Planar heating element

Abstract

To provide a planar heating element capable of improving the efficiency of temperature control.SOLUTION: A planar heating element includes an insulating sheet having a first surface and a second surface that is the back surface thereof, a positive temperature coefficient (PTC) element provided on the first surface, and an electrode provided on the second surface, and the PTC element is provided on the first surface so as to surround the outer circumferential portion of the first surface, and is connected in series with the electrode, and the electrode is provided on the second surface such that a part of the electrode overlaps with the position of the PTC element in the first surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a sheet heating element. [Background technology]

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

[0003] [Patent Document 1] Patent Publication No. 2021-125383 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional sheet heating elements have room for improvement in terms of temperature control efficiency.

[0005] An object of one aspect of the present disclosure is to provide a planar heating element that can improve the efficiency of temperature control. [Means for solving the problem]

[0006] A planar heating element according to one embodiment of the present disclosure comprises an insulating sheet having a first surface and a second surface which is the reverse of the first surface, a PTC (Positive Temperature Coefficient) element provided on the first surface, and an electrode provided on the second surface, wherein the PTC element 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, and the electrode is provided on the second surface so that a portion of the electrode overlaps with the position of the PTC element on the first surface. [Effects of the Invention]

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

[0008] [Figure 1] FIG. 1 is a front view showing a first surface of a sheet heating element according to a first embodiment of the present disclosure. [Figure 2] FIG. 1 is a front view showing a second surface of a sheet heating element according to a first embodiment of the present disclosure. [Figure 3] FIG. 1 is a front view showing a second surface superimposed on a first surface of a sheet heating element according to a first embodiment of the present disclosure. [Figure 4] FIG. 10 is a front view showing a second surface of the sheet heating element according to the second embodiment of the present disclosure. [Figure 5] FIG. 10 is a front view showing a second surface superimposed on a first surface of a sheet heating element according to a second embodiment of the present disclosure. [Figure 6] FIG. 11 is a front view showing a second surface of the sheet heating element according to the third embodiment of the present disclosure. [Figure 7] FIG. 10 is a front view showing the second surface superimposed on the first surface of the sheet heating element according to the third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a sheet heating element 100 according to first to third embodiments of the present disclosure will be described with reference to Figures 1 to 7. Note that common components in the figures are given the same reference numerals, and their description will be omitted where appropriate.

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

[0011] 1 to 3, the sheet heating element 100 has an insulating sheet 1 as an electrically insulating base material. The insulating sheet 1 is a planar member having a first surface and a second surface which is the rear surface of the first surface.

[0012] As shown in FIGS. 1 to 3, the sheet 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, electrodes 2 to 4 and a PTC element (which may also be called a PTC resistor) 5 are provided on a first surface of the sheet heating element 100 (specifically, the first surface of the insulating sheet 1).

[0014] On the other hand, as shown in FIG. 2, an electrode 11 is provided on the second surface of the sheet heating element 100 (specifically, the second surface of the insulating sheet 1).

[0015] The PTC element 5 is an element with a self-temperature control function (a function that limits the current by increasing the resistance value when a predetermined temperature is reached). As shown in Figures 1 and 3, the PTC element 5 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).

[0016] 1 and 3, the electrodes 2 to 4 are spaced apart from one another, thereby ensuring electrical insulation between the electrodes 2 to 4.

[0017] 1 and 3, the electrodes 2 to 4 are provided with a terminal 6, terminals 7 to 8, and a terminal 9, respectively. These terminals 6 to 9 are conductive members for electrically connecting the first surface side and the second surface side of the insulating sheet 1.

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

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

[0020] Terminal 9 is provided so as to penetrate electrode 4 and insulating sheet 1. Terminal 9 is electrically connected to electrode 11 on the second surface side, as shown in FIGS.

[0021] Although not shown, each of the electrodes 2 and 4 has 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 periphery 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 multiple comb teeth arranged in parallel and spaced apart from each other, and these are arranged to surround the outer periphery of insulating sheet 1. The tips of the multiple comb teeth are arranged near electrode 4 without contacting it. Similarly, the comb-tooth-shaped portion of electrode 4 includes multiple comb teeth arranged in parallel and spaced apart from each other, and these are arranged to surround the outer periphery of insulating sheet 1. The tips of the multiple comb teeth are arranged near electrode 2 without contacting it. The multiple comb teeth of electrode 2 and the multiple comb teeth of electrode 4 are interlocked so as not to contact each other. The PTC element 5 is provided on each of the comb-tooth-shaped portions of electrodes 2 and 4 that are interlocked in this manner.

[0023] Electrode 11 is a linear electrode. As shown in Figures 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. Most of electrode 11 is zigzag.

[0024] 3, electrode 11 is provided on the second surface so that a portion of it overlaps the position of PTC element 5 provided on the first surface. Also, as shown in FIG. 3, electrode 11 is provided on the second surface so that a majority of it is located inside PTC element 5 provided on the first surface (the area surrounded by PTC element 5).

[0025] The electrode 11 may be, for example, a pre-patterned metal wire arranged on the insulating sheet 1, or may be a metal layer arranged on the insulating sheet 11 that has been patterned by etching, cutting, or the like.

[0026] Next, a description will be given of the flow of current in the sheet heating element 100 configured as described above. Note that the description will be given here taking as an example a case where the current input end is terminal 7 and the current output end is terminal 6.

[0027] A current that flows into terminal 7 from a lead wire (not shown) connected to the first surface side of terminal 7 reaches terminal 8 via electrode 3 on the first surface.

[0028] Next, the current that has passed through terminal 8 flows through electrode 11 on the second surface and reaches terminal 9. This current flow causes electrode 11 to generate heat.

[0029] Next, the current that has passed through terminal 9 flows through electrode 4, PTC element 5, and electrode 2 on the first surface in this order, before reaching terminal 6. This current causes PTC element 5 to function as a heating element that performs self-temperature control. The current then flows into a lead wire (not shown) connected to the first surface side of terminal 6.

[0030] From this flow of current, it can be said that the PTC element 5 is connected in series with the electrode 11.

[0031] The input and output terminals of the current may be the terminals 6 and 7, respectively. In this case, the current flows in the reverse order to that described above.

[0032] (Embodiment 2) The sheet heating element 100 according to embodiment 2 will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a front view showing the second surface of the sheet heating element 100 according to embodiment 2. Fig. 5 is a front view showing the second surface shown in Fig. 4 superimposed on the first surface shown in Fig. 1.

[0033] The first surface of the sheet heating element 100 according to the second embodiment is the same as that of the first embodiment (see FIG. 1), and therefore a description thereof will be omitted here.

[0034] As shown in FIG. 4, the second surface of the sheet heating element 100 is provided with electrodes 12 including strip electrodes 12a, 12b and a linear electrode 12c.

[0035] One end of the strip electrode 12a is connected to the terminal 8. A part of the strip electrode 12a is provided along the right side of the second surface.

[0036] One end of the strip electrode 12b is connected to the terminal 9. A part of the strip electrode 12b is provided along the left side of the second surface.

[0037] The linear electrode 12c includes three zigzag-shaped portions (hereinafter referred to as zigzag portions). One end of each zigzag portion is connected to the strip electrode 12a, and the other end is connected to the strip electrode 12b.

[0038] The electrodes 12 are formed by, for example, printing (e.g., screen printing) a conductive paste (e.g., copper paste or silver paste) onto the insulating sheet 1 to form a pattern, but are not limited to this and may be formed by other methods.

[0039] 5, electrode 12 is provided on the second surface so that a portion thereof (for example, a portion of linear electrode 12c) overlaps with the position of PTC element 5 provided on the first surface. Also, as shown in FIG. 5, electrode 12 is provided on the second surface so that a majority thereof (for example, a majority of linear electrode 12c) is located inside PTC element 5 provided on the first surface (area surrounded by PTC element 5).

[0040] Next, a description will be given of the flow of current in the sheet heating element 100 configured as described above. Note that the description will be given here taking as an example a case where the current input end is terminal 7 and the current output end is terminal 6.

[0041] A current that flows into terminal 7 from a lead wire (not shown) connected to the first surface side of terminal 7 reaches terminal 8 via electrode 3 on the first surface.

[0042] Next, the current that has passed through terminal 8 flows through electrodes 12a, 12c, and 12b in this order on the second surface, and reaches terminal 9. This current flow causes electrode 12 to generate heat.

[0043] Next, the current that has passed through terminal 9 flows through electrode 4, PTC element 5, and electrode 2 on the first surface in this order, before reaching terminal 6. This current causes PTC element 5 to function as a heating element that performs self-temperature control. The current then flows into a lead wire (not shown) connected to the first surface side of terminal 6.

[0044] From this flow of current, it can be said that the PTC element 5 is connected in series with the electrode 12.

[0045] The input and output terminals of the current may be the terminals 6 and 7, respectively. In this case, the current flows in the reverse order to that described above.

[0046] (Embodiment 3) The sheet heating element 100 according to embodiment 3 will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a front view showing the second surface of the sheet heating element 100 according to embodiment 3. Fig. 7 is a front view showing the second surface shown in Fig. 6 superimposed on the first surface shown in Fig. 1.

[0047] The first surface of the sheet heating element 100 according to embodiment 3 is the same as that of embodiment 1 (see FIG. 1), and therefore a description thereof will be omitted here. In this embodiment, since a transparent electrode 13 is used, it is preferable that the insulating sheet 1 also be made of a transparent material.

[0048] As shown in FIG. 6, a transparent electrode 13 and strip-shaped electrodes 14 and 15 are provided on the second surface of the sheet heating element 100.

[0049] The transparent electrode 13 is provided on almost the entire second surface (excluding the lower portion of the second surface) of the insulating sheet 1. Examples of the transparent electrode 13 include, but are not limited to, an AG (silver) film or an ITO (indium tin oxide) film.

[0050] One end of the strip electrode 14 is connected to the terminal 8. A part of the strip electrode 14 is provided along the right side of the second surface and in contact with the transparent electrode 13.

[0051] One end of the strip electrode 15 is connected to the terminal 9. A part of the strip electrode 15 is provided along the left side of the second surface and in contact with the transparent electrode 13.

[0052] Moreover, since the transparent electrode 13 is provided on almost the entire second surface, a portion of the transparent electrode 13 overlaps the position of the PTC element 5 provided on the first surface, as shown in Fig. 7. Moreover, as shown in Fig. 7, the transparent electrode 13 is provided on the second surface so that the majority of it is located inside the PTC element 5 provided on the first surface (the area surrounded by the PTC element 5).

[0053] Next, a description will be given of the flow of current in the sheet heating element 100 configured as described above. Note that the description will be given here taking as an example a case where the current input end is terminal 7 and the current output end is terminal 6.

[0054] A current that flows into terminal 7 from a lead wire (not shown) connected to the first surface side of terminal 7 reaches terminal 8 via electrode 3 on the first surface.

[0055] Next, the current that has passed through terminal 8 flows through electrode 14, transparent electrode 13, and electrode 15 on the second surface in this order, and reaches terminal 9. This current flow causes transparent electrode 13 to generate heat.

[0056] Next, the current that has passed through terminal 9 flows through electrode 4, PTC element 5, and electrode 2 on the first surface in this order, before reaching terminal 6. This current causes PTC element 5 to function as a heating element that performs self-temperature control. The current then flows into a lead wire (not shown) connected to the first surface side of terminal 6.

[0057] From this flow of current, it can be said that the PTC element 5 is connected in series with the transparent electrode 13 and the electrodes 14 and 15 .

[0058] The input and output terminals of the current may be the terminals 6 and 7, respectively. In this case, the current flows in the reverse order to that described above.

[0059] The sheet heating element 100 according to the third embodiment is attached to a transparent member of an optical device (such as a protective glass provided in front of an imaging element) by, for example, double-sided tape. Examples of optical devices include, but are not limited to, an in-vehicle camera (which may also be called a collision prevention camera) that detects the situation around the vehicle, a surveillance camera attached to a building, or an in-vehicle electronic door mirror. The sheet heating element 100 may also be attached to a transparent member (such as a glass window of a vehicle) provided other than the optical device.

[0060] The above has described the sheet heating elements 100 according to embodiments 1 to 3. The effects of the sheet heating elements 100 according to embodiments 1 to 3 will be summarized below.

[0061] The sheet heating element 100 of this embodiment has an insulating sheet 1 having a first surface and a second surface which is the reverse side of the first surface, a PTC element 5 provided on the first surface, and an electrode 11 (electrode 12 in embodiment 2, transparent electrode 13 in embodiment 3; the same applies below) provided on the second surface, and is characterized in that 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, and the electrode 11 is provided on the second surface so that a portion of it overlaps the position of the PTC element 5 on the first surface.

[0062] That is, in the sheet 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, evenly) over the entire surface of the sheet heating element 100 (specifically, the insulating sheet 1), thereby improving the efficiency of temperature control.

[0063] Furthermore, in the planar heating element 100 of this embodiment, the PTC element 5 and the electrode 11 are connected in series, so that the temperature control at the electrode 11 can be realized with higher precision.

[0064] Furthermore, in the planar heating element 100 of this embodiment, the electrode 11 is provided on the second surface so that a portion of it overlaps the position of the PTC element 5 on the first surface, so that the temperature of the electrode 11 is quickly transferred to the PTC element 5, thereby enabling more accurate temperature control of the electrode 11.

[0065] The present disclosure is not limited to the explanations of the above first to third embodiments, and various modifications are possible without departing from the spirit of the present disclosure. [Industrial Applicability]

[0066] The sheet heating element of the present disclosure is useful as a sheet heating element having electrodes and a PTC element provided on a planar substrate. [Explanation of symbols]

[0067] 1 Insulation sheet 2, 3, 4 electrodes 5 PTC element Terminals 6, 7, 8, and 9 11, 12 electrodes 12a, 12b Strip electrodes 12c linear electrode 13 Transparent electrode 14, 15 Strip electrodes 100 Planar heating element

Claims

1. an insulating sheet having a first surface and a second surface that is the reverse surface of the first surface; a PTC (Positive Temperature Coefficient) element provided on the first surface; an electrode provided on the second surface, the PTC element is provided on the first surface so as to surround an outer periphery of the first surface, and is connected in series with the electrode; the electrode is provided on the second surface so that a portion of the electrode overlaps with the position of the PTC element on the first surface; Surface heating element.

2. The electrodes include at least one of linear electrodes and strip electrodes. The sheet heating element according to claim 1 .

3. The linear electrode or the strip electrode is zigzag. The sheet heating element according to claim 2 .

4. The electrode is a transparent electrode provided on the second surface. The sheet heating element according to claim 1 .

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