CN1851814A - Optical disk vertical deviation detecting method - Google Patents
Optical disk vertical deviation detecting method Download PDFInfo
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- CN1851814A CN1851814A CN 200610035474 CN200610035474A CN1851814A CN 1851814 A CN1851814 A CN 1851814A CN 200610035474 CN200610035474 CN 200610035474 CN 200610035474 A CN200610035474 A CN 200610035474A CN 1851814 A CN1851814 A CN 1851814A
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Abstract
This invention puts forward a method for testing CD vertical deviation characterizing that it gets the optical disk surface vertical deviation and the wrap parameter based on testing torquer of an optical head, in which, it utilizes a Doppler laser vibration meter to get amplitude-frequency characteristic of the torquer on the focusing direction then tests the relation of the drive voltage and the CD wrap on the focusing coil suitable for testing DVD/CD etc. disks.
Description
Technical field
The present invention proposes a kind of detection method of novel optical disc vertical missing, especially be adapted to the detection of all kinds of discs such as DVD/CD and movement plane vertical missing and warpage, belong to the light storage device technical field of performance test.
Background technology
" CD-R (CD-R) conventional sense parameter " (CY/T 38-2001) ratified, announced by General Administration of Press and Publication of the People's Republic of China August calendar year 2001, and come into effect in January, 2002.Vertical missing DEV (Deviation) is a very important index that is used for weighing CD quality.It is defined as the maximum normal distance on beam reflection identity distance designated reference plane, and unit is mm.The allowed band of standard code vertical missing be DEV＜± 0.5mm.The measurement result of vertical missing except the influence that is subjected to factors such as disc thickness tolerance, refractive index, is subjected to the influence of disc warpage more.Therefore, be the normalized optical head at optical head, promptly under the situation without any vertical missing, vertical missing and disc warpage have certain relevance, generally can measure one of them amount and by calculating another amount.
When optical head read information in driver, focus servo mechanism moved up and down optical head, kept focal beam spot all the time on the optical disc information face.The tracking power of focus servo mechanism and frequency response have certain scope, if disc warpage is too big, hot spot can't focus on the information track, causes the focus tracking problem.General alleged warpage is meant " axially warpage " (Radial Tilt) mostly, and " tangential warpage " (Tangential Tilt) also arranged.
The measurement of traditional disc warpage is to obtain the reflection ray of incident laser at flat disc base and warpage dish base by use photodetection array, and the difference of calculating two reflection angles then obtains angularity (Tilt Angle) and vertical missing DEV.Because the precision of this detection method depends on the stability of light path and the sensitivity of sensor to a great extent, therefore strengthened the cost of test to a great extent.
Patent content
The objective of the invention is to propose a kind of detection method of optical disk vertical deviation, reduce testing cost.
A further object of the present invention is according to measured numerical value to optical disk vertical deviation, further obtains angularity numerical value, perhaps the vertical missing numerical value of optical head movement.
The present invention realizes that the detection method of the optical disk vertical deviation of above-mentioned purpose comprises the steps: A, allows optical head CD be done the operation that reads or writes totally, write down the variation of torquer coil voltage in this process, obtain voltage max Vmax and voltage minimum Vmin; B, calculate the vertical missing of CD according to following formula: DEV=k (Vmax-Vmin), wherein, k is the dynamic sensitivity of pre-determined torquer focus direction, DEV is measured vertical missing.
Technical scheme of the present invention further comprises following feature:
Definite method of the dynamic sensitivity k of employed torquer focus direction comprises the steps: K1, adopts vialog to accurately measure the displacement of focus direction of optical head moment apparatus and the relation between the input voltage among the described step B, obtains the displacement amplitude-frequency relation of torquer; K2, choose the pairing frequency of dynamic sensitivity,, can obtain the pairing yield value Value of this frequency according to determined amplitude-frequency relation in the step K 1, according to the relation of yield value Value and sensitivity, get final product the size of dynamic sensitivity k of focus direction.
Vialog in the described step K 1 is the laser doppler vialog; Displacement amplitude-frequency relation adopts the mode of displacement amplitude-frequency graph of a relation to represent in the described step K 1; In the described step K 2, the pass of yield value Value and sensitivity is: 201gk=Value, and wherein the unit of yield value Value is a decibel, the unit of dynamic sensitivity numerical value k is μ m/v.
The pairing frequency selection purposes of dynamic sensitivity is 200Hz ± 20Hz, that is: described dynamic sensitivity measures when torquer is in the intermediate frequency duty.
Described torquer is a normalized optical torquer.
In the described steps A, when doing the operation that reads or writes totally to CD, optical head keeps focusing on closed loop, tracking open loop.
In the described steps A, the method that writes down the variation of torquer coil voltage in this process is by oscillograph recording.
In the described steps A, when optical head is done the operation that reads or writes totally to CD, be to drive the most inboard outermost of reading CD of optical head from CD by the optical head sliding motor.
According to measured vertical missing, can further obtain the value of the vertical missing of the value of angularity of CD or optical head movement:
When described torquer is normalized optical torquer, then can calculate the angularity of CD: tg=k ' DEV/ (R1-R0) according to the following relation of vertical missing of being tested and angularity, wherein, it is angularity, unit is °, and R1 is a data of optical disk district maximum radius, and R0 is a data of optical disk district least radius, k ' is the unit conversion coefficient, and the unit that is used for DEV and R1, R0 are adopted adjusts consistent.
When described CD was standard optical disc, then the vertical missing of measured CD was the vertical missing of optical head movement.
The invention has the beneficial effects as follows: since this novelty that the present invention proposes obtain the method for CD quality parameter based on optical head moment apparatus focusing coil voltage detecting, made full use of the high precision that optical head moment apparatus had, characteristics such as micrometric displacement and sensitivity height detect the vertical missing and the small warpage of CD.Utilize the dynamic perfromance of optical head moment apparatus, mainly be that its dynamic sensitivity is set up the relation between vertical missing and the voltage signal, in monitoring torquer coil voltage, promptly can obtain the important quality parameter of CD: vertical missing and angularity also can obtain the vertical missing of optical head movement.Compare with conventional disc warpage detection method, convenient and easy when not reducing measuring accuracy, greatly reduced testing cost.
Description of drawings
Fig. 1 is a kind of torquer amplitude versus frequency characte test synoptic diagram of the embodiment of the invention.
Fig. 2 is the basic structure synoptic diagram of used a kind of optical head moment apparatus in the embodiment of the invention.
Fig. 3 by in the embodiment of the invention the amplitude-frequency phase-frequency characteristic curve map of a kind of torquer of obtaining of test.
Fig. 4 is embodiment of the invention optical disk vertical deviation and warpage pick-up unit synoptic diagram.
Fig. 5 is embodiment of the invention optical disk vertical deviation and warpage testing process synoptic diagram.
Wherein, 1 is the laser doppler vialog, and 2 is torquer, 3 is dynamic signal analyzer, and 4 is power amplifier, and 201 is holder, 202 is suspension wire, and 203 is objective carrier, and 204 is object lens, 205 is the tracking coil, and 206 is coil, and 207 is magnet, 208 is yoke, and 5 is CD, and 501 is disc tracks, 6 is spindle motor, and 7 is sliding motor, and 8 is the rack-and-pinion engaging piece.
Embodiment
The testing process of present embodiment relates generally to two parts: first utilizes the laser doppler vialog to obtain optical head moment apparatus amplitude versus frequency characte on focus direction; Second portion is the driving voltage on the torquer focusing coil and the detection of disc tilt relation.Wherein first prepares for second portion, if optical head moment apparatus amplitude versus frequency characte on focus direction has been arranged in advance, then can omit this step.
In first, at first adopt the laser doppler vialog to accurately measure the displacement of optical head moment apparatus and the relation between the input voltage, testing apparatus is as shown in Figure 1.Wherein involved key instrument has: laser vibration measurer, signal generator, oscillograph, D.C. regulated power supply, HP35670A dynamic signal analyzer or the like.
Its concrete testing process is: by the sinusoidal signal of signal generator output single-frequency, measure the response of torquer in focus direction and tracking direction respectively.At this moment, torquer all is presented as the vibration that frequency is single in the motion of focusing and tracking direction.The laser doppler vialog records after this vibratory response, and the result exports oscillograph to gained.Then make the HP35670A dynamic signal analyzer be in the state of automatic frequency sweep, the laser doppler vialog records the torquer vibration at each frequency sweep frequency place in the passband, export this signal to the HP35670A dynamic signal analyzer, carry out amplitude and bit comparison mutually with original swept-frequency signal, export final amplitude-frequency phase frequency curve figure and (focus on and tracking test respectively; The just amplitude frequency curve figure of focus direction that wants required for the present invention).On the amplitude-frequency phase frequency curve, get the pairing point of each frequency in the amplitude frequency curve, obtain corresponding yield value Value (dB), by 201g (sensitivity k)=Value, get final product the size of different frequency bottom offset sensitivity.Getting frequency is 200Hz, can obtain dynamic sensitivity numerical value k (unit: μ m/v).
Torquer wherein is exactly the torquer that we are used for optical head at ordinary times.In optical disk system, optical head is complicated accurate ray machine electricity integrated system, and its function is accurately to read and export the numerical information that is stored in the CD.Optical head mainly is made up of semiconductor laser, object lens, torquer and four primary clusterings of PDIC.Wherein, torquer is a core component.When data cd is in the duty of high speed rotating, because the existence of various errors, manufacture craft or main shaft and problems such as the axis hole of disc cooperates as CD, disc always can produce certain dipping and heaving, inclination and course deviation, thereby causes always reading of information track can produce certain deviation.This deviation is for data-signal, and is fatal often, and it can cause the bit error rate to improve, even optical head is quit work.Therefore, reliability in order to ensure optical head work, and can correctly read information on the CD, optical head must accurately be adjusted the deviation between self and the disc in real time, to guarantee that focal beam spot always accurately drops on to bias free on the information track of CD.The function that this oneself of optical head adjusts is finished by torquer.The effect of torquer just is to read the error signal of obtaining in the process according to optical head at CD, promptly focusing and tracking error signal are (for the HD-DVD system, also there is tilt error signal etc.), drive the object lens motion in real time, the hot spot that the fluctuating vibration that makes focal beam spot can overcome CD brings is in the skew of disc focus direction and trajectory direction, thereby accurately drop on the information track of CD, realize high-quality reading and writing data.Wherein, focus movement can be so that object lens move on perpendicular to the direction of optical disc information face, to guarantee that focal beam spot accurately drops on the information sides of disc; The tracking motion then is that the control object lens move on the direction that is parallel to the optical disc information face, to guarantee that focal beam spot accurately drops on the information track of disc.Have only focal beam spot can accurately drop on the information track of disc, could guarantee accurately reading of data of optical disk.
According to textural difference, torquer can be divided into two classes, i.e. elastic bearing type and slide rotary-type (what provide as Fig. 2 is 4 suspension wire formulas, and it belongs to the resiliency supported type).Wherein, elastic bearing type torquer can also be divided into cantilevered, suspension wire formula, elasticity chip etc. according to the difference of supporting form; The rotary-type torquer that slides is called for short the type that trackslips, and structurally then only has fixed shaft type a kind of.
Torquer mainly is made up of fixed part, movable member.In elastic bearing type torquer, movable member mainly is made up of object lens and support thereof, focusing coil, tracking coil etc., and fixed part is made up of base, interior yoke, outer yoke, focus magnet, tracking magnet etc.Connection between fixed part and the movable member relies on high performance elastic bearing to realize that these elastic bearings are keys of the type torquer, and their performance has determined the serviceability of torquer.
The drive principle of torquer is: optical head by focusing and the tracking error signal that PDIC obtained, focuses on and the tracking electric current through obtaining after the processing of servo circuit in the process of reading of data.These two kinds of electric currents are sent to respectively in the focusing and tracking coil that is fixed on the movable member.Under the combined action of these current-carrying coils each permanent magnet field in fixed part, be subjected to certain magnetic field force.The movable member of torquer focuses on accordingly with tracking and moves under the effect of magnetic field force.In this process, the elastic parts in the torquer is as spring suspension, spring iron plate or suspension iron core, for movable member provides certain motional feedback power.Wherein, focusing coil mainly provides the driving force on the focus direction.
About further specifying of torquer, please refer to the article " dvd pickup head torquer Review Study " (first phase trial issue in 2006 of " recording medium technology " magazine hardware) of Zhang Buqing etc.
Be a displacement amplitude-frequency phase frequency curve figure as shown in Figure 3 by the torquer of device acquisition shown in Figure 1.Wherein, the Gain of the longitudinal axis represents yield value, and unit is dB, and the Phase of the longitudinal axis represents phase place, and unit is deg, i.e. ° (degree), the Frequency of transverse axis represents frequency, unit is Hz.Notice that though shown in Fig. 3 be a figure who comprises phase frequency curve, wherein phase frequency curve is not that this method is needed, just the processing power of this instrument comprises this content, and is therefore shown in Figure 3.
On focus direction, after the amplitude versus frequency characte, can enter the key component of this method, i.e. second portion obtaining optical head moment apparatus.The driving voltage on the torquer focusing coil of second portion and the pick-up unit of disc tilt relation are as shown in Figure 4.
Detailed process is as follows: under the prerequisite that focuses on closed loop, tracking open loop, allow normalized optical sliding motor drive an optical head and do overall detection, observe and write down torquer coil voltage change curve in this process by oscillograph from the most inboard outermost of reading CD of CD.It is Vmax that maximal value is pressed in power taking, and getting minimum value is Vmin, and unit is V (volt), and then the vertical missing of CD is
DEV＝k(Vmax-Vmin) (1)
Then have:
In the following formula, k is that (unit: μ m/V), DEV is a vertical missing (unit: μ m) for the sensitivity of torquer focus direction.Be angularity (unit: °), R1 is a data of optical disk district maximum radius, and R0 is data of optical disk district least radius (mm of unit).R1, R0 are different with the difference of disk types, and for DVD-R, R1=58mm, R0=24mm. just can obtain the angularity of CD thus.
Wherein multiply by coefficient 0.001 is for consistent with the coefficient adjustment of R1, R0 DEV.For being without loss of generality, can use coefficient k with 0.001 ' expression, when DEV with R1, when R0 is consistent, k '=1, and in this example, owing to the unit of DEV is μ m, the unit of R1, R0 is mm, so k '=0.001.
Fig. 5 carries out general steps synoptic diagram after comprehensive to above-mentioned first and second portion.
In the superincumbent testing process, used optical head is the normalized optical head, and it self does not have vertical missing, therefore can be used for calculating the disc tilt degree.Conversely, be standard optical disc if get described CD, CD self is without any warpage, and then the vertical missing of measured CD is the vertical missing of optical head movement.
The method that the present invention proposes based on optical head moment apparatus focusing coil voltage detecting, changed traditional detection method that depends on light path and photo detector array, have highly sensitive, test characteristics such as simple, the plane warping that is widely used in CD, DVD and other all kinds of CDs and movement detects.
The foregoing description only is that the present invention will be described for clearer, and can not be interpreted as limiting the scope of the invention.Those skilled in the art may make some flexible embodiments by reading the present invention; equally also belong to protection scope of the present invention; for example: when optical head is done the operation that reads or writes totally to CD, keep focusing on closed loop, tracking open loop; but also can allow the tracking closed loop; do not influence measurement result (this be because; coil and tracking coil separate, and the two voltage can superposition).For another example, dynamic sensitivity numerical value k institute respective frequencies is 200Hz among the embodiment, but is not strictly limited to this value.Generally speaking, dynamic sensitivity measures when torquer is in the intermediate frequency duty, dynamic sensitivity has reflected torquer in serviceability, and it can be obtained by slope of a curve between movable member moving displacement and the intermediate frequency drive current (or driving voltage).
Claims (10)
1. the detection method of an optical disk vertical deviation is characterized in that this method may further comprise the steps:
A, allow optical head that CD is done the operation that reads or writes totally, write down the variation of torquer focusing coil voltage in this process, obtain voltage max V max and voltage minimum V min;
B, calculate the vertical missing of CD according to following formula:
DEV=k (V max-V min), wherein,
K is the dynamic sensitivity of pre-determined torquer focus direction, and DEV is measured vertical missing.
2. the detection method of optical disk vertical deviation according to claim 1 is characterized in that definite method of the dynamic sensitivity k of employed torquer focus direction among the described step B comprises the steps:
K1, adopt vialog to accurately measure the displacement of focus direction of optical head moment apparatus and the relation between the input voltage, obtain the displacement amplitude-frequency relation of torquer;
K2, choose the pairing frequency of dynamic sensitivity,, can obtain the pairing yield value Value of this frequency according to determined amplitude-frequency relation in the step K 1, according to the relation of yield value Value and sensitivity, get final product the size of dynamic sensitivity k of focus direction.
3, the detection method of optical disk vertical deviation according to claim 2 is characterized in that:
Vialog in the described step K 1 is the laser doppler vialog;
Displacement amplitude-frequency relation adopts the mode of displacement amplitude-frequency graph of a relation to represent in the described step K 1;
In the described step K 2, the pass of yield value Value and sensitivity is:
20lgk＝Value，
Wherein the unit of yield value Value is a decibel, dynamic sensitivity numerical value k's
Unit is μ m/v.
4, according to the detection method of claim 2 or 3 described optical disk vertical deviations, it is characterized in that: the pairing frequency selection purposes of dynamic sensitivity is 200Hz ± 20Hz, that is: described dynamic sensitivity measures when torquer is in the intermediate frequency duty.
5, the detection method of optical disk vertical deviation according to claim 1 is characterized in that: in the described steps A, keep focusing on closed loop, tracking open loop when optical head is done the operation that reads or writes totally to CD.
6, the detection method of optical disk vertical deviation according to claim 1 is characterized in that: in the described steps A, the method that writes down the variation of torquer coil voltage in this process is by oscillograph recording.
7, the detection method of optical disk vertical deviation according to claim 1, it is characterized in that: in the described steps A, when optical head is done the operation that reads or writes totally to CD, be to drive the most inboard outermost of reading CD of optical head from CD by the optical head sliding motor.
8, the detection method of optical disk vertical deviation according to claim 1, it is characterized in that described torquer is a normalized optical torquer, described method further comprises the steps: to calculate according to the following relation of vertical missing of being tested and angularity the angularity of CD:
tgα＝k’·DEV/(R1-R0)
Wherein, α is an angularity, and unit is °, and R1 is a data of optical disk district maximum radius, and R0 is a data of optical disk district least radius, and k ' is the unit conversion coefficient, and the unit that is used for DEV and R1, R0 are adopted adjusts consistent.
The detection method of 9 optical disk vertical deviations according to claim 1 is characterized in that: getting described CD is standard optical disc, and then measured vertical missing is the vertical missing of movement.
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| CN102201247A (en) * | 2010-03-24 | 2011-09-28 | 鸿富锦精密工业（深圳）有限公司 | Method and device for identifying warping of compact disc |
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| TWI222628B (en) * | 2003-07-09 | 2004-10-21 | Mediatek Inc | Method of vertical deviation disc detection |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102201247A (en) * | 2010-03-24 | 2011-09-28 | 鸿富锦精密工业（深圳）有限公司 | Method and device for identifying warping of compact disc |
| CN102201247B (en) * | 2010-03-24 | 2015-04-01 | 无为县特种电缆产业技术研究院 | Method and device for identifying warping of compact disc |
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