the flat spring 124 124a corresponding to the hole 128. The flat spring 124 is attached to the side wall 122 of the holder 122 with a screw 126. At the same time, a shaft 110 is placed on the lower cutout 123. In addition, a hole is made in the predetermined central part of the base 125 of the holder 122. 125a. An aperture 125a of the base of the optical modulator 174 shown in FIG. 16, which is fastened with a screw 127.

 We now describe an optical iris-type optical modulator installed in the hole 108 shown in FIG. fourteen.

 As shown in FIG. 16, an iris diaphragm-type optical modulator 160 includes first and second flaps 162 and 164 and a cover 168 that is attached to the upper part of the base of the optical modulator 166. At the base 166 there are two slotted holes 170 and a round hole 172. In addition, between the two holes 170 is made a number of small holes 173, spaced at some distance from each other.

 The first and second flaps 162 and 164 have guide holes 162a and 164a and holes 162b and 164b. In addition, the first sash 162 has a semicircular cutout 162c with an open side, and the second sash has a cutout 164c.

 On one side of the base of the optical modulator 166, a fastener 174 protrudes outward, which serves to attach the base 166 to a holder (not shown). There are protrusions 175) above and below the hole 172 in the base of the optical modulator, which serve to enter the first and second wings 162 and 164 into the guide holes 162a and 164a. In addition, there are two projections 166d on the outer side wall 166c of the base 166. The protrusion 166d is inserted into the hole 168d of the fastener 168 from the cover of the optical modulator 168.

 On the lower part of the base 166, an engine 180 is installed having a protruding shaft 182. On the upper part of the engine 180, two bearings 184 are located at a certain distance from its shaft 182. The shaft of the engine 182 is inserted into the central hole 185a of the rotor 185. The rotor 185 includes two protruding support shafts 188 The support shafts 186 are inserted into the slotted holes 170 made in the base 166, and the first and second blades 162 and 164 are sequentially put on them. After that, the first and second blades can be moved in the right and left directions in accordance with the drive Follower 180.

 In the lid 168 there is a round hole 169 and two slotted holes 167, each of which is made in a predetermined part relative to the base 166. Between the slotted holes 167 there are a number of small holes 163. In addition, on both sides of the cover 168 there are two fasteners 168c for fastening to one assembly with a base 166. The fasteners 168c have rectangular holes 168d. The holes 168d include protrusions 166d formed on the outer wall 166c of the base 166.

 In FIG. 17A and 17B show an optical modulator for use with a CD and a digital video disc, respectively.

 In the case of using a small numerical aperture, as shown in FIG. 17A, it is necessary to use an amount of light overlapping region “A” in the case of using an enlarged numerical aperture, as shown in FIG. 17B, it is necessary to use an amount of light overlapping region “B”.

 1) The case of using a small numerical aperture (Fig. 17A).

 First of all, when the motor 180 is driven, the rotor 185, operatively connected to the shaft of the motor 182, is driven. In this case, the support shafts 186 installed at both ends of the rotor 185 become movable within the slot bore 170. In the case of a small numerical aperture, when the support a shaft 186 entering the hole 162b of the first leaf 162 moves to the right along the slot hole 170 by half its length, and a second supporting shaft 186 entering the hole 164b moves left along the slot hole 170, moving halfway through the length of the hole 164 b. Since the support shafts move in the opposite direction in accordance with the movement of the rotor 185, the first and second wings 162 and 164 move in the opposite direction from each other with respect to the movement of the support shafts 186.

 2) The case of using a large numerical aperture (Fig. 17B).

 First of all, when the motor 180 is driven, the rotor 185 is operatively connected operatively to the motor shaft 182. In this case, the support shafts 186 installed at both ends of the rotor become movable within the slot bore 170. In the case of a large numerical aperture, when the support the shaft 186 entering the hole 162b of the first leaf 162 moves to the right along the slot hole, and the second leaf 164 moves to the left along the slot hole 170 in which the support shaft 186 enters the hole 164b. The first and second wings move in the opposite direction.

 Although in FIG. 16 shows that the first and second wings are wing-shaped, they can take a different shape, assuming that their shapes do not interfere with each other and they accordingly control the amount of transmitted light.

 In FIG. 18 is a diagram of an optical reader using an iris diaphragm type optical modulator as a numerical aperture control unit.

 Since the circuit shown in FIG. 18 is similar to the circuit shown in FIG. 10, with the exception of the numerical aperture control unit, it will not be described. In addition, in FIG. 19 is a flowchart of an engine control method when an iris type optical modulator is used.

As shown in FIG. 18 and 19, when an optical modulator of the iris type is used as the numerical aperture control unit 30, when a polarized voltage is applied to the engine control unit, the optical modulator becomes open and when unpolarized voltage is applied, the optical modulator closes. The current i ₀ shown in FIG. 18, flowing to the detection resistance R10, has a positive value + t ₀ in the case of clockwise rotation of the motor, however, in the case of a counter-clockwise rotation direction, the current has a negative value of t ₀ .

 When the control signal of the microcomputer 800 ensures that the switch SW8 is in a high state and the switch SW10 is in a low state, a certain voltage + V appears at the output of the differential amplifier AMP4 and the NPN transistor Q1 becomes electrically conductive and a positive voltage is applied to the motor 330, causing the motor rotates clockwise. In this case, the optical modulator 160 opens. Then, when the optical modulator 160 reaches a certain position and is held in place by a restrictive element (not shown), an excessive load is applied to the engine so that a voltage level in excess of the normal state is applied to the engine 330. In this case, when the voltage level at the resistance R10 is higher than the threshold voltage of the diode D1, the current flows through the DC diode, allowing current to flow through the resistance N and a positive voltage is applied to the positive input terminal of the differential amplifier AMP5, as a result of which the output of the differential amplifier AMP5 is high condition. The microcomputer then recognizes the output according to the S-signal and allows the switch SW 8 to go low.

 Meanwhile, to close the optical modulator 160 (that is, when reading data stored on a CD), the switch SW 8 must be lowered and the switch SW 10 high, so that the output of the differential amplifier AMP4 becomes negative the voltage is V and the transistor Q2 becomes activated and a negative voltage is applied to the motor 330, as a result of which the motor 330 starts to rotate in the opposite direction. At the same time, the microcomputer 800 maintains the current state when the voltage of the S signal is low and when the optical modulator 160 is fully open and the motor 330 cannot rotate in the opposite direction, an excessive load is applied to the motor and a high voltage is applied to the resistance R10, while as negative voltage is applied to the input terminal of the AMP5 differential amplifier.

 Therefore, when the output signal increases, the microcomputer detects this and causes the switch SW 8 to go low and stops supplying voltage to the motor 330.

 In FIG. 20 shows a second embodiment of the proposed optical reader.

 The second embodiment of the optical reader has a similar construction as the first embodiment, with the exception of the AA optical system. Only the AA optical system will be described below.

 As shown in FIG. 20, the AA optical system includes a light source 41, for example, a laser diode, a diffraction grating 54 for diffracting the beam from the light source 41 and for generating A ± 1 diffracted light for the main beam and creating an automatic follow-up control system, collimating lens 55 to produce a parallel beam , a beam splitter 43 for transmitting light reflected by the disk 10a and for transferring light to the lens of the photodetector 47, a numerical aperture control unit 30 for changing the width of the beam incident on the disk, and for changing the effects A typical numerical aperture of the lens 45, the lens 45 for focusing the beam on the disk 10a and for receiving an optical signal modulated by the signal of the disk 10a, the drive unit 46 having a moving coil 46a, which serves to move the corresponding focus point in accordance with the type of disk, perform the control operation focus in accordance with the displacement of the location of the disk 10a and the execution of the follow-up control operation of the read beam, the disk 10a having at least two different thicknesses and at least ve different recording density, the photoreceiver lens 47 through which light passes modulated signal 10a recorded on the disk to the photodetector 48 and a photodetector 48 for converting an optical signal into an electrical signal.

 As the control unit for the numerical aperture 30 of the second embodiment of the present invention, there may be either an optical liquid crystal modulator or an iris type optical modulator. However, in the present embodiment, an iris is used to achieve the objectives of the second embodiment of the invention.

 In FIG. 21 shows a reader base of a second embodiment of the present invention.

 As shown in FIG. 21, the base, indicated by 200, has a rectangular cutout and a semicircular cutout section 204. In addition, there is an outwardly protruding shaft 209a that must be fastened to a predetermined portion of the board 130 (FIG. 13) mounted in the protruding portion 209 of the base 200 formed on its central part.

 At a predetermined location of the base 200, there is a rectangular plate-shaped support 202 for mounting a beam splitter 43 on it. At the rear of the beam splitter 43 there is a cylindrical holder 205, which serves to fix the collimating lens 55. On the bottom of the holder 205 there is an opening 205a for receiving the protrusion 215, located on the base 200 behind the stand placement 202. In addition, a removable collimating lens 55 is inserted into the holder 205.

 On the left side of the placement stand 202 there is a protrusion 216, which is inserted into the hole 226a of the holder 226, which serves to fix the lens of the photodetector 47. In addition, the lens 47 is removably mounted in the holder 226.

 In the central part of the base 200, a hole 209 is made for inserting an optical modulator such as the iris diaphragm 110 shown in FIG. 22. In a predetermined part of the side wall 248 of the base 200, an opening 248a is made for mounting a photodetector 48 therein. In addition, an opening 258a is made in the front side wall 258 of the base 200 for mounting a light source 41 therein.

 In a predetermined portion of the semicircular cutout 204, a rectangular plate-shaped folding mirror 208a may be disposed mounted on a placement stand 208.

 In FIG. 22 shows the relationship between the iris control and the actuator used in the second embodiment of the present invention, and FIG. 23 shows a holder movable in cooperation with the base of the reader.

 As shown in FIG. 22, the element 210 has a corner portion and an opening formed in a predetermined portion of the vertical wall 212, and a gear rack 216 formed on the horizontal wall 213 and having a predetermined number of teeth. The holder 250 is located in a predetermined part of the base 200 (Fig. 21) and serves for its transfer. As shown in FIG. 23, the holder is a U-shaped plate. A flat spring 254 is located on the upper part of the stepped side wall 252 of the holder 250, which serves to attach the base 200 to the holder 250. An opening 252a is formed in the upper surface of the side wall 252. A hole 256 is formed in the flat spring 254, matching the hole 252a. The flat spring 254 is attached to the side wall 252 of the holder 250 with a screw 258 and the base shaft 209a comes into contact with the flat spring 254 and the upper surface 253.

 In a predetermined portion of the side walls 252 of the holder 250, a mounting plate for the engine 260 to the engine 220 shown in FIG. 22 is mounted on the mounting plate 260. As shown in FIG. 23, the mounting plate 260 is attached by a series of screws 260a. In addition, as shown in FIG. 22, the engine 220 has a shaft 22 on which a helicoidal gear 224 is mounted. The gear 224 is engaged with one to three gears 227, 228 and 229 and through them is engaged with the gear rack 216 of the element 210. In addition, three gears 227, 228 and 229 come into contact with washers 227a, 228a and 229a and rings 227b, 228b and 229b that are worn on respective shafts 227c, 228c and 229c. Shafts 227c, 228c, and 229c are inserted into respective holes 237, 238c, and 239c. Reference numeral 218a denotes a stand for placing member 210.

 Let us now describe the work of the second embodiment of the proposed optical reader, capable of reading data from disks of various types.

 First of all, the light beam from the light source 41 passes through the diffraction grating 54 and is further divided to obtain a sub-beam, which is the first diffraction-limited beam, necessary for servo control following single-beam or 3-beam methods. However, in the case of the single-beam method, a diffraction grating may be absent.

 The beam is transmitted to the control element of the iris diaphragm 210 (Fig. 22) through the collimating lens 55.

 A liquid crystal or iris type optical modulator used in the first embodiment of the present invention as a numerical aperture control unit can be used for the same purposes in the second embodiment. However, in a second embodiment of the present invention, an iris control is used to control the numerical aperture.

 In FIG. 24 shows a third embodiment of the proposed optical reader with a laser communication device.

 As shown in FIG. 24, in a third embodiment of the present invention, an optical system is used with a laser communication device that is integral with the propulsion 360.

 That is, the mover 360 is integrally located in the optical system of the first embodiment of the present invention. The assembly with a photodetector and a laser diode shown in FIG. 24, as shown in FIG. 24 and 25, includes a light source 321, for example, a laser diode, which plays the role of a beam splitter. In addition, the laser communication device includes two photodetectors 322 and 324. That is, as shown in FIG. 25, the light source has a tapered surface 323, the photodetectors 322 and 324 and the assembly with the laser diode 353 are integral, so that data can be read from the photodetector by receiving light from the light source 321 and the assembly with the laser diode 355 through the prism 357, controlling the numerical aperture of the lens using the numerical aperture control unit and focusing the light on the disc data recording surface.

 The operation of the numerical aperture control unit is the same as in the first embodiment of the invention. In addition, servo control methods for following and focusing the optical reader with a laser communication device) are performed using the circuit shown in FIG. 26. That is, since the output of the photodetector 326 is the signal B- (A + C), the output of the photodetector 324 is the signal B '- (A' + C '), the difference signal between the photodetectors 326 and 324, as shown in FIG. 26 is a signal of "326-324".

 As described above, the proposed optical reader capable of reading data from various types of disks is designed to read data stored on a low density recording disc, a compact disc, or a high recording density digital video disc, regardless of the thickness of the disc, using the control unit numerical aperture.

 Translation of inscriptions to drawings.

FIG. 2:
1 - beam intensity,
2 - the main diffraction maximum,
3 - lateral diffraction maximum,
4 - position
FIG. 3 and 20:
400 - drive unit control unit numerical aperture,
500 is a block processing the reproducing signal,
550 - disk identification unit,
600 - block follow control,
650 - focus control unit,
700 - engine control unit,
750 - digital signal processing unit,
800 - microprocessor.

FIG. 8A:
1 - degree of trembling,
2 - contrast ratio.

FIG. 9A:
1 - crosstalk
2 - numerical aperture of the lens.

FIG. 9B:
1 - signal intensity
2 - 11T signal intensity,
3 - 3T signal intensity,
4 - numerical aperture of the lens.

FIG. 9c:
1 - crosstalk
2 - contrast ratio.

FIG. 9D:
1 - gain of the reproducing signal,
2 - 11T signal,
3 - ratio of 3T / 11T signals,
4 - 3T signal,
5 - contrast ratio.

FIG. ten:
30a - generator
720 - engine control unit,
750 - digital signal control unit,
800 is a microcomputer.

FIG. 12:
1 - 1 / move the disk to the drive,
2 / decrease the numerical aperture of the lens using
liquid crystal optical modulator.

 3 / maintaining normal disk speed.

2 - oscillation of the drive,
3 - "YES",
4 - a radio frequency signal is generated,
5 - "NO"
6 - rotation of the spindle motor using constant linear speed control,
7 - 1 / focus control,
2 / follow control,
8 - read signal
9 - 1 / moving the drive to its original position,
2 / increase the effective numerical aperture by turning off the optical modulator on the liquid crystal.

10 - no disk errors or no disk,
11 - control of the constant linear speed of the spindle motor.

FIG. 18:
160 - optical modulator
720 - engine control unit,
750 - digital signal processing unit,
800 is a microcomputer.

FIG. 19:
1 - CD
2 - a CD or a digital video disc,
3 - digital video disc,
4 - low condition
5 - high condition,
6 - "NO",
7 - "YES",
8 - return.

Claims (51)

 1. An optical reader capable of reading data from a disk of various types, comprising a light source, a beam splitter for passing through or splitting the beam from the light source, a lens for collecting the beam on the disk, a numerical aperture control means and a photodetector for receiving the beam reflected by the disk , and missed by the splitter beam, characterized in that the means for controlling the numerical aperture is configured to control the effective value of the numerical aperture of the lens for the process of focusing the beam on disks of different thicknesses.  2. The device according to claim 1, characterized in that it contains means for processing the reproducing signal for transmitting certain signals to the following control unit and the focus control unit with respect to the electric signal at the output of the photodetector; disc identification means for identifying discs having different thicknesses using an electrical output of a reproducing signal processing means; a drive unit for controlling the numerical aperture for actuating the means for controlling the numerical aperture with respect to a particular disk selected among disks having different thicknesses; disk identification means; a motor control unit for controlling a spindle motor in accordance with a thus selected disk; and a microcomputer for selectively controlling a numerical aperture control unit, a focus control unit, a follow-up control unit or a motor control unit in accordance with the output signal of the disk identification means.  3. The device according to claim 1, characterized in that between the beam splitter and the light source there is a diffraction grating and between the beam splitter and the photodetector there is a photodetector lens.  4. The device according to claim 2, characterized in that in a given part of the drive unit there is a lens and a numerical aperture control, movably connected to each other.  5. The device according to claim 1, characterized in that the disk is a compact disc having a thickness of 1.2 mm, or a digital video disc with a high recording density having a thickness of 0.6 mm  6. The device according to claim 1, characterized in that the means for controlling the numerical aperture is located between the light source and the lens in the light path.  7. The device according to claim 1, characterized in that the means for controlling the numerical aperture is integral with the light source.  8. The device according to claim 1, characterized in that the means for controlling the numerical aperture is integral with the lens.  9. The device according to claim 4, characterized in that the drive unit comprises a follow-up coil wound around the receiving part of the lens, a clamp for fastening to the receiving part of the lens and the follow-up coil, and the base of the drive unit for mounting the clamp.  10. The device according to claim 9, characterized in that in the Central part of the base of the drive unit a hole is made corresponding to the optical path of the optical modulator on a liquid crystal.  11. The device according to claim 1, characterized in that the effective numerical aperture value controlled by the numerical aperture control is in the range of 0.27 - 0.5.  12. The device according to claim 1, characterized in that the means for controlling the numerical aperture is an optical modulator on a liquid crystal.  13. The device according to item 12, wherein the liquid crystal optical modulator comprises a plurality of transparent plates, a liquid crystal layer located between the transparent plates, and a plate on which patterns of a plurality of transparent electrodes are formed.  14. The device according to item 13, wherein the liquid crystal layer contains a liquid crystal dispersed in the polymer.  15. The device according to item 12, wherein the liquid crystal optical modulator comprises a plurality of transparent plates and a plate on which patterns of a plurality of transparent electrodes are formed, and a polarizing plate.  16. The device according to clause 15, wherein the liquid crystal layer contains a twisted nematic liquid crystal.  17. The device according to p. 15, characterized in that the transparent electrode pattern on the specified plate is made in the form of an annular strip to increase optical efficiency.  18. The device according to clause 15, wherein the liquid crystal optical modulator is designed to control a numerical aperture by applying an electrical control signal between the transparent electrodes.  19. The device according to clause 15, wherein the transparent electrode is located in a given part of the plate to change the diameter of the light beam on the optical path to control the numerical aperture.  20. The device according to clause 15, wherein the liquid crystal optical modulator comprises a light blocking element having a transparent electrode and a light transmitting element, wherein by controlling the amount of voltage applied to the transparent electrode, the light blocking element is turned on and off.  21. The device according to claim 20, characterized in that the contrast coefficient is in the range 0 - 0.1, wherein the contrast coefficient is equal to the ratio Js / Jt, where the light intensity of the light transmitting element is taken as I, Jt denotes the intensity of the light transmitted through light transmitting element, and Js denotes the intensity of light transmitted through the light blocking element.  22. The device according to claim 2, characterized in that the means for processing the reproducing signal comprises a unit for calculating the radio frequency signal of the photodetector for processing the output signal of the photodetector, a unit for calculating a follow error and a unit for calculating the focus error.  23. The device according to item 22, wherein the means for processing the reproducing signal contains an analog switching lattice.  24. The device according to claim 2, characterized in that the follow-up control unit connected to the reproducing signal processing means comprises a voltage amplifier for amplifying a predetermined voltage in response to a follow-up error signal at the output of the reproducing signal processing means and a supply voltage amplifier.  25. The device according to claim 2, characterized in that the focus control unit connected to the reproduction signal processing means comprises a voltage amplifier for amplifying a voltage in response to a focus error signal at the output of the reproduction signal processing means and a supply voltage amplifier.  26. The device according A.25, characterized in that the voltage amplifier contains a switch connected to the microcomputer to control the resistance and to control the bias voltage applied to it, in accordance with the type of disk.  27. The device according A.25, characterized in that the voltage amplifier contains a switch and is electrically connected to the generator.  28. The device according to claim 2, characterized in that the means of identifying the disk contains a comparator for identifying the type of disk in accordance with the radio frequency signal at the output of the processing means of the reproducing signal.  29. The device according to claim 2, characterized in that the engine control unit comprises a switch for recognizing a signal at the output of the digital signal processing unit and the microcomputer and for outputting a certain voltage, an engine control circuit connected to the switch, a power supply amplifier connected to the control unit motor, and spindle motor.  30. The device according to claim 2, characterized in that the means for controlling the numerical aperture comprises a generator.  31. The device according to claim 2, characterized in that the control tool for the numerical aperture is an optical modulator type iris diaphragm.  32. The device according to p. 31, characterized in that the optical modulator type iris includes movable first and second wings, the base of the optical modulator for installing the first and second valves, a lid mounted on top of the base, forming a single unit, and an engine for driving first and second sash.  33. The device according to p, characterized in that in the first and second wings are made guide holes aligned in the vertical direction.  34. The device according to p. 32, characterized in that the base of the optical modulator includes a mounting part located to it at a predetermined angle, used to attach to one side of the holder, on its upper surface there is a slot hole made on one side of the slot hole, an opening made on the opposite side of the slot hole to form a predetermined gap therein along the movement of the wings, and two protrusions on both sides thereof.  35. The device according to clause 34, wherein the base of the optical modulator contains a rotor and is connected to the engine.  36. The device according to clause 35, wherein the rotor contains two support shafts and has a hole in the Central part.  37. The device according to clause 35, wherein the engine has an axis and supporting protrusions located on both sides of it.  38. The device according to p, characterized in that the cover of the optical modulator has a hole and two slotted holes aligned with the slotted holes of the base of the optical modulator, and two mounting parts formed on its both sides.  39. The device according to claim 2, characterized in that in its circuit part, when using an optical modulator such as an iris diaphragm as a means of controlling a numerical aperture, it comprises a motor electrically connected to the optical modulator, a first differential amplifier for receiving a signal from the output of the microcomputer, a series of transistors, each of which is connected to the output terminal of the differential amplifier, and a second differential amplifier, electrically connected to the diode in accordance with the output signal t anzistorov.  40. The device according to § 39, wherein the second differential amplifier contains a grounded resistance between the circuits in which there are two diodes.  41. An optical reader capable of reading data from various types of disks, containing a light source designed and intended to emit a light beam, a collimating lens designed and designed to collimate a light beam to give it parallelism, a diffraction grating located between the light source and the collimating a lens, a lens for collecting a light beam onto an optical disk, a numerical aperture control means, a photodetector assembly, designed and intended for receiving light reflected by the optical disk in accordance with the incident light beam, and to generate a first signal in response to the light reflected by the optical disk, a beam splitter designed and designed to transmit the beam from the light source to the lens and to reflect light reflected by the optical a disk, to a photodetector, characterized in that the numerical aperture control means is configured to control the numerical aperture of the lens by controlling the size of the light beam reaching the lens, while the follower control unit, the focus control unit, the reproducing signal processing means for transmitting the second signal to the follower control unit and the focus control unit, respectively, in response to the first signal from the photodetector assembly, disk identification means for identifying the optical disk by the thickness of the optical disk are introduced and for generating a corresponding third signal based on the second signal from the processing means of the reproducing signal, the drive device with numerical aperture control means for actuating numerical aperture control means in response to identifying an optical disk by its thickness with a disk identification means, a spindle motor, a motor control unit for controlling a spindle motor in accordance with an optical disk identification, and a microcomputer designed and designed for selectively controlling at least one of the numerical aperture control means, a focus control unit, a control unit with edovaniem and engine control unit in accordance with a third signal from the disc identifying means.  42. The device according to paragraph 41, wherein the means for controlling the numerical aperture is an optical modulator on a liquid crystal.  43. The device according to paragraph 41, wherein the means for controlling the numerical aperture is an optical modulator type iris diaphragm.  44. The device according to paragraph 41, wherein the means for controlling the numerical aperture is a means with an iris diaphragm.  45. The device according to item 44, wherein the means with the iris diaphragm is a staple-shaped element having vertical and horizontal parts, and a gear rack protruding outwardly on the horizontal part.  46. An optical reader capable of reading data from various types of disks, comprising a mechanical system and an optical system including a light source, a photodetector, a lens for collecting light on a disk, and a numerical aperture control means, the mechanical system including a motor, characterized in that a prism is introduced into the optical system to form the light path from the light source to the photodetector, which are made in the form of a single assembly, the means for controlling the numerical aperture It is possible to control the numerical aperture of the lens to carry out the process of focusing the beam on disks of different thicknesses, and the engine of the mechanical system is movable and is integral with the optical system.  47. The device according to item 46, wherein the numerical aperture control is located between the assembly of the light source and the photodetector and the prism.  48. The device according to item 46, wherein the means for controlling the numerical aperture is an optical liquid crystal modulator.  49. The device according to item 46, wherein the means for controlling the numerical aperture is an optical modulator type iris diaphragm.  50. The device according to item 46, wherein the means for controlling the numerical aperture is a tool with an iris diaphragm.  51. The device according to item 46, wherein a focusing coil and a tracking coil are mounted on both sides of the engine to control focus and follow, respectively.

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