Photovoltaic tile

Abstract

A photovoltaic tile (100). The photovoltaic tile (100) in embodiments of the present application comprises a light-transmitting panel (10), a backboard (20), and a battery cell (30); the panel (10) is a curved panel; the backboard (20) and the panel (10) are stacked, the shape of the backboard (20) is the same as that of the panel (10), and the backboard (20) is a fiber-reinforced thermoplastic composite board (21); and the battery cell (30) is located between the panel (10) and the backboard (20).

Description

Photovoltaic tiles Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a photovoltaic tile. Background Art

[0002] Solar energy is an inexhaustible green energy source. Photovoltaic power generation is currently being applied in a wide range of fields, with building-integrated photovoltaic (BIPV) becoming a growing trend. Residential rooftops are the primary application area for distributed photovoltaics. However, photovoltaic tiles, as a related technology, have low solar energy utilization rates and are prone to power loss during transportation and installation. Summary of the Invention

[0003] The present invention provides a photovoltaic tile.

[0004] The photovoltaic tile of the embodiment of the present application includes a translucent panel, a backboard and a battery cell. The panel is a curved panel, the backboard and the panel are stacked, the shape of the backboard is the same as the shape of the panel, the backboard is a fiber-reinforced thermoplastic composite board, and the battery cell is located between the panel and the backboard.

[0005] In the photovoltaic tiles of the present embodiment, both the front and back panels are curved, increasing the tile's working area, improving solar energy utilization, and enhancing the tile's power generation efficiency. The back panel is a fiber-reinforced thermoplastic composite sheet, which improves its strength and reduces the risk of hidden cracks in the cells during tile manufacturing. It also reduces the back panel's water vapor transmission rate, minimizing the risk of water vapor corrosion on the cells, thereby extending the tile's service life.

[0006] In certain embodiments, the back plate includes at least one curved portion, and the curved portion has a radius of 26 mm to 200 mm.

[0007] This allows for a larger backsheet curvature and a wider range of curvatures, facilitating the creation of diverse shapes for photovoltaic tiles to meet diverse market demands. Furthermore, by reducing the radius of the curved surface, the backsheet's surface area can be increased, increasing the working area of ​​the photovoltaic tile and thereby improving solar energy utilization and power generation efficiency.

[0008] In some embodiments, the number of curved surface portions is 1-10.

[0009] In this way, by increasing the number of curved surfaces, the surface area of ​​the backplane can be increased, and the working area of ​​the photovoltaic tiles can be increased, thereby improving the utilization rate of solar energy and the power generation efficiency of the photovoltaic tiles.

[0010] In some embodiments, when the number of the curved surface portions is at least two, the back plate includes a first curved surface portion and a second curved surface portion connected to the first curved surface portion, and the first curved surface portion and the second curved surface portion have opposite curvature directions.

[0011] In this way, the cross-sectional shape of the back plate is made into a waveform, which improves the three-dimensional sense of the photovoltaic tile and thus enhances the ornamental value of the photovoltaic tile.

[0012] In some embodiments, the first curved surface portions and the second curved surface portions are alternately arranged along an arrangement direction of the first curved surface portions and the second curved surface portions.

[0013] In this way, the photovoltaic tiles can fit closely together, and the upper and lower tile surfaces can be laid not only in a straight line but also in a staggered manner.

[0014] In some embodiments, the first curved portion and the second curved portion have the same curvature radius.

[0015] In this way, the photovoltaic tiles have good symmetry and beautiful shape, and are easy to connect two adjacent photovoltaic tiles and install.

[0016] In some embodiments, the cell is a crystalline silicon cell.

[0017] In this way, crystalline silicon cells can improve the conversion efficiency of solar energy, thereby increasing energy utilization and reducing energy waste.

[0018] In certain embodiments, a fiber-reinforced thermoplastic composite panel includes a matrix and a glass fiber layer disposed in the matrix.

[0019] In this way, the combination of the glass fiber layer and the matrix can enhance the strength of the fiber-reinforced thermoplastic composite board, increase the service life of the backboard, and thus extend the service life of the photovoltaic tile.

[0020] In certain embodiments, the glass fibers of the glass fiber layer have a length of 6 mm to 25 mm.

[0021] In this way, the glass fibers of the glass fiber layer are longer, which can improve the strength of the fiber-reinforced thermoplastic composite board, thereby improving the strength of the backboard and extending the service life of the photovoltaic tile.

[0022] In some embodiments, an adhesive layer is provided between the panel and the battery cell, and between the battery cell and the back plate. The adhesive layer bonds the panel and the battery cell, and bonds the battery cell and the back plate. The thickness of the adhesive layer is 0.2 mm to 0.7 mm.

[0023] In this way, the panel and cells, as well as the cells and backsheet, can be connected and fixed by the adhesive layer, achieving a laminated package of the panel, cells, and backsheet, forming a stable and reliable structure. Furthermore, when the adhesive layer thickness meets the aforementioned requirements, it can act as a buffer between the panel and cells, and between the cells and backsheet, preventing fragmentation caused by lamination.

[0024] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0026] FIG1 is a schematic diagram of the exploded structure of a photovoltaic tile according to an embodiment of the present invention;

[0027] FIG2 is a schematic structural diagram of a fiber-reinforced thermoplastic composite panel according to an embodiment of the present invention.

[0028] Explanation of the reference numerals: 100, photovoltaic tile; 10, panel; 20, backboard; 21, fiber-reinforced thermoplastic composite board; 22, curved surface portion; 23, first curved surface portion; 24, second curved surface portion; 25, substrate; 26, glass fiber layer; 30, cell; 31, crystalline silicon cell; 40, adhesive layer. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0033] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0034] Please refer to Figure 1. The photovoltaic tile 100 of the embodiment of the present application includes a light-transmitting panel 10, a backboard 20 and a battery cell 30. The panel 10 is a curved panel. The backboard 20 is stacked with the panel 10. The shape of the backboard 20 is the same as that of the panel 10. The backboard 20 is a fiber-reinforced thermoplastic composite panel 21. The battery cell 30 is located between the panel 10 and the backboard 20.

[0035] In the photovoltaic tile 100 of the present embodiment, both the panel 10 and the backsheet 20 are curved surfaces, which increases the working area of ​​the photovoltaic tile 100, improves the utilization of solar energy, and enhances the power generation efficiency of the photovoltaic tile 100. The backsheet 20 is a fiber-reinforced thermoplastic composite sheet 21, which improves the strength of the backsheet 20 and reduces the risk of hidden cracks in the cells 30 during the manufacturing process of the photovoltaic tile 100. It also reduces the water vapor transmission rate of the backsheet 20, reducing the risk of water vapor corrosion on the cells 30, thereby extending the service life of the photovoltaic tile 100.

[0036] Specifically, the photovoltaic tile 100 is a roof tile that converts solar energy into electricity. It can be attached to existing roofs or used as a building component, creating a photovoltaic building integration solution. The photovoltaic tile 100 can be flat or curved, and can be installed on either a flat surface or a vertical surface.

[0037] The panel 10 and backsheet 20 form the outermost layer of the photovoltaic tile 100, sealing, insulating, and protecting the cells 30, thereby improving the mechanical properties of the photovoltaic tile 100. The panel 10 and backsheet 20 protect the cells 30 from damage caused by climate fluctuations, such as high temperatures, low temperatures, rain, or hail. They also protect the cells 30 from damage caused by collisions during transportation, effectively improving the photovoltaic tile 100's ability to withstand harsh environments.

[0038] The panel 10 includes a light-receiving surface and a backlight surface. The light-transmitting panel 10 has good light transmittance. The panel 10 serves as the front of the photovoltaic tile 100. Sunlight can pass through the light-receiving surface of the panel 10 to the cell 30, allowing the cell 30 to receive light and convert solar energy into electricity.

[0039] In some embodiments, panel 10 is made of ultra-clear tempered glass. Ultra-clear tempered glass has higher light transmittance and strength, resulting in higher light transmittance and surface strength for photovoltaic tile 100. Ultra-clear tempered glass combines the properties of both ultra-clear glass and tempered glass. Ultra-clear glass is an ultra-transparent, low-iron glass with a light transmittance exceeding 91.5%. Ultra-clear glass also possesses superior physical, mechanical, and optical properties.

[0040] Tempered glass is a prestressed glass that uses physical or chemical methods to create compressive stress on the glass surface. When subjected to external forces, this stress is first offset by the surface stress, thereby increasing the glass's load-bearing capacity and enhancing its impact resistance. Tempered glass of the same thickness has an impact strength 3-5 times that of ordinary glass and a bending strength 3-5 times that of ordinary glass. Tempered glass also has excellent thermal stability and can withstand temperature fluctuations three times that of ordinary glass, including fluctuations of 300°C. The texture and color of ultra-clear tempered glass can be customized to meet specific needs.

[0041] The outer layer of material on the back of the photovoltaic tile 100 is called the backsheet 20. It is a key component of the photovoltaic tile 100. The backsheet 20 isolates the solar cells 30 from the external environment, providing insulation and enabling the cells to operate outdoors for extended periods of time. Different backsheet 20 structures have different functions, and the appropriate backsheet 20 can be selected based on the specific area of ​​use. For example, a fluorine-containing backsheet 20 can be used in areas with strong ultraviolet rays. A white backsheet 20 enhances light reflection and improves power generation efficiency. A black backsheet 20 meets the aesthetic requirements of the roof. A glass backsheet 20 offers high light transmittance.

[0042] The primary function of the cell 30 is power generation. Cells 30 can be categorized as crystalline silicon cells 31 and thin-film cells, each with its own advantages. Crystalline silicon cells 31 have relatively low equipment costs and high photoelectric conversion efficiency, making them suitable for outdoor power generation in sunlight. However, this leads to higher power consumption and cell 30 costs. Thin-film cells have lower power consumption and battery costs, offer better low-light performance, and can generate power even under normal lighting conditions. However, this leads to higher equipment costs and lower photoelectric conversion efficiency.

[0043] Referring to FIG. 1 , in some embodiments, the back plate 20 includes at least one curved portion 22 , and the curved portion 22 has a radius of 26 mm to 200 mm.

[0044] This allows the backsheet 20 to have a larger curvature and a wider range of curvatures, facilitating the PV tile 100 to achieve a variety of shapes and shapes to meet diverse market demands. Furthermore, by reducing the radius of the curved portion 22, the surface area of ​​the backsheet 20 can be increased, thereby increasing the working area of ​​the PV tile 100 and thereby improving the utilization of solar energy and the power generation efficiency of the PV tile 100.

[0045] Specifically, the radius of the curved surface portion 22 can be any one of 26 mm, 30 mm, 60 mm, 90 mm, 120 mm, 150 mm, 180 mm, and 200 mm, or a range of values ​​therebetween. The smaller the radius, the greater the curvature of the curved surface portion 22.

[0046] Referring to FIG. 1 , in some embodiments, the number of the curved surface portions 22 is 1-10.

[0047] In this way, by increasing the number of curved portions 22 , the surface area of ​​the back sheet 20 can be increased, and the working area of ​​the photovoltaic tile 100 can be increased, thereby improving the utilization rate of solar energy and the power generation efficiency of the photovoltaic tile 100 .

[0048] Specifically, the number of the curved surface portions 22 may be any one of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0049] Referring to FIG. 1 , in some embodiments, when the number of the curved surface portions 22 is at least two, the back plate 20 includes a first curved surface portion 23 and a second curved surface portion 24 connected to the first curved surface portion 23 , and the first curved surface portion 23 and the second curved surface portion 24 have opposite bending directions.

[0050] In this way, the cross-section of the back sheet 20 is in a corrugated shape, which enhances the three-dimensional effect of the photovoltaic tile 100 and thus improves the aesthetics of the photovoltaic tile 100 .

[0051] Specifically, the first curved surface portion 23 and the second curved surface portion 24 can be formed as one piece, the first curved surface portion 23 can be bent toward the side close to the panel 10, and the second curved surface portion 24 can be bent toward the side away from the panel 10, or the first curved surface portion 23 can be bent toward the side away from the panel 10, and the second curved surface portion 24 can be bent toward the side close to the panel 10.

[0052] Referring to FIG. 1 , in some embodiments, the first curved surface portions 23 and the second curved surface portions 24 are alternately arranged along their arrangement direction.

[0053] In this way, the photovoltaic tiles 100 can fit closely together, and the upper and lower tile surfaces can be laid not only in a straight line but also in a staggered manner.

[0054] Specifically, the number of the first curved surface portions 23 can be the same as the number of the second curved surface portions 24, or the number of the first curved surface portions 23 can be one more than the number of the second curved surface portions 24. For example, when the number of the first curved surface portions 23 is 1, the number of the second curved surface portions 24 can be 1; when the number of the first curved surface portions 23 is 2, the number of the second curved surface portions 24 can be 2 or 1; when the number of the first curved surface portions 23 is 3, the number of the second curved surface portions 24 can be 3 or 2; when the number of the first curved surface portions 23 is 4, the number of the second curved surface portions 24 can be 4 or 3; when the number of the first curved surface portions 23 is 5, the number of the second curved surface portions 24 can be 5 or 4.

[0055] In some embodiments, the first curved surface portion 23 and the second curved surface portion 24 have the same curvature radius.

[0056] In this way, the photovoltaic tile 100 has good symmetry and beautiful shape, and it is convenient to connect two adjacent photovoltaic tiles 100 and install them easily.

[0057] Specifically, the first curved surface portion 23 and the second curved surface portion 24 may be symmetrical with respect to the center of the connection point, and the curved surface radii of the points of symmetry between the first curved surface portion 23 and the second curved surface portion 24 with respect to the center of the connection point are the same.

[0058] Referring to FIG. 1 , in some embodiments, the cell 30 is a crystalline silicon cell 31 .

[0059] In this way, the crystalline silicon cell 31 can improve the conversion efficiency of solar energy, thereby increasing energy utilization and reducing energy waste.

[0060] Specifically, the crystalline silicon cell 31 can be divided into a monocrystalline silicon cell and a polycrystalline silicon cell. In some embodiments, the crystalline silicon cell 31 can be an XBC cell, which can be formed by organically combining an IBC cell with technologies such as TOPCon, HJT, and perovskite. IBC cells, also known as full back electrode contact cells, are a technology that moves the positive and negative metal contacts of solar cells to the back of the cell. Since there are no grid lines on the front of the cell, the light-receiving area of ​​the cell is greatly increased, thereby improving the power generation efficiency of the photovoltaic tile 100. The number of crystalline silicon cells 31 can be multiple, and multiple crystalline silicon cells 31 can be connected in series or in parallel using shingling technology, splicing technology, or half-cell technology.

[0061] Referring to FIG. 2 , in certain embodiments, a fiber-reinforced thermoplastic composite panel 21 includes a matrix 25 and a glass fiber layer 26 disposed in the matrix 25 .

[0062] In this way, the combination of the glass fiber layer 26 and the matrix 25 can enhance the strength of the fiber-reinforced thermoplastic composite panel 21 , improve the service life of the back panel 20 , and thus extend the service life of the photovoltaic tile 100 .

[0063] Specifically, the glass fiber layer 26 can be formed of fiberglass, which is an inorganic non-metallic material with excellent performance, good insulation, strong heat resistance, good corrosion resistance, and high mechanical strength. The fiber-reinforced thermoplastic composite panel 21 is formed by compounding the matrix 25 material and the reinforcing material through a certain molding process. The matrix 25 can be made of resin materials such as polypropylene (PP), polyethylene glycol terephthalate (PET), polyethylene (PE), polyphenylene sulfide (PPS), and polyether-ether-ketone (PEEK). The reinforcing material can be glass fiber, carbon fiber, or aramid. In some embodiments, the substrate 25 is made of PET, and the glass fiber layer 26 is made of high-strength glass fiber, such as satin-woven glass fiber cloth, in which the glass fiber content is 30%. The mesh structure of the glass fiber cloth formed by the satin weave can better disperse the force during the bending process of the battery cell 30, thereby reducing the hidden cracking phenomenon of the battery cell 30.

[0064] The fiber-reinforced thermoplastic composite panel 21 can be made from PET and glass fiber layers 26 through a melt impregnation process. The glass fiber layers 26 are first preheated and then laminated with PET film extruded from an extruder. Two glass fiber layers 26 are sandwiched between three layers of PET, with the middle layer being molten PET and the top and bottom layers being PET film. This sandwich structure is then fed into a double-belt press, where it is pressurized for impregnation and lamination at a temperature above the melting point of PET but below its degradation temperature, followed by cooling. The fiber-reinforced thermoplastic composite panel 21 can be recycled through methods such as melt reshaping and chip reshaping, contributing to the sustainable use of resources.

[0065] In certain embodiments, the glass fibers of the glass fiber layer 26 have a length of 6 mm to 25 mm.

[0066] In this way, the glass fibers of the glass fiber layer 26 are longer, which can improve the strength of the fiber-reinforced thermoplastic composite panel 21 , thereby improving the strength of the back sheet 20 and extending the service life of the photovoltaic tile 100 .

[0067] Specifically, the length of the glass fibers of the glass fiber layer 26 can be any one of 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, and 25 mm, or a range between any two of them.

[0068] Please refer to Figure 1. In some embodiments, an adhesive layer 40 is provided between the panel 10 and the battery cell 30, and between the battery cell 30 and the back plate 20. The adhesive layer 40 bonds the panel 10 and the battery cell 30, and bonds the battery cell 30 and the back plate 20. The thickness of the adhesive layer 40 is 0.2mm-0.7mm.

[0069] In this way, the panel 10 and the battery cells 30, as well as the battery cells 30 and the backsheet 20, can be connected and fixed by the adhesive layer 40, achieving a laminated package of the panel 10, the battery cells 30, and the backsheet 20, forming a stable and reliable structure. In addition, when the thickness of the adhesive layer 40 meets the above requirements, the adhesive layer 40 can act as a buffer between the panel 10 and the battery cells 30, and between the battery cells 30 and the backsheet 20, preventing fragmentation caused by lamination.

[0070] Specifically, the photovoltaic tile 100 is constructed in the following order according to the structural packaging of the panel 10, the adhesive layer 40, the battery cell 30, the adhesive layer 40, and the back sheet 20. The adhesive layer 40 can be made of one of ethylene-vinyl acetate copolymer, polyolefin elastomer, polyvinyl butyral and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, preferably polyolefin elastomer. The adhesive layer 40 between the panel 10 and the battery cell 30 and the adhesive layer 40 between the battery cell 30 and the back sheet 20 can be made of the same material or different materials. In some embodiments, the panel 10, the back sheet 20, the battery cell 30 and the adhesive layer 40 are all curved structures, such as arched and wavy, and the undulating curvature of the connecting surface is consistent.

[0071] The thickness of the adhesive layer 40 can be any one of 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, and 0.7 mm, or a range of values ​​therebetween. The adhesive layer 40 between the panel 10 and the cell 30 and the adhesive layer 40 between the cell 30 and the backsheet 20 can be the same thickness or different thicknesses.

[0072] Throughout this specification, reference to terms such as "one embodiment," "certain embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative descriptions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0073] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A photovoltaic tile, characterized in that: include: a light-transmitting panel, wherein the panel is a curved panel; a back plate, stacked with the panel, the shape of the back plate being the same as that of the panel, and the back plate being a fiber-reinforced thermoplastic composite plate; and A battery cell is located between the panel and the back panel.

2. The photovoltaic tile according to claim 1, characterized in that: The back plate includes at least one curved surface portion, and the curved surface radius of the curved surface portion is 26 mm-200 mm.

3. The photovoltaic tile according to claim 2, characterized in that: The number of the curved surface portions is 1-10.

4. The photovoltaic tile according to claim 2, characterized in that: When the number of the curved surface portions is at least two, the back plate includes a first curved surface portion and a second curved surface portion connected to the first curved surface portion, and the first curved surface portion and the second curved surface portion have opposite curvature directions.

5. The photovoltaic tile according to claim 4, characterized in that: Along an arrangement direction of the first curved surface portion and the second curved surface portion, the first curved surface portion and the second curved surface portion are alternately arranged.

6. The photovoltaic tile according to claim 4, characterized in that: The first curved surface portion and the second curved surface portion have the same curved surface radius.

7. The photovoltaic tile according to claim 1, characterized in that: The cell is a crystalline silicon cell.

8. The photovoltaic tile according to claim 1, characterized in that: The fiber-reinforced thermoplastic composite panel includes a matrix and a glass fiber layer disposed in the matrix.

9. The photovoltaic tile according to claim 8, characterized in that: The length of the glass fibers in the glass fiber layer is 6 mm to 25 mm.

10. The photovoltaic tile according to claim 1, characterized in that: An adhesive layer is provided between the panel and the battery cell, and between the battery cell and the back plate. The adhesive layer bonds the panel and the battery cell, and bonds the battery cell and the back plate. The thickness of the adhesive layer is 0.2 mm to 0.7 mm.

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