JP2004354807A - Backlight device for liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily laminate each optical film in a proper direction without any reversal, when laminating a plurality of optical films having an optical axis. <P>SOLUTION: The optical film 22 is provided, which has a specific optical axis arranged in between the liquid crystal display element and a light source. Positioning marks 22a, 22b having the same shape and size are formed at symmetrically at positions of the intersecting point of the horizontal and vertical center lines CL1, CL2 of the optical film 22 with a center as a point O on two opposed sides 221, 222 of the optical film 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a backlight device for a liquid crystal display element, and more particularly, to an optical film having an optical axis for increasing luminance and the like, which is disposed on a light exit surface side of a light guide plate.
[0002]
[Prior art]
The transmissive or semi-transmissive liquid crystal display element has a backlight device on the back side (opposite observation side). There are two types of backlight devices: a sidelight type and a direct type. Both types are used depending on the application of the liquid crystal display element, but the sidelight type is thinner than the direct type, so it is especially used for mobile phones. Is preferably employed in the liquid crystal display device of the above.
[0003]
In a liquid crystal display device having a backlight device, most of the power consumption is consumed by the light source of the backlight device. In order to irradiate the display element, various measures are taken for the backlight device.
[0004]
As an example, a film having predetermined optical characteristics such as a condensing film or a brightness enhancement film is laminated on a light diffusion film that diffuses light from a light source, and the light from the light source is more effectively applied to the liquid crystal display device. That is being done.
[0005]
This prior art will be described with reference to an exploded side view of FIG. 7 taking a sidelight type backlight device as an example. This backlight device includes an optical system unit 1 disposed on the back side (a side opposite to the observation surface) of the liquid crystal display panel P. The optical system unit 1 is housed in the holder 40 together with the liquid crystal display panel P.
[0006]
The optical system unit 1 includes a light guide plate 10 on which light from a light source (not shown) is incident, an optical film laminate 20 disposed on the light exit surface (upper surface) 11 side of the light guide plate 10, and a bottom surface of the light guide plate 10. And a light reflection sheet 30 disposed on the 12th side.
[0007]
The light guide plate 10 is made of, for example, an acrylic resin plate, and light from a light source (not shown) is radiated into the light guide plate 10 with a predetermined side surface serving as a light incident surface 13. In this example, the optical film laminate 20 includes a light diffusion film 21 and three prism films 22, 23, and 24 made of a resin such as polyester or polycarbonate. The illumination light for P is appropriately adjusted.
[0008]
The light diffusion film 21 effectively diffuses (scatters) the light from the light exit surface 11 of the light guide plate 10 to eliminate unevenness of the light, and hides the bright spot dots of the light source appearing on the light guide plate 10 to make the light uniform. Adopted for The prism films 22, 23, and 24 are used to change the directionality of light by using a plurality of sheets to improve the brightness. In this example, the prism films 22, 23 are condensing films, and the prism films 22, 23 are prisms. The film 24 is a brightness enhancement film.
[0009]
The holder 40 is provided with a storage recess 41 in which the optical system unit 1 is stored and an LED storage section 42 arranged on the light incident surface 13 side of the light guide plate 10. Although not shown, the LED housing section 42 houses, for example, a chip type light emitting diode as a light source.
[0010]
By the way, among the optical film laminates 20, optical films such as the light-condensing films 22, 23 and the brightness enhancement film 24 often have optical axes in a predetermined direction, and thus have a predetermined optical axis. It is necessary to laminate in the direction according to
[0011]
However, since most of this kind of optical film is transparent, it is difficult to distinguish between the front and back and the optical axis. Therefore, the front and back and the lamination direction may be confused, and not only the desired effect cannot be obtained, but also the irradiation efficiency is reduced.
[0012]
Therefore, in order to prevent the above-mentioned mistake, conventionally, a predetermined positioning means is applied to the light-collecting films 22 and 23 and the brightness enhancement film 24 and the holder 40, so that the stacking error of the optical film having the predetermined optical characteristics is prevented. Is prevented from occurring.
[0013]
In order to explain the positioning means, one of the light-condensing films 22 and 23 is shown in FIG. 8 and the holder 40 is shown in FIG. In this example, on both sides 221 and 222 of the light-condensing film 22, projections 22a and 22b are formed at different height positions, and the holder 40 has projections 22a and 22b around the storage recess 41. The recesses 43a and 43b into which are fitted are formed.
[0014]
In this conventional example, when the protruding pieces 22a and 22b are fitted into the corresponding concave portions 43a and 43b, respectively, the optical axis XL of the condensing film 22 is designed to be oriented in a correct direction. According to this, when the condensing film 22 is turned upside down, since the protruding pieces 22a and 22b cannot be fitted into the concave portions 43a and 43b, it is noticed that the front and back are opposite.
[0015]
In this way, the wrong insertion of the front and back sides is prevented, but in the conventional example, the condensing film 22 is further provided only in one specific orientation state, that is, the projection 22a faces the recess 43a, and the projection 22b is The holder 40 can be inserted only in a state facing the concave portion 43b.
[0016]
That is, the protruding pieces 22a and 22b are formed at positions deliberately shifted from a diagonal line AL passing through the center point O (the intersection of the horizontal center line CL1 and the vertical center line CL2) of the light-condensing film 22. By making the distance a from CL1 to one protruding piece 22a different from the distance b from the horizontal center line CL1 to the other protruding piece 22b (a ≠ b), the condensing film 22 can be placed in one specific orientation state. Only the insertion into the holder 40 is possible. The projecting piece 22a and the projecting piece 22b may have different sizes and shapes.
[0017]
[Problems to be solved by the invention]
Even if the condensing film 22 is rotated 180 ° clockwise or counterclockwise, the direction of the optical axis XL does not change. However, according to the above-described conventional example, in this case (not upside down, simply upside down). Cannot be inserted into the holder 40), the operator must determine not only the directions of the left and right protruding pieces 22a and 22b but also the top and bottom of the film, which is unnecessary. You will be burdened.
[0018]
Therefore, an object of the present invention is to arrange an optical film having a predetermined optical axis in a light irradiation path from a light source to a liquid crystal display element, to reliably prevent only an arrangement in a reversed state, and to set a direction of the optical axis. An object of the present invention is to reduce the burden on the operator by eliminating the need for the operator to determine the vertical position at which does not change.
[0019]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a liquid crystal display including a light source disposed on a side opposite to a viewing surface of a liquid crystal display element, and an optical film disposed in a light irradiation path from the light source to the liquid crystal display element. In the backlight device for an element, on the two opposite sides of the optical film, positioning marks of the same shape and the same size are respectively provided at point symmetric positions centered on the intersection of the vertical center line and the horizontal center line of the optical film. It is characterized by being formed one by one.
[0020]
According to another aspect of the present invention, there is provided a liquid crystal display comprising: a light source disposed on a side opposite to an observation surface of a liquid crystal display element; and an optical film disposed in a light irradiation path from the light source to the liquid crystal display element. In the backlight device for a display element, a plurality of pairs of positioning marks are formed on two opposing sides of the optical film at point-symmetrical positions centered on the intersection of the vertical center line and the horizontal center line of the optical film. The pair of positioning marks have the same shape and the same size, and the positioning marks formed on the same side are asymmetric with respect to the center point of the side.
[0021]
According to this, if the positioning mark of the optical film is formed in advance at a position where the optical axis of the optical film is oriented in the correct direction, the optical film is rotated clockwise or counterclockwise by 180 degrees. However, since the positioning marks on the optical film appear at the same position only when the positional relationship is changed between before and after rotation, the operator does not need to use extra nerves for the vertical orientation, Quick work can be performed.
[0022]
Also, when the front and back of the optical film are reversed, the positioning marks appear at different positions before and after the reversal, so just confirm the position of the positioning marks and place them inside the holder without changing the front and back. Can be inserted.
[0023]
In the present invention, the positioning mark includes printing, engraving, and the like. However, in the process, it is preferable that the positioning mark be a protruding piece or a notch that can be formed simultaneously with cutting out the optical film. The present invention is applicable to any of a sidelight type and a direct type.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view showing an example of an optical film to which the present invention is applied, FIG. 2 is a plan view showing a holder side thereof, and FIG. 3 is an operation explanatory view of the present invention.
[0025]
The basic configuration of the backlight device of the present invention may be the same as that of the conventional example shown in FIG. 5, and therefore the description thereof is omitted, and here, the light-condensing film 22 included in the optical film laminate 20 is used. An example will be described. The other light condensing film 23 and the brightness enhancement film 24 have the same configuration as the light condensing film 22.
[0026]
The light-condensing film 22 is formed with projecting pieces 22a and 22b projecting from both sides 221 and 222 in a substantially rectangular shape. In this case, the protruding pieces 22a and 22b are arranged such that when the light-condensing film 22 is inserted into the holder 40, the optical axis XL is directed in a predetermined direction.
[0027]
As shown in FIG. 1, the protruding pieces 22a and 22b have the same shape and the same size on a diagonal AL passing through the center point O (the intersection of the horizontal center line CL1 and the vertical center line CL2) of the light-condensing film 22. Is formed. In this example, the diagonal line AL is set to be inclined by a predetermined angle θ from the vertical center line CL2, and the protruding pieces 22a, 22b are arranged such that the midpoints of the protruding sides 22a1, 22b1 are located on the diagonal line AL. I have.
[0028]
That is, the projecting pieces 22a and 22b are in point symmetry with respect to the center point O of the light-condensing film 22, and the distance a from the horizontal center line CL1 to one of the projecting pieces 22a and the other projecting point from the horizontal center line CL1. The distance b to the piece 22b is the same (a = b). Further, the widths and the protruding amounts of the protruding pieces 22a and 22b are also the same.
[0029]
Correspondingly, concave portions 43a and 43b to be fitted with the protruding pieces 22a and 22b are also formed point-symmetrically around the storage concave portion 41 of the holder 40. The recesses 43a and 43b are the same in shape and size as the protruding pieces 22a and 22b except that they are grooves.
[0030]
According to this, even if the light condensing film 22 is rotated 180 degrees clockwise or counterclockwise, in FIG. 1, before rotation, the protrusion 22a on the lower left side is in the same position as the protrusion 22b on the upper right side. Further, before rotation, the position of the projecting piece 22b on the upper right side is merely replaced with the position of the projecting piece 22a on the lower left side (the direction of the optical axis XL does not change).
[0031]
Therefore, assuming that the vertical direction of the light-condensing film 22 is the direction shown by the arrow Y in FIG. 1, the operator simply looks at the vertical relationship between the protruding pieces 22a and 22b, and does not check the vertical direction. Since it is only necessary to position the pieces 22a and 22b in the concave portions 43a and 43b, the working efficiency can be improved. That is, the operator need only confirm that one of the protrusions is at the lower left and the other is at the upper right.
[0032]
In addition, when the front and back of the light-condensing film 22 are reversed, that is, as shown in FIG. 3A, the surface 223 of the light-condensing film 22 is originally arranged toward the open side of the holder 40. As shown in FIG. 3B, when the back surface 224 side of the light-condensing film 22 is arranged toward the open side of the holder 40, the protrusions 22a and 22b and the concave portions 43a and 43b cannot be aligned.
[0033]
In other words, contrary to the above, when one of the protrusions is at the upper left and one of the other protrusions is at the lower right, the worker notices that the front and back are opposite, so that the front and back are not mistaken. The light collecting film 22 can be inserted into the holder 40.
[0034]
Next, a second embodiment of the present invention will be described with reference to FIG. Note that, also in the second embodiment, the basic configuration of the backlight device may be the same as that of the conventional example shown in FIG. 5 as in the first embodiment. FIG. 4 shows only the light-condensing film 22 included in the optical film laminate 20, but the other light-condensing films 23 and the brightness enhancement film 24 have the same configuration as the light-condensing film 22. .
[0035]
In the second embodiment, the light-condensing film 22 is provided with notches 22c and 22d formed by cutting the opposing corner portions 225 and 226 into a triangular shape having the same size including the apex. The holders 40 need not be provided with the concave portions 43a and 43b as in the first embodiment.
[0036]
In this example, as shown in FIG. 4A, the vertical direction of the light-condensing film 22 is the arrow Y direction, and when one notch 22c is at the upper left and the other notch 22d is at the lower right, the optical axis XL is set to be in the correct direction.
[0037]
For this reason, even when the light-collecting film 22 is rotated 180 degrees clockwise or counterclockwise, the notch 22c and the notch 22d are merely replaced by their positions and arrangements. Since the orientation does not change, the operator only needs to determine whether one notch 22c is at the upper left and the other notch 22d is at the lower right.
[0038]
By the way, as shown in FIG. 4A, the front surface 223 of the light-condensing film 22 is originally arranged toward the open side of the holder 40, but as shown in FIG. When the holder 40 is to be arranged toward the open side, one notch 22c is located at the upper right and the other notch 22d is located at the lower left, so that it can be seen that the front and back are opposite.
[0039]
In the second embodiment, the recesses 43a and 43b do not need to be formed around the storage recess 41 of the holder 40, so that it is not necessary to secure an extra space in the holder 40. Therefore, the light irradiation area can be effectively used by the space, and the demand for the compact holder 40 itself can be satisfied.
[0040]
In this manner, according to the present invention, by forming positioning marks such as protruding pieces and notches on each optical film, each optical film is visually inspected in the correct direction, and whether or not each optical film is laminated without turning over. Can be easily confirmed, and the accuracy and speed of the laminating operation can be achieved.
[0041]
Note that the light diffusion film 21 generally has a milky white color, is distinguishable from other optical films, and has no specific directionality. Although no piece or notch is provided, a protrusion or notch may be formed in the light diffusion film 21 as necessary.
[0042]
Further, the shape of the protruding piece is not limited to a square shape, and may be appropriately selected, for example, a triangular shape or a semicircular shape. Similarly, the shape of the notch is not limited to a triangular shape, and may be appropriately selected, for example, an L-shape or a concave shape. In this case, an appropriate position and size may be selected for the formation position of the protruding piece and the cut size of the notch without affecting the illumination range from the light exit surface from the light guide plate.
[0043]
Next, a third embodiment of the present invention will be described. FIG. 5 shows only the light collecting film 22 included in the optical film laminate 20. In the third embodiment, the light-condensing film 22 has a positioning mark composed of two projecting pieces on one side. That is, two pairs of positioning marks 22a, 22b; 22aa, 22bb having the same shape and the same size are formed on two opposing sides.
[0044]
These positioning marks are formed at positions symmetrical with respect to the center point O, and have the same distance from the horizontal center line CL1 to the protruding piece (a = b, c = d). Further, in order to prevent front and back inversion, the protruding pieces 22b and 22bb formed on one side portion 222 orthogonal to the horizontal center line CL1 are formed at positions asymmetric with respect to the horizontal center line CL1 (b ≠ d).
[0045]
According to the third embodiment, even if it is rotated by 180 °, it is only necessary to position the protruding piece without checking the vertical direction, so that the working efficiency is remarkably improved. Further, even if the front and back of the light-condensing film 22 are reversed, the light is immediately noticed, and a backlight device in which the front and back of the light-condensing film 22 are mistaken is not produced.
[0046]
In the third embodiment, the positioning marks 22a, 22b, 22aa, and 22bb are formed in the same shape and the same size. However, the present invention is not limited to this, and different pairs, for example, 22a and 22aa have different sizes and shapes. You may.
[0047]
FIG. 6 shows a modification of the third embodiment, which has three protrusions on one side. Also in this case, the protruding pieces are at asymmetric positions such as a = b = e = f, c = d, and b ≠ d with respect to the center point O of the horizontal center line CL1. Therefore, in the light-collecting film according to the present invention, there is no need to distinguish between the upper and lower sides even if the film is rotated by 180 °, and the positioning mark is provided at a position where the film is immediately noticed when the film is turned upside down.
[0048]
Further, in the above embodiment, the example in which the optical film laminate is constituted by the light diffusion film and the three prism films has been described, but the present invention is not limited to the number and types of the laminate films. Further, the backlight device of the above embodiment is a sidelight type, but the present invention is also applicable to a direct type backlight device.
[0049]
【The invention's effect】
As described above, according to the present invention, in a backlight device for a liquid crystal display element in which an optical film having a predetermined optical axis is arranged between a liquid crystal display element and a light source, two opposite sides of the optical film In order to prevent front / back inversion by forming the same and same size positioning marks at a point symmetric position centered on the intersection of the horizontal center line and the vertical center line of the optical film, the two positioning marks themselves are used. Since it is only necessary to judge whether the position of each positioning mark is at a regular position in design or not, the accuracy and speed of the positioning operation of the optical film can be achieved.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing an optical film according to a first embodiment of the present invention.
FIG. 2 is a plan view schematically showing a holder according to the first embodiment of the present invention.
FIG. 3 is a plan view schematically showing a relationship between a light-condensing film and a holder according to the first embodiment of the present invention.
FIG. 4 is a plan view schematically showing a relationship between a light-condensing film and a holder according to a second embodiment of the present invention.
FIG. 5 is a plan view schematically showing a light-collecting film according to a third embodiment of the present invention.
FIG. 6 is a plan view showing a modification of the third embodiment.
FIG. 7 is an exploded side view schematically showing a conventional example of a backlight device for a liquid crystal display element.
FIG. 8 is a plan view schematically showing an optical film according to the conventional example.
FIG. 9 is a plan view schematically showing a holder according to the conventional example.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 optical unit 10 light guide plate 20 optical film laminate 21 light diffusion film 22, 23 light condensing film 221, 222 side edge 223 surface 224 back surface 225, 226 corner portion 22a, 22b protruding piece 22c, 22d notch 24 brightness increasing film 30 light reflection sheet 40 holder 41 storage recesses 43a, 43b recess P liquid crystal panel AL diagonal line CL1 horizontal center line CL2 vertical center line XL optical axis

Claims (4)

In a backlight device for a liquid crystal display element including a light source disposed on a side opposite to the observation surface of the liquid crystal display element and an optical film disposed in a light irradiation path from the light source to the liquid crystal display element,
On each of two opposing sides of the optical film, one positioning mark of the same shape and the same size is formed at a point symmetrical position with a center point at the intersection of the vertical center line and the horizontal center line of the optical film. A backlight device for a liquid crystal display element, comprising: In a backlight device for a liquid crystal display element including a light source disposed on a side opposite to the observation surface of the liquid crystal display element and an optical film disposed in a light irradiation path from the light source to the liquid crystal display element,
On two opposing sides of the optical film, a plurality of pairs of positioning marks are formed at point-symmetric positions with the center point at the intersection of the vertical center line and the horizontal center line of the optical film. Is a backlight device for a liquid crystal display element, wherein positioning marks formed on the same side are asymmetric with respect to a center point of the side. 3. The backlight device for a liquid crystal display device according to claim 1, wherein the positioning mark comprises a projecting piece projecting from a side of the optical film. 3. The backlight device for a liquid crystal display device according to claim 1, wherein the positioning mark is formed by a cutout obtained by cutting off a part of a side of the optical film.

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