Peep-proof OLED display panel

Abstract

The utility model relates to the technical field of OLED (Organic Light Emitting Diode) display panels, in particular to a peep-proof OLED display panel, which comprises a plurality of pixel units, and a first type cholesteric liquid crystal film with a first color is arranged above each pixel unit; a 1 / 4 wave plate and a polaroid are sequentially formed above the first type cholesteric liquid crystal film; polarized light in oblique emergent light generated by adjacent pixel units sequentially penetrates through the first type cholesteric liquid crystal thin film, the 1 / 4 wave plate and the polaroid to be absorbed. The cholesteric liquid crystal display panel has the advantages that a traditional light mixing box or a black matrix block with the corresponding thickness is replaced with the combination of the cholesteric liquid crystal film, the slide and the polaroid, the low panel thickness is achieved, meanwhile, the cholesteric liquid crystal film conducts transmission and internal reflection on circularly polarized light emitted in the inclined direction, and the display quality is improved. And the inclined light is absorbed through the combination of the slide and the polaroid, so that the brightness of the light in the squint direction is effectively reduced, and the problem of privacy leakage at a large angle is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of OLED display panels, and particularly relates to an anti-peeping OLED display panel. Background Technique

[0002] OLED (Organic Light-Emitting Diode), also known as organic electroluminescent display and organic light-emitting semiconductor (Organic Electroluminescence Display, OLED). OLED belongs to a current-type organic light-emitting device, and is a phenomenon of luminescence caused by the injection and recombination of carriers, and the luminescence intensity is proportional to the injected current. Under the action of an electric field, holes generated by the anode and electrons generated by the cathode will move, and are respectively injected into the hole transport layer and the electron transport layer, and migrate to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated, which excite the light-emitting molecules to finally generate visible light. The display device based on the OLED principle has the advantages of high brightness, wide viewing angle, high contrast, etc. However, in some application scenarios, an overly large viewing angle may cause privacy leakage problems, and an anti-peeping design needs to be introduced.

[0003] In the prior art, there already exist display panels that implement anti-peeping design at the device level.

[0004] For example, the patent document WO2020244289A1 discloses an anti-peeping display panel and an anti-peeping display device, including a plurality of pixel units, each pixel unit including a plurality of sub-pixels; a color filter layer, including a plurality of color filter units corresponding to the plurality of sub-pixels one by one, each color filter unit configured to filter the light emitted by the corresponding sub-pixel; and a black matrix layer, including a plurality of black matrices, each black matrix located at the adjacency of adjacent color filter units and the black matrix configured to block at least part of the light emitted by the sub-pixel adjacent to the black matrix, the angle between the emission direction of the at least part of the light and the normal of the light-emitting surface of the sub-pixel being greater than or equal to 40°, and the anti-peeping function is achieved through the black matrix layer.

[0005] For another example, the patent document WO2023193132A1 discloses a display panel with switchable wide and narrow viewing angles, a driving method, and a display device. The display panel has a patterned identification pattern area and a non-identification pattern area, and includes a dimming cell and a display cell stacked on top of each other; the dimming cell includes a first substrate, a second substrate, and a first liquid crystal layer. The first substrate is provided with a common viewing angle electrode, and the second substrate is provided with a first viewing angle electrode and a second viewing angle electrode that cooperate with the common viewing angle electrode. The first viewing angle electrode corresponds to the identification pattern area, and the second viewing angle electrode corresponds to the non-identification pattern area; in the wide viewing angle mode, the first viewing angle electrode and the second viewing angle electrode are applied with electrical signals of the same amplitude, and the light transmittance of the identification pattern area and the non-identification pattern area is the same at the same side viewing angle; in the narrow viewing angle mode, the first viewing angle electrode and the second viewing angle electrode are applied with electrical signals of different amplitudes, and the light transmittance of the identification pattern area and the non-identification pattern area is different at the same side viewing angle.

[0006] However, in the actual implementation process, the inventors found that such technical solutions would lead to a significant increase in the thickness of the display panel. For example, adding an additional dimming cell in the panel would cause the thickness to increase, and when the black matrix layer is used to control the angle of the outgoing light, a certain thickness is required, etc. These technical means would all lead to an increase in the panel thickness. Summary of the Utility Model

[0007] In view of the above problems existing in the prior art, a privacy OLED display panel is provided herein.

[0008] The specific technical solutions are as follows:

[0009] A privacy OLED display panel includes a plurality of pixel units, and a first type of cholesteric liquid crystal film of a first color is respectively disposed above each of the pixel units;

[0010] A quarter-wave plate and a polarizer are sequentially formed above the first type of cholesteric liquid crystal film;

[0011] The polarized light in the obliquely outgoing light generated by adjacent pixel units is sequentially absorbed through the first type of cholesteric liquid crystal film, the quarter-wave plate, and the polarizer.

[0012] On the other hand, the first-direction circularly polarized light contained in the obliquely outgoing light passes through the first type of cholesteric liquid crystal film and exits;

[0013] The second-direction circularly polarized light contained in the obliquely outgoing light is reflected twice on the surface of the first type of cholesteric liquid crystal film and the pixel unit to be converted into the first-direction circularly polarized light and then exits through the first type of cholesteric liquid crystal film;

[0014] The direction of the second-direction circularly polarized light is opposite to that of the first-direction circularly polarized light.

[0015] On the other hand, the first-direction circularly polarized light is left-handed circularly polarized light, the second-direction circularly polarized light is right-handed circularly polarized light, and the third-direction linearly polarized light is horizontally polarized light.

[0016] On the other hand, the first-direction circularly polarized light is right-handed circularly polarized light, the second-direction circularly polarized light is left-handed circularly polarized light, and the third-direction linearly polarized light is vertically polarized light.

[0017] On the other hand, a spacing area is provided between the pixel units;

[0018] A black coating area is provided between predetermined positions corresponding to the spacing area above the first-type cholesteric liquid crystal film.

[0019] On the other hand, a vertical louver layer is provided above the polarizer.

[0020] On the other hand, the first color is blue.

[0021] On the other hand, the first color is the color corresponding to the pixel unit.

[0022] On the other hand, a spacing area is provided between the pixel units;

[0023] The first-type cholesteric liquid crystal film is provided with a colored area and a transition area arranged at intervals in the horizontal direction, and the transition area is located above the spacing area;

[0024] The first color corresponding to the pixel unit is respectively formed in the colored area.

[0025] On the other hand, it further includes:

[0026] A substrate, on which the pixel units and the spacing area arranged at intervals are formed above;

[0027] A cathode layer, which is formed above the pixel units and the spacing area;

[0028] An encapsulation layer, which is formed above the cathode layer, and the first-type cholesteric liquid crystal film is located above the encapsulation layer.

[0029] The above technical solutions have the following advantages or beneficial effects:

[0030] In view of the problem that the anti-peeping design in the prior art can cause a significant increase in the panel thickness, in this solution, by replacing the traditional mixing light box or black matrix block with a corresponding thickness with a combination of a cholesteric liquid crystal film, a glass slide, and a polarizer, a lower panel thickness is achieved. At the same time, the cholesteric liquid crystal film transmits and internally reflects the circularly polarized light emitted obliquely, and the combination of the glass slide and the polarizer absorbs the inclined light, effectively reducing the light brightness in the oblique viewing direction and avoiding the problem of privacy leakage at large angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] With reference to the accompanying drawings, the embodiments of the present invention will be described more fully. However, the accompanying drawings are only for illustration and explanation, and do not constitute a limitation on the scope of the present invention.

[0032] Figure 1 It is a schematic diagram of the whole of the embodiment of the present invention;

[0033] Figure 2 It is a schematic diagram of another embodiment of the present invention;

[0034] Figure 3 It is a schematic diagram of the louver curtain layer in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not limited to the present invention.

[0038] The present invention includes:

[0039] An anti-peeping OLED display panel, as Figure 1 shown, includes a plurality of pixel units 1, and a first type of cholesteric liquid crystal film 2 of a first color is respectively disposed above each pixel unit 1;

[0040] Above the first type of cholesteric liquid crystal film 2, a quarter-wave plate 3 and a polarizer 4 are sequentially formed;

[0041] The obliquely emitted light generated by the adjacent pixel unit 1 passes through the first type cholesteric liquid crystal film 2 and is emitted as circularly polarized light in the first direction;

[0042] The circularly polarized light in the first direction is converted into linearly polarized light in the third direction by the quarter wave plate 3 and is absorbed by the polarizer 4 .

[0043] The second direction circularly polarized light contained in the obliquely emitted light is twice reflected on the surface of the first type cholesteric liquid crystal film 2 and the pixel unit 1 to be converted into the first direction circularly polarized light and then emitted through the first type cholesteric liquid crystal film 2;

[0044] The direction of the second circularly polarized light is opposite to the direction of the first circularly polarized light.

[0045] Specifically, to control the viewing angle of the display panel, this embodiment suppresses polarized light emitted obliquely from pixel unit 1, thereby reducing screen brightness in the oblique viewing direction and achieving a privacy protection effect. Furthermore, since only a cholesteric liquid crystal film, a quarter-wave plate 3, and a polarizer 4 are added, their thickness is significantly reduced compared to a traditional electrically controlled light mixing box with a black matrix block of a specific thickness.

[0046] Specifically, a plurality of pixel units 1 are provided in the OLED display panel, and a spacing region 6 is provided between the pixel units 1 to separate pixel units 1 of different colors. An encapsulation layer 8 is covered above the pixel units 1 and the spacing region 6 to flatten the device surface.

[0047] On this basis, a first type of cholesteric liquid crystal film 2 is disposed above the encapsulation layer 8. This cholesteric liquid crystal film is composed of cholesteric liquid crystals, which have a unique helical structure. By adjusting the degree of helical orientation, it can reflect specific wavelengths of light. Generally speaking, when the helical orientation is greater than 80%, the incident light will be reflected when the wavelength λ = np, where n is the average refractive index of the liquid crystal and p is the helical pitch of the cholesteric liquid crystal.

[0048] Taking the blue pixel unit 1 as an example, the left and right sides of the blue pixel unit 1 can be configured with non-blue first type cholesteric liquid crystal films 2, and the first direction can be configured as left-handed circularly polarized light. Then, when the blue pixel unit 1 emits light, the blue pixel unit 1 will project oblique output light toward the first type cholesteric liquid crystal film 2 in the adjacent direction.

[0049] The left-handed circularly polarized light component therein will exit through the first-type cholesteric liquid crystal film 2, while the right-handed circularly polarized light component will be reflected back to the surface of the pixel unit 1 by the first-type cholesteric liquid crystal film 2. Since the surface of an OLED device usually has an electrode layer configured thereon and has a certain reflectivity, the right-handed circularly polarized light will be secondarily reflected into left-handed circularly polarized light and reflected upward after reaching the electrode layer, and then pass through the first-type cholesteric liquid crystal film 2 and exit.

[0050] At this time, the polarized light part exiting through the first-type cholesteric liquid crystal film 2 only contains the left-handed circularly polarized light component. After passing through the quarter-wave plate 3, it will be deflected into vertically polarized light, and then absorbed by the polarizer 4 above, weakening the intensity of the polarized light in this direction and increasing the light intensity attenuation rate at an oblique viewing angle, thereby achieving the anti-peeping effect.

[0051] In the implementation process, the above combination can generally be implemented by selecting two embodiments:

[0052] Embodiment 1:

[0053] The circularly polarized light in the first direction is left-handed circularly polarized light, and the circularly polarized light in the second direction is right-handed circularly polarized light. At this time, the first-type cholesteric liquid crystal film 2 is a right-handed cholesteric liquid crystal film, which will reflect right-handed circularly polarized light and transmit left-handed circularly polarized light;

[0054] The left-handed circularly polarized light is converted into horizontally polarized light after passing through the quarter-wave plate 3 and absorbed by the polarizer 4 above.

[0055] Embodiment 2:

[0056] The circularly polarized light in the first direction is right-handed circularly polarized light, and the circularly polarized light in the second direction is left-handed circularly polarized light. At this time, the first-type cholesteric liquid crystal film 2 is a left-handed cholesteric liquid crystal film, which will reflect left-handed circularly polarized light and transmit right-handed circularly polarized light;

[0057] The right-handed circularly polarized light is converted into vertically polarized light after passing through the quarter-wave plate 3 and absorbed by the polarizer 4 above.

[0058] In the implementation process, the above technical solution is mainly used to manufacture a display panel composed of OLED devices. The display panel usually also includes other parts.

[0059] For example, in one embodiment, it further includes:

[0060] A substrate 5, on which pixel units 1 arranged at intervals and an interval area 6 are formed; a cathode layer 7, which is formed above the pixel units 1 and the interval area 6;

[0061] An encapsulation layer 8, which is formed above the cathode layer 7, and the first-type cholesteric liquid crystal film 2 is located above the encapsulation layer 8.

[0062] Specifically, a plurality of pixel units 1 are defined above the substrate 5. The pixel units 1 arranged at intervals are arranged according to a specific cell structure, and different colors are configured at predetermined positions to form a light-emitting array, such as an RBGB matrix, an RYYB matrix, etc. Between each pixel unit 1, in order to distinguish the pixel units 1 and avoid pixel crosstalk, an interval region 6 is usually configured.

[0063] The interval region 6 is a protruding portion formed by depositing or etching on the substrate 5. Usually, the cross-section is trapezoidal or other shapes, and it is higher than the light-emitting material deposited in the pixel unit 1. Above this, a cathode layer 7 is formed to cover the pixel unit 1 and the interval region 6. Depending on the device type, it may also include an electron transport layer, a hole injection layer, a hole transport layer, and so on. Since the interval region 6 is significantly higher than the pixel unit 1, in order to planarize the device, a packaging layer 8 is also provided to wrap the underlying structure. An anode metal layer 9 is formed on the back of the substrate 5 through a back processing process.

[0064] On this basis, the corresponding cholesteric liquid crystal film, wave plate, polarizer 4, etc. can be prepared according to the above structure.

[0065] Usually, the first color corresponds to the color of the pixel unit 1, that is, a red cholesteric liquid crystal film is set above the red pixel unit, a green cholesteric liquid crystal film is set above the green pixel unit, and a blue cholesteric liquid crystal film is set above the blue pixel unit. This setting can also enhance the light output in the vertical light-emitting direction of the corresponding pixel unit 1.

[0066] Specifically, taking the example of a left-handed cholesteric liquid crystal film set above the green pixel unit, among the light emitted from the green pixel unit, the right-handed circularly polarized light can pass through the left-handed cholesteric liquid crystal film, while the left-handed circularly polarized light cannot pass through the left-handed cholesteric liquid crystal film and is reflected by the metal electrode layer to become right-handed circularly polarized light and then passes through the left-handed cholesteric liquid crystal film again.

[0067] After passing through the left-handed cholesteric liquid crystal film, since all are right-handed circularly polarized light, by controlling the direction of the 1 / 4 wave plate at this time, the right-handed circularly polarized light will not be converted into vertically polarized light and absorbed by the polarizer, thereby improving the light output rate.

[0068] A set of transition regions should be configured between the cholesteric liquid crystal films of different colors. This transition region has no specific color. The two sides of the transition region are colored regions configured with the corresponding colors. The colored regions should be located above the pixel unit 1 and have the first color corresponding to the pixel unit 1.

[0069] Correspondingly, the transition region should be located above the interval region 6 between the pixel units 1.

[0070] Furthermore, after studying the imaging process of the display panel, the inventor found that compared with red light and green light, blue light has a faster attenuation rate. When controlling the polarization light intensity of blue light while keeping the light intensities of other colors unchanged, a relatively serious color shift phenomenon will occur at the oblique viewing angle, affecting normal viewing.

[0071] Based on this characteristic, the following embodiments can also be provided:

[0072] Embodiment 3:

[0073] The first color is blue. Above the blue pixel unit 1, a blue left-handed cholesteric liquid crystal film 21 is arranged, and blue right-handed cholesteric liquid crystal films 22 are arranged on both sides. When the blue pixel unit 1 generates blue light and obliquely irradiates into the blue right-handed cholesteric liquid crystal film 22.

[0074] The left-handed circularly polarized light in the blue oblique light passes through the blue right-handed cholesteric liquid crystal film 22 and is converted into vertical polarized light by the quarter-wave plate 3 and absorbed by the polarizer 4;

[0075] The right-handed circularly polarized light component is reflected by the blue right-handed cholesteric liquid crystal film 22, is reflected and rotated 180° at the cathode layer 7 to become left-handed circularly polarized light, passes through the blue right-handed cholesteric liquid crystal film, is converted into vertical polarized light by the quarter-wave plate 3 and absorbed by the polarizer 4, achieving the purpose of anti-peeping at the oblique viewing angle and not affecting the emission of red and green light.

[0076] As an additional technical means, on the basis of the above technical solution, other structures can be added to further reduce the viewing angle. For example:

[0077] In one embodiment, a spacer region 6 is provided between the pixel units 1;

[0078] A black coating region 10 is provided between the predetermined positions corresponding to the spacer region 6 above the first type of cholesteric liquid crystal film 2.

[0079] The black coating region 10 is used to absorb the light obliquely emitted by the pixel unit 1, thereby reducing the light emitted in the oblique direction. The black coating region 10 can be spaced from the quarter-wave plate 3 to form a light-emitting window in the vertical direction without affecting the brightness in the frontal viewing direction.

[0080] In one embodiment, a vertical louver layer 11 is provided above the polarizer 4.

[0081] Specifically, to achieve the control of light emission in the inclined direction, in this embodiment, a vertical louver layer 11 is provided above the polarizer 4. The louver layer 11 can be manufactured by processes such as deposition - lithography. Its structure is an ultra - fine micro - louver with a grid - shaped opening and a certain height, which is used to control the light emission in the inclined direction.

[0082] The above are only the preferred embodiments of the present utility model, and do not limit the implementation manners and protection scope of the present utility model accordingly. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the description and illustrations of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An anti-peeping OLED display panel, comprising a plurality of pixel units, characterized in that, Above each of the pixel units, a first-type cholesteric liquid crystal film of a first color is respectively provided. Above the first-type cholesteric liquid crystal film, a quarter-wave plate and a polarizer are sequentially formed. The polarized light in the obliquely emitted light generated by adjacent pixel units is sequentially transmitted through the first-type cholesteric liquid crystal film, the quarter-wave plate and the polarizer and absorbed. A spacer region is provided between the pixel units. Above the first-type cholesteric liquid crystal film, a black coating region is provided between predetermined positions corresponding to the spacer region.

2. The anti-peeping OLED display panel according to claim 1, wherein, The first-direction circularly polarized light contained in the obliquely emitted light exits through the first-type cholesteric liquid crystal film. The second-direction circularly polarized light contained in the obliquely emitted light is doubly reflected on the surface of the first-type cholesteric liquid crystal film and the pixel unit to be converted into the first-direction circularly polarized light and then exits through the first-type cholesteric liquid crystal film. The direction of the second-direction circularly polarized light is opposite to the direction of the first-direction circularly polarized light.

3. The anti-peeping OLED display panel according to claim 2, characterized in that, The first-direction circularly polarized light is left-handed circularly polarized light, the second-direction circularly polarized light is right-handed circularly polarized light, and the third-direction linearly polarized light is horizontally polarized light.

4. The anti-peeping OLED display panel according to claim 2, wherein The first-direction circularly polarized light is right-handed circularly polarized light, the second-direction circularly polarized light is left-handed circularly polarized light, and the third-direction linearly polarized light is vertically polarized light.

5. The anti-peeping OLED display panel according to claim 1, characterized in that Above the polarizer, a vertical louver layer is provided.

6. The anti-peeping OLED display panel according to claim 1, wherein The first color is blue.

7. The anti-peeping OLED display panel according to claim 1, characterized in that, The first color corresponds to the color of the pixel unit.

8. The anti-peeping OLED display panel according to claim 7, wherein, A spacer region is provided between the pixel units. The first-type cholesteric liquid crystal film is horizontally and spacedly provided with a coloring region and a transition region, and the transition region is located above the spacer region. The first color corresponding to the pixel unit is respectively formed in the coloring region.

9. The anti-peep OLED display panel according to claim 1, wherein Further included are: A substrate, above which the pixel units and the spacer regions arranged at intervals are formed. A cathode layer, which is formed above the pixel units and the spacer regions. A packaging layer, which is formed above the cathode layer, and the first-type cholesteric liquid crystal film is located above the packaging layer.

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