JPH02284176A - Image forming device - Google Patents

Abstract

PURPOSE:To form a high quality image without generating any pulling or slack in a transfer material by absorbing the difference in diameter of fixing rollers by setting destaticizing quantity against a leading tip area of the transfer material to be greater than the destaticizing quantity against the parts other than this leading tip area. CONSTITUTION:When the transfer material 8 which is carried by the carrying means 1 is brought close to the fixing rollers 6a and 6b, made of silicone rubber with its surface finished to a mirror surface condition and processed to absorb oil, destaticizing is carried out against the leading tip area of the transfer mate rial 8 by the destaticizing means 5, and the destaticized transfer material 8 is separated from the carrying means 1, fed to the fixing rollers 6a and 6b, and the fixing of the toner image is carried out. The destaticizing quantity of the destaticizing means 5 is set to be smaller at parts other than the leading tip area than at the leadng tip area. Thus, after the leading tip area is fed into the fixing means 11, the transfer material 8 is carried adhered to the carry ing means 1, no pulling or slack is generated in the transfer material 8, and image formation of high quality can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus, and particularly to an image forming apparatus such as a copying machine, a facsimile machine, and a printer that forms an image on a transfer material to obtain a hard copy.

[Conventional technology]

In an image forming apparatus that forms an image on a transfer material and obtains a hard copy based on this image, a conveyance path performs a series of processes from paper feeding, transfer, and fixing to ejecting the transfer material with the image formed outside the apparatus. It is equipped with

In such an image forming apparatus, errors in the mounting positions of component parts or differences in conveyance speed in transfer materials conveyed along the conveyance path cause misalignment during image formation. These main factors include (11) deviations in the mounting positions of each photoreceptor and deviations in circumferential speed from the set reference value, (2) deviations in the exposure position relative to the photoreceptors, and (3) linear velocity of the conveyor belt. There is slippage or sagging of the transfer material caused by discrepancy in the circumferential speed of the fixing roller.

When forming a monochromatic image, the colors are not superimposed, so any deviation during image formation only appears as expansion or contraction of the image, but when forming a color image,
If the image forming position of each color shifts even slightly, color shift will occur.
The occurrence of misalignment during image formation is unacceptable because the image quality will drop sharply.

Japanese Unexamined Patent Publication No. 63-73278 discloses that prior to image formation, test patterns of each color are formed on a transfer belt, the mutual positions of these test patterns are detected by a detection means, and the position of each color is adjusted according to the amount of deviation. A digital color image forming apparatus that changes the writing start timing has been proposed.

However, even if the writing start timing of each color is changed using the method proposed above and the writing is started at the timing when each color completely overlaps, if the transfer body is not conveyed in line with the conveyor belt, misalignment occurs during image formation. Occur.

This discrepancy in the conveyance between the conveyor belt and the transfer body is caused by the fact that when the leading edge of the transfer material is on the fixing roller, if the circumferential speed of the fixing roller is greater than the linear velocity of the conveyor belt, the transfer material is pulled by the fixing roller. Furthermore, if the circumferential speed of the fixing roller is lower than the linear speed of the conveyor belt, this occurs due to the formation of slack in the transfer material.

In Japanese Utility Model Application Publication No. 58-157354, in this case, by providing a valley-shaped guide means for guiding the transfer material to the fixing roller, the difference between the circumferential speed of the fixing roller and the linear speed of the conveyor belt is absorbed. A conveyance guide device has been proposed.

FIG. 7 is an explanatory diagram of the transfer state of the transfer material in the above case, in which the transfer material 8 is initially guided by the valley-shaped guide means;
The toner is transferred between the photoreceptor 2 and the fixing rollers 6a and 6b in an arcuate manner with a total length of 11. At this time, the circumferential speed of the fixing rollers 6a and 6b is generally higher than the linear speed of the conveyor belt, so the transfer material 8 gradually moves upward and finally reaches a total length of 12
It is transported in a straight line (11>12).

Furthermore, in JP-A-62-161157, when the leading edge of the transfer material reaches the fixing roller, the circumferential speed of the fixing roller is set to a first circumferential speed that is lower than the linear velocity of the conveyor belt, and after a predetermined time, the first circumferential speed is set to An image forming apparatus has been proposed that switches to a second peripheral speed that is higher than the peripheral speed to form a loop in the transfer material to prevent slipping.

[Problem to be solved by the invention]

The method proposed in the above-mentioned Japanese Utility Model Publication No. 58-157354 has the drawback that the desired effect cannot be obtained unless the valley-shaped guide means is sufficiently long, resulting in an increase in the size of the device. Furthermore, the method proposed in the above-mentioned Japanese Patent Application Laid-Open No. 62-161157 has a problem in that the device becomes complicated.

On the other hand, in this type of image forming apparatus, sufficient consideration must be given to the fixing roller itself in order to obtain a glossy color image without transfer misregistration. That is, the material of the fixing roller is a condensation reaction room-temperature curing silicone rubber that has good releasability (easiness of toner adhering to the surface of the fixing roller to be peeled off) and does not cause the offset phenomenon in which toner adheres to the surface of the fixing roller. It is necessary to use load-response low-temperature vulcanization type silicone rubber (hereinafter referred to as LTV silicone rubber), give the surface a mirror finish, and impregnate the surface with silicone oil.

The fixing roller obtained in this manner has a problem in that the variation in diameter thereof is relatively large.

When the diameter of the fixing roller changes, the circumferential speed of the fixing roller, whose rotational speed is set to a specified value in advance, changes, causing tension or sagging in the transfer material as described above, which causes misalignment in image formation. becomes.

If the fixing roller is not required to have a mirror finish, the surface can be impregnated with silicone oil and then ground to a specified outer diameter, as shown in Japanese Patent Laid-Open No. 58-36337. If finishing is required, no grinding corrections can be made.

An object of the present invention is to absorb variations in the diameter of the fixing roller in an image forming apparatus equipped with a fixing roller made of silicone rubber whose surface is mirror-finished and treated with oil.
An object of the present invention is to provide an image forming apparatus that forms high-quality images without causing tension or sag in a transfer material.

[Means to solve the problem]

The above purpose is to separate and feed the transfer material to the fixing means, which is equipped with a fixing roller made of silicone rubber whose surface is mirror-finished and treated with oil. This is achieved by setting the amount of charge removal for the region larger than the amount of charge removal for the portion other than the tip region.

[Effect]

When the transfer material conveyed by the conveyance means approaches a fixing roller made of silicone rubber whose surface is mirror-finished and oil-impregnated, the discharging means performs static electricity removal on the tip region of the transfer material, and the static electricity is removed. The transfer material is separated from the conveyance means and sent to a fixing roller, where the toner image is fixed.

The amount of static electricity removed by this static eliminating means is set to be smaller than that of the leading edge area for parts other than the leading edge area, so after the leading edge area is sent to the fixing means, the transfer material is in close contact with the conveying means. The transfer material is conveyed without any tension or sag, and high-quality images are formed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 5 is an explanatory diagram showing the basic configuration of an image forming apparatus to which the present invention is applied, in which 1 is a transport means (transport means) Lt
2a, 2b, 2c are photoreceptors; 3a;

3b and 3c are transfer chargers, 4 is a transfer section, 5 is a static elimination charger, 6a and 6b are fixing rollers, 7 is a conveyance guide,
8 is a transfer material, 9 is a paper feed tray, 10 is a paper discharge plate, 1
1 is a fixing section, 12 is a driving roller, and 13 is a driven roller.

As shown in FIG. 5, a paper discharge plate 1° is disposed on the exit side of a fixing section 11 that includes fixing rollers 6a and 6b, and a conveyance guide 7 is disposed on the entrance side of the fixing section 11. A drive roller 12 and a driven roller 1 are placed between the paper feed tray and the paper feed tray.
A conveyor belt 1 which is attached to 3 is disposed.

A photoconductor 2a and a transfer charger 3a, C
Photoreceptor 2b and transfer charger 3b for (cyan)
, Y (yellow) and a transfer charger 3c are arranged, and a static elimination charger 5 is arranged near the end of the conveyance belt 1 on the conveyance guide 7 side.

The transfer material 8 supplied from the paper feed tray 9 is transferred to the conveyor belt]
The toner image of each color is transferred to the transfer material 8 in the transfer section 4.
The toner images are superimposed and transferred, and the superimposed and transferred toner images are fixed in a fixing section 11.

FIG. 6 is an enlarged view of the boundary between the transfer section and the fixing section in FIG.
8 is a transfer material, 12 is a drive roller, and 14a, 14b are drawer rollers.

As shown in FIG. 6, the transfer material 8 conveyed on the conveyor belt 1 is neutralized by a static elimination charger 5 provided near the drive roller 12, and the neutralized transfer material 8 is guided to the upper guide. The sheet is fed to fixing rollers 5a and 5b via a conveyance guide 7 consisting of a lower guide 7a and a lower guide 7b, where it is fixed, and is pulled out by pull-out rollers 14a and 14b and guided to a paper discharge plate 10. .

FIG. 1 is a block diagram showing the configuration of main parts of an embodiment of the present invention, in which 5 is a static elimination charger, 20 is a high-voltage power supply, and 21 is a control section.

As shown in FIG. 1, in this embodiment, a control section 21 is connected to the high voltage power supply 20 of the static elimination charger 5 shown in FIGS. 5 and 6. The control unit 21 is provided with a select terminal SEL and a trigger terminal TRIG, and by changing the combination of the logical values of the signals of the select terminal SEL and the trigger terminal TRIG, high voltage,
Either a relatively low voltage or zero voltage is selected and output.

FIG. 4 is a sectional view showing the structure of the fixing roller of this embodiment.
In the figure, 22 is a heater, 23 is a 1M core metal, 24 is an LTV silicone rubber cylinder, and 25 is an RTV silicone rubber.

This fixing roller is manufactured as follows.

First, an adhesive is applied to the cylindrical core metal 23 made of aluminum with an outer diameter of 43.4 nm and has a heater 22 inside, and an LTV with a fin thickness of 0.7 is applied.
The silicone rubber cylindrical part 24 is fixed with adhesive and has a thickness of 0.6
Polish until it becomes a crane. LTV formed in this way
KE-130ORTV on the surface of the silicone rubber cylindrical part 24
(manufactured by Shin-Etsu Chemical) diluted with toluene and ethyl acetate
Spray coat TV silicone rubber 25 to a thickness of 80μ.

Next, after drying the obtained fixing roller at 150° C. for 4 hours, silicone oil K F-96 (100C8) was applied.
The final product is completed by soaking it in water for 24 hours at a temperature of 190°C for oil impregnation.

As already mentioned, it has been confirmed that the diameter of the fixing roller thus obtained varies slightly depending on the temperature, viscosity, impregnation time, etc. of the impregnating agent, and the diameter varies within a range of 45±0.2. It is also known that the outer diameter of the obtained fixing roller can be increased economically if it is not saturated and swollen by the impregnation treatment.

Next, the operation of the above embodiment will be explained.

FIG. 2 is an explanatory diagram showing the relationship between the control of the control unit and the output voltage of the high-voltage power supply in this embodiment, and FIGS. FIG. 3 is a signal waveform diagram showing the relationship between the voltage and the static elimination voltage.

3(a) and 3(b) are waveform diagrams showing the position (presence or absence) of the transfer material and the neutralization voltage of the static elimination charger in this example, and FIG. 3(C) (
d) is a waveform diagram showing the position (presence or absence) of the transfer material and the static elimination voltage of the static elimination charger, which was performed for comparison.

As shown in FIG. 5, the transfer material 8 fed from the paper feed tray 9 onto the conveyor belt 1 is conveyed by the conveyor belt 1, and the M (magenta) toner is formed on the photoreceptor 2a by the transfer charger 3a. The image is transferred. Then,
The transfer charger 3
C (cyan) toner images formed on the photoreceptor 2b are superimposed and transferred by the photoreceptor 2b.

In this way, the toner image on the transfer material 8, in which the M (magenta) toner image and the C (cyan) toner image are superimposed and transferred, is conveyed to the photoreceptor 2C position and transferred to the transfer charger 3.
C, a Y (yellow) toner image formed on the photoreceptor 2C is transferred to form a color image.

When the transfer material 8 on which the color image has been formed reaches a distance of 10 mm from directly below the static elimination charger 5 as shown in FIG.
The output signal of RIG is set to "L", the output signal of select terminal SEL is set to "H", and a high voltage is applied from the high voltage power supply 20 to the static elimination charger 5. The state of this high voltage application is shown in FIG. 3 from the tip of the transfer material 8 as shown in
The area up to 0 m continues until it reaches directly below the static elimination charger 5.

During this period, the amount of static electricity removed from the transfer material 8 by the transfer charger 5 becomes large, and the leading edge of the transfer material 8 separates from the conveyor belt 1 and smoothly moves on the lower guide 7b by the fixing roller, as shown by the solid line in FIG. Fixing is performed by moving in directions 6a and 6b, being sandwiched between fixing rollers 5a and 6b, and being pressurized and heated.

When the tip region from the tip of the transfer material 8 to 3On+ passes directly under the static elimination charger 5, the output signals of the trigger terminal TRIG and the select terminal SEL are both set to "L" as shown in FIG. A low voltage is applied to the static elimination charger 5. This low voltage application state is the third
As shown in FIG.
During this period, the amount of static electricity removed from the transfer material 8 by the transfer charger 5 is small, so the transfer material 8 is smoothly conveyed in close contact with the conveyor belt 1. When the transfer material 8 passes directly under the static elimination charger 5 and no longer exists, the third
As shown in Figure (b), the supply of voltage from the high voltage power supply 20 to the static elimination charger 5 is cut off.

As shown in FIG. 3(e) (dl), the static elimination charger 5 performs the same static elimination operation from the time the transfer material 8 reaches directly below the static elimination charger 5 until the transfer material 8 passes directly under the static elimination charger 5. If this is done, the transfer material 8 separated from the conveyor belt 1 may sag, as shown by the dotted line in FIG. , the transfer material 8 is pulled and transfer misalignment occurs.

Moreover, if the static elimination charger 5 is activated only at the leading end of the transfer material 8 and then stopped,
When the humidity is low, abnormal discharge occurs and a discharge bump is formed, deteriorating the image quality.At the same time, toner adheres to the charge wire of the static eliminating charger 5, and the function of the static eliminating charger 5 also deteriorates. If image formation is performed without operating the static elimination charger 5, for example, under low temperature and low humidity conditions of 10° C. and 15% RH,
It becomes difficult to separate the transfer material 8 from the conveyor belt 1.

3(C) (d) shows a comparison example in which the static eliminating charger 5 performs the static eliminating operation on the transfer material 8, and a comparison example in which the static eliminating operation of the present example is performed on the transfer material 8. When the presence or absence of tension or sag was confirmed with respect to the diameter of the fixing roller, the results shown in Table 1 were obtained.

Table 1 Note that in Table 1, × indicates a case where tension or sag occurred in the transfer material 8, and ◯ indicates a case where neither tension or sag occurred in the transfer material 8. As is clear from Table 1, in the comparative example, high quality images can only be formed when the diameter of the fixing roller is within the range of 45±0.05 fins, but in the example, it is 45±0.2 fins.
It is possible to form high-quality images without color shift by absorbing variations in the diameter of the fixing roller within the range fl.

In this way, according to the embodiment, the fixing rollers 6a, 6 are made of oil-impregnated silicone rubber and have mirror-finished surfaces.
b is used, a glossy color image can be obtained, and by setting the amount of charge removed by the charger 5 to be larger in the leading edge area of the transfer material than in other areas, the diameter of the fixing rollers 5a and 5b can be reduced. It is possible to absorb the variations in color images and form high-quality color images without transfer misalignment.

In addition, in the above embodiment, on the LTV silicone rubber cylindrical part,
Although a case has been described in which the fixing roller is spray-coated with RTV silicone rubber, the present invention is not limited to this embodiment, and the present invention is not limited to this embodiment. You can also do that.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to absorb variations in the diameter of the fixing roller of oil-impregnated silicone rubber and form glossy, high-quality images without causing transfer misalignment. I can do it.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the main part of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the relationship between control of the control unit and the output voltage of the high voltage power supply in the embodiment of the present invention, and FIG. 3 is a signal waveform diagram showing the relationship between the position of the transfer material and the static elimination voltage of the static elimination charger in the embodiment of the present invention, FIG. 4 is a sectional view showing the structure of the fixing roller in the embodiment of the present invention, and FIG. Explanatory diagram showing the basic configuration of an image forming apparatus to which the invention is applied, No. 6
The figure is a partially enlarged view of FIG. 5, and FIG. 7 is an explanatory diagram of a conventionally proposed conveyance guide device. 1... Conveyor belt, 2a, 2b, 2C...
... Photoreceptor, 3a, 3b, 3c ... Transfer charger, 5 ... Static elimination charger, 6a, 6b
...Fixing roller, 7...Conveyance guide,
8...Transfer material, 9...Paper feed tray, 1
0... Paper discharge plate, 11... Fixing section, 12... Drive roller, 13... Driven roller, 20... High voltage power supply , 21...
Control part, 23... Al core metal, 24...
LTV silicone rubber cylindrical part, 25...RTV silicone rubber. 1st Lz Fig. 2 (d) H + 4th - Fig. 4

Claims (1)

[Claims] a conveyance means for conveying the transfer material on which the toner image is formed;
A fixing roller provided at the downstream end of the conveyance means and having a mirror-finished surface and oil-impregnated silicone rubber fixing roller fixes the toner image onto the transfer material; In an image forming apparatus, the image forming apparatus includes a static eliminator provided at a side end portion of the transfer material to remove static electricity from the transfer material in order to separate the transfer material from the conveying means and feed the transfer material to the fixing means. An image forming apparatus characterized in that the amount of charge removed for a tip region is set to be larger than the amount of charge removed for a portion other than the tip region.