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 Interpretation
Claims 1-10 have been reviewed to determine whether any claim limitation invokes 35 U.S.C. 112(f). A claim limitation is presumed not to invoke 35 U.S.C. 112(f) unless it recites the term “means” (or a non-structural substitute for “means”) coupled with functional language, without reciting sufficiently definite structure for performing the recited function. None of the limitations of claims 1-10 recite the term “means” or a generic placeholder in combination with functional language. Rather, each of the “heat conduction path,” “first heat conduction member,” “second heat conduction member,” “stage extension component,” “heat conduction plate,” and “thermal resistance element” limitations recites a specific physical structure (a path, a member, a component, a plate, an element) that one of ordinary skill in the art would understand as connoting definite structure, and each such term is further described in the specification in purely structural terms (e.g., ¶¶ 0049-0059). Accordingly, no claim limitation of claims 1-10 has been construed under 35 U.S.C. 112(f), and no corresponding structure has been identified for any limitation on this basis.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 2 and 8 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 2 depends from claim 1, wherein claim 1 recites a pre-cooling cryocooler comprising only “a pre-cooling stage,” undifferentiated as to whether the pre-cooling cryocooler has one, two, or more pre-cooling stages. Claim 2 recites that “the heat conduction path comprises: a first heat conduction member thermally coupled to the pre-cooling stage and extending from the pre-cooling stage to a side opposite to the cylinder, and a second heat conduction member that thermally couples the first heat conduction member to the heat exchanger.” The specification's only disclosed embodiment of a first/second heat conduction member of this kind — the stage extension component 50 and heat conduction plate 52 shown in Figs. 2 and 3 - is described exclusively in the context of the second pre-cooling stage 27 of a pre-cooling cryocooler having both a first pre-cooling stage 25 and a second pre-cooling stage 27, i.e., the two-pre-cooling-stage embodiment first introduced in claim 3 (¶¶ 0041-0052; Figs. 1-3). The specification does not describe, and a skilled artisan reading the specification would not understand the inventor to have had possession of, a first heat conduction member and second heat conduction member of the recited kind used with a pre-cooling cryocooler having only a single, undifferentiated pre-cooling stage, as broadly claimed in claim 1 and claim 2. Claim 2 is therefore broader than, and not commensurate in scope with, the written description of the invention.
Claim 8 depends from claim 2 and recites that “the heat conduction path comprises a thermal resistance element between the heat exchanger and the second heat conduction member, and a thermal conductivity of the thermal resistance element is smaller than a thermal conductivity of the second heat conduction member.” The specification discloses a thermal resistance element 60 having a thermal conductivity lower than that of a heat conduction member only in the specific context of the second heat conduction path 48b, connecting the second pre-cooling stage 27 to the third heat exchanger 42c via the heat conduction plate 52 (¶¶ 0058-0059). While ¶ 0064 states that the thermal resistance element 60 “may be provided in the first heat conduction path 48a” connecting the second pre-cooling stage 27 to the second heat exchanger 42b “if necessary,” the specification does not describe the comparative thermal-conductivity relationship recited in claim 8 in that context, nor in the context of claim 2's broader, undifferentiated single-pre-cooling-stage embodiment discussed in part (A) above. Claim 8 is therefore broader than, and not commensurate in scope with, the written description of the invention.
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 3, 4, 5, 6, 9, and 10 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.
Claim 3 depends from claim 1. Claim 1 recites “a pre-cooling stage,” “a heat exchanger,” and “a refrigerant pipe extending from the heat exchanger and cooled by the pre-cooling stage.” Claim 3 then recites that “the pre-cooling cryocooler comprises a first pre-cooling stage and a second pre-cooling stage,” that “the refrigerant circuit comprises a first heat exchanger, a second heat exchanger …, and a third heat exchanger,” and that “the refrigerant pipe extends from the second heat exchanger via the second pre-cooling stage to the third heat exchanger.” Claim 3 does not state whether its “first pre-cooling stage” and “second pre-cooling stage” particularize, and are the same element as, “the pre-cooling stage” of claim 1, or whether they are additional elements; nor does it state whether its “first heat exchanger,” “second heat exchanger,” and “third heat exchanger” particularize, and are the same element as, “the heat exchanger” of claim 1, or whether they are additional elements. As filed, it cannot be determined which, if any, of the “first pre-cooling stage” and “second pre-cooling stage” of claim 3 corresponds to “the pre-cooling stage” of claim 1, and which, if any, of the “first heat exchanger,” “second heat exchanger,” and “third heat exchanger” of claim 3 corresponds to “the heat exchanger” of claim 1. This lack of clear antecedent basis renders the metes and bounds of claim 3 indefinite.
Claims 4, 5, 6, 9 and 10 are also rejected under 35 U.S.C. 112(b) for being dependent upon a rejected claim.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
Claims 1, 2, 3, 4, 5, 6, 7, and 9 are rejected under 35 U.S.C. 103 as being unpatentable over Zhu (US 7,207,191 B2) in view of Amthor (US 2018/0347866 A1).
In regard to claim 1, Zhu teaches a Joule-Thomson cryocooler (a cryogenic refrigerator including a main refrigeration circuit 1 formed as a Joule-Thomson circuit having a Joule-Thomson valve 24) comprising:
a pre-cooling cryocooler (pulse tube refrigerator 3) that comprises a pre-cooling stage (first cold head 31 and/or second cold head 32) (col. 7, ll. 60-67; col. 9, ll. 5-20; Fig. 1);
a refrigerant circuit (main refrigeration circuit 1) that comprises a heat exchanger (heat exchanger 22) and a refrigerant pipe (high pressure passage 1a) extending from the heat exchanger and cooled by the pre-cooling stage, the high pressure passage 1a including a second pre-cooling portion 1f that is thermally coupled to, and cooled by, the second cold head 32 (col. 7, ll. 12-30; col. 9, ll. 8-35; Fig. 1); and
Zhu does not explicitly teach a heat conduction path that is provided separately from the refrigerant pipe and connects the pre-cooling stage to the heat exchanger to enable conductive cooling of the heat exchanger through the pre-cooling stage.
However, Amthor teaches a cryogenic cooling system comprising a two-stage cryogenic cold head (24) having a first stage member (26) and a second stage member (30), and at least one thermal connection member (136/236/336/436) configured to provide at least a portion of a heat transfer path (138/238/338/438) from the second stage member to the first stage member, wherein the heat transfer path is arranged outside the cold head, i.e., separately from the cold head's internal working-fluid circuit, and wherein a thermal resistance of the heat transfer path at the (colder) second cryogenic temperature is larger than a thermal resistance of the heat transfer path at the (warmer) first cryogenic temperature, so that the heat transfer path provides an effective, low-resistance conductive-cooling path between the stage members during an initial, warmer cool-down period (Abstract; ¶¶ 0010-0011, 0019; Fig. 3).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the cryogenic refrigerator of Zhu to include a heat conduction path, provided separately from the high pressure passage 1a, connecting a pre-cooling stage (e.g., second cold head 32) to a heat exchanger (e.g., heat exchanger 22) of the main refrigeration circuit 1 to enable conductive cooling of the heat exchanger through the pre-cooling stage, as taught by Amthor, in order to shorten the cool-down time of the refrigerant at the heat exchanger by supplementing the cooling already provided through the refrigerant pipe with a direct, external conductive heat-transfer path to the pre-cooling stage (Amthor, Abstract; ¶ 0019).
In regard to claim 2, the modified Zhu as discussed above teaches the Joule-Thomson cryocooler of claim 1, wherein the pre-cooling cryocooler comprises a cylinder (first pulse tube 34 and/or first thermal accumulator 33, each embodied as a cylindrical tube) extending from the pre-cooling stage (first cold head 31) (Zhu, col. 9, ll. 1-8; Fig. 1), and the heat conduction path comprises:
Zhu does not explicitly teach that the heat conduction path comprises a first heat conduction member thermally coupled to the pre-cooling stage and extending from the pre-cooling stage to a side opposite to the cylinder, and a second heat conduction member that thermally couples the first heat conduction member to the heat exchanger.
However, Amthor teaches a thermal connection member (236) comprising a bimetal member (252) having a first end (254) fixedly attached and thermally connected, via a connecting copper flange (32), to a stage member (30), a first heat conduction member thermally coupled to a stage and extending away from that stage, outside the cold head's internal components, and a heat conductive member (46), formed as a copper metal plate, fixedly attached and thermally connected to the other stage member (26) and protruding toward the second end (256) of the bimetal member so as to thermally couple the bimetal member to that other stage member - a second heat conduction member that thermally couples the first heat conduction member to the component being cooled (¶¶ 0068-0069; Fig. 4).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have configured the heat conduction path of the modified Zhu with a first heat conduction member thermally coupled to the pre-cooling stage and extending from the pre-cooling stage to a side opposite to the cylinder, and a second heat conduction member thermally coupling the first heat conduction member to the heat exchanger, as taught by Amthor, in order to route the supplemental conductive-cooling path from the pre-cooling stage to the heat exchanger along a path outside of, and without mechanically interfering with, the cylindrical components of the pre-cooling cryocooler, consistent with Amthor's teaching of arranging the heat transfer path outside the cold head (Amthor, Abstract; ¶ 0062). One of ordinary skill would have been motivated to make this modification because Zhu's cold heads are structurally arranged in line with their respective cylindrical pulse-tube and thermal-accumulator components (Zhu, col. 9, ll. 1-8), so that an artisan adding a supplemental conduction path as suggested by Amthor would naturally route the added heat conduction members clear of those cylindrical components. See KSR, 550 U.S. 398; MPEP § 2143(I)(x).
In regard to claim 3, the modified Zhu teaches the Joule-Thomson cryocooler of claim 1, wherein the pre-cooling cryocooler comprises a first pre-cooling stage (first cold head 31, cooled to approximately 80K) and a second pre-cooling stage (second cold head 32, cooled to approximately 12K) that is cooled to a lower temperature than the first pre-cooling stage (col. 9, ll. 5-8; Fig. 1);
the refrigerant circuit comprises a first heat exchanger (heat exchanger 21), a second heat exchanger (heat exchanger 22) that further cools a refrigerant cooled by the first heat exchanger, and a third heat exchanger (heat exchanger 23) that further cools the refrigerant cooled by the second heat exchanger (col. 7, ll. 24-30; col. 9, ll. 21-40), and the refrigerant pipe extends from the second heat exchanger via the second pre-cooling stage to the third heat exchanger, the high pressure passage 1a extending from heat exchanger 22 through the second pre-cooling portion 1f, thermally coupled to the second cold head 32, to heat exchanger 23 (col. 9, ll. 26-35; Fig. 1); and
Zhu does not explicitly teach that the heat conduction path connects the second pre-cooling stage to at least one of the second heat exchanger and the third heat exchanger to enable conductive cooling of the at least one of the second heat exchanger and the third heat exchanger through the second pre-cooling stage.
However, as discussed above in the rejection of claim 1, Amthor teaches a heat transfer path connecting a colder stage member to a component that is otherwise thermally coupled only through the working-fluid circuit to a warmer, higher-capacity stage of a two-stage cryogenic cooling system, so as to conductively cool that component through the stage (¶¶ 0010-0011, 0019).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the modified Joule-Thomson cryocooler of Zhu so that the heat conduction path connects the second pre-cooling stage (second cold head 32) to at least one of the second heat exchanger (22) and the third heat exchanger (23), to enable conductive cooling of that heat exchanger through the second pre-cooling stage, as taught by Amthor, in order to accelerate the cool-down of the heat exchanger or heat exchangers positioned closest to the coldest pre-cooling stage, which take the longest to cool through the refrigerant flow alone.
In regard to claim 4, the modified Zhu teaches the Joule-Thomson cryocooler of claim 3, but does not explicitly teach that the heat conduction path connects the second pre-cooling stage to the second heat exchanger, specifically, to enable conductive cooling of the second heat exchanger through the second pre-cooling stage.
However, as discussed above in the rejection of claim 3, Amthor teaches a heat transfer path connecting a colder stage member to a component to be conductively cooled through a warmer, higher-capacity stage member of a two-stage cryogenic cooling system (¶¶ 0010-0011, 0019).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have connected the heat conduction path of the modified Joule-Thomson cryocooler of Zhu to the second heat exchanger (22), specifically, to enable conductive cooling of the second heat exchanger through the second pre-cooling stage (32), as taught by Amthor, in order to accelerate the cool-down of the second heat exchanger (22), which receives refrigerant immediately upstream of the coldest pre-cooling stage and heat exchanger of the main refrigeration circuit and therefore contributes materially to the overall cool-down time of the Joule-Thomson circuit (Zhu, col. 9, ll. 21-35).
In regard to claim 5, the modified Zhu teaches the Joule-Thomson cryocooler of claim 3, wherein Zhu teaches the pre-cooling cryocooler comprises a cylinder (second thermal accumulator 35 and/or second pulse tube 36, each embodied as a cylindrical tube) that connects the second pre-cooling stage (second cold head 32) to the first pre-cooling stage (first cold head 31) (col. 9, ll. 1-8; Fig. 1).
Zhu does not explicitly teach that the heat conduction path comprises a stage extension component thermally coupled to the pre-cooling stage and extending from the pre-cooling stage to a side opposite to the cylinder, and a heat conduction plate that thermally couples the stage extension component to the at least one of the second heat exchanger and the third heat exchanger.
However, Amthor teaches a thermal connection member (236) comprising a bimetal member (252) having a first end (254) fixedly attached and thermally connected, via a connecting copper flange (32), to a stage member (30), a stage extension component thermally coupled to a stage and extending away from that stage, and a heat conductive member (46), formed as a copper metal plate, fixedly attached and thermally connected to the other stage member (26) and protruding toward the second end (256) of the bimetal member so as to thermally couple the bimetal member to that other stage member - a heat conduction plate that thermally couples the stage extension component to the component being cooled (¶¶ 0068-0069; Fig. 4).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have configured the heat conduction path of the modified Joule-Thomson cryocooler of Zhu with a stage extension component thermally coupled to the second pre-cooling stage and extending from the second pre-cooling stage to a side opposite to the cylinder connecting the second pre-cooling stage to the first pre-cooling stage, and a heat conduction plate that thermally couples the stage extension component to the at least one of the second heat exchanger and the third heat exchanger, as taught by Amthor, in order to route the supplemental conductive-cooling path clear of the cylindrical thermal-accumulator and pulse-tube components connecting the two pre-cooling stages, consistent with Amthor's teaching of arranging the heat transfer path outside the cold head (Amthor, Abstract; ¶ 0062).
In regard to claim 6, the modified Zhu teaches the Joule-Thomson cryocooler of claim 5, wherein Neither Zhu nor Amthor explicitly states that the at least one of the second heat exchanger and the third heat exchanger and the stage extension component are disposed on the same side of the heat conduction plate.
However, mounting the stage extension component and the heat exchanger to be cooled on a common side of the heat conduction plate is a mere rearrangement of the parts of the heat conduction path already taught, in combination, by Zhu and Amthor, and would yield no more than the predictable result of a compact, single-sided mounting arrangement.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have disposed the at least one of the second heat exchanger and the third heat exchanger and the stage extension component of the modified Joule-Thomson cryocooler of Zhu on the same side of the heat conduction plate, in order to simplify assembly of the heat conduction path and minimize the number of thermal interfaces required to route heat from the pre-cooling stage to the heat exchanger. One of ordinary skill would have been motivated to make this modification because arranging cooperating, thermally coupled components on a common side of a mounting plate is a matter of routine engineering choice yielding predictable results. See In re Japikse, 181 F.2d 1019 (CCPA 1950); KSR, 550 U.S. 398; MPEP § 2143(I)(x).
In regard to claim 7, the modified Zhu teaches the Joule-Thomson cryocooler of claim 1, but Zhu does not explicitly teach that the heat conduction path comprises a thermal resistance element.
However, Amthor teaches that the heat transfer path (138/238/338/438) exhibits a thermal resistance that is deliberately made larger at the second (colder) cryogenic temperature than at the first (warmer) cryogenic temperature, i.e., the heat transfer path comprises a thermal-resistance-bearing element or region positioned along the path between the stage members (Abstract; ¶¶ 0011, 0014-0015, 0019, 0027, 0033).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have incorporated a thermal resistance element into the heat conduction path of the modified Joule-Thomson cryocooler of Zhu, as taught by Amthor, in order to limit the parasitic heat load conducted into the pre-cooling stage through the heat conduction path once the heat exchanger has reached its normal, steady-state operating temperature (Amthor, Abstract; ¶ 0019). One of ordinary skill would have been motivated to make this modification because, absent such a thermal resistance element, the supplemental conduction path added to Zhu's cryogenic refrigerator to accelerate cool-down would otherwise continue to conduct heat into the pre-cooling stage during normal operation, degrading the very refrigeration performance that Zhu's own disclosure seeks to improve (Zhu, col. 2, ll. 40-48).
In regard to claim 9, the modified Zhu teaches the Joule-Thomson cryocooler of claim 3, but Zhu does not explicitly teach that the heat conduction path connects the second pre-cooling stage to the third heat exchanger via a thermal resistance element.
However, as discussed above in the rejection of claim 7, Amthor teaches incorporating a thermal-resistance-bearing element along a conduction path connecting a cryogenic cooling stage to a component to be conductively cooled (Amthor, Abstract; ¶¶ 0011, 0019).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have connected the second pre-cooling stage (32) to the third heat exchanger (23) of the modified Joule-Thomson cryocooler of Zhu via a thermal resistance element, as taught by Amthor, in order to limit the parasitic heat load conducted into the second pre-cooling stage from the third heat exchanger during normal, steady-state operation, while still permitting accelerated conductive cool-down of the third heat exchanger, which receives refrigerant immediately upstream of the Joule-Thomson valve and refrigeration means and is therefore most in need of a fast, low-temperature cool-down path (Zhu, col. 8, ll. 1-14; col. 9, ll. 33-40).
Claims 8 and 10 are rejected under 35 U.S.C. 103 as being unpatentable over Zhu (US 7,207,191 B2) in view of Amthor (US 11,274,857 B2), and further in view of Dhuley (US 2021/0356193 A1).
In regard to claim 8, the modified Zhu teaches the Joule-Thomson cryocooler of claim 2, but Zhu does not explicitly teach that the heat conduction path comprises a thermal resistance element between the heat exchanger and the second heat conduction member, and that a thermal conductivity of the thermal resistance element is smaller than a thermal conductivity of the second heat conduction member.
However, Amthor teaches a heat conductive member (46), formed as a copper metal plate (the second heat conduction member) (¶ 0069), against which the second end (256) of the bimetal member bears with a mechanical surface pressure that varies with temperature, the resulting mechanical contact interface presenting a thermal resistance to conduction between the bimetal member and the heat conductive member that is deliberately made larger, i.e., a lower effective thermal conductivity - than the bulk thermal conductivity of the copper heat conductive member itself, so as to establish a temperature-dependent thermal resistance along the heat transfer path (claim 6 of Amthor; ¶¶ 0069-0070). Dhuley further teaches, as an alternative and explicitly material-based implementation of the same principle, a thermal switch positioned in a copper conduction path (claim 17 of Dhuley) whose switch body is formed of steel or another material having a low thermal conductivity relative to the copper conduction path (¶ 0086; Fig. 10A), i.e., a discrete element whose thermal conductivity is smaller than that of the surrounding copper heat conduction path.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have positioned a thermal resistance element, having a thermal conductivity smaller than that of the second heat conduction member, between the heat exchanger and the second heat conduction member of the modified Joule-Thomson cryocooler of Zhu, as taught by Amthor and Dhuley, in order to limit the parasitic heat load conducted from the heat exchanger into the pre-cooling stage once the heat exchanger has reached its normal, steady-state operating temperature (Amthor, Abstract; ¶ 0019; Dhuley, ¶¶ 0083-0084, 0086). One of ordinary skill would have been motivated to make this modification for the same reasons discussed above in the rejection of claim 7, and would have had a reasonable expectation of success in selecting a discrete, lower-conductivity material for the thermal resistance element given Dhuley's express teaching that a switch body of steel, having a low thermal conductivity relative to the copper conduction path, achieves this same function.
In regard to claim 10, the modified Zhu teaches the Joule-Thomson cryocooler of claim 5, but Zhu does not explicitly teach that the heat conduction path comprises a thermal resistance element between the third heat exchanger and the heat conduction plate, and that a thermal conductivity of the thermal resistance element is smaller than a thermal conductivity of the heat conduction plate.
However, Amthor teaches a heat conductive member (46), formed as a copper metal plate (the heat conduction plate) (¶ 0069), against which the second end (256) of the bimetal member (the stage extension component) bears with a mechanical surface pressure that varies with temperature, the resulting mechanical contact interface presenting a thermal resistance to conduction that is deliberately made larger, i.e., a lower effective thermal conductivity, than the bulk thermal conductivity of the copper heat conductive member itself (claim 6 of Amthor; ¶¶ 0069-0070). Dhuley further teaches, as an alternative and explicitly material-based implementation of the same principle, a thermal switch positioned in a copper conduction path (claim 17 of Dhuley) whose switch body is formed of steel or another material having a low thermal conductivity relative to the copper conduction path (¶ 0086; Fig. 10A).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have positioned a thermal resistance element, having a thermal conductivity smaller than that of the heat conduction plate, between the third heat exchanger and the heat conduction plate of the modified Joule-Thomson cryocooler of Zhu, as taught by Amthor and Dhuley, in order to limit the parasitic heat load conducted from the third heat exchanger into the second pre-cooling stage once the third heat exchanger has reached its normal, steady-state operating temperature (Amthor, Abstract; ¶ 0019; Dhuley, ¶¶ 0083-0084, 0086).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to WEBESHET MENGESHA whose telephone number is (571)270-1793. The examiner can normally be reached Mon-Thurs 7-4, alternate Fridays, EST. 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, Frantz Jules can be reached at 571-272-6681. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/W.M/Examiner, Art Unit 3763
/FRANTZ F JULES/Supervisory Patent Examiner, Art Unit 3763
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