1. Field of Invention
The invention relates to a display device and a backlight module thereof and, in particular, to a liquid crystal display device and a backlight module thereof.
2. Related Art
In general, since flat display devices are thin, low weight and low power consumption, they are increasingly being used in various applications. Among the various types of flat panel display devices, liquid crystal display devices are widely used for cellular phones, personal digital assistants, portable personal computers, monitors, and liquid crystal televisions, etc. because of their superiority in resolution, color image display, weight, contrast and display quality.
LCD devices use the optical anisotropy by an electric field that is applied across the liquid crystal molecules to produce a predetermined image. A specific orientation can be modified by the electric field that is applied across the liquid crystal molecules. By controlling the applied voltage, the LCD device provides various transmittances for rays of light to display image data.
As shown in
However, there are two disadvantages in the conventional large-sized liquid crystal display 1. First, because the prisms of the prism sheet 12 all have the same shape and the same size, the degree of light convergence of the light may be constant. If the demand of wide view angle is satisfied, the emitted light may be scatted, so that the brightness of the central portion is not high enough. On the other hand, if the demand of brightness of the central portion is satisfied, the view angle of the liquid crystal display 1 may not be wide enough. So, the conventional large-sized liquid crystal display 1 couldn't have both advantages of high brightness in the central portion and wide view angle at the same time. Second, because of the shape (L shape or shape) and the size of the light source 14, dark bands may appear easily at the side portions of the liquid crystal display 1. So, luminance uniformity of the liquid crystal display 1 may be decreased.
In view of the above, the invention is to provide a liquid crystal display device and a backlight module thereof could adjust the emitting angle and the emitting direction of the light emitted from the backlight module.
Therefore, to achieve the above, a backlight module according to the invention comprises an optical film substrate and at least one light source. In this case, the optical film substrate has a first surface and a second surface opposite to the first surface. The first surface of the optical film substrate has at least one fresnel area. The light source is disposed at one side of the optical film substrate.
To achieve the above, a liquid crystal display device according to the invention comprises a liquid crystal module, an optical film substrate and at least one light source. In this case, the optical film substrate has a first surface and a second surface opposite to the first surface. The first surface of the optical film substrate has at least one fresnel area. The light source is disposed at one side of the optical film substrate, and the optical film substrate is disposed between the liquid crystal module and the light source.
As mentioned above, the liquid crystal display device and the backlight module according to the invention could control the emitting angle and the emitting direction of the light emitted from the backlight module. Compare to the prior art, the liquid crystal display device and the backlight module according to the invention have the fresnel area with at least one focal point. So, the invention could control the emitting angle and the emitting direction of the emitted light to satisfy the need of brightness and view angle in many different cases. Take a liquid crystal TV for an example, the invention could both satisfy the need of wide view angle and high brightness. Moreover, the invention could solve the problem that the dark bands appear at the side portions of the liquid crystal display device in the conventional large-sized liquid crystal display. Furthermore, the invention may increase the uniform of the liquid crystal display device.
The invention will become more fully understood from the detailed description given hereinbelow illustration only, and thus is not limitative of the present invention, and wherein:
The liquid crystal display device and the backlight module thereof will be described below with reference to relevant drawings.
For describing easily and clearly, the embodiments will be described below with the partially enlarged schematic views.
Please refer to
The backlight module 2 according the present embodiment further comprises a casing 23, as shown in
In the present embodiment, the optical film substrate 21 may be a flexible substrate or a rigid substrate. The optical film substrate 21 may also be a plastic substrate or a glass substrate. Herein, the plastic substrate or the flexible substrate may be a polycarbonate (PC) substrate, a polyester (PET) substrate, a cyclic olefin copolymer (COC) substrate or a metallocene-based cyclic olefin copolymer (mCOC) substrate.
In the present embodiment, the first surface 211 of the optical film substrate 21 has at least one fresnel area 2111, and the fresnel area 2111 has at least one focal point. Please refer to
In the present embodiment, when the light passes through the fresnel area 2111, the emitting angle of the light is relative to the relative position between the light source 22 and the focal point of the fresnel area 2111. In the present embodiment, the optical path may be same as, but not limited to, the optical path as shown in
Furthermore, as shown in
Moreover, the first surface 211 of the optical film substrate 21 may also have a plurality of fresnel areas 2111. As shown in
In the present embodiment, the fresnel area 2111 may be a linear fresnel lens. Furthermore, the shape and the size of the fresnel area 2111 may be adjusted by the real need.
In addition, as shown in
In the present embodiment, the shape of the light source 22 may be a linear light source or a U shape light source, and the like. In addition, the light source 22 of the present embodiment may be a fluorescent tube (for example, a cold cathode fluorescent lamp, CCFL), a light-emitting diode array (LED array) or an organic light emitting diode (OLED), and the like.
In the present embodiment, a quantity of the light source 22 is substantially equal to a quantity of the fresnel area 2111, and the position of the light source 22 is related to the position of the fresnel area 2111. For example, when the backlight module 2 has a plurality of light sources 22, each light source 22 is disposed near the central portion of each fresnel area 2111, as shown in
Moreover, the backlight module 2 of the present embodiment may be mixed with diffusion powder. In the present embodiment, the optical film substrate 21 may be mixed with diffusion powder. In the present embodiment, the diffusion powder may correct the emitting angle of the emitted light and may also enhance the scattering effect so that the backlight module 2 may form the uniform surface light.
Please refer to
In addition, as shown in
Moreover, the second surface 212 of the optical film substrate 21 has at least one pattern (for example, dot pattern, prismatic pattern or notch). The pattern may enhance the scattering effect and may also decrease the reflecting effect of the light. The pattern may also increase the diffusion effect. In the present embodiment, the pattern is on the surface of the optical film substrate 21.
In addition, the backlight module 2 of the present embodiment further comprises a reflector 26. Herein, the reflector 26 may be disposed on the casing 23 and may be disposed between the light source 22 and the casing 23. In the present embodiment, the reflector 26 may reflect the scattering light to the optical film substrate 21 so that the reflector 26 may increase the utilization of the light and may also increase the brightness of the backlight module 2. Herein, the reflector 26 may be made of, but not limited to, Aluminum (Al).
In the present embodiment, the backlight module 2 may be, but not limited to, a backlight module of a liquid crystal display.
As shown in
In the present embodiment, the liquid crystal display 3 further comprises a casing 34, a diffuser 35 and a reflector 36.
In the present embodiment, the characteristics and functions of the optical film substrate 32, the light source 33, the casing 34, the diffuser 35 and the reflector 36 are the same as the same elements in the first embodiment, and detailed descriptions thereof will be omitted.
In addition, the liquid crystal module 31 of the present embodiment includes a first polarizing plate 311, a filter 312, a first electrode 313, a liquid crystal layer 314, a thin film transistor (TFT) 315 and a polarizing plate 316. Herein, the elements of the liquid crystal module 31 may be adjusted by the real need.
As shown in
Furthermore, the fresnel area 3211 has at least one focal point. Herein, because the fresnel area 3211 has two focal points (as shown in
As mentioned above, the liquid crystal display device and the backlight module according to the invention could control the emitting angle and the emitting direction of the light emitted from the backlight module. Compare to the prior art, the liquid crystal display device and the backlight module according to the invention have the fresnel area with at least one focal point. So, the invention could control the emitting angle and the emitting direction of the emitted light to satisfy the need of brightness and view angle in many different cases. Take a liquid crystal TV for an example, the invention could both satisfy the need of wide view angle and high brightness. Moreover, the invention could solve the problem that the dark bands appear at the side portions of the liquid crystal display device in the conventional large-sized liquid crystal display. Furthermore, the invention may increase the uniform of the liquid crystal display device.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.
Number | Date | Country | Kind |
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093116460 | Jun 2004 | TW | national |