High-speed measurement of droplet parameters in industrial printing systems

Abstract

To provide a droplet measurement system (DMS) used in an industrial printer used to fabricate, e.g., a thin film layer of a flat panel electronic device.SOLUTION: A clear tape serves as a printing substrate to receive droplets from hundreds of nozzles simultaneously, while an optics system photographs the deposited droplets through the tape. This permits immediate image analysis of deposited droplets, for parameters such as the per-nozzle volume, the landing position and other characteristics, without having to substantially reposition the DMS or printhead. The tape can then be advanced and used for new measurement. By providing such a high degree of concurrency, the described system permits rapid measurement and update of droplet parameters for printers that use hundreds or thousands of nozzles, to provide a real-time understanding of per-nozzle expected droplet parameters, in a manner that can be taken into account in print planning.SELECTED DRAWING: Figure 2

Description

[Background technology]

[0001] (Cross-reference to related applications) This application claims priority to U.S. Provisional Patent Application No. 62 / 044,958, “Fast Measurement Of Droplet Parameters In Industrial Printing System,” filed on September 2, 2014, on behalf of the first inventor, Christopher R. Hauf. This application also claims priority to U.S. Patent Application No. 14 / 340403, “Techniques for Print Ink Droplet Measurement and Control to Deposit Fluids within Precise Tolerances,” filed on July 24, 2014, on behalf of the first inventor, Nahid Harjee, and is a continuation of that application. Next, U.S. Patent Application No. 14 / 340403 claims priority to U.S. Provisional Patent Application No. 61 / 950,820, “Techniques For Print Ink Droplet Volume Measurement And Control Over Deposited Fluids Within Precise Tolerances,” filed on March 10, 2014, on behalf of the first inventor, Nahid Harjee. Next, U.S. Patent Application No. 14 / 340403 claims priority to PCT Patent Application No. PCT / US2014 / 035193, “Techniques for Print Ink Droplet Measurement and Control to Deposited Fluids within Precise Tolerances,” filed on April 23, 2014, on behalf of the first inventor, Nahid Harjee, and the first invention filed on January 23, 2014. The applicant claims priority over both the U.S. General Patent Application No. 14 / 162525, “Techniques for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances,” which was filed on behalf of the original inventor Nahid Harjee, and the applicant itself is a continuation of those applications. Next, the U.S. General Patent Application No. 14 / 162525 claims priority over Taiwan Patent Application No. 102148330, “Techniques for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances,” which was filed on December 26, 2013, on behalf of the original inventor Nahid Harjee, and PCT Patent Application No. PCT / US2013 / 077720, “Techniques for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances,” which was filed on December 24, 2013, on behalf of the original inventor Nahid Harjee.PCT patent application PCT / US2013 / 077720 is a compilation of two provisional patent applications: U.S. Provisional Patent Application No. 61 / 746,545 for "Smart Mixing," filed on December 27, 2012, on behalf of the first inventor Conor Francis Madigan; U.S. Provisional Patent Application No. 61 / 822855 for "Systems and Methods Providing Uniform Printing of OLED Panels," filed on May 13, 2013, on behalf of the first inventor Nahid Harjee; U.S. Provisional Patent Application No. 61 / 842351 for "Systems and Methods Providing Uniform Printing of OLED Panels," filed on July 2, 2013, on behalf of the first inventor Nahid Harjee; and "Systems and Methods Providing Uniform Printing of OLED Panels," filed on July 23, 2013, on behalf of the first inventor Nahid Harjee. Priority is claimed to the following U.S. Provisional Patent Application No. 61 / 857298, “Panels”, U.S. Provisional Patent Application No. 61 / 898769, “Systems and Methods Providing Uniform Printing of OLED Panels”, filed on November 1, 2013, on behalf of the first inventor, Nahid Harjee, and U.S. Provisional Patent Application No. 61 / 920,715, “Techniques for Print Ink Volume Control To Deposit Fluids Within Precise Tolerances”, filed on December 24, 2013, on behalf of the first inventor, Nahid Harjee.PCT Patent Application No. PCT / US2014 / 035193 further claims the benefit of U.S. Provisional Patent Application No. 61 / 816696, filed on April 26, 2013, in the name of the first inventor Alexander Sou-Kang Ko, and U.S. Provisional Patent Application No. 61 / 866031, filed on August 14, 2013, in the name of the first inventor Alexander Sou-Kang Ko, both entitled "OLED Printing Systems and Methods Using Laser Light Scattering for Measuring Ink Drop Size, Velocity and Trajectory". Priority is claimed with respect to each of the above-mentioned applications, and each of the above-mentioned patent applications is incorporated herein by reference.

[0002] (Background) Industrial manufacturing processes are increasingly relying on printing systems to process layers of products. These printing systems deposit fluids, which are then cured or hardened to form a permanent layer of a particular product. These manufacturing processes are particularly useful for processing one or more microelectronic products using arrays of quasi-electronic structures. For example, such printing processes are increasingly being used to manufacture thin-film electronic displays and solar panels for a wide variety of applications. The described printing systems are typically characterized by the use of thousands of printing nozzles on one or more printheads, designed with the ability to position individual, substantially uniform-sized droplets with near-micron resolution, in addition to the type of fluid used ("ink"). This precision control over the volume and position of deposited droplets helps to facilitate high quality in the final product, as well as in products with high resolution and small footprint, and reduced manufacturing costs. For example, in one application, namely the manufacture of organic light-emitting diode (OLED) displays, the ability to precisely deposit ink helps to produce smaller, thinner, and more robust displays at lower costs. While the term "ink" is used to refer to the deposition fluid, it should be noted that the deposition fluid is typically colorless and deposited as a structure that will "build" the thickness of the permanent layer on the device; that is, the color of the fluid itself is typically irrelevant in the sense that it would be important for inks used in conventional graphics printing applications.

[0003] Unsurprisingly, in these applications, quality control depends on the uniformity of deposited ink droplets with respect to size (droplet volume) and precise position, or at least an understanding of variations in such characteristics is crucial for producing permanent layers that consistently meet the desired quality standards for layer alignment accuracy and / or layer homogeneity. In industrial printing systems, it should be noted that droplet uniformity for any given nozzle can also potentially change over time, whether due to statistical variations, changes in nozzle life, clogging, variations in ink viscosity or composition, temperature, or other factors. [Overview of the project] [Problems that the invention aims to solve]

[0004] What is needed is a droplet measurement system, ideally adapted for use in situ with printing systems used by industrial processing equipment, for use in connection with industrial printing processes. Ideally, such a droplet measurement system would provide near-rapid measurement of one or more droplet parameters, be easy to maintain, and provide inputs that can be used to adjust printing to enable precise quality control for use in industrial product processing processes. This invention addresses these needs and provides further relevant advantages. [Means for solving the problem]

[0005] In one embodiment, the droplet measurement system receives ink droplets from various nozzles of one or more printheads and then uses optical analysis to measure the values ​​of parameters associated with the various droplets and / or the various printhead nozzles that produced these droplets. More specifically, as discussed below, some embodiments use a deposition tape in the printer maintenance bay for test printing of ink from various nozzles simultaneously. The tape can be any medium capable of receiving ink droplets, advantageously, but in the notable embodiments discussed below, it comprises a transparent film that closely resembles photographic paper and is specially treated to fix the wet ink droplets. Also in one embodiment, the system is applied in industrial processing equipment where the droplets to be deposited themselves are transparent or translucent (e.g., representing panel devices such as displays or solar panels, or materials that will be deposited and cured to form an encapsulation layer of photogenerating elements in such devices). This transparency allows for the image capture of a group of one or more droplets for a set of multiple nozzles, and in an optional embodiment, droplet deposition can be distinguished from both the film and the imaged nozzle location (behind the film) to provide extremely fast measurement of droplet position offset (relative to the ideal droplet position) and / or volume and / or timing errors associated with droplet deposition.

[0006] In one embodiment, for the purpose of performing measurements, one or more printheads are stationed in a maintenance station, for example, while a substrate is loaded or unloaded in the printer (and thus while the printer / processing equipment is otherwise employed). When the printheads are stationed, the droplet measurement system is engaged to bring the deposition medium (e.g., a transparent film) close to one or more printheads in a manner that is aligned to the specific positions of one or more printheads. Then, nozzles from one or more of the printheads (e.g., a window or subarray with a subset of all nozzles) are fired, one or a series of droplets (e.g., 2, 5, 10, etc.) so that the droplets accrete onto the medium near the expected positions on a given nozzle. During or after this time, the film is imaged effectively through the transparent film from the side of the film opposite the printheads. In other words, the film is precisely positioned at a typical deposition distance (e.g., <1.0 mm) relative to the nozzle being measured, and the measurement is performed simultaneously (or immediately afterward) on multiple nozzles by firing these nozzles at the same time, and then capturing an image through the opposite side of the film, and the resulting captured image is then processed to derive droplet parameter values.

[0007] Note some of the advantages of the features of the various embodiments described so far. First, the described optical processing of deposited droplets through a transparent film is particularly useful for very large printheads having hundreds or thousands of nozzles, i.e., the optical processing can be performed immediately without the need to further move the printhead, droplet measurement system, or other components. Second, the droplet measurement system can be configured to measure droplets from many nozzles simultaneously, for example, by ejecting droplets from hundreds of nozzles and measuring them simultaneously. Compared to a system that optically images one at a time, e.g., an individual droplet in flight, this type of simultaneous parallelism can greatly help to facilitate the measurement of droplets across thousands of printhead nozzles (as used, for example, in some industrial processing applications). With respect to systems that rely on dynamically updated measurement of droplet parameters, this type of simultaneous parallelism can be important because it does not require a significant interruption of printing time or manufacturing throughput in order to combine droplets in a manner that mitigates variability or addresses variability in generating a precise target volume. Regarding a droplet measurement system that articulates one or more stationary printheads within a service station, this provides easy and precise access to any of thousands of print nozzles, which can be used in several industrial manufacturing processes. Furthermore, the deposition tape or its treatment can be specifically adapted to the chemical properties of the particular ink under test (i.e., to allow its properties to be more easily or precisely confirmed by optical means). As should be obvious, the described technique provides enhanced precision and lower costs in manufacturing products, particularly price-oriented consumer products such as flat-panel high-definition televisions ("HDTVs").

[0008] With respect to at least one design discussed below, the droplet measurement system mounts a transparent film using a roll-to-roll mechanism that allows the film to advance as tape across the imaging area, enabling intermittent replacement of the tape roll used for measurement. In addition, the droplet measurement system may also, advantageously, use a vacuum system to tightly adhere that portion of the tape that is deposited in a flat, precise positional relationship that mimics an online deposition surface. The droplet measurement system may also optionally include a curing station to cure / dry the ink so that excess ink does not diffuse to any other part of the system after measurement. It should be noted that this is not necessary in some embodiments, and for example, the film may also be selected or treated to have properties such that ink droplets are immediately fixed once deposited. Also, as described, the droplet measurement system may optionally be mounted on a three-dimensional movable mount. That is, it can be mounted to engage with a stationary printhead from below along the vertical ("z") axis, and to move as desired along the x (and optionally y) axis to reach different nozzles and different printheads. This allows a "large" printhead assembly (e.g., with thousands of nozzles) to be stationary while the droplet measurement system is articulated below the print surface (e.g., in a maintenance bay) and used to measure parameters of different groups of nozzles. One deposition process to consider is to advance a roll of tape so that a window of unused tape is adjacent to a selected printhead, and these printheads are then controlled to release a predetermined amount of ink into their nozzles to be fixed on the tape, while simultaneously, a coaxial camera and image sensor from below (e.g., in the housing or chassis of the droplet measurement system) images all deposited droplets in parallel (by image capture through the opposite portion of the tape, so that the film and droplet measurement system do not need to be moved or repositioned, typically for analysis). If desired, the camera (or image acquisition optics) can be made movable relative to the droplet measurement system to provide, for example, scanning activity over the range of the nozzle, focusing, or other desired benefits.

[0009] The output of the image processing system then provides droplet parameter data useful for verifying nozzle legitimacy or planning alternative printing. After any desired measurement iteration, the tape and droplet measurement system are advanced to their respective positions, the used tape is cured and / or wound up, and this process is then repeated immediately or later, as needed. In designs where the tape cannot be reused once printed, rolls of used tape (or tape cartridges with reels and capstans for new and used tape) can be collected or replaced periodically on a modular basis. In one conceivable application where the processing mechanism is used continuously (for example, to print layers for an OLED television screen, or otherwise to process layers for one or more flat panel devices), the printhead is stationary when the previous substrate is loaded or unloaded, subjected to the droplet measurement described, and as soon as the next new substrate is ready, the measurement progress is memorized, the printhead is returned to the active printing task, and it should be noted that when this next substrate is finished, the printhead is returned to the maintenance station again (while the new substrate is being loaded) so that the system can resume the measurement that was previously stopped. In this way, iterative measurements can be used as a rolling criterion to construct a statistical distribution of each printing nozzle or combination of nozzle waveforms through many measurements (as described, for example, in the aforementioned patent application incorporated by reference), using a moving measurement window that advances cyclically through all sets of printing nozzles so that measurement data is collected for each nozzle and measurement data is continuously updated.

[0010] It should be noted that all process steps described above (and below) can be implemented in several ways. For example, in one embodiment, these steps are performed by one or more computers or other types of machines (such as a printer or one or more manufacturing devices), either by dedicated hardware or by general-purpose hardware configured to operate as a dedicated machine. For example, in one considered design, one or more of the tasks may be performed by one or more such machines, operating under the control of instructions stored on a non-transient machine-readable medium, e.g., firmware or software. Such instructions are written or designed in a manner having certain structure (architectural features) such that, when finally executed, one or more general-purpose machines (e.g., processors, computers, or other machines) behave as general-purpose machines having a structure that necessarily performs the tasks described on the input operands in order to take action or otherwise produce output. "Non-transient machine-readable medium" is not limited to how the data on the medium is stored, but the instructions may be later machine-readable. Machine-readable media means any tangible (i.e., physical) storage medium that can be read by a machine, including random access memory, hard disk memory, optical memory, floppy disks or CDs, server storage devices, volatile memory, and other tangible mechanisms. Machine-readable media may be in standalone form (e.g., program disks) or may be embodied as part of larger mechanisms, such as laptop computers, portable devices, servers, networks, printers, or other sets of one or more devices. Instructions may be implemented in different forms, for example, as metadata that is effective in invoking a certain action when invoked, as Java® code or scripts, as code written in a specific programming language (e.g., as C++ code), as a processor-specific instruction set, or in some other form. Instructions may also be executed by the same processor or different processors, depending on the embodiment. Throughout this disclosure, various processes will be described, any of which may be implemented as instructions stored on non-transient machine-readable media, and any of which may be used to process products using "3D printing" or other printing processes. Depending on the product design, such products may be processed to be in a sealable form, or as a preliminary step for other printing, curing, manufacturing, or other processing steps that will ultimately produce a finished product for sale, distribution, export, or import. Depending on the implementation, instructions on a non-transient machine-readable medium may be executed by a single computer, or in other cases, they may be stored and / or executed on a distributed basis, for example, using one or more servers, web clients, or application-specific devices. Each function described may be implemented as part of a composite program, stored together on a single medium representation (e.g., a single floppy disk) or on multiple separate storage devices, or as a standalone module.

[0011] Furthermore, it should be noted that "transparent" as used in relation to film or tape is a relative term, meaning it refers to the ability to capture an image of droplets deposited on the first side of the tape through a second side of the tape. This does not, strictly speaking, require the tape to be colorless or, in that respect, transparent to visible light. In one embodiment, the tape is colorless and highly transparent to visible light, and visible light is used to capture an image of these droplets, on which liquid is deposited from each nozzle, such that the droplets from each nozzle are aligned on the first side of the tape (i.e., at their respective positions correlated with each nozzle). In another embodiment, the tape has some color, optimized for the ink, for example, to enhance the image-capturing properties of the specific ink. In yet another embodiment, radiation other than visible light is used to capture the droplet properties.

[0012] Various other features will be obvious to those skilled in the art from the description herein. Having thus introduced the features of several embodiments, this disclosure now moves on to provide additional details relating to optional embodiments. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a flowchart illustrating the technique for measuring droplet parameters. [Figure 2] Figure 2 is a close-up perspective view of the droplet measurement system. [Figure 3] Figure 3 is a cross-sectional view of the droplet measurement system. [Figure 4A] Figure 4A is another perspective view of the droplet measurement system. [Figure 4B] Figure 4B is a perspective view of the droplet measurement system from Figure 4A, taken from the viewpoint indicated by arrow BB in Figure 4A. [Figure 5A] Figure 5A is a flowchart associated with an image processing technique used in one embodiment. [Figure 5B]FIG. 5B is a captured image of a sample representing droplets deposited on a medium after conversion to grayscale. [Figure 5C] FIG. 5C is the captured image of FIG. 5B after filtering (e.g., gradient processing). [Figure 6A] FIG. 6A is an illustrative schematic showing the manufacture of a layer associated with product processing, and the techniques disclosed herein can be implemented in any of the depicted layers, though not limited thereto. [Figure 6B] FIG. 6B shows a processing apparatus in a plan view. [Figure 7A] FIG. 7A is an illustrative representation regarding the use of a droplet measurement system. [Figure 7B] FIG. 7B is a flowchart regarding droplet measurement. [Figure 7C] FIG. 7C is a flowchart regarding droplet verification. [Figure 8A] FIG. 8A is a cross-sectional view of elements of an industrial printer inside a printing chamber. [Figure 8B] FIG. 8B is a cross-sectional view of the industrial printer of FIG. 7A taken along line B-B of FIG. 8A. [Figure 9] FIG. 9 is a schematic showing a comparison of measured droplet positions with respect to their respective expected positions. [Figure 10] FIG. 10 is a flowchart regarding droplet volume calculation.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] The subject matter defined by the enumerated claims should be read carefully in conjunction with the accompanying drawings and may be better understood by referring to the embodiments for carrying out the invention described below. This description of one or more specific embodiments, which are set forth below to enable the construction and use of various implementations of the techniques described by the claims, is not intended to limit the enumerated claims but to illustrate their uses. Without limiting the foregoing, this disclosure provides several different embodiments of droplet measurement systems that measure or image deposited droplets on a medium and use image processing to identify parameter values ​​of various nozzles of a print head used in industrial processing. Various techniques can be embodied as droplet measurement systems, as printers or processing apparatuses, as software for performing the techniques described, in the form of a computer, printer or other device running such software, or in the form of electronic or other devices (e.g., flat panel devices or other consumer end products) processed as a result of these techniques. Although specific embodiments are presented, the principles described herein may also be applied to other methods, devices, and systems.

[0015] (Detailed explanation) FIG. 1 shows a flow diagram 101 that illustrates some of the techniques described herein. As shown above, it is desired to simultaneously measure the values of droplet parameters of droplets generated by a number of nozzles. To do this as rapidly as possible, the embodiments disclosed herein rely on image capture of a deposition surface that receives such droplets (i.e., high-speed capture of droplets collectively representing a plurality of nozzles), and image processing that calculates the values of one or more desired parameters for the plurality of nozzles from this image capture. As described by reference numeral 103, one or more printheads under analysis fire a range or array of nozzles, thereby depositing one or more droplets each. To provide an example, a hypothetical printhead could have 2,000 nozzles, and these nozzles could be measured in groups of 100 nozzles at a time. For each measurement iteration, the printhead and / or droplet measurement system is aligned, the window or group of 100 nozzles to be measured is identified, and a controlled ink volume is fired substantially simultaneously. In one embodiment, the deposition can be a single droplet per nozzle, and in other embodiments, a number of droplets, e.g., 2, 5, 10, 12, 20, or some other number of droplets can be controllably ejected from each nozzle. Note that in certain contemplated designs (e.g., for OLED applications), the droplet size typically is very small, with droplet diameters in the tens of microns or smaller, deposited with near-micron accuracy, and can include picoliter ("pL") sized droplets.

[0016] As described in the aforementioned patent application incorporated by reference, depending on the application, it may be desirable to measure the position of the deposited droplet, the droplet velocity, the droplet volume, the nozzle bend, or one or more other parameters of each nozzle. Briefly, in one embodiment, it is important to anticipate the droplet quality from each nozzle for each deposited droplet. That is, if one nozzle is out of position relative to the other (nozzle bend), or if it produces an abnormal droplet trajectory or inaccurate droplet volume, this can lead to non-uniformity of the deposited film. Such non-uniformity can lead to quality defects in precision products, such as display devices and equivalents. Understanding such abnormalities on a nozzle-by-nozzle basis enables the following:

[0017] (a) Nozzle Qualification / Disqualification - Nozzles that are not operational or otherwise have abnormal characteristics may be identified and cannot be used for printing, and the software may plan the print in a manner in which different nozzles are used to deposit droplets in the desired area.

[0018] (b) Firing time mitigation - Position defects in the scanning direction can potentially be compensated for by varying the nozzle drive pulse with respect to timing or voltage so that the nozzle fires earlier or later, or discharges the liquid at a faster or slower rate. In addition, it is also possible to use alternative drive pulses as disclosed in the aforementioned patent application incorporated by reference.

[0019] (c) Planned droplet combinations - The detected differences between nozzles are acceptable and can be intentionally used when calculating droplet combinations based on their respective expected values ​​to achieve precise results within specific tolerances. For example, if one nozzle is measured and determined to produce an expected 9.89 picoliters (pL) droplet, and a second nozzle is measured and determined to produce an expected 10.11 pL droplet, and it is desired to produce a total volume of 20.00 pL of ink at a specific target location, these two nozzles can be specifically identified, and printing can be planned to deposit this specific droplet combination. Note that the obtainable results will differ from systems that simply average the differences regardless of the specific filling volume or filling tolerance (e.g., target volume ±0.50%).

[0020] (d) Pre-selection of drive waveforms - As described in the aforementioned patent application incorporated by reference, it is possible to pre-select programmable drive waveforms for each nozzle to be stored and used during printing (e.g., selection of 16 pre-selected drive waveforms), each waveform being selected to achieve specific deposition characteristics with precise expected results.

[0021] It should be noted that droplet parameters can potentially fluctuate daily, even between depositions, depending on factors such as ink quality, temperature, nozzle life (e.g., clogging), and other factors. Therefore, in some implementations, it may be desirable to remeasure these values ​​from time to time to ensure accurate printing. It should also be noted that each deposited droplet can differ slightly, even from a single nozzle. Therefore, in one embodiment, each nozzle (or nozzle-waveform combination or pair) is measured not just once, but multiple times, to produce a set of measurements from which averages or other statistical parameters (e.g., diffusion measure) can be calculated to provide high confidence in the expected values ​​of the droplet parameters. For example, "24" droplets from each nozzle-waveform pair may be measured to produce average volume, velocity, bending (at a position perpendicular to the scanning direction), etc. (and thus their expected values). The number n (n=24) helps reduce uncertainty due to measurement error or statistical variation. A given population can be updated on a rolling basis (e.g., all measurements are stored, and the six most recent measurements replace the six oldest measurements for each nozzle every two hours) or on an immediate basis (e.g., all nozzles are immediately remeasured upon power-on). There are many variations that will come to mind for those skilled in the art; for example, nozzles can be measured to determine expected values, and nozzles can be deemed unsuitable for use if the actual measured (expected) value is out of band within ±5% of the ideal value, and many permutations and variations are clearly possible.

[0022] However, as should be obvious, in a printing system using thousands of nozzles (for example, tens of thousands or more, each perhaps with multiple available "pre-selected" drive waveforms), measuring the expected droplet parameters of each nozzle can potentially be quite time-consuming. In an industrial manufacturing environment, this is typically unacceptable, meaning that for it to be commercially viable, manufacturing throughput and costs must be such that products can be produced at an acceptable consumer price, which typically means that the printing process must produce as many products as possible with the best possible accuracy (and the least product waste) and the least amount of downtime. The techniques disclosed herein are much faster and therefore enable feasible measurements.

[0023] Referring to Figure 1, in this sense, the droplet measurement technique presented by this disclosure also captures droplets from many nozzles at once, by the number 105. That is, in contrast to systems that image droplets in flight "one by one," the embodiments presented by this disclosure rely on synchronous operation to measure as many nozzles as possible simultaneously. Thus, image capture can be used to effectively photograph droplets from a large array of nozzles, for example, droplets deposited in multiple columns and rows, which are rapidly processed by software in an image processing system. In one embodiment, the captured image may represent droplets from tens, potentially hundreds (or more) nozzles, all measured simultaneously. Figure 1 shows various options within the dashed box that can contribute to this purpose, for example: (a) capturing an image through the deposition surface opposite the print head, which is useful for velocity measurement (107); (b) capturing both droplets and nozzles in a simultaneously captured image, which facilitates the measurement of droplet position offset, bending, or velocity from each nozzle (109); (c) photographing droplets from each (multiple) nozzle simultaneously, for example, effectively measuring 40 or more nozzles at once (111); and (d) photographing a collection of multiple droplets, for example, 5 or more, that are measured simultaneously, rather than one droplet per nozzle. Note that in the latter case, image processing software can detect the volume of aggregated deposition (e.g., volume) or diffusion of droplet positions around the expected position, and can immediately identify other statistical parameters such as individual droplets, average, or distribution (diffusion) from a single captured image. Note that, depending on the embodiment, this may require that the standards be measured in advance and stored in the system. For example, when ink droplets are fixed in a deposition medium (i.e., tape), it can be difficult to detect the droplet volume. Such determination may rely on processing the droplet diameter, the color (or grayscale) value of the deposited droplet, or other means, and these values ​​are compared to calibration standards to produce accurate value calculations.

[0024] As described by figures 115 and 117, the system then calculates the measurements (for example, using an image processor running appropriate software) and stores them in memory (for example, random access memory such as in an available hard disk drive). In one embodiment, these values ​​are stored individually (i.e., one for each measurement of each parameter being measured for each nozzle), and in another embodiment, they are stored as a composite. The values ​​can be stored in a format that represents the fabric (for example, as the mean of a given nozzle for a given set of parameters, the total number of measurements, the standard deviation, etc.). As mentioned above, the values, once measured, can be used as needed to calculate statistical distributions, perform nozzle qualification / validation, and create "high-performance combinations" that are planned to match print scans to droplets with expected characteristics in a desired format.

[0025] Figure 2-4B is used to illustrate one embodiment of a modular droplet measurement system.

[0026] Figure 2 shows a close-up view of a first such system 201. This figure depicts a measurement window 203 (e.g., a glass-covered viewing window) through which an image is captured along a vector represented by the number 205. An optical detector, e.g., a camera, is located within the system 201 and takes a photograph through this window 203 along the direction of arrow 205. During operation, a transparent film tape from roll 207 is advanced through this window and held tightly against the window by a set of vacuum ports 209. After each measurement, the tape is advanced in the direction of the capstan 211 and accumulated in a waste roll (not visible) held within the chassis 213 of the droplet measurement system. Note that the depicted system is modular and is moved as a unit to position the measurement window 203 (and the associated measurement area defined by this window) in close proximity to any printhead nozzle to be measured, for example, at a "standard deposition depth" on the nozzle plate of the printhead. In optional embodiments, the droplet measurement system 201 can be articulated in three dimensions so that it can be positioned adjacent to other nozzle sets and so that the deposition height can be varied as desired.

[0027] Figure 3 is an internal cross-sectional view of the droplet measurement system 301. The system also includes an optical system comprising a viewing window 303 through which an image is captured, an optical unit assembly 305, a camera 307, and a light source 309. A stepping motor 311 selectively advances the optical unit assembly 305 linearly with respect to the viewing window 303, i.e., in the direction indicated by the arrow 313. It should be noted that the term “camera” as used herein can optionally refer to any type of sensor, i.e., a simple linear sensor comprising individual optical sensors can be used, for example, it is possible to “scan” such a linear sensor back and forth to image the entire viewing window 303 using the stepping motor 311. In other embodiments, the camera captures an image representing an array of pixels in the viewing area through any conventional means, e.g., using a commercially available photographic camera, a charge-coupled element array, ultraviolet or other invisible radiation capturing device, or other means. It should be noted that camera movement (i.e., scanning movement) is not required in all embodiments. In the embodiment described, the optical assembly 305 also includes an internal beam splitter that allows light to pass from the light source (e.g., to the viewing window 303) but redirects the reflected light towards the camera 307 using a mirror for image capture. As should be obvious, light from the light source passes through the viewing window, through the transparent tape, reflects off the print head (not shown in Figure 3), passes through the transparent tape again, receives any focusing or other optical elements, is captured, and processed for analysis. Thus, the captured image provides a visible indicator of the position of each nozzle being measured (e.g., this image is captured from the reflection by the nozzle plate) and also shows any overlay of any deposited droplets (which are transparent but distinguishable from the film). That is, in the manufacturing process considered (specifically for OLED display processing, e.g., for the encapsulation layer), the deposited material is semi-transparent and therefore does not obstruct the image capture of the nozzle plate. Figure 3 also shows a capstan 315 for transporting the transparent tape, and a mechanism to cure any deposited ink to prevent the transfer of the deposited ink to any other system components. The ultraviolet curing bar 317 is also shown. Figure 3 also shows an interface and control panel 319 used for controlling various system components and for controlling image acquisition. The interface and control panel 319 also controls the transport of the film tape by controlling, for example, film roll motors 321 and 323 used for film intake and supply rolls (not separately identified in this figure), respectively. Image processing can be performed locally on the interface and control panel 319, or alternatively, in a processor within the manufacturing apparatus or in a remote computer, depending on the embodiment.

[0028] Figures 4A and 4B show perspective views of the droplet measurement system 301 from Figure 3. Figure 4B represents a rear view of the unit relative to Figure 4A, i.e., from the viewpoint provided by arrow BB in Figure 4A. More specifically, these figures identify the viewing window 303, vacuum port 403, UV curing bar 317, tape supply roll 405 and intake roll 407, frame and optical chamber 409 (housing the interface and control panel 319 as previously mentioned). During operation, unused tape is supplied in the direction indicated by arrow 411 and adheres tightly to the viewing window 303 as previously referenced. From this point, the film is advanced downwards toward the UV curing bar 317 via the capstan 315 along arrow 412 for the purposes described above. The operation of the UV curing bar is controlled by the interface and control panel 319 using built-in firmware or software stored on a non-transient machine-readable medium. Finally, after curing, the film is advanced to the take-up roll 407, generally as indicated by arrow 415. As should be obvious, the entire unit is modular and provides easy removal and repair, for example, to remove the used take-up roll 407 of the transparent deposition tape and to replace the supply roll 405 and store an unused one.

[0029] Figure 5A presents a flowchart associated with one embodiment 501 of a method for performing droplet measurement. As previously stated, it may be desirable to perform measurements in situ, i.e., directly within the processing apparatus, to dynamically update the values ​​of one or more droplet parameters for process, lifetime, temperature, or other factors. For this purpose, the measurements are advantageously performed in the printer's service station, for example, while a new substrate is being loaded, unloaded, cured after deposition, or otherwise during idle time before actual printing. As shown in figure 503, one or more printheads (e.g., mounted in a common printhead assembly) are advanced to the service station and "stationed" for maintenance operations. Such maintenance operations may include various calibrations, printhead replacements, nozzle purging or other quality treatments, droplet measurement, as considered by this disclosure or for other purposes. As will be described in more detail below, it may be desirable to perform printing in a controlled atmosphere with respect to OLED display processing applications (and for processing of other devices such as solar panels). Therefore, in many applications, the “resident” position will be in a location accessible from the outside (e.g., for printhead replacement) without venting the entire processing apparatus or printer into an uncontrolled atmosphere, for example. That is, such a second chamber is preferably made small in size relative to any print enclosure, for example, occupying 2 percent or less of the overall print chamber volume, to minimize ventilation (if any). Once the printheads are resident, they are sealed to the second controlled atmosphere and a droplet measurement system (a “DMU” for droplet measurement unit) is selectively engaged to perform measurements (505). If printing is performed on an intermittent basis for the nozzle movement window (e.g., different sets of nozzles are measured or remeasured between print runs as the substrate is loaded and unloaded as described above), as described by the optional process block 507, the system reads the start address to position the DMU to capture a selected subset of nozzles.It should be noted that the system may employ an alignment process to identify the corner nozzles of each printhead (for example, updated when the printhead is replaced so that the system is calibrated to "grasp" the approximate position of each nozzle). Such an alignment process may be performed by using an approximate position address and retrieval process (e.g., a spiral retrieval algorithm) to image the corner nozzles of each array and thereby articulate the DMU (and its camera) to locate them, using this process. The control over position throw is extremely precise in the system described, for example, to about 1 micron, and typically, recalibration of the printhead and droplet measurement system positioning is not required unless system components are manually replaced (e.g., the DMU or printhead is removed or repaired). Once the transparent tape (i.e., the droplet deposition surface for testing) is in place, the system controls the monitored printhead nozzles to deposit a controlled number of droplets (rapidly and consecutively, if multiple droplets are measured per nozzle) as indicated by the number 509. Simultaneously, the image capture system within the DMU images the deposited ink and nozzle locations (e.g., by capturing light reflected by the printhead through the transparent tape and ink). Note that, as indicated by the number 511, in one embodiment, the image capture is performed in color so as to be able to identify the ink density in any deposited ink droplet (e.g., which would impart subtle color properties depending on the material or thickness while being semi-transparent). Also, as indicated by the number 511, the captured image can be filtered (e.g., for color, intensity, gamma, or one or more other desired parameters) to produce a filtered image, and after such filtering (or as part of such filtering), the captured image is converted to grayscale as indicated by the number 513.Multiple images, for example, a first image representing the nozzle and a second image representing the deposited droplet, can also be generated from this process according to their respective filters, and it should be noted that, clearly, many permutations exist. The image processing software then uses the output grayscale image to identify the nozzle, the ink droplet, the positional difference between the nozzle and the ink droplet, the droplet volume, the droplet diameter, the droplet shape, and / or any other desired parameters (515 / 517). As should be obvious, it is not necessary for all embodiments to measure all of these. For example, in a system for calculating droplet volume, it may not be necessary to image the nozzle itself or analyze the droplet shape or position. Conversely, in such embodiments (where the diffusion of multiple droplets is being analyzed), it may be important to determine the scale of the droplet positional deviation or to perform color analysis to appropriately calculate the volume. The parameters measured will generally depend on the implementation and the desired results. As indicated by the figure 517, whatever parameters are measured, the system calculates one or more measurements or parameter offsets using optional standard 519, for example, as previously referenced. Such parameter offsets or values ​​can be calculated for droplet or nozzle position, droplet timing, or droplet volume, or any combination thereof, as referenced by the figure 521. The system then updates a stored information repository, which is local or remote to the DMU (523), and then, by optional process 525, stores the position for the next measurement iteration and advances the tape. The process then terminates, and the system is ready for another measurement iteration (which may be performed immediately or later, for example, after the next substrate run).

[0030] As referenced by figures 529-533, the calculation of parameters and / or any positional offsets may optionally be performed by one or more processors executing suitable software (instructions stored on a processor-readable medium), such processors typically store image data in processor-accessible memory, isolate the image data for each nozzle, calculate parameters from each image data, and also store the per-nozzle parameters in processor-accessible memory.

[0031] Figures 5B and 5C show sampled images 551 and 571, respectively. The first of these, image 551, represents a photograph of approximately 40 nozzles as a subset of the printhead. Note how the nozzles are arranged alternately row by row to provide an option for proximity pitch variation of the cross-scan axis (for example, droplets intended for a specific substrate position can be printed from any row of nozzles, providing a deposition accuracy of less than 20 microns in some embodiments). Figure 5B then shows a color image that can be filtered and / or converted to grayscale as appropriate, as well as a grayscale image after such filtering or conversion (i.e., color drawings are generally not used or permitted in patent applications). Note that in this embodiment, the nozzles are not imaged or illustrated separately, but this may be done in other embodiments. The second image 571 (Figure 5C) shows the image from Figure 5B after filtering and gradient processing to identify droplet diameters. Specifically, Figure 5C shows a white circle corresponding to the droplet diameter, with a clearly defined droplet boundary. Image processing calculates the centroid (for example, by calculating the maximum horizontal and vertical diameters of such “circles”, and by taking an inner Cartesian coordinate point along each diameter so associating each droplet with a specific xy Cartesian position). This position can then be compared to the nozzle position to determine the offset, and the system identifies inter-nozzle offset variations for the purpose of print planning. These images can also represent droplet volume processing; for example, image processing software can calculate the diameter and / or area and / or associated color of each droplet, compare this to a factory-defined standard or a standard defined in-situ, calculate the size and density, and from these calculate the volume. Almost any desired droplet parameter can be measured in this way.

[0032] While the details of the droplet measurement system have been described in this manner, here we will describe its application to manufacturing and industrial processing equipment / printers. More specifically, the following discussion will describe exemplary systems for making such prints that can be applied to the manufacture of solar panels and / or display devices that can be used in electronic devices (e.g., as smartphones, smartwatches, tablets, computers, televisions, monitors, or other forms of displays). The manufacturing techniques provided by this disclosure are not limited to these specific applications and can be applied, for example, to any 3D printing application and a wide range of other forms of products.

[0033] Figure 6A represents several different implementation layers, collectively designated by reference numeral 601. Each of these layers represents a possible discrete implementation of the techniques described herein. Firstly, the techniques described herein can take the form of instructions stored on a non-transient, machine-readable medium (e.g., executable instructions or software for controlling a computer or printer), as represented by graphic 603. For example, the disclosed techniques can be embodied as software adapted to cause a manufacturing apparatus (or an included printer) to measure one or more droplet parameters using the optical measurement techniques disclosed herein. Secondly, as indicated by computer icon 605, these techniques can also optionally be implemented as part of a computer or network, for example, within a company designing or manufacturing components for sale or use in other products. Thirdly, as illustrated using the storage medium graphic 607, the previously introduced techniques can take the form of stored printer control instructions, which, when acted upon, will cause the printer to process one or more layers of components in a manner that depends on droplet measurement and associated planning (e.g., scan path planning or nozzle qualification, as discussed herein). Printer instructions may be transmitted directly to the printer, for example, via a LAN or WAN, and in connection therewith, the depicted storage medium graphic may (but not limited to) It should be noted that this may represent a server, a portable device, a laptop, another form of computer, or a portable medium such as RAM or a flash drive located inside or accessible from a printer. Fourthly, as represented by the processing device icon 609, the techniques described above may be implemented as part of a processing apparatus or machine, or in the form of a printer within such apparatus or machine (e.g., as a droplet measuring system by the techniques disclosed herein, as a manufacturing method, as software for controlling the droplet measuring system, etc.). It should be noted that a particular depiction of processing device 609 represents an exemplary printer device, which will be discussed in relation to Figures 6B, 7A, and 7B below. The techniques described above may also be embodied as a finished or partially finished manufactured component or an assembly of manufactured components (e.g., manufactured in relation to the patented process). For example, in Figure 6A, several such components are depicted in the form of an array 611 of semi-finished flat panel devices, which will be separated and sold for incorporation into end consumer products. The described device may have, for example, one or more encapsulation layers, or other layers processed in accordance with the techniques described above. The techniques described above can also be embodied in the form of end consumer products such as a display for a portable digital device 613 (e.g., an electronic pad or smartphone), a television display screen 615 (e.g., an OLED TV), a solar panel 617, or other types of devices.

[0034] Figure 6B shows one considered multi-chamber processing apparatus 621 that may be used to apply the techniques disclosed herein. Generally speaking, the depicted apparatus 621 includes several general modules or subsystems, including a transfer module 623, a printing module 625, and a processing module 627. Each module maintains a controlled environment so that printing can be performed, for example, by the printing module 625 in a first controlled atmosphere, and other processing, such as inorganic encapsulation layer deposition or another deposition process (for example, for printed materials), can be performed in a second controlled atmosphere. The apparatus 621 uses one or more mechanical handlers to move substrates between modules without exposing the substrates to an uncontrolled atmosphere. Within any given module, it is possible to use other substrate handling systems and / or specific devices and control systems adapted to the processing performed on that module.

[0035] Various embodiments of the transfer module 623 may include an input load lock 629 (i.e., a chamber that provides buffering between different environments while maintaining a controlled atmosphere), a transfer chamber 631 (which also has a handler for transporting substrates), and an atmospheric buffer chamber 633. Within the printing module 625, other substrate handling mechanisms such as a floating table can be used for stable support of the substrates during the printing process. In addition, xyz motion systems such as split axis or gantry motion systems can be used for precise positioning of at least one print head relative to the substrate, and a y-axis transport system is provided for transporting substrates through the printing module 625. It is also possible to use multiple inks for printing in the printing chamber, for example, using separate print head assemblies, so that, for example, two different types of deposition processes can be carried out within the printing module in a controlled atmosphere. The printing module 625 may include a gas enclosure 635 that houses the inkjet printing system, which introduces an inert atmosphere (e.g., nitrogen) and separately means for controlling the atmosphere (e.g., temperature and pressure), gas components, and the presence of particulate matter for environmental conditioning.

[0036] Various embodiments of the processing module 627 may include, for example, a transfer chamber 636, which also has a handler for transporting substrates. The Joule may also include an output load lock 637, a nitrogen stack buffer 639, and a curing chamber 641. In some applications, the curing chamber can be used to cure, bake, or dry a monomer film into a uniform polymer film. For example, two specifically considered processes include a heating process and an ultraviolet radiation curing process.

[0037] In one application, the apparatus 621 is adapted for the mass production of liquid crystal display screens or OLED display screens, for example, for processing an array of eight screens at once on a single large substrate. These screens can be used as display screens for televisions and other forms of electronic devices. In a second application, the apparatus can also be used in the same manner for the mass production of solar panels.

[0038] The printing module 625 can be used in applications to deposit an encapsulation layer, which is advantageous in that it helps protect sensitive elements of an OLED display device. For example, the depicted apparatus 621 can be loaded with a substrate and controlled to move the substrate back and forth between various chambers in a manner that is not interrupted by exposure to an uncontrolled atmosphere during the encapsulation process. The substrate can be loaded via an input load lock 629. A handler positioned in the transfer module 623 can move the substrate from the input load lock 629 to the printing module 625, and following the completion of the printing process, the substrate can be moved to the processing module 627 for curing. Through repeated deposition of subsequent layers, each of controlled thickness, the total encapsulation or other layer thickness can be accumulated to suit any desired application. Again, it should be noted that the techniques described above are not limited to encapsulation processes or OLED processing, and many different types of tools can be used. For example, the configuration of the device 621 can be varied to arrange various modules 623, 625, and 627 in different juxtapositions, and additional, fewer, or different modules can also be used.

[0039] Figure 6B provides one embodiment of a set of connected chambers or processing components, although clearly many other possibilities exist. The techniques described above can be used with the device depicted in Figure 6B, or in fact, to control processing processes carried out by any other type of deposition equipment.

[0040] Figures 7A–7C are generally used to introduce the techniques and structures used for droplet measurement and verification per nozzle.

[0041] More specifically, Figure 7A provides an illustrative diagram depicting a droplet measurement system 701 and a relatively large printhead assembly 703, the printhead assembly having multiple printheads (705A / 705B) each with a number of individual nozzles (e.g., 707) in which hundreds to thousands of nozzles exist. An ink supply unit (not shown) is fluidically connected to each nozzle (e.g., nozzle 707), and a piezoelectric transducer (also not shown) is used to eject droplets of ink under the control of an electronic control signal per nozzle. The nozzle design maintains a slight negative pressure of ink at each nozzle (e.g., nozzle 707) to avoid flooding of the nozzle plate, and an electronic signal to a given nozzle is used to activate the corresponding piezoelectric transducer, pressurizing the ink for the given nozzle, thereby ejecting a droplet from the given nozzle. In one embodiment, the control signal to each nozzle is typically 0 volts, and a positive pulse or signal level at a given voltage is used to cause a specific nozzle to eject a droplet (one per pulse) from that nozzle. In another embodiment, different tuned pulses (or other more complex waveforms) can be used per nozzle. However, in relation to the embodiment provided by Figure 7A, liquid It should be assumed that it is desirable to measure the volume of droplets produced by a specific nozzle or a specific set of nozzles (e.g., nozzle 707) from which droplets are ejected downward from the print head toward the chassis 709 on which the deposition film is mounted (i.e., in the direction of "h" which represents the z-axis height relative to the three-dimensional coordinate system 708). As mentioned above, in embodiments using current droplet deposition from many nozzles, the target surface is advantageously fixed in a known position relative to the print head (i.e., so that it is known which deposition droplet belongs to which nozzle). The dimension of "h" is typically about 1 millimeter or less, and there are thousands of nozzles (e.g., 10,000 nozzles) each having a droplet thus individually measured in the working printer, and the deposition surface is modified or advanced stepwise to multiple windows where many (e.g., tens to hundreds) droplets will be imaged and measured simultaneously. Therefore, in order to precisely optically measure droplets from each nozzle, a technique is used in the disclosed embodiments to properly position the droplet measurement system 701, the print head assembly 703, or elements of both relative to each other for optical measurement.

[0042] In one embodiment, these techniques utilize a combination of (a) xy motion control (711A) of at least a portion of the optical system (e.g., in a dimensional plane 713) for precisely positioning a measurement area 715 presented by the system in direct proximity to any nozzle or set of nozzles generating droplets for optical calibration / measurement, and (b) subplane optical retrieval (711B) (e.g., thereby enabling easy positioning of the measurement area adjacent to any nozzle despite the large printhead surface area). Thus, in an exemplary embodiment having about 10,000 or more print nozzles, the motion system can position at least a portion of the optical system at (e.g.) as many as 10,000 discrete positions in close proximity to the discharge path of each nozzle of the printhead assembly. The optical portion is typically adjusted to a fixed position so that a precise focus is maintained on the measurement area to capture deposited droplets on a transparent film or other deposition medium, as described. It should be noted that, since typical droplets can have a diameter of approximately several microns, the optical arrangement is typically extremely precise and presents challenges regarding the relative positioning of the printhead assembly and the measuring optics / measurement area. In some embodiments, to assist this positioning, the optical components (mirrors, prisms, etc.) are used to orient a light capture path for sensing below the dimensional plane 713 arising from the measurement area 715, so that the measuring optics can be positioned close to the measurement area without interfering with the relative positioning of the optical system and the printhead. This allows for effective positional control in a manner not constrained by the millimeter-order deposition height h, where each droplet is deposited and imaged, or where a large x and y width is occupied by the monitored printhead. Optionally, separate light rays incident from different angles can be used to image the film or deposition surface from below, or a coaxial image capture system with a beam splitter can also be used. Other optical measurement techniques can also be used.In an optional aspect of these systems, the motion system 711A is fabricated to be an xyz motion system that allows for optional and advantageous selective engagement and disengagement of the droplet measurement system without moving the printhead assembly during droplet measurement. Briefly, in industrial processing devices having one or more large printhead assemblies, it is considered that, in order to maximize manufacturing uptime, each printhead assembly will sometimes be "stationed" at a service station to perform one or more maintenance functions, and given the sheer size of the printhead and the number of nozzles, it may be desirable to perform multiple maintenance functions on different parts of the printhead at once. In this regard, in such embodiments, it may be advantageous to move the measurement / calibration device around the printhead rather than the other way around. [This then also allows for engagement of other non-optical maintenance processes, for example, on other nozzles, if desired.] To facilitate these operations, the printhead assembly may optionally have a system for identifying a specific group or range of nozzles to be optically calibrated. Consequently, the printhead assembly can be “stationed” as described. Once the printhead assembly or a given printhead is stationary, the motion system 711A engages in moving at least a portion of the optical system relative to the “stationed” printhead assembly to precisely position the measurement area 715 in a suitable position for detecting droplets ejected from each group of nozzles, and the use of the z axis of movement allows for selective engagement of the photorecovery optics from well below the surface of the printhead, facilitating other maintenance operations in place of or in addition to optical calibration. Perhaps to put it another way, the use of the xyz motion system allows for selective engagement of the droplet measurement system, independent of other tests or test devices used in a service station environment. For example, in such a system, one or more printheads of the printhead assembly can also be selectively replaced while the printhead is stationary. Note that this structure is not required in all embodiments, and other alternatives are possible in which only the printhead assembly moves (or one of the printheads is moved) and the measurement assembly is stationary, or where stationary of the printhead assembly is not required.

[0043] Generally speaking, the optical unit used for droplet measurement would include a light source 717, an optional set of light-transmitting optics 719 (which direct light from the light source 717 to the measurement area 715 as needed), one or more light sensors 721, and a set of recovery optics 723 that direct light used for droplet measurement from the measurement area 715 to one or more light sensors 721. The motion system 711A optionally moves one or more of these elements together with the chassis 709 (for example, together with the imaging area) in a manner that allows for the directing of light after droplet measurement from the measurement area 715 to a subsurface location. In one embodiment, the light-transmitting optics 719 and / or the light-recovery optics 723 use mirrors that direct light to / from the measurement area 715 along a vertical dimension parallel to the droplet's movement, and the motion system moves each of the elements 709, 717, 719, 721, and 723 as an integrated system during droplet measurement. This configuration offers the advantage that the focus does not need to be recalibrated relative to the measurement area 715. As described by figure 711C, the light-delivering optics unit is also optionally used to supply light source from a location below the dimensional plane 713 of the measurement area, for example, both the light source 717 and the light sensor 721 direct / collect light from below the measurement area, as generally illustrated. As described by figures 725 and 727, the optical system may optionally include lenses for focusing purposes, as well as photodetectors (for example, for non-imaging techniques that do not rely on the processing of multi-pixel "photographs"). Again, the optional use of z-motion control relative to the chassis allows for optional engagement and disengagement of the optical system at any point while the printhead assembly is "stationed," as well as precise positioning of the measurement area 715 in proximity to any group of nozzles. Such stationing of the printhead assembly 703 and xyz motion of the optical system 701 are not required in all embodiments. Other combinations and permutations are also possible.

[0044] Figure 7B provides a process flow associated with droplet measurement for several embodiments. This process flow is generally designated using the figure 731 in Figure 7B. More specifically, as indicated by reference figure 733, in this particular process, the printhead assembly is first stationed, for example, at a service station (not shown) of a printer or deposition device. Then, the droplet measuring device is engaged with the printhead assembly by selective engagement of part or all of the droplet measuring system, through movement, for example, from below the deposition surface, to a position where the optical system of the droplet measuring system can simultaneously measure droplets from many nozzles (735). As indicated by figure 737, the relative motion of one or more optical systems with respect to the stationed printhead can be performed arbitrarily in the x, y, and z dimensions.

[0045] As shown in the aforementioned patent application incorporated by reference, even a single nozzle and associated nozzle ejection drive waveform (i.e., pulse or signal level used to eject droplets) can generate droplet volume, trajectory, and velocity that vary slightly from droplet to droplet. According to the teachings herein, in one embodiment, a droplet measurement system optionally obtains n measurements of a parameter per droplet to derive a statistical confidence in the expected properties of a desired parameter, as indicated by the figure 739. In one implementation, the measured parameter may be volume, while in another implementation, the measured parameter may be flight velocity, flight trajectory, nozzle position error (e.g., nozzle bending), or another parameter, or a combination of several such parameters. In one implementation, “n” may differ for each nozzle, while in another implementation, “n” may be a fixed number of measurements performed on each nozzle (e.g., “24”), and yet another implementation, “n” refers to a minimum number of measurements so that additional measurements can be performed to dynamically adjust the measured statistical properties of the parameter or to refine the confidence. Clearly, many modifications are possible. In relation to the aforementioned system, the measurement population can be accumulated immediately (i.e., by performing multiple droplet measurements on a given nozzle array during a single measurement iteration, i.e., without moving the droplet measurement system to a different set of nozzles), or by performing a single measurement and accumulating the measurement population through subsequent measurements (for example, as the measurements continuously advance through the circular range of the nozzles over time).

[0046] In the embodiment provided by Figure 7B, it is assumed that droplet volumes are measured to obtain an accurate average representing the expected droplet volume and tight confidence interval from a given nozzle. This allows for the arbitrary planning of droplet combinations (using multiple nozzles and / or drive waveforms) while ensuring the distribution of composite ink filling in the target area is maintained around the expected target (i.e., for composite droplet averages). As described by optional process boxes 741 and 743, the optical measurement processes considered ideally allow for instantaneous or near-instantaneous measurement and calculation of the volume (or other desired parameters) of many nozzles at once, for example, using a transparent film and under-deposition capture (i.e., from the opposite side of the film to the one used for deposition), and with such high-speed measurements, it becomes possible to frequently and dynamically update the volume measurements to address changes over time in, for example, ink properties (including viscosity and constituent materials), temperature, nozzle clogging or lifespan, and other factors. Based on this, for example, using a printhead assembly with 10,000 nozzles, it is expected that large measurement groups for each of thousands of nozzles can be obtained in minutes, ensuring that droplet measurements can be performed frequently and dynamically. As mentioned above, in one optional embodiment, droplet measurements (or measurements of other parameters such as trajectory and / or velocity) can be performed as a periodic intermittent process, and the droplet measurement system can be performed according to a schedule, or between substrates (e.g., as substrates are loaded or unloaded), or stacked against other assemblies and / or other printhead maintenance processes, so as to effectively collect many data points over many measurement intervals (thus constructing a statistical distribution representing each nozzle). With regard to embodiments that allow alternative nozzle drive waveforms to be used in a manner specific to each nozzle, it should be noted that such a rapid measurement system facilitates the adjustment of planned scan paths, nozzle qualification / disqualification, and planned droplet combinations of droplets generated by various nozzle-waveform pairings, as previously suggested and incorporated by reference in the aforementioned patent applications.The figures 745 and 747 allow for highly precise droplet planning, where the expected droplet volume can be measured to an accuracy of 0.01 pL or better, enabling (ideally) planning with a resolution of 0.01 pL, and in one embodiment, measurement errors are effectively reduced to provide a 3σ confidence level (or other statistical measures such as 4σ, 5σ, 6σ, etc.) for the allowable droplet volume. The same applies to droplet position and / or velocity and / or nozzle bending. For example, highly precise deposition can be achieved by measuring the expected position to an accuracy of 1 micron or better (or another distance measure). It becomes possible to provide, and the expected position can be assumed to be within a range of specific Cartesian points and standard deviations (or, for example, 4σ, 5σ, 6σ diffusion) around such a point. Once sufficient measurements have been made for various droplets, the filling with combinations of these droplets can be evaluated and used to plan printing (748) in the most efficient manner possible. As indicated by the separation line 749, droplet measurements can be performed by intermittently switching back and forth between the active “online” printing process and the “offline” measurement and calibration process. Note that, in order to minimize manufacturing system downtime, measurements are typically performed while the printer is subject to other processes, for example, between substrate loading and unloading. By figure 751, in one embodiment, a transparent film or tape can be specially selected (or treated) to optimize the capture of droplet properties of a particular ink during analysis (i.e., given chemical or fluid properties of the ink) for the purpose of facilitating image capture and / or analysis. For example, inks in some applications are monomers that will be subsequently cured by an ultraviolet curing process to become polymers, and transparent films can be selected to have physical, color, absorbance, fixation, curing, or other properties to facilitate the capture of droplet properties, thereby increasing the predictability that such materials can be analyzed by an image capture system. Finally, according to Figure 753, the film (tape) or droplet measurement system (or both) as a whole can be designed for modular replacement to minimize downtime of the measurement and printing systems.

[0047] During printing, nozzle (and nozzle waveform) measurements can be performed on a rolling basis, advancing through a series of nozzles with each interruption during the substrate printing operation. Whether engaging in measuring all nozzles anew or using such a rolling basis, the same basic process shown in Figure 7B can be employed for measurement. In this regard, when the droplet measurement device is engaged for a new measurement (either immediately after a pre-measurement or immediately after a substrate printing operation), the system software loads a pointer that identifies the next set of nozzles to be measured (e.g., with respect to the second printhead, "the nozzle window with the upper left corner at nozzle 2,312"). In the case of an initial measurement (e.g., in response to a periodic process such as the installation of a new printhead, a recent startup, or a daily measurement process), the pointer will point to the first nozzle of the printhead, e.g., "nozzle 2,001". This nozzle is either associated with a specific image grating access or referenced from memory. The system anticipates the droplet measurement system (e.g., a previously referenced measurement area). The provided address is used to advance the nozzle to a position corresponding to its position. Note that in a typical system, the mechanical throw associated with this movement is extremely precise, i.e., precise to nearly micron resolution. The system optionally searches for the nozzle position at this point in time for the expected micron resolution position, locating the nozzle and centering its position based on image analysis of the printhead within a distance of only a few microns from the estimated grid position. For example, zigzag, spiral, or other search patterns can be used to search for nozzles or reference expected positions that have a predetermined positional relationship to a desired set. The typical pitch distance between nozzles can be approximately 250 microns, while the nozzle diameter can be approximately 10–20 microns.

[0048] Figure 7C shows a flow chart relating to nozzle qualification. In one embodiment, droplet measurements are performed to produce statistical models (e.g., distribution and mean) for each nozzle and for each waveform applied to any given nozzle, for any one and / or for droplet volume, velocity, and trajectory. Thus, for example, if there are two selections of waveforms for each of 12 nozzles, there are up to 24 waveform-nozzle combinations or pairs. In one embodiment, measurements of each parameter (e.g., volume) are performed for enough nozzles or waveform-nozzle pairs to generate a robust statistical model. It should be noted that, despite the plan, it is conceptually possible that a given nozzle or nozzle-waveform pair may produce an average with an exceptionally wide distribution or one that is so abnormal as to require special treatment. Such special treatment applied in one embodiment is conceptually represented by Figure 7C.

[0049] More specifically, the general method is represented using reference figure 781. The data generated by the droplet measurement device is stored in memory 785 for later use. During the application of method 781, this data is retrieved from memory, and the data for each nozzle or nozzle-waveform pair is extracted and processed individually (783). In one embodiment, a normal random distribution is constructed so that each variable is considered eligible, represented by the mean, standard deviation, and the number of droplets measured (n), or using an equivalent measure. Note that other distribution forms (e.g., Student's T, Poisson, etc.) may be used. The measured parameters are compared to one or more ranges to determine whether the relevant droplet can be used in practice (787). In one embodiment, at least one range is applied so that the droplet is considered ineligible for use (e.g., if the droplet has a volume that is sufficiently large or small for the desired target, the nozzle or nozzle-waveform pair may be excluded from short-term use). To provide examples, if a 10.00 pL droplet is desired, for example, nozzles or nozzle waveforms associated with a droplet mean that are more than 1.5% away from the target (e.g., <9.85 pL or >10.15 pL) may be excluded from use. Alternatively, range, standard deviation, variance, or another diffusion measure may be used. For example, if it is desired to have a statistical model of droplets with a narrow distribution (e.g., 3σ < 1.005% of the mean), droplets with measurements that do not meet this criterion may be excluded. It is also possible to use an elaborate / complex set of criteria that consider multiple factors. For example, an anomalous mean combined with very narrow diffusion may be accepted; for example, if the diffusion (e.g., 3σ) away from the measured (e.g., anomalous) mean μ is within 1.005%, then the relevant droplet may be used. For example, if it is desired to use droplets with a 3σ volume of 10.00 pL ± 0.1 pL or less, a nozzle-waveform pair that produces a 9.96 pL average with a 3σ value of ±0.8 pL may be excluded, but a nozzle-waveform pair that produces a 9.93 pL average with a 3σ value of ±0.3 pL may be acceptable.Clearly, many possibilities are possible according to any desired rejection / abnormality criteria (789). It should be noted that the same type of processing can be applied to the flight angle and velocity per droplet, i.e., the flight angle and velocity per nozzle-waveform pair will exhibit a statistical distribution, and it is expected that some droplets can be excluded depending on the measurement and statistical model derived from the droplet measuring device. For example, droplets with an average velocity or flight trajectory that is outside the normal 5%, or with a velocity dispersion outside a particular target, can be hypothetically excluded from use. Different ranges and / or evaluation criteria can be applied to each droplet parameter measured and provided by the storage device 785.

[0050] It should be noted that droplets (and nozzle-waveform combinations) may be processed and / or treated in different ways depending on rejection / abnormality criteria 789. For example, certain droplets that do not meet the desired criteria may be rejected (791), as described. Alternatively, additional measurements may be selectively performed for subsequent measurement iterations of a particular nozzle-waveform pair, and, as an example, additional measurements may be specifically performed on a particular nozzle-waveform pair to improve the tightness of the statistical distribution through additional measurements if the statistical distribution is too broad (e.g., variance and standard deviation depend on the number of data points measured). By figure 793, it is also possible to adjust the nozzle drive waveform to shape the waveform, for example, to use higher or lower voltage levels (e.g., to provide larger or smaller speeds or a more consistent flight angle), or to produce a modified nozzle-waveform pair that meets specific criteria. By figure 794, (e.g., a particular nozzle The waveform timing can also be adjusted (to compensate for the abnormal average velocity associated with the Zulu-waveform pairing). In an embodiment (as previously suggested), slower droplets can be fired earlier than other nozzles, and faster droplets can be fired later to compensate for a faster flight time. Many such alternatives are possible. Finally, by figure 795, any adjusted parameters (e.g., firing time, waveform voltage level, or shape) can be stored, and optionally, if desired, the adjusted parameters can be applied to remeasure one or more associated droplets. After each (modified or different) nozzle-waveform pairing has been deemed qualified (passed or rejected), the method then proceeds to the next nozzle-waveform pairing by figure 797.

[0051] The method described above can also be used to measure nozzle bending (and, naturally, to determine whether a nozzle is eligible or ineligible according to this criterion). That is, as an example, if we assume that a group of deposited droplets originates from a single, common, precise nozzle position but is clustered off-center in a direction perpendicular to the printhead substrate scan motion, then the nozzle in question may be offset relative to other nozzles in the same row or column. Such deviations can lead to an idealized droplet launch deviation, which can be taken into account when planning the precise combination of droplets; that is, any such “bend” or individual nozzle offset is remembered and used, as previously discussed, to determine whether a nozzle is eligible / ineligible or as part of the print scan plan, and the printing system uses the difference of each individual nozzle systematically rather than averaging these differences. In optional modifications, the same technique can be used to determine irregular nozzle spacing along the printhead scan direction (i.e., the high-speed printing axis), but with respect to the embodiments described, any such errors are incorporated into the correction of droplet velocity deviations (e.g., any such spacing is corrected by adjusting the nozzle velocity, which can be achieved, for example, by minor changes in the drive waveform used for a particular nozzle). To determine cross-scan axis bending that generates droplet clusters, each trajectory is effectively reverse-drawn (or otherwise mathematically applied) with other measured trajectories of the same nozzle and used to identify the average cross-scan axis position of the specific nozzle under monitoring. This position may be offset from the expected location of such nozzle, which may be evidence of nozzle bending.

[0052] As previously described and as suggested by this discussion, one embodiment constructs a statistical distribution of each nozzle for each parameter, for example, volume, velocity, trajectory, nozzle bend, and potentially other parameters, which are measured. As part of these statistical processes, individual measurements can be discarded or used to identify errors. To cite some embodiments, if a droplet measurement is obtained that has values ​​removed to some extent from other measurements of the same nozzle, which may represent a firing or measurement error, in one implementation, the system discards the measurement if it deviates to a point exceeding the statistical error parameter. If no droplets are observed at all, this may be evidence that the droplet measurement system is at the wrong nozzle (in the wrong position), or has a firing waveform error, or that the nozzle under monitoring is inoperable. Error handling processes can be employed to make appropriate adjustments, including taking any new or additional measurements as needed.

[0053] Although not separately referred to by Figures 7A-C, the depicted measurement process would typically be performed for each alternative waveform available for use with each nozzle. For example, if each nozzle has four different piezoelectric drive waveforms that can be selected, the measurement process could generally be repeated four times for each group of nozzles. If a particular implementation requires the construction of a statistical distribution based on 24 droplets for each waveform, there could be 96 such measurements for one nozzle (24 for each of the four waveforms, each measurement used to produce a statistical mean and diffusion measure of the estimated nozzle position, respectively, as well as the droplet velocity, trajectory, and volume, as well as (for example, for the purpose of assessing nozzle bending)). One Considered Embodiment Any number of waveforms can be shaped or otherwise generated, and the system measures droplet parameters associated with one or more pre-selected waveforms and then stores these parameters for later use in printing and / or print planning. These parameters can also be used to determine whether to keep (and store) a waveform for use in printing (for example, as part of a pre-selected set of acceptable waveforms) or to select a different waveform and measure its parameters.

[0054] Through the use of precision mechanical systems and droplet measurement system integration techniques, the disclosed method enables highly accurate measurement of individual nozzle characteristics, including the average droplet measurement criteria for each of the described parameters (e.g., volume, velocity, trajectory, nozzle position, and other parameters). As should be understood, the described technique promotes a high degree of uniformity and, therefore, enhanced reliability in manufacturing processes, particularly in OLED device manufacturing processes. Specifically, by providing control efficiency with respect to the accumulation of such measurements over other system processes in a manner calculated to reduce droplet measurement speed and overall system downtime, the teachings presented above help provide faster and less expensive manufacturing processes, designed to offer both flexibility and precision in the processing process.

[0055] Figure 8A shows a cross-sectional view of a typical layout within an industrial processing apparatus 801 (for example, associated with a printer in such an apparatus). More specifically, printing is assumed to take place within a printing enclosure chamber 803 so that the ambient atmosphere can be controlled ("controlled atmosphere"), and such control is typically performed to exclude unwanted particulate matter or otherwise to perform printing in the presence of a specific gas configuration (e.g., nitrogen, noble gas, etc.). Generally speaking, the substrate 813 is generally introduced into the printer using an atmospheric buffer chamber (not shown) and transported to a floating support table 815 using a mechanical handler that also aligns the substrate appropriately for printing via detection of one or more references on the substrate (these references, and cameras or other optical detectors used to detect the precise substrate position are not shown in Figure 8A). Printing is performed using a print head assembly 807 that is moved back and forth along a traveler 811 (as depicted by arrow 809) in the direction of the "low-speed printing axis". The printhead assembly 807 is described as a single object, but may be a composite assembly containing multiple printheads (e.g., 6, 10, or another number), each having hundreds to thousands of print nozzles (e.g., 2000 nozzles each). The printhead assembly 807 deposits liquid ink onto the substrate 813 at precise locations to a precise thickness, containing a material that will form a permanent layer of one or more products to be fabricated on the substrate 813. For example, such a material may be an organic or inorganic material, a conductor or insulator, a plastic, a metal, or other type of material. In a typical application, the substrate 813 is more than one meter wide and several meters long and is used to fabricate multiple OLED displays arranged on the substrate simultaneously, with each layer deposited as part of an integrated printing process that traverses all such “subpanels” (i.e., traverses multiple such displays being fabricated), where the individual displays are eventually cut from the substrate through a separate process.Each printing process can deposit different inks to a specified thickness, e.g., conductors, insulators, photogenerating elements, semiconductor materials, encapsulation, etc., using printing instructions specific to a particular layer. In an assembly line process, there may be multiple printers arranged at different positions or used in consecutive different deposition processes. With respect to OLED materials, ink is deposited for a specific layer, and after deposition, the substrate is removed from the chamber and advanced to a curing chamber (not shown) where the deposited ink can be cured, dried, heated, or otherwise processed to impart permanence to the deposited material. The depicted arrangement represents a “split axis” printer, i.e., the floating table 815 and associated handler (not shown) are located on the Y axis, near the lower right of the figure, on the dimensional reference 823. Note that the substrate will advance in and out of the drawing page along the direction of 825.

[0056] To perform droplet measurement, the printhead assembly 807 is typically selectively advanced outside the printing area to a point where it can be stationed within a service station, generally associated with a second enclosure environment 805. This second environment is optional but advantageous for enabling inspection, printhead replacement, and other maintenance without the need to ventilate the printing enclosure chamber 803. To station the printhead assembly 807, the assembly is generally moved to a location shown on the left side of the figure, and then advanced vertically to seal the printhead assembly 807 against the chamber for the second enclosure environment, as represented by the dashed-line position 819. In this "stationed" position, the droplet measurement system 817 can be controlled (e.g., in three dimensions) to selectively transport the measurement area to simulate substrate deposition height in proximity to any desired nozzle area.

[0057] As referenced above, it should be noted that in typical applications, it is desirable to keep the processing apparatus 801 “online” and in use as much as possible. In this regard, rather than performing droplet measurements at times when the apparatus 801 could be used for printing (and product manufacturing), in one embodiment, the measurement and printing are “ping-pong,” that is, during the time interval between printing operations, each time a substrate (e.g., 813) is loaded or unloaded, the printhead assembly 807 is advanced to the service station and partially calibrated (e.g., with respect to a rolling subset of the print nozzles and / or print nozzle waveforms) to build a solid set of measurements for each nozzle, updated to be up-to-date, and maintained in a manner that produces a statistical measurement population as previously described. It should be noted that any one of these features may be considered optional and is not essential for the practice of the disclosed technique.

[0058] Figure 8B is a plan view of the substrate and printer as they may appear during the deposition process, obtained along line BB in Figure 8A. The print enclosure chamber is again, generally, designated by reference numeral 803, while the second enclosure environment used for droplet measurement is generally designated by reference numeral 805. Within the print enclosure chamber, the substrate to be printed is again, designated by numeral 813, and the support table used to transport the substrate is generally designated by numeral 815. Generally speaking, any xy coordinate of the substrate is reached by a combination of movements, including x and y-dimensional movement of the substrate by the support table (e.g., using a floating support such as the one represented by numeral 857), generally represented by arrow 809, using the "slow axis" x-dimensional movement of one or more print heads 807 along the traveler 811. As described, the floating table and substrate handling infrastructure are used to move the substrate during printing along one or more "fast axes" as needed. The printhead is considered to have multiple nozzles 865, each individually controlled by a firing pattern derived from the print image (for example, so that the printhead moves from left to right along the “low-speed axis” and vice versa, to achieve printing of columns corresponding to printer grid points). Note that while only a few print nozzles are graphically depicted in the figure, in practice there are hundreds to thousands of such nozzles arranged in many columns and rows. When the relative motion between one or more printheads and the substrate is provided in the direction of the high-speed axis (i.e., the y-axis), the print typically represents a strip portion following individual rows of printer grid points. The printhead assembly can also be optionally rotated or otherwise adjusted by the number 867 to vary the effective nozzle spacing. Note that multiple such printheads can be used together, oriented with x-dimensional, y-dimensional, and / or z-dimensional offsets relative to each other as desired (see axis legend 823 in Figure 8B). The printing operation inks the entire target area (and any boundary area) as desired. The process continues until printing is complete, and the relative printhead assembly / substrate motion is represented by the vertical element of the depicted transport direction 857. After the deposition of the required amount of ink, the substrate is completed, for example, by the use of ultraviolet (UV) or other curing or hardening processes to form a permanent layer from the liquid ink. As previously mentioned, once the substrate is loaded or unloaded for printing, the printhead is advanced to the maintenance station and sealed in a second enclosure environment 805. In practice, this second enclosure environment, as described, is fabricated in a subset of the printing enclosure chamber 803 so that the printhead can be replaced without the need to ventilate the printing enclosure chamber as a whole. Within the second enclosure environment 805, the droplet measuring system 817 (considered to be located below the traveler 811 in the dashed line) is selectively engaged (again, advantageously, using the droplet measuring system as a whole, e.g., the three-dimensional articulation of its chassis) for measurements as previously referenced.

[0059] Figure 9 provides a chart illustrating the measured droplet positions relative to the expected positions of these droplets for each of many nozzles. More specifically, the chart generally shows a group of about 40 nozzles, designated by the number 901. Chart 901 is assumed to represent image data, processed above as described with reference to, for example, Figures 6A-C, to obtain the measured droplet positions (i.e., position 903, etc.) relative to the corresponding expected positions (i.e., position 904, etc.). Several features should be described with respect to Figure 9. Firstly, the nozzles are assumed to be arranged in rows of nozzles that are slightly alternating in fixed positions, as represented by graphic 905. This feature allows for extremely precise droplet spacing, for example, manufacturing tolerances such that nozzles are positioned hundreds of microns apart in the cross-scan direction, while slight alternating placements in each row allow for the use of alternative nozzles (e.g., a nozzle corresponding to position 906 relative to the nozzle corresponding to position 907, allowing for very close placement of droplets, for example, within 20 microns or less of any desired position on the substrate). Secondly, Chart 901 indirectly highlights the benefits provided by positional calibration of the droplet measurement system relative to the print head, emphasizing that it is crucial for the system to know exactly which nozzles correspond to positions 903 and expected positions 904 so that any measured data (and any nozzle qualification or adjustment) can be matched to the correct nozzles. Through image processing, precise positional offsets can be determined for each nozzle and taken into consideration in nozzle qualification and print planning. Finally, again, it should be noted that the use of transparent film potentially allows for image capture of not only deposited droplets but also nozzles (e.g., captured through the transparent film), facilitating the implementation of distance analysis by software. This is not required in all embodiments; for example, through an understanding of how the captured image of the film corresponds to the nozzle plate position, the software can also easily infer the nozzle position relative to the captured image and, based on this, calculate the position offset.In relation to Figure 9, the digit 904 represents the image nozzle position with an arbitrary deviation between the measured position 903 and the position 904 representing droplet velocity and / or bending, in one embodiment. While Figure 9 also shows the droplet position offset relative to the expected droplet position, similar analyses can also be used to measure droplet volume by comparing, for example, droplet color (e.g., grayscale value), droplet diameter, or other features of the captured image to a standard and calculating the droplet volume therefrom. Through the use of repeated additional measurements of each nozzle or nozzle-waveform pair, the system can easily construct a distribution of any desired droplet parameters on a per-nozzle or per-nozzle-waveform basis.

[0060] Figure 10 shows a flow chart 1001 associated with determining droplet volume from captured images. The captured image, represented by the number 1003, which represents droplets produced by the nozzle array, is first read from memory. This image is then read from memory, represented by the number 1005, to determine the droplet of interest (with varying color intensities, e.g., depending on the thickness on the deposition medium or ink density). The image is filtered as appropriate to separate only certain parts. Note that such filtered image may be a first, second, third, or other instance of filtration performed to measure specific parameters from a single image (for example, other instances may be used to calculate distance, position, offset, etc., for droplet velocity, position, nozzle position, etc.). The hue is then processed by the figure 1007 so that any hue correlates with ink thickness or density. For example, if the deposited ink has a slightly reddish tint, the "redder" parts of the image will typically represent greater thickness. In embodiments where multiple droplets are deposited from each nozzle at once, there may be multiple overlapping visible droplets, and note that the thickness processing 1007 preferably takes this into account to separate any individual droplets. This is not required in all embodiments; for example, if it is known that five droplets are deposited, it may suffice to calculate the total volume and divide by five. By figure 1009, the droplet radius is then calculated as previously referenced (or total ink coverage) and used in relation to the derived thickness measure to calculate the total deposited ink. Importantly, the transparent film used as the deposition surface may differ from the actual deposition surface (e.g., glass substrate) used in active printing, ideally which fixes the deposited ink. Therefore, as described by figure 1008, a stored standard specific to the deposition material is retrieved and used in relation to the thickness processing, volume calculation 1011, or both, to derive the correct droplet volume estimate. Finally, the measurement data is stored by figure 1013, and any calculated per-nozzle or per-nozzle-waveform distribution (e.g., average and diffusion) is updated for use in the print or scan plan. It should be noted that similarity comparisons with standards and raw value (or offset) calculations may be applied to many other parameters besides volume so as to suit specific applications.

[0061] Considering the various techniques and considerations presented above, the manufacturing process can be designed to enable rapid mass production of products at a low cost per system. By providing high-speed, repeatable printing techniques, for example, it is conceivable that printing can be substantially improved by reducing the printing time per layer to a fraction of the time that would otherwise be required without using the techniques described above. Returning again to the example of a large HD television display, it is conceivable that each color component layer can be accurately and reliably printed for a large substrate (e.g., an 8.5 generation substrate of approximately 220 cm x 250 cm) in 180 seconds or less, or even 90 seconds or less, representing a substantial process improvement. Improving the efficiency and quality of printing paves the way for a significant reduction in the cost of producing large HD television displays, and therefore for lower end consumer costs. As previously mentioned, display manufacturing (and specifically OLED manufacturing) is one application of the techniques presented herein, but these techniques can be applied to a wide variety of processes, computers, printers, software, manufacturing equipment, and end devices, and are not limited to display panels.

[0062] In the foregoing description and accompanying drawings, specific terminology and drawing symbols are provided to give a thorough understanding of the disclosed embodiments. In some cases, terminology and symbols may suggest specific details that are not necessary to practice these embodiments. The terms “exemplary” and “embodiment” are used to describe examples rather than preferences or requirements.

[0063] As shown, various modifications and changes can be made to the embodiments presented herein without departing from the broader spirit and scope of this disclosure. For example, any feature or aspect of an embodiment can be applied in combination with or in place of the other embodiment, at least if practical. Thus, not all features are shown in every drawing, and for example, a feature or technique shown according to an embodiment in one drawing may be, at will, not be shown herein. Even if not explicitly declared, it should be assumed that these features can be adopted as elements of, or in combination with, any other features of the drawings or embodiments. Therefore, this specification and the drawings should be considered illustrative rather than restrictive.

Claims

1. An inkjet printer, wherein the inkjet printer is A print head that ejects liquid droplets, The system comprises a droplet measurement unit, and the droplet measurement unit is The chassis includes a measurement window, an image acquisition system, and a film roll motor. Furthermore, the image capture system uses the print head to capture the liquid deposited on the film. To capture an image of a droplet, the optical assembly is movable relative to the measurement window, Furthermore, the droplet measurement unit, A supply roll that supplies the film to the measurement window and a receiving roll that receives the film Insertion roll and After capturing an image of the droplet by the image capture system in the droplet measurement unit, The droplets are cured, and the droplets are cured before the film reaches the intake roll. An inkjet printer, including a curing mechanism arranged in such a manner.

2. The chassis has a plurality of vacuum ports, and is an inkjet printer according to claim 1. Ta.

3. The vacuum port holds the film relative to the measurement window, as described in claim 2. Inkjet printer.

4. Furthermore, the film is supplied from the supply roll to the measuring window, and the film is supplied from the measuring window The film roll is equipped with a tape cartridge that receives the film, and the film roll The motor drives at least one of the supply roll and the take-up roll. The inkjet printer described in Item 1.

5. The inkjet printer according to claim 1, wherein the curing mechanism includes an ultraviolet light source.

6. Claim 5 further comprises a capstan for transporting the film to the curing mechanism. An inkjet printer.

7. The measurement window defines a plane, and the optical assembly is flush with the measurement window on the plane. The inkjet printer according to claim 2, which is movable in the row direction.

8. The curing mechanism is located below the capstan, as described in claim 6. Inkjet printer.

9. The tape cartridge further comprises a capstan adjacent to the measurement window, The intake roll is adjacent to the curing mechanism, as described in claim 4 of the inkjet printer Nta.

10. An inkjet printer, wherein the inkjet printer is A print head that ejects liquid droplets, The system comprises a droplet measurement unit, and the droplet measurement unit is Including a chassis, the chassis is Measurement window and The system includes a motor that linearly advances the film relative to the measurement window, and the measurement The window defines a plane, and furthermore, the chassis Image acquisition system and, Using the print head, an image of the droplets deposited on the film is generated. The system includes a curing mechanism that hardens the droplet after it has been captured using an image acquisition system, The image acquisition system is movable in a direction parallel to the plane relative to the measurement window. Inkjet printer.

11. The aforementioned droplet measurement unit uses a vacuum system and applies a vacuum to the measurement window. The inkjet printer according to claim 10, wherein the film is held in place.

12. The chassis further comprises a capstan adjacent to the measuring window, as described in claim 10. An inkjet printer.

13. The chassis further comprises a capstan adjacent to the measurement window, and the curing mechanism is , located below the capstan, the inkjet printer according to claim 10 Ta.

14. The inkjet printer according to claim 10, wherein the curing mechanism comprises an ultraviolet light source.

15. The film is supplied by a detachable supply reel, the ink according to claim 14. Jet printer.

16. The system further comprises a capstan for transporting the film from the measurement window to the curing mechanism. The inkjet printer according to claim 15.

17. The droplet measurement unit is movable relative to the print head, claim 1 or 1 The inkjet printer mentioned in item 0.

18. The droplet measurement unit is movable in three dimensions relative to the print head. The inkjet printer according to claim 17.

19. The measuring window is located between the first capstan and the second capstan, claim 1 Or the inkjet printer according to claim 10.

Images