JPH052338A - Toner concentration control method for developing device - Google Patents

Abstract

PURPOSE:To complete setting in a short time by setting a reference value by considering a stable value in advance in the case of setting the reference value at the time of initially using a developer in an inductance ATR (controller). CONSTITUTION:In a developing device provided with a toner concentration controller which replenishes toner by comparing an output value in accordance with the toner concentration of developer obtained by mixing carrier and toner with the reference value previously set, a value obtained by subtracting 0.5V from the output value outputted one minute after stirring is set as the reference value. Namely, the setting is not performed after performing stirring for about twenty minutes, and the setting is completed for one minute. Thus, the stirring is performed with other sequence after completing the setting. That means, as to an inductance ATR head 19, analog output obtained by detecting developer concentration is converted to digital output by an A/D converter 20, and the toner replenishing screw 23 of a hopper for replenishing the toner is rotated so as to replenish the toner for the time corresponding to the difference between the signal value and the reference value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner density control method for a developing device for forming a latent image on an image bearing member and visualizing the latent image with toner.

[0002]

2. Description of the Related Art Conventionally, as a recording system for forming a full-color image, an electrophotographic system, an inkjet recording system, a thermal transfer recording system and the like are known.

Among these, the electrophotographic system is capable of high speed and can be used for plain paper, and in recent years, product development has been further advanced.

In forming a full-color image of the electrophotographic system, many developing devices use a two-component developer having a toner and a carrier from the viewpoint of the tint of the image. In this case, the developing device is used for image formation. When the toner inside is consumed, it is necessary to replenish the developing device with toner corresponding to the consumption. Therefore, the toner concentration is detected and toner concentration control is performed, that is, the developer concentration detecting device and the control device (hereinafter, The toner density is kept constant by ATR).

FIG. 2 is a side view showing an example of a conventional developing means.

In FIG. 2, 3 is a developing sleeve and 4 is an image carrier.

The inside of the developing device 9 arranged facing the image carrier 4 is divided into a developing chamber 11 having a stirring screw 16 and a stirring screw 17 by a partition wall 10 extending in the direction perpendicular to the plane of FIG. And a stirring chamber 12 having

The upper portion of the partition wall 10 is open, and the developing chamber 1
The excess developer in 1 is collected in the screw section on the stirring chamber side and circulated.

The developing chamber 11 and the agitating chamber 12 contain a two-component developer containing toner and a carrier, and replenishment toner signals the change in the output value of the inductance ATR head 19 from the conveying upstream side of the agitating chamber screw. The toner is converted into a value, and toner corresponding to the difference from the reference value is replenished.

Further, the partition wall 10 is formed with an opening at the front and rear ends in the figure for communicating the developing chamber 11 and the stirring chamber 12 with each other.

The developing chamber 11 of the developing device 9 has an opening at a position corresponding to the developing area facing the image carrier 4, and the developing sleeve 3 is rotatable so as to be partially exposed in the opening 14. It is provided.

The developing sleeve 3 is made of a non-magnetic material, rotates in the direction of the arrow in the drawing during the developing operation, and has a magnet 13 as a magnetic field generating means fixed therein. Further, when the developing sleeve 3 is developed to visualize the latent image on the image carrier 4, AC and DC biases are applied by the power supply 15, and the toner adheres to the image carrier 4 from the developing sleeve 3.

As described above, in the conventional developing means shown in FIG. 2, the inductance ATR head 19 detects the apparent magnetic permeability due to the change of the mixing ratio of the magnetic carrier and the non-magnetic toner, and converts it into an electric signal. , The apparent permeability changes according to the change of the toner amount in the developer composed of the mixture of toner and carrier, and the output is shown in FIG. 3, and when the output is increased from the reference density, The toner is replenished so as to return to the above.

[0014]

However, in the conventional example shown in FIG. 2, when the initial developer is charged and the reference value is set, stirring is performed for a long time in order to stabilize the charge and the like of the toner. There was a problem that the reference value had to be set later.

The present invention is intended to solve the above problems. That is, an object of the present invention is to provide a toner density control method for a developing device, which can finish setting a reference value in a short time.

[0016]

In order to achieve the above object, the toner concentration control method for a developing device according to the present invention is preset with an output value according to the toner concentration of a developer in which a carrier and toner are mixed. In a developing device having a toner density control device that replenishes toner by comparison with a reference value, the reference value is set at a predetermined timing based on the relationship between the stirring time of the developer and the output value.

[0017]

According to the present invention, when setting the reference value of the inductance ATR, the reference value is set at a predetermined timing in consideration of the stable value from the relationship between the stirring time and the output value prepared in advance. Ends.

[0018]

【Example】

(First Embodiment) FIG. 1 is a side view showing an example of developing means for carrying out the first embodiment of the present invention.

In FIG. 1, 3 and 4 and 9 to 1
Reference numerals 7 and 19 are similar to the members described in FIG.

20 is an A / D converter, 21 is a CP
U and 22 are reference values, and 23 is a toner supply screw.

That is, the inductance ATR head 1
9. First, the analog output that detected the developer concentration is A /
The D converter 20 converts the signal into a digital output, and the toner replenishing screw 23 of the toner replenishing hopper rotates for a time corresponding to the difference between the signal value and the reference value to replenish the toner.

Next, the flow of the first embodiment of the present invention will be described with reference to FIGS. 4 and 5.

FIG. 4 shows changes in the agitation time and output value by the agitating screws 16 and 17 after the initial developer is charged at an absolute humidity of 60%. Although showing a change until reaching a stable value, when the polyester toner in which the pigment having a diameter of about 10 μm used in this example is dispersed and the ferrite type spherical carrier having a diameter of about 50 μm are combined, the initial agent is added. An output value of 2.70V at that time is 2.50V after 1 minute and 2.0 after about 20 minutes.
It becomes 0V and is set as a reference value.

Therefore, according to the present embodiment, the value obtained by subtracting 0.5 V from the output value after 1 minute of stirring is set as the reference value, so that the value is not set after stirring for about 20 minutes, but in 1 minute. The setting is completed, and after the completion, stirring is performed together with other sequences.

According to the flow shown in FIG. 5, first, the initial developer is added in step S101, and then step S10.
The agitation by the agitation screws 16 and 17 is started at 2, and after 1 minute has elapsed at step S103, the output value A at that time is detected. Therefore, (output value A-0.5) V
The reference setting is completed by setting as the reference value.

As described above, the inductance AT
When setting the reference value at the time of adding the initial developer in R, by setting the reference value in consideration of the stable value in advance, the setting can be completed in a short time.

Next, some embodiments of the present invention will be described.

(Second Embodiment) In the present embodiment, the set value is shifted with the stirring time from the start of stirring until the stabilization time is reached. Specifically, FIG.
Referring to, by setting the set value that was 2.70V at the start to 2.50V after 1 minute,
Even until it reaches a stable value, under the proper setting value,
A copy operation can be performed.

(Third Embodiment) In this embodiment, the above-mentioned first embodiment is used.
The time is effective and shortened by effectively combining the sequences after the setting of the reference value according to the embodiment. First, in the first embodiment,
At the time of setting the reference value after 1 minute of stirring, since the heat roller used for the fixing means is not warmed up yet, the warm up of the heat roller is performed in parallel, and
By continuing the stirring of the developing device until the first copy is made, the same amount of stirring as the conventional one is given to the developer by the start of copying, and if the purpose can be achieved, other sequences can be used. You may combine.

(Fourth Embodiment) Since the electric charge of the toner of the developer is very easily affected by humidity, and the humidity also has a great influence on the developer due to other factors, The output value of the inductance ATR used in the invention also changes considerably depending on the humidity.

Specifically, when the humidity is high and the absolute humidity is 80%, the output value stability range due to stirring is 0.
It is 4V, and at low humidity 20% absolute humidity, 0.7
It was V.

Therefore, in the present embodiment, the humidity and / or temperature sensor detects the environmental condition in the vicinity of the developer, and the offset amount to reach the stable output value is determined based on the detected environmental condition. By having the offset determination table according to the conditions, the CPU can calculate an appropriate set value.

[0033]

As described above, according to the present invention,
In a developing device having a toner concentration control device that replenishes toner by comparing an output value according to the toner concentration of a developer in which a carrier and toner are mixed with a preset reference value, when the initial developer is fed into the inductance ATR, When setting the reference value, by setting the reference value in consideration of a stable value in advance, there is an effect that the setting can be completed in a short time.

[Brief description of drawings]

FIG. 1 is a side view showing an example of developing means for carrying out a first embodiment of the present invention.

FIG. 2 is a side view showing an example of a conventional technique.

FIG. 3 is an explanatory diagram showing a relationship between toner concentration and an inductance ATR output value.

FIG. 4 is an explanatory diagram showing the relationship between the stirring time and the output value when the initial developer is added.

FIG. 5 is an explanatory diagram showing a basic operation of the developing unit in FIG.

FIG. 6 is an explanatory diagram showing the relationship between absolute humidity and offset.

[Explanation of symbols]

3: developing sleeve 4: image carrier 9: developing device 11: developing chamber 12: stirring chamber 19: inductance ATR head 20: A / D converter 21: CPU 22: reference value 23: toner supply screw

Claims (1)

Claim: What is claimed is: 1. A developing device having a toner concentration control device for replenishing toner by comparing an output value corresponding to a toner concentration of a developer obtained by mixing a carrier and toner with a preset reference value. In the toner density control method for a developing device, the reference value is set at a predetermined timing based on the relationship between the stirring time of the developer and the output value.