JP2002365964A - Fixing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing machine which uses a temperature-detecting method, by which the temperature is prevented from being detected as temperature lower than the actual one, even when the infrared absorption film of a non-contact temperature detection means is soiled by toner, in order to prevent deterioration caused by the abnormal temperature rise of the fixing machine. SOLUTION: In this fixing machine provided with a heating member and the non-contact temperature detection means for detecting the surface temperature of the heating member, the non-contact temperature detection means is provided with the infrared absorption film, arranged opposed two the heating member and a film temperature detection means for detecting the temperature of the infrared absorption film, and then an infrared absorption rate that infrared rays in a wavelength region radiated from the heating member are absorbed by the infrared absorption film is the same as or smaller than the infrared absorption rate so that they are absorbed by toner and wax to be used and oil applied to the heating member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used for an electrophotographic device, an electrostatic recording device, and the like, and more particularly, to a fixing device in which a temperature detecting element is arranged in a heating element in a non-contact manner.

[0002]

2. Description of the Related Art A roller type fixing device using a heat roller heated by a halogen heater, a belt type fixing device for heating a heat resistant belt by a ceramic heater or a halogen heater, and the like are used in image forming apparatuses such as copying machines and laser printers. Is often used in

In such a fixing device, a thermistor for maintaining the surface temperature of the heat roller at a predetermined temperature, a temperature fuse for shutting off a current supply path to a heater when the temperature of the heat roller rises abnormally, a thermoswitch, etc. In many cases, the temperature detecting means is brought into contact with the surface of a fixing roller or a fixing belt in contact with the recording material.

[0004] For this reason, contact flaws may occur on the surface of the fixing roller or the fixing belt, causing problems such as white streaks, black streaks, and defective fixing.

Therefore, a method of contacting the temperature detecting means with the surface of the fixing roller or the fixing belt outside the image area, which is the area where the recording material passes, is considered. However, it is impossible to detect the temperature in the image area. In order to increase the size of the fixing device, a method has recently been considered in which the temperature detecting means is brought into non-contact with the fixing roller in the image area.

The non-contact temperature detecting means includes a casing having an opening, an infrared absorbing film which is provided in the casing and is made of a polymer material which absorbs infrared rays passing through the opening, and is in close contact with the infrared absorbing film. A thermistor element for film temperature detection arranged as
A temperature compensating thermistor element for detecting an ambient temperature is provided near the film temperature detecting thermistor element. In this non-contact temperature detecting means, the temperature of the infrared absorbing film rises due to the infrared light having passed through the opening of the casing being absorbed by the infrared absorbing film disposed immediately below the opening, and the infrared light is closely attached to the infrared absorbing film. The thermistor element for detecting the temperature of the film, which is disposed as described above, detects the temperature change. A temperature compensating thermistor element for measuring the ambient temperature in the casing is disposed near the film temperature detecting thermistor element. By detecting the temperature difference between the thermistor element for film temperature detection and the thermistor element for temperature compensation as a potential difference by a bridge circuit, the absolute amount of infrared light passing through the opening is detected, and the temperature of the object to be measured is not contacted. Is to be measured.

In such a temperature detecting means, the temperature of the fixing roller or the fixing belt is detected by measuring the temperature of the film that has absorbed infrared rays. Therefore, by increasing the infrared absorptivity of the infrared absorbing film, it is possible to increase the difference in resistance between the temperature compensating thermistor element and the infrared detecting thermistor element when a certain amount of infrared light is absorbed by the infrared absorbing film. Thus, the temperature detecting capability of the temperature detecting means can be improved. Therefore, a method of mixing carbon black with the infrared absorbing film or painting the surface of the infrared absorbing film with a black body paint has been considered.

However, the non-contact temperature detecting means detects a temperature change of the infrared absorbing film which has absorbed the infrared rays emitted from the target fixing roller or fixing belt. If the toner is scattered in the inside, the wax contained in the toner, or the silicone oil applied to the fixing roller or the like as a release agent is stained, the detected temperature shifts, and as a result, the temperature is detected as lower than the actual temperature. If this occurs, the temperature of the fixing roller will rise abnormally, causing a problem in safety, and the fixing roller and the like of the fixing device will deteriorate quickly.

[0009]

According to the present invention, in order to prevent the above-mentioned deterioration due to abnormal temperature rise of the fixing roller, even if the infrared absorbing film is contaminated with toner or the like, it is detected as a temperature lower than the actual temperature. It is an object of the present invention to provide a fixing device that uses a temperature detecting method that does not perform the fixing.

[0010]

A fixing device according to the present invention comprises a heating member heated by a heating source, and a non-contacting member disposed in non-contact with the heating member for detecting a surface temperature of the heating member. A non-contact temperature detecting unit, wherein the non-contact temperature detecting unit is arranged to face the heating member by infrared absorption. A film, having a film temperature detecting means for detecting the temperature of the infrared absorbing film, the infrared absorption rate of the infrared absorbing film absorbing infrared radiation emitted from the heating member, the toner, wax in the toner, Alternatively, it is characterized in that it is equal to or smaller than the infrared absorptance absorbed by the oil applied to the heating member.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

A fixing device for fixing an unfixed image on recording paper is arranged at a predetermined position of the electrophotographic apparatus. The electrophotographic apparatus includes an image carrier that forms an electrostatic latent image on the surface, a pre-exposure unit that removes charges on the surface of the image carrier, a primary charging unit that charges the surface of the image carrier to a desired potential, Exposure means for exposing the formed image carrier to form an electrostatic latent image, a developing device for developing the electrostatic latent image on the image carrier with a developer to visualize the image, and an image developed by the developing device A transfer device or the like for transferring the toner image on the carrier to the recording material is provided.

The unfixed toner image transferred to the recording material is fused and fixed by a fixing device having a heated and pressed fixing roller, for example, in the case of a roller-type fixing device. Thus, a desired image can be obtained by appropriately executing each process of image formation by each member. Note that recording paper such as recording paper or OHP paper is used.

A typical configuration example of the fixing device of the present invention will be described with reference to FIG. In FIG. 1, a heating roller 2 serving as a heating member is formed by forming a layer of a heat-resistant elastic body such as silicone rubber or fluorine rubber on a core metal made of a pipe material such as aluminum or iron, and forming PFA (fluororesin), PTFE ( This is a roller coated with a release layer made of polytetrafluoroethylene) or the like. The pressure roller 3 as a pressure member, which is disposed in pressure contact with the heating roller 2 so as to form a nip portion, is also provided on a cored bar made of a pipe material such as aluminum or iron similarly to the heating roller. A roller on which a layer of a heat-resistant elastic material such as silicone rubber or fluorine rubber is formed. A recording material S is passed through a nip portion between the heating roller (heating member) 2 and the pressure roller (pressure member) 3, and the toner T including the wax on the recording material S is heated by the heating roller and the pressure roller. And is heated and pressed to fix the toner.

A heater 4 as a heating source is disposed inside the heating roller 2, and heats the heating roller 2 from the inside. The heater 4 is generally used as a heating source of the fixing device, and includes a halogen heater and the like.

In order to detect the surface temperature of the heating roller 2, a temperature detecting element 5 as a temperature detecting means is disposed in a non-contact manner facing the heating roller 2.
To detect the temperature. Based on the data from the temperature detecting means 5, the surface temperature of the heating roller 2 is set to a predetermined set temperature (print temperature) or a non-fixing standby temperature (standby temperature).
To keep it.

A cleaning web 6 is provided on the heating roller 2 to clean the heating roller 2 by the web 6 in which non-woven fabric is impregnated with oil such as silicon oil, and to release the heating roller 2 from the recording material S. Improve the quality.

Next, the structure of the temperature detecting means 5 will be described with reference to FIG.
This will be described in detail with reference to FIG. The temperature detecting element 5 preferably has a casing 7 made of a material having a high thermal conductivity such as aluminum, and an opening 8 provided on one surface of the casing 7 is made of polyimide or the like that absorbs infrared rays radiated from a heating roller. The infrared absorbing film 9 is provided so as to be closed. The temperature detecting element 5 is arranged in a non-contact manner as shown in FIG. 1 so that the infrared absorbing film 9 faces the heating roller 2. A film temperature detecting thermistor element 10 as a film temperature detecting means is adhered and fixed to the inner surface side of the casing of the infrared absorbing film 9 with an adhesive or the like. In the vicinity of the film temperature detecting thermistor element 10, a temperature compensating thermistor element 11 for measuring the ambient temperature in the casing is preferably provided.

The lead wires 12 of the film temperature detecting thermistor element 10 and the temperature compensating thermistor element 11 are connected to sockets (not shown) provided on the casing 7 so as to be taken out. The temperature compensating thermistor element 11 and the film temperature detecting thermistor element 10 are used by forming a bridge circuit of resistors R1 and R2 as shown in FIG. 3, and the output is a potential difference generated between terminals A and B. , The absolute amount of infrared light is detected.

Next, the operation of the temperature detecting element 5 will be briefly described. First, when infrared rays from a heating roller are incident on the infrared absorbing film 9 attached to the opening 8 of the casing 7, the infrared light is absorbed by the infrared absorbing film 9 and the temperature of the infrared absorbing film 9 is changed according to the amount of infrared light.
That is, the temperature rises according to the temperature rise of the heating roller. Then, the temperature of the infrared absorbing film 9 is transmitted to the film temperature detecting thermistor element 10 which is adhered and fixed to the back surface of the film, and is detected as a resistance change of the film temperature detecting thermistor element. The resistance of the film temperature detecting thermistor element 10 is affected by the ambient temperature, and the temperature corresponding to the ambient temperature is detected by using the temperature compensating thermistor element 11 to eliminate the influence.

The reason why the casing 7 is made of a material having a high thermal conductivity such as aluminum is to improve the followability of the temperature compensating thermistor element 11 to changes in the ambient temperature.

By detecting the temperature difference between the film temperature detecting thermistor element 10 and the temperature compensating thermistor element 11 as a potential difference by the above-described bridge circuit, the temperature of the heating roller 2 can be measured in a non-contact manner. If the temperature of the heating roller 2 is recognized to be excessively high, it is preferable to provide a means for suppressing the heating of the heater 4 in the heating roller 2 in the fixing device.

Although the fixing device of the present invention fixes an unfixed toner image, the infrared absorption rate at which the infrared ray emitted from the heating roller is absorbed by the infrared ray absorbing film may adhere to and contaminate the infrared ray absorbing film. It is characterized in that it has the same or lower infrared absorptance than the toner, the wax in the toner or the silicone oil used as the release agent.

The relationship between the infrared absorbing film and the infrared absorption of the toner, the wax contained in the toner, and the silicone oil used as the release agent will be described below.

In general, the infrared absorptance can be easily measured using a thermopile infrared radiation thermometer or the like.

The absorption rate is, for example, 6 to 12 μm.
When measured at a wavelength of m, the infrared absorptance of the toner is about 0.9 for a four-color toner in model A which is a color copying machine.
6 to 0.97, all four colors are almost 0.965 in model B, and almost all 0.9 colors in model C.
65 and 0.96 for the model D of the monochrome machine. The infrared absorption of the wax and the silicone oil are about 0.93 and 0.98, respectively.

However, comparing infrared absorptance in such a manner is not correct in the present invention. This is because the infrared emissivity and infrared absorptivity have wavelength characteristics for each substance, and only the wavelength range detected by the infrared radiation thermometer used for measuring the infrared absorptivity is compared. is there. In the present invention, there is a problem in the infrared absorption when the infrared absorbing film and the toner, wax, and oil absorb infrared in the wavelength region emitted by the heating roller.

Therefore, to measure accurately, it is necessary to compare the magnitudes of the infrared absorptivity by the measuring method as shown in FIG. That is, the temperature of the heating roller 2 is controlled by a temperature adjusting means 14 such as a thermocouple provided in a portion other than the temperature detecting element 5, and the temperature of the heating roller 2 is controlled by the temperature detecting element 5 to which no dirt such as toner adheres. Measure.

Next, the toner 13 is adhered to the infrared absorbing film 9 of the temperature detecting element 5. If the detected temperature is higher than the previously measured temperature, it can be determined that the infrared absorbing rate has increased, and if the detected temperature is lower, the infrared absorbing rate has decreased. . Therefore, in order to determine whether the setting of the infrared absorption coefficient of the infrared absorbing film attached to the temperature detecting element 5 used in a certain model of the fixing device is appropriate, the infrared rays absorbing film adheres to the heating roller and the infrared absorbing film used in the model. It is important to use potential toners, waxes, and silicone oils to attach each contaminant to the infrared absorbing film and to ensure that the detected temperature shifts to the same or higher in each case. If the detection temperature of all these contaminants deviates high, apply an infrared absorbing film mixed with carbon black or a black body paint, and compare the infrared absorption rate with toner, wax and silicone oil. Then, it is possible to use those with the same or lower, but the maximum absorption rate within the range not exceeding these absorption rates, and to improve the temperature detection capability and prevent the fixing device from deteriorating due to overheating. it can.

Further, if the detection temperature shifts to a certain level with respect to a certain contaminant, it is necessary to lower the infrared absorption of the infrared absorption film. For this purpose, for example, it is possible to set an infrared absorption rate equal to that of a contaminant by adding a suitable amount of carbon black to the base material of the film, for example, polyester.

[0031]

According to the present invention, the infrared absorption of the infrared absorbing film is the same as the infrared absorption of toner, wax or silicone oil, or the infrared absorbing film is made lower, so that the infrared absorbing film has a lower toner absorption. When the toner adheres, the temperature is detected as a temperature higher than the actual temperature, so that the fixing device does not deteriorate due to excessive temperature rise.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a fixing device of the present invention.

FIG. 2 is a diagram illustrating a temperature detecting unit of the fixing device of the present invention.

FIG. 3 is a diagram illustrating a circuit configuration when using a temperature detecting unit.

FIG. 4 is a diagram illustrating an experimental device for measuring the setting of the infrared absorptance when implementing the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing unit 2 Heating roller 3 Pressure roller 4 Heater 5 Temperature detecting element 6 Cleaning web 7 Casing 8 Opening 9 Infrared absorbing film 10 Film temperature detecting thermistor element 11 Temperature compensating thermistor element 12 Lead wire 13 Toner 14 Temperature control means

Continued on front page F term (reference) 2G066 AC07 AC16 BA09 BA55 BB11 BB15 BC11 CA15 CB01 2H033 AA18 AA23 AA42 BA31 BA42 BA58 CA07 3K058 AA42 BA18 CA12 CA70 DA02 GA06

Claims (3)

[Claims] 1. A heating member which is heated by a heating source, and a non-contact temperature detecting means for detecting a surface temperature of the heating member which is provided in non-contact with the heating member. In a fixing device that heats and fixes an unfixed toner image on a recording material by heat, the non-contact temperature detecting unit detects an infrared absorbing film disposed to face the heating member and a temperature of the infrared absorbing film. Having a film temperature detecting means, the infrared absorptivity of the infrared absorbing film absorbing infrared rays in the wavelength range emitted from the heating member is the same as the infrared absorptivity of the toner, or A fixing device characterized by being small. 2. A heating member which is heated by a heating source, and a non-contact temperature detecting means for detecting a surface temperature of the heating member which is provided in non-contact with the heating member. In a fixing device that heats and fixes an unfixed toner image on a recording material by heat, the non-contact temperature detecting unit detects an infrared absorbing film disposed to face the heating member and a temperature of the infrared absorbing film. Having a film temperature detecting means, wherein the infrared absorption of the infrared absorbing film absorbs infrared in the wavelength region emitted from the heating member is the same as the infrared absorption of the wax in the toner. Or
Or a fixing device characterized by being small. 3. A heating member which is heated by a heating source, and a non-contact temperature detecting means for detecting a surface temperature of the heating member which is provided in non-contact with the heating member. In a fixing device that heats and fixes an unfixed toner image on a recording material by heat, the non-contact temperature detecting unit detects an infrared absorbing film disposed to face the heating member and a temperature of the infrared absorbing film. Having a film temperature detecting means, the infrared absorptivity of the infrared absorbing film absorbing infrared rays in the wavelength region emitted from the heating member is compared with the infrared absorptivity of the oil applied to the heating member. A fixing device characterized by being the same or smaller.