Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-01-19
2001-01-16
Hjerpe, Richard A. (Department: 2774)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
Reexamination Certificate
active
06175353
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to display apparatus generally and, in particular, to such apparatus having an illuminated background against which displayed alphanumeric characters, and graphics symbols are viewed.
BACKGROUND OF THE INVENTION
A plentitude of battery powered, hand-held solid state devices are provided with display screens adapted for specialized applications. Examples of such devices include, computers, distance measuring devices, navigational instruments, paging devices, and communications devices generally, including telephone handsets adapted to receive e-mail. This list is not exhaustive, but serves to illustrate the utilitarian nature of alphanumeric, and graphics display screens which are essential where an alphanumeric data or graphics readout is required.
Under conditions of sufficient ambient light level, these screens perform adequately. At low level light conditions, however, illumination is required to read the data carried by the screen. Where an external power source provides operating current for the device, screen illumination is not generally a problem. However where the device relies on a self-contained source of battery power, illumination becomes problematic since the current requirements of illumination components generally impose a substantial current drain from the battery. Light emitting diodes (LEDs) are particularly notorious in this regard. Power conservation in battery powered devices of the type described is therefore a major concern for equipment designers and users alike.
SUMMARY OF THE INVENTION
Having regard to the aforedescribed problem associated with battery power conservation, a principal provision of the present invention is display apparatus having a controllable illumination screen against which opaque symbols formed on a transparent reflective viewing screen can be viewed.
Another provision of the invention is display apparatus in which the illumination screen is adapted to be energized selectively so that only discrete portions provide illumination for viewing corresponding portions of the viewing screen, and its opaque symbols.
The above-mentioned provisions effectively create a selective energization for controlling the illumination means against which the symbols on the substrate can be viewed. For clarity of terminology, the portion of the illumination means being under selective energization control will be referenced herein as a controllably variable area.
Yet another provision of the invention is display apparatus having a positionable cover for covering portions of the screen that are not viewed, and circuit means responsive to the cover position that restorably inhibit illumination of a covered screen portion.
A still further provision of the invention is display apparatus that embodies sensing devices to extinguish any and all illuminated regions of the illumination screen in the absence of data on the viewing screen, when ambient light levels are high, or when the apparatus is placed within a predetermined distance to a user, notably when a telephone handset is moved from a read position to a talk and listen position alongside a user's face.
The problems associated with the prior art may be substantially overcome, and the foregoing provisions achieved by recourse to one aspect of the invention which relates to display apparatus that comprises, in combination, a transparent viewing screen having a reflective substrate adapted to form transitory opaque symbols thereon in response to respective ones of input data signals, means for applying the data signals to selected portions of the substrate, illumination means disposed in registry with the screen for backlighting the substrate in response to respective ones of input control signals, and control means coupled with the illumination means for applying the control signals thereto to illuminate the controllably variable area, of the illumination means against which the symbols on the substrate can be viewed.
Another aspect of the invention is a method for viewing a transparent screen having a reflective substrate adapted to form transitory opaque symbols thereon in response to respective ones of input data signals, and illumination means positioned in registry with the screen for backlighting a predetermined portion of the substrate in response to respective ones of control signals input to the illumination means, the method comprising the steps of generating the control signals in coincidence with the data signals, applying the data signals to selected portions of the substrate, and applying the control signals to the illumination means concurrently with the data signals at the substrate for illuminating the controllably variable area of illumination of the illumination means against which corresponding ones of the symbols on the substrate can be viewed.
A further aspect of the invention is a method for viewing a transparent screen having a reflective substrate adapted to form transitory opaque symbols thereon in response to respective ones of input data signals, and segmented illumination means positioned in registry with the screen for backlighting a predetermined portion of the substrate in response to respective ones of control signals input to the illumination means, the method comprising the steps of generating the control signals, applying the data signals to selected portions of the substrate, and applying the control signals to the illumination means for illuminating a predetermined segment thereof comprising the controllably variable area of illumination against which the symbols on the substrate can be viewed.
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Haszko Dennis R.
Hjerpe Richard A.
Laneau Ronald
Nortel Networks Limited
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