JP4872696B2 - Curved surface light source device and method for manufacturing curved liquid crystal display device - Google Patents

Description

The present invention relates to a curved surface light source device having a concave shape, a convex shape, or a waveform as a whole, and a method for manufacturing a liquid crystal display device.

Patent Document 1 discloses a backlight device including a light guide plate in which one side end face of a light guide plate made of a light-transmitting material is a light incident portion, and a light source disposed in the vicinity of the light incident portion, and the backlight device There has been proposed a liquid crystal display device comprising a liquid crystal panel arranged on the top. Further, Patent Document 2 proposes a backlight device that includes a minute concave or convex light reflecting portion on the surface of the light guide plate and uniformly emits light incident from the end surface from the entire surface of the light guide plate. .
JP 2004-31023 A JP-A-8-327807

  Both of the liquid crystal display devices disclosed in Patent Documents 1 and 2 and the backlight device used therefor are flat planar devices. However, in recent years, there is a demand for a curved display screen in order to improve the design of a display device (for example, an image display device, a mobile phone, or a portable information terminal) equipped with a liquid crystal display device. However, since the conventional liquid crystal display device has a flat shape, in order to obtain a curved display screen, a pseudo curved surface must be formed by changing the arrangement angle of a plurality of flat liquid crystal display devices. Did not get.

Accordingly, the present invention provides a method for manufacturing a liquid crystal display device or a planar light source device which is a single liquid crystal display device or a planar light source device, and has a concave shape, a convex shape or a waveform as a whole.

The manufacturing method of the curved surface light source device according to the present invention is as follows.
At least one side end face of the planar light guide plate made of a translucent material is used as a light incident portion, and a plurality of concave or convex light reflecting portions are formed on the front surface or the back surface of the light guide plate, or both, and Preparing a planar light source device that emits light incident from the light incident portion from the surface of the light guide plate ;
A first mold having a concave first surface having a predetermined curvature in one direction and a second mold having a convex second surface having the predetermined curvature in the one direction corresponding to the first surface. Preparing two molds;
A frame made of a metal plate is disposed so that the first surface of the frame is opposed to the first surface of the first mold and the second surface of the frame is opposed to the second surface of the second mold . In a state where the first mold and the second mold are clamped to give a curved shape to the frame ;
In the frame curved shape is imparted, anti-incident side away from the incident side and the light incident portion closer to the light incident portion of the light guide plate causes facing the back surface of the light guide plate to the second surface of the frame the while being opposed to the one direction, mounting the surface light source device provided with a step for holding the surface light source device to the curved surface by the locking portion provided in the wall portion of the four sides of the frame ,
The light reflecting portions in the planar light source device are characterized by being distributed at a high density on the incident side near the light incident portion and at a low density on the non-incident side away from the light incident portion .

A method for manufacturing a curved liquid crystal display device according to the present invention includes:
At least one side end face of the planar light guide plate made of a translucent material is used as a light incident portion, and a plurality of concave or convex light reflecting portions are formed on the front surface or the back surface of the light guide plate, or both, and Preparing a planar light source device that emits light incident from the light incident portion from the surface of the light guide plate;
Preparing a liquid crystal module;
A first mold having a concave first surface having a predetermined curvature in one direction and a second mold having a convex second surface having the predetermined curvature in the one direction corresponding to the first surface. A step of preparing two molds, and a frame made of a metal plate, with the first surface of the frame opposed to the first surface of the first mold and the second surface of the frame being the second A step of applying a curved shape to the frame by clamping between the first mold and the second mold while facing the second surface of the mold;
The back surface of the light guide plate is opposed to the second surface of the frame, and the light incident side of the light guide plate close to the light incident part and the anti-incident side away from the light incident part. Mounting the planar light source device in a state of facing the one direction, and holding the planar light source device in the curved shape by a locking portion provided on the four side walls of the frame;
The step of attaching the liquid crystal module along the planar light source device held in the curved surface shape on the opposite side of the frame with the planar light source device interposed therebetween,
The light reflecting portions in the planar light source device are characterized by being distributed at a high density on the incident side near the light incident portion and at a low density on the non-incident side away from the light incident portion.

  According to the present invention, a curved surface light source device and a curved liquid crystal display device can be easily obtained by using one liquid crystal display device or a planar light source device.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In the following description, the terms “up”, “down”, “left”, “right” and other terms including specific terms are used as necessary to indicate a specific direction. These terms are intended to facilitate understanding of the referenced invention and do not limit the technical scope of the invention.

Embodiment 1

  FIG. 1 shows a liquid crystal display device 10 according to the present invention. As shown in the figure, the liquid crystal display device 10 has an external shape of a square plate having a predetermined thickness and is curved in a concave shape as a whole. In the embodiment, the liquid crystal display device 10 has an external shape of a rectangular plate, and a central portion is curved downward with respect to both end portions in the long side direction. However, the present invention as a whole has a shape in which the central portion is curved upward with respect to both ends in the long side direction, and a shape in which the central portion is curved upward or downward with respect to both ends in the short side direction (not shown). In addition, the liquid crystal display device 10 ″ (see FIGS. 15A and 15B) having a central portion curved in a waveform upward and downward with respect to either the long side direction or the short side direction is also included.

  The liquid crystal display device 10 includes a liquid crystal panel 12 having a rectangular plate appearance and a backlight device of a planar light source device having an appearance similar to that of the liquid crystal panel 12 and disposed under the liquid crystal panel 12. 14

  The liquid crystal panel 12 is a transmissive liquid crystal panel, and has a rectangular light emitting surface (image display surface) 16 facing the opposite side of the backlight device 14 (upward in the figure), and the periphery of the light emitting surface 16 is a frame. Surrounded by 18. Due to the nature of the invention, the driving method of the liquid crystal panel 12, the liquid crystal alignment method, the liquid crystal material, etc. are not limited.

  Referring to FIG. 2, the backlight device 14 includes a backlight assembly 20 and a base frame 22 that holds the backlight assembly 20. Referring to FIG. 3, the backlight assembly 20 has a frame 24 formed of a rectangular frame, similar to a known backlight assembly. The frame 24 is made of, for example, a synthetic resin, and a plurality of concave portions 28 are formed at equal intervals from the inner side to the outer side at the inner edge portion of one frame portion 26 extending in the short side direction. A reflective plate or a reflective sheet 30 is attached to the lower surface of the frame 24. Inside the frame 24, a rectangular light guide plate 32, a diffusion sheet 34, a lower prism sheet 36, and an upper prism sheet 38 are accommodated on a reflection sheet 30. The optical sheet group is covered with a non-translucent frame sheet 40 whose lower surface has adhesiveness, and is attached to the peripheral edges of the frame 24 and the upper prism sheet 38. The frame sheet 40 holds an LED 42 as a light source at a location corresponding to the recess 28 of the frame 24. In addition, the lower surface of the frame sheet 40 is provided with wiring for connecting to the LED 42 and a power source (not shown).

  The light guide plate 32 is a plate made of a translucent material, and the side end face facing the concave portion 28 of the frame 24 and the LED 42 accommodated therein is used as the light incident portion 44. In the embodiment, A large number of concave or convex light reflecting portions are formed on the lower surface facing the reflection sheet 30. FIG. 4 shows an example of the light reflecting portion 46, in which a concave portion formed from the lower surface toward the inside is shown as the light reflecting portion 46. In this embodiment, although the light reflection part 46 is substantially hemispherical, the shape is arbitrary. The density of the light reflecting portion 46 will be described later.

  Returning to FIG. 2, the base frame 22 is formed by processing, for example, a stainless steel metal plate, and has a bottom plate portion 48 having substantially the same planar shape as the backlight assembly 20, and upwards from the four side edges of the bottom plate portion 48. It has the some wall part 50 which stood up. The height of the wall 50 is approximately equal to the thickness of the backlight assembly 20.

  As shown in FIG. 5, an appropriate portion of the wall portion 50 is formed with a locking portion 52 that protrudes inward by bending the upper end of the wall portion 50 at a right angle. The length of the locking portion 52 does not damage the backlight assembly 20 when the backlight assembly 20 is mounted on the base frame 22, and the base frame 22 is mounted with the backlight assembly 20 mounted thereon. The back light assembly 20 is set so as to be securely held along the bottom plate portion 48 of the frame 22.

  Another method of locking the backlight assembly 20 and the base frame 22 is shown in FIGS. In the illustrated method, a fixing protrusion 50a that protrudes inward is formed at an appropriate location on the wall 50 by recessing a part thereof inward. On the other hand, the base frame 20 accommodates the protrusion 50a on the side end surface of the frame 24 facing the protrusion 50a in a state where the backlight assembly 20 is mounted, with the backlight assembly 20 mounted on the backlight assembly 20. A recess 24a is formed. In the present embodiment, the recess 24a is formed by cutting the upper edge of the frame 24, and the engagement step portion 24b is formed at the bottom of the recess 24a (the portion in contact with the bottom plate portion 48). Therefore, when the backlight assembly 20 is mounted on the base frame 22, the wall 50 is elastically deformed outward by the contact between the protrusion 50a and the engagement step 24b, and then the protrusion 50a gets over the engagement step 24b. The protrusion 50 a fits into the recess 24 a and fixes the backlight assembly 20 to the base frame 22.

  Accordingly, the height of the protrusion 50a is such that the wall portion 50 does not damage the frame 24 (particularly, the step portion 24b) when the backlight assembly 20 is mounted on the base frame 22, and the backlight assembly 20 is not damaged. The backlight assembly 20 can be securely held along the bottom plate portion 48 of the base frame 22 in a state where the 20 is mounted. In addition, the protrusion 50a may be formed by deforming a part of the wall portion 50, or may be formed by attaching another member to the inner surface of the wall portion 50. Moreover, the dent 24a may be a simple concave hole having an arbitrary inner surface shape (for example, hemispherical, rectangular). Furthermore, since the recess 24a only needs to be able to fix the backlight assembly 20 to the base frame 22 by engaging with the protrusion 50a, it may be approximately the same size as the protrusion 50a, or may be slightly smaller than the protrusion 50a. It can be large.

  Here, since the periphery of the backlight assembly 20 is fixed by the wall portion 50 of the base frame 22 as shown in FIG. 2, when the frame 24 is thermally expanded, the backlight assembly 20 is centered in the curved direction. The most force is applied, and the backlight assembly 20 tries to lift from the base frame 22. Therefore, it is preferable to provide the above-mentioned locking part 52 and the protrusion 50a at the central part of the base frame 22 in the curved direction or in the vicinity thereof.

  By the way, in the backlight device which is not curved, a hole or an opening is provided in the wall portion 50 of the base frame 22, and a protruding portion is provided at a position facing the hole or the opening in the frame 24. In many cases, the backlight assembly 20 is fixed to the base frame 22 by engaging them. However, when the base frame 22 having holes or openings in the wall 50 is curved as described above, the wall 50 of the portion having the holes or openings is deformed into an unintended shape, and the deformed portion interferes with the frame 24. The trouble of doing occurs. In order to prevent such deformation, when the base frame 22 is bent, only the wall portion in which the hole or the opening is formed is not bent, and when the liquid crystal panel 12 and the backlight device 14 are attached, The problem that the sticking in the location which is not curved becomes weak arises.

  The base frame 22 configured in this way is given a curved shape with a desired curvature by an appropriate processing method. Specifically, for example, the base plate 22 is curved by sandwiching the bottom plate portion 48 between two molds each having a convex surface and a concave surface having a predetermined curvature having substantially the same area as the bottom plate portion 48 of the base frame 22. Shape is added. The curvature radii of the convex surface and the concave surface prepared at this time are assumed to be smaller than the curvature radius of the target curved shape in consideration of the shape restoration property at the time of release. In addition, heat may be applied to the base frame 22 through a mold during processing.

  The backlight assembly 20 is attached to the base frame 22 provided with a predetermined curved shape, and the backlight device 14 is obtained. The mounted backlight assembly 20 is held by a locking portion 52 provided on the four side wall portions 50 and is given a curved shape following the shape of the bottom plate portion 48. In order to prevent the backlight assembly 20 from being separated or detached from the base frame 22 due to the elasticity of the backlight assembly 20, a double-sided tape 54 is attached to the inner surface of the bottom plate portion 48 as shown by a dotted line in FIG. The backlight assembly 20 may be securely held by the tape 54.

  Incidentally, as shown in FIG. 8B, in the conventional backlight device 15, the reflection sheet 31 on the lower surface side is housed in the frame 25. However, when the backlight assembly 20 is mounted on the curved base frame 22, the sheet tends to be displaced when the reflective sheet 30 touches the base frame 22, and there is a possibility that it takes time to assemble. Therefore, as shown in FIG. 8A, it is preferable that the size of the reflection sheet 30 is made larger than the inside of the frame 24 and the reflection sheet 30 is attached to the frame 24 via the double-sided tape 33.

  As shown in FIG. 1, the liquid crystal panel 12 is attached to the backlight device 14 having a curved shape. Preferably, a double-sided tape (not shown) is attached between the liquid crystal panel 12 and the backlight device 14, for example, on the upper surface of the frame sheet 40, and the liquid crystal panel 12 is fixed to the backlight device 14 via this double-sided tape. It is preferable to do.

  FIG. 9 shows the distribution of the amount of light emitted from each point (pixel) of the liquid crystal display device. Specifically, as shown in FIG. 9A, in the case of a flat liquid crystal display device 100, the light quantity distribution 104 emitted from each point 102 is substantially equal. Therefore, when the light emitting surface of the liquid crystal display device 10 is viewed from the front, the light amount at each point (the light amount 108 in the direction 106 extending vertically from each point) is substantially equal. However, as shown in FIG. 9B, when the liquid crystal display device 100 ′ is curved in a concave shape, the light amount distribution 104 ′ of each point 102 ′ varies depending on the location, and the direction 106 ′ extending vertically from the point 102 ′. The amount of light 108 'differs from point to point. Therefore, in the liquid crystal display device 10 and the backlight device 14 according to the present invention, as shown in FIG. 10, the density of the light reflecting portions 46 in the light guide plate 32 (area ratio (%) occupied by the light reflecting portions per unit area). However, the light guide plate 32 is designed so as to have a distribution different from the density of the flat light guide plate having a flat shape.

  Specifically, as shown in FIG. 1, when the light emitting surface is curved in a concave shape, the density of the light reflecting portions 46 is high on the incident side of the light guide plate 32 close to the LED 42, and the anti-incident of the light guide plate 32 away from the LED 42. On the side, the density of the light reflecting portion 46 is low. Further, when the light emitting surface is curved in a convex shape, the density of the light reflecting portions 46 is lower on the incident side of the light guide plate 32 close to the LED 42 than the flat flat light guide plate, and the light guide plate separated from the LED 42 On the non-incident side 32, the density of the light reflecting portions 46 is higher. Therefore, in the liquid crystal display device 10 and the backlight device 14 of the present invention curved in a convex shape or a concave shape, uniform brightness can be obtained over the entire surface as in the flat liquid crystal display device and the backlight device. Even in a liquid crystal display device and a backlight device curved in a waveform, the density of the light reflecting portion 46 is adjusted according to the location of the convex portion and the concave portion, which can obtain uniform brightness over the entire surface. The

Embodiment 2

  FIG. 11 shows a double-sided light emitting liquid crystal display device 10 'according to the present invention. As shown in the figure, the double-sided light emitting liquid crystal display device 10 ′ has liquid crystal panels 12 ′ and 12 ″ disposed above and below the backlight device 14, respectively, and is curved in a concave shape as a whole. The sizes of 12 ′ and 12 ″ may be the same, or one may be smaller than the other as shown.

  In the double-sided light emitting liquid crystal display device 10 ′, as shown in FIG. 12, the backlight device 14 ′ includes a backlight assembly 20 ′ and a base frame 22 ′ as in the first embodiment, and a bottom plate of the base frame 22 ′. In the part 48, a window part 55 for illuminating the lower liquid crystal panel 12 ″ is opened.

  The backlight assembly 20 'has the same configuration as the backlight assembly 20 of the first embodiment shown in FIG. Here, the reflection sheet (not shown in FIG. 12) disposed below the light guide plate has a reflectance of not 100% in order to irradiate light to the lower liquid crystal panel 12 ″. A part of the light irradiated downward can pass through the reflection sheet and the window 55 to irradiate the liquid crystal panel 12 ″ below. Here, as shown in the first embodiment, if the upward irradiation light is adjusted to uniform brightness throughout, the downward irradiation light also becomes uniform.

Embodiment 3

  In the first or second embodiment, the base frame 22 is processed into a convex shape, a concave shape, or a corrugated shape as a whole, and the backlight assembly 20 and the liquid crystal panel 12 are mounted along the processed shape. After the flat backlight device 14 formed by mounting the flat backlight assembly 20 is formed, the backlight device 14 is formed into a desired curved shape using the curved surface processing apparatus or the curved surface processing jig 54 shown in FIG. May be processed. As shown in the figure, the curved surface processing jig 54 includes a lower mold 60 and an upper mold 62 each having a convex surface 56 and a concave surface 58 having a predetermined curvature radius (for example, a curvature radius of 50 mm to 200 mm). The backlight device 14 is sandwiched by the mold 62, and a curvature corresponding to the uneven surface is given to the backlight device 14. At this time, the pressure applied to the backlight device 14 may be a minimum pressure that can deform the backlight device 14 according to the uneven surface in order to prevent damage to the backlight device 14. Further, when processing a curved surface, the ambient atmosphere temperature is determined within a range in which the backlight device 14 is not thermally damaged. Furthermore, the heating time varies depending on the radius of curvature applied to the backlight device 14, and the heating time increases as the radius of curvature decreases.

Other embodiments

  In the above embodiment, the liquid crystal display device 10 and the backlight device 14 are processed into a concave shape, a convex shape, or a corrugated shape as a whole, as shown in FIGS. 14 (a) and 14 (b) and FIGS. 15 (a) and 15 (b). Thus, it is preferable to process the whole into a concave shape, a convex shape, or a waveform except for one end side 64 where the LED 42 and its wiring are formed.

  In the above description, the LED 42 is used as the light source, but a cold cathode tube may be used instead.

1 is a perspective view of a curved liquid crystal display device according to the present invention. 1 is an exploded perspective view of a curved surface light source device according to the present invention. FIG. 3 is an exploded perspective view of a backlight unit incorporated in the apparatus of FIGS. The partial expanded sectional view of a light-guide plate. The partial expanded sectional view of a base frame. The perspective view which shows another locking method of a backlight assembly and a base frame. The top view which shows another latching method of a backlight assembly and a base frame. Sectional drawing of this invention and the conventional backlight apparatus. The light quantity distribution figure of the light radiate | emitted from a liquid crystal display device. The density distribution figure of the light reflection part in a light-guide plate. The side view of the double-sided light emission type liquid crystal display device which concerns on this invention. The disassembled perspective view of the backlight apparatus integrated in the apparatus of FIG. The perspective view of the curved surface processing jig of a backlight apparatus. FIG. 14A is a perspective view and FIG. 14B is a side view of a liquid crystal display device according to another embodiment. FIG. 15A is a perspective view and FIG. 15B is a side view of a liquid crystal display device according to another embodiment.

Explanation of symbols

10: liquid crystal display device, 12: liquid crystal panel, 14: backlight device, 16: light emitting surface, 18: frame, 20: backlight unit, 22: base frame, 24: frame, 26: frame portion, 28: recess, 30: Reflective sheet, 32: Light guide plate, 34: Diffusing sheet, 36: Lower prism sheet, 38: Upper prism sheet, 40: Frame sheet, 42: LED, 44: Light incident part, 46: Light reflecting part, 48: Bottom plate part, 50: wall part, 52: locking part, 54: curved surface processing jig.

Claims (2)

At least one side end face of the planar light guide plate made of a translucent material is used as a light incident portion, and a plurality of concave or convex light reflecting portions are formed on the front surface or the back surface of the light guide plate, or both, and Preparing a planar light source device that emits light incident from the light incident portion from the surface of the light guide plate ;
A first mold having a concave first surface having a predetermined curvature in one direction and a second mold having a convex second surface having the predetermined curvature in the one direction corresponding to the first surface. Preparing two molds;
A frame made of a metal plate is disposed so that the first surface of the frame is opposed to the first surface of the first mold and the second surface of the frame is opposed to the second surface of the second mold . In a state where the first mold and the second mold are clamped to give a curved shape to the frame ;
In the frame curved shape is imparted, anti-incident side away from the incident side and the light incident portion closer to the light incident portion of the light guide plate causes facing the back surface of the light guide plate to the second surface of the frame the while being opposed to the one direction, mounting the surface light source device provided with a step for holding the surface light source device to the curved surface by the locking portion provided in the wall portion of the four sides of the frame ,
The curved surface type characterized in that the light reflecting portions in the planar light source device are distributed at a high density on the incident side near the light incident portion and at a low density on the non-incident side away from the light incident portion. Manufacturing method of planar light source device. At least one side end face of the planar light guide plate made of a translucent material is used as a light incident portion, and a plurality of concave or convex light reflecting portions are formed on the front surface or the back surface of the light guide plate, or both, and Preparing a planar light source device that emits light incident from the light incident portion from the surface of the light guide plate;
Preparing a liquid crystal module;
A first mold having a concave first surface having a predetermined curvature in one direction and a second mold having a convex second surface having the predetermined curvature in the one direction corresponding to the first surface. A step of preparing two molds, and a frame made of a metal plate, with the first surface of the frame opposed to the first surface of the first mold and the second surface of the frame being the second A step of applying a curved shape to the frame by clamping between the first mold and the second mold while facing the second surface of the mold;
The back surface of the light guide plate is opposed to the second surface of the frame, and the light incident side of the light guide plate close to the light incident part and the anti-incident side away from the light incident part. Mounting the planar light source device in a state of facing the one direction, and holding the planar light source device in the curved shape by a locking portion provided on the four side walls of the frame;
The step of attaching the liquid crystal module along the planar light source device held in the curved surface shape on the opposite side of the frame with the planar light source device interposed therebetween,
The curved surface type characterized in that the light reflecting portions in the planar light source device are distributed at a high density on the incident side near the light incident portion and at a low density on the non-incident side away from the light incident portion. A method for manufacturing a liquid crystal display device.

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