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US 8,264,747 B2Granted
Image reading device and image reading method
AssigneeRicoh Company, Ltd.
InventorsMasaki Nagase, Tohru Kanno
Life of this patent
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Abstract
In an image reading device, a sampling-and-holding circuit generates a plurality of analog image signals by sampling an image signal at each sampling-and-holding timing and holding sampled image signals for a predetermined amount of time, an analog-to-digital converting unit converts the analog image signals into a plurality of digital image signals at each sampling-and-holding timing, a phase regulating unit performs phase regulation of each sampling-and-holding timing based on corresponding digital image signals to obtain phase-regulated sampling-and-holding timing. The sampling-and-holding circuit generates the analog image signal at each phase-regulated sampling-and-holding timing.
Claims4
An image reading device comprising:
- a light source that illuminates an original;
- an image sensor that receives a light reflected from the original and outputs an image signal corresponding to the light in synchronization with an input of a timing signal at a plurality of timings;
- a timing generating unit that generates a sampling-and-holding timing based on the timing signals;
- a sampling-and-holding circuit that generates a plurality of analog image signals by sampling the image signal at each sampling-and-holding timing and holding sampled image signals for a predetermined amount of time, and outputs the analog image signals;
- an analog-to-digital converting unit that performs signal quantization of the analog image signals to obtain a plurality of digital image signals at each sampling-and-holding timing and outputs the digital image signals;
- a phase regulating unit that performs phase regulation of each sampling-and-holding timing based on corresponding digital image signals to obtain phase-regulated sampling-and-holding timing;
- and
- an image processing unit that performs image processing on the digital image signals obtained at an optimal phase-regulated sampling-and-holding timing,
- wherein the sampling-and-holding circuit generates the analog image signal at each phase-regulated sampling-and-holding timing,
- the image reading device further comprising a calculating unit that
- calculates an n-th mean value of the digital image signals at an n-th sampling-and-holding timing, an (n−1)-th mean value of the digital image signals at an (n−1)-th sampling-and-holding timing, and an (n+1)-th mean value of the digital image signals at an (n+1)-th sampling-and-holding timing,
- calculates a first difference between the n-th mean value and the (n−1)-th mean value, and a second difference between the n-th mean value and the (n+1)-th mean value,
- calculates a sum of the first difference and the second difference to obtain a sum of differences at the n-th sampling-and-holding timing, and
- repeats calculating the sum of differences at each sampling-and-holding timing,
- wherein the phase regulating unit selects a sampling-and-holding timing at which the sum of differences is minimum as the optimal sampling-and-holding timing.
12 more elements
An image reading method comprising:
- receiving a light reflected from the original and outputting an image signal corresponding to the light in synchronization with an input of a timing signal at a plurality of timings;
- generating a sampling-and-holding timing based on the timing signals;
- generating a plurality of analog image signals by sampling the image signal at each sampling-and-holding timing and holding sampled image signals for a predetermined amount of time and outputting the analog image signals;
- performing signal quantization of the analog image signals to obtain a plurality of digital image signals at each sampling-and-holding timing and outputting the digital image signals;
- performing phase regulation of each sampling-and-holding timing based on corresponding digital image signals to obtain phase-regulated sampling-and-holding timing;
- and
- performing image processing on the digital image signals obtained at an optimal phase-regulated sampling-and-holding timing, wherein
- the generating includes generating the analog image signal at each phase-regulated sampling-and-holding timing,
- the image reading method further comprising:
- calculating an n-th mean value of the digital image signals at an n-th sampling-and-holding timing, an (n−1)-th mean value of the digital image signals at an (n−1)-th sampling-and-holding timing, and an (n+1)-th mean value of the digital image signals at an (n+1)-th sampling-and-holding timing,
- calculating a first difference between the n-th mean value and the (n−1)-th mean value, and a second difference between the n-th mean value and the (n+1)-th mean value,
- calculating a sum of the first difference and the second difference to obtain a sum of differences at the n-th sampling-and-holding timing, and
- repeating calculating the sum of differences at each sampling-and-holding timing,
- wherein the performing the phase regulating selects a sampling-and-holding timing at which the sum of differences is minimum as the optimal sampling-and-holding timing.
11 more elements
Dependencies are inferred from the claim text.