CN1315724A - Method and device for detecting tracking error of near-field optical R/W system - Google Patents
Method and device for detecting tracking error of near-field optical R/W system Download PDFInfo
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- CN1315724A CN1315724A CN 00103540 CN00103540A CN1315724A CN 1315724 A CN1315724 A CN 1315724A CN 00103540 CN00103540 CN 00103540 CN 00103540 A CN00103540 A CN 00103540A CN 1315724 A CN1315724 A CN 1315724A
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Abstract
A method and its device for detecting the tracking error of near-field optical R/W system are disclosed. The track grooves are arranged on the non-storage surface of optical record medium and two signal pick-up light points are used. At the first light point, the data is stored on the optical record medium. The second light point focused at track groove is used to detect the track error signal (TES) by push-pull tracking method for increasing the storage density of optical record medium in near-field optical R/W system.
Description
The invention relates to a kind of tracking error detecting method and device of near-field optical R/W system, particularly a kind of being applied in the near-field optical R/W system, can improve the data storage density of optical record medium, and can utilize plug-type tracing to detect the method and apparatus of tracking error.
The optical information read-write system is an important business to produce the very little luminous point of diameter, spot diameter is more little, it is big more that the money that stores on the optical record medium is read capacity, and wherein the numerical aperture of the lens of spot diameter and focused beam (Numerical Aperture NA) is inversely proportional to.
Known near-field optical R/W principle, please refer to Fig. 1, be to inject and to be limited in this plano-convex lens 12 by the lower surface of a plano-convex lens 12 by the convergent beam of a traditional type read/write head 11 outputs to propagate, then can on this plano-convex lens 12, cause very big NA value in the surface, also just obtain the very little luminous point of diameter (luminous point A), in optical term weighing-appliance have the lens of this kind function be solid-state filling lens (Solid Immersion Lens, SIL).Through suitably design, can get NA=n * sin θ '=n (n * sin θ)=n
2* sin θ, θ herein are the beam convergence angle by 11 outputs of traditional type read/write head.With a video disc 13 near this plano-convex lens 12, then because near field optical effects, the part light wave can pass the air-gap (the about 0.15 μ m of thickness) of 13 of plano-convex lens 12 and video discs and form luminous point (luminous point B) with the same diameter of luminous point A at lower surface 131 places of video disc 13, light is reflected by luminous point B, catoptrical physical property (intensity or polarization vector) is influenced by the stored data of this point, and reflected light is lighted by B, near field optical effects takes place once again and the reverse air-gap that passes, get back to this plano-convex lens 12 and this traditional type read/write head 11, this traditional type read/write head 11 detects the physical property of these light and can judge information on this video disc 13.
And used video disc 13 in the known near-field optical R/W system, as shown in Figure 2, be one have two smooth (trackless ditch) surface disk, wherein lower surface 131 is coated with the optical recording material film, and with this face near SIL12, allow this luminous point B drop on this film, 132 no special use of last one side.
The tracking error detecting method that is adopted in the known again near-field optical R/W system is servo (the Sample Servo of sampling, SS) method, its principle is: be divided into several virtual sectors (sector) in each virtual circle of track, at each sector section start tracking signal sampling at pre-quarter pitting 24, during running, the luminous point that the light beam line focus is produced is the function of the inclined to one side rail amount of luminous point falling within the intensity of reflected light that reflects again behind the tracking signal sampling pitting 14, detect the light echo of this reflection and can declare the inclined to one side rail margin of error of knowing luminous point, the inclined to one side rail error photocurrent that detects gained is sent into the read/write head servo control mechanism, can correct the inclined to one side rail of object lens.But, the SS method has two big shortcomings, first shortcoming is to cooperate running with high-revolving motor: suppose that inclined to one side rail behavior is that frequency with 2kHz constantly takes place, for can be with its timely correction, must manage to produce the inclined to one side rail error photo-signal waveform that frequency is 2kHz, therefore the frequency of occurrences of tracking signal sampling pitting 24 must be at least 4kHz, suppose to contain 50 sectors in track one circle, motor rotary speed is frps, then * and 50=4kHz, via calculating f=80rps=4800rpm, so high rotating speed requires and must be realized by high rotating speed motor, again because of high rotating speed motor is difficult for obtaining, so make the cost of near-field optical R/W head be difficult for reducing; Another shortcoming of SS method is: one fen space in order to store data has been occupied in the existence of tracking signal sampling pitting 24, thereby has reduced the total data storage amount on the video disc.
As known from the above, the shortcoming of known system is only to produce a luminous point, with a luminous point, should provide near field optical effects, detects tracking error signal again, the servo method of having to take to take a sample.If can create a kind of new system, make it produce two luminous points, be used separately as the data of reading and detect tracking error signal, then can avoid adopting and get the shortcoming that servo method causes.
In view of this, purpose of the present invention is for the known near-field optical R/W system of improvement, to improve the data storage density of the optical record medium in this near-field optical R/W system.
Another object of the present invention is applied in the near-field optical R/W system providing a kind of, and need not use high rotating speed motor to cooperate, easily detection obtain tracking error signal and device.
According to above-mentioned purpose, the present invention is provided with the rail ditch that can utilize plug-type tracing to obtain tracking error signal in the non-data storage surface of optical record medium, and utilize the means that can produce two picking up signal luminous points, first luminous point in order to reading/writing document is provided respectively in the near-field optical systems, and in order to obtain second luminous point of tracking error (TES) signal, thereby improve sampling servo (Sample Servo, SS) the method deficiency that pitting cooperates with high rotating speed motor of need taking a sample.Be to produce two picking up signal luminous points in the disclosed preferred embodiment of the present invention by the solid-state filling lens (SIL) with two kinds of surface curvatures.
The present invention more can increase the tracking lock route in same rail ditch, according to JapaneseJournal of Applied Physics, Vol.38 (1999), among the pp.1774-1776 gained and result of calculation learn: in the rail ditch at the most with three tracking lock routes of tolerable, and its below that increases route also can store data, and makes the data storage density of near-field optical R/W system of the present invention can increase to many three times thereupon.
For above-mentioned and other purposes of the present invention, feature and advantage can be become apparent, a preferred embodiment cited below particularly, and cooperate institute's accompanying drawing, be described in detail below.
Fig. 1 illustrates known near-field optical R/W system organigram;
Fig. 2 illustrates the organigram of used video disc in the known near-field optical R/W system;
Fig. 3 A illustrates the organigram of the major technique among the present invention;
Fig. 3 B can show the organigram of optical record medium first embodiment among the present invention;
Fig. 3 C illustrates the organigram of optical record medium second embodiment among the present invention;
Fig. 4 A illustrates reflected light and recommends style cell relation synoptic diagram;
Fig. 4 B illustrates and recommends 2 style districts and gauge partially from concerning synoptic diagram;
Fig. 4 C paint inclined to one side gauge from plug-type tracking error signal TES graph of a relation;
Fig. 5 illustrates the organigram of whole near-field optical R/W system;
Fig. 6 illustrates plug-type tracking error signal TES and reference voltage V
iGraph of a relation; And
Fig. 7 illustrates many tracking lock route synoptic diagram.
Please refer to Fig. 3 A, disclosed technology comprises in according to the present invention: the upper surface 361 (non-data storage surface) at optical record medium 36 is provided with a rail ditch 3611, utilize the means that can produce two picking up signal luminous points again, generation is in order to first luminous point of reading/writing document, and in order to obtain second luminous point of tracking error (TES) signal.And preferred embodiment is to produce two above-mentioned luminous points by solid-state filling lens (SIL) 35, the lower surface of solid-state filling lens (SIL) 35 (that is side of close LASER Light Source) has two kinds of surface curvatures, when output beam sees through this solid-state filling lens (SIL) 35, owing to the difference of surface curvature is converted into two luminous points, wherein first luminous point drops on the lower surface 362 (data storage surface) of this optical record medium 36, utilize the near field optic principle and reading/writing document, second luminous point then drops on this optical record medium 36 among the rail ditch 3611 on one side 361 (non-data storage surface), and cooperates plug-type tracing (Push-pulltracking method) and produce the tracking error signal (TES) that this second luminous point is provided.
Please refer to Fig. 3 B, on the upper surface 361 of this optical record medium 36, be precast with the rail ditch 3611 of continuous shape, or be illustrated in figure 3 as the rail ditch of concentric circles, and be coated with the metallic reflection film thereon, the ditch of this rail ditch 3611 apart from and ditch depth done to such an extent that suitably cooperate with the diameter of output beam wavelength and P point (second luminous point), and make from the P point reflection and contain two plug-type style district e and f the light beam that returns, shown in Fig. 4 A, the light intensity in these two style districts, I
eAnd I
f, the inclined to one side gauge of ordering along with P from and change, shown in Fig. 4 B.Make TES=I
e-I
f, when the P point is positioned at the track centre, TES=0, when the centre of P point offset track, TES＜0 or TES＞0 is shown in Fig. 4 C.
The structure of whole near-field optical R/W system please refer to Fig. 5 among the present invention, the output beam that one LASER Light Source 31 is sent, behind a collimating mirror 32, become directional light, shoot to solid-state filling lens (SIL) 35 via marching to object lens 34 convergent beams after an optical splitter 33 reflections again, wherein this object lens 34 and these solid-state filling lens (SIL) 35, wherein these object lens 34 are connected by a support 317 with these solid-state filling lens (SIL) 35 and form a focusing unit 345.As previously mentioned, be divided into two different districts of surface curvature at the lower surface of this SIL35, the diameter range in first district is 0 to a, and its surface curvature radius is infinitely great, and the diameter range in second district is a to b, a＜b wherein, and its surface curvature radius is a finite value.The light beam that shoots to first district by its surface action after, in the space, form a luminous point P (aforesaid second luminous point) by these solid-state filling lens (SIL) 35, the light beam that shoots to second district by its surface action after, form a luminous point Q (aforesaid first luminous point) by this SIL35 and at the upper surface of this SIL35.With a thickness is that t, refractive index are the more top that the optical record medium 36 of n places these solid-state filling lens (SIL) 35 upper surfaces, also get suitable numerical value t and n, make that surface 361 is harmonious with the P point on this optical record medium 36, and the lower surface 362 of this optical record medium 36 again with the Q point very near causing near field optical effects to take place, and make a luminous point R appear on the lower surface 362.
From P point and R point reflection and the backhaul light beam that returns, by this optical record medium 36, behind these solid-state filling lens (SIL) 35 and these object lens 34, to be somebody's turn to do with this output beam of backhaul light beam by optical splitter 33 and to be separated to different light paths respectively, this backhaul light beam continues to hollow out shape optical splitter 37 by central authorities then, make the tracking signal of returning be separated into different tracking light beams and data light beam with the data signal that returns by the R point reflection by the P point reflection, wherein this tracking light beam is met a catoptron 37 and reflection and by a condenser 39, can be taken as one at last and reclaim luminous point and drop on sensitization 310.The sensitive surface of this sensitization 310 is divided into two photosensitive area E and F, is respectively V by these two photovoltages that photosensitive area produced
EAnd V
F, V wherein
EWith I
eBe directly proportional, V
FWith I
fBe directly proportional, with V
EAnd V
FSend into computing in the subtracter 311, get a plug-type tracking error signal TES=V
E-V
F=I
e-I
f, TES has a minimum voltage value V
MinWith a maximum voltage value V
Max, this TES signal is sent among the tracking servo circuit unit 312, be preset with a plurality of reference voltage V in it
i(i=1,2,3), V
Min＜V
i＜V
Max, it concerns that as shown in Figure 6 this tracking servo circuit unit 312 is with TES and V
iCompare, produce one according to result relatively and correct voltage V
d
If TES＞V
i, then this tracking servo circuit unit 312 can produce one on the occasion of correction voltage (V
d＞0), this voltage can be sent to one and follow the tracks of actuator 315, moves to the certain level direction to drive this focusing unit 345.These object lens 34 will cause the change of the inclined to one side rail state of P point, to such an extent as to TES value and V after moving with these solid-state filling lens (SIL) 35
dValue also changes thereupon, and this program repetitiousness is always carried out up to TES=V
iThe time till.If it is enough sensitive to follow the tracks of the effect of actuator 315, then TES almost is constantly equal to V
i, then visual TES is constantly equal to a positive constant or zero, so the P point is maintained at the offset track centre or just be on the interior a certain virtual route of track, that is the P point is locked on a certain route.
If TES＜V
i, then this tracking servo circuit unit 312 can produce the correction voltage (V of a negative value
d＜0), this voltage can be sent to this tracking actuator 315 equally, so that this focusing unit 345 moves to another horizontal direction.These object lens 34 will cause the change of the inclined to one side rail state of P point, to such an extent as to TES value and V after moving with these solid-state filling lens (SIL) 35
dValue also changes thereupon, and this program repetitiousness is always carried out up to TES=V
iThe time till.If it is enough sensitive to follow the tracks of the effect of actuator 315, then TES almost is constantly equal to V
i, then visual TES is constantly equal to a negative value constant or zero, so P point is maintained at the offset track centre or just be on another interior virtual route of track, that is the P point is locked on another route.
Program discussed above is called " tracking lock ", V
iBe called tracking lock voltage, a V
iThe corresponding trace of value, this route needn't be in the centre of track, because V
iThe tracking lock route can be multiple value, so though track has only one, can be many, as shown in Figure 7, there is the read-write luminous point R (or Q point) of a correspondence below of each bar route, can implement the effect of " reading ", " writing " or " wiping ", V to optical record medium 36
iFor few more than the number, i.e. the maximal value of i depends on the merchant of R point (or the Q point) spot diameter of locating and the gained that is divided by of gauge.
The following table 362 of the applied optical record medium 36 of the present invention (data storage surface) is complete smooth plane, is coated with the film of optical recording material on it.Tracking error detecting method of the present invention can be applicable to multi-form optical record medium 36, as " read-only type ", " dyestuff formula Write-only one time type ", " phase-change type Write-only one time type ", " the erasable repeatedly type of phase-change type " and " the erasable repeatedly type of magneto-optic formula " etc., all can utilize said method locking tracking route, enumerate " the erasable repeatedly type of phase-change type " now and illustrate that it " is read ", the principle of work of " writing " and " wiping ".
Please referring again to Fig. 5, write fashionable, the data signal string is transported to the driving circuit 314 of LASER Light Source 31, making this electricity penetrate light source 31 produces and data " 1 ", " high-strength " of " 0 " correspondence, the output beam of " in strong " intensity alternate, this output beam as previously mentioned, passing through this collimating mirror 32, this optical splitter 33, behind these object lens 34 and these solid-state filling lens (SIL) 35 elements such as grade, be coated with at optical record medium 36 via near field optical effects and form luminous point R on the lower surface 362 of optical recording material, variation along with LASER Light Source 31 output light intensities, corresponding variation also takes place in the light intensity at R point place: when the R point receives the light beam of " high-strength ", the optical recording material generation physical change of this point and become noncrystalline attitude, this has promptly write data " 1 " at this point; When the R point receives the light beam of " in strong ", the optical recording material generation physical change of this point and become crystalline state, this has promptly write data " 0 " at this point.
When reading, make LASER Light Source 31 send the light beam of constant " low strong " luminosity, this light as previously mentioned, to pass through this collimating mirror 32, this optical splitter 33, behind these object lens 34 and these solid-state filling lens (SIL) 35 elements such as grade, form luminous point R with the lower surface 362 of data via near field optical effects at optical record medium 36, the backhaul light beam that returns from the R point reflection, it is stronger that chance " crystalline state " is located intensity of reflected light, meet " noncrystalline attitude " locate intensity of reflected light a little less than, this light beam via near field optical effects by the Q point, again by solid-state filling lens (SIL), object lens 34, optical splitter 33, meet central authorities then and hollow out shape optical splitter 37, the reflection back can be taken as a recovery luminous point and drop on sensitization 313 by condenser 316, produce photovoltage V at this sensitization 313
R, V
RBe directly proportional with catoptrical intensity, detect V
RSize, know that promptly reflected light is to locate from " crystalline state " or " noncrystalline attitude ", know that promptly data is 0 or 1, so V
RPromptly be that data reads signal RFS.
When wiping, make LASER Light Source 31 send the light beam of constant " in strong " luminosity, as previously mentioned, this light beam is by this collimating mirror 32, this optical splitter 33, behind these object lens 34 and these solid-state filling lens (SIL) 35 elements such as grade, on the lower surface 362 of data, form luminous point R via near field optical effects at this optical record medium 36, since the irradiation R light beam of order be all " in by force; luminosity; make that this optical recording material generation physical change is a crystalline state; that is all write data " 0 " on this optical record medium is equal to the original data of this optical record medium is all wiped.
Though the present invention discloses as above with a preferred embodiment; right its is not in order to qualification the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; all can do to change and distortion, so protection scope of the present invention only is limited by the accompanying claims.
The present invention utilize to produce the means of two picking up signal luminous points and respectively to optical record medium access data and tracking lock, so can utilize plug-type tracing (push-pull trackingmethod) to detect tracking error signal (TES), thereby servo (the Sample Servo of improvement sampling, SS) need take a sample pitting and the problem that high rotating speed motor cooperates of method makes the data storage amount of optical record medium strengthen and can reduce departmental cost.
In addition, the present invention more can increase the tracking lock route in same rail ditch, and makes data storage density significantly increase thereupon.
Claims (17)
1, a kind of tracking error detecting method of near-field optical R/W system can make the data density of optical record medium in this system significantly promote, and cooperation that need high rotating speed motor, and this method includes at least:
On the non-data storage surface of this optical record medium, the rail ditch is set;
One means that can produce two picking up signal luminous points are provided, produce first luminous point in order to reading/writing document in order to data storage surface at this optical record medium, and second luminous point that focuses on this rail ditch place; And
Utilize plug-type tracing and obtain by this second light point reflection and the tracking error signal (TES) of the tracking light beam representative that returns.
2, the tracking error detecting method of near-field optical R/W system as claimed in claim 1, wherein this rail ditch is continuous shape or concentric circles, and scribbles reflective film thereon.
3, the tracking error detecting method of near-field optical R/W system according to claim 1, wherein this can produce the means of two picking up signal luminous points, be to be divided into two different districts of surface curvature by one side with the close LASER Light Source of lens, make see through these lens by the emitted output beam of this LASER Light Source after, on this optical record medium, form these two picking up signal luminous points.
4, as the tracking error detecting method of the near-field optical R/W system as described in the claim 3, wherein these lens are solid-state filling lens (SIL).
5, the tracking error detecting method of near-field optical R/W system as claimed in claim 3 wherein further utilizes a collimating mirror, and this output beam is treated to parallel beam.
6, the tracking error detecting method of near-field optical R/W system as claimed in claim 3 wherein further utilizes object lens, in order to this output beam effect is become convergent beam and shoots to this lens.
7, the tracking error detecting method of near-field optical R/W system as claimed in claim 1, wherein this plug-type tracing further includes the path of separating light beam, utilize an optical splitter, in order to the loop that this output beam is returned with reflecting from this optical record medium.
8, the tracking error detecting method of near-field optical R/W system as claimed in claim 1, wherein this plug-type tracing further includes, the path of separating light beam, utilize central authorities to hollow out the shape optical splitter, a tracking light beam that returns with this second light point reflection in order to the data light beam that this first light point reflection is returned is separated to different light paths.
9, the tracking error detecting method of near-field optical R/W system as claimed in claim 8 wherein further utilizes a catoptron, changes the direct of travel of this tracking light beam or this data light beam.
10, the tracking error detecting method of near-field optical R/W system as claimed in claim 8, wherein this tracking light beam drops on sensitization that a sensitive surface is divided into two photosensitive areas, and by the indivedual photovoltages that produce of these two photosensitive areas, and these two photovoltages are sent into computing in the subtracter, and obtain this tracking error signal (TES).
11, the tracking error detecting method of near-field optical R/W system as claimed in claim 10, the wherein generation of this tracking error signal (TES), further utilize a condenser, being disposed at these central authorities hollows out on the light path between shape optical splitter and this sensitization, in order to assemble this tracking light beam on this sensitization.
12, a kind of tracking error detecting device of near-field optical R/W system, the output beam that a LASER Light Source is produced wherein, shine the optical record medium of rail ditch and reflect a backhaul light beam, and utilize plug-type tracing (Push-pull tracking method) and detection tracking (Tracking) error, it includes at least:
One changes ditch, and it is located on the non-data storage surface of optical record medium;
One optical splitter is disposed on the optical path of this optical R/W system, this output beam can be separated to different light paths respectively with this backhaul light beam;
One focusing unit; Comprise object lens and solid-state filling lens (SIL); Be disposed at the optical path of this optical R/W system; Wherein these object lens become this output beam effect convergent beam and shoot to this solid-state filling lens; These solid-state filling lens are divided into two different districts of curvature near an end of these object lens; Therefore this convergent beam is through forming two luminous points behind these solid-state filling lens; Drop on respectively the data storage surface and this rail ditch place of this optical record medium; First luminous point wherein is in order to reading/writing document; And while second luminous point is in order to provide tracking error signal
One central authorities hollow out the shape optical splitter, are disposed at the optical path of this optical R/W system, and these two luminous points from the backhaul light beam that this optical record medium reflects, are separated into a different tracking light beam and data light beams;
One sensitization is disposed on the optical path of this tracking light beam, and its sensitive surface is divided into two photosensitive areas, should follow the tracks of the photovoltage of light beam in order to sensing; And
One subtracter carries out computing to these two formed photovoltages of photosensitive area, gets a plug-type tracking error signal (TES).
13, the tracking error detecting device of near-field optical R/W system as claimed in claim 12 wherein further includes a collimating mirror that is disposed at this optical R/W system light path, in order to the output beam that this LASER Light Source produced is treated to parallel beam.
14, the tracking error detecting device of near-field optical R/W system as claimed in claim 12 wherein further includes a catoptron that is disposed at this backhaul light path, in order to change the direct of travel of this tracking light beam or this data light beam.
15, the tracking error detecting device of near-field optical R/W system as claimed in claim 12 wherein further includes a condenser, is disposed at these central authorities and hollows out on the light path between shape optical splitter and this sensitization, in order to assemble this tracking light beam on this sensitization.
16, the tracking error detecting device of near-field optical R/W system as claimed in claim 12, wherein this rail ditch is to be continuous shape or concentric circles, and scribbles reflectance coating on this rail ditch surface.
17, the tracking error detecting device of near-field optical R/W system as claimed in claim 12, wherein this first luminous point is to utilize near field optical effects and drop on the face that this optical record medium has optical recording material, utilizes near field optical effects simultaneously and reaches the function of data reading-writing.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB001035401A CN1133980C (en) | 2000-03-24 | 2000-03-24 | Method and device for detecting tracking error of near-field optical R/W system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB001035401A CN1133980C (en) | 2000-03-24 | 2000-03-24 | Method and device for detecting tracking error of near-field optical R/W system |
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Granted publication date: 20040107 Termination date: 20120324 |