JP2793223B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that forms an image using a multi-head.

[Prior Art] This type of recording head has variations in output characteristics due to constituent materials, manufacturing processes and the like. Therefore, if the recording head is used as it is, density unevenness occurs in the output image. In particular, when a color image is formed using a multi-recording head, color unevenness is caused, which is more serious. Therefore, the present applicant has proposed an image forming apparatus that corrects input image data with correction data corresponding to the output characteristics of a recording head and prevents density unevenness.

Incidentally, the actual density unevenness and color unevenness slightly change due to the use environment of the recording head, aging, and the like. Even in this case, if the original correction state (correction amount) of the recording head can be easily grasped, the cause of the density unevenness and the color unevenness (weak point or the like) can be quickly investigated, and appropriate measures can be taken in many cases.

[Problems to be Solved by the Invention] However, conventionally, the correction state of the recording head cannot be easily grasped. For this reason, it was more difficult to find the cause of the color unevenness.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, and it is an object of the present invention to provide an image forming apparatus capable of easily ascertaining a recording head correction state.

[Means for Solving the Problems] In order to achieve the above object, an image forming apparatus according to the present invention provides an image forming apparatus, comprising: a plurality of recording elements constituting a multi head for color image formation; Correction means for correcting the recording conditions of each of the recording elements in order to reduce variations in characteristics; manual input means for manually inputting a change in the correction state of the correction means; and displaying the correction state of the correction means for each forming color Display means for displaying the correction state changed by the manual input means.

Further, an image forming apparatus according to the present application is an image forming apparatus that forms an image using a recording head, and performs correction according to each recording density characteristic of the recording head in order to reduce variation in recording density characteristics of the recording head. Storage means for storing data, correction means for correcting input image data in accordance with the correction data stored in the storage means, and display for graphically displaying the correction data stored in the storage means in response to a first manual instruction Means.

[Description of Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a sectional view of the digital color copying machine of the embodiment. This device is roughly divided into two parts. 1
One is a color image scanner unit 1 (hereinafter, referred to as a scanner unit) for reading a color document image, and the other is a printer unit 3 (for example, Japanese Patent Application Laid-Open 54-5993
No. 6). The scanner unit 1 and the printer unit 3 can be separated, and can be installed at a remote place by extending the connection cable.

The scanner unit 1 includes an exposure lamp 14, a lens 15, and an image sensor 16 (for example, a CCD sensor) capable of reading a line image in full color. Reads the large-size sheet document image sent by 12. The controller unit 2 performs various image processing on the digital color image data read by the scanner, and has a processing function such as an interface with the printer unit 3. Operation unit 10
Is connected to the controller unit 2 so that various kinds of information for operating the copying apparatus can be input to the controller unit 2.
As a result, the controller unit 2 issues various instructions regarding the operations of the scanner unit 1 and the printer unit 3 according to the operation input information. When performing complicated image editing processing,
By attaching a digitizer or the like instead of 11 and connecting it to the controller unit 2, advanced image processing becomes possible.

In the printer section 3, the recording paper is fed by a paper feed cassette 20 for storing cut paper of a small fixed size (in this embodiment, A4 to A3 size) or a large size (A2 in this embodiment).
(Up to A1 size). Paper can be fed from the outside of the apparatus (manual paper feeding) by feeding recording paper one by one from the manual feed slot 22 along the paper feed unit cover 21. The pick-up roller 24 picks up cut sheets one by one from the sheet feed cassette 20, and the picked-up cut sheet is conveyed to the first sheet feed roller 26 by the cut sheet feed roller 25.
In the case of the roll paper 29, it is sent out by a roll paper feed roller 30, cut into a fixed length by a cutter 31, and transported to a first paper feed roller 26. The recording paper inserted from the manual feed slot 22 is conveyed to the first paper feed roller 26 by the manual feed roller 32. These pick-up rollers 24, cut paper feed rollers 25, roll paper feed rollers 30, and first feed rollers 2
6, and the manual feed roller 32 are driven by an unillustrated paper feed motor (a DC servo motor is used in the present embodiment), and on / off control is performed as needed by an electromagnetic clutch attached to each roller. When the printer operation is started in accordance with an instruction from the controller unit 2, the recording paper selected and fed by any of the above-described paper feeding paths is transported to the first paper feeding roller 26. At this time, after forming a predetermined amount of paper loop to remove the skew of the recording paper, the first paper feeding roller 26 is turned on to convey the recording paper to the second paper feeding roller 27. When printing, use a scanning carriage with a recording head 37, etc.
The scanning motor 35 reciprocates the carriage 34 on the carriage rail 36. In this forward scan, an image is printed on the recording paper, and in the backward scan, an operation of feeding the recording paper by a predetermined amount by the paper feed roller 28 is performed. The recording paper printed in this way is discharged to the discharge tray 23 to complete the printing operation.

FIG. 6 is a diagram showing details around the scanning carriage 34. As shown in FIG. In the figure, a paper feed motor 40 is a driving source for intermittently feeding recording paper, and drives a second paper feed roller 27 via a paper feed roller 28 and a second paper feed roller clutch 43. The scanning motor 35 is a driving source for scanning the scanning carriage 34 in the direction of arrow A or B via the scanning belt 42. In this embodiment, a pulse motor is used for the paper feed motor 40 and the scan motor 35 because accurate paper feed control and carriage scanning control are required.

When the recording paper reaches the second paper feed roller 27, the second paper feed roller clutch 43 and the paper feed motor 40 are turned on, and the recording paper is conveyed on 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, and this sensor information is used for paper position control, jam control, and the like. When the recording paper reaches the paper feed roller 28, the paper feed second roller clutch 43 and the paper feed motor 40 are turned off, and a suction operation is performed from the inside of the platen 39 by a suction motor (not shown) to bring the recording paper into close contact with the platen 39. Let it.

Scan carriage 34 prior to the image recording operation on recording paper
Is moved to the position of the home position sensor 41, and then a forward scan is performed in the direction of arrow A, and cyan, magenta, yellow, and black inks are ejected from a predetermined position from the recording head 37 to record an image. In this embodiment, the recording head 37 is an ink jet nozzle of a type in which bubbles are formed by heat and ink droplets are discharged at the pressure, and four nozzles each having 256 nozzles are used. . When the image recording for the predetermined length is completed, the scanning carriage 34 is stopped,
The backward scanning is started in the direction indicated by the arrow B, and the scanning carriage 34 is started.
Is returned to the position of the home position sensor 41. Further, during this backward scanning, the paper feed for the line length recorded by the recording head 37 is performed in the direction of arrow C by driving the paper feed roller 28 by the paper feed motor 40. When the scanning carriage 34 stops at the home position detected by the home position sensor 41, a recovery operation of the recording head 37 is performed. This is a process for performing a stable printing operation, and in order to prevent unevenness at the start of ejection due to a change in viscosity of ink remaining in the nozzles of the printing head 37, the feeding time, the internal temperature of the apparatus, and the like. ,
This is a process of performing a pressurizing operation on the recording head 37, an idle discharge operation of the ink, and the like according to pre-programmed conditions such as a discharge time. By repeating the above operation, image recording is performed on the entire surface of the recording paper.

FIG. 7 is a diagram showing details of the scanner mechanism. In the figure, a CCD unit 18 is a unit composed of a CCD 16, a lens 15, and the like, and is provided with a main scanning motor 50 fixed on the rail 54, a pulley 51, a pulley 52, and a main scanning direction driving system including a wire 53. Move on the platen glass
The image on 17 is read in the main scanning direction. The light-shielding plate 55 and the home position sensor 56 are used for position control when the CCD unit 18 is moved to the main scanning home position in the correction area 68 shown in the figure. The rail 54 is mounted on rails 65 and 69, and has a sub-scanning motor 60, pulleys 76, 67, 68, 71,
It is moved by a sub-scanning direction drive system including shafts 72 and 73 and wires 66 and 70. The light-shielding plate 57 and the home position sensors 58 and 59 connect the rail 54 to the home position of each sub-scan in the book mode for reading a document such as a book placed on the platen glass 17 or in the sheet mode for reading a sheet. Used for position control when moving. The sheet feed motor 61, the sheet feed rollers 74 and 75, the pulleys 62 and 64, and the wire 63 are mechanisms for feeding a sheet document. This mechanism is located on the platen glass 17, and feeds a sheet original placed downward by a predetermined amount by sheet feed rollers 74 and 75.

FIG. 8 is an explanatory diagram of the reading operation in the book mode and the sheet mode. In the book mode, the correction area
Book mode home position in 68 (book mode H
Move the CCD unit 18 to P) and from here place the platen glass 17
The reading operation of the entire surface of the original placed on the is started. Prior to document scanning, the CCD unit 18 is positioned in the correction area 68 to set data necessary for processing such as shading correction, black level correction, and color correction. Then, the main scanning motor
The scanning in the main scanning direction (the direction of the arrow in the figure) is started by 50. When the reading operation of the area is completed, the main scanning motor 50 is rotated in the reverse direction and the sub-scanning motor 60 is driven to move the CCD unit 18 to the correction area 68 of the area. Subsequently, in the same manner as described above, processing such as shading correction, black level correction, and color correction is performed as necessary.
Perform an area reading operation. By repeating the above scanning, the reading operation of the entire surface from the area is performed, and after the reading operation of the area is completed, the CCD unit 18 is returned to the book mode home position again. In the present embodiment, the platen glass 17 can read a document of the maximum A2 size, and in fact, it must scan a large number of times if it is held.However, in this description, the operation is simplified for easy understanding. ing.

In the sheet mode, the CCD unit 18 is moved to the sheet mode home position (sheet mode HP), and the area of the sheet document is repeatedly read while the sheet feed motor 61 is operated intermittently to read the entire sheet document. Prior to scanning the original, shading correction is performed in the correction area 68,
After performing processes such as black level correction and color correction, the main scanning motor 50 starts scanning in the main scanning direction (the direction of the arrow in the figure). When the reading operation on the outward path of the area is completed, the main scanning motor 50 is rotated in the reverse direction, and the sheet feed motor 61 is driven during the backward scanning to move the sheet document by a predetermined amount in the sub-scanning direction. Then repeat the same operation,
Scans the entire sheet document.

Assuming that the above-described reading operation is the same-size reading operation, the area that can be read by the CCD unit 18 is actually a large area as shown in FIG. This is because the digital color copying apparatus of this embodiment has a built-in magnification / reduction scaling function. That is, assuming that the area recordable by the recording head 37 is fixed to 256 dots at a time, for example, when a 50% reduction operation is performed, at least a double of 512
This is because image information of a dot area is required. Therefore, the scanner unit 1 has a function of reading and outputting image information of an arbitrary image area by one main scanning reading.

FIG. 9 is a functional block diagram of the digital color copying apparatus of the embodiment. In FIG. 1, control units 102, 111, and 121 are control circuits for controlling the scanner unit 1, the controller unit 2, and the printer unit 3, respectively, and include a microcomputer, a program ROM, a data memory, a communication circuit, and the like. The control units 102 to 111 and the control units 111 to 121 are connected by a communication line.
A so-called master-slave control mode in which 2,121 perform operations is adopted.

When operating as a color copying apparatus, the control unit 111 operates according to input instructions from the operation unit 10 and the digitizer 114. The digitizer 114 is for inputting position information necessary for trimming, masking processing and the like, and is connected as an option when complicated editing processing is required.

The control unit 102 controls the mechanical drive unit 105 that controls the driving of the mechanism of the scanner unit 1 described above, and controls the exposure control unit 103 that controls the exposure of the lamp when reading a reflected original. The control unit 102 also controls the analog signal processing unit 100 and the input image processing unit 101 that perform various types of processing related to images.

The control unit 121 controls the mechanical drive unit 122 that controls the mechanism of the printer unit 3 described above, absorbs the time variation of the mechanical operation of the printer unit 3, and corrects the delay due to the arrangement of the recording heads 117 to 120 on the mechanism. Of the synchronous delay memory 115 for performing the control.

 Next, the operation will be described along the flow of image data.

The image formed on the CCD 16 is converted into an analog electric signal by the CCD 16. The converted image information is serially processed in the order of red (R) → green (G) → blue (B) and input to the analog signal processing unit 100. The analog signal processing unit 100 performs analog-to-digital conversion (A / D conversion) after performing sample-and-hold, dark level correction, dynamic range control, etc. for each color of red, green, and blue, In the embodiment, the digital image signal is converted into a digital image signal of each color (8 bits long) and output to the input image processing unit 101. The input image processing unit 101 similarly performs necessary correction processing in the reading system such as CCD correction and γ correction as a serial multi-valued digital image signal.

The image processing unit 107 performs smoothing processing, edge enhancement, black extraction, masking processing for correcting the color of the recording ink used in the recording heads 117 to 120, and the like. The serial multi-valued digital image signal output is input to the binarization processing unit 108. The binarization processing unit 108 is a circuit for binarizing a serial multi-valued digital image signal, and can select simple binary with a fixed slice level, pseudo halftone processing with a dither method, or the like. Here, the serial multi-valued digital image signal is converted into a 4-color binary parallel image signal.

The synchronous delay memory 115 absorbs time variations in the mechanical operation of the printer unit 3 and performs delay correction based on the arrangement of the recording heads 117 to 120 on the mechanism. For this purpose the recording head 11 internally
The timing required for driving 7 to 120 is also generated. The head driver 116 is an analog drive circuit for driving the recording heads 117 to 120, and internally generates a signal capable of directly driving the recording heads 117 to 120. Recording heads 117-120 are
Cyan (C), magenta (M), yellow (Y),
The black (K) ink is ejected to record an image on a recording sheet.

FIG. 10 is an explanatory diagram of the timing of the image between the circuit blocks of FIG. In the figure, a signal BVE is a signal indicating an image effective section for each scan in the main scanning reading operation described with reference to FIG. By outputting the signal BVE a plurality of times, image output of the entire screen is performed. The signal VE is a signal indicating an effective section of an image of each line read by the CCD 16. The signal VE also becomes valid when the signal BVE is valid. Signal V
CK is a clock signal for sending out the image data VD. The signals BVE and VE change in synchronization with the signal VCK. signal
HS is a signal used when the signal VE is output in one line, and is valid when the valid and invalid sections are repeated discontinuously.
If the signal is valid continuously during line output, it is an unnecessary signal. This signal indicates the start of image output of one line.

FIG. 11 is a diagram for explaining signal processing in the image processing unit 107. In the figure, image data (hereinafter referred to as input image data) serially input to an image processing unit 107 is sent to a serial / parallel conversion unit 201, where parallel signals of Y (yellow), M (magenta), and C (cyan) are output. , And then sent to the masking unit 202. Masking part 2
Reference numeral 02 denotes a circuit for correcting the color smear of the output ink, and performs an operation such as the following equation.

Here, Y, M, C: input data Y ', M', C ': output data The nine coefficients are determined by a masking control signal from the control unit 200. After the masking unit 202 corrects the ink smear, it is input to the selector unit 203 and the UCR unit 205 as a serial signal.

The selector 203 has input image data and a masking unit 202.
The output image data is input. Selector 203
Usually, the input image data is selected by the selector control signal (1) sent from the control unit 200. When the color correction in the input system is not performed sufficiently, the control signal (1)
Selects the image data output from the masking unit 202,
Is output. The serial image data output from the selector 203 is input to the black extraction unit 204. The black extraction unit 204 detects the minimum value of Y, M, C in order to use the minimum value of Y, M, C in one pixel as black data. The detected black data is input to the UCR unit 205.

The UCR unit 205 subtracts black data extracted from each of the Y, M, and C signals. For black data, a coefficient is simply multiplied. The black data input to the UCR unit 205 is corrected for time lag with respect to the image data sent from the masking unit 202, and then the following equation is calculated.

Y ′ = Y−a ₁ Bk M ′ = M−a ₂ Bk C ′ = Ca− ₃ Bk Bk ′ = a ₄ Bk where, Y to Bk: UCR part input data Y ′ to Bk ′: UCR part output Data The coefficients (a ₁ , a ₂ , a ₃ , a ₄ ) are the UCs sent from the control unit 200
Determined by the R control signal.

The data output from the UCR unit 205 is then input to the γ offset unit 206. In the γ offset section 206, the following tone correction is performed.

Y ′ = b ₁ (Y−C ₁ ) M ′ = b ₂ (M−C ₂ ) C ′ = b ₃ (C−C ₃ ) Bk ′ = b ₄ (Bk−C ₄ ) where Y to Bk : Γ offset part input data Y ′ to Bk ′: γ offset part output data The coefficients (b _{1 to} b ₄ and C _{1 to} C ₄ ) are determined by the γ offset control signal sent from the control unit 200.

The signal whose gradation has been corrected by the γ offset section 206 is
The image data is input to a line buffer 207 for storing image data for the lines. In the line buffer 207, five lines of data necessary for the subsequent-stage smoothing / edge enhancement unit 208 are output in five lines in parallel according to a memory control signal sent from the control unit 200. The signals for the five lines are input to a filter having a variable filter size in accordance with a filter control signal from the control unit 200, and are subjected to smoothing and then edge enhancement.

The image data output from the smoothing / edge enhancement unit 208 is input to the color conversion unit 209, and color conversion is performed by a color conversion control signal from the control unit 200. For example, the color to be converted, the color to be converted, and the area in which the signal is valid are input in advance by the digitizer device 114 in FIG. 9, and the color conversion unit 209 replaces the image data based on the data. . In this embodiment, a detailed description of the color conversion unit 209 is omitted. The image signal output from the smoothing / edge enhancement unit 208 and the image signal of the color conversion unit 209 are input to the selector 210,
The image data to be output is selected by the selector control signal (2). Which image data is selected is determined by designating an effective area input from the digitizer 114. The image signal selected by the selector 210 is input to the binarization processing unit 108 in FIG.

The head correction unit 211 will be described with reference to FIG.

FIG. 1 is a detailed block diagram of the head correction unit 211 of FIG. In the figure, 265 to 268 are characteristic ROMs, and C, M,
Original density unevenness correction data corresponding to each of the 256 nozzles provided in the Y and Bk recording heads is written. Such density unevenness correction data is written, for example, at a factory.

Reference numeral 271 denotes a working RAM. First, all the correction data of C, M, Y, and Bk are transferred from the characteristic ROMs 265 to 268 or a back-up RAM 272 described later, and if necessary, the correction data is changed. Stores the correction data to be transferred to the selection RAM 260 as the correction data actually used
RAM. Reference numeral 272 denotes a backup RAM, and the stored contents are always retained by the battery 273 even when the power is turned off. The contents of the work RAM 271 are backed up by instructions.
Stored in RAM272.

On the other hand, from VDin, digital image data is C,
Enter in the order of M, Y, K. Therefore, CPU258
Input image data VDin from 265 to 268 (or working RAM 271)
C, M, Y, K, and the like, density non-uniformity correction data is taken out in the order in which they are combined, and this is sequentially written into the selection RAM 260. Reference numeral 263 denotes a bidirectional buffer, which is used when writing density unevenness correction data extracted from the characteristic ROMs 265 to 268 into the selection RAM 260.

Reference numeral 250 denotes an address counter, which generates an address of a correction amount selection table RAM 260 (hereinafter, referred to as a selection RAM) described later. In this embodiment, the head of 256 nozzles corresponds to four colors, and is a 10-bit counter that counts a value corresponding to a total of 1024 nozzles. Counter 250 is controlled by signals HS and VE.

The selector 259 is provided for the lower 10 bits of the address of the 16-bit address bus output from the CPU 258 or the counter 25.
Selects any of the 0 10-bit outputs. The selector 259 is used when writing correction data to the selection RAM 260.
When the address output 8 is selected and the correction data is read from the selection RAM 260, the output of the counter 250 is selected.

The correction data output from the selection RAM 260 together with the input of the image data VDin is input to an address terminal of a correction table ROM (hereinafter, referred to as a correction ROM) 262 through the flip-flop 252 together with the image data VDin. In the correction ROM 262, correction tables as shown by characteristics 1 to 5 in FIG. 12 are written in advance. FIG. 12 shows five types of correction tables, but there are many more actual correction tables, for example,
There are 30 ways. The table written in the correction ROM 262 is written so as to output the correction amount data ΔA (= correction data × VDin) corresponding to the input A (= correction data and VDin). That is, when the image data VDin is input (horizontal axis) in FIG. 12, any one of the characteristics 1 to 5 is selected by the input correction data (for example,%) at that time. The correction data Δ thus read from the correction ROM 262
A is once latched to the flip-flop 254 and the adder 256
Is added to the input image data VDin, and is output via the flip-flop 257 as corrected data (VDin + ΔA).

2 and 3 relate to a diagram for explaining an operation of changing correction data according to the embodiment. FIG. 2 is a display screen when an instruction to change correction data is given by a key (not shown) on the operation unit 10.
This screen is displayed on a liquid crystal touch panel (not shown) on the operation unit 10. In FIG. 2, reference numeral 209 denotes a full display of the correction data, in which the correction data at the present time for the designated color is graphically displayed by dots as shown in the drawing in correspondence with the nozzles of the recording head. Reference numeral 210 denotes a cursor display, which indicates correction data (head nozzle) to be changed.
Reference numeral 207 denotes a left key (←), and the cursor 210 moves to the left side of the screen. Reference numeral 206 denotes a right key (→) for moving the cursor 210 to the right side of the screen. Operator key 2
The correction data of the portion to be changed is designated by 06,207. Reference numeral 205 denotes a color key (CLR). When the key 205 is pressed, the color for which correction data is to be displayed can be changed. Reference numeral 204 denotes a currently designated color symbol display. Each time the color key 205 is pressed, the color is changed in the order of cyan (C), magenta (M), yellow (Y), and black (K). Reference numeral 203 denotes a reset key (RST).
The correction data of M265 to 268 is transferred to RAMs 271 and 272.
As a result, the current correction data display becomes the original correction data display.

Reference numeral 202 denotes a screen switching key (A). When the key 202 is pressed, the display is alternately switched between all data display in FIG. 2 and partial enlarged display in FIG. 3 described later. The screen switching key 202 is the third
In the case of the partially enlarged display of the figure, it is displayed normally, but in the case of the whole data display of FIG. 2, the display is reversed.

FIG. 3 is a view showing a partially enlarged display screen of the correction data. In the figure, reference numeral 211 denotes a partially enlarged display of the correction data 209, and four data before and after the correction data indicated by the cursor 210 are enlarged and displayed. Column 212 is cursor 2
Numeral 10 indicates an address display (or a nozzle number may be used) of the correction data specified, and a column 213 indicates a numerical display (for example, hexadecimal display) of the correction data. Reference numeral 200 denotes an up key (↑). When the key 200 is pressed, the content of the correction data pointed by the cursor 210 increases by a predetermined amount. Reference numeral 201 denotes a down key (↓). When the key 201 is pressed, the content of the correction data decreases by a predetermined amount. Of course, these keys
200 and 201 may be used on the screen of FIG. In this way, the necessary change of the correction data is performed while switching the screen. 208
Is an exit (EXT) key. When the key 208 is pressed, the display / change mode of the correction data is ended.

FIG. 4 is a control flowchart of the CPU for a correction data changing operation. In step S300, the screen shown in FIG. 2 is displayed. In step S301, the cursor 210 is displayed.
In step S302, a key input from the operation unit 10 is waited, and if there is a key input, a process corresponding to the key input is performed. That is, when the up / down keys 200 and 201 are pressed, the process proceeds to step S303, where the up / down processing of the correction data is performed. When the screen switching key 202 is pressed, the flow advances to step S304 to alternately switch the entire screen and the partially enlarged screen. When the reset key 203 is pressed, the process proceeds to step S305, where the original correction data is read from the characteristic ROM corresponding to the designated color, set in the corresponding portions of the work RAM 271 and the backup RAM 272, and displayed again. When the color key 205 is pressed, the flow advances to step S306 to change the color designation and to display the correction data and the color again. When the left / right keys 206/207 are pressed, the flow advances to step S307 to move the cursor 210 left / right. When the end key 208 is pressed, the process is terminated and the screen is returned to a normal screen (not shown).

In the above embodiment, the correction data is changed for each nozzle. However, the present invention is not limited to this. For example, in consideration of the resolution of the human eye, it may be better to change the density in a certain range. Also, the trouble of the change operation can be saved.
Therefore, for example, in partial enlarged display, graphic display may be performed with an average value of several data units, and a change operation may be performed to increase or decrease the average value.

Further, when the partially enlarged screen after the change is returned to the all data display screen, the number data of the part may be displayed in a state of being dispersed by an individual difference from the average value of the increased or decreased part.

Further, when the correction data of a certain nozzle is up / down, several nozzles before and after the correction data are also up / down with a certain width (for example, weighted in inverse proportion to the distance from the nozzle). good. In this way, the correction data draws a smooth curve, and an extreme change can be prevented.

Further, in the above-described embodiment, the operation of changing the correction data is performed by the judgment of the operator, but the present invention is not limited to this. For example,
Several types of correction data groups (or change algorithms) may be prepared in consideration of changes in output characteristics due to changes in the use environment, changes over time, and the like, and the operator may select and apply one of them. The several kinds of correction data are collected together with various load tests, aging tests, and the like in, for example, an apparatus manufacturing factory, and are statistically processed. In this way, even an operator who is unfamiliar with the analysis of the density change can easily correct the density.

Further, for example, an image capture memory for one image information is added, and on the other hand, a test pattern image in which density unevenness is easily determined is printed, and the printed test pattern image is read from a scanner unit and the image information is stored in the added memory. The correction data may be automatically changed by storing and comparing this image information with the image information of the test pattern image.

In the above embodiment, the recording head of the ink jet system is used, but the invention is not limited to this. The present invention can be applied to other wire dot systems, electrostatic printing systems, thermal transfer systems, and the like.

In the above-described embodiment, the screen shown in FIG. 2 is set to each color, but is not limited to this. If simultaneous display of a plurality of colors is performed, visual comparison of graphic display becomes easy, and the cause of color unevenness is easily grasped.

In the above-described embodiment, the image data given to each recording element is corrected when the recording condition of the recording element is corrected. However, the present invention is not limited to this. For example, a method of changing the power energy applied to each recording element may be used. In the case of using an ink jet system in which ink is ejected using air pressure and electrostatic force as a multi-head, for example, it is possible to change the printing conditions of each print element by correcting the air pressure and / or electrostatic force described above. Good. As described above, the correction method can be variously modified according to the recording method of the image forming head.

[Effects of the Invention] As described above, according to the present invention, in order to reduce the variation in the recording density characteristics of each of a plurality of recording elements, when correcting the recording conditions of each of the recording elements, it is necessary to correct the recording conditions for each of the recording elements. Since the change of the correction state can be manually input based on the displayed correction state, the manual change of the correction state for each forming color is facilitated.

Further, since the correction data for reducing the variation of the recording density characteristics of the recording head stored in the storage means in response to the manual instruction is displayed in a graph, the degree of correction of the recording density by the recording head is shown. Can be visually and easily understood by the user and the operator.

[Brief description of the drawings]

FIG. 1 is a detailed block diagram of the head correction unit 211 in FIG. 11, FIGS. 2 and 3 are diagrams for explaining an operation of changing correction data in the embodiment, and FIG. FIG. 5 is a cross-sectional view of the digital color copying apparatus of the embodiment, FIG. 6 is a view showing details around the scanning carriage 34, FIG. 7 is a view showing details of the scanner mechanism, and FIG. FIG. 9 is a functional block diagram of the digital color copying apparatus of the embodiment, FIG. 9 is an explanatory diagram of the image timing between the circuit blocks of FIG. 9, and FIG. FIG. 12 is a diagram for explaining signal processing in the image processing unit 107, and FIG. 12 is a diagram illustrating characteristics of a correction table according to the embodiment. In the figure, 250: counter, 260: correction amount selection table RA
M, 265-268 …… Characteristic ROM, 263 …… Bidirectional buffer, 259
… Selector, 252, 254, 255, 257… Flip flop, 262… Correction table ROM, 271… Working RAM, 272
… Backup RAM, 273… battery, 256… adder.

Continuation of the front page (56) References JP-A-61-142427 (JP, A) JP-A-62-229426 (JP, A) JP-A-62-184526 (JP, A) JP-A-63-28667 (JP) , A) JP-A-63-196932 (JP, A) JP-A-2-47065 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/385 B41J 2/045 B41J 2/21

Claims (5)

(57) [Claims] A correcting means for correcting printing conditions of each of the plurality of printing elements constituting the multi-head for forming a color image in order to reduce variations in printing density characteristics of the printing elements; and a correction state of the correcting means. Image forming means for manually inputting the change of the image, and display means for displaying the correction state of the correction means for each forming color and displaying the correction state changed by the manual input means. apparatus. 2. The image forming apparatus according to claim 1, wherein the correction unit corrects image data given to each of the plurality of recording elements as the recording condition. 3. An image forming apparatus for forming an image by using a recording head, wherein the memory stores correction data corresponding to each recording density characteristic of the recording head in order to reduce variations in recording density characteristics of the recording head. Means, correction means for correcting input image data according to correction data stored in the storage means, and display means for displaying correction data stored in the storage means in a graph in response to a first manual instruction. An image forming apparatus comprising: 4. The image forming apparatus according to claim 3, wherein said display means enlarges and displays a part of said graph display in response to a second manual instruction. 5. A printing apparatus according to claim 3, further comprising a recording head corresponding to the number of colors, wherein said display means displays a graph of correction data of the recording head corresponding to a color corresponding to a third manual instruction. Image forming apparatus.