JP2013206690A - Planar heating element and planar heating element system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive planar heating element which can eliminate moisture and vapor upon entering thereinto.SOLUTION: A moisture-permeation waterproof sheet 6 is provided to cover an internal circuit consisting of a PTC heating element 2, wiring 3, a power receiving coil 4, and a lead wire 5. The moisture-permeation waterproof sheet 6 is bonded to a substrate 1 by means of a water-impermeable sealing material 7 provided near the outer periphery of the substrate 1. The sealing material 7 is provided on the outer periphery of the substrate 1 so as to surround the internal circuit entirely. Consequently, the internal circuit is sealed liquid-tightly to the outside by means of the substrate 1, the moisture-permeation waterproof sheet 6, and the sealing material 7.

Description

  The present invention relates to a planar heating element and a planar heating element system.

  In bathrooms and washrooms, when you try to see a mirror, it often becomes cloudy and invisible. Various attempts have been made to prevent such fogging (antifogging).

  For example, Patent Document 1 discloses a technique of a planar heating element used for anti-fogging. FIG. 13A is a cross-sectional view showing this planar heating element. A heating element 102 made of a resistor film and a wiring 103 are provided on the substrate 101. The heater unit 104 is formed by these three elements. The heater unit 104 is sandwiched between two waterproof sheets 105 and sealed with a heat seal 106 formed around the heater unit 104. A hole 107 is formed in the waterproof sheet 105 on the side where the wiring 103 is provided. A cap 108 having a hole communicating with the hole 107 is provided on the waterproof sheet 105. Further, a power supply line 109 is disposed through the hole 107. The power supply line 109 is connected to the wiring 103. The power supply line 109 is covered with a waterproof coating 110. The connecting portion between the cap 108 and the waterproof sheet 105 and the connecting portion between the power supply line 109 and the cap 108 are sealed with an adhesive 111. By setting it as the above structures, the heater unit 104 containing the heat generating body 102 is hold | maintained liquid-tightly. For this reason, the heater unit 104 does not come into contact with water even when the sheet heating element is splashed with water. With the above configuration, stable operation is ensured even in an environment with a lot of water.

  FIG. 13B is a plan view showing the configuration of the heater unit 104. The wiring 103 is divided into two, each of which is formed in a comb shape. A heating element 102 is formed in a stripe shape between the comb teeth. The heating element 102 generates heat by applying a voltage to the wiring 103 and passing a current through the heating element 102. With the above configuration, the planar heating element generates heat uniformly in the plane. For this reason, if the planar heating element according to the present technology is brought into close contact with the back surface of the mirror, uniform and efficient anti-fogging can be achieved.

  Further, in Patent Document 2, instead of the waterproof sheet of Patent Document 1, chemical resistance is improved by laminating a heater unit using a multilayer film having waterproofness, moisture resistance, heat resistance, and chemical resistance. A technique for a planar heating element is disclosed.

  Patent Document 3 shows a structure using a PTC heating element (Positive Temperature Coefficient heating element) as a heating element in the same structure as Patent Document 1. The PTC heating element is a substance having a positive resistance temperature coefficient, and when the temperature reaches a predetermined temperature, the resistance rapidly increases. For this reason, the current flows at a low temperature to generate heat, and when the temperature rises to a predetermined temperature, the current stops flowing and the heat generation stops. By this operation, the temperature can be kept constant.

Japanese Patent Laid-Open No. 10-302942 Japanese Patent No. 3010550 JP-A-10-179350

  The 1st problem of patent document 1, 2 is that there exists a possibility of corrosion by water vapor | steam. In these configurations, the connecting portion is sealed with a sealing material or the like. However, since the water vapor enters even in a slight gap, it is difficult to completely shut out the water vapor. Once the water vapor enters, the water is hardly released to the outside due to the blocking structure. For this reason, there exists a possibility that a wiring and a heat generating body may be corroded with progress of time. The details of the connecting portion are not disclosed in Patent Document 3, but it is assumed that a similar structure is assumed with reference to the drawings.

  The second problem is high cost. In the conventional technique, a conductive wire for supplying electric power is connected to the heater unit through a hole in a sheet having a waterproof function. The connecting portion is sealed with a sealing material or the like. In order to form such a sealing structure, a dedicated member is required, and processing work is also required.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an inexpensive planar heating element that can eliminate water vapor even if it enters.

  In order to achieve the above object, the planar heating element of the present invention has a circuit part in which a heating resistor, a wiring, and a power receiving coil are electrically connected on an insulating and water-impermeable substrate, A seal portion is provided to surround the circuit portion, a moisture-permeable waterproof sheet is provided to cover the circuit portion, and the circuit portion is liquid-tightly sealed by the substrate, the moisture-permeable waterproof sheet, and the seal portion. ing.

  According to the present invention, even if water vapor permeates, it can be eliminated and an inexpensive sheet heating element can be configured.

It is a top view which shows the planar heating element of 1st Embodiment. It is sectional drawing which shows the planar heating element of 1st Embodiment. It is sectional drawing which shows the manufacturing method of the planar heating element of 1st Embodiment. It is a top view which shows the planar heating element of 2nd Embodiment. It is sectional drawing which shows the planar heating element system of 3rd Embodiment. It is a circuit diagram which shows the equivalent circuit of 3rd Embodiment. It is sectional drawing which shows the planar heating element system of 4th Embodiment. It is sectional drawing which shows the planar heating element system of 5th Embodiment. It is sectional drawing which shows the planar heating element system of 6th Embodiment. It is sectional drawing which shows the supporting member of the form of 7th Embodiment. It is sectional drawing which shows the planar heating element of the form of 8th Embodiment. It is sectional drawing which shows the planar heating element of the form of 9th Embodiment It is sectional drawing which shows the planar heating element of a prior art.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a partially broken plan view showing a planar heating element 1 according to a first embodiment of the present invention.

  A PTC heating element 2 is provided in a stripe shape on an impermeable and insulating substrate 1. Here, the PTC of the PTC heating element 2 is an abbreviation for Positive Temperature Coefficient, which is a substance having a positive resistance temperature coefficient. In the PTC heating element 2, the resistance increases abruptly at a predetermined temperature or higher, making it difficult for current to flow. For this reason, even if a voltage is continuously applied, heat generation stops at a predetermined temperature. By this action, the PTC heating element 2 operates to keep itself at a predetermined temperature.

  The PTC heating elements 2 are arranged on the surface of the substrate 1 so as to be arranged almost evenly. Two wirings 3 are provided in the vicinity of the outer periphery of the substrate 1. The PTC heating element 2 is connected to the wiring 3 in parallel. On top of that, a power receiving coil 4 for receiving electric power is installed in a state insulated from the PCT heating element 2 and the wiring 3. The terminal of the power receiving coil 4 and the terminal of the wiring 3 are electrically connected by the lead wire 5. Hereinafter, a circuit including the PTC heating element 2, the wiring 3, the power receiving coil 4, and the lead wire 5 is referred to as an internal circuit.

  A moisture permeable waterproof sheet 6 is provided so as to cover the internal circuit. The moisture permeable waterproof sheet 6 is bonded to the substrate 1 by a water-impermeable sealing material 7 provided in the vicinity of the outer periphery of the substrate 1. The sealing material 7 is provided on the outer peripheral portion of the substrate 1 so as to surround all the internal circuits. Therefore, the internal circuit is liquid-tightly sealed from the outside by the substrate 1, the moisture-permeable waterproof sheet 6, and the sealing material 7. Thus, in the present invention, since there is no lead wiring for connecting the internal circuit and the external circuit, there is no opening for the lead wiring in the moisture permeable waterproof sheet 6, the substrate 1, and the sealing material 7. In addition, when the board | substrate 1 and a moisture-permeable waterproof sheet are materials which can apply a heat seal, you may seal by a heat seal, without using the sealing material 7. FIG.

  On the substrate 1, an indicator 8 for displaying the power reception status and operation status of the planar heating element may be provided as an internal circuit component. In this case, the indicator 8 is connected to the wiring 3.

  In FIG. 1, the power receiving coil 4 is drawn in a donut shape having a rotation axis in the vertical direction of the substrate 1. However, for example, it may be of a coupler type having a core in a direction perpendicular thereto. The type of coil is determined according to the specifications on the power feeding side, and can take various forms.

  FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG. As shown in FIG. 2, the internal circuit disposed on the substrate 1 is liquid-tightly sealed by the substrate 1, the sealing material 7, and the moisture-permeable waterproof sheet 6. As described above, in the planar heating element according to the present embodiment, there is no wiring drawn out to the outside. For this reason, there is no hole in the moisture-permeable waterproof sheet 6, the substrate 1, and the seal portion 7, and sealing with water is easy and the reliability is high. Furthermore, processing such as drilling, positioning of wiring, waterproofing around the hole is unnecessary, and the labor of members and processing can be greatly reduced as compared with the conventional case.

  Next, a method for manufacturing the planar heating element in the present embodiment will be described. FIG. 3 is a cross-sectional view showing a method for manufacturing a planar heating element in the present embodiment. First, as shown in FIG. 3A, a pattern of a PCT heating element 2 is formed on a substrate 1. The substrate is impermeable and insulating and has heat resistance (for example, about 100 ° C.). For example, a resin such as PET, polyimide, ABS, or polycarbonate can be used. In addition, since it is desirable that the thermal conductivity is high, polyphenylene sulfide or polybutylene terephthalate having improved thermal conductivity, or those obtained by imparting thermal conductivity to the above-described resin are preferable. The PCT heating element 2 is formed by applying a raw material paste using screen printing or the like and curing it. As a material of the PTC heating element 2, a material in which carbon particles are dispersed in a resin or a material using graft carbon is suitable. Alternatively, a metal fine particle such as a nickel alloy dispersed in a resin may be used.

  Next, a pattern of wiring 3 is formed as shown in FIG. The pattern is formed by applying a paste as a raw material by screen printing or the like. Next, it is cured by heat curing or the like. The material of the wiring 3 is desirably low resistance, and a material obtained by solidifying fine particles such as Ag, Cu, Sn, and alloys thereof with a binder is preferable.

  Next, as shown in FIG. 3C, the power receiving coil 4 is installed using an adhesive, an adhesive tape, or the like. Further, the lead wire 5 is used to connect the terminal of the power receiving coil 4 to the wiring 3 by soldering or the like. The power receiving coil 4 is a wound coil, and it is desirable that parts other than the terminals are housed in an insulating package. The specification of the power receiving coil 4 is determined by matching with the power transmission side. Although not shown, it is desirable that the connection portion of the wiring is sealed with a waterproof resin such as epoxy or silicone.

  Next, as shown in FIG. 3D, the indicator 8 is installed with an adhesive, an adhesive tape, etc., and connected to the wiring 3 by soldering, wire bonding, or the like.

  Next, as shown in FIG. 3E, a pattern of the sealing material 7 is formed by dispensing or the like. The sealing material 7 is a waterproof resin, and various resins such as epoxy, silicone, urethane, and polyester can be used.

  Next, a moisture permeable waterproof sheet 6 is attached as shown in FIG. Next, the sealing material 7 is cured, and the planar heating element 1 is completed. The moisture permeable waterproof sheet 6 is a sheet having a property of passing water vapor but not water. Although various things are sold for apparel and building materials, these things are applicable also to this invention. Typical examples include high density polyethylene nonwoven fabric and polyester nonwoven fabric. If the moisture-permeable waterproof sheet 6 can be heat-sealed with respect to the substrate 1, the moisture-permeable waterproof sheet 6 and the substrate 1 may be bonded by heat sealing without using the sealing material 7.

  Next, the operation of the planar heating element of the present embodiment will be described. First, the power receiving coil 4 receives power. Then, a potential difference is generated between the two wirings 3. A current flows through the PTC heating element 2 to generate heat. Since the PTC heating elements 2 are distributed almost uniformly in the plane, the temperature of the substrate 1 also rises uniformly in the plane. Further, when the temperature of the PTC heating element 2 rises to a predetermined temperature, the resistance of the PTC heating element 2 rapidly increases and the heat generation stops. For this reason, the planar heating element operates so as to keep the temperature constant.

  Here, let us consider a case where the planar heating element is placed in an environment where there is a lot of moisture such as a bathroom or a washroom and is likely to be humid. Considering the case where water is first applied, the planar heating element is sealed in a liquid-tight manner, so that water does not enter inside. Next, consider the case of being placed in a humid environment. Since the moisture permeable waterproof sheet 6 allows water vapor to pass through, the humidity inside the planar heating element also increases as the humidity of the outside air increases. When power is supplied to the power receiving coil 4 in this state, the PTC heating element 2 generates heat. Then, the temperature inside the sheet heating element rises, and the moisture entering the inside evaporates and is released to the outside. As the temperature of the PTC heating element 2 increases, the temperature of the substrate 1 also increases. For this reason, fogging and condensation do not occur on the outer surface of the substrate 1. In this way, even when placed in a humid environment, the planar heating element of the present invention does not cause fogging or condensation on the surface. Further, the inside of the planar heating element is kept dry.

  Next, a case where a defect occurs in a part of the seal and moisture enters the planar heating element will be considered. Also in this case, due to the same action as described above, the moisture inside the planar heating element becomes water vapor and is diffused to the outside.

  By the above operation, the components such as the PTC heating element 2 and the wiring 3 are not corroded by the action of moisture. Furthermore, even if the seal is defective, moisture is eliminated and corrosion does not occur. Thus, the performance of the planar heating element is maintained even in a humid environment.

In addition, when a mirror is used as the substrate 1, the planar heating element itself becomes an antifogging mirror. Moreover, since the board | substrate 1 should just have insulation, water impermeability, and heat resistance, the technique of this Embodiment is applicable also to a tile, wallpaper, etc.
(Second Embodiment)
FIG. 4 is a plan view showing a second embodiment of the present invention. In the present embodiment, the two wirings 3 are comb-shaped and are opposed to each other. The PTC heating element 2 is formed in a stripe shape so as to connect these wirings. In this embodiment, since the heat generation points are divided more finely than in the first embodiment, the in-plane uniformity of the planar heating element temperature is improved.
(Third embodiment)
FIG. 5 is a sectional view showing a third embodiment of the present invention. The present embodiment is a planar heating element system including a power unit 9 that supplies electric power in addition to the planar heating element. The power unit 9 includes a power supply circuit 10, a power transmission coil 11, and a feeder line 12. Here, an example in which the planar heating element system is installed on the wall 13 is shown. The planar heating element is attached to the wall 13 by a support member 14. The wall 13 must be an insulator in order to perform wireless power feeding.

  As shown in FIG. 5, the power unit 9 and the planar heating element are installed facing each other with the wall 13 interposed therebetween. Moreover, it is necessary to install the power transmission coil 11 and the power reception coil 4 in the same position. When power is transmitted by the electromagnetic induction method, the frequency is preferably 10 kHz to 1 MHz. At this time, since the transmission distance is about several centimeters, the wall 13 is preferably thinner.

FIG. 6 is an equivalent circuit of the planar heating element system according to the present embodiment. First, the magnetic lines 15 generated by the power transmission coil 11 pass through the wall 13. The magnetic field lines 15 are periodically changed, and an induced current is generated in the power receiving coil 4 due to the fluctuations. In this way, electric power is supplied to the planar heating element. A frequency conversion circuit may be provided between the power receiving coil 4 and the wiring 3 in order to operate the planar heating element at a frequency lower than the power received by the planar heating element.
(Fourth embodiment)
FIG. 7 is a cross-sectional view showing a fourth embodiment of the present invention. In the present embodiment, a resonance circuit 16 connected to the power receiving coil 4 and a resonance circuit 16 connected to the power supply circuit 11 are provided. With this configuration, the power transmission circuit and the power reception circuit resonate, and power transmission / reception is performed by a magnetic resonance method. The frequency is preferably several tens of kHz to several hundreds of MHz. In the magnetic resonance method, since the transmission distance is long, a planar heating element system can be constructed even on a wall that is thicker than in the electromagnetic induction method. Further, a frequency conversion circuit may be provided as in the third embodiment.
(Fifth embodiment)
FIG. 8 is a sectional view showing a fifth embodiment. In the present embodiment, in the planar heating element system of the fourth or fifth embodiment, the antifogging object 17 is disposed in contact with the planar heating element. The antifogging object 17 is attached to the wall by a support member 14. It is desirable that the antifogging object 17 is in close contact with the substrate 1. Therefore, the adhesive layer 18 is provided in the example of FIG. In order to efficiently transmit the heat of the planar heating element, the adhesive layer 18 is preferably made of a material having high thermal conductivity. For example, a heat conductive double-sided tape is suitable. Note that the adhesive layer 18 is not essential when the wall 13 and the support member 14 are used to form a close-contact structure. Various objects such as mirrors, tiles, wallpaper, photographs, and paintings can be used as the antifogging object 17. When applied to a mirror, it is an anti-fog mirror.
(Sixth embodiment)
FIG. 9 is a perspective view showing a sixth embodiment of the present invention. The present embodiment relates to the shape of the support member 14 in the planar heating element system described in the fifth embodiment. The support member 14 is provided with a vent 19 on the side surface. This plays a role of releasing the released water vapor to the outside world when the planar heating element operates. Further, the drain port 20 may be provided at the lower portion of the support member 14. This serves to prevent water from accumulating inside the support member 14. In addition, since the drain port 20 does not need to be always open, it is good also as a structure which usually has a lid | cover.
(Seventh embodiment)
FIG. 10 is a sectional view showing a seventh embodiment of the present invention. In the present embodiment, the moisture permeable waterproof sheet 6 is attached to the vent hole 19 of the support member 14 of the sixth embodiment via the sealing material 7. By adopting this structure, the intrusion of water from the vent 19 is prevented. At the same time, water vapor can be released from the vent 19 to the outside.
(Eighth embodiment)
FIG. 11 is a cross-sectional view showing an eighth embodiment. In the present embodiment, one end of the moisture permeable waterproof sheet 6 that is an outer skin of the planar heating element is extended to the outside of the substrate 1 as a margin 6 ′ as shown in FIG. Then, when this planar heating element is attached to the support member 14, the blank 6 'is sandwiched between the support member 14 and the antifogging target portion 17 as shown in FIG. If it does in this way, it will become difficult for water, a detergent, etc. to penetrate | invade from the adhesive surface of the board | substrate 1 and the water-permeable moisture-proof sheet 6, and durability of a planar heating element will improve further.
(Ninth embodiment)
FIG. 12 is a partially broken plan view showing a ninth embodiment of the present invention. In the present embodiment, a humidity sensor / switch 21 is provided between the power receiving coil 4 and the wiring 3. The humidity sensor / switch has a function of turning on / off the circuit in accordance with the measurement result of the humidity sensor. For example, if it is set to be ON at a humidity of 50% and OFF at 30%, the inside of the sheet heating element is always kept at a humidity of 50% or less. Further, when the humidity is less than 30%, power is not consumed, so that power is saved. Further, if a microcomputer is incorporated in the humidity sensor / switch 21 or the power supply circuit 10 and the humidity sensor / switch 21 is off, setting the power supply circuit 10 to be in the sleep mode further reduces power consumption. Saved. The present embodiment is applicable to all of the first to ninth embodiments.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 PTC heat generating body 3 Wiring 4 Power receiving coil 5 Lead wire 6 Moisture permeable waterproof sheet 7 Seal material 8 Indicator 9 Electric power unit 10 Power supply circuit 11 Power transmission coil 12 Feed line 13 Wall 14 Support member 15 Magnetic field line 16 Resonant circuit 17 Antifogging object Material 18 Adhesive layer 19 Ventilation hole 20 Drainage port 21 Humidity sensor / switch 101 Substrate 102 Heating element 103 Wiring 104 Heater unit 105 Waterproof sheet 106 Heat seal 107 Hole 108 Cap 109 Power supply line 110 Waterproof coating 111 Adhesive

Claims (10)

  On the insulating and water-impermeable substrate, there is a circuit portion in which the heating resistor, the wiring, and the power receiving coil are electrically connected, and a seal portion is provided surrounding the circuit portion, and the circuit portion is A planar heating element, characterized in that a moisture permeable waterproof sheet is provided so as to cover the circuit portion in a liquid-tight manner by the substrate, the moisture permeable waterproof sheet, and the seal portion.   The planar heating element according to claim 1, wherein none of the moisture permeable waterproof sheet, the substrate, and the seal portion has an opening for wiring.   The planar heating element according to claim 1 or 2, wherein the heating resistor is a PTC (Positive Temperature Coefficient) heating element.   4. The power receiving coil according to claim 1, wherein the power receiving coil generates electric power due to a change in a magnetic field due to an action of an external environment, and the heating element generates heat by the electric power. 5. Planar heating element.   5. The planar shape according to claim 1, wherein the heating resistors are distributed substantially evenly on the substrate surface in a stripe shape or a dot shape. 6. Heating element.   The planar heating element includes a humidity sensor and a switch for turning on / off a circuit in accordance with an output of the humidity sensor between the power receiving coil and the resistance heating element. The planar heating element according to any one of claims 1 to 5.   The switch is turned on when the output of the humidity sensor becomes equal to or higher than a predetermined first predetermined value, and the output of the previous humidity sensor is lower than the predetermined first predetermined value. The planar heating element according to claim 6, wherein the switch is turned off when it becomes less than a predetermined value.   The planar heating element according to any one of claims 4 to 7 and a power unit including a power transmission coil that generates a magnetic field outside, and by the action of the magnetic field generated by the power transmission coil, A planar heating element system, wherein electric power is generated in the power receiving coil, and the planar heating element generates heat by the electric power.   The planar heating element system according to claim 8, wherein the planar heating element is attached so that a planar object that should be prevented from fogging is in close contact with the planar heating element.   The planar heating element system according to claim 9, wherein the planar object is a mirror.

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