WO2013018499A1 - Rétro-éclairage et dispositif d'affichage à cristaux liquides - Google Patents

Rétro-éclairage et dispositif d'affichage à cristaux liquides Download PDF

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Publication number
WO2013018499A1
WO2013018499A1 PCT/JP2012/067216 JP2012067216W WO2013018499A1 WO 2013018499 A1 WO2013018499 A1 WO 2013018499A1 JP 2012067216 W JP2012067216 W JP 2012067216W WO 2013018499 A1 WO2013018499 A1 WO 2013018499A1
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WO
WIPO (PCT)
Prior art keywords
light
guide plate
led
light guide
backlight
Prior art date
Application number
PCT/JP2012/067216
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English (en)
Japanese (ja)
Inventor
増田　純一
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シャープ株式会社
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Filing date
Publication date
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Publication of WO2013018499A1 publication Critical patent/WO2013018499A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0081—Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging
    • G02B6/0086—Positioning aspects
    • G02B6/0091—Positioning aspects of the light source relative to the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0081—Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging
    • G02B6/0085—Means for removing heat created by the light source from the package
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/133308—Support structures for LCD panels, e.g. frames or bezels
    • G02F1/133317—Intermediate frames, e.g. between backlight housing and front frame

Definitions

  • the present invention relates to an edge light type backlight using an LED as a light source and a liquid crystal display device using the backlight.
  • the liquid crystal display device includes a liquid crystal panel unit and a backlight disposed on the back surface of the liquid crystal panel unit, and the liquid crystal panel unit adjusts a light transmittance (amount of transmission) from the backlight, An image is displayed on the front surface of the liquid crystal panel unit.
  • the backlight there is a light guide plate method (edge light method) in which light is incident from the side surface of the light guide plate. Since the edge light type backlight has a structure in which light is incident from the side surface of the light guide plate, it is difficult to emit large planar light with a uniform luminance distribution. Therefore, an edge light type backlight is often used for a small liquid crystal display device such as a notebook PC monitor or a gaming machine monitor.
  • the edge-light type backlight has a light source unit in which a plurality of LEDs are arranged side by side, receives light emitted from the light source unit from a light receiving surface on a side surface, and receives planar light from a light emitting surface of one main surface.
  • An output light guide plate, an optical sheet disposed adjacent to the light exit surface of the light guide plate, and a reflection sheet disposed adjacent to a surface opposite to the light exit surface of the light guide plate are provided. These members are arranged inside the backlight chassis.
  • the light guide plate is used to efficiently cause the light emitted from the LED to enter the light guide plate, that is, to prevent the light emitted from the LED from coming off the light receiving surface. Is arranged so that the light receiving surface is close to the LED.
  • a semiconductor light emitting element such as an LED has a characteristic that the temperature rises when the input current increases. If the light receiving surface and the LED are too close together, it is difficult to release the heat of the LED, the temperature rises, and the light emission efficiency decreases. Due to the decrease in the light emission efficiency of the LED, uneven brightness of the planar light emitted from the backlight, a decrease in brightness, and the like have occurred, causing a decrease in the quality of the backlight.
  • FIG. 11 is a cross-sectional view of a conventional backlight with a countermeasure against heat.
  • the backlight 91 includes a light guide plate 92, a light source 95 including a film substrate 93 on which LEDs 931 are mounted in a row and a metal reflector 94, and a light source 95 attached to the light guide plate 92.
  • a frame-like frame 96 and a planar frame 97 for storing and holding are provided.
  • An optical sheet 98 made of a plurality of optical members is provided on the light exit surface of the light guide plate 92.
  • a metal thin film 932 and a soft aluminum sheet 933 are attached to the surface of the film substrate 93 where the LED 931 is not mounted.
  • the metal thin film 932 and the soft aluminum sheet 933 are held by the frame-shaped frame 96, and the frame-shaped frame 96 and the metal reflector 94 are attached by a heat-dissipating film sheet 90 (see Japanese Patent Application Laid-Open No. 2003-76287). .
  • the heat generated from the LED 931 is released to the frame-shaped frame 96 through the metal thin film 932 and the soft aluminum sheet 933 disposed in contact with the film substrate 93, so that the light guide plate 92 is heated by the heat generated from the LED 931 or the LED 931 itself. It is possible to suppress the temperature from rising. Thereby, the deterioration of the quality of the backlight by the heat
  • the heat generated from the LED 931 is transmitted to the film substrate 93 and is transmitted through the metal thin film 932 and the soft aluminum sheet 933 to the frame frame 96, the heat dissipation film sheet 90, and the planar shape.
  • heat is radiated to the frame 97, an air layer is easily formed between components (for example, the metal thin film 932 and the frame-shaped frame 96), which may cause a decrease in heat dissipation.
  • the light guide plate 92 is fixed by a plurality of members (planar frame 97, frame frame 96, etc.) and the light source 95 and the light guide plate 92 are disposed close to each other, the light guide plate 92 is likely to warp due to thermal expansion. When the light guide plate 92 is warped, the optical axes of the light receiving surface of the light guide plate 92 and the light emitting surface of the LED 931 are shifted, and light leakage is likely to occur. In addition, since the light source 95 and the light guide plate 92 are in contact with each other, when the light guide plate 92 expands due to the heat of the LED 931, the LED 931 may be pushed to destroy the LED 931.
  • the number of constituent members such as the metal thin film 932, the soft aluminum sheet 933, the heat dissipation film sheet 90, and the like increases, so that the time and labor required for the production increase, and the production cost tends to increase.
  • the present invention suppresses light leakage from the LED and reduction of the light emission efficiency of the LED without increasing the number of components, and provides an edge light type backlight having high light utilization efficiency and a liquid crystal display device using the backlight.
  • the purpose is to provide.
  • the present invention provides a light guide plate that receives light from a light receiving surface on a side surface and emits planar light from a light exit surface of one main surface, and an LED mounting in which a plurality of LEDs are mounted in a row. And an LED substrate having a U-shaped cross section including a first facing portion and a second facing portion that protrude from the LED mounting portion and surround the LED, and the LED substrate is mounted on the LED mounting surface.
  • a backlight attached to the light guide plate such that the portion faces the light receiving surface, the first facing portion contacts the light exit surface, and the second facing portion contacts the back surface of the light exit surface.
  • the LED substrate can efficiently dissipate heat, it is not necessary to provide a heat dissipating member, and accordingly, the increase in the number of members can be suppressed, which is advantageous for downsizing and weight reduction.
  • the LED substrate may be formed of a metal material.
  • the thermal conductivity of the LED substrate is high, an increase in temperature of the LED and the light guide plate can be suppressed. From this, the fall of the luminous efficiency of the said LED can be suppressed, and generation
  • the metal material constituting the LED substrate include aluminum and copper having high thermal conductivity. In addition to these, metals having high thermal conductivity can be employed.
  • the LED substrate may be manufactured by bending a flat metal substrate on which a notch is formed.
  • the LED substrate can be easily manufactured and processing accuracy can be increased, and a gap between the first facing portion and the light guide plate and between the second facing portion and the light guide plate is hardly generated. From this, it can suppress efficiently that the light emitted from the said LED leaks. Moreover, since the 1st opposing part and the 2nd opposing part can move to the direction which opens mutually, it is easy to attach to a light-guide plate.
  • a white resist may be applied to a surface of the LED mounting portion, the first facing portion, and the second facing portion that faces the light guide plate.
  • the white resist preferably has a reflectance of 70% or more, more preferably 80% or more. A higher reflectance is preferable because more light can be reflected and the light utilization rate can be increased.
  • the white resist include a photoresist formed by a photolithography method, a screen printing resist, or the like.
  • At least surfaces of the first facing portion and the second facing portion that are in contact with the light guide plate may be roughened.
  • At least one of the first facing portion and the second facing portion facing the light guide plate may be formed such that a gap is opened between the end portion side and the light guide plate.
  • the first counter portion or the A column portion for maintaining a gap between the second facing portion and the light guide plate may be formed.
  • the column portion may be a columnar one that makes point contact with the light guide plate or a plate-like one that makes line contact with the light guide plate.
  • a liquid crystal display apparatus in which a liquid crystal panel unit is disposed on the front side of the backlight can be cited.
  • the present invention since the first facing portion and the second facing portion are in contact with the light guide plate, leakage of light emitted from the LED can be suppressed. Moreover, since the heat generated from the LED can be efficiently dissipated, it is possible to suppress light leakage due to deformation of the light guide plate and a decrease in light emission efficiency due to the LED itself becoming a high temperature. Can be suppressed.
  • FIG. 1 is an exploded perspective view of an example of a liquid crystal display device including a backlight according to the present invention.
  • FIG. It is sectional drawing of the liquid crystal display device shown in FIG. It is a front view of the light source unit used for the backlight concerning this invention. It is sectional drawing of the light source unit shown in FIG. It is a front view which shows arrangement
  • FIG. 1 is an exploded perspective view of an example of a liquid crystal display device having a backlight according to the present invention
  • FIG. 2 is a cross-sectional view of the liquid crystal display device shown in FIG.
  • the liquid crystal display device A includes a backlight 1 and a liquid crystal panel unit 6.
  • the liquid crystal panel unit 6 is disposed on the front side (observer side) of the backlight 1, and the liquid crystal panel unit 6 is held by a metal bezel 7 having an opening window 70 in the center. It has been.
  • the upper side of the drawing is the front side, that is, the observer side, and the lower side is the back side. Further, in the following description, the description will be given with reference to the front surface and the back surface in the state of FIG. 1 or 2 unless otherwise specified.
  • the backlight 1 is an illumination device that irradiates the liquid crystal panel unit 6 with planar light.
  • the backlight 1 includes a flat light guide plate 2, a light source unit 3 that emits light toward a light receiving surface 22 formed on a side surface of the light guide plate 2, and an optical sheet 4 that is disposed in the vicinity of the light guide plate 2.
  • the backlight 1 includes a backlight chassis 10, and at least the light guide plate 2, the light source unit 3, and the optical sheet 4 are disposed inside the backlight chassis 10.
  • the detail of the backlight 1 which is the principal part of this invention is mentioned later.
  • the liquid crystal panel unit 6 includes a liquid crystal panel 61 in which liquid crystal is sealed, and a polarizing plate 62 attached to the front surface (observer side) and the back surface (backlight 1 side) of the liquid crystal panel 61.
  • the liquid crystal panel 61 includes an array substrate 611, a counter substrate 612 disposed to face the array substrate 611, and liquid crystal filled between the array substrate and the counter substrate.
  • the array substrate 611 is provided with a source wiring and a gate wiring orthogonal to each other, a switching element (for example, a thin film transistor) connected to the source wiring and the gate wiring, a pixel electrode connected to the switching element, an alignment film, and the like.
  • the counter substrate 612 is provided with a color filter in which colored portions of red, green, and blue (RGB) are arranged in a predetermined arrangement, a common electrode, an alignment film, and the like.
  • the array substrate 611 is formed so as to protrude from the counter substrate 612.
  • a circuit for driving the switching element is formed in the protruding portion, and the drive substrate 8 is connected via the flexible substrate 81.
  • the drive substrate 8 transmits a drive signal to the switching elements of the array substrate 611 via the flexible substrate 81.
  • a voltage is applied between the array substrate 611 and the counter substrate 612 in each pixel of the liquid crystal panel 61.
  • the light transmission degree in each pixel is changed. As a result, an image is displayed in the image display area on the viewer side of the liquid crystal panel 61.
  • the bezel 7 is a metal frame, and has a shape that covers the front edge of the liquid crystal panel unit 6.
  • the bezel 7 includes a rectangular opening window 70 formed so as not to hide the image display area of the liquid crystal panel unit 6, a presser 71 that presses the liquid crystal panel unit 6 from the front side, and a rear side from the edge of the presser 71.
  • the cover part 72 which protrudes to the side and covers the edge part of the liquid crystal panel unit 6 and the backlight 1 is provided.
  • the bezel 7 is grounded and shields the liquid crystal panel unit 6 and the backlight 1.
  • the drive substrate 8 is attached to a chassis case 102 described later provided in the backlight 1.
  • a reflection sheet 103 is disposed inside the backlight chassis 10 in addition to the light guide plate 2, the light source unit 3, and the optical sheet 4 described above. Further, the edge side of the front side of the optical sheet 4 (liquid crystal panel unit side) is held by the chassis case 102.
  • the backlight chassis 10 is a box-shaped member whose front side (liquid crystal panel unit side) is open, and protrudes from a bottom 100 having a rectangular shape in plan view and four sides of the bottom 100. And a side wall 101.
  • the backlight chassis 10 can also be referred to as a frame member having a bottom 100.
  • a reflective sheet 103, a light guide plate 2, and an optical sheet 4 are arranged in this order on the bottom 100 of the backlight chassis 10. Further, the light source unit 3 is fixed inside the portion of the side wall 101 of the backlight chassis 10 that protrudes from the two long sides of the bottom 100.
  • the light guide plate 2 is formed by forming a transparent resin such as polymethyl methacrylate (PMMA) or polycarbonate into a flat plate shape.
  • a transparent resin such as polymethyl methacrylate (PMMA) or polycarbonate
  • PMMA polymethyl methacrylate
  • polycarbonate polycarbonate
  • the light guide plate 2 is a flat plate member having a rectangular shape in plan view.
  • the main surface facing the liquid crystal panel unit 6 is configured as a light exit surface 21, and one of the longitudinal side surfaces is configured as a light receiving surface 22 that receives light from the light source unit 3.
  • the light guide plate 2 when the incident angle exceeds the critical angle, the light is totally reflected and propagated into the light guide plate 2.
  • a texture pattern (not shown) is formed that reflects the totally reflected light so as to rise toward the light exit surface 21.
  • a lens-shaped pattern or a pattern printed with an ink having a higher refractive index than the light guide plate material is generally used.
  • the light that hits the embossed pattern changes its propagation angle when reflected (becomes smaller than the critical angle) and rises toward the exit slope 21.
  • the embossed pattern is provided with a phosphor. When the light rises in the embossed pattern, the light is excited by the phosphor and emitted from the light exit surface 21 as wavelength-converted light.
  • the backlight 1 is a lighting device that emits planar light, and the planar light preferably has a highly uniform luminance distribution. Therefore, the uniformity of the luminance distribution is controlled by adjusting the coverage of the embossed pattern.
  • the embossed pattern is a dot-like pattern having both a size and a thickness of 100 ⁇ m to 500 ⁇ m, and the coverage (the ratio occupied by the embossed pattern per unit area) is controlled from 0% to 100%.
  • the 1st opposing part 51 which opposes the light emission surface 21 is arrange
  • the light source unit 3 includes a long LED substrate 5 disposed to face the light receiving surface 22 and a plurality (eight) LEDs 31 arranged in a row on the LED substrate 5.
  • the LEDs 31 are arranged at equal intervals, but may be an arrangement in which the intervals are partially changed.
  • the light source unit 3 is attached to the backlight chassis 10, and the light emitted from the LEDs 31 enters from the light receiving surface 22 of the light guide plate 2. Details of the light source unit 3 and the LED substrate 5 will be described later.
  • the optical sheet 4 is emitted from the light exit surface 21 as an optical sheet member, a diffusion sheet 41 that diffuses the light emitted from the light exit surface 21 of the light guide plate 2, a brightness enhancement sheet (DBEF) 42 that improves brightness.
  • a prism sheet 43 is provided that aligns the direction of light, that is, changes the direction so that light entering obliquely faces the liquid crystal panel unit 6.
  • An optical sheet member having optical characteristics other than these may be used.
  • FIG. 3 is a front view of the light source unit used in the backlight according to the present invention
  • FIG. 4 is a sectional view of the light source unit shown in FIG. 3
  • FIG. 5 is a front view showing the arrangement of the backlight according to the present invention. It is.
  • the light source unit 3 includes eight LEDs 31 and an LED substrate 5 on which the eight LEDs 31 are mounted linearly.
  • the LED substrate 5 has a U-shaped cross section, and faces the first opposing portion 51 having a rectangular parallelepiped shape facing the front surface of the light guide plate 2 and the back surface 23 of the light guide plate 2.
  • a rectangular parallelepiped shaped second opposing portion 52, an LED mounting portion 53 on which the long side of the first opposing portion 51 and the long side of the second opposing portion 52 are connected and the LED 31 is mounted are provided.
  • the first facing portion 51 and the second facing portion 52 have a shape erected from one main surface of the LED mounting portion 53. Then, eight LEDs 31 are arranged at equal intervals in a portion sandwiched between the first facing portion 51 and the second facing portion 52 of the LED mounting portion 53.
  • a solder resist is formed as a protective film of the LED substrate 5 on the inner wall surfaces of the first facing portion 51 and the second facing portion 52 and the mounting surface of the LED mounting portion 53.
  • the solder resist is applied by a conventionally well-known method such as a photolithography method or a screen printing method.
  • the light source unit 3 and the light guide plate 2 are disposed inside a bottomed frame-like backlight chassis 10.
  • the light source unit 3 is disposed along the long side of the bottom portion 100 of the backlight chassis 10, the LED 31 mounted on the connecting portion 53 and the light receiving surface 22 face each other, and the first facing portion 51 emits light.
  • the surface 21 and the second facing portion 52 are disposed to face the surface opposite to the light exit surface 21. That is, the side surface on the long side of the light guide plate 2 is disposed so as to be surrounded by the light source unit 3.
  • the LED substrate 5 is arranged such that the inner wall surface of the first facing portion 51 and the inner wall surface of the second facing portion 52 are in contact with the light exit surface 21 and the back surface 23 of the light guide plate 2, respectively. Has been. By being formed in this way, light emitted from the LED 31 can be prevented from leaking from the gap between the LED substrate 5 and the light guide plate 2.
  • the light emitted from the LED 31 is prevented from leaking, it is possible to suppress the occurrence of uneven brightness in the planar light emitted from the backlight 1.
  • the light emitted from the LED 31 can be efficiently incident on the light receiving surface 22 of the light guide plate 2, the light use efficiency can be increased, and the energy consumed when the LED 31 emits light. (Electric power) can be reduced.
  • the LED board 5 is disposed in contact with the backlight chassis 10, heat from the LEDs 31 is transmitted to the backlight chassis 10 through the LED board 5. Since the LED substrate 5 is disposed so as to surround the LED 31, heat generated from the LED 31 is efficiently conducted to the LED substrate 5. Further, since the shape of the LED substrate 5 is U-shaped in cross section, it is possible to increase the area in contact with the bottom 100, the side wall 101, and the chassis case 102 of the backlight chassis 10. 5, the heat radiation to the backlight chassis 10 and the chassis case 102 is efficiently performed.
  • the length of the LED board 5 is formed shorter than the length of the light receiving surface 22 of the light-guide plate 2 in the longitudinal direction, it is not limited to this, It is the same length as the light receiving surface 22. Alternatively, it may be longer than the length of the light receiving surface 22 in the longitudinal direction.
  • the first facing portion 51 and the LED mounting portion 53, and the second facing portion 52 and the LED mounting portion 53 are described as an example, but the present invention is not limited thereto. It is good also as a structure which makes each separately and combines.
  • segmented into a longitudinal direction may be sufficient. Since the structure can be divided, the influence of the error of the member is reduced, so that the inspection process for manufacturing can be reduced.
  • a glass epoxy substrate is often used as a substrate for mounting LEDs.
  • Glass epoxy substrates have low thermal conductivity.
  • an LED substrate is manufactured with a glass epoxy substrate, the heat dissipation efficiency is low, and it may be difficult to efficiently suppress the temperature increase of the LED 31. Therefore, in the backlight of the present invention, an aluminum substrate is used in order to efficiently release the heat generated by the LED 31.
  • the configuration and shape are the same as those of the backlight according to the first embodiment, and detailed description thereof is omitted.
  • the thermal conductivity is 0.35 W / mK, but in the case of an aluminum substrate, it is 236 W / mK and has a thermal conductivity of about 500 times. .
  • fever which LED31 emits can be thermally radiated efficiently by utilizing the board
  • the thermal conductivity of copper is 390 W / mK, which is about 1.7 times that of aluminum, and the heat dissipation efficiency can be further increased by using a copper substrate.
  • the whole need not be aluminum or copper, and may be a substrate on which aluminum, copper, or a metal film having a higher thermal conductivity is formed on the surface of resin equipment. In that case, it is preferable that the structure facilitates heat conduction between the front surface and the back surface.
  • FIG. 6 is a front view showing a state before processing the LED substrate
  • FIG. 7 is a sectional view of the LED substrate shown in FIG. 6
  • FIG. 8 is a sectional view of the LED substrate after processing.
  • the LED substrate 5B is a substrate having a complicated shape such as a U-shaped cross section, and the manufacturing is simplified by the following method.
  • the unprocessed LED substrate 50b is a single metal substrate, the LED mounting portion 53b at the center, the first facing portion 51b and the LED mounting portion 53 on both sides in the short direction.
  • the second facing portions 52b are respectively disposed.
  • a notch 501 having a triangular cross section (right isosceles triangle) is formed in a portion between the LED mounting portion 53b and the first facing portion 51b.
  • a notch 502 having the same shape as the notch 501 is formed between the LED mounting portion 53b and the second facing portion 52b.
  • the first opposing portion 51b of the LED substrate 50 before processing is raised with the notch 501 as the center, and the second opposing portion 52b is raised with the notch 502 as the center, so that the cross section as shown in FIG. A U-shaped LED substrate 5B can be formed.
  • the LED substrate 5B is formed by a cutting process for forming a notch in a single metal substrate and a process (press process) for raising the first facing part 51b and the second facing part 52b. Since it can be manufactured, processing is easy, and it is possible to reduce the time and labor required for manufacturing. In addition, since the manufactured LED board 5B can rotate the 1st opposing part 51b and the 2nd opposing part 52b centering on notch 501,502, the attachment to the light-guide plate 2 becomes easy. Moreover, since the shape after manufacture is the same as the LED board of 1st Embodiment and 2nd Embodiment, about the effect, it is the same as 1st Embodiment and 2nd Embodiment.
  • a solder resist for protecting the LED substrate 5 is formed on the inner wall surfaces of the first facing portion 51, the second facing portion 52, and the LED mounting portion 53 of the LED substrate 5.
  • the LED substrate 5 is attached to the light guide plate 2 so as to surround the end portion on which the light receiving surface 22 is formed from three directions, and at least the first facing surface 51 and the second surface.
  • the facing surface 52 is disposed in contact with the light exit surface 21 and the back surface 23 of the light guide plate 2.
  • the light emitted from the LED 31 or the light propagated through the light guide plate 2 may be reflected by the first facing surface 51 or the second facing surface 52. Moreover, the light reflected by the light receiving surface 22 or the light propagated through the light guide plate 2 may be emitted from the light receiving surface 22. In this case, the light is incident on the surface on which the LED 31 of the LED mounting portion 53 is mounted. .
  • a solder resist is formed on the first opposing surface 51, the second opposing surface 52 and the inner wall surface of the LED mounting portion 53 of the LED substrate 5 on which light is incident, and the light is not reflected depending on the color of the solder resist. As a result, the light use efficiency decreases. Therefore, when a white solder resist that efficiently reflects light is used on the inner wall surface of the LED substrate 5, the light absorbed by the LED substrate 5 can be reduced and the light utilization rate can be increased.
  • a highly reflective white solder resist having a reflectance of 70% or more the amount of light absorbed by the LED substrate 5 is reduced, that is, the utilization factor of light emitted from the LED 31 is improved.
  • a white solder resist there are also a highly reflective white solder resist having a reflectance of 80% or more and a highly reflective white solder resist having a reflectance of 90% or more, and the light absorbed by using these highly reflective white resists. It is possible to reduce the ratio of light and to further improve the light use efficiency.
  • a solder resist having a high reflectance on the inner wall surface of the LED substrate 5 it is possible to increase the light use efficiency and reduce the energy (electric power) consumed when the LED 31 emits light. Is possible.
  • a white reflective layer is printed on the upper surface of a normal solder resist. May be formed. Even when the reflective layer is formed, it is possible to obtain the same light utilization efficiency as that for forming the highly reflective white solder resist.
  • FIG. 9 is an enlarged cross-sectional view of the LED substrate portion of the backlight according to the present invention.
  • the backlight 1 shown in FIG. 9 has the same configuration as that of the backlight 1 shown in FIG. 2 and the like except that the LED substrate 5C is different. Description is omitted.
  • the light incident on the inside of the light guide plate 2 propagates (diffuses) inside the light guide plate 2 while being repeatedly reflected.
  • the incident angle is determined by the refractive index of the light guide plate 2 and the refractive index of air.
  • Light incident at a larger angle is totally reflected at the boundary surface (side surface of the light guide plate 2), and the total amount of light propagates inside the light guide plate 2.
  • the LED substrate is a member that does not easily transmit light
  • the LED substrate 5C has a constant reflectance at the portion of the light guide plate 2 that contacts the LED substrate, but reflected light corresponding to the reflectance is generated. The remaining light that has not been reflected is absorbed by the LED substrate, and the light use efficiency decreases.
  • the contact area of the inner wall surface 511 of the first facing portion 51c, the inner wall surface 521 of the second facing portion 52c, that is, the surface facing the light guide plate 2 is reached. In order to reduce this, the surface is roughened.
  • the inner wall surface 511 of the first facing portion 51c and the inner wall surface 521 of the second facing portion 52c are roughened, so that the inner wall surface 511, the light exit surface 21, the inner wall surface 521, An air layer is formed between the back surface 23.
  • the incident angles of the light propagated in the light guide plate 2 and incident on the first facing portion 51c and the second facing portion 52c are larger than the critical angles determined by the respective refractive indexes of the light guide plate 2 and air.
  • the light is totally reflected by the light guide plate 2.
  • the light absorbed by the LED substrate 5C can be reduced, and the light use efficiency can be improved.
  • the inner wall surface of the 1st opposing part 51c and the 2nd opposing part 52c is roughened only the part facing the light emission surface 21 and the back surface 23 of the light-guide plate 2 (contact).
  • only the facing (contact) portion is roughened, so that the light emitted from the LED 31 and reaching the light receiving surface 22 reaches the first facing portion 51c or the second facing portion 52c. Reflected uniformly by the inner wall surfaces 511 and 521.
  • FIG. 10A is a cross-sectional view showing another example of the LED substrate
  • FIG. 10B is an enlarged cross-sectional view showing another example of the LED substrate.
  • the inner wall surface 511 of the first facing portion 51c and the inner wall surface 521 of the second facing portion 52c of the LED substrate 5C are in contact with the light emitting surface 21 and the back surface 23 only in the vicinity of the light receiving surface 22.
  • tip of the inner wall surface 511 and the inner wall surface 521 is formed so that it may leave
  • the light receiving surface 22 and the LED substrate 5C are in close contact with each other, and light leakage from the gap between the light receiving surface 22 and the LED substrate 5C is suppressed. Further, since an air layer is formed between the inner wall surface 511 and the light exit surface 21, and between the inner wall surface 521 and the rear surface 23, the light propagated inside the light guide plate 2 is totally reflected inside the light guide plate 2. Therefore, a decrease in light utilization efficiency can be suppressed.
  • support columns 512 and 522 that contact the light guide plate 2 may be formed on the light receiving surface 511 and the light receiving surface 521.
  • pillar part 512 is a column-shaped support
  • pillar part 522 is a plate-shaped support
  • the LED substrate 5 can be stably attached to the light guide plate 2 by providing the support columns 512 and 522.
  • pillar part 512 may be a plate-shaped support
  • pillar part 522 may be a column-shaped support
  • both may be a column shape, or both may be a column-shaped support
  • the contact area between the column part 512 and the light exit surface 21 and between the column part 522 and the back surface 23 is very small, it is difficult to affect the total reflection of the light propagated inside the light guide plate 2. Therefore, by providing the column portions 512 and 522, it is possible to stably attach the LED substrate 5C to the light guide plate 2, and it is possible to suppress a decrease in light utilization efficiency.
  • the column shape and the plate-like shape have been described as examples of the shape of the column portions 512 and 522, it is not limited to this, and a column with a small contact area with the surface of the light guide plate 2 is widely used. It is possible to adopt.
  • a double-sided pressure-sensitive adhesive sheet is used for fixing the LED substrate 5 and the backlight chassis 10.
  • the double-sided pressure-sensitive adhesive sheet is mostly formed of a resin, has a low thermal conductivity, and often becomes a thermal resistance between the LED substrate 5 and the backlight chassis 10.
  • the double-sided adhesive sheet between the LED substrate 5 and the backlight chassis 10 becomes a thermal resistance, and heat conduction is not performed so much.
  • the heat conducted from the LED 31 to the LED substrate 5 decreases, the temperature of the LED 31 increases, and the light emission efficiency of the LED 31 decreases.
  • heat is also conducted to the light guide plate 2 disposed close to the LED substrate 5, and the light guide plate 2 may be warped due to thermal deformation. It can also be a cause.
  • a double-sided pressure-sensitive adhesive sheet that has been often used conventionally has a thermal conductivity of 0.1 W / mK and a thermal resistance. Therefore, by using the heat conductive double-sided pressure-sensitive adhesive sheet having a heat conductivity of 1.0 W / mK, the heat dissipation efficiency is increased, and the temperature rise of the LED substrate 5 can be suppressed. Thereby, the temperature rise of LED31 can also be reduced and it can suppress that the luminous efficiency of LED31 falls. Moreover, since the temperature rise of the light-guide plate 2 can also be suppressed, it is possible to suppress light leakage that occurs when the light-guide plate 2 is warped. Further, by using a double-sided pressure-sensitive adhesive sheet having higher thermal conductivity, it is possible to further increase the heat radiation efficiency.
  • the LED substrate has the same length (width) in the short direction of the first facing portion and the length (width) in the short direction of the second facing portion, but is different.
  • the width of the second facing portion may be shorter than the width of the first facing portion.
  • the liquid crystal display device according to the present invention can be used for a television receiver, a PC monitor and the like.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)

Abstract

En vue de supprimer la perte de lumière depuis les DEL et la baisse d'efficacité d'émission de lumière des DEL sans augmenter le nombre d'éléments constitutifs, un rétro-éclairage comprend : une plaque de guidage de lumière (2) qui reçoit de la lumière d'une surface de réception de lumière (22) et qui émet une lumière plane depuis une surface d'émission de lumière (21) ; et un substrat de DEL (5) qui présente une section transversale en forme de C et qui comprend une partie de montage de DEL (53) comprenant une pluralité de DEL (31) montées sur celle-ci sous la forme de rangées, une première partie opposée (51) et une seconde partie opposée (52). Le substrat de DEL (5) est fixé sur la plaque de guidage de lumière (2) de sorte que la partie de montage de DEL (53) soit opposée à la surface de réception de lumière (22) et, en outre, la première partie opposée (51) vient en contact avec la surface émettant de la lumière (21) et la seconde partie opposée (52) vient en contact avec une surface arrière (23).
PCT/JP2012/067216 2011-08-01 2012-07-05 Rétro-éclairage et dispositif d'affichage à cristaux liquides WO2013018499A1 (fr)

Applications Claiming Priority (2)

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JP2011168519 2011-08-01
JP2011-168519 2011-08-01

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JP2016189413A (ja) * 2015-03-30 2016-11-04 大日本印刷株式会社 Ｌｅｄ実装モジュール及びｌｅｄ表示装置
US11931490B2 (en) 2018-10-05 2024-03-19 Seoul Viosys Co., Ltd. Air purification module and refrigerator comprising the same

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JP2009158315A (ja) * 2007-12-27 2009-07-16 Hitachi Ltd 光源モジュール
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JP2010146931A (ja) * 2008-12-22 2010-07-01 Minebea Co Ltd 線状光源装置、および面状照明装置
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JP2006310221A (ja) * 2005-05-02 2006-11-09 Matsushita Electric Ind Co Ltd エッジ入力型バックライト及び液晶表示装置
JP2009158315A (ja) * 2007-12-27 2009-07-16 Hitachi Ltd 光源モジュール
JP2009252419A (ja) * 2008-04-03 2009-10-29 Minebea Co Ltd 線状光源装置、および面状照明装置
JP2010092739A (ja) * 2008-10-08 2010-04-22 Sumitomo Electric Printed Circuit Inc 配線モジュール、その製造方法、および電子機器
JP2010146931A (ja) * 2008-12-22 2010-07-01 Minebea Co Ltd 線状光源装置、および面状照明装置
JP2010147012A (ja) * 2008-12-22 2010-07-01 Panasonic Electric Works Co Ltd 面光源装置および表示用照明器具
JP2010198792A (ja) * 2009-02-23 2010-09-09 More Tenso:Kk 照明装置付きの棚

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016189413A (ja) * 2015-03-30 2016-11-04 大日本印刷株式会社 Ｌｅｄ実装モジュール及びｌｅｄ表示装置
US11931490B2 (en) 2018-10-05 2024-03-19 Seoul Viosys Co., Ltd. Air purification module and refrigerator comprising the same

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