JP2004045579A - Electrophotographic equipment - Google Patents

Abstract

Provided is an electrophotographic apparatus capable of preventing a decrease in print image quality due to contamination of a fixing device even without a fixing device cleaning mechanism.
A full-color electrophotographic apparatus according to the present invention has means for detecting a paper jam generated in a fixing device, and when a paper jam occurs in a fixing device, a user removes the paper jam sheet and then performs a user operation. In addition to the print data described above, one or more sheets are automatically passed through a fixing device as cleaning sheets to remove toner adhered to a heat roller caused by the paper jam.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic apparatus, and more particularly to an electrophotographic apparatus having a high image quality provided with a unit for cleaning toner stains on a fixing device.
[0002]
[Prior art]
In a conventional full-color electrophotographic apparatus, after a toner image is transferred to paper as a print medium, the paper on which the toner image has been transferred is conveyed and passes between a heat roller and a backup roller of a fixing device, and the toner image is transferred. It is melted and fixed on paper. FIG. 2 shows a main cross section of the fixing device 14 of the conventional full-color electrophotographic apparatus. The fixing device 14 includes a heat roller 19a, a backup roller 20 that presses against the heat roller 19a, a cleaning mechanism 22 that presses against the heat roller 19a, and an oil bottle 21 that supplies oil to the heat roller 19a. The oil supplied from the oil bottle 21 is supplied to the surface of the heat roller 19a, and the sheet on which the toner image (not shown) is transferred is conveyed to the fixing device 14 and is moved between the heat roller 19a and the backup roller 20. When passing through the toner, the toner is melted and fixed on the paper. At this time, the toner remaining on the heat roller 19a without being fixed to the sheet is removed by the cleaning mechanism 22, and the fixing device 14 is cleaned.
[0003]
Japanese Patent Application Laid-Open No. 2002-72748 discloses a single-color printer that shifts to a cleaning mode when the amount of toner in a developing device decreases and sends cleaning paper to a fixing device.
[0004]
[Problems to be solved by the invention]
The conventional full-color electrophotographic apparatus shown in FIG. 2 has a problem that when a paper jam occurs, the toner cannot be completely removed and the life of the fixing device is shortened due to paper stains and heat roller scratches. Further, in the conventional full-color electrophotographic apparatus, since the oil content of the toner is low, oil is supplied from time to time to the surface of the heat roller to peel off the paper, and the paper on which the toner image is placed is heated by the heat roller. When the toner passes, not all of the toner is fixed on the paper, and a small amount of toner remains on the surface of the heat roller. For this reason, the residual toner is fixed on the next sheet to be conveyed, and the printed image is stained. Therefore, in the related art, it is necessary to arrange a cleaning mechanism that contacts the heat roller and always remove the residual toner. In addition, the cleaning capability of the cleaning mechanism itself gradually decreases with an increase in the number of printed sheets, so that there is the trouble of periodically replacing the cleaning mechanism.
[0005]
The problem is that oil-less toners developed in recent years have a high oil content, which increases the releasability of paper, and does not require oil for separation. However, since the residual toner is not completely eliminated, the residual toner accumulates on the heat roller of the fixing device as the number of printed sheets increases, and stains are generated on the printed image.
[0006]
Further, toner contamination of the heat roller of the fixing device is remarkable when paper jam occurs in the fixing device. Although the frequency of paper jams is low, it cannot be eliminated because the paper is used under various conditions depending on the user, such as how to insert the paper into the electrophotographic apparatus and the use environment. When a paper jam occurs, a large amount of residual toner adheres to the heat roller of the fixing device. Therefore, if there is no cleaning means, the entire fixing device must be replaced.
[0007]
The conventional technique described in JP-A-2002-72748 has a problem that the remaining amount of toner in the developing device does not always correspond to the toner stain on the heat roll of the fixing device.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic apparatus capable of solving the above-described problem and preventing a decrease in print image quality due to contamination of the fixing device without providing a fixing device cleaning mechanism.
[0009]
[Means for Solving the Problems]
The full-color electrophotographic apparatus of the present invention has means for detecting a paper jam generated in the fixing device, and when a paper jam occurs in the fixing device, after the user removes the jammed paper, the user's print data and Separately, at least one sheet of paper is automatically passed as a cleaning sheet to the fixing device to remove toner adhered to the heat roller caused by the paper jam.
[0010]
The full-color electrophotographic apparatus of the present invention has a dirt detecting means for detecting toner adhering to the heat roller surface of the fixing device, and when the dirt detecting means detects that the heat roller surface is contaminated by toner adhesion. In addition, one or more sheets of cleaning paper are automatically passed through the fixing device separately from the print data of the user, and the toner adhered to the heat roller is transferred to the cleaning paper.
[0011]
The full-color electrophotographic apparatus of the present invention automatically passes one or more sheets of cleaning paper to a fixing device separately from print data of a user or a user for each preset number of prints, and the toner adhered to a heat roller. To the cleaning paper.
[0012]
The full-color electrophotographic apparatus of the present invention has an input means for passing a cleaning sheet, and the user automatically passes one or more sheets of cleaning paper separately from the print data to the fixing device by the input means. Then, the toner attached to the heat roller is transferred to the cleaning paper.
[0013]
As described above, the surface of the heat roller can be always cleaned by the full-color electrophotographic apparatus of the present invention. As a result, even if a fixing device cleaning mechanism is not provided as in the related art, it is possible to prevent a decrease in image quality due to toner contamination of the fixing device, and to provide a long-life, maintenance-free electrophotographic apparatus.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a main section of an electrophotographic apparatus which is a full-color printer of the present embodiment. The electrophotographic apparatus main body 16 includes developing units 1 to 4 containing toners of four colors of black, yellow, magenta, and cyan, an optical unit 5, a charging unit 8, a photosensitive belt 9, and an intermediate transfer body. A transfer drum 10, a registration roller 11, a transfer roller 12, a static eliminator 13, a fixing device 14, a paper discharge roller 15, and a paper cassette 6 are provided.
[0015]
The operation of the electrophotographic apparatus main body 16 will be described. The charger 8 uniformly charges the photosensitive belt 9 in response to a print start signal from a host not shown in FIG. The optical unit 5 draws a latent image on the photosensitive belt 9 based on print data sent from the host. The drawn latent image is developed by any one of the developing units 1 to 4, and the toner in the developing unit is applied on the photosensitive belt 9. The photosensitive belt 9 is rotated by a driving source (not shown) to transfer the toner image on the photosensitive belt 9 onto the transfer drum 10. In the case of full-color printing, this process is repeated four times while switching the developing units for the four colors. A visible image is formed on the transfer drum 10 by a plurality of color toners, and the paper 7 is pulled out from the paper supply cassette 6 by the paper supply roller 17 when the transfer of the desired full-color toner image is completed or in advance. And waits at the registration roller 11. At a timing when the position of the visible image formed on the transfer drum 10 coincides with the transfer position on the sheet, the sheet waiting at the registration roller 11 starts to be conveyed again and the transfer roller 12 At this point, the visible image is transferred to the paper side. The paper is peeled off from the transfer drum 10 by the neutralizer 13, the toner is fixed on the paper by the fixing device 14, and the paper is discharged to the paper discharge tray 18.
[0016]
Next, the fixing process will be described in detail. FIG. 3 shows a main section of the fixing device 23 according to the present invention. The fixing device 23 includes a heat roller 19b and a pressure belt 24 that is in pressure contact with the heat roller 19b. In addition, a paper jam detection sensor 25 which is a means for detecting a paper jam near the exit of the paper, and a dirt detection sensor 26 which is a means for detecting dirt on the heat roller 19b are arranged near the heat roller 19b. In this embodiment, both the paper jam detection sensor 25 and the dirt detection sensor 26 are used, but either one of the detection means may be used. Here, as the paper jam detection sensor 26, a semiconductor optical sensor that converts the surface reflectance of the heat roller 19b into an electric signal can be used. Although one dirt detection sensor 26 may be provided, a plurality of dirt detection sensors 26 may be disposed along a direction parallel to the rotation axis of the heat roller 19b. Preferably, two dirt detection sensors 26 may be arranged at the center of the right half and the center of the left half of the heat roller 19b. More preferably, three dirt detection sensors 26 may be arranged at both ends and the center of the heat roller 19b.
[0017]
The process of cleaning the fixing device when a paper jam occurs will be described with reference to FIGS. 3 and 4. FIG. When a paper jam occurs, the paper jam detection sensor 25 detects the jam and transmits a detection signal to the host or the printer controller. In response to this signal, the host or the printer controller stops printing and displays a message indicating that printing is stopped due to a paper jam on a display device of the printer main body or a display screen of the host. Next, when the user removes the jammed paper, the paper jam detection sensor 25 detects the presence or absence of the jammed paper, and if there is no paper, the user prints according to a signal from the host not shown here. Separately from the data, the sheet is automatically conveyed from the inside of the apparatus, and the cleaning sheet 27 is passed to the fixing unit 23.
[0018]
The cleaning paper 27 comes into contact with the heat roller 19b, transfers the residual toner 28 attached to the heat roller 19b, and is discharged from the fixing device 23. At this time, the temperature of the heat roller 19b of the fixing device is higher by 5 ° C. to 20 ° C., preferably 5 ° C. to 10 ° C. than in the normal printing mode. This is because the residual toner 28 adhering to the heat roller 19b is more easily transferred to the cleaning paper 27 as it is sufficiently melted. However, if the temperature is too high, the temperature rise of the electrophotographic apparatus itself becomes large, which is not preferable. .
[0019]
Note that there are the following three methods as other means for efficiently transferring to paper without increasing the temperature, and any of these methods may be used. One is a method in which the rotation speed of the fixing device 23 is made slower than in the normal print mode. The residual toner 28 adhering to the heat roller 19b has a longer contact time with the cleaning paper 27 as the transport speed of the cleaning paper 27 is slower, and is easily transferred to the cleaning paper 27. 27 takes too much time to be discharged, resulting in a burden on the user. Therefore, when the rotation speed of the fixing device 23 is reduced, a transport speed of 30% to 90%, preferably 50% to 70% of the normal print mode is suitable.
[0020]
The second method is to increase the load between the heat roller 19b of the fixing device 23 and the pressure belt 24 more than in the normal printing mode. When the load is increased, the contact area between the heat roller 19b and the cleaning paper 27 increases, and as a result, the residual toner 28 easily transfers to the cleaning paper 27. However, if the load is excessively increased, the rotational load of the fixing device 23 increases, and abnormal noise is generated. Therefore, when increasing the load, 10% to 50% of the normal load is newly added, or preferably 10% to 50%. % To 20% may be newly added.
[0021]
The third method is a method of stopping the cleaning paper 27 while being sandwiched by the fixing device 23 when passing the paper, inverting the fixing device 23 at least once, and then rotating the cleaning paper 27 forward to convey the cleaning paper 27. . According to this method, the cleaning paper 27 is repeatedly contacted with the heat roller 19b a plurality of times, thereby increasing the number of cleanings. In the present embodiment, the first temperature is increased by simply controlling the temperature without passing the cleaning paper 27 and having a simple mechanism.
[0022]
Next, a description will be given of a fixing device cleaning process when the dirt detecting unit detects dirt due to toner adhesion on the heat roller surface, with reference to FIGS. 3 and 5. Regardless of the presence or absence of a paper jam in the fixing unit 23, when the dirt detection sensor 26 detects dirt due to the residual toner 28 on the surface of the heat roller 19b, the print data of the user is obtained by a signal from the host (not shown). Separately, the cleaning paper 27 is automatically fed to the fixing device 23, and the residual toner 28 attached to the heat roller 19b is cleaned by the cleaning paper 27 to clean the fixing device.
[0023]
In other words, the use of the detection signal of the dirt detection sensor 26 allows the residual toner 28 gradually accumulated on the heat roller 19b to be detected even if there is no paper jam in the fixing device, so that the surface of the heat roller 19b is always cleaned. Become.
[0024]
Next, the cleaning process of the fixing device when the double-sided printing unit is used will be described with reference to FIG. FIG. 6 is an explanatory diagram illustrating a state where the duplex printing unit 29 is mounted on the electrophotographic apparatus main body 16. When a paper jam occurs or when the dirt detecting means detects dirt on the heat roller 19b, the cleaning paper conveyed separately from the print data of the user by a signal from the host not shown here. 27 passes through the fixing device once, cleans the toner adhered to the heat roller 19b of the fixing device 23, and is conveyed to the duplex printing unit 29 again without being discharged. The cleaning paper 27 that has passed through the inside of the duplex printing unit 29 has the printing surface turned upside down, passes through the registration roller 11 and the transfer roller 12, is again conveyed to the fixing device 23, and is again transferred to the heat roller 19 b of the fixing device 23. The attached residual toner is cleaned and discharged. That is, the number of times of cleaning is doubled. As a result, the fixing device can be more reliably and economically cleaned with one sheet of paper.
[0025]
Further, there are the following two methods for cleaning the fixing device using the cleaning paper regardless of the presence or absence of paper jam in the fixing device and the dirt detecting unit. A method may be used.
[0026]
One is that the number of prints is detected by a sensor not shown here, and the user automatically sets at least one or more cleaning sheets separately from the user's print data by setting in advance or by each preset number of prints. This is a method in which paper is passed through a fixing device.
[0027]
The second is provided with an input unit that allows a user who has determined that the printed image is dirty to arbitrarily automatically pass at least one or more cleaning sheets to the fixing device separately from the print data. For example, when the input button 30 as shown in FIG. 7 is pressed, the cleaning paper is automatically passed to the fixing device to clean the fixing device.
[0028]
Further, as shown in FIG. 8, the fact that the cleaning paper 27 is for cleaning may be printed together with the residual toner 28 to notify the user. In FIG. 8, the fact that the paper is for cleaning is printed in Japanese, but printing in multiple languages such as English, printing in multiple languages on one sheet, and, for example, Symbols such as pictograms may be printed.
[0029]
As described above, according to this embodiment, since the surface of the heat roller of the fixing device can be maintained in a cleaned state, even if the fixing device is not provided with a cleaning mechanism, deterioration of image quality due to toner contamination of the fixing device is prevented. A long-life, maintenance-free full-color electrophotographic apparatus can be provided.
[0030]
【The invention's effect】
According to the present invention, since there is no cleaning mechanism which is a regular consumable part of the fixing device, the size of the electrophotographic apparatus is reduced, and further, there is no need to replace the regular consumable part, so that an easy-to-use electrophotographic apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory sectional view of a full-color electrophotographic apparatus according to an embodiment.
FIG. 2 is an explanatory sectional view of a conventional fixing device.
FIG. 3 is an explanatory sectional view of a fixing device of the full-color electrophotographic apparatus of the embodiment.
FIG. 4 is a flowchart of a paper jam process according to the embodiment.
FIG. 5 is a flowchart of a dirt detection processing process according to the embodiment.
FIG. 6 is an explanatory cross-sectional view of an electrophotographic apparatus with a double-sided printing unit according to the embodiment.
FIG. 7 is a perspective view of the full-color electrophotographic apparatus of the present embodiment.
FIG. 8 is an explanatory diagram of a cleaning sheet output by the full-color electrophotographic apparatus of the present embodiment.
[Explanation of symbols]
1, 2, 3, 4, developing device, 5 optical unit, 6 paper cassette, 7 paper, 8 charging device, 9 photosensitive belt, 10 transfer drum, 11 registration roller, 12 transfer roller , 13: Static eliminator, 14: Fixer, 15: Discharge roller, 16: Electrophotographic apparatus main body, 17: Feed roller, 18: Discharge tray, 19a, 19b: Heat roller, 20: Backup roller, 21: Oil bottle, 22 cleaning mechanism, 23 fixing device according to the present invention, 24 pressure belt, 25 paper jam detection sensor, 26 dirt detection sensor, 27 cleaning paper, 28 residual toner, 29 double-sided printing unit , 30 ... button.

Claims (8)

An optical device for forming a latent image, a charging device, a photosensitive device, a developing device for developing the latent image, a transfer mechanism, and a sheet that is in contact with the colored particles and melts the colored particles to form a printing medium An electrophotographic apparatus comprising a fixing device having a heat roller for fixing
The fixing device is provided with a paper jam detecting means for detecting a paper jam occurring in the fixing device, and when a paper jam occurs in the fixing device, printing is stopped upon receiving a signal from the paper jam detecting means, and the paper jam is detected. After the user removes the paper from the fixing device, one or more sheets of paper are automatically passed to the fixing device separately from the print data of the user, and the toner adhered to the heat roller caused by the paper jam is generated. An electrophotographic apparatus, wherein the image is transferred to the sheet. An optical device for forming a latent image, a charging device, a photosensitive device, a developing device for developing the latent image, a transfer mechanism, and a sheet that is in contact with the colored particles and melts the colored particles to form a printing medium An electrophotographic apparatus comprising: a fixing device having a heat roller for fixing thereon;
The image forming apparatus further includes a stain detection unit that detects toner attached to a heat roller surface of the fixing device. The heat roller surface output from the stain detection unit receives a stain detection signal due to toner adhesion, and the print data of the user is An electrophotographic apparatus, wherein one or more sheets of paper are automatically passed through a fixing device, and toner adhered to the heat roller is transferred to the sheet. An optical device for forming a latent image, a charging device, a photosensitive device, a developing device for developing the latent image, a transfer mechanism, and a sheet that is in contact with the colored particles and melts the colored particles to form a printing medium An electrophotographic apparatus comprising: a fixing device having a heat roller for fixing thereon;
The electrophotographic apparatus has an input unit for passing a sheet through the fixing unit, and a user uses the input unit to pass one or more sheets of paper to the fixing unit separately from print data. And transferring the toner adhered to the heat roller to the sheet. The electrophotographic apparatus according to any one of claims 1 to 3, wherein the paper transport speed of the fixing device when the paper is passed is 30% to 90% of the normal paper transport speed. Electrophotographic apparatus. The electrophotographic apparatus according to any one of claims 1 to 3, wherein a load of the heat roller when passing a sheet is increased by 10% to 50% than a normal load. 4. The electrophotographic apparatus according to claim 1, wherein, when the sheet is passed, the sheet is stopped in a state where the sheet is pinched by a fixing device, and the sheet is reversely conveyed at least once by the fixing device. An electrophotographic apparatus, wherein the sheet is rotated forward and the sheet is conveyed. 4. The electrophotographic apparatus according to claim 1, wherein, when the paper is passed, the paper once passed through the fixing device is turned over through a duplex printing unit, and An electrophotographic apparatus, wherein the sheet is transported again to the fixing device to pass a sheet. The electrophotographic apparatus according to any one of claims 1 to 3, wherein the ejected sheet is printed to indicate that the sheet is a cleaning sheet.

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