JP2004271549A - Electrophotographic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic system having high image quality, which does not form an abnormal image such as scattering or a black stripe without causing irregularity in a halftone image (graphic image) even when a carrying guide plate rubs transfer paper by setting mold temperature in molding to be high and the surface roughness of the carrying surface of the carrying guide plate to Ra≤0.8μm. <P>SOLUTION: In the electrophotographic system equipped with a fixing device 10 having the carrying guide plate 17 as a fixing entrance guide plate, the plate 17 is made of heat resistant resin and the surface roughness of the carrying surface 17a of the plate 17 is Ra≤0.8μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic apparatus provided with a fixing device having a conveyance guide plate as a fixing entrance guide plate.
[0002]
[Prior art]
2. Description of the Related Art An electrophotographic apparatus (electrophotographic image forming apparatus) transfers a toner image on a photoreceptor onto transfer paper, and then fixes the toner image by applying heat and pressure by a fixing device. The fixing device includes, for example, a heating roller and a pressure roller, and performs fixing when a transfer sheet is passed through a nip portion between both rollers.
2. Description of the Related Art In an electrophotographic apparatus, a molded product and a manufacturing method for manufacturing a transport guide plate used as an entrance guide plate for guiding transfer paper to a fixing device are known (for example, see Patent Document 1).
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-108166
[Problems to be solved by the invention]
In the molded article and the manufacturing method described in Patent Document 1, the transportability is increased, and the strength and dimensional accuracy are improved by setting the surface roughness of the transport guide plate to 10 μm or less.
However, if Rma × 10 μm, there is no problem in conveyance, but depending on the low-temperature and low-humidity environment and the paper type, halftone images (graphic images) are disturbed due to rubbing between the conveyance guide plate and the recording paper, and dust and black stripes are disturbed. Abnormal image may occur.
FIG. 7 is a diagram for explaining the measurement of the surface roughness of a conventional transport guide plate and the measurement characteristics. Usually, molding is performed at a mold temperature of about 50 ° C. to 80 ° C., and the surface roughness of the molded product is not good. To describe one example of the measurement of the surface roughness, it was measured at a cutoff of 0.8 mm and found to be Ra 1.6 μm, Rz 6.7 μm, and Rma × 11.2 μm.
When this entrance guide plate is used in an actual machine, there is no problem in transportability, but in a low humidity environment such as 10 ° C. and 15% RH, and in some paper types, halftone images and graphic images are disturbed and abnormal images such as dust and black stripes are generated. May occur. This is due to static electricity generated when the guide plate and the transfer paper of the unfixed image are rubbed, and the surface roughness of the guide plate is not good.
FIG. 8 is a schematic perspective view showing a conventional transport guide plate. FIG. 9 is a schematic perspective view of the transport guide plate of FIG. 8 viewed from different angles. FIG. 10 is a schematic end view showing the transport guide plate of FIG. 8 to 10, the surface roughness of the paper passing surface (transport surface) 17 a is not good. When the mold temperature is increased in the shape of the transport guide plate 17 shown in FIGS. 8 to 10, warpage or falling occurs as shown in FIGS.
[0004]
FIG. 11 is a schematic perspective view showing a conventional transport guide plate reinforced with ribs. FIG. 12 is a schematic perspective view of the transport guide plate of FIG. 11 viewed from different angles. FIG. 13 is a schematic end view showing the transport guide plate of FIG.
The transport guide plate 17 shown in FIGS. 11 to 13 is reinforced by ribs 17b to prevent it from falling down or warping. However, as a side effect, sinking may occur on the paper passing surface (transport surface) 17a.
The shape of the fixing entrance guide plate (conveyance guide plate) 17 is such that the conveyance guide plate 17 is formed near the center in order to suppress the waving of the leading edge of the transfer paper when entering the fixing nip and to prevent the transfer paper from entering the fixing nip. Except for the ribs 17b at the front and rear, the shape is planar. If the transfer surface 17a has sink marks or the like, the transferability is not stable, which causes wrinkles.
In electrophotographic equipment, a resin-made transport guide plate that requires heat resistance is used, and since heat resistance is required, the filling amount of glass fibers, glass beads, and the like is large, and ordinary molded products have low surface roughness. Not good. Therefore, an abnormal image such as dust or black streak may occur as described above.
SUMMARY OF THE INVENTION It is an object of the present invention to increase the mold temperature during molding so that the surface roughness of the transfer surface of the transfer guide plate is Ra 0.8 μm or less. It is an object of the present invention to provide a high-quality electrophotographic apparatus which does not generate abnormal images such as dust and black lines without disturbing the image).
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the invention of claim 1, in an electrophotographic apparatus including a fixing device having a conveyance guide plate as a fixing entrance guide plate, the conveyance guide plate is made of a heat-resistant resin, The most important feature is an electrophotographic apparatus in which the surface roughness of the conveying surface of the guide plate is 0.8 μm or less.
According to a second aspect of the present invention, the main feature of the electrophotographic apparatus according to the first aspect is that the transport surface has a substantially planar shape, and the transport surface uses a transport guide plate having no sink.
According to the third aspect of the present invention, a pneumatic pressure is applied to a surface other than the transfer surface during the formation of the transfer guide plate, and a sink is forcibly formed on the surface to use a transfer guide plate having no sink in the transfer surface. The electrophotographic apparatus according to claim 2 is a main feature.
According to a fourth aspect of the present invention, an electrophotographic apparatus using a transport guide plate having all of the first to third aspects is a main feature.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic overall view showing an embodiment of the electrophotographic apparatus of the present invention as a printer. FIG. 2 is an enlarged schematic sectional view showing the fixing device of FIG.
In the printer 1 shown in FIG. 1, recording paper conveyed from a paper feed cassette 8 is conveyed to a latent image carrier composed of a photoreceptor 2 at timing by a registration roller 9. The photoreceptor 2 is driven to rotate clockwise, and the surface thereof is charged by a charging roller 3, and is irradiated with laser light from a laser optical system 4 to form an electrostatic latent image on the photoreceptor 2.
This latent image is visualized by toner when passing through the developing device 5, transferred to the transfer paper conveyed to the photoconductor 2 by the transfer roller 6, and the transfer paper in close contact with the photoconductor 2 is separated by a curvature. .
Thereafter, the transfer paper is transported to the fixing device 10, where the image is fixed, and is discharged to the paper discharge unit 11. On the other hand, the photoreceptor 2 is removed of residual toner by the cleaning device 7 after the charge is removed by the charge removing lamp, and the residual toner is collected.
As shown in FIG. 2, the fixing device 10 presses a transfer sheet 18 of an unfixed image along a fixing inlet guide plate 17 against a fixing roller (heating roller) 12 and a pressure roller 13 to form a transfer sheet therebetween. The nip is transported to the nip and fixed by heat and pressure. After fixing, the sheet is separated by the separation claw 15. In the figure, 19 is a halogen heater, 20 is a thermistor for detecting a fixing roller temperature, 22 is a lever, and 23 is a pressure spring.
[0007]
FIG. 3 is a perspective view showing a transport guide plate of the electrophotographic apparatus according to the present invention. FIG. 4 is a schematic perspective view showing the lower surface of the transport guide plate of FIG. FIG. 5 is a schematic sectional view showing the transport guide plate and the air nozzle of FIG.
The fixing entrance guide plate 17 will be specifically described as an example of the conveyance guide plate of the electrophotographic apparatus according to the present invention. The fixing entrance guide plate 17 is made of a resin that requires heat resistance, and has a large amount of glass fiber, glass beads, or the like.
Examples of the material include PET containing glass (as an example, a filling amount of 30 wt% to 45 wt% of a product such as Rynite glass fiber or glass beads), and PBT containing glass. The heat-resistant temperature is 140 ° C. or higher.
Therefore, in the present invention, the mold temperature at the time of molding is increased, and the surface roughness of the conveying surface of the conveying guide plate is Ra 0.8 μm or less, Rma × 6 μm or less, preferably Ra 0.4 μm or less, Rma × 3 μm or less. And
As specific molding conditions, molding was performed using a glass-containing material PET (trade name: Linite RE9078, filling amount of 40 Wt% of glass, etc.), at a resin temperature of 285 to 295 ° C and a mold temperature of 120 to 125 ° C. .
[0008]
FIG. 6 is a diagram illustrating the measurement results and measurement characteristics of the surface roughness of the transport guide plate. To describe one example of measuring the surface roughness of the conveyance guide plate, it was measured at a cut-off of 0.8 mm, and was Ra 0.2 μm, Rz 0.9 μm, and Rma × 1.6 μm.
The use of the conveyance guide plate having the improved surface roughness prevented the occurrence of the abnormal image which has conventionally occurred. In this way, it is possible to provide a high-quality electrophotographic apparatus that does not disturb a halftone image (graphic image) or the like and does not generate an abnormal image such as dust or black stripes.
Therefore, according to the present invention, since the transport guide plate has no sink mark on the transport surface, the transportability can be stabilized, and a high-quality electrophotographic apparatus without wrinkles or the like can be provided.
As a means for suppressing sink of the transfer guide plate, there is a method of extremely increasing the holding time of the mold at the time of molding. However, the molding cycle is abnormally long, mass production is difficult, and the cost is high, which is not practical.
There is a means to inject gas into the thick part that causes sink marks, but it cannot be inserted at the base of all ribs. There is.
Therefore, in the present invention, air pressure is applied to a surface other than the conveying surface during molding, and a sink is forcibly formed on the surface, so that the sink on the conveying surface can be easily eliminated. That is, as shown in FIG. 4 showing the position of the air nozzle, and FIG. 5 enlarging a main part of the air nozzle and the like, after injecting the resin into the mold, the air pressure of 3 Pa to 10 Pa, and the length of the conveyance guide plate of 300 mm The size of the tip of the air nozzle 21 was 3 to 15 mm ² , and the number of nozzles was 5 to 10.
According to this method, the same effect can be obtained even with a resin having heat resistance, the molding cycle can be the same as the conventional one, a transfer guide plate without sinking can be provided, and an inexpensive electrophotographic apparatus can be provided without increasing costs. .
An abnormal image can be eliminated by combining the above techniques and increasing the mold temperature so that the surface roughness of the transfer surface is Ra 0.8 μm or less. In addition, when the mold temperature is increased, the warpage of the transport guide plate becomes large, so that a reinforcing rib is inserted to prevent the warpage.
Apply air pressure during molding to create sinks on the transfer surface, which are likely to be caused by ribs and thick walls, and create sink marks in places other than the sheet passing surface, so that the sink on the sheet passing surface can be eliminated without lengthening the molding cycle. An electrophotographic apparatus with high image quality and high quality can be provided.
[0009]
【The invention's effect】
As described above, according to the first aspect, the mold temperature during molding is increased, and the surface roughness of the conveying surface of the guide plate is set to Ra 0.8 μm or less. However, it is possible to provide a high-quality electrophotographic apparatus that does not disturb a halftone image (graphic image) or the like and does not generate an abnormal image such as dust and black stripes.
According to the second aspect of the present invention, the transfer guide plate made of resin is used, and the transfer surface of the transfer guide plate has a substantially planar shape. It is possible to provide a high quality electrophotographic apparatus which is stable and free from wrinkles and the like.
According to the third aspect, during molding, air pressure is applied to a surface other than the conveying surface to eliminate sinking of the conveying surface, and the molding cycle is not changed from the conventional one, so that an inexpensive electrophotographic apparatus can be provided.
According to the fourth aspect, since the surface roughness of the transfer surface is set to Ra 0.8 μm or less, an abnormal image can be eliminated. Also, when the mold temperature is increased, the warpage of the transfer guide plate increases, so that reinforcing ribs are inserted. Since the pressure is applied with air pressure during molding, it is possible to provide a low-cost, high-quality, high-quality electrophotographic apparatus without changing the molding cycle, suppressing the sink on the transfer surface, which is likely to be caused by ribs and thick walls. .
[Brief description of the drawings]
FIG. 1 is a schematic overall view showing an embodiment of an electrophotographic apparatus of the present invention as a printer.
FIG. 2 is an enlarged schematic cross-sectional view illustrating the fixing device of FIG. 1;
FIG. 3 is a perspective view showing a transport guide plate of the electrophotographic apparatus according to the present invention.
FIG. 4 is a schematic perspective view showing a lower surface of the transport guide plate of FIG. 3;
FIG. 5 is a schematic sectional view showing a conveyance guide plate and an air nozzle of FIG. 3;
FIG. 6 is a diagram illustrating measurement of surface roughness of a transport guide plate and measurement characteristics.
FIG. 7 is a diagram illustrating measurement of surface roughness and measurement characteristics of a conventional transport guide plate.
FIG. 8 is a schematic perspective view showing a conventional transport guide plate.
9 is a schematic perspective view of the conveyance guide plate of FIG. 8 as viewed from a different angle.
FIG. 10 is a schematic end view showing the conveyance guide plate of FIG. 8;
FIG. 11 is a schematic perspective view showing a conventional transport guide plate reinforced with ribs.
12 is a schematic perspective view of the conveyance guide plate of FIG. 11 viewed from different angles.
FIG. 13 is a schematic end view showing the conveyance guide plate of FIG. 11;
[Explanation of symbols]
1 Printer (electrophotographic device)
17 Transport guide (fixing entrance guide plate)
17a Paper passing surface (transport surface)
17b rib

Claims (4)

In an electrophotographic apparatus provided with a fixing device having a conveyance guide plate as a fixing entrance guide plate, the conveyance guide plate is made of heat-resistant resin, and the surface roughness of the conveyance surface of the conveyance guide plate is Ra 0.8 μm or less. An electrophotographic apparatus, comprising: 2. The electrophotographic apparatus according to claim 1, wherein the transport surface has a substantially planar shape, and a transport guide plate having no sink in the transport surface is used. During the molding of the transport guide plate, air pressure is applied to a surface other than the transport surface, and the transport guide plate in which the sink of the transport surface is eliminated by forcibly forming a sink on the surface is used. The electrophotographic apparatus according to claim 2. An electrophotographic apparatus using a transport guide plate provided with all of claims 1 to 3.

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