Screen for projection television

#1. Field of the Invention

#The present invention relates to a projection television and, more particularly, to a screen of a projection television having a high brightness.

#2. Description of the Related Art

#The above aspects and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:

#FIG. 1 is a perspective view showing the structure of a conventional projection television screen;

#FIG. 2 is a cross sectional view of the Fresnel lens of FIG. 1 vertically crossing the center of the Fresnel lens 11;

#A projection television screen according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings, the thickness of a layer or area is shown to be greater than the actual thickness for the convenience of explanation.

#Referring to FIG. 4, a screen of a projection television according to an exemplary embodiment of the present invention may include a Fresnel lens 36 for converting an incident light beam from an image source (not shown) of a projection apparatus (not shown) into a parallel beam, a lenticular lens 38 formed of a plurality of lens elements having a column shape which are arranged consecutively, for forming an image from the parallel beam input from the Fresnel lens 36 and spreading the image, and a protective panel (not shown) installed at the front surface of the lenticular lens 38 for protecting the lenticular lens 38. The Fresnel lens 36 may include a base substrate 40 and a lens unit 42 contacting one side of the base substrate 40. The base substrate 40 and the lens unit 42 may be formed of different materials to increase a change of an optical path passing through the base substrate 40 and the lens unit 42. That is, the refractive index of the base substrate 40 may be different from that of the lens unit 42. By doing so, a light beam 44 emitted from the image source such as a Cathode Ray Tube (CRT), Liquid Crystal Display (LCD) or other image display device is incident on the base substrate 40 and then primarily refracted in a predetermined direction according to Snell's rule. The primarily refracted light beam is incident on the lens unit 42 and then refracted secondarily in a predetermined direction according to Snell's rule.

#Thus, as the light beam 44 emitted from the image source is sequentially refracted by the base substrate 40 and the lens unit 42 to greatly change the optical path of the light beam 44, an incident angle of the light beam incident on the exit surface of the lens unit 42 is reduced compared to the conventional technology. That is, the incident angle of the light beam incident on the exit surface is smaller than the critical angle at which total internal reflection occurs so that most of the light incident on the lens unit 42 passes through the lens unit 42 in a predetermined direction. Accordingly, loss of light due to the total internal reflection when the light beam passes through the lens unit 42 is minimized. To obtain such a result, the refractive index of the lens unit 42 may be greater than that of the base substrate 40.