WO2008035485A1

WO2008035485A1 - Backlight unit and liquid crystal display device

Info

Publication number: WO2008035485A1
Application number: PCT/JP2007/060113
Authority: WO
Inventors: Tomoki Kubo
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-09-21
Filing date: 2007-05-17
Publication date: 2008-03-27

Abstract

A backlight unit (52) includes a single light-emitting fluorescent tube (41) and a single light path-changing block (BK) covering the fluorescent tube (41) and refracting incoming light to change its path. The light path-changing block (BK) has an entrance surface (11) through which light enters and an exit surface (12) from the back side of which the light exits. The exit surface (12) has a recessed cut (CT).

Description

Specification

Knocklight unit and liquid crystal display device

Technical field

The present invention relates to a backlight unit that emits light and a liquid crystal display device that uses light from a powerful backlight unit.

Background art

Conventionally, various backlight units for supplying light to a liquid crystal display panel (non-light emitting display panel) in a liquid crystal display device have been developed. The light source included in the area light type backlight unit or the like includes a hot cathode tube or a cold cathode tube fluorescent tube.

[0003] A hot cathode tube has electrodes made of filaments at both ends of the tube, a rare gas such as mercury or argon is sealed inside the tube, and a phosphor film is provided on the inner surface of the tube. Yes. Such a hot cathode tube collides the thermoelectrons emitted through the electrodes with the mercury atoms latent in the discharge tube. Then, the ultraviolet rays generated by the collision are converted into visible light by exciting the phosphor applied to the inner surface of the tube, and emitted outside the tube.

[0004] On the other hand, a cold cathode tube, like a hot cathode tube, converts ultraviolet light into visible light. However, the electrons emitted into the discharge tube are not thermal electrons. Therefore, a small electrode different from a relatively large filament can be used.

[0005] Problems arise when these cathode tubes are used in a thin-type and large-screen liquid crystal television (liquid crystal display device). For example, a hot cathode tube is large because it uses a relatively large filament. Therefore, when a large hot cathode tube is mounted on the knocklight unit to irradiate light on a large-screen liquid crystal display panel, the size of the knocklight unit itself increases. As a result, a thin liquid crystal television cannot be realized.

[0006] Also, the cold cathode tube has a lower luminance than the hot cathode tube although it is small because a relatively small electrode is used. Therefore, a relatively large amount of cold cathode tubes must be mounted on the knock light unit in order to irradiate the large-screen liquid crystal display panel with light. This will increase the size of the knocklight unit itself. As a result, a thin liquid crystal television cannot be realized as in the case of using a hot cathode tube. In addition, use of a large amount of cold cathode fluorescent lamp It also leads to an increase in the cost of the unit

[0007] In order to suppress an increase in the size and cost of a backlight unit that is powerful, it is necessary to increase the light emission amount of each fluorescent tube in the knocklight unit. If the fluorescent tube is a hot-cathode tube or a cold-cathode tube that emits a large amount of light (in other words, a fluorescent tube that emits light with high efficiency), the size of the knock-light unit can be reduced by reducing the number of fluorescent tubes. As a result, the cost of the backlight unit can be reduced.

[0008] However, when the number of fluorescent tubes in the knocklight unit is reduced by using fluorescent tubes that emit light with high efficiency, the fluorescent tubes 141. 141 are shown in the cross-sectional view of FIG. Spacing V increases. Then, although the upper part of the fluorescent tube 141 is bright, the upper part of the distance V ′ between the fluorescent tubes 141 and 141 becomes darker on the contrary (the upper part is the direction from the fluorescent tube 141 toward the reflection frame 142). Meaning the reverse direction). That is, there is a relatively large difference in brightness (light intensity unevenness) between the upper side of the fluorescent tube 141 and the upper side of the interval between the fluorescent tube tubes 141 and 141. Therefore, the display quality of the backlight unit 152 is degraded.

[0009] Further, when comparing the amount of light unevenness caused by fluorescent tubes emitting light with high efficiency and the amount of light unevenness caused by fluorescent tubes emitting light with normal efficiency, even if both fluorescent tubes have the same number, The unevenness in the amount of light caused by fluorescent tubes that emit light with high efficiency appears more prominently. For this reason, there is a limit to reducing the uneven light quantity of the knocklight unit while reducing the number of fluorescent tubes by using fluorescent tubes that emit light with high efficiency.

[0010] Therefore, Patent Document 1 discloses a backlight unit conceived to overcome such limitations. In the backlight unit of Patent Document 1, a groove is formed on the light receiving surface of the light guide plate that receives light from the fluorescent tube, and the light is scattered on the light output surface of the light guide plate (for example, having a V-shaped cross section). Groove (light quantity correction surface) is formed. In this case, the light from the fluorescent tube is scattered by passing through the groove and the light amount correction surface, and unevenness in the amount of light is less likely to occur.

Patent Document 1: Patent No. 3319945

Disclosure of the invention

Problems to be solved by the invention

However, in the backlight unit of Patent Document 1, the light guide plate (particularly the groove) is a fluorescent tube. Covering. For this reason, when a powerful backlight unit is used in a thin and large-screen liquid crystal television, the size of the light guide plate covering the fluorescent tube becomes extremely large. Therefore, the weight of the knocklight unit is very heavy. In addition, the cost of the backlight unit increases due to the large light guide plate.

[0012] Further, the light amount correction surface is positioned so as to overlap above the interval between the fluorescent tubes at a position overlapping above the fluorescent tubes. For this reason, light traveling directly above the fluorescent tube (light directly above) is not sufficiently scattered, and unevenness in the amount of light cannot be sufficiently suppressed.

[0013] In the light guide plate having a relatively large area that covers the plurality of fluorescent tubes, light travels in various directions (there is much propagating light that also propagates various directional forces in the light guide plate). For this reason, even if the light directly above is scattered by the groove of the light guide plate, light from other directions may be directed toward the upper side of the fluorescent tube. Is difficult to suppress.

In addition, since the groove portion of the light guide plate covers the fluorescent tube, the light reflected by this groove portion may return to the fluorescent tube and be absorbed by the fluorescent tube as it is. Then, the light emission amount of the fluorescent tube is not fully utilized, and the light emission amount is lost.

[0015] The present invention has been made to solve the above problems. And the objective is to provide the backlight unit which can suppress light quantity nonuniformity efficiently, and also to provide a liquid crystal display device provided with this backlight unit. Means for solving the problem

[0016] The present invention includes a single linear light source that emits light, and includes a single optical path changing block that overlaps with the linear light source and refracts incident light to change the optical path. It is a knock light unit. The optical path changing block in the backlight unit having power is provided with an incident surface on which light is incident, and an output surface on which light having the rear force and incident surface force is emitted. In addition, the exit surface has a notch that is recessed.

[0017] In the above backlight unit, it is desirable that the following conditional expression (1) is satisfied.

BWout≤L / 2… Conditional expression (1)

However, BWout: The shortest length from the wall surface of the notch that appears on the exit surface of the optical path changing block to the end of the nearest exit surface along the same direction as the width direction of the linear light source. ,

From the wall surface of the notch that appears on the exit surface of the optical path changing block, along the same direction as the width direction of the linear light source, from the center of the width of the linear light source, perpendicular to the arrangement surface of the linear light source And the shortest length to reach a virtual plane parallel to the extending direction of the linear light source,

Sum of

L: The width of the backlight unit in the direction along the width direction of the linear light source.

[0018] The knock light unit of the present invention includes a plurality of linear light sources that emit light, and overlaps with each linear light source to refract the incident light and change the optical path. A plurality of optical path changing blocks may be included. In the powerful backlight unit, the optical path changing block includes an incident surface on which light is incident and an output surface on which light from the incident surface is emitted from the back surface. In addition, the exit surface has a notch that is recessed.

[0019] In the above backlight unit, it is desirable that the following conditional expression (2) is satisfied.

BWout≤V / 2… Conditional expression (2)

However,

BWout: The shortest length from the wall surface of the notch that appears on the exit surface of the optical path changing block to the end of the nearest exit surface along the same direction as the width direction of the linear light source. ,

Sum of V: Arrangement interval between linear light sources arranged in the plane

It is.

[0020] Regardless of the number of linear light sources and optical path changing blocks, in the knock light unit, the side surface of the optical path changing block having the end of the entrance surface and the end of the exit surface as a part of the outer periphery is It is desirable to have a curved surface that is concave from the outside to the inside, or from the inside to the outside!

In particular, it is desirable that a diffusing plate for diffusing light traveling from the optical path changing block is included, and that the diffusing plate and the incident surface of the optical path changing block be parallel.

[0022] Further, the present invention includes a plurality of linear light sources that emit light, and is arranged so as to overlap corresponding to each linear light source, and refracts incident linear light source light. This backlight unit includes a plurality of optical path changing blocks that change the optical path. The optical path changing block in the knock light unit is positioned closest to the fluorescent tube, so that an incident surface that allows light from the fluorescent tube to enter and an outgoing surface that emits light most distant from the incident surface. It has.

[0023] The incident surface overlaps both ends of the width of the incident surface and both ends of the width of the linear light source in the overlapping direction of the linear light source and the optical path changing block. On the other hand, the exit surface extends in the same direction as the extending direction of the linear light source and has a notch that is V-shaped in the vertical cross section of the extending direction, and in the overlapping direction of the linear light source and the optical path changing block, Superimpose both ends of the width and the ends of the width of the linear light source.

[0024] Further, the following conditional expressions (3) and (4) are satisfied in the knocklight unit.

CA <B 0… Conditional expression (3)

V / 5≤BWout≤V / 2… Conditional expression (4)

However,

CA: Critical angle of optical path change block

B Θ: Inclination angle of the wall surface at the notch (however, the inclination angle that is directed from the inside of the wall surface to the incident surface of the optical path changing block)

V: Arrangement interval between linear light sources arranged in the plane

BWout: Linear light from the notched wall surface that appears on the exit surface of the optical path changing block The shortest length to the end of the nearest exit surface along the same direction as the width direction of the source,

Sum of

It is.

[0025] In such a backlight unit, the optical path changing block overlapping the linear light source includes at least an entrance surface and an exit surface. Then, both ends of the width on the incident surface and both ends of the width of the linear light source overlap in the overlapping direction of the linear light source and the optical path changing block. In such a case, the width and incidence of the linear light from the linear light source {particularly, the light traveling in the vertical direction (directly above) with respect to the arrangement surface of the linear light source arranged in the plane; Since the width of the light source and the width of the surface coincide with each other, it becomes easy for the linear light to enter the incident surface without leakage (if the longitudinal direction of the incident surface and the extending direction of the linear light source match) Linear light is more difficult to leak).

On the other hand, a cut is formed on the exit surface! This notch is formed by extending both ends of the width of the notch itself in the overlapping direction of the linear light source and the optical path changing block just extending in the same direction as the extending direction of the linear light source. Superimpose on both ends. For this reason, the notch is likely to receive linear light traveling through the incident surface.

[0027] However, the cut has a groove that is V-shaped in a vertical section in the extending direction of the linear light source. For this reason, the light that reaches this notch is refracted by the wall surface of the notch (the inner wall of the groove). The factor determining the refraction progress of such light is the incident angle with respect to the wall surface of the cut. Therefore, in the optical path changing block, the inclination angle of the wall surface satisfies the above conditional expression (3).

[0028] When the conditional expression (3) is satisfied, when the linear light (particularly light directly above) is incident on the cut wall surface, the incident angle becomes larger than the critical angle of the optical path changing block. Therefore, enter the wall The light to be reflected is totally reflected. Then, a part of the linear light travels in a direction different from the directly upward direction without passing through the wall surface of the cut and proceeding in the directly upward direction. As a result, the light from the linear light source concentrates in a direct upward direction, and an excessively bright space does not occur. In addition, if light traveling in a direction different from the direction directly above reaches between the linear light sources! /, Generation of space is suppressed excessively.

[0029] It should be noted that a part of the light traveling in a direction different from the direction directly above the light exit surface and side surface of the optical path changing block (a surface in which the end of the entrance surface and the end of the exit surface are part of the outer periphery) However, if the size of the exit surface is too small, the size of the side surface becomes too small, and the amount of light that reaches between the linear light sources through both sides (the exit surface and the side surface) is compared. A small amount. Conversely, if the size of the exit surface is large, adjacent optical path changing blocks will interfere with each other. Therefore, in the knocklight unit, the above conditional expression (4) is established so as to define a balance that does not cause interference between adjacent optical path changing blocks while ensuring the amount of light reaching between the linear light sources. It will be satisfied.

[0030] Therefore, in the backlight unit as described above, the optical path changing block suppresses the generation of both a space that becomes excessively bright due to the concentration of light and a space that becomes excessively dark because the light does not reach. is doing. Therefore, there is no unevenness in the amount of light in the knocklight unit. In other words, the optical path changing block corresponding to each linear light source efficiently prevents unevenness in the light amount of the backlight unit.

In addition, the surface shape of the side surface of the optical path changing block in which the entrance surface, the exit surface, and the end of the entrance surface and the end of the exit surface are part of the outer periphery in the optical path change block is particularly limited. is not. However, there are desirable surface shapes.

For example, the incident surface in the optical path changing block is preferably a plane parallel to the arrangement surface of the linear light source. If this is the case, the light directly above is difficult to be refracted by the incident surface, and proceeds directly as it is, so that it becomes easy to reach the cut at the exit surface of the optical path changing block.

[0033] Further, the exit surface in the optical path changing block is also preferably a plane parallel to the arrangement surface of the linear light source. In this case, the distance between the linear light source and the optical path changing block in the overlapping direction becomes the minimum length, and the thickness of the backlight unit becomes relatively thin. It is.

[0034] Further, it is preferable that the side surface of the optical path changing block has a concave curved surface from the outside to the inside. In this way, when the light that also advances the cutting force reaches the side where the force is applied and passes through, the light travels while diverging. Therefore, if the space between the linear light sources is located at the travel destination of the light, the light reaches the space between them sufficiently.

[0035] However, the side surface of the optical path changing block is not limited to a concave curved surface from the outside to the inside. That is, the side force of the optical path changing block having the end portion of the entrance surface and the end portion of the exit surface as a part of the outer periphery may be a curved surface with a raised surface facing outward.

Incidentally, a sharp portion (for example, corner, edge, corner; edge) is generated on the surface of the optical path changing block. In such an edge, either a bright or dark state can occur excessively depending on the shape of the edge, the incident angle of light, and the like. Therefore, it is desirable that the sharp part to prevent such a situation is curved.

[0037] For example, it is desirable that the bottom portion of the cut, the connection portion between the entrance surface and the side surface, the connection portion between the exit surface and the side surface, and the connection portion between the cut wall surface and the exit surface are curved surfaces. . It should be noted that it is not necessary for all the enumerated parts to have curved surfaces, and at least one part may be curved.

[0038] Further, between the linear light sources arranged in the plane, a triangular prism-shaped optical path changing column having at least two side walls as reflecting surfaces is arranged, and the optical path changing column is one Desirably, with the side walls at the bottom, the two side walls, which are reflective surfaces, facing the linear light source, and the connecting portion between the reflective surfaces is close to the optical path changing block.

[0039] In this way, the optical path changing column has a tapered shape with a tapered top, which may be! When the optical path changing block is positioned on the top side of the striking optical path changing pillar, the side wall (reflecting surface) of the optical path changing pillar is inclined so as to look up toward the optical path changing block. Therefore, when the light from the linear light source and the light that has passed through the optical path changing block are incident on the reflecting surface of the optical path changing column, light (reflected light) that jumps between the linear light sources is generated. For this reason, the light also travels upward between the linear light sources, which are relatively hard to reach light. It will be.

[0040] Further, in the overlapping direction of the linear light source and the optical path changing block, the end of the linear light source closest to the optical path changing block is the first end, and the end of the linear light source facing the first end If the is the second end, it is desirable that the top of the optical path changing column is located corresponding to the distance between the first end and the second end in the overlapping direction.

[0041] For example, if the bottom of the optical path changing column is at a fixed position and the top of the optical path changing column is higher than the first end in the overlapping direction, the reflection surface becomes relatively large, while the optical path changing If the top of the column is lower than the second end in the stacking direction, the reflecting surface becomes a relatively small area. Then, depending on the width of the reflecting surface, a phenomenon in which light is refracted excessively or a phenomenon in which only a small amount of light refracts may occur. Energetic phenomena can contribute to uneven light intensity. Therefore, when the top of the optical path changing column is positioned lower than the first end and higher than the second end in the overlapping direction, the size of the reflecting surface becomes appropriate and causes no unevenness in the amount of light. It will be.

[0042] In addition, when the incident surface of the optical path changing block and the side wall that forms the bottom of the optical path changing column are parallel, the following conditional expression (5) It is desirable to satisfy

Ρ θ = Β Θ… Conditional expression (5)

However,

Θ Θ is the angle of inclination from the inside of the reflecting surface of the optical path changing column toward the inside of the side wall that is the bottom of the optical path changing column.

[0043] In this way, the directional force matches, and the wall surface of the slit and the reflection surface of the optical path changing column become parallel. For this reason, the reflecting surface of the optical path changing column easily receives the light traveling from the wall surface of the notch, and the light is efficiently reflected. As a result, the light reliably travels upward between the linear light sources.

[0044] It is desirable that the light path changing block force includes a diffusing plate that diffuses the traveling light, and that the diffusing plate and the incident surface of the optical path changing block are parallel.

[0045] A liquid crystal display device having the above backlight unit and a liquid crystal display panel that receives light from the powerful backlight unit can also be said to be the present invention. The invention's effect

[0046] According to the present invention, the optical path changing block is arranged corresponding to each linear light source. In addition, this optical path changing block is arranged to easily receive linear light (especially light directly above) from the light source! /, And at the same time, the linear light is easily refracted in directions other than directly above. have. For this reason, unevenness in the light quantity (brightness unevenness, lamp unevenness, lamp image) of the knock light unit due to light directly above is efficiently prevented.

Brief Description of Drawings

[0047] FIG. 1 is a cross-sectional view showing a plurality of optical path changing blocks in the same cross section as FIG.

FIG. 2 is a perspective view of an optical path changing block.

FIG. 3 is a cross-sectional view taken along the line AA ′ in FIG.

FIG. 4 is a perspective view of an optical path changing block showing another example of FIG.

FIG. 5 is a cross-sectional view taken along line BB ′ of FIG.

FIG. 6 is a plan view showing the lamp holder.

[Fig. 7] is an illuminance distribution diagram of the backlight unit equipped with the optical path changing block shown in Fig. 2.

[FIG. 8] is an illuminance distribution diagram of the backlight unit equipped with the optical path changing block shown in FIG.

[FIG. 9] is an illuminance distribution diagram in a backlight unit not equipped with an optical path changing block.

[FIG. 10] is a cross-sectional view of a backlight unit equipped with a single fluorescent tube and an optical path changing block.

FIG. 11A is a cross-sectional view of a backlight unit in which the width of the incident surface and the width of the cut in the optical path changing block are narrower than the width of the fluorescent tube.

FIG. 11B is a cross-sectional view of the backlight unit in which the width of the entrance surface in the optical path changing block is narrower than the width of the fluorescent tube and the width of the notch is wider than the width of the fluorescent tube.

FIG. 11C is a cross-sectional view of the backlight unit in which the width of the incident surface and the width of the cut in the optical path changing block are wider than the width of the fluorescent tube.

[FIG. 11D] is a cross-sectional view of the knock light unit in which the width of the entrance surface in the optical path changing block is wider than the width of the fluorescent tube, and the width of the cut is narrower than the width of the fluorescent tube. FIG. 12A is a cross-sectional view of a backlight unit in which the side surface of the optical path changing block is a flat surface.

[FIG. 12B] is a cross-sectional view of the backlight unit in which the side surface of the optical path changing block is a raised curved surface facing the inner side force.

FIG. 13] is an exploded perspective view of the liquid crystal display device.

FIG. 14 is a three-sided view of a liquid crystal display device.

FIG. 15 is a cross-sectional view of a conventional backlight unit.

Explanation of symbols

BK optical path change block

1 Main body in optical path change block

11 Incident surface of optical path change block

11a Both ends of the incident surface width in the optical path changing block

12 Outgoing surface of optical path change block

13 Side of the optical path change block

CT cut

Both ends of CTa cut width

14 Wall with slit

2 Support in optical path changing block

PE optical path change pillar

SW Optical path change pillar side wall

SW1 Side wall that becomes the bottom of the optical path change pillar

SW2 Side wall that functions as a reflecting surface at the optical path changing column

SW3 Side wall that functions as a reflection surface at the optical path changing column

31 Connection between reflection surfaces in the optical path changing column (top)

J1 notch bottom

J2 Connection between incident surface and side surface in optical path changing block

J3 Connection between the exit surface and side surface in the optical path changing block

J4 Connection between notch and exit surface in optical path changing block 41 Fluorescent tube (Linear light source)

41a End of fluorescent tube (both ends of the width of the linear light source)

41b End of fluorescent tube (first end of linear light source)

41c End of fluorescent tube (second end of linear light source)

D1 Fluorescent tube alignment direction, optical path change block alignment direction, optical path change column alignment direction

D2 Fluorescent tube extending direction, optical path changing block extending direction, optical path changing column extending direction

S Fluorescent tube placement surface

P Stacking direction of fluorescent tube and optical path changing block

V Interval between fluorescent tubes

51 Liquid crystal display

52 knock light unit

59 Liquid crystal display

BEST MODE FOR CARRYING OUT THE INVENTION

[0049] [Embodiment 1]

An embodiment of the present invention will be described below with reference to the drawings. In addition, although a member number and hatching may be abbreviate | omitted for convenience for some drawings, in such a case, other drawings shall be referred to. Also, the black circle on the drawing means the direction perpendicular to the page.

[0050] [1. Liquid crystal display device]

As shown in an exploded perspective view of FIG. 13 and a three-sided view of FIG. 14 comprising a plan view “short cross-sectional view” and a long cross-sectional view, the liquid crystal display 59 includes a liquid crystal display panel 51 and a backlight unit 5 And have. However, both drawings omit a later-described lamp holder 45 for the sake of convenience, and the longitudinal sectional view of FIG. 14 does not illustrate an optical path changing column PE which will be described later for the sake of convenience.

[0051] The liquid crystal display panel 51 is a non-light-emitting display panel, and exhibits a display function by receiving light from the backlight unit 52 (backlight light). Therefore, if the light from the knock light unit 52 can irradiate the entire surface of the liquid crystal display panel 51 uniformly, the liquid crystal display panel The display quality of Nell 51 will be improved.

[0052] The knock light unit 52 includes a fluorescent tube (light source) 41, an optical path changing pillar PE, a reflection frame 42, an optical path changing block BK, a diffusion sheet 43, and an optical sheet 44 to generate knock light. Is included.

[0053] The fluorescent tube (linear light source) 41 is, for example, a cold cathode tube or a hot cathode tube, and has a linear shape (bar shape, cylindrical shape, etc.) as shown in FIGS. Multiple units are arranged in parallel in the crite unit 52 (however, for convenience, only a part of the numbers are shown in the drawing). Therefore, the arrangement direction of the fluorescent tubes 41 can be defined as the first direction Dl, the extending direction (longitudinal direction) of the fluorescent tubes 41 can be defined as the second direction D2, and the arrangement plane of the fluorescent tubes 41 arranged in the plane can be defined as the arrangement plane S. .

The optical path changing column PE is a reflecting member made of white resin having a reflecting function such as polycarbonate, and is disposed between the fluorescent tube 41 and the fluorescent tube 41. Therefore, the arrangement direction of the optical path changing pillars PE is the same as the first direction D1, which is the arrangement direction of the fluorescent tubes 41. In addition, the optical path changing column PE is a triangular column and is a linear member (column member) having the column direction as a longitudinal direction, and the linear extending direction (longitudinal direction) is the extending direction of the fluorescent tube 41. It is in the same direction as the second direction D2. Since the optical path changing column PE is disposed between the fluorescent tube 41 and the fluorescent tube 41, the light reaching the fluorescent tube 41 is reflected to be refracted.

[0055] The reflection frame 42 is a box-shaped member having an open surface, and covers the box-shaped inner surface with a resin or metal having a reflection function. And the fluorescent tube 41 etc. are located in this box-shaped inner surface. Therefore, a part of the radial light emitted from the fluorescent tube 41 (radial light centered on the fluorescent tube 41) is reflected and guided to the open surface. Note that the constituent members of the reflection frame 42 may be made of a resin or metal having a reflection function. This is because the resin or metal that covers the inner surface of the reflection frame 42 can be removed.

[0056] The optical path changing block BK is a block made of transparent resin such as acrylic resin or polycarbonate, and is positioned so as to overlap the fluorescent tube 41 to cover the powerful fluorescent tube 41 (note that The direction in which the optical path changing block BK overlaps the fluorescent tube 41 is defined as the overlapping direction P). For this reason, the arrangement direction of the optical path changing blocks BK is the same as the first direction D1, which is the arrangement direction of the fluorescent tubes 41. The optical path changing block BK extends to cover the length of the fluorescent tube 41. Since it has a shape (linear, bar-like, etc.), the extending direction (longitudinal direction) of the optical path changing block BK is the same as the second direction D2, which is the extending direction of the fluorescent tube 41.

The diffusion sheet 43 is formed of a resin such as PET (Poly Ethylene Terephthalate) having a function of scattering and diffusing light, and is positioned so as to cover the optical path changing block BK. For this reason, when light that has also advanced the optical path changing block BK force is incident on the diffusion sheet 2, the light is scattered and diffused, and spreads in the in-plane direction.

The optical sheet 44 is, for example, a lens sheet that has a lens shape in the sheet surface and deflects (condenses) light radiation characteristics, and is positioned so as to cover the diffusion sheet 43. Therefore, when the light traveling from the diffusion sheet 43 is incident on the optical sheet 44, the light is collected and the light emission luminance per unit area is improved.

[0059] [1 1. About optical path change block]

Here, the optical path changing block BK will be described in detail with reference to FIG. 2 and FIG. 2 is a perspective view of the optical path changing block BK, and FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. 2 (however, for convenience, the fluorescent tube 41 is also shown). The optical path changing block BK has a plate-like main body 1 extending in one direction and supports 2 positioned at both ends of the main body 1 in the extending direction (= second direction D2). In the following, first, the main body 1 will be described mainly.

As shown in FIG. 3, the main body 1 is positioned closest to the fluorescent tube 41 so that light is incident thereon, and an exit surface 12 that is most distant from the incident surface 11 and emits light. And side surfaces 13 (13a ′ 13b) having the end of the incident surface 11 and the end of the output surface 12 as a part of the outer periphery.

The incident surface 11 extends in the same direction as the second direction D2 in which the fluorescent tube 41 extends. In addition, the incident surface 11 is formed by superimposing both ends 1 la '11a of the width of the incident surface 11 and both ends 41a' 41a of the width of the fluorescent tube 41 in the overlapping direction P of the fluorescent tube 41 and the optical path changing block BK. (The width direction of the incident surface 11 and the width direction of the fluorescent tube 41 are the same as the first direction D1). Therefore, the linear light from the fluorescent tube 41, in particular, the width of the light directly above that is the light traveling in the direction perpendicular to the arrangement surface S of the fluorescent tubes 41 arranged in the plane, and the width of the incident surface 11 As a result, the light directly above the light easily enters the incident surface 11 without leaking (the vertical direction with respect to the arrangement surface S is referred to as the direct upward direction). On the other hand, the exit surface 12 extends in the same direction as the second direction D2, which is the extending direction of the fluorescent tube 41, similarly to the entrance surface 11 (note that the width direction of the exit surface 12 is the same as the first direction D1). In the same direction). In addition, the exit surface 12 has a cut CT that extends in the same direction as the second direction D2 and is V-shaped in a vertical section in the extending direction. That is, a groove-shaped cut CT having two wall surfaces 14 (14a, 14b) is formed on the output surface 12.

[0063] In addition, the emission surface 12 has both ends CTa. CTa and both ends 41a and 41a of the width of the fluorescent tube 41 in the overlapping direction P of the fluorescent tube 41 and the optical path changing block BK. Are superimposed. For this reason, the width of the directly overhead light traveling through the incident surface 11 and the width of the cut CT coincide with each other, and the strong direct light easily enters the cut CT without leakage.

[0064] The light incident on the cut CT, that is, the light incident on the wall 14 of the cut CT, is refracted (reflected or transmitted) depending on the incident angle. Then, the travel destination of the light directly on the wall surface 14 is affected by the inclination angle B Θ of the wall surface 14. Therefore, the inclination angle B 0 satisfies the following conditional expression A {conditional expression (3)} (see FIG. 3).

[0065] CA <B 0… Conditional expression A

However,

CA: Optical path change block BK critical angle

B Θ: Inclination angle of wall 14 in notch CT (however, the inclination angle that is directed from the inside of wall 14 to the inside of incident surface 11)

It is.

[0066] The optical path changing block BK has a critical angle CA specific to the material, and light incident at an incident angle exceeding the critical angle CA is totally reflected. Then, if the wall surface 14 satisfies the conditional expression A, for example, as shown in FIG. 3, the incident angle Θ in (angle from the normal NL to the wall surface 14) of the light SB just above the fluorescent tube 41 is The inclination angle B of the wall 14 is the same as B Θ (Θ in = B Θ). Therefore, the directly overhead light SB is totally reflected and proceeds with refraction at a reflection angle 0 out (Θ out = Θ in) which is the same angle as the incident angle Θ in.

That is, if the wall surface 14 is inclined so as to satisfy the conditional expression A, a part of the linear light from the fluorescent tube 41 such as directly above light is totally reflected, and then the light exits on the emission surface 12 or the side surface 13. Proceed with strength. In other words, if conditional expression A is satisfied, a part of the linear light including the direct light will be in the direct upward direction. Go to <<. The critical angle CA of acrylic resin, which is an example of the material of the optical path changing block BK, is 42.15 [°], and the critical angle of polycarbonate is 38.9 [°].

[0068] By the way, a part of the light totally reflected by the wall surface 14 is reflected by the emission surface 12 of the optical path changing block BK, then passes through the side surface 13 and reaches between the fluorescent tubes 41 and 41 ( Of course, there is also light that passes through the side surface 13 without passing through the emission surface 12 and reaches between the fluorescent tubes 41 and 41). For this reason, a phenomenon in which the space between the fluorescent tubes 41 and 41 becomes too dark is prevented. However, if the following conditional expression Β {conditional expression (4)} is not satisfied, a problem will occur (see Fig. 1 in the same section as Fig. 3).

[0069] V / 5≤BWout≤V / 2… Conditional expression B

However,

V: Arranged in-plane! Fluorescent tubes 41 · 41 are arranged at intervals (pitch interval) BWout: Cuts appearing on the exit surface 12 From the CT wall surface 14 in the same direction as the width of the fluorescent tube 41 Along the shortest length BW1 to the end of the nearest exit surface 12,

The center force of the width of the fluorescent tube 41 is perpendicular to the arrangement surface S of the fluorescent tube 41 so that it extends along the same direction as the width direction of the fluorescent tube 41 from the wall surface 14 of the CT that appears on the emission surface 12. And the shortest length BW2 to reach the virtual plane E parallel to the second direction D2, which is the extending direction of the fluorescent tube 41, and

Sum of

It is.

[0070] For example, when the BWout (= BWl + BW2) force conditional expression B is less than the lower limit value, the size (eg, BW1) of the exit surface 12 in each optical path changing block BK becomes too small. Therefore, the distance between the end of the exit surface 12 that is also the outer periphery of the side surface 13 and the end of the entrance surface 11 is shortened, and the size of the side surface 13 is too small. For this reason, there arises a problem that the amount of light reaching between the fluorescent tubes 41 and 41 is reduced via at least one of both surfaces (the emission surface 12 and the side surface 13). On the other hand, when BWout exceeds the upper limit value of conditional expression B, the size of the exit surface 12 becomes too large, and the optical path changing block BK increases in size. Therefore, adjacent optical path change blocks B

不具合 · ΒΚ interferes with the problem.

[0072] Therefore, if BWout is set so that it falls within the range of conditional expression Β,

While the amount of light reaching between 41 and 41 is secured, interference between the light path changing blocks is prevented.

[0073] As described above, the knock light unit 52 includes a plurality of fluorescent tubes 41 that emit light, and is arranged so as to overlap with the fluorescent tubes 41 to receive incident light. It contains multiple optical path changing blocks させる that change the optical path by refracting. In the backlight unit 52, the optical path changing block has an incident surface 11, an output surface 12, and side surfaces 13 (13a-13b).

[0074] Then, in the overlapping direction P of the fluorescent tube 41 and the optical path changing block BK, the incident surface 11 overlaps both ends 1 la '11a of the width of the incident surface 11 and both ends 41a' 41a of the width of the fluorescent tube 41. In addition, the emission surface 12 extends in the same direction as the extending direction of the fluorescent tube 41 (second direction D2), and has a cut CT that is V-shaped in the vertical cross section of the extending direction, and also has an optical path change pro In the overlapping direction P with the CK, the both ends CTa'CTa of the width of the cut CT and the both ends 41a'41a of the fluorescent tube 41 are overlapped.

[0075] In this way, the width of the linear light including the light directly above the fluorescent tube 41 and the width of the incident surface 11 match, so that the linear light is incident without leaking. In addition to being incident on the surface 11, the linear light passing through the incident surface 11 can easily reach the slit CT extending in the same direction as the fluorescent tube 41. For this reason, the linear light refracts in various directions due to the wall surface 14 of the cut CT, making it difficult to concentrate.

[0076] In particular, when the above conditional expression A is satisfied, a part of the linear light (especially light directly above) is totally reflected, so that it is surely concentrated by directing the force directly upward. Therefore, an excessively bright space due to the concentration of light does not occur. Moreover, if the light traveling in a direction different from the direction directly above reaches between the fluorescent tubes 41 and 41, an excessively dark space does not occur.

[0077] When the above conditional expression Β is satisfied, the size of the optical path changing block 、, particularly the output The emission surface 12 and the side surface 13 are appropriately sized, and light traveling through at least one of the emission surface 12 and the side surface 13 reliably reaches between the fluorescent tubes 41 and 41. Therefore, the power space cannot be an excessively dark space. Therefore, in the knock light unit 52, the light amount unevenness of the knock light unit 52 due to an excessively bright space and an excessively dark space occurs. Uneven light intensity in the knock light 52 may be less likely to occur).

In addition, in the backlight unit 52 that is powerful, the optical path changing block BK covers each of the fluorescent tubes 41. That is, the optical path changing block BK does not cover a plurality of fluorescent tubes 41 together like a light guide plate or the like. Therefore, the light mainly entering the optical path changing block BK becomes light from the corresponding fluorescent tube 41, and thus is not easily affected by other fluorescent tubes 41 (adjacent fluorescent tubes 41, etc.).

As a result, unlike the light guide plate or the like, the optical path changing block BK can efficiently guide the light from the fluorescent tube 41 in a desired direction without considering the influence of various lights. That is, the knock light unit 52 equipped with the optical path changing block BK efficiently prevents unevenness in the amount of light. In addition, since the knock light unit 52 does not include a light guide plate, an increase in weight, an increase in cost, and a loss of light amount due to the light guide plate can be prevented.

Note that the surface shapes of the incident surface 11, the exit surface 12, and the side surface 13 of the optical path changing block BK that have been described are not particularly limited. However, there are desirable surface shapes. For example, the surface shape of the incident surface 11 may be a flat surface. This is because, if the incident surface 11 is a plane parallel to the arrangement surface S of the fluorescent tube 41, the light directly above is not bent by the incident surface 11 and proceeds in the upward direction as it is, so that the output surface 12 This is because the notch in CT reaches CT.

[0081] Further, the surface shape of the emission surface 12 in the optical path changing block BK may be a flat surface.

This is because if the emission surface 12 is a plane parallel to the arrangement surface S of the fluorescent tube 41, the distance between the fluorescent tube 41 and the optical path changing block BK in the overlapping direction P becomes the minimum length. This is because the thickness of the light light unit 52 is relatively thin.

However, it is desirable that the surface shape of the side surface 13 in the optical path changing block BK is a concave curved surface (curved surface) from the outside to the inside. Because the side 13 This is because when the light traveling through the slit CT is transmitted, the light diverges. And if the light which diverges in this way arrives between fluorescent tubes 41 * 41, the space between them does not become a space with insufficient light quantity. In particular, the divergent light power between the different side surfaces of the adjacent optical path changing blocks ΒΚ'ΒΚ 13 13 13 is insufficient, and the amount of light between the fluorescent tubes 41 41 41 is insufficient. It will be a space! /

[0083] As shown in Figs. 4 and 5 (Β-Β in Fig. 4, cross-sectional view taken along line arrow), incident surface 11 and side surface 13 (13a, 13a, 13b) Connection part J2'J2, Output surface 12 and side surface 13 (13a '13b) connection part J3' J3, Notch CT wall 14 (14a '14b) and output surface 12 connection part J4' J4 may be a curved surface (that is, the various portions may be 1 to 4 in shape).

[0084] It is assumed that various portions J1 to J4 that are powerful are located on the surface of the optical path changing block BK and are sharply shaped (for example, corners, edges, corners; edges). In such an edge, either a bright or dark state can be excessively generated depending on the shape of the edge, the incident angle of light to the strong edge, and the like. However, if these parts are curved, an excessive light / dark state at such an edge will occur.

[0085] Note that it is not necessary that all of these portions J1 to J4 are curved surfaces, as long as at least one portion is curved. This is because if excessive light and dark conditions at the edge are suppressed even at only one power point, the light quantity unevenness of the knock light unit 52 can be suppressed.

[0086] Next, the support 2 will be described. As shown in FIGS. 2 and 4, the supports 2 · 2 are provided at both ends of the optical path changing block BK in the longitudinal direction of the main body 1 (in the drawings, for convenience, one of the supports 2 Only shown). The support bodies 2 and 2 protrude in a direction perpendicular to the longitudinal direction of the optical path changing block BK, and are provided with a curved notch 21 along the outer periphery of the fluorescent tube 41 at the protruding end (protruding end). Therefore, when the curved cutouts 21 and 21 come into close contact with both ends of the fluorescent tube 41, the optical path changing block ΒΚ is positioned so as to be separated from the fluorescent tube 41 by the protruding amount of the support member 2.2.

Then, as shown in the plan view of FIG. 6 (for the sake of convenience, the optical path changing column 変更 is omitted and the optical path changing block ΒΚ and the fluorescent tube 41 are mainly shown), the optical path changing block ΒΚ is the support 2 · 2 The lamp holder 45 presses against the fluorescent tube 41 through which the fluorescent tube 41 is covered. As a result, the optical path changing block BK and the fluorescent tube 41 are fixed in the reflection frame 42.

[0088] [1-2. Optical path change pillar]

Next, I will explain in detail about the optical path change pillar PE. The optical path changing column PE has a triangular column shape and a linear shape with the column direction as the longitudinal direction. As shown in FIG. 1, the optical path changing pillar PE located between the fluorescent tubes 41 and 41 has one side wall SW1 of the three side walls SW (SW1 to SW3) as the bottom and the remaining side walls SW1 to SW3. The two side walls SW2 and SW3 are facing the fluorescent tubes 41 and 41. Therefore, the sidewall SW2 ′ SW3 functions as a reflecting surface (also referred to as a reflecting surface SW2 ′ SW3). Furthermore, the optical path changing column PE is brought close to the optical path changing block BK with the connecting portion 31 of the reflecting surfaces SW2 'and SW3 as the apex!

[0089] If this is the case, it can be said that the optical path changing column PE is tapered with the apex 31 tapered. Therefore, the reflecting surface SW2-S W3 of the optical path changing column PE which is the tapered side wall SW is inclined so as to face the optical path changing block BK. Then, when the light from the fluorescent tube 41 and the light that has passed through the optical path changing block BK enter the reflecting surface SW2 'SW3, it is reflected so as to jump up to the optical path changing block BK (the reflected light jumps up the light). Also called). As a result, the light also travels upward between the fluorescent tubes 41 and 41, where the light is relatively difficult to reach, and the light quantity unevenness of the knock light unit 52 is surely prevented.

[0090] In the overlapping direction Ρ of the fluorescent tube 41 and the optical path changing block ΒΚ, the end of the fluorescent tube 41 closest to the optical path changing block を is the first end 41b, and the fluorescence facing the first end 41b. When the end portion of the tube 41 is the second end portion 41c, the apex 31 of the optical path changing column PE is positioned in the overlapping direction P corresponding to the distance between the first end portion 41b and the second end portion 41c. That is, the apex 31 is positioned lower than the first end 41b and higher than the second end 41c in the overlapping direction P.

[0091] For example, if the bottom of the optical path changing column PE is at a fixed position and the top 31 of the optical path changing column PE is higher than the first end 41b in the overlapping direction P, the size of the optical path changing column PE is The size becomes relatively large, and the reflecting surface SW2 'SW3 also becomes relatively large. Then, the light is excessively refracted due to the large reflective surface SW2 'SW3, which may cause a non-uniform light amount. [0092] On the other hand, for example, when the bottom of the optical path changing column PE is at a fixed position and the top 31 of the optical path changing column PE is lower than the second end 41c in the overlapping direction P, the optical path changing column PE The size is relatively small, and the reflecting surface SW2 'SW3 is also relatively small in association with it. Then, due to the reflective area SW2 'SW3 having a small area, only a small amount of light is refracted, which may cause unevenness in the amount of light.

[0093] Therefore, if the top 31 of the optical path changing pillar PE is positioned lower than the first end 41b and higher than the second end 41c in the overlapping direction P, the cause of unevenness in the amount of light occurs. become.

[0094] If the incident surface 11 of the optical path changing block BK and the side wall SW1 that is the bottom of the optical path changing pillar PE are parallel, the inclination angle of the reflecting surface SW2 'SW3 of the optical path changing pillar PE is P Θ The following conditional expression C {conditional expression (5)} should be satisfied.

Ρ θ = Β Θ… Conditional expression C

However,

Ρ Θ is the angle of inclination toward the inside of the side surface SW1, which is the bottom of the optical path changing column Ρ E, on the reflecting surface SW2 'SW3 of the optical path changing column ΡΕ.

[0095] In this way, as shown in Fig. 1, the notch CT walls 14 &'141) facing each other and the reflecting surface 3 ¹ ^ 3' 3 ¹ ^ 2 of the optical path changing pillar 1¾ are formed as shown in FIG. Become parallel. More specifically, in the two optical path changing blocks BK'BK that sandwich one optical path changing pillar PE, the wall 14a of one optical path changing block BK and the reflecting surface SW3 are parallel, and the other optical path is changed. The wall 14b of the block BK and the reflecting surface SW2 are parallel. Therefore, the reflecting surfaces SW2 and SW3 of the optical path changing pillar PE are easy to receive the light traveling from the wall surfaces 14b'14a, and the light jumps efficiently. As a result, the light reliably travels upward between the fluorescent tubes 41 and 41.

[0096] [1-3. Comparison of illuminance distribution maps]

Here, the illuminance distribution diagrams of the backlight units 52 and 52 with the optical path changing block の in Figs. 2 and 4 and Figs. 7 and 8 and the illuminance distribution diagrams of the backlight units not equipped with these optical path changing blocks. Compare this with Figure 9.

[0097] In the illuminance distribution diagram, the horizontal axis is the first direction D1 in which the fluorescent tubes 41 are arranged, and the vertical axis is the illuminance [1 x]. The position Z on the illuminance distribution diagram indicates the position [mm] of the fluorescent tube 41 in the first direction D1. Therefore, the illuminance at position Z on the horizontal axis corresponds to the light directly above, and the illuminance on the horizontal axis excluding position Z corresponds to the interval V (arrangement interval V) between the fluorescent tubes 41 and 41. .

[0098] As shown in FIGS. 7 and 8, in the backlight units 52 and 52 including the optical path changing block ΒΚ, the illuminance corresponding to the light directly above is approximately 7000 [lx], and the fluorescent tubes 41 · The illuminance corresponding to the interval V of 41 is about 7000 [lx]. Therefore, the difference between the illuminance corresponding to the light directly above and the illuminance corresponding to the distance V between the fluorescent tubes 41 and 41 is extremely small.

On the other hand, as shown in FIG. 9, in the backlight unit not equipped with the optical path changing block, the illuminance corresponding to the light directly above is about 8500 [lx], while the fluorescent tubes 41. The illuminance corresponding to the interval V of 41 is also about 6500 [lx]. Therefore, the difference between the illuminance corresponding to the light directly above and the illuminance corresponding to the distance V between the fluorescent tubes 41 and 41 is about 1500 [lx].

[0100] Then, as is clear from the comparison between Fig. 9 and Fig. 7 and Fig. 8, in the backlight unit without the optical path changing block, the illuminance corresponding to the light directly above and the distance between the fluorescent tubes 41 · 41 The difference between the illuminance corresponding to V, i.e., the unevenness of the light intensity appears remarkably. On the other hand, in the knocklight units 52 and 52 equipped with the optical path change block Β 照度The difference between the illuminance and the illuminance corresponding to is difficult to occur (that is, the illuminance is uniform), and unevenness in the amount of light is prevented. Therefore, it is clear that the knock light unit 52 of the present invention suppresses unevenness in the amount of light.

[0101] [Other embodiments]

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above description, the backlight unit 52 having a plurality of fluorescent tubes 41 is taken as an example, but the present invention is not limited to this. That is, as shown in FIG. 10, a single fluorescent tube 41 that emits light is included, and an optical path change block させる that overlaps with the fluorescent tube 41 to refract the incident light and change the optical path is provided. Backlight unit including one 52 It may be.

[0103] Further, the shape of the cut CT is not limited to a V-shape in a cross section perpendicular to the second direction D2. For example, as shown in FIG. 10, the wall surface 14 (14a '14b) of the cut CT may be a curved surface. In short, the cut CT should have a shape that is recessed from the exit surface 12.

[0104] The backlight unit 52 including the single fluorescent tube 41 and the optical path changing block BK satisfies the following conditional expression (D) {Conditional expression (1)} in order to suppress the uneven light amount. And desirable.

BWout≤L / 2… Conditional expression (D)

However,

BWout: notch appearing on the exit surface 12 The shortest length BW1 from the CT wall surface 14 to the end of the nearest exit surface 12 along the width direction of the fluorescent tube 41 ,

Sum of

L: The width of the backlight unit 52 in the direction along the width direction of the fluorescent tube 41.

[0105] Further, the optical path changer includes a plurality of fluorescent tubes 41 and has a cut CT having a curved wall 14 (14a '14b) or a V-shaped cut CT having a flat wall 14 (14a' 14b). In the backlight unit 52 including a plurality of further blocks BK, the light quantity unevenness of the knock light unit 52 may not easily occur even if the following conditional expression E {conditional expression (2)} is satisfied.

[0106] BWout≤V / 2… Conditional expression E

However,

V: Arrangement interval between linear light sources arranged in the plane

Sum of

It is.

Further, as shown in FIGS. 11A to 11D, in the overlapping direction P, both ends l la ′ l la of the width of the incident surface 11 and both ends 41a′41a of the width of the fluorescent tube 41 do not overlap each other. Good. Further, in the overlapping direction P, both ends CTa · CTa of the width of the cut CT on the emission surface 12 and both ends 41a′41a of the fluorescent tube 41 need not overlap.

That is, the width of the incident surface 11 may be wider or narrower than the width of the fluorescent tube 41. Further, the width of the cut CT may be wider or narrower than the width of the fluorescent tube 41.

[0109] The degree of the curved surface of the side surface 13 of the optical path changing block BK is not particularly limited. However, the side surface 13 diverges light from the inside and travels to the outside. For example, the center of curvature of the curved surface that is the side surface 13 may be outside the side surface 13 instead of inside.

[0110] Further, the degree of curved surfaces of the portions J1 to J4 in the optical path changing block BK is not limited. The point is that the curved surface can prevent an excessively bright state or an excessively dark state in the portions J1 to J4.

However, as shown in FIG. 3, the surface shape of the side surface 13 is not limited to a concave curved surface facing from the outside to the inside. That is, as shown in FIG. 12A, the side surface 13 may be a flat surface, or as shown in FIG. 12B, the side surface 13 may be a raised curved surface with the inner force facing outward.

[0112] In addition, the optical path changing block BK can be expressed in various ways. For example, the main body 1 of the optical path changing block BK has a rod-like shape, and the outer periphery has an incident surface 11 that is a plane, an exit surface 12 that has a cut CT, and has a larger area than the incident surface, and a side surface 13 that is a curved surface (13a , 13b) Is arranged. Therefore, the cross section perpendicular to the extending direction of the main body 1 can be said to be a trapezoid consisting of the incident surface 11, the output surface 12, and the side surfaces 13a '13b, and the main body 1 can also be referred to as a trapezoidal column (however, a part of the outer periphery of the column A trapezoidal column with a curved surface (a modified trapezoidal column)}.

[0113] Then, assuming that the incident surface 11 of the light path changing block BK, which is a trapezoidal column, is the top surface and the output surface 12 is the bottom surface, the knock light unit 52 changes the optical path of the trapezoidal column with the top surface facing the fluorescent tube 41. More block BK is installed!

[0114] Finally, an embodiment obtained by appropriately combining the techniques disclosed above is naturally included in the technical scope of the present invention! /.

Claims

The scope of the claims

[1] Including a single linear light source that emits light,

It includes a single optical path changing block that overlaps with the linear light source and refracts the incident light to change the optical path.

The optical path changing block includes an incident surface on which the light is incident and an exit surface on which the light having the incident surface force is emitted from the back surface.

The exit surface has a notch that has a hollow shape.

[2] The backlight unit according to claim 1, wherein the following conditional expression (1) is satisfied.

BWout≤L / 2… Conditional expression (1)

However,

BWout: The shortest length from the wall surface of the notch exposed on the exit surface to the end of the exit surface, along the same direction as the width direction of the linear light source,

The central force of the width of the linear light source is perpendicular to the arrangement surface of the linear light source so as to extend along the same direction as the width direction of the linear light source from the wall surface of the notch exposed on the exit surface. And the shortest length to reach a virtual plane parallel to the extending direction of the linear light source,

Sum of

[3] Including a plurality of linear light sources that emit light,

Overlapping corresponding to each linear light source, includes a plurality of optical path changing blocks that refract the incident light and change the optical path,

The exit surface has a notch that has a hollow shape.

[4] The backlight unit according to claim 3, wherein the following conditional expression (2) is satisfied.

BWout≤V / 2… Conditional expression (2) However,

Sum of

V: Arrangement interval between linear light sources arranged in the plane

It is.

[5] Side force of the optical path changing block having the end portion of the entrance surface and the end portion of the exit surface as a part of the outer periphery, or a concave curved surface directed from the outside to the inside, or from the inside to the outside The backlight unit according to claim 1, wherein the backlight unit has a curved surface that is raised.

6. The backlight according to claim 1, further comprising a diffusing plate for diffusing light traveling from the optical path changing block, wherein the diffusing plate and an incident surface of the optical path changing block are parallel to each other. unit.

[7] The side force of the optical path changing block having the end of the entrance surface and the end of the exit surface as a part of the outer periphery is a curved surface that is concave from the outside to the inside, or from the inside to the outside. 4. The backlight unit according to claim 3, wherein the backlight unit has a curved surface that is raised.

8. The backlight according to claim 3, further comprising a diffuser that diffuses light traveling from the optical path changing block, wherein the diffuser and the incident surface of the optical path changing block are parallel to each other. unit.

[9] including a plurality of linear light sources emitting light,

The optical path changing block includes an incident surface on which the light is incident by being located closest to the linear light source, and an output surface on which the incident surface force is most dissociated to emit the light. And

The incident surface overlaps both ends of the width of the incident surface and both ends of the width of the linear light source in the overlapping direction of the linear light source and the optical path changing block,

The exit surface extends in the same direction as the extending direction of the linear light source and has a notch that is V-shaped in a vertical section in the extending direction. In the overlapping direction of the linear light source and the optical path changing block, The both ends of the width of the notch are overlapped with both ends of the width of the linear light source, and the backlight unit satisfying the following conditional expressions (3) and (4); CA <B 0 ... Conditional expression (3)

V / 5≤BWout≤V / 2… Conditional expression (4)

However,

CA: Critical angle of optical path change block

B Θ: Inclination angle of the wall surface at the above-mentioned notch (however, the inclination angle that is directed from the inside of the wall surface to the inside of the incident surface)

V: Arrangement interval between linear light sources arranged in the plane

Sum of

It is.

10. The backlight unit according to claim 9, wherein the incident surface in the optical path changing block is a plane parallel to the arrangement surface of the linear light source.

11. The backlight unit according to claim 9, wherein the exit surface in the optical path changing block is a plane parallel to the arrangement surface of the linear light source.

[12] An optical path changing block in which the end of the entrance surface and the end of the exit surface are part of the outer periphery. 10. The knock light unit according to claim 9, wherein a side surface of the lock becomes a concave curved surface from the outside to the inside! /.

[13] The side of the optical path changing block having the end of the entrance surface and the end of the exit surface as a part of the outer periphery is a raised curved surface whose inner force is also directed outward. Backlight unit.

[14] The bottom portion of the cut, a connection portion between the incident surface and the side surface, a connection portion between the emission surface and the side surface, and a connection portion between the wall surface of the cut and the emission surface.

10. The backlight unit according to claim 9, wherein at least one of the surfaces is a curved surface! /.

[15] Between the linear light sources arranged in the plane, a triangular prism-shaped optical path changing column having at least two side walls as reflecting surfaces is arranged.

The optical path changing column has one side wall at the bottom, the two side walls, which are reflective surfaces, are directed to the linear light source, and the connecting portion between the reflecting surfaces is the top to approach the optical path changing block. The knocklight unit according to claim 9.

[16] In the overlapping direction of the linear light source and the optical path changing block, the end of the linear light source closest to the optical path changing block is the first end, and the end of the linear light source facing this first end is Is the second end,

16. The backlight unit according to claim 15, wherein the top of the optical path changing column is located corresponding to a distance between the first end and the second end in the overlapping direction.

[17] When the incident surface of the optical path changing block is parallel to the side wall that is the bottom of the optical path changing column,

The backlight unit according to claim 16, which satisfies the following conditional expression (5): P Θ force which is an inclination angle of the reflecting surface of the optical path changing column;

Ρ Θ = Β Θ ■■■ Conditional expression (5)

However,

18. A diffusing plate that diffuses light traveling from the optical path changing block is included, and the diffusion plate and the incident surface of the optical path changing block are parallel to each other. Light unit.

A liquid crystal display device comprising: the backlight unit according to any one of claims 1 to 18; and a liquid crystal display panel that receives light from the backlight unit.