Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a driving method of an electrowetting display, which designs an electrowetting driving waveform by using a hysteresis effect in electrowetting characteristics, and can improve electrowetting response time and electrowetting gray scale stability and improve electrowetting display quality compared with the existing electrowetting display.
In a first aspect, an embodiment of the present invention provides: an electrowetting display driving method comprising:
driving the ink in stages through a gray scale driving waveform, wherein the gray scale driving waveform comprises a plurality of sub-frame driving waveforms, and each stage drives the ink through a sub-frame driving waveform to obtain a sub-image frame;
acquiring each sub-image frame;
each sub-picture frame is combined into a complete picture frame.
Further, the gray scale driving waveform includes three sub-driving waveforms, and each sub-driving waveform is driven by a driving voltage.
Furthermore, each driving voltage is a direct current voltage, and the driving time of each driving voltage is the same.
Further, still include:
obtaining a hysteresis curve according to the maximum driving voltage and the initial driving voltage;
if the initial driving voltage is increased to the maximum driving voltage, fitting according to the rising edge of the hysteresis curve to obtain a first response curve;
if the maximum driving voltage is reduced to the initial driving voltage, fitting according to the falling edge of the hysteresis curve to obtain a second response curve;
calculating to obtain a third response curve according to the first response curve and the second response curve;
respectively obtaining driving voltages corresponding to the three sub-driving waveforms according to the first response curve, the second response curve and the third response curve, wherein the driving voltages are respectively: a first drive voltage of the first sub-drive waveform, a second drive voltage of the second sub-drive waveform and a third drive voltage of the third sub-drive waveform
Further, the first driving voltage is obtained by utilizing the first response curve according to the target reflectivity and the allowable jitter range of the reflectivity.
Further, the second driving voltage is smaller than the first driving voltage, and in the process of adjusting the second driving voltage, the reflectivity jitter is within the reflectivity allowable jitter range.
Further, the third driving voltage is a voltage at which the ink is driven to reach a target reflectivity on the third response curve.
The embodiment of the invention at least has the following beneficial effects:
in a second aspect, an embodiment of the present invention provides: an electrowetting display comprising:
driving is performed using the electrowetting display driving method according to any one of the first aspect.
In a third aspect, an embodiment of the present invention provides: an electrowetting display device comprising:
at least one processor; and a memory communicatively coupled to the at least one processor;
wherein the processor is adapted to perform the method of any of the first aspects by invoking a computer program stored in the memory.
In a fourth aspect, an embodiment of the invention provides: a computer-readable storage medium having stored thereon computer-executable instructions for causing a computer to perform the method of any one of the first aspects.
The embodiment of the invention has the beneficial effects that:
the ink is driven in stages through the gray scale driving waveform, wherein the gray scale driving waveform comprises a plurality of sub-frame driving waveforms, each stage drives the ink through one sub-frame driving waveform to obtain one sub-image frame, then the plurality of sub-image frames are obtained, and the plurality of sub-image frames are combined into the complete image frame. The electrowetting driving waveform is designed by utilizing the hysteresis effect in the electrowetting characteristic, and compared with the existing electrowetting display, the response time of the gray scale display of the electrowetting display device can be reduced, the electrowetting response time and the electrowetting gray scale stability are improved, and the electrowetting display quality is improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.
The embodiment of the invention provides a driving method of an electrowetting display, which can be used in the fields of electrowetting displays such as electronic paper displays, electronic books and outdoor advertisement display screens.
The electrowetting refers to a process of changing the wettability of a liquid drop and a solid surface by adjusting a voltage applied between the liquid drop and the solid (for example, an electrode below an insulating medium) in contact with the liquid drop when surface tension dominates force on a millimeter scale, so as to change a three-phase contact angle between the liquid drop and the solid surface, deform the liquid drop, further generate a pressure difference inside the liquid drop, and drive the liquid drop to move.
Fig. 1 is a schematic flow chart of a driving method of an electrowetting display provided in an embodiment of the present invention, and as shown in fig. 1, the driving method includes the following steps:
s1: driving the ink in stages through a gray scale driving waveform, wherein the gray scale driving waveform comprises a plurality of sub-frame driving waveforms, and each stage drives the ink through a sub-frame driving waveform to obtain a sub-image frame;
s2: acquiring a plurality of sub-image frames, wherein the number of the sub-image frames is the same as that of the sub-frame driving waveforms;
s3: the plurality of sub-image frames are combined into a complete image frame.
In one embodiment, the grayscale driving waveform belongs to an amplitude-frequency hybrid modulation algorithm, a complete image frame is divided into a plurality of sub-image frames by using frequency modulation in the amplitude-frequency hybrid modulation process of the electrowetting display for combined display, and the adopted specific grayscale driving waveform is formed by combining sub-frame driving waveforms with the number consistent with that of the sub-image frames, that is, the ink in the electrowetting is subjected to precise grayscale control in stages.
In one embodiment, the grayscale drive waveform includes three sub-frame drive waveforms, respectively: the driving voltage of each sub-frame driving waveform is direct current voltage, and the driving duration is the same.
Wherein, the driving voltage of the first sub-driving waveform is a first driving voltage, denoted as VFThe driving voltage of the second sub-driving waveform is a second driving voltage, denoted as VMThe driving voltage of the third sub-driving waveform is the third driving voltage, and is denoted as VE。
In one embodiment, the three drive voltages are determined by hysteresis curves. The hysteresis curve is a curve generated from the hysteresis effect of electrowetting.
The electrowetting electronic paper controls colored oil drops to move by applying voltage, and gray scale display is further achieved. Along with the increase of the electric field, the surface tension among the insulating layer, the oil film and the water is increased, the contact angle between the interfaces is increased, the electric field force generated by the voltage difference breaks the original balance, and the water replaces the ink to be in contact with the surface of the hydrophobic insulating layer. The ink is pushed to shrink together to expose the white substrate, and the ratio of the area size of the exposed white substrate to the pixel area is the electrowetting reflectivity. The reflectivity is controlled by the driving voltage, and the reflectivity is different under different driving voltages.
Fig. 2 is a schematic diagram of a hysteresis curve of a dc signal driven electrowetting device. As can be seen from the graph, the horizontal axis represents voltage, the vertical axis represents reflectance, and the horizontal axis represents voltageThe response between the reflectivity and the voltage of the pixel in the rise-phase electrowetting device is shown as curve L1In the voltage drop phase, the response relation between the reflectivity and the voltage of the pixel in the electrowetting device is shown as a curve L2Curve L1And curve L2This is, in contrast, a hysteresis effect of electrowetting devices.
In one embodiment, a method of obtaining a hysteresis curve is provided. For example, the step-state driving voltage is stepped from the minimum voltage to the maximum voltage and then from the maximum voltage to the minimum voltage, the reflectivity is measured in real time in the driving process, and the response relation curve between the reflectivity and the voltage is the hysteresis curve.
As shown in fig. 3, a schematic flow chart of calculating the three driving voltages in an embodiment includes the following steps:
s11: obtaining a hysteresis curve according to the maximum driving voltage and the initial driving voltage;
s12: if the initial driving voltage V0Slowly increasing to the maximum driving voltage VMAXFitting according to the rising edge of the hysteresis curve to obtain a first response curve F1(V);
S13: if the maximum driving voltage VMAXDown to the initial driving voltage V0Fitting according to the falling edge of the hysteresis curve to obtain a second response curve F2(V);
S14: according to a first response curve F1(V) and a second response curve F2(V) calculating to obtain a third response curve F3(V);
S15: and respectively obtaining a first driving voltage, a second driving voltage and a third driving voltage according to the first response curve, the second response curve and the third response curve.
Fig. 4 is a schematic diagram of three response curves according to an embodiment. The horizontal axis represents voltage and the vertical axis represents reflectance, wherein R0Indicating the set target reflectivity, RMINDenotes the minimum reflectance, R, of the inkMAXDenotes the maximum reflectance, [ - Δ R,. DELTA.R, of the ink]Indicating a set allowable jitter range of reflectivity, V0Indicating minimum drive of driving inkThe voltage is called initial driving voltage and can be 0V, VMAXRepresents the maximum driving voltage for driving the ink. RMIN、RMAXCan be obtained by measuring the hysteresis curve. It will be appreciated that the reflectivity allowable jitter range may be expressed in other ways, such as 0, 2 Δ R]For example, the present embodiment is not limited thereto.
In one embodiment, step S14 calculates a third response curve F3The procedure (V) is as follows.
Setting a third response curve F3(V) is a quadratic curve, as shown in FIG. 4, two points are selected, the first point being a first response curve F1(V) and a second response curve F2One intersection of (V), denoted as (R)MIN,V0) The second point being a reflectance value of R0At + Δ, the point on the first response curve, denoted as (R)0+Δ,F1 -1(R0+ Δ)), while setting the second point as the vertex of the quadratic curve, a third response curve F is calculated3(V)。
After the three response curves are obtained, a first driving voltage V is obtained through calculationFA second driving voltage VMAnd a third driving voltage VE。
In one embodiment, the reflectance R is based on a target reflectance0And the allowable jitter range of reflectivity [ - Δ R, Δ R]Using the first response curve F1(V) obtaining a first drive voltage V of a first sub-drive waveformFExpressed as:
F1(VF)=R0+ΔR
i.e. can pass the first response curve F1(V) obtaining a first driving voltage V of the first sub-driving waveformF。
In one embodiment, the second driving voltage V of the second sub-driving waveformMIs less than the first drive voltage VFAnd adjusting the second driving voltage VFIn the process, the reflectivity jitter Δ R' is within the reflectivity allowable jitter range [ - Δ R, Δ R [ ]]And (c) internally, namely, the conditions are met:
therefore, the second driving voltage V of the present embodimentFCan be dynamically changed by only meeting the conditions.
In one embodiment, the third driving voltage V of the third sub-driving waveformETo drive the ink in the third response curve F3(V) achieving a target reflectance R0The voltage of time. For example, target reflectivity R0Substituting into the third response curve F3(V) obtaining a third driving voltage VEI.e. R0=F3(VE)。
As shown in fig. 5, which is a schematic diagram of driving voltages in an embodiment, the driving durations of the three sub-frame driving waveforms are all set to be the same due to the active matrix, and the first driving voltage V is set to be the sameFIs [0, t), the second drive voltage VMIs [ t, 2t ]), and the third driving voltage VEHas a driving duration of [2t, 3t ]]And a complete gray scale driving waveform is formed to drive the ink.
It can be understood that the second driving voltage VMMay be greater than the third driving voltage VEOr when the second driving voltage V is satisfiedMUnder the condition of (1), the second drive voltage VMOr less than the third driving voltage VE。
As can be seen in FIG. 5, the drive durations are all t, and the ink is being applied with the first drive voltage VFAfter time t, the light beam is pushed to one side of the pixel wall, the surface energy of the light beam is reduced, the kinetic energy of the light beam is increased, and the reflectivity is gradually increased from 0 to R0+ Δ R; then when the applied voltage is reduced to a second driving voltage VMMeanwhile, the electric field force is not enough to maintain the state of the ink, the ink impacts the contact surface through the increased kinetic energy, the balance between the surface energy and the kinetic energy is achieved again through the ink at the moment t, and then the second driving voltage V is usedMThe generated electric field force pushes the ink to move, and the reflectivity is jittered, but the jittering amplitude is jitteredWithin the range of reflectivity allowable jitter [ - Δ R, Δ R]Internal; reducing the driving voltage to a third driving voltage V until the time of 2tEThe ink reaches the balance between the interface energy and the kinetic energy again, the reflectivity gradually tends to be stable, and the driving system drives the voltage V at the stable voltageEAnd the violent oscillation of the pixel caused by PWM modulation is reduced.
The three driving voltages are respectively acted on the 3 sub-image frames, and then the sub-image frames are combined to obtain a complete image frame, so that the response time of pixels can be shortened, and the display quality is improved.
The response time of the electrowetting display device is the speed of the electrowetting display device in the switching process, the electrowetting display is realized by the movement of the ink, the movement speed of the ink is asynchronous with the application control model, and the occurring delay is the response time. The present embodiment can accelerate the response time of the electrowetting display device.
In one embodiment, the method of the present embodiment shortens the response time by 70% compared to the conventional dc driving, and effectively improves the display quality of the electrowetting display device, so that the gray scale display is more stable, and the gray scale oscillation can be effectively reduced by 80% compared to the conventional square wave driving.
An embodiment of the invention further provides an electrowetting display, which is driven by using the electrowetting display driving method according to any one of the above embodiments, and the specific details are described in detail in the electrowetting display driving method corresponding to the above embodiment, and therefore are not described herein again.
In addition, the present invention also provides an electrowetting display device comprising:
at least one processor, and a memory communicatively coupled to the at least one processor;
wherein the processor is configured to perform the method according to embodiment one by calling the computer program stored in the memory. A computer program, i.e. a program code, for causing an electrowetting display device to perform the steps in the method for driving an electrowetting display as described in the previous section of the embodiments of the specification, when the program code is run on the electrowetting display device.
In addition, the present invention also provides a computer-readable storage medium, which stores computer-executable instructions for causing a computer to perform the method according to embodiment one.
Without loss of generality, the computer-readable media may comprise computer storage media and communication media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory technology, CD-ROM, DVD, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices. Of course, those skilled in the art will appreciate that the computer storage media is not limited to the foregoing.
It should be noted that: the sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. And specific embodiments thereof have been described above. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the electrowetting display, the electrowetting display device and the computer readable storage medium embodiment, since they are substantially similar to the method embodiment, the description is relatively simple, and in relation thereto, reference may be made to the partial description of the method embodiment.
The above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same, although the present invention is described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.