JPH01161381A - Developing device - Google Patents

Abstract

PURPOSE:To accurately execute the measurement of toner concentration based upon a magnetic permeability change detecting system by arranging a flow rate regulating means for regulating the quantity of a developer flowing into the surface of a sensor on the upstream side of the sensor to stabilize the flow rate. CONSTITUTION:In the developing device provided with the sensor 23 for controlling toner concentration based upon the magnetic permeability change detecting system, the flow rate regulating means 19 for regulating the quantity of the developer flowing into the surface of the sensor 23 is arranged on the upstream side of the sensor 23. Namely, a part of the developer flowing into the rear part of the means 19 through a gap S of the means 19 is passed through an opening 21 of a partition plate 20, descended along an inclined plate 22 continued from the opening 21, guided to the upper part of the 2nd agitating member 17, agitated by the member 17, and then sent to the lower part of the 1st agitating member 16. Consequently, the flow rate to the surface of the sensor is quantified and a shaped flow is formed, so that packing density is stabilized and measurement based upon the toner concentration sensor can be accurately executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a developing device that develops an electrostatic latent image formed on a photoreceptor drum into a toner image.

[Background of the Invention] □ Generally, in a two-component developer used in this type of developing device, the amount of toner mixed into a constant weight of carrier (iron content) is about 4% by weight. Unlike carrier, this toner decreases with each copy, so when toner decreases, carrier increases relatively. Therefore,
Measure the magnetic permeability at the standard mixture ratio of carrier and toner, then measure the magnetic permeability of the developer circulating in the developing device.If the voltage is higher than the standard value, the toner concentration is low, and if the voltage is low, Since it is known that the toner concentration is high, it is possible to constantly monitor the toner concentration by installing a toner concentration sensor that detects changes in this voltage.

However, when installing such a toner density sensor, it is important to note that the developer that adheres to the developing sleeve and is carried to the front of the photoreceptor drum and is used for development has a reduced toner content (tired developer). Of course, it is necessary to ensure that the still fresh developer (active developer) flows onto the sensor surface in a well-stirred and mixed state (that is, the exhausted developer and active developer are not biased to one side). The purpose of this method is to quantitatively stabilize the flow rate of the developer, and if this is unstable, accurate measurement may not be possible and there is a risk that an erroneous signal may be output.

[Purpose of the invention]

In view of the above points, it is an object of the present invention to provide a developing device that can accurately measure toner concentration using a magnetic permeability change detection method.

[Structure of the invention]

In order to achieve the above object, the present invention provides a developing device equipped with a sensor that controls toner concentration using a magnetic permeability change detection method, and includes a flow rate regulating means for regulating the amount of developer flowing toward the sensor surface on the upstream side of the sensor. The structure is such that the flow rate can be stabilized.

〔Example〕

Next, the present invention will be explained based on the embodiments shown in FIGS. 1 to 3.

In FIG. 1, reference numeral 10 denotes an image forming unit of a copying machine, and inside the image forming unit 10 there is a photoreceptor drum 1), a charging section 12, a developing section I3, and a cleaning section 1.
4 is placed. Note that the transfer section is provided so as to correspond to the lower surface of the photoreceptor drum 1), and is not provided in this unit 10.

The developing section 13 includes a developing sleeve 15, a first stirring member 16 for main stirring, and a second stirring member 17 for auxiliary stirring. The developing sleeve 15 is disposed close to the photoreceptor drum 1) and electrostatically adsorbs the developer onto the drum surface. It functions to develop the WI image as a toner image.

The first stirring member 16 has a stirring plate 16b fixed obliquely to the rotating shaft 16a (not shown in the drawing), and a cross-shaped flat plate 16c is provided between each stirring plate, so that the first stirring member 16 can rotate in the direction of the arrow. It looks like this. Therefore, it adheres to the developing sleeve 15 and is carried to the front surface of the photoreceptor drum ti.
The exhausted developer from the sleeve side, where the toner content has been reduced due to development, and the still fresh active developer can be stirred and mixed while being scraped up in the rotational direction (from bottom to top).

A part of the developer scraped up by the first stirring member 16 passes through the gap G of the doctor means 18 and adheres to the surface of the developing sleeve 15, as shown in the enlarged view of FIG. The first stirring member 1 passes through the gap S of the regulating means 19.
Sent to the rear of 6.

The regulating means 19 is provided here so that the fresh active developer fed from the second stirring member 17 side to the lower part of the first stirring member 16 rides on the first stirring member 1G and moves backward. Fill L is to mix well with the exhausted developer coming from the sleeve side so that it can be sent to the rear. Since the regulating means 19 is installed near the doctor means 18, it is fixed to the upper plate 10a of the image forming unit 10 integrally with the doctor means 18. That is, the gap G of the doctor means 1B
and the gap S of the regulating means 19 can be adjusted with one touch.

A part of the developer that has passed through the gap S of the regulating means 19 and gone around to the rear passes through the opening 21 of the partition plate 20 as shown by arrow A in FIG. The liquid flows downward along the radial axis, and is sent to the upper part of the second stirring member 17, where it is agitated once and sent to the lower part of the first stirring member 16.

Further, a part of the developer that has been deposited in the opening 21 of the temporary partition 20 descends along the partition plate 20 as shown by arrow B, and is sent to the lower part of the first stirring member 16, where it is It merges with the developer that has advanced as indicated by the arrow A.

A toner concentration sensor 23 is provided in the partition plate 20 facing the flow path of the developer flowing through the opening 21 as shown by the arrow A and uses a magnetic permeability change detection method. The sensor 23
Detects the magnetic permeability of the developer, compares the detected value with a reference voltage value stored in advance, and outputs a drive signal or a stop signal to the drive means of the toner supply roller 31. That is,
When the detected value is high, the toner concentration is low, so toner replenishment is commanded, and when the detected value is low, the toner replenishment is stopped. The reason why the toner concentration sensor 23 is provided here is because the flow rate of the developer, which is the object to be detected, is on the upstream side.
This is because the means (in this embodiment, the opening 21 provided in the temporary partition 20) is provided to quantitatively stabilize the flow rate of the developer flowing in front of the sensor. Furthermore, this sensor is installed between the first stirring member 16 and the second stirring member 17, so that it can be used in a place where the fatigued developer and active developer are not biased to one side and are well mixed. be.

24 is a toner cartridge, 25 is a toner retention chamber in which the toner cartridge 24 is replaceable, and 26 is a supply chamber that communicates with the toner retention chamber 25 through an upper window 27.

Toner retained in the toner retention chamber 25 is scooped up into the replenishment chamber 26 by the operation of the ladder chain 28 and supplied through the upper window 27. As shown in the third figure, in the lower part of the replenishment chamber 26, an opening groove 29 and a replenishment roller 31 which are in sliding contact with the end member 30 of the opening groove 29 are installed along the development width direction. When the replenishment roller 31 rotates in the direction of the arrow in response to a command from the sensor 23, the developer in the replenishment chamber is caught on the lower surface of the roller and falls while pushing the mouth end member 30 open. This falling point is located at the opening 21 of the partition plate 20.
The developer is mixed on the developer flowing from the first stirring member 16 to the upper surface of the second stirring member 17.

Then, it is auxiliary stirred by the second stirring member 17 and sent to the lower part of the first stirring member 16.

Incidentally, if the replenishment toner were directly carried to the front of the toner concentration sensor 23 together with the developer flowing down on the inclined plate 22, the toner concentration would become high, making it impossible to accurately measure the concentration. For this reason, it is necessary to cover the portion of the opening groove 29 of the toner replenishment chamber corresponding to the installation portion of the sensor with a suitable shielding member to limit the supply of toner to the front surface of the sensor.

〔Effect of the invention〕

As described above, the present invention provides a developing device equipped with a sensor that controls toner concentration using a magnetic permeability change detection method.
The feature is that a flow rate regulating means for regulating the amount of developer flowing into the sensor surface is provided on the upstream side of the sensor, so that the flow rate to the sensor surface is quantified, and the backing density is reduced because a clean flow is created. An excellent effect can be achieved if the toner concentration sensor can perform measurements stably and accurately.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is an enlarged sectional view of an image forming unit incorporating the developing device of the present invention, Fig. 2 is an explanatory view showing the relationship between the developing sleeve and the first stirring member, and Fig. 3 is an explanatory view showing the relationship between the developing sleeve and the first stirring member. The figure is an explanatory diagram showing the operation of the embodiment. 10...Image forming unit 1) -Photosensitive drum 13...-Developing section 15...Developing sleeve 16...First stirring member 17--Second stirring member 20...Partition Plate 21 - Opening (developer flow rate regulating means) 22 - Inclined plate 23 - Toner concentration sensor

Claims (2)

[Claims] (1) A developing device equipped with a sensor that controls toner concentration using a magnetic permeability change detection method, characterized in that a flow rate regulating means for regulating the amount of developer flowing toward the sensor surface is provided upstream of the sensor. Developing device. (2) Claim 1, wherein the flow rate regulating means is an opening provided in a partition plate between a flow path going around from the top surface to the rear surface of the first stirring member and a flow path communicating with the top surface of the second stirring member. The developing device described.