Gamma reference voltage generator
View Patent ↗A programmable buffer integrated circuit which can be programmed to output a set of gamma correction reference voltages to be used in LCD displays. Once programmed, the buffers will continuously output the programmed value. The device incorporates a programming interface to allow the programming of the buffer outputs to the desired values during manufacturing and test of the panel. Multiple sets of values can be programmed to provide different gamma correction curves for different user or application requirements.
1. An integrated circuit for producing voltage signals on a plurality of outputs comprising:
a plurality of non-volatile storage cells;
circuits for programming coupled to a multiplexer for addressing and programming said storage cells, wherein the addressing is based on a plurality of inputs;
drivers connected to said storage cells and to the plurality of outputs; and
the plurality of inputs connected to said multiplexer for addressing said storage cells,
wherein said voltage signals are gamma reference voltage signals for determining actual driving voltages of columns of a display, wherein said non-volatile storage cells are organized into two or more banks of cells wherein each bank contains a predetermined gamma reference voltage signal display condition; and means to switch between the banks based on one or more external signals is provided on said integrated circuit.
2. The integrated circuit of claim 1 wherein said non-volatile storage cells are reprogrammable.
3. The integrated circuit of claim 2 wherein said means to switch between banks can have a switching time from about 10 msec to about one second.
4. The integrated circuit of claim 1 wherein said non-volatile storage cells hold analog voltage values which are a constant fraction of said gamma reference voltage signals.
5. The integrated circuit of claim 1 wherein said circuits for programming require an external source for the high voltage programming means.
6. A method of programming a gamma reference voltage generator integrated circuit comprising the steps:
a. selecting a predetermined address using all address lines;
b. taking a programming pin high;
c. selecting a predetermined group of storage addresses using a predetermined subset of the address lines;
d. taking the programming pin high to latch the predetermined group of storage address;
e. selecting a predetermined storage cell address using all of the address lines;
f. programming an applied gamma voltage in the selected storage cell by applying incremental voltage pulses from the programming pin;
g. monitoring the result of said incremental voltage pulses by reading an output buffer line associated with said selected storage cell; and
h. continuing the incremental voltage pulses from the programming pin until the output buffer line associated with said selected storage cell achieves a predetermined value.
7. The method of claim 6 wherein said gamma reference voltage generator integrated circuit requires an external source for supplying high voltage to the programming pin.
8. An integrated circuit for producing voltage signals on a plurality of outputs comprising:
a plurality of non-volatile storage cells;
circuits for programming coupled to a multiplexer for addressing and programming said storage cells, wherein the addressing is based on a plurality of inputs;
drivers connected to said storage cells and to the plurality of outputs;
the plurality of inputs connected to said multiplexer for addressing said storage cells; and
an output pin connected to an output through a second multiplexer connected to said plurality of outputs wherein said output pin is at an output buffer voltage level of said output when said integrated circuit is in a programming mode to program said storage for said output.
9. The integrated circuit of claim 8 wherein said non-volatile storage cells are reprogrammable.
10. The integrated circuit of claim 9 wherein said reprogrammable, non-volatile storage cells are organized into two or more banks of cells wherein each bank contains a predetermined gamma reference voltage signal display condition; and means to switch between the banks based on one or more external signals is provided on said integrated circuit.
11. The integrated circuit of claim 10 wherein said means to switch between banks can have a switching time from about 10 msec to about one second.
12. The integrated circuit of claim 8 wherein said voltage signals are gamma reference voltage signals for driving columns of a display.
13. The integrated circuit of claim 8 wherein said non-volatile storage cells hold analog voltage values which are a constant fraction of said gamma reference voltage signals.
14. The integrated circuit of claim 8 wherein said circuits for programming require an external source for supplying high voltage.