JPS6318379A - Developing device - Google Patents

Abstract

PURPOSE:To detect the toner concentration of a developer always with high accuracy by forming a transparent window for a toner concentration detector on a developer carrying thickness regulating member and forming a smooth curved surface connected to the ceiling surface of a developer container on the upper part of the regulating member. CONSTITUTION:Excess developer is raised along the inwall surface of the blade developer carrying thickness regulating member 109 in the arrow P2 direction, after scrapping the surface of the transparent window 109a so as to clean the surface of the window 109a, guided by the curved surface 109b of the blade 109, inverted in the direction along the ceiling surface 104a of the developer container 104, and then dropped in the arrow P3 direction. The curved surface 109b acts so as to increase the flow rate of the developer slided on the surface of the window 109a and interrupt the adhesion of the developer to the window 109a. Infrared rays or the like are radiated from the toner concentration detector 111 through the window 109a, the reflected light from the developer is converted into an electric signal and a developer toner concentration detecting signal is generated. Consequently, the toner concentration can be accurately detected and the toner concentration in the developer can be controlled always at a fixed value.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a developing device to be installed in an image forming apparatus such as an electrophotographic device, and particularly to a developing device that uses a two-component developer. The present invention relates to an improved developing device capable of controlling density.

[Background of the invention]

In a developing device that uses a two-component developer consisting of a mixture of magnetic particles and toner particles, the toner particles in the developing process are consumed every time a developing operation is performed, and magnetic particles (i.e., carriers) remain. The toner concentration in the developer decreases with each development operation. Therefore, in order to keep the toner concentration in the developer at a constant value, it is necessary to always accurately detect the toner concentration of the developer being used in the developing device and replenish toner according to the detection result. Therefore, in order to detect the toner concentration of the developer being used in the developing device, for example, a method for detecting the developing device or developer concentration as shown in FIG.
It is disclosed in Japanese Patent No. 853.

In FIG. 5, 1 is a photosensitive drum rotating in the direction of the arrow, and 2 is a magnet arranged parallel to the photosensitive drum 1, facing the circumferential surface of the photosensitive drum 1.

A troller 3 denotes the magnet; a developing sleeve rotatably fitted onto the troller 2 and rotated in the direction of arrow B in synchronization with the photosensitive drum 1 by a drive mechanism (not shown); 4 a developing sleeve that rotates toner and magnetic particles; 5 is a screw-type stirrer for stirring the developer mixture in the container 4; 6 is a container for storing toner T't- to be replenished into the developer container 4; The toner supply tank 7 is the toner supply tank 6.
A screw feeder 8 is used to supply toner T into the developer container 4, and a motor 8 is used to rotate the screw feeder 7.

9a is a transparent glass window 9b located directly above the developing sleeve 3 and extending tangentially (horizontally) to the circumferential surface of the sleeve 3;
The main body of the developer concentration sensor 9 has an infrared LED 9c.
9d is an infrared transmission filter, 9e is a light receiving element, 10 is a light emitting element control circuit, 11 is a differential amplifier,
12 is a reference value generator (reference voltage source). In the configuration shown in FIG. The developer is irradiated with light generated from the light emitting element 9C through the transparent glass window 9b, and this light is reflected by the developer adhered on the developing sleeve 3, and the reflected light is passed through the infrared transmission filter 9d.
The light is input to the light receiving element 9e through the light receiving element 9e and converted into an electric signal
The electrical signal is compared with a reference value in a differential amplifier 11, and the difference is amplified and used as a control signal for the motor 8.

Although the developer concentration detection method shown in FIG. 5 is theoretically effective, in the configuration shown in FIG. The surface of the transparent glass window 9b is rubbed by the raised portion DI of the developer.
Since the developer is prevented from adhering to the surface of the transparent glass window 9b, it is necessary that the position of the raised portion Dl relative to the transparent glass window 9b is always stable. Since it is impossible to always control the
The known developing device or toner concentration detection method shown in FIG. 5 has the disadvantage that the developer tends to adhere to the surface of the transparent glass window 9b, making it impossible to always perform highly accurate detection. Ta.

[Purpose of the invention]

An object of the present invention is to provide improved practicality in which the toner concentration of the developer being used in the developing device can be detected at a high level at all times, and the amount of toner to be replenished to the developing device can be accurately controlled at all times. It is an object of the present invention to provide a developing device with high performance.

[Summary of the invention]

The improved developing device according to the present invention is characterized by a wall-like or plate-like developer carrying surface that intersects with (or perpendicularly crosses) the developer carrying surface of a developer carrying body such as a developing sleeve. A transparent window is provided in the thickness regulating member, and a developer toner concentration detector including a light emitting element and a light receiving element is disposed facing one side of the transparent window, while above the developer carrying out thickness regulating member. The portion is formed with a smooth curved surface that connects to the ceiling surface of the developer container.

In the developing device according to the present invention, the surface of the transparent window is constantly rubbed by the excess developer rising from the developer container along the surface of the regulating member. Therefore, the toner concentration of the developer can be detected with high precision at all times, and the toner concentration in the developer can be controlled with high precision.

Further, in the developing device of the present invention, in order to increase the flow rate of the excess developer, a curved surface that smoothly connects with the ceiling surface of the developer container is formed in the upper part of the regulating member, so that the surface of the transparent window can be slid. The flow rate of the developer to be rubbed is high, and as a result, the developer is less likely to adhere to the transparent window, and the circulation of the developer within the developer container can be increased.

[Embodiments of the invention]

An embodiment of the developing device of the present invention will be described below with reference to FIGS. 1 to 4.

In FIG. 1, 101 is a photosensitive drum (that is, an electrostatic latent image carrier) that rotates in the direction of the arrow, 102 is a magnet, a troller, and 103 is a developing sleeve that rotates in the direction of arrow B.
104 is a developer container containing the developer Dt; 105 is a developer agitator; 106 is a toner replenishment tank; 107Fi is a screw feeder for replenishing toner T; 108 is a drive for the screw feeder. A motor 109 is a blade for controlling the layer thickness of the developer adsorbed onto the developing sleeve 103 (that is, a developer discharge thickness regulating member).

110 is a bias power supply for applying a developing bias voltage to the developing sleeve 103; 1091 is a transparent window formed on the wall of the blade 109; 111 is one surface of the transparent window 109m (the surface not in contact with the developer); A developer toner concentration detector 112 installed facing the motor 10 amplifies the difference between the output signal of the toner concentration detector 111 and a reference value.
This is a control circuit that generates a control signal of 8.

As shown in FIGS. 1 and 2, a bent surface 109b is formed at the upper end of the grade 109 and smoothly connects to the ceiling surface 104a of the developer container 104.
9b, as will be clear later, the transparent window 109m
It has a function of increasing the flow rate of the excess developer that scratches the surface of the transparent window 109a, and also increases the unit time flow rate of the excess developer that scratches the surface of the transparent window 109a.

As shown in FIG. 3, the toner concentration detector 111 includes a light emitting element 111b, a light receiving element 111c, a reference signal generating light receiving element 111d, slits 111 and 111f, etc. inside the detector geddy 1111. , applicable? The front opening of the “D 10” is a transparent window 10 with a blade 109.
The geddy 111a is removably attached to the blade 109 so as to match 9alC.

In addition, in FIG. 1, the developing device of the present invention is constructed by A.
This is the part excluding the photosensitive drum 101.

In the apparatus shown in FIG. 1, when the developing sleeve 103 rotates in the direction of arrow B in synchronization with the rotation of the photosensitive drum 1010, the developer in the developer container 104 is transferred to the developing sleeve by the electrostatic attraction force of the outer peripheral surface of the developing sleeve 103. As the circumferential surface of the sleeve moves while being attracted by the arrow P in FIG.
After rising inside the developer container 104 in the direction of
4 is carried out to the outside and supplied to the outer peripheral surface of the photosensitive drum 101. On the other hand, excess developer is removed from the blade 1 as shown by arrow P1.
After scraping and cleaning the surface of the transparent window 1091 while rising on the inner wall surface of the blade 109, the curved surface 10 of the blade 109
9b, it reverses in the direction along the ceiling surface 104a of the developer container 104, and then descends in the direction of arrow P3.

At this time, infrared light or the like is irradiated from the light emitting element 111b through the transparent window 109a to the developer immersed in the transparent window 109a and rising, and after this infrared light is reflected by the developer, the reflected light is converted into an electrical signal by the light receiving element 111c. On the other hand, the light emitted rearward from the light emitting element 111b passes through the pickpocket, )lllf, enters the reference signal generating light receiving element 111d, and is converted into an electrical signal in the light receiving element 111d.

The electric signal generated from the light-receiving element 111c and the electric signal generated from the reference signal-generating light-receiving element 111d are input to a control circuit 112, where the difference between the two human power signals is amplified and used as a control signal for the motor 108. The control circuit 112 outputs the signal. The reflected light from the developer has a phase or circumference I:I1. proportional to the toner concentration in the developer. Since the number and other components change, the toner concentration in the developer can be determined by comparing the signal generated by the light receiving element 111d for reference signal generation, into which the light generated by the light emitting element 111b directly enters, and the signal generated by the light receiving element 111c. An output signal representing the control circuit 112 will be generated.

Since the motor 108 is rotated according to the control signal, the screw feeder 107 is rotated to compensate for changes in toner concentration in the developer, and toner replenishment is completed! From 106, toner T is fed into the developer container 104 in an amount corresponding to the insufficient amount.

In the developing device of the present invention, unlike the conventional developing device or toner concentration detection device shown in FIG.
A transparent window is provided in a developer discharge thickness regulating member (i.e., a blade) having a surface in a direction perpendicular to the outer circumferential surface of No. 3;
Since the structure is configured such that the surface of the transparent window is rubbed by the developer that is not spewed out of the developer container, there is no possibility that the developer will adhere to the surface of the transparent window. Therefore, in the developing device of the embodiment described above, the toner concentration can be detected at a high degree and always stably, and the toner concentration of the developer in the developer container can always be maintained at a predetermined value.

FIG. 4 shows changes in the electrical signal generated from the light receiving element 111c in the above embodiment. As shown in FIG. 4, the output voltage of the light receiving element 111c is approximately proportional to the increase in toner concentration in the developer, and no abnormal fluctuations are observed. That is, in the developing device of the present invention, the transparent window 109 &
It has been proven that the developer does not adhere to the surface of the

〔Effect of the invention〕

As explained above, in the developing device of the present invention,
A transparent window is provided in the developer discharge thickness regulating member having a surface in a direction that intersects with the outer circumferential surface of the developing sleeve (that is, in the radial direction), and a light emitting element and a light receiving element are separated from each other by facing the back side of the transparent window. At the same time, a toner concentration detector is arranged on the upper end of the regulating member to increase the unit time flow rate of the developer that scrapes the surface of the transparent window and to prevent it from stagnation. Since the connecting curved surface is formed, it is possible to completely prevent the developer from adhering to the surface of the transparent window. Therefore, in the developing device of the present invention, the toner concentration in the developer can be maintained at all times. Accurate and stable detection is possible, and the toner concentration in the developer can always be controlled to a constant value.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of essential parts showing one embodiment of a developing device according to the present invention, FIG. 2 is an enlarged view of a part of FIG. 1, and FIG.
4 is a diagram showing the relationship between the output of the toner concentration detector and the toner concentration in the developing device shown in FIG. 1, and FIG. 5 is a sectional view taken along arrow I-III in the figure. It is a schematic diagram showing a detection method. 1.101... Photosensitive drum 2.102... Magne, troller 3.103... Developing sleeve 4.104... Developer container 5.105... Stirrer 6.106... Toner supply tank 7.107...Screw feeder 8.108...
・Motor 9...Developer concentration sensor 11...Differential amplifier 12...Reference value generator 109...Blade (developer discharge thickness regulating member) 109&...Transparent window 109b...Bending Surface 110... Power supply 111... Developer toner concentration detector 111b... Light emitting element 111c... Light receiving element 111d... Standard signal generation (for reference) light receiving element 112... Control Circuit Figure 1 Figure 2 Figure 3 Figure 4 Toner concentration (wt%)

Claims (1)

[Scope of Claims] A developer container containing a developer made of toner particles and magnetic particles, and a developer container arranged in an opening of the developer container and rotated upward so that the developer in the developer container can be rotated upward. a developer transporting body that transports the developer toward an electrostatic latent image carrier or the like outside the developer container; a wall-like developer discharge thickness regulating member having a surface in a direction that intersects with the developer container; , in a developing device configured such that excess developer rises along the surface of the developer discharge thickness regulating member and then reverses and descends into the developer container, the surface of the developer discharge thickness regulating member A transparent window is provided in the window, and a developer detector composed of a light-emitting element and a light-receiving element is arranged facing the outside of the transparent window. A developing device characterized by forming a smooth curved surface that connects to the ceiling surface of a container.