JP2003162119A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately keep the accuracy of aligning the phases of a main body gear and a drum gear especially over a long term in a color image forming apparatus using a plurality of color materials. <P>SOLUTION: In the case of aligning the phases of the yellow (Y), magenta (M) and cyan (C) color drum gears and the black (K) drum gear, a mutual phase error is measured and stored in a memory. In the case of connecting them by a clutch, a new correction value is set from the past errors, whereby influence by the fitness or the deterioration of the clutch is eliminated, and alignment is accurately performed over a long term. In the case of setting the new correction value from the past errors, a method in which an error value obtained every time a mode is changed is added to α, for example, and utilized, or a method in which a mean value is measured every time the mode is changed by the specified number of times so as to set the correction value is adopted. <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 a color image forming apparatus using a plurality of color materials.

[0002]

2. Description of the Related Art Today, a tandem type printer is used because of its superior printing speed. In this printer device, image forming units for yellow (Y), magenta (M), cyan (C), and black (B) are used, toner images are sequentially transferred onto paper, and a color image is created by heat fixing processing. . For this reason, the printing positions of the respective colors must be accurately matched, and the phase of the gear must also be adjusted accurately.

Conventionally, the above-mentioned phase matching is performed as follows. That is, first, in order to rotate the photosensitive drum, the clutch is turned on to connect the rotational force of the motor to the drum gear. Next, for example, the phase difference between the black (K) and yellow (Y) drum gears is measured, and the phase difference between the drive gear that drives the black (K) drum gear and the drive gear that drives the yellow (Y) drum gear. Is measured and the clutch switching time is calculated. For example, if the phase difference between the drum gears is t1 and the phase difference between the drive gears is t2, the time required to reconnect the clutch after the clutch is actually disengaged is t1 + t2 + α.

Here, the above α is a value determined by the characteristics of the image forming apparatus, and is, for example, substantially the same for each model or each version of the model.

[0005]

However, when the phase matching is performed by the above method, the above α changes with the continuation of the printing process, and the phase shift occurs. For example, the phase accuracy decreases due to the so-called familiarity and deterioration of the clutch plate. In this case, the driving speed may be reduced, but it takes a long time to perform the phase adjustment.

The present invention has been made in view of the above circumstances, and provides an image forming apparatus for easily performing phase adjustment and accurately maintaining the phase alignment accuracy for a long time.

[0007]

According to the invention described in claim 1, the above-mentioned problems are composed of a first image carrier drum and one or more other image carrier drums, each of which is formed by the same molding process. A plurality of image carrier drums that are formed, are provided with marks and have the same shape, and that are driven in parallel;
Engaging a driven gear of the image carrier drum, and a first drive transmission mechanism including a first drive gear having a mark, and the driven gears of the one or more other image carrier drums. And a second drive transmission mechanism including one or more gears formed by the same molding process as the first drive gear and having the same shape with markings, the first drive transmission mechanism and the second drive. A drive source for transmitting a driving force to the transmission mechanism, a first drive transmission mode for transmitting the driving force of the drive source only to the first drive transmission mechanism, and a first drive transmission mechanism and a second drive transmission mechanism. Drive force switching means for switching to a second drive transmission mode for transmitting to both, first drive gear detecting means for detecting a home position of the first drive gear via a mark of the first drive gear, Home of the second drive gear through the marks of the second drive gear A second drive gear detecting means for detecting a position, a first driven gear detecting means for detecting a home position of the first driven gear through a mark of the first driven gear, and a first driven gear detecting means for detecting a home position of the first driven gear. Second driven gear detecting means for detecting the home position of the second driven gear through the mark of the second driven gear, and the first image carrier corresponding to the first drive transmission mode. First image forming mode executing means for operating the image forming means acting on the body drum,
Second image forming mode executing means for operating the image forming means acting on the plurality of image carrier drums corresponding to the second drive transmission mode, and the first driven member in the second image forming mode. The time from the detection of the first driven gear by the gear detection means to the detection of the second driven gear by the second driven gear detection means and the time by the first drive gear detection means. Measuring means for measuring the switching error of the driving force switching means based on the time from the detection of the first driving gear to the detection of the second driving gear by the second driving gear detection means, and the measurement result. This can be achieved by providing an image forming apparatus provided with a storage unit for storing the above, and an adjusting unit for adjusting the timing of the driving force switching unit based on the measurement result stored in the storage unit.

With this structure, it is possible to provide an image forming apparatus in which the phase matching accuracy can be accurately maintained for a long period of time. According to a second aspect, in the invention according to the first aspect, the storage unit is sequentially overwritten with the error information as the measurement result, and the adjusting unit uses the error information to switch the driving force. This is a configuration for adjusting the switching timing of the means.

With this configuration, a small amount of error information is stored in the storage means, so that the memory capacity can be reduced. According to a third aspect, in the invention according to the first aspect, a predetermined number of error information which is the measurement result is stored in the storage means, and the adjustment is performed based on an average value of the predetermined number of error information. The means adjusts the switching timing of the driving force switching means.

With this configuration, the clutch can be switched more accurately.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an example of a tandem type printer device (image forming apparatus) used for the description of the present embodiment.

In FIG. 1, the printer device 1 comprises an image forming section 2, a double-sided printing transport unit 3, and a sheet feeding section 4. Here, the image forming unit 2 has a configuration in which four image forming units 5 to 8 are arranged side by side, and magenta (M), cyan (C), yellow (Y), from the right side to the left side of the drawing of FIG. They are arranged in the order of black (K).
The magenta (M), cyan (C), and yellow (Y) image forming units 5 to 7 are used when performing color printing by subtractive color mixing, and are black (K).
The image forming unit 8 is used for the color printing, and is also used alone for monochrome printing.

Here, each of the image forming units 5 to 8 is composed of a drum set C1 and a toner set C2, and has the same structure except for the developer (color thereof) contained in the developing container. Therefore, the configuration will be described by taking the image forming unit 7 for yellow (Y) as an example. Drum set C
1 includes a photosensitive drum, a charger, and a cleaner, and the toner set C2 includes a developing roll and toner.

The peripheral surface of the photosensitive drum 9 is made of, for example, an organic photoconductive material, and in the vicinity of the peripheral surface of the photosensitive drum 9, a charger 10a, a print head 10b, and a developing roll 10 are provided.
c, a transfer device 10d, and a cleaner 10e are sequentially arranged. The photosensitive drum 9 rotates in the direction of the arrow, and first the charger 1
By applying the electric charge from 0a, the peripheral surface of the photosensitive drum 9 is uniformly charged. Then, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 9 by optical writing based on the print information from the print head 10b, and a toner image is formed by the development processing by the developing roll 10c. At this time, the toner image formed on the peripheral surface of the photosensitive drum 9 is the yellow (Y) toner contained in the developing container 10c. The toner image thus formed on the peripheral surface of the photoconductor drum 9 reaches the position of the transfer device 10d as the photoconductor drum 9 rotates in the direction of the arrow, and the region directly below the photoconductor drum 9 in the direction of the arrow. Transferred to moving paper.

On the other hand, the sheet is transported by the sheet cassette 11, the standby roll 12, the transport belt 13, the drive roll 14 and the like, which constitute the above-mentioned sheet feeding section 4, and is fed by the rotation of the sheet feeding roller 28. The sheet carried out from the cassette 11 is sent to the standby roll 12, and further, is sent to the transfer belt 13 at a timing matching the toner image, and reaches the transfer device 10d. Then, the toner image is transferred by the transfer device 10 d, and the sheet on which the toner image is transferred moves on the conveyor belt 13 in the direction of the arrow in accordance with the movement of the conveyor belt 13, and is subjected to thermal fixing processing by the fixing unit 15.

Further, on the upper surface of the paper, not only the yellow (Y) toner image but also the drum set C of another color is formed.
1 and the toner image of magenta (M) and cyan (C) transferred by the toner set C2 are also transferred, and the color printing according to the subtractive color mixing described above is performed.

The above-mentioned paper includes not only the paper delivered from the paper feed cassette 11 but also the paper supplied from the MPF tray 16. In this case, the paper is the paper feed roller 16a.
The print processing is performed by the above-mentioned route. Further, the fixing unit 15 includes a heat roll 15a,
15b and a cleaner 15c. While the paper P is nipped and conveyed between the above-described thermal rolls 15a and 15b, the toner images of, for example, a plurality of colors transferred to the paper are melted and the paper P is melted.
Heat fix to. Further, the cleaner 15c is the heat roll 15a.
It has a function of removing the toner remaining in the toner. Note that the sheet on which the toner image is fixed by the fixing unit 15 is the switching plate 17
The sheet is conveyed upward through the paper or leftward on the paper surface.

On the other hand, the double-sided printing transport unit 3 is constructed so as to be attachable to and detachable from the main body of the apparatus.
This is a unit to be mounted when performing double-sided printing, and a plurality of transport rolls 18a to 18e are arranged inside. In the case of double-sided printing, the sheet is once fed upward by the switching plate 17, and, for example, the trailing edge of the sheet is fed to the transport roll 1.
When the number reaches 9, the conveyance of the sheet is stopped and the sheet is conveyed in the reverse direction. By this control, the paper is conveyed downward on the left side of the switching unit 17 set to the position shown by the dotted line, is carried into the paper conveyance path of the double-sided printing conveyance unit 3, and is conveyed by the conveyance rolls 18a to 18e. When it reaches the standby roll 12, it is sent to the transfer device at the same timing as the toner image as described above, and the toner image is transferred to the back surface of the paper.

Next, FIG. 2 is a diagram for explaining a drive mechanism of the photosensitive drum 9 provided in each image forming unit in the printer device 1 having the above-mentioned configuration. In the figure, the photosensitive drum 9 is driven by a plurality of gears. For example,
The photosensitive drum 9M provided in the magenta (M) image forming unit 5 is driven by the drum gear 9m, and the photosensitive drum 9C provided in the cyan (C) image forming unit 6 is driven by the drum gear 9c. . Similarly, the photoconductor drums 9Y and 9K arranged in the image forming units 7 and 8 for yellow (Y) and black (K), respectively.
Are driven by corresponding drum gears 9y and 9k, respectively.

The four drum gears 9m, 9c,
9y and 9k are motor gears 30 of the main motor (not shown)
The driving force is transmitted from the gear mechanism 31 through the gear mechanism 31 and rotates in a predetermined direction. FIG. 3 is an enlarged view of the gear mechanism 31. Drum gears 9m, 9c, 9y, 9k shown in FIG.
Are the corresponding photoconductor drums 9M, 9C, 9Y, 9K.
The drum gear 9 (not shown in FIG. 3) is provided.
When m, 9c, 9y and 9k are rotated, the corresponding photosensitive drums 9M, 9C, 9Y and 9K are also rotated. Further, 30 is a motor gear directly connected to a main motor (not shown).

When the main motor (not shown) rotates, the motor gear 30 rotates clockwise (clockwise) as indicated by the arrow in the figure. By the rotation of this motor gear 30,
The driving force transmission gear (hereinafter, simply referred to as a transmission gear) 32 rotates counterclockwise (rotates counterclockwise) and transmits the rotational force to the transmission gears 33 and 34 meshing with the transmission gear 32.

The transmission gear 33 is a gear for transmitting a turning force to the black (K) photosensitive drum 9K (drum gear 9k) side, and the transmission gear 33 is rotated clockwise.
This rotational force is transmitted to the main body gear 35. Therefore, the main body gear 35 rotates counterclockwise to rotate the above-described drum gear 9k and rotate the photosensitive drum 9K clockwise.

Further, the transmission gear 34 is a photosensitive drum 9M, 9 arranged in an image forming unit other than black (K).
A transmission gear for driving C and 9Y, and a transmission gear 3
4 rotates in the clockwise direction, so that the transmission gear 3
6 is rotated counterclockwise, and the transmission gear 37 is further rotated clockwise.

On the other hand, 38 is a gear with a clutch, and the engagement / disconnection of the gear 38 with a clutch is controlled by driving a solenoid (not shown). The state shown in FIG. 3 shows a state in which the rotational driving force is transmitted to the transmission gear 39 via the gear 38 with the clutch.

With the clutch-equipped gear 38 connected, the clutch-equipped gear 38 rotates the transmission gear 39 in the clockwise direction. Therefore, the transmission gears 40 and 41 meshing with the transmission gear 39 both rotate counterclockwise. The rotation of the transmission gear 40 causes the transmission gear 42 to rotate.
Also rotates, the main body gear 43 rotates counterclockwise to rotate the drum gear 9y described above, and the photosensitive drum 9Y rotates clockwise.

The rotation of the transmission gear 41 in the counterclockwise direction causes the transmission gear 44 to rotate in the clockwise direction, and the drum gear 9c (photosensitive drum 9C) via the main body gear 45.
Rotate clockwise. Further, the transmission gear 46 is rotated by the clockwise rotation of the transmission gear 44, and the drum gear 9m (photosensitive drum 9M) is rotated clockwise through the transmission gear 47 and the main body gear 48.

Therefore, only the photosensitive drum 9K (drum gear 9k) is rotated by rotating the main motor and setting the clutch gear 38 in the disengaged state (disconnected state), and the clutch gear 38 is engaged. To set the photosensitive drums 9M, 9C, 9Y, 9K
(Drum gears 9m, 9c, 9y, 9k) rotate.

On the other hand, a mark 35a is provided on the main body gear 35.
Is provided, and the mark 35a is provided near the main body gear 35.
A sensor 35b for detecting the is provided. Similarly, a mark 9ka is also provided on the drum gear 9k side, and a sensor 9kb for detecting the mark 9ka is provided near the drum gear 9k.

Similarly, a mark 43a is provided on the main body gear 43, and a sensor 43b for detecting the mark 43a is provided near the main body gear 43. A mark 9ya is also provided on the drum gear 9y, and a sensor 9yb for detecting the mark 9ya is provided near the mark.

On the other hand, FIG. 4 is a diagram for explaining the circuit configuration of the printer device 1 of this example. The printer device 1 is an interface (I / F) controller 50, a printer controller 51, a printer printing section 52, a CPU 53, and a ROM 5.
4, an EEPROM 55, and an operation panel 56.

The I / F controller 50 analyzes print data supplied from a host device (not shown), converts it into bitmap data, and stores it in a frame memory. The frame memory has storage areas of the above-mentioned bitmap data for yellow (Y), magenta (M), cyan (C), and black (B), respectively, and stores bitmap data of colors corresponding to each area.

The CPU 53 controls printing according to a program stored in the ROM 54, and outputs the bitmap data stored in the I / F controller 50 to the printer printing section 52 via the printer controller 51.
Incidentally, the EEPROM 55 stores correction data, which will be described later, and is used when the phase of the drum gear is adjusted. The operation signal from the operation panel 56 is supplied to the CPU 53, and the control instructed by the user is performed. In the above configuration, the phase adjustment of the gear of this embodiment will be described below.

First, the positional relationship between the main body gear and the drum gear will be described with reference to FIG. The main body gear 35 has, for example, 96 gear teeth, and the drum gear 9k has, for example, 56 gear teeth. The position shown in FIG. 9A is the home position of both gears. In this home position, the mark 35a of the main body gear 35 is located at the position of the sensor 35b, and the mark 9ka of the drum gear 9k is located at the position of the sensor 9kb.

FIG. 3B shows the main body gear 35 and the drum gear 9 when the drum gear 9k makes one revolution from the start position.
The positional relationship of k is shown. In this state, the position of the mark 35a of the main body gear 35 is still 1 due to the number of teeth of the gear.
It is in a position that does not rotate. Next, further rotate, the same figure (c)
At the position shown in (1), the main body gear 35 has rotated once, but the drum gear 9k is at a position displaced from the initial position. Further, FIG. 7D shows a state in which the drum gear 9k has rotated once next,
Also in this case, the main body gear 35 is not in the initial position.

The movements of the main body gear 35 and the drum gear 9k have a relationship between the main body gear and the drum gear in black (K), but have the same relationship with the main body gear 43 of yellow (Y) and the drum gear 9y. Also, black (K)
Between yellow and yellow (Y) when the clutch is connected,
Usually the phases do not match. Therefore, for example, when the black (K) main body gear 35 and the drum gear 9k are in the position of FIG. 5A, the yellow (Y) main body gear 43 and the drum gear 9y may be in the position of the same figure (b). In some cases, they may be located at positions (c) and (d) in the same figure, and in other positions.

Therefore, when the monochrome mode is changed to the color mode, the deviation amount of the main gear 43 of yellow (Y) from the home position of the main gear 35 of black (K) and the yellow (Y) from the home position of the drum gear 9k. The amount of deviation of the drum gear 9y is measured and the phase is adjusted.

First, color printing is performed using, for example, yellow (Y), magenta (M), cyan (C), and black (K) image forming units. In this case, the clutch-equipped gear 38 and the transmission gear 39 are connected, and as described above, the rotational force of the motor gear 30 is also transmitted to the respective drum gears 9m, 9c, 9y via the clutch-equipped gear 38, and the respective photosensitive drums 9M, Color printing is performed by rotating 9C, 9Y, and 9K.

Next, when the color printing mode is switched to the monochrome mode, the clutch gear 38 is disengaged from the transmission gear 39. By this process, the motor gear 3
The driving force of 0 is transmitted only to the black (K) drum gear 9k, and the rotation of the yellow (Y), magenta (M), and cyan (C) photosensitive drums 9M, 9C, and 9Y is stopped.

After that, when monochrome printing is performed and color printing is performed again, the clutch is reconnected. At this time, as described above, the rotational force of the motor gear 30 is also transmitted to the drum gears 9m, 9c, 9y via the gear 38 with the clutch, and the photosensitive drums 9M, 9C, 9Y also start to rotate.
However, at this time, the phases of the black (K) main body gear 35 and the drum gear 9k do not match the phases of the yellow (Y) main body gear 43 and the drum gear 9y.

Therefore, the marks provided on the main body gears 35 and 43 and the drum gears 9k and 9y are detected by the corresponding sensors and the phase is controlled. That is, the time t1 from the detection of the mark 35a by the sensor 35b to the detection of the mark 43a by the sensor 43b in the color mode is measured. Further, the time t2 from the detection of the mark 9ka by the sensor 9kb to the detection of the mark 9ya by the sensor 9yb is measured. Then, based on the information of the times t1 and t2, the time until the clutch is connected is calculated using an arithmetic expression (not shown).

Next, for example, a value α determined for each model is added to the above result to obtain the clutch switching time. After that, the clutch-equipped gear 38 is disengaged, and the clutch-equipped gear 38 is turned on again after waiting for the switching time. In the present example, the switching time is changed because it further changes due to deterioration of the clutch plate, familiarity and the like. In this example, the adjustment value is stored in the EEPROM 50 and adjustment is performed in response to deterioration of the clutch plate caused by repeating the printing process. Hereinafter, four examples will be described.

First, in the first example, when changing from the monochrome mode to the color mode, the error is measured by the above method and added to the value of α to obtain α + Δα1. Similarly, when the monochrome mode is changed to the color mode next time, the error is measured to be α + Δα1 + Δα2.
This data (Δα1 and Δα1 + Δα2 data)
Is written in the EEPROM 55, but the data is overwritten and updated. Therefore, the latest data read from the EEPROM 55 can be used as the switching timing of the gear 38 with the clutch used in the conversion processing from the monochrome mode to the color mode.

Therefore, by adjusting the connection timing of the clutch-equipped gear 38 in this way, it is possible to take into account the connection delay and so-called familiarity that correspond to the deterioration of the clutch-equipped gear 38. The conversion process to the color mode can be performed. That is, by performing the above processing, it is possible to maintain high clutch engagement accuracy for a long period of time.

Further, in the case of this example, since the data recorded in the EEPROM 55 is sequentially updated, the memory capacity can be small. Next, a second example will be described. The second example is
The configuration is such that the above correction is performed every fixed number of times. That is, when changing from the monochrome mode to the color mode, the error is measured by the above method every time, but the average value is calculated every predetermined number of times, and this average value is added to the value of α, and α
+ Δα

This processing is performed every time the monochrome mode is changed to the color mode a predetermined number of times, and the average value of the error values of 100 times is added to the value of α in correspondence with the mode switching of 100 times, for example. With such a configuration, it is possible to eliminate a delay in connection corresponding to deterioration of the gear 38 with a clutch, so-called familiarity, and the like, and it is possible to maintain high clutch connection accuracy for a long period of time.

Next, a third example will be described. The third example is
Similar to the above, the correction is performed every predetermined number of times, but the error is added to the original value of α. That is, (α + Δα) /
n is added. With this configuration as well, it is possible to perform conversion processing corresponding to the familiarity and deterioration of the clutch plate, and it is possible to maintain high clutch engagement accuracy for a long period of time.

Next, a fourth example will be described. In this example, when calculating the average of the error value for each predetermined time, among the measured error. This is a configuration in which the average value is calculated excluding the maximum value and the minimum value. With this configuration, it is possible to perform more accurate phase adjustment.

In each of the above examples, the memory for storing the error is not particularly limited to the EEPROM 55, and any memory that can hold data for a fixed time and can be written and read can be used.

[0049]

As described above, according to the present invention, the error is measured, the average value is calculated every time or every fixed number of times, the average value is stored in the memory, and is read out at the time of switching to the color mode. It is possible to maintain the clutch switching timing accurately for a long period of time by using the same.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus of this embodiment.

FIG. 2 is a diagram illustrating a gear mechanism of the image forming apparatus according to the present exemplary embodiment.

FIG. 3 is a diagram illustrating details of a gear mechanism of the image forming apparatus according to the present exemplary embodiment.

FIG. 4 is a diagram illustrating a control circuit of the image forming apparatus according to the present exemplary embodiment.

FIG. 5 is a diagram illustrating a positional relationship between a main body gear and a drum gear.

[Explanation of symbols]

1 Printer Device 2 Image Forming Unit 3 Double-sided Printing Conveying Unit 4 Paper Feeding Units 5-8 Image Forming Unit 9 Photoreceptor Drums 9m, 9c, 9y, 9k Drum Gears 9M, 9C, 9Y, 9K Photoreceptor Drum 10a Charger 10b Printing Head 10c Development roll 10d Transfer device 10e Cleaner 10f Eraser 11 Paper feed cassette 12 Standby roll 13 Conveyor belt 14 Drive roll 15 Heat fixing device 15a, 15b Heat roll 17 Switching section 18a to 18e Conveyor roll 30 Motor gear 31 Gear mechanism 32 to 34, 36, 37, 39 to 42, 44, 46, 4
7 Transmission gears 35, 43, 45, 48 Main body gear 38 Clutch gear 50 Interface (I / F) controller 51 Printer controller 52 Printer printing unit 53 CPU 54 ROM 55 EEPROM 56 Operation panel

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/14 G03G 21/00 372 F term (reference) 2H027 DA22 DA39 DE02 DE07 DE10 EB06 EC09 ED02 ED30 EE02 EE07 EE08 EF07 FA28 FA35 2H030 AA01 AB02 AD07 AD17 BB02 BB23 2H035 CA07 CB04 CG01 CG03 2H071 CA02 CA05 DA15 DA26 DA32

Claims (3)

[Claims] 1. A driven gear comprising a first image carrier drum and one or more other image carrier drums, each of which is formed by the same molding process and has a mark and an identical shape. A plurality of image carrier drums arranged in parallel with each other, a first drive transmission mechanism including a marked first drive gear engaged with a driven gear of the first image carrier drum, and A first gear having at least one gear engaged with a driven gear of at least one other image carrier drum and formed by the same molding process as the first drive gear and having a mark and the same shape; A second drive transmission mechanism, a drive source for transmitting a drive force to the first drive transmission mechanism and the second drive transmission mechanism, and a drive source for transmitting the drive force of the drive source only to the first drive transmission mechanism. A first drive transmission mode and a second drive transmitting to both the first and second drive transmission mechanisms The driving force switching means for switching to the reaching mode, the first driving gear detecting means for detecting the home position of the first driving gear through the mark of the first driving gear, and the second driving gear. Second driving gear detecting means for detecting a home position of the second driving gear via a mark, and detecting a home position of the first driven gear via a mark for the first driven gear. First driven gear detection means, second driven gear detection means for detecting a home position of the second driven gear via a mark of the second driven gear, and the first drive transmission First image forming mode executing means for operating the image forming means acting on the first image carrier drum according to the mode, and the plurality of image carrier drums corresponding to the second drive transmission mode. Forming means acting on Second image forming mode executing means for operating the second image forming mode, and in the second image forming mode, after detecting the first driven gear by the first driven gear detecting means,
The time until the second driven gear detection means detects the second driven gear, and the first drive gear detection means detects the first drive gear, and then the second drive gear detection means detects the second drive gear. Measuring means for measuring the switching error of the driving force switching means based on the time until the detection of the second drive gear, storage means for storing the measurement result, and the drive based on the measurement result stored in the storage means. An image forming apparatus comprising: an adjusting unit that adjusts the timing of the force switching unit. 2. The storage means is sequentially overwritten with the error information as the measurement result, and the adjusting means adjusts the switching timing of the driving force switching means using the error information. The image forming apparatus according to claim 1. 3. The storage means stores a predetermined number of error information as the measurement result, and the adjusting means determines the switching timing of the driving force switching means based on an average value of the predetermined number of error information. The image forming apparatus according to claim 1, wherein the image forming apparatus is adjusted.