Controlled system for focussing a read-out light beam

[Detailed Description of the Invention]

Optical [ of the move track where the present invention is held on the magnetic disk or tape in which information is recorded ] '' It is related with-like read-out and related with the control device for reading, if it says in more detail, and converging an optical beam on a track. A difficult technical problem arises in respect of correctness, therefore optical read-out of the information recorded with high density is Read-. Various kinds of devices are proposed for the purpose of taking out, reading with a track in relation to the axis of a track within a perpendicular plane to a beam, and making a head position correctly relatively. It reads for a certain use and, as for a beam, information is Record one. The accuracy which converges very correctly on the track carried out, and is demanded failing in Mustache is a 1-micron order almost like a front. Various devices are used for this object. Range finding S of assistance [ like a capacitance device ] in which these devices are A device is used. One polar plate of this capacitance device is connected with the focusing lens which moves, and the polar plate of another side is constituted by the meta-Rise(ed) thing on a track board. Therefore, change of the capacity of Entensa constituted by doing in this way serves as a convergence error signal. Other Wear 0 Place uses the fill-in flash beam from which it separated from the optic axis of the focusing lens. With this device, an error signal is obtained by a pair of optical power detectors, and differential amplification. these differential gears can be set to positioning of a receptor (for example, the above-mentioned optical power detector) -- systematic -- it unites zero and produces an error. 5 The object of the present invention is to provide the control device for reading to the track ground in which information is recorded and which moves using the signal itself include information, and converging an optical beam, in order to detect a convergence error. In the control device for according to the present invention, reading on the substrate on which data is recorded and which moves, and converging an optical beam, The device which generates a periodic pilot electricity signal, and the above-mentioned optical beam are converged on the above-mentioned substrate, The object lens which runs by the object lens which modulates the optical beam by above-mentioned Zeta, and which moves in parallel with an optic axis under an operation of Then and the above-mentioned pilot signal, An electrooptic device for changing into the electric read-out signal showing the above-mentioned data the optical beam modulated [ above-mentioned ], The control device converged on the substrate which moves a read-out optical beam provided with the device which generates a convergence error signal comparing the above-mentioned pilot signal with the above-mentioned read-out signal, and the device which add the above-mentioned convergence error signal to the above-mentioned object lens, and to which it makes the above-mentioned convergence perform is obtained. Hereinafter, with reference to drawings, the present invention is explained in detail. First, with reference to Drawing 1, information is recorded on surface 41 of a substrate, i.e., data carrier 4, and it moves to the direction shown by an arrow. This information is optically read by the 1st assembly, and is Praying(ed) by it, and a beam converges by the 2nd assembly. The 1st assembly is constituted by object lens 2 on which it is supported with attachment instrument 21 and parallel optical beam 1 for information read-out is converged, optical power detector 3, and amplifier 5. Optical beam 1 has optic axis 11, object lens 2 is arranged so that the central axis may be in agreement with the above-mentioned optic axis 11, and when convergence is performed correctly, optical beam 1 is converged on the place of point 22 on the surface of substrate 4. Optical power detector 3 is changed into the electric signal which reads the optical beam modulated by the above-mentioned information, and it calls signal v, and amplifier 5 amplifies read-out signal V. The amplitude of read-out signal v is related to a convergence error. Read-out signal V can be made into a periodic signal, for example. The phase or frequency of the periodic signal expresses the coded information which is recorded on substrate 4. The output signal of amplifier 5 is applied to channels 51 and 52. Channel 51 performs a decipherment and processing of information and channel 52 tells an output signal to the 2nd above-mentioned assembly. Envelope detection machine 6 with which the 2nd channel of the 2nd above-mentioned channel receives signal v from 52, Synchronous detection machine 7 which receives the output signal of envelope detection machine 6 in the one input side, Low-pass filter 10 connected to the output side of this synchronous detection machine 7, and switch 91 controlled by threshold relay 9, 3 input adding machine 50, motor 60, and oscillator 30 that is connected to the 2nd [ of adding machine 50 ] input side, and generates periodic pilot signal P, Source 40 of variable direct-current voltage connected to the 3rd [ of adding machine 50 ] input side, and phase converter 20 which carries out the Transfer phase of the pilot signal generated by oscillator 30, and gives an output to the 2nd [ of synchronous detection machine 7 ] input side, It comprises beak detector 8 which gives signal v of the level which reads from channel 52 and is in threshold relay 9 in response to signal v. One point of contact 92 of switch 91 is connected to the output side of filter 10, and point of contact 93 is grounded. The 1st [ of 3 input adding machine ] input side is connected to the traveling contact of switch 91. Under control of the signal given from adding machine 50, motor 60 operates attachment instrument 21 of object lens 2 in the direction of arrow 61 in parallel with optic axis 11. If possible, the above-mentioned pilot signal P is made into the sine wave signal of cycle T. Under control of pilot signal P, this 2nd assembly operates so that reciprocating movement of cycle T parallel to optic axis 11 may be given to object lens 2. Therefore, it reads, and the amplitude of signal v changes periodically, and signal V modulated by doing in this way is compared with signal P, and generates a convergence error signal. This comparison is performed in three stages. Envelope detection machine 6 detects the envelope of signal v to the 1st first, and (added via phase converter 20 from oscillator 30) it performs synchronous detection between pilot signal P and the envelope of signal V (synchronous detection machine 7), Finally, low-pass filter 10 removes a high frequency ingredient so that only a convergence error signal may be left behind. A convergence error signal is used in order to amend object lens 20 position via adding machine 50 and motor 60. Drawing 2 shows the waveform of various kinds of above-mentioned electric signals. Curve 23 expresses the envelope of read-out signal V given with envelope detection machine 6. The horizontal axis of this curve 23 is optic axis 11. Curve 23 has peak A point ZA on a horizontal axis. Point ZA is equivalent to the right converging point 22 on surface 41 of substrate 4 which only the distance of ZA has separated from the center of object lens 2. As for curve P, a cycle shows sine wave pilot signal P of T as a function of time t. Curve 24 is for showing why (A point) and read-out signal v come to include the periodic signal of periodic T / 2, when convergence is performed correctly. Although signal V has cycle T equal to the cycle of signal P at the time of - [ have ] to which convergence performs curve 25 correctly, i.e., when object lens 2 is on the point that only the distance corresponding to horizontal axis ZB separated from surface 41 of substrate 4, It is a graph for explaining why the periodic function which is not necessarily equal to the phase of signal P is included. When curve 26 has object lens 2 in inaccurate convergence position ZC and the amplitude of signal V corresponds to C point, it is shown how signal V includes the periodic signal of cycle T. A phase differs only in pi from the signal which shows this signal to curve 25. Points D and E on signal v corresponding to points Z2 and Z1 of a horizontal axis appoint a field of operation. The function of this field of operation is explained later. Synchronous detection machine 7 has input sides E1 and E2, and a cycle receives the periodic signal of T in input side E1, The output signal which contains a part flowed in one direction when the signal which will generate the output signal which does not contain a part flowed in one direction if a cycle is applied to input side E2 for T/2 of signals, and is added at input side E1, and the signal of the same cycle T are added at input side E2 is generated. In the case of the latter, the polarity of an output signal is positive when the phase contrast of input signals E1 and E2 is O, and it becomes negative at the time of pi. Synchronous detection machine 7 can be constituted as a signal multiplier in fact. In the device shown in Drawing 1, low-pass filter 10 is provided in order to obtain a convergence error signal. This convergence error signal can be used in order to amend the position of object lens 2 directly via adding machine 50 and motor 60. Cutoff frequency of low-pass filter 10 should be theoretically made lower than the frequency of signal P, and 1/5 of the frequency of the frequency of signal P is used in fact. The device shown in Drawing 1 also contains phase converter 20. The function of this phase converter 20 is compensating phase transition especially caused by the response time of motor 60 to the electric command signal given to motor 60 from adding machine 50. The frequency and amplitude of the pilot signal should be chosen so that the characteristic of the information currently recorded may not be affected. Peak detector 8 formed in the device shown in Drawing 1, threshold relay 9, switch 91, and source 40 of variable direct-current voltage are used when a device is acquisition operational mode. It is distantly [ from surface 41 ] separated from this operational mode of converging point 22 following introduction of new data career 4, for example. Therefore, when a point operating [ average ] is on the outside of a field of operation between point Zl on a horizontal axis, and points D and E respectively corresponding to Z2, it corresponds. In this case, the intensity of signal V is very weak and peak detector 8 is, The Sawa wave(ed) direct current signal is generated so that it may not contain, so that the output can detect the amplitude modulation ingredient of the same frequency as the frequency of pilot signal P, therefore threshold relay 9 may ground the traveling contact of switch 91 via fixed contact position 93. Therefore, in order to amend the position of object lens 2, it is required to adjust source 40 of direct-current voltage, until signal v obtains sufficient amplitude for threshold relay 9 contacting the traveling contact of switch 91 to fixed contact 92, and filter 10 making it connect with adding machine 50. It is possible to constitute so that the display in which the time when time, i.e., control, when switching is performed is performed is shown may be combined so that this device can be made to finish the manual regulation performed using direct-current power supply 40. In the example shown in Drawing 1, read-out of information is performed by the penetration of light and information is recorded on upper surface 41 of substrate 4. Of course, the device of the present invention can be applied also like the read-out art by reflection, and can be applied to any information or a data recording method. Along record of the information is carried out to the back of substrate 4 on track 42 as an example at Drawing 3, and the example to which read-out is carried out by reflection of light is shown. For this reason, substrate 4 has metal layer 43 behind track 42, and forms optical separator 32 made to incline at an angle of 45 degrees as opposed to optic axis 11 above lens 2. The function of metal layer 43 is reflecting a read-out optical beam, and the function of optical separator 32 is bending the reflected light to the direction of optical power detector 31. Since the remaining elements of the device shown in Drawing 3 are the same as the element used with the device shown in Drawing 1, they have omitted illustration in Drawing 3. Drawing 4 shows the modification of the device shown in Drawing 1. In this example, object lenses 27 and 28 of two sheets are used instead of object lens 2 which moves. Intermediary To have [ as ] which 28 attaches only one side among these object lenses, is held with instrument 21, and moves to direction of Along arrow 61 at optic axis 11. Although the device of this example operates like the device shown in Drawing 1, it is more preferred than the device shown with an assembly being easy in Drawing 1 in respect of a dynamic range. Intermediary To have [ as ] which moves the distance in which object lens 28 is longer than object lens 2 of Drawing 1. account rho In this example, read-out is performed by the penetration of light and data is used as bottom 42 of substrate 4. Object lenses 28 and 27 have a common focal plane so that an optical beam may converge on point 22 geometrically. The position of point 22 on optic axis 11 is related to the position of object lens 28. Of course, the present invention is not limited only to the example described above, and the control convergence device of the present invention can be applied to arbitrary optical read-out of the information held by the track which moves. However, the device of the present invention fits especially read-out of high-density information like a television signal, and it can use it easily simultaneously also as a device which reads in relation to J track axis within a plane parallel to the physical substrate of a track, and performs transverse direction amendment of the position of a device. Although the present invention was explained in detail above, the modes of the main operations of the present invention are enumerated below. 1 A device whose above-mentioned pilot signal is a sine wave in a device given in a claim. The above-mentioned device [ signal / in the device of a statement, read a pilot signal to the scope of two applications for patent, and ], The envelope and pilot signal of the above-mentioned read-out signal are received, and it has a synchronous detection machine which gives the electric signal containing a direct-current ingredient, when convergence of the beam on a track is inaccurate, the above-mentioned electric signal constitutes the above-mentioned error signal, the amendment which should be performed turns to the above-mentioned error signal, and it is boiled, therefore it is a positive or negative device. 3 A device to which it comes to carry out movement of the above-mentioned object lens by the above-mentioned device which gives an error signal under an operation of the above-mentioned pilot signal in a device given in a claim. In the device of a statement, the scope of four applications for patent is further equipped with a threshold switch and the peak detector of the above-mentioned read-out signal, A device which is constituted and becomes so that the above-mentioned comparing device and the above-mentioned error signal impression device may be separated, when the above-mentioned peak detector is connected to the above-mentioned switch, the above-mentioned switch is formed between the above-mentioned comparing device and the device which gives the above-mentioned error signal, and the level of the above-mentioned read-out signal is lower than the above-mentioned threshold. 5 A device further provided with the source of variable direct-current voltage connected to the above-mentioned error signal impression device in a device given in mode 4. 6 A device with which it comes to carry out the above-mentioned read-out by making light penetrate in the inside of the above-mentioned substrate in a device given in a claim. 7 A device with which reflection of the optical beam from one field of the above-mentioned substrate comes to carry out the above-mentioned read-out in a device given in a claim. A device which has the same focal plane as the object lens which is further provided with the 2nd object lens, this 2nd object lens is the latter part of the above-mentioned object lens which moves, is fixed to the position within the orbit of the above-mentioned optical beam, and moves in a device given in 8 and a claim.

[Brief Description of the Drawings]

An explanatory view for the schematic illustration and Drawing 2 in which Drawing 1 shows one example of the device of the present invention to illustrate operation of the device of the present invention, and Drawing 3rd [ the ] and 4 are another operation Show schematic illustrations of the device of the present invention. 2, 27, 28 ... An object lens, 3 ... An optical power detector, 4 .. A board, 5 ... amplifier, 6 ... envelope detection machine, 7 ... synchronous detection machine, 8 -.. peak detector, 10 -.. low-pass filter, 20 ... phase converter, 21 ... lens Retraction attachment instrument, 30 .. A spirit generator, 40 ... source of variable direct-current voltage, 50 ... adding machine, 60 ... motor.