Patent Publication Number: US-10784570-B2

Title: Liquid-crystal antenna device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Applications No. 62/523,336 filed on Jun. 22, 2017, and the entirety of which is incorporated by reference herein. 
     This application claims priority of China Patent Application No. 201711159864.8 filed on Nov. 20, 2017, and the entirety of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     Technical Field 
     The disclosure relates to a liquid-crystal antenna device, and in particular to a liquid-crystal antenna device whose voltage signal received by a radiation unit is corrected. 
     Description of the Related Art 
     In a liquid-crystal antenna unit, different dielectric coefficients are generated by controlling the direction of rotation of a liquid crystal via an electric field due to the bi-dielectric coefficient characteristic of the liquid crystal. 
     In the liquid-crystal antenna unit array, by using the electric signal to control the arrangement of the liquid-crystal in each liquid-crystal antenna unit to change the dielectric coefficient of each unit in the microwave system, this can be used to control the phase or the amplitude of the microwave signal in the antenna unit. The liquid-crystal antenna unit array radiates electromagnetic waves toward a predetermined direction after collocation. 
     The microwave signals can be searched for and the angle for receiving and emitting radiation can be adjusted with the signal source to enhance the communication quality by controlling the liquid-crystal antenna unit array. The signal sources may be space satellites, terrestrial base stations, or other signal sources. 
     Wireless communication of liquid-crystal antenna can be used in a variety of vehicles, such as aircrafts, yacht boats, trains, cars and motorcycles, etc., or the Internet of Things, autonomous driving, and unmanned vehicles, etc. Comparing to conventional mechanical liquid-crystal antenna, the electronic one has some advantages such as flat, thin and light, and fast response, etc. 
     However, a liquid-crystal antenna is made of a plurality of radiation units, and the process uniformity of each radiation unit is still poor, which results in a distortion of the output electromagnetic wave. Therefore, there is a need to provide improvement solutions for a liquid-crystal antenna. 
     SUMMARY 
     The present disclosure provides a liquid-crystal antenna device, including: a signal source, providing an input electromagnetic wave, a driving module, outputting a plurality of initial voltage signals according to a radiation address, a correction module, receiving the initial voltage signals and outputting a plurality of corrected voltage signals according to a lookup table, and a plurality of radiation units, receiving the corrected voltage signals and coupling with the input electromagnetic wave to generate an output electromagnetic wave. 
     The present disclosure provides a liquid-crystal antenna device, including: a plurality of radiation units, emitting or receiving an electromagnetic wave, wherein the radiation units include a first radiation unit, a driving module, outputting a plurality of initial voltage signals according to a radiation address, wherein the initial voltage signals include a first voltage signal corresponding to the first radiation unit, and a correction module, receiving the initial voltage signals and outputting a plurality of corrected voltage signals to the radiation units, and wherein the corrected voltage signals include a second voltage signal corresponding to the first radiation unit, wherein the first voltage signal is different from the second voltage signal. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic view of a liquid-crystal antenna device of an embodiment of the present disclosure. 
         FIG. 2  is a schematic perspective view of the liquid-crystal antenna device of  FIG. 1 . 
         FIG. 3  is a top view of the radiation unit in  FIG. 2 . 
         FIG. 4  is a cross-sectional view along line B-B′ in  FIG. 3 . 
         FIG. 5A  is a graph illustrating a relationship between voltage and capacitance of the radiation unit in  FIG. 1  in the ideal state. 
         FIG. 5B  is a graph illustrating a relationship between voltage and capacitance of the radiation unit in  FIG. 1  in the practical state. 
         FIG. 6A  is an equivalent circuit diagram of an integrator for measuring a capacitance of a radiation unit of an embodiment of the present disclosure. 
         FIG. 6B  is an equivalent circuit diagram of  FIG. 6A  after connecting to a test capacitance. 
         FIGS. 7A-7C  are equivalent circuit diagrams of the radiation unit of  FIG. 1  at different voltages. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the subject matter provided. Specific examples of components and arrangements are described below to simplify the present disclosure. These are merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. 
     In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     The terms such as the first and the second in the present disclosure are merely for clarity and are not intended to correspond to or limit the scope of the patent. In addition, the terms such as the first feature and the second feature are not limited to the same or different features. 
     Spatially relative terms, such as “below” or “above,” and the like, are merely used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For clarity, the description of the first feature disposed on the second feature or the lower means that the first feature is on or under the second feature in the stacking direction of the figures in the present disclosure. 
     The shape, size, and thickness in the drawings may not be drawn to scale or simplified for clarity of discussion; rather, these drawings are merely intended for illustration. 
       FIG. 1  is a diagrammatic view of a liquid-crystal antenna device  1  of an embodiment of the present disclosure. A liquid-crystal antenna device  1  can be used to emit an electromagnetic wave signal, which includes a memory unit  10 , a signal source  20 , and a plurality of radiation units RU 1 , RU 2  . . . RUn. The memory unit  10  includes a driving module  11  and a correction module  12 , wherein the driving module  11  according to a radiation address outputs a plurality of initial voltage signals S 1 , S 2  . . . Sn, the correction module  12  receives the initial voltage signals S 1 , S 2  . . . Sn and then outputs a plurality of corrected voltage signals S 1 ′, S 2 ′ Sn′, and the radiation units RU 1 , RU 2  . . . RUn receive the corrected voltage signals S 1 ′, S 2 ′ . . . Sn′ and are coupled to an input electromagnetic wave provided by the signal source  20  to generate an output electromagnetic wave W, and emit the output electromagnetic wave W to the radiation address. In the embodiment, the correction module  12  outputs the corrected voltage signals S 1 ′, S 2 ′ . . . Sn′ according to a lookup table  121 , but are not limited thereto. In the embodiment, the radiation address is defined by the zenith angle θ and the azimuth angle φ of a Spherical coordinate system. And, at least one of the plurality of initial voltage signals is different from at least one of the plurality of corrected voltage signals. 
     The liquid-crystal antenna device  1  mentioned above outputs a plurality of the corrected voltage signals S 1 ′, S 2 ′ . . . Sn′ to the radiation units RU 1 , RU 2  . . . RUn through the correction module  12  in order to adjust the liquid-crystal capacitance value of the radiation units RU 1 , RU 2  . . . RUn to control the resonance frequency of the liquid-crystal antenna device  1 . When the resonance frequency of the liquid-crystal antenna device  1  matches the frequency of the input electromagnetic wave provided by the signal source  20 , the liquid-crystal antenna device  1  will emit the electromagnetic wave W to the radiation address. 
       FIG. 2  is a schematic perspective view of the liquid-crystal antenna device  1  of  FIG. 1 . The liquid-crystal antenna device  1  includes a plurality of arrayed radiation units RU (including the aforementioned radiation units RU 1 , RU 2 , . . . , RUn) and a waveguide WG, wherein the arrangement of a plurality of arrayed radiation units RU may vary by design, and are not intended to be limited. After correction by the aforementioned correction mechanism, the phase difference and the amplitude of the electromagnetic wave emitting into space may be controlled by each radiation unit RU so as to stack and form the electromagnetic wave W. The waveguide WG transmits the electromagnetic wave from the signal source  20  to the radiation units RU. 
     Referring to  FIG. 3  and  FIG. 4 ,  FIG. 3  is a top view showing one of the radiation units in  FIG. 2 , and  FIG. 4  is a cross-sectional view along line B-B′ in  FIG. 3 . The radiation unit RU includes a common electrode  31 , a pixel electrode  32 , and a thing film transistor TFT. The common electrode  31  and the pixel electrode  32  are disposed respectively on a first substrate SUB 1  and a second substrate SUB 2 , and the thin film transistor TFT electrically connects to the common electrode  31  and the pixel electrode  32  respectively, wherein the thin film transistor TFT may be used to transmit the aforementioned corrected voltage signals to the pixel electrode  32 . In another embodiment, the thin film transistor TFT electrically connects to the pixel electrode  32 , and a common voltage source electrically connects to the common electrode  31 . The common electrode  31  and the pixel electrode  32  may be a metal thin layer, which may be made of or include copper, silver, gold, aluminum, any suitable materials or a combination alloy thereof. The common electrode  31  and the pixel electrode  32  may also be a transparent conductive thin layer, which may be made of or include indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc aluminum oxide (IGZAO), any suitable transparent conductor or a combination thereof. The common electrode  31  and the pixel electrode  32  may be any suitable conductor and are not limited thereto, wherein the common electrode  31  is formed with a slit  311 , so that the electromagnetic wave transmitting in the waveguide (not shown) under the common electrode  31  may be radiated to the liquid-crystal layer LC between the common electrode  31  and the pixel electrode  32 . In some embodiments, the pixel electrode  32  overlaps the slit  311 . 
     The first substrate SUB 1  and the second substrate SUB 2  may be made of or include quartz, glass, wafer, metal foil, polymethylmethacrylate (PMMA), polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN), but are not limited thereto, and any material applicable for the first substrate SUB 1  and the second substrate SUB 2  may be used. Liquid-crystal layer LC may include a plurality of liquid-crystal molecules. 
     Still referring to  FIG. 3  and  FIG. 4 , assuming that every radiation unit RU has the same size, the liquid-crystal capacitance of every radiation unit RU can be regarded as an ideal capacitance. The Equation 1 below can be simplified as a function of voltage when the size of the ideal capacitance is fixed, which means that all of the radiation units RU can have a consistent liquid-crystal capacitance C LC  via an initial voltage-capacitance curve C initial  (as shown in  FIG. 5 ) when inputting a specific voltage value: 
     
       
         
           
             
               
                 
                   
                     C 
                     LC 
                   
                   = 
                   
                     
                       
                         ɛ 
                         LC 
                       
                       ⁡ 
                       
                         ( 
                         V 
                         ) 
                       
                     
                     ⁢ 
                     
                       A 
                       d 
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   ) 
                 
               
             
           
         
       
     
     Here, ε LC (V) is a relation of the liquid-crystal dielectric coefficient to the applied voltage difference, A is the sum of overlapping areas of the common electrode  31  and the pixel electrode  32  in  FIG. 3 , d is the distance between the common electrode  31  and the pixel electrode  32  in  FIG. 4 . 
     However, the actual size of each radiation unit RU may have slight difference due to the process capability of precision is limited. Therefore, every radiation unit RU will each have their own corrected voltage-capacitance curve C 1 , C 2  . . . Cn (as shown in  FIG. 5B ). The corrected voltage-capacitance curves C 1 , C 2  . . . Cn of the radiation unit RU in the practical situation can be obtained by substituting A (the sum of overlapping areas of the common electrode  31  and the pixel electrode  32 ) and d (the distance between the common electrode  31  and the pixel electrode  32 ) into the aforementioned equation. 
     The corrected voltage-capacitance curves C 1 , C 2  . . . Cn may not only be obtained by the aforementioned equation but also be acquired by directly measuring and calculating the liquid-crystal capacitance C LC  of the radiation unit RU in the practical situation. Referring to  FIG. 6A , which is an equivalent circuit diagram of an integrator for measuring a capacitance of a radiation unit in an embodiment of the present disclosure. First, the accumulated standard electric quantity Q standard  of the standard capacitance C standard  with known capacitance value under the standard applied voltage V standard  can be calculated through the integrator according to the following equation 2.
 
 Q   standard   −C   standard   ×V   standard   (Equation 2)
 
     Next, referring to  FIG. 6B , a fully charged test capacitance (capacitance to be tested) C test  (for example, a capacitance formed by the radiation unit RU) may connect with the integrator of  FIG. 6A , wherein the reduction of the discharge electric quantity Q discharge  results from the discharge of the standard capacitance C standard  as shown in the following equation 3:
 
 Q   discharge   =C   standard   ×V   out   (Equation 3)
 
     Here, output voltage V out  is a function of time t as shown in the following equation 4: 
     
       
         
           
             
               
                 
                   
                     
                       
                         V 
                         out 
                       
                       ⁡ 
                       
                         ( 
                         t 
                         ) 
                       
                     
                     = 
                     
                       
                         
                           - 
                           
                             1 
                             
                               RC 
                               standard 
                             
                           
                         
                         ⁢ 
                         
                           
                             ∫ 
                             
                               t 
                               start 
                             
                             
                               t 
                               end 
                             
                           
                           ⁢ 
                           
                             
                               
                                 V 
                                 in 
                               
                               ⁡ 
                               
                                 ( 
                                 t 
                                 ) 
                               
                             
                             ⁢ 
                             dt 
                           
                         
                       
                       + 
                       
                         V 
                         standard 
                       
                     
                   
                   ⁢ 
                   
                       
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     4 
                   
                   ) 
                 
               
             
           
         
       
     
     In Equation 4, R is the resistance value of the resistor R connected with the aforementioned integrator, V in (t) is a function of the input voltage V in  to the time t, t start  and t end  are the start time and the end time of the input voltage. 
     Subsequently, as shown in Equation 5, the electric quantity Q test  of the test capacitance C test  is obtained by subtracting discharge electric quantity Q discharge  from the standard electric quantity Q standard :
 
 Q   test   =Q   standard   −Q   standard   (Equation 5)
 
     Since the voltage difference V test  of the fully charged test capacitance C test  is known, test capacitance C test  is obtained by the following equation 6: 
     
       
         
           
             
               
                 
                   
                     C 
                     test 
                   
                   = 
                   
                     
                       Q 
                       test 
                     
                     
                       V 
                       test 
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                   ) 
                 
               
             
           
         
       
     
     However, as the capacitance formed by the radiation unit RU includes the liquid-crystal capacitance C LC  and the storage capacitance C st  (which includes parasitic capacitance as well) of the radiation unit RU, a special circuit design is needed to determine the liquid-crystal capacitance C LC  of the radiation unit RU.  FIGS. 7A-7C , which represent equivalent circuit diagrams of the radiation unit of  FIG. 1  at different voltages. As shown in  FIG. 7A , the equivalent circuit of the radiation unit RU includes the source terminal which receives the source voltage V S , wherein the liquid-crystal capacitance C LC  and the storage capacitance C st  connect to a common voltage terminal V com_CLC  and V com_CLC  respectively. 
     First, as shown in  FIG. 7B , a voltage V com_CLC+Cst  may be applied to the common voltage terminals Vcom _CLC  and V com_Cst  of the liquid-crystal capacitance C LC  and the storage capacitance C st , and the voltage Vcom _CLC+Cst  is not equal to the source voltage V S , so as to measure and calculate the parallel equivalent capacitance value of the liquid-crystal capacitance C LC  and the storage capacitance C st . 
     Referring to  FIG. 7C , a voltage equal to the source voltage V S  may be applied to the common voltage terminal V com_CLC  of the liquid-crystal capacitance C LC , and the other voltage V com  may be applied to the common voltage terminal V com_Cst  of the storage capacitance C st , wherein the voltage V com  is not equal to the source voltage V S , so as to measure and calculate the capacitance value of the storage capacitance C st . Next, the liquid-crystal capacitance C LC  of the radiation unit RU can be obtained by subtracting the single capacitance value of the storage capacitance Cst from the parallel equivalent capacitance value of the liquid-crystal capacitance C LC  and the storage capacitance C st . 
     As a result, the corrected voltage-capacitance curve C 1 , C 2  . . . Cn of each radiation unit RU can be obtained by the two aforementioned methods, and the initial voltage-capacitance curve C initial  ( FIG. 5A ) and the corrected voltage-capacitance C 1 , C 2  . . . Cn ( FIG. 5B ) will be stored in the correction module  12  in order to correct the initial voltage signal S 1 , S 2  . . . Sn. Taking the first radiation unit RU 1  as an example, after the correction module  12  receives the initial voltage signal S 1  corresponding to the first radiation unit RU 1 , the correction module  12  can determine an initial capacitance value C 0  corresponding to the initial voltage signal S 1  (V 0  in  FIG. 5A ) according to an initial voltage-capacitance curve, subsequently determine a corrected voltage signal S 1 ′ (V 1  in  FIG. 5A ) corresponding to the initial capacitance value C 0  according to the corrected voltage-capacitance curve C 1  of the first radiation unit RU 1 , and then output the corrected voltage signal S 1 ′ to the aforementioned first radiation unit RU 1 . The initial voltage signal S 1  corresponding to the first radiation unit RU 1  is different from the corrected voltage signal S 1 ′ due to the correction. In some embodiments, initial voltage-capacitance curve C initial  and the corrected voltage-capacitance curves C 1 , C 2  . . . Cn may be stored in the lookup table  121  of the correction module  12 , but are not limited thereto. 
     The present disclosure provides two methods for obtaining the corrected voltage-capacitance curves C 1 , C 2  . . . Cn, but those are merely examples and are not intended to be limited. 
     In summary, the present disclosure utilizes the correction module  12  to correct the voltage signal outputting to the radiation unit RU, which can improve the output electromagnetic wave distortion caused by the non-uniformity of the liquid-crystal layer or the difference of the electrode areas due to the limitation of the process capability of precision, so as to achieve the desired output electromagnetic radiation patterns. 
     The disclosed features may be combined, modified, or replaced in any suitable manner in one or more disclosed embodiments, but are not limited to any particular embodiments. 
     While the disclosure has been described by way of example and in terms of preferred embodiment, it is to be understood that the disclosure is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.