Abstract:
A cover of a head up display and a housing including the head up display cover are provided. The cover of a head up display includes a cover member and a cover panel that is coupled with a lower portion of the cover member and has an elliptical reflecting curved surface that reflects external incident light. The cover and the housing allow the viewing region of a driver to be enlarged while satisfying reflection conditions which reflect external incident light under the elliptical cross-section of a driver&#39;s eye.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2013-0041483 filed in the Korean Intellectual Property Office on Apr. 16, 2013, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a cover of a head up display and a housing that includes the cover. More particularly, the present invention relates to a cover of a head up display with an elliptic reflective surface and a housing that includes the cover. 
         [0004]    (b) Description of the Related Art 
         [0005]    In general, a head up display (HUD) has been developed to provide flight information to an airplane pilot and the HUD is mounted on an aircraft, particularly, a fighter. Recently, the HUD has been applied to a vehicle to conveniently report running information of the vehicle to a driver for the vehicle. 
         [0006]    The HUD applied to the vehicle outputs various information such as running information or navigation information of the vehicle necessary to operate the vehicle and is mounted on a front glass window of the vehicle within a range without departing from a main visual field of a driver while the driver runs the vehicle. 
         [0007]    The HUD for a vehicle as described above includes a liquid crystal panel installed an inner side of an instrument panel in front of a driver side to display a running information image, a light emitting unit or a backlight unit that illuminates the liquid crystal panel, an optical system that enlarges or reduces the running information image displayed on the liquid crystal panel to a suitable size and adjusts a focus of the image, and a reflecting mirror that reflects the running information image adjusted by the optical system on a front glass window of the vehicle to display the running information image on the front glass window of the vehicle. 
         [0008]    The liquid crystal panel, the light emitting unit, the optical system, and the reflecting mirror are embedded and mounted within a housing that has a box shape. An opening that has a predetermined size is formed in the housing to allow image light reflected through the reflecting mirror to be irradiated to the front glass window of the vehicle. A dust cover or a cover is mounted in the opening to prevent a foreign material such as dust from flowing into the housing through the opening. 
         [0009]    In the foregoing HUD for a vehicle, to enlarge a viewing region of the driver, the size of the opening must be increased. Due to limitation of a mounting space for the HUD and interference between peripheral components, the sizes of housing and the opening thereof may not be increased to a predetermined size or greater. 
         [0010]    The above information disclosed in this section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0011]    The present invention provides a cover of a HUD and a housing that includes the same having advantages of enlarging a viewing region of a driver by increasing a size of an opening into which an image light is irradiated in a housing that has a limited mounting space and a limited size satisfies a reflecting condition of an external incident light such as sunlight. 
         [0012]    According to an exemplary embodiment of the present invention, a cover of a head up display may include: a cover member; and a cover panel coupled with a lower portion of the cover member and having an elliptical reflecting curved surface that reflects external incident light. A first focus may be formed at one edge of the cover member; and the elliptical reflecting curved surface may be formed based on the first focus. 
         [0013]    When a first external incident light passes through the first focus may be firstly reflected to a wind shield by the elliptical reflecting curved surface and may then be secondarily reflected toward the driver by the wind shield, a curvature of the elliptical reflecting curved surface may be set to cause the light to be reflected to a lower location by a predetermined interval than the elliptical shape (e.g., cross section) of an eye of the driver. 
         [0014]    The elliptical reflecting curved surface may be formed allowing a second focus to be disposed above the first focus; and the elliptical reflecting curved surface may be formed allowing the second incident light incident to the elliptical reflecting curved surface between the first focus and the second focus to pass through a lower region of the elliptical cross-section of an eye. A curvature of the elliptical reflecting curved surface and the cover member may be formed allowing a third incident light incident to the elliptical reflecting curved surface from an upper region of the second focus to be primarily reflected toward the cover member by the elliptical reflecting curved surface, and may be blocked by the cover member to achieve secondary reflection. 
         [0015]    According to another exemplary embodiment of the present invention, a housing of a head up display may include: the cover; and a housing body that has a hollow box shape and in which an opening may be formed, the cover being mounted in the opening. The cover may be disposed in the opening in which an image light source is irradiated to efficiently prevent foreign materials from entering the housing. 
         [0016]    Further, since the cover has an elliptical reflecting curved surface, external incident light such as sunlight may be reflected by the cover and may then be condensed at one focus at a lower location than the elliptical cross-section of an eye of the driver, not to prevent a front visual field of the driver. In addition, since the cover has the elliptical reflecting curved surface, the size of the opening in the housing having a limited size may be increased, so that a viewing region of the driver may be optimally enlarged. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is an exemplary view illustrating a housing of a HUD according to an exemplary embodiment of the present invention; 
           [0018]      FIG. 2  is an exemplary cross-sectional view taken long line A-A of  FIG. 1  according to an exemplary embodiment of the present invention; 
           [0019]      FIG. 3  is an exemplary view illustrating a method of drawing an ellipse of a cover according to an exemplary embodiment of the present invention; and 
           [0020]      FIGS. 4 and 5  are exemplary views illustrating reflection of external light of a cover of a HUD according to an exemplary embodiment of the present invention, 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, combustion, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g, fuels derived from resources other than petroleum). 
         [0022]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items, 
         [0023]    Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about.” 
         [0024]    Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
         [0025]    Referring to  FIG. 1 , the housing  10  of a HUD according to an exemplary embodiment of the present invention may include a housing body  12  that has an approximate box shape. The housing  10  may have a hollow box shape. Although not shown in an inside of the housing  10 , a liquid crystal panel that displays a running information image (e.g., a vehicle operation image), a light emitting unit or a backlight unit that illuminates the liquid crystal panel, an optical system that increases or reduces the running information image displayed on the liquid crystal panel to a suitable size and adjusts a focus of the image, undo reflecting mirror that reflects the running information image adjusted by the optical system on a front glass window of the vehicle to cause the running information image to be displayed on the front glass window of the vehicle may be embedded within the housing  10 . 
         [0026]    In addition, an opening may be formed at an upper portion of the housing body  12  and connect an interior of the housing with an exterior of the housing, and a dust cover or a cover  20  may cover the opening to prevent a foreign material such as dust from flowing into the housing  10 . The cover  20  may be made of a transparent acryl material allowing image light may be displayed to the exterior of the housing  10  through the reflecting mirror. Referring to  FIG. 2  showing a section of the housing  10 , a reflecting mirror  14  that reflects the image light may be embedded inside the housing  10 . The cover  20  may include a cover panel  22  that slowly protrudes toward an interior of the housing  10 , and a cover member  24  may include a lower portion coupled with the cover panel and may be disposed along an edge of the opening. In addition, an outer side of the cover panel  22  may have an elliptical reflecting curved surface  22   a.    
         [0027]    When external incident light  30  such as sunlight is incident to the elliptical reflecting curved surface  22   a , the light  30  may be primarily reflected toward a wind shield  40  by the elliptical reflecting curved surface  22   a , and may then be condensed at one focus at a lower location than the elliptical cross-section  50  of an eye of the driver, to not obstruct a front visual field of the driver. The elliptical reflecting curved surface  22   a  has an elliptical shape that is non-circular. In particular, a curvature of the elliptical reflecting curved surface  22   a  may be set to allow the condensed focus to be formed at the lower location of about 20 mm with respect to elliptical cross-section  50  of the driver eye, thereby satisfying reflecting condition of the cover  20 . 
         [0028]    Referring to  FIG. 3 , the elliptical reflecting curved surface  22   a  may be a part of an ellipse having a first focus F 1  and a second focus F 2 . The first focus F 1  may be disposed at an edge of the cover member  24  above one front end of the elliptical reflecting curved surface  22   a.    
         [0029]    The first external incident light  32  approximately horizontally incident to the first focus F 1  may form the first reflecting light  32   a  toward the wind shield  40  by the elliptical reflecting curved surface  22   a , and the first reflecting light may form the second reflecting light  32   b  reflected toward the driver by the wind shield  40 , a curvature of the elliptical reflecting curved surface  22   a  may be set to allow the second reflecting light  32   b  to be disposed at a lower location of minimum about 20 mm than the elliptical cross-section  50  of the driver eye. 
         [0030]    Accordingly, when the elliptical reflecting curved surface  22   a  is formed, since the housing  10  that has a limited size may increase the size of the opening, for example, a width W of the opening, a size of an image output to the wind shield  40  through the opening to optimally enlarge a viewing region of the driver. 
         [0031]    Referring to  FIG. 4 , since the second external incident light  34  incident into the elliptical reflecting curved surface  22   a  of the cover  20  from a space between the first focus F 1  and the second focus F 2  may form the third reflecting light  34   a  reflected toward the wind shield  40  by the elliptical reflecting curved surface  22   a , the third reflecting light  34   a  may form the fourth reflecting light  34   b  again reflected toward the driver by the wind shield  40 , the fourth reflecting light  34   b  may be disposed below the second reflecting light  32   b  to not obstruct a front visual field of the driver, thereby satisfying reflecting conditions. 
         [0032]    Referring to  FIG. 5 , the third external incident light  36  introduced into the elliptical reflecting curved surface  22  of the cover  20  in an upper region of the second focus F 2  may be blocked by the cover member  24  under the first focus F 1  to not form secondary reflection, to allow reflecting conditions to be satisfied. 
         [0033]    As mentioned above, an exemplary embodiment of the present invention is disclosed herein, but the present invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the appended claims and the detailed description and the accompanying drawing of the present invention. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
             
               
               
               
             
           
               
                   
               
               
                 Description of symbols 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10: housing 
                 12: housing body 
               
               
                   
                 14: reflecting mirror 
                 20: cover 
               
               
                   
                 22: cover panel 
                 22a: elliptic reflecting curved surface 
               
               
                   
                 24: cover member 
                 30, 32, 34, 36: incident light 
               
             
          
           
               
                   
                 32a, 32b, 34a, 34b, 36a, 36b: reflecting light 
               
             
          
           
               
                   
                 40: wind shield 
                 50: elliptical cross-section