JPH03196173A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the erroneous detection of medium carrying and to always obtain stable medium carrying performance by providing a condensation preventive means, and preventing the dew condensation on the surface of an optical sensor. CONSTITUTION:Film shape transparent plates 4a with a water droplet attaching prevention effect are stuck on the travel plane sides of sheet of upper and lower sheet guides 24, 25 so as to cover the light emitting elements 32, 33 and the light receiving elements 30, 31 of a sensor 3. Then, the sheet is inserted from the right side of a fixing apparatus 1 to the fixing apparatus 1, and is bitten between upper and lower rollers 10, 11, and after that, it is carried to a following stacker with carrying rollers 2a, 2b. At this time, a large amount of steam is generated from the sheet, and is scattered around the optical sensor 3. However, no dew condensation at the tip of the optical sensor 3 since it is covered with an anti-fogging plate 4a. In such a way, the erroneous detection of the medium carrying can be prevented occurring, and stable medium carrying performance can be always obtained.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Conventional technology Problems to be solved by the invention Means for solving the problems (Fig. 1) Working example (a) First embodiment Explanation (Figures 2 and 3) (b
) Description of the second embodiment (Figures 4 and 5) (C)
Explanation of the third embodiment (FIG. 6) (d) Explanation of the fourth embodiment (FIG. 7) (e) Explanation of other embodiments Effects of the invention [Summary] The toner image on the medium is thermally fixed. , regarding a fixing device that is transported on a transport path.

By preventing condensation on the optical sensor surface.

The purpose is to prevent false detection of media transport and always obtain stable media transport performance.

A fixing device that fixes the toner image on the medium using heat;

In the fixing device having an optical sensor for monitoring the l* medium in the medium conveyance path after the fixing device, a dew condensation prevention means for preventing dew condensation on the surface of the optical sensor is provided.

[Industrial application field]

The present invention relates to a fixing device that thermally fixes a toner image on a medium and conveys the image on a conveyance path.

In devices that form toner images on media such as electrophotographic devices,
A fuser is used to fuse the toner image to the media.

As this fixing device, a heat fixing device using a heat roller or a flash is used because it can use plain paper and has good adhesion.

Even when such a heat fixing device is used, it is desired that the optical sensor for monitoring the conveyance of the medium does not malfunction.

[Conventional technology]

In an electrophotographic apparatus, a conveyance roller for ejection and an optical sensor using a light emitting diode and a sensor for monitoring the conveyance, particularly detecting paper jams, are provided downstream of the thermal fixing device.

Optical sensors are useful because they do not have two mechanical parts, so there is less risk of failure.

This optical sensor is provided in a conveyance path subsequent to the fixing device in order to determine whether the paper that has passed through the thermal fixing device has been successfully conveyed to the subsequent conveyance path.

[Problem to be solved by the invention]

By the way, when paper is fixed with a thermal fixing device, since the paper also contains moisture, a large amount of water vapor is generated from the paper during fixing due to the large amount of heat applied by the thermal fixing device.

The water vapor generated at this time naturally also reaches the light cell located on the subsequent conveyance path.

For this reason, the light-emitting diode on the light-emitting side of the photosensor and the sensor on the light-receiving side come into contact with air containing a large amount of water vapor, resulting in dew condensation on the surfaces of the light-emitting diode and photosensor.

This phenomenon is more likely to occur when the temperature inside the device has not risen sufficiently, such as immediately after the power is turned on, and the temperature on the surface of the sensor, etc. is low. , there is also a lot of moisture generation.

In this way, the surface of the optical sensor becomes cloudy due to condensation.

The light emitted from the light-emitting side does not reach the light-receiving side, and there was a problem in that the light sensor (; even if there was no paper, it was assumed that there was paper, and a paper jam was incorrectly detected. .

Therefore, two aspects of the present invention are to prevent dew condensation on the surface of the optical sensor (and thus to prevent erroneous detection of medium conveyance).

It is an object of the present invention to provide a fixing loss mechanism that can always obtain stable medium conveyance performance.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIG. 1, the present invention includes a fixing device 1 that fixes a toner image on a medium by heat, and a medium conveyance path 2 (== a medium conveyance path 2 after the fixing device 1), and a light source for monitoring the medium. In a fixing device having a sensor 3.

A dew condensation prevention means 4 is provided to prevent dew condensation on the surface of the optical sensor 3.

[Effect]

In the present invention, since the dew condensation prevention means 4 is provided to prevent dew condensation on the surface of the optical sensor 3, even if the amount of water vapor in the atmosphere around the optical sensor 3 increases, no dew condensation will occur on the surface of the optical sensor 3, and the medium The problem of falsely detecting a jam does not occur.

〔Example〕

(a) Description of the first embodiment FIG. 2 is a configuration diagram of the first embodiment of the present invention, and FIG. 3 is a sectional view of the main part of the first embodiment of the present invention. A cross section of the roller fuser 1 and the subsequent transport path 2 is shown.

The heat roller fixing device 1 is composed of two upper and lower rollers 10 and 11, and a halogen lamp 12 is inserted into the center of the lower heat roller 211.

Paper (=supplies heat. Upper row 210.

It is a pressure roller. Behind the fixing device 1, there are two sets of transport rows 22a and 2b, which further transport the paper coming out of the fixing device 1 to a subsequent stacker (not shown). The upper sides of the transport rollers 2a and 2b are drive rollers 20 and 21,
The lower side is the driven low (22°23).

The paper conveyance path 2 is constituted by paper guides 24 and 25 facing each other with two gaps.

The optical sensor 3 that detects paper jam is located in the paper guide 24.2.
It is attached opposite to 5. In the figure, the lower side is the light emitting section, which is composed of light emitting diodes 32 and 33, and the upper side is the light receiving side, which is composed of photosensors 30 and 31.

Light receiving side 30.31.

The tips of the sensors on both the light emitting 32 and 33 sides protrude from the paper transport surface by about 0.5 mm so that they are self-cleaned by the traveling paper (approximately 0.5 mm) from the paper guides 24 and 25.

As shown in FIG. 3, on the paper running surface side of the upper and lower paper guides 24 and 25, there is a film-like film that has the effect of preventing the adhesion of water droplets so as to cover the light-emitting elements 32, 33 and the light-receiving elements 30, 31 of the sensor 3. A transparent plate 4a is attached.

As this transparent plate 4a, for example, Polycarbonate Ace AF (trade name) is used as a protection plate made by Tsutsunaka Plastic Industry ■, and the paper guides 24 and 25 are covered with double-sided adhesive tape (
Next, the operation of this embodiment will be explained. The paper enters the fuser 1 from the right side of the fuser 1 in Figure 2, and passes through the upper and lower rows 210,
Caught in 11. The paper is then transferred to transport rollers 2a, 2
b to the subsequent stacker. At this time, a large amount of water vapor is generated from the paper and diffuses around the optical sensor 3 as well. However, since the tip of the optical sensor 3 is covered with the work shield plate 4a, no condensation occurs.

In this embodiment, since dew condensation can be prevented by covering the optical sensor 3 with the health protection plate 4a, it can be realized easily and simply.

(b) Description of Second Embodiment FIG. 4 is a block diagram of a second embodiment of the present invention, and FIG. 5 is a block diagram of main parts of the second embodiment of the present invention.

In the figure, the same thing as shown in FIG. 1, FIG. 2, and FIG. The air is blown up diagonally from below to above, and the optical sensor 3 (
The device (: always rotates when the power is turned on).

In addition, as shown in FIG. 5, the paper guide 25 (24) has a large number of long ln holes in the paper transport direction (bi-parallel), and one light emitting section 32. It is attached to the guide 25 (24).

Next, the operation of this embodiment will be explained.

The paper enters the fixing device 1 from the right side of the fixing device 1 in the figure, is caught by the upper and lower rollers 10, 11, and is then transported to the subsequent stacker by the transport rollers 2a, 2b.

At this time, a large amount of water vapor is generated from the paper, and the optical sensor 3
It also spreads around the area.

However, since the air from 71 and 4b is blown onto the surface of the optical sensor 3 through the long holes provided in the conveyance guides 24 and 25, the moist air on the surface of the optical sensor 3 is blown away, causing dew condensation on the surface of the optical sensor 3. Never.

In addition, since the fan 4b blows air diagonally upward, the air reflected by the guide 24ζ2 causes air to be blown directly onto not only the 7 sensors 30 and 31 facing downward, but also the light emitting diodes 32 and 33 facing upward. , moist air is not trapped on the surface of the optical sensor 3.

(C) Description of the third embodiment FIG. 6 is a block diagram of a third embodiment of the present invention.

In the figure, the same parts as shown in Figures 1 to 4 are:
They are indicated by the same symbols, and 4c is a heater, which is composed of two heating elements, and one which is attached to the paper guide 24 with double-sided tape or the like.
It is pasted on the side opposite to the paper conveyance path of 25 (up and down in the figure), and is always turned on if it is the power input port of the device, warming the optical sensor 3 and the surrounding air.

In this embodiment, the heater 4c is the dew condensation prevention means 4.

Next): The operation of this embodiment will be explained.

The paper enters the fuser 1 from the right side of the fuser 1 in Figure 2,
Upper and lower rows 210. IIE got caught.

Thereafter, the paper is transported to a subsequent stacker by transport rollers 2a and 2b.

At this time, a large amount of water vapor is generated from the paper, and the optical sensor 3
It also spreads around the area.

However, since the optical sensor 3 and the air around it are warmed by the heater 4C, no condensation occurs on the surface of the optical sensor 3.

(d) Description of the fourth embodiment FIG. 7 is a configuration diagram of a fourth embodiment of the present invention.

In the figure, the same parts as shown in Figures 1 to 6 are:
They are shown with the same symbol, wd is a glass window, and 2
Light emitting section 32.33. What serves as a window for the light receiving section 30.31,
A heater 4d is formed on the glass window wd to warm the glass window wd, and is provided around it so as not to interfere with the light receiving surface 30M of the light receiving portion 30 etc. as shown in FIG. 7(c). It is something that can be done.

In the example shown in FIG. 7, a heater 4C is installed in the guide 24, 25 to prevent dew condensation by increasing the temperature around the optical sensor 3, whereas the example shown in FIG. is provided, and a heater 4d is added thereto to directly warm the optical sensor 3 to prevent dew condensation on the surface of the optical sensor 3.

Even if this is done, there is no difference from the third embodiment.

Rather, this embodiment consumes less power.

(e) Description of other embodiments Although the optical sensor 3 described above is of a transmission type, it may be of a two-reflection type, and in the examples shown in FIGS. Although dew condensation prevention means are provided on both sides, either one may be used as required.

Furthermore, the fixing device 1 has been described as a heat roller fixing device.

7. A device that performs fixing using heat, such as an F-fixing device, may be used.Although a pair of optical sensors 3 are provided, one may be sufficient, and the medium is not limited to paper.

Although the present invention has been described above with reference to embodiments, the present invention can be modified in various ways according to the gist of the present invention.

These are not excluded from the present invention.

〔Effect of the invention〕

As explained above, according to the second aspect of the present invention, since the dew condensation prevention means is provided, dew condensation on the surface of the optical sensor 3 can be prevented, and even if water vapor is diffused from the medium due to the fixing operation of the heat fixing device, the light It has the effect that there is no risk of malfunction due to dew condensation on the sensor 3, and is particularly useful for high-speed electrophotographic printers that print continuously at high speed.

In the figure, l: Fixing device.

2... Conveyance path.

3... Optical sensor.

4...Means for preventing condensation.

Claims (1)

[Scope of Claims] A fixing device (1) for fixing a toner image on a medium by heat, and an optical sensor (3) for monitoring the medium in a medium conveyance path (2) after the fixing device (1). ), characterized in that the fixing device is provided with dew condensation prevention means (4) for preventing dew condensation on the surface of the optical sensor (3).