JP2008181692A - Backlight unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hold an optical sheet without increasing constituent members and the number of manufacturing steps. <P>SOLUTION: A backlight unit is provided with a light source 106, a light-guide body 105 for guiding the light of the light source 106, an optical sheet 103 arranged on the upper face of the light-guide body 105, a casing 108 having a recessed part for storing them, and a frame body 101 arranged at the opening of the casing 108. Particularly, the optical sheet 103 has a peripheral edge protruded from the side face of the light-guide body 105. A protrusion 102 formed on the lower face of the frame body 101 is abutted on the upper-face side of the peripheral edge. The backlight unit has a gap between the lower face of the peripheral edge bent to the bottom-face side of the casing 108 by the protrusion 102, and the bottom face of the recessed part in the casing 108. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a backlight structure used for a liquid crystal display module and the like, and more particularly to a backlight unit structure in which a backlight and optical sheets are accommodated in a backlight chassis.

  FIG. 3 is a plan view of the backlight unit 10 shown as the background art of the present invention viewed from the light emission observation surface side. The backlight unit 10 includes a backlight chassis 1 that is a housing that houses a light source and a light guide plate that guides light from the light source, and a frame 11 that is attached to the upper surface of the backlight chassis 1. The frame body 11 is rectangular in appearance and has an opening 14 corresponding to the emission observation surface.

  FIG. 4 is an enlarged view of a cross section of the peripheral portion of the backlight chassis 1, that is, a cross section taken along line AA of FIG. In the backlight chassis 1, a reflective sheet 6, a light guide plate 5 including a light source (not shown), and an optical sheet unit 4 for optically controlling light emitted from the light guide plate are stacked in order from the bottom. Are stored. The optical sheet unit 4 has a structure in which two prism lens sheets 42 and 43 are laminated on a diffusion sheet 41.

  On the lower surface of the frame 11 on the optical sheet portion 4 side, a plurality of cone-shaped projections 2 are arranged in a plurality of rows along each side of the frame forming the opening 14. ing. In FIG. 3, the projection group is drawn with a solid line only on the short side of the frame, and the projection group on the other side is omitted by being shown with a dotted line. The projection group 2 can be easily formed by drawing the frame body 11.

  As shown in FIG. 4, the present backlight unit closes the gap 13 generated between the frame body 11 and the upper surface of the optical sheet portion 4 with the projection group 2 of the frame body 11, thereby providing a gap 13 from the outside. It is intended to prevent foreign objects from entering. Preferably, in order to completely close the gap, the projection group 2 is contacted so as to press the optical sheet. In addition, by providing the projection group in this way, the optical sheet portion 4 is firmly pressed toward the light guide plate 5, and vibration sound due to the optical sheet shifting can be eliminated.

JP 2001-210128 A.

  However, since the backlight unit of the prior art sufficiently obtains an elastic force for pressing the optical sheet, the distance between the protrusion when the optical sheet is not in between and the upper surface of the light guide is larger than the thickness of the optical sheet part. Is also designed to be smaller. When the backlight unit is formed, the optical sheet portion having a thickness larger than the distance between the protrusion and the upper surface of the light guide is deformed in the thickness direction and interposed between the protrusion and the light guide. Fixed. At this time, the frame floats to the upper surface side due to the repulsive force of the deformed optical sheet, and the thickness of the entire backlight unit increases. In addition, while taking into account the increase in the thickness of the entire backlight unit and the increase in thickness due to the thermal expansion of the optical sheet, the dimensions of each component are adjusted to prevent the thickness of the entire backlight unit from increasing. It is difficult to design.

  Further, the thickness of the entire backlight unit is made constant. For example, the optical sheet portion is fixed to a gap formed between the lower surface of the frame and the upper surface of the optical sheet portion via an elastic member such as a spring. If it does in this way, the elastic member required for fixation of an optical sheet part and the component related also will increase. Furthermore, the number of manufacturing steps of the backlight unit will increase.

  Therefore, an object of the present invention is to provide a backlight unit that is thinned without increasing the number of constituent members and the number of manufacturing steps of the backlight unit.

  In order to achieve the above object, a backlight unit according to the present invention includes a light source, a light guide that guides light of the light source, an optical sheet portion disposed on the upper surface of the light guide, In a backlight unit including a housing having a concave portion to be accommodated and a frame body disposed in an opening of the housing, the optical sheet portion has a peripheral portion protruding from a side surface of the light guide. And a protrusion disposed on the lower surface of the frame body is abutted against the upper surface side of the peripheral portion, and the lower surface of the peripheral portion is bent toward the bottom surface side of the housing by the protrusion, and the housing It is a backlight unit characterized by having a gap between the bottom surface of the recess.

  An inner frame is disposed on the bottom surface of the recess between the side surface of the light guide and the inner wall surface of the housing, and a part of the peripheral edge of the optical sheet portion is in contact with the upper surface of the inner frame. preferable. Furthermore, it is preferable to have the said clearance gap between the lower surface of the said peripheral part in the side surface side of the said light guide, and the upper surface of the said inner frame.

  It is preferable that the contact surface of the protrusion that is in contact with the upper surface side of the optical sheet portion is a curved surface that is convex toward the optical sheet portion.

  It is preferable that the protrusion is provided on the shortest side among the sides forming the outer shape of the frame.

  It is preferable that the said peripheral part has a convex part protruded from the side surface of the said optical sheet part, and the convex part is accommodated in the recessed part provided in the upper surface of the said inner frame.

  The present invention can provide a thin backlight unit without increasing the number of constituent members of the backlight unit and the number of manufacturing steps.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the backlight unit for embodying the technical idea of the present invention, and the present invention does not limit the backlight unit to the following.

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

  A light source, a light guide that guides the light of the light source, an optical sheet disposed on the top surface of the light guide, a housing having a recess for housing them, and an opening of the housing In order to obtain a thin backlight unit without increasing the number of components and manufacturing steps of the backlight unit, the present inventor has made various studies. . Then, a peripheral portion protruding from the side surface of the light guide is provided on the optical sheet portion, a protrusion disposed on the lower surface of the frame body is abutted against the upper surface side of the peripheral portion, and the protrusion is used to The problem has been solved by providing a gap between the lower surface of the peripheral edge bent to the bottom surface side and the bottom surface of the recess of the housing.

  That is, the present invention has a particularly important configuration in which a gap is provided between the lower surface of the optical sheet portion bent by the protrusion being abutted against the upper surface side and the bottom surface of the concave portion of the housing. That is, according to the present invention, the peripheral portion of the optical sheet that protrudes from the upper surface of the light guide is bent by the protrusion of the frame, and the restoring force of the optical sheet is viewed as the elastic force of the spring in the thickness direction of the optical sheet portion. A backlight unit that holds and fixes the optical sheet. Thereby, the optical sheet can be fixed without requiring an elastic member such as a spring, and a backlight unit can be obtained in which the number of manufacturing steps is reduced by reducing the number of components.

  FIG. 1 is a perspective view in which the backlight unit 100 according to the present embodiment is disassembled for each constituent member of the backlight unit 100 and each constituent member is viewed from the upper surface side of the frame body 101. Note that the optical sheet portion 103 and the light guide 105 are drawn in a transparent manner for easy understanding of the relationship with other components. FIG. 2 is a cross-sectional view taken along the line XX of FIG. 1 when the backlight unit 100 of the present embodiment is configured.

  An outline of the backlight unit 100 according to the present embodiment will be described based on FIGS. 1 and 2. The backlight unit 100 of the present embodiment includes a light source 106, a light guide body 105 that guides light from the light source 106, and A housing 108 that houses the optical sheet portion 103 and a frame body 101 that is attached to an opening of the housing 108 are provided. The frame body 101 has an opening that forms a light emitting surface, and the upper surface of the optical sheet portion 103 is exposed in the opening. Hereinafter, the backlight unit 100 of this embodiment will be described in more detail.

  In the concave portion of the housing 108, a light source 106 disposed along the side wall of the concave portion, a light guide 105 that guides light from the light source 106 facing the light incident surface in order from the bottom surface of the concave portion, An optical sheet portion 103 for optically controlling the light emitted from the light guide 105 is stacked and stored. The optical sheet portion 103 of this embodiment includes a diffusion sheet, a first prism lens sheet, and a second prism lens sheet in which the arrangement direction of the prisms is different from that of the first prism lens sheet in order from the light guide side. Are stacked. These diffusion sheets, the first prism lens sheet, and the second prism lens sheet have shapes corresponding to the size and shape of the light exit surface of the light guide.

  The optical sheet part arrange | positioned at the upper surface of a light guide has the peripheral part protruded from the side surface of a light guide. Moreover, the protrusion arrange | positioned at the lower surface of a frame is abutted on the upper surface side of the said peripheral part. Further, there is a gap between the lower surface of the peripheral edge bent toward the bottom surface side of the housing by the protrusion and the concave bottom surface of the housing. In addition, if this clearance gap is between the lower surface of a peripheral part and the recessed part bottom face of a housing | casing, the inner frame etc. which are arrange | positioned at the recessed part bottom face of a housing | casing WHEREIN: The lower surface of a peripheral part and the recessed part bottom face of a housing | casing It may be provided between another member interposed therebetween.

  The frame of this embodiment is disposed on the optical sheet portion, and has a protrusion on the lower surface on the side of the optical sheet portion. This protrusion is preferably provided on the shortest side of the sides forming the outer shape of the frame. The outer shape of the frame is not limited to a quadrangle, and can be selected from polygons having various shapes. For example, as shown in the drawing, the outer edge and the opening of the frame of the present embodiment are rectangles composed of a short side, a short side opposed to the short side, and a long side connecting the sides and facing each other. Thus, when the outer shape of the frame is rectangular, the protrusion can be provided on the long side of the long side or the short side of the rectangle, but it is more preferably provided on the short side. This is because the number of protrusions can be reduced and deformation due to thermal expansion of the optical sheet can be relaxed in the long side direction of the frame.

  The contact surface of the protrusion with the upper surface of the optical sheet portion is preferably a curved surface convex in the direction of the optical sheet portion. Thereby, the damage to the optical sheet part by a protrusion can be eliminated. The outer shape of the protrusion is preferably a track shape, an oval shape, or an ellipse shape that includes a pair of semicircles and a pair of straight lines facing each other when viewed from the front. For example, the protrusion in this embodiment has a track shape composed of a pair of semicircles and a pair of straight lines facing each other when viewed from the front direction, and the longitudinal direction of the protrusion is made to coincide with the short side direction of the frame. is there. Moreover, the external shape of the vertical cross section of the protrusion in the longitudinal direction and the short direction is a dome shape. The longitudinal direction of the projection having such a shape is preferably matched with the short side direction of the frame having a rectangular outer shape. Thereby, compared with what makes the longitudinal direction of protrusion correspond to the long side direction of a frame, it can hold down more firmly so that an optical sheet may not move to the long side direction of a frame.

  In the present embodiment, the number and shape of the protrusions arranged on the lower surface of the frame body may be any form as long as the optical sheet portion is prevented from rattling. Similar to the form of the single protrusion described above, the surface including the entire protrusion group that is an aggregate of a plurality of protrusions is preferably a curved surface that is convex in the direction of the optical sheet portion. Thereby, the damage to the optical sheet part by a protrusion can be eliminated. Moreover, it is preferable that the longitudinal direction of the shape when the projection group is viewed is matched with the short side direction of the frame. Thereby, compared with what makes the longitudinal direction of a projection group correspond with the long side direction of a frame, it can hold down more strongly so that an optical sheet may not move to the long side direction of a frame. Moreover, it is preferable that the general shape including the entire protrusion group is a circle or an ellipse when viewed from the front.

  The shape of the protrusion or protrusion group is preferably such that the cross-sectional area parallel to the lower surface of the frame body gradually decreases from the lower surface of the frame body toward the upper surface direction of the optical sheet portion. By reducing the upper end of the protrusion abutted against the upper surface side of the optical sheet portion, it is possible to suppress the generation of wrinkles due to the protrusion pressing the sheet. Moreover, if the cross-sectional area of the protrusion on the lower surface side of the frame is reduced, the strength of the protrusion is reduced and the pressure on the optical sheet portion of the frame is insufficient. For example, the shape of the protrusion or the protrusion group can be a cone shape such as a mountain shape, a cone, a triangular pyramid, or a quadrangular pyramid.

  The height of the protrusion is appropriately adjusted in consideration of the size of the backlight unit and the physical properties (thickness and elasticity) of the optical sheet so that the deflection of the peripheral edge of the optical sheet necessary for fixing can be obtained. This is because if the height of the protrusion is too low, the optical sheet portion cannot be sufficiently pressurized, and if the height of the protrusion is too high, the optical sheet portion is greatly deformed.

  The backlight unit of this embodiment can further include an inner frame having an opening for accommodating the light guide. The inner frame is disposed between the light guide and the casing, so that the light source and the light guide can be held at predetermined positions of the casing.

  In the backlight unit of this embodiment, for example, an inner frame is disposed on the bottom surface of the recess between the side surface of the light guide and the inner wall surface of the housing, and a part of the peripheral edge portion of the optical sheet portion bent by the protrusion is disposed on the inner side. It abuts on the upper surface side of the frame. Accordingly, the optical sheet is more firmly formed in a part of the peripheral edge abutted on the upper surface side of the inner frame as compared with the form in which the lower surface of the peripheral edge directly faces the bottom surface of the recess without providing the inner frame. Part can be held. Furthermore, the height of the side surface of the light guide body from which the peripheral edge protrudes from the bottom surface of the concave portion is made higher than the height from the bottom surface of the concave surface of the inner frame upper surface, so The above-described gap is provided between the upper surface of the light guide body and the side surface of the light guide so as to gradually increase. As a result, compared to a form in which the lower surface of the peripheral part directly faces the bottom surface of the recess without having an inner frame, or a form having a gap between the entire lower surface of the peripheral part of the optical sheet part and the upper surface of the inner frame. The optical sheet portion can be more firmly held by a part of the peripheral edge portion that is in contact with the upper surface side of the inner frame.

  Note that the position of the gap can be changed by adjusting the height of the side surface of the light guide from the bottom surface of the recess and the height from the bottom surface of the recess of the upper surface of the inner frame. That is, the height of the side surface of the light guide from the bottom surface of the recess is made lower than the height from the bottom surface of the recess on the top surface of the inner frame. Thus, instead of providing the gap between the lower surface of the peripheral portion on the side surface of the light guide and the upper surface of the inner frame, the gap is provided between the lower surface on the end surface side of the optical sheet portion and the upper surface of the inner frame. It is also possible to bring the peripheral portion and the upper surface of the light guide into contact with each other on the side surface of the light guide. However, in order to more firmly fix the optical sheet portion, as described above, the height from the bottom surface of the concave portion on the side surface of the light guide is set higher than the height from the bottom surface of the concave portion on the upper surface of the inner frame. It is preferable that the gap be gradually increased from the end surface to the side surface of the light guide.

  In the backlight unit having such an inner frame, the shape of the upper surface of the side wall that forms the opening of the inner frame can be used for fixing the optical sheet portion. That is, the peripheral edge itself of the optical sheet portion has a convex shape, or a convex portion that protrudes from the side surface of the light guide is provided on a part of the peripheral edge, and the convex portion is provided in the concave portion provided on the upper surface of the side wall of the inner frame The optical sheet portion is held not only in the direction perpendicular to the main surface by the protrusions but also from a direction parallel to the main surface. In addition, when it is set as the backlight unit provided with the inner frame, the clearance gap which is the characteristic of this invention is provided also between the lower surface of the said convex part, and the upper surface of the side wall of an inner frame. Further, the projection of the frame body may be abutted against the upper surface side of the convex portion, or may be abutted against the upper surface of the peripheral edge portion having the convex portion. Thereby, an optical sheet part can be fixed with the uneven | corrugated shape of an optical sheet part and a flame | frame.

  In addition, in this form, the optical sheet part fixed is not limited to the form which is all the optical sheets which comprise an optical sheet part, The one part optical sheet which comprises an optical sheet part may be sufficient.

  The frame and the housing may be fixed using an adhesive sheet or an adhesive, may be fixed by fitting, or may be fixed by providing a shape that can be fitted to each other. As an example of the latter, by providing a side wall having a larger outer periphery than the side wall of the housing on the frame, and fitting the uneven shape formed on the side wall of the frame with the uneven shape of the side wall portion of the housing, A backlight unit can be obtained by fitting and fixing a frame body around the side wall of the housing.

  Although not shown, the liquid crystal display panel is mounted on the upper surface of the frame, and a liquid crystal display module in which a backlight unit and a liquid crystal display panel are combined is configured. Hereinafter, each structure of this form is explained in full detail.

(Light source 106)
The light source in this embodiment is a light emitting member that emits light that can be incident on a light guide, such as a semiconductor light emitting element such as a light emitting diode or a semiconductor laser, a cold cathode ray tube, or a composite light source that is selected and combined variously. Say. Regarding the arrangement of the light source on the light guide, an edge light system in which a light source is arranged on the side end face of the light guide may be used, or a direct type system in which a light source is arranged on the lower surface of the light guide.

  Hereinafter, although a light emitting diode is demonstrated, it is not limited to this. The light emitting diode can be variously selected depending on the dominant wavelength of light emitted from the semiconductor layer. In particular, light-emitting diodes that emit white mixed light are widely used. Such light-emitting diodes include various combinations of LED chips that emit RGB colors, light-emitting diodes including LED chips, and phosphors that emit light excited by light emitted from the LED chips. Things. An LED chip capable of emitting blue light can emit light with high brightness by using, for example, a gallium nitride compound semiconductor.

  In addition, the light emitting diode in this embodiment includes a package serving as a support for the LED chip. The electrode disposed on the support and the electrode of the LED chip are electrically connected by a conductive wire such as a gold wire or a conductive paste such as an Ag-containing epoxy resin. The semiconductor element and the conductive wire are covered with a light-transmitting resin such as an epoxy resin or a silicone resin, and are protected from the external environment.

  The package used in this embodiment is preferably one in which an LED chip can be disposed at the bottom of the recess, and various resins such as epoxy resin, silicone resin, acrylic resin, PBT (polybutylene terephthalate), liquid crystal polymer, and aromatic nylon are used. And is preferably formed.

  The package may be a ceramic package obtained by firing a ceramic material. Since the ceramic package is superior in heat resistance and light resistance as compared to a package made of a resin material, a high-output and highly reliable semiconductor light-emitting device can be obtained.

  The package is preferably filled with an LED chip and a translucent resin electrically connected to the lead electrode. Here, the translucent resin that covers the LED chip may contain a fluorescent material as necessary.

The fluorescent substance contained in the translucent resin that covers the LED chip converts the wavelength of the light of the LED chip. That is, the fluorescent material absorbs at least a part of the light of the LED chip and emits light having a different wavelength. Here, the phosphor is preferably a phosphor that converts light from the LED chip to a longer wavelength side. In the case where the light from the LED chip is high-energy short-wavelength visible light, perylene derivatives that are organic phosphors, ZnCdS: Cu, and YAG: Ce that is a kind of aluminum oxide phosphor (for example, YAlO ₃ : Ce). , Y ₃ Al ₅ O ₁₂ : Ce), and inorganic phosphors such as nitrogen-containing CaO—Al ₂ O ₃ —SiO ₂ activated by Eu and / or Cr. In particular, the YAG: Ce phosphor absorbs part of the blue light from the LED chip depending on its content and emits yellow light that is a complementary color. Can be formed relatively easily.

(Mounting board)
The mounting board is for mounting and fixing and arranging a light source, and is provided with a conductor wiring for supplying power to the light source. For example, it can be suitably formed by a glass epoxy substrate on which a conductive pattern made of copper foil or the like is formed, a flexible substrate, or a metal body bonded with an insulating resin. Or it can be set as the board | substrate with high heat dissipation by which conductor wiring was given to the metal material which consists of aluminum and copper via the insulating material. Moreover, it is preferable that a mounting board | substrate is closely_contact | adhered and arrange | positioned through a heat conductive member like a heat dissipation sheet.

(Light guide 105)
The light guide in this embodiment refers to a light which can guide light from a light source incident from a part of an end face by utilizing internal reflection and emit light in a desired shape from a predetermined light exit surface. It is an optical member. Therefore, depending on the desired shape of the light emitting surface, various shapes such as a needle shape of a meter needle and a plate shape usable as a liquid crystal backlight light source can be taken. The light guide has translucency in order to efficiently emit light from the light emitting diode or light obtained by wavelength conversion of the light from the light emitting surface. As a material for such a light guide, various materials such as acrylic resin, epoxy resin, and glass are preferably exemplified.

(Case 108)
The housing in this embodiment has a recess that accommodates a mounting substrate on which a light source is disposed, a light guide, and an optical sheet portion, and a frame is disposed in the opening of the recess, and these members It is a member holding. Note that the optical sheet portion of the present embodiment may have a structure in which various layers selected from a diffusion sheet, a prism lens sheet, a deflection sheet, and the like are stacked. In addition, the number of sheets and the order in which various sheets are stacked are appropriately adjusted for each sheet constituting the optical sheet unit in consideration of the optical characteristics of the backlight unit.

  As the material for the housing, various materials such as resins and metals containing various light diffusing agents are preferably exemplified. In particular, in consideration of heat dissipation and light reflection of a light emitting diode that generates heat, metals such as nickel, iron, copper, and aluminum, and various alloys such as stainless steel are more preferably used. The size and shape of the housing can be variously selected according to the size and shape of the member to be accommodated.

(Frame body 101)
The frame body in this embodiment is a member that is provided on the opening side of the housing and has a protrusion that presses the optical sheet portion disposed on the light guide housed in the housing. In particular, the overall shape of the frame in this embodiment is rectangular, and when the backlight unit is configured, the upper surface of the optical sheet portion is exposed from the opening of the frame to form a light emitting surface.

  The frame material is made of metal such as nickel, iron, copper, aluminum, stainless steel, etc. considering the elastic force required to hold down the optical sheet, heat dissipation from the light source that generates heat, and light reflection. Various alloys are more preferably used. The size and shape of the frame can be variously selected according to the size and shape of the member to be accommodated. In particular, the frame in this embodiment is preferably a rectangle having a ratio of the long side to the short side of 1.6 to 1.7. By forming such a rectangle, the optical sheet in the long side direction is sufficiently pressed so that the optical sheet does not rattle on the short side by providing a protrusion on the short side rather than the long side of the rectangle. The deformation due to thermal expansion of the optical sheet can be alleviated, and wrinkles of the optical sheet can be eliminated.

(Inner frame 104)
The inner frame in this embodiment has an opening that accommodates the light guide, and is disposed between the light guide and the housing, thereby holding the light source and the light guide at a predetermined position of the housing. It is a member to do. The inner frame can also be a support member that holds the light source at a predetermined location. The shape of the inner frame may be various shapes according to the shape of the housing or the light guide. The inner frame in this embodiment has at least a recess or a through hole having an opening that can accommodate the light guide. The size and shape of the recess or the through hole are appropriately adjusted according to the size, shape, and number of light guides to be accommodated. Further, the thickness of the side wall forming the opening of the inner frame is smaller than the size of the gap formed by the side surface of the light guide and the inner wall surface of the recess of the housing. Accordingly, the inner frame can be fitted into a gap formed by the side surface of the light guide and the inner wall surface of the recess of the housing, and the light guide and the inner frame can be accommodated in the recess of the housing.

  The inner frame preferably has a light diffusing agent such as calcium carbonate, aluminum oxide or titanium oxide or a white pigment at least on the inner wall surface of the side wall forming the opening. Such a side wall portion of the inner frame reflects light from the light source toward the incident surface of the light guide or reflects light emitted from the side surface of the light guide toward the light guide. It can re-enter the light body.

  As the material of the inner frame, a material having a lower thermal conductivity than the material of the mounting substrate is selected. For example, an insulating material such as polycarbonate, polyether ether ketone, or fluorine-based resin having excellent mechanical strength can be used. Furthermore, the inner frame can also be formed by injection molding with a resin material containing a light diffusing agent such as calcium carbonate, aluminum oxide or titanium oxide.

  Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.

  The fixing structure of the optical sheet part of the present embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view showing a backlight unit having an optical sheet fixing structure according to the present embodiment. FIG. 2 is a cross-sectional view taken along the line XX of FIG. 1 when the backlight unit of this embodiment is configured.

  The backlight unit 100 of this embodiment includes a light source 106 in which a light emitting diode that emits white light is arranged on a mounting substrate, and a light guide plate 104 made of acrylic resin that guides light from the light source 106 from the side. A stainless steel housing 108 having a recess for housing the light source 106, the light guide plate 104 and the optical sheet portion 103, and a stainless steel frame 101 attached on the side wall portion of the housing 108 forming the recess, Is provided. The frame body 101 has an opening that forms a light emitting surface, and a part of the upper surface of the optical sheet portion 103 is exposed in the opening. Further, the backlight unit 100 of the present embodiment includes a reflection sheet 107 for reflecting the light of the light guide plate 105 toward the light emitting surface between the lower surface of the light guide plate 105 and the bottom surface of the recess of the housing 108. Hereinafter, the backlight unit 100 of the present embodiment will be described in more detail.

  The optical sheet portion 103 for optically controlling the light emitted from the light guide plate 105 is disposed on the light extraction surface of the light guide plate 105. The optical sheet portion 103 of this embodiment includes, in order from the light guide plate 105 side, a diffusion sheet, a first prism lens sheet, and a second prism lens in which the first prism lens sheet is different in the arrangement direction of the prisms. Sheets are stacked.

  As shown in the figure, a protrusion 102 is provided on the lower surface of the frame body 101 disposed on the optical sheet portion 103, and this protrusion 102 is abutted against the upper surface side of the peripheral portion of the optical sheet portion 103. The optical sheet portion 103 is fixed. That is, the peripheral portion of the optical sheet portion 103 protruding from the upper surface of the light guide plate 105 is bent by abutting the protrusion 102 on the lower surface of the frame body 101, and the light guide plate 105 and the housing 108 are on the lower surface side of the peripheral portion. The inner frame 104 and the projections 102 arranged between the inner wall surfaces of the body are provided with a margin so that the entire peripheral edge of the optical sheet portion 103 is not sandwiched. Specifically, by making the height of the upper surface of the inner frame 104 from the bottom surface of the concave portion lower than the height of the upper surface of the light guide plate 105, the gap between the upper surface of the inner frame 104 and the lower surface of the peripheral edge becomes the side surface of the light guide plate 105. It gradually increases toward the direction. Further, the surface of the protrusion 102 that abuts against the upper surface of the optical sheet portion 103 is a curved surface that is convex toward the optical sheet portion 103. In order to indicate the degree of bending of the optical sheet portion 103 by the protrusion 102, the upper surface of the peripheral edge portion of the optical sheet portion 103 is guided in the vertical direction passing through the contact point between the peripheral edge portion of the optical sheet portion 103 and the protrusion 102 of the frame body 101. A distance from the upper surface of the optical sheet portion 103 disposed on the main surface of the optical plate 105 is measured. The distance between the upper surface of the peripheral portion of the optical sheet portion 103 in this embodiment and the upper surface of the optical sheet portion 103 disposed on the main surface of the light guide plate 105 is 0.05 mm to 0.50 mm. .

  The protrusions 102 provided on the frame body 101 of the present embodiment are provided closer to the line that bisects the rectangular frame body in the longitudinal direction than the corners of the rectangular frame body 101 having an outer shape. Thereby, the optical sheet part 103 can be fixed firmly compared with what provides a protrusion near the corner | angular part of a rectangular frame.

  INDUSTRIAL APPLICABILITY The present invention is applicable to an in-vehicle liquid crystal display device or the like as a backlight that is resistant to vibration and is thinned, miniaturized, and reduced in power consumption.

FIG. 1 is a perspective view showing an embodiment of a backlight unit of the present invention. FIG. 2 is a cross-sectional view showing an embodiment of the backlight unit of the present invention. FIG. 3 is a top view of a conventional backlight unit. FIG. 4 is an enlarged view of a cross section taken along the line AA of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Backlight unit 101 ... Frame body 102 ... Protrusion 103 ... Optical sheet part 104 ... Inner frame 105 ... Light guide body 106 ... Light source 107 ... Reflective sheet 108 ... Case

Claims (6)

A light source, a light guide that guides light from the light source, an optical sheet portion disposed on the upper surface of the light guide, a housing having a recess for housing them, and an opening in the housing And a backlight unit comprising a frame body,
The optical sheet portion has a peripheral edge protruding from a side surface of the light guide,
A protrusion disposed on the lower surface of the frame body is abutted against the upper surface side of the peripheral edge, and the lower surface of the peripheral edge bent toward the bottom surface of the housing by the protrusion, and the bottom of the recess of the housing Backlight unit characterized by having a gap between them.   The inner frame is disposed on the bottom surface of the recess between the side surface of the light guide and the inner wall surface of the housing, and a part of the peripheral edge of the optical sheet portion is in contact with the upper surface of the inner frame. The backlight unit according to 1.   The backlight unit according to claim 2, wherein the gap is provided between a lower surface of the peripheral edge portion and a top surface of the inner frame on the side surface side of the light guide.   4. The backlight unit according to claim 1, wherein the contact surface of the protrusion that is in contact with the upper surface side of the optical sheet portion is a curved surface that protrudes toward the optical sheet portion. 5.   The backlight unit according to any one of claims 1 to 4, wherein the protrusion is provided on the shortest side among the sides forming the outer shape of the frame.   The said peripheral part has a convex part protruded from the side surface of the said optical sheet part, The convex part is accommodated in the recessed part provided in the upper surface of the said inner frame. The backlight unit described in.

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