Abstract:
The present invention relates to a display device comprising a substrate, a display module, a lenticular lens and a glass cap. The display module is attached to the substrate and is used for emitting light. The lenticular lens is disposed above the display module and is used for changing the luminous intensity distribution of the light emitted by the display module. The glass cap is disposed above the lenticular lens and is sealed with the substrate for capping the lenticular lens and the display module. According to the display device of the invention, the disunity of the luminous intensity distribution of the light emitted by the display module in different view angles is improved, which facilitates the color control. The present invention also relates to a method of making a display device with a lenticular lens.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a display device, especially to a display device having a lenticular lens therein.  
         [0003]     2. Description of the Related Art  
         [0004]     Referring to  FIG. 1 , a cross-sectional view of a conventional organic light emitting diode is shown. The conventional organic light emitting diode  10  comprises a capping  11 , a cathode  12 , an electron-injecting layer (EIL)  13 , an electron-transporting layer (ETL)  14 , a hole-blocking layer (HBL)  15 , an emission layer (EML)  16 , a hole-transporting layer (HTL)  17 , a hole-injecting layer (HIL)  18  and an anode  19 .  
         [0005]     Referring to  FIG. 2 , a schematic illustration of light transportation of the conventional organic light emitting diode of  FIG. 1  is shown. In the conventional organic light emitting diode  10 , light goes through many different materials. This makes each of the three primary-color lights, namely, red light, green light and blue light, have a different luminous intensity distribution in different view angles due to the interference effect. For example, light emitted from the emission layer (EML)  16  will radiate upwardly or downwardly, wherein the light that radiates downwardly goes through the hole-transporting layer (HTL)  17  and hole-injecting layer (HIL)  18 , is reflected by the anode  19 , then interferes with the light that radiates upwardly. As a result, each of the three primary-color lights has a different luminous intensity distribution in different view angles, and the mixture of colors will cause the color shift effect on display.  
         [0006]     Referring to  FIG. 3 , a cross-sectional view of a conventional organic light emitting diode display device is shown. The conventional display device  20  comprises a substrate  21 , a display module  22  and a glass cap  23 . The display module  22  is attached to the upper surface of the substrate  21  and is an organic light emitting diode adapted for emitting light. The light emitted from the display module  22  includes three primary-color lights, namely, red light, green light and blue light. The glass cap  23  is disposed above the display module  22  and sealed with the substrate  21  by sealant  24  for capping the display module  22  to form a package structure.  
         [0007]     Referring to  FIG. 4 , luminous intensity distributions of the three primary-color lights emitted from a conventional organic light emitting diode display device  20  observed in different view angles are shown, wherein zero degree represents that the observation is at the vertical direction, the positive degree represents that the observation is at the right side of the vertical direction, and the negative degree represents that the observation is at the left side of the vertical direction. The disadvantage of the conventional organic light emitting diode display device  20  is that the three primary-color lights have different luminous intensity distribution in different view angles. Curve A in the figure is a luminous intensity distribution of red light; Curve B in the figure is a luminous intensity distribution of green light; Curve C in the figure is a luminous intensity distribution of blue light. As shown in the figure, the luminous intensity distributions of green light and blue light are like inverse U-letter and have the largest luminous intensity value at view angle of zero degree; the luminous intensity distribution of red light is a bimodal distribution and has the largest luminous intensity value at view angles of +40 degrees and −40 degrees. Therefore, the luminous intensity distribution of red light is very different from those of the other two primary-color lights, i.e., green light and blue light, which causes the color shift effect. For example, if the luminous intensity of each of the three primary-color lights is adjusted to be consistent with the other ones at view angle of zero degree, the resultant light observed would be white. However, if the above-mentioned resultant light is observed at other view angles, it is not a white light. Such a color shift effect is a problem in color adjustment.  
         [0008]     Consequently, there is an existing need for a novel and improved display device to solve the above-mentioned problem.  
       SUMMARY OF THE INVENTION  
       [0009]     The primary objective of the invention is to provide a display device having a lenticular lens therein so as to improve the disunity of the luminous intensity distribution of the light emitted by the display device in different view angles, which facilitates color control.  
         [0010]     The other objective of the invention is to provide a display device comprising a substrate, a display module, a lenticular lens and a cap. The display module is attached to the substrate and used for emitting light. The lenticular lens is disposed above the display module and used for changing the luminous intensity distribution of the light emitted by the display module. The cap is disposed above the lenticular lens and sealed with the substrate for capping the lenticular lens and the display module. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a cross-sectional view of a conventional organic light emitting diode;  
         [0012]      FIG. 2  is a schematic illustration of light transportation of the conventional organic light emitting diode of  FIG. 1 ;  
         [0013]      FIG. 3  is a cross-sectional view of a conventional organic light emitting diode display device;  
         [0014]      FIG. 4  are luminous intensity distributions of three primary-color lights emitted from a conventional organic light emitting diode display device observed in different view angles;  
         [0015]      FIG. 5  is a cross-sectional view of an organic light emitting diode display device according to the first embodiment of the present invention;  
         [0016]      FIG. 6  is a luminous intensity distribution of red light emitted from the organic light emitting diode display device according to the first embodiment of the present invention;  
         [0017]      FIG. 7  is a cross-sectional view of an organic light emitting diode display device according to the second embodiment of the present invention is shown;  
         [0018]      FIG. 8  is a luminous intensity distribution of red light emitted from the organic light emitting diode display device according to the second embodiment of the present invention is shown, wherein the glass cap does not touch the display module;  
         [0019]      FIG. 9  is a luminous intensity distribution of red light emitted from the organic light emitting diode display device according to the second embodiment of the present invention is shown, wherein the glass cap touches the display module directly;  
         [0020]      FIG. 10  is a cross-sectional view of an organic light emitting diode display device according to the third embodiment of the present invention; and  
         [0021]      FIG. 11  is a cross-sectional view of an organic light emitting diode display device according to the fourth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     Referring to  FIG. 5 , a cross-sectional view of an organic light emitting diode display device according to the first embodiment of the present invention is shown. The display device  30  comprises a substrate  31 , a display module (for example, a organic light emitting diode)  32 , a lenticular lens  33  and a cap (for example, a glass cap)  34 .  
         [0023]     The display module  32  is attached to the upper surface of the substrate  31  and adapted for emitting light. The light emitted from the display module  32  includes three primary-color lights, namely red light, green light and blue light.  
         [0024]     The lenticular lens  33  is a typical element, which is provided by Entire Tech. Co., Ltd, and its model number is PLS-99. The lenticular lens  33  is disposed above the display module  32  and has the function of diverging light, which is used for changing the luminous intensity distribution of the red light emitted by the display module  32 . In the embodiment, the lenticular lens  33  is adhered to the upper surface of the display module  32  by utilizing UV curing adhesives or hot melt adhesives and disposed apart from the cap  34  by a predetermined distance. The thickness of the UV curing adhesives or hot melt adhesives is about 12.m.  
         [0025]     In the embodiment, the cap is a glass cap  34  with legs that are sealed with the substrate  31  by sealant  35 . The glass cap  34  is used for capping the display module  32  and lenticular lens  33  to form a package structure. Alternatively, the cap has a recess for accommodating the display module  32  or the lenticular lens  33 . The recess is adjustable.  
         [0026]     The display device  30  of this embodiment is made by the following steps: (a) providing a substrate  31 ; (b) attaching a display module  32  onto the substrate  31 ; (c) disposing a lenticular lens  33  above the display module  32  wherein the lenticular lens  33  is attached to the upper surface of the display module  32 ; (d) disposing a cap  34  above the lenticular lens  33 ; and (e) sealing the cap  34  with the substrate  31  for capping the lenticular lens  33  and the display module  32 .  
         [0027]     Referring to  FIG. 6 , a luminous intensity distribution of red light emitted from the organic light emitting diode display device according to the first embodiment of the present invention is shown, wherein the testing instrument used is TOPCON BM-7 luminance meter (the following embodiments are tested by this instrument). Curve A in the figure is a luminous intensity distribution of red light of a conventional organic light emitting diode display device, i.e., curve A of  FIG. 4 . Curve D in the figure is a luminous intensity distribution of red light that is like an inverse U-letter. As shown in the curve, the red light of the first embodiment has the largest luminous intensity value at view angles of +30 degrees and −30 degrees. The embodiment can be used when the luminous intensity distributions of green light and blue light are like an inverse U-letter.  
         [0028]     Referring to  FIG. 7 , a cross-sectional view of an organic light emitting diode display device according to the second embodiment of the present invention is shown. This embodiment is substantially similar to the first embodiment except the position of lenticular lens  33  is different. In this embodiment, the lenticular lens  33  is attached to the upper surface of the glass cap  34 . The advantage of this embodiment is that the distance between the lenticular lens  33  and the display module  32  can be adjusted by changing the height of the glass cap  34  to obtain the desired luminous intensity distribution of red light according to the luminous intensity distributions of green light and blue light in the display device. The minimum value of the preferable range of the distance between the lenticular lens  33  and the display module  32  is the thickness of the glass cap  34 , that is, the glass cap  34  touches the display module  32  directly. The luminous intensity distribution of red light in such condition is shown in curve F of  FIG. 9 . The maximum value of the preferable range of the distance between the lenticular lens  33  and the display module  32  is about 1.1 mm, and the luminous intensity distribution of red light in such condition is shown in curve E of  FIG. 8 .  
         [0029]     The display device  30  of this embodiment is made by the following steps: (a) providing a substrate  31 ; (b) attaching a display module  32  onto the substrate  31 ; (c) providing a lenticular lens  33  and a cap  34 , wherein the cap  34  has a upper surface thereof and a lower surface thereof; (d) attaching the lenticular lens  33  to the upper surface of the cap  34 ; and (e) sealing the cap  34  with the substrate  31  for capping the display module  32 .  
         [0030]     Referring to  FIG. 8 , a luminous intensity distribution of red light emitted from the organic light emitting diode display device according to the second embodiment of the present invention is shown, wherein the glass cap  34  does not touch the display module  32 . Curve A in the figure is a luminous intensity distribution of red light of a conventional organic light emitting diode display device, i.e., curve A of  FIG. 4 . Curve E in the figure is a luminous intensity distribution of red light under this condition of the second embodiment. In comparison with curve A, curve E has the largest luminous intensity value at the view angle of zero degree and approaches curves B and C shown in  FIG. 4 . As a result, the luminous intensity distributions of three primary-color lights are fairly consistent with each other so as to facilitate color control.  
         [0031]     Referring to  FIG. 9 , a luminous intensity distribution of red light emitted from the organic light emitting diode display device according to the second embodiment of the present invention is shown, wherein the glass cap  34  touches the display module  32  directly. Curve A in the figure is a luminous intensity distribution of red light of a conventional organic light emitting diode display device, i.e., curve A of  FIG. 4 . Curve E in the figure is a luminous intensity distribution of red light under this condition of second embodiment. In comparison with curve A, curve E has the largest luminous intensity value at the view angle of zero degree. Curve F is similar to curve E ( FIG. 8 ) except that slope of curve F is larger than that of curve E.  
         [0032]     Referring to  FIG. 10 , a cross-sectional view of an organic light emitting diode display device according to the third embodiment of the present invention is shown. This embodiment is substantially similar to the first embodiment except for the position of lenticular lens  33 . In this embodiment, the lenticular lens  33  is attached to the lower surface inside the glass cap  34 .  
         [0033]     The display device  30  of this embodiment is made by the following steps: (a) providing a substrate  31 ; (b) attaching a display module  32  onto the substrate  31 ; (c) providing a lenticular lens  33  and a cap  34 , wherein the cap  34  has a upper surface thereof and a lower surface thereof; (d) attaching the lenticular lens  33  to the lower surface of the cap  34 ; and (e) sealing the cap  34  with the substrate  31  for capping the display module  32 .  
         [0034]     Referring to  FIG. 11 , a cross-sectional view of an organic light emitting diode display device  40  according to the fourth embodiment of the present invention is shown. This embodiment is substantially similar to the third embodiment except that the glass cap  34  and lenticular lens  33  in the third embodiment are replaced by a combined lenticular lens  43  in this fourth embodiment. As shown in the figure, the combined lenticular lens  43  itself has a cap-like shape with legs that are sealed with the substrate  41  by sealant  44  for capping the display module  42  to form a package structure. Therefore, the manufacturing and assembly cost caused by attaching the lenticular lens to the glass cap are reduced.  
         [0035]     The display device  40  of this embodiment is made by the following steps: (a) providing a substrate  41 ; (b) attaching a display module  42  onto the substrate  41 ; (c) providing a lenticular lens  43 , wherein the lenticular lens  43  is in a cap-like shape and is used for changing the luminous intensity distribution of the light emitted by the display module  42 ; (d) disposing the lenticular lens  43  above the display module  42 ; and (e) sealing the lenticular lens  43  with the substrate  41  for capping the display module  42 .  
         [0036]     While several embodiments of this invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of this invention are therefore described in an illustrative but not restrictive sense. It is intended that this invention may not be limited to the particular forms as illustrated, and that all modifications which maintain the spirit and scope of this invention are within the scope as defined in the appended claims.