Clock glass

Abstract

The invention relates to a watch glass (1), in particular for a wristwatch, comprising a cover plate (4) made of diamond. The watch glass (1) can comprise a layer in the form of a carrier plate (6) with a lower refractive index than the cover plate (4) and a thickness (503) greater than the wavelengths of visible light, and / or at least one layer in the form of a coating with a lower refractive index than the cover plate (4) and a thickness (501) greater than the wavelengths of visible light. The invention further relates to a method for producing such a watch glass (1). Furthermore, the invention relates to a watch (40) comprising such a watch glass (1).

Description

[0001] The invention relates to a watch glass, in particular for a wristwatch.

[0002] Watch glasses made of mineral glass or sapphire glass are known from the state of the art.

[0003] The object of the invention is to propose a watch glass with good mechanical and optical properties.

[0004] This problem is solved by a watch glass, in particular for a wristwatch, having the features according to the independent claims.

[0005] According to a first advantageous embodiment, the watch glass, in particular for a wristwatch, can comprise a cover plate made of diamond. Furthermore, the watch glass comprises a layer designed as a carrier plate with a lower refractive index than the cover plate, and / or at least one layer designed as a coating with a lower refractive index than the cover plate. The at least one layer designed as a coating is arranged in particular on / at the inside of the cover plate. The cover plate represents the outside of the watch glass, and the layer designed as a carrier plate is oriented towards the interior of a watch case. The design of the cover plate made of diamond has the advantage that it is 100% scratch-resistant and has a high-quality flair. A further important advantage of the proposed watch glass is explained below. Diamond is one of the natural materials with the highest refractive indices.In particular, diamond has a refractive index of approximately 2.41. This means that light passing through a single disc of diamond loses at least 17% through reflection upon entering the disc (depending on the angle). Upon exiting the disc, it loses at least 17% again. Once the light in a watch with a single disc of diamond has reached the hands, numerals, and dial and returns to the disc, it loses another 17% and another 17% upon exiting the disc on its way back to the viewer's eye. The end result is a noticeable gray haze or darkening that impairs the view of the hands and dial, as less than 50% of the incoming light returns to the viewer.The layer formed as a carrier disc and / or the at least one layer formed as a coating ensures that at the interface between the diamond cover disc and the layer formed as a carrier disc and / or the at least one layer formed as a coating, the difference in refractive index between the two optical media is no longer as high as it would be if there were a single disc made of diamond as a watch glass and air. The light balance therefore looks much better. The grey haze is therefore significantly reduced and - depending on the colour of the watch face - is no longer as strong or is no longer a problem at all. Preferably, all layers and discs of the watch glass are permeable to visible light.

[0006] The proposed watch glass is also shatter-resistant, particularly if it comprises the layer formed as a carrier plate and the cover plate, in the case of a monocrystalline, synthetic diamond cover plate, is manufactured in the crystallographic orientation described below as preferred, or, in the case of a polycrystalline, synthetic diamond cover plate, is oriented as described below as preferred. The watch glass also has good optical properties, particularly if it has the coating formed as at least one layer and / or is laminated to the carrier plate, which has a lower refractive index than diamond.

[0007] The watch glass according to the first advantageous embodiment can preferably further comprise a double layer on / on the outer side of the cover plate. The double layer comprises a diamond layer and an additional layer between the cover plate and the diamond layer. The additional layer has a lower refractive index than the cover plate and the diamond layer, i.e., a lower refractive index than the cover plate and a lower refractive index than the diamond layer. The diamond layer is advantageously thinner than the cover plate.

[0008] The layer formed as a carrier disk and / or the at least one layer formed as a coating preferably each has a thickness significantly greater than the wavelengths of visible light, preferably greater than 2 µm. This has the effect that no interference effects occur in the layer formed as a carrier disk and / or in the at least one layer formed as a coating.

[0009] The layer formed as a carrier disc and / or the at least one layer formed as a coating can preferably extend over at least 80%, more preferably over at least 90%, more preferably over 100% of the surface, i.e. over the entire surface, of the watch glass, in particular over the entire surface of the cover disc on the inside of the cover disc. In particular, if the carrier disc extends over 100% of the entire surface of the watch glass, it is arranged over its entire surface on the inside of the cover disc. Accordingly, if the coating extends over 100% of the entire surface of the watch glass, it is arranged in particular over its entire surface on the inside of the cover disc. If a coating, in particular produced by means of PVD (physical vapor deposition), is provided on the inside of the cover disc, it can alternatively be designed such that it is not arranged over its entire surface on the inside of the cover disc.In this alternative embodiment, the coating does not extend to the edge of the watch glass, in particular the cover plate, or ends before the edge of the watch glass, in particular the cover plate.

[0010] According to a second advantageous embodiment, the watch glass, in particular for a wristwatch, can comprise a cover plate made of diamond and a double layer on the outside of the cover plate. The double layer has a diamond layer and at least one additional layer between the cover plate and the diamond layer. The at least one additional layer preferably has a lower refractive index than the cover plate and the diamond layer, i.e., a lower refractive index than the cover plate and a lower refractive index than the diamond layer. The diamond layer is advantageously thinner than the cover plate.

[0011] The additional layer is preferably formed from a dielectric material. Advantageously, the refractive index and thickness of the at least one additional layer and the thickness of the diamond layer are selected such that the reflections at the boundary transitions between the additional layer and the diamond layer at least partially, in particular completely, compensate each other outwardly.

[0012] Further advantageous embodiments of the watch glass and its components, which are described below, relate both to the watch glass according to the first advantageous embodiment and to the watch glass according to the second advantageous embodiment, unless explicit reference is made to the first or the second embodiment or it follows from the wording that only the first or only the second embodiment is possible.

[0013] The inner side of the cover plate is, in particular, that side of the cover plate which, when the watch glass is mounted in a watch, faces an interior of the watch, in particular a watch case (watch case), and / or at least one hand of the watch and / or at least one dial. "Facing" means that the inner side is closer to the interior and / or to the at least one hand and / or to the dial than an outer side of the cover plate. The outer side of the cover plate faces away from the interior and / or the at least one hand and / or the dial.

[0014] The cover plate can preferably be made exclusively of diamond.

[0015] If the watch glass comprises both a layer formed as a carrier plate and a layer formed as a coating, it is understood that the watch glass comprises at least two layers in addition to the cover plate. The coating is a first layer and the carrier plate is a second layer, with an intermediate layer, in particular a laminating film or adhesive layer, being located between the first layer (the coating) and the second layer (the carrier plate).

[0016] The cover plate preferably has a thickness of at least 0.1 mm, preferably at least 0.3 mm, more preferably at least 0.5 mm, preferably at least 0.75 mm, and more preferably at least 1 mm. The thickness of the cover plate is preferably at most 3 mm.

[0017] This can result in optical advantages for the watch glass. This is explained below. When passing through an optical medium with a higher optical density than air and parallel interfaces, an obliquely incident light ray is slightly offset because it is refracted towards the normal to the interface when it enters the optically denser medium and then refracted away from the normal to the interface when it exits. The exiting light ray is parallel to the incoming light ray, but is slightly offset behind the cover plate. This offset is proportional to the thickness of the optically denser medium, or to the length of the path the light ray travels in the optically denser medium at a different directional angle. Since the change in direction of the light ray in diamond is the greatest that ever occurs, a greater thickness of the cover plate means a greater offset of the light ray.While the offset upon the return of the light is compensated for by the reverse offset upon its journey through the diamond crystal, this does change the captured, visible area within the interior of the watch, particularly the area between the hands and dial. Since it can be assumed that the wearer of a watch with the above-described crystal will not always look exactly perpendicularly through the crystal, a thinner cover plate with a less offset view of the interior of the watch, particularly the area between the hands and dial, is more visually appealing than a thicker cover plate.

[0018] Preferably, the cover plate is made of synthetic diamond. However, it is also conceivable for the cover plate to be made of natural diamond. However, manufacturing the cover plate from synthetic diamond is preferred over manufacturing the cover plate from natural diamond.

[0019] The above-mentioned upper limits for the thickness of the cover plate are particularly advantageous when the cover plate is made of synthetic diamond. This reduces the likelihood of optical defects that can occur during the production of synthetic diamond, particularly during the crystallization process, for example, due to the ingress of foreign molecules or due to contamination by particles in the gas mixture. This also reduces the manufacturing costs of the cover plate.

[0020] The cover plate is preferably made of polycrystalline synthetic diamond or monocrystalline synthetic diamond. The cover plate made of polycrystalline synthetic diamond has the advantage of having no cleavage planes and significantly higher elasticity. The fracture strength of a cover plate made of polycrystalline synthetic diamond with a small thickness is therefore significantly better than that of monocrystalline diamond glass. On the other hand, a cover plate made of monocrystalline synthetic diamond has higher clarity than one made of polycrystalline synthetic diamond. Furthermore, the growth rate of the monocrystalline substrates / seeds for producing a cover plate made of monocrystalline synthetic diamond is higher.

[0021] According to an advantageous variant of the first advantageous embodiment of the watch glass, the watch glass comprises the layer designed as a carrier disc, which is firmly connected to the cover disc. In particular, the carrier disc can have a thickness of at least 0.3 mm, preferably at least 0.5 mm, more preferably at least 1 mm, more preferably at least 1.5 mm. The above-mentioned upper limits for the cover disc can also be taken into account in this embodiment of the invention. In particular, the carrier disc can be thicker than the cover disc. Furthermore, the carrier disc can in particular be made of a different material than the cover disc. In other words, the carrier disc cannot be made of diamond. In particular, the carrier disc can in particular be made exclusively of glass, in particular of a glass with an expansion coefficient between 0.001 x 10 -6 K -1 and 2 x 10 -6 K -1, can be manufactured. In particular, the carrier disc can be made of quartz glass, Sitall, Vycor, Zerodur, Cer Vit, plastic, or sapphire glass. Due to the similar expansion coefficients of the carrier disc and cover disc, a stable bond between the cover disc and the carrier disc can be achieved even when temperatures change. Quartz glass is particularly well-suited for the carrier disc because, in addition to having a similar expansion coefficient to diamond, quartz glass has very interesting chemical and physical properties. The expansion coefficient is defined at room temperature, specifically at 25 degrees Celsius.

[0022] Advantageously, the watch glass comprises a layer designed as an intermediate layer (connecting intermediate layer) between the cover plate and the carrier plate. The intermediate layer firmly connects the cover plate to the carrier plate. The intermediate layer can in particular consist of one or more sub-layers. The multiple sub-layers can be made of the same material or different materials. The production of the watch glass with the intermediate layer between the cover plate and the carrier plate, i.e. in other words the production of the watch glass as laminated composite glass, enables a particularly shatter-resistant watch glass because in the event of an impact on the watch glass, the impact energy can be absorbed by the cover plate via the intermediate layer from the carrier plate. In addition, laminating the cover plate to the carrier plate is a cost-effective process because it allows the thickness of the cost-intensive cover plate to be significantly reduced.In addition to the two advantages of shatter resistance and cost-effectiveness, laminating the cover plate to the carrier plate has another advantage. The high refractive index of the cover plate means that at the four transitions of the incoming and outgoing light at the boundary between diamond and another optical medium, a portion of the light is lost through reflection. Because the difference in refractive index between these two optical media (diamond intermediate layer) at the interface between the diamond of the cover plate and the intermediate layer is smaller than the difference in refractive index between diamond and air, the light balance of the laminated watch glass is improved. In particular, a gray haze that can occur with a non-laminated watch glass can be reduced and - depending on the color of the watch dial - is no longer as pronounced or is no longer disturbing at all.In one embodiment of the invention, with a laminated watch glass, the aforementioned at least one coating on the inside of the cover plate can be omitted. This simplifies the manufacture of the watch glass. A further advantage of the laminated watch glass is that when light passes through the watch glass, the beam offset is lower than when passing through a non-laminated watch glass due to the lower refractive index of the intermediate layer and the carrier plate compared to diamond (cover plate) with the same overall thickness.

[0023] In particular, the intermediate layer between the cover plate and the carrier plate can be thinner than the cover plate and / or the carrier plate.

[0024] However, it is also possible for the intermediate layer to be thicker than the cover plate. For example, the intermediate layer can have a thickness of 0.78 mm, with the cover plate having a thickness of 0.5 mm or 0.3 mm. For this purpose, a laminating film, in particular an EVA film, with a thickness of 0.1 mm to 0.8 mm can be used. According to another example, the intermediate layer can have a thickness of 0.58 mm. To produce the intermediate layer, for example, a first laminating film, in particular a first EVA film, with a thickness of 0.38 mm, and a second laminating film, in particular a second EVA film, with a thickness of 0.2 mm can be used. The cover plate can be 0.5 mm thick and thus thinner than the intermediate layer.

[0025] In particular, the intermediate layer between the cover pane and the carrier pane can each consist of at least one cured adhesive layer, preferably of a cured UV adhesive, or of at least one laminating layer made of / with EVA, PVB, Sentry Glass or another laminating film.

[0026] In particular, the intermediate layer between the cover plate and the carrier plate can have a refractive index equal to the refractive index of the carrier plate, up to + / - Δn = 0.4, preferably up to + / - Δn = 0.2. "Δn" represents the difference between the refractive index of the intermediate layer and the refractive index of the carrier plate. Preferably, the refractive index of the intermediate layer can be equal to the refractive index of the carrier plate.

[0027] In particular, the intermediate layer between the cover plate and the carrier plate can have a refractive index between 1.4 and 1.6, in particular 1.48.

[0028] In particular, the intermediate layer between the cover plate and the carrier plate can have a thickness of at least 0.05 mm, preferably at least 0.1 mm. Furthermore, the intermediate layer between the cover plate and the carrier plate, individually or in total, can have a thickness of at most 0.8 mm, preferably at most 0.4 mm.

[0029] According to an advantageous variant of the first advantageous embodiment of the watch glass, the watch glass can be designed as a single-pane watch glass, with only the cover plate and the at least one layer formed as a coating on the cover plate, in particular on the inner side of the cover plate. The single-pane watch glass can also comprise the double layer. In particular, the term "single-pane watch glass" means that the watch glass does not comprise the carrier plate.

[0030] According to an advantageous variant of the first advantageous embodiment, the watch glass comprises the at least one layer in the form of a coating. The coating is advantageously applied to the inside of the cover plate. In the case of a watch glass designed as a single-pane watch glass, the inside of the cover plate is advantageously the exposed inside, whereas in the case of a double-pane watch glass, namely a watch glass with the cover plate and the carrier plate, the inside is the laminated side. The laminated side is the side of the cover plate which, in contrast to the outside of the cover plate, faces the interior of the watch, in particular the case, the watch and / or the at least one hand and / or the dial of the watch, when the watch is assembled.

[0031] According to an advantageous variant of the first advantageous embodiment, the watch glass comprises at least one layer formed as a coating. Advantageously, the coating, formed as a multiple coating, can comprise several coating layers arranged one above the other, made of the same or different materials. Preferably, the coating layers have a gradually lower refractive index from the outside to the inside. The continuously graded refractive indices of the coating layers can significantly reduce the reflection loss that would otherwise occur in a watch glass without a coating at the transition between the cover plate and air.A refractive index which is lower from the outside to the inside means in particular that, in the assembled state of the watch glass, a coating plane which, in comparison to another coating plane, faces the interior of the watch, in particular the case of the watch, and / or the at least one hand of the watch and / or the dial of the watch, has a lower refractive index than the other coating plane.

[0032] According to an advantageous variant of the first advantageous embodiment of the watch glass, at least two of the layers, preferably all of the layers (the layers here can be at least two of the following layers: layer formed as a carrier disc, the at least one layer formed as a coating, and the layer formed as an intermediate layer), have a gradually lower refractive index from the outside to the inside. However, this gradation of the refractive index may not apply to a transition from an intermediate layer (laminate layer or adhesive layer) to a carrier disc. The latter may have a higher refractive index than the intermediate layer due to the material.A lower refractive index from the outside to the inside means in particular that in the assembled state of the watch glass, a layer which, compared to another layer, faces the interior of the watch, in particular the watch case, and / or the at least one hand of the watch and / or the watch dial, has a lower refractive index than the other layer. This applies in particular to all layers. It should be noted here, however, that all of the layers here are layers that are significantly thicker than a wavelength of visible light, preferably greater than 2µm. Thus, the continuously graded refractive indices of the layers can significantly reduce the reflection loss that would otherwise occur with a watch glass without a coating at the transition between the cover plate and air.

[0033] According to an advantageous variant of the first advantageous embodiment of the watch glass, the refractive index on the inside of the cover plate can be reduced to at least 1.8, preferably at least 1.5, by at least one, preferably at least two, more preferably at least three, of the layers.

[0034] According to an advantageous variant of the first advantageous embodiment of the watch glass, the watch glass can comprise at least one layer formed as an anti-reflective coating. In particular, the anti-reflective coating can be applied to one or more planes in which the refractive index is reduced to at least 1.8, preferably at least 1.5. In particular, each layer is formed as an anti-reflective coating or each anti-reflective coating is matched to the media adjacent to it. The anti-reflective coating(s) is / are advantageously applied to an inner side of the cover plate and / or to an inner side of an intermediate layer between the cover plate and the carrier plate and / or to an inner side of the carrier plate. The anti-reflective coating(s) can reduce reflection loss when the light emerges from the respective medium to which the anti-reflective coating(s) is / are applied, thus increasing the light yield.It should be noted that with anti-reflective coatings, the different expansion coefficients of the various materials do not play such a major role, since these coatings are very thin (e.g. 0.5 µm) and therefore elastic, and since watch glasses are not expected to be subject to very large temperature fluctuations.

[0035] By providing one or more layers designed as anti-reflective coatings, the optical effect of the watch glass can be improved. However, it is also possible, particularly in the case of a laminated watch glass in which the cover plate is bonded to the carrier plate by means of the intermediate layer, to dispense with the anti-reflective coating(s), since the optical effect of the watch glass can be improved by the optical properties of the intermediate layer.

[0036] In particular, the previously mentioned gradual reduction of the refractive index can be achieved by: • Laminating the cover disc with the carrier disc without additional coating. • Multiple coating of a non-laminated single-pane watch glass (cover plate without carrier plate) on its inside, with a graduated refractive index. • single-layer coating on the laminated side of the cover plate in the case of a multi-layer watch glass (safety glass). • Multiple coating on the laminated side of the cover plate in the case of a multi-layer watch glass (safety glass). • Multiple coating on the laminated side of the cover plate in the case of a multi-layer watch glass (safety glass) and additional single coating on the inside of the carrier plate (the side of the carrier plate facing an interior of the watch, in particular a watch case, and / or at least one hand of the watch and / or at least one dial) • Single coating on the laminated side of the cover plate in the case of a multi-layer watch glass (safety glass) and additional single coating on the inside of the carrier plate (the side of the carrier plate facing an interior of the watch, in particular a watch case, and / or at least one hand of the watch and / or at least one dial) • Combination of a single or multiple coating of one of the above-mentioned watch glass surfaces to gradually reduce the difference in refractive index with a single or multi-layer anti-reflective coating.

[0037] By applying multiple coatings to the inside of the cover plate of the watch glass (as a single-pane or multi-pane watch glass), a total light output of 67.5% can be achieved.

[0038] In the context of the invention, a multi-pane watch glass preferably means at least a two-pane watch glass.

[0039] In particular, a multi-layer watch glass can be equipped with: • a single coating on the inside of the carrier disc (no coating on the inside of the cover disc) • a multiple coating on the inside of the carrier disc (no coating on the inside of the cover disc) • a single coating on the inside of the cover disc (no coating on the inside of the carrier disc) • a single coating on the inside of the cover disc and a single coating on the inside of the carrier disc • a single coating on the inside of the cover disc and a multiple coating on the inside of the carrier disc • a multiple coating on the inside of the cover disc (no coating on the inside of the carrier disc) • a multiple coating on the inside of the cover disc and a single coating on the inside of the carrier disc • a multiple coating on the inside of the cover disc and a multiple coating on the inside of the carrier disc.

[0040] Advantageously, the cover disc can be a diamond disc with a Type Ila crystal structure (crystal lattice structure). In other words, the cover disc can be a Type Ila diamond. Type Ila is the purest carbon lattice type of diamond, i.e., with the fewest inclusions. Nitrogen inclusions, in particular, determine the diamond's color to a large extent. This is why a Type Ila diamond is the purest and most colorless diamond. Thus, a Type Ila diamond cover disc has the advantage that light can pass through the cover disc with the least interference, whereas a cover disc made from a different diamond type would potentially act as a color filter. Coloration (usually a yellowish hue) can have a negative impact on the freshness of a color (e.g., the background of the hands) and result in light loss.In particular, a watch glass with a cover plate made of monocrystalline, synthetic diamond of type Ila is a particularly preferred embodiment.

[0041] Diamond has certain cleavage planes where groups of crystal cells can be separated relatively easily. In relation to the essentially face-centered cubic crystal lattice cell ("unit cell" with mathematically eight carbon atoms) of diamond, there are certain planes that are usually described by three Miller indices. The relevant structural planes in the diamond crystal lattice are the three cube faces, which can be expressed by the Miller indices (100), (010), and (001).

[0042] Although diamond has a cubic basic structure, its natural crystallization form is octahedral. The cubic planes (100), (010), and (001) are the planes in the octahedron that connect four of the six vertices lying in a plane.

[0043] An octahedron has three possible planes, each connecting four of its vertices. In the cubic coordinate system, these are the planes represented by the Miller indices (100), (010), and (001). From a crystallographic perspective, all three planes are equivalent, since a cube or octahedron, which represents the diamond crystal structure, can be rotated in any direction and, regardless of the direction in which a cube or octahedron face is viewed, displays exactly the same atomic structure of the diamond crystal lattice.

[0044] A second crystal plane of the cubic diamond crystal lattice is the plane represented by three of the six possible diagonal planes in the cube, connecting four of the cube's eight vertices, and each of which contains a coordinate vector in the cube's coordinate system. These are the planes that can be expressed by the Miller indices (110), (101), and (011).

[0045] The prominent crystal planes (110), (101), and (011) in the octahedron are those planes that run parallel to one side of the octahedron, contain two vertices of the octahedron, and each penetrate four triangular octahedral faces as angle bisectors. Here, too, the three crystal planes (110), (101), and (011) are equivalent in the top view of the atomic lattice.

[0046] The third prominent crystal plane that plays a significant role in diamond is the plane that can be expressed in the cubic representation of the diamond crystal lattice by the Miller indices (111). This crystal lattice plane (111) is represented in the octahedron as an octahedral face. Here, too, all four possible octahedral face planes (there are four such planes, since two octahedral faces are parallel to each other) are equivalent in the schematic plan view of the atomic lattice.

[0047] In the diamond crystal lattice, which can be represented as planes by the coordinate vectors, there are three basic planes of the diamond, which in the octahedron represent the planes that • connect four corner points, (100) (001) (010) (referred to as 4-point planes in the diamond cutting industry) • or connect four angle bisectors (110) (101) (011) (referred to as 2-point planes in the diamond grinding industry) • or parallel to a surface of the octahedron (111) (referred to as 3-point planes in the diamond cutting industry)

[0048] The (111) plane, or the plane that runs parallel to one of the four possible octahedral faces (two of the eight octahedral faces are parallel) is the cleavage plane along which a monocrystalline diamond can be split very easily, or splits very easily under appropriate pressure.

[0049] Taking this into account, according to an advantageous embodiment, the cover plate can be a monocrystalline, synthetic diamond, wherein a surface of the cover plate runs either parallel to one of the crystallographic planes (100), (010), or (001), or parallel to one of the crystallographic planes (110), (101), (011). Thus, the surface of the cover plate runs at an oblique angle to the crystallographic plane (111) and simultaneously at an oblique angle to all three other, crystallographically identical, planes of the octahedral faces. The surface of the cover plate is, in particular, the outward-facing or inward-facing surface; in other words, the surface of the cover plate that faces or faces away from an interior of the watch, in particular a case of the watch, and / or at least one hand and / or a dial.The surface of the cover plate thus does not run perpendicular to the cleavage plane (111), thereby preventing the cover plate from breaking along the cleavage plane due to an impact on the watch glass. Furthermore, the surface does not run parallel to the cleavage plane (111). This prevents parallel cleavage when the watch glass bends due to pressure on the watch glass. If the watch glass bends, a radius of curvature of the bent watch glass would form. However, the radius of the curved surface of the watch glass facing towards a dial of the watch and / or an interior of the watch, in particular a case of the watch, and / or at least one hand of the watch would then be greater than the radius of curvature of the surface of the watch glass facing away from the watch.However, two different radii of curvature of the curved watch glass could potentially cause the various diamond layers to detach along the cleavage plane (111) if the cleavage plane were parallel to the surface of the diamond glass and thus at 90° to the bending radius, as enormous tensile forces could occur between the diamond layers, and these tensile forces would occur precisely along the cleavage plane. This design of the watch glass makes it possible to produce a particularly break-resistant cover plate and thus a particularly break-resistant watch glass, since on the one hand, the risk of the watch glass splitting along a parallel cleavage plane is eliminated, and on the other hand, bending of the watch glass itself is made more difficult and thus reduced by a more solid cover plate.

[0050] According to an advantageous embodiment, the cover plate can be made of polycrystalline diamond. The polycrystalline diamond can preferably have nanocrystalline diamond cells, in particular between 5 nm and 100 nm, or microcrystalline diamond cells, in particular larger than 100 nm, preferably larger than 20 µm. Such a configuration proves to be all the more advantageous the larger the individual polycrystalline diamond cells are. This is because the greater the number and the smaller the size of the individual diamond cells, the greater the optical impairment of the watch glass, in particular the so-called gray haze, due to light scattering caused by the structural change of the individual diamond cells.By increasing the size of the diamond cells and the associated reduction in their number, the optical impairment / gray haze caused by the diamond cells in the polycrystalline diamond is reduced. In particular, the optical impairment is minimized in a polycrystalline diamond with microcrystalline diamond cells, as this has the largest and therefore the fewest individual cells. The optical quality of a polycrystalline diamond, especially one with microcrystalline diamond cells, increases particularly with the duration of the growth process of the polycrystalline diamond, as the individual diamond cells become increasingly larger as they grow and gradually displace their smaller neighboring cells. Thus, as the growth time and the size of the individual diamond cells increase, the total number of individual cells present decreases.

[0051] When using a polycrystalline synthetic diamond as the cover plate, the nucleation side preferably forms the inside and the growth side forms the outside of the cover plate. In other words, the inside of the cover plate is created by the nucleation side of the grown diamond and the outside of the cover plate is created by the growth side of the grown diamond. The inside is the side of the cover plate that faces an interior of the watch, in particular a watch case, and / or at least one hand and / or a dial, wherein the outside is the side of the cover plate that faces away from the interior of the watch, in particular the watch case, and / or the at least one hand and / or the dial. Since the nucleation side has many more and much smaller diamond cells than the growth side, it is more flexible / elastic than the growth side.This allows the inner surface to bend more easily when the watch glass is subjected to pressure and better absorbs the tensile stress that occurs on the inside. The compressive stress that occurs on the outer surface of the cover plate when the watch glass is subjected to pressure is not as significant a problem for the cover plate because the diamond is very hard and pressure-resistant. The cover plate design described above allows the production of a particularly break-resistant polycrystalline, synthetic diamond and thus a particularly break-resistant cover plate.

[0052] Advantageously, the watch glass can have at least one decorative element, in particular a gemstone, arranged in a recess formed in the carrier disc. Preferably, the watch glass has a plurality of decorative elements, in particular gemstones, and a plurality of recesses. A decorative element is arranged in each recess. The number of recesses corresponds to the number of decorative elements.

[0053] Within the scope of the invention, the term "gemstone" advantageously means a stone, in particular a semiprecious stone or precious stone, that is faceted (i.e., not a rough stone). The gemstone can, in particular, be a diamond.

[0054] An upper region of the decorative element is preferably in direct contact with the connecting intermediate layer. Preferably, a region of the recess below a contact region of the decorative element with a wall of the recess comprises only air or a vacuum. In the case of a decorative element formed as a gemstone, the upper region preferably comprises a table facet and / or upper facets of the gemstone. Accordingly, in the case of a decorative element formed as a gemstone, a lower region of the decorative element comprises lower facets and / or preferably a tapered region of the gemstone.

[0055] The invention further relates to a method for producing a watch glass, in particular a watch glass as described above.

[0056] According to a first advantageous embodiment, the method comprises the steps of providing a substrate lying on a ground plane, growing a synthetic diamond blank on the substrate along a growth direction perpendicular to the ground plane, and cutting and / or grinding the diamond blank to produce the cover disk. The method further comprises bonding the cover disk to a layer formed as a carrier disk with a lower refractive index than the cover disk, and / or bonding the cover disk to at least one layer formed as a coating with a lower refractive index than the cover disk. The layer formed as a carrier disk preferably has a thickness greater than the wavelengths of visible light, preferably greater than 2 µm. The layer formed as a coating preferably has a thickness greater than the wavelengths of visible light, preferably greater than 2 µm.

[0057] Preferably, the method according to the first advantageous embodiment may include the step of bonding the outer side of the cover plate to a double layer comprising a diamond layer and an additional layer between the cover plate and the diamond layer. The additional layer has a lower refractive index than the cover plate and the diamond layer.

[0058] According to a second advantageous embodiment, the method comprises providing a substrate lying on a ground plane, growing a synthetic diamond blank on the substrate along a growth direction perpendicular to the ground plane, in particular by means of a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process, cutting and / or grinding the diamond blank to produce the cover plate, and bonding the outer side of the cover plate to a double layer comprising a diamond layer and an additional layer between the cover plate and the diamond layer. The additional layer has a lower refractive index than the cover plate and the diamond layer.

[0059] The following additional advantageous embodiments of the method described below relate both to the method according to the first advantageous embodiment and to the method according to the second advantageous embodiment.

[0060] The aforementioned growth of the synthetic diamond blank can be carried out in particular by means of a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process.

[0061] The method may further preferably comprise the step of separating the diamond blank from the substrate by cutting and / or grinding when using a substrate designed for heteroepitaxy or a substrate designed for homoepitaxy, in which the substrate itself consists of diamond, preferably of a polycrystalline, fragmented diamond layer.

[0062] The method may further preferably comprise the step of cutting the diamond blank perpendicular to the growth direction.

[0063] The method may further preferably comprise the step of cutting the diamond blank perpendicular to the growth direction into at least several usable cover disks or into at least one usable cover disk and at least one usable substrate.

[0064] The method may further preferably comprise the step of grinding the diamond blank in a plane perpendicular to the growth direction.

[0065] Advantageously, the diamond blank can be grown along the growth direction at a growth rate of less than 15 µm per hour, preferably less than 8 µm per hour, more preferably less than 5 µm per hour. This allows good purity and optical clarity of the grown diamonds and thus of the cover disk to be achieved. At a growth rate of less than 5 µm per hour, particularly high homogeneity and optical purity of the grown diamond can be achieved. In particular, growth rate here refers to the rate at which carbon atoms are deposed on a substrate during an MPCVD process. The growth rate can be accelerated or slowed by various factors.In particular, the negative pressure in the vacuum chamber in which the plasma ball is located, the frequency of the microwave generator, the temperature in the plasma ball, the exact height of the substrate plane or the "growth plane", possible additions of accelerating gases such as nitrogen, argon, oxygen, the ratio of hydrogen to methane and other factors can influence the growth rate of the grown diamond.

[0066] Advantageously, a substrate designed for heteroepitaxial growth can be used. This has the advantage that the substrate with the diamond layer can be easily removed from the machine once the desired thickness has been reached and ground down to create the cover plate. This allows, for example, a single-pane watch glass to be produced quickly. Furthermore, there is no need for an expensive substrate, no lossy separation of multiple panes, and there is virtually no risk of increasing defects during growth. Lasers and the provision of laser cutting machines for separating the panes are eliminated. Thus, the production of the watch glass using the heteroepitaxial process represents a very economical method.

[0067] According to a first alternative, a substrate with a large number of diamond particles can advantageously be used for homoepitaxy. However, according to a second alternative, a monocrystalline diamond can also be used as the substrate.

[0068] After growth, the diamond blank is preferably subjected to post-treatment with high pressure and / or high temperature to improve the color and / or final crystal structure. This makes it possible to achieve an improved color and / or an improved final crystal structure of the cover plate and thus of the watch glass. Furthermore, it is possible for large quantities of cover plates to have the same or a very similar color and / or final crystal structure. This is because the growth of monocrystalline and polycrystalline diamond layers creates synthetic diamonds that can vary in color and also exhibit irregularities in the diamond crystal lattice. The high pressure and / or high temperature exposes the diamond blank to the conditions under which a diamond normally crystallizes at a depth of approximately 110 kilometers below the Earth's surface.During this process, the diamond is allowed to excrete nitrogen and fully crystallize any incomplete crystallization sites. High pressure is preferably defined as a pressure between 45,000 atm and 60,000 atm. High temperature is preferably defined as a temperature between 1,250 degrees Celsius and 1,700 degrees Celsius.

[0069] Furthermore, the invention relates to the following methods according to embodiments 1 and 2, which can be used for producing a watch glass, in particular one of the watch glasses described above. Embodiment 1 shows a method for producing a diamond layer directly on the carrier disc and is preferably used if the cover disc is arranged directly on the carrier disc; this means in particular that none of the described layers, in particular no intermediate layer (lamination layer), no coating, and no anti-reflective coating, is present between the carrier disc and the cover disc. Embodiment 2 shows a method for producing a diamond disc that can be used for all of the watch glass options described above.

[0070] Thus, the invention shows a method for producing the watch glass (embodiment variant 1), comprising at least the following steps: (i) Providing a carrier disc made of glass, in particular quartz glass, which is transparent to visible light and has a metal film on its upper surface. The metal film can be described as catalytically functional. The carrier disc thus consists primarily of silicon oxide, although other materials can be added, for example, to modify the expansion coefficient—this will be described in more detail below. Preferably, the method also comprises applying the metal film to the upper surface of the carrier disc. (ii) Furthermore, the process involves growing a diamond layer as a cover disk on the upper side of the carrier disk by means of chemical vapor deposition, also known as a CVD process or chemical vapor deposition process. In particular, a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process is used. This process step is carried out, in particular, in a device for carrying out chemical vapor deposition.

[0071] The watch glass thus comprises the carrier disc and the diamond layer firmly attached to it.

[0072] The invention shows the ideal variant of a transparent, scratch-resistant watch glass as the direct combination of a carrier disc, which harmonizes with the diamond in terms of expansion coefficient, and a diamond layer made of synthetic diamond as a cover disc, applied directly to it using the CVD process.

[0073] Within the scope of the invention, it was recognized that a polycrystalline diamond layer, which is usually based on an initiation process using DND (detonation nanodiamonds), has the disadvantage of exhibiting extremely high optical scattering on the nucleation side, i.e., at the point of the diamond layer where the first randomly scattered diamond grains of very small size (5 nm to 40 nm) initiate the growth process. With an average size of 20 nm, 2 billion, 500 million diamond particles fit into one square millimeter. When this layer of individual crystals begins to grow in all possible directions using the CVD process, a "seed layer" is initially formed, which is highly fragmented and therefore not fully optically transparent.As the diamond layer grows, the number of nucleation cells decreases, as those diamond crystals growing perpendicular to the carrier wafer in a strong growth direction overtake and displace their sister cells. Thus, the situation improves with increasing layer thickness. The bottom layer, the nucleation side, would then have to be ground away to obtain a visually appealing product. However, when such a polycrystalline layer is grown directly onto a final substrate (carrier wafer according to the present invention), this nucleation layer cannot be removed, as it is grown directly onto the carrier wafer, which is intended to remain a component of the component.

[0074] Within the scope of the invention, it was recognized that a metal film on the upper side of the carrier disk enables the growth of an optically perfectly transparent diamond layer as a cover disk. This will be discussed in more detail below using a metal film made of nickel; however, these considerations also apply to a metal film made of copper, for example.

[0075] For diamond to grow using the CVD process, a crystallization nucleus, a so-called "seed," is first required that is similar to or identical to the diamond crystal lattice. These nuclei are typically made of diamond themselves. Diamond would not grow on pure quartz glass using the CVD process. For this purpose, the metal film is preferably impregnated with diamond powder and / or diamond-like nuclei.

[0076] Diamond has a face-centered cubic crystal lattice. Other materials also possess such a crystal lattice, such as silicon or some metals such as nickel and copper. However, for such a material to have a positive influence on diamond film growth, the unit cell of the face-centered cubic crystal lattice would have to be similar not only in structure but also in size to that of diamond. For example, the unit cell of silicon has a size of 5.43 Å (Ångstroms), while that of diamond has a size of 3.57 Å.

[0077] Since both nickel and silicon have a cubic unit cell in their crystal lattice, certain nickel-silicon compounds also have a cubic unit cell. The unit cell of Ni 3 Si is also very similar in size to that of diamond (3.506 Å).

[0078] In order to grow synthetic diamond onto a non-diamond substrate, very fine diamond powder is often used, which still retains the diamond's original crystal structure. DND (Detonation Nano Diamond) powder with a grain size of approximately 5 - 40 nm is usually used. This powder is created during the explosion of a TNT / RDX mixture in a sealed pressure chamber. However, there are also other processes for producing crystalline diamond powder. The method of producing diamond powder by grinding synthetic or natural diamond would not be particularly suitable for use as a seed cell, as this primarily produces fragments rather than intact diamond crystals. The fine diamond powder is then applied to the substrate using a suitable solvent, which has previously been thoroughly cleaned with acetone and various alcohols.There are various methods for this, such as the use of ultra-fine 3D printing systems, systems for applying lithographic layers to wafers for the semiconductor industry, etc. After the substrate has been impregnated, it is placed in a CVD reactor. In the plasma process, the diamond crystals grow in their typical crystal lattice structure by depositing carbon from methane gas. However, such a process for the production of transparent components would not lead to effective results without modification, as the optical quality would not meet the requirements of, for example, a high-quality watch glass. The high light scattering in a polycrystalline quartz glass substrate grown with synthetic diamond would produce such a strong gray haze in the diamond layer that the product would be unsuitable for a watch glass.

[0079] The present invention now proposes a modification of this process in that at least one film is installed between the carrier disk and the diamond layer as a cover disk, which film brings the completely diffuse polycrystalline character of the diamond growth layer into an ordered system with an orientation of the growth direction, which can ultimately be described as monocrystalline, or as "quasi-monocrystalline", which on the other hand bridge the problem of the different expansion coefficients of diamond and quartz glass and which, after fulfilling their task, optically disappear again or are / become invisible.

[0080] For example, nickel - but also copper or iridium - are ideal materials for this purpose, for the following reasons: (1) The crystal lattice structure of nickel, copper and iridium is also face-centered cubic like silicon and diamond. (2) The size of the unit cell, i.e., the basic atomic cell, of nickel and copper corresponds to that of the unit cell of diamond, with a deviation of only slightly more than 1%. The Ni unit cell has a size of 3.52 Å, that of diamond has a size of 3.57 Å, and that of copper 3.615 Å. Due to surface tension, the diamond crystals are deposited very densely and with a better-ordered crystal lattice orientation on the nickel or copper layer during the impregnation process (application of the diamond powder). It is advantageous for this to occur if the nickel or copper film has already been deposited in an orderly manner with the correct orientation on the carrier disk.

[0081] When nickel and copper layers are deposited as thin films on substrates that do not conform to the structure of pure nickel or copper, layers of these two materials tend to become structured in a subsequent "annealing" process. Various types of structures occur depending on the temperature, duration of the annealing process, and the substrate to which the layers are deposited. Face-centered cubic unit cells in an ordered orientation are the ideal structure for subsequent growth of monocrystalline diamond. However, fiber structures also occur in which individual groups of unit cells can reach up to 500 times the size of a single unit cell. Such structures are not suitable for our application.

[0082] In addition to the annealing process, there are other methods to induce the face-centered cubic structure of copper or nickel films in an ordered orientation, such as ion bombardment, BEN (Bias Enhanced Nucleation) methods, and others.

[0083] The first step is therefore in particular the application of a metal film (in particular of Ni or Cu or Ir), in particular by means of a sputtering process, e-beams, vapor deposition or another suitable process.

[0084] As a second step, an annealing process is advantageous, for example heating under a protective gas such as argon, usually with negative pressure, or another suitable process for the crystallographic structuring of the metal layer.

[0085] In particular, these two steps can also be combined into one by applying the metal film at a sufficiently high substrate temperature.

[0086] An ordered crystal structure of the metal film is a preferred prerequisite for the orientation of the growth direction of the diamonds during seeding with diamond crystals, for example, preferably in the (110) direction, which then corresponds to the (220) or (110) orientation in the case of nickel.

[0087] Diamond not only has exceptional hardness, but also a very high surface energy. A high surface energy means that a material has a strong tendency to attract other molecules. The surface energy varies depending on the crystallographic orientation of the surface of the diamond crystal lattice.

[0088] The varying surface energies according to the different orientation planes result in different cohesion values ​​for diamond. Nickel also has a high surface energy value. For nickel, this value also varies depending on the crystallographic orientation in the face-centered cubic crystal lattice.

[0089] If diamond nanocrystals are applied in the correct manner to a nickel substrate (metal film) which is crystallographically clearly oriented, then the diamond nanocrystals arrange themselves in such a way that certain orientation planes of the diamond crystals coincide with the corresponding orientation planes of the cubic nickel structure.

[0090] Nickel is a metal that, during the diamond growth process in the CVD chamber, bonds with the carrier disc (quartz glass) beneath the nickel under the influence of the plasma above the nickel layer and at temperatures between 700°C and 1150°C (preferably between 900°C and 1000°C). This means that at these high temperatures, nickel diffuses into the carrier disc and partially replaces silicon atoms, partially NiSi or NiSi. 2 -compounds, which in turn are ultimately absorbed and dissolved in the quartz glass.

[0091] This absorption of the nickel layer has several advantages. Firstly, the nickel layer disappears and is not visually disturbing. Although a very thin nickel layer would be barely visible to the naked eye, the opaque nickel would further intensify the component's gray haze. Secondly, the diffusion of nickel atoms into the quartz glass creates a type of "nickel glass" at the interface between the quartz glass and the diamond layer. The coefficient of thermal expansion of this layer is no longer 0.45 x 10 -6 K -1 as with pure quartz glass, but somewhat more. The expansion coefficient changes steadily from 0.45 x 10 -6 K -1 of pure quartz glass up to (ideally) 1.0 x 10 -6 K -1 at the interface between quartz glass and diamond. This marks the boundary between the expansion coefficient of diamond (1.0 x 10 -6 K -1) and quartz glass (0.45 x 10 -6 K -1 ) there is no longer a hard boundary at which a crack could develop between the two materials; instead, the stress is distributed in a thin boundary layer on the diamond side of the carrier disk. This makes a crack in the quartz glass or between quartz glass and diamond unlikely, since the stress between the various atomic layers is very small, less than the atomic bond between the individual atoms in the nickel-quartz glass.

[0092] In order to achieve the correct structuring of the continuously increasing expansion coefficient so that it is neither too low nor too high at the diamond boundary (for example, an expansion coefficient of 2 x 10 -6 K -1be too high), the thickness of the nickel layer, the temperature during the growth process, and the duration of the growth process should be coordinated accordingly. A longer growth process duration and a higher temperature during the growth of diamond result in stronger diffusion into the quartz glass and, once this diffusion has progressed to a certain extent, an excessively low coefficient of expansion at the interface. In contrast, a thicker nickel layer results in a higher coefficient of expansion at the interface. The three factors mentioned must therefore be balanced with one another in such a way that the adhesion of the diamond layer to the quartz glass is stronger than the tension due to two different coefficients of expansion.

[0093] The stress fields in quartz glass can be clearly visualized using polarizing filters. Stress fields in diamond can also be clearly identified using various instruments.

[0094] The risk of stress cracking is naturally greatest during the cooling of the quartz substrate with the diamond film deposited on it, as this involves a dramatic temperature change within a short period of time. However, stressed quartz glass also poses a long-term risk of cracking. The reason for this is the extreme susceptibility of glass, and quartz glass in particular, to microcracks. At some point, a microscopically small crack may develop in a stress zone. If the area surrounding this crack is under stress, the crack will grow over time, eventually merging with neighboring cracks, and in the long term (possibly even after years), lead to the flaking of the diamond layer.

[0095] From the above considerations and various experiments, the following features of the process have proven to be advantageous: Preferably, the metal film comprises nickel and / or copper and / or iridium. Preferably, the metal film consists of more than half, in particular entirely, of at least one of these metals. An alloy of two of these metals, in particular copper and nickel, has also proven advantageous for the metal film.

[0096] In addition to experiments, the following considerations also played a role in the selection of metals: Diamond: Unit cell with 3.57 angstroms; expansion coefficient: 1.0 x 10 -6 K -1 Nickel: unit cell with 3.52 Å and a difference to diamond of 0.05 angstroms; melting point: 1455 °C. Copper: Unit cell with 3.615 Å and a difference to diamond of 0.045 angstroms; melting point: 1083 °C. Iridium: Unit cell with 3.833 Å and a difference to diamond of 0.26 Å; melting point: 2446 °C.

[0097] The high melting point of iridium makes it difficult to anneal a thin iridium film on the surface of quartz glass in the same way as copper or nickel, since the melting point of quartz glass is significantly lower. Therefore, different mechanisms for aligning the crystal lattice than for nickel or copper, or for the orderly growth of diamond on the iridium substrate, must be used for iridium, e.g., ion bombardment, a BEN (bias-enhanced nucleation) process, etc. Alternatively, a slightly modified annealing procedure may be required.

[0098] Iridium isn't exactly excellent in terms of unit cell size compared to diamond (3.833 Å). Nevertheless, good results have been achieved with iridium.

[0099] A metal film made of nickel or copper is particularly suitable for growth on quartz glass, since the size of the unit cell of the face-centered cubic crystal structure is very similar to that of diamond.

[0100] A Cu-Ni alloy is also preferably used as the metal film; in particular, with a deviation of the size of the cubic unit cell of only 0.025 Angstroms compared to the size of the cubic unit cell of diamond.

[0101] Since the metal film is supposed to diffuse into the quartz glass after the first crystallization of diamond and thus dissolve, pure copper is particularly preferred because of the materials mentioned it has the highest diffusion coefficient in quartz glass.

[0102] Preferably, the metal film has a thickness of at most 30 nm, preferably at most 20 nm, and more preferably at most 10 nm, prior to diamond growth; preferably, the metal film has a thickness of at least 2 nm. During growth, the metal film can partially or completely diffuse into the carrier disk and thus at least partially disappear. The small thickness of the metal film ensures that the entire component remains transparent, even if the metal film does not completely diffuse in.

[0103] It is preferably provided that the diamond layer as a cover plate has a thickness of at least 30µm and / or a maximum of 2mm after growth.

[0104] Preferably, the carrier disc has an expansion coefficient of 0.45 x 10 -6 K -1 up to 1.2 × 10 -6 K -1 , preferably 0.8 x 10 -6 K -1up to 1.2 × 10 -6 K -1 , has.

[0105] Quartz glass, the preferred material for the carrier disc, has an expansion coefficient of 0.45 × 10 -6 K -1 , synthetic diamond has an expansion coefficient of 1.0 x 10 -6 K -1The two materials therefore fit together reasonably well. Nevertheless, growing a thick diamond layer as a cover plate directly onto quartz glass could lead to stresses, because neither quartz glass nor synthetic diamond are very elastic and can compensate for differential expansion. In particular, the CVD process operates at temperatures of 925°C to 950°C. Upon cooling from such temperatures to room temperature, a directly bonded two-layer quartz-diamond glass could shatter. Therefore, a certain buffer between the two layers, or a modification of the quartz glass at least at the interface, is advantageous.

[0106] Preferably, the expansion coefficient is adjusted by using a doped quartz glass carrier disk, which is as close as possible to the expansion coefficient of synthetic diamond. This is possible, for example, based on the following considerations: Quartz is the basic material for glass. In the extremely numerous varieties of glass, some of the silicon atoms are usually replaced by atoms of one or more other elements. For example, a good lead crystal glass consists of up to 75% lead oxide, a good silver crystal glass of up to 50% silver oxide, etc. Glass can absorb many metals by replacing silicon atoms with foreign atoms. In this case, the coefficient of expansion changes and, in most cases, becomes larger. Most types of glass have a coefficient of expansion of between 6 x 10 -6 K -1 up to 9 x 10 -6 K -1, i.e., 12 to 20 times the expansion coefficient of quartz glass. It can be seen that by deliberately adding lead oxide or silver, for example, the expansion coefficient of the carrier disc can be reduced to approximately 1 x 10 -6 K -1 can be set.

[0107] Preferably, the metal film is applied by vapor deposition, cathode sputtering, electron beam evaporation, or an electrolytic process. The metal film should be applied to the carrier disk with as uniform a thickness as possible.

[0108] Preferably, the metal film is brought into a defined crystallographic orientation by annealing during or after application.

[0109] Preferably, prior to growth, a diamond powder is applied to the metal film, in particular with a grain size of 5 nm to 40 nm. In particular, this is carried out by the following steps: applying a mixture of a liquid with diamond powder to the metal film and removing the liquid, in particular by centrifugation and / or evaporation.

[0110] It is preferably provided that the metal film is at least partially diffused into the carrier disk by thermal action before and / or during the chemical vapor deposition.

[0111] It is preferably provided that an additional film of mineral material, preferably with silicon or synthetic material, is located between the metal film and the carrier disk before growth.

[0112] It is preferably provided that the additional film has a thickness of at most 30 nm, preferably at most 20 nm, more preferably at most 10 nm.

[0113] The process for producing a diamond disc (version 2) comprises the following steps, whereby the above considerations also apply to this process: (i) Providing a substrate of preferably pure, crystalline silicon with a metal film on top. Preferably, the method also comprises applying the metal film to the top of the substrate. Since silicon already has a face-centered cubic crystal structure, the crystallographic alignment of a metal film on the silicon wafer preferably does not follow the same process as the annealing of a metal film on quartz glass. Here, the nickel or copper is preferably deposited in the appropriate cubic structure during the application of the metal film to the silicon. (ii) Furthermore, the process involves growing a diamond disk by means of chemical vapor deposition, also known as a CVD process or chemical vapor deposition process. In particular, a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process is used. This process step is carried out, in particular, in a device for carrying out chemical vapor deposition. (iii) After growth, the substrate is removed from the diamond disk.

[0114] Preferably, the method for producing the diamond disc provides for a semiconductor wafer to be used as the substrate.

[0115] Preferably, the process for producing the diamond disc uses a metal film made of nickel and / or copper and / or iridium. Preferably, the metal film consists of more than half, in particular entirely, of at least one of these metals. An alloy of copper and nickel has also proven advantageous for the metal film.

[0116] Preferably, the method for producing the diamond disk provides for the metal film to have a maximum thickness of 30 nm, preferably a maximum of 20 nm, more preferably a maximum of 10 nm, prior to growth; preferably wherein the metal film has a thickness of at least 2 nm. During the process, the metal reacts with the silicon substrate and diffuses partially or completely into the substrate, thus at least partially disappearing. This process has certain advantages in that, for example, silicon-nickel compounds are formed, which push back the polycrystalline carbon formations during the diamond growth process or can assist in the dissolution of unwanted non-diamond deposits with the aid of hydrogen gas.

[0117] Preferably, the method for producing the diamond disc provides that the diamond disc has a thickness of at least 30µm and / or a maximum of 2mm after growth.

[0118] Preferably, the method for producing the diamond disc provides that the metal film is applied by vapor deposition or cathode sputtering or electron beam evaporation or an electrolytic process.

[0119] Preferably, the method for producing the diamond disk includes applying diamond powder to the metal film prior to growth. In particular, this is done by applying a mixture of a liquid with diamond powder to the metal film, and removing the liquid, in particular by centrifugation and / or evaporation.

[0120] Furthermore, the invention relates to a watch, in particular a wristwatch, comprising a case and a watch glass arranged on the case according to the previous description of the watch glass and / or manufactured according to one of the previously described methods.

[0121] The invention also relates to a watch, in particular a wristwatch, comprising a case and a watch crystal arranged on the case. The watch crystal here consists of diamond / is made of diamond, in particular exclusively of diamond without any additional layer. When the watch crystal is made exclusively of diamond, the watch crystal has only one diamond disc. This disc can advantageously have the features (individually or in combination) of the cover disc described above.

[0122] It is to be understood that in the above-mentioned embodiments or in the embodiments according to the claims, the person skilled in the art would select the different features, in particular the absolute dimensions, especially the thickness, of the different components of the watch glass in such a way as to result in technically sensible combinations.

[0123] Further details, advantages, and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows: Fig. 1 is a schematic simplified plan view of a watch glass according to a first embodiment of the present invention, Fig. 2 a schematic simplified sectional view of the watch glass according to the first embodiment, Fig. 3 a schematic simplified sectional view of the watch glass according to a second embodiment of the present invention, Fig. 4 is a schematic simplified sectional view of the watch glass according to a third embodiment of the present invention, Fig. 5 is a schematic simplified sectional view of a coating that can be used in the watch glass according to the first, second and third embodiments, Fig. 6 is a schematic simplified sectional view of the watch glass according to a fourth embodiment of the present invention, Fig. 7 a simplified schematic representation of the diamond lattice structure as a face-centered cubic lattice structure, Fig. 8 a schematic simplified representation of the diamond crystal structure as a regular cube, Fig. 9 a schematic simplified representation of the diamond crystal structure as a regular cube, Fig. 10 a simplified representation of the diamond crystal structure in its natural crystallization form, Fig. 11 is a simplified representation of a manufacturing process of a diamond from which a cover plate of the watch glass can be made according to the first, second, third or fourth embodiment, Fig. 12 is a schematic simplified sectional view of a watch with a watch glass according to the first, second, third or fourth embodiment of the invention, Fig. 13 a cleavage mode of a diamond disc, Fig. 14 another cleavage mode of a diamond disc, and Fig. 15 a schematic simplified sectional view of the watch glass according to a fifth embodiment of the present invention Fig. 16 to 23 show a schematic view of the course of a method according to the invention for producing a diamond disk by growing it on a silicon substrate for the above-mentioned embodiment variant 2.

[0124] The following is based on the Fig. 1 and Fig. 2 a watch glass 1 according to a first embodiment of the present invention is described in detail.

[0125] As can be seen from Fig. 1, the watch glass 1 is circular. In particular, the watch glass 1 can have a diameter of 40 mm. However, other shapes for the watch glass 1 than the circular shape are also possible.

[0126] Out of Fig. 2 that the watch glass 1 is a single-pane watch glass and comprises (only) a cover plate 4 and a layer formed as a coating 5 (a single layer formed as a coating 5 or, in other words, a single coating 5). The cover plate 4 is made exclusively of diamond. In particular, the cover plate 4 can be made of polycrystalline, synthetic diamond or monocrystalline, synthetic diamond. However, it is also conceivable for the cover plate 4 to be made of natural diamond. The design of the cover plate 4 exclusively from diamond has the advantage that it is 100% scratch-resistant and has a high-quality flair.

[0127] The coating 5 is applied to an inner side 3 of the cover plate 4. With reference to Fig. 12, which shows a watch 40 designed as a wristwatch with a case 41, a strap 43, a dial 44, and at least one hand 42 for indicating the time, the inner side 3 of the cover plate 4 is the side of the cover plate 4 that faces an interior 410 of the case 41, the at least one hand 42, and the dial 44. "Facing" means that the inner side 3 of the cover plate 4 is closer to the interior 410 of the case 41, the at least one hand 42, and the dial 44 than an outer side 2 of the cover plate 4. The outer side 2 faces away from the interior 410 of the case 41, the at least one hand 42, and the dial 44.

[0128] The coating 5 has a thickness 501 significantly greater than the wavelengths of visible light. Such a thickness 501 of the coating 5 has the advantage that no interference effects occur in the coating 5 when light passes through the watch glass 1.

[0129] The coating 5 extends over 100% of the surface, i.e., over the entire surface of the cover plate 4 on its inner side 3. In particular, the coating 5 is arranged over the entire surface of the cover plate 4. However, it is also possible, particularly if the coating 5 is produced by means of PVD, for it not to be arranged over the entire surface of the inner side 3 of the cover plate 4. In this alternative embodiment, the coating 5 does not extend to the edge of the watch glass 1, i.e., in particular, of the cover plate 4, or ends before the edge of the watch glass 1.

[0130] The cover plate 4 can have a thickness 502 of at least 0.1 mm, preferably at least 0.3 mm, more preferably at least 0.5 mm, preferably at least 0.75 mm, preferably at least 1 mm. Preferably, the thickness is less than or equal to 0.5 mm. Particularly preferably, the thickness 502 of the cover plate 4 can be between 0.3 mm and 0.6 mm, preferably between 0.3 mm and 0.5 mm. This allows the optical advantages described in the general section to be achieved.

[0131] In particular, the cover plate 4 can be a diamond with a crystal structure (crystal lattice structure) of type IIa. In other words, the cover plate 4 can be a type IIa diamond. Thus, the cover plate 4 has the advantage that the light can pass through the cover plate 4 with the least interference.

[0132] The following refers to the Fig. 7 to 10 to explain further features of the watch glass 1.

[0133] In Fig. 7 shows the essentially cubic face-centered crystal lattice cell of diamond (“unit-cell” with calculated 8 carbon atoms). Fig. 8 and Fig. 9, the diamond crystal structure is shown as a regular cube with certain planes (hatched planes), where in Fig. 10 octahedral structures with specific planes labeled (hatched planes) are shown. The octahedral structure is the structure that diamond exhibits in its natural crystallization form.

[0134] Diamond has certain cleavage planes in which groups of crystal cells can be separated relatively easily. Related to the cubic crystal lattice cell according to Fig. 7, there are certain planes that are usually described by Miller indices. The relevant structural planes in the diamond crystal lattice are, first of all, the three cube faces, which can be expressed by the Miller indices (100), (010), and (001).

[0135] In its natural crystallization form, the cubic planes (100), (010) and (001) can be identified as those planes in the octahedron which connect four of the eight corners lying in a plane in the octahedron.

[0136] An octahedron has three possible planes, each connecting four of its vertices. In the cubic coordinate system, these are the planes expressed by the Miller indices (100), (010), and (001). From a crystallographic perspective, all three planes are equivalent, since a cube or octahedron, which represents the diamond crystal structure, can be rotated in any direction and, regardless of the direction in which a cube or octahedron face is viewed, reveals exactly the same atomic structure of the diamond crystal lattice.

[0137] A second crystal plane of the cubic diamond crystal lattice, which occurs in diamond, is the plane represented by three of the six possible diagonal planes in the cube, which connect four of the cube's eight vertices, and in which a coordinate vector lies in the representation of the coordinate system. These are the planes that can be expressed by the Miller indices (110), (101), and (011).

[0138] The prominent crystal planes (110), (101), and (011) in the octahedron are those planes that run parallel to one side of the octahedron, contain two vertices of the octahedron, and each penetrate four triangular octahedral faces as angle bisectors. Here, too, the three crystal planes (110), (101), and (011) are equivalent in the top view of the atomic lattice.

[0139] The third prominent crystal plane that plays a significant role in diamond is the plane that can be expressed in the cubic representation of the diamond crystal lattice by the Miller indices (111). This crystal lattice plane (111) is represented in the octahedron as an octahedral face. Here, too, all four possible octahedral face planes (there are four such planes, since two octahedral faces are parallel to each other) are equivalent in the schematic plan view of the atomic lattice.

[0140] In the diamond crystal lattice, which can be represented as planes by the coordinate vectors, there are three basic planes of the diamond, which in the octahedron represent the planes that • connect four corner points: Levels (100) (001) (010) according to Fig. 8 • or connect four angle bisectors: planes (110) (101) (011) according to Fig. 9 • or parallel to a surface of the octahedron: plane (111) according to Fig. 10

[0141] The (111) plane, or the plane that runs parallel to one of the four possible octahedral faces (two of the eight octahedral faces are parallel) is the cleavage plane along which a monocrystalline diamond can be split very easily, or splits very easily under appropriate pressure.

[0142] Taking this into account, a surface of the cover plate 4, if it is made of monocrystalline diamond, can run either parallel to one of the crystallographic planes (100), (010), or (001), or parallel to one of the crystallographic planes (110), (101), (011). Thus, the surface of the cover plate 4 runs at an oblique angle to the crystallographic plane (111) and simultaneously at an oblique angle to all three other, crystallographically identical, planes of the octahedral faces. The surface of the cover plate 4 is, in particular, the outward- or inward-facing surface; in other words, the surface of the cover plate 4 that faces or faces away from the interior 410 of the case 41 of the watch 40, the at least one hand 42, and the dial 44.The surface of the cover plate 4 is therefore not perpendicular to the cleavage plane (111), which can prevent the cover plate from breaking along the cleavage plane due to an impact on the watch glass 1. Such a break is shown in . Fig. 13. Furthermore, the surface is not parallel to the cleavage plane (111). Running the surface parallel to the cleavage plane (111) could also lead to a fracture according to Fig. 14 lead.

[0143] This makes the cover plate 4, and thus also the watch glass 1, particularly break-resistant. If the cover plate 4 is made of polycrystalline diamond, the polycrystalline diamond can have nanocrystalline diamond cells (>5 nm, <100 nm) or microcrystalline diamond cells (>100 nm), preferably larger than 20 µm. Larger diamond cells have the advantage of reducing optical impairment of the watch glass 1, in particular the so-called gray haze (due to light scattering), which is normally caused by the diamond cells of the polycrystalline diamond.

[0144] In particular, when using a polycrystalline synthetic diamond as the cover plate 4, the nucleation side forms the inner side 3 and the growth side forms the outer side 2 of the cover plate 4. Thus, the inner side 3 can bend more easily when the watch glass 1 is subjected to compressive stress and can better absorb the tensile stress occurring on the inner side 3. The compressive stress occurring on the outer side 2 when the watch glass 1 is subjected to compressive stress poses less of a problem for the cover plate 4 because the diamond is very hard and pressure-resistant. The described design of the cover plate 4 makes it possible to achieve a particularly fracture-resistant polycrystalline, synthetic diamond and thus a particularly fracture-resistant cover plate.

[0145] According to a modification of the watch glass 1 of the first embodiment, the watch glass 1 may be made entirely of diamond without any additional layer. That is, the modified watch glass 1 does not have the coating 5, but only the cover plate 4.

[0146] Fig. 3 shows a watch glass 1 according to a second embodiment of the present invention.

[0147] The watch glass 1 according to the second exemplary embodiment differs from the watch glass 1 according to the first exemplary embodiment in that the watch glass 1 according to the second exemplary embodiment is designed as a multi-pane watch glass, in particular a two-pane watch glass. This means that the watch glass 1 according to the second exemplary embodiment comprises, in addition to the cover plate 4, a layer designed as a carrier plate 6 which is firmly connected to the cover plate 4. Secondly, the watch glass 1 according to the second exemplary embodiment, in contrast to the watch glass 1 according to the first exemplary embodiment, does not have a layer designed as a coating 5 on the inner side 3 of the cover plate 4. However, such a coating 5 is also possible for the watch glass 1 according to the second exemplary embodiment.

[0148] To connect the cover plate 4 to the carrier plate 6, the watch glass 1 comprises an intermediate layer 7 between the cover plate 4 and the carrier plate 6. The production of the watch glass 1 with the intermediate layer 7 between the cover plate 4 and the carrier plate 6, i.e. in other words the production of the watch glass 1 as laminated composite glass, enables a particularly high level of break resistance of the watch glass 1, since in the event of an impact on the watch glass 1, the impact energy can be absorbed by the cover plate 4 via the intermediate layer 7 and also by the carrier plate 6. Furthermore, the laminating of the cover plate 4 to the carrier plate 6 is a cost-effective process. Furthermore, the provision of the connecting intermediate layer 7 results in the optical appearance of the watch glass 1 being improved.In particular, the light balance of the watch glass 1 is improved because the difference in refractive index between the corresponding optical media (diamond intermediate layer) at the interface between the cover plate 4 and the intermediate layer 7 is smaller than the difference in refractive index between diamond and air.

[0149] The intermediate layer 7 can, in particular, be thinner than the cover plate 4 and / or than the carrier plate 6. However, it is also possible for the intermediate layer 7 to be thicker than the cover plate 4.

[0150] In particular, the intermediate layer 7 can have a thickness 504 between 0.1 mm and 0.3 mm. In particular, the thickness 503 of the carrier disk 6 can be at least 0.3 mm, preferably at least 0.5 mm, more preferably at least 1 mm, more preferably at least 1.5 mm. Furthermore, the carrier disk 6 can be thicker than the cover disk 4.

[0151] Furthermore, the intermediate layer 7 can consist of at least one cured adhesive layer, preferably of a cured UV adhesive, or of at least one laminating layer made of / with EVA, PVB, Sentry Glass or another laminating film.

[0152] Furthermore, the intermediate layer 7 can have a refractive index of up to + / - Δn=0.4, preferably up to + / - Δn=0.2, but preferably equal to the refractive index of the carrier disc 6. "Δn" stands for the difference between the refractive index of the intermediate layer 7 and the refractive index of the carrier disc 6. Due to the very similar refractive indices of the intermediate layer 7 and the carrier disc 6, a reflection loss at the interface between these components of the watch glass 1 and thus the overall reflection loss in the watch glass 1 can be further reduced. In particular, the intermediate layer can have a refractive index between 1.4 and 1.6, in particular 1.48.

[0153] The carrier disc 6 is advantageously made of a different material than the cover disc 4, ie the carrier disc 6 is not made of diamond. In particular, the carrier disc can be made of glass, in particular of a glass with an expansion coefficient between 0.001 x 10 -6 K -1 and 2 × 10 -6 K -1 , in particular from quartz glass or from Sitall or Vycor or Zerodur or Cer Vit or from plastic or from sapphire glass. Thus, a stable connection between the cover plate 4 and the carrier plate 6 can be achieved in the event of ambient temperature changes and / or when the cover plate 4 is laminated to the carrier plate 6 by heating. The carrier plate 6 is particularly preferably made, in particular exclusively, of quartz glass.

[0154] Out of Fig. 3 further shows that the watch glass 1 comprises a plurality of decorative elements 10 and a plurality of recesses 9. The number of decorative elements 10 is equal to the number of recesses 9. The decorative elements 10 are gemstones, in particular diamonds. Here, the recesses 9 are formed in the carrier disc 6. Exactly one decorative element 10 is arranged in each recess 9.

[0155] Each decorative element 10 is arranged in the corresponding recess 9 such that an upper region of the decorative element 10 is in direct contact with the connecting intermediate layer 7, and a region of the recess 9 below a contact area of ​​the decorative element 10 with a wall of the recess 9 contains only air or a vacuum. Here, the upper region of the respective decorative element comprises a table facet and the top facets of the gemstone. This allows a high-quality appearance of the decorative elements 10 to be achieved.

[0156] Fig. 4 shows a watch glass 1 according to a third embodiment of the present invention.

[0157] The watch glass 1 according to the third embodiment differs from the watch glass 1 according to the second embodiment in that the watch glass 1 according to the third embodiment comprises a plurality of layers formed as coatings 5.

[0158] In particular, the watch glass 1 comprises a first coating 5 (a first layer formed as coating 5) between the cover plate 4 and the intermediate layer 7, which is arranged on the inner side 3 of the cover plate 4. Furthermore, the watch glass 1 comprises a second coating 5 (a second layer formed as coating 5) between the intermediate layer 7 and the carrier plate 6, which is arranged on the side of the carrier plate 6 facing the intermediate layer 7. A third coating 5 (a third layer formed as coating 5) is applied to a side of the carrier plate 6 facing the interior 410 of the case 41 of the watch 40.

[0159] In particular, the coatings 5 ​​have a gradually lower refractive index from the outside to the inside, ie, in the direction from the cover plate 4 to the carrier plate 6.

[0160] Fig. 5 shows a layer formed as coating 5, which is formed as a multiple coating.

[0161] As such, the coating 5 comprises several superimposed coating layers 5a made of the same or different materials. Preferably, the coating layers 5a have a progressively lower refractive index from the outside to the inside. Thus, the continuously graded refractive indices of the coating layers 5a can significantly reduce the reflection loss that would otherwise occur in a watch glass 1 without a coating 5 at the transition between the cover plate 4, in particular the inner side 3 of the cover plate 4, and air.

[0162] A lower refractive index from the outside to the inside, ie in the direction from the cover plate 4 to the carrier plate 6, means that in the mounted state of the watch glass 1 in the watch 40, a coating plane 5a which, in comparison to another coating plane 5a, faces the interior 410 of the housing 41, has a lower refractive index than the other coating plane 5a.

[0163] As already described, the coating 5 on the watch glass 1 can be Fig. 2 according to the first embodiment may be a multiple coating, such as the coating of Fig. 5. However, it is also possible that the coating 5 on the watch glass 1 is Fig. 2 according to the first embodiment is a single coating.

[0164] Fig. 6 shows a watch glass 1 according to a fourth embodiment of the present invention.

[0165] The watch glass 1 according to the fourth embodiment differs from the watch glass 1 according to the second embodiment in that the watch glass 1 according to the third embodiment comprises a plurality of layers formed as anti-reflective coatings 8. The anti-reflective coatings 8 can each be single-layered or multi-layered.

[0166] In particular, a first anti-reflective coating 8 is applied to the inner side 3 of the cover plate 4. A second anti-reflective coating 8 is applied to an inner side of the intermediate layer 7 between the cover plate 4 and the carrier plate 6, and a third anti-reflective coating 8 is applied to the side of the carrier plate 6 facing the interior 410 of the case 41 of the watch 40.

[0167] The anti-reflective coatings 8 can reduce reflection losses when the light emerges from the respective medium to which they are attached, thus increasing the light output.

[0168] With reference to Fig. 11 shows a method for producing a watch glass 1 according to one of the previously described embodiments. In particular, Fig. 11 the production of a synthetic diamond from which the cover plate 4 of the watch glasses 1 of the previous embodiments is made.

[0169] The method first comprises providing a substrate 31 (seed) lying on a base plane 30. Furthermore, the method comprises growing a synthetic diamond blank 32 on the substrate 31 along a growth direction 33 perpendicular to the base plane 30. The synthetic diamond blank 32 can be grown, in particular, by means of a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process. In this case, the diamond blank 32 can be grown along the growth direction 33 at a growth rate of less than 15 µm per hour, preferably less than 8 µm per hour, more preferably less than 5 µm per hour. Thus, good purity and optical clarity of the grown diamonds and thus of the cover plate 4 can be achieved.At a growth rate of less than 5 µm per hour along the growth direction 33, a particularly high homogeneity and optical purity of the grown diamond can be achieved. Thus, a particularly homogeneous and optically pure cover plate 4 can be produced.

[0170] The synthetic diamond blank 32 is cut and / or ground to produce the cover plate 4. In particular, the diamond blank 32 can be cut perpendicular to the growth direction 33 and / or ground in a plane perpendicular to the growth direction 33. By cutting the diamond blank 32 perpendicular to the growth direction 33, it can be cut into at least several usable cover plates 4 for several watch glasses 1. Alternatively, the diamond blank 32 can be cut into at least one usable cover plate 4 for one watch glass 1 or several watch glasses 1 and at least one usable substrate 31, which can then be used to grow another diamond.

[0171] In particular, the synthetic diamond blank 32 can be cut and / or ground from the substrate 31 if the substrate 31 is a substrate designed for heteroepitaxy, or a substrate designed for homoepitaxy, in which the substrate 31 itself does not consist of diamond or of a polycrystalline, fragmented diamond layer.

[0172] According to an alternative advantageous embodiment of the invention, a substrate comprising a plurality of diamond particles can be used for homoepitaxy. It is also possible to use a monocrystalline diamond as the substrate 31.

[0173] After growth, the diamond blank 32 is preferably subjected to a post-treatment with high pressure, in particular with a pressure between 45,000 atm and 60,000 atm, and / or high temperature to achieve an improvement in the color and / or the final crystal structure. High pressure is understood to mean, in particular, a pressure between 45,000 and 60,000 atm. High temperature is preferably understood to mean a temperature between 1,250 degrees Celsius and 1,700 degrees Celsius.

[0174] Depending on the design of the watch glass 1, the produced cover plate 4 is bonded to the previously described layer or layers of the watch glass 1 if the watch glass 1 comprises a plurality of layers. Thus, to produce the watch glass 1 according to the first exemplary embodiment, after the cover plate 4 has been produced, the coating 5 is applied to the inner side 4 of the cover plate 4. To produce the watch glass 1 according to the third exemplary embodiment, after the cover plate 4 has been produced, the corresponding coating 5 is applied to the inner side 3 of the cover plate 4. Furthermore, the other two coatings 5 ​​are applied to the carrier plate 6. Once the cover plate 4 and the carrier plate 6 are coated, they are bonded to one another by means of the intermediate layer 7.To produce the watch glass 1 according to the fourth embodiment, the anti-reflective coatings 8 are applied to the produced cover plate 4 and the carrier plate 6 and then the cover plate 4 and the carrier plate 6 are connected to one another by means of the intermediate layer 7.

[0175] Fig. 15 shows a watch glass 1 according to a fifth embodiment of the present invention.

[0176] The watch glass 1 according to the fifth embodiment comprises, in addition to the cover plate 4 made of diamond, a double layer 11 on the outer side 2 of the cover plate 4. The double layer 11 has a diamond layer 12 and an additional layer 13 between the cover plate 4 and the diamond layer 12. The additional layer 13 has a lower refractive index than the cover plate 4 and the diamond layer 12.

[0177] The additional layer 13 is formed from a dielectric material. The refractive index and thickness of the additional layer 13 and the thickness of the diamond layer 12 are selected such that the reflections at the boundary transitions between the additional layer 13 and the diamond layer 12 are at least partially, in particular completely, compensated outward, i.e., in the direction away from the watch.

[0178] After the cover plate 4 has been manufactured according to the method described above, the outer side 2 of the cover plate 4 is bonded to the double layer 11. In particular, the additional layer 13 is applied to the cover plate 4 or to its outer side 2. The diamond layer 12 is then applied to the additional layer 13, so that in the finished watch glass 1, the additional layer 13 is arranged between the cover plate 4 and the diamond layer 12.

[0179] Fig. 16 to 23 show a schematic view of the process according to the invention for producing a diamond disk by growth on a silicon substrate, in particular for embodiment variant 2.

[0180] First, the CVD reactor 1001, as a device for carrying out chemical vapor deposition, is equipped with the silicon substrate 1002 including the applied metal film 1003; e.g., a nickel layer of either 5 nm or 10 nm thickness, on which a layer of diamond crystals 1004 with a grain size of 5 nm to 40 nm is applied. The diamond crystals 1004 are preferably DND (Detonation Nano Diamond) crystals, but can also be produced by a process other than detonation. The high surface energy of the nickel and the diamonds results in a uniform and dense distribution of the diamond crystals on the nickel film. The same applies to copper. For the sake of clarity, the CVD reactor 1001 is only shown in Fig. 16 shown.

[0181] A standard MPCVD reactor (microwave plasma chemical vapor deposition reactor) can be used as a CVD reactor 1001. An HFCVD reactor (hot filament chemical vapor deposition reactor) is also suitable. Advanced reactors that use additional means (such as laser or ion bombardment) to deliver energy to the diamond growth plane are also suitable.

[0182] Fig. 16: First, we evacuate the reactor chamber of the CVD reactor 1001 to remove all atmospheric gases from the reactor chamber. Then, while slowly increasing the temperature, we flood the chamber first with hydrogen, the process gas, and then with methane, the carrier of the carbon we want to deposit as diamond on the substrate. The ratio of hydrogen to methane is approximately 10 / 1. The flow rate of the hydrogen is approximately 400 sccm and that of the methane approximately 40 sccm, but a different flow rate and a different ratio of H 2 and CH 4 We initially keep the pressure in the reactor chamber at a very low level of approximately 25 Torr. Over the course of the process, however, we increase the pressure to up to 135 Torr.

[0183] Fig. 17: When we reach 200 °C during temperature ramp-up, the diamond crystals do not yet grow, but the nickel slowly begins to diffuse into the silicon of the substrate 1002 and starts to form a nickel-silicon interlayer 1005 made of nickel-silicon.

[0184] During the next operating time of the first hour, ( Fig. 18) From 400°C, polycrystalline non-diamond carbon (carbon 1006) forms between the individual seed cells (diamond crystals 1004). However, this is broken down by the process hydrogen and converted by the plasma into methane or other hydrogen-carbon gases. Fig. 19), carbon 1006 also diffuses into the nickel-silicon interlayer 1005, or diffuses out again. The diamond crystals 1004, which are initially arranged in a jumbled pattern, slowly begin to grow. They grow preferentially in the (110) orientation or the (100) orientation. Since the (110) oriented crystals 4 grow somewhat faster than those in other directions, a nearly uniform growth orientation soon forms.

[0185] Fig. 20: At a temperature of 750 °C, a polycrystalline layer 1007 of non-diamond carbon (carbon 1006) initially forms on the diamond crystals 1004, but this layer regresses at an even higher temperature.

[0186] Fig. 21: By absorbing carbon from the methane gas, we obtain a growth structure in which the fast-growing crystals take away the energy and methane gas from the slow-growing crystals and overgrow them.

[0187] Fig. 22 and Fig. 23: With further growth, a more or less uniform layer of fast-growing diamond crystals 1004 is formed, all of which grow upwards in the same orientation.

[0188] Small silicon-nickel particles of the 1008 type or polycrystalline black carbon may be deposited in the interface layer, but these particles are so small that they are below the limit of visibility to the naked eye. The nickel layer has now almost or completely disappeared, and all the nickel has diffused into the silicon substrate.

[0189] While after 2 to 3.5 hours we still have about 10 to 15% of the diamond in the orientation (111), after about 10 hours the ratio of diamond in the orientation (110) to diamond in the orientation (111) is already almost 95% to 5%.

[0190] We can now speak of a monocrystalline or “quasi-monocrystalline” diamond layer or diamond disc.

[0191] Chemically speaking, the following happens, which applies to both variant 1) and variant 2):

[0192] From the process gas (or catalyst gas) H 2 a hydrogen molecule decomposes and the two hydrogen atoms attach themselves to two carbon atoms of the diamond disc or diamond seed, which in turn give up their bond to each other.

[0193] Then a hydrogen atom splits off from the methane gas and forms a H with the hydrogen atom, which had temporarily bonded to a carbon atom of the diamond lattice. 2 molecule and thus releases the carbon atom, which can now combine with the free valence of the carbon atom of the methane.

[0194] The same process also occurs with the second carbon atom, which has a free valence once one H atom has been removed.

[0195] Finally, the H 2 -Gas plasma gives each of the halfway bound methane gas molecules an H atom, whereupon the two free valences of the two carbon atoms of the diamond can bond with each other.

[0196] Thus, two new carbon atoms are docked to the diamond, and the diamond has grown a little bit.

[0197] Depending on the temperature and gas mixture, the growth rate is up to 8 µm / h, sometimes up to 10 µm / h.

[0198] Subsequent annealing of the diamond disc, as is common in the production of synthetic diamonds—that is, the "crystallization" of the diamond structure and color enhancement in the HPHT reactor—is not possible. The double-structured quartz-diamond glass might not survive this procedure unscathed. Therefore, the growth rate in this process is kept relatively low, resulting in a better color and purer structure of the diamond part and eliminating the need for subsequent crystallization in the annealing process using the HPHT process.

[0199] After growth, the finished diamond disc is mechanically polished, preferably on the accessible surfaces, in order to have an absolutely smooth surface

[0200] If, in the process for embodiment 1), we incorporate an additional film, for example a thin layer of silicon, e.g., approximately between 5 nm and 10 nm, between the carrier disk 6 and the metal film 1003, this additional film causes the polycrystalline "non-diamond carbon" (NDC) to be incorporated into the silicon (SiC), only to then dissolve again in the plasma process. Therefore, the additional film can improve the optical quality of the component. Furthermore, due to its minimal thickness, the additional film represents a film that has a certain elasticity and therefore reduces the mechanical stress due to the different expansion coefficients of quartz glass and diamond.

[0201] For the process for producing the diamond wafer without a carrier wafer (version 2), we prefer to use a standard semiconductor wafer made of pure silicon. Silicon already has a perfect crystallographic structure, similar to that of diamond—a face-centered cubic crystal structure. Furthermore, the semiconductor wafer made of pure silicon has an expansion coefficient of only 2.5 x 10 -6 K -1 . This is still two and a half times the expansion coefficient of synthetic diamond (1.0 x 10 -6 K -1 ). However, apart from special glasses such as pure quartz glass, this is a coefficient of expansion that is very close to that of diamond. For comparison: sapphire has 6.0 x 10 -6 K -1 , Float glass has 9.2 x 10 -6 K -1 .

[0202] We apply a metal film, such as nickel, to the wafer. The layer thickness should be approximately 5 nm or 10 nm. Not only does nickel have the same crystallographic structure as diamond (the face-centered cube), but the size of the nickel unit cell corresponds to the size of the diamond unit cell, with only a 1.5% deviation (nickel 3.52 Å, diamond 3.57 Å). We then coat the silicon / metal film substrate with DND diamond powder. We then grow synthetic diamond onto the substrate using a CVD process, preferably in the crystallographic orientation (110) or (100). The growth rate is approximately 8 µm / h. If we want to produce a diamond glass approximately 1 mm thick, we therefore need approximately 150 hours. We remove the substrate coated with the diamond film from the reactor after 6 days. We first use a laser to remove the polycrystalline carbon from the edges of the diamond glass.We then laser cut the glass to the exact desired size and shape. We then sand it on both sides until it reaches the exact thickness you require.

[0203] Afterwards, a coating or multiple coatings are preferably applied to the inside.

[0204] In addition to the above written description of the invention, reference is hereby explicitly made to the graphic representation of the invention in the figures for its supplementary disclosure. List of reference symbols 1 watch glass 2 Outside 3 Inside 4 Cover plate 5 Coating 5a Coating level 6 carrier disc 7 Intermediate layer 8 Anti-reflective coating 9 Recess 10 decorative element 11 Double layer 12 diamond layers 13 additional shift 30 Ground level 31 Seed (substrate) 32 diamond blanks 33 Growth direction 40 o'clock 41 housings 42 hands 43 Bracelet 44 Dial 410 interior 501 Coating thickness (coating thickness) 502 Thickness of the cover plate (cover plate thickness) 503 Thickness of the carrier disc (carrier disc thickness) 504 Thickness of the intermediate layer (interlayer thickness) 1001 CVD reactor 1002 silicon substrate (substrate) 1003 Metal film 1004 diamond crystals 1005 nickel-silicon interlayer 1006 carbon 1007 polycrystalline layer 1008 silicon-nickel particles

Claims

[1] Watch glass (1), in particular for a wristwatch, comprising: a cover plate (4) made of diamond, and • a layer formed as a carrier disc (6) with a lower refractive index than the cover disc (4) and a thickness (503) greater than the wavelengths of visible light, • and / or at least one layer formed as a coating with a lower refractive index than the cover plate (4) and a thickness (501) greater than the wavelengths of visible light. [2] Watch glass according to claim 1, comprising a double layer (11) on the outside of the cover plate (4), with a diamond layer (12) and an additional layer (13) between the cover plate (4) and the diamond layer (12), the additional layer (13) having a lower refractive index than the cover plate (4) and the diamond layer (12). [3] Watch glass (1), in particular for a wristwatch, comprising: a cover plate (4) made of diamond, and a double layer (11) on the outer side (2) of the cover plate (4), with a diamond layer (12) and at least one additional layer (13) between the cover plate (4) and the diamond layer (12), wherein the at least one additional layer (13) has a lower refractive index than the cover plate (4) and the diamond layer (12). [4] Watch glass (1) according to one of the preceding claims, wherein the cover plate (4): • has a thickness (502) of at least 0.1 mm, preferably at least 0.3 mm, more preferably at least 0.5 mm, preferably at least 0.75 mm, preferably at least 1 mm; • and / or is made of synthetic diamond; • and / or is made of polycrystalline synthetic diamond or monocrystalline synthetic diamond. [5] Watch glass (1) according to one of the preceding claims except claim 3, comprising the layer formed as a carrier disc (6) which is firmly connected to the cover disc (4); in particular wherein the carrier disc • has a thickness (503) of at least 0.3 mm, preferably at least 0.5 mm, more preferably at least 1 mm, preferably at least 1.5 mm; • and / or is thicker than the cover plate (4); • and / or is made of a different material than the cover plate (4); • and / or made of glass, in particular of a glass with an expansion coefficient between 0.001 x 10 -6 K -1 and 2 x 10 -6 K -1 , in particular made of quartz glass or of Sitall or Vycor or Zerodur or Cer Vit or of plastic or of sapphire glass. [6] Watch glass (1) according to claim 5, comprising a layer formed as an intermediate layer (7) between the cover plate (4) and the carrier plate (6), wherein the intermediate layer (7) firmly connects the cover plate (4) to the carrier plate (6); in particular wherein the intermediate layer (7): • is thinner than the cover plate (4); • and / or is thinner than the carrier disc (6); • and / or consists of at least one cured adhesive layer, preferably of a cured UV adhesive, or of at least one laminating layer made of / with EVA, PVB, Sentry Glass or another laminating film. • and / or has a refractive index which is up to + / - Δn=0.4, preferably up to + / - Δn=0.2, or equal to the refractive index of the carrier disc (6); • and / or has a refractive index between 1.4 and 1.6, in particular 1.48; • and / or has a thickness (504) of at least 0.05 mm, preferably at least 0.1 mm; • and / or has a thickness (504) of at most 0.8 mm, preferably at most 0.4 mm. [7] Watch glass (1) according to one of claims 1 or 2, designed as a single-pane watch glass, only with the cover plate (4) and the at least one layer designed as a coating (5) on the cover plate (4), and in particular also with the double layer (11). [8] Watch glass (1) according to one of the preceding claims, comprising the at least one layer formed as a coating (5), wherein the coating (5) is applied to the inner side (3) of the cover plate (4). [9] Watch glass (1) according to one of the preceding claims, comprising the at least one layer formed as a coating (5), wherein the coating (5), formed as a multiple coating, comprises a plurality of coating planes (5a) arranged one above the other and made of the same or different materials; preferably wherein the coating planes (5a) have a gradually lower refractive index from the outside to the inside. [10] Watch glass (1) according to one of the preceding claims including claim 5, comprising the at least one layer formed as a coating (5), wherein the coating (5) is applied to the inner side (3) of the carrier disc (6). [11] Watch glass (1) according to one of the preceding claims, wherein at least two of the, preferably all of the layers, preferably with the exception of the layer formed as an intermediate layer (7), have a gradually lower refractive index from the outside to the inside. [12] Watch glass (1) according to one of the preceding claims except claim 3, wherein by at least one, preferably at least two, more preferably at least three, of the layers the refractive index on the inside of the cover plate (4) is reduced to at least 1.8, preferably at least 1.

5. [13] Watch glass (1) according to one of the preceding claims except claim 3, comprising at least one layer formed as an anti-reflective coating (8), in particular applied to one or more planes in which the refractive index is reduced to at least 1.8, preferably at least 1.5, each anti-reflective coating (8) being matched to the media adjacent to it. [14] Watch glass (1) according to one of the preceding claims, wherein the cover plate (4) • a diamond with crystal structure type IIa, • and / or a monocrystalline, synthetic diamond, wherein a surface of the cover plate (4) runs either parallel to one of the crystallographic planes (100), (010) or (001), or parallel to one of the crystallographic planes (110), (101), (011)., • and / or is made of polycrystalline diamond, preferably with nano-crystalline diamond cells larger than 1nm, preferably larger than 50nm, or micro-crystalline diamond cells larger than 1µm, preferably larger than 50µm. [15] Watch glass (1) according to one of the preceding claims, wherein when using a polycrystalline synthetic diamond as cover plate (4), the nucleation side forms the inside (3) and the growth side forms the outside (2) of the cover plate (4). [16] Watch glass (1) according to one of the preceding claims, further comprising at least one decorative element (10), in particular a gemstone, which is arranged in a recess (9) formed in the carrier disc (6). [17] Watch glass (1) according to claim 16, wherein an upper region of the decorative element (10) is in direct contact with the connecting intermediate layer (7) and / or wherein a region of the recess (9) below a contact region of the decorative element (10) with a wall of the recess (9) has only air or vacuum. [18] Method for producing a watch glass (1), in particular a watch glass (1) according to one of the preceding claims except claim 3, comprising: • Providing a substrate (31) lying on a ground plane (30), • Growing a synthetic diamond blank (32) on the substrate (31) along a growth direction (33) perpendicular to the base plane (30), in particular by means of a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process, • Cutting and / or grinding the diamond blank (32) to produce the cover plate (4), and • Connecting the cover plate (4) to a layer formed as a carrier plate (6) with a lower refractive index than the cover plate (4) and a thickness (503) greater than the wavelengths of visible light, and / or connecting the cover plate (4) to at least one layer formed as a coating (5) with a lower refractive index than the cover plate (4) and a thickness (501) greater than the wavelengths of visible light. [19] A method according to claim 18, comprising the step: Connecting the outside of the cover plate (4) with a double layer (11), which has a diamond layer (12) and an additional layer (13) between the cover plate (4) and the diamond layer (12), wherein the additional layer (13) has a lower refractive index than the cover plate (4) and the diamond layer (12). [20] Method for producing a watch glass (1), in particular a watch glass (1) according to claim 3, in particular for a wristwatch, comprising: • Providing a substrate (31) lying on a ground plane (30), • Growing a synthetic diamond blank (32) on the substrate (31) along a growth direction (33) perpendicular to the base plane (30), in particular by means of a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process, • Cutting and / or grinding the diamond blank (32) to produce the cover plate (4), and, • Connecting the outer side of the cover plate (4) to a double layer (11) comprising a diamond layer (12) and an additional layer (13) between the cover plate (4) and the diamond layer (12), wherein the additional layer (13) has a lower refractive index than the cover plate (4) and the diamond layer (12). [21] Method according to one of the preceding method claims, comprising: • Separating the diamond blank (32) from the substrate by cutting and / or grinding when using a substrate designed for heteroepitaxy or a substrate designed for homoepitaxy, in which the substrate itself consists of diamond or of a polycrystalline, fragmented diamond layer. • and / or cutting the diamond blank (32) perpendicular to the growth direction (33), • and / or cutting the diamond blank perpendicular to the growth direction (33) into at least several usable cover disks (4) or into at least one usable cover disk (4) and at least one usable substrate (31), • and / or grinding the diamond blank (32) in a plane perpendicular to the growth direction (33). [22] Method according to one of the preceding method claims, wherein: • a substrate designed for heteroepitaxy is used, • or for homoepitaxy a substrate with a large number of diamond particles is used, • or a monocrystalline diamond is used as a substrate. [23] Method according to one of the preceding method claims, wherein the diamond blank (32) is subjected to a post-treatment with high pressure and / or high temperature after growth in order to achieve an improvement in the color and / or the final crystal structure [24] Method for producing a watch glass (1), in particular a watch glass (1) according to one of the preceding claims, provided that the cover plate (4) is arranged directly on the carrier plate (6), comprising the following steps: • Providing a carrier plate (6) made of glass, in particular quartz glass, which is transparent to visible light and has a metal film on the upper side, • Growing a, in particular monocrystalline or quasi-monocrystalline, diamond layer as a cover disk (4) on the upper side of the carrier disk (6) by means of hetero-epitaxy by chemical vapor deposition, in particular by means of a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process. [25] Method for producing a, in particular monocrystalline or quasi-monocrystalline, diamond disc as a cover disc (4) by means of hetero-epitaxy for a watch glass (1), in particular a watch glass (1) according to one of the preceding claims, comprising the following steps: • Providing a substrate (1002) made of preferably pure, crystalline silicon, • Applying a metal film (1003) on top of the silicon substrate (1002), • preferably conditioning the metal film (1003) by annealing, • Applying diamond powder (1004), in particular a layer of DND (detonation nano-diamonds), to the, in particular conditioned, metal film, • Growing a diamond disc by means of chemical vapor deposition, in particular by means of a microwave plasma chemical vapor deposition (MPCVD) process or a hot filament CVD (HFCVD) process, on said metal film, • Removing the silicon substrate (1002) with the metal film from the diamond disk. [26] Watch (40), in particular a wristwatch, comprising a housing (41) and a watch glass (1) arranged on the housing (41) according to one of the preceding claims to the watch glass (1) and / or manufactured according to one of the preceding method claims. [27] Watch (40), in particular a wristwatch, comprising a case (41) and a watch glass (1) arranged on the case, which consists of diamond, in particular exclusively of diamond without any additional layer.

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