Embodiments of the present disclosure provide a display panel and a display device. The display panel includes a plurality of sub-pixels each comprising a display unit. The display unit includes a first electrode, a second electrode and a liquid crystal layer. A first black matrix pattern is disposed at a side of the liquid crystal layer facing the first electrode and a second black matrix pattern is disposed at a side of the liquid crystal layer facing the second electrode, the second black matrix pattern having an opening therein, the first black matrix pattern being disposed at a position corresponding to the opening.

A cholesteric liquid crystal writing board, which can display a writing track, includes a cholesteric liquid crystal device, an optical layer, a photo-sensing array and a voltage control circuit. The cholesteric liquid crystal device includes plural liquid crystal control areas. The optical layer has plural optical openings. The photo-sensing array includes plural photo sensors arranged in an array. The photo sensors are disposed corresponding to the optical openings. One of the photo sensors senses a luminous flux change and generates an erasing signal accordingly. The voltage control circuit receives the erasing signal and outputs a voltage signal accordingly to the liquid crystal control areas corresponding to the photo sensors having the luminous flux change, such that a part or all of cholesteric liquid crystals corresponding to the liquid crystal control areas are morphologically changed so as to clear a part or all of the writing trace.

A display panel and a display device are provided. The display panel includes a first base substrate; a second base substrate opposite to the first base substrate; a liquid crystal layer between the first and second base substrates; a first alignment film at a side of the first base substrate facing the liquid crystal layer; a second alignment film at a side of the second base substrate facing the liquid crystal layer; a polarizer at a side of the first base substrate away from the liquid crystal layer; and a quarter-wave plate between the polarizer and the first base substrate. An angle between a center line of an included angle between the first alignment direction of the first alignment film and the second alignment direction of the second alignment film and a slow axis of the quarter-wave plate is in a range from 75 to 105 degrees.

A liquid crystal device and the use thereof are provided. The liquid crystal device has an advantage in terms of power consumption since a normally transparent mode may be realized in a state in which an external electric field is not applied, and can exhibit an excellent light blocking characteristic when an external electric field is applied.

A display device includes a backlight module, a liquid crystal layer, a lower polarizer, an upper polarizer, and a retardation layer. The liquid crystal layer is disposed on a lighting side of the backlight module while the lower polarizer is disposed between the liquid crystal layer and the backlight module. The upper polarizer is disposed on a side of the liquid crystal layer opposite to the lower polarizer, and the retardation layer is between the upper and lower polarizers. The retardation layer has a retardation area that may modulates the light passing through the lower polarizer and make the light passes through the upper polarizer.

A cholesteric liquid crystal writing board, which can display a writing track, includes a cholesteric liquid crystal device, an optical layer, a photo-sensing array and a voltage control circuit. The cholesteric liquid crystal device includes plural liquid crystal control areas. The optical layer has plural optical openings. The photo-sensing array includes plural photo sensors arranged in an array. The photo sensors are disposed corresponding to the optical openings. One of the photo sensors senses a luminous flux change and generates an erasing signal accordingly. The voltage control circuit receives the erasing signal and outputs a voltage signal accordingly to the liquid crystal control areas corresponding to the photo sensors having the luminous flux change, such that a part or all of cholesteric liquid crystals corresponding to the liquid crystal control areas are morphologically changed so as to clear a part or all of the writing trace.

The present disclosure provides a liquid crystal grating, a method for driving the liquid crystal grating, and a display device. In the embodiments of the present disclosure, by applying the second voltage and the third voltage that are mutually inverted with respect to the common electrode voltage, the situation in which a single phase voltage is applied to all grating electrodes corresponding to the power-on optical state can be avoided. Due to the capacitance of liquid crystal, the influence of the second voltage on the common electrode voltage and the influence of the third voltage on the common electrode voltage cancel each other out. Therefore, the fluctuation of the common electrode voltage caused by the capacitance of liquid crystal can be effectively reduced or eliminated, thereby avoiding the failure of the liquid crystal grating.

The multi-layer display system may include a plurality of display panels arranged in an overlapping manner, a backlight configured to provide light to the plurality of display panels, and a processing system. Each of the display panels may include an array of pixels. One or more of the display panels may be provided with a black mask and one or more of the display panels may be provided without a black mask to increase the transmissivity of the multi-layer display. The processing system may be configured to control the display of different content on the plurality of display panels.

Provided is a display device that can increase the quantity of light transmitted to a front surface side by improving the utilization efficiency of backlight and that can reduce stress experienced by a viewer by reducing glare on a back surface side. Not only a first polarization wave emitted from a light guide plate 20 to a display surface side but also a first polarization wave included in light converted, by a polymer-dispersed liquid-crystal element 60 in a scattering mode from a first polarization wave and a second polarization wave emitted to a rear surface side is converted to a second polarization wave by a liquid-crystal panel 30 and is transmitted to the front surface side. Thus, the utilization efficiency of the light emitted from the light guide plate 20 improves. In addition, a portion of the first polarization wave and the second polarization wave emitted from the light guide plate 20 to the rear surface side is reflected by a reflective polarization plate 53 to the display surface side, and thus the quantity of light of the first polarization wave transmitted to the back surface side is reduced.

A display cluster having an active state and an inactive state includes a front cover with an outer surface facing outwardly toward a viewer and an inner surface opposite the outer surface. An active display region with a display screen to generate an image and a first backlight may be surrounded by a peripheral region including a second backlight. One or more of the backlights may illuminate with the display cluster in the active state. A partial mirror may be disposed on the inner surface of the front cover to allow the display light from the active display region to pass outwardly therethrough and to block incident light from passing therethrough. The partial mirror may prevent reflections from one or more structures located therebeyond, away from the viewer, and may thereby present a uniform appearance between the active display region and the peripheral region with the display cluster in the inactive state.