TWI870647B - Apparatus and method for inspecting a substrate in display manufacture and system for processing a substrate - Google Patents

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 substrates in display manufacturing and system for processing substrates

The present disclosure relates to the field of display manufacturing, and more particularly to the field of providing substrates used in display applications. More particularly, the present disclosure relates to an apparatus and method for inspecting a substrate having a curable ink printed thereon.

In display manufacturing, several technologies are known to provide displays with improved resolution and contrast characteristics, and many approaches have been developed. While liquid crystal displays (LCDs) use the light-modulating properties of liquid crystals to affect light provided by a backlight or reflector to produce color or monochrome images, organic light-emitting diode (OLED) display technology provides organic materials that directly emit visible light in response to electrical power.

As is well known, OLED displays have beneficial effects compared to LCDs, such as providing thinner and lighter displays, achieving deeper black levels and higher contrast, and being flexible and transparent, thus allowing OLED displays to be used in a variety of applications such as monitors, TVs, and smart phones.

OLED substrates are typically produced by coating the substrate with organic materials that provide the primary colors of red, blue, and green to produce pixels on the substrate. For example, the coating process can provide pixels of different colors on the substrate based on the evaporation of organic materials (such as host materials and dopant materials) deposited on the substrate.

Compared to OLED technology, micro light-emitting diodes (LEDs) provide tiny pixels on a substrate. Micro LEDs are made of inorganic materials, such as indium gallium nitride (InGaN) provided as a semiconductor array. Micro LEDs are able to emit light in response to electrical power. In terms of display manufacturing, micro LED technology is beneficial compared to OLED technology in terms of the lifetime, brightness and contrast of the resulting display. To date, micro LED arrays suitable for display manufacturing have been expensive and inefficient to manufacture. In addition, there are different methods for providing colored pixels to micro LED-based substrates for displays. One method is to provide colored inks to the substrate by a printing process to produce pixels of different colors.

In view of the foregoing, it would be beneficial to provide improved apparatus, systems, and methods for display manufacturing, particularly for manufacturing including the printing of color pixels.

According to the present disclosure, an apparatus for inspecting a substrate in display manufacturing is provided. The substrate has one or more portions in which a curable ink is disposed, and the apparatus includes a substrate support, a stimulus source for providing a stimulus at or above a first predetermined threshold to the substrate, an optical inspection device for detecting light emission emitted from the curable ink at the one or more portions, and a controller for providing information about a fill state of the one or more portions calculated from the light emission detected by the optical inspection device.

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

According to one aspect, a method for inspecting a substrate having one or more portions in display manufacturing is provided. The method includes the steps of providing a curable ink to the one or more portions to fill the one or more portions; aligning an optical inspection device with the substrate; providing a stimulus at or above a first predetermined threshold; using the optical inspection device to record light emitted from the curable ink printed on the one or more portions of the substrate; and generating information about the filling status of the one or more portions from the light emitted from the curable ink printed on the substrate.

Embodiments also relate to apparatus for performing the disclosed methods and include apparatus components for performing each of the described method aspects. These method aspects may be performed by hardware components, computers programmed by appropriate software, any combination of the two, or in any other manner. In addition, embodiments according to the present disclosure also relate to methods for operating the described apparatus. Embodiments include method aspects for performing each function of the apparatus.

Reference will now be made in detail to various embodiments of the present disclosure, one or more of which are shown in the figures. In the following figure descriptions, the same element symbols refer to the same elements. Generally, only the differences with respect to the various embodiments are described. Each example is provided for the purpose of explaining the present invention and is not meant to limit the present disclosure. In addition, features shown or described as part of one embodiment may be used on other embodiments or used in combination with other embodiments to produce yet another embodiment. The present disclosure is intended to include such modifications and variations.

In the following figure descriptions, the same element symbols refer to the same or similar parts. Generally, only the differences between the various embodiments are described. Unless otherwise specified, the description of a part or aspect in one embodiment is also applicable to the corresponding part or aspect in another embodiment.

In display manufacturing, color pixels can be produced on a substrate by printing corresponding inks on the substrate. For example, the latest technology can use curable inks printed on substrates to provide high density pixels on the substrate to provide high resolution displays. The substrate is provided with ink, and the ink is cured to be fixed on the substrate.

The ink needs to be printed with high precision in order to obtain a high yield and a high quality substrate. In particular, in the field of micro-LED based displays, where the individual pixels comprise sizes in the micrometer range, printing precision is beneficial. This may include not only the location where the ink is provided, e.g. where it is printed on the substrate, but also the amount of ink provided. Therefore, the method for providing the ink to the substrate, e.g. the printing method, may be subject to quality inspection, since the amount of ink provided and the printing precision may vary over time and may have a negative impact on the printing result.

In view of the above, it would be beneficial to provide apparatus, methods and systems for inspecting substrates bearing (eg, printed with) curable inks to ensure high quality and high yield in display manufacturing.

According to an embodiment that can be combined with any other embodiment described herein, and with exemplary reference to FIG. 1, an apparatus for inspecting a substrate 10 in display manufacturing is provided. The substrate includes one or more portions in which a curable ink is provided. The apparatus includes a substrate support 110. In addition, the apparatus includes a stimulus source 130 for providing a stimulus at or above a first predetermined threshold to the substrate. In addition, the apparatus includes an optical inspection device 120 for detecting light emission emitted from the curable ink at one or more portions, and a controller 140 for providing information about the filling state of the one or more portions calculated based on the light emission detected by the optical inspection device.

According to an embodiment that can be combined with any other embodiment described herein, a substrate can be provided at the substrate support 110. The substrate is further described with reference to FIG. 2. The substrate can be a glass substrate. Additionally or alternatively, the substrate can further include a polymer material. The substrate can be made of a polymer material. The substrate can include and/or be made of a flexible polymer material. The substrate can be automatically provided to the substrate support (e.g., by a conveyor, etc.). The substrate support can include a non-reflective property, for example, the substrate support can be transparent, or can include a dark color, so that the substrate support can prevent interference with the stimulus provided to the substrate by the stimulus source, such as light provided by the light source.

According to an embodiment that can be combined with any other embodiment described herein, the stimulation source 130 can stimulate light emission of the curable ink. The stimulation source can be used to irradiate the substrate. The stimulation source 130 can be used to provide energy to the curable ink provided on the substrate. The stimulation of the curable ink can be provided by light, thermal shock and/or electrical shock. For example, the stimulation source 130 can be used to provide light equal to or greater than a predetermined wavelength to the substrate. In particular, the stimulation source can be used to provide light at a wavelength that can excite the curable ink printed on the substrate. Therefore, the stimulation source 130 can be a light source. The light source can be a wide spectrum light source. In addition or alternatively, the light source can include an LED to provide light of a specific wavelength. The curable ink provided on the substrate can emit light of a wavelength different from the wavelength provided to the substrate from the stimulation source 130 (i.e., from the light source). More specifically, the light source can provide light with a wavelength that excites the curable ink while preventing the curing reaction of the curable ink from being triggered. The curable ink may be a photocurable ink.

According to an embodiment that can be combined with any other embodiment described herein, the inspection device 120 can inspect light emitted from the substrate. The optical inspection device can be used to detect light intensity, such as grayscale values, and/or color intensity or brightness emitted by the substrate (i.e., by the curable ink provided at the substrate). The optical inspection device can be movably arranged on the equipment. The inspection device 120 can be attached to a holding device 126. The holding device 126 can be moved to inspect various areas of the substrate. For example, the holding device can be movable so that the optical inspection device can inspect multiple columns and/or multiple rows of the substrate. In addition or alternatively, the substrate support can be movable to arrange the substrate and the inspection device for appropriate inspection.

According to an embodiment that can be combined with any other embodiment described herein, the device may include a controller 140 for providing information about the filling state of one or more parts calculated based on the light emission detected by the optical inspection device. In particular, the controller can be used to obtain information about the filling state from the light intensity and/or brightness of the light emitted by the curable ink. In addition or alternatively, the controller can be used to obtain information about the filling state from the grayscale value of the light emitted by the curable ink provided at one or more parts. The term "grayscale value" used in this article can be understood as a measurement of the brightness and/or intensity of the light detected from a part of one or more parts. A part of one or more parts of the substrate can be regarded as a pixel. For example, a grayscale value can be provided for each of the one or more detected parts, that is, a grayscale value can be provided for each pixel on the substrate. Additionally or alternatively, the controller may be used to obtain information about the fill status from the color intensity and/or color brightness of the light emitted by the curable ink.

The term "filling state" as used herein may be understood as information about the presence of ink on the substrate (i.e. in one or more portions), or information about the amount of ink present on the substrate (i.e. in one or more portions). Thus, the term "filling state" may include qualitative and/or quantitative information about the curable ink.

According to an embodiment that can be combined with any other embodiment described herein, and with exemplary reference to FIG. 2, the substrate 10 includes one or more parts 12. One or more parts can be arranged in a matrix. One or more parts can provide a grid. One or more parts can be square. For example, one or more parts can have an extension in the x-direction and an extension in the y-direction of the Cartesian coordinate system (as shown in the example in FIG. 2). The extensions in the x-direction and the y-direction may have the same magnitude, that is, one or more parts may include widths and lengths of the same size. For example, the extensions in the x-direction and the y-direction, that is, the width and length of a part, may include a size in the range of 10 μm to 50 μm, specifically a size in the range of 20 to 40 μm, and more specifically a size of 30 μm. For example, each of the one or more parts can have a length of 30 μm and a width of 30 μm. One or more parts may each include a depth in the paper plane direction of FIG. 2. The depth may define the fill height of the one or more parts. The depth of the one or more parts may be in the range of 0.1 mm to 1 mm, specifically 0.3 mm to 0.8 mm, more specifically 0.5 mm.

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

According to an embodiment that can be combined with any other embodiment described herein, the substrate may in particular include a plurality of parts, for example, the substrate may include more than 10M (million) parts, in particular more than 20M parts, more particularly 30M or more parts. According to an embodiment, the total size of the substrate may be 240mm x 320mm. Each of the one or more parts may represent a pixel on the substrate.

According to an embodiment that can be combined with any other embodiment described herein, one or more parts can be grouped into a sub-portion 14. The sub-portion 14 can include four of the one or more parts shown in dashed lines in FIG. 2. The cluster or sub-portion can include four of the one or more parts arranged in a 2x2 matrix or square. Thus, each cluster or sub-portion can include four parts, two of which are arranged above or below the other two parts of the same cluster or sub-portion.

According to an embodiment that can be combined with any other embodiment described herein, one or more parts can be provided with a curable ink, such as a light curable ink. In particular, the curable ink can be a UV curable ink. Additionally or alternatively, the curable ink, light curable ink or UV curable ink can be an ink based on quantum dots. The ink can be printed onto a substrate, i.e. the ink can be provided in one or more parts on a substrate. The curable ink can be a photoluminescent ink, a fluorescent ink, i.e. the curable ink can emit light when excited with light of a specific wavelength or with another stimulus that provides energy to the curable ink. It should be understood that curable inks can also be used, wherein the light emission can be stimulated differently, such as electrical stimulation and/or thermal stimulation.

According to an embodiment 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. Therefore, the photoinitiator may induce fixation of the curable ink on the substrate. For example, when a photocurable photoinitiator is used, the photoinitiator may initiate curing when excited with light having a wavelength of 450 nm or less, specifically 400 nm or less, and more specifically 385 nm or less. The photoinitiator may be TPO, 1173, or any other suitable photoinitiator. The photoinitiator may be selected according to its absorbing component, thereby reducing the photoluminescence quantum yield (PLQY) of the ink at a specific wavelength. The term "photoluminescence quantum yield" may be understood as the fraction of the number of photons emitted to the number of photons absorbed. For example, a suitable photoinitiator can be selected based on a higher PLQY at a specific wavelength. Suitable photoinitiators may include photoinitiators with strong absorption at lower wavelengths, such as wavelengths below 450 nm or less, specifically 400 nm or less, and more specifically below 385 nm or less.

According to an embodiment that can be combined with any other embodiment described herein, the curable ink (e.g., photocurable ink) can be excited by light having a wavelength of 400 nm to 500 nm or more, specifically 420 nm to 500 nm or more, more specifically 450 nm to 500 nm or more, more specifically 425 nm or more. Additionally or alternatively, the photocurable ink can be excited by light having a wavelength of at least 425 nm. Thus, the stimulus source 130, such as a light source, can be used to provide light having a wavelength at or above a first predetermined threshold. The first predetermined threshold can be a wavelength of 385 nm or more, specifically 400 nm or more, more specifically 425 nm or more, even more specifically 450 nm or more.

Advantageously, the wavelength of light emitted by the stimulus source or light source, i.e. the stimulus wavelength for illumination or irradiation, i.e. the emission of the curable ink on the substrate, prevents initiation of the curing process so as to inspect the substrate on which the curable ink is provided or printed before curing. Thus, since the curable ink is still in a "wet" state when inspecting, corrections can be made, e.g. additional ink can be provided to the substrate when less ink is detected on the substrate and/or excess ink can be removed before curing. Thus, a high yield of processed substrates, i.e. substrates provided with curable ink, can be achieved.

According to an embodiment that can be combined with any other embodiment described herein, each of the one or more parts may have a different color of curable ink. In particular, the different colors may be red, green, blue and/or white. According to an embodiment, each part of a cluster or sub-part may include a different color. For example, out of four parts of a cluster, one part may include an ink with red, one part may include an ink with blue, one part may include an ink with green, and one part may include an ink with white. Additionally or alternatively, instead of providing white, one or more parts may be free of ink. According to an embodiment, the substrate may be a display, or may be used as a display in a display device.

According to an embodiment that can be combined with any other embodiment described herein, the curable ink can emit light having a wavelength different from the wavelength of light provided to the substrate by the stimulation source (i.e., the light source). In other words, the curable ink can provide light emission when excited by light of a specific wavelength provided by the light source.

According to an embodiment that can be combined with any other embodiment described herein, and exemplarily with reference to FIG. 3 , the apparatus includes a stimulus source 130. The stimulus source can be arranged at the optical inspection device 120, as exemplarily shown in FIG. 3 . Additionally or alternatively, the stimulus source 130 can be arranged near the optical inspection device. The stimulus source can be mobile. The stimulus source can be movable so that the stimulus (e.g., illumination) to the substrate can be improved, for example, the stimulus to the ink provided on the substrate.

According to an embodiment 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 light emission. The optical inspection device may include a monochrome camera and/or a color camera. The optical inspection device can be used to detect light emitted from a substrate, i.e., light emitted from a curable ink printed on the substrate. For example, the optical inspection device can record or detect light emitted from the substrate over a period of time. In other words, the optical inspection device can be used to detect light of different wavelengths. The optical inspection device can be used to detect or record the intensity of light emitted from the curable ink provided on the substrate, i.e., the amount of light emitted. The intensity of the emitted light can be provided as a grayscale value. The optical inspection device may be used to detect (a) grayscale value of light emitted by the curable ink. Additionally or alternatively, the optical inspection device may be used to detect or record the color, i.e., color intensity, of the light emitted 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.

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

According to an embodiment that can be combined with any other embodiment described herein, more than one optical inspection device may be provided. For example, more than 5 optical inspection devices may be provided, specifically more than 10 optical inspection devices, and more specifically 12 optical inspection devices may be provided. In particular, 12 line scan cameras may be provided. Additionally or alternatively, more than 12 optical inspection devices may be provided, specifically more than 15 optical inspection devices, more specifically more than 20 optical inspection devices, and even more specifically 24 optical inspection devices. For example, 24 area scan cameras may be provided. According to an embodiment, more than one optical inspection device may be arranged in a staggered configuration to provide a large inspection area of the optical inspection device. As used herein, a "staggered configuration" may be understood as a plurality of optical inspection devices arranged adjacent to one another and moving in directions relative to one another. For example, the term "staggered configuration" may be understood as a plurality of optical inspection devices arranged adjacent to one another, wherein each optical inspection device is moved or displaced a distance in the same direction relative to the preceding optical inspection device, and the distance corresponds to the detection area of the optical inspection device. The detection area may be the size of a sensing device (e.g., a camera lens or a sensor) used to detect emitted light. A staggered configuration may help to illustrate the space occupied by each optical inspection device (e.g., the space occupied by the housing of the optical inspection device).

Advantageously, the optical inspection device or the plurality of optical inspection devices can be provided as linearly movable optical inspection devices. The optical inspection device can be movable along an axis perpendicular to the printing direction of the printer. The axis can correspond to the length or width of the substrate. For example, the length of the substrate can be 240 mm and the width can be 320 mm. Along the axis, more than one optical inspection device can be arranged, for example 12 line scan cameras or 24 area scan cameras.

According to an embodiment that can be combined with any other embodiment described herein, an optical inspection device can be used to detect one or more patterns on a substrate. The one or more patterns can be reference points or LED positions, such as predetermined portions of one or more portions. The substrate can include one or more reference points, particularly two reference points, and more particularly four reference points, for aligning the optical inspection device with the substrate. The optical inspection device can be used to move to align with the substrate. Additionally or alternatively, the substrate can be moved. For example, the substrate support can be moved to align with the optical inspection device. The substrate support can be connected to a controller for aligning the substrate with the optical inspection device. Additionally or alternatively, the apparatus can include an alignment device for aligning the substrate with the optical inspection device, for example, a positioning device for moving the optical inspection device and/or the substrate to align the optical inspection device with the substrate.

According to an embodiment that can be combined with any other embodiment described herein, the controller 140 can be used to calculate the position of the substrate and/or the optical inspection device based on the detected one or more patterns (e.g., reference points) to align the optical inspection device with the substrate.

According to an embodiment that can be combined with any other embodiment described herein, the optical inspection device can be used to detect emitted polychromatic light, for example, to detect emission wavelengths from different colors of curable ink provided on the substrate. For example, the optical inspection device can detect emitted light having an emission wavelength corresponding to red, green, blue and/or white emission wavelengths. Additionally or alternatively, the optical inspection device can detect the light intensity of the light emitted from the curable ink provided on the substrate. Furthermore, the controller can be used to calculate or determine the intensity and/or brightness of the emitted light. In other words, the controller can be used to directly analyze the detected emitted light.

According to an embodiment 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 bandpass filter. The filter unit may include one or more bandpass filters to limit the detection of light emission emitted by the curable ink at one or more parts of the optical inspection device to wavelengths at or above a predetermined threshold, i.e., (a) specific wavelengths. For example, the filter unit may include a plurality of bandpass filters. The bandpass filters may be used to allow emission light of a specific wavelength to pass through the optical inspection device for detection. For example, the filter unit may include a bandpass filter for passing each wavelength emitted from one or more parts filled with red curable ink, green curable ink and/or blue curable ink. In addition, the bandpass filter can be used to limit the wavelength provided by the stimulus source (i.e., the light source). Thus, the optical inspection device can detect light emitted from the substrate, i.e., light emitted from the curable ink provided on the substrate, while the detection of light emitted from the stimulus source is blocked or reduced to a minimum.

According to an embodiment, which can be combined with any other embodiment described herein, the filter unit (ie, a plurality of filters) may be a mechanical filter, a digital filter, or a combination thereof.

According to an embodiment that can be combined with any other embodiment described herein, the controller can be used to calculate an average gray value based on gray values obtained from one or more parts detected by the optical inspection device. In addition or alternatively, the controller can be used to provide an average deviation and/or standard deviation of the calculated gray values. In addition, the controller can be used to calculate the average deviation and/or standard deviation of the gray values locally, that is, from a specific area of the inspection area or a portion of one or more parts. The term "average gray value" used herein may include the average gray value, average deviation and/or standard deviation of the detected gray values. In particular, the controller can be used to calculate the average gray value, average deviation and/or standard deviation from the emitted light of multiple parts filled with the same color of curable ink. For example, the controller can be used to calculate the average gray value of the inspected part, and the inspection part is filled with red, green, blue or white ink. Thus, an apparatus or a controller may be used to obtain information about the filling state of one or more portions of the substrate from the grey values (ie indirectly) and/or directly from the corresponding emission wavelengths.

According to an embodiment, which may be combined with any other embodiment described herein, the intensity of the emitted light of the curable ink may be represented by a grayscale value. Thus, the grayscale value may vary depending on the amount of curable ink present on the substrate. Thus, the detected intensity may be used as an indicator of the filling state of one or more portions with curable ink. The controller may be used to analyze or evaluate the grayscale value of one or more portions and/or the obtained luminescence intensity. Furthermore, the controller may be used to convert the detected light emission into (a) grayscale values, in particular when using a color camera.

According to an embodiment that can be combined with any other embodiment described herein, and with reference to FIGS. 4A to 4C as examples, the print quality may be sufficient when the intensity and/or the grayscale value or the average grayscale value of the emitted light may be within a predetermined range. In FIGS. 4A to 4C, one or more sections including grayscale values are shown as examples. The light intensity of the emitted light or the grayscale value or the average grayscale value outside the predetermined range, such as a grayscale value or the average grayscale value below a predetermined lower threshold or above a predetermined upper threshold, may be an indicator of insufficient quality of the print result. Insufficient quality may be considered as too much or too little ink being present on the substrate. For example, if the intensity of the emitted light or the grayscale value or the average grayscale value is less than the predetermined range, an insufficient amount of curable ink may be present on the substrate, i.e. in one or more sections. Conversely, if the emitted light intensity or grayscale value or average grayscale value is above the predetermined range, there may be an excess of curable ink on the substrate (i.e. in one or more portions). The same applies when the controller can use the intensity and/or brightness of the emitted light to assess the filling state of one or more portions, i.e. when the emitted light is not provided as a grayscale value. It will further be appreciated that the predetermined range may vary depending on the quality to be achieved, for example, depending on the final display quality to be achieved.

With reference to Figures 4A to 4C, a plurality of portions of one or more portions 12 are shown. According to embodiments described herein, the plurality of portions may include curable inks of the same color or different colors. Figures 4A to 4C show sub-portions 14 of a substrate including different grayscale values depending on the amount of curable ink present in the one or more portions. For example, Figure 4A shows a sub-portion 14 of one or more portions having grayscale values within a predetermined range. Figures 4B to 4C show sub-portions 14 of one or more portions having higher and/or lower grayscale values compared to the grayscale values of Figure 4A. The grayscale values in the depiction of Figure 4B may include higher light intensity and/or brightness, i.e., the detected sub-portion may be considered to depict a higher light intensity and/or brightness due to the presence of excess curable ink on the substrate. Figure 4C may include lower light intensity and/or brightness, i.e., the detected sub-portion may be considered to depict lower light intensity and/or brightness due to an insufficient amount of curable ink present on the substrate.

According to an embodiment that can be combined with any other embodiment described herein, the controller can be used to control the position of the substrate to allow reprinting of one or more parts when the detected emitted light intensity or grayscale value is lower than a predetermined lower threshold or higher than a predetermined upper threshold. The controller can control the conveying device to retransmit the substrate to the printer, as further described with respect to FIG. 6. In addition, according to an embodiment, the controller can be used to calculate one or more position coordinates of one or more parts so as to provide reprinting of one or more parts when the light intensity or grayscale value is lower than a predetermined lower threshold or higher than a predetermined upper threshold. In particular, the controller can provide the printer with the position coordinates of the one or more parts that need to be reprinted to reprint the one or more parts or substrates.

According to an embodiment that can be combined with any other embodiment described herein, the controller 140 can be connected to a computing device or any other device having computing capabilities. In particular, a cluster of computing devices can be provided, for example, a cluster consisting of 5 or more computing devices, in particular 10 or more computing devices. The computing device can be used to perform data processing on data detected or provided by the optical inspection device and/or the controller. The computing device can include a CPU and a memory.

Advantageously, by using a cluster of computing devices, for example by using 10 or more computers, the detected data can be analyzed in real time, so that a cycle time of 4 seconds or less can be achieved. Thus, faster performance of the system can be achieved, and more substrates can be inspected and/or processed. Advantageously, inspection and correction of substrates can be accelerated and facilitated.

According to an embodiment that can be combined with any other embodiment described herein, and exemplarily with reference to FIG. 5 , the stimulus source provides a stimulus at or above a first predetermined threshold. For example, the stimulus source can be a light source, and the stimulus can be a wavelength at or above the first predetermined threshold. The first predetermined threshold can be a wavelength of 400 nm or higher, more specifically 425 nm or higher, even more specifically 450 nm or higher. Thus, advantageously, a curable ink (e.g., a photocurable ink) can be stimulated or illuminated so that the excitation of the curable ink can be detected while preventing the curing process of the curable ink and allowing the print result to be corrected when the curable ink is in a wet state, i.e., when the photocurable ink has not yet cured.

According to an embodiment that may be combined with any other embodiment described herein, the curable ink may absorb light of a specific wavelength, such as light having a wavelength below a predetermined threshold. Light having a wavelength below the predetermined threshold may not or slightly excite the curable ink. The energy provided by the wavelength below the predetermined threshold may cause curing of the curable ink. Light having a wavelength at or above the predetermined threshold may prevent or reduce curing of the curable ink, but may cause excitation of light from the curable ink. The emission wavelength emitted from the curable ink may be detected by an optical inspection device. For example, depending on the curable ink used, light emission (e.g., detectable photoluminescence) may occur at a wavelength in the range of 500 nm to 700 nm, specifically at a wavelength in the range of 500 nm to 620 nm. For example, the maximum emission may occur at wavelengths of about 500 nm, about 520 nm, about 550 nm, about 570 nm, about 580 nm, and about 610 nm, as shown in the example of FIG. 5. It should be understood that other emission wavelengths may also be generated. The stimulus source (e.g., light source) and/or the optical inspection device may be used to provide and/or detect corresponding wavelengths that may not induce curing of the curable ink but may cause the curable ink to be excited and/or emitted. Additionally or alternatively, the time period during which the stimulus source provides stimulus to the substrate, such as the time period during which the light source provides light to the substrate or the curable ink, may be kept short, such as a few milliseconds or less than 1 second, so that the substrate can be stimulated (i.e., illuminated) without initiating a curing process.

According to an embodiment that can be combined with any other embodiment described herein, the light intensity, i.e., the emission intensity or the photoluminescence intensity, can decrease as the wavelength increases. In order to detect the reduced intensity, the optical inspection device can include a detector, i.e., a sensor with a high signal-to-noise ratio. For example, a CMOS-based sensor can be used. In addition, when the calibration light intensity, i.e., the emission intensity or the photoluminescence intensity, is plotted against the curable ink concentration, the amount of ink in each of the one or more portions can be indirectly extracted.

According to an embodiment 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 parts according to the embodiments described herein. The system 600 includes a printer 150 for providing a curable ink to one or more parts of the substrate and an apparatus 100 according to the embodiments described herein. In particular, the apparatus includes a substrate support 110, a stimulus source 130, an optical inspection device 120, and a controller 140 according to any embodiment described herein. The system may include a conveying device for providing the substrate to the substrate support and/or for conveying the substrate between the printer 150 and the apparatus 100 for inspecting the substrate. Thus, the system and/or the apparatus can be used to control the position of the substrate. For example, the controller 140 can be used to control the position of the substrate to allow reprinting of one or more parts. Thus, the system and/or apparatus may allow a substrate to be moved or transferred between a printer and an optical inspection device. In particular, the controller may be configured to transfer the substrate from the optical inspection device to the printer when the detected light intensity or grayscale value or the average grayscale value calculated based on the light emission detected by the optical inspection device is below or above a predetermined lower and/or upper threshold.

According to an embodiment that can be combined with any other embodiment described herein, a substrate can be processed in a system, i.e. a curable ink can be printed onto the substrate at and/or by a printer, and the substrate can be inspected after the ink is provided to the substrate. Furthermore, the system can include a curing station for curing the curable ink on the substrate.

According to an embodiment that can be combined with any other embodiment described herein, the printer 150 may include a print head and a plurality of nozzles for providing curable ink to a substrate. The plurality of nozzles may be arranged in a row, for example, the plurality of nozzles may be arranged in a row extending in the 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 print head may include nozzles. The print head may be movable along the substrate in the x-direction and/or the y-direction. The print head may be configured to provide curable ink to one or more portions via the plurality of nozzles, i.e., the print head may be configured to repeatedly move a distance corresponding to the width or length of one or more portions described herein. The print head may be configured to move along the plurality of rows of the substrate and/or along the plurality of rows. Thus, as shown in FIG. 2 , the curable ink may be provided to each column or row and/or a single portion of one or more portions of the substrate.

According to an embodiment that can be combined with any other embodiment described herein, the printer 150 can be used to align with the substrate. The printer can be used to detect the same one or more patterns of the substrate for aligning the printer (i.e., the print head) with the substrate. Thus, the controller can provide information about the position of one or more parts to the printer, and the printer can be used to specifically refill one or more parts whose position information is provided from the controller.

For example, a printer may provide a substrate, i.e. one or more portions of the substrate, with a curable ink of red, green, blue and/or white. The substrate may be conveyed to an optical inspection device and may be stimulated, e.g. illuminated by a stimulus source (e.g. a light source) at a wavelength at or above a first predetermined threshold. The optical inspection device may detect light (intensity) emitted from the curable ink and may (in addition) convert the detected light emission into a grayscale value. The controller may analyze the light intensity and/or grayscale value and may check whether the detected light emission, i.e. the intensity or the calculated grayscale value, is above or below a predetermined lower and/or upper threshold. If the light intensity or the calculated grayscale value is below the predetermined lower and/or upper threshold, the conveying device may reposition the substrate with the printer and may reprint the curable ink of red, green, blue and/or white on the substrate. Alternatively, instead of providing white to one or more portions, one or more portions may be free of curable ink. According to an embodiment, if portions of the one or more portions include ink having an incorrectly printed color, or if portions of the one or more portions may not be reprinted due to other defects, the portions without curable ink may be provided with the corresponding color. The controller may provide corresponding information to the printer to correct such defects. If the light intensity or the calculated grayscale value is above a predetermined lower and/or upper threshold, excess ink may be removed from the substrate. Additionally or alternatively, excess ink may be removed after curing.

According to an embodiment, which can be combined with any other embodiment described herein, the apparatus and/or system can be used to print one color at a time. The print result can be checked by an optical inspection device and a controller. If the light intensity or grayscale value is below or above a predetermined lower and/or upper threshold, the print result can be corrected. The curable ink can be cured. Subsequently, a different color of curable ink can be provided, and the above sequence can be repeated.

Advantageously, the printer may align the substrate with the optical inspection device using one or more patterns, such as reference dots or LED spots, for aligning the printer with the substrate so as to provide ink to one or more portions where the optical inspection device detects less ink. Thus, additional ink may be provided to the one or more portions where less ink is detected, and correction of ink supply may be faster and more accurate. More advantageously, a high yield of high-quality substrates may be achieved.

According to an embodiment 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 portions in display manufacturing is provided. The method includes providing (as shown in block 755 in FIG. 7 ) a curable ink to fill the one or more portions. The one or more portions can be filled with the curable ink by a printer. According to any embodiment described herein, the one or more portions can be filled with curable inks of different colors.

According to an embodiment that may be combined with any other embodiment described herein, method 700 further includes the step of aligning (as shown in box 765 in Figure 7) the optical inspection device with the substrate. The step of aligning the optical inspection device with the substrate may include pattern recognition techniques as described herein. The optical inspection device can detect one or more patterns on the substrate, such as fiducial points or LED locations, and can be moved to align with the substrate. Additionally or alternatively, the substrate can be moved for alignment, that is, the substrate support can be moved to align the substrate with the optical inspection device corresponding to the one or more identified patterns. For example, the substrate support can communicate with a controller to provide alignment of the substrate with the optical inspection device.

According to an embodiment that can be combined with any other embodiment described herein, method 700 further includes providing (as shown in block 775 in FIG. 7 ) a stimulus at or above a first predetermined threshold to the substrate. For example, light having a wavelength at or above the first predetermined threshold may be provided to the substrate, in particular to a curable ink provided in one or more portions at the substrate. The curable ink may be a photocurable ink. The light may include a wavelength for stimulating or illuminating the curable ink, i.e., a wavelength for stimulating the curable ink but preventing the initiation of a curing process of the curable ink. For example, the first predetermined threshold may be a wavelength of 400 nm or more, in particular a wavelength of 425 nm or more, and more particularly a wavelength of 450 nm or more.

According to an embodiment that can be combined with any other embodiment described herein, method 700 further includes recording (as shown in block 785 in FIG. 7 ) light emitted from the curable ink printed on one or more portions of the substrate with an optical inspection device. The term "recording" may be understood as a synonym for the term "detecting". The light emitted from the curable ink printed on the substrate may include a wavelength different from the excitation wavelength provided by the stimulus source. The optical inspection device may provide the recorded or detected light to a controller and/or a computing device to calculate the recorded or detected data.

According to an embodiment that can be combined with any other embodiment described herein, method 700 further includes (as shown in block 795 in FIG. 7 ) generating information about the fill status of one or more parts based on the light emitted from the curable ink printed on the substrate. The information can be generated by the controller. The information can be provided to the printer to reprint the one or more parts under predetermined conditions (e.g., when the detected light emitted by the curable ink is below or exceeds a predetermined lower and/or upper threshold). The predetermined lower and/or upper threshold can be measured as a grayscale value detected by the optical inspection device, or the detected or recorded emitted light can be converted into a grayscale value by the optical inspection device and/or the controller.

According to an embodiment that can be combined with any other embodiment described herein, the information about the filling state can include information about the filling degree of one or more parts. The filling degree can also be regarded as the filling height of one or more parts. The filling degree or filling height can be determined according to the embodiments described herein. For example, the light intensity or grayscale value that the emitted light can be converted into can be a measurement of the filling degree or filling height of one or more parts.

According to an embodiment which can be combined with any other embodiment described herein, recording light emitted by the curable ink printed on one or more parts can further include the step of providing a gray value of the light emitted by the curable ink provided on the one or more parts. The gray value can be a measure of the filling state and/or filling degree of the one or more parts. The gray value can be detected by an optical inspection device, such as a sensor of a camera. The controller can be used to calculate an average gray value based on the single gray values detected from the curable ink in the one or more parts. Therefore, for each of the one or more parts, a gray value can be generated, and the average gray value can be calculated from the corresponding plurality of gray values.

According to an embodiment that can be combined with any other embodiment described herein, the step of providing a curable ink may include providing one of red, green, blue or white curable inks to each of the one or more portions of the substrate to provide one or more red, green, blue or white portions. Furthermore, generating information about the filling state of the one or more portions may include the step of extracting an average gray value of a group of one or more green portions, one or more red portions, one or more blue portions or one or more white portions. Furthermore, the extracted average gray value may be compared with a lower and/or higher predetermined threshold value.

Additionally or alternatively, the average grey value may be extracted from a plurality of sub-portions of the substrate, i.e. from a set of four portions, wherein, respectively, one portion may include ink having a red colour, one portion may include ink having a green colour, one portion may include ink having a blue colour, and one portion may include ink having a white colour.

Therefore, by analyzing the emitted light intensity, gray value and/or average gray value, the filling state and/or filling degree of one or more parts, in particular a plurality of parts, can be obtained to receive information about the printing quality of the substrate and/or the printer.

According to an embodiment, which can be combined with any other embodiment described herein, the method may further comprise the step of refilling one or more portions with curable ink when the light intensity or the extracted average grey value is above and/or below a predetermined lower and/or upper threshold. In particular, refilling of one or more portions may be provided when the intensity or the average grey value is below or above a predetermined lower and/or upper threshold. The term "refilling" may be understood as a synonym for the term "reprinting" as used herein. Reprinting or refilling of one or more portions may comprise retransmitting the substrate to the printer and providing additional ink to the one or more portions.

According to an embodiment that can be combined with any other embodiment described herein, the step of providing a curable ink can include providing a photocurable ink, a quantum dot-based curable ink and/or a UV curable ink. The ink can further include a photoinitiator to allow curing of the curable ink.

According to an embodiment that can be combined with any other embodiment described herein, the method can further include a step of curing the curable ink provided to the one or more parts. Curing can be provided by exposing the curable ink to light having a wavelength that can initiate polymerization of a photoinitiator of the curable ink (e.g., light of a wavelength that the curable ink absorbs).

In view of the above, it should be appreciated that, compared to the prior art, embodiments of the present invention advantageously provide an apparatus for inspecting a substrate having a curable ink printed thereon in one or more sections, a system for processing a substrate, and a method for inspecting a substrate having one or more sections that are improved in terms of curing prevention, illumination of the substrate, and quality control of the substrate in the field of high quality display manufacturing. Furthermore, embodiments described herein advantageously provide for the use of a wet ink inspection apparatus as compared to known inspection apparatuses.

Although the foregoing relates to embodiments of the present disclosure, other and further embodiments of the present invention may be devised without departing from the basic scope of the invention, and the scope thereof is determined by the following claims.

10: substrate 12: section 14: subsection 16: column 18: row 110: substrate support 120: optical inspection device 122: camera 124: filter unit 126: holding device 130: stimulus source 140: controller 150: printer 600: system 700: method 755: box 765: box 775: box 785: box 795: box x: direction y: direction

In order to understand the above features of the present disclosure in detail, a more specific description of the present disclosure briefly summarized above can be obtained by referring to the embodiments. The following figures are related to the embodiments of the present disclosure:

FIG. 1 shows a schematic front view of an apparatus according to an embodiment described herein;

FIG. 2 shows a schematic top view of a substrate according to an embodiment of the present invention;

FIG3 shows a schematic front view of an apparatus according to an embodiment described herein;

Figures 4A to 4C illustrate examples of sub-portions according to embodiments described herein;

FIG5 shows a wavelength diagram according to an embodiment of the present invention;

FIG6 shows a schematic front view of a system according to an embodiment described herein; and

Figure 7 shows a flow chart of a method according to an embodiment described herein.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

10: Substrate

110: Baseboard support

120: Optical inspection device

126: Holding device

130: Stimulus

140: Controller

Claims (18)

An apparatus (100) for inspecting a substrate (10) in display manufacturing, the substrate having one or more portions of a curable ink provided therein before the curable ink is cured, wherein the curable ink is a UV curable ink, wherein the curable ink includes a photoinitiator for initiating a curing process of the curable ink, the apparatus comprising: a substrate support (110); a stimulus source (130) for providing a stimulus at or above a first predetermined threshold to the substrate, wherein the first predetermined threshold The threshold is a wavelength selected from the group consisting of 385 nm or more, 400 nm or more, 425 nm or more, and 450 nm or more, wherein the wavelength does not trigger a curing reaction of the UV curable ink; an optical inspection device (120) for detecting a light emission emitted from the curable ink at the one or more parts; and a controller (140) for providing information about a filling state of the one or more parts calculated based on the light emission detected by the optical inspection device. The apparatus as claimed in claim 1, wherein the stimulus source (130) comprises a light source, and wherein the light source is used to provide a wavelength at or above the first predetermined threshold to the substrate. The apparatus as described in claim 1, wherein the optical inspection device comprises a monochrome camera or a color camera. An apparatus as claimed in claim 1, wherein the optical inspection device includes a filter unit (124). The apparatus of claim 4, wherein the filter unit (124) comprises one or more bandpass filters for limiting the detection of the light emission emitted by the optical inspection device at one or more portions of the curable ink to a wavelength at or above the first predetermined threshold. The apparatus as described in claim 1, wherein the optical inspection device is used to detect one or more patterns on the substrate, and wherein the controller is used to calculate a position of the substrate and the optical inspection device based on the detected one or more patterns to align the optical inspection device with the substrate. The apparatus of claim 1, wherein the controller is configured to calculate one or more position coordinates of the one or more portions to provide for reprinting of the one or more portions when the light emission is above or below a threshold selected from a group consisting of a predetermined lower threshold and a predetermined upper threshold. An apparatus as claimed in any one of claims 1 to 7, wherein the controller is used to calculate an average grayscale value based on the light emission detected from the one or more parts. An apparatus as described in any one of claims 1 to 7, wherein the apparatus further comprises an alignment device for aligning the substrate with the optical inspection device. A system (600) for processing a substrate having one or more portions, the system comprising: a printer (150) for providing a curable ink to the one or more portions of the substrate; and an apparatus (100) as described in any one of claims 1 to 7. A method (700) for inspecting a substrate having one or more portions in display manufacturing, the method comprising the steps of: providing a curable ink to the one or more portions to fill the one or more portions, wherein the curable ink is a UV curable ink, wherein the curable ink includes a photoinitiator for initiating a curing process of the curable ink; aligning an optical inspection device with the substrate; providing a stimulus at or above a first predetermined threshold, wherein the first predetermined threshold The threshold is a wavelength selected from the group consisting of 385 nm or more, 400 nm or more, 425 nm or more, and 450 nm or more, wherein the wavelength does not trigger a curing reaction of the UV curable ink; recording a light emitted from the curable ink printed on the one or more parts of the substrate with the optical inspection device; and generating information about a filling state of the one or more parts based on the light emitted by the curable ink printed on the substrate. The method (700) of claim 11, wherein the information about the filling state of the one or more parts includes information about a filling degree of the one or more parts. A method (700) as claimed in claim 11 or 12, wherein the stimulus is light and the first predetermined threshold is a wavelength of 500 nm or more. The method (700) as described in claim 13, wherein the step of recording the light emitted by the curable ink printed on the one or more parts further includes the step of providing a grayscale value of the light emitted by the curable ink printed on the one or more parts. The method (700) as claimed in claim 14, wherein the step of providing a curable ink comprises the following steps: providing one of green, red, blue or white curable inks to each of the one or more portions of the substrate to provide one or more green, red, blue or white portions, and wherein the step of generating information about a filling state of the one or more portions comprises the following steps: extracting an average gray value of a group of the one or more green portions, the one or more red portions, the one or more blue portions or the one or more white portions; and comparing the extracted average gray value with one selected from a group consisting of a predetermined lower limit and a predetermined upper limit threshold. The method (700) as claimed in claim 15, wherein the method further comprises the step of refilling the one or more portions with curable ink when the extracted average grayscale value is higher or lower than a value selected from a group consisting of the predetermined upper limit and the predetermined lower limit threshold. The method (700) as described in claim 11, wherein the step of providing a curable ink comprises the following steps: providing one of the group consisting of a photocurable ink, a quantum dot-based curable ink and a UV curable ink. The method (700) of claim 11, further comprising the step of curing the curable ink provided to the one or more parts.