OLED (Organic Light Emitting Diode) display strabismus character point regulation and control structure and preparation method thereof

Abstract

The invention discloses an OLED display strabismus character point regulation and control structure and a preparation method, the structure comprises a micro lens structure located on an OLED display, the micro lens structure comprises a plurality of micro lens units, and the micro lens units are the same in structure and are in one-to-one correspondence with sub-pixels in the OLED display; each micro lens unit comprises a transparent optical layer, a micro lens and a filling layer which are sequentially arranged from bottom to top; by regulating and controlling the thickness of the transparent optical layer, the light condensation effect of the micro-lens unit is adjusted, and the situation of a squint color point of the OLED display is further improved. By regulating the thickness of the transparent optical layer, the red, green and blue sub-pixel micro lenses have different light gathering effects, so that the strabismus angle point condition is improved.

Description

Technical Field

[0001] This invention relates to the field of OLED microdisplay technology, and in particular to an OLED display slant point control structure and its fabrication method. Background Technology

[0002] like Figure 2 As shown, in an OLED structure, the OLED light-emitting layer consists of a stacked encapsulation layer, a color filter layer, a transparent optical layer, microlenses, a filler layer, and glass. Each of these layers has a different refractive index, thus forming a multi-layered optical interface. Since OLEDs emit red, green, and blue light with different wavelengths, and different wavelengths of light have different refractive indices in the same medium (the shorter the wavelength, the higher the refractive index), the red, green, and blue light are deflected at different optical interfaces. This results in a difference in the red, green, and blue ratio of the final emitted light at an oblique viewing angle compared to at a normal viewing angle; this phenomenon is also known as oblique view color deflection.

[0003] Especially in OLED displays with microlenses, the working principle of microlenses is to converge light from an oblique viewing angle to a normal viewing angle through refractive index and optical interface angle. In this process, RGB light of different wavelengths has different converging effects due to different refractive indices, so the intensity ratio of light from the oblique viewing angle is completely different from that from the normal viewing angle, resulting in more severe color shift.

[0004] The table below shows the differences in the color point and the proportion of red, green and blue brightness at the normal and oblique viewing angles of an OLED screen with a microlens structure. CIE X and CIE Y refer to the coordinates of the color point, i.e., the coordinate parameters on the chromaticity diagram. It can be seen that at the oblique viewing angle, CIEX increases and CIEY decreases, the proportion of red increases significantly and the proportion of green decreases significantly.

[0005]

[0006] For the first case, where different wavelengths of light have different refractive indices, resulting in color shift due to different deflection angles of different colors from the light-emitting layer to the final light emission in OLED devices, the common approach in existing technologies is to change the refractive indices between the various film layers to perform optical interface matching and reduce the impact of different wavelengths of light having different refractive indices in the same medium. However, this method is extremely difficult to adjust and cannot completely solve the problem.

[0007] Regarding the second scenario, namely the color shift caused by the different deflection angles of light of different wavelengths in the MLA (microlens array) in OLED displays with microlenses, no good solution has been found in the industry. Summary of the Invention

[0008] Technical objective: To address the deficiencies in existing technologies, this invention discloses an OLED display slant corner control structure and its fabrication method. By adjusting the thickness of the transparent optical layer, the red, green, and blue sub-pixel microlenses can achieve different light-gathering effects, thereby improving the slant corner situation.

[0009] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution.

[0010] An OLED display slant view pixel adjustment structure includes: a microlens structure located on the OLED display, the microlens structure including a plurality of microlens units, each microlens unit having the same structure and corresponding one-to-one with a sub-pixel in the OLED display; the microlens unit includes a transparent optical layer, a microlens, and a filling layer arranged sequentially from bottom to top; by adjusting the thickness of the transparent optical layer, the light-gathering effect of the microlens unit can be adjusted, thereby improving the slant view pixel situation of the OLED display.

[0011] A method for fabricating a slant-viewing point control structure for an OLED display includes the following steps: Step 1: Configure the OLED display substrate; Step 2: Fabricate the transparent optical layer material of the first sub-pixel on the OLED display substrate; Step 3: Fabricate the transparent optical layer material of the second sub-pixel on the OLED display substrate; Step 4: Fabricate the transparent optical layer material of the third sub-pixel on the OLED display substrate; complete the fabrication of the transparent optical layer for all microlens units in the microlens structure; Step 5: Fabricate microlenses on the transparent optical layer materials of the three sub-pixels respectively; Step 6: Prepare a filling layer on the microlens and the transparent optical layer to complete the fabrication of the control structure.

[0012] Beneficial effects: This invention sets different transparent optical layer thicknesses for RGB sub-pixels, so that the microlenses of the RGB sub-pixels and the light-emitting layer have different distances. By adjusting this distance, different light-gathering effects of the microlenses are achieved, thereby realizing the adjustment of RGB brightness ratio for oblique viewing angles and improving color points. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the OLED display slant view character point control structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of an OLED display in the prior art; Figure 3 Schematic diagram of light intensity at different viewing angles under different thicknesses of transparent optical layers; Figure 4A simplified schematic diagram of the microlens unit; Figure 5 This is a process flow diagram of a fabrication method for an OLED display slant-viewing character point control structure according to an embodiment of the present invention. Figure 1 ; Figure 6 This is a process flow diagram of a fabrication method for an OLED display slant-viewing character point control structure according to an embodiment of the present invention. Figure 2 . Detailed Implementation

[0014] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application. Example

[0015] As attached Figure 1 As shown in the figure, an OLED display slant view pixel adjustment structure of this embodiment includes: a microlens structure located on the OLED display, the microlens structure including a plurality of microlens units, each microlens unit having the same structure and corresponding one-to-one with a sub-pixel in the OLED display; the microlens unit includes a transparent optical layer, a microlens, and a filling layer arranged sequentially from bottom to top; by adjusting the thickness of the transparent optical layer, the light-gathering effect of the microlens unit can be adjusted, thereby improving the slant view pixel situation of the OLED display.

[0016] In OLED displays, the thickness of the transparent optical layer in the microlens unit corresponding to the blue subpixel is less than that in the microlens unit corresponding to the green subpixel, and the thickness of the transparent optical layer in the microlens unit corresponding to the green subpixel is less than that in the microlens unit corresponding to the red subpixel. The thickness of the transparent optical layer in the microlens unit corresponding to the blue subpixel ranges from 0 to 2 μm; the thickness of the transparent optical layer in the microlens unit corresponding to the green subpixel ranges from 0.5 to 4 μm; and the thickness of the transparent optical layer in the microlens unit corresponding to the red subpixel ranges from 1 to 6 μm.

[0017] The formula for controlling the thickness of the transparent optical layer is: Where A is the distance from the light-emitting layer to the microlens, D is the width of the microlens, H is the height of the microlens, and n is the refractive index of the microlens, which is related to the wavelength of the light source transmitted through the microlens.

[0018] The transparent optical layer is a transparent material, which can be an organic adhesive or a transparent medium such as SiO or SIO. The organic adhesive can be an optically transparent adhesive.

[0019] The filler layer is a low refractive index layer with a refractive index range of 1.35 to 1.45, and is made of organic materials such as acrylate.

[0020] It should be noted that the microlens shape, refractive index ratio, and transparent optical layer thickness affect the light-gathering effect of the microlens. The thickness of the transparent optical layer actually affects the distance between the microlens and the light source, i.e., the focal point of the microlens. Different transparent optical layers produce different deflection effects, resulting in different light intensity ratios at the normal and oblique viewing angles. Typically, the shape and refractive index of the microlens are difficult to change within the same display screen. Therefore, this invention designs an oblique viewing angle brightness control structure for OLED displays. In this structure, different color sub-pixels have transparent optical layers of different heights. By designing the thickness of the transparent optical layers for the red, green, and blue sub-pixels, the oblique viewing angle brightness of the three sub-pixels is corrected to maintain consistency, thereby mitigating the difference in oblique viewing angle brightness caused by the different refractive indices of red, green, and blue light. Figure 3 The light intensity at different viewing angles is given for different thicknesses of the transparent optical layer.

[0021] The derivation of the formula for controlling the thickness of the transparent optical layer is given below.

[0022] The microlens unit is simplified to the following model, where the distance from the light-emitting layer to the microlens is defined as A. Figure 1 and Figure 4 As can be seen, the light-emitting layer is located in the OLED layer of the OLED display. The distance A from the light-emitting layer to the microlens includes the thickness of the transparent optical layer, the thickness of the color filter layer, the thickness of the encapsulation layer, and the thickness of other possible structural layers in the OLED device. The width of the microlens is defined as D, the height of the microlens is defined as H, the wavelength of the light source is defined as λ, and the refractive index of the microlens is defined as n.

[0023] The relationship between wavelength and refractive index is as follows: Where C is the fundamental refractive index of the microlens material and B is the dispersion constant of the material.

[0024] The focusing power of a microlens is defined by the half-angle θ of the outgoing light cone. When the light source is at the focal point of the lens, the outgoing light is parallel, and the focusing effect is strongest. When the point source is out of focus, the outgoing light converges, and the defocusing amount is... According to geometric relationships, the half-angle θ of the outgoing light cone satisfies... .

[0025] The focal length formula is f = R / (n-1), where R is the radius of curvature of the microlens. Therefore, it can be derived that: .

[0026] Therefore, the half-angle of the emitted light cone ; As can be seen from this formula, when the parameters H and D related to the microlens morphology are fixed, θ first decreases and then increases with A. It has the strongest light-focusing effect.

[0027] Different colored subpixels have transparent optical layers of varying heights. Theoretical calculations and experimental tests show that the transparent optical layer is thinnest for blue subpixels and thickest for red subpixels. The thickness of the transparent optical layer for blue subpixels is between 0 and 2 μm, for red subpixels between 1 and 6 μm, and for green subpixels between 0.5 and 4 μm.

[0028] In the control structure of this invention, different transparent optical layer thicknesses are set for RGB sub-pixels, so that the microlenses of the RGB sub-pixels and the light-emitting layer have different distances. By adjusting this distance, different light-gathering effects of the microlenses are achieved, thereby realizing the adjustment of RGB brightness ratio for oblique viewing angles and improving color points.

[0029] This invention also provides a method for preparing an OLED display slant corner control structure, comprising the following steps: Step 1: Configure the OLED display substrate; Step 2: Fabricate the transparent optical layer material of the first sub-pixel on the OLED display substrate; Step 3: Fabricate the transparent optical layer material of the second sub-pixel on the OLED display substrate; Step 4: Prepare the transparent optical layer material of the third sub-pixel on the OLED display substrate; complete the preparation of the transparent optical layer of all microlens units in the microlens structure; the first to third sub-pixels are red, green and blue sub-pixels respectively, and there is no restriction on the order.

[0030] Step 5: Fabricate microlenses on the transparent optical layer materials of the three sub-pixels respectively; Step 6: Prepare a filling layer on the microlens and the transparent optical layer to complete the fabrication of the control structure.

[0031] The transparent optical layer material preparation process in steps two to four is the same, including: spin-coating transparent optical layer material on all sub-pixels, covering the transparent optical layer material corresponding to a certain sub-pixel with the transparent optical layer material corresponding to other sub-pixels, exposing and developing the entire device, and removing the transparent optical layer material corresponding to other sub-pixels.

[0032] In some embodiments of the present invention, such as Figure 5 and Figure 6 As shown, the transparent optical layer material is optically transparent adhesive. A method for fabricating an OLED display's oblique viewing angle dot control structure includes the following steps: Step S1: Configure the OLED display substrate; Step S2: Spin-coat optically transparent adhesive onto the OLED display substrate; Step S3: After covering the transparent optical layer materials corresponding to the red and green sub-pixels with the transparent optical layer material corresponding to the blue sub-pixel, expose the entire device. Step S4: Develop the device to remove the transparent optical layer material corresponding to the red and green sub-pixels, and complete the preparation of the transparent optical layer material corresponding to the blue sub-pixel; Step S5: Repeat steps S2 to S4 to complete the preparation of the transparent optical layer material corresponding to the green sub-pixel; Step S6: Repeat steps S2 to S4 to complete the preparation of the transparent optical layer material corresponding to the red sub-pixel.

[0033] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A slant-viewing character point adjustment structure for an OLED display, characterized in that, include: The microlens structure located on top of the OLED display includes several microlens units, each with the same structure and corresponding one-to-one with a sub-pixel in the OLED display. Each microlens unit includes a transparent optical layer, a microlens, and a filling layer arranged sequentially from bottom to top. By adjusting the thickness of the transparent optical layer, the light-gathering effect of the microlens unit can be adjusted, thereby improving the situation of the OLED display's slanted pixel.

2. The OLED display slant angle adjustment structure according to claim 1, characterized in that, The thickness of the transparent optical layer in the microlens unit corresponding to the blue sub-pixel is less than that in the microlens unit corresponding to the green sub-pixel, and the thickness of the transparent optical layer in the microlens unit corresponding to the green sub-pixel is less than that in the microlens unit corresponding to the red sub-pixel.

3. The OLED display slant angle adjustment structure according to claim 2, characterized in that, The thickness of the transparent optical layer in the microlens unit corresponding to the blue subpixel ranges from 0 to 2 μm; the thickness of the transparent optical layer in the microlens unit corresponding to the green subpixel ranges from 0.5 to 4 μm; and the thickness of the transparent optical layer in the microlens unit corresponding to the red subpixel ranges from 1 to 6 μm.

4. The OLED display slant angle adjustment structure according to claim 1, characterized in that, The formula for controlling the thickness of the transparent optical layer is: Where A is the distance from the light-emitting layer to the microlens, D is the width of the microlens, H is the height of the microlens, and n is the refractive index of the microlens, which is related to the wavelength of the light source transmitted through the microlens.

5. The OLED display slant angle adjustment structure according to claim 1, characterized in that, The transparent optical layer is made of transparent material, which is either organic adhesive or a transparent medium.

6. The OLED display slant angle adjustment structure according to claim 1, characterized in that, The filling layer is a low refractive index layer with a refractive index range of 1.35 to 1.45, and the material is organic.

7. A method for fabricating a slanted character point control structure for an OLED display, characterized in that: Includes the following steps: Step 1: Configure the OLED display substrate; Step 2: Fabricate the transparent optical layer material of the first sub-pixel on the OLED display substrate; Step 3: Fabricate the transparent optical layer material of the second sub-pixel on the OLED display substrate; Step 4: Fabricate the transparent optical layer material of the third sub-pixel on the OLED display substrate; complete the fabrication of the transparent optical layer for all microlens units in the microlens structure; the first to third sub-pixels are red, green, and blue sub-pixels, respectively; Step 5: Fabricate microlenses on the transparent optical layer materials of the three sub-pixels respectively; Step 6: Prepare a filling layer on the microlens and the transparent optical layer to complete the fabrication of the control structure.

8. The method for preparing an OLED display slant-viewing character point control structure according to claim 7, characterized in that: The transparent optical layer material preparation process in steps two through four is the same, including: spin-coating transparent optical layer material on all sub-pixels, covering the transparent optical layer material corresponding to a certain sub-pixel with the transparent optical layer material corresponding to other sub-pixels, exposing and developing the entire device, and removing the transparent optical layer material corresponding to other sub-pixels.

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