A display device

Abstract

An embodiment of the present invention discloses a display device. In one specific embodiment, the device includes a display panel and a light-shielding layer, a cholesteric liquid crystal film, a quarter-wave plate, and a polarizer sequentially arranged on the light-emitting side of the display panel. The display panel includes a substrate and red sub-pixels, green sub-pixels, and blue sub-pixels arranged in an array on the substrate. The cholesteric liquid crystal film is used to transmit one of left-handed circularly polarized light and right-handed circularly polarized light in light of a set wavelength band belonging to the blue light band, and reflect the other. The angle between the slow axis of the quarter-wave plate and the absorption axis of the polarizer is set so that the polarizer transmits the circularly polarized light passing through the quarter-wave plate. The light-shielding layer is provided with a first opening corresponding to the red sub-pixel, a second opening corresponding to the green sub-pixel, and a third opening corresponding to the blue sub-pixel. This embodiment can reduce the display panel's reflection of ambient light while ensuring the effect of improving the light-emitting efficiency of the display panel, thereby improving the color shift caused by the display panel's reflection of blue light in the ambient light.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and more particularly to a display device. Background Art

[0002] Currently, it is difficult for existing display devices to simultaneously achieve good effects of reducing ambient light reflection and increasing light extraction efficiency. Summary of the Invention

[0003] An object of the present invention is to provide a display device to solve at least one of the problems existing in the prior art.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention provides a display device, characterized in that it includes a display panel and a light-shielding layer, a cholesteric liquid crystal film, a quarter-wave plate and a polarizer arranged in sequence on the light-emitting side of the display panel, the display panel including a substrate and red light sub-pixels, green light sub-pixels and blue light sub-pixels arranged in an array on the substrate, the cholesteric liquid crystal film is used to transmit one of left-handed circularly polarized light and right-handed circularly polarized light in light of a set wavelength band belonging to the blue light band, and reflect the other; the angle between the slow axis of the quarter-wave plate and the absorption axis of the polarizer is set so that the polarizer transmits the circularly polarized light passing through the quarter-wave plate; the light-shielding layer is provided with a first opening corresponding to the red light sub-pixel, a second opening corresponding to the green light sub-pixel and a third opening corresponding to the blue light sub-pixel.

[0006] Optionally, the display panel includes a pixel defining layer arranged on the substrate, the pixel defining layer having a red light pixel opening corresponding to the red light sub-pixel, a green light pixel opening corresponding to the green light sub-pixel, and a blue light pixel opening corresponding to the blue light sub-pixel, the orthographic projection of the first opening on the substrate covers the orthographic projection of the corresponding red light pixel opening on the substrate, the orthographic projection of the second opening on the substrate covers the orthographic projection of the corresponding green light pixel opening on the substrate, and the orthographic projection of the third opening on the substrate covers the orthographic projection of the corresponding blue light pixel opening on the substrate.

[0007] Optionally, the area of ​​the orthographic projection of the first opening on the substrate is larger than the area of ​​the orthographic projection of the corresponding red light pixel opening on the substrate, the area of ​​the orthographic projection of the second opening on the substrate is larger than the area of ​​the orthographic projection of the corresponding green light pixel opening on the substrate, and the area of ​​the orthographic projection of the third opening on the substrate is larger than the area of ​​the orthographic projection of the corresponding blue light pixel opening on the substrate.

[0008] Optionally, the ratio of the area of ​​the orthographic projection of the third opening on the substrate to the area of ​​the orthographic projection of the corresponding blue light pixel opening on the substrate is respectively greater than the ratio of the area of ​​the orthographic projection of the first opening on the substrate to the area of ​​the orthographic projection of the corresponding red light pixel opening on the substrate and the ratio of the area of ​​the orthographic projection of the second opening on the substrate to the area of ​​the orthographic projection of the corresponding green light pixel opening on the substrate.

[0009] Optionally, the set wavelength band is 430nm-490nm.

[0010] Optionally, the cholesteric liquid crystal film transmits one of left-handed circularly polarized light and right-handed circularly polarized light in light of a set wavelength band belonging to the blue light band and reflects the other by setting the pitch of liquid crystal molecules.

[0011] Optionally, the display device further includes a half-wave plate arranged between the quarter-wave plate and the polarizer.

[0012] Optionally, the quarter wave plate is a liquid crystal quarter wave plate, and / or the half wave plate is a liquid crystal half wave plate.

[0013] Optionally, the polarizer is a polyvinyl alcohol polarizer.

[0014] Optionally, the display device further comprises a cover plate arranged on a side of the polarizer away from the quarter-wave plate.

[0015] Optionally, the display panel is an organic light emitting diode display panel.

[0016] The beneficial effects of the present invention are as follows:

[0017] The technical solution of the present invention can reduce the reflection of ambient light by the display panel while ensuring the improvement of the light extraction efficiency of the display panel, and improve the color shift caused by the reflection of blue light in the ambient light by the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0019] Figure 1 A schematic structural diagram of an OLED display device provided with a circular polarizer is shown.

[0020] Figure 2 Show Figure 1 The diagram shows a light path diagram of the ambient light reflected by the OLED display device.

[0021] Figure 3 Show Figure 1Schematic diagram of the light path of the outgoing light from the OLED display device shown.

[0022] Figure 4 A schematic structural diagram of an OLED display device provided with a circular polarizer and a cholesteric liquid crystal film is shown.

[0023] Figure 5 Show Figure 4 Schematic diagram of the light path of the outgoing light from the OLED display device shown.

[0024] Figure 6 A schematic diagram showing the selection range of a set wavelength band characterized by the reflectivity of a cholesteric liquid crystal film to natural light.

[0025] Figure 7 A comparison diagram showing the gain effect of cholesteric liquid crystal films on the spectrum.

[0026] Figure 8 Show Figure 4 The diagram shows a light path of the OLED display device reflecting light of a predetermined wavelength band belonging to the blue light band in the ambient light.

[0027] Figure 9 A schematic structural diagram of an OLED display device provided with a circular polarizer, a cholesteric liquid crystal film and a light-shielding layer is shown. DETAILED DESCRIPTION

[0028] The terms “on…”, “formed on…” and “disposed on…” used in the present invention may mean that one layer is directly formed or disposed on another layer, or may mean that one layer is indirectly formed or disposed on another layer, i.e., there are other layers between the two layers.

[0029] It should be noted that although the terms "first," "second," etc. may be used herein to describe various parts, components, elements, regions, layers, and / or portions, these parts, components, elements, regions, layers, and / or portions should not be limited by these terms. Rather, these terms are used to distinguish one part, component, element, region, layer, and / or portion from another. Thus, for example, the first part, first member, first element, first region, first layer, and / or first portion discussed below may be referred to as a second part, second member, second element, second region, second layer, and / or second portion without departing from the teachings of the present invention.

[0030] In the present invention, unless otherwise specified, the term "co-layer arrangement" refers to two layers, components, members, elements, or parts that can be formed by the same manufacturing process (e.g., patterning process, etc.), and the two layers, components, members, elements, or parts are generally formed from the same material. For example, co-layer arrangement of two or more functional layers means that these co-layered functional layers can be formed using the same material layer and the same manufacturing process, thereby simplifying the manufacturing process of the display substrate.

[0031] In the present invention, unless otherwise specified, the expression "patterning process" generally includes the steps of photoresist coating, exposure, development, etching, photoresist stripping, etc. The expression "one-time patterning process" means a process of forming patterned layers, components, members, etc. using one mask.

[0032] For display panels such as organic light emitting diode (OLED) display panels, the metal layers of the display panels, such as the cathode (for example, the material is Mg-Ag magnesium silver alloy, with the ratio of Mg:Ag between 3:7 and 1:9) and anode of the OLED display panel, will cause strong ambient light reflection, resulting in a decrease in the contrast of display devices such as OLED display devices in environments with strong ambient light, such as outdoors on a sunny day, thereby affecting the user experience.

[0033] In order to solve the problem of ambient light reflection of existing OLED display devices, taking the OLED display device as an example, the first embodiment proposes an OLED display device provided with a circular polarizer, such as Figure 1 As shown, the OLED display device 100 provided with a circular polarizer proposed in the first embodiment includes an OLED display panel 110, a quarter-wave plate (or called a 1 / 4λ wave plate) 120 and a polarizer 130, wherein the quarter-wave plate 120 and the polarizer 130 constitute a circular polarizer. For example, the quarter-wave plate 120 is bonded and fixed to the light-emitting side of the OLED display panel 110 through an adhesive layer 191 such as a transparent optical adhesive (OCA), and the polarizer 130 is bonded and fixed to the side of the quarter-wave plate 120 away from the OLED display panel 110 through an adhesive layer 192 such as a transparent optical adhesive. For example, as Figure 1As shown, the OLED display panel 110 includes a substrate 111 and a driving circuit layer (or thin film transistor layer, TFT layer) 112, a pixel defining layer (PDL) 113 and an encapsulation layer (TFE) 117 sequentially stacked on the substrate 111. The pixel defining layer 113 is formed with an array-arranged opening. An organic light-emitting functional layer (EL) is provided in the opening of the pixel defining layer 113. The organic light-emitting functional layer (EL) includes, for example, a red organic light-emitting functional layer 114, a green organic light-emitting functional layer 115 and a blue organic light-emitting functional layer 116. The red organic light-emitting functional layer 114 corresponds to a red sub-pixel, the green organic light-emitting functional layer 115 corresponds to a green sub-pixel, and the blue organic light-emitting functional layer 116 corresponds to a blue sub-pixel, thereby forming red sub-pixels, green sub-pixels and blue sub-pixels arranged in an array on the substrate 111. Then, as shown in FIG. Figure 1 As shown, the pixel defining layer 113 is provided with a red pixel opening 1134 corresponding to the red sub-pixel, a green pixel opening 1135 corresponding to the green sub-pixel, and a blue pixel opening 1136 corresponding to the blue sub-pixel. For example, an anode (not shown) is provided below each organic light-emitting functional layer, and a cathode (not shown) is provided above the pixel defining layer 113 to cover the entire surface.

[0034] In a specific example, the OLED display device 100 may further include a touch layer (not shown) located on the light-emitting side of the OLED display panel 110, and the OLED display panel 110 may further include a film structure such as a buffer layer located between the substrate 111 and the driving circuit layer 112. For example, the organic light-emitting functional layer includes a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a light-emitting layer (EML), a hole blocking layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL). For example, the encapsulation layer 117 may be a composite encapsulation layer including a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked.

[0035] for Figure 1 The OLED display device 100 shown:

[0036] On the one hand, if Figure 2As shown, when ambient light (natural light) passes through a polarizer 130, for example, whose absorption axis is vertical, the vertically polarized light in the ambient light is absorbed, while the horizontally polarized light in the ambient light is transmitted. The horizontally polarized light in the ambient light transmitted by the polarizer 130 is converted to right-handed circularly polarized light after passing through the quarter-wave plate 120. This right-handed circularly polarized light is reflected by the cathode, anode, and other metal layers of the OLED display panel 110 of the OLED display device 100, and then rotated 180° to become left-handed circularly polarized light. This left-handed circularly polarized light is converted to vertically polarized light after passing through the ¼λ wave plate again. This vertically polarized light is absorbed by the polarizer 130 and cannot pass through the polarizer 130. Thus, the circular polarizer formed by the quarter-wave plate 120 and the polarizer 130 eliminates the reflection of ambient light from the OLED display panel 110 of the OLED display device 100, thereby ensuring the contrast of the OLED display panel 110 of the OLED display device 100.

[0037] On the other hand, Figure 3 As shown, the outgoing light (natural light) from the OLED display panel 110 of the OLED display device 100 remains natural light after passing through the quarter-wave plate 120. When passing through the polarizer 130, for example, whose absorption axis is in a vertical direction, the vertically polarized light in the outgoing light is absorbed and the horizontally polarized light in the outgoing light is transmitted. This will cause the light extraction efficiency of the OLED display panel 110 of the OLED display device 100 to be greatly reduced, theoretically only around 50%. If the set brightness is to be maintained, the driving power of the light emission needs to be increased, resulting in increased power consumption of the OLED display device 100.

[0038] In order to solve the problem of low light extraction efficiency in the first embodiment, the second embodiment proposes an OLED display device provided with a circular polarizer and a cholesteric liquid crystal film (CLC), in order to improve light extraction efficiency and reduce power consumption of the OLED display panel. Figure 1 The OLED display device 100 provided with a circular polarizer according to the first embodiment is different in that Figure 4As shown, the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film according to the second embodiment includes a cholesteric liquid crystal film 210 between the OLED display panel 110 and the quarter-wave plate 120. Specifically, the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film according to the second embodiment includes the OLED display panel 110, the cholesteric liquid crystal film 210, the quarter-wave plate 120, and the polarizer 130. The quarter-wave plate 120 and the polarizer 130 constitute a circular polarizer. The cholesteric liquid crystal film 210 is configured to transmit one of left-handed circularly polarized light and right-handed circularly polarized light in a set wavelength band of light belonging to the blue light band and reflect the other. The angle between the slow axis of the quarter-wave plate 120 and the absorption axis of the polarizer 130 is set so that the polarizer 130 transmits the circularly polarized light passing through the quarter-wave plate 120. For example, the cholesteric liquid crystal film 210 is bonded and fixed to the light-emitting side of the OLED display panel 110 through an adhesive layer 291 such as a pressure-sensitive adhesive (PSA), the quarter-wave plate 120 is bonded and fixed to the side of the cholesteric liquid crystal film 210 away from the OLED display panel 110 through an adhesive layer 292 such as a transparent optical adhesive, and the polarizer 130 is bonded and fixed to the side of the quarter-wave plate 120 away from the OLED display panel 110 through an adhesive layer 293 such as a transparent optical adhesive.

[0039] Cholesteric liquid crystal film 210 is a polymer composite film material comprising liquid crystal monomers and chiral additives. Adding the chiral additive to the liquid crystal molecules can twist their orientation, forming a cholesteric phase with a specific helical pitch. In the present invention, the chiral additive is doped to a concentration of less than 10% by weight.

[0040] The cholesteric phase is an important phase of liquid crystal molecules. In this phase, liquid crystal molecules are arranged in layers and have a continuous helical structure. Liquid crystal molecules in the cholesteric phase can be left-handed or right-handed.

[0041] For example, liquid crystal molecules in a cholesteric phase are left-handed. When natural light strikes the left-handed liquid crystal molecules, they Bragg reflect part of the incident light, while the remaining part is transmitted through the liquid crystal molecules. The reflected light is left-handed circularly polarized light within a certain wavelength or wavelength band (wavelength range), which can be referred to as the reflection wavelength or reflection band. The transmitted light is right-handed circularly polarized light within the reflection wavelength or reflection band, as well as incident light outside the reflection wavelength or reflection band.

[0042] For example, liquid crystal molecules in the cholesteric phase are right-handed. When natural light strikes the right-handed liquid crystal molecules, they Bragg reflect part of the incident light, while the remaining part is transmitted through the liquid crystal molecules. The reflected light is right-handed circularly polarized light within a certain wavelength or wavelength band, which can be referred to as the reflection wavelength or wavelength band. The transmitted light is left-handed circularly polarized light within the reflection wavelength or wavelength band, as well as incident light outside the reflection wavelength or wavelength band.

[0043] Therefore, the liquid crystal molecules in the cholesteric phase can achieve selective reflection, that is, the cholesteric liquid crystal film 210 can achieve selective reflection.

[0044] In a possible implementation, the cholesteric liquid crystal film 210 transmits one of left-handed circularly polarized light and right-handed circularly polarized light in a set wavelength band of blue light and reflects the other by setting the pitch of liquid crystal molecules.

[0045] Due to the unique helical structure of cholesteric liquid crystals, their degree of helical orientation is greater than 80%, resulting in Bragg reflection properties. This means that when the wavelength of incident light satisfies λ = np, the incident light will be reflected, where λ is the reflection wavelength or reflection band; P is the helical pitch of the cholesteric liquid crystal, i.e., the distance over which the orientation direction of the liquid crystal molecules undergoes a 360° change; and n is the average refractive index of the liquid crystal. Generally speaking, the average refractive index n of liquid crystals is relatively fixed, with the average refractive index of the liquid crystal monomers being 1.4 ≤ n ≤ 1.6, and the refractive index difference being 0.05 ≤ Δn < 0.3. Therefore, this implementation controls the reflection wavelength or reflection band of the cholesteric liquid crystal film 210 by setting or adjusting the helical pitch P.

[0046] Compared with red and green sub-pixels, the conversion efficiency of the organic light-emitting material of the blue sub-pixel is low, and the light extraction efficiency of the blue sub-pixel is low. Therefore, in this embodiment, the reflection band of the cholesteric liquid crystal film 210 is set to a set band belonging to the blue light band, so that the cholesteric liquid crystal film 210 reflects the blue light emitted by the blue sub-pixel, or reflects the blue light in the light emitted by the OLED display panel 110 of the OLED display device 200, so as to improve the light extraction efficiency of the blue sub-pixel, or improve the light extraction efficiency of the blue light in the light emitted by the OLED display panel 110 of the OLED display device 200.

[0047] In a possible implementation, the set wavelength band is 430 nm-490 nm.

[0048] For example, the central wavelength of the blue light emitted by the OLED display panel 110 is 460nm. Theoretically, it is sufficient to design the set band to include the range of 460nm, the central wavelength of the blue light emitted by the OLED display panel 110. However, the present implementation adopts a wider set band design of 430nm-490nm, which can better achieve the improvement of the blue light extraction efficiency.

[0049] The approximate optical path of the outgoing light from the OLED display panel 110 of the OLED display device 200 is as follows: the cholesteric liquid crystal film 210 transmits one of the left-handed circularly polarized light and the right-handed circularly polarized light in the blue light within a set wavelength band in the outgoing light, and reflects the other. The angle between the slow axis of the quarter-wave plate 120 and the absorption axis of the polarizer 130 is set so that the polarizer 130 transmits the circularly polarized light passing through the quarter-wave plate 120. However, the cholesteric liquid crystal film 210 has no effect on the red light and the green light in the outgoing light that are not within the set wavelength band. Almost all of the red light and the green light in the outgoing light are transmitted through the cholesteric liquid crystal film 210 and enter the quarter-wave plate 120 in the form of natural light.

[0050] Taking the cholesteric phase liquid crystal molecules of the cholesteric liquid crystal film 210 as left-handed liquid crystal molecules as an example, the specific light path of the emitted light is as follows: Figure 5 As shown:

[0051] For the blue light within the set wavelength band emitted by the blue light organic light emitting functional layer 116 corresponding to the blue light sub-pixel, when passing through the cholesteric liquid crystal film 210, the right-handed circularly polarized light accounting for 50% of the total light amount in the blue light is transmitted and the left-handed circularly polarized light accounting for 50% of the total light amount is reflected by the cholesteric liquid crystal film 210. On the one hand, the right-handed circularly polarized light accounting for 50% of the total light amount is converted into horizontally polarized light after passing through the quarter-wave plate 120, and is then transmitted by the polarizer 130 with the absorption axis in the vertical direction. On the other hand, the left-handed circularly polarized light accounting for 50% of the total light amount is rotated 180° after being reflected by the metal layers such as the cathode and anode of the OLED display panel 110 and becomes horizontally polarized light. Right-handed circularly polarized light, the right-handed circularly polarized light reflected by the OLED display panel 110 becomes horizontally polarized light after passing through the quarter-wave plate 120, and is then transmitted by the polarizer 130 with the absorption axis in the vertical direction. In this way, when the reflectivity of the OLED display panel 110 is, for example, 35% to 40%, the blue light output efficiency of the blue light organic light-emitting functional layer 116 corresponding to the blue light sub-pixel within the set wavelength band can theoretically reach 50% + 50% × (35% to 40%). Compared with Example 1, the improvement in the blue light output efficiency can reach about 30%, thereby reducing the power consumption by about 15%.

[0052] The cholesteric liquid crystal film 210 has no effect on the green light emitted by the green organic light emitting functional layer 115 corresponding to the green sub-pixel and the red light emitted by the red organic light emitting functional layer 114 corresponding to the red sub-pixel. Almost all of the red and green light in the emitted light is transmitted through the cholesteric liquid crystal film 210 and enters the quarter-wave plate 120 in the form of natural light. The cholesteric liquid crystal film 210 does not affect the light extraction efficiency of the red and green light in the emitted light. Figure 6 As shown, Figure 6 In the figure, the horizontal axis represents the reflection wavelength band of the cholesteric liquid crystal film 210, and the vertical axis represents the reflectivity of the cholesteric liquid crystal film 210. It can be seen that the reflectivity of the cholesteric liquid crystal film 210 for blue light (the central wavelength of the red light emitted by the OLED display panel 110 is 460 nm) with a set wavelength band of 430 nm to 490 nm is approximately 50%, and the transmittance for red light (the central wavelength of the red light emitted by the OLED display panel 110 is 620 nm) and green light (the central wavelength of the green light emitted by the OLED display panel 110 is 5400 nm) is greater than 90%. Figure 7 As shown, Figure 7 In the figure, the horizontal axis represents the reflection wavelength of the cholesteric liquid crystal film 210, the vertical axis represents the optical power of the output light, and the dotted line represents the optical power curve of the OLED display device 100 provided with a circular polarizer according to Example 1. It can be seen that the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film according to Example 2 can effectively improve the light extraction efficiency of blue light.

[0053] It can be seen that the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film as proposed in the second embodiment can effectively improve the light extraction efficiency of blue light. However, on the other hand, the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film as proposed in the second embodiment will increase the reflectivity of ambient light and cause a blue reflection color cast.

[0054] For example, since the cholesteric liquid crystal film 210 does not affect the light outside the set wavelength band (including red light and green light) in the external ambient light (natural light), the optical path of the light outside the set wavelength band (including red light and green light) reflected by the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film is as follows: Figure 2 As shown, the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film can substantially completely eliminate light outside the set wavelength band (including red light and green light) in the external ambient light (natural light). However, the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film cannot substantially completely eliminate the blue light in the set wavelength band of the external ambient light, but will produce a certain amount of reflection, for example Figure 8The OLED display device 200 shown in the figure is provided with a circular polarizer and a cholesteric liquid crystal film to reflect the light of the set wavelength band of the blue light in the ambient light: when the blue light of the set wavelength band in the external ambient light passes through the polarizer 130 with an absorption axis in a vertical direction, the vertically polarized light in the ambient light is absorbed and the horizontally polarized light in the ambient light is transmitted. The horizontally polarized light in the blue light transmitted by the polarizer 130 is converted into right-handed circularly polarized light after passing through the quarter-wave plate 120. The right-handed circularly polarized light is absorbed by the cholesteric liquid crystal film. After being transmitted through the liquid crystal film 210, it is reflected by the OLED display panel 110 and rotated 180° to become left-handed circularly polarized light. This left-handed circularly polarized light is reflected by the cholesteric liquid crystal film 210. After being reflected by the OLED display panel 110, this left-handed circularly polarized light is rotated 180° to become right-handed circularly polarized light. This right-handed circularly polarized light is transmitted by the cholesteric liquid crystal film 210 and then passes through the ¼λ wave plate to become horizontally polarized light. This horizontally polarized light is then transmitted by the polarizer 130. It can be seen that the OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film in the second embodiment can improve the blue light extraction efficiency of the OLED display panel 110, but it will cause reflection of blue light in the set blue light band within the external ambient light, thereby increasing the reflectivity of the ambient light and causing a blue reflection color shift.

[0055] In order to solve the problem of increased ambient light reflectivity and blue reflection color shift in the second embodiment, the third embodiment proposes an OLED display device provided with a circular polarizer, a cholesteric liquid crystal film and a light shielding layer, in order to ensure the effect of improving the light output efficiency of the display panel while reducing the reflection of ambient light by the display panel and improving the color shift caused by the reflection of blue light in the ambient light by the display panel. Figure 4 The OLED display device 200 provided with a circular polarizer and a cholesteric liquid crystal film according to the second embodiment is different in that Figure 9As shown, the OLED display device 300 provided with a circular polarizer, a cholesteric liquid crystal film, and a light-shielding layer, as proposed in the third embodiment, includes a light-shielding layer 310 between the OLED display panel 110 and the cholesteric liquid crystal film 210. Specifically, the OLED display device 300 provided with a circular polarizer, a cholesteric liquid crystal film, and a light-shielding layer, as proposed in the third embodiment, includes the OLED display panel 110, the light-shielding layer 310, the cholesteric liquid crystal film 210, a quarter-wave plate 120, and a polarizer 130. The quarter-wave plate 120 and the polarizer 130 constitute a circular polarizer. The cholesteric liquid crystal film 210 is configured to transmit one of left-handed circularly polarized light and right-handed circularly polarized light within a set wavelength band of light belonging to the blue light band, and to reflect the other. The angle between the slow axis of the quarter-wave plate 120 and the absorption axis of the polarizer 130 is set so that the polarizer 130 transmits the circularly polarized light passing through the quarter-wave plate 120. The light shielding layer 310 is provided with a first opening 314 corresponding to the red sub-pixel, a second opening 315 corresponding to the green sub-pixel, and a third opening 316 corresponding to the blue sub-pixel. Figure 9 As shown, the first opening 314 corresponds to the red organic light emitting functional layer 114 corresponding to the red sub-pixel, the second opening 315 corresponds to the green organic light emitting functional layer 115 corresponding to the green sub-pixel, and the third opening 316 corresponds to the blue organic light emitting functional layer 116 corresponding to the blue sub-pixel.

[0056] Thus, while utilizing the cholesteric liquid crystal film 210 to effectively improve the light extraction efficiency of blue light, the light shielding layer 310, such as the black matrix (BM) layer, can absorb the blue light of the set wavelength band belonging to the blue light band in the external ambient light at the position corresponding to the pixel definition layer 113 in the orthogonal projection, so that the OLED display device 300 provided with the circular polarizer, the cholesteric liquid crystal film and the light shielding layer will not cause the reflection of the blue light of the set wavelength band belonging to the blue light band in the external ambient light at the position corresponding to the pixel definition layer 113 in the orthogonal projection, thereby, the blue light of the set wavelength band belonging to the blue light band in the external ambient light is not reflected at the position corresponding to the pixel definition layer 113 in the orthogonal projection, and ... Under the premise that the opening 315 and the third opening 316 avoid affecting the light output of the OLED display panel 110, while utilizing the cholesteric liquid crystal film 210 to effectively improve the light output efficiency of blue light, the reflection of ambient light by the OLED display panel 110 caused by the provision of the cholesteric liquid crystal film 210 is reduced, and the color shift caused by the reflection of blue light in the ambient light is improved. Among them, it has been verified through experiments that the reflectivity of the OLED display panel 110 to ambient light due to the provision of the cholesteric liquid crystal film 210 can be reduced to below 6%, and the color shift value caused by the reflection of blue light in the ambient light can be controlled within ±3.

[0057] It is understandable that in the OLED display device 300 provided with a circular polarizer, a cholesteric liquid crystal film and a light shielding layer, at the positions corresponding to the red sub-pixels, the green sub-pixels and the blue sub-pixels, the light path of the light of the set wavelength band belonging to the blue light band in the ambient light is reflected, for example Figure 8 As shown, however, at a position of the pixel defining layer 113 corresponding to a considerable proportion of the orthographic projection, when the blue light of the external ambient light belonging to the set blue light band passes through, for example, the polarizer 130 with an absorption axis in a vertical direction, the vertically polarized light in the ambient light is absorbed and the horizontally polarized light in the ambient light is transmitted. The horizontally polarized light in the blue light transmitted by the polarizer 130 is converted into right-handed circularly polarized light after passing through the quarter-wave plate 120. The right-handed circularly polarized light is transmitted by the cholesteric liquid crystal film 210 and then absorbed by the shading pattern of the shading layer 310, for example, the black matrix, and cannot form a reflection.

[0058] In one possible implementation, Figure 9 As shown, the orthographic projection of the first opening 314 on the substrate 111 covers the orthographic projection of the corresponding red pixel opening 1134 on the substrate 111, the orthographic projection of the second opening 315 on the substrate 111 covers the orthographic projection of the corresponding green pixel opening 1135 on the substrate 111, and the orthographic projection of the third opening 316 on the substrate 111 covers the orthographic projection of the corresponding blue pixel opening 1136 on the substrate 111. In this way, it is further ensured that the light shielding layer 310 does not affect the light output of the OLED display panel 110.

[0059] Furthermore, in a possible implementation, as Figure 9 As shown, the orthographic projection area of ​​the first opening 314 on the substrate 111 is larger than the orthographic projection area of ​​the corresponding red pixel opening 1134 on the substrate 111, the orthographic projection area of ​​the second opening 315 on the substrate 111 is larger than the orthographic projection area of ​​the corresponding green pixel opening 1135 on the substrate 111, and the orthographic projection area of ​​the third opening 316 on the substrate 111 is larger than the orthographic projection area of ​​the corresponding blue pixel opening 1136 on the substrate 111. As a result, there is a height difference between the light shielding layer 310 and the pixel defining layer 113 ( Figure 9 Therefore, this implementation can further ensure that the light shielding layer 310 does not affect the light output of the OLED display panel 110, ensuring that the display content can be viewed at an oblique viewing angle in addition to the normal viewing angle.

[0060] Furthermore, in a possible implementation, as Figure 9As shown, the ratio of the area of ​​the orthographic projection of the third opening 316 on the substrate 111 to the area of ​​the orthographic projection of the corresponding blue light pixel opening 1136 on the substrate 111 is respectively greater than the ratio of the area of ​​the orthographic projection of the first opening 314 on the substrate 111 to the area of ​​the orthographic projection of the corresponding red light pixel opening 1134 on the substrate 111 and the ratio of the area of ​​the orthographic projection of the second opening 315 on the substrate 111 to the area of ​​the orthographic projection of the corresponding green light pixel opening 1135 on the substrate 111. That is, the ratio of the area of ​​the orthographic projection of the third opening 316 on the substrate 111 to the area of ​​the orthographic projection of the corresponding blue light pixel opening 1136 on the substrate 111 is greater than the ratio of the area of ​​the orthographic projection of the first opening 314 on the substrate 111 to the area of ​​the orthographic projection of the corresponding red light pixel opening 1134 on the substrate 111, and the ratio of the area of ​​the orthographic projection of the third opening 316 on the substrate 111 to the area of ​​the orthographic projection of the corresponding blue light pixel opening 1136 on the substrate 111 is greater than the ratio of the area of ​​the orthographic projection of the second opening 315 on the substrate 111 to the area of ​​the orthographic projection of the corresponding green light pixel opening 1135 on the substrate 111.

[0061] The inventors discovered that at oblique viewing angles, blue light decays faster than red and green light. Therefore, by adopting this implementation's design with a larger opening ratio in the light-shielding layer corresponding to the blue sub-pixel, the blue light decay rate can be slowed down at oblique viewing angles, thereby balancing the decay rates of red, green, and blue light and improving color shift at oblique viewing angles.

[0062] It should be noted that Figure 9As shown, the area of ​​the orthographic projection of the red sub-pixel (i.e., the red light organic light emitting functional layer 114) on the substrate 111, the area of ​​the orthographic projection of the green sub-pixel (i.e., the green light organic light emitting functional layer 115) on the substrate 111, and the area of ​​the orthographic projection of the blue sub-pixel (i.e., the blue light organic light emitting functional layer 116) on the substrate 111 are the same, and the areas of the orthographic projections of the red light pixel opening 1134 corresponding to the red light sub-pixel, the green light pixel opening 1135 corresponding to the green light sub-pixel, and the blue light pixel opening 1136 corresponding to the blue light sub-pixel opened in the pixel defining layer 113 on the substrate 111 are also the same. Therefore, this implementation method can also be described as the area of ​​the orthographic projection of the third opening 316 on the substrate 111 being larger than the area of ​​the orthographic projection of the first opening 314 on the substrate 111 and the area of ​​the orthographic projection of the second opening 315 on the substrate 111, respectively. However, in some designs, there are designs in which the size of the blue light sub-pixel is larger, that is, the area of ​​the blue light sub-pixel (that is, the blue light organic light-emitting functional layer 116) on the substrate 111 is larger than the area of ​​the red light sub-pixel (that is, the red light organic light-emitting functional layer 114) on the substrate 111 and the area of ​​the green light sub-pixel (that is, the green light organic light-emitting functional layer 115) on the substrate 111, that is, the area of ​​the blue light pixel opening 1136 on the substrate 111 is larger than the area of ​​the red light pixel opening 1134 on the substrate 111 and the area of ​​the green light pixel opening 1135 on the substrate 111. In this way, according to the above-mentioned ratio limitation, a design with a larger light-shielding layer opening ratio corresponding to the blue light sub-pixel can be determined.

[0063] In a possible implementation, in embodiments 1 to 3, the display device further includes a half-wave plate disposed between the quarter-wave plate and the polarizer. Figure 9 As shown, the OLED display device 300 provided with a circular polarizer, a cholesteric liquid crystal film, and a light shielding layer according to the third embodiment further includes a half-wave plate 320 disposed between the quarter-wave plate 120 and the polarizer 130. The half-wave plate 320 serves as a color adjustment layer for color correction, further reducing the reflection of ambient light from the OLED display panel 110.

[0064] In a possible implementation, in embodiments 1 to 3, the quarter wave plate 120 is a liquid crystal quarter wave plate, and / or the half wave plate is a liquid crystal half wave plate, for example Figure 9 The half-wave plate 320 shown is a liquid crystal half-wave plate. For example, in the third embodiment, the quarter-wave plate 120 and the half-wave plate 320 are each a liquid crystal wave plate or an LC polarizing film. For example, the LC polarizing film is composed of an alignment layer and a liquid crystal polymer layer, and the liquid crystal polymer layer is formed by the polymerization and curing of reactive liquid crystals with mutually perpendicular orientations.

[0065] In one possible implementation, in embodiments one to three, the polarizer 130 is a polyvinyl alcohol polarizer, that is, the material of the polarizing layer 130 is polyvinyl alcohol (PVA). Exemplarily, the polarizing layer 130 can be an iodine-based polarizing layer, which is obtained by dyeing with iodine dye and has polarizing properties based on the optical dichroism of the crystal. Specifically, the PVA film can be immersed in an iodine ion solution so that the iodine ions diffuse into the PVA film. After slight heating and stretching, the PVA film becomes longer and also becomes narrower and thinner. The PVA molecules are originally randomly distributed at any angle. After being stretched by force, they gradually deflect in the direction of the force. The iodine molecules with dichroism attached to the PVA also follow the direction, thereby forming the polarizing layer 130. The polarizing layer 130 has an absorption axis and has the function of converting natural light into linearly polarized light. For example, it absorbs vertically polarized light and passes horizontally polarized light, thereby converting natural light into linearly polarized light.

[0066] In a specific example, when the half wave plate 320 is provided, the quarter wave plate 120 and the half wave plate 320 are respectively provided on a plane parallel to the substrate 111 ( Figure 9 The polarizer 130 has a fast axis and a slow axis in the horizontal plane (in the wave plate) (the direction of the light vector with slow propagation speed in the wave plate is the slow axis, and the direction of the light vector with fast propagation speed is the fast axis), the angle between the absorption axis of the polarizer 130 and the slow axis of the half wave plate 320 is set to an acute angle α≈15°, and the angle between the absorption axis of the polarizer 130 and the slow axis of the quarter wave plate 120 is set to 2α+45° (α≈15°, then this angle 2α+45° is about 75°); when the half wave plate 320 is not set, the angle between the absorption axis of the polarizer 130 and the slow axis of the quarter wave plate 120 can be set to be approximately equal to ±45°.

[0067] For example, when the liquid crystal molecules in the cholesteric phase of the cholesteric liquid crystal film 210 are right-handed liquid crystal molecules, the absorption axis of the polarizing layer 130 needs to be rotated 90°, which can still achieve the purposes of the second and third embodiments.

[0068] In a possible implementation, in embodiments 1 to 3, the OLED display device further includes a cover plate disposed on a side of the polarizer 130 away from the quarter-wave plate 120. For example, Figure 9 As shown, the OLED display device 300 provided with a circular polarizer, a cholesteric liquid crystal film and a light shielding layer proposed in the third embodiment further includes a substrate layer 330 and a cover plate 340 provided on a side of the polarizer 130 away from the quarter-wave plate 120 .

[0069] In a specific example, the material of the cover plate 340 can be one of transparent polyimide (CPI), polyethylene terephthalate (PET), ultra-thin glass (UTG), and the like. Furthermore, the cover plate 340 is not limited to a single layer and can be two or more layers. When the cover plate 340 is two or more layers, the materials of each layer can be the same or different.

[0070] In a specific example, Figure 9 As shown, in the OLED display device 300 provided with a circular polarizer, a cholesteric liquid crystal film, and a light shielding layer proposed in the third embodiment, the cholesteric liquid crystal film 210 is bonded and fixed to the side of the light shielding layer 310 away from the OLED display panel 110 by an adhesive layer 391 such as a pressure sensitive adhesive (PSA), the quarter wave plate 120 is bonded and fixed to the side of the cholesteric liquid crystal film 210 away from the OLED display panel 110 by an adhesive layer 392 such as a transparent optical adhesive, and the half wave plate 320 is bonded and fixed to the side of the cholesteric liquid crystal film 210 away from the OLED display panel 110 by an adhesive layer 393 such as a transparent optical adhesive. The polarizer 130 is bonded and fixed to the side of the quarter-wave plate 120 away from the OLED display panel 110. The polarizer 130 is bonded and fixed to the side of the half-wave plate 320 away from the OLED display panel 110 via an adhesive layer 394, such as a transparent optical adhesive. The substrate layer 330 is bonded and fixed to the side of the polarizer 130 away from the OLED display panel 110 via an adhesive layer 395, such as a transparent optical adhesive. The cover plate 340 is bonded and fixed to the side of the substrate layer 330 away from the OLED display panel 110 via an adhesive layer 396, such as a transparent optical adhesive. In addition, the adhesive layers 391-396 can also be other types of adhesive layers, such as ultraviolet curing adhesive (UV adhesive) and heat-curing water-based adhesive.

[0071] The OLED display device provided in the above embodiment can be any product or component with display function, such as electronic paper, mobile phone, tablet computer, television, monitor, notebook computer, digital photo frame, navigator, etc., and this embodiment does not limit this.

[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in this field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A display device, characterized in that: The invention comprises a display panel and a light-shielding layer, a cholesteric liquid crystal film, a quarter-wave plate, and a polarizer sequentially arranged on a light-emitting side of the display panel. The display panel comprises a substrate and red sub-pixels, green sub-pixels, and blue sub-pixels arranged in an array on the substrate. The cholesteric liquid crystal film is used to transmit one of left-handed circularly polarized light and right-handed circularly polarized light in light of a set wavelength band belonging to the blue light band and reflect the other. The angle between the slow axis of the quarter-wave plate and the absorption axis of the polarizer is set so that the polarizer transmits the circularly polarized light passing through the quarter-wave plate. The light-shielding layer is provided with a first opening corresponding to the red sub-pixel, a second opening corresponding to the green sub-pixel, and a third opening corresponding to the blue sub-pixel. The display panel includes a pixel defining layer arranged on the substrate, the pixel defining layer is provided with a red light pixel opening corresponding to the red light sub-pixel, a green light pixel opening corresponding to the green light sub-pixel, and a blue light pixel opening corresponding to the blue light sub-pixel, the orthographic projection of the first opening on the substrate covers the orthographic projection of the corresponding red light pixel opening on the substrate, the orthographic projection of the second opening on the substrate covers the orthographic projection of the corresponding green light pixel opening on the substrate, and the orthographic projection of the third opening on the substrate covers the orthographic projection of the corresponding blue light pixel opening on the substrate.

2. The display device according to claim 1, wherein The area of ​​the orthographic projection of the first opening on the substrate is larger than the area of ​​the orthographic projection of the corresponding red light pixel opening on the substrate, the area of ​​the orthographic projection of the second opening on the substrate is larger than the area of ​​the orthographic projection of the corresponding green light pixel opening on the substrate, and the area of ​​the orthographic projection of the third opening on the substrate is larger than the area of ​​the orthographic projection of the corresponding blue light pixel opening on the substrate.

3. The display device according to claim 1 or 2, characterized in that The ratio of the area of ​​the orthographic projection of the third opening on the substrate to the area of ​​the orthographic projection of the corresponding blue light pixel opening on the substrate is respectively greater than the ratio of the area of ​​the orthographic projection of the first opening on the substrate to the area of ​​the orthographic projection of the corresponding red light pixel opening on the substrate and the ratio of the area of ​​the orthographic projection of the second opening on the substrate to the area of ​​the orthographic projection of the corresponding green light pixel opening on the substrate.

4. The display device according to claim 1, wherein The set wavelength band is 430nm-490nm.

5. The display device according to claim 1, wherein The cholesteric liquid crystal film transmits one of left-handed circularly polarized light and right-handed circularly polarized light in a set wavelength band of blue light and reflects the other by setting the pitch of liquid crystal molecules.

6. The display device according to claim 1, wherein The display device further includes a half-wave plate disposed between the quarter-wave plate and the polarizer.

7. The display device according to claim 6, wherein: The quarter wave plate is a liquid crystal quarter wave plate, and / or the half wave plate is a liquid crystal half wave plate.

8. The display device according to claim 1, wherein The polarizer is a polyvinyl alcohol polarizer.

9. The display device according to claim 1, wherein The display device further includes a cover plate arranged on a side of the polarizer away from the quarter-wave plate.

10. The display device according to claim 1, wherein The display panel is an organic light emitting diode display panel.

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