System and method for adaptive digital ramp current control

• US 7,830,560 B2
• Filed: 01/31/2007
• Issued: 11/09/2010
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Allman, Stuart, Smith, Kenneth K., Johnson, Craig T.
• Primary Examiner(s): Grant, II; Jerome
• Application Number:
  US11/700,458
• Publication Number:
  US 20080180042A1
• Time in Patent Office: 1,378 Days
• Field of Search: 358/509, 358/510, 358/513, 358/520, 358/475, 358/480, 358/482, 347/128, 347/129, 347/130, 347/135, 347/224, 347/255, 250/201.9, 250/205, 250/552, 250/559.06, 250/214.LA, 250/214.AG, 250/227.21
• US Class Current: 358/475
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 47/16 by timing means
• 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: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

An adaptive digital ramp current control system comprises a digital current ramp controller configured to digitally ramp a current level supplied to at least one light emitting diode (LED) according to a predetermined ramp profile, the ramp profile comprising at least one intermediate current level step between a minimum current level and a maximum current level.

Claims

1. An adaptive digital ramp current control method, comprising:

automatically digitally ramping a current level supplied to a light emitting diode (LED) according to a predetermined ramp profile, the ramp profile comprising at least one intermediate current level step between a minimum current level and a maximum current level; and

,

holding the at least one intermediate current level for a predetermined time period based on the ramp profile.

2. The method of claim 1 further comprising automatically adjusting the ramp profile.

3. The method of claim 1 wherein ramping comprises digitally incrementing from the minimum current level to the at least one intermediate current level.

4. The method of claim 1 wherein ramping comprises digitally decrementing from the maximum current level to the at least one intermediate current level.

5. The method of claim 1 further comprising storing the ramp profile to a memory disposed in an imaging system.

6. The method of claim 1 further comprising generating the ramp profile based on at least one of a radio frequency (RF) emission and a ground bounce measurement associated with actuation of the LED.

7. The method of claim 1 further comprising automatically modifying the ramp profile based on at least one of a RF emission and a ground bounce measurement associated with actuation of the LED.

8. An adaptive digital ramp current control system, comprising:

a digital current ramp controller configured to automatically digitally ramp a current level supplied to at least one light emitting diode (LED) according to a predetermined ramp profile, the ramp profile comprising at least one intermediate current level step between a minimum current level and a maximum current level; and

,

a compensation module configured to generate and/or automatically modify the ramp profile based on at least one of a radio frequency (RF) emission and a ground bounce measurement associated with actuation of the at least one LED.

9. The system of claim 8 wherein the digital current ramp controller is configured to hold the at least one intermediate current level for a predetermined time period based on the ramp profile.

10. The system of claim 8 wherein the digital current ramp controller is configured to incrementally ramp the current level from the minimum current level to the at least one intermediate current level.

11. The system of claim 8 wherein the digital current ramp controller is configured to decrementally ramp the current level from the maximum current level to the at least one intermediate current level.

12. The system of claim 8 wherein the digital current ramp controller is disposed on an application specific integrated circuit (ASIC).

13. An imaging system, comprising:

a photosensitive element for generating a scanned image of an object;

at least one light emitting diode (LED) for illuminating the object; and

a digital current ramp controller configured to automatically digitally ramp a current level supplied to the at least one (LED) according to a predetermined ramp profile, the ramp profile comprising at least one intermediate current level step between a minimum current level and a maximum current level,

wherein the digital current ramp controller is configured to hold the at least one intermediate current level for a predetermined time period based on the ramp profile.

14. The system of claim 13 wherein the digital current ramp controller is at least partially integrated into an application specific integrated circuit (ASIC).

15. The system of claim 13 further comprising a compensation module configured to dynamically modify the ramp profile.

16. The system of claim 13 further comprising a compensation module configured to automatically generate the ramp profile based on at least one of a radio frequency (RF) emission and a ground bounce measurement associated with actuation of the at least one LED.