Patent Application
20070171379
1. Field of the Invention
The present invention relates to a system of enhancing contrast of display screen for a projector, and more especially, to a projection system of changing environment influence on display screen.
2. Background of the Related Art
In recent years, the technology development has a tendency to combine the products of display and projector such as liquid crystal display projector, digital light processing (DLP), and liquid crystal on silicon (LCOS), etc.
Generally, the main components of a projector are light source module, light management module, and image projection module. Referring to
Conventionally, a quarter wave plate 127 is placed before the light plate of the light management module to change the stray light of light management module. Nevertheless, the stray light outside the light management module is also one factor of the light leakage in dark field. And it can't be improved by modifying the light management module.
To change the light leakage in dark field induced by the environmental stray light for PBS, a component in one embodiment of this invention is provided. This component, which is placed between the light management module and the lenses of image projection module, may prevent the stray light reflected by the lenses of image projection module from entering into the light light management module or coming back into the lenses of image projection module.
To increase the output image contrast of display screen from a projector, a structure in one embodiment of this invention is provided. This structure for eliminating the light leakage in dark field utilizes a reflecting element placed between the light management module and the lenses of image projection module. The reflecting element reflects the stray light reflected by the lenses of image projection module in various directions to the area outside the lenses of image projection module, thereby reducing the dark field brightness.
To improve the output image contrast from a projector, a component in one embodiment of this invention is provided. This component for reducing the dark field brightness applies a reflecting lens placed before the light management module, which can prevent the environmental stray light from entering into the light plate of the light management module by reflecting the environmental stray light to the outside area of the light management module.
Accordingly, one embodiment of the present invention provides the projection system of preventing the environmental stray light. Reflecting means is placed between the light management module and the lenses module. The reflecting means is configured for preventing the environmental stray light coming from the lenses module from entering into the light management module.
Referring to
In the second embodiment, the reflecting device 18 may be one kind of a reflecting material attached on the lens surface that receives the light inputted from the light management module 14 in the lenses module 16. For example, the reflecting material Ag or Al is coated on the lens surface facing the light management module 14. Referring to the third embodiment in the
Referring to the fourth embodiment in the
For projection equipment, the contrast is defined as the ratio of the brightness of white field to the brightness of dark field. The brightness of white field is dependent on the light source, such as its emitting efficiency and power, etc. Accordingly, although it is possible to increase the contrast by raising the brightness of white field, the contrast increase is limited owing to the aforementioned factors affecting the brightness of white field. On the other hand, it is also possible to increase the contrast by decreasing the brightness of dark field. According to the above description, one feature of this invention is to prevent or block the environmental stray light to decrease the brightness of dark field and so as to increase the contrast. Furthermore, observer is more sensitive to the contrast change than the brightness change of the screen. The spirit of this invention is to sacrifice little brightness to reward large contrast increase. Since, the setting of reflecting device may decrease little brightness, but increase large contrast and in such a way to elevate the display efficiency of screen.
Accordingly, one embodiment of the present invention provides the projection system of preventing the environmental stray light Reflecting means is placed between the light management module and the lenses module. The reflecting means is configured for preventing the environmental stray light coming from the lenses module from entering into the light management module. Another embodiment of the present invention provides the projection system of changing the brightness of dark field. A lenses module receives a beam output through said light management module from said light source. The position of the reflecting means results in the light management module placed between the light source and the reflecting means and is configured for reflecting light coming from the lenses module.
Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that other modifications and variation can be made without departing the spirit and scope of the invention as hereafter claimed.
