JPH0134202Y2 - - Google Patents

Description

[Detailed explanation of the invention] (1) Technical field of the invention The invention relates to a developing device that controls the toner concentration in the developer, and in particular detects changes in the level level on the surface of the developer due to volume changes. The present invention relates to a developing device that controls density.

(2) Prior art In an image processing method that includes a step of forming an electrostatic latent image such as electrophotography and developing it to make it visible, there is a method for developing a latent image formed on an electrostatic image carrier such as an electrophotographic photoreceptor. There are liquid development, dry development, etc. Currently, among dry development, carriers such as iron powder,
Two-component mixed powder developers consisting of toner are widely used.

For example, in a dry electronic copying machine using such a two-component developer, it is required to maintain a constant mixing ratio of toner and carrier, that is, toner concentration, in order to always obtain high-quality images.

(3) Problems with the Prior Art Normally, when the toner concentration in the developer changes, the volume of the developer also changes, and in the case of the same developer container, the surface level of the developer also changes. In a level detection method that controls toner density using such surface level fluctuations, for example, when replacing the developer, a predetermined method is used to prevent image quality from deteriorating due to slight changes in toner density. The following methods have been proposed as methods for resetting or changing the toner density to a toner density suitable for obtaining good images.

Display sensor detection results in a designated location
Attach the LED, add developer little by little, and
The surface level can be reset at the optimum value of the toner concentration by visually observing the change in the toner concentration, or the sensor can be used in a variable manner, i.e. the volume of developer with the optimum toner concentration remains constant and the surface level There is a known configuration in which the sensor is mechanically moved up and down in the vicinity of this surface level while the surface level is kept constant to determine the position of change, thereby resetting the toner density.

However, the method of adding developer little by little for setting has the disadvantage that the service person or the user himself/herself gets his or her hands dirty. There is also a risk of spilling the developer inside the copying machine or on the floor.

Normally, the developing device is installed inside the copying machine, so each time a small amount of developer is added, the developing device must be taken out of the machine using an appropriate means, so it takes a considerable amount of time to reset the toner density. This requires time and effort.

Further, in the method of mechanically moving the detection sensor up and down to reset or change settings, there is a problem in terms of accuracy. In other words, the change in developer surface level with respect to toner concentration is very subtle;
In other words, in a developer container that stores a relatively large amount of developer, the surface level changes very little in response to an increase in developer volume, so depending on the vertical movement of the mechanical sensor, it is difficult to roughly reset or set the toner density. It has the disadvantage that only changes can be obtained. In addition, the developing device must be taken out of the machine for setting, which has the same drawback as the former, which requires time and effort.

(4) Purpose of the invention In view of the above-mentioned conventional drawbacks, the purpose of the invention is to control the toner concentration by detecting the surface level of the developer by utilizing the fact that the volume changes due to changes in the toner concentration in the developer. In this method, by installing a partition and a cam to raise and lower the developer level,
It is an object of the present invention to provide a developing device in which the setting position of toner density can be easily changed and controlled with high precision.

(5) Key Points of the Invention The purpose of this invention is to provide a container for storing a developer consisting of at least toner and carrier, and a container for storing the developer, which is composed of at least toner and carrier, and to transfer the developer in the container to an image carrier on which an electrostatic latent image is formed. a developing means for causing the toner to adhere to the electrostatic latent image portion of the image carrier by contacting with the image carrier;
a detection means for detecting whether the surface level of the developer has reached a predetermined position in the container; and a control means for controlling replenishment of toner into the container based on a detection output of the detection means. This is achieved by providing a developing device characterized in that the developing device is equipped with means for varying the surface level of the developer.

(6) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a developing device according to the present invention.

In FIG. 1, a conductive sleeve 2 made of a non-magnetic material is configured to rotate, for example, clockwise, around a fixed magnet roll 3 having a plurality of magnetized portions in the axial direction. Further, on the circumference of the sleeve 2, a plurality of magnetic brushes 11 are formed on the circumference of a magnetized portion provided on the magnet roll 3, and are rubbed on the surface of the photoreceptor 1. The attached developer is conveyed clockwise as the sleeve 2 rotates, and is sent out in fixed amounts by a regulating plate 6 provided below.

A stirring roll 5 rotates in the developer in order to maintain the developer composed of toner and carrier stored in the development hopper 4 at an even concentration, and also to control the surface level position of the developer. A cam 15 is provided partially embedded in the developer.
In addition, in order to adjust the surface level by the cam 15 from the outside of the main body, a knob 13 is attached so as to engage with the cam via a hinge portion 14.

For example, a vibration plate 16 and a toner sensor 10 electrically connected to the vibration plate 16 are installed at a position covering the surface level of the developer, that is, the level of the lower surface A and the higher surface B. When the amount of developer in the developing hopper 4 is low, the toner is placed at the bottom of the replenishing hopper 8 so that the toner falls from within the replenishing hopper 8 attached to the upper part of the developing hopper 4 into the developing hopper 4. A supply roll 9 is provided above the outlet.

After an electrostatic latent image is formed on the surface of the photoreceptor 1 by charging and exposure (not shown), the ears of the developer sleeve rub against the electrostatic latent image, and the toner in the developer becomes photosensitive due to Coulomb force. It is electrostatically attracted to the body surface and visualized. Since the toner in the developer after this development is consumed, the toner concentration in the developer decreases, and is transported by the rotation of the sleeve 2 and separated from the sleeve 2 by the partition plate 12. The developer separated from the sleeve 2 is mixed with other developer by the rotation of the stirring roll 5, and is again applied to the surface of the photoreceptor 1 for visualization.

By repeating the above cycle, the toner concentration of the developer in the entire developing device decreases significantly, the volume of the developer decreases, and the surface level decreases to the lower surface A.

The toner sensor 10 is fixed to the developing hopper 4. When the surface level of the developer decreases, that is, when the lower surface level A decreases, the toner sensor 1
The diaphragm 16 of No. 0 vibrates and outputs a toner replenishment signal. In response to the toner replenishment signal, the replenishment roll 9
rotates, toner falls from the replenishment hopper 8 into the developing hopper 4, and the toner is replenished. The fallen toner is mixed with the developer by the agitation roll 5 and gradually becomes highly concentrated, the volume of the developer increases accordingly, and the surface level gradually increases, approaching the high surface B. Then, the vibration plate 16 of the toner sensor 10 stops vibrating, and the output of the toner replenishment signal also stops, so the replenishment of toner from the replenishment hopper 8 is also stopped.

By repeating the above cycle, the developer concentration is controlled within a predetermined range, but in the present invention, a cam is further provided to detect the toner concentration with high precision.

That is, in FIG. 1, a cam 15 is partially embedded in the developer, and when the knob 13 is rotated by an operation from outside the main body, the cam is rotated via the hinge portion 14. For example, when a smaller amount of developer than a predetermined reference amount is put into the development hopper 4 and stirred, if the development level has decreased to near the lower surface A, the vibration plate 16 of the toner sensor 10 vibrates. ing. Then, when the knob 13 is rotated to rotate the cam 15 to increase the buried portion of the cam 15, the volume of the developer increases by the increased portion of the buried volume of the cam 15, and the surface level also rises by a small amount. This fine movement operation at the surface level can be performed by a relatively rough operation of the knob 13 in conjunction with the cam 15. Therefore, the stoppage of the diaphragm at an accurate level of the developer surface concentration can be determined using, for example, an LED. By adjusting it, it becomes possible to set it with high precision.
In other words, after setting the developer level with high precision,
By fixing the knob 13, accurate toner density can be obtained from now on. Further, even if the setting of the surface level of the developer is mistaken, readjustment is possible by simply returning the knob 13 to its original state.

FIG. 2 is a schematic cross-sectional view of another embodiment of the present invention.

In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals, and redundant explanation will be omitted.

In this embodiment, instead of embedding the cam directly in the developer, an elastic member 17 made of rubber or the like is provided at the bottom of the developing hopper 4, and the cam to which the knob 13 interlocks is brought into contact with the lower side of the elastic member 17. The rotation of the developer forcibly raises an elastic member 17 such as rubber upward to raise the surface level of the developer, thereby making fine adjustments.

As described above, in both the first and second embodiments, a method is used in which the surface level is set by increasing the developer level, but it is also possible to implement the method by lowering the developer level and setting the surface level. Of course, it is also possible.

(7) Effects of the invention As described above, when the invention is used, toner is mechanically replenished based on the output signal from the toner sensor, which has the effect of preventing contamination of the hands or the inside of the machine.

Furthermore, by using the present invention, anyone can easily set the surface level according to a predetermined concentration by simply turning a knob.

Further, when the present invention is used, it becomes possible to finely control the surface level of the developer by rough operation of the knob, which has the effect of allowing the surface level to be set with high precision.

Furthermore, when the present invention is used, the knob can be taken out of the machine, so the surface level can be adjusted while the developing unit is installed, which has the effect of allowing settings to be made in a short time.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a developing device using the present invention, and FIG. 2 is a schematic sectional view of a developing device in another embodiment of the present invention. 1... Photoreceptor, 3... Magnet roll, 4... Developing hopper, 5... Stirring roll, 8... Supply hopper, 10
...Toner sensor, 13...Knob, 15...Cam, 16
...Vibration plate, 17...Elastic member.

Claims (3)

[Scope of utility model registration request] (1) A container containing a developer consisting of at least toner and carrier, and a container in which the developer in the container is brought into contact with an image carrier on which an electrostatic latent image is formed, and the developer is brought into contact with an electrostatic latent image portion of the image carrier. a developing means for adhering the toner; a detecting means for detecting whether the surface level of the developer has reached a predetermined position in the container; A developing device comprising a control means for controlling toner replenishment,
A developing device comprising means for varying the surface level of the developer. (2) A claim for registration of a utility model characterized in that, as a means for varying the surface level of the developer, a member for changing the surface level of the developer is provided in the container so as to be able to appear and retract from the developer. The developing device according to item 1. (3) A request for registration of a utility model characterized in that, as a means for varying the surface level of the developer, a part of the container is made of an elastic body, and a member for displacing the elastic body from the outside of the container is provided. The developing device according to item 1.