LED driver circuitry for an infrared scene projector system
A circuit for driving a light emitting diode (LED) comprises a plurality of current supply level circuits wherein each current supply level circuit is configured to control a different amount of electric current flowing through the LED. Each current supply level circuit includes a circuit enable transistor, a drive current transistor, and a gain control transistor. The circuit enable transistor is configured to enable current flow through the current supply level circuit. The drive current transistor is configured to control an amount of electric current flowing through the current supply level circuit. The gain control transistor is configured to control a range of the amount of electric current flowing through the current supply level circuit.
1. A circuit for driving a light emitting diode (LED), the circuit comprising:
a plurality of current supply level circuits, each current supply level circuit configured to control a different amount of electric current flowing through the LED, each current supply level circuit including:
a circuit enable transistor configured to enable current flow through the current supply level circuit,
a drive current transistor configured to control an amount of electric current flowing through the current supply level circuit, and
a gain control transistor configured to control a range of the amount of electric current flowing through the current supply level circuit.
2. The circuit for driving an LED of claim 1 , further comprising a global enable transistor configured to turn the LED progressively on and/or off during any selective time period.
3. The circuit for driving an LED of claim 2 , wherein the global enable transistor is electrically connected in series with the LED.
4. The circuit for driving an LED of claim 1 , wherein each current supply level circuit includes a drive current load circuit configured to control a time for when the drive current transistor receives a first voltage level which sets the amount of electric current flowing through the current supply level circuit.
5. The circuit for driving an LED of claim 4 , wherein the drive current load circuit includes:
a first signal storage capacitor and a second signal storage capacitor, each signal storage capacitor configured to store a voltage level,
a first load transistor configured to control a transfer of the first voltage level from an external source to the first signal storage capacitor, and
a second load transistor configured to control the transfer of the first voltage level from the first signal storage capacitor to the second signal storage capacitor.
6. The circuit for driving an LED of claim 4 , wherein the drive current load circuit further includes a reset transistor configured to discharge the first voltage level from the second signal storage capacitor.
7. The circuit for driving an LED of claim 1 , further comprising a test enable transistor configured to control the flow of electric current from an external source through the current supply level circuits during a test of the circuit for driving an LED.
8. The circuit for driving an LED of claim 1 , wherein each current supply level circuit is electrically connected in series with the LED and in parallel with the other current supply level circuits.
9. The circuit for driving an LED of claim 1 , wherein the circuit enable transistor, the drive current transistor, and the gain control transistor are electrically connected in series with one another.
10. The circuit for driving an LED of claim 1 , wherein the circuit enable transistor, the drive current transistor, and the gain control transistor are each N-channel metal oxide semiconductor field effect transistors.
11. The circuit for driving an LED of claim 1 , wherein the circuit enable transistor, the drive current transistor, and the gain control transistor are each P-channel metal oxide semiconductor field effect transistors.
12. The circuit for driving an LED of claim 1 , wherein a maximum amount of electric current that flows through the current supply level circuit varies according to a size of the drive current transistor.
13. The circuit for driving an LED of claim 1 , wherein the LED is an infrared LED configured to emit radiation having an apparent temperature and a total amount of electric current flowing through the current supply level circuits varies non-linearly according to the apparent temperature.
14. The circuit for driving an LED of claim 1 , further comprising a current mirror circuit including a first transistor and a second transistor connected in a current mirror configuration such that electric current flowing through the LED also flows through the first transistor and electric current flowing through the current supply level circuits also flows through the second transistor.
15. A circuit for driving a light emitting diode (LED) to display a portion of a frame for a sequence of frames, the circuit comprising:
a plurality of current supply level circuits, each current supply level circuit configured to control a different amount of electric current flowing through the LED, each current supply level circuit including:
a circuit enable transistor configured to enable current flow through the current supply level circuit,
a drive current transistor configured to control an amount of electric current flowing through the current supply level circuit,
a gain control transistor configured to control a range of the amount of electric current flowing through the current supply level circuit, and
a drive current load circuit configured to receive a first voltage level which sets the amount of electric current flowing through the current supply level circuit for a next frame and output a second voltage level to the drive current transistor to set the amount of electric current flowing through the current supply level circuit for a current frame.
16. The circuit for driving an LED of claim 15 , wherein the drive current load circuit includes:
a first signal storage capacitor configured to store the first voltage level,
a second signal storage capacitor configured to store the second voltage level,
a first load transistor configured to control a transfer of the first voltage level from an external source to the first signal storage capacitor, and
a second load transistor configured to control the transfer of the first voltage level from the first signal storage capacitor to the second signal storage capacitor so that the first voltage level is stored as the second voltage level.
17. The circuit for driving an LED of claim 16 , wherein the drive current load circuit further includes a reset transistor configured to discharge the second voltage level from the second signal storage capacitor.
18. A circuit for driving an infrared (IR) light emitting diode (LED) configured to emit radiation having an apparent temperature, the circuit comprising:
a plurality of current supply level circuits, each current supply level circuit configured to control a different amount of electric current flowing through the IR LED such that each current supply level circuit controls the electric current flowing through the IR LED for a different range of apparent temperatures, each current supply level circuit including:
a circuit enable transistor configured to enable current flow through the current supply level circuit,
a drive current transistor configured to control an amount of electric current flowing through the current supply level circuit, and
a gain control transistor configured to control a range of the amount of electric current flowing through the current supply level circuit.
19. The circuit for driving an IR LED of claim 18 , wherein each current supply level circuit is electrically connected in series with the IR LED and in parallel with the other current supply level circuits.
20. The circuit for driving an IR LED of claim 18 , wherein the circuit enable transistor, the drive current transistor, and the gain control transistor are electrically connected in series with one another.