JP2006220817A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of preventing a fluctuation in T/C ratio to be detected before and behind exchange of a developing device and preventing an image density adjustment defect. <P>SOLUTION: The developing device includes a developing sleeve rotatably supported to serve as a developer carrier, a developing chamber screw rotatably supported adjacently to the developing sleeve and having a spiral surface in the central axis direction of the rotation, an agitating chamber screw rotatably supported adjacently to the developing screw and having a spiral surface in the central axis direction of the rotation, a developing chamber holding the developing chamber screw, an agitating chamber holding the agitating chamber screw, and a developing container formed with a developer replenishing port on the upperside of agitating chamber. A portion of the agitating chamber and a portion of the agitating screw are supported by an image forming apparatus main body. The developing device is attachable and detachable except a portion of the agitating chamber and a portion of the agitating screw which are made to remain in the image forming apparatus body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device provided in an image forming apparatus such as a copying machine or a laser beam printer (LBP) that forms an image on a sheet material.

  7 and 8 show a conventional example of the present invention.

  Conventionally, in this type of image forming apparatus, a dry developer as a developer is carried on the surface of the developer carrying member, and the developer is conveyed and supplied near the surface of the image carrying member carrying the electrostatic latent image. A method for developing and developing an electrostatic latent image while applying an alternating (alternate) electric field between an image carrier and a developer carrier is well known.

  The developer carrier is generally referred to as a “development sleeve” in the following description because a developing sleeve is often used. The image carrier is generally referred to as a photosensitive drum, and thus the following description. In this case, it is referred to as “photosensitive drum”.

  As a developing method, conventionally, for example, a developer (two-component developer) composed of a two-component composition (carrier particles and toner particles) is used, and a magnetic brush is formed on the surface of a developing sleeve in which a magnet is disposed. The magnetic brush is rubbed or brought close to the opposing photosensitive drum while holding the developing gap, and an alternating electric field is continuously applied between the developing sleeve and the photosensitive drum (between SD) to develop toner particles. There is known a so-called magnetic brush development method in which development is performed by repeatedly performing transition and reverse transition from the sleeve side to the photosensitive drum side (see, for example, Patent Documents 1 and 2).

  The developing device for developing the two-component magnetic brush is configured as shown in FIGS. 7 is a cross-sectional view of a conventional developing device, and FIG. 8 is a plan view. In the figure, 101 is a developing sleeve, 102 is a magnet roller fixedly arranged in the developing sleeve 101, 103 is a developing chamber screw, and 104 is stirring. The chamber screw, 105 is a developing container, 105a is a toner supply port, 105b is a developing chamber, 105c is a stirring chamber, 106 is a regulating blade arranged to form a thin layer of developer on the surface of the developing sleeve 101, 107 is A toner container 108 for storing toner is a supply screw for supplying toner from the toner container 107 to the developing device. As shown in the figure, the developing sleeve 101 is disposed close to the photosensitive drum 109, rotates in the opposite direction or the same direction as the photosensitive drum 109, and is developed in a state where the developer (shown by hatching) is in contact with the photosensitive drum 109. It is set to be possible.

  Developer container 105 contains a developer in which toner particles and magnetic carrier are mixed, and the mixing ratio of toner particles and magnetic carrier (hereinafter referred to as T / C ratio) is the toner consumed by development. The amount of toner corresponding to the above is replenished by the replenishing screw 108 from the toner container 107 containing the replenishing toner. Then, the replenished developer passes through the replenishing port 105a of the developing container 105 and is dropped and replenished to the stirring chamber provided with the stirring chamber screw 104, so that the T / C ratio is kept constant. Various methods have been proposed for detecting and maintaining the mixing ratio of the toner particles and the magnetic carrier in the developing container 105 at this time.

  For example, a detecting means is provided around the photosensitive drum, and light is applied to the toner transferred from the developing sleeve side to the photosensitive drum side, and the T / C ratio is maintained by adjusting the toner replenishment amount from the transmitted light and reflected light at this time. A method for detecting the T / C ratio from reflected light when light is applied to the developer applied on the developing sleeve, a sensor in the developing container, A method of detecting a change in the apparent magnetic permeability μ of a developer in a fixed volume near the sensor by using an inductance and detecting a T / C ratio (hereinafter referred to as a toner concentration detection sensor) has been proposed and put into practical use. ing.

  The toner concentration detection sensor using the change in the magnetic permeability of the developer means that, for example, when the magnetic permeability is increased, the T / C ratio in the developer is lowered at a constant volume, which means that the developer When the toner replenishment is started to mean that the amount of toner in the toner has decreased. On the contrary, when the magnetic permeability decreases, it means that the T / C ratio in the developer has increased within a certain volume. The T / C ratio is controlled based on a sequence in which toner supply is stopped in order to mean that the amount of toner in the developer has increased.

  On the other hand, as shown in FIG. 8, the developing sleeve 102, the developing chamber screw 103, and the agitating chamber screw 104 are rotationally driven from a driving source such as a motor (not shown) through a driving transmission means such as a gear train in a predetermined direction. By rotating at a predetermined speed, the developer in the developer container 105 circulates in the direction of the arrow shown in the figure. What is indicated by the grid lines is the position of the toner supply port 105a. The new toner replenished from the replenishing port 105a is uniformly agitated with the developer while being conveyed through the length A of the agitating chamber, and is sufficiently charged with friction and circulated to the developing chamber. In the developing chamber, a magnetic brush of developer is formed by the developing magnetic field formed by the magnet roller 102, and the toner adhering to the magnetic brush and the toner adhering to the surface of the developing sleeve 102 are formed on the photosensitive drum 109. Development is performed by transferring to the image area of the electrostatic latent image.

JP-A-55-032060 JP 59-165082 A

  However, the conventional example has the following problems.

  That is, in the method using an inductance sensor in the above T / C ratio detection method, when the developing device needs to be replaced due to the life of the developing device or the like, the toner concentration detection sensor is expensive. If it cannot be removed, running costs will increase.

  In addition, the method of removing the toner density detection sensor provided in the developing device from the old developing device and attaching it to the new developing device only when the developing device is replaced is difficult to detect because the position reproducibility is difficult due to variations in parts accuracy. There is a possibility that the T / C ratio fluctuates and density adjustment failure due to detection failure occurs.

  Further, when the toner density detection sensor is provided in the image forming apparatus main body and T / C ratio detection is performed from the outside of the developing device, the detected T / C ratio varies depending on the positioning accuracy of the developing device and the toner density detection sensor. There is a possibility that a density adjustment failure due to a detection failure may occur.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and the object of the present invention is to develop a developing device that can prevent fluctuations in the T / C ratio detected before and after replacement of the developing device and prevent poor image density adjustment. Is to provide.

  To achieve the above object, the present invention provides a developing sleeve that is rotatably supported and serves as a developer carrier, and a developing chamber screw that is rotatably supported adjacent to the developing sleeve and has a spiral surface in the direction of the rotation center axis. A stirring chamber screw that is rotatably supported adjacent to the developing screw and has a spiral surface in the direction of the rotation center axis, a developing chamber that holds the developing chamber screw, and a stirring chamber that holds the stirring chamber screw; In the developing device including a developing container in which a developer supply port is formed above the stirring chamber, an image forming apparatus main body supports a part of the stirring chamber and a part of the stirring screw. A part of the agitation chamber and a part of the agitation screw may be attached and detached while leaving the main body of the image forming apparatus. Further, a toner concentration detection sensor is provided in a part of the stirring chamber.

  When the central axis of the developing chamber screw is horizontal, the central axis of the agitating chamber screw is inclined so as to rise in the direction in which the spiral surface advances when the agitating chamber screw rotates. A toner shutter is provided between a part of the stirring chamber remaining in the chamber and the stirring chamber of the developing device.

  According to the present invention, since the reproducibility of the positional accuracy of the toner density detection sensor with respect to the toner in the developing device can be ensured, fluctuations in the T / C ratio detected before and after replacement of the developing device can be prevented, and poor image density adjustment can be achieved. Can be prevented. Furthermore, since the toner density detection sensor can be left in the main body of the image forming apparatus, the cost of the developing device can be reduced and the running cost can be kept low.

  In addition to the above advantages, it is possible to prevent toner scattering and the like when replacing the developing device, and to improve the workability of replacing the developing device.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
1 and 2 are top views of the developing device according to the first embodiment of the present invention, in which 1 is a developing sleeve, 3 is a developing chamber screw, 4 is a stirring chamber screw, and 5 is a developing container. The inside of the developing container 5 is divided into a developing chamber 5b and a stirring chamber 5c, and 5d is a partition wall. An amount of toner commensurate with the toner consumed by development is dropped and replenished from the replenishing port 5a provided in the upper part of the agitating chamber 5c into the agitating chamber 5c by the action of a replenishing screw 8 (not shown).

  In the agitating chamber 5c, the toner and the developer are agitated and frictionally charged by the action of the agitating chamber screw 4, and the developer circulates in the developing container 5 by the action of the developing chamber screw 3 in the developing chamber 5b. The electrostatic latent image on the photosensitive drum is developed by the formed magnetic brush as in the conventional example. The arrows in the figure indicate the developer circulation direction.

  The stirring chamber 5c is divided into a first stirring chamber 5c1, a second stirring chamber 5c2, and a third stirring chamber 5c3. The first stirring chamber 5c1 and the third stirring chamber 5c3 are a developing device, and the second stirring chamber 5c2 is an image forming unit. Are respectively fixed to the sex device main body 13. The second stirring chamber 5c2 is provided with a toner concentration detection sensor 14 for detecting a change in the apparent permeability μ of the developer in a certain volume near the sensor by using the inductance of the coil and detecting the T / C ratio. Yes.

  The agitation screw 4 is divided into a first agitation screw 4a, a second agitation screw 4b, and a third agitation screw 4c. The first agitation screw 4a and the third agitation screw 4c are connected to the developing device, and the second agitation screw 4b is Each of the second stirring chambers 5c2 is rotatably supported. When the developing device is set in the main body of the image forming apparatus, the first stirring screw 4a, the second stirring screw 4b, and the third stirring screw 4c are connected by a coupling (not shown), and both perform toner stirring.

  Now, the developing device is moved in the direction of arrow A and taken out from the image forming device main body. At this time, as shown in FIG. 2, both the second stirring chamber 5 c 2 and the second stirring screw 4 b remain in the image forming apparatus main body 13. The toner concentration detection sensor 14 supported in the second stirring chamber 5c2 also remains in the image forming apparatus main body 13. Thereafter, a new developing device is set in the image forming apparatus main body. At this time, the positional relationship among the second stirring chamber 5c2, the second stirring screw 4b, and the toner concentration detection sensor 14 does not change before and after the replacement of the developing device. Therefore, the reproducibility of the positional accuracy with respect to the toner in the developing device of the toner density detection sensor can be ensured, the fluctuation of the detected T / C ratio before and after replacement of the developing device can be prevented, and the poor image density adjustment can be prevented. . Furthermore, since the toner density detection sensor can be left in the main body of the image forming apparatus, the cost of the developing device can be reduced and the running cost can be kept low.

<Embodiment 2>
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 3 is a top view of the developing device according to Embodiment 2 of the present invention, FIG. 4 is a side view of the developing device, FIG. 5 is a top view of the developing device, and FIG. 6 is a side view of the developing device. Since the present embodiment has many parts in common with the first embodiment, only characteristic parts will be described.

  As shown in FIG. 4, the first stirring chamber 5c1, the second stirring chamber 5c2, the third stirring chamber 5c3, the first stirring screw 4a, the second stirring screw 4b, and the third stirring screw 4c are connected to the developing sleeve 1 and the developing. The axial direction is inclined as shown in the figure with respect to the axial direction of the chamber screw 3, and the direction of the inclination is a direction in which the developer conveyance direction in the stirring chamber screw is the upward direction. The three stirring chambers are connected to each other through an opening 17 and an opening 18. The shutter 15 is provided in the first stirring chamber 5c1 and the shutter 16 is provided in the second stirring chamber 5c2. The shutter 15 is open when three stirring chambers are connected.

  Now, as shown in FIG. 5, the developing device is moved in the direction of arrow A, and is taken out from the image forming apparatus main body. At this time, both the second stirring chamber 5c2 and the second stirring screw 4b remain in the image forming apparatus main body 13. The toner concentration detection sensor 14 supported in the second stirring chamber 5c2 also remains in the image forming apparatus main body 13.

  The shutter 15 closes the opening 17 and the shutter 16 closes the opening 18 by a link mechanism (not shown). Thereby, in addition to the advantages described in the first embodiment, it is possible to prevent toner scattering and the like when the developing device is replaced, and to improve the workability of replacing the developing device.

FIG. 2 is a top view of the developing device according to the first embodiment of the present invention. FIG. 2 is a top view of the developing device according to the first embodiment of the present invention. FIG. 6 is a top view of a developing device according to a second embodiment of the present invention. It is a side view of the developing device concerning Embodiment 2 of the present invention. FIG. 6 is a top view of a developing device according to a second embodiment of the present invention. It is a side view of the developing device concerning Embodiment 2 of the present invention. It is sectional drawing of the conventional image development apparatus. It is a top view of the conventional developing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing sleeve 3 Developing chamber screw 4a 1st stirring chamber screw 4b 2nd stirring chamber screw 4c 3rd stirring chamber screw 5 Developing container 5c1 1st stirring chamber 5c2 2nd stirring chamber 5c3 3rd stirring chamber 8a Supply screw 14 Toner density detection Sensor

Claims (3)

A developing sleeve that is rotatably supported and serves as a developer carrying member, a developing chamber screw that is rotatably supported adjacent to the developing sleeve and has a spiral surface in the direction of the rotation center axis, and rotatable adjacent to the developing screw A stirring chamber screw having a spiral surface in the direction of the rotation center axis, a developing chamber for holding the developing chamber screw, a stirring chamber for holding the stirring chamber screw, and a developer supply port formed above the stirring chamber In the developing device including the developed developer container,
A part of the stirring chamber and a part of the stirring screw are supported by the main body of the image forming apparatus, and the developing device is attached and detached while leaving a part of the stirring chamber and a part of the stirring screw in the main body of the image forming apparatus. A developing device capable of being used.   The developing device according to claim 1, wherein a toner concentration detection sensor is provided in a part of the stirring chamber.   When the central axis of the developing chamber screw is horizontal, the central axis of the agitating chamber screw is inclined so that the spiral surface of the agitating chamber screw moves upward when the agitating chamber screw rotates, and remains in the image forming apparatus main body. The developing device according to claim 1, wherein a toner shutter is provided between a part of the stirring chamber and the stirring chamber of the developing device.

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