EP4295403A1

EP4295403A1 - Apparatus and method for inspecting a substrate in display manufacture and system for processing a substrate

Info

Publication number: EP4295403A1
Application number: EP21707247.9A
Authority: EP
Inventors: Giorgio Cellere; Valentina Furin; Hou T. Ng; Carlo GALLIANI
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2023-12-27
Also published as: JP2024509762A; KR20230147672A; CN116868338A; TW202238788A; WO2022174931A1

Abstract

An apparatus (100) for inspecting a substrate (10) in display manufacture is provided. The substrate has one or more sections having curable ink provided therein and the apparatus includes a substrate support (110), a stimulation source (130) for providing a stimulus at or above a first predetermined threshold to the substrate, an optical inspection device (120) for detecting a light emission emitted from the curable ink at the one or more sections, and a controller (140) for providing information about a filling status of the one or more sections calculated from the light emission detected by the optical inspection device.

Description

APPARATUS AND METHOD FOR INSPECTING A SUBSTRATE IN DISPLAY MANUFACTURE AND SYSTEM FOR PROCESSING A SUBSTRATE

FIELD OF INVENTION

[0001 ] The present disclosure is in the field of display manufacture, particularly in the field of providing a substrate for use in display applications. More particularly, the present disclosure refers to apparatuses and methods for inspecting a substrate having curable ink printed thereon.

BACKGROUND

[0002] In display manufacture, several techniques are known to provide displays with improved resolution and contrast characteristics and many approaches have been developed. Where LCDs (liquid crystal display) use light-modulating properties of liquid crystals for influencing light provided by a backlight source or reflector to produce images in color or monochrome, the technique of OLED (organic light-emitting diode) displays provides organic materials directly emitting visible light in response to an electric power. [0003] OLED displays are known to have beneficial effects in contrast to LCDs, for example, thinner and lighter displays can be provided, the OLED displays achieve deeper black levels and a higher contrast ratio as well as are flexible and transparent, thus allowing the use of OLED displays in multiple applications like screens, TVs, smartphones, etc.

[0004] The generation of OLED substrates is typically carried out by coating an organic material onto a substrate, the organic material providing the primary colors red, blue and green to generate pixels on the substrate. The coating processes can be, e.g., based on the evaporation of organic materials such as a host material and dopant materials, being deposited on the substrate, to provide for the differently colored pixels on the substrate.

[0005] In contrast to OLED technology, microLEDs (light-emitting diodes) can provide microscopic small pixels on a substrate, the microLEDs being made of inorganic materials, e.g. indium gallium nitride (InGaN), provided as semiconductor arrays, the microLEDs being capable of self-emitting light in response to an electric power. The microLED technology can be beneficial compared to the OLED technology regarding display manufacture as regards to e.g., the lifetime, brightness and contrast of the resulting displays. So far, manufacture of microLED arrays suitable for display manufacture has been expensive and inefficient. Furthermore, different approaches exist to provide colored pixels for the microLED based substrates used for displays. One approach is to provide colored ink by printing processes to the substrate for generating pixels of different colors.

[0006] In light of the above, it is beneficial to provide improved apparatuses, systems and methods for display manufacture, particularly for the manufacture including printing of the colored pixels.

SUMMARY

[0007] According to the present disclosure, an apparatus for inspecting a substrate in display manufacture is provided. The substrate has one or more sections having curable ink provided therein and the apparatus includes a substrate support, a stimulation source for providing a stimulus at or above a first predetermined threshold to the substrate, an optical inspection device for detecting a light emission emitted from the curable ink at the one or more sections, and a controller for providing information about a filling status of the one or more sections calculated from the light emission detected by the optical inspection device.

[0008] According to an aspect, a system for processing a substrate is provided. The substrate has one or more sections and the system includes a printer for providing a curable ink to the one or more sections of the substrate, and an apparatus according to embodiments described herein.

[0009] According to an aspect, a method for inspecting a substrate having one or more sections in display manufacture is provided. The method includes providing curable ink to the one or more sections to fill the one or more sections, aligning an optical inspection device and the substrate, providing a stimulus at or above a first predetermined threshold, recording a light emitted from the curable ink printed on the one or more sections of the substrate with the optical inspection device, and generating information about a filling status of the one or more sections from the light emitted from the curable ink printed on the substrate. [0010] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the present disclosure are also directed at methods for operating the described apparatus. It includes method aspects for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011 ] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

FIG. 1 shows a schematic front view of an apparatus according to embodiments described herein; FIG. 2 shows a schematic top view of a substrate according to embodiments herein; FIG. 3 shows a schematic front view of an apparatus according to embodiments described herein;

FIGs. 4 A to 4C show examples for subsections according to embodiments described herein;

FIG. 5 shows a wavelength diagram according to embodiments herein; FIG. 6 shows a schematic front view of a system according to embodiments described herein; and

FIG. 7 shows a flow diagram of a method according to embodiments described herein. DETAILED DESCRIPTION OF EMBODIMENTS

[0012] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0013] Within the following description of the drawings, the same reference numbers refer to the same or similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one applies to a corresponding part or aspect in another embodiment as well.

[0014] In display manufacture, generation of colored pixels on a substrate may be provided by printing respective ink onto the substrate. For example, latest techniques may utilize curable ink printed on a substrate to provide a high density of pixels on the substrate to provide high resolution displays. The substrate is provided with the ink and the ink is cured for fixation at the substrate.

[0015] Highly accurate printing of the ink is required to obtain high yields in production and high-quality substrates. In particular, in the field of microFED-based displays, where single pixels include sizes in the mhi-range, accuracy of printing is beneficial. This may include not only the position where the ink is provided, e.g. printed on the substrate but also the amount of ink provided. Accordingly, approaches for providing ink to the substrate, e.g. printing approaches, may be subject to quality checks since the amount of ink provided and printing accuracy can vary over time and may negatively impair printing results.

[0016] In light of the above, it is beneficial to provide apparatuses, methods and systems for inspecting a substrate provided with, e.g. printed with, curable ink to ensure high quality and high yield in display manufacture. [0017] According to embodiments that can be combined with any other embodiment described herein and with exemplary reference to FIG. 1, an apparatus 100 for inspecting a substrate 10 in display manufacture is provided. The substrate includes one or more sections having curable ink provided therein. The apparatus includes a substrate support 110. Further, the apparatus includes a stimulation source 130 for providing a stimulus at or above a first predetermined threshold to the substrate. Additionally, the apparatus includes an optical inspection device 120 for detecting a light emission emitted from the curable ink at the one or more sections and a controller 140 for providing information about a filling status of the one or more sections calculated from the light emission detected by the optical inspection device.

[0018] According to embodiments that can be combined with any other embodiment described herein, a substrate may be provided at the substrate support 110. The substrate is further described with exemplary reference to FIG. 2. The substrate may be a glass substrate. Additionally, or alternatively, the substrate may further include a polymeric material. The substrate may be made of a polymeric material. The substrate may include and/or be made of a flexible polymeric material. The substrate may be provided to the substrate support automatically, e.g. by a transfer device or the like. The substrate support may include non- reflective properties, e.g. the substrate support may be transparent or may include a dark color such that the substrate support may prevent interference with the stimulus provided by the stimulation source to the substrate, e.g. with light provided by a light source.

[0019] According to embodiments that can be combined with any other embodiment described herein, the stimulation source 130 may stimulate emission of light of the curable ink. The stimulation source may be configured to irradiate the substrate. The stimulation source 130 may be configured to provide energy to the curable ink provided on the substrate. Stimulation of the curable ink may be provided by light, thermal impact and/or by electrical impact. For example, the stimulation source 130 may be configured to provide a light at or above a predetermined wavelength to the substrate. Particularly, the stimulation source may be configured to provide a light at a wavelength that may excite the curable ink printed on the substrate. Accordingly, the stimulation source 130 may be a light source. The light source may be a wide spectrum source.

Additionally, or alternatively, the light source may include LEDs to provide light of (a) particular wavelength(s). The curable ink provided on the substrate may emit a light at a wavelength different from the wavelength provided to the substrate from the stimulation source 130, i.e. from the light source. More particularly, the light source may provide a light having a wavelength that excites the curable ink while preventing initiation of a curing reaction of the curable ink. The curable ink may be a light-curable ink.

[0020] According to embodiments that can be combined with any other embodiment described herein, the inspection device 120 may detect the light emitted from the substrate. The optical inspection device may be configured to detect a light intensity, e.g. a gray-scale value, and/or a color intensity or brightness emitted by the substrate, i.e. by the curable ink provided at the substrate. The optical inspection device may be movably arranged at the apparatus. The inspection device 120 may be attached to a holding arrangement 126. The holding arrangement 126 may be movable to inspect various areas of the substrate. For example, the holding arrangement may be movable such that the optical inspection device may inspect a plurality of rows and/or a plurality of columns of the substrate. Additionally, or alternatively, the substrate support may be movable to arrange the substrate and the inspection device for proper inspection.

[0021 ] According to embodiments that can be combined with any other embodiment described herein, the apparatus may include a controller 140 for providing information about a filling status of the one or more sections calculated from the light emission detected by the optical inspection device. In particular, the controller may be configured to obtain the information about the filling status from a light intensity and/or brightness of the emitted light from the curable ink. Additionally, or alternatively, the controller may be configured to obtain the information about the filling status from a gray-scale value of the light emitted by the curable ink provided at the one or more sections. The term “gray-scale value” as used herein may be understood as a value being a measure of the brightness and/or intensity of light detected from a section of the one or more sections. A section of the one or more sections of the substrate may be regarded as a pixel. For example, one gray-scale value can be provided for each of the detected one or more sections, i.e. one gray-scale value may be provided for each pixel on the substrate. Additionally, or alternatively, the controller may be configured to obtain the information about the filling status from a color intensity and/or color brightness of the emitted light from the curable ink.

[0022] The term “filling status” as used herein may be understood as information about the presence of ink at the substrate, i.e. in the one or more sections or as information about the amount of ink present at the substrate, i.e. in the one or more sections. Accordingly, the term “filling status” may include qualitative and/or quantitative information about the curable ink.

[0023 ] According to embodiments that can be combined with any other embodiment described herein and with exemplary reference to FIG. 2, the substrate 10 includes one or more sections 12. The one or more sections may be arranged in a matrix. The one or more sections may provide a grid. The one or more sections may be squares. For example, the one or more sections may have an extension in an x-direction and an extension in an y-direction of a cartesian coordinate system (as exemplarily shown in FIG. 2). The extension in the x- and the y-direction may have the same magnitude, i.e. the one or more sections may include a width and a length of a same dimension. As an example, the extension in the x- and the y-direction, i.e. the width and the length of one section, may include dimensions in the range of 1 Omhi to 50 pm, particularly in the range of 20 to 40 pm, more particularly 30 pm. For example, each of the one or more sections may have a length of 30 pm and a width of 30 pm. The one or more sections may each include a depth in the direction of the paper plane of FIG. 2. The depth may define a filling height of the one or more sections. The depth of the one or more sections may be in a range of 0.1 mm to 1 mm, particularly 0.3 mm to 0.8 mm, more particularly of 0.5 mm.

[0024] According to embodiments that can be combined with any other embodiment described herein, the substrate may include a plurality of sections. The plurality of sections may be arranged in a plurality of rows 16 and a plurality of columns 18. The plurality of rows may include the plurality of sections arranged in the x-direction of the cartesian coordinate system shown in FIG. 2 and the plurality of columns may include the plurality of sections arranged in the y-direction of the cartesian coordinate system shown in FIG. 2.

[0025] According to embodiments that can be combined with any other embodiment described herein, the substrate may particularly include a plurality of sections, e.g. the substrate may include more than 10 M (million) sections, particularly more than 20 M sections, more particularly 30 M or more sections. According to embodiments, the substrate may have an overall size of 240 mm x 320 mm. Each of the one or more sections may represent one pixel on the substrate. [0026] According to embodiments that can be combined with any other embodiment described herein, the one or more sections may be clustered into subsections 14. A subsection 14 may include four of the one or more sections as indicated by the dotted line in FIG. 2. The cluster or subsection may include four of the one or more sections arranged in a 2 x 2 matrix or square. Accordingly, each cluster or subsection may include four sections, two of the sections being arranged above or below the other two sections of the same cluster or subsection.

[0027] According to embodiments that can be combined with any other embodiment described herein, the one or more sections may be provided with a curable ink, e.g. a light-curable ink. In particular, the curable ink may be an UV-curable ink. Additionally, or alternatively, the curable ink, the light-curable ink or the UV-curable ink may be a quantum dot-based ink. The ink may be printed onto the substrate, i.e. the ink may be provided into the one or more sections on the substrate. The curable ink may be photo luminescent ink, a fluorescent ink, i.e. the curable ink may emit light when excited with a light of a particular wavelength or with another stimulus providing energy to the curable ink. It is to be understood that also curable ink may be used where emittance of light can be stimulated differently, e.g. electrically and/or thermally.

[0028] According to embodiments that can be combined with any other embodiment described herein, the curable ink may include a photoinitiator. The photoinitiator may initiate a curing process of the curable ink when excited. Accordingly, the photoinitiator may induce fixation of the curable ink at the substrate. For example, when using a light-curable photo initiator, the photo initiator may initiate curing when excited with a light of a wavelength of 450 nm or less, particularly 400 nm or less, more particularly 385 nm or less. The photoinitator may be TPO, 1173 or any other suitable photoinitiator. The photoinitiator may be selected according to its absorption components leading to lower decrease of ink Photoluminescence Quantum yield (PLQY) at a specific wavelength. The term “Photloluminescence Quantum yield” may be understood as the quantity of photons emitted as a fraction of the quantity of photons absorbed. For example, suitable photoinitiators may be selected according to a higher PLQY at specific wavelengths. Suitable photoinitiators may include photoinitiators having strong absorption at lower wavelengths, e.g. wavelengths below 450 nm or less, particularly 400 nm or less, more particularly below 385 nm or less. [0029] According to embodiments that can be combined with any other embodiment described herein, the curable ink, e.g. the light-curable ink, may be excitable with a light of a wavelength at or above 400 nm to 500 nm, particularly at or above 420 nm to 500 nm, more particularly at or above 450 nm to 500 nm, even more particularly at or above 425 nm. Additionally, or alternatively, the light-curable ink may be excitable with a light of a wavelength of at least 425 nm. Accordingly, the stimulation source 130, e.g. the light source, may be configured to provide a light with a wavelength at or above the first predetermined threshold. The first predetermined threshold may be a wavelength of 385 nm or above, particularly 400 nm or above, more particularly 425 nm or above, even more particularly 450 nm or above.

[0030] Advantageously, the wavelength of the light emitted by the stimulation source or light source, i.e. the stimulation wavelength for illuminating or irradiating, i.e. stimulating, the emission of the curable ink at the substrate, prevents initiation of the curing process to allow for inspection of the substrate having curable ink provided or printed thereon before curing. Accordingly, since the curable ink is still in a “wet” condition when inspected, corrections can be made, e.g. additional ink may be provided to the substrate when less ink is detected on the substrate and/or superfluous ink can be removed before curing. Accordingly, high yields of processed substrates, i.e. substrates being provided with curable ink, can be achieved.

[0031 ] According to embodiments that can be combined with any other embodiment described herein, each section of the one or more sections may be provided with a curable ink of a different color. Particularly, the different colors may be red, green, blue and/or white. According to embodiments, each section of a cluster or subsection may include a different color. For example, of the four sections of the cluster, one section may include ink having a red color, one section may include ink having a blue color, one section may include ink having a green color and one section may include ink having a white color. Additionally, or alternatively and instead of providing a white color, the one or more sections may be left free from ink. According to embodiments, the substrate may be a display or may be used as a display in display devices.

[0032] According to embodiments that can be combined with any other embodiment described herein, the curable ink may emit light of a wavelength different from the wavelength of the light provided to the substrate by the stimulation source, i.e. the light source. In other words, the curable ink may provide a light emission upon excitation with a light of a particular wavelength provided by the light source.

[0033] According to embodiments that can be combined with any other embodiment described herein and with exemplary reference to FIG. 3, the apparatus includes a stimulation source 130. The stimulation source may be arranged at the optical inspection device 120 as exemp lardy shown in FIG. 3. Additionally, or alternatively, the stimulation source 130 may be provided adjacent to the optical inspection device. The stimulation source may be movable. The stimulation source may be movable such that stimulation, e.g. illumination, of the substrate, i.e. of the ink provided on the substrate, can be improved.

[0034] According to embodiments that can be combined with any other embodiment described herein, the apparatus includes an optical inspection device 120. The optical inspection device may include a camera 122. The optical inspection device may include a sensor or detector for sensing or detecting a light emission. The optical inspection device may include a monochrome camera and/or a color camera. The optical inspection device may be configured to detect a light emitted from the substrate, i.e. from the curable ink printed onto the substrate. For example, the optical inspection device may record or detect the light emitted from the substrate over a period of time. In other words, the optical inspection device may be configured to detect different wavelengths of light. The optical inspection device may be configured to detect or record an intensity of the light emitted from the curable ink provided on the substrate, i.e. an amount of light emitted. The intensity of light emitted may be provided as a gray-scale value. The optical inspection device may be configured to detect (a) gray-scale value(s) of the light emitted by the curable ink. Additionally, or alternatively, the optical inspection device may be configured to detect or record a color, i.e. a color intensity, of the emitted light from the curable ink provided on the substrate. For example, the optical inspection device may include a sensor for detecting or recording the emitted light. The sensor may be a CMOS-based sensor.

[0035] According to embodiments that can be combined with any other embodiment described herein, the optical inspection device may include a line scan camera. The line scan camera may be configured to detect a row of the one or more sections, i.e. a row of sections arranged in an x-direction of the coordinate system shown in FIG. 2. The line scan camera may be configured to detect 8192 pixels, i.e. sections at the same time. Additionally, or alternatively, the optical inspection device may be an area scan camera. The area scan camera may be configured to detect a row of sections arranged in an x-direction and a column of sections arranged in a y- direction of the coordinate system shown in FIG. 2. The area scan camera may be configured to detect 4096 pixels, i.e. sections arranged in the x-direction and 2160 pixels, i.e. sections arranged in the y-direction at the same time.

[0036] According to embodiments that can be combined with any other embodiment described herein, more than one optical inspection device can be provided. For example, more than 5 optical inspection devices, particularly more than 10 optical inspection devices, more particularly 12 optical inspection devices can be provided. Particularly, 12 line scan cameras can be provided. Additionally, or alternatively, more than 12 optical inspection devices, particularly more than 15 optical inspection devices, more particularly more than 20, even more particularly 24 optical inspection devices may be provided. For example, 24 area scan cameras can be provided. According to embodiments, the more than one optical inspection devices can be arranged in a staggered configuration to provide a large detection area of the optical inspection device. As used herein, a “staggered configuration” can be understood as a plurality of optical inspection devices that are arranged next to each other and that are shifted along a direction with respect to each other. For example, the term “staggered configuration” may be understood as a plurality of optical inspection devices arranged next to each other where each of the optical inspection devices is shifted or displaced with respect to the foregoing optical inspection device along the same direction by a distance that corresponds to an area of detection of the optical inspection device. The area of detection may be the dimension of a sensing device, e.g. a camera lens or sensor, for detecting the emitted light. The staggered configuration may be beneficial to account for the space occupied by each optical inspection device (e.g. the space occupied by a housing of the optical inspection device).

[0037] Advantageously, the optical inspection device or the plurality of optical inspection devices may be provided as a linearly moved optical inspection device(s). The optical inspection device may be moved along an axis perpendicular to a printing direction of the printer. The axis may correspond to a length of the substrate or a width of the substrate. For example, the length of the substrate may be 240 mm and the width may be 320 mm. Along the axis, the more than one optical inspection devices may be arranged, e.g. 12 line scan cameras or 24 area scan cameras. [0038] According to embodiments that can be combined with any other embodiment described herein, the optical inspection device may be configured to detect one or more patterns on the substrate. The one or more patterns may be fiducials or LED sites, e.g. predetermined sections of the one or more sections. The substrate may include one or more fiducials, particularly two fiducials, more particularly four fiducials for alignment of the optical inspection device and the substrate. The optical inspection device may be configured to be moved for alignment with the substrate. Additionally, or alternatively, the substrate may be moved. For example, the substrate support may be moved for alignment with the optical inspection device. The substrate support may be connected to the controller for alignment of the substrate and the optical inspection device. Additionally, or alternatively, the apparatus may include an alignment device for aligning the substrate and the optical inspection device, e.g. a positioning device for moving the optical inspection device and/or the substrate for aligning the optical inspection device and the substrate.

[0039] According to embodiments that can be combined with any other embodiment described herein, the controller 140 may be configured to calculate a position of the substrate and/or the optical inspection device from the detected one or more patterns, e.g. the fiducials, to align the optical inspection device and the substrate.

[0040] According to embodiments that can be combined with any other embodiment described herein, the optical inspection device may be configured to detect emitted polychromatic light, e.g. emitted wavelengths from the differently colored curable ink provided at the substrate. For example, the optical inspection device may detect emitted light with emission wavelengths corresponding to the emission wavelengths of a red color, green color, blue color and/or white color. Additionally, or alternatively, the optical inspection device may detect light intensities from the light emitted from the curable ink provided on the substrate. Further, the controller may be configured to calculate or determine an intensity and/or brightness of the emitted light. In other words, the controller may be configured to analyze the detected emitted light directly.

[0041 ] According to embodiments that can be combined with any other embodiment described herein, the optical inspection device 120 may further include a filter unit 124. The filter unit may include a band-pass filter. The filter unit may include one or more band-pass filters to restrict detection by the optical inspection device of the light emission emitted from the curable ink at the one or more sections to a wavelength at or above the predetermined threshold, i.e. to (a) particular wavelength(s). For example, the filter unit may include a plurality of band-pass filters. The band-pass filter(s) may be configured to let pass emitted light of a particular wavelength to the optical inspection device for detection. For example, the filter unit may include band-pass filter(s) for letting pass respective wavelengths emitted from the one or more sections filled with red curable ink, green curable ink and/or blue curable ink. Further, the band pass filter(s) may be configured to restrict wavelengths provided by the stimulation source, i.e. the light source. Accordingly, the optical inspection device may detect light emitted from the substrate, i.e. emitted from the curable ink provided on the substrate whereas detection of light emitted from the stimulation source is prevented or reduced to a minimum.

[0042] According to embodiments that can be combined with any other embodiment described herein, the filter unit, i.e. the plurality of filters, may be mechanical filters, digital filters or combinations thereof.

[0043 ] According to embodiments that can be combined with any other embodiment described herein, the controller may be configured to calculate a mean gray-scale value from the gray scale values obtained from the one or more sections detected by the optical inspection device. Additionally, or alternatively, the controller may be configured to provide a mean deviation and/or a standard deviation of the gray-scale values calculated. Further, the controller may be configured to calculate the mean deviation and/or standard deviation of the gray-scale values locally, i.e. from a specific area of the detected area or section of the one or more sections. The term “mean gray-scale value” as used herein may include the mean gray-scale value, the mean deviation and/or the standard deviation of the gray-scale value(s) detected. Particularly, the controller may be configured to calculate a mean gray-scale value, a mean deviation and/or a standard deviation from emitted light of a plurality of sections being filled with curable ink of the same color. For example, the controller may be configured to calculate a mean gray-scale value of the detected sections being filled with ink of red color, green color, blue color or white color. Accordingly, the apparatus or the controller may be configured to obtain information about a filling status of the one or more sections of the substrate from a gray-scale value, i.e. indirectly, and/or directly from a respective emitted wavelength. [0044] According to embodiments that can be combined with any other embodiment described herein, an intensity of the emitted light from the curable ink may be represented by the gray scale value. Accordingly, the gray-scale value may change depending on the amount of curable ink present at the substrate. Accordingly, the detected intensity may be used as an indicator of the filling status of the one or more sections having the curable ink. The controller may be configured to analyze or evaluate the gray-scale values and/or the obtained light emission intensities of the one or more sections. Additionally, the controller may be configured to convert the detected light emission to (a) gray-scale value(s), particularly when using a color camera.

[0045] According to embodiments that can be combined with any other embodiment described herein and with exemplary reference to FIGs. 4A to 4C, printing quality may be sufficient when the intensity of the emitted light and/or the gray-scale value or the mean gray-scale value may be in a predetermined range. In Figs. 4A to 4C, exemplarily, one or more sections including gray-scale values are shown. A light intensity of the emitted light or gray-scale value or mean gray-scale value outside of the predetermined range, e.g. a gray-scale value or mean gray-scale value being below a predetermined lower threshold or higher than a predetermined upper threshold, may be an indicator for insufficient quality of the printing result. Insufficient quality may be regarded as too much or too little ink present at the substrate. For example, if the emitted light intensity or the gray-scale value or mean gray-scale value is less than the predetermined range, an insufficient amount of curable ink may be present at the substrate, i.e. in the one or more sections. In contrast, if the emitted light intensity or the gray-scale value or mean gray scale value is higher than the predetermined range, an exceeding amount of curable ink may be present at the substrate, i.e. in the one or more sections. The same may be applicable when an intensity and/or brightness of the emitted light may be used by the controller to evaluate the filling status of the one or more sections, i.e. when the emitted light is not provided as a gray scale value. It is further to be understood that the predetermined range may vary dependent on the quality that shall be achieved, e.g. dependent on the final display quality to be achieved.

[0046] With exemplary reference to FIGs. 4A to 4C, a plurality of sections of the one or more sections 12 is shown. The plurality of sections may include curable ink of the same color or of different colors according to embodiments described herein. FIGs. 4A to 4C show subsections

14 of the substrate including different gray-scale values dependent on the amount of curable ink present in the one or more sections. For example, FIG. 4A shows a subsection 14 of the one or more sections having a gray-scale value within the predetermined range. FIGs. 4B and 4C show subsections 14 of the one or more sections having a higher and/or lower gray-scale value compared to the gray-scale value of FIG. 4 A. The gray-scale value in the depiction of FIG. 4B may include a higher light intensity and/or brightness, i.e. the detected subsection may be regarded as depicting a higher light intensity and/or brightness due to an excessive amount of curable ink present on the substrate. FIG. 4C may include a lower light intensity and/or brightness, i.e. the detected subsection may be regarded as depicting a lower light intensity and/or brightness due to an insufficient amount of curable ink present on the substrate.

[0047] According to embodiments that can be combined with any other embodiment described herein, the controller may be configured to control a position of the substrate to allow for reprinting the one or more sections if the detected emitted light intensity or the gray-scale value is below the predetermined lower threshold or above the predetermined upper threshold. The controller may control the transfer device for retransferring the substrate towards a printer as further described with respect to FIG. 6. Furthermore, and according to embodiments, the controller may be configured to calculate one or more position coordinates of the one or more sections to provide reprinting of the one or more sections where the light intensity or the gray scale value is below the predetermined lower threshold or above the predetermined upper threshold. Particularly, the controller may provide the position coordinates of the one or more sections where reprinting is required to the printer to reprint the one or more sections or the substrate.

[0048] According to embodiments that can be combined with any other embodiment described herein, the controller 140 may be connected to a computing device or any other device with computing capacity. Particularly, a cluster of computing devices, e.g. a cluster of 5 or more computing devices, particularly 10 or more computing devices, may be provided. The computing devices may be configured for data handling of data detected or provided by the optical inspection device and/or the controller. The computing device may include a CPU and a memory.

[0049] Advantageously, by using clusters of computing devices, e.g. by using 10 computers or more, real time analysis of the data detected may be provided such that a cycle time of 4 sec or less can be achieved. Accordingly, a faster performance of the system can be achieved and more substrates can be checked and/or processed. Advantageously, inspection and correction of substrates can be speeded up and facilitated.

[0050] According to embodiments that can be combined with any other embodiment described herein and with exemplary reference to FIG. 5, the stimulation source provides a stimulus at or above a first predetermined threshold. For example, the stimulation source may be a light source and the stimulus may be a wavelength at or above a first predetermined threshold. The first predetermined threshold may be a wavelength at 400 nm or above, more particularly 425 nm or above, even more particularly 450 nm or above. Accordingly, and advantageously, the curable ink, e.g. the light-curable ink, can be stimulated or illuminated such that the excitation of the curable ink may be detected while preventing the curing process of the curable ink and allowing for correction of the printing result when the curable ink is in a wet state, i.e. when the light- curable ink has not been cured yet.

[0051 ] According to embodiments that can be combined with any other embodiment described herein, the curable ink may absorb light of a particular wavelength, e.g. light with a wavelength below the predetermined threshold. Light with a wavelength below the predetermined threshold may not or slightly excite the curable ink. Energy provided by the wavelength below the predetermined threshold may lead to curing of the curable ink. Light with a wavelength at or above the predetermined threshold may prevent or reduce curing of the curable ink but may lead to excitation of light from the curable ink. The emission wavelength(s) emitted from the curable ink may be detected by the optical inspection device. For example, depending on the curable ink used, light emission, e.g. detectable photoluminescence, may occur at wavelengths in the range of 500 nm to 700 nm, particularly at wavelengths in the range of 500 nm to 620 nm. For example, maximal emission may occur with wavelengths of about 500 nm, about 520 nm, about 550 nm, about 570 nm, about 580 nm and at about 610 nm as exemplarily shown in FIG. 5. It is to be understood that also other emission wavelengths may be generated. The stimulation source, e.g. the light source, and/or the optical inspection device may be configured to provide and/or detect respective wavelengths that may not initiate curing of the curable ink but may lead to excitation and/or emission of the curable ink. Additionally, or alternatively, a period of time where the stimulus is provided by the stimulation source to the substrate, e.g. a period of time where light is provided by the light source to the substrate or curable ink, may be kept short, e.g. at a few ms or less than one second, such that the substrate can be stimulated, i.e. illuminated, without initiating the curing process.

[0052] According to embodiments that can be combined with any other embodiment described herein, light intensity, i.e. emission intensity or photoluminescence intensity may decrease with increasing wavelength. To detect decreasing intensities, the optical inspection device may include detectors, i.e. sensors having a high signal to noise ratio. For example, CMOS-based sensors may be used. Further, when plotting a calibrated light intensity, i.e. emission intensity or photoluminescence intensity against a concentration of the curable ink, an amount of ink in each of the one or more sections may be indirectly extracted.

[0053 ] According to embodiments that can be combined with any other embodiment described herein and with exemplary reference to FIG. 6, a system for processing a substrate is provided. The substrate includes one or more sections according to embodiments described herein. The system 600 includes a printer 150 for providing a curable ink to the one or more sections of the substrate and an apparatus 100 according to embodiments described herein. In particular, the apparatus includes a substrate support 110, a stimulation source 130, an optical inspection device 120 and a controller 140 according to any of the embodiments described herein. The system may include a transfer device for providing the substrate to the substrate support and/or for transferring the substrate between the printer 150 and the apparatus 100 for inspecting the substrate. Accordingly, the system and/or the apparatus may be configured to control a position of the substrate. For example, the controller 140 may be configured to control a position of the substrate to allow for reprinting the one or more sections. Accordingly, the system and/or the apparatus may allow for moving or transferring the substrate between the printer and the optical inspection device. Particularly, the controller may be configured to transfer the substrate from the optical inspection device to the printer when the light intensity detected or the gray-scale value or the mean gray-scale value calculated from the light emission detected by the optical inspection device is below or above the predetermined lower and/or upper threshold.

[0054] According to embodiments that can be combined with any other embodiment described herein, the substrate may be processed in the system, i.e. curable ink may be printed onto the substrate at and/or by the printer and the substrate may be inspected after providing the ink to the substrate. Additionally, the system may include a curing station for curing the curable ink on the substrate.

[0055] According to embodiments that can be combined with any other embodiment described herein, the printer 150 may include a printhead and a plurality of nozzles for providing curable ink to the substrate. The plurality of nozzles may be arranged in a row, e.g. the plurality of nozzles may be arranged in a row extending in an x-direction of the substrate as shown in FIG. 2 and/or the plurality of nozzles may be arranged in a row extending in the y-direction of the substrate as shown in FIG. 2. The printhead may include the nozzles. The printhead may be configured to move along the substrate in the x-direction and/or the y-direction. The printhead may be configured to provide curable ink via the plurality of nozzles to the one or more sections, i.e. the printhead may be configured to repeatedly move a distance corresponding to a width or a length of the one or more sections as described herein. The printhead may be configured to move along the plurality of rows and/or to move along the plurality of columns of the substrate. Accordingly, curable ink can be provided to each row or column of the substrate as shown with respect to FIG. 2 and/or to single sections of the one or more sections.

[0056] According to embodiments that can be combined with any other embodiment described herein, the printer 150 may be configured to align with the substrate. The printer may be configured to detect the same one or more patterns of the substrate for aligning the printer, i.e. the printhead and the substrate. Accordingly, the controller may provide information about the position of the one or more sections to the printer and the printer may be configured to particularly refill the one or more sections, the position information of which is provided from the controller.

[0057] For example, the printer may provide a curable ink of red color, green color, blue color and/or white color to the substrate, i.e. to the one or more sections of the substrate. The substrate may be transferred to the optical inspection device and may be stimulated, e.g. illuminated by the stimulation source, e.g. light source, at a wavelength at or above the first predetermined threshold. The optical inspection device may detect the light (intensity) emitted from the curable ink and may (additionally) convert the detected light emission to gray-scale values. The controller may analyze the light intensities and/or gray-scale values and may check whether the detected light emission, i.e. the intensities or calculated gray-scale values, are above or below the predetermined lower and/or upper threshold. If the light intensities or calculated gray-scale values are below the predetermined lower and/or upper threshold, the transfer device may rearrange the substrate with the printer and curable ink of red color, green color, blue color and/or white color may be reprinted on the substrate. Alternatively, instead of providing white color to the one or more sections, the one or more sections may be free from curable ink. According to embodiments, if sections of the one or more sections include ink having a wrongly printed color or if sections of the one or more sections may not be reprinted due to other deficiencies, the respective color may be provided to the sections being free from curable ink. The controller may provide respective information to the printer for correcting such deficiencies. If the light intensities or calculated gray-scale values are above the predetermined lower and/or upper threshold, superfluous ink may be removed from the substrate. Additionally, or alternatively, superfluous ink may be removed after curing.

[0058] According to embodiments that can be combined with any other embodiment described herein, the apparatus and/or the system may be configured to print one color at a time. The printing result may be checked by the optical inspection device and the controller. The printing result may be corrected if the light intensity or the gray-scale value is below or above the predetermined lower and/or upper threshold. The curable ink may be cured. Then, a differently colored curable ink may be provided and the sequence as described above may be repeated.

[0059] Advantageously, the printer may use the one or more patterns, e.g. fiducials or LED sites for alignment of the substrate and the optical inspection device for aligning the printer and the substrate to provide ink to the one or more sections where less ink is detected by the optical inspection device. Accordingly, the one or more sections where less ink is detected can be provided with additional ink and correction of ink provision can be faster and more accurate. Further advantageously, high yields of high-quality substrates can be achieved.

[0060] According to embodiments that can be combined with any other embodiment described herein and with exemplary reference to FIG. 7, a method 700 for inspecting a substrate having one or more sections in display manufacture is provided. The method includes providing (as indicated by box 755 in FIG. 7) curable ink to the one or more sections to fill the one or more sections. The one or more sections may be filled with curable ink by a printer. The one or more sections may be filled with curable ink of different colors according to any of the embodiments described herein.

[0061 ] According to embodiments that can be combined with any other embodiment described herein, the method 700 further includes aligning (as indicated by box 765 in FIG. 7) an optical inspection device and the substrate. Aligning the optical inspection device and the substrate may include pattern recognition techniques as described herein. The optical inspection device may detect one or more patterns, e.g. fiducials or LED sites, on the substrate and may be moved to align to the substrate. Additionally, or alternatively, the substrate may be moved for alignment, i.e. the substrate support may be moved to align the substrate and the optical inspection device corresponding to the recognized one or more patterns. For example, the substrate support may be in communication with the controller for providing alignment of the substrate and the optical inspection device.

[0062] According to embodiments that can be combined with any other embodiment described herein, the method 700 further includes providing (as indicated by box 775 in FIG. 7) a stimulus at or above a first predetermined threshold to the substrate. For example, light with a wavelength at or above a first predetermined threshold may be provided to the substrate, particularly to the curable ink provided at the substrate in the one or more sections. The curable ink may be a light- curable ink. The light may include a wavelength for stimulating or illuminating the curable ink, i.e. a wavelength for exciting the curable ink, but preventing initiation of a curing process of the curable ink. For example, the first predetermined threshold may be a wavelength at or above 400 nm, particularly a wavelength at or above 425 nm, more particularly a wavelength at or above 450 nm.

[0063 ] According to embodiments that can be combined with any other embodiment described herein, the method 700 further includes recording (as indicated by box 785 in FIG. 7) a light emitted from the curable ink printed on the one or more sections of the substrate with the optical inspection device. The term “recording” may be understood synonymously to the term “detecting”. The light emitted from the curable ink printed on the substrate may include a wavelength that is different from the excitation wavelength provided by the stimulation source. The optical inspection device may provide the recorded or detected light to a controller and/or computing device for computing the recorded or detected data. [0064] According to embodiments that can be combined with any other embodiment described herein, the method 700 further includes generating (as indicated by box 795 in FIG. 7) information about a filling status of the one or more sections from the light emitted from the curable ink printed on the substrate. The information may be generated by the controller. The information may be provided to the printer for reprinting the one or more sections under predetermined conditions, e.g. when the emitted light from the curable ink detected undercuts or exceeds a predetermined lower and/or upper threshold. A measure for the predetermined lower and/or upper threshold may be a gray-scale value detected by the optical inspection device or to which the detected or recorded emitted light can be converted by the optical inspection device and/or the controller.

[0065] According to embodiments that can be combined with any other embodiment described herein, the information about the filling status may include information about a filling level of the one or more sections. The filling level may also be regarded as the filling height of the one or more sections. The filing level or filling height may be determined according to embodiments described herein. For example, the light intensity or the gray-scale value to which the emitted light can be converted may be a measure of the filling level or filling height of the one or more sections.

[0066] According to embodiments that can be combined with any other embodiment described herein, recording the light emitted from the curable ink printed on the one or more sections may further include providing a gray-scale value of the light emitted from the curable ink provided on the one or more sections. The gray-scale value may be a measure of the filling status and/or filling level of the one or more sections. The gray-scale value may be detected with the optical inspection device, e.g. with a sensor of a camera. The controller may be configured to calculate a mean gray-scale value from the single gray-scale values detected from the curable ink in the one or more sections. Accordingly, for each of the one or more sections, one gray-scale value may be generated and the mean gray-scale value may be calculated from the respective plurality of gray- scale values.

[0067] According to embodiments that can be combined with any other embodiment described herein, providing curable ink may include providing one of a red, green, blue or white colored curable ink to each of the one or more sections of the substrate to provide one or more red, green, blue or white colored sections. Furthermore, generating information about a filling status of the one or more sections may include extracting a mean gray-scale value for a group of the one or more green colored sections, the one or more red colored sections, the one or more blue colored sections or the one or more white colored sections. Additionally, the extracted mean gray-scale value may be compared with a lower and/or upper predetermined threshold.

[0068] Additionally, or alternatively, the mean gray-scale value may be extracted from a plurality of subsections of the substrate, i.e. from a group of four sections where one section may include ink having a red color, one section may include ink having a green color, one section may include ink having a blue color and one section may include ink having a white color, respectively.

[0069] Accordingly, by analyzing the emitted light intensity, the gray-scale values and/or mean gray-scale values, the filling status and/or filling level of the one or more sections, particularly of a plurality of sections, may be obtained to receive information about the printing quality of the substrate and/or printer. [0070] According to embodiments that can be combined with any other embodiment described herein, the method may further include refilling the one or more sections with curable ink when the light intensity or the extracted mean gray-scale value is above and/or below the predetermined lower and/or upper threshold. Particularly, refilling of the one or more sections may be provided when the intensity or the mean gray-scale value is below or above the predetermined lower and/or upper threshold. The term “refilling” may be understood synonymously to the term ’’reprinting” as used herein. Reprinting or refilling of the one or more sections may include retransferring the substrate to the printer and providing additional ink to the one or more sections.

[0071 ] According to embodiments that can be combined with any other embodiment described herein, providing curable ink may include providing light-curable ink, quantum dot-based curable ink and/or UV-curable ink. The ink may further include a photoinitiator to allow for curing of the curable ink.

[0072] According to embodiments that can be combined with any other embodiment described herein, the method may further include curing the curable ink provided to the one or more sections. Curing may be provided by exposing the curable ink to a light having a wavelength that can initiate polymerization of the photo initiator of the curable ink, e.g. light of a wavelength being absorbed by the curable ink.

[0073] In view of the above, it is to be understood that compared to the state of the art, embodiments of the present disclosure beneficially provide for an apparatus for inspecting a substrate having curable ink printed in one or more sections, a system for processing a substrate and a method for inspecting a substrate having one or more sections which are improved with respect to curing prevention, illumination of the substrate and quality control of the substrate in the field of high quality display manufacturing. Further, embodiments described herein beneficially provide for the use of wet ink inspection apparatuses compared to conventional inspection apparatuses.

[0074] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. An apparatus (100) for inspecting a substrate (10) in display manufacture, the substrate having one or more sections having curable ink provided therein, the apparatus comprising: a substrate support (110); a stimulation source (130) for providing a stimulus at or above a first predetermined threshold to the substrate; an optical inspection device (120) for detecting a light emission emitted from the curable ink at the one or more sections; and a controller (140) for providing information about a filling status of the one or more sections calculated from the light emission detected by the optical inspection device.

2. The apparatus according to claim 1, wherein the stimulation source (130) comprises a light source, and wherein the light source is configured to provide a wavelength at or above the first predetermined threshold to the substrate.

3. The apparatus according to any of claims 1 or 2, wherein the optical inspection device comprises a monochrome camera or a color camera.

4. The apparatus according to any of claims 1 to 3, wherein the optical inspection device comprises a filter unit (124).

5. The apparatus according to claim 4, wherein the filter unit (124) comprises one or more band-pass filters to restrict detection by the optical inspection device of the light emission emitted from the curable ink at the one or more sections to a wavelength at or above the first predetermined threshold.

6. The apparatus according to any of claims 2 to 5, wherein the first predetermined threshold is a wavelength of 385 nm or above, particularly 400 nm or above, more particularly 425 nm or above, even more particularly 450 nm or above.

7. The apparatus according to any of claims 1 to 6, wherein the optical inspection device is configured to detect one or more patterns on the substrate, and wherein the controller is configured to calculate a position of the substrate and the optical inspection device from the detected one or more patterns to align the optical inspection device and the substrate.

8. The apparatus according to any of claims 1 to 7, wherein the controller is configured to calculate one or more position coordinates of the one or more sections to provide reprinting of the one or more sections when the light emission is above or below a predetermined lower and/or upper threshold.

9. The apparatus according to any of claims 1 to 8, wherein the controller is configured to calculate a mean gray-scale value from the light emission detected from the one or more sections.

10. The apparatus according to any of claims 1 to 9, wherein the apparatus further comprises an alignment device for aligning the substrate and the optical inspection device.

11. A system (600) for processing a substrate, the substrate having one or more sections, the system comprising: a printer (150) for providing a curable ink to the one or more sections of the substrate; and an apparatus (100) according to any of claims 1 to 10.

12. A method (700) for inspecting a substrate having one or more sections in display manufacture, the method comprising: providing curable ink to the one or more sections to fill the one or more sections; aligning an optical inspection device and the substrate; providing a stimulus at or above a first predetermined threshold; recording a light emitted from the curable ink printed on the one or more sections of the substrate with the optical inspection device; and generating information about a filling status of the one or more sections from the light emitted from the curable ink printed on the substrate.

13. The method (700) according to claim 12, wherein the information about the filling status comprises information about a filling level of the one or more sections.

14. The method (700) according to claims 12 or 13, wherein the stimulus is light and the first predetermined threshold is a wavelength at or above 400 nm, particularly a wavelength at or above 425 nm, more particularly a wavelength at or above 450 nm, even more particularly a wavelength at or above 500 nm.

15. The method (700) according to claims 12 to 14, wherein recording the light emitted from the curable ink printed on the one or more sections further comprises providing a gray-scale value of the light emitted from the curable ink printed on the one or more sections.

16. The method (700) according to claim 15, wherein providing curable ink comprises providing one of a green, red, blue or white colored curable ink to each of the one or more sections of the substrate to provide one or more green, red, blue or white colored sections and wherein generating information about a filling status of the one or more sections comprises: extracting a mean gray-scale value for a group of the one or more green colored sections, the one or more red colored sections, the one or more blue colored sections or the one or more white colored sections; and comparing the extracted mean gray-scale value with a predetermined lower and/or upper threshold.

17. The method (700) according to claim 16, wherein the method further comprises refilling the one or more sections with curable ink when the extracted mean gray-scale value is above and/or below the predetermined upper and/or lower threshold.

18. The method (700) according to any of claims 12 to 17, wherein providing curable ink comprises providing light-curable ink, quantum dot-based curable ink and/or UV-curable ink.

19. The method (700) according to any of claims 12 to 18, wherein the method further comprises curing the curable ink provided to the one or more sections.