DIGITAL DRIVING CIRCUITS, METHODS AND SYSTEMS FOR LIQUID CRYSTAL DISPLAY DEVICES

• US 20110169814A1
• Filed: 01/14/2011
• Published: 07/14/2011
• Est. Priority Date: 01/14/2010
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Van Ess, David, Keeser, Christopher C., Murphy, Robert L., Wright, David G.
• Granted Patent: US 8,773,420 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 3/04 for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions
• CPC Class Codes: G09G 3/18 using liquid crystals
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A method may include controlling a display device in at least first mode by varying a correlation between display driver signals applied across display segments within the display device; wherein the display driver signals vary between substantially only two levels, and a display segment is activated when an average voltage magnitude across the segment over a time period exceeds a threshold value.

Claims

1. A method, comprising:

controlling a display device in at least first mode by varying a correlation between display driver signals applied across display segments within the display device;

wherein

the display driver signals vary between substantially only two levels, and a display segment is activated when an average voltage magnitude across the segment over a time period exceeds a threshold value.

2. The method of claim 1, wherein:

varying the correlation between display driver signals includes

generating a plurality of common driver signals that each includes frames of N timeslots, including one selection time slot and N−

1 de-selection timeslots, the selection timeslot being different for each common driver signal.

3. The method of claim 2, further including:

varying the correlation between display driver signals includes

generating at least one segment driver signal having frames of N timeslots corresponding to the common driver signals;

wherein

the segment is activated when the average voltage magnitude between corresponding common and segment driver signals exceeds a voltage threshold in a timeslot.

4. The method of claim 2, further including:

each common driver signal repeats every frame; and

generating at least one segment driver signal having frames of N timeslots corresponding to the common driver signal, the segment driver signal varying a correlation to at least one common driver signals in response to display data.

5. The method of claim 1, further including:

controlling a display device in at least a second mode by

varying a pulse density of display driver signals applied to the electrodes of display segments within the display device; and

filtering the display driver signals to provide voltage levels across display segments that vary according to pulse density

6. The method of claim 5, further including:

filtering the display driver signals includes filtering with a frequency filter that includes at least a portion of a liquid crystal display device.

7. The method of claim 1, further including:

switching between at least the first mode and a second mode in response to a mode indication.

8. The method of claim 7, wherein:

the first mode is a low power mode and the second mode is a higher power mode.

9. A method, comprising:

generating a plurality of time division multiplexed common driver signals and segment driver signals that vary substantially between only two levels;

in a first mode, activating display segments by varying a correlation between common and segment driver signals connected to such display segments; and

in a second mode, activating display segments by at least varying voltage levels of a common driver signal as received by the display segments.

10. The method of claim 9, wherein:

in the first mode

generating common driver signals that vary according to a predetermined sequence; and

generating segment driver signals that selectively correlates with at least one common driver signal in response to display data to exceed a minimum average voltage over a time period;

wherein

a display segment is activated or not activated depending upon whether a voltage exceeds exceed the minimum average voltage over the time period.

11. The method of claim 10, wherein:

the common and segment driver signals include frames, each having a plurality of timeslots, and the time period comprises one of the time slots.

12. The method of claim 9, further including:

in the second mode

generating common driver signals having a variable pulse density, and

filtering the variable pulse density signals to generate the varying voltage levels received by the display segments.

13. The method of claim 12, wherein:

filtering the variable pulse density signals includes forming a frequency filter that includes at least a portion of a liquid crystal display.

14. The method of claim 9, further including:

further varying a pulse density of at least the common driver signals or the segment driver signals in response to an intensity value.

15. A system, comprising:

a first signal generator circuit that generates control signals that vary between substantially only two levels, and have predetermined correlations with respect to one another; and

a selection driver circuit having at least a first mode that selectively couples selected controls signals to common display connection points, and couples selected control signals to segment connection points in response to at least display data;

wherein

a display segment connected between a common and segment connection point with signals above the minimum correlation will be activated.

16. The system of claim 15, wherein:

the selection driver circuit includes

a common section that time division multiplexes control signals to a plurality of common connection points in a predetermined sequence, and

a segment section that time division multiplexes control signals to a plurality of common connection points in response to at least display data.

17. The system of claim 15, further including:

a second signal generator circuit that generates a plurality of intensity signals that substantially do not correlate with the control signals; and

an intensity varying circuit that logically combines the intensity signals with signals output from the selection driver circuit.

18. The system of claim 15, further including:

the selection driver circuit has at least a second mode that generates at least one control signal having a predetermined frequency; and

a display structure coupled to the common and segment connection points having an inherent capacitance that forms at least a portion of a frequency filter, the predetermined frequency being outside a passband of the frequency filter.

19. The system of claim 15, wherein:

the first signal generator circuit, first selection circuit and second selection circuit comprise programmable digital logic blocks configured with configuration data.

20. The system of claim 15, wherein:

a liquid crystal display coupled to the common and segment connection points.