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EP-4302340-B1 - APPARATUS AND METHOD FOR PRINTING ON A SUBSTRATE FOR DISPLAY MANUFACTURE

EP4302340B1EP 4302340 B1EP4302340 B1EP 4302340B1EP-4302340-B1

Inventors

  • CELLERE, GIORGIO
  • Furin, Valentina
  • NG, HOU T.
  • MACCARI, Andrea
  • ROSSI, PIERLUIGI

Dates

Publication Date
20260513
Application Date
20210301

Claims (15)

  1. An apparatus (100, 200) for printing on a substrate (150) for display manufacture, comprising: an alignment station (110) for aligning the substrate (150); a print station (120) for printing on the substrate (150); and an inspection station (130) for inspecting the printed substrate (150) for defects, wherein the alignment station (110), the print station (120) and the inspection station (130) are provided along a common axis (160), the common axis (160) is configured for moving the substrate (150) from the alignment station (110) to the print station (120) and from the print station (120) to the inspection station (130), the common axis (160) is further configured for moving the printed substrate (150), under the condition that a defect is detected in the inspection station (130), from the inspection station (130) back to the print station (120), and wherein the print station (120) is configured for reworking the printed substrate (150) to correct the detected defect by again printing on the substrate (150).
  2. The apparatus (100, 200) according to claim 1, wherein the common axis (160) comprises a stator of a linear motor.
  3. The apparatus (100, 200) according to claim 1 or 2, wherein the apparatus comprises a substrate holder, and wherein the substrate holder includes a reaction plate for engaging with a stator of a linear motor.
  4. The apparatus (100, 200) according to any of the preceding claims, wherein the alignment station (110) is configured for aligning the substrate (150) according to at least one of the following: fiducial markers provided on the substrate (150) and/or a substrate holder; an edge position of the substrate (150); and a position of features comprising a pixel structure provided on the substrate (150).
  5. The apparatus (100, 200) according to any of the preceding claims, wherein the print station (120) comprises a print head (401) for printing an ink on the substrate (150).
  6. The apparatus (100, 200) according to claim 5, wherein the ink comprises a fluorescent dye, including a UV-excitable fluorescent quantum dot dye.
  7. The apparatus (100, 200) according to any of the claims 5 or 6, wherein the print head (401) comprises a plurality of nozzles (420) for dispensing the ink, and wherein the plurality of nozzles (420) is arranged along a straight line, particularly wherein the print head (401) comprises a plurality of nozzles (420) with a spacing of at least 150 nozzles per inch or 2.54 cm, and/or particularly wherein the print head (401) comprises a plurality of nozzles (420) with at least 250 nozzles per line.
  8. The apparatus (100, 200) according to any of the preceding claims, wherein: the print station (120) comprises a print bar; the print bar comprises at least one print head (401) according to any of the claims 5 to 7; the at least one print head (401) is arranged such that the line of nozzles (420) of the at least one print head (401) is provided at an angle (560, 562) relative to the direction (510) of movement of the substrate (150) through the print station (120); and the angle (560, 562) of the line of nozzles (420) of the at least one print head (401) relative to the direction (510) of movement of the substrate (150) through the print station (120) is between 0° and 90°.
  9. The apparatus (100, 200) according to the preceding claim, wherein the print head (401) is arranged such that the angle (560, 562) of the print head (401) relative to the direction (510) of movement of the substrate (150) through the print station (120) is adjustable.
  10. The apparatus (100, 200) according to any of the claims 5 to 9, wherein the print head (401) is provided stationary within the print station (120) during printing.
  11. The apparatus (100, 200) according to any of the preceding claims, wherein the inspection station (130) comprises a visual inspection system, including a camera-based visual inspection system.
  12. The apparatus (100, 200) according to any of the preceding claims, further including a curing station configured for curing the substrate (150), wherein the common axis (160) is configured for moving the substrate (150) from the print station (120) to the curing station and from the curing station to the inspection station (130).
  13. A method (300) for printing on a substrate (150) for display manufacture, the method comprising: loading (302) the substrate (150) into a loading position provided along a common axis (160); moving (304) the substrate (150) along the common axis (160) from the loading position to an alignment station (110) provided along the common axis (160); aligning (306) the substrate (150); moving (308) the substrate (150) along the common axis (160) from the alignment station (110) to a print station (120) provided along the common axis (160); printing (310) on the substrate (150); moving (312) the printed substrate (150) along the common axis (160) from the print station (120) to an inspection station (130) provided along the common axis (160); inspecting (314) the printed substrate (150); under the condition that a defect is detected on the printed substrate (150), performing operations a.) through d.): a.) moving (320) the defective printed substrate (150) back along the common axis (160) from the inspection station (130) to the print station (120); b.) reworking (322) the defective printed substrate (150) to correct the detected defect by again printing on the substrate in the print station (120); c.) moving (324) the defective printed substrate (150) along the common axis (160) from the print station (120) to the inspection station (130); and d.) inspecting (326) the reworked printed substrate (150); and under the condition that no defect is detected on the printed substrate (150), moving (330) the printed substrate (150) along the common axis (160) from the inspection station (130) for further processing.
  14. The method according to claim 13, wherein: the substrate (150) is configured for providing a plurality of micro LEDs for specifically illuminating a location of the substrate (150); and a selection of the plurality of micro LEDs comprises a pixel of a display.
  15. The method according to claim 13 or 14, wherein: the print station (120) is configured for selectively printing an ink onto a plurality of locations on the substrate (150); and the ink is configured for forming, when illuminated by a micro LED, a component of a pixel of a display device.

Description

TECHNICAL FIELD Embodiments of the present invention relate to an apparatus and method for printing on a substrate for display manufacture, particularly a substrate for the manufacture of micro LED-based displays, particularly displays including quantum dot-based dyes. Embodiments of the present invention particularly relate to an apparatus and a method to perform a printing operation and a reworking operation on a substrate along a common axis. Further embodiments relate to an apparatus having a print head and a print bar for printing on a substrate for display manufacture. BACKGROUND In display manufacture, several techniques are known to provide displays with improved resolution and contrast characteristics, and many approaches have been developed. Where LCDs (liquid crystal displays) use light-modulating properties of liquid crystals for influencing light provided by a backlight source or reflector to produce images in color or monochrome, the technique of OLED (organic light-emitting diode) displays provides organic materials directly emitting visible light in response to an electric power. OLED displays are known to have beneficial effects in contrast to LCDs, for example, thinner and lighter displays can be provided, the OLED displays achieve deeper black levels and a higher contrast ratio as well as are flexible and transparent, thus allowing the use of OLED displays in multiple applications such as screens, TVs, smartphones, etc. The generation of OLED substrates is typically carried out by coating an organic material onto a substrate, the organic material providing the primary colors red, blue and green to generate pixels on the substrate. The coating processes can be, e.g., based on the evaporation of organic materials, e.g., a host material and dopant materials, being deposited on the substrate, to provide for the differently colored pixels on the substrate. In contrast to the OLED technology, micro LEDs (light-emitting diodes) can provide microscopically small pixels on a substrate, the micro LEDs being made of inorganic materials, e.g., indium gallium nitride (InGaN), provided as semiconductor arrays, the micro LEDs being capable of self-emitting light in response to an electric power. The micro LED technology can be beneficial compared to the OLED technology regarding display manufacture as regards to, e.g., lifetime, brightness and contrast of the resulting displays. So far, the manufacture of micro LED arrays suitable for display manufacture has been expensive and inefficient. Furthermore, the provision of colored pixels is challenging. An approach to providing colored pixels in micro LED based displays is the use of fluorescent dyes which are excited by light emitted from a micro LED and as a result emit a specific radiation pattern, such as a band of wavelengths corresponding to the colors red, green and blue. Quantum dot dyes can be suitable for this purpose. The dyes are typically applied to specific locations of the substrate corresponding to the location of a micro LED by a printing process. A suitable printing process for providing the dyes onto a substrate can be a limiting factor in achieving a cost and time effective manufacturing of high-quality displays. Document US 2003/189604 A1 describes a device for fabricating a display panel having ink-jet printing applied thereto, including a stage for supporting a substrate, a base having one or more than one rail for transporting the stage, and one or more than one ink-jet head rotatable by an angel for spraying a pattern forming solution to the substrate. Document US 2013/177698 A1 describes a method for inspection aided printing. The method includes printing, by a printing unit of a system, a pattern on an area of a substrate, during a printing process, inspecting, by an inspection unit of the system, the area to provide inspection results, and searching, by a processor of the system, for a defect, based upon the inspection results. In light of the above, it is beneficial to provide an improved apparatus or method for printing on substrates for display manufacture. SUMMARY The invention is set out in the appended set of claims. According to an aspect, an apparatus for printing on a substrate for display manufacture is provided. The apparatus includes an alignment station for aligning the substrate, a print station for printing on the substrate and an inspection station for inspecting the printed substrate for defects. The alignment station, the print station and the inspection station are provided along a common axis. The common axis is configured for moving the substrate from the alignment station to the print station and from the print station to the inspection station. The common axis is further configured for moving the printed substrate, under the condition that a defect is detected in the inspection station, from the inspection station back to the print station, the print station being configured for reworking the printed substr