WO2022165446A2

WO2022165446A2 - Lcd device

Info

Publication number: WO2022165446A2
Application number: PCT/US2022/022104
Authority: WO
Inventors: Bor-Jen Wu; Chia-Bin TSEN
Original assignee: Wu Bor Jen; Tsen Chia Bin
Priority date: 2021-01-29
Filing date: 2022-03-28
Publication date: 2022-08-04
Also published as: WO2022165446A3

Abstract

This invention provides an LCD display device without color filter thereon. A set of at least RGB LED chips, packaged inside one assembly housing, can be driven independently and provide backlight to a zone of a LCD display panel. The LCD panel includes a lower plate with TFT thereon, an upper plate with a transparent electrode thereon, and a liquid crystal layer between the lower and upper plates. Each pixel includes one TFT only, and the image can be displayed by using zone image display method. Polarizer plates can be a whole plate, zonewise or small pieces paste on the lower plate.

Description

LCD Device

HELD OF THE INVENTION

[0001] The invention relates to a color LCD device, and more particularly to an LCD device without color filter thereon.

BACKGROUND OF THE INVENTION

[0002] A conventional monochromatic LCD(Liquid Crystal Display) device includes a backlight module with only one wavelength or a white light source, and a liquid crystal panel. Liquid crystal in each pixel provides gray level control by TFT(Thin Film Transistor) on the lower plate of the LCD panel, such that light intensity can be controlled in each pixel.

[0003] In order to provide a color LCD, each pixel is divided into three sub-pixels and a color filter is provided for each sub-pixel. Please refer to Figure 1, wherein a conventional liquid crystal panel includes at least an upper plate 10, a lower plate 14, a liquid crystal layer 20 sandwiched by the upper plate 10 and the lower plate 14, an upper polarizer 12, a lower polarizer 16, and a color filter layer 18. A backlight module 30 provides white light to the liquid crystal display panel, and hence an LCD device is provided.

[0004] Compared to the monochromatic LCD display device, the color LCD display device has ultralow usage efficiency of backlight, for the RGB color filters will block at least half intensity of LCD display device. Further, each pixel includes three sub-pixels for RGB, and the resolution is low.

[0005] Sharp developed a multi-primary color(MPC) technology for wide color gamut(WCG). In addition to RGB, a yellow filter is added to a pixel in the LCD display device. Thus, the usage of the backlight is further reduced. Yet another technology includes not only a yellow filter but also a magenta and a cyan filters in each pixel for WCG concerns. This WCG technology results in backlight usage even lower and hence substantially higher power consumption.

[0006] Thus, an invention is necessary to solve the issues mentioned above.

BRIEF SUMMARY OF THE INVENTION

[0007] The object of this invention is to provide a color liquid crystal display device without the need of a color filter. The liquid crystal display device includes a panel and a backlight module for illuminating the panel. The panel includes a lower plate with a plurality of thin film transistors thereon, an upper plate, and a liquid crystal layer between the lower and upper plates. The panel is divided into a plurality of zones and each zone includes a plurality of pixels. The backlight module includes a plurality of LED assembly for illuminating corresponding plurality of zones, and each LED assembly includes at least one red LED chip, one green LED chip, and one blue LED chip. Each zone displaying images is done by using the zone image-display method which includes mixed-color pixel scanning method, single-color pixel scanning method, and single-color image interlaced method. The zone image-display method basically takes the advantage of persistence of vision, such that three primary colors can be displayed in one pixel without sub-pixel. Thus, there is no necessary to divide each pixel into three sub-pixels to display a color image.

[0008] It is an object of this invention to provide a power saving, high backlight utilization, low on/off frequency, and no diffuser film color LCD display panel. Nature dimming function is inherently built because the LED assembly is turned on only at the time interval of any given pixel is due to be on. In this invention, a liquid crystal display device with higher brightness, larger color gamut, better color saturation, lower power consumption can be easily achieved with the application of color LED backlight assembly and the removal of the color filter.

[0009] It is an object of the present invention to provide a color LCD display panel with resolution comparable to that of a microLED display panel while utilizing the current mature TFT LCD manufacturing processes. It is because that there are three sub-pixels to form a color pixel in the conventional LCD display panel, while there is only one pixel needed for a color pixel in this invention.

[0010] Accordingly, the invention provides a color liquid crystal display device, which comprises a liquid crystal display panel with a backlight module for providing lights to the liquid crystal display panel. The liquid crystal display panel includes a lower plate with a plurality of thin film transistors(TFTs) thereon, an upper plate with a transparent electrode thereon, and a liquid crystal layer between the lower and upper plates, wherein an image displayed is divided into a plurality of zones on the liquid crystal display panel. At least one solid-state lighting assembly of the backlight module illuminates one zone of the plurality of zones and includes at least a red solid-state lighting chip, a green solid-state lighting chip and a blue solid-state lighting chip, wherein an image displayed by the liquid crystal display device is a zone image-display method with colors of the image directly from the red solid-state lighting chip, green, and blue solid-state lighting chip. [0011] The liquid crystal display device according to one embodiment of the present invention, the zone image-display method includes a mixed-color pixel scanning method, a single-color pixel scanning method, and a single-color image interlaced method, such that every single pixel in the liquid crystal display device provide red, green, and blue lights to form color images.

[0012] The liquid crystal display device according to one embodiment of the present invention, the mixed-color pixel scanning method includes steps of determining red, green, and blue intensities of all pixels in the zone; and turning on said each pixel completely in sequence in the zone, while the solid-state lighting assembly in sequence emits the determined red, green, and blue intensities synchronously within time of vision persistence.

[0013] The liquid crystal display device according to one embodiment of the present invention, the solid-state lighting assembly provides grey levels large than 8bits.

[0014] The liquid crystal display device according to one embodiment of the present invention, the solid-state lighting assembly is driven by a PWM driving method.

[0015] The liquid crystal display device according to one embodiment of the present invention, the single-color pixel scanning method includes steps of determining red, green, and blue intensities of each pixel in the zone; and turning on said each pixel completely in red/green/blue sequence in pixel-scanning sequence while the solid-state lighting assembly in sequence emits the determined red, green, and blue intensities synchronously in said red/green/blue sequence in pixel-scanning sequence within time frame of persistence of vision.

[0016] The liquid crystal display device according to one embodiment of the present invention, the single-color image interlace method includes steps of determining red, green, and blue intensities of each pixel in the zone; and turning on all pixel, according to the determined grey levels, by using the plurality of TFTs according to the red, green, and blue intensities in red/green/blue sequence while the solid-state lighting assembly emits at full intensity in red/green/blue sequence synchronously within time frame of persistence of vision.

[0017] The liquid crystal display device according to one embodiment of the present invention, a first polarizer is fit to the zone adjacent to the lower plate, and a second polarizer is fit to the upper plate of the liquid crystal panel. [0018] The liquid crystal display device according to one embodiment of the present invention, a transparent resin of the solid-state lighting assembly includes a rough surface.

[0019] The liquid crystal display device according to one embodiment of the present invention, the red, green and blue solid-state lighting chips are miniLED chips.

[0020] The liquid crystal display device according to one embodiment of the present invention, the red, green and blue solid-state lighting chips are flip chip bonded to the assembly.

[0021] The liquid crystal display device according to one embodiment of the present invention, the solid-state lighting assembly includes diffusors to smear out position factors lights from the solid-state lighting assembly.

[0022] The liquid crystal display device according to one embodiment of the present invention, the solid-state lighting assembly includes a white LED chip, a yellow LED chip, a turquoise LED chip, a magenta LED chip, or a cyan LED chip.

[0023] The liquid crystal display device according to one embodiment of the present invention, the liquid crystal includes TN/STN/IPS/MVA.

[0024] The present invention also provides a method for displaying an image, which comprises steps of: providing a liquid crystal display device; determining red, green, and blue intensities of each pixel in the zone; and turning on said each pixel completely in sequence in the zone while the solid-state lighting assembly in sequence emits the determined red, green, and blue intensities synchronously within time of vision persistence. The liquid crystal display device includes a lower plate with a plurality of TFTs thereon, an upper plate with a transparent electrode thereon, and a liquid crystal between the lower and upper plates, wherein the image is divided into a plurality of zones; and a backlight module for providing lights to the liquid crystal display panel, wherein at least one solid-state lighting assembly of the backlight module illuminates one zone of the plurality of zones and includes at least a red solid-state lighting chip, a green solid-state lighting chip and a blue solid-state lighting chip. Colors of the image are shown directly from the red solid-state lighting chip, green, and blue solid-state lighting chip

[0025] The method according to one embodiment of the present invention, the solid-state lighting assembly provides grey levels large than 8bits. [0026] The method according to one embodiment of the present invention, the solid-state lighting assembly is driven by a PWM driving method.

[0027] The method according to one embodiment of the present invention, the solid-state lighting assembly includes diffusors to smear out position factors lights from the solid-state lighting assembly.

[0028] The present invention also provides a method for display an image, which comprises steps of: providing a liquid crystal display device; determining red, green, and blue intensities of all pixels in the zone; and turning on each pixel grey levels by using the plurality of TFTs according to the red, green, and blue intensities in red/green/blue sequence while the solid-state lighting assembly in sequence emits at full intensities in red/green/blue sequence synchronously within time frame of persistence of vision. The liquid crystal display device which includes a lower plate with a plurality of TFTs thereon, an upper plate with a transparent electrode thereon, and a liquid crystal between the lower and upper plates, wherein the image is divided into a plurality of zones; and a backlight module for providing lights to the liquid crystal display panel, wherein at least one solid-state lighting assembly of the backlight module illuminates one zone of the plurality of zones and includes at least a red solid-state lighting chip, a green solid-state lighting chip and a blue solid-state lighting chip with colors of the image directly from the red solid-state lighting chip, green, and blue solid-state lighting chip.

[0029] The method according to one embodiment of the present invention, the solid-state lighting assembly includes diffusors to smear out position factors lights from the solid-state lighting assembly.

[0030] Other advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed descriptions of the preferred embodiments and upon reference to the accompanying drawings in which:

[0032] Figure 1 is a schematic cross-sectional illustration of a conventional liquid crystal display device; [0033] Figure 2A is a schematic top-view illustration of a backlight for a zone of the liquid crystal display device in according to one embodiment of the present invention;

[0034] Figure 2B is a schematic top- view illustration of a backlight for a zone of the liquid crystal display device in according to another embodiment of the present invention;

[0035] Figure 3A is a schematic cross-sectional illustration of a LED assembly backlight for a zone of the liquid crystal display device in according to one embodiment of the present invention;

[0036] Figure 3B is a schematic cross-sectional illustration of a LED assembly backlight for a zone of the liquid crystal display device in according to another embodiment of the present invention;

[0037] Figure 3C is a schematic cross-sectional illustration of a LED assembly backlight for a zone of the liquid crystal display device in according to another embodiment of the present invention;

[0038] Figure 4 is a schematic electronic circuits diagram of a pixel including a thin film transistor and a liquid crystal capacitor in accordance with one embodiment of the present invention;

[0039] Figure 5A is a schematic top-view illustration of a zone on the lower plate of the liquid crystal display panel in according to one embodiment of the present invention;

[0040] Figure 5B is a schematic top-view illustration of a LED assembly illuminating a zone of the lower plate of the liquid crystal display panel in according to the embodiment of the present invention;

[0041] Figure 6A is a schematic top- view illustration of pixels locations of a zone in according to one embodiment of the present invention;

[0042] Figure 6B is a schematic top-view illustration of each gray level on the pixels of the zone in according to the embodiment of the present invention;

[0043] Figures 7A to 7C provide schematic top-view illustrations of operations of each grey level of pixels at various stage in a zone in according to one embodiment of the present invention; [0044] Figure 8 is a schematic illustration of operations of each gray level on the pixels of the zone in a time of vision persistence in according to the embodiment of the present invention;

[0045] Figures 9A to 9C provide schematic top-view illustrations of operations of each grey level of pixels at various stage in a zone in according to another embodiment of the present invention;

[0046] Figure 10 is a schematic illustration of operations of each gray level on the pixels of the zone in a time of vision persistence in according to the embodiment of the present invention;

[0047] Figures 11A to 11C provide schematic top-view illustrations of operations of each grey level of pixels at various stage in a zone in according to another embodiment of the present invention;

[0048] Figure 12 is a schematic illustration of operations of each gray level on the pixels of the zone in a time of vision persistence in according to the embodiment of the present invention;

[0049] Figure 13 is a schematic cross-sectional illustration of a liquid crystal display device in according to one embodiment of the present invention;

[0050] Figure 14 is a schematic cross-sectional illustration of a liquid crystal display device in according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0051] Accordingly, while example embodiments of the invention are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments of the invention to the particular forms disclosed, but on the contrary, example embodiments of the invention are to cover all modifications, equivalents, and alternatives falling within the scope of the invention.

[0052] The following descriptions explain or interpret contents of terms in the present invention, such that embodiments of the present invention can be understood more clearly.

[0053] The term “solid-state lighting device” may include semiconductor lighting device, such as light emitting diodes. [0054] The term “light emitting diode” may refer to the light emitting diode chip, which is not packaged.

[0055] The term “LED assembly” or “LED package” may refer to the LED chip packaged or assembled into a housing or on a board.

[0056] The term “color filter” may refer to the layer, outside the liquid crystal panel, for filtering white lights into red light, green light, and blue light.

[0057] The term “zone image-display method” may refer to an image that can be displayed individually. Hence, each zone will have its own driving devices for controlling backlight device and all pixels of the zone in the liquid crystal display device.

[0058] The term “diffusors” may refer to particles encapsulated inside a light emitting diode assembly, such that light emitted from the light emitting diode chips can be more uniformly mixed.

[0059] The term “diffuser film” may refer to a film for homogenizing intensity of backlight in a liquid crystal display device.

[0060] The term “chip surface roughness” may refer to a rough surface of a light emitting diode chip as compared to that of a flat surface, such that more photons can be extracted out of the light emitting diode chip reducing the amount of total internal reflection. The emitting angle of the light emitting diode chip can also be increased by surface roughness.

[0061] The term “resin surface roughness” may refer to a rough surface on transparent resin of the LED package or assembly. The resin can be epoxy or silicone.

[0062] The term “grey level” may refer to variant intensities from a monochromatic light.

[0063] The term “brightness” may refer to variant intensities from a mixed light.

[0064] The term “emitting intensity” may refer to output power of lights.

[0065] In the drawings, relative dimensions of each component and among every component may be exaggerated for clarity. Within the following description of the drawings the same or like reference numbers refer to the same or like components or entities, and only the differences with respect to the individual embodiments are described.

[0066] This invention provides a color liquid crystal display device without the use of a color filter. All colors can be provided by the backlight module directly. In the liquid crystal display device, a zone is defined by the area that the color and brightness of each pixel are controlled by one LED assembly, wherein a zone may include a plurality of pixels. The liquid crystal in the present invention, in one embodiment, with TFT acts as an on/off switch of each pixel.

[0067] The backlight module in the present invention mainly utilizes solid-state lighting device as backlight source. Current solid-state lighting devices are semiconductor lighting devices, and commercial semiconductor lighting devices are light emitting diodes(LED). In the present invention, mini LEDs are preferred, and the mixed LED colors are displayed directly through the pixels of the LCD display panel. In the present invention, the side dimensions of the miniLED assembly or package can be less than one minimeter. Compared to the conventional color LCD, the colors are determined by the color filter. However, the manufacturing process of the color filter is substantially complex and not stable, so there are some color differences between any two LCD display panels of the same model by the same vendor, even manufactured using the same process. This color difference can be easily noticed in any hypermarket. In the present invention, wavelength of LED, which directly display images, is determined by the epitaxial process, and later probed and sorted. Therefore, the color and brightness uniformity of the LCD display panel can be easily maintained. Thus, any two LCD display panel can demonstrate exactly the same colors.

[0068] In this invention, colors of the LCD display panel are determined by LEDs directly, and color gamut and CRI(Color Rendering Index) are both better than those of the conventional LCD display panel. Colors of the conventional LCD display panels are determined by white backlights and the color filters, no matter the white backlights are provided by CCFL(cold cathode fluorescent lamp) or white LEDs. Hence, color gamut or CRI is limited by the color filter. However, the color gamut is still adversely influenced by the color filter, no matter how the quality of the backlight improves. Hence, the MPC technology is introduced to improve color gamut and CRI at the expense of lowering backlight utilization. In the present invention, the red, green, and blue LEDs directly provide colors and brightness, which reflect the true color of the image. Without the use of color filter not only increases the backlight utilization, but also achieves better color gamut easily.

[0069] In the present invention, a zone is defined by the number of pixels illuminated by the LED backlight assembly, wherein each zone may correspond to a plurality of pixels. For example, a zone may include a 3x3 pixels, 8x6 pixels, or others. Pixels covered by a zone are mainly determined by the LED assembly dimensions, emitting angles, and its distance to the lower plate of the LCD. Each LED assembly includes at least one red LED chip, one green LED chip, and one blue LED chip.

[0070] In the present invention, the image is shown by the zone image-display method within the time frame of vision persistence, which includes two algorithms. The first one is to turn on each pixel completely in a zone in sequence, while the backlight module provides corresponding mixed colors and brightness of each pixel in the same sequence. The liquid crystal response time is shorter in this invention as compared to that of the conventional art. Because conventionally the twist angle of liquid crystal needs to be controlled accurately to have exact grey level, while in this invention, only full on/off is needed. As a result, a smoother image display can be achieved. Further, because grey level of each color is determined by LEDs driven by PWM(Pulse Width Modulation), grey levels can be more than 8 bits (256 levels) compared to that of the conventional LCD display panel. Thus, the LCD display panel can provide grey levels the same or even beyond those of a conventional CRT(Cathode Ray Tube) display device, which is known to be abundant in colors.

[0071] In one embodiment of the present invention, one zone is illuminated by a LED backlight assembly. However, one zone can be illuminated by two or more than two backlight assemblies, if the image in the zone can be displayed within the time frame of vision persistence.

[0072] The other algorithm is to provide a single color once, such as red light, while the liquid crystal panel controls grey level of every pixel. Within the time of vision persistence, the three primary colors are displayed in sequence, and an image is thus shown to human eyes. This algorithm, although only 8 bits grey level similar to that of the conventional LCD display panel, is much easier to display an image due to the fact that one pixel is a color pixel in contrast to the conventional 3 sub-pixel for a color pixel. This invention is better for the embodiment offers much higher resolutions. Compared to the first algorithm, it is challenging to turn on each pixel in sequence within time of vision persistence, when there are too many pixels in a zone. Further, if another color, such as yellow, is added to the backlight, it simply adds an additional loading to TFT control.

[0073] The above driving methods take the advantages of ultra-fast turning on/off of LED assembly. Hence, the LED assembly can be turned on exactly at the time interval corresponding to any given TFT is due to be on in a zone. Moreover, the present invention can be applied to any kind of liquid crystal display, such as TN(Twisted Nematic), STN(Super Twisted Nematic), VA(Vertical Alignment), MAV(Multi-domain Vertical Alignment), IPS(In-Plane Switching), or any other liquid crystal type.

[0074] In the present invention, except for the color filter, many parts used in the conventional art are also used, such as lower plate, LCD, upper plate, polarizers, and so on. In order not to make any ambiguity, this kind of conventional parts in the conventional LCD display panel are used but may not be described in the embodiments and not shown in the drawings.

[0075] The resolution is directly described by pixels per unit length of a LCD display panel. In the present invention, due to there is no color filter, the resolution can easily be three times higher than that of the conventional one, and thus becomes equivalent to that of the microLED display panel. In the current display technologies, there are low yield and low throughput mass-transfer issues yet to resolve for the microLED display.

[0076] Detailed embodiments of the present invention can be described and shown herein with the drawings.

[0077] Please refer to Figure 2A, wherein a top view of a LED assembly is shown. The LED assembly 100 includes a red LED chip 102, a green LED chip 104, and a blue LED chip 106. The red LED chip 102, the green LED chip 104, and the blue LED chip 106 are assembled or packaged together by any conventional bonding methods, such as wire-boning or flip-chip. In the present invention, the combination of grey levels of the red, green, and blue lights inside the LED assembly 100 determines the color and the brightness of each pixel in the zone.

[0078] In one embodiment, miniLED chip is preferred. The miniLED is a mature and commercially available solution compared to microLEDs. The miniLED assembly is larger than a pixel in a conventional LCD display therefore is not suitable to be directly applied to the high-resolution display. However, using miniLEDs as backlight modules is a viable solution for the high-resolution color LCD display panel.

[0079] The dimension of a zone is determined by LED chip sizes, emitting angles of LED assembly, and the required backlight brightness. Adding diffusors to the resin of the LED assembly as well as roughening, the resin surface can both be used to smear out the LED chip position factor and homogenize mixed colors. The LED assembly can be driven by direct current or by PWM(Pulse- Width Modulation), wherein the PWM is preferred. [0080] Please refer to Figure 2B, LED of other colors can also be added in the present invention. For example, a white LED chip 108 in one embodiment can be bonded to the LED assembly 100 to increase contrast. Hence, red, green, blue LED chips and a white light LED chip are provided as a set of backlight assembly. Some other embodiment provides red, green, blue, and yellow(not shown in the drawings) LED chips bonded in a set or an assembly. Not only four LED chips can be bonded in one assembly, other number of chips, such as six LED chips, can be provided as a set, for examples red, green, blue, yellow, magenta, and cyan LED chips. Another embodiment includes a turquoise LED chip with the red, green, and blue LED chips bonded in the assembly.

[0081] Please refer to Figure 3 A, a cross-sectional view of a LED assembly is shown, wherein LED chips 102 and 106 are bonded inside the housing 100. In this embodiment, one important purpose is to provide a large emitting angle and the illuminating area of the LED assembly 100. The emitting angle of a bare LED chip is about 120°, and can be increased by chip surface roughness (not shown) and resin surface roughness 114 of the LED assembly to about 140°. Lights emitted from the LED assembly can be mixed more homogeneously by the diffusors 110, and a uniform large emitting angle can be achieved. The emitting angle can also be modified by adding optical element or changing housing profile. In one embodiment, sizes of a zone is determined by the shape of the housing wall. An inclined sidewall may be designed to increase emitting angles. After the LED chips are bonded to the housing, transparent resin, such as epoxy or silicone, can be added to encapsulate the LED chips. Diffusors are mixed with the transparent resin. In the present invention, it is not necessary to add color conversion materials, such as phosphor or quantum dot, into the transparent resin, because color conversion material is not necessary. Another embodiment is to omit a package process by using a circuit board instead of housing for LED assembly. Please refer to Figure 3B, transparent resin 110 is formed on the board 101 and covering all LED chips. In the embodiment, a COB(Chip On Board) backlight is used in the present invention, wherein a package process can be omitted.

[0082] Even if there are diffusors in the resin, it is still possible that some specific areas are brighter or some colors at some areas which is much stronger in the LED assembly. For example in Figure 3B, the area overlying the red LED chip 102 is more likely to be illuminated with more red lights than any other area of the LED assembly, and thus the mixed lights are not homogeneous enough. Roughening the resin surface 114, as shown in Figure 3C, can further smear out the intensity difference of the LED assembly due to different viewing angles and positions. In this embodiment, this roughness is on the resin instead of LED chips. This solution is critical, because all lights from the corresponding LED chips can be smeared out more uniformly and emitted from the LED assembly 100 homogeneously. For the embodiment as shown in Figure 3A, resin roughness surface can also be applied.

[0083] Please refer to Figure 4, wherein a pixel of LCD display with the electronic circuit diagram of a TFT and a liquid crystal capacitor is shown. In the present invention, similar to the conventional LCD display, the liquid crystal is driven by the TFT. The gate is electrically coupled to the scanning line and receives instructions to turn on/off the TFT, while the source is electrically coupled to the signal line and receives the information to twist the liquid crystal in the liquid crystal capacitor. The drain is electrically coupled to the pixel electrode of the liquid crystal capacitor and provides an electric potential such that liquid crystal between two electrodes of the capacitor will be twisted and aligned in a specific orientation or angle. The other electrode of the liquid crystal capacitor is grounded. Both the electrodes of the liquid crystal capacitor are transparent. In the present invention, there are two ways to drive the liquid crystal; the first is to turn the liquid crystal completely on and off, and grey level of an image is controlled by the backlight module. The other is to turn the liquid crystal to a certain angle and off that matches with a specific grey level, and backlight is at its brightest level. One electrode of the liquid crystal capacitor is electrically coupled to drain of the TFT which located at the lower plate, and the other grounded electrode located at the upper plate.

[0084] Please refer to Figure 5A, wherein a zone is shown in the lower plate of a liquid crystal display panel. A zone covers a plurality of pixels, and each pixel is controlled by a TFT. An example for this embodiment is depicted in Figure 5A. There are 225 pixels composed by a 15x15 array, and the resolution is 225 pixels. In contrast to the conventional liquid crystal display panel with the same array, there are only 5x5 pixels, and the resolution is down to 25 pixels. TFT is located at the top left corner in each pixel, similar to that of a conventional LCD display panel, and the central region is the transparent electrode for controlling liquid crystal capacitor. Furthermore, the liquid crystal display panel(not shown in Figures 5) includes an upper plate and a liquid crystal layer sandwiched between the plates. A transparent electrode is formed on the upper plate as common electrode for the grounded electrode for all liquid crystal capacitor.

[0085] Please refer to Figure 5B, a red LED chip 102, a green LED chip 106, and a blue LED chip 108 are packaged in an assembly and below the zone. In the zone grey levels of all colors are controlled by the red, green, and blue LEDs. An area of a zone can be larger than the area of LED assembly, and the size of the zone depends mainly upon the distance between the LED assembly to the liquid crystal display panel. Because the backlight module will provide mixed color directly from the three primary colors, color saturation or wide color gamut can be greatly improved compared to those using the conventional white light backlight. Brighter image can also be achieved in the present invention. In addition, the MPC technology is not necessary because the three primary colors are provided directly. Even if the MPC technology is applied to the present invention, the backlight utilization is still substantially higher than that of the conventional one.

[0086] Moreover, a small size polarizer, instead of a full size one, can be attached to the emitting surface of each LED assembly. Since the price of a full size polarizer is high, if there is a small defect in it, the whole polarizer must be replaced. While, in the present invention, if a small size polarizer is used to each LED assembly, the manufacturing cost can be increased. Of course, a full size polarizer can still be used if desired to the lower plate of the liquid crystal display panel.

[0087] The zone image display method is used within time of vision persistence. There are three ways to achieve this including the mixed-color pixel scanning method, the single-color pixel scanning method, and the single color image interlaced method.

[0088] First, the mixed-color pixel scanning method is introduced. Each liquid crystal of the corresponding pixel in the zone is completely turned on and off in sequence, while the backlight module in the zone provides a pre-determined color-mix according to the pixel sequence synchronously within time of vision persistence. In this embodiment, when the first pixel of the zone is completely turned on, the mixed back light passes through the corresponding TFT switch. Because all the other pixels in the zone are turned off completely, no light passes through those pixels, and therefore are dark. Because grey levels of the red, green, and blue are provided by the backlight module and thus determine the color and brightness of the first pixel, the grey level of each color is not determined by the liquid crystal. Then the first pixel is turned off completely, the second pixel of the zone is turned on completely with the other pixels remain off, and the backlight module will provide the grey levels of the red, green, and blue of the second pixel. The process continues until all pixels are turned on and off once in the zone. A complete image can be shown if all pixels in a zone can be turned on and off completely in sequence within time of vision persistence. The response time of LED on/off is significantly faster than that of a liquid crystal. The response time of liquid crystal is about 1-2 mini second, while the response time of LED is about 10’⁹ second; therefore the backlight module can always synchronize with the liquid crystal switch. Furthermore, the response time of the liquid crystal is the shortest if it is turned on/off completely, and will be longer if the liquid crystal is turned on with a grey level or partially. For a conventional LCD display panel, motion blur or mura can be a problem if the LC response time is not fast enough. These issues can be solved by the present invention. For the conventional LCD device, even all pixels are turned off completely, some lights can still leak out due liquid crystal can’t completely block the light of the back light module. In the present invention, a dark image can be provided when all LEDs are turned off completely. Even when a specific LCD of a pixel is not turned off completely yet, all the LEDs in the backlight module could have been turned off. This can not only enhance the image contrast but also to enable a fast moving motion film to be displayed without a motion blur.

[0089] In the present invention, no color filter is needed to generate color images or displays. In a conventional LCD display panel, any two displays are very likely to show differences in colors even if they are made of the same manufacturing process, because variations during the color filter manufacturing is inevitable. In order to fix this issue, a compensate driver is provided to correct the differences. Since there is no color filter used in the current invention thus no such variation exists, every panel displays exactly the same color qualities. In addition, the brightness is greatly improved due to no color filter to block backlight.

[0090] Detailed driving methods will be described with the drawings.

[0091] As shown in Figure 6 A, 9 pixels in a zone is illustrated as example for this embodiment. The number of pixels covered by a zone is determined by the dimension and configuration of the LED assembly, and the 9 pixels in the embodiment are provided for clarify. The 9 pixels are denoted as (1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), and (3, 3). In this zone, the 9 pixels represent a portion of an image. Colors and brightness of the 9 pixels will have corresponding grey levels of the three primary colors. Hence, the 9 pixels is determined by grey levels of all colors, such as (Rll, Gil, Bll), (R12, G12, B12), (R13, G13, B13), (R21, G21, B21), (R22, G22, B22), (R23, G23, B23), (R31, G31, B31), (R32, G32, B32), and (R33, G33, B33), as shown in Figure 6B. In conventional LCD display panel, in order to display an image with 9 pixels, total of 81 sub-pixels must be used and operated by 81 TFTs. [0092] Then, please refer to Figure 7A. Firstly, the liquid crystal of the first pixel (1, 1) is turned on completely while the other 8 pixels remain off completely. At the same time, the backlight module of the zone provides grey levels (Rll, G11, B11) corresponding to the first pixel. Then, the first pixel is turned off completely and the backlight module is also turned off. Please notice that LED can be turned on/off very fast, and there is no grey level on/off for the liquid crystal. The three primary colors are determined by the backlight module directly. This reduces not only the loading of the need of precise grey level controls of the liquid crystal, but also resolves the problems caused by slow response of the liquid crystal. Due to all 8 pixels are turned off completely, for humane eyes, only mixed color of grey levels (Rll, Gil, Bll) of pixel (1, 1) can be seen. Please notice that grey levels in this embodiment is controlled by the LEDs only.

[0093] Then, the first pixel (1, 1) is turned off, the second pixel (1, 2) is turned on completely as shown in Figure 7B, and all the other 7 pixels are remained off. At the same time, the backlight module provides grey levels of (R12, G12, B12). For humane eyes, only mixed color of grey levels (R12, G12, B12) is seen at the second pixel (1, 2). Then, the second pixel is turned off completely, and the backlight module is also turned off. The procedure continues until the last pixel (3, 3) within the time frame of persistence of vision. As shown in Figure 7C, only one pixel is turned on at a time and pixels in the zone are turned on once within the time frame of vision persistence.

[0094] Figure 8 illustrates the on/off states of all pixels at different time domain within time of vision persistence. The abscissa is time and the ordinate is the on/off state of each pixel. At the first period, only the first pixel is turned on and the other 8 pixels are turned off. At the second period, only the second pixel is turned on and the other 8 pixels are turned off, and so on to the ninth pixel. The whole sequence must be finished within time of vision persistence. This kind of image display method is similar to the conventional CRT display, wherein an image is scanned in sequence with time of vision persistence.

[0095] However, it is not necessary to turn on/off each pixel in spatial sequence. For example, if the first pixel (1, 1) is turned on first, the fifth pixel (2, 2) can be turned on next. There is a good reason doing so. If the liquid crystal response time is not fast enough, non-neighboring pixels can be turned on in sequence to increase the image contrast. For a zone, with too many pixels therein, this can be a solution. Thus, the on/off state sequence is irrelevant to the pixel spatial arrangement. The only requirement is all pixels in a zone must be turned on once in any sequence within time of vision persistence. [0096] In the present invention, grey levels of the LEDs driven by PWM can be larger than 8 bits, such as 10 bits, 12 bits, or even more than 12 bits. Current LCD display panel can have at least 8 bits grey levels due to the limited twisted angles of the liquid crystal. Thus, for each single color, there are only 256 grey levels(including totally dark and totally bright). Even for the best IPS(In-Plane Switch) technology, there are only 8 bits grey levels available, and only 160K colors can be demonstrated. While, in the present invention, 10 bits (total 1024 grey levels) can be provided easily by using PWM method, and 1 billion colors can be demonstrated. The LED can even be driven up to 12 bit levels (4096 grey levels), 6.8 billion colors can be demonstrated. Such abundant colors are to the levels of the conventional CRT display device.

[0097] Another embodiment to display an image in a zone is to process red grey levels of all pixels, green grey levels of all pixels and then blue grey levels of all pixel. This is the single-color pixel scanning method, which scans a single color at one time till all colors are scanned within time of vision persistence.

[0098] Similar to the example of the previous embodiment, there are 9 pixels in a zone, as shown in Figure 9A, and grey levels of all pixels are determined first. Then, the first pixel (1, 1) is turned on while the backlight module only provides the corresponding red grey level (R11, 0, 0) of the first pixel. In this embodiment, the backlight will not provide mixed light. Then, all other pixels are scanned in sequence till the grey level (R33, 0, 0) of the last pixel (3, 3), as shown in Figure 9B. The same process is applied to the green and blue grey levels of all pixels. When the grey level (0, 0, B33) of the last pixel (3, 3) is scanned, as shown in Figure 9C, all on/off states must be finished within time of vision persistence. Please notice that grey level in this embodiment is controlled by the LEDs only.

[0099] The operation of vision persistence to human eyes can be referred to Figure 10, wherein each pixel is turned on and off completely. In this embodiment, each pixel must be turned on and off three times due to there is no mixed color provided by the backlight module.

[00100] In this embodiment, both the color and the spatial sequences are immaterial; that means all green grey levels of all pixels can be processed first, then the blue grey levels, and the red grey levels last. The color sequence even can be interlaced. For example, the first pixel (1, 1) can be turned on first and the backlight module provides red grey level. Then, the fifth pixel (2, 2) can be turned on and the backlight module provides blue grey level. As long as all pixels with all colors are scanned once within time of vision persistence.

[00101] Another embodiment to display an image is the single-color image interlaced method. Similarly, all grey levels of each pixels are determined first. At first, the backlight module provides the full grey level red light, and at the same time, every pixel is turned on with corresponding grey level, as shown in Figure 11 A. Then, the backlight module provides full grey level green light, and at the same time, every pixel is turned on with corresponding grey levels, as shown in Figure 11B. Next, the backlight module provides full grey level blue light, and at the same time, every pixel is turned on with corresponding grey levels, as shown in Figure 11C. The operation of vision persistence to human eyes can be referred to Figure 12, wherein when the backlight provides red light with full grey level, each pixel will determine the grey level thereof, and so on to the green and blue lights. Hence, grey levels of each pixel are not the same within time of vision persistence, and are controlled the twisted angles of liquid crystal with respect to the corresponding image grey levels of the pixel. In this embodiment, single-color images are interlaced within time of vision persistence, and the color display sequence is not important also. In this embodiment, although grey levels of colors are determined by the pixels instead of backlight module, resolutions are the same as the previous two embodiments. Also notice that grey level in this embodiment is controlled by the TFTs and liquid crystal instead of LEDs.

[00102] The present invention thus provides a liquid crystal display panel without the use of a color filter, as shown in Figure 13. Each LED assembly 100-1 and 100-2 corresponds to two zones. Each LED assembly 100-1 and 100-2 includes at least a red, a green, and a blue LED chip. Two polarizers 16-1 and 16-2 individually cover areas of the LED assembly 100-1 and 100-2 respectively, which are provided zonewise or piecewise. The liquid crystal display panel includes a lower plate 14, an upper plate 10, and a liquid crystal layer between the plates, wherein TFTs configured in each pixel in the lower plate 14 can control on/off states of liquid crystal. Another polarizer 12 is attached to the upper plate 10. Images displayed on the LCD display panel can be divided into a plurality of zones and each zone can be displayed by the methods described above within time of vision persistence.

[00103] Another embodiment can be referred to Figure 14, wherein the LED assembly 100-3 and 100-4 provides COB (Chip On Board) configuration. All LED chips are bonding to board directly and transparent resin 110 encapsulate each zone. [00104] In the present invention, black level displayed by the LCD display panel is much better, because backlight module can be turned off completely while the backlight module of the conventional LCD display device is always on such that leakage of lights is inevitably. When viewing the images or films in a dark environment, the leakage lights become very obvious. Local dimming technology is introduced to improve this light leakage issue. In the conventional LCD device, a plurality of white LEDs is configured as a direct back light, for example 30,000 LEDs. Then, several LEDs are grouped into a zone, for example 12 LEDs grouped in a zone. When an image is displayed, the backlight of a specific zone may be tuned off if the image is black. In this invention, the multiple assemblies, such as RGB LED assemblies, can also be configured together as a zone, and local dimming technology can be applied. Dimming technology is inherent in this invention and can be called as nature dimming technology without further driving method.

[00105] In the present invention, backlight utilization is very high due to that there is no color filter. No matter what kinds of displaying methods are used, power consumption of the LCD display panel of the present invention is thus lower than the conventional way.

[00106] In the present invention, brightness can be tripled compared to the conventional LCD display panel if the same backlight brightness is used, because there is no color filter.

[00107] In the present invention, each pixel can provide the three primary colors from LEDs directly as a color pixel, no need to have three sub-pixels as those used in the conventional LCD display device. Thus, resolution in the present invention can be tripled also, and this invention provides a technology that one TFT directly control a color pixel.

[00108] In the present invention, for the mixed-color pixel scanning method or the single-color pixel scanning method, it is easy to drive liquid crystal in all pixels because there are only on/off states for each pixel. The cost for manufacturing the liquid crystal panel is lower since no complicated grey level control is needed.

[00109] In the present invention, the color saturation in the images is better than the conventional LCD display device, because all colors come from LEDs directly. For the conventional LCD display device, colors are determined by both backlight and color filter, and the color saturation would be poor. The most obvious example is the gold color which can only be barely shown in the conventional LCD display device with color filter.

[00110] Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A liquid crystal display device, comprising: a liquid crystal display panel including a lower plate with a plurality of thin film transistors(TFTs) thereon, an upper plate with a transparent electrode thereon, and a liquid crystal layer between the lower and upper plates, wherein an image displayed is divided into a plurality of zones on the liquid crystal display panel; and a backlight module for providing lights to the liquid crystal display panel, wherein at least one solid-state lighting assembly of the backlight module illuminates one zone of the plurality of zones and includes at least a red solid-state lighting chip, a green solid-state lighting chip and a blue solid-state lighting chip, wherein an image displayed by the liquid crystal display device is a zone image-display method.

2. The liquid crystal display device according to claim 1 , wherein the zone image-display method includes a mixed-color pixel scanning method, a single-color pixel scanning method, and a single-color image interlaced method such that every single pixel in the liquid crystal display device provides red, green, and blue lights.

3. The liquid crystal display device according to claim 2, wherein the mixed-color pixel scanning method includes steps of: determining red, green, and blue intensities of each pixel in the zone; and turning on said each pixel completely in sequence in the zone, while the solid-state lighting assembly in sequence emits the determined red, green, and blue intensities synchronously within time frame of vision persistence.

4. The liquid crystal display device according to claim 3, wherein the solid-state lighting assembly provides grey levels large than 8bits.

5. The liquid crystal display device according to claim 4, wherein the solid-state lighting assembly is driven by a PWM driving method.

6. The liquid crystal display device according to claim 2, wherein the single-color pixel scanning method includes steps of: determining red, green, and blue intensities of each pixel in the zone; and turning on said each pixel completely in red/green/blue sequence in pixel-scanning sequence while the solid-state lighting assembly in sequence emits the determined red, green, and blue intensities synchronously in said red/green/blue sequence in pixel-scanning sequence within time frame of persistence of vision.

7. The liquid crystal display device according to claim 2, wherein the single-color image interlace method includes steps of: determining red, green, and blue intensities of each pixel in the zone; turning on all pixel, according to the determined grey levels, by using the plurality of TFTs according to the red, green, and blue intensities in red/green/blue sequence while the solid-state lighting assembly emits at full intensity in said red/green/blue sequence synchronously within time frame of persistence of vision.

8. The liquid crystal display device according to claim 2, wherein a polarizer is fit to the zone adjacent to the lower plate.

9. The liquid crystal display device according to claim 8, wherein a transparent resin of the solid-state lighting assembly includes a roughness surface thereon.

10. The liquid crystal display device according to claim 9, wherein the red, green and blue solid-state lighting chips are miniLED chips.

11. The liquid crystal display device according to claim 10, wherein the red, green and blue solid-state lighting chips are flip chip bonded to the assembly.

12. The liquid crystal display device according to claim 11, wherein the solid-state lighting assembly includes diffusors in said transparent resin.

13. The liquid crystal display device according to claim 10, wherein the solid-state lighting assembly includes a white LED chip, a yellow LED chip, a turquoise LED chip, a magenta LED chip, or a cyan LED chip.

14. The liquid crystal display device according to claim 1, wherein the liquid crystal includes TN/STN/IPS/MVA.

15. A method for display an image, comprising: providing a liquid crystal display device which includes: a lower plate with a plurality of TFTs thereon, an upper plate with a transparent electrode thereon, and a liquid crystal between the lower and upper plates, wherein the image is divided into a plurality of zones; and a backlight module for providing lights to the liquid crystal display panel, wherein at least one solid-state lighting assembly of the backlight module illuminates one zone of the plurality of zones and includes at least a red solid-state lighting chip, a green solid-state lighting chip and a blue solid-state lighting chip; determining red, green, and blue intensities of each pixel in the zone; and turning on said each pixel completely in sequence in the zone while the solid-state lighting assembly in sequence emits the determined red, green, and blue intensities synchronously within time of vision persistence.

16. The method according to claim 15, wherein the solid-state lighting assembly provides grey levels large than 8bits.

17. The method according to claim 16, wherein the solid-state lighting assembly is driven by a PWM driving method.

18. The method according to claim 17, wherein the solid-state lighting assembly includes diffusors.

19. A method for display an image, comprising: providing a liquid crystal display device which includes: a lower plate with a plurality of TFTs thereon, an upper plate with a transparent electrode thereon, and a liquid crystal between the lower and upper plates, wherein the image is divided into a plurality of zones; and a backlight module for providing lights to the liquid crystal display panel, wherein at least one solid-state lighting assembly of the backlight module illuminates one zone of the plurality of zones and includes at least a red solid-state lighting chip, a green solid-state lighting chip and a blue solid-state lighting chip; determining red, green, and blue intensities of all pixels in the zone; turning on each pixel grey levels by using the plurality of TFTs according to the red, green, and blue intensities in red/green/blue sequence while the solid-state lighting assembly in sequence emits a complete intensity in said red/green/blue sequence synchronously within time frame of persistence of vision.

20. The method according to claim 19, wherein the solid-state lighting assembly includes diffusors.