TWI392931B - Light emitting device - Google Patents

Description

Illuminating device

The present invention relates to a light-emitting device, and more particularly to a light-emitting device having better light uniformity.

Today's social multimedia technology is quite developed, and most of them benefit from the advancement of semiconductor components or display devices. As far as the display is concerned, a liquid crystal display having superior characteristics such as high image quality, good space utilization efficiency, low power consumption, and no radiation has gradually become the mainstream of the market. Since the liquid crystal display panel does not have the function of emitting light, a backlight module must be disposed under the liquid crystal display panel to provide a light source so that the liquid crystal display panel can achieve the purpose of display.

In general, the backlight module can be divided into a side backlight module and a direct backlight module. In addition, according to the type of the light source, it can be further divided into a cold cathode fluoresced lamp (CCFL) light source backlight module and a light emitting diode (LED) light source backlight module. The direct-lit backlight module requires a long light-mixing distance to uniformly mix the light because the light directly enters the user's eyes, so that the thickness of the backlight module becomes thicker. The side-type backlight module integrates the light through the light guide plate and then enters the user's eyes, so the side-type backlight module has the advantage of thinner thickness.

In recent years, liquid crystal displays have gradually developed toward large-size trends. The direct-lit backlight module can cut the entire liquid crystal display panel into M*N blocks, and corresponding to each block according to the image content of each block. The backlight brightness is adjusted (ie, local dimming technique) to highlight the contrast ratio of the picture. Therefore, the contrast ratio (CR) exhibited by the liquid crystal display using the direct type backlight module is greater than the contrast exhibited by the liquid crystal display using the side type backlight module.

The present invention provides a light-emitting device having better light-emitting uniformity.

The invention provides a light-emitting device comprising a plurality of light sources, an optical plate, a plurality of recessed structures and at least one light-emitting structure, wherein the optical plate is disposed above the light source, wherein the optical plate has an upper surface and a lower surface. The recessed structure extends from the upper surface of the optical plate toward the inside of the optical plate, and each of the recessed structures is correspondingly disposed above a light source, wherein the side surface of each of the recessed structures has at least two oblique angles. The light-emitting structure is disposed on at least one of an upper surface and a lower surface of the optical plate, wherein light generated by the light source located under each of the concave structures generates total reflection on the side surface of the concave structure and continues in the optical plate at least once. The reflection is not emitted until the light-emitting structure is exposed.

The invention provides a light-emitting device comprising a plurality of light sources, an optical plate, a plurality of recessed structures and at least one light-emitting structure. The optical plate is disposed above the light source, wherein the optical plate has an upper surface and a lower surface. The recessed structure extends from the upper surface of the optical plate to the inner portion of the optical plate, and each recessed structure is correspondingly disposed above a light source, wherein a side surface of each recessed structure has a first segment surface and a second segment surface, and The first segment surface is not in the same plane as the second segment surface or is not on the same surface. The light-emitting structure is disposed on at least one of an upper surface and a lower surface of the optical plate, wherein light generated by the light source located under each of the concave structures generates total reflection on the side surface of the concave structure and continues in the optical plate at least once. The reflection is not emitted until the light-emitting structure is exposed.

The invention provides a light-emitting device comprising a plurality of light sources, an optical plate, a plurality of recessed structures and at least one light-emitting structure. The optical plate is disposed above the light source, wherein the optical plate has an upper surface and a lower surface. The recessed structure extends from the upper surface of the optical plate to the inner portion of the optical plate, and each recessed structure is correspondingly disposed above a light source, wherein a side surface of each recessed structure has a first segment surface and a second segment surface, and A section of the surface has a first angle with the axis of the recessed structure, and the surface of the second section has a second angle with the axis of the recessed structure. The light-emitting structure is disposed on at least one of an upper surface and a lower surface of the optical plate, wherein light generated by the light source located under each of the concave structures generates total reflection on the side surface of the concave structure and continues in the optical plate at least once. The reflection is not emitted until the light-emitting structure is exposed.

Based on the above, the recessed structure in the optical plate of the present invention allows the light emitted by the light source to be totally reflected at least once in the optical plate until the light-emitting structure is exposed to exit the optical plate. Since the light of the light source is emitted from the optical plate after at least one total reflection or multiple total reflections, the light emitted from the optical plate can exhibit a uniform surface light source.

The above described features and advantages of the present invention will be more apparent from the following description.

In the following embodiments, the illuminating device has a plurality of light sources. However, for simplicity of explanation, only a plurality of light sources are illustrated in FIG. 1 , and only one light source is represented as representative in FIGS. 4 to 11 . However, it is not intended to limit the invention.

1 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention. 2A is an enlarged view showing a recess structure of the light-emitting device of FIG. 1. FIG. 2B illustrates a variation of the recessed structure of FIG. 2A. 3A is a schematic view showing a recessed structure of the light emitting device of FIG. 1. FIG. 3B illustrates a variation of the recessed structure of FIG. 3A.

Referring to FIG. 1 and FIG. 2A , the light-emitting device 100 of the embodiment includes a plurality of light sources 110 , an optical plate 120 , a plurality of recess structures 130 , and a plurality of light-emitting structures 140 . The light source 110 is, for example, a light emitting diode, and the optical plate 120 is disposed above the light source 110. In this embodiment, the light source 110 can be directly attached to the optical plate 120 or spaced apart from the optical plate 120 to serve as a heat dissipation space. A plurality of diffusion particles (not shown) are selectively distributed in the optical plate 120 to improve the uniformity of light emission of the light-emitting device 100.

The optical plate 120 has an upper surface 122 and a lower surface 124. The recessed structures 130 are located in the optical plate 120, and each of the recessed structures 130 is disposed above a light source 110. It should be noted that when the light L emitted from the light source 110 is irradiated to the recess structure 130, total reflection is generated and transferred to the side of the optical plate 120. In this way, the recessed structure 130 can diverge the light L around the recessed structure 130 without being concentrated directly above the light source 110, thereby improving the uniformity of light emission of the light emitting device 100. In other words, by designing the optical plate 120 and the recess structure 130 such that the light of the light source 110 is diverged around, the light mixing distance required by the light source 110 can be further reduced.

As described above, the side surface 132 of each recessed structure 130 has at least two oblique angles, and the recessed structure 130 can be a tapered recess (as shown in FIG. 3A) or a V-shaped recess (as shown in FIG. 3B). ). In detail, referring to FIG. 2A, the side surface 132 of each recessed structure 130 has a first segment surface 132a and a second segment surface 132b, and the first segment surface 132a and the second segment surface 132b are not in the same plane. Or not on the same surface.

In other words, the first segment surface 132a and the axis line G of the recess structure 130 have a first angle θ1 (also referred to as a first tilt angle), and the second segment surface 132b and the axis line G of the recess structure 130 have a first Two angles θ2 (also referred to as second tilt angles). In the present embodiment, in the recessed structure 130, the closer to the side surface 132 of the bottom portion B of the recessed structure 130, the smaller the tilt angle. In other words, the first angle θ1 of the first segment surface 132a that is closer to the bottom B of the recess structure 130 is smaller than the second angle θ2 of the second segment surface 132b that is further away from the bottom B of the recess structure 130.

In the present embodiment, the angle of the second included angle θ2 ranges, for example, between 30° and 60°, and the first included angle θ1 is smaller than the second included angle θ2. In addition, when the thickness of the optical plate 120 is T, and the width of the light source 110 (for example, a light-emitting diode wafer) is W, T and W conform to the following formula:

T=B×W×[Tan(θ1)+Tan(θ2)]

Among them, B is between 0.25 and 0.5.

Table 1 lists the light leakage rate of the recess structure 130 in the optical plate 120 at different folding heights D, the first angle θ1 and the second angle θ2. The arrangement of the light leakage rate can control the intensity of the light source directly above the recess structure 130 to match The need for uniformity of the light source for the illumination device 100, wherein the smaller the spacing between the light sources 110, the greater the desired light leakage rate.

Referring to Table 1, it can be seen from Table 1 that the light leakage rate can be adjusted by adjusting the angle between the first angle θ1 and the second angle θ2.

In other embodiments, as shown in FIG. 2B, the side surface 132 of the recess structure 130 may have a first segment surface 132a, a second segment surface 132b and a third segment surface 132c, and the first segment surface 132a and the recess. The axis line G of the structure 130 has a first angle θ1, the second stage surface 132b has a second angle θ2 with the axis G, and the third stage surface 132c has a third angle θ3 with the axis G. The second included angle θ2 is smaller than the third included angle θ3 and larger than the first included angle θ1.

Table 2 lists the light leakage rates of the recessed structures 130 in the optical plate 120 at different corner heights D1, D2 and the first angle θ1, the second angle θ2, and the third angle θ3.

As can be seen from Table 2, the light leakage rate can be adjusted by adjusting the angles of the first angle θ1, the second angle θ2, and the third angle θ3.

In this embodiment, the light-emitting structure 140 is disposed on the lower surface 124 of the optical plate 120, and the light-emitting structure 140 is, for example, a patterned reflective layer. The patterned reflective layer may be disposed in a dot pattern or other optically uniformized. The effect is arranged, and the material of the patterned reflective layer can be a highly reflective material such as ink. The light L generated by the light source 110 located under the recessed structure 130 can be totally reflected by the side surface 132 of the recessed structure 130 and continues to be at least once totally reflected in the optical plate 120 until the light-emitting structure 140 is encountered to exit the optical plate 120. In other words, when the light L is totally reflected in the optical plate 120, when the light-emitting structure 140 is encountered, the total reflection effect is destroyed, so that the light L is emitted from the optical plate 120 to emit light. In this embodiment, the light L can be totally reflected by one or more times in the optical plate 120 until the light-emitting structure 140 is received to emit the optical plate 120. At this time, the light-emitting structure 140 can disperse the light-emitting position of the light L, which is helpful. The light uniformity of the light emitting device 100 is improved. In detail, before the light-emitting structure 140 is encountered, the incident angle (or reflection angle) of the light L generated by the light source 110 in the optical plate 120 is maintained at a total reflection angle θ _F , and after the light-emitting structure 140 is encountered The angle of reflection (or angle of incidence) of the light L in the optical plate 120 changes to destroy the total reflection and cause light to exit the upper surface 122 of the optical plate 120. Further, in the following embodiments of FIGS. 4 to 9, the reflection path of the light in the optical plate 120 is similar to the reflection path of the light L in the optical plate 120 in FIG.

In this embodiment, the light source 110 can be disposed on a substrate 150. In detail, the substrate 150 can be a circuit board, and the substrate 150 has a plurality of grooves 152, each of the grooves 152 can be correspondingly located below a recess structure 130, and the light source 110 can be disposed in the recess 152 and The substrate 150 is electrically connected. In addition, in order to improve the light utilization rate of the light source 110, a reflective layer (not shown) may be formed on the inner wall 152a of the recess 152 to reflect the light that is irradiated to the inner wall 152a. In addition, a transparent colloid 160 may be filled in the recess 152 to cover and protect the light source 110.

In addition, the light-transmitting colloid 160 may be doped with phosphor powder or diffusing particles to adjust the color of the light emitted by the light-emitting device 100 or to improve the light-emitting uniformity of the light-emitting device 100. The transparent colloid 160 and the optical plate 120 may be integrally formed or formed separately, and the material of the transparent colloid 160 may be the same as or different from the material of the optical plate 120. In this embodiment, an optical film 170 can be disposed above the optical plate 120. The optical film 170 is, for example, a brightness enhancement sheet, an anti-reflection sheet, a diffusion sheet, etc., which can improve the brightness or uniformity of the light-emitting device 100. Light film.

4 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention. Referring to FIG. 4 , the structure of the light-emitting device 400 of the present embodiment is similar to that of the light-emitting device 100 of FIG. 1 . The difference between the two is that the light-emitting structure 140 of the light-emitting device 400 is disposed on the upper surface 122 of the optical plate 120 . The light exit structure 140 is, for example, a patterned reflective layer. Similarly, when the light of the light source 110 is totally reflected in the optical plate 120, when the light-emitting structure 140 is encountered, the total reflection effect is destroyed, so that the light L is emitted from the optical plate 120 to emit light. In the present embodiment, to enhance the reflectivity of the lower surface 124 of the optical plate 120, a reflective layer 410 may be disposed on the lower surface 124 of the optical plate 120.

FIG. 5 is a cross-sectional view showing a light emitting device according to another embodiment of the present invention. Referring to FIG. 5 , the structure of the illuminating device 500 of the present embodiment is similar to that of the illuminating device 100 of FIG. 1 . The difference between the two is that the light emitting structure 140 of the illuminating device 500 includes a first patterned reflective layer 142 and a The second patterned reflective layer 144 is disposed, and the first patterned reflective layer 142 and the second patterned reflective layer 144 are respectively disposed on the upper surface 122 and the lower surface 124 of the optical plate 120. The first patterned reflective layer 142 is a plurality of microstructures (for example, semi-circular protrusions), and the first patterned reflective layer 142 can destroy total reflection so that the light L emits light from the optical plate 120 and can emit light. The light source of the panel 120 is concentrated and brightened. The second patterned reflective layer 144 can be a dot structure to facilitate the emission of light L from the upper surface 122 of the optical plate 120.

6A is a cross-sectional view of a light emitting device according to still another embodiment of the present invention, and FIG. 6B is a view showing a variation of the light emitting device of FIG. 6A. Referring to FIG. 6A, the structure of the illuminating device 600 of the present embodiment is similar to that of the illuminating device 100 of FIG. 1. The difference between the two is that the illuminating device 600 further includes an adhesive layer between the optical plate 120 and the substrate 150. 610, and an air gap S exists between the optical plate 120 and the transparent colloid 160. In the present embodiment, when the light is emitted from the surface of the light source 110, since the refractive index of the air in the air gap S is smaller than the refractive index of the transparent colloid 160, at the interface between the transparent colloid 160 and the air gap S, only The light L smaller than the total reflection angle can emit the light-transmitting colloid 160, so that the air gap S can limit the angle at which the light L is incident on the optical plate 120, thereby generating the effect of collecting light. Therefore, the light L incident on the optical plate 120 is more easily irradiated to the recess structure 130 to cause total reflection.

On the contrary, referring to FIG. 6B, if the transparent colloid 160 is directly connected to the optical plate 120 (that is, there is no air gap S), since the refractive index of the transparent colloid 160 is close to the refractive index of the optical plate 120, the surface of the light source 110 is emitted. The light ray L is incident on the optical plate 120 at an angle of the aforementioned total reflection angle, and is directly emitted from the optical plate 120 without being irradiated to the recess structure 130.

FIG. 7 is a cross-sectional view showing a light emitting device according to still another embodiment of the present invention. Referring to FIG. 7, the structure of the light-emitting device 700 of the present embodiment is similar to that of the light-emitting device 100 of FIG. 1. The difference between the two is that the upper surface 122 of the optical plate 120 of the light-emitting device 700 is a non-planar surface. Light exit structure 140. In detail, in the present embodiment, the thickness of the optical plate 120 near the recess structure 130 is greater than the thickness of the optical plate 120 away from the recess structure 130. Since the upper surface 122 of the optical plate 120 is a non-planar (e.g., beveled), the light L of the light source 110 is totally reflected in the optical plate 120, when it encounters the upper surface 122 of the optical plate 120 due to the angle of the bevel When the relationship causes the total reflection to be broken, the light L can be emitted from the optical plate 120 to emit light.

Figure 8 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention. Figure 9 is a diagram showing a variation of the lighting apparatus of Figure 8. Referring to FIG. 8, the structure of the illuminating device 800 of the present embodiment is similar to that of the illuminating device 600 of FIG. 6. The difference between the two is that a concentrating structure 810 is disposed in the optical plate 120 of the illuminating device 800 (for example, The lens) and the concentrating structure 810 are located below the recess structure 130. The concentrating structure 810 can condense the light emitted by the light source 110, and reduce the divergence angle of the light source 110, so that more light can be smoothly reflected in the recess structure 130, and the light of the light source 110 is At least one total reflection continues in the optical plate 120. In this embodiment, the concentrating structure 810 is hemispherical. In other embodiments, the concentrating structure 810 can also be cylindrical (as shown in FIG. 9).

Fig. 10A is a cross-sectional view showing a light-emitting device according to an embodiment of the present invention. FIG. 10B is a partial enlarged view of the optical plate of FIG. 10A.

The structure of the illuminating device 1000 of the present embodiment is similar to the structure of the illuminating device 100 of FIG. 1 . The difference between the two is that the light emitting structure 140 of the illuminating device 1000 is a plurality of microstructures 146 . Moreover, the side surface 126 of the optical plate 120 of the light-emitting device 1000 has an acute angle θ with a horizontal plane A.

In the present embodiment, the light-emitting structure 140 is a plurality of saw-toothed microstructures 146. The apex angle θ4 of the microstructure 146 can be between 30° and 60°, and the height H of the microstructure 146 can be between 50 microns and 200 microns.

The microstructures 146 can be selectively disposed on the lower surface 124, the upper surface 122 of the optical plate 120, or both the lower surface 124 and the upper surface 122 of the optical plate 120. When the microstructures 146 are simultaneously disposed on the lower surface 124 and the upper surface 122 of the optical plate 120, the microstructures 146 on the upper surface 122 and the microstructures 146 on the lower surface 124 are staggered. In other words, the projection of the microstructures 146 on the upper surface 122 on the substrate 150 and the projections of the microstructures 146 on the lower surface 124 on the substrate 150 may not overlap each other or partially overlap each other.

Referring to FIG. 10B, similarly, in the present embodiment, when the light L of the light source 110 is totally reflected in the optical plate 120 and transmitted to the side of the optical plate 120, when the light 120 encounters the light emitting structure 140 or the side At the surface 126, the total reflection effect is destroyed and the light L is emitted from the optical plate 120 to emit light.

In detail, before the light-emitting structure 140 is encountered, the incident angle (or reflection angle) of the light L generated by the light source 110 in the optical plate 120 is maintained at a total reflection angle θ _F , and after the light-emitting structure 140 is encountered The angle of reflection (or angle of incidence) of the light L within the optical plate 120 is reduced to destroy the total reflection and to exit the upper surface 122 of the optical plate 120.

In addition, in the embodiment, the lower surface 124 of the optical plate 120 may further have two slits 124a, 124b, and the slits 124a, 124b are respectively located on opposite sides of the recess structure 130. The slits 124a, 124b can also be used as a light-emitting structure. In detail, after the light L of the light source 110 encounters the concave structure 130 in the optical plate 120 to cause total reflection, the slits 124a, 124b may be encountered to destroy the total reflection effect to emit the upper surface 122 of the optical plate 120 to emit light. .

FIG. 11 is a schematic diagram of a light emitting device according to an embodiment of the invention. Referring to FIG. 11, the structure of the light-emitting device 1100 of the present embodiment is similar to that of the light-emitting device 100 of FIG. 1. The difference between the two is that the light-emitting structure 140 of the light-emitting device 1100 is a plurality of slits 148a located on the lower surface 124. , 148b, 148c, 148d, 148e, and in these slits 148a, 148b, 148c, 148d, 148e, the farther the slit is from the light source 110, the deeper the seam (for example, the slit 148e), and conversely, the closer to the light source 110 The shallower the slit (for example, the slit 148a). Similarly, when the light of the light source 110 is totally reflected in the optical plate 120 and transmitted to the side of the optical plate 120, when the light 120 encounters the slits 148a, 148b, 148c, 148d, 148e, the total reflection is destroyed. Light ray L is emitted from the upper surface 122 of the optical plate 120 to emit light.

In summary, since the optical plate of the present invention is provided with a concave structure, the concave structure can cause the light emitted by the light source to generate total reflection at the concave structure and continue to perform at least one total reflection in the optical plate until the light-emitting structure is encountered. The optical plate is emitted, so that the recessed structure can improve the uniformity of light emission of the light-emitting device. In addition, since the recessed structure of the optical plate is designed to diverge the light of the light source around the recessed structure, the light mixing distance required by the light source can be further reduced. Thus, the distance between the optical plate of the present invention and the light source can be minimized, even directly bonded together. As such, it will contribute to the trend of thinning of the light-emitting device.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100, 400, 500, 600, 700, 800, 1000, 1100. . . Illuminating device

110. . . light source

120. . . Optical board

122. . . Upper surface

124. . . lower surface

124a, 124b. . . Slot

126. . . Side surface

130. . . Sag structure

132. . . Side surface

132a. . . First surface

132b. . . Second surface

132c. . . Third stage surface

140. . . Light structure

142. . . First patterned reflective layer

144. . . Second patterned reflective layer

146. . . microstructure

148a, 148b, 148c, 148d, 148e. . . Slot

150‧‧‧Substrate

152‧‧‧ Groove

152a‧‧‧ inner wall

160‧‧‧Translucent colloid

170‧‧‧Optical diaphragm

410‧‧‧reflective layer

610‧‧‧Adhesive layer

810‧‧‧ Concentrating structure

A‧‧‧ water level

D, D1, D2‧‧‧ turning height

G‧‧‧Axis line

H‧‧‧ Height

L‧‧‧Light

S‧‧‧Air gap

Thickness of T‧‧‧ optical plates

W‧‧‧Light Diode Wafer Width

Θ‧‧‧ angle

Θ1‧‧‧ first angle

Θ2‧‧‧second angle

Θ3‧‧‧ third angle

Θ4‧‧‧ top angle

θ _F ‧‧‧ total reflection angle

1 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention.

2A is an enlarged view showing a recess structure of the light-emitting device of FIG. 1.

FIG. 2B illustrates a variation of the recessed structure of FIG. 2A.

3A is a schematic view showing a recessed structure of the light emitting device of FIG. 1.

FIG. 3B illustrates a variation of the recessed structure of FIG. 3A.

4 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a light emitting device according to another embodiment of the present invention.

6A is a cross-sectional view of a light emitting device according to still another embodiment of the present invention.

Figure 6B illustrates a variation of the illumination device of Figure 6A.

FIG. 7 is a cross-sectional view showing a light emitting device according to still another embodiment of the present invention.

Figure 8 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention.

Figure 9 is a diagram showing a variation of the lighting apparatus of Figure 8.

Fig. 10A is a cross-sectional view showing a light-emitting device according to an embodiment of the present invention.

FIG. 10B is a partial enlarged view of the optical plate of FIG. 10A.

FIG. 11 is a schematic diagram of a light emitting device according to an embodiment of the invention.

100. . . Illuminating device

110. . . light source

120. . . Optical board

122. . . Upper surface

124. . . lower surface

130. . . Sag structure

132. . . Side surface

140. . . Light structure

150. . . Substrate

152. . . Groove

152a. . . Inner wall

160. . . Light-transmitting colloid

170. . . Optical diaphragm

L. . . Light

T. . . Optical plate thickness

W. . . Width of the LED wafer

Claims (33)

A light-emitting device comprising: a plurality of light sources; an optical plate disposed above the light sources, wherein the optical plate has an upper surface and a lower surface, the upper surface being a non-planar surface; and a plurality of recessed structures, The upper surface of the optical plate extends toward the interior of the optical plate, and each recessed structure is correspondingly disposed above a light source, wherein a side surface of each recessed structure has at least two oblique angles, and the portion adjacent to the recessed structures The thickness of the optical plate is greater than the thickness of the optical plate away from the recessed structures such that the upper surface serves as at least a portion of a light exiting structure, wherein light generated by the light source under each recessed structure is in the recessed structure The side surface is totally reflected and continues to undergo at least one total reflection in the optical plate until the light exiting structure is exposed to exit the optical plate. The illuminating device of claim 1, wherein in each of the recessed structures, the inclination angle of the side surface closer to the bottom of the recessed structure is smaller. The light-emitting device of claim 1, wherein the light-emitting structure further comprises a patterned reflective layer disposed on an upper surface of the optical plate. The light-emitting device of claim 1, wherein the light-emitting structure further comprises a patterned reflective layer disposed on a lower surface of the optical plate. The light-emitting device of claim 1, wherein the light-emitting structure further comprises a first patterned reflective layer and a second patterned reflective layer respectively disposed on the upper surface and the lower surface of the optical plate. The illuminating device of claim 1, further comprising a substrate, wherein the light sources are disposed on the substrate, wherein the optical plate and the substrate further comprise an adhesive layer. The illuminating device of claim 6, wherein the optical plate has an air gap between the optical source and the light source. The illuminating device of claim 1, further comprising a plurality of concentrating structures disposed in the optical plate, and each concentrating structure is disposed below a recessed structure. The illuminating device of claim 1, wherein the lower surface of the optical plate further comprises a plurality of microstructures as another part of the light-emitting structure. The illuminating device of claim 1, wherein the upper surface of the optical plate further comprises a plurality of microstructures as another part of the light-emitting structure. The illuminating device of claim 1, wherein the upper surface and the lower surface of the optical plate further comprise a plurality of microstructures as another part of the light-emitting structure, and the microstructures on the upper surface Interlaced with the microstructures located on the lower surface. The illuminating device of claim 1, wherein the side surface of the optical plate has an acute angle with a horizontal plane. The illuminating device of claim 1, further comprising a plurality of diffusing particles distributed in the optical plate. The illuminating device of claim 1, wherein the recessed structures are V-shaped grooves or tapered grooves. The illuminating device of claim 14, further comprising at least one optical film located above the optical plate. A light-emitting device comprising: a plurality of light sources; an optical plate disposed above the light sources, wherein the optical plate has an upper surface and a lower surface, and the lower surface has a plurality of slits as at least one light-emitting structure a plurality of recessed structures extending from the upper surface of the optical plate toward the interior of the optical plate, each recessed structure being correspondingly disposed above a light source, wherein a side surface of each recessed structure has at least two oblique angles, The light generated by the light source under each recessed structure generates total reflection on the side surface of the recessed structure and continues to perform at least one total reflection in the optical plate until the light exiting structure is received. The illuminating device of claim 16, wherein the slits are located on opposite sides of the recessed structure. The illuminating device of claim 16, wherein the slits have different depths. The illuminating device of claim 18, wherein the farther the slit is from the light source, the deeper the seam is, and the closer the slit is, the shallower the depth is. The illuminating device of claim 16, wherein in each of the recessed structures, the inclination angle of the side surface closer to the bottom of the recessed structure is smaller. The illuminating device of claim 16, wherein the illuminating device The light-emitting structure further includes a patterned reflective layer disposed on the upper surface of the optical plate. The light-emitting device of claim 16, wherein the light-emitting structure further comprises a patterned reflective layer disposed on a lower surface of the optical plate. The light-emitting device of claim 16, wherein the light-emitting structure further comprises a first patterned reflective layer and a second patterned reflective layer respectively disposed on the upper surface and the lower surface of the optical plate. The illuminating device of claim 16, further comprising a substrate, wherein the light sources are disposed on the substrate, wherein the optical plate and the substrate further comprise an adhesive layer. The illuminating device of claim 24, wherein the optical plate has an air gap with the light source. The illuminating device of claim 16, further comprising a plurality of concentrating structures disposed in the optical plate, and each concentrating structure is disposed below a recessed structure. The illuminating device of claim 16, wherein the lower surface of the optical plate further comprises a plurality of microstructures as another part of the light-emitting structure. The illuminating device of claim 16, wherein the upper surface of the optical plate further comprises a plurality of microstructures as another part of the light-emitting structure. The illuminating device of claim 16, wherein the upper surface and the lower surface of the optical plate further comprise a plurality of microstructures as Another portion of the light exiting structure, and the microstructures on the upper surface are interleaved with the microstructures on the lower surface. The illuminating device of claim 16, wherein the side surface of the optical plate has an acute angle with a horizontal plane. The illuminating device of claim 16, further comprising a plurality of diffusing particles distributed in the optical plate. The illuminating device of claim 16, wherein the recessed structures are V-shaped grooves or tapered grooves. The illuminating device of claim 32, further comprising at least one optical film located above the optical plate.