Automatic activity detection in a display controller

• US 8,766,956 B2
• Filed: 12/08/2008
• Issued: 07/01/2014
• Est. Priority Date: 10/18/2004
• Status: Active Grant

• Current Assignee: Tamiras Per Pte Ltd LLC (Intellectual Ventures LLC)
• Original Assignee: Tamiras Per Pte Ltd LLC (Intellectual Ventures LLC)
• Inventors: Noorbakhsh, Ali, Keene, David, Lattanzi, John, Chilukuri, Ram
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): Shapiro, Leonid
• Application Number:
  US12/330,420
• Publication Number:
  US 20090146979A1
• Time in Patent Office: 2,031 Days
• Field of Search: 345/204, 345/690, 345/55
• US Class Current: 345/204
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 3/2096 Details of the interface to the display terminal specific for a flat panel suitable for both CRT and flat panel G09G5/006; specific for a CRT G09G1/167
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04

Abstract

Detecting when the on-board power supply is powered on or off by an auto activity detection circuit by determining if the reference clock signal (T_CLK) is toggling and if the reference clock signal is toggling, then charging a capacitor to a high voltage in the auto activity detection circuit based on the toggling reference clock signal, and outputting an on-board power supply activity signal based upon the high voltage by the auto activity detection circuit indicative of whether or not the on-board power supply is active.

Claims

1. An auto activity detection circuit configured to determine whether an on-board power supply is on, the auto activity detection circuit comprising:

an input node configured to receive a clock signal;

an output node coupled to a node N1;

a resistor having a resistor first terminal connected to the input node and a resistor second terminal connected to the node N1; and

an RC circuit section connected to the resistor second terminal at the node N1, wherein in response to the clock signal toggling, the RC circuit section is configured to drive the output node to a state indicating that the on-board power supply is on.

2. The auto activity detection circuit as recited in claim 1, wherein, in response to the clock signal toggling, the RC circuit section is configured to charge the node N1 to a predetermined voltage and thereby drive the output node to the state indicating that the on-board power supply is powered on.

3. The auto activity detection circuit as recited in claim 2, wherein the state is a binary HIGH.

4. The auto activity detection circuit as recited in claim 3, further comprising:

a first inverter having a first inverter input coupled to the node N1 and a first inverter output; and

a second inverter having a second inverter input coupled in series with the first inverter output and a second inverter output coupled to a node N2.

5. The auto activity detection circuit as recited in claim 4, further comprising:

a first logic circuit having a first input coupled to the node N2 and a second input coupled to a signal detector, and an output;

a third inverter having a third inverter input coupled to the output of the first logic circuit and having a third inverter output coupled to a node N3;

a second logic circuit having a first input coupled to the node N3, a second input coupled to an enable signal generator, and an output; and

a fourth inverter having a fourth inverter input coupled to the output of the second logic circuit and an output coupled to the output node, wherein in response to the node N1 reaching the predetermined voltage representing the binary HIGH, the node N2, in turn, has a voltage representing a binary HIGH, and if the signal detector detects a signal, then the node N3 has a voltage representing a binary HIGH resulting in an output signal at the output node having a voltage representing a binary HIGH indicating that the on-board power supply is on.

6. The auto activity detection circuit as recited in claim 5, wherein the enable signal generator is configured to generate an enable signal configured to cause the output signal to have a voltage representing a binary HIGH indicating that the on-board power supply is on.

7. The auto activity detection circuit as recited in claim 5, wherein the first logic circuit is a NAND gate and the second logic circuit is a NOR gate.

8. An auto activity detection circuit configured to determine whether an on-board power supply is on, the auto activity detection circuit comprising:

an input node configured to receive a clock signal;

an output node coupled to a node N1;

a resistor having a resistor first terminal connected to the input node and a resistor second terminal connected to the node N1;

an RC circuit section connected to the resistor second terminal at the node N1, wherein in response to the clock signal toggling at a frequency, the RC circuit section is configured to drive the node N1 to a voltage indicating that the on-board power supply is on; and

a first logic circuit having a first input coupled to the node N1 and a second input coupled to a signal detector, wherein in response to the first input receiving the voltage at the node N1 indicating that the on-board power supply is on and the second input receiving a signal from the signal detector indicating that the on-board power supply is on, the first logic circuit outputs an output signal to the output node indicating that the on-board power supply is on.

9. The auto activity detection circuit as recited in claim 8, further comprising a second logic circuit having a first input coupled to the output of the first logic circuit, a second input coupled to an enable signal generator, and an output coupled to the output node.

10. The auto activity detection circuit as recited in claim 9, wherein the voltage indicating that the on-board power supply is on is a binary HIGH, and wherein the enable signal generator is configured to generate an enable signal that causes the second logic circuit to output to the output node a binary HIGH indicating that the on-board power supply is on.

11. An auto activity detection circuit configured to determine whether an on-board power supply is on, the auto activity detection circuit comprising:

an input node configured to receive a clock signal;

a resistor having a resistor first terminal connected to the input node and a resistor second terminal connected to a node N1;

an RC circuit section connected to the resistor second terminal at the node N1, wherein in response to receipt of a clock signal toggling at a frequency, the RC circuit section is configured to drive the node N1 to a predetermined voltage indicating that the on-board power supply is on; and

a first logic circuit having a first input coupled to the node N1 and a second input coupled to receive a signal that is in a binary HIGH state when the on-board power supply is on, wherein in response to the node N1 being at the predetermined voltage and the signal being received in a binary HIGH state, the first logic circuit outputs an output signal to the output node indicating that the on-board power supply is on.

12. The auto activity detection circuit as recited in claim 11, further comprising a second logic circuit that is coupled between the first logic circuit and the output node, wherein a first input of the second logic circuit is configured to receive the output signal from the first logic circuit, and wherein a second input of the second logic circuit is configured to receive a signal from an enable signal generator configured to cause the second logic circuit to output the output signal to the output node indicating that the on-board power supply is powered on.