JPS58172671A - Roll type heat fixing device - Google Patents

Abstract

PURPOSE:To enable instantaneous detection of surface temp. stably without errors and without being disturbed by convection and air stream, by installing a noncontact type temp. detector for detecting energy radiated from the high temp. surface of a roll type heat fixing device at a position unaffected by disturbance of the air heated with said device. CONSTITUTION:A noncontact thermoelectromotive force type IR detector 8 is installed opposite to the circumference of a heating roll at a position apart from the circumference by a distance l and at a height same as that of the center of the heating roll 1. Radiation rays emitted from the roll 1 reach the photosensor 9 of the detector 8, and the temperature gradient caused by this heat absorption is detected as a thermoelectromotive force with a thermocouple. A controller receives the detection signal of the detector 8, and controls the surface temp. of the roll 1 to a set required temp. near 200 deg.C. Since the detector 8 is an IR detector, it is not directly affected by heat convection, and it appears as noise of the output of the sensor, but exerts no effect on the output level. Even if the surrounding air causes heat convection or upward flow due to the roll 1, since the detector 8 is located at the height equal to that of the center of the roll and apart from these streams, it is not affected unfavorably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a roll-type heat fixing device equipped with a non-contact temperature detector that detects radiant energy emitted from the body.

Conventionally, as a fixing device of a copying machine, a powder toner image is heated onto a sheet using a heating roll and a pressure roll.
Roll-type heat fixing devices are widely used.

In addition, contact detectors and non-contact detectors are used to detect the temperature of the high-temperature surface of a roll-type heat fixing device, especially the heating roll surface (the pressure roll surface may also receive heat from the heating roll and be heated to a high temperature). However, non-contact type detectors are advantageous over contact type detectors in terms of heating roll wear, sensor wear, lifespan, etc.

However, non-contact temperature detectors that utilize heat-induced changes in the resistance of elements (for example, thermistors) are greatly affected by convective heat around the sensor in addition to radiant heat from the heating roll. When the temperature changes, the amount of heat to be detected also changes, causing the temperature of the heating roll to be detected incorrectly.As a result, a toner with a wide range of fixable temperatures is required.

The present invention relates to an improvement of a roll-type heat fixing device that overcomes such difficulties, and the powder toner image is transferred to the sheet while the sheet on which the powder toner image is formed is conveyed under pressure by a heating roll and a pressure roll. In a roll-type heat-fixing device that heats and fixes the air on the surface of the roll-type heat-fixing device, a non-contact temperature detector that detects radiant energy emitted from the high-temperature surface of the roll-type heat-fixing device is installed in the air heated by the heat-fixing device. It is characterized by being installed in a place that is not subject to shaking, and its [1]
The object of the present invention is to provide a roll-type heat-fixing device that can always stably and accurately detect the high-temperature surface temperature of the roll-type heat-fixing device without delay and control the temperature to a desired temperature.

The present invention provides a roll-type heat fixing device that sorts and heat-fixes a sheet on which a powder toner image has been formed while conveying the sheet under pressure between a heating roll and a pressure roll. , a non-contact temperature detector that detects radiant energy emitted from the high-temperature surface of the roll-type heat-fixing device is installed in a location that is not affected by the fluctuations of the air heated by the heat-fixing device. The temperature of the high-temperature surface of the heat-fixing device can always be detected stably and instantly without error without being affected by convection or airflow disturbances caused by the fixing device.

In the embodiment shown in FIGS. 1 and 2 below, 1 is a heating roll in a roll-type heat fixing device of an electrophotographic copying machine, and the heating roll 1 has a built-in heater (not shown). The surface temperature of the heating roll 1 is controlled to a required value of about 20,000 by a control signal from a temperature control device (not shown).

Further, a pressure roll 2 is pivotally supported below the heating roll 1 in close contact therewith, and the heating roll 1 and the n1 pressure roll 2 are driven to rotate in mutually opposite directions, and the toner image 12
The sheet 11 on which is formed is pressed between the heating roll 1 and the pressure roll 2, and the toner image 12 is heated and fixed on the sort 11 by the heat and pressure between them.

Further, a paper guide 3 is disposed on the discharge side of the heating roll 1 and the pressure roll 2.
A peeling claw 4 is arranged in contact with.

Furthermore, a cleaning plate 5, an oil supply 117, a metering blade 7, and a metering blade 7 are disposed above the heating row A-1 and in contact with the heating row A-1.

[111] A non-contact thermoelectric infrared detector 8 is installed on the circumferential surface of the heating roll 1 at the same height as the center of the heating roll 1 and at a distance l from the circumferential surface of the heating roll l. It is oriented and arranged.

Furthermore, the non-contact thermovoltaic infrared detector 8 can be constructed by connecting both contacts of one or more thermocouples to the central infrared absorber sensing section 9 and a substrate (not shown). The outer periphery of the sensing section 9 of the infrared detector 8 is surrounded by a housing 10 so that the viewing angle at the sensing section 9 of the infrared detector 8 is α (200 degrees in the embodiment).

Note that temperature changes in the substrate are compensated for by providing a diode or the like within the sensor.

Therefore, the distance l is a value that satisfies the following relationship.

α ≦ θ (This does not apply if there is no high-temperature object in the pond within α, that is, if the amount of infrared rays received by the sensor sensing part is not affected by other objects). Note that r is the diameter of the heating roll 1, and θ is the occupied angle of the infrared detector 8 with respect to the diameter direction of the heating roll 1 (the third
(see figure).

Since the embodiment shown in FIGS. 1 and 2 is constructed as described above, the radiation emitted from the heating roll 1 is transmitted to the sensing portion 9 of the non-contact thermoelectric infrared detector 8. The temperature gradient generated by the heat absorption is detected as a thermoelectromotive force by a thermocouple.

A control device (not shown) which receives the detection signal from the detector 8 controls the surface temperature of the heating roll 1 to a required set temperature of about 200°O.

Note that since the detector 8 is an infrared detector, it is not affected by thermal convection like other non-contact sensors using a thermistor or the like, but the infrared rays pass through the window 14 of the sensor and enter the sensor. As mentioned above, since the sensor output is based on the temperature gradient between the sensing part and the substrate, fluctuations in the heat flow around the sensor appear as noise in the sensor output. However, this does not affect the output level.

Furthermore, even if the surrounding air generates heat Z- by the heating roll 1 or an upward flow 13 is generated by a fan (not shown) as shown in FIG. Since the type infrared detector 8 is located at the same height as the center of the heating roll 1 and placed outside this 1:3 flow, it is not affected by these adverse effects at all.

Furthermore, the occupied angle θ of the infrared detector 8 with respect to the heating roll 1
is equal to or larger than the viewing angle α of the detector 8, so that the surface temperature of the heating roll 1 can be accurately detected without receiving radiation from sources other than the heating roll 1 of the object to be measured.

In particular, when the angle is set to θ-45°, the detection response is much better than that at θ-IO°, as shown in FIG.

In the embodiment shown in FIGS. 1 and 2, the infrared detector 8 is installed at the same height as the center of the heating roll 1, but as shown in FIG. Even if installed at locations B and O within an angle range of 15° above and below the horizontal plane from the center of
It is possible to achieve the same monthly effect as in the above embodiment.

However, the infrared detector 8 is
3, as shown in Figure 5, E.
Disturbances occur in the output of the detector 8, reducing reliability.

In addition, if the area around the heating roll 1 is subject to strong air flow from a fan (not shown), the infrared detector 8 may be replaced with a sheet that is transparent to infrared rays, except for the detection radiation receiving surface, or the entire circumference of the infrared detector 8. A rectifying grid or the like that is transparent to infrared rays, such as that used in wind cylinders, may be provided in front of the detection radiation receiving +fti to eliminate the influence of fluctuations due to the air flow.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view illustrating an embodiment of a roll-type heat fixing device according to the present invention, FIG. 2 is an enlarged vertical sectional side view of the main part thereof, and FIG. 3 is an explanatory diagram illustrating the principle of the embodiment. , FIG. 4 is an explanatory diagram illustrating the placement relationship of the detector in the above embodiment, other embodiments, and cases not covered by the present invention, FIG. 5 is a detection characteristic diagram thereof, and FIG. FIG. 7 is a detection characteristic diagram at the occupation angle of the detector in other cases. DESCRIPTION OF SYMBOLS 1... Heating roll, 2... Pressure roll, 3... Paper guide, 4... Peeling claw, 5... Cleaning plate l°, 6... Oil supply wick, 7... Metering blade, 8... Infrared detector, 9... Sensing section, 10...) 1 Uzing, 11... Sorting, 1
2... Toner image, 13... Flow, 11... Window. Agent: Patent attorney Nozomi Ehara and 1 other person Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] The sheet on which the powder toner image has been formed is heated and pressurized.
In a roll-type heat fixing device that heats and fixes the powder toner image on a sheet while conveying the powder toner image under pressure using a roller,
A roll characterized in that a non-contact temperature detector for detecting radiant energy emitted from the high-temperature surface of the roll-type heat-fixing device is provided at a location where the air heated by the heat-fixing device is not affected. Mold heating fixing device.