Facsimile and static presentation processing – Natural color facsimile – Color separation
Reexamination Certificate
1997-11-21
2001-02-20
Lee, Thomas D. (Department: 2724)
Facsimile and static presentation processing
Natural color facsimile
Color separation
C358S461000
Reexamination Certificate
active
06191873
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image reading device, an image reading apparatus, and a method therefor and, more particularly, to an image reading device used in an image scanner or facsimile apparatus for reading light from an original, an image reading apparatus, and a method therefor.
2. Description of Related Art
As an image reading apparatus used in an image scanner or facsimile apparatus, an apparatus using a reduction optical system shown in
FIG. 21
is known. Referring to
FIG. 21
, light is irradiated from a light source
5
to an original
6
. The light reflected by the original
6
is deflected through 90° by a mirror
4
and focused on a CCD image sensor
1
through a lens
2
, thereby converting the light into an image signal. A correction plate (shading correction plate)
3
for correcting a power of cos
4
of a white output waveform lens. The image signal output from the CCD image sensor
1
is A/D-converted into digital data by an analog-to-digital (A/D) converter incorporated in an IC (not shown). The digital data is subjected to an image process. An inexpensive xenon (Xe) lamp or LED is often used as a light source for this image reading apparatus.
A printer serving as an image reading apparatus is available in which a scanner unit is mounted in place of a print head unit including an ink tank detachably mounted in the printer.
The above techniques pose the following problems. Since the absolute light amount of the Xe lamp or LED used in the image reading apparatus is small, a charge accumulation time (to be simply referred to also as an accumulation time hereinafter) in reading operation in the CCD image sensor
1
must be prolonged, and the sensitivity of a reception system must be improved in order to obtain stable image information. The sensitivity characteristics of the light-receiving portion for photoelectrically converting light reflected by the original have limitations although high-speed driving of a CCD device serving as a light-receiving element has advanced. In order to obtain a sufficiently high S/N ratio, the original must be illuminated in a sufficiently large light amount.
For this purpose, to increase the light amount by increasing a drive current to the LED, the drive current changes due to the wavelength of emission light upon heating of the LED itself and a change in forward voltage. As a result, a stable emission intensity cannot be obtained.
In a printer incorporated in a notebook personal computer, when a scanner unit is mounted in place of a print head unit, the scanner unit must be made compact and simple because the printer of this personal computer is compact. In addition, a reduction in power consumption is desired in consideration of driving the notebook personal computer using a secondary battery.
To correctly set the dynamic range in reading an image, a white reference value and an offset value must be measured for each scanner unit because the respective scanner units vary in characteristics. However, in mounting a scanner unit in the built-in printer of the notebook personal computer, white reference setting for setting the white reference value and the offset value is often omitted due to downsizing and low cost. In this case, every time the white reference value and the offset value are to be set, a user must feed originals for measuring the white reference value and the offset value to allow them to read these values, and must set the white reference value and the offset value.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems, and has as its object to provide an image reading device capable of reading a high-quality image under the conditions as a compact, simple arrangement and low power consumption, an image reading apparatus using this image reading device, and a method therefor.
To achieve the above object, a preferred embodiment of the present invention discloses an image reading apparatus for reading an image of original, the apparatus comprising photoelectric conversion means for converting light from the original into an image signal, first correction means for correcting a white level of the image signal, storage means for storing white reference data for white level correction in correspondence with a reference temperature, detection means for detecting a temperature near the photoelectric conversion means, and second correction means for correcting the reference white data on the basis of a temperature difference between the temperature detected by the detection means and the reference temperature, wherein the white level is corrected by the first correction means using the white reference data corrected by the second correction means.
Also disclosed is an image reading device detachably attached to an image processing apparatus having storage means for storing white reference data for white level correction in correspondence with a reference temperature, detection means for detecting a temperature near the photoelectric conversion means, and first correction means for correcting the white reference data on the basis of a temperature difference between the temperature detected by the detection means and the reference temperature, the device comprising photoelectric conversion means for converting light from the original into an image signal, and second correction means for correcting a white level of the image signal, wherein the white level is corrected by the second correction means using the white reference data corrected by the first correction means.
It is another object of the present invention to provide an image reading device capable of preventing a read image from being degraded by causes such as a positional error in mounting a light source and the like under the conditions as the compact, simple arrangement and low power consumption, an image reading apparatus using this image reading device, and a method therefor.
To achieve the above object, a preferred embodiment of the present invention discloses an image reading apparatus for reading an image of original, the apparatus comprising photoelectric conversion means for converting light from the original into an image signal, amplification means for amplifying the image signal, detection means for detecting a peak level of an image signal corresponding to a pixel within an effective pixel range of the photoelectric conversion means and a peak level of an image signal corresponding to a pixel outside the effective pixel range on the basis of an image signal for a white reference obtained from the photoelectric conversion means, and setting means for comparing the peak levels detected by the detection means and setting an amplification factor of the amplification means on the basis of the comparison result.
It is still another object of the present invention to provide a reading unit capable of stably reading a high-quality image even if the reading unit is mounted in place of a print head unit, an image reading apparatus in which this reading unit is mounted, control of this image reading apparatus, and a control method therefor.
To achieve the above object, a preferred embodiment of the present invention discloses an image reading method for reading an image of original by using an image reading device having photoelectric conversion means for converting light from the original into an image signal and amplification means for amplifying the image signal, the method comprising the steps of detecting a peak level of an image signal corresponding to a pixel within an effective pixel range of the photoelectric conversion means and a peak level of an image signal corresponding to a pixel outside the effective pixel range on the basis of an image signal for a white reference obtained from the image reading device, comparing the detected peak levels, and setting an amplification factor of the amplification means on the basis of the comparison result.
It is still another object of the present invention to provide a reading unit capable of reading a high-quali
Fukunaga Koji
Katano Kiyoshi
Kobayashi Makoto
Maeda Kenji
Mizoguchi Shigeru
Brinich Stephen
Canon Kabushiki Kaisha
Lee Thomas D.
Morgan & Finnegan , LLP
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