Cholesterol liquid crystal panel

Abstract

The application discloses a cholesteric liquid crystal panel, which comprises a first substrate, a second substrate, a first electrode, a second electrode, a third electrode, a fourth electrode and a cholesteric liquid crystal layer. The first substrate and the second substrate are arranged in an overlapping manner. The first electrode and the second electrode are arranged on the first substrate and are electrically independent from each other. The first electrode has a plurality of first comb-shaped parts. The third electrode and the fourth electrode are arranged on the second substrate and are electrically independent from each other. The third electrode has a plurality of third comb-shaped parts. The extending directions of the first comb-shaped parts of the first electrode intersect with the extending directions of the third comb-shaped parts of the third electrode. The cholesteric liquid crystal layer is arranged between the first substrate and the second substrate and is adapted to switch between a first state and a second state.

Description

TECHNICAL FIELD

[0001] The present application relates to a liquid crystal panel, and in particular to a cholesteric liquid crystal panel. BACKGROUND

[0002] In recent years, flexible displays, electronic paper and electronic books are developing rapidly, and the display technologies used include cholesteric liquid crystal display technology, electrophoretic display technology and electrochromic display technology. Because cholesteric liquid crystal display technology has the characteristics of passive driving and better brightness and contrast performance compared with other display technologies, it has become one of the mainstream technologies for electronic paper applications.

[0003] Generally, the molecular arrangement state of cholesteric liquid crystal can include two stable arrangement states, i.e. planar state and focal-conic state. When cholesteric liquid crystal is to be switched from focal-conic state to planar state, a critical voltage greater than 40 volts must be provided to drive the cholesteric liquid crystal. In addition, because cholesteric liquid crystal needs to be switched to homeotropic state before forming planar state arrangement during the process of switching from focal-conic state to planar state, the switching time between bistable states is too long. In order to make cholesteric liquid crystal suitable for active driving architecture, reducing its bistable switching voltage and switching time is an important and unsolved problem. SUMMARY

[0004] The present application provides a cholesteric liquid crystal panel, which has faster switching speed between different stable states of liquid crystal molecular arrangement and lower switching voltage.

[0005] The cholesteric liquid crystal panel of the present application comprises a first substrate, a second substrate, a first electrode, a second electrode, a third electrode, a fourth electrode and a cholesteric liquid crystal layer. The first substrate and the second substrate are arranged to overlap each other. The first electrode and the second electrode are arranged on the first substrate and are electrically independent of each other. The first electrode has a plurality of first comb-shaped portions. The third electrode and the fourth electrode are arranged on the second substrate and are electrically independent of each other. The third electrode has a plurality of third comb-shaped portions. The extension directions of the first comb-shaped portions of the first electrode intersect the extension directions of the third comb-shaped portions of the third electrode. The cholesteric liquid crystal layer is arranged between the first substrate and the second substrate and is adapted to switch between a first state and a second state.

[0006] Based on the above, in the cholesterol liquid crystal panel of the first embodiment of the present application, the first substrate is provided with a first electrode comprising a plurality of first comb-shaped portions, and the second substrate is provided with a second electrode comprising a plurality of second comb-shaped portions. The extending directions of the first comb-shaped portions intersect with the extending directions of the second comb-shaped portions. When the first electrode, the second electrode, the third electrode and the fourth electrode are enabled, the horizontal electric field and the vertical electric field formed between the electrodes can enable the cholesterol liquid crystal panel to switch between the bistable arrangements without driving through the intermediate state. Therefore, the driving voltage required by the cholesterol liquid crystal panel when switching between the bistable arrangements can be effectively reduced, and the switching time can also be greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a top view schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application;

[0008] Figure 2 is a top view schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application; Figure 3

[0009] Figure 3 is a cross-sectional view schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application maintained in the first state;

[0010] Figure 4 is a cross-sectional view schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application electrically switched from the first state to the second state;

[0011] Figure 5 is a cross-sectional view schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application maintained in the second state;

[0012] Figure 6A Figure 6B is a cross-sectional view schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application electrically switched from the second state to the first state;

[0013] Figure 7 is a driving waveform schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application when electrically switched from the first state to the second state;

[0014] Figure 8A Figure 8B is a driving waveform schematic diagram of the cholesterol liquid crystal panel of the first embodiment of the present application when electrically switched from the second state to the first state;

[0015] Figure 9 Figure 10 is a top view schematic diagram of the first electrode, the second electrode, the third electrode and the fourth electrode of another variant embodiment of the present application;

[0016] Figure 11 Figure 12 ​​​​​is a top view schematic diagram of first, second, third and fourth electrodes of a still further variant embodiment of the present application;

[0017] Figure 13 and Figure 14 is a top view schematic diagram of first, second, third and fourth electrodes of a still further variant embodiment of the present application;

[0018] Figure 15 is a sectional view schematic diagram of a cholesterol liquid crystal panel of a second embodiment of the present application;

[0019] Figure 16 is Figure 15 a top view schematic diagram of partial film layers of the cholesterol liquid crystal panel of

[0020] Symbol explanation

[0021] 10, 20: cholesterol liquid crystal panel

[0022] 101: first substrate

[0023] 102: second substrate

[0024] 150: cholesterol liquid crystal layer

[0025] 150FC: focal conic state

[0026] 150PL: planar state

[0027] 180: gap material

[0028] D1, D2, D3, D1', D2', D1'', D2'': direction

[0029] E1, E1-A, E1-B, E1-C, E1-D: first electrode

[0030] E1c, E1c1, E1c2, E1c-B, E1c11, E1c12, E1c21, E1c22: first comb-shaped portion

[0031] E1c3, E1c4, E3c3, E3c4: conical portion

[0032] E1m-B, E2m-B, E3m-B, E4m-B, E2m, E2m-C, E3m, E3m-C: connecting portion

[0033] E1m1, E1m1-C, E4m1-C: first connecting portion

[0034] E1m2, E1m2-C, E4m2-C: second connecting portion

[0035] E1_EN, E2_EN, E3_EN, E4_EN, E1_EN', E2_EN', E3_EN', E4_EN', E1_EN'', E2_EN'', E3_EN'', E4_EN'': driving signal

[0036] E2, E2-A, E2-B, E2-C, E2-D: second electrode

[0037] E2c, E2c1, E2c2, E2c-B, E2c11, E2c12, E2c21, E2c22: second comb

[0038] E3, E3-A, E3-B, E3-C, E3-D: third electrode

[0039] E3c, E3c1, E3c2, E3c-B, E3c11, E3c12, E3c21, E3c22: third comb

[0040] E4, E4-A, E4-B, E4-C, E4-D: fourth electrode

[0041] E4c, E4c1, E4c2, E4c-B, E4c11, E4c12, E4c21, E4c22: fourth comb

[0042] E4m1: first connecting part

[0043] E4m2: second connecting part

[0044] EFh1, EFh2: horizontal electric field

[0045] EFv1, EFv2: vertical electric field

[0046] INS1, INS2: insulating layer

[0047] S1: first interval

[0048] S2: second interval

[0049] TP1: first time interval

[0050] TP2: second time interval

[0051] V1, V1': first voltage

[0052] V2, V2': second voltage

[0053] V3: third voltage

[0054] V4: fourth voltage

[0055] W1: first width

[0056] W2: Second width Detailed Implementation

[0057] As used herein, “about,” “approximately,” “essentially,” or “substantially” includes the value and the average value within an acceptable range of deviations from a particular value as determined by one of ordinary skill in the art, taking into account the measurement in question and a particular number of errors associated with the measurement (i.e., limitations of the measurement system). For example, “about” may mean within one or more standard deviations of the value, or, for example, within ±30%, ±20%, ±15%, ±10%, ±5%. Furthermore, the use of “about,” “approximately,” “essentially,” or “substantially” herein may be chosen to select a more acceptable range of deviations or standard deviations depending on the nature of the measurement, the cutting nature, or other properties, and a single standard deviation may not be applicable to all properties.

[0058] In the accompanying drawings, the thicknesses of layers, films, panels, regions, etc., are enlarged for clarity. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected" to another element, it may be directly on or connected to the other element, or intermediate elements may also be present. Conversely, when an element is referred to as being "directly on" or "directly connected" to another element, no intermediate elements are present. As used herein, "connection" can refer to a physical and / or electrical connection. Furthermore, an "electrical connection" may involve the presence of other elements between the two elements.

[0059] Furthermore, relative terms such as "below" or "bottom" and "above" or "top" may be used herein to describe the relationship between one element and another, as illustrated in the figures. It should be understood that relative terms are intended to include different orientations of the device beyond those shown in the figures. For example, if a device in one figure is flipped, an element described as being "below" to another element will be oriented "above" to that element. Thus, the exemplary term "below" can include both "below" and "above" orientations, depending on the specific orientation of the figure. Similarly, if a device in one figure is flipped, an element described as being "below" or "under" another element will be oriented "above" to that element. Thus, the exemplary terms "above" or "below" can include both "above" and "below" orientations.

[0060] The exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments. Variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are expected to occur. Thus, embodiments described herein are not to be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result from, for example, manufacturing. For example, an area illustrated or described as flat can often have rough and / or nonlinear features. Moreover, sharp angles that are illustrated can be rounded. Thus, the regions illustrated in the figures are schematic and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.

[0061] Reference will now be made in detail to the exemplary embodiments of the application, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0062] Figure 1 is a top view schematic diagram of a cholesteric liquid crystal panel according to the first embodiment of the present application. Figure 2 is Figure 3 is a schematic diagram of partial film layers of the cholesteric liquid crystal panel. Figure 3 is a cross-sectional schematic diagram of the cholesteric liquid crystal panel according to the first embodiment of the present application maintained in the first state. Figure 4 is a cross-sectional schematic diagram of the cholesteric liquid crystal panel according to the first embodiment of the present application electrically controlled switched from the first state to the second state. Figure 5 is a cross-sectional schematic diagram of the cholesteric liquid crystal panel according to the first embodiment of the present application maintained in the second state. Figure 6A and Figure 6B is a cross-sectional schematic diagram of the cholesteric liquid crystal panel according to the first embodiment of the present application electrically controlled switched from the second state to the first state. Figure 7 is a schematic diagram of drive waveforms when the cholesteric liquid crystal panel according to the first embodiment of the present application is electrically controlled switched from the first state to the second state. Figure 8A and Figure 8B is a schematic diagram of drive waveforms when the cholesteric liquid crystal panel according to the first embodiment of the present application is electrically controlled switched from the second state to the first state. For clarity of presentation, Figure 1 the illustration of the second substrate 102, the cholesteric liquid crystal layer 150 and the spacer 180 of Figure 3 is omitted.

[0063] Please refer to Figures 1 to 3The cholesteric liquid crystal panel 10 includes a first substrate 101, a second substrate 102, a first electrode E1, a second electrode E2, a third electrode E3, a fourth electrode E4, and a cholesteric liquid crystal layer 150. The cholesteric liquid crystal layer 150 is disposed between the first substrate 101 and the second substrate 102, and is adapted to switch between a first state and a second state. The first electrode E1 and the second electrode E2 are disposed on the first substrate 101, and are electrically independent from each other. The third electrode E3 and the fourth electrode E4 are disposed on the second substrate 102, and are electrically independent from each other. The first electrode E1 and the second electrode E2 overlap the third electrode E3 and the fourth electrode E4 along a stacking direction (e.g., direction D3) of the first substrate 101 and the second substrate 102. In this embodiment, the first electrode E1 and the second electrode E2 can be the same film layer, and the third electrode E3 and the fourth electrode E4 can be the same film layer, but the present disclosure is not limited thereto.

[0064] In this embodiment, the first electrode E1, the second electrode E2, the third electrode E3, and the fourth electrode E4 are all comb electrodes, for example. For example, the first electrode E1 has a plurality of first comb portions E1c, the second electrode E2 has a plurality of second comb portions E2c, the third electrode E3 has a plurality of third comb portions E3c, and the fourth electrode E4 has a plurality of fourth comb portions E4c. However, the present disclosure is not limited thereto. In other embodiments, the first electrode E1 or the second electrode E2 can not have comb portions, and the third electrode E3 or the fourth electrode E4 can not have comb portions.

[0065] In this embodiment, the plurality of first comb portions E1c of the first electrode E1 and the plurality of second comb portions E2c of the second electrode E2 can be alternately arranged along a direction D1 (i.e., a first direction), and the plurality of third comb portions E3c of the third electrode E3 and the plurality of fourth comb portions E4c of the fourth electrode E4 can be alternately arranged along a direction D2 (i.e., a second direction), wherein the direction D1 can be selectively perpendicular to the direction D2. In another aspect, the extension direction of the first comb portions E1c and the second comb portions E2c intersects (e.g., is perpendicular to) the extension direction of the third comb portions E3c and the fourth comb portions E4c.

[0066] With the above electrode configuration, the diversity of the electric field pointing of the plurality of liquid crystal molecules LC of the cholesteric liquid crystal layer 150 used by the cholesteric liquid crystal panel 10 to drive the cholesteric liquid crystal layer 150 can be increased.

[0067] The first and second plurality of comb-like portions E1c and E2c each have a first width W1 along the direction D1, and any two adjacent ones of them have a first pitch S1 along the direction D1. For example, in the present embodiment, the sum of the first width W1 and the first pitch S1 is 8 microns. Preferably, the first width W1 is in the range of 3.0 to 3.2 microns, and the first pitch S1 is in the range of 4.8 to 5.0 microns. Most preferably, the first width W1 is 3.1 microns, and the first pitch S1 is 4.9 microns.

[0068] Similarly, the third and fourth plurality of comb-like portions E3c and E4c each have a second width W2 along the direction D2, and any two adjacent ones of them have a second pitch S2 along the direction D2. For example, in the present embodiment, the sum of the second width W2 and the second pitch S2 is 8 microns. Preferably, the second width W2 is in the range of 3.0 to 3.2 microns, and the second pitch S2 is in the range of 4.8 to 5.0 microns. Most preferably, the second width W2 is 3.1 microns, and the second pitch S2 is 4.9 microns.

[0069] It is noted that the preferred ranges of the widths and the pitches of the comb-like portions described above can be adjusted according to the thickness of the cholesteric liquid crystal layer 150 and the liquid crystal material, and the present application is not limited thereto. For example, the widths and the pitches of the comb-like portions described above are the preferred values for the cholesteric liquid crystal layer 150 having a thickness of 3.7 microns.

[0070] On the other hand, the first, second, third and fourth electrodes E1, E2, E3 and E4 are, for example, light-transmissive electrodes, and the material of the light-transmissive electrodes includes metal oxides, such as indium tin oxide, indium zinc oxide, aluminum tin oxide, aluminum zinc oxide, or other suitable oxides, or a stack of at least two of the above.

[0071] However, the present application is not limited thereto. In other embodiments, the materials of the first, second, third and fourth electrodes E1, E2, E3 and E4 can also be selected to be different, for example, the materials of the first and second electrodes E1 and E2 (or the third and fourth electrodes E3 and E4) can include metals, alloys, nitrides of metal materials, oxides of metal materials, oxides of metal materials, or other suitable materials, or a stack of metal materials and other conductive materials.

[0072] In the present embodiment, the plurality of liquid crystal molecules LC of the cholesteric liquid crystal layer 150 can be maintained in two bistable states, a first state and a second state. For example, the first state is, for example, a focal-conic state 150FC, and the second state is, for example, a planar state 150P. Figure 3 The focal-conic state 150FC is shown, and the planar state 150P is shown. Figure 5The planar state 150PL is shown, but not limited thereto. Here, bistability refers to the fact that the cholesteric liquid crystal layer 150 can form two stable alignment states when no electric field is applied. The cholesteric liquid crystal layer 150 is, for example, a nematic liquid crystal doped with a chiral dopant, so that the liquid crystal molecules LC are twisted with a specific pitch.

[0073] It is particularly noted that the cholesteric liquid crystal layer 150 can exhibit different optical properties in the two bistable states. For example, when the cholesteric liquid crystal layer 150 is aligned in the focal conic state 150FC (as shown in FIG. 1B), it will diffuse the light, so that the cholesteric liquid crystal layer 150 appears to be in a haze state. When the cholesteric liquid crystal layer 150 is aligned in the planar state 150PL (as shown in FIG. 1A), it will reflect light of a specific wavelength and transmit light of other wavelengths, wherein the wavelength of the light reflected by the cholesteric liquid crystal layer 150 in the planar state 150PL depends on the pitch of the cholesteric liquid crystal layer 150. Figure 3 Figure 5

[0074] For example, the cholesteric liquid crystal panel 10 can be used as a transparent display, wherein the wavelength of the light reflected by the cholesteric liquid crystal layer 150 in the planar state 150PL can be designed in the infrared light band, and the cholesteric liquid crystal layer 150 is adapted to transmit visible light (i.e., in a transparent state). Thus, by making a part of the cholesteric liquid crystal layer 150 exhibit the haze state (e.g., the cholesteric liquid crystal layer 150 in the part is maintained in the focal conic state 150FC), and making the cholesteric liquid crystal layer 150 in other areas exhibit the transparent state, the effect of transparent display can be achieved.

[0075] The following will be exemplarily described with respect to the driving method of the cholesteric liquid crystal panel 10 in switching between the two bistable states (e.g., the focal conic state 150FC and the planar state 150PL). Figure 3 Figure 5

[0076] Please refer to Figure 3 , Figure 4 and Figure 7 ​​​​When the cholesteric liquid crystal panel 10 is to be switched from the focal conic state 150FC (i.e., the first state) to the planar state 150PL (i.e., the second state), the first electrode E1 and the third electrode E3 are enabled to have the first voltage V1, the second electrode E2 and the fourth electrode E4 are enabled to have the second voltage V2, and the first voltage V1 is different from the second voltage V2. More specifically, the polarities of the driving signal E1_EN applied to the first electrode E1 and the driving signal E3_EN applied to the third electrode E3 are opposite to the polarities of the driving signal E2_EN applied to the second electrode E2 and the driving signal E4_EN applied to the fourth electrode E4, and these driving signals are, for example, alternating current signals with a fixed period.

[0077] For example, in one half period of time, the first voltage V1 is +20V and the second voltage V2 is -20V, and in the other half period of time, the first voltage V1 is switched to -20V and the second voltage V2 is switched to +20V. Thus, when the first electrode E1 and the third electrode E3 are applied with the same driving signal E1_EN and the driving signal E3_EN, respectively, and the second electrode E2 and the fourth electrode E4 are applied with the same driving signal E2_EN and the driving signal E4_EN, respectively, the second electrode E2 and the fourth electrode E4 each have a voltage difference of 40V (i.e., |V1-V2|) with the first electrode E1 and the third electrode E3. Thus, as shown in FIG. 1B, a horizontal electric field EFh1 closer to the first substrate 101 is formed between the first electrode E1 and the second electrode E2, a horizontal electric field (not shown) closer to the second substrate 102 is formed between the third electrode E3 and the fourth electrode E4, a vertical electric field EFv1 is formed between the first electrode E1 and the fourth electrode E4, and a vertical electric field (not shown) is formed between the second electrode E2 and the third electrode E3. Figure 4

[0078] The horizontal electric fields EFh1 between the first electrode E1 and the second electrode E2 and between the third electrode E3 and the fourth electrode E4 can pull the long axes of the liquid crystal molecules LC originally maintained in the focal conic state 150FC to be arranged in a direction more parallel to the surface of the substrate (e.g., the tilt angle with respect to the surface of the substrate is less than 15 degrees). The vertical electric fields EFv1 between the first electrode E1 and the fourth electrode E4 and between the second electrode E2 and the third electrode E3 can pull the long axes of another portion of the liquid crystal molecules LC originally maintained in the focal conic state 150FC to be arranged in a direction more perpendicular to the surface of the substrate (e.g., the tilt angle with respect to the surface of the substrate is greater than 80 degrees). Unlike the switching voltage 40V in general switching from the focal conic state to the planar state, the simultaneous action of the horizontal electric fields and the vertical electric fields can effectively disturb the cholesteric liquid crystal layer 150 at a lower voltage (e.g., 20V), and the cholesteric liquid crystal layer 150 can be transformed into and maintained in the planar state 150PL after the electrodes are disabled (as shown in FIG. 1C).​Figure 4 and Figure 5 as shown.

[0079] From another point of view, in the present embodiment, the cholesteric liquid crystal panel 10 does not need to be driven to the homeotropic state by a high voltage (e.g. 40V) before it can be switched from the focal conic state 150FC to the planar state 150PL. Therefore, the switching time from the focal conic state 150FC to the planar state 150PL can be effectively reduced, which helps to speed up the update of the display picture.

[0080] Please refer to Figure 5 , Figure 6A and Figure 6B When the cholesteric liquid crystal panel 10 is to be switched from the planar state 150PL (i.e. the second state) to the focal conic state 150FC (i.e. the first state), the first electrode E1, the second electrode E2, the third electrode E3 and the fourth electrode E4 can be enabled in two different time intervals in a time sequence with different driving manners.

[0081] For example, in the process of switching the cholesteric liquid crystal layer 150 from the second state to the first state, in a first time interval TP1 (as shown in Figure 8A ), the first electrode E1 and the third electrode E3 are enabled to have a first voltage V1', the second electrode E2 and the fourth electrode E4 are enabled to have a second voltage V2', and the first voltage V1' is different from the second voltage V2'. More specifically, the polarities of the driving signal E1_EN' applied to the first electrode E1 and the driving signal E3_EN' applied to the third electrode E3 are opposite to the polarities of the driving signal E2_EN' applied to the second electrode E2 and the driving signal E4_EN' applied to the fourth electrode E4, and these driving signals are, for example, alternating current signals with a fixed period.

[0082] For example, in a time interval of a half period, the first voltage V1' can be a positive bias voltage less than 10V, and the second voltage V2' can be a negative bias voltage less than 10V; while in a time interval of another half period, the first voltage V1' can be a negative bias voltage less than 10V, and the second voltage V2' can be a positive bias voltage less than 10V. Therefore, when the first electrode E1 and the third electrode E3 are respectively applied with the same driving signal E1_EN' and the driving signal E3_EN', and the second electrode E2 and the fourth electrode E4 are respectively applied with the same driving signal E2_EN' and the driving signal E4_EN', the second electrode E2 and the fourth electrode E4 each have a voltage difference (i.e. |V1'-V2'|) less than 20V with the first electrode E1 and the third electrode E3. Therefore, as shown in Figure 6AAs shown, a horizontal electric field EFh2closer to the first substrate 101 is formed between the first electrode E1 and the second electrode E2, and a horizontal electric field (not shown) closer to the second substrate 102 is formed between the third electrode E3 and the fourth electrode E4.

[0083] In the first time interval TP1, the horizontal electric field can first disturb the liquid crystal molecules LC originally in the planar state 150PL, especially the liquid crystal molecules LC closer to the first substrate 101 and the second substrate 102, to form a focal conic state arrangement. It is particularly noted that, in order to avoid the cholesteric liquid crystal panel 10 being pressed by external force to make the first substrate 101 and the second substrate 102 close to each other and affect the film thickness uniformity of the cholesteric liquid crystal layer 150, the cholesteric liquid crystal panel 10 can further be provided with a gap object 180. In the embodiment, the gap object 180 can be arranged on the second substrate 102, but is not limited thereto. In another embodiment, the gap object 180 can also be arranged on the first substrate 101.

[0084] Since the liquid crystal molecules LC between the gap object 180 and the first substrate 101 of the cholesteric liquid crystal layer 150 are difficult to be driven by the vertical electric field, even if other parts of the liquid crystal molecules LC are arranged in the focal conic state (i.e. the haze state) by the vertical electric field, the liquid crystal molecules LC overlapping the gap object 180 along the direction D3 are still arranged in the planar state (i.e. the transparent state), which causes the problem of light leakage and contrast reduction.

[0085] Therefore, unlike the known vertical electric field used for switching from the planar state to the focal conic state, the cholesteric liquid crystal panel 10 of the embodiment first disturbs the liquid crystal molecules LC between the gap object 180 and the first substrate 101 of the cholesteric liquid crystal layer 150 by the horizontal electric field in the first time interval TP1, so that the arrangement of the liquid crystal molecules LC can be effectively switched from the planar state to the focal conic state (as shown in FIG. 1C). Figure 6A In other words, the overall haze of the cholesteric liquid crystal panel 10 when maintained in the focal conic state 150FC can be improved, thereby increasing the display contrast.

[0086] Further, in the process of switching the cholesteric liquid crystal layer 150 from the second state to the first state, in the second time interval TP2 (as shown in FIG. 1D), the liquid crystal molecules LC originally in the planar state 150PL are disturbed by the vertical electric field to form a focal conic state arrangement. Figure 8BAs shown, the first electrode E1 and the second electrode E2 are enabled to have a third voltage V3, the third electrode E3 and the fourth electrode E4 are enabled to have a fourth voltage V4, and the third voltage V3 is different from the fourth voltage V4. For example, the third voltage V3 can be a positive bias voltage less than 20V during a time interval of one half cycle, and the third voltage V3 can be a negative bias voltage less than 20V during a time interval of another half cycle. More specifically, the driving signal E1_EN" applied to the first electrode E1 and the driving signal E2_EN" applied to the second electrode E2 are alternating current signals with a fixed period. Unlike the driving signal E1_EN" and the driving signal E2_EN", the driving signal E3_EN" applied to the third electrode E3 and the driving signal E4_EN" applied to the fourth electrode E4 are direct current signals with a fixed potential (e.g. a ground potential).

[0087] Therefore, when the first electrode E1 and the second electrode E2 are respectively applied with the same driving signal E1_EN" and the driving signal E2_EN", and the third electrode E3 and the fourth electrode E4 are respectively applied with the same driving signal E3_EN" and the driving signal E4_EN", the first electrode E1 and the second electrode E2 each have a voltage difference (i.e. |V3-V4|) less than 20V with the third electrode E3 and the fourth electrode E4. Therefore, as shown, the first electrode E1 and the second electrode E2 each form a vertical electric field EFv2 with the third electrode E3 and the fourth electrode E4. Figure 6B

[0088] In the second time interval TP2, the liquid crystal molecules LC between the upper electrode (i.e. the third electrode E3 or the fourth electrode E4) and the lower electrode (i.e. the first electrode E1 or the second electrode E2) are disturbed by the above-mentioned vertical electric field EFv2 to form a focal conic state arrangement (as shown). Figure 6B In the present embodiment, the second time interval TP2 can be after the first time interval TP1, but is not limited thereto. In another variant embodiment, the first time interval TP1 can also be after the second time interval TP2.

[0089] It is particularly noted that, Figure 7 the absolute value of the difference between the first voltage V1 and the second voltage V2 (i.e. |V1-V2|) in Figure 8B is greater than the absolute value of the difference between the third voltage V3 and the fourth voltage V4 (i.e. |V3-V4|) in Figure 8B and the absolute value of the difference between the third voltage V3 and the fourth voltage V4 in Figure 8A is greater than the absolute value of the difference between the first voltage V1' and the second voltage V2' (i.e. |V1'-V2'|) in

[0090] ​Further embodiments will be described below in detail, in which the same components will be denoted by the same reference numerals, and the description of the same technical content will be omitted, and the description of the omitted parts will be referred to the foregoing embodiments, which will not be described below.

[0091] Figure 9 and Figure 10 is a top view of a first electrode, a second electrode, a third electrode and a fourth electrode according to another variant embodiment of the present application. Please refer to Figure 9 , unlike the first electrode E1 to the fourth electrode E4 of Figure 1 , in another variant embodiment, the first electrode E1-A has a first connecting portion E1m1, a second connecting portion E1m2, a plurality of first comb-shaped portions E1c1 and a plurality of first comb-shaped portions E1c2. In this embodiment, the first connecting portion E1m1 and the second connecting portion E1m2 are respectively arranged at opposite sides of the second electrode E2-A, the plurality of first comb-shaped portions E1c1 extend from the first connecting portion E1m1 toward the second electrode E2-A, and the plurality of first comb-shaped portions E1c2 extend from the second connecting portion E1m2 toward the second electrode E2-A.

[0092] On the other hand, the second electrode E2-A has a connecting portion E2m, a plurality of second comb-shaped portions E2c1 and a plurality of second comb-shaped portions E2c2. The plurality of second comb-shaped portions E2c1 extend from the connecting portion E2m toward the first connecting portion E1m1 of the first electrode E1-A. The plurality of second comb-shaped portions E2c2 extend from the connecting portion E2m toward the second connecting portion E1m2 of the first electrode E1-A. More specifically, the plurality of first comb-shaped portions E1c1 of the first electrode E1-A and the plurality of second comb-shaped portions E2c1 of the second electrode E2-A are alternately arranged along the direction D1, and the plurality of first comb-shaped portions E1c2 of the first electrode E1-A and the plurality of second comb-shaped portions E2c2 of the second electrode E2-A are alternately arranged along the direction D1. It is particularly noted that the arrangement positions of the plurality of first comb-shaped portions E1c1 in the direction D1 are staggered with the plurality of first comb-shaped portions E1c2, and the arrangement positions of the plurality of second comb-shaped portions E2c1 in the direction D1 are staggered with the plurality of second comb-shaped portions E2c2.

[0093] Please refer to Figure 10 , similarly, the fourth electrode E4-A has a first connecting portion E4m1, a second connecting portion E4m2, a plurality of fourth comb-shaped portions E4c1 and a plurality of fourth comb-shaped portions E4c2. In this embodiment, the first connecting portion E4m1 and the second connecting portion E4m2 of the fourth electrode E4-A are respectively arranged at opposite sides of the third electrode E3-A, the plurality of fourth comb-shaped portions E4c1 extend from the first connecting portion E4m1 toward the third electrode E3-A, and the plurality of fourth comb-shaped portions E4c2 extend from the second connecting portion E4m2 toward the third electrode E3-A.

[0094] The third electrode E3-A has a connection portion E3m, a plurality of third comb portions E3cl and a plurality of third comb portions E3c2. The third comb portions E3cl extend from the connection portion E3m toward the first connection portion E4ml of the fourth electrode E4-A. The third comb portions E3c2 extend from the connection portion E3m toward the second connection portion E4m2 of the fourth electrode E4-A. More specifically, the plurality of third comb portions E3cl of the third electrode E3-A and the plurality of fourth comb portions E4cl of the fourth electrode E4-A are alternately arranged along the direction D2, and the plurality of third comb portions E3c2 of the third electrode E3-A and the plurality of fourth comb portions E4c2 of the fourth electrode E4-A are alternately arranged along the direction D2. It is particularly noted that the arrangement positions of the plurality of third comb portions E3cl in the direction D2 are staggered with respect to the plurality of third comb portions E3c2, and the arrangement positions of the plurality of fourth comb portions E4cl in the direction D2 are staggered with respect to the plurality of fourth comb portions E4c2.

[0095] Please refer to Figure 9 and Figure 10 , similar to the first electrode E1 to the fourth electrode E4 of Figure 1 , in this embodiment, the extension directions of the first comb portions E1cl and the first comb portions E1c2 of the first electrode E1-A and the second comb portions E2cl and the second comb portions E2c2 of the second electrode E2-A can intersect (e.g., perpendicular to) the extension directions of the third comb portions E3cl and the third comb portions E3c2 of the third electrode E3-A and the fourth comb portions E4cl and the fourth comb portions E4c2 of the fourth electrode E4-A, respectively.

[0096] Since the first electrode E1-A to the fourth electrode E4-A of this embodiment can be used to replace the first electrode E1 to the fourth electrode E4 of Figure 1 , the driving modes related to these electrodes can refer to the relevant paragraphs of the foregoing embodiments, which will not be repeated here.

[0097] Figure 11 and Figure 12 are top view schematic diagrams of a first electrode, a second electrode, a third electrode and a fourth electrode according to another variant embodiment of the present application. Please refer to Figure 11 , unlike the foregoing embodiments, in this embodiment, the extension directions (e.g., direction D2') of the plurality of first comb portions E1c-B of the first electrode E1-B can be inclined to the extension direction (e.g., direction D1) of the connection portion E1m-B, and the extension directions (e.g., direction D2') of the plurality of second comb portions E2c-B of the second electrode E2-B can be inclined to the extension direction (e.g., direction D1) of the connection portion E2m-B. The alternate arrangement direction (e.g., direction D1') of the plurality of first comb portions E1c-B and the plurality of second comb portions E2c-B is also inclined to the extension direction of the connection portion E1m-B.

[0098] Please refer to Figure 12 Similarly, the extension direction (e.g., direction D1') of the plurality of third comb-like portions E3c-B of the third electrode E3-B can be inclined to the extension direction (e.g., direction D2) of the connection portion E3m-B, and the extension direction (e.g., direction D1') of the plurality of fourth comb-like portions E4c-B of the fourth electrode E4-B can be inclined to the extension direction (e.g., direction D2) of the connection portion E4m-B (or the connection portion E3m-B). The alternating arrangement direction (e.g., direction D2') of the plurality of third comb-like portions E3c-B and the plurality of fourth comb-like portions E4c-B is also inclined to the extension direction (e.g., direction D2) of the connection portion E4m-B (or the connection portion E3m-B).

[0099] Since the first electrode E1-B to the fourth electrode E4-B of the present embodiment can be used to replace the first electrode E1 to the fourth electrode E4 of Figure 1 , the driving mode related to these electrodes can refer to the relevant paragraphs of the foregoing embodiments, which will not be repeated here.

[0100] Figure 13 and Figure 14 is a top view schematic diagram of a first electrode, a second electrode, a third electrode and a fourth electrode according to still another variant embodiment of the present application. Please refer to Figure 13 Unlike the first electrode E1-A and the second electrode E2-A of Figure 9 , the plurality of first comb-like portions extending from the first connection portion E1m1-C or the second connection portion E1m2-C in the first electrode E1-C of the present embodiment can have different extension directions, and the plurality of second comb-like portions extending from the connection portion E2m-C in the second electrode E2-C can have different extension directions.

[0101] For example, the extension direction (e.g., direction D2') of the first comb-like portion E1c11 and the extension direction (e.g., direction D2'') of the first comb-like portion E1c12 extending from the first connection portion E1m1-C intersect with each other and are both inclined to the extension direction (e.g., direction D1) of the first connection portion E1m1-C. The extension direction (e.g., direction D2'') of the first comb-like portion E1c21 and the extension direction (e.g., direction D2') of the first comb-like portion E1c22 extending from the second connection portion E1m2-C intersect with each other and are both inclined to the extension direction (e.g., direction D1) of the second connection portion E1m2-C. It is particularly noted that the first electrode E1-C also has a conical portion E1c3 extending from the first connection portion E1m1-C and a conical portion E1c4 extending from the second connection portion E1m2-C.

[0102] On the other hand, the extension direction (e.g., direction D2') of the second comb-shaped portion E2c11 extending from the connecting portion E2m-C toward the first connecting portion E1m1-C and the extension direction (e.g., direction D2") of the second comb-shaped portion E2c12 intersect each other and are both inclined to the extension direction (e.g., direction D1) of the connecting portion E2m-C. The extension direction (e.g., direction D2") of the second comb-shaped portion E2c21 extending from the connecting portion E2m-C toward the second connecting portion E1m2-C and the extension direction (e.g., direction D2') of the second comb-shaped portion E2c22 intersect each other and are both inclined to the extension direction (e.g., direction D1) of the connecting portion E2m-C.

[0103] Please refer to Figure 14 Unlike Figure 10 The third electrode E3-A and the fourth electrode E4-A, in this embodiment, the plurality of third comb-shaped portions extending from the first connecting portion E3m-C in the third electrode E3-C may have different extending directions, and the plurality of second comb-shaped portions extending from the first connecting portion E4m1-C or the second connecting portion E4m2-C in the fourth electrode E4-C may have different extending directions.

[0104] For example, the extension directions (e.g., direction D1”) of the third comb-shaped portion E3c11 extending from the connecting portion E3m-C toward the first connecting portion E4m1-C and the extension directions (e.g., direction D1’) of the third comb-shaped portion E3c12 intersect each other and are both inclined to the extension direction (e.g., direction D2) of the connecting portion E3m-C. The extension directions (e.g., direction D1’) of the third comb-shaped portion E3c21 extending from the connecting portion E3m-C toward the second connecting portion E4m2-C and the extension directions (e.g., direction D1”) of the third comb-shaped portion E3c22 intersect each other and are both inclined to the extension direction (e.g., direction D2) of the connecting portion E3m-C. It is particularly noteworthy that the third electrode E3-C also has a tapered portion E3c3 extending from the connecting portion E3m-C toward the first connecting portion E4m1-C and a tapered portion E3c4 extending from the connecting portion E3m-C toward the second connecting portion E4m2-C.

[0105] On the other hand, the extension directions (e.g., direction D1”) of the fourth comb-shaped portion E4c11 and the fourth comb-shaped portion E4c12 (e.g., direction D1’) extending from the first connecting portion E4m1-C in the fourth electrode E4-C intersect each other and are both inclined to the extension direction (e.g., direction D2) of the first connecting portion E4m1-C. The extension directions (e.g., direction D1’) of the fourth comb-shaped portion E4c21 and the fourth comb-shaped portion E4c22 (e.g., direction D1”) extending from the second connecting portion E4m2-C in the fourth electrode E4-C intersect each other and are both inclined to the extension direction (e.g., direction D2) of the second connecting portion E4m2-C.

[0106] Since the first to fourth electrodes E1-D to E4-D of the present embodiment can be used to replace the first to fourth electrodes E1 to E4 of the cholesterol liquid crystal panel 10, Figure 1 the driving modes of these electrodes can refer to the relevant paragraphs of the foregoing embodiments, which will not be repeated here.

[0107] Figure 15 is a cross-sectional view of a cholesterol liquid crystal panel according to a second embodiment of the present application. Figure 16 is Figure 15 a top view of part of the film layers of the cholesterol liquid crystal panel. Please refer to Figure 15 and Figure 16 Unlike the cholesterol liquid crystal panel 10 of Figure 3 , the first and second electrodes E1-D and E2-D of the cholesterol liquid crystal panel 20 of the present embodiment belong to different film layers, and the third and fourth electrodes E3-D and E4-D belong to different film layers. For the sake of clarity, Figure 16 only the drawings of the first substrate 101, the first electrode E1-D, the second electrode E2-D, the third electrode E3-D and the fourth electrode E4-D of Figure 15 are shown.

[0108] In detail, the first and third electrodes E1-D and E3-D are surface electrodes, and overlap the second and fourth electrodes E2-D and E4-D along the direction D3. In order to ensure the electrical independence between the first and second electrodes E1-D and E2-D, an insulating layer INS1 can be provided between the first and second electrodes E1-D and E2-D. Similarly, an insulating layer INS2 can be provided between the third and fourth electrodes E3-D and E4-D to ensure the electrical independence between them.

[0109] Since the first to fourth electrodes E1-D to E4-D of the present embodiment can be used to replace the first to fourth electrodes E1 to E4 of the cholesterol liquid crystal panel 10, Figure 1 the driving modes of these electrodes can refer to the relevant paragraphs of the foregoing embodiments, which will not be repeated here.

[0110] In summary, in the cholesterol liquid crystal panel of an embodiment of the present application, a first electrode comprising a plurality of first comb-shaped portions is provided on a first substrate, and a second electrode comprising a plurality of second comb-shaped portions is provided on a second substrate. The extension directions of the first comb-shaped portions intersect the extension directions of the second comb-shaped portions. When the first, second, third and fourth electrodes are enabled, the horizontal and vertical electric fields formed between these electrodes can allow the cholesterol liquid crystal panel to switch between bistable arrangements without driving through an intermediate state. Therefore, the driving voltage required by the cholesterol liquid crystal panel when switching between bistable states can be effectively reduced, and the switching time can also be greatly reduced.

Claims

1. A cholesteric liquid crystal panel, comprising: a first substrate and a second substrate, disposed on top of each other; a first electrode and a second electrode, disposed on the first substrate, electrically independent of each other, the first electrode having a plurality of first comb-shaped portions; a third electrode and a fourth electrode, disposed on the second substrate, electrically independent of each other, the third electrode having a plurality of third comb-shaped portions, wherein the extending directions of the first comb-shaped portions of the first electrode intersect with the extending directions of the third comb-shaped portions of the third electrode; and a cholesteric liquid crystal layer, disposed between the first substrate and the second substrate, adapted to switch between a first state and a second state, wherein the second electrode has a plurality of second comb-shaped portions, the fourth electrode has a plurality of fourth comb-shaped portions, the first comb-shaped portions and the second comb-shaped portions are alternately arranged along a first direction, the third comb-shaped portions and the fourth comb-shaped portions are alternately arranged along a second direction, and the first direction intersects with the second direction, when the first electrode and the third electrode are enabled to have a first voltage V1 and the second electrode and the fourth electrode are enabled to have a second voltage V2, the cholesteric liquid crystal layer switches from the first state to the second state, the first voltage V1 is different from the second voltage V2. 2.The cholesteric liquid crystal panel of claim 1, wherein the first direction is perpendicular to the second direction. 3.The cholesteric liquid crystal panel of claim 2, wherein the first electrode and the second electrode are the same film layer, and the third electrode and the fourth electrode are the same film layer. 4.The cholesteric liquid crystal panel of claim 1, wherein when the first electrode, the second electrode, the third electrode and the fourth electrode are disabled, the cholesteric liquid crystal layer maintains in the second state. 5.The cholesteric liquid crystal panel of claim 1, wherein in a process of switching the cholesteric liquid crystal layer from the second state to the first state, in a first time interval, the first electrode and the third electrode are enabled to have a first voltage V1′ and the second electrode and the fourth electrode are enabled to have a second voltage V2′, the first voltage V1′ is different from the second voltage V2′. 6.The cholesteric liquid crystal panel of claim 5, wherein in a process of switching the cholesteric liquid crystal layer from the second state to the first state, in a second time interval, the first electrode and the second electrode are enabled to have a third voltage V3 and the third electrode and the fourth electrode are enabled to have a fourth voltage V4, the third voltage V3 is different from the fourth voltage V4. 7.The cholesteric liquid crystal panel of claim 6, wherein the absolute value of the difference between the first voltage V1 and the second voltage V2 is greater than the absolute value of the difference between the third voltage V3 and the fourth voltage V4, and the absolute value of the difference between the third voltage V3 and the fourth voltage V4 is greater than the absolute value of the difference between the first voltage V1′ and the second voltage V2′. 8.The cholesteric liquid crystal panel of claim 6, wherein the second time interval is after the first time interval.

9. The cholesteric liquid crystal panel of claim 6, wherein the cholesteric liquid crystal layer is maintained in the first state when the first, second, third and fourth electrodes are disabled.

10. The cholesteric liquid crystal panel of claim 1, wherein the first and second comb-shaped portions each have a first width along the first direction, any two adjacent ones of the first and second comb-shaped portions have a first pitch along the first direction, a sum of the first width and the first pitch is 8 micrometers, the first width is in a range of 3.0 micrometers to 3.2 micrometers, and the first pitch is in a range of 4.8 micrometers to 5.0 micrometers.

11. The cholesteric liquid crystal panel of claim 10, wherein the third and fourth comb-shaped portions each have a second width along the second direction, any two adjacent ones of the third and fourth comb-shaped portions have a second pitch along the second direction, a sum of the second width and the second pitch is 8 micrometers, the second width is in a range of 3.0 micrometers to 3.2 micrometers, and the second pitch is in a range of 4.8 micrometers to 5.0 micrometers.

12. The cholesteric liquid crystal panel of claim 1, wherein the first and second electrodes belong to different film layers, the third and fourth electrodes belong to different film layers, and the first and third electrodes each overlap the second and fourth electrodes.

13. The cholesteric liquid crystal panel of claim 1, wherein the first state is a focal conic state, and the second state is a planar state.

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