Abstract:
An apparatus for producing aerial images is disclosed employing a combination of plastic spherical mirrors, beamsplitter polarizing filters, and light sources. An object to be displayed is illuminated, and its image is partially reflected by the beamsplitter to a focusing mirror and reflected to an aerial position. A polarizer prevents ambient lights or images from degrading or interfering with the aerial images. A clock radio, a personal television display counter, as well as animated mannequin versions are disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority benefit of U.S. Provisional Application Ser. No. 60/839,740, filed on Aug. 23, 2006. All disclosure of the U.S. provisional application is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an aerial-image display system. More particularly, the present invention relates to an optimized aerial-image display system having a low-cost spherical mirror applied to consumers&#39; displays. 
   2. Description of Related Art 
   Aerial-image displays in which an image of an object appears in space are intriguing whenever seen. Examples of aerial images may be found in the following environments: Example 1: theme parks having a haunted mansion with dancing skeletons; Example 2: magical stage acts with apparent floating heads; Example 3: motion picture illusions depicting ghostly figures. 
   Typically, these images are beyond reach of the observer and recognized to be an illusion and transitory so as not to be carefully examined by the observer. Such images have seldom been produced with such precision and detail that they convince the observer that they are the actual objects displayed. Likewise, these images, if ever, are seldom displayed within reach of the observer who can try to touch them only to be surprised upon realizing that the three-dimensional image hangs in mid air. Likewise, it is not possible to one&#39;s knowledge to produce an aerial image of an object in which the observer, standing in one position, is able to see the object rotate before his eyes and examine it in detail without having the actual object in reach. 
   Examples of aerial systems are disclosed in the following patents: U.S. Pat. No. 5,944,403 D. Krause Aug. 31, 1999 U.S. Pat. No. 4,348,187 M. Dotsko Sep. 7, 1982 
   In the case of displaying retail merchandise, a perennial problem typically in the jewelry trade is to allow a prospective customer to visually examine the merchandise, such as jewelry, from all sides without touching the jewelry. Keep in mind that in the sales effort, touching the jewelry has heretofore been necessary in most cases. 
   Employing an aerial image of fine jewelry can eliminate the need to touch the jewelry by casual shoppers and also provides for security of the actual jewelry, while allowing the casual observer and potential customer to view it as completely as if they had the jewelry in their hands. 
   Likewise in the jewelry field, most retailers must remove fine jewelry from their display cases or windows at night and thereby forego the opportunity to display the fine jewelry through a show window or showcase while the jewelry is in a secure or remote location. 
   In the entertainment field, the aerial image display can be used to provide a totally real image of a natural object in space, within reach of an observer, again without contact by the observer. The effect of the image appearing to be the actual object, but without the tactile feel when attempted to be touched, is a marvelous attention getter. 
   At trade shows, objects can be displayed and rapidly changed at the same location and the viewer sees the aerial image and not the actual object in close proximity as would be the case if the actual object were on display. 
   In the field of video games, a reasonably high degree of reality can be portrayed on a video screen, but by the very nature of the screen&#39;s presence, the player is intensely aware that the entire scene is on a video screen. Attempts have been made to enhance or disguise directly viewed video displays (usually CRTs) with unexciting results. 
   In the field of transportation, particularly aircraft and automobiles, the use of “heads up” displays are becoming popular. They involve complex optics, which display the instruments on the canopy of aircraft or windshields of automobiles. In accordance with this invention, such aerial images may be displayed between the eyes of the pilot or driver and the canopy or windshield. 
   These are just a few examples of the application of this invention and are by no means all of the applications to which this invention may be applied. 
   In any situation where an accurate display of an object for a number of observers is needed, the aerial-image display of this invention is applicable. Other examples include various levels of education from elementary through graduate schools. In scientific and medical institutions, aerial-image displays, in accordance with this invention, may be an ideal teaching tool to present details to a number of students simultaneously with any of them being able to point to an area of the aerial image corresponding to the area of the object displayed in full view of the other observers. 
   In accordance with this invention, the optics is extremely precise when producing real images but not so complex that the aerial-image display of this invention may not be incorporated in day-to-day objects around the home, primarily for personal use. An example is a bedroom clock, which displays the clock face in nearby space but without any interference with the observer should he enter the image space. 
   On the other hand, glass has been the conventional material of choice for use as a spherical mirror. One of the most important reasons is because plastics technologies were not as developed as they are today. In other words, the tools and materials were not available as they are today. Metal mold tolerances and the resulting parts can be specified and held in the tens of thousandths of an inch. Materials used today are more sophisticated; the plastics are able to emulate the thermal stability and durability similar to that of glass, and to endure the type of operating conditions in the past that only glass could have tolerated. 
   Glass spherical mirrors are expensive because of the secondary operations needed to prepare the mirror surface after it is heat formed or slumped to shape. These secondary operations include annealing, grinding and polishing. The annealing process is used to strengthen the glass so that it is strong enough to undergo the grinding and polishing operation, as well as adding the additional strength needed to resist breakage during usage. The grinding and polishing stages are necessary because of the limits of the tolerance capabilities of glass forming molds and the physical nature of glass. 
   Unfortunately, the grinding and polishing stages require a considerable amount of manual processing for producing a finished product; therefore, they are often considered semi-automated processes. 
   In addition, glass also has the serious drawbacks of breakage, weight, and expensive shipping costs. To endeavor to overcome the limitations and drawbacks of glass, a low-cost glass forming was developed. However, the low-cost glass forming did not provide an acceptable surface finish, and the resulting cost reductions were not comparable to that of plastic. Clearly, what is needed is a method and system for manufacturing a plastic parts to reduce the weight of a spherical mirror to approximately one-third that of glass, and for making a low-cost plastic spherical mirror of comparable performance to glass spherical mirror. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to an aerial-image display system with a plastic mirror. The optics of the system is extremely precise when producing real images but not so complex that the aerial-image display of this invention may not be incorporated in day-to-day objects around the home, primarily for personal use. An example is a bedroom clock, which displays the clock face in nearby space but without any interference with the observer should he enter the image space. 
   The present invention is further directed to an aerial-image display system with a plastic mirror. A method and a system for manufacturing a low-cost plastic spherical mirror of comparable performance as that of a glass spherical mirror are applied to the system. According to the present invention, a plastic injection molding method is used for manufacturing a plastic parts of a low-cost plastic spherical mirror. The plastic injection molding method is able to yield higher tolerance, improved process control, and higher repeatability. 
   In an embodiment of the present invention, the plastic injection molding method is used for manufacturing the plastic parts of the low-cost plastic spherical mirror. The plastic injection molding method is able to yield higher tolerance, improved process control, and higher repeatability. 
   A metal mold used for the injection molding method is able to hold a tight tolerance for a general envelope dimension for a mirror (not the mirror surface). The spherical radius tolerance is also able to be held at the tight tolerance. The aforementioned tolerances are comparable to that of a glass spherical mirror. The metal mold used for the injection molding method may be able to be held at the tight tolerance. 
   A plurality of plastic material formulations has been developed in which a plurality of performance criteria relating to material strength, thermal stability, water absorption, mold shrinkage, material flow into the mold, UL recognition, manufacturing considerations, surface density, lubricant content, and scratch resistance are satisfied. The selection of the plastic material formulation may be based on the metal mold and part testing results. 
   Vacuum metallization or vacuum deposition may be used for depositing a reflective mirror coating serving as the mirror surface of the spherical mirror. The metal deposited on the plastic surface is preferably at a thickness of several microns. A metallization phase is performed following by a protective overcoat being sprayed on the metalized surface. The metalized parts undergoing the vacuum metallization then has a sufficient quality because of improved quality control of the surface of the plastic material that is being coated by means of the ability to minimize the amounts of flaws on the plastic surface resulting from the molding process. 
   The method according to an embodiment of the present invention for producing the plastic parts of the plastic spherical mirror includes the following steps: 
   a) designing a plastic parts, such that a mirror surface is supported to avoid aberration or distortion; 
   b) accurately positioning plastic injection gates, so as to ensure the elimination of remnants or knit lines created by plastic resin flow; 
   c) selecting a preferred physical size of the plastic parts, so as to meet a plurality of optical performance requirements and physical design requirements; 
   d) forming a plurality of support walls at strategical positions in the plastic part; 
   e) selecting the plastic material formulation, so as to be specially designed to resist deformation; 
   f) fabricating tools with a preferred grade of steel having a preferred polished surface; 
   g) heating and/or cooling the metal mold to form an optimal curvature on the mirror surface; 
   h) depositing a thin layer of a reflective metal coating onto the mirror surface of the plastic parts; and 
   i) forming a protective overcoat on the metallized mirror surface. 
   A plastic spherical mirror fabricated through conducting the aforesaid method includes a plastic parts with a preferred size and a mirror surface supported by a plurality of wall structures, a plastic material formulation, a superior optical grade finish formed by polishing the mirror surface of a metal mold, an optimal curvature on the mirror surface formed by heating and chilling the metal mold so as to form the optimal curvature on the mirror surface, a thin layer of a reflective metal coating deposited onto the mirror surface of the plastic parts, and a protective overcoat formed on the metalized mirror surface. 
   In addition, according to a second embodiment, the plastic spherical mirror further includes a plurality of strategically-placed injection gates and the plastic parts having the preferred physical size. Moreover, a plurality of support walls is placed in the plastic parts, such that a final design dimension of the plastic parts matches that of a glass counterpart. 
   In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, several embodiments accompanied with figures are described in detail below. 
   It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIG. 1  is an isometric view of an aerial-display device in accordance with this invention in the form similar to the popular video game housings. 
       FIG. 2  is a rear three-quarter partly exploded isometric view of the housing of  FIG. 1 . 
       FIG. 3  is a vertical sectional view through the housing of  FIG. 1  showing the relative positions of the optical elements of the invention when the source of the image to be displayed is a video screen showing the field rays defining the full field in dotted lines and the image rays in dashed lines. 
       FIG. 4  is a vertical sectional view of the embodiment of  FIG. 1  designed to produce aerial images of a physical object in either a fixed position or rotatable on a turntable. 
       FIG. 5  is a vertical sectional detail of the partially silvered beamsplitter and circular polarizer of this invention shown attached to their respective mounting boards. 
       FIG. 6  is an isometric view of the concave mirror mounting board and mirror. 
       FIG. 7  is a detailed view in section of the mounting arrangement for the concave mirror on its supporting board. 
       FIG. 8  is a front elevational view of the object turntable of  FIG. 4 . 
       FIG. 9  is a sectional view through a portion of the concave mirror used in this invention. 
       FIG. 10  is a front elevational view of the display device of  FIG. 4  with the lower front housing partly broken away to illustrate the position of the internal lamps relative to the turntable and object to be displayed. 
       FIG. 11  is an isometric view of an alternative embodiment of this invention designed for aerial display without an image shelf. 
       FIG. 12  is an isometric view of a tabletop clock radio incorporating this invention. 
       FIG. 13  is a vertical sectional view through a clock radio of  FIG. 12 . 
       FIG. 14  is an isometric view of a tabletop TV, which includes an aerial image of the TV screen display utilizing this invention. 
       FIG. 15  is a vertical sectional view through the tabletop TV of  FIG. 14 . 
       FIG. 16  is a vertical sectional view through the housing of  FIG. 1  showing a downward-facing concave mirror as a part of another embodiment. 
       FIG. 17  is a vertical sectional drawing through the housing of  FIG. 1  showing two concave mirrors for improved brightness of this invention. 
       FIG. 18  is a vertical sectional view through a video display in which a video camera is incorporated to photograph small objects. 
       FIG. 19  is a vertical sectional view through a display showing a talking head projecting an image from a VCR or streaming media from, as an example, dedicated web site on the internet. 
       FIG. 20  is an alternate mirror configuration where the concave mirror is a flexible, metallized film mirror. 
       FIG. 21  is an alternate mirror configuration using a molded plastic concave mirror. 
       FIG. 22  shows a glass-topped display case or housing for use in retail stores. 
       FIG. 23  is an isometric (perspective) view of the glass-topped display case of  FIG. 22 . 
       FIG. 24  illustrates an embodiment of a method in accordance with the present invention for fabricating a plastic spherical mirror. 
       FIG. 25  illustrates an embodiment of a trimmed plastic parts for use for a plastic spherical mirror in accordance with the present invention. 
       FIG. 26  illustrates another embodiment of a method in accordance with the present invention for fabricating a plastic spherical mirror. and 
       FIG. 27  illustrates another embodiment of a plastic parts directly after injection molding in accordance with the present invention 
   

   DESCRIPTION OF EMBODIMENTS 
   The present invention will now be described with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. 
   For the sake of convenience of understanding, some key terms and phrases are presented first. 
   A “plastic material formulation” may comprise homopolymer, thermoplastic, copolymer, polymer blend, thermosetting resin, polymer blend, any one of the above materials containing performance additives, fillers, or fibers, or any other similar types of polymer material formulations. 
   A “depositing of a reflective metal coating onto the mirror surface of the plastic parts” may be accomplished by vacuum deposition, spin coating, spraying, vacuum metallization, sputtering, or any other similar system capable of depositing the reflective metal coating on the order of several microns. 
   “Low-cost” may be defined as a favorable cost differential as compared to glass of the same dimensional configuration serving as the spherical mirror. 
   A “glass counterpart” is defined as a glass spherical mirror of the same dimensional configuration and possesses equivalent functionalities as that of the plastic spherical mirror. 
   As used herein, the words “may” and “may be” are to be interpreted in an open-ended, non-restrictive manner. At minimum, “may” and “may be” are to be interpreted as definitively including structure or acts recited. 
   In order to understand this invention, reference is now made to  FIGS. 1 through 3 , which demonstrate the basic concept of the invention.  FIG. 1  illustrates this invention as applied to an aerial-image display system, generally designated as  10 , in the form which may be used for displaying objects, in the order of 12 inches in diameter as a practical maximum for this type of use. 
   The embodiment is contained within a housing, generally designated as  11 , having a window opening  12  in the front face and an image shelf  13  on a support arm  14  secured to the front lower panel  15 . The housing  11  is enclosed by a left panel  16 , a top panel  20 , two front panels  26  at the top, a lower panel  15 , two rear panels  21  and  22 , a right panel  23 , and a lower step panel  24 . Here, only the rear panel  21  appears in  FIG. 1 . The housing  11  is closed at the bottom by a bottom panel  25  appearing in  FIG. 2 . The window opening  12  is located in the upper front panel  26 . The panels mentioned so far, with the exception of the upper front panel  26 , are normally secured and not open during normal use or maintenance. The upper front panel  26  is hinged at its lower edge to allow it to be opened for possible cleaning of certain of the optics, if required. 
   The image shelf  13  is used as a visual reference and as a support for props to enhance the illusion, such as a vase for flowers, which is normally expected to rest upon a support. The image shelf  13  and its support arm  14  are optional, and for many applications their presence is undesired and may be removed. Such an embodiment appears in  FIG. 11 . 
   In the embodiment shown in  FIGS. 1-3 , each of the panels may be of plywood or particleboard, typically covered with plastic lamination having a suitable finish on the exterior as dictated by the environment. Most of the interior surfaces are finished in dull black to prevent unwanted reflections. 
   Referring again to  FIG. 1 , the stepped panel  24  includes a door  24 D, which provides access to an interior chamber designed to hold a VCR tape player providing the scene to be displayed on the video monitor of  FIG. 3  described below. 
   Referring now specifically to  FIG. 2 , it may be seen that the interior of the housing  11  includes basically a lower chamber or a first region  30  in which the object to be displayed or the source of the image is located, and an upper chamber or a second region  31 , in which the image from the source is transformed into the aerial image, which appears outside of the window opening  12 . Within the lower chamber  30 , the support structure  32  is rested on the base  25  and defines an electrical outlet chamber  33  and the VCR enclosure  34 . An additional storage space  35  is also provided. 
   The lower chamber  30  and the upper chamber  31  are separated by a platform  40 , including an image transfer opening  41 . The platform  40  provides a physical support for an apertured mirror support board  42 , which is shown exploded to the rear but is normally located at the rear of the upper chamber  31  and is supported by brackets  43 , which are secured to the side walls  16  and  23 , respectively. The mirror mounting board  42  has a large central, circular opening  44  dimensioned to receive a concave mirror  45 . 
   The upper chamber  31  also encloses a frame  50  that is used to support a partially reflective-transmissive beamsplitter mirror  51  of  FIG. 3 . The frame  50  is secured at a lower edge to a bracket  49 , which is attached to platform  40  and top panel  20 . The positioning of this frame  50  is better seen in  FIG. 3  and in detail in  FIG. 5 . 
   For an understanding of the optics of this invention, which makes possible the aerial image outside of the housing  11 , reference is now made to  FIG. 3 . In this embodiment of  FIG. 3 , the source of the image to be displayed is a video monitor  60  that is supported by a frame  61 . The source of the aerial-image electronic signal is the video tape player shown in an enclosure  34 . The image from the video monitor  60  is directed upward toward partially silvered mirror  51 , i.e., partly reflective means which reflects a part of the video monitor image to the concave mirror  45 . The mirror  45  reflects the image through the partly silvered mirror  51  and through the window opening  12  outward and into focus at a position VI above the image shelf  13  and approximately 18 inches in front of the window opening  12  in this embodiment. The mirror  45  and partially silvered mirror  51  constitute means for generating and directing the aerial image out of window  12 . 
   A viewer standing in front of the aerial-image display system  10 , within a horizontal audience angle of approximately 43 degrees, may see an aerial image appearing to be present above the image shelf  13 . The viewer looks at the window opening  12  and sees only a dark window  65  without any view of the mirror  45 , of any image within the housing or any reflected image of the observer. These are accomplished by the presence in the window  65  of an anti-reflective coating on a glass laminated optical circular-polarizing window  65 . A circular-polarizing layer CP window  65  causes any external light entering the housing  10  to be cancelled after reflection by the mirror  45 . 
   Likewise, the observer sees no image of the mirror  45  or other interfering images, while only the floating aerial image is present in front of the housing  11 . It is, therefore, submitted that the combination of the image source, the concave mirror, and the circularly-polarized anti-reflection window cooperate to provide the aerial image without any disturbing unwanted images. The circular-polarizing layer CP prevents external ambient illumination from being used by the observer from viewing the internal optical device, including a directing means mirror  45  and a half-silvered mirror  51 . Although not mandatory, an anti-reflective coating AR prevents the observer from seeing his image reflected in the window  12 . 
   Because of the confined nature of the housing, cooling air openings  70  in the baseboard  25  are present. An exhaust port  71  and an exhaust fan  72  at the top of chamber  30  are used to extract heat from the interior. In  FIG. 3 , the system  10  is shown with caster wheels  73  for mobility and also to elevate the base  25  above the supporting floor to aid in air movement. 
   Referring now to  FIG. 4 , the same basic system of this invention may be used in displaying actual objects, including the feature of showing rotation of the objects in front of the observer with certain changes in the system. In each case where the identical component is used in  FIG. 4  as in  FIGS. 1 through 3 , the same reference numbers are used. 
   In this case, no video monitor or any of its components are required. Instead, a bracket  111  and a turntable  112  are rotated by a motor  113 , which provides rotation at speeds such as 3 rpms. Any object DO located on a bracket  114  will form an aerial image VI shown above the image shelf  13  as clear and complete as the object itself presents. 
   In this embodiment, a pair of lamps  115  and  116  appears in  FIG. 10  and illuminates the display object DO, but only the lamp  115  appears in  FIG. 4 . The lamps  115  and  116  are typically of the internal reflector type, MR16, of lamp of 115V, 35 watt rating to produce a bright view of the object DO with limited beam spreading. Since the display object DO is located on the turntable  112 , the lamps  115  and  116  are directed at successive sides of the object, and the image appears as in ordinary ambient conditions. With proper angular positioning of the two lamps  115  and  116 , the entire surface of the object visible to the observer is clearly illuminated. To view the opposite side, the observer only needs to wait until the object rotates. 
   In  FIG. 4 , similar to  FIG. 3 , the image rays are designated by dashed lines from the object to the concave mirror  45  through the partially reflective mirror  51  or through a front window  65  with its circular polarized and anti-reflective coated glass  12 . 
   Objects to be displayed can be placed on the turntable with the turntable motor inoperative to provide the static aerial image of the display object. 
   One of the key elements of the optical system of this invention is the mirror  45 , which is simple and effective. The mirror  45  is made of glass with precise curvature and a reflective front surface coating to provide an accurate image. The mirror  45  is concave with the focal point at or near the image location VI. The mirror  45  is generally of rectangular shape when viewed from the front. The rectangular shape is defined by the shape available within a housing  11  to make it as large as possible and to provide a large, high-quality image. A highly reflective coating is used because of the inherent loss of light, due to inefficiency of the beamsplitter mirror  51 . A spherical shape is preferred, although other concave shapes may be used. 
   The mounting details of the mirror  45  may be better seen in  FIG. 9  where the mounting board  42  including the circular opening  44  and the mirror  45 , being concave and circular, rests in the opening  44  and is secured in place by a bead  80  of flexible adhesive, such as silicone cement, in which the mirror rests. There is a substantial surface contact behind the face of the mirror with the silicone adhesive in good contact between the inside surface of the board  42  and at the inside of the opening  44 . This also provides a degree of shock mounting of the mirror, while precisely holding the mirror in place. 
   The turntable assembly of  FIG. 4  may be best seen when viewed from the front side in  FIG. 8 . It is mounted on the bracket  111  with the turntable  112  itself constituting a flat plate of a diameter that is determined by the weight of the objects to be carried. Lightweight objects, e.g. 10 lbs. or less, can be supported on a turntable broader than one shown in  FIG. 8 , which is 11 inches in diameter. The bracket  111  is not seen by the observer, so it must be totally concealed below the display object DO. Likewise, the turntable  112  is not intended to be seen. Therefore, it is painted a dull black to blend in with the other background surfaces. 
   Positioned directly below the turntable is a direct drive motor  113 . The motor  113  may be of variable speed or single speed. It has been found that the single speed of three revolutions per minute is most effective for displaying objects for close examination and for dramatic effects. The observer is likely to examine objects with a magnifying glass for remarkable realism. 
   Reference is again made to  FIGS. 4 and 5  showing details of the optical elements of the system  110 . The front window  65 , with its anti-reflective front layer AR and its circular-polarize CP, is viewed by the observer as dark glass in the front opening  12  of the upper panel  26 . Behind the front window  65 , the partially reflective mirror  51  is in its frame  50 , which is installed at approximately a 50-degree angle with respect to the horizontal axis CL of the mirror  45 . These angles are determined primarily with respect to the desire to minimize the depth of the housing  11 , and this does not affect the optical properties of the system when the system is kept within the angular limits of the field rays with respect to the axis CL. 
     FIG. 4  also shows field rays FR which define the limits of field of the system  110  in which the image rays of the actual object must fall. The window  65  is a high-grade glass with an anti-reflective front surface AR and a laminated circular polarizer CP. The window  65  is secured by the brackets  49  to the front top panel  26 . As best seen in  FIG. 5 , it should be noted that the panel  26  is hinged at its bottom edge to the remainder of the housing  11  at the frame member  49 . The angled frame  50  is also secured to the frame  49  at its lower end and at its upper edge (not shown in  FIG. 5 ) to the underside of the top panel  20  of the housing  11  at the required angle. 
     FIG. 10  illustrates clearly the lamps  115  and  116  directed at approximately 45-degree angles with their beams directed at the display object DO on the turntable  112 . When the power cords  115 PC and  116 PC from the lamps  115  and  116  are connected to outlet boxes, the lamps  115  and  116  may be energized. When the power cord PC from the turntable motor  113  as shown in  FIGS. 4 and 10  is connected to one of a number of power outlet boxes contained within the housing  11  and energized, the turntable rotates under the light of the lamps  115  and  116 . These are all viewable in  FIGS. 4 and 10  with the lower front panel  15  partly broken away.  FIG. 4  also shows hinges indicated by dashed lines and the latch is for the top front panel  26 . 
     FIG. 11  illustrates either of the embodiments of  FIG. 3  or  4  without any image shelf  13  or support  14 . 
   As is described above in the background of the invention, this invention may be applied to many fields.  FIGS. 12 and 13  illustrate such an application for home appliances, a bedroom or a den clock radio, or for that matter usable in offices as well. The clock radio, generally designated as  120 , includes normal radio controls of an ON/OFF switch and a volume control  121 , a tuning knob  122 , and possibly a band selector switch on the near side. 
   An internal loudspeaker is positioned behind a speaker grill  124  in the form of an array of holes in a case  125 . The only departure from conventional clock radios in the appearance is the fact that the normal bezel or cover for the hands is replaced by a window  126 . The window  126  is not apparently transparent but presents a dark appearance to the observer within the field of view of this invention. 
   By incorporating this invention, the clock portion of the clock radio  120  appears as the aerial image VI of a clock face and hands in space in front of the window  126 . The aerial image VI will be spaced in front of the window and viewable by observers within the viewing angle of the window  126 . 
   Referring now to  FIG. 13 , it may be seen that the same optical elements found in the embodiments of  FIGS. 3 and 4  are present in this clock radio only on a smaller scale. The window  126  exhibits an anti-reflective coating AR on the outer face and a glass laminated circular polarizer CP. This window  126  thereby prevents the viewer from seeing his own image reflected in the window, allows the aerial image to be transmitted and circularly polarizes any external light that enters the window and reaches the internal concave mirror surface  130  from being reflected back into the room. The mirror  130  is formed as a part of the case  125  and metallized after the molding process in accordance with an established metalizing practice. 
   Similar to the beamsplitter  50  of  FIGS. 3 and 4 , a partially silvered beamsplitter  131  is disposed within the case  120 . The lower half of the case includes the clock motor  132  with its face  133  and hands  134 . Power to the clock motor  132  is supplied via leads CL. 
   One or more miniature lamps  140  are mounted on a rear wall  141  directed toward the clock face  133  to illuminate the clock face  133  and hands  134 . The circuit board and the components in the base of the case  125  represent the radio  150 , and the loud speaker  151  as shown is attached to the front wall of the case  125  behind the grill openings. 
   Now for a disclosure of another embodiment of this invention, please refer to  FIGS. 12 and 13 .  FIG. 12  is an isometric view of a personal aerial-image display device, such as a tabletop clock radio  120 , incorporating the aerial-image optics used in other versions of this invention. An aerial image VI of the clock hands and hour markers  134  of  FIG. 13  can be seen floating off the face of the housing or case  125 , formed by the light rays emerging through the window  126 . The radio contained within the housing is of conventional design, including the ON-OFF switch and the volume control  121 , the band selector switch (not shown in the drawing), the tuning knob  122  appearing in  FIG. 12 , and a tuning indicator  123  appearing in  FIG. 13 . 
     FIG. 13  is a vertical sectional view through the personal aerial-image display device  120  of  FIG. 12 . In  FIG. 13 , the displayed object is the clock  132  with a face  133  and the hands  134  horizontally mounted and illuminated internally by the lamp  140 . 
   Light travels vertically upward where it reflects off of a 45-degree beamsplitter horizontally rearward toward to a concave mirror  130  that is molded as a part of the housing  141  and is metallized. The light, which is focused by and reflects forward from the concave mirror  130 , is transmitted through the beamsplitter  131  and through the circular polarizing filter CP via the front window  126  to form the aerial image VI. 
   Still another embodiment of this invention may be seen in  FIGS. 14 and 15 . 
     FIG. 14  is an isometric view of a personal aerial-image display device, such as a tabletop television  120 TV, incorporating the aerial-image optical devices used in other versions of this invention. The aerial image VI of the liquid crystal display (LCD) television screen of  FIG. 15  can be seen in  FIG. 14  floating off the face of the television set  120 TV, formed by the light rays emerging through window  126 . 
     FIG. 15  is a vertical sectional view through the personal aerial-image display device of  FIG. 14 . In  FIG. 15 , the displayed object is the video display, which has built-in illumination. The light travels vertically upward where it reflects off of a 45-degree beamsplitter horizontally rearward toward to a concave mirror  130  which, similar to the radio embodiment of  FIGS. 12 and 13 , is molded as part of the housing  141  and is metallized. The light which is focused by and reflects forward from the concave mirror  130  is transmitted through the beamsplitter  131  and through the circular polarizing filter CP via the front window  126  to form the aerial image VI. 
   This display may be any type of video display, such as a cathode ray tube (CRT), a liquid crystal display (LCD), or such newer displays which become available, such as an organic light-emitting diode (OLED) display. 
   In  FIGS. 16 and 17 , versatility in design of this invention is represented.  FIG. 16  is a vertical section drawing through the housing of  FIG. 1 , indicating a video monitor  60  as an image source with one concave mirror facing downward rather than facing the window as is described in the previous embodiment. 
   In a previous version, as illustrated in  FIGS. 2-4  and  12 , only one concave mirror is used to form the image. In this system, the light traveling upward from the object  60  is transmitted through the 45-degree beamsplifter upward toward the concave mirror  45  which reflects it downward to be reflected off the 45-degree beamsplifter forward through the window or the opening  12  and the circular polarizing filter to form the floating image (the aerial image) VI. 
     FIG. 16  illustrates that the concave mirror has at least two different candidate locations to accommodate different housing limitations, while maintaining the same optical properties as the embodiment of  FIGS. 2-4 . 
   Where image brightness is an important factor, the embodiment of the invention shown in  FIG. 17  becomes one of the preferred embodiments.  FIG. 17  is a vertical section drawing through the housing  125  of  FIG. 1 , indicating a video monitor  60  as an image source, with two concave mirrors  45   a  and  45   b  to double the brightness of the display. In previous versions, as depicted in  FIGS. 2-4  and  12 , only one concave mirror is used to form the image. However,  FIG. 17  shows two mirrors in optically equivalent positions which cooperate to relay the image out in space. In the case of forward-facing mirrors  45   a , the light goes vertically upward from the object  60  and reflects off the 45-degree beamsplitter horizontally rearward toward concave mirror  45   a , which reflects it horizontally forward through the beamsplitter  51 , the window  12 , and the circular polarizing filter to form the floating image (the aerial image) VI. 
   In the case of the concave mirror  45   b , the light goes vertically upward from the object  60  and is transmitted through the 45-degree beamsplifter  51  upward toward the concave mirror  45   b , which reflects it downward to be reflected off the 45-degree beamsplitter forward through the window  12  and the circular polarizing filter to form the floating image (the aerial image) VI. In the previously described designs of  FIGS. 2-4  and  12 , the light would have been lost and absorbed in the black underside of the top  20  of the housing  110 . 
     FIG. 18  solves the problem encountered by retailers who intend to display objects, including jewelry, which are physically too small to be seen effectively from a distance.  FIG. 18  is a vertical section view through a video version of an aerial-image display  110 , in which there is a section where a small video camera VC is positioned to photograph the small objects DO on the miniature turntable  113 , and is illuminated by the light source  115 , all of which is light baffled in a separate chamber from the video display. 
   In operation, the retailers remove the rear access door  22 , place the displayed object DO on the turntable  113 , and replace the door  22 . The video camera is pre-focused on the middle of the turntable  113  where the displayed object DO is placed. The video signal from the camera VC goes to the video monitor  61  that displays a large image, which is relayed to the position VI by the same optical device as is used in the embodiments of  FIGS. 2-4  and  16  or  17 . 
   In the case where a human illusion is desired, the embodiment of  FIG. 19  is recommended.  FIG. 19  is a vertical sectional view through an aerial-image display  110 , indicating an illusion to create a talking head at the aerial-image position VI. The optics of using the beamsplitter  51 , the concave mirror  45   a , and the circular polarizing filter CP is as described before. A molded head is the displayed object DO. This head can be translucent and back projected with a video image from the video projector VP as shown, or opaque and front projected by a video projector (not shown). In the preferred configuration as shown, the head DO is molded or vacuum formed by translucent plastic without much detail in the facial features. This makes the generic head more adaptable, so as to project a variety of people&#39;s faces onto the back side of the molded head which acts like a rear-projection screen. 
   The video image may come from an internal VCR (shown in  FIG. 3 ). Nevertheless, this video-projector version has the advantage of being able to project streaming video and audio from a dedicated internet web site. In a situation where a large chain store operation would have the displays in many chain stores or fast-food restaurants, the video image of a celebrity or a recognizable character ( FIG. 19A ) could be video projected onto the molded face, which would be relayed optically outside of the display. This permits sponsors the opportunity to change the video message, or the person, at any time from their headquarters. To enhance the illusion, a headless mannequin HM, appropriately garbed, can be placed in front of the aerial-image housing  110  to complete the human figure. If the head DO is of flexible material, including opening lips, the head may be synchronized with audio, which can make the human figure appear life-like while speaking. 
   As an alternative, as illustrated in  FIG. 19 , in combination with  FIG. 19A , it is possible to employ a live actor in front of a video camera speaking the lines, which constitutes the audio channel that may communicate with the aerial display of  FIG. 19  via a suitable communication channel which may be any of a number of dedicated channels or may be via the Internet as indicated by the “www.” indication on the TV cable of  FIG. 19A . 
     FIGS. 20 and 21  illustrate alternate forms of the concave mirrors that may be used in carrying out this invention.  FIG. 20  is an alternate mirror construction where the concave mirror  45  is made from a thin membrane or a sheet  45 F of an aluminized film, such as the polyester material sold by the DuPont Co. under the trademark Mylar™. The Mylar™ mirror can be pulled into a concave curve, nominally of a partial spherical shape, by an exhaust fan  70  shown in an otherwise sealed chamber behind the film sheet  45 , or pushed into shape with a pressurizing fan (not shown), but otherwise located on the front (concave) side of the mirror  45 F. This film mirror  45 F has an advantage of being very lightweight and inexpensive, as compared with many mirrors of the size and quality required. 
     FIG. 21  is an alternate mirror configuration where the concave mirror  45 M is a molded plastic that has been coated with aluminum or other bright metals to form a mirror surface. Plastic mirrors are lighter weight, for the same thickness, and less susceptible to be broken than glass mirrors. 
     FIG. 22  shows a glass or otherwise a transparent-topped display case  200  used in retail stores (camera and jewelry stores, etc.). The displayed object DO is enclosed in a secure cabinet  210  and illuminated by the light source  215  located, for example, on a side wall and outside of the optical path from the displayed object DO to the optics of the system. 
   The light reflected off of the displayed object DO reflects off the underside of the partially reflective and partially transparent beamsplitter  251 , and reflects down toward concave mirror  245  which focuses and reflects the light upward at a forward angle through the beamsplitter  251  through a circular polarizing filter  265  and then through the horizontal glass top to form the aerial image VI. The user unlocks and removes an access door  222  and places the product DO on a turntable  212  which is rotated by a motor  213 . Switches on the back turn power onto fans (not shown), the lamp(s)  215 , and the turntable motor  213 . The circular polarizing filter  265  virtually blocks all room illumination, including the observer&#39;s own image, from being reflected and visible in the concave mirror  245 . 
     FIG. 23  is an isometric view of the glass-topped counter height, e.g. 30″-42″ height, display case  210  of  FIG. 22 . Air entrance holes  270 , the product-access door  222 , the glass top, and the openings in the opaque horizontal top surface just under the glass are visible through which the light emerges to form the aerial image VI. Note that the beamsplitter or the partly silvered mirror  251  is now positioned generally parallel to the glass top which acts as the window. The approximately 45-degree angular relationships of the beamsplitter are maintained with the object DO and the mirror  245 . 
   This embodiment is particularly suitable for the display of valuable items that may be damaged by excessive handling or of such value that security is of prime importance. The aerial image produced by this invention is so real that one is tempted to, and usually does, reach out in an attempt to touch it, only to their amazement witness their hand pass completely through the displayed object image. 
   In the present invention, an aerial-image display system with a plastic mirror is further provided. In the system, a method and a system for manufacturing a low-cost plastic spherical mirror of comparable performance as that of a glass spherical mirror are applied to the system. According to the present invention, a plastic injection molding method is used for manufacturing the plastic parts of a low-cost plastic spherical mirror. The plastic injection molding method is able to yield higher tolerance, improved process control, and higher repeatability. The metal mold for injection molding is able to hold a tight tolerance for a general envelope dimension for a mirror (not the mirror surface). The spherical radius tolerance is also able to be held at a tight tolerance. The aforementioned tolerances are comparable to that of the glass spherical mirrors. A metal mold for injection molding is able to be held to the tight tolerance as that of a glass spherical mirror. A detailed description for producing the plastic spherical mirror is provided hereinafter. 
   In an embodiment of the present invention, a plastic injection molding process is used for fabricating the plastic parts of a plastic spherical mirror. In the present embodiment of the present invention, the plastic injection molding process is capable of providing a dimensional tolerance of +/− 0.0001 inch for a parabolic plastic mirror that ranges from a diameter of from about five inches to about 36 inches, in certain embodiments of the present invention. Although the tooling for the plastic injection molding process is relatively expensive, the cost for each plastic parts manufactured is however very low. A plurality of complex geometries is reproducible using the plastic injection molding process according to an embodiment of the present invention and may be limited only by the manufacturability of a metal mold. 
   Plastic technologies, the available tools and materials have advanced, such that high-quality and low-cost plastic spherical mirrors in accordance with the present invention are now possible by selective combination. Through selecting metal mold tolerances, it is possible that the resulting plastic parts is specified and held in the tens of thousandths of an inch or better by carefully selecting the appropriate materials that are able to emulate the thermal stability and durability of glass. Preferably, the materials endure the type of operating conditions that in the past only glass spherical mirrors could have tolerated. 
   In an embodiment of the present invention, a metal mold&#39;s final finish may be implemented by means of machining and polishing or other similar finishing methods capable of producing an adequate finish quality, such as a superior grade or a grade that is considered as the finest finish available for a plastic parts. 
   In the embodiment of the present invention, parabolic plastic parts from about five inches to about 40 inches in diameter may be produced using the plastic injection molding process. The procedures of the plastic injection molding process are well known in the art; and therefore, detail description thereof is omitted herein. 
   In the present embodiment, a metal mold for plastic injection molding process must be machined to provide plus or minus 0.030 inch tolerance, or better, for a general envelope dimension and a spherical radius tolerance of plus or minus 0.05% for the plastic parts (not the mirror surface). The aforementioned tolerances are comparable to the glass spherical mirrors. The metal mold is capable of holding a tolerance of about +/− 0.0001 inch. 
   In an embodiment of the present invention, a plurality of plastic material formulations  50  may be used for fabricating the plastic spherical mirror in which a plurality of performance criteria are satisfied, such as material strength, thermal stability, water absorption, mold shrinkage, material flow into the mold, UL recognition, manufacturing considerations, surface density, lubricant content, and scratch resistance. In one embodiment, the plastic material, once the molding operation is complete, has 80/50 scratch dig or better. 
   In an embodiment of the present invention, the plastic material formulations may comprise one of the following: optical-grade polycarbonate, natural-grade polycarbonate, UV-grade polycarbonate, polyetherimide, glass-filled grade polyetherimide, PMMA (acrylic), and other comparable plastic materials having similar performance criteria. The selection of the plastic material formulation may be based on the degree of precision for the mold tooling as well as experimental results from part testing. In one embodiment, the plastic material has optical clarity and is substantially transparent. 
   In an embodiment of the present invention, a metal layer may be coated over the mirror surface of the trimmed plastic parts by performing a vacuum metallization or a vacuum deposition process or the plastic spherical mirror treated with an evaporated metal vapor. The thickness of the metal deposited on the plastic surface is preferably about four to eight microns. The metallization phase is followed by a spray coating of a protective overcoat on the metalized mirror surface. The protective coating may be a resist material or a plasticized liquid that hardens to a solid film layer upon exposure to room temperature. 
   The plastic parts that has been vacuum metalized may possess improved quality because of improved quality control of the surface of the plastic material that is being coated by means of the minimizing of the amount of flaws that are on the plastic surface resulting from the molding process. Furthermore, the metallization has excellent adhesion with respect to the mirror surface of the underlying plastic parts. Please refer to  FIG. 24  which illustrates embodiment of the present invention, a method for producing the plastic parts of the plastic spherical mirror according to the present invention.  FIG. 25 , on the other hand, illustrates an embodiment of a trimmed plastic parts for use for a plastic spherical mirror in accordance with the present invention, in which a plastic parts  280  and a surface thereof  282  are depicted. 
   Referring to  FIG. 24 , in the embodiment of the present invention, a method for producing the plastic spherical mirror, in which the plastic parts of relative thin thickness is to hold its form after it is heated and cooled, may include a plurality of the following steps. 
   Parts Design 
   a) A plastic parts is designed, such that the mirror surface is supported by a plurality of wall structures for preventing aberration and distortion thereof (S 100 ). The actual number of the wall structures varies according to the size of the mirror and may range from one for small mirrors to three or more for the larger mirrors. One skilled in the pertinent art will appreciate that the number of the wall structures is one of the engineering considerations and varies based on specific specifications. 
   b) A plurality of injection gates is designed and placed precisely with the intent of ensuring the elimination of remnants or knit lines created by plastic resin flow (S 102 ). The actual number of the injection gates varies according to the size of the mirror and may range from one for small mirrors to one or more for the larger mirrors. One skilled in the pertinent art will appreciate that the number of such injection gates is one of the engineering considerations and varies based on the particular specifications. In one embodiment, at least one injection gate is aligned with each of the wall structures; 
   c) A preferred physical size of the plastic parts is determined for satisfying a plurality of optical performance requirements and physical design requirements (S 104 ), including 80/50 scratch dig requirements and capability of maintaining the physical dimensions over time. 
   d) A plurality of support walls is designed and placed in the plastic parts, so that a final design dimension of the plastic parts has rigidity that matches that of a glass mirror (S 106 ). 
   Material Selection 
   a) The plastic material formulation is selected and used according to an ability to resist deformation according to a plastic parts quality specification (S 108 ). The plastic material may be an optical-grade plastic, such as those commonly used for cosmetic mirrors or other transparent plastic material. 
   Mold Tooling Processing 
   a) A metal mold is fabricated, including a mold cavity for forming the plastic parts according to the parts design described above, wherein the mirror surface of the metal mold is polished to a superior optical-grade finish (S 110 ). Preferably, the metal mold is made of grade A tool steel; 
   b) The m mold cavity is heated and/or cooled to form an optimal curvature on the mirror surface of the metal mold (S 112 ). 
   Plastic Injection Molding 
   a) The selected plastic material formulation is heated until a melt thereof is obtained, and a thin layer of a reflective metal coating is deposited onto the mirror surface of the plastic parts (S 114 ). 
   b) The melt is injected or forced into the mold cavity, and the melt is cooled to obtain the plastic parts of a desired size and shape (S 116 ). It should be understood that the injection process requires monitoring the temperature and flow rate of the melted plastic to maximize flow rate at the same time minimize turbulence. 
   c) The metal mold is opened to eject the plastic parts (S 118 ). 
   d) At least one surface is polished and mechanical machined to minimize surface defects (S 120 ). 
   Mirror Formation 
   a) A thin layer of a reflective metal coating is deposited on the mirror surface of the plastic parts to form a metalized mirror surface (S 122 ). 
   b) A protective overcoat is formed on the metalized mirror surface (S 124 ). The protective overcoat is a resist material or a plastic material that solidifies at room temperature to provide a protective barrier over the mirror prior to assembly. This protective overcoat is intended to be removed once the plastic spherical mirror is mounted in an aerial display unit. 
   Referring to  FIG. 26 , an embodiment of a modified plastic parts  25  used for the plastic spherical mirror in accordance with the present invention is illustrated. In  FIG. 26 , a method for fabricating the plastic spherical mirror according to another embodiment of the present invention is provided, in which the plastic parts has a thickness sufficient to hold its form/shape after being heated and cooled. In one embodiment, the concave region of the mirror has a thickness of 1.0 cm or less while the periphery may have a thicker thickness. In general, the fabrication of the plastic parts may include a plurality of the following steps. 
   Parts Design 
   a) The plastic parts is designed, such that the frame of the plastic parts is supported by a plurality of ejector pins (e.g. 28 ejector pins) disposed around the edge of the plastic parts for preventing distortion or twisting thereof, wherein the pins are facilitating parts removal from the metal mold without distorting the surface geometry or damaging the mirror surface finish (S 200 ); 
   b) A plurality of plastic injection gates is designed and placed accurately and evenly with the intent of ensuring the elimination of remnants or knit lines created by plastic resin flow (S 202 ); 
   c) A preferred physical size of the plastic parts is determined for satisfying a plurality of optical performance requirements and physical design requirements (S 204 ); 
   d) A plurality of support walls is designed and placed at strategical positions in the plastic parts (S 206 ); 
   Material Selection 
   a) Optical-grade polycarbonate, polyetherimide, or PMMA (acrylic) is selected as the plastic material formulation serving as the plastic spherical mirror (S 208 ). 
   Mold Tooling Processing 
   a) A metal mold is fabricated, including a mold cavity for forming the plastic parts according to the part design described above, wherein the mirror surface of the metal mold is fabricated using highly-graded steel to a superior finish (S 210 ). 
   b) The mold cavity is heated and/or cooled to form an optimal curvature on the mirror surface of the metal mold (S 212 ). 
   Plastic Injection Molding 
   a) The selected plastic material formulation is heated until a melt thereof is obtained (S 214 ). 
   b) The melt is injected or forced into the mold cavity, and the melt is cooled to obtain the plastic parts of the desired size and shape (S 216 ). 
   c) The metal mold is opened eject the plastic parts (S 218 ). 
   Mirror Formation 
   a) A thin layer of a reflective metal coating is deposited on the mirror surface of the plastic parts through vacuum metallization or vacuum deposition with a thickness of, preferably, four to eight microns to obtain a metalized mirror surface (S 220 ). 
   b) A protective overcoat is sprayed on the metalized mirror surface of the plastic parts (S 222 ). 
   Finished Parts Inspection 
   a) Sphericity on the mirror surface of the plastic spherical mirror is held at a tolerance of +/− 0.05% (S 224 ). 
   Referring to  FIG. 27 , a plastic parts formed by a plastic injection molding process in accordance with another embodiment of the present invention is illustrated, wherein a plurality of ejector pins are disposed around the edge of the plastic parts to facilitate parts removal from the metal mold without distorting the surface geometry or damaging the mirror surface. The actual number of ejector pins will vary depending on the size of the mirror and may range from three for small mirrors to four or more for the larger mirrors. One skilled in the art will appreciate that the number of such ejector pins are engineering considerations and will vary depending on the specific application. In one embodiment, the plastic parts includes a frame or a flange region that has a slightly thicker thickness than the central portion of the plastic parts. The flange is placed in contact with the ejector pins and is the only region where such ejector pins contact plastic parts. In another embodiment, a mold release agent is sprayed in to the mold prior to the molding process to facilitate removal of the plastic parts from the mold. 
   It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.