CN113448121A

CN113448121A - Backlight module and display device

Info

Publication number: CN113448121A
Application number: CN202011413709.6A
Authority: CN
Inventors: 宋立伟; 陈彦良
Original assignee: Innolux Display Corp
Current assignee: Innolux Corp
Priority date: 2020-03-27
Filing date: 2020-12-04
Publication date: 2021-09-28

Abstract

A backlight module, comprising: backlight unit and first prism component. The backlight unit has a light-emitting surface and includes a diffusion layer. The first prism element is arranged on the light-emitting surface of the backlight unit and arranged on the diffusion layer. The first prism element comprises a plurality of first prism units, and each first prism unit is provided with a plurality of first prism tops. The top of the first prism faces the light-emitting surface.

Description

Backlight module and display device

Technical Field

The present disclosure relates to a backlight module, and more particularly, to a backlight module having a prism element disposed on a backlight unit.

Background

Backlight modules are commonly used in various electronic devices (e.g., display devices). The existing backlight module can not completely concentrate the emitted light at the center, and still has certain brightness at a relatively inclined viewing angle. This may not meet specific display requirements. Therefore, how to solve the above problems becomes an important issue.

Disclosure of Invention

Some embodiments of the present application provide a backlight module including a backlight unit and a first prism element. The backlight unit has a light-emitting surface and includes a diffusion layer. The first prism element is arranged on the light-emitting surface of the backlight unit and arranged on the diffusion layer. The first prism element comprises a plurality of first prism units, and each first prism unit is provided with a plurality of first prism tops. The top of the first prism faces the light-emitting surface.

Some embodiments of the present disclosure provide a display device, including a display panel and the backlight module, wherein the prism element is disposed between the backlight unit and the display panel.

Drawings

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below, wherein:

fig. 1 shows a perspective view of a backlight module according to some embodiments of the present application.

Fig. 2 is a schematic cross-sectional view illustrating the backlight unit and the first prism unit shown in fig. 1.

Fig. 3 is a diagram illustrating the relative relationship between the brightness and the light-emitting angle of the backlight module shown in fig. 1.

FIG. 4 is a schematic perspective view illustrating a backlight module according to another embodiment of the present application. FIG. 5 shows a cross-sectional schematic view of a display device according to some embodiments of the present application.

Element numbering in the figures:

10. 10A: backlight module

20: display device

50: display panel

100: backlight unit

100S: light emitting surface

110: reflective layer

120: light guide layer

130: diffusion layer

140: brightness enhancement film

200: first prism element

210: first prism unit

210T: first prism top

211: first surface

212: second surface

213: optical surface

250: second prism element

260: second prism unit

260T: second prism top

261. 262: surface of

300: graph table

302. 304, 306: thread

D1, D2: direction of extension

L: light ray

N, N': normal direction

P: unit width

θ₁: first included angle

θ₂: second included angle

θ_i: angle of incidence

θ_m: angle of reflection

θ_n: critical angle

Detailed Description

The present application can be understood by referring to the following detailed description and the accompanying drawings, wherein it is to be noted that, for the sake of easy understanding for the reader and the brevity of the drawings, only a portion of the backlight module and the display device is illustrated in the drawings, and specific elements in the drawings are not necessarily drawn to scale. In addition, the number and size of the elements in the drawings are merely illustrative and are not intended to limit the scope of the present application. Moreover, the use of similar and/or corresponding reference numbers in different embodiments is merely intended to provide a concise description of some embodiments and does not indicate any relationship between the different embodiments and/or structures discussed.

Certain terms are used throughout the description and following claims to refer to particular elements. Those skilled in the art will appreciate that electronic device manufacturers may refer to the same components by different names. This document does not intend to distinguish between components that differ in function but not name. In the following description and claims, the terms "comprising," including, "" having, "and the like are open-ended terms and thus should be construed in a meaning of" including, but not limited to …. Thus, when the terms "comprises," "comprising," and/or "having" are used in the description of the present application, they specify the presence of stated features, regions, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, regions, steps, operations, and/or components.

Furthermore, relative terms, such as "below" or "bottom" and "above" or "top," may be used in embodiments to describe one element's relative relationship to another element of the figures. It will be understood that if the device of the drawings is turned over and upside down, elements described as being on the "lower" side will be elements on the "upper" side.

When a respective member (e.g., a film or region) is referred to as being "on" another member, it can be directly on the other member or there can be other members between the two. On the other hand, when a member is referred to as being "directly on" another member, there is no member between the two. In addition, when a member is referred to as being "on" another member, the two members may be located above or below the other member in a top-down relationship depending on the orientation of the device.

The terms "about," "equal to," or "the same," "substantially," or "approximately" are generally construed as being within 20% of a given value or range, or as being within 10%, 5%, 3%, 2%, 1%, or 0.5% of a given value or range.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, layers and/or sections, these elements, layers and/or sections should not be limited by these terms, but rather should be used to distinguish between different elements, layers and/or sections. Thus, a first element, layer and/or section discussed below could be termed a second element, layer and/or section without departing from the teachings of some embodiments of the present application. In addition, for the sake of brevity, the terms "first", "second", and the like may not be used in the description to distinguish different elements. The first element and/or the second element recited in the claims may be construed as any element conforming to the description in the specification without departing from the scope defined by the appended claims.

In the present application, the thickness, length and width can be measured by an optical microscope, and the thickness can be measured by a cross-sectional image in an electron microscope, but not limited thereto. In addition, there may be some error in any two values or directions for comparison. If the first value is equal to the second value, it implies that there may be an error of about 10% between the first value and the second value; if the first direction is perpendicular to the second direction, the angle between the first direction and the second direction may be between 80 degrees and 100 degrees; if the first direction is parallel to the second direction, the angle between the first direction and the second direction may be between 0 degrees and 10 degrees.

It should be noted that the technical solutions provided in the following different embodiments can be used alternatively, combined or mixed with each other to form another embodiment without departing from the spirit of the present application.

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present application and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Fig. 1 shows a perspective view of a backlight module 10 according to some embodiments of the present application. The backlight module 10 can be applied to an electronic device, and for example, may include a display device, an antenna device (e.g., a liquid crystal antenna), a sensing device, a touch electronic device (touch display), a curved electronic device (curved display), or a non-rectangular electronic device (free shape display), but is not limited thereto. As shown in fig. 1, the backlight module 10 includes a backlight unit 100 and a first prism member 200 disposed on the backlight unit 100. For example, the backlight unit 100 includes a reflective layer 110, a light guide layer 120, a diffuser layer 130, and a brightness enhancement film 140 sequentially stacked along a normal direction N (e.g., substantially parallel to the Z-axis) of the backlight unit 100. In other words, the light guide layer 120 is disposed on the reflective layer 110, the diffuser layer 130 is disposed on the light guide layer 120, and the brightness enhancement film 140 is disposed on the diffuser layer 130, but the present disclosure is not limited thereto. In some embodiments, the backlight unit 100 has a light-emitting surface 100S (e.g., the upper surface of the backlight unit 100), and the first prism element 200 is disposed on the light-emitting surface 100S of the backlight unit 100.

As shown in fig. 1, the backlight module 10 includes a backlight unit 100 and a first prism element 200. The backlight unit 100 includes a diffusion layer 130. The first prism element 200 is disposed on the light emitting surface 100S of the backlight unit 100 and on the diffusion layer 130. The first prism element 200 includes a plurality of first prism units 210. The plurality of first prism units 210 have a plurality of first prism tops 210T. For example, each of the first prism units 210 has a first prism top 210T. The first prism top 210T is disposed facing the light emitting surface 100S. According to some embodiments, the diffusion layer 130 may be disposed between the light guiding layer 120 and the first prism element 200.

The backlight unit 100 may be configured to emit light from a light source (not shown), wherein the light source may include, for example, a submillimeter light emitting diode (mini LED), a micro LED, or a quantum dot light emitting diode (QD, which may be, for example, a QLED, a QDLED), a fluorescent light (fluorescent light), a phosphorescent light (phosphor), or other suitable materials, and the materials may be arranged and combined arbitrarily, but are not limited thereto. In other embodiments, the aforementioned light source may also comprise an Organic Light Emitting Diode (OLED). Although the present embodiment is disclosed above, one skilled in the art may omit the light guiding layer 120 and/or the diffusion layer 130 as required. That is, in some embodiments, only the light guiding layer 120 is disposed between the reflective layer 110 and the brightness enhancement film 140. In other embodiments, only the diffuser layer 130 is disposed between the reflective layer 110 and the brightness enhancement film 140. In other embodiments, no optical film layer is disposed between the reflective layer 110 and the brightness enhancement film 140, but the present disclosure is not limited to the above embodiments.

In some embodiments, the material of the reflective layer 110 includes polyethylene terephthalate (PET), Silver (Silver), and any other suitable material, but is not limited thereto. The reflective layer 110 may be configured to reflect light from the light source toward the display direction of the backlight module 10. In some embodiments, the material of the light guiding layer 120 includes, but is not limited to, polymethyl methacrylate (PMMA), Polycarbonate (PC), Polystyrene (PS), and any other suitable material. The light guide layer 120 may be configured to guide light to an appropriate direction (e.g., the display direction of the backlight module 10). In some embodiments, the material of the diffusion layer 130 includes, but is not limited to, PET, PMMA, SiO2, and any other suitable material. The diffuser layer 130 may be configured to diffuse light to achieve a more uniform display effect. In some embodiments, the material of the brightness enhancement film 140 includes, but is not limited to, PET, PC, Ultraviolet (UV) hardening resin, and any other suitable material. The brightness enhancement film 140 may be configured to enhance the brightness of light passing through the backlight unit 100.

Further, as shown in fig. 1, in the present embodiment, the first prism element 200 includes a plurality of first prism units 210, each of the first prism units 210 having a first prism top 210T. The first prism units 210 may extend along a first direction D1 (e.g., Y-axis direction in fig. 1) and may be arranged along a second direction D2 (e.g., X-axis direction in fig. 1). As shown in fig. 1, a position where the first surface 211 and the second surface 212 are connected in one first prism unit 210 may be defined as a first prism top 210T. The extending direction D1 of the first prism unit 210 may be defined as the extending direction of the first prism top 210T. The first prism element 200 has an optical surface 213 on the opposite side of the first prism top 210T. In some embodiments, optical surface 213 extends in a direction substantially parallel to the X-Y plane. Taking the at least one first prism unit 210 as an example, the at least one first prism unit 210 has a first surface 211 connected to the optical surface 213, and the first surface 211 and the optical surface 213 form a first included angle θ₁. The first prism unit 210 has a second surface 212 connecting the optical surface 213 and the first surface 211. The first surface 211 and the second surface 212 form a second included angle theta₂. In some embodiments, first included angle θ₁Is between 3 ° and 25 °, but is not limited thereto. In some embodiments, first included angle θ₁Is between 10 ° and 15 °, but is not limited thereto. In some embodiments, second included angle θ₂May be non-orthogonal (i.e., the second included angle θ)₂May be obtuse or acute), but is not limited thereto. In some embodiments, second included angle θ₂May be at right angles. The detailed structure of the first prism unit 210 will be further described below with reference to fig. 2.

In some embodiments, the first prism unit 210 has a unit width P. The unit width P may be measured along the second direction D2. In some embodiments, the unit width P may be defined as a width measured along the second direction D2 by the projection of the first prism unit 210 on the optical surface 213. If the value of the unit width P is too large, the display quality may be degraded, which may affect the viewing experience of the user. If the value of the unit width P is too small, the process difficulty may be increased and the production cost may be increased. In some embodiments, the unit width P of the first prism unit 210 may be properly designed, and the unit width P may be greater than 0 and less than 60 μm, but is not limited thereto. In some embodiments, the unit width P can be greater than 10 μm and less than 60 μm. In some embodiments, the unit width P may be greater than 10 μm and less than 40 μm in some embodiments.

Fig. 2 is a schematic cross-sectional view illustrating the backlight unit 100 and the first prism unit 210 shown in fig. 1. As shown in fig. 2, a light L is emitted from the light emitting surface 100S of the backlight unit 100, and the light L is incident to the first prism unit 210 from the first surface 211. The light L has an incident angle θ with respect to a normal direction N of the backlight unit 100_i. In some embodiments, the first prism unit 210 has a refractive index n, and the refractive index n may be in a range of about 1.45 to about 2. The light beam L entering the first prism unit 210 from the first surface 211 is deflected and forms a reflection angle θ with the normal direction N' of the first prism unit 210_mWherein the normal direction N of the backlight unit 100 is substantially parallel to the normal direction N' of the first prism unit 210. In some embodiments, the angle of reflection θ_mAccording to the following formula (1):

in the present embodiment, as long as the reflection angle θ_mGreater than or equal to the critical angle theta_nThe light L is reflected by the optical surface 213 back to the backlight unit 100 and then reflected by the reflective layer 110 of the backlight unit 100 to exit. In some embodiments, the critical angle θ_nAccording to the following formula (2):

it should be understood that the definition of the first surface 211 and the second surface 212 is determined according to the direction of the specific light L entering the first prism unit 210. The positions of the first surface 211 and the second surface 212 may be interchanged as long as the direction in which the light L enters the first prism unit 210 is different. In other words, in other embodiments, when the light L enters the second surface 212, the second surface 212 can be regarded as the first surface 211, and the first surface 211 can be regarded as the second surface 212.

Fig. 3 is a diagram illustrating the relative relationship between the brightness and the light-emitting angle of the backlight module 10 shown in fig. 1. As shown in fig. 3, the horizontal axis of the graph 300 indicates the light exit angle and the vertical axis indicates the luminance, and the higher the peak values of the

lines

302, 304, and 306, the greater the luminance at that position. The line 302 represents an embodiment of the backlight module provided with only the backlight unit 100 without the first prism elements 200. Line 304 represents an embodiment of a backlight module having the first prism element 200 disposed on the backlight unit 100, wherein the first included angle θ of the first prism unit 210₁(as shown in fig. 2) is 15 degrees. Line 306 represents an embodiment of a backlight module having the first prism element 200 disposed on the backlight unit 100, wherein the first included angle θ of the first prism unit 210₁(as shown in fig. 2) is 10 degrees. As can be seen from the graph 300, in the case where the first prism element 200 is not provided, it can be observed that a certain brightness is still provided at a more oblique viewing angle (e.g., approximately 90 degrees, i.e., positions near both sides of the graph 300). However, in the case where the first prism element 200 is provided, it is effectiveThe brightness at more oblique viewing angles is reduced, concentrating the brightness distribution of the light at the central viewing angle (i.e., near 0 degrees), as shown by

lines

304, 306. In addition, by the configuration of the first prism element 200, the brightness of the emergent light at the inclined viewing angle can be reduced, and the effects of concentrating the brightness distribution in the middle viewing angle area and saving energy can be achieved.

Fig. 4 is a schematic perspective view illustrating a backlight module 10A according to other embodiments of the present application. It should be noted that the backlight module 10A shown in the present embodiment may include the same or similar parts as the backlight module 10 shown in fig. 1. These parts will be denoted by the same or similar reference numerals and will not be described in detail below. For example, the backlight module 10A includes a backlight unit 100 and a first prism element 200. The backlight module 10A in the present embodiment is different from the backlight module 10 shown in fig. 1 in that: the backlight module 10A further includes a second prism element 250 disposed on the first prism element 200. The first prism member 200 is disposed between the backlight unit 100 and the second prism member 250. The second prism element 250 includes a plurality of second prism units 260, and the plurality of second prism units 260 have a plurality of second prism tops 260T. For example, each of the second prism units 260 has a second prism top 260T. The second prism top 260T is disposed facing the light emitting surface 100S. In the present embodiment, the plurality of second prism units 260 may extend along the second direction D2 (in fig. 1, for example, the X-axis direction), and may be arranged along the first direction D1 (in fig. 1, for example, the Y-axis direction). The second prism unit 260 may have substantially the same structure as the first prism unit 210, but the extending direction D1 of the first prism unit 210 is different from the extending direction D2 of the prism unit 260. As shown in fig. 4, a position where the surface 261 and the surface 262 are connected in one second prism unit 260 may be defined as a second prism top 260T. The extending direction D2 of the second prism units 260 may be defined as the extending direction of the second prism tops 260T.

In the present embodiment, the extending direction D1 of the first prism unit 210 is substantially parallel to the Y-axis, and the extending direction D2 of the second prism unit 260 is substantially parallel to the X-axis. The extending direction D1 of the first prism unit 210 may be substantially perpendicular to the extending direction D2 of the second prism unit 260, but is not limited thereto. In some embodiments, the included angle between the extending direction D1 of the first prism unit 210 and the extending direction D2 of the second prism unit 260 may be between about 65 ° to about 90 °, but is not limited thereto. By the arrangement of the second prism units 260, the brightness distribution of the light can be further concentrated at the central viewing angle. In the present embodiment, any optical film layer may not be disposed between the first prism unit 210 and the second prism unit 260, but is not limited thereto.

FIG. 5 shows a cross-sectional schematic view of a display device 20 according to some embodiments of the present application. As shown in fig. 5, the display device 20 includes a backlight module (e.g., including a backlight unit 100 and a first prism element 200) and a display panel 50. It should be understood that the backlight module of the display device 20 described in the present embodiment is only an example, and any one of the backlight modules covered by the present application may be used. In some embodiments, the first prism element 200 is disposed between the backlight unit 100 and the display panel 50. In some embodiments, the display panel 50 can be any display panel suitable for being combined with a backlight module. For example, the display panel 50 may include a substrate (not shown) and a display layer (not shown) disposed on the substrate. The substrate may be a flexible substrate or an inflexible substrate, and the material of the substrate may include, for example, glass, sapphire, ceramic, plastic, or other suitable materials, wherein the plastic material may be, for example, Polyimide (PI), polyethylene terephthalate (PET), Polycarbonate (PC), Polyethersulfone (PES), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), or Polyarylate (PAR), other suitable materials, or a combination thereof, but is not limited thereto. In some embodiments, the display layer may include a liquid crystal layer, wherein the material of the liquid crystal layer may include, for example, nematic liquid crystal (nematic), smectic liquid crystal (symmetric), cholesteric liquid crystal (cholesteric), Blue phase liquid crystal (Blue phase), or any other suitable liquid crystal material.

In summary, embodiments of the present application provide a backlight module having a prism element disposed on a backlight unit. By arranging the prism top of the prism unit of the prism element to face the light-emitting surface of the backlight unit, the light-emitting brightness at the more inclined viewing angle can be effectively reduced, and the brightness distribution of the backlight module is concentrated at the central viewing angle (i.e. the position close to 0 degree). Therefore, more ideal brightness distribution of the backlight module can be obtained, or the effect of energy saving can be achieved.

Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A backlight module, comprising:

a backlight unit having a light-emitting surface, the backlight unit including a diffusion layer; and

and a first prism element arranged on the light-emitting surface of the backlight unit and arranged on the diffusion layer, wherein the first prism element comprises a plurality of first prism units, the plurality of first prism units are provided with a plurality of first prism tops, and the plurality of first prism tops are arranged facing the light-emitting surface.

2. The backlight module of claim 1, wherein the first prism element has an optical surface on an opposite side of the top of the first prisms, at least one first prism unit has a first surface connecting to the optical surface, the first surface and the optical surface form a first included angle, and the first included angle ranges from 3 ° to 25 °.

3. The backlight module of claim 2, wherein the at least one first prism unit has a second surface connecting the optical surface and the first surface, and the first surface and the second surface form a second included angle, the second included angle being an obtuse angle.

4. The backlight module of claim 1, wherein the unit width of at least one first prism unit is greater than 0 and less than 60 μm.

5. The backlight module of claim 1, wherein the refractive index of the first prism element ranges from 1.45 to 2.

6. The backlight module as claimed in claim 1, further comprising a second prism element, wherein the first prism element is disposed between the backlight unit and the second prism element, the second prism element comprises a plurality of second prism units having a plurality of second prism tops disposed facing the light emitting surface.

7. The backlight module of claim 6, wherein an included angle between the extending direction of the first prism unit and the extending direction of the second prism unit ranges from 65 ° to 90 °.

8. The backlight module of claim 6, wherein no optical film is disposed between the first prism unit and the second prism unit.

9. The backlight module of claim 1, wherein the backlight unit comprises a light guide layer, and wherein the diffuser layer is disposed between the light guide layer and the first prism element.

10. A display device comprising a display panel and the backlight module of claim 1, wherein the first prism element is disposed between the backlight unit and the display panel.