Patent Publication Number: US-7717570-B2

Title: Image projector display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application is a U.S. continuation patent application of, and claims priority under 35 U.S.C. §120 to, U.S. patent application Ser. No. 11/850,912, filed on Sep. 6, 2007, now U.S. Pat. No. 7,478,912 on Jan. 20, 2008, which &#39;912 application published as U.S. patent application publication 2008/0024734, and which &#39;912 application is a U.S. continuation patent application of, and claims priority under §120 to, U.S. patent application Ser. No. 11/209,837, filed on Aug. 24, 2005, now U.S. Pat. No. 7,267,444, and which &#39;837 application is a nonprovisional application of, and claims priority under 35 U.S.C. §119(e) to, U.S. provisional patent application 60/604,495, filed on Aug. 26, 2004. 
   The disclosure of each of the above mentioned U.S. patent applications, any and all publications thereof, and patents is hereby incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention generally relates to projecting an image onto a surface that is substantially parallel to an axis of light passing through an objective lens, and more particularly to projecting an image from an image representation onto a surface where the angle from one portion of the image representation to the surface is different than the angle from at least one other portion of the image representation. 
   2. Description of Related Art 
   A typical image projector will shine a light source towards an image representation, such as a slide or transparency. The light then passes through an objective lens that will magnify the image representation to display an image on a surface. 
   A well-known image projector currently available is a slide projector. An optical path for a typical slide projector is shown in  FIG. 1 . 
   Normally, a slide projector comprises a light source  101  that projects light towards a slide  109  that includes a representation of an image. The light source  101  may have a reflective mirror (not shown) to reflect scattered light back towards the slide, and a lens  105  may be interposed between the light source  101  and the slide  109  to further concentrate light onto the slide. While a condenser lens is shown, a no-sphere (planoconvex) lens could also be used for this purpose. The light beam then passes through a projection/objective lens  115  that magnifies the image and projects it for display onto a surface  120 , like a screen or wall. A field lens (not shown) could also be provided that further focuses the entire light beam passing through the slide  109  onto the objective lens  115 . The light source  101 , slide  105 , and objective lens  115  are aligned along a common axis of light. This axis is substantially perpendicular to the surface  120  onto which the image is projected. 
   Another type of well-known projector is an overhead projector (not shown). Generally, the transparency is substantially perpendicular to the projected image. The light source will shine up through an image representation, which is normally referred to as a transparency, to a housing containing the lenses for projecting the image. The overhead lens housing will include some kind of condenser lens, normally a fresnel lens, to collect light shined through the transparency and direct it to a pupil of an objective lens. The objective lens then projects the image much in the sane way as the objective lens in the slide projector. A mirror is then used to redirect the image projected from the objective lens so that the final projected image can be displayed on the surface, which is substantially perpendicular to the transparency. But like a slide projector, the plane of the surface is substantially perpendicular to the direction of light projecting the image from the overhead projector. 
   In both the slide projector and the overhead projector, the projected image can be easily focused because the distance from the objective lens to the surface is substantially similar for the entire projected image. Therefore, the entire projected image can be at a substantially similar distance from a focal point of the objective lens. 
   The arrangement of either the slide projector or the overhead projector, however, would not be suitable for projecting an image onto a surface that is substantially parallel to the direction of light projected to display an image. Some portions of the projected image would be much closer to the objective lens, while other portions would be much further from the objective lens. This would distort the image so that the image projection portions closer to the objective lens would appear shortened, and the portions further from the objective lens would appear elongated. As a result, the projectors described above would display the image on a substantially parallel surface with a “fun-house” mirror like effect. 
   To properly display an image on the substantially parallel surface, a display device like an image projector must account for the varying distances throughout the image projection from the projection/objective lens. 
   SUMMARY OF THE INVENTION 
   The invention avoids the disadvantages and drawbacks of the related art by allowing a proper display of an image. 
   The invention thus provides a device for projecting an image onto a surface that is substantially parallel to an axis of the light passing through the objective lens. 
   According to an aspect of the invention, a device for displaying an image includes a light source, an image representation disposed in a path of light emitted from the light source, and an objective lens disposed proximate the image representation to project an image projection onto a surface substantially parallel to the path of light emitted from the light source through the image representation and the objective lens, wherein the image projection is substantially similar to the image. 
   The device may further include a reflection mirror reflecting light emitted from said light source toward the image representation. The device may also include a planoconvex lens disposed between said light source and the image representation, and adjacent to the image representation. In addition, a fresnel lens may be disposed between the image representation and the objective lens. The light source may be a light emitting diode. The distance from the light source to a center of the objective lens is at a range of about 75 mm and about 225 mm. The image representation may be a distorted representation of the image, or the image representation may be substantially similar to the image. The image projection may be at least about 15 times greater in size than said image representation. An angle between an axis of light projected from a center of the objective lens and the surface may be less than about 10 degrees. 
   According to another aspect of the invention, a device for displaying an image includes a means for emitting light, such as a light bulb, LED or the like, a means for representing the image, such as an image representation slide, disposed in a path of light emitted from the light emitting means, and a means for projecting the image, such as an object lens, disposed proximate the image representation means to project an image projection onto a surface substantially parallel to the path of light emitted from the light emitting means through said image representation means and said image projecting means, wherein the image projection is substantially similar to the image. 
   The device may also include a means for projecting light, such as a reflection mirror or a condenser lens, from said light emitting means towards said image representation means. The device may also include a means for diffracting light, such as a fresnel lens, to orient an angle of light incident to said image projecting means. The device may also include a means for concentrating light, such as a condenser lens, projected from said light projecting means towards said image representation means. In addition, the distance from the light emitting means to a center of the image projecting means is at a range of about 75 mm and about 225 mm. The projected image may be about 15 times greater in size than said image representation means. Further, an angle between an axis of light projected from a center of said image projecting means and the surface is less than about 10 degrees. 
   A further aspect of the invention provides a night light for displaying an image including a light emitting diode (LED), a representation of the image disposed in a path of light emitted from the LED, an objective lens disposed proximate the representation of the image to project a projected image onto a surface substantially parallel to the path of light emitted from the LED through the representation of the image and the objective lens, and an orientation lens that orients an angle of light incident to the objective lens, wherein the projected is substantially similar to the image. 
   The night light may also include a reflection mirror reflecting light from the LED toward the representation of the image and a concentration lens that concentrates light from the LED onto the representation of the image. The night light may further include a condensing lens disposed between the LED and the representation of the image. 
   Additional features, advantages and embodiments of the invention may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed. For example, while the invention was developed to solve certain problems in night light displays, it may be used in other applications and with other devices where an image display is desirable. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the detailed description serve to explain principles of the invention. No attempt is made to show structural details of the invention in more detail than may be necessary for a fundamental understanding of the invention and the various ways in which it may be practiced. In the drawings: 
       FIG. 1  illustrates an optical path of typical slide projector; 
       FIG. 2  illustrates a front elevational view of an image display device according to principles of the invention; 
       FIG. 3  illustrates a side elevational view of an optical path for an image display device according to an embodiment of the invention; 
       FIG. 4  illustrates a representative view of an angle between the projection surface and an objective lens according to an embodiment of the invention; and 
       FIG. 5  illustrates a side elevational view of an optical path for an image display device according to another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The embodiments of the invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and examples that are described and/or illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of well-known components and processing techniques may be omitted so as to not unnecessarily obscure the embodiments of the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the embodiments of the invention. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the invention, which is defined solely by the appended claims and applicable law. Moreover, it is noted that like reference numerals represent similar parts throughout the several views of the drawings. 
   The invention discloses an image display device that displays an image onto a surface that is substantially parallel to the direction of light passing through a representation of an image and the projection/objective lens. Examples of such devices include, but are not limited to, night lights, floor or desktop mounted displays, advertisement displays, and the like. 
     FIG. 2  shows an image projector according to principles of the present invention. The display device  200  can be plugged into a standard electrical socket  201  to upwardly project an image  209  along a wall proximate the display device. Other types of power supplies, such as one or more batteries, may also be used. While the drawing shows an upwardly projected image, the invention can be used to project the image along the wall and/or ceiling in any direction. Moreover, the invention may provide a single display device that can project the image in varying directions. 
   The display device  200  may be capable of projecting an image from a single, fixed image representation of an image, like a slide. Alternatively, the representation of the image can be removable so that any number of images could be displayed by a single display device by simply changing the slide. The images projected by the display device  200  may be of, for example, any theme or figure related to sports, vehicles, cartoons, movies, politics, nature, holiday, fantasy, art, music, science fiction, and locations. 
   According to an embodiment of the invention, multiple slides may be used and alternated so that the projected image changes. By way of one example, a slide may include a digital memory that holds one or more digital images. Images from the memory are displayed within the slide, such as in a manner similar to computer implemented projectors. The slide has a processor for automatically changing the images displayed on the slide, thereby changing the images projected. The slide may have an input to enable a user to upload images, such as from a digital camera or computer, thereby allowing customization of the image or images to be projected. 
   The display device  200  may have a decorative housing  205 . Here, the housing  205  is a stock racing car projecting the image  209  of a celebrating driver through its windshield. Other embodiments may also be used. 
   The housing  205  may be designed to relate to the image and/or images projected. For example, the display shell may have a design related to, for example, any sports theme, vehicle theme, cartoon theme, movie theme, political theme, nature theme, holiday theme, fantasy theme, art theme, music theme, science fiction theme, and location theme. The housing  205  may be fabricated from any material suitable for a projection display device such as plastic, ceramic, metal, or glass. The housing  205  may also be adapted in any suitable manner to allow light to pass through a portion thereof to permit the projection of an image. 
   The display device  200  illustrated in  FIG. 2  has a night light structure that is plugged directly into the socket. According to an embodiment of the invention, a separate display device may be provided using a desk lamp type structure that can be powered, for example, by a battery or via an electrical cord. The housing  205  can also be adapted to let another electrical device to be plugged into display device  200 . 
   Now an optical path of the display device according to an embodiment of the invention will be described. As can be seen in  FIG. 3 , optical path  300  includes a light source  301  that shines a light towards the representation of the image or slide  309 . Because the light emitted from the light source  301  scatters in all directions, a reflection mirror  303  may be provided to reflect scattered light back towards the slide. Any light source can be used, including, but not limited to, an incandescent bulb, a fluorescent bulb, a neon (i.e., inert gas) bulb, a halogen bulb, and a light emitting diode (“LED”). The electrical components provided, such as one or more ballasts, will depend on the type of light source selected, as is well-known by those persons having ordinary skill in the art. An LED may be advantageous, however, because of its low power consumption, low heat emission, and high luminance properties as compared to other types of light sources. 
   Another lens, such as lens  305 , can be interposed between the light source  301  and slide  309  to concentrate light onto to the slide. This lens may be an optical lens, such as a planoconvex lens. The light passes through slide  309  and strikes a fresnel lens  313  at an angle with respect to the slide  309 . The angle can be anywhere from about zero (0) degrees to ten (10) degrees but an angle of about zero (0) degrees is shown. The fresnel lens  313  changes the direction of light and focuses it towards the projection/objective lens  315 . The objective lens  315  has a surface, which may be asymmetrical, and can be at an angle of about zero (0) degrees to about twenty (20) degrees, but an angle of about ten (10) degrees is shown. Ideally, the fresnel lens  313  is disposed at substantially the same angle as the objective lens  315 . Light then passes through the objective lens  315  where the image is projected onto the substantially parallel surface. 
   According to an embodiment of the present invention, the distance from the light source  301  to the center of objective lens  315  is in the range of about 75 mm and about 225 mm, more specifically in the range of about 112.5 mm and about 187.5 mm, and more specifically about 150 mm. But any distance may be suitable depending on, for example, the desired size of the image projection, the size of the slide, or the focal length of the objective lens. According to an embodiment of the invention, the projected image may be at least about 15 times larger than the image representation, and more specifically the projected image may be at least about 30 times larger than the image representation. 
   Accordingly, the optical path  300  accommodates the vary distances of the portion of a surface onto which the image is projected by angling a path of light projecting from the objective lens  315  to display an image. Such an arrangement eliminates the “fun-house”mirror effect distortion and permits display of a substantially focused image. 
     FIG. 4  illustrates an angle a of the common optical axis  317  of the slide  309  and objective lens  315  in relation to the surface  320  upon which the image  330  is projected. 
   Because the display device of the invention can be used as a night light proximate the wall  320 , the display device must be able to project a substantially clear image at a highly acute, tight angle that is substantially parallel to the surface. Here, the angle .alpha. is shown to be about 5.7 degrees, but the display device of the invention is suitable for projecting the image  330  when the angle between the common optical axis  317  and the surface  320  is at other angles, such as less than about 10 degrees. 
   Now an optical path of the display device according to another embodiment of the invention will be described. Looking at  FIG. 5 , optical path  400 , includes a light source  401  projecting light towards a condenser lens  405  that collects emitted light. The light collected by the condenser lens  405  then passes through a light adjusting lens  406  that concentrates light on the slide  409 . The light beam passing through the slide  409  then passes through a grating lens  413 . The grating included on lens  413  diffracts the light so that it strikes projection/objective lens  415  at an angle. This angle may be about zero (0) degrees to about ten ( 10 ) degrees but an angle of about zero (0) degrees is shown. The grating diffracts the light at a number of angles accounting for the varying distances of the surface portions onto which the image is projected. Light then passes through the objective lens  415  to project the image onto the substantially parallel surface  420 . 
   While the invention has been described in terms of particular embodiments, those skilled in the art will recognize that the invention can be practiced with modifications in the spirit and scope of the appended claims. These examples given above are merely illustrative and are not meant to be an exhaustive list of all possible designs, embodiments, applications, or modifications of the invention.