JP2003223034A - Image forming apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the lowering of accuracy in color shift detection and color shift correction and also to restrain the actual color shift of an image in an image forming apparatus where a plurality of color toner images obtained by developing a latent image formed on an image carrier are superposed and recorded on a circularly moving intermediate transfer body or a recording medium carried by a carrying belt. <P>SOLUTION: In a printer 10, an image forming control part 11 controlling image forming operation is informed of the correction information on the speed of the carrying belt from a driving control part 14 having a color shift correction means and a speed correction means for the carrying belt, and also the control part 14 decides whether or not the speed of the carrying belt is corrected according to designation from the control part 11. The color shift is corrected after performing the speed adjustment of the carrying belt and then inhibiting the speed adjustment. <P>COPYRIGHT: (C)2003,JPO

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 such as a printer, for example, an electrophotographic image forming apparatus and a control method thereof.

[0002]

2. Description of the Related Art FIG. 12 is a cross-sectional view showing a schematic structure of a general image forming apparatus, and four color image forming means of yellow (Y), magenta (M), cyan (C) and black (K). 1 shows the overall configuration of an electrophotographic color printer including the.

In the figure, reference numerals 1Y, 1M, 1C, and 1K denote developing units for yellow, magenta, cyan, and black, and photosensitive drums 1aY, 1aM, 1aC, and 1aK that form electrostatic latent images of the respective colors. The electrostatic latent image is developed into a toner image with a developing device (not shown), which is unitized with the apparatus main body.

2Y, 2M, 2C and 2K are laser scanners 3Y, which form electrostatic latent images by exposing the photosensitive drums 1aY, 1aM, 1aC and 1aK according to image signals.
3M, 3C, and 3K are developing units 1Y, 1M, and 1 for each color.
Motors for driving C, 1K, and 4 are endless conveyor belts for sequentially conveying sheets of recording media to the image forming units of respective colors,
A driving roller 5 drives the conveyor belt 4.

Further, 6 is a motor for driving the drive roller 5, 7 is a fixing device for melting and fixing the toner transferred onto the paper, and 8 is a motor for driving the fixing device 7.

Next, the operation of the color printer having the above structure will be described.

Data to be printed is sent from an external PC (personal computer) to this printer, and when image formation according to the printer engine system is completed and printing is ready, paper is ejected from a paper cassette (not shown). The paper is supplied and reaches the conveyance belt 4, and the conveyance belt 4 sequentially conveys the paper to the image forming units of the respective colors. And
The image signals of the respective colors are transferred to the laser scanners 2Y, 2M, at the same timing as the conveyance of the sheet by the conveyance belt 4.
2C, 2K, photosensitive drums 1aY, 1aM, 1a
An electrostatic latent image is formed on each of C and 1aK.

The above electrostatic latent image is developed with toner by a developing device (not shown) and transferred onto a sheet at a transfer portion (not shown). In the example of the figure, images are sequentially formed in the order of Y, M, C and K. After that, the paper is separated from the conveyor belt 4, and the toner image is fixed on the paper by the heat in the fixing device 7 and discharged to the outside.

As described above, in the color printer described above, a color image is formed by superimposing images of four colors of yellow, magenta, cyan, and black on the paper conveyed by the conveyor belt 4. Therefore, if the writing positions of the four colors in the sub-scanning direction (belt conveying direction) do not match, a so-called color shift image problem occurs.

Other factors that cause color misregistration include misregistration of the writing position in the main scanning direction (the direction perpendicular to the belt conveying direction) and color misregistration due to variations in the main scanning line width.

In order to correct the color misregistration in the sub-scanning direction and the color misregistration in the main scanning direction, a color misregistration detection pattern for each color is formed by a toner image on the conveyor belt, and both patterns are provided on the downstream side of the conveyor belt. It is known that a pair of optical sensors provided on the sides detect this pattern and make the following various adjustments according to the detected shift amount.

FIG. 13 shows an example of the color shift detection pattern. In the figure, 101Y, 101M, 101C, 101K
And 102Y, 102M, 102C, and 102K are patterns for detecting the color shift amount of each color in the paper transport direction (sub-scanning direction), and 103Y, 103M, 103C, and 103K.
The patterns 104Y, 104M, 104C, and 104K are patterns for detecting the amount of color misregistration in the main scanning direction orthogonal to the paper transport direction of each color, and in this example, they have an inclination of 45 degrees. In addition, tsf1 to 4, tsr1 to 4, tmf1
4 to tmr1 to 4 and tmr1 to 4 indicate the detection timings of the above patterns, and the arrow indicates the moving direction of the conveyor belt 4.

Here, the moving speed of the conveyor belt 4 is vmm.
/ S and black (K) are the reference colors, and the theoretical distance between each color of the paper transport direction pattern and the black pattern is dsY.
mm, dsMmm, dsCmm, and the measured distances between the pattern for the sheet conveyance direction of each color and the pattern for the main scanning direction are dmfBmm, dmfYmm, dmfMmm, dm.
fCmm, dmrBmm, dmrYmm, dmrMm
If m and dmrCmm, each color (Y, M, C, K) in the transport direction when black (K) is used as a reference color
The positional deviation amount δes of is as follows.

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) Further, with respect to the main scanning direction, the positional deviation amounts δemf and δemr of each of the left and right colors are as follows. Like

[0015]   dmfB = v * (tmf1-tsf1) (Equation 4)   dmfY = v * (tmf2-tsf2) (Equation 5)   dmfM = v * (tmf3-tsf3) (Equation 6)   dmfC = v * (tmf4-tsf4) (Formula 7)   dmrB = v * (tmr1-tsr1) (Equation 8)   dmrY = v * (tmr2-tsr2) (Formula 9)   dmrM = v * (tmr3-tsr3) (Formula 10)   dmrC = v * (tmr4-tsr4) (Equation 11) The following equation is calculated from these equations.

ΔemfY = dmfY-dmfB (Equation 12) δemfM = dmfM-dmfB (Equation 13) δemfC = dmfC-dmfB (Equation 14) δemrY = dmrY-dmrB (Equation 15) δemrM = dmrM-dmrD-dmrM-dmrB dmrC-dmrB (Equation 17) The deviation direction can be determined from the positive or negative of the above calculation result, and δem
The writing position is corrected from f, and the main scanning width is corrected from δemr−δemf. If there is an error in the main scanning width, the writing position is calculated not only by δemf, but also by taking into account the amount of change in the image frequency that has changed due to the main scanning width correction.

FIG. 14 is a diagram showing the structure of the color misregistration detecting means 50, and FIG. 15 is a diagram showing the principle of color misregistration detection using the color misregistration detecting means 50. The positional relationship is shown.

The color shift detecting means 50 is composed of a light emitting element 51 such as an LED and a light receiving element 52 such as a photo sensor. A pattern 101 for detecting color shift is formed on the transport belt 4 by a toner image. Reference numeral 53 indicates a light emission optical path from the light emitting element 51, and reference numeral 54 indicates a light receiving optical path of the reflected light from the conveyor belt 4 or the color shift detecting pattern 101, which is received by the light receiving element 52.

The light emitting portion of the light emitting element 51 and the light receiving portion of the light receiving element 52 are constituted by specular reflection optical systems with the conveyor belt 4 as a reflecting surface, and specular reflection of the conveyor belt 4 and the pattern 101 for detecting the color misregistration. The position of the pattern 101 for detecting the color shift is detected based on the difference in light reflectance, that is, the difference in reflectance. As shown in FIG. 15, the color misregistration detection means 50 having such a configuration is installed at one location on each of the downstream sides of the conveyor belt 4.

On the other hand, the speed of the conveyor belt 4 moving in a circle changes due to the eccentricity of the driving roller 5 and the uneven thickness of the belt 5, and also due to the thermal expansion of the driving roller 5 and the like. FIG. 16 shows an example of changes in the speed of the conveyor belt 4.
Shown in.

As shown in FIG. 16, the change in speed due to temperature is superposed with the periodic change in speed caused by the eccentricity of the drive roller 5 and the uneven thickness of the belt 4. Therefore, the average speed of the conveyor belt 4 changes from moment to moment due to temperature rise inside the machine due to the use of the printer and environmental changes around the printer.

That is, as described above, even if the color misregistration is detected and adjusted to eliminate the color misregistration, the color misregistration in the sub-scanning direction depending on the speed of the conveyor belt 4 is proportional to the change width of the temperature. And grow bigger. Therefore, in order to prevent such color misregistration in the sub-scanning direction, it is general practice to detect the speed of the conveyor belt 4 with a sensor and control the speed of the conveyor belt 4 to be constant.

As a means for detecting the speed of the conveyor belt 4, as shown in FIG. 15, one or more detection members 55 each having a hole or a reflecting surface (reflecting material) are provided on the belt surface, and the detecting member 55 is provided as an optical sensor. A method of reading at 56 is known. Alternatively, a method of detecting the number of rotations of the driven roller that follows the belt 4 and obtaining the speed of the belt 4 is used.

In these detection methods, for example, when one hole or a reflecting surface is provided on the belt surface, the time required for one belt cycle is measured, and from the result, the average speed for one belt rotation is calculated, and one belt rotation is calculated. The motor speed is corrected every minute. That is, the change in the belt surface speed due to the knitting center of the drive roller 5 or the uneven thickness of the belt 4 is not corrected in real time, but the drift of the average speed due to thermal expansion of the drive roller 5 or the like is corrected.

[0025]

However, the conventional image forming apparatus as described above has the following problems.

When a hole or a reflecting surface is provided on the belt surface and is read by an optical sensor, the average speed for one rotation of the belt is obtained, and the motor rotation number is corrected for each one rotation of the belt, color shift detection is performed. There is a possibility that the speed of the conveyor belt may change while forming the pattern for use. Although the amount of change is such that it cannot be recognized by human eyes when it is output as an image, its influence cannot be ignored as a pattern for color misregistration detection, and the amount of change in color misregistration detection and color misregistration correction cannot be ignored. This leads to deterioration in accuracy, which in turn aggravates the actual color misregistration of the image.

Further, if there is a failure in the sensor for detecting the speed of the intermediate transfer member or the conveyor belt, accurate speed detection and speed correction cannot be performed, and the speed at the time of color misregistration detection and the actual speed There is a possibility that the speed at the time of printing is greatly deviated and the actual color misregistration of the image is deteriorated.

The present invention has been made in view of the above problems, and prevents deterioration in accuracy of color misregistration detection and color misregistration correction, and suppresses and aggravates actual color misregistration of an image. It is an object of the present invention to provide an image forming apparatus and a control method therefor.

[0029]

The image forming apparatus and the control method thereof according to the present invention are configured as follows.

(1) Toner images of a plurality of colors obtained by developing the latent image formed on the image bearing member are superposed and recorded on the intermediate transfer member orbiting the recording medium conveyed by the conveying belt. A method of controlling an image forming apparatus, comprising:
The latent image forming position of the image carrier is corrected according to the speed correction information of the intermediate transfer member or the conveyor belt.

(2) In the above (1), pattern detecting means for detecting a pattern for measuring color misregistration formed by toner on the intermediate transfer member or the conveyor belt and outputting a pattern detection signal, and the pattern detection signal. Further, there is provided a calculation means for calculating each color shift amount and a position correction means for correcting the latent image forming position of each color based on the calculated color shift amount.

(3) In the above (1) or (2),
Speed detecting means for detecting the speed of the intermediate transfer body or the conveyor belt, calculating means for calculating the deviation amount between the detected speed of the intermediate transfer body or the conveying belt and its target speed, and the intermediate value based on the calculated deviation amount. A speed correction means for correcting the speed of the transfer body or the conveyor belt is provided.

(4) In any one of the above (1) to (3), an intermediate transfer member or a conveyor belt is transferred from a drive control unit having a position correction unit and a speed correction unit to an image formation control unit for controlling an image forming operation. Notify the speed correction information of
4. The image forming apparatus according to claim 1, wherein the drive control unit determines whether to perform speed correction of the intermediate transfer member or the conveyance belt according to an instruction from the image formation control unit. .

(5) In the above (4), the drive control unit uses the speed correction information notified to the image formation control unit as the speed of the intermediate transfer member or the conveyance belt, and the deviation between the target speed and the actual speed. The amount and / or the signal indicating whether or not the amount of deviation between the actual speed and the target speed is less than or equal to a certain value are notified.

(6) In the above (4) or (5),
The image formation control unit first instructs the drive control unit to execute speed correction of the intermediate transfer body or the transport belt before forming the pattern for measuring the color misregistration, and then notified from the drive control unit. It is determined from the speed correction information whether or not the speed correction is completed and waits until the speed correction is completed, and after the speed correction is completed, the drive control unit is instructed to prohibit execution of the speed correction.

(7) In any one of the above (4) to (6), the image forming control unit, when performing a normal printing operation, tells the drive control unit before starting the printing operation. The execution of the speed correction of the intermediate transfer body or the conveyor belt is instructed.

(8) In any one of the above (4) to (7), the image forming control unit instructs the drive control unit to execute speed correction of the intermediate transfer member or the conveyor belt, and then
If it is judged from the speed correction information notified from the drive control unit whether or not the speed correction is completed, and if it is judged that the speed correction cannot be performed normally, the speed of the intermediate transfer member or the conveyor belt is sent to the drive control unit. Changed to instruct execution prohibition.

(9) In any one of the above (4) to (8), the speed correcting means adjusts the speed of the motor for driving the intermediate transfer body or the conveyor belt to adjust the speed of the intermediate transfer body or the conveyor belt. Was corrected.

(10) In any one of the above (4) to (9), the drive control section has a storage means for storing the number of rotations of the motor, and the execution of the speed correction of the intermediate transfer member or the conveyor belt is prohibited. At this time, the motor rotation speed that was stored before the execution of speed correction was prohibited was maintained.

(11) In any one of the above (4) to (10), the drive control unit has a storage means for storing the number of rotations of the motor, and the speed correction is performed during the speed correction of the intermediate transfer member or the conveyor belt. When the operation was performed normally, the motor rotation speed at that time is stored.

(12) In any one of the above (4) to (11), the motor for driving the intermediate transfer member or the conveyor belt is a DC motor.

(13) In any one of the above (4) to (12), the drive control section controls the drive of the motor for driving the intermediate transfer member or the conveyor belt by digital signal processing.

(14) In any one of (4) to (13) above, the drive control section is adapted to perform digital signal processing using a DSP.

(15) Toner images of a plurality of colors obtained by developing the latent image formed on the image bearing member are superposed and recorded on the intermediate transfer member which is orbiting or on the recording medium conveyed by the conveyor belt. A method of controlling an image forming apparatus, comprising: a drive control unit having a speed correcting unit that corrects a moving speed of the intermediate transfer member or a conveyor belt to the image forming control unit that controls an image forming operation. The belt speed correction information is notified, and the drive control unit determines whether or not to perform speed correction of the intermediate transfer member or the conveyance belt according to an instruction from the image formation control unit.

(16) In the above (15), the pattern for measuring the color shift formed by the toner on the intermediate transfer member or the conveyor belt is detected, and the pattern detection signal is output, and each color is detected from the pattern detection signal. The shift amount is calculated, and the latent image forming position of each color is corrected based on the calculated color shift amount.

(17) In (15) or (16) above, the speed of the intermediate transfer member or the conveyor belt is detected,
A deviation amount between the detected speed of the intermediate transfer member or the conveyor belt and its target speed is calculated, and the speed of the intermediate transfer member or the conveyor belt is corrected based on the calculated deviation amount.

(18) In any one of the above items (15) to (17), from the drive control unit to the image formation control unit, the speed of the intermediate transfer member or the conveyor belt, and the deviation amount between the target speed and the actual speed. The information of at least one of the signals indicating whether or not the deviation amount between the actual speed and the target speed is less than or equal to a certain value is notified.

(19) In any one of the above items (15) to (18), the image formation control unit first sends an intermediate transfer member or a conveyance unit to the drive control unit before forming a pattern for measuring color misregistration. Instruct the execution of belt speed correction,
Next, it is judged from the speed correction information notified from the drive control unit whether or not the speed correction is completed, and waits until the speed correction is completed,
After the speed correction is completed, the drive control unit is instructed to prohibit execution of the speed correction.

(20) In any one of the above (15) to (19), the image forming control unit, when performing a normal printing operation, instructs the drive control unit before starting the printing operation. The execution of the speed correction of the intermediate transfer body or the conveyor belt is instructed.

(21) In any one of the above items (15) to (21), the image forming control unit gives a notification from the drive control unit after instructing the drive control unit to execute speed correction of the intermediate transfer member or the conveyor belt. If it is determined that the speed correction is not completed normally based on the speed correction information that is displayed, and if it is determined that the speed correction cannot be performed normally, the drive control unit is prohibited from executing the speed correction of the intermediate transfer member or the conveyor belt. I tried to tell you.

(22) In any one of the above items (15) to (21), the speed correction means adjusts the speed of the motor for driving the intermediate transfer member or the conveyor belt to adjust the speed of the intermediate transfer member or the conveyor belt. Was corrected.

(23) In any one of the above (15) to (22), the motor rotation speed is stored and the speed correction is executed when the execution of the speed correction of the intermediate transfer member or the conveyor belt is prohibited. The motor rotation speed that was memorized before was prohibited was maintained.

(24) In any one of the above (15) to (22), when the speed correction is normally performed during the speed correction of the intermediate transfer member or the conveyor belt, the motor rotational speed at that time is stored. I decided to do it.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the illustrated embodiments.

(First Embodiment) The structure of the image forming apparatus according to the embodiment of the present invention is the same as that of FIG. 12, and the structure of the color shift detecting means is the same as that of FIGS. Further, the structure of the speed detecting means of the conveyor belt is the same as that of FIG. 15, and the other structures and operations are the same as those of the conventional example, and the description thereof will be omitted.

FIG. 1 is a block diagram showing a schematic configuration of a control system for an image forming apparatus according to the present invention, and here, a printer 10 is shown as the image forming apparatus.

In the figure, reference numeral 11 denotes a printer control section for controlling an image forming operation, which controls each device in the printer. 12 is a power supply for supplying power to each device in the printer,
Reference numeral 13 is a sensor for detecting the condition of each section in the printer, 14 is a drive control section for controlling a motor 15 which is a power source of each apparatus in the printer according to an instruction from the printer control section 11, and 16 is a printer 10. Is a display unit for notifying the user of the operating status of the above, and 17 is a communication controller for communicating between the printer 10 and an external host computer 18. The host computer 18 transfers data to be printed to the printer 10.

FIGS. 2 and 3 are block diagrams showing the structure of the main part of the embodiment of the present invention. In the figure, 20 is a DSP
(Digital signal processing circuit), 30 is a driver for controlling electric power to the DC brushless motor 40, 5 is a motor 40
Drive roller of the conveyor belt 4 driven by, 46 is a driven roller, and 56 is a detection member 5 provided on the conveyor belt 4.
5 is a sensor for detecting 5.

The DSP 20 controls the phase switching by the rotor position signal from the DC brushless motor 40, the start / stop control of the motor 40 by the control signal from the printer controller 11, and the speed command signal and the motor from the printer controller 11. The speed of the motor 40 is controlled via the driver 30 by comparing the output of the speed detecting means 40.

Further, the speed of the conveyor belt 4 is detected by the signal from the sensor 56, and the rotation speed of the DC brushless motor 40 is corrected so that the speed of the conveyor belt 4 becomes a target speed.

The DC brushless motor 40 has U, V, W
3 has a three-phase star-connected coil 43 and a rotor 44. Furthermore, three Hall elements 42 for detecting the magnetic poles of the rotor 44 are provided as position detecting means for the rotor 44,
Its output terminal is connected to the DSP 20. Further, it has a rotational speed detecting means composed of a magnetic pattern 45 and a magnetic sensor 41 provided on the outer circumference of the rotor 44, and the output thereof is inputted to the DSP.

Reference numeral 30 denotes a driver for driving the DC brushless motor 40, which includes three high-side transistors 31 and three low-side transistors 32, and U of the coil 43,
It is connected to the V and W coils 43. A current detection resistor 34 converts the motor drive current into a voltage. The generated voltage is taken into the D / A port of the DSP 20.

FIG. 4 is a block diagram showing the configuration of the DSP 20. In the figure, 21 is a program controller, 22
a is an ALU that performs addition / subtraction and logical operations, 22b is a MAC that performs product-sum operations, 23 is a data memory that stores data,
24 is a program memory for storing programs, and 25a
Is a data memory bus, 25b is a program memory bus,
26 is an A / D port, 27 is a serial port, 28 is a timer, and 29 is an I / O port.

In this way, the memory is made independent for the data and the program, the bus is also separated into the data bus and the program bus, and the multiplication and the addition are executed in one machine cycle.
Having C enables high-speed calculation.

The DSP 20 specifies the position of the rotor 44 by the rotor position signals HU, HV, HW generated by the Hall element 42, and generates a phase switching signal. The phase switching signals UU, UV, UW and LU, LV, LW control the transistors 31 and 32 of the driver 30 to turn on and off, and sequentially switch the phases to be excited to rotate the rotor 44.

Further, the DSP 20 compares the rotation speed target value of the DC brushless motor 40 with the rotation speed information, and performs PWM.
Generate and output a signal. This PWM signal is 0 at du
The duty becomes 100 at ty0 and 255. And PW
The M signal is logically ANDed by the phase switching signals UU, UV, UW and the NAND gate 33 to chop the drive current to control the rotation speed of the motor 40. It should be noted that the DSP 20 may perform all processing without using the NAND gate 33.

In this embodiment, in the printer 10, from the drive controller 14 having the color misregistration correction means and the speed correction means of the conveyor belt 4 to the image formation controller 11 which controls the image forming operation, the conveyor belt speed correction information. In addition to the notification, the drive control unit 14 determines (switches) whether or not to correct the speed of the conveyor belt according to an instruction from the image formation control unit 11. Then, the color misregistration correction is performed after the speed adjustment of the transport belt 4 is performed and then the speed adjustment is prohibited.

Next, the control operation of this embodiment will be described with reference to the flow charts of FIGS. The control processing shown in these flowcharts and the flowcharts of FIGS. 8 to 11 of another embodiment described later is performed by the printer 10 shown in FIG.
It is executed by the printer control unit 11 and the drive control unit 14 according to a program stored in advance.

FIG. 5 is a flow chart showing the color misregistration detection sequence operation of the printer controller 11 of this embodiment.

The printer control unit 11 instructs the drive control unit 14 to execute the speed correction of the conveyor belt 4 (step 1
01), the timer 28 for timeout processing is set (step 102). Then, the drive control unit 14
The speed correction information (correction result) of the conveyor belt 4 notified by is received (step 103), and it is determined whether the speed correction of the conveyor belt 4 is completed (step 104).
The speed correction of the conveyor belt 4 is ended when the deviation amount from the target speed falls within a predetermined value.

The speed correction information of the conveyor belt 4 notified by the drive controller 14 is the speed information of the conveyor belt 4, or the amount of deviation between the target conveyor belt 4 speed and the actual conveyor belt 4 speed. Or the target conveyor belt 4
Can be used as a signal indicating whether or not the amount of deviation between the actual speed of the conveyor belt 4 and the actual speed of the conveyor belt 4 is below a certain value.

If the speed of the conveyor belt 4 has not been corrected, it is confirmed whether the timer value has reached 0 (step 10
5) If the timer value is not 0, -1 is subtracted from the timer value at constant intervals (step 106). If the speed of the conveyor belt 4 has not been corrected even after the lapse of a predetermined time, it is determined that the speed of the conveyor belt 4 is abnormal (step 108).

When the speed correction is completed within the predetermined time, the drive controller 14 is instructed to prohibit the speed correction of the conveyor belt 4 (step 107). Next, the color misregistration detection pattern formation and the color misregistration amount calculation are executed. Since the color misregistration detection pattern formation and the color misregistration amount calculation are the same as those in the conventional example, the description thereof will be omitted.

FIG. 6 is a flow chart showing the print sequence operation of the printer control unit 11.

The printer control unit 11 instructs the drive control unit 14 to execute the speed correction of the conveyor belt 4 (step 1
At the same time, the timer 28 for time-out processing is set (step 112). Then, the drive control unit 14
Is received (step 113), and it is determined whether the speed correction of the conveyor belt 4 is completed (step 114). The speed correction of the conveyor belt 4 is ended when the deviation amount from the target speed falls within a predetermined value.

The speed correction information of the conveyor belt 4 notified by the drive controller 14 is the speed information of the conveyor belt 4, or the amount of deviation between the target conveyor belt 4 speed and the actual conveyor belt 4 speed. Or the target conveyor belt 4
Can be used as a signal indicating whether or not the amount of deviation between the actual speed of the conveyor belt 4 and the actual speed of the conveyor belt 4 is below a certain value.

If the speed of the conveyor belt 4 has not been corrected, it is confirmed whether the timer value has reached 0 (step 11
5) If the timer value is not 0, -1 is subtracted from the timer value at regular intervals (step 116). If the speed of the conveyor belt 4 has not been corrected even after the lapse of a predetermined time, it is determined that the speed of the conveyor belt 4 is abnormal (step 118).

When the speed correction is completed within the predetermined time, the drive controller 14 is instructed to prohibit the speed correction of the conveyor belt 4 (step 117), and the printing operation on the paper is performed. Since this printing operation is similar to that of the conventional example, description thereof will be omitted.

FIG. 7 is a flow chart showing the sequence operation of the drive control unit 14.

When the drive control unit 14 is instructed by the printer control unit 11 to execute the speed correction of the conveyor belt 4 (step 121), the drive motor of the conveyor belt 4 rotates in advance as an initial rotation speed set value. Rotate by a number (step 122). Next, the timer value is set (step 123). This timer value is set to a time sufficient for the speed of the conveyor belt 4 to stabilize.

Thereafter, the timer value is decremented at regular intervals (step 124), and when it reaches 0 (step 125), the speed measurement of the conveyor belt 4 is started. That is, when the photosensor detects the detection member provided on the surface of the conveyor belt 4 (step 126), the time measuring counter is cleared (step 127), and thereafter, the count is incremented at constant intervals (step 128).

Next, when the photosensor detects the detection member on the surface of the conveyor belt 4 (step 129), the counter value at that time, that is, the time required for one round of the belt is held (step 130). Then, the measured time required for one round of the belt is compared with a reference value indicating the time required for one round of the belt when the conveyor belt 4 is rotated at an ideal speed. This reference value may set a reference lower limit and a reference value upper limit.

As a result of the above comparison, when the speed of the conveyor belt 4 is lower than the ideal speed, that is, when the measured counter value is larger than the reference value (step 131), the speed of the drive motor for the conveyor belt 4 is accelerated (step 131). Step 13
2). If the speed of the conveyor belt 4 is higher than the ideal speed, that is, if the measured counter value is smaller than the reference value (step 133), the speed of the drive motor for the conveyor belt 4 is reduced (step 134).

Thereafter, the printer controller 11 is informed of the speed correction signal of the conveyor belt 4 (step 135). As the speed correction information of the conveyor belt 4, the speed information of the conveyor belt 4, a deviation amount between the target speed of the conveyor belt 4 and the actual speed of the conveyor belt 4, or the target speed of the conveyor belt 4 and the actual speed of the conveyor belt 4. It can be a signal indicating whether or not the deviation amount of the speed of the conveyor belt 4 is less than or equal to a certain value.

Here, when the drive motor of the conveyor belt 4 is being driven and execution of the speed correction of the conveyor belt 4 is not prohibited, the above operation is repeated to correct the speed of the conveyor belt 4.

Further, when the difference between the speed of the conveyor belt 4 and the ideal speed is less than a certain value, the motor speed at that time is stored and the initial rotation speed of the motor at the next motor startup. Used as a set value.

It should be noted that the correction width of the motor speed to be corrected at one time is not more than a value that cannot be recognized by the human eye as image deterioration on the actual printed image.

(Second Embodiment) Next, a second embodiment of the present invention will be described.

The image forming apparatus configuration of this embodiment and the schematic configuration of the control system are the same as those in the first embodiment, and therefore their explanations are omitted. In the present embodiment, when the belt speed correction cannot be performed normally during execution of the color misregistration detection sequence, the printer control unit 11 instructs the drive control unit 14 to prohibit execution of speed correction during the printing sequence, and performs the printing operation.

FIG. 8 is a flow chart showing the color misregistration detection sequence operation of the printer controller 11 of this embodiment.

The printer control section 11 instructs the drive control section 14 to execute speed correction of the conveyor belt 4 (step 2).
01), the timer 28 for time-out processing is set (step 202). Then, the drive control unit 14
Is received (step 203), and it is determined whether the speed correction of the conveyor belt 4 is completed (step 204). The speed correction of the conveyor belt 4 is ended when the deviation amount from the target speed falls within a predetermined value.

The speed correction information of the conveyor belt 4 notified by the drive controller 14 is the speed information of the conveyor belt 4, or the amount of deviation between the target speed of the conveyor belt 4 and the actual speed of the conveyor belt 4. Or the target conveyor belt 4
Can be used as a signal indicating whether or not the amount of deviation between the actual speed of the conveyor belt 4 and the actual speed of the conveyor belt 4 is below a certain value.

If the speed of the conveyor belt 4 has not been corrected, it is confirmed whether the timer value has reached 0 (step 20).
5) If the timer value is not 0, -1 is subtracted from the timer value at constant intervals (step 206). If the speed correction of the conveyor belt 4 is not completed even after the lapse of a predetermined time, the speed abnormality flag of the conveyor belt 4 is set (step 208), and the drive controller 14 executes the speed correction of the conveyor belt 4. Is prohibited (step 209).

When the speed correction is completed within the predetermined time, the speed abnormality flag of the conveyor belt 4 is cleared (step 207), and the drive controller 14 is instructed to prohibit the execution of the speed correction of the conveyor belt 4 (step). 209). Next, color misregistration detection pattern formation and color misregistration amount calculation are executed. The color misregistration detection pattern formation and the color misregistration amount calculation are the same as those in the conventional example, and the description thereof will be omitted.

FIG. 9 is a flow chart showing the print sequence operation of the printer controller 11 of this embodiment.

The printer control section 11 determines whether or not the belt speed correction at the time of executing the previous color misregistration detection sequence is normally completed (step 211). As a result, if it has not been normally completed last time, the drive control unit 14 is instructed to prohibit execution of belt speed correction (step 218), and the printing operation on the paper is performed. Since this printing operation is similar to that of the conventional example, description thereof will be omitted.

When the belt speed correction is normally completed, the drive controller 14 is instructed to execute the speed correction of the conveyor belt 4 (step 212), and the timer 28 for time-out processing is set (step 213). ). Then, the speed correction information of the conveyor belt 4 notified by the drive controller 14 is received (step 214), and the conveyor belt 4 is received.
It is determined whether or not the speed correction has been completed (step 21)
5). The speed correction of the conveyor belt 4 is ended when the deviation amount from the target speed falls within a predetermined value.

The speed correction information of the conveyor belt 4 notified by the drive controller 14 is the speed information of the conveyor belt 4, or the deviation amount between the target conveyor belt 4 speed and the actual conveyor belt 4 speed. Or the target conveyor belt 4
Can be used as a signal indicating whether or not the amount of deviation between the actual speed of the conveyor belt 4 and the actual speed of the conveyor belt 4 is below a certain value.

When the speed correction of the conveyor belt 4 is not completed, it is confirmed whether the timer value has become 0 (step 21
6) If the timer value is not 0, -1 is subtracted from the timer value at constant intervals (step 217). If the speed correction of the conveyor belt 4 is not completed even after the lapse of a predetermined time, the drive controller 14 is instructed to prohibit execution of the speed correction of the conveyor belt 4 (step 218) and printing is performed on the paper. .

When the speed correction is completed within the predetermined time, the drive controller 14 is instructed to prohibit the speed correction of the conveyor belt 4 (step 218), and printing is performed on the paper.
Since this printing operation is similar to that of the conventional example, description thereof will be omitted.

The sequence operation of the drive control unit 14 of this embodiment is the same as that of the first embodiment, so its explanation is omitted.

(Third Embodiment) Next, a third embodiment of the present invention will be described.

The image forming apparatus configuration of this embodiment and the schematic configuration of the control system are the same as those in the first embodiment, and therefore their explanations are omitted. In this embodiment, when continuous printing is performed for a predetermined number of sheets or more, execution of speed correction of the conveyor belt 4 is instructed again. Further, the color misregistration detection sequence operation of the printer control unit 11 is the same as that of the second embodiment, and therefore its explanation is omitted.

FIG. 10 is a flow chart showing the print sequence operation of the printer controller 11 of this embodiment.

The printer control section 11 determines whether or not the belt speed correction at the time of executing the previous color misregistration detection sequence is normally completed (step 301). As a result, if it has not ended normally last time, the drive control unit 14 is instructed to prohibit execution of the speed correction of the conveyor belt 4 (step 308)
Performs printing operation on paper. Since this printing operation is similar to that of the conventional example, description thereof will be omitted.

When the speed correction of the conveyor belt 4 is normally completed, the drive controller 14 is instructed to execute the speed correction of the conveyor belt 4 (step 302) and the timer 28 for time-out processing is set. (Step 30
3). Then, the drive controller 14 receives the speed correction information of the conveyor belt 4 notified (step 304), and determines whether the speed correction of the conveyor belt 4 is completed (step 305). The speed correction of the conveyor belt 4 is ended when the deviation amount from the target speed falls within a predetermined value.

The speed correction information of the conveyor belt 4 notified by the drive controller 14 is the speed information of the conveyor belt 4, or the amount of deviation between the target conveyor belt 4 speed and the actual conveyor belt 4 speed. Or the target conveyor belt 4
Can be used as a signal indicating whether or not the amount of deviation between the actual speed of the conveyor belt 4 and the actual speed of the conveyor belt 4 is below a certain value.

If the speed of the conveyor belt 4 has not been corrected, check whether the timer value has reached 0 (step 30
6) If the timer value is not 0, -1 is subtracted from the timer value at regular intervals (step 307). If the speed correction of the conveyor belt 4 is not completed even after the lapse of a predetermined time, the drive controller 14 is instructed to prohibit the speed correction of the conveyor belt 4 (step 308), and printing is performed on the paper. .

When the speed correction is completed within the predetermined time, the drive controller 14 is instructed to prohibit the speed correction of the conveyor belt 4 (step 308 in the figure), and printing is performed on the paper. Since this printing operation is similar to that of the conventional example, description thereof will be omitted.

In the case of continuous printing, when printing is performed to such an extent that the temperature drift of the speed of the conveyor belt 4 affects the image and the temperature inside the apparatus main body rises (for example, continuous 100 Sheet), the speed correction sequence of the conveyor belt 4 described above is executed again (step 309,
310).

The sequence operation of the drive control unit 14 of this embodiment is the same as that of the first embodiment, so its explanation is omitted.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.

The structure of the image forming apparatus and the schematic structure of the control system of this embodiment are the same as those of the first embodiment, and therefore their explanations are omitted. In this embodiment, the conveyor belt 4 is always operated during the printing operation.
Perform the speed correction of. Further, the color misregistration detection sequence operation of the printer control unit 11 is the same as that of the second embodiment, and therefore its explanation is omitted.

FIG. 11 is a flow chart showing the print sequence operation of the printer controller 11 of this embodiment.

The printer control unit 11 determines whether or not the belt speed correction at the time of executing the previous color misregistration detection sequence is normally completed (step 401). As a result, if it has not ended normally the previous time, the drive control unit 14 is instructed to prohibit execution of speed correction of the conveyor belt 4 (step 408),
Performs printing operation on paper. Since this printing operation is similar to that of the conventional example, description thereof will be omitted.

When the belt speed correction is normally completed, the drive control unit 14 is instructed to execute the speed correction of the conveyor belt 4 (step 402) and the timer 28 for time-out processing is set (step 403). ). Then, the speed correction information of the conveyor belt 4 notified by the drive controller 14 is received (step 404), and the conveyor belt 4 is received.
It is determined whether or not the speed correction has been completed (step 40).
5). The speed correction of the conveyor belt 4 is ended when the deviation amount from the target speed falls within a predetermined value.

The speed correction information of the conveyor belt 4 notified by the drive controller 14 is the speed information of the conveyor belt 4, or the amount of deviation between the target conveyor belt 4 speed and the actual conveyor belt 4 speed. Or the target conveyor belt 4
Can be used as a signal indicating whether or not the amount of deviation between the actual speed of the conveyor belt 4 and the actual speed of the conveyor belt 4 is below a certain value.

If the speed of the conveyor belt 4 has not been corrected, it is confirmed whether the timer value has reached 0 (step 40
6) If the timer value is not 0, -1 is subtracted from the timer value at regular intervals (step 407). If the speed correction of the conveyor belt 4 is not completed even after the lapse of a predetermined time, the drive controller 14 is instructed to prohibit the speed correction of the conveyor belt 4 (step 408), and printing is performed on the paper. .

When the speed correction is completed within the predetermined time, printing is performed on the paper. Since this printing operation is similar to that of the conventional example, description thereof will be omitted. The sequence operation of the drive control unit 14 is the same as that of the first embodiment, and the description thereof will be omitted.

[0120]

As described above, according to the present invention,
It is possible to prevent the accuracy of color misregistration detection and color misregistration correction from deteriorating, and thus suppress the deterioration of the actual color misregistration of the image.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a control system of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a main part of an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a main part of an embodiment of the present invention.

FIG. 4 is a block diagram showing the configuration of the DSP of the embodiment.

FIG. 5 is a flowchart showing the operation of the printer control unit of the first embodiment.

FIG. 6 is a flowchart showing the operation of the printer control unit of the first embodiment.

FIG. 7 is a flowchart showing the operation of the drive control unit of the first embodiment.

FIG. 8 is a flowchart showing the operation of the printer control unit of the second embodiment.

FIG. 9 is a flowchart showing the operation of the printer control unit of the second embodiment.

FIG. 10 is a flowchart showing the operation of the printer control unit of the third embodiment.

FIG. 11 is a flowchart showing the operation of the printer control unit of the fourth embodiment.

FIG. 12 is a sectional view showing a schematic configuration of a general image forming apparatus.

FIG. 13 is a plan view showing an example of a color shift detection pattern.

FIG. 14 is an explanatory diagram showing a configuration of a color shift detection unit.

FIG. 15 is a perspective view showing the principle of color misregistration detection.

FIG. 16 is a diagram showing a change in speed of the conveyor belt

[Explanation of symbols]

1Y development unit 1M development unit 1C development unit 1K developing unit 2Y laser scanner 2M laser scanner 2C laser scanner 2K laser scanner 3Y motor 3M motor 3C motor 3K motor 4 Conveyor belt 5 drive roller 6 motor 7 fixing device 8 motor 10 Printer 11 Printer control unit 12 power supplies 13 sensors 14 Drive controller 15 Motors 16 Display 17 Communication controller 18 Host computer 20 DSP 21 Program Controller 22a ALU 22b MAC 23 Data memory 24 program memory 25a data memory bus 25b program memory bus 26 A / D port 27 serial ports 28 timer 29 I / O ports 30 drivers 31 High-side transistor 32 low side transistor 33 Nand Gate 34 Current detection resistor 40 DC brushless motor 41 Magnetic sensor 42 Hall element 43 coils 44 rotor 45 magnetic pattern 46 Driven roller 50 Color shift detection means 51 light emitting element 52 Light receiving element 53 Light emission path 54 Light receiving optical path 55 Detection member 56 sensor 101 Color shift detection pattern 102 Color shift detection pattern 103 Color shift detection pattern 104 Color shift detection pattern

Front page continued (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/14 B41J 3/00 M (72) Inventor Riki Imaizumi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. In-house F-term (reference) 2C362 BA52 BA66 BA71 BB46 BB48 BB50 CA22 CA39 CB47 CB73 2H027 DA09 DA20 DA35 DA39 DE02 DE04 DE07 EB04 EC03 EC06 EC07 EC10 ED07 ED16 EE03 EE04 EE07 AD07 AD05 BB07 AD02 BB07 AD0217A02 AD0217A02 AB02 AD02A02 AD0217A02 AD0217A02 AD0217A02A02 AD0217A02 AD0217A02 AD0217A02 BB56 2H200 FA01 FA04 GA12 GA23 GA34 GA47 GB25 JC03 JC09 JC10 JC19 JC20 PA10 PA11 PA19 PA24 PA28 PB13 PB16 PB38 PB39

Claims (24)

[Claims] 1. An image recorded by superimposing toner images of a plurality of colors obtained by developing a latent image formed on an image bearing member, on an intermediate transfer member that circulates or on a recording medium conveyed by a conveyor belt. The image forming apparatus includes position correcting means for correcting the latent image forming position of each color of the image carrier and speed correcting means for correcting the moving speed of the intermediate transfer body or the transport belt, and the intermediate transfer body Alternatively, the image forming apparatus is characterized in that the latent image forming position is corrected according to the speed correction information of the conveyor belt. 2. A pattern detecting means for detecting a pattern for measuring color shift formed by toner on an intermediate transfer body or a conveyor belt and outputting a pattern detection signal, and a color shift amount for each color from the pattern detection signal. The image forming apparatus according to claim 1, further comprising a calculating unit that calculates, wherein the position correcting unit corrects the latent image forming position of each color based on the calculated color shift amount. 3. A speed detecting means for detecting the speed of the intermediate transfer body or the conveyor belt, and a calculating means for calculating a deviation amount between the detected speed of the intermediate transfer body or the conveyor belt and its target speed. 3. The image forming apparatus according to claim 1, wherein the correction unit corrects the speed of the intermediate transfer body or the conveyor belt based on the calculated shift amount. 4. A drive control unit having a position correction unit and a speed correction unit notifies the image formation control unit controlling an image forming operation of speed correction information of an intermediate transfer member or a conveyor belt, and the drive control unit performs the above-mentioned operation. 4. The image forming apparatus according to claim 1, wherein whether to perform speed correction of the intermediate transfer member or the conveyance belt is determined according to an instruction from the image forming control unit. 5. The speed control information notified to the image forming control section by the drive control section is the speed of the intermediate transfer member or the conveyor belt, the amount of deviation between the target speed and the actual speed, the actual speed and the target speed. The image forming apparatus according to claim 4, wherein at least one of information of a signal indicating whether the amount of deviation from the speed is less than or equal to a certain value is notified. 6. The image forming control unit instructs the drive control unit to execute speed correction of the intermediate transfer member or the conveyor belt before forming the pattern for measuring the color shift, and then the drive control unit. From the speed correction information notified from the unit, it is determined whether or not the speed correction is completed, wait until the speed correction is completed, and after the speed correction is completed, the drive control unit is instructed to prohibit execution of the speed correction. The image forming apparatus according to claim 4 or 5. 7. The image forming controller, when performing a normal printing operation, instructs the drive controller to execute speed correction of the intermediate transfer body or the transport belt before starting the printing operation. The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. 8. The image forming control unit, after instructing the drive control unit to execute the speed correction of the intermediate transfer member or the conveyor belt, determines whether or not the speed correction is completed from the speed correction information notified from the drive control unit. However, when it is determined that the speed correction cannot be performed normally, the drive controller is instructed to prohibit the execution of the speed correction of the intermediate transfer member or the conveyor belt. An image forming apparatus according to claim 2. 9. The speed correcting means corrects the speed of the intermediate transfer member or the conveyor belt by adjusting the speed of a motor for driving the intermediate transfer member or the conveyor belt. The image forming apparatus according to any one of 1. 10. The drive control unit has storage means for storing the number of rotations of the motor, and when the execution of the speed correction of the intermediate transfer body or the conveyance belt is prohibited, the storage is made before the execution of the speed correction is prohibited. 10. The image forming apparatus according to claim 4, wherein the number of rotations of the motor is maintained. 11. The drive control unit has a storage unit for storing the motor rotation speed, and when the speed correction can be normally performed during execution of the speed correction of the intermediate transfer member or the conveyor belt, the motor rotation speed at that time. The image forming apparatus according to claim 4, wherein the image forming apparatus stores therein. 12. The image forming apparatus according to claim 4, wherein the motor that drives the intermediate transfer member or the conveyor belt is a DC motor. 13. The image forming apparatus according to claim 4, wherein the drive control unit performs drive control of a motor that drives the intermediate transfer member or the conveyor belt by digital signal processing. 14. The drive control unit performs digital signal processing by using a DSP.
The image forming apparatus according to any one of 1. 15. An image to be recorded by superimposing toner images of a plurality of colors obtained by developing a latent image formed on an image bearing member on an intermediate transfer member that revolves or on a recording medium conveyed by a conveyor belt. A method for controlling an intermediate transfer member or a conveyor belt, comprising: a drive controller having a speed correction unit that corrects a moving speed of the intermediate transfer member or the conveyor belt to an image forming controller that controls an image forming operation. Of the image forming apparatus, the drive control unit determines whether or not to perform speed correction of the intermediate transfer body or the transport belt in accordance with an instruction from the image forming control unit in the drive control unit. Control method. 16. A color misregistration measurement pattern formed by toner on an intermediate transfer member or a conveyor belt is detected, a pattern detection signal is output, and each color misregistration amount is calculated from the pattern detection signal. 16. The method of controlling an image forming apparatus according to claim 15, wherein the latent image forming position of each color is corrected based on the color shift amount. 17. A speed of an intermediate transfer member or a conveyor belt is detected, a deviation amount between the detected speed of the intermediate transfer member or the conveyor belt and its target speed is calculated, and the intermediate transfer member is calculated based on the calculated deviation amount. Alternatively, the control method of the image forming apparatus according to claim 15 or 16, wherein the speed of the conveyor belt is corrected. 18. The drive control unit transfers the speed of the intermediate transfer member or the conveyance belt to the image formation control unit, the amount of deviation between the target speed and the actual speed, and the amount of deviation between the actual speed and the target speed. 18. The method of controlling an image forming apparatus according to claim 15, wherein at least one of information of signals indicating whether the value is less than or equal to a certain value is notified. 19. The image forming control unit first instructs the drive control unit to execute speed correction of the intermediate transfer member or the transport belt before forming a pattern for measuring color misregistration,
Next, it is judged from the speed correction information notified from the drive control unit whether or not the speed correction is completed, and waits until the speed correction is completed,
16. The drive control unit is instructed to prohibit execution of speed correction after the speed correction is completed.
19. The method for controlling an image forming apparatus according to any one of 18 to 18. 20. When performing a normal printing operation, the image forming control unit instructs the drive control unit to execute speed correction of the intermediate transfer member or the transport belt before starting the printing operation. 20. The method of controlling an image forming apparatus according to claim 15, wherein the method is as described above. 21. The image forming control unit, after instructing the drive control unit to execute the speed correction of the intermediate transfer member or the conveyor belt, determines whether or not the speed correction is completed from the speed correction information notified from the drive control unit. 16. However, when it is determined that the speed correction cannot be performed normally, the drive control unit is instructed to prohibit execution of the speed correction of the intermediate transfer member or the conveyor belt. 21. A method for controlling an image forming apparatus according to any one of 20. 22. The speed correcting means is adapted to correct the speed of the intermediate transfer member or the conveyor belt by adjusting the speed of a motor for driving the intermediate transfer member or the conveyor belt. 22. A method for controlling an image forming apparatus according to any one of 15 to 21. 23. The motor rotation speed is stored, and when the execution of the speed correction of the intermediate transfer body or the conveyor belt is prohibited, the stored motor rotation speed is maintained before the execution of the speed correction is prohibited. 23. The method for controlling an image forming apparatus according to claim 15, wherein the method is as described above. 24. When the speed correction is normally performed during the speed correction of the intermediate transfer member or the conveyor belt, the motor rotational speed at that time is stored. A method for controlling an image forming apparatus according to any one of 1.