JP2003015375A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device by which the reduction of the costs of an intermediate transfer body and a transfer material carrier and the miniaturization of an entire device are realized by keeping the entire circumference lengths of the intermediate transfer body and the transfer material carrier to an absolute minimum while improving the productivity of a monochromatic image forming mode. SOLUTION: This image forming device has the monochromatic image forming mode in which a monochromatic image is formed at first processing speed by using one kind of toner and a full color image forming mode in which a multicolor image is formed at second processing speed lower than the first processing speed by using the several colors of toner, and is operated at the second processing speed in the case of forming the monochromatic image and the multicolor image on the same surface of the intermediate transfer body or a transfer medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, and more particularly to an image forming apparatus such as a copying machine, a printer or a fax machine having different process speeds in a monochrome mode and a full color mode.

[0002]

2. Description of the Related Art FIG. 11 shows a conventional full-color image forming apparatus. FIG. 11 shows an image forming apparatus using an intermediate transfer body. This apparatus has a photoconductor 101 which is a first image carrier, and a primary charger 10 that uniformly charges the surface of the photoconductor 101 around the photoconductor 101 from the upstream side along the rotational direction.
2. An image exposure device 103 for exposing the photoconductor 101 based on an image signal to form an electrostatic latent image, a developing device 104 for adhering toner to the electrostatic latent image for development, and a color developing device 105 are arranged. There is. In the color developing device 105, three developing devices are arranged on a rotatable rotating body, and the rotating body rotates so that the developing device faces the photoconductor to perform a developing process.

An intermediate transfer member 106, a charge eliminator 110, and a cleaner 109 are arranged as a second image bearing member downstream of the developing position of the photosensitive member 101. A secondary transfer belt unit 107 is arranged downstream of the intermediate transfer member 106, and a bias applying roller 111 is arranged downstream of the secondary transfer belt unit 107. Secondary transfer belt unit 1
Reference numeral 07 designates a secondary transfer belt 107a and a transfer roller 107.
b, a driving roller 107c.

A fixing device 108 is arranged downstream of the secondary transfer belt unit 107 in the paper conveying direction. This fixing device 108 has a pair of rollers 108a and 108b, and a heater 108c built in one or both of them, and the rollers 108a and 108b are pressed against each other at a constant pressure to form a fixing nip. Then, the photoconductor 10
1, the primary transfer high voltage power source 112 (HVT · T1), and the transfer roller 107b the secondary transfer high voltage power source 113 (HVT · T1).
-T2), a high voltage bias power source 114 (HVT / ICL) is connected to the bias applying roller 111.

Next, the image forming process will be described.

By applying an AC bias and a DC bias to the primary charger 102 such as a corona charger or a roller charger, the surface of the photoconductor is uniformly charged to, for example, -550V. Laser or LED on the surface of the charged photoreceptor
When the image pattern is exposed by the image exposure device 103 such as the one described above, the surface potential of the exposed portion on the surface of the photoconductor is attenuated to about −150 V, and a potential difference is generated between the exposed portion and the unexposed portion, so that a static image corresponding to the image pattern is generated. A latent image is formed. By developing the electrostatic latent image in the developing device 104 and the color developing device 105, the negative charging toner adheres to the exposed portion, and a toner image (visible image) is formed.

The intermediate transfer member 106 is a primary transfer portion of the photosensitive member 1.
The primary transfer nip N1 is formed so as to face 01. At the primary transfer portion, the intermediate transfer member 106 is charged with a charge having a polarity opposite to that of the toner by a constant voltage or a constant current. For example, the voltage (primary transfer bias: T1) is increased by the primary transfer high voltage power supply 112.
By applying a constant value of 300 V, the toner image developed on the photoconductor 101 is transferred to the intermediate transfer body 106.

In the full-color image formation, this step is repeated while aligning the toners of a plurality of colors to form an image in which a plurality of colors are overlapped on the surface of the intermediate transfer member 106.

Next, in the secondary transfer portion, the secondary transfer belt unit 107 forms a secondary transfer nip N2 facing the intermediate transfer member 106. A constant voltage or constant current charge is applied to the secondary transfer belt 107a, but a voltage (secondary transfer bias: T2) having a polarity opposite to that of the toner is fixed at a constant value of +1.5 kV by the secondary transfer high-voltage power supply 113, for example. By applying
A toner image of a single color or a plurality of colors charged with a negative polarity on the intermediate transfer body 106 is printed on a recording medium such as paper (hereinafter,
It is referred to as paper, recording paper, transfer material, etc.) P. Further, the surface of the secondary transfer belt 107a is positively charged by the secondary transfer bias, so that the recording medium P is adsorbed and conveyed and sent to the fixing device 110.

The fixing device 108 includes a pair of rollers 108a,
108b has a heater built in one or both of them, or a heating means 108c from the outside.
The a and 108b are pressed against each other at a constant pressure. The recording medium P is the rollers 108a and 108b of the fixing device 108.
When passing through the space, the toner image is fixed on the recording medium P at the same time as color mixing due to heat and pressure, and a full-color image is obtained.

The image forming apparatus is, for example, a full-color printer capable of outputting to A3 paper, and since the entire circumference of the intermediate transfer member 106 is prepared to be longer than the length of the A3 paper in the long side direction, it is smaller than A3. For example, when outputting to A4 paper, it is possible to form an image of two pages on the same surface of the intermediate transfer body 106.

In such an image forming apparatus, in which a full-color image is obtained by sequentially repeating the formation of toner images of a plurality of colors and the primary transfer to the intermediate transfer member 106 on the photosensitive member 101 as one image carrier. When the process speed of the color image forming mode and the process speed of the full color image forming mode using four color toners are the same, the productivity of black-and-white output is only up to four times the productivity of full color output.

In order to solve the above problem, Japanese Patent Laid-Open No. 10-177
In the invention described in Japanese Patent No. 283, a method is proposed in which the process speed in the monochrome mode is made higher than that in the full color mode.

[0014]

However, the above solution has the following problems when continuously outputting a monochrome image and a full-color image.

In continuous output, for example, in the case of performing full-color image formation after black-and-white image formation, it is necessary to change the speed of the drive motor in order to slow down the rotation speed of the image bearing member such as the photosensitive member or the intermediate transfer member. When a single laser scanning unit is used for image exposure, it is necessary to shift the scanner motors, and a waiting time is required until the rotation of these motors becomes stable.

Further, it is necessary to change the primary charging setting of the photoconductor as the photoconductor is shifted, and it is necessary to perform a pre-rotation of about one revolution of the photoconductor until the charge potential of the photoconductor becomes stable.

When the process speed of the first page and the second page is changed when forming the image of the second page on the same surface of the intermediate transfer member, the waiting time and the pre-rotation are between the first page and the second page. Will be installed in. That is, it is necessary to increase the total circumferential length of the intermediate transfer member required to form an image of two pages.

Further, Japanese Patent Laid-Open No. 8-320608 proposes a method of increasing the process speed after the secondary transfer in the single color and slowing it in the full color, but the black and white image formation is performed after the full color image formation. In this case, when the black-and-white image is transferred at a high process speed after the full-color image is transferred in the transfer step, the transferred material on which the black-and-white image has been transferred is transferred onto the transferred material on which the full-color image has been transferred. It catches up with the transfer material. In order to avoid this, it is necessary to secure a sufficient space between sheets, but in that case as well, the entire circumference of the intermediate transfer member must be increased.

The present invention has been made to solve the above-mentioned problems, and minimizes the total circumference of the intermediate transfer member and the transfer material carrying member while improving the productivity of the monochromatic image forming mode. An object of the present invention is to obtain an image forming apparatus which realizes cost reduction of an intermediate transfer member and a transfer material carrying member and downsizing of the entire device.

[0020]

The present invention is an image forming apparatus having the following configuration.

(1) At least one photoconductor, a plurality of developing devices that develop with a plurality of toners of different colors to form a toner image on the photoconductor, and image formation of two or more pages in the same plane. An intermediate transfer member having a possible entire circumference, a primary transfer unit for transferring the toner image formed on the photosensitive member to the intermediate transfer member, and a toner image for transferring the toner image on the intermediate transfer member to a transfer material. A mono-color image forming device that includes a secondary transfer unit and a fixing unit that fixes the toner image transferred to the transfer material onto the transfer material, and that forms a single-color image at a first process speed using one type of toner. There are an image forming mode and a full-color image forming mode for forming a multicolor image at a second process speed lower than the first process speed by using toners of a plurality of colors, and in the same plane of the intermediate transfer member. Single-color images and multi-color images If you formed the image forming apparatus characterized by operating in the second process speed.

(2) At least one photoconductor, a plurality of developing devices that develop with a plurality of toners of different colors to form a toner image on the photoconductor, and image formation of two or more pages in the same plane. An intermediate transfer member having a possible entire circumference, a primary transfer unit for transferring the toner image formed on the photosensitive member to the intermediate transfer member, and a toner image for transferring the toner image on the intermediate transfer member to a transfer material. A mono-color image forming device that includes a secondary transfer unit and a fixing unit that fixes the toner image transferred to the transfer material onto the transfer material, and that forms a single-color image at a first process speed using one type of toner. An image forming mode and a full-color image forming mode for forming a multicolor image by performing at least secondary transfer and fixing at a second process speed slower than the first process speed using toners of a plurality of colors are provided. , The intermediate transfer The image forming apparatus when forming a monochrome image and a color image in the same plane of the body which is characterized in that the fixing and the secondary transfer by the second process speed.

(3) At least one photoconductor, a plurality of developing devices for developing a plurality of toners of different colors to form a toner image on the photoconductor, and a transfer material having two or more pages in the same plane. And a transfer material carrier having an entire perimeter capable of transporting the toner image formed on the photoconductor to the transfer material, and fixing the toner image transferred to the transfer material to the transfer material. A mono-color image forming mode that includes a fixing unit and forms a single-color image at a first process speed using one type of toner, and a second process that uses toners of a plurality of colors and is slower than the first process speed. It has a full-color image forming mode for forming a multi-color image at a speed, and is the second when forming a single-color image and a multi-color image on the same surface of the transfer material carrier.
An image forming apparatus that operates at the process speed of.

(4) At least one photoconductor, a plurality of developing devices that develop with a plurality of toners of different colors to form a toner image on the photoconductor, and a transfer material having two or more pages in the same plane. And a transfer material carrier having an entire perimeter capable of transporting the toner image formed on the photoconductor to the transfer material, and fixing the toner image transferred to the transfer material to the transfer material. A mono-color image forming mode that includes a fixing unit and forms a single-color image at a first process speed using one type of toner, and a second process that uses toners of a plurality of colors and is slower than the first process speed. It has a full-color image forming mode for forming a multi-color image by fixing at a speed, and when forming a single-color image and a multi-color image on the same surface of the transfer material carrier, the fixing is performed at a second process speed. Image shape characterized by doing Apparatus.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.

[Embodiment 1] In the embodiment of the present invention, a full-color laser beam printer using a negative process will be described. Figure 1 shows a full-color laser beam printer (or copier) that uses an intermediate transfer body.
2 is a schematic cross-sectional view of FIG.

The apparatus is equipped with a photoconductor 1 as a first image carrier. This photoconductor 1 rotates in the direction of the arrow, and a primary charger 2 that uniformly charges the surface of the photoconductor 1 from the upstream side to a negative polarity, and exposes the photoconductor 1 based on an image signal to form an electrostatic latent image. A laser exposure device 3, a developing device 4 for adhering toner to the electrostatic latent image for development, and a color developing device 5 are arranged. In the color developing device 5, three developing devices are arranged on a rotatable rotating body, and the rotating body rotates to allow the developing device to face the photoconductor to perform a developing process.

An intermediate transfer member 6, a static eliminator 10, and a cleaner 9 are arranged as a second image bearing member downstream of the developing position of the photosensitive member 1. The intermediate transfer member 6 is cylindrical and has a drum shape or a belt shape made of rubber, elastomer, resin or the like. A secondary transfer belt unit 7 is arranged downstream of the intermediate transfer body 6, and a bias applying roller 11 is arranged downstream of the secondary transfer portion. The secondary transfer belt unit 7 includes a secondary transfer belt 7a, a transfer roller 7b, and a driving roller 7c.

A fixing device 8 is arranged downstream of the secondary transfer belt unit 7 in the paper conveying direction. This fixing device 8 has a heater 8c built in one or both of a pair of rollers 8a and 8b, and the rollers 8a and 8b are pressed against each other at a constant pressure to form a fixing nip. A primary transfer high voltage power supply 12 (HVT · T1) as a primary transfer means is provided on the photoconductor 1, and a secondary transfer high voltage power supply 13 (HVT · T) as a secondary transfer means is provided on the transfer roller 7b.
2) The high voltage bias power supply 14 (HVT / ICL) is connected to the bias applying roller 11.

In this embodiment, yellow (Y), magenta (M) and cyan (C) toners are used in the color developing device 5,
Black toner (K) was used for the developing device 4. The process speed is set to 200 mm / sec in the mono-color mode in which a single color image is obtained by using only one of these toners, and the process speed is 100 mm in the full-color mode in which a multi-color image is obtained by using a plurality of these toners. / Se
c.

The image forming apparatus of this embodiment is controlled by a controller (not shown). In the case of a printer, the controller expands the data sent from a host such as a personal computer and sends it to the printer engine, or in the case of a copying machine, it performs predetermined image processing on the image read from the platen and sends the data to the printer engine. Is the part to send. The engine can switch the operation by sending a machine-specific signal indicating whether the color mode operated when the controller sends the image data to the printer engine is the full color mode or the monocolor mode.

In this embodiment, A is formed on the same surface of the intermediate transfer member 6.
It is possible to form two pages of four sizes, and the present invention is realized by sending color mode information up to two pages ahead from the controller when outputting a plurality of prints.

The flowchart is shown in FIG.

In the full-color mode, for example, the surface of the photoconductor 1 is uniformly charged to −550 V by the primary charger 2, and then an image pattern is exposed by the laser exposure device 3 to form an electrostatic latent image. The exposed surface of the photoconductor 1 has an unexposed partial potential (VD) of -550V and an exposed partial potential (VL) of -150V. When a developing bias of −350 V is applied to the developing sleeves of the developing unit 4 and the color developing unit 5, the VL portion of the photoconductor 1 having a low surface potential is developed with a negatively-charged negative toner, and the electrostatic latent image is visualized. Image.

The intermediate transfer member 6 also serves as a first transfer member and rotates at a substantially constant speed with the photosensitive member 1. Intermediate transfer member 6
When a primary transfer bias (T1) of +300 V is applied to the core metal by the primary transfer high-voltage power supply 12, the toner image on the photoconductor 1 is transferred between the VL portion of the photoconductor 1 and the intermediate transfer body 6 at the primary transfer nip portion N1. It is transferred to the intermediate transfer member 6 by the potential difference of 450V. By repeating the above steps for four color toners of yellow (Y), magenta (M), cyan (C), and black (K), an image in which four color plates are overlapped is formed on the intermediate transfer member 6.

Next, the secondary transfer belt 7a is pressed against the intermediate transfer body 6 to form the secondary transfer nip N2, and in synchronization with the image front end on the intermediate transfer body 6, a recording medium such as paper (hereinafter referred to as paper,
A recording paper, referred to as a transfer material, etc.) P is fed into the secondary transfer nip. Then, the secondary transfer high voltage power supply 13 applies a secondary transfer bias (T2) to the secondary transfer belt 7a by +1.5 k.
When V is applied, the toner image is transferred to the recording medium P.
The recording medium P on which the toner image is transferred is sent to the fixing device 8. The recording paper P is a pair of rollers 8a and 8b of the fixing device 8.
When passing through the space, the toner image is fixed on the paper P at the same time as color mixing due to heat and pressure, and a full-color image is obtained. Figure 2
The operation sequence and the rotation speed of the intermediate transfer member 6 are shown in FIG.

In the mono-color mode, the primary charging, developing conditions, primary transfer, secondary transfer conditions, etc. are optimized in accordance with the increase in the process speed. Then, the steps of primary charging, development, and primary transfer are performed only for one kind of toner. FIG. 3 shows the operation sequence and the rotation speed of the intermediate transfer member 6.

In this embodiment, the photosensitive member 1 has a diameter of 60 mm and the intermediate transfer member 6 is a drum-shaped intermediate transfer drum having a diameter of 180 mm. The peripheral length of the intermediate transfer member 6 is 567 mm, and it is possible to form an image for two pages of letter (LTR) size (8.5 × 11 inches) in the same plane. When the paper interval (L1) of each page during continuous output is 45 mm and the letter size image area is 216 mm, 567-45-216 × 2 = 90 mm The remaining 90 mm, that is, 0.9 seconds, is the same as when outputting in full color mode. It is used as the switching time of the color developing device 5a, that is, the distance (L2) that the intermediate transfer member 6 advances.

In this embodiment, when a full-color image and a black-and-white image are continuously formed on the same surface of the intermediate transfer member 6, the process speed of the mono-color mode is the same as that of the full-color mode.
It was set to 00 mm / sec. The sequence and the rotation speed of the intermediate transfer member 6 are shown in FIG. For example, when the apparatus main body receives an image signal of one full-color image and one black-and-white image, the main motor rotates at 100 mm / sec, and the first full-color image is subjected to primary charging, image exposure for each color of yellow, magenta, and cyan. Development and primary transfer steps are performed.

Next, at the same process speed, the black of the first full-color image and the black of the second black-and-white image are successively subjected to the primary charging, development and primary transfer steps. As a result, a full-color image and a monochrome image are formed on the intermediate transfer member 6. Next, the secondary transfer belt 7a is brought into contact with the intermediate transfer member 6, a secondary transfer nip N2 is formed, a transfer bias is applied from the secondary transfer high-voltage power supply 13, and two recording materials P are continuously formed. Then, each image is transferred to the recording material P.

As shown in FIG. 5, without using the present invention, the intermediate necessary for the conventional method of continuously forming a black-and-white image and a full-color image on the same surface of the intermediate transfer member 6 at different process speeds. The circumference of the transfer body 6 is calculated below. The diameter of the photoconductor 1 is also set to 60 mm, and the distance (L2) that the intermediate transfer body 6 advances during rotation of the rotary member necessary for switching the color developing device 5 in the full color mode is also set to 90 mm.

Process speed 100 mm / sec to 200 mm
In order to stabilize the potential of the photoconductor 1 after switching to / sec, the moving distance of the intermediate transfer body 6 required when the photoconductor 1 is rotated once is 60π = 188 mm. The peripheral length of the intermediate transfer member 6 required to form two letter size pages under the condition that the distance between two pages (L1) is the above value is LTR × 2 + L1 + L2 = 216 × 2 + 188 + 90 =
It is 710 mm (φ226 mm).

The productivity of the image forming apparatus using the intermediate transfer member 6 having the above-mentioned circumference is calculated below.

In the full color mode, the intermediate transfer member 6
The number of rotations is (100 mm / sec × 60 sec) ÷ 710 = 8.45 revolutions / minute, and two full-color images can be output every four revolutions of the intermediate transfer member 6. Therefore, 8.45 ÷ 4 × 2 = about 4.2 sheets / minute.

In black and white mode, page spacing (paper interval) is 45 mm
(200 mm / sec × 60 sec) ÷ (216 + 45) = approx. 46
Calculated as sheets / minute.

On the other hand, according to the present embodiment, the productivity when the peripheral length of the intermediate transfer member 6 can be reduced is (100 mm / sec × 60 sec) ÷ 567 = 10.58 revolutions /
Since it is possible to output two full-color images every four rotations of the intermediate transfer member 6, 10.58 ÷ 4 × 2 = about 5.29 sheets / min, which improves the productivity of full-color output. It has become possible.

[Second Embodiment] Another embodiment will be described below.

An explanatory view of the image forming apparatus in this embodiment is shown in FIG. In this embodiment, the transfer drum 2 having a circumference of 577 mm
In this example, 0 is used as the transfer material carrier, and the primary charging, image exposure, development, and transfer steps are performed at a process speed of 200 mm / sec. The same in monochrome mode (Fig. 8) 20
The fixing step is performed at a process speed of 0 mm / sec. Further, in the full-color mode (FIG. 9), the fixing step is performed at a process speed of 140 mm / sec in order to secure the fixability of multicolor toners.

In this embodiment, when two transfer materials P are adsorbed on the same surface of the transfer drum 20 to continuously form a full-color image and a black-and-white image (FIG. 9), the fixing process speed is set to the full-color mode. The same as 140 mm / sec. For example, when the apparatus main body receives an image signal of one full-color image and one black-and-white image, the main motor rotates at 200 mm / sec, and the first full-color image is subjected to primary charging, image exposure for each color of yellow, magenta, and cyan. Develop and transfer process.

Next, at the same process speed, the black of the first full-color image and the black of the second black-and-white image are successively subjected to primary charging, development and transfer steps. As a result, a full-color image and a black-and-white image are formed on the transfer material P on the transfer drum 20, respectively. Next, the process speed is reduced to 140 mm / sec, the transfer material P is separated from the transfer drum 20, and sent to the fixing device 8.

Without using the present invention, the first sheet is full color,
In the case of the conventional method in which a black and white image is formed on the second sheet and the fixing process speeds are changed (FIG. 10), the transfer material P onto which the second black and white image is transferred is the first full color image. It is necessary to set an interval between the transfer target material P and the transferred material P so that they will not catch up before being discharged.

For example, the distance from transfer to discharge is 200 m
In the case of m, the time until the trailing edge of the transfer material P on which the first full-color image transferred, which is conveyed at 140 mm / sec, is discharged after the transfer is 1.43 seconds. On the other hand, the time until the second transfer target material P on which the black and white image is transferred, which is conveyed at 200 mm / sec, is discharged after the transfer is 1
Since it is seconds, it is necessary to provide a paper interval of 0.43 seconds or more corresponding to the difference between the two.

If the conveying speed of the second sheet is 200 mm / sec, a sheet interval (L1) of 86 mm is required. Color developing device 5
The distance traveled by the intermediate transfer member 6 during switching is 100 mm (L2) when an image is formed at 200 mm / second when the switching time is 0.5 seconds. Letter size (LT
R) The peripheral length of the transfer drum 20 required to form two sheets is LTR × 2 + L1 + L2 = 216 × 2 + 86 + 100 =
618 mm (φ197 mm).

On the other hand, when the present invention is used, the paper interval (L
1) can be further reduced, and when the peripheral length of the transfer drum 20 is 45 mm, which is equivalent to that of the first embodiment, the peripheral length of the transfer drum 20 is LTR × 2 + L1 + L2 = 216 × 2 + 45 + 100 =
It is 577 mm (φ184 mm).

Transfer drum 20 during full-color image formation
Forms a full-color image by rotating four times. Therefore, reducing the peripheral length of the transfer drum 20 is effective in shortening the first print time. For example, in the above example, 618 mm at a process speed of 140 mm / sec.
The time required for the transfer drum 20 to rotate 4 times is 4.4 seconds, while the time required for the transfer drum 20 of 577 mm to rotate 4 times is 4.
1 second, about 0.3 without increasing the process speed
Second First print output time can be shortened.

In this embodiment, the full-color mode and the black mode are described as an example. However, the full-color mode is changed to a multi-color mode in which two or more developing devices such as red and blue are operated to output. The present invention is also effective when performing monochrome color printing such as yellow, magenta, and cyan in place of the black mode.

[0057]

As described above, according to the present invention, 1
A monocolor image forming mode in which a single color image is formed at a first process speed using different types of toner, and a multicolor image is formed at a second process speed that is slower than the first process speed using a plurality of color toners. In the case of having a full-color image forming mode for forming and forming a single-color image and a multi-color image on the same surface of an intermediate transfer body or a transfer medium, it is configured to operate at the second process speed. The problem of mixed image loading has been solved, and the intermediate transfer member or transfer material carrying member can be downsized. As a result, it is possible to reduce the cost of the intermediate transfer member or the transfer material carrier and reduce the size of the main body. Further, there is an effect that productivity of full-color printing and reduction of time for first printing can be realized without increasing the process speed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of full color mode operation according to the first embodiment.

FIG. 3 is an explanatory diagram of a monocolor mode operation according to the first embodiment.

FIG. 4 is an explanatory diagram of full-color and monochrome continuous mode operation according to the first embodiment.

FIG. 5 is an explanatory diagram of a conventional full-color, monochrome continuous mode operation.

FIG. 6 is a schematic sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of full color mode operation according to the second embodiment.

FIG. 8 is an explanatory diagram of a monocolor mode operation according to the second embodiment.

FIG. 9 is an explanatory diagram of full-color and monochrome continuous mode operation according to the second embodiment.

FIG. 10 is an explanatory diagram of a conventional full-color, monochrome continuous mode operation.

FIG. 11 is a schematic sectional view of a conventional image forming apparatus.

FIG. 12 is a flowchart in the first embodiment.

[Explanation of symbols]

1 photoconductor 2 Primary charger 3 exposure device 4 Black developer 5 color developer 6 Intermediate transfer body 7 Secondary transfer member 8 fixing device 12 Primary transfer high-voltage power supply (primary transfer means) 13 Secondary transfer high-voltage power supply (secondary transfer means) 20 transfer drum 21 Transfer charger 22 Adsorption charger 23 Separation charger

Continued front page    F-term (reference) 2H027 DA06 DA07 DA17 DA18 DA18 DA20                       DE01 DE07 DE09 EA01 EA03                       EA04 EB04 EC06 EC09 EC20                       ED02 ED03 ED08 ED24 ED25                       EE03 EE04 EE07 FA28 FA35                 2H030 AD02 AD04 AD05 AD07 AD08                       AD16 BB12 BB32 BB42 BB43                       BB52 BB63                 2H200 FA20 GA23 GA29 GA30 GA44                       GA47 GB21 GB30 HA01 HA28                       HB01 HB12 JA01 JA29 JA30                       JB06 JC03 JC19 JC20 PA10                       PA11 PA26 PB40

Claims (4)

[Claims] 1. At least one photoconductor, a plurality of developing devices that develop with a plurality of toners of different colors to form a toner image on the photoconductor, and image formation of two or more pages in the same plane is possible. An intermediate transfer member having a full circumference, a primary transfer unit that transfers the toner image formed on the photoconductor to the intermediate transfer member, and a secondary transfer unit that transfers the toner image on the intermediate transfer member to a transfer material. A monocolor image that includes a transfer unit and a fixing unit that fixes the toner image transferred to the transfer material onto the transfer material, and forms a single color image at a first process speed using one type of toner There are a formation mode and a full-color image formation mode for forming a multicolor image at a second process speed slower than the first process speed by using toners of a plurality of colors, and a single color is formed in the same plane of the intermediate transfer member. Form images and multicolor images Image forming apparatus characterized by operating in the second process speed if you. 2. At least one photoconductor, a plurality of developing devices that develop with a plurality of toners of different colors to form a toner image on the photoconductor, and images of two or more pages can be formed in the same plane. An intermediate transfer member having a full circumference, a primary transfer unit that transfers the toner image formed on the photoconductor to the intermediate transfer member, and a secondary transfer unit that transfers the toner image on the intermediate transfer member to a transfer material. A monocolor image that includes a transfer unit and a fixing unit that fixes the toner image transferred to the transfer material onto the transfer material, and forms a single color image at a first process speed using one type of toner And a full-color image forming mode for forming a multi-color image by performing at least secondary transfer and fixing at a second process speed slower than the first process speed using a plurality of color toners. The intermediate transfer member When forming a monochrome image and color image are in the same plane image forming apparatus which is characterized in that the fixing and the secondary transfer by the second process speed. 3. At least one photoconductor, a plurality of developing devices for developing with a plurality of toners of different colors to form a toner image on the photoconductor, and a transfer material having two or more pages in the same plane. A transfer material carrier having an entire perimeter that can be conveyed and transferring a toner image formed on a photoconductor to the transfer material, and fixing for fixing the toner image transferred to the transfer material to the transfer material. A mono-color image forming mode for forming a single-color image at a first process speed using one kind of toner, and a second process slower than the first process speed using a plurality of color toners. An image characterized by having a full-color image forming mode for forming a multi-color image at a speed and operating at a second process speed when a single-color image and a multi-color image are formed on the same surface of a transfer material carrier. Forming equipment. 4. At least one photoconductor, a plurality of developing devices that develop with a plurality of toners of different colors to form a toner image on the photoconductor, and a transfer material having two or more pages in the same plane. A transfer material carrier having an entire perimeter that can be conveyed and transferring a toner image formed on a photoconductor to the transfer material, and fixing for fixing the toner image transferred to the transfer material to the transfer material. A mono-color image forming mode for forming a single color image at a first process speed using one kind of toner, and a second process speed slower than the first process speed using a plurality of color toners It has a full-color image forming mode in which a multi-color image is formed by fixing the image in the same manner, and when a single-color image and a multi-color image are formed on the same surface of the transfer material carrier, the fixing is performed at the second process speed. Image forming apparatus characterized by .