JP5665623B2 - Surface light unit - Google Patents

Description

  The present invention relates to a planar light unit used for illumination such as a backlight of a liquid crystal display panel.

  Liquid crystal display devices for displaying images are widely used for displays such as notebook PCs (personal computers), car navigation devices, mobile type PCs, mobile phones, 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.

  In this backlight unit, a type using a light guide plate that guides light from a light source such as a fluorescent tube or an LED and emits the light from the entire main surface toward the liquid crystal display panel is known. There has been proposed a hollow surface illumination device that emits light into a space between a light reflecting surface member and a light emitting surface member without using a light guide plate, and reflects and diffuses the light.

  For example, in Patent Documents 1 and 2, a light reflecting member is disposed on the bottom side of a hollow unit case, a light emitting surface member is disposed on the front side of the unit case facing the light reflecting member, and the light reflecting member and the light emitting surface member are disposed. The space between the LED and the hollow light guide region, an LED light source in which a large number of LEDs are arranged and mounted on the wiring board is arranged adjacent to the hollow light guide region and emitted to the hollow light guide region, There has been proposed a hollow illuminating device in which an LED collimator for condensing light from an LED light source is disposed at an emission part of the LED light source. In these hollow illuminating devices, a light emitting surface member formed by stacking a light transmission diffusion plate, a diffusion sheet, and a lens sheet is used.

JP 2008-60061 A JP 2008-300194 A

However, the following problems remain in the conventional technology.
That is, in the hollow illuminating devices described in Patent Documents 1 and 2, since a diffuser plate that has a low light transmittance and is a heavy object is used, a reduction in luminance is unavoidable and an increase in weight and member costs are caused. There was a disadvantage of inviting. For this reason, if the light emitting surface side is configured with only another optical sheet without using a diffusion plate, there is no diffusion plate that has also functioned as a sheet receiver, so that the rigidity is insufficient and the sheets such as the diffusion sheet are bent. In addition to this, there is a problem that brightness unevenness and the like occur.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a planar light unit that can improve luminance without using a diffusion plate and can prevent bending of sheets. And

  The present invention employs the following configuration in order to solve the above problems. That is, the planar light unit of the first invention includes a reflection sheet, a sheet support member installed on the reflection sheet, a diffusion sheet installed on the sheet support member, and at least one side of the reflection sheet And a plurality of light sources that irradiate light to the space between the reflection sheet and the diffusion sheet or the sheet support member, and the sheet support member fixes the diffusion sheet over the entire outer periphery thereof. It is characterized by that.

  In this planar light unit, since the sheet support member fixes the diffusion sheet over the entire outer peripheral portion thereof, the sheet support member can cover the entire outer peripheral portion of the diffusion sheet (each side of the diffusion sheet) without the diffusion plate. By receiving and holding the tensioned state firmly, bending can be prevented. Further, since there is no diffusion plate, it is possible to improve the luminance, reduce the weight and reduce the member cost.

A planar light unit according to a second invention is characterized in that, in the first invention, the sheet support member is a support frame extending along an outer peripheral portion of the diffusion sheet.
That is, in this planar light unit, since the sheet support member is a support frame extending along the outer peripheral portion of the diffusion sheet, the frame-shaped support member holds the outer peripheral portion of the diffusion sheet and corresponds to the light emitting surface region. In addition, since there is a window portion opened, there is no reduction in luminance due to the support frame, and the weight can be reduced.

A planar light unit according to a third aspect of the present invention is the planar light unit according to the first aspect, wherein the sheet support member is disposed between a pair of support portions erected on two opposite sides of the reflective sheet and the pair of support portions. It is comprised with the transparent board part spanned across the said reflection sheet and spaced apart, and it is characterized by the above-mentioned.
In other words, in this planar light unit, the sheet support member has a pair of support portions erected on the two opposite sides of the reflection sheet, and is spanned between the pair of support portions with a space on the reflection sheet. Since it is composed of a transparent plate portion arranged , high rigidity is obtained, and light is hardly attenuated by transmitting light through the transparent plate portion formed of a transparent material, thereby suppressing a decrease in luminance. be able to.

In a planar light unit according to a fourth aspect of the present invention, in any one of the first to third aspects, the sheet support member includes a light blocking portion that covers the upper side of the plurality of light sources and blocks light from the light sources. It is characterized by that.
That is, in this planar light unit, the sheet support member has a light shielding part that covers the upper side of the plurality of light sources and shields the light from the light sources, so that the light is emitted toward the upper side of the light sources by the light shielding part. It is possible to prevent light from leaking from other than the light emitting surface area by shielding the light.

A planar light unit according to a fifth invention is characterized in that, in the second invention, the sheet support member is formed of a white material.
That is, in this planar light unit, since the sheet support member is formed of a white material, the light applied to the sheet support member having a white surface is reflected and diffused, so that the luminance can be improved.

A planar light unit according to a sixth aspect of the present invention is the planar light unit according to any one of the first to fifth aspects, wherein the light source is an LED, and the light source is arranged on the light emission surface side of the plurality of light sources, and the light sources are arranged. A collimator lens that extends along the direction and collects light emitted from the light source is provided.
That is, in this planar light unit, a collimator lens that is installed on the light emitting surface side of a plurality of light sources that are LEDs and extends along the arrangement direction of the light sources to collect the light emitted from the light sources is provided. As a result, light from a plurality of LEDs arranged side by side becomes band-like light collected by a collimator lens, and the influence of the point light source by each LED is reduced, and good surface light with less luminance unevenness is obtained. Can be obtained.

The present invention has the following effects.
That is, according to the planar light unit according to the present invention, since the sheet support member fixes the diffusion sheet over the entire outer peripheral portion thereof, it is possible to prevent the diffusion sheet from bending even without the diffusion plate, It is possible to improve luminance, reduce weight, and reduce member costs.
Therefore, the liquid crystal display device or lighting device provided with the planar light unit can be a high-intensity, lightweight, and low-cost device.

In 1st Embodiment of the planar light unit which concerns on this invention, it is a disassembled perspective view which shows a planar light unit. In 1st Embodiment, it is an expanded sectional view of the principal part which shows the light source periphery. In 2nd Embodiment of the planar light unit which concerns on this invention, it is a disassembled perspective view which shows a planar light unit.

  Hereinafter, a first embodiment of a planar light unit according to the present invention will be described with reference to FIGS. 1 and 2.

  The planar light unit 1 in the present embodiment is used, for example, in a backlight unit of a liquid crystal display panel. As shown in FIGS. 1 and 2, a box-shaped back case 2 having an upper opening, The reflection sheet 3 installed on the bottom surface of the back case 2, the sheet support member 4 installed on the reflection sheet 3, the diffusion sheet 5 installed on the sheet support member 4, and the diffusion sheet 5 The first prism sheet 6A and the second prism sheet 6B installed on the prism sheet, the polarizing sheet 7 installed on the prism sheet, and a frame-like shape having a light emitting surface area installed on the polarizing sheet 7 as a window portion. A front case 8 and a plurality of light sources L arranged side by side on at least one side of the reflection sheet 3 and irradiating light between the reflection sheet 3 and the diffusion sheet 5 or the sheet support member 4; The strip-shaped flexible printed circuit board 9 on which the plurality of light sources L are mounted, and the light that is installed on the light emission surface side of the plurality of light sources L and that extends along the direction in which the light sources L are arranged and is emitted from the light sources L And a collimator lens 10 for condensing the light.

In the present embodiment, the light emission surface side on the front case 8 side is described as the front surface side or the upper surface side.
The sheet support member 4 is a square frame-shaped support member that extends along the outer peripheral portion (four sides) of the diffusion sheet 5. The sheet support member 4 is formed of a white material resin.
Moreover, the sheet | seat support member 4 is fixing the diffusion sheet 5 over the whole outer peripheral part. That is, the diffusion sheet 5 is bonded and fixed on the sheet supporting member 4 by a double-sided tape (not shown) over the entire outer peripheral portion (all four sides).

Further, the sheet support member 4 has a light shielding portion 4a that covers the upper side of the plurality of light sources L and shields light from the light sources. The light shielding portion 4 a is formed in a strip shape wider than the width of the collimator lens 10 so as to cover the upper side of the collimator lens 10.
The sheet support member 4 is preferably formed of a white material as described above, but may be made of metal.
The side surface of the sheet support member 4 on the light shielding portion 4a side is notched to provide a space in which the flexible printed circuit board 9 and the collimator lens 10 on which the plurality of light sources L are mounted can be installed.

  The light source L is an LED light source, and a white LED is adopted in the present embodiment. This white LED is, for example, a semiconductor light emitting element on a substrate sealed with a resin material. As the semiconductor light emitting element, for example, a blue (wavelength λ: 470 to 490 nm) LED element or ultraviolet light (wavelength λ: less than 470 nm). An LED element is formed by laminating a plurality of semiconductor layers of a gallium nitride compound semiconductor (for example, an InGaN compound semiconductor) on an insulating substrate such as a sapphire substrate. The resin material 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 a semiconductor light emitting element into yellow light and generates white light by a color mixing effect. Various white LEDs other than those described above can be used.

The flexible printed circuit board 9 on which the plurality of light sources L are mounted is bonded to one of the inner wall surfaces of the back case 2 via a heat transfer tape 11. The heat transfer tape 11 is used for holding the flexible printed circuit board 9 and radiating heat from the light source L.
The flexible printed board 9 preferably uses a white resist. In this case, the leaked light is reflected as white light by the white resist of the flexible printed circuit board 9 and contributes to an improvement in luminance.

  As the reflection sheet 3, a metal plate having a light reflection function, a film, a foil, a film provided with a silver vapor deposition film, a film provided with an aluminum metal vapor deposition film, a white sheet, or the like can be adopted. For example, a reflective film having a multilayer film structure using a polyester resin is used.

  The first prism sheet 6A is disposed on the diffusion sheet 5, and the second prism sheet 6B is disposed on the first prism sheet 6A. The first prism sheet 6A and the second prism sheet 6B are transparent sheet-like members for condensing light from the diffusion sheet 5 on the upper surface side, and have a prism portion having a plurality of parallel ridge lines on the upper surface side. doing. Further, the first prism sheet 6A has the ridge line of the prism portion set at a twisted position with respect to the optical axis of the light source L, and in particular, the optical axis of the light source L as a direction in which high upward directivity is obtained. It is set parallel to the orthogonal direction.

  In the second prism sheet 6B, the ridge line of the prism portion is set parallel to the optical axis of the light source L. That is, the first prism sheet 6A and the second prism sheet 6B 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. As such first prism sheet 6A and second prism sheet 6B, for example, a BEF (Brightness Enhancement Firm: trade name) sheet manufactured by Sumitomo 3M Co., Ltd. can be employed.

  The polarizing sheet 7 is a reflective polarizing film that transmits only one of the S component and P component of light and reflects the other. The reflected component light returns to the reflective sheet side and is converted into component light that passes through the reflective polarizing film before entering the reflective polarizing film again. As such a reflective polarizing film, for example, a D-BEF (trade name) sheet manufactured by Sumitomo 3M Limited can be used. An absorptive polarizing sheet may be adopted as the polarizing sheet 7.

  The collimator lens 10 has a groove 10a having a rectangular cross section that can accommodate a plurality of light sources L along the extending direction, and has a tip having an arcuate cross section protruding in the optical axis direction of the light source L. This is a rod-shaped lens. For this reason, the collimating lens 10 can be easily formed by extrusion, has high productivity and low cost. By this collimating lens 10, the light emitted from the plurality of light sources L is condensed at an emission angle of 10 ° in the vertical direction, for example. The light thus collected is reflected by the reflection sheet 3 and diffused through the diffusion sheet 5, and passes through the first prism sheet 6 </ b> A, the second prism sheet 6 </ b> B, and the polarization sheet 7, and the window portion (light emission) of the front case 8. The light is emitted upward from the surface area.

  Thus, in the planar light unit 1 of the present embodiment, the sheet support member 4 fixes the diffusion sheet 5 over the entire outer peripheral portion thereof, so that the sheet support member 4 is the diffusion sheet 5 even without a diffusion plate. By receiving the entire outer peripheral portion (each side of the diffusion sheet 5) and holding the stretched state firmly, bending can be prevented. Further, since there is no diffusion plate, it is possible to improve the luminance, reduce the weight and reduce the member cost.

Further, since the sheet support member 4 is a support frame extending along the outer peripheral portion of the diffusion sheet 5, the frame-shaped support member holds the outer peripheral portion of the diffusion sheet 5 and is opened corresponding to the light emitting surface region. By having the window portion, there is no decrease in luminance due to the support frame, and the weight can be reduced.
Further, since the sheet support member 4 includes the light shielding part 4a that covers the upper side of the plurality of light sources L and shields the light from the light source L, the light emitted toward the upper side of the light source L by the light shielding part 4a. Can be prevented from leaking from other than the light emitting surface region.

In addition, since the sheet support member 4 is formed of a white material, the light applied to the sheet support member 4 having a white surface is reflected and diffused, so that the luminance can be improved.
Further, the collimator lens 10 is provided on the light emitting surface side of the plurality of light sources L that are LEDs and extends along the arrangement direction of the light sources L to collect the light emitted from the plurality of light sources L. Therefore, the light from a plurality of LEDs arranged side by side is condensed by the collimator lens 10 to form strip-shaped light, and the influence of the point light source by each LED is reduced, and good planar light with less luminance unevenness is obtained. Can be obtained.

  Next, a second embodiment of the planar light unit according to the present invention will be described below with reference to FIG. Note that, in the following description of the embodiment, the same components 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 sheet support member 4 is a square frame-shaped support member, whereas the planar light unit 21 of the second embodiment is different from the first embodiment. 3, the sheet support member 24 includes a pair of support portions 24 a erected on two opposite sides of the reflection sheet 3 and a pair of support portions 24 a so as to be placed on the reflection sheet 3. It is a point comprised by the transparent plate part 24b distribute | arranged at intervals.

That is, in 2nd Embodiment, the sheet | seat support member 24 is formed with transparent resin, such as an acrylic resin, and light is irradiated to the diffusion sheet 5 through the transparent plate part 24b.
The pair of support portions 24a is formed on the opposite two sides excluding the side where the light source L and the collimator lens 10 are arranged. In addition, you may provide the support part 24a also in the side opposite to the side where the light source L and the collimator lens 10 are arrange | positioned. Further, a reflective tape such as a white tape or a silver tape is attached to the side of the light source L side of the transparent plate portion 24b as a light shielding portion 24c above the light source L and the collimator lens 10.
Furthermore, the back case 22 of the second embodiment is not box-shaped, but is composed of only one wall surface on which the flexible printed circuit board 9 is installed and a bottom surface on which the reflection sheet 3 is placed.

As described above, in the planar light unit 21 according to the second embodiment, the sheet support member 24 extends between the pair of support portions 24a erected on the two opposing sides of the reflection sheet 3 and the pair of support portions 24a. Since it is composed of the transparent plate portion 24b that is passed and disposed on the reflection sheet 3 with a space therebetween , high rigidity is obtained and light is transmitted through the transparent plate portion 24b formed of a transparent material. There is almost no light attenuation, and a reduction in luminance can be suppressed.
In addition, it is preferable to set the transparent plate part 24b as thin as possible so that rigidity can be maintained for weight reduction.

  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, although the planar light unit of each of the above embodiments is used for a backlight of a liquid crystal display device, it may be used as another planar light source for other illumination purposes. In addition, when adopting only for illumination, the optical sheet may not be provided.
In each of the above embodiments, the outer peripheral portion of the diffusion sheet and the sheet supporting member are bonded using a double-sided tape, but other bonding or fixing means may be used. For example, it may be bonded with an adhesive or the like.

In addition, although two prism sheets are used, a light unit employing one prism sheet may be used. Further, a plurality of diffusion sheets may be stacked and installed.
Further, a rim seat may be used instead of the front case. This rim sheet is a double-sided tape used for joining a liquid crystal display panel and a backlight unit (planar light unit), and has a light shielding and reflecting function.
Moreover, although the light of the light source is condensed using a collimator lens, the luminance can be improved by devising the shape of this lens and making the directivity asymmetric.

  DESCRIPTION OF SYMBOLS 1,21 ... Planar light unit, 2,22 ... Back case, 3 ... Reflection sheet, 4,24 ... Sheet support member, 4a, 24c ... Light-shielding part, 6A ... 1st prism sheet, 6B ... 2nd prism sheet, DESCRIPTION OF SYMBOLS 7 ... Polarizing sheet, 8 ... Front case, 9 ... Flexible printed circuit board, 10 ... Collimator lens, 24a ... Support part, 24b ... Transparent board part, L ... Light source

Claims (3)

A reflective sheet;
A sheet support member installed on the reflective sheet;
A diffusion sheet installed on the sheet support member;
A plurality of light sources that are arranged side by side on at least one side of the reflection sheet and irradiate light to a space between the reflection sheet and the diffusion sheet or the sheet support member;
The sheet support member is a support frame extending along the outer peripheral portion of the diffusion sheet, and the diffusion sheet is bonded and fixed to the entire outer peripheral portion with a double-sided tape, and is integrally formed with a resin. A planar light unit, characterized in that a space for installing the light source is provided by cutting out a side surface on the light source side . In the planar light unit according to claim 1 ,
The planar light unit, wherein the sheet support member includes a light shielding portion that covers the upper side of the plurality of light sources and shields light from the light sources. In the planar light unit according to claim 1 or 2 ,
The light source is an LED;
A surface having a collimator lens that is installed on the light emitting surface side of the plurality of light sources and extends along the direction in which the light sources are arranged to collect light emitted from the light sources. Light unit.

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