Apparatus and method for pulsed L.E.D. illumination

• US 8,829,808 B1
• Filed: 10/08/2013
• Issued: 09/09/2014
• Est. Priority Date: 03/19/1998
• Status: Expired due to Fees

• Current Assignee: Lemaire Illumination Technologies LLC
• Original Assignee: LED Tech Development LLC
• Inventors: Lebens, Gary A., Bourn, Charles T., Lemaire, Charles A.
• Primary Examiner(s): Vu, Jimmy
• Application Number:
  US14/049,188
• Time in Patent Office: 336 Days
• Field of Search: 315152-159, 315/209.R, 315/225, 315/226, 315/291, 315/307, 315/308, 315/362
• US Class Current: 315/291
• CPC Class Codes: F21L 4/027 the light sources being a LED
• CPC Class Codes: F21Y 2101/00 Point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H04N 23/51 Housings
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/32 Pulse-control circuits
• CPC Class Codes: H05B 45/397 Current mirror circuits
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y10S 362/80 Light emitting diode
• CPC Class Codes: Y10S 362/802 Position or condition responsive switch

Abstract

An illumination source for a camera includes one or more LEDs, and an electrical circuit that selectively applies power from the DC voltage source to the LEDs, wherein the illumination source is suitable for handheld portable operation. In some embodiments, the electrical circuit further includes a control circuit for driving the LEDs with electrical pulses at a frequency high enough that light produced has an appearance to a human user of being continuous rather than pulsed, the control circuit changing a pulse characteristic to adjust a proportion of light output having the first characteristic color spectrum output to that having the second characteristic color spectrum output. Some embodiments provide an illumination source including a housing including one or more LEDs and a control circuit that selectively applies power from a source of electric power to the LEDs, thus controlling a light output color spectrum of the LEDs.

Claims

1. An apparatus comprising:

a casing;

a light-emitting diode mounted to the casing;

a DC voltage source that is mounted to the casing and having an amount of electrical power;

a user interface that receives input from a user; and

a control circuit, operably coupled to the user interface, the DC voltage source, and the light emitting diode, wherein the control circuit generates a series of pulses to drive the light-emitting diode to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user while maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies, and wherein the control circuit maintains the average intensity of the light from the light-emitting diode while minimizing power dissipation within the control circuit by not having a resistor in series with the light-emitting diode and the DC power source.

2. The apparatus of claim 1, wherein the first characteristic of the light from the light-emitting diode that is controlled by the control circuit based at least in part on the received input from the user is the average light intensity, wherein the apparatus is a handheld electronic device, and wherein the DC voltage source is a battery within the electronic device.

3. The apparatus of claim 1, wherein the first characteristic of the light from the light-emitting diode that is controlled by the control circuit based at least in part on the received input from the user is the average light intensity, wherein the apparatus is a flashlight, and wherein the DC voltage source is a battery within the electronic device.

4. The apparatus of claim 1, wherein the apparatus includes a camera.

5. The apparatus of claim 1, wherein a current amount and a pulse width of the pulses are both varied by the control circuit in order to adjust the first characteristic of light from the light-emitting diode.

6. The apparatus of claim 1, wherein a pulse energy of the pulses is varied by the control circuit in order to adjust the first characteristic of light from the light-emitting diode.

7. The apparatus of claim 1, wherein the control circuit includes a current mirror that changes an amount of current through the light-emitting diode based on a variable amount of control current applied to an input of the current minor.

8. An apparatus comprising:

a casing;

a light-emitting diode mounted to the casing;

a DC voltage source that is mounted to the casing and having an amount of electrical power;

a user interface that receives input from a user;

a control circuit, operably coupled to the user interface, the DC voltage source, and the light emitting diode, wherein the control circuit generates a series of pulses to drive the light-emitting diode to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user while maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies; and

a color detector that generates a feedback signal, wherein the control circuit is operably coupled to the color detector, and wherein the control circuit also controls the color of light from the light-emitting diode by adjusting an amount of current through the light-emitting diode based on the feedback signal.

9. The apparatus of claim 8, wherein the control circuit includes a current mirror that changes the amount of current through the light-emitting diode based on a variable amount of control current applied to an input of the current mirror.

10. An apparatus comprising:

a casing;

a light-emitting diode mounted to the casing;

a DC voltage source that is mounted to the casing and having an amount of electrical power;

a user interface that receives input from a user; and

a control circuit, operably coupled to the user interface, the DC voltage source, and the light emitting diode, wherein the control circuit generates a series of pulses to drive the light-emitting diode to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user while maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies and minimize power dissipation by not having a resistor in series with the light-emitting diode and the DC power source, and wherein the control circuit also controls a pulse width of the series of pulses applied to the light-emitting diode based on a measured light output intensity of the light-emitting diode.

11. A method for driving a light-emitting diode in a handheld device having a casing, a DC power source mounted to the casing, and a light-emitting diode mounted to the casing, the method comprising:

receiving input from a user; and

based on the received input, generating a series of pulses that drive the light-emitting diode to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user while maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies;

detecting a color of light from the light-emitting diode; and

generating a feedback signal based on the detected color of light from the light-emitting diode, wherein the generating of the series of pulses includes controlling the color of light from the light-emitting diode by adjusting an amount of current through the light-emitting diode based on the feedback signal.

12. The method of claim 11, wherein the generating of the series of pulses includes mirroring a current to change the amount of current applied from the pulses through the light-emitting diode based on a variable amount of current controlling the mirroring.

13. A method for driving a light-emitting diode in a handheld device having a casing, a DC power source mounted to the casing, and a light-emitting diode mounted to the casing, the method comprising:

receiving input from a user; and

based on the received input, generating a series of pulses that drive the light-emitting diode to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user while maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies, wherein the generating of the series of pulses maintains the average intensity of the light from the light-emitting diode while minimizing power dissipation by not having a resistor in series with the light-emitting diode and the DC power source.

14. The method of claim 13, wherein the generating of the series of pulses that drive the light-emitting diode to adjust the first characteristic of the light from the light-emitting diode that is controlled based at least in part on the received input from the user is the average light intensity, wherein the handheld device is a handheld electronic device, and wherein the DC voltage source is a battery within the electronic device.

15. The method of claim 13, wherein the generating of the series of pulses that drive the light-emitting diode to adjust the first characteristic of the light from the light-emitting diode that is controlled based at least in part on the received input from the user is the average light intensity, wherein the handheld device is a flashlight, and wherein the DC voltage source is a battery within the electronic device.

16. A method for driving a light-emitting diode in a handheld device having a casing, a DC power source mounted to the casing, and a light-emitting diode mounted to the casing, the method comprising:

receiving input from a user; and

based on the received input, generating a series of pulses that drive the light-emitting diode to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user while maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies while minimizing power dissipation by not having a resistor in series with the light-emitting diode and the DC power source, wherein the generating of the series of pulses also includes controlling a pulse width of the series of pulses that drive the light-emitting diode based on a measured light output intensity of the light-emitting diode, wherein the first characteristic of the light from the light-emitting diode that is controlled is the average light intensity, and wherein the DC voltage source is a battery within the handheld device.

17. An apparatus comprising:

a casing;

a light-emitting diode mounted to the casing;

a DC voltage source that is mounted to the casing and having an amount of electrical power;

a user interface that receives input from a user;

means for generating a series of pulses that drive the light-emitting diode based on the received input to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user;

means for maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies; and

means for detecting a color of light from the light-emitting diode; and

means for generating a feedback signal based on the detected color of light from the light-emitting diode, wherein the means for generating of the series of pulses includes means for controlling the color of light from the light-emitting diode using means for adjusting an amount of current through the light-emitting diode based on the feedback signal.

18. The apparatus of claim 17, wherein the means for generating of the series of pulses includes means for mirroring a current to change the amount of current applied from the pulses through the light-emitting diode based on a variable amount of current controlling the means for mirroring.

19. An apparatus comprising:

a casing;

a light-emitting diode mounted to the casing;

a DC voltage source that is mounted to the casing and having an amount of electrical power;

a user interface that receives input from a user;

means for generating a series of pulses that drive the light-emitting diode based on the received input to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user;

means for maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies, wherein the means for generating of the series of pulses maintains the average intensity of the light from the light-emitting diode while minimizing power dissipation by not having a resistor in series with the light-emitting diode and the DC power source.

20. The apparatus of claim 19, wherein the first characteristic of the light from the light-emitting diode that is adjusted based at least in part on the received input from the user is the average light intensity, wherein the apparatus is a handheld electronic device, and wherein the DC voltage source is a battery within the electronic device.

21. The apparatus of claim 19, wherein the first characteristic of the light from the light-emitting diode that is adjusted based at least in part on the received input from the user is the average light intensity, wherein the apparatus is a flashlight, and wherein the DC voltage source is a battery within the electronic device.

22. An apparatus comprising:

a casing;

a light-emitting diode mounted to the casing;

a DC voltage source that is mounted to the casing and having an amount of electrical power;

a user interface that receives input from a user;

means for generating a series of pulses that drive the light-emitting diode based on the received input to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user;

means for maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies while minimizing power dissipation by not having a resistor in series with the light-emitting diode and the DC power source, wherein the generating of the series of pulses also includes controlling a pulse width of the series of pulses that drive the light-emitting diode based on a measured light output intensity of the light-emitting diode, wherein the first characteristic of the light from the light-emitting diode that is controlled is the average light intensity, and wherein the DC voltage source is a battery within the handheld device.

23. A method for driving a light-emitting diode in a device having a casing, a DC power source mounted to the casing, and a light-emitting diode mounted to the casing, the method comprising:

receiving input from a user; and

based on the received input, generating a series of pulses that drive the light-emitting diode to adjust a first characteristic of light from the light-emitting diode based at least in part on the received input from the user while maintaining an average intensity of the light from the light-emitting diode as a voltage of the DC voltage source varies, wherein the generating of the series of pulses maintains the average intensity of the light from the light-emitting diode while minimizing power dissipation by not having a resistor in series with the light-emitting diode and the DC power source.

24. The method of claim 23, wherein the first characteristic of the light from the light-emitting diode that is adjusted based at least in part on the received input from the user is a color spectrum.

25. The method of claim 23, wherein the device includes a camera.