JP3333360B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for forming an image on a photosensitive drum and transferring the formed image to an intermediate transfer member, and more particularly, to a polygon mirror for one rotation of the intermediate transfer member. And an image forming method in which a rotating member such as a photosensitive drum is rotated an integer number of times.

[0002]

2. Description of the Related Art Conventionally, a technique for rotating a rotary polygon mirror an integer number of times for one rotation of an intermediate transfer member is disclosed in Japanese Patent Laid-Open No. 4-318.
874. In this technology, the relationship between the peripheral length of the photosensitive belt and the intermediate transfer drum is two-to-one, the number of BDT signals when the intermediate transfer drum makes one revolution is set to an integral multiple of the number of surfaces of the rotating polygon mirror, and The rotary polygon mirror is configured to be driven by the same crystal oscillator using a drum motor and a scanner motor configured by using a frequency obtained by arbitrarily dividing the frequency.

[0003]

However, the above-mentioned prior art includes a machine for ensuring that a rotating polygon mirror forms one color image on a photosensitive belt and then forms another color at the same position. The dynamic drive system is not described.

Further, the relationship between the peripheral lengths of the photosensitive belt and the intermediate transfer drum is specified, but no description is given of a mechanical drive system for driving the relationship. Now, if this mechanical drive system is composed of a gear train and the number of teeth is appropriately set as a real number,
When one color is transferred to a photosensitive belt or an intermediate transfer drum, and transfer of a predetermined cycle is completed, and transfer of another color is to be performed,
An image is not transferred to a predetermined place, and there is a possibility that a color shift occurs.

In view of the above circumstances, an object of the present invention is to provide an image forming method which has a simple structure and does not cause color misregistration.

[0006]

According to the present invention, there is provided a polygon mirror which rotates an integer number of times with respect to one rotation of an intermediate transfer member.
In the image forming method for forming an image on the intermediate transfer body, a reduction gear train for driving the intermediate transfer body from a main motor that supplies power to the intermediate transfer body is set to an integer number of teeth corresponding to one rotation of the main motor. Where TM is one rotation time of the intermediate transfer member, TS is one rotation time of the polygon mirror, MG is a reduction gear ratio from the main motor to the intermediate transfer member, MFG is the number of FG pulses of the main motor, and MD is the number of main motor clocks. Assuming that the circumference ratio, FS: polygon motor clock number, SFG: polygon motor FG pulse number, SD: polygon motor clock division ratio, and FM: main motor clock number, the ratio K = TM / TS between TM and TS is obtained. K = (MG / MFG / MD / FS) / (SFG / SD / F
M). Where MFG: main motor FG pal
Is the number of rotations output per shaft rotation of the main motor.
Transfer drum 11, photosensitive drum
It is a drive motor for driving 59A and 59B. Also SF
G: polygon motor FG pulse count means polygon motor
The number of pulses representing the number of rotations output per shaft rotation of
You. Further, FM: Main motor clock number is
Driving based on this clock with the rotation speed reference clock of the motor
A control circuit controls the number of revolutions. Clock generation of FIGS. 2 and 3
The clock transmitted from the generator 32 to the drive control circuit 31
Hit. Further, the drive control circuit is operated by the frequency divider 40A shown in FIG.
This corresponds to a clock sent to the road 31. FIG. 4
(B) is sent to the drive control circuit 31 from the PLL 35A.
Applicable to clock. FS: polygon motor clock
The number is the polygon motor rotation speed reference clock .
A drive control circuit controls the number of rotations based on the lock. Figure
2. From the clock generator 32 in FIG. 3 to the drive control circuit 30
Corresponds to the clock sent. The frequency divider shown in FIG.
Corresponds to the clock sent from 40B to the drive control circuit 31
I do. Further, a drive control circuit is generated by the generator 36 shown in FIG.
This corresponds to the clock sent to 31.

As shown in FIG. 2, the intermediate transfer member 11 is driven from the main motor 12 via a reduction gear train 26A and an intermediate gear 44, and has an integral number of teeth corresponding to one rotation of the main motor. Since the deceleration rate is set to 1/55, the transfer position of the intermediate transfer body 11 is
When the rotation of the motor 12 is stabilized, a signal for image transfer is transmitted according to the rotation speed of the motor 12 and a voltage is applied to the transfer roller 59B. The image is transferred to the predetermined position 11.

The rotation ratio between the photosensitive drum for transferring an image to the intermediate transfer member and the intermediate transfer member is defined as (intermediate transfer member rotation speed NT / photosensitive drum rotation speed NK) = 1/3, or 1 / 2 is preferable. As a result, the contact position of the intermediate transfer member with the photoconductor is always fixed and color shift does not occur, or the ratio of the photoconductor can be made smaller than that of the intermediate transfer member by taking a ratio, so that the cost of the photoconductor can be reduced.

Preferably, a sensor is provided for detecting the start of scanning of the photosensitive drum by the polygon mirror for each scan line, and the intermediate transfer motor is controlled by a signal from the sensor. With this configuration, it is not necessary to form a clock for controlling the intermediate transfer member by dividing the frequency from the basic oscillator, and the intermediate transfer member motor can be controlled at the actual speed of the polygon motor, and a high-quality image without color shift can be obtained. Can be obtained.

Further, the FS and FM are formed from the same basic oscillator, the power to the intermediate transfer member and the photosensitive drum is supplied from the same motor, and the photosensitive member corresponding to one rotation of the intermediate transfer member is supplied. It is preferable to set the rotation ratio of the drum to an integer. The polygon motor and the main motor of the intermediate transfer body are controlled by a clock generated by the basic transmitter, and the photosensitive drum is driven by the same motor (the main motor).
Since the rotation ratio of the photosensitive drum corresponding to one rotation of the intermediate transfer member is set to an integer, the same motor is controlled,
By driving the laser diode in synchronization with the rotation, a plurality of images having different colors are transferred to the same position on the surface of the intermediate transfer member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

FIG. 1 is an external view of an image forming apparatus to which the present invention is applied, FIG. 2 is a block diagram of an embodiment according to the present invention, FIG. 3 is a circuit diagram of a clock generator, and FIG. FIG. 5 is a diagram showing an image of color superposition based on a gear ratio / motor rotation synchronization.

As shown in FIG. 1, an image forming apparatus according to an embodiment of the present invention uses an optical scanning system 1 composed of a polygon mirror 2, a lens system 3, etc. 5, 6 and 7, 8, the photosensitive drum 9
An electrostatic latent image is formed on A and 9B. The photosensitive drum 9A is provided with a black toner developing device 10A and a magenta toner developing device 10B, and the photosensitive drum 9B is provided with a cyan toner developing device 10C and a yellow toner developing device 10D. It is attached.

The surfaces of the photosensitive drums 9A and 9B come into contact with an intermediate transfer sheet 26 (external table) stretched on the intermediate transfer body 11, and the intermediate transfer sheet has a volume resistivity of 10 ¹⁰ to 10 ¹⁴ Ω.
cm in the middle resistance area, thickness 150μm
It is formed of polycarbonate, polyimide, polyetheretherketone or the like.

The photosensitive drums 9A and 9B are developed one by one from the developing unit for each rotation of the drum, and are transferred to the intermediate transfer sheet 26 by Coulomb force. When the transfer of one color is completed, the toner is removed from the photosensitive drum by a cleaner mechanism (not shown), and then the other color is developed on the photosensitive drum. Specifically, a black color is transferred from the photosensitive drum 9A to the intermediate transfer sheet 26, and thereafter, the photosensitive drum 9B
The intermediate transfer sheet 26 rotated to the position shown in FIG.
The cyan color is transferred from B.

After transferring the black color to the intermediate transfer sheet 26, the photosensitive drum 9A removes the residual toner with a cleaner, develops the magenta color, and transfers the magenta color to the intermediate transfer sheet 26. Similarly, after the cyan color is transferred onto the photosensitive drum 9B, the residual toner is removed by a cleaner, and the yellow color is developed and the transfer is performed.

When the four color toners are transferred to the intermediate transfer sheet 26, the paper stored in the paper cassette 14 passes through the passages 16 and 17 by the rollers 15 and the like, and the intermediate transfer sheet 26 and the second transfer roller 19 are transferred. The toner that forms each image is transferred to the sheet, and the transferred sheet is discharged to the transfer device 20 and transferred to the fixing unit 22 by the transfer belt 21. In the fixing unit 22, the image is fixed by the fixing roller 23 and the pressure roller 24,
5 to the outside.

Next, the intermediate transfer drum 11, the photosensitive drum 5
The positional relationship between 9A, 59B and the second transfer roller 19 will be described. In FIG. 1, the rotation ratio between the photosensitive drum that transfers an image to the intermediate transfer body and the intermediate transfer body is configured such that (intermediate transfer body rotation speed NT / photosensitive drum rotation speed NK) = 1/3. .

FIG. 2 is a block diagram of an embodiment according to the present invention. For convenience of explanation, the photosensitive drum 9A and the transfer roller 59A shown in FIG. 1 are removed. Intermediate transfer member 1
1 is gear-coupled to the intermediate gear 44 by a gear (not shown), and the main motor 12 and the reduction gear train 28A reduce the reduction rate between the main-in motor 12 and the intermediate transfer body 11 by 1/55.
Is set to A reduction gear train for driving the intermediate transfer body 11 from the main motor 12 that supplies power to the intermediate transfer body 11 is set to an integer number of teeth corresponding to one rotation of the main motor 12.

From the intermediate gear 44 via a gear train 28B,
The diameter ratio or the rotation ratio between the intermediate transfer body 11 and the photosensitive drum 9B is set to 1/3. The ratio may be set to 1/2. In the vicinity of the photosensitive drum 9B, there is provided a sensor 9Ba for detecting the start of each line for scanning the surface of the photosensitive drum 9B with an optical signal from the laser diode 29 by the polygon mirror 2, so that a pin photo signal can be generated by the sensor. Is configured. The intermediate gear 44 is connected to a photosensitive drum 9A (not shown) and has a sensor for generating a pin photo signal. The photosensitive drum 9A is connected to the photosensitive drum 9B.
It is set under the same conditions as.

The main motor 12 includes the motor 12
Is connected to a clock generator 32, and the clock generator 32 is connected to a polygon motor drive control circuit 30 for controlling the polygon mirror 2. I have. The details of the clock generator 32 will be described later.

A video data writing control circuit 33 having three input terminals is provided, and the pin photo signal, the video signal, and the intermediate transfer drum 11 are connected to those input terminals.
, A detection signal of a position detector 34 that detects a rotation position for one rotation of the intermediate transfer drum 11 is input.

FIG. 3 is a circuit diagram of the clock generator 32. The output terminal of the reference clock generator 36 is connected to one PL.
Intermediate transfer drum drive control circuit 31 via L circuit 35A
And to the polygon motor drive control circuit 30 via the other PLL circuit 35B.
The PLL circuit 35A includes a phase comparison circuit 37A, a low-pass filter 38A, a voltage control oscillator 39A, and a 1 / N frequency divider 4
0A, and the PLL circuit 35B
7B, low-pass filter 38B, voltage control transmitter 39
B, 1 / M frequency divider 40B.

This embodiment has the polygon mirror 2 which rotates an integer number of times with respect to one rotation of the intermediate transfer member 11, and is configured to form an image on the intermediate transfer member 11. Then, a reduction gear train for driving the intermediate transfer member 11 from the main motor 12 that supplies power to the intermediate transfer member 11 is set to an integer number of teeth corresponding to one rotation of the main motor 12,
MG: reduction gear ratio from the main motor to the intermediate transfer member, M
FG : Main motor FG pulse number, MD: Main motor clock division ratio, FS: Polygon motor clock number, S
When FG is the number of FG pulses of the polygon motor, SD is the frequency division ratio of the polygon motor clock, and FM is the number of main motor clocks, TM is one rotation time of the intermediate transfer member, and TS is one rotation time of the polygon mirror. = MG / MFG / MD / FM, TS = SFG / SD / FS, and the ratio of TM to TS, K = TM / TS, is an integer, and K = (MG / MFG / MD / FS) / (SFG / SD・ F
M)

In this embodiment, the intermediate transfer member 11 is driven from the main motor 12 via the reduction gear train 28A and the intermediate gear 44, and the reduction rate of the integral number of teeth corresponding to one rotation of the main motor. Is set to 1/55, the transfer position of the intermediate transfer body 11 can be controlled by the number of rotations of the main motor 12, and the image is adjusted according to the number of rotations of the motor from the time when the rotation of the motor 12 is stabilized. By transmitting a transfer signal and applying a voltage to the transfer roller 59B, the image is transferred to a predetermined position of the intermediate transfer body 11 with a small amount of displacement.

Generally, the main component of the rotational fluctuation is a repetitive rotational fluctuation, which is combined with non-repetitive rotational fluctuation due to bearing slip, gear engagement, external load and the like. Non-repetitive rotation fluctuation is small if the load is stable, and
The rotation fluctuation when viewed in rotation is small. It is understood from the later-described rotation accuracy measurement data of the intermediate transfer member that the image is transferred at substantially the same position without color shift by setting the above conditions.

FIGS. 4A and 4B show another embodiment of the clock generator. FIG. 4A shows an intermediate circuit from a reference clock generator 36 via a 1 / N divider 40A and a 1 / M divider 40B, respectively. The transfer drum drive control circuit 31 and the polygon motor drive control circuit 30 are connected.

FIG. 3B shows a reference clock generator 36.
Is connected to the polygon motor drive control circuit 30 in FIG. 2, and the pin photo signal in FIG. 2 is sent to the intermediate transfer drum drive control circuit 31 via the PLL circuit 35A. Therefore, when this is applied to FIG. 2, the clock generator 32 and the intermediate transfer drum drive control circuit 3
1 is replaced by a line connected from the sensor 9Ba to the video data writing control circuit 33 to the intermediate transfer drum drive control circuit 31 via the PLL circuit 35A. Things.

With such a configuration, it is not necessary to form a clock for controlling the intermediate transfer member by dividing the frequency from the basic oscillator, and the intermediate transfer member motor can be controlled at the actual speed of the polygon motor, and there is no color shift. High quality images can be obtained.

[0030]

【Example】

[Table 1] When the rotational accuracy of the intermediate transfer body 11 of the present embodiment having the above configuration was measured, data as shown in Table 1 was obtained. When the deviation of the scanning lines of the polygon mirror and the intermediate transfer member is obtained from this data, the deviation of the polygon mirror is (A3 / (1/6) × A2) × C2 × 10 ⁻² × 1/2 ≒ 0.22 ·・ ・ (1) The deviation of the intermediate transfer member is (A3 × C3) /A1≒0.112 (2)

As can be seen from the above (2), the deviation of the intermediate transfer member appears as 43 in a certain direction with respect to the predetermined position 42 as shown in FIG. It is understood that there are few. This value is obtained from the worst case of the rotation fluctuation, and is actually a smaller value. Assuming that the gear ratio is a real number, as shown by reference numeral 44 in FIG.
If you do not synchronize the intermediate transfer drum and the polygon,
It can be seen that a larger deviation occurs as shown in FIG.

[0032]

As described in detail above, the present invention can provide an image forming method with a simple structure and without color shift.

[Brief description of the drawings]

FIG. 1 is an external view of an image forming apparatus to which the present invention is applied.

FIG. 2 is a block diagram of an embodiment according to the present invention.

FIG. 3 is a circuit configuration diagram of a clock generator.

FIG. 4 is a diagram of another embodiment of a clock generator.

FIG. 5 is an image diagram of color superposition based on gear ratio / motor rotation synchronization.

[Explanation of symbols]

Reference Signs List 9 photosensitive drum 11 intermediate transfer drum (intermediate transfer body) 12 drive source 13 cleaner unit 15, 25 roller 19 second transfer roller 20 transport device 22 fixing unit 26 intermediate transfer sheet 28 gear train 29 laser diode 30 polygon motor drive control circuit 31 Intermediate transfer drum drive control circuit 32 Clock generator 33 Video data writing control circuit 34 Position detector 35 PLL circuit

Claims (4)

(57) [Claims] 1. An image forming method, comprising: a polygon mirror that rotates an integer number of times with respect to one rotation of an intermediate transfer member, wherein an image is formed on the intermediate transfer member. The reduction gear train for driving the intermediate transfer member is set to an integer number of teeth corresponding to one rotation of the main motor, TM: one rotation time of the intermediate transfer member, TS: one rotation time of the polygon mirror, and TM and TS. Wherein K = TM / TS is an integer, and the following formula is satisfied. Note K = (MG ・ MFG ・ MD ・ FS) / (SFG ・ SD ・ F
M) MG: reduction gear ratio from the main motor to the intermediate transfer member, MFG : number of main motor FG pulses, MD: main motor clock division ratio, FS: polygon motor clock number, SFG: polygon motor FG pulse number, SD: Polygon motor clock division ratio, FM: number of main motor clocks 2. The method according to claim 1, wherein the rotation ratio between the photosensitive drum for transferring an image to the intermediate transfer member and the intermediate transfer member is (intermediate transfer member rotation speed NT / photosensitive drum rotation speed NK) = 1/3 or 1 /
2. The image forming method according to claim 1, wherein the number is 2. 3. The image according to claim 1, further comprising a sensor for detecting a start of scanning of the photosensitive drum by the polygon mirror for each scan line, and controlling the intermediate transfer body motor based on a signal from the sensor. Forming method. 4. The apparatus according to claim 1, wherein the FS and the FM are formed from the same basic oscillator, and the power to the intermediate transfer body and the photosensitive drum is supplied from the same motor, and the photosensitive element corresponding to one rotation of the intermediate transfer body is provided. 3. The image forming method according to claim 2, wherein the rotation ratio of the drum is set to an integer.