JPH0726850U - Fixing device - Google Patents

Abstract

(57) [Summary] [Object] To provide a fixing device capable of downsizing a heating roller, having excellent thermal efficiency, and enabling accurate temperature control. [Structure] A part 4a of the glass of the heat generating lamp 4 is formed into a convex lens shape, and light from the lamp is condensed. The condensing position F is a nip portion 3 between the heating roller 1 and the pressure roller 2,
Intermediate point on the circumference of the mounting position of the temperature detecting means 6 ± 1
It is desirable to be within the range of 0%.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat fixing device used in an image forming apparatus such as a copying machine or a laser printer, and more particularly to a fixing device having excellent thermal efficiency and capable of accurate temperature control.

[0002]

[Prior art]

 Conventionally, in image forming apparatuses such as copying machines and laser printers, a heat roller type fixing device for fixing toner to recording paper by heat and pressure is widely used. In this fixing device, a halogen lamp as a heat generating lamp is provided inside the heating roller, but the light and heat from this halogen lamp are emitted in the entire circumferential direction of the lamp and heat the entire heating roller. . For this reason, heat is released into the air from the entire surface of the heating roller, resulting in very poor thermal efficiency.

Further, the heat released into the air raises the temperature inside the image forming apparatus, which makes the electrophotographic process unstable or shortens the life of the photoconductor and the like, and further, the apparatus main body is expensive. It is necessary to use a heat-resistant resin, which causes a cost increase.

As a fixing device for solving such a problem, as shown in FIG. 2, a reflecting member 5 for reflecting and condensing the light from the heat generating lamp 4 is provided, and the reflecting member 5 reflects the light. It has been proposed that the position F for making light is set on the upstream side of the nip portion 3 of the heating roller 1 and the pressure roller 2 in the roller rotation direction and on the downstream side of the temperature detecting means 6 (Japanese Patent Laid-Open No. Hei 10 (1999) -242242). No. 4-212978).

[0005]

[Problems to be solved by the device]

 However, in such a conventional fixing device, since the reflecting member 5 is provided outside the heat-generating lamp 4 separately from the heat-generating lamp 4, the heating roller 1 becomes larger and the mounting member is removed from the reflecting member 5. Since heat is transferred to the fixing device body via the fixing device body and the temperature of the device body rises, there is a problem that an expensive heat resistant resin must be used. 6 is much larger than the distance from the position F to the nip portion 3 of the heating roller 1 and the pressure roller 2, the heating roller surface temperature at the mounting position of the temperature detecting means 6 is greater than that of the nip portion 3. The temperature of the nip portion 3 is controlled to be higher than the set temperature, which causes a problem that an offset occurs.

Therefore, an object of the present invention is to solve the problems of the conventional device, to downsize the heating roller, to prevent the temperature of the fixing device main body from increasing, and An object of the present invention is to provide a fixing device having excellent thermal efficiency and capable of accurate temperature control.

[0007]

[Means for Solving the Problems]

 As a result of various studies to achieve the above-mentioned object, the present inventor has conceived that the glass itself of the heat generating lamp has a convex lens shape, and further, the position where the light is reflected and condensed is set at the nip portion and the temperature. We have found that it is sufficient to set the position approximately in the middle of the mounting position of the detection means, and completed the present invention.

That is, according to the present invention, (1) in a fixing device having a metal rotary heating roller containing a heat generating lamp and a pressure roller rotating in pressure contact with the heating roller, the glass of the heat generating lamp is used. A part of the fixing lens is formed in a convex lens shape to collect the light from the heat generating lamp, and (2) the temperature detecting means for detecting the surface temperature is provided on the heating roller. The light collecting position of the light from the heat generating lamp is upstream of the nip portion between the heating roller and the pressure roller in the roller rotation direction, and is downstream of the mounting position of the temperature detecting means. At the same time, there is provided the fixing device according to (1), wherein the fixing device is within the range of ± 10% on the circumference between the nip portion and the temperature detecting means mounting position.

[0009]

[Action]

 In the fixing device of the present invention, the glass of the heat-generating lamp itself has a convex lens shape to collect the light from the heat-generating lamp. Therefore, in addition to the heat-generating lamp, a conventional heating roller provided with a reflecting member on the outside thereof is used. In comparison, the heating roller can be downsized. Further, since no reflecting member is provided as in the conventional device, there is no heat transfer from the reflecting member, and the temperature rise of the fixing device main body due to this does not occur.

Further, when the light condensing position is within the range of ± 10% of the middle point on the circumference between the nip portion and the temperature detecting means mounting position, the heating roller at the temperature detecting means mounting position is provided. The surface temperature becomes almost the same as that of the nip portion, and as a result, the temperature of the nip portion can be accurately controlled and the occurrence of offset or the like can be prevented.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the fixing device of the present invention. Reference numeral 1 is a metallic rotary heating roller, 2 is a pressure roller which rotates in pressure contact with the heating roller 1, 3 is both rollers 1, 2 It is a nip portion formed by.

A heating lamp (for example, a halogen lamp) 4 is provided inside the heating roller 1, and a part 4 a of the glass of the heating lamp 4 has a convex lens shape. The light from is collected.

The surface temperature of the heating roller 1 is detected by a temperature detecting means 6 such as an infrared sensor or a thermistor, and is controlled to a constant temperature by controlling the heating lamp 4 to be turned on and off by a known on / off control method. Retained.

The curvature of the convex lens formed on the part 4 a of the glass of the heat generating lamp 4 is appropriately set according to the dimensions of the heating roller 1, usage conditions and the like.

Further, in the present invention, the position F where the light of the heat generating lamp 4 is focused is located in the roller rotation direction (arrow A in FIG. 1) rather than the nip portion 3 between the heating roller 1 and the pressure roller 2. It is desirable that it is on the upstream side and downstream of the mounting position of the temperature detecting means 6.

At the position F where the light is focused, the surface temperature of the heating roller 1 is always the maximum temperature in the nip portion 3 depending on the thermal conductivity of the metal used for the heating roller 1, the rotation speed of the heating roller 1, and the like. The optimum position is determined so that the thermal efficiency is improved.

When the light collecting position F is on the upstream side of the mounting position of the temperature detecting means 6, the temperature detecting means 6 detects a temperature higher than that of the nip portion 3, and the nip portion 3 is detected. The temperature is controlled to be lower than the set temperature, so that the fixing property is deteriorated and an offset occurs, which is inappropriate.

Further, it is desirable that the light condensing position F is within a range of ± 10% of the midpoint on the circumference between the nip portion 3 and the mounting position of the temperature detecting means 6. The surface temperature of the heating roller 1 in the section 3 becomes substantially equal to the mounting position of the temperature detecting means 6, and the temperature is accurately controlled to the set temperature, and problems such as offset do not occur.

The heating roller 1 in the fixing device of the present invention preferably has a thickness of 1 mm or less in order to raise the temperature to a predetermined temperature as quickly as possible after condensing at the condensing position F. .

[0020]

[Effect of device]

 According to the present invention, the heating roller can be downsized, and since the temperature of the main body of the apparatus does not rise due to the heat transfer from the reflecting member, it is not necessary to use expensive heat-resistant resin. Since the surface temperature can always be the maximum temperature in the nip part, the thermal efficiency can be improved and the roller surface temperature in the nip part can be accurately controlled, causing troubles such as offset. Can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a fixing device of the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating roller 2 Pressure roller 3 Nip part 4 Heat generating lamp 4a Convex lens glass part 6 Temperature detecting means F Light condensing position

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H05B 3/44 7715-3K

Claims (2)

[Scope of utility model registration request] 1. A fixing device having a metal rotary heating roller containing a heating lamp and a pressure roller rotating in pressure contact with the heating roller, wherein a part of the glass of the heating lamp has a convex lens shape. A fixing device characterized in that light from a heat-generating lamp is condensed. 2. A temperature detecting means for detecting a surface temperature is provided on the heating roller, and a light collecting position of the light from the heat generating lamp is a roller more than a nip portion between the heating roller and the pressure roller. It is on the upstream side in the rotation direction and on the downstream side of the mounting position of the temperature detecting means, and within a range of ± 10% on the circumference between the nip portion and the mounting position of the temperature detecting means. The fixing device according to claim 1, wherein