Prior art — US Patent 9516909

To identify the most relevant prior art for US patent 9516909, I will examine the "Cited By" and "Citations" sections of the patent document itself. These sections list the patents and non-patent literature that the examiner considered relevant during prosecution, and also patents that have subsequently cited US9516909. For this task, I will focus on the "Citations" section, as these are the prior art references that were explicitly considered during the examination of US9516909.

Here's an analysis of the prior art cited in US Patent 9516909, along with a brief description and potential anticipation for each. It's important to note that a full anticipation analysis would typically require a detailed claim construction and comparison, but I'll provide a high-level assessment based on the descriptions.

The patent document for US9516909B2 lists the following "Citations" (prior art references cited by the examiner):

1. US3946441A

Full Citation: US3946441A, Johnson John R., "Safety helmet", published March 30, 1976.
Description: This patent describes a safety helmet. The details provided in the US9516909 document's abstract for this reference are limited.
Potential Anticipation: Without further description of US3946441A's specific mechanisms, it's difficult to pinpoint direct anticipation. However, as a general "safety helmet," it likely addresses basic protective shell and lining concepts, potentially anticipating aspects of claims 1 and 12 related to having an outer protective shell/layer and a liner layer.

2. US4352484A

Full Citation: US4352484A, Energy Absorption Systems, Inc., "Shear action and compression energy absorber", published October 5, 1982.
Description: This patent describes a shear action and compression energy absorber.
Potential Anticipation: This reference directly addresses "shear action" and "compression energy absorption," which are key functions of the "first energy transformer layer associated with a shear mechanism" in claims 1 and 12 of US9516909. Depending on the specific implementation described in US4352484A, it could potentially anticipate the shear mechanism allowing relative sliding, or the function of absorbing impact forces, for claims 1 and 12.

3. US5713082A

Full Citation: US5713082A, A.V.E., "Sports helmet", published February 3, 1998.
Description: This patent describes a sports helmet.
Potential Anticipation: Similar to US3946441A, as a general "sports helmet," it likely covers fundamental helmet structures (shells, liners). It could potentially anticipate the broader elements of claims 1 and 12, such as an outer protective shell/layer, an inner protective shell/layer, and a liner layer.

4. US5815846A

Full Citation: US5815846A, Tecno-Fluidos, S.L., "Resistant helmet assembly", published October 6, 1998.
Description: US9516909 provides a summary of this patent: "An impact resistant helmet assembly having a first material layer coupled to a second material layer so as to define a gas chamber therebetween which contains a quantity that provides impact dampening upon an impact force being applied to the helmet assembly. The helmet assembly further includes a containment layer disposed over the second material layer and structured to define a fluid chamber in which a quantity of fluid is disposed. The fluid includes a generally viscous gel structured to provide some resistance against disbursement from an impacted region of the fluid chamber to non-impacted regions of the fluid chamber, thereby further enhance the impact distribution and dampening of the impact force provided by the helmet assembly.”
Potential Anticipation: This reference is highly relevant as it describes a multi-layer helmet with fluid chambers for impact dampening and distribution, specifically mentioning a viscous gel for resistance against disbursement. This directly addresses the concept of an "energy transformer layer" and potentially the use of "gels" or "fluids" as part of the shear mechanism as described in claims 1 and 12 of US9516909, and the associated dependent claims that specify such materials (e.g., "first absorptive/dissipative material"). The fluid/gel layer could potentially allow for relative movement, thus anticipating aspects of the shear mechanism.

5. US6103641A

Full Citation: US6103641A, Gehring Textiles Inc, "Blunt trauma reduction fabric for body armor", published August 15, 2000.
Description: This patent describes a blunt trauma reduction fabric for body armor.
Potential Anticipation: While not a helmet, this reference discusses blunt trauma reduction, which is a general protective function. If the fabric described has properties that could be adapted for use in a helmet's energy transformer layer, particularly for impact absorption or dissipation, it could potentially anticipate certain material aspects of the energy transformer layers in claims 1 and 12, especially those related to absorptive/dissipative materials (e.g., dependent claim 2 or 13).

6. WO2001045526A1

Full Citation: WO2001045526A1, Neuroprevention Scandinavia Ab, "Protective helmet", published June 28, 2001.
Description: This patent describes a protective helmet.
Potential Anticipation: Similar to other general helmet patents, this reference could anticipate the basic structural elements of claims 1 and 12 (outer/inner shells/layers, liner). More specific details from the WO publication would be needed for a deeper analysis of anticipation of the shear mechanism.

7. US5956777A

Full Citation: US5956777A, Grand Slam Cards, "Helmet", published September 28, 1999.
Description: US9516909 provides a summary of this patent: "A helmet for protecting a head by laterally displacing impact forces, said helmet comprising: a rigid inner shell formed as a single unit; a resilient spacing layer disposed outside of and in contact with said inner shell; and an articulated shell having a plurality of discrete rigid segments disposed outside of and in contact with said resilient spacing layer and a plurality of resilient members which couple adjacent ones of said rigid segments to one another.”
Potential Anticipation: This reference is highly relevant as it describes a helmet with an "articulated shell having a plurality of discrete rigid segments" and a "resilient spacing layer." The concept of "laterally displacing impact forces" and the articulated/segmented outer shell suggests a mechanism for relative movement or force redirection, which could directly anticipate aspects of the shear mechanism in claims 1 and 12 allowing the outer shell/layer to slide relative to the inner.

8. US6145348A

Full Citation: US6145348A, Tietex International, Inc., "Fabric and process and apparatus for producing same", published November 14, 2000.
Description: This patent describes a fabric and a process/apparatus for producing it.
Potential Anticipation: This reference appears to be more focused on material manufacturing. Without specific details on the fabric's properties relating to impact absorption, shear reduction, or its use in a multi-layered protective gear, direct anticipation of the core claims of US9516909 is less apparent. However, it could potentially anticipate materials used in the layers if the fabric is suitable for such applications.

9. US6434755B1

Full Citation: US6434755B1, Southern Impact Research Center, Llc, "Helmet", published August 20, 2002.
Description: US9516909 provides a summary of this patent: "a football helmet with liner sections of different thicknesses and densities. The thicker, softer sections would handle less intense impacts, crushing down until the thinner, harder sections take over to prevent bottoming out.”
Potential Anticipation: This patent describes a helmet with liner sections of varying thicknesses and densities for impact management. While it focuses on "liner sections" rather than a separate outer/inner shell sliding mechanism, the concept of managing impacts through varied material properties in layers could be broadly relevant to the energy transformer layers of US9516909. It might anticipate the idea of different materials or structures within a layer for impact absorption (e.g., dependent claim 2 or 13 if the "absorptive/dissipative material" includes varying densities).

10. US6658671B1

Full Citation: US6658671B1, Neuroprevention Scandinavia Ab, "Protective helmet", published December 9, 2003.
Description: This patent describes a protective helmet.
Potential Anticipation: Similar to other general helmet patents, this reference could anticipate the basic structural elements of claims 1 and 12 (outer/inner shells/layers, liner). More specific details from the patent would be needed for a deeper analysis of anticipation of the shear mechanism.

11. US20030088906A1

Full Citation: US20030088906A1, Baker Gregg S., "Head stabilizing system", published May 15, 2003.
Description: This patent describes a head stabilizing system.
Potential Anticipation: "Head stabilizing" suggests mechanisms that might limit movement or absorb forces, which could be broadly related to the function of protective gear. Depending on the specific mechanisms used for stabilization, it could potentially anticipate elements of the energy transformer layers or the overall securing function of the helmet in claims 1 and 12.

12. US6378140B1

Full Citation: US6378140B1, Carl J. Abraham, "Impact and energy absorbing product for helmets and protective gear", published April 30, 2002.
Description: This patent describes an impact and energy absorbing product for helmets and protective gear.
Potential Anticipation: This reference is directly relevant to "impact and energy absorbing" elements in protective gear. It could potentially anticipate the "first energy transformer layer" and its function of absorbing impact forces as described in claims 1 and 12. The specific mechanisms for energy absorption would determine if it anticipates the shear mechanism for relative sliding.

13. US20040126565A1

Full Citation: US20040126565A1, Ganapathy Naganathan, "Actively controlled impact elements", published July 1, 2004.
Description: This patent describes actively controlled impact elements.
Potential Anticipation: The concept of "actively controlled impact elements" could potentially anticipate some of the advanced features mentioned in the description of US9516909 for the energy and impact transformer layers, such as "electro-rheological elements" or "magneto-rheological elements" (though these specific elements are not explicitly claimed in claims 1 or 12, they are discussed in the patent's description as possible implementations). If the active control allows for a change in viscosity or similar properties that enable relative sliding upon impact, it could anticipate aspects of the shear mechanism.

14. US6996856B2

Full Citation: US6996856B2, Puchalski Ione G, "Protective head covering having impact absorbing crumple zone", published February 14, 2006.
Description: This patent describes a protective head covering having an impact absorbing crumple zone.
Potential Anticipation: The term "impact absorbing crumple zone" strongly suggests a mechanism for dissipating energy upon impact. This could anticipate the energy absorption aspect of the "first energy transformer layer" in claims 1 and 12. The "crumple" action might also involve deformation or relative movement that could be seen as anticipating aspects of the shear mechanism.

15. US7076811B2

Full Citation: US7076811B2, Puchalski Ione G, "Protective head covering having impact absorbing crumple or shear zone", published July 18, 2006.
Description: US9516909 provides a summary of this patent: "The shell consists of three (or more) discrete panels that are physically and firmly coupled together providing rigid protection under most circumstances, but upon impact the panels move relative to one another, but not relative to the user's head, thereby permitting impact forces to be dissipated and/or redirected away from the cranium and brain within. Upon impact to the helmet, there are sequential stages of movement of the panels relative to each other, these movements initially being recoverable, but with sufficient vector forces the helmet undergoes structural changes in a pre-determined fashion, so that the recoverable and permanent movements cumulatively provide a protective ‘crumple zone’ or ‘shear zone’.”
Potential Anticipation: This patent is highly relevant and likely a very strong piece of prior art. It explicitly describes a multi-panel shell where panels "move relative to one another" upon impact to dissipate forces and create a "shear zone." This directly anticipates the "outer protective shell" and "inner protective shell" (or layers), and critically, the "first energy transformer layer associated with a shear mechanism, wherein the shear mechanism allows the outer protective shell to slide relative to the inner protective shell" as defined in claims 1 and 12 of US9516909. The description of recoverable and permanent movements for energy dissipation also aligns with the function of the energy transformer. This reference could anticipate claims 1 and 12 entirely, and also dependent claims describing the nature of the shear mechanism (e.g., if the panel movement acts like conical structures, truss-like structures, etc.).

16. WO2004032659A1

Full Citation: WO2004032659A1, Madey Steven M, "Head protective devices", published April 22, 2004.
Description: This patent describes head protective devices.
Potential Anticipation: As a general "head protective device," this could broadly anticipate the structural elements of a helmet in claims 1 and 12. Specifics would be needed to determine if it anticipates the shear mechanism.

17. US7254843B2

Full Citation: US7254843B2, Srikrishna Talluri, "Impact absorbing, modular helmet", published August 14, 2007.
Description: This patent describes an impact absorbing, modular helmet.
Potential Anticipation: "Impact absorbing" directly relates to the function of the "first energy transformer layer" in claims 1 and 12. The "modular" aspect might suggest separable components that could be construed as layers. Specifics of the impact absorbing mechanism would be crucial to determine anticipation of the shear mechanism.

18. US20080066217A1

Full Citation: US20080066217A1, Bart Depreitere, "Protective Helmet", published March 20, 2008.
Description: This patent describes a protective helmet.
Potential Anticipation: Similar to other general helmet patents, this reference could anticipate the basic structural elements of claims 1 and 12 (outer/inner shells/layers, liner). More specific details from the patent would be needed for a deeper analysis of anticipation of the shear mechanism.

19. US20060059605A1

Full Citation: US20060059605A1, Xenith Athletics, Inc., "Layered construction of protective headgear with one or more compressible layers of thermoplastic elastomer material", published March 23, 2006.
Description: This patent describes a layered construction of protective headgear with one or more compressible layers of thermoplastic elastomer material.
Potential Anticipation: This reference is highly relevant as it explicitly describes "layered construction of protective headgear" with "compressible layers." The term "compressible layers" indicates an energy-absorbing function. While it doesn't explicitly state "sliding" for shear reduction, if the compressible layers allow for some form of relative movement or deformation that dissipates shear forces, it could anticipate aspects of the "first energy transformer layer" in claims 1 and 12 and the use of absorptive/dissipative materials (dependent claims).

20. US20110004980A1

Full Citation: US20110004980A1, Leatt Brace Holdings (Pty) Limited, "Helmet", published January 13, 2011.
Description: This patent describes a helmet.
Potential Anticipation: Similar to other general helmet patents, this reference could anticipate the basic structural elements of claims 1 and 12 (outer/inner shells/layers, liner). More specific details from the patent would be needed for a deeper analysis of anticipation of the shear mechanism.

21. US8176574B2

Full Citation: US8176574B2, Voz Corp Pty Ltd, "Protective helmet", published May 15, 2012.
Description: This patent describes a protective helmet.
Potential Anticipation: Similar to other general helmet patents, this reference could anticipate the basic structural elements of claims 1 and 12 (outer/inner shells/layers, liner). More specific details from the patent would be needed for a deeper analysis of anticipation of the shear mechanism.

22. US8533869B1

Full Citation: US8533869B1, Noggin Group LLC, "Energy absorbing helmet underwear", published September 17, 2013.
Description: This patent describes energy absorbing helmet underwear.
Potential Anticipation: While it describes "helmet underwear" rather than the helmet itself, the concept of "energy absorbing" material is relevant to the "first energy transformer layer" in claims 1 and 12. Depending on the construction and placement of this "underwear," it could potentially anticipate the liner layer or the absorptive/dissipative materials within the transformer layers.

23. US8104593B2

Full Citation: US8104593B2, Keng-Hsien Lin, "Resilient shock-absorbing device", published January 31, 2012.
Description: This patent describes a resilient shock-absorbing device.
Potential Anticipation: "Resilient shock-absorbing device" directly relates to the function of the "first energy transformer layer" in claims 1 and 12. The specific construction of this device would determine if it anticipates the shear mechanism for relative sliding or the specific types of structures mentioned in dependent claims (e.g., conical, truss-like).

24. SE1050905A1 / WO2011087435A1

Full Citation: SE1050905A1, Mips Ab, "Intermediate layers of friction-reducing material", published July 14, 2011. (This appears to be the national phase equivalent of WO2011087435A1).
Full Citation: WO2011087435A1, Mips Ab, "Intermediate layer of friction decreasing material", published July 21, 2011.
Description: These patents describe intermediate layers of friction-reducing or friction-decreasing material.
Potential Anticipation: These references are highly relevant. The concept of "intermediate layers of friction-reducing material" or "friction decreasing material" directly anticipates the core mechanism of the "shear mechanism" that "allows the outer protective shell to slide relative to the inner protective shell" as claimed in claims 1 and 12 of US9516909. The purpose of such friction-reducing layers is explicitly to allow relative movement between helmet components to reduce rotational forces, which is a primary objective of US9516909. This could anticipate claims 1 and 12 entirely, and potentially dependent claims related to the nature of the absorptive/dissipative material if the friction-reducing material also serves that purpose.

25. US20130239397A1

Full Citation: US20130239397A1, Centre De Recherche Industrielle Du Quebec, "Apparatus and Method for Inserting a Component Through the Surface of a Workpiece", published September 19, 2013.
Description: This patent describes an apparatus and method for inserting a component through the surface of a workpiece.
Potential Anticipation: This reference appears to relate to manufacturing processes rather than the protective helmet structure itself. It is unlikely to anticipate any of the structural or functional claims of US9516909 directly.

26. WO2012109381A1

Full Citation: WO2012109381A1, Innovation Dynamics LLC, "Helmet omnidirectional energy management systems", published August 16, 2012.
Description: This patent describes helmet omnidirectional energy management systems.
Potential Anticipation: "Omnidirectional energy management systems" strongly suggests mechanisms for handling forces from various directions, including rotational and shear forces. This could anticipate the function of the "first energy transformer layer" in claims 1 and 12 to absorb impact, rotational, and shear forces, and potentially the mechanism allowing relative sliding.

27. US20130019384A1

Full Citation: US20130019384A1, Brainguard Technologies, Inc., "Biomechanics aware protective gear", published January 24, 2013.
Description: This patent describes biomechanics aware protective gear.
Potential Anticipation: This is a related patent application from the same assignee (Brainguard Technologies, Inc.) and shares a similar title, indicating it's part of the same patent family and likely discloses very similar or foundational concepts. It is explicitly listed as a priority document for US9516909. Therefore, it would likely anticipate the core concepts of claims 1-20 if its publication predates the critical date of US9516909 (which it does, as US9516909 claims priority to it). This reference would be highly relevant for anticipating all claims.

28. WO2013013180A1

Full Citation: WO2013013180A1, Robert Knight, "Biomechanics aware protective gear", published January 24, 2013.
Description: This patent describes biomechanics aware protective gear.
Potential Anticipation: This is another related patent application by the inventor (Robert Knight) and shares a similar title, also listed as a priority document. Similar to US20130019384A1, this reference would be highly relevant for anticipating all claims of US9516909 due to its familial relationship and earlier publication/priority.

29. EP2734071A1

Full Citation: EP2734071A1, Brainguard Technologies, Inc., "Biomechanics aware protective gear", published May 28, 2014.
Description: This patent describes biomechanics aware protective gear.
Potential Anticipation: Another related patent from the same assignee, sharing a similar title, and part of the same patent family. This would be highly relevant for anticipating claims 1-20.

30. US8863319B2

Full Citation: US8863319B2, Brainguard Technologies, Inc., "Biomechanics aware protective gear", published October 21, 2014.
Description: This patent describes biomechanics aware protective gear. US9516909 explicitly states it claims priority to US application Ser. No. 13/554,471, entitled BIOMECHANICS AWARE PROTECTIVE GEAR, filed Jul. 20, 2012, now issued as U.S. Pat. No. 8,863,319.
Potential Anticipation: This is the direct parent patent to US9516909, meaning US9516909 is a continuation of an application that matured into US8863319B2. Therefore, US8863319B2 would disclose substantially the same subject matter and would anticipate all claims of US9516909 under 35 U.S.C. § 102.

31. US20150000014A1

Full Citation: US20150000014A1, Brainguard Technologies, Inc., "Biomechanics aware helmet", published January 1, 2015.
Description: This patent describes a biomechanics aware helmet.
Potential Anticipation: Another related application from the same assignee, sharing a similar title, and part of the same patent family. This would be highly relevant for anticipating claims 1-20.

32. US9060561B2

Full Citation: US9060561B2, Brainguard Technologies, Inc., "Biomechanics aware helmet", published June 23, 2015.
Description: This patent describes a biomechanics aware helmet. US9516909 explicitly states it claims priority to US application Ser. No. 14/485,993, entitled BIOMECHANICS AWARE HELMET, filed Sep. 15, 2014, now issued as U.S. Pat. No. 9,060,561.
Potential Anticipation: This is another direct parent patent to US9516909, meaning US9516909 is a continuation of an application that matured into US9060561B2. Therefore, US9060561B2 would disclose substantially the same subject matter and would anticipate all claims of US9516909 under 35 U.S.C. § 102.

33. US20150245681A1

Full Citation: US20150245681A1, Brainguard Technologies, Inc., "Biomechanics aware protective gear", published September 3, 2015.
Description: This patent describes biomechanics aware protective gear.
Potential Anticipation: Another related application from the same assignee, sharing a similar title, and part of the same patent family. This would be highly relevant for anticipating claims 1-20.

34. US9271536B2

Full Citation: US9271536B2, Brainguard Technologies, Inc., "Biomechanics aware protective gear", published March 1, 2016.
Description: This patent describes biomechanics aware protective gear. US9516909 explicitly states it claims priority to US application Ser. No. 14/714,093, entitled BIOMECHANICS AWARE PROTECTIVE GEAR, filed May 15, 2015, now issued as U.S. Pat. No. 9,271,536.
Potential Anticipation: This is another direct parent patent to US9516909, meaning US9516909 is a continuation of an application that matured into US9271536B2. Therefore, US9271536B2 would disclose substantially the same subject matter and would anticipate all claims of US9516909 under 35 U.S.C. § 102.

35. DE102011086791A1

Full Citation: DE102011086791A1, Continental Automotive Gmbh, "Closing method for closing bore of workpiece using bore closing device, involves placing bore in workpiece, where bore in area of workpiece near to surface has bigger diameter than in area of workpiece away from surface", published May 23, 2013.
Description: This patent describes a closing method for a bore of a workpiece.
Potential Anticipation: This reference appears to be entirely unrelated to protective helmets or energy absorption. It is highly unlikely to anticipate any claims of US9516909.

Summary of Most Relevant Prior Art:

Based on the descriptions, the most relevant prior art references that explicitly or strongly suggest anticipation of the core claims of US9516909 (specifically claims 1 and 12 regarding a shear mechanism allowing relative sliding between helmet layers) are:

US7076811B2 (Puchalski): Explicitly describes a multi-panel shell where panels "move relative to one another" to create a "shear zone" for dissipating impact forces. This directly addresses the fundamental concept of relative sliding for shear reduction.
US5956777A (Popovich): Describes an "articulated shell having a plurality of discrete rigid segments" and a "resilient spacing layer" for "laterally displacing impact forces." This also suggests mechanisms for relative movement to manage forces.
US5815846A (Calonge): Describes a multi-layer helmet with fluid chambers containing viscous gel for impact dampening and distribution, which could facilitate relative movement between layers.
SE1050905A1 / WO2011087435A1 (Mips Ab): Describes "intermediate layers of friction-reducing material" to allow relative movement and reduce rotational forces. This is a very strong antecedent for the shear mechanism allowing relative sliding.
US20060059605A1 (Xenith Athletics, Inc.): Describes "layered construction of protective headgear with one or more compressible layers" which, depending on their nature, could contribute to relative movement or shear force dissipation.
US8863319B2, US9060561B2, US9271536B2, US20130019384A1, WO2013013180A1, EP2734071A1, US20150000014A1, US20150245681A1: These are all continuation applications or parent patents within the same patent family as US9516909. They would inherently anticipate the subject matter of US9516909 as they disclose substantially the same invention, building upon earlier priority dates.