Liquid crystal display device with a plurality of projections having different heights and process for manufacturing the same

Abstract

A liquid crystal display device comprises a pair of substrates ( 1, 2 ) each having an electrode ( 13, 5 ), a liquid crystal layer held between the pair of substrates ( 1, 2 ) in which at least two kinds of projections ( 20, 21 ) having different projection heights are formed on one of the pair of substrates ( 1, 2 ) using the same material. These projections ( 20, 21 ) are obtained by the process comprising the steps, i.e., a resin film formation step of forming a projection resin film on the surface of one of the pair of substrates ( 1, 2 ) using photosensitive resin, and a projection formation step of simultaneously forming at least two types of projections ( 20, 21 ) having different projection heights on the substrate ( 2 ) using a photomask having variable transmittances and conducting exposure and development in such a manner that resulting thickness of the projection resin film can be varied. Thus, liquid crystal display devices comprising several kinds of projections having different heights accurately formed on the predetermined positions can be obtained.

1 - 2 . (canceled)  
   
   
       3 . A liquid crystal display device comprising: a pair of substrates each having an electrode; and a liquid crystal layer held between the pair of substrates, wherein at least two types of projections having different heights are formed on one of the pair of substrates using the same material, wherein the projections comprise a first projection and a second projection which is shorter than the first projection, wherein the first projection keeps a constant space between the pair of substrates and the second projection controls the orientation of the liquid crystal layer.  
   
   
       4 . The liquid crystal display device according to  claim 3 , wherein the first projection has a distribution density of 25/mm 2  or less.  
   
   
       5 . The liquid crystal display device according to  claim 3 , wherein the second projection has a distribution density of 1/dot or greater.  
   
   
       6 - 8 . (canceled)  
   
   
       9 . A liquid crystal display device comprising: a pair of substrates each having an electrode; and a liquid crystal layer held between the pair of substrates, wherein at least two types of projections having different heights are formed on one of the pair of substrates using the same material, wherein the projections comprise a first projection and a second projection which is shorter than the first projection, wherein the first projection controls the orientation of the liquid crystal layer and the second projection forms asperities on the electrode to diffuse the reflected light.  
   
   
       10 . The liquid crystal display device according to  claim 9 , wherein the first projection has a distribution density of 1/dot or greater.  
   
   
       11 . The liquid crystal display device according to  claim 9 , wherein the second projection has a distribution density of 400/mm 2  or greater.  
   
   
       12 . A liquid crystal display device comprising: a pair of substrates each having an electrode; and a liquid crystal layer held between the pair of substrates, wherein at least two types of projections having different heights are formed on one of the pair of substrates using the same material, wherein the projections comprise a first projection, a second projection which is shorter than the first projection, and a third projection which is shorter than the second projection, wherein the first projection maintains a constant space between the pair of substrates, the second projection controls the orientation of the liquid crystal layer and the third projection forms asperities on the electrode to diffuse the reflected light.  
   
   
       13 . The liquid crystal display device according to  claim 12 , wherein the first projection has a distribution density of 25/mm 2  or less.  
   
   
       14 . The liquid crystal display device according to  claim 12 , wherein the second projection has a distribution density of 1/dot or greater.  
   
   
       15 . The liquid crystal display device according to  claim 12 , wherein the third projection has a distribution density of 400/mm 2  or greater.  
   
   
       16 . A liquid crystal display device comprising: a pair of substrates each having an electrode: and a liquid crystal layer held between the pair of substrates, wherein at least two types of projections having different heights are formed on one of the pair of substrates using the same material, wherein the projections are made of photosensitive resin.  
   
   
       17 . A liquid crystal display device comprising: a pair of substrates each having an electrode; and a liquid crystal layer held between the pair of substrates, wherein at least two types of projections having different heights are formed on one of the pair of substrates using the same material, wherein the projections are made of a metal material.  
   
   
       18 . A liquid crystal display device comprising: a pair of substrates each having an electrode; and a liquid crystal layer held between the pair of substrates, wherein at least two types of projections having different heights are formed on one of the pair of substrates using the same material, wherein at least one type of the projections has a trapezoidal profile.  
   
   
       19 . A liquid crystal display device comprising: a pair of substrates each having an electrode; and a liquid crystal layer held between the pair of substrates, wherein at least two types of projections having different heights are formed on one of the pair of substrates using the same material, wherein the liquid crystal display device is of the OCB mode or the VA mode.  
   
   
       20 . A method for manufacturing a liquid crystal display device having a liquid crystal layer held between a first substrate and a second substrate comprising: 
 a resin film formation step of forming a projection resin film made of photosensitive resin on the first substrate;    a projection formation step of simultaneously forming at least two types of projections having different heights on the first substrate using a photomask having variable transmittances and conducting exposure and development in such a manner that the resulting thickness of the projection resin film can be varied; and    a liquid crystal inserting step of filling the space between the first substrate and the second substrate with liquid crystal after attaching the first substrate and the second substrate to each other with the projection side of the first substrate facing the second substrate.    
   
   
       21 . The method for manufacturing a liquid crystal display device according to  claim 20  further comprising a step of forming an electrode on the first substrate prior to the resin film formation step.  
   
   
       22 . A method for manufacturing a liquid crystal display device having a liquid crystal layer held between a first substrate and a second substrate comprising: 
 a resin film formation step of forming a projection resin film made of photosensitive resin on the first substrate;    a projection formation step of simultaneously forming at least two types of projections having different heights on the first substrate using a photomask having variable transmittances and conducting exposure and development in such a manner that the resulting thickness of the projection resin film can be varied; and    a liquid crystal inserting step of applying liquid crystal to the surface of one of the first and the second substrate, and attaching the first substrate to the second substrate.    
   
   
       23 . The method for manufacturing a liquid crystal display device according to  claim 22  further comprising a step of forming an electrode on the first substrate before the resin film formation step.  
   
   
       24 . A method for manufacturing a liquid crystal display device having a liquid crystal layer held between a first substrate and a second substrate comprising: 
 a projection formation step of simultaneously forming at least two types of projections having different heights on the first substrate by repeatedly depositing photosensitive resin, exposing and developing in a manner such that the projection color layers have different distribution patterns in their layer conditions; and    a liquid crystal inserting step of filling the space between the first substrate and the second substrate with liquid crystal after attaching the first substrate and the second substrate to each other with the projection side of the first substrate facing the second substrate.    
   
   
       25 . The method for manufacturing a liquid crystal display device according to  claim 24  further comprising a step of forming an electrode on the first substrate prior to the projection formation step.  
   
   
       26 . A method for manufacturing a liquid crystal display device having a liquid crystal layer held between a first substrate and a second substrate comprising: 
 a projection formation step of simultaneously forming at least two types of projections having different heights on the first substrate by repeatedly depositing photosensitive resin, exposing and developing in a manner such that the projection color layers have different distribution patterns in their layer conditions; and    a liquid crystal inserting step of applying liquid crystal to the surface of one of the first substrate and the second substrate and attaching the first substrate to the second substrate.    
   
   
       27 . The method for manufacturing a liquid crystal display device according to  claim 26  further comprising a step of forming an electrode on the first substrate prior to the projection formation step.  
   
   
       28 . The method for manufacturing a liquid crystal display device according to  claim 20  or  22  further comprising: 
 a step of forming a display color layer by depositing photosensitive resin on one of the first substrate and the second substrate, exposing and developing; and    a step of forming an electrode made of a transparent conductive film on the surface of the display color layer,    characterized in that the projection resin film is formed on the surface of the electrode.    
   
   
       29 . The method for manufacturing a liquid crystal display device according to  claim 24  or  26  further comprising: 
 a step of forming a display color layer by depositing photosensitive resin on one of the first substrate and the second substrate, exposing and developing; and    a step of forming an electrode made of a transparent conductive film on the surface of the display color layer,    characterized in that the projection color film is formed on the surface of the electrode.    
   
   
       30 . The method for manufacturing a liquid crystal display device according to  claim 29 , wherein the display color layer and the projection color layer are made of the same kind of resin material.  
   
   
       31 . The method for manufacturing a liquid crystal display device according to  claim 20  or  22 , wherein the resin film formation step comprises after arranging source wirings and gate wirings on one of the first substrate and the second substrate in a manner such that the source wirings and the gate wirings intersect at approximately right angles and forming switching elements nearby each intersection of the source wirings and the gate wirings, forming the projection resin film, 
 wherein, after the projection formation step, electrodes are selectively formed on the projection side surface in a manner such that at least the highest projection protrudes from the electrodes.    
   
   
       32 . The method for manufacturing a liquid crystal display device according to  claim 24  or  26 , wherein the projection formation step comprises, after arranging source wirings and gate wirings on one of the first substrate and the second substrate in a manner such that the source wirings and the gate wirings intersect at approximately right angles and forming switching elements nearby each intersection of the source wirings and the gate wirings, forming the projection color layer, 
 wherein, after the projection formation step, electrodes are selectively formed on the projection side surface in a manner such that at least the highest projection protrudes from the electrodes.    
   
   
       33 . The method for manufacturing a liquid crystal display device according to  claim 31 , wherein by covering at least the shortest projection with the electrode, asperities are formed on the electrode to diffuse the reflected light.  
   
   
       34 . The method for manufacturing a liquid crystal display device according to  claim 32 , wherein by covering at least the shortest projection with the electrode, asperities are formed on the electrode to diffuse the reflected light.