WO2013094480A1

WO2013094480A1 - Illumination device, ceiling light, backlight, liquid-crystal display, and television receiver

Info

Publication number: WO2013094480A1
Application number: PCT/JP2012/082129
Authority: WO
Inventors: 敬治清水
Original assignee: シャープ株式会社
Priority date: 2011-12-19
Filing date: 2012-12-12
Publication date: 2013-06-27
Also published as: JPWO2013094480A1; JP5713416B2; CN103946623A; CN103946623B

Abstract

This illumination device is provided with the following: an optical member that has a substantially plate-shaped part that receives light via one surface thereof, namely a light-receiving surface, and surface-emits said light from another surface, namely a light-emitting surface; a housing that has a reflective part opposite the aforementioned light-receiving surface; and a substrate on which a plurality of rows of LEDs are formed, wherein each row of LEDs forms a line in a first direction, extending along the aforementioned reflective part, and the plurality of rows are arranged in a second direction that intersects the first direction. The light-emission direction of the LEDs is angled 90° with respect to the main light-emission direction of the illumination device, and the density with which the LEDs are arranged is gradually increased row by row.

Description

Lighting device, ceiling light, backlight, liquid crystal display device, and television receiver

The present invention relates to a lighting device.

In recent years, light emitting diodes (LEDs) are often used as light sources for lighting devices. LEDs have many advantages such as small size, long life, low power consumption due to high luminous efficiency, and no use of mercury compared to fluorescent lamps (cold cathode tubes, etc.) that have been used in the past. .

The lighting device is attached to the ceiling of a living room and used as indoor lighting, or placed on the back of a liquid crystal display device and used as a backlight. However, since the LED is a point light source, a luminance distribution is formed in the light emitted from the light emitting surface of the illumination device, and uneven luminance tends to occur. Therefore, in order to suppress luminance unevenness caused by the fact that the LED is a point light source, a reflecting member is disposed on the surface facing the light emitting surface, and light is emitted in a direction along the light emitting surface and the surface of the reflecting member. Thus, an illumination device in which LEDs are arranged has been proposed.

However, in the illuminating device, since the light irradiation direction of the LED and the light emitting surface of the illuminating device intersect, the light flux density on the light emitting surface changes depending on the distance from the LED. When the luminous flux density changes in this way, the light emitted from the light exit surface is visually recognized as light with uneven brightness.

Here, FIG. 8 shows the in-plane luminance distribution on the light emitting surface of the conventional lighting device and the luminance distribution along the diameter direction of the light emitting surface. In the vicinity of the LED, the light flux density on the light exit surface increases, and as the distance from the LED decreases, the light flux density on the light exit surface decreases. Therefore, as shown in FIG. It is high and the luminance is low at the outer periphery of the lighting device. That is, uneven brightness occurs in the light emitted from the light exit surface.

JP 2009-187843 A

However, in such an illuminating device, it is known that the light flux density on the light exit surface can be made substantially uniform by narrowing the irradiation angle of the light emitted from the LED (that is, approaching parallel light), A method of attaching a collimator lens to an LED has been proposed (see, for example, Patent Document 1).

However, such an illuminating device has a problem that the cost of components increases because a collimator lens is required.

Therefore, an object of the present invention is to provide an illuminating device that can suppress unevenness in luminance on a light exit surface without providing a collimator lens and reduce member costs.

In order to achieve the above object, the lighting device of the present invention has a substantially plate-like plate-like portion, receives light on a light-receiving surface that is one surface of the plate-like portion, and a light-emitting surface that is the other surface. A surface emitting optical member;
A housing having a reflecting portion facing the light receiving surface;
A substrate in which the LEDs are linearly arranged in a first direction that is a direction along the reflecting portion, and the LED array is formed in a plurality of stages in a second direction intersecting the first direction; With
The light emission direction of the LED is inclined from the direction of 90 ° with respect to the light emission main direction of the lighting device,
The arrangement density of the LEDs is gradually increased for each of the plurality of stages.

According to such a configuration, the change in the incident area where the light from the LED is incident on the reflection part or the light receiving surface can be compensated by the change in the arrangement density of the LED, and the uniformity of the light flux density distribution can be improved. Therefore, even if a collimator lens is not provided, luminance unevenness on the light exit surface can be suppressed, and member costs can be reduced.

In the above configuration, the reflection portion diffuses and reflects light,
The light emission direction of the LED is inclined in a direction from the direction that is 90 ° to the light emission main direction of the lighting device toward the reflection portion,
It is good also as a structure which made the arrangement | positioning density of said LED large as the step toward the said light emission main direction.

According to such a configuration, since the light emission direction of the LED is directed to the reflection portion that diffuses and reflects light, the uniformity of the luminance distribution can be improved. In addition, luminance unevenness can be further suppressed by increasing the number of reflections inside the lighting device.

Further, in this configuration, the angle at which the light emitting direction of the LED is tilted may have a half-value angle in the light distribution characteristic of the LED as an upper limit. This is because if the tilt angle exceeds this upper limit, the total amount of light that is directly incident on the reflecting portion in the vicinity of the LED increases, which is undesirable in terms of improving luminance unevenness.

In the above configuration, the light emission direction of the LED is inclined in a direction from the direction that is 90 ° to the light emission main direction of the illumination device toward the light receiving surface.
It is good also as a structure which made the arrangement | positioning density of said LED small as the step toward the said light emission main direction.

According to such a configuration, the light use efficiency can be improved by suppressing the number of reflections inside the lighting device.

Further, in this configuration, the angle at which the light emitting direction of the LED is tilted may have a half-value angle in the light distribution characteristic of the LED as an upper limit. This is because if the tilt angle exceeds this upper limit, the total amount of light directly incident on the light receiving surface in the vicinity of the LED increases, which is undesirable in terms of improving luminance unevenness.

Further, the lighting device having any one of the above structures may be a ceiling light or a backlight. The liquid crystal display device of the present invention includes this backlight. The television receiver of the present invention includes this liquid crystal display device.

According to the present invention, even if no collimator lens is provided, unevenness in luminance on the light exit surface can be suppressed, and member costs can be reduced.

It is a disassembled perspective view of the illuminating device which concerns on 1st Embodiment of this invention. It is a front view of the LED board which concerns on 1st Embodiment of this invention. It is a partial cross section figure of the illuminating device which concerns on 1st Embodiment of this invention. It is a figure which shows the in-plane luminance distribution in the light-projection surface of the illuminating device which concerns on 1st Embodiment of this invention, and the luminance distribution along the diameter direction of the said light-projection surface. It is a partial cross section figure of the illuminating device which concerns on 2nd Embodiment of this invention. It is a front view of the LED board which concerns on 2nd Embodiment of this invention. It is a disassembled perspective view of the liquid crystal display device which concerns on 3rd Embodiment of this invention. It is a figure which shows the in-plane luminance distribution in the light-projection surface of the conventional illuminating device, and the luminance distribution along the diameter direction of the said light-projection surface.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an exploded perspective view of a lighting device according to an embodiment of the present invention. A lighting device A shown in FIG. 1 is a ceiling light attached to a ceiling surface, and an upper portion in the drawing is attached to the ceiling surface.

As shown in FIG. 1, the lighting device A includes a chassis 1, a drive control unit 2, a light emitting unit 3, and a cover 4, which are arranged in this order from the top. The chassis 1 is a casing attached to the ceiling surface, and is a disk-shaped member made of aluminum. A power connector (not shown) that is provided on the ceiling surface and supplies power passes through the central portion of the chassis 1. A highly reflective surface that efficiently reflects the light emitted from the light emitting unit 3 is formed on the surface (lower side surface) opposite to the surface facing the ceiling surface of the chassis 1. This highly reflective surface is preferably composed of a reflective sheet formed of a material with high diffusivity. For example, white foamed PET (polyethylene terephthalate) or barium sulfate can be used as the material having high diffusivity. Note that a highly reflective surface may be formed by applying a paint such as silver on the lower surface of the chassis 1, or the lower surface of the chassis 1 made of aluminum may be mirror-finished to form a highly reflective surface.

The drive control unit 2 includes circuits such as a power supply circuit that supplies power to the light emitting unit 3 and a control circuit that performs lighting control. When the drive control unit 2 is attached to the chassis 1, the insulating sheet 20 for suppressing leakage to the chassis 1, a circuit board 21 on which a power supply circuit, a control circuit, and the like are mounted, and a support unit that supports the circuit board 21 22 and 23 are provided. The drive control unit 2 also includes a circuit that is electrically connected to a power connector (not shown) provided on the ceiling surface and converts the supplied power into power corresponding to the light emitting unit 3.

The light emitting unit 3 is fixed to the chassis 1 with screws, and the drive control unit 2 is fixed to the light emitting unit 3 with screws. In a state where the drive control unit 2 and the light emitting unit 3 are attached to the chassis 1, the cover 4 is attached so as to surround the side of the chassis 1 where the drive control unit 2 and the light emitting unit 3 are attached. The cover 4 is a member formed in a substantially disc shape with a thickness of about 1.5 to 2.5 mm, and is attached to the chassis 1 from below. The cover 4 is fixed by engaging the outer peripheral portion with the chassis 1 and screwing the central portion to the light emitting unit 3.

The cover 4 is formed of milky white PMMA (polymethyl methacrylate), specifically, PMMA added with a diffusing material or a pigment. In addition to PMMA, PC (polycarbonate) resin, PS (polystyrene) resin, or the like may be used as the resin material. As an optical characteristic of the cover 4, it is desirable that the haze value representing the diffusivity is approximately 100%. The ring cover 4 is formed as an optical member whose bottom surface (light emitting surface) emits light when receiving light from the light emitting unit 3 on the top surface (light receiving surface).

The light emitting unit 3 includes an LED angle 31 and an LED substrate 32 on which an LED (not shown in FIG. 1) as a light source is mounted.

The LED angle 31 is formed by cutting and bending a metal plate. The LED angle 31 includes a rectangular flat plate portion 311, a plate-like fixing portion 312 extending from one long side of the flat plate portion 311, and a fixing portion extending from the other long side of the flat plate portion 311 in the same direction as the fixing portion 312. 313. The LED angle 31 is fixed to the chassis 1 and the cover 4 by screwing while the LED substrate 32 is attached to the flat plate portion 311.

Further, as shown in FIG. 1, the four LED angles 31 are integrally formed as a single member in such a manner that the flat portions 311 are connected to be adjacent to each other. This member is manufactured by pressing a metal plate, and is formed into a regular octagonal cylindrical shape by combining two members.

The front view of the LED board 32 is shown in FIG. The LED substrate 32 has an outer edge formed in a substantially rectangular shape, and a plurality of chip-shaped LEDs 320 are mounted thereon. The LED 320 emits light using the power supplied from the drive control unit 2. In the LED substrate 32, the LEDs 320 are linearly arranged in the longitudinal direction (first direction), and the linear arrangement of the LEDs 320 is arranged in three stages in the short direction (second direction). By arranging the LEDs 320 in this way, the length of the LED substrate 32 in the longitudinal direction can be shortened. Thereby, the length of one side of the regular octagon of the LED angle 31 can be shortened, and the non-light emitting portion where the circuit board 21 is disposed can be reduced.

Also, as shown in FIG. 2, the arrangement density of the LEDs 320 in each stage is changed. Specifically, the arrangement density of the LEDs 320 is increased in the upward direction of FIG.

Here, a partial sectional view of the lighting device A is shown in FIG. The upper direction of FIG. 3 is the light emission main direction of the illumination device A. As shown in FIG. 3, with the LED substrate 32 attached to the LED angle 31, the light emission direction of the LED 320 is from a direction that is 90 ° with respect to the light emission main direction of the lighting device A to the highly reflective surface 1 a of the chassis 1. It becomes the direction tilted in the direction to go. This inclination angle is represented by θ in FIG. Further, the arrangement density of the LEDs 320 on the LED substrate 32 is increased toward the main light emission direction of the illumination device A (that is, the upper side in FIG. 2 is set to the upper side in FIG. 3).

The light emitted from the LED 320 is diffusely reflected by the highly reflective surface 1a of the chassis 1 and received by the light receiving surface 4a of the cover 4, and part of the light is diffused and transmitted through the cover 4 and emitted from the light emitting surface 4b to the outside. Is diffusely reflected by the cover 4 and returns to the inside of the illumination device A.

The incident area where light is incident on the highly reflective surface 1a from the LED 320 increases as the stage toward the light emission main direction of the illumination device A (upper stage in FIG. 3) increases the arrangement density of the LEDs 320 toward the main light emission direction. Since it is enlarged, the change of the incident area can be compensated by the arrangement density of the LEDs 320, and the uniformity of the light flux density distribution can be improved. Therefore, uneven brightness of light emitted from the light emitting surface 4b can be suppressed.

Also, since the light emitting surface of the LED 320 faces the highly reflective surface 1a having high diffusibility, the brightness uniformity of the light emitted from the light emitting surface 4b is increased.

FIG. 4 shows an in-plane luminance distribution on the light emitting surface (light emitting surface) of the illumination device A according to an embodiment of the present invention, and a luminance distribution along the diameter direction of the light emitting surface. As shown in FIG. 4, the difference in luminance between the inner peripheral side and the outer peripheral side is smaller than that in the case of the conventional lighting device (FIG. 8), and uneven luminance can be suppressed.

As described above, according to the present embodiment, it is possible to suppress uneven brightness on the light exit surface without providing a collimator lens, and to reduce the member cost.

It should be noted that the angle θ (FIG. 3) for tilting the light emitting direction of the LED 320 is desirably larger than 0 ° and not larger than 60 °. Generally, the light distribution characteristic of an LED is a Lambertian distribution with the front direction being the maximum, and the half-value angle is 60 °. Therefore, when the tilt angle θ exceeds 60 °, the total amount of light directly incident on the highly reflective surface 1a in the vicinity of the LED increases, and there is a problem in improving luminance unevenness.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The present embodiment is the same as the first embodiment described above in the basic configuration shown in FIG. 1, but the configuration of the LED substrate is different.

FIG. 5 shows a partial cross-sectional view of the illumination device A ′ according to the second embodiment. FIG. 6 is a front view of the LED substrate 32 ′ according to the second embodiment. As shown in FIG. 6, in the LED substrate 32 ′, the arrangement density of the LEDs 320 ′ is reduced in the upward direction of FIG. 6.

The upper direction in FIG. 5 is the light emission main direction of the illumination device A ′. As shown in FIG. 5, with the LED board 32 ′ attached to the LED angle 31 ′, the light emission direction of the LED 320 ′ is received by the cover 4 from a direction that is 90 ° with respect to the light emission main direction of the illumination device A ′. The direction is inclined in the direction toward the surface 4a. This inclination angle is represented by φ in FIG. Further, the arrangement density of the LEDs 320 ′ on the LED substrate 32 ′ is made smaller toward the main light emission direction of the illumination device A ′ (that is, the upper side in FIG. 5 is set to the upper side in FIG. 6). .

Light emitted from the LED 320 ′ is directly incident on the light receiving surface 4 a of the cover 4, a part of the light is diffused and transmitted through the cover 4, is emitted to the outside from the light emitting surface 4 b, and part of the light is diffused and reflected by the cover 4 Return to A 'inside.

The incident area where light is incident on the light receiving surface 4a from the LED 320 'increases in the step opposite to the main light emission direction of the illumination device A' (lower step in FIG. 5), but the direction opposite to the main light emission direction Since the arrangement density of the LEDs 320 ′ is increased toward the step toward, the change in the incident area can be supplemented by the arrangement density of the LEDs 320 ′, and the uniformity of the light flux density distribution can be improved. Therefore, uneven brightness of light emitted from the light emitting surface 4b can be suppressed.

Also, since the light emitting surface of the LED 320 ′ faces the cover 4 having high diffusibility, the brightness uniformity of the light emitted from the light emitting surface 4 b is increased.

In the first embodiment, the number of times of reflection of light inside the lighting device is excellent, so that the effect of suppressing luminance unevenness is excellent. In the second embodiment, the number of times of reflection of light inside the lighting device is reduced. Therefore, it is excellent in terms of light utilization efficiency.

It should be noted that the angle φ (FIG. 5) for tilting the light emitting direction of the LED 320 ′ is desirably larger than 0 ° and not larger than 60 °. As described above, generally, the light distribution characteristic of the LED has a Lambertian distribution with the front direction being maximized, and the half-value angle is 60 °. Therefore, when the tilting angle φ exceeds 60 °, the total amount of light directly incident on the light receiving surface 4a in the vicinity of the LED increases, and there is a problem in improving luminance unevenness.

(Third embodiment)
Since the illuminating device of the present invention emits planar light from the light emitting surface, it can also be used as a backlight of a liquid crystal display device.

Hereinafter, an example in which the lighting device of the present invention is used as a backlight of a liquid crystal display device will be described with reference to the drawings. FIG. 7 is an exploded perspective view showing a liquid crystal display device according to an embodiment of the present invention.

As shown in FIG. 7, the liquid crystal display device 8 includes a liquid crystal panel unit 81, a backlight unit 82, and a bezel 83. A liquid crystal panel unit 81 is disposed on the front side (observer side) of the backlight unit 82, and the liquid crystal panel unit 81 is pressed by a metal bezel 83 having an opening window 830 in the center on the front side.

The liquid crystal panel unit 81 includes a liquid crystal panel 811 in which liquid crystal is sealed, and a polarizing plate 812 attached to the front surface (observer side) and the back surface (backlight unit 82 side) of the liquid crystal panel 811. The liquid crystal panel 811 includes an array substrate 813, a counter substrate 814 arranged to face the array substrate 813, and liquid crystal filled between the array substrate 813 and the counter substrate 814.

The array substrate 813 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 814 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.

In the liquid crystal panel unit 81, a voltage is applied between the array substrate 813 and the counter substrate 814 in each pixel of the liquid crystal panel 811 by driving the switching element. When the voltage between the array substrate 813 and the counter substrate 814 changes, the liquid crystal in each pixel rotates and light is modulated (the degree of light transmission is changed). As a result, an image is displayed in the image display area on the viewer side of the liquid crystal panel 811.

The bezel 83 is a metal frame, and has a shape that covers the front edge portion of the liquid crystal panel unit 81. The bezel 83 includes a rectangular opening window 830 formed so as not to hide the image display area of the liquid crystal panel unit 81, a pressing portion 831 that presses the liquid crystal panel unit 81 from the front side, and a rear surface from the edge of the pressing portion 831. And a cover portion 832 that covers the edges of the liquid crystal panel unit 81 and the backlight unit 82. The bezel 83 is grounded and shields the liquid crystal panel unit 81 and the backlight unit 82.

The backlight unit 82 is an illumination device that irradiates the liquid crystal panel unit 81 with planar light. The backlight unit 82 has a structure equivalent to that of the lighting device described in the first embodiment. That is, it has a backlight chassis 821 having a rectangular bottom surface 821 a corresponding to the chassis 1, a light source unit 822 corresponding to the light emitting unit 3, and an optical member 823. A high reflection surface corresponding to the high reflection surface 1a of the first embodiment is formed on the bottom surface 821a. Further, an optical member 823 that diffuses and transmits and reflects light corresponding to the cover 4 of the first embodiment is disposed on the light emitting surface side of the backlight unit 82.

The light source unit 822 includes an LED angle 31 and an LED substrate 32 on which the LED 320 is mounted. The LED angle 31 is disposed on one short side inside the backlight chassis 821. As in the first embodiment, with the LED board 32 attached to the LED angle 31, the light emission direction of the LED 320 is 90 ° with respect to the main light emission direction of the backlight unit 82 (upward direction in FIG. 7). The direction is inclined from the direction toward the bottom surface 821a. Further, the arrangement density of the LEDs 320 on the LED substrate 32 is increased as it goes toward the light emission main direction (as shown in the upper direction in FIG. 7).

Such a backlight unit 82 can emit planar light with less luminance unevenness than the light emitting surface facing the bottom surface without using a light guide plate, and the number of constituent members can be reduced accordingly.

Note that, as a modification of the present embodiment, an embodiment corresponding to the second embodiment described above may be employed (that is, the method of tilting the LED substrate is changed from the present embodiment).

Further, the liquid crystal display device according to the present invention can be employed in, for example, a mobile phone, a tablet PC, a display device for household electric appliances, a television receiver, and the like.

In each of the embodiments described above, a ceiling light or a backlight unit of a liquid crystal display device is given as the lighting device, but in addition to these, it can also be used as a back-type lighting device that illuminates from the back of an electric signboard or the like. Is also possible.

Although one embodiment of the present invention has been described above, the embodiment can be variously modified within the scope of the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Chassis 1a High reflective surface 2 Drive control part 20 Insulation sheet 21 Circuit board 22 Support part 23 Support part 3 Light emission part 31 LED angle 311 Flat plate part 312 Fixing part 313 Fixing part 32 LED board 320 LED
4 Cover 4a Light-receiving surface 4b Light-emitting surface A Illumination device

Claims

An optical member having a substantially plate-like plate-like portion, receiving light on a light-receiving surface that is one surface of the plate-like portion, and a light-emitting surface that is the other surface emitting light;
A housing having a reflecting portion facing the light receiving surface;
A substrate in which the LEDs are linearly arranged in a first direction that is a direction along the reflecting portion, and the LED array is formed in a plurality of stages in a second direction intersecting the first direction; With
The light emission direction of the LED is inclined from the direction of 90 ° with respect to the light emission main direction of the lighting device,
An illumination device, wherein the arrangement density of the LEDs is gradually increased for each of the plurality of stages.
The reflection unit diffusely reflects light,
The light emission direction of the LED is inclined in a direction from the direction that is 90 ° to the light emission main direction of the lighting device toward the reflection portion,
The lighting device according to claim 1, wherein an arrangement density of the LEDs is increased toward a step toward the light emission main direction.
The lighting device according to claim 2, wherein the angle of inclination of the light emitting direction of the LED has an upper limit of a half-value angle in the light distribution characteristic of the LED.
The light emitting direction of the LED is inclined in a direction from the direction that is 90 ° to the light emitting main direction of the lighting device toward the light receiving surface,
The lighting device according to claim 1, wherein an arrangement density of the LEDs is reduced as a step toward the light emission main direction.
The lighting device according to claim 4, wherein the angle of inclination of the light emission direction of the LED has an upper limit of a half-value angle in the light distribution characteristic of the LED.
The lighting device according to any one of claims 1 to 5, wherein the lighting device is a ceiling light.
6. The lighting device according to claim 1, wherein the lighting device is a backlight.
A liquid crystal display device comprising the backlight according to claim 7.
A television receiver comprising the liquid crystal display device according to claim 8.