TW201621217A - Edge type backlight module and its light guide plate - Google Patents

Abstract

An edge type backlight module and its light guide plate are provided. The light guide plate includes a light transmissive plate, a first microstructure pattern and a plurality of the second microstructure patterns. The light transmissive plate includes a light-incident side surface, a surface light source area containing the first microstructure pattern, and a transition area located between the surface light source area and the light-incident side surface. The second microstructure patterns are disposed in the transition area, and each of the second microstructure patterns is in projectile-shape. The second microstructure patterns are staggered with a plurality of point light sources which are separately arranged at the light-incident side surface of the light transmissive plate. Therefore, when the point light sources emit, every second microstructure pattern becomes a pseudo light source formed between any two neighboring point light sources for diffusing hot spot effect existed on the transition area.

Description

Side-entry backlight module and its light guide plate

The invention relates to a light guide plate, and in particular to a light guide plate of a side-entry backlight module.

With the demand and limitations of modern trends, many illuminating products are developing toward a short, light and thin shape, so that the backlight module in the illuminating product is gradually thinned to reduce the thickness of the light guide plate. The light guide plate of the backlight module includes a light emitting surface, a reflecting surface parallel to the light emitting surface, and a plurality of light incident sides perpendicular to the light emitting surface. The light source of the backlight module includes a plurality of light emitting diodes. The light-emitting diodes are arranged at intervals on one of the light-incident surfaces, and the light of the light-emitting diode enters the light guide plate from the light-incident surface and is guided by the light guide plate, and is evenly distributed on the light-emitting surface to become a surface light source of the backlight module. .

However, since the spaced-apart light-emitting diodes have a predetermined light divergence angle and a gap exists between adjacent light-emitting diodes, when the light-emitting diode emits light into the light guide plate, the light guide plate emits light. The optical spots and dark areas of the surface of the backlight module are poorly formed, and the optical spots and dark areas of the surface of the backlight module are adjacent to each other, and the corresponding positions of the respective light-emitting diodes and the respective gaps are easily generated. Overall light utilization efficiency The reduction in uniformity.

A common solution is to provide a light-shielding frame at a corresponding position of the light-emitting product, so that the light-shielding frame blocks these optical bright spots and dark areas. However, the light-shielding frame cannot completely obscure these optical bright spots and dark areas, and consumers may still see these optical bright spots and dark areas from the side of the light-shielding frame when the light-emitting product is slightly tilted.

It can be seen that the above light guide plate still has inconvenience and defects, and needs to be further improved. Therefore, how to effectively solve the above inconveniences and defects is one of the current important research and development topics, and it has become an urgent need for improvement in related fields.

In view of the above, it is an object of the present invention to provide a side-lit backlight module and a light guide plate thereof to solve the difficulties mentioned in the prior art.

In order to achieve the above object, according to an embodiment of the present invention, the light guide plate receives a plurality of spaced point light sources on a light incident side surface, thereby forming a one-side input backlight module. The light guide plate includes a light transmissive plate body, a first microstructure pattern and a plurality of second microstructure patterns. The light transmissive plate body includes a light source region and a transition region. The transition region is elongated and located between the surface light source region and the light incident side. The first microstructure pattern is distributed in the area of the surface light source. The second microstructure pattern is in the shape of a bullet which cuts an ellipse along the short axis, and is located in the transition region, and is arranged alternately with the spaced point sources. Thus, when these spaced point sources are illuminated, these second microstructures The pattern forms a pseudo-light source between any two point sources, thereby diluting the optical bright spots and dark areas.

According to an embodiment of the invention, the light guide plate comprises a light transmissive plate body, a first microstructure pattern and a plurality of second microstructure patterns. The light-transmitting plate body comprises a light-incident side surface and a light-emitting surface adjacent to the light-incident side surface, and the light-emitting surface is divided into a light source area and a surrounding area surrounding the surface light source area. The first microstructure pattern is distributed in the area of the surface light source. These second microstructure patterns are located in the surrounding area and are linearly arranged along the light incident side. Each of the second microstructured pattern is formed by an ellipse along its short axis. The shell shape has a straight line and an arc, and the two ends of the arc are respectively connected to the two ends of the straight line to form two opposite ends respectively. The intersection point, one of the arcs, is closer to the first microstructure pattern than the intersection of the ends, and the length of the line is equal to the length of the minor axis of the ellipse.

In one or more embodiments of the present invention, each point source has an envelope of 50% light intensity, and the envelopes of any two adjacent point sources have an optical intersection point, and the light intersection point is The convex apex of the cannonball shape.

In one or more embodiments of the present invention, each point source has an envelope of 50% light intensity, and the envelopes of any two adjacent point sources have a light intersection point, and the light intersection point passes through the ellipse A focus where the focus is inside the cannonball shape.

In one or more embodiments of the invention, one of the surrounding areas has a width equal to one-half the length of one of the major axes of the ellipse.

According to an embodiment of the invention, the edge-lit backlight module comprises a light source and the light guide plate. The light source includes a substrate and a plurality of point light sources. The point light sources are linearly arranged on the substrate and spaced apart from each other to the light incident side. A spacing area is defined between any two adjacent point sources, and each of the second microstructure patterns is aligned with one of the spacing areas.

In this way, although the point light source generates the optical bright spots and the dark areas arranged at intervals along the transition surface of the light-emitting surface along the light-incident side, the second microstructure pattern of the above-mentioned bullet-shaped shapes may correspond to any two optical bright points on the transition region. A pseudo-light source is provided to homogenize the brightness of the transition region, thereby diluting the apparent contrast between the optical bright spot and the dark region.

10, 11‧‧‧ Side-in backlight module

100‧‧‧Light guide plate

110‧‧‧Translucent plate

111‧‧‧Glossy surface

112‧‧‧light side

120‧‧‧First microstructured pattern

130‧‧‧Second microstructure pattern

131‧‧‧Optical microstructure

132‧‧‧ Straight line

132d‧‧‧The length of the line

133‧‧‧Arc

133p‧‧‧ convex arc apex

133e‧‧‧End point

140‧‧‧ ellipse

141‧‧‧ short axis

142‧‧‧ long axis

143‧‧ ‧ focus

150‧‧‧Second microstructure pattern

151‧‧‧ diagonal of the triangle

152‧‧‧Bottom of the triangle

160‧‧‧Second microstructure pattern

161‧‧‧ diagonally opposite triangle

162‧‧‧ bottom edge of inverted triangle

170‧‧‧Second microstructure pattern

171, 172‧‧ ‧ square two opposite sides

200‧‧‧Light source

210‧‧‧Substrate

220‧‧‧ point light source

221‧‧‧ side

222‧‧‧ envelope

223‧‧‧Light intersection

224‧‧‧ interval area

AA‧‧‧ surface light source area

M‧‧‧ partial

N‧‧‧ Surrounding Area

T‧‧‧ transitional area

The width of the transition zone of Td‧‧

1 is a top view of a side-lit backlight module according to an embodiment of the present invention; FIG. 2A is a partial enlarged view of a portion M of FIG. 1; FIG. 2B is a schematic view showing an outline of an ellipse; 3 is a partial enlarged view of a side-entry backlight module according to another embodiment of the present invention, the cross-sectional position of which is the same as the portion M of FIG. 1; and FIGS. 4A-4C illustrate other comparative examples according to the present invention. A partially enlarged view, the cross-sectional position of which is the same as the partial M of Fig. 1.

In the following, a plurality of embodiments of the present invention will be disclosed in the drawings. For the sake of clarity, many practical details will be described in the following description. Bright. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not necessary. In addition, some of the conventional structures and elements are shown in the drawings in a simplified schematic manner in order to simplify the drawings.

FIG. 1 is a top view of a side-lit backlight module 10 according to an embodiment of the invention. FIG. 2A is a partial enlarged view of a portion M of FIG. 1 . As shown in FIG. 1 and FIG. 2A , the side-lit backlight module 10 includes a light guide plate 100 and a light source 200 . The light guide plate 100 includes a light transmissive plate body 110, a first microstructure pattern 120 and a plurality of second microstructure patterns 130. The translucent plate body 110 has a substantially plate shape, and the translucent plate body 110 includes at least one light emitting surface 111 and a plurality of light incident side surfaces 112. The light incident sides 112 collectively surround the light exit surface 111 and respectively adjoin the side edges of the light exit surface 111. The first microstructure pattern 120 is located on the light exit surface 111, and defines a light source area AA on the light exit surface 111. The remaining area of the light-emitting surface 111 that does not have the first microstructure pattern 120 is defined as a surrounding area N. The surrounding area N surrounds the surface light source area AA, and there is no first microstructure pattern 120 in the surrounding area N. A narrow region between the surface light source region AA and one of the light incident side surfaces 112 is referred to as a transition region T. The second microstructure pattern 130 is in the shape of a bullet, and is located in the transition region T. The shape of the bullet is formed by an ellipse 140 (ie, an ellipse defined by mathematics, refer to FIG. 2B) along a short axis 141 thereof, and is also called a semi-ellipse. shape.

Of course, the above embodiments are merely illustrative. Since the light guide plate 100 is assembled, there is usually an outer frame around the periphery thereof, so that the outer frame overlaps with the four edges of the light guide plate 100 as the surrounding area N. However, in the practical operation, in the case of the side-in backlight module architecture, since the light bar composed of multiple point light sources is used to simulate the line source of the conventional cold cathode tube, the transition region T has its necessity. But the other three sides do not have to exist. From this, the first microstructure pattern 120 can cover all areas on the upper or lower surface of the light-transmitting plate body 110 except the transition region T.

The light source 200 includes a substrate 210 and a plurality of point light sources 220. The point light source 220 is, for example, a light emitting diode, linearly arranged on the substrate 210, and the point light source 220 is spaced apart from the light incident side surface 112 of the light transmissive plate body 110 closest to the transition region T, and is interlaced with the second microstructure pattern 130. Settings. In other words, a spacer region 224 is defined between any two adjacent point sources 220, and each of the second microstructure patterns 130 is aligned with one of the spacer regions 224 in the transition region T.

In this manner, when the spaced-apart point light sources 220 emit light to the light incident side surface 112 to generate an optical spot corresponding to the point light source 220 in the transition region T, the second microstructure patterns 130 of the above-mentioned bullet-shaped shapes can be transitioned. A pseudo-light source is formed on the region T corresponding to a position between any two optical spots, so that the optical bright spots are mixed with the pseudo-light sources, thereby homogenizing the brightness of the transition region T, thereby diluting the optical bright spots and the dark regions. Obvious contrast.

More specifically, the contour of each of the shell-shaped (semi-elliptical) second microstructure patterns 130 is composed of a straight line 132 and an arc 133. This straight line 132 is the short axis 141 of the ellipse 140, close to, even aligned with, the light exiting surface 111 abutting the side edge of the light side 112. The arc 133 is, for example, C-shaped or U-shaped, and the two ends of the arc 133 are respectively connected to the two ends of the straight line 132 to respectively Two opposite end intersections 133e are formed. The convex arc vertex 133p of the arc 133 is closer to the first microstructure pattern 120 than the two end intersections 133e. It should be emphasized that the shape of the shell shape is defined by the fact that the line of the arc has no turning point and a smooth continuous curve. The specific shape can be controlled by adjusting the three parameters of the semi-elliptical long axis, short axis and focal length.

In other parts of the embodiment, the width Td of the transition region T is greater than the length 132d of the straight line 132 of the second microstructure pattern 130, that is, the shortest distance of the transition region T from the light incident side 112 to the surface light source region AA. The length 132d of the straight line 132 larger than the second microstructure pattern 130 is such that the second microstructure pattern 130 of each of the aforementioned bullet shapes exhibits a semi-elliptical shape in which an ellipse is split in half along the short axis. Of course, this is not a limitation of the invention.

In other parts of the embodiment, the length 132d of the line 132 is equal to the distance between any two adjacent point sources 220. In other words, any two adjacent point sources 220, ie, LEDs, respectively There are mutually facing side faces 221, and these side faces 221 are respectively aligned with the above-mentioned bullet-shaped (semi-elliptical) end intersections 133e. However, the present invention is not limited thereto. In other embodiments, those having ordinary knowledge in the technical field of the present invention may also change the length of the straight line to be smaller than the distance between any two adjacent point light sources, depending on actual needs.

In some embodiments of the present invention, each of the second microstructure patterns 130 is composed of a plurality of optical microstructures 131 that are spaced apart. For example, in the case of a 32-inch to 49-inch, 2 mm thick light guide plate design, a dot with a depth of 30 μm and a radius of 50 μm The optical microstructures 131 and the second microstructures 130 may have a distribution density of 30 to 70%, which is the total area of the plurality of optical microstructures 131 and the second microstructure pattern 130. The area ratio; this is because if the brightness of the point source 220 is strong, when the pseudo-light source is simulated by the second microstructure pattern 130, a denser or deeper optical microstructure 131 is required; and vice versa. It is verified by actual production that it can make the optical uniformity of the transition region T more than 75%. However, the present invention is not limited thereto, and in other embodiments, those having ordinary knowledge in the technical field to which the present invention pertains may also change the set distribution density to other ranges as needed.

In some embodiments, the contour design parameters of the bullet-shaped pseudo-light source can be further estimated by the following conditions: the envelope 222 of the 50% light intensity of each point light source 220 is used as a reference. The envelopes 222 of the adjacent point sources 220 share a light intersection 223, which can be defined as the convex arc apex 133p of the corresponding bullet-shaped (semi-elliptical) pseudo-source. In the actual design case of the 32 吋 and 49 导 light guide plates, the point light source 220 is based on the envelope 222 of 50% light intensity; of course, the invention is not limited thereto, and other embodiments may also use a point light source. The envelope of other light intensities, such as 40% or 60% of the light intensity, is the basis for designing the range of the second microstructure pattern 130.

In the actual design case of the 32 吋 and 49 导 light guide plates described above, the width Td of the transition region T is equal to one-half the length of the long axis 142 of the ellipse 140; that is, the transition region T is from the light incident side 112 to the surface light source region AA. The shortest distance is equal to the shortest distance from the convex arc vertex 133p of the arc 133 to the straight line 132. However, the present invention is not limited thereto, and in other embodiments, the present invention The person having ordinary knowledge in the technical field of the present invention may also change the width of the transition region to be larger than one half of the length of the long axis of the ellipse according to actual needs.

FIG. 3 is a partial enlarged view of the side-entry backlight module 11 according to another embodiment of the present invention, and the cross-sectional position thereof is the same as the portion M of FIG. 1 . As shown in Fig. 3, the structure of the light guide plate of the present embodiment is substantially the same as the structure of the light guide plate of the above-described embodiment, and one of the differences is that the light intersection point 223 of any two adjacent point light sources 220 is located in the shape of a bullet. A specific point in the (semi-elliptical shape) corresponds to the focus 143 of the ellipse 140 of the above-described cross-section.

However, the present invention is not limited thereto. In other embodiments, those having ordinary knowledge in the technical field of the present invention may also set the light intersection point of any two adjacent point light sources to be located at the specific point and the bullet shape according to actual needs. Between the straight lines of the semi-elliptical shape, or between the above-mentioned specific points and the convex arc vertices of the cannonball shape (semi-elliptical shape).

4A to 4C are partial enlarged views of other comparative examples according to the present invention, the cross-sectional positions of which are the same as the partial M of Fig. 1. In FIG. 4A, the structure of the light guide plate of this comparative example is substantially the same as the structure of the light guide plate described above. One difference is that the second microstructure pattern 150 has a triangular shape, and the bottom edge 152 of the triangle is substantially aligned with the light side surface 112, a triangle. A diagonal 151 of the bottom edge 152 is located just at the edge of the surface light source area AA. If the second microstructure pattern 150 is a triangle, the inventor detects the optical uniformity of the transition region T on the 32 吋 and 49 导 light guide plates according to the second microstructure pattern 150 of the triangle. 50~70%. By comparison, when the second microstructure pattern is a cannonball shape compared to the second microstructure pattern 150 of the triangle, Better light uniform results are obtained.

In FIG. 4B, the structure of the light guide plate of the comparative example is substantially the same as the structure of the light guide plate. One difference is that the second microstructure pattern 160 has an inverted triangle, and the bottom edge 162 of the triangle is substantially located in the surface light source area AA. The edge, one of the bottom edges 162 of the triangle 161 is exactly aligned with the light incident side 112 of the light guide plate 100. Similarly, the 32 吋 and 49 导 light guide plates were used for sample testing. If the second microstructure pattern 160 was inverted triangle, the optical uniformity of the transition region T was less than 50%. It can be seen that, when the second microstructure pattern 160 is in the shape of a bullet, compared to the second microstructure pattern 160 of the inverted triangle, a better light uniform result can be obtained.

Finally, in FIG. 4C, the above-mentioned 32 吋 and 49 导 light guide plates are still used as the comparative example. One difference is that the second microstructure pattern 170 is square, and the square two opposite sides 171 and 172 are respectively located. The edge of the surface light source area AA and the light incident side 112. The inventors obtained the optical uniformity of the transition region T according to the square second microstructure pattern 170, which is between 60 and 75%. It can be seen that, compared to the square second microstructure pattern 170, when the second microstructure pattern 170 is in the shape of a bullet, a better light uniform result can be obtained.

Thus, since the shape of the projectile is closer to the shape of the light envelope of the point source 220, and as is known from the above comparative examples, only the second microstructure pattern of the bullet shape (semi-elliptical shape) can exhibit better light exiting the light guide plate. The light is evenly distributed. Therefore, the shape of the second microstructure pattern may not be equivalently replaced by any pattern.

Finally, in the various embodiments disclosed above, it is not intended to limit the present invention. The invention can be practiced in the present invention without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

10‧‧‧Side-in backlight module

100‧‧‧Light guide plate

110‧‧‧Translucent plate

111‧‧‧Glossy surface

112‧‧‧light side

120‧‧‧First microstructured pattern

131‧‧‧Optical microstructure

200‧‧‧Light source

210‧‧‧Substrate

220‧‧‧ point light source

222‧‧‧ envelope

AA‧‧‧ surface light source area

M‧‧‧ partial

N‧‧‧ Surrounding Area

T‧‧‧ transitional area

The width of the transition zone of Td‧‧

Claims (8)

A side-lit backlight module includes: a light guide plate, comprising: a light-transmissive plate body, comprising a light-incident side surface and a light-emitting surface adjacent to the light-incident side surface, wherein the light-emitting surface is divided into a light source region and a surrounding a surrounding area of the surface light source region; a first microstructure pattern distributed in the surface light source region; and a plurality of second microstructure patterns located in the surrounding area and linearly arranged along the light incident side; and a light source, The method includes: a substrate; and a plurality of point light sources linearly arranged on the substrate, and spaced apart from the light incident side surface, wherein any two adjacent ones of the point light sources define a spacing region, and each of the plurality of light sources The second microstructure pattern is aligned with one of the spaced regions, wherein each of the second microstructure pattern profiles is formed by an ellipse having an ellipse along its short axis, the bullet shape having a straight line and an arc. The two ends of the arc are respectively connected to the two ends of the straight line to form two opposite end intersections, and one of the arcs has a convex arc vertex closer to the first microstructure pattern than the end intersections, and the length of the line is equal to The distance between any two adjacent of point light sources. The side-entry backlight module of claim 1, wherein each of the point light sources has an envelope of 50% light intensity, and the envelopes of any two adjacent point light sources have a light At the intersection point, the intersection of the light passes through the convex apex of the cannonball shape. The side-entry backlight module of claim 1, wherein each of the point light sources An envelope having a 50% light intensity, and the envelopes of any two adjacent point light sources have a light intersection point, the light intersection point passing through a focus of the ellipse, wherein the focus is on the projectile Within the shape. A light guide plate comprising: a light transmissive plate body comprising a light incident side surface and a light exiting surface adjacent to the light incident side surface, the light exiting surface being divided into a light source region and a surrounding area surrounding the surface light source region; a microstructure pattern distributed in the surface light source region; and a plurality of second microstructure patterns located in the surrounding area and linearly arranged along the light incident side, wherein each of the second microstructure patterns is externally shaped a bullet shape of an ellipse along a short axis thereof, the bullet shape having a straight line and an arc line, and the two ends of the arc are respectively connected to the two ends of the straight line to respectively form two opposite end intersections, and one of the arcs has a convex arc vertex The first microstructure pattern is closer to the end intersections, and the length of the line is equal to the length of the minor axis of the ellipse. The light guide plate of claim 4, wherein one of the surrounding areas has a width equal to one-half the length of one of the major axes of the ellipse. A light guide plate receives a plurality of spaced-apart point light sources on a light-incident side surface, thereby forming a one-side input backlight module, the light guide plate comprising: a light-transmissive plate body including a light source region and a transition region, the transition The region is elongated and located between the surface light source region and the light incident side surface; a first microstructure pattern is distributed in the surface light source region; a plurality of second microstructure patterns, each of the second microstructure patterns being in the shape of a bullet that cuts an ellipse along a short axis thereof, located in the transition region, and interlaced with the spaced point sources Thereby, when the spaced-apart point light sources emit light, the second microstructure patterns form a pseudo light source between any of the spaced-apart point light sources, thereby diluting the optical bright spots. The light guide plate of claim 6, wherein each of the point light sources has an envelope of 50% light intensity, and the envelopes of any two adjacent point light sources have a light intersection point, The point of intersection of the light passes through the convex vertex of the adjacent bullet shape. The light guide plate of claim 6, wherein each of the point light sources has an envelope of 50% light intensity, and the envelopes of any two adjacent point light sources have a light intersection point, The point of intersection of the light passes through a focus of the ellipse, wherein the focus is within the cannonball shape.