JP2626564B2 - Thermal fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an electrophotographic printer, and more particularly, to a recording medium on which a toner image has been transferred by applying pressure while heating the recording medium with a heat roller and a pressure roller. The present invention relates to a heat fixing device that performs pressure fixing on a recording medium.

[0002]

2. Description of the Related Art As shown in FIG. 5, a general electrophotographic printer device includes a photosensitive drum 1 rotating in the direction of an arrow P.
01 is charged by the pre-charger 102, and then the exposure unit 103 exposes the surface of the photosensitive drum 101 to form an electrostatic latent image. An image is formed, and thereafter, the recording medium 12 conveyed while being in contact with the photosensitive drum 101 by the conveying roller 107.
0, the transfer unit 105 transfers the toner image. After the transfer, the photosensitive drum 1
01 was removed by the cleaner 106.

Here, in the electrophotographic printer having the above configuration, the toner image at the time when the toner image is transferred onto the recording medium 120 such as paper or a sheet for an overhead projector has powder toner adhered to the surface of the recording medium 120. It just peels off easily. Therefore, a fixing device for fixing a toner image on the recording medium 120 is conventionally provided in an electrophotographic printer device, and one of them is a heat fixing device.

In FIG. 5 and FIG. 6, reference numeral 110 denotes a heat fixing device, which is driven to rotate in conjunction with a photosensitive drum 101 and a conveying roller 107, and is heated by a built-in heater 111a; The heat roller 111 rotates while being pressed against the roller 111.
, A pressure roller 112 that conveys the recording medium 120 therebetween, a bearing 113 of a heat roller 111, a peeling claw 114 that peels off the leading end of the recording medium 120 attached to the heat roller 111, Unloading roller 115 for unloading the recording medium 120 peeled off by
And was provided with.

According to such a configuration, the heat roller 1
The pressure roller 11 and the pressure roller 112 convey the recording medium 120 onto which the toner image has been transferred while heating and pressurizing the toner image, and fix the toner image onto the recording medium 120 by pressure.

Here, in the conventional heat fixing device, the heat roller 111 is provided with a temperature detecting means in order to detect abnormal heating of the heat roller 111 and prevent occurrence of an accident. For example, in Japanese Patent Application Laid-Open No. 4-322285, in order to prevent the adhesion of the molten toner when printing is performed for a long time or when paper jam occurs, a winding-type shielding curtain (between a heat roller and a temperature detecting means) is used. A thermal fixing device provided with a fused toner adhesion preventing means) has been proposed.

The heat fixing device shown in FIG. 7 is designed to reduce the size and cost of an electrophotographic printer.
In the heat fixing device disclosed in Japanese Patent Application Laid-Open No. 4-322285, means for preventing adhesion of molten toner such as a shield curtain is reduced, and a predetermined distance W (0.5 mm to
1 mm) and temperature detecting means (thermostat) 11
6 was arranged. According to the heat fixing device of FIG. 7 having such a configuration, the temperature of the surface of the heat roller 111 can be detected without bringing the temperature detection unit 116 and the heat roller 111 into contact with each other. Can be.

[0008]

However, in the above-described conventional heat fixing device shown in FIG. 7, the temperature detecting means 116 and the heat roller 111 are not in contact with each other, and an air gap (a predetermined interval W) is provided therebetween. Temperature detection means 1
The heat conduction state between the heat roller 111 and the heat roller 111 is deteriorated by the flow of air or the like, and the temperature detected by the temperature detecting means 116 becomes lower than the actual surface temperature of the heat roller 111. For this reason, the conventional heat fixing device shown in FIG. 7 cannot accurately detect the abnormal heating of the heat roller 111, and has a problem that a fire accident occurs when paper jam occurs in the heat fixing device. .

Further, the above-mentioned conventional Japanese Patent Application Laid-Open No. 4-322285.
In the thermal fixing device of No. 1, the temperature detecting means and the heat roller are configured to be in contact with each other, so that such a problem does not occur. There is a problem that the size and cost of the printer cannot be reduced.

[0010] Here, as a means for reducing the adhesion of the molten toner, there is provided a structure in which the temperature detecting means and the heat roller are in contact with each other. Contact may be considered. However, with such a configuration, there is a problem that the overall length L of the heat roller (see FIG. 7) becomes longer, and the heat fixing device becomes larger.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a simple structure, can reduce the number of parts and can downsize a device, and can accurately detect the surface temperature of a heat roller. An object of the present invention is to provide a heat fixing device capable of performing an appropriate protection operation.

[0012]

According to a first aspect of the present invention, there is provided a heat fixing device, wherein a heat is applied to a recording medium onto which a toner image has been transferred by a heat roller and a pressure roller. In a heat fixing device for fixing the toner image on a recording medium , a mounting chamber is formed inside a bearing that supports the heat roller, and in the mounting chamber,
Pressed against the outer peripheral surface of the heat roller by an elastic body
The temperature detecting means is provided.

According to a second aspect of the present invention, in the heat fixing device, the toner image is
Transfer the transferred recording medium to a heat roller and pressure
The toner image is recorded while applying pressure while heating with a heater.
In a heat fixing device for fixing to a recording medium, while providing a heat conductive member that contacts the outer peripheral surface of the heat roller ,
Corresponding to the shape of the heat conducting member into which the heat conducting member is fitted
A concave portion having a shaped as above is formed on the side of the bearing, and the temperature is detected.
The informing means is configured to be attached to the heat conducting member .

According to a third aspect of the present invention , in the heat fixing device,
The part of the member that contacts the outer peripheral surface of the heat roller also has a width.
It is configured to be a heat conduction bearing.
4. The heat fixing device according to item 4, wherein the heat is applied from outside the bearing.
Insert the ring into the end of the roller and remove the heat roller.
The structure is also supported from the inner peripheral side .

[0015]

According to the heat fixing device of the present invention having the above-described structure, the temperature detecting means provided on the bearing of the heat roller includes:
In direct contact with the end of the heat roller, or a heat conducting member,
The surface temperature of the heat roller is detected via a heat conduction shaft or the like. Thus, while ensuring the configuration in which the temperature detection unit and the heat roller are in contact with each other, it is possible to reduce the fusion toner adhesion prevention unit, accurately detect the surface temperature of the heat roller, and reduce the size and simplification of the device. Can be.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the heat fixing device of the present invention will be described below with reference to the drawings. First, a heat fixing device according to a first embodiment of the present invention will be described. FIG. 1 is a perspective view showing the heat fixing device according to the first embodiment. FIG.
(A) is a front view showing a bearing of the present thermal fixing device, and (b) of FIG.
FIG. 2 is a sectional view taken along line AA of FIG. In the present embodiment, the temperature detecting means is embedded in the bearing of the heat roller bearing, and the temperature detecting means is pressed against the heat roller by an elastic body.

In these drawings, reference numeral 10 denotes a heat roller, which has a structure in which a heater 11 is built in an aluminum tube coated with Teflon. Both ends of the heat roller 10 are rotatably attached to a bearing 20 via a heat-resistant resin member 21 and are driven to rotate in conjunction with a photosensitive drum and a transport roller (not shown).

Reference numeral 30 denotes a pressure roller having a cylindrical member coated with silicone rubber. The pressure roller 30 rotates while being pressed against the heat roller 10, and the recording medium 8 is interposed between the pressure roller 30 and the heat roller 10.
The sheet is conveyed in a state sandwiching 0.

Reference numeral 40 denotes a temperature detecting means (thermostat), which is embedded in a mounting chamber 22 formed inside the bearing 20. Further, the temperature detecting means 40 is pressed by a spring (elastic body) 41 so that the temperature detecting surface comes into contact with the surface (outer peripheral surface) of the heat roller 10. The input / output terminal 42 of the temperature detecting means 40 is connected to a power supply circuit of the heater 11 (not shown), and operates when the surface temperature of the heat roller 10 becomes higher than a preset temperature. To stop supplying power.

According to the heat fixing apparatus of the present embodiment having the above-described structure, the temperature detecting means 40 directly contacts the heat roller 10 inside the bearing 20 to detect the surface temperature of the heat roller 10. And a paper jam or heater 1
The heat roller 10
When the surface temperature of the heater becomes higher than the temperature preset in the temperature detecting means 40, the temperature detecting means 40
The power supply to the heat roller 10 is stopped, and abnormal heating of the heat roller 10 is prevented.

Here, in the heat fixing device of the present embodiment, the temperature detecting means 40 is mounted inside the bearing 20, so that the temperature detecting means 40 and the heat roller 10 are brought into direct contact with each other, The surface temperature can be detected, whereby the surface temperature of the heat roller 10 can be accurately detected. Further, the temperature detecting means 4
Since the surface temperature of the heat roller 10 can be detected without toner adhering to the surface of the heat roller 10, the means for preventing fusion toner adhesion in the conventional heat fixing device can be reduced, and the apparatus can be simplified, downsized, and reduced in cost.

In this embodiment, in order to reduce the cost of the apparatus, a thermostat is used for the temperature detecting means 40, and when the surface temperature of the heat roller 10 becomes higher than a preset temperature, the heater 11 is turned on. However, a configuration may be adopted in which a temperature sensor such as a thermistor or a thermocouple is used as the temperature detecting means, and a control unit (not shown) controls the heater 11 based on signals from these temperature sensors. The elastic body that presses the temperature detecting means 40 against the heat roller 10 includes a spring 41.
However, the present invention is not limited to this, and can be changed to another elastic body such as a leaf spring.

Next, a heat fixing device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a partially exploded perspective view showing the heat fixing device according to the second embodiment. In the heat fixing device of the present embodiment, the temperature detecting means is configured to detect the surface temperature of the heat roller via a heat conductive plate (heat conductive member) in contact with the heat roller.

In FIG. 1, reference numeral 50 denotes a heat conducting plate, in which a hole 51 into which the heat roller 10 is inserted is formed. The mounting portion 52 of the temperature detecting means 40 is formed on the heat conducting plate 50, and the temperature detecting surface is formed on the surface (outer periphery) of the heat conducting plate 50.
Temperature detecting means 40 is attached so as to come into contact with ( surface) . A concave portion 23 corresponding to the shape of the heat conductive plate 50 is provided on the outer periphery of the bearing portion on the outer surface of the bearing 20, and the heat conductive plate 50 is fitted into the concave portion 23 so that the heat conductive plate 50 is 20 and integrated. Further, in the present embodiment, a heat-resistant resin ring 60 that is not deteriorated by heat is used as a bearing.
20 into the end of the heat roller 10 from outside ,
The heat roller 10 is supported from the inner peripheral side and attached to the bearing 20.

According to the heat fixing device of this embodiment having the above-described configuration, the heat of the heat roller 10 is
Is transmitted to the temperature detecting means 40 via the
As in the case where the heat roller 10 and the heat roller 10 are directly contacted, accurate temperature detection can be performed.

Next, a heat fixing device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a partially exploded perspective view showing the heat fixing device according to the third embodiment. In the thermal fixing device of the present embodiment, the temperature detecting means 40 is connected to the heat roller 10 via the heat conductive bearing 70 for conducting heat of the heat roller 10 and the heat conductive plate 50 joined to the heat conductive bearing 70. The surface temperature is detected.

According to the heat fixing device of this embodiment having the above-described structure, the heat roller 10 is supported by the heat-conducting bearing 70, so that the heat roller 10
The contact area with the heat roller 10 increases, and the surface temperature of the heat roller 10 can be detected more effectively.

According to the heat fixing device of each embodiment having the above-mentioned configuration, the temperature detecting means 40 and the heat roller 10 can be brought into direct or indirect contact with each other, and therefore, the conventional heat fixing device shown in FIG. An air gap (predetermined interval W) does not occur, and it is possible to prevent a variation in detection temperature and an error from occurring, and to accurately detect the surface temperature of the heat roller 10. In addition, the provision of the temperature detecting means 40 in the bearing 20 can reduce the means for preventing the adhesion of the molten toner in the conventional heat fixing device, thereby achieving simplification, miniaturization and low cost of the equipment.

Further, according to the heat fixing device of each embodiment having the above configuration, the surface temperature of the heat roller 10 can be detected without increasing the total length L of the heat roller 10 (see FIG. 7). The device does not become large.

The heat fixing device of the present invention is not limited to the above embodiment. In the third embodiment, the temperature detecting means 40 is configured to detect the surface temperature of the heat roller 10 via the heat conductive bearing 70 and the heat conductive plate 50. However, the present invention is not limited to this. Means 40
However, a configuration in which the temperature of the heat roller 10 is detected only through the heat conduction bearing 70 may be adopted.

[0031]

As described above, according to the heat fixing apparatus of the present invention, the number of parts can be reduced and the size of the apparatus can be reduced, and the surface temperature of the heat roller can be accurately controlled. Detect and perform appropriate protection operation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a heat fixing device according to a first embodiment of the present invention.

FIG. 2A is a front view showing a bearing of the present thermal fixing device, and FIG. 2B is a sectional view taken along line AA of FIG.

FIG. 3 is a partially exploded perspective view showing a heat fixing device according to a second embodiment of the present invention.

FIG. 4 is a partially exploded perspective view showing a heat fixing device according to a third embodiment of the present invention.

FIG. 5 is an explanatory view showing a conventional general electrophotographic printer.

FIG. 6 is a partial cross-sectional side view showing a heat fixing device according to a conventional example.

FIG. 7 is a perspective view showing a heat fixing device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heat roller 11 Heater 20 Bearing 21 Heat resistant resin member 22 Mounting part 23 Depression 30 Pressure roller 40 Temperature detecting means 41 Spring 42 I / O terminal 50 Heat conduction plate (heat conduction member) 51 Hole 52 Mounting part 60 Heat resistant resin ring 70 Heat conduction Bearing 80 Recording medium

Claims (4)

(57) [Claims] 1. A heat fixing device for applying pressure while heating a recording medium onto which a toner image has been transferred by a heat roller and a pressure roller to fix the toner image on the recording medium, wherein a bearing for supporting the heat roller is provided . Forming a mounting room inside
And, in this mounting room, the outer peripheral surface of the heat roller is elastic.
A heat fixing device characterized in that a temperature detecting means pressed by a body is provided . 2. A recording medium onto which a toner image has been transferred is heated.
Pressure while heating by roller and pressure roller
And a heat fixing device for fixing the toner image on a recording medium.
In location, provided the heat-conducting member in contact with the outer peripheral surface of the heat roller
And the heat conducting member into which the heat conducting member is fitted.
A recess with a shape corresponding to the shape of the bearing is formed on the side of the bearing
And the temperature detecting means is attached to the heat conducting member.
And a heat fixing device. 3. An outer periphery of said heat roller of said heat conducting member.
A heat-conducting bearing with a width in contact with the surface
3. The heat fixing device according to claim 2, wherein: 4. The heat roller from outside the bearing.
Insert a ring into the end and move the heat roller
3. The heat fixing device according to claim 2, wherein the heat fixing device is also supported.