Abstract:
A liquid crystal display apparatus comprises: a single transmissive-type liquid crystal panel having a display area partitioned between a first display area for producing an image on a front side and a second display area for producing an image on a rear side; a first illuminating unit for illuminating the first display area from the rear side; and a second illuminating unit for illuminating the second display area from the front side. With this configuration, the liquid crystal display apparatus is viewable from both the front and rear sides of the liquid crystal panel, and the thickness of the entire construction can be reduced.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from, and incorporates by reference the entire disclosure of, Japanese Patent Application No. 2007-277506, filed on Oct. 25, 2007. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a liquid crystal display apparatus and a portable phone incorporating the same, and more specifically to a liquid crystal display apparatus for use in a portable terminal and having a main display screen on the front side and a sub display screen on the rear side of a single liquid crystal panel, and a portable phone incorporating such a liquid crystal display apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]      FIG. 1  ( FIG. 1A  to  FIG. 1C ) is a diagram showing a portable phone mounted with a liquid crystal display apparatus according to the prior art, in which  FIG. 1A  shows a front view,  FIG. 1B  shows a side view, and  FIG. 1C  shows a rear view, and  FIG. 2  is a cross-sectional view taken along line  11 - 11  in  FIG. 1A , in which  FIG. 2A  shows a cross-sectional view of a main liquid crystal display and  FIG. 2B  shows a cross-sectional view of a sub liquid crystal display. In  FIG. 1 , F indicates the light-emitting direction of the main display, and R indicates the light-emitting direction of the sub display. The portable phone  10  shown in  FIG. 1  has a foldable structure such that the display part shown in the upper part of the figure can be folded over the operation part shown in the lower part, and the display part has two built-in displays, i.e., the main liquid crystal display  14  constructed by sandwiching a liquid crystal between front and rear two glass plates and the sub liquid crystal display  15  having a similar structure. The portable phone  10  further includes a receiver  16  and a microphone  17 . 
         [0006]    The liquid crystal display apparatus  20  of the portable phone according to the prior art comprises a main front polarizer  201 , a main liquid crystal  202 , a main rear polarizer  203 , a main rear reflector  204 , a main front display backlight guide  205 , a main front display light source  206  constructed from an LED, a main liquid crystal driver  207 , a sub rear display backlight guide  215 , a sub rear reflector  214 , a sub rear polarizer  213 , a sub liquid crystal  212 , a sub front polarizer  211 , a sub rear display light source  216 , and a sub liquid crystal driver  217 . 
         [0007]      FIG. 3  is a block diagram showing the circuit configuration of the portable phone according to the prior art. The portable phone  30  contains in its operation part a liquid crystal display controller  31  for controlling the main liquid crystal driver  207  of the main liquid crystal display  202  and the sub liquid crystal driver  217  of the sub liquid crystal display  212  and an illumination controller  32  for controlling the illumination of the front display light source  206  for the main display area  14  and the rear display light source  216  for the sub display area  15 . The illumination controller  32  is connected to the liquid crystal display controller  31  so as to be able to communicate with each other. Each light source is constructed from an LED. The operation part contains a cover open/close detection sensor  33  which is constructed, for example, from a magnetic sensor, and the display part contains a magnet in a position opposite of the magnetic sensor contained in the operation part. The cover open/close detection sensor  33  is connected to the liquid crystal display controller  31 . 
         [0008]    According to the prior art, the operation of the liquid crystal display and the display illumination of the portable phone are generally controlled in the following manner. When the cover open state is detected by the cover open/close detection sensor, the liquid crystal display controller  31  performs control to turn on the main display area  14  while turning off the sub display area  15 , and when the cover is closed, it performs control to turn on the sub display area  15  while turning off the main display area  14 . 
         [0009]    When the cover open state is detected by the cover open/close detection sensor, the illumination controller  32  performs control to turn on the front display light source  206  for a predetermined length of time or turn it on during an operation being performed and keep it on for a predetermined length of time after completion of the operation, while turning off the rear display light source  216 . On the other hand, when the cover is closed, the front display light source  206  is turned off, while turning on the rear display light source  216  for a predetermined length of time. 
         [0010]    When the cover is closed, control is performed to turn on the rear display light source  216  upon arrival of an incoming call. 
         [0011]    When the cover is open, control is performed to turn on the front display light source  206  upon arrival of an incoming call. 
         [0012]    As shown in  FIG. 1 , the prior art portable terminal has a foldable structure, and to display characters and image information, the display part of the portable terminal has a transmissive-type main liquid crystal panel on the front side and a transmissive-type sub liquid crystal panel on the rear side in a back-to-back arrangement, and information is displayed on the front and rear sides independently of each other. The portable terminal with the two liquid crystal panels mounted back-to-back in this manner becomes thicker than a portable terminal with a single liquid crystal panel, and this has been an obstacle in achieving a thin construction. 
         [0013]    As a solution to this problem, a design has been realized in which the display part of a portable terminal is constructed with a single liquid crystal panel and the housing of the display part is rotated to switch from one display to the other. However, this design involves problems such as increased cost, increased complexity, and difficulty in achieving a sturdy construction. As another solution, patent document 1 discloses a portable terminal in which the display part of the portable terminal is constructed with a single liquid crystal panel and is designed so as to be viewable from both the front and rear sides, while maintaining the thinness of the construction. 
         [0014]    The double-sided liquid crystal display apparatus used in the mobile communication terminal described in patent document 1 has a structure such that the display apparatus is partitioned between a first main display area and a second sub display area so that the single reflective-type liquid crystal panel can be viewed from both the front and rear sides thereof, wherein polarizers and reflectors are disposed symmetrically between the main display area and the sub display area. Then, as the folding cover is opened or closed, the opening or closing is detected and the display is switched from one area to the other to produce the display in the specified area. However, this liquid crystal display apparatus is limited to a reflective liquid crystal display of the type that uses a backlight. 
         [0015]    [Patent document 1] Japanese Unexamined Patent Publication No. 2001-27756 (refer to claim 1, paragraphs [0023] to [0027], and FIG. 3) 
       SUMMARY OF THE INVENTION 
       [0016]    The prior art has had the following disadvantages because two liquid crystal panels are combined as shown in the cross-sectional view of  FIG. 2 . 
         [0017]    (a) The construction of the entire display part becomes thick. 
         [0018]    (b) The weight increases because many circuit parts and component parts are used. 
         [0019]    (c) The cost increases because many circuit parts and component parts are used. 
         [0020]    (d) The structure of the liquid crystal display becomes complex, and sufficient strength to protect the liquid crystal display cannot be provided. 
         [0021]    Accordingly, it is an object of the present invention to provide a thin liquid crystal display apparatus that is constructed using a single transmissive-type liquid crystal panel and that is viewable from both the front and rear sides of the liquid crystal panel by arranging polarizers symmetrically while arranging a reflector in a partially asymmetrical fashion; it is another object of the invention to provide a portable phone equipped with such a liquid crystal display apparatus, achieving a thin and lightweight construction. 
         [0022]    A liquid crystal display apparatus according to the present invention, which achieves the above object, comprises: a single transmissive-type liquid crystal panel having a display area partitioned between a first display area for producing a display on a front side and a second display area for producing a display on a rear side; a first illuminating unit for illuminating the first display area from the rear side; and a second illuminating unit for illuminating the second display area from the front side. 
         [0023]    In the liquid crystal display apparatus, the first illuminating unit comprises a front display first backlight guide disposed on the rear side of the first display area of the liquid crystal panel and a first light source disposed adjacent to one end of the first backlight guide. 
         [0024]    In the liquid crystal display apparatus, the second illuminating unit comprises a rear display second backlight guide disposed on the front side of the second display area of the liquid crystal panel and a second light source disposed adjacent to one end of the second backlight guide. 
         [0025]    The liquid crystal display apparatus further comprises a liquid crystal driver, located on one side of the liquid crystal panel, for driving the liquid crystal panel to display information thereon, wherein the liquid crystal driver causes the first display area and the second display area to display information independently of each other. 
         [0026]    In the liquid crystal display apparatus, the second display area is formed within an edge portion of the liquid crystal panel along a longer side thereof. 
         [0027]    In the liquid crystal display apparatus, the second display area is formed within an edge portion of the liquid crystal panel along a shorter side thereof. 
         [0028]    In the liquid crystal display apparatus, the second display area includes a plurality of display areas. 
         [0029]    A portable phone according to the present invention, which achieves the above object, comprises a display part incorporating the above-described liquid crystal display apparatus and an operation part for operating the display part, the display part and the operation part being jointed together by a hinge in a foldable manner, wherein the second light source forming the second illuminating means is mounted inside a housing of the operation part at a position opposite the front side of the liquid crystal panel. 
         [0030]    The portable phone further comprises a liquid crystal display controller provided within the operation part and connected to the liquid crystal driver contained in the display part, wherein the liquid crystal display controller controls the liquid crystal driver so that the first display area and the second display area display information independently of each other. 
         [0031]    A portable phone according to the present invention, which achieves the above object, comprises a display part and an operation part for operating the display part, the display part and the operation part being jointed together by a hinge in a foldable manner and in such a manner so as to allow the display part to rotate at the hinge, wherein the above-described liquid crystal display apparatus is built into the display part. 
         [0032]    The liquid crystal display apparatus of the present invention provides the main and sub display areas using a single liquid crystal panel and controls the display and illumination for each individual display area, thereby making the liquid crystal panel viewable from both the front and rear sides thereof, while offering the advantage that the thickness of the liquid crystal display apparatus can be reduced by one half compared with the prior art. 
         [0033]    Since the sub display area only needs to display the communication and operation conditions with the portable phone folded up, the sub display area formed in an elongated shape can achieve a functional display without impairing the aesthetic design. 
         [0034]    Furthermore, since the liquid crystal driver and the illumination-related component parts for the sub liquid crystal panel can be eliminated, the parts cost can be reduced correspondingly. 
         [0035]    Moreover, the weight can be reduced by an amount equal to the weight of the sub liquid crystal panel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1A  is a front view showing a portable phone mounted with a liquid crystal display apparatus according to the prior art. 
           [0037]      FIG. 1B  is a side view showing a portable phone mounted with a liquid crystal display apparatus according to the prior art. 
           [0038]      FIG. 1C  is a rear view showing a portable phone mounted with a liquid crystal display apparatus according to the prior art. 
           [0039]      FIG. 2A  is a cross-sectional view of a main liquid crystal display taken along line  11 - 11 . 
           [0040]      FIG. 2B  is a cross-sectional view of a sub liquid crystal display taken along line  11 - 11 . 
           [0041]      FIG. 3  is a block diagram showing the circuit configuration of the portable phone according to the prior art. 
           [0042]      FIG. 4A  is a front view showing a portable phone mounted with a liquid crystal display apparatus according to the present invention. 
           [0043]      FIG. 4B  is a side view showing a portable phone mounted with a liquid crystal display apparatus according to the present invention. 
           [0044]      FIG. 4C  is a rear view showing a portable phone mounted with a liquid crystal display apparatus according to the present invention. 
           [0045]      FIG. 5A  is a cross-sectional view taken along line  41 - 41  in  FIG. 4 , showing the structure of the liquid crystal display apparatus mounted in the portable phone according to a first embodiment. 
           [0046]      FIG. 5B  is a cross-sectional view taken along line  41 - 41  in  FIG. 4 , showing the structure of the liquid crystal display apparatus mounted in the portable phone according to a second embodiment. 
           [0047]      FIG. 6  is a block diagram showing the circuit configuration of the portable phone according to the present invention. 
           [0048]      FIG. 7A  is a diagram showing a front view of a portable phone mounted with a liquid crystal display apparatus according to a third embodiment of the present invention. 
           [0049]      FIG. 7B  is a diagram showing a rear view of a portable phone mounted with a liquid crystal display apparatus according to a third embodiment of the present invention. 
           [0050]      FIG. 8A  is a diagram showing a front view of a portable phone mounted with a liquid crystal display apparatus according to a fourth embodiment of the present invention. 
           [0051]      FIG. 8B  is a diagram showing a rear view of a portable phone mounted with a liquid crystal display apparatus according to a fourth embodiment of the present invention. 
           [0052]      FIG. 9A  is a diagram showing a side view of a portable phone mounted with a liquid crystal display apparatus according to the prior art. 
           [0053]      FIG. 9B  is a diagram showing a rear view of a portable phone mounted with a liquid crystal display apparatus according to the prior art, with the display part not rotated. 
           [0054]      FIG. 9C  is a diagram showing a rear view of a portable phone mounted with a liquid crystal display apparatus according to the prior art, with the display part rotated. 
           [0055]      FIG. 10A  is a diagram showing a side view of a portable phone mounted with a liquid crystal display apparatus according to a fifth embodiment of the present invention. 
           [0056]      FIG. 10B  is a diagram showing a side view of a portable phone mounted with a liquid crystal display apparatus according to a fifth embodiment of the present invention, with the display part not rotated. 
           [0057]      FIG. 10C  is a diagram showing a side view of a portable phone mounted with a liquid crystal display apparatus according to a fifth embodiment of the present invention, with the display part rotated. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0058]    The embodiments of the present invention will be described below with reference to the accompanying drawings. 
         [0059]      FIG. 4  ( FIGS. 4A to 4C ) is a diagram showing a portable phone mounted with a liquid crystal display apparatus according to the present invention, in which  FIG. 4A  shows a front view,  FIG. 4B  shows a side view, and  FIG. 4C  shows a rear view. The portable phone  40  shown in  FIG. 4  has a foldable structure such that the display part shown in the upper part of the figure can be folded over the operation part shown in the lower part, and the display part contains a liquid crystal display apparatus  43  having a transmissive liquid crystal display panel constructed by sandwiching a liquid crystal between front and rear two glass plates. The liquid crystal display apparatus  43  is partitioned between a first main display area  44 , which produces a display viewable through a front-side main display window indicated by F in  FIG. 4B , and a second sub display area  45 , which produces a display viewable through a rear-side sub display window indicated by R. The portable phone  40  further includes a receiver  46  and a microphone  47 . According to the present invention, since the liquid crystal display apparatus  43  of the portable terminal  40 , viewable from both the front and rear sides, can be constructed from a single liquid crystal panel, the thickness of the portable terminal  40  is reduced by one-half compared with the portable terminal incorporating the prior art liquid crystal display apparatus requiring two liquid crystal panels. Next, the first and second embodiments of the liquid crystal display apparatus  43  will be described below with reference to  FIG. 5 . 
         [0060]      FIG. 5  is a cross-sectional view taken along line  41 - 41  in  FIG. 4 :  FIG. 5A  shows the structure of the liquid crystal display apparatus mounted in the portable phone according to the first embodiment, and  FIG. 5B  shows the structure of the liquid crystal display apparatus mounted in the portable phone according to the second embodiment. In  FIG. 5 , F indicates the light-emitting direction of the main display, and R indicates the light-emitting direction of the sub display. The liquid crystal display apparatus  50  of the portable phone according to the first embodiment comprises a front polarizer  501 , a liquid crystal  502 , a rear polarizer  503 , a rear reflector  504 , a front display backlight guide  505 , a front display light source  506  constructed from an LED, a liquid crystal driver  507 , a rear display backlight guide  508 , and a rear display light source  509 . To enhance the viewability of the main and sub displays, the front polarizer  501  and the rear polarizer  503  are arranged so as to cover the entire area of the liquid crystal  502 , as in the prior art, but the rear reflector  504  is not disposed in the sub display area, but disposed only in the main display area. 
         [0061]    The liquid crystal display apparatus  51  of the portable phone  40  according to the second embodiment comprises a front polarizer  501 , a liquid crystal  502 , a rear polarizer  503 , a rear reflector  504 , a front display backlight guide  505 , a front display light source  506  constructed from an LED, and a liquid crystal driver  507 . The rear display backlight guide  508  and the rear display light source  509  are mounted inside the housing of the operation part of the portable terminal so as to be positioned opposite the sub display area of the liquid crystal display apparatus  51 . 
         [0062]      FIG. 6  is a block diagram showing the circuit configuration of the portable phone according to the present invention. The portable phone  60  contains in its operation part a liquid crystal display controller  61  for controlling the liquid crystal driver  507  of the liquid crystal display apparatus  502  and an illumination controller  62  for controlling the illumination of the front display light source  506  for the main display area  44  and the rear display light source  509  for the sub display area  45 . The illumination controller  62  is connected to the liquid crystal display controller  61  so as to be able to communicate with each other. Each light source is constructed from an LED. The operation part contains a cover open/close detection sensor  63 , which is constructed, for example, from a magnetic sensor, and the display part contains a magnet in a position opposite the magnetic sensor contained in the operation part. The cover open/close detection sensor  63  is connected to the liquid crystal display controller  61 . 
         [0063]    The liquid crystal driver  507  is located on one side of the liquid crystal  502  and drives the liquid crystal  502  to display information. The liquid crystal driver  507  causes the first main display area  44  and the second sub display area  45  to display information independently of each other. 
         [0064]    The liquid crystal display controller  61  is provided within the operation part and connected to the liquid crystal driver  507  contained in the display part. The liquid crystal display controller  61  controls the liquid crystal driver  507  so that the first main display area  44  and the second sub display area  45  display information independently of each other. 
         [0065]    According to the present invention, the operation of the liquid crystal display and the display illumination of the portable phone are controlled in the following manner. The liquid crystal display controller  61  performs control based on a signal received from the cover open/close detection sensor  63 , i.e., when it is determined that the cover is opened, the main display area  44  is turned on, and when it is determined that the cover is closed, the main display area  44  is turned off. On the other hand, when it is determined that the cover is closed, control is performed to turn off the main display area  44 , while turning on the sub display area  45 . 
         [0066]    When the cover open state is detected by the cover open/close detection sensor, the illumination controller  62  performs control to turn on the front display light source  506  for a predetermined length of time or turn it on during an operation being performed and keep it on for a predetermined length of time after completion of the operation, while turning off the rear display light source  509 . On the other hand, when the cover is closed, the front display light source  506  is turned off, while turning on the rear display light source  509  for a predetermined length of time. 
         [0067]    When the cover is closed, control is performed to turn on the rear display light source  509  upon arrival of an incoming call. 
         [0068]    When the cover is open, control is performed to turn on the front display light source  506  upon arrival of an incoming call. 
         [0069]    Since the sub display area  45  is provided at a position far away from the liquid crystal driver  507  located on one side of the liquid crystal  502 , illumination from the front display light source  506  for the main display area  44  can be efficiently used, and the main display area  44  and the sub display area  45  can be formed using minimum required space and without wasting space. Switching between the front display light source  506  for the front display backlight guide  505  and the rear display light source  509  for the rear display backlight guide  508  should be made synchronously with the switching of the display between the main display area  44  and the sub display area  45  of the liquid crystal  502 . 
         [0070]      FIG. 7  is a diagram showing a portable phone mounted with a liquid crystal display apparatus according to a third embodiment of the present invention,  FIG. 7A  showing a front view and  FIG. 7B  a rear view. In the example shown, only one sub display window is provided along a longitudinal side of the display part. 
         [0071]      FIG. 8  is a diagram showing a portable phone mounted with a liquid crystal display apparatus according to a fourth embodiment of the present invention,  FIG. 8A  showing a front view and  FIG. 8B  a rear view. In the example shown, two sub display windows are provided along one longitudinal side of the display part. For example, a digital clock is displayed in the first sub display window, and a mark showing the remaining battery capacity is displayed in the second sub display window. 
         [0072]      FIG. 9  is a diagram showing a portable phone mounted with a liquid crystal display apparatus according to the prior art,  FIG. 9A  showing a side view,  FIG. 9B  a rear view with the display part not rotated, and  FIG. 9C  a rear view with the display part rotated. In the case of the portable phone having a rotating mechanism  91  such as shown in  FIG. 9 , if two liquid crystal displays are provided as shown in  FIG. 1 , the display viewable from the rear side cannot be presented as the sub liquid crystal display  15  is hidden behind the rotating mechanism  15 . 
         [0073]      FIG. 10  is a diagram showing a portable phone mounted with a liquid crystal display apparatus according to a fifth embodiment of the present invention,  FIG. 10A  showing a side view,  FIG. 10B  a rear view with the display part not rotated, and  FIG. 10C  a rear view with the display part rotated. In the portable phone  100  shown in  FIG. 10 , the display part incorporating the liquid crystal display apparatus  103  and the operation part for operating the display part are joined together by a hinge  102  in a foldable manner and in such a manner as to allow the display part to rotate at the hinge  102 . In the portable phone  100  according to the present invention, unlike the prior art portable phone shown in  FIG. 9 , the sub display area  105  is viewable from the rear side, since it is located at a position not hidden behind the rotating mechanism  101 , as shown in  FIG. 10 .