JPH04139472A - Developing device - Google Patents

Abstract

PURPOSE:To detect a residual developer in a developer circulating region with excellent precision by providing a pressure sensor detecting the residual developer between a developer drawing up magnetic pole and a developer regulating member, and on the outside in the longitudinal direction of the circulating path of a developer. CONSTITUTION:The pressure sensor 8 detecting the residual developer is provided between the developer drawing up magnetic pole 5 of a magnetic field generating means inside a developing container 3 storing the developer 4 supplied to a developer carrier 2, and the developer regulating member 7, and on the outside in the longitudinal direction of the circulating path of the developer 4. Thus, the residual developer in the developer circulating region can be detected with the excellent precision, and moreover, the deterioration of the developer is prevented without interfering and disturbing a developer flowing state, so that the developer is always and stably replenished and an excellent quality image without having the missing of an image, a line, and irregularities is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a developing device in an electrophotographic device and an electrostatic recording type copying device, and particularly relates to a means for detecting the amount of developer in a developing device and a developing device. This invention relates to an improvement in a drug replenishment means.

[Prior Art] Conventionally, a developing device has a device that detects the remaining amount of developer.
A piezoelectric sensor detects the remaining amount by converting changes in powder pressure depending on the amount of developer into pressure-voltage, and a remaining amount detects changes in developer volume as changes in resistance by capacitance and voltage measurements. Sensors, etc. have been put into practical use.

Further, a necessary amount of developer stored in a hopper is supplied to a developing container.

Typically, developing devices with these configurations use a configuration in which the developer is conveyed from a developer storage hopper to a position where a developing sleeve, which serves as a developer carrying and conveying material, is located using a feeding member such as a stirring rod or a screw. ing.

In particular, in the case of piezoelectric sensor detection, the remaining amount detection sensor was often installed in the area where the stirring bar moves to convey the developer close to the developing sleeve or inside the developer storage hopper.

Further, when it is desired to perform detection near the developing sleeve, a detection sensor is sometimes installed in a portion where developer is circulated intensively.

[Problem to be solved by the invention] However, in the above conventional technology, the piezoelectric sensor is located at the installation position or near the stirring system, and does not measure the amount of developer that actually contributes to development, and does not measure the amount of developer that actually contributes to development. There was a problem in that the remaining amount detection level decreased in accuracy because it was greatly affected by the conveyance state. In addition, in order to improve the accuracy of detecting the remaining amount of developer, in order to ensure that it contributes to development, a detection sensor is installed in an area where developer circulation is intense. There was a problem that the developing efficiency of the area changed or decreased, causing unevenness on the image.

The present invention aims to solve the above problems. In other words, the present invention makes it possible to accurately detect the amount of developer remaining in the developer circulation tilted wall, prevents deterioration of the developer without disturbing or disturbing the developer flow state, and maintains a stable state at all times. It is an object of the present invention to provide a developing device capable of replenishing development and obtaining high-quality images without image omissions, deviations, or unevenness.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a developing device including a fixed magnetic field generating means and a developer carrier that moves surrounding the fixed magnetic field generator, in which the developer carrier It is located between the developer pumping magnetic pole, which is a magnetic field generating means in the developer container that stores the developer supplied to the developer, and the developer regulating member, and is located outside in the longitudinal direction of the developer circulation path to control the amount of developer. It is assumed that a pressure sensor for detection is provided.

[Function] According to the present invention, between the developer pumping magnetic pole of the magnetic field generating means in the developer container that stores the developer to be supplied to the developer carrier and the developer regulating member, Since a pressure sensor for detecting the amount of developer is installed on the outside in the longitudinal direction of the circulation path, the amount of developer remaining in the developer circulation area can be detected with high accuracy. This prevents deterioration of the developer, provides stable developer supply at all times, and provides high-quality images without image defects, streaks, or unevenness.

[Example] FIG. 1 is a sectional view showing a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a fixed magnetic roller as a magnetic field generating means with appropriately arranged magnetic poles, and is surrounded by a stainless steel non-magnetic sleeve 2 which is a developer carrier rotating in the direction of arrow a. The magnetic toner 4 contained in the developer container 3 is attached to the surface of the sleeve 2 by the pumping magnetic pole 5 of the magnet roller 1, and is conveyed in the direction of arrow a by rotation of the sleeve 2.

The conveyed toner is coated onto the sleeve 2 to an appropriate thickness by the magnetic field between the magnetic blade 7, which is a developer regulating member, and the cut magnetic pole 6, which is disposed opposite to the cut magnetic pole 8i6 of the magnet roller 1. Further, the toner layer on the sleeve 2 is conveyed to a developing area facing a photosensitive tram 12 as an image carrier rotating in the direction of the arrow 2, and is developed there.

On the other hand, the toner that is blocked from passing by the magnetic blade 7 is pushed upward along the magnetic plate 7 and the wall surface of the developer container 3 by lift force, and the balance between this lift force, the viscosity of the toner, and gravity is broken, as shown in the figure. It falls as shown by arrow C.

In this way, on the upstream side of the blade 7 in the rotational direction of the sleeve, there is always movement of toner while the sleeve 2 is rotating. Furthermore, even when the toner pumped up by the pumping magnetic pole 5 runs out, the toner pool formed by the toner circulation cycle on the upstream side of the blade 7 remains until the end and supplies the coated toner to the development position. Therefore, by providing a pressure sensor 8 between the position of the toner pumping magnetic pole 5 and the plate 7, the amount of toner in the developer container 3 can be minimized, and an appropriate amount of toner can always be held in the developer container 3. . Furthermore, as mentioned above, toner movement is active in this area, encouraged by magnetic force, so even when using toner with low fluidity, movement may occur due to toner bridging or adhesion of toner to the sensor surface. Defects and malfunctions can be prevented. moreover,
The amount of residual toner in the developer container 3 is detected by the combination of the gap created between the pressure sensor 8 and the sleeve 2 and the position of the pressure sensor 8 between the pumping magnetic pole 5 and the blade 7. The amount of toner can be selected to an appropriate value.

In this way, the signal from the pressure sensor 8 can be used to issue a warning to the operator of the machine.

Furthermore, by inputting the signal from the pressure sensor 8 arranged as described above for detecting the amount of toner to the control circuit of the driving means of the magnetic roller 9 for toner replenishment, a stable small amount toner replenishment type can be achieved. The developing device can be constructed as follows. This prevents the harmful effects of storing a large amount of toner in the developer container 3, such as toner deterioration caused by toner movement as the sleeve 2 rotates, and the particle size and charge amount of the residual toner on the sleeve 2. Unbalanced physical properties are minimized.

In FIG. 1, reference numeral 4a denotes replenishment toner stored in the hopper part a of the developer container 3, and the toner adhering to the magnet roller 9 rotating in the direction of the arrow d is stored in the hopper part 3a. The blade portion 10 becomes a toner brush 4b with a controlled thickness, and the toner that is blocked from passing is transferred to the developer container 3 by the blade portion 11 of the hopper portion 3a.
supplied within. Therefore, the gap between the plate portion 11 and the magnet roller 9 is narrower than the gap between the blade portion 10 and the magnet roller 9. The amount of toner replenishment and the replenishment gap can be controlled by a combination of three factors: the amount of rotation of the magnetic roller 9, the gap between the magnetic roller 9 and the blade portion 10.11, and the position of the pressure sensor 8. Alternatively, a sleeve may be provided around the magnet roller 9 and the two may be rotated relative to each other to replenish toner. Further, the developer regulating member may be a non-magnetic blade, a roller, or the like.

FIG. 2 is a plan sectional view taken along section line A-A in FIG. 1.

That is, both ends of the sleeve 2 are pivotally supported by the developer container 3, and a drive gear 13 is attached to one side of the extreme end. The sleeve 2 is configured to be rotated by rotating the drive gear 13 by a drive unit (not shown). Here again,
The closest gap between the drum surface and the sleeve surface is secured by the sleeve 2 and the drum gap regulating member 14.

A blade 7 which is a developer regulating member is also fixed to the developing device 3, and pressure sensors 8a and 8 are installed at intermediate points between the cutting magnetic pole 6 and the blade 7 and the toner pumping magnetic pole 5.
is installed. Here, the pressure sensor 8a is installed in a fluidized bed of toner, and when the toner restrained by the pumping magnetic pole 5 and the cutting magnetic pole 6 by rotation of the sleeve starts flowing in the direction of arrow C in FIG. The pressure sensor 8a detects the amount of toner by the pressure of the fluid toner. Since this pressure sensor 8a is located at a position that obstructs the toner flow, it is not suitable for cases where the toner flow is intense. This configuration is effective for low-speed image forming apparatuses in which toner flows slowly.

When the pressure sensor 8a is used in a high-speed image forming apparatus in which the toner flows intensely in a state where it is buried in a toner fluidized bed, toner adheres to the pressure sensor 8a itself and gradually becomes stuck and deteriorates. It becomes like this. Then, the toner flow in that part is disturbed and the toner is in the correct position; l! Since it has no charge, the development efficiency is lower than that of other parts, and streaks and unevenness appear on the image. Therefore, in a high-speed image forming apparatus, the pressure sensor 8 is installed so as to be embedded in the inner wall surface of the developer container 3 so as not to directly interfere with the toner flow. This toner pressure sensor 8 is configured so that its sensor surface is substantially flush with the inner wall surface of the developer container 3. The toner flow caused by the magnetic flux of the pumping magnetic pole 5 and the cutting magnetic pole 6 (see arrow C in FIG. 1) is in the direction of rubbing against the sensor surface, and the pressure changes depending on the amount of toner remaining, so the pressure sensor 8 detects the toner. It becomes possible to detect the amount of toner without disturbing the flow. Here, even if the toner is just rubbed, the pressure sensor 8 can measure the pressure change because the magnetic fields of the pumping magnetic pole 5 and the cutting magnetic pole 6 are formed near the pressure sensor 8, and the toner (magnetic) but,
Because it is flowing without being firmly magnetically restrained,
This is to apply pressure to the sensor surface.

With this configuration, there is no disturbance in the toner flow, there is no false detection due to toner adhesion to the pressure sensor 8, and it is possible to prevent streaks and uneven images.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

The developing device in this second embodiment includes a developer container, a developer carrier rotatably supported in the container, that is, a sleeve 2, and a fixed magnetic roller 1 disposed in the sleeve 2. and a blade 7 disposed above the sleeve 2 with a gap therebetween.

The developer container includes a developer container D1 and a seal member 2 above it.
The developer container D2 contains a developer (initial developer) consisting of a mixture of non-magnetic toner and magnetic particles. A non-magnetic toner (replenishment developer) TI is stored in the storage area. The developer T in the container Dl is replenished by the toner T1 in the toner container D2 falling by removing the sealing member 20, and is replenished by the rotating stirring member bent into a crank shape installed in the developer container D1. 21, the toner is stirred and mixed with the toner T1 and used for developing the electrostatic latent image formed on the photosensitive drum 12.

Note that the method for forming an electrostatic latent image on the photosensitive drum 12 is as follows:
This is not the gist of the present invention and may be formed by a known method.

The photosensitive drum 12 is supported rotatably in the direction of the arrow. Instead of the photosensitive drum 12, it is also possible to use an electrostatic latent image carrier such as a photosensitive belt.

The sleeve 2 is made of a cylindrical body made of a non-magnetic material such as aluminum, stainless steel, titanium steel, etc.
The container is placed so that its surface faces the photosensitive drum 12 through an opening on one side of the container.

It is rotatably supported in the direction of arrow a. sleeve 2
A minute gap constituting a developing section is provided between the photosensitive tram 12 and the photosensitive tram 12, and in this embodiment, the gap is set to 300 μm. The developer T is carried by the sleeve 2 in this developing section,
After being transported, the electrostatic latent image on the photosensitive drum 12 is developed. In place of the sleeve 2, a developer carrier made of an endless belt may be used.

A power source 22 is used to transfer the toner from the developer layer on the sleeve 2 onto the photosensitive drum 12 by forming an alternating electric field in the gap between the developing section and the sleeve 2 and the photosensitive drum 12. An alternating voltage is applied with the terminal connected to the ground side. The alternating voltage may be a symmetrical alternating voltage in which the peak voltage on the positive side and the negative side are the same, or an asymmetrical alternating voltage in which a DC voltage is superimposed thereon. Taking the asymmetrical alternating voltage as an example, to give a specific example, when the dark area potential of the latent image on the photosensitive drum 12 is -6'OOV and the bright area potential is -200V,
Superimpose DC voltage -300V to obtain peak and peak voltage V
pp==300~2000V 1. : It is an alternating voltage with a frequency f=200 to 3000 Hz. In this example, Vpp-1300 with a DC voltage of -300V superimposed
V.

An asymmetric alternating voltage of f = 1600) 1z is applied.

The developer carrying surface of the sleeve 2 is a rough surface having smooth recesses or a rough surface having a mixture of smooth recesses and fine recesses. The fixed magnet roller 1 is made of a permanent magnet, and is installed in the sleeve 2 so as not to move relative to the rotation of the sleeve 2. The magnetic roller 1 includes a magnetic pole N1 as a cut magnetic pole 6 for controlling the amount of developer supported on the sleeve 2 in cooperation with a blade 7, and a magnetic pole N1 as a cut magnetic pole 6 for controlling the amount of developer carried on the sleeve 2, and a magnetic pole N1 for transporting the controlled developer to the developing section. 7ii 1 pole S
l, a magnetic pole N2 for developing the electrostatic latent image on the photosensitive drum 12 with the developer conveyed to the developing section; and a magnetic pole N2 for conveying the remaining developer on the sleeve 2 after development into the developer container D1; It has a magnetic pole s2 as a pumping magnetic pole 5.

In this example, the strength of the magnetic pole is N1 of 850 Gauss, S
, is 950 Gauss, N2 is 750 Gauss, S2 is 550
It is set to Gaussian.

Note that these magnetic poles Nl, Sl, N2. S2 may have the magnetic properties of N and S reversed, or may be constructed of an electromagnet.

At least the tip of the blade 7 is made of a non-magnetic material such as aluminum, and the base end is connected to the toner container D2.
It is fixed to and placed above the sleeve 2 with a gap therebetween. The thickness of the developer layer supported on the sleeve 2 is
The size of the gap is smaller than the size of the gap between the sleeve 2 and the photosensitive drum 12 in a state where no magnetic force is applied by the magnetic pole N of the magnet roller 1. In order to form a developer layer with such a thickness on the sleeve 2, the size of the gap between the blade 7 and the sleeve 2 is preferably equal to or smaller than the gap in the developing section, but it is not larger. It is also possible that there is.

However, the size of the gap between the blade 7 and the sleeve 2 is 5
If it exceeds 00 μm, a large amount of developer will pass through this gap, making it impossible to form a developer layer with an appropriate thickness on the sleeve 2. On the other hand, if the size of the gap between the blade 7 and the sleeve 2 is less than 50 μm, the gap is likely to be clogged with magnetic particles in the developer. Therefore, the size of the gap between the blade 7 and the sleeve 2 is preferably 50 to 500 μm, preferably 100 to 350 μm. In this embodiment, the size of the gap between the sleeve 2 and the photosensitive drum 12 is 300 μm.
In contrast, the gap between the blade 7 and the sleeve 2 is set to 250μ.
It is set to m.

A regulating member 23 is provided inside the blade 7 in the developer container D1 in order to regulate the upper limit of the circulation of the developer generated in the container D1 as the sleeve 2 rotates. There is. A sleeve 2 is provided inside the container D1 to prevent leakage of the developer therein, especially the toner.
A magnetic member 24 protruding in the direction of the sleeve 2 to strongly form a magnetic brush by magnetic particles in the upper developer.
is provided. Further, an extending portion 25 extending downward from the sleeve 2 is provided on the container D11. moreover,
In order to more reliably prevent leakage of the developer, the container D1
A developer restraining member 26 is provided on the extending portion 25 on the sleeve 1 in a curved manner protruding toward the sleeve 2 . Further, the extending portion 25 is provided with a toner scattering prevention member 27 that protrudes in the direction of the sleeve 2 in a hook shape, and prevents toner scattering in the developing section by applying a voltage of the same polarity to the member 27. It is pressed toward the photosensitive drum 12 to prevent it from scattering.

The sleeve 2 includes a drive unit 15, a power supply 17, and a power supply control device 1.
The drive is controlled by 6.

In the above configuration, the pressure sensor 8 is installed on the inner wall surface of the developer circulation regulating member 23, and here,
The sensor 8 may be installed at any position in the longitudinal direction,
Since the pressure of the toner flow C is directly applied to the sensor surface and the sensor output changes depending on the amount of remaining toner, the detection accuracy is good. When it is detected from this sensor output that the amount of remaining toner is low, toner T1 is replenished by a toner replenishing device (not shown). Here, since a mixture of toner and carrier is used as the developer, when the toner is consumed and the developer volume decreases, the sensor 8 detects that the pressure on the sensor 8 decreases, and only the toner is used. It is meant to replenish. As a result, a sufficient amount of developing toner is always supplied, and an image without image omissions, streaks, or unevenness can be provided.

[Effects of the Invention] As explained above, according to the present invention, there is provided a magnetic field generator between the developer pumping magnetic pole of the magnetic field generating means in the developer container that stores the developer to be supplied to the developer carrier and the developer regulating member. In addition, since a pressure sensor for detecting the amount of developer is provided on the outside in the longitudinal direction of the developer circulation path, the amount of developer remaining in the developer circulation area can be detected with high accuracy, and the flow state of the developer can be obstructed. This has the effect of preventing deterioration of the developer without causing any disturbance, ensuring stable developer replenishment, and producing high-quality images without image omissions, streaks, or unevenness.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view showing the first embodiment of the present invention;
The figure is a plan sectional view taken along section line A--A in FIG. 1, and FIG. 3 is a side sectional view showing a second embodiment of the present invention. 1...Magnetic roller 2...Sleeve 3...Developer container 4...Toner 5...Pumping magnetic pole 6...Cut magnetic pole 7...Blade 8...Pressure sensor 12...Photosensitive Drum and 4 other people Figure 12: Photosensitive drum

Claims (1)

[Scope of Claims] 1. In a developing device having a fixed magnetic field generating means and a developer carrying member that moves surrounding the fixed magnetic field generating means, the magnetic field generating means in a developing container that stores developer to be supplied to the developer carrying member. A pressure sensor for detecting the amount of developer is provided between the developer pumping magnetic pole and the developer regulating member and on the outside in the longitudinal direction of the developer circulation path. Developing device. 2. The developing device according to claim 1, wherein the pressure sensor is embedded and installed so as to form substantially the same plane as the inner wall surface of the developing container. 3. The developing device according to claim 1 or 2, wherein the developer is replenished from the developer replenishment hopper to the developer container in response to a signal from a pressure sensor.