Systems and methods for driving a display device and interrupting a feedback
In a driver for a luminescent display the operating voltage of a driver circuit is monitored to prevent extra dissipation due to open output connections ( 28 ) of the driver circuit. The monitoring is also used for minimizing power dissipation.
1. A display device comprising:
a number of picture elements; and
a display driver device, comprising:
driving transistors to be connected in series with the picture elements;
means for monitoring output voltages at output nodes of the display driver device;
a feedback mechanism configured to operate in response to the output voltages to control a reference voltage of the display driver device and to maintain substantially constant a voltage value between a supply node and the output nodes;
means for detecting one or more open outputs at one or more of the output nodes of the display driver device; and
means for inhibiting the feedback mechanism from responding to the output voltages at the one or more output nodes having the open outputs upon detection by the detecting means of the one or more open outputs.
2. The display device as claimed in claim 1 , further comprising means for signaling when an output voltage reaches a threshold voltage.
3. The display device as claimed in claim 1 , wherein the feedback mechanism further comprises a control circuit for signaling a difference between an output voltage of the display driver device for a picture element and the reference voltage being below a threshold voltage.
4. The display device as claimed in claim 3 , wherein the means for detecting the open output are configured to perform the detecting after the signaling.
5. The display device as claimed in claim 3 , wherein the means for detecting includes a differential amplifier.
6. The display device as claimed in claim 1 , wherein the display driver device comprises current sources each including one of the transistors, and the feedback mechanism is configured for keeping substantially constant a difference between an output voltage of the display driver device for a picture element and the reference voltage.
7. The display device as claimed in claim 1 , wherein the picture elements include a luminescent element having a luminescence determined by first current.
8. The display device of claim 1 , wherein the means for inhibiting includes a plurality of switches connected between the supply node and the output nodes, wherein one or more of the switches are opened upon detection of the one or more open outputs.
9. A display driver device comprising:
driving transistors to be connected in series with picture elements;
means for monitoring output voltages at output nodes of the display driver device;
a feedback mechanism configured to operate in response to the output voltages to control a reference voltage of the display driver device and to maintain substantially constant a voltage value between a supply node and the output nodes; and
a detector including a differential amplifier for detecting one or more open outputs at one or more of the output nodes of the display driver device and inhibiting the feedback mechanism from responding to the outpost voltages at the one or more output nodes having upon detection by the detecting means of the one or more open outputs.
10. The display driver device as claimed in claim 9 , further comprising means for signaling when an output voltage reaches a threshold voltage.
11. The display driver as claimed in claim 9 , wherein the feedback mechanism further comprises a control circuit for signaling a difference between an output voltage of the display driver device for a picture element and the reference voltage being below a threshold voltage.
12. The display driver device of claim 9 , wherein the detector includes a plurality of switches connected between the supply node and the output nodes, wherein one or more of the switches are opened upon detection of the one or more open outputs.
13. A display driver, comprising:
a plurality of current sources for supplying current to pixels of a display device, each current source being connected to an output node of the display driver; means for monitoring output voltages at the output nodes; a feedback mechanism configured to operate in response to the output voltages to control a reference voltage of the display driver and to maintain substantially constant a voltage value between a supply node and the output nodes; and
means for inhibiting the feedback mechanism from responding to the output voltages at one or more output nodes which have open outputs.
means for detecting one or more open outputs at one or more of the output nodes, and wherein the means for inhibiting includes a plurality of switches connected between the supply node and the output nodes, wherein one or more of the switches are opened upon detection of the one or more open outputs.
14. The display driver of claim 13 , wherein the means for inhibiting comprises a plurality of fuses.