JPS63311283A - Developing device - Google Patents

Abstract

PURPOSE:To uniformize the flow of a developer and to accurately detect the concentration of toner by providing a supporting member, which suppresses the movement of an elastic screw in a carrier path direction, provided in a direction along the carrier path in a developer carrier means. CONSTITUTION:The developer carrier means has the screw supporting member 20, which suppresses the movement of the elastic screw 4 in the carrier path direction, provided in the direction along the carrier path. Namely, though the screw 4 has elasticity in a folded direction in the center part thereof, it is firmly supported by the supporting member 20 which does not have substantially elasticity in an axis direction, so that it is not made far apart from a toner concentration detection area even if it receives stress in case of carrying the developer. Then, the respective blades of the screw 4 can be always kept a distance from the detection area constant. Thus, the carrying quality of the developer in the detection area can be improved and the detection of the quantity of the developer can be precisely executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing device including a developer amount detection means for detecting the toner concentration of a developer made of toner and magnetic particles.

(Prior art) A latent image such as an electrostatic latent image or a potential latent image is formed on a latent image carrier, and the latent image is developed to obtain an image-formed product directly or indirectly (transfer method). Devices based on various principles and methods have been proposed and put into practical use.

In particular, a device that detects the concentration of the developer is often used in a developing device that develops the surface of a latent image carrier by carrying a developer containing 21R of toner and magnetic particles on a developer carrying member.

In the case of a developing device that uses a two-component developer consisting of toner and magnetic particles, only the toner is consumed during development, so the toner concentration of the developer will gradually decrease and the formed image density will decrease. This results in a decline in In order to always keep the toner concentration of the developer at an appropriate level regardless of toner consumption, it is necessary to quickly detect the current toner concentration of the developer, replenish the toner at the right time and in an appropriate amount based on the detected value, and replenish the entire developer by replenishing the toner. It is necessary to quickly uniformly and dispersely mix the developer and quickly transport the developer to the toner concentration detection section.

Therefore, this type of developing device requires a means for detecting the toner concentration of the developer in the developer storage section, a means for stirring and transporting the developer in the developer storage section, a replenishment toner storage section, and a means for stirring and conveying the developer in the developer storage section. A means for conveying the toner to the developer storage section is provided, the toner concentration detection means detects the developer toner concentration in the developer storage section, and the detected information is input to the control circuit, so that the toner concentration reaches a predetermined value. When the toner reaches the allowable lower limit, the replenishment toner conveying means is activated to introduce a portion of the toner in the replenishment toner storage section into the developer storage section. The replenishment toner is quickly mixed and dispersed throughout the developer in the developer storage section by the developer stirring/conveying means described above, and the above toner concentration is detected when the toner concentration of the developer rises to a predetermined value due to toner replenishment. If it is detected by the means, the operation of the replenishment toner conveying means is stopped, thereby automatically managing and controlling the toner concentration of the developer to a predetermined substantially constant value.

Therefore, one of the requirements for reliable and highly accurate toner concentration management control is the bulk density of the developer, which can be obtained by thorough stirring and mixing of the developer and removal of depletion layers, etc. uniformity. This is because even if the developer has the same toner concentration, a developer with a depletion layer or the like and a low bulk density tends to have a lower toner concentration detection value than a developer with a high bulk density.

A spiral elastic screw has conventionally been commonly used as a member of the developer conveying means of a developing device, and when this screw is rotated, it has the effect of pushing the developer toward the toner concentration detection area on the screw surface. However, at this time, the screw surface receives stress from the developer being transported, and since the screw is an elastic body, the screw blades tend to move away from the toner concentration detection area.

Once the screw blades have moved away, they attempt to return to their original positions once the stress they receive weakens.

In this way, if the flow rate of the developer is not uniform and the stress on the screw is uneven, the screw blades will vibrate as they approach and move away from the detection area. Therefore, the bulk density is also not uniform, making it difficult to accurately detect the toner concentration.

(Purpose of the invention) In view of the above problems, the present invention improves the amount of toner in the developer.

In particular, it is an object of the present invention to provide a developing device that can accurately detect toner concentration.

(Summary of the Invention) In order to achieve the above object, the present invention provides a non-linear developer transport path, a developer transport means disposed within the transport path and including a helical elastic screw, and a developer transport means disposed within the transport path, and a developer transport means disposed within the transport path. In the developing device, the developer conveyance means includes a support member provided in a direction along the conveyance path to suppress movement of the elastic screw in the direction of the conveyance path. It is a feature.

(Example) Hereinafter, an example of a developing device in an electrophotographic apparatus according to the present invention will be described based on the drawings.

FIG. 1 is a schematic front view of an example of the developing device *i according to the present invention, FIG. 2 is a cross-sectional view of the developing device, and FIG. 3 is an enlarged explanatory view of a detection section of the developing device.

In this developing device, the inside of the developer container 1 is partitioned by a partition wall into a toner storage portion and a developer storage portion C that stores a two-component developer containing toner and magnetic particles. The toner stored in the toner storage part and the developer in the developer storage part C are omitted from the diagram. The developer storage section C is connected to the partition wall 7.
It is divided into a developer stirring section and a developer supply section to the sleeve 2, which will be described later. This partition wall 7 also serves as a scraping member for scraping off the developer on the sleeve 2.

The developer on the sleeve 2, which once contributed to the development,
The developer stirring/conveying area A is completely scraped off by the partition wall 7 and is removed from the developer carrying area by the conveying means.
transported to. On the other hand, the toner stored in the toner storage section is moved by rotating the toner conveying member 6.
Toner is replenished into the developer storage section C from the toner replenishment port 5.

A sleeve 2 is disposed inside the developer storage section C, and is composed of a developing sleeve 21 made of a non-magnetic material and containing a magnet roll 22.N+, Nt, S+
, Sa indicate the magnetized position of the Macnet roll 2□. The magnet roll 2° is fixedly supported at both ends and does not rotate, and the developing sleeve 2. is rotated around the magnet roll 22 at a predetermined circumferential speed in the direction of the arrow.

A screw 4 serving as a developer stirring/transporting means arranged approximately parallel to the developing sleeve 2 is fixed to a support member 20 having elasticity only in the bending direction, and is fixed to a support member 20 having elasticity only in the bending direction. It is arranged on the longitudinal extension of the developing sleeve 2 and extends over the developer stirring/transporting area A which is outside the carrying area.

The screw 4 collects the developer (new toner and toner collected from the surface of the sleeve 2) located below the container 1.

A conveying pipe 31 that is rotatably driven to agitate and convey carrier) in the upward direction shown in the figure and has a screw.
, 30th, the developer is sent in the direction of the arrow through the common opening 32. The developer conveyed to the left in FIG. 1 by the screw 3 is supplied toward the developing sleeve 2 from the developer supply port 9.

The cross-sectional area SA of the transport section A as the second transport means perpendicular to the transport direction is smaller than the cross-sectional area S perpendicular to the transport direction of the transport section C as the first transport means.

Furthermore, since the screw 4 is firmly supported by a support member (for example, a rod-shaped spring) 20 disposed at the center thereof and having elasticity in the bending direction but substantially no elasticity in the axial direction, Even if the developer is subjected to stress during transport, it will not move away from the toner concentration detection sensor. Therefore,
Each blade of the screw 4 always maintains a fixed distance from the detection area, so that the flow of the developer becomes uniform, that is, the bulk density of the developer becomes uniform.

Furthermore, if a rod-shaped coil spring 20, for example, which can store a torsional moment in the center of the conveying screw 4 and release a part of the torsional moment in the axial direction, is used as a support member for the conveying screw 4, the coil spring 20 can be driven one rotation. Not only does it transmit the rotational torque to the screw 4 when it is detected, but it also has the effect of pressing the blades of the screw 4 toward the detection side, contributing to the removal of the depletion layer.

Furthermore, the central portion of the screw, which is conventionally hollow, in the conveying passage, that is, the portion not receiving the conveying force, can be filled with the coil spring 20, and partial stagnation of the developer can be prevented.

Here, an example of the toner concentration detection means B is shown in FIG.
10 is a lamp, and 11 and 12 are sensors for measuring the amount of light reflected by the developer and the amount of direct light from the lamp, respectively.The housing of the toner concentration detection means B is made of a light-shielding member. Light entering each sensor14,1
The amount of light No. 5 is converted into voltage by a predetermined circuit. Let the voltages from sensors 11 and 12 be Vb and Vc, respectively,
When a predetermined concentration of developer is present.

If the circuit is set to 7A so that Vb=Vc, then vb will increase or decrease as the toner density increases and Vc will always remain constant.

By repeating the operation of stopping toner replenishment when Vb>Vc and starting toner replenishment when Vb<Vc,
The toner concentration of the developer can be controlled to a certain predetermined value.

In the above embodiment, the member 20 that supports the conveying screw 4 is not limited to a rod-shaped spring, but may also be made of an elastic member such as a rubber material. It may be either a fixed fixed end or an unfixed free end.Furthermore, the polar configuration and rotation direction of the developer carrying member, the developer concentration detection means, the Wl stirring and
The shape of the conveyance area is also not limited to the above embodiment.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, it is possible to improve the conveyance of the developer in the detection area, and the amount of developer can be detected with high precision, so that the amount of developer can be detected with high precision. It is possible to obtain stable, high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of an example of the developing device of the present invention, FIG. 2 is a cross-sectional side view of the developing device, and FIG. 3 is an enlarged configuration diagram of a toner concentration detection section of the developing device. 2...Developing sleeve, 3.4...Screw, 20
-...Screw support member.

Claims (2)

[Claims] (1) A developing device having a non-linear developer conveyance path, a developer conveyance means disposed within the conveyance path and including a helical elastic screw, and a developer amount detection means disposed on the conveyance path. A developing device, wherein the developer conveyance means includes a support member that suppresses movement of the elastic screw in the direction of the conveyance path and is provided in a direction along the conveyance path. (2) The developing device according to claim 1, wherein the supporting member is capable of accumulating a torsional moment and releasing a part of the torsional moment in the axial direction. Device.