LIQUID CRYSTAL DISPLAY DEVICE

Abstract

A liquid crystal display device includes a liquid crystal modulation element including a first electrode, a second electrode, and a liquid crystal layer, a potential difference providing unit that provides a potential difference between the first electrode and the second electrode, and an illumination optical system that illuminates the liquid crystal modulation element by using light from a light source. The liquid crystal display device includes a charge adjusting mode for reducing the intensity of an electric field generated by electric charge stored between the liquid crystal layer and at least one of the first electrode and the second electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the operation of a reflective liquid crystal modulation element, according to an aspect of the present invention.

FIG. 2 is a schematic diagram illustrating a liquid crystal modulation element, according to an aspect of the present invention.

FIGS. 3A and 3B illustrate a potential difference across a liquid crystal layer under a normal condition and that with the occurrence of flickering, respectively, according to an aspect of the present invention.

FIG. 4 illustrates a phenomenon in which charging occurs on the surface of the liquid crystal layer of a reflective liquid crystal modulation element, according to an aspect of the present invention.

FIG. 5 illustrates a technique for controlling the amount of charging on the surface of the liquid crystal layer of a reflective liquid crystal modulation element according to an embodiment of the present invention.

FIG. 6 is a graph as a result of a test when charging occurs on the surface of the liquid crystal layer of a reflective liquid crystal modulation element, according to an aspect of the present invention.

FIG. 7 is a graph as a result of a test when a technique for controlling the amount of charging that has occurred on the surface of the liquid crystal layer of a reflective liquid crystal modulation element is used according to an embodiment of the present invention.

FIG. 8 is a schematic view illustrating a projection display device using reflective liquid crystal modulation elements according to an embodiment of the present invention.

FIG. 9 is a flowchart illustrating a procedure for performing a charge removing mode according to an embodiment of the present invention.

Claims

1. A liquid crystal display device comprising: a liquid crystal modulation element including a first electrode, a second electrode, and a liquid crystal layer disposed between the first electrode and the second electrode;a potential difference providing unit that provides a potential difference between the first electrode and the second electrode; andan illumination optical system that illuminates the liquid crystal modulation element,wherein the liquid crystal display device includes a charge adjusting mode for reducing the intensity of an electric field generated by electric charge stored between the liquid crystal layer and at least one of the first electrode and the second electrode.

2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a first mode and a second mode, the liquid crystal display device arranged so that when operated in the first mode, a positive voltage and a negative voltage are alternately applied to the liquid crystal layer in every drive cycle by using the potential difference providing unit while illuminating the liquid crystal modulation element by using the illumination optical system and when operated in the second mode, the liquid crystal display device is the charge adjusting mode in which a direct current voltage is applied to the liquid crystal layer for a period longer than the drive cycle by using the potential difference providing unit while illuminating the liquid crystal modulation element by using the illumination optical system.

3. The liquid crystal display device according to claim 1, wherein the direct current voltage applied to the liquid crystal layer in the charge adjusting mode is greater than 200 mV.

4. The liquid crystal display device according to claim 1, wherein the charge adjusting mode is executed during at least one of a start sequence for starting the liquid crystal display device and a stop sequence for stopping the liquid crystal display device.

5. The liquid crystal display device according to claim 1, wherein a time for which the charge adjusting mode is continued is determined based on at least one of an accumulative operation time of the liquid crystal modulation element, an operation environment of the liquid crystal modulation element, and a wavelength of light applied to the liquid crystal modulation element.

6. The liquid crystal display device according to claim 1, further comprising an alarm unit that issues an alarm on the basis of a load parameter which is determined based on at least one of an accumulative operation time of the liquid crystal modulation element, an operation temperature environment of the liquid crystal modulation element, and a quantity or a wavelength of light applied to the liquid crystal modulation element.

7. The liquid crystal display device according to claim 1, wherein the drive cycle is 1/60 seconds or shorter.

8. The liquid crystal display device according to claim 1, wherein a time for which the charge adjusting mode is continued is one second or longer.

9. The liquid crystal display device according to claim 1, wherein a material for the first electrode is different from a material for the second electrode.

10. The liquid crystal display device according to claim 1, wherein a Fermi level of the first electrode is different from a Fermi level of the second electrode.

11. The liquid crystal display device according to claim 1, wherein a thin film composed of an insulating material is disposed between the liquid crystal layer and each of the first electrode and the second electrode.

12. The liquid crystal display device according to claim 1, wherein the liquid crystal modulation element is a reflective liquid crystal modulation element, and the first electrode and the second electrode are a transparent electrode and a mirror electrode, respectively.

13. A liquid crystal display device comprising: first, second, and third liquid crystal modulation elements corresponding to a first color, a second color, and a third color, respectively, each of the liquid crystal modulation elements including a first electrode, a second electrode, and a liquid crystal layer disposed between the first electrode and the second electrode;first, second, and third potential difference providing units that provide potential differences between the first electrodes and the second electrodes of the first, second, and third liquid crystal modulation elements, respectively;an illumination optical system that illuminates the first, second, and third liquid crystal modulation elements; anda projection optical system that projects image light components from the first, second, and third liquid crystal modulation elements,wherein the liquid crystal display device is operated in a first mode in which a positive voltage and a negative voltage are alternately applied to the liquid crystal layer of each of the first, second, and third liquid crystal modulation elements in every drive cycle by using the potential difference providing unit while illuminating each of the first, second, and third liquid crystal modulation elements by using the illumination optical system and in a charge adjusting mode in which a direct current voltage is applied to the liquid crystal layer of each of the first, second, and third liquid crystal modulation elements for a period longer than the drive cycle by using the potential difference providing unit while applying the light from the light source to each of the first, second, and third liquid crystal modulation elements by using the illumination optical system.

14. The liquid crystal display device according to claim 13, wherein a time for which the charge adjusting mode is continued for each of the first, second, and third liquid crystal modulation elements is determined based on at least one of an accumulative operation time of the first liquid crystal modulation element, an operation temperature environment of the first liquid crystal modulation element, and a quantity or a wavelength of light applied to the first liquid crystal modulation element.

15. The liquid crystal display device according to claim 13, further comprising an alarm unit that issues an alarm on the basis of a load parameter which is determined based on at least one of an accumulative operation time of the first liquid crystal modulation element, an operation environment of the first liquid crystal modulation element, and a wavelength of light applied to the first liquid crystal modulation element.

16. The liquid crystal display device according to claim 13, further comprising an alarm unit that issues an alarm on the basis of an output from a sensor that receives at least part of light emitted from the first liquid crystal modulation element.

17. The liquid crystal display device according to claim 13, wherein a time for which the charge adjusting mode is continued for the first liquid crystal modulation element is different from a time for which the charge adjusting mode is continued for the second liquid crystal modulation element.