Transflective display device

A transflective display device of the present invention includes a backlight module, an electrophoretic device, and a liquid crystal panel. The electrophoretic device includes a first substrate; a second substrate; an electrophoretic layer; a collector; a gate electrode and a plurality of transparent electrodes. The first substrate has at least a pixel region, and a device region and a display region are defined in the pixel region. The first substrate is disposed oppositely to the second substrate, and the electrophoretic layer is disposed between the first substrate and the second substrate. The electrophoretic layer includes a transparent fluid and a plurality of opaque charged particles. The collector, the gate electrode, and the plurality of transparent electrodes are disposed between the first substrate and the second substrate, wherein the collector and the gate electrode are disposed in the device region and the transparent electrodes are disposed in the display region.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a transflective display device, and more particularly, to the transflective display device in which the same pixel region is capable of being operated in any one of the modes including a transmission mode, a reflection mode and a transflective mode.

2. Description of the Prior Art

Based on the differences of the light source and the array substrate, the liquid crystal displays (LCDs) may be classified into three types including transmissive LCDs, reflective LCDs, and transflective LCDs. With the popularization of LCDs and portable electronic products, the display quality of LCD in the bright outdoor environment, in the indoor environment, and even in the dark must be all considered. In all of the above conditions, the transflective LCD is a better choice for it can provide the same high contrast image.

The ratio of transmission region to reflective region in each pixel region of the conventional transflective LCD, however, is designed to be constant, which means, the ratio of transmission region to reflective region cannot be adjusted when the viewing environment changes. This restriction makes the conventional transflective LCD unable to select the most adequate display mode from the transmission mode, the reflection mode and the transflective mode, and thus the optimal display quality cannot be obtained.

SUMMARY OF THE INVENTION

It is therefore one of the objectives of the present invention to provide a transflective display device to solve the problems in the conventional display device.

An exemplary embodiment of the transflective display device of the present invention includes a backlight module, an electrophoretic device, and a liquid crystal panel. The backlight module is for emitting a backlight and the electrophoretic device is disposed on the backlight module. Moreover, the electrophoretic device includes a first substrate, a second substrate, an electrophoretic layer, a collector, a gate electrode and a plurality of transparent electrodes. The first substrate has at least a pixel region, and a device region and a display region are defined in the pixel region. The first substrate is disposed oppositely to the second substrate. The electrophoretic layer disposed between the first substrate and the second substrate includes a transparent fluid and a plurality of opaque charged particles. The collector, the gate electrode, and the plurality of transparent electrodes are disposed between the first substrate and the second substrate, wherein the collector and the gate electrode are disposed in the device region, and the plurality of transparent electrodes are disposed in the display region. Further, the liquid crystal panel is disposed on the electrophoretic device.

The transflective display device of the present invention utilizes the collector, the gate electrode, and the plurality of transparent electrodes disposed in the electrophoretic device to change the distribution of the opaque charged particles based on different environmental condition. Accordingly, the pixel regions of the transflective display device are able to be operated in any one of display modes including transmission mode, reflection mode and transflective mode for providing better display quality.

DETAILED DESCRIPTION

Certain terms are used throughout the following descriptions and claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but in function. In the following discussion and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Furthermore, the diagrams are meant to explain the invention, but not based on the original scale.

Please refer toFIG. 1.FIG. 1illustrates a schematic diagram of a transflective display device according to a first exemplary embodiment of the present invention. As shown inFIG. 1, the transflective display device100comprises a backlight module10, an electrophoretic device20, and a liquid crystal panel30. The backlight module10is disposed for emitting a backlight, and the electrophoretic device20is disposed on the backlight module10. Moreover, the electrophoretic device20comprises a first substrate21; a second substrate22; an electrophoretic layer23; a collector24; a gate electrode25and a plurality of transparent electrodes26. The first substrate21comprises at least a pixel region P having a device region C and a display region D defined thereon. For simplification, the following description is focused on one pixel region P, but not limited thereto. In other words, the first substrate21may have a plurality of pixel regions P. The second substrate22is disposed oppositely to the first substrate21. The electrophoretic layer23is disposed between the first substrate21and the second substrate22, and comprises a transparent fluid231and a plurality of opaque charged particles232. The charges of the opaque charged particles232can be positive, but not limited thereto. For instance, the charges of the opaque charged particles232can also be negative. The collector24, the gate electrode25and the plurality of transparent electrodes26are disposed between the first substrate21and the second substrate22. The collector24and the gate electrode25are disposed in the device region C, and may be made of opaque conductive material such as metal or transparent conductive material such as Indium Tin Oxide (ITO), while the plurality of transparent electrodes26disposed in the display region D are made of transparent conductive material. In the first exemplary embodiment of the present invention, the collector24, the gate electrode25and the plurality of transparent electrodes26are disposed on the surface of the first substrate21facing the second substrate22, but not limited thereto. That is, in another exemplary embodiment of the present invention, the collector24may be disposed on a surface of the second substrate22facing the first substrate21, while the gate electrode25and the plurality of transparent electrodes26may be disposed on a surface of the first substrate21facing the second substrate22. In other words, the collector24, the gate electrode25and the plurality of transparent electrodes26are required to be disposed between the first substrate21and the second substrate22, but are free to be disposed on either the first substrate21or the second substrate22. Furthermore, the collector24, the gate electrode25and the plurality of transparent electrodes26are not confined to be disposed on the same substrate.

As shown inFIG. 1, the liquid crystal panel30is disposed on the electrophoretic device20. The liquid crystal panel30comprises an array substrate31, a third substrate32, a liquid crystal layer33and a color filter34. In the first exemplary embodiment of the present invention, the second substrate22of the electrophoretic device20is the same substrate as the array substrate31of the liquid crystal panel30, but not limited thereto. The array substrate31is disposed oppositely to the third substrate32, the liquid crystal layer33is disposed between the third substrate32and the array substrate31, and the color filter34is disposed on the third substrate32. In a transflective mode, compared to the backlight emitted from the backlight module10, a reflected light passing through the liquid crystal panel30twice suffers a great loss when passing the color filter34, therefore the color filter34may comprise at least an over coat341, which is transparent, for reducing loss of the reflected light. Moreover, a light-shielding layer342may be disposed on the third substrate32and substantially corresponds to the device region C of the first substrate21for increasing the contrast. In addition, as illustrated inFIG. 1, a pixel electrode35is disposed on the array substrate31, and a common electrode36is disposed on the third substrate32. The voltage difference provided by the pixel electrode35and the common electrode36controls a plurality of liquid crystals of the liquid crystal layer33for providing display images.

Furthermore, the transflective display device100also comprises a first polarizer41, a second polarizer42, a first wave plate43, and a second wave plate44. In the first exemplary embodiment of the present invention, the first polarizer41and the first wave plate43are disposed on the surface of the first substrate21facing the backlight module10, while the second polarizer42and the second wave plate44are disposed on the surface of the third substrate32. It is appreciated that the liquid crystal layer33of the first exemplary embodiment is a mixed-mode twisted nematic (MTN) liquid crystal layer. To comply with the MTN liquid crystal layer, in the first exemplary embodiment of the present invention, the first polarizer41and the second polarizer42possess the same polarization direction; further, the first wave plate43and the second wave plate44are both ¼ wave plates. That is, the phase difference of a light after passing through the first polarizer41and the second polarizer42is substantially ¼ wavelength. Compared to the normal twisted nematic liquid crystal layer, the MTN liquid crystal layer provides higher brightness and prevents the parallax issue that the conventional reflective LCD possessed. However, the liquid crystal type of the liquid crystal layer33is not limited to MTN, and other types of liquid crystal layer may be utilized as well. For instance, in another exemplary embodiment, the liquid crystal layer33inFIG. 1could be a vertical alignment (VA) type liquid crystal layer. To comply with the VA liquid crystal layer, the first polarizer41and the second polarizer42are perpendicular or parallel to each other on the basis of the designed phase difference, and the angle of disposing the first polarizer41and the second polarizer42is unspecified. Also, the angle of disposing the first wave plate43and the second wave plate44can be determined by the calculation of polarization.

To make one skilled in the art understand the present invention more, other exemplary embodiments of the present invention are discussed in the following paragraphs. With the schematic diagrams illustrating the transflective display device100of the first exemplary embodiment of the present invention operated in a transmission mode/a reflection mode/a transflective mode; and the operation voltages of the collector24, the gate electrode25and the transparent electrodes26in the three modes, the structure and the effect of the present invention are explained in details. It is to be noted that the operation voltage varies with different transparent fluid231and opaque charged particles232used in the present invention, and thus the operation voltage in the following description is only for explanation, but not limited thereto. Additionally, to simplify the explanation,FIG. 2,FIG. 4,FIG. 6, andFIG. 8only illustrate the first substrate21, the collector24, the gate electrode25and four of the transparent electrodes26of the transflective display device100shown inFIG. 1, and the charge of the opaque charged particles232is positive in the following description, but not limited thereto. The charge of opaque charged particles232can also be negative, which can be driven by different electric field.

Please refer toFIG. 2-FIG.3.FIG. 2-FIG.3illustrate schematic diagrams of the transflective display device100according to the first exemplary embodiment of the present invention in the transmission mode. As shown inFIG. 2, the initial voltage of the collector24, the gate electrode25and the transparent electrodes26are zero, and in the meantime, the opaque charged particles232are distributed randomly on the first substrate21. Then, the settings of voltage are adjusted as follows: the voltage of the collector24is kept zero, the gate electrode25is supplied with a voltage of 6V, the transparent electrode26most adjacent to the gate electrode25is supplied with a voltage of 9V, and the transparent electrode26most away from the gate electrode25is supplied with a voltage of 15V. Accordingly, in the present invention, the opaque charged particles232are driven to be gathered on the collector24by the electric field generated by the voltage difference between the transparent electrode26most away from the gate electrode25and the gate electrode25, and by the electric field generated by the voltage difference between the gate electrode25and the collector24as well. The way to drive the opaque charged particles232is not limited thereto, in another exemplary embodiment, the opaque charged particles232can also be driven to be gathered on the collector24only by the electric field generated by the voltage difference between the transparent electrode26most away from the gate electrode25and the collector24. Subsequently, the settings of voltage are adjusted as follows: the gate electrode25is supplied with a voltage of 9V, and the voltage of the collector24and all of the transparent electrodes26are zero. As a result, the opaque charged particles232are gathered on the collector24. Accordingly, as shown inFIG. 3, in the transmission mode, the opaque charged particles232are gathered on the collector24, and the backlight L1are able to pass through the transparent electrodes26to reach the liquid crystal panel30. In other words, the backlight L1emitted from the backlight module10passes through the electrophoretic device20, such that the display region D is a transmission region.

Please refer toFIG. 4-FIG.5.FIG. 4-FIG.5illustrate schematic diagrams of the transflective display device100of the first exemplary embodiment of the present invention in the reflection mode.FIG. 4illustrates the transflective display device100of the first exemplary embodiment when switching to the reflection mode. It is appreciated that before switching to the reflection mode, a reset procedure substantially identical to the steps shown inFIG. 2is suggested. The reset procedure gathers the opaque charged particles232on the collector24for in advance to proceed the following progress. As illustrated inFIG. 4, the initial voltage of the collector24and the transparent electrodes26are zero, while the initial voltage of the gate electrode25is 9V, such that the opaque charged particles232are gathered on the collector24. Then, the settings of voltage are adjusted as follows: the voltage of the collector24and the gate electrode25are zero, while the four transparent electrodes26are supplied with voltages of −6V, −9V, −12V, −15V, respectively, based on the distance of the transparent electrode26from the gate electrode25. That is, the voltage of the transparent electrode26adjacent to the gate electrode25is set higher than the voltage of the transparent electrode26away from the gate electrode25Accordingly, in the present invention, the opaque charged particles232are driven to cover the transparent electrodes26from the collector24by the electric field generated by the voltage difference between the transparent electrodes26and the collector24. Additionally, the opaque charged particles232can be dispersed uniformly on the four transparent electrodes26by the electric field generated by the voltage difference between the two neighboring transparent electrodes26. Subsequently, the settings of voltage are adjusted as follows: the voltage of the gate electrode25is 9V, and the voltage of the collector24and all of the transparent electrodes26are adjusted to zero. Consequently, the opaque charged particles232can be maintained on the transparent electrodes26. Accordingly, as shown inFIG. 5, in the reflection mode, the transparent electrodes26are covered with the opaque charged particles232for reflecting the ambient light L2. In other words, the display region D is a reflective region in this exemplary embodiment.

Please refer toFIG. 6-FIG.7.FIG. 6-FIG.7illustrate schematic diagrams of the transflective display device100of the first exemplary embodiment of the present invention in the transflective mode.FIG. 6illustrates the transflective display device100of the first exemplary embodiment when switching from the transmission mode to the transflective mode. As shown inFIG. 6, the initial voltage of the collector24and the transparent electrodes26are zero, while the initial voltage of the gate electrode25is 9V, such that the opaque charged particles232are gathered on the collector24. Then, the settings of voltage are adjusted as follows: the voltage of the collector24and the gate electrode25are zero, while the four transparent electrodes26are supplied with voltages of −6V, −15V, −6V, −6V, respectively. That is, the voltage of one of the transparent electrodes26is lower than the voltage of the other transparent electrodes26. Accordingly, in the present invention, the opaque charged particles232are driven to cover the transparent electrodes26from the collector24by the electric field generated by the voltage difference between the transparent electrodes26and the collector24. Additionally, a portion of the transparent electrodes26(such as the two transparent electrodes26adjacent to the gate electrode25inFIG. 6) are covered with the opaque charged particles232by the electric field generated by the voltage difference between the transparent electrode26with lower voltage and the other transparent electrodes26with higher voltage. Subsequently, in order to keep the distribution of the opaque charged particles232, the settings of voltage are adjusted as follows: the voltage of the collector24and two of the transparent electrodes26adjacent to the gate electrode25are adjusted to be zero, while the gate electrode25and the other transparent electrodes26are supplied with a voltage of 9V. Accordingly, as shown inFIG. 7, in the transflective mode, a portion of the transparent electrodes26is covered with a plurality of the opaque charged particles232for reflecting the ambient light L2, and the backlight L1passes through the transparent electrodes26uncovered by the opaque charged particles232to reach the liquid crystal panel30. In other words, the display region D has both of a reflective region and a transmission region in this exemplary embodiment.

Please refer toFIG. 8-FIG.9.FIG. 8-FIG.9illustrate other schematic diagrams of the transflective display device100of the first exemplary embodiment of the present invention in the transflective mode.FIG. 8illustrates the transflective display device100of the first exemplary embodiment when switching from the reflection mode to the transflective mode. As shown inFIG. 8, the initial voltage of the collector24and the transparent electrodes26are zero, and the initial voltage of the gate electrode25is 9V to keep the opaque charged particles232on the transparent electrodes26. Then, the settings of voltage are adjusted as follows: the collector24is supplied with a voltage of −6V, the voltage of the gate electrode25is zero, and the four transparent electrodes26are provided with voltages of 3V, −6V, −9V, −12V, respectively. Accordingly, in the present invention, a portion of the opaque charged particles232are driven to the collector24by the electric field generated by the voltage difference between the transparent electrode26with higher voltage and the collector24. Additionally, a portion of the opaque charged particles232are driven to the other transparent electrodes26by the electric field generated by the voltage difference between the transparent electrode26with higher voltage and the other transparent electrodes26with lower voltage. Moreover, the opaque charged particles232are dispersed uniformly on the three transparent electrodes26by the electric field generated by the voltage difference between the two neighboring transparent electrodes26. Subsequently, the settings of voltage are adjusted as follows: the gate electrode25is supplied with a voltage of 9V, and the voltage of the collector24and all of the transparent electrodes26are zero, so as to keep the opaque charged particles232on the transparent electrodes26. Accordingly, as shown inFIG. 9, in the transflective mode, a portion of the transparent electrodes26is covered with a plurality of the opaque charged particles232for reflecting the ambient light L2, and the backlight L1passes through the transparent electrodes26uncovered by the opaque charged particles232to reach the liquid crystal panel30. In other words, the display region D has both of the reflective region and the transmission region in this exemplary embodiment. Particularly, the two exemplary embodiments inFIG. 9andFIG. 7are both in the transflective mode, but the ratio of the area of the reflective region to the area of the transmission region is different. More specifically, the ratio of the area of the reflective region to the area of the transmission region can be arranged on the basis of the difference of the operational environment conditions.

The transflective display device of the present invention is not limited to the first exemplary embodiment. To simplify the explanation and to clarify the comparison, in the following exemplary embodiments, the same components are denoted by the same numerals, and the differences are mainly discussed while the similarities are not described again. Please refer toFIG. 10.FIG. 10illustrates a schematic diagram of a transflective display device200according to a second exemplary embodiment of the present invention. One of the differences between the first exemplary embodiment and the second exemplary embodiment is that the liquid crystal layer33is different. The second exemplary embodiment utilizes twisted nematic (TN) liquid crystal layer as the liquid crystal layer33. To comply with the TN liquid crystal layer, in the second exemplary embodiment of the present invention, the disposition of the ¼ wave plate is unnecessary, and the first polarizer41is disposed above the opaque charged particles232which are able to reflect light. More specifically, the first polarizer41in the second exemplary embodiment is disposed on the surface of the second substrate22facing the first substrate21. Additionally, another difference between the first exemplary embodiment and the second exemplary embodiment is that the first substrate21of the electrophoretic device20is the same substrate as the array substrate31of the liquid crystal panel30. In the other words, the collector24, the gate electrode25and the transparent electrodes26are disposed on the substrate nearby the liquid crystal panel30. Accordingly, in the second exemplary embodiment, the electric field profile provided by the collector24, the gate electrode25and the transparent electrodes26are also utilized to change the distribution of the opaque charged particles232based on the environmental condition for switching the corresponding pixel region mode to the most adequate display mode (transmission mode, reflection mode, or transflective mode) for the best display quality.

In conclusion, in the transflective display device of the present invention, the electrophoretic device has the opaque charged particles, the collector, the gate electrode and the transparent electrodes disposed therein and the electrophoretic device is disposed between the backlight module and the liquid crystal panel. Moreover, the present invention utilizes the electric field profile from the collector, the gate electrode and the transparent electrodes for changing the distribution of the opaque charged particles. Accordingly, based on the environmental condition, the pixel regions of the transflective display device are able to be operated in any one of display modes including transmission mode, reflection mode and transflective mode for providing better display quality. Furthermore, in the transflective mode, the ratio of the area of the reflective region to the area of the transmission region can be arranged by the electric field profile provided by the collector, the gate electrode and the transparent electrodes to meet the requirements of the various operational environments.