Luminescent timepiece display using optical coupling via microstructures
By using microstructures for optical coupling in watch pointers, and directly illuminating the pointer with a fixed illumination source, the problem of poor display of fluorescent or phosphorescent coatings at night is solved, and the luminous display effect that simplifies manufacturing and reduces cost is achieved.
Patent Information
- Application Number
- CN202410752465.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-12
- Filing Date
- 2024-06-12
- Publication Date
- 2024-12-13
AI Technical Summary
In existing watch pointer lighting systems, the use of fluorescent or phosphorescent coatings limits the selection and manufacturing complexity of light, especially in nighttime or in under-light environments, which are difficult to provide an effective luminous display.
The optical coupling is adopted for microstructure, and the light emitting indicator formed by the opaque metal layer and the transparent light guide layer is directly illuminated by fixed illumination sources such as LEDs or VCSELs, avoiding the absorption and re-emission of fluorescent materials, simplifying the manufacturing process and Reduced costs.
Achieving effective luminous display in night or in under-light environments simplifies pointer manufacturing process, reduces costs, and avoids color mixing problems in the light path, providing flexible color control and longer luminous duration.
Smart Images
Figure CN119126527A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a watch display device, which includes at least one light source and a group of pointers coaxial about a rotation axis between a dial carrying at least one reference scale on the top side and a crystal on the side facing the user, and the group of pointers includes at least a first luminous indicator, which includes a first light guide, which is arranged to diffuse a portion of the light emitted by the at least one light source.
[0002] The present invention relates to the field of displays for timepieces, in particular watches, and more particularly to illuminated displays. Background Art
[0003] EP19220169 describes the principle of pointer illumination using several light sources. A first source, usually an LED or a group of LEDs, remotely excites a secondary source, in particular a point placed under the pointer containing a fluorescent pigment. Therefore, the emission spectrum of the primary source and the excitation spectrum of the secondary source must match for the system to be effective. This limits the choice to LEDs that emit light sufficiently around 400nm. The maximum absorption peak of the fluorescent pigment is in the ultraviolet wavelength. The same document further describes the presence of a small hole in the head of the hour hand to allow light to pass through and thus reach the minute hand, which obviously complicates the manufacture of such a pointer. Summary of the invention
[0004] The object of the present invention is to develop a luminous indicator for a timepiece for display at night or in low-light environments, as an alternative to the fluorescent or phosphorescent coatings of the prior art.
[0005] To this end, the invention relates to a display device according to claim 1 . BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The objects, advantages and features of the present invention will become better understood upon reading the following detailed description given with reference to the accompanying drawings, in which: - Figure 1 is a schematic cross-sectional view of a first alternative embodiment of a pointer according to the invention, the schematic cross-sectional view being taken along the axis of rotation of the pointer; - Figure 2 is a schematic cross-sectional view of a second alternative embodiment of a pointer according to the present invention, the schematic cross-sectional view being taken along the axis of rotation of the pointer; - Figure 3 is a schematic cross-sectional view of a set of coaxial pointers according to the invention, the schematic cross-sectional view showing two superimposed pointers and being taken along a common axis of rotation of said pointers; - Figure 4 is a schematic cross-sectional view of a watch comprising a set of coaxial hands according to the invention, showing two superimposed hands illuminated by a lower light source and taken along their common axis of rotation. DETAILED DESCRIPTION
[0007] The invention relates to a luminous horological display using optical coupling via microstructures.
[0008] EP3845974A1 (incorporated herein by reference) describes a movable indicator for an analog display device, in particular a watch display device comprising one or more movable indicators (such as hands). The indicator comprises a multilayer component comprising an opaque metal layer and a transparent light-conducting layer, and forming a body and a head of the indicator. The head is centered relative to the axis of rotation of the indicator and is arranged to receive a luminous flux on its lower face facing away from the user. A fluorescent material is arranged on the transparent light-conducting layer at the head of the indicator to absorb at least a portion of the luminous flux and re-emit a second fluorescent light flux into the transparent light-conducting layer.
[0009] More specifically, the display device according to this document EP3845974A1 comprises a dial and such an indicator, which is arranged above the dial, i.e. on the watch glass side and is visible to the user, the respective hands of the indicators being superimposed and fastened to the respective arbors so as to rotate about a common axis of rotation, and the device comprising a fixed illumination source arranged to illuminate from below, i.e. on the bottom side of the dial facing away from the user and, except in the case of skeleton watches or mysterious watches, invisible to the user, all heads of the indicators being substantially parallel to the common axis of rotation by means of a luminous flux and having a wavelength shorter than that re-emitted by the fluorescent material. The fixed illumination source may comprise light emitting diodes (hereinafter referred to as LEDs) and / or organic LEDs, which are distributed around the arbors and mounted on a printed circuit element (hereinafter referred to as PCB), arranged below the dial, or may comprise a micro laser source of the VCSEL type arranged similarly.
[0010] On a similar basis or alternatively, the invention proposes to produce a watch display comprising at least one luminous hand, in particular by optical coupling via a microstructure. Due to the presence of the microstructure, such a luminous hand can be simpler than the one described in detail in EP 3845974 A1 which necessarily comprises a fluorescent material, making it possible to reduce the cost of the hand.
[0011] A particular object of the invention is to illuminate the hands of a watch on demand without using electrical wiping contacts.
[0012] The first proposal concerns the hour hand. On some hands, the pointer head is not very developed relative to the pointer body, or even barely exists, i.e. there is no widening around the hole relative to the pointer body and therefore no obstruction to the flow of light to the minute hand. This design avoids the need to create an aperture and the need to make a complex design; the only thing to avoid is direct light leakage when viewed from the side or at a grazing angle.
[0013] A second proposal involves coupling light into a light guide included in the hands. In the same way that light can leave the light guide with the aid of a structure that changes its path (e.g. a prism or a cone), the same type of structure can be used to bring light from an LED into the light guide, the LED being particularly positioned on a PCB that is located below the dial or on the dial, or that forms the dial.
[0014] This further lends itself to simple surface etching, which modifies the surface roughness. It is therefore possible to etch the coupling structures directly into the master used to replicate these structures on the light guide of the pointer at the same time as the extraction structures, rather than depositing fluorescent ink and complicating the process.
[0015] In the usual case where a set of pointers comprises a plurality of pointers, several options may be selected.
[0016] The first option is to standardize the brightness of at least two adjacent hands, and for this, different coupling zone designs (surface, shape, depth) must be considered. Providing a sufficiently large coupling surface for the minute hand ensures continuous luminous coupling on this hand despite the presence of the hour hand in the light path.
[0017] The use of fluorescent pigments in certain luminous hands is often hampered by the color differences that arise between two adjacent hands. Although a large proportion of the light coupled into the light guide comes from the fluorescent dots, some of this light can be coupled in without any special equipment, for example via the edge of the light guide. This involves color mixing between the light emitted by the fluorescent pigment and the original light emitted from the LED. For example, UV LEDs also emit blue light. This color mixing - which is difficult to control and has differences between the hour and minute hands - does not exist if the coupling occurs via microstructures, because there is no change in color via these microstructures.
[0018] Another alternative embodiment is to use this effect to make the pointer a different color. This can be done by accentuating the color mixing between fluorescents and the LED primary colors, although this is difficult to control. More simply, fluorescent dots that emit different colors can be used.
[0019] Another alternative embodiment involves replacing the fluorescent material with a phosphorescent material. After a short period of excitation, the user will only see the phosphorescence, and therefore the same color on both hands. This approach can also be advantageous in maximizing the duration of the luminous effect with a minimum energy balance. The ambient light seen by the watch and hands can also be used in part to recharge the phosphorescent material and produce light in the evening.
[0020] Thus, in order to provide a luminous display without necessarily having to rely on the use of luminescent or phosphorescent materials - which, apart from the present invention, can still be used for a colored alternative embodiment - the present invention more particularly relates to a display device 100 for a watch 1000, comprising at least one light source 200 and a set of hands 10 between a dial 300 carrying at least one reference scale on a top side 301 and a crystal 400 on the side facing the user. The set of hands 10 is movable about an axis of rotation D and, when it comprises several indicators, is coaxial about this axis of rotation D. The set of hands 10 comprises at least a first luminescent indicator 1 comprising a first light guide 11 arranged to diffuse some of the light emitted by the at least one light source 200.
[0021] According to the invention, the first light guide 11 comprises a first coupling microstructure 110 which is arranged to allow light to enter the first light guide 11 and / or to allow light to leave the first light guide 11 .
[0022] More specifically, at least one first luminous indicator 1 comprises several layers including an opaque metal layer 36 and a transparent layer 38 forming a first light guide 11, and forming a first head 15 and a first body 16, the first head 15 being centered relative to said rotation axis D and arranged to receive the light flux 54 on a first lower surface 152 not visible to a user. Such a first coupling microstructure 110 is arranged on or in the transparent light guide layer at the head 15 to provide input coupling into the transparent light guide layer.
[0023] In an alternative embodiment, the fluorescent material is arranged on or in a transparent light-guiding layer at the head 15 .
[0024] In another alternative embodiment, the phosphorescent material is arranged on or in a transparent light-guiding layer at the head 15 .
[0025] More specifically, the set of coaxial pointers 10 comprises at least a second luminous indicator 2 between the first luminous indicator 1 and the watch crystal 400, the second luminous indicator 2 comprising a second light guide 21 arranged to diffuse some of the light emitted by the at least one light source 200 and / or the first luminous indicator 1. The second light guide 21 comprises a second coupling microstructure 210 arranged to allow light to enter the second light guide 21 and / or to allow light to leave the second light guide 21.
[0026] More specifically, the group of coaxial pointers 10 includes a plurality of superimposed and coaxial luminous indicators between the first luminous indicator 1 and the watch crystal 400, each luminous indicator including a light guide arranged to diffuse a portion of light emitted by at least one light source 200 and / or a luminous indicator placed thereunder on a side facing away from the watch crystal 400, and each luminous indicator including a coupling microstructure arranged to allow light to enter the light guide and / or allow light to leave the light guide.
[0027] More specifically, at least one luminous indicator included in the set of coaxial pointers 10 comprises several layers including an opaque metal layer and a transparent layer forming a light guide, and forming a head and a body, the head being centered relative to the rotation axis D and arranged to receive the light flux 54 on a first lower face not visible to the user. Such a coupling microstructure is arranged on or in the transparent light guide layer at the head to absorb at least a portion of the light flux and re-emit a second fluorescent light flux into the transparent light guide layer.
[0028] More particularly, the fluorescent material is arranged on or in the transparent light guide layer of at least one luminous indicator included in the set of coaxial pointers 10 at the head to absorb at least a portion of the light flux and re-emit a second fluorescent light flux into the transparent light guide layer.
[0029] More particularly, the phosphorescent material is arranged on or in the transparent light-guiding layer of at least one luminous indicator included in the set of coaxial pointers 10 at the head to absorb at least a portion of the light flux and re-emit a second phosphorescent light flux into the transparent light-guiding layer.
[0030] In an alternative embodiment, inserting a fluorescent or phosphorescent material between the light source 200 and the light emitting indicator allows for easy colouring, but defeats the purpose of the light coupling solution provided by the fluorescent material to the light guide.
[0031] More specifically, the indicator closest to crystal 400 has a coupling surface combining its coupling microstructures which is larger than the coupling surface of the indicator immediately below, on the side facing away from crystal 400 .
[0032] More particularly, at least one luminous indicator included in the set of coaxial pointers 10 comprises a transparent light-guiding layer arranged to generate total internal reflection of the rays of the second light flux substantially perpendicular to said axis D of rotation.
[0033] More particularly, at least one luminous indicator included in the set of coaxial pointers 10 comprises several layers including an opaque metal layer and a transparent layer forming a light guide, and the luminous indicator comprises an optical insulating layer between the opaque metal layer and the transparent light guide layer. More particularly, but not limitingly, an adhesive, in particular a resin, is used to assemble the metal part of the pointer with the light guide part, and this adhesive or resin acts as an insulating layer, which has an optical index lower than the optical index of the light guide. The difference Δn between the refractive index of the optical insulating layer and the refractive index of the transparent light guide layer is in the range of 0.1 to 0.5, inclusive. Preferably, but not exclusively, a resin with an index greater than or equal to 1.1 is used for this purpose.
[0034] More particularly, the thickness of the optical insulating layer is in the range 5 to 15 μm. This corresponds to the use of liquid resins. For other horological applications (such as pendulums or clocks), where there are fewer restrictions on thickness, it is possible to use thin film resins, whose maximum thickness is then limited to 100 μm.
[0035] More particularly, at least one luminous indicator included in the set of coaxial pointers 10 has a flat upper face and a flat lower face perpendicular to the axis D of rotation.
[0036] More particularly, at least one luminous indicator included in the set of coaxial pointers 10 has a head comprising a central eyelet in which a socket made of an opaque material is arranged.
[0037] More specifically, the set of coaxial pointers 10 includes a plurality of superimposed and coaxial luminous indicators between the first luminous indicator 1 and the watch mirror 4, each luminous indicator including a head surrounding a rotation axis D and a body extending substantially perpendicularly to the rotation axis D, and a lower indicator, which is located closer to the dial 300 than an upper indicator located immediately above the lower indicator, having at least one auxiliary hole arranged around a central hole in its head on the watch mirror 400 side so as to allow the light flux to pass through the lower indicator via the at least one auxiliary hole so that at least a portion of the light flux is absorbed by the light guide of the upper indicator.
[0038] More particularly, at least one light source 200 is positioned below the dial 300 near the bottom side 302 of the dial 300 facing away from the crystal 400 relative to the dial 300, or is embedded in the dial 300, or is positioned on a PCB 201 positioned below the dial 300 near the bottom side 302 of the dial 300.
[0039] Even more particularly, at least one light source 200 is a stationary light source comprising micro laser sources of the Light Emitting Diode and / or Organic Light Emitting Diode and / or VCSEL type distributed around the axis D of rotation.
[0040] More particularly, at least one luminous indicator included in the set of coaxial pointers 10 includes at least one luminous indicator whose light guide includes a fluorescent material. The light source 200 is a fixed illumination source arranged to illuminate from below all the heads of the indicators included in the set of coaxial pointers 10 by means of a luminous flux substantially parallel to the axis of rotation D and having a wavelength shorter than the wavelength re-emitted by the fluorescent material.
[0041] More particularly, at least one luminous indicator included in the set of coaxial pointers 10 comprises at least two luminous indicators whose light guides comprise fluorescent materials emitting in different colors.
[0042] The invention further relates to a watch 1000 comprising at least one such display device 100 .
[0043] More specifically, at least one indicator included in the set of coaxial pointers 10 is a luminous pointer.
[0044] More specifically, at least one indicator included in the set of coaxial pointers 10 is a disc.
[0045] In short, the invention allows light to be coupled directly via the microstructure. It is no longer necessary to couple the light via absorption / re-emission by fluorescent materials. However, the use of the microstructure according to the invention in combination with fluorescent or phosphorescent elements makes it possible to obtain certain specific color effects.
Claims
1. A display device (100) for a watch (1000), comprising at least one light source (200) and comprising a set of pointers (10) coaxial about a rotation axis (D) between a dial (300) carrying at least one reference scale on a top side (301) and a mirror (400) on a side facing a user, the set of pointers (10) comprising at least a first luminous indicator (1), the first luminous indicator (1) comprising a first light guide (11), the first light guide (11) being arranged to diffuse a portion of the light emitted by the at least one light source (200), characterized in that The first light guide (11) comprises a first coupling microstructure (110) arranged in a transparent layer of the first light guide, the first coupling microstructure (110) being arranged to allow light to enter the first light guide (11) and / or to allow light to leave the first light guide (11).
2. The display device (100) according to claim 1, characterized in that The at least one first luminous indicator (1) comprises several layers, the several layers comprising an opaque metal layer (36) and a transparent layer forming the first light guide (11), and forming a first head (15) and a first body (16), the first head (15) being centered relative to the rotation axis (D) and arranged to receive a light flux on a first lower face (152) invisible to a user, and characterized in that the first coupling microstructure (110) is arranged on or in the transparent light guide layer at the head (15) to provide input coupling into the transparent light guide layer.
3. The display device (100) according to claim 1 or 2, characterized in that: The set of coaxial pointers (10) comprises at least one second luminous indicator (2) between the first luminous indicator (1) and the watch mirror (400), the second luminous indicator (2) comprising a second light guide (21), the second light guide (21) being arranged to diffuse a portion of the light emitted by the at least one light source (200) and / or the first luminous indicator (1), and is characterized in that the second light guide (21) comprises a second coupling microstructure (210) arranged in the transparent layer of the first light guide, the second coupling microstructure (210) being arranged to allow light to enter the second light guide (21) and / or to allow light to leave the second light guide (21).
4. The display device (100) according to one of claims 1 to 3, characterized in that The set of coaxial pointers (10) comprises a plurality of superimposed and coaxial luminous indicators between the first luminous indicator (1) and the watch mirror (400), each luminous indicator comprising a light guide arranged to diffuse a portion of light emitted by the at least one light source (200) and / or a luminous indicator placed thereunder on a side facing away from the watch mirror (400), and each luminous indicator comprising a coupling microstructure arranged to allow light to enter the light guide and / or allow light to leave the light guide.
5. The display device (100) according to one of claims 1 to 4, characterized in that At least one luminous indicator included in the set of coaxial pointers (10) includes several layers, including an opaque metal layer (36) and a transparent light-conducting layer, and forming a head and a body, the head being centered relative to the rotation axis (D) and arranged to receive a light flux on a first lower surface invisible to a user, and characterized in that the coupling microstructure is arranged on or in the transparent light-conducting layer at the head so as to absorb at least some of the light flux and re-emit a second light flux into the transparent light-conducting layer.
6. The display device (100) according to claim 5, characterized in that: A fluorescent or phosphorescent material is arranged on or in the transparent light-conducting layer (38) of at least one luminous indicator included in the set of coaxial pointers (10) at the head so as to absorb at least a portion of the light flux and re-emit a second light flux, respectively a fluorescent or phosphorescent light flux, in the transparent light-conducting layer.
7. The display device (100) according to one of claims 1 to 6, characterized in that The indicator closest to the crystal (400) has a coupling surface that combines its coupling microstructures, which is larger than the coupling surface of the indicator immediately below on the side facing away from the crystal (400).
8. The display device (100) according to claim 5 or 6, characterized in that: At least one luminous indicator included in the set of coaxial pointers (10) comprises a transparent light-guiding layer (38) arranged to generate total internal reflection of light rays of a second light flux substantially perpendicular to the rotation axis (D).
9. The display device (100) according to any one of claims 1 to 8, characterized in that: At least one luminous indicator included in the set of coaxial pointers (10) comprises several layers, the several layers comprising an opaque metal layer (36) and a transparent light-conducting layer (38), and the at least one luminous indicator comprises an optical insulation layer (40) between the opaque metal layer (36) and the transparent light-conducting layer (38), and is characterized in that a difference Δn between a refractive index of the optical insulation layer and a refractive index of the transparent light-conducting layer (38) is in the range of 0.1 to 0.5, inclusive.
10. The display device (100) according to claim 9, characterized in that: The thickness of the optical insulation layer (40) is in the range of 5 μm to 15 μm.
11. The display device (100) according to one of claims 1 to 10, characterized in that At least one luminous indicator included in the set of coaxial pointers (10) comprises a flat upper face and a flat lower face perpendicular to the rotation axis (D).
12. The display device (100) according to one of claims 1 to 11, characterized in that At least one luminous indicator included in the set of coaxial pointers (10) comprises a head including a central hole in which a socket made of an opaque material is arranged.
13. The display device (100) according to one of claims 1 to 12, characterized in that The set of coaxial pointers (10) includes a plurality of superimposed and coaxial luminous indicators between the first luminous indicator (1) and the watch mirror (400), each luminous indicator including a head surrounding the rotation axis (D) and a body extending substantially perpendicular to the rotation axis (D), and is characterized in that a lower indicator, which is located closer to the dial (300) than an upper indicator located immediately above the lower indicator, has at least one auxiliary hole arranged around a central hole in its head on the watch mirror (400) side so as to allow the light flux to pass through the lower indicator via the at least one auxiliary hole so that at least a portion of the light flux is absorbed by the light guide of the upper indicator.
14. The display device (100) according to one of claims 1 to 13, characterized in that The at least one light source (200) is positioned below the dial (300) near the bottom side (302) of the dial (300) facing away from the watch mirror (400) relative to the dial (300), or is embedded in the dial (300), or is positioned near the bottom side (302) of the dial (300) on a PCB (201) positioned below the dial (300).
15. The device according to claim 14, characterized in that The at least one light source (200) is a fixed illumination source comprising micro laser sources of the light emitting diode and / or organic light emitting diode and / or VCSEL type distributed around the rotation axis (D).
16. The display device (100) according to one of claims 1 to 15, characterized in that At least one luminous indicator included in the set of coaxial pointers (10) includes at least one luminous indicator whose light guide includes fluorescent material, and is characterized in that the light source (200) is a fixed lighting source, which is arranged to illuminate all heads of the indicators included in the set of coaxial pointers (10) from below by means of a light flux that is substantially parallel to the rotation axis (D) and has a wavelength shorter than the wavelength re-emitted by the fluorescent material.
17. The display device (100) according to one of claims 1 to 16, characterized in that At least one luminous indicator included in the set of coaxial pointers (10) comprises at least two luminous indicators whose light guides comprise fluorescent materials emitting in different colors.
18. A watch (1000), comprising at least one display device (100) according to any one of claims 1 to 17, characterized in that: At least one indicator included in the set of coaxial pointers (10) is a luminous pointer.