JP2021026861A - Heater substrate with conductive film - Google Patents

Abstract

To provide a heater substrate with a conductive film that can effectively increase the heat generation efficiency in a light-transmitting area.SOLUTION: A heater substrate 1 with a conductive film includes a transparent substrate 2, a first bus bar electrode 3 and a second bus bar electrode 4, which are arranged on the transparent substrate 2 and face each other, and a conductive film 5 disposed on the transparent substrate 2 and in contact with the first busbar electrode 3 and the second busbar electrode 4. Inner portions 3b, 4b of at least one of the electrodes of the first bus bar electrode 3 and the second bus bar electrode 4 in plan view are arc-shaped portions 7a, 8a constituting a part of circles 7, 8, and a central angle θ of the arc-shaped portions 7a, 8a is 20 degrees or more and 135 degrees or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heater substrate with a conductive film in which a conductive film is arranged on a transparent substrate.

Conventionally, a heater substrate with a conductive film has been used for in-vehicle applications such as in-vehicle cameras and in-vehicle displays, and for security cameras. Such a heater substrate with a conductive film is used as a heater for defrosting a cover glass and preventing dew condensation in, for example, an in-vehicle camera. Further, in a liquid crystal display device such as an in-vehicle display, it is used to maintain the response speed of the liquid crystal when used in a low temperature environment.

As an example of such a heater substrate with a conductive film, Patent Document 1 below discloses a rectangular heater in which a conductive thin film material is uniformly formed on the substrate. In Patent Document 1, bus bar electrodes having opposite sides parallel to each other are provided on two opposite sides of a rectangular heater so as to cause a predetermined voltage drop. Then, connection terminals for power supply are provided on both ends of these bus bar electrodes.

Further, Patent Document 2 below discloses an energized heating glass in which a transparent conductive film and a pair of bus bar electrodes for energizing the transparent conductive film are provided on a glass plate. In Patent Document 2, a transparent conductive film is provided on the surface of a glass plate, and a pair of bus bar electrodes are provided on the transparent conductive film. Further, the energizing portion of the bus bar electrode to the transparent conductive film is formed so as to face each other with the transparent conductive film sandwiched between them.

Japanese Unexamined Patent Publication No. 7-99081 Japanese Unexamined Patent Publication No. 2001-122643

In recent years, the number of cameras installed in automobiles has been increasing more and more. Further, in automobiles, the installation of a large number of sensors such as a sensor called LiDAR (rider) that detects an object by laser light is also being considered. Therefore, the cover glass used for such cameras and sensors is also required to have higher performance.

By the way, in the heater substrate with a conductive film as in Patent Document 1 and Patent Document 2, a bus bar electrode and a transparent conductive film are provided on a rectangular plate-shaped glass substrate, thereby forming a display area of a liquid crystal display device or the like. The light transmitting region is heated. However, the heater substrate with a conductive film as in Patent Document 1 and Patent Document 2 has sufficient heat generation efficiency in the light transmitting region, particularly when a disk-shaped glass substrate such as a cover glass of a camera or a sensor is used. There is a problem that it cannot be increased. Therefore, when the heater substrate with a conductive film of Patent Document 1 or Patent Document 2 is used, it cannot be said that the cover glass of the camera or the sensor can be sufficiently defrosted and dew condensation is prevented, and the reliability can be sufficiently improved. There is a problem that it cannot be done.

An object of the present invention is to provide a heater substrate with a conductive film, which can effectively increase heat generation efficiency in a light transmitting region.

The heater substrate with a conductive film according to the present invention is arranged on the transparent substrate and the transparent substrate, and is arranged on the transparent substrate with the first bus bar electrode and the second bus bar electrode facing each other. The first bus bar electrode and the conductive film in contact with the second bus bar electrode are provided, and the plane of at least one of the first bus bar electrode and the second bus bar electrode is provided. The inner portion in view is an arc-shaped portion forming a part of a circle, and the central angle of the arc-shaped portion is 20 degrees or more and 135 degrees or less.

In the present invention, the shape of the transparent substrate is preferably a disk shape.

In the present invention, it is preferable that the first bus bar electrode and the second bus bar electrode have an arcuate shape.

In the present invention, the heater substrate with a conductive film is provided with a rectangular light transmitting region in a plan view, and the light transmitting region is formed from the first bus bar electrode and the second bus bar electrode in a plan view. The following equation (1), where L is the length of the light transmitting region, W is the width of the light transmitting region, and R is the radius of the circle forming the arcuate portion. ) Satisfy.

0.5 ≤ (L ² + W ² ) ^{1/2 /} 2R ≤ 0.95 ... Equation (1)

In the present invention, it is preferable that at least a part of the first bus bar electrode and the second bus bar electrode is covered with the conductive film.

In the present invention, it is preferable that an antireflection film is further laminated on the main surface of the conductive film arranged on the transparent substrate.

In the present invention, it is preferable that an antireflection film is laminated on the main surface of the transparent substrate opposite to the conductive film.

In the present invention, the conductive film is preferably a transparent conductive film.

In the present invention, it is preferable that the conductive film is made of indium tin oxide.

According to the present invention, it is possible to provide a heater substrate with a conductive film, which can effectively increase heat generation efficiency in a light transmitting region.

It is a schematic plan view which shows the heater substrate with a conductive film which concerns on 1st Embodiment of this invention. It is a schematic cross-sectional view of the part along the line AA of FIG. It is a schematic plan view for demonstrating the light transmission region in the heater substrate with a conductive film which concerns on 1st Embodiment of this invention. The heat generation density when the central angle of the arcuate portion which is the inner portion in the plan view of the first bus bar electrode and the second bus bar electrode of the heater substrate with a conductive film according to the first embodiment of the present invention is 60 degrees. It is a figure which shows the distribution. The heat generation density when the central angle of the arcuate portion which is the inner portion in the plan view of the first bus bar electrode and the second bus bar electrode of the heater substrate with a conductive film according to the first embodiment of the present invention is 30 degrees. It is a figure which shows the distribution. The heat generation density when the central angle of the arcuate portion which is the inner portion in the plan view of the first bus bar electrode and the second bus bar electrode of the heater substrate with a conductive film according to the first embodiment of the present invention is 120 degrees. It is a figure which shows the distribution. It is a schematic plan view which shows the heater substrate with a conductive film which concerns on 2nd Embodiment of this invention. It is a schematic cross-sectional view which shows the heater substrate with a conductive film which concerns on 3rd Embodiment of this invention. It is a schematic cross-sectional view which shows the heater substrate with a conductive film which concerns on 4th Embodiment of this invention. It is a figure which shows the relationship between the central angle of the arc-shaped part which is the inner part in the plan view in the 1st bus bar electrode and the 2nd bus bar electrode of the heater substrate with a 1st conductive film, and the heat generation efficiency. It is a figure which shows the relationship between the central angle of the arc-shaped part which is the inner part in the plan view in the 1st bus bar electrode and the 2nd bus bar electrode of the heater substrate with a 2nd conductive film, and the heat generation efficiency. It is a figure which shows the relationship between the central angle of the arc-shaped part which is the inner part in the plan view in the 1st bus bar electrode and the 2nd bus bar electrode of the heater substrate with a 3rd conductive film, and the heat generation efficiency. In the first to third conductive heater substrates, the length of the diagonal line of the light transmission region with respect to the diameter of the circle forming the arc-shaped portion which is the inner portion in the plan view of the first bus bar electrode and the second bus bar electrode. It is a figure which shows the relationship between the ratio of, and the peak efficiency of heat generation.

Hereinafter, preferred embodiments will be described. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Further, in the drawings, members having substantially the same function may be referred to by the same reference numerals.

(First Embodiment)
FIG. 1 is a schematic plan view showing a heater substrate with a conductive film according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a portion along the line AA of FIG.

As shown in FIGS. 1 and 2, the heater substrate 1 with a conductive film includes a transparent substrate 2, a first bus bar electrode 3, a second bus bar electrode 4, and a conductive film 5.

The shape of the transparent substrate 2 is not particularly limited, but in the present embodiment, it has a disk shape. The transparent substrate 2 does not have to have a perfect disc shape, and may have a substantially disc shape. When the shape of the transparent substrate 2 is a disk shape, the diameter of the transparent substrate 2 can be, for example, 10 mm or more and 300 mm or less. Further, the thickness of the transparent substrate 2 can be, for example, 30 μm or more and 5 mm or less.

The transparent substrate 2 is preferably a substrate that is transparent in the wavelength range used by cameras, sensors, display devices, and the like. The material of the transparent substrate 2 is not particularly limited, and examples thereof include glass and resin. Further, if the wavelength range used is an infrared region, it may be Si, Ge, or the like. Examples of the glass include soda-lime glass, borosilicate glass, non-alkali glass, crystallized glass, quartz glass and the like. Further, it may be aluminosilicate glass used as tempered glass.

The transparent substrate 2 has a first main surface 2a and a second main surface 2b that face each other. A conductive film 5 is provided on the first main surface 2a of the transparent substrate 2. In the present embodiment, the shape of the conductive film 5 is also a disk shape. However, the shape of the conductive film may be substantially a disk shape and is not particularly limited. The conductive film 5 may be in contact with the first bus bar electrode 3 and the second bus bar electrode 4. When the shape of the conductive film 5 is a disk shape, the diameter of the conductive film 5 can be, for example, 8 mm or more and 300 mm or less. The diameter of the conductive film 5 may be the same as the diameter of the transparent substrate 2. The thickness of the conductive film 5 can be, for example, 10 nm or more and 50 μm or less.

The conductive film 5 is preferably a transparent conductive film. Examples of the conductive film 5 include indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), indium zinc oxide (IZO), fluorine tin oxide (FTO), and antimony tin. A transparent conductive film made of a composite oxide thin film having conductivity such as an oxide (ATO) can be used. Among them, the conductive film 5 is preferably indium tin oxide (ITO) from the viewpoint of low resistance, high transmittance, and high weather resistance.

The conductive film 5 can be obtained by forming the conductive film 5 on the transparent substrate 2. The film forming method of the conductive film 5 is not particularly limited, and for example, a vapor deposition method, a sputtering method, a CVD method, or the like can be used.

A first bus bar electrode 3 and a second bus bar electrode 4 are provided on the conductive film 5. The first bus bar electrode 3 and the second bus bar electrode 4 have an arcuate shape. In particular, when the transparent substrate 2 has a disk-like shape, the first bus bar electrode 3 and the second bus bar electrode 4 have an arcuate shape, so that the cylindrical housing of the camera, sensor, etc. It is easy to mount and positioning can be performed even more easily.

Specifically, in a plan view, the inner portion 3b located inside of the outer peripheral edge 3a of the first bus bar electrode 3 is an arc-shaped portion 7a forming a part of the circle 7. The outer portion 3c located on the outer side of the outer peripheral edge 3a of the first bus bar electrode 3 is an arc-shaped portion 8a forming a part of the circle 8. The line segment connecting the arcuate portion 7a and the arcuate portion 8a is the width of the first bus bar electrode 3. In this way, the first bus bar electrode 3 having an arcuate shape is configured.

Further, in a plan view, the inner portion 4b located inside of the outer peripheral edge 4a of the second bus bar electrode 4 is an arc-shaped portion 7b forming a part of the circle 7. The outer portion 4c located on the outer side of the outer peripheral edge 4a of the second bus bar electrode 4 is an arc-shaped portion 8b forming a part of the circle 8. The portion connecting the arcuate portion 7b and the arcuate portion 8b is the width of the second bus bar electrode 4. In this way, the second bus bar electrode 4 having an arcuate shape is configured.

In this embodiment, the circles 7 and 8 are concentric circles. Further, the first bus bar electrode 3 and the second bus bar electrode 4 are provided so as to be line-symmetric with respect to the straight line passing through the center O. Therefore, in the present embodiment, the central angle, which is the opening angle of the arcuate portion 7a and the arcuate portion 7b, is the same θ. In the present embodiment, the central angle θ, which is the opening angle, is 20 degrees or more and 135 degrees or less.

In the present invention, the shapes of the first bus bar electrode 3 and the second bus bar electrode 4 do not have to be arcuate, and may be substantially arcuate. Alternatively, it may have another shape. The inner portion 3b located inside of the outer peripheral edge 3a of the first bus bar electrode 3 may form an arc-shaped portion 7a forming a part of the circle 7. Alternatively, the inner portion 4b located inside of the outer peripheral edge 4a of the second bus bar electrode 4 may form an arc-shaped portion 7b that forms a part of the circle 7. Therefore, the inner portion of at least one of the first bus bar electrode 3 and the second bus bar electrode 4 in the plan view may be an arcuate portion forming a part of a circle. Further, the arcuate portion does not have to be a perfect arc, and may be a substantially arc.

Further, the first bus bar electrode 3 and the second bus bar electrode 4 are preferably provided line-symmetrically with respect to a straight line passing through the center O, but may be substantially line-symmetrical, and the positional relationship thereof may be defined. There is no particular limitation.

Lead wires can be attached to the first bus bar electrode 3 and the second bus bar electrode 4. By applying a voltage between the first bus bar electrode 3 and the second bus bar electrode 4 through the lead wire, the heater substrate 1 with a conductive film can be heated.

As described above, the first bus bar electrode 3 and the second bus bar electrode 4 are electrodes through which electricity flows, and the material constituting them is not particularly limited, but for example, Ag, Al, Cu, Pt, Au. , Ir, Ti, Ni, Cr, Mo, W, Sn and the like, or alloys of these metals can be used. Of these, Ag or Au having high conductivity is preferable.

The widths of the first bus bar electrode 3 and the second bus bar electrode 4 can be, for example, 1 mm or more and 10 mm or less, respectively. The thickness of the first bus bar electrode 3 and the second bus bar electrode 4 can be, for example, 50 nm or more and 50 μm or less, respectively.

The method for forming the first bus bar electrode 3 and the second bus bar electrode 4 is not particularly limited, but can be formed by, for example, a screen printing method, an inkjet printing method, a vapor deposition method, a sputtering method, a CVD method, or the like.

FIG. 3 is a schematic plan view for explaining a light transmission region in the heater substrate with a conductive film according to the first embodiment of the present invention.

As shown in FIG. 3, in the heater substrate 1 with a conductive film, a light transmitting region 6 is provided on the conductive film 5. The light transmission region 6 is provided inside the first bus bar electrode 3 and the second bus bar electrode 4 in a plan view. Further, in the present embodiment, the light transmission region 6 has a rectangular shape in a plan view. The width W of the light transmitting region 6 is not particularly limited, but is 12 mm in the present embodiment. The length L of the light transmitting region 6 is not particularly limited, but is 9 mm in the present embodiment.

The light transmission region 6 is, for example, an region corresponding to an imaging area when the heater substrate 1 with a conductive film is used for a camera such as an in-vehicle camera. When used in a sensor such as a sensor called LiDAR (rider) that detects an object by a laser image, it is a sensing area. Further, when used in a liquid crystal display device such as an in-vehicle display, it is an area corresponding to the display area of the liquid crystal display device. The size and shape of the light transmitting region 6 can be appropriately determined depending on the application in which the heater substrate 1 with a conductive film is used.

The feature of this embodiment is that the inner portion of at least one of the first bus bar electrode 3 and the second bus bar electrode 4 in a plan view is an arc-shaped portion forming a part of a circle, and the arc-shaped portion thereof. The central angle θ, which is the opening angle of the portion, is 20 degrees or more and 135 degrees or less. Thereby, the heat generation efficiency in the light transmitting region 6 can be effectively increased. This point can be explained as follows with reference to FIGS. 4 to 6.

FIG. 4 shows that the central angle of the arcuate portion which is the inner portion in the plan view of the first bus bar electrode and the second bus bar electrode of the heater substrate with a conductive film according to the first embodiment of the present invention is 60 degrees. It is a figure which shows the heat generation density distribution at the time. Further, FIG. 5 is a diagram showing a heat generation density distribution when the central angle of the arcuate portion is 30 degrees, and FIG. 6 is a diagram showing a heat generation density distribution when the central angle of the arcuate portion is 120 degrees. It is a figure. In FIGS. 4 to 6, the radius R of the arcuate portions 7a and 7b is 8 mm, the width W of the light transmitting region 6 is 12 mm, and the length L of the light transmitting region 6 is 9 mm. ..

As shown in FIGS. 4 to 6, in any case, heat generation is concentrated at the tips of the first bus bar electrode 3 and the second bus bar electrode 4 (hereinafter, may be simply referred to as bus bar electrodes). You can see that. Further, from FIG. 4, it can be seen that when the central angle θ is 60 degrees, heat is generated most uniformly and efficiently in the light transmission region 6. This is because when the central angle θ is 60 degrees, the tips of the first bus bar electrode 3 and the second bus bar electrode 4 (the portions where heat generation is concentrated) are arranged near the four corners of the light transmission region 6. As a result, it is considered that the inside of the light transmitting region 6 can be heated uniformly and efficiently.

On the other hand, as shown in FIG. 5, as the central angle θ becomes smaller, the tips of the bus bar electrodes get closer to each other, and as a result, heat generation is concentrated in that portion. Therefore, it is considered that the light transmission region 6 is not sufficiently heated. On the other hand, as shown in FIG. 6, as the central angle θ becomes larger, the tips of the first bus bar electrode 3 and the second bus bar electrode 4 become closer to each other, and as a result, heat generation is concentrated in that portion. ing. Therefore, even in this case, it is considered that it is difficult for the light transmitting region 6 to be sufficiently heated.

As described above, the present inventors have found that when a bus bar electrode having arcuate portions 7a and 7b is used, heat generation is concentrated at the tip of the bus bar electrode. Focusing on the heat generated at the tip of the bus bar electrode, the heat generation efficiency of the light transmitting region 6 is effectively increased when the central angles θ of the arcuate portions 7a and 7b are in the range of 20 degrees or more and 135 degrees or less. I found that it was possible. This point can also be confirmed from the examples described later.

In the present invention, the central angles θ of the arcuate portions 7a and 7b are preferably 30 degrees or more, more preferably 40 degrees or more, still more preferably 50 degrees or more, preferably 120 degrees or less, and more preferably 110 degrees, respectively. Below, it is more preferably 100 degrees or less. When the central angles θ of the arcuate portions 7a and 7b are within the above range, the heat generation efficiency in the light transmission region 6 can be further effectively increased.

^{Further, in the present invention, the ratio of the diagonal length (L 2} + W ² ) ^1/2 of the light transmission region 6 to the diameter 2R of the circle 7 constituting the arcuate portions 7a and 7b is the ratio of the following equation (1). It is preferable to satisfy the relationship. The closer the arcuate portions 7a and 7b are to the light transmitting region 6, the more the heat generation efficiency of the light transmitting region 6 tends to be increased. Can be further enhanced.

0.5 ≤ (L ² + W ² ) ^{1/2 /} 2R ≤ 0.95 ... Equation (1)

The lower limit of the ratio (L ² + W ² ) ^1/2 / 2R is preferably 0.55, more preferably 0.6, and ^{the upper limit of the ratio (L 2} + W ² ) ^1/2 / 2R is preferable. Is 0.94, more preferably 0.93. In this case, the heat generation efficiency in the light transmitting region 6 can be further effectively increased.

The heater substrate 1 with a conductive film of the present embodiment can effectively increase the heat generation efficiency in the light transmission region 6 as described above. Therefore, when it is used as a cover glass for a camera, a sensor, or the like mounted on an automobile, the dew condensation prevention effect can be enhanced. Further, when used in a liquid crystal display device such as an in-vehicle display, the response speed at the time of use in a low temperature environment can be maintained.

Therefore, the heater substrate 1 with a conductive film can be suitably used for a camera or sensor mounted on an automobile, or a liquid crystal display device such as an in-vehicle display. In particular, it can be suitably used for a sensor called LiDAR (rider) that detects an object by a laser image.

(Second Embodiment)
FIG. 7 is a schematic plan view showing a heater substrate with a conductive film according to a second embodiment of the present invention. As shown in FIG. 7, in the heater substrate 21 with a conductive film, the first bus bar electrode 3 and the second bus bar electrode 4 are directly provided on the first main surface 2a of the transparent substrate 2. An adhesion layer may be provided between the first bus bar electrode 3 and the second bus bar electrode 4 and the transparent substrate 2. The extraction electrodes 22 and 23 are connected to the first bus bar electrode 3 and the second bus bar electrode 4, respectively. A conductive film 5 is provided so as to cover the first bus bar electrode 3, the second bus bar electrode 4, and the extraction electrodes 22 and 23. In the lower part of the conductive film 5, the extraction electrodes 22 and 23 are drawn out to the end of the heater substrate 21 with a conductive film. The heater substrate 21 with a conductive film can be heated by applying a voltage between the first bus bar electrode 3 and the second bus bar electrode 4 through the extraction electrodes 22 and 23 drawn out to the ends. In FIG. 7, the first bus bar electrode 3, the second bus bar electrode 4, and the extraction electrodes 22 and 23 provided below the conductive film 5 are shown by broken lines. Other points are the same as those in the first embodiment.

Also in the second embodiment, the inner portion of at least one of the first bus bar electrode 3 and the second bus bar electrode 4 in the plan view is an arcuate portion forming a part of the circle, and the circle thereof. The central angle θ of the arc-shaped portion is 20 degrees or more and 135 degrees or less. Thereby, the heat generation efficiency in the light transmitting region 6 can be increased. Therefore, when it is used as a cover glass for a camera, a sensor, or the like mounted on an automobile, the effect of defrosting and preventing dew condensation can be enhanced. Further, when used in a liquid crystal display device such as an in-vehicle display, the response speed at the time of use in a low temperature environment can be maintained.

(Third and Fourth Embodiments)
FIG. 8 is a schematic cross-sectional view showing a heater substrate with a conductive film according to a third embodiment of the present invention. As shown in FIG. 8, in the heater substrate 31 with a conductive film, the antireflection film 32 is provided on the conductive film 5 arranged on the first main surface 2a of the transparent substrate 2. Other points are the same as those of the second embodiment.

Further, FIG. 9 is a schematic cross-sectional view showing a heater substrate with a conductive film according to a fourth embodiment of the present invention. As shown in FIG. 9, in the heater substrate 41 with a conductive film, the antireflection film 42 is also provided on the second main surface 2b of the transparent substrate 2. Other points are the same as those in the third embodiment.

The antireflection films 32 and 42 are not particularly limited, respectively, but for example, SiO ₂ , Al ₂ O ₃ , TIO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , SiN, SiON, AlN, AlON, MgF. _A single-layer or multi-layer dielectric film composed of 2, BaF ₂ , Si, SiH, Ge, ZnS, ZnSe and the like can be used.

Also in the third embodiment and the fourth embodiment, the inner portion of at least one of the first bus bar electrode 3 and the second bus bar electrode 4 in a plan view has an arc shape forming a part of a circle. It is a portion, and the central angle θ of the arcuate portion is 20 degrees or more and 135 degrees or less. Thereby, the heat generation efficiency in the light transmitting region 6 can be increased. Therefore, when it is used as a cover glass for a camera, a sensor, or the like mounted on an automobile, the effect of defrosting and preventing dew condensation can be enhanced. Further, when used in a liquid crystal display device such as an in-vehicle display, the response speed of the liquid crystal when used in a low temperature environment can be maintained.

Further, in the third embodiment and the fourth embodiment, since the antireflection films 32 and 42 are further provided, the light transmittance can be further increased.

An antifouling film for preventing fingerprints from adhering and imparting water repellency and oil repellency may be provided on the second main surface 2b of the transparent substrate 2. When the antireflection film 42 is provided on the second main surface 2b of the transparent substrate 2, the antifouling film can be formed on the antireflection film 42.

The antifouling film preferably contains a fluorine-containing silane compound in the antifouling layer forming composition, and can be prepared by coating with a silane compound solution having a fluoroalkyl group or a fluoroalkyl ether group. In particular, it is preferable that the fluorine-containing silane compound is silazane or alkoxysilane. Further, among the silane compounds having a fluoroalkyl group or a fluoroalkyl ether group, the fluoroalkyl group in the silane compound is bonded to the Si atom at a ratio of 1 or less with respect to 1 Si atom, and the rest. Is preferably a silane compound which is a hydrolyzable group or a siloxane binding group. The hydrolyzable group referred to here is, for example, a group such as an alkoxy group, which becomes a hydroxyl group by hydrolysis, whereby the silane compound can form a polycondensate.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples, and can be appropriately modified and implemented without changing the gist thereof.

(Examples and comparative examples)
Hereinafter, in Examples and Comparative Examples, the first to third heater substrates with a conductive film were produced by setting each parameter of the heater substrate 1 with a conductive film described in the first embodiment as follows. The diameter of each transparent substrate 2 was set to 30 mm.

First heater substrate with conductive film;
Width W = 12 mm of light transmitting region 6, length L = 9 mm of light transmitting region 6, radius R: 8 mm, 11 mm, 13 mm, central angle θ: 10 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 Every time

Second heater substrate with conductive film;
Width W = 9 mm of light transmitting region 6, length L = 9 mm of light transmitting region 6, radius R: 8 mm, 11 mm, 13 mm, central angle θ: 10 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 Every time

Third heater substrate with conductive film;
Width W = 6 mm of light transmission region 6, length L = 9 mm of light transmission region 6, radius R: 8 mm, 11 mm, 13 mm, central angle θ: 10 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 Every time

Next, a voltage was applied to the first to third heater substrates with a conductive film to heat each heater substrate with a conductive film. Then, the heat generation efficiency (%) in each sample was obtained from the heat generation amount of the light transmitting region 6 with respect to the heat generation amount of the entire conductive film 5. The results are shown in FIGS. 10 to 12. Note that FIG. 10 shows the result of the first conductive film heater substrate, FIG. 11 shows the result of the second conductive film heater substrate, and FIG. 12 shows the result of the third conductive film heater substrate. The result of the board is shown.

The calorific value of the light transmission region 6 was calculated from the calorific value distribution obtained by the following numerical simulation.

In the numerical simulation used in the examples of the present invention, an energized region composed of a bus bar electrode (silver electrode) serving as a positive electrode and a negative electrode and a transparent conductive film (ITO film) is modeled, and the energized region is divided into a plurality of cells. The potential distribution when the positive electrode and the negative electrode were divided and a potential for a predetermined electric power was applied to the positive electrode and the negative electrode was obtained by the finite volume method. Since almost no electricity flows through the glass when the ITO film is energized through the electrodes, the glass is not modeled in this embodiment.

In the finite volume method used in the embodiment of the present invention, the electric potential in the cell is an unknown number, and the electric potential is solved by iterative method to solve the simultaneous equations composed of the discretized governing equations by each element. The distribution was obtained. Further, in the embodiment of the present invention, the simulation is carried out on the premise of the DC energized state, and it is assumed that the Laplace equation holds as the governing equation. Assuming that the potential is φ and the conductivity is γ, − ▽ · (γ ▽ φ) = 0. In the embodiment of the present invention, γ is assumed to be a constant, and the above equation is ▽ ² φ = 0.

The calorific value distribution was calculated from the obtained potential distribution. The heat generation density Q of each cell is calculated by the following formula.

In equation (2), A is the area of the surface surrounding the cell, and A in bold letters is the outward normal vector of the surface. ▽ φ and φ are the electric field and potential in the above plane, and are calculated by interpolation using the potential of each cell already obtained.

From FIGS. 10 to 12, it can be seen that in each of the first to third heater substrates with a conductive film, the heat generation efficiency is enhanced when the central angle θ is 30 degrees or more and 120 degrees or less. On the other hand, when the central angle θ was 10 degrees and when the central angle was 150 degrees, the heat generation efficiency could not be sufficiently increased.

From this, regardless of the radius R of the arcuate portions 7a and 7b and the size of the light transmitting region 6, the heat generation efficiency of the light transmitting region 6 is improved by setting the central angle θ to 20 degrees or more and 135 degrees or less. I was able to confirm that I would get it.

It can be seen that in the first to third heater substrates with a conductive film, the larger the width W of the light transmitting region 6 and the smaller the radius R of the arcuate portions 7a and 7b, the higher the heat generation efficiency. ..

From this, it was confirmed that in the heater substrate with the first to third conductive films, the heat generation efficiency is improved as the distance between the first bus bar electrode 3 and the second bus bar electrode 4 and the light transmission region 6 is shorter. did it.

Further, FIG. 13 shows light transmission with respect to the diameter of a circle forming an arcuate portion which is an inner portion in a plan view of the first bus bar electrode and the second bus bar electrode in the first to third heater substrates with a conductive film. It is a figure which shows the relationship between the ratio of the diagonal length of a region, and the peak efficiency of heat generation.

From FIG. 13, the ratio ^{of the diagonal length (L 2} + W ² ) ^1/2 of the diameter 2R of the circles 7 constituting the arcuate portions 7a and 7b to the diameter 2R of the light transmitting region 6 regardless of the size of the light transmitting region 6. It was confirmed that the peak efficiency of heat generation was enhanced when ((L ² + W ² ) ^{1/2 / 2R) was 0.5 or more and 0.95 or less.}

1,21,31,41 ... Heater substrate with conductive film 2 ... Transparent substrate 2a ... First main surface 2b ... Second main surface 3 ... First bus bar electrodes 3a, 4a ... Outer peripheral edges 3b, 4b ... Inner portion 3c, 4c ... Outer portion 4 ... Second bus bar electrode 5 ... Conductive film 6 ... Light transmitting region 7, 8 ... Circle 7a, 7b, 8a, 8b ... Arc-shaped portion 22, 23 ... Drawer electrode 32, 42 ... Antireflection film

Claims (9)

With a transparent board
The first busbar electrode and the second busbar electrode, which are arranged on the transparent substrate and face each other,
A conductive film which is arranged on the transparent substrate and is in contact with the first bus bar electrode and the second bus bar electrode.
With
The inner portion of at least one of the first bus bar electrode and the second bus bar electrode in a plan view is an arcuate portion forming a part of a circle.
A heater substrate with a conductive film having a central angle of 20 degrees or more and 135 degrees or less in the arcuate portion. The heater substrate with a conductive film according to claim 1, wherein the transparent substrate has a disk shape. The heater substrate with a conductive film according to claim 1 or 2, wherein the first bus bar electrode and the second bus bar electrode have an arcuate shape. The heater substrate with a conductive film is provided with a rectangular light transmitting region in a plan view.
The light transmitting region is provided inside the first bus bar electrode and the second bus bar electrode in a plan view.
A claim that satisfies the relationship of the following formula (1) when the length of the light transmitting region is L, the width of the light transmitting region is W, and the radius of the circle forming the arcuate portion is R. The heater substrate with a conductive film according to any one of 1 to 3.
0.5 ≤ (L ² + W ² ) ^{1/2 /} 2R ≤ 0.95 ... Equation (1) The heater substrate with a conductive film according to any one of claims 1 to 4, wherein at least a part of the first bus bar electrode and the second bus bar electrode is covered with the conductive film. The heater substrate with a conductive film according to any one of claims 1 to 5, wherein an antireflection film is further laminated on the main surface of the conductive film arranged on the transparent substrate. The heater substrate with a conductive film according to any one of claims 1 to 6, wherein an antireflection film is laminated on a main surface of the transparent substrate opposite to the conductive film. The heater substrate with a conductive film according to any one of claims 1 to 7, wherein the conductive film is a transparent conductive film. The heater substrate with a conductive film according to any one of claims 1 to 8, wherein the conductive film is made of indium tin oxide.