The present disclosure relates to the technical field of microwave transmission, and particularly relates to a phase shifter, a driving method for the phase shifter, and an antenna.
Phased array antennas are widely applied because of no need of precise moving parts of traditional mechanical scanning antennas. Due to the characteristics of low cost and low section, the phased array antennas adopting a liquid crystal phase shifter have become a research focus of the phased array antennas, but high loss of radio frequency signals caused by the use of the liquid crystal phase shifter is an inevitable problem. In order to meet a requirement of a ratio of a gain G of a system receiving antenna to an equivalent noise temperature T value, the gain can be increased by increasing the number of radiating elements to compensate for an insertion loss of the liquid crystal phase shifter. However, since each radiating element uses an individual phase shifter, and a driving voltage of the phase shifter is generally not lower than 15V, how to drive the high-voltage phase shifters of the massive radiating elements becomes a difficult problem.
The present disclosure aims to solve at least one of the technical problems in the prior art, and provides a phase shifter which can separately drive a first reference electrode and a first transmission line, so that bias voltages can be separately input to the first reference electrode and the first transmission line corresponding to one of different regions according to phase shift amounts required for the different regions, and thus a sufficiently large voltage difference between the first reference electrode and the first transmission line can be generated to change a dielectric constant of a first dielectric layer, thereby achieving phase shift better.
In a first aspect, an embodiment of the present disclosure provides a phase shifter, which includes a first substrate and a second substrate, which are disposed opposite to each other, and a first dielectric layer disposed therebetween;
In the phase shifter provided by the embodiment of the present disclosure, since the first reference electrode layer is provided with the plurality of first reference electrodes, a first bias voltage can be independently input to each first reference electrode and then a second bias voltage can be independently input to each first transmission line according to the phase shift amounts required for the different regions, so that a sufficiently large voltage difference can be generated between the first reference electrode and the first transmission line, so as to change the dielectric constant of the first dielectric layer, thereby achieving phase shift better.
In some examples, each first reference electrode is further provided with a second opening, and an orthographic projection of the first opening on the second base does not overlap that of the second opening on the second base; and an orthographic projection of the second transmission end of each first transmission line on the second base at least partially overlaps that of the second opening of the first reference electrode corresponding to the first transmission line on the second base.
In some examples, the phase shifter further includes a first driving unit including a plurality of first channels, a part of the first channels are connected to the first transmission lines one to one, another part of the first channels are connected to the first reference electrodes one to one, and the first driving unit is configured to supply a first bias voltage to each first reference electrode through the first channel and supply a second bias voltage to each first transmission line through the first channel.
In some examples, the first substrate further includes a plurality of first bias lines disposed on the side of the first base close to the first dielectric layer, and each first bias line is connected between one first channel and one first reference electrode; and the second substrate further includes a plurality of second bias lines disposed on the side of the second base close to the first dielectric layer, and each second bias line is connected between one first channel and one first transmission line.
In some examples, the phase shifter further includes a first driving unit and a second driving unit; and the first driving unit includes a plurality of first channels, the first channels is connected to the first reference electrodes one to one, and the first driving unit is configured to supply a first bias voltage to each first reference electrode through the first channel; and
In some examples, the first substrate further includes a plurality of first bias lines disposed on the side of the first base close to the first dielectric layer, and each first bias line is connected between one first channel and one first reference electrode; and the second substrate further includes a plurality of second bias lines on the side of the second base close to the first dielectric layer, and each second bias line is connected between one first channel and one first transmission line.
In some examples, each first transmission line further includes a transmission body; each of the first transmission end and the second transmission end has a first endpoint and a second endpoint, which are disposed opposite to each other; and the first endpoint of the first transmission end and that of the second transmission end are connected with two opposite ends of the transmission body respectively.
In some examples, the transmission body includes a planar spiral transmission line electrically connected with the first transmission end and the second transmission end.
In some examples, the transmission body includes at least one meandering line electrically connected with the first transmission end and the second transmission end; and
In a second aspect, an embodiment of the present disclosure further provides an antenna, which includes the above phase shifter.
In some examples, the antenna further includes a plurality of radiating elements, which are disposed on a side of the first base away from the first dielectric layer; and the radiating elements are in one-to-one correspondence with the first transmission lines, and an orthographic projection of the radiating element on the first base at least partially overlaps that of the first transmission end of the first transmission line corresponding to the radiating element on the first base.
In some examples, the radiating elements are in one-to-one correspondence with the first reference electrodes, and the orthographic projection of the radiating element on the first base at least partially overlaps that of the first reference electrode corresponding to the radiating element on the first base; and
In some examples, each first reference electrode is further provided with the second opening, and the orthographic projection of each radiating element on the first base does not overlap that of the second opening on the first base of the first reference electrode corresponding to the radiating element.
In some examples, the antenna further includes a third substrate disposed on the side of the first base away from the first dielectric layer;
In some examples, the antenna further includes a fourth substrate disposed on a side of the second base away from the first dielectric layer;
In some examples, each first reference electrode is further provided with the second opening; the power-division transmission lines are in one-to-one correspondence with the first reference electrodes, and the orthographic projection of the second end of the power-division transmission line on the fourth base at least partially overlaps that of the second opening of the first reference electrode corresponding to the power-division transmission line on the fourth base.
In a third aspect, an embodiment of the present disclosure further provides a driving method for a phase shifter, which is applied to the above phase shifter and includes:
In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be described in detail below in conjunction with the drawings. Apparently, the embodiments described herein are merely some embodiments of the present disclosure, and do not cover all embodiments. All other embodiments derived by those of ordinary skill in the art from the embodiments described herein without inventive work fall within the scope of the present disclosure.
The shapes and sizes of the components in the drawings do not reflect a true scale, and are merely intended to facilitate an understanding of the contents of the embodiments of the present disclosure.
Unless otherwise defined, technical terms or scientific terms used herein should have general meanings that are understood by those of ordinary skill in the technical field of the present disclosure. The words “first”, “second” and the like used herein do not denote any order, quantity or importance, but are just used to distinguish between different elements. Similarly, the words “one”, “a”, “the” and the like do not denote a limitation to quantity, and indicate the existence of “at least one” instead. The words “include”, “comprise” and the like indicate that an element or object before the words covers the elements or objects or the equivalents thereof listed after the words, rather than excluding other elements or objects. The words “connect”, “couple” and the like are not restricted to physical or mechanical connection, but may also indicate electrical connection, whether direct or indirect. The words “on”, “under”, “left”, “right” and the like are only used to indicate relative positional relationships. When an absolute position of an object described is changed, the relative positional relationships may also be changed accordingly.
The embodiments of the present disclosure are not limited to those illustrated by the drawings, but include modifications to configuration formed based on a manufacturing process. Thus, the regions shown in the drawings are illustrative, and the shapes of the regions shown in the drawings illustrate specific shapes of the regions of the elements, but are not intended to make limitations.
Before describing the following embodiments, it should be noted that a first dielectric layer in a phase shifter provided in the following embodiments includes, but is not limited to, a liquid crystal layer, and a case where the first dielectric layer is the liquid crystal layer is merely taken as an example in the following description. When a first transmission end of a first transmission line in the phase shifter is used as a receiving end, a second transmission end of the first transmission line is used as a sending end; and when the second transmission end of the first transmission line is used as the receiving end, the first transmission end of the first transmission line is used as the sending end. In the following description, a case where the first transmission end of the transmission line is taken as the sending end and the second transmission end of the transmission line is taken as the receiving end is taken as an example for convenience of understanding, but the present disclosure is not limited thereto.
In addition, the first transmission line may be a delay line or a strip transmission line in the embodiments of the present disclosure. For convenience of description, the delay line is taken as an example of the first transmission line in the embodiments of the present disclosure, and a shape of the delay line includes, but is not limited to, any one or a combination of more than one of a bow shape, a wave shape and a zigzag shape.
With reference to
In order to solve the above problem, an embodiment of the present disclosure provides a phase shifter, which is described below.
In a first aspect, with reference to
The second substrate includes a second base 21, and a plurality of first transmission lines 22 disposed on a side of the second base 21 close to the first dielectric layer 3 and spaced apart from one another. The first transmission lines 22 are in one-to-one correspondence with the first reference electrodes 12, an orthographic projection of the first transmission line 22 on the second base 21 at least partially overlaps that of the first reference electrode 12 corresponding to the first transmission line 22 on the second base 21, and the first transmission line 22 and the first reference electrode 12 corresponding thereto form a phase shift unit. The phase shifter includes a plurality of phase shift units arranged in an array, and each phase shift unit is capable of independently adjusting a phase shift amount of a region where the phase shift unit is located.
Since the plurality of first reference electrodes 12 are disposed on the side of the first base 11 close to the first dielectric layer 3 and spaced apart from one another, a first bias voltage V1 may be separately input to each first reference electrode 12 and then a second bias voltage V1′ may be separately input to each first transmission line 22 according to the phase shift amounts required for the different regions of the phase shifter, so that a sufficiently large voltage difference can be generated between the first reference electrode 12 and the first transmission line 22 to change the dielectric constant of the first dielectric layer 3, thereby achieving phase shift better. Specifically, with reference to
In some examples, with reference to
In some examples, when the first transmission end 22a serves as a sending end of a microwave signal, the second transmission end 22b serves as a receiving end of the microwave signal; accordingly, when the second transmission end 22b serves as the sending end of the microwave signal, the first transmission end 22a serves as the receiving end of the microwave signal. As described above, taking a case where the first transmission end 22a of the first transmission line 22 is the sending end as an example, an orthographic projection of the first transmission end 22a of each first transmission line 22 on the second base 21 at least partially overlaps that of the first opening 121 of the first reference electrode 12 corresponding to the first transmission line 22 on the second base 21, so that the microwave signal is received through the second transmission end 22b of the first transmission line 22 and then is transmitted to the first transmission end 22a, and the first transmission end 22a couples the microwave signal out of the phase shifter through the first opening 121 of the first reference electrode 12. In some examples, an extending direction of the orthographic projection of the first transmission end 22a on the second base 21 may penetrate through a center of the orthographic projection of the first opening 121 on the second base 21.
In some examples, the first opening 121 may be in any shape, for example, the first opening 121 may be a circular opening or a polygonal opening, and the polygonal opening includes a rectangular opening, a triangular opening, a trapezoidal opening, etc. If the first opening 121 is the polygonal opening, the orthographic projection of the first transmission end 22a on the second base 21 only overlaps one side of the orthographic projection of the first opening 121 on the second base 21; and if the first opening 121 is the circular opening, the orthographic projection of the first transmission end 22a on the second base 21 overlaps that of the first opening 121 on the second base 21 only at a point on a circular edge of the orthographic projection of the first opening 121.
In some examples, with reference to
In some examples, the second opening 122 may be in any shape, for example, the second opening 122 may be a circular opening or a polygonal opening, and the polygonal opening includes a rectangular opening, a triangular opening, a trapezoidal opening, etc. If the second opening 122 is the polygonal opening, the orthographic projection of the second transmission end 22b on the second base 21 only overlaps one side of the orthographic projection of the second opening 122 on the second base 21; and if the second opening 122 is the circular opening, the orthographic projection of the second transmission end 22b on the second base 21 overlaps that of the second opening 122 on the second base 21 only at a point on a circular edge of the orthographic projection of the second opening 122.
In some examples, the first transmission line 22 may have a plurality of specific shapes, for example, with reference to
As another example, with reference to
In some examples, when the transmission body 22c includes a plurality of meandering lines, the shapes of the meandering lines are at least partially different from one another. That is, it is possible that a part of the plurality of meandering lines may have the same shape, or all of the plurality of meandering lines are different in shape.
In some examples, the transmission body 22c of the first transmission line 22 includes at least one meandering line electrically connected to the first transmission end 22a and the second transmission end 22b; and an orthographic projection of the at least one meandering line on the first base 11 has a portion intersecting with an extending direction of an orthographic projection of the first transmission end 22a on the first base 11. In such case, spaces occupied by the first transmission lines 22 in the phase shifter may be reduced, so that a volume of the phase shifter may be reduced. The transmission body 22c may also be in other shapes, such as a bow shape, a wave shape and a zigzag shape, but the shape of the transmission body 22c is not limited herein.
In some examples, with reference to
It should be noted that, in the embodiments of the present disclosure, the phase shifter further includes a first wiring board and a second wiring board; the first wiring board is bonded and connected to the first substrate and is configured to supply the first bias voltage to the first bias line 01. The second wiring board is bonded and connected to the second substrate and is configured to supply the second bias voltage to a second bias line 02. Each of the first wiring board and the second wiring board may include various types of wiring boards, such as a Flexible Printed Circuit (FPC) board and a Printed Circuit Board (PCB), and the types of the first and second wiring boards are not limited herein. The first wiring board may be provided thereon with at least one first pad, one end of the first bias line 01 is connected (i.e., bonded) to the first pad, and the other end of the first bias line 01 is connected to one first reference electrode 12; and the second wiring board may also be provided thereon with at least one second pad, one end of the second bias line 02 is connected (i.e., bonded) to the second pad, and the other end of the second bias line 02 is connected to one first transmission line 22.
In some examples, orthographic projections of all the first bias lines 01 on the first base 11 do not overlap one another; and orthographic projections of the second bias lines 02 on the second base 21 do not overlap one another.
In some examples, with reference to
In some examples, two driving units may be disposed to drive the first reference electrodes 12 and the first transmission lines 22, respectively. With reference to
With reference to
In some examples, the first driving unit 001 and/or the second driving unit 002 may specifically be an HX8157 drive chip of HIMAX, and may be specifically set according to phase shift performance required by the phase shifter.
In some examples, with reference to
In some examples, the first reference electrode 12 may be made of a metal material, such as any one of copper, aluminum, gold and silver. A thickness of the first reference electrode 12 is about 0.1 μm to 100 μm. The parameters of the first reference electrode 12, such as the specific material and the specific thickness, may be specifically set according to requirements for the size and the performance of the phase shifter.
In some examples, in addition to including the above structures, the phase shifter further includes a support structure (not shown) and a sealant 4; the sealant 4 is disposed between the first substrate and the second substrate in a peripheral region and surrounds a microwave transmission region and is configured to seal a liquid crystal cell (the first dielectric layer 3 is the liquid crystal layer) of the phase shifter; and the support structure is disposed between the first substrate and the second substrate, there may be a plurality of support structures, and all the support structures are spaced apart from one another in the microwave transmission region for maintaining a thickness of the liquid crystal cell.
In some examples, the support structure in the embodiment of the present disclosure may be made of an organic material and have certain elasticity, so as to avoid the problem of breakage of the first base 11 and the second base 21 due to an external force when the phase shifter is pressed. Further, appropriate spherical particles may be added to the support structure, so as to guarantee stability of the support structure while the support structure maintains the thickness of the liquid crystal cell.
In some examples, the first bias line 01 and/or the second bias line 02 are/is made of a high-resistance material, and the electric field generated by the first bias line 01 and/or the second bias line 02 and the first reference electrode 1 when the bias voltage is applied to the first bias line 01 and/or the second bias line 02 is only configured to drive the liquid crystal molecules in the first dielectric layer 3 to deflect, and is equivalent to an open circuit for the microwave signal transmitted by the phase shifter, that is, the microwave signal is transmitted only along the first transmission line 22. Conductivity of the first bias line 01 and/or the second bias line 02 is less than 14500000 siemens/m; and when the first bias line 01 and/or the second bias line 02 are/is selected according to the size of the phase shifter, the lower the conductivity of the first bias line 01 and/or the second bias line 02, the better. In some examples, the material of the first bias line 01 and/or the second bias line 02 includes, but is not limited to, any one of Indium Tin Oxide (ITO), nickel (Ni), tantalum nitride (TaN), chromium (Cr), indium oxide (In2O3), and Tin Oxide (Sn2O3). In some implementations, the first bias line 01 and/or the second bias line 02 are/is made of ITO.
In some examples, the first transmission line 22 is made of a metal material. Specifically, the material of the first transmission line 22 is made of a metal, such as, but not limited to, aluminum, silver, gold, chromium, molybdenum, nickel or iron.
In some examples, the first base 11 may be made of a plurality of materials. For example, if the first base 11 is a flexible base, the material of the first base 11 may include at least one of polyethylene glycol terephthalate (PET) and Polyimide (PI); and if the first base 11 is a rigid base, the material of the first base 11 may be glass and the like. A thickness of the first base 11 may be about 0.1 mm to 1.5 mm. The second base 21 may also be made of a plurality of materials. For example, if the second base 21 is a flexible base, the material of the second base 21 may include at least one of polyethylene glycol terephthalate (PET) and Polyimide (PI); and if the second base 21 is a rigid base, the material of the second base 21 may also be glass and the like. A thickness of the second base 21 may be about 0.1 mm to 1.5 mm. The first base 11 and the second base 21 may also be made of the other materials that are not limited herein. The specific thicknesses of the first base 11 and the second base 21 may also be set according to a skin depth of an electromagnetic wave (a radio frequency signal).
In some examples, a thickness of the first dielectric layer 3 which is the liquid crystal layer is about 1 μm to 1 mm. Specifically, the thickness of the first dielectric layer 3 may be set according to the requirements for the size and a phase shift angle of the phase shifter. In addition, the first dielectric layer 3 in the embodiment of the present disclosure is made of a microwave liquid crystal material. For example, the liquid crystal molecules in the first dielectric layer 3 are positive liquid crystal molecules or negative liquid crystal molecules. It should be noted that, in a case where the liquid crystal molecules are positive liquid crystal molecules, an included angle between a long axis direction of the liquid crystal molecules and the second electrode is greater than 0° and smaller than or equal to 45° according to the embodiment of the present disclosure. In a case where the liquid crystal molecules are negative liquid crystal molecules, an included angle between the long axis direction of the liquid crystal molecules and the second electrode is larger than 45° and smaller than 90° according to the embodiment of the present disclosure. Thus, it may be ensured that the dielectric constant of the first dielectric layer 3 is changed after the liquid crystal molecules are deflected, thereby achieving phase shift.
In some examples, the first substrate further includes a first alignment layer (not shown) disposed on a side of the first reference electrodes 12 away from the first base 11; and a second alignment layer (not shown) disposed on a side of the first transmission lines 22 away from the second base 21. The first alignment layer and the second alignment layer are configured to align the liquid crystal molecules in the first dielectric layer 3. Both the first alignment layer and the second alignment layer may be made of polyimide materials. Thicknesses of the first alignment layer and the second alignment layer may be about 30 nm to 2 μm.
In a second aspect, an embodiment of the present disclosure further provides a driving method for a phase shifter, which is applied to the above phase shifter, and includes:
Specifically, when the phase shifter is applied to an antenna, phase compensations required by different radiating elements are different in a scanning process of the antenna, that is, the phase shift amounts required by the phase shift units in the regions where the different first transmission lines 22 are located are different, a correspondence table of driving voltage and phase shift amount may be preset in the control unit, the preset correspondence table is searched for a driving voltage according to the phase shift amount required by the region where the first transmission line 22 corresponding to one radiating element is located, and a corresponding first bias voltage and a corresponding second bias voltage are generated according to the found driving voltage, with a difference between the first bias voltage and the second bias voltage equal to the driving voltage.
In some examples, the first bias voltage and the second bias voltage may be voltages having a same value and opposite polarities. It should be noted that the first driving unit 001 or the second driving unit 002 has its own reference voltage, and a median of a voltage range thereof is usually used as the reference voltage. For example, if an output voltage range of the first driving unit 001 is 0V to 18V, 9V may be used as the reference voltage of the first driving unit 001, and whether the polarities of the first bias voltage and the second bias voltage are positive or negative is determined with respect to the reference voltage, that is, the first bias voltage or the second bias voltage smaller than the reference voltage (9V) has a negative polarity, and the first bias voltage or the second bias voltage greater than or equal to the reference voltage (9V) has a positive polarity. For example, assuming that the driving voltage required for the region where one first transmission line 22 is located in the phase shifter is xV, the first bias voltage may be set to (9+x/2)V, and the second bias voltage may be set to (9−x/2)V; since the LVDS data input to the driving unit (the first driving unit 001 or the second driving unit 002) are the same, i.e., (x/2)V, the first bias voltage and the second bias voltage may be obtained merely by selecting digital-to-analog converters having different polarities to change the polarities of the output voltages, so that a sufficient voltage different may be obtained to drive the phase shifter without adding extra data, and the second bias voltage of the first transmission line 22 and the first bias voltage of the first reference electrode 12 may be flexibly set for each region. Moreover, by reversing the polarities of the first bias voltage to the first reference electrode 12 and the second bias voltage to the first transmission line 22, it is possible to prevent the liquid crystal molecules in the first dielectric layer 3 from being polarized to cause a decrease in the performance of the phase shifter.
Taking a case where the phase shifter is applied to a 1×4 antenna array as an example, that is, simulation is performed based on a model of the phase shifter which includes phase shift units sequentially arranged along a same direction, and simulation results of port parameters (reflection characteristic Sii, transmission characteristic Sij), a gain (in normal direction) and a bandwidth (a relationship between the gain and a frequency), Sii in a vertical state of liquid crystal, Sii in a mixed state of liquid crystal, Sii in a parallel state of liquid crystal, Sij in the vertical state of liquid crystal, Sij in the mixed state of liquid crystal, Sij in the parallel state of liquid crystal, a normal radiation pattern in the vertical state of liquid crystal, a normal radiation pattern in the mixed state of liquid crystal, and a normal radiation pattern in the parallel state of liquid crystal are shown in the following table. In the table, {circle around (1)} represents an antenna adopting the phase shifter including the first reference electrode layer which is the surface electrode, {circle around (2)} represents an antenna adopting the phase shifter provided by the embodiment of the present disclosure, it can be seen from the table that the performance parameters of the two antennas are not greatly different, so that it can be verified that the phase shifter provided by the embodiment of the present disclosure has good performance.
In a third aspect, an embodiment of the present disclosure further provides an antenna, including the above phase shifter.
In some examples, the antenna further includes a plurality of radiating elements 33, which are disposed on the side of the first base 11 away from the first dielectric layer 3. The radiating elements 33 are in one-to-one correspondence with the first transmission lines 22, and an orthographic projection of one radiating element 33 on the first base 11 at least partially overlaps that of the first transmission end 22a of the first transmission line 22 corresponding to the radiating element 33 on the first base 11.
In some examples, the radiating elements 33 are in one-to-one correspondence with the first reference electrodes 12, and the orthographic projection of one radiating element 33 on the first base 11 at least partially overlaps that of the first reference electrode 12 corresponding to the radiating element 33 on the first base 11; and the orthographic projection of each radiating element 33 on the first base 11 at least partially overlaps that of the first opening 121 of the first reference electrode 12 corresponding thereto on the first base 11, but does not overlap an orthographic projection of the second opening 122 of the first reference electrode 12 corresponding thereto on the first base 11. By a process of forming a metal on both sides of a glass substrate (the first base 11), the radiating elements 33 and the first reference electrodes 12 are respectively formed on two sides of the first base 11, and the first openings 121 are covered by the radiating elements 33 respectively and face the first transmission ends 22a of the first transmission lines 22 respectively. Taking a case where the first transmission end 22a is the sending end, the first transmission end 22a couples a microwave signal to the radiating element 33 through the first opening 121.
In some examples, with reference to
In some examples, the third substrate may be a PCB.
In some examples, with reference to
In some examples, each first reference electrode 12 is further provided with the second opening 122. The power-division transmission lines 43b of the power-division transmission structure 43 are in one-to-one correspondence with the first reference electrodes 12, and the orthographic projection of the second end of the power-division transmission line 43b on the fourth base 41 at least partially overlaps that of the second opening 122 of the first reference electrode 12 corresponding to the power-division transmission line 43b on the fourth base 41.
In some examples, the power-division transmission structure 43 may be disposed on the side of the second base 21 close to the first dielectric layer 3, that is, the power-division transmission structure 43 is disposed in the same layer as the first transmission lines 22, and the second end of the power-division transmission line 43b is electrically connected to the second transmission end 22b of the first transmission line 22 corresponding to the power-division transmission line 43b. Moreover, a second reference electrode layer 41 is disposed on the side of the second base 21 away from the first dielectric layer 3. In this case, the fourth substrate is not needed, so that a thickness of the antenna may be reduced.
It should be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present disclosure, and the present disclosure is not limited thereto. Various modifications and improvements can be made by those of ordinary sill in the art without departing from the spirit and essence of the present disclosure, and those modifications and improvements are also considered to fall within the scope of the present disclosure.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/CN2021/082615 | 3/24/2021 | WO |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2022/198481 | 9/29/2022 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
9972905 | Schaffner | May 2018 | B2 |
20050248423 | Qian et al. | Nov 2005 | A1 |
20070013466 | Hersey et al. | Jan 2007 | A1 |
20110273228 | Kolias et al. | Nov 2011 | A1 |
20210367336 | Jia et al. | Nov 2021 | A1 |
20210408680 | Xi | Dec 2021 | A1 |
20220006166 | Li et al. | Jan 2022 | A1 |
Number | Date | Country |
---|---|---|
112397854 | Feb 2021 | CN |
112448106 | Mar 2021 | CN |
Number | Date | Country | |
---|---|---|---|
20230352804 A1 | Nov 2023 | US |