CN1621928A - Liquid crystal display with adjustable display viewing angle and display method thereof - Google Patents

Abstract

A liquid crystal display with adjustable display visual angle and a display method thereof are provided, wherein the liquid crystal display with adjustable display visual angle comprises a display panel and a data driver. The display panel comprises a plurality of pixel units, and each pixel unit comprises a first sub-pixel and a second sub-pixel. The data driver is used for respectively providing a first driving voltage and a second driving voltage to the first sub-pixel and the second sub-pixel of each pixel unit. When the liquid crystal display is set to operate in the wide viewing angle mode, the first driving voltage and the second driving voltage of each pixel unit are the same pixel voltage; when the liquid crystal display is set to operate in the narrow viewing angle mode, the first driving voltages of a part of the pixel units and the second driving voltages of the rest of the pixel units are gray voltages.

Description

Liquid crystal display with adjustable display viewing angle and display method thereof

technical field

The present invention relates to a liquid crystal display with adjustable display viewing angle and its display method, in particular to a liquid crystal display and its display method capable of adjusting user's required viewing angle by switching voltage signals.

Background technique

With the advancement of technology, consumers have more opportunities to use mobile products with displays in public areas, such as mobile phones, notebook computers, etc., but if consumers want to maintain personal privacy when using in public areas, then They will need a monitor that can adjust the display viewing angle. At present, there are the following three common methods for controlling the viewing angle of liquid crystal displays.

FIG. 1 is a schematic diagram of adjusting the viewing angle of a liquid crystal display by using a louver-type light absorbing plate in the prior art. Referring to FIG. 1, a louver-type light absorbing plate 110 is added in front of a liquid crystal display 100 and arranged in a regular manner. By adjusting the height h of the light absorbing plate 110 itself and the distance 1 between the light absorbing plates 110 , the angle at which the light L emitted by the display 100 enters the viewer's eyes can be limited. Therefore, the light L can only pass through the light absorbing plate 110 within the range of viewing angle θ, and the viewer can see the image; and the light L outside the viewing angle beyond θ will be absorbed by the light absorbing plate 110 .

However, the disadvantage of this viewing angle control method is that the light-absorbing plate 110 must be added to the outside of the display during use, causing inconvenience in use; as part of the light L is absorbed by the light-absorbing plate 110, the display brightness will drop by more than half ; and the adjustment of its viewing angle is to increase or decrease at the same time from left to right, which cannot satisfy the user's diverse needs for viewing angle switching, such as providing only front view and side view user observation.

2A and 2B are schematic diagrams of adjusting the viewing angle of a liquid crystal display using a light scattering layer in the prior art. A light scattering layer 210 with adjustable light scattering properties is added between the parallel backlight Lb and the liquid crystal layer 200. The light scattering layer 210 may contain Polymer Dispersed Liquid Crystal (PDLC). The narrow viewing angle mode and the wide viewing angle mode are determined by adjusting the voltage applied to the light scattering layer 210 . As shown in FIG. 2A , in the narrow viewing angle mode, the light-scattering layer 210 is in a voltage ON state and is transparent, and the backlight Lb keeps passing through the liquid crystal layer 200 in parallel. Therefore, the image can only be observed by an orthographic viewer. As shown in Figure 2B, in the wide viewing angle mode, the light scattering layer 210 is in the voltage non-conductive state OFF, and the scattered light Ls formed by the backlight Lb through the light scattering layer passes through the liquid crystal layer 200, so that observers at various viewing angles can observe to the image.

However, the disadvantage of this viewing angle control method is that when the light-scattering layer 210 is switched to the voltage conduction state ON, the backlight Lb will be partially reflected when passing through the light-scattering layer 210, causing the brightness of the liquid crystal panel to decrease; As mentioned in the example, this viewing angle control method cannot be adjusted according to the viewing angle required by the user, thus limiting the various options for adjusting the viewing angle.

FIG. 3A and FIG. 3B are schematic diagrams of viewing angle control by using an external liquid crystal display to achieve the effect of adjusting the viewing angle in the prior art. By adjusting the alignment direction of the alignment film on the external liquid crystal display, two modes of wide viewing angle and narrow viewing angle are produced. In the narrow viewing angle mode, the observer will see an image 300 when looking straight ahead, as shown in FIG. 3A ; and when the observer looks sideways, he will see an alternate light and dark pattern 310 that covers the displayed image 300 , as shown in FIG. 3B As shown, it is difficult for the observer to recognize the image, thus achieving the effect of adjustable viewing angle.

However, as mentioned in the above three examples, the current LCD structures with adjustable viewing angles must add additional components to the basic display structure, which causes inconvenience and increases costs. In addition, there are disadvantages of decreased brightness and contrast when viewing angles are switched.

Contents of the invention

In view of this, the object of the present invention is to provide a liquid crystal display with adjustable display viewing angle and a display method thereof. Each pixel includes two sub-pixels, which are respectively driven by two thin film transistors (Thin Film Transistor, TFT), and the liquid crystal inversions corresponding to the two sub-pixels differ by 180 degrees. When operating in the wide viewing angle mode, the liquid crystal driving voltages corresponding to the two sub-pixels are the same, and when operating in the narrow viewing angle mode, the liquid crystal corresponding to one sub-pixel is driven to a dark state, and the liquid crystal corresponding to the other sub-pixel is driven to a normal display , the purpose of adjusting the viewing angle can be achieved.

According to the object of the present invention, a liquid crystal display with adjustable display viewing angle is proposed, including a display panel and a data driver. The display panel includes a plurality of pixel units, and each pixel unit includes a first sub-pixel and a second sub-pixel. The data driver is used to respectively provide the first driving voltage and the second driving voltage to the first sub-pixel and the second sub-pixel of each pixel unit. When the liquid crystal display is set to operate in a wide viewing angle mode, the first driving voltage and the second driving voltage of each pixel unit are the same pixel voltage, and when the liquid crystal display is set to operate in a narrow viewing angle mode, some pixels The first driving voltage of the unit is a grayscale voltage and the second driving voltage is a pixel voltage, and the second driving voltage of the remaining pixel units is a grayscale voltage and the first driving voltage is a pixel voltage. Therefore, the purpose of adjusting the viewing angle can be achieved without additional components.

According to the object of the present invention, a display method for adjusting the display viewing angle of a liquid crystal display is proposed. The liquid crystal display includes a display panel, and the display panel includes a plurality of pixel units. Each pixel unit includes a first sub-pixel and a second sub-pixel. The method includes: when the wide viewing angle mode is executed, using a pixel voltage to drive the first sub-pixel and the second sub-pixel of each pixel unit; and when the narrow viewing angle mode is executed, using a grayscale voltage to drive the first sub-pixel of some pixel units A sub-pixel and the second sub-pixels of these partial pixel units are driven by the pixel voltage, the second sub-pixels of the rest of the pixel units are driven by the gray scale voltage and the first sub-pixels of the rest of the pixel units are driven by the pixel voltage.

In order to make the above-mentioned purposes, features, and advantages of the present invention more obvious and understandable, a preferred embodiment is specifically cited below, and in conjunction with the accompanying drawings, the detailed description is as follows:

Description of drawings

FIG. 1 shows a schematic view of adjusting the viewing angle of a liquid crystal display by using a louver-type light absorbing plate in the prior art.

2A and 2B are schematic diagrams of adjusting the viewing angle of a liquid crystal display using a light scattering layer in the prior art.

FIG. 3A and FIG. 3B are schematic diagrams of viewing angle control by using an external liquid crystal display to achieve an adjustable viewing angle effect in the prior art.

FIG. 4A is a top view block diagram of a liquid crystal display according to a preferred embodiment of the present invention.

FIG. 4B shows a partial cross-sectional view of a liquid crystal display according to a preferred embodiment of the present invention.

FIG. 4C is a schematic diagram of liquid crystal molecules driven by a pixel with a pixel voltage and a grayscale voltage according to a preferred embodiment of the present invention.

FIG. 4D is a flowchart of a method for adjusting the viewing angle of a liquid crystal display according to a preferred embodiment of the present invention.

FIG. 4E is a schematic structural diagram of the liquid crystal display in FIG. 4B operating in the wide viewing angle mode.

FIG. 5 shows that when the sub-pixels A and B input the same pixel voltage or only the sub-pixel A or B input the pixel voltage in the wide viewing angle mode, the viewer observes the driving voltage (V) of the display panel 400 from the front or obliquely 30 degrees to the right and is opposite to the display. Four relationship graphs of brightness (%).

FIGS. 6A to 6D are schematic diagrams showing the results when one of the sub-pixels A and B is set in the display state and the other is set in the dark state when the liquid crystal display in FIG. 4B is operated in the narrow viewing angle mode, and the results are observed obliquely at 30 degrees from the front and right.

FIG. 7 shows the relationship between the ideal gray value and the actual observed gray value corresponding to FIG. 5 .

Explanation of reference symbols:

100: display

110, 420, 520: light absorbing plate

200: LCD panel

210: light scattering layer

300: Front view image

310: light and dark graphics

400: liquid crystal display

410: display panel

411: Substrate

412: pixel unit

415, 417: thin film transistor

420: backlight assembly

430: Gate Driver

440: Data Driver

Detailed ways

Referring to Fig. 4A, Fig. 4B and Fig. 4C at the same time, Fig. 4A is a top view block diagram showing a liquid crystal display according to a preferred embodiment of the present invention, and Fig. 4B is a part of a liquid crystal display according to a preferred embodiment of the present invention A schematic cross-sectional view and FIG. 4C is a schematic diagram showing liquid crystal molecules driven by a pixel with a pixel voltage and a grayscale voltage according to a preferred embodiment of the present invention. The liquid crystal display 400 includes a display panel 410 , a backlight assembly 420 , a gate driver 430 and a data driver 440 . The display panel 410 includes a substrate 411 and a plurality of pixel (Pixel) units 412 formed on the substrate 411, and each pixel unit 412 includes a first sub-pixel A and a second sub-pixel B, connected to different thin film transistors 415 and 417 . For example, a liquid crystal display with a resolution of 1024×768 will have (1024×3×2)×768 thin film transistors. The TFTs 415 and 417 are activated by the output voltage Vg of the gate driver 430 to input the driving voltages Va and Vb output from the data driver 440 to the sub-pixels A and B. The driving voltage Va or Vb can be set as a normal pixel voltage (for example, 5V) and a gray voltage (for example, 0V) to activate the sub-pixel A or B to be in a display state or a dark state. In addition, the backlight assembly 420 is used to provide the backlight Lb to the display panel 410 .

Taking a vertical alignment (Vertical Alignment, VA) liquid crystal display as an example, for each pixel unit 412, when the driving voltages Va and Vb of the sub-pixels A and B input by the thin film transistors 415 and 417 are gray voltages (0V) , that is, it is set to a dark state (Dark Mode), and the liquid crystal molecules of the sub-pixels A and B are in a standing state, as shown in the left diagram of FIG. 4C . When the driving voltages Va and Vb input to the sub-pixels A and B by the thin film transistors 415 and 417 are normal pixel voltages (5V), that is, they are set to the display state, and the liquid crystal molecules of the sub-pixels A and B move towards the pixel due to the action of the electric field. The horizontal direction is inclined, and the liquid crystal molecules of the sub-pixels A and B are inclined toward different sides, as shown in the right diagram of FIG. 4C .

Referring to FIG. 4D , it shows a flowchart of a display method for adjusting the viewing angle of a liquid crystal display according to a preferred embodiment of the present invention. Firstly, in step 430 , the wide viewing angle mode operation is performed, including driving the first sub-pixel A and the second sub-pixel B of each pixel unit 412 to be in the display state at the same time with the same pixel voltage. Next, in step 440, the narrow viewing angle mode operation is performed, including driving the first sub-pixels A of some of the pixel units 412 to a dark state by using the gray scale voltage, and driving the second sub-pixels of these some of the pixel units 412 by using the above-mentioned pixel voltage B displays pixel images, and drives the second sub-pixels B of the rest of the pixel units 412 to a dark state with the gray voltage, and drives the first sub-pixels A of the remaining pixel units 412 to display pixel images with the pixel voltage.

Referring to FIG. 4E , it shows a schematic cross-sectional structure diagram of the liquid crystal display operating in the wide viewing angle mode in FIG. 4B . When the liquid crystal display 400 is set to operate in the wide viewing angle mode, the subpixels A and B in each pixel unit 412 are activated with the same pixel voltage, that is, they are set to the display state at the same time. Therefore, the liquid crystal molecules of the subpixels A and B Tilt to different sides. At this moment, for the observer who is looking straight ahead, the backlight Lb can pass through the liquid crystal molecules C1 and C2 of the first sub-pixel A and the second sub-pixel B at the same time and be incident to the eyes of the observer. Therefore, a front-facing viewer can clearly see the image of the display panel 410 . For observers on both sides, part of the backlight Lb received by the eyes of the left and right observers has a certain angle between the directions of the backlight L1 and L2 and the liquid crystal molecules C1 and C2 respectively. Therefore, the backlight Lb can still pass through the liquid crystal molecules C1 or C2 and enter the left or right viewer, so there will be no gray scale inversion effect, so that the viewers on both sides can also clearly see the image.

Of course, the operation mechanism of the wide viewing angle mode is not limited to the arrangement of the sub-pixels A and B. When the sub-pixels A and B are swapped, since the sub-pixels A and B of each pixel unit 412 are driven to the display state, the backlight Lb can still pass through each sub-pixel A and B to reach the eyes of observers with different viewing angles, achieving a wide range of viewing angles. Viewpoint operation purpose.

As shown in curves C1 and C2 in FIG. 5 , it indicates that in wide viewing angle mode operation, sub-pixels A and B are activated with the same pixel voltage, and the observer observes the display panel with a front view and a 30-degree right oblique (0, 30) 410, the relationship curve between pixel driving voltage (V) and display brightness (%). Although the brightness of the display seen by the observer obliquely at 30 degrees to the right is slightly lower than that of the front viewer, there will be no gray scale inversion phenomenon.

Referring to FIG. 6A to FIG. 6D , it shows that when the liquid crystal display in FIG. 4B is operated in the narrow viewing angle mode, one of the sub-pixels A and B is set to the display state and the other is set to the dark state, viewed from the front and right obliquely at 30 degrees Schematic diagram of the results. When the liquid crystal display 400 is set to operate in the narrow viewing angle mode, one of the sub-pixels A and B must be driven in a dark state (the liquid crystal molecules stand straight), while the other is driven with a pixel voltage required to display images. No matter whether the sub-pixel A or B is in the dark state, the observer who is looking up will not notice the difference, because the phase delay for the observer who is looking up is the same, as shown in FIG. 6A and FIG. 6B . However, when we choose sub-pixel A to be in the dark state and sub-pixel B to be in the display state, as shown in Figure 6C, the backlight Lb received by the eyes of a squinted observer obliquely at 30 degrees to the right and the liquid crystal molecules of sub-pixel B form a certain angle , so the image of the display panel 410 can still be seen. As shown in the curve C3 of FIG. 5 , when the driving voltage is 3V, the relative brightness T is about 43%. However, when we select sub-pixel A to be in the display state and sub-pixel B to be in the dark state, as shown in Figure 6D, the backlight Lb received by the eyes of a squinted observer obliquely at 30 degrees to the right is approximately parallel to the liquid crystal molecules of sub-pixel A , so there will be a phenomenon of grayscale inversion, so that the observer on the right will see a dark and unclear image, as shown in curve C4 in Figure 5, when the driving voltage is 3V, the relative brightness T is only 9%.

As mentioned above, for the same observer, such as an observer oblique to the right 30 degrees, the same sub-pixel driving voltage, such as 5V, but since the sub-pixels A and B are set to display state (5V) and dark The way of state (0V) can form the above two situations, thus producing different brightness, that is, different transmittance of backlight Lb, but the brightness seen by the front viewer is consistent, thus providing a viewing angle Adjustable mechanism.

It should be noted that the operation mechanism of the narrow viewing angle mode is not limited to the arrangement of the sub-pixels A and B shown in FIG. 6 . When the sub-pixels A and B are reversely arranged, what the viewer sees is that the liquid crystal molecules of one sub-pixel stand straight (dark state), while the liquid crystal molecules of the other sub-pixel are in a tilted state (display state). The observer obliquely at 30 degrees to the right still sees that the liquid crystal molecules of one sub-pixel stand straight (dark state), and the received backlight Lb forms a certain angle or is approximately parallel to the liquid crystal molecules of another sub-pixel. Apparently, it does not affect the brightness of the display picture seen by the above-mentioned observers looking straight ahead and obliquely at 30 degrees to the right.

Referring to FIG. 7 , it shows a relationship diagram corresponding to the ideal gray value and the actual observed gray value corresponding to FIG. 5 . As shown in FIG. 7 , the X axis is the ideal gray value switched by the driving voltage, and the Y axis is the actual gray value perceived by human eyes. The curve C5 indicates that when both the sub-pixels A and B are driven to the display state, the grayscale value perceived by a front-facing viewer is consistent with the ideal grayscale value. However, for an observer at a right oblique angle of 30 degrees, as shown by the curve C6, the perceived grayscale change is not much different from the ideal grayscale value. However, as shown by the curves C7 and C8, for example, if it is desired to drive to 121 levels now, an observer who only drives sub-pixel B to the display state and is located at 30 degrees to the right will see 150 levels, while only driving sub-pixel A to the display state And an observer at 30 degrees to the right would see magnitude 54. Therefore, as long as part of the pixel units 412 only drive the sub-pixel A to the display state (or dark state), and the rest of the pixel units 412 only drive the sub-pixel B to the display state (or dark state), the observation on both sides The viewer will see a different image, and this has no effect on the observer.

The operation of the liquid crystal display 400 of the present invention in the narrow viewing angle mode is not limited to only driving the first sub-pixels A of some of the pixel units 412 and the second sub-pixels B of the rest of the pixel units 412 with gray voltages. Other driving voltage activation methods are also possible, such as only driving the first sub-pixel (dark state) of the first part of the pixel unit 412 with a grayscale voltage, and driving the second sub-pixel (dark state) of the second part of the pixel unit 412. state), and the first sub-pixels and the second sub-pixels of the rest of the pixel units 412 are in the display state. As long as one of the sub-pixels of some pixel units is activated in the dark state, observers who look up and look sideways will observe images with different brightness, so as to achieve the purpose of narrow viewing angle operation, which does not depart from the technical scope of the present invention.

In addition, when switching to the narrow viewing angle mode operation, because half of the area of the display panel 410 (that is, half of the sub-pixels) is driven to a dark state, the brightness of the display will decrease, so the backlight assembly 420 can be enlarged to operate in the narrow viewing angle mode. The current at the same time is consistent with the brightness when operating in the wide viewing angle mode. In this way, the user will not observe the difference in display brightness.

As mentioned above, although the present invention is described by taking a vertically aligned liquid crystal display as an example, the liquid crystal display of the present invention can also be applied to a twisted nematic (TN) display. As long as each pixel unit is divided into two independent sub-pixels, the two sub-pixels are driven into the display state at the same time when operating in the wide viewing angle mode, and one of the sub-pixels of some pixel units is driven into the dark state when operating in the narrow viewing angle mode , all can produce the effect that the front viewer can see the image but the side viewers can hardly recognize the image, so as to achieve the purpose of adjustable viewing angle, therefore, neither departs from the technical scope of the present invention.

The advantage of the liquid crystal display disclosed in the above-mentioned embodiments of the present invention is that the pixel unit is divided into sub-pixels A and B and driven by different thin film transistors, and the two sub-pixels of each pixel unit can be driven into the display state at the same time, or driven Sub-pixels A or B of some pixel units are in the dark state to provide the required wide viewing angle and narrow viewing angle mode, especially in the narrow viewing angle mode operation, the number of pixel units that only drive sub-pixel A or B to the dark state can be randomly adjusted and position, making it difficult for observers from certain perspectives to discern. Therefore, the purpose of truly adjustable viewing angle can be achieved without additional components during use.

In summary, although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention, any person of ordinary skill in the art, without departing from the spirit and scope of the present invention, can certainly make Various alterations and modifications, therefore, the protection scope of the present invention should be defined by the claims.

Claims (5)

1. A liquid crystal display with an adjustable display viewing angle, comprising: A display panel comprising a plurality of pixel units, each pixel unit comprising a first sub-pixel and a second sub-pixel; and a data driver, the data driver is used to respectively provide a first driving voltage to the first sub-pixel and a second driving voltage to the second sub-pixel; Wherein, when the liquid crystal display is set to operate in a wide viewing angle mode, the first driving voltage and the second driving voltage corresponding to each pixel unit are the same pixel voltage, and when the liquid crystal display is set to a narrow viewing angle In the operation mode, the first driving voltages corresponding to a part of the pixel units are a grayscale voltage, the second driving voltages are the pixel voltage, and the second driving voltages corresponding to the remaining pixel units are a grayscale voltage. voltages and the first driving voltages are the pixel voltages. 2. The liquid crystal display as claimed in claim 1, wherein the first sub-pixel comprises a first thin film transistor and the second sub-pixel comprises a second thin film transistor. 3. The liquid crystal display as claimed in claim 1, further comprising a backlight assembly, wherein a narrow viewing angle mode operating current of the backlight assembly is higher than a wide viewing angle mode operating current of the backlight assembly. 4. The liquid crystal display as claimed in claim 1, wherein the gray scale voltage is 0V. 5. A display method for adjusting the display angle of a liquid crystal display, wherein the liquid crystal display includes a display panel, the display panel includes a plurality of pixel units, and each pixel unit includes a first sub-pixel and a second sub-pixel, the Methods include: Executing a wide viewing angle mode includes driving the first sub-pixel and the second sub-pixel of each pixel unit with a pixel voltage; and Enforces narrow viewing angle modes, including: driving the first sub-pixels of some of the pixel units with a grayscale voltage and driving the second sub-pixels of the part of the pixel units with the pixel voltage; and The rest of the second sub-pixels are driven by the grayscale voltage and the rest of the first sub-pixels are driven by the pixel voltage.

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