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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus, an image forming method, and an image processing method of the image forming apparatus which carry out printing by applying an image processing to original image data obtained from a
scanner or the like.
2. Description of the Related Art
In these years, some types of color digital copying machines have automatic color select functions (ACS).
Jpn. Pat. Appln. KOKAI Publication No. 2002-165101, for instance, discloses an image forming apparatus having a color determination section that determines whether an original scanned by a color CCD sensor is a black-and-white one or a color
one, and a setting section that sets a black-and-white/color mode for image formation on the basis of the determination. In the prior-art techniques including this one, the black-and-white/color determination can be made by the ACS. However, it is not
possible to subject a black-and-white character original and a black-and-white photo original to different processes. As regards a photo original, a gray-scale process is important for the image quality. However, a gray-scale process is not important
for the image quality in the case of a character original.
In a character original, productivity can be improved by applying velocity priority processing which does not place importance on a gray-scale process.
In addition, with respect to an image data printing operation in which the above processing is applied, in an engine having a mechanism in which full color printing is effected in a four-rotation system, if monochromatic printing is effected by a
color printing operation only, a wasteful operation is made, and a printing velocity is slow.
Therefore, there is a need for an image forming apparatus and method and an image processing method of such an apparatus in which restriction of image quality degradation can be made compatible with improvement of productivity by selecting an
image processing section from a plurality of image processing sections for following a user instruction or carrying out automatic determination of an original type, thereby carrying out image processing according to the original type.
BRIEF SUMMARY OF THE INVENTION
According to an aspect of the present invention, there is provided an image forming apparatus comprising: an image reading section having a plurality of sensors with their different features; an image processing section which applies a processing
to image data according to the sensors with their different features, the image data being acquired by the image reading section; at least one of an operating section which accepts a mode specification and a determination section which determines an
original type; and a control section which selects a processing of the image processing section based on the specification of the operating section or the determination of the determination section.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention
may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given
below, serve to explain the principles of the invention.
FIG. 1 is a schematic cross section of an image forming apparatus according to an embodiment of the present invention;
FIG. 2 is a control block diagram depicting a control panel section;
FIG. 3 is a control block diagram depicting a scanner section;
FIG. 4 is a control block diagram depicting a printer section;
FIG. 5 is a control block diagram depicting a basic processing section;
FIG. 6 is a diagram conceptually showing a parameter section which stores a parameter for use in an image processing;
FIG. 7 is a diagram showing a schematic configuration of a monochromatic CCD sensor and a color CCD sensor;
FIG. 8 is a diagram showing a schematic configuration of a four-line sensor;
FIG. 9 is a diagram showing a configuration of an image processing according to a first embodiment of the present invention;
FIG. 10 is a histogram showing density and frequency of a color original;
FIG. 11 is a histogram showing density and frequency of a monochromatic text original;
FIG. 12 is a histogram showing density and frequency of a monochromatic photo original;
FIG. 13 is a flow chart showing an example of an image processing according to the first embodiment;
FIG. 14 is a flow chart showing an example of an image processing according to a second embodiment of the present invention;
FIG. 15 is a diagram showing a configuration of an image processing according to a third embodiment of the present invention;
FIG. 16 is a flow chart showing an example of an image processing according to the third embodiment;
FIG. 17 is a flow chart showing an example of an image processing according to a fourth embodiment of the present invention;
FIG. 18 is a view showing a configuration of an image processing according to a fifth embodiment of the present invention;
FIG. 19 is a flow chart showing an example of an image processing according to the fifth embodiment;
FIG. 20 is a view showing a configuration of an image processing according to a sixth embodiment of the present invention; and
FIG. 21 is a flow chart showing an example of an image processing according to the sixth embodiment.
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will now be described with reference to the accompanying drawings. In the embodiment, this invention is applied to a color digital copying machine 1.
FIRST EMBODIMENT
A schematic internal structure of a color digital copying machine 1 will be described with reference to accompanying drawings. The color digital copying machine 1 houses a scanner section 2, a printer section 3, and a paper feeding section 4 in
a casing. The scanner section 2 irradiates an original set at an original table (not shown), guides reflection light from the original to a light receiving element via a plurality of optical members, carries out photoelectric conversion, and outputs
image data. The printer section 3 outputs an image on paper P based on image data read from the original at the scanner section 2, or image data inputted from an external device (not shown). The paper feeding section 4 supplies the paper P to the
printer section 3.
In addition, a double-side unit 5 and a manual insertion unit 6 are removably mounted at the right side in the figure of the casing of the color digital copying machine 1. The double-side unit 5 inverts the paper P having an image formed on one
side thereof at the printer section 3, and supplies the paper to the printer section 3 again. The manual insertion unit 6 supplies the paper P to the printer section 3 by means of manual insertion.
The printer section 3 has a photosensitive drum 11 having a tube shaft which extends in a front-rear direction (in a paper surface direction) of the color digital copying machine 1. At the periphery of the photosensitive drum 11, a charger
device 12, an exposure device 13, a black developer 14, a revolver 15, an intermediate transfer belt 16, and a drum cleaner 18 are provided along a rotation direction indicated by the arrow in the figure, of the photosensitive drum 11.
The charger device 12 charges the outer periphery surface of the photosensitive drum 11 at a predetermined potential. The exposure device 13 exposes the drum surface charged at the predetermined potential, and forms an electrostatic latent image
based on image data.
The black developers 14 are disposed in opposite to each other between the photosensitive drum 11 and the exposure device 13. The black developer 14 supplies and develops a black developing agent to an electrostatic black image formed on the
drum surface by means of the exposure device 13, develops an image, and forms a black developing image on the drum surface. The black developer 14 has a mixer which supplies the developing agent by stirring it and developing rollers disposed on the drum
surface in opposite to each other via a predetermined developing gap. The black developer 14 is movably provided so as to make the developing roller proximal to or distant from the drum surface. Also in the black developer, the developing agent is
supplied from a toner cartridge.
The revolver 15 is rotatably provided in adjacent to the left side in the figure of the photosensitive drum 11. The revolver 15 has a yellow developer 15Y, a magenta developer 15M, and a cyan developer 15C each having a structure basically
identical to that of the black developer 14. Each of these developers is removably housed in the revolver 15 along the rotation direction of the revolver 15. In addition, these developers have toner cartridges 15y, 15m, and 15c which house the
developing agents of the respective colors. Then, the color developers are selectively disposed in opposite to each other on the drum surface from the side of the photosensitive drum 11 by rotating the revolver 15 in counterclockwise direction.
An intermediate transfer belt 16 is disposed at an adjacent position upwardly in a gravity direction with respect to the photosensitive drum 11. The intermediate transfer belt 16 is provided in a tensile manner by being around a drive roller
16a, a transfer front roller 16b, and a transfer opposite roller 16c, and a tension roller 16d, each of which has a rotary shaft extending in the front-rear direction. The drive roller 16a is fixedly provided with respect to the casing upward of the
revolver 15; the transfer front roller 16b is fixedly provided with respect to the casing upwardly of the photosensitive drum 11; and the transfer opposite roller 16c is fixedly provided at a position to be rolled in contact with a longitudinal transfer
passage described later. The tension roller 16d is biased from the inside to the outside of the belt so as to impart a predetermined tensile force to the intermediate transfer belt.
Moreover, at the inside of the intermediate transfer belt 16, there is provided a primary transfer roller 17 for causing the intermediate transfer belt 16 to be rolled in contact with the drum surface and for transferring to the intermediate
transfer belt 16 the developing agent image formed on the drum surface. The primary transfer roller 17 is biased in the direction of the photosensitive drum 11 so as to pressurize the intermediate transfer belt 16 on the drum surface by a predetermined
pressure.
At the periphery of the intermediate transfer belt 16, a belt cleaner 25 and a secondary transfer roller 19 are provided such that they can be made proximal to or distant from the belt surface, respectively. The belt cleaner 25 is provided on
the outer periphery of the drive roller 16a via the intermediate transfer belt 16 upwardly of the revolver 15. The secondary transfer roller 19 is provided at a position which sandwiches a longitudinal transport passage described later between the
roller 19 and the transfer opposite roller 16c via the intermediate transfer belt 16. The drum cleaner 18 is disposed in contact with the photosensitive drum 11 from the right side in the figure.
The paper feeding section 4 has two paper feeding cassettes 4a and 4b to be overlapped at the top and bottom. Pickup rollers 20 which pick up paper P at the upper-most end housed in the cassettes are provided respectively at the right upper end
in the figure, of the paper feeding cassettes 4a and 4b. A feed roller 21 and a separation roller 22 are disposed to be connected to each other at the adjacent positions on the downstream side in the paper pickup direction by the pickup roller 20.
In addition, a longitudinal transport passage extending upwardly in a substantially vertical direction through a secondary transfer region in which the above described intermediate transfer belt 16 and secondary transfer roller 19 are rolled in
contact with each other is provided at the adjacent position at the right side in the figure, of the paper feeding cassettes 4a and 4b. On the longitudinal transport passage, a fixing section 23 which fixes the developing agent image transferred on
paper P by heating and pressurizing the agent is provided. The fixing section 23 has a heating roller 23a which incorporates a heater therein and a pressurization roller 23b disposed to be pressurized against the heating roller 23a.
Now, an image forming operation by the color digital copying machine 1 will be described here.
First, a color printing operation for forming a color image will be described below. In an initial operation, the black developer 14 is moved downwardly and is spaced from the drum surface; the revolver 15 is revolved in a clockwise direction;
and a yellow developer 15Y is opposed on the drum surface. Also, the revolver is revolved axially in a counterclockwise direction, and is spaced from the intermediate transfer belt 16. Then, the secondary transfer roller 19 is moved in the right
direction in the figure spaced from a longitudinal transport passage, and is spaced from the intermediate transfer belt 16.
Then, image data is read from an original (not shown) via the scanner section 2, or image data is inputted from an external device (not shown). Further, the photosensitive drum 11 is rotated in a clockwise direction, and the drum surface is
charged uniformly at a predetermined potential by means of the charger device 12. At this time, the intermediate transfer belt 16 as well is rotated in a counterclockwise direction.
Further, based on image data for color decomposed yellow, the exposure device 13 operates, and a yellow electrostatic latent image is formed on the drum surface. Then, a yellow developing agent is supplied to the electrostatic latent image on
the drum surface via the yellow developer; the yellow electrostatic latent image is developed; and a yellow developing agent image is formed on the drum surface. The yellow developing agent thus formed on the drum surface is moved by rotation of the
photosensitive drum 11, and a primary transfer region rolled in contact with the intermediate transfer belt 16 is passed.
At this time, a bias of inverted polarity against the potential of the yellow developing agent image is imparted via the primary transfer roller 17, and the yellow developing agent image on the drum surface is transferred onto the intermediate
transfer belt 16.
After the yellow developing agent image has been transferred onto the intermediate transfer belt 16, the yellow developing agent remaining on the drum surface without being transferred is removed by the drum cleaner 18. At this time, the
residual charge on the drum surface as well is removed at the same time.
Then, for the preparation for forming a next magenta electrostatic latent image on the drum surface, the drum surface is charged uniformly by means of the charger device 12; the revolver 15 is revolved; and the magenta developer 15M is opposed to
the drum surface.
In this state, a series of processes described above, i.e., exposure, developing, and transfer to the intermediate transfer belt are effected in order, and the magenta developing agent is transferred to be overlapped with the yellow developing
agent image on the intermediate transfer belt 16. After the magenta developing agent image has been thus transferred, the cyan developing agent is transferred to be overlapped in the same manner.
Then, in any of the developers, the revolver 15 is revolved at a home position which is not opposite to the drum surface. Instead, the black developer 14 is risen, and is opposed to the drum surface. In this state, processes similar to the
above described processes are executed, and the black developing agent image is transferred onto the intermediate transfer belt 16 to be overlapped with the yellow developing agent image, magenta developing agent image, and cyan developing agent image.
When the developing agent images of all colors have been thus overlapped on the intermediate transfer belt 16, the secondary transfer roller 19 is moved in the left direction in the figure, and is rolled in contact with the intermediate transfer
belt 16. Then, the belt cleaner 25 as well is brought into contact with the intermediate transfer belt 16. In this state, the developing agent images of all the colors overlapped on the intermediate transfer belt 16 are moved by rotation of the
intermediate transfer belt 16, and the secondary transfer region between the belt and the secondary transfer roller 19 is passed.
At this time, the paper P picked up from the paper feeding cassette 4a, for example, by the pickup roller 20, is transported upwardly of the longitudinal transport passage, and is fed to the secondary transfer region.
Then, a bias of inverted polarity against the potential of the developing agent image of each color is applied via the secondary transfer roller 19, and the developing agent image of each color on the is intermediate transfer belt 16 is
transferred onto the paper P. After the developing agent image has been transferred onto the paper P, the developing agent which remains on the intermediate transfer belt 16 is removed by means of the belt cleaner 25.
The paper P on which the developing agent images of all the colors color has been collectively transferred is then heated and pressurized after the fixing section 23 has been passed; the developing agent image of each color is fixed onto the
paper P, and a color image is formed. The paper P on which a color image has been thus formed is ejected onto a paper ejection tray 24 provided at the downstream side of the fixing section 23.
In a color printing operation for forming a color image in this manner, the photosensitive drum 11 makes three rotations in order to form a developing agent image by supplying the developing agents of the yellow, cyan, and magenta colors housed
in the revolver 15. Further, when a developing agent image is formed by a black developing agent, the photosensitive drum 11 makes one rotation. That is, the foregoing color printing operation is an operation which forms an image by repeating an
operation for supplying a developing agent four times (a plurality of times).
In the case of a color digital copying machine for forming a color image by three colors, cyan, magenta, and yellow, an operation for supplying a developing agent is carried out three times (a plurality of times). The thus constructed copying
machine is effective if an attempt is made to increase a printing velocity because the number of operations is reduced.
Now, a monochromatic operation for forming a monochromatic image will be described here. In an initial operation, in any of the yellow developer 15Y, magenta developer 15M, and cyan developer 15C, the revolver 15 is positioned at a home position
which is not opposed to the surface of the photosensitive drum 11. In addition, the black developer 14 is disposed so as to be opposed to the surface of the photosensitive drum 11.
Then, an operation for forming a black image described with respect to a color printing operation is carried out, and a black developing agent image is formed on the paper P.
In this manner, in a monochromatic operation, a photosensitive drum makes one rotation in order to form a developing agent image by supplying a black developing agent. That is, the foregoing monochromatic operation is an operation which forms an
image by making one operation for supplying a developing image agent.
A control configuration of the color digital copying machine 1 will be described with reference to FIG. 2 to FIG. 5. FIG. 2 is a diagram showing a control configuration of a control panel section 7; FIG. 3 is a diagram showing a control
configuration of the scanner section 2; FIG. 4 is a diagram showing a control configuration of the printer section 3; and FIG. 5 is a diagram showing a control configuration of a basic processing section 8, respectively.
As shown in FIG. 2 to FIG. 5, a main CPU (control section) 61, a control panel CPU 31, a scanner CPU 41, and a printer CPU 51 control the basic processing section 8, the control panel section 7, the scanner section 2, and the printer section 3,
respectively.
The main CPU 61 communicates with the control panel CPU 31, scanner CPU 41 and printer CPU 51 and controls the same.
The control panel CPU 31 is connected to a ROM 32 and a RAM 33. Based on data stored in the ROM 32 and RAM 33, the control panel CPU 31, for example, detects operations of switches on the control panel 34, turns on/off LEDs on the control panel
34, and controls a display and a touch panel on the control panel 34.
A user sets a mode when a control panel 34 is operated, thereby making a copy. Mode settings include an image mode setting and an original mode setting, for example. In an image mode, "full color", "black", and "automatic original
determination" are provided. A full color mode is provided as a mode for making a copy in full color irrespective of original type. A black mode is provided as a mode for making a copy in white and black irrespective of original type. An automatic
original determination mode is provided as a mode for automatically determining an original color, a monochrome text, or monochromatic photograph, and then, carrying out full color printing for a color original, monochromatic printing for a monochromatic
text, and monochromatic multiple-value printing for a monochromatic photograph. In addition, "automatic color determination" may be provided instead of "automatic original determination". An automatic color determination mode is provided as a mode for
carrying out printing in color printing operation if a color original is set and for carrying out printing in a monochromatic operation if a monochromatic original is set. Then, the user sets an image mode, and sets an original mode. In an original
mode, modes such as "text/photo", "text", and "printed photo" can be set as original type. The text/photo mode is provided as a mode for setting an original on which a text and a printed photograph coexist. The text mode is provided as a mode for
setting an original including only text (or characters and lines). The printed photo mode is provided as a mode for setting processing suitable to a printed photo-graph original to be carried out. Automatic original determination is not limited to
determination of type of the original. For example, an original type may further be determined from a photo, a map, or a color photo printed on photosensitive paper. In determination of an original type, even if determination is not made on page by
page base, a configuration in which determination is made on a predetermined block by block basis may be provided. In addition, the user can set a magnification such as original size expansion or reduction when the user operates the control panel 34,
thereby making a copy.
Based on data stored in a ROM 42 and RAM 43, the scanner CPU 41 controls a mechanism section 44 including a motor, a solenoid, etc. (not shown), and also controls an automatic document feeder (ADF) 45, a coordinate input device (editor) 46, an
analog/digital converter circuit (A/D) 47, a shading correction circuit (SHD) 48 and a line memory 49.
A CCD section 50 is connected to the A/D converter 47.
In this embodiment, the CCD section 50 is designed to read an image by two devices such as a monochromatic CCD sensor 50a and a color CCD sensor 50b, as shown in FIG. 7. However, as shown in FIG. 8, a configuration may be provided such that an
image is read by one device 50c using four line sensors for black (K), red (R), green (G), and blue (B) colors. As the sensors thus provided at the scanner section 2, there are disposed sensors with their differential features. In the features of these
sensors, the resolutions of image reading or image reading velocities may be different as well as different colors. As shown in FIG. 9, the image read by the monochromatic CCD sensor 50a is processed at a monochromatic CCD scan processing section 101,
and the image read by the color CCD sensor 50b is processed at a color CCD scan processing section 102. The image processing of each processing section which is applied to original image data read by these processing sections include conversion
processing from an analog signal into a digital signal, shading correction processing, and gamma correction processing. As the monochromatic CCD sensor 50a which reads an original as a monochromatic image, there may be used a sensor with its excellent
reading velocity and resolution as compared with the color CCD sensor 50bwhich reads an original as a color image.
On the basis of data stored in a ROM 52 and a RAM 53, the printer CPU 51 controls a mechanism section 54 including a motor, a solenoid, etc. (not shown), and also controls a sorter 55, a large cassette feeder (LCF) 56, a laser conversion circuit
57, and a laser drive circuit 58 that controls a semiconductor laser 59.
The printer CPU 51 achieves the color printing operation and monochromatic operation described previously under the control of the main CPU 61 by controlling each section in this manner.
The main CPU 61 controls the entirety of the color digital copying machine 1 according to control programs stored in a ROM 62 and a RAM 63. The ROM 62 stores various parameters to be used at the time of image processing.
As shown in FIG. 6, a parameter section 64 which stores a parameter for use in a variety of image processes is provided at part of a storage region of the ROM 62. At the parameter section 64, there are provided: a filtering processing parameter
section 64a; an discrimination processing parameter 64b; a compression/decompression processing parameter section 65c; a half tone processing parameter section 64d; a background processing parameter section 64e; a range correction processing parameter
section 64f; a density adjustment processing parameter section 64g; a gamma correction processing parameter section 64h; a color conversion processing parameter section 64i; and a black-adding parameter section 64j. At the each parameter section 64,
parameters are provided according to types of the image mode and original mode described above. Also, based on the set image mode and original mode, when the main CPU 61 carries out each image processing, the parameters are set at an image processing
section for selecting the parameters and carrying out processing. In setting of the parameters based on such a configuration, there is no need to provide all the parameters indicated at each of the parameter sections described above. A single parameter
setting may be provided, or a plurality of settings of arbitrarily combined parameters may be provided.
Moreover, at the above filtering processing parameter section 64a, when copying is further made, when expansion or reduction of an original is set in size, parameters for setting a filter coefficient and a filter strength according to its
magnification are stored in plurality. In the settings of filter coefficients and filter strength according to the magnification, a magnification in a predetermined range may be set from a table, i.e., by selecting a set value. In addition, a plurality
of values is stored to be associated with predetermined magnifications, and linear interpolation is provided according to a specified magnification, whereby a calculation result thereof may be set.
A data switch/buffer memory section 65 effects switching as to where data scanned by the scanner section 2 is to be sent, and which data is to be sent to the printer section 3. Details of the structure and operation of an imaging processing
section 66 will be described later. A compression/decompression section 67 compresses/decompresses image data. A page memory 46 stores image data in units of a page. A display memory 69 stores image data to be displayed on a display. A printer
controller 70 develops code data from a personal computer 71 into image data. A display font ROM 72 develops code data onto the display memory 73. A print font ROM 74 develops code data onto the page memory 68. A compression memory 75 stores data
compressed by the compression/decompression section 67.
The main CPU 61 is further connected via an I/F controller 76 to a hard disk drive (HDD) 77, an optical disk drive 78, a facsimile processing section 79, a local area network (LAN) interface (I/F) section 80, and a PC interface (I/F) section 81.
The HDD 77 stores various programs, such as OCR automatic recognition software, for performing character recognition on the basis of the data | | |
