JP3384261B2 - Developing roller and image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller capable of preventing color mixture of toner and an image forming apparatus of an orthogonal transfer system using this developing roller as a developing means.

[0002]

2. Description of the Related Art In recent years, as represented by a laser printer, a toner type image forming apparatus capable of forming a clear image with excellent resolution has become widespread. Among such toner type image forming apparatuses, Japanese Patent Application No. 7-328600
As disclosed in, the orthogonal transfer type image forming apparatus that moves the toner image carrier in a direction orthogonal to the conveying direction of the printing paper and transfers the toner image in small steps one by one is small in size due to its structure. It is very suitable to promote

A conventional image forming apparatus compatible with color by such an orthogonal transfer system will be described below.

FIG. 9 is a schematic configuration diagram of a conventional image forming apparatus, FIG. 10 is a perspective view showing a transfer process of the conventional image forming apparatus, and FIG. 11 is a toner layer of a developing roller of the conventional image forming apparatus. It is a schematic diagram showing the formation state of.

9 to 10, a toner image carrier 1 composed of a photosensitive belt whose surface is coated with a layer of an organic photoconductive material comprises a plurality of support rollers 2, displacement rollers 3, transfer counter rollers 4 and the like. Roller is stretched in the direction orthogonal to the conveying direction of the printing paper 5, and the toner image is formed on the surface of the toner image carrier 1 by rotating in the direction of the arrow during image formation. Around the toner image carrier 1, a charging unit 6, a developing unit 7, a cleaning unit 8, a charge eliminating unit 9 and the like are arranged, and the upper portion of the toner image carrier 1 is exposed to irradiate a laser beam. Means 10 are arranged. As shown by the arrow in FIG. 9, the toner image carrier 1
When is rotated in the direction orthogonal to the conveyance direction of the printing paper 5,
The portion passing through the charging means 6 is uniformly charged to about -600V. The exposure means 10 are cyan, magenta, yellow,
The surface of the toner image carrier 1 is irradiated with one line of laser light corresponding to the four primary colors based on the image signals of the four primary colors of black. The potential of the part irradiated with laser light is -1
By increasing the voltage to about 00V, an electrostatic latent image divided into four for each primary color is simultaneously formed on the surface of the toner image carrier 1. When the toners of the four primary colors are pressed against the portion on which the electrostatic latent image is formed by the developing roller 11, the toner image carrier 1
Toner images for each of the four primary colors that have become visible images appear one after another.

As shown in FIGS. 9 to 10, the developing means 7 is composed of four parts for each primary color.
Is cyan, developing means 7M is magenta, developing means 7Y is yellow, and developing means 7B is black, so that cyan, magenta, and
Toner layers of four primary colors of yellow and black are formed separately on the common developing roller 11 into four primary colors. Figure 1
As shown in FIG. 1, the developing roller 11 is formed with four toner layers 12 of cyan, magenta, yellow, and black from the left, and each toner layer 12 is separated by a gap 13 or a gap 14 to prevent color mixture. There is this gap 1
Since the portions 3 and 14 are sealed by the sealing materials 15 and 16, the toner is not normally attached.

The characteristic of such an orthogonal transfer type image forming apparatus is that, as shown in FIG. 10, the rotation of the toner image carrier 1 and the conveyance of the printing paper 5 are temporarily stopped and the stationary printing is performed at the time of transfer. The toner image carrier 1 is transferred onto the sheet 5 by the transfer facing roller 4
Is to be displaced by being rubbed with the movement of. At this time, the displacement roller 3 is displaced in accordance with the movement of the transfer facing roller 4 in order to eliminate the slack of the toner image carrier 1.

Each time the transfer of one step is completed, the transfer counter roller 4 passes over the printing paper 5 and moves out of the area of the printing paper 5, so that the toner image carrier 1 is separated from the printing paper 5. . Then, the transportation of the printing paper 5 is started, but the transportation distance of the printing paper 5 is only the width of the toner layer 12 of each color shown in FIG. Printing paper 5 is toner layer 1
The two widths are intermittently sent to the fixing means 17 side, and the fixing means 17 presses the printing paper 5 on which the image is transferred with the pressure roller 18.
It is sandwiched by the heating roller 19 having a heat source inside, and the toner particles are melted and fixed on the printing paper 5.

[0009]

However, in the conventional image forming apparatus as described above, as shown in FIG.
The outer diameter of the developing roller 11 is the same throughout the entire length. Therefore, even if the gaps 13 are formed by sealing the gaps 13 between the adjacent toner layers 12 of the developing roller 11 with each other, the entire circumference of the developing roller 11 is not sealed. Toner scattered from the gap 1
However, there is a problem that the toner moves to the adjacent toner layer 12 by moving 3 to cause color mixing of the toner.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a developing roller in which color mixing of toner is prevented, and an image forming apparatus in which color mixing of toner is prevented.

[0011]

In order to solve this problem, a developing roller of the present invention is a developing roller for holding toner layers of a plurality of colors at different positions in the axial direction. A step portion that is thinner than the outer diameter of the portion where the toner layer is held is provided so that the toner mixed from the adjacent toner layers cannot cross the step portion.

According to the present invention, it is possible to provide a developing roller in which color mixing of toner is prevented.

Further, the image forming apparatus of the present invention conveys the toner image carried on the toner image carrier, which is stretched by a plurality of rollers in the direction orthogonal to the conveying direction of the printing paper, by the transfer facing roller to convey the printing paper. An image forming apparatus of an orthogonal transfer system for transferring onto a printing paper in a direction orthogonal to the direction and fixing the toner image transferred onto the printing paper, wherein the developing roller of the present invention is used as a developing means for developing a toner image carrier. This is the configuration used.

According to the present invention, it is possible to provide an image forming apparatus in which color mixing of toner is prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a developing roller for holding toner layers of a plurality of colors at different axial positions, wherein the toner layers are held between adjacent toner layers. The toner has a structure in which a step portion thinner than the outer diameter of the portion to be formed is provided, and the toner mixed in from the adjacent toner layers cannot cross the step portion, so that it has an effect of preventing toner color mixing at the stage of the developing roller. .

According to a second aspect of the present invention, a toner image carried on a toner image carrier stretched by a plurality of rollers in a direction orthogonal to the printing paper conveying direction is transferred to a printing paper by a transfer facing roller. An image forming apparatus of an orthogonal transfer system for transferring onto a printing paper in a direction orthogonal to the conveying direction of the paper, and fixing the toner image transferred onto the printing paper, wherein the developing means for developing the toner image carrier comprises: In the configuration using the developing roller described above, the toner mixed in from the adjacent toner layers cannot cross the step portion, so that the color mixture of the toner can be prevented at the stage of the developing roller, and the toner on the toner image carrier can be prevented from developing. At the stage, in the non-developing area of the toner image bearing member, the toner image bearing member and the developing roller hardly contact with each other due to the existence of the stepped portion of the developing roller, so that unnecessary toner adhesion and fogging are prevented. It has the effect of being able to stop.

According to a third aspect of the present invention, in the invention according to the second aspect, the toner image carrier is a photoconductor, and an exposing means for exposing the toner image carrier based on an image signal is provided. The toner mixed in from the adjacent toner layers cannot pass through the step portion, so that the color mixture of the toner can be prevented at the stage of the developing roller, and the toner image carrier can be prevented at the stage of developing the toner image carrier. In the non-developing area, since the toner image carrier and the developing roller hardly contact with each other due to the existence of the stepped portion of the developing roller, it has an effect of preventing unnecessary toner adhesion and fogging.

(Embodiment 1) The outline of one embodiment of the present invention is that in a developing roller in which toner layers of a plurality of colors are formed on the same roller, the toner is provided in a gap portion for separating adjacent toner layers. This means that it is possible to prevent toner color mixing by providing a step portion so that it is thinner than the outer diameter of the portion where the layer is formed and preventing the toner mixed in from the adjacent toner layers from crossing the step portion. The image forming apparatus of the orthogonal transfer system using such a developing roller can prevent color mixture of toner. Hereinafter, details of an embodiment of the present invention, which is an image forming apparatus compatible with color, will be described with reference to FIGS. 1 to 8. The same parts as those in the conventional example are designated by the same reference numerals.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to one embodiment of the present invention, and FIG. 2 is a perspective view showing a transfer process of the image forming apparatus according to one embodiment of the present invention, and FIG.
FIG. 3 is a schematic diagram showing a toner layer forming state of a developing roller of an image forming apparatus according to an embodiment of the present invention. 4 to 7 are schematic diagrams showing a transfer state of the image forming apparatus according to the embodiment of the present invention, and FIG. 8 is a schematic diagram of the fixing unit of the image forming apparatus according to the embodiment of the present invention. is there.

1 and 2, a toner image carrier 1 composed of a photosensitive belt whose surface is coated with a layer of an organic photoconductive material comprises a plurality of support rollers 2, displacement rollers 3, transfer counter rollers 4 and the like. The roller is stretched in the direction orthogonal to the conveying direction of the print paper 5, and when the image is formed, the toner image carrier 1 is rotated in the direction of the arrow to form toner images of four primary colors. Around the toner image carrier 1, a charging unit 6, a developing unit 20, a cleaning unit 8, a charge eliminating unit 9 and the like are arranged.
An exposure means 10 for irradiating a laser beam is arranged on the upper part of the. As shown by the arrow in FIG. 1, when the toner image carrier 1 rotates in the direction orthogonal to the conveyance direction of the printing paper 5, the portion passing through the charging means 6 is uniformly charged to about −600V. The exposing means 10 irradiates the surface of the toner image carrier 1 with laser light corresponding to the four primary colors on the surface of the toner image carrier 1 based on the image signals of the four primary colors of cyan, magenta, yellow and black. By increasing the potential of the portion irradiated with the laser light to about −100 V, an electrostatic latent image divided into four for each primary color is simultaneously formed on the surface of the toner image carrier 10. When the toners of the four primary colors are pressed by the developing roller 21 onto the portion where the electrostatic latent image is formed, the toner images of the four primary colors that have become the visible image appear on the toner image carrier 1 one after another.

As shown in FIG. 3, when the cover is spread,
The four primary color toner layers 12 formed on the common developing roller 21 in four primary colors are simultaneously developed to develop the four primary colors. At the time of development, the developing means 20 causes the developing roller 21 to which the negatively charged toners of the four primary colors are attached in order to make the electrostatic latent images corresponding to the four primary colors visible images. The toner images of the four primary colors are transferred by pressing the four primary color toners onto the surface of the toner image carrier 1 onto the electrostatic latent image portion divided into the four primary colors. It is formed in the state divided into.

As shown in FIGS. 1 and 2, the developing means 20 is composed of four parts for each primary color.
C is cyan, developing means 20M is magenta, developing means 20
Y is yellow, and the developing means 20B is black.
Toner layers of four primary colors of magenta, yellow, and black,
It is formed on the common developing roller 21 by being divided into four for each primary color.

As shown in FIG. 3, toner layers 12 of four colors of cyan, magenta, yellow, and black are formed on the developing roller 21 from the left, and the toner layers 12 are formed between the toner layers 12 to prevent color mixing. A gap 22 or a gap 23 is provided, but since the gap portion is sealed by the sealing materials 24 and 25, the toner is not normally attached. However, even if the gap 22 is formed by sealing the space between the adjacent toner layers 12 of the developing roller 21 with the sealing material 24, it does not seal the entire circumference of the developing roller 21, so that the adjacent toner layers 12 are not separated from each other. The mixed toner may reach the gap 22.

Even in such a case, in the developing roller 21 used in the embodiment of the present invention, the surrounding toner layer 1 is provided.
The gap 22 is made thinner than the outer diameter of the part where 2 is formed.
Since the stepped portion 26 is provided in this portion, the toner mixed in from the adjacent toner layers 12 does not cross over the stepped portion 26 and the toner color mixture does not occur.

At the developing stage, the gaps 22 and 23 provided in the developing roller 21 cause streak-like non-development areas on the toner image carrier 1 where no toner adheres. Become. In the non-developing area generated corresponding to the gap 22 in this, the gap 22 of the developing roller 21
Due to the presence of the stepped portion 26 provided at, the toner image carrier 1 and the developing roller 21 hardly contact with each other. Therefore, in the image forming apparatus according to the embodiment of the present invention, unlike the conventional example, it is possible to prevent toner color mixing at the stage of the developing roller 21, and at the stage of developing, unnecessary toner on the toner image carrier 1 is removed. It is also possible to prevent the adhesion and fog.

As for the relationship between the width of the gap 22 of the developing roller 21 and the width of the step portion 26, the width of the step portion 26 may be expanded to the entire width of the gap 22, but in this case, the gap 2
2 in the non-developing area that occurs corresponding to
Since the toner image carrier 1 and the toner image carrier 1 do not come into contact with each other at all, it is possible to more completely prevent unnecessary toner adhesion and fogging.

The ratio of the width of the toner layer 12 for one color and the width of the gap 22 in the developing roller 21 is {1: 1}, {2 :.
1}, {3: 1}, etc. may be considered, but it is ideal for simplification of the description, but it is assumed that the toner layers of the four primary colors are formed without gaps. Proceed. Incidentally, when the printing paper 5 is transported, the width of the toner layer 12 for one color is required as the transportation distance.

At the time of transfer onto the print sheet 5, as shown in FIG. 2, the transfer of the print sheet 5 is temporarily stopped by interrupting the transfer of the print sheet 5.
The printing paper 5 is kept stationary on 7 (see FIG. 1), and the rotation of the toner image carrier 1 is stopped. Then, the portion of the toner image carrier 1 on which the four primary color toner images are formed is rolled from the back side by the transfer counter roller 4 and rubbed against the printing paper 5 to transfer the toner images of the four primary colors. Is displaced by one step in the opposite direction from the left end or the right end.
At this time, the transfer end surface Z of the toner image carrier 1 that has transferred the toner images of the four primary colors is sequentially separated from the print paper 5 as the transfer counter roller 4 passes. During the transfer process, a positive voltage is applied to the transfer plate 27 on which the printing paper 5 is placed, and the negatively charged toner images of the four primary colors are attracted from the surface of the toner image carrier 1 to be peeled off and transferred to the printing paper 5. . In addition,
The transfer by the toner image carrier 1 is possible not only in the forward path but also in the backward path as described above. At this time, when the moving direction of the toner image carrier 1 is viewed from the print paper 5 side, the toner image carrier 1 is displaced on the print paper 5 in a direction orthogonal to the conveyance direction of the print paper 5.

Each time the transfer for one step is completed, the transfer counter roller 4 passes over the printing paper 5 and moves out of the area of the printing paper 5, so that the toner image carrier 1 is separated from the printing paper 5. . Then, the transportation of the printing paper 5 is started, but the transportation distance of the printing paper 5 is only the width of the toner layer 12 for one color as described above.

The method of forming a color toner image starts from the state shown in FIG. 4, but only the {black} toner image is transferred in one step. Next, as shown in FIG. 5, the toner image of {black, yellow} is transferred in one step, and the toner image of {black, yellow} is overlaid on the first column.
Similarly, as shown in FIG. 6, the toner image of {black, yellow, magenta} is transferred in one step, and the toner image of {black, yellow, magenta} is displayed in the first row and {black, yellow} in the second row. } Toner images are overlaid. After that, as shown in FIG. 7, in one step {black, yellow,
A toner image of magenta, cyan} is transferred, a color toner image is formed by a toner image of {black, yellow, magenta, cyan} in the first column, and a black toner image is formed in the second column.
The yellow and magenta toner images are superposed on the third row, and the black and yellow toner images are superposed. At the end of the transfer, just following the reverse route, the toner image of {black, yellow, magenta, cyan} was transferred in one step, but black was missing, {yellow, magenta, cyan}.
Furthermore, yellow is also missing and becomes {magenta, cyan}, and finally only {cyan}.

As shown in FIG. 1, the cleaning means 5
The residual toner on the surface of the toner image carrier 1 is removed by a cleaning blade or a cleaning brush to collect as waste toner, and the surface of the toner image carrier 1 is physically cleaned. Then, the discharging unit 9 neutralizes the negative charges remaining on the surface of the toner image carrier 1 after removing the residual toner, and electrically cleans the surface of the toner image carrier 1. In addition, the installation of the static elimination means 9 is not an essential requirement.

After repeating the above steps, the printing paper 5 is gradually fed to the fixing means 17 side, as shown in FIG.
The fixing unit 17 sandwiches the printing paper 5 on which the image is transferred between the pressure roller 18 and the heating roller 19 having a heat source inside, and melts the toner particles to fix the printing paper 5. After all the images have been transferred to the printing paper 5,
Since the printing paper 5 is carried out without stopping, the heat source of the heating roller 19 may remain on. However, printing paper 5
If the image is being transferred to the printing paper 5, the printing paper 5 is in a stopped state, so it is necessary to temporarily turn off the heat source of the heating roller 19 or move the heating roller 19 away from the printing paper 5. Further, as shown in FIG. 8, by adopting as the fixing means 28 a heat source 29 and a reflecting plate 30 and installing a reflecting plate 31 below the fixing means 28 to improve the thermal efficiency, There is also a method of fixing the toner without contacting it. As described above, a series of image forming steps is completed.

Finally, to briefly describe the matters relating to claim 2 of the present invention, it is not always necessary to use a photoconductor as the toner image bearing member, and there is a case where an exposing means is not required. This is because a toner image can be formed by forming an electrostatic latent image with a heat source and developing it.
This is because it is possible to form a toner image by engraving a print image by blowing off the toner image carrier, which is solidly coated with toner, with an air jet.

[0034]

As described above, the developing roller of the present invention is a developing roller which holds toner layers of a plurality of colors at different axial positions, and a portion where the toner layers are held between adjacent toner layers. A stepped portion that is thinner than the outer diameter of the toner is provided so that the toner mixed in from the adjacent toner layers cannot cross the stepped portion.

As a result, toner color mixture can be prevented at the stage of the developing roller, and a clear image can be formed.

Further, in the image forming apparatus of the present invention, the toner image carried on the toner image carrier stretched by the plurality of rollers in the direction orthogonal to the conveying direction of the print sheet is conveyed by the transfer opposing roller. An image forming apparatus of an orthogonal transfer system for transferring onto a printing paper in a direction orthogonal to the direction and fixing the toner image transferred onto the printing paper, wherein the developing roller of the present invention is used as a developing means for developing a toner image carrier. This is the configuration used.

As a result, the toner scattered from the adjacent toner layers cannot pass through the step portion, so that the color mixture of the toner can be prevented at the stage of the developing roller, and at the stage of developing on the toner image bearing member. In the non-development area, since the toner image carrier and the developing roller hardly come into contact with each other due to the presence of the stepped portion of the developing roller, it is possible to prevent unnecessary toner adhesion and fogging, so that both sides can form a clear image. An image forming apparatus for forming can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a transfer process of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a schematic diagram showing a toner layer forming state of a developing roller of an image forming apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing a transfer state of the image forming apparatus according to the embodiment of the present invention.

FIG. 5 is a schematic diagram showing a transfer state of the image forming apparatus according to the embodiment of the present invention.

FIG. 6 is a schematic diagram showing a transfer state of the image forming apparatus according to the embodiment of the present invention.

FIG. 7 is a schematic diagram showing a transfer state of the image forming apparatus according to the embodiment of the present invention.

FIG. 8 is a schematic diagram of a fixing unit of the image forming apparatus according to the embodiment of the invention.

FIG. 9 is a schematic configuration diagram of a conventional image forming apparatus.

FIG. 10 is a perspective view showing a transfer process of a conventional image forming apparatus.

FIG. 11 is a schematic view showing a toner layer forming state of a developing roller of a conventional image forming apparatus.

[Explanation of symbols]

1 Toner image carrier 2 Support roller 3 Displacement roller 4 Transfer opposite roller 5 printing paper 6 charging means 7 Developing means 7C developing means 7M developing means 7Y developing means 7B developing means 8 Cleaning means 9 Static elimination means 10 Exposure means 11 Developing roller 12 Toner layer 13 gap 14 Gap 15 Seal material 16 Seal material 17 Fixing means 18 Pressure roller 19 Heating roller 20 developing means 20C developing means 20M developing means 20Y developing means 20B developing means 21 developing roller 22 Gap 23 Gap 24 Seal material 25 Seal material 26 Step 27 Transfer plate 28 fixing means 29 heat source 30 reflector 31 Reflector

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Kizu 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masashi Ogawa, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. In-house (72) Inventor Koji Ueda 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Kazuo Hakukawa 1006, Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Yukinori Hara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-63-89873 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) G03G 15/08 501 G03G 15/08 503 G03G 15/01 113 B41J 2/385

Claims (3)

(57) [Claims] 1. A developing roller for holding toner layers of a plurality of colors at different positions in the axial direction, wherein a step portion thinner than the outer diameter of the portion holding the toner layers is provided between adjacent toner layers. Developing roller. 2. A toner image carried on a toner image carrier stretched by a plurality of rollers in a direction orthogonal to the conveying direction of the printing paper is transferred by a transfer counter roller in a direction orthogonal to the conveying direction of the printing paper. An image forming apparatus of an orthogonal transfer system for transferring a toner image onto a print sheet and fixing the transferred toner image onto a printing paper, wherein the developing roller according to claim 1 is used as a developing unit for developing the toner image carrier. Image forming apparatus. 3. The image forming apparatus according to claim 2, wherein the toner image bearing member is a photoconductor, and an exposing unit for exposing the toner image bearing member based on an image signal is provided.