JPS6343183A - Image forming device - Google Patents

Abstract

PURPOSE:To set up the density of an image reproduced on paper to an always proper value by allowing a copying machine to execute image forming operation by a CPU during tonner feeding operation when an external input for commanding the image forming operation to a copying machine exists during the non- steady replenishing operation. CONSTITUTION:If a print switch 92 is depressed when a forced toner replenishing request flag is led by turning on a toner replenishing switch 91 and toner is replenished non-steadily, the CPU allow the copying machine to execute image forming operation during the switching. When a non-steady toner feeding is commanded, toner density detected by a toner density sensor 11 is compared with a reference toner density value and toner is continuously replenished to a developing device until the detected density exceeds set point. Consequently, the developed image density can be prevented from being thinned due to the drop of toner density.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus with an improved toner replenishment method.

The image forming apparatus of the present invention is used in copying machines, laser printers, and the like.

[Prior Art] Generally, in copying machines, laser printers, etc.
2. Description of the Related Art An image forming apparatus is used in which an electrostatic m-image formed on a photoreceptor is visualized using toner in a two-component developer, and the toner image can be transferred to copy paper or the like.

In such an image forming device, as the electrostatic latent image is developed,
Since the toner contained in the inter-track developer stored in the developing container is consumed and reduced, it is necessary to replenish it at any time.

Therefore, in the past, a magnetic sensor was installed in the developing device, and the toner concentration in the developer was detected by utilizing the change in inductance of the coil that constitutes the magnetic sensor due to changes in the toner concentration in the developer. , a method for replenishing toner to the developer when the developing device is operated according to this detected value; 2. As a pre-copy process, for example, a reference chart having a constant image am is used to control the toner replenishment; A known method is to form a Ti latent image on the surface of a photoreceptor, develop it, optically detect the developed density, and replenish toner to the developer when the image is near the developing device according to this detected value. .

[Problems to be solved by the invention] However, the toner ffi supplied by these methods
is set based on the amount of toner consumed by an image forming operation using a document having a standard image density.

Furthermore, toner replenishment operations using these methods are performed within a limited short period of time, such as during an image forming operation.

For this reason, for example, when documents with dark images continue, toner consumption becomes excessive, and the toner concentration (or current density) in the developer falls below the predetermined setting (Iff), and toner replenishment continues. However, since toner replenishment is stopped within a short time, the toner concentration in the developer in the developer container may not recover to the predetermined setting value.As a result, the density of the copied image may continue to be low. become.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an image forming apparatus that can conveniently replenish an appropriate amount of toner as needed.

[Means and effects for solving the problems] The image forming device of the present invention includes a developing device that visualizes an electrostatic latent image with toner, and a toner concentration in a two-component developer in the developing device. a toner concentration detecting means for detecting; a toner replenishing means for replenishing the developer with toner while the developing device is in operation; and a non-regular replenishing operation different from the replenishing operation by the toner replenishing means. an input means; and control for driving and controlling the toner replenishing means to continue the replenishment operation while the detected toner concentration is lower than a predetermined set value when a replenishment operation is commanded by the input means; means and
In the image forming apparatus, the III If means is configured to perform the operation (11 Wj This is what allows you to execute the following.

That is, in the above configuration, when non-regular toner replenishment unrelated to toner replenishment performed during an image forming operation is commanded by the input means, the toner density detected by the toner density detection means does not reach a predetermined value. Continue toner supply until the set value is reached. Thereby, the toner density is maintained at an appropriate density. Furthermore, the command operation is simple because it only needs to be performed once.

Furthermore, when an external input instructing an image forming operation is received during the non-regular replenishment operation, the image forming operation is executed during the non-regular replenishment operation. Thereby, the image forming operation can be executed at a desired time regardless of the replenishment operation.

[Example 1] The present invention will be described below with reference to specific examples shown in the drawings.

(Description of the copying machine body) First, the mechanical configuration and copying principle of the copying machine to which the present invention is applied will be explained.

FIG. 1 is a perspective view showing the appearance of the main body of the copying machine of this embodiment, and FIG. 2 is a schematic diagram illustrating the structure of the vicinity of the developing device of the copying machine.

The copying machine of this embodiment has an optical system 5 that scans the original for exposure and continuously projects a light image corresponding to the original onto the surface of the photoreceptor drum.
(50-55) and the projected light image is static? I! An electrostatic recording section 6 (61 to 69) records a latent image on the photoreceptor drum.
) and a developing device V! which visualizes the static 'W1 latent image on the photoreceptor drum 61 with toner. 4 (40 to 45), a transfer unit 7 (71 to 72) that transfers the visualized toner image onto copy paper, and a paper feed/discharge system and fixing device that supply copy paper and fix the image. (Ministry illustration) and 4 manuscripts!
It has a glass document table 8 on which to place documents, and performs predetermined operations and displays by detecting various key inputs (see operation panel 9 in FIG. 1) and sensor inputs.

(a) Optical system 5 The optical system 5 includes a light source 5o and mirrors 51, 52, 53, 54.
It has a lens 55 and a drive mechanism (not shown), and moves back and forth along the lower surface of the document table 8, and exposes and scans the surface of the document during forward movement. That is, the reflected light from the original is reflected by mirrors 51 and 52.
．． 53, passes through a lens (variable magnification lens block) 55, is further reflected by a mirror 54, reaches a photosensitive drum 61, and an optical image corresponding to the original is projected onto the surface of the drum 61.

The mirrors 51, 52, and 53 are connected to the same exposure scanning motor (
(not shown).

The moving speed is relative to the circumferential speed V of the photoreceptor drum 61.
The light source 50 and mirror 51 are V/N (N: copy magnification)
The mirrors 52 and 53 are V/2N in order to keep the optical path length constant. On the other hand, the mirror 54 and the lens 55 are driven in conjunction with each other by a magnification setting motor (not shown). Here, the lens 55 moves on the optical axis to change the copying magnification, and the mirror 54 moves and changes the Jff
i and correct the imaging point.

(b) Electrostatic Recording Unit 6 The electrostatic recording unit 6 includes a photosensitive drum 61 that can be rotated in the direction of the arrow, a main eraser lamp 62 arranged around the drum 61, a sub-charging charger t63, and a sub-eraser. It has a lamp 64, a main charger 65, and six blade-type cleaning devices.

A photoreceptor layer is formed on the surface of the drum 61, and the photoreceptor layer is sensitized and charged by passing through the eraser lamp 62, 64 and the charging charger 63, 65, and is projected from the optical system 5. The electrostatic latent image is formed by continuously receiving the optical image in the form of Surin 1.

(C) Developing device 4 The developing device 4 includes a developing sleeve 42 and a developing sleeve 4.
This is a magnetic brush type device equipped with a magnetic roller 41 built into the magnetic roller 2 and a built-in magnetic roller 41. The developing sleeve 42 has its axis parallel to the axis of the photoreceptor drum 61, and its outer surface faces the outer surface of the photoreceptor drum 61 with a predetermined gap, so that the developing sleeve 42 is inserted into the developer container 45. It is located in In addition,
A developing bias power source 40 is connected to the developing sleeve 42 via a self-bias resistor RO. Further, as the developer, a two-component developer consisting of toner and magnetic carrier is used.

A toner tank 43 is arranged above the developer container 45,
By rotating the toner replenishment roller 44 installed at the bottom of the toner tank 43, the toner tank 43 is removed through a notch formed around the toner replenishment roller 44.
The toner inside is supplied to the developer container 45. Therefore, the amount of toner supplied per rotation of the toner supply roller 44 is constant.

Further, a toner depth sensor 11 is disposed at a predetermined location within the developer container 45, and transmits an electrical signal at a level corresponding to the toner concentration at the predetermined location to the control circuit 2 via the toner concentration detection circuit 1. ing.

Here, the toner concentration sensor is a magnetic sensor that detects the magnetic permeability of the developer.

The control circuit 2 is mainly composed of a microcomputer, as will be described later, and is used when the development '4A sword is operated (at the time of image creation).
In order to carry out regular toner replenishment and non-regular toner replenishment based on the input signal from the toner replenishment switch 91 (FIG. 1), the replenishment roller is driven in accordance with the detection signal from the toner concentration sensor 11, etc. Controls mechanism 3.

(d) The image visualized by the transfer portion 7 etc. 1 to ner is transferred to the transfer charger 7
1, the copy paper is electrostatically transferred onto a copy paper, and the copy paper is transferred to a photoreceptor drum 61 by a separation charger 72.
separated from The copy paper is guided to the transfer section 7 by a paper feeding device (not shown), and then is discharged from the copying machine via a fixing device (not shown).

(Description of Control Circuit 2) FIG. 3 is a circuit diagram showing details of the control circuit 2 shown in FIG. 2.

As shown in the figure, the control circuit 2 has a CPU 20 consisting of a one-chip microcomputer, and the CPtJ20 has a
It is connected to other input/outputs and other microcomputers via an interface 21.

The output port PAO of the CPU20 has a driver]C31
A solid state relay (SSR) 32 is connected through the 25V AC power supply 34, and the toner supply motor 3
The configuration is such that it can drive 3. The drive is PAO
The output signal level from is performed in a low level state.

Further, a solid state relay (SSR) 402 is connected to the output boat PA1 via a driver IC 401, and a developing motor 40 is connected to the output boat PA1 by an i oov AC power supply 404.
3 (the developing motor drives the developing sleeve, magnetic roller, developer stirring member, etc.). Note that driving is performed when the output signal level from PAl is at a low level, as described above.

Further, a replenishment request display LED (see Fig. 1) 96 is connected to the output boat PA2 via a driver IC 960, and is configured to be lit when the output signal level from PA2 is at a low level. .

On the other hand, the input boat PBO has a toner replenishment switch 91 (
(see FIG. 1) is connected, and the on state of the switch 91 is inputted to P[30 as a low level signal.

Further, a toner concentration sensor 11 is connected to the input boat FBI via a toner concentration detection circuit 1, and when the detected toner concentration is lower than a predetermined setting value (a toner concentration of 5 wt% in the wooden embodiment), This state is input to the PBI as a high level signal.

In addition, there is a print switch 9 on the input capo-1-P B2.
2 (see FIG. 1) is connected and the switch 92 is turned on, a low level signal is input to PB2.

Furthermore, the input boat PB3 has a clear/stop key 9.
3 (see FIG. 1) is connected, and the on state of the switch 93 is represented as a low level signal. The clear/stop key 93 is a key that commands to stop the copy operation and clear the set number during copying, and commands to stop toner replenishment while the toner replenishment switch 91 is replenishing toner.

(Operation explanation) The operation of the apparatus of this embodiment will be explained below.

FIG. 4 is a flowchart showing the main routine of the CPU 20.

The CPU 20 starts processing when the power is turned on, and
After setting the initial state in step 02, a routine timer that defines the time for one routine is set (S104).

Next, in 8106, input processing of signals from various keys and sensors is executed. Note that input processing related to toner replenishment will be described in detail in the explanation of FIG. 5.

Next, in 3108, toner replenishment processing is executed.

Details of the toner replenishment process will be explained based on FIG. 6.

Next, at 8110, processing related to the copying operation is executed. Regarding this process, after the copy operation inquiry start flag, which will be described later, is set, the flag is cleared when a series of processes is completed.

Thereafter, the process waits for the routine timer set in 8104 to end and returns to 5104 (S112).

FIG. 5 is a flowchart showing details of input processing related to toner replenishment.

First, each flag mentioned in the following processing description will be explained.

Flag mini strong υ1 toner replenishment request flag; set when toner replenishment switch 91 is turned on.

Flag b = strong! 11 Toner replenishment request continuation mode flag;
It is activated when the print switch 92 is turned on during forced toner replenishment.

Flag C: Low constant replenishment mode flag: Set when toner concentration is normal.

Flag d: Toner supply mode flag; stands when the toner concentration is low.

As shown in FIG. 5, first, it is determined whether or not the strong 1111 toner replenishment request mode is in effect (S202).

That is, the state of the strong υ1 toner replenishment request mode flag a is determined.

Next, in 3204, it is determined whether or not there is an input to the print switch 92. Specifically, the input port PB of the CPU 20
Determine the signal level of 2. Low level is on.

If the input of the print switch 92 is detected in the forced toner replenishment request mode in the judgment in step 5204, flag b is set to set the forced toner replenishment request continuation mode in step 5206>, and the copy operation process is executed. A copy operation start flag is set (8208). in particular,
At 5110, driving the optical system 5 and photosensitive drum 61, transferring and fixing onto copy paper, ejecting the copy paper, etc.
A process for controlling the main operation of a copying machine is executed by setting a copy operation start flag.

Although omitted from the illustrated flow, when the print switch 92 is input in a mode other than the forced toner replenishment request mode, a separate copy #71 start flag is set.

As described above, through the processes 5202 to 5208, if the print switch 92 is pressed during non-regular toner replenishment due to the input of the toner replenishment switch 91, a copying operation is executed during toner replenishment.

In this case, the toner replenishment operation in the forced toner replenishment request mode is continued. Also, during the copy operation,
The replenishment request LED 96 is lit.

At 8210, it is determined whether there is an input to the toner replenishment switch 91, and if an input is detected, a flag a is set and a strong i! III Set toner replenishment request mode 5212
), lights up the replenishment request display LED 96 (S214).

Here, if the forced toner replenishment mode is set, a timer for rotating the developing motor for a predetermined period of time should be set 5216>, and the developing motor should be turned on (S218>. Turning on the developing motor is for toner density measurement. This is to eliminate variations in toner concentration in the developer by mixing and stirring the developer in advance.The presence or absence of an input to the toner replenishment switch 91 is determined by the signal level to the input port PBO of the CPU 20. Furthermore, the replenishment request display LED 96 is turned on by setting the signal from the output port PA2 to a low level.

As described above, input processing related to toner replenishment is executed.

FIG. 6 is a flowchart showing details of toner replenishment processing.

First, in 5302, it is determined whether the copying machine is in the process of copying. 5 if it is determined that a copy operation is in progress
312, and sets the toner replenishment mode or low constant replenishment mode according to the detected toner density (33
12 to 5350). That is, if a copy operation is executed during toner replenishment in the forced toner replenishment request mode, this toner replenishment is continued.

If it is determined that the copy operation is not in progress, the process advances to 8304 and the state of the flag b is determined. That is, it is determined whether or not the forced toner replenishment request continuation mode is in effect 1i.

As a result of the determination, if flag b=1, that is, if it is the forced toner replenishment request continuation mode, the process advances to 8306, where flag a is set and the forced toner replenishment request mode is set.

This is because the toner concentration in the developer is measured again after the copy operation process started in step 8208, and if the copy operation process ends with the toner concentration still decreasing, unsteady toner This is to enable replenishment.

Then, the process advances to step 8308, where it is determined whether or not the forced toner replenishment request mode is in effect. Note that if the result of the determination at $304 is that it is not in the forced toner replenishment request continuation mode, the process directly proceeds to 5308.

As a result of the determination in 8308, if flag a=Q, that is, if the forced toner replenishment request mode is not in effect, 8362
Proceed to. Immediately, if the mode is not the forced toner replenishment request mode, the toner replenishment operation is terminated when the copying operation process is completed. In other words, regarding regular toner replenishment, toner replenishment is not performed after the copying process is completed, regardless of the toner concentration of the developer.

If it is determined in 5308 that the mode is the forced toner replenishment request mode, the condition that there is no replenishment stop request (
In S310), the process advances to 5312. Note that a replenishment stop request is a request made to the CPU 20 when toner replenishment is not completed or toner replenishment is prohibited due to an empty state of the toner tank 43, input of the clear stop key 93, etc. This is a request made by

5312 to 8350 (Part 2 in Figure 6) have a toner replenishment mode that compares the detected toner concentration with a set value and replenishes toner according to the result, and a toner replenishment mode in which the toner is scattered outside the developing device in the form of powder smoke. This process sets a low quantity replenishment mode in which toner that is inevitably consumed is replenished regardless of the development of the ffi latent image.

First, in step 5312, the number of density determinations up to the previous time is checked. "Concentration determination" refers to a comparison between the toner concentration detected by the toner concentration sensor 11 and a set value;
This corresponds to determination 5318, which will be described later.

As a result of the determination, if this is the first time, the violation is confirmed at 8314 as having waited for a predetermined interval (set to 200 m5ec in the Thursday example) since the previous "concentration determination".
Proceeding to S316, it is determined based on flag C whether the low quantity replenishment mode is set. As a result, if it is determined that the low constant damage supply mode is set, the specified ■
Replenish the toner (, jump to S'317 to $350 and proceed to 8362. [Predetermined F1i toner] refers to toner that is not electrostatically charged, such as scattering outside the developing device in the form of powder smoke). This refers to a small amount of toner that is estimated to be inevitably consumed regardless of the development of a latent image, and the predetermined amount is defined by an inter-hypothetical replenishment timer.

In 8316, if flag c=Q, that is, if it is determined that it is not the low quantity replenishment mode, after waiting for the timer set in 8216 to end (S317), 5318
Then, the detected toner density is compared with the set value. Specifically, the level of the signal input from the toner concentration sensor 11 to the input port PB1 of the CPU 20 via the toner concentration detection circuit 1 is determined. Note that the determination in step 5317 as to whether or not the timer has ended is made only during the toner replenishment operation in the forced toner replenishment request mode.

When the input signal level is high level, it means that the detected toner concentration is lower than a predetermined setting value, and the process proceeds to 5320, where a counter ('7M degree U light J counter) that counts when the detected toner concentration is low is set. After incrementing by 1, proceed to 5322. On the other hand, in the case of low level, that is, when the detected toner concentration is higher than the predetermined setting value, directly 5
Proceed to 322.

In S322, the density determination counter is incremented by one. Note that this counter is used to check the number of times the check is made once in step 5312.

As a result of the determination in step 5312, if the number of density determinations up to the previous time is 1 to 4, the process proceeds to step 8318 and subsequent steps, and the detected toner density is checked in the same manner as described above.

As a result of the 'F11 constant in 5312, if the number of judgments has reached 5 times until the previous time, the process proceeds to 5330.
After clearing the density determination counter, the toner supply motor 33 is turned on at 3332. That is, the output boat PAO
The output signal level from is set to low level. As a result, replenishment of toner from the toner tank 43 into the developer container 45 can be started.

Next, in 5334, the magnitude of the detected toner concentration and the set value is determined. That is, the past five toner density determinations (331
8), if the number of times the detection 11a is determined to be "light" exceeds the majority, it is determined that the detected toner density is lower than a predetermined setting value, and the process proceeds to step 5350, where the toner replenishment mode is activated. Set flag d to set toner replenishment mode. As a result, toner replenishment continues while the toner replenishment mode is set (that is, the period in which the "detected toner concentration <setting value" continues to be determined in step 5334). Therefore, the amount of toner required to increase the toner level up to the set value is replenished. If anything,
This is because the toner replenishment motor 33 is turned on at 5332, and this state continues until the toner replenishment mode and the low constant replenishment mode are canceled.

As a result of the determination in step 5334, if the number of times the density is "light" in the past five determinations (determination in S318) is less than the majority, the detected toner concentration is higher than the set value, and therefore, the toner is substantially It is determined that there is no need for replenishment, the process proceeds to 8336, sets the low quantity replenishment timer to a predetermined time, then proceeds to 5338, sets the low constant replenishment mode flag C and sets the low quantity replenishment mode, - and , the toner replenishment mode is canceled (8340). As a result, toner is replenished until the low quantity replenishment timer is counted up (see 8366). That is, the above-mentioned constant amount of toner is replenished.

Then, proceed to 5342 and clear the density "light" counter. Note that the toner replenishment operation in the toner replenishment mode and the low constant replenishment mode may be aborted at the time when the copying operation process is completed (for example, after the autoshield is completed) if the forced toner replenishment request mode is not set.

On the other hand, when the forced toner replenishment is in the demand mode, the replenishment operation is terminated after the toner replenishment operation is completed unless there is a request to stop the replenishment.

8362 to 3382 (Part 3 in FIG. 6) are steps for controlling the duration of toner replenishment, etc.

That is, the developing motor 403 is in the on state (S362).
, and the toner supply mode is set (S36
4) If s, the period in which the toner replenishment mode is set (this period is determined in step 5334 when the toner 11 If
During the period when it is determined that the toner is light (C), toner replenishment is continued.

On the other hand, the developing motor 403 is in the on state (S362).
, and the toner supply mode is not set (S36
In case 4), toner replenishment is continued for a certain period of time until the low quantity replenishment timer exceeds (8366).

If the low constant replenishment timer is up at 8366, the process advances to 8368 and it is determined whether a copy operation is in progress.

If it is determined that the copy operation is in progress, and the above 836
In step 2, if it is determined that the developing motor has stopped due to the end of the copy operation due to the end of the auto-shut timer or the interruption of the copy operation by the clear stop key 93, the process advances to S370, and the strong 1bll toner is replenished. It is determined whether the request continuation mode is set, that is, whether the flag b is set.

If it is determined in step 5370 that the forced toner replenishment request continuation mode is not set, the process advances to step 5372, and if it is determined in step 8368 that the copying operation is not in progress (i.e., an unsteady drain). (If supply ends)
, and if there is a replenishment stop request in 5310, after turning off the developing motor in 8369, 53
The program proceeds to step 72, sets the output signal level from the output boat PA2 to a high level and turns off the replenishment request display LED 96, then proceeds to step 5374, lowers the flag b to cancel the strong control-ner replenishment request continuation mode, and then proceeds to step 8376. Proceed to the following. That is, the flag a is lowered to cancel the forced toner replenishment mode (5376), the output signal level from the output boat PAO is set to high level, toner is replenished, and the operation 33 is stopped overnight (S378), and the flag C is lowered to set the low constant output. To cancel the replenishment mode 3380>, set the flag d to cancel the toner replenishment mode 5382), and return to the main routine.

On the other hand, if it is determined in step 5370 that the forced toner replenishment request continuation mode is set (that is, if the copy operation that was previously executed during the non-regular toner replenishment operation has been completed), the process starts from 8376. 8376), set the output signal level from the output boat PAO to high level and stop the toner replenishment motor 33 (8378), and lower the flag C to cancel the forced toner replenishment request mode (8376). Please cancel supply mode (8380)
, lower the flag d to cancel the toner replenishment mode83
82), return to Main Luzin.

As described above, the operation of the device of this embodiment is 1III!
Ill be taken.

(Modification of Embodiment) In the embodiment described above, the toner concentration in the developer container 43 is detected by the magnetic sensor 11, and the amount of toner replenishment for the developer is determined. However, the present invention is not limited to this. For example, an electrostatic latent image for toner replenishment is formed on the surface of the photoreceptor using a reference chart or the like and developed, and the developed density is detected by a 7-photo sensor.
The amount of toner replenishment may be controlled according to this detected value. In this case, the photosensor is placed, for example, in the vicinity of the photosensitive drum 61 and between the separation charge cell 2 and the cleaning device 69.

Further, in the above embodiment, the toner tank 43 and the toner replenishing roller 44 located at the bottom of the toner tank 43 are used as toner replenishing means, but the present invention is not limited to such members; Any mechanism that can control the amount of toner may be used.

[Effects] In short, the present invention improves toner supply control in image forming apparatuses such as copying machines and laser printers.

As described in detail in the embodiments, in the present invention, when non-regular toner replenishment is commanded by the toner replenishment switch (input means), the control means adjusts the toner concentration based on the toner concentration detected by the toner concentration sensor. Toner is continuously supplied to the developing device until the detected toner density exceeds the set value. In other words, the amount of toner supplied is an appropriate amount corresponding to the insufficient amount.

Therefore, the density of the image reproduced on the paper becomes an appropriate density. That is, lightening of the reproduced image density due to a decrease in toner density is avoided.

Further, the above effect is achieved by one operation of the toner replenishment switch, so the operation is simple.

Further, in the present invention, during execution of the unsteady replenishment operation,
The image forming operation can be controlled by external input (external key manual signal, external III
If a command is issued (such as a command signal transferred from a computer), the non-regular replenishment operation is stopped and the image forming operation is executed with priority.

Therefore, regardless of the irregular replenishment operation, the image forming operation can be started at a desired time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the appearance of a copying machine according to an embodiment. FIG. 2 is an explanatory diagram of the main parts of the copying machine according to the embodiment. Third
The figure is an i, II I11 circuit diagram of a copying machine according to an embodiment. FIG. 4 is a flowchart showing an outline of copying machine control according to the embodiment. FIG. 5 is a flowchart showing the input processing of the flowchart of FIG. Figure 6 Part 1, Part 2,
and No. 3 are flowcharts showing the toner replenishment process of the flowchart of FIG. 4. 11... Toner II ff sensor 2... Control circuit 33... Toner supply motor 403... Developing motor 43... Toner tank 61... Photosensitive drum 91
... Toner supply switch 92 ... Print switch

Claims (1)

[Claims] (1) A developing device that visualizes an electrostatic latent image using toner, a toner concentration detection means that detects the toner concentration in a two-component developer in the developing device, and when the developing device is operated. a toner replenishing means for replenishing the developer with toner; an input means for instructing an unsteady replenishing operation different from the replenishing operation by the toner replenishing means; and when a replenishing operation is commanded by the input means. An image forming apparatus comprising: a control means for driving and controlling the toner replenishing means to continue the replenishment operation while the detected toner concentration is lower than a predetermined set value, the control means comprising: The image forming apparatus executes the image forming operation during the non-regular replenishing operation when an external input instructing the image forming operation is received during the non-regular replenishing operation.