JP3374610B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to an image forming apparatus.
To correct the curl that occurs on the paper onto which the toner image has been transferred.
Image formation that corrects and prevents clogging in the machine
Related to the device. [0002] 2. Description of the Related Art Electronic copiers and laser printers
In an electrophotographic image forming apparatus, a toner image
When the paper on which is transferred is passed through the fixing device,
Conveyance path discharged from fixing device to tray due to pressure
Jammed paper in the middle tray in duplex copying
Paper positioning error or transport error to the image forming area
Occurs. [0003] This curl causes the water content of the paper and the toner to be heated.
Caused by shrinkage of the toner due to cooling after
You. In particular, with the recent spread of color copiers,
-In copy, the amount of toner on the paper is larger than in black and white copy.
Paper curl caused by heating / shrinking of the toner
Is not negligible and may be caused by misalignment between color toners.
Color misregistration, resulting in poor image quality and
Copy quality is also reduced due to the rippled used paper.
U. Conventionally, a device for correcting this type of curl
Various types are proposed as (so-called decal device)
Have been. FIG. 16 shows the detection of the curl of the sheet after fixing.
It is an explanatory view of an example of a conventional decal device to correct,
4 is a sheet, 40 is a sheet transport path, 41 and 42 are sheet transport rollers.
, 43 is a curl detector, 44 is a decurler control circuit,
45 is a decurler device, 46 and 47 are pulleys, 48 is a decal
-Label, 49 is a cam roll, S1 and S2 are paper centers.
It is sa. In FIG. 1, a sheet on which a toner image has been transferred
Reference numeral 4 designates a sheet conveying path 40 by sheet conveying rollers 41 and 42.
It is transported in the direction of the arrow. Paper transport rollers 41, 42
Between the curl detector 43 and the front of the curl detector 43
Later, paper sensors S1 and S2 are arranged. Paper transport
The sheet 4 conveyed by the roller 40 is detected by the sheet sensor S1.
The leading edge is detected, and the leading edge is further detected by the paper sensor S1.
At that time, the curl detector 43 determines whether the paper
Detecting that the paper is curled and detecting
Detect size. This detection signal is output to a decurler control circuit 44.
And the decurler control circuit 44 adjusts the size of the curl.
Drives the decurler device 45 accordingly to execute curl correction
I do. FIG. 17 illustrates an example of the decurler device of FIG.
It is a schematic diagram, 46, 47 is a pulley, 48 is a decurler
A belt 49 is a cam roll. This decurler device comprises a pair of pulleys 46,
The upper side of the decarveled 48 stretched over 47
The cam roll 49 is arranged in contact from the side,
-Pass the paper between the label 48 and the cam roll 49
The cam roll 49 according to the size of the curl
The depressed amount of the decal label 48 corresponding to the
The reverse of the curl of the paper due to the nip shape with
To correct the curl by giving [0008] It should be noted that the curl in the opposite direction to that shown in the figure is fixed.
Positively placed the cam roll 49 inside the decal label 48
Or place it on the lower outside and
Make a correction. Other decal devices have other
Some use the nip of a soft roll and a hard roll
Are known. As a disclosure of this kind of prior art,
Is described in, for example, JP-A-5-221574, or
There is JP-A-6-3900. The above conventional technology is paper
The decurling device detects the curl state of the
This is a control method, but the toner to be transferred onto the paper
The curl amount is estimated according to the amount of
In some cases, the control device is controlled. That is, the amount of toner transferred onto the paper is
Integrates the gradation data of the image area and curls the total value.
This determines the amount of correction. [0011] However, the curl of the paper is
It is greatly affected by the amount of toner transferred to the paper. Up
Note that curl correction according to the prior art involves
Is detected and corrected.
The distribution of the amount was considered constant. In particular, the above gradation
In curl correction using the integrated value of data,
For example, an image where the upper half is black and the lower half is pure white, or the right half
Even if the image is pure black and the left half is pure white, its gradation data
Is the same, and the same correction amount is used for an image with a uniform entire surface.
The problem of not being able to properly correct curl
there were. In the case of double-sided copying, the front and back sides are also used.
Curl correction amount is determined by the difference between the total values of the gradation data
The distribution of toner amount on the front and back sides is not the same.
Problem that the curl cannot be properly corrected
Was. An object of the present invention is to solve the above-mentioned problems of the prior art and
By performing curl correction according to the toner distribution on the paper
And a decurling device that always enables proper curl correction
An object of the present invention is to provide an image forming apparatus having the same. [0013] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
In addition, according to the present invention, as shown in FIG.
Image forming means 1 for forming a toner image and transferring it to paper 4
And pressurizing or applying pressure and heating to form the toner image
Fixing means 2 for fixing to paper 4, paper after the fixing process
Image form having decurling means 3 for correcting curl
In the apparatus, the decurling means 3 isPaper transport direction
Deca divided into multiple in the orthogonal direction (lateral direction)
Belt and decal rollAnd the paper 4
In the direction (lateral direction) perpendicular to the paper transport directionplural
An area dividing means 7 for dividing the area into areas;
Integrates each gradation data of the image to be formed
To be integrated by the gray scale integrating means 8
The gradation data of the plurality of areas by using a gradation distribution on the paper.
A gradation distribution data storage means 9 for storing as data;
The gradation distribution data stored in the gradation distribution data storage means 9
Control the curl adjustment amount of the decurling means 3 according to the
And a decal control means 10.
Sign. The configuration of the present invention will be described in more detail.
Then, it is as follows. (1) The area division by the area dividing means 7 is performed on paper.
The image area to be formed is moved in the transport direction of the paper (process
Direction) or a direction perpendicular to the transport direction (lateral direction)
Direction) or process direction and lateral direction
Is adopted. (2) The above-mentioned gradation integrating means 8 calculates all the pixels in the image area.
Grayscale data may be integrated, but consider the processing speed.
By adding the number of pixels above a certain gradation,
It is desirable to adopt a configuration for obtaining gradation distribution data. (3) In the case of double-sided copying, the front side
Means for integrating image gradation data and gradation data for backside image
For integrating the surface image and the gradation data of the integrated surface image
Calculation means for calculating the difference between the gradation data of the image and the back side image
And a curl correction amount is generated from the difference value. sand
FIG. 1 illustrates the basic configuration of an image forming apparatus according to the present invention.
(A) is an overall configuration diagram, (b) is a decal
It is a system configuration diagram of an apparatus. In FIG. 1, reference numeral 1 denotes an image forming means;
Carrier, 1b is charging means, 1c is writing means, 1d is development
Means, 1e is transfer means, 1f is cleaning means, 2 is
Fixing means, 3 decal means, 4 paper, 5 image signal
A laser scanning synchronization means, 7 a region dividing means, 8
Is gradation data integration means, 9 is gradation distribution data storage means,
Reference numeral 10 denotes a decal control unit. In FIG. 1A, the image forming means 1 is charged.
Writing on the surface of image carrier 1a uniformly charged by means 1b
Forming an electrostatic latent image according to the image signal by the
This is developed with toner by the developing means 1d. Place for color images
For example, four colors (black: K, yellow: Y, magenta:
M, Sian: four colors corresponding to the formation of each electrostatic latent image of C)
And superimposed development is performed. Therefore, FIG.
The configuration will be slightly different. The toner image carried on the image carrier 1a is transferred.
Is transferred onto the sheet 4 by the means 1e and
And is fixed on the paper 4 by heating or heating / pressing.
Also, in FIG. 3B, the area dividing means 7 is
The scanning from the laser scanning synchronizing means 6 constituting the stage 1c
Area to be formed on the paper 4 based on the period signal
The process direction, or the lateral direction, or both
Divide into multiple regions in the direction. The gradation data accumulating means 8 receives a signal from the image signal source 5.
Are integrated for each of the above regions. Gradation
The cloth data storage means 9 stores the integrated gradation data for each area.
And the sheet 4 on which the toner image has been transferred is
When reaching the stage 3, it is given to the decurler control means 10 and
The curler amount of the curler device 3 is controlled. In addition, each of the above
The gradation data of the divided region is obtained by calculating the pixel gradation of the entire region of the divided region.
For integration of all tone data or pixels of a specified tone or higher
Instead, the gradation of one or more pixels is subject to integration
It is also possible to use [0020] DESCRIPTION OF THE PREFERRED EMBODIMENTS In the configuration of the present invention described above, an image
The image forming means 1 of the forming apparatus forms an electrostatic latent image corresponding to an image signal.
Develop with toner to form a toner image, which is electrostatically
Alternatively, the image is transferred to the sheet 4 by applying pressure. The fixing means 2 is pressurized
Alternatively, the toner image is formed on the sheet 4 by applying pressure and heat.
Fixed to a permanent image. The decurling unit 3 transfers the toner image.
The curl correction is performed according to the amount of toner on the sheet. Area
The dividing means 7 divides the paper 4 in the process direction or
Either the process direction or the process direction and the lateral direction
To split. The gray scale integrating means 8 is provided for the plurality of areas.
The gradation data of all the pixels to be formed, or
The number of pixels having a predetermined gradation or higher is integrated. The gradation distribution data storage means 9 stores the gradation product
The gradation data of the plurality of regions integrated by the calculating means 8 is
This is stored as gradation distribution data on the recording paper. Decal system
The control means 10 is stored in the gradation distribution data storage means 9.
Of the decurling means 3 according to the obtained gradation distribution data.
Control the amount of adjustment. In the case of double-sided copy, the gradation
A means for integrating the gradation data of the paper surface image into the integrating means 8
Means for integrating the gradation data of the step and the back side image;
Difference between the gradation data of the front image and the gradation data of the back image
It is calculated by the difference calculation means, and curl correction is performed from the difference value.
A positive amount is generated and given to the decal control means 10.
You. [0023] Embodiments of the present invention will be described below with reference to the drawings.
This will be described in detail. FIG. 2 shows the decurler means according to the present invention.
System configuration for explaining a first embodiment of an image forming apparatus provided with
11 is an image processing apparatus, and 12 is a laser scanning apparatus.
Inspection system I / F, 13 is a region division control circuit,
14 is a buffer, 15 is an adder, 16 is a latch circuit, 1
7 is a data bus, 18 is a CPU, 19 is RAM, 20 is
ROM, 21 is an I / O, 22 is a clock generation circuit, 23
Is a decurling control circuit, and 24 is a decurling device. In this embodiment, in one-sided copying,
When decaling by dividing the process direction into multiple areas
Only the configuration for one color (here, K) is shown. Other colors
The same applies to (Y, M, C). In the figure,
Image data D processed by the image processing device 11_VIs a laser
-Laser scanning output from the scanning system I / F12
The data is output to the buffer 14 in synchronization with the synchronization signal L / S.
The image clock signal CL from the image processing device 11_VIs the area
It is given to the division control circuit 13 and
Period signal L / S (line synchronization signal)
The buffer 14 is enabled until the count is reached.
Count enable signal C_EAnd output this count
Enable signal C_EWhile the image data is being output
D_VIs input to the adder 15 through the buffer 14 and
Is calculated. The region division control circuit 13 is a laser
When the scanning synchronization signal L / S is a predetermined count number (a predetermined line)
Buffer 14 is disabled when the number becomes
And the gradation data latch signal C_LOut
Image data (gradation data)
), And the adder 15 resets the count.
Signal C_RIs output to reset the adder 15. Luck
The grayscale data latched by the switch circuit 16 is transmitted to the data bus 17.
Are stored in the RAM 19. This is distributed over the entire area of the sheet 4 (for one page).
It repeats for every predetermined number of lines
Color image is processed in the same way and the gradation data for four colors is integrated.
You. FIG. 3 shows the integration of the gradation data obtained in this embodiment.
FIG. 8 is an explanatory diagram of an example of a value distribution, in which a process is performed from the leading edge of a sheet.
The distribution of the gradation data in the direction
The minimum is at the large and B portions. The fact that the integrated value of the gradation data is large means that
The amount of toner fixed on the paper is large and the integrated value is small
That is, the amount of toner is small. This means that the car
The amount of curl is the largest, and the amount of curl is the least in part B
Means CPU 18 stores data stored in RAM 19.
Decal control device 23 via I / O 21 based on data
To the required curl correction amount, and the decurling control circuit 23
Supplies a drive signal for curl correction to the decurling device 24.
I can. The decurling device 24 is a decurling device as described later.
Rotatable in contact with the belt and this decal belt
A cam roll for pressing the decal roll.
The cam signal is driven by a drive signal applied from the curl control device 23.
The decal roll is rotated by rotating the decal belt.
Press and bend to correct the curl of the paper passing between them.
You. This system is stored in the ROM 20.
Programs and data for
You. Decal control circuit 23 is a cam for driving a cam roll.
The curl specified by the CPU 18 from the motor stop position
The clock from the clock generation circuit 22 corresponding to the correction amount
Count the number and make sure the amount of bending of the decal belt is the required size.
The rotation angle of the cam motor is set so as to be as follows. FIG. 4 illustrates the configuration of the decurling apparatus of this embodiment.
FIGS. 3A and 3B are schematic diagrams illustrating a case where curl correction is not performed.
(B) shows the state when the curl correction is executed.
You. In the figure, reference numeral 30 denotes a sheet detection sensor;
Is a pulley, 33 is a decal belt, 34 is a decal row
, 35 is a shaft, 36 is a cam head, 37 is a cam slot
And 38, a cam motor. This decurling device is installed after the fixing device.
Then, the curl generated by the fixing process is corrected. Big
Belt 33 is stretched over a pair of pulleys 31 and 32.
Decal above the decal belt 33
A roll 34 is provided movably in the up-down direction. This de
The curl roll 34 includes a shaft 35 having a cam head.
And is engaged with the cam roll 37 through the intermediary. The cam roll 37 can be rotated by a cam motor 38.
The cam motor 38 is connected to the above-described decal control circuit.
According to the instruction from 23, the cam roll 37 is at the required angle.
The decal roll 34 rotates the decal belt 33
Is controlled to rotate by pressing. This de
For the curl device, a paper detection sensor 30 for detecting the paper 4 is used.
When the arrival of paper is detected, the decal control circuit 23
According to these instructions, the cam roll 37 rotates by the required angle.
By moving the decal belt 33 and the decal row
The curl correction is performed on the paper 4 passing between the tapes 34. FIG. 7 shows a state in which no curl correction is performed.
In (a), the decal roll 34 is attached to the decal belt 33.
The sheet 4 is passed without applying a pressing force to the sheet 4. Karl Mamoru
When executing the force, as shown in FIG.
Roll 34 responds to an instruction from the decal controller.
The decal belt 33 is pressed by the rotation of the cam roll 37.
I do. As a result, the decal belt 33 and the decal row
Paper 4 passing between the rollers 34 is bent in the opposite direction to the curl.
The curl is corrected. FIG. 5 is a schematic diagram of a first embodiment of the present invention.
Of the gradation data integration routine for each predetermined number of lines
This is the flow chart to explain, here the case of K color
Show. In the figure, B is a predetermined number of lines, and D is one pixel.
Tone data, N is the number of integrated lines, T_KIs gradation day
Data integrated value, X_KIs the storage address of gradation data, and P is cumulative
The number of product lines, Q, is the number of lines per page. First, the initial setting of the decurling device is performed (S
-1), integrated value T of gradation data_KThe gradation per pixel
Data D is added (S-2). Laser scanning synchronization signal
It is determined whether or not the signal is active (S-3).
If so, the flow returns to S-2 (T_K= T_K+ D)
And repeat this. The laser scan synchronization signal is activated.
When it is no longer active, the integrated line number N
It is determined whether or not the number B has been reached (S-4), and N is not equal to B
Then, add +1 to N and +1 to the number of accumulated lines to S-1
Return (S-7). If N = B in S-4, the integration
The number of lines N is set to 0, and the integrated value T of the gradation data is set._KThe gradation
Data storage address X_KAnd X_K+1
(S-5). And the cumulative number of lines P per page
Is determined to be equal to the number of lines Q of (S-
6) If P ≠ Q, return to S-2, P = Q
Ends. This integration routine is repeated for the remaining colors (Y, M,
C) Execute for all, and process the whole color image
And obtains gradation distribution data for each of the divided regions. Figure 6
To explain the curl correction procedure in the first embodiment of the present invention.
-Chart, T_XIs the integrated value of the gradation data for each color
Total value of X_XIs the sum of the integrated values of the gradation data for each color.
Storage address, Z is the last address of the gradation data storage address
It is. First, the initial setting of the decurling device is performed (S
-11), the gradation decal integration routine shown in FIG.
For each color (K, Y, M, C) (S-1
2) The gradation accumulation data of each color is obtained for each of the obtained divided areas.
Total (T_X= T_K+ T_Y+ T_M+ T_C) (S-1)
3). Next, the total value T of the integrated value of the gradation data of each color_XTo
Storage address X of total value of integrated value of gradation data of each color_X
And X_XIs incremented by 1 (S-14). Then, the accumulated data is converted into the decal amount conversion.
Then, the converted decal amount is stored (S-15). This
Of the conversion table stored in the ROM 20 in advance.
It is configured to be performed by backup. After that, the gradation of each color
Storage address X of total value of integrated value of data_XIs gradation day
Judge whether the address is equal to the last address Z of the data storage address.
(S-16), X_XIf Z, return to S-13 and continue
Then X_XDecaling is performed when = Z is reached. The CPU 18 stores the floor stored in the RAM 19.
Decal row in each area on paper based on tone distribution data
So that the tape 34 presses the decal belt 33 optimally.
The roll 37 is rotated. That is, from the CPU 18
The decurling control circuit 23
Is the stop position of the cam motor 38 for rotating the cam roll 37
Calculates the rotation angle from the position and the clock required for that rotation angle
The clock number is taken from the clock generation circuit 22 and this clock number
Generates a driving pulse for rotation of the cam motor 38 and generates a pulse.
The cam motor 38 composed of a motor is rotated. In the first area, the number of clocks is
Is in the initial position (the state shown in FIG. 4A).
Therefore, the number of clocks required for rotational movement from this position
However, the position of the cam roll 37 changes from the next area.
At this time, the rotation is taken from the previous position
This is the number of clocks required for movement. For use after passing through the fixing device
The paper is fed into the decurling device and is
The detection signal of the installed paper detection sensor 30 is used as a trigger.
Then, the CPU 18 reads from the RAM 19 each area of the paper.
Clock acquisition of cam motor 38 according to curl correction amount
The decal control circuit 23 generates a number
Synchronize the corresponding drive pulse with the transport speed of the paper.
Applied to the cam motor 38. As a result, the cam motor 38 rotates to
The paper roll 37 is rotated so that each area of the paper is
Pressing with a predetermined pressing force corresponding to
Rules are modified. In the above embodiment, all the gradation data
Pixels, but only the thin parts and characters of the image
The curl amount is small in the portion where the amount of toner is small. In the second embodiment of the present invention,
Image data is processed as pixels with a certain gradation
Reduce burden. FIG. 7 is provided with decurler means according to the present invention.
Configuration diagram illustrating a second embodiment of an image forming apparatus according to the present invention.
Where 25 is a comparator, and the same reference numerals as in FIG. 2 are the same.
Corresponding to the part. In this embodiment, the image processing apparatus 11 and the buffer
A comparator 25 is installed between the
Only the key data is sent to the buffer 14 and added by the adder 15
It is configured to be. Other processing is performed in the first embodiment.
Same as the example. FIG. 8 shows a first embodiment of the present invention.
An integration routine for gradation data for each line per color
In the flowchart to be described, B is a predetermined number of lines,
C is predetermined gradation data, D is gradation data per pixel,
N is the number of integrated lines, T_KIs the integrated value of the gradation data, X_KIs
The storage address of the gradation data, P is the cumulative number of lines, and Q is 1.
Number of lines per page. First, the initial setting of the decal system is performed.
(S-21) The gradation data D per pixel is a predetermined gradation
It is determined whether or not the data is larger than data C (S-22).
If C, integrated value T of gradation data_KIs the floor per pixel
Key data D is added (S-23), and the laser synchronization signal L
/ S is active (S-2)
4). If D ≦ C in S-22, the process proceeds to S-24.
go. At S-24, the laser synchronization signal L / S is activated.
If yes, return to S-22 and repeat the above procedure.
If not active, the accumulated line number N
It is determined whether or not the number has become equal to the in number B (S-25).
If N ≠ B, the accumulated line number N is incremented by 1 and the accumulated line number is increased.
The number of inputs is incremented by one, and the process returns to S-22. When N = B
Sets N to 0 and the integrated value T of the gradation data_KThe gradation data
Storage address X_KStored in X_KIs incremented by 1 (S-2
6). Then, the accumulated line number P per page
It is determined whether or not the number of lines is equal to (S-27).
If not, return to S-22 and end when equal
I do. Perform this process for each of the remaining colors to
Calculate the integrated value of the gradation data. Using the integrated value of the gradation data, the first
Fixing by executing the same curl correction as in the embodiment
Correct the curl generated by processing. Next, copy both sides
An example of curl correction in the embodiment will be described. Both sides
In the case of copying, first, the floor is divided into predetermined areas on the surface.
The integrated value of the tone data is loaded into the RAM,
Import data in the same way. CPU is the imported surface
And the back side gradation data, the gradation data in the same area
Calculate the difference between FIG. 9 shows a process on a sheet in duplex copying.
FIG. 7 is an explanatory diagram of an example of a difference in toner distribution in directions. same
In the figure, the + direction on the vertical axis indicates the integrated value of the gradation data on the surface.
In the area where there are many, the integrated value of the gradation data on the back side is large in the-direction
Area. Based on this calculation result, the decal
The curl on the front and back is corrected by a screw device. FIG. 10 shows a third embodiment of the present invention.
Explain the configuration of a decurling device that corrects the curl of pea
It is a schematic diagram, (a) is a surface decurling device, (b)
Is a back surface decurling device. In FIG.
0 is a paper detection sensor, 41 and 42 are pulleys, 43 is a deca
Belt, 44 is a decal roll, 45 is a shaft,
46 is a cam head, 47 is a cam roll, 48 is a cam motor.
It is. The data in the + direction of the gradation difference data shown in FIG.
Depending on the data, the curl of the surface is repaired in the same manner as in FIG.
Correct. Also, in FIG.
Sensors, 51 and 52 are pulleys, 53 is a decal belt, 5
4 is a decal roll, 55 is a shaft, 56 is a cam head.
And 57, a cam roll, and 58, a cam motor. The decal device on the back side is a decal belt.
A configuration in which the decal roll 54 is pressed from below the 53
The data in the negative direction of the gradation difference data in FIG.
Correct the curl on the back according to the data. Fig. 11
A flowchart for explaining a curl correction procedure in the third embodiment of the present invention.
-Chart, T_XABIs the integration of the gradation data for each color
Total value of the difference on both sides of the value, X_XABIs T_XABR to store
AM address, T_KAIs the integration of the gradation data of K color on the surface
Sum of values, T_KBIs the integrated value of the gradation data of K color on the back
Total value, T_YAIs the sum of the integrated values of the gradation data of the Y color on the surface
Value, T_YBIs the total value of the integrated values of the gradation data of the Y color on the back side,
T_MAIs the sum of the integrated values of the gradation data of the M color on the surface, T_MB
Is the total value of the integrated values of the gradation data of the M color on the back side,_CAIs a table
Total value of integrated value of gradation data of C color of surface, T _CBIs on the back
The total value of the integrated values of the C color gradation data, and Z is the gradation data
This is the last address of the delivery address. In the figure, the initial setting of the decurling device is
After performing (S-31), the display is performed in the same routine as in FIG.
Integration of gradation data of each color on the front side (S-32) and each color on the back side
(S-33) is performed for each area.
Is the sum T of the gradation accumulation of each color._{XA B}= (T_KA−T_KB) + (T
_YA−T_YB) + (T_MA−T_MB) + (T_CA−T_CB)
(S-34). Next, the gradation accumulation of each color for each totaled area
Value T_XABTo address X_XABStored in the address X_XABTo
The value is incremented by one (S-35). Address X_XABIs gradation data
It is determined whether it is equal to the last address Z of the delivery address (S-
37), X_XABIf ≠ Z, return to S-34 and perform the above processing
Continue, X_XABExecute decal when = Z
(S-38). This decal uses the decurling device of FIG.
In the same manner as in the above embodiment. In each of the above embodiments, the paper is moved in the process direction.
Divided into multiple areas and integrate each gradation data
Then, decal is executed using the integration result.
To divide a part in the lateral direction and perform curl correction
Can also. FIG. 12 is provided with decurler means according to the present invention.
FIG. 9 is a system configuration diagram illustrating a fourth embodiment of the image forming apparatus.
The image area of the paper is divided into N parts in the lateral direction
This is an embodiment in which rule correction is performed. In FIG.₁~ 14_NIs a buff
A, 15₁~ 15_NIs an adder, 16₁~ 16_NIs a latch
The same symbols as those in the circuit and FIG. 2 correspond to the same parts. First,
Calculator 15₁~ 15_NIs one line in the lateral direction of the paper.
Each area when the number of image clocks
Integrates the gradation data of the area. In addition, N may be any number.
However, it is desirably 10 or less, and 3 to 4 is desirable in practice. The buffer 14₁~ 14_NEntered in
Count enable signal C_E1Is the area division control
The image clock signal CL counted by the circuit 13_VIn response
Select the area to be counted, and activate that buffer.
And the gradation data of the area is added to the adder 15.₁~ 15
_NAnd is integrated. Repeat this for the lateral
The toner density distribution (gradation distribution) of each area divided into N directions is
can get. Here, synchronization for each line is performed by laser scanning.
By the L / S signal output from the system I / F 12
Done. Repeat this process for the remaining colors (Y, M, C)
To obtain the gradation distribution data for the entire area of the paper,
The decurling device is driven based on the correction of the curl.
FIG. 13 illustrates the configuration of the decurling apparatus in the present embodiment.
(A) is a side view, and (b) is a schematic view of (a).
It is the front view seen from the arrow direction. In the figure, the same reference numerals as those in FIG.
Subscripts 1 to N are used to divide each member into N parts.
Are shown. As shown in FIG.
Is the same as in the first embodiment, except that the decurling device is
It is divided into N parts in the direction (lateral direction). This decal
Decal Viet 33 constituting the device₁~ 33_NTo decal
Roll 34₁~ 34_NIs the gradation data in the lateral direction.
The curl is corrected by performing the pressing according to the integrated value of. Note that the gradation data stored in the RAM is used.
The decal control is the same as in the previous embodiment, so the description is omitted.
I do. FIG. 14 is a diagram showing the relationship between one color in the fourth embodiment of the present invention.
A description will be given of a gradation data integration routine for each predetermined number of lines.
This is a flow chart that shows the case of K color.
You. In the figure, B is a predetermined number of lines, D is 1
The gradation data per pixel, E is the area number (lateral
Direction), N is the total number of lines, T_KIs the integrated value of the gradation data,
T_EKIs the integrated value of the gradation data in the E-th area, X_EKIs number E
The storage address of the gradation data in the eye area, P is the cumulative line
The number Q is the number of lines per page. First, Deca
The initial settings of the printer are performed (S-41), and the image
An area is selected (S-42), and the gradation data of the E-th area is selected.
The gradation data per pixel is added to the integrated value of the data (S
-43). Next, whether the number of clocks of the predetermined image has been reached is determined.
Is determined (S-44), and the number of clocks has reached a predetermined number.
If not, the flow returns to S-42 to continue the above processing, and
When the number of clocks reaches_EKThe gradation data of the area E is stored at the address.
The integrated value of the data is stored, and +1 is added to the area number E (S
−45), Perform the same gradation data count and specify
It is determined whether or not the number of areas has reached (S-46).
If the number of areas has not been reached, the process returns to S-42 (S-4).
9). When the number of areas is reached, the area number is set to 0.
To (S-47). Then, the accumulated line number P is 1
Judge whether the number of lines per page has become equal to Q
(S-48), if P ≠ Q, the accumulated line number is incremented by one and S-
42, if P = Q, terminates the integration process of the gradation data.
And execute the decal. This decal is the same as above
The description is omitted because it is similar to the example. The method of dividing the image area of the paper into a plurality of
In each of the above process direction and lateral direction
In addition to dividing, predetermined
It can also be divided for each in. That is, lateral
The area divided in the direction is further determined by a predetermined L / S signal.
The paper is divided into a grid by dividing it in the process direction for each number of ins.
Then, the tone data of each section is integrated and the toner density, that is,
The curl amount is calculated, and the
Using a decal roll 34₁~ 34_N
Can operate independently to perform curl correction
You. FIG. 15 shows one color in the fifth embodiment of the present invention.
Routine for integrating gradation data for each predetermined number of lines
The flow chart to explain, here the case of K color
Is shown. In the figure, D is the gradation data per pixel.
, E is the region number in the lateral direction, F is the process direction
Area number, T_EFKIs the gradation data of the E × F-th area of K color
Data integrated value, X_EFKIs the gradation data of the E × F-th region of the K color.
Data storage address, O is the cumulative number of lines for each area, and Q is
The cumulative number of lines, R, is a predetermined number of lines per page.
You. First, the initial setting of the decurling device is performed (S
-51), an image area of the paper is selected (S-52),
Integrated value T of gradation data of E-th area of K color_EFK1 stroke
The tone data per element is added (S-53). next,
Determine whether the number of pixel clocks for each area has reached the specified value.
(S-54), when the predetermined number of clocks has not been reached
Returns to S-52 to continue the above processing, and
When the number of locks is reached, the integrated value of the gradation data up to that point
To X_EFKAddress (S-55), and the cumulative line
The number of lines O has reached the predetermined number of lines P for each area
(S-56), the cumulative number of lines O for each area is
When the constant line number P is reached (O = P), the accumulation for each area
The number of lines O is returned to 0, and the region number E in the lateral direction is set to 0.
(S-57). The cumulative number of lines O for each area is
When the predetermined number of lines P has not been reached (O ≠ P),
Cumulative line number O, predetermined line number P for each area, cumulative line number
(S-59) return to S-52
And the above-described processing is repeated. Next, the cumulative line number Q
Whether the number of lines per page has reached a predetermined number R.
(S-58), and when it has not reached (Q ≠ R),
+1 is added to the area number F in the process direction, and (S-60) S-5
2 and the above-described processing is repeated. Also, the cumulative line number Q is
When the number of lines reaches the predetermined number R (Q = R), this processing is terminated.
And execute the decal. This decal is the same as above
The description is omitted because it is similar to the example. This allows the latte
Fine curl in both the axial and process directions
Can be modified. [0069] As described above, according to the present invention,
Curl caused by image deviation in the process direction of paper, both sides
Curls and bleeding caused by the bias of the image on the front and back of the copy
What kind of curl occurs due to image bias in the lateral direction
The curl can also be corrected properly, always the correct curl
An image forming apparatus equipped with a decurling device that enables correction
Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a basic configuration of an image forming apparatus according to the present invention. FIG. 2 is a system configuration diagram illustrating a first embodiment of an image forming apparatus including a decurling unit according to the present invention. FIG. 3 is an explanatory diagram of a distribution example of an integrated value of gradation data obtained in the first embodiment of the present invention. FIG. 4 is a schematic diagram illustrating a configuration of a decurling apparatus according to a first embodiment of the present invention. FIG. 5 is a flowchart illustrating a routine for integrating gradation data for each predetermined number of lines per color according to the first embodiment of the present invention. FIG. 6 is a flowchart illustrating a curl correction procedure according to the first embodiment of the present invention. FIG. 7 is a system configuration diagram illustrating a second embodiment of an image forming apparatus including a decurling unit according to the present invention. FIG. 8 is a flowchart illustrating a gradation data integration routine for each predetermined line per color according to a second embodiment of the present invention. FIG. 9 is a diagram illustrating an example of a difference in toner distribution in a process direction on a sheet during double-sided copying. FIG. 10 is a schematic diagram illustrating a configuration of a decurling device that corrects curl of double-sided copying according to a third embodiment of the present invention. FIG. 11 is a flowchart illustrating a curl correction procedure according to a third embodiment of the present invention. FIG. 12 is a system configuration diagram illustrating a fourth embodiment of an image forming apparatus including a decurling unit according to the present invention. FIG. 13 is a schematic diagram illustrating a configuration of a decurling apparatus according to a fourth embodiment of the present invention. FIG. 14 is a flowchart illustrating a routine for integrating gradation data for each predetermined number of lines per color according to a fourth embodiment of the present invention. FIG. 15 is a flowchart illustrating a routine for integrating gradation data for each predetermined number of lines per color according to a fifth embodiment of the present invention. FIG. 16 is an explanatory diagram of an example of a conventional decurling device that detects and corrects curl of a sheet after fixing. 17 is a schematic diagram illustrating an example of the decurler device of FIG. [Description of Signs] 1... Image forming means 1a... Image carrier 1b.
..Charging means, 1c ... writing means, 1d ...
Developing unit, 1e Transfer unit, 1f Cleaning unit, 2 Fixing unit, 3 Decal unit, 4 Paper, 5 Image signal source , 6 ...
..Laser scanning synchronization means, 7... Area dividing means,
8 ... gradation data integrating means, 9 ... gradation distribution data storage means, 10 ... decal control means, 11 ...
... Image processing device, 12 Laser scanning system I / F, 13 Area control circuit, 1
4 ... buffer, 15 ... adder, 16 ...
.Latch circuits, 17 data buses, 18
CPU, 19 ... RAM, 20 ... ROM, 2
1 ... I / O, 22 ... Clock generation circuit, 2
3 ... Decal control circuit, 24 ... Decal device, 30 ... Paper detection sensor, 31, 32 ...
Pulley, 33 ... Decal belt, 34 ... Decal roll, 35 ... Shaft, 36 ... Cam head, 37 ... Cam roll, 38 ... Cam motor.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 21/00 370-540 G03G 15/00 510-534 G03G 15/00 303 B65H 29/70

Claims (1)

(57) [Claim 1] An image forming means for forming a toner image according to an image signal and transferring the toner image to a sheet of paper, and applying pressure or applying pressure and heating to form the toner image An image forming apparatus comprising: a fixing unit fixed to the sheet; and a decurling unit that corrects curling of the sheet after the fixing process. The decurling unit includes a plurality of decurling units in a direction orthogonal to a sheet conveying direction.
With a decal belt and decal roll divided into
And an area dividing means for dividing into a plurality of regions in the direction perpendicular to the sheet to the sheet conveying direction, a gradation integrating means gradation data accumulated each image to be formed respectively on the plurality of regions, the Tone distribution data storage means for storing the tone data of the plurality of regions integrated by tone integration means as tone distribution data on the paper; and tone distribution stored in the tone distribution data storage means An image forming apparatus comprising: a decurling control unit that controls a curl adjustment amount of the decurling unit according to data.