JPH04125670A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent an excess replenishment generated at the point of time when the replenishment is started by stopping the replenishment until the prescribed number of times of ON operation of a replenishing clutch can be counted after the level of a toner replenished in a replenishing mode temporarily gets to a target level. CONSTITUTION:The toner is conveyed to a first hopper while a sensor 52B which detects the amount of the toner is not operated when a drive transmitting means(replenishing clutch) 51C of a replenishing member(replenishing roller) 51B loaded in the first hopper is operated. Then, when the sensor 52B is operated, the replenishment of the toner to the first hopper is stopped until the number of outputting times of driving signals of the replenishing clutch 51C gets to the prescribed number of times, and it is switched into a slow toner replenishing cycle. Thus, the excess replenishment of the toner can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus, and more particularly to a toner replenishment control system for a developing device used in an image forming apparatus such as a copying machine.

(Prior Art) As is well known, in image forming apparatuses such as copying machines and printers, an electrostatic latent image formed on a photoconductor is processed using a two-component developer containing a mixture of toner and carrier, for example. A copy is obtained by processing a visible image using a photocopy process, transferring the visible image onto copy paper, and then fixing it.

One of the above-mentioned image forming apparatuses is a color copying machine that obtains a color image by superimposing images of different colors on the same copy paper, and the schematic configuration thereof will now be explained with reference to FIG. 6 as follows. .

That is, this color copying machine includes a scanner section 21 for reading originals, an image processing section 22 that electrically processes image signals output from the scanner section 21 as digital signals, and an image processing section 22 that electrically processes image signals output from the scanner section 21 as digital signals. a printer section 2 that forms an image on copy paper based on the image recording information of each color;
3.

The scanner part 21 described above includes a lamp 2 that illuminates the original placed on the original placing table 24 while moving in the scanning direction.
5, mirrors 26, 27, and 28 that set the optical path of the reflected light from the document illuminated by the lamp 25, and two imaging lenses that are arranged in this optical path and form an image on the dichroic prism 30. It includes a light receiver 31 that separates the reflected light from the document into colors and receives the light for each wavelength. In the above-mentioned scanner part 21, the dichroic prism 30 separates the reflected light from the document into three fills of colors, for example, red R, green G, and blue B, that is, the image light, and separates the colors of each wavelength. Light receiver to receive light, that is, CCD 31R for red, CCD 3 for green]G
, and the blue CCD 31B, and are converted into digital signals within the photoreceiver.

The digital signal described above is inputted to the image processing section 22,
The processing unit 22 performs the processing necessary for image forming exposure, which will be described later, to record information of each color, for example, black (hereinafter abbreviated as Bk), yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), The signals are converted into signals for recording each color of cyan (C).

Although FIG. 6 shows the case where the four colors Bk, Y, M, and C mentioned above are formed, the number of one color is of course not limited to this.

On the other hand, a signal from one image processing section 22 is input to the printer section 23, and is used to control the operation of the image exposure laser light emitting devices 328k, 32C132M, and 32Y according to each color.

The printer section 23 described above is a section that exposes image light from a document onto a photoreceptor, processes the electrostatic latent image formed by this exposure into a visible image using a developer, and then transfers it onto copy paper. It is.

That is, in the printer section 23, four sets of recording devices 338k, 33C133M, and 33Y are arranged side by side in the case shown in the figure.

Since each of the above-mentioned printing apparatuses has the same configuration, in order to simplify the explanation, the printing apparatus for C (cyan) will now be explained, and explanations for other colors will be omitted. Note that components having the same function for each color are given the same reference numerals, and in order to distinguish the configuration of each color, a subscript indicating each color is attached to the reference numeral.

That is, the C (cyan) recording device [33G has a photoreceptor 34C on a drum placed in the optical path from the laser beam emitting device 132c, and an image is formed around the photoreceptor 34C along the rotation direction. A charging device 35C1, a developing device 36C, a transfer device 37C, etc. for executing the forming process are provided in the same manner as in a known copying machine.

Then, the photoreceptor 3 is uniformly charged by the charging device 35C.
4C, a cyan latent image is formed by exposure by a laser beam emitting device 32C, and the latent image is processed into a visible image by a developing device 36C.

On the other hand, the printer section 23 is provided with a paper feed section for copy paper.
Copy paper having one of the various sizes selected is fed, and the leading edge of the copy paper is aligned with the leading edge of the image by the registration rollers 40, and then placed on the photoreceptor 3.
The direction of the conveyor belt 41 passing through the transfer position C is conveyed.

The copy paper carried on the conveyor belt 41 and conveyed to the transfer position of the photoreceptor 34C is sequentially conveyed to the photoreceptors 348k, 34C134M, and 34Y, which have been subjected to visible image processing. After the visible image of each color is electrostatically transferred by the action of the transfer device 37 provided opposite to the image forming apparatus, the visible image is conveyed from the conveyor belt 41 to the fixing roller 42 where it is fixed, and then transferred to the outside of the machine by the ejection roller 43. is discharged. The above-mentioned transfer belt 41 electrostatically attracts the copy paper it carries, so that the copy paper is transported at the speed of the belt without positional deviation.

By the way, the above-mentioned developing device has a structure using, for example, a two-component developer that is a mixture of resin toner and a magnetic carrier such as iron powder. A rotatable developing sleeve carries a magnetic brush, and the toner in the brush is transferred by electrostatic attraction from an electrostatic latent image on a photoreceptor. As for the structure, the seventh
There is a structure shown in the figure.

That is, the developing device fllA shown in FIG. 7 has a developing sleeve B arranged therein, and a developing tank C that supplies toner in the developer and a replenishing tank that temporarily stores replenishment toner. and, for example, a toner replenishment hopper D1 that is removably attached to the top surface of the replenishment tank, and the replenishment toner is
The supply roller E located at the outlet of the supply tank rubs against the surface of the supply roller F located near the developing sleeve B, and is supported on the surface of the supply roller F. The developing sleeve B is transported by the actuation of the member indicated by CL.

A replenishment bias circuit H for the replenishment toner is connected to the supply roller E, the replenishment roller F, and the blade G that contacts the surfaces of the replenishment roller F to thin the replenishment toner. teeth.

The amount of charge of the replenishment toner is corrected in accordance with the density change of the reference density pattern i formed on the photoreceptor (2).

Further, the toner replenishment hopper 01, which is removably installed in the replenishment tank described above, can communicate with the replenishment tank through a toner replenishment pipe located between the toner replenishment pipe and the toner replenishment pipe. When the provided toner conveying screw J rotates, the toner in the toner replenishment hopper Dl is dropped into the replenishment tank at approximately the center in the longitudinal direction of the replenishment tank.

Furthermore, an agitator K is disposed within the replenishment tank to agitate the toner dropped from the toner replenishment hopper D1 to uniformly disperse the toner within the replenishment tank.

On the other hand, in order to detect the amount of toner in the replenishment tank, a full sensor P composed of, for example, a level sensor is provided on the side wall of the replenishment tank, and detects the position of the upper surface of the toner. That's replenishment 4! The state of toner accumulation in D is detected.

In the developing device A having such a replenishment structure, toner replenishment is performed during image formation in the developing process, and as shown in FIG. 8, when the replenishment clutch is turned on, the supply roller E, The hopper motor (not shown) that rotationally drives the replenishment roller F, toner replenishment screw J, and agitator K starts rotating, and the toner level signal from the full sensor P reaches a low level (indicated by the symbol in FIG. 8). During this period, toner continues to be dropped from the toner replenishment hopper, and the replenishment clutch and hopper motor are stopped when the toner level signal from the full sensor P changes to a high level (indicated by H in FIG. 8).

The reason why the above-mentioned agitator K is not rotated all the time is to prevent toner from scattering from the gap between the joint and shaft of the replenishment tank housing if it is rotated all the time. When the toner in the toner replenishment hopper runs out, the toner end is detected by detecting the remaining amount using a level sensor installed in the toner replenishment hopper.When the toner level reaches a predetermined value or less, While the number of copies is being made, a warning is issued to prompt replacement of the toner supply hopper.

(Problem to be Solved by the Invention) By the way, in a developing device equipped with such a replenishment control 4iIi structure, the weight of toner in the replenishment tank increases over a target value over time, causing the agitator to overflow. Due to the increase in the torque and the increase in the load on the toner conveying screw J, there have been cases where the toner cannot be dropped and the toner becomes clogged. This phenomenon is particularly noticeable at high temperatures and high humidity, where the fluidity of the toner decreases.

When we investigated the cause of this phenomenon, we found the following.

Firstly, due to the decrease in fluidity, the toner level may be uneven between the position of the toner dropped into the replenishment tank by the toner conveying screw J and the position where the full sensor P is installed. Since the leveling by the agitator K does not work sufficiently, correction cannot be performed, and the response to the toner supply until the target value is detected by the full sensor P is delayed, and the During this period, more toner than the target value will be supplied.

Second, the toner level detected as being at the target value during agitation by the agitator may change to a lower level due to the weight of the toner when the agitator is not rotating, such as when the agitator is not replenishing or when the machine is stopped. be.

Therefore, even if the agitator K starts rotating again in the replenishment mode and the full sensor P resumes toner level detection,
Due to the delay in raising the toner level due to stirring, toner replenishment continues for a while after detection starts, in other words, until the toner level is detected to be at the target value.

Thirdly, while the toner existing within the rotation radius of the agitator is efficiently agitated, the lower part of the replenishment tank receives rotational force due to this rotation, which promotes the coagulation of the 1-toner. increases over time.

Regarding the first cause among the causes mentioned above, 1)
This can be countered by increasing the rotation speed of the agitator, or 2) changing the shape of the agitator to a larger one so that the stirring performance is even better than in the case described above.
When such measures are taken, the rotational torque of the agitator increases under normal conditions, and the change in toner level between when the agitator rotates and when it does not rotate increases, resulting in the above-mentioned second problem. There was a risk that a new problem would arise in that the second cause would be exacerbated.

In addition to the above-mentioned measures, it is possible to install the full sensor P even lower in the replenishment tank than before to lower the target value of the toner level. As the volume occupied by the replenishment toner becomes smaller compared to the volume inside the tank, a lot of wasted space is created in the replenishment tank, and furthermore, there is a surplus in the amount of toner in the replenishment tank after the above-mentioned toner end is detected. This creates a risk of damage to the supply roller, replenishment roller and blades that are in contact with each other.

Therefore, to deal with the second cause mentioned above, which may occur all the time, it may be possible to provide a time lag between the start of rotation of the agitator and the start of detection by the full sensor. The time becomes short, and replenishment followability, especially for small-sized images, is sacrificed.

Furthermore, constantly rotating the agitator tends to cause toner to scatter to the surroundings as described above, and also promotes coagulation.

SUMMARY OF THE INVENTION In view of the above-mentioned problems with the conventional developing device, particularly the toner replenishment structure, an object of the present invention is to provide an image forming apparatus equipped with a toner replenishment structure that can solve the above-mentioned causes with a simple configuration. .

(Means for Solving the Problems) In order to achieve this object, the present invention provides a first hopper that is provided integrally with a developing device, a sensor that detects the amount of toner in the first hopper, and a sensor that detects the amount of toner in the first hopper. An image forming apparatus comprising: a second hopper provided separately from the first hopper; and a toner conveying means for conveying toner from the second hopper to the first hopper based on a detected value of the sensor. A sensor and a density sensor for detecting the toner density on the photoreceptor subjected to visible image processing by the developing device are installed on the input side, and on the high-force side, the swinging portion of the toner conveying means and the first hopper are installed. The controller includes a control unit connected to each of the drive transmission means of the replenishment member, and the control unit detects the amount of toner when the drive transmission means of the replenishment member is operating in response to a signal from the density sensor. After the sensor detects a predetermined amount of toner and stops toner conveyance to the first hopper, the number of outputs to the drive signal of the drive transmission means of the replenishment member is determined regardless of the output of the toner amount detection sensor. It is characterized in that the supply of toner to the hopper of the cylinder 1 is stopped until the number reaches a predetermined number.

(Function) According to the present invention, when the drive transmission means of the replenishment member installed in the first hopper is operating, and the sensor for detecting the amount of toner is not operating, the toner is supplied to the first hopper. When the toner is transported and the sensor is activated, toner replenishment to the first hopper is stopped until the number of outputs of the driving signal of the drive transmission means reaches a predetermined number, and the slow toner transport is stopped. Switch to replenishment cycle.

(Embodiment) Hereinafter, details of an embodiment of the present invention will be explained with reference to FIGS. 1 to 5.

FIG. 1 is a schematic diagram corresponding to FIG. 7 showing a developing device of an image forming apparatus according to an embodiment of the present invention.

The developing device 50 shown in FIG. 1 has a structure similar to that shown in FIG.
A first hopper 52, which is composed of a developer tank 51 having A therein, and a supply tank for temporarily storing toner;
The main hopper 53 is detachably attached to the first hopper 52 and includes a main hopper that drops and replenishes toner to the first hopper 52 by means of a toner conveying screw 53A.

Then, the replenishment toner is rubbed onto the surface of the replenishment roller 51B located near the developing sleeve 51A by the supply roller 52A located at the exit of the first hopper 52, and is carried on the surface of the replenishment roller 51B. When the replenishment clutch 51C is operated, the toner is transported to the developing sleeve 51A.

Further, the replenishment of toner from the second hopper 53 to the first hopper 52 is performed by a fullness sensor 52B consisting of a level sensor provided in the first hopper 52 when the above-mentioned replenishment clutch is activated. This is done by rotating and dropping the toner conveying screw 53A until it is detected that the level of the toner has reached a predetermined position.
The toner dropped into the hopper 52 is transferred to the agitator 52.
It is uniformly dispersed by the rotation of C.

On the other hand, the above-mentioned replenishment roller 51B involved in toner replenishment,
Replenishment clutch 51C1 supply roller 52A, agitator 5
2C and the toner conveyance screw 53A are driven and controlled by a control section 54, which will be described later.

That is, as shown in the second diagram, the control unit 54 is composed of a microcomputer (CPU 54^) that performs arithmetic control, and this microcomputer 54A runs a basic program and a basic program for executing arithmetic control processing. It is equipped with a ROM 54B for storing data and a RAM 54G for temporarily storing data, and is connected to external equipment via an I10 interface 54D.

The input port of the above-mentioned I10 interface 54D is connected to a density sensor 55 that detects the density of the reference density pattern on the photoreceptor, a full sensor 52B provided in the first hopper 52, and a counter that counts the number of activations of the replenishment clutch 51C. A counter 56 is connected thereto.

The output boat is provided with a replenishment clutch 51G, a replenishment clutch 51C, and a hopper motor drive unit 5 that performs one rotation of the replenishment rotating members including the above-mentioned rollers.
7 are connected to each other.

In the microcomputer 54A, processing is executed based on the flowchart shown in FIG.

That is, this flowchart shows toner replenishment processing in the image forming sequence program of the copying machine, and when toner replenishment is required based on a signal from the density sensor 55, the replenishment clutch 51C is activated.
In response to this, the full sensor 52B detects the toner level.

In this embodiment, when the toner level measured by the full sensor is at the target value, it is designated as (H), when it is below the target value, it is designated as (L), and when the toner level is at the target value, the hopper motor is disabled. A hopper flag for activation is set, and execution of replenishment control is determined by determining whether the hopper flag is in either (H) or (L).

That is, in FIG. 3, the hopper flag is determined,
When the hopper flag is (L), the full sensor 52B
In other words, during the period when the replenishment clutch 52C is operating, until the toner level measured by the full sensor 52B reaches the target position.

The hopper motor is activated to continue replenishing toner until the flag identifying the toner level by the full sensor 52B changes to (H).

Further, when the above-mentioned full sensor 52B is (H),
When the hopper motor is stopped, set the hopper flag (H
).

When the hopper flag is determined to be (H), in other words, when the toner level is at the target position, toner replenishment via the hopper motor lV movement is stopped during subsequent activation of the replenishment clutch. count the number of times the 1z motion signal is output to the replenishment clutch 51C, and until this number matches a predetermined number, 20 times in this embodiment, the output to the first pumper 52 is performed regardless of the output of the full sensor 52B. Toner replenishment is stopped, and when a predetermined number of times has been reached, toner replenishment operation is restarted.

In other words, this process is aimed at preventing toner from being inadvertently replenished when the toner level reaches the target.

That is, the change in the amount of toner replenishment shown by the solid line in FIG. 4 is due to the conventional structure, and in this case, as explained as the second cause above, the replenished toner level is agitated by the agitator. After reaching the target value during the operation, it becomes lower due to its own weight when the agitator is not replenishing or when the agitator is not rotating.

Even if the agitator starts rotating again in replenishment mode and the level detection by the full sensor resumes, the increase in level due to stirring is delayed, so toner replenishment continues during that time and the replenishment toner exceeds the predetermined replenishment amount. When the toner weight reaches the target value, the weight of the toner exceeds the target value, so-called excessive replenishment occurs.

On the other hand, in this embodiment, −
As shown by the dotted chain line, when it is detected that the -degree toner level has reached the target position, the toner replenishment operation is not performed until the replenishment clutch has been turned on a predetermined number of times. In other words, the duty cycle for the replenishment operation is increased to prevent the toner from exceeding a predetermined replenishment amount, thereby preventing excessive toner replenishment.

Since the present embodiment has the above configuration, as shown in FIG. 5, when the hopper motor flag obtained from the output from the full sensor 52B is at (H), the replenishment clutch 5
The hopper motor is stopped and the process explained in FIG. 4 is executed until the number of ON signals of 1C (in FIG. 5, 3 times is shown due to space constraints) has elapsed, and the replenishment is continued. When the clutch 51C turns on,
In the replenishment mode, the first hopper 5 is activated by activating the hopper motor in response to the ON operation of the replenishment clutch 51C.
In the second direction, toner supply from the second hopper 53 is resumed.

(Effects of the Invention) As described above, according to the present invention, once the level of toner replenished in the replenishment mode reaches the target level, replenishment is stopped until a predetermined number of ON operations of the replenishment clutch are counted. By doing so, even if the level of the replenished toner becomes low due to its own weight, it is possible to prevent excessive replenishment from occurring at the time when replenishment is started.

Further, according to the present invention, as described above, while the replenishment clutch is turned on a predetermined number of times, replenishment can be stopped regardless of the on operation, so that the amount of toner can be periodically adjusted. This allows for better fluidity of the toner in the middle layer in the first hopper, and reduces the pressure on the lower layer, thereby suppressing toner coagulation.

Furthermore, since the agitator is agitated only during replenishment, toner coagulation is not promoted, and as a result, the position of the agitator is not restricted.

As described above, according to the present invention, all the problems that have occurred in conventional structures can be solved with a simple configuration, and problems such as abnormal increase in torque of rotating members such as agitators can be prevented. An image forming apparatus equipped with a toner replenishment structure can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a layout diagram showing a schematic configuration of a developing device of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram for explaining the configuration of a control section used in the developing device of FIG. 1, and FIG. The figure is a flowchart for explaining the action of the control section shown in Fig. 2, Fig. 4 is a diagram for explaining the action of the control part shown in Fig. 2, and Fig. 5 is a flowchart for explaining the action of the control section shown in Fig. 2. FIG. 6 is a schematic configuration diagram for explaining an example of an image forming apparatus, and FIG. 7 is a diagram of a developing device used in the apparatus shown in FIG. 6. FIG. 8 is a layout diagram showing a schematic configuration and a timing chart for explaining the characteristics of the developing device shown in FIG. 7. 50... Developing device, 51... Developer tank, 52... First hopper, 51C... Supply clutch, 52B...
・Full sensor. 53...Second hopper, 53^...Toner transport screw, 54...Control unit, 57...Hopper motor drive (1 other person) Fig. 4 Figure 7

Claims (1)

[Claims] A first hopper provided integrally with the developing device and the first
a sensor for detecting the amount of toner in the hopper; a second hopper provided separately from the developing device; and conveying the toner from the second hopper to the first hopper based on the detected value of the sensor. In an image forming apparatus, a density sensor for detecting the toner density on a photoreceptor subjected to visible image processing by the sensor and the developing device is provided on the input side, and the toner transport means is provided on the output side. and a control unit connected to a drive unit for the replenishment member and a drive transmission unit for the replenishment member installed in the first hopper, and the control unit controls the drive transmission unit for the replenishment member in response to a signal from the concentration sensor. is operating, the toner amount detection sensor detects a predetermined amount of toner and the first
After stopping the conveyance of toner to the hopper, regardless of the output of the toner amount detection sensor, the first operation continues until the number of outputs of the drive signal to the drive transmission means of the replenishment member reaches a predetermined number. An image forming apparatus characterized by stopping supply of toner to a hopper.