Cholesteric liquid crystal display module and driving method thereof

Abstract

The application discloses a cholesteric liquid crystal display module and a driving method thereof, and belongs to the technical field of electronic paper display. The display module comprises a first substrate, a plurality of source driving lines and arrayed pixel electrodes driven by the plurality of source driving lines are arranged on the first substrate; a second substrate is arranged opposite to the first substrate, an alternating common electrode layer is arranged on the second substrate, the alternating common electrode layer comprises a first alternating common electrode area and a second alternating common electrode area which are electrically isolated from each other; a cholesteric liquid crystal layer is sealed between the first substrate and the second substrate; and a conductive frame glue comprises a first conductive part corresponding to the first alternating common electrode area and a second conductive part corresponding to the second alternating common electrode area, and the first conductive part and the second conductive part are electrically isolated from each other. The cholesteric liquid crystal display module and the driving method thereof reduce the number of driving chips and the cost of the module by alternating common electrode partitioning and source line multiplexing.

Description

Technical Field

[0001] This invention relates to the field of electronic paper display technology, and in particular to a cholesteric liquid crystal display module and its driving method. Background Technology

[0002] Cholesteric liquid crystal (ChLC) is a liquid crystal material with a helical molecular structure. Due to its unique bistable properties and reflective display principle, it has broad application prospects in fields such as electronic paper, outdoor signage, and low-power displays.

[0003] Cholesteric liquid crystals can exhibit various molecular arrangement states under different electric field conditions, mainly including the following three:

[0004] Planar State (P-state): The helical axis of the liquid crystal molecules is perpendicular to the substrate surface, forming a complete helical structure. This structure produces Bragg reflection of light of a specific wavelength, resulting in vibrant colors. Cholesteric liquid crystals naturally exhibit this state in the absence of an external electric field or under a weak electric field.

[0005] Focal Conic State (FC State): The helical axes of liquid crystal molecules are disordered, resulting in strong scattering of incident light and a cloudy, opaque, or weakly white appearance. This state can be transitioned from the planar state by applying an appropriate, moderately strong pulsed electric field.

[0006] Homeotropic State (H-state): Liquid crystal molecules are aligned perpendicular to the substrate surface, the helical structure is broken, and a transparent state is achieved. This state is usually formed under the influence of a strong electric field or a surface vertical alignment layer.

[0007] Utilizing the bistable nature of cholesteric liquid crystals, display devices can maintain either a planar state (reflective state) or a focal conic state (scattering state) for extended periods without an electric field, thus achieving ultra-low power consumption displays. However, a single layer of cholesteric liquid crystal cannot simultaneously display black and white—the planar state exhibits colored reflection, and the focal conic state exhibits scattering, but pure black cannot be achieved. Therefore, in practical applications, multi-layer liquid crystal stacking is required to achieve black-and-white or color displays.

[0008] Currently, common cholesteric black and white display modules use a two-layer structure: a cyan layer and a red layer are superimposed, and black and white display is achieved through the principle of color mixing; color display modules use a three-layer structure: red, green and blue layers are superimposed. Figure 1 The structure of a conventional cholesteric single-module display is shown. In this structure, each layer requires an independent driver chip (including a source driver IC and a gate driver IC), so the number of driver ICs required for a single display module is a multiple of the number of layers. Figure 2The conventional cholesteric phase module stacking structure is shown. Taking a dual-layer monochrome module as an example, each layer has 2 source driver ICs. A dual-layer stacked screen requires 4 source driver ICs, and a triple-layer stacked screen requires 6 source driver ICs.

[0009] The cost of driver ICs accounts for a significant proportion of the overall BOM cost of a display module, especially for large-size or high-resolution displays, where the number and cost of driver ICs are even more pronounced. Currently, there is no cholesteric display module structure or driving method that can effectively reduce the number of driver ICs.

[0010] Therefore, how to reduce the number of driver ICs in cholesteric display modules, thereby reducing the module manufacturing cost, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0011] To address the technical problems existing in the background art, this invention proposes a cholesteric liquid crystal display module and its driving method.

[0012] The present invention proposes a cholesteric liquid crystal display module, comprising:

[0013] A first substrate, wherein a plurality of source driving lines and an array of pixel electrodes driven by the plurality of source driving lines are provided on the first substrate;

[0014] The second substrate is disposed opposite to the first substrate, and an AC common electrode layer is provided on the second substrate. The AC common electrode layer includes a first AC common electrode region and a second AC common electrode region that are electrically isolated from each other.

[0015] A cholesteric liquid crystal layer is sealed between the first substrate and the second substrate;

[0016] The conductive frame adhesive includes a first conductive part that is conductive to a first AC common polarity region and a second conductive part that is conductive to a second AC common polarity region, wherein the first conductive part and the second conductive part are electrically isolated from each other;

[0017] Each of the multiple source driving lines is electrically connected to both a first group of pixel electrodes located within the coverage area of ​​the first AC common region and a second group of pixel electrodes located within the coverage area of ​​the second AC common region.

[0018] Preferably, the first AC common pole region and the second AC common pole region are two regions that are equally divided along the direction of the AC common pole layer along its signal input terminal, and the areas of the first AC common pole region and the second AC common pole region are equal.

[0019] Preferably, the first conductive portion and the second conductive portion are electrically connected to the printed circuit board that provides the drive signal through the fan-out trace area on the second substrate.

[0020] Preferably, the first substrate is a thin-film transistor array substrate.

[0021] Preferably, the array of pixel electrodes includes a plurality of pixel electrodes arranged in a matrix, wherein the first group of pixel electrodes and the second group of pixel electrodes correspond to different columns of the matrix, respectively.

[0022] The present invention proposes a driving method for a cholesteric liquid crystal display module, applicable to the cholesteric liquid crystal display module as described in any of the above claims, the method comprising the following steps:

[0023] Based on the image to be displayed, generate first region image data corresponding to the first AC common pole region and second region image data corresponding to the second AC common pole region;

[0024] A first reset signal is output to the first AC common region and the second AC common region, and a second reset signal with the opposite polarity to the first reset signal is output to multiple source drive lines, so that the full-screen cholesteric liquid crystal enters the reflective state;

[0025] Under the condition of outputting a first write signal to the first AC common region and placing the second AC common region in a high-impedance state, the first data signal is output to multiple source drive lines according to the image data of the first region, so as to complete image writing on the first group of pixel electrodes corresponding to the first AC common region.

[0026] Under the condition of outputting a second write signal to the second AC common region and placing the first AC common region in a high-impedance state, a second data signal is output to multiple source drive lines according to the image data of the second region, so as to complete image writing on the second group of pixel electrodes corresponding to the second AC common region.

[0027] Preferably, after the step of bringing the full-screen cholesteric liquid crystal into a reflective state, the method further includes a step of resetting the first reset signal and the second reset signal to zero.

[0028] Preferably, the amplitudes of the first write signal and the second write signal are the same.

[0029] Preferably, both the first data signal and the second data signal include a first signal value for driving the cholesteric liquid crystal into a focal conic state to display black, and a second signal value for driving the cholesteric liquid crystal to maintain a planar state to display white.

[0030] Preferably, the step of generating first region image data corresponding to the first AC common pole region and second region image data corresponding to the second AC common pole region based on the image to be displayed specifically includes:

[0031] Obtain the complete image data of the image to be displayed;

[0032] Based on the preset correspondence between pixel electrodes and AC common electrode regions, the complete image data is divided into first region image data corresponding to the first group of pixel electrodes within the coverage area of ​​the first AC common electrode region, and second region image data corresponding to the second group of pixel electrodes within the coverage area of ​​the second AC common electrode region.

[0033] The cholesteric liquid crystal display module and its driving method proposed in this invention achieve source driver line reuse by dividing the AC common electrode layer into mutually isolated regions and combining them with a driving timing sequence of alternating partition writing. This reduces the number of source driver chips required for a single-layer cholesteric display module by half without increasing the complexity of the driving timing, thus lowering the manufacturing cost of the display module. Simultaneously, by placing the AC common electrode in a high-resistance state in the non-writing regions, mis-driving of the liquid crystal is avoided, ensuring the stable maintenance of the display state during partition writing and guaranteeing display quality and reliability. Furthermore, due to the reduction in the number of driver chips and the suppression of ineffective power consumption by the high-resistance state, the overall power consumption of the module is reduced, and the module size can be further reduced, which is beneficial for achieving a thinner and lighter design. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a conventional cholesteric phase single-module structure in the prior art;

[0035] Figure 2 This is a schematic diagram of a conventional cholesteric phase module stacking structure in the prior art;

[0036] Figure 3 This is a schematic diagram of the display module stacking of one embodiment of the cholesteric liquid crystal display module proposed in this invention;

[0037] Figure 4 This invention provides a global view of a cholesteric liquid crystal display module according to one embodiment. Figure 1 ;

[0038] Figure 5 This invention provides a global view of a cholesteric liquid crystal display module according to one embodiment. Figure 2 ;

[0039] Figure 6 This is a schematic diagram of the working process of a driving method for a cholesteric liquid crystal display module proposed in this invention;

[0040] Figure 7 A schematic flowchart illustrating one embodiment of the driving method for a cholesteric liquid crystal display module proposed in this invention. Figure 1 ;

[0041] Figure 8A schematic flowchart illustrating one embodiment of the driving method for a cholesteric liquid crystal display module proposed in this invention. Figure 2 . Detailed Implementation

[0042] Reference Figures 3-5 The present invention proposes a cholesteric liquid crystal display module, comprising:

[0043] The first substrate has multiple source driving lines and an array of pixel electrodes driven by the multiple source driving lines.

[0044] In this embodiment, the first substrate is a thin-film transistor array substrate.

[0045] The second substrate is disposed opposite to the first substrate, and an AC common electrode layer is provided on the second substrate. The AC common electrode layer includes a first AC common electrode region and a second AC common electrode region that are electrically isolated from each other.

[0046] A cholesteric liquid crystal layer is sealed between the first substrate and the second substrate.

[0047] The conductive frame adhesive includes a first conductive part that is conductive to a first AC common electrode region and a second conductive part that is conductive to a second AC common electrode region, wherein the first conductive part and the second conductive part are electrically isolated from each other.

[0048] Specifically, the conductive frame adhesive is used to connect the AC common electrode layer on the second substrate to the external driving circuit.

[0049] In this configuration, each of the multiple source driving lines is simultaneously electrically connected to both the first group of pixel electrodes located within the coverage area of ​​the first AC common region and the second group of pixel electrodes located within the coverage area of ​​the second AC common region. That is, the same source driving line connects to both the first and second group of pixel electrodes, achieving physical multiplexing of the source driving lines.

[0050] In this embodiment, the first AC common region and the second AC common region are two regions that are equally divided along the direction of the AC common layer along its signal input terminal, and the areas of the first AC common region and the second AC common region are equal.

[0051] Specifically, in order to achieve the reuse of the source drive line, electrical isolation is achieved between the first AC common region and the second AC common region through etching or insulating materials.

[0052] In this embodiment, the first conductive part and the second conductive part are electrically connected to the printed circuit board that provides the drive signal through the fan-out trace area on the second substrate.

[0053] In this embodiment, the array-type pixel electrode includes multiple pixel electrodes arranged in a matrix, with the first group of pixel electrodes and the second group of pixel electrodes corresponding to different columns of the matrix, respectively.

[0054] Specifically, each pixel electrode is electrically connected to the corresponding thin-film transistor, and data signals are provided by the source drive line.

[0055] Specifically, such as Figure 3 As shown, the AC common-polarity layer of a single screen is divided into two regions (the first AC common-polarity region and the second AC common-polarity region) horizontally along the input terminal. The two regions have the same area and are isolated from each other. The conductive frame adhesive is also divided in this direction and is isolated from each other, only conducting with the corresponding AC common-polarity layer. The signal of the AC common-polarity layer is provided by the PCB terminal, led to the perimeter of the screen through the fan-shaped trace area on the screen, and conducted to the second substrate through the conductive frame adhesive. At any given time, only one region of the first AC common-polarity region and the second AC common-polarity region has a charge (positive or negative charge). After the other region discharges to 0 charge, the input terminal remains in a high-impedance state, and the source input lines are multiplexed. For example, pixel electrode S1 is in the first AC common-polarity region, and pixel electrode Sn+1 is in the second AC common-polarity region, while the source drive lines in front of the gates of the two electrodes are in the same group.

[0056] Specifically, such as Figure 4 As shown, since the AC common electrode is divided into two parts, the AC common electrode signal output from the control board is also input into the second substrate from the left and right sides of the screen, from the first substrate.

[0057] Specifically, such as Figure 5 As shown, the original two source chips can be reduced to one through the method of this application. Due to the reduction of chips, flexible boards are used for module design, which can also reduce the size of the module.

[0058] Reference Figures 3-8 The present invention proposes a driving method for a cholesteric liquid crystal display module, applicable to any of the cholesteric liquid crystal display modules described above, the method comprising the following steps:

[0059] S1. Based on the image to be displayed, generate first region image data corresponding to the first AC common pole region and second region image data corresponding to the second AC common pole region.

[0060] In this embodiment, step S1 specifically includes:

[0061] Obtain the complete image data of the image to be displayed;

[0062] Based on the preset correspondence between pixel electrodes and AC common electrode regions, the complete image data is divided into first region image data corresponding to the first group of pixel electrodes within the coverage area of ​​the first AC common electrode region, and second region image data corresponding to the second group of pixel electrodes within the coverage area of ​​the second AC common electrode region.

[0063] Specifically, the complete image data of the image to be displayed is obtained. For example, for a black and white image with a resolution of M×N, its complete image data is an M-row × N-column matrix, where each pixel corresponds to a grayscale value. For example, for a single-layer screen, 0 represents black and 1 represents white.

[0064] Based on the preset correspondence between pixel electrodes and AC common-polarity regions, the complete image data is divided into two subsets. In this embodiment, the display module is horizontally divided, with the first to N / 2 columns of pixel electrodes corresponding to the first AC common-polarity region, and the N / 2+1 to Nth columns of pixel electrodes corresponding to the second AC common-polarity region. Therefore, the first N / 2 columns of the complete image data are extracted as the first region image data, and the last N / 2 columns are extracted as the second region image data.

[0065] This data segmentation function can be implemented by the display controller (TCON) or the main control chip (MCU) through hardware logic or software algorithms. The two segmented data streams are stored in different areas of the frame buffer, or output in a time-division manner.

[0066] S2. Output a first reset signal to the first AC common region and the second AC common region, and output a second reset signal with the opposite polarity to the first reset signal to multiple source drive lines, so that the full-screen cholesteric liquid crystal enters the reflective state.

[0067] In this embodiment, after the step of bringing the full-screen cholesteric liquid crystal into a reflective state, the method further includes the step of resetting the first reset signal and the second reset signal to zero.

[0068] Specifically, the voltage pulse value of the first reset signal is greater than or equal to 15V, and the voltage pulse value of the second reset signal is greater than or equal to -15V.

[0069] In this embodiment, the first reset signal is a +25V voltage pulse applied to the first and second AC common-electrode regions; the second reset signal is a -15V voltage pulse applied to all source drive lines. Under the combined action of the first and second reset signals, a vertical electric field is formed between all pixel electrodes and the AC common-electrode, causing the cholesteric liquid crystal molecules to align vertically. After the electric field is removed, they naturally relax into a planar state (P-state), exhibiting a white reflective state.

[0070] After the reset is complete, the first and second reset signals are returned to zero. In this embodiment, the zeroing is achieved by setting the output voltage to 0V through the driver IC, and maintaining this setting for a sufficient time to allow residual charge to dissipate naturally.

[0071] S3. Under the condition of outputting a first write signal to the first AC common region and placing the second AC common region in a high-impedance state, outputting a first data signal to multiple source drive lines according to the image data of the first region, so as to complete image writing on the first group of pixel electrodes corresponding to the first AC common region.

[0072] In this embodiment, the first write signal is a -2V voltage, which is continuously applied to the first AC common region. The driving channel of the second AC common region is set to a high-impedance state, and there is no effective driving voltage in this region. At this time, although the source driving line outputs data signals to the first group of pixel electrodes and the second group of pixel electrodes simultaneously, because the second AC common region is high-impedance, it cannot form an effective electric field with the pixel electrodes. Therefore, the liquid crystal state of the second AC common region remains unchanged (it is still the white state after reset).

[0073] The first data signal is generated based on the image data of the first region: For pixels that need to display black (image data is 0), the source driving line outputs a +15V voltage pulse, which creates a voltage difference of about 17V between the pixel electrode and the first AC common region (-2V), driving the liquid crystal into the focal cone state (FC state) and presenting a black scattering state; For pixels that need to remain white (image data is 1), the source driving line outputs a 0V voltage, and the voltage difference between the pixel electrode and the first AC common region is only 2V, which is insufficient to change the state of the liquid crystal, and the liquid crystal remains in a planar state (white state).

[0074] S4. Under the condition of outputting a second write signal to the second AC common region and placing the first AC common region in a high-impedance state, outputting a second data signal to multiple source drive lines according to the image data of the second region, so as to complete image writing on the second group of pixel electrodes corresponding to the second AC common region.

[0075] In this embodiment, the amplitudes of the first write signal and the second write signal are the same.

[0076] In this embodiment, both the first data signal and the second data signal include a first signal value for driving the cholesteric liquid crystal into a focal conic state to display black, and a second signal value for driving the cholesteric liquid crystal to maintain a planar state to display white.

[0077] Specifically, the first AC common electrode region switches to a high-resistance state, while the liquid crystal state of the first AC common electrode region remains unchanged, maintaining the black and white image written in step S3. The source drive line outputs a second data signal based on the image data of the second region: +15V for black pixels and 0V for white pixels. The second data signal and the second write signal work together to complete the image writing on the pixel electrode of the second AC common electrode region.

[0078] At this point, the full-screen image refresh is complete. The first and second AC common-pole regions completed image writing at different time intervals, while the source drive line continued to operate throughout the process, achieving multiplexing.

[0079] Specifically, the reuse sequence is as follows:

[0080] First, the screen is fully reset to a reflective state (white state).

[0081] That is, the first and second AC common-pole regions output the same drive signal, but with the polarity opposite to the source drive signal. For example, the AC common-pole drive signal is 25V, and the source drive signal is -15V. After one round of voltage alternation, both the AC common-pole signal and the source signal return to 0, and the entire screen enters the reflection state.

[0082] Then the data writing phase begins:

[0083] Step 1: Write data to the first AC common region and retain it in the second AC common region;

[0084] like Figure 7 As shown, when writing data, data is first written to the pixel electrodes in the first AC common region. During this stage, the AC common drive signal in the first AC common region is -2V, the source signal for writing black pixels is 15V, and the signal for keeping white pixels is 0V. In the second AC common region, since the AC common drive signal is in a high-impedance state, although the pixel electrodes have the same data written in the first AC common region, they cannot form an electric field with the AC common drive signal to act on the liquid crystal. Therefore, all pixels in the second AC common region still retain the reflective state at the time of reset. Then, after alternating the output of AC common and source signal voltages, Step 2 is entered.

[0085] Step 2: Write data to the second AC common region while keeping the first AC common region intact;

[0086] like Figure 8As shown, data is written to the pixel electrodes in the second AC common region. During this stage, the AC common drive signal in the second AC common region is -2V, the source signal for writing black pixels is 15V, and the signal for keeping white pixels is 0V. In the first AC common region, since the AC common drive signal is in a high-impedance state, although the pixel electrodes have the same data written to the second AC common region due to multiplexing, they cannot form an electric field with the AC common drive signal to act on the liquid crystal. Therefore, all pixels in the first AC common region still retain the state written in Step 1. After another round of alternating AC common and source signal voltage outputs, the image is completed.

[0087] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A cholesteric liquid crystal display module, characterized in that, include: A first substrate, wherein a plurality of source driving lines and an array of pixel electrodes driven by the plurality of source driving lines are provided on the first substrate; The second substrate is disposed opposite to the first substrate, and an AC common electrode layer is provided on the second substrate. The AC common electrode layer includes a first AC common electrode region and a second AC common electrode region that are electrically isolated from each other. A cholesteric liquid crystal layer is sealed between the first substrate and the second substrate; The conductive frame adhesive includes a first conductive part that is conductive to a first AC common polarity region and a second conductive part that is conductive to a second AC common polarity region, wherein the first conductive part and the second conductive part are electrically isolated from each other; Each of the multiple source driving lines is simultaneously electrically connected to a first group of pixel electrodes located within the coverage area of ​​the first AC common region and a second group of pixel electrodes located within the coverage area of ​​the second AC common region. The first AC common pole region and the second AC common pole region are two regions that are equally divided along the direction of the AC common pole layer along its signal input terminal, and the areas of the first AC common pole region and the second AC common pole region are equal.

2. The cholesteric liquid crystal display module according to claim 1, characterized in that, The first conductive part and the second conductive part are electrically connected to the printed circuit board that provides the drive signal through the fan-out trace area on the second substrate.

3. The cholesteric liquid crystal display module according to claim 1, characterized in that, The first substrate is a thin-film transistor array substrate.

4. The cholesteric liquid crystal display module according to claim 1, characterized in that, The array-type pixel electrode includes multiple pixel electrodes arranged in a matrix, with the first group of pixel electrodes and the second group of pixel electrodes corresponding to different columns of the matrix, respectively.

5. A driving method for a cholesteric liquid crystal display module, characterized in that, Applied to the cholesteric liquid crystal display module as described in any one of claims 1 to 4, the method comprises the following steps: Based on the image to be displayed, generate first region image data corresponding to the first AC common pole region and second region image data corresponding to the second AC common pole region; A first reset signal is output to the first AC common region and the second AC common region, and a second reset signal with the opposite polarity to the first reset signal is output to multiple source drive lines, so that the full-screen cholesteric liquid crystal enters the reflective state; Under the condition of outputting a first write signal to the first AC common region and placing the second AC common region in a high-impedance state, the first data signal is output to multiple source drive lines according to the image data of the first region, so as to complete image writing on the first group of pixel electrodes corresponding to the first AC common region. Under the condition of outputting a second write signal to the second AC common region and placing the first AC common region in a high-impedance state, a second data signal is output to multiple source drive lines according to the image data of the second region, so as to complete image writing on the second group of pixel electrodes corresponding to the second AC common region.

6. The driving method for the cholesteric liquid crystal display module according to claim 5, characterized in that, After the step of bringing the full-screen cholesteric liquid crystal into a reflective state, the method further includes the step of resetting the first reset signal and the second reset signal to zero.

7. The driving method for the cholesteric liquid crystal display module according to claim 5, characterized in that, The amplitudes of the first write signal and the second write signal are the same.

8. The driving method for the cholesteric liquid crystal display module according to claim 5, characterized in that, Both the first data signal and the second data signal include a first signal value for driving the cholesteric liquid crystal into a focal conic state to display black, and a second signal value for driving the cholesteric liquid crystal to maintain a planar state to display white.

9. The driving method for a cholesteric liquid crystal display module according to claim 5, characterized in that, The step of generating first region image data corresponding to the first AC common pole region and second region image data corresponding to the second AC common pole region based on the image to be displayed specifically includes: Obtain the complete image data of the image to be displayed; Based on the preset correspondence between pixel electrodes and AC common electrode regions, the complete image data is divided into first region image data corresponding to the first group of pixel electrodes within the coverage area of ​​the first AC common electrode region, and second region image data corresponding to the second group of pixel electrodes within the coverage area of ​​the second AC common electrode region.

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