Planar heating element

Abstract

Conventional heating devices had the problem of not being able to obtain uniform thermal radiation characteristics on the heating device side. [Solution] One aspect of the planar heating element of the present invention includes a first heating element 31 to which a first voltage output from a first control unit is applied, and a second heating element 32 to which a second voltage different from the first voltage is applied, which is output from a second control unit. The first heating element 31 and the second heating element 32 are assembled on a single sheet, and the wiring width is set so that the amount of heat generated per unit area is the same.

Description

Technical Field

[0001] The present invention relates to a planar heating element, for example, a planar heating element in which the heating element is formed in a sheet shape and heats a predetermined surface.

Background Art

[0002] In recent years, many heaters for removing fogging of windshields disposed in front of cameras mounted on automobiles have been proposed. Therefore, an example of a technique related to such a heater is disclosed in Patent Document 1.

[0003] The heating device described in Patent Document 1 includes an image recording device that records image data, a carrier portion whose front side is disposed on the vehicle above or in front of the inside of the vehicle window, a holder that holds the image recording device, and the optical recording axis of the image recording device is coupled to the carrier portion so as to be directed to the front side region of the carrier portion. A heating device formed such that the heat radiation generated by the heating device is radiated in the direction of the front side region of the carrier portion so that the visual recognition region of the image recording device through the vehicle window is not blocked or damaged by heat, and the heating device is formed such that the heat radiation generated by the heating device is radiated in the direction of the front region in front of the front surface of the carrier portion so that the visual recognition region of the image recording device through the vehicle window is not blocked or damaged by fogging or icing, and the radiation power per unit area or unit length is configured to operate differently for two different area portions or length portions, and the radiation power radiates heat to different extents according to the radiation portion and / or the radiation direction. The heating device is disposed on a baffle plate coupled to the carrier portion and is formed in a strip shape, a matrix shape, or a two-dimensional shape on the baffle plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] However, the heating device described in Patent Document 1 had the problem that it could not obtain uniform thermal radiation characteristics on the heating device side. [Means for solving the problem]

[0006] One embodiment of the planar heating element of the present invention includes a first heating element to which a first voltage output from a first control unit is applied, and a second heating element to which a second voltage different from the first voltage is applied, which is output from a second control unit, wherein the first heating element and the second heating element are assembled on a single sheet, and the wiring width and wiring length are set so that the amount of heat generated per unit area is the same. [Effects of the Invention]

[0007] The planar heating element according to the present invention provides a planar heating element that has uniform thermal radiation characteristics on the planar heating element side while controlling two heating elements based on different applied voltages. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram of the heater system according to Embodiment 1. [Figure 2] This is a schematic diagram of a planar heating element according to Embodiment 1. [Figure 3] This diagram illustrates the region in which the same heating power is set in the planar heating element according to Embodiment 1. [Figure 4] This table outlines the specifications of the planar heating element according to Embodiment 1. [Figure 5] This is a cross-sectional view of the bracket according to Embodiment 1. [Figure 6] This is a front view of the bracket according to Embodiment 1. [Figure 7] This is a schematic diagram of a first example of a planar heating element according to Embodiment 2. [Figure 8]This is a schematic diagram of a second example of a planar heating element according to Embodiment 2. [Figure 9] This is a schematic diagram of a third example of a planar heating element according to Embodiment 2. [Modes for carrying out the invention]

[0009] For clarity of explanation, the following descriptions and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are denoted by the same reference numeral, and redundant explanations have been omitted where necessary.

[0010] Embodiment 1 Figure 1 shows a block diagram of the heater system 1 according to Embodiment 1. The heater system according to Embodiment 1 is mounted, for example, on a camera bracket provided adjacent to the windshield of a vehicle, and heats a baffle plate incorporated into the bracket.

[0011] As shown in Figure 1, the heater system 1 according to Embodiment 1 includes a first control unit (e.g., a first ECU 10), a second control unit (e.g., a second ECU 20), and a planar heating element 30. The planar heating element 30 also includes a first heating element 31, a second heating element 32, and a connector 33.

[0012] The first ECU 10 outputs a first applied voltage Vht1 to the first heating element 31 to control the temperature of the first heating element 31. The second ECU 20 outputs a second applied voltage Vht2 to the second heating element 32 to control the temperature of the second heating element 32. The connector 33 is a terminal for connecting the wiring that connects to the first heating element 31 and the second heating element 32.

[0013] Note that, in FIG. 1, the first ECU 10 and the second ECU 20 are shown as processors that control the temperature of the planar heating element 30. However, in FIG. 1, they may also have functions to control a camera (not shown in FIG. 1) and perform processing using an image acquired by the camera. The first ECU 10 and the second ECU 20 are, for example, processors that perform various controls including temperature control of the planar heating element 30 by executing a program in a built-in arithmetic unit.

[0014] In the heater system 1 according to the first embodiment, the first applied voltage Vht1 output by the first ECU 10 and the second applied voltage Vht2 output by the second ECU 20 are different voltages. Specifically, the first applied voltage Vht1 is higher than the second applied voltage Vht2. And, in the heater system 1 according to the first embodiment, a design is made such that the heat dissipation power per unit area of two heating elements to which different applied voltages are applied is the same. And, in the heater system 1 according to the first embodiment, when the area of the first heating region 41 where the first heating element 31 is provided is the same as the area of the second heating region 42 where the second heating element 32 is provided, the first heat dissipation power Hpwr1 which is the heat dissipation power of the first heating region 41 and the second heat dissipation power Hpwr2 which is the heat dissipation power of the second heating region are the same.

[0015] In the heater system 1 according to the first embodiment, since the planar heating element 30 has one of the features, the planar heating element 30 will be described in detail. FIG. 2 shows a schematic view of the planar heating element 30 according to the first embodiment. The outer shape of the planar heating element 30 is determined by the shape of the bracket to be attached and the region to be heated, and the example shown in FIG. 2 is just an example.

[0016] As shown in FIG. 2, the planar heating element 30 has a first heating region 41, a second heating region 42, and a lead portion 43. Also, in FIG. 2, only the connection portion (terminal with the sign of the applied voltage) of the wire wiring to the planar heating element 30 among the connectors 33 is shown. The connection portion between the planar heating element 30 and the wire wiring is covered with, for example, a heat shrink tube.

[0017] The planar heating element 30 is formed by laminating a planar wiring serving as a heating element with two insulating sheets. The insulating sheet is, for example, a polyimide sheet with a thickness of about 0.1 mm. The outer shape of the planar heating element 30 shown in FIG. 2 is the outer shape of this polyimide sheet. And in the heater system 1 of the first embodiment, the planar heating element 30 is formed by disposing planar wirings in the first heating region 41 and the second heating region 42.

[0018] In the example shown in FIG. 2, the areas of the first heating region 41 and the second heating region 42 are set to the same area. Then, a planar wiring serving as the first heating element 31 is disposed in the first heating region 41, and a planar wiring serving as the second heating element 32 is disposed in the second heating region 42. This planar wiring has a strip shape and is composed of a metal wiring with a thickness of about 0.03 mm. This metal wiring may be made of stainless steel (SUS: Steel Use Stainless) or mainly composed of copper.

[0019] And in the heater system 1 according to the first embodiment, the widths and lengths of the planar wirings of the first heating element 31 and the second heating element 32 are adjusted so that the heat dissipation powers of the two heating regions become the same. Specifically, when the wiring width of the planar wiring of the first heating element 31 is W1 and the wiring width of the planar wiring of the second heating element 32 is W2, since the voltage applied to the first heating element 31 is higher, the wiring width is set to satisfy the relationship of W1 < W2. By setting such a wiring width, the resistance value R1 of the first heating element 31 becomes larger than the resistance value R2 of the second heating element 32. And from the relationship between the applied voltage and the wiring resistance, in the example shown in FIG. 2, the heat dissipation powers of the first heating region 41 and the second heating region 42 are designed to be the same.

[0020] Furthermore, in the example shown in Figure 2, the wiring was folded back in order to obtain a wiring length that satisfies the required heat dissipation power for the first heating element 31 and the second heating element 32. In particular, in the example shown in Figure 2, the first heating element 31 and the second heating element 32 were divided equally in a second direction (up and down direction in Figure 2) perpendicular to the first direction (left and right direction in Figure 2) in which the first heating element 31 and the second heating element 32 are aligned, and the line extending in the first direction was defined as the heating region centerline C. Then, in the example shown in Figure 2, a first region and a second region were set up above and below the heating region centerline C, and folded wiring was arranged in each of the first and second regions. In the example shown in Figure 2, a first planar wiring pattern is formed in the first region, and a second planar wiring pattern is formed in the second region, with planar wiring that folds over the heating region centerline C being alternately arranged in the first and second regions. When the folded pattern wiring is divided into multiple regions in this way, the wiring pattern on one side can also be placed on the other divided region, thereby providing a wiring pattern at the boundary between regions and increasing the bending strength of the sheet. Furthermore, by using such a wiring pattern, there are no regions near the heating region centerline C where there is no heating element, thus improving the in-plane uniformity of the heat generation. Note that the wiring pattern that folds over the heating region centerline C only needs to be present on at least one of the first heating element 31 and the second heating element 32.

[0021] Furthermore, as shown in Figure 2, the planar heating element 30 is provided with a lead section 43 on which lead wires 34a and 34b, which serve as power supply paths to the first heating region 41, are arranged by planar wiring similar to that of the first heating region 41 and the second heating region 42. The lead wires 34a and 34b arranged in this lead section 43 may also generate heat, but it is desirable to minimize this heat generation, so the lead wires 34a and 34b are designed to be wider than the wiring width of the first heating element 31. In the configuration shown in Figure 2, the lead section 43 is provided in an area adjacent to the second heating region 42, which is different from the first heating region 41 to which power is supplied.

[0022] Furthermore, in the example shown in Figure 2, the ground terminal G of the first heating element 31 and the ground terminal G of the second heating element 32 are made common terminals. By making the ground terminal G common terminal for the first heating element 31 and the second heating element 32 in this way, it becomes possible to miniaturize the part connecting the planar heating element 30 and the lead wires. In addition, it is possible to reduce the number of parts and assembly parts, thereby reducing manufacturing man-hours.

[0023] Furthermore, lead wirings 34a and 34b can also be replaced with wire wiring. Using wire wiring makes it possible to further reduce the amount of heat generated in the lead section 43.

[0024] In the heater system 1 according to Embodiment 1, the area and heat output of the first heating region 41 and the second heating region 42 are set to be the same. Therefore, Figure 3 shows a diagram illustrating the regions in the planar heating element according to Embodiment 1 that are set to have the same heat output. As shown in Figure 3, in the heater system 1 according to Embodiment 1, the area of ​​the first heating region 41 and the second heating region 42 are set to be the same, and the heat output of the first heating region 41 and the second heating region 42 is set to be the same. Note that, as shown in Figure 3, the lead portion 43 is not included in the heat output region.

[0025] Here, the specifications of the planar heating element 30 will be explained with reference to the table. Figure 4 shows a table illustrating the specifications of the planar heating element 30 according to Embodiment 1. Figure 4 shows the differences in design specifications for the two heating regions, the first heating region 41 and the second heating region 42, in a table format. As shown in Figure 4, in the planar heating element 30, the area of ​​the heating region is the same design value for the first heating region 41 and the second heating region 42. Also, the heat dissipation power per unit area of ​​the heating region is the same design value for the first heating region 41 and the second heating region 42. On the other hand, the voltage applied to the first heating element 31 and the second heating element 32 is such that the first applied voltage Vht1 applied to the first heating element 31 is a higher voltage value than the second applied voltage Vht2 applied to the second heating element 32. This is determined by the specifications of the first ECU 10 and the second ECU 20.

[0026] To satisfy the three specifications described above, in the planar heating element 30, the resistance value R1 of the first heating element 31, which is placed in the first heating region 41, is made greater than the resistance value R2 of the second heating element 32, which is placed in the second heating region 42. Furthermore, to satisfy the characteristics of this resistance value, the wiring width W1 of the first heating element 31, which is placed in the first heating region 41, is made narrower than the wiring width W2 of the second heating element 32, which is placed in the second heating region 42. In addition, due to the differences in applied voltage, resistance value, and wiring width, the applied current Iht1 flowing through the first heating element 31 is less than the applied current Iht2 flowing through the second heating element 32. It is also possible to make the resistance value R1 greater than the resistance value R2 by making the wiring widths W1 and W2 the same and making the wiring length L1 of the first heating element 31 longer than the wiring length L2 of the second heating element 32.

[0027] Next, the method for attaching the planar heating element 30 to the bracket will be explained. Figure 5 shows a cross-sectional view of the bracket according to Embodiment 1. In Figure 6, the left side of the drawing is the interior side of the vehicle, and the right side is the exterior side of the vehicle.

[0028] As shown in Figure 6, a camera 52 is mounted on the bracket 51 to which the planar heating element 30 is attached. The bracket 51 is mounted so as to face the windscreen 50 from the inside of the vehicle, such that the shooting range 53 of the camera 52 faces outwards. The planar heating element 30 is mounted on the inside surface of the bracket 51. The surface of the bracket 51 facing the shooting range 53 is a baffle plate that is treated with an anti-reflective coating or has an anti-reflective structure.

[0029] Next, Figure 6 shows a front view of the bracket according to Embodiment 1. The front view shown in Figure 6 is a view of the windscreen 50 from the outside of the vehicle. In addition, Figure 6 also shows the planar heating element 30 attached to the inside of the bracket 51 to indicate its position, but in reality, the planar heating element 30 cannot be seen from the front.

[0030] As shown in Figure 6, two cameras, a first camera (camera 52a) and a second camera (camera 52b), are mounted on the bracket 51. Since cameras 52a and 52b are mounted in different positions, there is a difference in the shooting ranges of the two cameras. In Figure 6, the shooting range of camera 52a is designated as shooting range 53a, and the shooting range of camera 52b is designated as shooting range 53b. The first heating element 31 of the planar heating element 30 mainly heats the area corresponding to the shooting range 53a of the first camera (e.g., camera 52a), and also heats a portion of the area corresponding to the shooting range 53b of the second camera (e.g., camera 52b). The second heating element 32 of the planar heating element 30 mainly heats the area corresponding to the shooting range 53b of camera 52b, and also heats a portion of the area corresponding to the shooting range 53b of camera 52a.

[0031] As mentioned above, by attaching the planar heating element 30 to the bracket 51, the heat emitted from the planar heating element 30 is transferred to the windscreen 50, thereby removing or preventing fogging of the windscreen 50. In Figure 6, two cameras are used, but the number of cameras may be two or more (for example, three or four).

[0032] As described above, by using the planar heating element 30 according to Embodiment 1, it becomes possible to control multiple heating elements controlled by different applied voltages with the same heat dissipation power. In particular, when the ECUs controlling the first heating element 31 and the second heating element 32 have different voltage output characteristics, it is difficult to control the two heating elements with the same heat dissipation power. However, in the planar heating element 30 according to Embodiment 1, the resistance values ​​of the first heating element 31 and the second heating element 32 are different, and they are designed to have the same heat dissipation power, making it easy to control them with the same heat dissipation power.

[0033] Furthermore, in the planar heating element 30 according to Embodiment 1, the heat dissipation power per unit area of ​​the first heating region 41 and the second heating region 42 are the same, and their areas are also the same. Therefore, in the planar heating element 30, it is possible to make the heat dissipation power of the first heating region 41 and the second heating region 42 the same.

[0034] Furthermore, Patent Document 1 neither discloses nor suggests that the thermal radiation characteristics become uniform across the surface on the planar heating element side for different applied voltages.

[0035] Embodiment 2 Embodiment 2 describes several other forms of the planar heating element 30. In the description of Embodiment 2, the same reference numerals as in Embodiment 1 are used for components that are not described in the same way as in Embodiment 1.

[0036] First, Figure 7 shows a schematic diagram of a planar heating element 30a, which is a first example of a planar heating element according to Embodiment 2. In the example shown in Figure 7, the ground wiring G of the first heating element 31 and the ground wiring G of the second heating element 32 are made into separate terminals.

[0037] Figure 8 shows a schematic diagram of a planar heating element 30b, which is a second example of a planar heating element according to Embodiment 2. In the example shown in Figure 8, in order to minimize the lead portion 43, the connection terminals for the wire wiring for power supply to the first heating element 31 and the connection terminals for ground voltage supply are provided as close as possible to the first heating region 41. In the example shown in Figure 8, the lead wirings 34a and 34b, which form the planar wiring, are extremely short compared to other examples. Even in this configuration, the lead wiring provided in correspondence with the first heating element 31 can be switched to wire wiring.

[0038] Figure 9 shows a schematic diagram of a planar heating element 30c, which is a third example of a planar heating element according to Embodiment 2. In the example shown in Figure 9, a reinforcing portion 44 is provided in a region adjacent to the first heating region 41, with a shape symmetrical to the lead portion 43. The reinforcing portion 44 is provided with floating wiring 35 that is at a floating potential without a potential supply. This floating wiring 35 is made of the same material as the first heating element 31 and the second heating element 32, such as SUS. By providing this reinforcing portion 44, it is possible to increase the rigidity of the planar heating element 30c.

[0039] From the above description, it can be seen that various modifications are possible, such as the connection configuration between the planar heating element 30 and the wire wiring, the configuration of the lead portion 43, and the addition of the reinforcing portion 44. On the other hand, in all of the examples of planar heating elements 30a to 30c according to Embodiment 2, the configuration of the first heating element 31 and the second heating element 32 incorporated into the first heating region 41 and the second heating region 42 is the same. In other words, by maintaining the configuration of the first heating region 41 and the second heating region 42, it becomes possible to control multiple heating elements controlled by different applied voltages with the same heat dissipation power.

[0040] The present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, the above embodiments are: [Explanation of Symbols]

[0041] 1 Heater System 10. First ECU 20 Second ECU 30 Planar heating element 31. First heating element 32. Second heating element 33 Connectors 34a Lead Wiring 34b Lead Wiring 35 Floating Wiring 41 First heating region 42 Second heating region 43 Lead section 44 Reinforcement section 50 Windscreen 51 Bracket 52 Cameras 53 Shooting range Vht1 First applied voltage Vht2 Second applied voltage Hpwr1 First Heat Dissipation Power HPWR2: Second Heat Dissipation Power W1 First line width W2 Second line width C heating area center line

Claims

1. A first heating element to which a first voltage output from a first control unit is applied, It includes a second heating element to which a second voltage different from the first voltage is applied, which is output from a second control unit, The first heating element and the second heating element are incorporated into a single sheet, and the wiring width and wiring length are set so that the amount of heat generated per unit area is the same.

2. The first heating element is provided corresponding to the first heating region, The second heating element is provided corresponding to the second heating region, The planar heating element according to claim 1, wherein the first heating region and the second heating region are set to have the same area.

3. The planar heating element according to claim 2, wherein the first lead wiring that supplies power to the first heating element is arranged along the second heating region in a region different from the first heating region.

4. The planar heating element according to claim 3, wherein the first heating element, the second heating element, and the first lead wiring are formed by planar wiring, and the wiring width of the first lead wiring is wider than the wiring width of the first heating element.

5. The planar heating element according to claim 2, further comprising a floating wiring region provided in a region adjacent to the first heating region, wherein independent floating wiring is provided.

6. The planar heating element according to claim 1, wherein the first heating element and the second heating element are formed by planar wiring.

7. The planar heating element according to claim 1, wherein the first heating element and the second heating element are laminated with an insulating sheet.

8. The first heating element primarily heats the area corresponding to the shooting range of the first camera, and also heats a portion of the area corresponding to the shooting range of the second camera. The planar heating element according to claim 1, wherein the second heating element mainly heats the area corresponding to the shooting range of the second camera and also heats a part of the area corresponding to the shooting range of the first camera.

9. The planar heating element according to claim 8, wherein the first heating element and the second heating element are attached to the back side of the bracket to which the first camera and the second camera are mounted, the back side facing the baffle plate that faces the outside of the vehicle and is the shooting area of ​​the first camera and the second camera.

10. The planar heating element according to claim 1, wherein the first ground terminal for connecting the first heating element to ground and the second ground terminal for connecting the second heating element to ground are provided as a single common terminal.

11. In a second direction perpendicular to the first direction in which the first heating element and the second heating element are aligned, the first heating element and the second heating element are divided equally, and a line extending in the first direction is defined as the center line of the heating region, and at least one of the first heating element and the second heating element is defined as having a first region and a second region straddling the center line of the heating region, a first planar wiring pattern is formed in the first region, a second planar wiring pattern is formed in the second region, and planar wiring that is folded back so as to straddle the center line of the heating region is alternately arranged in the first region and the second region, as described in claim 1.

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