Information display device and display control method

• US 6,473,058 B1
• Filed: 03/29/2000
• Issued: 10/29/2002
• Est. Priority Date: 03/31/1999
• Status: Expired due to Term

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Kondo, Takashi, Nanba, Katsuyuki, Tsuji, Sadafusa, Hayami, Isao, Hotomi, Hideo
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): LESPERANCE, JEAN E
• Application Number:
  US09/538,061
• Time in Patent Office: 944 Days
• Field of Search: 345/1.1, 345/1.2, 345/87, 345/173, 345/901, 345/905, 345/211, 345/212, 345/618, 702/63, 340/7.1, 340/7.32, 340/7.37, 340/7.52, 455/572, 455/574, 455/566, 455/556, 455/558, 455/186.1
• US Class Current: 345/1.1
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2300/0486 Cholesteric liquid crystals, including chiral-nematic liquid crystals, with transitions between focal conic, planar, and homeotropic states
• 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 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2358/00 Arrangements for display data security
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: Y10S 345/901 Electronic book with display
• CPC Class Codes: Y10S 345/905 Display device with housing structure

Abstract

An information display device can be structured as an electronic book which has a first screen and a second screen made of liquid crystal with a memory effect. A dry battery can be used as its power source section. The remaining electric power of the battery is detected by measuring the voltage, and immediately before the remaining electric power becomes a minimum voltage necessary for erasure of the screens, the first and second screens are reset so that the images displayed thereon can be erased.

Claims

1. An information display device comprising:

a display section which has a screen made of a material with a memory effect;

a power source section which supplies electric power;

a detecting section which detects a voltage supplied from the power source section;

an erasure mode selecting member with which a user selects an erasure mode to erase at least a portion of the screen; and

a control section which executes the erasure mode on conditions that the erasure mode is selected and that the voltage detected by the detecting section is not more than a specified voltage.

2. An information display device according to claim 1, wherein the control section erases part of the screen in executing the erasure mode.

3. An information display device according to claim 2, wherein the control section erases the screen while skipping pixels at intervals in executing the erasure mode.

4. An information display device according to claim 1, wherein the display section displays an image indicating a detection result of the detecting section.

5. An information display device according to claim 1, wherein the display section has a plurality of screens.

6. An information display device according to claim 5, further comprising a screen selecting member with which a user selects a screen to be erased.

7. An information display device according to claim 5, wherein the control section figures out a number of screens which are capable of being erased in the erasure mode based on a detecting result of the detecting section and determines one or more screens to be erased in the erasure mode in accordance with the number of screens figured out.

8. An information display device according to claim 1, wherein the control section further erases the screen when the power source section is recharged to have a voltage more than the specified voltage.

9. An information display device according to claim 1, wherein the specified voltage is a voltage which is required to erase the screen.

10. A method for controlling a display section, which has a screen made of a material with a memory effect, of an information display device, said method comprising the steps of:

detecting a voltage of a power source section which supplies electric power to the information display device;

selecting an erasure mode to erase the screen; and

executing the erasure mode on conditions that the erasure mode is selected and that the detected voltage is not more than a specified voltage.

11. An information display device comprising:

a display for displaying information using a material with a memory effect which is capable of keeping display information on the display in a state of the display not being supplied with electric power;

a driver for driving the display;

a power source for supplying electric power to the driver;

a detector for detecting the electric power supplied from the power source; and

a controller for controlling the driver to erase the display when the electric power detected by the detector is not more than a specified level.

12. An information display device according to claim 11, wherein said driver sets the display to a focal-conic state to erase the display based on an instruction from the controller.