JP3535628B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to an electrophotographic process.
Image forming apparatus such as copiers and laser printers equipped with a mechanism
About. [0002] 2. Description of the Related Art As an image forming apparatus of this type, for example,
ー In laser printers, it is installed inside the main unit.
Yellow (Y), magenta on endless belt-shaped paper transport belt
(M), cyan (C) and black (K)
Stations are arranged continuously. Each printing station
The photosensitive drum and laser diode, respectively.
Electrophotographic process consisting of an exposure device, a developing device, etc.
It has a mechanism. Paper transport bells at each of these printing stations
By printing on the paper transported by the
Color images are formed by superimposing these colors.
ing. In such an image forming apparatus, a continuous
The surface potential of the photosensitive drum decreases with use and time,
Deterioration of image quality (image density) due to deterioration of developed toner
In order to prevent
At power-on, toner near-end, toner empty,
Every predetermined number of prints, etc.
Multi-density reference pattern for performing density correction at a predetermined position
Print out the density, detect this density and feed it back.
Thus, the image density is corrected. [0004] Specifically, the density is displayed below the conveyor belt.
CCD (Charge Cou) for reading the density of the correction reference pattern
Printed on conveyor belt with density sensor equipped with pled Device)
The density correction reference pattern is transferred to the CCD of the density sensor.
And convert it to analog data.
After making certain corrections, this data is
By feeding back to the control circuit, for example, each printing
Of the charging potential of the photosensitive drum of the station
Controls grid voltage, laser power, and developing bias
To adjust the image density. [0005] In addition, the lower part of the conveyor belt is long in the main scanning direction.
A conveyor belt cleaning device equipped with a comb blade
The reference pattern for density correction read by the density sensor
Is scraped off with the blade of this conveyor belt cleaning device.
In this case, no toner image remains on the conveyor belt. [0006] However, such an image
In the image forming apparatus, the reference pattern for density correction is set in advance.
Printing is repeatedly performed on the specified part of the specified conveyor belt.
Therefore, this reference pattern for density correction is always
Same main scanning direction (longitudinal direction) of blade of cleaning device
It will be scraped off at the site. Therefore, the transport belt
Partial compared to other parts of the cleaning device blade
Deterioration becomes severe locally, and the concentration increases over time.
The reference pattern for correction cannot be sufficiently scraped.
I will. [0007] With this, the density correction base is placed on the conveyor belt.
Some of the toner in the semi-pattern remains, and it is actually printed on paper.
When the paper is
If it does, the density correction reference
Some of the toner on the pattern adheres, and the back of the paper becomes dirty.
There was a problem that it would. Also, a reference pattern for density correction is provided on the conveyor belt.
If part of the toner of the toner remains,
When printing quasi-patterns, the toner residue on the conveyor belt
Density correction when printing is performed over the remaining part
Since the density of the reference pattern partially changes,
Density sensor cannot read accurate density with density sensor
Cannot be performed accurately. Therefore, the present invention provides a conveyor belt cleaning device.
Cleaning of the conveyor belt by preventing local deterioration of the
Conveyor belt cleaning by eliminating cleaning defects
The service life of the entire printing device can be extended and the printing
Providing an image forming apparatus that can prevent quality deterioration
What you are trying to do. [0010] SUMMARY OF THE INVENTION The present invention relates to an electrostatic latent image holding device.
Charges the surface of the body and exposes the surface potential to a stable area by exposure.
Forms an electrostatic latent image based on print dot data
The printing station for visualizing the latent image is
Placed on the body transport belt and placed on the media transport belt
Visualize the conveyed recording medium with the printing station
In an image forming apparatus for transferring the toner image thus formed,
Predetermined data consisting of test data for detecting print quality
Correction pattern storage means for storing a correction pattern;
Prints the correction pattern from the correction pattern storage
Correction pattern transferred onto the media transport belt by the
Correction pattern output that outputs multiple times at a predetermined timing
Control means and the correction pattern output control means
Correction pattern reading means for reading an image of the correction pattern;
MediumThis correction is provided along the width direction of the conveyor belt.
The image of the correction pattern read by the pattern reading means
Correction pattern removing means for removing from the conveyor belt, and correction
Based on print quality data read by pattern reading means
Output adjusting means for controlling the output from the printing station
When,Correction pattern that can be printed in the width direction of the media transport belt
Means to set the maximum number of
Printing start position where the correction pattern output in
Means for storing the number of corrections;Correction pattern output control means
When outputting the correction pattern,Printing start position memorized
And the number of corrections are read out.
If the number does not match, use another
To the end side from the previous print start position of the correction pattern
The printing start position is shifted by one
If the number matches the set maximum number,
By setting the printing position on the end side to the printing start position,correction
Mark of the previous correction pattern in the longitudinal direction of the pattern removal means
Correction pattern that changes the print position so that the character positions do not overlap
Line printing position changing means. [0011] DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention is applied to a laser printer.
An embodiment in which the present invention is applied will be described with reference to the drawings. FIG. 1 shows a laser pre-conditioner according to this embodiment.
And 21 to 24 are inside the main body of the device.
On the endless belt-shaped paper transport belt 1
4 printing stations. Each of the printing stations 21 to 24 has a photosensitive
Around the ram 3, a charger 4, an exposure device 5, a developing device 6,
The ram cleaner 7 and the static elimination lamp 8 are arranged facing each other, and
The transfer roller 9 is opposed to the drum 3 via the paper transport belt 1.
Orientation. Developing device of each printing station 21 to 23
6 is yellow (Y), magenta (M), and cyan respectively
(C) color toner and print station
24 developing device 6 contains black (K) toner
And is exposed by a developing roller 10 rotatably provided below.
The toner is supplied to the drum 3. A bell is located at the position where the paper transport belt 1 starts to be transported.
A charging device 11 is provided, and a predetermined
A tension roller 12 for applying tension is provided. This
Paper transport belt 1 is made of conductive material and its surface is insulated.
Coated with layers. And one pair so that the conductive material contacts
Are wound around the guide rollers 14 and 15. Below the guide roller 15, a conveyor belt is provided.
Figure printed on the conveyor belt 1 on the upstream side in the conveying direction of the belt 1
Print quality of density correction reference pattern 41 as shown in FIG.
A density sensor 42 for detecting the density as
You. The density sensor 42 is provided with a reference pattern 4 for density correction.
1, a fluorescent lamp that irradiates light, a CCD that reads the reflected light,
It is composed of a heater and the like. In addition, below the guide roller 15, FIG.
As shown in FIG.
Conveying for scraping the primary reference pattern 41 from the conveying belt 1
A belt cleaning device 43 is provided. This transport
The conveyor belt cleaning device 43 is provided for cleaning the surface of the conveyor belt 1.
Blade that elastically abuts in the width direction (main scanning direction)
43a. The density correction reference pattern 41 is dark.
After being read by the degree sensor 42, the conveyor belt 1
By being further transported in the mark direction, the blade 43a
Is scraped off at the abutment. Below the paper transport belt 1, there is a recording
A paper feeder 19 containing stacked paper 18 is detachably installed.
I am. On the upper side of the paper feeding device 19, the recording paper 18 is placed.
Recording on the feed roller 23 and the conveyance path 13 to be picked up
A transport roller 24 for guiding the sheet 18 is provided. In the vicinity of one guide roller 14, a paper feeding device
The recording paper 18 from the tray 19 to the end of the paper transport belt 1
A transfer path 13 is provided. In addition, the other guide
The fixing device 20 is arranged close to the outside of the roller 15.
You. This device is fed from a paper feeding device 19.
The recording paper 18 is transported by the belt charger 11 to the paper transport belt 1.
After the image has been absorbed, the yellow image
Performs transfer and transfers the magenta image at print station 22
And transfer the cyan image at the printing station 23.
By doing so, color printing is performed by overlapping colors,
The sheet is thermally fixed by the fixing device 20 and is discharged to the discharge unit 21 or 22.
It has become so. FIG. 2 shows the color image forming apparatus shown in FIG.
25 is a block diagram showing a circuit configuration, and 25 is a control unit main body.
CPU (Central Processing Unit) 26
R storing program data for controlling each part
OM (read only memory), 27 is data processing
(Random) with memory used for
Access memory), 28 is a mechanical controller, 29
Is connected to a host computer 34 via a communication line.
I / F (interface), 30 is I / O (input / output)
Port. CPU 25, ROM 26, RAM 2
7. I / O port 28, I / F 29 and bus line 31
Are electrically connected to each other. The mechanical controller 28 has the printing
Drive the guide rollers 15 in the stations 21 to 24
A belt transport motor 4 for driving the transport belt 1
4 are connected. Further, the detection from the concentration sensor 42 is performed.
The exposure of each printing station 21 to 24 based on the output
The grid voltage of the scorotron and the exposure of the charging potential of the drum 3
Laser power of optical device 5, developing bias of developing device 6, etc.
Density correction circuit that corrects print density by controlling
45 are connected. In addition, when the fixing device 20 is connected
I have. The I / O port 30 has the above-described concentration sensor.
The amount of toner in the sensor 42 and the developing device 6 is detected to detect toner.
Near end (immediately before toner empty), toner end
Is connected to the toner sensor 46 that notifies
You. In the ROM 26, a preset printing
The density correction reference pattern 41 is stored as data.
I have. This density correction reference pattern 41 is specifically
As shown in FIG. 3, the yellow (Y) row
Square in the center (M), cyan (C) and black (K) columns
The test data of the shapes are arranged, and each column has its concentration
(Print quality) is 25 in the sub-scanning direction (belt conveyance direction).
%, 50%, and 100%.
Data. The CPU 25 has four colors and three types.
Density = Density complementation of 12 rectangular data as one unit
The main reference pattern 41 is read from the ROM 26,
Each printing station 21 to 24 is controlled based on the printing data.
The reference pattern 41 for density correction on the conveyor belt 1.
It is designed to be printed. Note that this density correction reference pattern 41 and
Then, as shown in FIG. 4, the yellow (Y) column, magenta
Row (M), row cyan (C), row black (K)
100% in the sub-scanning direction (belt conveyance direction)
Three rectangular test data to be 0% and 25%
May be arranged side by side. The CPU 25 operates when the power is turned on or when the toner
At the end, at the time of toner empty, every time a predetermined number of sheets are printed, etc.
Then, the density correction control as shown in FIG.
I have. That is, the number of density corrections in ST (step) 1
X = 0, the main scanning direction of the paper transport belt 1 (break
Reference pattern for density correction that can be printed in
Setting of the maximum number n of CCDs and setting of the CCD of the density sensor 42.
Perform initial settings such as startup. Then, CC at ST2
It is determined whether setup of D has been completed. This and
When it is determined that the CCD setup has been completed
Hits the density correction reference pattern 41 last time in ST3.
The read out position and the density correction frequency X are read from the RAM 27.
You. Then, in ST4, whether or not the first density correction is performed
That is, it is determined whether the number X of density corrections is 0 or n.
You. When the number of times of density correction X = 0, density correction has not yet been performed once.
Is not performed, and the number of times of density correction X = n (FIG. 7)
Is n = 9), the density correction is performed as shown in FIG.
Reference pattern 41 from one end in the main scanning direction to the other end
When printing at the most other end position when printing one way
It is. At this time, the first density correction, that is, the density
If it is determined that the number of corrections X is 0 or n, ST5
To set the number of times of density correction X = 1, and to set the density correction in ST6.
The print data of the primary reference pattern 41 is read from the ROM 26.
Out of the conveyor belt 1 as shown in FIG.
This density correction at the first position, one end in the main scanning direction
And print the reference pattern 41 (correction pattern
Output control means), and sets the launch start position at this time in RAM 2
7 is stored. Next, in ST8, the printed image is printed on the conveyor belt 1.
The density of the corrected density correction reference pattern 41 is
Read by 2 CCD. Analog data from this CCD
Data is converted to digital data and corrected
Convert to voltage level. This density correction reference pattern 4
Then, when the transport belt 1 is further transported,
By the blade 43a of the feeding belt cleaning device 43
It is scraped off. Then, in ST9, the data is converted in ST8.
The CCD output voltage of the density sensor 42 of each color is lower than a predetermined voltage.
Above, for example, it is determined whether it is 3 V or more. This and
3V or more for all colors and all densities
If it is determined that this is the case, the density correction processing ends. this
The predetermined voltage can be set freely according to the CCD reading accuracy, etc.
Good. In addition, it is judged that there is one that is not more than 3V
If so, in ST10, the printing station that prints the color
The density of the image is corrected (output adjustment means). For example,
The image forming device 6 is controlled to increase the developing bias by 25 V.
You. Then, the process returns to ST3. On the other hand, the first correction is not performed in ST4.
Is determined, that is, even if the density correction frequency X is 0, n
If it is determined that this is not the case, the density correction reference is made in ST11.
The launch start position of pattern 41 is the previous launch start position
To the other end in the main scanning direction from the previous reference pattern for density correction
Shift so that it does not overlap 41. That is, the previous hit
1 step from the output start position (reference pattern 1 for density correction)
), That is, the launch start position for 64 × 4 dots
Shift the correction pattern printing start position
Stage). Subsequently, the number of times of density correction X is incremented in ST12.
And the process proceeds to ST6. Then, in ST7, from the previous launch position
Density correction from the starting position shifted by one step
The reference pattern 41 is printed. Like this
Printing of the second and subsequent density correction reference patterns 41
Indicates that the launching start position is one space as shown by the dotted line in FIG.
The shift is performed in steps of one step.
The (n + 1) th print is returned to the first position and printed.
You. In the embodiment of the present invention having such a configuration,
For example, a mark of A4 size width (about 2470 dots)
Mainly running on conveyor belt 1 of laser printer capable of printing with character width
A 64 × 4 dot density correction reference pattern is printed in the inspection direction.
When the power is first turned on, printing on paper
Before the start, the first density correction control is performed. this
In the case, a maximum of nine
Since the reference pattern for density correction can be printed,
In this case, n = 9 is set. More specifically, as shown in FIG.
The reference pattern 41 is printed on one end of the conveyor belt.
The density is read by the density sensor 42. this
Density correction is performed according to the output of the density sensor 42.
The reference pattern 41 for density correction is a conveyor belt cleaning.
Is scraped off by the blade 43a of the ganging device 43. this
In this case, only one end of the blade 43a is scraped off.
You. Thereafter, every predetermined number of prints (for example, 10
Every 00 sheets) and the detection result from the toner sensor
At the time of toner near end, toner empty, etc.
Next, density correction control is performed. In the second density correction,
Start position of the first printing of the density correction reference pattern 41
1 step to the other end in the main scanning direction
A density correction reference pattern 41 is printed at the position. this
Therefore, in this case, the second density correction reference pattern 4
1 is the first density correction from one end of the blade 43a.
It is scraped off at a position shifted by the use reference pattern 41 minutes.
As a result, the first blade use position and the second
It is possible to prevent the card use positions from overlapping. The third and subsequent density corrections are similarly performed for the previous density correction.
The printing is shifted by the correction reference pattern 41 minutes.
Therefore, the same position of the blade 43a must be used continuously.
And not. Therefore, the blade 43a is moved in the main scanning direction (the blade).
Used evenly in the longitudinal direction of the
As shown, only the same position of the blade 43a is locally inferior.
Can be prevented. As a result, the conveyor belt clear
The overall life of the cleaning device 43 can be extended.
In both cases, the transport bell caused by local deterioration of the blade 43a
1 can eliminate the cleaning failure,
Deterioration of print quality can be prevented. As the density correction reference pattern 41,
As shown in FIG. 4, the print density is the lightest at the head in the transport direction.
Print data is arranged, and the print data with the highest print density
By using the array, it is possible to gradually correct the density
The blade 43a is adapted to the toner of the reference pattern 41,
Print data with the highest print density
The burden on the door 43a can be reduced. When the ninth printing is completed,
The next density correction reference pattern is the main scanning method of the conveyor belt 1.
At the most end position, ie, the first position.
It is. Next, the present invention is applied to a laser printer.
Another embodiment will be described with reference to the drawings. What
Note that, in the present embodiment,
The same parts as those described above are given the same reference numerals and detailed description is omitted.
I do. This embodiment is different from the above embodiment in that
What is different is the launch position of the density correction reference pattern 41.
From the previous printing position to one end of the conveyor belt 1
Instead of shifting one step at a time to
The position is shifted two steps at a time,
Reference pattern 41 for density correction while leaving a space between turns
After printing once in the main scanning direction by printing
From the next time, print in the space between
The point is that printing is performed evenly. However, on this occasion
In this case, the density compensation for printing in the main scanning direction of the paper transport belt 1 is performed.
It is necessary to set the maximum number n of regular reference patterns to an odd number
is there. Specifically, the CPU 1 according to the present embodiment
1 indicates that the power is turned on, the toner is near
At the time of printing, the density compensation as shown in FIG.
Correct processing is performed. That is, in ST21, the number of density corrections P =
0, printing in the main scanning direction of the paper transport belt 1
When the maximum number of density correction reference patterns is 2n + 1
N, CCD setup of density sensor 42, etc.
Make the initial settings for. Subsequently, in ST22, the CCD is set.
It is determined whether the setup has been completed. At this time, CC
If it is determined that the setup of D has been completed, ST2
3 is the position where the density correction reference pattern 41 was previously printed.
The position and the number of density corrections P are read from the RAM 27. Then, in ST24, the first density correction is performed.
No, that is, whether the number P of density corrections is 0 or 2n.
Refuse. When the number of times of density correction P = 0, the density has not yet been
This is the case where no correction has been made, and the number of times of density correction P = 2n
(FIG. 9 shows the case where n = 4), as shown in FIG.
The reference pattern 41 for degree correction is different from one end in the main scanning direction.
The position on the other end side when one print is performed on the end side (in FIG. 9,
Is the position of one step end from the ninth case)
Is the case of the eighth printing). At this time, the first density correction, that is, the density
If it is determined that the number of corrections P is 0 or n, ST2
5, the number of density corrections is set to P = 1, and the density is corrected in ST26.
The print data of the degree correction reference pattern 41 from the ROM 26
And at ST27, as shown in FIG.
1 at the first position, that is, one end side in the main scanning direction.
Print the reference pattern 41 for correction
Turn output control means).
It is stored in the AM 27. Next, printing is performed on the conveyor belt 1 in ST28.
The density of the reference pattern 41 for density correction
It is read by the CCD 42. Analog data from this CCD
Data is converted to digital data and corrected
To a voltage level. This density correction reference pattern
41, after that, when the transport belt 1 is further transported,
By the blade 43a of the conveyor belt cleaning device 43
It is scraped off. Then, in ST29, converted in ST28.
CCD output voltage of the density sensor 42 of each color
As described above, it is determined whether the voltage is 3 V or more, for example. This and
3V or more for all colors and all densities
If it is determined that this is the case, the density correction processing ends. this
The predetermined voltage can be set freely according to the CCD reading accuracy, etc.
Good. In addition, it is judged that there is one that is not more than 3V
If so, in ST30 a printing station for printing that color
The density of the image is corrected (output adjustment means). For example,
The image forming device 6 is controlled to increase the developing bias by 25 V.
You. Then, the process returns to ST23. By the way, the first correction is performed in ST24.
Is determined, that is, even if the density correction frequency X is 0, 2
If it is determined that it is not n, the previous density correction is performed in ST33.
Reference pattern 41 at the position of the other end in the main scanning direction.
Whether or not printing is performed, that is, P = 2n + 1 (in the case of FIG. 9,
Ninth) is determined. At this time, the number of density corrections P = 2n + 1
If it is determined that the reference pattern for density correction is
Start position of the feed belt 41 in the main scanning direction of the conveyor belt 1.
From the most end position (launch position when P = 1)
One step to the other end in the scanning direction (reference pattern for density correction)
1), that is, shift by 64 × 4 dots
(Correction pattern printing start position changing means). Then, ST
At 33, the number of times of density correction is set to P = 2, and the process of ST26 is performed.
Move on to In ST31, the number of density corrections P = 2n
If it is determined that it is not +1 for density correction in ST34.
Starting the launching position of the reference pattern 41 from the previous launching
2 steps from the position to the other end in the main scanning direction (the density correction base
2 quasi-patterns), that is, 64 x 4 x 2 dots
Shift the correction pattern printing start position
Stage). Subsequently, 2 is added to the number of density corrections P in ST35.
Then, the process proceeds to ST26. In this way, every two patterns in the main scanning direction
The reference pattern 41 for density correction is printed one way.
No two patterns in the main scanning direction at positions separated from the next
It is shifted and printed. And two kinds of density correction
When the printing of the reference pattern 41 is completed,
Printing is performed uniformly in the main scanning direction. After that,
Also, the most end side of the conveying belt 1 in the main scanning direction (when P = 1)
Print position). In the embodiment of the present invention having such a configuration,
For example, a mark of A4 size width (about 2470 dots)
Mainly running on conveyor belt 1 of laser printer capable of printing with character width
A 64 × 4 dot density correction reference pattern is printed in the inspection direction.
When the power is first turned on, printing on paper
Before the start, the first density correction control is performed. this
In the case, a maximum of nine
Since the reference pattern for density correction can be printed,
2n + 1 = 9, that is, n = 4. More specifically, as shown in FIG.
The reference pattern 41 is printed on one end of the conveyor belt.
The density is read by the density sensor 42. this
Density correction is performed according to the output of the density sensor 42.
The reference pattern 41 for density correction is a conveyor belt cleaning.
Is scraped off by the blade 43a of the ganging device 43. this
In this case, only one end of the blade 43a is scraped off.
You. Thereafter, every predetermined number of prints (for example, 10
Every 00 sheets) and the detection result from the toner sensor
At the time of toner near end, toner empty, etc.
Next, density correction control is performed. Reference for the second density correction
The pattern 41 is a transfer belt from the first printing start position.
Printing from the position shifted by 2 steps to the other side in the main scanning direction of 1
Is done. For this reason, in this case, the second density correction base
The quasi-pattern 41 is more sufficient than one end of the blade 43a.
It is scraped off at a worn position. As a result, the first shake
The blade use position and the second blade use position overlap
Can be prevented. Thereafter, the density correction reference pattern 41 is
Printed with two steps shifted to the other end in the scanning direction.
Of the reference pattern 41 for density correction
When printed on the edge side, the 10th reference pattern for density correction
41 is the main running of the conveyor belt 1 from the first printing start position.
Printing is performed from a position shifted by one step toward the other end in the inspection direction.
  The eleventh density correction reference pattern 41 is 1
2 steps from the 0th density correction reference pattern 41
Between the second and third printing positions
Is written. Then, the eighth density correction reference pattern 4
1 is printed on the other end of the conveyor belt 1,
1 is uniformly printed in the main scanning direction.
The same position of a is not used consecutively. For this reason, the blade 43a moves in the main scanning direction.
Used evenly, the blade 43a
It is possible to prevent only the same position from locally deteriorating. This
As a result, the overall life of the conveyor belt cleaning device 43 is reduced.
The life of the blade 43a can be extended.
Eliminates poor cleaning of conveyor belt 1 due to localized deterioration
To prevent print quality degradation.
Can be. In the above embodiment of the present invention,
Set the printing start position of the density correction reference pattern to the conveyor belt 1.
Described the case of regularly shifting in the main scanning direction of
It is not necessarily limited to this.
The print start position of the semi-pattern is not based on the numbers in the random number table.
May be used. [0058] According to the present invention, as described above,
The transport belt cleaning device is transported while preventing local deterioration.
By removing the cleaning failure of the feed belt,
The service life of the entire belt cleaning device can be extended.
And prevent deterioration of print quality
An image forming apparatus can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a configuration of a main part of an embodiment of the present invention. FIG. 2 is a block diagram showing a circuit configuration of a control unit of the laser printer shown in FIG. FIG. 3 is a diagram illustrating an example of a correction pattern when the density is increased in the belt conveyance direction in the present embodiment. FIG. 4 is a diagram showing an example of a correction pattern when the density is reduced in the belt conveyance direction in the embodiment. FIG. 5 is a diagram illustrating an operation in the present embodiment. FIG. 6 is a flowchart showing density correction control performed by a CPU according to the embodiment. FIG. 7 is a view for explaining a print position of a correction pattern according to the embodiment. FIG. 8 is a flowchart showing density correction control performed by a CPU according to another embodiment of the present invention. FIG. 9 is a view for explaining a print position of a correction pattern according to the embodiment. [Description of Signs] 1 ... Paper transport belt (medium transport belt) 21 to 24 ... Printing station 3 ... Photosensitive drum (electrostatic latent image holder) 41 ... Correction pattern 42 ... Density sensor (correction pattern reading means) 43 ... Transport Belt cleaning device (correction pattern removing means)

Continuation of the front page (56) References JP-A-6-289670 (JP, A) JP-A-6-130767 (JP, A) JP-A-1-116658 (JP, A) JP-A-62-2967 (JP) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 303 B41J 29/46 G03G 15/01 G03G 21/10 G03G 21/00 370-512

Claims (1)

(57) [Claim 1] A surface of an electrostatic latent image holding member is charged, and an electrostatic latent image based on print dot data is formed by exposure to a stable area of the surface potential, and the electrostatic latent image is formed. A printing station for visualizing the latent image is arranged on an endless belt-shaped medium transport belt,
In an image forming apparatus for transferring a toner image visualized by the printing station onto a recording medium placed and transported on the medium transport belt, a predetermined data comprising test data for detecting print quality. Correction pattern storage means for storing a correction pattern; and a correction pattern from the correction pattern storage means by the printing station.
A plurality of times performing correction pattern output control means a correction pattern output to be transferred to the medium conveying belt at a predetermined timing, a correction pattern reading means for reading an image of transcription correction pattern in this correction pattern output control means, the medium < a correction pattern removing unit provided along the belt width direction of the transport belt and removing an image of the correction pattern read by the correction pattern reading unit from the medium transport belt; and a print read by the correction pattern reading unit. Output adjusting means for controlling output from the printing station based on quality data, and capable of printing in the width direction of the medium transport belt.
Means for setting a maximum number of the correction patterns,
The correction pattern output by the positive pattern output control means
Means for storing the printed start position and the number of corrections,
When the correction pattern output control means outputs a correction pattern, the stored print start position and the number of corrections are read.
And the number of corrections matches 0 and the set maximum number
If not, from one end side of the media transport belt to the other end side
From the print start position of the previous correction pattern,
The printing start position is shifted by one
If the number matches the set maximum number,
The printing position at one end of the belt is set as the printing start position.
More, the image forming apparatus is characterized by providing a correction pattern printing position changing means for changing the printing position to the longitudinal direction do not overlap the printing position of the previous correction pattern of the correction pattern removing means.