JP2003066761A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which can easily and accurately measure a plurality of surface temperatures of a heating roller or a pressure roller in a non-contact state. SOLUTION: In the fixing device which feeds a transfer material with an unfixed toner image formed thereon between the heating roller and the pressure roller and melt-fixes the toner image on the transfer material to the transfer material by heating and pressurization, the surface temperatures of two or more places of the heating roller or the pressure roller are measured in the non-contact by using one temperature sensor.

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 in an image forming apparatus such as a copying machine, a printer and a fax machine, and more particularly to a fixing device for measuring a heating roller or a pressure roller using a non-contact temperature sensor. Regarding

[0002]

2. Description of the Related Art As a fixing device used in an image forming apparatus, an unfixed toner image formed on a transfer material is passed between a heating roller and a pressure roller to heat and apply the toner image on the transfer material. There is known a device for welding the transfer material by pressure. As a method for measuring the surface temperature of the heating roller or the pressure roller in a non-contact manner with a thermopile in which thermocouples are integrated, a plurality of temperature sensors are provided to measure, or one temperature sensor is moved and measured at a plurality of points. The method is known.

[0003]

However, as a problem of the conventional technique, when a plurality of non-contact temperature sensors are provided, the structure becomes complicated and an error may occur between the temperature sensors. Further, the method of moving one temperature sensor to measure a plurality of temperatures requires a moving mechanism of the temperature sensor, which causes a problem that the measurement accuracy is lowered due to a moving error.

The present invention has been made in view of the above problems, and an object thereof is to provide a fixing device capable of easily and accurately measuring the surface temperatures of a plurality of portions of a heating roller or a pressure roller in a non-contact manner.

[0005]

The objects of the present invention can be achieved by the following means. That is, in a fixing device in which a transfer material on which an unfixed toner image is formed is passed between a heating roller and a pressure roller to fuse the toner image on the transfer material to the transfer material by heating and pressing, A fixing device, characterized in that the surface temperature of the heating roller or the pressure roller is measured in a non-contact manner at a plurality of points with a single temperature sensor.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of an image forming apparatus using a fixing device according to the present invention will be described first. FIG. 1 is a sectional configuration diagram of an image forming apparatus using a fixing device according to the present invention, FIG. 2 is an explanatory diagram showing a structure of the fixing device, and FIG. 3 is an enlarged sectional configuration diagram of a heating roller of FIG. is there.

As shown in FIG. 1, a photosensitive drum 10 as an image forming body is provided on the outer periphery of a cylindrical base body formed of a transparent member such as glass or a transparent acrylic resin.
A transparent conductive layer and a photoconductor layer of an organic photosensitive layer (OPC) are formed.

The photosensitive drum 10 is rotated clockwise by the power from a driving source (not shown) with the transparent conductive layer being grounded.

The exposure beam for image exposure can impart an appropriate contrast to the photo-attenuation characteristic (photo-carrier generation) of the photo-conductor layer in the photo-conductor layer of the photoconductor drum 10 which is the image forming point. It has an exposure light amount of a wavelength. As a material of the translucent substrate, an acrylic resin, particularly a polymer of a methacrylic acid methyl ester monomer, is excellent in translucency, strength, accuracy, surface property and the like. As the translucent conductive layer, a metal thin film made of indium tin oxide (ITO), tin oxide, lead oxide, indium oxide or the like and maintaining translucency is used. Further, various organic photosensitive layers (OPC) can be used as the photoconductor layer.

Scorotron charger 1 as charging means
1. An exposure optical system 12 as an image writing unit and a developing unit 13 as a developing unit, respectively, an image forming process for each color of yellow (Y), magenta (M), cyan (C) and black (K). Prepared for use in the direction of rotation of the photosensitive drum 10 indicated by the arrow in FIG.
They are arranged in the order of C and K.

Scorotron charger 11 as charging means
Is attached close to the photoconductor drum 10 in a direction orthogonal to the moving direction of the photoconductor drum 10 (direction perpendicular to the paper surface in FIG. 1), and is kept at a predetermined potential with respect to the organic photoconductor layer of the photoconductor drum 10. The control drum (not shown) and a corona discharge electrode 11a, for example, a sawtooth electrode is used, and a corona discharge having the same polarity as the toner is used to perform a charging action (negative charging in the present embodiment). A uniform electric potential is applied to.

The exposure optical system 12 for each color has a linear exposure element (LED), which is a plurality of LEDs (light emitting diodes) as light emitting elements for image exposure light, arranged in an array parallel to the axis of the photosensitive drum 10. (Not shown) and a SELFOC lens (not shown) as an equal-magnification imaging element are configured as an exposure unit attached to a holder. Cylindrical holder 20
The exposure optical system 12 for each color is attached and housed inside the base of the photoconductor drum 10.

The exposure optical system 12 as an image writing means for each color is arranged such that the exposure position on the photosensitive drum 10 is between the scorotron charger 11 and the developing device 13 and the developing device 13 is a photosensitive member. The drum 10 is arranged inside the photoconductor drum 10 while being provided on the upstream side in the rotation direction of the drum 10.

The exposure optical system 12 performs image processing on the basis of image data of each color sent from a separate computer (not shown) and stored in the memory, and then forms an image on the uniformly charged photosensitive drum 10. Exposure is performed to form a latent image on the photoconductor drum 10. The emission wavelength of the light emitting element is usually Y, M,
It is preferable that the toner of C has a high light transmittance in the range of 680 to 900 nm.

The developing device 13 as a developing means for each color is
Yellow (Y), magenta (M), cyan (C) inside
Alternatively, a black (K) two-component developer is accommodated, and each has a developing sleeve 13a formed of, for example, a cylindrical non-magnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm. ing.

In the developing area, the developing sleeve 13a is kept in non-contact with the photoconductor drum 10 with a predetermined gap by an abutting roller (not shown), and is placed at the closest position to the rotation direction of the photoconductor drum 10. The developing bias voltage is applied to the developing sleeve 13a at the time of development. The developing bias voltage is a DC voltage having the same polarity as the toner (negative polarity in this embodiment) or a DC voltage superposed with the AC voltage AC. By doing so, non-contact reversal development is performed on the exposed portion of the photoconductor drum 10.

The developing device 13 non-contactly charges the electrostatic latent image on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure optical system 12 to the charging polarity of the photosensitive drum 10. Reverse development is performed with toner having the same polarity as that of (the photosensitive drum is negatively charged in the present embodiment, and the toner has negative polarity).

When the image forming body drive motor (not shown) is started by the start of the image formation, the photosensitive drum 10 is rotated in the clockwise direction shown by the arrow in FIG. 1, and at the same time, the photoconductor is driven by the charging action of the Y scorotron charger 11. Application of electric potential to the drum 10 is started. After the potential is applied to the photoconductor drum 10, the exposure (image writing) by the electric signal corresponding to the first color signal, that is, the Y image data is started in the Y exposure optical system 12 to rotate the photoconductor drum 10. By scanning, an electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface thereof. The latent image is reversely developed by the Y developing device 13 in a non-contact state, and a yellow (Y) toner image is formed on the photosensitive drum 10.

Next, the photosensitive drum 10 is provided with an M scorotron charger 11 on the yellow (Y) toner image.
Potential is applied by the charging action of M to expose the optical system 12 of M.
Exposure (image writing) by an electric signal corresponding to the second color signal of M, that is, the image data of magenta (M),
The non-contact reversal development by the developing device 13 forms a magenta (M) toner image on the yellow (Y) toner image.

By the same process, a cyan (C) toner image corresponding to the third color signal is further obtained by the C scorotron charger 11, the exposure optical system 12, and the developing device 13, and a K scorotron charger 11 is also provided. , Exposure optical system 1
2 and the developing device 13 sequentially form a black (K) toner image corresponding to the fourth color signal, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation. It

As described above, in the present embodiment, Y, M,
The exposure of the organic photosensitive layer of the photoconductor drum 10 by the C and K exposure optical system 12 is performed from the inside of the photoconductor drum 10 through a light-transmitting substrate. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals can form an electrostatic latent image without being shielded by the toner image previously formed, which is preferable. Photoconductor drum 1
The exposure may be performed from the outside of 0.

On the other hand, the transfer material P is sent out from the paper feeding cassette 15 by a sending roller (no code), is fed by a feeding roller (no code), and is conveyed to the timing roller 16.

The transfer material P is synchronized with the color toner image carried on the photosensitive drum 10 by driving the timing roller 16, and the paper charger 1 as a paper charging means.
It is attracted to the conveyor belt 14a by the charging of 50 and is fed to the transfer area. The transfer material P, which is closely conveyed by the conveyance belt 14a, is rotated around the photosensitive drum 10 by a transfer device 14c as a transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in this embodiment) is applied in the transfer area. The color toner images on the surface are collectively transferred to the transfer material P.

The transfer material P on which the color toner image is transferred is
The charge is removed by a paper separation AC static eliminator 14h serving as a transfer material separating unit, separated from the conveyor belt 14a, and conveyed to the fixing device 17.

The transfer material P is sandwiched by the nip portion N formed between the heating roller 17a and the pressure roller 47a, and the color toner image on the transfer material P is fixed and transferred by applying heat and pressure. The material P is sent by the paper discharge roller 18 and is discharged to the tray above the apparatus.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is cleaned by a cleaning blade 19 provided in a cleaning device 19 as an image forming member cleaning means.
It is cleaned by a. The photoconductor drum 10 from which the residual toner has been removed is uniformly charged by the scorotron charger 11 and enters the next image forming cycle.

As shown in FIG. 2, the fixing device 17 includes a heating roller 17a as an upper roll-shaped heat ray fixing rotating member for fixing a color toner image, and a lower side forming a pair with the upper heating roller 17a. Roll-shaped pressure roller 47a
The heating roller 17a has an internal center,
Depending on the light source, a halogen lamp 171g or a xenon lamp (not shown) that emits heat rays such as infrared rays or far infrared rays containing visible light is provided. Further, TS1 is a temperature sensor attached to the upper heating roller 17a for performing temperature control, for example, a temperature sensor capable of measuring a plurality of non-contact types using a thermopile that detects infrared radiation amount, and TS5 is a lower temperature sensor. The temperature sensor attached to the pressure roller 47a on the side is a temperature sensor capable of measuring a plurality of non-contact types using a thermopile for detecting the amount of infrared radiation for controlling the temperature. Details will be described later.

The heating roller 17a, which is provided on the upper side and serves as a rotary member for fixing the heat ray in the form of a roll, has a fixing separation claw TR in the rotating direction of the heating roller 17a from the position of the nip portion N.
3, cleaning roller TR1, heat homogenizing roller TR
4. An oil application roller TR2 is provided, and the heating roller 1 is provided by the oil application roller TR2 in which a felt member impregnated with oil is wrapped around a cylindrical aluminum pipe or paper tube.
Oil is applied to 7a. Cleaning roller TR1
Thus, the toner and oil on the peripheral surface of the heating roller 17a are cleaned. The transfer material after fixing is separated by the fixing separation claw TR3. Further, the heat distribution of heat on the peripheral surface of the heating roller 17a heated by the heat ray absorbing layer 171b is made uniform by the heat homogenizing roller TR4 using a metal roller member having good thermal conductivity such as an aluminum material or a stainless steel material or a heat pipe. To be done. The heat homogenizing roller TR4 equalizes the temperature unevenness in the vertical direction and the horizontal direction of the heating roller 17a accompanying the passage of the transfer material.

The heating roller 17a provided on the upper side for fixing the toner image on the transfer material is a cylindrical light-transmitting substrate 171a and a light-transmitting substance on the outer side (outer peripheral surface) of the light-transmitting substrate 171a. Elastic layer 171d, heat ray absorbing layer 171b, and release layer 1
71c in that order, or as will be described in detail in FIG. 3 in the latter part, a cylindrical light-transmitting substrate 171a and a light-transmitting elastic layer 17 on the outer side (outer peripheral surface) of the light-transmitting substrate 171a.
1d and the outside (outer peripheral surface) of the light-transmitting elastic layer 171d,
It is configured as a soft roller in which the heat ray absorbing layer 171B including the heat ray absorbing layer 171b and the release layer 171c described above is provided in that order. A halogen lamp 171g or a xenon lamp (not shown) that emits heat rays such as infrared rays or far infrared rays containing visible light depending on the light source is provided in the center of the light-transmitting substrate 171a. The heating roller 17a is
As will be described later, the soft roller has high elasticity. The heat ray emitted from the halogen lamp 171g or the xenon lamp (not shown) is absorbed by the heat ray absorbing layer 171b (or the heat ray absorbing layer 171B) to form a roll-shaped heat ray fixing rotary member capable of rapid heating.

Further, the lower roll-shaped pressure roller 47a paired with the upper heating roller 17a is, for example, a cylindrical metal pipe 471a made of an aluminum material, and an outer periphery of the metal pipe 471a. The surface is formed as a soft roller having a rubber roller 471b formed of a thick rubber layer using a silicon material, for example. Further, there is provided a heat homogenizing roller TR4 using a metal roller member having good thermal conductivity, such as an aluminum material or a stainless material, which comes into contact with the surface of the rubber roller 471b and is driven to rotate.
A halogen lamp 47 as a heat source is provided in the center of 71a.
1c may be provided. A flat nip portion N is formed between the upper soft roller and the lower soft roller to fix the toner image.

As shown in FIG. 3, the heating roller 17a has a cylindrical translucent substrate 171a having a thickness (wall thickness) of 1 to 5 mm as shown in the cross section of FIG. 3 (a). A ceramic material such as Pyrex (R) glass or sapphire that transmits heat rays such as infrared rays or far infrared rays from a halogen lamp 171g or a xenon lamp (not shown) is mainly used.

The light-transmissive elastic layer 171d is made of, for example, silicon rubber or fluororubber, and is formed of a heat ray-transmissive silicon rubber layer or a fluororubber layer (base layer) that transmits heat rays. In order to increase the speed of the light-transmitting elastic layer 171d, the base layer is mixed with a powder of a metal oxide such as silica, alumina, or magnesium oxide to improve the thermal conductivity. Layer or fluororubber layer is used. Since the silicone rubber layer and the fluororubber layer have lower thermal conductivity than the translucent substrate 171a using a glass member, they function as a heat insulating layer. Light-transmitting elastic layer 171d
The base layer occupies most of the above, and the amount of compression at the time of pressurization is determined by the rubber hardness of the base layer. The intermediate layer of the translucent elastic layer 171d is coated with fluorine rubber as an oil resistant layer for preventing oil swelling. In addition, the transparent elastic layer 1
Since the wavelength of the heat ray passing through 71d is 0.1 to 20 μm, the filler used as the hardness and thermal conductivity adjusting agent described above has a particle size of ½ or less of the wavelength of the heat ray.
The transparent elastic layer 171d is formed by dispersing fine particles of a heat ray permeable metal oxide such as titanium oxide and aluminum oxide having an average particle diameter of 1 μm or less including primary and secondary particles in a resin binder. May be. By providing the transparent elastic layer 171d, the heating roller 17a is configured as a highly elastic soft roller.

The heat ray absorbing layer 171b is the remaining heat ray emitted from a halogen lamp 171g or a xenon lamp (not shown) and absorbed by the light transmitting base 171a and the light transmitting elastic layer 171d. The resin binder is used so as to form a heat ray fixing rotary member capable of absorbing 90% to 100% of heat rays, which is approximately 100% of the heat rays transmitted through the light-transmitting elastic layer 171a and the light-transmitting elastic layer 171d, by the heat ray absorbing layer 171b and capable of rapid heating. A heat ray absorbing member mixed with powder of carbon black, graphite or the like is used, and the heat ray absorbing member is formed on the outer side (outer peripheral surface) of the light-transmitting elastic layer 171d by spraying.

In addition, the PFA (fluorine resin) tube having a thickness of 20 to 100 μm is coated on the outer side (outer peripheral surface) of the heat ray absorbing layer 171b so as to have good releasability from the toner. Applied, a fluororesin paint applied 20 to 100 μm, and a layer thickness 20 to 500 μm
A mold release layer 171c having a thermal conductivity of ( ^{3 to} 100) × 10 ⁻³ J / cm · s · K is provided (separate type), which is formed by molding silicon rubber or fluororubber of m.

Further, as shown in the cross section in FIG. 3 (b), a heat ray absorbing member mixed with a powder of carbon black, graphite or the like, and a fluororesin (PFA or PTFE) paint or silicon which also serves as a binder and a release agent. The heat ray absorbing layer 1 is used as both the heat ray absorbing layer 171b and the release layer 171c described above with reference to FIG.
A heat ray absorbing layer 171B having releasability by integrally forming 71b and a release layer 171c is formed on the outer side (outer peripheral surface) of the light transmitting elastic layer 171d formed on the outer side (outer peripheral surface) of the light transmitting base 171a. However, it is preferable to form a roll-shaped heat ray fixing rotary member having elasticity.

(Embodiment 1) The fixing device according to Embodiment 1 is designed to measure the surface temperature at a plurality of points of a heating roller or a pressure roller in a non-contact manner with a single temperature sensor. The measurement of the surface temperature of the heating roller will be described as an example, but the measurement of the surface temperature of the pressure roller is the same. FIG. 4 is an explanatory diagram for measuring the surface temperature of the heating roller of the fixing device according to the first embodiment.

As shown in FIG. 4A, the heating roller 17
As described with reference to FIG. 2, a is a cylindrical light-transmissive substrate having heat ray radiating means for emitting heat rays and having a light-transmitting property to the heat ray, and the heat ray is provided outside the light-transmissive substrate. A roll-shaped roller having a light-transmitting cylindrical light-transmitting elastic layer and a heat-ray absorbing layer that absorbs the heat rays outside the light-transmitting elastic layer.

The temperature sensor TS1 is a thermopile in which thermocouples are integrated, and measures temperature by detecting infrared rays emitted from an object in a non-contact manner. The same applies to temperature sensors TS2, TS3, and TS4 described later. The temperature sensor TS1 is composed of a condenser lens L, a plurality of thermocouples S, a temperature circuit TC, and the like. The measurement positions are arranged at a fixed distance through the center of the heating roller 17a, and the surface temperatures of the seven measurement positions a to g are measured in a non-contact manner. The temperature sensor TS1 has a built-in temperature compensation circuit.

Further, as shown in FIG. 4B, another temperature sensor TS2 is applied when the temperature distribution in the longitudinal direction of the heating roller 17a is symmetrical, and the temperature sensor TS2 is a condenser lens. L, multiple thermocouples S, temperature circuit TC
And the like, and the measurement position is arranged at a certain distance from the heating roller 17a. 7 for temperature sensor TS1
The surface temperature of one of the measurement positions a to g is measured. Further, the temperature sensor TS2 also has a built-in temperature compensation circuit.

The temperature measuring method will be described below. The infrared light emitted from the seven measuring positions a of the heating roller 17a is collected by the condenser lens L and measured by each thermocouple S, and the temperature circuit TC is measured. Each temperature can be measured at.

As described above, one temperature sensor can simultaneously measure a plurality of temperatures, and the temperature can be measured easily and with high accuracy. In particular, the measurement method shown in FIG. 4B enables temperature measurement in a narrow space.

(Embodiment 2) In the fixing device according to Embodiment 2, the surface temperature of the paper passing portion and the paper non-passing portion of the heating roller or the pressure roller is measured by one temperature sensor in a non-contact manner. Has become. The fixing device is shown in FIG.
The mechanism is the same except for the configuration shown in FIG. 3 and temperature measurement.
The measurement of the surface temperature of the heating roller will be described, but the same applies to the measurement of the surface temperature of the pressure roller. FIG. 5 is an explanatory diagram for measuring the surface temperature of the heating roller of the fixing device according to the second embodiment.

As shown in FIG. 5A, the heating roller 17
As described with reference to FIG. 2, a is a cylindrical light-transmissive substrate having heat ray radiating means for emitting heat rays and having a light-transmitting property to the heat ray, and the heat ray is provided outside the light-transmissive substrate. A roll-shaped roller having a light-transmitting cylindrical light-transmitting elastic layer and a heat-ray absorbing layer that absorbs the heat rays outside the light-transmitting elastic layer.

The temperature sensor TS3 is composed of a condenser lens L, a thermocouple S, a temperature circuit TC, etc., and a paper passing portion H of the heating roller.
The surface temperature of the measurement position b of 1 and the measurement position a of the non-sheet passing portion H2 is measured without contact. The temperature sensor TS3 has a built-in temperature compensation circuit. The temperature sensor TS3 is arranged at a position shown in FIG. 5A which is offset from the center of the heating roller 17a. 5B shows the surface temperature distribution of the heating roller 17a when the transfer material P shown in FIG. 5A has passed the paper passing portion.

Here, a method of measuring the surface temperature will be described.
When the transfer material P passes through the nip portion, the transfer material P absorbs heat and a temperature change occurs between the sheet passing portion H1 and the non-sheet passing portion H2.
The infrared light emitted from the measurement position b provided on the paper passing portion H1 of the heating roller 17a is collected by the condenser lens L and measured by the thermocouple S, and the temperature is measured by the temperature circuit TC. Similarly, infrared light emitted from the measurement position a provided in the non-sheet passing portion H2 of the heating roller 17a is collected by the condenser lens L and measured by the thermocouple S.
The temperature is measured by the temperature circuit TC. Temperature control is performed based on the result of the above temperature measurement.

As described above, the temperature of the paper passing portion or the non-paper passing portion of the heating roller or the pressure roller can be measured with one temperature sensor, and the temperature can be measured easily and with high accuracy.

(Third Embodiment) In a fixing device according to the third embodiment, when the transfer material passes through the nip portion of the fixing device, the paper passing portion and the non-paper passing portion are detected based on the width size information of the transfer material. The measurement position is determined and the temperature is measured by one temperature sensor.
This fixing device is mechanically the same as the above-mentioned configuration shown in FIGS. 2 and 3 except for the temperature measurement. The temperature measurement will be described using the heating roller 17a as an example, but the same applies to the pressure roller. FIG. 6 is an explanatory diagram for explaining the temperature measurement of the heating roller of the fixing device according to the third embodiment.

As shown in FIG. 6A, the heating roller 17
As described with reference to FIG. 2, a is a cylindrical light-transmitting substrate having heat ray radiating means for emitting heat rays therein and having a light-transmitting property with respect to the heat ray, and a heat ray outside the light-transmitting substrate. On the other hand, the roll-shaped roller is provided with a light-transmitting cylindrical light-transmitting elastic layer and a heat-ray absorbing layer that absorbs heat rays outside the light-transmitting elastic layer.

The temperature sensor TS4 is composed of a condenser lens L, a thermocouple S, a temperature circuit TC, etc., and measures the temperature at three measurement positions a, b, c of the heating roller without contact. The temperature sensor TS4 has a built-in temperature compensation circuit. The temperature sensor TS4 is arranged at a position shown in FIG. 6A which is offset from the center of the heating roller 17a. This is applied when the temperature distribution of the heating roller 17a is symmetrical with respect to the center in the longitudinal direction, and the temperature sensor TS4 measures only one side from the center of the heating roller 17a. The transfer material size detection circuit 51 is a circuit that detects the paper passing width size of the transfer material P, and the temperature control unit 50 is configured to instruct the temperature sensor TS4 at the measurement location based on the detection of the paper passing width size.

6B shows the surface temperature distribution of the heating roller when the transfer material P1 passes the nip portion and the non-sheet passing portion is not cooled, and FIG. 6C shows the transfer material P2. Pass it through,
It is a figure which shows the surface temperature distribution of a heating roller when not cooling a non-paper passing part.

Here, the method of measuring the surface temperature will be described. When the transfer material P1 is selected by the transfer material size detection circuit 51 as the transfer material to be thermally fixed, the temperature control unit 50 is used.
As a result, the temperature sensor TS4 selects the measurement position c as the sheet passing portion H1 and the measurement position b as the position measured by the non-sheet passing portion H2 to measure the temperature. When the transfer material P1 is passed through the nip portion, the transfer material P1 absorbs heat and a temperature change occurs between the paper passing portion H1 and the non-paper passing portion H2. The infrared light emitted from the measurement position c of the heating roller 17a as the paper passing portion H1 is collected by the condenser lens L and measured by the thermocouple S, and the temperature is measured by the temperature circuit TC. Similarly, the heating roller 17a
Infrared light emitted from the measurement position b as the non-sheet passing portion H2 of the sheet is collected by the condenser lens L and measured by the thermocouple S, and the temperature circuit T
The temperature is measured at C. Temperature control is performed according to the result of temperature measurement.

Similarly, as a transfer material to be thermally fixed,
When the transfer material P2 is selected by the transfer material size detection circuit 51, the temperature control unit 50 selects the measurement position b as the position measured by the paper passing portion and the measurement position a as the non-paper passing portion by the temperature sensor TS4. The temperature is selected and measured. When the transfer material P2 passes through the nip portion, the transfer material P2 absorbs heat and a temperature change occurs between the paper passing portion and the non-paper passing portion. The infrared light radiated from the measurement position b as the paper passing portion of the heating roller 17a is collected by the condenser lens L and measured by the thermocouple S, and the temperature is measured by the temperature circuit TC. The infrared light emitted from the measurement position a as the non-sheet passing portion of the heating roller 17a is collected by the condenser lens L and measured by the thermocouple S, and the temperature is measured by the temperature circuit TC. Temperature control is performed according to the result of temperature measurement.

After that, the temperature of the heating roller is controlled based on the measured temperature. As described above, the position where the temperature is measured is selected based on the width size information of the transfer material, and the temperature of the paper passing portion and the paper non-passing portion of the heating roller or the pressure roller can be measured with one temperature sensor. Can measure temperature.

In the embodiment, as the temperature sensor,
Although the thermopile in which thermocouples that detect infrared rays emitted from an object in a non-contact manner are integrated has been described, the present invention is not limited to this. For example, an infrared light sensor using a pyroelectric effect using PZT or PVF ₂ film. As long as it can be measured in a non-contact manner.

[0055]

The above-mentioned structure has the following effects.

According to the first aspect of the present invention, since one non-contact temperature sensor measures a plurality of points, a plurality of surface temperatures of the heating roller or the pressure roller can be easily and accurately measured in a non-contact manner. It became so.

According to the second aspect of the invention, since the non-contact temperature sensor measures the paper passing portion and the non-paper passing portion of the transfer material, a plurality of surface temperatures of the heating roller or the pressure roller are measured. It has become possible to measure easily and accurately without contact.

According to the third aspect of the present invention, one non-contact temperature sensor measures the sheet passing portion and the sheet non-passing portion where the transfer material changes. Therefore, a plurality of surfaces of the heating roller or the pressure roller are used. It has become possible to easily and accurately measure temperature without contact.

According to the fourth aspect of the invention, since the heating roller or the pressure roller is measured in half in the longitudinal direction, a plurality of surface temperatures of the heating roller or the pressure roller can be simply contacted with high precision and small size without contact. Now you can measure.

According to the invention described in claim 5, even in a roller provided with a light-transmitting substrate, a light-transmitting elastic layer, a heat ray absorbing layer, or a thin-walled metal cylindrical roller, a plurality of surface temperatures can be easily brought into contact with each other. It is now possible to measure accurately and compactly.

According to the sixth aspect of the invention, since the measurement is performed at the central portion in the longitudinal direction, the measurement can be performed at an appropriate measurement position.

According to the invention described in claim 7, since the temperature is measured at a plurality of spots by being constituted by a plurality of thermopile elements and one condensing lens, the temperature at a plurality of points of the heating roller or the pressure roller can be measured. It has become possible to easily and accurately measure in a small size.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus using a fixing device according to the present invention.

FIG. 2 is a diagram showing a configuration of a fixing device.

FIG. 3 is an enlarged cross-sectional configuration diagram of the heating roller of FIG.

FIG. 4 is an explanatory diagram for measuring the surface temperature of the heating roller of the fixing device according to the first embodiment.

FIG. 5 is an explanatory diagram for measuring the surface temperature of the heating roller of the fixing device according to the second embodiment.

FIG. 6 is an explanatory diagram for measuring the surface temperature of the heating roller of the fixing device according to the third embodiment.

[Explanation of symbols]

17 Fixing device 17a heating roller 47a Pressure roller 51 Transfer material size detection circuit P, P1, P2 transfer material TS1, TS2, TS3, TS4, TS5 temperature sensor L condenser lens S thermocouple TC temperature circuit a, b, c, d, e, f, g measurement position H1 paper passing section H2 Non-sheet passing part

Claims (7)

[Claims] 1. A fixing device for feeding a transfer material on which an unfixed toner image is formed between a heating roller and a pressure roller to fuse the toner image on the transfer material to the transfer material by heating and pressing. 2. A fixing device, wherein the surface temperature of the heating roller or the pressure roller is measured at a plurality of points in a non-contact manner with a single temperature sensor. 2. The fixing device according to claim 1, wherein the plurality of locations are a paper passing portion and a non-paper passing portion. 3. The fixing device according to claim 2, wherein the measurement positions of the paper passing portion and the non-paper passing portion are determined based on the width size information of the transfer material. 4. The fixing device according to claim 1, 2 or 3, wherein the temperature is measured in a one-sided range from a central portion in the longitudinal direction of the heating roller or the pressure roller to one end thereof. 5. The heating roller has a heat ray irradiation means for emitting heat rays therein, and has a cylindrical light-transmitting base having a light-transmitting property with respect to the heat ray, and the heat-transmitting body is provided outside the light-transmitting base. A roll-shaped roller or a thin-walled metal cylindrical roller provided with a cylindrical light-transmitting elastic layer having a light-transmitting property with respect to heat rays and a heat ray absorbing layer that absorbs the heat rays outside the light-transmitting elastic layer. The fixing device according to claim 1, wherein the fixing device is provided. 6. The fixing device according to claim 1, wherein the measurement position of the paper passing portion is a central portion in the longitudinal direction of the heating roller or the pressure roller. 7. The temperature sensor comprises a plurality of thermopile elements integrating thermocouples and one condenser lens,
The fixing device according to any one of claims 1 to 6, wherein infrared light emitted from a plurality of places of the object is simultaneously detected by a plurality of spots to measure the temperature.