CN1240291A - Optical read/write device for data storage medium - Google Patents
Optical read/write device for data storage medium Download PDFInfo
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- CN1240291A CN1240291A CN 98115719 CN98115719A CN1240291A CN 1240291 A CN1240291 A CN 1240291A CN 98115719 CN98115719 CN 98115719 CN 98115719 A CN98115719 A CN 98115719A CN 1240291 A CN1240291 A CN 1240291A
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Abstract
The optical reading-writing equipment includes laser diode light-emitting unit, optical detection unit and optical system. Among them the laser diode and photodetector are made up by using the structure of vertical-cavity surface light-emitting laser. It also includes double-focus lens for guiding the light produced by light-emitting unit to the data storage medium, and guiding the light produced by said data storage medium to the optical detection unit. Said invention adopts the double-focus tens to separate the incident light from reflecting light, collect the incident light on CD disk, and make the reflecting tight project to the photodetector near the surface laser, so that it can save two spectroscopes and other mirror, can effectively eliminate optical feedback, can raise the resolution for reading optical disk and support miniaturization of laser head.
Description
The present invention relates to the optical playback technology, be specifically related to a kind of light that adopts semiconductor laser light source and reproduce the improvement of pick-up head aspect small-sized, more specifically say, relate to a kind of optical read-write device that adopts the data storage medium of bifocal camera lens.
CD has multiple, as video disc (LD), common CD CD, and VCD, CD-ROM etc.CD can write down simulating signal (FM FM signal) and digitally encoded signal, but the form of expression information all is similar on CD.Promptly represent with a hole groove that encloses of helical pattern on the CD.The pulse signal that laser head is read is corresponding with the hole groove on the CD, for digital signal, the pulse of laser head output is equivalent to " 0 " or " 1 " of binary digital signal, for simulating signal, the pulse signal frequency component wherein of laser head output is corresponding with video frequency modulation (FM) signal and sound accompaniment frequency modulation (FM) signal, promptly comprises the component of video and audio FM in the pulse signal.As long as when playing different CDs, impose corresponding demodulation or decoding processing method just can come out the information regeneration on the CD.Optical playback (reproduction) pick-up head commonly used adopts a photo-emission source and one or more receiver, is stored in the data message of surperficial medium in order to deciphering.Transmitter and receiver discrete component can be combined on the substrate, and what also have is encapsulated on the different discrete components, comes beam split by prism.When reading optical disc information with Ji Guang Head, (a series of Guang Learn of beam splitter), Tou Over element shines on the CD card semiconductor laser diode emitted laser bundle through grating.The laser of CD reflection passes through above-mentioned Guang Learn element Zhao She again Dao Inspection Measuring device.
Reading of optical disc information adopted three light beam modes more in video disc player, and so-called three light beams make the laser diode issued light become three beams of laser exactly and project on the CD.In the laser head the inside grating lens is housed, behind laser diode issued light bundle process grating, has just formed three light beams, there have a stronger main beam to be positioned in these three light beams to be middle, and two equal auxiliary beams are positioned at both sides.Main beam is mapped on the information line of CD and is used to read information.Two auxiliary beams also are mapped on the same information line, just one before main beam, one after main beam.These two auxiliary beams are used to detect tracking error, realize automatic trace information line by tracking servo.
Existing optical pickup utilizes " edge-emitting diode laser instrument " N-type semiconductor N lasing light emitter of a kind of being called mostly, this lasing light emitter has certain limitation, at first be that beam cross section is ellipse garden or rectangle shape, must come shaping with optical lens, need the optical element more than six to come work in addition in the Chang Gui optical picking-up head, these are laser diode, beam splitter, diffraction grating, catoptron, object lens and photodiode array, they understand CD information by the light intensity that determines the reflection of CD panel surface, and these discrete components cause optical picking-up head to become not only thick but also big.It is qualitative that As Bao Certificate laser Lose goes out the Steady of power in addition, Ji Guang Gong must Shall be installed Shuais Prison Visual Installed and put.
For realize one thin and little, the CD dish phonograph of pocket size, the necessary miniaturization of optical picking-up head of this CD dish phonograph, conventional optical picking-up head contains many element Hen Difficult microminiaturization, thereby need a big assembly, though limit emission laser diode and holographic cell assembly have made the optical picking-up head miniaturization become possibility, yet, a micromirror is built in the designing requirement of this unit in the substrate of the light-operated survey device of silicon, so that laser beam is being parallel to the substrate directional steering, and be divided into three-beam (grating and 45 ° of catoptrons are done together), the micromirror structure relates to expensive and manufacture process fine work.
For remedying the inherent shortcoming with other above-mentioned in the prior art is very useful, in view of the above:
An object of the present invention is to provide improved light and reproduce pick-up head, a kind of optical read-write device of data storage medium promptly is provided, it can effectively overcome the above-mentioned shortcoming of prior art, has that volume is little, simple in structure, cost is low, the characteristics of good stability.
Another object of the present invention is the improvement that is specially adapted to the tracker of optical picking-up head.
Another purpose of the present invention is that opposite side emission laser hologram light reproduces head and reads modifying device with tracker.
A further object of the invention provides the simplification optical picking-up head of quite few element.
A further object of the invention be for vertical laser hologram optical picking-up head read provide modifying device with tracker.
Of the present invention have a purpose to provide according to the said apparatus and the improvement that reduce the optical picking-up head cost on materials again.
The object of the present invention is achieved like this, construct a kind of optical read-write device of data storage medium, comprise luminescence unit, optical detecting unit Yu Guang Learn system, it is characterized in that also comprising that the photoconduction that is used for Guang Tong Over Guang Learn Xi Tong De Twin Jiao Mirror Head guiding data storage medium that described luminescence unit is produced and will produces from described data storage medium is to described optical detecting unit.
According to optical read-write device of the present invention, it is characterized in that described luminescence unit is the vertical cavity surface light emitting laser, and be integrated on the same semiconductor substrate with described optical detecting unit.
According to optical read-write device of the present invention, it is characterized in that Side Mian Hair penetrates laser than being combined on the same substrate Yu Guang Inspection Measuring Qi Group after the described luminescence unit Shi The Over shaping.
According to optical read-write device of the present invention, it is characterized in that, described luminescence unit comprises first laser instrument in the middle of occuping and the second and the 3rd laser instrument that occupy its both sides, and described detecting unit comprises the first and second Guang Inspection Measuring devices and the symmetrical third and fourth Guang Inspection Measuring device that occupy its both sides that places apart minimum distance.
According to optical read-write device of the present invention, it is characterized in that, designing described bifocal lens head can be with the luminous current data access point that is transmitted on the described data storage medium of described first laser instrument, and will be transmitted to the first and second Guang Inspection Measuring devices in the described smooth sensing unit by the light that this data access point produces, the light that the described second and the 3rd laser instrument sends can be transmitted to simultaneously current left anchor point and right anchor point on the described data storage medium, and will be by described left anchor point, the light that right anchor point produces is transmitted to the third and fourth Guang Inspection Measuring device in the described smooth sensing unit.
According to optical read-write device of the present invention, it is characterized in that the light-sensitive surface sum of the described first and second Guang Inspection Measuring devices is identical with light-sensitive surface size described the 3rd, Si Guang Inspection Measuring device respectively.
According to optical read-write device of the present invention, it is characterized in that described minimum distance is 1 micron between the described first and second Guang Inspection Measuring devices.
According to optical read-write device of the present invention, it is characterized in that, described bifocal camera lens is loaded on the electromagnetic motion device, control the described bifocal camera lens of this device scalable at described luminescence unit and optical detecting unit; Group closes element and Number and deposits relative position between Jie Quality according to Chu, realizes described data storage medium is focused on and seek rail.
According to optical read-write device of the present invention, it is characterized in that, containing the semiconductor-based chip assembly of stating Hair light unit, optical detecting unit to some extent is loaded on the electromagnetic motion device, control this and install the distance of this subassembly, realize described data storage medium is focused on and seek rail with respect to described bifocal camera lens.
According to optical read-write device of the present invention, it is characterized in that described bifocal camera lens is the lens halves that processes one with the mold mode, its surface is coated with anti-reflection coating.
According to optical read-write device of the present invention, it is characterized in that described bifocal camera lens adopts non-spherical structure.
According to optical read-write device of the present invention, it is characterized in that described bifocal camera lens adopts non-spherical structure to add grating.
According to optical read-write device of the present invention, it is characterized in that, determine to seek whether deviation of rail according to the difference of the signal of described the 3rd, Si Guang Inspection Measuring device, determine to seek rail according to the difference of the signal of described first, second Guang Inspection Measuring device and whether correctly focus on.
According to optical read-write device of the present invention, it is characterized in that described luminescence unit comprises a laser instrument, described detecting unit comprises the first and second Guang Inspection Measuring devices and the symmetrical third and fourth Guang Inspection Measuring device that occupy its both sides that places central authorities.
According to optical read-write device of the present invention, it is characterized in that, also comprise one place described laser instrument light-emitting area can be with this luminous left side that is divided into, in, the grating of right three beams, design described bifocal lens head and light beam in described can be transmitted to current data access point on the described data storage medium, and will be transmitted to the first and second Guang Inspection Measuring devices in the described smooth sensing unit by the light that this data access point produces, described left light beam and right light beam can be transmitted to simultaneously current left anchor point and right anchor point on the described data storage medium, and will be by described left anchor point, the light that right anchor point produces is transmitted to the third and fourth Guang Inspection Measuring device in the described smooth sensing unit.
According to optical read-write device of the present invention, it is characterized in that, determine to seek whether deviation of rail according to the difference of the signal of described the 3rd, Si Guang Inspection Measuring device, determine to seek rail according to the difference of the signal of described first, second Guang Inspection Measuring device and whether correctly focus on.
According to optical read-write device of the present invention, it is characterized in that described bifocal camera lens satisfies following relation:
Wherein, Δ is the distance between laser instrument and the light Inspection Measuring device, and δ is described data storage medium two luminous point spacings, and d is the distance of bifocal lens and data storage medium, and b is a distance between bifocal camera lens and the laser instrument/light Inspection Measuring device, and M is an enlargement factor,
Described bifocal lens head spacing is arranged simultaneously
According to optical read-write device of the present invention, it is characterized in that, also comprise the thermal sensing element of the temperature of the substrate that is used to detect described luminescence unit of described installation and optical detecting unit.
According to optical read-write device of the present invention, it is characterized in that, also comprise near the optical detection device that is separately positioned on each described laser instrument and communicates with described laser instrument by waveguide.
According to optical read-write device of the present invention, it is characterized in that, also comprise with light emitting source, integrated control module and the signal amplification unit of photodetector.
According to optical read-write device of the present invention, it is characterized in that, also comprise on the bifocal camera lens that is located at described aspheric mirror in order to the grating of compensates to the influence of lens parameters.
Implement the present invention, with light emitting laser Yu the integrated (Huo of Guang Inspection Measuring device Group close) on same chip, also control element, signal amplifier and laser/Guang Inspection Measuring device can be integrated, become an integrated device, this sheet is produced in a large number, reduce energy loss widely, and improve the sensitivity of Guang Inspection Measuring device.Laser diode has more efficient and actuality Yu Guang Inspection Measuring device is to make with the structure of vertical cavity chamber surface light emitting laser on the technology.The wavelength of the laser diode that adopts can 480～980NM between or longer.Because light path design of the present invention can save two spectroscopes and other mirror, light Inspection Measuring device can receive more reflected signal from CD, can improve the resolution to the CD reading so greatly.The present invention adopts the bifocal camera lens that incident light and reflected light are separated, and incident light is gathered on the CD dish, reflected light is thrown on the light Inspection Measuring device on planar laser limit, can effectively eliminate the light feedback, and saving the light supervising device can save.Utilize principle of the present invention, bifocal camera lens and laser instrument/integrated of light Inspection Measuring device can be designed to read simultaneously two information on the session, thereby can increase twice and separate read rate, same principle, we can read four information simultaneously if add a laser instrument/Guang Inspection Measuring device, with this, we can improve and separate four times of read rates.If the bifocal camera lens among the present invention is used on existing Sony or the Philips shaven head, also can reaches the minimizing element, make the microminiaturized more purpose of light read head.Be wasted in transmission course with the luminous energy of existing CD optical read-write head 90% and compare, have 50% laser Bei Guang Inspection Measuring device to accept with the light path of bifocal lens of the present invention, ten required energy of light reduce 5 times, and utilization rate of electrical improves greatly.This can save the energy content of battery for CDMan laptop computer machine.In light path of the present invention, feed back to laser instrument for avoiding light, adopt thermistor to monitor substrate temperature, realize the monitoring of optical output power.This make we optical devices simply, at a low price.Among the present invention there be greater than 80% quantum effect De Guang Inspection Measuring device, therefore easier detection reflected signal.Both improved sensitivity, can reduce laser output power again, from and further save the energy that shaven head is consumed.The optical read-write device of forming based on, bifocal camera lens provided by the invention is particularly suitable for CDMan and laptop computer.
In conjunction with the following drawings and embodiment, can have more specifically purpose of the present invention, content and characteristics and understand, in the accompanying drawing:
Fig. 1 illustrate by traditional optical read-write head of being formed with edge-emitting laser, half-reflecting mirror original screen panel, 1/4 wavelength sheet principle schematic.
Fig. 2 is that the optics of optical read-write head shown in Figure 1 follows the rail principle schematic.
Fig. 3 has represented the modified index path of laser head on the existing a kind of Sony shaven head machine, laser instrument Yu Guang Inspection Measuring device be encapsulated on the same substrate.
Fig. 4 illustrates the simplification principle schematic (three light beams) of explanation first embodiment of the optical picking-up head of formation according to the present invention's instruction.
The another Real example that Fig. 5 Shi executes An the bright Real of this Hair of Zhao;
Fig. 6 is the structural representation of hot spot on the detecting device among Fig. 4;
Fig. 7 is the prior art optical principle synoptic diagram that condenser lens is divided transmission and method for reflection solution light feedback.
Fig. 8-Figure 11 is to be respectively the organigram of four embodiment of bifocal camera lens, and this bifocal camera lens has the dual-use function of divided beams and focusing.
Figure 12 illustrates the graph of a relation of burnt mirror focal length and laser detector spacing.
Figure 13 illustrates the example with spherical mirror composite construction bifocal camera lens.
Figure 14 illustrates the example that replaces a bifocal lens of three spherical lens formations among Figure 11 with aspheric mirror.
Figure 15 illustrates explanation, and second embodiment of formation promptly is divided into a branch of light with grating the simplification principle schematic of the embodiment of three-beam according to the present invention's instruction.
Figure 16 illustrates laser instrument/light Inspection Measuring device array in embodiments of the present invention and constitutes the synoptic diagram of integrated component with thermistor monitoring laser output power.
Figure 17 illustrates the principle schematic of coming the laser power monitoring composition element with three light Inspection Measuring devices and optical waveguide in embodiments of the present invention.
Figure 18 illustrates one of structural drawing example of surface-emitting laser/Guang Inspection Measuring device.
Figure 19 is surface light laser optical electrical characteristics figure.
With reference to these accompanying drawings, identical label list is shown in identical or corresponding components in several views among the figure.
At first with reference to Fig. 1, Fig. 1 illustrates a kind of principle of work situation (Now You Ji Intraoperative of edge-emitting diode laser light pick-up head 10 of routine).Edge-emitting diode laser instrument 19 is along a paths emission of lasering beam, and this path is connecting an original screen panel 191 a branch of light is divided into three-beam.Laser beam is mapped to quarter-wave lengthy motion picture 14 by prism 15, and polarizing mirror 13 and object lens 12 that the latter further changes laser beam focus on the surface of data storage medium 11 (for example CD dish).Laser beam further changes the polarization of laser beam from 11 reflections of CD dish by quarter-wave lengthy motion picture 14 latter.Laser beam at right angles changes direction by prism 15 reflections with projecting beam, and last light is led on the photodiode array (18).Light intensity changes the step of reflection this system from " hole " to " land " (or opposite) by the photoelectricity of the photodiode on quadrant (four minutes) the photoelectric detector plate 18.This has illustrated the mechanism of the edge-emitting diode laser light pick-up head 10 in the structural arrangements of routine.Laser beam is a kind of divergent beams, has the different in nature angle of divergence.Divergent beams from laser diode 19 are a kind of linearly polarized laser beam, it is fallen on grating 191 and the collimation lens 192, these lens are transformed to the beam of substantially parallel light ray with it, laser beam then is directed into prism 15, be injected into then on the quarter-wave lengthy motion picture 14, the latter is transformed to the circular polarisation laser beam with laser beam, falls afterwards on the condenser lens 12.Beam by object lens 12 is a narrow beam, and it has round cross section basically, then focuses on the CD dish 11, and CD dish 11 has a luminous point, and diameter is about 1 micron.Wherein, the information on the CD dish 11 is encoded by " land " and " hole " of mint-mark on this panel surface, for the recorded information that is stored on this panel surface, and " land " and " hole " or reflect focalization laser beam, or make the scattering of laser focusing beam.Be mapped to quarter-wave lengthy motion picture 14 from the beam of panel surface reflection by object lens 12, whereby, change back to the linear polarization beam from the circular polarisation beam.Reflex to photoelectric detector 18 from the converted beam of quarter-wave lengthy motion picture 14 by beam splitter 15, thereby obtain data-signal.Circular detail box among Fig. 1 has provided the quadruple photo-detector of being made up of six photodetectors 18 and has formed situation.Quadruple photo-detector 18 is made up of six photodetectors.Be provided to the luminous point of the incident beam on the quadruple photo-detector 18, because the effect of condenser lens 12 is being changed to another kind of oval from ellipse in shape by a real circle.Be used to from photoelectric detector D
101And D
103Deduct from photoelectric detector D with signal
102And D
104Adjust focusing with signal.Then, the condenser lens 12 utilization difference that is arranged in the reproducing signal sum (the signal sum of being come by either side) of two relative photodetectors on the hemisphere face (second hemisphere face that it is relative) of quadrant is adjusted.Focus error signal only is adapted to the control device of focusing objective len displacement.
Above said focus servo be that the focus of laser beam is dropped on the CD card all the time, tracking servo then is that the luminous point of laser beam is penetrated all the time on the information line of CD.The width of optical disc information line is 0.4 μ m, and tracking accuracy must be within 0.1 μ m, and this has just proposed very high requirement to tracking servo system.Be to realize following the tracks of in CD player by the displacement of camera lens on direction of feed in the fine setting laser head.Around a tracking coil, add electric current to coil in the direction vertical with focusing coil, the tracking coil can move in the horizontal direction together with camera lens under the effect in magnetic field.Be added to direction of current and size in the coil, corresponding with tracking error signal, by the servo tracking error of eliminating.Here the detection of error is a very important ring equally.
Fig. 2 shows the described optical picking-up head of Fig. 1 and carries out the principle that tracking error detects, as shown in the figure, the laser beam that laser diode produced in laser head splits into three-beam behind grating, and shines simultaneously on the CD card, shines on the photodiode assembly after being reflected again.This is in this group light beam, and middle light beam is used for reading audio and video information and focus error message, and the auxiliary beam of both sides is used for detecting tracking error specially.
The detection of tracking error is arranged on the D of Guang Inspection Measuring device both sides
105, D
106Finish D
105, D
106Output deliver to the input end of differential amplifier (error amplifier) respectively.When tracking was correct, main beam was mapped on the information line, and the light beam that reflects shines D
101, D
102, D
103, D
104On the compound tube, and auxiliary beam is symmetrical in main beam and shines on the information line, and the amount that two auxiliary beams depart from equates, so shine D after the reflection
105, D
106On luminous flux equate that also error amplifier is output as zero, sees Fig. 2.
If the light beam of trace information line departs from, then D
105, D
106Output just unequal, the situation of right avertence takes place in (2.ii) among the figure, (2.iii) situation of left avertence for taking place in pin.D when left avertence takes place
105-D
106Output negative pole (error signal), D when right avertence takes place
105-D
106Be output as positive polarity.This error signal forms the drive signal of tracking coil through digital processing and D/A conversion, delivers to after amplifying and goes to proofread and correct tracking error in the tracking coil.The tracking coil is that object lens and magnetic core are configured to one on the magnetic core frame of horizontal direction.When in the coil electric current being arranged, because coil magnetic field can make the object lens along continuous straight runs move to the effect of permanent magnet, when sense of current changed, the direction that object lens move also changed.The driving of the detection of tracking error and tracking coil is constituted an automatic control loop, Here it is tracking servo system.
Fig. 3 illustrates improved index path on a kind of Sony machine shaven head, limit emission light laser 21, add grating 33 by 45 ° of prisms, a branch of light is divided into three beams and changes 90 ° and change 90 ° by (24) first on prism and penetrated amasthenic lens 26 and throw on the CD dish 35, the light of reflected back is mapped on the Guang Inspection Measuring device 32 by second face of prism 34, this design of Sony saves many optical elements, with Ji light Yu Guang Inspection Measuring device be made on the same base plate, strided forward an important step to microminiaturization, its shortcoming is divided beams and the used prism cost of manufacture height of commentaries on classics light beam, and the method for incident light and reflected light being separated with prism makes 90% light loss lose.
In Fig. 4, with label 40 the present invention is shown and adds first embodiment that light that bifocal lens constitutes picks up head with planar laser/Guang Inspection Measuring device integrated component, planar laser/Guang Inspection Measuring device integration member comprises three surface-emitting lasers 41,42,43 come on same the straight line, four Ge Guang Inspection survey device (44,45,46,47) on the line that quilt comes with laser instrument parallels, the required power of laser is about 1 milliwatt, laser instrument 42 He Guang Inspection Measuring devices 45 in the middle of occuping, 46 are used for understanding and focus adjustment, control, laser instrument 41/ Guang Inspection Measuring device 44 is used for following rail with laser instrument 43/ 47 pairs of Guang Inspection Measuring devices, the distance that swashs light and light Inspection Measuring device is approximately the distance of more than ten μ m, accurate numerical distance depends on the parameter of bifocal lens, we will make our desired Guang Inspection Measuring device with resonant cavity photodiode RCPD structure, because light emitting laser has identical production routine with RCPD, and RCPD has very high sensitivity (＞85% quantum effect), the wavelength selectivity of this Guang Inspection Measuring device is also very high, the light Guang Inspection Measuring device 45 that sends of test surface illuminator only, 46 altogether apertures equal the aperture of Guang Inspection Measuring device 44 or 47, the spacing that is about several micron (μ m) Guang Inspection Measuring devices 45 and 46 is less than 1 micron, bifocal camera lens 48 is made up of aspheric lens halves, the focal length of this lens halves has a fixing distance, the direction of this distance is parallel with laser instrument/light Inspection Measuring device direction institute, and the size of focal length provides institute's incident and required the separating of reflected light between the bifocal camera lens.Bifocal lens has very big numerical aperture (being about 0.5), so big aperture can be so that less laser facula impinges upon on the CD CD, the bifocal camera lens of aspherical shape is the aberration of compensation optical system, and these will make hot spot reach the limit of scattering elephant, have compensated the aberration of optical system.
Bifocal camera lens or laser/light Inspection Measuring device integrated component can be contained on the electromagnetic motion parts, is used for making laser to gather on the CD CD, and hot spot is thrown on session.
Explanation according to Fig. 4, the bifocal lens on a left side half is thrown into laser beam on CD (49) dish, and right half lens are used for CD is coiled the light of reflected back and project Guang Inspection Measuring device 44,47 detecting lasers 41 and 43 light that send on the Guang Inspection Measuring device, and two semicircles of apart very near (less than 1 μ m) or half elliptic Guang Inspection Measuring device 45,46 are as shown in Figure 6, be used to survey the light that sends from laser instrument 42, the ellipse of sensitive face central authorities is the hot spots from laser instrument 42 among Fig. 6, it is 3 μ m that this hot spot is acted in an unreasonable way to size, and longitudinal size is 1.5 μ m.
Adopt the design of bifocal camera lens according to the present invention, different with the CD player of any routine, light path herein makes does not have light to turn back to laser instrument from the CD dish, has avoided the instability of laser power, as everyone knows, the laser that turns back to laser instrument will cause the instability of laser power.In order to make laser power stability, on traditional CD player, laser power optical monitoring device is housed all, as shown in Figure 7, can make that like this output power is more stable, condenser lens 612 is divided into only can allow two parts of light incident and reflection, can avoid the light feedback like this.And in our design, the device of this similar condenser lens can save, and this has reduced the complicacy of system again.
In order to use laser 41/ Guang Inspection Measuring device 44 to follow rail with laser 43/ 47 pairs of Guang Inspection Measuring devices, they are installed at an inclined to one side little angle Ji Guang Guang Inspection Measuring device slice, thin piece along the track tangent line, just we draw on a CD hot spot offset track left side 0.5 micron and 33 take over 0.5 micron with laser, 42 dozens of laser are Yong Guang Inspection Measuring device 44 and 47 difference, i.e. D in orbit
44-D
47Signal is sent bare headed control coil back to just can realize following rail.
D
44-D
47＞0 takes back
D
44-D
47＜0 takes over
D
44-D
47=0 hits exactly at track
Can focus on by Yong Guang Inspection Measuring device 44,46 differences control hot spot simultaneously.
D
45-D
46＞0 is far away burnt,
D
45-D
46＜0 is near burnt,
And we use D
45+ D
46Signal is understood the information of CD.
Should be noted that the bifocal lens that the present invention adopts not only can separate incident and reflected light, and light can be gathered to CD that bifocal lens has been eliminated light and turned back to laser instrument in addition, thus stabilized lasers power.Specifically, utilize the advantage of bifocal lens to comprise: (1) bifocal lens provides the data deciphering simultaneously, followed rail and has focused on three big functions; (2) laser instrument, is easy to produce in enormous quantities with plated film, microelectronic technique with Guang Inspection Measuring device integrated component is to be made on the same substrate with same technology; (3) because laser instrument/light Inspection Measuring device integrated component light weight, size are little, this chip can be placed on and follow rail and focusing on the dynamic coil, because this element inertia is little, we can be easy to quick adjustment, and this can accelerate to follow rail and focusing process.In addition, this quick adjustment can compensate the derailing that big vibration produces; (4) owing to use bifocal lens, the reflected light of CD CD can not got back to laser instrument, and this has just eliminated the light feedback, with having reduced the complicacy of CD shaven head, can save the light supervising device.
Fig. 5 illustrates the Ge Real example that the bright laser instrument/optical integrating element of this Hair is arranged by string United form.Planar laser 411,412,413 and Guang Tan Measuring device 414,415/416 Right and 417 come on the straight Line of Yi Strip.415/416 Guang Tan Measuring device is perpendicular to 411, the 417 straight Line that arrange.Light is visited Measuring device 414 and 417 and is accepted Come respectively from laser instrument 411,413 light by light Disk reflected back.D414 and D413 letter No. Zhi Cha Decision decide Look Rail, and Guang Tan Measuring device 415 and 416 Tong Time receive Come certainly in the light of laser instrument 412 From Guang Disk reflected backs.The Cha Come Decision of D415 and D416 focuses on surely.D415 and D416 sum Come Decision are Dinged Xie Read Guang Disk information.Different with Fig. 4A, BL Twin is burnt, and Mirror Head need want Turn to lay for 90 °, so that make branch light direction and laser/light visit the Measuring device.
Fig. 8-11 has showed the bifocal camera lens of four kinds of structures respectively, the arrangement of these bifocal lens design all can reach the function of beam split, focusing, in order to make light as much as possible enter the CD CD, and reflected light received by light Inspection Measuring device, and surface that can camera lens plates antireflection film.And all available injection molded processing of these four kinds of lens design.
Figure 12 shows the relation that constitutes between bifocal lens focal length and the laser instrument/Guang Inspection Measuring device, suppose laser 112 Yu the distance between the Guang Inspection Measuring device 113 is a Δ, 118 liang of focal length 111 spacings of bifocal lens are δ b, and distance is b between bifocal lens 118 and the laser instrument/Guang Inspection Measuring device, laser is thrown into CD and is coiled between 117 two luminous points 115,116 distances and be δ, distance is d between bifocal lens 118 and the CD CD 117, and at this moment, laser instrument is with Guang Inspection Measuring device satisfies following relationship:
Wherein
Be magnification
The bifocal lens spacing
This bifocal lens is easy to be made by the way of plastic injected die, Figure 13 and Figure 14 have represented conventional spherical mirror system and the difference on the aspheric mirror structure fabrication respectively, can see if use spherical mirror, necessary with 3 lens, reach an aspheric mirror and reach the optics requirement, this shows that the way with aspheric mirror can make easy, the easy making of optical system.
Figure 15 illustrates explanation and constitutes i.e. second embodiment of another kind of design proposal according to thought of the present invention, in this embodiment, grating 1402 covers a surface light emitting laser 1401, a branch of light is divided into three-beam 141,142,143, intermediate beam (142) is used for focusing on and understands, about two auxiliary beams (141,143) be used for following rail, this design can replace three laser instruments with surface-emitting laser.Other device is with to read, follow described first embodiment of rail and focusing principle and Fig. 4 identical.
Because it is stable that variation of temperature can influence laser output power, for surface light emitting laser, temperature variation makes the optical maser wavelength displacement.Because variation of temperature can influence laser output power, for surface light emitting laser, temperature variation not only makes the optical maser wavelength displacement, and can cause the emission multi-mode laser, the increase of temperature makes the laser resonator size extend, and has caused other mould laser to send thus, and luminous power increases, because this variation is discontinuous, cause mode hopping, and produce the noise fluctuation, the noise that causes for fear of temperature, generally adjust input current, see Fig. 6 with the optics power monitoring.
Cause noise phenomenon for fear of temperature among the present invention, will adopt following method: (1) comes monitoring temperature with high precision thermosensitive resistor, monitors output power then, and its principle is seen Figure 16.Use the bifocal lens design, can eliminate the light feedback, so monitoring temperature enough makes optical output power keep stable.(2) also can make a Guang Guang Inspection Measuring device on the laser instrument limit, come the monitoring laser output power by waveguide.See Figure 17.
Figure 18 is that one of key element of plug-in reader shaven head is a surface-emitting laser/Guang Inspection Measuring device integrated component, and laser head commonly used now is to use the side laser instrument, and we can produce the surface light emitting device of 0.4 to 0.98 micron wave length now or in the future.They are to use GAAS/GAALAS, and INGAAS, GAINP and ALGAAS, INP material make a plurality of quantum wells formations of folder in the multilayer mirror.The surface light emitting array is with traditional molecular formula extension (MBE) or molecule organic vaporizing coating technology (MOCVD) and ion etching technology, makes our required array.
Compare with the lateral emitting device, the surface light emitting device can be done 10 microns garden shape diameter, and the lateral emitting device only can be accomplished 10 microns wide 1-200 microns and grows up little.Surface light emitting device sharpest edges are that xsect is the garden shaped light beam, and Vertical Launch can be made the laser instrument of two-dimensional array, and can be with operation circuit, and signal amplifier and Ji light Qi Guang Inspection Measuring device are integrated on the same chip.
Laser instrument Yu Guang Inspection Measuring device be made on the same chip, this is to propose (1996) by ORITZ, this resonance cavate light light Inspection Measuring device (REPD) has up to 85% quantum conversion ratio, is higher than existing photomultiplier (PMT) and avalanche diode light Inspection Measuring device (APD) far away.
Structure is to add quantum well with molecular formula extension or the molecule coating art long multilayer mirror on the GaAs substrate that organises, and constitutes " sandwich " structure adding catoptron.Add the plating tunic with ion injection and photoetching and can make light Inspection Measuring device and laser instrument integrated component.
Another advantage of this technology is that we can send out control element, signal big device and Ji Guang Guang Inspection Measuring device integrates, and becomes an integrated device, and thus, we can reduce energy loss widely, and improve the sensitivity of Guang Inspection Measuring device greatly.These are the advantages with surface light emitting laser.Different with traditional C D shaven head, because light emitting laser and light Inspection Measuring device are made on the same chip, laser diode and light Inspection Measuring device can be made with the structure of vertical cavity chamber surface light emitting laser.The wavelength of laser diode can 480～980NM between or longer.Because our light path design can save two spectroscopes.So and other mirrors we can receive more reflected signal from CD by De Guang Inspection Measuring device, can improve greatly like this and read resolution.Again since with the bifocal lens head with incident and reflect and to separate, so the light of returning from CD reflection can be mapped near the laser on the De Guang Inspection Measuring device.
Figure 19 has represented the characteristics of luminescence of existing emitting laser.Inject the electric current of 10 milliamperes as seen from Figure 19, do under the power supply at about 4 couchers, we can obtain the laser of 3 milliwatt power.
Those skilled in the art can be easily to carrying out various changes and modification in order to describe the employed embodiment of purpose here, do not depart under the present invention spirit prerequisite in such modifications and changes, they all implied meaning they be included in the scope of the present invention of claims regulation.
Claims (18)
1, a kind of optical read-write device of data storage medium, comprise luminescence unit, optical detecting unit, its feature also comprises and is used for the photoconduction that produces by the just described luminescence unit of bifocal camera lens to data storage medium and the described bifocal camera lens of guides reflected light and the optical detecting unit that will produce from described data storage medium.
2, optical read-write device according to claim 1 is characterized in that, described luminescence unit is the vertical cavity surface light emitting laser, and is integrated on the same semiconductor substrate with described optical detecting unit.
3, optical read-write device according to claim 1, it is characterized in that, first laser instrument in the middle of described luminescence unit occupy and the second and the 3rd laser instrument that occupy its both sides, described detecting unit comprise first and second photodetectors and symmetrical third and fourth photodetector that occupy its both sides that places apart minimum distance.
4, optical read-write device according to claim 3, it is characterized in that, design described bifocal lens head and the light that described first laser instrument is sent can be transmitted to current data access point on the described data storage medium, and will be transmitted to first and second photodetectors in the described photodetector unit by the reflected light that this data access point produces, the light that the described second and the 3rd laser instrument sends can be transmitted to simultaneously current left anchor point and right anchor point on the described data storage medium, and will be by described left anchor point, the light that right anchor point produces is transmitted to third and fourth photodetector in the described optical detecting unit.
5, optical read-write device according to claim 3 is characterized in that, the light-sensitive surface sum of described first and second photodetectors light-sensitive surface size with described the 3rd, the 4th detecting device respectively is identical.
6, optical read-write device according to claim 3 is characterized in that, described minimum distance is 1 micron between described first and second photodetectors.
7, optical read-write device according to claim 1, it is characterized in that, described bifocal camera lens is loaded on the electromagnetic motion device, control the relative distance position of the described bifocal camera lens of this device scalable between described luminescence unit and optical storage media, realize described data storage medium is focused on and seek rail.
8, optical read-write device according to claim 1, it is characterized in that, the semiconductor-based chip assembly that contains described luminescence unit, optical detecting unit is loaded on the electromagnetic motion device, control this and install distance and the position of this subassembly, realize described data storage medium is focused on and seek rail with respect to data storage medium, described bifocal camera lens.
9, optical read-write device according to claim 1 is characterized in that, described bifocal camera lens is the lens halves that processes one with the mold mode, and its surface is coated with anti-reflection coating.
10, optical read-write device according to claim 1 is characterized in that, described bifocal camera lens adopts non-spherical structure.
11, optical read-write device according to claim 1 is characterized in that, follows the tracks of the read-write light beam according to the difference of the signal of described the 3rd, the 4th photodetector, to determine whether off-track.Whether correctly come to focus on the specified data storage medium according to the difference of the signal of first, second photodetector.
12, optical read-write device according to claim 1 is characterized in that, described luminescence unit comprises a laser instrument, and described detecting unit comprises first and second detecting devices that place central authorities and third and fourth photodetector that is symmetrical in its both sides.
13, optical read-write device according to claim 12, it is characterized in that, also comprise one place described laser instrument light-emitting area with the luminous left side that is divided into, in, the grating of right three beams, design described bifocal lens head and light beam in described can be transmitted to the current data access point of described data storage on being situated between, and will be transmitted to first and second photodetectors in the described optical detecting unit by the radiating light that this data access point produces, described left light beam and right light beam can be transmitted to simultaneously current left anchor point and right anchor point on the described data storage medium, and will be by described left anchor point, the light that right anchor point produces is transmitted to third and fourth photodetector in the described optical detecting unit.
Whether 14, optical read-write device according to claim 12 is characterized in that, determines to seek whether deviation of rail according to the difference of the signal of described the 3rd, the 4th photodetector, determine to focus on correct according to the difference of the signal of described first, second photodetector.
15, optical read-write device according to claim 2 is characterized in that, also comprises the temperature thermal sensing element that is installed on described luminescence unit and the optical detecting unit substrate, is used to monitor the temperature variant characteristic of described luminescence unit output power.
16, optical read-write device according to claim 2 is characterized in that, also comprises being separately positioned near each described planar laser and by waveguide and the optical detection device that described laser instrument communicates, and is used to monitor the output power of described planar laser.
17, optical read-write device according to claim 2 is characterized in that, also comprises with light emitting source, integrated control module and the signal amplification unit of photodetector.
18, optical read-write device according to claim 15 is characterized in that, also comprises on the bifocal camera lens that is located at described aspheric mirror in order to the grating of compensates to the influence of lens parameters.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98115719 CN1240291A (en) | 1998-06-23 | 1998-06-23 | Optical read/write device for data storage medium |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 98115719 CN1240291A (en) | 1998-06-23 | 1998-06-23 | Optical read/write device for data storage medium |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102831903A (en) * | 2011-06-13 | 2012-12-19 | 希捷科技有限公司 | Head gimbal assembly with heat assist laser |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102831903A (en) * | 2011-06-13 | 2012-12-19 | 希捷科技有限公司 | Head gimbal assembly with heat assist laser |
| CN102831903B (en) * | 2011-06-13 | 2015-09-23 | 希捷科技有限公司 | Data storage device, data storage device and forming method thereof |
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