Lighted dot matrix display

• US 4,289,383 A
• Filed: 09/04/1979
• Issued: 09/15/1981
• Est. Priority Date: 09/04/1979
• Status: Expired due to Term

• Current Assignee: Timex Corporation (Tanager Group BV)
• Original Assignee: Timex Corporation (Tanager Group BV)
• Inventors: Schwarzschild, Jack
• Primary Examiner(s): Bauer, Edward S.
• Application Number:
  US06/071,967
• Time in Patent Office: 742 Days
• Field of Search: 350/334, 350/337, 350/345, 350/332
• US Class Current: 349/19
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G09G 2300/0456 with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2340/14 Solving problems related to the presentation of information to be displayed
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3622 using a passive matrix G09G3/3674 - G09G3/3696 take precedence

Abstract

A dot matrix display of the liquid crystal type operative in either transmissive or reflective modes includes means to illuminate the back of the display, and means for electrically reversing the image on the display from dark on a light background to light (transparent) on dark background for transmissive viewing when the effective light intensity of the illuminating means is greater than the effective ambient light intensity on the front of the display.

Claims

1. In an electrooptic display of the type operable to provide an image viewable either in the transmissive or reflective modes, with means to selectively activate a plurality of electrooptic segments to provide said image, the improvement comprising:

illuminating means disposed to provide light at the back of said display when it functions in a transmissive mode, said illuminating means comprising an incandescent backlight,

image reversal means for electrically reversing the image on said display, and,

a manually actuated switch connected to simultaneously actuate said image reversal means and said illuminating means.

2. The combination according to claim 1, wherein said display is a dot matrix liquid crystal display having groups of row and column segments addressed and multiplexed to provide an image, and wherein said image reversal means comprises a control gate adapted to reverse the polarity of the voltage applied to one of said groups of row or column segments.