Method and apparatus for driving liquid crystal display having memory effect

Claim 2

A driving method on a display device, said method comprising: a first step of presenting a display by refresh scanning, on the basis of image information, on a liquid crystal display device which has a liquid crystal and scanning and information electrodes arranged in a matrix form and in which a plurality of pixels having a memory effect are provided; and a second step of presenting a display by non-refresh scanning without substantially changing the image information, wherein a non-zero voltage signal to fluctuate a transmission light amount of the plurality of pixels is applied to the information electrodes during said second step, and wherein in the first step a scanning selection signal is successively supplied to the scanning electrodes, and in the second step, the scanning selection signal is not supplied to the scanning electrodes.

Claim 16

A driving method according to claim 1, wherein the signal to fluctuate the transmission light amount is an A.C. pulse signal.

Claim 17

A driving method according to claim 1, wherein said refresh scanning provides all scanning electrodes with a reference voltage, and provides all information electrodes with an A.C. pulse signal.

Claim 20

A display apparatus comprising: a liquid crystal display panel in which pixels are constructed by a group of scanning electrodes and a group of information electrodes in a matrix form; a liquid crystal which is arranged in said liquid crystal display panel and is driven by an electric field applied through said group of scanning electrodes and said group of information electrodes; an image information storing circuit to store image information to be displayed by said liquid crystal display panel; a change detection circuit to detect whether the image information stored in said image information storing circuit has changed; first driving means for applying a scanning signal to said group of scanning electrodes and applying an information signal to said group of information electrodes on the basis of the image information stored in said image information storing circuit; and second driving means for applying a waveform which produces, on said liquid crystal, a luminance that is almost equal to a luminance produced in a scanning non-selection period by said first driving means to said liquid crystal display panel while maintaining the display state on said display panel by application of the electric field to the group of scanning electrodes and the group of information electrodes in accordance with the result of the detection by said change detection circuit.

Claim 21

A display apparatus comprising: a liquid crystal display panel in which pixels are constructed by a group of scanning electrodes and a group of information electrodes in a matrix form; a liquid crystal which is arranged in said liquid crystal display panel and is driven by an electric field applied through said group of scanning electrodes and said group of information electrodes; an image information storing circuit to store image information to be displayed by said liquid crystal display panel; a change detection circuit to detect whether the image information stored in said image information storing circuit has changed; first driving means for applying a scanning signal to said group of scanning electrodes and applying an information signal to said group of information electrodes on the basis of the image information stored in said image information storing circuit; and second driving means for applying a waveform which produces, on said liquid crystal, a luminance that is almost equal to a luminance produced in a scanning non-selection period by said first driving means to said liquid crystal display panel while maintaining the display state on said display panel by application of the electric field to the group of scanning electrodes and the group of information electrodes in accordance with the result of the detection by said change detection circuit.

Claim 22

An apparatus according to claim 16, wherein a ratio between the luminance in said scanning non-selection period of time by said first driving means and the luminance by said second driving means lies within a range from 0.95 to 1.05.

Claim 23

An apparatus according to claim 16, wherein said liquid crystal is a ferroelectric liquid crystal.

Claim 24

A display apparatus comprising: a liquid crystal display panel in which pixels are constructed by a group of scanning electrodes and a group of information electrodes in a matrix form, and a liquid crystal, said panel being driven by an electric field which is applied through the group of scanning electrodes and the group of information electrodes; an image information storing circuit to store image information to be displayed by said liquid crystal display panel; driving means for applying a scanning signal to the group of scanning electrodes and applying an information signal to the group of information electrodes on the basis of the image information stored in said image information storing circuit; memory display means for holding display contents on the liquid crystal display panel without applying any voltage to the liquid crystal; a change detection circuit to detect whether the image information stored in said image information storing circuit has changed; and a driving control circuit for switching a display mode of said liquid crystal between an ordinary display mode to be executed by said driving means and a memory display mode to be executed by said memory display means and for gradually changing a waveform that is applied to the liquid crystal after a predetermined switching period of time when said display mode is switched wherein, during a time period for gradually changing a waveform, the display contents is not changed.

Claim 25

A display apparatus comprising: a liquid crystal display panel in which pixels are constructed by a group of scanning electrodes and a group of information electrodes in a matrix form, and a liquid crystal, said panel being driven by an electric field which is applied through the group of scanning electrodes and the group of information electrodes; an image information storing circuit to store image information to be displayed by said liquid crystal display panel; driving means for applying a scanning signal to the group of scanning electrodes and applying an information signal to the group of information electrodes on the basis of the image information stored in said image information storing circuit; memory display means for holding display contents on the liquid crystal display panel without applying any voltage to the liquid crystal; a change detection circuit to detect whether the image information stored in said image information storing circuit has changed; and a driving control circuit for switching a display mode of said liquid crystal between an ordinary display mode to be executed by said driving means and a memory display mode to be executed by said memory display means and for gradually changing a waveform that is applied to the liquid crystal after a predetermined switching period of time when said display mode is switched wherein, during a time period for gradually changing a waveform, the display contents is not changed.

Claim 26

An apparatus according to claim 19, wherein said driving control circuit changes an amplitude of a driving waveform in said switching period of time.

Claim 27

An apparatus according to claim 19, wherein said driving control circuit changes a pulse width of a driving waveform in said switching period of time.

Claim 28

An apparatus according to claim 19, wherein said liquid crystal is a ferroelectric liquid crystal.

Claim 29

A driving device of a display device with a memory effect, comprising: means for performing one of first and second modes, wherein the first mode comprises successively applying a scanning selection signal to a scanning electrode of the display device and applying an information signal to an information electrode of the display device to perform an image display wherein the image can be rewritten, and the second mode comprises performing the image display using the memory effect without applying the scanning selection signal no the scanning electrode of the display device, wherein rewriting of the image is not performed; and means for switching the display device between the first and second modes, wherein, during the second mode, a non-zero voltage of a level which does not cause image rewriting is applied to the information electrode of the display device.

Claim 30

A driving device of a display device with a memory effect, comprising: means for performing one of first and second modes, wherein the first mode comprises successively applying a scanning selection signal to a scanning electrode of the display device and applying an information signal to an information electrode of the display device to perform an image display wherein the image can be rewritten, and the second mode comprises performing the image display using the memory effect without applying the scanning selection signal no the scanning electrode of the display device, wherein rewriting of the image is not performed; and means for switching the display device between the first and second modes, wherein, during the second mode, a non-zero voltage of a level which does not cause image rewriting is applied to the information electrode of the display device.

Claim 31

A driving device of a display device with a memory effect, comprising: means for performing one of first, second and third modes, wherein the first mode comprises successively applying a scanning selection signal to a scanning electrode of the display device and applying an information signal to an information electrode of the display device to perform an image display wherein the image can be rewritten, the second mode comprises performing the image display using the memory effect without applying the scanning selection signal to the scanning electrode of the display device, wherein rewriting of the image is not performed, and the third mode comprises performing the image display using the memory effect without applying the scanning selection signal to the scanning electrode of the display device and without applying the information signal to the information electrode wherein the rewrite of the image is not performed; and means for switching the device between the first, second and third modes, wherein a non-zero voltage of a level which does not cause the image rewrite is applied to the information electrode of the display device during the second mode, and no voltage is applied at the intersection between the scanning electrode and the information electrode of the display device during the third mode, and wherein a mode change between the first and third modes are performed by performing the second mode between the first and third modes.

Claim 32

A driving device of a display device with a memory effect, comprising: means for performing one of first, second and third modes, wherein the first mode comprises successively applying a scanning selection signal to a scanning electrode of the display device and applying an information signal to an information electrode of the display device to perform an image display wherein the image can be rewritten, the second mode comprises performing the image display using the memory effect without applying the scanning selection signal to the scanning electrode of the display device, wherein rewriting of the image is not performed, and the third mode comprises performing the image display using the memory effect without applying the scanning selection signal to the scanning electrode of the display device and without applying the information signal to the information electrode wherein the rewrite of the image is not performed; and means for switching the device between the first, second and third modes, wherein a non-zero voltage of a level which does not cause the image rewrite is applied to the information electrode of the display device during the second mode, and no voltage is applied at the intersection between the scanning electrode and the information electrode of the display device during the third mode, and wherein a mode change between the first and third modes are performed by performing the second mode between the first and third modes.

Claim 33

A device according to claim 23 or 24, wherein said display device includes a smectic liquid crystal.

Claim 34

A device according to claim 23 or 24, wherein said display device includes a ferroelectric liquid crystal.