CH717402A1 - Variable shade watch component. - Google Patents

Abstract

The present invention relates to a watch component (201) comprising, at least on a part of its surface, photochromic pigments having a first shade (201.a) when exposed to UV radiation and a second shade (201.b). different from the first shade, when they are not subjected to UV radiation.

Description

Technical area

The present invention relates to the field of watch components.

State of the art

[0002] In general, a watch component has only one shade. This is inherent in the material of which said part is made. There are many surface treatments making it possible to locally modify the color of the material such as for example the anodization treatments often used for the decoration of titanium parts as described in patent JPS59143986. The original shade is changed to a second shade, but it is not possible to revert to the original shade.

[0003] It would be interesting to be able to provide a component having a variable shade in order to improve the readability of a display or to present an original aesthetic.

One possibility for obtaining a variable hue is the use of so-called holographic processes; a network makes it possible to separate the light in different wavelengths which does not give a single shade but all the visible colors. However, it is not easy to integrate such a hologram in a timepiece, in particular a covering.

[0005] There are also pigments the hue of which varies during a modification of the environment. For example, as described in patent EP3173455, so-called thermochromic pigments are known, the color of which varies as a function of temperature. When the watch is worn, its temperature varies little and remains close to that of the human body, especially in the case of metallic watches, so that the variations in color that could be obtained would be limited or at best seasonal.

[0006] There are also pigments the hue of which varies as a function of an electric field, these pigments are said to be electrochromic and are mainly used in the application of building glazing. These pigments are activated by being physically connected to a source of electrical energy, which is limiting for a horological application, in particular in the case of a mechanical watch.

[0007] Other applications in the field of security exist, in particular for the manufacture of labels, and use contactless technology, such as an RFID or NFC reader. In this case, the shade variation requires an external device to be obtained.

In the electronic field, we also know the displays whose contrast or brightness adapts according to external conditions to improve reading comfort.

[0009] The materials currently available have a single shade, which may have good ergonomics for reading, or for visibility, in a first light condition but be unsuitable in another, such as for example in artificial ambient light and in direct sunlight.

Disclosure of the invention

[0010] The aim of the invention is to provide a component made of a material whose hue is capable of varying reversibly depending on the ambient light, making it possible to improve its visibility and to present an original aesthetic.

This object is achieved using a watch component comprising, at least on a part of its surface, photochromic pigments having a first shade when they are exposed to radiation containing UV and a second shade, different of the first shade, when they are not subjected to radiation containing UV.

This variation in color in response to a change in UV exposure, such as for example the passage from a room with artificial light to a place with natural light, is carried out in a limited time, preferably in less than 180 seconds, preferably between 10 and 60 seconds.

According to a variant of the invention, the photochromic pigments are of naphthopyran or spiro-naphthoxazine nature.

According to another variant of the invention, the proportion by mass of the pigment in said watch component is between 0.01% and 5%, preferably between 0.02 and 1%.

According to another variant of the invention, the first shade is blue, green, orange, or yellow.

According to another variant of the invention, the second shade of the pigment is colorless, so that the presence of the pigment is not perceptible in this state.

[0017] According to another variant of the invention, the watch component comprises at least on part of its surface fluorescent pigments, these pigments being visible only with the aid of black light.

[0018] According to another variant of the invention, the watch component comprises at least on part of its surface phosphorescent pigments, which become charged by UV radiation and which are visible in very low light.

The component of the invention is a watch component preferably chosen from the list: dial, middle part, hand, bezel, bridges or plate.

Description of figures

Other features and advantages will emerge clearly from the description below, by way of indication and in no way limiting, with reference to the appended figures, in which: FIG. 1 represents a chronograph watch provided with a dial according to the invention, subjected to artificial light without UV. FIG. 2 represents the watch of FIG. 1, said dial having been subjected for at least 10 seconds to natural light containing UV. Fig. 3 shows a watch provided with a single hand produced according to one embodiment of the invention, said hand being subjected to artificial light without UV. FIG. 4 shows the watch of FIG. 3 subjected for at least 20 seconds to natural light, such as the sun, containing UV. FIG. 5 represents an illustration of a watch produced in a carbon material according to one embodiment of the invention. FIG. 6 represents the watch of FIG. 5, said watch having been subjected for at least 30 seconds to natural light, such as the sun, containing UV. FIG. 7 represents a cycle of evolution of the hue as a function of the lighting conditions.

Embodiment of the invention

The invention provides a watch component having a variable hue depending on the light environment. Various variants of the invention are described by way of non-limiting examples.

In a first embodiment illustrated in Figures 1 and 2, the invention relates to a chronograph watch with improved readability, comprising a dial 101 and chronograph counters 102.

In order to improve the readability of the counters as a function of the brightness, it may be advantageous to vary the contrast between the color of the dial and that of the counters. For this, the dial 101, with the exception of the chrono counters 102, is coated with a mixture of varnish and photochromic pigments. The varnish is zappon and the proportion of varnish is between 98.0% and 99.99% by weight of the pigment / varnish mixture. The coated part of the dial 101 takes on a first color 101.a when the watch is subjected to UV rays, for example when it is worn outside as shown in FIG. 1. When worn indoors under artificial lighting, as shown in FIG. 2, the dial is not subjected to UV rays and takes on a second shade 101.b, different from the first, which makes it possible to modify the contrast between the dial 101 and the counters 102 in order to optimize the readability of the 'display in different light conditions.

In a second embodiment illustrated in Figures 3 and 4, the invention is applied to a hand 201 of the time display on a watch. The body of the needle is for example made of sapphire covered with a mixture of varnish and photochromic pigments, comprising 0.05% by weight of pigment relative to the varnish. When worn inside as shown in FIG. 3, the pigments take on a second colorless shade 201.b and the hand is translucent, the watch is worn more like a jewel and the time reading is discreet. When worn outside, shown in FIG. 4, the pigments have a first opaque shade 201.a which allows better visibility of the hand and therefore better readability of the time.

In a third embodiment, the invention relates to a watch case 301, made of carbon fibers of different lengths mixed randomly and of a polyurethane resin containing a portion of photochromic pigment. This material is called "forged carbon" by those skilled in the art.

The resin / pigment mixture has a proportion of 1% by weight of pigment. The set of fibers and the resin / pigment mixture is then inserted into a mold and then undergoes a pressure-temperature cycle to form the box 301. Note that the temperature does not exceed 200 ° C.

The resin / pigment mixture has a translucent and colorless tint when not exposed to UV radiation so that the box thus produced has a forged carbon appearance, with a second shade 301.b as illustrated in FIG. 5.

The box 301 has a first shade 301.a on at least part of the surface when it is exposed to UV rays as illustrated in FIG. 6.

In a variant of the third embodiment, phosphorescent pigments are added to the resin / photochromic pigment mixture. Thus, the middle part produced according to this variant has a third shade in a dark environment as illustrated in FIG. 7.

To produce a watch component according to the invention, one can for example use pigments of naphthopyran or spiro-naphthoxazine nature. Preferably, the proportion by weight of the pigment in the component is between 0.01% and 5%.

The shade variation in response to a change in UV exposure is preferably carried out in less than 180 seconds, preferably between 10 and 60 seconds.

The watch component according to the invention can see its color change between different shades among blue, green, orange, yellow or even colorless. In the latter case, the component appears in its original color.

It is also possible to provide that the component comprises, at least over part of its surface, fluorescent pigments and / or phosphorescent pigments.

The invention makes it possible to produce all kinds of watch components and in particular dials, middle parts, hands, bezels, bridges or plates.

Claims (10)

1. Watch component (101, 201, 301) comprising, at least on part of its surface, photochromic pigments exhibiting a first shade (101.a, 201.a, 301.a) when they are exposed to radiation containing UV rays and a second shade (101.b, 201.b, 301.b), different from the first shade, when they are not subjected to radiation containing UV. 2. Timepiece component according to one of the preceding claims, in which the variation in color in response to a change in UV exposure takes place between 10 and 180 seconds. 3. Timepiece component according to one of the preceding claims, in which the pigment is of naphthopyran nature. 4. Timepiece component, according to one of claims 1 to 2, wherein the pigment is of spiro-naphthoxazine nature. 5. Timepiece component, according to one of the preceding claims, in which the proportion by mass of the pigment in said component is between 0.01% and 5%. 6. Timepiece component according to one of the preceding claims, in which the first shade is blue, green, orange or yellow. 7. Timepiece component according to one of the preceding claims, in which the second shade is colorless. 8. Timepiece component, according to one of the preceding claims, which comprises at least on part of its surface fluorescent pigments. 9. Timepiece component, according to one of the preceding claims, which comprises at least on part of its surface phosphorescent pigments. 10. Component according to one of the preceding claims, characterized in that the component is chosen from the list: dial, middle part, hand, bezel, bridge or plate.