COLOR-CHANGEABLE GEMSTONES

Abstract

The invention relates to a decorative ornamental element containing a transparent plano-convex gemstone, a wavelength-selective layer and a color-changeable seating surface, thus being able to cause aesthetic effects and signal effects by color changes. The ornamental element is characterized by a high brilliance and decorative color effect.

Claims

1. A decorative ornamental element, containing: a. a transparent gemstone with a plano-convex geometry, b. a wavelength-selective layer, and c. a color-changeable seating surface.

2. The decorative ornamental element according to claim 1, characterized in that said transparent gemstone is made of glass or plastic.

3. The decorative ornamental element according to claim 1 or 2, characterized in that said transparent gemstone is faceted.

4. The decorative ornamental element according to claim 3, characterized in that an inclination angle of a first facet to a base surface of the transparent gemstone is within an angular range of 10 to 40.

5. The decorative ornamental element according to claim 3 or characterized in that said wavelength-selective layer is applied: a) to said gemstone on a planar side opposed to a faceted side, or b) to said seating surface.

6. The decorative ornamental element according to claim 1, characterized in that said wavelength-selective layer is made of a wavelength-selective coating or a wavelength-selective film.

7. The decorative ornamental element according to claim 6, characterized in that said wavelength-selective layer contains at least one metal and/or metal compound.

8. The decorative ornamental element according to claim 1, characterized in that said wavelength-selective layer reflects and transmits in a wavelength range of from 380 to 780 nm.

9. The decorative ornamental element according to claim 8, characterized in that said wavelength-selective layer additionally transmits at least 20% in a wave-length range of from 360 to 420 nm.

10. The decorative ornamental element according to claim 8, characterized in that said wavelength-selective layer has an average reflectance of less than 75% in a wavelength range of from 400 to 700 nm.

11. The decorative ornamental element according to claim 1, characterized in that an electronically switchable display is used as said seating surface.

12. The decorative ornamental element according to claim 11, characterized in that said electronically switchable display switches between black and white colors.

13. The decorative ornamental element according to claim 1, characterized in that components a) to c) of said decorative ornamental element are bonded together by an adhesive.

14. A process for changing the color of a decorative ornamental element according to claim 1, characterized in that the color of the seating surface is changed by means of an electronic circuit.

15. The decorative ornamental element of claim 7, wherein the wavelength-selective layer has a structure comprising a sequence of SiO.sub.2 and TiO.sub.2 layers.

Description

LIST OF FIGURES

[0062] FIG. 1: Structure of the decorative ornamental element A: B=gemstone, C=wavelength-selective layer, D=color-changeable seating surface.

[0063] FIG. 2: Inclination angle of the first facet.

[0064] FIG. 3: Inclination angle of the first facet as well as peripheral region and inclination angle .

[0065] FIG. 4: Fundamental beam path for a black seating surface; A is the incident light, and B is the reflected light.

[0066] FIG. 5: Fundamental beam path for a white seating surface; A is the incident light, and B is the reflected light.

[0067] FIG. 6: Example of an average reflectance of less than 75%.

[0068] FIG. 7: Example of an average reflectance of more than 75%.

[0069] FIG. 8: Angular dependence of the reflected spectrum of Table 1, viewing direction from 0 to 85.

[0070] FIG. 9: Measuring set-up for determining the color location: (1) Ornamental element, (2) measuring camera, (3) hemisphere with reflecting inner surface, (4) light source, (5) opening with 215, (6) diameter of the hemisphere, (7) distance from center of hemisphere to camera.

[0071] FIG. 10: Measuring arrangement for determining the brilliance: (1) Ornamental element, (2) measuring camera, (3) diffuser, (4) light source, (5) semitransparent mirror, (6) distance from ornamental element to diffuser, (7) distance from ornamental element to measuring camera.

[0072] FIG. 11: Measurement of brilliance with coating variant 2 and a white seating surface.

[0073] FIG. 12: Measurement of brilliance with coating variant 2 and a black seating surface.

[0074] FIG. 13: Measurement of brilliance without a wavelength-selective layer and with a white seating surface.

[0075] FIG. 14: Measurement of brilliance without a wavelength-selective layer and with a black seating surface.

EXAMPLES ACCORDING TO THE INVENTION

[0076] Different decorative ornamental elements were examined in various measurements. Ornamental elements were constructed from a transparent gemstone, a wavelength-selective layer and a color-changeable seating surface. The wave-length-selective layer was designed as a wavelength-selective PVD coating (see above). Black or white sheets were used as the color-changeable seating surface for the measurements for reasons of practicability. In their optical properties, the sheets correspond to an e-paper and enabled a small and compact measuring set-up. As a white sheet, the product 303/W, and as a black sheet, the article 303/B of the company Coroplast were used.

[0077] In all measurements, the transparent circular faceted flatback gemstone Chess-board Circle (Art. No. 2035 with 14 mm diameter) of the company Swarovski was used as the transparent gemstone.

[0078] The gemstones were subjected to vapor deposition by a PVD process with the cubic coating plant (Balzers BAK760), see position C in FIG. 1. The layer materials were evaporated by means of an electron beam evaporator. The deposition on the gemstone surface was supported by accelerated oxygen ions from an ion source of the type Veeco Mark II.

[0079] The wavelength-selective PVD coating had a sufficient UV transparency that enabled the adhesive to be cured. A PVD-coated Chessboard Circle gemstone was applied with a commercially available transparent UV-curing adhesive to the white sheet, and a second, equally coated Chessboard Circle gemstone was applied to the black sheet, see position D of FIG. 1.

[0080] Coating variant 1 as shown in Table 1 (see below) was chosen as a wavelength-selective PVD coating, in order to have an example of colors with a high saturation.

[0081] In an approximately vertical view, the color magenta is obtained for a white seating surface, and the color green for a black seating surface.

[0082] As another example, coating variant 2 from Table 2 (see below) was chosen. In an approximately vertical view, yellow is obtained for a white seating surface, and blue for a black seating surface.

[0083] In the brilliance measurements, Chessboard Circle gemstones without a wave-length-selective layer were used as comparative examples, in order to demonstrate the importance of the layer to brilliance. The transparent Chessboard Circle gemstones with the UV-curing adhesive were applied directly to the white and black sheets.

TABLE-US-00001 TABLE 1 Coating variant 1 for the colors magenta and green; colors for an approximately vertical view. Layer # Material Layer thickness [nm] 1 TiO.sub.2 143 2 SiO.sub.2 100 3 TiO.sub.2 69 4 SiO.sub.2 30 5 TiO.sub.2 59 6 SiO.sub.2 117 7 TiO.sub.2 28 8 SiO.sub.2 129 9 TiO.sub.2 26 10 SiO.sub.2 129 11 TiO.sub.2 21 12 SiO.sub.2 136 13 TiO.sub.2 27 14 SiO.sub.2 127 15 TiO.sub.2 133 16 SiO.sub.2 65

TABLE-US-00002 TABLE 2 Coating variant 2 for the colors yellow and blue; colors for an approximately vertical view. Layer # Material Layer thickness [nm] 1 TiO.sub.2 43.8 2 SiO.sub.2 38.1 3 TiO.sub.2 65.2 4 SiO.sub.2 52 5 TiO.sub.2 50 6 SiO.sub.2 83.8 7 TiO.sub.2 41.6 8 SiO.sub.2 89.2 9 TiO.sub.2 39.8 10 SiO.sub.2 89.6 11 TiO.sub.2 55.1 12 SiO.sub.2 39.1 13 TiO.sub.2 67 14 SiO.sub.2 138.5

Measuring Set-ups

[0084] Measurement of the color location

[0085] The L*a*b* color space according to DIN EN ISO 11664-4 was used to measure the color location, and the color distance E was calculated to calculate the color change (see above).

[0086] The measuring set-up is shown in FIG. 9. A hemispherical, approximately diffuse illumination was chosen as the light source, and a digital measuring camera was used to detect the color location. A diffuse illumination has the advantage that there is no preferential direction. The decorative ornamental element was illuminated indirectly because an annular light source (4) in FIG. 9 had a light outlet only in the direction of the hemisphere (3). The illumination of the decorative ornamental element was effected by the reflections at the hemisphere. However, the illumination was only approximately diffuse, because an opening (5) in the hemisphere (3) was necessary for measuring with the camera. The hemisphere (3) in FIG. 9 was made of plastic, had a diameter (6) of 300 mm and was provided with a white color at its inner surface (matte acrylic paint of the type RAL9010M). An annular light source of the type Osram L32W/25C Universal White was used as the light source (4). This set-up achieved approximately diffuse light conditions.

[0087] The hemisphere (3) had an aperture range (5) of 215 for the detection of the color location. A camera of the type Canon EOS400D was used as the measuring camera (2) at a distance (7) of 200 mm from the center of the hemisphere to the front lens of the camera. The decorative ornamental element (1) was placed with a horizontal offset of about 12 mm from the center of the hemisphere. This simulates an inclined viewing angle onto the decorative ornamental element, as is often the case when ornamental elements are viewed visually. The direction of the horizontal offset is arbitrary, because the illumination is sufficiently diffuse.

[0088] Measurement of Brilliance

[0089] The decorative ornamental element is brilliant also upon a color change (see above). In order to show how important the structure of the decorative ornamental element is to brilliance, brilliance measurements were performed with and without a wavelength-selective coating. The measurements were effected in a darkened room in order to avoid further disturbing light influences.

[0090] The measuring set-up is shown in FIG. 10. The decorative ornamental element (1) was illuminated with an approximately collimated light source (4) with a beam expansion of 20.25 via the semitransparent mirror (5), the Plate Beamsplitter #46-583 of the company Edmund Optics. The approximately collimated light source was realized with a commercially available focusable white LED light projector.

[0091] The light reflected by the ornamental element was collected at a distance of 300 mm (6) on the diffuser (3). The diffuser (3) had a size of 600600 mm.sup.2 and was a commercially available diffuser sheet, the Luminit Light Shaping Diffuser 60. At a distance (7) of 1500 mm from the ornamental element to the measuring camera, a measuring camera of the type AVT Manta G-235C with a 12 mm objective was mounted in order to measure the distribution of the reflected light.

[0092] The Following Measurements were Performed:

[0093] V1: Example according to the invention: Measurement of the color location for white and black seating surfaces with coating variant 1

[0094] V2: Example according to the invention: Measurement of the color location for white and black seating surfaces with coating variant 2

[0095] V3: Example according to the invention: Measurement of brilliance by measuring the distribution of the reflected light of the decorative ornamental element for white and black seating surfaces with coating variant 2

[0096] V4: Comparative Example: Measurement of brilliance by measuring the distribution of the reflected light of the decorative ornamental element for white and black seating surfaces without a wavelength-selective layer

[0097] Results of the Measurements:

[0098] V1:

[0099] The measurement V1 of the color location with coating variant 1 gemstones for white and black seating surfaces had the results:

[0100] black seating surface: L*=71.4/a*=73.4/b*=14.5

[0101] white seating surface: L*=39.4/a*=63.5/b*=67.6

[0102] The color distance between the black and white seating surfaces was AE=160.6.

[0103] V2:

[0104] The measurement V2 of the color location with coating variant 2 gemstones for white and black seating surfaces had the results:

[0105] black seating surface: L*=71.2/a*=18.8/b*=68.3

[0106] white seating surface: L*=58.9/a*=57.9/b*=67.2

[0107] The color distance between the black and white seating surfaces was E=156.2.

[0108] V3:

[0109] The measurement of the brilliance with gemstones of coating variant 2 for a white seating surface yielded the distribution of FIG. 11. The distribution has many pronounced points of reflected light.

[0110] For a black seating surface, the distribution of FIG. 12 was obtained. This distribution also has many pronounced points of reflected light.

[0111] V4:

[0112] The measurement of the brilliance was performed for white and black seating surfaces even without a wavelength-selective layer. Without a wavelength-selective layer, the reflection was significantly reduced for a white seating surface, as can be seen from FIG. 13.

[0113] The same applies for a black seating surface. In FIG. 14, the reduced reflection of the light is clearly seen.

[0114] Discussion of the Measuring Results:

[0115] From the measurements V1 and V2, it can be seen that the color change of the seating surface from black to white leads to significant color changes of the decorative ornamental element. The color of the decorative ornamental element can be influenced by the type of gemstone, the structure of the wavelength-selective layer and the color of the seating surface.

[0116] The measurements V3 and V4 clearly show that the wavelength-selective layer is essential to the optical appearance, especially to brilliance. For both white and black seating surfaces, broadly distributed and pronounced points of reflected light, which correspond to a high brilliance (see above), are obtained with the wave-length-selective coating, see FIGS. 11 and 12. Without a wavelength-selective coating (FIGS. 13 and 14), only a few weakly pronounced points of reflected light are present, which correspond to a low brilliance.