TWI885441B - Switchable 3d display - Google Patents

Abstract

A switchable 3D display which includes a display module, an array lens layer and a liquid crystal lens overlapping the display surface of the display module is provided. An image light emitting from the surface of the display module, and both the array lens layer and the liquid crystal lens are located on the light path of the image light. The first spacing is between the surface of the liquid crystal and the light-incident surface of the array lens layer, while the second spacing is between the surface of the liquid crystal and the surface of the display module. When the switchable 3D display shows a 2D image, the liquid crystal performs as a lens mode. Since the focal length of this lens mode is between the first spacing and the second spacing, the image light diverges after passing through the liquid crystal lens. When the switchable 3D display shows a 3D image, the liquid crystal performs as a transparent mode, so that the image light is not deflected after passing through the liquid crystal lens.

Description

Switchable stereo display device

The present invention relates to a stereoscopic display device, in particular to a stereoscopic display device that can be switched to a 2D display state.

Today's stereoscopic display technology can be divided into: wearable stereoscopic display technology that requires the observer to view through special devices (such as glasses), and naked-eye stereoscopic display technology that can be viewed directly with the naked eye. Lens-type (lenticular lens) is one type of naked-eye stereoscopic display technology. Its stereoscopic imaging method is to set a film with parallel cylindrical lenses in front of the display screen. Because the cylindrical lenses on this film can change the direction of light travel, the left eye image light passes through the film and is refracted to reach the user's left eye, and the right eye image light passes through the film and is refracted to reach the user's right eye. When the user's left and right eyes see their corresponding image screens respectively, parallax will be generated, thereby presenting a stereoscopic display effect.

However, when the stereo display device needs to display two-dimensional images, the light deflection effect of the cylindrical lens will cause the same pixel to display different brightness or color grayscale at different angles, resulting in inconsistent two-dimensional images viewed from different angles. For example, when displaying two-dimensional text, at a fixed viewing angle, the display pixels under the same line cannot be displayed continuously, so the edges of the text will be jagged or even broken, making the text blurry and affecting the user's viewing experience.

An embodiment of the present invention provides a switchable stereoscopic display device that can clearly display two-dimensional images.

At least one embodiment of the present invention provides a switchable stereoscopic display device including a display module, a lens array layer, and a liquid crystal lens. The display module has a display surface, and the display module emits an image light from the display surface. The lens array layer is disposed above the display surface and includes a plurality of parallel cylindrical lenses. The liquid crystal lens is disposed above the display surface and overlaps with the lens array layer, wherein the liquid crystal lens and the lens array layer are both located on the transmission path of the image light. There is a first distance between a surface of the liquid crystal lens and a light incident surface of the lens array layer, and there is a second distance between this surface of the liquid crystal lens and the display surface of the display module. When the switchable stereoscopic display device performs two-dimensional image display, the liquid crystal lens is in a lens mode and has a focal length. The focal length range falls between the first distance and the second distance, so that the liquid crystal lens in the lens mode is used to disperse the image light. When the switchable stereoscopic display device performs three-dimensional image display, the liquid crystal lens is in a transparent mode and does not deflect the image light.

In at least one embodiment of the present invention, the liquid crystal lens of the switchable stereoscopic display device further includes a liquid crystal layer and two electrode layers. The two electrode layers are respectively located on opposite sides of the liquid crystal layer, wherein each of the electrode layers includes a plurality of parallel electrode groups, and each of these electrode groups extends along the first direction.

In at least one embodiment of the present invention, the long axis of each cylindrical lens extends along a second direction, and there is an angle between the first direction and the second direction, and the angle is not 0°.

In at least one embodiment of the present invention, the angle ranges from 0° to 50°.

In at least one embodiment of the present invention, each cylindrical lens has a width, and each electrode group has a perimeter, wherein the perimeter of the electrode group is smaller than the width of the cylindrical lens.

In at least one embodiment of the present invention, the switchable stereoscopic display device further includes a light-transmitting layer, which is located on the lens array layer and directly contacts the columnar lens, wherein the refractive index of the light-transmitting layer is less than the refractive index of the lens array layer.

In at least one embodiment of the present invention, the lens array layer is located between the liquid crystal lens and the display module.

In at least one embodiment of the present invention, the switchable stereoscopic display device further includes a polarizer located between the lens array layer and the display module.

In at least one embodiment of the present invention, the switchable stereoscopic display device further includes a polarizer located between the lens array layer and the liquid crystal lens.

In at least one embodiment of the present invention, the liquid crystal lens is located between the lens array layer and the display module.

In the above-mentioned embodiment, a liquid crystal lens is provided in the switchable stereoscopic display device, and the mode of the liquid crystal lens is switched for two-dimensional display and three-dimensional display. When in three-dimensional display, the liquid crystal lens is in a transparent mode, and this transparent mode does not change the direction of the image light after passing through the lens array layer. However, in the case of two-dimensional display, the liquid crystal material in the liquid crystal lens is driven to deflect to different degrees, thereby forming a lens mode with a lens effect. This lens mode can cause the image light to produce divergent deflection to partially offset the focusing deflection caused by the lens array layer, thereby improving the unevenness of the plane image. This helps improve the quality of the 2D display without affecting the 3D display.

10: Switchable stereo display device

100: Display module

100s: Display surface

102: Color filter substrate

120: Lens array layer

120i: light-entering surface

122: cylindrical lens

122c: Surface

140: Liquid crystal lens

140s: Surface

142:Liquid crystal layer

142M: Liquid crystal molecules

144,146:Electrode layer

145a: First strip electrode

145b: Second strip electrode

147: Dielectric layer

148: Translucent substrate

160: Translucent layer

180: Polarizer

A1: Center axis

D1: First direction

D2: Second direction

d1: first spacing

d2: Second spacing

G1, G2: electrode group

M1: Image light

P1: Distance

W1: Width

θ1: angle of intersection

The present invention can be understood from the following detailed description and the accompanying drawings. It should be noted that various features are not drawn to the scale that is standard in industry practice. In fact, the size of various features may be arbitrarily increased or decreased for the sake of clarity of discussion.

FIG1 shows a cross-sectional view of a switchable stereoscopic display device according to an embodiment of the present invention.

Figure 2 shows a partial three-dimensional diagram of a liquid crystal lens in an embodiment of the present invention.

Figure 3 shows a partial three-dimensional diagram of the lens array layer in one embodiment of the present invention.

FIG4 is a partial top view of a switchable stereoscopic display device according to an embodiment of the present invention.

FIG5A is a side view schematic diagram of a switchable stereoscopic display device according to another embodiment of the present invention.

FIG5B is a side view schematic diagram of a switchable stereoscopic display device according to another embodiment of the present invention.

The present invention will be described in detail with the following embodiments. It should be noted that the following description of the embodiments of the present invention is only used for illustration and is not intended to disclose all embodiments in detail or to limit the specific embodiments of the present invention. For example, the description of "a first feature formed on a second feature" includes a variety of implementations, including the first feature directly contacting the second feature and the additional feature formed between the first feature and the second feature so that the two do not directly contact. In addition, the same component symbols used in the drawings and the specification will represent the same or similar components as much as possible.

Spatially relative terms, such as "inferior", "lower than", "below", "above", "above", and related terms, are used here to simply describe the relationship between an element or feature as shown in the figure and another element or feature. These spatially relative terms cover different rotations when using or operating the device in addition to the rotation depicted in the figure. In addition, when the element can be rotated (rotated 90 degrees or other angles), the spatially relative descriptors used here can also be interpreted accordingly.

In the following text, in order to clearly present the technical features of the present invention, the dimensions (such as length, width, thickness and depth) of the components (such as layers, films, substrates and regions, etc.) in the drawings will be enlarged in a non-uniform manner. Therefore, the description and explanation of the following embodiments are not limited to the dimensions and shapes presented by the components in the drawings, but should cover the dimensions, shapes and deviations thereof caused by the actual process and/or tolerance. For example, the flat surface shown in the drawings may have rough and/or nonlinear features, and the sharp corners shown in the drawings may be rounded. Therefore, the components presented in the drawings of the present invention are mainly used for illustration, and are not intended to accurately depict the actual shape of the components, nor are they used to limit the scope of the patent application of the present invention.

Furthermore, the words "approximately", "approximately" or "substantially" used in the present case not only cover the numerical values and numerical ranges clearly stated, but also cover the permissible deviation ranges that can be understood by a person of ordinary skill in the art to which the invention belongs, wherein the deviation range can be determined by the errors produced during measurement, and such errors are caused, for example, by the limitations of the measurement system or process conditions. In addition, "approximately" can mean within one or more standard deviations of the above numerical values, such as ±30%, ±20%, ±10% or ±5%. The words "approximately", "approximately" or "substantially" used in this text may be used to select acceptable deviation ranges or standard deviations based on the optical properties, etching properties, mechanical properties or other properties. It does not mean that a single standard deviation is applied to all the above optical properties, etching properties, mechanical properties and other properties.

FIG1 is a switchable stereoscopic display device 10 of an embodiment of the present invention, and the switchable stereoscopic display device 10 includes a display module 100, a lens array layer 120, and a liquid crystal lens 140. The display module 100 has a display surface 100s, and the display module 100 emits image light M1 from the display surface 100s. In this embodiment, the display module 100 can be, for example, a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, or other similar displays.

As shown in FIG1 , the switchable stereoscopic display device 10 may include a color filter substrate 102, and the color filter substrate 102 is located on the display surface 100s of the display module 100. Although not shown in detail in the figure, the color filter substrate 102 may be a substrate including a color filter layer (e.g., an RGB filter layer), and the substrate may be, for example, a glass plate or a transparent plastic substrate.

The lens array layer 120 is disposed above the display surface 100s and is located on the color filter substrate 102. The lens array layer 120 includes a plurality of columnar lenses 122 arranged side by side, and the convex surfaces of these columnar lenses 122 protrude away from the display module 100. For example, in this embodiment, each columnar lens 122 of the lens array layer 120 can be a plano-convex lens. The planar surfaces of these plano-convex lenses face the display module 100, while the convex surfaces face away from the display module 100. The material of the lens array layer 120 can include, for example, ultraviolet curing resin (UV glue) or similar light-transmitting materials.

The liquid crystal lens 140 is disposed above the display surface 100s and overlaps with the lens array layer 120. As shown in FIG1 , both the liquid crystal lens 140 and the lens array layer 120 are located on the transmission path of the image light M1. In other words, when the image light M1 is emitted from the display module 100, it passes through the lens array layer 120 and the liquid crystal lens 140.

It is worth mentioning that although the lens array layer 120 of this embodiment is located between the liquid crystal lens 140 and the display module 100, so that the image light M1 first passes through the lens array layer 120 and reaches the liquid crystal lens 140, the present invention is not limited to this. In other embodiments, the liquid crystal lens 140 can also be located between the lens array layer 120 and the display module 100, so that the image light M1 first passes through the liquid crystal lens 140 and reaches the lens array layer 120.

Please refer to the partial three-dimensional diagram of the liquid crystal lens 140 shown in FIG2. The liquid crystal lens 140 further includes a liquid crystal layer 142 and an electrode layer 144 and an electrode layer 146, and the electrode layer 144 and the electrode layer 146 are respectively located on opposite sides of the liquid crystal layer 142. The electrode layer 144 and the electrode layer 146 respectively include a plurality of parallel electrode groups G1 and electrode groups G2, and each electrode group (electrode group G1 or electrode group G2) extends along the first direction D1.

For example, in this embodiment, the electrode layer 144 includes a plurality of parallel electrode groups G1 (FIG. 2 only shows one electrode group G1), and one electrode group G1 includes a plurality of first strip electrodes 145a and a second strip electrode 145b. On the other hand, the electrode layer 146 includes a plurality of parallel electrode groups G2 (FIG. 2 only shows one electrode group G2), and one electrode group G2 also includes a plurality of first strip electrodes 145a and a second strip electrode 145b. The material of the first strip electrode 145a and the second strip electrode 145b may include, for example, indium tin oxide (ITO) or a similar light-transmitting conductive material.

It is worth mentioning that in this embodiment, one electrode group G1 corresponds to one electrode group G2. When the liquid crystal lens 140 is powered on, an electrostatic field is formed between the electrode layer 144 and the electrode layer 146, so that the liquid crystal molecules 142M in the liquid crystal layer 142 generate induced charges, thereby driving the liquid crystal molecules 142M to rotate.

In addition, since the first strip electrode 145a and the second strip electrode 145b can generate electrostatic fields of different strengths, the electrostatic field between the pair of electrode groups G1 and G2 is unevenly distributed. Under the uneven electrostatic field, the rotation angles of each liquid crystal molecule 142M will be different. By designing the distribution of the first strip electrode 145a and the second strip electrode 145b, the rotation arrangement of the liquid crystal molecules 142M when the liquid crystal lens 140 is powered on can present a gradient distribution as shown in FIG. 2. When light passes through the liquid crystal molecules 142M with different rotation degrees, different degrees of deflection will be generated. Furthermore, since the rotation degree of the liquid crystal molecules 142M is arranged in a gradient, the refractive index change in the liquid crystal layer 142 is distributed in a gradient, so that the liquid crystal lens 140 can produce the effect of diverging or converging light like a lens.

However, the distribution of the first strip electrode 145a and the second strip electrode 145b of the electrode group G1 (and the electrode group G2) in the present invention is not limited to this embodiment. In various embodiments of the present invention, the electric field distribution between the electrode layer 144 and the electrode layer 146 can also be adjusted by other methods to make the rotation of the liquid crystal molecules 142M change in a gradient, thereby producing a lens effect.

Please refer to FIG1 , there is a first distance d1 between the surface 140s of the liquid crystal lens 140 and the light incident surface 120i of the lens array layer 120, wherein the surface 140s faces the lens array layer 120. On the other hand, there is a second distance d2 between the surface 140s of the liquid crystal lens 140 and the display surface 100s of the display module 100. When the switchable stereoscopic display device 10 performs a two-dimensional image display, the liquid crystal lens 140 can be placed in a lens mode (as shown in FIG2 ). The liquid crystal lens 140 in the lens mode is equivalent to a parallel cylindrical convex lens and has a focal length f1 (not shown), and the range of the focal length f1 falls between the first distance d1 and the second distance d2. This focal length range allows the liquid crystal lens 140 in the lens mode to diverge the image light M1. Specifically, as shown in FIG1 , after the image light M1 passes through the lens array layer 120 and the liquid crystal lens 140 in the lens mode, it will be deflected away from the central axis A1 of the cylindrical lens 122, causing the image light M1 to diverge.

However, when the switchable stereoscopic display device 10 performs three-dimensional image display, the liquid crystal lens 140 is in transparent mode and does not deflect the image light M1. Specifically, in transparent mode, the liquid crystal molecules 142M in the liquid crystal lens 140 are not driven by the electrostatic field to rotate. Therefore, the refractive index of the liquid crystal layer 142 is a fixed value and does not show a gradient change. In this way, the liquid crystal lens 140 will not produce the effect of diverging or converging light like a lens, that is, the liquid crystal lens 140 in transparent mode is equivalent to a glass plate. In particular, the above-mentioned "does not deflect the image light M1" means that after passing through the liquid crystal lens 140, the image light M1 will not be deflected away from the central axis A1 of the cylindrical lens 122, so the image light M1 cannot be diverged.

In addition, referring to FIG. 2 , the liquid crystal lens 140 further includes two dielectric layers 147 . The two dielectric layers 147 are respectively located on opposite sides of the liquid crystal layer 142 , and one dielectric layer 147 is located between the liquid crystal layer 142 and the electrode layer 144 , while the other dielectric layer 147 is located between the liquid crystal layer 142 and the electrode layer 146 . The dielectric layer 147 covers the strip electrodes on the electrode layer 144 (including the first strip electrodes 145a and the second strip electrodes 145b) and the strip electrodes on the electrode layer 146 (including the first strip electrodes 145a and the second strip electrodes 145b), so that the electrode layer 144 and the electrode layer 146 are separated from the liquid crystal layer 142. The dielectric layer 147 may include, for example, silicon dioxide ( _SiO2 ) or a similar dielectric material.

On the other hand, the liquid crystal lens 140 may also include two transparent substrates 148. The two transparent substrates 148 are located on opposite sides of the liquid crystal layer 142, and the liquid crystal layer 142, the electrode layer 144 and the electrode layer 146 are sandwiched between the two transparent substrates 148. The transparent substrate 148 may be, for example, glass or a similar transparent material, and the first strip electrode 145a and the second strip electrode 145b may be disposed on a transparent substrate 148 by a physical vapor deposition method (e.g., evaporation or sputtering).

Please refer to the partial stereoscopic diagram of the lens array layer 120 in FIG3 . The lens array layer 120 includes a plurality of parallel columnar lenses 122 , and the long axis of each columnar lens 122 extends along the second direction D2 . FIG4 shows a partial top view of the switchable stereoscopic display device 10 , which includes a liquid crystal lens 140 (shown in solid lines), a lens array layer 120 and a display module 100 .

FIG4 shows a partial top view of a switchable stereoscopic display device 10 of an embodiment of the present invention. As shown in FIG4, in some embodiments of the present invention, in order to avoid the formation of Moiré pattern, there is an angle θ1 between the first direction D1 extending from the electrode group G1 (or the electrode group G2) and the second direction D2 extending from the long axis of the cylindrical lens 122, and the angle θ1 is not 0°. In other words, the first direction D1 must not be parallel to the second direction D2. In some embodiments, the angle θ1 is a sharp angle and its range can fall between 0° and 50°, that is, the angle θ1 is greater than 0° and can be less than or equal to 50°, but the present invention is not limited thereto.

It is worth mentioning that, in order to further avoid the generation of moiré, in this embodiment, the scanning line (not shown) in the display module 100 may not be parallel to the first direction D1 or the second direction D2. Specifically, the scanning line in the display module 100 extends along the horizontal direction of FIG. 4, so the first direction D1 and the second direction D2 are not parallel to the horizontal direction of FIG. 4.

1 and 3 , each columnar lens 122 of the lens array layer 120 has a width W1, and each electrode group G1 (or electrode group G2) of the liquid crystal lens 140 has a pitch P1. In this embodiment, the pitch P1 of the electrode group G1 (or electrode group G2) may be smaller than the width W1 of the columnar lens 122. For example, the pitch P1 of the electrode group G1 may be between 40 μm and 150 μm, and the width W1 of the columnar lens 122 may be between 200 μm and 500 μm, but the present invention is not limited thereto. In other embodiments, the pitch P1 of the electrode group G1 (or electrode group G2) and the width W1 of the cylindrical lens 122 may also fall outside the above numerical range.

The switchable 3D display device 10 further includes a light-transmitting layer 160. The light-transmitting layer 160 is located on the lens array layer 120 and directly contacts the cylindrical lens 122. In this embodiment, the light-transmitting layer 160 covers the curved surface 122c (indicated in FIG. 3 ) of the cylindrical lens 122, and the refractive index of the light-transmitting layer 160 is less than the refractive index of the lens array layer 120. The material of the light-transmitting layer 160 may include, for example, UV glue or a similar light-transmitting material, and the refractive index thereof may range from 1.45 to 1.55. On the other hand, the refractive index of the lens array layer 120 may range from 1.6 to 1.7. Since the lens array layer 120 has a convex curved surface 122c, and the curved surface 122c faces the liquid crystal lens 140, a transparent layer 160 is disposed on the curved surface 122c to form a flat surface (not shown, such as the upper plane of the transparent layer 160 shown in FIG. 1), which helps to bond the lens array layer 120 and the liquid crystal lens 140, wherein the flat surface contacts one of the transparent substrates 148, such as the transparent substrate 148 located at the bottom in FIG. 1.

It is particularly worth mentioning that, when the display module 100 is not a liquid crystal display, the switchable stereoscopic display device 10 may further include a polarizer 180. For example, referring to FIG. 1 , the polarizer 180 is located above the liquid crystal lens 140, so that the liquid crystal lens 140 is located between the polarizer 180 and the lens array layer 120. However, the position of the polarizer 180 in the present invention is not limited thereto. Please refer to other embodiments shown in FIG. 5A and FIG. 5B (the display modules 100 in these embodiments are not liquid crystal displays). In the embodiment of FIG. 5A , the polarizer 180 may be located between the lens array layer 120 and the display module 100 , and in the embodiment of FIG. 5B , the polarizer 180 may be located between the lens array layer 120 and the liquid crystal lens 140 .

In summary, a liquid crystal lens is provided in a switchable stereoscopic display device, and the mode of the liquid crystal lens is switched for two-dimensional display and three-dimensional display. In the case of two-dimensional display, the liquid crystal material in the liquid crystal lens is driven to deflect to different degrees, thereby producing a lens effect. For example, in the above embodiment, the liquid crystal lens can present a lens effect of a parallel cylindrical convex lens, so that the light passing through the liquid crystal lens is deflected.

Since the image light emitted by the display module will produce focusing deflection after passing through the lens array layer, and this focusing deflection will cause the flat image to be displayed unevenly at different viewing angles. Therefore, when the switchable stereoscopic display device is in two-dimensional display, the image light is caused to produce divergent deflection through the liquid crystal lens to partially offset the above-mentioned focusing deflection, thereby improving the unevenness of the flat image. On the other hand, when the switchable stereoscopic display device is in three-dimensional display, the liquid crystal lens can be in transparent mode, and this transparent mode will not change the direction of the image light after passing through the lens array layer, so it will not affect the imaging of the three-dimensional picture. In this way, the quality of the two-dimensional display picture can be improved without affecting the quality of the three-dimensional display picture.

Although the embodiments of the present invention have been disclosed above, they are not intended to limit the embodiments of the present invention. Anyone with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, the protection scope of the embodiments of the present invention shall be subject to the scope of the attached patent application.

10: Switchable stereo display device

100: Display module

100s: Display surface

102: Color filter substrate

120: Lens array layer

120i: light-entering surface

122: cylindrical lens

122c: Surface

140: Liquid crystal lens

140s: Surface

142M: Liquid crystal molecules

144,146:Electrode layer

148: Translucent substrate

160: Translucent layer

180: Polarizer

A1: Center axis

d1: first spacing

d2: Second spacing

G1: Electrode group

M1: Image light

P1: Distance

W1: Width

Claims (7)

A switchable stereoscopic display device comprises: a display module having a display surface, wherein the display module emits an image light from the display surface; a lens array layer, disposed above the display surface and comprising a plurality of parallel columnar lenses; and a liquid crystal lens, disposed above the display surface and overlapping the lens array layer, wherein the liquid crystal lens and the lens array layer are both located on the transmission path of the image light, and the liquid crystal lens comprises; a liquid crystal layer; two transparent substrates, respectively located on opposite sides of the liquid crystal layer; Two electrode layers are respectively located on opposite sides of the liquid crystal layer, wherein each of the electrode layers comprises: A plurality of parallel electrode groups, and each of the electrode groups extends along a first direction, wherein the long axis of each of the columnar lenses extends along a second direction, and there is an angle between the first direction and the second direction, and the angle is not 0°, wherein the liquid crystal layer and the two electrode layers are sandwiched between the two transparent substrates, wherein the scanning lines in the display module are neither parallel to the first direction nor parallel to the second direction; and A light-transmitting layer is located on the lens array layer and directly contacts the columnar lenses to form a flat surface that contacts one of the two light-transmitting substrates, wherein the refractive index of the light-transmitting layer is less than the refractive index of the lens array layer; wherein a surface of the liquid crystal lens and a light-incident surface of the lens array layer have a first distance, and a surface of the liquid crystal lens and the display surface of the display module have a second distance; when the switchable stereoscopic display device performs a two-dimensional image display, the liquid crystal lens is in a lens mode and has a focal length, wherein the range of the focal length falls between the first distance and the second distance, so that the liquid crystal lens in the lens mode is used to diverge the image light; When the switchable stereoscopic display device displays three-dimensional images, the liquid crystal lens is in a transparent mode and does not deflect the image light. After passing through the liquid crystal lens, the image light will not deflect away from the central axis of the cylindrical lens, so that the image light cannot diverge. A switchable three-dimensional display device as described in claim 1, wherein the angle is greater than 0° and less than or equal to 50°. A switchable three-dimensional display device as described in claim 1, wherein each of the cylindrical lenses has a width, and each of the electrode groups has a perimeter, wherein the perimeter is smaller than the width. The switchable three-dimensional display device as described in claim 1, wherein the lens array layer is located between the liquid crystal lens and the display module. The switchable stereoscopic display device as described in claim 4 further comprises: A polarizer located between the lens array layer and the display module. The switchable stereoscopic display device as described in claim 4 further comprises: A polarizer located between the lens array layer and the liquid crystal lens. The switchable three-dimensional display device as described in claim 1, wherein the liquid crystal lens is located between the lens array layer and the display module.

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