JPH0816031A - Thermally fixing apparatus - Google Patents

Abstract

PURPOSE:To provide a thermally fixing apparatus in which the temperature of a heating roller can be measured without wearing the outer circumference of the heating roller and also in which the temperature of a contacting part of the heating roller with a copy paper can be measured without inhibiting the movement of the copy paper. CONSTITUTION:Regarding an apparatus which is provided with a first rotary body 21 equipped with a heat radiating body 23 and a second rotary body 22 coming into contact with the first rotary body 21 to fix a toner image in a recording medium by leading the recording medium on which the toner image is formed between the first rotating rotary body 21 and the second rotary body 22 and heating the toner image; a non-contact-type temperature sensor to detect infrared rays and measure the temperature is provided and the temperature of the outer circumference of the first rotary body 21 can be measured by the non-contact-type temperature sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device provided in an electrophotographic apparatus.

[0002]

2. Description of the Related Art A thermal fixing device provided as a fixing device in an electrophotographic apparatus such as a laser printer has a heating roller 1, a pressure roller 2 and a heating element 3 as shown in FIG.
Some have and.

The heating roller 1 has a cylindrical shape. The heating roller 1 is horizontally arranged, and roller shafts (not shown) provided at both axial ends thereof are rotatably supported by bearings (not shown), and the roller shafts are rotated by a rotation driving device (not shown). The pressure roller 2 is horizontally arranged below the heating roller 1, and roller shafts (not shown) provided at both ends are rotatably supported by bearings (not shown) and can be displaced toward and away from the heating roller 1. This bearing is provided with elastic force toward the heating roller 1 by a spring (not shown) or the like. The upper part of the outer peripheral surface of the pressure roller 2 is constantly in pressure contact with the lower part of the outer peripheral surface of the heating roller 1.
The heating element 3 is arranged inside the heating roller 1.

Then, the heating roller 1 is rotated by the rotation driving device, and the pressure roller 2 is rotated by being driven by the heating roller 1. The heating roller 1 is heated by the heating element 3.
At the time of fixing, the recording paper 11 on which the toner image is transferred from the photosensitive drum by the transfer device is rotated by the heating roller 1
And the pressure roller 2. The toner image is conveyed by the heating roller 1 and the heating roller 1 and the pressure roller 2 at this time, and the recording paper 1
It is fixed on 1.

In this thermal fixing device, it is necessary to maintain the temperature of the heating roller 1 at a value required for fixing in order to secure stable fixing performance, and for this purpose, the temperature of the heating roller 1 is constantly maintained. And controlling the heat generation temperature of the heating element 3 so that the temperature maintains a predetermined value. For example, when the heating element 3 is a lamp, it is possible to control the value of the electric current supplied to the lamp. is necessary.

Conventionally, in the heat fixing device, the heating roller 1
In order to measure the temperature, a contact type temperature sensor 4 has been used which measures the temperature by directly contacting the temperature detecting portion with the outer peripheral surface of the heating roller 1 as shown in FIG. An example of the contact-type temperature sensor 4 is a thermistor, which detects the heating roller 1 by a temperature measuring unit that is in direct contact with the outer peripheral surface of the heating roller 1 and takes out the temperature change as a change in electric resistance to measure the temperature. It is something to do.

[0007]

However, the contact type temperature sensor has a problem that the outer peripheral surface of the heating roller is worn or deteriorated because the temperature detecting portion is in direct contact with the outer peripheral surface of the heating roller. . By the way, in a normal heat fixing device, not a method of locally heating the heating roller but a method of providing a heating element on the central axis of the heating roller to uniformly heat the entire circumferential direction of the heating roller is adopted. . In this case, the temperature of the heating roller can be measured even if the contact type temperature sensor is provided at any position in the circumferential direction of the heating roller. That is, the contact-type temperature sensor can be provided at a position that does not hinder the running of the recording paper.

However, recently, in order to shorten the start-up time of the fixing operation, it has been considered to intensively heat the portion of the heating roller that contacts the recording paper, that is, the lower portion that contacts the pressure roller. Therefore, a method has been proposed for intensively heating the recording paper contact portion of the heating roller. For example, in the heat fixing device of the above-described type, the heating element 3 is provided at a position deviated from the roller center axis to the recording paper contact portion A, or as shown in FIG. A method of condensing the light on the recording paper contact portion of the heating roller 1 is used, or a method of using a special roller that locally generates heat is used.

As described above, in the heat fixing device adopting the method of intensively heating the recording paper contact portion of the heating roller,
In order to control the temperature of the heating roller, it is necessary to measure the temperature of the recording paper contact portion of the heating roller. Therefore,
In order to measure the temperature of the heating roller using the contact-type temperature sensor, as shown in FIG. 10, the contact-type temperature sensor 4 is provided in the vicinity of the recording paper contact portion A on the outer peripheral surface of the heating roller 1 as its temperature detecting portion. The temperature of the recording paper contact portion A is measured by directly providing the recording paper.

However, providing the contact-type temperature sensor 4 in the vicinity of the recording paper contact portion A of the heating roller 1 as described above
The contact-type temperature sensor 4 is provided in the path of the recording paper 11 passing between the recording paper contact portion A of the heating roller 1 and the pressure roller 2. Therefore, when the recording paper 11 moves to pass between the heating roller 1 and the pressure roller 2 during fixing, the paper surface of the recording paper 11 slides on the contact-type temperature sensor 4 and is formed on the recording paper 11. The toner image thus formed also comes into sliding contact with the contact type temperature sensor 4 to cause a problem that the image is deteriorated.

Therefore, in order to avoid this problem, it is necessary to stop measuring the temperature of the recording paper contact portion A of the heating roller 1, and the heating roller! However, there is a problem that the method of intensively heating the contact portion of the recording paper cannot be adopted.

The present invention has been made based on the above circumstances, and the temperature of the heating roller can be measured without abrading the outer peripheral surface of the heating roller, and the recording of the heating roller can be performed without obstructing the movement of the recording paper. An object of the present invention is to provide a heat fixing device capable of measuring the temperature of a paper contact portion.

[0013]

In order to achieve the above object, a heat fixing device according to the invention of claim 1 includes a first rotating body, and a second rotating body which is in contact with the first rotating body. A heating element that heats the first rotating body, and heats the toner image by passing the recording medium on which the toner image is formed between the first rotating body and the second rotating body that rotate. The apparatus for fixing on the recording medium comprises a non-contact type temperature sensor for detecting infrared rays to measure the temperature, and the non-contact type temperature sensor measures the temperature of the outer peripheral surface of the first rotating body. Characterize.

According to a second aspect of the present invention, in the heat fixing device, the temperature of the portion of the outer peripheral surface of the first rotating body which is in contact with the second rotating body is measured by the non-contact type temperature sensor. .

[0015]

[Function] By measuring the temperature of the heating roller by using a non-contact type temperature sensor that detects infrared rays, the temperature of the heating roller can be measured without the temperature sensor abrading the outer peripheral surface of the heating roller. Is. Further, by measuring the temperature of the heating roller using the non-contact type temperature sensor, it is possible to measure the temperature of the recording paper contact portion of the heating roller without hindering the movement of the recording paper.

[0016]

Embodiments of the present invention will be described with reference to the drawings. The first embodiment will be described with reference to FIG. The thermal fixing device of this embodiment is applied to a fixing device provided in an electrophotographic apparatus such as a facsimile machine or a laser printer.

In the figure, 21 is a heating roller, 22 is a pressure roller, and 23 is a heating element. The heating roller 211 is formed of a resin having excellent heat resistance and abrasion resistance, for example, a tetrafluoroethylene resin, and has a cylindrical shape. The heating roller 21 is arranged horizontally, and roller shafts (not shown) provided at both axial ends thereof are rotatably supported by bearings (not shown), and the roller shafts are rotated by a rotation drive device (not shown). .

The pressure roller 22 is formed of a resin having excellent heat resistance and abrasion resistance, such as silicon rubber. The pressure roller 22 is horizontally arranged, for example, below the heating roller 21, and roller shafts (not shown) provided at both ends in the axial direction are rotatably supported by bearings (not shown).
The bearing is provided so as to be displaceable in the direction of approaching and separating from the heating roller 21, and an elastic force is applied to the heating roller 21 by a spring (not shown), for example. As a result, the pressure roller 2
2, the upper part of the outer peripheral surface is constantly in pressure contact with the lower part of the outer peripheral surface of the heating roller 21.

Therefore, the heating roller 21 is rotated by the rotation driving device, and the pressure roller 22 is rotated while being in contact with the heating roller 21. The heating element 23 is, for example, a halogen lamp, and is arranged inside the heating roller 21 along the central axis. In addition, a reflection plate 24 is provided inside the heating roller 21 above the heating element 23, and radiates infrared rays emitted by the heating element 23 to the lower portion of the outer peripheral surface of the heating roller 21 (contact portion with the pressure roller 22). That is, the light is reflected intensively toward the recording paper contact portion A). Therefore, the recording paper contact portion A below the heating roller 21 is intensively heated.

Further, in the figure, 25 is a non-contact type temperature sensor,
This is a non-contact type temperature sensor that detects radiated infrared rays and measures the temperature. Specifically, a thermocouple integrated temperature sensor that integrates a thermocouple, a pyroelectric temperature sensor that uses the pyroelectric effect, infrared rays. There is a semiconductor fiber type temperature sensor using a semiconductor fiber whose electric resistance changes in response to this, and the pyroelectric temperature sensor is inexpensive. The non-contact type temperature sensor 25 has a feature that it can measure the temperature by detecting infrared rays emitted from the detection target even if it is separated from the detection target, and can perform stable temperature measurement. .

The non-contact type temperature sensor 25 is radiated from the heating roller 21 while being separated from the recording paper contact portion A of the heating roller 21 in a state where its detection portion is directed toward the recording paper contact portion A of the heating roller 21. It is arranged at a position where infrared rays can be well detected, and is supported by a member (not shown). The non-contact type temperature sensor 25 is provided at a position that does not hinder the movement of the recording paper 11 and does not slide on the surface of the recording paper 11 and the toner image formed on the recording paper 11.

Non-contact type temperature sensor 25 and heating roller 21
A convex lens 26 is provided between the convex lens 26 and
Is an optical system for condensing infrared rays emitted from the recording paper contact portion A of the heating roller 21 on the detection portion of the non-contact temperature sensor 25. That is, as shown in FIG. 3, the viewing angle of the non-contact temperature sensor 25 is generally the heating roller 21.
The infrared ray radiated from the recording paper contacting portion A of the heating roller 21 is wide, and therefore the recording paper contacting portion A of the heating roller 21 is wide.
In the case of detecting the temperature of the specified portion, it is necessary to focus the infrared rays emitted from the recording paper contact portion A of the heating roller 21 on the detection portion of the non-contact type temperature sensor 25 by using an optical means. .

In this embodiment, the convex lens 26 is used as an optical means. The convex lens 26 does not hinder the movement of the recording paper 11, and the surface of the recording paper 11 and the recording paper 11 are not disturbed.
It is provided at a position where it does not come into sliding contact with the toner image formed on.

Here, the convex lens 26 has a wavelength of 1 to 20 μm.
It must be transparent to all or part of the infrared rays that are m 2. Examples of the convex lens 26 include polyethylene, calcium fluoride, barium fluoride, germanium, and zinc selenide. Among them, polyethylene is inexpensive and suitable as a material for the convex lens 26.

Further, in this embodiment, a pair of recording paper guide members 27 are provided on the recording paper exit side with respect to the heating roller 21 and the pressure roller 22 at intervals in the roller axial direction. The recording paper 11 which has been fixed by the recording paper guide member 27 is guided so as to bypass the optical system connecting the recording paper contact portion A of the heating roller 21, the convex lens 26 and the non-contact type temperature sensor 25 to move. ing. The pair of recording paper guide members 27 does not block the infrared rays received by the non-contact temperature sensor 25.

The operation of fixing by the heat fixing device having the above-mentioned structure will be described. At the time of fixing, the recording paper 11 on which the toner image is transferred is transferred from the photosensitive drum by a transfer device (not shown) provided in the electrophotographic apparatus. The recording paper 11 is transported between the rotating heating roller 21 and the pressure roller 22 which are in contact with each other. The lower portion of the outer peripheral surface of the heating roller 21 serves as a recording paper contact portion A that comes into contact with the recording paper 11 being transported. At this time, the toner image formed on the recording paper 11 moves while being in contact with the recording paper contact portion A of the heating roller 21 heated by the heating element 23, and is heated by the recording paper contact portion A of the heating roller 1. At the same time, it is sandwiched between the recording paper contact portion A of the heating roller 1 and the upper portion of the outer peripheral surface of the pressure roller 2, and is pressurized and fixed on the recording paper 11.

Here, the recording paper contact portion A of the heating roller 21.
Infrared rays are emitted from the infrared ray, but this infrared ray is convex lens 26.
The light is focused on the detection part of the non-contact temperature sensor 25. The non-contact type temperature sensor 25 measures the temperature of the recording paper contact portion A of the heating roller 21 according to the state of the received infrared rays. The infrared rays radiated from the recording paper contact portion A of the heating roller 21 are condensed by the convex lens 26 so that the non-contact type temperature sensor 25 can measure the temperature of the recording paper contact portion A accurately. Further, the recording paper 11 that has been fixed
Is guided by a pair of recording paper guide members 27 so as to bypass the optical system connecting the recording paper contact portion A of the heating roller 21, the convex lens 26 and the non-contact temperature sensor 25, and the temperature of the recording paper 11 is measured. Does not interfere with.

The non-contact type temperature sensor 25 outputs temperature information to a control circuit (not shown). The control circuit controls the heat generation temperature of the heating element 3 based on the temperature information from the non-contact temperature sensor 25 so that the temperature of the heating roller 21 maintains a predetermined value. For example, when the heating element 3 is a lamp, the value of the electric current supplied to the lamp is controlled.

Since the non-contact temperature sensor 25 measures the temperature of the recording paper contact portion A at a position distant from the recording paper contact portion A of the heating roller 21, the temperature of the recording paper contact portion A is measured. The temperature sensor 25 does not slidably contact the outer peripheral surface of the heating roller 21 to cause wear or damage. Also,
The problem that the non-contact temperature sensor 25 slides on the toner image on the recording paper 11 to deteriorate the image does not occur. Therefore, in the heat fixing device, the heating roller 23 is heated by the heating element 23.
It is possible to carry out various methods of intensively heating one recording paper contact portion A.

The second embodiment will be described with reference to FIG. 4, the same parts as those in FIG. 1 are designated by the same reference numerals. In this embodiment, a concave mirror 28 is used to guide the infrared rays emitted from the recording paper contact portion A of the heating roller 21 to the detection portion of the non-contact type temperature sensor 25 to collect the infrared rays. That is, the concave mirror 28 is provided at a position apart from the heating roller 21 and capable of receiving and condensing infrared rays emitted from the recording paper contact portion A of the heating roller 21, and the non-contact temperature sensor 25 is focused on the concave mirror 28. It is provided at the corresponding position. The concave mirror 28 needs to absorb little infrared rays. For example, a mirror made of glass absorbs infrared rays, and a mirror whose reflection surface is made of metal absorbs little infrared rays. Non-contact temperature sensor 25 and concave mirror 28
Is provided at a position that does not hinder the movement of the recording paper 11 and does not slide on the surface of the recording paper 11 and the toner image formed on the recording paper 11.

In this embodiment, infrared rays radiated from the recording paper contact portion A of the heating roller 21 are focused on the detection portion of the non-contact type temperature sensor 25 by the concave mirror 29. FIG. 5 shows a third embodiment. This embodiment also uses the heating roller 21.
The concave mirror 29 is used to collect the infrared rays radiated from the recording paper contact portion A of FIG. 5, the same parts as those in FIG. 1 are designated by the same reference numerals.

FIG. 6 shows a fourth embodiment. In this embodiment, the same parts as those in FIG. 1 are designated by the same reference numerals in FIG. In this embodiment, the infrared rays radiated from the recording paper contact portion A of the heating roller 21 are irradiated with the glass fiber 30.
Is used to guide to the detection section of the non-contact temperature sensor 25. That is, one end of the glass fiber 30 is directed to the recording paper contact portion A of the heating roller 21, and the other end is directed to the detection portion of the non-contact temperature sensor 25. Glass fiber 30
Is provided at a position that does not hinder the movement of the recording paper 11 and does not slide on the surface of the recording paper 11 and the toner image formed on the recording paper 11. As the optical means, the lens, the mirror and the glass fiber may not be used individually but may be used in combination with each other.

In FIG. 7, the recording paper 11 on which the fixing has been completed is brought into contact with the recording paper A of the heating roller 21 and the non-contact temperature sensor 25.
17 shows another embodiment (fifth embodiment) of a recording paper guiding member for guiding the optical system connecting the two so as to bypass the optical system. The recording paper guiding member 31 used in this embodiment is arranged over the entire axial direction of the heating roller 21 and is indicated by a member (not shown). A hole 32 for passing infrared rays emitted from the recording paper contact portion A of the heating roller 21 is formed in the center of the recording paper guide member 31. The infrared light that has passed through the hole 32 is guided to the detection unit 7 of the non-contact temperature sensor 25 by using optical means such as a lens, a mirror, and a glass fiber (not shown).

In the embodiments described so far, the heating paper is used to intensively heat the recording paper contact portion of the heating roller. However, the portion of the heating roller that is intensively heated is applied to the recording paper contact portion of the heating roller. It is not limited and may be another part. Further, the method of intensively heating the recording paper contact portion of the heating roller is not limited to the method of using the reflection plate, and the heating element is locally arranged near the portion to be intensively heated. There are various methods such as using a special roller that generates heat.

The present invention is not limited to the type in which a part of the heating roller is heated intensively, but can be applied to a type in which the entire heating roller 21 is heated in the circumferential direction by the heating element 23 as shown in FIG. 8 ( Sixth embodiment). In this case, the non-contact type temperature sensor 25 is provided at an arbitrary place. In FIG.
The same parts as are indicated by the same reference numerals. It should be noted that the present invention is not limited to the above-described embodiments, but can be modified and implemented in various ways.

[0036]

As described above, according to the heat fixing device of the first aspect of the invention, the temperature of the heating roller is measured by using the non-contact type temperature sensor which detects the infrared rays to measure the temperature. The temperature sensor can measure the temperature of the heating roller without abrading the outer peripheral surface of the heating roller.

According to the heat fixing device of the second aspect of the present invention, the temperature of the heating roller is measured by using the non-contact type temperature sensor, so that the recording paper of the heating roller is not hindered from moving. It becomes possible to measure the temperature of the contact portion, and therefore various methods of intensively heating the recording paper contact portion of the heating roller can be adopted.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a heat fixing device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a heat fixing device of the embodiment.

FIG. 3 is a diagram showing a viewing angle of a non-contact temperature sensor.

FIG. 4 is a diagram showing a heat fixing device according to a second embodiment.

FIG. 5 is a diagram showing a heat fixing device according to a third embodiment.

FIG. 6 is a diagram showing a heat fixing device according to a fourth embodiment.

FIG. 7 is a diagram showing a heat fixing device according to a fifth embodiment.

FIG. 8 is a diagram showing a heat fixing device in a sixth embodiment.

FIG. 9 is a diagram showing an example of a conventional heat fixing device.

FIG. 10 is a diagram showing another example of a conventional heat fixing device.

[Explanation of symbols]

21 ... Heating roller, 22 ... Pressure roller, 23
... Heating element, 25 ... Non-contact temperature sensor,
26 ... Convex lens, 27 ... Guide member, 28 ...
Concave mirror, 29 ... Concave mirror, 31 ... Guidance member.

Claims (2)

[Claims] 1. A recording medium on which a toner image is formed, comprising a first rotating body, a second rotating body in contact with the first rotating body, and a heating element for heating the first rotating body. In a device for heating the toner image to fix it on the recording medium by passing it between the first rotating body and the second rotating body that rotate, a non-contact type that detects infrared rays and measures the temperature. A temperature sensor is provided, and the first non-contact temperature sensor
A thermal fixing device characterized by measuring the temperature of the outer peripheral surface of the rotating body. 2. The heat according to claim 1, wherein the non-contact temperature sensor measures the temperature of a portion of the outer peripheral surface of the first rotating body which is in contact with the second rotating body. Fixing device.