JP2005070285A - Toner-replenishing device for electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily mix and stir toner and developer according to the increase of the replenished toner quantity per unit time, when supplying the toner corresponding to high-density printing, and to prolong the lifetime of the developer, in a toner-replenishing device equipped with a mechanism of carrying the toner by a helical rotating body. <P>SOLUTION: Regarding the toner replenishing device for an electrophotographic image forming apparatus equipped with the mechanism of replenishing the toner to the developing device by the helical rotating body, the toner supply port of the toner-replenishing device for carrying the toner from the helical rotating body to the developing device is formed into a shape so as to have the function of making the replenished toner quantity dispersed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a toner replenishing device.

  In an image forming apparatus that records and forms a toner image using a known electrophotographic process such as a laser printer or a copying machine, the developing device is a developing machine that develops toner on a photosensitive member, and the toner is consumed adjacent to the developing machine. The toner supply device is configured to supply toner to the developing device. As a method of replenishing toner to the developing machine, a method of providing a spiral rotating body in the toner replenishing device and rotating the toner to transport the toner in the axial direction to replenish the developing machine is general. It is.

  The prior art will be described with reference to FIGS. In FIG. 2, the toner replenishing device 1 contains toner 2 in a container that contains toner, and a toner feed screw 3 that is a spiral rotating body for conveying the toner 2 is provided in the lower part of the container. An agitator 4 as a rotating body is provided above the toner feed screw 3 to stir the toner 2 in the container to prevent the toner from adhering to the wall of the container and to aggregate the toner over time due to the weight of the toner itself. When the toner feed screw 3 rotates and the toner is replenished to the developing device 9 shown in FIG. 6, the toner is always supplied to the toner feed screw 3 and the toner is stably supplied by preventing and stirring. Replenishment is possible. Further, as shown in FIG. 5, there is a supply port 7 for supplying toner to the developing machine in the front end direction of the toner feed screw 3, that is, the toner transport direction 6. It is common that. In this case, when the toner feed screw 3 is rotated and the toner is conveyed toward the toner supply port 7, the toner supply screw 7 has almost the same width as the toner feed screw 3. Since it falls all at the same time when it moves to 7, it is replenished in a local part.

  In FIG. 6, the mixing and stirring of the toner and the developer 12 in the developing device 9 will be described. The developer 12 of the developing machine 9 is always conveyed in the axial direction by an auger screw 13 that is a spiral rotating body, and a toner control sensor that detects the toner concentration in the developer while the developer 12 is being conveyed. There are 14. When the toner concentration in the developer decreases by printing, the toner control sensor 14 detects the toner concentration, and the toner is supplied from the toner supply device 1 to the developing device 9. The replenished toner 11 is mixed and stirred with the developer 12 by the auger screw 13. Since it takes time for the developer 12 to move from the toner replenishment portion to the toner control sensor 14, the printing apparatus may perform high-density printing that requires further toner replenishment during this time. There is a case where printing with almost no printing is performed so that it is not necessary to supply toner. When the toner control sensor 14 determines that the toner density is low and replenishes the toner in order to prevent the toner from being overfilled, the toner is replenished only for a certain amount, that is, for a certain period of time. When the toner 13 is conveyed while being agitated and mixed with the developer 12 by the screw 13 and arrives on the toner control sensor 14, the toner density is judged again. If the toner density is still low, the toner is replenished for a predetermined time again. . Therefore, the toner supply is intermittent, and when the toner is supplied with a screw, the supply position becomes one point, so that a large amount of toner is supplied to one place and it becomes difficult to mix with the developer. is there.

  In recent years, the printing density of printing paper has increased, and a developing machine and a toner replenishing device corresponding to the printing density have become necessary. As the toner replenishing device, the amount of toner developed from the developing device to the photosensitive member increases as the printing density increases, so it is necessary to replenish the shortage of toner, and supply toner to the developing device per unit time. It is necessary to increase the amount. For this purpose, methods such as increasing the number of rotations of the toner feed screw or increasing the outer diameter of the screw portion have been taken. However, increasing the amount of toner replenished per unit time means that a large amount of toner is put into the developing machine at one time, and the state where the toner is not sufficiently agitated and the developer does not charge up is printed. The fog and shading appear on the printed paper. As a countermeasure, it is possible to reduce the supply amount of toner per unit time. However, in this case, there is a problem that it is not possible to follow the printing of sufficiently high density printing. In addition, in order to increase the charge of the developer, a method of extending the length of the auger screw for mixing and stirring the toner in the developing machine and extending the stirring time can be raised, but in this case, the toner concentration of the developer in the developing machine has decreased. When the toner control sensor senses this and replenishes the toner, it takes a long time for the sensor to recognize that the toner concentration in the developer has recovered due to the length of the auger screw in the stirring portion. It becomes dull. Since the reaction becomes dull, it is expected that the toner will be replenished excessively, which causes density unevenness. As a solution to this, if the rotation time of the auger screw is increased to shorten the time to reach the toner control sensor after the toner is replenished, the reaction becomes quicker and excessive supply of toner can be prevented. However, on the other hand, there is a problem that stress is generated in the developer due to high rotation of the auger screw and the life of the developer is shortened.

  As described above, in the prior art, it is not possible to follow high printing density printing in order to reduce the amount of toner replenishment, or to follow high printing density because the rotation speed of the mixing auger screw in the developing machine is increased. However, there is a problem that the life of the developer is shortened.

  The object of the present invention is to enable high-density printing and to replenish toner without reducing the amount of toner replenished per unit time, and excessively stress the developer during mixing and stirring of toner and developer in the developing machine. The object is to extend the life of the developer without giving it.

  The above object is achieved by providing the toner supply port to the developing device of the toner supply device with a function of dispersing the toner supply amount.

  According to the present invention, by changing the shape of the toner replenishing port of the toner replenishing device, the toner can be replenished while being dispersed in a large amount at a time, so that fog and density differences can be reduced in correspondence with high printing density printing. I can do it.

  Embodiments of the present invention will be described below with reference to FIGS. 1, 2, 3, and 4. FIG.

  1 and 2, the toner replenishing device 1 contains toner 2 in a container, and a toner feed screw 3 that is a spiral rotating body for conveying the toner 2 is provided at the lower part of the container. An agitator 4 that is a rotating body is provided above the toner feed screw 3, and the toner 2 is agitated to prevent the toner from sticking into the container and to stably supply the toner to the toner feed screw portion. In the front end direction of the toner feed screw 3, that is, the toner transport direction 6, there is a toner supply port 7 for supplying toner to the developing machine, and the shape thereof is along the transport direction 6 by the toner feed screw 3 as shown in FIG. 1. The opening 16 is gradually widened. If the opening is simply made long, most of the toner falls at the tip of the opening, and a large amount of toner enters at once. Therefore, by reducing the opening at the tip, the amount of toner falling from the opening at the tip can be reduced, and the width of the opening gradually increases as the toner is conveyed. The toner remaining on the screw part is continuously dropped, and it is possible to drop the toner little by little from the front end to the rear end part of the opening portion instead of a large amount of toner at one time. The amount of supply per hit is not changed. The reason why the rear end portion is widened is to replenish all the toner conveyed by the toner feed screw 3 to the developing machine. If it remains in the toner feed screw portion, it accumulates and agglomerates the toner. This is because the end bearings are damaged.

  By replenishing the toner little by little, it is possible to suppress a local increase in the toner concentration in the developer, so that the toner and the developer are easily stirred and mixed, and the developer is likely to be charged. Therefore, since it is not necessary to increase the length of the auger screw for mixing and stirring in the developing machine, it is not necessary to increase the rotation speed of the auger screw, and the life of the developer is not shortened.

  FIG. 3 shows another example of the toner supply port 7. In this example, the portion of the replenishing port 7 that restricts the amount of toner falling is rectangular, and the width thereof is shorter than the outer diameter of the toner feed screw (one shorter than the difference between the outer diameter of the screw and the shaft diameter). The length is longer than the outer diameter of the screw. Since the width is narrowed, the toner is difficult to fall off and the toner is dispersed and replenished, and the same effect is obtained.

  FIG. 4 shows still another example of the toner supply port 7. In this example, a plurality of toner replenishing ports 7 are provided, and the same effect is obtained by setting the opening area so that the toner does not fall at each replenishing port except for the last part of the replenishing port.

1 is a cross-sectional view of a toner replenishing device according to the present invention. (Example 1) FIG. 3 is a schematic diagram of a toner replenishing device. 1 is a cross-sectional view of a toner replenishing device according to the present invention. (Example 2) 1 is a cross-sectional view of a toner replenishing device according to the present invention. Example 3 Sectional drawing of a conventional toner replenishing device. 1 is a schematic configuration diagram of an electrophotographic image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Toner replenishment apparatus 2 Toner 3 Toner feed screw 4 Agitator 6 Toner conveyance direction 7 Toner supply port 9 Developing machine 10 Photoconductor 11 Replenishment toner 12 Developer 13 Auger screw 14 Toner control sensor

Claims (3)

  In a toner replenishing device in an electrophotographic image forming apparatus having a mechanism for replenishing toner to a developing device with a spiral rotating body, the toner of the toner replenishing device in which the toner is conveyed from the spiral rotating body to the developing device A toner replenishing device in an electrophotographic image forming apparatus, wherein a shape of a supply port has a function of dispersing a toner replenishing amount.   2. The toner replenishment in an electrophotographic image forming apparatus according to claim 1, wherein the toner supply port is narrowed and gradually widened with respect to a toner conveying direction by the spiral rotating body. apparatus. The toner replenishing device in an electrophotographic image forming apparatus according to claim 1, wherein a plurality of the toner supply ports are provided in a toner transport direction by the spiral rotating body.

Images