JP2006278261A - Heater, heating device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve safety by preventing breakage of a heater until other safety element such as a thermal fuse functions by extending time until heating resistors of a heater are broken or an insulating substrate is cracked due to failure of a temperature control. <P>SOLUTION: The heating resistors 12, 13 are formed from a conductive component consisting essentially of silver/palladium in parallel with a longitudinal direction on a long tabular insulating substrate 11 formed from a heat-resistant insulating material. The heating resistors 12, 13 connected in series are provided with power from electrodes 14, 15. An overcoat layer 17 is formed on the insulating substrate 11 in which at least electrodes 14, 15 are left non-coated. A slit 18 without the overcoat layer 17 is formed in the whole area between the heating resistors 12, 13 or a part where electric potential difference between the heating resistors 12, 13 is high. The slit 18 extends the time until the heating resistors 12, 13 of the heater 100 are broken or the insulating substrate 11 is cracked due to the failure of the temperature control for suppressing breakage of the heater 100 until other safety functions work to improve safety. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thin heater used in information equipment, home appliances, manufacturing facilities, and the like, a heating device such as a printer, a copier, a facsimile machine, and a rewritable paper mounted with the heater, and an image processing apparatus using the heating device.

In the conventional heater, when a predetermined temperature is reached, at least part of the resistor pattern that generates heat, when the heating resistor pattern is configured, a blocking portion is formed that reacts with a component to become an insulator and cuts off current. . (For example, Patent Document 1)
JP 2002-359059 A

  In the technique of the above-mentioned Patent Document 1, the overcoat layer on the blocking portion formed on the heating resistor has a blocking portion, so that unevenness occurs, and a constant temperature distribution of the heating resistor can be obtained. There is a problem that the fixing performance is deteriorated.

  An object of the present invention is to provide a heater that contributes to safety when the temperature of the heater rises abnormally due to a failure in temperature control of the heating device for fixing, a heating device using the heater, and the heating device An object of the present invention is to provide an image forming apparatus using the above.

  In order to solve the above-described problems, a heater according to the present invention includes a long flat insulating substrate formed of a heat-resistant and insulating material, and silver and palladium mainly in parallel with the longitudinal direction on the insulating substrate. A first and second heating resistor formed in a thick film by a conductive component, an electrode for supplying power in a state of being connected in series to the first and second heating resistors, and leaving at least the electrode The overcoat layer formed on the insulating substrate and the overcoat layer are applied to the entire region between the first and second heating resistors or a portion where the potential difference between the first and second heating resistors is high. It was characterized by comprising a slit formed without.

  According to this invention, it is possible to lengthen the time until the heating resistor of the heater is broken or the insulating substrate is cracked due to the failure of the temperature control, and the heater is prevented from being broken until another safety device such as a thermal fuse functions. This makes it possible to improve safety.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram for explaining an embodiment of the heater of the present invention, FIG. 2 is an enlarged sectional view taken along lines aa ′ and bb ′ of FIG. 1, and FIG. This is the back surface of 1.

In FIG. 1, 11 is an insulating substrate such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), and 12 and 13 are parallel to the longitudinal direction of the insulating substrate 11, and the conductive component is silver / palladium ( Thick film printing is performed using a resistor paste composed of Ag / Pd) or the like. Thereafter, the heating resistor is formed by firing at about 850 ° C. Further, 14 and 15 are thick films using a conductive paste on the insulating substrate 11 whose conductive component is composed of silver (Ag), silver / platinum (Ag / Pt), silver / palladium (Ag / Pd), or the like. Print. Thereafter, the electrode is supplied with electric power formed by firing. A part of the electrode 14 is formed in a multilayered state at one end of the heating resistor 12 and is electrically connected. The electrode 15 is partially connected to one end of the heating resistor 13 in a multilayer state and is electrically connected. 16 is a connection conductor in which the other ends and a part of each of the heating resistors 12 and 13 are multilayered and formed on the insulating substrate 11 by thick film printing using a conductive paste, and the heating resistors 12 and 13 are electrically connected. It is.

Reference numeral 17 denotes an overcoat layer using a thick film printing method formed by applying and baking a glass paste covering the heating resistors 12 and 13 and the connection conductor 16 thereto. The overcoat layer 17 is formed by adding lead-free amorphous SiO, borosilicate glass mainly containing B ₂ O ₃ and alumina having higher thermal conductivity than glass.

  The overcoat layer 17 includes an overcoat layer on the insulating substrate 11 between the heating resistors 12 and 13 as shown in FIG. 2 in which the cross section taken along the lines aa ′ and bb ′ in FIG. The slit 18 which does not give 17 is formed. The slit 18 is formed over the entire area in the longitudinal direction of the heating resistors 12 and 13.

  When electric power is supplied to the electrodes 13 and 15 in the heater 100, current flows through the heating resistors 12 and 13, respectively, and the heating resistors 12 and 13 each exhibit a substantially uniform heating temperature distribution in the longitudinal direction.

  Next, the back surface side of the insulating substrate 11 will be described with reference to FIG. 3 showing the back surface of FIG. In FIG. 3, reference numerals 19 and 20 denote terminal portions, which are formed simultaneously by the same method as the electrodes 14 and 15. One end of a pair of wiring conductors 21 and 22 made of a material mainly composed of silver, palladium (Ag / Pd) or the like is coupled to the terminal portions 19 and 20, respectively. The other end of the wiring conductor 21 is connected to one electrode of the thermistor 23 fixed to the insulating substrate 11, and the other end of the wiring conductor 22 is connected to the other electrode of the thermistor 23.

  Here, the heater 100 having the above-described configuration is energized by a circuit configuration shown in FIG. That is, when the commercial power supply 41 is energized to the electrodes 14 and 15 of the heater 100 via the solid state relay 43 connected to the control terminal of the temperature control circuit 42, current is supplied to the heating resistors 12 and 13 connected in series. It flows and generates heat. The temperature of the insulating substrate 11 also rises due to heat generated by the heating resistors 12 and 13. This heat is transmitted to the temperature sensing part of the thermistor 23 attached to the back side of the insulating substrate 11 and changes the resistance value of the temperature sensing part. A change in the resistance value of the thermistor 23 is input to the temperature control circuit 42 to determine whether or not the temperature is at a set temperature of 250 ° C., for example. When the temperature is lower than the set temperature, an ON signal is output to the solid state relay 43, and when the temperature is higher than the set temperature, an OFF signal is output to the solid state relay 43.

  In this manner, the temperature of the heating resistors 12 and 13 is adjusted by controlling the power applied to the heating resistors 12 and 13. Although the temperature control circuit 42 has been described with respect to the on / off control of the solid state relay 43, other temperature adjustments such as a pulse width modulation control method may be used.

  By the way, when the temperature control shown in FIG. 4 cannot be performed due to the damage of the thermistor 23 or the like, the temperature of the heating resistors 12 and 13 continues to rise. When the temperature exceeds the temperature at which the heat generating resistors 12 and 13 are fired, for example, 850 ° C., the silver / palladium alloy of the heat generating resistors 12 and 13 is melted with the dissolution of the overcoat layer 17. The melting heat generating resistors 12 and 13 are short-circuited.

  However, even when the overcoat layer 17 and the silver / palladium alloy are melted above 850 ° C., the formation of the slit 18 melts the overcoat layer 17 so that the overcoat layer 17 fills the slit 18 and the heating resistor It takes time until 12 and 13 are short-circuited. It is possible to prevent the heater 100 from being damaged and improve safety until another safety device such as a thermal fuse functions within the earned time.

  In this embodiment, since the slits 18 are formed in the overcoat layer 17 over the entire length of the heating resistors 12 and 13, a failure occurs in the function of controlling the heater 100 to a predetermined temperature. Even when the temperature rises at which the bodies 12, 13 and the overcoat layer 17 are dissolved, it is possible to earn time for the operation of other safety devices, which contributes to the improvement of safety.

  FIG. 5 is a configuration diagram of another embodiment of the heater of the present invention, and will be described together with a cross-sectional view of FIG. 6 in which c-c ′ and d-d ′ lines of FIG. 5 are enlarged. The same components as those in the above embodiment are given the same reference numerals, and different portions will be described here.

  In this embodiment, a slit 181 is formed only between the heating resistors 12 and 13 near the electrodes 14 and 15. That is, there is no slit in the c-c ′ cross section at a position away from the electrodes 14 and 15, whereas the slit 18 is formed in the d-d ′ cross section at a position close to the electrodes 14 and 15. The thermistor 23 in this case is attached in a state where it is pressure-bonded by using a spring on the overcoat layer 17 where the slit 181 is not formed, as shown in the sectional view of FIG.

  Further, a sliding portion 61 such as glass or polyimide resin is formed on the insulating substrate 11 on the opposite side where the heating resistors 12 and 13 are formed. A fixing film of a heating device to be described later is slid on the sliding portion 61.

  For example, when 200V is supplied to the electrodes 14 and 15, the potential difference between the heating resistors 12 and 13 near the electrodes 14 and 15 is about 200V, but the potential difference gradually disappears as the distance from the heating resistors 12 and 13 increases. The potential difference near the connecting conductor 16 is close to zero.

  Therefore, if at least the slit 181 is formed on the side close to the electrodes 14 and 15 having a large potential difference, the heater 100 temperature rises due to failure of temperature control, and the electrodes 14 and 15 and the overcoat layer 17 are dissolved. It is possible to lengthen the time until 100 is damaged or the insulating substrate 11 is cracked.

  By the way, when the heat generated from the heating resistors 12 and 13 is taken from the opposite side of the insulating substrate 11, the thermistor 23 is attached to the overcoat layer 17 side in order to suppress the influence of the heat generation distribution by the thermistor 23. It is necessary to. If the thermistor 23 is disposed on the slit 181, reliable temperature detection cannot be performed due to the influence of the slit 181.

  Therefore, the slit 181 is formed in the portion affected by the potential difference, the slit 181 is not formed in the portion where the potential difference is small or small, and the thermistor 23 is disposed in the portion, thereby reliably eliminating the potential difference problem. In addition, temperature can be detected.

  Also in this embodiment, when the heater 100 rises to an abnormal temperature, the heater 100 is lengthened until the heater 100 breaks or the insulating substrate breaks, and the heater is heated until another safety element such as a thermal fuse functions. It is possible to prevent damage to 100 and improve safety.

  Next, an embodiment of the heating device according to the present invention will be described with reference to FIG. 7 when the heater described above is mounted on the heating device 200 for fixing. The heater 100 in the figure is the same as in FIGS. 1 to 3, and the same parts are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 7, reference numeral 201 denotes a pressure roller that is rotated by a rotating shaft 202, and a heat-resistant elastic material such as a silicone rubber layer 203 is fitted on the surface thereof. The heater 100 is juxtaposed with the rotating shaft 202 of the pressure roller 201 and attached to a base (not shown).

  Around the heater 100, an endless roll-shaped fixing film 204 made of a heat-resistant sheet such as a polyimide resin is circulated so as to be circulated, and an over-layer just above the insulating substrate 11 via the heating resistors 12 and 13 is provided. The surface of the coat layer 17 is in elastic contact with the silicone rubber layer 203 of the pressure roller 201 through the fixing film 204.

  In the heating device 200, the heater 100 is energized through a connector (not shown) in which a phosphor bronze plate or the like in contact with the electrodes 14, 15 is given a silver plated elasticity. By this energization, the toner image T1 is first transferred between the surface of the fixing film 204 provided on the overcoat layer 17 of the heat generating resistors 12 and 13 and the silicone rubber layer 203 via the fixing film 204. And at least its surface part greatly exceeds the melting point and is completely softened and melted. Thereafter, on the paper discharge side of the pressure roller 201, the copy paper P is separated from the heater 100, the toner image T2 is naturally radiated and cooled and solidified again, and the fixing film 204 is also separated from the copy paper P.

  As described above, the toner image T1 is once completely softened and melted and then cooled again on the paper discharge side of the pressure roller 201, so that the condensing force of the toner image T2 is very large.

  In this embodiment, even if an abnormal temperature rise occurs due to the temperature control of the heater 100, the time until the heater 100 is damaged or the insulating substrate 11 is cracked can be given by the action of the slit 18. During this time, it is possible to improve the safety of the heating device 200 by preventing the thick film printing heater from being damaged until another safety element such as a temperature fuse on the heating device 200 side functions.

  Next, with reference to FIG. 8, an image forming apparatus according to the present invention will be described, taking as an example a copying machine equipped with a heating device using a heater according to the present invention. In the figure, the part of the heating device 200 is the same as described above, and the same reference numerals are given to the same parts, and the description thereof is omitted.

  In FIG. 8, 301 is a casing of the copying machine 300, 302 is a document placing table made of a transparent member such as glass provided on the upper surface of the casing 301, and scans the document P1 by reciprocating in the arrow Y direction.

  An illuminating device 302 including a light irradiation lamp and a reflecting mirror is provided in the upper direction in the housing 301, and a reflected light source from the document P1 irradiated by the illuminating device 302 is a short focus small diameter imaging element. A slit exposure is performed on the photosensitive drum 304 by the array 303. The photosensitive drum 304 rotates in the direction of the arrow.

  Reference numeral 305 denotes a charger that uniformly charges, for example, a photosensitive drum 304 coated with a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. An electrostatic image subjected to image exposure by the imaging element array 303 is formed on the photosensitive drum 304 charged by the charger 305. This electrostatic image is visualized using toner made of a resin that softens and melts when heated by the developing device 306.

  The copy paper P stored in the cassette 307 is rotated by a pair of conveying rollers 309 that are rotated in pressure contact with each other in synchronization with the feeding roller 308 and the image on the photosensitive drum 304. Sent to the top. The toner image formed on the photosensitive drum 304 is transferred onto the copy paper P by the transfer discharger 310.

  Thereafter, the paper P that is separated from the photosensitive drum 304 is guided to the heating device 200 by the conveyance guide 311 and subjected to a heat fixing process, and then discharged into the tray 312. After the toner image is transferred, residual toner on the photosensitive drum 304 is removed using a cleaner 313.

  The heating device 200 has an effective length according to the width (length) of the maximum size paper that can be copied by the copying machine 300 in the direction orthogonal to the moving direction of the copy paper P, that is, the width (length) of the maximum size paper. The pressure roller 201 of the heater 100 is provided by extending the long heating resistors 12 and 13.

  Then, the unfixed toner image T1 on the paper P sent between the heater 100 and the pressure roller 201 is melted by receiving heat from the heating resistors 12 and 13, and characters, alphanumeric characters, Copy images such as symbols and drawings are displayed.

  In this embodiment, it is possible to realize the copying machine 300 using the heating device 200 by the good heater 100 that is improved in safety against abnormal heat generation.

  The present invention is not limited to the embodiment described above. For example, the overcoat layer material cannot be specified because it needs to be changed depending on the material of the opposing fixing film and other conditions. However, when the fixing film is a resin, the overcoat layer is an overcoat layer when glass or the fixing film is a metal. It is desirable to combine resins. As this resin, polyamide (PA), polyacetal (POM), polytetrafluoroethylene (PTFE), polyphenylene sulfide, elastomer, polyolefin, fluorine, etc., which are generally considered to be excellent in slidability, are used. Conceivable. Basically, any of them may be used, but imides such as PI (polyimide) and PAI (polyamideimide), which are heat-resistant and elastic, are preferable, but if the hardness is too low, the resin coating will be scraped off. Therefore, for example, a hardness of 3H or more is necessary.

  The thermistor 23 in the embodiment described with reference to FIGS. 1 to 3 is on the insulating substrate 11 opposite to the heating resistors 12 and 13, but is disposed on the overcoat layer 17 as shown in FIG. May be. In this case, the position where the thermistor 23 is attached is a position away from the electrodes 14 and 15, and as described in the other embodiments, the portion where the thermistor 23 is disposed is buried to suppress the influence of temperature detection by the slit 18. May be.

  Furthermore, the fixing heater is used for fixing an image forming apparatus such as a copying machine, but is not limited to this, and is not limited to a household electrical product, a precision device for business use or experiment, a device for chemical reaction, etc. It can also be used as a heat source for heating and heat retention.

The block diagram for demonstrating one Embodiment of the heater of this invention. Sectional drawing which expanded and showed each the a-a 'and b-b' line | wire of FIG. The back view of FIG. The circuit block diagram for demonstrating the temperature adjustment used for FIG. The block diagram for demonstrating other embodiment of the heater of this invention. Sectional drawing which expanded and each showed the c-c 'and d-d' line | wire of FIG. Explanatory drawing for demonstrating one Embodiment at the time of using the heater of this invention for the heating apparatus for fixing. Explanatory drawing for demonstrating one Embodiment at the time of using the heating apparatus of this invention for an image forming apparatus.

Explanation of symbols

11 Insulating substrate 12, 13 Heating resistor 14, 15 Electrode 16 Connection conductor 17 Overcoat layer 18, 181 Slit 100 Heater 200 Heating device 300 Copying machine

Claims (3)

A long flat insulating substrate formed of a heat-resistant and insulating material;
First and second heating resistors formed in a thick film by a conductive component mainly composed of silver and palladium in parallel with the longitudinal direction on the insulating substrate;
An electrode for supplying power in a state connected in series to the first and second heating resistors;
An overcoat layer applied on the insulating substrate leaving at least the electrodes;
And a slit formed without applying the overcoat layer to the entire region between the first and second heating resistors or a portion having a high potential difference between the first and second heating resistors. And heater. A heating roller;
The fixing heater according to claim 1, wherein a heating resistor disposed opposite to the heating roller is pressed against the heating roller.
A heating apparatus comprising a fixing film movably provided between the fixing heater and the heating roller. Forming means for attaching a toner to an electrostatic latent image formed on a medium and transferring the toner to a sheet to form a predetermined image;
4. A fixing device according to claim 3, wherein the toner is fixed by passing a sheet on which an image is formed while being pressed against the fixing heater through a fixing film by a pressure roller. Image forming apparatus.

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