JPH05127487A - Full color copying machine - Google Patents

Abstract

PURPOSE:To obtain a full color copying machine which is not contaminated by toner falling at the time of recovering developing napping. CONSTITUTION:When development by yellow is finished in a 1st developing cycle which starts at time T1, the development by magenta is started at T2. When the development by magenta is finished, the development by cyan is started at T3. The time when a transfer intermediate body is rotated in the case of performing development by yellow, magenta and cyan is T1Y, T1M and T1C. When the 1st developing cycle is finished, the development by yellow in a 2nd developing cycle is started at T4, and the development by magenta and the development by cyan are started at T5 and T6, respectively. The time when the transfer intermediate body is rotated in the case of performing such development is T2Y, T2M and T2C. The time T1M, T2Y, T2M and T2C are all equal to the sum of a specified time t4 that the transfer intermediate body is idly rotated and the specified developing time t3, and on the other hand, the time T1C is shorter than the time T1M, T2Y, T2M and T2C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic full-color copying machine.

[0002]

2. Description of the Related Art In a conventional electrophotographic copying machine, in order to form a document image on a recording medium (final recording medium such as paper), the document is first illuminated by a light source lamp or the like, The reflected light is applied to the uniformly charged photoconductor through a reflecting mirror or the like. The photoconductor is exposed by receiving the reflected light from the document, and an electrostatic latent image having a pattern corresponding to the document image is formed on the surface of the photoconductor.

Then, the electrostatic latent image is developed as a toner image and visualized by the toner in the developing tank, and the toner image is transferred to a transfer intermediate. The toner image transferred to the transfer intermediate is transferred to the recording medium. Thereafter, the toner image on the recording medium is fused, and the copying is completed.

When full-color copying is carried out in such an electrophotographic copying machine, development is carried out in the order of yellow, magenta and cyan. In this developing cycle,
The timings of yellow development, magenta development that starts after the completion of yellow development, and cyan development that starts after the completion of magenta development are set in the same manner. The original image is developed as a toner image on the photoconductor in this order, the developed toner image is transferred to a transfer intermediate, and a combined image in which the yellow, magenta, and cyan toner images are combined is formed on the transfer intermediate. It is formed.

Further, in a full-color copying machine which performs development by the superposition method, yellow, magenta and cyan, and yellow,
There are two development cycles in the order magenta and cyan.
Similarly, the original image is developed as a toner image on the photoconductor in this order, the developed toner image is transferred to the transfer intermediate, and the yellow, magenta, and cyan toner images are combined on the transfer intermediate. An image is formed.

[0006]

In a conventional full-color copying machine which develops by such a superimposing method, there is a phase difference between the developing tanks for color copying, so that especially A3 size or larger size originals are printed. When copying, the first development cycle is performed in order to transfer and superimpose the toner image developed in the second development cycle on the toner image developed in the first development cycle and transferred onto the transfer intermediate. During the period from the end of the cyan development to the start of the yellow development in the second development cycle, it is necessary to idle the transfer intermediate body by one rotation.

The toner that falls off during the development brush recovery by yellow development in the first development cycle is collected at this development brush because the development brush developed by the next magenta development comes out at the same time, and at the development brush recovery time by magenta development. The toner that falls off is collected by the developing brush by the next cyan development. However, the toner that falls when the developing brush is collected by the cyan development in the first developing cycle is not collected in the developing brush by the second developing because the phase of the yellow developing tank is in front, and the cyan toner in the first developing cycle is not collected. The developing ears due to the developing process are also collected at the trailing edge of the image area of the transfer intermediate like the developing ears of other colors. Therefore, the toner that falls during the recovery of the developing ears is transferred to the transfer intermediate during idle rotation. However, there is a problem in that the toner transferred and attached in this manner appears on the copy image and appears as dirt.

Therefore, the present invention provides a full-color copying machine capable of obtaining a copied image which is not contaminated by the toner that falls when the developing brush is collected by the development of cyan in the first developing cycle.

[0009]

A plurality of developing devices each including a photoconductor and a developing device, wherein the developing device develops an image formed on the photoconductor in accordance with an original image with a toner of a plurality of colors in each cycle. A full-color copying machine having a cycle, in which a transfer means for transferring a toner image formed on a photoconductor by a developing means to a transfer body, and an image for forming a toner image transferred on the transfer body by the transfer means on a sheet Control for controlling the timing of development by the developing means based on the forming means, the predetermined development timing in the predetermined development cycle, and the last development timing in the predetermined development cycle set to be shorter than the predetermined development timing. And means.

[0010]

The image formed on the photoconductor in accordance with the original image is
In each of the plurality of developing cycles, the developing means develops the toner with a plurality of colors. The toner image developed and formed on the photoconductor is transferred to the transfer body by the transfer unit. The toner image formed on the transfer body is formed as a copy image on a sheet by the image forming unit. During such copying, the control means is based on a predetermined development timing in a predetermined development cycle and a final development timing in a predetermined development cycle set to be shorter than the predetermined development timing. Control the development of the developing means. As a result, the recovery point of the developing brush in the final development of the predetermined developing cycle advances, and the toner dropped during the recovery of the developing brush is collected in the non-image area of the transfer body. Therefore, since the toner that falls during the recovery of the developing chain by the final development in the predetermined developing cycle is not transferred to the image area of the transfer body, it is possible to obtain a copy image without stains.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a side view showing the construction of an embodiment of a full-color copying machine according to the present invention.

As shown in FIG. 2, the full-color copying machine 10 of this embodiment is provided with an original table 11 made of transparent glass on the upper surface of the machine frame.

An exposure optical system 12 is arranged below the document table 11. The exposure optical system 12 includes a light source lamp 12a for irradiating the original 13 placed on the original placing table 11 with light, and the original 13
A plurality of reflecting mirrors 12b, 12c, 12d, 12e for guiding the reflected light from the photoconductor 14 along the optical path indicated by the alternate long and short dash line and
12f, an imaging lens 12g arranged on the optical path, and a color separation filter 12 having color filters of three primary colors of red, green and blue.
contains h and.

The light source lamp 12a and the reflecting mirrors 12b, 12c and 12
d is configured to be movable in parallel with the document placing table 11 along a bidirectional arrow shown in the drawing by a driving device (not shown).

On the optical axis of the exposure optical system 12, there is arranged a belt-shaped photosensitive member 14 made of an organic photosensitive member (OPC) to which a light image subjected to exposure scanning is irradiated.

Below the photoconductor 14, a paper 15 is stored.
Two paper feed cassettes 16 and 17 are provided. Paper feed rollers 18 and 19 are provided on the upper surfaces of the paper feed cassettes 16 and 17, respectively.

The paper feed rollers 18 and 19 are constructed so as to eject the paper 15 from the paper feed cassettes 16 and 17, respectively, and send it out toward the transfer intermediate 20.

A timing roller 21 is provided on the delivery side of the paper 15 from the paper feed rollers 18 and 19 toward the transfer intermediate 20, and the timing roller 21 rotates in synchronization with the transfer intermediate 20. Is configured.

The transfer intermediate body 20 is constituted so as to be rotationally driven in the clockwise direction (arrow shown in the figure) by the first, second and third rollers 22a, 22b and 22c. It is pressed against a driving roller 23 that is rotationally driven.

A primary transfer charger 24 is provided on the back surface side of the transfer intermediate 20 in the portion where the drive roller 23 is pressed against the transfer intermediate 20.

A secondary transfer roller 26 is provided in contact with the transfer intermediate body 20 on the surface side of the transfer intermediate body 20 in the portion where the third roller 22c is provided.

On the side of the secondary transfer roller 26 where the paper 15 is delivered,
The peeling plate 27, the transport belt 28, and the fixing device 29 are
They are arranged in this order.

The photoconductor 14 irradiated with the reflected light from the exposure optical system 12 is configured to be driven to rotate in the counterclockwise direction (arrow shown in the figure) by the driving roller 23 and the driven roller 30.

In the vicinity of the outer periphery of the driven roller 30, a cleaning device 31 for removing the toner remaining on the photoconductor 14,
Static elimination lamp unit 32 for eliminating static electricity on the photoconductor 14 and the photoconductor 14
A charging charger 33 for charging is disposed in this order along the rotation direction of the photoconductor 14.

The cleaning device 31 is provided with cleaning blades 31a made of, for example, urethane. These cleaning blades 31a are pressed against the photoconductor 14 so as to scrape off, for example, toner remaining on the photoconductor 14. It is configured.

Above the photoconductor 14, a black and white developing tank 41 and color developing tanks 42, 43 and 44 are arranged in a non-contact state with the photoconductor 14. Color developing tanks 42, 43 and
The yellow, magenta, and cyan color developers are contained in 44, respectively.

The full-color copying machine 10 of this embodiment is equipped with a control device 45 for setting and controlling the switching timing of the developing tanks 42, 43 and 44. The control device 45 is connected to the developing tanks 42, 43 and 44 via a cable (not shown).

Next, the operation of the full-color copying machine 10 of this embodiment will be described.

When a copy start switch (not shown) provided in the full-color copying machine 10 is pressed, the copy mode is executed. This copy mode has a copy cycle in which yellow, magenta, and cyan are developed and transferred to the transfer intermediate 20, and when the copy mode is executed, the yellow copy cycle is executed first.

That is, the original 13 placed on the original table 11
On the other hand, light is emitted from the light source lamp 12a to perform exposure scanning. The reflected light from the original 13 is passed through the reflecting mirrors 12b, 12c and 12d and the image forming lens 12g, and the color separation filter 12
Separated by h by color component.

The color separation filter 12 is formed by the above-described exposure scanning.
The light for each color component transmitted through each color filter of h is reflected by the reflecting mirror 12e.
And 12f, the photosensitive member 14 uniformly charged by the charging charger 33 is irradiated, and the photosensitive member 14 is exposed at the P portion.

As a result, a yellow electrostatic latent image corresponding to the image of the original 13 is formed on the photoconductor 14. This electrostatic latent image is developed by a developing magnet roller at a portion facing a developing tank 42 having a yellow developer which is a complementary color of the color separation filter 12h.
The toner is developed and visualized by the developer supplied by 42a to form a toner image. This toner image is transferred to the transfer intermediate 20 by the primary transfer charger 24.

At the end of this yellow copying cycle,
The photoconductor 14 is cleaned by the cleaning device 31 and discharged by the charge eliminating lamp unit 32.

Thereafter, the magenta and cyan toner images are transferred to the transfer intermediate 20 in the same copying cycle as the yellow copying cycle described above.

According to the superimposition method, following the first development cycle in which yellow, magenta, and cyan are developed and transferred to the transfer intermediate 20, respectively, yellow,
A second development cycle is performed in which magenta and cyan are developed and transferred to the transfer intermediate 20.

When the first and second development cycles of yellow, magenta and cyan are executed, the developing tank 42,
The switching timing of 43 and 44 is controlled by the control device 45 as described later.

Therefore, when the yellow, magenta, and cyan copying cycles, that is, the first and second developing cycles, are performed, the toner images for each color component are transferred to the transfer intermediate 20 by the primary transfer charger 24. Transferred to a position and completed by superimposing toner images for each color component 1
One toner image is formed.

On the other hand, the sheets 15 stored in the sheet feeding cassettes 16 and 17 are fed one by one to the timing roller 21 by the sheet feeding rollers 18 and 19, and the timing roller 21 is synchronized with the rotational driving of the transfer intermediate 20. Then, the paper 15 is conveyed between the transfer intermediate 20 and the secondary transfer roller 26.

After the toner image formed on the transfer intermediate body 20 is transferred by the secondary transfer roller 26 to the conveyed paper 15, the sheet 15 is separated from the transfer intermediate body 20 by the peeling plate 27, and is fixed by the conveying belt 28. Introduced to 29.

After the toner image is fixed on the paper 15 by the fixing device 29, the paper 15 is discharged to the outside, and the one-time copying mode is completed.

In this way, yellow on the transfer intermediate,
Since it is necessary to align the magenta and cyan toner images, the peripheral length of the photosensitive member (the length in the direction in which the belt-shaped photosensitive member rotates) is the peripheral length of the transfer intermediate member (the belt-shaped transfer intermediate member rotates). It is configured to be an integral multiple of the length in the direction of.

Next, the yellow, magenta and cyan developing tanks 4 included in the full-color copying machine 10 of this embodiment are used.
The configuration of the control device 45 that sets and controls the switching timing of 2, 43 and 44 will be described.

FIG. 3 is a block diagram showing an embodiment of the control device 45.

As shown in the figure, the control device 45 of this embodiment comprises a CPU (central processing unit) 51, a RAM (random access memory) 52 and a ROM (read only memory) 53.

The CPU 51 includes a RAM 52, a ROM 53, and FIG.
Yellow, magenta and cyan developing tanks 42, 43 and
44 and a copy start switch (not shown in FIG. 2).

The ROM 53 stores predetermined data relating to the switching timing of the developing tanks 42, 43 and 44 when executing the above-mentioned copy mode.

The CPU 51 connects the CPU 51 to a driving device (not shown) for driving the photoconductor 14 and the transfer intermediate 20, and drives the photoconductor 14 and the transfer intermediate 20 at a predetermined timing described later. It can be configured to control.

The photoconductor 14 is an example of the photoconductor of the present invention. The transfer intermediate 20 is an example of the transfer body of the present invention.
The primary transfer charger 24 is an embodiment of the transfer means of the present invention. Secondary transfer roller 26, peeling plate 27, conveyor belt
28 and the fixing device 29 are examples of the image forming means of the present invention. The developing tanks 42, 43 and 44 are an example of the developing means of the present invention. The control device 45 is an embodiment of the control means of the present invention.

Next, the operation of the control device 45 will be described.

FIG. 1 shows a control device 45, in particular a control device.
It is a timing chart for explaining the operation of the CPU 51 included in 45.

Here, in the case where the peripheral length of the belt-shaped photosensitive member 14 of FIG. 2 is configured to be twice the peripheral length of the belt-shaped transfer intermediate 20, the development cycle of yellow, magenta and cyan is 2 times. Control device in copy mode including 45 times
An example of the operation will be described.

In FIG. 1, the horizontal axis indicates the operation timing signal of the transfer intermediate 20 with respect to time (T), the operation timing signal of the photoconductor 14, the yellow developing tank 42, and the magenta developing tank.
The developing timings of the developing tank 43 and the cyan developing tank 44 are shown in order from the top.

In the figure, Δt ₁ is the operation time corresponding to one rotation of the transfer intermediate 20, and Δt ₂ is the operation time of the photoconductor 14.

As shown in the figure, when the copy start switch is pressed at time T = 0, yellow development in the first development cycle starts at a predetermined time T ₁ . The time ΔT _1Y shown in the figure is a predetermined time during which the transfer intermediate 20 rotates when developing the yellow.

Next, when the yellow development is completed, the transfer intermediate 20 is idled for a predetermined time Δt ₄ at a predetermined time T ₂ , and then magenta development is performed for a predetermined time Δt ₃ . The time ΔT _1M during which the transfer intermediate 20 rotates during the magenta development is equal to Δt ₄ + Δt ₃ . here,
The time Δt ₄ can be the time required for the transfer intermediate 20 to rotate by one round.

Next, when the development of magenta is completed, the transfer intermediate 20 is idled for a predetermined time Δt ₄ at a predetermined time T ₃ , and then cyan development is performed for a predetermined time Δt ₃ ′. The time ΔT _1C during which the transfer intermediate 20 rotates during the development of cyan is equal to Δt ₄ + Δt ₃ ′.

However, this time T _1C is set so as to be shorter than the time ΔT _1M during which the transfer intermediate body rotates during the development of magenta. That is, for example, the time Δt ₃ ′ for developing cyan is set to be shorter than the time Δt ₃ for developing magenta.

Thus, when the first development cycle is completed in the order of yellow, magenta, and cyan, a predetermined time T ₄ is reached.
After the transfer intermediate 20 is idly rotated for a predetermined time Δt ₄ , the yellow development in the second development cycle is performed for a predetermined time Δt ₃ . The time ΔT _2Y during which the transfer intermediate 20 rotates during the development of the yellow _color is equal to Δt ₄ + Δt ₃ .

After the yellow development is completed, the transfer intermediate 20 is idled for a predetermined time Δt ₄ at a predetermined time T ₅ , and then magenta development is performed for a predetermined time Δt ₃ . The time ΔT _2M during which the transfer intermediate 20 rotates during the magenta development is equal to Δt ₄ + Δt ₃ .

Next, when the magenta development is completed, the transfer intermediate 20 is idled for a predetermined time Δt ₄ at a predetermined time T ₆ , and then cyan development is performed for a predetermined time Δt ₃ . The time ΔT _2C during which the transfer intermediate 20 rotates during the development of cyan is equal to Δt ₄ + Δt ₃ .

As described above, the time ΔT _1M during which the transfer intermediate 20 rotates when developing magenta in the first developing cycle and the time when yellow, magenta and cyan developing in the second developing cycle are performed. Transfer intermediate 20
The rotation times ΔT _2Y , ΔT _2M, and ΔT _2C are all equal, while the rotation time T _1C of the transfer intermediate 20 during the cyan development in the first development cycle is the time ΔT. It is set to be shorter than _1M , ΔT _2Y , ΔT _2M and ΔT _2C .

However, the time ΔT _1Y during which the transfer intermediate 20 rotates when the yellow development is performed in the first development cycle.
Does not include the time during which the transfer intermediate 20 idles, and thus is generally the shortest.

Therefore, the collecting point of the cyan developing chain in the first developing cycle advances, and the toner falling during the collecting of the cyan developing chain is collected in the non-image area of the transfer intermediate.

Therefore, the toner that falls when the developing brush is collected is
Since it does not appear in the idling image area between the development of cyan in the first development cycle and the development of yellow in the second development cycle, a copy image without stain can be obtained.

As a preferred example, the time ΔT _1M during which the transfer intermediate rotates during the development of magenta in the first development cycle and the development of yellow, magenta and cyan in the second development cycle. The transfer intermediate rotation time ΔT _2Y , ΔT _2M, and ΔT _2C are all 6.14 seconds, and the transfer intermediate rotation time T _1C during cyan development in the first development cycle is It may be 6.00 seconds. In this case, compared with the case where the time T _1C is set to 6.14 seconds, the collecting point of the cyan developing chain in the first developing cycle is advanced by 22 mm, and the toner falling at the time of collecting the cyan developing chain is the non-transfer intermediate. Image area (30
mm).

The operation of the control device 45 for setting and controlling the switching timing of the yellow, magenta and cyan developing tanks 42, 43 and 44 shown in FIG. 1 is preprogrammed, and the program thereof is the ROM 53 of FIG. Remembered in. The program stored in the ROM 53 can be read and executed by the CPU 51.

In the above-described embodiment, an example in which development is performed in the order of yellow, magenta, and cyan has been shown, but the order of development is not necessarily limited to this order. The developer contained in each of the developing tanks 42, 43, and 44 shown in FIG. 2 may be changed so that the desired developing sequence is obtained.

[0069]

As described above, according to the present invention, the photosensitive member and the developing means are provided, and the developing means forms the image formed on the photosensitive body in accordance with the original image with the toner of plural colors in each cycle. A full-color copying machine having a plurality of development cycles for developing by means of a transfer means for transferring a toner image formed on a photoreceptor by a developing means to a transfer body, and a toner image transferred to the transfer body by the transfer means. Development by the developing means based on the image forming means formed on the sheet, the predetermined developing timing in the predetermined developing cycle, and the last developing timing in the predetermined developing cycle set to be shorter than the predetermined developing timing. And a control means for controlling the timing of. Therefore, since the toner that falls during the recovery of the developing chain by the final development in the predetermined developing cycle is not transferred to the image area of the transfer body, it is possible to obtain a copy image without stains.

[Brief description of drawings]

FIG. 1 is a timing chart for explaining an operation of a CPU included in a control device.

FIG. 2 is a side view showing the configuration of an embodiment of a full-color copying machine according to the present invention.

FIG. 3 is a block configuration diagram showing an example of a configuration of a control device.

[Explanation of symbols] 10 Full-color copying machine 14 Photoconductor 20 Transfer intermediate 24 Primary transfer charger 26 Secondary transfer roller 27 Peeling plate 28 Conveyor belt 29 Fixing device 45 Control device 51 CPU

Claims (1)

[Claims] 1. A plurality of developing cycles, each of which includes a photoconductor and a developing means, wherein the developing means develops an image formed on the photoconductor according to an original image with a toner of a plurality of colors in each cycle. A full-color copying machine having the transfer means for transferring the toner image formed on the photoreceptor by the developing means to a transfer body, and the toner image transferred on the transfer body by the transfer means on a sheet. Of the developing means based on the image forming means, the predetermined developing timing in the predetermined developing cycle, and the last developing timing in the predetermined developing cycle set to be shorter than the predetermined developing timing. A full-color copying machine comprising: a control unit for controlling timing.