JPH01161382A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a developer from being measured by a sensor immediately after toner feeding and to obtain the accuracy of measurement by providing the title device with a means for restricting the feeding quantity of toner to a sensor part as compared with that to other parts. CONSTITUTION:The developing device provided with the sensor 23 for controlling toner concentration based upon a magnetic permeability change detecting system is also provided with the means for regulating the feeding quantity of toner to the sensor part 23 as compared with that to other parts. Namely, the regulating means 19 regulates the transfer of a fresh active developer sent from the 2nd agitating member 17 to the lower part of the 1st agitating member 16 to the rear part together with the 1st agitating member 16 and effectively agitates the fresh developer with a fatigue developer sent from a sleeve side to send the mixed developer to the rear part. Consequently, the developer obtained immediately after toner feeding is not measured by the sensor and the developer obtained after effectively agitating and mixing the developer always flowing from the 1st agitating member to the 2nd agitating member is measured, so that the accuracy of measurement can be obtained.

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]

-i, in the two-component developer used in this type of developing device, the amount of toner mixed with a certain 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 when the standard mixing ratio of carrier and toner' is met, 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 the voltage is low. If it is low, it is known that the toner concentration is high, so if a toner concentration sensor that detects changes in this voltage is installed, it is possible to constantly monitor the toner concentration. This toner concentration sensor is preferably provided facing the flow path of the developer flowing from the first stirring member to the upper surface of the second stirring member. That is, the first stirring member is used to thoroughly stir and mix the toner-depleted developer and the fresh developer on the front surface of the photoreceptor drum. This is because the developer is in the most favorable state for measurement.

However, due to the space within the developing section, the toner that is replenished based on the command of the toner concentration sensor falls on the flow path of the developer from the first stirring member to the second stirring member. If this continues, the developer immediately after the toner is replenished will go to the front of the toner density sensor, resulting in a collapse that makes accurate density measurement impossible.

[Purpose of the invention]

In view of the above points, this invention does not measure the developer immediately after toner is replenished by the sensor, but instead measures the developer that has been well stirred and mixed and always flows from the first stirring member to the second stirring member. It is an object of the present invention to provide a developing device that can obtain accuracy.

[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, in which the amount of toner supplied to the sensor portion is limited compared to the amount of toner replenished to other portions. Specifically, the sensor-corresponding part of the opening groove provided in the lower part of the supply chamber is configured to be cold with a shielding member or the like.

〔Example〕

Next, this invention will be explained based on the embodiments shown in FIGS. 1 to 4.

In FIG. 1, reference numeral 10 denotes an image forming unit of a copying machine, and inside the image forming unit 10, a photoreceptor drum 11 is located at the center, and surrounding areas are a charging section 12, a developing section 13, 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 11, and is not provided in this unit IO.

゛ The developing section 13 includes a developing sleeve 15, a first stirring member 16 that performs main stirring, and a second stirring member 1 that performs auxiliary stirring.
It has 7. The developing sleeve 15 is connected to the photosensitive drum 1
1, and has the function of electrostatically adsorbing the developer onto the drum surface and developing the electrostatic latent 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 11.
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 16 and moves backward. This is to prevent the developer from being put away and to mix well with the fatigued 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 adjustment of the gap G of the doctor means 18 and the adjustment of the gap S of the regulating means 19 can be performed 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. and is guided to the upper part of the second stirring member 17, where it is stirred 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 partition plate 20 descends along the partition plate 20 as shown by the arrow B, and is sent to the lower part of the first stirring member 16, where it is sent to the lower part of the first stirring member 16, where it It is designed to merge with the developed developer as shown in 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 that a flow rate regulating means (in this embodiment, an opening 21 provided in the partition plate 20) for the developer, which is the object to be detected, is provided on the upstream side of the toner concentration sensor 23, so that the flow rate of the developer flowing in front of the sensor is controlled. This is because the flow rate becomes quantitatively stable. 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. The falling point is on the inclined plate 22 continuous to the opening 21 of the partition plate 20, that is, on the developer flowing from the first stirring member 16 to the upper surface of the second stirring member 17, as shown in the third figure.

As shown in FIG. 4, a part of the opening groove 29 provided at the lower part of the supply chamber 26 along the development width direction is covered with a shielding member 32 at a portion corresponding to the sensor installation portion (approximately the center of the development width). ing. That is, the amount of toner replenished to the front surface of the toner concentration sensor 23 is limited compared to the amount replenished to other parts, so that the developer immediately after being mixed with replenishment toner is not carried to the front surface of the toner concentration sensor 23. This is what I did. This shielding member 32 may be made of a thin plate such as a PET base, or may be formed in such a way that the portion where the shielding member is to be provided is not opened from the beginning when forming the supply chamber 26.

According to the above embodiment, the developer falling from the supply chamber due to the rotation of the supply roller 31 flows down on the inclined plate 22 continuous to the opening 21 of the partition plate 20 as shown by the dots in FIG. However, it is not replenished to the part corresponding to the sensor installation part, and the sensor does not measure the developer immediately after toner is replenished.

(Effects 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.
Since the present invention is characterized in that a means is provided for limiting the amount of toner supplied to the sensor section compared to the amount of toner supplied to other parts, the developer immediately after toner is replenished is not measured by the sensor; The measurement is performed using the well-stirred and mixed developer that always flows from the first stirring member to the second stirring member, which has the excellent effect of providing measurement accuracy.

[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. 4 is a sectional view showing the opening groove of the toner replenishing chamber and the shielding member, and FIG. 5 is a perspective view thereof. 15.--Developing sleeve 16--First stirring member 17--Second stirring member 20--Partition plate 21--Opening 22-Slanted plate 23--Toner concentration sensor 26--Replenishment chamber 29- - Opening groove 30 - End member 31 - Replenishment roller 32 - Shielding member (supply amount limiting means) Fig. 4 Fig. 5

Claims (2)

[Claims] (1) In a developing device equipped with a sensor that controls toner concentration using a magnetic permeability change detection method, a means is provided for limiting the amount of toner supplied to the sensor section compared to the amount of toner supplied to other parts. A developing device characterized by: (2) The limiting means is configured by shielding a portion of an opening groove provided along the development width in the lower part of the toner supply chamber that corresponds to the sensor installation portion. developing device.