JP3234656B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a radiant heating element such as a halogen heater inside a fixing roller, and transmits radiant heat energy absorbed by the inner surface of the fixing roller to the surface of the fixing roller by heat conduction of the fixing roller itself. A heat generating layer is provided on the surface of a fixing roller having a method of applying this heat energy to a recording material, or a fixing roller having a hollow metal core, and the heat energy from the heat generating layer is applied to the recording material directly or through a release layer. The present invention relates to a fixing device of a method of applying.

[0002]

2. Description of the Related Art This apparatus is an image heating and fixing apparatus in an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, etc., that is, it is heated and melted by an appropriate image forming process means such as electrophotography, electrostatic recording and magnetic recording. Directly or indirectly (transfer) formed on the surface of a recording material (electrofax sheet, electrostatic recording sheet, transfer sheet, printing paper, etc.) using a toner made of resin, etc., unfixed corresponding to the target image Is an apparatus for heat-fixing the toner image as a permanently fixed image on a recording surface carrying the image.

FIG. 7 is a longitudinal sectional view of a specific example of the fixing device. In FIG. 7, the upper fixing roller 1 is a heater in which a heater 2 such as a halogen lamp is placed inside a hollow metal core made of aluminum, iron, or the like, and the heater 2 heats the fixing roller 1. . Reference numeral 101 denotes a release layer for improving the surface properties of the fixing roller 1, and a fluororesin coating or a tube is preferably used. The lower pressure roller 3 is formed by covering the outer periphery of a core metal 304 such as iron or stainless steel with an elastic body 305 having a releasing property such as silicone rubber. The fixing roller 1 and the pressure roller 3 are brought into contact with each other at a predetermined pressure by urging means such as a spring (not shown), and are driven to rotate in the direction of the arrow.

[0006] Reference numeral 6 denotes a temperature-sensitive element such as a thermistor brought into contact with the surface of the fixing roller 1, and detects the surface temperature of the fixing roller 1. The power supply to the heater 2 is controlled by the temperature control circuit in accordance with the temperature detected by the temperature sensing element 6, and the surface temperature of the fixing roller 1 is automatically managed to a predetermined heat fixing temperature. Reference numeral 7 denotes a separation claw that separates the recording material P from the surface of the fixing roller 1, and is disposed such that a leading edge portion thereof is brought into contact with the surface of the fixing roller 1 with an appropriate pressure. Reference numeral 8 denotes a cleaner such as a felt that is brought into pressure contact with the surface of the fixing roller 1 and wipes and removes toner tc, paper dust, and the like attached to the surface of the fixing roller 1. Reference numeral 9 denotes a bottom plate made of a metal material of the fixing device. Reference numerals 10 and 11 denote recording material entrance guides and exit guides.

The recording material P that has entered the fixing device through the entrance guide 10 enters the nip portion between the fixing roller 1 and the pressure roller 3 that are in rotational contact with each other by pressing and contacting each other. 3 through the nip. During this passage, the unfixed toner image ta on the recording material P is fixed as a permanently fixed image by heat and pressure.

The recording material P, which has passed through the nip portions of the rollers 1 and 3 and has undergone image fixing, has its leading end separated from the surface of the fixing roller 1 by a separation claw 7 and discharged out of the fixing device through an exit guide 11. .

[0007]

However, according to each of the above conventional examples, there are the following problems. According to the conventional example shown in FIG. 7, if a temperature-sensitive element is provided on the surface of the paper passing portion of the fixing roller, the surface of the fixing roller is damaged at the contact portion, and an offset is generated due to a decrease in releasability. . Further, when the sheet is brought into contact with the surface of the non-sheet passing portion, even if the temperature of the sheet passing portion of the fixing roller changes due to the sheet passing, it may be difficult to detect the change by the temperature sensing element.

On the other hand, when the temperature-sensitive element is brought into contact with the inner surface of the fixing roller, there is a problem that the temperature of the temperature-sensitive element is heated by the direct radiation from the radiation heating element, and the temperature of the roller cannot be measured accurately.

When the thickness of the fixing roller is large,
A large thermal gradient is generated between the surface and the inner surface, and the temperature detected on the inner surface may not always reflect the surface temperature. In such a case, problems such as poor fixing have occurred.

Further, according to the conventional apparatus shown in FIG. 7, since the temperature-sensitive element and the holding member that holds the temperature-sensitive element and abuts on the fixing roller are set in the paper area, the use of the apparatus is difficult. Temperature control by causing the offset prevention layer on the fixing roller surface to damage and lowering the releasability, causing offset, and causing toner or paper powder to adhere to the temperature-sensitive element and lowering the thermal responsiveness of the temperature-sensitive element There is a possibility that the temperature or the power cutoff temperature at the time of abnormal temperature rise may be increased. Further, the toner adhering to the temperature-sensitive element slips through the sheet immediately after startup from room temperature and is fixed on the sheet, causing image stains.

An object of the present invention is to solve the above problems and to provide a fixing device capable of appropriately measuring the temperature of the fixing roller without damaging the surface of the fixing roller.

[0012]

According to the present invention, an object of the present invention is to provide a fixing device having a hollow fixing roller and a temperature sensing element for detecting a temperature of the fixing roller. grooves in the circumferential direction is provided, it said temperature sensitive device is achieved by being abutting against the bottom of the groove.

[0013]

According to the present invention, since the temperature sensing element is mounted on the inner surface of the fixing roller, the surface layer of the fixing roller is not damaged, and the disposing position is provided on the inner surface of the fixing roller in the circumferential direction. Since the position is in contact with the bottom of the groove within the groove, the temperature is accurately detected without being affected by the direct radiation from the radiation heating element and regardless of the thickness of the fixing roller.
Furthermore, since it is attached to the inner surface of the fixing roller, it can be attached to a portion corresponding to the paper passing portion of the fixing roller, and accurately detects a temperature change due to paper passing.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 1 to 4 of the present invention will be described with reference to the drawings.

First Embodiment First, a first embodiment of the present invention will be described with reference to FIGS. The apparatus of this embodiment is a fixing device as an image heating and fixing device in an image forming apparatus (not shown). FIG. 1 is a longitudinal sectional view showing a main part of the fixing device, and FIG. 2 is a roller axial direction in an XY plane. It is sectional drawing and the same code | symbol is attached | subjected to the common part with the above-mentioned conventional example.

In FIG. 1, a fixing roller 1 has an anti-offset layer 1 on the surface of an aluminum cored bar 101 having a thickness of 3 mm.
02 is a PFA tube coated. Further, the inner surface of the fixing roller 1 is subjected to a known antireflection processing so as to easily absorb radiation.

The heater 2 uses a halogen heater.
It has an output of 600 W (when 115 V is input) and has the ability to sufficiently raise the temperature of the fixing roller 1. The pressure roller 3 has a core metal 301 provided with a silicone rubber layer 302 and is made of ASK.
The hardness at ER-C is 40 degrees or less. In this embodiment, the diameter of the fixing roller 1 and the pressure roller 3 is 30 mm, and the pressure is adjusted so that the fixing nip is 4 mm or more.

The groove D shown in FIG. 2 is formed at a position 22 mm in depth from the inner surface of the fixing roller at an axial position at the end of the width of the minimum size paper, and the surface of the groove D is polished to reduce slipperiness. Secured. The fixing roller 1 is driven by providing a drive gear at an end opposite to the side where the groove D is provided,
The configuration is such that the groove D of the fixing roller 1 having reduced strength is protected.

The temperature sensing element 6 is enclosed in glass beads having a diameter of 1 mm, is held by a holding member 601 made of alumina, and is in contact with the bottom of the groove D.

In this embodiment, the temperature-sensitive element 6 is sealed in glass beads. However, the temperature-sensitive element 6 may be protected by a simpler Kapton tape or a thermocouple element. Further, since the temperature sensing element 6 is in contact with the inside of the fixing roller, the installation position in the axial direction is free. Even when the temperature sensing element 6 is set at the center, for example, the sheet passing position, there is no effect on the image, and the temperature contributing to the fixing property is not affected. Can be detected directly. Furthermore, even when a plurality of temperature sensing elements are installed at different positions to monitor the temperature of the fixing roller 1, a high-quality fixed image can be maintained without damaging the surface of the fixing roller 1. This is an effective feature for preventing the temperature of the non-sheet-passing portion from rising in an image that requires passing of transfer sheets of various sizes.

Unlike the case where the temperature-sensitive element 6 contacts the surface of the fixing roller 1, the temperature-sensitive element 6 of the present embodiment does not need to consider the releasability of the surface of the fixing roller.
The heat resistance and heat capacity of the temperature-sensitive element 6 are extremely small, and a configuration excellent in thermal response is obtained. The bottom of the groove D reflects the temperature of the surface of the fixing roller 1 which directly contributes to the fixing property,
With this configuration, it is possible to detect this temperature and control the temperature, and it is possible to ensure sufficient fixing performance without overshoot.

FIG. 3 shows a fixing roller 19 in this embodiment.
Although the temperature was controlled at 0 ° C. (solid line), there was almost no difference even when compared with the conventional temperature control performed by contacting the fixing roller surface (dotted line), indicating that the temperature was accurately controlled. . Further, since the thermal resistance and the thermal capacity of the thermosensitive element 6 are small, there is almost no overshoot even when the temperature is raised from room temperature.

In this embodiment, since the temperature-sensitive element 6 is brought into contact with the inner surface of the fixing roller 1, there is no need to worry about impairing the paper clearance, and it is possible to make contact with the vicinity of the fixing nip. Therefore, a more essential temperature can be detected for securing the fixing property.

Embodiment 2 Next, Embodiment 2 of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

This embodiment is a fixing device as an image heating and fixing device in an image forming apparatus (not shown). FIG. 4 is a longitudinal sectional view showing a main part of the fixing device.

In FIG. 4, the fixing roller 1 has an anti-offset layer 1 on the surface of an aluminum core bar 3 having a thickness of 3 mm.
02 is PTFE resin coated at 30 μm. Further, the inner surface of the fixing roller 1 is subjected to a known antireflection processing so as to easily absorb radiation.

The heater 2 uses a halogen heater.
It has an output of 600 W (when 115 V is input) and has the ability to sufficiently raise the temperature of the fixing roller 1. The heater 2 is disposed at a position closer to the nip when viewed from the center of the core 101 of the fixing roller, so as to effectively use radiant energy.

The pressure roller 3 has a core metal 301 provided with a silicone rubber layer 302 and has a hardness of 4 in ASKER-C.
0 degrees or less.

In this embodiment, the diameter of the fixing roller 1 and the pressure roller 3 is 30 mm, and the pressure is adjusted so that the fixing nip is 4 mm or more.

Also in this embodiment, a groove D is provided, and the groove D has a depth of 2 m from the inner surface of the fixing roller 1 in the paper passing area.
m, and the surface of the groove D is polished to ensure slipperiness.

Reference numeral 12 shown in FIG. 4 denotes a mirror plate made of mirror stainless steel provided inside the fixing roller 1, and the inner surface of the fixing roller 1 which spreads the radiation from the heater 2 from the most downstream of the nip to the rotation upstream of the fixing roller 1. At an azimuth of about 80 °. As a result, 50 to 60% or more of the radiation energy of the heater 2 (the heater 2 is at the center of the fixing roller 1 and 40% or less when there is no reflector) is fixed to the fixing roller 1.
Can be used to raise the temperature of This is considered to be an effect that the radiation from the fixing roller 1 can be reduced by reducing the radiation directed in directions other than the nip direction.

On the other hand, the reflection plate 12 also has a function of blocking radiation from the heater 2 over about 280 ° of the inner surface of the fixing roller 1 extending from the most downstream of the nip to the rotation downstream of the fixing roller 1. The present embodiment is characterized in that the area where the radiation is blocked is selected as the place where the temperature-sensitive element 6 is installed. In this embodiment, the most suitable position is the position immediately after the fixing nip (groove D). I chose. This has a feature that the temperature of the fixing nip can be accurately measured, and that the heating of the temperature-sensitive element 6 by direct radiation from the heater 2 can be suppressed. The bottom of the groove D indicates the temperature near the surface of the fixing roller that contributes to the fixing property as described above, and by detecting this, it becomes possible to perform appropriate temperature control.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view showing a main part of the fixing device according to the present embodiment.

In FIG. 6, the fixing roller 1 is formed by coating a surface of an iron core metal 101 having a thickness of 2 mm with a PFA resin as an anti-offset layer 102 by 30 μm. The inner surface of the fixing roller 1 is subjected to anti-reflection processing so as to easily absorb radiation.

As the heater 2, a halogen heater is used, has an output of 600 W (when 115 V is input), and has an ability to sufficiently raise the temperature of the fixing roller 1.

The pressure roller 3 has a core metal 301 provided with a silicone rubber layer 302 and has a hardness of 4 in ASKER-C.
0 degrees or less.

The diameter of the fixing roller 1 and the pressure roller 3 was 30 mm, and the pressure was adjusted so that the fixing nip was 4 mm or more.

In this embodiment, as shown in FIG. 5, the groove D is formed on the inner surface of the fixing roller in the area where the paper is passed. Thereby, direct radiation from the heater 2 is blocked at the bottom of the groove D, and the heating of the temperature-sensitive element 6 itself can be prevented. Further, by inserting the temperature sensing element 6 along the opening direction of the groove D,
It is possible to reduce the amount of bending of the electrical connection to the temperature sensing element 6 and make it easy to protect.

The temperature sensing element 6 is held by a holding member 601 and is in contact with the bottom of the groove D. Unlike the case where the temperature-sensitive element 6 is in contact with the surface of the fixing roller 1, there is no need to consider the releasability of the surface of the fixing roller, so that the protective material and the like can be simplified, and the thermal resistance and heat capacity of the temperature-sensitive element 6 can be improved. Becomes extremely small, resulting in a configuration excellent in thermal response. The bottom of the groove D reflects the temperature of the surface of the fixing roller 1 which directly contributes to the fixing property. With this configuration, it is possible to detect this temperature and adjust the temperature, so that there is no overshoot, and High fixability can be ensured.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, the same reference numerals are given to the same parts as those in the above embodiment, and the description is omitted.

In FIG. 6, the fixing roller 1 has a heating layer 103 covering the surface of a 2 mm-thick alumina cored bar 101.
Further, a PFA resin is coated as the offset prevention layer 102.

The heat generating layer 102 is made of a carbon dispersed conductive resin and has an output of 500 W (when 115 V is input).

The pressure roller 3 has a core metal 301 provided with a silicone rubber layer 302 and has a hardness of 4 in ASKER-C.
0 degrees or less.

In this embodiment, the fixing roller 1 and the pressure roller 3
The size of the diameter was 25 mm, and the pressure was adjusted so that the fixing nip was 3 mm or more.

The groove D is processed to a depth of 1 mm from the inner surface of the fixing roller.

The temperature sensing element 6 is a holding member 6 made of aluminum.
01 and is in contact with the bottom of the groove D.

This embodiment is applied to a fixing device using a fixing roller having a surface heating element according to the present invention. In general, in this method, the temperature-sensitive element 6 is brought into contact with the surface of the fixing roller 1. In addition, not only may the releasability of the fixing roller 1 be reduced, but also the surface heat-generating layer may be damaged. Therefore, it is preferable that the fixing roller is hollow and the temperature-sensitive element is brought into contact with the inner surface. Further, since the heat capacity can be reduced by forming the fixing roller in a hollow structure, there is an advantage that the rise time can be reduced.

However, if the temperature sensing element 6 is merely brought into contact with the inner surface of the fixing roller 1 as in the conventional example, there is a large difference between the surface temperature and the inner surface temperature. It was difficult. A method of reducing the temperature gradient by reducing the thickness of the core of the fixing roller 1 is also conceivable. However, if the thickness of the fixing roller 1 is too small, the flow of the heat flow in the axial direction is deteriorated, and a locally high-temperature portion is generated. Up to that point.

The present embodiment shows a preferred example in which the present invention solves such a problem.

[0050]

As described above, according to the present invention,
In a fixing device that heats and presses a recording material carrying an unfixed toner image to fix the unfixed toner image on the recording material, the fixing device includes a hollow fixing roller and a temperature-sensitive element that detects a temperature of the fixing roller. A groove is provided in the inner surface of the fixing roller in a circumferential direction ,
Since the temperature sensing element is brought into contact with the bottom of the groove, even when a thick roller is used, the temperature of the surface can be accurately detected, and the overshoot is suppressed to a low level and the thermal deterioration of the member is suppressed. Was prevented, and the fixability was improved.
Furthermore, since there is no friction between the temperature-sensitive element and the surface of the fixing roller, it is possible to prevent the accumulation of dirt and the like in the abutting portion to degrade the temperature control without deteriorating the releasability of the fixing roller.
Problems such as dirt slippage were also solved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of an apparatus according to a first embodiment of the present invention.

FIG. 2 is an axial sectional view of a fixing roller of the apparatus shown in FIG.

FIG. 3 is a diagram showing an experimental example using the apparatus in FIG. 1;

FIG. 4 is a longitudinal sectional view showing a main part of an apparatus according to a second embodiment of the present invention.

FIG. 5 is a sectional view in the axial direction of a fixing roller according to a third embodiment of the present invention.

FIG. 6 is a longitudinal sectional view showing a main part of a device according to a fourth embodiment of the present invention.

FIG. 7 is a diagram illustrating a schematic configuration of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Radiation heating element 3 Pressure roller 6 Temperature sensing element D groove X Non-application area width (left and right end non-image part) Y High resistance coating layer width (left and right end non-image part)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuko Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tatsunori Ishiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Non-corporation (72) Inventor Tatsuichi Tsukita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masahiro Goto 3-2-2 Shimomaruko, Ota-ku, Tokyo Canon Stock Within the company (72) Inventor Koichi Hiroshima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Koichi Tanigawa 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. ( 72) Inventor Katsuhiko Nishimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tohru Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor: Satoshi Tsuruya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-122969 (JP, A) JP-A-57-60362 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (1)

(57) [Claims] 1. A fixing device having a hollow fixing roller and a temperature-sensitive element for detecting a temperature of the fixing roller , wherein a groove is provided in an inner surface of the fixing roller in a circumferential direction, and the temperature-sensitive element is the fixing device characterized in that it abutting against the bottom of the groove.