Electro-optical device and process for fabricating the same and method of driving the same

Claim 1

An electro-optical device of an active matrix type comprising: a pixel comprising a first element for selecting said pixel, a memory element for storing an output of said first element where said memory element comprises a ferroelectric capacitor comprising a pair of electrodes and ferroelectric material provided between said electrodes, and a second element for feeding electric power to said pixel based on the stored output such that the second element is turned on when the stored output exceeds a predetermined voltage so that the electric power can be fed to said pixel and whereby the spontaneous polarization of the ferroelectric capacitor defines a lower limit for said stored output while said electric power is being fed to said pixel and whereby the ferroelectric capacitor, in response to storing a further output of said first element, is reversed in polarity to turn the second element off so that the electric power can not be fed to the pixel.

Claim 12

The method of driving an electro-optical device comprising the steps of: rewriting pixels by applying a pulse to a gate electrode of a first transistor connected with one electrode of a nonvolatile capacitor at one of source and drain of said first transistor only after changing a polarity of an alternating electric potential and while applying said alternating electric potential to the other one of said source and drain, and applying a zero voltage to one of source and drain of a second transistor before the application of said pulse, the other one of said source and drain of said second transistor being connected with a pixel electrode, and a gate electrode of said second transistor being connected with the other electrode of said nonvolatile capacitor.

Claim 13

The method of driving an electro-optical device comprising the steps of: rewriting pixels by applying a pulse to a gate electrode of a first transistor connected with one electrode of a nonvolatile capacitor at one of source and drain of said first transistor only after changing a polarity of an alternating electric potential and while applying said alternating electric potential to the other one of said source and drain, and applying a zero voltage to one of source and drain of a second transistor before the application of said pulse, the other one of said source and drain of said second transistor being connected with a pixel electrode, and a gate electrode of said second transistor being connected with the other electrode of said nonvolatile capacitor.

Claim 16

A method of driving an electro-optical device of an active matrix type, having a plurality of pixels, each of said pixels being provided with a first switching element for selecting a corresponding pixel in response to a select signal supplied thereto, a nonvolatile memory element comprising a ferroelectric capacitor for storing an output of said first switching element, and a second switching element for switching the corresponding pixel in response to the output of said first switching element stored by said memory element such that the second switching element is turned on when the stored output exceeds a predetermined voltage so that electric power can be fed to said pixel and whereby the spontaneous polarization of the ferroelectric capacitor defines a lower limit for said stored output while said electric power is being fed to said pixel and whereby the ferroelectric capacitor, in response to storing a further output of said first switching element, is reversed in polarity to turn the second element off so that the electric power can not be fed to the pixel, said method comprising the steps of: addressing the first switching element of one of said pixels to be rewritten with a select signal in order that said first switching element outputs either ON or OFF signal; supplying a voltage to said one of the pixels through the corresponding second switching element continuously when the corresponding memory element stores said ON signal, and stopping supplying the voltage to said one of the pixels when the corresponding memory element stores said OFF signal.

Claim 17

A method of driving an electro-optical device of an active matrix type, having a plurality of pixels, each of said pixels being provided with a first switching element for selecting a corresponding pixel in response to a select signal supplied thereto, a nonvolatile memory element comprising a ferroelectric capacitor for storing an output of said first switching element, and a second switching element for switching the corresponding pixel in response to the output of said first switching element stored by said memory element such that the second switching element is turned on when the stored output exceeds a predetermined voltage so that electric power can be fed to said pixel and whereby the spontaneous polarization of the ferroelectric capacitor defines a lower limit for said stored output while said electric power is being fed to said pixel and whereby the ferroelectric capacitor, in response to storing a further output of said first switching element, is reversed in polarity to turn the second element off so that the electric power can not be fed to the pixel, said method comprising the steps of: addressing the first switching element of one of said pixels to be rewritten with a select signal in order that said first switching element outputs either ON or OFF signal; supplying a voltage to said one of the pixels through the corresponding second switching element continuously when the corresponding memory element stores said ON signal, and stopping supplying the voltage to said one of the pixels when the corresponding memory element stores said OFF signal.

Claim 24

A method of driving an electro-optical device of an active matrix type wherein said electro-optical device comprises an addressing line, a data line, a voltage supplying line, a first transistor, a second transistor, and a non-volatile capacitor connected between said first transistor and said second transistor, and said addressing line is connected with a gate electrode of said first transistor and said data line is connected with a drain of said first transistor and said voltage supplying line is connected with a drain of said second transistor, and wherein said nonvolatile capacitor comprises a pair of electrodes and a ferroelectrics provided between said electrodes, and one of said electrodes is connected with a source of said first transistor and the other one of said electrodes is connected with a gate electrode of said second transistor, said method comprising the step of: addressing pixels at an addressing period longer than a period of alternating potential of a pixel electrode of said electro-optical device.

Claim 25

A method of driving an electro-optical device of an active matrix type wherein said electro-optical device comprises an addressing line, a data line, a voltage supplying line, a first transistor, a second transistor, and a non-volatile capacitor connected between said first transistor and said second transistor, and said addressing line is connected with a gate electrode of said first transistor and said data line is connected with a drain of said first transistor and said voltage supplying line is connected with a drain of said second transistor, and wherein said nonvolatile capacitor comprises a pair of electrodes and a ferroelectrics provided between said electrodes, and one of said electrodes is connected with a source of said first transistor and the other one of said electrodes is connected with a gate electrode of said second transistor, said method comprising the step of: addressing pixels at an addressing period longer than a period of alternating potential of a pixel electrode of said electro-optical device.