Backlight module

Abstract

The invention provides a backlight module. The backlight module comprises a circuit board, a plurality of light-emitting elements, an optical element and a reflecting element, the light-emitting elements are arranged on the circuit board. The light-emitting elements are arranged between the optical element and the circuit board. The optical element has a light guide section made of a non-light-diffusing material. The reflecting element is arranged on the circuit board and located between the optical element and the circuit board. The reflective element includes a grid portion. The grid portion separates the plurality of light-emitting elements. The grid part is provided with a plurality of openings, and the plurality of light-emitting elements are respectively arranged in the plurality of openings. A top surface of the grid portion is higher than the light emitting element and is separated from the optical element by an air gap. No other optical element is arranged among the optical element, the reflecting element and the light-emitting element. The backlight module can reduce light crosstalk between adjacent dimming sections by using a reflective element similar to a grating. When the backlight module is applied to the local dimming of the display device, the halo phenomenon near the boundary of the bright and dark areas of the display picture can be improved.

Description

Technical Field

[0001] The invention relates to a backlight module. Background Art

[0002] In order to improve the contrast, brightness and other performance of LCD displays, some LCD displays currently use backlight modules with local dimming functions (Local Dimming) and are equipped with sub-millimeter light-emitting diodes (Mini-LEDs) that can emit high brightness. This type of backlight module has multiple dimming zones. When each dimming zone corresponds to a bright area of ​​the display screen, the brightness of the backlight source of the zone will be increased simultaneously, and when it corresponds to a dark area of ​​the display screen, the brightness of the backlight source of the zone will be reduced or the backlight source will be turned off. However, because the size of the dimming zone is much larger than the pixel size of the display screen, when a bright and dark boundary area appears in the display screen, the high brightness of the dimming zone will cause light leakage in the dark area of ​​the display screen. In addition, the light output of the high-brightness dimming zone will also spread to other adjacent low-brightness dimming zones, causing a halo phenomenon (Halo) to appear on the display screen. Summary of the invention

[0003] The invention is directed to a backlight module, which can reduce light crosstalk between adjacent dimming zones.

[0004] According to an embodiment of the present invention, a backlight module includes a circuit board, a plurality of light-emitting elements, an optical element, at least one optical film and a reflective element. A plurality of light-emitting elements are disposed on the circuit board and electrically connected to the circuit board. A plurality of light-emitting elements are disposed between the optical element and the circuit board. The optical element has a light-guiding portion formed of a non-light-diffusing material. The optical element is disposed between at least one optical film and a plurality of light-emitting elements. The reflective element is disposed on the circuit board and is located between the optical element and the circuit board. The reflective element includes a grid portion. The grid portion separates a plurality of light-emitting elements. The grid portion has a plurality of openings, and a plurality of light-emitting elements are respectively disposed in the plurality of openings. The top surface of the grid portion is higher than the light-emitting element and is separated from the optical element by an air gap. There are no other optical elements between the optical element, the reflective element and the light-emitting element.

[0005] According to an embodiment of the present invention, a backlight module includes a circuit board, a plurality of light-emitting elements, an optical element, at least one optical film and a reflective element. A plurality of light-emitting elements are disposed on the circuit board and electrically connected to the circuit board. A plurality of light-emitting elements are disposed between the optical element and the circuit board. The optical element has a light-guiding portion formed of a light-transmitting material. The optical element is disposed between at least one optical film and the light-emitting element. The reflective element is disposed on the circuit board and is located between the optical element and the circuit board. The reflective element includes a grid portion, which is located between the plurality of light-emitting elements. The top surface of the grid portion is higher than the light-emitting element and is separated from the optical element by an air gap. There are no other optical elements between the optical element, the reflective element and the light-emitting element.

[0006] Based on the above, the backlight module of the embodiment of the present invention can reduce the optical crosstalk between adjacent dimming intervals by using a reflective element similar to a grating. When the backlight module is applied to the local dimming of a display device, the halo phenomenon near the boundary between the bright and dark areas of the display image can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a cross-sectional schematic diagram of a backlight module according to an embodiment of the present invention;

[0008] Figure 2 A schematic diagram of light distribution of a light emitting element of a backlight module according to an embodiment of the present invention;

[0009] Figure 3 is a schematic top view of an optical microstructure and a light-emitting element of a backlight module according to an embodiment of the present invention;

[0010] Figure 4 A three-dimensional and exploded schematic diagram of a light panel and a reflective element of a backlight module according to an embodiment of the present invention;

[0011] Figure 5 It is a partial three-dimensional and enlarged schematic diagram of a reflective element of a backlight module according to an embodiment of the present invention;

[0012] Figure 6 A schematic cross-sectional and side view of a light panel and a reflective element of a backlight module according to an embodiment of the present invention;

[0013] Figure 7 is a cross-sectional schematic diagram of a backlight module according to another embodiment of the present invention;

[0014] Figure 8 is a cross-sectional schematic diagram of a backlight module according to yet another embodiment of the present invention;

[0015] Fig. 9 A schematic diagram of light distribution of a light emitting element of a backlight module according to another embodiment of the present invention;

[0016] Fig.10 A schematic top view of an optical microstructure and a light-emitting element of a backlight module according to another embodiment of the present invention;

[0017] Fig.11 is a cross-sectional schematic diagram of a backlight module according to yet another embodiment of the present invention;

[0018] Fig.12 is a cross-sectional schematic diagram of a backlight module according to an embodiment of the present invention;

[0019] Fig.13 FIG. 4 is a cross-sectional schematic diagram of a backlight module according to another embodiment of the present invention.

[0020] 100: 10, 10A, 10B, 10C, 10D, 10E: backlight module

[0021] 10a: Dimming zone

[0022] 110: Circuit board

[0023] 120, 120B: Light emitting element

[0024] 120-1: first light emitting element

[0025] 120-2: Second light emitting element

[0026] 130: Reflective element

[0027] 132: Grid

[0028] 132-1: Horizontal subsection

[0029] 132-1t, 132-2t: Top surface

[0030] 132-2: Straight subdivision

[0031] 132o: Opening

[0032] 132s: Inner wall

[0033] 132s-1: Inner wall of the first sub

[0034] 132s-2: The inner wall of the second sub

[0035] 132t: Surface

[0036] 134: Outer frame

[0037] 136: Boss

[0038] 136-1: First boss

[0039] 136-2: Second boss

[0040] 140, 140B, 140D, 140E: Optical components

[0041] 140a: light incident surface

[0042] 140a-1: First sub-light incident surface

[0043] 140a-2: Second sub-light incident surface

[0044] 140a-3: The third light-entry surface

[0045] 140b: light emitting surface

[0046] 140b-1: First light-emitting surface

[0047] 140b-2: Second light-emitting surface

[0048] 140b-3: The third light-emitting surface

[0049] 140c-2, 140c-3: sub-slope

[0050] 140d-1, 140d-2, 140d-3: Sub-convex surface

[0051] 141, 141E: first light guide

[0052] 142, 142D, 142E: second light guide

[0053] 143, 143D, 143E: third light guide

[0054] 150, 150B: Optical microstructure

[0055] 151: First optical microstructure

[0056] 152: Second optical microstructure

[0057] 153: The third optical microstructure

[0058] 160: Diffuser

[0059] 170: Optical film

[0060] 180: Diffusion layer

[0061] A: Spacing

[0062] AG: Air Gap

[0063] D151, D152, D153: Dimensions

[0064] g: Gap

[0065] H136: Height

[0066] t: thickness

[0067] t1: first thickness

[0068] t2: second thickness

[0069] t3: third thickness

[0070] WAG, W132t: Width

[0071] x: second direction

[0072] z: first direction

[0073] θ2, θ3: Angle

[0074] α1: first angle

[0075] α2: Second angle DETAILED DESCRIPTION

[0076] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0077] Figure 1 FIG. 1 is a cross-sectional diagram of a backlight module according to an embodiment of the present invention. Figure 1 The backlight module 10 includes a circuit board 110 and a plurality of light-emitting elements 120 disposed on the circuit board 110. The plurality of light-emitting elements 120 are electrically connected to the circuit board 110. The circuit board 110 is used to drive the light-emitting elements 120. The circuit board 110 and the plurality of light-emitting elements 120 may form a light board LP. For example, in the present embodiment, the circuit board 110 may be a printed circuit board (PCB), and the light-emitting element 120 may be a sub-millimeter light-emitting diode (Mini-LED), but the present invention is not limited thereto.

[0078] The backlight module 10 further includes an optical element 140 and at least one optical film 170. A plurality of light emitting elements 120 are disposed between the optical element 140 and the circuit board 110. The optical element 140 is disposed between at least one optical film 170 and the plurality of light emitting elements 120. For example, in this embodiment, the number of the optical films 170 can be selectively 2, and the optical films 170 can selectively include a brightness enhancement film and a diffusion film. However, the present invention is not limited thereto, and in other embodiments, the number and / or type of the optical films 170 can be designed in other ways according to actual needs.

[0079] The optical element 140 has a light guide portion formed of a non-light-diffusing material. In other words, the optical element 140 has a light guide portion formed of a light-transmitting material. In the present embodiment, the optical element 140 is, for example, a light guide plate. The plurality of light-emitting elements 120 include adjacent first light-emitting elements 120-1 and second light-emitting elements 120-2, and the light guide portion of the optical element 140 includes a first light guide portion 141 and a second light guide portion 142, wherein the first light guide portion 141 overlaps the first light-emitting element 120-1 and the second light-emitting element 120-2, and the vertical projection of the second light guide portion 142 on the circuit board 110 falls between the two vertical projections of the first light-emitting element 120-1 and the second light-emitting element 120-2 on the circuit board 110. In the present embodiment, the optical element 140 also includes a third light guide portion 143, which is located between the first light guide portion 141 and the second light guide portion 142. The first direction z points away from the circuit board 110 and is substantially perpendicular to the circuit board 110. The first light guide portion 141 has a first thickness t1 in the first direction z. The second light guide portion 142 has a second thickness t2 in the first direction z. The third light guide portion 143 has a third thickness t3 in the first direction z.

[0080] The optical element 140 has a light incident surface 140a and a light emitting surface 140b. The light emitting surface 140b is disposed opposite to the light incident surface 140a. The light incident surface 140a is located between the light emitting surface 140b and the plurality of light emitting elements 120. The light incident surface 140a includes a first sub-light incident surface 140a-1, a second sub-light incident surface 140a-2, and a third sub-light incident surface 140a-3, and the first sub-light incident surface 140a-1, the second sub-light incident surface 140a-2, and the third sub-light incident surface 140a-3 belong to the first light guiding portion 141, the second light guiding portion 142, and the third light guiding portion 143, respectively. In the present embodiment, the first sub-light incident surface 140a-1, the second sub-light incident surface 140a-2, and the third sub-light incident surface 140a-3 may be substantially coplanar. The light emitting surface 140b of the optical element 140 includes a first sub-light emitting surface 140b-1, a second sub-light emitting surface 140b-2 and a third sub-light emitting surface 140b-3, and the first sub-light emitting surface 140b-1, the second sub-light emitting surface 140b-2 and the third sub-light emitting surface 140b-3 belong to the first light guiding portion 141, the second light guiding portion 142 and the third light guiding portion 143 respectively.

[0081] It is worth noting that the thickness of each light-guiding portion of the optical element 140 is designed accordingly according to the light intensity distribution provided by the light-emitting element 120 on the light-entering surface 140a. At higher light intensity, the thickness of the optical element 140 can be designed to be thicker to reduce the light transmittance. At lower light intensity, the thickness of the optical element 140 can be designed to be thinner to increase the light transmittance. As a result, the overall light uniformity of the backlight module 10 is improved. Figure 1 and Figure 2 Illustrated with examples.

[0082] Figure 2 FIG. 1 is a schematic diagram of the light distribution of the light emitting element of the backlight module according to an embodiment of the present invention. Figure 1 and Figure 2 In this embodiment, the light distribution of the light emitting element 120 can be Gaussian distribution or Lambertian distribution. When the light distribution of the light emitting element 120 is Gaussian distribution or Lambertian distribution, the light emission direction is more concentrated, so on the light incident surface 140a of the optical element 140, the farther away from the top of two adjacent light emitting elements 120, the weaker the received light intensity will be. In detail, in the present embodiment, the first sub-light incident surface 140a-1 is located directly above two adjacent light-emitting elements 120, the second sub-light incident surface 140a-2 is located outside the first sub-light incident surface 140a-1, and the third sub-light incident surface 140a-3 is located between the first sub-light incident surface 140a-1 and the second sub-light incident surface 140a-2. The second sub-light incident surface 140a-2 is farther away from directly above the two adjacent light-emitting elements 120 than the third sub-light incident surface 140a-3. The light intensity on the second sub-light incident surface 140a-2 is less than the light intensity on the first sub-light incident surface 140a-1, and the light intensity on the third sub-light incident surface 140a-3 is between the light intensity on the first sub-light incident surface 140a-1 and the light intensity on the second sub-light incident surface 140a-2. At this time, the thickness t2 of the second light guide portion 142 can be designed to be smaller than the thickness t1 of the first light guide portion 141, and the third thickness t3 of the third light guide portion 143 can be designed to be larger than the second thickness t2 and smaller than the first thickness t1. This is because the light transmitted to the first sub-light incident surface 140a-1, the second sub-light incident surface 140a-2 and the third sub-light incident surface 140a-3 will have high light intensity, low light intensity and medium light intensity, respectively. According to this design, light with high light intensity will have a greater degree of energy loss after passing through the first light guide portion 141 with a thick thickness, light with low light intensity will have a smaller degree of energy loss after passing through the second light guide portion 142 with a thin thickness, and a light beam with medium light intensity will have a medium degree of energy loss after passing through the third light guide portion 143 with a medium thickness. Therefore, the difference in the intensity of light emitted from the first sub-light emitting surface 140b-1, the second sub-light emitting surface 140b-2 and the third sub-light emitting surface 140b-3 through the light guide element 140 can be reduced, thereby improving the light emission uniformity of the backlight module 10.

[0083] For example, in some embodiments, the thickness ratios of the light guide portions are: 40%≤(t2 / t1)≤60%, 70%≤(t3 / t1)≤90%. However, the present invention is not limited thereto, and in other embodiments, the ratio (t2 / t1) of the second thickness t2 of the second light guide portion 142 to the first thickness t1 of the first light guide portion 141 and the ratio (t3 / t1) of the third thickness t3 of the third light guide portion 143 to the first thickness t1 of the first light guide portion 141 can be appropriately designed according to the change of the light distribution of the light emitting element 120.

[0084] Figure 3 FIG. 1 is a top view of an optical microstructure and a light emitting element of a backlight module according to an embodiment of the present invention. Figure 1 The multiple optical microstructures 150 shown are used to schematically represent the arrangement density of the optical microstructures 150 at various locations. Figure 1 The sizes of the optical microstructures 150 shown in the figure are not intended to represent the relative sizes of the optical microstructures 150 at various locations. For the relative sizes of the optical microstructures 150 at various locations, please refer to Figure 3 .

[0085] Please refer to Figure 1 and Figure 3 In some embodiments, the light incident surface 140a of the optical element 140 may have a plurality of optical microstructures 150. The optical microstructures 150 are used to block and reflect the light beams emitted by the light emitting element 120. In some embodiments, the plurality of optical microstructures 150 are, for example, a plurality of micro depressions, and the depression depth of the micro depressions is, for example, at the level of several μm. The micro depressions may be formed on the light incident surface 140a by, for example, a hot rolling process, but the present invention is not limited thereto.

[0086] It is worth mentioning that by adjusting the size of the optical microstructures 150 and / or the density of the arrangement of the optical microstructures 150 at various locations on the light incident surface 140 a , hot spots of light intensity can be effectively eliminated, further improving the light uniformity of the backlight module 10 .

[0087] For example, in some embodiments, the plurality of optical microstructures 150 may include a plurality of first optical microstructures 151, a plurality of second optical microstructures 152, and a plurality of third optical microstructures 153; the first sub-light incident surfaces 140a-1, the second sub-light incident surfaces 140a-2, and the third sub-light incident surfaces 140a-3 of the first light guide portion 141, the second light guide portion 142, and the third light guide portion 143 may respectively have the first optical microstructure 151, the second optical microstructure 152, and the third optical microstructure 153; the second direction x is substantially parallel to the circuit board 110; and the dimension D151 (indicated at Figure 3) is larger than the dimension D152 (indicated at Figure 3 ), the dimension D153 of the third optical microstructure 153 in the second direction x (indicated at Figure 3 ) is larger than the size D152 of the second optical microstructure 152 in the second direction x and smaller than the size D151 of the first optical microstructure 151 in the second direction x. In other words, as the optical microstructure 150 moves away from directly above the light-emitting element 120, the size of the optical microstructure 150 also decreases. Specifically, in some embodiments, the size D152 of the second optical microstructure 152 and the size D153 of the third optical microstructure 153 can be reduced by 1% to 10% of the size D151 of the first optical microstructure 151 compared to the size D151 of the first optical microstructure 151. However, the present invention is not limited to this. In other embodiments, the relative size relationship of the size D151 of the first optical microstructure 151, the size D152 of the second optical microstructure 152 and the size D153 of the third optical microstructure 153 can be appropriately designed according to the change of the light distribution of the visible light-emitting element 120, and the height of the first optical microstructure 151, the second optical microstructure 152 and the third optical microstructure 153 can be changed like the size, or the optical microstructures can only change in height but remain the same in size, all of which can achieve the effect of improving light uniformity.

[0088] In some embodiments, the arrangement density of the plurality of first optical microstructures 151 is greater than the arrangement density of the plurality of second optical microstructures 152, and the arrangement density of the plurality of third optical microstructures 153 is greater than the arrangement density of the plurality of second optical microstructures 152 and less than the arrangement density of the plurality of first optical microstructures 151. That is, in some embodiments, the farther the optical microstructure 150 is from directly above the light-emitting element 120, the wider the spacing A between adjacent optical microstructures 150, or the smaller the size of the optical microstructure. However, the present invention is not limited thereto, and in other embodiments, the size relationship of the arrangement density of the first optical microstructure 151, the arrangement density of the second optical microstructure 152, and the arrangement density of the third optical microstructure 153 can be matched with different optical microstructure height variation differences, and other appropriate designs can be made depending on the change in the light type distribution of the light-emitting element 120.

[0089] Please refer to Figure 1 In some embodiments, the backlight module 10 may further selectively include a diffuser 160 disposed between at least one optical film 170 and the optical element 140. The diffuser 160 can diffuse the light beam from the light emitting surface 140b of the optical element 140, thereby further improving the light emitting uniformity of the backlight module 10.

[0090] Figure 4The figure is a three-dimensional and exploded schematic diagram of a light panel and a reflective element of a backlight module according to an embodiment of the present invention. Figure 5 It is a partial three-dimensional and enlarged schematic diagram of a reflective element of a backlight module according to an embodiment of the present invention. Figure 6 The figure is a cross-sectional and side view schematic diagram of a light panel and a reflective element of a backlight module according to an embodiment of the present invention.

[0091] Please refer to Figure 1 and Figure 4 , the backlight module 10 further includes a reflective element 130. The reflective element 130 is disposed on the circuit board 110 and is located between the optical element 140 and the circuit board 110. There is no other optical element between the optical element 140, the reflective element 130 and the light-emitting element 120. The reflective element 130 includes a grid portion 132 that separates a plurality of light-emitting elements 120 and has a plurality of openings 132o. The plurality of light-emitting elements 120 are respectively disposed in the plurality of openings 132o of the grid portion 132. In some embodiments, the edges of the light-emitting element 120 and the opening 132o of the reflective element 130 may have a gap g (indicated at Figure 1 ). Preferably, the size of the gap g falls within the range of 0.5 mm to 2 mm, but the present invention is not limited thereto.

[0092] The plurality of light emitting elements 120 correspond to the plurality of dimming zones 10a of the backlight module 10. The grid portion 132 of the reflective element 130 functions similarly to a grating, and can suppress the light beams emitted by the light emitting elements 120 from leaking to adjacent dimming zones 10a. Thus, when the backlight module 10 is applied to local dimming of a display device, the halo phenomenon near the boundary of the bright and dark areas of the display screen can be improved.

[0093] In some embodiments, the reflective element 130 may be formed by injection molding of engineering plastics such as propylene carbonate (PC), polyethylene terephthalate (PET), propylene butadiene styrene resin (ABS), etc., but the present invention is not limited thereto.

[0094] Please refer to Figure 1 , Figure 4 , Figure 5 and Figure 6In some embodiments, the reflective element 130 may have a plurality of inner side walls 132s that respectively define a plurality of openings 132o, and the plurality of inner side walls 132s are inclined relative to the circuit board 110. Through the reflection effect of the inner side walls 132s, the light beam emitted by the light-emitting element 120 can be transmitted more concentratedly toward directly above the dimming zone 10a. For example, in the present embodiment, each inner side wall 132s may include a first sub-inner side wall 132s-1 and a second sub-inner side wall 132s-2, the first sub-inner side wall 132s-1 being located between the optical element 140 and the circuit board 110, the second sub-inner side wall 132s-2 being located between the optical element 140 and the first sub-inner side wall 132s-1, and the first sub-inner side wall 132s-1 having a first included angle α1 (indicated at Figure 6 ), the second sub-inner sidewall 132s-2 and the circuit board 110 have a second included angle α2 (indicated at Figure 6 ), and the first angle α1 is greater than the second angle α2. In this embodiment, 135°≤α1<180°, and 90°≤α2≤135°. However, the present invention is not limited thereto, and the size of the first angle α1 and the second angle α2 may be determined by other designs of the light pattern of the light emitting element 120.

[0095] The grid portion 132 of the reflective element 130 has a top surface 132t, which is higher than the light emitting element 120 and is separated from the optical element 140 by an air gap AG. For example, in some embodiments, the reflective element 130 further includes at least one protrusion 136, which is at least disposed on the grid portion 132 and protrudes in a first direction z away from the circuit board 110. In detail, in some embodiments, the reflective element 130 further includes an outer frame portion 134, which surrounds the grid portion 132 and is connected to the grid portion 132, and the at least one protrusion 136 includes a first protrusion 136-1 and a second protrusion 136-2, the first protrusion 136-1 is disposed on the grid portion 132 and protrudes from the grid portion 132 in the first direction z, and the second protrusion 136-2 is disposed on the outer frame portion 134 and protrudes from the outer frame portion 134 in the first direction z.

[0096] In some embodiments, the protrusion 136 is used to abut against the light incident surface 140a of the optical element 140 to maintain the air gap AG (indicated by Figure 1 In some embodiments, the width WAG of the air gap AG in the first direction z is substantially equal to the height H136 (indicated at Figure 6 ).

[0097] Theoretically, when the width WAG of the air gap AG in the first direction z is zero, the grid portion 132 has the best effect in preventing light crosstalk between adjacent dimming zones 10a. However, in practice, when the width WAG of the air gap AG is zero, the grid portion 132 will block the light emitted directly above, seriously affecting the light emission effect of the backlight module 10, causing a grid-like shadow to appear on the display screen. Therefore, it is necessary to maintain an air gap AG of an appropriate width WAG so that the backlight module 10 can improve the light crosstalk problem while taking into account the overall light emission effect. For example, in some embodiments, the width WAG of the air gap AG may fall within the range of 0.2 mm to 1 mm, but the present invention is not limited thereto.

[0098] Please refer to Figure 1 , Figure 4 and Figure 5 In some embodiments, the grid portion 132 of the reflective element 130 has a surface 132t facing the optical element 140. The surface 132t of the grid portion 132 is substantially parallel to the circuit board 110. The surface 132t of the grid portion 132 has a width W132t in the second direction x parallel to the circuit board 110. In detail, the grid portion 132 includes a plurality of transverse sub-portions 132-1 and a plurality of vertical sub-portions 132-2 that intersect each other, and the surface 132t of the grid portion 132 includes a top surface 132-1t of the transverse sub-portion 132-1 and a top surface 132-2t of the vertical sub-portion 132-2. The width W132t of the surface 132t of the grid portion 132 may refer to the width of the top surface 132-1t of one transverse sub-portion 132-1 or the width of the top surface 132-2t of one vertical sub-portion 132-2. In theory, a wider surface 132t will reduce the brightness of the upper area, so the width W132t should be as narrow as possible. However, for the feasibility of actual mass production, the width W132t should be designed within an appropriate range according to the material properties of the reflective element 130. For example, in the present embodiment, the width W132t may fall within the range of 0.2 mm to 1 mm. Preferably, the width W132t may be substantially equal to 0.4 mm. When the width W132t is designed to be around 0.4 mm, the light utilization efficiency of each dimming zone 10a is increased by 8% compared to the case where there is no grid portion 132, and the light leakage of adjacent dimming zones 10a is reduced by 9%.

[0099] In this embodiment, the surface 132t of the grid portion 132 of the reflective element 130 may have a light reflective layer. Through the reflection effect of the light reflective layer, the brightness on the surface 132t of the grid portion 132 can be increased, the light emitting effect of the backlight module 10 can be improved, and the grid-like shadows in the upper display screen area can be avoided. For example, in this embodiment, the light reflective layer may include a high light reflectivity material such as barium sulfate (BaSO4) and titanium oxide (TiO2), but the present invention is not limited thereto.

[0100] It must be noted that the following embodiments use the component numbers and some contents of the previous embodiments, wherein the same number is used to represent the same or similar components, and the description of the same technical contents is omitted. The description of the omitted parts can refer to the previous embodiments, and the following embodiments will not be repeated.

[0101] Figure 7 FIG. 4 is a cross-sectional schematic diagram of a backlight module according to another embodiment of the present invention. Figure 7 The backlight module 10A and Figure 1 The backlight module 10 is similar to the backlight module 10, and the difference between the two is: Figure 7 The optical element 140 of the backlight module 10A has a diffusion layer 180 but does not include Figure 1 The diffusion sheet 160 of the backlight module 10 is provided.

[0102] Please refer to Figure 7 In some embodiments, the optical element 140 has a diffusion layer 180 on the upper portion, which is formed on the first sub-light emitting surface 140b-1, the second sub-light emitting surface 140b-2 and the third sub-light emitting surface 140b-3 having a height difference. The diffusion layer 180 includes a plurality of diffusion particles (not shown) that can reflect or refract the light beam, so as to increase the number of refractions of the light beam inside the optical element 140, thereby extending the transmission range of the light beam inside the optical element 140, thereby achieving good light mixing uniformity. For example, in the present embodiment, the material of the diffusion particles may be polymethylmethacrylate (PMMA), polystyrene (PS) or titanium oxide (TiO2), but the present invention is not limited thereto.

[0103] The diffusion layer 180 may be formed by coating diffusion particle ink and has a thickness t required for forming the backlight module 10A in the first direction z. For example, in some embodiments, the thickness t may fall within a range of 1 μm to 100 μm, but the present invention is not limited thereto. Figure 7 The backlight module 10A adopts a diffusion layer 180 disposed on the light emitting surface 140b, replacing Figure 1 The diffuser 160 of the backlight module 10 is thus Figure 1 The backlight module 10, Figure 7 The backlight module 10A also has the advantage of being thin.

[0104] Figure 8 FIG. 4 is a cross-sectional schematic diagram of a backlight module according to another embodiment of the present invention. Figure 8 The backlight module 10B and Figure 1 The backlight module 10 is similar to the backlight module 10, and the difference between the two is: Figure 8 The light distribution of the light emitting element 120B of the backlight module 10B is Figure 1 The light pattern distribution of the light emitting element 120 of the backlight module 10 is different.

[0105] Fig. 9 FIG. 1 is a schematic diagram of the light distribution of the light emitting element of the backlight module according to another embodiment of the present invention. Figure 8 and Fig. 9 The light type of the light emitting element 120B of the backlight module 10B is a non-Gaussian light type distribution and a non-Lambertian distribution. Due to the different light type distribution of the light emitting element 120B, the thickness distribution position of the optical element 140B of the backlight module 10B is different from that of the light guide element 140 of the aforementioned embodiment. In addition, the relative size and relative arrangement density of the optical microstructure 150B of the backlight module 10B at each location of the light incident surface 140a are also different from those of the aforementioned embodiment.

[0106] Please refer to Figure 8 and Fig. 9 Specifically, in this embodiment, the light distribution of the light emitting element 120B of the backlight module 10B may be a batwing distribution. That is, in this embodiment, the light intensity on the third sub-light incident surface 140a-3 is greater than the light intensity on the first sub-light incident surface 140a-1, and the light intensity on the first sub-light incident surface 140a-1 is greater than the light intensity on the second sub-light incident surface 140a-2. In response to the light intensity distribution provided by the above-mentioned light-emitting element 120B on the first sub-light incident surface 140a-1, the second sub-light incident surface 140a-2 and the third sub-light incident surface 140a-3, in the present embodiment, the third thickness t3 of the third light guide portion 143 having the third sub-light incident surface 140a-3 is greater than the first thickness t1 of the first light guide portion 141 having the first sub-light incident surface 140a-1, and the first thickness t1 of the first light guide portion 141 having the first sub-light incident surface 140a-1 is greater than the second thickness t2 of the second light guide portion 142 having the second sub-light incident surface 140a-2, so that the thickness of the optical element 140B corresponding to the position with higher incident light intensity is thicker and the thickness of the position with lower incident light intensity is thinner, so as to make the light output uniform. For example, in the present embodiment, 70%≤(t1 / t3)≤90%, 40%≤(t2 / t3)≤60%, but the present invention is not limited thereto.

[0107] Fig.10 FIG. 1 is a top view of an optical microstructure and a light emitting element of a backlight module according to another embodiment of the present invention. Figure 8 The multiple optical microstructures 150B shown are used to schematically represent the arrangement density of the optical microstructures 150B at various locations. Figure 8The sizes of the optical microstructures 150B shown in the figure do not represent the relative sizes of the optical microstructures 150B at various locations. For the relative sizes of the optical microstructures 150B at various locations, please refer to Fig.10 .

[0108] Please refer to Figure 8 , Fig. 9 and Fig.10 In response to the light type distribution of the light-emitting element 120B, in the present embodiment, the size D153 of the third optical microstructure 153 disposed on the third sub-light incident surface 140a-3 in the second direction x is larger than the size D151 of the first optical microstructure 151 disposed on the first sub-light incident surface 140a-1 in the second direction x, and the size D151 of the first optical microstructure 151 disposed on the first sub-light incident surface 140a-1 in the second direction x is larger than the size D152 of the second optical microstructure 152 disposed on the second sub-light incident surface 140a-2 in the second direction x. In this embodiment, the arrangement density of the third optical microstructure 153 arranged on the third sub-light incident surface 140a-3 is greater than the arrangement density of the first optical microstructure 151 arranged on the first sub-light incident surface 140a-1, and the arrangement density of the first optical microstructure 151 arranged on the first sub-light incident surface 140a-1 is greater than the arrangement density of the second optical microstructure 152 arranged on the second sub-light incident surface 140a-2.

[0109] Fig.11 FIG. 4 is a cross-sectional schematic diagram of a backlight module according to another embodiment of the present invention. Fig.11 The backlight module 10C and Figure 8 The backlight module 10B is similar to the backlight module 10B, and the difference between the two is: Fig.11 The backlight module 10C includes the diffusion layer 180 but does not include Figure 8 The diffusion sheet 160 of the backlight module 10B.

[0110] Please refer to Fig.11 In this embodiment, the backlight module 10C includes a diffusion layer 180 formed on the first sub-light emitting surface 140b-1, the second sub-light emitting surface 140b-2 and the third sub-light emitting surface 140b-3 having height differences. The diffusion layer 180 can be used to replace Figure 8 The diffusion sheet 160 of the backlight module 10B is formed Fig.11 The backlight module 10C. Fig.11 The backlight module 10C adopts the diffusion layer 180 disposed on the light emitting surface 140b. Therefore, compared with Figure 8 The backlight module 10B, Fig.11 The backlight module 10C also has the advantage of being thin.

[0111] Fig.12FIG. 4 is a cross-sectional schematic diagram of a backlight module according to an embodiment of the present invention. Fig.12 The backlight module 10D and Figure 1 The backlight module 10 is similar to the backlight module 10, and the difference between the two is: Fig.12 The light guide element 140D of the backlight module 10D is Figure 1 The light guide element 140 of the backlight module 10 is different.

[0112] Please refer to Fig.12 In this embodiment, the light guide element 140D may be designed as a special-shaped polygonal light guide plate. In detail, in this embodiment, at least one of the first sub-light emitting surface 140b-1 of the first light guide portion 141, the second sub-light emitting surface 140b-2 of the second light guide portion 142D, and the third sub-light emitting surface 140b-3 of the third light guide portion 143D may include at least one sub-inclined surface 140c-2, 140c-3, wherein at least one sub-inclined surface 140c-2, 140c-3 is inclined relative to the circuit board 110 and has at least one angle θ2, θ3 with the circuit board 110. The light energy distribution on the light emitting surface 140b can be controlled by at least one sub-inclined surface 140c-2, 140c-3 having at least one angle θ2, θ3 with the circuit board 110. In other words, different light energy distribution effects can be achieved by changing the size of at least one angle θ2, θ3.

[0113] For example, in the present embodiment, the second sub-light emitting surface 140b-2 of the second light guide portion 142D may include a sub-inclined surface 140c-2, and the sub-inclined surface 140c-2 and the circuit board 110 are sandwiched at an angle θ2, and the third sub-light emitting surface 140b-3 of the third light guide portion 143D may include a sub-inclined surface 140c-3, and the sub-inclined surface 140c-3 and the circuit board 110 are sandwiched at an angle θ3, and θ3>θ2. However, the present invention is not limited thereto, and in other embodiments, the relative sizes of the inclination degrees of the plurality of sub-inclined surfaces 140c-2 and 140c-3 may be designed differently depending on the light energy distribution effect to be achieved.

[0114] Fig.13 FIG. 4 is a cross-sectional schematic diagram of a backlight module according to another embodiment of the present invention. Fig.13 The backlight module 10E and Figure 1 The backlight module 10 is similar to the backlight module 10, and the difference between the two is: Fig.13 The light guide element 140E of the backlight module 10E and Figure 1 The light guide element 140 of the backlight module 10 is different.

[0115] Please refer to Fig.13In this embodiment, the light guide element 140E may be designed as a light guide plate with a special-shaped sphere as the structure. In detail, in this embodiment, at least one of the first sub-light emitting surface 140b-1 of the first light guide portion 141E, the second sub-light emitting surface 140b-2 of the second light guide portion 142E, and the third sub-light emitting surface 140b-3 of the third light guide portion 143E may include at least one sub-convex surface 140d-1, 140d-2, 140d-3. By changing the curvature radius of the at least one sub-convex surface 140d-1, 140d-2, 140d-3, the light energy distribution on the light emitting surface 140b can be controlled, thereby achieving different light energy distribution effects.

[0116] For example, in the present embodiment, the first sub-light emitting surface 140b-1 of the first light guide portion 141E, the second sub-light emitting surface 140b-2 of the second light guide portion 142E, and the third sub-light emitting surface 140b-3 of the third light guide portion 143E may include a sub-convex surface 140d-1, a sub-convex surface 140d-2, and a sub-convex surface 140d-3, respectively, wherein the radius of curvature of the sub-convex surface 140d-2 may be greater than the radius of curvature of the sub-convex surface 140d-1, and the radius of curvature of the sub-convex surface 140d-3 may be between the radius of curvature of the sub-convex surface 140d-2 and the radius of curvature of the sub-convex surface 140d-1. However, the present invention is not limited thereto, and in other embodiments, the relative sizes of the radii of curvature of the multiple sub-convex surfaces 140d-1, 140d-2, and 140d-3 may be designed differently depending on the light energy distribution effect to be achieved. In addition, in some embodiments, Fig.12 The light guide element 140D and Fig.13 The light guide element 140E may include a diffusion layer 180 , and the backlight module 10D and the backlight module 10E do not include a diffusion sheet 160 , so as to achieve a thin design.

[0117] It must be pointed out here that Figure 1 , Figure 7 , Figure 8 , Fig.11 , Fig.12 and Fig.13 In the figure, the first optical microstructure 151, the second optical microstructure 152 and the third optical microstructure 153 shown only represent the difference in their arrangement density, and are not the specific number and position of the first optical microstructure 151, the second optical microstructure 152 and the third optical microstructure 153 on the first sub-light incident surface 140a-1, the second sub-light incident surface 140a-2 and the third sub-light incident surface 140a-3. As mentioned above, the size, density and structure height of the first optical microstructure 151, the second optical microstructure 152 and the third optical microstructure 153 can be changed to achieve the effect of improving the uniformity of light.

[0118] In summary, a backlight module according to an embodiment of the present invention includes a plurality of light-emitting elements, an optical element and at least one optical film. The optical element is disposed between the at least one optical film and the plurality of light-emitting elements. The optical element includes a first light-guiding portion located above the plurality of light-emitting elements and a second light-guiding portion away from the plurality of light-emitting elements. In particular, the thickness of the first light-guiding portion and the thickness of the second light-guiding portion are designed to have different thicknesses according to the light type distribution of the light-emitting elements, and an optical microstructure is arranged on the light incident surface corresponding to the light type distribution. As a result, the light output uniformity of the backlight module can be improved.

[0119] In addition, compared with the conventional direct-type backlight module, the conventional direct-type backlight module adopts a design of a diffusion plate and a backlight film that requires a height of about 1 cm, while the backlight module of the present invention uses a microstructure optical element to replace the diffusion plate. Under the condition of using the same number of light-emitting elements 120, the optical cavity height of the backlight module of the present invention only needs to be 2.5 cm, and the thickness of the optical film only needs to be 2.5 cm, which can better meet the requirements of thin display devices. In addition, the present invention uses a reflective element similar to a grating to reduce the optical crosstalk between adjacent dimming intervals in the backlight module. When the backlight module is used for local dimming of a display device, the halo phenomenon near the junction of the bright area and the dark area of ​​the display screen can be improved.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These multiple modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A backlight module, characterized in that: include: Circuit boards; A plurality of light emitting elements are disposed on the circuit board and electrically connected to the circuit board; An optical element, wherein the plurality of light-emitting elements are disposed between the optical element and the circuit board, and the optical element has a light-guiding portion, and the light-guiding portion is made of a non-light-diffusing material; at least one optical film, wherein the optical element is disposed between the at least one optical film and the plurality of light-emitting elements; as well as A reflective element is disposed on the circuit board and located between the optical element and the circuit board, wherein the reflective element comprises: A grid portion separating the plurality of light emitting elements, wherein the grid portion has a plurality of openings, and the plurality of light emitting elements are respectively disposed in the plurality of openings, and the grid portion has a top surface higher than the plurality of light emitting elements and an air gap from the optical element; There is no other optical element between the optical element, the reflective element and the plurality of light emitting elements.

2. The backlight module according to claim 1, characterized in that: The top surface has at least one convex column, and the at least one convex column abuts against the optical element.

3. The backlight module according to claim 1, characterized in that: The top surface of the grid portion has a light reflecting layer.

4. The backlight module according to claim 1, characterized in that: The reflective element further comprises: The outer frame part surrounds the grid part and is connected to the grid part. The outer frame part has at least one convex column, and the at least one convex column abuts against the optical element.

5. The backlight module according to claim 1, characterized in that: The reflective element has a plurality of inner side walls respectively defining the plurality of openings, and the plurality of inner side walls are inclined relative to the circuit board.

6. The backlight module according to claim 5, characterized in that: Each of the inner side walls comprises: A first sub-inner sidewall, located between the optical element and the circuit board; and a second sub-inner sidewall, located between the optical element and the first sub-inner sidewall; The first sub-inner side wall and the circuit board have a first angle, the second sub-inner side wall and the circuit board have a second angle, and the first angle is greater than the second angle.

7. The backlight module according to claim 1, characterized in that: The plurality of light emitting elements include a first light emitting element and a second light emitting element that are adjacent to each other, and the light guide portion includes: at least two first light guide portions, wherein the at least two first light guide portions are respectively located on the first light emitting element and the second light emitting element; and A second light guide portion, wherein the second light guide portion is located between the at least two first light guide portions, the at least two first light guide portions have a first thickness in a first direction, the second light guide portion has a second thickness in the first direction, the first direction is substantially perpendicular to the circuit board, and the second thickness is less than the first thickness.

8. The backlight module according to claim 7, characterized in that: The at least two first light guide portions have a first sub-light incident surface, and the first sub-light incident surface has a first optical microstructure; The second light guide portion has a second sub-light incident surface, and the second sub-light incident surface has a second optical microstructure; The size of the first optical microstructure in the second direction is greater than the size of the second optical microstructure in the second direction, and the second direction is substantially parallel to the circuit board.

9. The backlight module according to claim 8, characterized in that: The light guide portion comprises: At least two third light guide portions are respectively located between the at least two first light guide portions and the second light guide portions, wherein the at least two third light guide portions have a third sub-light incident surface, the third sub-light incident surface has a third optical microstructure, and the size of the third optical microstructure in the second direction is greater than the size of the second optical microstructure in the second direction.

10. A backlight module, characterized in that: include: Circuit boards; A plurality of light emitting elements are disposed on the circuit board and electrically connected to the circuit board; An optical element, wherein the plurality of light-emitting elements are disposed between the optical element and the circuit board, and the optical element has a light-guiding portion, and the light-guiding portion is made of a light-transmitting material; at least one optical film, wherein the optical element is disposed between the at least one optical film and the plurality of light-emitting elements; as well as A reflective element is disposed on the circuit board and located between the optical element and the circuit board, wherein the reflective element comprises: a grid portion, located between the plurality of light emitting elements, wherein a top surface of the grid portion is higher than the plurality of light emitting elements and is separated from the optical element by an air gap; There is no other optical element between the optical element, the reflective element and the plurality of light emitting elements.

Images