JPH0695249B2 - Toner replenishment method in image forming apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toner replenishing method in an image forming apparatus, and more specifically, it is applied to an electrophotographic copying machine having a toner bottle exchange type developing device using a dry two-component developer. The present invention relates to a method of replenishing toner in an image forming apparatus.

(Prior Art) Conventionally, as an image forming apparatus, a uniformly charged photoconductor is irradiated with an optical image to be supplied for image formation, and exposed, and an electrostatic force is applied to an electrostatic latent image carried in this manner. A method is known in which a toner is made to adhere and the toner image is fixed to obtain a recorded image, or a method in which the toner image is further transferred to a recording paper to obtain a recorded image.

For example, in an electrophotographic copying machine, even if the sensor that detects the degree of toner adhesion on the photoconductor detects that the degree of toner adhesion on the photoconductor does not meet the standard, it is considered for the convenience of the user. Then, without immediately stopping the operation of the copying machine, the toner replenishment display is first blinked to warn the user of that fact, and a certain number of copies can be continued thereafter.

Therefore, for the time being, the copying is continued until the machine is stopped, and after that, the toner replenishment and filling work such as the replacement of the toner bottle is performed to prepare for the next copying.

Immediately after the toner bottle is replaced, the state where the toner replenishment rate into the developing container (rotation time of the toner replenishing roller per one sheet of paper) is maximized (the state when the machine stops due to insufficient toner) is maintained. Therefore, the agitation is insufficient due to the rapid replenishment of the toner, and the toner is used for the development in a state in which the rise of the charge amount related to the binding force between the toner and the carrier is low.

Therefore, there is a problem that the background is stained or the toner is scattered to stain the surroundings.

(Object) Accordingly, it is an object of the present invention to provide an improved toner replenishment method capable of solving the problems of background stains and scattering associated with the rapid replenishment and replenishment of toner after replenishment. .

(Structure) In order to achieve the above object, the present invention automatically sets the toner replenishment rate to the toner replenishment rate in accordance with the toner capacity exchange when the sensor output detects the toner shortage at the time of image formation immediately after the toner container exchange. The feature is that the toner supply rate is once lowered to the minimum, and then the toner supply rate is gradually increased.

Hereinafter, a specific description will be given based on an embodiment of the present invention.

As a replaceable developing container, there is a container called a toner cartridge or a toner bottle.

In FIG. 3 illustrating an example of a developing device having a toner bottle, reference numeral 1 is a drum-shaped photosensitive member, reference numeral 2 is a developing sleeve having a fixed magnet inside and rotating in the arrow direction, and reference numeral 3 is a stirring and conveying function. The paddle wheel has a reference numeral 4, a toner replenishing roller having a notch on its periphery, a reference numeral 5 is a stirring spring, and a reference numeral 6 is a toner bottle. Details of these members are well known and will not be described.

Next, the toner supply system will be described.

A reference pattern 13 having a predetermined reflectance is attached to the lower surface of the contact glass 12. The optical image of the reference pattern 13 is set so as to be imaged on a portion of the photoconductor 1 outside the image forming area of the original image via an image forming optical system, a mirror and the like.

Further, in the direction of rotation of the photosensitive member 1, behind the arrangement portion of the developing sleeve 2 and at a portion where the image forming region of the reference pattern 13 passes, a pair of sensors 14 including a issuing portion and a light receiving portion is provided.
Is provided. This sensor 14 has a reference pattern 13
The light reflected from the toner image (hereinafter referred to as sensor detection pattern) that visualizes the electrostatic latent image of is detected and photoelectrically converted,
Outputs sensor output V _SP .

After the reference pattern 13 passes, the reflected light from the exposed portion of the photosensitive member, that is, the portion where toner is not originally attached is detected and photoelectrically converted, and the sensor output V _SG is output. The detection signals from these sensors 14 are determined by the central processing unit CPU, and signals are sent to the drive unit 15 based on the result,
The toner supply roller 4 and the stirring spring 5 are driven. In addition, the central processing unit CPU allows the toner hopper 8
When it is determined that the toner inside has been consumed, the display indicating that the toner has ended is lit on the display unit 16 to prompt the operator to convert the toner bottle 6.

Here, two kinds of values, K ₁ and K ₂ , are set as the predetermined control reference that is data provided in advance in the central processing unit CPU and should be compared with the output V _{SP of the} sensor 14. For example,
The control reference K ₁ is the normal image density (ID = 1.
3) Upper limit of sensor output (0.5V) required to obtain more than
However, when V _SG = 4.0V) is set as a guide. Therefore, while the sensor output V _SP is below the control reference K _1, it means that the sensor detection pattern has sufficient toner adhesion. In this case, it is considered that a sufficient amount of developer has been secured in the developing container 11, and the toner replenishing operation by the toner replenishing roller 4 and the replacement of the toner bottle are not necessary.

Further, the control reference K ₂ is the upper limit of the sensor output (0.9V where V _SG = 4.0V) required to obtain the minimum required image density (ID = 1.0) as a proper image in FIG. It is set as a guide. Therefore, while the sensor output V _SP is below the control standard K ₂ , the image density in the sensor detection pattern is maintained, so it is determined that toner is present in the toner bottle, but the control standard K ₂ is set. When it exceeds, it means that there is no toner in the toner bottle on condition that the toner supply rate is maximum.

Here, the toner replenishment rate is a value that increases or decreases in proportion to the amount of rotation of the toner replenishing roller 4 that replenishes toner into the developing container 11 from the toner hopper or toner bottle, and is a toner replenishment rate of at least two stages or more. Allows switching. When the toner supply roller 4 is driven at a low speed, the toner supply rate is low, and when it is driven at a high speed, the toner supply rate is high. For example, the toner replenishment rate is 20% for black solid area, 40%
%, 60%, and initially set to a toner replenishment rate corresponding to a black solid portion area rate of 20% (hereinafter referred to as toner replenishment rate 20% for convenience, hereinafter the same).

Next, the toner replenishment control process will be described with reference to FIG.

After the main switch of the image forming apparatus is turned on, the toner replenishment control by the sensor 14 is executed once every 10 exposures. That is, in process P ₁ , the main switch of the image recording apparatus is turned on, and
The value of 10n + 1 is compared, and if these values match, a toner image of a reference pattern is formed on the photoconductor in process P ₂ , and the image density detection function of the sensor operates. Here, n is a natural number and means the number of times the sensor 14 detects the reflected light from the sensor detection pattern after the main switch is turned on. Therefore, when the main switch is turned on and one copy is made, since n = 0, 10n + 1 =
Since it is 1, which is equal to 1 of the number of copies, it is judged as YES in process P ₁ and the process proceeds to process P ₂ . After that, since n = 1 has already been counted, 10n + 1 = 11, so the sensor 14 does not function until the number of copies reaches 11, and the same toner supply state as the previous time is continued in process P _3. . Thereafter, according to the same concept, the toner density control is executed by the function of the sensor 14 once for every 10 copies.

Now, when the sensor detection pattern is created in process P ₂ , then in process P _{4, the} sensor output V _SP , V
Each _SG is detected. First, sensor output in process P ₅
The value of V _SG is compared to a reference voltage, eg 2.5V. For example, the sensor output V _SG is set to be about 4.0 V in the initial state where the sensor 14 is not contaminated with toner, so the sensor output V _SG is large when the sensor output V _SG is less than 2.5 V. When it is determined that the sensor output does not rise, the toner supply is stopped in process P ₆ , and an appropriate display is performed to remove the dirt on the sensor 14.

On the other hand, when the sensor output V _SG exceeds 2.5 V, there is no dirt on the sensor 14, so in the next process P ₇ , the sensor output
The magnitude relationship between V _SP and the control standards K ₁ and K ₂ is determined.

In process P ₇ , the sensor output V _SP is the control criterion K
₁ (= 0.5V) when less than need not supply the toner from a translation of the high density image is obtained, the process P ₈
Then, the processing is performed with the content that toner supply is not performed.

Further, in the same process P ₇ , if the sensor output V _SP exceeds the control reference K ₁ (= 0.5V) and does not reach the control reference K ₂ (= 0.9V), a toner that can obtain an image of an appropriate density can be obtained. It is determined that the density is reached, and in process P ₉ , the toner replenishment is repeated 10 times at the toner replenishment rate corresponding to the black solid area ratio 20% according to the initial setting.

Alternatively, in the same process P ₇ , when the sensor output V _SP exceeds the control reference K ₂ (= 0.9 V), it is determined that the toner density is lower than that at which an image with an appropriate density can be obtained. , In process P ₁₀ , it is checked whether the toner supply rate is maximum, and if it is not maximum,
In process P ₁₁ , the toner replenishment rate was raised to the maximum of 60%,
In the process P ₁₂ , the toner replenishment is executed at the toner replenishment rate after being raised to the maximum. And again process P ₁
When the process is repeated and it is determined that K ₁ <V _SP <K ₂ in the process P ₇ , the level is lowered to the initial setting value, that is, the toner replenishment rate corresponding to the black solid area ratio of 20%.

By the way, if it is determined in the process P ₁₀ that the toner replenishment rate is the maximum, the image density has not reached the appropriate level even though the toner replenishment rate is the maximum. There is no toner in the hopper. Therefore, it performs toner result is displayed in process P _13, so that the prompt as taking processing apparatus according to the replenishment of toner to the operator.

In this state, ID = 1.0 to 1.1, and the lamp that notifies the end of toner blinks. However, since it is inconvenient if the machine stops during copying, the machine is not stopped, and a fixed number of sheets, for example, about 50 sheets are copied and then stopped. However, just before this stop,
Although it depends on the manuscript, the image is even lighter with ID = 1.0 or less.

To replace the toner bottle, open the door cover. When the toner bottle is replaced with a new one and the door cover is closed, the toner end display state is reset and copying can be performed again.

Then, when the copying is started, the processing is executed from the start of FIG. 1, and the processes P ₁₄ , P ₁₅ , P ₁₆ , P ₁₇ , P ₁₈ , P ₁₉ are the processes P ₁ , P ₂ , P ₃ ,, P ₄ , P ₅ , P ₆
According to the process P ₂₀ , the sensor output V _SP is the control reference K
_If it is judged that it is smaller than ₂ (= 0.9V), process P ₁
Return to.

In process P ₂₀ , the sensor output V _SP is the control reference K ₂ (= 0.
9V) larger as when it is determined, when the process P ₂₁ of the first after the replacement toner bottles copies (m = 1. However,
m is the number of times of detection after toner bottle replacement), the toner replenishment rate is set to the minimum, for example, 20%, and the toner is replenished, and the process returns to the process P ₁₄ . The above processing is performed by processes P ₂₂ , P
It shows in the flow of ₂₃ .

When it is determined that it is not the first time (m ≠ 1) in process P ₂₁ , it is determined in process P ₂₄ whether or not the maximum replenishment rate is reached.
_{In 25} , the toner replenishment rate is raised by one step, and in process P ₂₆ , the toner is replenished by the raised replenishment rate in process P ₁₄
Return to.

In the above description, if the maximum replenishment rate has already been reached in process P ₂₄ , the image density does not appear despite the maximum replenishment rate, so the toner end display is given in process P ₂₇ .

The above example starts replenishment from the minimum replenishment rate of 20% until the sensor output V _SP becomes smaller than the control reference K ₂ (= 0.9 V).
It is a method of gradually increasing to 40% and 60%.

By doing so, the replenishment rate of the toner gradually increases, so that the problems of background stain and toner scattering due to insufficient stirring are solved.

Further, in addition to the above example, the following examples are possible. After the toner bottle is replaced and the toner end display state is reset, the value is the control reference in process P ₂₀ until the sensor output V _SP is detected any number of times, for example, up to 5 times.
Even if it is determined that it is higher than K ₂ (= 0.9V), the toner is replenished at the default toner replenishment rate of 20%, and thereafter, the toner replenishment rate is gradually increased according to the above example.

Further, in carrying out each of the above examples, it is possible to reduce the copy speed and prolong the stirring time. Even in this case, it goes without saying that if the sensor output V _SP falls below the control reference K ₂ (= 0.9 V), the normal copy speed is restored.

As another method of controlling the toner replenishment amount by detecting the degree of toner adhesion to the toner image with a sensor, there is also a method of detecting the permeability, bulk density, color tone change, etc. of the developer with a sensor. It is also possible to implement these methods.

(Effect) According to the present invention, the toner is sufficiently stirred and is used for development in a state where the charge amount is increased to a required level, so that problems such as background stain and toner scattering are solved,
It is convenient.

[Brief description of drawings]

1 and 2 are flowcharts for explaining an embodiment of the present invention, FIG. 3 is a view for explaining an example of a developing device suitable for carrying out the present invention, and FIG. 4 is a relationship between sensor output and image density. FIG. 6 ... Toner bottle, 14 ... Sensor.

Claims (1)

[Claims] 1. A sensor detects the degree of toner adhesion of a toner image obtained by forming a light image of a reference pattern having a predetermined reflectance on a uniformly charged photoconductor, and in accordance with the sensor output. In the toner replenishment method for controlling the toner replenishment rate to the developing device, when the sensor output detects the toner shortage at the time of image formation immediately after the toner container replacement, the toner replenishment rate is automatically set once in accordance with the toner container replacement. A method for replenishing toner in an image forming apparatus, comprising: dropping to a minimum replenishment level, and thereafter gradually increasing a toner replenishment rate.