Patent Publication Number: US-2011057862-A1

Title: Image display device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an image display device, and more particularly an integrated image display device having both projecting system and head-mounted display. 
     2. Description of the Prior Art 
     Projectors are conventionally used in conference briefings in which a host projects data or graphics onto a screen for familiarizing attendants with a presentation. With the rapid development of technology, projectors are now widely used in other applications. With high-power hi-fi equipment, large-capacity digital video discs (DVDs), and the large images that can be generated by projectors, it is now possible to reconstruct at home visual and audio effects similar to those provided in a movie theater. 
     A head-mounted display (HMD), a three-dimensional visual optical device, is the first device providing its wearer with an immersive experience. The typical HMD houses two miniature display screens and an optical system that channels the images from the screens to the eyes, thereby presenting a stereo view of a virtual world. Recently, the head mounted display as an input apparatus in response to a user&#39;s action is widely utilized in an augmented reality or a virtual reality system. Continuously measuring the position and orientation of the user&#39;s head by means of a motion tracker allows an image generating computer to adjust a scene representation to a current view. As a result, the viewer can look around and walk through the surrounding virtual environment. In addition, text and images can be projected on a screen for viewing by the user therefore realizing an augmented reality or a virtual reality environment. 
     However, the projectors and head-mounted displays sold on the market are individual unit. If a consumer wishes to use functions from both devices at the same time, he or she needs to prepare two different set of equipments thereby causing a great deal of burden. Hence, how to provide a small and easy to carry image device with functions of both projector and head-mounted display has become a popular topic on consumer market. 
     SUMMARY OF THE INVENTION 
     It is an objective of the present invention to provide an integrated image display module for allowing users to enjoy functions of both projector and head-mounted display by using only one image device. 
     According to a preferred embodiment of the present invention, an image display device is disclosed. The image display device includes: an image processing unit; a projecting system; a head-mounted display; and a switch mirror disposed between the projecting system and the head-mounted display for switching lights projected from the image processing unit to the head-mounted display or the projecting system. 
     Another aspect of the present invention discloses an image display device, which includes: an image processing unit; a projecting system; a head-mounted display; and a beam splitter disposed between the projecting system and the head-mounted display for directing lights projected from the image processing unit to the head-mounted display and the projecting system simultaneously. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of an image display device module according to a first embodiment of the present invention. 
         FIG. 2  illustrates a perspective view of an image display device module according to a second embodiment of the present invention. 
         FIG. 3  illustrates a perspective view of an image display device module according to a third embodiment of the present invention. 
         FIG. 4  illustrates a perspective view of an image display device module according to a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 ,  FIG. 1  illustrates a perspective view of an image display device  10  module according to a first embodiment of the present invention. Preferably, the image display device  10  could be constructed to project three-dimensional pictures or regular two-dimensional pictures, and an embodiment for projecting three-dimensional pictures is explained below. As shown in  FIG. 1 , the image display device  10  includes an image processing unit  12 , a head-mounted display  14 , a projecting system  16 , and a switch mirror  18  disposed between the head-mounted display  14  and the projecting system  16 . The image processing unit  12  includes a light source  20 , a prism group  22 , and two liquid crystal on silicon (LCoS) display panels  24 . The light source  20  provides light required by the image display device  10 , in which the light source  20  could be composed of various light emitting elements including light emitting diodes (LEDs) or high intensity light bulbs. The prism group  22  is situated relative to the exit of the light source  20 . A polarizing beam splitter (PBS)  26  is coated on the prism group  22  to redefine the unpolarized light projected from the light source  20  into P-polarizing beam and S-polarizing beam. The defined P-polarizing beam and the S-polarizing beam are reflected from the two LCoS display panels  24  to the switch mirror  18 , and later reflected by the switch mirror  28  to the head-mounted display  14  or the projecting system  16 . 
     The head-mounted display  14  of the image display device  10  has at least one polarizer group  28  and a lens group  30 . The polarizer group  28  is composed of a polarizer  66  and a lens  68 , while the lens group  30  is composed of a reflecting mirror  70  and a lens  72 . The polarizer  66  of the polarizer group  28  preferably reflects the S-polarizing beam to the lens  68  while the reflecting mirror  70  of the lens group  30  preferably reflects the P-polarizing beam to the lens  72 . The S-polarizing beam and the P-polarizing beam focused by the lenses  68 / 72  are projected to the retina of the human eyes  32  to form enlarged images. 
     The projecting system  16  disclosed in this embodiment is preferably a micro-projector, in which the projecting system  16  is primarily composed of a projecting lens group  34  and a screen  36 . Similar to the manner of projecting light beams, P-polarizing beam and S-polarizing beam reflected from the switch mirror  18  are projected through the projecting lens group  34  and shown on the screen  36 . As three-dimensional images are shown on the screen  36 , surrounding audience could use 3D glasses to enjoy the image produced. 
     It should be noted that the intensity of light plays a dominating factor in the quality of images produced from the projecting system  16  and the head-mounted display  14 . For example, projecting system  16  has the tendency to produce better images by having a strong light source, whereas the head-mounted display  14  usually requires a weaker light source to prevent strong light beams from causing discomfort to the eyes of user. Therefore, the present invention preferably provides lights of different intensity to the projecting system  16  and the head-mounted display  14  as they are integrated. 
     According to an embodiment of the present invention, an attenuator  38  could be disposed between the switch mirror  18  and the head-mounted display  14  for adjusting the intensity of light entering the head-mounted display  14 . The attenuator  38  could be a variable attenuator used to produce different light intensity according to different time (such as daytime or nighttime) and environment (such as indoor or outdoor), or an optical film coated on surface of the switch mirror  18  with respect to the head-mounted display  14 , in which the attenuator  38  could be controlled automatically or manually through a sensor. The attenuator  38  of this embodiment is preferably coated on surface of the switch mirror  18 , but could also be coated on the polarizer  66  of the head-mounted display  14  adjacent to the eyes  32  of user, which is also within the scope of the present invention. 
     Preferably, as the switch mirror  18  is used to switch light to different targets (such as head-mounted display  14  or projecting system  16 ), the attenuator  38  is used to control the intensity of lights entering either the head-mounted display  14  of the projecting system  16 , such that the projecting system  16  would receive a relatively stronger lights whereas the head-mounted display  14  would receive relatively weaker lights. Despite the attenuator  38  is directly coated on surface of the switch mirror  18 , another attenuator  38  could also be placed on the polarizer  66  of the head-mounted display  14  regardless of whether attenuator is placed on the switch mirror  18 , which is also within the scope of the present invention. 
     In addition to using the attenuator  38  for controlling the intensity of lights entering the head-mounted display  14 , the switch mirror  18  could also be used for performing similar function. For example, a switch mirror  18  having at least two reflecting surface with different reflectivity could be provided to control the intensity of lights entering the head-mounted display  14  and the projecting system, such that the projecting system  16  would receive relatively stronger lights whereas the head-mounted display  14  would receive relatively weaker lights. This design preferably provides a similar outcome as the aforementioned embodiment of using attenuator. However, an attenuator  38  could also be disposed along with this design, which is also within the scope of the present invention. 
     Referring to  FIG. 2 ,  FIG. 2  illustrates an image display device  40  module according to a second embodiment of the present invention. Similar to the module disclosed in the first embodiment, the image display device  40  includes an image processing unit  12 , a head-mounted display  14 , a projecting system  16  and a switch mirror  18  disposed between the head-mounted display  14  and the projecting system  16 . The image processing unit  12  is composed of a light source  20 , a prism group  22 , and two LCoS display panels  24 . 
     The head-mounted display  14  of the image display device  10  has one polarizer group  28  and a lens group  30 , in which the polarizer group  28  is composed of a polarizer  66  and a lens  68  while the lens group  30  is composed of a reflecting mirror  70  and a lens  72 . The polarizer  66  of the polarizer group  28  preferably reflects the S-polarizing beam to the lens  68  while the reflecting mirror  70  of the lens group  30  preferably reflects the P-polarizing beam to the lens  72 . The S-polarizing beam and the P-polarizing beam focused by the lenses  68 / 72  are projected to the retina of the human eyes  32  to form enlarged images. The projecting system  16  disclosed in this embodiment is preferably a micro-projector, in which the projecting system  16  is primarily composed of a projecting lens group  34  and a screen  36 . Similar to the manner of projecting light beams from the head-mounted display  14 , P-polarizing beam and S-polarizing beam reflected from the switch mirror  18  are projected through the projecting lens group  34  and shown on the screen  36 . 
     In this embodiment, a light source control unit  48  is connected to the light source  20  of the image processing unit  40  for controlling the intensity of the light entering the projecting system  16  or the head-mounted display  14 , in which the light source control unit  48  is preferably composed of a switch  42 , a high voltage source  44  and a low voltage source  46 . If the projecting system  16  requests a stronger light source, the switch  42  could be utilized to provide larger current to the light source  20  for transmitting light of strong intensity to the projecting system  16 . Conversely, a small current could be provided to the light source  20  through the switch  42  for transmitting weaker lights to the head-mounted display. 
     Referring to  FIG. 3 ,  FIG. 3  illustrates a perspective view of an image display device  50  module according to a third embodiment of the present invention. In this embodiment, the image display device  50  includes an image processing unit  12 , a head-mounted display  14 , a projecting system  16 , and a beam splitter  52  disposed between the head-mounted display  14  and the projecting system  16 . The image processing unit  12  includes a light source  20 , a prism group  22 , and two liquid crystal on silicon (LCoS) display panels  24 . The light source  20  provides light required by the image display device  50 , in which the light source  20  could be composed of various light emitting elements including light emitting diodes (LEDs) or high intensity light bulbs. The prism group  22  is situated relative to the exit of the light source  20 . A polarizing beam splitter (PBS)  26  is coated on the prism group  22  to redefine the unpolarized light projected from the light source  20  into P-polarizing beam and S-polarizing beam. The defined P-polarizing beam and the S-polarizing beam are reflected from the two LCoS display panels  24  to the beam splitter  52 , and later reflected by the beam splitter  52  to the head-mounted display  14  and the projecting system  16  simultaneously. 
     In contrast to the aforementioned embodiments shown in  FIGS. 1-2  of using the switch mirror  18  to reflect lights to the head-mounted display  14  or the projecting system  16  separately, such that only one function of the device could be used at a time, this embodiment preferably uses the beam splitter  52  to provide lights with different intensity to the head-mounted display  14  and the projecting system  16  simultaneously, thereby allowing users to enjoy these two functions at the same time. Preferably, the two surfaces of the beam splitter  52  corresponding to the head-mounted display  14  and the projecting system  16  could be fabricated with different reflectivity and transparency to provide different intensity of lights to the head-mounted display  14  and projecting system  16 . Moreover, an additional attenuator could be disposed selectively in the head-mounted display  14 , which is also within the scope of the present invention. 
     Referring to  FIG. 4 ,  FIG. 4  illustrates a perspective view of an image display device  60  module according to a fourth embodiment of the present invention. In this embodiment, the image display device  60  includes an image processing unit  12 , a head-mounted display  14 , a projecting system  16 , and a beam splitter  52  disposed between the head-mounted display  14  and the projecting system  16 . The image processing unit  12  includes a light source  20 , a prism group  22 , and two liquid crystal on silicon (LCoS) display panels  24 . The light source  20  provides light required by the image display device  60 , in which the light source  20  could be composed of various light emitting elements including light emitting diodes (LEDs) or high intensity light bulbs. The prism group  22  is situated relative to the exit of the light source  20 . A polarizing beam splitter (PBS)  26  is coated on the prism group  22  to redefine the unpolarized light projected from the light source  20  into P-polarizing beam and S-polarizing beam. The defined P-polarizing beam and the S-polarizing beam are reflected from the two LCoS display panels  24  to the beam splitter  52 , and later reflected by the beam splitter  52  to the head-mounted display  14  and the projecting system  16  simultaneously. 
     In this embodiment, an optical fiber  62  is connected to the head-mounted display  14  and the projecting system  16  for controlling the operation of these two units. The optical fiber  62  is preferably utilized to control the head-mounted display  14  and the projecting system  16  remotely, but not limited thereto. Additionally, the head-mounted display  14  and the projecting system  16  could be controlled through physical connection of HDMI signal lines or other signal lines, or could be controlled through wireless transmission. In other words, a physical connection or remote control means could be established to control only the head-mounted display  14 , only the projecting system  16 , or both the head-mounted display  14  and the projecting system  16  simultaneously. An image enhancer  64  could also be connected to the optical fiber  62  to enhance the image quality of the image display device  60 . It should be noted that despite only one single connection is established between the optical fiber  62  and the head-mounted display  14  in this embodiment, multiple connections could also be achieved by connecting the optical fiber  62  with a plurality of head-mounted displays  14  and/or projecting systems  16  to allow multiple of users to enjoy both functions simultaneously. Lastly, it should be noted that all devices and quantity, size and corresponding position of the module disclosed in the aforementioned embodiments are not limited by the figures presented. The presented figures are merely for exemplary purpose and other design and arrangement achieving analogous functionality could also be applied to the device of the present invention accordingly, which is also within the scope of the present invention. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.