KR100933111B1 - Dual mode display - Google Patents

Abstract

The dual mode liquid crystal display (LCD) may function as a dual mode of a monochrome reflection mode and a color transmission mode. The present invention includes a color filter only on the transmissive portion of the pixel to make it possible to read ambient light. Another aspect of the invention is to remove the black matrix mask that was typically used in the generation of color filters. In addition, the present invention improves the resolution of the liquid crystal display in the color transmissive mode by arranging the pixels diagonally. In addition, when using a hybrid field sequential approach, aspects of the present invention allow the light to switch between two different colors while the third color (typically green) is always ON, thereby reducing the frame rate required by the liquid crystal display. Decrease. Another aspect of the invention is to remove color filters by generating color from the backlight. Another aspect of the present invention obviates the need for the use of additional masks to create color filter arrangements using color filters only over green filters.

Description

 Dual Mode Display {DUAL MODE DISPLAY}

The present invention relates generally to displays. More specifically, the present invention relates to a dual mode liquid crystal display (LCD).

Increasing the use of displays in various electrical elements puts pressure on display manufacturers to fabricate elements with better performance. The performance includes power consumption, resolution, frame refresh rate, price, and solar readability. Display manufacturers use a variety of techniques to improve performance based on these factors.

One such technique is used in the transflective liquid crystal display device. Each pixel of the transflective liquid crystal display has a reflecting portion and a transmitting portion. In addition, the transmission portion and the reflection portion include sub-pixels. Each subpixel has a color filter that gives the pixel a color. In addition, each sub-pixel is arranged horizontally or vertically. Three or more subpixels are required to display colors in the liquid crystal display.

In the above-mentioned approach, the color filter lies on the transmissive part and the reflecting part. Therefore, the light passing through the color filter is weakened, making the reflection mode faint and difficult to read. In addition, in the transmissive mode, the backlight requires a lot of power to obtain a high resolution display. In addition, the use of vertically or horizontally arranged subpixels provides low resolution. In addition, changing all color elements in the liquid crystal display requires high frequency and high power consumption.

In view of the above-mentioned problem, there is a need for a technique of making high resolution in a solar-readable liquid crystal display device. In addition, there is a need to develop a liquid crystal display device that requires low power and low frame rate. The present invention satisfies these needs.

It is an object of the present invention to provide a liquid crystal display device having a better resolution as compared with a conventional liquid crystal display device.

Another object of the present invention is to reduce the power required to illuminate a liquid crystal display.

Another object of the present invention is to reduce the frame rate in a liquid crystal display.

Another object of the present invention is to make a display capable of reading sunlight in a liquid crystal display.

The present invention provides a liquid crystal display device in which a color filter is placed only on the transmissive portion of a pixel so that ambient light can be read. Another aspect of the present invention is to remove the black matrix mask typically used in color filter fabrication. In addition, the present invention provides pixels in the diagonal direction to increase the resolution of the liquid crystal display in the color transmissive mode. In addition, aspects of the present invention switch the light between the other two colors while the third color (usually green) remains on, thereby reducing the required frame rate of the liquid crystal display when used in a hybrid field sequential approach. Another object of the present invention is to form color from the backlight, thereby removing the color filter. Another object of the present invention is to place the color filter only on the green pixels, thereby eliminating the need for additional masks to make the color filter arrangement.

DETAILED DESCRIPTION Various embodiments of the present invention will be described in conjunction with the accompanying drawings, and the embodiments will be described, but not limited to the present invention, like names refer to like elements.

1 is a schematic diagram showing a cross section of a pixel of a liquid crystal display according to an embodiment of the present invention.

2 shows an arrangement of nine pixels of the liquid crystal display according to the embodiment of the present invention.

3 shows the function of the liquid crystal display in the monochrome reflection mode according to the embodiment of the present invention.

4 illustrates the function of a liquid crystal display in color transmissive mode by using a partial color filter approach, according to an embodiment of the invention.

5 illustrates the function of a liquid crystal display in color transmissive mode by using a hybrid field sequential approach, in accordance with an embodiment of the invention.

6 illustrates the function of a liquid crystal display in color transmission mode by using a diffraction approach, according to an embodiment of the present invention.

Various embodiments of the present invention relate to a liquid crystal display (LCD) capable of functioning as a dual mode, a monochromatic reflective mode, and a color transmissive mode. Various modifications, general principles, and features to the preferred embodiments described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and features described herein.

1 is a schematic diagram showing a cross section of a pixel 100 of a liquid crystal display according to an embodiment of the present invention. The pixel 100 includes a liquid crystal crystal material 104, a pixel electrode 106, a common electrode 108, a reflector 110, a transmissive portion 112, a substrate 114 and 116, a spacer 118a and 118b, and a first polarizer. 120, and a second polarizer 122. In an embodiment of the invention, the light source 102 or ambient light 124 illuminates the pixel 100. Examples of the light source 102 include, but are not limited to, light emitting diodes (LEDs), cold cathode fluorescent lamps (CCFLs), and the like. The ambient light 124 may be sunlight or any external light source. In an embodiment of the invention, an optically active material, liquid crystal crystalline material 104, rotates the polarization axis of light exiting from the light source 102 or ambient light 124. The liquid crystal crystal 104 may be twisted nematics (TN), electrically controlled birefringence (ECB), or the like. In an embodiment of the invention, the rotation of the light plane is determined by the potential difference applied between the pixel electrode 106 and the common electrode 108. In an embodiment of the present invention, pixel electrode 106 and common electrode 108 may be made of phosphorus-tin oxide (ITO). In addition, the common electrode 108 is commonly connected to all the pixels present in the liquid crystal display, while the pixel electrode is provided to each pixel.

In one embodiment of the present invention, the reflector 110 is electrically conductive in order to illuminate the pixel 100 and reflects the ambient light 124. The reflector 110 is made of metal and electrically coupled with the pixel electrode 106, thereby generating a potential difference between the reflector 110 and the common electrode 108. The transmission part 112 transmits light emitted from the light source 102 to illuminate the pixel 100. Substrates 114 and 116 surround liquid crystal crystal material 104, pixel electrode 106 and common electrode 108. In an embodiment of the present invention, pixel electrode 106 is located on substrate 114 and common electrode 108 is located on substrate 116. In addition, the substrate 114 includes a switching element (not shown in FIG. 1). In an embodiment of the invention the switching elements may be thin film transistors (TFTs). In addition, the drive circuit 130 sends a signal related to the pixel value to the switching element. In an embodiment of the invention, the drive circuit 130 uses a low voltage differential signaling (LVDS) driver. In another embodiment of the invention, the drive circuit 130 uses a transistor-transistor logic (TTL) interface that senses the increase and decrease of the voltage. In addition, the timing controller encodes the signal related to the pixel value into a signal required by the transmissive part of the pixel in the diagonal direction. In addition, the timing controller has a memory that enables self-regeneration of the liquid crystal display when the signal related to the pixel is removed from the timing controller.

In an embodiment of the present invention, spacers 118a and 118b are positioned over the reflector 110 to maintain a constant distance between the two substrates 114 and 116. In addition, the pixel 100 includes a first polarizer 120 and a second polarizer 122. In an embodiment of the present invention, the polarization axis of the first polarizer 120 and the polarization axis of the second polarizer 122 are perpendicular to each other. In another embodiment of the present invention, the polarization axis of the first polarizer 120 and the polarization axis of the second polarizer 122 are parallel to each other.

Pixel 100 is illuminated by light source 102 or ambient light 124. The intensity of light passing through the pixel 100 is determined by the potential difference between the pixel electrode 106 and the common electrode 108. In an embodiment of the present invention, when no potential difference is formed between the pixel electrode 106 and the common electrode 108, the liquid crystal crystal material 104 is in an disordered state and the light passing through the first polarizer 120 is second. Blocked by polarizer 122. When a potential difference is formed between the pixel electrode 106 and the common electrode 108, the liquid crystal crystal material 104 becomes directional. Directivity of the liquid crystal crystalline material 104 allows light to pass through the second polarizer 122.

2 illustrates an arrangement of nine pixels 100 of a liquid crystal display according to an embodiment of the present invention. The pixel 100 includes a transmission part 112b and a reflection part 110. In an embodiment of the present invention, if the RBG color system is allowed, the transmissive portions 112a-c emit green, blue and red elements, respectively, to form color pixels. Additionally, if different color systems are selected, the transmissive portions 112a-c may produce different colors, such as red, green, blue, and white or other color combinations. In addition, the transmissive portions 113a and 114a have a green color, the transmissive portions 113b and 114b have a blue color, and the transmissive portions 113c and 114c have a red color. In addition, color filters having different thicknesses are positioned above the transmissive portions 112a-c, thereby reducing or increasing the saturation of the color emitted to the color pixels. Saturation is defined as the degree of fading of a particular color in the visible spectrum. In addition, a colorless filter 202d may be placed on the reflector 110. In an embodiment of the present invention, the thickness of the colorless filter 202d may vary from zero to the thickness of another color filter placed on the transmissive portions 112a-c. In the embodiment of the present invention, the transmissive portion 112a means a diagonal stripe of one of the three colors of the color pixel. Similarly, the transmissive portions 112b and 112c mean diagonal stripes of the other two colors of the color pixel. Diagonal stripes are used so that the resolution of the color in the transmission mode is close to the resolution in the monochrome (black and white) reflection mode. Since the human visual system can detect horizontal and vertical lines while viewing the image, the resolution in transmission mode is higher. In another embodiment of the present invention, the use of vertical stripes of color results in a greater change in resolution in the horizontal direction and a smaller change in resolution in the vertical direction when compared with the use of diagonal stripes. The amount of light passing from each light source 102 through each transmission 112a-c is determined by a switching element (not shown in FIG. 2). In turn, the amount of light passing through each transmission portion 112a-c determines the color of the color pixel. In addition, the shapes of the transmissive portions 112a-c and the color filters may be hexagonal, rectangular, octagonal, circular, or the like. Additionally, the shape of the reflector 110 may be rectangular, circular, octagonal, or the like. In addition, the reflector 110 prevents the light transmitted to the stripes of the diagonal direction from being transmitted to the pixels of different colors. For example, the reflector 110 transmits the light along the transmission parts 112c and 113c. Do not enter 112a). Alternatively, a black matrix mask 203 covering the pixel and light sensing portion can be used. In an embodiment of the invention, the black matrix mask 203 is removed to improve the reflectivity of the pixel.

Figure 3 illustrates the functionality of pixel 100 in monochromatic reflection mode, in accordance with an embodiment of the invention. Since the monochromatic reflective embodiment is described in FIG. 3, only the reflector 110 is shown in the figure. In the monochrome reflection mode, the pixel 100 may be used in front of an external light source. In an embodiment of the present invention, the ambient light 124 passes through the colorless filter 202d and the liquid crystal material 104 and enters the reflector 110. The colorless filter 202d is used to maintain the path difference of the ambient light 124 to the same degree of attenuation, attenuation, and light path difference in the color transmission mode. The reflector 110 of the pixel 100 reflects the ambient light 124 to the substrate 116. In an embodiment of the present invention, a potential difference v is formed between the pixel electrode 106 and the common electrode 108 electrically coupled with the reflector 110. The liquid crystal material 104 is directional depending on the potential difference v. As a result, the directionality of the liquid crystal material 104 rotates the plane of the ambient light 124, which allows the light to pass through the second polarizer 122. Therefore, the degree of directivity of the liquid crystal material 104 determines the brightness of the pixel 100 and consequently the brightness of the pixel 100.

In an embodiment of the present invention, a normal white liquid crystal embodiment may be used for the pixel 100. In this embodiment of the present invention, the axis of the first polarizer 120 and the axis of the second polarizer 122 are parallel to each other. A maximum threshold voltage is formed between the pixel electrode 106 and the common electrode 108 to block the light reflected by the reflector 110. Thus, pixel 100 looks black. Alternatively, ordinary black liquid crystal embodiments can be used. In this embodiment of the present invention, the axis of the first polarizer 120 and the axis of the second polarizer 122 are perpendicular to each other. A maximum threshold voltage is formed between the pixel electrode 106 and the common electrode 108 to illuminate the pixel 100.

4 illustrates the function of a liquid crystal display in color transmissive mode by using a partial color filter approach, according to an embodiment of the invention. Since the color transmissive embodiment has been described, only transmissive portions 112a-c are shown in FIG. 4. As shown in FIG. 4, color filters 404a, 404b, 404c are positioned for the transmissive parts 112a, 112b, 112c, respectively, on the substrate 116. FIG. The light source 102 is a standard backlight source. The light 402 emitted from the light source 102 may be paralleled using a light collimator or a light collimation lens. In an embodiment of the invention, the light 402 emitted from the light source 102 passes through the first polarizer 120. This aligns the light 402 in a particular plane. In an embodiment of the invention, the planes of light 402 are aligned in the horizontal direction. In addition, the second polarizer 122 has a polarization axis in the vertical direction. Transmitting portions 112a-c pass light 402. In an embodiment of the invention, each transmissive portion 112a-c has a separate switching element. The switching element controls the intensity of the light passing through the corresponding transmission. In addition, light 402 that has passed through transmissions 112a-c then passes through liquid crystal material 104. Transmitting portions 112a, 112b and 112c are provided to the pixel electrodes 106a-c, respectively. The potential difference between the pixel electrodes 106a-c and the common electrode 108 determines the directivity of the liquid crystal material 104. In turn, the directionality of the liquid crystal material 104 determines the intensity of light 402 incident on each color filter 404a-c.

In an embodiment of the invention, the green color filter 404a is positioned above the transmissive portion 112a, the blue color filter 404b is positioned above the transmissive portion 112b, and the red color filter 404c is positioned above the transmissive portion 404c. Each filter 404a-c produces a color corresponding to a color pixel. The color produced by the color filters 404a-c determines the color difference value of the color pixel. The color difference includes color information such as hue and resolution in the pixel. In addition, if there is ambient light 124, the light reflected by reflector 110 (shown in FIGS. 2 and 3) provides luminance to the color pixels. Therefore, this brightness increases the resolution in color transmission mode. Luminance is the degree of pixel brightness.

5 illustrates the function of a liquid crystal display in color transmissive mode by using a hybrid field sequential approach, in accordance with an embodiment of the invention. Since the color transmissive embodiment has been described, only transmissive portions 112a-c are shown in FIG. 5. In an embodiment of the invention, the light source 102 comprises an array of LEDs such as a first LED group, a second LED group. In an embodiment of the invention, the LEDs arranged horizontally are grouped together, and one LED group is located below the other group to illuminate the liquid crystal display. Alternatively, vertically arranged LEDs can be grouped. LEDs groups are illuminated in a sequential manner. The number of lights in the LED group can be between 30 and 540 frames per second. In an embodiment of the invention, each LED group includes red LEDs 506a, white LEDs 506b, and blue LEDs 506c. In addition, the red LEDs 506a and the white LEDs 506b of the first LED group are ON between the times t = 0 and t = 5, and the red LEDs 506a and the white LEDs 506b of the second LED group are ON time t = 1 to t = 6. Similarly, the red and white LEDs of other LED groups function in a sequential manner. In the embodiment of the present invention, in the case where the LED groups are arranged vertically, each LED group illuminates horizontal rows of pixels of the liquid crystal display. Similarly, the blue LEDs 506c and white LEDs 506b of the first LED group are ON between time t = 5 and t = 10, and the blue LEDs 506c and white LEDs 506b of the second LED group. Is ON between time t = 6 and t = 11. Similarly, blue and white LEDs of other LED groups are turned on in a sequential manner. Red LEDs 506a, white LEDs 506b, and blue LEDs so that the red LEDs 506a and blue LEDs 506b illuminate the transmissive portions 112a, 112c and the white LEDs 506b illuminate the transmissive portions 112b. 506b is arranged. In another embodiment of the present invention, the LED group may include red, green and blue LEDs. Red, green and blue LEDs are arranged so that green LEDs illuminate transmissive portion 112b and red and blue LEDs illuminate transmissive portions 112a and 112c, respectively.

In an embodiment of the invention, the light 502 emitted from the light source 102 passes through the first polarizer 120. First polarizer 120 aligns the plane of light 502 in a particular plane. In an embodiment of the invention, the planes of light 502 are aligned in a horizontal direction. In addition, the second polarizer 122 has a polarization axis in the vertical direction. Transmitting portions 112a-c pass light 502. In an embodiment of the invention, each transmissive portion 112a-c has a separate switching element. In addition, the switching element controls the intensity of light passing through each transmission portion 112a-c, thereby controlling the intensity of the color element. In addition, light 502 passes through liquid crystal material 104 after passing through transmissions 112a-c. Each transmissive portion 112a-c has a separate pixel electrode 106a-c. The potential difference between the pixel electrodes 106a-c and the common electrode 108 determines the directivity of the liquid crystal material 104. In embodiments in which red, white, and blue LEDs are used, the intensity of the light 502 incident on the green color filter 504 and the transparent spacers 508a and 508b is sequentially directed to the liquid crystal material 104. Determine. The intensity of light 502 passing through the green filter 504 and the transparent spacers 508a and 508b determines the color difference value of the color pixel. In an embodiment of the invention, the green color filter 504 is positioned corresponding to the transmissive portion 112b. The transmissive parts 112a and 112c do not have a color filter. Alternatively, the transmissive portions 112a and 112c may use transparent spacers 508a and 508b, respectively. Green filter 504 and transparent spacers 508a and 508b are positioned over substrate 116. In another embodiment of the present invention, a magenta color filter may be positioned over the transparent spacers 508a and 508b. In an embodiment of the invention, during the time t = 0 to t = 5, when the red LEDs 506a and the white LEDs 506b are turned ON, the permeables 112a and 112c are red and green filters 504. ) Gives a green color to the transmissive portion 112b. Similarly, during the time t = 6 to t = 11, when the blue LEDs 506c and the white LEDs 506b are turned ON, the transmission parts 112a and 112c are blue and the green filter 504 is the transmission part ( 112b) gives a green color. The color given to the color filter is formed by the combination of colors in the transmissive portions 112a-c. In addition, if ambient light 124 is available, the light reflected by the reflector 110 shown in FIGS. 2 and 3 illuminates the color pixels. Therefore, such illumination increases the resolution in color transmission mode.

6 illustrates the function of a liquid crystal display in color transmission mode by using a diffraction approach, according to an embodiment of the present invention. Since the color transmissive embodiment has been described, only transmissive portions 112a-c are shown in FIG. 6. The light source 102 can be a standard backlight source. In an embodiment of the invention, the light 602 emitted from the light source 102 is divided into a green element 602a, a blue element 602b and a red element 602c using the diffraction grating 604. Alternatively, light 602 is divided into a spectrum of colors with different portions of the spectrum passing through each transmission 112a-c, using a micro-optical instrument. In an embodiment of the present invention, the micro-optical device is a flat film optical device with a small lens imprinted or attached to the film. The green element 602a, the blue element 602b and the red element 602c are directed to the transmission portions 112a, 112b and 112c using the diffraction grating 604, respectively. In addition, elements of light 602 pass through first polarizer 120. This aligns the plane of the light elements 602a-c in a particular plane. In an embodiment of the invention, the planes of the light elements 602a-c are aligned in the horizontal direction. Additionally, the second polarizer 122 has a polarization axis in the horizontal direction. Transmissive portions 112a-c allow optical elements 602a-c to pass through transmissive portions 112a-c. In an embodiment of the invention, each transmission 112a-c has a separate switching element. The switching element controls the intensity of the light passing through the transmissions 112a-c, thereby controlling the intensity of the color element. In addition, the light elements 602a-c pass through the liquid crystal material 104 after passing through the transmissive portions 112a-c. The transmissive parts 112a, 112b and 112c have pixel electrodes 106a, 106b and 106c, respectively. The potential difference between the pixel electrodes 106a-c and the common electrode 108 determines the directivity of the liquid crystal material 104. In turn, the directivity of the liquid crystal material 104 determines the intensity of the light elements 602a-c that have passed through the second polarizer 122. In turn, the intensity of the light element passing through the second polarizer 122 determines the color difference of the color pixel. In addition, if ambient light is useful, the light reflected by the reflector 110 (shown in Figures 2 and 3) illuminates the color pixels. Therefore, such illumination increases the resolution in color transmission mode.

In the present specification, as in the case of the liquid crystal display device known in the art, the transmissive portions of the pixels are arranged in a diagonal direction, not vertically or horizontally. Compared with the conventionally known liquid crystal display device, arranging the transmissive portions diagonally increases the resolution and provides a better display.

In addition, the presence of ambient light enhances the illumination of the color pixels in the color transmission mode. Therefore, each pixel has both luminance and color difference. This increases the resolution in the liquid crystal display device. As a result, the number of pixels required for a particular resolution is smaller than that of a conventional liquid crystal display, thereby reducing the power consumption of the liquid crystal display. In addition, the use of an interface based on transistor-transistor logic (TTL) enables a smaller amount of power consumption compared to the power consumption by interfaces used in conventionally known liquid crystal displays. In addition, since the timing controller stores a signal related to the pixel value, the liquid crystal display utilizes the self-renewing property to the maximum, thereby reducing power consumption. In various embodiments of the invention, thinner color filters may be used that allow saturated colors and more light to pass through. Therefore, various embodiments of the present invention utilize a process for reducing power consumption as compared to conventionally known liquid crystal displays.

In addition, in the embodiment of the present invention (described in FIG. 5), green or white colored light is always visible in the pixel 100 and only red and blue colored light are switched. Therefore, when compared to the frame rate of the conventionally known area sequential display, it has a lower frame rate.

While preferred embodiments of the invention have been described and described, it will be clear that the invention is not limited to these embodiments. Numerous variations, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as set forth in the claims.

Claims (14)

A light source illuminating the dual mode display; A first polarizer for aligning a plane of polarization of the light emitted from the light source to a first plane; A second polarizer for aligning a plane of polarization of the light emitted from the light source to a second predefined plane; A first substrate and a second substrate positioned between the first polarizer and the second polarizer; And A plurality of pixels, each positioned on the first substrate, each including a reflecting portion and a transmitting portion, wherein the reflecting portion does not include a color filter and at least a portion of the transmitting portion includes one or more color filters Dual mode liquid crystal display comprising a. The method of claim 1, And the reflector occupies opposite edges of the plurality of pixels. The method of claim 1, And the transmissive portion occupies the center portion of the plurality of pixels. The method of claim 1, The color mode is generated from the light emitted from the light source by using a diffraction film or a micro-optical film. The method of claim 1, And the transmissive part is arranged in a diagonal direction. The method of claim 1, And the at least one color filter has a different thickness. The method of claim 1, And the at least one color filter has the same thickness as each other. The method of claim 1, And at least one colorless spacer disposed on the reflector. The method of claim 8, And the at least one colorless spacer has the same thickness as each other. The method of claim 8, And at least one colorless spacer has a different thickness. The method of claim 1, And a driving circuit for providing pixel values to the plurality of switching elements for determining light passing through the transmission part. The method of claim 11, A dual mode liquid crystal display further comprising a transistor-transistor logic interface. The method of claim 11, And a time adjustment control circuit for reproducing pixel values of the dual mode liquid crystal display. The method of claim 1, And the dual mode liquid crystal display is used in a notebook computer.

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