JP2001051497A - Developing device and color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good image provided with sufficient image density in a developing device where a toner carrier is rotated so that it is moved from below to above in a developing range faced with an image carrier. SOLUTION: In the developing device where developing is carried out by rotating the roll-shaped toner carrier 21 so that it is moved from below to above in a developing range faced with an image carrier 10, a receiving member 23 is installed below a toner feeding member 25 feeding the toner 't' to the toner carrier 21 and a toner retaining part 24 is formed, a toner feeding member 22 provided with a blade member 22a is rotated and the blade member 22a is made to incline downward toward the toner retaining part 24 in a position where the toner 't' contained in a device main body 20 is fed to the toner retaining part 24 by the blade member 22a.

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 a color image forming a color image by storing toners of different colors in such a developing device. Related to the forming device,
In particular, when only toner is used as the developer and the toner is guided to the developing area facing the image carrier by the toner carrier in the form of a roller, the development is performed in the developing area facing the image carrier. The toner carrier is rotated so as to move upward from, and a regulating member is provided below the toner carrier so that the amount of toner conveyed to the developing area by the toner carrier is regulated by the regulating member. The present invention relates to a developing device and a color image forming apparatus using such a developing device.

[0002]

2. Description of the Related Art Conventionally, as a developing device used in an image forming apparatus such as a copying machine or a printer, in addition to a two-component developing system using a toner and a carrier as a developer, a developing method using no carrier is used. 1 using only toner
A component developing system is known.

[0003] Here, a developer using only toner as a developer 1
As shown in FIG. 1, for example, as shown in FIG. 1, a toner t contained in a container 1 a of a device main body 1 is sent to a roller-shaped toner supply member 3 by a toner feed member 2. The toner supply member 3 is rotated to supply the toner t to the toner carrier 4 in the form of a roller. The toner t thus supplied is conveyed by the rotation of the toner carrier 4 and the toner carrier 4 is rotated. The regulating member 5 is pressed against the surface of the toner carrier 4 to regulate the amount of the toner t conveyed by the toner carrier 4 and to frictionally charge the toner t. The one in which t is guided to a development area facing the image carrier 6 by the toner carrier 4 to perform development has been used.

Here, in the conventional developing device, as shown in FIG. 1, in the developing region where the toner carrier 4 and the image carrier 6 are opposed to each other, the toner carrier 4 and the image carrier 6 are respectively positioned upward. Was rotating to move downward from

However, depending on the type of image forming apparatus, it may be necessary to move the above-described image carrier upward from below in the developing area. In particular, a plurality of developing apparatuses are provided with toners of different colors. In a color image forming apparatus provided with an intermediate transfer member for transferring a toner image formed on an image carrier in an overlapping manner when forming a color image by housing the image carrier, the image carrier is required to be compact. It was sometimes necessary to move the developing area upward from below.

Here, when the image carrier is moved upward from below in the developing area, the toner carrier is rotated so as to move downward from above in the developing area as described above. When the body and the image carrier are brought into contact with each other to develop the toner, the toner accumulates in an upstream portion where the toner carrier comes into contact with the image carrier, and the toner spills to the outside or fog occurs on the formed image. In the case where development is performed without bringing the toner carrier and the image carrier into contact with each other, there is a problem that a leak easily occurs between the toner carrier and the image carrier.

In recent years, Japanese Patent Application Laid-Open No. 9-24
As described in Japanese Patent Application Laid-Open No. 4406 and Japanese Patent Application Laid-Open No. 10-171226, when the image carrier moves upward from below in a development area where the toner carrier and the image carrier face each other, the toner carrier is The toner carrier is rotated so as to move upward from below in the region, and after the toner carrier is supplied from a roller-shaped toner supply member to the toner carrier, the toner on the downstream side in the rotation direction of the toner carrier is supplied by the toner supply member. There has been proposed a developing device in which the toner supplied to the toner carrier at the lower side of the carrier is regulated by a regulating member.

Here, in the developing devices disclosed in these publications, a toner feeding member provided in the main body of the apparatus is rotated to send toner to a toner supplying member, and the toner is supplied from the toner supplying member to a toner carrier. I was trying to do it.

However, simply rotating the toner feed member and feeding the toner to the toner supply member in this manner cannot supply a sufficient amount of toner from the toner supply member to the toner carrier. When the amount of toner in the main body is reduced, the amount of toner guided to the toner supply member is reduced, and a sufficient amount of toner is not supplied to the toner carrier. There is a problem that the amount of toner to be removed is reduced and the density of an image to be formed is reduced. In particular, when a solid image is formed, a reduction in density and blurring occur.

For this reason, it is conceivable to increase the amount of toner to be sent to the toner supply member by increasing the rotation speed of the toner feed member. There is a problem that it is difficult to detect the remaining amount of toner in the main body by an optical sensor, and a high-powered driving device is required in order to increase the rotation speed of the toner feeding member. There is a problem that a mechanism for increasing the speed is required.

[0011]

SUMMARY OF THE INVENTION According to the present invention, when a toner is guided by a rotating toner carrier to a developing region facing the image carrier and development is performed, the developing region facing the image carrier faces upward from below. And a regulating member provided below the toner carrier to regulate the amount of toner conveyed to the developing area by the toner carrier. It is an object of the present invention to solve the above-mentioned problem in the above.

That is, according to the present invention, in the developing device as described above, the toner feeding member provided in the main assembly of the apparatus is rotated to send the toner to the toner supplying member, and the toner is supplied from the toner supplying member to the toner carrier. In supplying the toner, a sufficient amount of toner is stably supplied from the toner supply member to the toner carrier, and a sufficient amount of toner is guided to the developing area by the toner carrier to form a solid image. It is another object of the present invention to obtain a good image having a sufficient image density without causing a decrease in density or blurring.

[0013]

In the developing device according to the present invention, in order to solve the above-mentioned problems, the roller-shaped toner carrier is moved upward from below in a developing area opposed to the image carrier. To supply toner from the toner supply member to the toner carrier, and the amount of toner conveyed by the toner carrier by the regulating member at a position downstream of the toner supply member in the rotation direction of the toner carrier. In a developing device that conducts development by guiding the toner to a development area by a toner carrier, a toner feed member having a blade member is rotatably provided in the main body of the device, and a toner feed member is provided below the toner supply member. The apparatus main body is provided by providing a toner retaining portion for retaining the toner supplied to the toner carrier by providing a receiving member, and rotating the toner feeding member. When the toner contained in the toner feeding member is guided to the toner retaining portion by the blade member, the blade member provided on the toner feeding member is inclined downward toward the toner retaining portion at a position where the toner is supplied to the toner retaining portion. It is.

Then, as in the developing device according to the present invention, the toner carrier is rotated so as to move upward from below in a developing area opposed to the image carrier, and is located upstream of the regulating member in the rotational direction of the toner carrier. In supplying the toner from the toner supply member to the toner carrier at the position, a receiving member is provided below the toner supply member, and a toner retaining portion for retaining the toner supplied to the toner carrier is provided, and the blade member is provided. When the provided toner feed member is rotated in the apparatus main body and the toner contained in the apparatus main body is guided to the toner retaining section by the blade member, the blade member is positioned at a position where the toner is supplied to the toner retaining section. When the toner is conveyed by the blade member so as to be inclined downward toward the stagnant portion, the toner conveyed by the blade member is moved along the toner stagnant portion along the blade member. Flow, so that a sufficient amount of toner is accumulated is supplied to the toner retention part.

[0015] The toner stagnated in the toner stagnating portion is supplied to the toner carrier by the toner supply member, so that a sufficient amount of toner can be supplied without increasing the rotation speed of the toner feed member. Is supplied to the toner carrier by the toner supply member.
Even when the amount of toner in the apparatus main body is reduced, a sufficient amount of toner is stably guided to the developing area by the toner carrier and used for development, and even when a solid image is formed, the density may decrease. The occurrence of burrs is suppressed, and an image having a sufficient image density can be obtained.

Further, in the developing device according to the present invention, at a position where the toner is supplied to the toner retaining portion, the inclination angle θ of the blade member inclined downward toward the toner retaining portion is determined by the toner. When the angle of repose is set to be equal to or larger than the angle of repose, the toner on the blade member surely flows into the toner retaining portion, and a sufficient amount of toner is retained in the toner retaining portion.

In the developing device according to the present invention, the blade member has a flexural modulus X (MPa) of 2000 to 5000 MPa and a thickness d (mm) of 0.05 to 0. When the distance is set to 25 mm and the condition of 150 ≦ X · d ≦ 1000 is satisfied, when the toner feeding member is rotated as described above to supply the toner to the toner retaining portion by the blade member, the blade The member is largely bent by the weight of the toner, so that the toner on the blade member is prevented from falling from the blade member before being guided to the toner retaining portion, and a sufficient amount of toner is guided to the toner retaining portion by the blade member. At the same time, the blade member is appropriately elastically deformed and softly contacts the apparatus main body, so that a frictional noise or the like during rotation is reduced.

In the developing device according to the present invention, at the position where the toner is supplied to the toner retaining portion, the blade member is moved from the receiving member to the toner retaining portion by a distance of 10 to 20 mm. When the blade member is made to protrude within the range, the blade member does not significantly deform due to the weight of the toner and the like, and even when the blade member is deformed, the tip of the blade member reaches the position of the receiving member. Thus, the toner on the blade member is reliably supplied to the toner retaining section.

Further, in the developing device according to the present invention, the blade member is brought into contact with the rotating blade member at a position above the position where the blade member supplies the toner to the toner retaining portion, and the blade member contacts the rotating blade member. Is provided, the toner remaining on the blade member without being supplied to the toner retaining portion is scraped off from the blade member by the scraping member and supplied to the toner retaining portion. , And more toner is supplied to the toner accumulation section. In the case where a scraping member that scrapes off the toner on the blade member is provided as described above, the toner on the blade member is efficiently scraped off by the scraping member. It is desirable that the scraping member begin to contact the blade member.

In the color image forming apparatus according to the present invention, a plurality of developing devices accommodating toners of different colors, and the toner images formed on the image carrier by these developing devices are transferred in a superimposed manner. In a color image forming apparatus provided with an intermediate transfer member, the above-described developing device of the present invention is used.

Each of the developing devices in the color image forming apparatus is provided with a developing device according to the present invention in which the toner carrier rotates so as to move upward from below in the developing region facing the image carrier. With the use of, it is possible to form an image having a sufficient image density by moving the image carrier from the bottom to the top in the development area, and, corresponding to the configuration of the color image forming apparatus,
The device can be made compact.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings.

In the developing device according to this embodiment,
A toner carrier 21 is provided so as to face the image carrier 10 with a small space therebetween, and the toner carrier 21 and the image carrier 10 are rotated in opposite directions to rotate the toner carrier 21 and the image carrier 10. The toner carrier 21 and the image carrier 10 are respectively moved upward from below in the development region where.

Further, in this developing device, the toner t is stored in the storing portion 20a of the device main body 20, and the toner feeding member 22 provided with the blade member 22a is rotatably provided.

Then, the toner feed member 22 is rotated, and the blade member 22a of the toner feed member 22 is rotated.
Thus, the toner t stored in the storage section 20a is supplied to the toner retaining section 24 provided with the receiving member 23.

Here, in the developing device according to this embodiment, as shown in FIG. 3, the blade member 22a is attached to the end face of the rotating member 22b of the toner feeding member 22 by the rotating member 2.
At a position where the blade member 22a supplies the toner t to the toner retaining portion 24 by the blade member 22a, the blade member 22a moves downward toward the toner retaining portion 24 at a predetermined inclination angle θ. The blade member 22a is inclined and the tip of the blade member 22a projects from the receiving member 23 toward the toner retaining portion 24. In the developing device of this embodiment, the toner feeding member 22
The blade member 22a is attached to the end surface of the rotating member 22b at a substantially right angle to the rotating member 22b.
As shown in FIG. 7, the blade member 22a can be attached so as to extend along the rotating member 22b.

At the position where the toner t is supplied to the toner retaining section 24 as described above, the blade member 22a
Is inclined downward at a predetermined inclination angle θ toward the toner accumulating portion 24, the toner t on the blade member 22a is moved along the downwardly inclined blade member 22a.
4 and a sufficient amount of toner t
Will be stagnated.

In the toner retaining section 24 where the toner t is retained in this way, the roller-shaped toner supply member 25 having the foamed elastic layer 25a on the outer peripheral portion is brought into contact with the toner carrier 21. Is provided.

Then, the toner supply member 25 is rotated in the same direction as the toner carrier 21 so that the toner supply member 25 and the toner carrier 21 are moved in the opposite direction at the portion where they come into contact. The toner t is supplied from the member 25 to the toner carrier 21.

Further, one end of a plate-like pre-charging member 26 made of a conductive material is attached to the receiving member 23, and this pre-charging member 26 is connected to the toner supply member 25.
At a position downstream of the toner supply member 25 in the rotation direction of the toner carrier 21, the front end of the pre-charging member 26 is attached to the toner carrier 21. 21 are contacted with an appropriate linear pressure along the axial direction.

Then, the toner t supplied to the toner carrier 21 is pre-charged by contact with the pre-charging member 26, and the toner t thus pre-charged is held on the toner carrier 21 by electrostatic force. I have to.

The lower part of the toner carrier 21 downstream of the tip end of the pre-charging member 26 in the rotation direction of the toner carrier 21 extends toward the upstream side in the rotation direction of the toner carrier 21. Plate-shaped regulating member 27
Is brought into contact with the toner carrier 21 so as to have an appropriate gap with the tip of the pre-charging member 26, and the toner t held by the toner carrier 21 by the electrostatic force as described above is regulated by the regulating member. 27. In this case, since the toner t is held on the toner carrier 21 by the electrostatic force as described above, the toner t is prevented from falling away from the toner carrier 21 before being guided to the regulating member 27, and is sufficiently reduced. A large amount of toner t
Thereby, it is guided to the position of the regulating member 27.

The regulating member 27 removes the excess toner t from the toner carrier 21 to regulate the amount of the toner t conveyed to the developing area and to regulate the amount of the toner t.
Is charged. Note that this regulating member 27
The extra toner t released from the toner carrier 21 is guided downward through the gap, and is returned to the storage section 20a by a return roller 28 provided below the toner t.

Next, the toner t regulated by the regulating member 27 and charged as described above is transferred to the toner carrier 2.
1 to the developing area facing the image carrier 10,
In this development area, the toner carrier 21
And the image carrier 10 are respectively moved upward from below, and a developing bias voltage in which an AC voltage is superimposed on a DC voltage is applied from a developing bias power supply 29 to the toner carrier 21 so that the toner carrier 21 and the image carrier are An oscillating electric field is applied between the image bearing member 10 and the electrostatic latent image formed on the image bearing member 10 to supply toner t from the toner bearing member 21 to perform development. In this embodiment,
As described above, the development is performed with the toner carrier 21 and the image carrier 10 opposed to each other at a small interval in the development area, but the toner carrier 21 and the image carrier 10 are brought into contact with each other in the development area. It is also possible to cause the development.

After developing the electrostatic latent image formed on the image carrier 10 as described above, the toner carrier 2
The toner t remaining on the toner carrier 1 is returned to the apparatus main body 20, and at a position where the toner t remaining on the toner carrier 21 is returned to the apparatus main body 20, the sealing material 32 is pressed against the toner carrier 21 by the cushion material 31. Seal material 3
2, a voltage for removing the toner t is applied from the power supply 33 for removing the toner, so that the toner t remaining on the toner carrier 21 is removed.

After the toner t remaining on the toner carrier 21 is neutralized, the toner t remaining on the toner carrier 21 is reversed at the portion where the toner carrier 21 comes into contact as described above. The toner is separated from the toner carrier 21 by the toner supply member 25 that moves in the direction, and is mixed with the toner t in the toner retaining section 24, and new toner t is supplied from the toner supply member 25 to the toner carrier 21 as described above. Let it be supplied.

Here, when the toner supply member 25 is moved in the direction opposite to the toner carrier 21 at the portion where the toner carrier 21 contacts as described above, the toner
5 is moved in the same direction as the toner carrier 21, only the toner t having a large particle diameter is detached from the toner carrier 21, and the toner t having a small particle diameter does not remain. 21 small toner t
The toner supply member 25 also ensures that the toner supply member 25 is separated from the toner carrier 21. For this reason, a large amount of the toner t having a small particle diameter is first used for development, and the ratio of the toner t having a large particle diameter in the storage portion 20a gradually increases.
The quality of the formed image does not change.

Next, in the developing device shown in FIG. 2, the toner feed member 22 is rotated as described above, and the toner t stored in the storage portion 20a is received by the blade member 22a of the toner feed member 22. When the toner 23 is supplied to the toner retaining portion 24 provided with the member 23, the state of the blade member 22a provided on the toner feeding member 22 is changed, and the inclination angle θ of the blade member 22a at the position where the toner t is supplied to the toner retaining portion 24. An experiment in which the developing device is changed will be clarified with reference to comparative examples to show that the developing device of the embodiment of the present invention is superior.

(Examples 1 to 7 and Comparative Examples 1 to 3) In the developing devices of Examples 1 to 6 and Comparative Example 1, as the toner feeding member 22, as shown in FIG. In the developing devices of Example 7 and Comparative Examples 2 and 3, as the toner feeding member 22, as shown in FIG. A blade to which the blade member 22a is attached so as to extend along the rotating member 22b is used. The blade member 22a has a flexural modulus X of 3000 MPa and a thickness d of 0.18.
An 8 mm-thick polyethylene terephthalate product was used.

In Examples 1 to 7 and Comparative Examples 1 to 3, at the position where the toner t is supplied to the toner accumulating portion 24 by the blade member 22a of the toner feeding member 22, the blade member 22a Retention part 2
The inclination angle θ inclined toward 4 was changed, and the following Table 1 was used.
As shown in FIG.
°, 27 ° in Example 3, 25 ° in Example 4, 18 ° in Example 5, 10 ° in Example 6, and 12 ° in Example 7.
°, -5 ° in Comparative Example 1, 0 ° in Comparative Example 2, Comparative Example 3
In the position where the toner t is supplied to the toner retaining portion 24, the length l of the tip end of each blade member 22a projecting from the receiving member 23 toward the toner retaining portion 24 is 2 mm. Set to. Note that the above inclination angle θ
+ And-indicate the case where the blade member 22a inclines downward toward the toner retaining portion 24, and the case where the blade member 22a inclines upward toward the toner retaining portion 24.

In each of the developing devices of Examples 1 to 7 and Comparative Examples 1 to 3, the rotation speed of each of the toner feeding members 22 is set to 1 rps, and the blade member provided on the toner feeding member 22 is rotated. The toner t is supplied to the toner stagnation section 24 by 22a.

Examples 1 to 7 and Comparative Example 1
In the developing devices of (1) to (3), a photosensitive drum having a diameter of 30 mm is used as the image carrier 10, and a toner carrier having a diameter of 16 mm is used as the toner carrier 21. The image carrier 10 and 200
The toner carrier 21 and the image carrier 10 are rotated in the opposite directions so that the toner carrier 21 and the image carrier 10 are rotated in opposite directions, so that the toner carrier 21 and the image carrier 10 are opposed to each other. The body 21 and the image carrier 10 are moved upward from below, and the peripheral speed of the image carrier 10 and the peripheral speed of the toner carrier 21 are each set to 160 mm /
s.

As the toner supply member 25, an elastic layer 25a made of urethane foam having a standard cell diameter of 300 μm and an Asker F hardness of 60 ° and a thickness of 2.5 mm formed on the outer peripheral portion is formed. The toner supply member 25 is pressed against the toner carrier 21 so that the dent amount becomes 0.6 mm. In this state, the toner supply member 25 is pressed at a peripheral speed of 300 mm / s.
1 so that the toner supply member 25 and the toner carrier 21 are moved in the opposite direction at a portion where the toner supply member 25 comes into contact with the toner supply member 25, and the toner t is supplied from the toner supply member 25 to the toner carrier 21. At the same time, the toner t returned to the apparatus main body 10 by the toner carrier 21 is separated from the toner carrier 21. The above Asker F hardness is a value measured by a rubber hardness meter (manufactured by Asker: rubber hardness meter F type).

The pre-charging member 26 is made of a SUS plate, and the regulating member 27 is also made of a SUS plate having a thickness of 0.3 mm. And a negatively chargeable toner having a weight average particle diameter of 8.0 μm and a repose angle of 30 ° was used as the toner t.

Then, the tip of the pre-charging member 26 is brought into contact with the toner carrier 21 to pre-charge the toner t supplied to the toner carrier 21, and the toner t is electrostatically charged on the toner carrier 21. The toner t is guided to the regulating member 27 by the toner carrier 21,
The regulating member 27 regulates the amount of the toner t guided to the developing area, and frictionally charges the toner t. The toner t is guided to the developing area facing the image carrier 10 by the toner carrier 21.

The surface potential of the image carrier 10 is-
While a solid electrostatic latent image of 50 V is formed, the developing bias power supply 29
The peak-to-peak value Vpp is 16 at a DC voltage of -400V.
A developing bias voltage Vb on which an AC voltage having a frequency of 2 kHz at 00 V is superimposed is applied, and a toner t is supplied from the toner carrier 21 to the above-described electrostatic latent image portion formed on the image carrier 10, and each A solid image was formed.

Then, solid images were continuously formed in this way, and the solid images were evaluated on the fifth and tenth sheets, respectively. When a solid image with a constant image density was obtained, Table 1 below shows the case where the image density was slightly reduced, and the case where the image density was greatly reduced was x.

[0048]

[Table 1]

As is apparent from the result, the rotating member 2
In the toner feeding member 22 in which the form of the blade member 22a attached to the second member 2b is any of the forms of FIGS. 3 and 4, the blade member 22a is connected to the toner storing section 24 at the position where the toner t is supplied to the toner storing section 24. Each of the developing devices of Examples 1 to 7 in which the blade member 22a is inclined horizontally or upward toward the toner retaining portion 24 is a developing device of Comparative Examples 1 to 3. In comparison with the above, the decrease in the density of the solid image was suppressed, and an image having a sufficient image density was obtained. In particular,
At the position where the toner t is supplied to the toner retaining section 24,
In the developing devices of the first and second embodiments in which the inclination angle θ at which the blade member 22a inclines downward toward the toner retaining portion 24 is 30 ° or more, which is the repose angle of the toner t, ten solid images are continuously formed. Even when the image was formed, a solid image having a constant image density was obtained.

Next, as shown in Table 2 below, the blade member 22a of the toner feeding member 22 has a flexural modulus X of 1500 to 5500 MPa and a thickness d of 0.038 to
What was changed in the range of 0.300 mm was used.

Then, as shown in FIG. 3, such a blade member 22a is attached so as to be substantially perpendicular to the end face of the rotating member 22b, and at the position where the toner t is supplied to the toner retaining portion 24, the blade member 22a Is the toner retention section 24
The inclination angle θ of the blade member 22a is set to 30 ° and the tip of the blade member 22a is
, Each projecting toward the toner retaining portion 24 by 2 mm.

Then, the toner feeding member 22 using the blade member 22a as described above is rotated at a rotation speed of 1 rps, and the toner t is supplied to the toner retaining portion 24 by each blade member 22a provided on the toner feeding member 22. Then, the supply performance of the toner t to the toner retaining section 24 and the generation of noise during rotation were examined, and the results are shown in Table 2 below. Here, regarding the performance of supplying the toner t to the toner retaining section 24, the case where the toner t is sufficiently supplied to the toner retaining section 24 is ○, and the case where the toner t is not sufficiently supplied to the toner retaining section 24 is With respect to the noise during rotation, 場合 indicates that the noise was not a problem, and X indicates that the noise was a problem due to the loud noise.

[0053]

[Table 2]

As is apparent from the result, the bending elastic modulus X (MP
a) is in the range of 2000 to 5000 MPa, the thickness d (mm) is in the range of 0.05 to 0.25 mm, and 150 ≦ X · d
When the condition of ≦ 1000 is satisfied, the blade member 2
2a allows the toner t to be sufficiently supplied to the toner stagnation section 24, and noise during the rotation of the toner feeding member 22 is reduced.

On the other hand, if the bending elastic modulus X (MPa) of the blade member 22a decreases or the thickness d (mm) decreases, and the value of X · d becomes less than 150, the blade member 22a Is largely bent by the weight of the toner t, and the toner t on the blade member 22a spills from the blade member 22a before being guided to the toner retaining portion 24, and the blade member 22
a, the toner t is not sufficiently supplied to the toner retaining portion 24, while the bending elastic modulus X (MP
When the value of X · d exceeded 1000 due to the increase in a) or the thickness d (mm), the noise during rotation of the toner feeding member 22 increased.

Further, similarly to the toner feeding member 22 used in the developing device of the third embodiment, the bending elastic modulus X is 3000.
Mpa, blade member 22 having thickness d of 0.188 mm
As shown in FIG. 3, the blade member 22 a is attached to the end surface of the rotating member 22 b at a substantially right angle, and at a position where the toner t is supplied to the toner holding portion 24, the blade member 22 a is directed downward toward the toner holding portion 24. The length l of the tip of the blade member 22a protruding from the receiving member 23 toward the toner retaining portion 24 is set to 0 to 25 mm as shown in Table 3 while the inclination angle θ is set to 27 °. Was changed in the range.

Then, the toner feeding member 22 as described above
Examples 1 to 7 and Comparative Examples 1 to 3 except that
In the same manner as in the case of the developing device, solid images are continuously formed, and the solid images are evaluated on the fifth and tenth sheets, respectively. 、, the case where the image density was slightly reduced was indicated by Δ, and the case where the image density was significantly reduced was indicated by X, as shown in Table 3 below.

[0058]

[Table 3]

As is apparent from the result, the blade member 2
When the length l of the tip of 2a protruding from the receiving member 23 toward the toner retaining portion 24 is set to 0 mm, the blade member 22
When a is bent by the weight of the toner t, the tip of the blade member 22a does not reach the receiving member 23, and
And the toner t was not sufficiently supplied, and the density of the solid image was greatly reduced.

On the other hand, if the tip of the blade member 22a is protruded from the receiving member 23 toward the toner retaining portion 24 by a certain length, even when the blade member 22a is bent by the weight of the toner t, the blade member 22a can be bent. The tip of the blade member 22a reaches the toner stagnation section 24, and the toner t is transferred to the toner stagnation section 2.
4, an image having a sufficient image density can be obtained. In particular, the length l of the tip of the blade member 22 a projecting from the receiving member 23 toward the toner retaining portion 24 is set to 10 to 20 mm. When the range was set, a solid image having a constant image density was obtained even when ten solid images were continuously formed. If the length l of the tip of the blade member 22a protruding from the receiving member 23 toward the toner retaining portion 24 is set to 25 mm, the blade member 22a
Is largely bent by the weight of the toner t, the toner t on the blade member 22a is slightly spilled from the blade member 22a before being guided to the toner retaining portion 24, and the amount of the toner t in the toner retaining portion 24 is reduced. When solid images were continuously formed, the image density was reduced.

(Embodiment 8) In this embodiment, similarly to the developing device of the third embodiment, the flexural modulus X is 300.
Blade member 2 having 0 MPa and thickness d of 0.188 mm
As shown in FIG. 3, as shown in FIG. 3, at the position where the toner t is supplied to the toner accumulating portion 24 by using the toner feeding member 22 attached so as to be substantially perpendicular to the end surface of the rotating member 22 b, The inclination angle θ inclined downward toward the toner retaining portion 24 is set to 27 °, and the length l of the tip of the blade member 22a protruding from the receiving member 23 toward the toner retaining portion 24 is 2 mm. I did it.

In the developing device of this embodiment,
As shown in FIG. 5, the blade member 22a is
A scraping member 33 that comes into contact with the rotating blade member 22a and scrapes off the toner t on the blade member 22a at a position higher than the position where the toner t is supplied to the blade member 22a. The toner t remaining on the member 22a is scraped off from the blade member 22a by the scraping member 33 and supplied to the toner retaining section 24.

In the developing device of this embodiment, solid images are continuously formed in the same manner as in the developing devices of Examples 1 to 7 and Comparative Examples 1 to 3, respectively. The solid image was evaluated on each of the 10th and 10th sheets, and a solid image having a constant image density was obtained, a solid image density was obtained, a slightly reduced image density was obtained, and a large image density was significantly reduced. The results are shown in Table 4 below together with the results of Example 2 described above.

[0064]

[Table 4]

As is apparent from the result, the blade member 2
In the eighth embodiment, a scraping member 33 that contacts the rotating blade member 22a and scrapes off the toner t on the blade member 22a is provided at a position above the position where the toner 2a supplies the toner t to the toner retaining portion 24. In the developing device, the toner t remaining on the blade member 22a without being supplied to the toner retaining portion 24 is scraped off from the blade member 22a by the scraping member 33 and supplied to the toner retaining portion 24. That is, even when ten solid images were continuously formed, a solid image having a constant image density was obtained.

Next, a color image forming apparatus according to an embodiment of the present invention using the developing device shown in the above embodiment will be specifically described with reference to the accompanying drawings.

Here, in the color image forming apparatus according to the first embodiment, as shown in FIG. 4, four developing devices A1 to A4 according to the above embodiment are used.
The three developing devices A1 to A4 contain toners of different colors of yellow, magenta, cyan, and black, and the four developing devices A1 to A4 are held by a rotating holder 40. The positions of A1 to A4 are changed, and the toner carrier 21 in each of the developing devices A1 to A4 is sequentially guided to a position facing the image carrier 10 so that the toner carrier 21 and the image carrier 10 face each other. In the region, the toner carrier 21 and the image carrier 10 move upward from below.

When a color image is formed by the color image forming apparatus of the first embodiment, for example, first, the toner carrier 21 of the first developing device A1 containing yellow toner is replaced with the image carrier. 10 so that the image carrier 10 is rotated,
The surface of the image carrier 10 is uniformly charged by the charging device 41, and the thus-charged image carrier 10 is exposed by the exposure device 42 in accordance with an image signal. An electrostatic latent image is formed on the surface.

Next, in the developing area where the image carrier 10 on which the electrostatic latent image is formed and the toner carrier 21 of the first developing device A1 face each other, the toner carrier 2
1 and the image carrier 10 are respectively moved upward from below, and the yellow toner is supplied from the toner carrier 21 to the electrostatic latent image portion formed on the image carrier 10, and the image carrier 1
At 0, a yellow toner image corresponding to the electrostatic latent image is formed.

The yellow toner image thus formed on the image carrier 10 is transferred to an endless belt-shaped intermediate transfer member 43 stretched over the image carrier 10, and after the transfer, The yellow toner remaining on the image carrier 10 is removed from the image carrier 10 by the cleaning device 44.

Thereafter, the holder 40 is rotated to position the toner carrier 21 of the second developing device A2 containing the magenta toner next so as to face the image carrier 10, and In the same manner as in the case of the first developing device A1, a magenta toner image is formed on the surface of the image carrier 10, and this magenta toner image is transferred to the intermediate transfer member onto which the yellow toner image has been transferred. On the other hand, the magenta toner remaining on the image carrier 10 after the transfer is removed from the image carrier 10 by the cleaning device 44.

Then, the same operation is performed to form a cyan toner image on the surface of the image carrier 10 by the third developing device A3 containing the cyan toner, and the cyan toner image is formed. A black toner image is formed on the surface of the image carrier 10 by the fourth developing device A4 containing the black toner and transferred to the intermediate transfer member 43, and this cyan toner image is transferred to the intermediate transfer member 43 Is transferred to the intermediate transfer member 43, and thus the yellow, magenta, cyan,
The black toner images are transferred to form full-color toner images.

Then, a recording sheet 46 is transferred from a sheet cassette 45 provided below the color image forming apparatus by a feed roller 47 to an intermediate transfer member 43 and a transfer roller 48.
The full color toner image formed on the intermediate transfer member 43 is transferred to the recording sheet 46, and the full color toner image thus transferred on the recording sheet 46 is recorded by the fixing device 49. The sheet is fixed to the sheet 46 and discharged, while the intermediate transfer member 43 is not transferred.
The remaining toner is removed from the intermediate transfer member 43 by the cleaning device 50.

Further, in the color image forming apparatus according to the second embodiment, as shown in FIG. 5, four developing devices A1 to A4 in the above embodiment are used, and these four developing devices A1 to A4 are used. Yellow, magenta, cyan,
The four developing devices A1 to A4 are accommodated in the color image forming apparatus in order from the top while containing toners of different colors of black, and are opposed to the toner carrier 21 in each of the developing devices A1 to A4. The image bearing members 10 are respectively provided in the developing areas where the toner bearing members 21 and the image bearing members 10 face each other.
1 and the image carrier 10 move upward from below.

Further, an endless belt-shaped intermediate transfer member 43 is provided at the opposite side of the developing devices A1 to A4 via the image carrier 10 and is provided in the form of an endless belt. Reference numeral 43 moves downward from above on the side in contact with each image carrier 10.

Here, when a color image is formed by the color image forming apparatus of the second embodiment, the image carrier which is opposed to the toner carrier 21 of the first developing device A1 containing the yellow toner is used. By rotating 10, the surface of the image carrier 10 is uniformly charged by the charging device 41, and the image carrier 10 thus charged is exposed by the exposure device 42 in accordance with the image signal, An electrostatic latent image is formed on the surface of the image carrier 10.

Then, in the developing area where the image carrier 10 on which the electrostatic latent image is formed and the toner carrier 21 of the first developing device A1 face each other, the toner carrier 2
1 and the image carrier 10 are respectively moved upward from below, and the yellow toner is supplied from the toner carrier 21 to the electrostatic latent image portion formed on the image carrier 10, and the image carrier 1
At 0, a yellow toner image corresponding to the electrostatic latent image is formed.

Next, the yellow toner image formed on the image carrier 10 is transferred to the intermediate transfer member 43, and the yellow toner remaining on the image carrier 10 after the transfer is cleaned. The image carrier 10 is removed by the device 44.

Then, in the same manner as in the first developing device A1, the magenta color and the magenta color are sequentially applied to each image carrier 10 facing each toner carrier 21 in the second to fourth developing devices A2 to A4. A cyan and black toner image is formed, and the magenta, cyan, and cyan toner images thus formed on each image carrier 10 are formed.
The black toner image is sequentially transferred to the intermediate transfer body 43 to which the yellow toner image has been transferred as described above, and a full-color toner image is formed on the intermediate transfer body 43.

Thereafter, similarly to the above-mentioned first color image forming apparatus, the recording sheet 46 is transferred from a paper cassette 45 provided at the lower portion of the color image forming apparatus to the intermediate transfer body 43 and the transfer roller 43 by a feed roller 47. The full color toner image formed on the intermediate transfer member 43 is transferred to the recording sheet 46, and the full color toner image thus transferred on the recording sheet 46 is fixed by the fixing device 49. The toner is fixed on the recording sheet 46 and discharged, and the toner remaining on the intermediate transfer member 43 without being transferred is removed from the intermediate transfer member 43 by the cleaning device 50.

[0081]

As described above in detail, in the developing device according to the present invention, the toner carrier is rotated so as to move upward from below in the developing area facing the image carrier.
At a position on the upstream side in the rotation direction of the toner carrier from the regulating member,
In supplying toner from the toner supply member to the toner carrier, a receiving member was provided below the toner supply member, a toner retaining portion for retaining the toner supplied to the toner carrier was provided, and a blade member was provided. When the toner feeding member is rotated in the apparatus main body and the toner accommodated in the apparatus main body is supplied to the toner retaining section by the blade member, the blade member is moved to the toner retaining section at a position where the toner is supplied to the toner retaining section. So that the toner conveyed by the blade member flows into the toner retaining portion along the blade member, and a sufficient amount of toner is supplied to the toner retaining portion and retained. became.

As a result, in the developing device of the present invention, the toner retained in the toner retaining section is supplied to the toner carrier by the toner supply member, and the rotation speed of the toner feeding member is increased. Without this, a sufficient amount of toner can be supplied to the toner carrier by the toner supply member. In particular, even when the amount of toner in the apparatus main body becomes small, a sufficient amount of toner can be supplied by the toner carrier. The toner is stably guided to the development area and used for development, and even when a solid image is formed, the occurrence of density reduction and blurring is suppressed, so that an image having a sufficient image density can be obtained. became.

Further, in the developing device according to the present invention, at the position where the toner is supplied to the toner retaining portion, the inclination angle θ of the blade member inclined downward toward the toner retaining portion is determined by the toner. When the angle of repose is set to be equal to or larger than the angle of repose, the toner on the blade member surely flows into the toner retaining portion, and a sufficient amount of toner is retained in the toner retaining portion, so that an image having a sufficient image density can be obtained. Can now be obtained.

In the developing device according to the present invention, the blade member has a bending elastic modulus X (MPa) of 2000 to 5000 MPa and a thickness d (mm) of 0.05 to 0.5. When the range of 25 mm is satisfied and the condition of 150 ≦ X · d ≦ 1000 is satisfied, when the toner feeding member is rotated and the toner is supplied to the toner retaining portion by the blade member, the weight of the toner And the toner on the blade member is prevented from falling from the blade member before being guided to the toner retaining portion, and a sufficient amount of toner is supplied to the toner retaining portion by the blade member. The blade member was appropriately elastically deformed and softly contacted with the apparatus main body, and the frictional noise during rotation was reduced.

Further, in the developing device according to the present invention, at the position where the toner is supplied to the toner retaining portion, the blade member is moved from the receiving member to the toner retaining portion side by 10 to 20 mm. When the blade member is made to protrude within the range, the blade member does not significantly deform due to the weight of the toner and the like, and even when the blade member is deformed, the tip of the blade member reaches the position of the receiving member. Thus, the toner on the blade member is reliably supplied to the toner retaining section.

Further, in the developing device according to the present invention, the blade member comes into contact with the rotating blade member at a position above a position where the blade member supplies toner to the toner retaining portion, and the blade member contacts the rotating blade member. Is provided, the toner remaining on the blade member without being supplied to the toner retaining portion is scraped off from the blade member by the scraping member and supplied to the toner retaining portion. As a result, more toner is supplied to the toner accumulation section.

In the color image forming apparatus according to the present invention, a plurality of developing devices accommodating toners of different colors and the toner images formed on the image carrier by these developing devices are transferred in an overlapping manner. In the color image forming apparatus provided with the intermediate transfer member, the developing device as described above in the present invention is used, so that the image carrier is moved from the lower side to the upper side in the developing area to obtain a sufficient image density. Image forming apparatus, and the apparatus can be made compact in accordance with the configuration of the color image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a conventional developing device.

FIG. 2 is a schematic explanatory diagram of a developing device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a toner feeding member used in the developing device according to the embodiment, and illustrating a state of a blade member in the toner feeding member at a position where toner is supplied to a toner retaining portion.

FIG. 4 is an explanatory diagram illustrating another example of the toner feeding member used in the developing device according to the embodiment, and illustrating a state of a blade member in the toner feeding member at a position where toner is supplied to a toner retaining portion. .

FIG. 5 is an explanatory diagram illustrating a state in which a scraping member that comes into contact with a rotating blade member is provided at a position above a position where toner is supplied to a toner retaining portion in the developing device according to the eighth embodiment.

FIG. 6 is a schematic explanatory diagram of a color image forming apparatus according to the first embodiment of the present invention.

FIG. 7 is a schematic explanatory view of a color image forming apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Image carrier 20 Apparatus main body of a developing device 21 Toner carrier 22 Toner sending member 22a Blade member 23 Receiving member 24 Toner retaining part 25 Toner supplying member 27 Restriction member 43 Intermediate transfer body A1 to A4 Developing device t Toner θ Toner retaining part The inclination angle at which the blade member is inclined toward the toner retaining portion at the position where the toner is supplied to the toner container l The length of the leading end of the blade member projecting from the receiving member toward the toner retaining portion at the position where the toner is supplied to the toner retaining portion

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/01 113 G03G 15/08 507E (72) Inventor Izumi Izumi 2-3-3 Azuchicho, Chuo-ku, Osaka-shi No. 13 Osaka International Building Minolta Co., Ltd. F term (reference) 2H030 AB02 AD01 AD03 BB02 BB23 BB24 BB42 BB46 2H077 AA37 AB03 AB06 AB14 AB15 AC04 AC16 AD02 AD06 AD13 AD17 BA02 BA03 CA12 CA19 GA13

Claims (6)

[Claims] 1. A toner carrier having a roller shape is rotated so as to move upward from below in a developing area facing an image carrier, and toner is supplied to the toner carrier from a toner supply member. At a position downstream of the supply member in the rotation direction of the toner carrier, the regulating member regulates the amount of toner conveyed by the toner carrier, and guides the toner to the development area by the toner carrier to perform development. A rotatable toner feeding member having a blade member in the apparatus main body, and a receiving member provided below the toner supplying member to provide a toner retaining portion for retaining the toner supplied to the toner carrying member. In rotating the toner feeding member of the above, the toner contained in the apparatus main body is guided to the toner retaining portion by the blade member,
A developing device, wherein a blade member provided on a toner feeding member is inclined downward toward the toner retaining portion at a position where the toner is supplied to the toner retaining portion. 2. The developing device according to claim 1, wherein
The blade member provided on the toner feeding member is configured such that an inclination angle θ inclined downward toward the toner retaining portion at a position where the toner is supplied to the toner retaining portion is equal to or larger than the toner repose angle. Developing device. 3. The developing device according to claim 1, wherein the blade member has a flexural modulus X (MPa) of 20.
00 to 5000 MPa, thickness d (mm) is 0.05
≦ X · d ≦ 100
A developing device satisfying the condition of 0. 4. The developing device according to claim 1, wherein the blade member provided on the toner feeding member is provided at a position where toner is supplied to the toner retaining portion from the receiving member. 10-20mm on the side where toner stays
A developing device that projects in the range of. 5. The developing device according to claim 1, wherein the blade member contacts the rotating blade member at a position higher than a position where the blade member supplies toner to the toner retaining portion. And a scraping member for scraping off the toner on the blade member. 6. A color image comprising a plurality of developing devices accommodating toners of different colors, and an intermediate transfer member onto which a toner image formed on an image carrier by each of these developing devices is transferred in a superimposed manner. 6. A color image forming apparatus, wherein the developing device according to claim 1 is used as the developing device.