JPH03161782A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent contamination in a machine body caused by the scattering of toner from occurring and to always output a copy having excellent image density in an initial time and through life by providing a varying means for varying a reference value in accordance with the use time of a developing device and the characteristic of developer. CONSTITUTION:The device is constituted of a detection means 48 for detecting the toner concentration of the developer, a control means 60 for controlling the replenishment of the toner T to the developing device 40 according to the compared result which is obtained by comparing an output from the detection means 48 with the reference value, and the varying means 62 for varying the reference value in accordance with the use time of the developing device 40 and the characteristic of the developer. In such a case, the reference value can be shifted with the characteristic of the life of the developer. Thus, the specific concentration of the toner in the developer is kept constant and the contamination in the machine body caused by the scattering of the toner is prevented from occurring, thereby always outputting the copy having the excellent image density in the initial time and through life.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is applicable to, for example, an image processing apparatus that is applied to an electronic copying machine equipped with a developing device that uses a two-component developer consisting of toner and carrier. The present invention relates to a forming device.

(Prior Art) Electronic copying machines have been put into practical use that detect the toner density in a developing device and control toner replenishment, thereby constantly providing copy output with stable image density. There is.

In this type of electronic copying machine, when controlling the specific toner density of a developing device that uses a two-component developer, for example, as shown in FIG. , and controls the toner replenishing device 103 according to the reading result. That is, as shown in FIG. 12, the output voltage of the toner sensor 10.1 is compared with a reference value, and when the output voltage exceeds the reference value, a replenishment start signal is sent to the toner replenishing device 103. When the output voltage becomes lower than a reference value, a stop signal is output.

In this way, conventionally, a certain reference value has been used to determine whether or not toner needs to be replenished.

However, in recent years, a plurality of developers have been prepared for one type of copying machine, for example, in response to monochrome printing or customer requests. However, depending on the type of developer, the amount of charge gradually decreases during use (during its life), resulting in poor fluidity, while in others it improves. Therefore, if you try to control the specific toner density using a fixed reference value, in the case of a developer whose charge amount gradually decreases, the toner density will increase with the life of the developer, resulting in an increase in toner consumption. This has the disadvantage that the inside of the machine gets dirty due to toner scattering, and defective images such as dust and fog appear on the copy output.

Conversely, in the case of a developer in which the amount of charge increases gradually, the toner density decreases with the life of the developer, resulting in a decrease in toner consumption and a decrease in the image density of the copy output. However, there was a drawback that defective images such as those caused by carrier development appeared.

(Problems to be Solved by the Invention) As mentioned above, in the past, the specific toner density was controlled using a fixed reference value, so in the case of a developer whose charge amount gradually decreases, There are drawbacks such as the occurrence of dirt inside the machine due to toner scattering, and defective images such as dust and fog appearing in the copy output.Also, in the case of a developer whose band Wi amount gradually increases, the copy output during the lifespan may be reduced. The disadvantages are that the image density of the image is lowered and defective images such as carrier development appear.

Therefore, the present invention can maintain a constant toner specific density in a developer containing toner, and maintains good image density at all times during the initial stage and throughout its life without causing stains inside the machine due to toner scattering. It is an object of the present invention to provide an image forming apparatus capable of obtaining copy output.

C Structure of the Invention (Means for Solving the Problems) In order to achieve the above object, the image forming apparatus of the present invention includes a developing device that uses a developer containing toner. a detection means for detecting the toner concentration of the developer; a control means for comparing the output from the detection means with a reference value; and controlling the replenishment of toner to the developing device according to the comparison result; and use of the developing device. and a variable means for varying the reference value according to time and characteristics of the developer.

(Function) According to the above-described means, the reference value for comparing the output from the detection means as the life progresses can be changed in accordance with the characteristics of the developer. First, it becomes possible to maintain stable toner consumption.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 7 shows an example of an electronic copying machine as an image forming apparatus of the present invention.

That is, a paper feed cassette 2 that can feed paper automatically or manually is mounted on the right side of the main body 1 of the copying machine. Further, a paper ejection tray 3 is attached to the left side of the copying machine main body 1. A document table 4 and an operation panel 5 are provided on the upper surface of the copying machine main body 1 and are capable of reciprocating in the direction of arrow a in the figure.

The operation panel 5 includes a display 6, a numeric keypad 7, an exposure setting volume 8, a print key 9, and the like.

FIG. 8 shows the internal structure of the copying machine main body 1. As shown in FIG.

Inside the copying machine main body 1, a drum-shaped photoreceptor 10 serving as an image carrier is provided approximately at the center thereof and is rotatably supported. The photoreceptor 10 can be rotated in the direction of arrow b in the drawing in synchronization with the document table 4 by a drive mechanism (not shown).

Thus, the photoreceptor 10 is uniformly charged by the charger 11. The original image produced by light irradiation from the exposure lamp 12 is formed into an image by the focusing light transmission body (trade name: self-occurring lens array) 13 that constitutes the optical system, so that an electrostatic latent image is formed on its surface. It is formed.

The latent image formed on the surface of the photoreceptor 10 is developed (turned into a toner image) by applying toner by a developing means (developing device) 30 disposed around the photoreceptor 10 in opposition to the latent image. This toner image is sent to the transfer charger 14 side by rotation of the photoreceptor 10.

On the other hand, the paper taken out from the paper cassette 2 (or
A manually fed sheet) P is sent to the transfer charger 14 side by a pair of registration rollers 16 in time with the toner image. When the paper P is brought into close contact with the photoreceptor 10, the toner image is transferred onto the paper P by the action of the transfer charger 14.

After the transfer, the paper P is peeled off from the photoreceptor 10 by a peeling charger 17 using AC corona discharge, and is conveyed on a conveyance path 18. Then, by passing through the fixing device 19. The toner image is fused and fixed onto the paper P. thus,
The paper P on which the image has been formed is ejected onto the paper ejection tray 3 by the paper ejection roller pair 20 as a copy output.

After forming the image, the toner remaining on the surface of the photoreceptor 10 is cleaned by a cleaning device 21, and the potential of the surface is lowered to a certain level or less by a static elimination lamp 22. It is considered to be in a state where it can be operated.

FIG. 9 shows the structure of the developing means 30.

The developing means 30 includes a developing device 40 that uses a two-component developer consisting of toner T and carrier, and a toner replenisher 50 that replenishes the toner T into the developing device 40.

That is, the developing device 40 includes upper and lower magnetic rollers 41 , 42 facing the opening on the photoreceptor 10 side, both large and small paddles 43 , 44 , a mixing auger 45 , a toner conveying auger 46 , and a scraper 47 . It is configured.

An automatic toner sensor (detection means) 48 of, for example, a magnetic permeability measurement type is disposed inside the developing device 40 to automatically detect the toner concentration within the developing device 40 .

The toner replenisher 50 includes a hopper 5 as shown in FIG.
1, a toner replenishment roller 52 provided at the lower part of the hopper 51, and a toner T on the toner replenishment roller 52 side.
and a toner mixer 53 that stirs the toner so as to convey and supply the toner.

Further, in the hopper 51, there is a toner empty mechanism 54 that detects when the remaining amount of toner T becomes less than a predetermined value.
is provided. This toner empty mechanism 54 is
a toner empty lever 55 that rotates according to the remaining amount of toner T; a toner empty actuator 56 that follows the toner empty lever 55; a permanent magnet 57 attached to the tip of the toner empty actuator 56; A reed switch 58 as a detector is provided outside the hopper 51 in a position corresponding to the permanent magnet 57.

Therefore, when the toner T is sufficiently stored in the hopper 51, the toner embodiment actuator 5
When the toner T enters between the permanent magnet 57 attached to the tip of the reed switch 6 and the reed switch 58, the reed switch 58 is turned off. Furthermore, when the amount of toner T in the hopper 51 decreases, the permanent magnet 57 and the reed switch 58 are brought into close contact with each other.
The reed switch 58 is turned on.

FIG. 1 shows the main parts of the control system of this electronic copying machine.

In FIG. 1, a CPU 60 serving as a control unit is in charge of controlling the entire copying machine. 61, a D/A converter 62 as variable means for D/A converting the reference input voltage to the auto toner sensor 48, and a counter circuit (counting means) 63 for counting the number of copies output. There is.

When the characteristic information of the developer used in the developing device 40 is entered manually from, for example, the numeric keypad (input means) 7 of the operation panel 5, the CPU 60 inputs the characteristic information to the counter circuit 63.
The auto toner sensor 4 detects the output of
The reference input voltage to 8 can be varied.

FIG. 2 shows the output characteristics of the auto toner sensor 48.

As is clear from this figure, toner specific concentration (wt%)
The output voltage of the auto toner sensor 48 is set to decrease when the toner replenishment determination value becomes higher, and when this output voltage becomes higher than the toner replenishment determination value as a reference value, the CPU 60 determines that the toner is in short supply. It looks like this.

Note that this auto toner sensor 48 has an initial sensitivity of 0,
6V/lwt%, and when the specific toner concentration in the developer is 4.0wt%, an output voltage of 2.Ov is generated.

FIG. 3 shows the relationship between the output voltage of the auto toner sensor 48 and the reference human power voltage for a developer having a toner specific concentration of 4.0% by weight.

That is, the auto toner sensor 48 receives 6.0 as the reference input voltage. When OV is set, the output voltage is 26 0
It is designed to output v. Also, for example 7. O
When a reference human voltage of V is set, the output voltage is 2.4V, and when a reference input voltage of 5.0V is set, the output voltage is 1
．． Each output voltage is 6V.

Next, with reference to FIG. 4, the operation of the above configuration will be explained.

For example, during a copying operation, when the specific concentration of toner in the developer is reduced, the output voltage of the sensor 48 is increased. Then, this output voltage is 2. When Ov (toner replenishment determination value) is exceeded, a toner replenishment start signal is supplied from the CPU 60 to the toner replenisher 50. This results in
As shown in area A, the developer ``54'' is supplied from the toner supply device 50.
0 is replenished with toner T.

Thereafter, when an increase in the specific concentration of toner in the developer is detected by the sensor 48 and the output voltage of the sensor 48 falls below the toner replenishment determination value, the CPU 60 supplies a toner replenishment stop signal to the toner replenisher 50, causing the toner to be removed. Replenishment of toner T by the replenisher 50 is stopped.

Then, when the copying operation continues, the toner is consumed again (area B), and the output of the sensor 48 becomes . begins to rise.

Usually, by repeating the above mode, the specific concentration of toner in the developer is maintained constant.

Note that when the replenishment toner T in the hopper 51 decreases,
This is detected by the toner empty mechanism 54.

Furthermore, if a copying operation is performed with the replenishment toner T in the hopper 51 running out, as shown in area C, the output voltage of the sensor 48 increases as the toner T in the developer decreases. In this case, in order to prevent carrier adhesion and developer leakage, when the output voltage exceeds 2.6V, a toner out mark is lit on the display 6 of the operation panel 5, and the copy operation is prohibited. Ru. This is because the forced replenishment operation is performed after the hopper 51 is replenished with the replenishment toner T (area D), and this forced replenishment operation causes the output voltage of the sensor 48 to fall below 2.3V, so that the replenishment operation is stopped. Temporarily stopped (forced replenishment mode canceled)
is restored to a state in which copy operations are possible.

The above is the control of the toner specific density when using an ideal developer in which the toner specific density does not change with life.

Next, a case will be described in which a developer is used which has the characteristic that the charge amount of the toner T changes depending on its life and its fluidity changes, so that the toner specific density changes between the initial stage and after the life.

Here, as shown in FIG. 5, the initial specific toner concentration is, for example, 4.0%, and the reference life is 40%.
,000 pieces, and after this life 6.0~7.
Developer T with the characteristic that the toner specific density is increased to 0wt%
An example will be described in which C1 and a developer TC2 whose characteristics are reduced to 2.0 to 3.0 wt % are used.

First, developer T whose toner specific density increases with life.
In the case of CI, for example, numeric keypad 7 is used for CPU 60.
A code (developer characteristic information) indicating the characteristics of the developer TCI is manually input. Then, during the copying operation, the number of copies output counted by the counter circuit 63 becomes C.
Read by PU60. Then, as the number of copies output increases, for example, every time 10,000 copies are counted,
A new reference input voltage is output from the CPU 60 to the D/A converter 62. This reference input voltage lowers the output voltage of the auto toner sensor 48 at a certain rate depending on the number of copies output.

That is, as shown by the solid line in FIG. 6, every time the number of copies output reaches 10,000, the reference human power voltage is lowered by -0.5V. The reference human power voltage is D/A converted by the D/A converter 62 and then supplied to the auto toner sensor 48 . Then, the output voltage of the auto toner sensor 48 is reduced by 0.2V every time 10,000 copies are output.

As mentioned above, until the number of copies output exceeds 10,000, the reference input voltage is set to 6. Ov and
The initial output voltage of the auto toner sensor 48 is set to 2. The copy operation is performed with the setting set to OV.

After this, if the number of copies output exceeds 10,000,
The reference human power voltage is 5.5V, and the auto toner sensor 48
The copy operation is performed with the output voltage set to 1.8V. In this case, the output voltage of the auto toner sensor 48 is lowered to 1.8V, but the on/off control of toner replenishment is strictly based on 2.0V (}ner replenishment determination value).

Therefore, even if the specific concentration of toner in the developer decreases due to the copying operation, the output voltage of the auto toner sensor 48 is 2.2. Toner replenishment operation is not performed until Ov is reached.

Therefore, the specific toner concentration in the developer is reduced, that is, it is possible to prevent the specific toner concentration from increasing and keep it constant.

On the other hand, in the case of the developer TC2 whose toner specific density decreases with life, conversely, as shown by the broken line in FIG. The reference input voltage increased by .5V is output.

As a result, the output voltage of the auto toner sensor 48 is increased to 1
It is increased by 0.2v every time 0,000 copies are output.

For example, when the number of copies output exceeds 10,000, and the reference input voltage is set to 6.5V, the output voltage of the auto toner sensor 48 is set to 2.2V. Then, the output voltage of the auto toner sensor 48 becomes 2.
The toner replenishment operation will continue until OV is reached. Therefore, the specific toner concentration in the developer is increased, that is, it is possible to prevent the specific toner concentration from decreasing and keep it constant.

As mentioned above, for developers whose toner specific density increases with life, the reference input voltage to the auto toner sensor is reduced according to the number of copies output, and for developers whose toner specific density decreases, In some cases, the reference input voltage to the sensor is increased in accordance with the number of copies output.

That is, the reference input voltage to the auto toner sensor can be changed depending on the life characteristics of the developer.

Thereby, the level of the output voltage of the sensor, that is, the toner replenishment determination value, can be changed as the life progresses. Therefore, it is possible to use a developer of any characteristic with a stable and constant toner specific concentration until the end of its life.

In addition, in the above embodiment, an electronic copying machine was explained as an example, but
The invention is not limited to this, and can be applied to various image forming apparatuses including a developing device that uses a developer containing toner, such as a laser beam printer.

It goes without saying that various other modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As detailed above, according to the present invention, the reference value can be shifted in accordance with the life characteristics of the developer, so that the specific toner concentration in the developer can be kept constant. It is possible to provide an image forming device that can always obtain copy output with good image density both initially and throughout its life without causing stains inside the device due to toner scattering.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a control system showing an embodiment of the present invention, FIG. 2 is a diagram showing the output characteristics of an auto toner sensor, and FIG. 3 is a diagram showing the output characteristics of an auto toner sensor. FIG. 4 is a diagram showing the relationship between the output voltage of the auto toner sensor and the reference human power voltage for Owt% developer, and FIG. 4 is a diagram shown to explain the toner replenishment operation.
Fig. 5 is a diagram shown to explain the life characteristics of the developer, Fig. 6 is a diagram shown to explain the toner replenishment operation according to the characteristics of the developer, and Fig. 7 is an external perspective view of the electronic copying machine. , FIG. 8 is a side view schematically showing the internal structure, FIG. 9 is a block diagram schematically showing the developing device, FIG. 10 is a block diagram schematically showing the toner supply device, and FIG. 11 is a block diagram schematically showing the toner supply device. 12 shows the prior art and its problems. FIG. 11 is a block diagram showing the main parts of the control system, and FIG. 12 is a diagram for explaining the toner replenishment operation. DESCRIPTION OF SYMBOLS 1... Copying machine body (image forming device), 30... Developing means (developing device), 40... Developing device, 48... Auto toner sensor (detecting means), 50... Toner replenisher , 60...CPU (control means) 62...D/A converter (variable means) 63...Counter circuit.

Claims (2)

[Claims] (1) In an image forming apparatus equipped with a developing device that uses a developer containing toner, a detection means for detecting the toner concentration of the developer, and an output from this detection means is compared with a reference value, and the comparison result is The present invention is characterized by comprising: a control means for controlling the supply of toner to the developing device according to the above, and a variable means for varying the reference value according to the operating time of the developing device and the characteristics of the developer. Image forming device. (2) In an image forming apparatus equipped with a developing device that uses a developer containing toner, a detection means for detecting the toner concentration of the developer, and an output from this detection means is compared with a reference value, and the comparison result is a control means for controlling the replenishment of toner to the developing device according to the above; an input means for inputting the characteristics of the developer used in the developing device; a counting means for counting the number of times of development by the developing device; By inputting the characteristics of the developer using the input means,
An image forming apparatus comprising: variable means for varying the reference value according to the counting result of the counting means.