Display device and driving method thereof

Abstract

The invention discloses a display device and a driving method thereof. The display device comprises an array substrate, an opposite substrate and a liquid crystal layer. The array substrate comprises a plurality of scanning lines, a plurality of data lines and a plurality of pixel electrodes, the scanning lines and the data lines are mutually staggered, and the pixel electrodes are electrically connected with the data lines. The opposite substrate is arranged on the array substrate and comprises a common electrode. The liquid crystal layer is arranged between the array substrate and the opposite substrate. During a display period, the display device is provided with a picture updating area and a picture maintaining area, each scanning line in the picture updating area receives a scanning signal, the scanning signal is a decreasing voltage, and the voltage difference between each pixel electrode in the picture maintaining area and the common electrode is smaller than a liquid crystal driving voltage.

Description

Technical Field

[0001] The invention relates to a display device and a driving method thereof. Background Art

[0002] A cholesterol liquid crystal display device is a type of liquid crystal display device. The arrangement of cholesterol liquid crystal molecules has two stable states, so it has a bistable characteristic, that is, the cholesterol liquid crystal does not need an additional driving voltage from the outside to maintain the original arrangement state of the liquid crystal molecules. However, when the display device is in a display period where only part of the screen changes and the other parts of the screen remain unchanged, since the scan line for screen change will be turned on to provide updated data signals to the pixel electrode and then turned off, if the data line located in the area where the screen remains unchanged is interlaced with the aforementioned scan line, it will be affected by the closure of the aforementioned scan line and cause an instantaneous voltage drop, causing the voltage difference between the pixel electrode located in the area where the screen remains unchanged and electrically connected to the aforementioned data line and the common electrode to be too large, causing liquid crystal transition, resulting in the inability to maintain the screen unchanged, thereby affecting the display quality. Summary of the invention

[0003] The present invention provides a display device, which can effectively maintain the picture unchanged in the picture maintenance area, thereby improving the display quality.

[0004] The display device proposed in at least one embodiment of the present invention comprises an array substrate, a counter substrate and a liquid crystal layer. The array substrate comprises a plurality of scan lines, a plurality of data lines and a plurality of pixel electrodes, the scan lines and the data lines are interlaced with each other, and the pixel electrodes are electrically connected to the data lines respectively. The counter substrate is arranged on the array substrate and comprises a common electrode. The liquid crystal layer is arranged between the array substrate and the counter substrate. During a display period, the display device has an update screen area and a maintenance screen area, each scan line located in the update screen area receives a scan signal, and the scan signal is a decreasing voltage, and the voltage difference between each pixel electrode located in the maintenance screen area and the common electrode is less than the liquid crystal driving voltage.

[0005] In at least one embodiment of the present invention, the liquid crystal layer includes cholesteric 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 update frame area are turned on and off simultaneously.

[0008] In at least one embodiment of the present invention, the decreasing voltage is a step-by-step decreasing voltage, which includes a starting voltage, an intermediate voltage, and a final voltage provided in sequence, wherein the starting voltage is a turn-on voltage of each scan line, the final voltage is a 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, a difference between the starting voltage and the intermediate voltage is less than or equal to a 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, and a difference between the start voltage and the first intermediate voltage is less than or equal to a 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, wherein the display device includes an array substrate, an opposing 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, wherein the scan lines and the data lines are interlaced with each other, and the pixel electrodes are electrically connected to the data lines respectively. The opposing substrate is disposed on the array substrate and includes a common electrode. The liquid crystal layer is disposed between the array substrate and the opposing substrate. The driving method includes the following steps. During a display period, the display device has an update screen area and a maintenance screen area, wherein each scan line located in the update screen area receives a scan signal, and the scan signal is a decreasing voltage, and the voltage difference between each pixel electrode located in the maintenance screen area and the common electrode 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 update frame area are turned on and off simultaneously.

[0013] In at least another embodiment of the present invention, the decreasing voltage is a step-by-step decreasing voltage, which includes a starting voltage, an intermediate voltage, and a final voltage provided in sequence, wherein the starting voltage is a turn-on voltage of each scan line, the final voltage is a 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0018] Description of reference numerals:

[0019] 10: Display device

[0020] 100: Array substrate

[0021] 102: First substrate

[0022] 104: Scan Line

[0023] 106: Data line

[0024] 108: Pixel electrode

[0025] 110, 110': scanning drive unit

[0026] 120: Data drive unit

[0027] 200: Opposite substrate

[0028] 202: Second substrate

[0029] 204: Common electrode

[0030] 300: Liquid crystal layer

[0031] FV: Final voltage

[0032] HA: Maintain picture area

[0033] IV: Starting voltage

[0034] MV: Middle 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: Difference DETAILED DESCRIPTION

[0040] In the following text, in order to clearly present the technical features of the present invention, the dimensions (such as length, width, thickness and depth) of the elements (such as layers, films, substrates and regions, etc.) in the drawings will be enlarged in a non-proportional manner, and the number of some elements will be reduced. Therefore, the description and explanation of the embodiments below are not limited to the number of elements in the drawings and the dimensions and shapes presented by the elements, but should cover the dimensions, shapes and deviations of the two caused by actual processes and / or tolerances. For example, the flat surface shown in the drawings may have rough and / or nonlinear features, and the acute angles shown in the drawings may be rounded. Therefore, the elements presented in the drawings of the present invention are mainly for illustration, and are not intended to accurately depict the actual shape of the elements, nor are they intended to limit the claims of the present invention.

[0041] Secondly, the words "about", "approximately" or "substantially" used in the present invention not only cover the numerical values ​​and numerical ranges clearly recorded, but also cover the allowable deviation range that can be understood by technicians in the technical field to which the invention belongs, wherein this deviation range can be determined by the error generated during measurement, and this error is caused by, for example, the limitations of the measurement system or process conditions.

[0042] In addition, the spatial relative terms used in the present invention, such as "below", "under", "above", "on", etc., are for the convenience of describing the relative relationship between one element or feature and another element or feature, as shown in the figure. The true meaning of these spatial relative terms includes other orientations. For example, when the figure is flipped up and down 180 degrees, the relationship between one element and another element may change from "below" or "under" to "above" or "on". In addition, the spatial relative descriptions used in the present invention should also be interpreted in the same way.

[0043] It should be understood that, although the present invention may use the terms "first", "second", "third" and the like to describe various elements or signals, these elements or signals should not be limited by these terms. These terms are mainly used to distinguish one element from another element, or one signal from another signal. In addition, the term "or" used in the present invention may include any one or more combinations of the associated listed items depending on the actual situation.

[0044] In addition, the present invention may be implemented or applied through other different specific embodiments, and the details of the present invention may 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 is a schematic diagram of a display device 10 according to at least one embodiment of the present invention. Figure 2 FIG. 1 is a partial cross-sectional diagram of a display device 10 according to at least one embodiment of the present invention. Figure 1and Figure 2 The display device 10 includes an array substrate 100, an opposite substrate 200 and a liquid crystal layer 300. The array substrate 100 includes a plurality of scan lines 104, a plurality of data lines 106 and a plurality of pixel electrodes 108. The scan lines 104 and the data lines 106 are interlaced with each other, and the pixel electrodes 108 are electrically connected to the data lines 106. The opposite 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 opposite substrate 200.

[0046] Figure 3 FIG. 1 is a waveform diagram of a scan signal and a data signal during a display period of at least one embodiment of the present invention. Figure 1 and Figure 3 During the display period, the display device 10 has an update screen area UA and a maintenance 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 and the common electrode 204 located in the maintenance screen area HA is less than the liquid crystal driving voltage.

[0047] like Figure 3 As shown by the solid line scanning signal in the figure, since the scanning signal received by each scanning line 104 in the update screen area UA is a decreasing voltage, that is, the scanning signal is not turned off instantly, but gradually decreases to turn off. Figure 3 As shown by the dotted data signal in the middle, the data line 106 located in the picture maintenance area HA and intersecting with the aforementioned scan line 104 will only experience a small voltage drop due to the influence of the decreasing voltage of the aforementioned scan line 104. Therefore, the voltage difference between the pixel electrode 108 located in the picture maintenance area HA and electrically connected to the aforementioned data line 106 and the common electrode 204 is smaller than the liquid crystal driving voltage, which can effectively maintain the picture unchanged, thereby improving the display quality.

[0048] Please continue reading Figure 1 , the display device 10 further includes scan driving units 110, 110' and a data driving unit 120. The scan driving units 110, 110' are disposed on opposite sides of the array substrate 100 and are electrically connected to the scan line 104 to provide a scan signal to the scan line 104, and the data driving unit 120 is disposed on one side of the array substrate 100 located between the aforementioned opposite sides and is electrically connected to the data line 106 to provide a data signal to the data line 106, but 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. In addition, 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 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 susceptible to the influence of the scanning signal at a position farther from the data driving unit 120. Therefore, the voltage drop of the data line 106 located in the screen maintenance area HA farther from the data driving unit 120 is greater than the voltage drop of the data line 106 located in the screen maintenance area HA closer to the data driving unit 120, that is, the voltage difference between the pixel electrode 108 and the common electrode 204 located in the screen maintenance area HA farther from the data driving unit 120 is greater than the voltage difference between the pixel electrode 108 and the common electrode 204 located in the screen maintenance area HA 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, and 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 appropriate materials. The material of the pixel electrode 108 may include a conductive material. In the present embodiment, the material of the pixel electrode 108 includes a transparent conductive material, but the present invention is not limited thereto, and 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 a combination of the foregoing 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 a combination of the foregoing materials.

[0051] In some embodiments, the liquid crystal layer 300 may include cholesterol liquid crystal. Since cholesterol liquid crystal can maintain the original arrangement state of liquid crystal molecules without the need for an additional driving voltage from the outside, the voltage difference between the pixel electrode 108 and the common electrode 204 located in the image maintenance area HA is smaller than the liquid crystal driving voltage to achieve the unchanged image. In addition, the liquid crystal driving voltage does not exceed about 5 volts, but the present invention is not limited thereto.

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

[0053] Please continue reading Figure 3 ,like Figure 3As shown in the solid line scanning signal, the scanning signal is a decreasing voltage, for example, it can be a step-by-step decreasing voltage, the step-by-step 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 scanning line 104, the final voltage FV is the turn-off voltage of each scanning line 104, the intermediate voltage MV is less than the turn-on voltage of each scanning line 104 and greater than the turn-off voltage of each scanning line 104.

[0054] In some embodiments, the scan lines 104 located in the update image area UA are turned on and off at about the same time. Since the multiple scan lines 104 are turned on and off at about the same time, the influence on the data line 106 will be more significant, so the scan signal received by the scan line 104 is a decreasing voltage, which can effectively alleviate the situation where the data line 106 has a momentary large voltage drop, so as to maintain the image unchanged, thereby improving the display quality. In addition, the turn-on voltage of the scan line 104 can be about 20 volts, and the turn-off voltage of the scan line 104 can be about -25 volts, but the present invention is not limited thereto.

[0055] In some embodiments, the difference △V1 between the starting voltage IV and the intermediate voltage MV may be less than or equal to the difference △V2 between the intermediate voltage MV and the final voltage FV. For example, when the intermediate voltage MV is equal to about 0 volts, the difference △V1 between the starting voltage IV and the intermediate voltage MV is less than the difference △V2 between the intermediate voltage MV and the final voltage FV, and the aforementioned voltage difference relationship design can avoid the voltage difference between the starting voltage IV and the intermediate voltage MV from being too large to cause the data signal to have an instantaneous voltage drop, so as to maintain the picture unchanged and thus improve the display quality. In addition, although the scan driving units 110 and 110' provide a step-down voltage when providing the scan signal, the measured waveform is not necessarily a step-down waveform, but may also be a curve-down waveform.

[0056] Figure 4 FIG. 1 is a waveform diagram of a scan signal and a data signal during a display period of at least another embodiment of the present invention. Figure 4 , Figure 4 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 repeated here. Figure 4 Examples and Figure 3 The main difference of the embodiment 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 initial 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] In addition, 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 △V1 between the initial voltage IV and the first intermediate voltage MV1 may be less than or equal to the difference △V3 between the first intermediate voltage MV1 and the third intermediate voltage MV3, the difference △V3 between the first intermediate voltage MV1 and the third intermediate voltage MV3 may be less than or equal to the difference △V4 between the third intermediate voltage MV3 and the second intermediate voltage MV2, and the difference △V4 between the third intermediate voltage MV3 and the second intermediate voltage MV2 may be less than or equal to the difference △V2 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 present invention is not limited thereto. In other embodiments, the number of intermediate voltages may be increased or decreased as required.

[0058] In some embodiments, when the first intermediate voltage MV1 is equal to approximately 0 volts, the difference △V1 between the initial voltage IV and the first intermediate voltage MV1 may be smaller than the difference △V2 between the second intermediate voltage MV2 and the final voltage FV, the difference △V3 between the first intermediate voltage MV1 and the third intermediate voltage MV3, and the difference △V4 between the third intermediate voltage MV3 and the second intermediate voltage MV2.

[0059] When the third intermediate voltage MV3 is equal to approximately 0 volts, the difference △V1 between the initial voltage IV and the first intermediate voltage MV1 may be smaller than the difference △V2 between the second intermediate voltage MV2 and the final voltage FV and the difference △V4 between the third intermediate voltage MV3 and the second intermediate voltage MV2, and the difference △V3 between the first intermediate voltage MV1 and the third intermediate voltage MV3 may be smaller than the difference △V2 between the second intermediate voltage MV2 and the final voltage FV and the difference △V4 between the third intermediate voltage MV3 and the second intermediate voltage MV2.

[0060] When the second intermediate voltage MV2 is equal to approximately 0V, the difference ΔV1 between the initial voltage IV and the first intermediate voltage MV1, 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 may be smaller than the difference ΔV2 between the second intermediate voltage MV2 and the final voltage FV.

[0061] The voltage difference relationship design can avoid the voltage difference between the initial voltage IV, the first intermediate voltage MV1, the third intermediate voltage MV3 and the second intermediate voltage MV2 being too large to cause the data signal to have an instantaneous voltage drop, thereby maintaining the picture unchanged and improving the display quality.

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

[0063] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. A person skilled in the art in the technical field to which the present invention belongs may make some changes and modifications without departing from the concept and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A display device, comprising: An array substrate includes a plurality of scan lines, a plurality of data lines and a plurality of pixel electrodes, wherein the scan lines and the data lines are interlaced with each other, and the pixel electrodes are electrically connected to the data lines respectively; a facing substrate, disposed on the array substrate and comprising a common electrode; and A liquid crystal layer is arranged between the array substrate and the counter substrate, wherein during a display period, the display device has an update screen area and a maintenance screen area, wherein each of the scan lines located in the update screen area receives a scan signal, and the scan signal is a decreasing voltage, wherein the voltage difference between each of the pixel electrodes located in the maintenance screen area and the common electrode is less than a liquid crystal driving voltage.

2. The display device as claimed in 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 5V. 4 . The display device as claimed in claim 1 , wherein the scan lines located in the update frame area are turned on and off simultaneously.

5. The display device as described in claim 1, wherein the decreasing voltage is a step-by-step decreasing voltage, and the step-by-step decreasing voltage includes a starting voltage, an intermediate voltage and a final voltage provided in sequence, wherein the starting voltage is a turn-on voltage of each of the scan lines, the final voltage is a turn-off voltage of each of the scan lines, and the intermediate voltage is less than the turn-on voltage of each of the scan lines and greater than the turn-off voltage of each of the scan lines. 6 . The display device as claimed in claim 5 , wherein a difference between the starting voltage and the intermediate voltage is less than or equal to a difference between the intermediate voltage and the final voltage.

7. The display device as claimed in claim 6, wherein the intermediate voltage comprises a first intermediate voltage and a second intermediate voltage provided in sequence, and a difference between the start voltage and the first intermediate voltage is less than or equal to a 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 counter substrate and a liquid crystal layer, wherein the array substrate comprises a plurality of scan lines, a plurality of data lines and a plurality of pixel electrodes, the scan lines and the data lines are interlaced with each other, the pixel electrodes are respectively electrically connected to the data lines, wherein the counter substrate is disposed on the array substrate and comprises a common electrode, wherein the liquid crystal layer is disposed between the array substrate and the counter substrate, and the driving method comprises: During a display period, the display device has an update screen area and a maintenance screen area, wherein each of the scan lines located in the update screen area receives a scan signal, and the scan signal is a decreasing voltage, wherein the voltage difference between each of the pixel electrodes located in the maintenance screen area and the common electrode is less than a liquid crystal driving voltage. 9 . The driving method as claimed in claim 8 , wherein the scan lines located in the update frame area are turned on and off simultaneously.

10. The driving method as described in claim 8, wherein the decreasing voltage is a step-by-step decreasing voltage, and the step-by-step decreasing voltage includes a starting voltage, an intermediate voltage and a final voltage provided in sequence, wherein the starting voltage is a turn-on voltage of each of the scan lines, the final voltage is a turn-off voltage of each of the scan lines, and the intermediate voltage is less than the turn-on voltage of each of the scan lines and greater than the turn-off voltage of each of the scan lines.

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