JP2010145808A - Powder conveying method, powder conveying device, developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conveying method and a power conveying device which can improve both of agitation capacity and conveying capacity by conveying powder in the same direction while uniformly agitating the powder by a plurality of conveying members. <P>SOLUTION: In the power conveying method and device for conveying powder such as a developer, the powder conveying device includes a plurality of conveying members 56a, 56b provided with conveying capacity in a longitudinal direction. The plurality of conveying members 56a, 56b are arranged in a vertical direction approximately in parallel and stored in a container to form one conveying path. The conveying directions of the plurality of conveying members 56a, 56b are completely the same direction in the longitudinal direction and the plurality of conveying members 56a, 56b communicate with each other in a half area and more in the conveying member length of the longitudinal direction. Since powder is conveyed while being agitated between the plurality of conveying members 56a, 56b, the power conveying method and device excellent in both the agitation capacity and the conveying capacity can be obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a powder conveying method, a powder conveying apparatus, and a developing device used for a process cartridge and an image forming apparatus, and further includes a process cartridge including the developing device, and the developing device or the process cartridge. The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, a plotter, or a multifunction machine or a digital direct plate-making machine.

A conventional developing device will be described with reference to FIG. In a conventional two-component developing device using a developer composed of a colored powder (hereinafter referred to as toner) and a carrier, the developer in which the toner and the carrier are mixed in the developing container 153 and stirred to an appropriate toner concentration. Is conveyed onto a developing roller 151 as a developer carrying member.
In the example of FIG. 10, the developer G is transported in different directions in the axial direction by the transport screws 155 and 156. The conveying screws 155 and 156 are partitioned by the developing container 153, but there is no partition at both ends in the axial direction, so that the developer can be transferred between the screws. Therefore, the developer repeats circulation between the conveying screws 155 and 156.

Here, after a part of the developer conveyed on the conveying screw 155 adjacent to the developing roller 151 is carried on the developing roller 151 and the developer conveying amount is regulated by the doctor blade 152 as a developer regulating member, The latent image on the image carrier 101 is developed by being guided to a development area which is a re-close area between the developing roller 151 and the image carrier 101.
The developer after the developing operation is separated from the developing roller 151 in the developing container 153 and returned to the conveying path of the conveying screw 155 to repeat the circulation.

In the developing device as described above, unevenness in screw conveyance and image density unevenness due to fluctuations in toner density during conveyance may occur. In particular, when a large amount of toner is replenished by the toner replenishing device, the toner may float on the surface of the developer and be transported as it is to cause density unevenness. In order to prevent this, there is a conventional technique aiming to promote mixing by changing the shape of the screw or the conveyance unit. For example, in the invention described in Patent Document 1, the screw has a spiral shape to promote stirring of the conveyance screw. A part is notched and a standing part for stirring is provided.
However, if the agitating function is increased by changing the shape with one screw, the conveying ability is sacrificed. If the conveying ability is lowered, the developer that consumed the toner and the toner are replenished. It is desirable to improve both the conveying ability and the stirring ability because density unevenness occurs with the developer and causes the image density to fluctuate. The transfer capacity can be improved by increasing the rotation speed of the screw, but in that case, other problems such as heat generation due to high-speed rotation and deterioration of durability due to wear of bearings, etc. occur, so without increasing the rotation speed. A means for improving the conveying ability and stirring ability is necessary.

Japanese Patent Laid-Open No. 2006-178381

For toners and carriers that have become smaller in particle size and increased in fluidity in recent years, the toner tends to float and flow over the screw, so the spiral part of the screw and the stirring promoting part are hidden in the developer. If so, it is difficult to disperse.
In the countermeasure example of Patent Document 1 described above, although there is an action of promoting stirring, the conveying force in the axial direction is reduced. Therefore, the action of stirring the toner that tends to accumulate the developer and floats on the surface of the developer is as follows. weak.
For example, when a powder (developer) mixed with toner and carrier is transported in one direction, the stirring action is weak only with a single transport member, and in particular, toner near the surface is transported without being mixed with other mainstreams. As a result, nonuniform stirring occurs in the powder (developer).

  The present invention has been made in view of the above circumstances, and a powder conveying method capable of improving both the stirring ability and the conveying ability by conveying in the same direction while uniformly stirring using a plurality of conveying members. It is an object of the present invention to provide a powder conveying apparatus and a developing apparatus to which the powder conveying method is applied. Furthermore, the present invention provides a process cartridge that includes the developing device and improves maintainability such as replacement of the developing device, and that includes the developing device and suppresses the occurrence of density unevenness to perform stable image formation. An object of the present invention is to provide an image forming apparatus capable of performing the above.

In order to achieve the above object, the present invention employs the following solutions.
The first means of the present invention is a powder conveying method for conveying powder, and has a plurality of conveying members having conveying ability in the longitudinal direction, and the plurality of conveying members are arranged substantially in parallel in the vertical direction. And a container for accommodating the plurality of transport members to form a single transport path, wherein the transport directions of the plurality of transport members are all the same direction with respect to the longitudinal direction, The members communicate with each other in a region that is more than half of the length of the conveying member in the longitudinal direction.

The second means of the present invention is characterized in that, in the powder conveying method of the first means, among the plurality of conveying members, adjacent conveying members have different conveying speeds in the longitudinal direction.
According to a third means of the present invention, in the powder conveying method of the first or second means, among the plurality of conveying members, the conveying ability of the conveying member positioned below is a vertical component rather than a longitudinal component. Is set to be higher.
According to a fourth means of the present invention, in the powder conveying method of the third means, the conveying member has spiral blades, and the pitch of the blades of the conveying member located below is the upper conveying material. It is set longer than the pitch of the blades of the member.
According to a fifth means of the present invention, in the powder conveying method of any one of the first to fourth means, one or more fins extending substantially horizontally with the longitudinal direction are provided on the surface of the conveying member. It is characterized by that.

According to a sixth means of the present invention, in the powder conveying method of the first means, the conveying member is a screw member having a spiral blade, and an uneven shape is provided on the outer peripheral surface of the spiral blade. And
According to a seventh means of the present invention, in the powder conveying method of the sixth means, the conveying member is a screw member having a spiral blade, and a plurality of groove shapes are provided on the outer peripheral surface of the spiral blade. It is characterized by.

The eighth means of the present invention is characterized in that, in the powder conveying method of the first means, a stirring member is provided between conveying members arranged substantially in parallel in the vertical direction.
According to a ninth means of the present invention, in the powder conveying method of the eighth means, the stirring member is provided with a plurality of protrusions around an axis.

  A tenth means of the present invention is a powder conveying apparatus for conveying powder, and has a plurality of conveying members having conveying ability in the longitudinal direction, and the plurality of conveying members are arranged substantially in parallel in the vertical direction. And a container for accommodating the plurality of transport members to form a single transport path, wherein the transport directions of the plurality of transport members are all the same direction with respect to the longitudinal direction, The members communicate with each other in a region that is more than half of the length of the conveying member in the longitudinal direction.

The eleventh means of the present invention is characterized in that, in the powder conveying apparatus of the tenth means, among the plurality of conveying members, adjacent conveying members have different conveying speeds in the longitudinal direction.
The twelfth means of the present invention is the powder conveying apparatus of the tenth or eleventh means, wherein among the plurality of conveying members, the conveying ability of the conveying member positioned below is a vertical component rather than a longitudinal component. Is set to be higher.
According to a thirteenth means of the present invention, in the powder conveying apparatus of the twelfth means, the conveying member has spiral blades, and the pitch of the blades of the conveying member positioned below is the upper conveying material. It is set longer than the pitch of the blades of the member.
According to a fourteenth means of the present invention, in the powder conveying apparatus according to any one of the tenth to thirteenth means, one or more fins extending substantially horizontally with the longitudinal direction are provided on the surface of the conveying member. It is characterized by that.

According to a fifteenth means of the present invention, in the powder conveying apparatus according to the tenth means, the conveying member is a screw member having a spiral blade, and an uneven shape is provided on an outer peripheral surface of the spiral blade. And
According to a sixteenth means of the present invention, in the powder conveying apparatus of the fifteenth means, the conveying member is a screw member having a spiral blade, and a plurality of groove shapes are provided on the outer peripheral surface of the spiral blade. It is characterized by.

The seventeenth means of the present invention is characterized in that, in the powder conveying apparatus of the tenth means, a stirring member is provided between conveying members arranged substantially in parallel in the vertical direction.
According to an eighteenth means of the present invention, in the powder conveying apparatus of the seventeenth means, the stirring member is provided with a plurality of protrusions around an axis.

  The nineteenth means of the present invention comprises: a developer made of powder; a developer carrier that carries the developer; a supply unit that supplies the developer to the developer carrier; and the supply A developing device that receives the developer from the unit, conveys the developer while stirring, and then returns the developer to the supply unit, and the stirring and conveying unit includes a plurality of conveying capabilities in the longitudinal direction. A plurality of conveying members arranged substantially in parallel in the vertical direction, including a container that accommodates the plurality of conveying members to form one conveying path, and the conveying direction of the plurality of conveying members Are all in the same direction with respect to the longitudinal direction, and the members of the plurality of conveying members communicate with each other in a region that is more than half the length of the conveying member in the longitudinal direction.

The twentieth means of the present invention is characterized in that, in the developing device of the nineteenth means, among the plurality of transport members, adjacent transport members have different transport speeds in the longitudinal direction.
The twenty-first means of the present invention is the developing device of the nineteenth or twentieth means, wherein among the plurality of transport members, the transport capability of the transport member positioned below is higher in the vertical direction component than in the longitudinal direction component. Is set to be high.
According to a twenty-second means of the present invention, in the developing device according to the twenty-first means, the conveying member has a spiral blade, and the pitch of the blade of the conveying member positioned below is the same as that of the upper conveying member. It is characterized by being set longer than the pitch of the blades.
According to a twenty-third means of the present invention, in the developing device according to any one of the nineteenth to twenty-second means, one or more fins extending substantially horizontally with the longitudinal direction are provided on the surface of the conveying member. And

According to a twenty-fourth means of the present invention, in the developing device of the nineteenth means, the conveying member is a screw member having a spiral blade, and an uneven shape is provided on an outer peripheral surface of the spiral blade. .
According to a twenty-fifth means of the present invention, in the developing device of the twenty-fourth means, the conveying member is a screw member having a spiral blade, and a plurality of groove shapes are provided on an outer peripheral surface of the spiral blade. And

A twenty-sixth means of the present invention is characterized in that, in the developing device of the nineteenth means, a stirring member is provided between the conveying members arranged substantially in parallel in the vertical direction.
According to a twenty-seventh means of the present invention, in the developing device of the twenty-sixth means, the stirring member is provided with a plurality of protrusions around an axis.

A twenty-eighth means of the present invention is a process cartridge, wherein the image carrier and the developing device of any one of the nineteenth to twenty-seventh means are integrated.
A twenty-ninth means of the present invention is an image forming apparatus comprising an image carrier and a developing device of any one of the nineteenth to twenty-seventh means.
A thirtieth means of the present invention is an image forming apparatus, characterized in that the process cartridge of the twenty-eighth means is provided.

In the powder conveying method of the first means of the present invention, since a plurality of conveying members are used and the members are communicated with each other to convey the powder while mixing the conveying members, the stirring ability / conveying ability Both can provide an excellent powder conveying method.
In the powder conveying method of the second means, in addition to the effects of the first means, the conveying speed of the conveying members is varied to generate convection at the boundary between the conveying members and improve the stirring ability. it can.
In the powder conveying method of the third means, in addition to the effects of the first or second means, the conveying member positioned below is set so that the conveying ability of the vertical component is high, so that the lower part in the conveying path It is possible to positively stir powders that are difficult to mix.
In the powder conveying method of the fourth means, in addition to the effect of the third means, the conveying member positioned below is set so that the conveying ability of the vertical component is high, so that it is difficult to mix in the lower part of the conveying path. The powder can be actively stirred. Specifically, by increasing the pitch of the spiral blades, it is possible to easily improve the conveyance capability in the vertical direction while maintaining the minimum conveyance capability.
In the powder conveying method of the fifth means, in addition to the effects of any one of the first to fourth means, by providing the conveying member with fins, the powder is actively moved between the conveying members, It can be mixed more uniformly.

In the powder conveying method of the sixth means, in addition to the effects of the first means, by providing an uneven shape on the outer peripheral surface of the spiral blade of the screw member, turbulence occurs between the screw outer periphery and the wall surface, By encouraging convection, it is possible to move and stir powder that is difficult to move near the wall surface.
In the powder conveying method of the seventh means, in addition to the effects of the sixth means, by forming a groove shape, an effect higher than that of minute irregularities can be obtained.

In the powder conveying method of the eighth means, in addition to the effects of the first means, a stirring member for stirring the powder is provided between a plurality of conveying members arranged in the vertical direction. Can be promoted.
In the powder conveying method of the ninth means, in addition to the effect of the eighth means, the stirring member is provided with a plurality of protrusions around the shaft, so that stirring of the powder can be further promoted, It is possible to mix more uniformly.

In the powder conveying apparatus of the tenth means of the present invention, since a plurality of conveying members are used and the members are communicated with each other to convey the powder while mixing the conveying members, the stirring ability and conveying ability In both cases, an excellent powder conveying apparatus can be obtained.
In the powder conveying apparatus of the eleventh means, in addition to the effect of the tenth means, the conveying speed of the conveying members is varied to generate convection at the boundary between the conveying members and improve the stirring ability. it can.
In the powder conveying apparatus of the twelfth means, in addition to the effects of the tenth or twelfth means, the conveying member positioned below is set so that the conveying ability of the vertical component is high, so that the lower part in the conveying path It is possible to positively stir powders that are difficult to mix.
In the powder conveying apparatus of the thirteenth means, in addition to the effects of the twelfth means, the conveying member positioned below is set so that the conveying ability of the vertical component is high, so that it is difficult to mix in the lower part of the conveying path. The powder can be actively stirred. Specifically, by increasing the pitch of the spiral blades, it is possible to easily improve the conveyance capability in the vertical direction while maintaining the minimum conveyance capability.
In the powder conveying device of the fourteenth means, in addition to the effect of any one of the tenth to thirteenth means, the powder is positively moved between the conveying members by providing fins on the conveying member, It can be mixed more uniformly.

In the powder conveyance device of the fifteenth means, in addition to the effect of the tenth means, by providing an uneven shape on the outer peripheral surface of the spiral blade of the screw member, turbulent flow is generated between the screw outer periphery and the wall surface, By encouraging convection, it is possible to move and stir powder that is difficult to move near the wall surface.
In the powder conveying device of the sixteenth means, in addition to the effects of the fifteenth means, the groove shape makes it possible to obtain an effect higher than that of minute irregularities.

In the powder conveying apparatus of the seventeenth means, in addition to the effect of the tenth means, the agitation member for agitating the powder is provided between the conveying members arranged in the vertical direction, so that the agitation of the powder is performed. Can be promoted.
In the powder conveying device of the eighteenth means, in addition to the effect of the seventeenth means, the stirring member is provided with a plurality of protrusions around the shaft, so that stirring of the powder can be further promoted, It is possible to mix more uniformly.

In the developing device of the nineteenth means of the present invention, since a plurality of conveying members are used and the members are communicated with each other, the developer is conveyed while being mixed between the conveying members, so that both the stirring ability and conveying ability are excellent. Development apparatus can be obtained.
In the developing device of the twentieth means, in addition to the effect of the nineteenth means, the conveying speeds of the conveying members are made different so that convection can be generated at the boundary between the conveying members and the stirring ability can be improved.
In the developing device of the twenty-first means, in addition to the effects of the nineteenth or twentieth means, the conveying member positioned below is set so that the conveying ability of the vertical component is high, so that the lower part in the conveying path is mixed. Difficult developers can be actively stirred.
In the developing device of the twenty-second means, in addition to the effect of the twenty-first means, a developer that is difficult to mix in the lower part of the conveying path is set by increasing the conveying ability of the component in the vertical direction of the conveying member located below. Can be actively stirred. Specifically, by increasing the pitch of the spiral blades, it is possible to easily improve the conveyance capability in the vertical direction while maintaining the minimum conveyance capability.
In the developing device of the twenty-third means, in addition to the effect of any one of the nineteenth to twenty-second means, the developer is positively moved between the conveying members by providing fins on the conveying member, so that it is more uniform. Can be mixed.

In the developing device of the twenty-fourth means, in addition to the effect of the nineteenth means, by providing an uneven shape on the outer peripheral surface of the spiral blade of the screw member, turbulent flow is generated between the screw outer periphery and the wall surface, and convection is generated. By urging, the developer that is difficult to move near the wall surface can be moved and stirred.
In the developing device of the twenty-fifth means, in addition to the effect of the twenty-fourth means, by forming a groove shape, an effect higher than that of minute unevenness can be obtained.

In the twenty-sixth developing device, in addition to the effect of the nineteenth means, a stirring member for stirring the developer is provided between a plurality of conveying members arranged in the vertical direction, so that stirring of the developer is promoted. can do.
In the developing device of the twenty-seventh means, in addition to the effect of the twenty-sixth means, the stirring member is provided with a plurality of protrusions around the shaft, so that the stirring of the developer can be further promoted and more uniform. Can be mixed.

In the process cartridge of the twenty-eighth means, since the image carrier and the developing device of any one of the nineteenth to twenty-seventh means are integrated, the attaching / detaching operation to the apparatus main body becomes easy.
In the image forming apparatus of the twenty-ninth means, by providing the developing device of any one of the nineteenth to twenty-seventh means, an image forming apparatus capable of performing stable image formation while suppressing occurrence of density unevenness. Can be obtained.
In the image forming apparatus of the thirtieth means, the process cartridge of the twenty-eighth means is provided, whereby an image forming apparatus with improved image quality and maintainability can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of the configuration of the entire image forming apparatus used in the present invention, and FIG. 2 shows an image forming unit including the basic configuration of the developing device 5. A specific configuration of the developing device 5 will be described in an embodiment described later.

In FIG. 1, reference numeral 100 denotes an apparatus main body, 31 denotes a toner replenishing unit, and 32 denotes a document reading unit.
As shown in FIG. 1, the apparatus main body 100 corresponds to each color (yellow, magenta, cyan, black) so as to face the lower surface of the intermediate transfer belt 8 as an unfixed image carrier of the intermediate transfer unit 10. The image forming units 6Y, 6M, 6C, and 6Bk are arranged in parallel. Since the four image forming units 6Y, 6M, 6C, and 6Bk installed in the apparatus main body 100 have substantially the same structure except for the color of the toner used in the image forming process, the image forming unit in FIG. In the drawing, the alphabets (Y, M, C, Bk) of reference numerals in the section 6, the photosensitive drum 1, and the primary transfer bias roller 9 as the primary transfer unit are omitted.

As shown in FIG. 2, the image forming unit 6 includes a photosensitive drum 1 as an image carrier, a charging unit 4 disposed around the photosensitive drum 1, a developing device 5 as a developing unit, and a cleaning unit 2. (Only the developing device 5 is shown in FIG. 1).
An image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1 of the image forming unit 6 to form a desired toner image on the photosensitive drum 1. .

More specifically, the photosensitive drum 1 is rotationally driven in a clockwise direction in FIG. 2 by a driving unit (not shown), and the surface of the photosensitive drum 1 is uniform at the charging unit 4 by the charging roller 4a. Is charged (charging process).
Thereafter, the surface of the photosensitive drum 1 reaches an irradiation position of a laser beam L emitted from an exposure unit (not shown), and an electrostatic latent image is formed by exposure scanning at this position. At this time, the toner consumption amount is estimated by integrating (pixel counting) the irradiation area of the laser beam.
Thereafter, the surface of the photosensitive drum 1 reaches a position facing the developing device 5, and the electrostatic latent image is developed at this position to form a desired toner image (developing process). In addition, the toner replenishing unit 31 replenishes the developing device 5 with a toner amount corresponding to the previously estimated toner consumption amount. After toner replenishment, the developing device 5 can confirm that the toner density has reached an appropriate toner density by means of the toner density detection means, and can issue an additional toner replenishment command as necessary.

Thereafter, the surface of the photosensitive drum 1 reaches a position facing the intermediate transfer belt 8 and the primary transfer bias roller 9, and the toner image on the photosensitive drum 1 is transferred onto the intermediate transfer belt 8 at this position. (Primary transfer process).
At this time, a small amount of untransferred toner remains on the photosensitive drum 1.
Thereafter, the surface of the photoreceptor 1 reaches a position facing the cleaning unit 2, and untransferred toner remaining on the photoreceptor drum 1 is collected by the cleaning blade 2a at this position (cleaning step). After cleaning, the electric potential of the surface of the photosensitive drum 1 is initialized by the neutralizing roller 11.
Thus, a series of image forming processes performed on the photosensitive drum 1 is completed.

As shown in FIG. 1, the image forming process described above is performed by each of the four image forming units 6Y, 6M, 6C, and 6Bk. That is, a laser beam L based on image information from an exposure unit (optical writing device) (not shown) disposed below the image forming unit is applied to the photosensitive drums of the image forming units 6Y, 6M, 6C, and 6Bk. Irradiated towards. Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 8 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 8.
The four primary transfer bias rollers 9Y, 9M, 9C, and 9Bk respectively sandwich the intermediate transfer belt 8 with the photosensitive drums 1Y, 1M, 1C, and 1Bk to form a primary transfer nip. The primary transfer bias rollers 9Y, 9M, 9C, and 9Bk are applied with a transfer bias having a polarity opposite to the polarity of the toner.
The intermediate transfer belt 8 runs in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 9Y, 9M, 9C, and 9Bk. In this way, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1Bk are primarily transferred while being superimposed on the intermediate transfer belt 8.
Thereafter, the intermediate transfer belt 8 onto which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 19 as a secondary transfer unit. The color toner image formed on the intermediate transfer belt 8 is transferred onto a transfer sheet P as a recording medium conveyed to the secondary transfer nip position. Thus, a series of transfer processes performed on the intermediate transfer belt 8 is completed.

A plurality of transfer sheets P are stored in a paper feeding unit 26 disposed in the lower part of the apparatus main body 100, and are separated and fed one by one by a paper feeding roller 27. The fed transfer paper P is temporarily stopped by the registration roller pair 28, and after the oblique deviation is corrected, it is conveyed toward the secondary transfer nip by the registration roller pair 28 at a predetermined timing. Then, a desired color image is transferred onto the transfer paper P at the secondary transfer nip.
The transfer paper P onto which the color image has been transferred at the position of the secondary transfer nip is conveyed to the fixing unit 20, where the color image transferred to the surface is fixed by heat and pressure generated by the fixing roller and the pressure roller. The
After the fixing, the transfer paper P is discharged as an output image to the paper discharge unit 30 formed on the upper surface of the apparatus main body by the paper discharge roller pair 29 and stacked. Thus, a series of image forming processes in the image forming apparatus is completed.

In the above, an example of the configuration and operation of the image forming apparatus according to the present invention has been described. However, in the image forming apparatus according to the present invention, the configuration of the developing device 5 and the developer composed of powder (for example, toner and carrier) are particularly preferred. It has a feature in the transport method.
As shown in FIG. 2, the developing device 5 according to the present invention includes a developer carrier 51 that carries the developer G, a supply unit 55 that supplies the developer to the developer carrier 51, An agitating and conveying unit 56 for receiving the developer from the unit 55 and conveying the developer while stirring is returned to the supply unit 55.
The agitating and conveying unit 56 is a configuration of the powder conveying apparatus according to the present invention, and includes a plurality of conveying members 56a and 56b having a conveying ability in the longitudinal direction, and the plurality of conveying members 56a and 56b are arranged in the vertical direction. The container 53 is disposed substantially in parallel and contains a plurality of transport members 56a and 56b to form a single transport path. The transport directions of the transport members 56a and 56b are all the same as the longitudinal direction. The members of the plurality of transport members 56a and 56b communicate with each other in a region that is more than half of the length of the transport member in the longitudinal direction.
Hereinafter, specific examples of the developing device and the powder conveying method according to the present invention will be described.

[Example 1]
FIG. 3 is a schematic configuration diagram of a developing device to which the present invention is applied, and FIG. 4 is a schematic explanatory diagram of the conveying unit in the longitudinal direction.
In FIG. 3, the developing device 5 includes a developing roller 51 that is a developer carrying member, a doctor blade 52 that is a developer regulating member, and a supply screw 55 that constitutes a supply unit that supplies the developer to the developing roller 51. An agitating / conveying section (powder conveying apparatus) 56 for receiving the developer from the supply screw 55 and conveying it while stirring with the two agitating / conveying screws 56a and 56b, and a developer container for storing them. 53. Although not shown, the developer container 53 contains a developer composed of, for example, toner and a carrier.

As shown in FIGS. 3 and 4A, a partition wall 54 is provided between the supply screw 55 and the stirring and conveying screws 56a and 56b. , The developer is supplied to the developing roller 51 while transporting the developer in the front direction in FIG. 3 (right direction in FIG. 4A), and also serves to collect the developer after the development operation. ing.
The aforementioned partition wall 54 is eliminated at the front end portion in FIG. 3 (the right end portion in FIG. 4A), and the developer is transferred from the supply screw 55 to the stirring and conveying screws 56a and 56b.
The two agitating / conveying screws 56a and 56b are rotated around the longitudinal axis by a drive unit (not shown), and the developer sent from the supply screw 55 is moved in the rear direction in FIG. 3 (FIG. 4B). The developer is stirred while being conveyed in the left direction.
A toner replenishing port 59 is provided above the agitating and conveying screws 56a and 56b in the middle of conveyance, and new toner is supplied during the conveyance of the developer, and the toner is developed using the two agitating and conveying screws 56a and 56b. It can be quickly conveyed while stirring and mixing into the agent.
Since the aforementioned partition wall 54 is eliminated at the back end portions (the left end portion in FIG. 4B) of the stirring and conveying screws 56a and 56b in FIG. 3, the stirring and conveying screws 56a and 56b are moved to the supply screw 55. The developer is delivered, and thereby the developer circulates in the developing container 53.

The two agitating and conveying screws 56a and 56b both have the ability to convey in the same direction on the back side in the figure, and there is no partition wall across the length between the screws (communication port (slit)) 58 is provided, and the developer can freely move between the screws during the conveyance.
Further, the two agitating and conveying screws 56a and 56b are set so that the conveying speeds in the longitudinal direction are different.
As a specific configuration for making the longitudinal conveying speeds of the two agitating and conveying screws 56a and 56b different, for example, changing the rotational speed of the two agitating and conveying screws 56a and 56b is the most direct. However, it can be dealt with by changing the screw pitch of the two agitating and conveying screws 56a and 56b. Also, a resistance is provided by raising a fin between the screws, a notch is provided in one screw, or a partly outer diameter is provided. It is conceivable to reduce the average transport speed by providing an area that cannot be transported by narrowing the area.
Thus, by making the longitudinal conveying speeds of the two agitating and conveying screws 56a and 56b different, a speed difference with respect to the conveying direction is generated at the boundary portion between the screws, and shear stress is generated, thereby increasing the speed. A flow (vortex) is generated from one side to the other, which greatly improves the mixing action. Note that the same effect can be obtained regardless of which of the two speeds is set faster.

Further, as shown in FIG. 4 (b), the agitating and conveying screws 56a and 56b have a shape in which a rotating blade is provided with a spiral blade, and the conveying surface is inclined with respect to the axis. It is also broken down in the direction perpendicular to the axis. This conveying ability in the vertical direction is a factor that greatly affects the stirring ability of the developer.
In this embodiment, the pitch of the spiral blades of the stirring and conveying screw 56b positioned below is set larger than that of the upper stirring and conveying screw 56a. Increasing the pitch of the spiral blades is synonymous with decreasing the inclination angle of the spiral blades with respect to the rotation axis, thereby increasing the vertical component of the transport capability.
In addition, as a specific means for strengthening the vertical component of the conveying capacity in the lower agitating and conveying screw 56b,
The relationship between the screw pitch (P) and the screw outer diameter (D) is P> 2D.
-The inclination angle of the screw conveying surface is 45 ° or less with respect to the axial direction.
-As will be described later in Example 2, fins are provided on the screw conveying surface (the fins may not be horizontal, and may have a reverse spiral shape as provided at the end of the screw).
and so on.
As described above, by setting the pitch of the spiral blades of the stirring and conveying screw 56b positioned below to be larger than that of the upper stirring and conveying screw 56a, the developer is positively applied from below to the stirring and conveying screw 56a. It is possible to move. In addition, since it falls from above to below due to gravity, the vertical movement of the developer is greatly promoted. Thus, by strengthening the stirring function for the lower agitating and conveying screw 56b and maintaining the conveying capacity for the upper agitating and conveying screw 56a, the conveying ability and the agitating ability are compared with those of a single conventional agitating and conveying screw. Both can be improved.

In FIG. 3, the width of the communication port (slit) 58 communicating in the longitudinal direction between the two agitating and conveying screws 56a and 56b is made narrower along the R of the screw as shown in FIG. Also good.
This is because the holding power of the agent of the upper agitating and conveying screw 56a is increased, so that the agent can be reliably moved from the bottom to the top and from the top to the bottom. Moreover, since the wall is provided along the stirring and conveying screw, the agent can be smoothly transferred from the bottom to the top. Further, by eliminating the space away from the stirring and conveying screw, the agent can be prevented from staying between the stirring and conveying screws, and the uniformity of stirring can be improved.
In FIG. 3, the upper agitating and conveying screw 56a has a larger diameter than the lower agitating and conveying screw 56b, but may have the same diameter or vice versa.

[Example 2]
The developing device of the second embodiment will be described with reference to FIG.
The basic configuration of the developing device 5 is the same as that shown in FIGS. 3 and 4, but in this embodiment, plate-like fins 57 are provided on the shafts of the agitating and conveying screws 56a and 56b. As a result, the conveying ability in the direction perpendicular to the rotation axis is greatly improved, so that the stirring function can be further improved and more uniform mixing can be achieved.
The fin 57 can be provided in any of the two upper and lower agitating and conveying screws 56a and 56b. However, a particularly effective form is the upper agitating and conveying screw 56a in the vicinity of the downstream of the toner supply port 59. The fins 57 are provided on the lower agitating and conveying screw 56b on the downstream side.
The reason for this is described above, but since the replenished toner tends to float on the surface of the developer, it is desirable to stir the vicinity of the surface immediately after the replenishment and to quickly disperse the toner in the developer. It is most effective to mix while moving up and down between the two agitating and conveying screws 56a and 56b.
In the present embodiment, the fins 57 are attached horizontally to the axes of the stirring and conveying screws 56a and 56b, but may be inclined with respect to the axes. However, it is more effective to set it near horizontal.
Further, the number of fins 57 is not particularly limited.

The effect confirmation results of Examples 1 and 2 are shown in FIG.
FIG. 9 shows the change in the toner density at the most downstream part of the agitating and conveying screw. The horizontal axis represents the conveyance speed, and the vertical axis represents the change amount of the toner density.
In the experiment, after a certain amount of toner is charged into the toner replenishing port 59 located in the vicinity of the uppermost stream of the agitating and conveying screws 56a and 56b, the initial value and the initial value at which the toner density shows a peak at the measurement point in the most downstream portion are measured. The difference from the value was measured. Therefore, the time from the input to the detection of the peak indicates the conveyance speed, and the larger the toner density difference at the peak, the less the stirring. Note that the measurement is performed in a very small area where the toner with insufficient stirring tends to flow. Therefore, if the stirring is insufficient, the toner flows in a bundled state, and the toner concentration in the measurement area is temporarily high. Detected.

From this result, it can be seen that in Example 1, the result that the conveyance speed and the stirring ability can be greatly improved as compared with the conventional apparatus is obtained.
The two levels were compared by comparing the ratio of the lower screw pitch to the upper screw (SPR) at two levels (SPR = 1.5, 2.0).
By increasing the screw pitch of the lower screw, the conveying speed is lowered, but it is higher than the present state, while the toner density difference is lowered, and it can be seen that the stirring ability is improved.
Furthermore, in Example 2, although a conveyance speed fell a little, the result that stirring ability improved greatly was able to be confirmed.

[Example 3]
A developing apparatus according to the third embodiment will be described with reference to FIG.
The basic configuration of the developing device 5 is the same as that in FIGS. 3 and 4 and is as described in the first embodiment. In this embodiment, as shown in FIG. 6A, the stirring and conveying screws 56a and 56b An uneven shape 57a is provided on the outer peripheral surface.
The uneven shape 57a is provided for the purpose of positively moving the developer between the outer periphery of the screw and the developing container 53. For example, as shown in FIG. 6C, the rotation of the stirring and conveying screw 56b. During operation, the developer that contacts the uneven surface generates minute vortices, so that stress propagates to the developer attached to the container wall surface and can be moved.

Further, as another form of the present embodiment, FIG. 6B is an example in which a groove 57b is provided on the outer peripheral surfaces of the stirring and conveying screws 56a and 56b.
The purpose is the same as the concave / convex shape, but by making the groove shape, a regular and large vortex can be generated rather than fine irregularities, so the developer near the wall surface can be moved more actively. .

[Example 4]
A developing apparatus according to the fourth embodiment will be described with reference to FIGS.
FIG. 7 is a schematic configuration diagram of a developing device to which the present invention is applied. The basic configuration of the developing device 5 is the same as that shown in FIG. 4. The developing roller 51 is a developer carrying member, the doctor blade 52 is a developer regulating member, and the developer roller 51 is supplied with developer. A supply screw 55, and a stirring and conveying unit (powder conveying device) for receiving the developer from the supply screw 55 and conveying it with stirring by two conveying members (agitating and conveying screws) 56a and 56b and then returning it to the supplying screw 55; And a developing container 53 for accommodating them. Although not shown, the developer container 53 contains a developer composed of, for example, toner and a carrier.

A partition wall 54 is provided between the supply screw 55 and the agitating and conveying screws 56a and 56b. The supply screw 55 supplies the developer to the developing roller 51 while conveying the developer toward the front in the figure, and finishes the developing operation. It is responsible for collecting the developer.
The aforementioned partition wall 54 is eliminated at the front end in FIG. 7, and the developer is transferred from the supply screw 55 to the stirring and conveying screws 56a and 56b.
In the agitating and conveying screws 56a and 56b, the developer is agitated while the developer sent from the supply screw 55 is conveyed in the depth direction in FIG. Since the aforementioned partition wall 54 is eliminated at the rear end portions of the agitating / conveying screws 56a and 56b, the developer is transferred from the agitating / conveying screws 56a and 56b to the supply screw 55, whereby the developer is passed through the developer container. Will circulate.
Both the two agitating and conveying screws 56a and 56b have the ability to convey in the same direction on the back side in FIG. 7, and the communicating portion 60 between the two agitating and conveying screws 56a and 56b is agitated. A member 61 is provided, and there is no partition wall in the longitudinal direction between the two agitating and conveying screws 56a and 56b and the agitating member 61, and the developer can freely move up and down during the conveying. . As shown in FIG. 7, the wall surface of the communication portion 60 may have an arc shape in accordance with the movement of the tip portion of the protrusion 61a, or may have a planar shape in which the opposing wall surfaces are parallel in the vertical direction.

FIG. 8 is an explanatory diagram of the configuration of the stirring and conveying unit 56 in the longitudinal direction, and shows a part of the stirring and conveying screws 56 a and 56 b and the stirring member 61.
In the present embodiment, the protrusion 61a of the stirring member 61 is installed over the entire length of the shaft. This is installed to stir the developer being transported and the replenished toner (replenished toner) during transport.
The agitating member 61 is rotated about the longitudinal axis in conjunction with the upper and lower agitating and conveying screws 56a and 56b by a driving unit (not shown). This rotation promotes stirring of the developer that moves up and down.
As in this embodiment, the stirring member 61 provided with the protrusion 61a over the entire length is installed between the stirring and transporting screws 56a and 56b installed at the top and bottom, and is rotated around the longitudinal axis so that it can be freely transported. Agitation of the developer moving up and down is promoted, and the replenishment toner can be uniformly dispersed in the developer.
In addition, although the range which provides the protrusion 61a in the stirring member 61 is made into the full length in a present Example, the pitch of the protrusion 61a may be changed or the part provided may be limited. Further, the shape of the protrusion 61a is a quadrangular shape in the present embodiment, but the shape is not particularly limited.

As described above, the developing device of this embodiment includes the stirring member 61 that stirs the developer between the stirring and transporting screws 56a and 56b arranged in the vertical direction of the developer stirring and transporting unit. Agitation of the agent can be promoted.
Further, since the stirring member 61 is provided with a plurality of protrusions 61a around the shaft, stirring of the developer can be further promoted and mixing can be performed more uniformly.

As described above, the embodiment of the image forming apparatus according to the present invention and the specific example of the developing device having the powder conveyance device have been described. The photosensitive drum constituting the image forming unit 6 of the image forming apparatus described above. 1, the charging unit 4, the developing device 5, and the cleaning unit 2 are each configured to be detachable from the image forming apparatus main body 100. And when each reaches the end of its life, it is replaced with a new one.
The photosensitive drum 1, the charging unit 4, the developing device 5, and the cleaning unit 2 constituting the image forming unit 6 may each be a single unit, but these are integrated and detachably installed in the apparatus main body 100. It can also be a process cartridge. By using the process cartridge, the workability at the time of maintenance of the image forming unit 6 can be further improved.

1 is a schematic overall configuration diagram of an image forming apparatus showing an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration example of an image forming unit of the image forming apparatus illustrated in FIG. 1. 1 is a schematic configuration diagram of a developing device showing an embodiment of the present invention. FIG. 4 is a diagram illustrating a first embodiment of the present invention, and is a schematic explanatory diagram in a transport unit longitudinal direction of the developing device illustrated in FIG. 3. FIG. 4 is a diagram illustrating a second embodiment of the present invention, and is a schematic explanatory diagram in a longitudinal direction of a transport unit of the developing device illustrated in FIG. 3. It is a figure which shows the 3rd Example of this invention, and is a schematic explanatory drawing of a conveyance screw. It is a schematic block diagram of the developing device which shows the 4th Example of this invention. It is a schematic explanatory drawing of the conveyance part longitudinal direction of the developing device shown in FIG. It is a figure which shows the result which confirmed the effect of Example 1,2. It is a schematic block diagram which shows an example of the conventional developing device.

Explanation of symbols

1 (1Y, 1M, 1C, 1Bk): photosensitive drum (image carrier)
2: Cleaning unit 4: Charging unit 4a: Charging roller 5 (5Y, 5M, 5C, 5Bk): Developing device 6 (6Y, 6M, 6C, 6Bk): Image forming unit 8: Intermediate transfer belt 9 (9Y, 9M, 9C, 9Bk): primary transfer bias roller 10: intermediate transfer unit 19: secondary transfer roller 20: fixing unit 26: paper feed unit 27: paper feed roller 28: registration roller pair 29: paper discharge roller pair 30: paper discharge Section 31: Toner replenishment section 32: Document reading section 51: Developing roller (developer carrier)
52: Doctor blade 53: Developer container 54: Partition wall 55: Supply screw 56: Agitating and conveying unit 56a, 56b: Agitating and conveying screw (conveying member)
57: Fin 57a: Concave and convex shape 57b: Groove shape 58: Communication port (slit)
59: Toner supply port 60: Stirring member 61a: Projection

Claims (30)

It has a plurality of conveyance members having a conveyance capability in the longitudinal direction, and the plurality of conveyance members are arranged substantially in parallel in the vertical direction,
A container that accommodates the plurality of transport members and forms a single transport path;
The conveying directions of the plurality of conveying members are all the same direction with respect to the longitudinal direction,
The powder conveying method, wherein the members of the plurality of conveying members communicate with each other in a region that is at least half of the conveying member length in the longitudinal direction. In the powder conveyance method according to claim 1,
The powder conveyance method characterized by the conveyance speed of the longitudinal direction of adjacent conveyance members differing among these conveyance members. In the powder conveying method according to claim 1 or 2,
Of the plurality of conveying members, the conveying ability of the conveying member positioned below is set so that the vertical direction component is higher than the longitudinal direction component. In the powder conveyance method according to claim 3,
The conveying member has spiral blades, and the pitch of the blades of the conveying member positioned below is set to be longer than the pitch of the blades of the upper conveying member. Method. In the powder conveyance method according to any one of claims 1 to 4,
One or more fins extended substantially horizontally with a longitudinal direction are provided in the surface of the said conveyance member, The powder conveyance method characterized by the above-mentioned. In the powder conveyance method according to claim 1,
The powder conveying method, wherein the conveying member is a screw member having a spiral blade, and an uneven shape is provided on an outer peripheral surface of the spiral blade. In the powder conveyance method according to claim 6,
The powder conveying method, wherein the conveying member is a screw member having a spiral blade, and a plurality of groove shapes are provided on an outer peripheral surface of the spiral blade. In the powder conveyance method according to claim 1,
A powder conveying method, wherein a stirring member is provided between conveying members arranged substantially in parallel in the vertical direction. In the powder conveyance method according to claim 8,
The powder conveying method, wherein the stirring member is provided with a plurality of protrusions around a shaft. It has a plurality of conveyance members having a conveyance capability in the longitudinal direction, and the plurality of conveyance members are arranged substantially in parallel in the vertical direction,
A container that accommodates the plurality of transport members and forms a single transport path;
The conveying directions of the plurality of conveying members are all the same direction with respect to the longitudinal direction,
The powder conveying apparatus characterized in that the members of the plurality of conveying members communicate with each other in a region that is at least half of the conveying member length in the longitudinal direction. In the powder conveying apparatus according to claim 10,
A powder conveying apparatus, wherein among the plurality of conveying members, adjacent conveying members have different conveying speeds in the longitudinal direction. In the powder conveying apparatus according to claim 10 or 11,
Of the plurality of conveying members, the conveying capacity of the conveying member positioned below is set such that the vertical direction component is higher than the longitudinal direction component. In the powder conveying apparatus according to claim 12,
The conveying member has spiral blades, and the pitch of the blades of the conveying member positioned below is set to be longer than the pitch of the blades of the upper conveying member. apparatus. In the powder conveying apparatus according to any one of claims 10 to 13,
One or more fins provided in the surface of the said conveyance member are extended substantially horizontally with a longitudinal direction, The powder conveyance apparatus characterized by the above-mentioned. In the powder conveying apparatus according to claim 10,
The powder conveying device, wherein the conveying member is a screw member having a spiral blade, and an uneven shape is provided on an outer peripheral surface of the spiral blade. In the powder conveying apparatus according to claim 15,
The powder conveying apparatus, wherein the conveying member is a screw member having a spiral blade, and a plurality of groove shapes are provided on an outer peripheral surface of the spiral blade. In the powder conveying apparatus according to claim 10,
A powder conveying device, wherein a stirring member is provided between conveying members arranged substantially in parallel in the vertical direction. In the powder conveying apparatus according to claim 17,
The powder conveying apparatus, wherein the stirring member is provided with a plurality of protrusions around a shaft. A developer made of powder;
A developer carrier for carrying the developer;
A supply unit for supplying developer to the developer carrier;
An agitation transport unit for receiving the developer from the supply unit, transporting the developer while stirring, and then returning the developer to the supply unit;
A developing device comprising:
The stirring and conveying unit is
It has a plurality of conveyance members having a conveyance capability in the longitudinal direction, and the plurality of conveyance members are arranged substantially in parallel in the vertical direction,
A container that accommodates the plurality of transport members and forms a single transport path;
The conveying directions of the plurality of conveying members are all the same direction with respect to the longitudinal direction,
The developing device characterized in that the members of the plurality of conveying members communicate with each other in a region that is at least half of the conveying member length in the longitudinal direction. The developing device according to claim 19, wherein
A developing device, wherein among the plurality of transport members, adjacent transport members have different transport speeds in the longitudinal direction. The developing device according to claim 19 or 20,
Among the plurality of transport members, the transport capability of the transport member positioned below is set such that the vertical direction component is higher than the longitudinal direction component. The developing device according to claim 21, wherein
2. The developing device according to claim 1, wherein the conveying member has spiral blades, and the pitch of the blades of the conveying member positioned below is set to be longer than the pitch of the blades of the upper conveying member. The developing device according to any one of claims 19 to 22,
2. A developing device according to claim 1, wherein at least one fin extending substantially horizontally with the longitudinal direction is provided on the surface of the conveying member. The developing device according to claim 19, wherein
The developing device according to claim 1, wherein the conveying member is a screw member having a spiral blade, and an uneven shape is provided on an outer peripheral surface of the spiral blade. The developing device according to claim 24,
The developing device according to claim 1, wherein the conveying member is a screw member having a spiral blade, and a plurality of groove shapes are provided on an outer peripheral surface of the spiral blade. The developing device according to claim 19, wherein
A developing device, wherein a stirring member is provided between conveying members arranged substantially in parallel in the vertical direction. The developing device according to claim 26, wherein
The developing device, wherein the stirring member is provided with a plurality of protrusions around a shaft.   A process cartridge in which an image carrier and the developing device according to any one of claims 19 to 27 are integrated.   An image forming apparatus comprising: an image carrier; and the developing device according to claim 19.   An image forming apparatus comprising the process cartridge according to claim 28.

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