Transparent component with a functionalised surface

Abstract

The invention relates to a transparent component (1) with a functionalised surface, wherein the surface has dimples (2) and is thereby functionalised, wherein the functionalisation of the surface is an anti-glare functionalisation and the fill area of dimples is between 20% and 95%.

Description

[0001] Transparent component with a functionalized surface

[0002] Technical area

[0003] The present invention relates to a transparent component with a functionalized surface.

[0004] State of the art

[0005] It is known that laser material processing can remove material from a component by vaporizing the material within the focus zone of the laser beam through a strong light-matter interaction. The resulting structures are called dimples.

[0006] Dimples are suitable for functionalizing the surfaces of components, whereby optical and tribological properties in particular can be influenced.

[0007] However, when processing a material with a pulsed laser, regular structures often arise, for example, due to a oscillation between the repetition rate of the laser system and other process parameters such as the feed rate and the number of repetitive passes. Such regular structures can, for example, lead to interference effects that disrupt the optical appearance of the processed material.

[0008] EP 3 613 228 A1 discloses a method and a device for laser cutting, in particular for laser cutting of stents.

[0009] A method for structuring a substrate surface is known from DE 10 2017 006 358 A1.

[0010] A machining process with a random trigger function for an ultrashort pulse laser is known from US 2018 / 0207748 A1.

[0011] Description of the invention Starting from the known prior art, it is an object of the present invention to provide an improved transparent component with a functionalized surface.

[0012] The problem is solved by a transparent component having the features of claim 1. Advantageous further developments emerge from the subclaims, the description, and the figures.

[0013] Accordingly, a transparent component with a functionalized surface is proposed, wherein the surface has dimples and is thus functionalized. According to the invention, the surface functionalization is an anti-glare functionalization.

[0014] The transparent material of the component can be a material such as a polymer or a plastic. The material to be processed can also be a semiconductor, for example an elementary 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, with each layer being 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.

[0015] Transparent can mean that the component is optically transparent, i.e., transparent to wavelengths visible to the human eye. For example, the material can transmit more than 80%, more than 85%, more than 90%, more than 95%, or more than 99% of visible light. Transparent can also mean that the material is transparent to the wavelength of a laser.

[0016] The dimples can be manufactured using a laser processing method. A laser provides the laser pulses of the laser beam, with the individual laser pulses forming the 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.

[0017] This allows a laser wavelength to be selected at which the material is transparent, allowing the dimples to be introduced into the material via a nonlinear interaction. Furthermore, the short pulse duration prevents unwanted heating of the material, which can lead to undesirable material stresses. Furthermore, the laser can have linear polarization; for example, the degree of polarization of the laser beam can be more than 80%, preferably more than 95%. However, the laser beam can also have circular or elliptical polarization.

[0018] Instead of individual laser pulses, the laser can also provide laser bursts, with each burst comprising the emission of several laser pulses. For a specific time interval, the laser pulses can be emitted very closely one after the other, at intervals of a few picoseconds to nanoseconds. Laser bursts can, in particular, be GHz bursts, with the sequence of consecutive laser pulses in the GHz range. For example, a burst can comprise between 2 and 10 laser pulses, with the time interval between the laser pulses being between 10 ns and 50 ns. However, a burst can also comprise between 30 and 300 laser pulses, with the time interval between the laser pulses being between 100 ps and 1000 ps.

[0019] For example, the length of the laser pulses can be between 100ps and 100ns, in particular between 1 ns and 20ns, wherein the wavelength can be between 300nm and 550nm, in particular 355nm, wherein the repetition rate of the laser pulses can be between 10kHz and 100kHz, in particular between 10kHz and 50kHz, wherein the laser pulses can have an energy between 60pJ and 300pJ and 1 to 4 pulses can be emitted per spot.

[0020] For example, the length of the laser pulses can be between 200 fs and 1000 fs, in particular between 300 fs and 450 fs, wherein the wavelength can be between 900 nm and 2300 nm, in particular 1030 nm, wherein the repetition rate of the laser pulses can be between 10 kHz and 400 kHz, wherein the laser pulses are emitted in laser bursts, wherein each laser burst can contain between 2 and 4 laser pulses, wherein the laser bursts can have an energy between 100 pJ and 400 pJ and the numerical aperture can be between 0.01 and 0.2, in particular 0.08.

[0021] The laser pulses are introduced into the material, whereby the energy of the laser beam is at least partially absorbed in the material, for example by nonlinear interactions, in particular by multiphoton processes.

[0022] The focus 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 within the volume of the material to be processed. The focus position can also be exactly on the surface of the material to be processed. In particular, the focus position can be within ten times the Rayleigh length from the surface, where the Rayleigh length is the distance along the optical axis that a laser beam needs for its cross-sectional area to double, starting from the beam waist or focus.

[0023] In particular, the term "focus" can generally be understood as a targeted intensity increase, whereby the laser energy converges into a "focus region." Therefore, the term "focus" is used below regardless of the actual beam shape used and the methods used to achieve the intensity increase. "Focusing" can also influence the location of the intensity increase along the beam propagation direction. For example, the intensity increase can be point-like, and the focus region can have a Gaussian intensity cross-section, as provided by a Gaussian laser beam. The intensity increase can also be linear, resulting in a Bessel-shaped focus region around the focus position, as can be provided by a non-diffracting beam.Furthermore, other more complex beam shapes are possible whose focus position extends in three dimensions, such as a multi-spot profile of Gaussian laser beams and / or non-Gaussian intensity distributions.

[0024] The absorbed energy of the laser beam heats the material according to the intensity distribution of the laser and / or enters a temporary plasma state due to the electromagnetic interaction of the laser with the material. In particular, in addition to linear absorption processes, non-linear absorption processes can also be used, which become accessible through the use of high laser energies or laser intensities. The material is therefore modified particularly at the focus of the laser, since this is where the intensity of the laser beam is greatest. In particular, this can result in part of the material being released from the composite material, for example by melting or evaporating it. This enables known processing processes regarding the interaction between the laser light and the material to be processed, such as laser drilling, percussion drilling or laser ablation.

[0025] The interaction of the laser pulses with the material to be processed creates dimples on the surface of the transparent component.

[0026] A dimple is created by the evaporation of material on the surface due to the incident laser intensity. The material is evaporated particularly where the intensity of the laser beam exceeds a critical, material-specific processing threshold. Accordingly, the shape and form of the laser beam, in particular the beam profile, are crucial for the shape and form of the dimple. In the simplest case, the laser beam is a Gaussian laser beam with a Gaussian beam profile. Around the focal point there is a certain spatial region in which the laser energy lies above the critical threshold. In other words, there is an isointensity area in the intensity distribution of the laser beam at the focus within which the material can be evaporated. This isointensity area determines the shape and form of the dimple.

[0027] In particular, dimples can have a round or elliptical cross-section in the plane of the material surface, with the dimples increasing in depth from the edge to the center. In particular, the cross-section of the dimples in the plane perpendicular to the surface can also be round or rounded.

[0028] By applying dimples to the surface of the material, the optical properties of the material can be determined, for example, by scattering light passed through a transparent material at the dimples, thus making the material appear diffuse and / or matte. In particular, dimples on the surface of the material can reduce reflection from the material.

[0029] For example, the type and shape of the dimples, as well as their distribution on the surface of the component, can be used to adjust the feel or roughness. It is also possible to adjust the light scattering and thus the optical properties of the material.

[0030] Anti-glare functionalization can then consist of an incident light beam being reflected from the surface not only at the angle of reflection according to Snell's law of refraction. In particular, the incident light beam can also be reflected or scattered from the surface at other angles. In particular, this directs the incident light beam in different spatial directions, preventing a sharp reflection from occurring, in the sense that the entire energy of the incident light beam can be detected at a specific angle of reflection. Rather, the energy of the incident light is distributed across a spatial region, allowing the energy of the incident light beam to be detected within a range of angles of reflection.

[0031] The dimples can be randomly arranged on the surface.

[0032] A random arrangement can occur if the spatial distances between the dimples are randomly sized. The spatial distances result, for example, from the center-to-center distances or the minimum distances from dimple edge to dimple edge. In particular, the spatial distribution of the dimples, including the size of the dimples, results in a spatial frequency distribution of the dimples via a Fourier transformation. The more irregular the distances between the dimples, the larger the bandwidth of the spatial frequency distribution and the more diffusely an incident light beam is reflected by the transparent component.

[0033] In particular, "randomly arranged" can therefore mean that the dimples are randomly distributed in spatial frequency domain. By visualizing the position of the dimples in spatial frequency domain, it is also possible to identify potential spatial directions along which interference of the reflected or transmitted light could occur, thus optimizing the arrangement.

[0034] Randomly distributed can also mean that the spatial distribution of the dimples follows a random distribution, for example a uniform distribution.

[0035] This has the advantage that the dimples are introduced into the material at an irregular distance from one another, so that disturbing optical effects, such as interference, are reduced or avoided.

[0036] For example, the transparent component can be used to prevent a moiré effect, such as when the material is placed over a display panel with an underlying pixel array. The moiré effect typically occurs when the pixel period of the display panel is on the order of the period of the dimple array. By randomly arranging the dimples on the surface of the material, a moiré effect can be avoided because the pixel period does not create a beat with a dimple period.

[0037] The functionalized surface can be designed to reduce direct reflection.

[0038] Direct reflection, for example, is zero-order diffraction at the dimples on the surface of the transparent component. Direct reflection is suppressed if, at the angle of reflection according to Snell's law of refraction, less than 90%, preferably less than 70%, and particularly preferably less than 50%, of the incident light is reflected.

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

[0040] Sparkle describes an optical effect that manifests as a glittering or sparkling effect on a transparent component when light is reflected from the surface of the component or transmitted through the transparent component. The appearance depends heavily on the chosen angle of incidence of the light and the angle of observation. Sparkle is thus a measure of irregular fluctuations in intensity and color. Sparkle can be quantified, for example, as the intensity modulation of the light by the sparkle, specifically the intensity increase or decrease in intensity under uniform illumination.

[0041] Anti-glare functionalization can suppress such sparkle and homogenize transmission and reflection.

[0042] For example, if the transparent component is placed over a display with a particularly high resolution, it is advantageous to reduce the size of the dimples to ensure low sparkle. In particular, the size of the dimples can be smaller than the size of the pixels.

[0043] The Distinctness of Image can be more than 70%.

[0044] The Distinctness of Image (DOI) describes image sharpness and quantifies the deviation from theoretical light propagation due to the scattering of light by the dimples. A high DOI, in particular, means high image sharpness. The scattering of light by the dimples influences both the transmission and the reflection of the light at or through the surface. With a low DOI, there is a large scattering of the light, whereas with a high DOI there is little scattering of the light, thus enabling high image sharpness. The DOI therefore scales inversely with the scattering or diffusion. In particular, the DOI can also be adjusted via the so-called area coverage of the surface with dimples (see below).

[0045] Diffusion can be more than 22%.

[0046] Diffusion is a measure of the scattering power of the material. In particular, diffusion also depends on the shape and properties of the individual dimples, so diffusion can be adjusted via the beam shape of the laser beam and the size and depth of the dimples.

[0047] The dimples can have a depth between 100nm and 2000nm, preferably between 200nm and 1000nm.

[0048] This allows for a particularly advantageous adjustment of the surface roughness while avoiding significant material weakening. However, the depth of the dimples can also be used to adjust the sparkle, the DOI, and the diffusion. The dimples can have a diameter between 3 μm and 30 μm, preferably between 3 μm and 10 μm. However, the dimples can also have a diameter between 13 and 20 μm.

[0049] The sparkle, DOI and diffusion can be easily adjusted using the diameter of the dimples.

[0050] In particular, the diameter of the dimples can be used to optimize the anti-glare functionalization for any underlying optical structures, such as pixels of displays.

[0051] The dimples can vary in size from 5% to 80% of the diameter.

[0052] For example, the size variation can be 50% and the dimple diameter 20 μm. Then, the dimples can be present on the surface with diameters between 10 μm and 30 μm. The sparkle, DOI, and diffusion can be adjusted using the dimple diameter.

[0053] The roughness of the transparent component can be between 0.05pm and 1.5pm.

[0054] This can create a particularly high-quality haptic impression of the surface.

[0055] Surface roughness can be defined as a peak-to-valley value, i.e., the distance from the highest elevation to the lowest depression. However, roughness can also be defined as the standard deviation of the depth of the dimples.

[0056] The area filling of the surface with dimples can be between 20% and 95%.

[0057] The surface fill is determined by the ratio of the processed surface area by the dimples to the total surface area of ​​the transparent component. Depending on the desired roughness or desired diffusion of the transparent component, the surface fill can be adjusted.

[0058] In particular, when machining the surface, the dimples can also be introduced successively or in several passes, whereby the surface coverage is successively increased, thereby reducing distortion or smearing of the dimples.

[0059] In particular, at least two dimples can spatially overlap. Spatial overlap can mean that the dimples touch at the edge, or that the dimples partially overlap, meaning that a surface intersection of the dimples exists.

[0060] In a preferred embodiment of the transparent component, the sparkle of the surface with the anti-glare functionalization is less than 5%, the distinctness of image is more than 70% and the diffusion is more than 22%, wherein the dimples have a depth between 100nm and 2000nm, a diameter between 3pm and 30pm and a size variation to the diameter between 5% and 80%, wherein the roughness of the functionalized surface is between 0.05 and 1.5pm and the area filling with dimples is between 20% and 95%.

[0061] In a particularly preferred embodiment of the transparent component, the sparkle of the surface with the anti-glare functionalization is less than 5%, the distinctness of image is more than 70% and the diffusion is more than 22%, wherein the dimples have a depth between 200nm and 1000nm, a diameter between 3pm and 10pm and a size variation to the diameter between 5% and 80%, wherein the roughness of the functionalized surface is between 0.05 and 1.5pm and the area filling with dimples is between 20% and 95%.

[0062] The transparent component can be a cover or protective part of a smart device.

[0063] In particular, so-called smart devices could be electronic devices that are touch-sensitive and can be controlled by finger gestures, for example smartwatches, smartphones, tablets, but also image display devices in cars, etc. In general, screens and displays are included in smart devices.

[0064] However, it is also possible that the transparent component is located on the back of a smart device and gives the back a particularly high-quality and non-slip surface finish thanks to its matte surface and the roughness created by the dimples.

[0065] The transparent component can be arranged over a pixel matrix of a display of a smart device, with the dimples being smaller than the pixels.

[0066] For example, the transparent component can be arranged above the active matrix of a display panel, with the active matrix comprising electronically controllable pixel points that together form the display image. The transparent component can thus protect and cover the underlying active matrix from mechanical influences.

[0067] By making the dimple size, especially the dimple diameter, smaller than the pixel size, a moiré effect can be avoided. Brief description of the figures

[0068] Preferred further embodiments of the invention are explained in more detail in the following description of the figures. In the figures:

[0069] Figure 1 shows a microscopic image of a transparent component with anti-glare functionalization; and

[0070] Figure 2 shows a confocal microscope image of a transparent component with anti-glare functionalization.

[0071] Detailed description of preferred embodiments

[0072] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are provided with identical reference numerals, and a repeated description of these elements is partially omitted to avoid redundancies.

[0073] Figure 1 shows a microscope image of a transparent component 1 with a surface functionalized with dimples 2, where the functionalization is anti-glare. So-called dimples 2 were imprinted 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 dimples 2 are noticeable as round to oval ablated defects in the surface of the transparent component. In particular, each dimple 2 can be created individually by two laser pulses of a laser burst.

[0074] The transparent material of component 1 can be, for example, sapphire or quartz glass.

[0075] As can be seen in Figure 1, the dimples 2 are arranged randomly on the component, whereby the dimples 2 can also partially overlap or be adjacent to one another. By applying the dimples 2 in an irregular pattern to the surface of the transparent component 1, the direct reflection of an incident light beam can be suppressed, since the incident light beam is refracted by the dimples 2 into a plurality of partial beams and reflected away.

[0076] Through such a modification of the surface by the dimples 2, the sparkle of the surface with the anti-glare functionalization can be less than 5%, the distinctness of image more than 70%, and the diffusion more than 22%. The same transparent component 1 is shown in the dimensioned confocal microscope image in Figure 2. The dimples have a depth between 100 nm and 2000 nm, for example, 500 nm. The dimples also have a diameter between 3 pm and 30 pm, for example, 20 pm. The dimples also have a size variation relative to the diameter between 5% and 80%, for example, 10%. In addition, the area filling of the surface with the dimples 2 is between 20% and 95%, for example, 30%.

[0077] These values ​​make it particularly easy to adjust the parameters for sparkle, DOI and diffusion.

[0078] For example, the transparent component 1 can be arranged on the display panel of a smart device, so that the transparent component 1 functions as a protective or covering layer. In particular, the haptic quality can also be adjusted by the roughness of the transparent component through the dimple size. Furthermore, the formation of a moiré effect can be avoided by a random arrangement of the dimples 2 and / or a dimple size that is smaller than the pixel size (not shown). Where applicable, all individual features presented in the exemplary embodiments can be combined and / or exchanged with one another without departing from the scope of the invention.

[0079] List of reference symbols

[0080] 1 transparent component

[0081] 2 dimples

Claims

Claims 1 . Transparent component (1) with a functionalized surface, wherein the surface has dimples (2) and is thereby functionalized, characterized in that the functionalization of the surface is an anti-glare functionalization and that the area filling with dimples (2) is between 20% and 95%.

2. Transparent component (1) according to claim 1, characterized in that the dimples (2) are arranged randomly on the surface.

3. Transparent component (1) according to claim 1 or 2, characterized in that the surface reduces direct reflection.

4. Transparent component (1) according to one of the preceding claims, characterized in that the sparkle of the surface with the anti-glare functionalization is less than 5%.

5. Transparent component (1) according to one of the preceding claims, characterized in that the distinctness of image is more than 70%.

6. Transparent component (1) according to one of the preceding claims, characterized in that the diffusion is more than 22%.

7. Transparent component (1) according to one of the preceding claims, characterized in that the dimples (2) have a depth between 100nm and 2000nm, preferably a depth between 200nm and 1000nm.

8. Transparent component (1) according to any preceding claim, characterized in that the dimples (2) have a diameter between 3pm and 30pm, preferably a diameter between 3pm and 10pm.

9. Transparent component (1) according to one of the preceding claims, characterized in that the dimples (2) have a size variation to the diameter between 5% and 80%. Transparent component (1) according to one of the preceding claims, characterized in that the roughness of the functionalized surface is between 0.05 and 1.5 pm. Transparent component (1) according to one of the preceding claims, characterized in that at least two dimples spatially overlap. Transparent component (1) according to one of the preceding claims, characterized in that the transparent component is a cover or protective part of a smart device. Transparent component (1) according to 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 dimples (2) are smaller than the pixels.

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