Image reading method and image reading apparatus

• US 5,946,427 A
• Filed: 07/31/1995
• Issued: 08/31/1999
• Est. Priority Date: 12/09/1994
• Status: Expired due to Term

• Current Assignee: Dosa Advances LLC (Intellectual Ventures LLC)
• Original Assignee: Fujitsu Limited
• Inventors: Kanemitsu, Norio
• Primary Examiner(s): Couso, Jose L.
• Assistant Examiner(s): Do, Anh Hong
• Application Number:
  US08/509,236
• Time in Patent Office: 1,492 Days
• Field of Search: 382/162, 382/165, 382/312, 358/500, 358/509, 358/510, 358/540, 359/227, 359/292, 359/297, 356/420, 356/425, 356/402
• US Class Current: 382/312
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks

Abstract

An image reading method and apparatus enable a high-speed, efficient reading of a multicolor image and a monochromatic image. The image reading apparatus has a color image pickup unit, a first light source and a second light source. An output switching unit selectively switches to either a first output state, where plural kinds of read information from the color image pickup unit are all output as a result of an image reading, or a second output state, where only one kind of read information among the plural kinds of read information from the color image pickup unit is selected to be output as a result of an image reading. A lighting control unit controls lighting conditions of the first light source and the second light source. A switching control unit controls a switching condition of the output switching unit.

Claims

1. An image reading method, for a color image reading system in which a multicolor original image and a monochromatic original image may be selectively read, comprising the steps of:

providing a shared color image pickup unit for reading said multicolor original image at plural different wavelengths based on blue, green and red primary colors of light and outputting plural kinds of image information as the result of the multicolor image reading, said shared color image pickup unit being adapted for reading said monochromatic original image at the wavelength of one of said blue, green and red primary colors of light and outputting one kind of said image information respectively corresponding to the result of the monochromatic image reading;

providing a white light source for radiating onto said multicolor original image a white light containing said plural wavelengths of said blue, green and red primary colors of light;

providing a monochromatic light source for radiating onto said monochromatic original image a monochromatic light containing the wavelength of said one of said blue, green and red primary colors of light;

selectively lighting only said white light source to radiate only said white light on said multicolor original image, or lighting both said white and monochromatic light sources to radiate both said white and monochromatic lights on said monochromatic original image;

selectively obtaining said image information corresponding to the multicolor image reading or obtaining said image information corresponding to the monochromatic image reading;

providing plural photodiodes for receiving a reflected light from said multicolor image or said monochromatic image and storing electric charges depending on a quantity of the reflected light to said shared color image pickup unit, and outputting the electric charges stored in said plural photodiodes as the image information; and

setting a time required to store the electric charges in said plural photodiodes during the monochromatic image reading, where both said white light source and said monochromatic light source are lit, shorter than a time required to store the electric charges in said plural photodiodes during the multicolor image reading where only said white light source is lit.

2. An image reading method according to claim 1, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is a same as that of said one primary color of said white light.

3. An image reading method according to claim 1, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is set on the basis of a spectral sensitivity characteristic of said shared color image pickup unit and emission characteristics of said white and monochromatic light sources.

4. An image reading method according to claim 1, wherein said monochromatic light to be radiated by said monochromatic light source is a green light.

5. An image reading apparatus for selectively reading a multicolor original image or a monochromatic original image, comprising:

a shared color image pickup unit for reading said multicolor original image at plural different wavelengths based on blue, green and red primary colors of light and for outputting plural kinds of image information as the result of the multicolor image reading, said shared color image pickup unit being adapted for reading said monochromatic original image at the wavelength of one of said blue, green and red primary colors of light and for outputting one kind of said image information respectively corresponding to the result of the monochromatic image reading;

a white light source for radiating onto said multicolor original image a white light containing said plural wavelengths of all of said blue, green and red primary colors of light;

a monochromatic light source for radiating onto said monochromatic original image a monochromatic light containing the wavelength of said one primary color of light;

a multicolor/monochrome output-mode switching unit adapted to selectively assume a multicolor output mode in which said switching unit allows all of said different kinds of image information according to the multicolor image reading from said shared color image pickup unit to be output as multicolor image information for subsequent image processing, and a monochromatic output mode in which said switching unit allows only said one kind of image information according to the monochromatic image reading from said shared color image pickup unit to be output as monochromatic image information for subsequent image processing;

a lighting control unit for rendering only said white light source to be turned on with only said monochromatic light source to be turned off during the multicolor image reading or rendering both said white and monochromatic lights turned on during the monochromatic image reading; and

an output-mode-switching control unit for rendering said output-mode switching unit to assume said multicolor output mode during the multicolor image reading or to assume said monochromatic output mode during the monochromatic image reading;

said shared color image pickup unit having plural photodiodes for receiving a reflected light from said multicolor original image or said monochromatic original image, storing electric charges depending on a quantity of the reflected light, and outputting the electric charges stored in said plural photodiodes as the image information;

said color image pickup unit further having a storing time control unit for controlling a time required to store the electric charges in said plural photodiodes;

said storing time control unit being adapted to set a time required to store the electric charges during the monochromatic image reading, where said white light source and said monochromatic light source are lit, shorter than a time required to store the electric charges during the multicolor image reading where only said white light source is lit.

6. An image reading apparatus according to claim 5, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is the same as that of said one primary color of said white light.

7. An image reading apparatus according to claim 5, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is set on the basis of a spectral sensitivity characteristic of said shared color image pickup unit and emission characteristics of said white and monochromatic light sources.

8. An image reading apparatus according to claim 5, wherein said monochromatic light to be radiated by said monochromatic light source is a green light.

9. An image reading method, for a color image reading system in which multicolor image reading and monochromatic image reading may be selectively carried out, comprising the steps of:

radiating on an original image, if said original image is of monochrome, both a white light containing different wavelengths of all of said blue, green and red colors of light from a white light source and a monochromatic light containing the wavelength of one of said blue, green and red colors from a monochromatic light source, or radiating on said original image, if said original is of multicolor, only said white light from the white light source;

reading said original image at the wavelengths of said blue, green and red colors of light using a shared color image pickup unit, if said original image is of multicolor, and then rendering the shared color image pickup unit to output different kinds of image information respectively corresponding to the result of the multicolor image reading, or reading said original image, if said original image is monochromatic, at the wavelength of said one color of light using the shared color image pickup unit, if said original image is monochromatic, and then rendering the shared color image pickup unit to output one kind of image information corresponding to the result of the monochromatic image reading; and

selecting one between the multicolor image reading and the monochromatic image reading in accordance with whether said original image is of multicolor or monochrome using a lighting control unit and a multicolor/monochrome output-mode switching unit; and

said selecting of image reading including rendering only the monochromatic light source to be turned off with the white light source to be turned on during the multicolor image reading or rendering both the white and monochromatic light sources to be turned on during the monochromatic image reading;

said selecting of image reading further including rendering the multicolor/monochrome output-mode switching unit to assume a multicolor output mode such that all of said different kinds of image information according to the multicolor image reading are allowed to be output from the shared color image pickup unit as multicolor image information for subsequent image processing or to assume a monochromatic output mode such that only said one kind of image information according to the monochromatic image reading is allowed to be output from the shared color image pickup unit as monochromatic image information for subsequent image processing.

10. An image reading method according to claim 9, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is the same as that of said one primary color of said white light.

11. An image reading method according to claim 9, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is set on the basis of a spectral sensitivity characteristic of said shared color image pickup and emission characteristics of said white and monochromatic light sources.

12. An image reading method according to claim 9, wherein said monochromatic light to be radiated by said monochromatic light source is a green light.

13. An image reading method according to claim 9, wherein said shared color image pickup unit has plural photodiodes for receiving a reflected light from said multicolor original image or said monochromatic color image and storing electric charges commensurate with a quality of the reflected light, and outputs said electric charges stored in said plural photodiodes as said image information, said shared color image pickup unit further having a storing time control unit for controlling a time required to store the electric charges in said plural photodiodes, setting said time required to store said electric charges at the time of reading of said monochromatic original image where both said white and monochromatic light sources are turned on for a time shorter than that of reading of said multicolor original image where only said white light source is turned on.

14. An image reading apparatus comprising:

a shared color image pickup unit for reading a multicolor original image at different wavelengths of blue, green and red colors of light and outputting different kinds of image information respectively corresponding to the result of multicolor image reading, said shared color image pickup unit being adapted for reading a monochromatic original image at the wavelength of one of said blue, green and red colors of light and outputting one kind of said image information corresponding to the result of monochromatic image reading;

a white light source for radiating a white light containing the wavelengths of all of said blue, green and red colors of light on said multicolor original image;

a monochromatic light source for radiating a monochromatic light containing the wavelength of said one color of light;

a multicolor/monochrome output-mode switching unit adapted to selectively assume a multicolor output mode in which said switching unit allows all of said different kinds of image information according to the multicolor image reading from said shared color image pickup unit to be output as multicolor image information for subsequent image processing, and a monochromatic output mode in which said switching unit allows only said one kind of image information according to the monochromatic image reading from said shared color image pickup unit to be output as monochromatic image information for subsequent image processing;

a lighting control unit for rendering only said monochromatic light source to be turned off with only said white light source to be turned on during the multicolor image reading or for rendering both said white and monochromatic light sources to be turned on during the monochromatic image reading; and

an output-mode-switching control unit for rendering said output-mode switching unit to assume said multicolor output mode during the multicolor image reading or to assume said monochromatic output mode during the monochromatic image reading.

15. An image-reading apparatus according to claim 14, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is the same as that of said one primary color of said white light.

16. An image reading apparatus according to claim 14, wherein the wavelength of said monochromatic light to be radiated by said monochromatic light source is set on the basis of a spectral sensitivity characteristic of said shared color image pickup and emission characteristics of said white and monochromatic light sources.

17. An image reading apparatus according to claim 14, wherein said monochromatic light to be radiated by said monochromatic light source is a green light.

18. An image reading apparatus according to claim 14, wherein said shared color image pickup unit has plural photodiodes for receiving a reflected light from said multicolor original image or said monochromatic color image and storing electric charges commensurate with a quality of the reflected light, and outputs said electric charges stored in said plural photodiodes as said image information, said shared color image pickup unit further having a storing time control unit for controlling a time required to store said electric charges in said plural photodiodes and setting said time required to store said electric charges at the time of reading of said monochromatic original image where both said white and monochromatic light sources are turned on for a time shorter than that of reading of said multicolor original image where only said white light source is turned on.