JPS58202467A - Developing device of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent deflection of a magnetic toner, and also to detect a residual quantity of the magnetic toner by detecting the rotation, by providing a roll in the vicinity of a developing sleeve, and rotating it by a flow of the magnetic toner. CONSTITUTION:A roll 8 is provided so as to be freely rotatable in parallel through a developing sleeve 3 and a gap G. A replenishing toner 11 is supplied to the right side of the roll 8, is attracted to the circumferential face of the developing sleeve 3, passes through the gap G and moves in the direction of a doctor blade 6. The roll 8 is rotated by receiving the rotating force in the direction as indicated with an arrow by the magnetic toner 11 passing through the gap G. The magnetic toner 11 going toward the doctor blade 6 is limited by the gap G, therefore, the magnetic toner 11 does not collect one-sidedly in the vicinity of the doctor blade 6, flocculation of a toner is prevented, and since rotation of the roll 8 shows a residual quantity of a magnetic toner, the residual quantity can be detected exactly by an output of a detecting element for detecting a rotation of the roll 8.

Description

[Detailed description of the invention] The invention relates to the dry developing device used.

■In component development, magnetic toner is used and is magnetically attracted to a rotating sleeve to form a magnetic brush that sweeps the photoreceptor, but the history on the sleeve after development is a problem. become. That is, the influence of the previous image appears on the next image, degrading the image quality.

FIG. 1 shows a conventional developing device that solves the above problem. 1 is a belt-shaped photoreceptor, and a pulley 2
Drive in the direction of the arrow. Reference numeral 3 denotes a developing sleeve which rotates in the direction of the arrow and attracts the magnetic toner l1 onto its surface by a magnet 4 fixedly arranged inside. A developing tank 5 containing magnetic toner 11 extends below the developing sleeve 8 with a narrow gap.

This developing device stores magnetic toner 11 and developer 1 in a developing tank 5.
By sufficiently expanding the area of contact with the developing sleeve 3, the above-mentioned hysteresis phenomenon can be almost eliminated.However, on the other hand, the force of conveying the magnetic toner 11 by the developing sleeve 3 is extremely large, so the problem shown in FIG. As shown, the magnetic toner 11 is biased toward the doctor blade 6 side, and toner aggregation becomes a problem. Further, if the sensor 7 for detecting the amount of toner is installed at the position shown in the figure, it will issue a signal indicating that there is a shortage even though 1 of the magnetic toner l1 is sufficient.

The present invention aims to solve the above-mentioned problems, and by providing a roller close to the developing sleeve and rotating it with the flow of magnetic toner, the present invention prevents the magnetic toner from being biased. By detecting the rotation, the remaining amount of magnetic toner is detected.

Next, the present invention will be explained based on the embodiments shown in FIGS. 2 and 3.

A roller 8 is rotatably supported by a bearing 12 attached to a side wall 5α of the developing tank 5, and faces the developing sleeve 3 in parallel with a gap G therebetween. This gap G is approximately 0.3 to 2 m, but its appropriate value depends on the strength of the magnet and the properties of the magnetic toner 11.

The roller 8 is made of a non-magnetic material and faces the magnetic pole of the magnet 4. As shown in FIG. 3, a shutter 18 is fixed to the end of the roller 8 with a screw 15, which blocks the optical path of the photointerrupter 14. In addition,
IO is the agitator and 9 is its axis.

The replenishment toner is supplied upstream of the roller 8 (on the right side in the figure). The magnetic toner 11 attracted to the surface of the developing sleeve 3 moves in the direction of the doctor blade 6 as it rotates, but on the way, it has to pass through the gap G between it and the roller 8, so there is a limit there. receive.

By the magnetic toner 11 passing through the roller 8,
The receiver rotates due to the rotational force in the direction of the arrow. This rotation causes the shutter 13 to rotate and intermittently interrupt the optical path of the photointerrupter 14.

If the gap G is too small, the amount of magnetic toner 11 that can pass through it will be small, and the magnetic toner 11 will accumulate in front of the roller 8, causing the magnetic toner 11 to flow from the lower end of the developing tank 5.
will be overflowing. On the other hand, if the gap G is too wide, the regulating effect of the roller 8 will be lost, resulting in the state shown in FIG.

Therefore, the gap G is adjusted to be as narrow as possible without overflowing the magnetic toner 11 from the lower end of the developing tank 5. In this way, the magnetic donor 11 is restricted by the roller 8, but because the roller 8 is free to rotate, it is not subjected to much load therefrom. Especially roller 8
The load is further reduced by making it face the magnetic pole of the magnet 4.

The rotation of the roller 8 by the magnetic toner 11 gradually slows down as the magnetic toner 11 in the developer tank 5 decreases, and eventually stops. Since this state can be detected by the output of the photointerrupter 14, the remaining amount of the magnetic toner 11 can be detected based on the output signal.

As described above, the present invention disposes the roller close to and opposite the developing sleeve, thereby restricting the magnetic toner toward the doctor blade. Therefore, it is possible to prevent the magnetic toner from being biased near the doctor blade, and the resulting magnetic It is possible to eliminate toner aggregation. Since the roller can rotate freely, there is little load on the magnetic field 1, which is subject to certain limitations, and there is no risk of agglomeration there. Furthermore, is the rotation of the roller caused by magnetic toner the amount of remaining magnetic toner? Therefore, the remaining amount can be accurately detected by the output of the detection element that detects the rotation of the roller.

[Brief explanation of drawings]

FIG. 1 is a front view of a conventional developing device, FIG. 2 is a front view of an embodiment of the present invention, and FIG. 8 is a side view showing rotation detecting means. 8... Actual one-dimensional three, 4... Magnet, 8...
...Roller, 11...Magnetic toner, ■3...Shutter, ■4...Photo interrupter. Patent applicant Rico Co., Ltd. −

Claims (1)

[Claims] A developing sleeve that rotates while magnetically attracting magnetic toner on its peripheral surface to form a magnetic brush, a roller that is disposed close to and opposite to the developing sleeve, and a detection element that detects rotation of the roller. Electrophotography is characterized in that it receives a rotational force from the magnetic toner conveyed by the developing sleeve, regulates the amount of conveyance of the magnetic toner, and the output of the detection element is used to display the residual acid of the magnetic toner. Copying machine developing device.