Display device with power-off delay circuitry

• US 5,952,990 A
• Filed: 02/11/1993
• Issued: 09/14/1999
• Est. Priority Date: 08/18/1986
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inoue, Hiroshi, Mizutome, Atsushi, Netsu, Hiroshi, Kanno, Hideo
• Primary Examiner(s): Mengistu, Amare
• Application Number:
  US08/016,314
• Time in Patent Office: 2,406 Days
• Field of Search: 340/784, 340/811, 340/805, 345/97, 345/85, 345/214, 345/211, 345/212
• US Class Current: 345/97
• CPC Class Codes: G09G 2310/0245 Clearing or presetting the whole screen independently of waveforms, e.g. on power-on G09G2310/063 takes precedence
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3674 Details of drivers for scan electrodes

Abstract

A driving and switching off circuit is provided for a liquid crystal display device having a memory effect and a plurality of pixels, with each pixel capable of exhibiting two states in accordance with an electric field applied thereto. The circuit comprises a driving circuit for applying a drive signal to the display device to cause all of the pixels to uniformly exhibit one of the two states, a delay circuit for providing an end signal subsequent to the application of the drive signal and a switching circuit, responsive to the delay circuit, for switching off the display device subsequent to causing all the pixels to uniformly exhibit the one state.

Claims

1. A driving and switching off circuit for a liquid crystal display device having a memory effect and a plurality of pixels, each pixel having the capability of exhibiting two states in accordance with an electric field applied thereto, said circuit comprising:

driving means for applying a drive signal to said display device to cause all of said pixels to uniformly exhibit one of said two states;

delay means for providing an end signal subsequent to the application of said drive signal; and

means responsive to said delay means for switching off said display device subsequent to causing all the pixels to uniformly exhibit said one state.

2. A method for driving and switching off a liquid crystal display device having a memory effect and a plurality of pixels, each pixel having the capability of exhibiting two states in accordance with an electric field applied thereto, said method comprising the steps of:

generating a turn off signal to turn off said display device;

applying a drive signal, in response to said turn off signal, to said display device to cause all of said pixels to uniformly exhibit one of said two states;

providing an end signal subsequent to the application of said drive signal;

thereafter, in response to the end signal, switching off said display device subsequent to causing all the pixels to uniformly exhibit said one state.

3. A driving and switching off circuit for a liquid crystal display device having a memory effect and a plurality of pixels, each pixel having the capability of exhibiting two states in accordance with an electric field applied thereto, said circuit comprising:

driving means for applying a drive signal to said display device to cause all of said pixels to uniformly exhibit one of said two states;

delay means for providing a delay signal ending subsequent to the application of said drive signal; and

means responsive to said delay means for switching off said display device subsequent to causing all the pixels to uniformly exhibit said one state.

4. A method for driving and switching off a liquid crystal display device having a memory effect and a plurality of pixels, each pixel having the capability of exhibiting two states in accordance with an electric field applied thereto, said method comprising the steps of:

generating a turn off signal to turn off said display device;

applying a drive signal, in response to said turn off signal, to said display device to cause all of said pixels to uniformly exhibit one of said two states;

delaying said turn off signal to provide a delayed turn off signal ending subsequent to the application of said drive signal; and

thereafter, in response to the delayed turn off signal, switching off said display device.