CN105242457A - Light guide device with high color saturation - Google Patents

Abstract

The invention provides a light guide device with high color saturation, which comprises: a blue LED light source; the first light guide plate is used for transmitting the light emitted by the blue LED light source to the opposite side far away from the light source; the second light guide plate is arranged above the first light guide plate; the quantum dot film layer is arranged on one side, far away from the blue LED light source, of the second light guide plate and used for converting blue light on the light outlet end face of the first light guide plate into white light; and a first reflector plate. Compared with the prior art, the LED light source structure adopts the structural design of double light guide plates, blue light is transmitted to the other side far away from the LED light source through the first light guide plate and is incident to the quantum dot thin film layer on the side face of the second light guide plate from the light-emitting end face of the first light guide plate, and the blue light is converted into white light by the quantum dot thin film layer and then is guided into the second light guide plate, so that the light is uniformly emitted in the whole face. Therefore, the invention can further reduce the use area of the quantum dot film layer, thereby reducing the cost.

Description

A light guide device with high color saturation

technical field

The invention relates to a backlight module, in particular to a light guide device with high color saturation.

Background technique

In recent years, with the vigorous development of consumer electronics, the market demand for display devices of various sizes is increasing. Among them, Liquid Crystal Display (LCD) has the advantages of light weight, thin body, low power consumption, and no radiation. It is widely used in consumer electronics or computer products such as portable TVs, mobile phones, video recorders, notebook computers, and desktop displays, and has become the mainstream of displays. Liquid crystal is a passive light-emitting device that requires light from a backlight source to display image content. Common backlight sources include cold cathode tubes (Cold Cathode Fluorescent Lamp, CCFL) and light emitting diodes (Light Emitting Diode, LED). Among them, LED is rapidly replacing CCFL as the mainstream technology of backlight with its advantages of high lumen efficiency, high color rendering ability, low-voltage drive, no fragile parts, and no heavy metal materials. Since the liquid crystal panel itself does not emit light, images must be displayed through the backlight provided by the backlight module, so the backlight module has become one of the key components of the liquid crystal display device. Generally speaking, the backlight module can be divided into two types, the side-type backlight module and the direct-type backlight module, according to the incident position of the light source. For example, the direct-type backlight module sets the light source behind the liquid crystal panel to directly form a surface light source for the liquid crystal panel; while the side-type backlight module sets the backlight LED light bar (Lightbar) behind the side of the liquid crystal panel. At the edge of the back panel, the light emitted by the LED light bar enters the light guide plate from the light incident surface on one side of the light guide plate (LGP), and is emitted from the light exit surface of the light guide plate after reflection and diffusion, and then generates a surface light source through the optical film group to provide to the LCD panel.

Solid-state lighting, on the other hand, includes two typical architectures: one that combines red, green, and blue LEDs; and one that combines UV LED chips or blue LED chips with color-converting phosphors. Taking the latter as an example, a light conversion layer containing a color conversion phosphor often requires a high photoluminescence quantum efficiency, a suitable refractive index, good light fastness and the required luminous color. Here, quantum dot (QuantumDot, QD) is a light-emitting semiconductor crystal, which has a narrow and tunable photoluminescence spectrum, high photoluminescence quantum efficiency, and inherent thermal stability of inorganic materials. In addition, quantum dots can also effectively It converts blue light into highly saturated white light to display colors with the widest color gamut on the screen.

In the prior art, when quantum dots are applied to the structural design of backlight modules, they are usually divided into three types: quantum dot film (QDfilm), quantum dot tube (QDtube) and quantum dot light emitting diode (QDLED). Because the efficiency of quantum dots is closely related to life and temperature, and quantum dot tubes and quantum dot light-emitting diodes will be affected by temperature and suffer from heat exhaustion, which will reduce the overall luminous efficiency. The location of the diaphragm, together with the brightness enhancement film and two prism sheets, can make the overall luminous efficiency reach 85% of the LED luminance of ordinary phosphor powder. However, the current quantum dot film layer uses too much area, and the cost is relatively high.

In view of this, how to design a new backlight module architecture, which can not only take advantage of the high photoluminescence quantum efficiency of quantum dots, but also reduce its use area and cost, so as to overcome the above-mentioned defects or deficiencies in the prior art, is an important issue. It is a problem to be solved urgently by relevant technicians in the industry.

Contents of the invention

Aiming at the above defects in the prior art backlight module with quantum dot film layer, the present invention provides a novel light guide device with high color saturation.

According to one aspect of the present invention, a light guide device with high color saturation is provided, comprising:

A blue LED light source;

A first light guide plate, arranged on the side of the blue LED light source, the first light guide plate is used to transmit the light emitted by the blue LED light source to the opposite side away from the blue LED light source;

A second light guide plate, arranged above the first light guide plate;

A quantum dot thin film layer, arranged on the side of the second light guide plate away from the blue LED light source, the quantum dot thin film layer is used to transfer the blue light from the light-emitting end surface of the first light guide plate converted to white light; and

A first reflection sheet, located below the first light guide plate, is used to reflect part of the blue light emitted by the first light guide plate back to the inside of the first light guide plate.

In one of the embodiments, part of the blue light emitted by the first light guide plate is reflected by the surface of the quantum dot film layer, and another part of the blue light is converted into red light and green light by the quantum dot film layer , the quantum dot film layer is used for mixing the reflected blue light, the converted red light and the green light to generate the white light.

In one embodiment, the first light guide plate or the second light guide plate is formed by splicing a plurality of pieces.

In one of the embodiments, the light guide device further includes a second reflective sheet, which is arranged on the side of the quantum dot thin film layer away from the second light guide plate, and the second reflective sheet is used to Part of the red light, part of the green light and part of the blue light passing through the quantum dot film layer are reflected back to reduce light energy loss.

In one of the embodiments, the light guide device further includes a third reflective sheet located above the second light guide plate, the third reflective sheet has a plurality of through holes distributed at intervals, and through the through holes The holes return the blue light emitted by the second light guide plate back to the quantum dot film layer.

In one embodiment, the light emitting end surface of the first light guide plate is an inclined surface, the inclined surface faces the second light guide plate, and the inclination angle is between 20 degrees and 45 degrees.

In one of the embodiments, the longest distance from the light exit end surface of the first light guide plate to the quantum dot film layer is less than the product of the height of the second light guide plate and tanθ1, where _θ1 is the _first The critical angle of total reflection of the light guide plate.

In one embodiment, the light-emitting end surface of the first light guide plate is a triangular groove or a rounded groove.

In one embodiment, the first light guide plate and the second light guide plate are polyethylene terephthalate (PET), polycarbonate (PC) or polymethyl methacrylate (PMMA). material.

In one embodiment, the light guiding device is used as a side-entry backlight module or a direct-down backlight source.

The light guide device with high color saturation of the present invention includes a blue LED light source, a first light guide plate, a second light guide plate, a quantum dot film layer and a first reflection sheet, and the first light guide plate is arranged on the blue LED The side of the light source is used to transmit the light emitted by the blue LED light source to the opposite side away from the blue LED light source. The second light guide plate is arranged above the first light guide plate, and the quantum dot film layer is arranged on the second light guide plate. On the side away from the blue LED light source, the quantum dot film layer converts the blue light from the light-emitting end surface of the first light guide plate into white light, and the first reflector is located under the first light guide plate to reflect part of the blue light Back to the inside of the first light guide plate. Compared with the prior art, the present invention adopts the architecture design of double light guide plates, and transmits the blue light to the other side away from the LED light source through the first light guide plate, and enters the second light guide plate from the light-emitting end surface of the first light guide plate. The quantum dot film layer on the side of the light plate converts the blue light into white light through the quantum dot film layer and then guides it into the second light guide plate, so that the light is evenly emitted from the entire surface. In this way, the present invention arranges the quantum dot thin film layer on the side away from the LED light source, which can further reduce the use area of the quantum dot thin film layer, thereby reducing the cost.

Description of drawings

Readers will have a clearer understanding of various aspects of the present invention after reading the detailed description of the present invention with reference to the accompanying drawings. in,

Fig. 1 shows a schematic structural view of a backlight module with a quantum dot film layer in the prior art;

FIG. 2 shows a schematic structural view of a light guide device with high color saturation according to an embodiment of the present invention;

Fig. 3 A shows a first embodiment of the light guiding device shown in Fig. 2;

Figure 3B shows a second embodiment of the light guiding device shown in Figure 2;

Fig. 3 C shows a third embodiment of the light guiding device shown in Fig. 2;

Figure 3D shows a fourth embodiment of the light guiding device shown in Figure 2;

Figure 3E shows a fifth embodiment of the light guiding device shown in Figure 2;

FIG. 3F shows a sixth embodiment of the light guiding device shown in FIG. 2;

Fig. 4 shows a schematic structural diagram of a first light guide plate with a better light energy ratio in the light guide device of Fig. 2;

FIG. 5 shows a schematic structural view of a liquid crystal display device using the light guide device of FIG. 2 according to another embodiment of the present invention; and

FIG. 6 shows a schematic structural diagram of a liquid crystal display device using the light guide device of FIG. 2 according to yet another embodiment of the present invention.

detailed description

In order to make the technical content disclosed in this application more detailed and complete, reference may be made to the drawings and the following various specific embodiments of the present invention, and the same symbols in the drawings represent the same or similar components. However, those skilled in the art should understand that the examples provided below are not intended to limit the scope of the present invention. In addition, the drawings are only for schematic illustration and are not drawn according to their original scale.

The specific implementation manners of various aspects of the present invention will be further described in detail below with reference to the accompanying drawings.

FIG. 1 shows a schematic structural view of a backlight module with a quantum dot film layer in the prior art.

1, the existing backlight module includes a blue LED light source 101, a quantum dot film layer (QuantumDotFilm) 103, a light guide plate (LightGuidePlate, LGP) 105, a quantum dot reflective layer 107 and reflective sheet (ReflectiveSheet) 109 and reflector 111.

Wherein, the quantum dot film layer 103 is disposed between the blue LED light source 101 and the light guide plate 105 . The quantum dot film layer 103 is used to transmit a part of the blue light emitted by the light source 101 and convert another part of the blue light into red light and green light. As shown in FIG. 1 , blue light is represented by thick lines L1 , and red light and green light are represented by thin lines L2 . The reflective sheet 109 is arranged under the light guide plate 105, and the reflective sheet 111 is arranged on the side of the light guide plate 105 away from the blue LED light source, and they reflect the light emitted from the lower side and the right side of the light guide plate 105 back to the inside of the light guide plate 105 , to reduce light energy loss. As we know, the top of the light guide plate 105 is a light-emitting end surface, and the emitted light is reflected and converted by the quantum dot reflector 107 to generate uniformly mixed white light.

However, as mentioned in the background section, quantum dot films are susceptible to thermal exhaustion due to temperature. In FIG. 1 , the quantum dot film layer 103 is too close to the blue LED light source 101 , and the heat exhaustion is serious. Moreover, the quantum dot film layer 103 will also reflect part of the light back to the blue LED light source 101, which not only causes energy loss, but also aggravates the heat exhaustion effect. In addition, the quantum dot reflective layer 107 disposed above the light guide plate 105 is a reflective layer made of a whole piece of material, and the use area is too large and the cost is expensive.

In order to solve the above defects or deficiencies in the prior art, the present invention discloses a novel light guide device with high color saturation. Wherein, FIG. 2 shows a schematic structural diagram of a light guide device with high color saturation according to an embodiment of the present invention. In the following description, unless otherwise specified, the blue light is represented by a thick line L1, and the red light and green light are represented by a thin line L2.

Referring to FIG. 2 , in this embodiment, the light guide device of the present invention adopts a stacked design of double light guide plates. Specifically, the light guide device includes a blue LED light source 201 , a first light guide plate (firstLGP) 203 , a second light guide plate (secondLGP) 205 , a quantum dot film layer 207 and a first reflection sheet 209 . Preferably, the light guide device can be used as a side-lit backlight module, or the light guide device can be used as a direct-down backlight source.

In detail, the first light guide plate 203 is disposed on the side of the blue LED light source 201 . The first light guide plate 203 is used to guide the blue light L1 emitted by the blue LED light source 201 to an opposite side away from the blue LED light source 201 . The second light guide plate 205 is disposed above the first light guide plate 203 , for example, the light-emitting end surface of the first light guide plate 203 is opposite to the light-incoming end surface of the second light guide plate 205 . The quantum dot film layer 207 is disposed on a side of the second light guide plate 205 away from the blue LED light source 201 . In this way, the quantum dot film layer 207 can convert the blue light from the light-emitting end surface of the first light guide plate 203 into white light. The first reflection sheet 209 is located below the first light guide plate 203 and is used for reflecting part of the blue light emitted by the first light guide plate 203 from below back to the inside of the first light guide plate 203 . In addition, another smaller quantum dot thin film layer 211 can be installed above the first reflection sheet 209 and close to the light-emitting end surface of the first light guide plate 203 to increase the utilization efficiency of light energy.

In a specific embodiment, part of the blue light emitted from the first light guide plate 203 is reflected by the surface of the quantum dot film layer 207 , and another part of the blue light is converted into red light and green light by the quantum dot film layer 207 . The quantum dot film layer 207 is used to mix the reflected blue light, converted red light and green light to generate white light.

In a specific embodiment, the first light guide plate and the second light guide plate can be made of polyethylene terephthalate (PET), polycarbonate (PC) or polymethyl methacrylate (PMMA).

From the above, it can be known that the present invention transmits the blue light to the other side away from the blue LED light source through the first light guide plate, and enters the quantum dot film layer on the side of the second light guide plate from the light-emitting end surface of the first light guide plate. The blue light is converted into white light by the quantum dot film layer and then guided into the second light guide plate, so that the light can be evenly emitted from the entire surface. Since the quantum dot film layer is arranged on the side of the first light guide plate away from the LED light source, serious problems such as heat exhaustion in the prior art will not occur, and the use area of the quantum dot film layer can also be reduced, thereby reducing costs .

3A to 3F respectively illustrate several different embodiments of the light guiding device as shown in FIG. 2 .

As shown in FIG. 3A , in this embodiment, the main difference from the light guide device in FIG. 2 is that the blue LED light source 301 uses a higher power LED. This is because, although the power of the LED is greater, the temperature rise is higher, but the quantum dot thin film layer 207 is placed on the right side of the first light guide plate 203, and the distance between it and the LED light source is far, and it is greatly affected by the temperature. Small. In FIG. 3B , the second light guide plate 205 is formed by splicing multiple pieces. Of course, in other embodiments, multiple pieces of the first light guide plate 203 may also be spliced.

Referring to Figure 3C and Figure 3D, and comparing them with Figure 2, the main difference is that the light-emitting end face of the first light guide plate is specially designed so that the outgoing blue light is incident on the incident end face of the second light guide plate underside. For example, the light emitting end surface of the first light guide plate 203 in FIG. 3C is designed as a triangular groove S1. As another example, the light emitting end surface of the first light guide plate 203 in FIG. 3D is designed as a rounded groove S2. In addition, experimental data testing shows that the angles θ ₃₁ and θ ₃₂ of light incident on the light-emitting surface of the second light guide plate are both greater than 40 degrees.

As shown in FIG. 3E , in this embodiment, the light guide device further includes a second reflective sheet 213 disposed on the side of the quantum dot film layer 207 away from the second light guide plate 205 . The second reflective sheet 213 is used to reflect back part of the red light, part of the green light and part of the blue light passing through the quantum dot thin film layer 207 so as to reduce light energy loss.

As shown in FIG. 3F , in this embodiment, the light guide device is not only provided with a second reflective sheet 213, but also provided with a third reflective sheet 215 above the second light guide plate 205 and below the first light guide plate 203. Quantum dot film layer 211a. Wherein, the third reflection sheet 215 also has a plurality of through holes 217 distributed at intervals, and through these through holes 217, the blue light emitted by the second light guide plate 205 is returned to the quantum dot film layer 211a, which can not only further increase the luminous efficiency , but also to adjust the light uniformity.

FIG. 4 shows a schematic structural view of the first light guide plate when there is a better light energy ratio in the light guide device in FIG. 2 .

Referring to FIG. 4, in this embodiment, the thickness of the first light guide plate 203 is H1, and the thickness of the second light guide plate 205 is H2. After the blue light emitted by the blue LED light source 201 enters the first light guide plate 203 , its incident angle and reflection angle are both θ ₁ . The light emitting end surface of the first light guide plate 203 is an inclined surface, and the included angle between the inclined surface and the horizontal plane is θ ₂ . The angle of light incident on the light-emitting surface of the second light guide plate 205 is denoted as θ ₃₃ . Experiments have shown that when θ ₂ is 90 degrees, the ratio of light energy on the light-emitting surface of the second light guide plate 205 to the blue LED light source is 0; when θ ₂ is 45 degrees, the light energy on the light-emitting surface of the second light guide plate 205 The proportion of energy relative to the blue LED light source is 58%; when θ2 is 30 degrees, the proportion of light energy of the light emitting surface of the _second light guide plate 205 relative to the blue LED light source is 88%. Generally, the inclination angle θ ₂ can be selected to be between 20 degrees and 45 degrees.

In a specific embodiment, in order to prevent blue light from successfully entering the quantum dot film layer and causing light leakage in the picture, the longest distance from the light-emitting end surface of the first light guide plate 203 to the quantum dot film layer 207 should be less than the height H2 of the second light guide plate 205 The product of tanθ ₁ , where θ ₁ is the critical angle of total reflection of the first light guide plate. Similarly, the angle θ ₃₃ of the light incident on the light-emitting surface of the second light guide plate 205 is greater than 40 degrees.

FIG. 5 shows a schematic structural diagram of a liquid crystal display device using the light guide device in FIG. 2 according to another embodiment of the present invention.

Referring to FIG. 5 , in this embodiment, the liquid crystal display device includes a liquid crystal panel 305 , an optical film layer 303 and a light guide device. The optical film layer 303 is located under the liquid crystal panel 305 , and the light guide device is located under the optical film layer 303 . As mentioned above, the light-emitting surface of the second light-guiding plate 205 in the light-guiding device can emit uniform white light to meet the backlight requirements required by the liquid crystal molecules in the liquid crystal panel.

FIG. 6 shows a schematic structural diagram of a liquid crystal display device using the light guide device of FIG. 2 according to yet another embodiment of the present invention.

Referring to FIG. 6 , similar to FIG. 5 , in this embodiment, the liquid crystal display device includes a liquid crystal panel 305 , an optical film layer 303 , a diffuser plate 307 and a light guide device. The optical film layer 303 is located below the liquid crystal panel 305 , and the diffusion plate 307 is located below the optical film layer 303 . The light guiding device is located under the diffuser plate 307 . The difference from FIG. 5 is that a third reflective sheet 217 is disposed above the second light guide plate. The third reflection sheet 215 also has a plurality of through holes 217 distributed at intervals, and through these through holes 217, part of the blue light emitted by the second light guide plate is returned to the bottom edge of the quantum dot film layer 207a, which not only increases the light emission efficiency, light uniformity can also be adjusted.

The light guide device with high color saturation of the present invention includes a blue LED light source, a first light guide plate, a second light guide plate, a quantum dot film layer and a first reflection sheet, and the first light guide plate is arranged on the blue LED The side of the light source is used to transmit the light emitted by the blue LED light source to the opposite side away from the blue LED light source. The second light guide plate is arranged above the first light guide plate, and the quantum dot film layer is arranged on the second light guide plate. On the side away from the blue LED light source, the quantum dot film layer converts the blue light from the light-emitting end surface of the first light guide plate into white light, and the first reflector is located under the first light guide plate to reflect part of the blue light Back to the inside of the first light guide plate. Compared with the prior art, the present invention adopts the architecture design of double light guide plates, and transmits the blue light to the other side away from the LED light source through the first light guide plate, and enters the second light guide plate from the light-emitting end surface of the first light guide plate. The quantum dot film layer on the side of the light plate converts the blue light into white light through the quantum dot film layer and then guides it into the second light guide plate, so that the light is evenly emitted from the entire surface. In this way, the present invention arranges the quantum dot thin film layer on the side away from the LED light source, which can further reduce the use area of the quantum dot thin film layer, thereby reducing the cost.

Hereinbefore, specific embodiments of the present invention have been described with reference to the accompanying drawings. However, those skilled in the art can understand that without departing from the spirit and scope of the present invention, various changes and substitutions can be made to the specific embodiments of the present invention. These changes and substitutions all fall within the scope defined by the claims of the present invention.

Claims (10)

1. A light guide device with high color saturation, characterized in that the light guide device comprises: A blue LED light source; A first light guide plate, arranged on the side of the blue LED light source, the first light guide plate is used to transmit the light emitted by the blue LED light source to the opposite side away from the blue LED light source; A second light guide plate, arranged above the first light guide plate; A quantum dot thin film layer, arranged on the side of the second light guide plate away from the blue LED light source, the quantum dot thin film layer is used to transfer the blue light from the light-emitting end surface of the first light guide plate converted to white light; and A first reflection sheet, located below the first light guide plate, is used to reflect part of the blue light emitted by the first light guide plate back to the inside of the first light guide plate. 2. The light guide device with high color saturation according to claim 1, wherein a part of the blue light emitted by the first light guide plate is reflected by the surface of the quantum dot film layer, and another part of the blue light The quantum dot film layer is converted into red light and green light, and the quantum dot film layer is used to mix the reflected blue light, the converted red light and the green light to generate the white light. 3 . The light guide device with high color saturation according to claim 1 , wherein the first light guide plate or the second light guide plate is formed by splicing a plurality of pieces. 4. The light guide device with high color saturation according to claim 1, characterized in that, the light guide device further comprises a second reflection sheet, which is arranged on the quantum dot thin film layer, away from the second On one side of the light guide plate, the second reflective sheet is used to reflect back part of the red light, part of the green light and part of the blue light that pass through the quantum dot film layer so as to reduce light energy loss. 5. The light guide device with high color saturation according to claim 1, characterized in that, the light guide device further comprises a third reflective sheet located above the second light guide plate, and the third reflector The sheet has a plurality of through holes distributed at intervals, through which the blue light emitted by the second light guide plate is returned to the quantum dot thin film layer. 6. The light guide device with high color saturation according to claim 1, wherein the light-emitting end surface of the first light guide plate is an inclined plane, the inclined plane faces the second light guide plate, and the inclination angle is between Between 20 degrees and 45 degrees. 7. The light guide device with high color saturation according to claim 6, characterized in that the longest distance from the light exit end surface of the first light guide plate to the quantum dot thin film layer is smaller than that of the second light guide plate. The product of the height and tanθ ₁ , wherein θ ₁ is the critical angle of total reflection of the first light guide plate. 8 . The light guide device with high color saturation according to claim 6 , wherein the light emitting end surface of the first light guide plate is a triangular groove or a rounded groove. 9. The light guide device with high color saturation according to claim 1, characterized in that, the first light guide plate and the second light guide plate are made of polyethylene terephthalate, polycarbonate or Made of polymethylmethacrylate. 10 . The light guide device with high color saturation according to claim 1 , wherein the light guide device is used as a side-entry backlight module or a direct-down backlight source. 11 .