Patent Publication Number: US-2021173177-A1

Title: Magnetic mirror movement

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Application No. 62/943,849 filed on Dec. 5, 2019, the disclosure of which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a system for moving a mirror in a head up display of a motor vehicle. 
     2. Description of the Related Art 
     A head up display emits light that reflects from the front windshield to be seen by the driver. The light appears to come from a virtual image in front of the driver and in front of the windshield. This type of head up display is currently commercially available. 
     Conventional head up displays create the virtual image by first using a display to create an image. Next, the light from the image is reflected from one or more mirrors. Next, the light from the mirrors is directed up to the windshield and is then reflected from the windshield towards the driver. The mirrors are designed and positioned relative to the display so that the light seen by the driver, which is reflected from the windshield, appears to come from a virtual image that is outside of the vehicle. The mirrors and display are typically contained in a package that occupies a volume beneath the top surface of the dashboard. 
     Currently, all head up displays include a stepper motor as the movement mechanism, and there are no alternate ways of moving the mirrors inside of head up displays. 
     SUMMARY OF THE INVENTION 
     The invention may be a replacement for current mirror movement mechanisms in head up displays or other applications using a stepper motor. By use of electromagnets wired in such a way that each can be controlled individually, the position of the movable mirror inside of a head up display may be controlled. 
     The invention may reduce the size of a head up display (HUD). The inventive mirror movement mechanism may enable a reduction in the horizontal size of the HUD and enable the head up display to fit into many more vehicles that have tight packaging restrictions. 
     In addition to size reduction, the inventive method may enable completely quiet operation and may reduce all audible noise created by stepper motor operation. To the end user/driver of the vehicle, the mirror movement may be completely silent. 
     The invention comprises, in one form thereof, a mirror arrangement including a mirror that is rotatable about an axis. A mirror magnet is attached to the mirror. A plurality of electro-magnets are positioned relative to the mirror magnet such that the electro-magnets can be individually activated to thereby attract or repel the mirror magnet and thereby cause rotation of the mirror about the axis. 
     The invention comprises, in another form thereof, a method for positioning a mirror of a head up display in a motor vehicle. The method includes attaching a mirror magnet to the mirror. A plurality of electro-magnets are positioned in association with the mirror magnet. At least one of the electro-magnets is individually activated to thereby attract or repel the mirror magnet and thereby cause rotation of the mirror about an axis. 
     The invention comprises, in yet another form thereof, a mirror arrangement including a mirror that is rotatable about an axis. A mirror magnet is attached to the mirror. A plurality of electro-magnets are positioned in an arcuate pattern such that the electro-magnets can be individually activated to thereby attract or repel the mirror magnet and thereby cause rotation of the mirror about the axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a schematic perspective view of a magnetic tab and mirror of one embodiment of a mirror arrangement of the present invention. 
         FIG. 2  is a schematic side view of the mirror arrangement of  FIG. 1  along line  2 - 2  of  FIG. 1 . 
         FIG. 3  is a flow chart of one embodiment of a method of the present invention for positioning a mirror of a head up display in a motor vehicle. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments hereinafter disclosed are not intended to be exhaustive or limit the invention to the precise forms disclosed in the following description. Rather the embodiments are chosen and described so that others skilled in the art may utilize its teachings. 
       FIG. 1  illustrates one embodiment of a mirror arrangement  10  of the present invention including an aspheric mirror  12  having a magnetic tab  14  attached thereto. Aspheric mirror  12  may be a movable mirror inside of the HUD unit. Magnetic tab  14  may house a mirror magnet  16 . Magnetic tab  14  can be a separate component from mirror  12 . Alternatively, magnetic tab  14  can be molded from the same tool as mirror  12 , with magnet  16  being later inserted into tab  14 . Mirror  12  may be rotatable about an axis  17 . 
     A magnet chain  18  ( FIG. 2 ) includes many electro-magnets  20   a - g  in close proximity to magnetic tab  14 . Electro-magnets  20   a - g  may be arranged concentricly about axis  17 . 
     Each of electro-magnets  20   a - g  is capable of attracting magnetic tab  14  when the electro-magnet is electrically activated or energized so as to be magnetic. Each electro-magnet  20   a - g  in magnet chain  18  can be controlled and activated individually to attract magnetic tab  14  closer to the activated one of electro-magnets  20   a - g.  By precisely controlling which of electro-magnets  20   a - g  is activated, the position of magnetic tab  14  may be reliably and accurately adjusted either in the direction of arrow  22   a  or in the direction of arrow  22   b,  which in turn moves the entire aspheric mirror  12  about axis  17 . 
     Magnet chain  18  may be a molded piece of plastic which houses many electro-magnets. The magnet chain molding may follow the curvature of the movement of the mirror, so magnet chain  18   a  may define a radius having axis  17  at, and coincident with, the origin or end of the radius. Thus, the length of the radius depends on various factors of the optical design (e.g., mirror position, mirror size, axis of rotation). 
       FIG. 3  illustrates one embodiment of a method  300  of the present invention for positioning a mirror of a head up display in a motor vehicle. In a first step  302 , a mirror magnet is attached to a mirror. For example, mirror magnet  16  may be attached to mirror  12  through magnetic tab  14 . 
     In a next step  304 , a plurality of electro-magnets are positioned in association with the mirror magnet. For example, chain  18  of electro-magnets  20   a - g  may be placed close enough to magnet  16  that electro-magnets  20   a - g  may attract and/or repel magnet  16 . Chain  18  may be shaped to be concentric about mirror axis of rotation  17 . However, it is also possible for chain  18  to be linearly-shaped or to have many other possible shapes so long as each of electro-magnets  20   a - g  is disposed at a different respective distance and/or direction from magnet  16 . 
     In a final step  306 , at least one of the electro-magnets is individually activated to thereby attract or repel the mirror magnet and thereby cause rotation of the mirror about an axis. For example, in the positions shown in  FIG. 2 , electro-magnet  20   a  may be activated to attract magnet  16  and thereby cause rotation of mirror  12  in direction  22   a  about axis  17 . 
     While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.