Display device and driving method thereof

Abstract

A display device and a driving method thereof, the display device includes an array substrate, a counter substrate and a liquid crystal layer. The array substrate includes a plurality of scan lines, a plurality of data lines and a plurality of pixel electrodes, the scan lines and the data lines are crossed each other, and the pixel electrodes are electrically connected to the data lines. The counter substrate is disposed on the array substrate and includes a common electrode. The liquid crystal layer is disposed between the array substrate and the counter substrate. In a display period, the display device has an update picture area and a maintenance picture area, each scan line located in the update picture area receives a scan signal, and the scan signal is a decreasing voltage, and a voltage difference between each pixel electrode located in the maintenance picture area and the common electrode is less than a liquid crystal driving voltage.

Description

Technical Field

[0001] This invention relates to a display device and its driving method. Background Technology

[0002] Cholesterol liquid crystal displays are a type of liquid crystal display. Cholesterol liquid crystal molecules exhibit two stable states, thus possessing bistable characteristics. This means that cholesterol liquid crystals can maintain their original molecular arrangement without requiring an external driving voltage. However, when the display device is showing only a portion of the image changing while the rest remains unchanged, the scan lines that handle the image change will turn on to provide updated data signals to the pixel electrodes and then turn off. If the data lines in the area where the image remains unchanged intersect with the aforementioned scan lines, they will experience a momentary voltage drop due to the scan lines turning off. This causes an excessively large voltage difference between the pixel electrode and the common electrode in the area where the image remains unchanged and is electrically connected to the aforementioned data lines, leading to liquid crystal transition. This results in the inability to maintain the image's stability, thus affecting display quality. Summary of the Invention

[0003] The present invention provides a display device that can effectively maintain the image in the image area, thereby improving the display quality.

[0004] The display device proposed in at least one embodiment of the present invention includes an array substrate, a counter substrate, and a liquid crystal layer. The array substrate includes multiple scan lines, multiple data lines, and multiple pixel electrodes, which are interleaved. The pixel electrodes are electrically connected to the data lines. The counter substrate is disposed on the array substrate and includes a common electrode. The liquid crystal layer is disposed between the array substrate and the counter substrate. During a display period, the display device has a refresh screen area and a sustain screen area. Each scan line in the refresh screen area receives a scan signal, and the scan signal is a decreasing voltage. The voltage difference between each pixel electrode and the common electrode in the sustain screen area is less than the liquid crystal driving voltage.

[0005] In at least one embodiment of the present invention, the liquid crystal layer comprises cholesterol liquid crystal.

[0006] In at least one embodiment of the present invention, the liquid crystal driving voltage does not exceed 5 volts.

[0007] In at least one embodiment of the present invention, the plurality of scan lines located in the updated screen area are simultaneously turned on and simultaneously turned off.

[0008] In at least one embodiment of the present invention, the decreasing voltage is a stepped decreasing voltage, which includes a starting voltage, an intermediate voltage and a final voltage provided in sequence. The starting voltage is the turn-on voltage of each scan line, the final voltage is the turn-off voltage of each scan line, and the intermediate voltage is less than the turn-on voltage of the scan line and greater than the turn-off voltage of each scan line.

[0009] In at least one embodiment of the present invention, the difference between the starting voltage and the intermediate voltage is less than or equal to the difference between the intermediate voltage and the final voltage.

[0010] In at least one embodiment of the present invention, the intermediate voltage includes a first intermediate voltage and a second intermediate voltage provided in sequence, wherein the difference between the starting voltage and the first intermediate voltage is less than or equal to the difference between the second intermediate voltage and the final voltage.

[0011] The driving method proposed in at least another embodiment of the present invention is applicable to a display device, the display device comprising an array substrate, a counter substrate, and a liquid crystal layer. The array substrate includes multiple scan lines, multiple data lines, and multiple pixel electrodes, the scan lines and data lines being interleaved, and the pixel electrodes being electrically connected to the data lines respectively. The counter substrate is disposed on the array substrate and includes a common electrode. The liquid crystal layer is disposed between the array substrate and the counter substrate. The driving method includes the following steps: During a display period, the display device has an update screen area and a maintain screen area, each scan line located in the update screen area receives a scan signal, and the scan signal is a decreasing voltage; the voltage difference between each pixel electrode and the common electrode located in the maintain screen area is less than the liquid crystal driving voltage.

[0012] In at least another embodiment of the present invention, the plurality of scan lines located in the updated screen area are simultaneously turned on and simultaneously turned off.

[0013] In at least another embodiment of the present invention, the decreasing voltage is a stepped decreasing voltage, which includes a starting voltage, an intermediate voltage and a final voltage provided in sequence. The starting voltage is the turn-on voltage of each scan line, the final voltage is the turn-off voltage of each scan line, and the intermediate voltage is less than the turn-on voltage of the scan line and greater than the turn-off voltage of each scan line. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a display device according to at least one embodiment of the present invention.

[0015] Figure 2 This is a partial cross-sectional schematic diagram of a display device according to at least one embodiment of the present invention.

[0016] Figure 3 This is a waveform diagram of the scanning signal and data signal during display, according to at least one embodiment of the present invention.

[0017] Figure 4 This is a waveform diagram of the scan signal and data signal during display, according to at least another embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures:

[0019] 10: Display device

[0020] 100: Array substrate

[0021] 102: First substrate

[0022] 104: Scan line

[0023] 106: Data cable

[0024] 108: Pixel Electrode

[0025] 110, 110': Scan drive unit

[0026] 120: Data-driven unit

[0027] 200: Opposing substrate

[0028] 202: Second substrate

[0029] 204: Common Electrode

[0030] 300: Liquid Crystal Layer

[0031] FV: Final voltage

[0032] HA: Maintain screen area

[0033] IV: Starting Voltage

[0034] MV: Intermediate voltage

[0035] MV1: First intermediate voltage

[0036] MV2: Second intermediate voltage

[0037] MV3: Third intermediate voltage

[0038] UA: Update screen area

[0039] △V1, △V2, △V3, △V4: Differences Detailed Implementation

[0040] In the following text, to clearly present the technical features of the present invention, the dimensions (e.g., length, width, thickness, and depth) of the elements (e.g., layers, films, substrates, and regions) in the accompanying drawings will be enlarged proportionally, and the number of some elements may be reduced. Therefore, the description and explanation of the embodiments below are not limited to the number of elements in the drawings or the size and shape of the elements, but should cover deviations in size, shape, and both caused by actual manufacturing processes and / or tolerances. For example, a flat surface shown in the drawings may have rough and / or non-linear characteristics, and an acute angle shown in the drawings may be rounded. Therefore, the elements presented in the accompanying drawings of the present invention are primarily for illustration and are not intended to precisely depict the actual shape of the elements, nor are they intended to limit the claims of the present invention.

[0041] Secondly, the use of terms such as “about,” “approximately,” or “substantially” in this invention not only covers explicitly stated numerical values ​​and ranges, but also the permissible deviation range that can be understood by those skilled in the art to which this invention pertains. This deviation range can be determined by the error generated during measurement, which may be caused by limitations of the measurement system or process conditions, for example.

[0042] Furthermore, the spatial relative terms used in this invention, such as "below," "under," "above," and "above," are for the convenience of describing the relative relationship between one element or feature and another, as shown in the figures. The true meaning of these spatial relative terms includes other orientations. For example, when the illustration is rotated 180 degrees vertically, the relationship between one element and another may change from "below" or "under" to "above" or "above." Moreover, the spatial relative descriptions used in this invention should be interpreted in the same way.

[0043] It should be understood that although the present invention may use terms such as "first," "second," and "third" to describe various elements or signals, these elements or signals should not be limited by these terms. These terms are primarily used to distinguish one element from another, or one signal from another. Furthermore, the term "or" as used in this invention may, depending on the specific circumstances, include any combination of one or more of the associated listed items.

[0044] Furthermore, the present invention can be implemented or applied through other different specific embodiments, and the details of the present invention can also be combined, modified and changed in various embodiments based on different viewpoints and applications without departing from the concept of the present invention.

[0045] Figure 1 This is a schematic diagram of a display device 10 according to at least one embodiment of the present invention. Figure 2 This is a partial cross-sectional schematic diagram of a display device 10 according to at least one embodiment of the present invention. Please refer to... Figure 1and Figure 2 The display device 10 includes an array substrate 100, a counter substrate 200, and a liquid crystal layer 300. The array substrate 100 includes multiple scan lines 104, multiple data lines 106, and multiple pixel electrodes 108. The scan lines 104 and data lines 106 are interleaved, and the pixel electrodes 108 are electrically connected to the data lines 106. The counter substrate 200 is disposed on the array substrate 100 and includes a common electrode 204. The liquid crystal layer 300 is disposed between the array substrate 100 and the counter substrate 200.

[0046] Figure 3 This is a waveform diagram of the scan signal and data signal during display, according to at least one embodiment of the present invention. Please refer to... Figure 1 and Figure 3 During the display period, the display device 10 has an update screen area UA and a maintain screen area HA. ​​Each scan line 104 located in the update screen area UA receives a scan signal, and the scan signal is a decreasing voltage. The voltage difference between each pixel electrode 108 located in the maintain screen area HA and the common electrode 204 is less than the liquid crystal driving voltage.

[0047] like Figure 3 As shown by the solid line in the middle, the scan signal received by each scan line 104 in the updated screen area UA is a decreasing voltage, meaning the scan signal is not turned off instantaneously, but gradually decreases until it turns off. Therefore, as... Figure 3 As shown by the dashed line in the middle, the data line 106, which is located in the image maintenance area HA and intersects with the aforementioned scan line 104, will only experience a small voltage drop due to the decreasing voltage of the aforementioned scan line 104. Therefore, the voltage difference between the pixel electrode 108 and the common electrode 204, which are located in the image maintenance area HA and electrically connected to the aforementioned data line 106, is less than the liquid crystal driving voltage, which can effectively maintain the image and thus improve the display quality.

[0048] Please continue reading Figure 1 The display device 10 further includes scan driving units 110 and 110' and a data driving unit 120. The scan driving units 110 and 110' are disposed on opposite sides of the array substrate 100 and electrically connected to scan lines 104 to provide scan signals to the scan lines 104. The data driving unit 120 is disposed on one side of the array substrate 100 located between the aforementioned opposite sides and electrically connected to a data line 106 to provide data signals to the data line 106. However, the present invention is not limited thereto. In other embodiments, the display device 10 may include only one scan driving unit disposed on one side of the array substrate 100. Furthermore, the display device 10 may include two data driving units disposed on opposite sides of the array substrate 100.

[0049] It is worth noting that, such as Figure 1As shown, since the display device 10 includes only one data driving unit 120 disposed on one side of the array substrate 100, the data signal is more easily affected by the scan signal the further away from the data driving unit 120. Therefore, the voltage drop of the data line 106 in the image maintenance area HA located farther from the data driving unit 120 is greater than the voltage drop of the data line 106 in the image maintenance area HA located closer to the data driving unit 120. That is, the voltage difference between the pixel electrode 108 and the common electrode 204 in the image maintenance area HA located farther from the data driving unit 120 is greater than the voltage difference between the pixel electrode 108 and the common electrode 204 in the image maintenance area HA located closer to the data driving unit 120.

[0050] Please continue reading Figure 2 The array substrate 100 further includes a first substrate 102, and the pixel electrode 108 is disposed on the first substrate 102. The opposing substrate 200 further includes a second substrate 202, and the common electrode 204 is disposed on the second substrate 202. In some embodiments, the materials of the first substrate 102 and the second substrate 202 may include quartz, glass, polymer materials, or other suitable materials. The material of the pixel electrode 108 may include a conductive material. In this embodiment, the material of the pixel electrode 108 includes a transparent conductive material, but the present invention is not limited thereto. The transparent conductive material may be, for example, indium tin oxide, indium zinc oxide, indium gallium zinc oxide, aluminum zinc oxide, other suitable materials, or a single layer, multiple layers, or combination of the aforementioned materials. The material of the common electrode 204 may include a transparent conductive material, such as indium tin oxide, indium zinc oxide, indium gallium zinc oxide, aluminum zinc oxide, other suitable materials, or a single layer, multiple layers, or combination of the aforementioned materials.

[0051] In some embodiments, the liquid crystal layer 300 may contain cholesteric liquid crystal. Since cholesteric liquid crystal can maintain its original liquid crystal molecule arrangement without requiring an external driving voltage, the image can remain unchanged by ensuring that the voltage difference between the pixel electrode 108 and the common electrode 204 located in the image maintenance area HA is less than the liquid crystal driving voltage. Furthermore, the liquid crystal driving voltage does not exceed approximately 5 volts, but this invention is not limited thereto.

[0052] In some embodiments, the materials of the scan line 104 and the data line 106 may include metals, alloys, transparent conductive materials, other suitable materials, or single layers, multiple layers, or combinations of the aforementioned materials. Metals include, for example, aluminum, molybdenum, titanium, copper, or silver; alloys include, for example, alloys of the aforementioned metals; and transparent conductive materials include, for example, indium tin oxide, indium zinc oxide, indium gallium zinc oxide, or aluminum zinc oxide.

[0053] Please continue reading Figure 3 ,like Figure 3The scan signal shown in the solid line is a decreasing voltage, such as a stepped decreasing voltage. The stepped decreasing voltage includes a starting voltage IV, an intermediate voltage MV, and a final voltage FV provided in sequence. The starting voltage IV is the turn-on voltage of each scan line 104, and the final voltage FV is the turn-off voltage of each scan line 104. The intermediate voltage MV is less than the turn-on voltage of each scan line 104 and greater than the turn-off voltage of each scan line 104.

[0054] In some embodiments, the scan lines 104 located in the updated screen area UA are approximately simultaneously turned on and off. Since the simultaneous on and off of multiple scan lines 104 has a more significant impact on the data line 106, the scan signal received by the aforementioned scan lines 104 is a decreasing voltage. This effectively mitigates the situation of a sudden large voltage drop in the data line 106, maintaining the screen display and thus improving display quality. Furthermore, the turn-on voltage of the scan lines 104 can be approximately 20 volts, and the turn-off voltage can be approximately -25 volts, but the present invention is not limited thereto.

[0055] In some embodiments, the difference ΔV1 between the initial voltage IV and the intermediate voltage MV can be less than or equal to the difference ΔV2 between the intermediate voltage MV and the final voltage FV. For example, when the intermediate voltage MV is approximately 0 volts, the difference ΔV1 between the initial voltage IV and the intermediate voltage MV is less than the difference ΔV2 between the intermediate voltage MV and the final voltage FV. Through the aforementioned voltage difference design, an excessively large voltage difference between the initial voltage IV and the intermediate voltage MV can be avoided, preventing a momentary voltage drop in the data signal, thus maintaining a stable image and improving display quality. Furthermore, although the scan drive units 110 and 110' provide a stepped decreasing voltage when providing the scan signal, the measured waveform is not necessarily a stepped decreasing waveform; it can also be a curved decreasing waveform.

[0056] Figure 4 This is a waveform diagram of the scan signal and data signal during display, according to at least another embodiment of the present invention. Please refer to... Figure 4 , Figure 4 Implementation examples and Figure 3 The parts with the same reference numerals in the embodiments have the same technical features, so the same technical features will not be described again here. Figure 4 Implementation examples and Figure 3 The main difference in the embodiments is that the intermediate voltage MV includes a first intermediate voltage MV1 and a second intermediate voltage MV2 provided in sequence, and the difference ΔV1 between the starting voltage IV and the first intermediate voltage MV1 can be less than or equal to the difference ΔV2 between the second intermediate voltage MV2 and the final voltage FV.

[0057] Furthermore, the intermediate voltage MV also includes a third intermediate voltage MV3 provided after the first intermediate voltage MV1 and before the second intermediate voltage MV2. The difference ΔV1 between the starting voltage IV and the first intermediate voltage MV1 can be less than or equal to the difference ΔV3 between the first intermediate voltage MV1 and the third intermediate voltage MV3. The difference ΔV3 between the first intermediate voltage MV1 and the third intermediate voltage MV3 can be less than or equal to the difference ΔV4 between the third intermediate voltage MV3 and the second intermediate voltage MV2. The difference ΔV4 between the third intermediate voltage MV3 and the second intermediate voltage MV2 can be less than or equal to the difference ΔV2 between the second intermediate voltage MV2 and the final voltage FV. It should be understood that, although Figure 4 Three intermediate voltages are shown, but the invention is not limited thereto. In other embodiments, the number of intermediate voltages may be increased or decreased as needed.

[0058] In some embodiments, when the first intermediate voltage MV1 is approximately 0 volts, the difference ΔV1 between the initial voltage IV and the first intermediate voltage MV1 may be less than the difference ΔV2 between the second intermediate voltage MV2 and the final voltage FV, the difference ΔV3 between the first intermediate voltage MV1 and the third intermediate voltage MV3, and the difference ΔV4 between the third intermediate voltage MV3 and the second intermediate voltage MV2.

[0059] When the third intermediate voltage MV3 is approximately 0 volts, the difference ΔV1 between the initial voltage IV and the first intermediate voltage MV1 can be less than the difference ΔV2 between the second intermediate voltage MV2 and the final voltage FV and the difference ΔV4 between the third intermediate voltage MV3 and the second intermediate voltage MV2, and the difference ΔV3 between the first intermediate voltage MV1 and the third intermediate voltage MV3 can be less than the difference ΔV2 between the second intermediate voltage MV2 and the final voltage FV and the difference ΔV4 between the third intermediate voltage MV3 and the second intermediate voltage MV2.

[0060] When the second intermediate voltage MV2 is approximately 0 volts, the difference between the initial voltage IV and the first intermediate voltage MV1, the difference between the first intermediate voltage MV1 and the third intermediate voltage MV3, and the difference between the third intermediate voltage MV3 and the second intermediate voltage MV2, ΔV1, can be less than the difference between the second intermediate voltage MV2 and the final voltage FV, ΔV2.

[0061] By designing the voltage difference relationship described above, it is possible to avoid an excessive voltage difference between the starting voltage IV, the first intermediate voltage MV1, the third intermediate voltage MV3, and the second intermediate voltage MV2, which could cause an instantaneous voltage drop in the data signal, thereby maintaining the image and improving display quality.

[0062] In summary, in the display device and driving method of at least one embodiment of the present invention, since the scanning signal received by the scan line located in the update screen area is a decreasing voltage, that is, the scanning signal is not turned off instantaneously, but gradually decreases to turn off. Therefore, the data line located in the maintenance screen area and intersecting with the aforementioned scan line will only experience a small voltage drop due to the decreasing voltage of the aforementioned scan line. Thus, the voltage difference between the pixel electrode and the common electrode located in the maintenance screen area and electrically connected to the aforementioned data line is less than the liquid crystal driving voltage, which can effectively maintain the screen unchanged, thereby improving the display quality.

[0063] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains may make some changes and modifications without departing from the concept and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A display device, comprising: An array substrate includes multiple scan lines, multiple data lines, and multiple pixel electrodes, wherein the scan lines and data lines are interleaved, and the pixel electrodes are electrically connected to the data lines respectively. A pair of opposing substrates, disposed on the array substrate and including a common electrode; and A liquid crystal layer is disposed between the array substrate and the opposing substrate. During a display period, the display device has a refresh screen area and a sustain screen area. Each scan line in the refresh screen area receives a scan signal, and only the scan signal is a decreasing voltage. Data lines in the sustain screen area that intersect with the scan lines experience only a small voltage drop due to the decreasing voltage of the scan lines. The voltage difference between each pixel electrode and the common electrode in the sustain screen area is less than a liquid crystal driving voltage.

2. The display device of claim 1, wherein the liquid crystal layer comprises cholesteric liquid crystal.

3. The display device as claimed in claim 1, wherein the liquid crystal driving voltage does not exceed 5 volts.

4. The display device of claim 1, wherein the scan lines located in the updated screen area are simultaneously turned on and simultaneously turned off.

5. The display device of claim 1, wherein the decreasing voltage is a stepped decreasing voltage, the stepped decreasing voltage including a starting voltage, an intermediate voltage and a final voltage provided sequentially, wherein the starting voltage is the turn-on voltage of each scan line, the final voltage is the turn-off voltage of each scan line, and the intermediate voltage is less than the turn-on voltage of each scan line and greater than the turn-off voltage of each scan line.

6. The display device of claim 5, wherein the difference between the starting voltage and the intermediate voltage is less than or equal to the difference between the intermediate voltage and the final voltage.

7. The display device of claim 6, wherein the intermediate voltage includes a first intermediate voltage and a second intermediate voltage provided sequentially, and the difference between the starting voltage and the first intermediate voltage is less than or equal to the difference between the second intermediate voltage and the final voltage.

8. A driving method applicable to a display device, the display device comprising an array substrate, a pair of opposing substrates, and a liquid crystal layer, wherein the array substrate includes a plurality of scan lines, a plurality of data lines, and a plurality of pixel electrodes, the scan lines and the data lines interleaving each other, the pixel electrodes being electrically connected to the data lines respectively, wherein the opposing substrate is disposed on the array substrate and includes a common electrode, wherein the liquid crystal layer is disposed between the array substrate and the opposing substrate, and the driving method comprising: During a display period, the display device has an update screen area and a sustain screen area, wherein each scan line in the update screen area receives a scan signal, and only the scan signal is a decreasing voltage, wherein the data lines in the sustain screen area that intersect with the scan lines are affected by the decreasing voltage of the scan lines and only experience a small voltage drop, wherein the voltage difference between each pixel electrode and the common electrode in the sustain screen area is less than a liquid crystal driving voltage.

9. The driving method of claim 8, wherein the scan lines located in the updated screen area are simultaneously turned on and simultaneously turned off.

10. The driving method of claim 8, wherein the decreasing voltage is a stepped decreasing voltage, the stepped decreasing voltage including a starting voltage, an intermediate voltage and a final voltage provided sequentially, wherein the starting voltage is the turn-on voltage of each scan line, the final voltage is the turn-off voltage of each scan line, and the intermediate voltage is less than the turn-on voltage of each scan line and greater than the turn-off voltage of each scan line.

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