JP2003098792A - Color slippage correcting device for color image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color slippage correcting device of high precision which can always execute color slippage correction at a proper timing without making the down time longer than necessary or bringing about a color slippage variation exceeding an allowable value. SOLUTION: The color slippage correcting device for a color image forming apparatus is provided with; a first temperature detection means 12a which detects the ambient temperature of one of image forming means 102a to 102d, an endless belt means 3, and transfer means 103a to 103d; a second temperature detection means 13a which detects the temperature of the inside of the color image forming apparatus; and an operation timing determining means 14 which determines the operation timing of a color slippage correcting means. The operation timing determining means 14 determines the operation timing on the basis of at least one of detected temperature variations of the first and second temperature detection means 12a and 13a and the detected temperature difference between the first and second temperature detection means 12a and 13a or the variation of the detected temperature difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color printer,
The present invention relates to a color misregistration correction apparatus for a color image forming apparatus such as a color copying machine, and more particularly to a color misregistration correction apparatus for an electrophotographic color image forming apparatus having a plurality of image forming units.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic color image forming apparatus has a plurality of image forming means for speeding up and sequentially transfers images of different colors onto a recording material held on a conveyor belt. Various methods have been proposed.

However, as a problem of the apparatus having a plurality of image forming means, due to mechanical precision and the like, the movement unevenness of the plurality of photosensitive drums and the conveyor belt and the outer peripheral surface of the photosensitive drum at the transfer position of each image forming means are caused. It is known that the shift amount of the transport belt and the shift amount of the transport belt are different for each color, and when the images are superposed, they do not match each other and a color shift occurs.

Further, in particular, in an apparatus having a plurality of image forming means having a laser scanner and a photosensitive drum, there is an error in the distance between the laser scanner and the photosensitive drum in each image forming means. Difference, the scanning width of the laser on the photosensitive drum is different, and color misregistration occurs.

An example of color misregistration is shown in FIG.

FIG. 11 is a diagram for explaining various color shifts.

Reference numeral 20 indicates the original image position, 21a, 21
b, 21c, and 21d indicate image positions when color misregistration occurs.

Note that (b) and (c) show the case where there is a color shift in the main scanning direction, but for the sake of explanation, the two lines are drawn separately in the carrying direction.

(A) shows an inclination deviation of the main scanning line, which occurs when there is an inclination between the optical section and the photosensitive drum.

On the other hand, the contents of the color misregistration correction operation are as follows.
For example, it is possible to make corrections in the arrow direction by adjusting the positions of the optical unit, the photosensitive drum, and the lens.

(B) shows a color shift due to a variation in the main scanning line width, which is caused by a difference in the distance between the optical section and the photosensitive drum.

This is likely to occur when the optical unit is a laser scanner.

On the other hand, the contents of the color misregistration correction operation are as follows.
For example, by adjusting the positions of the optical unit, photosensitive drum, and lens, or by finely adjusting the image frequency (increasing the frequency when the scanning width is long) and changing the length of the scanning line, Fix it and so on.

The unillustrated means for making these electrical and mechanical adjustments is referred to as color misregistration correction means.

(C) shows a writing start position error in the main scanning direction.

On the other hand, the contents of the color misregistration correction operation are as follows.
For example, if the optical unit is a laser scanner, the writing start timing from the beam detection position is adjusted to make correction in the arrow direction.

(D) shows a write start position error in the paper transport direction.

On the other hand, the contents of the color misregistration correction operation are as follows.
For example, it is possible to make corrections in the direction of the arrow by adjusting the timing of writing each color from the detection of the leading edge of the paper.

In order to correct these color misregistrations, specifically, a color misregistration detection pattern is formed for each color on the conveyor belt, and a pair of optical sensors provided on both sides of the downstream side of the conveyor belt. The above-mentioned various adjustments are performed according to the detected shift amount.

An example of the color shift detection pattern will be described with reference to FIG.

FIG. 12 is a diagram for explaining the color shift detection pattern.

22a, 22b, 22c, 22d, 23
a, 23b, 23c, and 23d are patterns for detecting the amount of color misregistration in the paper transport direction, and 24a, 24b, 24c, and
Reference numerals 24d, 25a, 25b, 25c, and 25d are patterns for detecting the amount of color misregistration in the main scanning direction orthogonal to the paper conveyance direction.
Each of a to d of 4 and 25 represents black (hereinafter Bk), yellow (hereinafter Y), magenta (hereinafter M), and cyan (hereinafter C).

Tsf1-4, tmf1-4, tsr1-
4, tmr1 to 4 indicate the detection timing of each pattern,
The arrow indicates the moving direction of the conveyor belt.

The moving speed of the conveyor belt is vmm / s, Bk
Is the reference color, and the theoretical distance between each color of the paper transport direction pattern and the Bk pattern is dsYmm, dsMmm, dsC.
mm, the measured distance between the pattern for the sheet conveyance direction of each color and the pattern for the main scanning direction is dmfBkm, d
mfYmm, dmfMmm, dmfCmm, dmrBk
mm, dmrYmm, dmrMmm, dmrCmm.

With Bk as the reference color, the color shift amount δes of each color in the transport direction is δesY = v * {(tsf2-tsf1) + (tsr2-tsr1)} / 2−dsY (Equation 1) δesM = v * {(Tsf3-tsf1) + (tsr3-tsr1)} / 2−dsM (formula 2) δesC = v * {(tsf4-tsf1) + (tsr4-tsr1)} / 2−dsC (formula 3).

With respect to the main scanning direction, the color shift amounts δemf and δemr of the respective right and left colors are as follows: dmfBk = v * (tmf1-tsf1) (Equation 4) dmfY = v * (tmf2-tsf2) (Equation 5) dmfM = v * (Tmf3-tsf3) (Formula 6) dmfC = v * (tmf4-tsf4) (Formula 7) and dmrBk = v * (tmr1-tsr1) (Formula 8) dmrY = v * (tmr2-tsr2) (Formula 9) dmrM = v * (tmr3-tsr3) (Formula 10) dmrC = v * (tmr4-tsr4) (Formula 11) From δemfY = dmfY-dmfBk (Formula 12) δemfM = dmfM-dmfBk (Formula 13) δemfC- dmfBk (Equation 14) and δemrY = dmrY−dmrBk (Equation 15) δemrM = dmrM−dmrBk (Expression 16) δemrC = dmrC−dmrBk (Expression 17), the deviation direction can be determined from the positive / negative of the calculation results of Expressions 12 to 17, the deviation of the writing position is detected from δemf, and the deviation of the main scanning width from δemr−δemf. Detect
Correct each.

Color misregistration detection patterns are formed on the conveyor belt, and various adjustments are performed. The timing of execution of this color misregistration correction is when the power is turned on or when an image forming means such as a consumable photoconductor drum is inserted or removed. Or when it is determined according to the detected temperature fluctuation amount of the temperature sensor installed inside the apparatus.

Among these, what is important is the execution timing of the color misregistration correction determined according to the detected temperature fluctuation amount and the like.

The reason is that the amount of color misregistration generally varies with temperature variation.

For example, in a general color image forming apparatus, during printing, the belt for conveying the recording material is warmed by the fixing device, and the heated belt raises the roller on which the belt is suspended. Warm.

The surface of the roller is covered with a thin rubber layer, and the thickness of the rubber layer increases as the temperature rises.

When the diameter of the driving roller for driving the belt increases, the speed of the belt increases and color misregistration occurs.

As described above, the detected temperature fluctuation amount has an important relationship with the color misregistration fluctuation amount (hereinafter referred to as the color misregistration fluctuation amount).

Therefore, the timing for executing the color misregistration correction is determined according to the detected temperature fluctuation amount and the like.

[0035]

However, the above-mentioned conventional example has the following drawbacks.

The relationship between the temperature variation detected by the temperature sensor inside the apparatus and the color shift variation depends on the installation environment of the apparatus, the printing speed, the printing interval, the sheet conveying path, the sheet size, etc. When the execution timing of the color misregistration correction operation is determined according to the detected temperature fluctuation amount of each temperature sensor, the color misregistration correction operation is not always executed at an appropriate timing.

That is, when the temperature fluctuation inside the apparatus is small (slow), the color shift fluctuation amount becomes larger than the detected temperature fluctuation amount, and the execution timing of the color shift correction operation is delayed,
There was a case where the amount of color misregistration variation exceeded the allowable amount.

When the temperature variation inside the apparatus is large (fast), the color misregistration variation amount becomes smaller than the detected temperature variation amount, and the color misregistration correction operation is performed at an unnecessarily fast timing to perform continuous printing. The downtime (print operation interruption time) was increased, resulting in poor performance.

The present invention has been made to solve the above problems, and is necessary even when the relationship between the temperature variation amount detected by the temperature sensor inside the apparatus and the color misregistration variation amount differs due to various printing conditions. An object of the present invention is to provide a highly accurate color misregistration correction device that prevents the above-mentioned increase in downtime and the occurrence of a color misregistration variation amount exceeding an allowable amount, and always executes a color misregistration correction operation at appropriate timing.

[0040]

Therefore, in the present invention, by providing a color misregistration correction device for a color image forming apparatus as described in any of the following items (1) to (4), the above-mentioned object is achieved. Is to achieve.

(1) A plurality of image forming means each having an optical portion and a latent image forming medium, an endless belt means for sequentially passing through the plurality of image forming means, and the formed image on the endless belt. Means or a plurality of transfer means for transferring onto a recording material which is conveyed while being held on the endless belt means, a driving means for driving the endless belt means, and a color shift detection on the endless belt means Color misregistration correction means for electrically and mechanically correcting the color misregistration based on the detection result of the color misregistration detection pattern,
A color misregistration correction device for a color image forming apparatus, comprising: first temperature detecting means for detecting a temperature in the vicinity of one of the image forming means, the endless belt means, and the transfer means; Second temperature detecting means for detecting the temperature in the color image forming apparatus, in addition to the temperature detecting means,
An operation timing determining unit that determines an operation timing of the color misregistration correcting unit, wherein the operation timing determining unit determines at least one of the temperature fluctuation amounts detected by the first and second temperature detecting units; First and second
The color misregistration correction device for a color image forming apparatus, wherein the operation timing is determined based on the detected temperature difference of the temperature detection means or the variation amount of the detected temperature difference.

(2) The operation timing determining means has the first or the second temperature detecting means compared to the first or second temperature detecting means when the detected temperature difference or the variation amount of the detected temperature difference is smaller than when it is large. 2. The color misregistration correction device for a color image forming apparatus according to item (1), wherein the color misregistration correction device is operated at a timing when the detected temperature fluctuation amount of the temperature detection device 2 is small.

(3) The color image forming according to item (1), wherein the first temperature detecting means detects the surface temperature of a belt driving roller on which the endless belt means is suspended. Device color shift correction device.

(4) The color misregistration correction device for a color image forming apparatus according to item (1), wherein the first temperature detecting means detects the ambient temperature of the optical section.

With the above configuration, even when the relationship between the temperature variation amount detected by the temperature sensor inside the apparatus and the color misregistration variation amount differs due to various printing states, the downtime increases more than necessary and the color misregistration exceeds the allowable amount. Prevents fluctuations from occurring,
The color misregistration correction operation is always executed at an appropriate timing.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to a plurality of examples.

The color image forming apparatus of this embodiment is
The color image forming apparatus is provided with image forming means for four colors, that is, yellow Y, magenta M, cyan C, and black Bk.

(First Embodiment) First, a first embodiment will be described with reference to FIGS.

FIG. 1 is a diagram for explaining the entire image forming apparatus according to the embodiment of the present invention.

1a, 1b, 1c and 1d are photosensitive drums (a, b, c and d) which are latent image forming media for forming electrostatic latent images.
Are for Y, M, C, and Bk respectively), 2a, 2b, 2
c, 2d are laser scanners (a, b, c, d are Y, M, C, respectively) that perform exposure according to image signals and form electrostatic latent images on the photosensitive drums 1a-1d. (For Bk), the photosensitive drums 1a to 1d, and the laser scanner 2
a to 2d, the image forming means 102a, 102
b, 102c, 102d.

Reference numeral 3 is an intermediate transfer belt which is an endless belt means for sequentially transferring and conveying the toner images formed on the photosensitive drums 1a to 1d, and 4 is connected to a driving means 19a composed of a motor and gears and the like. The belt drive rollers 5 for driving the transfer belt 3 rotate according to the movement of the intermediate transfer belt 3, and the belt driven rollers 6 for applying a constant tension to the intermediate transfer belt 3 are conveyed by the intermediate transfer belt 3. Secondary transfer roller for transferring the toner image to the paper, 7
Is a paper cassette, 8 is a fixing device that melts and fixes the toner image transferred onto the paper with heat, and 9 is a double-sided unit that reverses the front and back sides of the paper to print on both sides of the paper.
Is a flapper that switches the transport path when the paper is sent to the duplex unit 9, and 11 is a pair that is provided on both sides of the intermediate transfer belt 3 that detects the color misregistration detection pattern formed on the intermediate transfer belt 3. Optical sensor, 12a,
The belt drive roller temperature sensor, which is the first temperature detecting means for detecting the surface temperature of the drive roller 4, 13a is an environment sensor, which is the second temperature detecting means for detecting the temperature inside the printer.

103a, 103b, 103c, 103d
Is a transfer unit that transfers each formed image onto the intermediate transfer belt 3.

Arrows indicate the flow of sheet conveyance.

FIG. 2 is a diagram for explaining the entire control section according to the embodiment of the present invention.

Reference numeral 14 is a CPU which is an operation timing determining means and also controls and manages the entire apparatus, 15 is a host I / F unit which controls communication between a printer and a PC, and 16 is print data, various parameters and various information. And the like, 17 is an image control unit that converts print data sent from the PC to the printer into data suitable for the printer engine system, 18 is a sensor control unit that detects the state of each unit of the printer, and 19 is , A drive control unit 19a that controls the drive of actuators of the printer engine, laser, high-voltage power supply, and the like.
.About.1d and a belt driving roller 4 are driving means including a motor and a gear.

Next, the operation of the image forming apparatus will be described.

Print data from the PC is transferred to the host I / F.
When the image data is sent to the printer through the unit 15, the image control unit 17 converts the print data into data suitable for the printer engine system.

When the converted data is held in the memory 16 and a so-called printable state is reached, the drive control section 19 causes the drive means 19 including a motor and gears.
a is driven, and the photosensitive drums 1a to 1d and the belt driving roller 4 connected to the driving means 19a also start driving.

Next, the image signals of the respective colors are sent to the laser scanners 2a to 2d of the respective colors, electrostatic latent images are formed on the photosensitive drums 1a to 1d, the toner is developed by a developing device (not shown), and the transfer means 103a. The image is transferred onto the intermediate transfer belt 3 by ˜103 d.

In this embodiment, as shown in FIG. 1, Y,
Images are sequentially formed in the order of M, C, and Bk.

At the same time, at the same time as the image position on the intermediate transfer belt 3, a sheet of recording material is supplied from the sheet cassette 7 to the secondary transfer roller 6, the toner image is transferred onto the sheet, and a fixing device is provided. At 8, the toner image is fixed on the paper by heat and is discharged to the outside.

During this time, the inside of the apparatus is monitored by the sensor controller 18, and the CPU 14 controls the entire apparatus.

Next, the color shift in the embodiment of the present invention will be described.

When the image forming apparatus performs the printing operation,
The temperature inside the apparatus rises due to the operation of the fixing device 8 and the motor, circuit, etc. (not shown) (in-machine temperature rise).

The method of raising the temperature in the machine depends on the installation environment of the device,
Depends on print speed, print interval, paper transport path, paper size, etc.

Color shift occurs due to the temperature rise inside the machine.

That is, in the color image forming apparatus having the configuration as shown in FIG. 1, the intermediate transfer belt 3 is warmed by the fixing device 8 and the intermediate transfer belt 3 is suspended, and the belt driving roller 4, the belt driven roller 5, The temperature of the secondary transfer roller 6 rises.

The surface of each roller is covered with a thin rubber layer, and the temperature of the roller increases the thickness of the rubber layer.

When the diameter of the belt driving roller 4 increases,
The speed of the intermediate transfer belt 3 increases and color misregistration occurs.

For example, when the distance between the Y photosensitive drum 1a and the Bk photosensitive drum 1d is 300 mm, a color shift of 300 mm * 2/10000 = 60 μm occurs with a velocity fluctuation of 0.02%.

Since the belt drive roller temperature sensor 12a detects the surface temperature of the belt drive roller 4, the temperature rises rapidly during the printing operation.

However, due to the heat capacity (thermal time constant) of the belt driving roller 4, when the temperature rises quickly, a time lag occurs before the color misregistration changes.

Similarly, at the optical section 2 and other locations that affect color misregistration variations, there is a time lag before the temperature rise and the color misregistration variations occur.

Next, the relationship between the detected temperature fluctuation amount and the color shift fluctuation amount will be described with reference to FIGS.

FIG. 3 shows a case where the temperature inside the machine rises due to the double-sided printing operation, FIG. 4 shows a case where the temperature inside the machine rises due to the single-sided printing operation, and FIG. 5 shows a case where the printer installation environment temperature rises while the printer is on standby. FIG. 6 shows a case where the temperature inside the machine is lowered after the temperature inside the machine is raised by the one-sided printing operation and then the printing is in standby.

Reference numerals 26a, 27a, 28a, and 29a show the relationship between the detected temperature fluctuation amount of the belt drive roller temperature sensor 12a and the color shift fluctuation amount, which are 26b, 27b, 28b, and 29b.
Indicates the relationship between the detected temperature variation of the environment sensor 13a and the color shift variation, and 26c, 27c, 28c, and 29c indicate the relationship between the difference between the temperature detected by the belt drive roller temperature sensor 12a and the environment sensor 13a and the color shift variation. Indicates.

Δcpr is the allowable amount of color misregistration variation, Δt
a1, Δta2, Δta3, and Δta4 are temperature fluctuation amounts of the belt drive roller temperature sensor 12a when the color misregistration fluctuation amount is Δcpr, and tc1, tc2, tc3, and tc4 are belt drive roller temperature sensors when the color misregistration fluctuation amount is Δcpr. 12
temperature difference between a and the environmental sensor 13a (not the amount of fluctuation), t
1 (0) indicates the temperature detected by the belt drive roller temperature sensor 12a when the color misregistration correction is executed.

The color misregistration variation amount in each figure shows a total of various color misregistration factors.

The variation of the color misregistration amount mainly occurs due to the temperature variation.

Since the variation amount and the variation direction are not constant for each of various color shift factors, the relationship between the temperature variation amount and the color shift variation amount is not necessarily linear as shown in FIGS.

However, the present invention can be applied regardless of whether it is linear or not. Therefore, in this embodiment, the case where the relationship between the temperature variation and the color misregistration variation is linear will be described.

First, the case of single-sided printing will be described with reference to FIG.

In the case of single-sided printing, the temperature rises quickly and a time lag occurs before the color misregistration changes.

Therefore, the amount of temperature change with respect to the amount of color shift change becomes large (27a).

On the other hand, the environment sensor 13a includes an intermediate transfer belt 3, an optical section 2, a drive section having a motor (not shown), and the like.
Also, since the temperature rises slowly during the printing operation apart from the circuit portion, the temperature variation amount with respect to the color misregistration variation amount becomes small (27b).

Therefore, during the printing operation, the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a becomes large (27c).

Next, the case of double-sided printing will be described with reference to FIG.

For double-sided printing, the secondary transfer roller 6
Since the intermediate transfer belt 3 directly contacts the warmed sheet that has passed through the fixing device 8 and is warmed, the temperature of the belt driving roller 4 is further increased.

Further, since the paper warmed after passing through the fixing device 8 is conveyed inside the machine again, the entire machine is warmed, so that the temperature rise around the environment sensor 13a is also faster than in the case of single-sided printing.

Therefore, the temperature fluctuation amount between the belt drive roller temperature sensor 12a and the environment sensor 13a and the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a with respect to the color misregistration fluctuation amount are larger than in the case of one side ( 26a, 26b, 26c).

Next, a case where the printer installation environment temperature rises while the printer is on standby will be described with reference to FIG.

If the printer installation environment temperature rises while the printer is on standby, the temperature rise will be slower than during the printing operation.

There is little time lag between the temperature rise and the color shift variation due to the deformation of the members, the temperature variation amount is small relative to the color shift variation amount, and the intermediate transfer belt 3 is not operating. Roller temperature sensor 12
There is almost no temperature difference between a and the environment sensor 13a, and the temperatures detected by the belt drive roller temperature sensor 12a and the environment sensor 13a vary similarly (28a, 28b, 28).
c).

Next, with reference to FIG. 6, a case will be described in which, after the temperature inside the machine is raised by the printing operation, the printing is in standby and the temperature inside the machine falls.

After the temperature inside the machine has risen due to the printing operation, when the printing is on standby and the temperature inside the machine falls, the temperature fluctuation (falling) is fast, similar to the temperature rise inside the machine due to the printing operation.
Belt drive roller temperature sensor 1 for color shift variation
2a and the environmental sensor 13a have large temperature fluctuations (2
9a, 29b).

On the other hand, the belt drive roller temperature sensor 12a
Temperature difference between the environment sensor 13a and the environment sensor 13a gradually decreases (29
c).

When the printer installation environment temperature drops while the printer is on standby, there is almost no temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a as in the case where the printer installation environment temperature rises, and the belt drive roller temperature sensor 12a.
And the temperature detected by the environment sensor 13a similarly changes (not shown).

Further, the relationship between the temperature variation amount and the color misregistration variation amount varies depending on the same single-sided printing or the installation environment of the apparatus.

For example, when the apparatus installation environment temperature is high (high temperature environment), the temperature inside the apparatus is high at the start of the printing operation, so the temperature rise inside the machine is small (slow) and the apparatus installation environment temperature is low (low temperature environment). Indicates that the temperature inside the machine is large (fast) because the temperature of the device at the start of the printing operation is low.

Further, under the same conditions except the environment temperature set by the apparatus, the behavior as shown in FIG. 4 is exhibited in the high temperature environment, and the behavior as shown in FIG. 3 is exhibited in the low temperature environment.

In this way, the allowable amount of color misregistration variation Δcp
The temperature fluctuation amount (Δta1 to Δta4) with respect to r differs depending on the conditions and the environment.

Therefore, the temperature fluctuation amount (Δta1 to Δta)
It is necessary to determine the color misregistration correction timing using not only 4) but also the temperature difference (tc1 to tc4).

A flowchart for this is shown in FIG.

FIG. 7 is a diagram for explaining the determination of the color misregistration correction timing according to the first embodiment of the present invention.

T1 is the belt drive roller temperature sensor 12
The detected temperature of a, t2 is the detected temperature of the environment sensor 13a,
t1 (0) is the temperature detected by the belt drive roller temperature sensor 12a when the color misregistration correction is executed and is held in the memory 16.

REF3 is a threshold value for discriminating the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a, and REF1 is the belt drive roller temperature sensor 12a.
And the environment sensor 13a have a small temperature difference (less than a threshold value), the first threshold value REF2 for discriminating the magnitude of the temperature fluctuation of the belt drive roller temperature sensor 12a is REF2, which is the belt drive roller temperature sensor 12a and the environment sensor 13a. Belt drive roller temperature sensor 1 when the temperature difference between and is large (above a threshold value)
The 2nd threshold value which distinguishes the magnitude of the temperature fluctuation of 2a is shown.

As the second threshold value, a value larger than the first threshold value is set.

The CPU 14 detects the temperature and determines the threshold value.
Is executed via the sensor control unit 18.

When the color misregistration correction operation is executed, the detected temperature t1 (0) of the belt drive roller temperature sensor 12a is stored in the memory 16
Hold on.

After that, the belt drive roller temperature sensor 12
The detected temperature t1 of a is sequentially detected to detect the first threshold value REF1 and the belt drive roller temperature sensor 1 after the color misregistration correction operation is executed.
The temperature fluctuation amount t1-t1 (0) of 2a is compared and determined.

When t1-t1 (0) exceeds ± REF1, it is determined whether the temperature difference t1-t2 between the belt drive roller temperature sensor 12a and the environmental sensor 13a exceeds the threshold value REF3.

When the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a is less than or equal to the threshold value REF3, it is determined that the temperature rise is slow and the temperature variation amount is small with respect to the color misregistration variation amount, and the color misregistration correction operation is performed. Run.

When the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a exceeds the threshold value REF3, it is determined that the temperature rises quickly and the temperature variation amount is large relative to the color misregistration variation amount, and the color misregistration correction is performed. No action is taken.

Continuing, the belt drive roller temperature sensor 12
The detection temperature t1 of a is sequentially detected.

Furthermore, temperature fluctuations inside the machine continue, and t1-
When t1 (0) exceeds ± REF2, the color misregistration correction operation is executed.

In this way, the detected temperature fluctuation amount t1-t1
By determining the color misregistration correction timing using not only (0) but also the detected temperature difference t1-t2, the color misregistration correction operation can be executed at an appropriate timing.

Although the detected temperature fluctuation amount is obtained from the detected temperature t1 of the belt driving roller temperature sensor 12a here, it is calculated from the detected temperature t2 of the environment sensor 13a, or
It may be obtained from both the temperature t1 detected by the belt drive roller temperature sensor 12a and the temperature t2 detected by the environment sensor 13a.

Since the specific contents of the color misregistration correction operation after the color misregistration correction timing is determined are the same as those in the conventional technique, the description thereof will be omitted.

(Second Embodiment) Next, a second embodiment will be described with reference to FIGS. 8 and 9.

Only the points different from the first embodiment will be described.

FIG. 8 is a block diagram of the first embodiment shown in FIGS.
Similarly, it is a diagram illustrating a relationship between a temperature variation amount and a color shift variation amount.

After the temperature inside the machine is raised by the printing operation, the printing operation is continued and the belt drive roller temperature sensor 12a
And the temperature difference between the environment sensor 13a and the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a are small (slow).

30a is a belt drive roller temperature sensor 1
The relationship between the detected temperature fluctuation amount and the color shift fluctuation amount of 2a is
Is the relationship between the temperature variation amount detected by the environment sensor 13a and the color misregistration variation amount, and 30c is the belt drive roller temperature sensor 12
The relationship between the difference between the temperature detected by a and the environment sensor 13a and the amount of color misregistration variation is shown.

Δcpr is a permissible amount of color misregistration variation, Δta
5 is the temperature variation detected by the belt drive roller temperature sensor 12a when the color misregistration variation is Δcpr, and tc5 is the belt drive roller temperature sensor 12a when the color misregistration variation is Δcpr.
And the temperature difference between the environment sensor 13a (not the amount of fluctuation), tc
(0) is the detected temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a when the color misregistration variation amount is t1 (0), and Δtc5 is the detected temperature difference tc5 and the detected temperature difference tc.
The amount of fluctuation in temperature difference from (0) is shown.

In the case of FIG. 8, the detected temperature fluctuation amount between the belt drive roller temperature sensor 12a and the environment sensor 13a is small (slow) (30a, 30b), and the detected temperature difference tc5 between the belt drive roller temperature sensor 12a and the environment sensor 13a is: large.

However, the temperature difference variation amount Δtc5 is small (slow).

In such a case, rather than using the detected temperature variation Δta5 and the temperature difference tc5 as in the first embodiment, the detected temperature variation Δta5 and the temperature difference variation Δtc are used.
5 and 5, it is possible to determine an appropriate color shift correction timing.

Therefore, in the second embodiment, instead of the detected temperature difference tc5 used in the first embodiment, the temperature difference variation amount Δ
Using tc5, the color misregistration correction timing is determined based on the detected temperature fluctuation amount Δta5 and the temperature difference fluctuation amount Δtc5.

FIG. 9 is a diagram for explaining the determination of the color misregistration correction timing according to the second embodiment.

Instead of the threshold value REF3 (FIG. 7) for discriminating the magnitude of the temperature difference (not the variation amount) between the belt drive roller temperature sensor 12a and the environment sensor 13a in the first embodiment, the belt drive roller temperature sensor is used. Threshold value RE for discriminating the magnitude of variation in temperature difference between 12a and environment sensor 13a
Use F4.

When the color misregistration correction operation is executed, the temperature t2 (0) detected by the environment sensor 13a is held in the memory 16 together with the temperature t1 (0) detected by the belt drive roller temperature sensor 12a.

Thereafter, the belt drive roller temperature sensor 12
The detected temperature t1 of a is sequentially detected to detect the first threshold value REF1 and the belt drive roller temperature sensor 1 after the color misregistration correction operation is executed.
The detected temperature fluctuation amount t1−t1 (0) of 2a is compared and determined.

When t1-t1 (0) exceeds ± REF1, the variation amount (t1-t2)-(t1) of the temperature difference between the belt drive roller temperature sensor 12a and the environmental sensor 13a.
It is determined whether or not (0) -t2 (0) exceeds the threshold value REF4.

When the variation amount of the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a is less than or equal to the threshold value REF4, it is determined that the temperature rise is slow and the detected temperature variation amount with respect to the color misregistration variation amount is small, and the color misregistration is caused. Execute the correction operation.

If the temperature difference variation amount between the belt drive roller temperature sensor 12a and the environment sensor 13a exceeds the threshold value REF4, it is determined that the temperature rises quickly and the detected temperature variation amount with respect to the color misregistration variation amount is large. The color misregistration correction operation is not executed.

Continuing, the belt drive roller temperature sensor 12
The detection temperature t1 of a is sequentially detected.

Furthermore, temperature fluctuations inside the machine continue, and t1-
When t1 (0) exceeds ± REF2, the color misregistration correction operation is executed.

In this way, the detected temperature fluctuation amount t1-t1
Not only (0) but also the temperature difference fluctuation amount (t1-t2)-(t1
By determining the color misregistration correction timing using (0) -t2 (0), the color misregistration correction operation can always be executed at an appropriate timing.

Further, as a matter of course, even in the case described in the first embodiment, the color misregistration correction operation can be executed at an appropriate timing.

That is, as shown in FIG. 5, when the temperature variation between the belt drive roller temperature sensor 12a and the environment sensor 13a is small (slow), the variation amount of the temperature difference between the belt drive roller temperature sensor 12a and the environment sensor 13a. Is also small.

Then, as shown in FIGS. 3, 4, and 6, when the temperature fluctuations of the belt drive roller temperature sensor 12a and the environment sensor 13a are large (fast), the temperatures of the belt drive roller temperature sensor 12a and the environment sensor 13a are increased. The amount of change in the difference is large.

As described in the first embodiment, the detected temperature fluctuation amount is calculated from the detected temperature t2 of the environment sensor 13a, or the detected temperature t1 of the belt drive roller temperature sensor 12a and the detected temperature of the environment sensor 13a. You may obtain | require from both t2.

(Third Embodiment) Next, referring to FIG.
A third embodiment will be described.

Only the points different from the first and second embodiments will be described.

FIG. 10 is a diagram for explaining the entire image forming apparatus according to the third embodiment of the present invention.

Instead of the belt drive roller temperature sensor 12a and the environment sensor 13a of the first and second embodiments, the optical section temperature sensor 1 for detecting the ambient temperature of the optical section 2 is used.
2b and an environment sensor 13b (different from 13a) that detects the temperature in the vicinity of the paper cassette 7.

The temperature rise around the optical section 2 is large (fast) during the printing operation due to the driving operation of the laser, polygon motor, etc. not shown.

Further, when optical components such as lenses (not shown) of the optical section 2 are deformed due to the temperature rise, the photosensitive drums 1a to 1d.
The laser irradiation position of changes, and a color shift occurs.

Therefore, the optical section temperature sensor 12b has the first
And the belt drive roller temperature sensor 12a of the second embodiment.
It has the same function as.

On the other hand, the vicinity of the paper cassette 7 is in a position where it is unlikely to be affected by the temperature rise inside the machine due to the printing operation, and the temperature rise during the printing operation is small (slow).

Therefore, the environment sensor 13b has the same function as the environment sensor 13a of the first and second embodiments.

Optical part temperature sensor 12b and environment sensor 13
Using b, the same operation as in the first or second embodiment is executed.

The temperature sensors in the machine are not limited to these positions.

The color shift correction execution timing based on the detected temperature difference of the two temperature sensors or the detected temperature difference variation amount is not limited to the comparison and determination means described in the above embodiment.

For example, the detected temperature fluctuation amount and the detected temperature difference or the detected temperature difference fluctuation amount may be divided into a plurality of levels to hold the table value.

Further, the timing of executing the color misregistration correction based on the temperature variation detected by the temperature sensor is not limited to the comparison / determination means described in the above embodiment.

For example, when the detected temperature difference or the detected temperature difference fluctuation amount is large, the color misregistration correction execution timing is determined according to the detected temperature fluctuation amount of one temperature sensor, and the detected temperature difference or the detected temperature difference fluctuation amount is determined. If is small, the color misregistration correction execution timing may be determined according to the detected temperature fluctuation amount of the other temperature sensor.

[0158]

As described above, according to the present invention,
Two temperature sensors are installed at locations where the temperature rise in the device is different, and the detected temperature fluctuation amount of one or both temperature sensors and the detected temperature difference between the two temperature sensors after the previous color misregistration correction operation is executed. Alternatively, when the next color misregistration correction operation execution timing is determined based on the variation of the detected temperature difference, the relationship between the temperature variation detected by the temperature sensor inside the apparatus and the color misregistration variation varies depending on various printing conditions. In addition, it is possible to provide a highly accurate color misregistration correction device that always performs color misregistration correction operation at appropriate timing without an unnecessary increase in downtime or an occurrence of color misregistration variation exceeding an allowable amount.

Further, according to the present invention, the detected temperature fluctuation amount of one or both of the temperature sensors is smaller than that when the detected temperature difference of the two temperature sensors or the detected temperature difference fluctuation amount is small, compared to the case where the detected temperature difference is large. Since the color misregistration correction is executed at the timing, there is no unnecessary downtime increase when the in-machine temperature rise is large (fast), and the amount of color misregistration variation exceeds the allowable amount when the in-machine temperature rise is small (slow). It is possible to provide a highly accurate color misregistration correction device that always executes color misregistration correction operations at appropriate timing without occurrence of the occurrence of color misregistration.

Furthermore, according to the present invention, since one temperature sensor is installed in the vicinity of a location where the temperature rise due to the printing operation is large (fast) and the color shift variation is large,
Based on the detected temperature fluctuation amount of one or both temperature sensors and the detected temperature difference between the two temperature sensors or the detected temperature difference fluctuation amount, the color misregistration correction operation execution timing can be detected more appropriately, and the color difference correction operation can always be performed at an appropriate timing. A highly accurate color misregistration correction device that executes a misregistration correction operation can be provided.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an entire image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating an entire control unit according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between a detected temperature fluctuation amount and a color misregistration fluctuation amount according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a relationship between a detected temperature fluctuation amount and a color shift fluctuation amount according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between a detected temperature fluctuation amount and a color misregistration fluctuation amount according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a relationship between a detected temperature fluctuation amount and a color shift fluctuation amount according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating determination of color misregistration correction timing according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating the relationship between the detected temperature fluctuation amount and the color misregistration fluctuation amount according to the second embodiment of the present invention.

FIG. 9 is a diagram illustrating determination of color misregistration correction timing according to the second embodiment of the present invention.

FIG. 10 is a diagram illustrating an entire image forming apparatus according to a third embodiment of the present invention.

FIG. 11 is a diagram illustrating various color shifts.

FIG. 12 is a diagram illustrating a color shift detection pattern.

[Explanation of symbols]

1a, 1b, 1c, 1d Photosensitive drums 2a, 2b, 2c, 2d Laser scanner 3 Intermediate transfer belt 4 Belt drive roller 6 Secondary transfer roller 7 Paper cassette 8 Fixer 9 Double-sided unit 11 Optical sensor 12a Belt drive roller temperature sensor 12b Optical part temperature sensor 13a, 13b Environment sensor 19a Driving means 20 Original image position 21a, 21b, 21c, 21d Image position 102a, 102b, 102c, 102d in case of color misregistration Image forming means 103a, 103b, 103c, 103d Transfer means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/14 G03G 21/00 372 F term (reference) 2H027 DA11 DA13 DA23 DA32 DE04 DE07 DE09 EA11 EB04 EC04 EC06 EC07 EC09 EC10 EC18 EC20 ED01 ED04 ED24 EE01 EE07 EF09 JA11 JB21 JC01 JC04 JC09 ZA07 2H030 AA01 AB02 AD17 AD18 BB02 BB16 BB41 BB42 2H200 FA01 FA04 FA16 GA12 GA23 GA29 GA30 GA34 GA40 GB22 GB25 HA02 HB12 HB22 JA02 JA29 JA30 JB06 JC03 JC19 JC20 PA10 PA12 PA15 PA18 PA19 PA24 PB15 PB16 PB20 PB27 PB38 PB40

Claims (4)

[Claims] 1. A plurality of image forming means each having an optical part and a latent image forming medium, an endless belt means successively passing through the plurality of image forming means, and the formed image, the endless belt means. A plurality of transfer means for transferring onto the recording material conveyed while being held on or on the endless belt means, a driving means for driving the endless belt means, and a color shift detection on the endless belt means Forming a pattern,
A color misregistration correction device for a color image forming apparatus, comprising: a color misregistration correction unit that electrically and mechanically corrects a color misregistration based on a detection result of the color misregistration detection pattern, wherein the image forming unit and the endless belt are provided. Means for detecting the temperature in the vicinity of one of the transfer means and the transfer means, and a second temperature detection means for detecting the temperature inside the color image forming apparatus in addition to the first temperature detection means. Means and an operation timing determining means for determining an operation timing of the color misregistration correcting means, wherein the operation timing determining means allows at least one of temperature fluctuation amounts detected by the first and second temperature detecting means. In addition, the operation timing is determined based on the detected temperature difference between the first and second temperature detection means or the variation amount of the detected temperature difference. Deviation correction device. 2. The operation timing determining means includes the first and second temperature detecting means when the difference between the detected temperatures or the variation in the detected temperature difference is smaller than when the difference is large.
Alternatively, the color misregistration correction device of the color image forming apparatus according to claim 1, wherein the color misregistration correction device is operated at a timing when the detected temperature fluctuation amount of the second temperature detection device is small. 3. The color image forming apparatus according to claim 1, wherein the first temperature detecting unit detects a surface temperature of a belt driving roller on which the endless belt unit is suspended. Deviation correction device. 4. The color misregistration correction device for a color image forming apparatus according to claim 1, wherein the first temperature detection unit detects an ambient temperature of the optical unit.