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Transflective liquid crystal display panel, liquid crystal display module and liquid crystal display thereof

Transflective liquid crystal display panel, liquid crystal display module and liquid crystal display thereof description/claims

This application claims the benefit of Taiwan application Serial No. 95143644, filed Nov. 24, 2006, the subject matter of which is incorporated herein by reference in its entirety.

1. Field of the Invention

The invention relates in general to a transflective liquid crystal display (LCD), and more particularly to a transflective LCD having a transmissive pixel and a reflective pixel, which are respectively controlled by different pixel voltages.

2. Description of the Related Art

In a conventional transflective liquid crystal display (LCD), such as a vertically-aligned (VA) mode transflective LCD, each pixel has a pixel electrode and a reflective electrode electrically connected to each other. The pixel electrode and the reflective electrode respectively form a transmissive region and a reflective region, and the pixel electrode and the reflective electrode are driven by the same pixel voltage. As for the transmissive region, the pixel voltage influences the transmittance rate of backlight passing through a liquid crystal layer in the transmissive region. As for the reflective region, the pixel voltage influences the transmittance rate of environmental light passing through the liquid crystal layer in the reflective region, it is emitted from an environment light source, incident to the liquid crystal layer and then reflected outward by a reflective layer.

The relationship between the pixel voltage and the transmittance rate in the transmissive region, and the relationship between the pixel voltage and the transmittance rate in the reflective region respectively form different voltage-transmission (V-T) curves. Usually, both of the maximum transmittance rates of the V-T curve of the transmissive/reflective region are defined as 100%. FIG. 1 depicts V-T curves of a transmissive region and a reflective region in a conventional transflective LCD.

As shown in FIG. 1, curve 101 is the V-T curve in the transmissive region and curve 102 is the V-T curve in the reflective region. When the pixel voltage is higher than a threshold voltage|, the transmissive region and the reflective region start to respectively generate transmittance rate variations. At the same pixel voltage V, the transmittance rate Lt and the transmittance rate Lr, respectively corresponding to the transmissive region and the reflective region are not the same, such that the gray levels of the transmissive region and the reflective region are different from each other and the trends of the two curves are also different from each other. Therefore, in the pixel structure of the conventional transflective LCD, it is difficult for one pixel voltage V to make the transmissive region and the reflective region display the same gray level. Therefore, the transmissive region and the reflective region in one pixel cannot simultaneously reach the desired displaying effect.

For example, one image has to be displayed by four pixels A, B, C and D having different gray levels. However, the same set of pixel voltages are used, so it is impossible to make the transmissive region and the reflective region simultaneously display the four same gray levels. The above-mentioned problem may be solved in the conventional transflective LCD by designing the transmissive region and the reflective region to have different cell gaps (also referred to as a “dual cell gaps”), for example, the cell gap of the reflective region is about one half that of the transmissive region. However, the manufacturing processes are complicated and expensive.

Operationally, the light source of the reflective region comes from the outside environment. When the environmental light source changes, for example, when the light source changes from the outdoor sunlight to the indoor daylight lamp, or when the sunlight changes with time, the brightness and the color presented by the reflective region also change. The color is the result obtained after the light passes through the color filter. However, the light of the transmissive region only comes from the backlight source, and its brightness and color cannot change with the change of the environmental light. Therefore, if the transmissive region and the reflective region are driven by the same pixel voltage, the brightness or colors co-presented by the transmissive region and the reflective region often deviate from the optimum settings, which are set when the product is finished and ready to be shipped out, so that the incongruent condition is obtained when the environmental light changes with the changes of the time and the environment.

Therefore, it is an important subject in the industry to make the displayed gray level generated by the transmissive light the same as the displayed gray level generated by the reflective light inan LCD. It is further important that the brightness and the color representation of the reflective region are not changed with the variation of the environmental light so that the image displaying quality can be enhanced.

The invention is directed to a transflective LCD having a transmissive pixel and a reflective pixel respectively driven by a transmissive pixel voltage and a reflective pixel voltage. Independently controlling the transmissive pixel and the reflective pixel allows the brightness or the gray level displayed by the transmissive pixel and the reflective pixel to achieve a desired effect, thereby enhancing the image displaying quality.

According to a first aspect of the present invention, a transflective LCD panel including a liquid crystal layer, scan lines, data lines, transmissive pixels and reflective pixels is provided. The data lines are disposed substantially perpendicular to the scan lines. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines, receives a transmissive pixel voltage transmitted from one of the data lines to drive a first portion of liquid crystal layer, and displays a first gray level related to the transmissive pixel voltage. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines, receives a reflective pixel voltage transmitted from one of the data lines to drive a second portion of liquid crystal layer, and displays a second gray level related to the reflective pixel voltage. When the first transmissive pixel and the first reflective pixel are used to display the same gray level, the received transmissive pixel voltage and the reflective pixel voltage are such that the corresponding first and second gray levels are substantially equal to each other.

According to a second aspect of the present invention, a transflective LCD, including a backlight element, a liquid crystal layer, scan lines, data lines, transmissive pixels and reflective pixels is provided. The backlight element provides a backlight source. The data lines are disposed substantially perpendicular to the scan lines. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines, receives a transmissive pixel voltage transmitted from one of the data lines to drive a first portion of liquid crystal layer, and displays a first gray level related to the transmissive pixel voltage. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines, receives a reflective pixel voltage transmitted from one of the data lines to drive a second portion of liquid crystal layer, and displays a second gray level related to the reflective pixel voltage. When the first transmissive pixel and the first reflective pixel are used to display the same gray level, the received transmissive pixel voltage and the reflective pixel voltage are such that the corresponding first and second gray levels are substantially equal to each other.

According to a third aspect of the present invention, a transflective LCD module including a liquid crystal layer, scan lines, data lines, at least one driving circuit, a photosensor unit, transmissive pixels and reflective pixels is provided. The driving circuit drives the scan lines and the data lines. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines and receives a transmissive pixel voltage transmitted from one of the data lines to drive a first portion of liquid crystal layer. Backlight emitted from a backlight source passes through the first transmissive pixel at a first transmittance rate related to the transmissive pixel voltage. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines and receives a reflective pixel voltage transmitted from one of the data lines to drive a second portion of liquid crystal layer. Environmental light is incident to and reflected by the first reflective pixel at a second transmittance rate related to the reflective pixel voltage. The photosensor unit senses a spectrum of the environmental light and is electrically connected to the driving circuit. When the first transmissive pixel and the first reflective pixel are used to display the same original gray level, the driving circuit adjusts the original gray level into an adjusted gray level according to the spectrum sensed by the photosensor unit, and generates the reflective pixel voltage according to the adjusted gray level, such that the first transmissive pixel and the first reflective pixel respectively generate the same brightness.

According to a fourth aspect of the present invention, a transflective LCD includes a backlight element, a liquid crystal layer, scan lines, data lines, at least one driving circuit, a photosensor unit, transmissive pixels and reflective pixels. The backlight element is for providing a backlight source. The driving circuit is for driving the scan lines and the data lines. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines, and receives a transmissive pixel voltage transmitted from one of the data lines to drive a first portion of liquid crystal layer. Backlight emitted from the backlight source passes through the first transmissive pixel at a first transmittance rate related to the transmissive pixel voltage. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines, and receives a reflective pixel voltage transmitted from one of the data lines to drive a second portion of liquid crystal layer. Environmental light is incident to and reflected by the first reflective pixel at a second transmittance rate related to the reflective pixel voltage. The photosensor unit senses a spectrum of the environmental light, and is electrically connected to the driving circuit. When the first transmissive pixel and the first reflective pixel are used to display the same original gray level, the driving circuit adjusts the original gray level into an adjusted gray level according to the spectrum sensed by the photosensor unit, and generates the reflective pixel voltage according to the adjusted gray level such that the first transmissive pixel and the first reflective pixel respectively generate the same brightness.

According to a fifth aspect of the present invention, a transflective LCD panel includes a liquid crystal layer, scan lines, data lines, transmissive pixels and reflective pixels. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines and receives a transmissive pixel voltage transmitted from one of the data lines to drive a first portion of liquid crystal layer. Backlight emitted from a backlight source passes through the first transmissive pixel at a first transmittance rate related to the transmissive pixel voltage. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines and receives a reflective pixel voltage transmitted from one of the data lines to drive a second portion of liquid crystal layer. Environmental light is incident to and reflected by the first reflective pixel at a second transmittance rate related to the reflective pixel voltage. A resolution of the transmissive pixels is unequal to a resolution of the reflective pixels.

According to a sixth aspect of the present invention, a transflective LCD includes at least one backlight element, a liquid crystal layer, scan lines, data lines, transmissive pixels and reflective pixels. The backlight element provides a backlight source. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines and receives a transmissive pixel voltage transmitted from one of the data lines to drive a first portion of liquid crystal layer. Backlight emitted from the backlight source passes through the first transmissive pixel at a first transmittance rate related to the transmissive pixel voltage. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines and receives a reflective pixel voltage transmitted from one of the data lines to drive a second portion of liquid crystal layer. Environmental light is incident to and reflected by the first reflective pixel at a second transmittance rate related to the reflective pixel voltage. A resolution of the transmissive pixels is unequal to a resolution of the reflective pixels.

According to a seventh aspect of the present invention, a transflective LCD panel includes scan lines, data lines, a first liquid crystal layer, a second liquid crystal layer, transmissive pixels and reflective pixels. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines and receives a transmissive pixel voltage transmitted from one of the data lines to drive the first liquid crystal layer. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines and receives a reflective pixel voltage transmitted from one of the data lines to drive the second liquid crystal layer. The liquid crystal molecules of the first liquid crystal layer and the liquid crystal molecules of the second liquid crystal layer pertain to different aligned modes.

According to an eighth aspect of the present invention, a transflective LCD includes a backlight element, scan lines, data lines, a first liquid crystal layer, a second liquid crystal layer, transmissive pixels and reflective pixels. The backlight element provides a backlight source. The transmissive pixels include a first transmissive pixel. The first transmissive pixel is controlled by one of the scan lines and receives a transmissive pixel voltage transmitted from one of the data lines to drive the first liquid crystal layer. The reflective pixels include a first reflective pixel. The first reflective pixel is controlled by one of the scan lines and receives a reflective pixel voltage transmitted from one of the data lines to drive the second liquid crystal layer. The liquid crystal molecules of the first liquid crystal layer and the liquid crystal molecules of the second liquid crystal layer pertain to different aligned modes.

According to a ninth aspect of the present invention, a transflective LCD panel for generating a frame in a frame time is provided. The transflective LCD panel includes scan lines, data lines, transmissive pixels and reflective pixels. Each transmissive pixel is controlled by one of the scan lines and receives transmissive pixel voltages transmitted from one of the data lines. Several colors of backlight, sequentially emitted from a backlight source, sequentially pass through each transmissive pixel to make each transmissive pixel sequentially display several colors in the frame time. Each reflective pixel is controlled by one of the scan lines and receives a reflective pixel voltage transmitted from one of the data lines. Environmental light is reflected by a first reflective pixel.

According to a tenth aspect of the present invention, a transflective LCD for generating a frame in a frame time is provided. The transflective LCD includes a backlight element, scan lines, data lines, transmissive pixels and reflective pixels. The backlight element provides a backlight source. Each transmissive pixel is controlled by one of the scan lines and receives transmissive pixel voltages transmitted from one of the data lines. Several colors of backlight, sequentially emitted from the backlight source, sequentially pass through each transmissive pixel to make each transmissive pixel sequentially display several colors in the frame time. Each reflective pixel is controlled by one of the scan lines, and receives a reflective pixel voltage transmitted from one of the data lines. Environmental light is reflected by a first reflective pixel.

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