JPH10213943A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately correct register deviation due to a change in ambient temperature without reducing the productivity in forming an image by controlling plural image output parts based on the register deviation correction valve which corresponds to the detected ambient temperature. SOLUTION: When a power is supplied and register checking command is given by a control part 15, a pattern signal for detecting the register deviation is generated by a pattern generator 16, and respective image output parts 5 to 8 are operated by the image control part 17 based on the pattern signal. Thus, the register deviation detecting pattern is formed all over an intermediate transfer belt 1, then, the pattern image is read by the register sensor 13. At this time, the register deviation correction value is calculated by a calculation part 18 based on the reading result of the register sensor 13, the calculated register deviation correction value is stored by a memory 19 so as to correspond to the ambient temperature detected by a temperature sensor 14 at the time of checking the register. And the register alignment is performed based on the register deviation correction value stored by memory 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which a plurality of image output units are arranged along an image carrier so that a multicolor image can be formed.

[0002]

2. Description of the Related Art FIG. 8 is a schematic diagram showing an example of this type of image forming apparatus. In FIG. 8, an intermediate transfer belt 1 serving as an image carrier includes a driving roll 2 and driven rolls 3 and 3.
And a pair of transfer rolls 4 is stretched in a loop shape. The intermediate transfer belt 1 travels in the direction of the arrow in FIG.
A plurality (four) of image output units 5 to 8 are arranged along the intermediate transfer belt 1 between the driving roll 2 and the driven roll 3. These image output units 5 to 8 are provided with black (K) from upstream to downstream in the belt running direction.
, Yellow (Y), magenta (M), and cyan (C). Each of the image output units 5 to 8 includes laser writing units 5a to 8a, photosensitive drums 5b to 8b, and peripheral devices (e.g., a charger, a developing device, a transfer device, and a cleaner).

In the image forming apparatus having the above structure, the photosensitive drums 5b to 8b are controlled by the laser writing units 5a to 8a.
The electrostatic latent image written on the surface b is developed as a toner image, and the toner image is transferred onto the intermediate transfer belt 1. At this time, each image output unit 5 is provided on the intermediate transfer belt 1.
The images of different colors (black → yellow → magenta → cyan) are sequentially transferred in a superimposed manner, thereby forming one multicolor image (color image). further,
The multi-color image formed on the intermediate transfer belt 1 is collectively transferred to a sheet 10 sent from a sheet tray 9 to a transfer roll 4, and then the sheet 10 is image-fixed by a fixing device 11 and discharged outside the apparatus. Is done. Further, the residual toner remaining on the intermediate transfer belt 1 after the image is transferred to the paper 10 is removed by a cleaner 12 disposed near the driving roll 2.

By the way, in this type of image forming apparatus, one multi-color image is formed by sequentially superimposing images of different colors on the intermediate transfer belt 1 serving as an image carrier. When the transfer position of the image with respect to the intermediate transfer belt 1 is relatively shifted in 8, a color registration shift (registration shift) occurs, and as a result, the quality of the output image is reduced.

Therefore, generally, registration misalignment is corrected by performing registration based on the following registration control technique. That is, a registration misregistration detection pattern is formed on the intermediate transfer belt 1, and the registration misregistration detection pattern is
And the like. At this time, it is detected how much the pattern position read by the registration sensor 13 deviates from the regular position (register check), and
For example, the laser writing units 5a-8
Registration adjustment such as adjusting the writing timing of a, the frequency of the image clock, and the rotation phase of the polygon mirror is performed.

[0006]

However, in the related art, even when the above-described registration is performed, the environmental temperature inside the apparatus gradually increases during the image formation, so that, for example, the mechanical parts may be damaged. There has been a problem that the dimensions and the mounting position are changed, which causes a new registration deviation.

Therefore, as a technique for correcting a change in environmental temperature, for example, Japanese Patent Application Laid-Open No. 1-142676 (hereinafter referred to as Conventional Example 1) discloses that a change in environmental temperature accompanying image formation is detected by a temperature sensor. There is disclosed a technique in which a register check is performed when an environmental temperature detected by a sensor deviates from a predetermined allowable range. Further, Japanese Unexamined Patent Publication No.
Japanese Patent Publication No. 188697 (Conventional Example 2) discloses a technique in which an integrated time after power-on is measured and a registration check is performed according to the integrated time. Further, Japanese Patent Application Laid-Open No. 1-96665 (Prior Art 3) discloses that a temperature sensor detects a change in environmental temperature accompanying image formation, and starts writing of a laser writing unit based on the environmental temperature detected by the temperature sensor. A technique for controlling the timing is disclosed.

However, in the case of the above-mentioned conventional examples 1 and 2, a normal image forming process must be interrupted when performing a registration check. In addition, in order to always obtain a high-quality image without color misregistration, it is necessary to frequently perform registration with respect to a change in environmental temperature or an integrated time after power-on.
As a result, there has been a problem that productivity of image formation is further reduced. On the other hand, in the case of the above-mentioned conventional example 3, the image writing start timing is simply controlled in accordance with the change in the environmental temperature. Could not be corrected. In addition, since the amount of registration error due to a change in environmental temperature is slightly different in each image forming apparatus, it is not possible to correct even the registration error unique to the image forming apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to accurately correct a registration error caused by a change in environmental temperature without lowering the productivity of image formation. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and a plurality of image output units are arranged along an image carrier, and a plurality of image output units are provided on the image carrier. In an image forming apparatus capable of forming a multi-color image by sequentially superimposing images of different colors depending on the image forming unit, a plurality of image output units based on a reading result of a registration misregistration detection pattern formed on an image carrier. Calculating means for calculating a shift correction value;
A temperature detecting means for detecting an environmental temperature inside the apparatus in which a plurality of image output units are provided; and a register calculated by the calculating means and the environmental temperature detected by the temperature detecting means when forming a registration deviation detecting pattern. A storage unit for storing the shift correction value in association with the register unit, and a registration shift correction value corresponding to the environmental temperature detected by the temperature detection unit when the image is formed by the plurality of image output units, and the readout thereof. And control means for controlling the plurality of image output units based on the registration error correction value.

In the image forming apparatus having the above configuration, when forming the registration shift detection pattern, the environmental temperature detected by the temperature detection means and the registration shift correction value calculated by the calculation means are associated with each other in the storage means. Remember,
Thereafter, when performing image formation by the plurality of image output units, the control unit reads a registration deviation correction value corresponding to the environmental temperature detected by the temperature detection unit from the storage unit, and based on the read registration deviation correction value. Registration is performed by controlling a plurality of image output units. Accordingly, even when the environmental temperature inside the apparatus changes during image formation, it is not necessary to form a registration deviation detection pattern and calculate a registration deviation correction value each time, so that image formation is not interrupted. High-accuracy registration can be performed.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention.
In FIG. 1, reference numeral 1 denotes an intermediate transfer belt serving as an image carrier, 2 denotes a driving roll, 3 denotes a driven roll, 4 denotes a transfer roll, 5 to 8 denote an image output unit, 11 denotes a fixing device, 12 denotes a cleaner, and 13 denotes a cleaner. This is a registration sensor, and these components are the same as those shown in FIG. However, in the present embodiment, a temperature sensor 14 is provided as temperature detecting means for detecting the environmental temperature inside the apparatus in which the plurality of image output units 5 to 8 are provided.

The control system includes a control unit 15
And a pattern generator 16, an image control unit 17, a calculation unit 18, and a memory 19. The pattern generator 16 generates a pattern signal of a registration error detection pattern when the control unit 15 instructs a registration check. The image control unit 17 operates each of the image output units 5 to 8 on the basis of an image signal to be transferred to a sheet or a pattern signal generated by the pattern generator 16, and receives a registration check instruction from the control unit 15. And each image output unit 5 based on the pattern signal generated by the pattern generator 16.
8 are operated to form a registration deviation detection pattern (toner image) corresponding to the pattern signal on the intermediate transfer belt 1.

At this time, for example, as shown in FIG. 2, a registration misregistration detecting pattern P is formed on both ends (IN / OUT) of the intermediate transfer belt 1 in a predetermined shape. By reading P with the pair of registration sensors 13, it is possible to detect a tilt shift (skew) of each color in the oblique direction, a magnification shift in the main scanning direction, and the like. At this time, a registration misregistration detection pattern is also added to the intermediate position of the intermediate transfer belt 1 in the width direction, and the pattern is read by a separate registration sensor. Can also be detected.

The arithmetic unit 18 is provided with a plurality of image output units 5 to 5
When a registration error detection pattern formed on the intermediate transfer belt 1 by the registration sensor 13 is read by the registration sensor 13, a registration error correction value is calculated based on the read result. Here, the types of the registration deviation include a deviation (X margin) in the main scanning direction X corresponding to the width direction of the intermediate transfer belt 1 and a sub-scanning corresponding to the running direction of the intermediate transfer belt 1 as shown in FIG. FIG. 4 shows the displacement in the direction Y (Y margin).
(A) As shown in FIG.
Further, there is a magnification shift in the main scanning direction X as shown in FIG. For this reason, the calculation unit 18 calculates a registration shift correction value for each type of the registration shift described above. The memory 19 calculates the environmental temperature detected by the temperature sensor 14 and the calculation unit 18 when a registration check instruction is issued from the control unit 15 and a registration misregistration detection pattern is thus formed on the intermediate transfer belt 1. The stored misregistration correction values are stored in association with each other, and the specific storage format will be described in detail later.

Next, the operation of the image forming apparatus having the above configuration will be described. First, when the apparatus power is turned on at the start of use of the image forming apparatus, the control unit 15 issues a registration check instruction. As a result, a pattern signal of the registration misregistration detection pattern is generated from the pattern generator 16, and based on the pattern signal, the image control unit 17 operates each of the image output units 5 to 8. As a result, a registration misregistration detection pattern is formed over the entire circumference of the intermediate transfer belt 1, and the pattern image is read by the registration sensor 13.

At this time, the arithmetic unit 18 controls the registration sensor 13
, A registration deviation correction value is calculated based on the reading result. Here, a main factor common to the various types of registration misalignment described above is the positional accuracy of each image output unit (laser writing unit, photosensitive drum and its peripheral devices) 5 to 8.
Therefore, registration deviation amounts of the various is changed, yet the degree of change as the ambient temperature inside the apparatus as shown in FIG. 5 (a) _{T 0 → T 1 → T 2} → ... and rises, 5
As shown in (b), the color is different for each color (K, Y, M, C), that is, for each of the image output units 5 to 8.

The arithmetic unit 18 calculates a registration error correction value for each color (K, Y, M, C) corresponding to each of the image output units 5 to 8 based on the reading result of the registration sensor 13. At the same time, a registration shift correction value is calculated for each of the X margin, the Y margin, the skew, and the magnification shift in accordance with the type of the above-described registration shift.

The registration deviation correction value calculated by the arithmetic unit 18 is stored in the memory 19 in association with the environmental temperature detected by the temperature sensor 14 at the time of the registration check.
Specifically, as shown in FIG. 6A, in the memory 19, when the environmental temperature at the time of the register check is T ₀ ,
The misregistration correction values for each color (K, Y, M, C) corresponding to the environmental temperature are stored in the form of a table divided into various misregistrations (X margin, Y margin, skew, magnification shift).

Thereafter, when normal image formation is continuously performed, the environmental temperature inside the apparatus gradually increases. At that time, the control unit 15 monitors the environmental temperature inside the apparatus via the temperature sensor 14, and when the environmental temperature detected by the temperature sensor 14 reaches T ₁ , gives the register check instruction again.
As a result, a registration deviation correction value corresponding to the environmental temperature T ₁ is obtained by the same processing as described above, and the data is newly stored in the memory 19. While repeating such a series of processing, the memory 19 stores a predetermined temperature increment (for example, 2
The registration deviation correction values corresponding to the respective environmental temperatures are sequentially stored. Then, if the environmental temperature at the time of completion of the image forming was T _m, environmental temperature T _0, T _1, T ₂ as shown in FIG. 6 (b), ..., misregistration correction corresponding to T _m The value is stored in the memory 19.

Thus, the environmental temperatures T ₀ , T ₁ , T ₂ ,
..., the misregistration correction value corresponding to the T _m is stored in the memory 19, thereafter, to start image formation, the environmental temperature is above that is detected by the temperature sensor 14 in the image forming T _0, T ₁ , T ₂ ,..., T _m , registration is performed based on the registration deviation correction value stored in the memory 19. For example, when the environmental temperature detected by the temperature sensor 14 has reached T ₂ , the control unit 15 reads a registration deviation correction value corresponding to the environmental temperature T ₂ from the memory 19, and based on the read registration deviation correction value. The registration is performed by controlling the image output units 5 to 8.

Furthermore, since the image formation was continued for a long time, when the environmental temperature sensed by the temperature sensor 14 reaches T _n exceeds the above T _m, the instruction of the control section 15 cashier checks again give. Then, add the misregistration correction value corresponding to the environmental temperature T _n at that time in the memory 19. Reinstruction such cashier checks, environmental temperature at the time of image formation start is performed similarly to the case of below the T _0. As a result, the environmental temperature stored in the memory 19 gradually increases over a wide range.
The environmental temperature detected by the temperature sensor 14 during image formation is
The temperature does not deviate from the range of the environmental temperature stored in the memory 19. Therefore, even when the environmental temperature inside the apparatus changes during image formation, registration can be performed with high accuracy based on the registration deviation correction value in the memory 19 without performing a registration check each time. Further, since the data stored in the memory 19 is based on the registration check in each image forming apparatus, it is possible to correct the registration deviation unique to the apparatus.

By the way, the various types of registration deviation amounts described above are:
Device internal ambient temperature changes a little even during changes from T ₀ to T _1. Therefore, the finer the temperature step of the environmental temperature stored in the memory 19, the more accurate the correction.
However, if the temperature step is set extremely finely, a large-capacity memory 19 is required, and the register check must be performed frequently until data is sufficiently accumulated in the memory 19. Disappears. For example, when the temperature step in the memory 19 is set to 2 ° C., and when the temperature step is set to 1 ° C. which is finer than that, the number of registration checks is doubled.

Therefore, in this embodiment, the memory 19
The blank temperature between each environmental temperature stored in, for example, FIG.
In the correction table of (b), assuming that T ₀ is 20 ° C. and T ₁ is 22 ° C., the registration deviation correction value corresponding to the blank temperature 21 ° C. during that period is changed to the registration deviation correction value corresponding to the surrounding environmental temperature. The values, that is, the registration deviation correction values corresponding to T ₀ and T ₁ are complemented.

As a specific complementing method, for example, T
₀ = R ₀ , T ₁ = 20 ° C.
If the registration error correction value corresponding to = 22 ° C. is “R ₁ ”, the registration error correction value “R” corresponding to the blank temperature of 21 ° C. during that time may be obtained by the following equation. R = (R ₀ + R ₁ ) ÷ 2, or R = (R ₁ -R ₀ ) ÷ 2
+ R ₀

By complementing the registration error correction corresponding to the blank temperature between the respective environmental temperatures in this manner, a registration error correction value corresponding to the blank temperature can be obtained without actually performing a registration check. . Accordingly, when the environmental temperature detected by the temperature sensor 14 reaches the blank temperature, the image output units 5 to 8 are controlled based on the registration error correction values complemented as described above, so that the registration check is performed. This makes it possible to perform registration with higher accuracy without causing a reduction in efficiency.

Here, as shown in FIG.
Environmental temperature (T₀, T₁, T _Two, ...)
If the deviation change amount is “G”, the blank temperature during that
By complementing the corresponding misregistration correction value,
The amount of change in registration deviation decreases by α and becomes “g”. this
Therefore, each environmental temperature (T₀,
T ₁, T_Two,…), Set the blank temperature more finely,
Compensate the misregistration correction value corresponding to each blank temperature.
By doing so, the amount of registration deviation change between each temperature is
Thus, the registration accuracy can be improved.

Therefore, when the blank temperature between the environmental temperatures in the memory 19 is set more finely, for example, T ₀ = 20 ° C.
When T ₁ = 22 ° C., the blank temperature during that period is 0.5
In the case of dividing into 20.5 ° C., 21 ° C., and 21.5 ° C. in increments of ° C., a registration misregistration detection pattern corresponding to each blank temperature may be obtained as follows. First, a registration shift correction value “R” corresponding to a blank temperature of 21 ° C. is obtained according to the above equation. Further, by using the registration deviation correction value R, 20.
A registration error correction value “Ra” corresponding to 5 ° C. and a registration error correction value “Rb” corresponding to 21.5 ° C. are obtained by the following equations. Ra = (R ₀ + R) ÷ 2, or Ra = (R−R ₀ ) ÷ 2
+ R ₀ Rb = (R + R ₁ ) ÷ 2 or Rb = (R ₁ -R) ÷ 2
+ R

On the other hand, when the image forming apparatus is used for a long period of time, registration misalignment may occur due to wear or positional fluctuation of each part. In such a case, the misregistration correction value calculated by the calculation unit 18 corresponding to the environmental temperature detected by the temperature sensor 14 and the misregistration correction value previously stored in the memory 19 in association with the same environmental temperature are used. Error occurs.

As a countermeasure, for example, a registration check is performed only once each time the apparatus power is turned on, and a registration deviation correction value corresponding to the environmental temperature detected by the temperature sensor 14 at that time is calculated by the calculation unit 18. as well as operation in a result of the calculation (misregistration correction value), the error between the misregistration correction values stored in the memory 19, various misregistration and [Delta] K _1, for example, in each color, [Delta] Y _1, ..., [Delta] C ₄ Ask like.
Then, the registration error correction value corresponding to each environmental temperature stored in the memory 19 is corrected by the error obtained as described above, and registration is performed based on the corrected registration error correction value. As a result, even when the positional accuracy or the like of each part is degraded over time, it is possible to accurately correct the registration deviation due to the environmental temperature change over a long period of time.

In the above-described embodiment, the image forming apparatus for forming the registration deviation detecting pattern on the intermediate transfer belt 1 has been described. However, the present invention is not limited to this. The present invention can be similarly applied to an image forming apparatus that forms a registration shift detection pattern by superimposing an image on a sheet, or an image formation apparatus that forms a registration shift detection pattern on a sheet conveying belt or a sheet on the belt.

[0032]

As described above, according to the image forming apparatus of the present invention, at the time of forming the registration error detection pattern, the environmental temperature detected by the temperature detection means and the registration error correction value calculated by the calculation means are used. Are stored in the storage unit in association with each other, and when performing image formation by the plurality of image output units, the registration deviation correction value corresponding to the environmental temperature detected by the temperature detection unit is read from the storage unit, Since the plurality of image output units are controlled based on the read registration deviation correction value, even if the environmental temperature inside the apparatus changes during image formation, high-precision registration can be performed without interrupting image formation. Can be performed.
As a result, it is possible to highly accurately correct a registration deviation due to a change in environmental temperature without lowering the productivity of image formation, so that a high-quality output image can always be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of pattern formation.

FIG. 3 is a diagram (part 1) for explaining types of misregistration;

FIG. 4 is a diagram (part 2) for explaining types of misregistration;

FIG. 5 is a diagram illustrating registration deviation variation characteristics.

FIG. 6 is a diagram illustrating a data storage format.

FIG. 7 is a diagram for explaining a difference in a registration deviation change amount due to a temperature step.

FIG. 8 is a schematic configuration diagram illustrating an example of an image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 intermediate transfer belt (image carrier) 5 to 8 image output unit 13 registration sensor 14 temperature sensor (temperature detection unit) 15 control unit (control unit) 18 operation unit (operation unit) 19 memory (storage unit)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiki Matsuzaki 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. In-house (72) Inventor Kenta Ogata 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd.

Claims (3)

[Claims] A plurality of image output units are arranged along an image carrier, and images of different colors can be sequentially superimposed on the image carrier by the plurality of image output units to form a multicolor image. Computing means for calculating a registration error correction value based on a reading result of a registration error detection pattern formed on the image carrier by the plurality of image output units; and the plurality of image output units. Temperature detecting means for detecting an environmental temperature inside the apparatus provided with the image forming apparatus; and, at the time of forming the registration error detection pattern, correcting the environment temperature detected by the temperature detection means and the registration error calculated by the calculation means. Storage means for storing values in association with each other, and when performing image formation by the plurality of image output units,
A control unit for reading a registration shift correction value corresponding to the environmental temperature detected by the temperature detection unit from the storage unit, and controlling the plurality of image output units based on the read registration shift correction value. An image forming apparatus comprising: 2. The method according to claim 1, wherein a registration error correction value corresponding to a blank temperature between respective environmental temperatures stored in said storage means is complemented based on registration error correction values corresponding to environmental temperatures before and after the blank temperature. The image forming apparatus according to claim 1. 3. A registration error correction value calculated by the arithmetic processing corresponding to the environmental temperature detected by the temperature detecting means, and a registration error correction value stored in the storage means in association with the same environmental temperature before that. 2. The image forming apparatus according to claim 1, wherein when an error occurs with the shift correction value, the registration shift correction value stored in the storage unit is corrected by the error.