JP2008122808A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive developing device capable of properly disentangling the aggregation of toner, with a simple and easy structure. <P>SOLUTION: An agitator 5 is configured so that stirring portions 52 consisting of a U-shaped pipe are connected at both end portions 53 of the stirring portions 52 on both sides, around a rotating shaft 51 and rotated in the direction of an arrow D in accordance with the rotation of the rotating shaft 51, to send out toner T around the stirring portions 52 to the vicinity of a supply roller 3, while stirring the toner T. In the stirring portions 52, air ejection holes 54 are formed at predetermined intervals, compressed air supplied through the rotating shaft 51 being hollow is ejected from the air ejection holes 54 of the stirring portions 52 connected through the rotating shaft 51 and both end portions 53, to disentangle the aggregation of the aggregated toner T, and air is passed between the toners to improve the flowability of the toner. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device used in an image forming apparatus such as a printer, a copying machine, and a facsimile, and more particularly to a developing device using a non-magnetic one-component toner.

2. Description of the Related Art Conventionally, developing devices using non-magnetic one-component toner that uses a non-magnetic toner such as cyan, yellow, magenta, and black to obtain an image by a one-component developing method are known. In such a non-magnetic one-component toner developing device, as a means for supplying and developing non-magnetic toner on the surface of the developing roller, a toner supply roller such as a rubber roller or a sponge roller is in contact with the developing roller, Non-magnetic toner is supplied from the supply roller to the surface of the developing roller and conveyed, and the thickness of the toner layer on the surface of the developing roller is regulated using a blade to supply a predetermined amount of toner to the photoreceptor. . In this case, in order to satisfactorily supply the toner from the supply roller to the developing roller, the fluidity is enhanced by the action of fine particles for imparting lubricity such as silica added to the toner. ing.
However, in the initial stage, the fluidity of the toner is maintained, but as time passes,
The fluidity decreases as the silica is detached from the toner surface or buried in the toner itself. In a non-magnetic one-component toner developing device, the non-magnetic one-component toner stored in the developing device loses its fluidity in order to always maintain graininess, gradation, density uniformity, etc. Ideally, the toner cohesion is increased for the reasons described above, and the degree of deterioration is steadily decreasing.
In order to unravel the toner aggregation, a piezoelectric element is used as a means for supplying the toner to the developing roller, an alternating voltage is applied to the piezoelectric element to generate vibration, and this vibration causes toner aggregation. It has been proposed to supply toner with good fluidity to the developing roller while solving (see, for example, Patent Document 1).
JP 10-319699 A

However, in the device described in Patent Document 1, since a piezoelectric element is used to solve toner aggregation, securing a high voltage for operating the piezoelectric element and complicating the developing device are caused, leading to an increase in cost. There is a problem.
The present invention has been made in consideration of the above circumstances, and an object thereof is to provide an inexpensive developing device that can appropriately solve toner aggregation with a simple structure.

In order to solve the above-described problems, the invention described in claim 1 includes a developing roller that carries a non-magnetic one-component toner and supplies the toner to a photoconductor, and a supply roller that supplies the toner to the developing roller. The developing device includes an agitator that rotates in a toner hopper that accommodates the toner and conveys the toner in the toner hopper to the supply roller. The agitator includes a rotation agitation unit that conveys the toner to the supply roller and the agitation unit And aggregating release means for releasing aggregation of the toner attached to the unit.
According to a second aspect of the present invention, in the developing device according to the first aspect, the agglomeration releasing means is a wind pressure ejected from an air ejection hole formed in a stirring portion of the agitator.

According to a third aspect of the present invention, in the developing device according to the first or second aspect, the aggregation release means is a fur brush attached to a stirring portion of the agitator.
According to a fourth aspect of the present invention, in the developing device according to any one of the first to third aspects, the aggregation releasing means is a mesh member attached to a stirring portion of the agitator.
According to a fifth aspect of the present invention, in the developing device according to any one of the first to fourth aspects, the toner conveying rotation operation to the supply roller by the agitator is performed for a predetermined time together with the start of power supply to the image forming apparatus. Control means for performing control is provided.
According to a sixth aspect of the present invention, in the developing device according to any one of the first to fifth aspects, the toner conveying and rotating operation to the supply roller by the agitator is performed when the image forming apparatus is returned from the standby state. Control means for performing control for a predetermined time is provided.

  According to the present invention, by adopting the above-described configuration, it is possible to provide an inexpensive developing device that can appropriately solve toner aggregation with a simple structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a developing device according to an embodiment of the present invention. The developing device according to this embodiment includes a developing case 6 that stores toner T, which is a non-magnetic one-component toner. The toner T in this embodiment is a negatively chargeable nonmagnetic toner containing a pigment of any of the colors yellow, magenta, cyan, and black and externally added with anhydrous silica. In the developing case 6, a developing roller 2 for supplying a predetermined amount of toner T to the surface of the photosensitive drum 1 rotating in the direction of arrow A is attached so as to rotate in the direction of arrow B.
The developing roller 2 coats the surface of the SUS mandrel with a resin so as to give a predetermined polarity by friction with the toner T. Here, a negative electrostatic latent image charge is formed on the photosensitive drum 1, and reversal development is performed. Accordingly, a resin is selected so as to give a negatively charged charge to the toner T on the surface of the developing roller 2 and to form a uniform toner thin layer (not shown) on the surface of the developing roller 2. Has been. A developing blade 4 as a toner amount regulating member is in contact with the surface of the developing roller 2, and the toner T on the developing roller 2 is regulated to form a thin toner layer. The amount of toner conveyed to a position opposite to the head is defined.

The developing roller 2 is in contact with a supply roller 3 having an elastic sponge layer on the outer periphery, and the supply roller 3 is rotated in the direction of arrow C. Accordingly, the supply roller 3 and the developing roller 2 are rotationally driven so as to move in the opposite directions at the contact portion 7. For this purpose, the toner T conveyed to the contact portion 7 between the supply roller 3 and the developing roller 2 is rubbed between the supply roller 3 and the developing roller 2 and charged to a predetermined charge amount. It adheres electrostatically to the surface.
On the other hand, an agitator 5 is provided in the developing case 6, and the agitator 5 is rotationally driven in the direction of arrow D, and sends the toner T to the vicinity of the supply roller 3 while stirring the toner T in the developing case 6. Working. As shown in FIG. 2, the agitator 5 has a stirrer 52 composed of a U-shaped pipe on both sides with a rotating shaft 51 as a center, and is connected at both ends 53. The part 52 is rotated in the direction of the arrow D so that the toner T around the stirring part 52 is sent out to the vicinity of the supply roller 3 while stirring. In addition, air stirring holes 52 are formed in the stirring unit 52 at predetermined intervals, and the compressed air supplied through the hollow rotating shaft 51 is connected to the rotating shaft 51 through both end portions 53. It is possible to eject from 52 air ejection holes 54. Accordingly, the compressed air ejected from the air ejection holes 54 is blown to the toner T present around the agitating portion 52, and the aggregation of the aggregated toner T is released, and the air flows between the toners to flow the toner. Improve sexiness. Therefore, when the agitator 5 rotates and transports and supplies the toner T to the supply roller 3, the toner T with good fluidity that has been freed from aggregation of the toner is transported and supplied to the supply roller 3. .

  The ejection of air from the air ejection holes 54 is performed with the rotation of the agitator 5, but the agitator 5 does not need to be constantly rotated and rotates according to the remaining amount of toner in the developing case 6. Can be. Further, it is conceivable that the toner T agglomerates while the image forming apparatus that creates a toner image through a predetermined process by rotating the photosensitive drum 1 is stopped. In particular, the power of the image forming apparatus is turned off. When the operation is stopped from the night when the use is finished until the next morning when the use is started and the toner T in the developing case 6 is left unattended, it is the time when toner aggregation is most likely to occur. The toner T in the developing case 6 sinks with time, and reaches the state where the filling rate becomes as high as 60 to 70% in the next morning. When the toner is used in such a state as it is, it is difficult to form a good image because the fluidity of the toner T is lowered. Therefore, it is necessary to rotate (pre-rotate) the agitator 6 before starting image formation until fluidity suitable for image formation is obtained. However, the conventional agitator takes time. Even if the image forming apparatus is optimized during the process control at the start of image formation by supplying power to the image forming apparatus in the next morning, the process control with the toner having insufficient fluidity is performed by developing bias and gradation. Insufficient results are obtained. Ideally, fluidity is optimized quickly before process control. Therefore, in this embodiment, the agitator 6 is pre-rotated (about 1 minute) from the time when the power supply to the image forming apparatus is turned on until the process control is turned on to ensure the fluidity of the toner. It is controlled by the control device.

  Further, the waiting time of the image forming apparatus is also the time for the toner aggregation to proceed. Accordingly, the counting is started from the time when the image forming apparatus enters the standby mode. When the image forming apparatus is operated again, the necessary rotation time of the agitator 5 is calculated from the stop time during this time, and the pre-rotation is performed. In this case, although not so much when the power of the image forming apparatus is turned off, the toner sinks and agglomerates with time, so that the pre-rotation is similarly performed before the image forming operation by the image forming apparatus is started. Let the agitator 5 do this. However, in this case, pre-rotation corresponding to the stop time is performed for a short time stop, not for a long time. It has been found that the relationship between the stop time and the pre-rotation time has a relationship as shown in FIG. 4 in this embodiment. That is, when the operation is stopped for approximately 2 hours or more, toner aggregation progresses to the same level as when left overnight, and a pre-rotation of 1 minute is required. It was found that image formation can be prepared with pre-rotation of less than 1 minute. Therefore, the stop time from the time when the standby mode is entered until the operation is resumed is automatically measured, and the pre-rotation time shown in FIG. 4 is calculated from the measured stop time so that the pre-rotation of the agitator 5 is performed. By doing so, it is possible to provide a good image using the toner T having good fluidity even immediately after rising.

  FIG. 5 is a block circuit diagram of an embodiment of a control device for controlling the rotational operation of the agitator 5 as described above. 10 is a control circuit, 11 is an agitator drive circuit, 12 is an image forming circuit, and 13 is an image forming start. The stop detection circuit 14 is a power switch for the image forming apparatus. As described above, the control device operates the drive circuit of the agitator 5 by turning the power switch 14 of the image forming apparatus ON and OFF, and controls the pre-rotation time of the agitator 5 by the control circuit. . In addition, the image forming circuit is operated by a signal from the image forming start / stop detection circuit, and the stop time from the stop time to the start time is measured as described above, and the pre-setting of the agitator 5 according to the stop time is measured. The rotation time is controlled by a control circuit. By providing such a control device, it is possible to always supply the toner with good fluidity, which is free from toner aggregation, to the supply roller 3 and the developing roller 2 appropriately, thereby providing a good image. It becomes possible.

As described above, in the present embodiment, the air agitator 52 that supplies the toner T to the supply roller 3 as the agitator 5 is formed with the air ejection holes for releasing the aggregation of the toner aggregates. When the toner T is transported, it is possible to supply the toner to the supply roller 3 as a toner having good fluidity while solving the toner aggregation in which the toner aggregation occurs over time and the fluidity is lowered, thereby providing a good image. It becomes possible.
In this embodiment, a U-shaped stirrer is connected to both sides of the rotating shaft 51 as the rotating stirrer 52. However, the rotating stirrer 52 is not necessarily both sides (both wings) of the rotating shaft 51, but only one side (one winged). It is good.

  FIG. 6 is a diagram showing a schematic configuration of an agitator 5 according to another embodiment of the present invention. In this embodiment, the agitator 5 of the developing device in the first embodiment is changed to another structure. That is, in this embodiment, a U-shaped support rod 56 is connected to the central solid rotation shaft 55 at both ends 57 thereof, and a fur brush 58 is connected to a portion 56a parallel to the rotation shaft 55 of the support rod 56. It is attached by winding. In the first embodiment, the air ejection hole 54 is formed in the stirring portion 52 and the toner aggregation is solved by the wind pressure blown out from the air ejection hole 54. However, in this embodiment, the rotation shaft of the support rod 56 is rotated. The toner T is agitated by the fur brush 58 attached to the portion 56 a parallel to the roller 55 and is transported to the vicinity of the supply roller 3. At the same time, the aggregation of the toner existing around the fur brush 58 is converted into the rotational force of the agitator 5. This improves the fluidity of the toner. In this case, the fur brush 58 may be rotated on the support bar 58. However, if the fur brush 58 is not rotated, the frictional force against the toner T is increased and the toner aggregation is favorably solved. Also in this example, the fur brush 58 may be attached to the rotating shaft 55 in a single wing shape instead of a double wing shape.

Further, as in the case of the first embodiment, the rotary shaft 55 and the support rod 56 are a hollow rotary shaft 51 and a hollow support tube, and an air ejection hole 54 is formed in the support tube. A fur brush may be wound so that the toner aggregation caused by the air ejection holes is removed and the toner aggregation caused by the fur brush 58 is eliminated.
Further, by using the agitator 5 according to the present embodiment and the control device shown in FIG. 5 described above, the pre-rotation operation of the agitator 5 when the power to the image forming apparatus is turned on and when the image forming apparatus is restarted from the standby mode is controlled. It is also possible to do.

FIG. 7 is a diagram showing a schematic configuration of an agitator 5 according to another embodiment of the present invention. In this embodiment, the structure of the agitator 5 in the second embodiment is changed. That is, a U-shaped support rod 56 is connected to the rotating shaft 55 at both ends 57 thereof, and a lattice-like mesh member 59 is attached between the support rod 56 and the rotating shaft 55. When the agitator 5 is rotated and the toner T is conveyed to the supply roller 3 while stirring, the mesh of the mesh member 59 breaks up the aggregation of the toner T, and good fluidity can be imparted to the toner. In this case, if the mesh is too small, the mesh is likely to be clogged. Therefore, the mesh is preferably 1 to 10 mm square, preferably 5 mm square. Also in this example, the mesh member 59 may be attached to the rotating shaft 55 in a single wing shape instead of a double wing shape.
Further, as in the case of the first embodiment, the rotary shaft 55 and the support rod 56 are a hollow rotary shaft 51 and a hollow support tube, and an air ejection hole 54 is formed in the support tube to rotate with the support tube. A mesh member is attached between the shaft and the toner aggregation caused by the air ejection holes and the toner aggregation caused by the mesh member 59 are used together, or the toner aggregation caused by the fur brush 58 of the second embodiment is solved. You may make it use together.
Further, by using the agitator 5 according to the present embodiment and the control device shown in FIG. 5 described above, the pre-rotation operation of the agitator 5 when the power to the image forming apparatus is turned on and when the image forming apparatus is restarted from the standby mode is controlled. It is also possible to do.

It is sectional drawing which shows schematic structure of the image development apparatus of Example 1 by this invention. It is a top view of the agitator used with the image development apparatus of Example 1 by this invention. It is sectional drawing cut | disconnected on the AA line of FIG. It is a figure which shows the relationship between the pre-rotation time of the agitator used with the image development apparatus of Example 1 by this invention, and the stop time of an image forming apparatus with a graph. FIG. 2 is a block circuit diagram of a control device used in the developing device of Example 1 according to the present invention. It is a top view of the agitator of Example 2 by the present invention. It is a top view of the agitator of Example 3 by the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Photosensitive drum, 2 Developing roller, 3 Supply roller, 4 Blade, 5 Agitator, 6 Developing case, 10 Control circuit, 11 Agitator drive circuit, 12 Image forming circuit, 13 Image formation start, stop detection circuit, 14 Power switch, 51, 55 Rotating shaft, 52 Stirrer, 53, 57 Both ends, 54 Air ejection hole, 56 Support rod, 58 Fur brush, 59 Mesh member, T toner

Claims (6)

A developing roller that carries non-magnetic one-component toner and supplies the toner to the photoconductor, a supply roller that supplies the toner to the developing roller, and a toner hopper that stores the toner, and rotates the toner in the toner hopper. In a developing device including an agitator that is conveyed to the supply roller,
2. The developing device according to claim 1, wherein the agitator includes a rotary agitation unit that conveys the toner to the supply roller and an aggregation release unit that is attached to the agitation unit and releases aggregation of the toner. The developing device according to claim 1,
The developing device according to claim 1, wherein the aggregating release means is a wind pressure ejected from an air ejection hole formed in a stirring portion of the agitator. The developing device according to claim 1 or 2,
The developing device according to claim 1, wherein the aggregation release unit is a fur brush attached to a stirring portion of the agitator. In the developing device according to any one of claims 1 to 3,
The developing device according to claim 1, wherein the agglomeration releasing means is a mesh member attached to a stirring portion of the agitator. The developing device according to any one of claims 1 to 4,
A developing device, comprising: a control unit configured to control the toner rotation operation of the toner to the supply roller by the agitator so as to be performed for a predetermined time together with the start of power supply to the image forming apparatus. The developing device according to any one of claims 1 to 5,
A developing device comprising: control means for controlling the rotation of the toner to the supply roller by the agitator so as to be performed for a predetermined time when the image forming apparatus returns from the standby state.

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