Pulse-width modulated drivers for light-emitting units of scanning mechanism

• US 7,102,801 B2
• Filed: 04/26/2003
• Issued: 09/05/2006
• Est. Priority Date: 04/26/2003
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Eaton, William, Bliley, Paul D., Meyer, William D.
• Primary Examiner(s): Lee, Cheukfan
• Application Number:
  US10/424,497
• Publication Number:
  US 20040212847A1
• Time in Patent Office: 1,228 Days
• Field of Search: 358/509, 358512-514, 358/505, 358/506, 358/475, 358/482, 358/483, 358/474, 358/497, 250/226, 250/208.1, 250234-236, 250/216, 250/227.2, 250/578.1, 362/800, 362/230, 362/231, 362611-613, 315/291, 315/300, 315/312, 382/312, 382/318, 382/319, 399/220, 399/4, 399/211, 399/212
• US Class Current: 358/509
• CPC Class Codes: H04N 1/484 with sequential colour illumination of the original
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A scanning mechanism of one embodiment of the invention is disclosed that includes light-emitting units, an integrating detector, and pulse-width modulated (PWM) drivers. Each light-emitting unit can emit colored light corresponding to a color of a color space. The integrating detector can detect the colored light emitted by the light-emitting units as reflected off a surface by integrating the colored light detected over a period of time. Each PWM driver can turn on a corresponding light-emitting unit at a duty cycle.

Claims

1. A scanning mechanism comprising:

a plurality of light-emitting units to each emit colored light;

a detector to measure a plurality of intensities of the colored light emitted by the plurality of the light-emitting units; and

,

a plurality of pulse-width modulated (PWM) drivers, each of the plurality of the PWM drivers to turn on a corresponding one of the plurality of the light-emitting units at a duty cycle based on a difference between corresponding ones of the plurality of the intensities of the colored light measured and a plurality of reference light intensities.

2. The scanning mechanism of claim 1, wherein the plurality of light-emitting units comprise a plurality of light-emitting diodes (LED'"'"'s).

3. The scanning mechanism of claim 1, wherein the plurality of light-emitting units comprise a red light-emitting unit, a green light-emitting unit, and a blue light-emitting unit, corresponding to red, green, and blue colors of a red-green-blue (RGB) color space.

4. The scanning mechanism of claim 1, wherein the plurality of light-emitting units comprise a white light-emitting unit, corresponding to a white color of a grayscale color space.

5. The scanning mechanism of claim 1, wherein the plurality of PWM drivers turn on corresponding ones of the plurality of the light-emitting units during different periods of time, such that at any time at most one of the light-emitting units is emitting light.

6. The scanning mechanism of claim 1, wherein the plurality of PWM drivers turn on corresponding ones of the plurality of the light-emitting units at the duty cycles such that ones of the plurality light-emitting units output the colored light at equal effective intensities over a period of time.

7. The scanning mechanism of claim 1, wherein each of the plurality of the PWM drivers comprises:

a control register storing a value corresponding to the duty cycle in accordance with which a corresponding one of the plurality of the light-emitting units is to emit light; and

,

a transistor interfacing the control register to the corresponding light-emitting unit.

8. The scanning mechanism of claim 7, wherein the PWM driver outputs pulses having a duty cycle corresponding to the value stored by the control register.

9. The scanning mechanism of claim 7, wherein the plurality of PWM drivers comprise at least one controller to turn on the light-emitting units at the duty cycles based on the values stored by the control registers.

10. The scanning mechanism of claim 9, wherein the at least one controller comprises one controller controlling all the light-emitting units.

11. The scanning mechanism of claim 9, wherein the at least one controller comprises a plurality of controllers corresponding to the plurality of light-emitting units.

12. The scanning mechanism of claim 1, further comprising an integrated circuit (IC) within which the PWM drivers are implemented.

13. The scanning mechanism of claim 12, wherein each driver is communicatively connected to an input/output (IO) of the IC, such that the light-emitting unit corresponding to the driver is also communicatively connected to the IO of the IC.

14. The scanning mechanism of claim 13, wherein the IO comprises a general-purpose IO (GPIO).

15. The scanning mechanism of claim 12, wherein the IC comprises an application-specific IC (ASIC).

16. A scanning mechanism comprising:

a plurality of light-emitting units to emit colored light;

a detector to measure a plurality of intensities of the colored light emitted by the plurality of the light-emitting units as reflected off a surface; and

,

means for turning on ones of the plurality of the light-emitting units at duty cycles based on a variance between corresponding ones of the plurality of the intensities of the colored light measured and a plurality of reference light intensities.

17. The scanning mechanism of claim 16, wherein the means comprises, for each light-emitting unit, a control register storing a value corresponding to the duty cycle in accordance with which the corresponding light-emitting unit is to emit light.

18. The scanning mechanism of claim 16, wherein the means comprises an integrated circuit (IC).

19. A scanning device comprising:

a plurality of scanning mechanisms corresponding to a width of media, each scanning mechanism for scanning a portion of the width of the media by successively turning on a plurality of light-emitting units corresponding to colors of a color space at different duty cycles; and

,

an advance mechanism to advance the media over a length of the media relative to the plurality of scanning mechanisms such that the plurality of scanning mechanisms scan the length of the media.

20. The scanning device of claim 19, wherein each scanning mechanism comprises a plurality of pulse-width modulated (PWM) drivers to turn on the light-emitting units at the different duty cycles.

21. The scanning device of claim 19, wherein each scanning mechanism comprises an integrating detector to detect colored light emitted by the light-emitting units as reflected off the portion of the width of the media over the period of time.

22. The scanning device of claim 19, wherein each scanning mechanism generates a plurality of pulses corresponding to the plurality of light-emitting units having the different duty cycles.

23. The scanning device of claim 19, wherein the advance mechanism physically advances the media past the plurality of scanning mechanisms, which are stationary.

24. The scanning device of claim 19, wherein the advance mechanism physically advances the plurality of scanning mechanisms past the media, which is stationary.

25. The scanning device of claim 19, wherein the scanning device is a stand-alone scanner.

26. The scanning device of claim 19, wherein the scanning device is part of a multi-function device (MFD).

27. A method comprising:

turning on a light-emitting unit for a period of time according to a duty cycle based on a value stored in a control register;

detecting an effective light intensity of light emitted by the light-emitting unit as reflected off a nominal surface; and

,

adjusting the value stored in the control register based on a variance between the effective light intensity and a reference light intensity.

28. The method of claim 27, further comprising:

during each of a number of successive periods of time equal to a number of additional of the light-emitting units, turning on one of the additional the light-emitting unit for a period of time according to a duty cycle based on a value stored in a corresponding one of additional of the control register;

detecting an effective light intensity of light emitted by the one of the additional of the light-emitting unit as reflected off a nominal surface; and

adjusting the value stored in the corresponding one of the additional of the control register based on a variance between the effective light intensity and a reference light intensity corresponding to the one of the additional of the light-emitting unit.