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AssigneeCypress Semiconductor Corporation
InventorsDavid Van Ess, Christopher Corson Keeser, Robert LeRoy Murphy, David G. Wright
Estimating the term…
A method may include generating display driver signals that vary between only two levels and applying the display driver signals to opposing electrodes of a display segment within a display device. An intrinsic capacitance of the display device filters the display driver signals to generate different analog signal levels at the display segment of the display device. The method varies the pulse density of the display driver signals to select or de-select the display segment based on an average voltage magnitude across the display segment over a time period. The display segment is activated when the average voltage magnitude exceeds a threshold value.
A method comprising:
A method comprising:
A system comprising:
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Using liquid crystals: control of matrices with row and column drivers
Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes: for presentation of a single…
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About 5 years 1 month of term left · ends 15 Nov 2031 (estimated)
The present disclosure relates generally to display control devices, and more particularly to display control devices that enable/disable display segments according to a voltage applied across such segments.
Display technologies, such as liquid crystal display (LCDs), can activate segments of a display according to signals applied across the segments. Conventionally, technology for driving LCDs directly requires dedicated hardware to generate and sequence specific analog voltage levels in order to properly drive a display. Waveforms are generated using such multiple signal levels to either turn on or off each segment. Typically, such multiple signal levels include a high bias voltage, and multiple other intermediate voltage levels proportional to the high bias voltage. A high bias voltage is typically an analog value that may be varied to increase or decrease a contrast of display segments. The generation of a variable high bias voltage and multiple intermediate voltages can be costly in terms of integrated circuit die area, and in some cases power.
A typical LCD display may include multiple “commons”. Each common may be connected to a corresponding set of LCD segments. Commons may be driven to an analog selection voltage in a time division multiplexed fashion such that only one commons is driven to an analog selection voltage at a time. When not driven to a selection voltage, each common may be driven to one of many different analog de-selection voltage levels.
FIG. 1 is a block schematic diagram of a display control system according to one embodiment.
FIG. 2 is a block schematic diagram of a display control system that applies digital signals to a frequency filter, which may be formed with a display device, according to one embodiment.
FIG. 3 is a side cross sectional view showing a portion of a liquid crystal display (LCD) that may be included in embodiments.
Various embodiments will now be described that show circuits, systems and methods that can control a segmented display, such as a liquid crystal display (LCD), with digital (e.g., binary level) signals, and thus avoid analog circuits like those included in conventional approaches.
Some may generate display driver signals that vary between only two levels and are applied to opposing electrodes of a display segment. Correlation of such opposing driver signals may be used to select or de-select the segment based on an average voltage magnitude across the segment over a time period (e.g., root mean square).
Other embodiments may provide one or more driving methods in addition to the signal correlation method noted above, and enable switching between such different operating modes. One such alternate mode may include generating display driver signals that vary between only two levels, but may change in pulse density. An inherent features (e.g., capacitance and/or resistance) of a display (e.g., LCD display) may be utilized as all or part of a filter to cause the varying pulse densities to generate different voltage levels at segments of the display.