CN103197455B - Method for increasing responding speed of phase only liquid crystal on silicon device - Google Patents
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Abstract
The invention discloses a method for increasing the responding speed of a phase only liquid crystal on silicon (LCOS) device. The method comprises the following steps: S101, increasing the driving voltage to the maximum load voltage Vmax and finishing the maximum voltage driving process; S102, reducing the driving voltage to the target voltage value Vi determined by the working temperature of the device to realize the expectant target phase value, wherein the required time of the device at the moment is td_i, the td_i is the responding time from the maximum voltage to the gray scale i, and the i=0, 1, 2, ..., 255; and S103, obtaining the final phase delay. The method adopts an electrically controlled birefringence (ECB) mode to fulfill the aim of increasing the speed of the device on the basis of meeting the original advantages of continuous phase debugging, extremely low quantized error, high optical transmission efficiency, all phase debugging and the like.
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 is developing aspect image and 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 electric signal to control the deflection of liquid crystal material, in the process of this variation, incident light is carried out to full phase place, continuous debugging, from principle, utilization ratio for light is best.Therefore the application function of this device has enriched again many than traditional LCD demonstration and the demonstration of LCOS image.At present at aspects such as optical communication, line holographic projections, occupy certain advantage.
The LCOS device probably is divided into two classes: the first kind is debugged the amplitude of light, i.e. above-mentioned traditional LC OS display device; Equations of The Second Kind is only debugged the phase place of light.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 modulation changes the birefraction of liquid crystal molecule by the electric signal be carried on cmos circuit, thereby reaches the effect that postpones the incident light phase place,
Because the birefraction variation range of liquid crystal material is larger, therefore in phased LCOS device, usually use liquid crystal material as the light transmission medium.In the middle of the LCOS device at phase modulation, polaroid and other optical device do not have light absorption, and 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 from " sandwich " structure of traditional LC D device, one deck glass substrate wherein changed into to the silicon substrate of CMOS integrated circuit, 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 occurs in incident light in the process of liquid crystal deflecting element.
Liquid crystal material is a kind of state of matter be situated between between solid and liquid.The state of liquid crystal material is divided into again the nematic crystal state, smectic crystal state (Smectic Phase) etc.As a rule liquid crystal state is distinguished in the orientation in space by molecule, and the molecule center of gravity is in the distribution in space.Such as the molecule of nematic crystal is long thin excellent type, the distribution of their molecule is to point to certain direction.Due to liquid crystal molecule, at high temperature, be the form with liquid, i.e. (the Isotropic Phase) of any direction state, thus to keep certain specific direction attribute of liquid crystal, within environment temperature need to being remained on to a scope.
As shown in Figure 2, take nematic liquid crystalline material as example, it is one of common liquid crystal state, and its molecule is that bar-shaped, its arrangement has certain orientation.Main photoelectric material in 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 that continuous phase is debugged, by increasing silicon-based liquid crystal device (LCOS), adopted 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 be applied in this device must meet 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 specific inductive capacity, K
iithe elasticity coefficient of liquid crystal material, τ
risingand τ
decayit is rise response time and decline response time.Derive thickness in formula and speed is directly proportional.
2, high-k (threshold voltage is low):
By publicity 1 and 2, drawn, specific inductive capacity and speed are inversely proportional to.
3, this material require can 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 large impact for the application in optical communication system, therefore is chosen in the stable liquid crystal of communication C-band (1530-1565nm) most important.
Electrically conerolled birefringence rate (ECB, Electrically Controlled Birefringence) the LCOS device principle of work of configuration as shown in Figure 3, when there is no voltage-drop loading in device ("off" state), liquid crystal molecule is arranged according to the direction of oriented layer, now n
obe parallel to Z axis, n
ebe parallel to Y-axis.When analog voltage loads on device (" conducting " state), along with the increase gradually of analog voltage, n
odirection is constant still is parallel to Z axis, and n
egradually by parallel Y-axis to parallel Z axis, the liquid crystal molecule in Fig. 3 " is stood " gradually, now the n in process
enumerical value to n
onumerical value convergence (birefraction maximum again levels off to 0), until the maximum analog voltage loads is when the device, two values equate, complete the deflection of liquid crystal molecule with voltage, incident light phase modulation process finishes.Because the polarized light that there is no other directions in this process produces, 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 experiencing, i.e. the incident light time that phase place from 0 to 2 π consumes after the debugging of LCOS device.
The response time of device is under the mode of operation of ECB, and, in visible ray and infrared scope, utilizes the loading of binary raster, drives each voltage level to realize simultaneously.By measuring light intensity and the relation of response time, derive phase place variation and the relation of time response.This essential information will be brought huge facility to the holographic designs slip-stick artist, understand each pixel in the situation that drives different voltages, accurately locate the phase place pace of change.
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 at present LCOS response device speed is mainly the configuration that changes device architecture and liquid crystal material.The ferroelectric liquid crystals Surface Stablised Ferroelectric Liquid Crystal(SSFLC that more representational two kinds of modes are surface-stable patterns) and the birefraction pattern Optically Compensated Birefringence(OCB of optical compensation).
Application SSFLC LCOS device, because its response speed and without add the advantage of polarizer in system fast has 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 at gamut (between 0 to 2 π) and continuous phase modulation.Although sequence of subframes (Subframe Sequential) technology can provide multivoltage and many grades phase modulation, and applies 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 to configure very special ferroelectric material and just can reach in certain thickness device, and response speed now 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 modulation, 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 contrary 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, in the OCB device, the angle of inclination of oriented layer is generally more than 8 °, and liquid crystal molecule can only be in the lower work of Bending Deformation (Bend Deformation).Although the response speed of OCB device is very fast, it has following three kinds of fatal defects: 1, scope less than 2 π of its phase modulation.General in the LCOS of ECB structure device, the angle of inclination of oriented layer within 2 °, the phase modulation 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 affects the phase modulation scope; 2, device in working order in, liquid crystal molecule can produce distortion state (Twist State), this will cause, in the incident light debug process, producing the light of various polarization directions, thereby reduce the light debugging efficiency of device; 3, the friction process that the high dip angle of oriented layer is configured to oriented layer has brought huge difficulty, in the technological process of its hot setting, can cause the unstable of pixel aluminium lamination, destroys the reflectivity on pixel top layer.
Summary of the invention
The technical problem to be solved in the present invention is to provide 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 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, determine and adjust step-length m;
Step S102, according to thickness and the working temperature of phased silicon-based liquid crystal device, in conjunction with adjusting step-length m, determine different response intervals;
Step S103, select the interval interior response speed of each response to change the fastest interval operation interval as phased conversion of a response.
Further, each responds interval and is respectively: (0,2 π), and (m, 2 π+m), (2m, 2 π+2m) ..., (nm, 2 π+nm), wherein, thickness of detector d=2 π+nm.
Further, after step S103, also comprise:
Driving voltage is increased to maximum load voltage Vmax, completes maximum voltage and drive process;
Driving voltage is down to the target phase value, i.e. target voltage values Vi; The time that now device needs is t
d_i; t
d_ithe response time while from the maximum voltage to the gray shade scale, being i, i=0 wherein, 1,2 ..., 255;
Obtain last phase delay.
Further, before driving voltage being increased to maximum load voltage Vmax, also comprise:
Carry out the DC balance processing, make in silicon-based liquid crystal device to load on the alternating electric field symmetry on liquid crystal material.
Further, when load voltage is reduced to target voltage values by maximum load voltage, increase one or more intermediate voltage values, load voltage first drops to intermediate voltage value by maximum load voltage, then is down to target voltage values; Simultaneously, in the waveform forward position of the square wave voltage waveform of driving voltage and rear along increasing other predetermined intermediate value, the phase swing while 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 comprised 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 is applied in the structure of automatically controlled property birefraction, the initial friction angle of oriented layer is 2 °; When liquid crystal material is applied in the device of optical compensation structure, the initial friction angle of oriented layer is 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 corresponding load voltage values.
Beneficial effect of the present invention is as follows:
The present invention adopts ecb mode, is meeting on the former bases that have superiority such as continuous phase debugging, extremely low quantized error, high light transmissioning efficiency, full phase modulation, has reached the purpose of device speed-raising.
The accompanying drawing explanation
Fig. 1 is the basic block diagram of LCOS in prior art;
Fig. 2 is the single shaft light index map of single liquid crystal molecule refractive index in prior art;
Fig. 3 is the LCOS device work schematic diagram of electrically conerolled birefringence rate configuration in prior art;
Fig. 4 is the response time schematic diagram that adopts prior art;
Fig. 5 is the response time schematic diagram that adopts embodiment of the present invention scheme;
Fig. 6 is response time of adopting respectively prior art and embodiment of the present invention scheme to obtain and the comparison diagram of phase control range;
Fig. 7 is the comparison diagram of embodiment of the present invention medium-high frequency component in analogy and digital circuit;
Fig. 8 is the comparison diagram of different loads lower response time of voltage and the phased degree of depth in the embodiment of the present invention;
Fig. 9 is the graph of a relation that in the embodiment of the present invention, driving voltage and phase modulation change;
Figure 10 is response intervals different in the embodiment of the present 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 voltage improves, and the phase modulation degree of depth increases.The inventor, through great many of experiments, finds that the response time of liquid crystal material is to reduce according to the raising of load voltage, improves the response that voltage loads can be accelerated device, and the load that reduces voltage has slowed down the response of device.That is: in the situation that load voltage is greater than threshold voltage, if load voltage is improved, the response of liquid crystal material will be accelerated; This relation is monotonically increasing.Therefore, prior art is debugged little phase place while changing at device, and the voltage required due to device is very low, so that response speed becomes is very slow.The present invention, according to the relation of load voltage and response time, has solved the phased silicon-based liquid crystal device of current main flow and has produced the excessively slow problem of response speed by its type of drive, reaches the effect of response device speed-raising.The accelerating method adopted at present is mainly to select to be attempted at change device architecture and liquid crystal, and two kinds of methods (SSFLC and OCB) of main flow have huge defect; And the present invention is adhering to adopting ecb mode, the liquid crystal molecule that collocation satisfies condition, meeting on the former bases that have superiority such as continuous phase debugging, extremely low quantized error, high light transmissioning efficiency, full phase modulation, change by the following method cmos circuit 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 experiencing from 0.In the LCOS of phase modulation device, be defined as the light intensity of first-order diffraction from 0 time of experiencing to maximum.Because the grating information loaded is that voltage by driving element completes, so the relation of the variation of diffraction intensity and load voltage can change by mathematics, is derived as the relation of phase delay and time.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 of phase modulation device, the embodiment of the present invention changed for the time in 5% to 95% diffracted ray strength range, can record so more phase modulation information, and the raising of response speed is had to judgement more accurately.Rise time response is when voltage rises to target voltage numerical value from 0 voltage, the needed time of device; Refer to when voltage is down to 0 voltage from target voltage the time that device needs fall time.In the situation that load voltage is greater than threshold voltage, if load voltage is improved, the corresponding speed of liquid crystal material will be accelerated, and this relation is monotonically increasing.
Embodiment mono-:
The embodiment of the present invention relates to a kind of method that improves phased silicon-based liquid crystal device response speed: comprising:
Step S101, be increased to maximum load voltage Vmax to driving voltage, completes maximum voltage and drive process;
In this step, the phased LCOS device under mimic channel drives, maximum voltage is generally in 7V left and right, 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.According to epimere, describe, the trivial response time of supposing device should be t
i, i.e. response time when load voltage gray shade scale (N) is i.Current type of drive, in debugging full phase place (2 π) numerical value, response device is fastest, 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 while first loading " debugging full phase place " numerical value, and then voltage corresponding to select target phase place, realize device speed-raising process.
The required fastest response speed of device is t
n=t
255; Through experiment measuring fastest response speed result, be t
n=t
255=7ms.
In silicon-based liquid crystal device, liquid crystal layer is clipped between electrode ITO layer and aluminium lamination; Due to the work function difference of this bi-material, when symmetrical alternating voltage loads on liquid crystal layer by such asymmetric electrode, its actual on-load voltage is equivalent to former on-load voltage and has added a direct current (DC) bias, and liquid crystal material can't enter a stable state.Therefore, for obtaining better technique effect, this step also needs to carry out DC balance (DCbalance), by the alternating electric field symmetrization loaded in silicon-based liquid crystal device on liquid crystal material.If do not carry out DC balance, the phenomenon of phase swing can be fairly obvious, causes the hydraulic performance decline of device.
Step S102, be down to the target voltage values Vi definite according to the device working temperature by driving voltage, realizes the set goal phase value; The time that now device needs is t
d_i; t
d_ithe response time while from the maximum voltage to the gray shade scale, being i, i=0 wherein, 1,2 ..., 255;
Rotator inertia due to the continuous variation characteristic of the phase place of liquid crystal material and liquid crystal molecule, and between interaction, after on-load voltage changes, liquid crystal material can produce in various degree " flyback " (flyback), causes corresponding phase swing (phase flicker).Therefore, in the present embodiment, when load voltage is reduced to target voltage values by maximum load voltage, 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 rear along increasing other predetermined intermediate value, to slow down " flyback ", the phase swing while reducing steady state (SS).
Step S103, obtain last phase delay.
The device load voltage is from 0 voltage to V
ineeded process is 0, Vmax, V
i; Total response time t
ifor:
T
i=t
255+ t
d_iformula 3
Wherein, t
255it is the response time that gray scale is 255 o'clock (maximum voltage).
In the present embodiment, in the time of in the scope of silicon-based liquid crystal device temperature at [15 °, 55 °], along with the rising of temperature, the response speed of silicon-based liquid crystal device can be more and more faster.
In Fig. 4 at voltage V
idrive the response time t of lower device
i(adopt prior art, by loaded targets voltage, after waiting for liquid crystal response, obtain phase delay); Be according to accelerating method in Fig. 5, first voltage be arranged to 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), obtain last phase delay; Apply this kind of method at V
iresponse time t under voltage
iequal t
255with t
d_isum.According to after actual computation, show that the speed-raising scheme is feasible and effective.
It is to be noted: as i=189 or when above, t
iresponse time do not need through having raised speed.Phase modulation scope now is 1.96 π, approximate full phase place the debugging scope 98%, in the situation that consider error, this has guaranteed the integrality of device work fully.This has proved under the condition that does not affect the device serviceability, and the speed-raising that realizes the response time is feasible.In practical application, need to load the driving voltage of a maximum to picture element matrix before the concrete image information of scanning, then load the needed voltage of picture element matrix and get final product.Apply this kind of type of drive, likely 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 corresponding 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.
In Fig. 6, open circle means according to existing type of drive, and voltage rises to the phase control range of target target voltage from original 0 voltage; Solid rim means to adopt the scheme of the embodiment of the present invention, and voltage is first maximum voltage from 0 voltage-drop loading, and then is down to the phase control range of target voltage; As can be seen from Figure 6, the speed-raising scheme of the embodiment of the present invention raises speed obviously on this device, and during 189 gray level, device has completed whole phase control ranges substantially.While changing as little phase place, the 100ms rank that can raise speed (phase modulation<1 π), all the other tens ms(1 π that substantially can raise speed, 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 rectangle or foursquare.The thickness of silicon-based liquid crystal device is generally between 1 micron to 5,6 microns; Take wavelength as benchmark, and wavelength is longer, and thickness of detector is larger, and thickness meets 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), can be also 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 comprised 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 it is 2 ° of left and right; If liquid crystal material is applied in the device of optical compensation structure, the initial angle of oriented layer generally can not 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, can be also foursquare, and the shape of pixel layer can be rectangle or foursquare, under 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, can be also triangular pulse or square-wave pulse.ITO(Indium Tin Oxide, indium tin oxide) electrode can be dot matrix (corresponding each pixel), can be also to cover glass substrate.
In addition, in above-described embodiment, can also be increased in the process of maximum load voltage Vmax at load voltage, load voltage is stopped to target voltage values, obtain last phase delay.That is: these pulses in certain time interval, load the pulse of a series of maximum voltages, before should load on required pulse voltage.
Because the response device time is the shortest when maximum voltage drives, and the phase place variation can reach 2 π.Therefore analyze theoretically, in the process that loads excessive driving voltage, can select the middle corresponding magnitude of voltage of phase depth arbitrarily of from 0 to 2 π, thereby realize the quick response of device.But while in side circuit drives, applying this kind of method, the requirement that tends to exceed target phase.However, we still can utilize this principle in actual circuit 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, while 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 arbitrarily waveform, in this case, the method for response time speed-raising should not be used.If but when comprising the component of low frequency and the response speed of liquid crystal material molecules, waveform is similar to, and liquid crystal material so now is according to the instantaneous value response of waveform, and " excessive " voltage drives and can realize in this case.
In high frequency analog circuits, liquid crystal can't corresponding high fdrequency component, if in Fig. 7, a figure equates with the area of shade in b figure, and they are equivalent for the driving of liquid crystal molecule so; Situation in high frequency digital circuits is the same with the situation in high frequency analog circuits, as long as c figure is identical with the area of shade in d figure, their driving is equivalent.But, in low frequency simulation or digital circuit, the response of liquid crystal molecule is relevant to independent component of voltage.
In Fig. 8, X-axis (Time) the expression time; Y-axis (Phase Modulation) means the phased degree of depth.Lines near X-axis in Fig. 8 mean: when load is 4.4v, the scope of phase modulation, between (0,1.93 π), can't reach full phase modulation, and needing the time is to complete within 21.2ms.Lines in the middle of in Fig. 8 mean: when load is 5.7v, the phase modulation scope meets full phase modulation substantially, and needing the time is 9.7ms.In Fig. 8, the lines of close Y-axis mean, when load is maximum 7v, the phase modulation model meets full phase modulation, need the time only within 4.6ms.By this experimental result, can be found out: 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 modulation of needs 1 π, while adopting so load 7v, the speed needed is the 2.3ms left and right.
Embodiment bis-:
Consider error and the 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 manufacture thickness of device is often a little more than requirements; Be generally 2.5 π, even 3 π.So both guarantee the serviceability of device, and can make again full phase modulation scope more flexible.According to these characteristics, in the embodiment of the present invention, revised the interval of working range, original (0,2 π) is moved to (m, 2 π+m), wherein, m adjusts step-length.The purpose of doing like this, improve the slow response of low-voltage, keeps working range constant simultaneously.
The embodiment of the present invention relates to a kind of method that improves phased silicon-based liquid crystal device response speed: comprising:
Step S201, determine and adjust step-length m; Adjusting step-length m can be fixed numbers, can be also different numerical value, specifically determines method, by the technician, according to device characteristics, is determined.
Step S202, according to the thickness of phased silicon-based liquid crystal device, in conjunction with adjusting step-length m, determine different response intervals, for example, and (0,2 π), (m, 2 π+m), (2m, 2 π+2m) ..., (nm, 2 π+nm), wherein, thickness of detector d=2 π+nm.
Step S203, select in each response interval, and response speed changes the fastest interval operation interval as phased conversion of a response.
In Fig. 9, original (0,2 π) phase control range is adjusted to (m, 2 π+m) interval, takes full advantage of the fastest response interval of liquid crystal molecule, i.e. the response of approximately linear in figure part.The method should be noted that 2 points:
1, guarantee 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 manufactured, 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 means: in the relevant work interval, and the time that the phased degree of depth of 0.2pi consumes; Multiplication sign means: in the relevant work interval, and the time that the phased degree of depth of 0.8pi consumes; Triangle means: in the relevant work interval, and the time that the phased degree of depth of 1.2pi consumes; Circle means: in the relevant work interval, and the time that the phased degree of depth of 1.6pi consumes; Asterisk means: in the relevant work interval, and the time that the phased degree of depth of 2pi consumes.Visible, from the operation interval of 0-2pi, must be for the slowest interval; As long as revised operation interval is placed on to non-zero 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.
Within the method for the embodiment of the present invention one and embodiment bis-can be used in the wavelength coverage of current all silicon-based liquid crystal devices, from visible ray to infrared.For the wavelength of different range, the method that can select one of above-described embodiment to relate to is raised speed separately, also can combine and be raised speed; For example, can take separately embodiment mono-or two for visible ray and infrared band, or take two schemes together device to be accelerated simultaneously.
The present invention continues to use the phased LCOS device based on the ECB configuration, because it can meet full phase place, debugging continuously; While using mimic channel, extremely low quantize noise, oriented layer angle of inclination very low (maximization phase control range), device work, do not have generation (system does not need polarizer), the optical efficiency of other polarized lights to utilize advantages such as maximum (almost 100%).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 is also possible those skilled in the art will recognize various improvement, increase and replacement, therefore, scope of the present invention should be not limited to above-described embodiment.
Claims (7)
1. a method that improves phased silicon-based liquid crystal device response speed, is characterized in that, comprising:
Step S101, be increased to maximum load voltage Vmax to driving voltage, completes maximum load voltage and drive process; Phased silicon-based liquid crystal device under mimic channel drives, maximum load voltage is 7V;
Step S102, be down to the target voltage values Vi definite according to the device working temperature by driving voltage, realizes the set goal phase value; The time that now device needs is td_i; Td_i is the response time while being target voltage values Vi corresponding to i from maximum load voltage to gray-scale value, i=0 wherein, and 1,2 ..., 255; When driving voltage is reduced to target voltage values by maximum load voltage, increase one or more intermediate voltage values, driving voltage first drops to intermediate voltage value by maximum load voltage, then is down to target voltage values; Simultaneously, in the waveform forward position of the square wave voltage waveform of driving voltage and rear along increasing other predetermined intermediate value, the phase swing while reducing steady state (SS);
Step S103, obtain last phase delay.
2. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 1, is characterized in that, maximum load voltage Vmax is that gray-scale value is 255 corresponding driving voltage values.
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, before step S101, also comprises:
Carry out the DC balance processing, make in phased silicon-based liquid crystal device to load on the alternating electric field symmetry on liquid crystal material.
4. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 1, is characterized in that, before step S101 or after step S103, also comprises:
Determine and adjust step-length m;
According to the thickness of phased silicon-based liquid crystal device, in conjunction with adjusting step-length m, determine different response intervals;
Select in each response interval, response speed changes the fastest interval operation interval as phased conversion of a response.
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, in the CMOS backboard of phased silicon-based liquid crystal device, the size of Pixel Dimensions between 1 micron to 20 microns, unit pixel be shaped as rectangle or square.
6. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 4, is characterized in that, the liquid crystal material of phased silicon-based liquid crystal device is nematic liquid crystalline material, blue phase liquid crystal material or cholesterol liquid crystal material.
7. the method for the phased silicon-based liquid crystal device response speed of raising as claimed in claim 6, is characterized in that, the oriented layer of phased silicon-based liquid crystal device is comprised 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 is applied in the structure of automatically controlled property birefraction, the initial friction angle of oriented layer is 2 °; When liquid crystal material is applied in the device of optical compensation structure, the initial friction angle of oriented layer is not less than 8 °.
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