Image reading device and gain setting method in image reading device
AssigneeToshiba Tec Kabushiki Kaisha
InventorSueo Ueno
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Abstract
An image reading device includes a CCD which photoelectrically converts optical information and outputs an image signal in an analog form, a PGA which receives an output from the CCD, amplifies the output with a programmable gain, and outputs the output, an ADC which receives an output from the PGA, A/D-converts the output, and outputs an image signal in a digital form, and a CPU which calculates a gain which makes an output from the ADC match a reference value by using an output from the ADC and the reference value, thereby setting a gain for the PGA. This arrangement makes it possible to set a gain in a short period of time and shorten the first copy time in an image forming apparatus or MFP system using the image reading device of this invention.
Claims8
An image reading device comprising:
- a CCD which photoelectrically converts optical information and outputs an image signal in an analog form;
- a PGA which receives an output from said CCD, amplifies the output with a programmable gain, and outputs the output;
- an ADC which receives an output from said PGA, A/D-converts the output, and outputs an image signal in a digital form;
- and
- a CPU which calculates a gain which makes an output from said ADC match a reference value by using an output from said ADC and the reference value, and setting a gain for said PGA.
A gain setting method in an image reading device, comprising:
- the step of photoelectrically converting optical information and outputting an image signal in an analog form by using a CCD;
- the step of amplifying the image signal by using a PGA which can program a gain;
- the step of A/D-converting the amplified image signal by using an ADC and outputting an image signal in a digital form;
- and
- the step of using a CPU to calculate a gain which makes an output from the ADC match a reference value by using an output from the ADC and the reference value to and set a gain for the PGA.
Dependencies are inferred from the claim text.