JPS6262354B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for collecting toner adhering to a photoreceptor after transfer in an electronic copying machine using a magnetic brush developing device.

Conventionally, there have been toner collection devices that drop the toner collected by a cleaning device in front of the developing device and disperse the toner using a conveyance mechanism within the developing device, and toner that replenishes the toner collected by the cleaning device to the developing device. There is a toner recovery device that drops toner in a concentrated manner in the center of a toner supply tank and disperses the toner using a toner supply mechanism within the toner supply tank.

In the former case, the mechanism inside the developing device becomes complicated and the volume for accommodating the developer becomes smaller.
There are disadvantages in that the number of drive shafts increases and that toner agitation in the longitudinal direction of the developing device is generally insufficient.

In the latter case, the amount of toner in the center of the toner replenishment tank increases and the agitation cannot keep up, resulting in uneven image density, and a large load is placed on a longitudinal part of the toner replenishment mechanism, reducing the durability of the toner replenishment mechanism. There are drawbacks that reduce it.

An object of the present invention is to transfer the toner collected by a cleaning device having different properties such as composition ratio and charge amount to the toner in the developing device into the developing device or a toner supply tank approximately in the longitudinal direction of the toner. To provide a toner collection device capable of dropping toner in uniform amounts.

The present invention will be explained in detail based on the embodiments illustrated below.

In FIG. 1, reference numeral 1 indicates a drum-shaped photoreceptor, and this photoreceptor 1 is rotated in the direction of the arrow by a driving means (not shown). A developing device 2, a transfer device 3, a cleaning device 4, a charging device, an exposure device, etc. (not shown) are arranged near the photoconductor 1 at predetermined positions, and form an electrostatic latent image on the photoconductor 1. The process of developing this electrostatic latent image with toner, transferring the toner image onto transfer paper, and cleaning the toner adhering to the photoreceptor 1 after the transfer can be repeated.

The developing device 2 supplies toner of a developer 2b made of iron powder or magnetic powder and toner contained in a developer tank 2a to the surface of the photoreceptor 1 to develop an electrostatic latent image. . A pumping roller 2c is arranged so that its lower part is buried in the developer 2b in the developer tank 2a, and the pumping roller 2c surrounds a plurality of permanent magnets 2d fixed to an immovable shaft. Sleeve 2 rotated in the direction of the arrow
It consists of e. The developer 2b in the lower part of the developer tank 2a is attracted to the circumferential surface of the sleeve 2e and drawn up by the magnetic force of the permanent magnet 2d. Pumping roller 2
A first developing roller 2f and a second developing roller 2g are arranged above c. First developing roller 2f
shows a permanent magnet 2h fixed to an immovable shaft and a sleeve 2 surrounding them and rotating in the direction of the arrow.
Similarly, the second developing roller 2g includes a permanent magnet 2j fixed to an immovable shaft and a sleeve 2k surrounding the permanent magnet 2j and rotating in the direction of the arrow. The developer on the upper part of the pumping roller 2c is moved upward on the circumferential surface of the sleeve 2i by the magnetic force of the permanent magnet 2h, and then moved upward on the circumferential surface of the sleeve 2k by the magnetic force of the permanent magnet 2j. In order to shape the magnetic brush on the circumferential surface of the sleeve 2i of the first developing roller 2f, a doctor 2l is provided with a screw or the like at an end of the developer tank 2a near the first developing roller 2f. Sleeve 2i, 2k
Magnetic brushes are formed on the circumferential surface of the photoconductor 1, and these magnetic brushes supply toner to develop the electrostatic latent image formed on the circumferential surface of the photoreceptor 1, and the developed toner image is transferred to the transfer device 3. is transferred onto a transfer paper, and the transfer paper is separated from the photoreceptor 1 by a separating device 6.

A developer scraping plate 7 is arranged near the second developing roller 2g to scrape off the developer after development. A stirring member 8 is arranged below the developer scraping plate 7. A toner concentration sensor 9 is disposed on the developer scraping plate 7 and a passage plate provided opposite to the developer scraping plate 7. The toner concentration sensor 9 detects the toner concentration and generates a toner replenishment signal when the concentration is lower than a certain value. ing. A toner replenishment tank 10 containing toner is disposed above the developing device 2, and a replenishment control roller 11 is provided at a lower opening of the toner replenishment tank 10. The replenishment control roller 11 is rotated in response to a replenishment signal from the toner concentration sensor 9, and drops a predetermined amount of toner into the developer tank 2a.

The cleaning device 4 includes a roll brush 4a that is rotated in a direction opposite to the rotation direction of the clock hands in FIG. It consists of a blade 4b and a box 4c that surrounds the blade 4b and prevents toner from scattering. The toner is scraped off from the photoreceptor 1 by the blade 4b, and then swept to the bottom of the box 4c by the roll brush 4a.

A tube 12 with an open top is provided at the bottom of the box 4c, and a helical coil 13 that is rotated in a fixed direction by a driving means (not shown) is provided on the tube 12. The swept toner is conveyed to the outlet of tube 12. The bottom of the box 4c is located above the upper end of the developing device 2, and a tube 14 through which toner passes is disposed between the outlet of the tube 12 and the developing device 2. The end 14a of the tube 14 located at the upper part of the developing device 2 is provided along the longitudinal direction of the developing device 2 (the longitudinal direction of the drum-shaped photoreceptor 1), and has an open lower end. The opening is closed by the bottom plate 14b. A helical coil 15 is provided inside the tube 14, as shown in FIGS. 1 and 2. A shaft 16 of this helical coil 15 projects outside the tube 14, and a gear 17 is fixed to this shaft 16. This gear 17 is a chain driven in the direction of the arrow by a drive means (not shown). 18 is being worked on, helical coil 15
is rotated in a fixed direction. The toner entering the tube 14 from the outlet of the tube 12 is conveyed toward the developing device 2 by the helical coil 15.

Since a means such as a helical coil 15 for conveying toner is provided in the tube 14, the cleaning device 4 may be placed at a lower position than the developing device 2. A tube 14 located above the developing device 2
As shown in FIG. 2, a wedge-shaped hole 19 is formed in the bottom plate 14b of the end 14a of the tube 14, the width of which gradually increases in the direction of toner travel.
The toner inside is dropped in a substantially uniform amount in the longitudinal direction of the developing device 2. Bottom plate 14 for dropping toner
The holes 19 b are not limited to those described above, but may include, for example, a plurality of circular holes 19 having diameters that gradually increase in the toner traveling direction, as shown in FIG.
It may be.

Another example of the invention is shown in FIG. In the example shown in FIG. 4, a toner replenishing tank 2 is provided on the farthest side from the photoreceptor 1 of the developer tank 2a.
The configuration other than the configuration in which the toner collected by the cleaning device 4 is dropped into the cleaning device 4 and the configuration in which the toner in the toner supply tank 20 is supplied to the developing device 2 is the first configuration.
This is the same as the example shown in the figure. The example toner replenishing device shown in FIG. 4 will be explained. Above toner supply tank 2
An opening is provided at the top of the toner supply tank 20 and the developer tank 2a are communicated with each other. Inside the toner replenishment tank 20, a toner replenishment plate 22 for throwing toner into the developer tank 2a is disposed on a rotating shaft 21 rotated by a drive means (not shown). The toner supply plate 22 is
It operates in response to a replenishment signal from the toner concentration sensor 9, and rotates at a constant speed when the toner is soaked in the toner, and then suddenly rotates quickly when the toner is near the mouth to remove the toner from the mouth. From the developer tank 2a
Throw it inside. A substantially uniform amount of toner is dropped from the end 14a of the tube 14 in the longitudinal direction of the toner supply tank 20 (the longitudinal direction of the drum-shaped photoreceptor 1), as in the example shown in FIG.

According to the present invention, the toner collected by the cleaning device can be dropped into the developing device or the toner supply tank in a substantially uniform amount in the longitudinal direction of the developing device or the toner supply tank by a simple means.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the toner recovery device of the present invention, FIG. 2 is a partially cutaway slope view showing the main parts of the same device, and FIG. 3 is a slope view showing the main parts of the same device. 1 and 4 are partially cutaway front views showing other embodiments of the above device. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... Developing device, 3... Transfer device, 4... Cleaning device, 2c... Drawing roller, 2f... First developing roller, 2g... Second developing roller, 10... Toner Supply tank, 12...
Tube, 13... Helical coil, 14... Tube, 15
...Helical coil, 19...hole, 20...toner supply tank.

Claims (1)

[Claims] 1. In an electronic copying machine that repeatedly performs charging, exposure, development, transfer, and cleaning, and in which development is performed by a magnetic brush developing device, a tube through which toner collected from the photoreceptor by the cleaning device passes is connected to the cleaning device and the developing device. Alternatively, a means for transporting toner is provided in the tube between the developing device or the toner replenishing device, and one end of the tube above the developing device or the toner replenishing device is arranged along the longitudinal direction of the developing device or the toner replenishing device. A toner recovery device characterized in that an opening is formed in the lower part of the device to allow the toner being conveyed to fall almost uniformly in the longitudinal direction of the developing device or the toner replenishing device.