Abstract:
A vehicle includes a heads up display module emitting polarized light. A windshield reflects the polarized light toward a driver of the vehicle. A lens clips onto polarizing eyeglasses worn by the driver. The lens includes a waveplate.

Description:
FIELD OF THE INVENTION 
       [0001]    The disclosure relates to the field of eye glasses, and, more particularly, to a pair of lenses that may be clipped-on a pair of eye glasses. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is known for heads-up displays (HUDs) to be provided in association with a vehicle&#39;s front windshield. Conventional HUDs use reflection from the inner and outer surfaces of the windshield to create an image that, as seen by the driver, is composed of almost completely polarized light. It is common for drivers to wear polarizing sunglasses. The sunglasses are designed with polarizers oriented to block glare from water on the road. Unfortunately, this also blocks the HUD image that reflects from the windshield. The current practice is to advise the driver not to use polarizing sunglasses with a HUD, or to make do with the small fraction of light from the HUD that is passed by the sunglasses. 
       SUMMARY 
       [0003]    The present invention may provide a pair of lenses each of which clips over a respective one of the two lenses of polarizing sunglasses to enable a driver wearing the sunglasses to more easily see the image from a conventional heads up display (HUD). Each inventive lens may contain a waveplate which may be fastened over the respective polarizing lens of the sunglasses to increase the amount of light from the HUD that the driver sees. 
         [0004]    In one embodiment, the invention comprises a vehicle including a heads up display module emitting polarized light. A windshield reflects the polarized light toward a driver of the vehicle. A lens clips onto polarizing eyeglasses worn by the driver. The lens includes a waveplate. 
         [0005]    In another embodiment, the invention comprises an automotive display method, including providing a vehicle with a heads up display. Polarized light is emitted from the heads up display. The polarized light is reflected off of a windshield and toward a driver of the vehicle. The driver is provided with a lens configured to clip onto polarizing eyeglasses worn by the driver. The lens includes a waveplate. 
         [0006]    In yet another embodiment, the invention includes a vehicle having a heads up display module emitting polarized light. A windshield reflects the polarized light toward a driver of the vehicle. A lens is attached to polarizing eyeglasses worn by the driver. The lens includes a waveplate having an axis that is oriented at an angle of approximately between 35 degrees and 55 degrees relative to a vertical direction. 
         [0007]    The invention may have the advantage that the driver may better see the display produced by a HUD. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings. 
           [0009]      FIG. 1 a    is a side schematic view of one embodiment of a HUD image enhancement lens arrangement of the present invention. 
           [0010]      FIG. 1 b    is a schematic plan view of the clip-on lens of the arrangement of  FIG. 1   a.    
           [0011]      FIG. 2  is a flow chart of one embodiment of an automotive display method of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]      FIG. 1 a    illustrates one embodiment of a HUD image enhancement lens arrangement  10  of the present invention, including a HUD optics module  12 , a windshield  14 , a clip-on lens  16 , and polarizing eyeglasses  18  worn on a driver&#39;s head  20 . There may be two clip-on lenses  16 , a respective one for each of two polarizing lenses of eyeglasses  18 . 
         [0013]    During use, polarized light  22  from HUD optics module  12  is incident to the driver  20 , the polarized sunglasses  18 , and the clip-on lens  16 . Lens  16  contains a waveplate and is clipped over the sunglasses  18 . The waveplate may alter the polarization state of the polarized light  22  travelling through the waveplate. The waveplate may be a half-wave plate, which shifts the polarization direction of linearly polarized light, or a quarter-wave plate, which converts linearly polarized light into circularly polarized light and vice versa. A quarter wave plate can be used to produce elliptical polarization as well. 
         [0014]    As shown in  FIG. 1   b,  an axis  24  of the waveplate may be oriented at an angle θ of approximately 45 degrees from a vertical direction  26 . If the waveplate is a half-wave plate, oriented as shown by axis  24 , then the waveplate may change incident linearly polarized light to polarized light with the direction of polarization rotated by 90 degrees. Consequently, instead of the polarizing sunglasses almost completely blocking the light from the HUD and passing the light from the outside scene as in the prior art, the inventive lens  16  causes light from the HUD to be preferentially passed to the driver relative to the light from the outside scene. 
         [0015]    If the waveplate is a quarter-wave plate, oriented as shown by axis  24 , then the waveplate may change the incident polarized light into circularly polarized light. Consequently, the polarizing sunglasses may attenuate the light from the outside scene and the light  22  from the HUD to an approximately equal degree, rather than blocking the HUD light more than the outside light, as in the prior art. 
         [0016]    If the waveplate is not one of these two special cases of a half-wave plate or a quarter-wave plate, or is not oriented at exactly 45 degrees from the vertical direction, the waveplate may still provide approximately the same functionality. 
         [0017]      FIG. 2  illustrates one embodiment of an automotive display method  200  of the present invention. In a first step  202 , a vehicle is provided with a head up display. For example, a head up display may be installed in the dashboard for projecting a light field onto the windshield. In a next step  204 , polarized light is emitted from the head up display. That is, the light field projected from the head up display may include polarized light. Next, in step  206 , the polarized light is reflected off of a windshield and toward a driver of the vehicle. For example, the head up display may direct the polarized light in a direction such that the light is reflected off of the windshield and impinges upon the eyes of the driver of the vehicle. In a final step  208 , the driver is provided with a lens configured to clip onto polarizing eyeglasses worn by the driver, the lens including a waveplate. For example, clip-on lenses  16  may be clipped onto polarizing eyeglasses  18  worn by driver&#39;s head  20 , wherein lenses  16  each include a waveplate. 
         [0018]    The foregoing description may refer to “motor vehicle”, “automobile”, “automotive”, or similar expressions. It is to be understood that these terms are not intended to limit the invention to any particular type of transportation vehicle. Rather, the invention may be applied to any type of transportation vehicle whether traveling by air, water, or ground, such as airplanes, boats, etc. 
         [0019]    The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications can be made by those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention.