The present application claims priority from Japanese application JP 2012-167619 filed on Jul. 27, 2012, the content of which is hereby incorporated by reference into this application.
1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
In a self-luminous liquid crystal display device including a backlight, as disclosed in JP 2007-206125A, a substantially rectangular liquid crystal display panel and a substantially rectangular backlight are fixed by attaching a double-sided tape along the outer periphery of each of them.
In the structure as disclosed in JP 2007-296125A, a gap is formed between the liquid crystal display panel and the backlight by the thickness of the adhesive tape. Thus, uneven brightness may occur due to the warp of the liquid crystal display panel or the intrusion of a foreign material into the gap.
The invention is made in view of such circumstances, and an object thereof is to provide a liquid crystal display device in which the warp of a liquid crystal display panel and the intrusion of a foreign material into a gap between the liquid crystal display panel and a backlight can be prevented.
The outline of representative inventions disclosed in the present application will be briefly described below.
(1) A liquid crystal display device includes a liquid crystal display panel including an image forming area where pixels are arranged and an image is formed, a backlight which is a flat light source, and a transparent support member which is disposed between the liquid crystal display panel and the backlight and is in surface contact with the liquid crystal display panel and the backlight over an entire area of the image forming area.
(2) In the liquid crystal display device of (1), the transparent support member includes plural laminated plate-like members different in size.
(3) In the liquid crystal display device of (1), the transparent support member includes a step at an end.
(4) In the liquid crystal display device of any one of (1) to (3), the transparent support member is bonded to the liquid crystal display panel and the backlight.
(5) In the liquid crystal display device of any one of (1) to (4), an outer peripheral part of the transparent support member has a light-shielding property.
According to (1), the liquid crystal display device can be obtained in which the warp of the liquid crystal display panel and the intrusion of a foreign material into a gap between the liquid crystal display panel and the backlight can be prevented.
According to (2) or (3), when the backlight includes a convex part having a step at an outer periphery of the image forming area, the transparent support member is supported without rattling.
According to (4), a double-sided tape for bonding the liquid crystal display panel and the backlight is not required.
According to (5), a special structure for preventing light from leaking to the outer periphery of the image forming area is not required.
Hereinafter, a first embodiment of the invention will be described with reference to
The liquid crystal display panel 1 is a common transmissive liquid crystal display panel and has such a structure that liquid crystal is sandwiched between a first substrate 10 called a color filter substrate and a second substrate 11 called a TFT substrate.
Pixel electrodes as electrodes corresponding to many pixels regularly arranged in lattice form are formed on a surface of the second substrate 11, and a TFT (Thin Film Transistor) is connected to each of the pixel electrodes. The ON-OFF of the TFT is controlled, and a voltage corresponding to an image to be displayed is applied to each of the pixel electrodes, so that a desired electric field passing through the liquid crystal is generated, and the orientation direction of the liquid crystal is controlled. The polarization direction of a light beam passing through the liquid crystal layer having the specific orientation is changed. A polarization plate 12 is bonded to each of a front surface of the first substrate 10 and a back surface of the second substrate 11, and allows the light beam having the specific polarization direction to pass through. By this structure, the transmittance of the light beam passing through each of the pixels is controlled by the voltage applied to each of the pixel electrodes, and an image is formed. Accordingly, in an area occupied by the liquid crystal display panel 1, an area where the pixels are formed is an image forming area 13 where an image is formed. In the drawing, the image forming area 13 is a rectangular area indicated by a broken line. Besides, a front surface of one side of the second substrate 11 is exposed, and an FPC (Flexible Printed Circuits) 14 for electrical connection to an external equipment is connected.
Incidentally, although the driving system of the liquid crystal display panel 1 of the liquid crystal display device 100 of this embodiment is an IPS (In Plane Switching) system, no limitation is made to the system, and any well-known system may be used. For example, a TN (Twisted Nematic) system or a VA (Vertical Alignment) system may be used.
The backlight 2 is a flat light source for uniformly illuminating the whole surface of the image forming area 13. The backlight 2 includes a backlight case 20 for housing various members constituting the backlight 2, and a light-emitting surface 21 which is positioned in an opening of a front surface of the backlight case 20 and the size and shape of which are equal to or slightly larger than those of the image forming area 13. As shown in the drawing, since the light-emitting surface 21 is at a position lower than the front surface of the backlight case 20 by one step toward the back surface side, the front surface of the backlight case 20 is a convex part 22 surrounding the outer periphery of the image forming area 13 and protruding toward the front surface side.
The light source of the backlight 2 and the type thereof are not particularly limited but may be arbitrary. For example, a CCFL (Cold Cathode Fluorescent Lamp), an LED (Light-Emitting Diode) or an EL (Electro Luminescence) illumination may be used as the light source. An FPC 23 for electric connection to the external equipment extends from the back surface of the backlight 2.
The adhesive member 3 is a black or deep color double-sided tape having a rectangular frame shape, and bonds the front surface of the convex part 22 of the backlight case 20 to the back surface outer peripheral part of the liquid crystal display panel 1, so that the liquid crystal display panel 1 and the backlight 2 are fixed to each other. The adhesive member 3 has the black or deep color in order to prevent a light beam from the backlight 2 from leaking to the outside of the image forming area 13.
The transparent support member 4 is a plate which is transparent and the shape and size of which are equal to or slightly larger than those of the image forming area 13. The flat shape thereof has such a size that the support member is fitted in the opening of the front surface of the backlight case 20. Besides, the thickness of the transparent support member 4 is selected so that when the liquid crystal display panel 1 and the backlight 2 are bonded and fixed by the adhesive member 3, the front surface of the transparent support member 4 is in surface contact with the back surface of the image forming area 13 of the liquid crystal display panel 1 over the whole area, and the back surface of the transparent support member 4 is in surface contact with the front surface of the light-emitting surface 21 of the backlight 2. Accordingly, the transparent support member 4 is filled between the back surface of the liquid crystal display panel 1 and the light-emitting surface 21 of the backlight 2 substantially without a gap. Incidentally, here, the surface contact indicates a contact relation in macroscopic view, and a structure in microscopic view, for example, minute surface concaves and convexes due to surface roughness or minute mechanical structures formed on a surface of an optical sheet such as a prism sheet are not considered. The material of the transparent support member 4 is not particularly limited, and glass or transparent resin such as PMMA (Poly Methyl Methacrylate) may be used.
Although the frame 5 is not necessarily an inevitable member, the frame is provided in order to protect the outer peripheral part of the liquid crystal display panel 1 or to prevent separation between the liquid crystal display panel 1 and the backlight 2. Various methods may be used as a fixing method of the frame 5. For example, the frame may be bonded to the outer peripheral part of the front surface of the liquid crystal display panel 1 or may be fixed to the backlight case 20 of the backlight 2 by bonding or screwing.
In the backlight 2, a reflecting sheet 24, a light guide plate 25 and an optical sheet group 26 are housed in this order from the back surface side so as not to drop down to the inside of the backlight case 20. An LED 28 mounted on an LED substrate 27 is disposed so as to face an end face of one side of the light guide plate 25. A light beam irradiated from the LED 28 is introduced into the light guide plate 25, and is propagated to the whole area of the light guide plate 25 while total reflection is repeated between the front surface and the back surface. Besides, a suitable scattering structure, for example, a specified printed pattern of scattering ink is provided on the front surface or the back surface of the light guide plate 25. The reflection direction of the light beam is changed by the scattering structure, and the light beam is extracted toward the front surface side of the light guide plate 25. The reflecting sheet 24 is for again reflecting the light beam, which outgoes from the back surface of the light guide plate 25, toward the light guide plate 25. The optical sheet group 26 is provided so that illumination obtained by the backlight 2 becomes uniform and the brightness thereof becomes high, and may include, for example, a diffusion film or a prism sheet. Here, the front surface of the optical sheet group 26 is the light-emitting surface 21 of
As is apparent from the drawing, the thickness of the transparent support member 4 is substantially equal to the sum of the thickness of the front surface part of the backlight case 20 (that is, the distance between the light emitting surface 21 and the front surface of the backlight case 20) and the thickness of the adhesive member 3. By this, the whole surface of the transparent support member 4 is in surface contact with each of the back surface of the liquid crystal display panel 1 and the light-emitting surface 21 of the backlight 2. By this structure, the liquid crystal display panel 1 is not warped toward the back surface side, and a foreign material does not intrude between the liquid crystal display panel 1 and the backlight 2.
Next, a second embodiment of the invention will be described with reference to
Next, a third embodiment of the invention will be described with reference to
The length of the second transparent support member 42 in one direction (here, in along axis direction) is slightly shorter than that of the first transparent support member 41. By this, when the first transparent support member 41 and the second transparent support member 42 are laminated, the same shape as the step 40 of the second embodiment is obtained. Incidentally, the first transparent support member 41 and the second transparent support member 42 are merely overlapped and arranged, and both are not required to be bonded. However, these members may be bonded.
Next, a fourth embodiment of the invention will be described with reference to
In this embodiment, an adhesive force to a liquid crystal display panel 1 and a backlight 2 is given to the transparent support member 4 itself, so that an adhesive member is not required. A method of giving the adhesive force to the transparent support member 4 is not particularly limited. For example, a transparent adhesive having high transmittance, such as a silicone adhesive, is applied to both surfaces of the transparent support member 4, and the transparent support member may be bonded to each of the liquid crystal display panel 1 and the backlight 2. The transparent support member 4 may be fixed to each of the liquid crystal display panel and the backlight 2 by another method, for example, by attraction caused by electrostatic force or inter-molecular force.
Besides, as shown in
Alternately, an adhesive colored in black or deep color is used, and the transparent support member 4 may be bonded to each of the liquid crystal display panel and the backlight 2 only in the light-shielding area 43.
The forms, arrangement, number and the like of the respective members indicated in the embodiments explained above are mere examples and the invention is not limited to them. When the invention is implemented, those skilled in the art can arbitrary design and modify the forms and the like of the members according the implementation.
While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications maybe made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention.
Number | Date | Country | Kind |
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2012-167619 | Jul 2012 | JP | national |