JP2010092777A - Planar light unit and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a dark area between LED light sources regardless of a thin light guide plate in a planar light unit and a display device. <P>SOLUTION: The planar light unit includes the light guide plate 2 and the LED light sources 3 disposed on an end face 2a on the base end side of the light guide plate 2. The LED light source 3 includes a substrate 4, an LED element mounted on the substrate 4, a seal resin part 6 for sealing the LED element onto the substrate 4 and making light from the LED element outgoing at least from a front opposed to the base end side end face and a pair of sides directed in a direction in which the base end side end face extends, and transparent resin parts 7 disposed at least on the pair of sides to guide or refract lights which have been made outgoing from the sides toward the light guide plate 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a planar light unit that illuminates a liquid crystal display panel or the like and a display device.

  Liquid crystal display devices for image display are widely used for displays such as mobile phones, notebook PCs (personal computers), car navigation devices, mobile type PCs, PDAs, and ATMs (automated teller machines). This liquid crystal display device uses a backlight unit that emits light from the back side of the liquid crystal display panel to increase the brightness of the display screen.

  The backlight unit includes, for example, a light guide plate and a light source of an LED light source or a fluorescent tube disposed on an end surface of the light guide plate, and guides light from the light source with the light guide plate to liquid crystal from the entire main surface. The light is emitted toward the display panel. In recent years, in particular, a sidelight type backlight unit in which an LED light source is disposed on an end face of a light guide plate is applicable to mobile phones and the like because it can cope with downsizing and thinning.

However, when an LED light source that is a point light source is arranged on the end face of the light guide plate, a dark portion D is generated between the LED light sources 101 of the light guide plate 102 due to the directivity of the LED light source 101 as shown in FIG.
As a countermeasure for this, for example, in Patent Document 1, conventionally, as shown in FIG. 16, an R-shaped or prism-shaped uneven portion 102a is formed on the light incident portion on the end face of the light guide plate 102, and is incident from the LED light source 101. A light guide plate is disclosed in which light is spread and the dark portion D is reduced.

Japanese Patent Laying-Open No. 2005-228718 (Claims, FIGS. 2 and 8)

However, the following problems remain in the conventional technology.
In recent years, since further thinning has been demanded, the use of a film light guide plate formed of a thin light guide film has increased. However, a thin light guide plate such as a film light guide plate is described in Patent Document 1. It was difficult to form a fine shape such as an uneven portion on the end face of the light guide plate as in the art. Moreover, in the conventional molded light guide plate, the dark part between the LED light sources can be reduced to some extent by forming the uneven part on the end face, but since the light spread by the uneven part is limited, There is a demand for further expanding the light to further reduce dark areas.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a planar light unit and a display device that can reduce dark portions between LED light sources even with a thin light guide plate.

  The present invention employs the following configuration in order to solve the above problems. That is, the planar light unit of the present invention includes a light guide plate and an LED light source disposed on the base end side end surface of the light guide plate, and the LED light source is mounted on the substrate and the LED. The LED element is sealed on the element, and the light from the LED element is emitted from at least a front surface facing the base end face and a pair of side faces facing the extending direction of the base end face. A sealing resin portion that is possible, and a translucent resin portion that is provided on at least the pair of side surfaces and guides or refracts light emitted from these side surfaces and emits the light to the light guide plate. And

  In this planar light unit, the LED light source includes a translucent resin portion that is provided on at least a pair of side surfaces of the sealing resin portion and guides or refracts light emitted from these side surfaces and emits the light to the light guide plate. Therefore, the light emitted from the side surface is expanded in the extending direction of the base end side end surface by the translucent resin portion and then emitted to the light guide plate, thereby widening the width of the incident light of the LED light source to the left and right. Thus, the dark portion of the light guide plate can be reduced without providing a fine shape to the light incident portion.

  The planar light unit of the present invention is characterized in that the light guide plate is formed of a light guide film. That is, in this planar light unit, since the light guide plate is formed of the light guide film, it can be significantly reduced in thickness and cost can be reduced as compared with the molded light guide plate.

  The planar light unit of the present invention is an adhesive that bonds the LED light source and the light guide plate by filling the translucent resin portion between the pair of side surfaces and the proximal end surface. It is characterized by being. That is, in this planar light unit, the translucent resin portion is filled between the pair of side surfaces of the sealing resin portion and the base end side end surface of the light guide plate to bond the LED light source and the light guide plate. Therefore, the light guide plate and the LED light source can be bonded and fixed by the translucent resin portion, positioning becomes easy, and assemblability is improved.

  The planar light unit of the present invention is characterized in that the translucent resin portion has a higher refractive index than the sealing resin portion. That is, in this planar light unit, since the translucent resin portion has a higher refractive index than the encapsulating resin portion, light is efficiently emitted from the encapsulating resin portion to the translucent resin portion, and thus the translucent resin. It is possible to increase the light incident efficiency from the portion to the light guide plate and improve the dark portion reduction effect.

  Further, in the planar light unit of the present invention, a concave portion for housing the LED light source is provided on the proximal end surface of the light guide plate, and the translucent resin portion includes the pair of side surfaces and the inner side surface of the concave portion. It is provided between. That is, in this planar light unit, since the translucent resin portion is provided between the pair of side surfaces of the LED light source housed in the recess and the inner surface of the recess, the light is emitted from the side surface of the sealing resin portion. The incident light enters the light guide plate also from the inner side surface of the recess through the translucent resin portion, so that the light can be further spread left and right.

  In the planar light unit of the present invention, the translucent resin portion is also provided between the front surface of the sealing resin portion and the base end side end surface. That is, in this planar light unit, since the translucent resin portion is also provided between the front surface of the sealing resin portion and the base end side end surface, the front surface of the sealing resin portion and the base end side end surface The gap is filled with the translucent resin portion, and the air layer is eliminated, so that reflection loss due to the interface can be reduced.

  Further, in the planar light unit of the present invention, a plurality of the LED light sources are installed at intervals on the base end side end surface, and the translucent resin portion is disposed on the sealing resin portion of the adjacent LED light source. It is provided between the side surfaces to connect these LED light sources. That is, in this planar light unit, since the translucent resin portion is provided between the side surfaces of the sealing resin portions of the adjacent LED light sources and connects these LED light sources, the light is emitted from the side surface of the sealing resin portion. Since the emitted light is guided between the LED light sources connected by the translucent resin portion and emitted as linear light, the incident light can be further spread and the dark portion of the light guide plate can be reduced.

  The display device of the present invention includes an image display panel and the planar light unit of the present invention disposed on the front surface side or the back surface side of the image display panel. In other words, the display device includes the planar light unit of the present invention arranged on the front surface side or the back surface side of the image display panel, so that the entire device can be thinned, and the dark portion is reduced and the luminance is reduced. High-quality image display can be obtained by highly uniform illumination.

  In the display device of the present invention, the image display panel is a liquid crystal display panel. That is, since this display device is a liquid crystal display device using a liquid crystal display panel, it is possible to further reduce the thickness and weight of the entire device and reduce the cost, and to obtain a high-quality liquid crystal display.

The present invention has the following effects.
That is, according to the planar light unit according to the present invention, the LED light source is provided on at least a pair of side surfaces of the sealing resin portion, and light emitted from these side surfaces is guided or refracted and emitted to the light guide plate. Since the light-sensitive resin portion is provided, the width of the incident light of the LED light source can be expanded to the left and right, and the dark portion of the light guide plate can be reduced without providing a fine shape to the light incident portion. Therefore, according to the display device provided with the planar light unit, the entire device can be thinned, and a dark portion is reduced, and high-quality image display can be obtained by illumination with high luminance uniformity.

  Hereinafter, a planar light unit and a display device according to a first embodiment of the present invention will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size.

The backlight unit (planar light unit) 1 in the present embodiment is disposed with a space between the light guide plate 2 and the base end side end surface 2a of the light guide plate 2 as shown in FIGS. A plurality of LED light sources 3.
The LED light source 3 is, for example, a white LED, and as shown in FIG. 3, the substrate 4, the LED element 5 mounted on the substrate 4, and the LED element 5 is sealed on the substrate 4 and the LED element 5 is sealed. A sealing resin portion 6 capable of emitting light from the LED element 5 from at least a front surface 6a facing the proximal end surface 2a and a pair of side surfaces 6b facing the extending direction of the proximal end surface 2a, and a pair of side surfaces 6b And a translucent resin portion 7 that guides and refracts the light emitted from the side surface 6 b and emits the light to the light guide plate 2.

The LED element 5 is, for example, a blue (wavelength λ: 470 to 490 nm) LED element or an ultraviolet light (wavelength λ: less than 470 nm) LED element, for example, a gallium nitride compound semiconductor (on a insulating substrate such as a sapphire substrate). For example, a plurality of semiconductor layers of InGaN-based compound semiconductor) are stacked.
The sealing resin portion 6 is mainly composed of a silicone resin and, for example, a YAG phosphor is added. This YAG phosphor converts white light or ultraviolet light from an LED element into yellow light and generates white light by a color mixing effect. Various white LEDs other than those described above can be used.

  As another example of the LED light source 3, as shown in FIGS. 4 and 5, the LED light source 3 A provided with the reflection frame 8 on the upper and lower surfaces of the sealing resin portion 6, or only on the upper surface of the sealing resin portion 6. You may employ | adopt LED light source 3B which provided the reflective frame 8. FIG. In addition, the said reflective frame 8 has the reflective surface which reflects the light from the sealing resin part 6 inside, for example, is formed with the white resin material.

  The light guide plate 2 is made of a translucent resin material such as polycarbonate resin or acrylic resin, and a film light guide plate formed of a light guide film is employed in the present embodiment.

The translucent resin portion 7 is an adhesive that is filled between the pair of side surfaces 6 b of the sealing resin portion 6 and the base end side end surface 2 a of the light guide plate 2 and adheres the LED light source 3 and the light guide plate 2. is there.
The translucent resin portion 7 is formed of a curable resin having a higher refractive index than that of the sealing resin portion 6 such as a thermosetting resin or a UV curable resin.
In addition, between the front surface 6a of the sealing resin part 6 and the base end side end surface 2a of the light-guide plate 2, there is no translucent resin part 7, and it is set as the air layer.

Further, as shown in FIG. 6, the backlight unit 1 includes a diffusion sheet 9 that is disposed on the light guide plate 2 and diffuses light from the light guide plate 2 to make the in-plane light intensity uniform, and the diffusion sheet 9. A first prism sheet 11A and a second prism sheet 11B that are arranged above and emit light from the diffusion sheet 9 as upward irradiation light toward the liquid crystal display panel (image display panel) 10; And a reflection sheet 12 disposed on the surface.
In the present embodiment, the screen side of the liquid crystal display panel 10 and the light emission surface side of the backlight unit 1 are described as the surface side or the upper surface side.

  The diffusion sheet 9 is a sheet in which silica particles or the like are dispersed in a transparent resin such as an acrylic resin or a polycarbonate resin.

  The first prism sheet 11A is disposed on the diffusion sheet 9, and the second prism sheet 11B is disposed on the first prism sheet 11A. The first prism sheet 11A and the second prism sheet 11B are transparent sheet-like members for condensing light from the diffusion sheet 9 on the upper surface side, and have a prism portion having a plurality of parallel ridge lines on the upper surface side. is doing. In addition, the first prism sheet 11A has the ridge line of the prism portion set at a twisted position with respect to the optical axis of the LED light source 3, and in particular, the light of the LED light source 3 as a direction in which high upward directivity is obtained. It is set parallel to the direction orthogonal to the axis. Further, in the second prism sheet 11 </ b> B, the ridge line of the prism portion is set parallel to the optical axis of the LED light source 3. That is, the first prism sheet 11A and the second prism sheet 11B are arranged such that the ridge lines of the prism portions are twisted and the ridge lines are orthogonal to each other in plan view.

  The reflection sheet 12 is a metal plate, film, foil or the like having a light reflection function, and in this embodiment, a film provided with a silver vapor deposition film is employed. Note that an aluminum metal vapor deposition film or the like may be employed instead of the silver vapor deposition film. The reflection sheet 12 is affixed to a holder or the like (not shown) that houses each sheet of the backlight unit 1.

  Further, the display device 20 of the present embodiment is a liquid crystal display device applied to a liquid crystal display such as a mobile phone, a notebook PC, a car navigation device, a mobile type PC, a PDA, an ATM, etc. And the backlight unit 1 disposed on the back side of the liquid crystal display panel 10.

  The liquid crystal display panel 10 is a transmissive or transflective liquid crystal display panel. For example, in the case of the transmissive liquid crystal display panel 10, a TFT liquid crystal method, an STN liquid crystal method, or a TN device in which a liquid crystal material is sealed in a gap between an upper substrate and a lower substrate each having a transparent electrode, an alignment film, and a polarizing plate. A panel body such as a liquid crystal system is provided.

  In the backlight unit 1 of the present embodiment, the LED light source 3 is provided on the pair of side surfaces 6b of the sealing resin portion 6 and transmits light radiated and refracted from the side surfaces 6b to be emitted to the light guide plate 2. Since the light-sensitive resin portion 7 is provided, the light emitted from the side surface 6 b is spread by the light-transmissive resin portion 7 in the extending direction of the base end side end surface 2 a and then emitted to the light guide plate 2. That is, the emission surface of the LED light source 3 is apparently spread left and right by the translucent resin portion 7. Therefore, the width of the incident light of the LED light source 3 can be widened to the left and right, and the dark portion D of the light guide plate 2 can be reduced without giving a fine shape to the light incident portion.

The translucent resin portion 7 is an adhesive that is filled between the side surface 6 b of the sealing resin portion 6 and the base end side end surface 2 a of the light guide plate 2 to adhere the LED light source 3 and the light guide plate 2. Therefore, the light guide plate 2 and the LED light source 3 can be bonded and fixed by the translucent resin portion 7, positioning becomes easy, and assemblability is improved.
Further, since the translucent resin portion 7 has a higher refractive index than the sealing resin portion 6, light is efficiently emitted from the encapsulating resin portion 6 to the translucent resin portion 7, and from the translucent resin portion 7. The light incident efficiency to the light guide plate 2 can be increased and the effect of reducing the dark portion D can be improved.
In addition, since the light guide plate 2 is formed of the light guide film, the thickness can be significantly reduced as compared with the molded light guide plate, and the cost can be reduced.

  Therefore, in the display device 20 including the backlight unit 1 of the present embodiment, the entire device can be thinned, and the dark portion D is reduced, and high-quality image display is obtained by illumination with high luminance uniformity.

  Next, second to sixth embodiments of the planar light unit and the display device according to the present invention will be described below with reference to FIGS. In the following description of each embodiment, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that in the first embodiment, the base end side end surface 2a of the light guide plate 2 is a straight flat surface, whereas the backlight unit of the second embodiment. In the (planar light unit) 21, as shown in FIGS. 7 and 8, a recess 22 b that houses the LED light source 3 is provided on the proximal end surface 22 a of the light guide plate 22, and the translucent resin portion 27 is sealed. It is a point provided between the pair of side surfaces 6b of the stop resin portion 6 and the inner surface of the recess 22b.

  That is, in 2nd Embodiment, the rectangular shaped recessed part 22b is formed in the base end side end surface 22a, the LED light source 3 is distribute | arranged in the recessed part 22b, and both the side surfaces 6b and the inner surface of the recessed part 22b are translucent. Bonded with the conductive resin portion 27. This translucent resin portion 27 is cured by filling a liquid curable resin in the space between the side surface 6b of the sealing resin portion 6 and the inner side surface of the recess 22b with the LED light source 3 disposed in the recess 22b. To make it.

  Thus, in 2nd Embodiment, since the translucent resin part 27 is provided between a pair of side surface 6b in the LED light source 3 accommodated in the recessed part 22b, and the inner surface of the recessed part 22b, sealing resin The light emitted from the side surface 6b of the portion 6 is also incident on the light guide plate 22 through the translucent resin portion 27 from the inner side surface of the recess 22b, so that the light can be further spread left and right. That is, the translucent resin portion 27 also functions as a light guide portion that guides light emitted from the side surface 6 b and enters the inner surface of the recess 22 b, so that the light guide plate 22 can be viewed from the left and right sides of the LED light source 3. The amount of light entering can be increased.

  The difference between the third and fourth embodiments and the first embodiment is that, in the first embodiment, an air layer is formed between the front surface 6a of the sealing resin portion 6 and the base end side end surface 2a of the light guide plate 2. In contrast, in the backlight units (planar light units) 31 and 41 of the third and fourth embodiments, as shown in FIG. 9 and FIG. This is that not only the side surface 6b of the sealing resin part 6 but also the front surface 6a of the sealing resin part 6 and the base end side end faces 2a and 22a are filled with a resin material.

  That is, in 3rd and 4th embodiment, since the translucent resin parts 37 and 47 are provided also between the front surface 6a and the base end side end surface 2a of the sealing resin part 6, sealing resin part 6, the space between the front surface 6a and the base end side end surface 2a is filled with the translucent resin portions 37 and 47, the air layer is eliminated, and reflection loss due to the interface can be reduced.

  The difference between the fifth embodiment and the first embodiment is that, in the first embodiment, the translucent resin portion 7 is individually provided for each of the plurality of LED light sources 3 installed at intervals on the proximal end surface 2a. In contrast, in the backlight unit (planar light unit) 51 of the fifth embodiment, as shown in FIGS. 11 and 12, the translucent resin portion 57 seals the adjacent LED light source 3. The LED light source 3 is connected between the side surfaces 6 b of the resin portion 6.

That is, in the fifth embodiment, the LED light sources 3 arranged in a straight line and adjacent to each other are joined to each other by the translucent resin portion 57 to form a rod-like linear light source as a whole and arranged close to the proximal end surface 2a. Has been.
Therefore, in 5th Embodiment, since the translucent resin part 57 is provided between the side surfaces 6b of the sealing resin part 6 of the LED light source 3 which adjoins, and these LED light sources 3 are connected, sealing resin part The light emitted from the side surface 6 b of the light guide 6 is guided between the LED light sources 3 connected by the translucent resin portion 57 and emitted as linear light, so that the incident light is further expanded to darken the light guide plate 2. D can be reduced.

  The difference between the sixth embodiment and the fifth embodiment is that, in the fifth embodiment, the LED light sources 3 that are connected to each other by a light-transmitting resin portion 57 to form a linear light source are close to the proximal end surface 2a. In contrast, in the backlight unit (planar light unit) 61 of the sixth embodiment, as shown in FIGS. 13 and 14, the translucent resin portion 67 is bonded to the base end side end surface 2a. Thus, the LED light source 3 and the connected LED light source 3 are fixed to the proximal end surface 2a.

  That is, in 6th Embodiment, since the LED light source 3 connected by the translucent resin part 67 is adhere | attached on the base end side end surface 2a, the light-guide plate 2 and LED are similar to 1st-4th embodiment. The light source 3 can be fixed by the translucent resin portion 67, and positioning becomes easy and the incorporation is improved.

In addition, this invention is not limited to said each embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in each of the embodiments described above, it is preferable to form the translucent resin portion with an adhesive as described above. However, the translucent resin portion is prepared in advance as a molded resin member and is adhered or adhered to the sealing resin portion. It may be provided.

Moreover, in the backlight unit of each said embodiment, although the diffusion sheet is used, it is good also as a backlight unit which abbreviate | omitted the diffusion sheet. In addition, although two prism sheets are used, a backlight unit employing one prism sheet may be used.
In the display device of each of the above embodiments, a liquid crystal display panel is adopted as the image display panel, but other image display panels may be used. For example, an image display panel such as electronic paper may be employed. In this case, the planar light unit of the present invention is installed as a front light unit on the front side of the electronic paper main body.

In 1st Embodiment of the planar light unit and display apparatus which concern on this invention, it is a top view which shows the light-guide plate and LED light source in a backlight unit. In 1st Embodiment, it is an enlarged plan view of the principal part which shows the light-guide plate and LED light source in a backlight unit. In 1st Embodiment, it is the top view which shows an LED light source, a front view, a bottom view, and a side view. In 1st Embodiment, it is the top view which shows the other example of an LED light source, a front view, a bottom view, and a side view. In 1st Embodiment, it is the top view which shows the other example of an LED light source, a front view, a bottom view, and a side view. In 1st Embodiment, it is sectional drawing which shows a backlight unit and a display apparatus. In 2nd Embodiment of the planar light unit and display apparatus which concern on this invention, it is a top view which shows the light-guide plate and LED light source in a backlight unit. In 2nd Embodiment, it is an enlarged plan view of the principal part which shows the light-guide plate and LED light source in a backlight unit. In 3rd Embodiment of the planar light unit and display apparatus which concern on this invention, it is an enlarged plan view of the principal part which shows the light-guide plate and LED light source in a backlight unit. In 4th Embodiment of the planar light unit and display apparatus which concern on this invention, it is an enlarged plan view of the principal part which shows the light-guide plate and LED light source in a backlight unit. In 5th Embodiment of the planar light unit and display apparatus which concern on this invention, it is a top view which shows the light-guide plate and LED light source in a backlight unit. In 5th Embodiment, it is an enlarged plan view of the principal part which shows the light-guide plate and LED light source in a backlight unit. In 6th Embodiment of the planar light unit and display apparatus which concern on this invention, it is a top view which shows the light-guide plate and LED light source in a backlight unit. In 6th Embodiment, it is an enlarged plan view of the principal part which shows the light-guide plate and LED light source in a backlight unit. In the conventional example of the planar light unit and display apparatus which concern on this invention, it is a top view which shows the light-guide plate and LED light source in a backlight unit. In the conventional example of the planar light unit and display apparatus which concern on this invention, it is a top view which shows the light-guide plate and LED light source in a backlight unit.

Explanation of symbols

  1, 21, 31, 41, 51, 61 ... Backlight unit (planar light unit), 2, 22, 102 ... Light guide plate, 2a, 22a ... Base end side end face of light guide plate, 3, 101 ... LED light source, DESCRIPTION OF SYMBOLS 4 ... Board | substrate, 5 ... LED element, 6 ... Sealing resin part, 6a ... Front surface of sealing resin part, 6b ... Side surface of sealing resin part, 7, 27, 37, 47, 57, 67 ... Translucent resin , 10 ... Liquid crystal display panel (image display panel), 20 ... Display device, 22b ... Recessed portion of light guide plate

Claims (9)

A light guide plate;
An LED light source disposed on the proximal end surface of the light guide plate,
The LED light source comprises a substrate;
LED elements mounted on the substrate;
The LED element is sealed on the substrate and at least light from the LED element is sealed from a front surface facing the base end face and a pair of side faces extending in the extending direction of the base end face. Stop resin part,
A planar light unit comprising: a translucent resin portion that is provided on at least the pair of side surfaces and guides or refracts light emitted from the side surfaces and emits the light to the light guide plate. In the planar light unit according to claim 1,
The planar light unit, wherein the light guide plate is formed of a light guide film. In the planar light unit according to claim 1 or 2,
The planar light unit, wherein the translucent resin portion is an adhesive that is filled between the pair of side surfaces and the base end side end surface to bond the LED light source and the light guide plate. In the planar light unit according to any one of claims 1 to 3,
The planar light unit, wherein the translucent resin portion has a higher refractive index than the sealing resin portion. In the planar light unit according to any one of claims 1 to 4,
A concave portion for accommodating the LED light source is provided on the base end side end surface of the light guide plate,
The planar light unit, wherein the translucent resin portion is provided between the pair of side surfaces and an inner side surface of the recess. In the planar light unit according to any one of claims 1 to 5,
The planar light unit, wherein the translucent resin portion is also provided between the front surface of the sealing resin portion and the end surface on the base end side. In the planar light unit according to any one of claims 1 to 6,
A plurality of the LED light sources are installed at intervals on the proximal end surface,
The planar light unit, wherein the translucent resin portion is provided between the side surfaces of the sealing resin portions of the adjacent LED light sources to connect the LED light sources. An image display panel;
A planar light unit according to any one of claims 1 to 7, which is disposed on a front side or a back side of the image display panel. The display device according to claim 8, wherein
The display device, wherein the image display panel is a liquid crystal display panel.

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