Illumination source for a scanner having a plurality of solid state lamps and a related method

• US 6,299,329 B1
• Filed: 02/23/1999
• Issued: 10/09/2001
• Est. Priority Date: 02/23/1999
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Andersen, Eric L., Mui, Paul K., Miller, Craig L.
• Primary Examiner(s): Sember, Thomas M.
• Assistant Examiner(s): DELGIZZI, RONALD ERNEST
• Application Number:
  US09/256,618
• Time in Patent Office: 959 Days
• Field of Search: 362/227, 362/800, 362/231, 362/230
• US Class Current: 362/227
• CPC Class Codes: H04N 1/02815 Means for illuminating the original, not specific to a particular type of pick-up head
• CPC Class Codes: H04N 1/02865 using an array of light sources or a combination of such arrays, e.g. an LED bar
• CPC Class Codes: H04N 1/48 Picture signal generators for halftone screening H04N1/52
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A first embodiment of an illumination source including red LEDs, green LEDs, and blue LEDs provides illumination for a scanner. The LEDs are arranged in an array to generate spectrally and spatially substantially uniform illumination on the surface of an object, such as printed media, which is to be scanned. The arrangement of LEDs includes a plurality of groups of three LEDs. Each group of LEDs includes a red LED, a green LED, and a blue LED. The LEDs of like colors are connected in series. Power is supplied to the three groups of series connected LEDs by three current sources. The three current sources are each configured to supply a constant current to one of the groups of series connected LEDs. Each current source supplies a magnitude of current so that the resulting light provides substantially uniform illumination on the printed media. A second embodiment of the illumination source includes LEDs that can each generate light having a substantially uniform energy spectrum over the range of visible light frequencies. A third embodiment of the illumination source includes a plurality of groups of four LEDs. Each of the groups of LEDs includes a red LED, a green LED, a blue LED, and a yellow LED.

Claims

1. An illumination source for use in a scanner to illuminate an object for scanning, comprising:

a plurality of white light solid state lamps to each generate light having a substantially uniform spectrum over a range of visible light frequencies for illuminating the object with power contemporaneously supplied to the plurality of the white light solid state lamps.

2. An illumination source for use in a scanner to illuminate an object for scanning, comprising:

a plurality of solid state lamps to generate light of a plurality of colors and configured to form composite light having a substantially uniform spectrum over a range of visible light frequencies for illuminating the object with power contemporaneously supplied to the plurality of the solid state lamps.

3. The illumination source as recited in claim 2, wherein:

each of the solid state lamps includes a LED.

4. The illumination source as recited in claim 3, wherein:

the plurality of the LEDs includes a plurality of groups of the LEDs with each of the groups including a first LED for providing a first color, a second LED for providing a second color, and a third LED for providing a third color.

5. The illumination source as recited in claim 4, wherein:

the first LED includes a configuration to emit red light

the second LED includes a configuration to emit green light; and

the third LED includes a configuration to emit blue light.

6. The illumination source as recited in claim 5 wherein:

each of the groups includes a fourth LED to emit yellow light, where the first LED, the second LED, the third LED, and the fourth LED include a configuration to generate the light having the substantially uniform spectrum over the range of visible light frequencies with the power contemporaneously supplied to the first LED, the second LED, the third LED, and the fourth LED.

7. A scanner for scanning images formed on an object to be scanned, comprising:

a scanning mechanism including a sensor for measuring light reflected from the object to be scanned; and

an illumination source for illuminating the object to be scanned including a plurality of solid state lamps to generate the light of a plurality of colors and configured to form composite light having a substantially uniform spectrum over a range of visible light frequencies with power contemporaneously supplied to the plurality of the solid state lamps.

8. The scanner as recited in claim 7 wherein:

each of the solid state lamps includes a LED.

9. The scanner as recited in claims 8, wherein:

the plurality of the LEDs includes a plurality of groups of LEDs with each of the groups including a first LED for providing a first color, a second LED for providing a second color, and a third LED for providing a third color.

10. The scanner as recited in claim 9, wherein:

the first LED includes a configuration to emit red light the second LED includes a configuration to emit green light; and

the third LED includes a configuration to emit blue light.

11. The scanner as recited in claim 10, wherein:

each of the groups includes a fourth LED to emit yellow light, where the first LED, the second LED, the third LED, and the fourth LED include a configuration to generate the light having the substantially uniform spectrum over the range of visible light frequencies with the power contemporaneously supplied to the first LED, the second LED, the third LED, and the fourth LED.

12. A method for using an illumination source, including a plurality of solid state lamps, in a scanner configured to scan an object, comprising:

applying power contemporaneously to each of the solid state lamps to generate light from the solid state lamps of a plurality of colors;

combining the light of the plurality of colors to form composite light having a substantially uniform spectrum over a range of visible light frequencies; and

guiding the composite light to illuminate the surface of the object.

13. The method as recited in claim 12, wherein:

the plurality of the solid state lamps includes a plurality of groups of solid state lamps with each of the groups including a first solid state lamp for providing a first color, a second solid state lamp for providing a second color, and a third solid state lamp for providing a third color.

14. The method as recited in claim 13, wherein:

the first solid state lamp, the second solid state lamp, and the third solid state lamp each include a LED.

15. The method as recited in claim 14, wherein:

the first LED includes a configuration to emit red light

the second LED includes a configuration to emit green light; and

the third LED includes a configuration to emit blue light.

16. The method as recited in claim 15 wherein:

each of the groups includes a fourth LED to emit yellow light where the first LED, the second LED, the third LED, and the fourth LED include a configuration to generate the light having the substantially uniform spectrum over the range of visible light frequencies with the power contemporaneously supplied to the first LED, the second LED, the third LED, and the fourth LED.

17. A scanner for scanning images formed on an object to be scanned, comprising:

a scanning mechanism including a sensor for measuring light reflected from the object to be scanned; and

an illumination source for illuminating the object to be scanned including a plurality of white light solid state lamps to each generate the light having a substantially uniform spectrum over a range of visible light frequencies with power supplied to the plurality of the white light solid state lamps.