JP2003255683A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus provided with a toner replenishing device carrying out toner replenishing control at high precision even when a plurality of carrying screws rotated by a single motor through an operation changeover means are rotated. <P>SOLUTION: The color image forming apparatus is characterized in that the rotation of a replenishing screw is stopped by stopping the motor first and then carrying out toner replenishing control of the toner replenishing device by turning off an operation changeover means. <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 an electrophotographic system such as a copying machine, a printer, and a FAX, and more particularly to a color image forming apparatus provided with a toner replenishing device for highly accurately controlling toner replenishment.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic color image forming apparatus such as a copying machine, a printer or a fax machine is provided with a plurality of developing means (hereinafter referred to as developing devices) each containing a developer of a different color, and a latent image for each color is provided. The image is developed into a toner image, and the toner image is superposed on the recording material to form a color image.
Since the developing device consumes toner by development, a toner replenishing device is provided for each developing device to replenish the toner consumed by the transport screw.

[0003]

In the toner replenishing device for replenishing toner to the developing device of the color image forming apparatus as described above, when a plurality of toner replenishing devices are made to replenish toner by a single motor, a plurality of toners are replenished. An electromagnetic clutch (operation switching means) is provided for each of the transport screws (objects to be rotated) of the replenishing device, the motor is turned on (operating state),
The electromagnetic clutch is turned on (engaged state), the transport screw is rotated, and toner is replenished.

However, when the motor is used to rotate the conveying screw having an operation switching means such as an electromagnetic clutch, the starting time of the clutch at the time of starting and stopping the toner replenishment at the time of replenishing the toner, the variation time thereof and the stop time thereof, and the time thereof. Since the variation time is larger than the motor start time and its variation time and stop time and its variation time, there arises a problem that the toner replenishment variation time becomes long when setting the toner amount when the clutch is on.
In particular, when a plurality of transport screws having an operation switching means such as an electromagnetic clutch are rotated by a single motor, there arises a problem that variation time of toner replenishment becomes long. In particular, when a small amount of toner is replenished, the fluctuation of the replenishment amount due to the error increases.

The present invention solves the above problems and forms a color image with a toner replenishing device for accurately controlling the toner replenishment even when a plurality of conveying screws rotated by the operation switching means are rotated by a single motor. A first object is to provide a device.

Further, when a plurality of transport screws having operation switching means such as an electromagnetic clutch are rotated by a single motor, the toner in at least one toner replenishing device is not replenished, and the toner replenishing device is not operated. When the toner in the developing device is reduced and the ratio of the carrier in the developer in the developing device becomes large, the development is performed only by the carrier and the photosensitive drum (image forming body) is damaged. The problem occurs.

The present invention solves the above-mentioned problems, and in the case where a single motor rotates a plurality of conveying screws rotated through an operation switching means such as an electromagnetic clutch, the toner in at least one toner replenishing device is Is not replenished, and even if the toner in the toner replenishing device is low,
A second object of the present invention is to provide a color image forming apparatus in which toner is replenished accurately without damaging an image forming body by setting an appropriate ratio of carriers in a developer in a developing device. .

[0008]

A first object of the present invention is to develop a latent image, a developing means for developing a latent image, a toner storage container for storing toner, and a toner supply for supplying the toner from the toner storage container to the developing means. In a color image forming apparatus for controlling toner replenishment by rotating a replenishing screw provided in a plurality of sets of toner replenishing devices through operation switching means by a single motor, rotation stop of the replenishing screw is performed. , Stop the motor first,
After that, the operation switching means is turned off to control the toner replenishment of the toner replenishing device (first invention), the developing means for developing the latent image, and the toner are stored. A plurality of toner replenishing devices for supplying toner from the toner reserving container to the developing means, and a replenishing screw provided for a plurality of toner replenishing devices through operation switching means by a single motor. In a color image forming apparatus that controls the toner replenishment by rotating the toner replenishment control device, when the toner replenishment is started, the operation switching means of the replenishment screw is turned on first, and then the motor is rotated so that the toner of the toner replenishment device is rotated. This is achieved by a color image forming apparatus (second invention) characterized by performing replenishment control.

The second object is to develop the latent image on the image forming body, a toner container for containing toner, and a toner replenishing device for supplying the toner from the toner container to the developing device. In a color image forming apparatus for controlling toner replenishment by rotating a plurality of sets of toner replenishing devices provided in a plurality of sets of toner replenishing devices through operation switching means by a single motor, as a motor for rotating a plurality of replenishing screws. A stepping motor is used, and when the toner in the toner container reaches a predetermined level, the measurement of the number of rotation pulses of the stepping motor is started, and the total number of rotation pulses of the stepping motor exceeds a certain value. The color image forming apparatus is characterized by forcibly stopping the color image forming apparatus when Is achieved by the invention).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. Note that the description in this section does not limit the technical scope of the claims or the meaning of terms. Further, the following affirmative description in the embodiments of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

An image forming process and each mechanism of an embodiment of a color image forming apparatus having a toner replenishing device according to the present invention will be described with reference to FIGS. 1 to 4.
1 is a cross-sectional configuration diagram of an embodiment of a color image forming apparatus including a toner replenishing device according to the present invention.
3 is a diagram showing an outline of toner supply in the color image forming apparatus of FIG. 1, FIG. 3 is a schematic side sectional view of the toner supply device in FIG. 2, and FIG. 4 is a cross section of the toner supply device in FIG. FIG. 5 is a timing chart showing the rotation control of the motor and the supply screw, and FIG. 6 is a timing chart showing the control method in the case of rotating a plurality of supply screws by a single motor. .

As shown in FIG. 1, a color image forming apparatus using a fixing device according to the present invention is an image forming unit for forming color toner images of black, cyan, magenta and yellow along a moving direction of a transfer material. Are arranged, and the color toner images formed on the image forming bodies of the respective image forming units are transferred onto the transfer material (recording paper) conveyed by the transfer material conveying means so as to be superposed.

In the figure, four sets for forming an image for each color of yellow (Y), magenta (M), cyan (C) and black (K) are provided on the peripheral portion of a transfer belt 14A which is a transfer material transfer means. Process unit 100 of Y, M, C with respect to the rotation direction of the conveyor belt 14A indicated by the arrow in the figure.
And K in this order.

The four process units 100 have a common structure, and each of them has a photosensitive drum 10 as an image forming body and a scorotron charger 11 as a charging means.
An exposure optical system 12 as image writing means, a developing device 13 as developing means, and an image forming body cleaning device 19 as image forming body cleaning means.

The photosensitive drum 10, which is an image forming body, has a transparent conductive layer and an organic photosensitive layer on the outer periphery of a cylindrical substrate formed of a transparent member such as glass or a transparent acrylic resin. (OPC) photoconductor layer is formed.

The photosensitive drum 10 is rotated in the clockwise direction indicated by the arrow with the light-transmitting conductive layer being grounded by the power from a drive source (not shown) or by following the conveyor belt 14A.

Scorotron charger 11 as charging means
Are attached in close proximity to the photoconductor drum 10 in a direction orthogonal to the moving direction of the photoconductor drum 10 (direction perpendicular to the paper surface in the figure). Scorotron charger 11
Is equipped with a control grid held at a predetermined potential with respect to the organic photoconductor layer of the photoconductor drum 10 and a discharge wire as a corona discharge electrode. (Negative charging) to give a uniform potential to the photoconductor drum 10.

The exposure optical system 12 as an image writing means,
A linear exposure element in which a plurality of LEDs (light emitting diodes) as light emitting elements for image exposure light are arranged in an array in parallel with the axis of the photoconductor drum 10 for each color and a SELFOC lens as an equal magnification imaging element (R) is configured as an exposure unit attached to a holder, and the exposure optical system 12 for each color
Is attached to a cylindrical holder 20 as an exposure optical system holding member, and is integrally housed inside the base of the photosensitive drum 10. The exposure optical system 12 performs image processing based on the image data of each color sent from a separate computer (not shown) and stored in the memory, and then exposes the uniformly charged photosensitive drum 10 from the back side. (Image writing) is performed to form a latent image on the photoconductor drum 10.

The developing device 13 as a developing means has two components of each color of yellow (Y), magenta (M), cyan (C) or black (K) charged to the same polarity as the photosensitive drum 10. Developer (may be a one-component developer)
Respectively, and has a thickness of 0.5 to 1 mm and an outer diameter of 1
Developing roller 13 which is a developer carrier made of non-magnetic stainless steel or aluminum having a cylindrical shape of 5 to 25 mm
1 is provided. The developing roller 131 is kept in non-contact with the photoconductor drum 10 with a predetermined gap, for example, 100 to 1000 μm, by an abutting roller (not shown), and is rotated in the forward direction of the rotation direction of the photoconductor drum 10. At the time of development, a DC bias voltage having the same polarity as the toner (negative polarity in this embodiment) or a developing bias voltage for superimposing an AC voltage on a DC voltage is applied to the developing roller 131, whereby Non-contact reversal development is performed on the exposed portion on 10.

Conveyor belt 14A as a transfer material conveying means
Has a volume resistivity of 10 ⁸ to 10 ¹⁵ Ω · cm and a surface resistivity of 1
0 ^8-10 was ¹⁵ Omega / □ endless belt, for example modified polyimide, thermal curing polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, thickness 0 the conductive material is dispersed in engineering plastics nylon alloy or the like. A seamless belt having a two-layer structure, in which a semi-conductive film substrate having a thickness of 1 to 0.5 mm is coated with fluorine to a thickness of 5 to 50 μm as a toner filming preventing layer, preferably. In addition to this, a semi-conductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber, urethane rubber or the like can be used as the base body of the transport belt 14A. The transport belt 14A is circumscribed and stretched around the drive roller 14d, the driven roller 14e, the backup roller 14j, and the tension roller 14k.

The image forming process (image forming process) will be described below. When the image recording is started, the drive roller 14d is rotated by the start of the drive motor of the transfer material conveying means (not shown), and the conveying belt 14A is rotated in the direction shown by the arrow in the figure.

The yellow (Y) process unit 1
In 00, the Y photoconductor drum 10 is rotated in the direction shown by the arrow in the figure by the start of the photoconductor drive motor (not shown), and Y
Y photoconductor drum 1 by the scorotron charger 11
A potential is applied to 0. After a potential is applied to the Y photoconductor drum 10, the Y exposure optical system 12 performs exposure (image writing) with a first color signal, that is, an electric signal corresponding to Y image data, and the Y photoconductor drum 10 is exposed. An electrostatic latent image corresponding to a yellow (Y) image is formed on the body drum 10.
The latent image is reversely developed by the Y developing device 13 in a contact or non-contact state, and a yellow (Y) toner image is formed on the Y photoconductor drum 10.

On the other hand, in parallel with the formation of the Y toner image on the Y photoconductor drum 10, the recording paper P is sent out from the paper feed cassette 15 as a transfer material accommodating means by the sending roller, and the feeding roller is operated. After that, it is conveyed to the timing roller 16 as a transfer material feeding means. Furthermore, recording paper P
Is sent from the timing roller 16 in synchronism with the Y toner image formed on the Y photoconductor drum 10, and is attracted to the transport belt 14A by the charging of the paper charger 150 as the transfer material charging means. And then the conveyor belt 14A
Is carried to the Y transfer area.

In the Y transfer area, the Y toner on the Y photoconductor drum 10 is transferred by the transfer roller 14C as the Y transfer means to which the voltage having the opposite polarity (positive polarity in this embodiment) to the toner is applied. The image is transferred onto the recording paper P.

Simultaneously with or slightly after the operation of the Y process unit 100, in the magenta (M) process unit 100, the M photoconductor drum 10 is rotated in the direction indicated by the arrow in the figure, and the M scorotron charger is charged. A potential is applied by the charging action of 11 and the M exposure optical system 12 exposes (image-writes) the second color signal, that is, an electric signal corresponding to image data of magenta (M) on the M photoconductor drum 10. And an electrostatic latent image is formed on the surface of the electrostatic latent image.
A magenta (M) toner image is formed on the photosensitive drum 10 of FIG.

In parallel with the formation of the M toner image on the M photoconductor drum 10, the recording paper P carrying the yellow (Y) toner image is conveyed to the M transfer area by the conveying belt 14A. In the M transfer area, the M transfer roller 14C transfers the M toner image formed on the M photoconductor drum 10 onto the recording paper P carrying the M toner image. A color toner image in which Y and M are superposed is formed on.

By the same process, a toner image of cyan (C) and a toner image of black (K) are sequentially transferred in a superposed manner, and the color of the superposed Y, M, C and K is recorded on the recording paper P. A toner image is formed.

The recording paper P on which the superimposed color toner images have been transferred is a paper separation static eliminator 14 as a transfer material separating means.
It is separated from the conveyor belt 14A by h and is conveyed to the fixing device 17 described later in detail.

After the superimposed color toner images on the recording paper P are fixed in the fixing device 17, the recording paper P is ejected to the tray on the upper part of the device through the paper ejection roller 18.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is cleaned by an image forming body cleaning device 19 as an image forming body cleaning means, and the next image forming cycle is started.

In the above, Y,
The color image forming apparatus of the method (multi-developing intermediate transfer method) in which the toner images of M, C, and K are superimposed and formed, and then the superimposed toner images are collectively transferred onto the transfer material has been described. The present invention is not limited to this, and the transfer belt used as the transfer material transfer unit is used as an intermediate transfer member, the toner image is transferred onto the intermediate transfer member, and then the toner image is transferred onto the transfer material. Method (intermediate transfer method) color image forming apparatus, and yellow (Y), magenta (M), cyan (C), and black (K) toner images are sequentially formed on the same photoreceptor, and the toner images are formed. After transferring onto the intermediate transfer body (or forming yellow (Y), magenta (M), cyan (C) and black (K) toner images on a plurality of photoreceptors respectively, and transferring these toner images Transfer the toner image onto the body one after another and After combined), and is applied to a color image forming apparatus such as a method of transferring a toner image superimposed collectively onto a transfer material (multiple transfer intermediate transfer system).

Further, as shown in FIG. 2, Y, M, C and K
Each process unit 100 of FIG.
Toner replenishing devices TH each having a replenishment screw HS therein are provided, which will be described in detail with reference to FIG. Toner is replenished to 13. The toner of each color is supplied from the toner bottle TB which is a toner storage container of each color to the toner replenishing device TH.
Is replenished.

The replenished toner is mixed with the developer in the developing device 13 by the stirring / conveying screws 145 and 146 and stirred, and then supplied to the developing roller 131 by the supply roller 132 and exposed by the developing roller 131. The latent image on the body drum 10 is developed.

From the toner bottle TB to the toner replenishing device TH
To replenish toner to the toner, for example, a piezo element is used, and as described later in detail, based on level detection of a toner level detection sensor TDa that detects the surface level of toner in the toner replenishment device TH, a drive source (not shown) is used. It is replenished from the rotated toner bottle TB. When the toner in the toner replenishing device TH falls below the level of the toner level detecting sensor TDa (a predetermined level La described in detail later) by the level detection of the toner level detecting sensor TDa, toner is replenished from the toner bottle TB. Level Lb
Therefore, the toner in the normal toner supply device TH is kept between the level Lb and the level La.

The supply screw HS is connected to an electromagnetic clutch CH as an operation switching means connected to the motor M, receives the rotation of the motor M, and is rotated through the electromagnetic clutch CH which is turned on-off.

In the present invention, a plurality of toner replenishing devices TH are driven by a single motor M through the electromagnetic clutch CH.
The supply screw HS of is controlled to rotate,
The Y, M, C, and K replenishment screws HS may be rotated by a single motor, but in order to simplify the control system complexity, in the present embodiment, as shown in the figure,
Y, M, and C, K are set as one set, and Y, M,
Further, the replenishment screws HS provided in the C and K toner replenishing devices TH are rotated by the single motor M through the respective electromagnetic clutches CH to perform toner replenishment control.

According to FIG. 3 or FIG. 4, the toner replenishment from the toner replenishing device TH to the developing device 13 is performed by the printing rate of the image to be formed (dots such as a character image or a photographic image occupying the entire screen on which dots are formed). Based on the total ratio) or the detection value of the toner concentration detection sensor TDb using the L detection sensor, for example, it is performed for each print (one sheet) as needed.
Toner supply from the toner supply device TH to the developing device 13 is
Toner replenishment is performed mainly by using the printing rate. At this time, the electromagnetic clutch CH shown in FIG. 3 is turned on (operating state) so that the rotation shaft Jt of the supply screw HS and the gear Ga directly connected to the motor M that is driven and rotated and the drive system Gk.
The motor M is driven to rotate the replenishment screw HS to replenish the toner.

In the following, as the motor M, a stepping motor which is pulse-controlled and has little time variation at the time of starting and stopping is preferably used.
As a result, the influence of the variation time of the rotation of the motor M is suppressed.

FIG. 5 is a timing chart when only one set of toner replenishing device is operated by a single motor to replenish toner, and FIG. 6 is a timing chart of rotation control of the motor and the replenishing screw. 6 is a timing chart showing a control unit in the case of rotating two replenishment screws by a single motor when two sets of toner replenishment devices are simultaneously operated to replenish toner to each. As described at the beginning, the starting time of the electromagnetic clutch CH at the time of starting and stopping the toner replenishment at the time of toner replenishment and its variation time and the stop time and its variation time are the starting time of the motor M and its variation time. Is longer than the stop time and its variation time, and the electromagnetic clutch CH is on (combined state), off.
When the toner is replenished during this period due to the (non-coupling state), the toner replenishment time varies greatly and the toner replenishment amount varies. Therefore, as shown in FIG. 5, the rotation of the replenishment screw HS is stopped by the motor. The rotation of M is first stopped and turned off (inactive state), and at the same time as or immediately after the motor is stopped, the electromagnetic clutch CH is turned off (unconnected state) to control the toner replenishment device TH when toner replenishment is stopped. To This eliminates the influence of variations in the stop time of the electromagnetic clutch CH.

At the start of toner replenishment, the electromagnetic clutch CH connected to the replenishment screw HS is first turned on (combined state), and the time T1 for connecting the electromagnetic clutch CHa is increased.
After the lapse of time, the motor M is turned on (operating state) to rotate, and the control at the time of starting the toner replenishment of the toner replenishing device TH is performed. As a result, the influence of the variation time of the activation time of the electromagnetic clutch CH is eliminated, and the toner replenishment amount can be accurately supplied.

Further, in particular, when two sets of the conveying screws HS are simultaneously rotated by the electromagnetic clutch CH which is the operation switching means connected to the single motor M (hereinafter, one of the replenishing screws HSa and the replenishing screw HSa are rotated. On
The electromagnetic clutch for turning on / off is called CHa, the other replenishing screw is called HSb, and the electromagnetic clutch for turning on / off the rotation of the replenishing screw HSb is called CHb). For example, for Y toner replenishment described in FIG. The replenishment screw used has a high printing rate and has a long toner replenishment time (long rotation time) as a replenishment screw HSa, and the replenishment screw used for M toner replenishment has a low printing rate and a short replenishment time. The supply screw HSb (which has a short rotation time) will be described below.

As shown in FIG. 6, when the single motor M rotates the replenishment screws HSa, HSb through the electromagnetic clutches CHa, CHb, the electromagnetic clutch connected to the replenishment screw HSb having a short rotation time at the start of toner replenishment. CHb and supply screw HS with long rotation time
The electromagnetic clutch CHa connected to a is turned on at the same time.
In the (engaged state), the supply screw HS is rotated by turning the motor M on (operating state) after a lapse of T1 when the connecting operation of the electromagnetic clutches CHa and CHb is stabilized.
b and the rotation of the supply screw HSa are started at the same time, the rotation of the motor M is temporarily stopped (off (inactive state)) according to the operation time of the supply screw HSb having a short supply time, and then the electromagnetic Turn off the clutch CHb
(Non-bonded state). The supply screw HSa having a long rotation time stops along with the stop of the motor M when the supply screw HSb having a short rotation time is stopped (point P1). Also,
The supply screw HSa having a long rotation time keeps the electromagnetic clutch CHa o while the motor M is stopped (between points P2 and P3) to stop the supply screw HSb having a short rotation time.
It is maintained and controlled at n (coupled state). After that, the motor M is turned on again after the electromagnetic clutch CHb is completely disconnected.
After the supply screw HSa is rotated so as to rotate as n (operating state), the supply screw HSa is rotated.
When the scheduled replenishment time is reached in addition to the replenishment time previously interrupted, the rotation of the motor M is stopped first (off).
(Inoperative state)), and then the electromagnetic clutch CHa
Is turned off (non-bonding state) to control the rotation of the supply screw HSa. Electromagnetic clutch CHa
By continuously turning on, the stop time in the middle of the motor M can be shortened.

In the control described above, the temporary stop time Tc of the motor M during one print (between points P2 and P3)
Is controlled to be longer than the total time of the stop time Tb1 of the electromagnetic clutch CHb and its variation time Δtb1.

When the rotation times of a plurality of supply screws are different, the temporary stop time of the motor during one print is the sum of the start time of the electromagnetic clutch and its variation time or the stop time of the electromagnetic clutch. It is controlled so that it becomes larger than the total variation time.

As described above, even when toner is replenished by a plurality of replenishment screws having different rotation times, the toner replenishment amount by each replenishment screw is accurately supplied.

As described above, when rotation control is performed on a plurality of carrier screws through the operation switching means such as an electromagnetic clutch with a single motor, even when only one carrier screw is rotated, the two carrier screws are simultaneously rotated. Even when two toners are replenished by performing the toner replenishment, the toner replenishment according to the present invention eliminates the influence of the factor that affects the variation of the replenishment amount, and it is possible to provide a color image forming apparatus that can replenish the toner accurately.

As described above, in FIG. 2 or FIG. 3, the toner replenishment from the toner bottle TB to the toner replenishing device TH is performed by using, for example, a piezo element, and the toner surface level of the toner in the toner replenishing device TH is detected. Based on the level detection of the level detection sensor TDa, the toner is replenished from the toner bottle TB rotated by a drive source (not shown).
When the toner in the toner replenishing device TH of any of Y, M, C, and K described in FIG. 1 reaches a predetermined level La shown in the drawing, the toner bottle TB of that color is rotated to supply a predetermined amount of toner. The toner is replenished in the toner replenishing device TH, and the toner is replenished by repeating this for a predetermined number of times. A single motor M is used to change Y, M, C and K through a plurality of operation switching means, for example, an electromagnetic clutch CH. When the supply screw HS of the toner supply device TH is rotated (see FIG.
In the case of rotating the replenishment screws HS of the Y, M, C, and K toner replenishing devices TH through the electromagnetic clutch CH by a single motor M), at least Y, M, C, and K. If the toner in the toner replenishing device TH of any one of the toner replenishing devices TH is exhausted and the toner is not replenished, the developing device 1
The toner in 3 is reduced, the ratio of the carrier in the developer in the developing device 13 becomes large, and the development is performed only by the carrier, and the photosensitive drum 10 is damaged.

In order to solve this, a stepping motor capable of pulse control and suppressing the influence of rotation variation time is used as the motor M for rotating the replenishment screws HS of the toner replenishing devices TH for Y, M, C and K, respectively. The toner in the toner replenishing device TH of at least one of the Y, M, C, and K toner replenishing devices TH is the toner level after repeating the predetermined number of times. At the stage when the level has dropped to a predetermined level La which is the same level as the detection sensor TDa, a warning display for replacing the toner bottle TB and a warning display indicating that toner replenishment is required are displayed on an operation unit (not shown) and at the time of toner replenishment. The measurement of the number of rotation pulses of the stepping motor M is started, and the total number of rotation pulses of the stepping motor M becomes equal to one. Value, for example, when it exceeds 10,000 pulses, the toner in the toner supply device is judged that empty, controls to forcibly stop the color image forming apparatus. At this time, control is performed so that the number of rotation pulses of the stepping motor M is counted only when the electromagnetic clutch CH of the supply screw HS is on (in the connected state).

Since the toner replenishment amount after the warning is displayed is highly accurately measured by such control, the operation is stopped immediately before the image forming body is damaged.
Also, there is no need to stop at an early point and cause mechanical disadvantages.

As described above, when toner is replenished by controlling the rotation of a plurality of conveying screws through the operation switching means such as an electromagnetic clutch with a single motor, the toner in at least one toner replenishing device is replenished. Even if the amount of toner in the toner replenishing device decreases, the ratio of the carrier in the developer in the developing device is set to an appropriate ratio, and the toner can be replenished accurately without damaging the image forming body. The color image forming apparatus can be provided.

[0051]

According to the first to seventh aspects of the present invention, when a single motor is used to control the rotation of a plurality of conveying screws through an operation switching means such as an electromagnetic clutch, even when only one conveying screw is rotated, Even when two transport screws are simultaneously rotated to replenish two toners, the toner replenishment of the present invention eliminates the influence of the factor that affects the variation of the replenishment amount, and the toner replenishment is performed accurately. Can be provided.

According to the eighth or ninth aspect of the present invention, at least one toner replenishing device is used when toner is replenished by controlling rotation of a plurality of conveying screws through operation switching means such as an electromagnetic clutch with a single motor. Even if the toner in the toner replenishing device is not replenished and the toner in the toner replenishing device is reduced, the ratio of the carrier in the developer in the developing device should be set to an appropriate ratio before the damage to the image forming body. It is possible to provide a color image forming apparatus in which toner is replenished with high accuracy without damaging the image forming body by stopping the image forming apparatus.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an embodiment of a color image forming apparatus including a toner replenishing device according to the present invention.

FIG. 2 is a diagram showing an outline of toner supply in the color image forming apparatus of FIG.

FIG. 3 is a schematic side sectional view of the toner replenishing device in FIG.

FIG. 4 is a sectional view of the toner replenishing device in FIG.

FIG. 5 is a timing chart showing rotation control of a motor and a supply screw.

FIG. 6 is a timing chart showing a control method when a plurality of supply screws are rotated by a single motor.

[Explanation of symbols]

10 Photosensitive drum 11 Scorotron charger 12 Exposure optical system 13 Developer 14A conveyor belt 14C transfer roller 17 Fixing device 100 process units 131 developing roller 132 supply roller 145,146 Mixing / transport screw CH, CHa, CHb Electromagnetic clutch HS, HSa, HSb Supply screw La predetermined level M motor (stepping motor) Ta1, Ta2 start-up time Δta1, Δta2, Δtb1 Variation time Tb1 stop time Tc Temporary stop time TB toner bottle TDa toner level detection sensor TDb toner concentration detection sensor TH toner supply device

Claims (9)

[Claims] 1. A single motor having a plurality of sets of developing means for developing a latent image, a toner storage container for storing toner, and a toner replenishing device for supplying toner from the toner storage container to the developing means. In the color image forming apparatus for controlling the toner replenishment by rotating the replenishing screws provided in the plurality of sets of toner replenishing devices through the operation switching means, the rotation of the replenishing screw is stopped first, and then the rotation of the motor is stopped. A color image forming apparatus, wherein the operation switching means is turned off to control the toner replenishment of the toner replenishing device. 2. A single motor provided with a plurality of sets of developing means for developing a latent image, a toner storage container for storing toner, and a toner replenishing device for supplying toner from the toner storage container to the developing means. Thus, in a color image forming apparatus for controlling toner replenishment by rotating replenishment screws provided in a plurality of sets of toner replenishing devices through the respective operation reshuffling means, when the toner replenishment is started, the replenishment screw operation switching means is turned on first. The color image forming apparatus is characterized in that the toner replenishment control of the toner replenishing device is performed by subsequently rotating the motor. 3. The replenishment screw having a long rotation time is temporarily stopped when the replenishment screw having a short rotation time is stopped when the rotation times of the plurality of screws are different during one printing. Color image forming apparatus. 4. When the rotation times of a plurality of supply screws are different during one printing, the supply switching screw is turned on for a supply screw having a long rotation time even when the motor is stopped to stop the supply screw having a short rotation time. The color image forming apparatus according to claim 3, wherein: 5. When the rotation times of the plurality of supply screws are different, the temporary stop time of the motor during one print is the total time of the start time of the electromagnetic clutch and its variation time or the stop of the electromagnetic clutch. The color image forming apparatus according to claim 3, wherein the color image forming apparatus is longer than a total time of the time and its variation time. 6. The color image forming apparatus according to claim 1, wherein the motor is a stepping motor. 7. The color image forming apparatus according to claim 1, wherein the operation switching unit uses an electromagnetic clutch. 8. A plurality of sets of developing means for developing a latent image on an image forming body, a toner storage container for storing toner, and a toner replenishing device for supplying toner from the toner storage container to the developing means. , A stepping motor is used as a motor for rotating a plurality of replenishing screws in a color image forming apparatus in which toner replenishing control is performed by rotating a replenishing screw provided in a plurality of sets of toner replenishing devices through respective operation switching means by a single motor. When the toner in the toner storage container reaches a predetermined level, the measurement of the rotation pulse number of the stepping motor is started, and when the total number of rotation pulses of the stepping motor exceeds a certain value, it is forced. A color image forming apparatus characterized in that the color image forming apparatus is stopped temporarily. 9. The operation switching means of the supply screw is o
9. The color image forming apparatus according to claim 8, wherein the rotation pulse number of the stepping motor is counted only when the stepping motor is turned on.