JPH1144990A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of performing the image formation free from image density change or density unevenness by stabilizing the feeding quantity of a developer to a developing device even right after developer replenishment. SOLUTION: This device is constituted by providing an agitating member 11 in the lower part in a toner hopper 10, disposing a toner transporting path 13 connected with the lower part of the toner hopper 10 below the toner hopper 10, and arranging a screw 16 in the toner transporting path 13. The agitation member 11 is, by one end of its rotary shaft 11a connected with a driving motor 19 through gear wheel 20, and the one end of the rotary shaft of the screw 16 is connected with the gear wheel 20 through a clutch 21 and the gear wheel 22. Then, during the specific time right after performing the toner replenishment to the toner hopper 10, the driving motor 19 is operated in a state that the clutch 21 is disconnected so that only the agitation member 11 is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type image forming apparatus such as a copying machine, a printer or a facsimile having a developer supply device for supplying a developer to a developing device for visualizing a latent image. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer or a facsimile, a developer capable of appropriately replenishing toner which is a developer used when developing an electrostatic latent image formed on an image carrier. An image forming apparatus provided with a supply device is known. A typical example is a color electrophotographic copying machine.

FIG. 6 shows an example of a color electrophotographic copying machine. In this copying machine, toner is supplied to each developing unit from a toner supply device fixed to the main body of the developing device having a plurality of developing units.

As shown in FIG. 6, a photosensitive drum 1 as a latent image carrier for carrying an electrostatic latent image is arranged in an image forming apparatus as a color electrophotographic copying machine.
It is supported rotatably in the clockwise direction of the arrow in FIG. Around the photosensitive drum 1, a corona charger 2 for charging the surface of the photosensitive drum 1, a charged photosensitive drum 1
An exposure optical device 3 for exposing the surface of the photosensitive drum 1 to form a latent image on the photosensitive drum 1, a developing device 4 for developing and visualizing the latent image formed on the photosensitive drum 1, a visualized image And a cleaning device 6 for removing waste toner after the transfer.

A document reading system 7 is arranged above devices such as the photosensitive drum 1 and the exposure optical device 3. The document reading system 7 has a document scanning section 7a and a photoelectric element 7b having a color separation filter. The optical device 3 places a color separation electrostatic latent image on the photosensitive drum 1 according to a signal from the photoelectric element 7b. It can be formed.

A developing device 4 for developing a latent image on the photosensitive drum 1 includes, for example, a yellow developing unit 4Y using yellow toner, a magenta developing unit 4M using magenta toner, and a cyan developing unit 4 using cyan toner.
C, black developing unit 4B using black toner
And K development units. Then, a predetermined developing unit is brought into contact with the photosensitive drum 1 to perform a developing operation of a desired color.

On the other hand, a transfer system 5 for transferring a developed image
Has a transfer drum 5b and a transfer discharger 5c disposed inside the transfer drum 5b. The transfer material brought into contact with the transfer drum 5b is developed by the transfer discharger 5c with toner developed on the photosensitive drum 1. And transfer the toner image from the photosensitive drum 1 to the transfer material at the transfer position. By repeating this transfer operation sequentially for each color toner, a full-color image is formed on the transfer material. The transfer material is supplied from the cassette 8 or the manual feeding unit 9, and is separated from the transfer drum 5 b by the separation unit 10 at the stage when the transfer is completed, and is conveyed to the fixing unit 11.
After the unfixed image on the transfer material is fixed, the image is stored on the tray 12.

FIG. 7 is a schematic configuration diagram showing an arrangement of the developing units 4Y, 4M, 4C, and 4BK in the toner supply device and a positional relationship between the toner hopper which is a storage section for each toner. As shown in FIG.
0 indicates that the yellow toner hopper 201Y, the magenta toner hopper 201M, the cyan toner hopper 201C, and the black toner hopper 201BK containing the color toner to be supplied to each developing unit are arranged in the same order corresponding to the developing units of each color. Is fixed to a support frame 202 provided in the vicinity of one end. In addition,
The support frame 202 is fixed to the apparatus main body.

Each toner hopper 201Y, 201M, 2
01C and 201BK, the toner outlets 203Y, 203M, and 203M respectively correspond to the positions of the toner receiving ports 400Y, 400M, 400C, and 400BK of the respective developing units.
203C and 203BK are provided.

Each toner hopper 201Y, 201M, 2
01C and 201BK are transferred to toner-conveying rollers 301Y and 301 each having a screw disposed therein.
M, 301C, and 301BK, the toner outlet 203
The toner is conveyed to Y, 203M, 203C, and 203BK and is discharged to the toner receiver of each developing unit. Here, depending on the position of the toner discharge port, for example, 300M
There may be a case where it is arranged in the horizontal direction like 300C and 300BK, and there is a case where it is arranged in the axial direction like 300Y. The installation direction of the transport path can be appropriately selected according to the space in the apparatus. it can.

Next, each toner hopper 201 shown in FIG.
Details of the toner supply device will be described with reference to a cross-sectional explanatory view when any one of the toner hoppers M, 201C, and 201BK is viewed from the longitudinal direction. As shown in FIG. 8, the toner stored in the toner hopper 201 is
The first screw 301 placed in the toner hopper conveys the toner in the direction of arrow A in FIG. As a result, the hopper corner 20 which is located farthest from the connection port 201a between the transport roller 300 and the toner hopper 201 is formed.
The toner in the vicinity of 1b is prevented from staying, and the volume of the hopper can be effectively used.

The connection screw 201 is provided by the first screw 301.
The toner transported in the vicinity of a enters the toner transport path 300 arranged along a direction perpendicular to the axis of the first screw 301, and the toner transport path 300 has the same axis as the axis of the first screw 301. The second screw 302 arranged along the orthogonal direction allows the second screw 30
The toner is conveyed in the axial direction of FIG. 2 in the forward direction of FIG. 8 and discharged from the toner discharge port 203 arranged at the end of the toner conveying path 300. A toner receiving port 400 is disposed at the lower end of the toner discharging port 203. The toner discharged from the toner discharging port 203 is supplied to the toner receiving port 400, and the toner received at the toner receiving port 400 is transferred into the developing unit 4 by a transport screw. Replenished.

In the toner hopper 201, a wire-shaped stirring member 303 is disposed above the first screw 301 and along the axial direction of the first screw 301. The stirring member 303 is locked on a stirring shaft 304 arranged along the axial direction of the first screw 301. The stirring shaft 304 and the rotation shaft of the first screw 301 are connected via a gear. By rotating the first screw 301 by a driving unit (not shown), the stirring member 303 rotates simultaneously with the first screw 301. It is designed to be driven.

The stirring member 303 is provided in the toner hopper 2
01 prevents the toner from aggregating. If the aggregated toner is replenished to the developing unit, a shortage of tribo locally occurs, or a uniform coating thickness on the developing sleeve is not obtained, and it is difficult to form a high quality image. It is.

With the toner supply device having the above-described configuration, it is possible to prevent the toner from staying in the toner hopper and agglomerating the toner, thereby realizing high-quality image formation.

When the remaining amount of toner in the toner hopper 201 becomes low, the user can be notified that there is no remaining toner by a signal from a toner remaining amount detecting sensor or the like (not shown). It has become.
The user who is notified that there is no remaining toner is shown in FIG.
The toner bottle 150 is placed in the toner hopper 2 as shown in FIG.
01, the toner bottle 1
From 50, toner is supplied to the toner hopper 201. At this time, in order to prevent toner aggregation, the toner bottle 150 is attached to the supply port of the toner hopper 201 after the toner bottle is shaken well to increase the fluidity of the toner.

In recent years, in order to pursue high image quality, the particle size of the toner has been reduced, the fluidity of the toner has been increased, and the behavior of the toner has been close to that of a liquid. In particular, it is highly fluid.

[0018]

However, in the above-described conventional toner supply device, the pressure at the toner discharge port of the toner hopper varies depending on the remaining amount of toner in the toner hopper. Even when the number of rotations is the same, the amount of toner supplied to the developing device may be different. When the amount of toner supplied to the developing device changes, the amount of toner and the toner density in the developing device change, causing a change in the density of the image.

The change in the toner supply amount to the developing device is as follows.
This is remarkable when highly shaken toner having high mobility is supplied from the toner bottle. FIG. 10 is a graph showing the relationship between the amount of toner supplied per rotation of the first screw and the amount of toner remaining in the toner hopper. Note that the horizontal axis in FIG. 10 indicates the remaining amount of toner in the toner hopper, and the vertical axis indicates the toner supply amount per one rotation of the screw. FIG.
0, the toner supply amount is 0.1 g / rotation when the toner is supplied stably, but when the toner is full in the toner bottle (toner weight 500 g), the toner supply amount is 0.1 g / rotation. Is twice as high as 0.2 g / rotation. Thereafter, the toner supply amount gradually decreases until the toner remaining amount becomes about 350 g, and the toner remaining amount becomes about 350 g.
g, the toner supply amount is stabilized at 0.1 g / rotation. As described above, when the remaining amount of toner in the toner hopper is large, for example, immediately after toner supply, the supply amount of toner is not stable.

The toner held on the blades of the screw gradually decreases due to the pressure caused by the rotation of the screw, the toner density becomes higher than that of the toner at the top of the toner hopper, and the fluidity is reduced. Although the screw is not packed in the blade, the screw is provided at the bottom of the toner hopper, so if there is a large amount of toner remaining, the toner weight and the toner portion in the screw blade will be reduced. As a result, the toner is unnecessarily packed in the blades of the screw without being balanced. According to FIG. 10, the weight of the toner in the upper portion of the toner hopper and the portion of the toner clogged in the blade of the screw are balanced by the remaining amount of toner of about 350 g. Becomes

Therefore, according to the present invention, the supply of the developer is stopped by stopping the operation of the transfer means in the developer supply device immediately after the supply of the developer and rotating the stirring member to collect the toner above the transfer means. Immediately after that, an object of the present invention is to provide an image forming apparatus which can stabilize the supply amount of a developer to a developing device, perform image formation without a change in image density or uneven density, and have a small loss time at the time of toner replenishment. And

[0022]

According to a first aspect of the present invention, an object of the present invention is to provide a latent image carrier for carrying a latent image, a developing device for developing the latent image, and a developer in the developing device. A developer supply device for replenishing the developer, the developer supply device is provided with a developer accommodating section for accommodating the developer, a conveying unit for conveying the developer in the developer accommodating section to the developing device, and a developer accommodating section. And an agitating means for agitating the developer, wherein the transporting means and the agitating means are driven by the same driving source. In the image forming apparatus, the developer supply device is provided between the driving source and the transporting means and the agitating means. This is achieved by providing a drive transmission unit that stops transmission of power to the transporting means for a predetermined time immediately after replenishing the developer with the developer and supplies power only to the stirring means.

Further, according to the second aspect of the present invention, the above object is achieved by providing a clutch between a drive source and a conveying means in a drive transmission unit to supply developer to a developer supply device. Immediately after that, for a predetermined time, this is achieved by driving only the stirring means by driving the driving means with the clutch disengaged.

Further, according to the third aspect of the present invention, the above object is to provide a drive transmission unit capable of transmitting rotation in only one direction from a drive source to a drive transmission unit between a drive source and a conveying means. This is achieved by driving only the stirring means for a predetermined time immediately after replenishing the developer to the developer supply device by selecting the rotation direction of the drive source and selecting the driven object by providing the means. You.

Further, according to the fourth aspect of the present invention, the above-described object is achieved by setting the time for stopping the transmission of power to the conveying means by the drive transmission unit from immediately after the developer is supplied to the developer supply device. This is achieved by setting a predetermined time after the start of image formation.

That is, according to the first aspect of the present invention, the transmission of the power to the conveying means is stopped for a predetermined time immediately after the developer is supplied to the developer supply device, and the power is supplied only to the stirring means. Is provided between the drive source and the conveying means and the stirring means, so that the developer in the lower part of the developer accommodating chamber is squeezed by the stirring means immediately after the developer is supplied, and the developer is supplied. Even when the developer weight is heavy immediately after, the supply amount of the developer is stabilized, and the image formation without the density change and the density unevenness during the image formation is performed.

Further, according to the second aspect of the present invention, the clutch provided between the drive source and the transfer means operates the drive source with the clutch disengaged so that only the stirring means is operated. Therefore, for a predetermined time immediately after replenishing the developer to the developer supply device, only the stirring unit is driven by driving the driving unit with the clutch disengaged, and the stirring unit is used immediately after replenishing the developer. The developer in the lower part of the developer storage chamber is closed, and the supply amount of the developer is stable even when the weight of the developer is heavy immediately after the replenishment of the developer, so that the image formation without the density change and the density unevenness during the image formation is performed. .

Further, according to the third aspect of the present invention, the drive transmission means provided between the drive source and the transport means and capable of transmitting rotation in only one direction from the drive source allows the drive source to be rotated. Since only the stirring means can be operated by selecting the rotation direction, only the stirring means is driven for a predetermined time immediately after the developer is supplied to the developer supply device, so that the stirring is performed immediately after the developer is supplied. By means of means, the developer in the lower part of the developer accommodating chamber is squeezed, and even when the developer weight is heavy immediately after the replenishment of the developer, the supply amount of the developer is stabilized, and the image formation without the density change and the density unevenness at the time of image formation can be performed. Done.

According to the fourth aspect of the present invention, the time for stopping the transmission of power to the conveying means by the drive transmission unit is set immediately after the supply of the developer to the developer supply device and after the start of image formation. By setting the predetermined time, the time during which the image formation is stopped when the developer is supplied is reduced.

[0030]

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

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration diagram of a developer supply device used in the image forming apparatus of the present embodiment. The developer supply device is disposed in the main body of an image forming apparatus such as a printer, a copying machine, a facsimile, and the like, and is disposed in the main body of the image forming apparatus with one or a plurality of developing units. The toner supply device can supply toner to each of the developing units. The configuration and operation of the photosensitive drum, corona charger, exposure optical device, developing device, transfer system, cleaning device, document reading system, and the like of the image forming apparatus are the same as those in the conventional example, and thus description thereof is omitted.

A developer supply device capable of replenishing the developing unit with toner, which is a developer, has a stirring means along a longitudinal direction of the toner hopper 10 at a lower portion in the toner hopper 10 which is a developer accommodating section for accommodating the toner. A certain stirring member 11 is provided, and a toner outlet 12 is opened on the bottom surface of the toner hopper 10. Further, a toner transport path 13 that is long along the longitudinal direction of the toner hopper 10 is provided below the toner hopper 10, and a toner receiving port 14 provided above one end of the toner transport path 13 is provided with a toner receiving port 14 of the toner hopper 10. A developing unit (not shown) is disposed corresponding to the opening of the toner discharge port 12 and is provided at an end of the toner transport path 13 opposite to the toner receiving port 14 side.
A toner supply port 15 is provided to form a developer supply device, and the toner from the toner hopper 10 can be supplied to the development unit via the toner conveyance path 13.

A stirring member 11 provided below the toner hopper 10 includes a stirring shaft 11a rotatably held by a housing of the toner hopper 10, and a plurality of stirring blades 11b having a long rod formed in a substantially spiral shape. It is configured to be locked,
The agitation member 11 is rotated in a predetermined direction by the operation of the drive motor 19 by being connected to a drive motor 19 serving as a drive source via a gear 20 constituting a drive transmission unit provided at one end of the agitation shaft 11a. The blade 11b can stir and compress the toner in the toner hopper 10.

In the toner transport path 13, the toner transport path 1
3 is provided with a screw 16 which is a conveying means for conveying the toner along the longitudinal direction. The screw 16 in the toner conveyance path 13 has a rotation shaft of the screw 16 rotatably held by a housing of the toner conveyance path 13, and one end of the rotation shaft is connected to the stirring shaft 11 a via the clutch 21 and the gear 22. When the drive motor 19 is operated with the clutch 21 connected, the stirring member 11 and the screw 16 are connected.
And can be simultaneously rotated in a predetermined direction.

If the drive motor 19 is operated with the clutch 21 disengaged, the screw 16 does not rotate and only the stirring member 11 rotates. The gear 20 provided on the stirring shaft 11a, the gear 22 and the clutch 21 provided between the screw 16 and the gear 20 are used for a predetermined time immediately after the toner is supplied to the developer supply device. The transmission of power to the screw 16 is stopped and the stirring member 1
A drive transmission unit capable of transmitting power to only one is configured.

In order to supply toner by the developer supply device having the above configuration, in a normal state, the drive motor 19 is operated with the clutch 21 connected, and the stirring member 11 is operated.
And the screw 16 are simultaneously rotated to feed the toner into the toner transport path 13 from the toner discharge port 12 of the toner hopper 10 while stirring the toner in the toner hopper 10, and the toner is transferred by the screw 16 in the toner transport path 13. It is supplied to a developing unit (not shown).

Here, when the supply of the toner from the toner hopper 10 to the developing unit advances and the remaining amount of the toner in the toner hopper 10 is exhausted, the toner is replenished into the toner hopper 10, and the toner hopper 10 is filled with the toner. Immediately after the toner is supplied to the toner hopper 10, the drive motor 19 is operated while the clutch 21 is disengaged for a predetermined time so that only the stirring member 11 is rotated. After a lapse of a predetermined time, the drive motor 1
9 is stopped, the clutch 21 is connected, and the stirring member 11 and the screw 16 are simultaneously rotated in the same manner as in a normal state to supply the toner to the developing unit.

As described above, immediately after the toner supply, the stirring member 1
By rotating only 1, the toner accommodated in the lower portion of the toner hopper 10 is compressed while being stirred by the stirring blades 11 b of the stirring member 11, and becomes scattered. By storing the toner in the lower portion of the toner hopper 10, the weight of the toner in the upper portion of the toner hopper 10 can be endured, and the toner supply amount can be stabilized even when the toner in the toner hopper 10 is almost full. be able to.

FIG. 2 is a flowchart showing the operation of supplying toner by the developer supply device, and the operation of supplying toner to the toner hopper will be described. The image forming apparatus
If it is detected that there is no remaining amount of toner during copying, image formation is temporarily stopped to protect devices such as a developing device. At this time, information indicating that there is no toner is displayed on a display unit or the like of the image forming apparatus to urge the user to supply toner.

When the user confirms that there is no toner,
When the toner is supplied to the toner hopper, the toner detecting means detects the presence of the toner, and after detecting the presence of the toner, the drive motor is operated with the clutch of the drive transmission unit being disengaged, and only the stirring blade in the toner hopper is rotated. Activate
At this time, since the clutch of the drive transmission unit is disengaged,
The screw does not operate, and the toner below the toner hopper is compressed by the stirring blade. Then, the rotation of the stirring blade is stopped after a predetermined time has elapsed since only the stirring blade was operated.

After the operation of the stirring blades is stopped, a message indicating that copying is possible is displayed on a display unit or the like of the image forming apparatus, and the user presses a start button or the control unit of the apparatus automatically restarts image formation. A signal is transmitted to a predetermined device to restart image formation. After resuming the image formation, the clutch of the drive transmission unit of the developer supply device is connected, and the screw is rotated together with the stirring blade in the toner hopper to supply the toner from the toner hopper to the developing unit.

FIG. 3 is a graph showing a toner supply amount when toner is supplied from a toner hopper by the developer supply device used in the image forming apparatus of the present embodiment. Note that the solid line in FIG. 2 indicates the developer supply device of the present embodiment, and the drive motor is operated with the clutch disengaged for a predetermined time immediately after the toner is supplied to the toner hopper, and only the stirring member is used. The broken line indicates the case where both the stirring member and the screw are driven for a predetermined time immediately after the supply of the toner. FIG.
As can be understood from FIG. 7, when the drive motor is operated in a state where the clutch is disengaged for a predetermined time immediately after the supply of the toner to operate only the stirring member, the toner in the toner hopper is compressed by the effect of the compression of the stirring blade 11a. When the remaining amount is 500 g, the toner supply amount is 0.13 g / rotation, and thereafter, the toner supply amount is stable at 0.1 g / rotation. It turns out that it can be done.

On the other hand, when both the stirring member and the screw are driven for a predetermined time immediately after the supply of the toner, as shown in FIG. , The toner supply amount is 0.2 g
/ Rotation, and thereafter, the supply amount of toner drops greatly, and is stable at 0.1 g / rotation. When the remaining amount of toner is large, the supply amount of toner is unstable, which may adversely affect image formation. You can see that there is.

As described above, in the present embodiment, the drive motor is operated with the clutch disengaged for a predetermined time immediately after the toner is supplied to the toner hopper, and only the stirring blade in the toner hopper is rotated. Since the toner is supplied after being opposed to the toner weight by squeezing the toner at the lower portion of the toner hopper, the toner supply amount from the toner hopper to the developing unit can be stabilized even immediately after toner replenishment. An image forming apparatus that can perform good image formation without image density fluctuation and density unevenness is provided.

Note that, instead of the clutch, a gear provided on the rotary shaft of the screw is slid along the direction of the rotary shaft so that the gear of the rotary shaft of the screw does not mesh with any gear. For a predetermined time immediately after replenishing toner to the toner hopper,
The gears of the rotary shaft of the screw may not be meshed with any gears.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. In the present embodiment, a one-way clutch is provided as a drive transmission means capable of transmitting rotation in only one direction from the drive motor, instead of the clutch of the first embodiment, and the rotation direction of the drive motor is selected, whereby the agitation is performed. It is possible to select whether to operate only the member or to operate both the stirring member and the screw. Note that a toner hopper, a drive motor, a screw, and the like having the same configuration as in the first embodiment are used, except that a one-way clutch is provided between the drive motor and the screw.

The developer supply device used in the image forming apparatus according to the present embodiment is provided with a drive transmission means for transmitting rotation in one direction from the drive motor between the drive motor and the screw. The drive transmission unit is configured so that only the stirring member can be operated by selecting the rotation direction. Specifically, as shown in FIG. 4, a one-way clutch 24 is disposed at one end of the rotation shaft of the screw 16, a gear portion 23 is provided on an outer peripheral portion of the one-way clutch 24, and a gear portion 2 is provided.
3 is meshed with a gear 20 provided at one end of the stirring shaft 11 a of the stirring member 11.

The one-way clutch 24 is configured such that the inner peripheral portion to which the rotating shaft of the screw 16 is connected rotates only when the outer peripheral portion rotates in one direction clockwise or counterclockwise. 19 rotation is gear 2
Whether or not the screw 16 rotates is determined according to the direction of rotation when transmitted to the gear portion 23 of the one-way clutch 24 via 0.

In this embodiment, by selecting the rotation direction of the drive motor 19, the stirring member 11 and the screw 1
6 can be rotated, or only the stirring member 11 can be rotated. The drive transmission unit using the one-way clutch allows the toner hopper 1
For a predetermined time immediately after replenishing the toner in the toner hopper 0, the drive motor 19 is rotated in a direction in which the screw 16 does not rotate, and only the stirring member 11 is rotated.
Close the bottom of the toner. After a lapse of a predetermined time, the rotation direction of the drive motor is reversed so that
By rotating both the screw 1 and the screw 16, the toner is supplied from the toner hopper 10 to the developing unit.

As described above, by using the drive transmission means for transmitting the rotation in one direction from the drive motor to the drive transmission section, the amount of toner supplied from the toner hopper to the developing unit can be stabilized with a simple configuration. Thus, an image forming apparatus that can perform good image formation without image density fluctuation and density unevenness can be obtained.

Note that, between the drive motor and the screw,
Although a one-way clutch is used as a drive transmission unit that transmits rotation in only one direction from the drive motor, the present invention is not limited to this, and a one-way clutch is used between the rotation shaft of the screw and the inner peripheral side of the gear provided on the rotation shaft. Alternatively, a ratchet mechanism may be interposed to transmit the rotation of the drive motor in only one direction to the screw.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. In this embodiment, in the first and second embodiments, image formation is stopped for a predetermined time after toner is supplied to the toner hopper, but image formation is restarted immediately after toner supply. Things. Except for restarting image formation immediately after toner replenishment, a toner hopper, a drive motor, a screw, or the like having the same configuration as in the first and second embodiments can be used.

In the present embodiment, as shown in the flowchart of FIG. 5 in which the image formation is restarted immediately after toner replenishment, the image forming apparatus detects that there is no remaining toner during copying, and The image formation is temporarily stopped for protection of the device such as. At this time, information indicating that there is no toner is displayed on a display unit or the like of the image forming apparatus to urge the user to supply toner.

When the user confirms that the display indicates that there is no toner,
When the toner is supplied to the toner hopper, the toner detecting means detects the presence of the toner, and after detecting the presence of the toner, the drive motor is operated in a state where the clutch of the drive transmission unit is disengaged. Is operated, and the toner below the toner hopper is compressed by the stirring blade. Immediately after the stirring member is activated, an indication that copying is possible is displayed on a display unit or the like of the image forming apparatus, and the user presses a start button, or a signal for restarting image formation is automatically issued from the control unit of the apparatus. Sent to the device
Image formation is resumed with the screw stopped.

After a lapse of a predetermined time from the operation of the stirring blade alone, the rotation of the stirring blade is stopped, the clutch of the drive transmission unit of the developer supply device is connected, and the screw is rotated together with the stirring blade in the toner hopper. By rotating, the toner is supplied from the toner hopper to the developing unit. Note that, instead of the clutch between the drive motor and the screw, as shown in the second embodiment, a one-way clutch is used for the drive transmission unit so that the screw is not operated by selecting the rotation direction of the drive motor. Is also good.

In this embodiment, the image forming apparatus can minimize the stop time of the copying operation and can form a good image without image density fluctuation and density unevenness. During a predetermined time after the start of the image formation, the toner supply from the toner hopper to the developing unit is stopped. However, since the detection of the absence of toner is normally detected with some margin, the absence of toner is detected. In this state, since some toner is present in the developing unit, there is no problem in image formation if the rotation of the screw is restarted and the toner is supplied while the remaining toner is present.

[0057]

As described above, according to the first aspect of the present invention, the transmission of power to the conveying means is stopped for a predetermined time immediately after the developer is supplied to the developer supply device. By providing a drive transmission unit that can transmit power only to the stirring means between the driving source and the conveying means and the stirring means, the developer in the lower part of the developer storage chamber is stirred by the stirring means immediately after the developer is supplied. In short, even when the developer weight is heavy immediately after the replenishment of the developer, the supply amount of the developer is stabilized, and the image forming apparatus can perform the image formation without the density change and the density unevenness during the image formation.

Further, according to the second aspect of the present invention, the clutch provided between the drive source and the transfer means operates the drive source with the clutch disengaged so that only the stirring means is operated. Therefore, for a predetermined time immediately after replenishing the developer to the developer supply device, only the agitating unit can be easily driven by driving the driving unit with the clutch disengaged, and the developer is replenished. Immediately thereafter, the developer in the lower part of the developer storage chamber is squeezed by the stirring means, so that even when the developer weight is heavy immediately after the replenishment of the developer, the supply amount of the developer is stable, and there is no density change or density unevenness during image formation. The image forming apparatus is capable of forming an image.

Further, according to the third aspect of the present invention, the drive transmission means provided between the drive source and the transfer means and capable of transmitting rotation in only one direction from the drive source allows the drive source to be rotated. Since only the stirring means can be operated with a simple configuration by selecting the rotation direction, the developer is supplied by driving only the stirring means for a predetermined time immediately after the developer is supplied to the developer supply device. Immediately after the developer is supplied, the developer in the lower portion of the developer storage chamber is squeezed by the stirring means. An image forming apparatus capable of performing image formation without any problem.

Further, according to the fourth aspect of the present invention, the time for stopping the transmission of power to the conveying means by the drive transmission unit is set immediately after the supply of the developer to the developer supply device and after the start of image formation. By setting the predetermined time, the image forming apparatus can reduce the time during which the image formation is stopped when the developer is supplied.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a developer supply device used in an image forming apparatus according to a first embodiment.

FIG. 2 is a flowchart when toner is supplied by the developer supply device of the embodiment.

FIG. 3 is a graph showing a toner supply amount when toner is supplied from a toner hopper by a developer supply device used in the image forming apparatus of the present embodiment.

FIG. 4 is a schematic configuration diagram illustrating a developer supply device used in an image forming apparatus according to a second embodiment.

FIG. 5 is a flowchart in the case where image formation is restarted immediately after toner supply according to the third embodiment.

FIG. 6 is a schematic configuration diagram illustrating a conventional image forming apparatus.

FIG. 7 is a schematic configuration diagram showing an arrangement of a developing unit in a conventional toner supply device and a positional relationship between each toner and a toner hopper.

FIG. 8 is an explanatory sectional view when the toner hopper is viewed from a longitudinal direction.

FIG. 9 is an explanatory cross-sectional view showing a state where a toner bottle is attached to a toner supply port on an upper portion of a toner hopper.

FIG. 10 illustrates a first screw 1 of the conventional toner supply device.
Graph showing the relationship between the amount of toner supplied per revolution and the amount of toner remaining in the toner hopper

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Toner hopper (developer accommodating part) 11 Stirring member (stirring means) 16 Screw (transportation means) 19 Drive motor (drive source) 20, 22 Gear (drive transmission part) 21 Clutch (drive transmission part) 24 One-way clutch (drive) Transmission means)

Claims (4)

[Claims] A developing device for developing the latent image; and a developer supply device for replenishing the developing device with a developer. A developer accommodating section for accommodating the developer, conveying means for conveying the developer in the developer accommodating section to the developing device, and stirring means for agitating the developer in the developer accommodating section. In an image forming apparatus driven by the same drive source, transmission of power to the transport unit between the drive source and the transport unit and the stirring unit for a predetermined time immediately after the developer is supplied to the developer supply device. An image forming apparatus provided with a drive transmitting unit capable of transmitting power only to the stirring means by stopping the operation. 2. The drive transmission unit, wherein a clutch is provided between the drive source and the transport unit, and the drive unit is disengaged for a predetermined time immediately after replenishing the developer to the developer supply device. The image forming apparatus according to claim 1, wherein only the stirring unit is driven by driving the image forming apparatus. 3. A drive transmission unit, wherein a drive transmission unit capable of transmitting rotation in only one direction from the drive source is provided between the drive source and the transporting unit, and the drive transmission unit selects a rotation direction of the drive source and receives the rotation. 2. The image forming apparatus according to claim 1, wherein only the stirring means is driven for a predetermined time immediately after the developer is supplied to the developer supply device by selecting a driving object. 4. The method according to claim 1, wherein the time for stopping the transmission of the power to the conveying means by the drive transmission unit is a predetermined time immediately after the supply of the developer to the developer supply device and after the start of the image formation. The image forming apparatus according to claim 1.