Abstract:
The disclosure provides a light modulating module attached on a display side of a reflective display apparatus, including: a light source portion capable of providing an illumination light beam, wherein the illumination light beam is capable of being transmitted to the reflective display apparatus, and the reflective display apparatus is adapted to reflect the illumination light beam to generate an image light beam; and an image light modulating device is disposed above the reflective display apparatus and disposed in a light path of the image light beam, wherein the image light modulating device is capable of modulating a direction and/or a polarization state of the image light beam, and the image light beam is emitted to either a left or right eye of a viewer to form an autostereoscopic image perceivable to the viewer after the image light beam passes through the image light modulating device.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The disclosure relates to a 3D image display, and in particular relates to a light modulating module thereof. 
     2. Description of the Related Art 
     Displays capable of showing stereoscopic images or animations are called three-dimensional (3D) image displays. Major developments in the 3D display fields have led to two types of technologies: a polarized glasses type and a naked-eye type. Meanwhile, 3D display effects may also be theoretically accomplished by using holography. However, holography needs interference of several light beams to display 3D images. 
     In the conventional 3D image displays, whether the naked-eye type or the polarized glasses type, a light modulating module is fixed on a display apparatuses. A user cannot view 3D images by an original 2D image display. The only way to view 3D images is buy a new 3D image display. Accordingly, a moveable light modulating module capable of being attached on a 2D image display to perform 3D images is called-for. 
     BRIEF SUMMARY OF THE INVENTION 
     One embodiment of the disclosure provides a light modulating module, adapted to be attached on a display side of a reflective display apparatus, comprising: a light source portion capable of providing an illumination light beam, wherein the illumination light beam is capable of being transmitted to the reflective display apparatus, and the reflective display apparatus is adapted to reflect the illumination light beam to generate an image light beam; and an image light modulating device disposed above the reflective display apparatus and disposed in a light path of the image light beam, wherein the image light modulating device is capable of modulating a direction and/or a polarization state of the image light beam, wherein the image light beam is emitted to either a left or right eye of a viewer to form an autostereoscopic image perceivable to the viewer after the image light beam passes through the image light modulating device. 
     One embodiment of the disclosure provides a stereoscopic display module adapted to be applied to a reflective display apparatus, comprising: the described light modulating module; and a stereoscopic glasses comprising a right eye glass capable of transmitting the image light beam having a first polarization state and a left eye glass capable of transmitting the image light beam having a second polarization state, wherein the first polarization state is different from the second polarization state, wherein the image light beam is emitted to either a left or right eye of a viewer to form an auto stereoscopic image perceivable to the viewer after the image light beam is emitted out from the image light modulating device and passes through the stereoscopic glasses. 
     One embodiment of the disclosure provides an image display comprising: a reflective display apparatus, comprising a display panel having a plurality of pixels; and a light modulating module, disposed on the reflective display apparatus, comprising: a light source portion capable of providing an illumination light beam, wherein the illumination light beam is capable of being transmitted to the reflective display apparatus, and the reflective display apparatus is adapted to reflect the illumination light beam to generate an image light beam; and an image light modulating device disposed above the reflective display apparatus and disposed in a light path of the image light beam, wherein the image light modulating device is capable of modulating a direction and/or a polarization state of the image light beam, wherein the image light beam is emitted to either a left or right eye of a viewer to form an auto stereoscopic image perceivable to the viewer after the image light beam passes through the image light modulating device. 
     One embodiment of the disclosure provides an image display system, comprising: a reflective display apparatus, comprising a display panel having a plurality of pixels; and a light modulating module, disposed on the reflective display apparatus, comprising a light source portion capable of providing an illumination light beam, wherein the illumination light beam is capable of being transmitted to the reflective display apparatus, and the reflective display apparatus is adapted to reflect the illumination light beam to generate an image light beam; an image light modulating device disposed above the reflective display apparatus and disposed in a light path of the image light beam, wherein the image light modulating device is capable of modulating at least one of the direction and the polarity of the image light beam; and a stereoscopic glasses comprising a right eye glass capable of transmitting the image light beam having a first polarization state and a left eye glass capable of transmitting the image light beam having a second polarization state, wherein the first polarization state is different from the second polarization state, wherein the image light beam is emitted to either a left or right eye of a viewer to form an auto stereoscopic image perceivable to the viewer after the image light beam is emitted out from the image light modulating device and passes through the stereoscopic glasses. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIGS. 1-10  show image displays in embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       FIG. 1  shows an image display of one embodiment in the disclosure. A light modulating module B is attached on a reflective display apparatus A including a display panel having a plurality of pixels. The reflective display can be an electrophoretic electronic ink display, a chlorestic liquid crystal display, or the likes. The light modulating module B includes a light source portion I and an image light modulating device such as a reflective polarizer  3 . The light source portion I emits an illumination light beam  100  to be transmitted to the reflective display apparatus A and then reflected to generate an image light beam. A polarization state of the image light beam is then modulated by the reflective polarizer  3  in a light path of the image light beam, such that the image light beam is then emitted to either a left or right eye of a viewer to form an auto stereoscopic image for the viewer after the image light beam passes through the reflective polarizer  3 . 
     In one embodiment, the light source portion includes a plane light source  200  disposed between the image light modulating device B and the reflective display apparatus A. The plane light source  200  may include a light emitting device  1  and a light guide device  2 . The light emitting device  1  can be a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an exterior electrode fluorescent lamp (EEFL), or the likes. The light guide device  2  includes an image light emitting surface  2 A, an image light incident surface  2 B opposite to the image light emitting surface  2 A, and an illumination light incident surface  2 C perpendicular to the image light incident surface  2 B and the image light emitting surface  2 A. As shown in  FIG. 1 , the light emitting device  1  is disposed adjacent to the illumination light incident surface  2 C of the light guide device  2 . As such, an illumination light beam  100  emitted by the light emitting device  1  travels through the illumination light incident surface  2 C and the image light incident surface  2 B, and then enters the reflective display apparatus A. The illumination light beam  100  is then reflected to generate an image light beam. The image light beam, traveling through the image light incident surface  2 B and the image light emitting surface  2 A, is then modulated by the reflective polarizer  3  to be emitted to either a left or right eye of a viewer to form an auto stereoscopic image for the viewer. In one embodiment, the light guide device  2  further includes a plurality of microstructures  2 D disposed on the image light incident surface  2 B. Furthermore, the microstructures  2 D include a plurality of quantum dots having a distribution density increasing along a direction away from the illumination light incident surface. In other words, the quantum dots distribution near the top of the microstructures  2 D is denser than that near the bottom of the microstructures  2 D. The microstructures  2 D and the quantum dots thereof may further enhance a uniformity of the image light beam distribution. 
     The reflective polarizer  3  can be a linear reflective polarizer or a circular reflective polarizer. In one embodiment, the reflective polarizer  3  includes a first portion and a second portion. The first portion substantially reflects the image light beam having a first polarization state and substantially transmits the image light beam having a second polarization state. The second portion substantially reflects the image light beam having the second polarization state and substantially transmits the image light beam having the first polarization state. The first polarization state is different from the second polarization state. In one embodiment, the reflective polarizer  3  can be a wire grid polarizer including a wire grid disposed on a substrate. As shown in  FIG. 2 , the wire grid includes a plurality of wires  201 A aligned in parallel corresponding to a first direction in the first portion  203 A, and a plurality of wires  201 B aligned in parallel corresponding to a second direction in the second portion  203 B, respectively. The wires  201 A and  201 B can be composed of an electrically conductive material, e.g. metal such as aluminum, silver, and gold. The wires  201 A and  201 B can be nano-sized wires separated by nano-scaled spaces  205 . For example, the spaces  205  may have a width of 10 nm to 250 nm, and the ratio of the wires  201 A and  201 B to the spaces  205  is 25% to 75%. In another embodiment, the reflective polarizer  3  includes first and second portions of the multi-layered stack of alternating layers comprising a first material and a second material with different refractive indexes. The first portion of the multi-layered stack of alternating layers substantially reflects the image light beam having a first polarization state and substantially transmits the image light beam having a second polarization state. The second portion of the multi-layered stack of alternating layers substantially reflects the image light beam having a second polarization state and substantially transmits the image light beam having a first polarization state. The first polarization state is different from the second polarization state. For an example of the reflective polarizer  3 , reference may be made to U.S. Pat. No. 5,122,905. When the reflective polarizer  3  is selected as the image light modulating device, a viewer should wear stereoscopic glasses including a right eye glass and a left eye glass. The right eye glass transmits the image light beam having the first polarization state, and the left eye glass transmits the image light beam having the second polarization state. 
     In one embodiment, the reflective polarizer  3  substantially reflects an image light beam having a first polarization state and substantially transmits an image light beam having a second polarization state. The first polarization state is different from the second polarization state. Still in this embodiment, the image light modulating device further includes a fractional wave plate  4  disposed on the reflective polarizer  3 , as shown in  FIG. 3 . The fractional wave plate  4  includes a quarter wave plate or a half wave plate, such that half of the image light beam having the first polarization state is transferred to an image light beam having the second polarization state. In one embodiment, the reflective polarizer  3  can be a wire grid polarizer including a wire grid disposed on a substrate. As shown in  FIG. 4 , the wire grid includes a plurality of wires  201 A aligned in parallel corresponding to a first direction in all portions. In another embodiment, the reflective polarizer  3  is a multi-layered stack of alternating layers comprising a first material and a second material with different refractive indexes. For an example of the reflective polarizer  3 , reference may be made to U.S. Pat. No. 5,122,905. When the reflective polarizer  3  and the functional wave plate  4  are selected as the image light modulating device, a viewer should wear stereoscopic glasses including a right eye glass and a left eye glass. The right eye glass transmits the image light beam having the first polarization state, and the left eye glass transmits the image light beam having the second polarization state. 
       FIG. 5  shows an image display of one embodiment in the disclosure. A light modulating module B is attached on a reflective display apparatus A including a display panel having a plurality of pixels. The reflective display can be an electrophoretic electronic ink display, a chlorestic liquid crystal display, or the likes. The light modulating module B includes a light source portion I and an image light modulating device such as a light directing device  5 . The light source portion I emits an illumination light beam  100  to be transmitted to the reflective display apparatus A and then reflected to generate an image light beam. A direction of the image light beam is then modulated by the light directing device  5  in a light path of the image light beam, such that the image light beam is then refracted to either a left or right eye of a viewer to form an auto stereoscopic image for the viewer after the image light beam passes through the light directing device  5 . The light source portion is similar to the previously described embodiment and omitted here. The light directing device  5  can be a lenticular film having a plurality of microlenses, a plurality of prisms, or a plurality of cylinders, as shown in  FIG. 5 . In another embodiment, the light directing device  5  includes an adjusting unit  61 , a first electrode  63 , a second electrode  65 , and a plurality of variable lenses  67  formed by a birefringence polar fluid, as shown in  FIG. 6 . The adjusting unit  61  adjusts a driver voltage from a driver source to the first electrode  63  and the second electrode  65 , thereby modulating an arrangement of the birefringence polar fluid of the plurality of the variable lenses  67 . As such, the direction of the image light beam is refracted to either a left or right eye of the viewer without wearing stereoscopic glasses. The birefringence polar fluid can be a liquid crystal element. In addition, the light directing device may further include an alignment layer (not shown) on the second electrode  65  to align the birefringence polar fluid of the variable lenses  67 . 
       FIG. 7  shows an image display of one embodiment of the disclosure. A light modulating module B is attached on a reflective display apparatus A including a display panel having a plurality of pixels. The reflective display can be an electrophoretic electronic ink display, a chlorestic liquid crystal display, or the likes. The light modulating module B includes a light source portion I and an image light modulating device such as a 3D barrier layer  7 . The light source portion I emits an illumination light beam  100  to be transmitted to the reflective display apparatus A and then reflected to generate an image light beam. A direction of the image light beam is then modulated by the 3D barrier layer  7  in a light path of the image light beam, such that the image light beam is then emitted to either a left or right eye of a viewer to form an auto stereoscopic image for the viewer after the image light beam passes through the 3D barrier layer  7 . The 3D barrier layer  7  has light shielding portions  7 A and light transmitting slits  7 B, as shown in  FIG. 7 . The positions of the light shielding portions  7 A and the light transmitting slits  7 B are fixed in  FIG. 7 . In another embodiment, the positions of the light shielding portions  8 A and the light transmitting slits  8 B of the 3D barrier layer  8  are variable, as shown in  FIG. 8 . The 3D barrier layer  8  includes a bottom electrode  81 , a top electrode  85 , and a liquid crystal layer  83  disposed therebetween. While a voltage is applied to the liquid crystal layer  83 , the light shielding portions  8 A and the light transmitting slits  8 B are formed. If the liquid crystal layer  83  is a bistable liquid crystal, the voltage can be re-zeroed to save energy after forming the light shielding portions  8 A and the light transmitting slits  8 B. In one embodiment, an additional polarizer layer  87  can be formed under the bottom electrode  81  and/or on the top electrode  85 . Note that the viewer watching the image display including the 3D barrier layer may watch auto stereoscopic images without wearing stereoscopic glasses. 
     In one embodiment, a light source portion is disposed on the image light modulating device (such as an angular adjustable reflective polarizing device  6  on a reflective polarizer  3 ), as shown in  FIG. 9 . The image light modulating device is disposed between the light source portion and the reflective display apparatus A. The reflective polarizer  3  is similar to that in embodiments of  FIGS. 1 and 2 , having a first portion and second portion of wires arranged in different directions or of different reflective polarizers. The angular adjustable reflective polarizing device  6  has a plurality of the switchable light modulating cells  60 . Each of the switchable light modulating cells  60  comprises a polarizer  67 , a first electrode  61 A, a second electrode  61 B, a compartment  63 , and a first and second light modulating media  65 A and  65 B filled in the compartment  63 . The first light and second light modulating media  65 A and  65 B are substantially immiscible and are of different refractive indices. The polarizer  67  is on a boundary between the first light and second light modulating media  65 A and  65 B and is capable of being adjusted with a variation of the boundary between the first light and second light modulating media  65 A and  65 B driven by voltage difference among the first and second electrodes  61 A and  61 B. Reference may be made to U.S. application Ser. Nos. 13/221,321 and 13/016,384 for the positions of the first and second electrode, the cross-sectional shape of the compartment  63 , and compositions of the first and second light modulating media  65 A and  65 B of  FIG. 9 , and are not limited thereto. The polarizer  67  can be a multilayer stack of alternating layers comprising a first material and a second material of different refractive indexes. The polarizer  67  reflects an image light beam (or an ambient light) having a first polarization state and substantially transmits an image light beam (or an ambient light) having a second polarization state. The first polarization state is different from the second polarization state. The reflected image light beam (having the first polarization state) will incident into another switchable light modulating cell  60 . The compartment  63  of the switchable light modulating cell  60  includes a partition wall  69  disposed between two adjacent switchable light modulating cell  60 . The light source portion  68  is disposed on the partition wall  69 . The light source portion  68  includes a light transparent window, wherein the light transparent window comprises a light transparent portion  66  and a frame  64 . The frame  64  includes an absorber  64 A and a reflection portion  64 B disposed between the absorber  64 A and the partition wall  69 . An ambient light  900  is capable of entering the switchable light modulating cell  60  by passing the light transparent portion  68  of the light transparent window. For a first set of switchable light modulating cell  60  (e.g. the rightmost one and the likes), the ambient light  900  having a second polarization state will travel through the polarizer  67  in the switchable light modulating cell  60  and the reflective polarizer  3  (the second portion) to enter and reflected by the reflective display apparatus A, thereby generating an image light beam. The image light beam having a second polarization state then travels through the reflective polarizer  3  (the second portion) and the polarizer  67  in the switchable light modulating cell  60  to enter either a left eye (or right eye) of a viewer wearing stereoscopic glasses. For the first set of switchable light modulating cells  60  (e.g. the leftmost one and the likes), the ambient light  900  having a first polarization state will be reflected by a polarizer  67  in the first set of the switchable light modulating cells  60 , and then travels through the partition wall  69  to a second set of switchable light modulating cells  60 . The reflected ambient light will travel through the reflective polarizer  3  (the first portion), and then enters and be reflected by the reflective display apparatus A corresponding to the second set of switchable light modulating cells  60 , thereby generating an image light beam having the first polarization state. The image light beam having the first polarization state is then travel through the reflective polarizer  3  (the first portion) and the polarizer  67  in the second set of switchable light modulating cells  60  to enter either a left eye (or right eye) of a viewer wearing stereoscopic glasses. For the second set of switchable light modulating cells  60  (e.g. the leftmost one and the likes), the ambient light  900  having a first polarization state will travel through the polarizer  67  in the switchable light modulating cell  60  and the reflective polarizer  3  (the first portion) to enter and be reflected by the reflective display apparatus A, thereby generating an image light beam. The image light beam having the first polarization state then travels through the reflective polarizer  3  (the first portion) and the polarizer  67  in the switchable light modulating cell  60  to enter either a left eye (or right eye) of a viewer wearing stereoscopic glasses. For the second set of switchable light modulating cells  60  (e.g. the leftmost one and the likes), the ambient light  900  having a second polarization state will be reflected by a polarizer  67  in the second set of switchable light modulating cells  60 , and then absorbed by the absorber  64 A (or reflected by the reflection portion  64 B to the first set of switchable light modulating cells  60 ). In this embodiment, no additional plane light source (such as a light emitting device and a light guide device) is disposed between the reflective display apparatus A and the image light modulating device. In other words, the ambient light  900  replaces the illumination light beam  100  in previously described embodiments. 
     In one embodiment, a light source portion is disposed on the image light modulating device (such as a micro electro mechanical system (MEMS) device  10  on a transparent substrate  101  on the reflective polarizer  3 ), as shown in  FIG. 10 . The micro electro mechanical system device  10  includes a moveable optical element  10 A and an actuator (not shown) to actuate the optical element  10 A. The moveable optical element  10 A is capable of being held at any one of a plurality of positions on the transparent substrate  101 . For example, the moveable optical element  10 A is a polarizer capable of substantially reflecting an image light beam (and an ambient light) having a first polarization state and substantially transmitting an image light beam (and an ambient light) having a second polarization state, wherein the first polarization state is different from the second polarization state. The motion (e.g. the polarizer position, the polarizer tilt angle, and the likes) of the polarizer is controlled by the actuator. The ambient light having a second polarization state will travel through the moveable optical element  10 A and the reflective polarizer  3  to enter and be reflected by the reflective display apparatus A, thereby generating an image light beam. The image light beam having a second polarization state then travels through the reflective polarizer  3  and the moveable optical element  10 A to enter either a left eye and right eye of a viewer wearing stereoscopic glasses. In this embodiment, no more plane light source (such as a light emitting device and a light guide device) is disposed between the reflective display apparatus A and the image light modulating device. In other words, the ambient light replaces the illumination light beam  100  in previously described embodiments. 
     Whether the light modulating module B includes, e.g. the light source portion I and the image light modulating device (such as a reflective polarizer  3 ) in  FIG. 1 , the light source portion I and the image light modulating device (such as a reflective polarizer  3  and a fractional wave plate  4  thereon) in  FIG. 3 , a light source portion I and an image light modulating device (such as a light directing device  5 ) in  FIGS. 5 and 6 , a light source portion I and an image light modulating device (such as a 3D barrier layer  7  or  8 ) in  FIGS. 7 and 8 , the light source portion on the image light modulating device (such as an angular adjustable reflective polarizing device  6  on a reflective polarizer  3 ) in  FIG. 9 , or the light source portion on the image light modulating device (such as the micro electro mechanical system (MEMS) device  10  on the transparent substrate  101  on the reflective polarizer  3 ) in  FIG. 10 , the light modulating module B is not fixed on the reflective display apparatus A. Note that the light modulating module B and the reflective display apparatus A can be separately made at different factories or even different countries, and then combined by a user to perform stereoscopic images. In addition, the reflective display apparatus A is input 3D image signals to display 3D images. The reflective display apparatus A cannot display 3D images by the input of 2D image signals, even if the light modulating module B is attached on the reflective display apparatus A. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.