Planar heating element

Abstract

To provide a planar heating element capable of improving efficiency of temperature control.SOLUTION: A planar heating element comprises: an insulation sheet including a first face and a second face which is a rear face thereof; a PTC (Positive Temperature Coefficient) element provided on the first face; an electrode provided on the second face; and a heat conduction member provided on the second face. The PTC element is provided on the first face so as to enclose an outer peripheral portion of the first face and connected in series with the electrode. The electrode is provided on the second face in such a manner that a portion thereof is overlapped with a position of the PTC element on the first face. The heat conduction member is provided on the second face so as to enclose an outer peripheral portion of the second face and to be in contact with a portion of the electrode.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a planar heating element.

Background Art

[0002] Conventionally, a planar heating element in which an electrode and a PTC (Positive Temperature Coefficient) element are provided on the surface of a planar substrate has been known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional planar heating element, there is room for improvement in terms of the efficiency of temperature control.

[0005] An object of one aspect of the present disclosure is to provide a planar heating element capable of improving the efficiency of temperature control.

Means for Solving the Problems

[0006] A planar heating element according to one aspect of the present disclosure includes an insulating sheet having a first surface and a second surface which is the back surface thereof, a PTC (Positive Temperature Coefficient) element provided on the first surface, an electrode provided on the second surface, and a heat conduction member provided on the second surface, the PTC element is provided on the first surface so as to surround the outer peripheral portion of the first surface and is connected in series with the electrode, the electrode is provided on the second surface such that a part thereof overlaps with the position of the PTC element on the first surface, and the heat conduction member is provided on the second surface so as to surround the outer peripheral portion of the second surface and contact a part of the electrode. [Effects of the Invention]

[0007] According to this disclosure, the efficiency of temperature control can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] Front view showing the first surface of a planar heating element according to Embodiment 1 of this disclosure [Figure 2] Front view showing the second surface of the planar heating element according to Embodiment 1 of this disclosure [Figure 3] Front view showing the second surface superimposed on the first surface of the planar heating element according to Embodiment 1 of this disclosure. [Figure 4] Front view showing the second surface of the planar heating element according to Embodiment 2 of this disclosure [Figure 5] Front view showing the second surface superimposed on the first surface of the planar heating element according to Embodiment 2 of this disclosure. [Figure 6] Front view showing the second surface of the planar heating element according to Embodiment 3 of this disclosure [Figure 7] Front view showing the second surface superimposed on the first surface of the planar heating element according to Embodiment 3 of this disclosure. [Modes for carrying out the invention]

[0009] The planar heating element 100 according to Embodiments 1 to 3 of this disclosure will be described below with reference to Figures 1 to 7. Common components in each figure are denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0010] (Embodiment 1) The planar heating element 100 according to Embodiment 1 will be described with reference to Figures 1 to 3. Figure 1 is a front view showing the first surface of the planar heating element 100 according to Embodiment 1. Figure 2 is a front view showing the second surface of the planar heating element 100 according to Embodiment 1. Figure 3 is a front view showing the second surface shown in Figure 2 superimposed on the first surface shown in Figure 1.

[0011] As shown in FIGS. 1 to 3, the planar heating element 100 has an insulating sheet 1 as a base material having electrical insulation. The insulating sheet 1 is a planar member and has a first surface and a second surface which is the back surface thereof.

[0012] Also, as shown in FIGS. 1 to 3, the planar heating element 100 has electrodes 2 to 4, a PTC (Positive Temperature Coefficient) element 5, terminals 6 to 9, and an electrode 11.

[0013] As shown in FIG. 1, on the first surface of the planar heating element 100 (specifically, the first surface of the insulating sheet 1), the electrodes 2 to 4 and a PTC element (which may also be referred to as a PTC resistor) 5 are provided.

[0014] On the other hand, as shown in FIG. 2, on the second surface of the planar heating element 100 (specifically, the second surface of the insulating sheet 1), the electrode 11 and a heat conduction member 20 are provided.

[0015] The PTC element 5 is an element having a self-temperature control function (a function in which when a predetermined temperature is reached, the current is limited by an increase in the resistance value). The PTC element 5 is provided so as to surround the outer peripheral portion of the insulating sheet 1 (in other words, along the outer periphery of the insulating sheet 1) as shown in FIGS. 1 and 3.

[0016] The electrodes 2 to 4 are provided so as to be separated from each other as shown in FIGS. 1 and 3. Thereby, electrical insulation is ensured in the electrodes 2 to 4.

[0017] Also, as shown in FIGS. 1 and 3, the terminals 6, terminals 7 to 8, and terminal 9 are provided on the electrodes 2 to 4, respectively. These terminals 6 to 9 are conductive members for making the first surface side and the second surface side of the insulating sheet 1 conductive.

[0018] The terminal 6 is provided so as to penetrate the electrode 2 and the insulating sheet 1. A lead wire (not shown) is connected to the first surface side of the terminal 6.

[0019] Terminals 7 and 8 are respectively provided through the electrode 3 and the insulating sheet 1. As shown in FIGS. 2 and 3, terminal 8 is electrically connected to electrode 11 on the second surface side. A lead wire (not shown) is connected to the first surface side of terminal 7.

[0020] Terminal 9 is provided through the electrode 4 and the insulating sheet 1. As shown in FIGS. 2 and 3, terminal 9 is electrically connected to electrode 11 on the second surface side.

[0021] Although not shown in the drawings, electrodes 2 and 4 each have a comb-tooth shaped portion between the PTC element 5 and the insulating sheet 1. The contour shape of the comb-tooth shaped portion is substantially the same as the shape of the PTC element 5 shown in FIG. 1. That is, the comb-tooth shaped portion is provided so as to surround the outer peripheral portion of the insulating sheet 1 (in other words, along the outer periphery of the insulating sheet 1).

[0022] Specifically, the comb-tooth shaped portion of electrode 2 includes a plurality of comb teeth arranged in parallel and spaced apart from each other, and they are provided so as to surround the outer peripheral portion of the insulating sheet 1. And the tips of the plurality of comb teeth are arranged in the vicinity thereof without contacting electrode 4. Similarly, the comb-tooth shaped portion of electrode 4 includes a plurality of comb teeth arranged in parallel and spaced apart from each other, and they are provided so as to surround the outer peripheral portion of the insulating sheet 1. And the tips of the plurality of comb teeth are arranged in the vicinity thereof without contacting electrode 2. Also, the plurality of comb teeth in electrode 2 and the plurality of comb teeth in electrode 4 are combined so as not to contact each other. The PTC element 5 is provided on the comb-tooth shaped portions of electrodes 2 and 4 combined with each other in this way.

[0023] Electrode 11 is a linear electrode. As shown in FIGS. 2 and 3, one end of electrode 11 is connected to terminal 8, and the other end of electrode 11 is connected to terminal 9. Also, most of electrode 11 is in a zigzag shape.

[0024] Furthermore, as shown in Figure 3, the electrode 11 is provided on the second surface such that a portion of it overlaps with the position of the PTC element 5 provided on the first surface. Also, as shown in Figure 3, the electrode 11 is provided on the second surface such that most of it is located inside the PTC element 5 provided on the first surface (the region surrounded by the PTC element 5).

[0025] The electrode 11 may be, for example, a metal wire with a pre-formed pattern placed on the insulating sheet 1, or a metal layer placed on the insulating sheet 11 may be patterned by etching, cutting, or the like.

[0026] The heat conductive member 20 is a member that possesses thermal conductivity. An example of the heat conductive member 20 is a heat conductive tape made of metal foil (for example, aluminum) (the same applies to embodiments 2 and 3 described later).

[0027] As shown in Figure 2, the heat conductive member 20 is rectangular in shape and is provided so as to surround the outer periphery of the insulating sheet 1 (in other words, along the outer periphery of the insulating sheet 1). Therefore, when the insulating sheet 1 is viewed from above, the position of the heat conductive member 20 on the second surface and the position of the PTC element 5 on the first surface coincide.

[0028] Furthermore, the heat conductive member 20 is provided on the electrode 11 on the second surface. As shown in Figure 2, the heat conductive member 20 is in contact with a portion of the electrode 11. More precisely, it is in contact with a portion of the electrode 11 via an insulating material such as double-sided tape.

[0029] Note that in Figure 3, the heat conductive member 20 is omitted from the illustration for improved visibility.

[0030] Next, we will explain the current flow in the planar heating element 100 configured as described above. Here, we will explain using the example where the input terminal for the current is terminal 7 and the output terminal for the current is terminal 6.

[0031] The current flowing into terminal 7 from the lead wire (not shown) connected to the first side of terminal 7 reaches terminal 8 on the first side via electrode 3.

[0032] Next, the current that passes through terminal 8 flows through electrode 11 on the second surface and reaches terminal 9. This current conduction causes electrode 11 to heat up.

[0033] Next, the current passing through terminal 9 flows sequentially through electrode 4, PTC element 5, and electrode 2 on the first surface, and reaches terminal 6. This energization causes the PTC element 5 to operate as a heating element that controls its own temperature. The current then flows into the lead wire (not shown) connected to the first surface side of terminal 6.

[0034] From this current flow, it can be said that the PTC element 5 is connected in series with the electrode 11.

[0035] Alternatively, the input and output terminals for the current may be designated as terminals 6 and 7, respectively. In that case, the current will flow in the reverse order of the sequence described above.

[0036] (Embodiment 2) The planar heating element 100 according to Embodiment 2 will be described with reference to Figures 4 and 5. Figure 4 is a front view showing the second surface of the planar heating element 100 according to Embodiment 2. Figure 5 is a front view showing the second surface shown in Figure 4 superimposed on the first surface shown in Figure 1.

[0037] The first surface of the planar heating element 100 according to Embodiment 2 is the same as that of Embodiment 1 (see Figure 1), so its description is omitted here.

[0038] As shown in Figure 4, the second surface of the planar heating element 100 is provided with electrodes 12 including strip-shaped electrodes 12a, 12b and a linear electrode 12c, and a heat conductive member 20.

[0039] One end of the strip-shaped electrode 12a is connected to terminal 8. Additionally, a portion of the strip-shaped electrode 12a is provided along the right-hand edge of the second surface.

[0040] One end of the strip-shaped electrode 12b is connected to terminal 9. Additionally, a portion of the strip-shaped electrode 12b is provided along the left-hand edge of the second surface.

[0041] The linear electrode 12c includes three sections formed in a zigzag pattern (hereinafter referred to as the zigzag section). At each zigzag section, one end is connected to the strip electrode 12a and the other end is connected to the strip electrode 12b.

[0042] The electrode 12 is formed, for example, by printing (e.g., screen printing) a conductive paste (e.g., copper paste or silver paste) onto the insulating sheet 1 to create a pattern, but is not limited to this, and may be formed by other methods.

[0043] Furthermore, as shown in Figure 5, the electrode 12 is provided on the second surface such that a portion of it (for example, a portion of the linear electrode 12c) overlaps with the position of the PTC element 5 provided on the first surface. Also, as shown in Figure 5, the electrode 12 is provided on the second surface such that most of it (for example, most of the linear electrode 12c) is located inside the PTC element 5 provided on the first surface (the region surrounded by the PTC element 5).

[0044] As shown in Figure 4, the heat conductive member 20 is in the shape of a rectangular ring and is provided so as to surround the outer periphery of the insulating sheet 1 (in other words, along the outer periphery of the insulating sheet 1). Therefore, when the insulating sheet 1 is viewed from above, the position of the heat conductive member 20 on the second surface and the position of the PTC element 5 on the first surface coincide.

[0045] Furthermore, the heat conductive member 20 is provided on the electrode 12 on the second surface. As shown in Figure 4, the heat conductive member 20 is in contact with a portion of the electrode 12 (specifically, all of the strip electrodes 12a and 12b and a portion of the linear electrode 12c).

[0046] Note that in Figure 5, the heat conductive member 20 is omitted from the illustration for improved visibility.

[0047] Next, we will explain the current flow in the planar heating element 100 configured as described above. Here, we will explain using the example where the input terminal for the current is terminal 7 and the output terminal for the current is terminal 6.

[0048] The current flowing into terminal 7 from the lead wire (not shown) connected to the first side of terminal 7 reaches terminal 8 on the first side via electrode 3.

[0049] Next, the current passing through terminal 8 flows sequentially through electrodes 12a, 12c, and 12b on the second surface, reaching terminal 9. This current conduction causes electrode 12 to heat up.

[0050] Next, the current passing through terminal 9 flows sequentially through electrode 4, PTC element 5, and electrode 2 on the first surface, and reaches terminal 6. This energization causes the PTC element 5 to operate as a heating element that controls its own temperature. The current then flows into the lead wire (not shown) connected to the first surface side of terminal 6.

[0051] From this current flow, it can be said that the PTC element 5 is connected in series with the electrode 12.

[0052] Alternatively, the input and output terminals for the current may be designated as terminals 6 and 7, respectively. In that case, the current will flow in the reverse order of the sequence described above.

[0053] (Embodiment 3) The planar heating element 100 according to Embodiment 3 will be described with reference to Figures 6 and 7. Figure 6 is a front view showing the second surface of the planar heating element 100 according to Embodiment 3. Figure 7 is a front view showing the second surface shown in Figure 6 superimposed on the first surface shown in Figure 1.

[0054] The first surface of the planar heating element 100 according to Embodiment 3 is the same as that of Embodiment 1 (see Figure 1), so its description is omitted here. In this embodiment, since a transparent electrode 13 is used, it is preferable to use a transparent material for the insulating sheet 1 as well.

[0055] As shown in Figure 6, the second surface of the planar heating element 100 is provided with a transparent electrode 13, strip electrodes 14 and 15, and a heat conductive member 20.

[0056] The transparent electrode 13 is provided on almost the entire second surface of the insulating sheet 1 (excluding the lower part of the second surface). Examples of the transparent electrode 13 include, but are not limited to, an AG (silver) film or an ITO (indium tin oxide) film.

[0057] One end of the strip-shaped electrode 14 is connected to the terminal 8. Additionally, a portion of the strip-shaped electrode 14 is provided along the right-hand edge of the second surface and in contact with the transparent electrode 13.

[0058] One end of the strip-shaped electrode 15 is connected to the terminal 9. Additionally, a portion of the strip-shaped electrode 15 is provided along the left edge of the second surface and in contact with the transparent electrode 13.

[0059] Furthermore, since the transparent electrode 13 is provided on almost the entire second surface, as shown in Figure 7, a portion of the transparent electrode 13 overlaps with the position of the PTC element 5 provided on the first surface. Also, as shown in Figure 7, the transparent electrode 13 is provided on the second surface such that most of it is located inside the PTC element 5 provided on the first surface (the region surrounded by the PTC element 5).

[0060] As shown in Figure 6, the heat conductive member 20 is in the shape of a rectangular ring and is provided so as to surround the outer periphery of the insulating sheet 1 (in other words, along the outer periphery of the insulating sheet 1). Therefore, when the insulating sheet 1 is viewed from above, the position of the heat conductive member 20 on the second surface and the position of the PTC element 5 on the first surface coincide.

[0061] Furthermore, the heat conductive member 20 is provided on the electrode 13 on the second surface. As shown in Figure 6, the heat conductive member 20 is in contact with a portion of the electrode 13 (specifically, the left and right ends of the transparent electrode 13).

[0062] Note that in Figure 7, the heat conductive member 20 is omitted from the illustration for improved visibility.

[0063] Next, we will explain the current flow in the planar heating element 100 configured as described above. Here, we will explain using the example where the input terminal for the current is terminal 7 and the output terminal for the current is terminal 6.

[0064] The current flowing into terminal 7 from the lead wire (not shown) connected to the first side of terminal 7 reaches terminal 8 on the first side via electrode 3.

[0065] Next, the current passing through terminal 8 flows sequentially through electrode 14, transparent electrode 13, and electrode 15 on the second surface, and reaches terminal 9. This current flow causes the transparent electrode 13 to heat up.

[0066] Next, the current passing through terminal 9 flows sequentially through electrode 4, PTC element 5, and electrode 2 on the first surface, and reaches terminal 6. This energization causes the PTC element 5 to operate as a heating element that controls its own temperature. The current then flows into the lead wire (not shown) connected to the first surface side of terminal 6.

[0067] From this current flow, it can be said that the PTC element 5 is connected in series with the transparent electrode 13 and electrodes 14 and 15.

[0068] Alternatively, the input and output terminals for the current may be designated as terminals 6 and 7, respectively. In that case, the current will flow in the reverse order of the sequence described above.

[0069] The planar heating element 100 according to Embodiment 3 is attached, for example, to a transparent member of an optical device (for example, a protective glass provided in front of an image sensor) by double-sided tape. Examples of optical devices include, but are not limited to, an in-vehicle camera that detects the surrounding conditions of a vehicle (which may also be called a collision avoidance camera), a surveillance camera installed on a building, etc., and an in-vehicle electronic door mirror. The planar heating element 100 may also be attached to a transparent member other than an optical device (for example, a vehicle's glass window, etc.).

[0070] The planar heating element 100 according to Embodiments 1 to 3 has been described above. The effects and advantages of the planar heating element 100 according to Embodiments 1 to 3 are summarized below.

[0071] The planar heating element 100 according to this embodiment comprises an insulating sheet 1 having a first surface and a second surface which is the back surface thereof, a PTC element 5 provided on the first surface, an electrode 11 (electrode 12 in Embodiment 2, transparent electrode 13 in Embodiment 3; the same applies hereinafter) provided on the second surface, and a heat conductive member 20 provided on the second surface. The PTC element 5 is provided on the first surface so as to surround the outer periphery of the first surface and is connected in series with the electrode 11. The electrode 11 is provided on the second surface so as to overlap a portion of the position of the PTC element 5 on the first surface, and the heat conductive member 20 is provided on the second surface so as to surround the outer periphery of the second surface and be in contact with a portion of the electrode 11.

[0072] In other words, in the planar heating element 100 of this embodiment, the PTC element 5 is provided on the first surface so as to surround the outer periphery of the first surface, so that temperature control can be performed evenly (in other words, without unevenness) across the entire surface of the planar heating element 100 (specifically, the insulating sheet 1). Therefore, the efficiency of temperature control can be improved.

[0073] Furthermore, in the planar heating element 100 of this embodiment, the PTC element 5 and the electrode 11 are connected in series, which allows for more precise temperature control at the electrode 11.

[0074] Furthermore, in the planar heating element 100 of this embodiment, the electrode 11 is provided on the second surface such that a portion of it overlaps with the position of the PTC element 5 on the first surface. Therefore, the temperature of the electrode 11 is quickly transmitted to the PTC element 5, enabling more precise temperature control of the electrode 11.

[0075] Furthermore, in the planar heating element 100 of this embodiment, the heat conductive member 20 is provided on the second surface so as to surround the outer periphery of the second surface and to be in contact with a portion of the electrode 11. Therefore, the temperature of the electrode 11 is transmitted to the PTC element 5 more evenly, and temperature control at the electrode 11 can be achieved with greater precision.

[0076] This disclosure is not limited to the descriptions of embodiments 1 to 3 above, and various modifications are possible without departing from its spirit. [Industrial applicability]

[0077] The planar heating element of this disclosure is useful for a planar heating element in which electrodes and a PTC element are provided on a planar substrate. [Explanation of symbols]

[0078] 1. Insulating sheet 2, 3, 4 electrodes 5 PTC elements Terminals 6, 7, 8, and 9 11, 12 electrodes 12a, 12b Strip-shaped electrodes 12c linear electrode 13 Transparent electrode 14, 15 Strip-shaped electrodes 20 Heat conductive material 100 Planar heating element

Claims

1. An insulating sheet having a first surface and a second surface which is its reverse side, A PTC (Positive Temperature Coefficient) element provided on the first surface, The electrode provided on the second surface, The second surface has a heat conductive member, The PTC element is provided on the first surface so as to surround the outer peripheral portion of the first surface and is connected in series with the electrode. The electrode is provided on the second surface such that a portion of it overlaps with the position of the PTC element on the first surface. The heat conductive member is provided on the second surface so as to surround the outer periphery of the second surface and to be in contact with a portion of the electrode. Planar heating element.

2. The electrode is provided on the second surface such that most of it is located inside the PTC element on the first surface. The planar heating element according to claim 1.

3. The electrode includes at least one of a linear electrode and a strip-shaped electrode. The planar heating element according to claim 1 or 2.

4. The linear electrode or the strip electrode is folded in a zigzag pattern. The planar heating element according to claim 3.

5. The electrode is a transparent electrode provided on the second surface. The planar heating element according to claim 1 or 2.

Images