Abstract:
A light-reflection type liquid crystal display device includes (a) a liquid crystal display panel, (b) a polarizer mounted on the liquid crystal display panel, (c) a light-guide mounted on the polarizer, (d) a resin layer sandwiched between the polarizer and the light-guide for fixing the polarizer and the light-guide to each other, (e) a light-source arranged adjacent to an end of the light-guide for supplying light to the light-guide, and (D a frame having a bottom and a wall defining an opening which has the same contour as that of the light-guide. The light-guide is positioned relative to the polarizer by being lowered along an inner wall of the frame through the opening onto the polarizer.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a liquid crystal display device and a method of fabricating the same, and more particularly to a light-reflection type liquid crystal display device and a method of fabricating the same  
           [0003]    2. Description of the Related Art  
           [0004]    Since a portable terminal device such as a portable computer can accumulate power in limited amount, parts constituting a portable terminal device are required to consume small power. Accordingly, not a display unit which can emit light by itself, but a liquid crystal display device which consumes small power is predominantly used as a display unit for a portable terminal device.  
           [0005]    However, a liquid crystal display device does not have a function of emitting light by itself, and hence, has to include a light source. In accordance with a light-source, a liquid crystal display device is grouped into a light-reflection type liquid crystal display device, a light-transmission type liquid crystal display device, and a combination type liquid crystal display device.  
           [0006]    A light-transmission type liquid crystal display device has a back-light source by which the device can display images.  
           [0007]    A light-reflection type liquid crystal display device includes a light-reflector therein, and uses light entering into the device and reflecting at the light-reflector, as a light source. Hence, a light-reflection type liquid crystal display device is not necessary to include a back-light source unlike a light-transmission type liquid crystal display device.  
           [0008]    A combination type liquid crystal display device includes a first section fabricated as a light-transmission type liquid crystal display device and a second section fabricated as a light-reflection type liquid crystal display device.  
           [0009]    A light-reflection type liquid crystal display device consumes smaller power and can be fabricated thinner and lighter than a light-transmission type liquid crystal display device, and hence, is mainly used as a display unit for a portable terminal device. This is because a light-reflection type liquid crystal display device uses light entering thereinto and reflecting at a light-reflector for displaying images, and hence, is necessary to have a back-light source unlike a light-transmission type liquid crystal display device.  
           [0010]    However, since a light-reflection type liquid crystal display device uses external light as a light source, it is difficult or almost impossible for a user to clearly see displayed images, if it is dark around the device.  
           [0011]    In order to solve such a problem, a light-reflection type liquid crystal display device designed to include a preliminary light source which supplies light to the device through a light-guide has been suggested, for instance, in Japanese Patent No. 2699853 (Japanese Patent Application Publication No. 7-199184), and Japanese Patent Application Publications Nos. 11-149252, 11-219610 and 2000-147499.  
           [0012]    [0012]FIG. 1 is a cross-sectional view of an example of a conventional light-reflection type liquid crystal display device including a preliminary light source.  
           [0013]    A light-reflection type liquid crystal display device  100  illustrated in FIG. 1 is comprised of a liquid crystal display panel  101 , a polarizer  102  lying on the liquid crystal display panel  101  in such a direction as facing a viewer, a light-guide  103  mounted on the polarizer  102 , a resin layer  104  sandwiched between the polarizer  102  and the light-guide  103  for fixing them to each other, and a light source  105  located adjacent to an end of the light-guide  103 , and supplying light to the liquid crystal display panel  101  through the light-guide  103 . Though not illustrated, the light source  105  is usually surrounded by a cover (see FIG. 4C).  
           [0014]    Light emitted from the light source  105  reaches the polarizer  102  through the light-guide  103 , is polarized when passing through the polarizer  102 , and reaches the liquid crystal display panel  101  to thereby be used for displaying images.  
           [0015]    [0015]FIGS. 2A to  2 D are cross-sectional views of the light-reflection type liquid crystal display device  100  illustrated in FIG. 1, illustrating respective steps of a method of fabricating the same.  
           [0016]    First, as illustrated in FIG. 2A, the polarizer  102  is mounted on the liquid crystal display panel  101 , and then, liquid acrylic resin  104  which will be hardened when ultra-violet ray is irradiated thereto is dropped onto the polarizer  102 .  
           [0017]    Then, as illustrated in FIG. 2B, the light-guide  103  is mounted onto the polarizer  102 . The resin  104  spreads wholly on the polarizer  102  due to a weight of the light-guide  103 .  
           [0018]    While the resin  104  is being extended, the light-guide  103  is positioned relative to the liquid crystal display panel  101 , as illustrated in FIG. 2C.  
           [0019]    Then, as illustrated in FIG. 2D, ultra-violet (UV) ray from which short-wave ultra-violet is cut is irradiated to the resin  104  through a glass filter  106  to thereby harden the resin  104 .  
           [0020]    Thus, the light-reflection type liquid crystal display device  100  illustrated in FIG. 1 is completed.  
           [0021]    However, the above-mentioned method of fabricating the light-reflection type liquid crystal display device  100  is accompanied with the following problems.  
           [0022]    The first problem is that a relative position and/or angle between the liquid crystal display panel  101  and the light-guide  103  is deviated from a desired position or angle while the resin  104  is being extended.  
           [0023]    As a result, it is necessary to adjust the relative position before ultra-violet ray is irradiated to the resin  104 , causing an increase in the number of fabrication steps and a time necessary for fabricating the liquid crystal display device  100 .  
           [0024]    The second problem is that, as illustrated in FIG. 3, the resin  104  often spreads beyond the polarizer  102  and covers the liquid crystal display panel  101  therewith.  
           [0025]    The light-guide  103  and the polarizer  102  are generally composed of plastic. The resin  104  is selected among resin having a linear expansion coefficient close to that of the light-guide  103  and the polarizer  102 , for instance, a linear expansion coefficient in the range of 3×10 −5  to 7×10 −5 /degree. However, if the resin  104  spreads onto the liquid crystal display panel  101  as illustrated in FIG. 3, the resin  104  might be deformed at high or low temperature due to a difference in a linear expansion coefficient between the resin  104  and the liquid crystal display panel  101  composed of glass having a linear expansion coefficient of 5×10 −6 /degree. As a result, the resin  104  might be peeled off at a portion at which the resin  104  is deformed.  
         SUMMARY OF THE INVENTION  
         [0026]    In view of the above-mentioned problems in the conventional light-reflection type liquid crystal display device, it is an object of the present invention to provide a light-reflection type liquid crystal display device and a method of fabricating the same both of which are capable of preventing deviation in a relative position and/or angle between a liquid crystal display panel and a light-guide, or preventing a resin from being peeled off.  
           [0027]    In one aspect of the present invention, there is provided a method of fabricating a light-reflection type liquid crystal display device including at least a liquid crystal display panel, a polarizer lying on the liquid crystal display panel, a light-guide lying on the polarizer, and a resin layer sandwiched between the polarizer and the light-guide for fixing the polarizer and the light-guide to each other, including the steps of (a) fixing the liquid crystal display panel on which the polarizer is mounted, onto a bottom of a frame having an opening which has the same contour as that of the light-guide, (b) dropping resin onto the polarizer, (c) lowering the light-guide along an inner wall of the frame through the opening onto the polarizer, and (d) hardening the resin.  
           [0028]    In another aspect of the present invention, there is provided a light-reflection type liquid crystal display device including (a) a liquid crystal display panel, (b) a polarizer mounted on the liquid crystal display panel, (c) a light-guide mounted on the polarizer, (d) a resin layer sandwiched between the polarizer and the light-guide for fixing the polarizer and the light-guide to each other, (e) a light-source arranged adjacent to an end of the light-guide for supplying light to the light-guide, and (f) a frame having a bottom and a wall defining an opening which has the same contour as that of the light-guide, the light-guide being positioned relative to the polarizer by being lowered along an inner wall of the frame through the opening onto the polarizer.  
           [0029]    It is preferable that the opening is larger than a contour of the light-guide by a predetermined length, in which case, the predetermined length may be equal to a tolerance allowable when the liquid crystal display panel and the light-guide are positioned relative to each other.  
           [0030]    For instance, the liquid crystal display panel may be comprised of two substrates adhered to each other through adhesive, in which case, it is preferable that the frame is formed at a bottom thereof with an opening, and an inner edge of the opening is located more outwardly than the adhesive.  
           [0031]    There is further provided that a light-reflection type liquid crystal display device including (a) a liquid crystal display panel, (b) a polarizer mounted on the liquid crystal display panel, (c) a light-guide mounted on the polarizer, (d) a resin layer sandwiched between the polarizer and the light-guide for fixing the polarizer and the light-guide to each other, (e) a light-source arranged adjacent to an end of the light-guide for supplying light to the light-guide, and (f) a frame having a bottom and a wall defining an opening which has the same contour as that of the light-guide, the polarizer having an edge extending outwardly beyond an edge of the light-guide, the wall of the frame having an outwardly projecting portion such that the polarizer can be accommodated in the frame, the light-guide being positioned relative to the polarizer by being lowered along an inner wall of the frame through the opening onto the polarizer.  
           [0032]    There is still further provided a light-reflection type liquid crystal display device including (a) a liquid crystal display panel, (b) a polarizer mounted on the liquid crystal display panel, (c) a light-guide mounted on the polarizer, (d) a resin layer sandwiched between the polarizer and the light-guide for fixing the polarizer and the light-guide to each other, and (e) a light-source arranged adjacent to an end of the light-guide for supplying light to the light-guide, the polarizer having an edge extending outwardly beyond an edge of the light-guide.  
           [0033]    It is preferable that the light-guide has a non-light-guide area along an outer edge thereof.  
           [0034]    There is yet further provided a light-reflection type liquid crystal display device including (a) a liquid crystal display panel, (b) a polarizer mounted on the liquid crystal display panel, (c) a light-guide mounted on the polarizer, (d) a resin layer sandwiched between the polarizer and the light-guide for fixing the polarizer and the light-guide to each other, and (e) a light-source arranged adjacent to an end of the light-guide for supplying light to the light-guide, the polarizer having an edge extending outwardly beyond an edge of the liquid crystal display panel.  
           [0035]    The advantages obtained by the aforementioned present invention will be described hereinbelow.  
           [0036]    The present invention makes it possible to prevent a relative position and/or angle between a liquid crystal display panel and a light-guide from being deviated before a resin is hardened. Thus, it is no longer necessary to adjust the relative position and/or angle before ultra-violet ray is irradiated to a resin, preventing an increase in the number of fabrication steps and a time necessary for fabricating a liquid crystal display device.  
           [0037]    In addition, the present invention makes it possible to prevent a resin from extending beyond a polarizer to a liquid crystal display panel while the resin is being extended, and hence, prevent the hardened resin from being peeled off.  
           [0038]    The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]    [0039]FIG. 1 is a cross-sectional view of a conventional light-reflection type liquid crystal display device.  
         [0040]    [0040]FIGS. 2A to  2 D are cross-sectional views of the light-reflection type liquid crystal display device illustrated in FIG. 1, showing respective steps of fabricating the same.  
         [0041]    [0041]FIG. 3 is a partially enlarged cross-sectional view of the light-reflection type liquid crystal display device illustrated in FIG. 1.  
         [0042]    [0042]FIGS. 4A to  4 C are cross-sectional views of a light-reflection type liquid crystal display device in accordance with the first embodiment, showing respective steps in a method of fabricating the same.  
         [0043]    [0043]FIG. 5 is a cross-sectional view of a first variant of the light-reflection type liquid crystal display in accordance with the first embodiment.  
         [0044]    [0044]FIG. 6 is a cross-sectional view of a second variant of the light-reflection type liquid crystal display in accordance with the first embodiment.  
         [0045]    [0045]FIG. 7 is a partial cross-sectional view of a light-reflection type liquid crystal display in accordance with the second embodiment.  
         [0046]    [0046]FIG. 8 is a partial cross-sectional view of a conventional light-reflection type liquid crystal display.  
         [0047]    [0047]FIG. 9 is a partial cross-sectional view of the light-reflection type liquid crystal display in accordance with the second embodiment.  
         [0048]    [0048]FIG. 10 is a cross-sectional view of the light-reflection type liquid crystal display in accordance with the second embodiment.  
         [0049]    [0049]FIG. 11 illustrates how a liquid crystal display panel is accommodated into a frame in the light-reflection type liquid crystal display in accordance with the second embodiment. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0050]    Preferred embodiments in accordance with the present invention will be explained hereinbelow with reference to drawings.  
         [0051]    [First Embodiment] 
         [0052]    [0052]FIGS. 4A to  4 C are cross-sectional views of a light-reflection type liquid crystal display device in accordance with the first embodiment, showing respective steps in a method of fabricating the same.  
         [0053]    In the method, a frame  10  illustrated in FIG. 4A is used.  
         [0054]    The frame  10  is comprised of a bottom  10   a  and a wall  10   b  standing perpendicularly upwardly from an outer edge of the bottom  10   a . The wall  10   b  defines an opening  10   c  which is the same as or at least similar to a contour of the light-guide  103 . The frame  10  is composed of plastic. As an alternative, the frame  10  may be composed of metal such as aluminum.  
         [0055]    The light-reflection type liquid crystal display device in accordance with the first embodiment is fabricated as follows through the use of the frame  10 .  
         [0056]    First, the polarizer  102  is fixed onto the liquid crystal display panel  101 . Then, as illustrated in FIG. 4A, the liquid crystal display panel  101  is fixed onto the bottom  10   a  of the frame  10 , for instance, through adhesive or a double-sided adhesive tape. A position of the liquid crystal display panel  101  relative to the bottom  10   a  is determined taking a relative position between the liquid crystal display panel  101  and the light-guide  103  into consideration.  
         [0057]    Then, as illustrated in FIG. 4B, the resin  104  composed of liquid acrylic resin which is hardened on irradiation of ultra-violet ray thereto is dropped onto the polarizer  102 .  
         [0058]    Then, as illustrated in FIG. 4C, the light-guide  103  is lowered downwardly along an inner wall of the wall  10   b  through the opening  10   c  towards the polarizer  102 , and mounted on the polarizer  102 .  
         [0059]    After the resin  104  has been extended over the polarizer  102  due to a weight of the light-guide  103 , ultra-violet ray is irradiated to the resin  104  through a glass filter  106  (not illustrated in FIG. 4C, but see FIG. 2D) for hardening the resin  104 .  
         [0060]    In accordance with the first embodiment, the resin  104  spreads and is hardened with the light-guide  103  is kept positioned relative to the liquid crystal display panel  101 . In the conventional method, a relative position and/or angle between the liquid crystal display panel  101  and the light-guide  103  might be deviated while the resin  104  is being extended. In contrast, the light-guide  103  is kept positioned relative to the liquid crystal display panel  101  in the first embodiment, and hence, a relative position and/or angle between them is not deviated. As a result, the method in accordance with the first embodiment enhances a yield in fabrication of a light-reflection type liquid crystal display device.  
         [0061]    The frame  10  is not to be limited to such a structure as illustrated in FIG. 4A. It should be noted that the frame  10  may have modified structures as follows.  
         [0062]    [0062]FIG. 5 is a cross-sectional view of a frame  11  as a first variant of the frame  10 .  
         [0063]    The frame  11  is designed to have the opening  10   c  larger than a contour of the light-guide  103  by a predetermined length L.  
         [0064]    For instance, if the liquid crystal display panel  101  is rectangular in size of 80 mm×60 mm, a positional tolerance between the liquid crystal display panel  101  and the light-guide  103  is about 0.5 mm, in which case, the predetermined length L may be equal to 0.5 mm.  
         [0065]    [0065]FIG. 5 is a cross-sectional view of a frame  12  as a second variant of the frame  10 .  
         [0066]    The liquid crystal display panel  101  is comprised of two substrates  101   a  and  101   b  adhered to each other through adhesive tapes  101   c.    
         [0067]    The frame  102  is formed at the bottom  10   a  thereof centrally with a rectangular opening  12   a  such that an edge of the opening  12   a  is located more outwardly than the adhesive tapes  101   c.    
         [0068]    An operation panel (not illustrated) is arranged above the light-guide  103 . A plurality of keys is arranged on the operation panel, and a user can operate the light-reflection type liquid crystal display device by actuating any key or keys. However, if oscillation generated when a user actuate a key is transferred to the liquid crystal display panel  101 , a defectiveness may be caused in displaying images.  
         [0069]    By forming the frame  12  at the bottom  10   a  thereof with the opening  12   a , such oscillation is unlikely to be transferred to the liquid crystal display panel  101 , ensuring reduction in the defectiveness.  
         [0070]    [Second Embodiment] 
         [0071]    [0071]FIG. 7 is a partial cross-sectional view of a light-reflection type liquid crystal display device  20  in accordance with the second embodiment.  
         [0072]    The polarizer  102  in the light-reflection type liquid crystal display device  20  is designed to have an edge  102   a  extending outwardly beyond an edge  103   a  of the light-guide  103 .  
         [0073]    As illustrated in FIG. 3, the conventional light-reflection type liquid crystal display device is accompanied with a problem that the resin  104  spreads beyond the polarizer  102  to the liquid crystal display panel  101 , in which case, the resin  104  might be deformed at high or low temperature due to a difference in a linear expansion coefficient between the resin  104  and the liquid crystal display panel  101  composed of glass. As a result, the resin  104  might be peeled off at a portion at which the resin  104  is deformed.  
         [0074]    In the light-reflection type liquid crystal display device  20  in accordance with the second embodiment, since the polarizer  102  has an edge  102   a  extending outwardly beyond an edge  103   a  of the light-guide  103 , it is possible to prevent the resin  104  from spreading to the liquid crystal display panel  101 , as illustrated in FIG. 7.  
         [0075]    As a result, it is possible to prevent the resin  104  from being deformed due to a difference in a linear expansion coefficient between the resin  104  and the liquid crystal display panel  101 , and hence, it is further possible to prevent the resin  104  from being peeled off at a portion at which the resin  104  is deformed.  
         [0076]    In addition, since the resin  104  does not make contact with the liquid crystal display panel  101 , if defectiveness is found in the liquid crystal display panel  101 , for instance, it would be possible to peel the polarizer  102  off the liquid crystal display panel  101  and repair the liquid crystal display panel  101 .  
         [0077]    Instead of designing the polarizer  102  to have an edge  102   a  extending outwardly beyond an edge  103   a  of the light-guide  103 , the polarizer  102  may be designed to have an edge  102   a  extending outwardly beyond an edge  101   a  of the liquid crystal display panel  101 . By so designing the polarizer  102 , it would be possible to prevent the resin  104  from spreading over the liquid crystal display panel  101 .  
         [0078]    Even if the polarizer  102  is designed to have an edge  102   a  extending outwardly beyond an edge  103   a  of the light-guide  103 , as illustrated in FIG. 8, the resin  104  might pour out of a gap between the polarizer  102  and the light-guide  103 , and rise up to cover the light-guide  103  therewith, if the resin  104  is dropped onto the polarizer  102  in too excessive amount. If the resin  104  covers the light-guide  103  therewith, the light-guide  103  would loose its light-guiding function at a portion covered with the resin  104 .  
         [0079]    In order to avoid such a problem, as illustrated in FIG. 9, it is preferable that the light-guide  103  has a non-light-guiding area  103   a  at its outer marginal area.  
         [0080]    Among an area of the light-guide  103 , a light-guide area  103   b  through which light is actually guided is formed generally as a prism. Hence, the non-light-guiding area  103   a  may be formed to be a planar area in contrast with the prism-shaped light-guide area  103   b.    
         [0081]    [0081]FIG. 10 is a cross-sectional view of a frame  13  used in a method of fabricating the light-reflection type liquid crystal display device  20  in accordance with the second embodiment.  
         [0082]    The polarizer  102  in the second embodiment is designed to have the edge  102   a  extending outwardly beyond the edge  103   a  of the light-guide  103 . Accordingly, if the frame  10  used in the first embodiment is used also for the light-reflection type liquid crystal display device  20 , the polarizer  102  would interfere with the wall  10   b  of the wall  10 .  
         [0083]    Hence, as illustrated in FIG. 10, the frame  13  is formed at a wall  13   b  thereof with an outwardly projecting portion  13   c  such that the edge  102   a  of the polarizer  102  is in level with the outwardly projecting portion  13   c  when the polarizer  102  is accommodated in the frame  13 . Thus, the polarizer  102  together with the liquid crystal display panel  101  can be accommodated into the frame  103 , even if the polarizer  102  has the edge  102   a  extending outwardly beyond the edge  103   a  of the light-guide  103 .  
         [0084]    When the polarizer  102  together with the liquid crystal display panel  101  is accommodated into the frame  103 , as illustrated in FIG. 11, the liquid crystal display panel  101  is inclined, and then, the polarizer  102  is first accommodated at the edge  102   a  into the outwardly projecting portion  13   c . Then, the liquid crystal display panel  101  is wholly laid onto the bottom  10   a  of the frame  13 .  
         [0085]    Since the frame  13  is designed to have the outwardly projecting portion  13   c , the opening  10   c  is defined by a portion  13   d  of the wall  13   b  located above the outwardly projecting portion  13   c.    
         [0086]    While the present invention has been described in connection with certain preferred embodiments, it is to be understood that the subject matter encompassed by way of the present invention is not to be limited to those specific embodiments. On the contrary, it is intended for the subject matter of the invention to include all alternatives, modifications and equivalents as can be included within the spirit and scope of the following claims.  
         [0087]    The entire disclosure of Japanese Patent Application No. 2002-157419 filed on May 30, 2002 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.