Systems and methods for multi-state switch networks

• US 8,686,658 B2
• Filed: 04/17/2013
• Issued: 04/01/2014
• Est. Priority Date: 01/05/2007
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Terlizzi, Jeffrey, Kalayjian, Nicholas R.
• Primary Examiner(s): VU, JIMMY T
• Application Number:
  US13/864,925
• Publication Number:
  US 20130234610A1
• Time in Patent Office: 349 Days
• Field of Search: 315/185.R, 315/209.R, 315/225, 315/291, 315/307, 315/308, 315/312
• US Class Current: 315/209.R
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A multi-state switch network is provided that includes a serially connected diode pair configured to receive a single control signal at a control node. The serially-connected diode pair is configured to control a pair of switches. Moreover, the single control signal is operative to drive the serially connected diode pair to a first state, a second state, or a third state based at least in part on a state of the single control signal. Furthermore, the single control signal is operative to alternatively turn ON a first diode of the diode pair and turn OFF a second diode of the diode pair when the state of the single control signal is a first state, turn OFF the first diode and turn ON the second diode when the state of the single control signal is a second state, and turn OFF the first diode and turn OFF the second diode when the state of the single control signal is a third state.

Claims

1. A multi-state switch network comprising:

a serially connected diode pair configured to receive a single control signal at a control node, wherein the serially-connected diode pair is configured to control a pair of switches;

wherein the single control signal is operative to drive the serially connected diode pair to a first state, a second state, or a third state based at least in part on a state of the single control signal; and

wherein the single control signal is operative to alternatively;

turn ON a first diode of the diode pair and turn OFF a second diode of the diode pair when the state of the single control signal is a first state;

turn OFF the first diode and turn ON the second diode when the state of the single control signal is a second state; and

turn OFF the first diode and turn OFF the second diode when the state of the single control signal is a third state.

2. The multi-state switch network of claim 1, wherein the serially-connected diode pair comprises a pair of light emitting diodes (LEDs).

3. The multi-state switch network of claim 2, comprising a pulse-width modulator that modulates the single control signal to control a perceived brightness level of the pair of LEDs.

4. The multi-state switch network of claim 3, wherein the pulse-width modulator is operative to adjust a duty cycle of the single control signal based on a monitored voltage level.

5. The multi-state switch network of claim 4, wherein the pulse-width modulator is operative to decrease the duty cycle of the single control signal based on an increase in the monitored voltage level.

6. The multi-state switch network of claim 1, wherein:

the first state comprises a higher voltage state; and

the second state comprises a lower voltage state.

7. The multi-state switch network of claim 1, wherein the serially-connected diode pair consists essentially of two diodes and two resistors in serial communication.

8. The multi-state switch network of claim 1, comprising a tri-state buffer that provides the control signal.

9. A multi-state switch network comprising:

a serially connected diode pair configured to receive a single control signal at a control node; and

a control node, wherein;

a first diode of the diode pair is serially coupled between a power source and the control node;

a second diode of the diode pair is serially coupled between the control node and a ground source;

a first switch serially coupled between the first diode and the control node;

a second switch serially coupled between the second diode and the control node,

wherein the single control signal is operative to drive the serially connected diode pair to a first state, a second state, or a third state based at least in part on a state of the single control signal;

wherein the single control signal is operative to alternatively;

turn ON the first diode of the diode pair and switch the first switch and turn OFF the second diode of the diode pair when the state of the single control signal is a first state;

turn OFF the first diode and turn ON the second diode and switch the second switch when the state of the single control signal is a second state; and

turn OFF the first diode and turn OFF the second diode when the state of the single control signal is a third state.

10. The multi-state switch network of claim 9, comprising:

a first resistor; and

a second resistor, wherein;

the first resistor is serially coupled between the first diode and the control node; and

the second resistor is serially coupled between the second diode and the control node.

11. The multi-state switch network of claim 9, wherein the first switch comprises one of a transistor switch, a buffer, and a logic circuit.

12. The multi-state switch network of claim 9, wherein the second switch comprises one of a transistor switch, a buffer, and a logic circuit.

13. The multi-state switch network of claim 9, comprising a pulse-width modulator configured to increase a duty cycle of the single control signal based on a decrease in a monitored voltage level.

14. The multi-state switch network of claim 9, wherein the first and second diode each comprise a light emitting diode.

15. A method of controlling a multi-state switch network comprising first and second diodes, the method comprising:

receiving a single control signal at a control node;

in response to the single control signal, alternatively;

turning ON the first diode and turning OFF the second diode when the single control signal is in a first state;

turning OFF the first diode and turning ON the second diode when the single control signal is in a second state;

turning OFF the first diode and turning OFF the second diode when the single control signal is in a third state;

switching a first switch of the pair of switches in response to turning ON the first diode; and

switching a second switch of the pair of switches in response to turning ON the second diode.

16. The method of claim 15, wherein the first diode and the second diode are LEDs.

17. The method of claim 16, comprising pulse-width modulating the single control signal to control a perceived brightness level of the LEDs.

18. The method of claim 16, comprising:

monitoring a voltage level of a power source; and

adjusting a duty cycle of the control signal based on the monitored voltage level.

19. The method of claim 15, wherein the first state comprises a high voltage state.

20. The method of claim 15, wherein the second state comprises a low voltage state.