JP2006058377A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is free from a change in the supply and scoop of developer in an axial (longitudinal) direction regardless of a change in use environment, developer deterioration due to repeated use, and changes in the bulk height and fluidity of developer due to a change in toner concentration or the like. <P>SOLUTION: The image forming apparatus has a developing device designed such that two component developer composed of a mixture of toner and carrier is stirred by a stir member, the developer is held on a developer carrier in a layer and an image is developed by attaching toner to an electrostatic latent image formed on an image carrier disposed opposite the layer of developer on the developer carrier. The image forming apparatus is provided with a pressure detecting means for detecting pressure exerted to the layer thickness regulating member for making the thickness of the layer of developer uniform, and a scoop quantity control means for controlling based upon the detection result of the pressure detecting means a quantity of developer scooped from the developer carrier. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a developing device using a two-component developer such as a copying machine, a printer, a facsimile machine, or the like.

Conventionally, the developer transported from the developer container is supplied to the developer carrier by a stirring member provided in the developer container, and an excessive development of the developer adhering to the developer carrier is performed. A developing device that scrapes off the developer with a developer regulating member, sets the developer on the developer carrier to a predetermined thickness, and then supplies the developer to the latent image formed on the surface of the latent image carrier to perform development There is known an image forming technique having the following.
In recent years, the size of the apparatus has been increasingly reduced due to space saving. With downsizing, the arrangement of the above-mentioned members has become difficult. For example, the arrangement layout of the agitating member and the developer carrier is also close to each other, which affects the agitation member when supplying the developer by the agitating member. It is easy.
In particular, the developer feed fluctuation of the agitating member becomes the supply fluctuation to the developer carrier, and this is the fluctuation of the pressure on the developer carrier in the longitudinal direction, which is the rotation axis direction of the developer carrier. The developer layer changes after passing through the agent regulating member (doctor), and finally the image density fluctuation in the longitudinal direction, which is the rotational axis direction, occurs. These fluctuations vary depending on the bulkiness and fluidity of the developer, and in particular, vary due to fluctuations in the usage environment, deterioration of the developer due to repeated use, fluctuations in toner density, and the like.
In order to solve such a problem, various techniques have conventionally been proposed as methods for controlling image density unevenness. For example, Patent Document 1 discloses a developer transport amount detection unit that detects the amount of developer transported to a development region, a data storage unit that stores a signal from the developer transport amount detection unit, and the data storage unit. Development bias control means is provided to control the output image by changing the development bias based on the data in it, and a proper image is obtained by detecting the developer conveyance amount and controlling the development bias from the detection result. is there.
Also, for example, Patent Document 2 is based on a developer detection unit that detects the amount of developer that is carried on a developer carrier and conveyed to a portion facing the latent image carrier, and an output of the developer detection unit. Thus, a stable image can be obtained by providing a voltage adjusting means for adjusting the voltage applied to the developer regulating member and adjusting the applied voltage.
Japanese Patent Laid-Open No. 8-21729 JP-A-6-43749

However, although Patent Document 1 detects a change in the developer conveying amount in the circumferential direction of the developing sleeve and controls the developing bias based on the result, the fluctuation in the longitudinal direction that is the rotation axis direction of the developing sleeve is detected. Is not taken into consideration, and thus has the disadvantage of causing the above-described image density fluctuation. Such a defect is completely the same in Patent Document 2.
Therefore, the present invention has been made in consideration of the above-described circumstances, and the shaft is also affected by fluctuations in the use environment, developer deterioration due to repeated use, developer bulkiness and fluidity fluctuations due to toner density fluctuations, and the like. An object of the present invention is to provide an image forming apparatus that does not cause fluctuations in the supply (pumping) of developer in the direction (longitudinal direction).

In order to solve the above-described problems, the invention described in claim 1 includes a stirring member that stirs and transports a developer composed of toner and a carrier, and a developer carrying that retains the developer transported by the stirring member in a layered manner. And an electrostatic latent image on the image carrier disposed opposite to the developer carrier, and a layer thickness regulating member for making the thickness of the developer layer on the developer carrier uniform. In an image forming apparatus having a developing device for developing by attaching toner, pressure detecting means for detecting a pressure applied to the layer thickness regulating member, and pumping up the developer pumped by the developer carrier from the detection result of the pressure detecting means And a pumping amount control means for controlling the amount.
According to a second aspect of the present invention, the image forming apparatus according to the first aspect is characterized in that the pressure detecting means is arranged at predetermined intervals in the axial direction of the developer carrier.
According to a third aspect of the present invention, the image forming apparatus according to the second aspect is characterized in that an interval at which the pressure detecting means is disposed is equal to or less than a spiral interval of the stirring member.
The invention according to claim 4 is characterized in that the pumping amount control means is a pumping amount control means for changing the number of revolutions of the stirring member. And
According to a fifth aspect of the present invention, the pumping amount control means is a pumping amount control means for changing the developer amount in the developing device. The image forming apparatus according to any one of the first to third aspects is mainly used. Features.

In the image forming apparatus of the present invention, the layer thickness regulating member is provided with a pressure detecting member made of a piezoelectric element or the like, and the pressure of the developer at the layer thickness regulating portion is detected and the pressure detection result by the pressure detecting member is used. Since the developer pumping amount is controlled in the developer supply section, the supply of the developer in the longitudinal direction, fluctuations in pumping, especially fluctuations in the usage environment, deterioration of the developer due to repeated use, toner concentration fluctuations, etc. Even if the bulkiness and fluidity change occur, image density unevenness (variation) can be prevented.
In the image forming apparatus of the present invention, since the pressure detection member is appropriately arranged in the longitudinal direction, it is caused by supply in the longitudinal direction, fluctuations in pumping, especially fluctuations in usage environment, deterioration of developer due to repeated use, toner density fluctuations, and the like. Image density unevenness (variation) can be prevented even if the developer is bulky and fluidity varies.
In the image forming apparatus of the present invention, when the pressure fluctuation in the longitudinal direction due to the pressure detection member occurs, the bulkiness and fluidity of the developer are simply changed. In particular, image density unevenness (variation) can be prevented even when fluctuations in usage environment, developer deterioration due to repeated use, developer bulkiness and fluidity fluctuations due to toner density fluctuations, and the like occur.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a developing device and an image carrier.
A developer (not shown) in the developer container 7 is stirred and conveyed by the first stirring member 3 and the second stirring member 4 and supplied to the developer carrier 2. Further, the developer supplied to the developer carrier 2 is supplied to the image carrier 1 which is a photoconductor. Here, the developer carrier 2 is composed of a cylindrical developing sleeve 2a and a magnet roller 2b disposed therein, and the developing sleeve rotates in the arrow direction c, and the magnet roller 2b holds the developer. A predetermined magnetic field is generated.
The developer (not shown) is pumped up by the magnetic field of the magnet roller 2b in the developer supply part a, and is supplied to the layer thickness regulating part b upstream of the layer thickness regulating member 5 by the rotation of the developing sleeve 2a in the arrow direction c. The The layer thickness regulating member 5 is provided with a pressure detection member 6 for detecting the developer pressure at the layer thickness regulating portion b. As the pressure detection member 6, the well-known technique described in the above-mentioned Patent Document 1 can be adopted. That is, for example, a piezoelectric detecting means using a piezoelectric material (crystal or other piezoelectric element) that converts pressure into an electric signal is used.
Based on the pressure detection result of the pressure detection member 6, the developer pumping amount in the developer supply section a is controlled and changed by a pumping amount control means (not shown) to prevent uneven developer pumping (fluctuation).
That is, the present invention includes an agitating member 3 that agitates and conveys a developer composed of toner and a carrier, a developer carrier 2 that holds the developer conveyed by the agitating member 3 in a layer form, and a developer carrier. A layer thickness regulating member 5 for making the thickness of the developer layer uniform, and developing the electrostatic latent image on the image carrier 1 disposed opposite to the developer carrier 2 with toner attached thereto. In an image forming apparatus having a developing device, a pressure detecting means 6 for detecting a pressure applied to the layer thickness regulating member 5 and an amount of developer pumped up by the developer carrier based on a detection result of the pressure detecting means 6 are illustrated. The pumping amount control means that does not perform is characteristic. This pumping amount control means is included, for example, in the control unit of the image forming apparatus main body.

As shown in FIG. 2, a plurality of pressure detection members 6 are arranged at predetermined intervals in the longitudinal direction, which is the rotational axis direction of the developing sleeve 2a. Although not shown, the detection result of the pressure detection member 6 is fed back to the control unit of the image forming apparatus, whereby the longitudinal pressure fluctuation (unevenness) of the developer applied to the pressure detection member 6 is detected and determined.
As a result, even if there are fluctuations in the longitudinal direction, fluctuations in pumping, especially fluctuations in the usage environment, deterioration of the developer due to repeated use, bulkiness of the developer due to fluctuations in the toner density, fluctuations in fluidity, etc., image density unevenness (fluctuation) will occur. To prevent.
The predetermined interval of the pressure detection member 6 is set to be equal to or less than the spiral interval P of the first stirring member 3. FIG. 3 shows an embodiment thereof, which shows the layer thickness regulating member 5, the pressure detecting member 6, and the first stirring member 3. An interval in the longitudinal direction of the pressure detection member 6 is set to be equal to or less than a spiral interval P of the first stirring member 3. For example, as shown in FIG. 3, if the interval between the pressure detection members 6 is P2, P2 is set so that P> P2.
The pumping amount control means will be described. The first stirring member 3 is connected and rotated by a driving device (not shown). The second stirring member 4 is connected to the first stirring member 3 by a gear or the like. From the detection result of the pressure detection means 6, the rotational speed by the drive device is changed from a predetermined value set in advance.
For example, the fluctuation of the bulkiness due to the decrease in the bulkiness of the developer is caused by slowing the reflux speed of the developer by making the rotation speed of the first stirring member 3 slower than a predetermined value set in advance. The developer supply unit a makes it easy to draw up the developer, and prevents fluctuations in the longitudinal direction. Here, the first stirring member 3 and the second stirring member 4 may be connected as described above, or may be driven independently.
Further, as the pumping amount control means, it is possible to change the bulk of the developer by changing the amount of the developer between a developer storage container (not shown) and the developer container 7.

1 is a configuration diagram of a developing device and an image carrier according to the present invention. FIG. 6 is a state explanatory diagram for explaining a state in which a plurality of pressure detection members according to the present invention are arranged at predetermined intervals on the developing sleeve. It is explanatory drawing which made the arrangement | positioning space | interval of the pressure detection member based on this invention below the spiral space | interval of a 1st stirring member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developer carrier 2a Developing sleeve 2b Magnet roller 3 First stirring member 4 Second stirring member 5 Layer thickness regulating member 6 Pressure detection member 7 Developer container

Claims (5)

  A stirrer that stirs and transports the developer composed of toner and carrier, a developer carrier that holds the developer transported by the stirrer in layers, and a uniform developer layer thickness on the developer carrier An image forming apparatus having a developing device for developing toner by attaching toner to an electrostatic latent image on an image carrier disposed opposite to the developer carrier. A pressure detection unit that detects pressure applied to the regulating member, and a pumping amount control unit that controls a pumping amount of the developer pumped up by the developer carrier based on a detection result of the pressure detection unit. Image forming apparatus.   2. The image forming apparatus according to claim 1, wherein the pressure detecting means are arranged at predetermined intervals in the axial direction of the developer carrier.   3. The image forming apparatus according to claim 2, wherein the arrangement interval of the pressure detection means is equal to or less than the spiral interval of the stirring member.   The image forming apparatus according to claim 1, wherein the pumping amount control unit is a pumping amount control unit that changes a rotation speed of the stirring member.   4. The image forming apparatus according to claim 1, wherein the pumping amount control means is a pumping amount control means for changing a developer amount in the developing device.

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