TWI847324B - Display device - Google Patents

Abstract

A display device including a display panel, a first cholesteric liquid crystal layer, a quarter-wave plate and a first switchable polarizer, which are sequentially stacked, is provided. The first cholesteric liquid crystal layer is configured to reflect one of a left-circularly polarized light or a right-circularly polarized light. When the polarization property of the first switchable polarizer is activated, the first switchable polarizer is a linear polarizer and has a first absorbing axis.

Description

Display device

The present invention relates to a display device.

In recent years, display devices have been designed with special decorative appearances to improve variability, mainly by using reflective cholesterol liquid crystals to reflect light of a specific polarization state, so that the cholesterol liquid crystal pattern is visible. However, in order to achieve the purpose of switching the pattern on or off, multiple layers are often required, making the stacking structure complex. If multiple patterns are used and switched between multiple patterns, the complexity of the stacking structure will be even higher.

The present invention provides a display device that can switch patterns on or off, has a simple stacking structure, and can switch multiple patterns.

According to an embodiment of the present invention, a display device is provided, comprising a display panel, a first cholesterol liquid crystal layer, a quarter wave plate, and a first switching polarizer which are sequentially stacked. The first cholesterol liquid crystal layer is configured to reflect one of left-handed circular polarization or right-handed circular polarization. When the first switching polarizer turns on polarization, the first switching polarizer is a linear polarizer and has a first absorption axis.

Based on the above, the display device provided by the embodiment of the present invention changes the polarization state of light by means of a switchable polarizer, so that the display device can simply switch the cholesterol liquid crystal pattern to be visible or invisible. Compared with the conventional art where the polarization of the polarizer cannot be turned off, multiple optical elements (such as electrically controlled liquid crystal elements) used to control the phase (polarization state) can be omitted, thereby reducing the size of the display device.

In order to make the above features and advantages of the present invention more clearly understood, embodiments are specifically cited below and described in detail with reference to the accompanying drawings.

1A to 1C, the display device 100 includes a display panel 10, a first cholesterol liquid crystal layer 102, a quarter wave plate 20, and a first switching polarizer 101 which are sequentially stacked. The first cholesterol liquid crystal layer 102 has a pattern and is configured to reflect right-handed circular polarization. When the first switching polarizer 101 turns on polarization, the first switching polarizer 101 is a linear polarizer and has a first absorption axis, which is parallel to the X direction.

Referring to FIG1B , when the first switchable polarizer 101 turns off polarization, the electric field of the ambient light C1 without a specific polarization state can penetrate the first switchable polarizer 101 in all directions, wherein the electric field of the ambient light C1 is represented by the electric field component in the X direction and the electric field component in the Y direction as shown in FIG1B . From another perspective, the ambient light C1 can be regarded as a combination of linear polarization in the X direction and linear polarization in the Y direction.

By properly configuring the optical axis direction of the quarter-wave plate 20, the linear polarized light in the X direction can be transformed into right-handed circularly polarized light after passing through the quarter-wave plate 20 (in FIG. 1B and other subsequent figures, right-handed circularly polarized light is represented by a clockwise arrow), and the linear polarized light in the Y direction can be transformed into left-handed circularly polarized light after passing through the quarter-wave plate 20 (in FIG. 1B and other subsequent figures, left-handed circularly polarized light is represented by a counterclockwise arrow).

Since the first cholesterol liquid crystal layer 102 is configured to reflect right-handed circularly polarized light, the left-handed circularly polarized light in the ambient light C1 will penetrate the first cholesterol liquid crystal layer 102. In FIG1B , the right-handed circularly polarized light reflected by the first cholesterol liquid crystal layer 102 is marked as reflected pattern light C2. Specifically, the first cholesterol liquid crystal layer 102 has cholesterol liquid crystals and has a decorative pattern, such as wood grain. Cholesterol liquid crystal is a liquid crystal molecule having the properties of Bragg reflection and bi-stable, which can reflect incident light with a wavelength equivalent to its helical pitch and the same optical rotation, thereby presenting its decorative pattern. In this embodiment, right-handed circularly polarized light can be reflected by the first cholesterol liquid crystal layer 102, so the reflected pattern light C2 has the decorative pattern information of the first cholesterol liquid crystal layer 102. The reflected pattern light C2 is transformed into linear polarized light in the X direction after passing through the quarter wave plate 20. The linear polarized light in the X direction can pass through the first switchable polarizer 101, so that the decorative pattern of the first cholesterol liquid crystal layer 102 is visible.

In one embodiment, the display panel 10 in FIG1B is closed, and the user can only see the decorative pattern of the first cholesterol liquid crystal layer 102. In one embodiment, the display panel 10 in FIG1B is turned on to provide a display image, and the user can see the decorative pattern of the first cholesterol liquid crystal layer 102 and the display image of the display panel 10 at the same time.

Referring to FIG. 1C , when the first switchable polarizer 101 turns on polarization, since its first absorption axis is parallel to the X direction, only linear polarization in the Y direction can penetrate the first switchable polarizer 101. The linear polarization in the Y direction is transformed into left-handed circular polarization after penetrating the quarter-wave plate 20, and the left-handed circular polarization penetrates the first cholesterol liquid crystal layer 102. The user will not see the decorative pattern of the first cholesterol liquid crystal layer 102.

In one embodiment, the display panel 10 in FIG. 1C is a self-luminous display panel, such as a micro-luminescent diode display panel, an organic light-emitting diode display panel or other suitable self-luminous display panel. When the display panel 10 is turned on, it outputs image light to provide a display image. The display panel 10 can increase the output brightness of the wavelength corresponding to the pitch of the cholesterol liquid crystal of the first cholesterol liquid crystal layer 102 in the image light to compensate for the portion of the image light with the above wavelength reflected back to the display panel 10 by the first cholesterol liquid crystal layer 102, thereby avoiding color deviation.

In the embodiments shown in FIGS. 1A to 1C , the first cholesterol liquid crystal layer 102 is configured to reflect right-handed circularly polarized light, and the first absorption axis of the first switchable polarizer 101 is parallel to the X direction. However, the present invention is not limited thereto. In one embodiment, the first cholesterol liquid crystal layer 102 is configured to reflect left-handed circularly polarized light, and the first absorption axis of the first switchable polarizer 101 is parallel to the Y direction. In this case, the reflected pattern light C2 in FIG. 1B is left-handed circularly polarized light, which is formed into linear polarized light in the Y direction after passing through the quarter-wave plate 20, and can also pass through the first switchable polarizer 101, so that the decorative pattern of the first cholesterol liquid crystal layer 102 is visible. In FIG. 1C , the linearly polarized light in the X direction passes through the first switchable polarizer 101 , which becomes right-handed circularly polarized light after passing through the quarter-wave plate 20 , and then passes through the first cholesterol liquid crystal layer 102 , and the decorative pattern of the first cholesterol liquid crystal layer 102 is also not visible.

In one embodiment, the first switchable polarizer 101 includes liquid crystal molecules doped with dyes. The polarization of the first switchable polarizer 101 can be turned on or off by electrical control, but the present invention is not limited thereto. It should be noted that in the prior art, the polarization of the polarizer cannot be turned off, so it is necessary to add other elements, such as electrically controlled liquid crystal elements, to change the phase (polarization state) of light as a means of switching whether the pattern of the cholesterol liquid crystal layer is visible, but this causes the volume of the display device to be too large. Since the polarization of the first switchable polarizer 101 of the embodiment of the present invention can be turned on or off, the display device 100 can simply switch the pattern of the first cholesterol liquid crystal layer 102 to be visible or invisible, and multiple optical elements are omitted, thereby reducing the size of the display device 100.

2A to 2C , the display device 200 includes a display panel 10, a second cholesterol liquid crystal layer 202, a first cholesterol liquid crystal layer 102, a quarter wave plate 20, a second switching polarizer 201, and a first switching polarizer 101, which are sequentially stacked. As shown in FIG. 2A , the first cholesterol liquid crystal layer 102 and the second cholesterol liquid crystal layer 202 are disposed between the display panel 10 and the quarter wave plate 20, and the second switching polarizer 201 is disposed between the quarter wave plate 20 and the first switching polarizer 101.

In the present embodiment, the first cholesterol liquid crystal layer 102 has a pattern and is configured to reflect right-handed circularly polarized light; the second cholesterol liquid crystal layer 202 also has a pattern, and it is different from the pattern of the first cholesterol liquid crystal layer 102, and the second cholesterol liquid crystal layer 202 is configured to reflect left-handed circularly polarized light; when the first switching polarizer 101 turns on the polarization, the first switching polarizer 101 is a linear polarizer and has a first absorption axis, and the first absorption axis is parallel to the X direction; when the second switching polarizer 201 turns on the polarization, the second switching polarizer 201 is a linear polarizer and has a second absorption axis, and the second absorption axis is parallel to the Y direction.

Referring to FIG. 2B , in this embodiment, the first switchable polarizer 101 turns off polarization, and the second switchable polarizer 201 turns on polarization. The electric fields of the ambient light C1 without a specific polarization state can all penetrate the first switchable polarizer 101, but only the linear polarization in the X direction can penetrate the second switchable polarizer 201. The linear polarization in the X direction is transformed into right-handed circular polarization after penetrating the quarter-wave plate 20. Since the right-handed circular polarization can be reflected by the first cholesterol liquid crystal layer 102, the reflected pattern light C2 has the decorative pattern information of the first cholesterol liquid crystal layer 102. The reflected pattern light C2 is transformed into linear polarization in the X direction after penetrating the quarter-wave plate 20. The linear polarized light in the X direction can sequentially penetrate the second switchable polarizer 201 and the first switchable polarizer 101, so that the decorative pattern of the first cholesterol liquid crystal layer 102 is visible, and the decorative pattern of the second cholesterol liquid crystal layer 202 is invisible.

In one embodiment, the display panel 10 in FIG2B is closed, and the user can only see the decorative pattern of the first cholesterol liquid crystal layer 102. In one embodiment, the display panel 10 in FIG2B is opened to provide a display image, and the user can see the decorative pattern of the first cholesterol liquid crystal layer 102 and the display image of the display panel 10 at the same time.

Referring to FIG. 2C , in this embodiment, the first switchable polarizer 101 turns on the polarization, and the second switchable polarizer 201 turns off the polarization. In the ambient light C1 without a specific polarization state, only the linear polarization in the Y direction can penetrate the first switchable polarizer 101 and then penetrate the second switchable polarizer 201. The linear polarization in the Y direction is transformed into left-handed circular polarization after penetrating the quarter-wave plate 20, and the left-handed circular polarization penetrates the first cholesterol liquid crystal layer 102. Since the left-handed circular polarization can be reflected by the second cholesterol liquid crystal layer 202, the reflected pattern light C3 has the decorative pattern information of the second cholesterol liquid crystal layer 202. The reflected pattern light C3 can penetrate the first cholesterol liquid crystal layer 102 and remain as left-handed circular polarization. The left-handed circularly polarized light is transformed into linearly polarized light in the Y direction after passing through the quarter wave plate 20. The linearly polarized light in the Y direction can sequentially pass through the second switching polarizer 201 and the first switching polarizer 101, so that the decorative pattern of the second cholesterol liquid crystal layer 202 is visible, and the decorative pattern of the first cholesterol liquid crystal layer 102 is invisible.

In one embodiment, the display panel 10 in FIG2C is closed, and the user can only see the decorative pattern of the second cholesterol liquid crystal layer 202. In one embodiment, the display panel 10 in FIG2C is opened to provide a display image, and the user can see the decorative pattern of the second cholesterol liquid crystal layer 202 and the display image of the display panel 10 at the same time.

In one embodiment, the display panel 10 is a self-luminous display panel, such as a micro-luminescent diode display panel, an organic light-emitting diode display panel or other suitable self-luminous display panel. When the display panel 10 is turned on, it outputs image light to provide a display image. The display panel 10 can increase the output brightness of the image light at a wavelength corresponding to the pitch of the cholesterol liquid crystal of the first cholesterol liquid crystal layer 102, and increase the output brightness of the image light at a wavelength corresponding to the pitch of the cholesterol liquid crystal of the second cholesterol liquid crystal layer 202, so as to compensate for the image light with the above wavelengths being reflected back to the display panel 10 by the first cholesterol liquid crystal layer 102 and the second cholesterol liquid crystal layer 202, thereby avoiding color deviation.

In one embodiment, the first switching polarizer 101 and the second switching polarizer 201 both include liquid crystal molecules doped with dyes. The polarization of the first switching polarizer 101 and the second switching polarizer 201 can be turned on or off by electrical control, but the present invention is not limited thereto. It should be noted that in the prior art, the polarization of the polarizer cannot be turned off, so it is necessary to add other elements, such as electrically controlled liquid crystal elements, to change the phase (polarization state) of light as a means of switching whether the pattern of the cholesterol liquid crystal layer is visible, but this causes the volume of the display device to be too large. Since the polarization of the first switchable polarizer 101 and the second switchable polarizer 201 of the embodiment of the present invention can be turned on or off, the display device 200 can be simply switched to display the pattern of the first cholesterol liquid crystal layer 102 or the pattern of the second cholesterol liquid crystal layer 202, and multiple optical elements are omitted, thereby reducing the size of the display device 200.

In summary, the display device provided by the embodiment of the present invention changes the polarization state of light by using a switchable polarizer, so that the display device can simply switch the pattern of cholesterol liquid crystal to be visible or invisible, or switch to display different decorative patterns. Compared with the conventional art where the polarization of the polarizer cannot be turned off, multiple optical elements used to control the phase (polarization state) can be omitted, and the volume of the display device can be reduced.

10: Display panel 20: Quarter wave plate 100, 200: Display device 101: First switching polarizer 201: Second switching polarizer 102: First cholesterol liquid crystal layer 202: Second cholesterol liquid crystal layer C1: Ambient light C2, C3: Reflected pattern light X, Y, Z: Direction

FIG1A is a schematic diagram of a display device according to an embodiment of the present invention. FIG1B is a schematic diagram of the optical mechanism of the display device shown in FIG1A. FIG1C is a schematic diagram of the optical mechanism of the display device shown in FIG1A. FIG2A is a schematic diagram of a display device according to an embodiment of the present invention. FIG2B is a schematic diagram of the optical mechanism of the display device shown in FIG2A. FIG2C is a schematic diagram of the optical mechanism of the display device shown in FIG2A.

10: Display panel 20: Quarter wave plate 100: Display device 101: First switching polarizer 102: First cholesterol liquid crystal layer C1: Ambient light C2: Reflected pattern light X, Y, Z: Direction

Claims (10)

A display device includes a display panel, a first cholesterol liquid crystal layer, a quarter wave plate, a first switching polarizer, a second cholesterol liquid crystal layer and a second switching polarizer which are sequentially stacked, wherein the second cholesterol liquid crystal layer is arranged between the display panel and the quarter wave plate, wherein the second switching polarizer is arranged between the quarter wave plate and the first switching polarizer, wherein the first cholesterol liquid crystal layer is arranged to reflect one of left-handed circular polarization or right-handed circular polarization, and when the first switching polarizer turns on polarization, the first switching polarizer is a linear polarizer and has a first absorption axis. A display device as described in claim 1, wherein the display panel is a self-luminous display panel. A display device as described in claim 2, wherein the display panel increases the output brightness of the color light corresponding to the pitch of the first cholesterol liquid crystal layer. A display device as described in claim 1, wherein the second cholesterol liquid crystal layer is configured to reflect the other of the left-handed circularly polarized light or the right-handed circularly polarized light. A display device as described in claim 1, wherein when the second switchable polarizer turns on polarization, the second switchable polarizer is a linear polarizer and has a second absorption axis. A display device as described in claim 5, wherein the second absorption axis is perpendicular to the first absorption axis. A display device as described in claim 6, wherein when one of the first switching polarizer and the second switching polarizer turns on polarization and the other of the first switching polarizer and the second switching polarizer turns off polarization, the pattern of one of the first cholesterol liquid crystal layer and the second cholesterol liquid crystal layer is visible, and the pattern of the other of the first cholesterol liquid crystal layer and the second cholesterol liquid crystal layer is invisible. A display device as described in claim 1, wherein the display panel is a self-luminous display panel. In the display device as described in claim 8, the display panel increases the output brightness of the color light corresponding to the pitch of the first cholesterol liquid crystal layer, and the display panel increases the output brightness of the color light corresponding to the pitch of the second cholesterol liquid crystal layer. A display device as described in claim 1, wherein the first switchable polarizer and the second switchable polarizer include liquid crystal molecules doped with dyes.

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