Abstract:
Embodiments of the invention relate to a reflective projection screen for image, and more particularly, to a shape and a fabrication method for a reflective projection screen for a projector having short focal length of short projection distance, and particularly to a reflective projection screen applicable to 2D and 3D. In particular, embodiments of the present invention relates to a reflective projection screen having multi-incident angle wherein every reflection surface is prepared per projection angle of projection image and incident angles are formed differently from each reflection surfaces so that the projection images from different angles are reflected into one direction.

Description:
CROSS-REFERENCE(S) TO RELATED APPLICATION 
       [0001]    This application claims priority of Korean Patent Application No. 10-2010-0066698, filed on Jul. 12, 2010, in the Korean Intellectual Property Office, which is hereby incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a reflective projection screen for image, and more particularly, to a method of fabricating a reflective projection screen for a projector having short focal length of short projection distance and a shape thereof, which is applicable to 2D and 3D. In particular, embodiments of the present invention relates to a reflective projection screen having multi-incident angle wherein every reflection surface is prepared per projection angle of projection image and incident angles are formed differently from each reflection surfaces and further the reflection surface has no reflection layer so that the projection images projected from different angles are reflected into one direction. 
         [0004]    2. Description of the Related Art 
         [0005]    Generally, a 2 dimension (2D) image refers to as a plain moving picture or a video image. Meanwhile, a 3 dimension (3D) image refers to as a cubic image and there are two ways of showing the cubic image using a projector. That is, the one is polarizing way that the images are projected through left-right polarizing plates provided before projection lens of two left and right projectors and the images are viewed through a 3D glass provided with left and right polarizing plates. The other is a glass-shutter way that left image and right image are projected alternatively in sequence from a projector and then a 3D glass receives the alternative signals to open and close alternatively the left and right glass lens through the left and right images on a screen and synchronizing signal in a glass, thereby the cubic image to be viewed. 
         [0006]    However, referring to the polarizing manner as described above the image has to be reached to the polarizing glass in a state of polarization degree being maintained to view 3D image and further, referring to the glass shutter manner the shutter is driven to view 3D image such that signal such as infrared light from a projector has to be projected to a screen and be reflected from the screen to reach a infrared light sensor provided in the 3D glass. For this reason, referring to the polarizing manner which is usually used in a theater, the screen for receiving polarization degree is limited extremely and thus 2D and 3D theater has to be separately prepared due to the screen. 
         [0007]    In case of the polarizing manner only 25% of image in light is transmitted through a polarizing plate of a projector and 25% of image in light is transmitted through 3D glass and thus only 12.5% of image in light is viewed on the screen. Accordingly, the polarization degree decreases to 12.5%. 
         [0008]    Meanwhile, in case of 3D image according to the shutter manner, since left and right images are projected in sequence alternatively from a projector, 50% of image in light is transmitted, that is transmission rate is 50%, and 30% of image in light is transmitted through shutter glass and thus 15% of image in light is viewed on a screen. Accordingly, the infrared light signal of synchronizing signal for the shutter decreases dramatically to 15%. For this reason, brightness of 3D image decreases to lower dramatically definition thereof and thus 3 dimensional feeling. Furthermore, when a user views the dark image for a long time, he/she feels tired in his/her eyes and headache, and thus there is need to develop brighter screen. 
         [0009]    Here, U.S. Pat. No. 7,227,683 and U.S. Pat. No. 7,362,502, which were filed by the present applicant, disclose the reflective screen and spherical screen which are considered to be as 20 times bright as conventional screen wherein as shown in  FIG. 6 , when a projector is placed on a focal point (f) of a spherical screen  1   a , image is reflected straightly from the spherical screen  1   a  and thus a reverse angle range (e) is enlarged to an entire screen size, thereby diminishing a hot spot appearance and increasing prominently brightness uniformity. 
         [0010]    The spherical screen  1   a  is applied efficiently to 3D cubic image as well as 2D image, however, when a projector of a short focal distance is used, a radius of curvature formed by a short focal point limits to a screen size. That is, as shown in  FIG. 5 , a focal distance (projection distance) f is r/2, and thus r=2f. Accordingly, when f becomes shorter, r becomes small and thus a screen size g becomes smaller. Therefore, the screen size is to be determined within the range g formed by 2 times curvature having the projection distance of the projector having a short focal distance point, which considers to project in a short distance, and thus the picture size decreases as much as the projection distance is shortened, and it makes large size screen configuration to be impossible. 
         [0011]    Additionally, referring to the spherical screen a thin film screen which is rolled up such as a roll screen is impossible due to a curvature depth of a spherical surface. Here, it has been also disclosed that a screen configuration using Fresnel reflection refracts or reflects images by a prism configuration wherein the image has to be transmitted through a prism medium for refraction and even when a reflection surface is provided on a rear surface thereof, the image has to be transmitted through the prism medium for a reflection. Here, it has been also disclosed that when the image is transmitted through the prism medium, a refraction rate of polarization degree varies and thus it cannot be applied to 3D image. In particular, in the Fresnel configuration, as shown in  FIG. 14 , it has been disclosed in “Optical” in page 374 (translation by Kwon Yong Dae) that it recedes by a half-wave from point p and thus a picture size cannot be enlarged in contrast to the focal point distance. Accordingly, the screen thickness may be formed as a thin film in the Fresnel configuration, however, the larger screen than the focal point distance cannot be fabricated. 
         [0012]    Therefore, the screen using Fresnel reflection, as shown in  FIG. 6 , cannot be applied to a projector having a short focal distance under a large screen, as same as in the present invention. 
         [0013]    That is, since the projector having a short focal distance has to be placed on a middle axe of Fresnel for an normal operation, it has to be applied to a transmissive screen However, when the projector having a short focal distance is placed on a middle part of a screen, the image is sight-blocked and thus it cannot practical. In particular, when the image is transmitted through transmissive medium of Fresnel, polarization degree of cubic 3D image is collapsed and thus it has limitation to using as a 3D screen. 
         [0014]    Additionally, Korean Patent Application No, 10-2003-0051853, which was filed by the present applicant, discloses a high refraction reflective screen, as shown in  FIG. 7  wherein the images incident from several angles are not reflected straightly at same angle but reflected themselves in diffusion manner to incident direction. Accordingly, reverse angle e of a reflection angle to a screen height is small and thus a hot spot phenomenon in which a part of the screen is shown brightly is occurred prominently. Additionally, reflection angles are diffused depending on incident angles and it acts as mirror which changes reflection direction and thus brightness uniformity is too poor and picture brightness is different depending on the reflection angle, thereby making it impossible to be used as a screen. In particular, a polarization degree of polarized 3D image is diffused and thus it can be used finitely as a 3D cubic screen. 
         [0015]    Meanwhile, referring to a projection distance of a general projector, the projection distance is 4-5 m based on a lateral length 2 m of the screen and thus a ratio of the projection distance to the lateral length of the screen is 2-2.5:1. 
         [0016]    However, when the projection distance becomes longer as described above, there arises a problem in that the projector and the screen are arranged separately and further the prior projector having a long projection distance occupies a large installation area, thereby installing it home to be difficult. 
       SUMMARY OF THE INVENTION 
       [0017]    Embodiments of the invention are proposed to solve the drawbacks as described above of the prior art, and one object of the invention relates to provide a reflective projection screen having multi-incident angles and more particularly, to a method of fabricating a reflective projection screen of a projector having short focal length of a short projection distance a shape thereof, and particularly to a reflective projection screen applicable to 2D and 3D. 
         [0018]    Recently, a projector having a projection distance of 30-50 cm which is 0.15-0.2:1 of the projection distance to a picture lateral length, based on a screen lateral length of 2 m, has been proposed in a market. The projection distance of 30-50 cm refers to as 1/5-1/10 level. Here, the short focal point projector minimizes a distance between a screen and the projector and thus it may be installed and used conveniently. However, a projection angle thereof is large and wide and thus it has to be applied only to a prior scattered screen of less than 1 gain and not to a conventional reflective screen and spherical screen in which brightness increases. 
         [0019]    Meanwhile, referring to a general screen  1   a , as shown in  FIG. 1 , Snell reflection rule of “an incident angle a equals to a reflective angle b reflected from a screen” is applied thereto. That is, in a prior projector  2   a , as shown in  FIG. 2 , a ratio of a projection distance to a picture lateral length is about 2-2.5:1, which considers the projection distance to be long. Accordingly, the incident angle a and the reflection angle b are small and thus light projected from the general projector  2   a  is reflected easily to a viewer or a location of a cubic glass D. 
         [0020]    However, according to an embodiment of the present invention as shown in  FIG. 3 , a main light source of a short focal point projector  2  placed under a plane reflective screen  1   a  is reflected from the reflective screen toward a ceiling location and thus dark image may be viewed in 2D and further cubic image cannot be viewed since an image reflection angle is beyond cubic glass location. 
         [0021]    Furthermore, there is a problem of a prior plane reflective screen in that spot phenomenon in which bright part is appeared partly and moved through a whole surface is occurred. This spot occurrence makes it impossible as a screen since a bright light source projected from a projector lamp is not diffused due to a reflective surface and reflected directly on the screen. 
         [0022]    Accordingly, in order to eliminate the hot spot appearance as described above and further achieve brightness uniformity of the screen through a spherical screen, the projector  2  according to one embodiment of the present invention, having a short focal point distance of 0.2-0.5 times of picture size, has to be placed on a focal point of the spherical screen having a curvaturer. Therefore, the picture size is limited to within the curvature r formed by the projection distance of a projector and the projection distance of the short focal distance projector  2  becomes small as 1/5 to 1/10 times as the prior art and thus the picture size becomes small 1/5 to 1/10 times as the prior screen size. 
         [0023]    Additionally, a spherical surface of smooth curvature r having more than 2-6 times of the projection distance as the picture size has to be formed to show a projection image of plain image on a screen. However, in case of a spherical screen having a short projection distance the curvature r becomes deep as much as shorter projection distance and image distortion is occurred, thereby not being applied as 2D image or 3D image screen. 
         [0024]    Accordingly, the object of the present invention cannot be achieved through a configuration of the prior spherical reflective screen and thus it needs a novel reflective screen configuration through which brightness on the screen is increased and hot spot appearance is eliminated and further polarity degree is kept. 
         [0025]    The present invention has been proposed in consideration of the points as described wherein a reflective surface with multi incident angle is provided for being applied to a projector having the short focal point projector and a large screen as more than 4 times as the projection distance of the short focal point projector is provided and further uniform bright image without the hot spot appearance can be obtained. At the same time, the object of the present invention relates to provide a reflective screen of a thin film type with multi incident angle through which brightness as 4-30 times as the prior typical screen is obtained and further 2D image and 3D image cab be shown thereon. 
         [0026]    Meanwhile, according to one embodiment of the present invention, a reflective screen of a thin film type  1  is provided and further a short focal point projector  2  having a short projection distance is provided below the screen, as shown in  FIG. 8 . Here, the screen is made as a reflective screen  1  wherein, as shown  FIGS. 9(   a ),  9 ( b ) and  10 , a height h of the reflective screen  1  is divided into several parts of 0.1-30 mm at interval to form reflective surfaces c per a finely divided line. In addition, the divided reflective surfaces c each is provided with an inclined surface having an inclined angle  3  differently from each other wherein each inclined angle  3  is accumulated from more than 1° to less than 45°, based on a location and a direction of the short focal point projector  2 , per a line of the reflective surface c. Meanwhile, as shown in  FIGS. 9(   a ),  9 ( b ),  10 ,  11 ( b ) and  12 ( b ), steps such as saw teeth of the respective inclined angle  3 , which are formed on surfaces of the plain screen, are to removed and the reflective surface c having the inclined angle  3  is transferred to a plain screen surface, and thus each 2D image or 3D image from the short focal point projector  2  which is incident from different angles is reflected straightly toward one direction of viewer or cubic glass D. 
         [0027]    Besides, as shown in  FIG. 11(   a ), the reflective surface c is configured as a circle form wherein the circle has an eccentric axe  5  from a direction of the short focal point projector  2  being placed and further a reflection rate of the reflection surface is 2-30%. Additionally, as shown in  FIG. 12(   a ), a scattering surface  4  which scatters leftward and rightward is provided on the reflective surface c and further the reflective surface c is provided on left and right direction and the projected images are divided per projection angle to reflect the projected image toward one direction wherein the reflective surface c is provided on each projection angle unit, and incident angles are different from each reflective surface c, that is, the screen has multi incident angles for both 2D and 3D images. 
         [0028]    According to one embodiment of the present invention, as indicated as g in  FIG. 5 , a short focal point projector is provided and further the projector and a screen are formed integrally and a projection distance is decreased as 1/5-1/10 times as the prior screen, thereby decreasing dramatically installation area. Furthermore, the inclined angle  3  is increased gradually with respective different incident angle a on the divided reflective surface C and thus the image projected toward a viewer or cubic glass D through the gradually accumulated incident angle a is reflected straightly and at the same time the hot spot appearance is eliminated to make brightness thereof uniform. In addition, the reflection rate of the whole screen is increased to make the screen bright as 2-30 times (2-30 gain) as the prior screen even at plain surface. 
         [0029]    Meanwhile, referring to a size of the reflective screen  1 , as shown in  FIG. 10 , the height h of the screen is divided into intervals of the reflective surface c in each size of 0.1-30 mm and several lines are made, thereby enabling a large picture to be made, regardless of the curvature r range of the prior spherical screen. As a result, a large screen more than 4 times of the prior spherical screen, with having equal projection distance. 
         [0030]    Here, unit interval of the reflective surface c is 0.1-30 mm and the inclined angles thereof are formed within 1-45°, and thus a thickness of the reflective surface C per unit can become thin configuration S, as shown in  FIG. 9(   b ), comparing to the thickness T of the prior spherical screen, as shown in  FIG. 9(   a ). That is, the thickness T of 50 cm as becoming thick as the projection distance can be decreased to 0.1-30 mm of unit interval of the reflective surface, and thus thin film configuration S as small as maximum 1/5000 times as the prior spherical screen can be obtained. 
         [0031]    Furthermore, according to another embodiment of the present invention, when the thin film screen is made of flexible material such as film, it may be a roll screen which may be rolled-up. 
         [0032]    Particularly, typical 2D or 3D image can be projected on a picture without picture distortion using the thin film screen and further through this refracted-reflective configuration the image may be refracted and reflected, comparing to a general prism through which light passes through medium having different refraction rates, on a reflective surface per each reflective surface C and thus brightness is increased with keeping polarity degree of light projected from a cubic projector. Accordingly, a shutter synchronizing signal or polarity degree for cubic image is increased to as 4-30 times as the prior screen and clearness degree of the cubic image is increased to as the same as the polarity degree and thus any cubic images and 2D images can be viewed. 
         [0033]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of embodiments of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  shows schematically an incident angle and reflective angle on a reflective screen. 
           [0035]      FIG. 2  shows schematically a projection distance of a prior projector. 
           [0036]      FIG. 3  shows schematically an incident angle and reflective angle when a short focal point projector is provided according to one embodiment of the present invention. 
           [0037]      FIG. 4  shows schematically a spherical screen and a hot spot. 
           [0038]      FIG. 5  shows schematically a size of the short focal point spherical screen and a size of the reflective screen. 
           [0039]      FIG. 6  shows schematically an operation of a Fresnel screen. 
           [0040]      FIG. 7  shows schematically a reflective operation and a hot spot appearance of a prism surface screen. 
           [0041]      FIG. 8  shows schematically a reflective screen with multi incident angles according to one embodiment of the present invention. 
           [0042]      FIG. 9(   a ) shows schematically a reflective surface and an inclined angle in the reflective screen with multi incident angle according to one embodiment of the present invention. 
           [0043]      FIG. 9(   b ) shows schematically the inclined angle shown in  FIG. 9(   a ), which is provided on a plain surface. 
           [0044]      FIG. 10  shows schematically a reflective surface and inclined angle provided on a plain surface in the reflective screen with multi incident angles according to one embodiment of the present invention. 
           [0045]      FIG. 11(   a ) shows schematically the reflective surfaces formed as eccentric circles. 
           [0046]      FIG. 11(   b ) shows schematically the reflective surface shown in  FIG. 11(   a ) transferred to a plain surface. 
           [0047]      FIG. 12(   a ) shows schematically the reflective surface according to the present invention, which is configured horizontally leftward and rightward. 
           [0048]      FIG. 12(   b ) shows schematically the reflective surface shown in  FIG. 11(   a ), which is transferred to a plain surface. 
           [0049]      FIG. 13  shows schematically a screen configuration according to one embodiment of the present invention, which is formed as thin film. 
           [0050]      FIG. 14  shows schematically Fresnel operation for reference (“Optical” in page 374 translated by Kown Yong Dae) 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0051]    The preferred embodiments of a reflective screen with multi incident angle will be described in detail referring to the accompanied drawings. However, it has to be understood that embodiments of the invention are not limited to the preferred embodiments described hereafter. 
         [0052]    The present invention relates to a reflective screen with multi incident angle wherein a reflective screen  1  formed as a thin film is provided and a short focal point projector  2  is provided on lower part of the screen, as shown in  FIG. 8 . Here, according to one embodiment of the present invention, the reflective surface C having a curvature r of a spherical screen is divided into a predetermined interval and respective reflective surface c formed in each interval is provided with an inclined surface. Meanwhile, the inclined surface is slanted at an inclined angle  3  range of 1° to 45°, which is accumulated from 1° at a location of the short focal point projector  2  being placed to less than 45°. The reasons for configuring the inclined angle  3  in an range from more than 1° to less than 45° are that a view angle from the short focal point projector  2  to the lower part of the reflective screen  1  has to be ensured for more than 1° and maximum inclined angle  3  of the reflective surface for reflecting the image incident vertically at a right angle is 45° 
         [0053]    Additionally, a reflection rate of the reflective surface c is formed as 2-30% by adjusting the left and right scattering lines so that brightness increases to as 4-30 times as the typical screen of a gain (reflection rate 1%). At this time, as the reflection rate becomes higher, the interval of the reflective surface has to become smaller, whereas the reflection rate becomes lower, the interval of the reflective surface may be larger; however, the range of the interval has to be within 0.1-30 mm. Here, the thickness s of the reflective screen with multi incident angle according to the present invention is made as the thickness formed by the inclined angle 45° which is formed through the interval 0.1-30 mm of the reflective surface c, making the screen as thin film configuration. Additionally, since the reflection rate of the reflection surface c is 2-30%, the remaining surface 70-98% has to become scattering surface. Accordingly, a configuration of the scattering surface, as shown  FIGS. 11(   c ),  12 ( c ) and  12 (D), left and right scattering lines  4  for scattering light properly left-rightward may be formed on the reflective surface c. 
         [0054]    In addition, as shown in  FIG. 13 , according to one embodiment of the present invention, the reflective surface c may formed within transparent material and the screen may be formed as roll screen to keep the inclined angle  3  of the reflective surface c and in this case the scattering lines  4  for scattering image light left-rightward may be formed on rear surface or front surface of the transparent material. Here, according to one embodiment of the present invention a polarizing angle of 3D image from the short focal point projector  2 , which is polarized and projected by a polarizing plate is kept on a surface of the reflective screen  1  and thus not only 2D image but also 3D image can be viewed. 
         [0055]    In a configuration of the present invention, a surface configuration of the reflective screen  1  is important and more detailed description including numerals is given below. 
       Example 1 
       [0056]    As shown in  FIG. 8 , the height h of the reflective screen  1  is 1240 mm which is derived from such that picture ratio of lateral length X height is 16:9 with respect to a typical HD TV and thus based on a diagonal of 2540 mm ( 100 ″) lateral length is 2210 mm and the height is 1240 mm. Accordingly, the height h of the reflective screen  1  equals to 1240 mm. Here, when the reflective screen  1  is arranged on about 5° above from the lower part of the reflective screen  1  in consideration of the height h of the short focal point projector  2 , the maximum height of the reflective screen  1  equals to 1300 mm, which is derived from 1240 mm plus 60 mm. Additionally, when the projection distance f of 100″ of the short focal point projector  2  is 500 mm, a projection range i which is projected on the reflective screen with the short focal point projector  2  equals to tan ∠=screen height h/projection distance of short focal point and thus the projection angle at the top end of the reflective screen  1  equals to 70° and the projection range i is 65° between 5° and 70°. 
         [0057]    Meanwhile, interval of the reflective surface c, as shown in  FIGS. 9(   a ),  10 ,  11 ( a ),  11 ( b ),  12 ( a ) and  12 ( b ), is defined from more than 0.1 mm to less than 30 mm. Here, when the interval of the reflective surface c is defined to less than 0.1 mm, the area of the reflective surface c is too small, decreasing reflection efficiency. However, when the interval of the reflective surface c is defined to more than 30 mm, reflection interval of the image becomes wider and thus respective different reflection angles may be formed therein, decreasing brightness uniformity of the reflective screen c. When the image is 2D image such as video image, the interval of the reflection surface c is defined to between 0.1 mm and 5 mm and further when the image is large one which is viewed from remote distance such as advertising image, the interval of the reflection surface c may be defined to between 5 mm and 30 mm wherein it may be add or deduct depending on picture size. 
         [0058]    According to one embodiment of the present invention, the interval of the reflective surface c is defined to 5 mm and hereinafter description thereof will be made based on the interval size 5 mm. 
         [0059]    When the interval size of the reflective surface c is 5 mm, the height of the reflective screen  1  is 1300 mm and thus line numbers of the reflective surface c equals to 260 from 1300 mm/5 mm. In addition, unit angel of the inclined angle  3  of the reflective surface c equals to 0.25° from 65°/260 lines. That is, a reflection angle b of the first line of the reflective surface c is 5°+0.25°=5.25°. Furthermore, the reflection angle b of the tenth line of the reflective surface c is 5°+(10×0.25°)=7.25° and the reflection angle b of the 260 th  line of the reflection surface c is 5°+(260×0.25°)≈70° However, the inclined angle  3  of the reflection surface c is a half of the reflection angle. That is, that is reason that when the reflection angle to incident angle is 90°, the inclined angle  3  of the reflection surface c becomes 45° based on normal line. Accordingly, as shown in  FIG. 10 , an arrangement angle of the reflection surface c of the first line is 5°=0.25°=5.25°×½=2.625° and the arrangement angle of the reflection surface c of 100 th  line is {5°+(100×0.25°)}×½=15° and further the inclined angle  3  of the 260 th  line of the reflective surface c is {5°+(260×0.25°)}×½=35°. 
         [0060]    That is, the inclined angle  3  of the reflective surface c, namely the arrangement angle ranges from 2.625° to 35° at from the first line to the 260 th  line wherein 0.125° is increased per a line in sequence depending on increasing line number of reflective surface c. Here, a shape of the reflective surface c, as shown in  FIG. 11(   a ), is formed as a circle wherein a central axis is eccentric axis  5  since the short focal point projector  2  is placed on a lower end of a screen and thus a center of the circle has to be placed on the lower end of the screen as eccentric axis for incident angle basis to be applied properly. 
         [0061]    In summary, according to one embodiment of the present invention, as shown in  FIG. 9(   a ), projector images multi incident to the reflective surface c at respective different projection angle a are divided into 260 lines each image having separately different incident angle of 0.25° and reflected straightly on the reflection surfaces c each having separately different inclined angle  3  of 0.125°, and all image are directed toward a viewer or a location D of a cubic glass. Here, the reflection surface c which is divided into 260 lines pursuant to a method as shown in  FIG. 9   a ), is transferred to a plain configuration as shown in  FIG. 9(   b ), thereby enabling to form thin film structure. In more detail, as shown in  FIG. 9 , the reflective surfaces c each having different reflective angles may form a reflective layer of a step structure such as saw teeth per the reflective surface c. Here, the reflective layer of the step structure as described above may interrupt the projected image from the short focal point lens, which is incident to at a high angel the reflective surface c, thereby making entire picture to be dark and uneven. Therefore, the reflective layer is transferred to a plain configuration as shown in  FIG. 9(   b ) with keeping the reflective angle, thereby forming a plain configuration of a thin film in which there is a reflective angle but there is no the reflective layer of the step structure. 
         [0062]      FIGS. 10 ,  11 ( b ), and  12 ( b ) show the same configuration as  FIG. 9(   b ). According to one embodiment of the present invention, the brightness on the reflective surface c which is divided into 260 lines is uniform and the hot spot phenomenon is eliminated due to left and right sides of the reflective surface are formed as a circle. Accordingly, high bright picture can be obtained. 
         [0063]    Meanwhile, as shown in  FIG. 9(   b ), length of the reflective surface c is enlarged and moved into a surface of a plain screen so that the height h of the reflective screen  1  can be enlarged, as shown in  FIG. 10 , and further technical advantages the same as spherical screen can be obtained through a thin film screen, not limiting to curvature r. 
         [0064]    In addition, all reflective screens  1  each having different sizes such as 80″ reflective screen  1  or 200″ reflective screen  1  may be applied to the aforementioned principles. Besides, when the short focal point projector  2  is placed on the upper end of the reflective screen  1 , the aforementioned principle may be applied adversely. 
       Example 2 
       [0065]    When the line of the reflective surface c is configured in the manners as described above such that as shown in  FIG. 12 , the lines are arranged left-rightward horizontally, hot spot appearance may occur left-rightward. However, when reflection rate of the reflective screen  1  is defined to 2-8 gains of comparatively low level, left-right scattering lines  4  may be formed on a surface of the reflective screen  1 , as shown in  FIG. 12(   a ), or curved lines of a lenticular form may be formed up-downward for the image to be diffused left-rightward so that left-right hot spot appearance can be avoided. In this case, of course, the configuration of the reflective surface c is configured such that the inclined angles  3  of the reflective surface c depending on the incident angles a are accumulated from separate different lines which are made by dividing the reflective surface. According to the present invention, the projected images are reflected themselves through refraction and reflection of the reflective surface c formed on a surface of the reflective screen  1  and thus clear image may be obtained when cubic image is displayed through polarized projection. 
       Example 3 
       [0066]    The aforementioned structure may be formed as thin film type such as the reflective screen  1 , as shown in  FIG. 13 . That is, the interval of the reflective surface c is defined to 0.1-30 mm. Furthermore, arrangement inclined angle  3  is defined to less than 1-45° and thus the thickness of the reflective screen  1  may be formed of 0.1-30 mm as thin film. That is, thickness per unit of the reflective surface c may be formed as thin film S, as shown in  FIG. 9(   b ), comparing to the thickness T of the prior spherical screen, as shown in  FIG. 9(   a ). In other words, when a projector having a short focal point distance of 50 cm is used, the thickness T of the spherical screen becomes 1 m, as shown in  FIGS. 5 and 9(   a ). 
         [0067]    According to one embodiment of the present invention, the thickness T of the spherical screen of the reflective screen is divided into 0.1-30 mm of the interval of the reflective surface and the reflective surface is transferred to a plain screen configuration, as shown in  FIGS. 9  ( a ) and  10 , and thus the thickness of the thin film configuration S may also be formed as of 0.1-30 mm. 
         [0068]    Additionally, as shown in  FIG. 13 , a surface of the reflective screen  1  may be made of transparent material X and a rear surface thereof is made of protective film and the reflective surface c is made therebetween. At this time, the transparent material X has to have refraction rate within 1.5 as the same as the reflective surface c so that polarity degree of 3D image is to be kept. Meanwhile, even when the screen according to the present invention is formed as a roll screen, the inclined angle  3  is to be kept. 
         [0069]    Accordingly, the reflective screen  1  may be made from flexible material such as film or plastic resin for easy installment and transportation to form roll screen. Additionally, the reflective screen according to the present invention may be combined with a short focal point projector as shown in  FIG. 8 , and thus the screen and the projector may be formed integrally, and further a large screen may be formed without hot spot phenomenon, regardless of short projection distance of the short focal point projector. Finally, when 2D or 3D image is selected and projected by a 3D projector, 2D or 3D image can be selected and viewed on one screen, and further high bright 2D or 3D image of 2-30 gains can be viewed through one thin film screen and thus it may be applied to a home theater for 2D and 3D, a screen game unit for 2D and 3D and advertizing unit, etc. 
         [0070]    While embodiments of the invention are described referring to the preferred embodiments, the invention is not limited thereto, and thus various variation and modification can be made without departing from a scope of the invention.