TWI706209B - Light guide plate for facilitating local dimming - Google Patents

Abstract

A light guide plate for facilitating local dimming is disclosed. The light guide plate is applied to a direct type light source. The light guide plate includes a main body, a plurality of first elongated grooves and a plurality of second elongated grooves. The main body is a plate-like structure and has a bottom surface and a light exiting surface which are opposed to each other; and the bottom surface corresponds to the direct type light source. The first elongated grooves are laid on the bottom surface, the second elongated grooves are laid on the light exiting surface; wherein the first elongated grooves and the second elongated grooves are vertically staggered in the projection direction, and the extending direction of the first elongated grooves and the second elongated grooves are respectively perpendicular to the main light axis of the direct type light source. Further, the width P ₁of the first elongated grooves and the width P ₂of the second elongated grooves are respectively 150 to 300μm. Thereby, the contract of the area can be enhanced by the condensing and light-blocking characteristics to enhance the local dimming performance in the application.

Description

Light guide plate for section dimming

The present invention is related to the field of light guide plates, and in particular is a light guide plate that is beneficial to section dimming.

Today's display devices are mostly composed of a backlight module and a display panel. The backlight module is arranged on the back side of the display panel to provide uniform light to the display panel and achieve the purpose of displaying images. The backlight module generally contains various optical components such as light guide plates, alignment films, brightness enhancement films and other components, and uses point light sources such as LEDs as the main light source. Through the backlight module, the light of the point light source can be converted into the light to be emitted in a desired state, thereby achieving the effect and purpose of providing light to the display panel. Regarding the position of the point of view light source, the backlight module can be roughly distinguished between direct type and side type. The direct type backlight module refers to the bottom side of the point light source setting module, and the light can enter the structure vertically. The side type backlight module is The point light source is arranged on the side of the module so that the light can be incident sideways.

In order to improve the contrast quality of the display, the backlight module still needs to have the local dimming function. However, the side-type point light source is arranged on the side of the light guide plate, so it is easy to have the problem of uneven brightness, which is not conducive to Section dimming. In the field of direct-lit backlight modules, in the prior art, a diffuser plate is installed in the backlight module to achieve uniform light output and segmental dimming. The function of the diffuser plate is to make the light emitted by the light have the effect of uniform brightness distribution. , But because the principle of the diffuser is to diffuse the light instead of converging, it will consume a considerable degree of brightness, resulting in insufficient brightness of the backlight module. On the other hand, the backlight module using the diffuser plate is prone to obvious halo phenomenon in the application of segment dimming, and it cannot effectively improve the picture contrast of the mounted display.

In view of this, the inventor of the present invention has accumulated rich experience in related industries, and conceived and proposed a light guide plate that is conducive to segment dimming to effectively solve the shortcomings of direct-lit backlight modules in area dimming applications.

One purpose of the present invention is to provide a light guide plate that is conducive to segmental dimming, which has the characteristics of concentrating and isolating light to enhance the contrast of regional light output, thereby enhancing the performance of segmental dimming, and greatly improving the picture of the mounted display display effect.

In order to achieve the above objective, the present invention provides a light guide plate that is conducive to segment dimming in one embodiment for use with a direct-down light source, including: a body, a plate-shaped structure with a bottom surface and a bottom surface The light-emitting surface, the bottom surface and the light-emitting surface are arranged oppositely, and the bottom surface corresponds to the direct light source to receive light; a plurality of first elongated grooves are arranged on the bottom surface; and a plurality of second elongated grooves The grooves are arranged on the light-emitting surface, wherein the first elongated grooves and the second elongated grooves are vertically staggered in the projection direction, and the first elongated grooves The extending directions of the groove and the second elongated grooves are respectively perpendicular to the main optical axis of the direct-lit light source; wherein the width P _{1 of the} first elongated grooves and the second longest The width P ₂ of the strip grooves is between 150 and 300 μm. Thereby, through the first and second elongated grooves arranged vertically and staggered in the range of the aforementioned ruler, and the structural feature that the extending direction of the aforementioned grooves is perpendicular to the main light axis of the direct light source, it is It allows the light guide plate to have a regional light-shielding effect when emitting light, and then achieve accurate and excellent segmental dimming effect when matched with a direct light source.

In order to have better light concentrating and light blocking performance, in another embodiment, it is disclosed that the depth of the first elongated grooves is D ₁ , and conforms to D ₁ : P _{1 is} between 1:3 and 2: The relation of 3.

Further, another preferred solution is to make D ₁ :P ₁ be 1:2, so that the light guide plate can achieve more precise dimming performance.

In still another embodiment, the depth of the second elongated grooves can also be D ₂ and meet the relational expression of D ₂ :P ₂ between 1:3 and 2:3, so that the light guide plate Possesses better light gathering and light blocking efficiency.

Further, under the aforementioned ruler relationship, in order to improve the light adjustment efficiency of the light guide plate, another preferred solution is to make the D ₂ :P ₂ system 1:2, so that the light guide plate can achieve more precise dimming. The effectiveness.

In addition, in one embodiment, the first elongated grooves and the second elongated grooves are V-shaped, respectively, so as to have better light adjusting performance.

On the other hand, in another embodiment, the thickness of the main body is between 1.2-2mm to have the effect of thinning.

In one embodiment, the first elongated grooves and the second elongated grooves are formed by roll forming so as to have better structural accuracy and product yield.

In summary, the light guide plate disclosed in the present invention that is advantageous for segmental dimming is through the long strip grooves arranged on the opposite sides of the light guide plate based on a specific ruler range, and when used with a direct light source, it can be used The characteristics of light-gathering and light-shielding enhance the regional contrast and effectively achieve the effect of section dimming, so that the display device for subsequent applications can have excellent picture contrast. Furthermore, the structural proportions of the first and second elongated grooves can be respectively limited to improve the dimming performance of the light guide plate in application.

As mentioned above, in order to improve the application performance of the direct-lit backlight module so that it can be more conducive to segment dimming control, so that the display device has a better picture contrast, the inventors have continued to design and experiment. Various possible optical structures are designed on the light guide plate and verified to propose products that meet the existing market needs. Under the application of the direct-type architecture, the light guide plate itself has no need for the side-in type light guide plate to be installed with density changes and micro-dots. Therefore, the blank plate can be used for processing and set the required optical structure without the need for the light guide plate. Then set up micro-dot structure. Accordingly, the present inventor proposes to install a grid structure on the light guide plate, and through the grid structure to enhance the light condensing and light blocking effect in each area after the light enters the light guide plate, so that when performing segmental dimming, Each control area can reliably emit light in the required light emitting state. In this regard, the inventors have conceived various implementations and feasible solutions. The following is an example of an experiment in which a grid structure is set on a single side of the light guide plate.

Please refer to Figure 1, which is a three-dimensional schematic diagram of the light guide plate of the experimental example of the present invention. One of the methods proposed by the inventor is to form a grid structure on one side of the light guide plate. As shown in Figure 1, one side 90 of the light guide plate 9 is provided with a grid structure composed of two vertically staggered grooves 91, so that the vertical staggered grooves can be used to adjust the brightness of each area of the light guide plate. However, this structure has some shortcomings in implementation. First, in terms of manufacturing process, only providing two kinds of grooves on a single side destroys the structural integrity of each other, and affects the guidance of light. Second, because it is applied to the light guide plate with the direct-type structure and the segmental dimming function, there is no need to set up the micro-dots. Therefore, when the two grooves are arranged on the same surface, except for the area on the other side of the plate. The waste may also be affected by the slight surface microstructure of the white surface, which will reduce the light guide efficiency.

In view of this, the inventor further conceived a better and more suitable light guide plate structure to improve the aforementioned shortcomings in the manufacturing process and structure. Please refer to FIGS. 2 and 3, which are a three-dimensional schematic diagram of a light guide plate and a direct light source and a schematic diagram of a partial structure of the light guide plate according to an embodiment of the present invention. Here, a light guide plate 1 that is advantageous for segment dimming is disclosed for use with a direct-type light source 2, and includes a main body 10, a plurality of first elongated grooves 11 and a plurality of second elongated grooves 12. Wherein, the direct light source 2 can include a circuit substrate 20 and a plurality of LED light sources 21. The LED light sources 21 are arranged on the circuit substrate 20 and can be arranged in a matrix, and the LED light sources 21 can be used as secondary Millimeter light-emitting diodes (Mini LED) can make the display device used with more precise high dynamic range image (HDR) partition performance.

The body 10 of the light guide plate 1 is a plate-shaped structure and has a bottom surface 101 and a light emitting surface 102. The bottom surface 101 and the light emitting surface 102 are arranged oppositely, and the bottom surface 101 corresponds to the direct light source 2 to receive light. The main body 10 can be a transparent acrylic plate made of PMMA material. The first elongated grooves 11 are arranged on the bottom surface 101, the second elongated grooves 12 are arranged on the light-emitting surface 102, and the first elongated grooves 11 and the second elongated grooves groove 12 in a staggered vertical lines disposed on the projection direction, and the first elongated groove 11 extending in the direction of A ₁ and a second elongated groove 12 extending in the direction of A _2, respectively, of the main direct type light source 2 The axes B are perpendicular to each other. In addition, the width P ₁ of the first elongated groove and the width P ₂ of the second elongated groove are respectively between 150 and 300 μm. Through the first elongated grooves 11 and the second elongated grooves 12 which are arranged separately and whose projection directions are vertically staggered, in addition to the structure of the elongated grooves, the light-concentrating and light-isolating characteristics can be used to strengthen each area The contrast of light output can also increase the margin in the process by arranging long strips of grooves on different surfaces, thereby saving costs and eliminating the lack of structural mutual damage integrity, allowing the light guide plate 1 to be used in the area of direct-type models It can have better light control performance when dimming in segments.

It should be noted that the light guide plate 1 of the present invention is conceived and designed based on the problem that the direct-type structure is difficult to achieve excellent segment dimming effects. Therefore, it is also clearly defined that the light guide plate 1 of the present invention is applied to the direct-type backlight structure . Since the light source direction of the light guide plate is closely related to the design of the optical structure on the light guide plate, the same optical structure corresponding to different light incident directions may produce completely different light control effects, and the current light guide plate development will also first This product is applied to the edge-type backlight architecture or the direct-type backlight architecture to be distinguished first, and then the next optical structure design can be continued. Therefore, with regard to applications such as edge-lit light guide plates, backlight modules, etc., the technology is essentially different from the present invention and cannot be used interchangeably. Further, the first elongated groove 11 and the second elongated groove 12 on the light guide plate 1 of the present invention are on the order of magnitude, which is not a small dot structure of 5-100 μm in the traditional side-entry light guide plate. Rather, it achieves the area dimming performance in direct-type applications through the trench structure limited to the size of 150-300μm. At the same time, the first elongated groove 11 and the second elongated groove 12 do not have the characteristics of traditional micro-dots that control the amount of light through changes in density, size, and depth. In other words, the first elongated groove disclosed in the present invention The strip grooves 11 and the second strip grooves 12 are different from the traditional micro-dot structure on the light guide plate to control the light. In addition to the rulers are completely different and cannot be replaced with each other, the light control design is also They are completely unrelated and should not be confused.

On the other hand, the first elongated groove 11 and the second elongated groove 12 of the present invention are also different in structure and effect from the various grooves conventionally arranged on the side-type light guide plate. In the prior art, the various grooves provided on the surface of the side-entry light guide plate, whether they are provided on one side or both sides of the light guide plate, have the effect of partially replacing the brightness enhancement film (BEF), that is, The light is reflected and straightened through the groove, thereby improving the brightness of the forward light. In the design, its extension direction must be parallel to the main light axis of the side-in LED to reflect and receive the LED light incident on the light guide plate. Straight, achieve the effect of enhancing brightness. However, the first elongated groove 11 and the second elongated groove 12 of the present invention are perpendicular to each other in the projection direction. In a three-dimensional space, the extension direction A of the first elongated groove 11 ₁ and the extending direction A _{2 of the} second elongated groove 12 must be perpendicular to the main light-emitting axis B of the direct light source 2. With the structure shown in Figure 2, the first elongated groove 11 can be seen The extension direction A ₁ , the extension direction A _{2 of the} second elongated groove 12 and the main light output axis B of the direct light source 2 exhibit a relationship corresponding to the xyz axis in the three-dimensional space, respectively.

Further, the light guide plate 1 of the present invention controls the direction of light through the first elongated groove 11 and the second elongated groove 12, so that the light is reflected and aggregated, so as to achieve the effect of regional light emission control, and at the same time allow The light has a uniform light-emitting effect, which is a completely different technical field and level from the diffuser described in the prior art. The following is a description of the difference between the light guide plate designed by the present invention and the traditional diffuser plate. In the application of direct-type architecture, the plate set on the light source must have sufficient heat resistance, otherwise it will be easily deformed by heat. This further affects the light adjustment performance. The diffuser is mainly a yellow plate made of PS plastic board mixed with diffused particles. Compared with the light guide plate 1 body 10 of the present invention, the diffuser is not heat-resistant, so it is very Prone to heat deflection and deformation. In addition, as recorded in the previous technical column of this case, the principle of uniformly atomizing light by diffused particles is to diffuse the light rather than converge, so it is easy to cause the halo effect and form an uneven light emission state with halo. The body 10 of the light guide plate 1 of the invention is based on the principle of light guiding and condensing. The first elongated groove 11 and the second elongated groove 12 are used to control the direction of light, so that the light can be reflected and aggregated to achieve better The light output effect is convenient for segment dimming. On the other hand, as mentioned above, the diffuser particles diffuse the light to achieve the purpose of uniformly atomizing the light, so it will consume a considerable degree of brightness, resulting in the backlight module being not bright enough, and the light guide plate 1 in this case is because it transmits The structure of the first elongated groove 11 and the second elongated groove 12 allows light to be reflected and aggregated to uniformize the light. Therefore, the light guide plate 1 of the present invention has a better brightness performance on the light.

In addition, in the existing backlight applications, there are often films with various optical effects, such as alignment films, brightness enhancement films, anti-glare films and even antibacterial films. Generally, nearly hundreds of films are stacked on top of each other. The structure is set in the backlight film group, and these structures are all extremely thin films (Flim), but the light guide plate 1 of the present invention does not belong to this kind of optical product, but is a plate with a certain thickness The structure body provides the structural stiffness of the applied backlight film group and avoids wrinkles and warpage.

In order to improve the uniformity performance on the light, in one embodiment, the depth of the first elongated grooves 11 is D ₁ , and it conforms to the relational expression that D ₁ :P _{1 is} between 1:3 and 2:3. In this ratio range, the light guide plate 1 body 10 can receive light and pass through the first elongated groove 11 and the second elongated groove 12, after adjustment, the light output can meet the requirements, so as to facilitate the segmentation. Dimming control. Further, an implementation state is to make D ₁ :P ₁ be 1:2 to present better light adjustment performance.

In addition, in addition to making the aspect ratio of the first elongated groove 11 meet the aforementioned range, the depth of the second elongated groove 12 can also be made D ₂ , and D ₂ : P _{2 is} between 1:3 ~2:3 relational expression, this can also effectively improve the regional light blocking effect of the main body 10. An implementation state is to make D ₂ : P ₂ be 1:2 to have better light performance.

Further, the structures of the first elongated groove 11 and the second elongated groove 12 can be V-shaped respectively, so that the V-shaped structure can be used to effectively adjust the light to achieve excellent light-concentrating and light-isolating effects, while emitting light It can still have sufficient brightness.

In addition, in order to meet the current market demand, the thickness T of the body 10 of the present invention is set to be between 1.2-2mm to provide a lighter and thinner optical product and effectively reduce the overall thickness in subsequent applications.

Since the first elongated groove 11 and the second elongated groove 12 are separately provided on the bottom surface 101 and the light-emitting surface 102, in manufacturing, a roller embossing method can be used to form the first elongated groove. The groove 11 and the second elongated groove 12 are formed by rolling. In the actual manufacturing process, roller jigs can be provided on the top and bottom sides of the main body 10, corresponding to the light-emitting surface 102 and the bottom surface 101, and the light-emitting surface 102 and the bottom surface 101 can be simultaneously rolled to form the first strips According to this, in addition to being easier and time-saving in the manufacturing process, it can also improve the accuracy of the structure of the first elongated groove 11 and the second elongated groove 12 Sex.

In summary, the light guide plate disclosed in the present invention that is advantageous for segmental dimming is through long strip grooves arranged on the opposite sides of the light guide plate and has a specific ruler range. When used with a direct light source, Using the characteristics of light gathering and light isolation to enhance the regional contrast, the applied direct-lit backlight module architecture can effectively achieve the segment dimming effect, and the subsequent application of the display device also has excellent picture contrast. Among them, the first and second elongated groove rulers of the present invention are different from the dots applied to the light guide plate of the side-entry structure. Compared with the dot structure, the first and second elongated grooves It is a large-scale structure to ensure that the light can be adjusted as required. The dots of the side-entry light guide plate need to be as small as possible, so as to control the light output state through the density adjustment of the density. And the second long strip groove and the dot structure belong to different technical fields. Regarding the structure ratio of the first and second elongated grooves, they can also be further limited to improve the dimming performance of the light guide plate in application. In the manufacturing process, the first elongated groove and the second elongated groove can be embossed and formed by rollers, which can have better production efficiency and structural accuracy, especially for large-size light guide applications. The manufacturing method of imprinting has better processing efficiency and yield. To reiterate here, the light guide plate disclosed in the present invention is a light guide plate body applied to a direct-down structure. Therefore, its development basis and focus are on the relevant structural design under the direct-down structure, and the side-entry type The light guide plate under the structure does not belong to the same technical basis and field, and the difference between the present invention and the side-entry structure has been described in the previous paragraphs, please refer to the foregoing description. On the other hand, the present invention is also different from the conventional diffuser plate commonly used in direct-lit backlight architecture, except that the light guide plate of the present invention has better light output brightness and regional light isolation effect due to the different principles of light adjustment. Based on the essential difference of materials, the light guide plate of the present invention also has better heat resistance than the diffuser plate, and effectively prevents warping.

〔Experimental example〕

9: Light guide plate

90: side

91: groove

〔this invention〕

1: Light guide plate

10: body

101: Bottom

102: Glossy Surface

11: The first long strip groove

12: The second long strip groove

2: Direct light source

20: Circuit board

21: LED light source

A ₁ : The extension direction of the first elongated groove

A ₂ : The extension direction of the second elongated groove

B: The main light axis of the direct light source

T: The thickness of the body

Figure 1 is a three-dimensional schematic diagram of the light guide plate of the experimental example of the present invention. Figure 2 is a three-dimensional schematic diagram of a light guide plate and a direct light source according to an embodiment of the present invention. FIG. 3 is a schematic diagram of a partial structure of a light guide plate according to an embodiment of the present invention.

1: Light guide plate

10: body

101: Bottom

102: Glossy Surface

11: The first long strip groove

12: The second long strip groove

2: Direct light source

20: Circuit board

21: LED light source

A ₁ : The extension direction of the first elongated groove

A ₂ : The extension direction of the second elongated groove

B: The main light axis of the direct light source

Claims (7)

A light guide plate that is conducive to segmental dimming for use with a straight-down light source, comprising: a body, a plate-shaped structure with a bottom surface and a light emitting surface, the bottom surface and the light emitting surface are arranged oppositely, And the bottom surface corresponds to the direct light source to receive light; a plurality of first elongated grooves are arranged on the bottom surface; and a plurality of second elongated grooves are arranged on the light-emitting surface, wherein the The first elongated grooves and the second elongated grooves are vertically staggered in the projection direction, and the extending directions of the first elongated grooves and the second elongated grooves ， Are respectively perpendicular to the main light axis of the direct-lit light source; wherein the width P _{1 of the} first elongated grooves and the width P ₂ of the second elongated grooves are respectively between 150~ 300μm; where the depth of the first elongated grooves is D ₁ , and it meets the relational expression that D ₁ :P _{1 is} between 1:3 and 2:3. As described in the first item of the scope of patent application, the light guide plate is beneficial to segment dimming, wherein D ₁ :P ₁ is 1:2. A light guide plate that is conducive to segmental dimming for use with a straight-down light source, comprising: a body, a plate-shaped structure with a bottom surface and a light emitting surface, the bottom surface and the light emitting surface are arranged oppositely, And the bottom surface corresponds to the direct light source to receive light; a plurality of first elongated grooves are arranged on the bottom surface; and a plurality of second elongated grooves are arranged on the light-emitting surface, wherein the The first elongated grooves and the second elongated grooves are vertically staggered in the projection direction, and the extending directions of the first elongated grooves and the second elongated grooves ， Are respectively perpendicular to the main light axis of the direct-lit light source; wherein the width P _{1 of the} first elongated grooves and the width P ₂ of the second elongated grooves are respectively between 150~ 300μm; where the depth of the second elongated grooves is D ₂ , and it meets the relational expression of D ₂ :P ₂ between 1:3 and 2:3. As described in item 3 of the scope of patent application, the light guide plate is beneficial to segment dimming, wherein D ₂ :P ₂ is 1:2. As described in item 1 or 3 of the scope of patent application, the light guide plate that is advantageous for segmental dimming, wherein the first elongated grooves and the second elongated grooves are respectively V-shaped. As described in item 1 or 3 of the scope of patent application, the light guide plate is beneficial to segment dimming, wherein the thickness of the body is between 1.2-2mm. As described in item 1 or 3 of the scope of the patent application, the light guide plate is conducive to segmental dimming, wherein the first elongated grooves and the second elongated grooves are formed by rolling .

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