Backlight module and display device

Abstract

The present disclosure provides a backlight module and a display device, and belongs to the technical field of display. The backlight module can solve the problems of low light emission efficiency and harmful blue light doping of the existing backlight module. The backlight module comprises: a light-emitting substrate emitting first color light, at least part of the first color light being first preset waveband light; a color conversion layer comprising a plurality of color conversion units; the color conversion units are configured to emit light of a corresponding color under the excitation of the first color light; at least part of the light emitted by the color conversion layer is second preset waveband light; and a first filter film layer and a second filter film layer; the light entrance surface of at least part of the color conversion units is opposite to the first filter film layer, and the light exit surface is opposite to the second filter film layer; the first filter film layer is configured to transmit the first preset waveband light; and the second filter film layer is configured to transmit the second preset waveband light. The backlight module has high light emission efficiency and can effectively reduce harmful blue light.

Description

Backlight module and display device Technical Field

[0001] This disclosure belongs to the field of display technology, specifically relating to a backlight module and a display device. Background Technology

[0002] Quantum dots (QDs) are nanocrystalline particles with radii smaller than or close to the Bohr exciton radius, typically ranging from 1 nm to 20 nm in size. Quantum dots exhibit quantum confinement effects, emitting fluorescence when excited. Furthermore, they possess unique luminescence properties, such as broad excitation peaks, narrow emission peaks, and tunable emission spectra, making them promising candidates for applications in optoelectronics. Simply put, by applying a certain voltage or light pressure to these nanoscale semiconductor materials, quantum dots emit light of a specific frequency, and the frequency of this light changes with the size of the quantum dot.

[0003] Based on their light-emitting principles, quantum dots are further divided into photoluminescent quantum dots and electroluminescent quantum dots. Light-emitting diodes (LEDs) using electroluminescent quantum dots are often called quantum dot light-emitting diodes (QLEDs). QLEDs are structurally similar to organic light-emitting diodes (OLEDs), the only difference being that the electroluminescent layer in a QLED is a quantum dot light-emitting layer. Electroluminescent quantum dots belong to self-emissive technology, while photoluminescent quantum dots belong to backlight emission technology; the two technologies are fundamentally different.

[0004] The light-emitting principle of QLED is as follows: the quantum dot light-emitting layer is located between the electron transport layer and the hole transport layer. An external electric field causes electrons and holes to move into the quantum dot light-emitting layer, where they are captured and recombine, thereby emitting photons. The principle of photoluminescent quantum dot technology is that when a quantum dot is struck by light, it can emit light of its own color. Typically, a blue LED is used as the backlight, and different colored (e.g., red or green) quantum dot light-emitting layers are placed on its light-emitting side. The blue light generated by the backlight provides photon energy to the different colored quantum dot layers, causing them to emit different colors. Therefore, display devices based on photoluminescent quantum dots may have the following problems: 1. They cannot eliminate harmful blue light; 2. The red or green light emitted by the quantum dot layer is mixed with a large amount of blue light, resulting in impure light emission. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. On one hand, it provides a backlight module comprising: a light-emitting substrate configured to emit light of a first color, at least a portion of which is light of a first preset wavelength; a color conversion layer disposed on the light-emitting side of the light-emitting substrate; the color conversion layer comprising a plurality of color conversion units; the color conversion units configured to emit light of a corresponding color when excited by the first color light; at least a portion of the light emitted by the color conversion layer is light of a second preset wavelength; wherein the backlight module further comprises a first filter layer disposed between the light-emitting substrate and the color conversion layer, and a second filter layer disposed on the side of the color conversion layer facing away from the light-emitting substrate; at least a portion of the light-incident surfaces of the color conversion units are opposite to the first filter layer, and their light-emitting surfaces are opposite to the second filter layer; the first filter layer is configured to transmit light of the first preset wavelength; the second filter layer is configured to transmit light of the second preset wavelength.

[0006] In some examples, the plurality of color conversion units include a first color conversion unit and a second color conversion unit; the first color conversion unit is configured to emit light of a second color when excited by light of the first color; the second color conversion unit is configured to emit light of a third color when excited by light of the first color; the light incident surfaces of both the first color conversion unit and the second color conversion unit are opposite to the first filter layer, and the light emitting surfaces of both are opposite to the second filter layer.

[0007] In some examples, the color conversion layer further includes a transmission unit for transmitting light of the first color; the first filter film layer includes a first filter portion and a first light-transmitting portion, and the second filter film layer includes a second filter portion and a second light-transmitting portion; the light-incident surfaces of the first color conversion unit and the second color conversion unit are both opposite to the first filter portion, and the light-exiting surfaces of both are opposite to the second filter portion; the incident surface of the transmission unit is opposite to the first light-transmitting portion, and the light-exiting surface is opposite to the second light-transmitting portion.

[0008] In some examples, the color conversion layer further includes a third color conversion unit; the third color conversion unit is configured to emit light of the first color when excited by the first color light; the first filter film layer includes a first filter portion and a first transmittance portion, and the second filter film layer includes a second filter portion and a second transmittance portion; the light incident surfaces of both the first color conversion unit and the second color conversion unit are opposite to the first filter portion, and the light emitting surfaces of both are opposite to the second filter portion; the incident surface of the third color conversion unit is opposite to the first transmittance portion, and the light emitting surface is opposite to the second transmittance portion.

[0009] In some examples, the color conversion layer further includes a transmission unit for transmitting the first color light; the light-incident surface of the transmission unit is opposite to the first filter layer, and the light-exit surface is opposite to the second filter layer.

[0010] In some examples, the plurality of color conversion units further includes a third color conversion unit; the third color conversion unit is configured to emit light of the first color when excited by the first color light; the light-incident surface of the third color conversion unit is opposite to the first filter film layer, and the light-emitting surface is opposite to the second filter film layer.

[0011] In some examples, the first color is blue, the second color is red, and the third color is green; the maximum value in the first preset wavelength band is 490nm; and the second preset wavelength band is 450nm-700nm.

[0012] In some examples, the plurality of color conversion units includes a first color conversion unit, a second color conversion unit, and a third color conversion unit; the first color conversion unit is configured to emit light of a second color when excited by light of the first color; the second color conversion unit is configured to emit light of a third color when excited by light of the first color; the third color conversion unit is configured to emit light of the first color when excited by light of the first color; the first filter film layer includes a first filtering portion and a first transmitting portion, and the second filter film layer includes a second filtering portion and a second transmitting portion; the light incident surfaces of the first color conversion unit and the second color conversion unit are both opposite to the first transmitting portion, and the light emitting surfaces of the first and second color conversion units are both opposite to the second transmitting portion; the light incident surface of the third color conversion unit is opposite to the first filter portion, and the light emitting surface is opposite to the second filter portion.

[0013] In some examples, the first color is blue, the second color is red, and the third color is green; the maximum value in the first preset wavelength band is 490nm; and the second preset wavelength band is 450nm-490nm.

[0014] In some examples, the first filter layer and / or the second filter layer comprises silicon dioxide and titanium dioxide.

[0015] In some examples, the color conversion unit includes a quantum dot light-emitting layer.

[0016] In some examples, there is a gap between two adjacent color conversion units.

[0017] In some examples, the spacer comprises an organic insulating material.

[0018] In some examples, the backlight module further includes: a light guide plate opposite to the light-emitting surface of the light-emitting substrate; a first filter film layer disposed on the side of the light guide plate away from the light-emitting substrate; and a barrier layer disposed on the side of the color conversion layer away from the light-emitting substrate; and a second filter film layer disposed on the side of the barrier layer away from the light-emitting substrate.

[0019] In a second aspect, the present invention provides a display device comprising a backlight module as described in any of the above examples. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the disclosure and do not constitute a limitation thereof. The above and other features and advantages will become more apparent to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 is a schematic diagram of the structure of a liquid crystal display device in the related art;

[0022] Figure 2 is a schematic diagram of the backlight module structure based on photoluminescent quantum dots in related technologies;

[0023] Figure 3 is a schematic diagram of the backlight module provided in Embodiment 1 of this disclosure;

[0024] Figure 4 is the optical path diagram of the light in the backlight module shown in Figure 3;

[0025] Figure 5 is a schematic diagram of the transmission unit in Embodiment 1 of this disclosure;

[0026] Figure 6 is a schematic diagram of the third color conversion unit in Embodiment 1 of this disclosure;

[0027] Figure 7 is a schematic diagram showing that the light-incident surface and the light-exit surface of the transmission unit in Embodiment 1 of this disclosure are respectively opposite to the first filter film layer and the second filter film layer;

[0028] Figure 8 is the optical path diagram of the light in the backlight module shown in Figure 7;

[0029] Figure 9 is a schematic diagram showing that the light-incident surface and the light-exit surface of the third color conversion unit in Embodiment 1 of this disclosure are respectively opposite to the first filter film layer and the second filter film layer;

[0030] Figure 10 is the optical path diagram of the light in the backlight module shown in Figure 9;

[0031] Figure 11 is a schematic diagram of the backlight module provided in Embodiment 2 of this disclosure;

[0032] Figure 12 is the optical path diagram of the blue light in the backlight module shown in Figure 11;

[0033] Figure 13 shows the excitation spectrum of the color conversion layer in the backlight module provided in this disclosure;

[0034] Figure 14 shows the transmission spectra of the short-pass filter SPF, the first long-pass filter LPF1, and the second long-pass filter LPF2;

[0035] Figure 15 is a schematic diagram of the light guide plate and the barrier layer in the backlight module provided in this disclosure;

[0036] Figure 16 is an exploded view of the structure of the display device provided in this disclosure.

[0037] The attached figures are labeled as follows:

[0038] 1. Backlight module; 2. Display panel; 21. First substrate; 22. Second substrate; 23. Liquid crystal layer; 11. Light-emitting substrate; 13. First barrier layer; 14. Second barrier layer; 20. Color conversion layer; 30. First filter layer; 40. Second filter layer; 201. First color conversion unit; 202. Second color conversion unit; 204. Transmission unit; 301. First filter section; 302. First light-transmitting section; 401. Second filter section; 402. Second light-transmitting section; 203. Third color conversion unit; 50. Spacer section; 60. Light guide plate; 70. Barrier layer; 3. First polarizer; 4. Second polarizer. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “including,” “comprising,” or “containing,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0041] As used herein, “parallel” and “perpendicular” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°.

[0042] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0043] This document describes exemplary embodiments with reference to sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Therefore, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. Thus, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0044] Traditional liquid crystal displays (LCDs) typically use blue light-emitting diodes (LEDs) paired with phosphors as backlights. However, the limited emission spectrum of phosphors results in suboptimal display performance for LCDs. To address this issue, quantum dot emissive layers are widely used in the display field. For example, photoluminescent quantum dot materials are applied to LCD backlights, effectively improving color purity and saturation.

[0045] Figure 1 is an exploded view of the structure of a liquid crystal display device. As shown in Figure 1, the liquid crystal display device mainly consists of two parts: a display panel 2 and a backlight module 1.

[0046] The display panel 2 includes a first substrate 21 and a second substrate 22 disposed opposite to each other, and a liquid crystal layer 23 located between the first substrate 21 and the second substrate 22; specifically, the first substrate 21 may be an array substrate, and the second substrate 22 may be a color filter substrate.

[0047] The array substrate typically includes a first substrate, thin-film transistors disposed on the side of the first substrate near the liquid crystal layer 23, and pixel electrodes connected to the drains of the thin-film transistors. The color filter substrate typically includes a second substrate and a common electrode formed on the side of the second substrate near the liquid crystal layer 23. When different voltages are applied to the pixel electrode and the common electrode, a vertical electric field is generated between them. Under the action of this vertical electric field, the liquid crystal molecules in the liquid crystal layer 23 will deflect. The rotation state of the liquid crystal molecules is different under different electric fields, and the modulation effect on the light passing through the liquid crystal layer 23 is also different, thereby enabling the display panel to achieve multi-grayscale image display. Of course, the pixel electrode and the common electrode can both be disposed on the side of the array substrate near the liquid crystal layer 23. In this case, when different voltages are applied to the pixel electrode and the common electrode, a horizontal electric field will be generated between them. Under the action of this horizontal electric field, the liquid crystal molecules in the liquid crystal layer 23 will also deflect, thereby modulating the light passing through the liquid crystal layer 23 and enabling the display panel to achieve multi-grayscale image display.

[0048] In addition, the color filter substrate typically includes a black matrix, red color resist, green color resist, blue color resist, and columnar spacers formed on the side of the second substrate near the liquid crystal layer 23. Typically, the display panel can be divided into multiple pixel units arranged in an array. Each pixel unit can include three sub-pixels, such as red, green, and blue sub-pixels; of course, each pixel unit can also include four sub-pixels, such as red, green, blue, and white (or yellow) sub-pixels. The color resist units of each color in the color filter substrate correspond to the sub-pixel units of that color.

[0049] The basic principle of the backlight module 1 is to provide a uniformly bright surface light source for a non-self-emissive liquid crystal display panel, enabling the liquid crystal display device to display. The backlight module 1 typically includes a backlight unit (BLU) and its driving circuitry (not shown). Common backlight sources include LEDs, Mini-LEDs, OLEDs, and quantum dot light-emitting diodes. The light-emitting mechanism of quantum dots can be electroluminescence or photoluminescence. The backlight modules provided in this disclosure are all designed based on the principle of quantum dot photoluminescence.

[0050] Figure 2 shows a backlight module 1 using a quantum dot light-emitting layer in the related technology. As shown in Figure 2, the backlight module 1 includes: a light-emitting substrate 11, a color conversion layer 20, a first barrier layer 13, and a second barrier layer 14. The light-emitting substrate 11 is configured to emit light of a first color, for example, blue. In this case, the light-emitting substrate 11 may include a substrate, a driving circuit formed on the substrate, and a blue light-emitting chip electrically connected to the driving circuit, wherein the blue light-emitting chip is connected to the driving circuit by bonding. A color conversion layer 20 is disposed on the light-emitting side of the light-emitting substrate 11. It typically includes quantum dot light-emitting units that emit different colors of light. For example, the color conversion layer 20 includes a first color conversion unit 201 and a second color conversion unit 202, wherein the first color conversion unit 201 and the second color conversion unit 202 are respectively configured to convert the blue light emitted by the light-emitting substrate 11 into light of a second color and a third color, for example, the second color is red and the third color is green. Therefore, the first color conversion unit 201 may include red quantum dots emitting red light, and the second color conversion unit 202 may include green quantum dots emitting green light. A first barrier layer 13 and a second barrier layer 14 may be located on opposite sides of the color conversion layer 20, and both the first barrier layer 13 and the second barrier layer 14 have a certain thickness to prevent the color conversion layer 20 from being corroded by water and oxygen. Of course, to achieve a thinner and lighter display device, the first barrier layer 13 and the second barrier layer 14 may not be provided in the backlight module 1 of the display device.

[0051] The following is a brief introduction to the light-emitting principle and light-emission process of the backlight module 1 shown in Figure 2. The principle of quantum dot photoluminescence is that quantum dots of different sizes can emit light of a color corresponding to their size when illuminated by light of a specific wavelength. Therefore, by reasonably setting the size of the quantum dots, quantum dots emitting different colors of light can be obtained. Thus, the colors referred to as "red quantum dots," "green quantum dots," or "blue quantum dots" in this article do not represent the color of the quantum dots themselves, but rather the color of the light emitted by quantum dots of different sizes. Taking the example of the light-emitting substrate 11 emitting blue light, the first color conversion unit 201 including red quantum dots, and the second color conversion unit 202 including green quantum dots, the light-emitting process of the backlight module 1 is introduced: the light-emitting substrate 11 emits blue light BL0, which provides excitation energy to the red quantum dots and green quantum dots placed on the light-emitting side of the light-emitting substrate 11. After being excited by the blue light BL0, the red quantum dots emit red light RL0, and at the same time, the green quantum dots emit green light GL0 after being excited by the blue light BL0. The other areas are irradiated by the blue light BL0 emitted by the light-emitting substrate 11.

[0052] However, the backlight module 1 in the aforementioned related technologies may have the following problems: 1. Since the blue light BL0 emitted by the light-emitting substrate 11 does not fully participate in the excitation of the color conversion layer 20, the backlight module 1 suffers from low luminous efficiency and high power consumption of the display device; 2. Since the blue light BL0 emitted by the light-emitting substrate 11 does not fully participate in the excitation of the color conversion layer 20, the red light RL0 and green light GL0 emitted by the red quantum dots and green quantum dots respectively may be doped with blue light BL0 emitted by the light-emitting substrate 11 that has not participated in the excitation process, thus causing the problem of impure color of the light emitted by different quantum dots in the backlight module 1, that is, the light emitted by the red quantum dots is actually... Red light doped with blue light BL0, i.e., RL0+BL0, while the light actually emitted by the green quantum dot is green light doped with blue light BL0, i.e., GL0+BL0; 3. Typically, the wavelength of blue light BL0 is between 400nm and 500nm, including harmful blue light BL01. Those skilled in the art will understand that harmful blue light BL01 refers to high-energy blue light emitted by the display screen, typically with a wavelength range of 400nm-450nm. This type of blue light has high energy and can penetrate the cornea and lens of the eye, directly irradiating the retina; therefore, when the light emitted by the backlight module 1 contains harmful blue light BL01, there is a high probability that it will affect the user's health.

[0053] To address at least one of the aforementioned technical problems, this disclosure provides a backlight module 1. Figures 3-11 illustrate several exemplary structures of the backlight module 1 provided by this disclosure. Referring to Figures 3-11, the backlight module 1 provided by this disclosure includes a light-emitting substrate 11, a color conversion layer 20, a first filter layer 30, and a second filter layer 40. The light-emitting substrate 11 is configured to emit light of a first color, at least a portion of which is light of a first preset wavelength. The color conversion layer 20 is disposed on the light-emitting side of the light-emitting substrate 11, and includes multiple color conversion units. Each color conversion unit is configured to emit light of a corresponding color when excited by the first color light. At least a portion of the light emitted by the color conversion layer 20 is light of a second preset wavelength. The first filter layer 30 is disposed between the light-emitting substrate 11 and the color conversion layer 20 and is configured to transmit light of a first preset wavelength band; the second filter layer 40 is disposed on the side of the color conversion layer 20 away from the light-emitting substrate 11 and is configured to transmit light of a second preset wavelength band; and at least some of the light-incident surfaces of the color conversion units are opposite to the first filter layer 30 and the light-emitting surfaces are opposite to the second filter layer 40.

[0054] Depending on the number and type of color conversion units in the color conversion layer 20, and the different types of color conversion units opposite to the first filter layer 30 and the second filter layer 40, the backlight module 1 provided in this disclosure can have various different structures. The specific structure of the backlight module 1 provided in this disclosure and its beneficial effects are described below, using the backlight module 1 shown in Figures 3-10 as Embodiment 1 and the backlight module 1 shown in Figures 11-12 as Embodiment 2.

[0055] It should be noted that the color conversion unit in this embodiment can be a phosphor or a quantum dot. In the following detailed description, we will use a quantum dot as the color conversion unit, with the first color being blue, the second color being red, and the third color being green as an example. Accordingly, in the following embodiment, the first color conversion unit 201 is a red quantum dot, the second color conversion unit 202 is a green quantum dot, and the third color conversion unit 203 is a blue quantum dot. It should also be noted that in some other embodiments, the light emitted by the light-emitting substrate 11 may be a color other than blue. In this case, the second and third colors can also be adjusted according to the color of the light emitted by the light-emitting substrate 11, that is, the size of the quantum dots in the first color conversion unit 201 and the second color conversion unit 202 can be adjusted accordingly.

[0056] Example 1:

[0057] Figure 3 is an exploded view of the backlight module 1 in Embodiment 1. As shown in Figure 3, the backlight module 1 includes a light-emitting substrate 11, a color conversion layer 20, a first filter layer 30, and a second filter layer 40. The light-emitting substrate 11 is configured to emit light of a first color, i.e., blue light, at least a portion of which is light of a first preset wavelength. The color conversion layer 20 is disposed on the light-emitting side of the light-emitting substrate 11 and includes multiple color conversion units, including a first color conversion unit 201 and a second color conversion unit 202. The first color conversion unit 201 is configured to emit light of a second color, i.e., red light, when excited by the first color light; the second color conversion unit 202 is configured to emit light of a third color, i.e., green light, when excited by the first color light. The first color conversion unit 201 uses red quantum dots, and the second color conversion unit 202 uses green quantum dots. As shown in Figure 3, in this embodiment, the light-incident surfaces of both the red and green quantum dots are opposite to the first filter layer 30, and the light-exiting surfaces are opposite to the second filter layer 40.

[0058] Typically, blue light has a wavelength of 400nm-500nm, red light has a wavelength of 580nm-680nm, and green light has a wavelength of 500nm-570nm. In this embodiment, the maximum value in the first preset wavelength band is 490nm; the second preset wavelength band is 450nm-700nm. It should be noted that the wavelength ranges of various colors of light described here are only schematic approximate ranges and do not imply any limitation on the wavelengths of the light emitted by each color conversion unit.

[0059] Figure 4 shows the optical path of light after passing through each film layer in the backlight module 1 shown in Figure 3. As shown in Figure 4, the light directly emitted by the light-emitting substrate 11 is blue light BL0, with a wavelength in the range of 400nm-500nm. When multiple color conversion units include red quantum dots and green quantum dots, and the light-incident surfaces of the red and green quantum dots are both opposite the first filter film layer 30, and the light-emitting surfaces are both opposite the second filter film layer 40, the blue light BL0 directly emitted by the light-emitting substrate 11 roughly goes through the following three processes. The following description only uses the light path in the red quantum dot region as an example to illustrate the optical path of blue light BL0.

[0060] Process 1: Since the first filter layer 30 can only transmit light with wavelengths below 490nm, the blue light BL0 (400nm-500nm) will be transmitted as blue light BL02 after passing through the first filter layer 30, with a wavelength between 400nm and 490nm.

[0061] Process 2: When the blue light BL02 (400nm-490nm) reaches the color conversion layer 20, the red quantum dot is excited by the blue light BL02 (400nm-490nm) and emits red light RL0 (580nm-680nm); however, not all the blue light BL02 (400nm-490nm) participates in the excitation. Therefore, the light emitted by the red quantum dot should be red light RL0 (580nm-680nm) doped with blue light BL02 (400nm-490nm) that did not participate in the excitation process. That is, the emitted light should be RL0 (580nm-680nm) + BL02 (400nm-490nm).

[0062] Process 3: Since the second filter layer 40 only transmits light with wavelengths in the 450nm-700nm range, when the light RL0 (580nm-680nm) + BL02 (400nm-490nm) reaches the second filter layer 40, the blue light BL01 with wavelengths in the 400nm-450nm range will be reflected back to the red quantum dot by the first filter layer 40, exciting the red quantum dot again, causing it to emit red light RL1 again. The wavelength of 1 is between 580nm and 680nm. After propagating to the first filter layer 30, it is reflected by the first filter layer 30 and then emitted from the side of the red quantum dot closer to the second filter layer 40. Since the wavelength of the red light RL1 is within the transmission band of the second filter layer 40 (450nm-700nm), the red light RL1 can eventually be emitted from the second filter layer 40. Therefore, the light emitted from the red quantum dot through the second filter layer 40 consists of red light RL0 and red light RL1.

[0063] It should be noted that the light path of the blue light BL0 incident on the region where the green quantum dot is located is similar to that in the region where the red quantum dot is located. The only difference is the color of the outgoing light, which will not be described in detail here.

[0064] As can be seen from the optical path diagram shown in Figure 4, the backlight module 1 shown in Embodiment 1, compared with the prior art, can produce at least one of the following beneficial effects: 1. By setting a first filter film layer 30 on the light-incident side of the color conversion layer 20, and setting the first filter film layer 30 to only transmit light with wavelengths below 490nm, the light emitted by the color conversion unit (wavelength not less than 490nm) can be reflected back to the color conversion unit for excitation when it propagates to the first filter film layer 30, thereby improving the luminous efficiency of the color conversion unit; 2. By setting a second filter film layer 40 on the light-outcident side of the color conversion layer 20, and setting the first filter film layer 30 to only transmit light with wavelengths below 490nm, the light emitted by the color conversion unit (wavelength not less than 490nm) can be reflected back to the color conversion unit for excitation, thereby improving the luminous efficiency of the color conversion unit; The second filter layer 40 can only transmit light with wavelengths between 450nm and 700nm. On the one hand, it can filter out the blue light mixed in with red and green light, making the red and green light emitted by the backlight module 1 more pure. Of course, the second filter layer 40 also filters out the harmful blue light with higher energy in red and green light, thereby avoiding the harmful blue light from affecting the user's health. On the other hand, the second filter layer 40 can make the blue light that has not participated in the excitation process reflect back to the color conversion unit to participate in the excitation after it propagates to the second filter layer 40, thereby improving the luminous efficiency of the color conversion unit.

[0065] In some examples, in the backlight module 1 provided in Embodiment 1, the color conversion layer 20 further includes a transmission unit 204, as shown in Figure 5. As shown in Figure 5, the color conversion layer 20 includes red quantum dots, green quantum dots, and the transmission unit 204, which is configured to transmit light of a first color, i.e., blue light. The first filter layer 30 includes a first filter portion 301 and a first light-transmitting portion 302, and the second filter layer 40 includes a second filter portion 401 and a second light-transmitting portion 402. In this example, the light-incident surfaces of both the red and green quantum dots are opposite to the first filter portion 301, and their light-exiting surfaces are opposite to the second filter portion 401; and the incident surface of the transmission unit 204 is opposite to the first light-transmitting portion 302, and its light-exiting surface is opposite to the second light-transmitting portion 402.

[0066] For example, the transmission unit 204 can be a transparent medium such as glass, water, or air, or it can be a thin film, grating, multilayer film, or photonic crystal that can transmit blue light.

[0067] In some examples, the backlight module 1 provided in Embodiment 1 further includes a third color conversion unit 203 in its color conversion layer 20. Figure 6 is a schematic diagram of the third color conversion unit 203. As shown in Figure 6, the third color conversion unit 203 is configured to emit blue light when excited by blue light. The third color conversion unit 203 is exemplified as a blue quantum dot in the following examples. The first filter layer 30 includes a first filter portion 301 and a first light-transmitting portion 302, and the second filter layer 40 includes a second filter portion 401 and a second light-transmitting portion 402. In this example, the light-incident surfaces of the red and green quantum dots are opposite to the first filter portion 301, and the light-exiting surfaces are opposite to the second filter portion 302. The light-incident surface of the blue quantum dot is opposite to the first light-transmitting portion 301, and the light-exiting surface is opposite to the second light-transmitting portion 302.

[0068] In some examples, in the backlight module 1 provided in Embodiment 1, the color conversion layer 20 further includes a transmission unit 204 for transmitting blue light; and the light-incident surface of the transmission unit 204 is opposite to the first filter layer 30, and the light-exiting surface is opposite to the second filter layer 40. Figure 7 is a schematic diagram showing that the light-incident surface and the light-exiting surface of the transmission unit 204 are opposite to the first filter layer 30 and the second filter layer 40, respectively.

[0069] Figure 8 shows the optical path of the blue light BL0 in the backlight module 1 shown in Figure 7 at the red quantum dot, green quantum dot and transmission unit 204 region. The optical path of the blue light BL0 at the red quantum dot and green quantum dot is the same as that in Figure 4 above, and will not be repeated here. Only the optical path of the blue light BL0 at the transmission unit 204 region is introduced.

[0070] As shown in Figure 8, the optical path of the blue light BL0 in the region of the transmission unit 204 is roughly as follows: after the blue light BL0 (400nm-500nm) passes through the first filter layer 30, the transmitted light is the blue light BL02 (400nm-490nm); after the blue light BL02 (400nm-490nm) passes through the transmission unit 204, it propagates to the second filter layer 40. Since the second filter layer 40 can only transmit light with wavelengths between 450nm and 700nm, the light finally transmitted from the second filter layer 40 is the blue light BL02-BL01 with wavelengths between 450nm and 490nm, where the blue light BL01 refers to the light with wavelengths between 400nm and 450nm.

[0071] As can be seen, in the above example, by placing the light-incident surface and the light-exit surface of the transmission unit 204 opposite to the first filter film layer 30 and the second filter film layer 40 respectively, and the second filter film layer 40 can only transmit light in the 450nm-700nm wavelength band, in addition to having the beneficial effects that can be produced by the above embodiment 1, it also has the following further effects: for the blue light transmitted in the area of ​​the transmission unit 204, it can effectively filter out the harmful blue light with high energy (wavelength of 400nm-450nm), and avoid the harmful blue light emitted by the backlight module 1 from having an adverse effect on the user's health.

[0072] In some examples, in the backlight module 1 provided in Embodiment 1, the multiple color conversion units further include blue quantum dots; and the light-incident surface of the blue quantum dots faces the first filter layer 30, and the light-emitting surface faces the second filter layer 40. Figure 9 is a schematic diagram showing that the light-incident surface and the light-emitting surface of the blue quantum dots face the first filter layer 30 and the second filter layer 40, respectively.

[0073] Figure 10 shows the optical path of the blue light BL0 in the backlight module 1 shown in Figure 9 at the red quantum dot, green quantum dot and blue quantum dot regions. The optical path of the blue light BL0 at the red quantum dot and green quantum dot regions is the same as that in Figure 4 above, and will not be repeated here. Only the optical path of the blue light BL0 at the blue quantum dot region will be introduced.

[0074] As shown in Figure 10, the optical path of blue light BL0 at the blue quantum dot region is roughly as follows: Since the first filter layer 30 only transmits light with wavelengths below 490nm, the blue light BL0 (400nm-500nm) is transmitted as blue light BL02 (400nm-490nm) after passing through the first filter layer 30; after being excited by the blue light BL02 (400nm-490nm), the blue quantum dot emits blue light BL0 (400nm-500nm), which propagates to the second filter layer 40; since the second filter layer 40 can only transmit light with wavelengths between 450nm and 700nm, the blue light BL0 (400nm-500nm) with wavelengths below 450nm... Blue light BL01 between 00nm and 450nm will be reflected back to the blue quantum dot by the second filter layer 40 and re-excited, causing the blue quantum dot to emit blue light BL1 (400nm-500nm) again; and the blue light BL01 with a wavelength between 400nm and 450nm in the blue light BL1 (400nm-500nm) will be reflected again by the second filter layer 40, so that the light transmitted from the second filter layer 40 is BL0 (400nm-500nm) + BL1 (400nm-500nm) - BL0 (400nm-450nm), that is, it does not include harmful blue light BL01 with a wavelength between 400nm and 450nm. In simple terms, harmful blue light BL01 with wavelengths between 400nm and 450nm is confined to the incident light side of the second filter layer 40 and is reflected multiple times to the third color conversion unit 203 for multiple excitations; only blue light with wavelengths greater than 450nm can be transmitted through the second filter layer 40.

[0075] As can be seen, in the above example, by placing the light-incident surface and the light-exit surface of the blue quantum dot opposite to the first filter layer 30 and the second filter layer 40, in addition to the beneficial effects that can be produced in the above embodiment 1, it also has the following effects: the harmful blue light BL01 with a wavelength between 400nm and 450nm is confined to the light-incident side of the second filter layer 40 and is reflected multiple times to the third color conversion unit 203 to participate in excitation multiple times. On the one hand, it can reduce the harmful blue light in the light emitted by the backlight module 1 and avoid affecting the health of users; on the other hand, it can increase the excitation energy of the color conversion layer 20, thereby improving the luminous efficiency of the color conversion unit.

[0076] In summary, the backlight module 1 provided in Embodiment 1 of this disclosure has at least the following beneficial effects: 1. It increases the excitation energy of each color conversion unit in the color conversion layer 20, thereby improving the luminous efficiency of the color conversion unit; 2. It reduces the blue light and harmful blue light doped in the red and green light emitted by the backlight module 1, thereby improving the purity of the light.

[0077] Example 2:

[0078] Figure 11 is an exploded view of the backlight module 1 in Embodiment 2. As shown in Figure 11, the backlight module 1 includes a light-emitting substrate 11, a color conversion layer 20, a first filter layer 30, and a second filter layer 40. The light-emitting substrate 11 is configured to emit blue light, at least a portion of which is light of a first preset wavelength band. The color conversion layer 20 is disposed on the light-emitting side of the light-emitting substrate 11 and includes multiple color conversion units, including a first color conversion unit 201, a second color conversion unit 202, and a third color conversion unit 203, which are respectively red quantum dots, green quantum dots, and blue quantum dots. The first filter layer 30 includes a first filter portion 301 and a first light-transmitting portion 302, and the second filter layer 40 includes a second filter portion 401 and a second light-transmitting portion 402. In this embodiment, the light-incident surfaces of both the red and green quantum dots are opposite to the first light-transmitting portion 302, and the light-exiting surfaces are opposite to the second light-transmitting portion 402; the light-incident surface of the blue quantum dots is opposite to the first filter portion 301, and the light-exiting surface is opposite to the second filter portion 401. Furthermore, the maximum value in the first preset wavelength band is 490nm; the second preset wavelength band is 450nm-490nm.

[0079] Figure 12 is an optical path diagram of the light after passing through each film layer in the backlight module 1 shown in Figure 11. As shown in Figure 12, the light emitted directly by the light-emitting substrate 11 is blue light BL0, and its wavelength is in the range of 400nm-500nm. When only the light-incident surface of the blue quantum dots faces the first filter 301 and the light-emitting surface faces the second filter 401, the blue light BL0 directly emitted by the light-emitting substrate 11 undergoes approximately the following process at the blue quantum dot region: Since the first filter layer 30 can only transmit light with wavelengths below 490nm, the blue light BL0 (400nm-500nm) after passing through the first filter layer 30 becomes blue light BL02 with a wavelength between 400nm and 490nm; when the blue light BL02 (400nm-490nm) reaches the third color conversion unit 203, it is excited by the blue light BL02 (400nm-490nm) and emits blue light BL0 (400nm-500nm), which is then emitted by the second filter layer 401. The first filter layer 40 only transmits light with wavelengths in the 450nm-490nm range. Therefore, when blue light BL0 (400nm-500nm) reaches the second filter layer 40, the blue light BL01 with wavelengths in the 400nm-450nm range will be reflected back to the blue quantum dot by the first filter layer 40, exciting the blue quantum dot again, causing it to emit blue light BL1 again. The wavelength of this blue light BL1 is in the 400nm-500nm range. After it propagates to the first filter layer 30, some of the light with wavelengths in the 490nm-500nm range is reflected back to the blue quantum dot. Finally, the light transmitted through the second filter layer 40 is BL0+BL1-BL01, which does not include harmful blue light with wavelengths in the 400nm-450nm range.

[0080] In simple terms, harmful blue light BL01 with wavelengths between 400nm and 450nm is confined to the incident light side of the second filter layer 40 and is reflected multiple times to the blue quantum dots for excitation; only blue light with wavelengths between 450nm and 490nm can be transmitted through the second filter layer 40.

[0081] As can be seen from the optical path diagram shown in Figure 12, the backlight module 1 shown in Embodiment 2 can produce at least one of the following beneficial effects compared with the prior art: 1. By setting a second filter layer 40 on the light-emitting side of the color conversion layer 20, and setting the second filter layer 40 to only transmit light with wavelengths between 450nm and 490nm, harmful blue light in the emitted light can be filtered out on the one hand; on the other hand, the harmful blue light is restricted to being reflected multiple times on the light-incident side of the second filter layer 40, thereby participating in the excitation of blue quantum dots multiple times, which can effectively improve the excitation energy and light-emitting efficiency of blue quantum dots; 2. By setting a first filter layer 30 on the light-incident side of the color conversion layer 20, and setting the first filter layer 40 to only transmit light with wavelengths below 490nm, the light emitted by the blue quantum dots in the BL1 (400nm-500nm) range with wavelengths between 490nm and 500nm can be reflected to the blue quantum dots to participate in the excitation again, which can further improve the excitation energy and light-emitting efficiency of blue quantum dots.

[0082] In some examples, the size of the quantum dots can be 1 nm to 20 nm, and the specific size can be set according to the desired color of the emitted light; the thickness of the color conversion layer 20 can be between 2 μm and 15 μm. The materials of the quantum dots can include silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, indium phosphide quantum dots, and indium arsenide quantum dots, etc., which can be determined according to actual needs. Figure 13 shows the excitation spectrum of the color conversion layer 20 of this disclosure.

[0083] In some examples, the first filter layer 30 and / or the second filter layer 40 can be Bragg reflectors. A Bragg reflector, also known as a Bragg film, is a multilayer film structure composed of periodically alternating stacked high-refractive-index and low-refractive-index materials. Exemplarily, the materials of the first filter layer 30 and the second filter layer 40 used in this disclosure include silicon dioxide (Si₂O) and titanium dioxide (Ti₂O). By adjusting the thickness and number of different material layers in the Bragg reflector, the first filter layer 30 and the second filter layer 40 that transmit specific wavelengths of light as described in Embodiment 1 or Embodiment 2 can be obtained. For example, the first filter layer 30 is a short-pass filter (SPF), with a transmittance band below 490 nm; the second filter layer 40 in Example 1 is a first long-pass filter (LPF), with a transmittance band between 450 nm and 700 nm; the second filter layer 40 in Example 2 is a second long-pass filter, with a transmittance band between 450 nm and 490 nm. Figure 14 shows the transmission spectra of the short-pass filter SPF, the first long-pass filter LPF1, and the second long-pass filter LPF2. During fabrication, each film layer can be deposited sequentially using a deposition process to form the first filter layer 30 and the second filter layer 40 that meet the transmission conditions.

[0084] Furthermore, in some examples, the backlight module 1 provided in this disclosure also includes a light guide plate 60 opposite to the light-emitting surface of the light-emitting substrate 11, and a barrier layer 70 disposed on the side of the color conversion layer 20 away from the light-emitting substrate 11. Figure 15 is an exploded view of the structure of the backlight module 1 including the light guide plate 60 and the barrier layer 70. As shown in Figure 14, the light guide plate 60 is used to uniformly distribute the light emitted by the light-emitting substrate 11 across the entire display surface, ensuring consistent brightness across the entire display surface; the first filter film layer 30 is disposed on the side of the light guide plate 60 away from the light-emitting substrate 11. The barrier layer 70 is used to protect the quantum dot light-emitting layer in the color conversion layer 20, preventing external water and oxygen from entering and affecting its light-emitting performance. For example, the barrier layer 70 can be made of inorganic materials such as silicon nitride and silicon oxide that isolate water and oxygen.

[0085] Furthermore, still referring to Figure 15, the color conversion layer 20 has a spacing portion 50 between two adjacent color conversion units to separate color conversion units of different colors. The spacing portion 50 can be made of organic insulating material, such as photoresist or other organic materials.

[0086] Those skilled in the art will understand that the backlight module 1 provided in this disclosure also includes a back plate and a driving circuit disposed on the back plate for driving the light-emitting substrate 11; of course, it may also include other optical film layers such as brightness enhancement film and diffuser film, which are not limited here.

[0087] Secondly, this disclosure provides a display device including a backlight module 1 provided in any embodiment of the first aspect. FIG16 is an exploded view of the structure of the display device provided in this disclosure. As shown in FIG16, the display device includes a backlight module 1 and a display panel 2, wherein the backlight module 1 is disposed on the light-incident side of the display panel 2 to provide a backlight source required by the display panel 2. The display panel 2 includes a first substrate 21 and a second substrate 22 disposed opposite to each other, and a liquid crystal layer 23 located between the first substrate 21 and the second substrate 22; wherein the first substrate 21 may be an array substrate, and the second substrate 22 may be a color filter substrate. The display panel 2 further includes a first polarizer 3 disposed on the side of the first substrate 21 opposite to the liquid crystal layer 23, and a second polarizer 4 disposed on the side of the second substrate 22 opposite to the liquid crystal layer 23. It is understood that when the first substrate 21 is an array substrate and the second substrate 22 is a color filter substrate, the array substrate may include a first substrate and a pixel electrode formed on the side of the first substrate near the liquid crystal layer 23, and the color filter substrate may include the second substrate and a common electrode formed on the side of the second substrate near the liquid crystal layer 23; of course, the pixel electrode and the common electrode may also be disposed on the first substrate, and this disclosure does not limit this.

[0088] Because of the use of the backlight module 1 shown in the above embodiments, the display device provided by this disclosure has advantages over existing display devices, such as vivid colors, reduced harmful blue light, high luminous efficiency, and low power consumption.

[0089] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A backlight module, comprising: A light-emitting substrate is configured to emit light of a first color, at least a portion of which is light of a first preset wavelength. A color conversion layer is disposed on the light-emitting side of the light-emitting substrate; the color conversion layer includes a plurality of color conversion units; each color conversion unit is configured to emit light of a corresponding color when excited by a first color light; at least a portion of the light emitted by the color conversion layer is light of a second preset wavelength band; the plurality of color conversion units includes a first color conversion unit and a second color conversion unit; the first color conversion unit is configured to emit light of a second color when excited by the first color light; the second color conversion unit is configured to emit light of a third color when excited by the first color light; wherein, the backlight module further includes a first filter film layer disposed between the light-emitting substrate and the color conversion layer, and a second filter film layer disposed on the side of the color conversion layer away from the light-emitting substrate; at least a portion of the light-incident surfaces of the color conversion units face the first filter film layer, and the light-emitting surfaces face the second filter film layer; the first filter film layer is configured to transmit light of the first preset wavelength band; the second filter film layer is configured to transmit light of the first preset wavelength band. The color conversion layer further includes a transmission unit for transmitting the first color light; the light-incident surface of the transmission unit is opposite to the first filter layer, and the light-exiting surface is opposite to the second filter layer; or, the plurality of color conversion units further includes a third color conversion unit; the third color conversion unit is configured to emit light of the first color under the excitation of the first color light; the light-incident surface of the third color conversion unit is opposite to the first filter layer, and the light-exiting surface is opposite to the second filter layer; the first color is blue, the second color is red, and the third color is green; the maximum value in the first preset wavelength band is 490nm; the second preset wavelength band is 450nm-700nm; the first filter layer and / or the second filter layer includes silicon dioxide and titanium dioxide; the backlight module further includes: a barrier layer disposed on the side of the color conversion layer away from the light-emitting substrate; the second filter layer is disposed on the side of the barrier layer away from the light-emitting substrate; the material of the barrier layer includes silicon nitride or silicon oxide.

2. The backlight module according to claim 1, wherein, The light-incident surfaces of both the first color conversion unit and the second color conversion unit are opposite to the first filter layer, and the light-outceasing surfaces are opposite to the second filter layer.

3. The backlight module according to claim 1, wherein, The first filter film layer includes a first filter portion and a first light-transmitting portion, and the second filter film layer includes a second filter portion and a second light-transmitting portion; the light-incident surfaces of the first color conversion unit and the second color conversion unit are both opposite to the first light-transmitting portion, and the light-exiting surfaces of both are opposite to the second light-transmitting portion; the light-incident surface of the third color conversion unit is opposite to the first filter portion, and the light-exiting surface is opposite to the second filter portion.

4. The backlight module according to claim 3, wherein, The first color is blue, the second color is red, and the third color is green; the maximum value in the first preset wavelength band is 490nm; the second preset wavelength band is 450nm-490nm.

5. The backlight module according to any one of claims 1-4, wherein, The color conversion unit includes a quantum dot light-emitting layer.

6. The backlight module according to any one of claims 1-4, wherein, There is a gap between two adjacent color conversion units.

7. The backlight module according to claim 6, wherein, The spacer portion includes an organic insulating material.

8. The backlight module according to any one of claims 1-4, wherein, Also includes: A light guide plate opposite to the light-emitting surface of the light-emitting substrate; The first filter film layer is disposed on the side of the light guide plate away from the light-emitting substrate.

9. A display device comprising a backlight module as described in any one of claims 1-8.

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