HAYS, Circuit Judge.
This is an appeal from a judgment of the District Court, holding invalid for lack of invention Patent No. 2,880,785, issued on April 7, 1959 to Fridtjof F. Schliephacke, plaintiff’s assignor. We affirm the judgment.
The patent involves a mechanism for the operation of a reclining chair with a movable leg-rest. Chairs with leg-rests that rise to a horizontal position when the back is reclined were widely used prior to this patent. The patent in suit was intended to cover only a new design of the hardware that is.used to accomplish that result and not the chair itself.
In a chair equipped with the Sehliephacke device, the leg-rest is elevated from a vertical to a horizontal position by the interaction of a lazy-tong linkage and a single actuating link. The lazy-tong linkage, consisting of two sets of links, pivotally connected at a point on the forward link of the rear set and the rear link of the forward set, is pivoted to the leg-rest at one end of each set. The opposite end of each linkage is pivot-ally connected to the side of the seat toward the front. The rear link of the rear linkage has a short angular extension pointing downward. The actuating link is pivotally connected to the end of this extension and to the base of the chair.
A lazy-tong linkage will raise a leg-rest to which it is pivotally attached when a forward force is applied to the rear link. In the Schliephacke device, that force is provided by the direct actuating link which remains fixed when the seat, to which the lazy-tongs are attached, moves upward and back. The seat is linked to the base and the back of the chair in such a way that it moves upward and back when the back of the chair is reclined.
That the Schliephacke patent is “new and useful” (35 U.S.C. § 101 (1958)) is attested to by its widespread acceptance by the trade. The record shows that in 1959 and 1960, manufactured by both licensees and non-licensees, the device completely dominated the trade.
The question on which this appeal turns therefore is whether the patent in suit satisfies the requirements of 35 U. S.C. § 103 (1958):
“Conditions for patentability; non-obvious subject matter. A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains. * * * ”
We agree with Judge Dawson, who, in the court below, reviewed the prior art and held the patent invalid for failure to meet this statutory test.
Both the lazy-tong linkage and the direct actuating link were known in the prior art. Lazy-tong linkages, substantially the same as those employed in the Schliephacke device, appear in Lorenz, Patent No. 2,781,824, issued February 19, 1957; Lorenz, Patent No. 2,843,184, issued July 15, 1958; Luckhardt, Patent No. 2,870,822, issued January 27, 1959, and Bank et al., Patent No. 2,838,093, issued June 10, 1958. In the first three the lazy-tongs are actuated by a link connecting a lower extension of the chair backs to a point on the lazy-tongs. The reclining of the back in relation to the lesser movement of the seat sends the extension forward and provides the force for raising the leg-rest. In the Bank device a similar connecting link is employed but it connects the lazy-tongs with a lower extension from the seat of the chair rather than with the back. It is the incline of the seat, rather than the back, that provides the force and the device can thus be used regardless of whether the back moves in relation to the seat.
Luckhardt et al., Patent No. 2,276,053, issued March 10, 1942, shows a single linkage pivotally attached at one end to the leg-rest and at the other to a lower extension from the seat. Near the end of this latter link on the front side a single direct actuating link is pivotally attached. The other end of the actuating link is pivotally attached to the lower frame of the chair. Exactly as in the Schliephacke device, the fixed position of the actuating link prevents the linkage from moving back with the seat and thus actuates it, causing the leg-rest to rise. Compare Greaves & Thomas, Ltd., British Patent No. 737,396, issued September 28, 1955.
Thus, the Schliephacke device combines the direct actuating link so clearly demonstrated in the Luckhardt patent with the lazy-tong linkage repeatedly shown in other patents. It would be difficult indeed to conclude that this combination of proven ingredients each performing the identical function performed in the earlier separate applications is something that would not have been “obvious to a person having ordinary skill in the art.” Great Atl. and Pac. Tea Co. v. Supermarket Equipment Corp., 340 U.S. 147, 151-153, 71 S.Ct. 127, 129, 130, 95 L.Ed. 162 (1950); Lincoln Engineering Co. v. Stewart-Warner Corp., 303 U.S. 545, 549, 58 S.Ct. 662, 664, 82 L.Ed. 1008 (1938).
Appellant points to the commercial success of the Schliephacke device and argues that if the combination was in fact obvious to a worker skilled in the art, some such worker would have combined the lazy-tong linkage and the direct actuating link before Schliephacke. Commercial success by itself does not establish the validity of a patent. However, in a proper case it is relevant on the issue of obviousness that the patent under attack served to satisfy a “long felt want.” Reiner v. I. Leon Co., 285 F.2d 501, 504 (2d Cir. 1960), cert. denied, 366 U.S. 929, 81 S.Ct. 1649, 6 L.Ed.2d 388 (1961). Here, the only evidence of “long felt want” is the relatively large number of patents issued on reclining chair hardware in recent years, an indication of considerable interest in the improvement of these devices, together with the immediate adoption of the Sehliephacke device by the trade. Appellant cannot point to a specific problem to which workers in the field were directing their attention and which was solved by the Sehliephacke device. As we said in E. J. Brooks Co. v. Stoffel Seals Corp., 266 F.2d 841, 842 (2d Cir.), cert. denied, 361 U.S. 883, 80 S.Ct. 154, 4 L.Ed.2d 119 (1959):
“But apart from the usual and common desire of manufacturers constantly to improve their product —the stimulus of nearly all routine engineering improvements — there is no evidence of any specific and recognized problems which the claimed invention solved.”
Appellant places great weight on the presumption of validity attached by statute to a duly issued patent (35 U.S.C. § 282 (1958)). The presumption of validity relieves the patent holder of the .burden of establishing that validity as a requisite for the successful maintenance of an infringement action, and places the burden of establishing invalidity on the alleged infringer who asserts it. International Carrier-Call & Television Corp. v. Radio Corp. of America, 142 F.2d 493, 495 (2d Cir. 1944) ; Western States Mach. Co. v. S. S. Hepworth Co., 147 F.2d 345, 348 (2d Cir.), cert. denied, 325 U.S. 873, 65 S.Ct. 1414, 89 L.Ed. 1991 (1945). More than that, the most that can be said of the presumption is that it requires that reasonable doubt on the question of validity be resolved in favor of the patent holder. See Mumm v. Decker & Sons, 301 U.S. 168, 171, 57 S.Ct. 675, 81 L.Ed. 983 (1937). The statute does not require that the presumption be accorded the weight of actual evidence or that the use of the presumption should affect a decision of invalidity that would otherwise be reached with confidence. This court has recognized the unavoidable obstacles to an accurate and impartial decision that are inherent in ex parte proceedings in the patent office, Guide v. Desperak, 249 F.2d 145, 148 (2d Cir. 1957). We cannot properly allow decisions of that office to alter the preponderance of the evidence on the question of validity. See Great Atlantic & Pacific Tea Co. v. Supermarket Equipment Corp., 340 U.S. 147, 156, 71 S.Ct. 127, 95 L.Ed. 162 (1950); In re Thomson, 26 App.D.C. 419, 425 (1906); cf. Lyon v. Bob, 1 F.2d 48 (S.D.N.Y.1924) (L. Hand, J.), rev’d, 10 F.2d 30 (2d Cir. 1926). In the present case, defendant satisfied his burden of coming forward with evidence of invalidity and we have no such doubts on the question as would bring the presumption further into play.
. The improvements concern “balance” of the chair and economy of production.
. “The conjunction or concert of known elements must contribute something; only when the whole in some way exceeds the sum of its parts is the accumulation of old devices patentable. * * *
“Courts should scrutinize combination patent claims with a care proportioned to the difficulty and improbability of finding invention in an assembly of old elements. The function of a patent is to add to the sum of useful knowledge. Patents cannot be sustained when, on the contrary, their effect is to subtract from former resources freely available to skilled artisans. A patent for a combination which only unites old elements with no change in their respective functions, such as is presented here, obviously withdraws what already is known into the field of its monopoly and diminishes the resources available to skillful men. * * * ” 340 U.S. at 152-153, 71 S.Ct. at 130.
. “The mere aggregation of a number of old parts or elements which, in the aggregation, perform or produce no new or different function or operation than that theretofore performed or produced by them, is not patentable invention.” 303 U.S. at 549, 58 S.Ct. at 664 (1938).
. “The fact that this process has enjoyed considerable commercial success, however, does not render the patent valid. It is true that in cases where the question of patentable invention is a close one, such success has weight in tipping the scales of judgment toward patentability. [Citation.] Where, as here, however, invention is plainly lacking, commercial success cannot fill the void. [Citations.]” Jungersen v. Ostby & Barton Co., 335 U.S. 560, 567, 69 S.Ct. 269, 272, 93 L.Ed. 235 (1949). See Magnus Harmonica Corp. v. Lapin Products, 236 F.2d 285 (2d Cir. 1956); Vermont Structural Slate Co. v. Tatko Bros. Slate Co., 233 F.2d 9, 11 (2d Cir.), cert. denied, 352 U.S. 917, 77 S.Ct. 216, 1 L.Ed.2d 123 (1956).
It should be added that in cases of patents on devices improving an existing product, there is every reason to severely limit the weight attributed to commercial success. The distinction between a mere improvement and an invention is well known in the law of patents, and incorporation of a device by manufacturers can be explained solely by the former. See Minnesota Mining & Mfg. Co. v. Industrial Tape Corp., 168 F.2d 7, 11 (7th Cir.), cert. denied, 335 U.S. 829, 69 S.Ct. 56, 93 L.Ed. 382 (1948). Moreover the volume of sales of chairs utilizing the Schliephacke device is irrelevant, when there is nothing in the record to show that sales were attributable to the improvement, or that sales of reclining chairs increased when the Schliephacke mechanism was adopted. See Welsh Manufacturing Co. v. Sunware Products Co., 236 F.2d 225, 227 (2d Cir.1956).
. See note 6, infra.
. Since 1950, eighteen patents on different variations of hardware for use in reclining chairs with movable leg-rests have been issued. Obviously there have not been eighteen “inventions” in this narrow area in the last twelve years. When inconsistent monopoly grants thus seemingly flow from the Patent Office, it is clear that the weight to be attached to the determination of patent examiners must be very limited, and is totally unlike the weight accorded the determination of an administrative agency made after an adversary proceeding.
. In addition, it should be pointed out that none of the particular patents evidencing prior art which were relied on by the court below or by this court were called to the attention of the patent examiner and there was no intervention in opposition to the issuance of the Sehliephacke patent. Both of these factors tend to weaken or negate the presumption. Cutler Mail Chute Co. v. Capitol Mail Chute Corp., 118 F.2d 63, 64 (2d Cir.), cert. denied, 313 U.S. 580, 61 S.Ct. 1096, 85 L.Ed. 1537 (1941); Celanese Corp. v. Essley, 98 F.2d 895 (2d Cir.1938) petition for cert. dismissed, 307 U.S. 649, 59 S.Ct. 836, 83 L.Ed. 1528 (1939); R. Hoe & Co. v. Goss Printing Press Co., 30 F.2d 271, 274 (2d Cir.1929); see Alco Kar Kurb Inc. v. Ager, 286 F.2d 931 (3d Cir.1961). However, although it is not clear whether he is correct, appellant argues that other patents that were considered by the patent examiner reveal the same elements of the prior art.