Obviousness

Based on the information provided in the patent text, a detailed obviousness analysis under 35 U.S.C. § 103 can be constructed by identifying elements from the explicitly described "conventional systems" and "conventional large area displays" as prior art. While the patent text does not cite specific external patent documents or publications as prior art, it characterizes the state of the art that a person having ordinary skill in the art (PHOSITA) would have been aware of at the time of the invention.

The independent claims (Claim 1 for the system and Claim 7 for the method) center on an additive manufacturing system that uses multiple image projectors to create a composite image for curing resin, with specific digital filters applied to the sub-images.

Identified Prior Art Elements (from the patent's own description):

1. Conventional Additive Manufacturing Systems (e.g., DLP-based):

   • These systems "typically use digital light processing (DLP) or alike imaging in order to expose an entire layer at once with improved speed."
   • They involve a resin pool and a build area where resin is exposed to light to form solid polymer layers.
   • A known problem with these systems is that "as the layer size increases, the pixel size increases proportionally. The result is a decrease in the resolution of the final part, which will negatively affect part accuracy and surface finish. This also has the negative affect of reducing the projected energy density, which slows down the print process further."
   • These systems use light to cause resin to react, and "the reaction dynamics of the resin are much different (and less tolerant to deviations) than the response (and discrimination) of a human eye."

2. Conventional Large Area Display Systems (Multi-projector setups):

   • These systems "utilize composite images containing an array of sub-images projected from multiple image projectors."
   • They "employ filters to adjust the sub-images within the composite image."
   • These filters are used to manage aspects such as "warp correction filters that provide geometric correction, filters with edge blending bars at one or more sub-image edges, [and] irradiance mask filters that normalize irradiance." (While the patent describes these as filters used in its invention, it implies their existence or analogous functions in the context of large area displays that also "employ filters to adjust the sub-images.")
   • Such systems typically involve adjacent sub-images overlapping and using edge blending to create seamless transitions.

Obviousness Argument under 35 U.S.C. § 103:

Combination: A person having ordinary skill in the art (PHOSITA) in additive manufacturing, faced with the known problems of scaling conventional DLP additive manufacturing systems (i.e., decreased resolution and energy density with larger build areas), would have been motivated to combine the principles of conventional DLP additive manufacturing with the multi-projector array technology from conventional large area display systems.

Motivation to Combine:
The primary motivation for this combination would be to overcome the inherent limitations of single-projector DLP systems when attempting to increase the build area. By adopting the multi-projector approach common in large area displays, a PHOSITA could achieve a larger overall build area in additive manufacturing without sacrificing the pixel density (resolution) or projected energy density that is crucial for part accuracy, surface finish, and print speed. The multi-projector array allows for the "additive manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering," which is a primary classification of the patent (B29C64/00, B33Y10/00).

Adaptation and Obviousness of Specific Filters:

When adapting a multi-projector system from large area displays to additive manufacturing, a PHOSITA would find the inclusion and adaptation of the claimed filters obvious:

1. Warp Correction Filter (geometric correction), Irradiance Mask (normalizes irradiance), and Edge Blending Bar (at sub-image edges): These filters are explicitly described as being employed in "conventional large area displays" to adjust and seamlessly integrate multiple sub-images into a composite image. A PHOSITA, aiming to achieve a high-quality, uniform curing across a large build area in a 3D printer, would recognize the necessity of these techniques to correct for mechanical misalignments, optical distortions, and intensity variations inherent in multi-projector systems. Ensuring geometric accuracy, uniform light intensity, and seamless transitions (via edge blending in overlapping regions) are fundamental for producing accurate and structurally sound printed objects. Therefore, incorporating these known filters from the display art into an additive manufacturing system would be a routine design choice to achieve the desired functional outcome of a high-quality, large composite image.

2. Gamma Adjustment Mask (adjusts sub-image energy based on a reactivity of the resin): While conventional large area displays employ filters, the patent emphasizes a "substantial difference" between the requirements for large area displays (for human observers) and additive manufacturing systems (for resin reaction). The patent explicitly states that "PRPSs use light to cause resin to react, and the reaction dynamics of the resin are much different (and less tolerant to deviations) than the response (and discrimination) of a human eye." Given this critical understanding, a PHOSITA in additive manufacturing would immediately recognize that simply transferring display-oriented filters would be insufficient. The PHOSITA would know that accurate and consistent curing of photoreactive resins depends directly on the precise control of light energy according to the resin's specific reactivity characteristics. The concept of "gamma correction" is generally known in image processing to adjust the intensity response curve. Therefore, adapting this concept to create a "gamma adjustment mask that adjusts sub-image energy based on a reactivity of the resin" would be an obvious optimization. This adaptation directly addresses the known need to "map the irradiance range to the particular resin reactivity range" to "enable smoother and more accurate surfaces to be realized across different resins," and to account for varying resin compositions and curing times. The patent describes how "different resins have different reactivity ranges that require different irradiance and exposure times to achieve the same cure depth." Thus, a PHOSITA would be motivated to develop a mechanism, such as a gamma adjustment mask, to precisely control energy delivery to account for these material-specific properties, thereby enabling high-fidelity printing with various resins.

In conclusion, the combination of a conventional DLP additive manufacturing system with a multi-projector array from large area display systems would be obvious to a PHOSITA seeking to overcome scaling limitations. The subsequent adaptation of standard display filters (warp correction, irradiance mask, edge blending) for the additive manufacturing context, and the specific adaptation of a "gamma adjustment mask" to account for the known criticality of resin reactivity in 3D printing, would also be within the purview of a PHOSITA.