JP2003287977A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of always accurately measuring the surface temperature of a heating roller and preventing the deterioration of a temperature sensor, and to provide an image forming apparatus. <P>SOLUTION: The thermal fixing device 33 is equipped with a temperature measuring unit 55 for measuring the surface temperature of the heating roller 47. The unit 55 is constituted of a temperature detection part 65 being an infrared sensor, a duct 67 guiding infrared rays emitted from the surface of the roller 47 to the detection part 65 and a heat insulating member 69 provided between the duct 67 and the detection part 65 and having the large resistance of heat conduction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device and an image forming apparatus including the fixing device.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a laser printer has a thermal fixing device for thermally fixing a toner image transferred onto a sheet. This heat fixing device has a heating roller and a pressure roller which are arranged to face each other, and the toner image is transferred while the sheet on which the toner image is transferred passes between the heating roller and the pressure roller. Heat fix on paper.

The heating roller of such a heat fixing device is usually equipped with a heater such as a halogen lamp and a temperature sensor for detecting the surface temperature of the heater. Then, the heating roller controls ON / OFF of the heater by detecting the surface temperature by the temperature sensor to maintain a predetermined heat fixing temperature.

As a temperature sensor used in the heat fixing device, there is a contact type temperature sensor such as a thermistor which comes into contact with a heating roller. However, this contact-type temperature sensor has a problem that the toner adheres to the temperature sensor to deteriorate the detection accuracy, and the toner accumulated on the temperature sensor peels off and damages the heating roller, or drops on the paper. There was the problem of becoming dirty.

Therefore, various non-contact type temperature sensors have been proposed which are arranged at a predetermined distance from the heating roller and measure the temperature using infrared rays emitted from the surface of the heating roller. When this non-contact type temperature sensor is used, the infrared ray emitted from the part other than the surface of the heating roller is detected between the heating roller and the non-contact type temperature sensor so that the temperature detection error does not occur. A conduit is provided for guiding infrared light to the.

[0006]

However, in the above-mentioned non-contact type temperature sensor, the heat generated by the heating roller is transferred to the non-contact type temperature sensor via the conduit, and the temperature of the non-contact type temperature sensor is gradually increased. Could rise. in this case,
Since the non-contact type temperature sensor usually has low heat resistance, there are problems that the temperature detection accuracy is lowered and the non-contact type temperature sensor is deteriorated.

Further, in the non-contact type temperature sensor, if the mounting position of the conduit with respect to the heating roller is deviated, the amount of infrared rays reaching the non-contact type temperature sensor fluctuates, and the temperature detection accuracy deteriorates. There was a problem. The present invention has been made in view of the above points, and it is an object of the present invention to provide a fixing device and an image forming apparatus capable of always measuring the surface temperature of a heating roller with high accuracy and suppressing deterioration of a temperature sensor. To aim.

[0008]

Means for Solving the Problems and Effects of the Invention (1) The invention of claim 1 is a fixing means for heating and fixing a medium to be fixed to a fixing medium; a containing means for containing the fixing means; A fixing device including a temperature detecting means for measuring the surface temperature of the fixing means based on infrared rays emitted from the surface of the fixing means, and a light guiding means for guiding the infrared ray emitted by the fixing means to the temperature detecting means. In the above, the temperature detecting means is arranged outside the accommodating means, and the light guiding means is provided with a hollow portion, which is a path of infrared rays, and a reflection portion provided facing the hollow portion so as to reflect the infrared rays. Face and
The gist is a fixing device characterized by including.

In the fixing device of the present invention, since the temperature detecting means is arranged outside the accommodating means, even if the temperature inside the accommodating means rises due to the heat emitted by the fixing means, the temperature of the temperature detecting means is increased. Is hard to rise. Therefore, the temperature detection unit can accurately measure the temperature of the fixing unit. Further, it is possible to suppress deterioration of the temperature detecting means.

Further, the fixing device of the present invention is provided with the light guide means having the hollow portion and the reflecting surface, and the infrared rays radiated from the surface of the fixing means are reflected by the reflecting surface while the hollow portion is formed. After that, it can be led to the temperature detecting means. As a result, even if the temperature detecting means is separated from the fixing means, the infrared rays emitted from the surface of the fixing means can be guided to the temperature detecting means in an amount sufficient for temperature detection.

Further, since the fixing device of the present invention is provided with the light guiding means, the infrared rays radiated by the fixing means can be guided to the temperature detecting means, so that the measuring accuracy of the temperature detecting means is high. (2) According to the invention of claim 2, in a heat conduction path from the heat generated by the fixing means to the temperature detecting means via the light guiding means, a high heat conduction resistance portion is provided to inhibit the heat conduction. The fixing device according to claim 1 is characterized in that.

In the fixing device of the present invention, since the heat conduction path has the high heat conduction resistance portion, heat conduction to the temperature detecting means is suppressed. Therefore, the temperature of the temperature detecting means is less likely to rise, and the temperature detecting means can measure the surface temperature of the fixing means with higher accuracy. Further, the deterioration of the temperature detecting means can be further suppressed.

(3) According to a third aspect of the invention, the surface temperature of the fixing means is determined based on the fixing means for heating and fixing the medium to be fixed on the fixing medium and the infrared rays radiated from the surface of the fixing means. Temperature detecting means for measuring, and light guiding means for guiding infrared rays emitted by the fixing means to the temperature detecting means,
In a fixing device including: a heat conduction path through which heat generated by the fixing means reaches the temperature detecting means through the light guiding means, a high heat conduction resistance portion that inhibits the heat conduction is provided. The fixing device is the main point.

In the fixing device of the present invention, since the heat conduction path has the high heat conduction resistance portion, heat conduction from the fixing means to the temperature detecting means is suppressed. Therefore, the temperature of the temperature detecting unit is unlikely to rise, and the temperature detecting unit can accurately measure the surface temperature of the fixing unit. Further, it is possible to suppress deterioration of the temperature detecting means.

(4) The invention according to claim 4 provides the fixing device according to claim 3, characterized in that the fixing device includes a housing means for housing the fixing means. In the present invention, the fixing means is housed in the housing means. For example, temperature detecting means can be attached to the housing means.

(5) The invention according to claim 5 provides the fixing device according to any one of claims 2 to 4, characterized in that the high heat conduction resistance portion is a portion made of a heat insulating material. . In the present invention, by providing the high heat conduction resistance portion made of a heat insulating material in the heat conduction path, heat conduction to the temperature detection means is suppressed, and the temperature of the temperature detection means is unlikely to rise.
As a result, the temperature detecting unit can measure the temperature of the fixing unit with high accuracy, and the deterioration of the temperature detecting unit can be suppressed.

(6) A sixth aspect of the invention provides a fixing device according to the fifth aspect, wherein the heat insulating material is a material having a thermal conductivity of 10 W / mK or less.
In the present invention, since the heat conductivity of the heat insulating material is 10 W / mK or less, the heat conduction in the heat conduction path is further suppressed, and the temperature rise of the temperature detecting means can be further suppressed. As a result, the temperature detecting unit can measure the temperature of the fixing unit with high accuracy, and the deterioration of the temperature detecting unit can be further suppressed.

(7) The invention according to claim 7 provides the fixing device according to claim 5, wherein the heat insulating material is a heat resistant resin. In the present invention, by providing the heat-insulating member made of heat-resistant resin in the heat-conducting path as the high-heat-conducting resistance portion, it is possible to suppress heat conduction to the temperature detecting means and suppress temperature rise of the temperature detecting means. As a result, the temperature detecting unit can measure the temperature of the fixing unit with high accuracy, and the deterioration of the temperature detecting unit can be suppressed.

(8) The invention of claim 8 is characterized in that the portion made of the heat insulating material has a length of 0.1 mm or more along the heat conduction path. The gist of any of the fixing devices is described.

In the present invention, since the length of the portion made of the heat insulating material is 0.1 mm or more along the heat conduction path, the heat conduction in the heat conduction path is suppressed and the temperature rise of the temperature detecting means is suppressed. Is even higher. As a result, the temperature detection unit can measure the temperature of the fixing unit with higher accuracy, and further suppress deterioration of the temperature detection unit.

(9) The invention of claim 9 is characterized in that the high heat conduction resistance portion is a portion of the heat conduction path separated by air. The gist of the fixing device is described.

The present invention exemplifies the high heat conduction resistance portion. In the present invention, the high heat conduction resistance portion is provided with a portion separated by air having a low heat conductivity in the heat conduction path, so that the heat conduction to the temperature detection means is suppressed and the temperature rise of the temperature detection means is suppressed. be able to. As a result, the temperature detecting unit can measure the temperature of the fixing unit with high accuracy, and the deterioration of the temperature detecting unit can be suppressed.

(10) According to a tenth aspect of the present invention, the portions separated by the air are along the heat conduction path,
The gist of the fixing device according to claim 9 is that the fixing device has a length of 0.1 mm or more.

In the present invention, since the length of the portion separated by air is 0.1 mm or more along the heat conduction path, heat conduction in the heat conduction path is suppressed, and the temperature of the temperature detecting means is reduced. The effect of suppressing the rise is even higher. As a result, the temperature detection unit can measure the temperature of the fixing unit with higher accuracy, and further suppress deterioration of the temperature detection unit.

(11) According to the eleventh aspect of the present invention, the high heat conduction resistance portion is such that, in the heat conduction path, the cross-sectional area of a plane perpendicular to the heat conduction direction is larger than the cross-sectional areas of the front and rear portions thereof. The fixing device according to any one of claims 2 to 4, which is a reduced portion.

In the present invention, in the heat conduction path, there is a portion having a small cross-sectional area in the plane perpendicular to the heat conduction direction, so that heat conduction is suppressed. Therefore, in the present invention, by providing the above-mentioned portion as the high heat conduction resistance portion, it is possible to suppress heat conduction to the temperature detecting means and suppress an increase in temperature of the temperature detecting means. As a result, the temperature detecting unit can measure the temperature of the fixing unit with high accuracy, and the deterioration of the temperature detecting unit can be suppressed.

(12) The invention of claim 12 is characterized in that the high heat conduction resistance portion is provided between the light guide means and the temperature detection means. The fixing device described in Crab is the gist.

According to the present invention, by providing the high heat conduction resistance portion between the light guiding means and the temperature detecting means, the heat conduction from the light guiding means to the temperature detecting means is suppressed and the temperature rise of the temperature detecting means is suppressed. can do. As a result, the temperature detecting unit can measure the temperature of the fixing unit with high accuracy, and the deterioration of the temperature detecting unit can be suppressed.

(13) The invention according to claim 13 is the fixing device according to any one of claims 2 to 11, characterized in that the high heat conduction resistance portion is provided in the light guide means. And In the present invention, by providing the light guide means with the high thermal conductive resistance portion, it is possible to suppress heat conduction from the fixing means to the temperature detection means via the light guide means, and to suppress an increase in temperature of the temperature detection means. As a result, the temperature detecting means can measure the temperature of the fixing means with high accuracy,
Further, it is possible to suppress deterioration of the temperature detecting means.

(14) The invention of claim 14 is characterized in that the high heat conduction resistance portion is formed by using a heat insulating material for the main body of the light guiding means. The fixing device is the main point.

In the present invention, since the main body of the light guiding means is made of a heat insulating material, the effect of suppressing heat conduction from the fixing means to the temperature detecting means via the light guiding means is further enhanced. As a result, the temperature detection unit can measure the temperature of the fixing unit with higher accuracy, and further suppress deterioration of the temperature detection unit.

(15) The invention according to claim 15 is characterized in that the high thermal conductive resistance portion is provided in a casing of the temperature detecting means. The device is the gist. The present invention exemplifies the position of the high thermal conductive resistance portion. By providing the high-heat-conducting resistance part in the housing of the temperature detecting means, for example, even when the temperature around the light guiding means or the housing becomes high, heat conduction to the temperature detecting means housed inside the housing is achieved. Can be suppressed, and the temperature rise of the temperature detection means can be suppressed. As a result, the temperature detecting unit can measure the temperature of the fixing unit with high accuracy, and the deterioration of the temperature detecting unit can be suppressed.

As a case equipped with a high heat conduction resistance part,
For example, a material with low overall thermal conductivity (for example, heat-resistant resin)
And a case in which only a portion close to the light guide means is made of a material having a low thermal conductivity. (16) The invention according to claim 16 is characterized in that the fixing device according to any one of claims 1 to 15 is provided with a heat radiating means for removing heat from the light guiding means and / or the temperature detecting means. And

Since the fixing device of the present invention is provided with the heat radiation means, the heat transmitted to the light guide means, the temperature detection means, or both of them can be efficiently removed. As a result, the temperature rise of the temperature detecting means can be suppressed, and the temperature of the fixing means can be measured with high accuracy. Further, it is possible to suppress deterioration of the temperature detecting means.

(17) The invention of claim 17 is characterized in that the heat radiating means is in contact with the light guiding means and / or the temperature detecting means, and is provided with a heat radiating fin.
The fixing device described in No. 6 is the gist. The heat radiating means in the present invention includes the heat radiating fins, so that the heat transmitted to the light guiding means, the temperature detecting means, or both of them can be efficiently released. Therefore, the heat radiating means in the present invention is more effective in removing heat from the temperature detecting means and the light guiding means.

As a result, in the present invention, the temperature rise of the temperature detecting means can be further suppressed, and the temperature of the fixing means can be measured with higher accuracy. Further, the deterioration of the temperature detecting means can be further suppressed. (18) In the invention of claim 18, the heat dissipation means is in contact with the light guide means and / or the temperature detection means, and is in contact with another member having a lower temperature than the light guide means and / or the temperature detection means. The fixing device according to claim 16 is characterized in that.

The heat radiating means in the present invention includes a light guiding means and
Since it is in contact with the temperature detecting means, or both of them, and further in contact with another member having a temperature lower than them, the effect of removing the heat transmitted to the light guiding means, the temperature detecting means, or both of them is further enhanced. high. Therefore, in the present invention,
The temperature rise of the temperature detecting means can be further suppressed, and the temperature of the fixing means can be measured with higher accuracy. Further, the deterioration of the temperature detecting means can be further suppressed.

(19) In the invention of claim 19, the light guide means is fixed to a support member for supporting the fixing means. The device is the gist. In the present invention, the light guide means,
Since the fixing member is fixed to the supporting member that supports the fixing unit, the positional relationship between the light guide unit and the fixing unit is always kept constant.
Therefore, in each of the fixing devices, the temperature detecting means can always detect infrared rays in a certain proportion of the area of the surface of the fixing means.

As a result, in any fixing device, the temperature detecting means can always accurately measure the surface temperature of the fixing means. (20) The invention according to claim 20 is characterized in that the light guide means is positioned with reference to a supporting member for supporting the fixing means. Is the gist.

In the present invention, since the light guide means is positioned with reference to the support member that supports the fixing means, the positional relationship between the light guide means and the fixing means is always kept constant. Therefore, in each of the fixing devices, the temperature detecting means can always detect infrared rays in a certain proportion of the area of the surface of the fixing means.

As a result, in any fixing device, the temperature detecting means can always accurately measure the surface temperature of the fixing means. (21) The invention according to claim 21 provides the fixing device according to claim 19 or 20, characterized in that the temperature detecting means is separable from the light guiding means.

In the present invention, since the temperature detecting means can be separated from the light guiding means, for example, only the temperature detecting means can be removed while the light guiding means remains attached to the fixing device. Therefore, according to the present invention, the temperature detecting means can be easily maintained and the light guide means does not need to be removed, so that the positional relationship between the light guide means and the fixing means does not change. Therefore, the temperature detecting means always detects the infrared rays in a region of a fixed ratio with respect to the surface of the fixing means, so that the temperature detecting means can always accurately measure the surface temperature of the fixing means.

(22) The invention according to claim 22 provides the fixing device according to claim 21, characterized in that the temperature detecting means is attached to the accommodating means. In the present invention, since the temperature detecting means is attached to the accommodating means, it can be removed from the fixing device together with the accommodating means, or only the temperature detecting means can be removed.

(23) The invention according to claim 23 is summarized as the fixing device according to any one of claims 1 to 22, characterized in that the temperature detecting means is a thermopile type infrared sensor. In the present invention, since the temperature detecting means is a thermopile type infrared sensor, the surface temperature of the fixing means can be accurately measured even if the temperature detecting means is arranged at a position distant from the fixing means.

(24) The invention according to claim 24 is summarized as the fixing device according to claim 23, characterized in that the casing of the thermopile type infrared sensor is constituted by a heat insulating member. In the present invention, since the housing of the thermopile infrared sensor is a heat insulating member, it is possible to suppress heat conduction from the periphery of the light guide means and the housing to the thermopile infrared sensor.

As a result, in the present invention, the temperature rise of the thermopile type infrared sensor can be suppressed,
The temperature of the fixing unit can be measured with high accuracy. Further, deterioration of the thermopile type infrared sensor can be suppressed. (25) The invention of claim 25 is summarized as the fixing device according to any one of claims 1 to 24, characterized in that the fixing means is a roller.

In the present invention, since the fixing means is a roller, the medium to be fixed is pressed and fixed on the fixing medium. (26) The invention according to claim 26 is summarized as an image forming apparatus including the fixing device according to any one of claims 1 to 25.

The image forming apparatus of the present invention comprises:
The effect similar to that of the fixing device described in No. 25 is exhibited.

[0049]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example (embodiment) of an embodiment of a fixing device and an image forming apparatus of the present invention will be described. Here, a laser printer will be described as an image forming apparatus. First Embodiment a) First, the configuration of the laser printer of the first embodiment will be described with reference to FIG. Incidentally, FIG. 1 is a side sectional view of a main part of the laser printer.

The laser printer 1 includes a body casing 3
A feeder unit 7 for feeding a sheet 5 as a fixing medium, an image forming unit 9 for forming a predetermined image on the fed sheet 5, and the like are provided therein. The feeder section 7 is provided at the bottom of the main body casing 3.
Paper tray 11 that is detachably attached, and paper tray 1
1, a paper pressing plate 13, a paper feeding roller 15 and a paper feeding pad 17 provided above one end of the paper feeding tray 11, and a downstream side of the paper feeding roller 15 in the conveying direction of the paper 5 ( Hereinafter, the upstream side or the downstream side of the sheet 5 in the transport direction may be simply referred to as the upstream side or the downstream side.), And the transport roller 1.
A registration roller 23 is provided on the downstream side of the sheet 5 in the conveying direction with respect to 9 and 21.

The sheet pressing plate 13 is capable of stacking the sheets 5 in a stacked manner, and is swingably supported at the end portion far from the sheet feeding roller 15, so that the near end portion is vertically moved. It is movable in any direction, and is biased upward from the back side by a spring (not shown). Therefore, as the stacking amount of the sheets 5 increases, the sheet pressing plate 13 swings downward against the biasing force of the spring with the end portion farther from the sheet feeding roller 15 as a fulcrum. The paper feed roller 15 and the paper feed pad 17 are arranged to face each other, and the paper feed pad 17 is pressed toward the paper feed roller 15 by a spring 25 provided on the back side of the paper feed pad 17. .

The image forming section 9 includes a scanner unit 27, a process cartridge 29, a transfer roller 31, a heat fixing device 33 and the like. The scanner unit 27 is provided in the upper part of the main body casing 3, and has a laser emitting portion (not shown) and a polygon mirror 3 that is driven to rotate.
5, the lenses 37 and 39, the reflecting mirror 41, and the like. The laser beam based on the predetermined image data emitted from the laser emitting unit passes or is reflected by the polygon mirror 35, the lens 37, the reflecting mirror 41, and the lens 39 in this order, as shown by the chain line, and the process cartridge 29 described later is used. The surface of the photosensitive drum 45 is irradiated by high speed scanning.

The process cartridge 29 is arranged below the scanner unit 27 and is detachably attached to the main body casing 3. The process cartridge 29 includes the photosensitive drum 45, and also includes a scorotron charger, a developing roller, a toner accommodating portion, and the like, which are not shown.

The toner accommodating portion is filled with a positively chargeable non-magnetic single-component polymerized toner as a developer which is a medium to be fixed, and the toner is carried on the developing roller as a thin layer having a constant thickness. To be done. On the other hand, the photosensitive drum 45 is rotatably arranged so as to face the developing roller, the drum body is grounded, and the surface thereof is formed of a positively chargeable photosensitive layer made of polycarbonate or the like. .

The transfer roller 31 is arranged below the photosensitive drum 45 so as to face the photosensitive drum 45 while being rotatably supported on the main body casing 3 side. The transfer roller 31 has a metal roller shaft covered with a roller made of a conductive rubber material, and a predetermined transfer bias is applied to the photosensitive drum 45.

The heat fixing device 33 is arranged on the downstream side of the process cartridge 29, and is opposed to the heating roller 47 as a fixing means and the heating roller 47 with the conveyance path of the sheet 5 interposed therebetween. A pressing roller 49 that presses the heating roller 47, a heating roller 47 and a pressing roller 49 that cover the pressing roller 49 from above, and a conveying roller 5 that is provided downstream of the heating roller 47 and the pressing roller 49.
3, and a temperature measuring unit 55 for measuring the surface temperature of the heating roller 47.

The heating roller 47 comprises a cylindrical roller body 57 made of a metal tube such as aluminum, and a halogen lamp 59. The halogen lamp 59 is provided in the roller main body 57 along the axial direction, and is configured to generate heat when power is supplied from a power source (not shown), thereby heating the roller main body 57.

The heating roller 47 and the pressing roller 4
9 is rotatably supported by a pair of roller support members 61 described later. The pressing roller 49 has a metal roller shaft covered with an elastic roller, and presses the heating roller 47 with a predetermined pressure.

A paper discharge roller 62 is provided on the downstream side of the heat fixing device 33. b) Next, the configuration of the temperature measurement unit 55 will be described in more detail with reference to FIGS. In addition, in FIG. 2, the temperature measuring unit 55 and its peripheral portion are viewed from the front side (right side in FIG. 1).
3 is a cross-sectional view as seen from FIG. 3, and FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. In addition, FIG.
5 is a sectional view of FIG.

The temperature measuring unit 55 is arranged above the heating roller 47, as shown in FIGS.
The temperature measuring unit 55 has a temperature detecting portion 65 for accommodating a thermopile element 75 (temperature detecting means) described later, and a conduit 67 vertically attached to a temperature measuring unit attaching hole 63 provided at the center of the upper surface of the fixing device case 51. (Light guide unit), and a heat insulating member 69 arranged between the temperature detecting unit 65 and the conduit 67.

As shown in FIG. 4, the temperature detecting section 65 has a cylindrical can case 73 (a casing of a thermopile type infrared sensor) in which an infrared entrance 71 is formed, and an inner upper surface of the can case 73. It is composed of the attached thermopile element 75 (temperature detection means).

The thermopile element 75 is a non-contact type infrared sensor for detecting the temperature by detecting infrared rays radiated from the surface of the heating roller 47 in a non-contact state, and more specifically, It is a thermoelectromotive force type thermopile type infrared sensor.

The thermopile element 75 has a substantially rectangular plate shape and is arranged in the can case 73 so as to face the infrared entrance 71, and its position is outside the fuser case 51 ( 2 and 3, it is above the fuser case 51).

The conduit 67 has a hollow cylindrical shape, and its inner peripheral surface is formed as a reflecting surface 77 made of a metal that reflects infrared rays. As the metal forming the reflecting surface 77, aluminum having a reflectance of 80% or more for infrared rays,
A metal such as silver or gold is preferable, and gold having a high infrared reflectance (infrared reflectance of about 98%) is particularly preferable. Further, the main body of the conduit 67 (the portion other than the reflection surface 77) may be formed of the above metal or other material.

The lower portion of the temperature detecting portion 65 is fitted into the opening portion at the upper end of the conduit 67 via the heat insulating member 69, and the hollow opening portion 79 which is the opening portion at the lower end is the surface of the heating roller 47. Is facing. The heat insulating member 69 is made of polyimide, which is a heat resistant resin having a thermal conductivity of 0.2 W / mK, and as shown in FIG. 5, the inner cylindrical portion 81, which is a cylindrical member, and the outer side of the inner cylindrical portion 81. And an outer cylindrical portion 83 which is a cylindrical member arranged concentrically with each other, and a connecting portion 85 which connects the inner cylindrical portion 81 and the outer cylindrical portion 83 at four locations.

The heat insulating member 69 has an inner cylindrical portion 81.
The lower portion of the can case 73 of the temperature detecting portion 65 is housed inside the pipe, and the conduit 6
It is in contact with the upper part of the inner peripheral surface of 7. c) Next, the operation of the laser printer 1 will be described.

In the paper feeding tray 11 of the feeder unit 7, the uppermost paper 5 on the paper pressing plate 13 is pressed from the back side of the paper pressing plate 13 toward the paper feeding roller 15 by a spring (not shown), and the paper is fed. After the paper roller 15 is rotated, it is sandwiched between the paper feed roller 15 and the paper feed pad 17 and then fed one by one. The fed sheet 5 is sent to the registration roller 23 by the transport rollers 19 and 21. The registration roller 23 is composed of a pair of rollers, and is configured to send the sheet 5 to an image forming position after a predetermined registration. This image forming position is a transfer position where the toner image on the photosensitive drum 45 is transferred onto the sheet 5. In the case of the present embodiment, the photosensitive drum 45 and the transfer roller 3 are arranged.
This is the contact position with 1.

The surface of the photosensitive drum 45 of the image forming section 9 is uniformly positively charged by the scorotron type charger as the photosensitive drum 45 rotates, and then the high-speed scanning of the laser beam from the scanner unit 27 is performed. Exposed
An electrostatic latent image is formed on the surface of the photosensitive drum 45 when the electrostatic latent image based on the image data is formed, and thereafter, the toner carried on the developing roller and positively charged is formed on the surface of the photosensitive drum 45 when facing the developing roller. That is, on the surface of the photosensitive drum 45 which is uniformly positively charged, it is supplied to a portion which is exposed by a laser beam and has a reduced potential, and is selectively carried to form a visible image. Reversal development is achieved.

The visible image composed of the toner image carried on the photosensitive drum 45 is transferred onto the paper 5 while the paper 5 delivered as described above passes between the photosensitive drum 45 and the transfer roller 31. It The sheet 5 on which the visible image is transferred is conveyed to the thermal fixing device 33 described below.

In the heat fixing device 33, the toner image transferred onto the paper 5 is heat-fixed while the paper 5 passes between the heating roller 47 and the pressing roller 49. The surface temperature of the heating roller 47 is constantly measured by the temperature measuring unit 55. That is, the infrared rays radiated from the surface of the heating roller 47 are guided to the infrared entrance 71 of the temperature measuring section 65 while being reflected by the reflecting surface 77 on the inner surface of the conduit 67, and detected by the thermopile element 75 of the temperature measuring section 65. It Then, the output of the halogen lamp 59 of the heating roller 47 is adjusted based on the detected temperature, and the surface temperature of the roller body 57 is controlled to be constant.

The sheet 5 fixed by the heat fixing device 33 is
Then, the sheet is discharged by the transport roller 53 provided on the downstream side of the heat fixing device 33 and the sheet discharge roller 62 disposed on the downstream side of the transport roller 53. d) Next, effects of the fixing device and the image forming apparatus according to the first embodiment will be described.

In the first embodiment, since the thermopile element 75 of the temperature detecting portion 65 is located outside the fixing device case 51, even when the temperature inside the fixing device case 51 rises due to the heat generated by the heating roller 47. The temperature rise of the thermopile element 75 is small. Therefore, accurate temperature detection can be performed, and deterioration of the thermopile element 75 can be suppressed.

In the first embodiment, the reflecting surface 77 having a high reflectance is used.
Therefore, since the conduit 67 for guiding infrared rays to the temperature detecting section 65 is provided, the amount of infrared rays reaching the temperature detecting section 65 does not decrease even if the heating roller 47 and the temperature detecting section 65 are separated from each other. Therefore, infrared rays with a sufficient amount of light are introduced into the temperature detecting section 65, and accurate temperature detection can be performed.

Further, in the temperature detecting portion 65, the length of the conduit 67 and the size of the opening are set by the conduit 67 so that only the infrared rays radiated from the surface of the heating roller 47 are incident on the temperature detecting part 65. A temperature detection error will not occur due to the influence of infrared rays radiated from a portion other than the surface of the roller 47.

In the first embodiment, the thermal conductivity between the can case 73 of the temperature detector 65 and the conduit 67 is 10 W /
Since the heat insulating member 69 of mK or less is provided, heat conduction from the conduit 67 to the can case 73 is unlikely to occur, and the temperature rise of the thermopile element 75 attached to the can case 73 is unlikely to occur.

As a result, the temperature measurement by the thermopile element 75 is highly accurate. In addition, the thermopile element 7
5 can be suppressed. Also, the heat insulating member 69
In, the inner cylindrical portion 81 and the outer cylindrical portion 83 are connected only by the connecting portion 85. That is, the conduit 67
In the heat conducting path from the heat insulating member 69 to the can case 73, the cross-sectional area of the connecting portion 85 is smaller than that of the inner cylindrical portion 81 and the outer cylindrical portion 83 in the plane perpendicular to the heat conducting direction. ing. Therefore, heat conduction from the conduit 67 to the can case 73 is less likely to occur, and the temperature rise of the thermopile element 75 is further suppressed. As a result, the temperature measurement by the thermopile element 75 becomes more accurate, and the deterioration of the thermopile element is further suppressed. Second Embodiment a) The configuration of the laser printer 1 according to the second embodiment will be described with reference to FIGS. 6 and 7.

FIG. 6 is a sectional view of the temperature measuring unit 55 and its peripheral portion as seen from the front side (right side in FIG. 1), and FIG. 7 is a sectional view taken along the line AA in FIG. is there. The configuration of the laser printer 1 according to the second embodiment is basically the same as that of the laser printer 1 according to the first embodiment, and the description of the similar portions will be omitted.

In the second embodiment, a pair of left and right roller supporting members 61 that pivotally support the heating roller 47 and the pressing roller 49.
Is a conduit support member 87 which is a plate-like member arranged horizontally.
Are connected by. And this conduit support member 87
A conduit 67 is fitted in a conduit mounting hole 89 provided at the center of the.

Further, the temperature detecting portion 65 is used in the fixing device case 5.
It is attached to the first temperature measurement unit attachment hole 63. A heat insulating member 69 is provided between the temperature detector 65 and the conduit 67, as in the first embodiment.

B) Next, the laser printer 1 according to the second embodiment.
The effect produced by will be described. In the laser printer 1 according to the second embodiment, the conduit 67 is attached to the roller support member 61 that supports the heating roller 47 via the conduit support member 87, so that the positional relationship of the conduit 67 with respect to the heating roller 47 is always maintained. Is kept constant. Therefore, in the thermal fixing device 33, the temperature detection unit 6
5 can always detect infrared rays in a region of a constant ratio with respect to the surface of the heating roller 47.

As a result, the temperature detector 65 can always accurately measure the surface temperature of the heating roller 47. In the laser printer 1 according to the second embodiment, the conduit 67 is attached to the conduit support member 87, and the temperature detecting unit 65 is attached to the housing. Therefore, with the conduit 67 still attached to the conduit support member 87, the temperature detector 65 is removed together with the fixing device case 51, and the temperature detector 6 is removed.
Only 5 can be removed.

As a result, the temperature detector 65 can be detached for easy maintenance, and at the same time,
Since the conduit 67 does not need to be removed, the positional relationship between the conduit 67 and the heating roller 47 does not change. That is, the laser printer 1 according to the second embodiment can achieve both excellent maintainability and accurate temperature detection. (Third Embodiment) A laser printer according to the third embodiment will be described.

A) First, the laser printer 1 of the third embodiment
The configuration will be described with reference to FIGS. 8 and 9. This Figure 8
FIG. 9 is a cross-sectional view of the temperature measuring unit 55 and its peripheral portion viewed from the front side (right side in FIG. 1), and FIG. 9 is a cross-sectional view taken along the line AA in FIG. 8.

The configuration of the laser printer 1 of the third embodiment is basically the same as that of the laser printer 1 of the second embodiment. Therefore, the description of the same parts as those in the second embodiment will be omitted. In the laser printer 1 according to the third embodiment, in the temperature measuring unit 55, the temperature detecting unit 65 and the conduit 6 are provided.
7, there is no heat insulating member 69, and that portion is a void 91.
Has become. That is, the temperature detecting portion 65 and the conduit 67 are separated by the air.

B) Next, the laser printer 1 according to the third embodiment.
The effect produced by will be described. In the third embodiment, since the void 91 made of air having a low thermal conductivity is formed between the can case 73 of the temperature detection unit 65 and the conduit 67,
The heat conduction from the conduit 67 to the can case 73 hardly occurs, and the temperature rise of the thermopile element 75 attached to the can case 73 hardly occurs.

Therefore, the temperature measurement by the thermopile element 75 is highly accurate. In addition, the thermopile element 7
5 can be suppressed. Fourth Embodiment a) The configuration of the laser printer 1 according to the fourth embodiment will be described with reference to FIG. FIG. 10 is a cross-sectional view of the temperature measuring unit 55 and its peripheral portion viewed from the front side (right side in FIG. 1).

Since the configuration of the laser printer 1 of the fourth embodiment is basically the same as that of the laser printer 1 of the first embodiment, the description of the similar parts will be omitted. In the laser printer 1 of the fourth embodiment, the conduit 67 includes the tubular upper metal portion 93 and the intermediate resin portion 95 (high heat conduction resistance portion).
And the lower metal portion 97 are joined in the axial direction. A reflecting surface 77 is formed on the inner surface of the conduit 67 as in the first embodiment.

The intermediate resin portion 95 has a thermal conductivity of 0.2.
It is made of a heat resistant resin of W / mK and has a length of 1 mm in the vertical direction (vertical direction in FIG. 10). b) Next, effects of the laser printer 1 according to the fourth embodiment will be described. In the laser printer 1 of the fourth embodiment, an intermediate resin portion 95 made of a material having a thermal conductivity of 10 W / mK or less and having a length of 0.1 μm or more is provided in the central portion of the conduit 67. Therefore, heat conduction is less likely to occur in the path from the heating roller 47 to the temperature detection unit 65 via the conduit 67, and the temperature rise of the thermopile element 75 of the temperature detection unit 65 is suppressed. As a result, the temperature measurement by the thermopile element 75 is highly accurate, and deterioration of the thermopile element 75 can be suppressed. (Fifth Embodiment) a) The configuration of the laser printer 1 of the fifth embodiment is basically the same as the configuration of the laser printer 1 of the first embodiment.

However, in the laser printer 1 of the fifth embodiment, the main body of the conduit 67 is made of a heat resistant resin having a thermal conductivity of 0.2 W / mK. The reflecting surface 77 formed on the inner surface of the conduit 67 is the same as that in the first embodiment. That is, in the fifth embodiment, the main body of the conduit 67 is the high heat conduction resistance portion.

B) In the laser printer 1 of the fifth embodiment,
Since the main body of the conduit 67 is made of a heat-resistant resin having a thermal conductivity of 10 W / mK or less, heat conduction does not easily occur in the path from the heating roller 47 through the conduit 67 to the temperature detection unit 65, and the temperature of the thermopile element 75 rises. It can be suppressed. As a result, the temperature measurement by the thermopile element 75 is highly accurate, and deterioration of the thermopile element 75 can be suppressed. (Sixth Embodiment) a) The configuration of the laser printer 1 according to the sixth embodiment will be described with reference to FIGS. 11 to 15. 11 is a cross-sectional view showing the vicinity of the temperature measuring unit 55, and FIGS. 12 to 15 are perspective views showing the configuration of a radiator 99 described later.

Since the configuration of the laser printer 1 of the sixth embodiment is basically the same as that of the laser printer 1 of the first embodiment, the description of the similar parts will be omitted. In the laser printer 1 of the sixth embodiment, as shown in FIGS. 11 and 12, a cylindrical radiator 99 is covered on the upper portion of the can case 73 of the temperature detector 65.

As shown in FIG. 13, the radiator 99 may be composed of a cylindrical radiator body 101 and vertical fins 103 provided vertically on the side surface of the radiator body 101. Of course, as shown in FIG. 14, it may be composed of a cylindrical radiator main body 101 and a ring-shaped horizontal fin 105 horizontally provided on the side surface of the radiator main body 101.

Further, as the radiator 99, as shown in FIG. 15, a plate-like one mounted on the upper surface of the can case 73 of the temperature detecting portion 65 may be used. This plate-shaped radiator 99 is
A terminal extraction hole 107 is provided at the center thereof. Therefore, the temperature detection unit 65 including the terminal 109 protruding upward is provided.
When using, as shown in FIG.
The terminal 109 taken out from 07 can be connected to the substrate 111. The substrate 111 may be equipped with a circuit for amplifying an output signal output from the thermopile element 75, and an electronic component for adjusting the output of the halogen lamp 59 included in the heating roller 47 based on the output signal. it can.

The radiator 99 is attached to, for example, the can case 73 and is brought into contact with another member (for example, the main body casing 3) constituting the laser printer 1 so that the heat of the can case 73 is transferred to the other member. You may let it escape. b) Next, effects of the laser printer 1 according to the sixth embodiment will be described.

In the laser printer 1 of the sixth embodiment, since the radiator 99 is attached to the can case 73,
The can case 73 has a high heat dissipation effect, and the temperature of the thermopile element 75 attached to the can case 73 is unlikely to rise. Therefore, the temperature measurement by the thermopile element 75 is highly accurate, and deterioration of the thermopile element 75 can be suppressed.

Especially, the horizontal fins 103 and the vertical fins 105
In the radiator 99 provided with, the heat dissipation effect is further enhanced, and the temperature rise of the thermopile element 75 can be further suppressed. (Embodiment 7) The configuration of the laser printer 1 according to Embodiment 7 is as follows.
Basically, it is almost the same as the laser printer 1 of the first embodiment.

However, in the laser printer 1 of the seventh embodiment, the can case 73 of the temperature detecting portion 65 is made of a heat resistant resin having a high heat conduction resistance (heat conductivity is 0.2 W / mK). That is, in the seventh embodiment, the can case 73 is used.
Is a conduit 67 and the thermopile element 7 as a high heat conduction resistance part.
5, the heat conduction from the conduit 67 to the thermopile element 75 is suppressed even when the temperature of the conduit 67 rises.

Therefore, the temperature rise of the thermopile element 75 is suppressed, and the accuracy of temperature measurement by the thermopile element 75 is high. Further, deterioration of the thermopile element 75 can be suppressed. It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the scope of the present invention.

In the first to seventh embodiments, in the heat fixing device 33, the heating roller 4 is provided by the thermopile element 75.
Although the temperature of the surface of No. 7 is detected, for example, the surface of the heating roller 47 and the surface of the pressing roller 49 having a high temperature correlation may be detected.

Although the heating roller 47 and the pressing roller 49 are used as the fixing means in the first to seventh embodiments, a belt-shaped fixing means may be used in the present invention.
For example, it may be applied to any of a belt-shaped heating member and a roller-shaped pressing member, a roller-shaped heating member and a belt-shaped pressing member, or a belt-shaped heating member and a belt-shaped pressing member. .

In the first to seventh embodiments, the cross-sectional shape of the hollow tubular conduit 67 in the direction orthogonal to the axial direction of the conduit 67 is not particularly limited. For example, a polygonal shape such as a circle or a quadrangle. And the conduit 67
The cross-sectional shape along the axial direction of may be tapered.

In the first to seventh embodiments, the heat fixing device of the laser printer 1 is described as an example of the fixing device. However, the fixing device is not limited to this. It may be a laminator for thermally fixing the fixing medium.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a laser printer of an embodiment.

FIG. 2 is an explanatory diagram showing a configuration of a temperature measurement unit according to an embodiment.

FIG. 3 is an explanatory diagram showing a configuration of a temperature measuring unit according to an embodiment.

FIG. 4 is an explanatory diagram showing a configuration of a temperature sensor in the example.

FIG. 5 is an explanatory diagram showing a configuration of a heat insulating member in the example.

FIG. 6 is an explanatory diagram showing a configuration of a temperature measurement unit according to an embodiment.

FIG. 7 is an explanatory diagram showing a configuration of a temperature measurement unit according to an embodiment.

FIG. 8 is an explanatory diagram showing a configuration of a temperature measurement unit according to an embodiment.

FIG. 9 is an explanatory diagram showing a configuration of a temperature measurement unit according to an embodiment.

FIG. 10 is an explanatory diagram showing a configuration of a temperature measurement unit according to an embodiment.

FIG. 11 is an explanatory diagram showing a configuration of a temperature measurement unit according to an embodiment.

FIG. 12 is an explanatory diagram showing a configuration of a radiator in the example.

FIG. 13 is an explanatory diagram showing a configuration of a radiator in the example.

FIG. 14 is an explanatory diagram showing a configuration of a radiator in the example.

FIG. 15 is an explanatory diagram showing a configuration of a radiator according to the embodiment.

FIG. 16 is an explanatory diagram showing configurations of a temperature measuring unit and a radiator in the example.

[Explanation of symbols]

1 ... Laser printer 3 ... Main body casing 9 ... Image forming unit 33 ... Heat fixing device 45 ... Photosensitive drum 47 ... Heating roller 49 ... Pressing roller 51: fuser case 55 ... Temperature measurement unit 57: roller body 59 ... Halogen lamp 61 ... Roller support member 65 ... Temperature sensor 67 ... conduit 69 ... Insulation member 73 ... Can case 75 ... Thermopile element 77 ... Reflective surface 87 ... Conduit support member 91 ... Empty wall 95 ... Intermediate resin part 99 ... Radiator

Claims (26)

[Claims] 1. A fixing unit for heating and fixing a medium to be fixed on a fixing medium, a containing unit for containing the fixing unit, and an infrared ray radiated from a surface of the fixing unit.
A fixing device comprising: a temperature detecting unit that measures a surface temperature of the fixing unit; and a light guiding unit that guides infrared rays emitted by the fixing unit to the temperature detecting unit. The fixing device is characterized in that the light guide means includes a hollow portion that is a path of infrared rays, and a reflecting surface that faces the hollow portion so as to reflect the infrared rays. 2. A high heat conduction resistance portion for inhibiting the heat conduction in a heat conduction path from the heat generated by the fixing means to the temperature detecting means via the light guiding means. The fixing device according to claim 1. 3. A fixing unit that heats and fixes a medium to be fixed on a fixing medium; and an infrared ray radiated from the surface of the fixing unit.
In a fixing device including a temperature detecting unit that measures a surface temperature of the fixing unit and a light guiding unit that guides infrared rays emitted by the fixing unit to the temperature detecting unit, heat generated by the fixing unit is guided by the light guiding unit. A fixing device characterized by comprising a high heat conduction resistance portion which inhibits the heat conduction in a heat conduction path from a means to the temperature detecting means. 4. The fixing device according to claim 3, further comprising accommodating means for accommodating the fixing means. 5. The fixing device according to claim 2, wherein the high thermal conductive resistance portion is a portion made of a heat insulating material. 6. The heat insulating material has a thermal conductivity of 10 W / m.
The fixing device according to claim 5, wherein the fixing device is made of a material of K or less. 7. The fixing device according to claim 5, wherein the heat insulating material is a heat resistant resin. 8. The fixing device according to claim 5, wherein the portion made of the heat insulating material has a length of 0.1 mm or more along the heat conduction path. 9. The fixing device according to claim 2, wherein the high heat conduction resistance portion is a portion of the heat conduction path separated by air. 10. The portion separated by the air is
The fixing device according to claim 9, wherein the fixing device has a length of 0.1 mm or more along the heat conduction path. 11. The high heat conduction resistance portion is a cross-sectional area of a plane perpendicular to a heat conduction direction in the heat conduction path,
The fixing device according to any one of claims 2 to 4, wherein the fixing device is a portion that is smaller than a cross-sectional area in front and rear portions thereof. 12. The fixing device according to claim 2, wherein the high thermal conductive resistance portion is provided between the light guide unit and the temperature detection unit. 13. The high heat conductive resistance portion is provided in the light guide means, according to any one of claims 2 to 11.
The fixing device according to any one of 1. 14. The fixing device according to claim 13, wherein the high thermal conductive resistance portion is formed by using a heat insulating material for the main body of the light guide unit. 15. The fixing device according to claim 2, wherein the high thermal conductive resistance portion is provided in a casing of the temperature detecting means. 16. The fixing device according to claim 1, further comprising a heat dissipation unit that removes heat from the light guide unit and / or the temperature detection unit. 17. The heat radiating means is the light guiding means and / or
Alternatively, the fixing device according to claim 16, further comprising a heat radiation fin in contact with the temperature detecting means. 18. The heat radiating means is the light guiding means and / or
17. The fixing device according to claim 16, wherein the fixing device is in contact with the temperature detecting unit and is in contact with the light guide unit and / or another member having a temperature lower than that of the temperature detecting unit. 19. The fixing device according to claim 1, wherein the light guide unit is fixed to a support member that supports the fixing unit. 20. The fixing device according to claim 1, wherein the light guide unit is positioned with reference to a supporting member that supports the fixing unit. 21. The fixing device according to claim 19, wherein the temperature detecting unit is separable from the light guiding unit. 22. The fixing device according to claim 21, wherein the temperature detecting means is attached to the housing means. 23. The temperature detecting means is a thermopile type infrared sensor, wherein the temperature detecting means is a thermopile type infrared sensor.
2. The fixing device according to any one of 2. 24. The fixing device according to claim 23, wherein a housing of the thermopile type infrared sensor is composed of a heat insulating member. 25. The fixing device according to claim 1, wherein the fixing unit is a roller. 26. An image forming apparatus comprising the fixing device according to any one of claims 1 to 25.