Prosecution Insights
Last updated: April 19, 2026
Application No. 18/096,875

CANDLE FILTER ELEMENT

Non-Final OA §103§112
Filed
Jan 13, 2023
Examiner
HE, QIANPING
Art Unit
1776
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Lenzing Aktiengesellschaft
OA Round
3 (Non-Final)
68%
Grant Probability
Favorable
3-4
OA Rounds
3y 2m
To Grant
80%
With Interview

Examiner Intelligence

Grants 68% — above average
68%
Career Allow Rate
169 granted / 248 resolved
+3.1% vs TC avg
Moderate +12% lift
Without
With
+11.7%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
62 currently pending
Career history
310
Total Applications
across all art units

Statute-Specific Performance

§101
1.4%
-38.6% vs TC avg
§103
43.2%
+3.2% vs TC avg
§102
17.6%
-22.4% vs TC avg
§112
34.0%
-6.0% vs TC avg
Black line = Tech Center average estimate • Based on career data from 248 resolved cases

Office Action

§103 §112
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Rejections - 35 USC § 112(b) The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claims 1 and 3–13 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. The limitation of “non-negligible” in claim 1 is indefinite because the instant disclosure does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. MPEP 2173.05(b)(III)(D). Claims 3–13 are indefinite because they depend on claim 1. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. The claims are rejected as follows: Claims 1 and 3–13 are rejected under 35 U.S.C. 103 as being obvious over Barrett, US 2,057,814 A (“Barrett”) in view of Wagner et al., EP 3,444,018 A1 (“Wagner”)1. Regarding claim 1: Barrett discloses that a filter element (Barrett’s filter tube A) comprising a support body (Barrett’s body portion 1 and the plurality of arcuate elements 4) and a filter cloth (Barrett’s fabric covering 7B, Barrett, Figs. 1–2, p. 2, ll. 36–44 and ll. 68–71), the filter cloth 7 being laid around the support body 1, 4 (Barrett discloses its fabric covering 7 is drawn to a tight condition in contact with the outer faces of the ridges between the grooves 5 of the arcuate element 4, Barrett Fig. 2, p. 2, ll. 71–75), the support body 1, 4 comprises a dip channel that is centrally positioned (Barrett’s central passage 2) and outer longitudinal flow channels (Barrett’s grooves 5, Barrett Fig. 2, p. 2, ll. 36–40 and ll. 43–58), Barrett discloses that the support body 1, 4 is formed of a continuous profile (Barrett disclose its support body 1 and 4 forms a continuous profile because there are no gaps in between, Barrett Fig. 2, p. 2, ll. 43–44), Barrett also discloses that the outer longitudinal flow channels 5 are open radially towards an outside of the filter element (as best shown in Fig. 2, Barrett Fig. 2), the filter cloth takes a backwashing position and a filtration position, the filtration position having a non-negligible volume difference from the backwashing position (noted here that this limitation describes intended use, and Barrett’s filter cloth is capable to move in response to the flow direction, i.e., in the filtration position, fluid flows from an outer circumference of the filter cloth and causing the filter cloth to move slightly inward, and in the backwashing position, the fluid comes from inside and causing the filter cloth to move slightly outward, which represents the non-negligible volume difference between the filtration and backwashing position, the limitation of “non-negligible” is interpreted as a different that can be detected since the instant disclosure does not provide a degree for the term “non-negligible”, Barrett Fig. 2). Barrett does not disclose that the support body 1, 4 is formed of a continuous extruded profile. Barrett does not disclose that the support body comprises a thermoplastic material, a ceramic material or a metal. In the analogous art of filter bag supporting systems, Wagner discloses a support body (Wagner’s support basket 6, Wagner Fig. 2, p. 3) inserted inside a filter bag 5 to support the filter bag 5, Wagner Fig. 2, p. 3. Wagner discloses its support basket is made of thermoplastic, Wagner p. 2. Wagner also discloses that its support body is an endless plastic extruded profile, Wagner Fig. 2, p. 1. Wagner discloses its support body made of plastic has the advantages of simplicity, flexibility, reduced weight, corrosion resistance, and cost reduction, and can be customized in design, Wagner p. 1. Wagner also discloses that a thermoplastic material is advantageous in particular by extrusion processable, with inherent flame resistance and excellent electrical properties, and impermeable to most liquids and gases and suitable for complex geometries, Wanger p. 2. It would therefore have been obvious for one ordinary skill in the art at the time of filing to modify Barrett’s support body 1, 4 to be made of Wagner’s thermoplastic with extrusion for the benefits disclosed. Note that at the time of Wagner’s invention, polymer/plastic technique has not been advanced as much to allow simple and integral processing, and a person of ordinary skill in the art would be motivated to use Wagner’s thermoplastic material and extrusion processing when those options become available. Regarding claim 3: Modified Barrett discloses that the filter element according to claim 1, wherein an outer contour of the support body is circular, star-shaped, cricket bat-shaped or elliptical (Barrett’s outer contour of the support body 1, 4 is star-shaped due to the plurality of grooves 5 provided at the outer surface of arcuate element 4). Barrett Fig. 2, p. 2, ll. 45–47. Regarding claim 4: Modified Barrett discloses that the filter element according to claim 1, wherein a central tube forms the dip channel (Barrett’s dip channel 2 is formed by a tubular body portion as shown in Fig. 1), and wherein longitudinal bars are mounted on the central tube (Barrett’s longitudinal ridges 5’ would read on the claimed” longitudinal bars” and they are mounted to the central tube because it is part of the arcuate member 4, which is secured to the body portion 1). Barrett Figs. 1 and 4, p. 2, ll. 43–44 and ll. 11–20 (2nd column). Regarding claim 5: Modified Barrett discloses that the filter element according to claim 1, wherein an outer longitudinal flow channel (one of Barrett’s grooves 5) is formed by a longitudinal wall (Barrett’s ridges 5’) within a material forming the support body (Barrett’s grooves 5 are defined by Barrett’s ridges 5 and both are part of Barrett’s arcuate element 4, and therefore they are formed of the same material of the claimed support body) with rounded outer edges (Barrett’s ridges 5 are rounded to accommodate the filter fabric 7 as best shown in Barrett’s Fig. 2) and being covered by the filter cloth 7. Barrett Fig. 2, p. 2, ll. 11–20. Regarding claim 6: It is noted that the published specification (hereinafter “Spec.”) teaches that the total differential volume shall mean the total volume (accessible for the filtrate) in the filter cloth in backwashing position minus the volume (accessible for the filtrate) of the channels covered by the filter cloth in the filtration position. Spec. [0044]. The examiner is interpreting the term “total differential volume” accordingly, where the “total differential volume” depends on the volume different of the outer longitudinal flow channels in backwash and filtration position. Modified Barrett does not explicitly disclose that the filter element according to claim 1, wherein a volume of the dip channel 2 is at least 1% larger than a total differential volume of all outer longitudinal flow channels. However, Barrett discloses that its central longitudinal passageway 2 is in direct communication with the longitudinal circumferential grooves 5, Barrett Fig. 3, p. 2, ll. 32–38. It is therefore understood that the flow volume in dip channel 2 flows into/out of all the longitudinal circumferential grooves 5, It would therefore have been obvious for one ordinary skill in the art at the time of filing for the volume of the dip channel 2 to be at least 1% larger than a total differential volume of all outer longitudinal flow channels because it has to has the capability to accommodate all the flow from all the longitudinal circumferential grooves 5 regardless of its filtration and backwash position. Additionally, the instant disclosure does not teach the claimed range is critical to the operation of the claimed invention. Therefore, absent evidence of criticality, this difference fails to patentably distinguish over prior art because it produces a difference in degree rather than in kind. MPEP 2044.05 (III)(A). Regarding claim 7: Modified Barrett discloses that the filter element according to claim 1, wherein the filter cloth is fixed on the filter element by cloth-fixing elements (Barrett’s elements 7’), one cloth-fixing element on a bottom end of a longitudinal channel area and one cloth-fixing element on a top end of the longitudinal channel area of the filter element (Barrett’s elements 7’ comprising two elements with one located on a top end and the other located on a bottom end of the fabric covering 7’ and thus aid in securing the fabric covering in place). Barrett Fig. 1, p. 2, ll. 58–64 (2nd column). While Barrett does not explicitly disclose that the cloth-fixing elements 7 seal the filtrate room against the feed room, Barrett’s element 7’ necessarily need to provide a seal function to prevent unfiltered fluid bypass the fabric covering 7 and enter grooves 5. Regarding claim 8: Modified Barrett discloses that the filter element according to claim 1, wherein the filter element further comprises a coupling part (portion of Barrett’s head 9 proximate Barrett’s inclined upper face 9a) located between the support body 1 and a fixing device (Barrett’s elements 7’) and a pin (Barrett’s pin 1a) for alignment of the filter element A (intended use, and Barrett’s pin 1a is capable of aligning the filter element A with Barrett’s head 9, which is part of the filter element because Barrett’s pin 1a passing through a portion of head 9 and into body portion 1, and therefore align those two parts) in a filter device (device as shown in Barrett’s Fig. 1). Barrett Fig. 1, p. 2, ll. 31–38 (2nd column). Regarding claim 9: Modified Barrett discloses that the filter element according to claim 8, wherein the filter cloth is fixed above the coupling part to cover the pin and the coupling part (as best shown in Barrett’s Fig. 3, Barrett’s fabric covering 7 covers the coupling part and pin 1a). Barrett Fig. 3, p. 2, ll. 31–38 (2nd column). Regarding claim 10: Modified Barrett discloses that the filter element according to claim 15, wherein the thermoplastic material is a compound material containing stability-enhancing additives including carbon fibers or glass fibers (Wagner discloses its thermoplastic material is fiber-reinforced with suitable fibers being glass fibers and/or carbon fibers, Wagner p. 2). Regarding claim 11: Modified Barrett discloses that a filter device comprising one or more filter elements, each of the one or more filter element being configured as the filter element of claim 1, wherein the filter device (as shown in Fig. 1) is a vessel (because Barrett’s filter device is a hollow container) in which unfiltered fluid (located outside of fabric covering 7) is separated from filtered fluid (inside fabric covering 7) by a head plate (Barrett’s head 12, which is shown as a flat disc and therefore would read on the claimed plate, and Barrett’s head 12 covers top of Barrett’s fabric covering 7 and therefore isolates external unfiltered fluid from internal filtered plate). Barrett Fig. 1, p. 2, ll. 39–43 (2nd column). Regarding claim 12: Modified Barrett discloses that the filter device of claim 11, wherein the one or more of the filter elements are mounted on one or more common filtrate headers (Barrett’s flanged conductor 15) as collector tubes (Barrett’s flanged conductor 15 would read on the collector tubes because they are tube shaped and are configured to collect filtered fluid). Barrett Fig. 1, p. 2, ll. 50–57 (2nd column). Regarding claim 13: Modified Barrett discloses that the filter element of claim 1, wherein the filter element is used in a system configuration where one or more of the filter elements are mounted on tube headers (Barrett’s flanged conductor 15) and are submerged in a feed contained in an open basin (Barrett discloses its tube filter is suspended in the liquid or semiliquid contained within the receptacle or suitable tank, the receptable or suitable tank would read on the claimed “open basin) and wherein a differential pressure needed to drive filtration is created by a vacuum inside the tube headers (Barrett discloses its flanged conductor 15 is connected to means for creating vacuum within the passage 2 and grooves 5 and means for forcing air through said passageway 2 and grooves 5). Barrett Fig. 1, p. 1, ll. 11–16 and p. 2, ll. 50–57. Response to Arguments Claim Rejections - 35 USC § 103 The applicant amends the claims to include a limitation originally from claim 14 with a further limitation of “non-negligible volume.” The applicant then transverse the rejection based on the amendment, the applicant argues that, neither Barrett or Lutz teaches the non-negligible volume and Lutz and Herrington do not align with the support body of claim 1, Applicant Rem. dated Feb. 12, 2026 (“Applicant Rem.”) p. 8–11. The examiner respectfully does not agree, the term “non-negligible” is not defined in the instant disclosure, it is unclear what standard is used to ascertain this term. The examiner is interpreting this term as a detectable difference, and since a filter cloth is a fabric that moves with the forced applied by the fluid, there would necessarily be a detectable volume difference between the filtration and backwashing position because the wire wound around does not cover the entirety of an outer surface of the filter cloth, which means the filter cloth exposed between adjacent wires will be able to take an inward or outward position based on a fluid flow direction. Additionally, the examiner points out that the current rejection depends on Wanger instead of Lutz or Herrington, applicant’s arguments regarding Lutz or Herrington are therefore moot. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to QIANPING HE whose telephone number is (571)272-8385. The examiner can normally be reached on 7:30-5:00 M-F. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jennifer Dieterle can be reached on (571) 270-7872. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see https://ppair-my.uspto.gov/pair/PrivatePair. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative or access to the automated information system, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /Qianping He/Examiner, Art Unit 1776 1 A copy of Wagner’s original document and machine translation are provided with the office action. The examiner relies on the original document for the text and machine translation for the figure.
Read full office action

Prosecution Timeline

Jan 13, 2023
Application Filed
Oct 30, 2023
Response after Non-Final Action
Apr 02, 2025
Non-Final Rejection — §103, §112
Aug 06, 2025
Response Filed
Sep 10, 2025
Final Rejection — §103, §112
Dec 10, 2025
Response after Non-Final Action
Feb 12, 2026
Request for Continued Examination
Feb 15, 2026
Response after Non-Final Action
Feb 19, 2026
Non-Final Rejection — §103, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
68%
Grant Probability
80%
With Interview (+11.7%)
3y 2m
Median Time to Grant
High
PTA Risk
Based on 248 resolved cases by this examiner. Grant probability derived from career allow rate.

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