Method and apparatus for sensing image

• US 6,765,703 B1
• Filed: 09/27/2000
• Issued: 07/20/2004
• Est. Priority Date: 09/27/2000
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Tec Corporation (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Tec Corporation (Toshiba Corporation)
• Inventors: Watanabe, Kouichi
• Primary Examiner(s): Lee, Cheukfan
• Application Number:
  US09/670,621
• Time in Patent Office: 1,392 Days
• Field of Search: 358/514, 358/513, 358/512, 358/505, 358/506, 358/500, 358/515, 358/483, 358/445, 358/482, 341/155, 341/156, 341/141, 250/208.1, 250/234-236, 348/272, 348/273
• US Class Current: 358/514
• CPC Class Codes: H04N 1/40056 Circuits for driving or energising particular reading heads or original illumination means H04N1/401, H04N1/407 take precedence
• CPC Class Codes: H04N 1/486 with separate detectors, each detector being used for one specific colour component

Abstract

This invention uses a 4-line color CCD sensor including four line sensors Y, R, G, and B. In a low-speed color read mode, outputs from these sensors are processed by A/D converters and subsequent processing units provided in one-to-one correspondence with the sensors. In a high-speed monochromatic read mode, an output from the Y sensor is divisionally processed by using A/D converters and subsequent processing units provided in one-to-one correspondence not only with the Y sensor but also with the other R, G, and B sensors. This provides an image reading apparatus usable in both the high-speed monochromatic mode and the low-speed color mode and capable of achieving high speed, high accuracy, and low cost.

Claims

1. An image reading apparatus comprising:

a line sensor unit including a monochromatic sensor for outputting a one-line signal by dividing the signal into a plurality of signals, and a plurality of color sensors;

a mode setting circuit for setting one of a monochromatic mode and a color mode;

a monochromatic analog-to-digital converter which corresponds to said monochromatic sensor and receives signals and performs analog-to-digital conversion for the received signals;

a plurality of color analog-to-digital converters which correspond to said plurality of color sensors and receive signals and perform analog-to-digital conversion for the received signals; and

a selector for distributing, when the monochromatic mode is set in said mode setting circuit, the plurality of output signals from said monochromatic sensor to said monochromatic analog-to-digital converter and said color analog-to-digital converters to cause said monochromatic and color analog-to-digital converters to perform analog-to-digital conversion for the signals.

2. An apparatus according to claim 1, wherein when the color mode is set in said mode setting circuit, said selector supplies output signals from said color sensors to corresponding ones of said color analog-to-digital converters to cause said color analog-to-digital converters to perform analog-to-digital conversion for the signals.

3. An apparatus according to claim 2, wherein when the color mode is set in said mode setting circuit, said line delaying/rearranging units receive the digital signals, which are output from said color sensors and subjected to analog-to-digital conversion by said color analog-to-digital converters, and output the digital signals by rearranging the signals.

4. An apparatus according to claim 1, further comprising line delaying/rearranging units which correspond to said monochromatic analog-to-digital converter and said color analog-to-digital converters, and receive output digital signals, delay the signals in units of lines, and output the digital signals by rearranging the signals,

wherein when the monochromatic mode is set in said mode setting circuit, said line delaying/rearranging units receive the digital signals, which are divisionally output from said monochromatic sensor and subjected to analog-to-digital conversion by said monochromatic analog-to-digital converter and said color analog-to-digital converters, and output the digital signals by rearranging the signals.

5. An apparatus according to claim 4, further comprising a read direction setting unit for setting an original read direction to one of a forward direction and a reverse direction,

wherein in accordance with one of the forward direction and the reverse direction set in said read direction setting unit, said line delaying/rearranging units switch a line delaying and pixel rearranging process in the forward direction and a line delaying and pixel rearranging process in the reverse direction.

6. An apparatus according to claim 1, wherein the number of divided outputs from said monochromatic sensor is larger than the number of divided outputs from said color sensors.

7. An apparatus according to claim 6, wherein said monochromatic sensor divides the signal by a number four times the number of said color sensors and outputs the divided signals.

8. An apparatus according to claim 1, wherein said monochromatic sensor is placed closer to one end face of said sensor unit than said color sensors.

9. An apparatus according to claim 1, wherein said sensor unit is set such that when an original is read in a forward direction, said monochromatic sensor reads a position on the original, which leads positions read by said color sensors.

10. An image reading method of performing image processing by using a line sensor unit including a monochromatic sensor for outputting a one-line signal by dividing the signal into a plurality of signals, and a plurality of color sensors, a monochromatic analog-to-digital converter which corresponds to said monochromatic sensor and receives signals and performs analog-to-digital conversion for the received signals, and a plurality of color analog-to-digital converters which correspond to said plurality of color sensors and receive signals and perform analog-to-digital conversion for the received signals,

wherein when a monochromatic mode rather than a color mode is set, the plurality of output signals from said monochromatic sensor are distributed to said monochromatic analog-to-digital converter and said color analog-to-digital converters to cause said monochromatic and color analog-to-digital converters to perform analog-to-digital conversion for the signals.

11. A method according to claim 10, wherein when the color mode is set, output signals from said color sensors are supplied to corresponding ones of said color analog-to-digital converters to cause said color analog-to-digital converters to perform analog-to-digital conversion for the signals.

12. A method according to claim 10, wherein line delaying/rearranging units corresponding to said monochromatic analog-to-digital converter and said color analog-to-digital converters are used to receive output digital signals, delay the signals in units of lines, and output the digital signals by rearranging the signals, and

when the monochromatic mode is set, only the divided output signals from said monochromatic sensor are used to rearrange digital signals subjected to analog-to-digital conversion by said monochromatic analog-to-digital converter and said color analog-to-digital converters.

13. A method according to claim 10, wherein when the color mode is set, the digital signals, which are output from said color sensors and subjected to analog-to-digital conversion by said color analog-to-digital converters, are rearranged by using said line delaying/rearranging units.

14. A method according to claim 10, wherein when an original read direction is set to one of a forward direction and a reverse direction, in accordance with one of the forward direction and the reverse direction set as the read direction, said line delaying/rearranging units switch a line delaying and pixel rearranging process in the forward direction and a line delaying and pixel rearranging process in the reverse direction.