JPH04166968A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the leakage of water from paper due to dew condensation by providing heating elements and a temperature sensor outside a pair of upper and lower plates which form a passage for paper on which images have been fixed, and holding constant the temperature range of the paper passage. CONSTITUTION:A heating roller 2 and a pressing roller 3 in a fixing device 1 hold paper P between them while being rotated and heat and press the paper P to stably fix a toner image thereon and then push out the paper P to an exit 1a, and heating elements 6, 6 are provided outside upper and lower guide plates 4a, 4b forming a passage 5 through which the paper P on which the image has been fixed is passed and the outside of each heating element is sealed by a sealing member 7, 7. Air in the passage 5 is warmed by heat from the heating elements 6, 6. A temperature sensor 8 is provided near the passage 5 and when the temperature near the passage is lowered to below a set range electricity is transmitted to each heating element 6, 6 to heat the same and when the temperature is raised to above the set range the electricity is stopped so as to control the temperature near the passage 5 as needed, thus preventing dew condensation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fixing device, and more specifically to a fixing device for an image forming apparatus, which is designed to prevent paper that has undergone fixing processing from getting wet or jammed. The present invention relates to a fixing device.

[Prior Art] Conventionally, in the fixing device of the copying machine t4, there is a humid and heated air layer inside the fixing device, a low-temperature air layer surrounding the fixing device, and an L value that is suddenly raised when paper passes through it. Due to the large temperature difference between the paper and the paper, dew condensation often occurs and the paper becomes wet.

This water-wetting of the paper greatly reduces the quality of the formed image and impairs the conveyance of the paper, so it must be avoided as much as possible.

As a countermeasure against this problem, Japanese Patent Application Laid-Open No. 154867/1983 uses a fan 11 to prevent paper flow at the exit of the fixing device, as shown in FIG.
The dew condensation phenomenon on the paper P after fixing is eliminated by blowing air into the surrounding area to create an air current and disturb the air, and by averaging the temperature of the air layer with high and low temperature differences to create air with no temperature difference. There is.

[Problem to be Solved by the Invention] However, when the fan 11 is used in this way, if the sheet size is small and thin, the tip of the sheet 111P will float up due to the airflow generated by the fan, and the ejection roller pair 9 There was an issue where paper jams could occur due to poor jamming.

The present invention aims to solve such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides the following fixing device.

That is, the present invention includes two upper and lower guide plates that are provided between the fixing device exit and the discharge roller and form a fixed paper path, and a heating element that is disposed on the outside of each guide plate. a sealing member that further seals and holds the heating elements from the outside; and a sealing member disposed near the guide plate;
The fixing device is characterized in that it includes a temperature sensor that detects the temperature in the vicinity thereof.

[Function] In the configuration described in item 2, when the sensor detects a temperature below a certain level, the heating element is heated by energizing to raise the temperature of the air in the upper and lower guide plates.

When the sensor detects that the temperature has exceeded a certain level, the power to the heating element is stopped, thereby maintaining the temperature range of the paper path at a constant level and reducing the temperature difference in the air within the paper path. lose.

[Example] Regarding an example of the present invention, how the configuration of the present invention is actually embodied will be described below with reference to the drawings, together with its operation.

FIG. 1 is a front internal explanatory view of one embodiment of the present invention, and in the figure, 1 is a fixing device of an image forming apparatus.

Inside this fixing device 1-, there is a heat roller 2 that heats the paper P.
There is also a pressure roller 3 that presses against the heat roller 2 from below, and these rollers 2 and 3 grip the paper P while rotating as shown by the arrows, and heat and press the paper P to release the same paper. After the upper toner image is stably fixed on the paper, it is pushed out to the exit 1a on the fixing device.

This exit 1a has an upper guide plate 4a and a lower guide plate 4b, and these upper and lower guide plates 4a and 4b constitute a passage 5 through which the fixed paper P passes.

The upper and lower guide plates 4a-4b constituting this passage 5 are provided with heating elements 6, 6 that generate heat electrically on the outside, and the outsides of the heating elements 6, 6 are sealed with seal members 7, 7, The heating elements 6, 6 are fixed to the double-sided power plates 4a, 4b, respectively, with the same seals 7, 7.

A passage 5 formed by the upper and lower guide plates 4a and 4b
The air inside is heated by the upper and lower heating elements 6.

Further, a temperature sensor 8 is provided near this passage 5,
This temperature sensor 8 detects, for example, a temperature of 15 degrees Celsius near the passage.
When the temperature is below 20 degrees Celsius, the heating elements 6 and 6 are energized and heated, and when the temperature is 20 degrees Celsius or above, the electricity is turned off, thereby appropriately controlling the temperature near the paper path 5 and preventing the formation of dew condensation. ing.

- At the downstream end of the paper path 5, there is a pair of discharge rollers 9 that rotate as indicated by the arrows, and the paper P discharged from the pair of discharge rollers 9 is discharged onto a discharge tray 107.

FIG. 2 is a perspective explanatory view of the guide plate of the same embodiment, in which a meandering groove 40 is provided on the lower surface of the aluminum lower guide plate 4b.
A linear heating element 6 is embedded in the meandering groove 4c, covered with a seal member 7 from the outside, and fixed to the lower guide plate 4b.

FIG. 3 is a view taken along the arrow A-A in FIG. The side sectional view shows that it is stably held.

The reason why the lower guide plate 4b is provided with the groove 4c and has a meandering shape as shown in FIG. 2 is to increase the contact area with the heating element 6 and efficiently guide the heat of the heating element 6. This is to convey information to board 4)+. Incidentally, it goes without saying that the upper guide plate 4a is also constructed in the same manner.

As described in the embodiments above, the present invention provides heating elements on the upper and lower guide plates constituting the paper path between the fixing device exit and the discharge roller, covers the heating elements with a knoll member, and There is no need to apply a strong air current to the paper that has been fixed by the fixing device, and the paper can pass through a passageway where the temperature is evenly controlled and there is no risk of condensation, so even if the paper is small, Even thin sheets can be conveyed to the ejection roller while maintaining a stable body without causing gaps between old sheets.

[Effects of the Invention] As described above, according to the present invention, the upper and lower two guide plates forming the fixed paper path between the fixing device exit and the ejection roller are provided with heating elements, respectively. Furthermore, a sealing member that holds the seal from the outside, Equipped with an FA temperature sensor, the air in the paper path is kept at an appropriate temperature and in good condition with little temperature difference, and since there is no dew condensation, the paper does not need water, reducing the occurrence of transport defects. Defense L
You can do L.

Also, there is no need to apply a strong airflow from a fan = 7-, so small or thin paper will not float up.
While maintaining a stable state, the leading edge of the paper is guided to the edge roller, which has the effect of preventing paper jams and the like.

[Brief explanation of the drawing]

Fig. 1 is a front internal explanatory view of an embodiment of the present invention, Fig. 2 is a perspective explanatory view of a guide plate of the same embodiment, Fig. 3 is a view taken along arrow A-A in Fig. 2, and Fig. 4 is an explanatory diagram of a conventional example. 1 Fixing device, 4a-J guide plate, 4b Lower Kai! - board, 5 paper path, 6 heating element, 7 sealing member, 8 temperature sensor, 9 υF output roller.

Claims (1)

[Claims] Two upper and lower guide plates are provided between the exit of the fixing device and the ejection roller and form a path for fixed paper, and heating elements are installed on the outside of each guide plate. A fixing device further comprising: a sealing member for sealing and holding from the outside; and a temperature sensor disposed near the guide plate to detect a temperature in the vicinity.