JPH10270151A - Heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating apparatus which prevents fixing failure by enhancing its responsiveness, and by controlling a decrease in temperature to the utmost at a site where a safety temperature detection element of a heating body is arranged. SOLUTION: This heating apparatus for conducting heat from a heating body 3 through a film includes a circuit connected in series with the heating body 3, a power source 14 and a relay 12. A CPU 10 controls energization from the power source 14 to the heating body 3, and is connected to the relay 12 by way of a relay signal line 17. When a safety temperature detection element 15 detects runaway conditions where a voltage remains impressed on the heating body 3, it stops energization from the power source 14 to the heating body 3. In this case, the safety temperature detection element 15 is provided on the relay signal line 17, and is arranged in the position of the heating body 3. When the safety temperature detection element 15 detects runaway conditions based on the abnormal rise in temperature of the heating body 3, the relay 12 is opened to stop energization of the heating body 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is incorporated in an image forming apparatus such as a copying machine, a printer, and a facsimile, and is formed on a material to be heated by an image forming process such as electrophotography, electrostatic recording, and magnetic recording. The present invention relates to a heating device for heating and fixing an unfixed toner image. In particular, the present invention relates to an on-demand type heating device that combines a heating element such as a ceramic heater and a film.

[0002]

2. Description of the Related Art Conventionally, as a heating device of an image forming apparatus,
A hot roller system has been used. This heat roller method
The material to be heated is passed between a fixing roller having a built-in halogen heater or the like and a pressure roller pressed against the fixing roller to heat and fix the material. However, the heat roller method has a problem in that since the heat capacity of the fixing roller is large, preheating is required even during standby when printing is not performed, and it takes time to wait up (start up).

In view of this, an on-demand type heating device which combines a heating element such as a ceramic heater having a small heat capacity and a film with respect to the heat roller system has been proposed and put into practical use. The ceramic heater generates heat when a current flows through a conductive pattern having an electric resistance value printed on a ceramic substrate. The on-demand type heating device has an advantage that the temperature rises at a very high rate because the heat capacity of the substrate and the film of the heating element is very small.

[0004] The temperature control of the on-demand type heating device is performed by controlling the detection voltage of the thermistor adhered to the back surface (the surface opposite to the heating surface) of the substrate of the heating body to be constant. In the on-demand type heating device, since the temperature change of the heating element is very fast, fine power control is required. Therefore, based on the thermistor detection voltage, the CPU as the temperature control means calculates the required power supply, and based on the calculation result, the triac or the like as the switching means turns on / off the power supply to supply power from the AC power supply to the heating element. I try to control.

[0005] By the way, when the CPU fails or the triac fails, the temperature control cannot be performed, and it is considered that the AC voltage is still applied to the heating element. This situation is called runaway. When runaway occurs, the heating element continues to generate heat, and may eventually smoke and ignite, causing a fire. Therefore, some kind of safety measure must be provided to stop runaway. Generally, a thermal fuse is provided at the position of the heating element as a temperature detecting element for safety measures. Thermal fuses were considered to have relatively fast temperature response.

The principle of a conventional temperature control system having a thermal fuse is shown in a block diagram of FIG.

This temperature control system has a circuit in which a heating element 103, a relay 112, a power supply 114, and a temperature fuse 115 as a temperature detecting element for safety measures are connected in series. The relay 112 is connected to the CPU 110. The relay 112 is opened by a command from the CPU 110 to cut off the connection between the power supply 114 and the heating element 103.

The thermal fuse 115 is connected in series between the heating element 103 and the power supply 114, and is provided in contact with the back surface of the heating element 103.
5 melts due to the temperature rise of the heating body 103 (runaway detection), disconnects the heating body 103 from the power supply 114, and stops the power supply from the power supply 114 to the heating body 103.

[0009]

However, according to the conventional temperature detecting element for safety measures, the power supply 1 is disconnected at the place where the disconnection occurs during the runaway (the place where the thermal fuse 115 is attached).
Since it is on the lead wire connecting between the heating element 14 and the heating element 103, it is necessary to increase the current capacity during energization, the distance between contacts after disconnection, and the withstand voltage. Therefore, thermal fuse 1
Inevitably, the size of No. 15 increases, and the heat capacity increases. As a result, the following problems occur.

Since the thermal capacity of the thermal fuse 115 is large, the response is slow.

The heating value of the heating element 103 is W = V × V / R
Since the temperature rise becomes faster in proportion to the square of the input voltage V, when the input voltage is high (for example, 100 to 240 V) like energization to the heating element 103, a safety measure with higher responsiveness is required. Becomes However, it is clear that the slow response as in the prior art is not preferable in terms of security measures.

The thermal fuse 11 having a large heat capacity
5 removes heat from the heating element 103 having a small heat capacity,
The temperature of the portion where the thermal fuse 115 is arranged in the heating element 103 is lowered, and as a result, defective fixing is likely to occur.

The present invention has been made to solve such a problem.

An object of the present invention is to reduce the heat capacity of the heat detecting element for safety measures so that the responsiveness is high and the temperature drop in the portion of the heating element where the temperature detecting element for safety measures is arranged is suppressed as much as possible. An object of the present invention is to provide a heating device that prevents fixing failure.

[0015]

According to a first aspect of the present invention, the object is to slide a film on a fixedly supported heating element, and to slide the film on the opposite side of the film from the heating element. A material to be heated is brought into close contact with the surface, and the material to be heated is moved together with the film to pass through the position of the heating body to apply heat energy from the heating body via the film. And the temperature control means connected to the relay via the relay signal line while controlling the power supply from the power supply to the heating element, and the state where the temperature cannot be controlled and the voltage is applied to the heating element. In a heating device having a temperature sensing element for safety measures that stops energization from the power supply to the heating element when it detects that a runaway has occurred, the temperature sensing element for safety measures is located between the relay and the temperature control means. Connect Is provided on the relay signal line and is disposed at the position of the heating element, and when a runaway is detected due to abnormal temperature rise of the heating element, the relay is opened and the power supply from the power supply to the heating element is stopped. Is achieved.

According to the second aspect of the present invention,
The above object is achieved by a safety measure temperature detecting element of the first invention,
This is achieved by being formed directly on the heating element.

According to the third aspect of the present invention,
The above object is achieved by a safety measure temperature detecting element of the first invention,
This is achieved by a pair of contacts provided on the heating element and connected to the relay signal line, and a bimetal having one end fixed to one contact and the other end being detachable from the other contact. .

According to a fourth aspect of the present invention,
The above object is achieved by a safety measure temperature detecting element of the first invention,
This is achieved by comprising a pair of contacts provided on the heating element and connected to the relay signal line, and a conductive resin connected between the pair of contacts.

According to a fifth aspect of the present invention,
The above object is achieved by a temperature detecting element for safety measures of the fourth invention,
This is achieved by providing the heating element with a mountain-shaped projection protruding toward the conductive resin.

According to a sixth aspect of the present invention,
The above object is achieved by a safety measure temperature detecting element of the fifth invention,
This is achieved by coating the surface of the mountain-shaped projection with a fluororesin.

According to a seventh aspect of the present invention,
The above object is achieved by a safety measure temperature detecting element of the first invention,
A sublimable resin pellet, a coil enclosed in the pellet, and a relay connected to this coil and connected to a relay when detecting a change in inductance when the pellet is sublimated and the coil is deformed. This is attained by being constituted by an inductance detection circuit set to be cut off.

According to an eighth aspect of the present invention,
The above object is achieved by a safety measure temperature detecting element of the first invention,
A pair of electrodes, a sublimable resin pellet provided between the pair of electrodes, and a change in the capacitance between the electrodes when connected to the relay and connected to the relay when the pellet is sublimated. This is achieved by being set to shut off the relay upon detection.

According to a ninth invention of the present application,
The above object is achieved by a temperature detecting element for safety measures according to the eighth invention,
This is achieved by printing one of the electrodes on the heating element.

That is, according to the first aspect of the present invention, when the safety measure temperature detecting element provided between the relay and the temperature control means detects a runaway due to abnormal temperature rise of the heating element, Open the relay and stop energizing the heating element from the power supply.

Since the temperature detecting element for safety measures is provided on the relay signal line, the current capacity at the time of energization and the contact point at the time of disconnection are smaller than those of the conventional example in which the temperature detecting element is provided in series between the power supply and the heating element. The distance and the withstand voltage are reduced, so that the temperature sensing element for safety measures is small, and the heat capacity is reduced. Therefore, responsiveness at the time of runaway is improved. Further, since the heat capacity of the temperature detecting element for safety measures is suppressed to a small value, the temperature drop of the portion of the heating element from which heat is taken by the temperature detecting element for safety measures is suppressed as much as possible, thereby preventing the fixing failure.

According to the second aspect of the present invention, since the safety temperature detecting element is formed directly on the heating element, the responsiveness is further improved.

According to the third aspect of the present invention, when the temperature of the heating element rises abnormally, the bimetal moves away from the contact, thereby opening the relay and stopping the power supply to the heating element.

In the fourth invention according to the present application, when the temperature of the heating element rises abnormally, the conductive resin is melted, so that the relay is opened and the power supply to the heating element is stopped.

According to the fifth aspect of the present invention, since the heating element is provided with the chevron-shaped projection protruding toward the conductive resin, the molten conductive resin is formed on the inclined surface of the chevron-shaped projection. Down along and is reliably separated,
The relay is reliably opened. Further, in the sixth invention according to the present application, since the surface of the chevron-shaped projections is coated with the fluororesin, the molten conductive resin is formed into droplets by surface tension, and is more reliably separated, As a result, the relay is more reliably opened.

According to the seventh aspect of the present invention, when the heating element abnormally heats up and the pellets sublimate, the coil deforms due to the spring property and the inductance L changes. After detecting the change in the inductance L, the relay is opened and the power supply to the heating element is cut off.

According to the eighth aspect of the present invention, when the heating element abnormally heats up and the pellets sublime, the capacitance C between the electrodes changes, and the capacitance detection circuit changes the capacitance C. After detecting, the relay is opened and the power supply to the heating element is stopped.

In the ninth invention according to the present application, one of the electrodes is formed by printing on a heating element, and the temperature sensing element for safety measures is directly formed on the heating element. Equivalent to something. Therefore, the responsiveness is further improved.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS.

(First Embodiment) First, a first embodiment of the heating apparatus of the present invention will be described with reference to FIGS.

FIG. 2 shows an on-demand type heating apparatus according to the present invention. This heating device comprises a heating element 3,
The film 2 is interposed between the heating element 3 for fixing and supporting the heating element 3, the heating element 3, the endless heat-resistant film 2 externally fitted to the heating element support 1, and the heating element 3. It has a pressure roller 4 as a rotating body that forms a nip N and drives the film 2.

Here, the film 2 has a thickness of 1 to reduce the heat capacity and improve the quick start property.
A heat-resistant single-layer film of PTFE, PFA, FEP having a thickness of not more than 00 μm, preferably not more than 70 μm and not less than 10 μm, or polyimide, polyamideimide, PEE
PTFE, PFA, on the outer surface of K, PES, PPS, etc.
A composite layer film coated with FEP or the like can be used. In the present embodiment, a polyimide film whose outer peripheral surface is coated with PTFE is used.

The inner peripheral length of the film 2 and the outer peripheral length of the heater support 1 including the heater 3 are, for example, 3
mm. Therefore, the film 2
The circumference is loosely fitted to the heating element 3 and the heating element support 1 with a margin. Therefore, film 2
When the pressure roller 4 is driven, the roller rotates while sliding on the outer periphery of the heating element 3 and the outer periphery of the heating element support 1.

The heater 3 has a substrate 3a made of ceramic such as alumina, and a width 1 to 1 on the surface of the substrate 3a.
Approximately 1 thickness coated by screen printing on 3mm
It has an electric resistance 3b of, for example, Ag / Pd (silver palladium) of 0 μm and a protective layer 7 made of glass or fluororesin coated on the electric resistance 3b.

The pressure roller 4 is composed of a core 4a and a rubber 4b having good releasability such as silicone rubber provided on the outer periphery of the core 4a, and is connected to the end of the core 4a. It is rotated by driving means (not shown).

According to this heating device, the film 2 is rotated by the rotation of the pressure roller 4, and the film 2 is slid on the heating element 3. And the heating element 3 in the film 2
The material P to be heated is brought into close contact with the surface on the opposite side to the material 2 and the material P to be heated is moved together with the film 2 so as to pass through the position of the heating body 3 and to be heated from the heating body 3 via the film 2 to the material P to be heated. Energy is applied and the fixing process is performed.

A temperature control system of the heating device will be described with reference to FIGS.

First, the principle of the temperature control system will be described with reference to FIG. 1. This temperature control system comprises a heating element 3 and a relay 1
2 and a power supply 14 are connected in series. Further, a bimetal 15 as an example of a temperature detecting element for safety measures is provided on a relay signal line 17 connecting the relay 12 and the CPU 10. As is clear from comparison with FIG. 8 showing the above-described conventional example, in the conventional example,
While a temperature measure element for safety measures (temperature fuse 115) is provided in series between the power supply 114 and the heating element 103, the present invention provides a relay signal line 17 between the relay 12 and the CPU 10. The greatest feature is that a temperature detecting element for safety measures (bimetal 15) is provided on the upper side.

Next, a specific example of the temperature control system will be described with reference to FIG. 3. This temperature control system includes, on the one hand, an AC power source 14, a relay 12, a triac 11, and a power source 14.
The heating element 3 that generates heat by the power supplied from the power supply is connected in series to form a circuit. On the other hand, the thermistor 5, the A / D converter 18, and C
A circuit in which the PU 10 and the triac 11 (straddling the above-described circuit) are connected in series is configured.
The relay 12 is connected to the CPU 10 via a relay signal line 17, is opened by a command signal from the CPU 10, and cuts off between the power supply 14 and the heating element 3.

On a relay signal line 17 between the relay 12 and the CPU 10, a bimetal 15 as a safety measure temperature detecting element is provided. That is, the bimetal 15
It is provided in series with the signal line 17 of the relay and is provided on the back surface of the heating element 3. When the bimetal 15 detects a runaway of the heating element 3, that is, when an abnormal temperature rise of the heating element 3 is detected, the bimetal 15 is in an open state, the signal line 17 of the relay is opened, and the power supply from the power supply 14 to the heating element 3 is stopped. It is to let.

The voltage of the relay signal applied to the relay signal line 17 is generally 5 to 24 V, which is lower than the voltage applied to the conventional heating element of 100 to 240 V. Therefore, according to the present invention, the current capacity at the time of energization, the distance between the contacts at the time of disconnection, and the withstand voltage can be small, the bimetal 15 can be small, and the heat capacity can be small as compared with the conventional example.

The temperature of the heating element 3 is detected by the thermistor 5. The analog detection voltage signal of the thermistor 5 is converted into a digital signal via the A / D converter 18 and then taken into the CPU 10. The CPU 10 calculates a required power supply amount based on the temperature information. Based on this calculation result, the triac 11
Electric power is supplied to the heating element 3 while controlling the phase or the wave number.

As shown in FIGS. 4A and 4B, the temperature sensing element for safety measures is a thermoswitch using a bimetal 15 as shown in FIGS. This bimetal 15
Is provided on the back surface of the heating element 3. That is, the temperature detecting element for safety measures includes two contacts 17a and 17b provided by printing on the substrate 3a of the heating element 3, and a bimetal 15 having one side fixed to the contact 17a by the conductive adhesive 16. Have. The contacts 17a and 17b are connected to the relay signal line 17 (see FIGS. 1 and 2).

In this embodiment, the bimetal 15 is formed directly on the heating element 3 to constitute a temperature detecting element for safety measures. The reason why the temperature detecting element for safety measures can be formed directly on the heating element 3 is that, in the present invention, the temperature detecting element for safety measures is provided on the signal line 17 of the relay. This is because the distance between the contacts and the withstand voltage can be reduced. As described above, when the temperature detecting element for safety measures is formed directly on the heating element 3, the temperature detecting element for safety measures (temperature fuse 115) formed separately from the heating element 3 is brought into contact with the heating element 3. Responsiveness is better than the example.

According to the temperature detecting element for safety measures configured as described above, the power supply to the heating element 3 is stopped at the time of runaway as follows.

When a runaway occurs in which excessive power is supplied to the heating element 3 due to a failure of the CPU 10 or the triac 11, when the bimetal 15 becomes higher than a predetermined temperature, the bimetal 15 warps to the opposite side as shown in FIG. , Away from the contact 17b. Due to the interruption between the contact 17a and the contact 17b, the relay 12 between the heating element 3 and the power supply 14 is opened, and as a result, the heating element 3
Is stopped, and safety is ensured.

By the way, the bimetal 15 may repeat the runaway unless the cause of the runaway is corrected. Therefore, it is preferable that the bimetal 15 does not return to the reverse temperature at the temperature at which the bimetal 15 is separated from the contact 17b. Ideally, it is usually desirable to return when the device has cooled to a temperature that is not in use, for example, a subzero temperature.

It should be noted that the thermoswitch of the present invention cannot be connected in series between a heating element and a power source as in the prior art. The reason for this is that the contacts 17a and 17b are easily burned because the voltage is high and the current is large, and the energization is stopped even in a normal state.

The inventors conducted an experiment for confirming the effect of the present embodiment as follows, using a conventional device as a comparative example. In this experiment, an operation temperature of 158 ° C.
Thermal fuse 115 having a length of 18 mm and a cross-sectional diameter of 6 mm
(See FIG. 8) was used in contact with the back surface of the heating element 3 with heat transfer grease. On the other hand, as a configuration of the present embodiment, the operating temperature is 160 ° C., the width is 3 mm, the length is 15 mm,
A 1 mm thick bimetal 15 was used. The heating element 3 was energized without adjusting the temperature from the state where the heating element 3 reached room temperature. As a result, the thermal fuse 115 operates when the temperature on the back surface of the heating element 3 reaches 220 ° C., whereas in the present embodiment, the bimetal 15 operates near 180 ° C., and the energization to the heating element 3 is stopped. Was.

According to the experimental results, in this embodiment,
It was confirmed that the thermal response became faster. This is because the size of the bimetal 15 is smaller and the heat capacity is smaller than that of the conventional thermal fuse 115.

According to the present embodiment, the heat capacity of the bimetal 15, which is the temperature detecting element for safety measures, can be suppressed to a small value, so that the responsiveness is increased. In addition, the temperature of the portion of the heating element 3 where the bimetal 15 is located can be reduced as much as possible, and defective fixing can be prevented.

Further, the size of the bimetal 15, which is the temperature detecting element for safety measures, can be made smaller than that of the conventional thermal fuse, so that it can be easily manufactured.

In the present embodiment, the bimetal 15 is formed directly on the heating element 3 to constitute a safety temperature detecting element. The reason why the temperature sensor for safety measures can be directly formed on the heating element 3 is that the temperature sensor for safety measures of the present invention is provided on the relay signal line 17, so that the current capacity at the time of energization, This is because the distance between the contacts and the withstand voltage at the time of disconnection can be reduced. When the temperature sensing element for safety measures is formed directly on the heating element 3, it is compared with the conventional example in which the temperature fuse 115 (temperature sensing element for safety measures) formed separately from the heating element 3 is in contact with the heating element 3. As a result, the responsiveness is improved.

(Second Embodiment) Next, a second embodiment will be described with reference to FIGS.

In the first embodiment described above, the bimetal 15 is used as the temperature detecting element for safety measures. However, in the present embodiment, a conductive resin having a heat-melting property is used. That is, in the present embodiment, as shown in FIG.
As in the embodiment, the contact 17 provided on the heating element 3
a and 17b are connected by a conductive resin 21.
This embodiment is also the same as the first embodiment in that the temperature sensing element for safety measures is formed directly on the heating element 3, and the responsiveness is further improved.

Here, the conductive resin 21 melts and breaks at a predetermined set temperature. As the conductive resin 21, a resin obtained by subjecting a thermosensitive pellet used in a thermal fuse to a conductive treatment may be used.
A desired melting temperature can be selected depending on the composition during the conductive treatment.

In particular, in the example shown in the drawing, the substrate 3 a of the heating element 3 protrudes in a mountain shape below the conductive resin 21 to form a projection 22. The chevron-shaped projections 22 are provided to cause the molten conductive resin 21 to flow down along the slopes of the chevron-shaped portions and to be surely separated. In addition, the protrusion 22
Is PFA or P which has good releasability and heat resistance on the surface.
A fluororesin film 23 such as TFE is coated. The fluororesin film 23 is for dropping the molten conductive resin 21 by the surface tension and separating it more reliably.

According to the temperature sensing element for safety measures configured as described above, the relay signal line is cut off at the time of runaway as follows.

When the heating element 3 runs away, the conductive resin 21 melts. The molten conductive resin 21 is formed into a mountain-shaped projection 22.
5 and drops on the fluororesin film 23 formed on the surface of the projection 22 by surface tension.
Complete separation as shown in (b). As a result, contact 1
7a and the contact 17b are cut off, the relay signal line is cut off, the relay is opened, and the power supply to the heating element 3 is stopped.

According to this embodiment, the same effects as those of the above-described first embodiment can be obtained, and further, the structure can be further simplified, and the manufacturing becomes easier.

(Third Embodiment) Next, a third embodiment will be described with reference to FIGS.

The temperature detecting element for safety measures of this embodiment is
Runaway is detected by a change in the inductance L of the coil, and a measure is taken. That is, as shown in FIG. 6A, the temperature sensing element for safety measures of this embodiment includes a pellet 31 made of a sublimable resin, a coil 32 sealed in the pellet 31, Relay signal line 1 extending from coil 32 to outside of pellet 31
7 and an inductance detection circuit (not shown) connected to the relay signal line 17.

The pellet 31 made of the sublimable resin is
And sublimates rapidly above 180 ° C., for example. The coil 32 has a spring property in a contraction direction, and is enclosed in an elongated form in the pellet 31. When the pellet 31 sublimates, the coil 32 contracts due to its spring property. The relay signal line 17 extending from the coil 32 is connected to an inductance detection circuit (not shown). This inductance detection circuit
Runaway is detected by a change in the inductance L of the coil 32, and the relay is opened when runaway is detected.

In the present embodiment, the heating body 3
When the temperature rises, the pellets 31 sublime. Then, the coil 32 contracts as shown in FIG. 6B due to its spring property, and its inductance L changes. When detecting the change in the inductance L, the inductance detection circuit opens the relay, stops the power supply to the heating element 3, and stops the runaway.

According to the present embodiment, similar to the above-described first embodiment, the effects of improving responsiveness and fixing property can be obtained.

(Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIGS.

In the third embodiment, runaway is detected by detecting a change in the inductance L of the coil. On the other hand, in the present embodiment, runaway is detected by detecting a change in the capacitance C of the capacitor.

The temperature detecting element for safety measures of this embodiment is
As shown in FIG. 7A, a pair of electrodes 41a, 41b
And a pellet 42 made of a sublimable resin provided between the electrodes 41a and 41b. The electrodes 41a, 41 of this capacitor
A capacitance detection circuit (not shown) is connected to a relay signal line 17 extending from “b” to constitute a temperature detection element for safety measures.

The capacitor can be easily integrated by forming one electrode 41b on the heating element 3 by printing and attaching the pellet 42 by potting. In addition, since it is in close contact with the heating element 3, the responsiveness is further improved. The device manufactured in this way corresponds to a device in which a temperature detecting element for safety measures is directly formed on the heating element 3.

In this embodiment, the heating element 3
When the temperature becomes high, the pellets 42 sublime (FIG. 7B).
State). Then, the capacitance C between the electrodes 41a and 41b is obtained.
Changes. When detecting the change in the capacitance C, the capacitance detection circuit opens the relay, stops energization of the heating element 3, and stops runaway.

According to the present embodiment, similar to the above-described first embodiment, the effects of improving the responsiveness and the fixing property can be obtained.

[0076]

As described above, the first embodiment according to the present application is described.
According to the invention of the above, the temperature detecting element for safety measures is provided on the relay signal line. In this case, the distance between the contacts and the withstand voltage can be reduced, so that the temperature detecting element for safety measures can be reduced, and the heat capacity can be reduced. Therefore, responsiveness at the time of runaway can be improved. Further, since the heat capacity of the safety measure temperature detecting element can be suppressed to a small value, a temperature decrease in a portion of the heating element where the safety measure temperature detecting element is located can be suppressed as much as possible, thereby preventing a fixing failure.

According to the second aspect of the present invention,
Since the temperature sensing element for safety measures of the first invention is formed directly on the heating element, when the temperature sensing element for safety measures formed separately from the heating element is brought into contact with the heating element, In comparison, the response can be further improved.

According to the third aspect of the present invention,
In the first invention, when the temperature of the heating element rises abnormally, the bimetal separates from the contact, opens the relay, and cuts off the power supply to the heating element.

According to the fourth invention of the present application,
In the first invention, when the temperature of the heating element rises abnormally, the conductive resin is melted, so that the relay is opened and the power supply to the heating element is cut off.

According to the fifth aspect of the present invention,
In the fourth aspect, since the heating element is provided with the mountain-shaped projection protruding toward the conductive resin, the molten conductive resin flows down along the slope of the mountain-shaped projection, and is reliably separated, As a result, the relay is reliably shut off.

According to the sixth aspect of the present invention,
Since the fluororesin is coated on the surface of the mountain-shaped projection according to the fifth invention, the molten conductive resin is formed into droplets by surface tension, is more reliably separated, and the relay is more reliably shut off.

According to the seventh aspect of the present invention,
In the first aspect, when a change in the inductance L when the temperature of the heating element abnormally rises is detected, the relay is opened to cut off the power supply to the heating element. Since the temperature detecting element for safety measures is provided on the relay signal line, the temperature detecting element for safety measures can be made small, and the heat capacity can be suppressed small.
Therefore, responsiveness at the time of runaway can be improved. In addition, since the heat capacity of the temperature sensing element for safety measures can be kept small,
It is possible to minimize the temperature drop in the portion of the heating element where the temperature sensing element for safety measures is located, thereby preventing defective fixing.

According to the eighth aspect of the present invention,
In the first aspect, when a change in the capacitance C between the electrodes when the temperature of the heating element abnormally rises is detected, the relay is opened and the power supply to the heating element is cut off. Since the temperature detecting element for safety measures is provided on the relay signal line, the temperature detecting element for safety measures can be made small, and the heat capacity can be suppressed small. Therefore, responsiveness at the time of runaway can be improved. Further, since the heat capacity of the temperature detecting element for safety measures can be suppressed to a small value, the responsiveness during runaway can be improved. Further, since the heat capacity of the safety measure temperature detecting element can be suppressed to a small value, a temperature decrease in a portion of the heating element where the safety measure temperature detecting element is located can be suppressed as much as possible, thereby preventing a fixing failure.

According to the ninth invention of the present application,
Since one of the electrodes of the eighth invention is formed on the heating element by printing, the responsiveness can be further improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of a temperature control system of a heating device according to the present invention.

FIG. 2 is a schematic configuration diagram showing one embodiment of a heating device of the present invention.

FIG. 3 is a block diagram showing a specific example of a temperature control system of the heating device of FIG. 2;

4 is an enlarged cross-sectional view showing a temperature sensing element for safety measures which is a part of the temperature control system shown in FIG. 3; FIG. 4 (a) shows a state where the bimetal is closed, and FIG. It is a figure showing an open state.

FIG. 5 is an enlarged cross-sectional view showing a temperature sensing element for safety measures which is a part of a temperature control system according to another embodiment, and FIG. 5A shows a state before the conductive resin is melted, (b) is a diagram showing a state after the conductive resin is melted.

FIG. 6 is an enlarged sectional view showing a temperature sensing element for safety measures which is a part of a temperature control system according to another embodiment, and FIG. 6 (a) shows a state before sublimation of a pellet, and FIG. () Is a diagram showing a state after the pellet has sublimated.

FIG. 7 is an enlarged sectional view showing a safety measure temperature detecting element which is a part of a temperature control system according to still another embodiment;
FIG. 3A shows a state before the sublimation of the pellet, and FIG. 3B shows a state after the sublimation of the pellet.

FIG. 8 is a block diagram showing the principle of a temperature control system of a conventional heating device.

[Explanation of symbols]

 3 Heating Body 10 CPU (Temperature Control Means) 14 Power Supply 15 Bimetal (Temperature Sensing Element for Safety Measures) 17 Relay Signal Line 17a, 17b Contact (Temperature Sensing Element for Safety Measures) 21 Conductive Resin (Temperature Sensing Element for Safety Measures) 22 Projection (temperature detecting element for safety measures) 23 Fluororesin film (temperature detecting element for safety measures) 31 Pellet (temperature detecting element for safety measures) 32 Coil (temperature detecting element for safety measures) 41a, 41b Electrode (for safety measures) Temperature detecting element) 42 Pellet (temperature detecting element for safety measures) P Material to be heated

Claims (9)

[Claims] 1. A heating element, wherein a film is slid on a fixedly supported heating element, a heating element is brought into close contact with a surface of the film opposite to the heating element, and the heating element is moved together with the film. To apply heat energy from the heating element through the film by passing through the position, a circuit in which the heating element, the power supply, and the relay are connected in series, a power supply from the power supply to the heating element, and a relay. The temperature control means connected to the relay via the signal line and the power supply from the power supply to the heating element is stopped when a runaway occurs in which the temperature cannot be controlled and the voltage is applied to the heating element. In a heating device having a safety measure temperature detecting element, the safety measure temperature detecting element is provided on a relay signal line connecting between the relay and the temperature control means and arranged at the position of the heating element, A heating device characterized in that when a runaway is detected due to an abnormal rise in temperature of the body, a relay is opened to stop energization from the power supply to the heating body. 2. The heating device according to claim 1, wherein the safety temperature detecting element is formed directly on the heating element. 3. A temperature detecting element for safety measures, comprising: a pair of contacts provided on a heating element and connected to a relay signal line; one end fixed to one contact and the other end connected to the other contact. 2. The method according to claim 1, which comprises a contactable and separable bimetal.
Heating equipment. 4. A temperature detecting element for safety measures is made of a pair of contacts provided on a heating element and connected to a relay signal line, and a conductive resin connected between the pair of contacts. The heating device according to claim 1. 5. The heating device according to claim 4, wherein the temperature sensing element for safety measures is provided with a mountain-shaped projection protruding toward the conductive resin side on the heating body. 6. The heating device according to claim 5, wherein the temperature detecting element for safety measures has a surface of a chevron-shaped projection coated with a fluororesin. 7. A temperature detecting element for safety measures comprises a sublimable resin pellet, a coil sealed in the pellet, a coil connected to the coil and connected to a relay, and the pellet sublimates. 2. The heating device according to claim 1, further comprising an inductance detection circuit configured to cut off a relay when detecting a change in inductance when the element is deformed. 8. A temperature sensing element for safety measures is connected to a pair of electrodes, a sublimable resin pellet provided between the pair of electrodes, and connected to the electrodes and to a relay. The heating device according to claim 1, wherein the relay is set to be cut off when a change in capacitance between the electrodes when the pellet is sublimated is detected. 9. The temperature sensing element for safety measures, wherein one of the electrodes is formed by printing on a heating body.
A heating device according to claim 1.