JPH03199060A - Image-forming apparatus - Google Patents

Abstract

PURPOSE:To correct the unevenness of density by means of a simple constitution by discriminating a character region from image data and by thinning data other than the character region out of the image data converted into a binary on the basis of discrimination results. CONSTITUTION:A manuscript is read by a color CCD16, A/D converted by an analog signal processor 100, and inputted to an input image processor 101. The input image processor 101 conducts necessary corrective processing, and inputs the manuscript to an image processor 103 and character region discriminator 102. The image processor 103 conducts smoothing process, edge emphasis, black extraction, masking process for color correction of recording ink used in recording heads 108-111, etc. The output of serial continuous-tone image signal from the image processor 103 is inputted to a binary processor 104. The character region discriminator 102 determines whether the relevant region is a character region or not, and outputs its determination signal. When an image signal coming out of the binary processor 104 is inputted to an uneven density-correcting part 105, the image signal is thinned outside of the character region. When the character region is thinned, blank parts are made in that region and a printed part is high in density and the unevenness is also difficult to be conspicuous so that no correction of unevenness is conducted in the region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus that forms images using a multi-head or the like.

[Prior Art] Conventionally, as an example of this type of device, there is a device that converts a read image into a digital signal, performs data processing, and then forms an image using a multi-head. Characteristic variations due to the manufacturing process,
There has been a problem in that density unevenness occurs in the output image due to variations in characteristics of the multi-head constituent materials. Therefore, based on the storage means for storing data corresponding to the output characteristics of each head of the multi-head array, and this storage data,
The present applicant has also proposed an apparatus that is provided with means for correcting input image data and uses both of these means to prevent the above-mentioned density unevenness.

[Problems to be Solved by the Invention] However, in the conventional example described above, since the correction means is applied to a read image signal composed of multiple bits, it is necessary to provide a memory for storing correction information and a complicated circuit. Must be.

An object of the present invention is to provide an image forming apparatus that solves the above problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a binarization means for binarizing image data, a discrimination means for discriminating a character area from the image data, and a discrimination result of the discrimination means. and means for converting data other than the character area out of the image data binarized by the binarizing means based on the binarization means.

[Function] According to the present invention, density unevenness correction is performed with a simpler configuration by spreading the binarized image data.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an internal configuration diagram of a color image forming apparatus embodying the present invention.

The original is read by the color CC016 through the lens 15 and input to the analog signal processing section 100 as an electrical signal. The analog signal processing unit 100 performs sample/hold, dark level correction, dynamic range control, etc. for each color on the serially input image information of red → green → blue, and then performs analog-to-digital conversion (A/D conversion). ), and converts it into a serial multivalued (8 bits long for each color in this embodiment) digital image signal and inputs it to the input image processing unit 101.

The input image processing unit 101 similarly performs correction processing necessary in the reading system, such as COD correction and γ correction, on the input signal as it is as a serial multi-valued digital image signal. The output signal of the input image processing section 101 is input to the image processing section 103 and the character area determination section 102.

The image processing unit 103 performs smoothing processing, edge enhancement, black extraction, masking processing for color correction of recording inks used in the recording heads 108 to 111, etc. on the input signal. The serial multivalued image signal output from the image processing section 103 is input to the binarization processing section 104 .

The character area determination unit 102 stores an image of a bone in a certain minute area, determines whether or not the area is a character area based on the difference between the minimum value and maximum value and the density of the area, and outputs a determination signal. do.

The binarization processing unit 104 is a circuit for binarizing the input serial multi-level digital image signal, and performs the binarization by selecting simple binary processing using a fixed slice level, pseudo intermediate processing using a dither method, etc. I can do it. Here, the serial multi-value digital signal is converted into a four-color binary parallel image signal.

Switching between simple binary and dither in the binarization processing unit 104 is controlled by the scanner control unit 120.
It is also possible to automatically switch based on the determination result of the character area determination unit 102.

The image signal output from the binarization processing section 104 is sent to the density unevenness correction section 1.
05. The configuration of the density unevenness correction unit 105 will be described later, but in order to make density unevenness less noticeable, the image signal is sluggish in areas other than text areas. Since the character area becomes white when it is dazzling, and the printed area has a high density, the unevenness is not noticeable, so no unevenness correction is performed.

The image signal output from the density unevenness correction section 105 is input to a synchronous delay memory 106 in order to perform delay correction due to the mechanical arrangement of the recording heads 108 to 111.

The head driver 107 is an analog drive circuit for driving the recording heads 108 to 111, and is an analog drive circuit for driving the recording heads 108 to 111.
A signal that can directly drive 8 to 111 is generated internally.

The recording heads 108 to 111 eject cyan, yellow, magenta, and black ink, respectively, to record an image on recording paper.

Note that the scanner control unit 120 has each component 100°10
1, 102.103.104.105.121, and the printer control opening section 121 controls the synchronization delay memory 106.

FIG. 2 shows a detailed configuration diagram of the image processing section 103 and the binarization processing section 104, and will be described.

The input image signal is sent to the serial-parallel converter 201
So, Y (yellow) and 9M (magenta).

After converting it into a C (cyan) parallel signal, it is sent to the masking section 202. The masking unit 202 performs matrix calculations using coefficients given by the control unit 200 (scanner control unit 120) in order to correct color cloudiness of the output ink.

The black extractor 204, which receives the output signal of the serial-parallel converter 201, detects the minimum values of Y, M, and C in order to use the minimum values of Y, M, and C in one pixel as black data. The detected black data is then input to the UCR section.

The OCR section 205 multiplies and subtracts the black data extracted from each of the Y, M, and C signals by a coefficient given by the control section 200, and further multiplies the black data by a coefficient to obtain Y, M, and C signals. M, C, and Bk (black) image information is input to the γ/offset unit 206.

The γ/offset unit 206 performs gradation density correction on the input signal using a coefficient given by the control unit 200.

The image signal outputted from the γ offset unit 206 is transferred to the line buffer 2 which stores N947 worth of image data.
07 is input. This line buffer 207 inputs 5 lines of data necessary for the subsequent smoothing/edge emphasizing section 208 to the emphasizing section 208 in 5 lines in parallel according to a memory control signal given from the control section 200 . In the emphasizing section 208, the signals for five lines are inputted to a spatial filter whose filter size is variable according to a filter control signal from the control section 200, smoothed, and then edge emphasized.

The image data output from the smoothing/edge enhancement section 208 is input to a color conversion section 209, where color conversion is performed in accordance with a color conversion control signal from the control section 200. The image data before and after color conversion are selected by a selector 210 and input to a dither circuit 212.

The dither circuit 212 determines whether to binarize the input signal using a dither matrix or to simply binarize the input signal. is obtained from the dither control signal.

FIG. 3 is an internal configuration diagram of the color image forming apparatus of this embodiment.

The operating unit IO is an operating unit for the operator to obtain a desired copy.

First, the exposure lamp 14. Lens 15. Image sensor 16 capable of reading line images in full color
(in this embodiment, a color CCD with 256 pixels) reads the original image placed on the original table glass and the sheet original image produced by the sheet feeding mechanism 12. Next, various image processing is performed by the scanner section 1 and the controller section 2, and the printer section 3
to record on recording paper.

The recording paper consists of a paper feed cassette 20 that stores cut sheets of small standard sizes (A4 to A3 sizes in this embodiment) and roll paper for recording large sizes (A2 to A3 sizes in this embodiment). Supplied from 29.

The big up roller 24 is a roller for feeding cut sheets one by one from the paper feed cassette 20, and the fed cut sheets are conveyed to the 10th feed roller 26 by the cut paper feed roller 25. be done.

The roll paper 29 is sent out by a roll paper feed roller 30, cut into a standard length by a cutter 31, and then transferred to the paper feed number 10.
- It is conveyed to La 26.

Similarly, the recording paper inserted from the manual feed slot is conveyed to the paper feed roller 26 by the manual feed roller 32.

Big Up Lola 24. Cut paper feed roller 25
．． Roll paper feed roller 30. The paper feed roller 26 and the manual feed roller 32 are connected to a paper feed motor (not shown in the drawings, D
It is driven by a C servo motor (using a C servo motor), and can be turned on and off at any time by electromagnetic clutches attached to each roller.

When the printing operation is started in accordance with an instruction from the controller section 2, recording paper selectively fed from one of the above-mentioned paper feeding paths is conveyed to the paper feeding path 26. In order to eliminate the skew of the recording paper, after creating a predetermined amount of paper loops, the 10th paper feeder 26 is turned on and the recording paper is conveyed to the 20th paper feeder 27.

When printing with the recording head 37, the recording head 3
A scanning carriage 34 on which a device 7 or the like is attached performs reciprocating scanning on a carriage rail 36 by a scanning motor 35. Then, in the forward scan, an image is printed on the recording paper, and in the backward scan, the paper feed roller 28 performs an operation to feed the recording paper by a predetermined amount.

The printed recording paper is discharged to the paper discharge tray 23, and the printing operation is completed.

Next, the scanning carriage 3 and the invention will be described in detail using FIG.

The paper feed motor 40 is a drive source for intermittently feeding the recording paper, and the paper feed motor 40 is a driving source for intermittently feeding the recording paper. The paper feeder 20th-ra 27 is driven via the paper feeder 20th-ra clutch 43.

The scanning motor 35 moves the scanning carriage 34 to the scanning belt 34.
This is a drive source for scanning in the directions of arrows A and B. In this embodiment, since accurate paper feed control is required, the paper feed motor 40. A pulse motor is used as the scanning motor 35.

When the recording paper reaches paper feed number 20-27, paper feed number 20
-La clutch 431 turns on the paper feed motor 40 and conveys the recording paper over the platen 39 to the paper feed roller 28.

The recording paper is detected by a paper detection sensor 44 provided on the platen 39.
The sensor information is used for position control, jam control, etc.

When the recording paper reaches the paper feed roller 28, the paper feed number 20-
The paper clutch 439 turns off the paper feed motor 40, and a suction operation (not shown) is performed from inside the platen 39 to bring the recording paper into close contact with the platen 39.

Prior to the image recording operation on the recording paper, the scanning carriage 34 is moved to the position of the home position sensor 4I,
Next, forward scanning is performed in the direction of arrow A, and cyan, magenta, yellow, and black inks are ejected from the recording head 37 from predetermined positions to record an image. After recording the image for a predetermined length, the scanning carriage 34 is stopped, and conversely, backward scanning is started in the direction of arrow B, and the scanning carriage 34 is returned to the position of the home position sensor 41.

During the backward scan, the paper is fed by the length recorded by the recording head 37 in the direction of arrow C by driving the paper feed roller 28 by the paper feed motor 40.

In this embodiment, the recording head 37 is an ink jet nozzle that uses heat to form air bubbles and uses the resulting pressure to eject ink droplets, and uses four ink jet nozzles with 256 nozzles each assembled. ing.

Scanning carriage 34 is home position sensor 41
When it stops at the home position detected by , the recording head 37 performs a recovery operation. This is a process for stable printing operation, and in order to prevent unevenness at the start of ejection caused by changes in the viscosity of the ink remaining in the nozzles of the print head 37, paper feeding time, internal temperature of the device, etc. This is a process in which pressure is applied to the recording head 37, ink is idly ejected, etc. according to preprogrammed conditions such as ejection time and the like.

By repeating the operations described above, an image is recorded on the entire surface of the recording paper.

FIG. 5 shows details of the density unevenness correction section 105 of this embodiment, and will be described.

Although this circuit has been explained for one color, it is the same circuit for four colors (C, M, Y, Bk).

Comparison circuit 501 compares the count value of image counter 500, which counts the input binary image signal line by line, with the output value from random number table 505, 506, and if they match, outputs a match signal. The input binary image signal is mixed and outputted by a gate circuit 503 which inhibits image output based on a coincidence signal outputted from a comparison circuit 501.

The signals before and after the gate circuit 503 are input to the selector 505 .

Another selector 504 selects either the character area determination signal output from the character area determination unit 102 or the corrected 0N10FF signal output from the control unit 200 using a selector signal from the control unit 200. and selector 50
The selector 505 selects the gate circuit 503 according to the output signal of 4.
Select either the signal before (no correction) or after (after correction). Normally, the selector 504 outputs a character area determination signal, and based on this signal, the selector 505 does not correct the character area (outputs the signal before the gate circuit 503), but corrects areas other than the literature area and selects the output of the gate circuit 503. do)
, to make unevenness less noticeable.

The random number tables 505 and 506 are tables configured by a RAM in which numbers of pixels to be dazzled are set.
The table is written. The reason why random numbers are used is to perform density correction uniformly and to prevent streaks and the like from occurring due to scattering.

There are two tables (505, 50
6) Yes. In the random number table, the number of nozzles for one color is 256, and 64 values can be written because it is necessary to make a correction of 25% empirically. or,
This machine can correct unevenness by 2mII using an operation unit (not shown)!
Since the operator can specify the percentage of dizziness in units, the microcomputer in the control unit 200 can
The number of pixels that will be dazzled is calculated using a random number generation program, which determines the number of pixels that will be dazzled, and is set in a table.

[Other Embodiments] In the above embodiment, a character area determination circuit is provided to automatically determine the character area so that the image quality of the character area in the input image is not degraded. It is also possible to specify the character area, and in that case, a character area determination circuit is not required. In addition, in this embodiment, the specified correction is always performed, but since the unevenness may or may not be noticeable depending on the density of the image, , which can be connected to the line buffer before edge enhancement), and select whether or not to perform correction depending on the output signal, the correction will be more accurate.

Also, if correction is performed in conjunction with image density detection,
It is easy to add image information (ink ink) to areas with low density.

Furthermore, in the embodiment described above, the microcomputer in the control unit 200 performs random number calculations, but the random number generation circuit and
A comparator configuration is also possible.

In the embodiment described above, the operator uses the operation unit to specify which part and what percentage of unevenness to correct for unevenness, but the printer has a built-in pattern generate function, Print the pattern and use the CCD to read the original
It is also possible to read the data, calculate the unevenness, and automatically correct the unevenness, or create a similar device, create a data ROM for correction there, and install it in the image forming apparatus. You can.

Also, if you have a synchronous delay memory like the above example,
Correction can also be made by performing calculations using a microcomputer or the like and rewriting the image information when the regional bone data in the memory is input.

[Effects of the Invention] As explained above, according to the present invention, higher quality images can be obtained with a simple configuration.

[Brief explanation of drawings]

Fig. 1 is an internal configuration diagram of a color image forming apparatus embodying the present invention, Fig. 2 is a detailed circuit diagram of an image processing section, Fig. 3 is a sectional view of a color image forming apparatus embodying the present invention, and Fig. 4 5 is an explanatory diagram of the operation of the multi-head section of the printer section, and FIG. 5 is a detailed circuit diagram of the density unevenness correction section. 1... Original reading section (scanner), 2... Controller section, 3... Printer section.

Claims (1)

[Claims] 1) A binarizing means for binarizing image data, a discriminating means for discriminating a character area from the image data, and a method for determining the image data binarized by the binarizing means based on the discrimination result of the discriminating means. An image forming apparatus characterized by comprising means for distributing data other than character areas.