US20190187521A1

US20190187521A1 - Backlight module

Info

Publication number: US20190187521A1
Application number: US16/227,016
Authority: US
Inventors: Wei-Chih Chang; I-Min Lu; Kuan-Hsien Jiang
Original assignee: Hon Hai Precision Industry Co Ltd
Current assignee: Hon Hai Precision Industry Co Ltd
Priority date: 2017-12-20
Filing date: 2018-12-20
Publication date: 2019-06-20
Also published as: TWI735826B; US20190187516A1; TW201928473A; CN109946873A; TWI694288B; US20190187520A1; TWI697716B; CN109946875A; US11156871B2; TW201928477A; TW201928476A; CN109946874A

Abstract

A lightweight and thin backlight module for an LCD display includes backlight units. Each backlight unit includes a backplane unit, a first reflecting unit on the backplane unit, and at least three LEDs on the backplane unit extending through the first reflecting unit, and a light guiding unit on the first reflecting unit away from the backplane unit. The light guiding unit is transparent. Each backlight unit further includes a second reflecting unit on a side of the light guiding unit away from the backplane unit. The second reflecting unit includes at least one reflecting region and at least one transmitting region. The reflecting region reflects light; the transmitting region allows light to pass through.

Description

FIELD

The subject matter herein generally relates to a backlight module.

BACKGROUND

A liquid crystal display device needs a backlight module to emit light. As the liquid crystal display devices become thinner, the backlight module must also be thinner and lighter. A conventional direct-type backlight module includes a back plate, a reflection sheet on the back plate, a plurality of LEDs (light emitting diodes) on the reflection sheet, a diffusion sheet, and a brightness enhancement film above the LEDs. Reducing a thickness of the backlight module is usually achieved by reducing a distance (mixing distance) between the back plate and the diffusion sheet. However, the density of the LEDs disposed on the back panel must be increased to ensure a uniform light-emitting effect of the backlight module. Increasing the density of the LEDs increases the energy consumption of the backlight module.
Therefore, there is room for improvement in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present technology will now be described, by way of embodiments only, with reference to the attached figures.

FIG. 1 is a cross-sectional view of a backlight module according to a first embodiment of the present disclosure.

FIG. 2 is a planar view of a second reflecting unit of the backlight unit according to an embodiment of the present disclosure.

FIG. 3A through FIG. 3D are planar views of four second reflecting units of the backlight unit according to other embodiments of the present disclosure.

FIG. 4A through FIG. 4C are planar views illustrating three arrangements of second reflecting units of a second reflecting film of the backlight unit.

FIG. 5 is an exploded view of a first reflecting film, a second reflecting film, and LEDs of the backlight unit.

FIG. 6 is a light intensity distribution diagram of a backlight module using the second reflecting film shown in FIG. 4A.

FIG. 7 is a light intensity distribution diagram of a backlight module using the second reflecting film shown in FIG. 4B.

FIG. 8 is a cross-sectional view of a second reflecting unit of the backlight unit according to a modified embodiment of the present disclosure.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure.
The term “coupled” is defined as coupled, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently coupled or releasably coupled. The term “comprising” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like.
FIG. 1 illustrates a direct-type backlight module 100 of an embodiment. The backlight module 100 includes a plurality of backlight units 10 coupled together. As shown in FIG. 1, each of the backlight units 10 includes a backplane unit 11, a first reflecting unit 12 on the backplane unit 11, a group of LEDs 13 on the backplane unit 11 and extending through the first reflecting unit 12, a light guiding unit 14 on a side of the first reflecting unit 12 away from the backplane unit 11, and a second reflecting unit 20 on a side of the light guiding unit 14 away from the backplane unit 11.
The group of LEDs 13 includes at least two LEDs 13 which emit light of different colors. In the present embodiment, the group of LEDs 13 includes three LEDs 13 which emit blue light, red light, and green light, respectively. In other embodiments, each group of LEDs 13 may include four LEDs which emit blue light, red light, green light, and white light, respectively.
As shown in FIG. 1, the first reflecting unit 12 defines three through holes 121. Each of the LEDs 13 is aligned with one of the through holes 121 and extends through one of the through holes 121, thus light from the LED 13 can enter into the light guiding unit 14. In other embodiments, the first reflecting unit 12 may define one through hole 121. The group of LEDs 13 extends through the through hole 121.
The light guiding unit 14 is located between the first reflecting unit 12 and the second reflecting unit 20, thus the light guiding unit 14 can maintain a certain distance between the first reflecting unit 12 and the second reflecting unit 20. The light guiding unit 14 is made of a transparent light guiding material.
As shown in FIG. 1, the second reflecting unit 20 includes a plurality of transmitting regions 23 and a plurality of reflecting regions 21. Light incident on the reflecting regions 21 is reflected, and light incident on the transmitting region 23 passes through the second reflecting unit 20. The reflecting regions 21 are spaced apart from each other, and the transmitting regions 23 are also spaced apart from each other. One transmitting region 23 is between adjacent two reflecting regions 21 and one reflecting region 21 is between adjacent two transmitting regions 23.
When light is emitted from the LED 13, the transmitting region 23 allows a part of the light to directly pass through the light guiding unit 14 and the second reflecting unit 20. Another part of the light may be reflected multiple times before passing through the transmitting regions 23. For example, the light passing through the light guiding unit 14 can be incident on the reflecting region 21 and reflected by the reflecting region 21, and then can be incident on the first reflecting unit 12 and reflected by the first reflecting unit 12, finally passing through the second reflecting unit 20 by the transmitting region 23.
Referring to FIG. 2, the second reflecting unit 20 is rectangular and includes reflecting regions 21 and transmitting regions 23. The reflecting regions 21 include a first reflecting region 211 having a circular shape at center of the second reflecting unit 20, a second reflecting region 212 having a circular ring shape and surrounding the first reflecting region 211, a third reflecting region 213 having a circular ring shape and surrounding the second reflecting region 212, and a fourth reflecting region 214 having a ring shape and surrounding the third reflecting region 213, and so on, until there is an n^threflecting region 21 having a circular ring shape and surrounding an (n-1)^thof the reflecting regions 21. One of the transmitting regions 23 separates every adjacent two of the reflecting regions 21. One of the reflecting regions 21 separates every adjacent two transmitting regions 23. The reflecting regions 21 and the transmitting regions 23 are alternately arranged in a diametric direction D. In addition, the reflecting regions 21 and the transmitting regions 23 at the edge of the second reflecting unit 20 are incomplete as circular rings, that is, are only a part of a circular ring.
As shown in FIG. 1, each of the backlight units 10 further includes a diffusing unit 15 and a brightness-enhancement unit 17. The diffusing unit 15 is on a side of the second reflecting unit 20 away from the LED 13 and the brightness-enhancement unit 17 is on a side of the diffusing unit 15 away from the second reflecting unit 20.
In the present embodiment, as shown in FIG. 1, the backplane units 11 of the plurality of backlight units 10 are coupled together to form an integrated backplane 110. The backlight units 10 of the backlight module 100 share one backplane 110. The first reflecting units 12 of the plurality of backlight units 10 are coupled together to form an integrated first reflecting film 120. The light guiding units 14 of the plurality of backlight units 10 are coupled together to form an integrated light guiding plate 140. The backlight units 10 of the backlight module 100 share one light guiding plate 140. The backlight units 10 of the backlight module 100 share one first reflecting film 120. The second reflecting units 20 of the plurality of backlight units 10 are coupled together to form an integrated second reflecting film 30. The backlight units 10 of the backlight module 100 share one second reflecting film 30. The diffusing units 15 of the plurality of backlight units 10 are coupled together to form a diffusing film 150. The backlight units 10 of the backlight module 100 share one diffusing film 150. The brightness-enhancement units 17 of the plurality of backlight units 10 are coupled together to form an integrated brightness-enhancement film 170. The backlight units 10 of the backlight module 100 share one brightness-enhancement film 170.
FIG. 3A through FIG. 3D show four different second reflecting units 20 in the backlight module 100.
Referring to FIG. 3A, the second reflecting unit 20 is rectangular and includes transmitting regions 23 and reflecting regions 21. The transmitting regions 23 and reflecting regions 21 are distributed in concentric ellipses. The reflecting regions 21 include a first reflecting region 211 having an elliptical shape in a center of the second reflecting unit 20, and other reflecting regions 21 each have an elliptical ring shape and surround the first reflecting region 211. One elliptical ring transmitting region 23 is between every adjacent two reflecting regions 21, and every adjacent two reflecting regions 21 are spaced apart from each other by the one elliptical ring transmitting region 23. One elliptical ring reflecting region 21 is between every adjacent two transmitting regions 23, and every adjacent two transmitting regions 23 are spaced apart from each other by the one elliptical ring reflecting region 21. In addition, the reflecting region 21 and the transmitting regions 23 at the edge of the second reflecting unit 20 are incomplete elliptical rings, that is, only a part of an elliptical ring.
Referring to FIG. 3B, the second reflecting unit 20 is rectangular and includes transmitting regions 23 and reflecting regions 21. The transmitting regions 23 and reflecting regions 21 are distributed in concentric rectangles. The transmitting regions 23 include a first transmitting regions 231 having a rectangular shape in a center of the second reflecting unit 20. Each of other transmitting regions 23 has a rectangular ring shape and surround the first transmitting regions 231. One rectangular ring reflecting region 21 is between every adjacent two transmitting regions 23, and every adjacent two transmitting regions 23 are spaced apart from each other by the one rectangular ring reflecting region 21. One rectangular ring transmitting region 23 is between every adjacent two reflecting regions 21, and every adjacent two reflecting regions 21 are spaced apart by the one rectangular ring transmitting region 23. In addition, the reflecting region 21 and the transmitting regions 23 at the edge of the second reflecting unit 20 are incomplete rectangular rings, that is, are only a part of a rectangular ring.
Referring to FIG. 3C, the second reflecting unit 20 is rectangular and includes a transmitting region 23 and reflecting regions 21. Each reflecting region 21 is in a shape of a dot, the reflecting regions 21 are spaced apart from each other. The other regions of the second reflecting unit 20 excluding the reflecting regions 21 are the transmitting region 23. The transmitting region 23 surrounds each of the reflecting regions 21. Along a direction from a center towards an edge of the second reflecting unit 20, the sizes of the reflecting regions 21 gradually decrease, and distances between adjacent two reflecting regions 21 gradually increase.
Referring to FIG. 3D, the second reflecting unit 20 is rectangular and includes a main portion 201 and a border portion 202 surrounding the main portion 201. The main portion 201 includes transmitting regions 232 spaced apart from each other and a reflecting region 212. Each transmitting region 232 is in a shape of a dot. The other regions of the main portion 201 excluding the transmitting regions 232 are the reflecting region 212. Along a direction from a center towards an edge of the second reflecting unit 20, the sizes of the transmitting regions 232 of the main portion 201 gradually increase. The border portion 202 includes reflecting regions 215 spaced apart from each other and a transmitting region 235. Each reflecting region 215 is in a shape of a dot. The other regions of the border portion 202 excluding the reflecting regions 215 are the transmitting region 235. Along a direction from a center towards an edge of the second reflecting unit 20, the sizes of the reflecting regions 215 of the border portion 202 gradually decrease.
It can be understood that the reflecting regions 21 and the transmitting regions 23 of the second reflecting unit 20 are not limited to the shapes and layouts described above, and may be in other shapes and layouts.
Referring to FIG. 4B, a rectangular second reflecting film 30 includes second reflecting units 20. Each second reflecting unit 20 has a rectangular shape, and the second reflecting units 20 are arranged in a matrix having rows along a first direction D1 and columns along a second direction D2. The first direction D1 is perpendicular to the second direction D2. The second reflecting units 20 in each row are serially coupled together, and the second reflecting units 20 in each column are serially coupled together.
Referring to FIG. 4A, a second reflecting film 30 includes second reflecting units 20 each having a rectangular shape. The second reflecting units 20 are arranged in rows along a first direction D1. The second reflecting units 20 in each row are serially coupled together. The rows of the second reflecting units 20 are serially coupled together along the second direction D2. The odd-numbered rows 301 of the second reflecting units 20 are aligned with each other in the first direction D1, and the even-numbered rows 302 of the second reflecting units 20 are aligned with each other in the first direction D1. Each odd-numbered row 301 of the second reflecting units 20 is staggered in relation to the even-numbered rows 302 of the second reflecting units 20 in the first direction D1. Each odd-numbered row 301 of the second reflecting units 20 is staggered or offset by a certain distance from the even-numbered row 302 of the second reflecting units 20 in the first direction D1. In the present embodiment, the distance is equal to a half of a length/width of one second reflecting unit 20.
Referring to FIG. 4C, a second reflecting film 30 includes second reflecting units 20. Each second reflecting unit 20 is a regular hexagon except for the units at a border. The second reflecting units 20 are arranged in rows along a first direction D1. The second reflecting units 20 in each row are serially coupled together. The rows of the second reflecting units 20 are serially coupled together along the second direction D2. As described above, the LED 13 of each backlight unit 10 aligns with a center position of the second reflecting unit 20, therefore every adjacent two rows of the LEDs 13 of the backlight units 10 are not aligned in the first direction D1.
In the present embodiment, as shown in FIG. 1, each of the transmitting regions 23 of the second reflecting unit 20 is a hole extending through the second reflecting unit 20, and the reflecting regions 21 of the second reflecting unit 20 are made of reflective material. That is, the second reflecting unit 20 is made by defining through holes in a reflecting film (not shown).
In other embodiments, as shown in FIG. 8, each of the second reflecting units 20 includes a transparent substrate 203 and a reflective material layer 205 formed on a surface of the transparent substrate 203 adjacent to the LED 13. The reflective material layer 205 partially covers the surface of the transparent substrate 203. The reflective material layer 205 forms each of the reflecting regions 21 of the second reflecting unit 20. The portion of the transparent substrate 203 that is not covered by the reflective material layer 205 forms the transmitting regions 23 of the second reflecting unit 20.
Referring to FIG. 5, the first reflecting units 20 form the integrated first reflecting film 120 and the second reflecting units 20 form the integrated second reflecting film 30. The arrangement of the second reflecting units 20 is same as that shown in FIG. 4B. The first reflecting film 120 defines through holes 121 which each extend through the first reflecting film 120. Each group of LEDs 13 is formed on the backplane 110 and passes through the first reflecting film 120 through a corresponding one of the through holes 121.
Light intensity distribution diagrams of a backlight module are shown in FIG. 6, wherein the backlight unit of the backlight module is connected in the manner as shown in FIG. 4A. In FIG. 6, the abscissa represents position in the backlight unit 10, and coordinate 0 represents a center position of the backlight unit. The ordinate represents light intensity. As shown in FIG. 6, the backlight module has a uniform light intensity.
Light intensity distribution diagrams of a backlight module are shown in FIG. 7, wherein the backlight unit of the backlight module is connected in the manner as shown in FIG. 4B. In FIG. 7, the abscissa represents position in the backlight unit 10, and coordinate 0 represents a center position of the backlight unit, the ordinate represents light intensity.
It is to be understood, even though information and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the present embodiments, the disclosure is illustrative only; changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present embodiments to the full extent indicated by the plain meaning of the terms in which the appended claims are expressed.

Claims

What is claimed is:

1. A backlight module, comprising:

a plurality of backlight units, each of the plurality of backlight units comprising:

a backplane unit;

a first reflecting unit on the backplane unit;

at least three light emitting diodes (LEDs) on the backplane unit and extending through the first reflecting unit, the at least three LEDs emitting lights of different colors; and

a light guiding unit on a side of the first reflecting unit away from the backplane unit, the light guiding unit being transparent;

wherein each of the plurality of backlight units further comprises a second reflecting unit on a side of the light guiding unit away from the backplane unit; and

the second reflecting unit comprises at least one reflecting region and at least one transmitting region; the reflecting region is configured to reflect light; the transmitting region is configured to transmit light.

2. The backlight module of claim 1, wherein the at least three LEDs comprises an LED emitting blue light, an LED emitting red light, and an LED emitting green light.

3. The backlight module of claim 1, wherein the at least one reflecting regions comprises at least two reflecting regions; and the at least one transmitting regions comprises at least two transmitting regions; every adjacent two of the reflecting regions are spaced apart from each other by one of the transmitting regions; every adjacent two of the transmitting regions are spaced apart from each other by one of the reflecting regions.

4. The backlight module of claim 1, wherein the at least one reflecting regions comprises a plurality of reflecting regions spaced apart from each other; and the at least one transmitting regions comprises one transmitting region; the one transmitting region surrounds each of the plurality of reflecting regions.

5. The backlight module of claim 4, wherein sizes of the plurality of reflecting regions gradually decrease along a direction from a center towards an edge of the second reflecting unit.

6. The backlight module of claim 1, wherein the second reflecting unit comprises a main portion and a border portion surrounding the main portion; the main portion comprises a plurality of transmitting regions spaced apart from each other and a reflecting region; a region of the main portion excluding the plurality of transmitting regions is the reflecting region; the border portion comprises a plurality of reflecting regions spaced apart from each other and a transmitting region; a region of the border portion excluding the plurality of reflecting regions is the transmitting region.

7. The backlight module of claim 6, wherein sizes of the plurality of transmitting regions of the main portion gradually increase along a direction from a center towards an edge of the second reflecting unit.

8. The backlight module of claim 6, wherein sizes of the plurality of reflecting regions of the border portion gradually decrease along a direction from a center towards an edge of the second reflecting unit.

9. The backlight module of claim 1, wherein the second reflecting units of the plurality of backlight units are arranged in a matrix comprising a plurality of rows along a first direction and a plurality of columns along a second direction; wherein the first direction is perpendicular to the second direction; the second reflecting units in each of the plurality of rows are serially coupled together, and the second reflecting units in each of the plurality of columns are serially coupled together.

10. The backlight module of claim 1, wherein the second reflecting units of the plurality of backlight units are arranged in a plurality of rows along a first direction; the second reflecting units in each of the plurality of rows are serially coupled together; the plurality of rows of the second reflecting units are serially coupled together along a second direction; wherein the first direction is perpendicular to the second direction; odd-numbered rows of the second reflecting units are aligned with each other in the first direction, and even-numbered rows of the second reflecting units are aligned with each other in the first direction; each of the odd-numbered rows of the second reflecting units is staggered in relation to the even-numbered rows of the second reflecting units in the first direction.

11. The backlight module of claim 10, wherein each of the odd-numbered rows of the second reflecting units offsets a distance from each of the even-numbered rows of the second reflecting units in the first direction; the distance is equal to a half of a length or width of the second reflecting unit.

12. The backlight module of claim 1, wherein each of the at least one transmitting region of the second reflecting unit is a hole extending through the second reflecting unit, and the at least one reflecting region of the second reflecting unit are made of reflective material.

13. The backlight module of claim 1, wherein the second reflecting unit comprises a transparent substrate and a reflective material layer formed on a surface of the transparent substrate adjacent to the at least three LEDs; the reflective material layer partially covers the surface of the transparent substrate; the reflective material layer forms each of the at least one reflecting region; portions of the transparent substrate which are not covered by the reflective material layer define each of the at least one transmitting region.

14. The backlight module of claim 1, wherein the first reflecting unit defines at least one through hole, the at least three LEDs extends through the at least one through hole.

15. A backlight module, comprising:

a backplane;

a first reflecting film on the backplane;

a plurality of light emitting diodes (LEDs) on the backplane unit, being spaced apart from each other, and each extending through the first reflecting film, the plurality of LEDs emitting blue light, red light, and green light; and

a light guiding plate on a side of the plurality of LEDs and the first reflecting film away from the backplane, the light guiding plate is transparent;

wherein the backlight module further comprises a second reflecting film on a side of the light guiding plate away from the backplane;

wherein the second reflecting film comprises a plurality of reflecting regions and a plurality of transmitting regions; each of the plurality of reflecting regions is configured to reflect light; each of the plurality of transmitting regions is configured to transmit light.