JPH06175478A - Developing device - Google Patents

Abstract

PURPOSE:To supply the toner stably, and to obtain the excellent image stably even in the case of using the negative-charged acid toner by forming a toner supplying roller, of which surface is made of an ether-based urethane foam. CONSTITUTION:In a toner supplying device 20, a toner feeding member 22 is rotated to feed the toner 2, which is housed inside a toner supply chamber 21, to a toner reservoir chamber 24 provided with a toner supplying roller 23. The toner supplying roller 23 is rotated to supply the toner, which is fed into the toner reservoir chamber 24, into a developing tank 11 through a porous plate 25. At this stage, in the toner supplying roller 23, a roll part 23b made of an ether-based urethane foam is fitted to the periphery of a rotary shaft 23a made of a metal. Even in the case where the negative-charged acid toner is used, lowering of the strength of the surface of the toner supplying roller 23 is prevented to eliminate the breakdown of a part of the roller 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer, and more specifically, a toner replenishing device for replenishing toner into a developing tank by a toner supply roller. The present invention relates to a developing device provided.

[0002]

2. Description of the Related Art Conventionally, in a developing device used in an image forming apparatus such as a copying machine or a printer, the amount of toner in a developing tank decreases as an image is formed. A toner replenishing device for replenishing the toner is provided, and the toner is replenished into the developing tank from the toner replenishing device.

As such a toner replenishing device, various types have been conventionally used. As one of the toner replenishing devices, a toner supply roller is provided in the toner replenishing device to supply the toner. It has been known that a toner roller is rotated to replenish toner into the developing tank.

Here, when the toner supply roller is provided in the toner replenishing device as described above, conventionally, in order to ensure that the toner supply roller has sufficient durability, it is generally made of metal or resin. The roll portion on the outer circumference of the constituted rotating shaft is made of an ester-based urethane foam having thick fibers and high tensile strength.

However, in the case where the toner supplying roller whose surface roll portion is composed of ester urethane foam is used to replenish the negatively charged acidic toner into the developing tank, the toner is When the supply roller is used at high temperature and high humidity for a long time, hydrolysis is promoted in the roll portion composed of the ester urethane foam on the surface of the toner supply roller, its strength is lowered, and Part of the roller is torn off, making it impossible to stably supply toner to the developing tank, or broken pieces of the toner supply roller are supplied together with toner into the developing tank, which adversely affects image formation. There were problems such as

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems in a developing device in which toner is replenished into a developing tank by a toner supply roller provided in the toner replenishing device. This is an issue.

That is, according to the present invention, in the developing device in which the toner supply roller provided in the toner replenishing device as described above replenishes the toner into the developing tank, the negatively chargeable acidic toner is added. Even when used, the strength of the toner supply roller does not decrease and tear does not occur, and the toner supply roller stably supplies the toner into the developing tank.
Another object is to obtain a good image in a stable manner.

[0008]

According to the present invention, in order to solve the above problems, a developing device in which toner is replenished into a developing tank by a toner supply roller provided in a toner replenishing device. In the above, at least the surface of the toner supply roller is made of ether type urethane foam.

[0009]

In the developing device of the present invention, as the toner supply roller for replenishing the toner into the developing tank as described above, at least the surface thereof is made of ether type urethane foam is used. The toner is replenished in the developing tank.

As described above, when the toner is replenished in the developing tank by using the toner supply roller having at least the surface made of ether type urethane foam, even when the negatively chargeable acidic toner is used, The surface of the toner supply roller is not hydrolyzed.

Therefore, unlike the conventional toner supply roller, the toner supply roller does not have its surface strength lowered and part of the toner supply roller is torn off. As a result, the toner can be stably supplied to the developing tank, and the broken pieces of the toner supply roller are not supplied to the developing tank together with the toner, and the image formation is not adversely affected. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings, and a comparative example will be given. In particular, it is clarified that the negatively charged acidic toner can be stably supplied into the developing tank.

In the developing device in this embodiment,
As shown in FIG. 1, a developing sleeve 13 having a magnet roller 12 therein is provided rotatably in a developing tank 11 containing a developer so as to face the image carrier 1, and the developing sleeve 13 is A bucket roller 14 for supplying a developer to the developing sleeve 13 is rotatably provided at a position opposite to the image carrier 1 via the sleeve 13.

Further, above the bucket roller 14 thus provided in the developing tank 11, the developing tank 11 is provided.
A toner replenishing device 20 for replenishing the toner 2 is provided therein.

In the toner replenishing device 20, the toner 2 is accommodated in the toner replenishing chamber 21, a toner feeding member 22 is provided which rotates in the toner replenishing chamber 21, and the toner feeding member 22 is rotated. Then, the toner 2 contained in the toner supply chamber 21 is sent from the toner supply chamber 21 to the toner reservoir chamber 24 provided with the toner supply roller 23.

In this embodiment, as the toner supply roller 23, an ether type urethane foam (manufactured by INOAC Co., Ltd.
The toner supply roller 23, which is provided with the roll portion 23b made of CF-17), is used.
Is brought into contact with a perforated plate 25 provided at a toner supply port for supplying the toner 2 to the developing tank 11 and bites into the biting part 26 by about 1 to 1.5 mm to rotate in the toner reservoir chamber 24. I made it possible.

Then, the toner supply roller 23 provided in the toner storage chamber 24 is rotated in this way, and is fed into the toner storage chamber 24 from the toner replenishing chamber 21 by the toner feeding member 22 as described above. The toner 2 is passed through the perforated plate 25 provided at the toner supply port to the developing tank 11.
I tried to replenish inside.

Further, in this embodiment, a toner density detecting section 16 is provided at a position further away from the image carrier 1 than the bucket roller 14 provided in the developing tank 11, and the toner density detecting section 16 is provided in the toner density detecting section 16. Toner 2 in developer
A toner concentration detection sensor 15 for detecting the concentration of the toner is provided.

Then, a part of the developer in the developing tank 11 is introduced into the toner concentration detecting section 16 by the rotation of the bucket roller 14 and the concentration of the toner 2 in the developer thus introduced is determined as the toner. Concentration detection sensor 1
After being detected by 5, the developer is returned to the inside of the developing tank 11 by the developer conveying screw 17 provided in the toner concentration detecting section 16.

Next, the case where development is performed using the developing device in this embodiment will be specifically described.

In the developing device in this embodiment,
As described above, the bucket roller 14 provided in the developing tank 11 is rotated, the developer accommodated in the developing tank 11 is supplied to the developing sleeve 13 by the bucket roller 14, and the developer thus supplied is supplied. Is held on the developing sleeve 13 by the magnetic force of the magnet roller 12 provided inside the developing sleeve 13.
With the rotation of 3, the developer is sent to the image carrier 1 side. In addition, while the developer is being sent to the image carrier 1 in this way, the amount of the developer on the developing sleeve 13 is regulated by the regulating member 18, and thereafter, the developing sleeve 1
The developer is guided to the image carrier 1 by 3, and the toner 2 is applied from the developing sleeve 13 to the electrostatic latent image portion formed on the image carrier 1.

Further, as the bucket roller 14 rotates, a part of the developer contained in the developing tank 11 as described above is sent to the toner concentration detecting section 16 to determine the concentration of the toner 2 in the developer. The toner concentration detecting sensor 15 provided in the toner concentration detecting unit 16 detects the
This developer was returned to the inside of the developing tank 11 by the developer transport screw 17.

Here, the toner concentration detecting sensor 1 described above is used.
When the density of the toner 2 detected by 5 is lower than a predetermined value, the toner supply roller 23 provided in the toner replenishing device 20 is rotated to move the toner from the toner replenishing chamber 21 into the toner reservoir chamber 24. Toner 2 sent to
The toner supply roller 23 supplies the toner to the developing tank 11 through the perforated plate 25 provided at the toner supply port.

Comparative Example 1 In the developing device of this comparative example, only the toner supply roller 23 provided in the toner replenishing device 20 is changed in the developing device of the above embodiment shown in FIG.

In the developing device of Comparative Example 1, as the toner supply roller 23, the roll portion 23b provided on the outer periphery of the metal rotating shaft 23a is an ester urethane foam (MF-20 manufactured by INOAC). The configured one was used.

Comparative Example 2 In the developing device of this comparative example, only the toner supply roller 23 provided in the toner replenishing device 20 is changed in the developing device of the above embodiment shown in FIG.

In the developing device of Comparative Example 2, as the toner supply roller 23, the roll portion 23b provided on the outer periphery of the metal rotating shaft 23a is an ester urethane foam (SP-20 manufactured by INOAC). I used the one that consisted of.

Next, each of the toner supply rollers 2 used in each of the developing devices of Examples and Comparative Examples 1 and 2 described above.
With respect to No. 3, the influence in the case of using the following four types of toners A to D was examined.

Here, in the toner A, styrene-
Acrylic resin (weight average molecular weight Mw = 200,000, number average molecular weight Mn = 9000, Tg = 57 ° C.) and a charge control agent shown in the following (Chemical formula 1) (Orient Chemical Co., S34)
And carbon black and a wax composed of low molecular weight polypropylene (manufactured by Sanyo Kasei Co., Ltd., Viscole 550P) in the proportions shown in Table 1 below.

In Toner B, a polyester resin (weight average molecular weight Mw = 200,000, number average molecular weight Mn = 1
0000, Tg = 59 ° C.), a charge control agent (S34 manufactured by Orient Chemical Co., Ltd.) shown below (Chemical formula 1), carbon black, and a wax composed of low molecular weight polypropylene (manufactured by Sanyo Kasei Co., Viscole 550P). The following table 1
It was manufactured by using it at the ratio shown in.

In the toner C, a polyester resin (weight average molecular weight Mw = 200,000, number average molecular weight Mn = 1
0000, Tg = 59 ° C.), a charge control agent (S34 manufactured by Orient Chemical Co., Ltd.) shown below (Chemical formula 1), carbon black, and a wax composed of low molecular weight polypropylene (manufactured by Sanyo Kasei Co., Viscole 550P). , And ferrite in the proportions shown in Table 1 below.

In Toner D, styrene-acrylic resin (weight average molecular weight Mw = 200,000, number average molecular weight M
n = 9000, Tg = 57 ° C.), a charge control agent (NBEX manufactured by Orient Chemical Co., Ltd.) shown in (Chemical Formula 2) below, a wax composed of carbon black and low molecular weight polypropylene (Viscole 550P manufactured by Sanyo Chemical Co., Ltd.). ) And ferrite in the proportions shown in Table 1 below.

[0033]

[Chemical 1]

[0034]

[Chemical 2]

[0035]

[Table 1]

For each of the above toners A to D,
SiO ₂ was added in the proportions shown in Table 2 below. Then, the particle diameter and pH of each of the toners A to D were measured, and the results are also shown in Table 2. The pH of each of the toners A to D was measured while the toners A to D were dispersed in a mixed liquid of water: isopropyl alcohol = 6: 10.

[0037]

[Table 2]

Then, in examining the influence of each of the toners A to D on each toner supply roller 23 used in each of the developing devices of Examples and Comparative Examples 1 and 2, the above toner supply rollers are examined. No. 23, an ether type urethane foam piece (CF-17 manufactured by INOAC), an ester type urethane foam piece (MF-20 manufactured by INOAC), and an ester type urethane foam piece (made by INOAC) , SP-20) in each of the above-mentioned toners A to D, respectively, while being left at a temperature of 55 ° C. and a humidity of 95% under high temperature and high humidity, the strength of each urethane foam piece is reduced by 50%. The time required was measured. The strength of each urethane foam piece was measured based on the JIS standard vulcanized rubber physical test method (JIS K6301).

FIG. 2 shows the relationship between the time required for the strength of each urethane foam piece measured as described above to decrease by 50% and the pH of each of the toners A to D. In the figure, the case of an ether type urethane foam piece (CF-17 manufactured by INOAC) is indicated by □ and a solid line,
Ester-based urethane foam pieces (MF manufactured by INOAC, MF
The case of -20) is indicated by a circle and a broken line, and the case of an ester-based urethane foam piece (SP-20 by INOAC CORPORATION) is indicated by a triangle and a dashed line.

As is clear from the results shown in FIG.
The same ether type urethane foam piece (manufactured by INOAC Co., Ltd., which is the same as that used for the toner supply roller in the above embodiment)
CF-17) showed almost no deterioration in any of the toners A to D and was stable for a long period of time with respect to the toner of any pH, whereas the toner supply roller in Comparative Example 1 Ester-based urethane foam pieces (MF-20, manufactured by INOAC) that are the same as those used for
In the same ester-based urethane foam piece (SP-20 manufactured by INOAC Co., Ltd.) as used for the toner supply roller in Comparative Example 2, the lower the pH of the toner, the more strongly the acidic toner is used. It turns out that the deterioration is accelerated.

Next, in each of the developing devices of the above-mentioned Examples and Comparative Examples 1 and 2, the above-mentioned acidic toner A is replenished by the above-mentioned respective toner supply rollers, and 60
A printing durability test was performed on ten thousand sheets, and the weight of each urethane foam fragment that was torn from each toner supply roller and mixed into the developer was measured.

Here, in carrying out the printing durability test, a copy chart in which the ratio of the black portion to the paper surface is 6% is used, the system speed is set to 250 mm / sec, and the copy speed is set to 40 sheets / min in the A4 lateral direction. , Temperature 30 ℃, humidity 8
The test was conducted under the condition of 5%.

Then, at the time when an appropriate number of printable sheets was reached during the above-mentioned printing durability test, the above-mentioned Examples and Comparative Examples 1 and 2 were performed.
In each of the developing devices, the developer in each developing tank is taken out, the developer thus taken out is passed through a 500 μm mesh sieve, and is cut off from each of the toner supply rollers at each of the number of printed sheets. The weight of each urethane foam fragment mixed in the developer was measured, and the result is shown in FIG. In the figure, the case of the developing device in the example is indicated by □ and the solid line, the case of the developing device in Comparative Example 1 is indicated by ◯ and the broken line, and the case of the developing device in Comparative Example 2 is indicated by Δ and the one-dot chain line. .

As is clear from the results shown in FIG.
In the developing device of the above embodiment, the number of printing endurance tests is 60.
Even when the number of sheets reached 10,000, the fragments of the ether type urethane foam used for the toner supply roller were hardly mixed in the developer, whereas in the developing devices of Comparative Examples 1 and 2, the toner was Fragments of each ester-based urethane foam used for the supply roller are often mixed in the developer as the number of printed sheets increases.

[0045]

As described above in detail, in the developing device according to the present invention, when the toner supply roller provided in the toner replenishing device replenishes the toner in the developing tank, at least the toner supply roller is used. The toner supply roller is used to replenish the toner into the developing tank, so that the surface of the urethane urethane foam is used to supply the toner even when negatively charged acidic toner is used. The surface of the roller was not hydrolyzed and the strength of the surface was not reduced.

As a result, in the developing device according to the present invention, even when the toner supplying roller provided in the toner replenishing device replenishes the negatively charged acidic toner into the developing tank, This toner supply roller allows the toner to be stably supplied to the developing tank without the part of the roller being torn off, and the broken pieces of the toner supply roller can be removed together with the toner. A good image can be stably obtained without being adversely affected on image formation by being supplied into the developing tank.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a developing device according to an embodiment of the present invention.

FIG. 2 shows the influence of toners A to D on each urethane foam used in the toner supply roller in each developing device of Examples and Comparative Examples 1 and 2 of the present invention, and the strength of each urethane foam is reduced by 50%. FIG. 6 is a diagram showing the relationship between the time required for and the pH of the toner.

FIG. 3 is a result of a printing durability test conducted while replenishing toner A with a toner supply roller in each developing device of Examples and Comparative Examples 1 and 2 of the present invention, and as a result, fragments of each urethane foam were found in the developer. FIG. 6 is a diagram showing the relationship between the mixed amount and the number of printed sheets.

[Explanation of symbols]

 1 Image Carrier 2 Toner 20 Toner Replenishing Device 23 Toner Supply Roller 23b Roll Unit

Claims (1)

[Claims] 1. A developing device provided with a toner replenishing device for replenishing toner into a developing tank by means of a toner supplying roller, wherein at least the surface of the toner supplying roller is made of ether type urethane foam. Developing device.