Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-09-22
2003-08-12
Lee, Cheukfan (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S406000, C358S474000
Reexamination Certificate
active
06606172
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an image information processing apparatus and an image information processing method for processing electric signals from a four-channel output CCD, which receives optical image information from, e.g. a document, and outputs electric signals, and to an image forming apparatus such as an electronic copying machine for forming images, which includes this image formation processing apparatus.
BACKGROUND ART
Recently, image forming apparatuses such as digital copying machines have been widely used more and more. An increasing number of such digital copying machines have used CCDs capable of high-resolution reading and laser optical units realizing image-quality enhancing processing and high-resolution laser driving.
Besides, there is a demand for high-speed digital copying machines which replace high-speed analog copying machines, and there is a need for devices for realizing higher-speed, higher-resolution processing.
As one type of such devices, CCDs capable of realizing high-speed, high-resolution processing have been developed and begun to be put on the market as products.
Such high-speed CCDs have already been used as four-channel output CCDs for achieving high-speed operations, and pre-processing systems using such four-channel output CCDs have been proposed.
Compared to pre-processing systems using conventional two-channel output CCDs, pre-processing systems using high-speed four-channel output CCDs are constructed such that right and left data of output signals from the CCD are output simultaneously and a left-side even component OS
2
, a left-side odd component OS
1
, a right-side even component OS
4
and a right-side odd component OS
3
are processed through the same signal transmission path (processing path).
In a signal amplification processing AMP in the pre-processing system, left-side and right-side even components and odd components are signal-amplified, synthesized and AD-conversion (ADC)-processed. The resultant image signals are input to a high-speed scanner control ASIC in the form of 1 pixle/8 bit digital signals with two channels of even component DOBx and odd components DOAx.
The two-channel signals of even components DOBx and odd components DOAx input to the high-speed scanner control ASIC are processed as four-channel signals in order to decrease a processing speed with bus-width conversion and to perform a shading correction for correcting a density gradient deviation occurring in each pixel of image data with respect to image density.
Thereafter, shading-corrected image data is bit inverted, and the order of the image data is rectified by raster-conversion. Then, in order to change the internal high processing speed to a low transfer speed, the image data is transferred in units of four pixels to an image processing ASIC.
In the image processing ASIC, the image data is converted to image data of one pixel unit. Then, the image data is subjected to a series of system correction processes by image processing such as filtering processing, range correction processing, magnification conversion (enlargement, reduction) processing, density conversion processing and gray-scale processing.
As regards comparison in signal output construction of the CCDs, in the case of the conventional two-channel output CCD, if the order of output image signals for one line of the CCD is considered, these two outputs are delivered in the state in which the even components and odd components are arranged from the left-end pixel signal (proper order for image processing). On the other hand, in the case of the present high-speed CCD, i.e. four-channel output CCD, if the order of output image signals for one line of the CCD is considered, the four-channel outputs are delivered such that the left-side outputs of both even components and odd components are delivered in order from the left-end pixel signal to the central image signal at last, and the right-side outputs are delivered in order from the right-end pixel signal to the central pixel signal at last. Thus, the signals are not well arranged (improper order for image processing).
As stated above, the four-channel output CCD is used dividedly for left and right components and odd and even components in the main scan direction. In the case of the conventional two-channel output CCD, a variance in characteristics of transfer paths after shading for odd and even components can be suppressed and corrected to a problem-free level through subsequent image processing using a low-pass filter (LPF) or error diffusion processing. In the case of the four-channel output CCD, however, a variance in left-and-right CCD sensitivity characteristics appears on image data after shading correction processing. Such a variance cannot be suppressed and corrected by the conventional image processing alone. To cope with this, a correction circuit is provided for left and right image data before image processing.
The correction circuit for left and right image data is necessary since sensor characteristics differ between the left and right in the main scan direction due to the pre-processing system configuration using the four-channel output CCD to achieve high-speed operation. However, no technique has been made clear for adjusting the correction methods in the left and right correction circuits. It should be noted, however, that unless correction for the left and right is made, a variance in CCD characteristics differs between the left and right due to a difference in CCD devices, and a difference among devices increases with respect to image density reproduction.
As has been described above, where the four-channel CCD is used to achieve high-speed operation, the correction circuit is required since the sensor characteristics differ between the left and right in the main scan direction due to the pre-processing system configuration. However, adjustment for the correction method of the left and right correction circuit has not yet been clear. Unless correction for the left and right is made, a variance in CCD characteristics differs between the left and right due to a difference in CCD devices, and a difference among devices increases with respect to image density reproduction.
DISCLOSURE OF INVENTION
The object of the present invention is to provide an image information processing apparatus, an image information processing method and an image forming apparatus, wherein when a four-channel output CCD is used, a left and right correction circuit in which adjustment for correction is made clear is used for correction, whereby a variance in CDD characteristics of the left and right due to a difference in CCD devices is eliminated and a stable image density free of a density error between the left and right devices can be reproduced.
The present invention provides an image information processing apparatus for performing an information process on information read by a four-channel output CCD, the apparatus comprising: accumulation means for receiving optical image information and accumulating photoelectrically converted electric signals in a one-line element; a four-channel output CCD having an output section for outputting the electric signals accumulated in the accumulation means from a first end portion of the one-line element at even intervals, an output section for outputting the electric signals accumulated in the accumulation means from the first end portion of the one-line element at odd intervals, an output section for outputting the electric signals accumulated in the accumulation means from a second end portion of the one-line element at even intervals, and an output section for outputting the electric signals accumulated in the accumulation means from the second end portion of the one-line element at even intervals; correction amount determination means for comparing the electric signals from the first end portion, received from the four-channel output CCD, and the electric signals from the second end portion, detecting a deviation, and determining a correction amount on the basis of the deviation;
Foley & Lardner
Kabushiki Kaisha Toshiba
Lee Cheukfan
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