JP4660162B2 - Optical film fixing device - Google Patents

Description

  The present invention relates to an optical film fixing device, and more particularly to an optical film fixing device suitable for fixing an optical film provided in a backlight of a liquid crystal display element.

  The transmissive / semi-transmissive liquid crystal display element includes a backlight as a backlight device for obtaining a good display even when the periphery is dark. The backlight is divided into a direct type and a side light (edge light) type depending on the arrangement of the light source, but in any case, in order to efficiently irradiate the liquid crystal display element with the light emitted from the light source, An optical film is disposed in the optical system.

  Optical films include light diffusion films and brightness enhancement films. Recently, viewing angle limiting (viewing angle adjustment) films have been developed, and these viewing angle limiting films are used in some models.

  The viewing angle limiting film is a film that can be displayed within a specific viewing angle range, but is not visible when it is out of the range. For example, it is used to protect privacy information in a mobile phone, and a car navigation system. In-vehicle monitors are used to prevent the monitor screen from being reflected on the windshield at night or when traveling in a tunnel. As a commercially available product, for example, there is a light control film “Vikuiti” (trade name) manufactured by 3M.

  By the way, the following problems arise when the viewing angle limiting film is included in the optical film of the backlight. Normally, this type of optical film is fixed to a backlight holder with, for example, a double-sided adhesive tape, but the viewing angle limiting film has a larger coefficient of thermal expansion than other optical films.

  For this reason, if the viewing angle limiting film is fixed with double-sided adhesive tape, etc., in applications such as in-vehicle equipment that may be placed in a high temperature state, the film swells at a high temperature, which may adversely affect the display. is there. In addition, since the brightness enhancement film falls into a category having a large coefficient of thermal expansion, the same problem is likely to occur particularly in the case of in-vehicle equipment.

  Accordingly, an object of the present invention is to fix an optical film having a large coefficient of thermal expansion, such as the above-mentioned viewing angle limiting film, to the holder so that no undulation or the like occurs during the thermal expansion. It is in.

To solve the above problems, the invention according to claim 1, the optical film of the rectangular shape, in the fixing device of the optical film to be fixed to the holder as acceptable dimensional changes due to thermal expansion of its corners of the holder A support body which is made of a rubber elastic body capable of yielding deformation by the expansion force of the optical film and elastically supports corners of the optical film on the upper surface of the base film. It is characterized by being provided.

  The invention according to claim 2 is the above-mentioned claim 1, wherein the support is a pair of supports that abut against two adjacent sides sandwiching the corner of the optical film except for the apex of the corner of the optical film. It is characterized by having a piece.

The invention according to claim 3 is the above-mentioned claim 1, wherein the top portion of the corner portion of the optical film is provided with a head projecting outward from two adjacent sides sandwiching the corner portion, the support is arranged along two sides adjacent sandwiching the corner portion with the head of the optical film, a pair of support pieces are separated at the portion corresponding to the apex portion of the corner And the two adjacent sides of the optical film are in non-contact with the support pieces, and the head of the optical film is in contact between the opposite ends of the support pieces. It is said.

  According to a fourth aspect of the present invention, there is provided the optical film according to any one of the first to third aspects, wherein the optical film is an optical film for a sidelight type backlight using a light source as a cold cathode tube, and the base Is characterized in that a holding hole for holding the electrode terminal portion of the cold cathode tube is formed.

  According to the first aspect of the present invention, the optical film is expanded by supporting the corners of the optical film by the support made of a rubber elastic body capable of yield deformation by the expansion force of the optical film. However, since the elongation corresponding to the expansion is absorbed by the support, no waviness or the like occurs in the optical film.

  Further, according to the invention described in claim 2, by excluding the apex portion of the corner portion of the optical film, the two adjacent sides sandwiching the corner portion are supported by the respective support pieces. Since the apex portion of the corner portion is in a free (unconstrained) state, it can cope with any elongation in the longitudinal direction (X direction) and lateral direction (Y direction) of the optical film.

  According to the invention described in claim 3, each support piece is provided at the apex portion of the corner of the optical film with respect to the pair of support pieces separated at the portion corresponding to the apex portion of the corner of the optical film. The head is in contact with the opposite end of the optical film, and the two adjacent sides of the optical film are brought into a non-contact state with respect to each support piece. It is possible to cope with any elongation in the (X direction) and lateral direction (Y direction).

  According to the fourth aspect of the present invention, in the sidelight-type backlight having the light source as a cold cathode tube, the cold cathode tube can be securely fixed by using a base placed at the corner of the holder. it can.

  Next, some embodiments of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited thereto. FIG. 1 is an exploded perspective view of a backlight 2 arranged on the back side of the liquid crystal display panel 1, and the present invention will be described by taking this as an example.

  The backlight 2 shown in FIG. 1 is a side light type and includes a light guide plate 21 made of, for example, polycarbonate resin. Although not shown, a light source is disposed along a predetermined side surface of the light guide plate 21. The light source is selected according to the size of the liquid crystal display panel 1. For example, a light emitting diode is used for a small-sized device such as a mobile phone, and a larger screen size is used for a medium-sized device such as an in-vehicle monitor. For this, a cold cathode tube is preferably used.

  A light reflection sheet 22 is disposed on the bottom surface of the light guide plate 21. On the upper surface of the light guide plate 21 (light irradiation surface with respect to the liquid crystal display panel 1), an optical film laminate 23 is disposed. In this example, the optical film laminate 23 includes a light diffusion film 24, a brightness enhancement film (prism film) 25, and a viewing angle limiting film 26 in order from the bottom, and the viewing angle limiting film 26 is disposed on the top. Is done.

  Since the light guide plate 21 has a rectangular shape, the optical films are also stacked in a rectangular shape and stored in the holder 3. Usually, the holder 3 is made of synthetic resin, but may be made of metal. In fixing the optical film in the holder 3, since the viewing angle limiting film 26 has a particularly high coefficient of thermal expansion as described above, the fixing device 4 according to the present invention is used.

  The fixing device 4 is arranged at the corner of the holder 3. In the example of FIG. 1, they are arranged at four corners, but may be arranged at two corners in a diagonal positional relationship. In FIG. 1, only the shape of the base portion included in the fixing device 4 is shown for the convenience of drawing, but a specific configuration example is shown in FIGS. 2 to 4.

  First, the fixing device 4A according to the first embodiment will be described with reference to the perspective view of FIG. The fixing device 4A includes a base 41 and a support body 42 formed on the upper surface side thereof. The base 41 and the support 42 are preferably formed integrally from a rubber elastic body.

  As the rubber elastic body, chloroprene rubber, acrylic rubber, whose elastic force is adjusted so as to be easily deformed by the expansion force of the optical film (in this example, the viewing angle limiting film 26 having a particularly large thermal expansion coefficient), Urethane rubber, fluororubber, silicone rubber and the like can be exemplified, but silicone rubber having excellent heat resistance is preferable for use in in-vehicle devices exposed to high temperatures.

  Since the base 41 is disposed at the corner of the holder 3 so as to be applied to the corner of the light guide plate 21, it is formed as a substantially L-shaped block. The thickness in the height direction is substantially equal to the thickness of the light guide plate 21, and the bottom surface of the base 41 is a grommet (both illustrated) that is forcibly fitted in the engagement groove formed in the bottom wall of the holder 3. Is not formed).

  In this example, a holding hole 41 a for fitting and holding an electrode terminal of a cold cathode tube as a light source (not shown) with respect to the light guide plate 21 is formed in the end surface of the base 41. According to this, the cold cathode tube can be reliably fixed to the light incident surface of the light guide plate 21 using the fixing device 4A.

  In the first embodiment, the support 42 includes an L-shaped partition 43 that rises along the inner surface of the base 41, and is included in the optical film laminate 23 at both ends of the partition 43. Support pieces 44 and 45 that support at least the corners of the viewing angle limiting film 26 among the optical films 24 to 26 are provided in series.

  Assuming that the apex of the corner of the viewing angle limiting film 26 is A and the two adjacent sides sandwiching the apex A are 26a and 26b, the support pieces 44 and 45 are in contact with the adjacent two sides 26a and 26b. In this case, the projecting dimension is such that the apex portion A of the corner does not contact the partition part 43.

  Further, convex stoppers 44a and 45a are integrally formed on the upper edge sides of the support pieces 44 and 45 to engage with the adjacent two sides 26a and 26b and prevent the viewing angle limiting film 26 from coming off. Yes. If the support pieces 44 and 45 are soft and the sides 26a and 26b of the viewing angle limiting film 26 can bite into the support pieces 44 and 45, it is not necessary to provide the convex stoppers 44a and 45a.

  As shown in FIG. 1, the fixing device 4A is preferably arranged at the four corners of the holder 3, and the viewing angle limiting film 26 has its four corners in contact with the support pieces 44 and 45 of each fixing device 4A. In the holder 3.

  According to this, when the viewing angle limiting film 26 expands in a high temperature environment, in FIG. 2, the extension in the vertical direction (X direction) is absorbed by the bending of one support piece 45, and the horizontal direction (Y Direction) is absorbed when the other support piece 44 is bent, and the viewing angle limiting film 26 is greatly expanded to be held by each fixing device 4A without causing undulation or the like. .

  Similarly, the expansion of another optical film, for example, the brightness enhancement film 25 can also be absorbed by the fixing device 4A. In addition, the fixing device 4A may be disposed at least at two corners in the diagonal position relationship of the holder 3 (the same applies to each embodiment described later).

  Next, the fixing device 4B according to the second embodiment shown in FIG. 3 will be described. Also in this fixing device 4B, the support body 42 includes a pair of support pieces 441 and 451 formed in a convex curve shape. In this case, the support pieces 441 and 451 are connected at one end to each other end. The side is formed to open at a predetermined angle. Let the connecting part be J.

  The opening angle on the other end side is such that when the two adjacent sides 26a and 26b (see FIG. 2) of the viewing angle limiting film 26 are brought into contact with the support pieces 441 and 451, the apex portion A contacts the connecting portion J. The range is not to be. The support pieces 441 and 451 act in the same manner as in the first embodiment when the viewing angle limiting film 26 undergoes thermal expansion.

  Further, in this fixing device 4B, the support body 42 is arranged such that the connecting portion J is arranged at the corner on the outer side of the base 41, whereby the upper surface 41b of the base 41 is used as the corner portion mounting surface of the optical film. ing. That is, each corner of the light diffusion film 24, the brightness enhancement film 25, and the viewing angle limiting film 26 shown in FIG. 1 can be placed on the upper surface 41b of the base 41, thereby realizing more stable support of each optical film. Yes.

  Next, the fixing device 4C according to the third embodiment shown in FIG. 4 will be described. The fixing device 4C is also provided with a pair of support pieces 46 and 47 formed on the upper surface 41b of the base 41. In this case, the support pieces 46 and 47 are formed in a rib shape of a vertical plate and each one end 46a thereof. 47a are formed along the outer edge of the base 41 so as to face each other at the outer corner of the base 41, for example.

  The ends 46a, 47a of the support pieces 46, 47 are cut off, and the outer corners of the base 41 are cut off, whereby the ends 46a, 47a of the support pieces 46, 47 are easily deformed as free ends. ing. Similarly to the first embodiment, the support pieces 46 and 47 are integrally provided with convex stoppers 46b and 47b that engage with the adjacent two sides 26a and 26b to prevent the viewing angle limiting film 26 from coming off. Is formed.

  On the other hand, in the third embodiment, a head portion 261 is formed at the apex portion of the viewing angle limiting film 26 so as to protrude outward from the adjacent two sides 26a and 26b. The head portion 261 has a size larger than a gap between the support pieces 46 and 47 so that both ends 46a and 47a can be in contact with each other. The shape may be arbitrary, such as a circle or a rectangle.

  The viewing angle limiting film 26 is arranged so that the head 261 abuts between the respective one ends 46a and 47a of the support pieces 46 and 47. However, since the head 261 projects outward, the two adjacent sides 26a. , 26b are placed at positions separated from the support pieces 46, 47.

  Accordingly, the elongation due to the thermal expansion of the viewing angle limiting film 26 is transmitted to the one ends 46a and 47a of the support pieces 46 and 47 via the head 261, and is released by the deformation thereof. Will not occur. This third embodiment can also be applied to the brightness enhancement film 25.

  In addition, you may arrange | position the support body 42 in this 3rd Embodiment along the inner edge of the base 41 like the said 1st Embodiment. Further, the support 42 in the first embodiment can be arranged along the outer edge of the base 41 as in the second and third embodiments.

  As described above, the present invention has been described with respect to the viewing angle limiting film included in the backlight for the liquid crystal display element. However, the present invention expands when heated to a high temperature other than this, for example, a colored film used in a lighting device, etc. This can also be applied to the case of fixing to the holder.

The disassembled perspective view which shows the backlight for liquid crystal display elements as an example of application of this invention. The perspective view which shows the fixing device of the optical film which concerns on 1st Embodiment of this invention. The perspective view which shows the fixing device of the optical film which concerns on 2nd Embodiment of this invention. The perspective view which shows the fixing device of the optical film which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Backlight 21 Light-guide plate 22 Light reflection film 23 Optical film laminated body 24 Light-diffusion film 25 Brightness enhancement film 26 View angle limit film 26a, 26b Two adjacent sides 261 Head 3 Holder 4, 4A-4C Fixing device 41 Base 41a Holding hole 42 Support body 44, 45, 441, 451, 46, 47 Support piece

Claims (4)

The optical film of rectangular shape, the fixing device of the optical film to be fixed to the holder as acceptable dimensional changes due to thermal expansion of its,
It has a base placed at the corner of the holder, and the upper surface of the base is made of a rubber elastic body that can yield and deform by the expansion force of the optical film, and elastically supports the corners of the optical film. A fixing device for an optical film, characterized in that a supporting body is provided.   The said support body is equipped with a pair of support piece contact | abutted with respect to two adjacent sides which pinch | interpose the corner | angular part except for the vertex part of the corner | angular part of the said optical film. Optical film fixing device. The apex portion of the corner of the optical film is provided with a head that projects outward from two adjacent sides sandwiching the corner,
The support is arranged along two sides adjacent sandwiching the corner portion with the head of the optical film, a pair of support pieces are separated at the portion corresponding to the apex portion of the corner And the two adjacent sides of the optical film are in non-contact with the support pieces, and the head portion of the optical film is in contact between the opposite ends of the support pieces. The optical film fixing device according to claim 1.   The optical film is an optical film for a sidelight type backlight having a light source as a cold cathode tube, and a holding hole for holding an electrode terminal portion of the cold cathode tube is formed in the base. The optical film fixing device according to any one of claims 1 to 3.

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