CN103217818A - Method for increasing response speed of phase-control silicon-based liquid crystal device - Google Patents
Method for increasing response speed of phase-control silicon-based liquid crystal device Download PDFInfo
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Abstract
The invention discloses a method for increasing response speed of a phase-control silicon-based liquid crystal device. The method for increasing the response speed of the phase-control silicon-based liquid crystal device comprises the following steps of: S101, determining an adjustment step size m; S102, determining different response intervals according to the thickness and the working temperature of the phase-control silicon-based liquid crystal device by combining the adjustment step size m; and S104, selecting one response interval with the fastest response speed change in all the response intervals to serve as a working interval of phase-control conversion. According to the method for increasing the response speed of the phase-control silicon-based liquid crystal device disclosed by the invention, by adopting an electrically controlled birefringence (ECB) mode, on the basis that original advantages of continuous phase debugging, extremely low quantization errors, high light transmission efficiency, all-phase debugging and the like are met, the goal that the speed of the device is increased is achieved.
Description
Technical field
The present invention relates to technical field of liquid crystal display, particularly relate to a kind of method that improves phased silicon-based liquid crystal device response speed.
Background technology
LCOS(Phase Only Liquid Crystal On Silicon, the phase control type silicon-based liquid crystal device) technology was developing aspect image and the video demonstration nearly 20 years, with traditional LCD(Liquid Crystal Display, liquid crystal display) flat panel display difference, it has not only utilized the photoelectric characteristic of liquid crystal material uniqueness, combine high-performance simultaneously, multi-functional CMOS(Complementary Metal Oxide Semiconductor, complementary metal oxide semiconductor (CMOS)) advantage of integrated circuit, utilize the deflection of electric signal control liquid crystal material, in the process of this variation, incident light is carried out full phase place, continuous debugging, on principle, be best for the utilization ratio of light.Therefore the application function of this device has enriched many again than traditional LCD demonstration and the demonstration of LCOS image.At present occupy certain advantage at aspects such as optical communication, line holographic projections.
The LCOS device probably is divided into two classes: the first kind is that the amplitude of light is debugged, promptly above-mentioned traditional LC OS display device; Second class is only the phase place of light to be debugged.The LCOS of amplitude debugging passes through linear polarizer, after the linear polarization direction of incident light is debugged, and last output polarization optical information, this is similar to current LCD displaying principle; The LCOS device of phase place debugging then changes the birefraction of liquid crystal molecule by the electric signal that is carried on the cmos circuit, thereby reaches the effect that postpones the incident light phase place,
Because the birefraction variation range of liquid crystal material is bigger, therefore use liquid crystal material in the phased LCOS device usually as the light transmission media.Because in the middle of the LCOS device of phase place debugging, polaroid and other optical device do not have light absorption, light transmissioning efficiency is maximum like this.Therefore, phased LCOS device is one of developing direction of following photo engine.
The structure of phased LCOS device as shown in Figure 1, different with " sandwich " structure of traditional LC D device is, changes one deck glass substrate wherein the silicon substrate of CMOS integrated circuit into, is the reflectivity device.For the pel array of silicon backboard (silicon substrate) circuit that makes LCOS reaches maximum fill factor, electronic circuit is arranged on the bottom of aluminum pel array.When incident light enters the liquid crystal material layer of zero absorption, analog drive voltage is loaded on each pixel of silicon backboard, by electric field liquid crystal material is deflected, like this can be so that phase delay takes place in incident light in the process of liquid crystal deflecting element.
Liquid crystal material is a kind of state of matter that is situated between between solid and liquid.The state of liquid crystal material is divided into the nematic crystal attitude again, smectic crystal attitude (Smectic Phase) etc.As a rule liquid crystal state is distinguished in the orientation in space by molecule, and promptly the molecule center of gravity is in spatial distributions.Molecule such as nematic crystal is to grow thin excellent type, and the distribution of their molecule is to point to certain direction.Because liquid crystal molecule is the form with liquid at high temperature, promptly (the Isotropic Phase) of any direction attitude so will keep certain specific direction attribute of liquid crystal, need remain on environment temperature within the scope.
As shown in Figure 2, be example with the nematic liquid crystalline material, it is one of common liquid crystal state, its molecule is that bar-shaped, its arrangement has certain orientation.Main photoelectric material in the current liquid crystal device is the nematic crystal molecule, blue phase liquid crystal molecule or cholesterol liquid crystal molecule.n
eBe special refractive index, it is parallel to the electric field polarization direction of liquid crystal molecule direction; n
oBe common refractive index, it is perpendicular to the electric field polarization direction of liquid crystal molecule direction.The two-fold rate is the poor of two numerical value.Because nematic liquid crystalline material possesses the advantage of continuous phase debugging, adopted by increasing silicon-based liquid crystal device (LCOS) in recent years.
The selection of liquid crystal material is the most important part of phase control type LCOS device performance, and the liquid crystal material that is applied in this device must satisfy following requirement:
1, high birefringence rate (thickness of detector is thick, and response device speed is slow):
D is the thickness of device, and γ is the specially moving viscosity of liquid crystal material, and Δ ε is a specific inductive capacity, K
IiBe the elasticity coefficient of liquid crystal material, τ
RisingAnd τ
DecayIt is rise response time and decline response time.Derive thickness in the formula and speed is directly proportional.
2, high-k (threshold voltage is low):
Drawn by publicity 1 and 2, specific inductive capacity and speed are inversely proportional to.
3, this material require can both keep stable at visible-range and region of ultra-red:
A lot of liquid crystal materials are very unstable at the molecule expression power of infrared band.This has big influence for the application in the optical communication system, and it is most important therefore to be chosen in the stable liquid crystal of communication C-band (1530-1565nm).
Electrically conerolled birefringence rate (ECB, Electrically Controlled Birefringence) Pei Zhi LCOS device principle of work as shown in Figure 3, when not having voltage to load on device (" disconnection " state), liquid crystal molecule is arranged according to the direction of oriented layer, at this moment n
oBe parallel to the Z axle, n
eBe parallel to Y-axis.When aanalogvoltage loads on device (" conducting " state), along with the increase gradually of aanalogvoltage, n
oDirection is constant still to be parallel to the Z axle, and n
eGradually by parallel Y-axis to parallel Z axle, promptly the liquid crystal molecule among Fig. 3 " is stood " gradually, this moment the n in the process
eNumerical value to n
oNumerical value convergence (birefraction maximum again levels off to 0), when the device, two values equate, finish the deflection of liquid crystal molecule with voltage up to the maximum analog voltage loads, promptly incident light phase place debug process finishes.Owing to do not have the polarized light of other directions to produce in this process, therefore obtained the debugging scope (incident light phase place from 0 to 2 π) of maximum phase.The response speed of device is n
eTo n
oThe time of being experienced, i.e. the incident light time that phase place from 0 to 2 π is consumed after the debugging of LCOS device.
The response time of device is under the mode of operation of ECB, and in visible light and infrared scope, utilizes the loading of binary raster, drives each voltage level simultaneously and realizes.By measuring light intensity and the relation of response time, derive the relation of phase change and time response.This essential information will be brought huge facility to the holographic designs slip-stick artist, understand each pixel driving different voltage condition, accurately locate phase change speed.
The response speed of LCOS device is important performance index on the application directions such as demonstration, projection, hologram three-dimensional, communication.The method that improves LCOS response device speed at present mainly is the configuration that changes device architecture and liquid crystal material.More representational dual mode is the ferroelectric liquid crystals Surface Stablised Ferroelectric Liquid Crystal(SSFLC of surface-stable pattern) and the birefraction pattern Optically Compensated Birefringence(OCB of optical compensation).
Use SSFLC LCOS device, because its response speed and advantage of need not to add polarizer in system fast have certain status in phased LCOS device.But the critical defect of its device is: 1, the binary phase debugging only can be provided, and can't be in gamut (between 0 to 2 π) and continuous phase place debugging.Though sequence of subframes (Subframe Sequential) technology can provide the debugging of multivoltage and many grades phase place, and uses in line holographic projections, it has not only lost in the asymmetrical diffraction level light intensity of half; Need 90 ° of ferroelectric liquid crystal material deflections just can obtain the maximal efficiency (＜50%) of light simultaneously; Realize that above-mentioned application also need dispose very special ferroelectric material and just can reach in certain thickness device, and the response speed of this moment is similar with the LCOS device that uses the nematic liquid crystalline material configuration.2, because the sequence of subframes technology makes the voltage of device circuitry backboard by combination " two voltage debugging of 0 and 1 ", realize continuous phase place debugging, therefore device can produce huge quantization noise, so SSFLC is not suitable for fully among optical communication and high-quality image projection.
In the LCOS device of ECB configuration, glass is opposite with the oriented layer direction of silicon substrate.Therefore when driving element, the deflection meeting of liquid crystal molecule is hindered by a kind of torsion, thereby causes response device slack-off; And in the LCOS device architecture of OCB configuration: the oriented layer direction of glass substrate and the oriented layer direction of silicon-based substrate are consistent, when such device architecture makes liquid crystal deflecting element, can not produce this torsion, so the speed of device is to be improved.Generally speaking, in the OCB device, the angle of inclination of oriented layer is generally more than 8 °, and liquid crystal molecule can only be in crooked deformation (Bend Deformation) work down.Though the response speed of OCB device is very fast, it has following three kinds of fatal defectives: 1, scope less than 2 π of its phase place debugging.General in the LCOS of ECB structure device, the angle of inclination of oriented layer within 2 °, the phase place debugging of assurance 2 π that like this can maximal efficiency, and the oriented layer of OCB device generally will be arranged on more than 8 °, n like this
eThe reducing of numerical value caused reducing of birefraction, thereby influences phase place debugging scope; 2, device in working order in, liquid crystal molecule can produce distortion attitude (Twist State), this will cause producing the light of various polarization directions in the incident light debug process, thereby reduce the light debugging efficiency of device; 3, the high dip angle of the oriented layer friction process that is configured to oriented layer has brought huge difficulty, can cause the instability of pixel aluminium lamination in the technological process of its hot setting, destroys the reflectivity on pixel top layer.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of method that improves phased silicon-based liquid crystal device response speed, in order to solve the slow problem of phased silicon-based liquid crystal device response speed in the prior art.
For solving the problems of the technologies described above, on the one hand, the invention provides a kind of method that improves phased silicon-based liquid crystal device response speed, comprising:
Step S101 determines to adjust step-length m;
Step S102 according to the thickness and the working temperature of phased silicon-based liquid crystal device, in conjunction with adjusting step-length m, determines different response intervals;
Step S103 selects the interval interior response speed of each response to change the fastest interval operation interval as phased conversion of a response.
Further, each responds the interval and is respectively: (0,2 π), (m, 2 π+m), (2m, 2 π+2m) ..., (nm, 2 π+nm), and wherein, thickness of detector d=2 π+nm.
Further, after step S103, also comprise:
Driving voltage is increased to maximum load voltage Vmax, finishes maximum voltage and drive process;
Driving voltage is reduced to the target phase value, i.e. target voltage values Vi; The time that this moment, device needed is t
D_it
D_iBe the response time when from the maximum voltage to the gray shade scale, being i, i=0 wherein, 1,2 ..., 255;
Get phase delay to the end.
Further, before driving voltage being increased to maximum load voltage Vmax, also comprise:
Carry out dc balance and handle, make the alternating electric field symmetry that loads in the silicon-based liquid crystal device on the liquid crystal material.
Further, load voltage by maximum load voltage when target voltage values reduces, increase one or more intermediate voltage values, load voltage drops to intermediate voltage value earlier by maximum load voltage, reduces to target voltage values again; Simultaneously, in the waveform forward position of the square wave voltage waveform of driving voltage and back along increasing other predetermined intermediate value, the phase swing when reducing steady state (SS).
Further, in the CMOS backboard of silicon-based liquid crystal device, the size of Pixel Dimensions between 1 micron to 20 microns, unit pixel be shaped as rectangle or square.
Further, the liquid crystal material of silicon-based liquid crystal device is nematic liquid crystalline material, blue phase liquid crystal material or cholesterol liquid crystal material.
Further, the oriented layer of silicon-based liquid crystal device is made up of high molecular polymer, and the friction mode of oriented layer is vertical with the direction vector of liquid crystal molecule; When liquid crystal material was applied in the structure of automatically controlled property birefraction, the initial friction angle of oriented layer was 2 °; When liquid crystal material was applied in the device of optical compensation structure, the initial friction angle of oriented layer was not less than 8 °.
Further, the driving voltage of silicon-based liquid crystal device is sinusoidal wave pulse, triangular pulse or square-wave pulse.
Further, the phased LCOS device under mimic channel drives, maximum voltage is 7V, gray level from 0 to 255.
Further, maximum load voltage Vmax is that gray-scale value is 255 or 189 pairing load voltage values.
Beneficial effect of the present invention is as follows:
The present invention adopts ecb mode, is satisfying on the former bases that have superiority such as continuous phase debugging, extremely low quantized error, high light transmissioning efficiency, full phase place debugging, has reached the purpose of device speed-raising.
Description of drawings
Fig. 1 is the basic block diagram of LCOS in the prior art;
Fig. 2 is the single shaft light index map of single liquid crystal molecule refractive index in the prior art;
Fig. 3 is the LCOS device work synoptic diagram of electrically conerolled birefringence rate configuration in the prior art;
Fig. 4 is the response time synoptic diagram that adopts prior art;
Fig. 5 is the response time synoptic diagram that adopts embodiment of the invention scheme;
Fig. 6 adopts the response time that prior art and embodiment of the invention scheme obtain and the comparison diagram of phase control range respectively;
Fig. 7 is the comparison diagram of embodiment of the invention medium-high frequency component in analog-and digital-circuit;
Fig. 8 is the comparison diagram of different loads following response time of voltage and the phased degree of depth in the embodiment of the invention;
Fig. 9 is the graph of a relation that the debugging of driving voltage and phase place changes in the embodiment of the invention;
Figure 10 is response intervals different in the embodiment of the invention and the graph of a relation of response time.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, does not limit the present invention.
In the LCOS device of ECB configuration, the size of load voltage becomes the monotone increasing relation with the scope of light phase debugging, and promptly voltage improves, and the phase place debugging degree of depth increases.The inventor is through a large amount of experiments, and the response time of finding liquid crystal material is that the raising according to load voltage reduces, and promptly improves the response that voltage loads can be quickened device, reduces the response that the load of voltage has then slowed down device.That is: under the situation of load voltage greater than threshold voltage, if load voltage is improved, the response of liquid crystal material will be accelerated; This relation is a monotonically increasing.Therefore, when prior art is debugged little phase change at device, because the required voltage of device is very low, so that response speed becomes is very slow.The present invention has solved the phased silicon-based liquid crystal device of present main flow and has produced the slow excessively problem of response speed by its type of drive according to the relation of load voltage and response time, reaches the effect of response device speed-raising.The accelerating method that adopts mainly is to select to attempt at change device architecture and liquid crystal at present, and two kinds of methods (SSFLC and OCB) of main flow all have huge defective; And the present invention is adhering to adopting ecb mode, the liquid crystal molecule that collocation satisfies condition, satisfying on the former bases that have superiority such as continuous phase debugging, extremely low quantized error, high light transmissioning efficiency, full phase place debugging, change cmos circuit by the following method to drive, reached the purpose of device speed-raising.
In the LCOS device of amplitude debugging, response speed is defined as the transmission light intensity and changes to the maximum time of being experienced from 0.In the LCOS device of phase place debugging, the light intensity that then is defined as first-order diffraction is from 0 to time that maximum experienced.Because the grating information that loads is to be finished by the voltage of driving element, so the relation of the variation of diffraction intensity and load voltage can change by mathematics, is derived as phase delay and time relation.Industry, the basic span of response speed intensity transmission 10% to 90% between because the progressive band of zone of saturation can cause the inaccurate of the number of degrees.
In the LCOS device of phase place debugging, the embodiment of the invention changed at the time in 5% to 95% the diffracted ray strength range, can write down more phase place Debugging message like this, the raising of response speed is had more accurately judge.Rise time response be when voltage when 0 voltage rises to target voltage numerical value, the needed time of device; Be meant voltage fall time when target voltage is reduced to 0 voltage, the time that device needs.Under the situation of load voltage greater than threshold voltage, if load voltage is improved, the corresponding speed of liquid crystal material will be accelerated, and this relation is a monotonically increasing.
Embodiment one:
The embodiment of the invention relates to a kind of method that improves phased silicon-based liquid crystal device response speed: comprising:
Step S101 is increased to maximum load voltage Vmax to driving voltage, finishes maximum voltage and drives process;
In this step, the phased LCOS device under mimic channel drives, maximum voltage generally about 7V, gray level from 0 to 255; Be that voltage gradient is divided into 256 grades, the variable quantity of each step voltage is (7/255) V.Describe according to epimere, suppose that the trivial response time of device should be t
i, i.e. response time when load voltage gray shade scale (N) is i.Present type of drive, response device is fastest in debugging full phase place (2 π) numerical value, i.e. and maximum voltage load puts on the moment of device.According to this characteristic, before the debug target phase place, needed maximum load voltage when loading " debugging full phase place " numerical value earlier, and then the voltage of select target phase place correspondence are promptly realized device speed-raising process.
The required fastest response speed of device is t
N=t
255The result is t through experiment measuring fastest response speed
N=t
255=7ms.
In the silicon-based liquid crystal device, liquid crystal layer is clipped between electrode ITO layer and the aluminium lamination; Because the work function difference of these two kinds of materials, when symmetrical alternating voltage loaded on the liquid crystal layer by such asymmetric electrode, its actual on-load voltage was equivalent to former on-load voltage and has added a Dc bias, and liquid crystal material can't enter a stable status.Therefore, for obtaining better technique effect, this step also needs to carry out dc balance (DC balance), with the alternating electric field symmetrization that loads in the silicon-based liquid crystal device on the liquid crystal material.If do not carry out dc balance, the phenomenon of phase swing can be fairly obvious, causes the performance of device to descend.
Step S102 reduces to the target voltage values Vi that determines according to the device working temperature with driving voltage, realizes the set goal phase value; The time that this moment, device needed is t
D_it
D_iBe the response time when from the maximum voltage to the gray shade scale, being i, i=0 wherein, 1,2 ..., 255;
Because the continuous variation characteristic of phase place of liquid crystal material and the rotator inertia of liquid crystal molecule, and between interaction, after on-load voltage changed, liquid crystal material can produce in various degree " flyback " (flyback), caused respective phase swing (phase flicker).Therefore, in the present embodiment, load voltage by maximum load voltage when target voltage values reduces, increase one or more intermediate voltage values, to reduce transitional period (transient) phase swing.Simultaneously, can also be in the waveform forward position of the square wave voltage waveform of driving voltage and back along increasing other predetermined intermediate value, to slow down " flyback ", the phase swing when reducing steady state (SS).
Step S103 gets phase delay to the end.
The device load voltage from 0 voltage to V
iNeeded process is 0, Vmax, V
iTotal response time t
iFor:
Wherein, t
255Be that gray scale is the response time of 255 o'clock (maximum voltage).
In the present embodiment, when the silicon-based liquid crystal device temperature in that [15 °, in the time of in 55 ° the scope, along with the rising of temperature, the response speed of silicon-based liquid crystal device can be more and more faster.
Among Fig. 4 at voltage V
iDrive the response time t of device down
i(adopt prior art,, behind the wait liquid crystal response, obtain phase delay) promptly by loaded targets voltage; Be according to accelerating method among Fig. 5, earlier voltage be arranged at maximum V
Max(response time is t
255), wait-for-response time t
255, and then debug to target voltage V
i(response time is t
D_i), get phase delay to the end; Use this kind method at V
iResponse time t under the voltage
iEqual t
255With t
D_iSum.After actual computation, it is feasible and effective to draw the speed-raising scheme.
It is to be noted: as i=189 or when above, t
iResponse time do not needed through the speed-raising finish.The phase place debugging scope of this moment is 1.96 π, approximate full phase place the debugging scope 98%, considering that this has guaranteed the integrality of device work fully under the situation of error.This has proved that under the condition that does not influence the device serviceability speed-raising that realizes the response time is fully feasible.In the practical application, need before the concrete image information of scanning, load the driving voltage of a maximum, load the needed voltage of picture element matrix then and get final product to picture element matrix.Use this kind type of drive, might produce a responding time intervals, therefore be not suitable for the application of demonstration or projection aspect.The needed voltage value of phase delay (the pairing voltage value of i=189) that different devices is corresponding different, that is to say, the needed voltage value of phase delay has relation with concrete device, needs to do primary calibration before each the use, to determine this numerical value.
Among Fig. 6, open circle represents that according to existing type of drive voltage rises to the phase control range of target target voltage from original 0 voltage; Solid rim represents to adopt the scheme of the embodiment of the invention, and voltage is loaded as maximum voltage from 0 voltage earlier, and then reduces to the phase control range of target voltage; As can be seen from Figure 6, the speed-raising scheme of the embodiment of the invention raises speed on this device obviously, and during 189 gray levels, device has been finished whole phase control ranges substantially.During as little phase change, the 100ms rank that can raise speed (phase place debugging＜1 π), all the other tens ms(1 π that can raise speed substantially, 4 π) between.
In the present embodiment, in the CMOS backboard of silicon-based liquid crystal device, the size of Pixel Dimensions is between 1 micron to 20 microns, and the shape of unit pixel can be a rectangle or foursquare.The thickness of silicon-based liquid crystal device is generally between 1 micron to 5,6 microns; With the wavelength is benchmark, and wavelength is long more, and thickness of detector is big more, and thickness satisfies the 2pi phase control range, if in the application (being that wavelength is more than 3 microns) of microwave regime, the thickness of device can reach tens microns so.
The selection of silicon-based liquid crystal device can be nematic liquid crystalline material (for example this nematic liquid crystalline material of BLO37), also can be blue phase liquid crystal material (blue phase) or cholesterol type (chiral nematic) liquid crystal material.
The oriented layer of silicon-based liquid crystal device (alignment) generally is made up of high molecular polymer, the friction mode of oriented layer is vertical with the direction vector of liquid crystal molecule, the initial friction angle of oriented layer is generally less, liquid crystal material is applied in the structure of automatically controlled property birefraction, and generally they are about 2 °; If liquid crystal material is applied in the device of optical compensation structure, the initial angle of oriented layer generally can be less than 8 ° so, and rubbing angle is excessive, can lose the space phase debugging scope of device.
The layout of silicon-based liquid crystal device CMOS integrated circuit part can be rectangular, also can be foursquare, and the shape of pixel layer can be a rectangle or foursquare, under the specific demand, and the matrix that pixel layer can 1*N.
The pulse of the driving voltage of silicon-based liquid crystal device can be sinusoidal wave (sin) pulse, also can be triangular pulse or square-wave pulse.ITO(Indium Tin Oxide, indium tin oxide) electrode can be dot matrix (corresponding each pixel), also can be to cover glass substrate.
In addition, in the foregoing description, can also be increased in the process of maximum load voltage Vmax, load voltage is stopped at target voltage values, get phase delay to the end at load voltage.That is: in certain time interval, load the pulse of a series of maximum voltages, these pulses should load on before the required pulse voltage.
Because the response device time is the shortest when maximum voltage drives, and phase change can reach 2 π.Therefore analyze theoretically, in the process that loads excessive driving voltage, can select the middle pairing magnitude of voltage of phase depth arbitrarily of from 0 to 2 π, thereby realize the quick response of device.But when in side circuit drives, using this kind method, the requirement that tends to exceed target phase.However, we still can utilize this principle in the circuit of reality some high voltage pulses of load and realize the speed-raising.
If in the LCOS device, wave form varies speed is greater than the speed of response of liquid crystal material, when being the high fdrequency component of liquid crystal material in can't response wave shape, liquid crystal material is to respond according to the root-mean-square valve (RMS) that loads waveform arbitrarily, in this case, the method for response time speed-raising should not be used.If but comprise that in waveform the component of low frequency and the response speed of liquid crystal material molecules are similar to, then according to the instantaneous value response of waveform, " excessive " driven can realize Ci Shi liquid crystal material in this case so.
In high frequency analog circuits, liquid crystal can't corresponding high fdrequency component, if among Fig. 7, a figure equates that with the area of shade among the b figure they are equivalent for the driving of liquid crystal molecule so; Situation in high frequency digital circuits is the same with situation in the high frequency analog circuits, as long as c figure is identical with the area of shade among the d figure, their driving is equivalent.But in low frequency simulation or digital circuit, the response of liquid crystal molecule is relevant with independent component of voltage.
Among Fig. 8, X-axis (Time) express time; Y-axis (Phase Modulation) is represented the phased degree of depth.Lines near X-axis among Fig. 8 are represented: when load was 4.4v, the scope of phase place debugging can't reach full phase place debugging between (0,1.93 π), and needing the time is to finish within the 21.2ms.Lines in the middle of among Fig. 8 are represented: when load was 5.7v, phase place debugging scope satisfied full phase place debugging substantially, and needing the time is 9.7ms.Lines near Y-axis among Fig. 8 represent that when load was maximum 7v, phase place debugging model satisfied full phase place debugging, need the time only within the 4.6ms.By this experimental result as can be seen: utilize maximum load to drive, response speed is the fastest.If in the process of load maximum voltage, stop at the target phase place, can realize speed-raising.Such as the phase place debugging of needs 1 π, when adopting load 7v so, the speed that needs is about 2.3ms.
Embodiment two:
Consider the sum of errors optical environment error of production technology, generally, the thickness of silicon-based liquid crystal device can require bigger than normally than required, and the working range of device reaches 2 π, and the manufacturing thickness of device is often a little more than requirements; Be generally 2.5 π, even 3 π.So both guaranteed working performance of devices, and can make that again full phase place debugging scope was more flexible.According to these characteristics, in the embodiment of the invention, revised the interval of working range, original (0,2 π) is moved to (wherein, m adjusts step-length for m, 2 π+m).The purpose of doing like this, the slow response raising with low-voltage keeps working range constant simultaneously.
The embodiment of the invention relates to a kind of method that improves phased silicon-based liquid crystal device response speed: comprising:
Step S201 determines to adjust step-length m; Adjusting step-length m can be fixed numbers, also can be different numerical value, specifically determines method, is determined according to device characteristics by the technician.
Step S202 according to the thickness of phased silicon-based liquid crystal device, in conjunction with adjusting step-length m, determines different response intervals, for example, and (0,2 π), (m, 2 π+m), (2m, 2 π+2m) ..., (nm, 2 π+nm), and wherein, thickness of detector d=2 π+nm.
Step S203 selects in each response interval, and response speed changes the fastest interval operation interval as phased conversion of a response.
Among Fig. 9, original (0,2 π) phase control range is adjusted to that (m, the interval of 2 π+m) make full use of the fastest response interval of liquid crystal molecule, the i.e. response of approximately linear among figure part.The method should be noted that 2 points:
1, guarantees that the working range of device is more than claimed range;
2, device can not be too thick, otherwise the response speed of device can increase, and this needed at every turn before device is made, and theoretical calculation is the value of m once.
As shown in figure 10, the x axle has been selected the different operating interval, and 0 to 2pi, and 0.1 to 2.1pi, and 0.4 to 2.4pi etc.; The y axle is the response time; Square is represented: in the relevant work interval, and the time that the phased degree of depth of 0.2pi is consumed; Multiplication sign is represented: in the relevant work interval, and the time that the phased degree of depth of 0.8pi is consumed; Triangle is represented: in the relevant work interval, and the time that the phased degree of depth of 1.2pi is consumed; Circle is represented: in the relevant work interval, and the time that the phased degree of depth of 1.6pi is consumed; Asterisk is represented: in the relevant work interval, and the time that the phased degree of depth of 2pi is consumed.As seen, from the operation interval of 0-2pi, must be the slowest interval; As long as revised operation interval is placed on non-0 place, its response speed can greatly increase simultaneously; In the 0.4-2.4pi working range, the response speed in each stage is the fastest.
The method of the embodiment of the invention one and embodiment two can be used within the wavelength coverage of present all silicon-based liquid crystal devices, from visible light to infrared.For the wavelength of different range, the method that can select one of the foregoing description to relate to raises speed separately, also can combine and raise speed; For example, can take embodiment one or two separately, perhaps take two kinds of schemes together device to be quickened simultaneously for visible light and infrared band.
The present invention continues to use the phased LCOS device based on the ECB configuration, because it can satisfy full phase place, debugging continuously; There are not generation (system does not need polarizer), the optical efficiency of other polarized lights to utilize advantages such as maximum (almost 100%) when using mimic channel, extremely low quantize noise, oriented layer angle of inclination very low (maximization phase control range), device work.Therefore this device can be applied to all scopes such as current demonstration, projection, holography, communication.
Although be the example purpose, the preferred embodiments of the present invention are disclosed, it also is possible those skilled in the art will recognize various improvement, increase and replacement, therefore, scope of the present invention should be not limited to the foregoing description.
Claims (11)
1. a method that improves phased silicon-based liquid crystal device response speed is characterized in that, comprising:
Step S101 determines to adjust step-length m;
Step S102 according to the thickness and the working temperature of phased silicon-based liquid crystal device, in conjunction with adjusting step-length m, determines different response intervals;
Step S103 selects the interval interior response speed of each response to change the fastest interval operation interval as phased conversion of a response.
2. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 1 is characterized in that each responds the interval and is respectively: (0,2 π), (m, 2 π+m), (2m, 2 π+2m) ... (nm, 2 π+nm), and wherein, thickness of detector d=2 π+nm.
3. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 1 or 2 is characterized in that, after step S103, also comprises:
Driving voltage is increased to maximum load voltage Vmax, finishes maximum voltage and drive process;
Driving voltage is reduced to the target phase value, i.e. target voltage values Vi; The time that this moment, device needed is t
D_it
D_iBe the response time when from the maximum voltage to the gray shade scale, being i, i=0 wherein, 1,2 ..., 255; Get phase delay to the end.
4. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 3 is characterized in that, before driving voltage being increased to maximum load voltage Vmax, also comprises:
Carry out dc balance and handle, make the alternating electric field symmetry that loads in the silicon-based liquid crystal device on the liquid crystal material.
5. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 4, it is characterized in that, load voltage by maximum load voltage when target voltage values reduces, increase one or more intermediate voltage values, load voltage drops to intermediate voltage value earlier by maximum load voltage, reduces to target voltage values again; Simultaneously, in the waveform forward position of the square wave voltage waveform of driving voltage and back along increasing other predetermined intermediate value, the phase swing when reducing steady state (SS).
6. as the method for claim 4 or the phased silicon-based liquid crystal device response speed of 5 described raisings, it is characterized in that, in the CMOS backboard of silicon-based liquid crystal device, the size of Pixel Dimensions between 1 micron to 20 microns, unit pixel be shaped as rectangle or square.
7. as the method for claim 4 or the phased silicon-based liquid crystal device response speed of 5 described raisings, it is characterized in that the liquid crystal material of silicon-based liquid crystal device is nematic liquid crystalline material, blue phase liquid crystal material or cholesterol liquid crystal material.
8. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 7 is characterized in that the oriented layer of silicon-based liquid crystal device is made up of high molecular polymer, and the friction mode of oriented layer is vertical with the direction vector of liquid crystal molecule; When liquid crystal material was applied in the structure of automatically controlled property birefraction, the initial friction angle of oriented layer was 2 °; When liquid crystal material was applied in the device of optical compensation structure, the initial friction angle of oriented layer was not less than 8 °.
9. as the method for claim 4 or the phased silicon-based liquid crystal device response speed of 5 described raisings, it is characterized in that the driving voltage of silicon-based liquid crystal device is sinusoidal wave pulse, triangular pulse or square-wave pulse.
10. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 8 is characterized in that, the phased LCOS device under mimic channel drives, and maximum voltage is 7V, gray level from 0 to 255.
11. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 8 is characterized in that, maximum load voltage Vmax is that gray-scale value is 255 or 189 pairing load voltage values.
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