JPH01237577A - Developing device for electrophotographic printer - Google Patents

Abstract

PURPOSE:To simplify the assembly by providing a positioning means of a doctor blade and a guide plate as one body with a bearing member of a magnet roller. CONSTITUTION:On a bearing member 20 of a magnet roller 11, a part 20a for positioning the tip of a doctor blade 13, and a part 20b for positioning the tip of a guide plate 12 are provided as one body. Also, as for the doctor blade 13, its tip is controlled by the bearing members 20, 20a, and it is fixed to a side wall of a developing case 8 through screws 21, 22, and with regard to the guide plate 12, as well, in the same way, its tip is controlled by the bearing members 20, 20b, and it is fixed to the side wall of the developing case 8 through a screw 23. In such a way, the assembling work is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device for an electrophotographic printing machine, and more particularly to a developing device of this type that uses a two-component developer consisting of a carrier and a toner. The present invention relates to a developing device for an electrophotographic printing machine that can obtain stable print density by narrowing the toner density management range.

[Conventional technology]

Prior to explaining the present invention, the configuration of a conventional developing device for an electrophotographic printing machine will be explained based on FIGS. 6 to 8.
6 and 7 are vertical sectional views showing the internal structure of the conventional developing device 1 (examples of different behaviors of the developer 9) during operation of an electrophotographic printing machine, and FIG. FIG. 2 is a vertical cross-sectional view showing the internal structure of only the developing device 3 taken out from the conventional developing device 1 shown in FIG.

In FIG. 6, the developing device [1 is the hopper 2 and the developing device 3].
It is composed of. The toner 4 is stored in a hopper case 5, and when the toner replenishment roller 6 is driven, the toner 4 is transferred from the replenishment lower to the developing case 8 of the developing device 3.
supplied within. The developer 9 in the developing device 3 is moved by the stirring blade 1
0 is stirred by rotating in the force direction of arrow Fz, and the two components of the developer 9, the carrier (iron powder) and the toner, are each charged by friction and charged.

The outermost non-magnetic (aluminum) sleeve 11a of the magnetic roller 11 rotates in the direction of arrow F2 to convey the developer 9. The amount of developer 9 guided to the lower surface of guide plate 12 is regulated by the tip of doctor blade 13, and by the magnetic pole arrangement of magnet roller 11,
Ears 14 of the developer 9 are formed and used for developing a photoreceptor (not shown). On the other hand, the amount of developer 9 transported is large.

The surplus is used by automatic toner concentration sensor (hereinafter referred to as ATC).
)15 sensor heads 15a and guide plate 1
The liquid flows between the bent portions 12a of No. 2, slides down the upper surface of the guide plate 12, and is returned to the stirring blade 10. The ATC 15 then detects a change in reactance caused by a change in magnetic permeability of the developer 9 in contact with the sensor head 15a.

Changes in the resonance frequency due to changes in actance are converted into voltage, and the amount of toner 4 supplied is feedback-controlled.

The prior art of a developing device for an electrophotographic printer equipped with an ATC is described in, for example, Japanese Utility Model Application No. 62-71650.

[Problem to be solved by the invention]

Therefore, in FIG. 6, in order to stably obtain high-density printing within a practical range, it is important to manage the toner concentration in the developer 9 in a small band.
Uniform pressure (density) on the entire surface of the ATC head 15a
It is necessary to bring the developer 9 into contact. Here, the problems in bringing the developer 9 into uniform contact with the entire surface of the ATC head 15a will be explained based on FIG. 8.

In FIG. 8, the gap g between the tip of the doctor blade 13 and the magnetic roller sleeve lla, and also the gap g between the guide plate 12 and the magnetic roller sleeve lla
Due to variations in the assembly dimensions of the gap G between the sensor head 15a and the ATC head 15a, the amount of developer 9 conveyed to the ATC head 15a changes, and in extreme cases, as shown in FIG. In this case, even if the toner concentration in the developer 9 is lower than the specified value, the normal contact state h=o is maintained. In comparison, due to the presence of the air layer, its magnetic permeability decreases, the output voltage of the ATC 15 decreases, the toner density is determined to be high (that is, the ATC 15 determines that the air layer is toner), and the developing material is removed from the hopper 2. The toner 4 will not be replenished into the container 3, resulting in low density image quality.

On the other hand, when g is small and G is large in FIG. Even if the output voltage of ATC15 becomes high and the toner density is high, the ATC15
determines that the toner density is low, issues a command to replenish toner, and toner is replenished from hopper 2 to developing device 3. As a result, in this case, overtoner is produced, which also causes poor image quality. Become.

In this way, in order to keep the print density of the developing device for an electrophotographic printing machine stable, it is very important to control the dimensions of the gaps g and G shown in FIG. g and G are adjusted to assemble the developing device 3, but the doctor blade 13. Both guide plates 12 have a long width, so the gap adjustment described above can be performed on both the left and right sides.

It was necessary to carry out the process at three locations, including the center, which not only had poor work efficiency but also required a lot of manpower, which contributed to the high product cost.

The purpose of the present invention is to provide a gap between a doctor blade and a magnetic roller sleeve that regulates the amount of developer supplied to a photoconductor, and a gap between a guide plate and a magnetic roller sleeve that guide developer to an ATC head and a doctor blade. The developer assembly can be easily and precisely maintained without using conventional gap spacers, which are inefficient, such as adjusting the long doctor blade and guide plate at three locations on the left, right, and center positions. It is an object of the present invention to provide an inexpensive developing device for an electrophotographic printing machine which is capable of producing a large amount of energy and is excellent in terms of labor saving.

[Means to solve the problem]

The purpose is to install a magnetic roller that supplies developer to the photoreceptor and an automatic toner 1 that automatically detects the toner density.
a doctor blade that regulates the amount of developer supplied to the photoconductor via a magnetic roller, and a guide plate that guides the developer to the sensor head of the automatic toner density sensor and the doctor blade. This is achieved by providing positioning means for the doctor blade and the guide plate integrally with the bearing member of the magnet roller in the developing device of the electrophotographic printing machine.

[Effect]

According to the present invention having the above configuration, the doctor blade and the guide plate are positioned integrally with the bearing member that pivotally supports both ends of the magnet roller, that is, the doctor blade that regulates the amount of developer supplied to the photoreceptor. blade and AT
By providing a means for positioning the guide plate that guides the developer to C and the doctor blade, it is possible to perform tasks such as adjusting the conventional gap spacer, that is, the long doctor blade and guide plate at three locations on the left, right, and center. Without using inefficient gap spacers, it is possible to easily and accurately maintain the gap between the doctor blade and the magnetic roller sleeve, as well as between the guide plate and the magnetic roller sleeve, and assemble the developing device.

〔Example〕

Hereinafter, the present invention will be explained based on an embodiment shown in FIGS. 1 to 5. FIG. 1 is a vertical sectional view showing the internal structure of the developing device 3, and FIG. 2 is a vertical sectional view showing the internal structure of the developing device 3. A longitudinal sectional view showing the side wall structure of the developing case 8 with all parts removed;
3 is a perspective view of the bearing member shown at 20 in FIG. 1, FIG. 4 is a sectional view taken along line AA' in FIG. 1, and FIG. 5 is a perspective view of the guide plate shown at 12 in FIG. It is.

In FIG. 1, the magnet roller 11 is indicated by a dashed line, and the bearing member 20 of the magnet roller 11
is the part 2 for positioning the tip of the doctor blade 13
0a, and a portion 20b for positioning the tip of the guide plate 12.
are integrated. Doctor blade 13 is
The tip of the guide plate 12 is regulated by a bearing member 20 (20a) and fixed to the side wall of the developing case 8 via screws 21.22, and the tip of the guide plate 12 is similarly regulated by a bearing member 20 (20b). and is fixed to the side wall of the developing case 8 via screws 23.

The parts shown in FIG. 3, namely the doctor blade 13 and the guide plate 12. The second image shows a state with the bearing member 20 removed.
In the figure, the side wall of the developing case 8 has screw holes 24a and 24b for fixing the doctor blade 13, and a guide plate 12.
A screw hole 25 is provided for fixing the bearing member 20, an insertion hole 26b for inserting the positioning portion 20a of the doctor blade 13, and an insertion hole 26c for inserting the positioning portion 20b of the guide plate 12. is provided.

In FIG. 3, which is a perspective view of the bearing member 2o, the bearing member 20 made of plastic material includes a ball bearing 2.
7 is incorporated, and as described above, the tip positioning part 20a of the doctor blade 13 and the tip positioning part 20b of the guide plate 12 are integrally molded, and the boss part 282 position that fits into the developing case 8 is Accurate fitting is obtained by the mating portion 29.

FIG. 4, which is a sectional view taken along line AA' in FIG. 1, shows the developing case 8.
The positioning portion 20a of the doctor blade 13 (
) and the positioning portion 20 of the guide plate 12. b pass through the insertion openings 26b and 26c (see FIG. 2) of the developing case 8, respectively, and protrude inward from the inner wall of the developing case 8 by a certain amount. Furthermore, a protrusion 32 of the guide plate 12 shown in FIG. 5 fits into the slit 30 of the positioning portion 20b of the bearing member 20.

In addition, in FIG. 2, each of the holes 24a, 24b, 25, and 26a provided in the side wall of the developing case 8.

26b and 26c are also symmetrically provided on the side wall of the developing case on the opposite side, and the bearing member 20 shown in FIG. 4 is similarly attached symmetrically on the side wall of the developing case on the opposite side.

〔Effect of the invention〕

The present invention is as described above, and as is clear from the description of the illustrated embodiment, according to the present invention, the positioning means for the doctor blade and the guide plate is integrated with a bearing member that pivotally supports both ends of the magnet roller. In other words, by providing positioning means for the doctor blade and ATC that regulate the amount of developer supplied to the photoreceptor, as well as the guide plate that guides the developer to the doctor blade, it is possible to eliminate the gap spacer like the conventional one, that is, the long width. You can easily and accurately adjust the gap between the doctor blade and the magnetic roller sleeve, or even between the guide plate and the magnetic roller sleeve, without using gap spacers that are inefficient, such as adjusting the left, right, and center three locations of the doctor blade and guide plate. The developer can be assembled while maintaining the

[Brief explanation of the drawing]

1 to 5 show an embodiment of the developing device for an electrophotographic printing machine according to the present invention, FIG. 1 is a longitudinal sectional view showing the internal structure of the developing device 3, and FIG. 2 is a longitudinal sectional view showing the inside of the developing device 3. FIG. 3 is a perspective view of the bearing member indicated by the reference numeral 20 in FIG. 1, and FIG. A' sectional view, Figure 5 is the 1st
A perspective view of a guide plate indicated by reference numeral 12 in the figure, and FIGS. 6 and 7 show a conventional developing device 1 during operation of an electrophotographic printing machine.
FIG. 8 is a vertical cross-sectional view showing the internal structure of the conventional developing device 1 shown in FIGS. 6 and 7 (examples of different behaviors of the developer 9). FIG. DESCRIPTION OF SYMBOLS 1... Developing device, 2... Hopper, 3... Developing device, 4... Toner, 8... Developing case, 11... Magnet roller, 12... Guide plate, 13...・
Doctor blade, 15... automatic toner concentration sensor (ATC), 20... bearing member, 20a... doctor blade positioning section, 20b... guide plate positioning section. Tea 1 Mouth 30th Ward 4/I Z2) δ qth diagram?

Claims (1)

[Claims] 1. A magnetic roller that supplies developer to the photoreceptor;
The automatic toner density sensor that automatically detects the toner density, the doctor blade that regulates the amount of developer supplied to the photoreceptor via the magnetic roller, and the sensor head and doctor blade of the automatic toner density sensor. 1. A developing device for an electrophotographic printing machine having a guide plate for guiding a developer, characterized in that a means for positioning the doctor blade and the guide plate is provided integrally with a bearing member of the magnetic roller. The developing device of the machine.