JP2006215357A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent transfer/fixing failure and a jam during printing of the rear face of paper by preventing dew condensation from occurring in the vicinity of a paper feed roller and a paper guide which are disposed in a paper passage where paper right after passing a heating roll passes, by the use of a low cost technique. <P>SOLUTION: A printer has a fixing device which has a heating roll and a pressure roll disposed in pressurized contact with the heating roll, holds printing paper holding an unfixed toner image between the heating roll and the pressure roll and conveys the paper, and fixes the unfixed toner image to the printing paper. In the passage where paper right after passing the heating roll passes, the printer includes an area of an intermediate temperature between the temperature of the heat roll and that of the external part of the printer. The printer has an exhaust means that discharges air to the outside of the fixing device from the intermediate temperature area while keeping the temperature of the intermediate temperature area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printer using an electrophotographic system or the like, and relates to a fixing device using a thermal fixing system.

  The electrophotographic printing apparatus exposes print data to the photoconductive surface of the photoconductor by an optical unit, generates a potential difference on the surface of the photoconductor, and develops the toner, which is powder ink, with a developing machine. Then, the image is transferred to the printing paper, and the printing paper is sent out to the fixing device by the tractor.

  As shown in FIG. 3, the toner 3 on the printing paper 5 sent to the fixing device receives heat from the back surface of the printing paper 5 from a heating plate 8 having a heater inside and starts to soften. The toner 3 that has started to be softened is fixed on the printing paper 5 by being nipped and conveyed by a heating roll 9 and a pressure roll 10 each having a heater therein. The fixed printing paper 5 passes through the paper feed roller 11, is sent out to the paper folding section, and is folded.

  When double-sided printing is performed by the printing apparatus having the above-described configuration, the printing sheet 5 is sent out of the printing apparatus without performing folding in the folding unit, and printing on the subsequent process side of the two printing apparatuses arranged in series is performed. Printing paper 5 is fed into the apparatus, and the back side is printed.

  In the fixing device that is heated and pressed by the heating roll 9 and the pressure roll 10 as in the above-described configuration, and is nipped and conveyed, the paper feed roller 11 provided in the paper path immediately after passing through the heating roll 9 and the paper guide installed in the vicinity thereof. In this case, the moisture evaporated from the printing paper 5 results in a high humidity environment.

  In some cases, a heating member 14 is provided in the paper path immediately after the heating roll 9 in order to alleviate the high humidity environment in the paper path immediately after passing through the heating roll 9 (see, for example, Patent Document 1).

JP 2001-5317 A

  The conventional fixing device has the following problems because the paper feed roller disposed in the paper path immediately after passing through the heating roll and the nearby paper guide are in a high humidity environment.

  1. Water droplets are generated by condensation on the paper feed roller and the paper guide installed in the vicinity exposed to a high humidity environment, and the water droplets adhere to the printing paper, causing irregularities on the printing paper, and printing on the back side by the irregularities. Inadequate transfer and fixing problems occur.

  2. Water droplets are generated by dew condensation on the paper guide exposed to a high humidity environment, and the friction coefficient between the paper guide and the paper increases to generate JAM. Further, when a heating member is provided in the paper path immediately after the heating roll, the same problem occurs because there is no means for exhausting air in a high humidity environment to the outside of the printing apparatus.

  In addition, there were the following problems.

  1. Since the heating member and the temperature control of the heating member are provided, the apparatus price is increased and complicated control is required.

  2. The heating member increases the power consumption of the apparatus and increases the size of the apparatus as the power supply capacity increases.

  An object of the present invention is to prevent condensation near the paper feed roller and the paper guide disposed in the paper path immediately after passing through the heating roll by an inexpensive method, and to prevent transfer / fixing failure and JAM during backside printing. is there.

  The object is to provide an intermediate temperature region outside the heating roll and the printing apparatus in the paper path immediately after passing through the heating roll, and to exhaust air from the intermediate temperature region to the outside of the fixing device while maintaining the intermediate temperature region. This is achieved by providing

  According to the present invention, an intermediate temperature region outside the heating roll and the printing apparatus is provided in the paper path immediately after passing through the heating roller, and the temperature of the paper feed roller and the paper guide is heated by maintaining the intermediate temperature region. It can be kept at an intermediate temperature outside the roll and the printer, making it difficult for condensation to occur, and high-humidity air that continues to evaporate from the paper can be exhausted, resulting in water droplet adhesion due to condensation and water absorption of the paper in a high-humidity environment. Transfer / fixing defects during backside printing and JAM due to water droplets condensed on the paper guide can be prevented.

  As means for providing an intermediate temperature region outside the printing roll and the printing roll in the paper path immediately after passing through the heating roll, heat is taken from the heating roll and the exhaust air from the intermediate temperature region is oriented along the paper running direction. Realized by.

  An embodiment according to the present invention will be described with reference to FIG.

  In FIG. 1, print data is exposed to a photoconductive surface 1 having photoconductivity by an optical unit 2 to generate a potential difference on the photoconductor surface 1, and toner 3 that is powder ink is developed by a developing device 4. Next, the image is transferred from the photoreceptor surface 1 to the printing paper 5, and the printing paper 5 is sent out to the fixing device 7 by the tractor 6. The toner 3 on the printing paper 5 sent to the fixing device 7 starts to soften by receiving heat from the back surface of the printing paper 5 from a heating plate 8 having a heater inside. The toner 3 that has started to soften is fixed on the printing paper 5 by being nipped and conveyed by a heating roll 9 and a pressure roll 10 each having a heater therein. A paper feed roller 11 and a paper guide 12 for sending the printing paper 5 that has passed through the heating roll 9 to the paper folding unit 13 are provided in the area after passing through the heating roll 9 to the outside of the fixing device 7.

  In the printing apparatus having this configuration, the sheet folding unit 13 folds the sheet, and the folding unit 13 does not fold out the printing sheet 5 to the outside of the printing apparatus. There is a usage method in which the printing paper 5 is sent to a post-process side printing apparatus and printing on the back side is performed.

  A blower 15 and a blower 16 are provided in the vicinity of the paper feed roller 11 and the paper guide 12. The blower 16 has a duct 17 having an air inlet in the direction of the heating roll 9, and the high-temperature air in the vicinity of the heating roller 9 is supplied to the paper. It is drawn near the feed roller 11. The heating roll 9 is about 200 ° C., and the outside of the printing apparatus is about 25 ° C. The vicinity of the paper feed roller 11 and the paper guide 12 disposed in the paper path immediately after passing through the heating roll 9 is an intermediate temperature between the temperature of the heating roll 9 and the temperature outside the printing apparatus, and is about 45 ° C. to 65 ° C. The blower 15 and the blower 16 exhaust to the outside of the fixing device 7. The blower 15 draws high-temperature air in the vicinity of the heating roll 9 near the paper feed roller 11 and also exhausts high-humidity air to the outside of the fixing device, and has two functions. The angle X of the blower 15 is 45 ° ± 5 °, and the angle Y of the blower 16 is 25 ° ± 5 °. The blowing direction of the blower 15 and the blower 16 is the forward direction with respect to the traveling direction of the printing paper. Air is blown along with the flow of wind due to the progress of the paper during operation, thereby improving exhaust efficiency.

  Although not shown, three blowers 15 and six blowers 16 are provided in the paper width direction. The quantity of the blower 15 and the blower 16 can be changed within a range of 1 to 5 depending on the printing speed.

  The blower 15 and the blower 16 operate during a printing operation and in an apparatus standby state.

  With the above configuration, an intermediate temperature region outside the heating roll 9 and the printing apparatus can be provided in the paper path immediately after passing through the heating roll 9, and the temperatures of the paper feed roller 11 and the paper guide 12 can be printed with the heating roll 9. It is possible to maintain an intermediate temperature outside the apparatus and accumulate high-humidity air that continues to evaporate from the paper during the printing operation while preventing water droplets from adhering to the paper feed roller 11 and the paper guide 12 due to condensation in a high-humidity environment. This can be prevented. As a result, it is possible to prevent transfer / fixing defects during backside printing and JAM due to water droplets condensed on the paper guide 12.

  In the embodiment shown in FIG. 2, the exhaust air from the blower 18 and the blower 19 is not directed directly to the printing paper, and the angles Z1 and Z2 are 25 ° ± 5 °. In this configuration, the effect of preventing water content of the paper by the high-humidity exhaust air can be obtained, and the same effect can be obtained.

It is a side view of the present invention. It is a side view of the present invention. It is the side view which showed the prior art.

Explanation of symbols

1. 1. Photoconductor surface Optical part 3. Toner 4. Developer 5. Printing paper Tractor 7. Fixing device 8. Heating plate 9. Heating roll 10. Pressure roll 11. Paper feed roller 12. Paper guide 13. Paper folding unit 14. Heating member 15. Blower 16. Blower 17. Duct 18. Blower 19. Blower

Claims (5)

  A heating roll and a pressure roll provided so as to be capable of being pressed against the heating roll; the printing paper holding an unfixed toner image is sandwiched and conveyed between the heating roll and the pressure roll; In a printing apparatus having a fixing device for fixing a toner image on the printing paper, an intermediate temperature region outside the heating roll and the printing device is provided in a paper path immediately after passing through the heating roll, and the temperature in the intermediate temperature region is set. A fixing device comprising exhaust means for exhausting air from the intermediate temperature region to the outside of the fixing device while maintaining the temperature.   The fixing device according to claim 1, wherein an intermediate temperature region outside the heating roll and the printing apparatus is formed by taking heat of the heating roll into a paper path immediately after passing through the heating roll.   The fixing device according to claim 2, further comprising a blower for taking in heat of the heating roll in a paper path immediately after passing through the heating roll, and the blower also serves as an exhaust function to the outside of the fixing device.   The fixing device according to claim 1, wherein the exhaust from the intermediate temperature region to the outside of the fixing device is directed along the paper travel. The fixing device according to claim 1, wherein the exhaust air from the intermediate temperature region to the outside of the printing apparatus is not directed to the printing paper.

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