Transparent component with functionalized surface

Abstract

The invention relates to a transparent component (1) having a functionalized surface, the surface having recesses (2) and being functionalized thereby, the functionalization of the surface being anti-glare functionalization, and the surface filling of the recesses being between 20% and 95%.

Description

Technical Field

[0001] The invention relates to a transparent component having a functionalized surface. Background Art

[0002] It is well known that during laser material processing, material can be removed from a component by vaporizing the material in the focal region of the laser beam through the interaction of intense light with matter. The resulting structure is called a dimple.

[0003] In this respect, the recesses are suitable for functionalizing the surface of the component, wherein, in particular, the optical and tribological properties can be influenced.

[0004] However, when processing materials using pulsed lasers, a regular structure is often created, for example by the beat frequency between the repetition frequency of the laser system and other processing parameters, such as the feed rate and the number of repetitions of the material pass. For example, such a regular structure may lead to disturbing effects that disrupt the visual impression of the processed material.

[0005] A method and a device for laser cutting, in particular for laser cutting of stents, are known from EP 3 613 228 A1.

[0006] A method for structuring a substrate surface is known from DE 10 2017 006 358 A1.

[0007] A processing process with an ultrashort pulse laser having a random triggering function is known from US 2018 / 0207748 A1. Summary of the invention

[0008] Starting from the known prior art, it is an object of the present invention to provide an improved transparent component with a functionalized surface.

[0009] This object is achieved by a transparent component having the features of claim 1. Advantageous embodiments emerge from the dependent claims, the description and the figures.

[0010] Therefore, a transparent component with a functionalized surface is proposed, wherein the surface has recesses and the surface is functionalized. According to the invention, the surface functionalization is an anti-glare functionalization.

[0011] Here, the transparent material of the component can be, for example, a material such as a polymer or a plastic. The material to be processed can also be a semiconductor, for example, an elemental semiconductor such as silicon or germanium, or a III-V semiconductor such as gallium arsenide, or an organic semiconductor or any other type of semiconductor. For example, the material can be a silicon wafer. In particular, the material can be a layer system, wherein each layer can be selected from the group of metals, polymers, plastics or semiconductors. In particular, the material can also be a glass, for example sapphire or quartz glass.

[0012] "Transparent" may mean that the component is optically transparent, i.e., transparent with respect to wavelengths visible to the human eye. For example, the material may transmit more than 80%, or more than 85%, or more than 90%, or more than 95%, or more than 99% of visible light. However, "transparent" may also mean that the material is transparent with respect to the wavelength of the laser light.

[0013] The recess can be produced using a laser processing method. Thus, the laser provides laser pulses of a laser beam, wherein the individual laser pulses form a laser beam in the beam propagation direction. The pulse duration of the laser pulses can be between 300 fs and 10 ps, ​​and / or the wavelength of the laser pulses can be between 300 nm and 3000 nm, preferably between 900 nm and 2200 nm.

[0014] This enables the selection of a laser wavelength at which the material is transparent, so that recesses can be introduced into the material through nonlinear interactions. In addition, the short pulse duration can prevent unwanted material heating that could lead to undesirable material stresses.

[0015] In addition, the laser light may have a linear polarization, for example, the polarization degree of the laser beam may be higher than 80%, preferably higher than 95%.The laser beam may also have a circular polarization or an elliptical polarization.

[0016] Instead of individual laser pulses, the laser can also provide a laser pulse train, wherein each pulse train (Burst) comprises the emission of multiple laser pulses. Therefore, the laser pulses can be emitted very quickly in succession at intervals of a few picoseconds to a few nanoseconds within a specific time interval. In particular, the laser pulse train can be a GHz pulse train, wherein the continuous laser pulse sequence of the corresponding pulse train occurs in the GHz range. For example, the pulse train can contain 2 to 10 laser pulses, wherein the time interval between the laser pulses is between 10ns and 50ns. However, the pulse train can also contain 30 to 300 laser pulses, wherein the time interval between the laser pulses can be between 100ps and 1000ps.

[0017] For example, the length of the laser pulse can be between 100ps and 100ns, in particular between 1ns and 20ns, wherein the wavelength can be between 300nm and 550nm, in particular 355nm, wherein the repetition frequency of the laser pulse can be between 10kHz and 100kHz, in particular between 10kHz and 50kHz, wherein the laser pulse can have an energy between 60μJ and 300μJ, and 1 to 4 pulses can be emitted at each point.

[0018] For example, the length of the laser pulse can be between 200fs and 1000fs, in particular between 300fs and 450fs, wherein the wavelength can be between 900nm and 2300nm, in particular 1030nm, wherein the repetition frequency of the laser pulse can be between 10kHz and 400kHz, wherein the laser pulses are emitted in laser pulse trains, wherein each laser pulse train can contain 2 to 4 laser pulses, wherein the laser pulse train can have an energy between 100μJ and 400μJ, and the numerical aperture can be between 0.01 and 0.2, in particular 0.08.

[0019] The laser pulses are introduced into the material, wherein the energy of the laser beam is at least partially absorbed into the material, for example by nonlinear interactions, in particular by multiphoton processing.

[0020] In this case, the focal point of the laser beam can be located above the surface of the material to be processed in the direction of beam propagation, or below the surface in the volume of the material to be processed. The focal position can also be located exactly on the surface of the material to be processed. In particular, the focal position can be within ten times the Rayleigh length from the surface, wherein the Rayleigh length is the distance along the optical axis that the laser beam needs to travel from the beam waist or focus until its cross-sectional area doubles.

[0021] In particular, the term "focus" may generally be understood as a targeted increase in intensity, wherein the laser energy is concentrated in a "focal region". In particular, the term "focus" is therefore used below without taking into account the actual beam shape used and the method used to cause the intensity increase. By "focusing", it is also possible to influence the position of the intensity increase along the beam propagation direction. For example, the intensity increase can be almost point-shaped and the focal region can have a Gaussian-shaped intensity cross-section, as provided by a Gaussian laser beam. The intensity increase can also be linear, wherein a Bessel-type focal region is created around the focal position, as can be provided by a non-diffracting beam. In addition, other more complex beam shapes are also possible, whose focal position extends in three dimensions, such as a multi-point profile of a Gaussian laser beam and / or a non-Gaussian intensity distribution.

[0022] Due to the energy absorbed from the laser beam, the material heats up depending on the intensity distribution of the laser and / or is transformed into a temporary plasma state depending on the electromagnetic interaction between the laser and the material. In particular, in addition to linear absorption processes, nonlinear absorption processes can also be used, which become achievable by using high laser energies or laser intensities. The material is thus modified in particular at the focus of the laser, since this is where the intensity of the laser beam is greatest. In particular, this can be achieved in that some of the material can be released from the material composite, for example by melting it or vaporizing it. Therefore, with regard to the interaction between the laser and the material to be processed, machining processes known per se are possible, these methods being known, for example, as laser drilling, percussion drilling or laser ablation.

[0023] The interaction of the laser pulses with the material to be processed produces recesses in the surface of the transparent component.

[0024] The recesses are produced by vaporizing the material on the surface due to the intensity of the irradiated laser. In particular, the material is vaporized when the intensity of the laser beam is above a critical processing threshold specific to the material. Therefore, the shape and form of the laser beam, in particular the beam profile, are crucial for the shape and form of the recesses.

[0025] In the simplest case, the laser beam is a Gaussian laser beam with a Gaussian beam profile. There is a certain spatial region around the focus in which the laser energy is above a critical threshold. That is, there is an iso-intensity surface in the intensity distribution of the laser beam at the focus, and the material within the iso-intensity surface can be vaporized. The shape and morphology of the concave portion are caused by the iso-intensity surface.

[0026] In particular, therefore, the recess can have an annular or elliptical cross section in the plane of the material surface, wherein the recess has a depth that increases gradually from the edge to the center. In particular, the cross section of the recess in a plane perpendicular to the surface can also be circular or rounded.

[0027] By introducing recesses on the surface of the material, the optical properties of the material can be determined, for example by scattering light passing through the transparent material at the recesses, so that the material appears diffuse and / or matte. In particular, the recesses on the surface of the material can reduce reflections from the material.

[0028] For example, the tactile feel or the roughness can be adjusted by the type and shape of the recesses and their distribution over the component surface. However, it is also possible to adjust the scattering of light and thus the optical properties of the material.

[0029] Then, the anti-glare functionalization may include that the incident beam is reflected from the surface not only at the reflection angle according to Snell's refraction law. In particular, it may also be the case that the incident beam is reflected or scattered from the surface at other angles. In particular, the incident beam is directed to different spatial directions so that no sharp reflection occurs, so that the entire energy of the incident beam can be detected at a specific angle of incidence. Instead, the energy of the incident light is distributed over a spatial area so that the energy of the incident beam can be detected within a range of reflection angles.

[0030] The recesses may be randomly arranged on the surface.

[0031] A random arrangement occurs if the spatial distances between the recesses are of random size. The spatial distances are given by the center distance or the shortest distance from recess edge to recess edge.

[0032] Specifically, for example, the spatial frequency distribution of the recesses is derived from the spatial distribution of the recesses (including the recess sizes) by Fourier transformation. The more irregular the distance between the recesses, the larger the bandwidth of the spatial frequency distribution, and the more diffusely the incident beam is reflected by the transparent component.

[0033] In particular, "randomly arranged" may mean that the recesses are randomly distributed in the spatial frequency space. By displaying the positions of the recesses in the spatial frequency domain, potential spatial directions along which reflected or transmitted light interference may occur may also be identified in order to optimize the arrangement.

[0034] “Randomly distributed” may also mean that the spatial distribution of the recesses follows a random distribution, such as a uniform distribution.

[0035] This has the advantage that the recesses are introduced into the material at irregular distances from one another, so that, for example, disruptive optical effects such as interference are reduced or avoided.

[0036] For example, when the material is placed over a display panel with an underlying pixel grid, for example, the transparent component can be used to avoid the moiré effect. The moiré effect typically occurs when the pixel period of the display panel is of the same order of magnitude as the period of the recess arrangement. By randomly arranging the recesses on the surface of the material, the moiré effect can be avoided because the pixel period does not produce a beat frequency with the recess period.

[0037] Functionalized surfaces can be designed to reduce direct reflections.

[0038] For example, direct reflection is the zeroth order diffraction at a concave portion of the surface of the transparent component. Direct reflection is suppressed if less than 90%, preferably less than 70%, particularly preferably less than 50% of the incident light is reflected at a certain reflection angle according to Snell's refraction law.

[0039] The sparkle of a surface with anti-glare functionalization may be less than 5%.

[0040] "Sparkle" describes the optical effect whereby a transparent component visibly sparkles or shimmers when light is reflected from the surface of the component or transmitted through it. This phenomenon depends strongly on the chosen angle of incidence of the light and the angle of observation. Sparkle is therefore a measure of irregular intensity and color fluctuations.

[0041] The sparkle may, for example, be quantified as the intensity modulation of the light by the flash, in particular an intensity increase or intensity decrease under uniform illumination.

[0042] With the aid of anti-glare functionalization, this glare can be suppressed, and transmission and reflection can be homogenized.

[0043] For example, if the transparent component is placed above a display with particularly high resolution, it is advantageous to reduce the size of the recess to ensure a slight sparkle. In particular, the size of the recess may be smaller than the size of a pixel.

[0044] Image clarity can be higher than 70%.

[0045] Distinction of Image (DOI) describes image sharpness And quantifies the deviation from the theoretical light propagation due to light scattering at the recesses. "High DOI" means in particular high image sharpness. Light scattering at the recesses influences both the reflection of light at the surface or the transmission through the surface. In the case of a low DOI, the light scattering is large, while in the case of a high DOI, the light scattering is small and therefore a high image sharpness is possible. The DOI is therefore inversely proportional to the scattering or diffusion. In particular, the DOI can also be set by the so-called area coverage of the surface with recesses (see below).

[0046] The diffusion can be higher than 22%.

[0047] The diffuseness is a measure of the scattering intensity of a material. In particular, the diffuseness also depends on the shape and properties of the individual recesses, so that the diffuseness can be adjusted by the beam shape of the laser beam and the size and depth of the recesses.

[0048] The recess may have a depth between 100 nm and 2000 nm, preferably between 200 nm and 1000 nm.

[0049] This makes it particularly advantageous to adjust the roughness of the surface while avoiding substantial weakening of the material. However, the depth of the recesses can also be used to adjust the sparkle, DOI and diffuseness.

[0050] The recess can have a diameter between 3 μm and 30 μm, preferably between 3 μm and 10 μm. The recess can also have a diameter between 13 μm and 20 μm.

[0051] Sparkle, DOI and diffuseness can be adjusted particularly easily using the diameter of the recesses.

[0052] In particular, the diameter of the recesses can be used to optimize the anti-glare functionalization of any underlying optical structures, such as pixels of a display.

[0053] The recesses may have a size variation of between 5% and 80% of the diameter.

[0054] For example, the size variation may be 50% and the diameter of the recess may be 20 μm. The recesses on the surface may then have a diameter between 10 μm and 30 μm. The sparkle, DOI and diffuseness may be adjusted by the diameter of the recesses.

[0055] The roughness of the transparent part may be between 0.05 μm and 1.5 μm.

[0056] This can produce a particularly high-quality tactile impression of the surface.

[0057] Surface roughness can be defined as the peak-to-valley value, i.e., the distance from the highest protrusion to the lowest valley. However, surface roughness can also be defined as the standard deviation of the depth of the valleys.

[0058] The surface filling of the surface with the recesses can be between 20% and 95%.

[0059] The area filling of the surface is given by the area ratio of the processed surface through the recesses to the total surface of the transparent part. Depending on the desired roughness or the desired diffuseness of the transparent part, the area filling of the surface can be adjusted.

[0060] In particular, when machining a surface, it is also possible to do so continuously or in several passes ( ) wherein recesses are introduced into the surface, wherein the surface coverage increases continuously while the distortion or smearing of the recesses decreases.

[0061] In particular, at least two recesses can overlap spatially.

[0062] “Spatially overlapping” can mean that the recesses touch at the edges or that the recesses lie partially on top of one another, ie there is a surface intersection of the recesses.

[0063] In a preferred embodiment of the transparent component, the sparkle of the surface with anti-glare functionalization is less than 5%, the image clarity is higher than 70% and the diffuseness is higher than 22%, wherein the recesses have a depth between 100nm and 2000nm, a diameter between 3μm and 30μm, and a size variation with respect to the diameter between 5% and 80%, wherein the roughness of the functionalized surface is between 0.05μm and 1.5μm and the surface filling with the recesses is between 20% and 95%.

[0064] In a particularly preferred embodiment of the transparent component, the sparkle of the surface with anti-glare functionalization is less than 5%, the image clarity is greater than 70% and the diffuseness is greater than 22%, wherein the recesses have a depth between 200nm and 1000nm, a diameter between 3μm and 10μm, and a size variation with respect to the diameter between 5% and 80%, wherein the roughness of the functionalized surface is between 0.05μm and 1.5μm and the surface filling with the recesses is between 20% and 95%.

[0065] The transparent component may be a covering portion or a protective portion of the smart device.

[0066] In particular, the so-called smart device may be an electronic device that is touch-sensitive and controllable by finger gestures, such as a smart watch, a smart phone, a tablet computer, or an image display device in a car, etc. Generally, the smart device includes a screen and a display.

[0067] However, it may also be the case that the transparent component is arranged on the rear side of the smart device and provides the rear side with a particularly high-quality and non-slip surface finish due to its matte surface and the roughness caused by the recesses.

[0068] The transparent component may be arranged over a pixel matrix of a display of the smart device, wherein the recesses are smaller than the pixels.

[0069] For example, the transparent component may be arranged above the active matrix of a display panel, wherein the active matrix has electronically controllable pixels that together form the image of the display. Thus, the transparent component may protect and cover the underlying active matrix from mechanical influences.

[0070] In particular, by making the recess size, in particular the recess diameter, smaller than the pixel size, moire effects can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The preferred further embodiments of the present invention are described in more detail by the following description of the accompanying drawings. In the accompanying drawings:

[0072] Figure 1 shows a microscopic image of a transparent part with anti-glare functionalization; and

[0073] Figure 2 Confocal microscopy images of transparent components with anti-glare functionalization are shown. DETAILED DESCRIPTION

[0074] Preferred exemplary embodiments are described below with reference to the accompanying drawings. In this case, in different figures, identical, similar or elements having the same effect are provided with identical reference numerals, and repeated description of these elements is omitted in some instances to avoid redundancy.

[0075] Figure 1 A microscope image of a transparent component 1 having a surface functionalized with recesses 2 is shown, wherein the functionalization is an anti-glare functionalization. The so-called recesses 2 are embossed on the surface of the transparent component 1 by corresponding laser pulses of a laser, for example by two laser pulses of a laser pulse. The recesses 2 appear as circular to oval ablation defects on the surface of the transparent component. In particular, each recess 2 can be produced individually by two laser pulses of a laser pulse train.

[0076] The transparent material of component 1 may be, for example, sapphire or quartz glass.

[0077] like Figure 1 As can be seen in the figure, the recesses 2 are randomly arranged on the component, wherein the recesses 2 may also partially overlap or be adjacent to each other. By applying the recesses 2 in an irregular pattern to the surface of the transparent component 1, direct reflection of the incident beam can be particularly suppressed, because the incident beam is refracted by the recesses 2 into a plurality of partial beams and reflected out.

[0078] By such modification of the surface by the recesses 2, the sparkle of the surface with anti-glare functionalization can be less than 5%, the image clarity can be higher than 70%, and the diffuseness can be higher than 22%.

[0079] Figure 2 The same transparent component 1 is shown in the dimensioned confocal microscope image of FIG. The recess has a depth between 100 nm and 2000 nm, for example 500 nm. The recess also has a diameter between 3 μm and 30 μm, for example 20 μm. The recess also has a size variation with respect to the diameter of between 5% and 80%, for example 10%. In addition, the surface filling of the surface with the recess 2 is between 20% and 95%, for example 30%.

[0080] These values ​​make it particularly easy to adjust parameters for sparkle, DOI, and diffuseness.

[0081] For example, the transparent component 1 can be arranged on the display panel of the smart device so that the transparent component 1 serves as a protective layer or a cover layer. In particular, the tactile quality can be adjusted by the roughness of the transparent component caused by the size of the recesses. In addition, the formation of the moire effect can be avoided by the random arrangement of the recesses 2 and / or the size of the recesses being smaller than the pixel size (not shown).

[0082] To the extent applicable, all the individual features presented in the exemplary embodiments may be combined with one another and / or interchanged without departing from the scope of the present invention.

[0083] Reference numerals list

[0084] 1 Transparent parts

[0085] 2 concavity

Claims

1. A transparent component (1), the transparent component having a functionalized surface, wherein: The surface has recesses (2) and is functionalized thereby, It is characterized in that The functionalization of the surface is an anti-glare functionalization and the surface filling of the recess (2) is between 20% and 95%.

2. The transparent component (1) according to claim 1, characterized in that The recesses (2) are randomly arranged on the surface.

3. The transparent component (1) according to claim 1 or 2, characterized in that: The surface reduces direct reflections.

4. The transparent component (1) according to any one of the preceding claims, characterized in that The surface having the anti-glare functionalization has a sparkle of less than 5%.

5. The transparent component (1) according to any one of the preceding claims, characterized in that Image clarity is higher than 70%.

6. The transparent component (1) according to any one of the preceding claims, characterized in that The diffuseness is higher than 22%.

7. The transparent component (1) according to any one of the preceding claims, characterized in that The recess (2) has a depth between 100 nm and 2000 nm, preferably between 200 nm and 1000 nm.

8. The transparent component (1) according to any of the preceding claims, characterized in that The recess (2) has a diameter between 3 μm and 30 μm, preferably between 3 μm and 10 μm.

9. The transparent component (1) according to any one of the preceding claims, characterized in that The recess (2) has a size variation with respect to the diameter of between 5% and 80%.

10. The transparent component (1) according to any one of the preceding claims, characterized in that The roughness of the functionalized surface is between 0.05 μm and 1.5 μm.

11. The transparent component (1) according to any one of the preceding claims, characterized in that At least two recesses overlap spatially.

12. The transparent component (1) according to any one of the preceding claims, characterized in that The transparent component is a covering part or a protecting part of the smart device.

13. The transparent component (1) according to any one of the preceding claims, characterized in that The transparent component is arranged above a pixel matrix of a display of a smart device, wherein the recess (2) is smaller than a pixel.

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