Opinion
This case having been heard by the Court of Claims, the court, upon the evidence and report of a commissioner, makes the following special findings of Fact:
1. On August 27, 1929, United States letters patent, No. 1,726,500, were issued on an application filed in the patent office by Ralph Forbush Norris on February 25, 1929. This application was a continuation of a prior application filed by Norris on August 11, 1927. It covered sound-deadening construction.
2. The Norris patent 1,726,500 when granted was issued to C.F. Burgess Laboratories, Inc., of Madison, Wisconsin, as assignee of Ralph Forbush Norris prior to issue.
On August 31, 1938, C.F. Burgess Laboratories, Inc., executed an instrument assigning the patent in suit to Burgess Battery Company, a Wisconsin corporation, together with the right to recover for past infringement.
The Burgess Battery Company, of Delaware, is a corporation resulting from a reorganization of the Burgess Battery Company, a Wisconsin corporation. As a part of the plan of reorganization, the patent issued to C.F. Burgess Laboratories, Inc., was assigned to the plaintiff by the Wisconsin corporation, together with the right to recover for past infringement.
3. Sound-deadening devices constructed in accordance with the patent in suit were placed on sale by plaintiff's predecessor in 1927. In 1929 plaintiff's predecessor, C.F. Burgess Laboratories, Inc., discontinued the manufacture of the product covered by the patent and granted a license to the Johns-Manville Corporation under certain inventions which included the sound-deadening construction covered by the Norris patent.
Subsequent to the above-mentioned license a number of other licenses were granted to the beginning of the present suit, all of these licenses including rights to manufacture and use the Norris invention upon which the patent in suit is based. The licensees manufactured and sold devices made in accordance with the patent in suit and substantial royalties were collected under these licenses.
4. Notice of infringement of the Norris patent was given to the Navy Department on behalf of the C.F. Burgess Laboratories, Inc., by a letter dated July 22, 1938, and on behalf of the Burgess Battery Company, a Wisconsin corporation, by a letter dated May 19, 1939.
5. The patent in suit has been involved in previous litigation in the case of C.F. Burgess Laboratories, Inc., v. Coast Insulating Corp., United States District Court for the Southern District of California. The District Court's opinion in this case is published at 27 F.Supp. 956. Appeal was taken from this decision to the Ninth Circuit Court of Appeals, whose opinion is published at Burgess Battery Co. v. Coast Insulating Corporation, 114 F.2d 779. Claims 1, 3, 4, 5, 6, 8, 10, 11, 14, 16, 17, and 23 were in issue in the District Court. Claim 4 was held valid and infringed; claims 16, 17, and 23 held not infringed, and the remaining claims at issue were held invalid for indefiniteness and as being too broad and general in view of the prior art. The appeal was prosecuted only on the claims which were held invalid and not infringed. The Court of Appeals held claims 1, 3, 5, 6, 8, 10, 11, and 14 invalid, and claims 16, 17, and 23 not infringed.
Sound, Transmission, and Absorption
6. Sound in the ordinary accepted sense of the term is a wave motion of the air which originates when a body is set into vibration. The vibrations of the generating body are transmitted to the surrounding air and result in waves of alternating condensation and rarefaction of the atmosphere. These waves are propagated in all directions from the source of the sound with a velocity of 1,120 feet per second at ordinary temperatures.
The vibrations which the human ear can perceive range from a frequency of 20 per second to approximately20,000 per second. Acoustical engineers in dealing with sound equipment usually consider the range of from 60 to 10,000 vibrations per second. Sounds of different frequencies possess different wavelengths. For example, sound at 128 vibrations per second has a wavelength of 9 feet, and sound at 4,000 vibrations per second has a wavelength of something like 3 1/2 inches.
The sound waves from a source of sound may vary in character. Middle C on the piano gives a musical tone of 256 vibrations per second, and the waves emanating therefrom are made up of a definite fundamental pitch or tone, together with certain harmonics. This is a relatively simple wave structure as compared to the clicking of a typewriter, which is an unpitched sound and possesses various frequencies which lie in the range from 1,000 to 4,000 vibrations.
7. When a sound is generated in an enclosed space, such as a room, the sound waves strike the interior surfaces of the room, and if these are of ordinary building material such as concrete or hard plaster, which are good sound reflectors, the waves continue to be reflected back and forth and around the room and in all directions until the sound is absorbed to a degree so that it is no longer audible. This continued reflection, which is termed "reverberation," may be present to such an extent that syllables of speech often apparently run together and are indistinct and difficult to understand. Reverberation, which in popular parlance may be said to make a room "noisy," is the cause of the majority of acoustical difficulties, and the principles involved in the present issue deal with the treatment of surfaces of enclosures so that the sound waves will be absorbed instead of reflected.
8. The action of various surfaces on sound waves is similar to that taking place with light waves in that no surface can be considered as 100 percent reflecting or 100 percent absorbing, and the majority of surfaces and materials both reflect and absorb sound to some extent.
Absorption of sound waves implies the dissipation of the vibrational energy. As an example, sound may be absorbed by the compressional motion of the individual fibers of an inelastic flexible and compressible material such as felt. A thick layer of felt or similar material will yield to the alternating pressure of sound waves and in so yielding will absorb a part of the sound energy which strikes it.
Sound may also be absorbed due to the porosity of certain materials. The alternating pressure of a sound wave actuates the air particles in the numerous channels in the interior of the material, and the resulting friction in the pores of the material acts to dissipate the energy of the sound wave.
Viewed from the standpoint of physics, the energy itself does not dissipate, but is changed through friction from the vibrational energy known as sound into molecular motion of the particles of the material known as heat.
Sound-absorption material such as felt and rock wool owe their acoustical absorption both to their inelastic flexibility and compressibility, and also to their porosity.
9. Sound-reflecting and non-sound-absorbing materials in general may be exemplified by hard and unyielding surfaces such as steel or other metallic surfaces, concrete floors, plate glass, and ordinary plaster walls. Such surfaces reflect a large percentage of the sound waves striking them.
A sheet of material possessing elastic properties, when sufficiently thin to permit it to vibrate when sound waves impinge upon one of the surfaces, will transmit more or less sound wave energy to its opposite side, and to that extent may be said to be sound transparent. This is also a relative term, as a substance may be sound reflecting, sound absorbing and sound transparent to some extent.
While there is no clear line of demarcation between sound-absorbing surfaces and non-sound-absorbing surfaces, a material having an average absorption of less than 20 percent in the frequency range of from 256 cycles to 2,000 cycles per second would not usually be considered as sound absorbent.
10. The problem of treating a room or similarly enclosed space so that sounds created therein will be absorbed is not difficult when viewed from the acoustical standpoint alone. It is only necessary to line the walls and ceiling of a room with a heavy layer of sound-absorbing material such as felt or rock wool. While such a surface might be satisfactory from the acoustical standpoint, it would be subject to disintegration, and could not be cleaned, painted or decorated.
The problem presented to those skilled in the art therefore becomes one of providing a sound-absorbing surface which will be practical from a constructional, maintenance and architectural viewpoint as well as acoustically, and it is to this problem that the patent in suit is addressed.
The Patent in Suit
11. The thought or discovery expressed in the patent in suit is that when a layer of sound-absorbing material is structurally supported by a thin, rigid, self-sustaining membrane, such as sheet steel or similar sound-reflecting and non-sound-absorbing material, and this supporting sheet is provided with small perforations so spaced as to bear a certain relationship to the wave-lengths of the sound it is desired to absorb, such a composite structure will be equally or more efficient in sound absorption than the bare or unsurfaced layer of sound-absorbing material.
12. The specification gives instructions as to the use of the Norris structure. The patentee indicates that his invention is not limited to sheet metal but may be practiced by the use of other rigid sheet membranes such as vulcanized fibre sheets, bakelized sheets and veneered wood sheets, but indicates that he prefers using sheet metal. The patentee states that
"I prefer using a thin sheet metal membrane which may be composed of galvanized iron, tin or terne plate, ordinary black iron or stiff steel sheets. Other metals such as aluminum or duralumin sheets may be used for special locations."
With reference to the individual size of the perforations the patentee indicates that this is not dependent upon sound-absorbing characteristics but is controlled by such factors as ability to paint the sheet metal without plugging the perforations and the tendency of the sound-absorbing material to project through the perforations and be visible to the eye.
The relative total perforated area may apparently be anything from the specification as quoted below. Claim 14 however appears to establish the lower limit of 0.4%, and claim 11 the upper limit of 49 percent.
With reference to size and area, the patentee states
"These sheets may be perforated in any suitable manner. The perforations may, for example, cover from 0.4% to 35% of the area of the metal or other rigid sheet although I do not limit myself to this range, and excellent results are obtained with a sheet in which about 16% of the surface is perforated. The perforating must be done with due regard to the size of the perforation and also to the spacing between perforations. "The lower limit of size of the perforation usually is determined not by sound absorption considerations but by the difficulties resulting from the bridging over and closing of the perforation when the surface is painted. A found perforation 0.073 inches in diameter or any other shaped perforation having that minimum dimension is about the smallest that may be readily painted or enameled without plugging. The maximum size of a perforation is dependent upon the appearance of the tile and the tendency of the sound absorbing material to project through it and be visible to the eye. I favor a hole less than 0.125 inches for its minimum dimension where elongated holes are employed. A round hole 0.125 inches in diameter has an area of 0.0123 square inches. Holes smaller or larger than the dimensions given may be used."
13. With reference to the spacing of the holes, the patentee states
"I have found that the spacing of the holes should be determined by the pitch of the sound which is absorbed. The lower the pitch of the sound, that is, the smaller the number of double vibrations per second and the longer the wave length, the greater may be the distance between the holes to secure the same absorption."
The specification suggests the use of both round and elongated holes and in the case of the latter refers only to the minimum dimension.
14. The specification then proceeds to set forth a detailed description of the sound-absorption characteristics of panels of perforated metal having a 1-inch balsam-wool backing, and makes reference to Fig. 14 of the drawings, which is a graph.
As explained in the specification, this graph instructs those skilled in the art that as the pitch of the sound increases (i.e., the wave-length becoming shorter) it is necessary to decrease the spaces between the holes.
In connection with this graph, which relates to holes of 0.073 inch in diameter, it is stated that the 1-inch balsam-wool backing alone has a sound-absorption of about 74 percent. With sound at a pitch of 512 double vibrations per second and the use of a metal diaphragm having a distribution of one 0.073 inch diameter hole per square inch in combination with the balsam-wool backing, the sound absorption increases to 78 percent.
When the pitch of the sound is increased to 1,024 double vibrations per second the maximum absorption of 78 percent is reached with about two holes per square inch. The holes are stated to be about 0.706 inch apart on centers with this spacing.
At 2,046 double vibrations, the maximum absorption is reached at about four holes per square inch, with a spacing of 1/2 inch on centers.
15. With reference to the higher pitched sounds which are not directly shown on the graph, the same indicates that the number of holes per square inch must be increased. In this connection, the specification states
"Noises from typewriters, adding machines, dishes, and the like are high pitched (about 4,000 double vibrations per second). The curve of Fig. 14 indicates that the number of holes per square inch must be increased beyond 4 per square inch if the high-pitched noises are to be absorbed. I have determined that a sound absorber backed perforated sheet metal with 16 holes per square inch, 1/4 inch apart on centers gives maximum results for that absorber for most conditions, absorbing both the low and most high-pitched sounds. This spacing is for holes 0.073 inch in diameter. With this diameter the holes are on an average of 0.177 inch apart, measuring between nearest edges of holes."
16. The claims in suit are as follows:
"1. In the combination of sound-absorbing material and a facing therefor, a thin sheet of perforated metal forming such facing, the ratio of the unperforated area of said sheet to the openings therein being such as to expose an apparently substantially continuous surface to the sound waves.
"2. In the combination of sound-absorbing material and a facing therefor, a thin sheet of perforated metal forming such facing, the perforations being substantially uniformly distributed over the area of said sheet and the average dimensions of the individual openings being less than the distance between the edges thereof.
"3. In the combination of sound-absorbing material of high efficiency and means for confining and concealing the same, a thin layer of self-sustaining, non-sound-absorbing perforated material constituting such means, the openings therein being widely distributed over the area exposed to the sound waves and small enough to substantially conceal the sound-absorbing material.
"4. In the combination of sound-absorbing material of high efficiency and means for confining and concealing the same, a thin layer of self-sustaining, non-sound-absorbing perforated material constituting such means, the openings therein being widely distributed over the area exposed to the sound waves and the aggregate area of said openings totaling not more than about 16% of said first area.
"5. Sound-absorbing means comprising, in combination, sound-absorbing material and a thin, stiff member contiguous thereto with a plurality of openings therein, the ratio of openings to the area of said member being such as to expose an apparently substantially continuous surface to the sound waves.
"6. A sound-absorbing structure comprising sound-absorbing material and a thin, self-sustaining material concealing the same with a multiplicity of small openings therethrough of average dimensions greater than the thickness of said self-sustaining material.
"7. A sound-absorbing structure comprising sound-absorbing material and a thin, self-sustaining material concealing the same with a multiplicity of small openings therethrough of average dimensions greater than the thickness of said self-sustaining material and spaced from each other a distance in excess of said average dimensions.
"8. Sound-absorbing means comprising, in combination, thick porous material having high capacity for sound absorption, and a thin, dense, perforated material having less sound-absorbing capacity, the spacing of the openings in said perforated material, as specified herein, bearing such relation to the length of the sound waves passing therethrough as to provide a combined sound-absorbing efficiency as great as that of said high capacity sound-absorbing material.
"9. The combination with a sound-absorbing material, of a thin, sheet metal facing therefor having a multiplicity of small openings therein and supported at its margins, said openings having dimensions several times the thickness of said sheet metal and spaced between edges a distance in excess of said dimensions.
"10. The combination with sound-absorbing material having an efficiency in excess of 70%, of thin, dense, foraminous material having an efficiency less than 25%, forming a facing therefor, the openings in said dense material being spaced, as specified herein, to permit the transmission of sound waves in such manner as to result in an efficiency in the combined materials in excess of that of said sound-absorbing material.
"11. Means for deadening sounds reflected from a hard surface, comprising a layer of sound-absorbing material between the source of sound and said hard surface, and perforated sheet metal adjacent said sound-absorbing material between it and said sound source, the openings in said sheet metal being substantially uniformly distributed over its surface and having a total area less than the unperforated area of said metal.
"12. Sound-absorbing means as in claim 5, in which the area of the individual openings averages from 0.004 to 0.0123 square inches.
"13. Sound-absorbing means as in claim 5, in which said openings have a minimum dimension less than 0.125 inch and are spaced at least about 0.177 inch apart at their minimum distance.
"14. A sound-absorbing structure as in claim 6, in which the openings cover about 0.4% to 35% of total area.
* * * * *
"23. In a building structure, the combination with a wall or ceiling surface of a room, of an exposed foraminous rigid non-sound-absorbing sheet spaced therefrom, a sound-absorbing material between said sheet and said wall or ceiling surface and concealed by the former, and means for supporting said sheet in said spaced relation and adjacent to said surface, the ratio of the exposed area of the sheet to the openings therein being such as to provide a substantially continuous decoratable surface."
17. The expressions such as "thin sheet," "thin stiff member," "thin self-sustaining material," used in the claims, when interpreted by the building art and by reference to the specifications of the patent in suit in which they are qualified by the word "membrane," mean a metal sheet or material of sufficient thickness only to support the sound-absorbing material in place and to maintain a rigid, smooth surface.
18. The phrase occurring in claim 1 and in substantially the same form in claims 3, 5, 12, 13, and 23, "the ratio of the unperforated area of said sheet to the openings therein being such as to expose an apparently substantially continuous surface to the sound waves," has reference to the exposing of the surface of the supporting facing when interpreted in the light of the patent specification and the file wrapper and contents of the Norris applications. Page 72 of the file wrapper of the first Norris application contains subject matter relating to the adoption of this phrase to distinguish over certain prior art cited by the Patent Office, in which a metal retaining member was nearly all cut away, leaving only a few crosspieces to support the sound-absorbing pad.
The term in this phrase "substantially continuous surface" makes these claims indefinite.
19. Claims 8 and 10 recite the sound-absorbing efficiency of the backing material, the facing material, and the efficiency of the composite structure.
The graph, Fig. 14 of the drawings, discussed in the specifications, is illustrative to those skilled in the art of the general characteristics of the patentee's composite structure comprising a sound-absorbing material with a non-sound-absorbing facing of sheet metal. In order to extend the application of this graph to various sound-absorbing materials, various sizes and shapes of perforations and at various sound frequencies, it is necessary to submit the structure to a test in order to ascertain its sound-absorption coefficient.
Standard routine commercial tests to ascertain the absorption characteristic of sound-absorbing panels were established in 1920. Such tests, which utilize a standardized source of tone at definite frequencies and ascertain sound absorption by means of instruments, are for the purpose of more accurately measuring sound-absorbing characteristics of the materials tested than can be done by the human ear, and such tests are not experiments in the sense that they are a trial or observation made to confirm or disprove something doubtful.
20. A test such as has been referred to in the previous finding was made with sheet steel facing, this test exemplifying the absorbing effect of the sound-absorbing material alone and the composite effect of sound-absorbing material and the facing in accordance with the phraseology of claims 8 and 10. While this test was made ex parte by plaintiff's expert, Doctor Sabine, its result was agreed to as reasonable by defendant's expert, Mr. Swan.
This test was made with a sound-absorbent backing of 1 1/2' felt in combination with a perforated sheet steel facing 0.018' thick and perforated with 5/64' holes spaced on centers 0.176' with a ration of perforated area of 15.4 percent.
The test which was made at frequencies from 137 to 2,048 cycles indicated an average absorption coefficient of 75.5 percent for the felt backing alone, and a coefficient of 78 percent with the combined backing and perforated sheet steel facing.
21. Some time between May 31 and June 20, 1927, the patentee Norris, through the Burgess Battery Company, completed the installation of a certain sound-deadening device in the office of Pickands, Brown & Company, of Chicago, Illinois. The type of construction here installed comprised a series of sound-deadening tile.
Each individual tile consisted of a perforated metal sheet bent up at the four edges to form a tile-like, open-faced box. A pad of sound-absorbent material cut to fit was placed in this box and the same was secured to the supporting surfaces by parallel furring strips of sheet metal T-shaped in cross-section which engaged with the turned-up edges of the tile. The metal sheet was approximately 1/32' or slightly less in thickness and the perforations were elongated in shape. The ratio of perforated area to the total area was 29 percent.
The white enameled perforated metal sheets forming the rear surface of plaintiff's physical Exhibit 3 are identical with those used in this installation except they are smaller in size. The installation of this structure at the office of Pickands, Brown & Company establishes the date of reduction to practice of June 20, 1927, for the inventions set forth in claims 2, 6, 7, 9, 11, and 14.
22. There is no satisfactory evidence as to the character or thickness of the material employed for the sound-absorbing pads, and no tests or data have been presented relative to the sound-absorbing efficiency of the combined facing and sound-absorbing material of the Pickands, Brown installation as compared to the bare surface of the sound-absorbing material alone.
There is no evidence as to whether the area of the individual perforations averaged from 0.004 to 0.0123 square inch, or that the openings had a minimum dimension less than 0.125 inch, or that they were spaced apart at least about 0.177 inch.
There is no satisfactory evidence of the date of conception and reduction to practice of the inventions set forth in claims 4, 8, 10, 12, and 13 of the patent in suit earlier than February 25, 1929, the filing date of the application which materialized into the patent in suit.
There is no satisfactory way of determining whether this installation is a reduction to practice of claims, 1, 3, 5, 12, 13, and 23. At a distance of 30 to 40 feet from the white enameled perforated sheets of plaintiff's physical exhibit 3 they form an apparently substantially continuous surface. At a distance of 5 to 10 feet they do not.
The Alleged Infringing Structures
23. There are four types of sound-deadening structures, charged as infringements in this case, each type comprising a backing or sound-absorbing material of either fibrous glass or rock wool combined with felt and provided with a facing of thin, stiff perforated sheet metal. These structures were manufactured for or by and used by the United States Navy.
The details of the four examples as regards the thickness of sound-absorbing material, spacing, and size of perforations, and other details as to the facings are given in the following table:
NOTE--Some parts of this form are wider than one screen. To viewmaterial that exceeds the width of this screen, use the right arrow key. To return to the original screen, use the left arrow key.
Example
Thickness of absorbent
Thickness of facing
Material of facing
Diameter of openings
Distance between centers
Spacing between edges ofperforations
Percentage perforated
1
1.5
0.022
Corrosion-resistant
0.093
0.25
0.157
12.6
steel.
2
2.5
.031
Nickel-copper
.156
.375
.219
15.52
3
3
.0185
Terne plate
.093
.25
.157
12.6
4
2.5
.035
Nickel-copper
.095
.25
.155
11
24. Example 2 as set forth above was installed as a lining for soundproof telephone booths in engine rooms on ships. The remaining examples set forth in the above table were installed and used for lining air ducts on ships through which air was forced to flow at varying velocities by means of power-driven blowers. The noise created in the ducts included sound frequencies of from 37 cycles per second due to the blower motor, up to about 1,800 cycles per second, which was a shrill whistle of the air as it passed through the ducts.
The acoustical problem involved in the sound treatment of a room and a duct are the same.
Examples 1, 3, and 4 were also used for soundproofing portions of access trunks on Navy ships. An access trunk is a square-shaped vertical passageway leading from the main deck down to the engine room and provided with ladders and platforms at various levels. Telephones were installed in the access trunks and the sound-deadening treatment was applied to the walls of the access trunk adjacent the telephone.
25. In all of the installations the perforated metal facing was installed in as large sections or sheets as could be conveniently handled, the sheets being soldered together at their margins. The facing was held in place not at the margins but by means of a series of spaced bolts welded or fixed to the inner surface and projecting through the sound-absorbing material and through the sheet metal facing as shown on the drawing, defendant's exhibit 15, or else by self-threading screws placed at certain intervals through the facing and into L-shaped supporting clips, as shown in defendant's exhibit 16, which is typical of the construction of the telephone booths used in connection with example 2.
In the installation on the Navy ships, all of the perforated facing material was non-corrosive in character and was neither painted nor intended to be painted.
Samples of perforated sheet metal (plaintiff's physical exhibits 36 and 37) are typical respectively of the size and character of the perforations used in the four Government structures, exhibit 36 being substantially typical of examples 1, 3, and 4, and exhibit 37 being typical of example 2.
26. Examples 2 and 4 as given in the tabulation in Finding 23 correspond respectively to the data given in defendant's Exhibits 16 and 15, which are typical of structures installed by and for the defendant between August 31, 1938, and July 7, 1939, and used by the defendant during that period.
27. Claims in suit 1, 3, 5, 12, 13, and 23, which define the perforated facing as "apparently substantially continuous" or to "substantially conceal the sound-absorbing material" or to provide "a substantially continuous decoratable surface," are definite by virtue of this phraseology, and the application of their phraseology is uncertain when applied to the perforated facings used by the defendant and substantially exemplified by plaintiff's physical exhibits 36 and 37.
28. Claim 9 of the patent in suit specifies that the thin sheet metal facing is supported "at its margins." In the Government structures the individual sheets forming the thin metal perforated facings are soldered together to form an integral surface, and this is held in place by bolts or screws, the heads of which protrude through or are upon the exterior surface of the facing.
The phraseology of this claim does not apply to the Government structures.
29. Claim 8 describes the Norris structure in terms of sound-absorbing efficiency and defines the invention as one in which the combination of the backing or sound-absorbing material with the sheet metal facing has an absorbing efficiency as great as that of the sound-absorbing material alone. It prescribes that the spacing between the openings in the facing depends upon the length of the sound wave passing through it.
Claim 10 also defines the invention in terms of efficiency, setting forth that the efficiency of the combined materials, i.e., the backing and the facing, is in excess of the sound-absorbing or backing material alone.
Plaintiff's expert made two comparative ex parte tests in connection with the sound absorbing material used by the defendant and perforated metal facing similar to plaintiff's exhibits 36 and 37, which substantially exemplify the facings used by defendant. The results of these tests were agreed to as reasonable by defendant's expert, both tests ascertaining the average coefficient of absorption at frequencies from 137 cycles to 2,048 cycles, inclusive. The first test exemplified example 1 of the Government structure, the perforated facing having the same values as tabulated in Finding 23. The results of this test showed a sound-absorbing efficiency of the backing alone of 88 percent and of the backing in combination with the facing of 85.7 percent.
The second test exemplified example of the Government structure as set forth in the tabulation in Finding 23. In this case the sound-absorbing efficiency of the backing alone was 93.7 percent and that of the backing in combination with the perforated facing 91.9 percent.
In neither instance was the efficiency of the combined backing material and the perforated facing equal to or in excess of the efficiency of the backing material alone. The phraseology of claims 8 and 10 does not apply to the Government structure.
30. The phraseology of claims in suit 2, 3, 4, 6, 7, 11, and 14 is applicable to the structures used by the Government.
The following patents were issued on application filed in the United States Patent Office on the dates indicated:
U.S. Patent to Delaney, No. 1,660,745, issued February 28, 1928, on an application filed June 30, 1926.
U.S. Patent to Rosenblatt, No. 1,751,249, issued March 18, 1930, on an application filed June 23, 1927.
32. All the patents listed as prior art in the above findings, with the exception of Rosenblatt and the British patent to Stevens, are of record in the Patent Office file of the application which matured into the patent in suit.
On page 8 of an amendment filed June 4, 1929, with the Examiner of the Patent Office having charge of this application, the following statement appears:
"As a matter of record, the prior art over which the foregoing claims have been allowed is hereby copied into this application from the earlier application 212,265.
* * * * *
"Mazer, 1,483,365.
"Trader, 1,554,179.
"Delaney, 1,660,745.
* * * * *
"Dillon, 1,385,741.
"Trader, 1,554,180."
33. United States patent to Dillon, 1,385,741, discloses a structure referred to as a sound deadener for building structures. In the first form of construction disclosed by Dillon a sheet of unwoven, sound-absorbing material such as felt is secured to the walls or ceilings by means of wooden strips and nails. This is then covered by a woven textile fabric membrane spaced from the unwoven material by means of cleats, the fabric membrane being perforated.
This structure is stated to provide a chamber in which the sound waves, after being broken by passing through the perforated fabric membrane, are retained or absorbed or passed through the unwoven material.
In a modification of the Dillon structure the space between the woven fabric and the sound-absorbing fabric is omitted, the specification stating with respect to this modification that "the woven membrane is arranged in intimate contact with the unwoven material."
With respect to the character, size, and spacing of the perforations, the specification states as follows:
"It is obvious that the perforations may be of any shape or form and spaced apart regularly or irregularly according to the desired design or requirement."
This disclosure does not instruct those skilled in the art as to any dimensions of the structure or any size or spacing of the perforations in the fabric membrane nor does it disclose or suggest to those skilled in the art the use of a perforated metal facing or a facing that is of self-sustaining and non-sound-absorbing material.
34. United States patent to Mazer, 1,483,365, discloses a building block constructed for the purpose of absorbing sound. The specification discloses a block of plastic composition and suggests such materials as "gypsum, sand and cement mixtures, sand and lime mixtures, and the like." Such a block is constructed with a relatively thick facing which is provided with a number of apertures penetrating in from the face, these apertures being defined in the specification as "long, narrow apertures, the length of which is considerably greater than the width of the openings." Figs. 2 and 4 of the patent are reproduced herewith, Fig. 2 illustrating the alleged sound-absorbing effect of these apertures.
With reference to Fig. 2, the specification teaches those skilled in the art that if a sound wave "S" strikes one of the tube-like apertures at any angle it undergoes a large number of impacts against the sides of the aperture, with partial absorption at each successive impact, so that when the sound travels into the aperture and then out of it, as indicated by Fig. 2, the sound may be entirely absorbed in the relatively long walls of the apertures.
Fig. 4 shows a modification in which the central portion of the block is filled with felt or some other highly sound-absorbing material.
(Image Omitted)
The structure and method of sound-absorption, as disclosed by Mazer, differ from the Norris patent in suit, in that Mazer teaches the art a principle of sound absorption in long narrow apertures formed in a block having a thick facing for this purpose. As stated, this is also used in connection with sound-absorbing material in the middle of the block.
The Mazer specification gives no dimensions and does not disclose a thin metal perforated facing or a thin nonsound-absorbent facing. On the contrary, it teaches those skilled in the art to use a facing of sufficient thickness to provide for sound absorption in the facing itself.
35. United States patent to Trader, 1,554,179, discloses a sound absorbing material operating on the same principles of sound-absorption as disclosed in the Mazer patent referred to in the previous finding. The material disclosed in the specification is referred to as sound-absorbing material either in the form of blocks or sheets, characterized by extreme porosity and approximately 1"' in thickness. These sheets have perforations extending either entirely through them as shown in Fig. 1 of the patent, or partially through, as shown in Fig. 5. The function of these perforations is set forth as follows:
"By the provision of suitable apertures, cavities, recesses or the like, in the surface of the material exposed to the sound waves, and into which they are projected either directly or indirectly, I secure the result that the entering waves will be pocketed or smoothered [sic] and thus eliminated, due to the fact that the sound waves striking the surface of the wall or ceiling covered with sound absorbing material prepared according to my invention, are almost entirely isolated or confined, within such recesses or cavities, and to the further fact that the provision of these cavities, recesses or the like which can be entered by the sound waves, provide a much larger area of sound absorbing surface that the material heretofore employed, which is characterized by its cellular or porous structure."
This patent discloses to the art a sound-absorbing material possessing perforations or recesses extending into or through the sound-absorber, in which perforations the sound waves are dissipated. This patent does not disclose nor suggest a combination of a backing of sound-absorbing material with a thin perforated facing of metal or non-sound-absorbing material.
36. United States patent to Trader, 1,554,180, discloses the same sound-absorbing construction as referred to in the previous Trader patent, the illustration being substantially the same. This second Trader patent, however, relates to the use of the sound-absorbing apertures in the specific type of material known as "Celotex" or "Insulite." The specification discusses the porous, fibrous nature of "Celotex" and "Insulite" and indicates that each of these materials is made from wood pulp, the surface pores of which when dry are more or less closed due to films or skins caused by the pressure to which the pulp is subjected during the process of squeezing out the surplus water.
The specification indicates to those skilled in the art that the perforations, either made entirely through the material or partially into it, permit the sound waves to readily pass into the interior spaces of the fibrous structure in such a manner as to render impossible further reflection back into the room.
The disclosure of this patent is similar to that of the other Trader patent in that it merely discloses a sound-absorbing material possessing perforations. It does not disclose a combination of a backing of sound-absorbing material with a thin perforated metal or similar non-sound-absorbing facing.
37. United States patent to Delaney, 1,660,745, discloses an acoustic building block or slab intended to operate on the same principle of sound absorption as disclosed in the Mazer and Trader patents referred to in the previous findings. Fig. 3 of the patent, which is reproduced herewith, is illustrative of the Delaney construction, this figure illustrating a relatively thick facing provided with long, narrow apertures. The specification states with respect to the construction of the shell and the functioning of the perforations that
(Image Omitted)
"The material for forming the shell is preferably of a strong porous nature and the perforations b in the facing give such facing a high sound-absorbing value and may yet be made to receive any ornamentation or to be made smooth and yet attractive as a finish."
The interior of the shell is stated to be filled with sound-absorbing material such as "asbestos wool, loose, pumice, hair, cork, or substances having like sound-absorbing properties."
The specification contains a statement that the shell
" * * * may be made of any suitable material or materials such for instance as plaster, cement, fibrous material, wood, terra cotta, or in some instances, metal."
The specification, however, fails to teach those skilled in the art how a nonsound-absorbing material such as metal could be used for the relatively thick facing disclosed, and the reference to metal is inconsistent with the method of sound absorption indicated in connection with the preferred form, with reference to which it is stated that the facing has "a high sound-absorbing value."
This disclosure does not teach the art that a thin metallic non-sound-absorbing facing, when suitably perforated in accordance with sound-wave lengths to be absorbed and used in combination with a backing of sound-absorbing material, will permit a sound absorption substantially identical in efficiency with the sound-absorbing backing material.
38. United States patent to Rosenblatt, No. 1,751,249, discloses a sound treatment consisting of a sound-absorbing element such as felt upon which a membrane is placed by means of a layer of paste or glue. The patent does not state of what the membrane is made. A coating of paint, enamel, or plaster is then applied to the outer surface of the membrane, it being stated that the final coating alone is disadvantageous from the standpoint of maximum absorption, although usually necessary from an ornamental standpoint.
The specification then indicates that a multiplicity of minute pores or openings is formed through the coating or membrane so that the sound waves may reach the sound-absorbing material. It is suggested that such perforations can be made by such mechanical means as a roller studded with a multiplicity of sharp, thin points, the specification suggesting the use of points approximately one-hundredth of an inch in diameter and spaced on centers one thirty-second of an inch apart. This patent discloses a sound-absorbing material covered by a perforater facing, one constituent of which is plaster or enamel.
This patent was granted on an application filed in the United States Patent Office on June 23, 1927, which date is subsequent to the Burgess Battery installation in the office of Pickands, Brown & Company of Chicago, Illinois, as set forth in Finding 21.
39. British patent to Stevens, No. 4,843, of 1887 relates to a gas engine and a muffler or silencer therefor. The muffler is shown in two forms. Fig. 6, which is pertinent to the present issue, discloses a silencing arrangement comprising an exhaust pipe or duct. The interior walls of this duct are lined with what the patentee states to be "incombustible sound-damping material, for instance, asbestos, so that the noise produced by the expulsion of the exhaust gases is damped thereby." This sound-damping material is held in place by a facing of sieve-like perforated sheet metal.
The Stevens patent discloses a backing of sound-absorbing material held in place by a thin, stiff, self-sustaining perforated facing of non-sound-absorbing material.
This disclosure, with the exception that the size and spacing of the perforations of the perforated metal sheet are not specified, is analogous with both the construction suggested by the patent in suit and the Government structures alleged to infringe, especially where used as sound-deadening lining for air ducts.
40. The publication "The Dynamical Theory of Sound" published in 1925 by Horace Lamb beings a discussion on page 248 termed "Transmission of Sound by an Aperture." The article refers to the transmission of sound waves by an aperture in a thin screen where dimensions of the aperture are small compared with the wave-length, and gives a mathematical formula for the determination of the amount of sound energy transmitted through the opening.
The publication next discusses an aperture in the shape of a long narrow slit whose breadth is small compared with the wave-length of the sound, and gives a second formula for determining the energy to be transmitted, this formula including as algebraic expressions both the minimum dimension of the opening and the intervening portion of the screen. By the use of such formula those skilled in the art can calculate in advance the desired minimum dimensions of apertures the desired minimum dimensions of apertures and their spacing for passing any given percentage of sound energy through the screen at a given wave-length.
The publication gives as a numerical example of the use of this formula a specific instance in which the wave-length of the sound is ten times the interval between the centers of the successive apertures. With such spacing, and if the apertures form only 10 percent of the whole area of the screen, 88 percent of the sound will pass through. Application of this example to a sound frequency of 512 cycles which has a wave-length of a little over two feet, shows that with a width of aperture of 0.2"' and a distance between apertures of two inches, 88 percent of the sound energy will pass through the screen. If this example is applied to a sound frequency of double this value, or 1,024 cycles, and the same interval of space as suggested by the formula is maintained, the distance between the apertures would become about one inch.
The Lamb article teaches those skilled in the art the same relationship between sound frequency and spacing between apertures as is set forth by the patent in suit, in that the interval between the centers of successive apertures decreases as the sound frequency increases in order to maintain the same efficiency of sound transmission through the screen.
41. Sound treatment of rooms and enclosed spaces and the general effect of sound-absorbing materials were known to those skilled in the art more than two years prior to the filing date of the original Norris application.
Claims in suit of the Norris patent are directed to a structure in which such sound-absorbing material is held in place by a thin, stiff, self-sustaining perforated facing of non-sound-absorbing material. Such combination is shown in the British patent to Stevens, in which, similar to the preferred embodiment of the patent in suit, a perforated metal sheet is used to hold the sound-absorbing material in place.
Claims 1, 3, 5, 12, 13, and 23, which define the facing as "apparently substantially continuous" or to "substantially conceal the sound-absorbing material" or to provide "a substantially continuous decoratable surface," are uncertain and indefinite as to the size and spacing of the perforations they are intended to cover. These claims are invalid.
42. The subject matter of claims in suit 2, 4, 6, 7, 11, and 14 differs from the disclosure of the British patent to Stevens only by a selection of particular relative dimensions and spacing of the perforations and the ratio of perforated to nonperforated area.
Those skilled in the art and desiring to make use of the thin perforated sheet metal of Stevens in holding the sound-absorbing material in place, could use the Lamb publication to design the apertures and the spacing between them in such manner as to transmit a maximum portion of the sound energy through the sheet metal facing for any given wave-length. If desired, the perforated area of 10 percent mentioned in the Lamb publication could be used, which area is stated to pass 88 percent of the sound energy.
The phraseology of claims 8, 9, and 10 is not applicable to the Government structures and these claims are not infringed.
43. The claims of the Norris patent in suit are anticipated by and define no patentable invention over the prior art listed in finding 31. [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] [Copyrighted Material Omitted] Daniel V. Mahoney, of New York City (Pennie, Davis, Marvin & Edmonds, of New York City, on the brief), for plaintiff.
T.H. Brown, of Washington, D.C., and Francis M. Shea, Asst. Atty. Gen. (C.P. Goepel, of New York City, on the brief), for defendant.
Before WHALEY, Chief Justice, and LITTLETON, WHITAKER, JONES, and MADDEN, Judges.
WHITAKER, Judge.
Plaintiff, the assignee of the Norris patent, 1,726,500, sues to recover damages for its alleged infringement. The defendant defends upon the ground, among others, that the alleged invention was anticipated by prior art and knowledge, and, therefore, was lacking in patentable novelty. The patent is on sound-deadening construction. It consists, briefly, of a sound-absorbing backing, such as felt or wool, covered and held in place by a thin membrane of sheet steel, tin, veneered wood, or similar sound-reflecting material, punctured at intervals to permit the passage of the sound waves through the membrane into the sound-absorbing backing.
Most of the claims in suit are indefinite as to the size and spacing of the holes in the membrane. For instance, claim 1 says that "the ratio of the unperforated area of said sheet to the openings therein being such as to expose an apparently substantially continuous surface to the sound waves." Claims 5 and 23 are substantially to the same effect. Claim 2 says only that the dimensions of the holes should be less than the distance between the edges thereof. Claim 3 says the holes should be small enough to conceal the sound-absorbing material. Claim 6 says the size of the holes should be greater than the thickness of the membrane. Claim 7 is a combination of claims 6 and 2. Claim 9 is also a combination of claims 6 and 2, but adds the statement that the membrane is supported at its margins. Claim 12 specifies the size of the holes at from 0.004 square inch to 0.0123 square inch. Claim 13 says the holes should have a minimum dimension less than 0.125 inch and should be at least 0.177 inch apart.
Claim 11 says that the total area of the holes should be less than the unperforated part of the membrane. Claim 14 says the holes should cover from 0.4 percent to 35 percent of the area of the membrane. Claim 4 says the holes should cover not more than 16 percent of the area. Claim 8 says the spacing of the holes should bear "such relation to the length of the sound waves passing therethrough as to provide a combined sound-absorbing efficiency as great as that of said high capacity sound-absorbing material."
It will be noted that the size of the holes and the spacing between them varies greatly, the total area to be perforated varying from 0.4 to 1 percent to 49 percent. The only guide found in the claims to determine the size and number of the holes is that they should be of a size greater than the thickness of the membrane, that the space between them should be greater than their size and that the number of them should bear that relation to the sound waves passing through them which gives as great an efficiency to the backing when covered by the perforated membrane as it had without it. The size of the holes and the space between them that would give equal efficiency is not stated in the claims; but in the specification it was said "that the spacing of the holes should be determined by the pitch of the sound which is absorbed. The lower the pitch of the sound, that is, the smaller the number of double vibrations per second and the longer the wave length, the greater may be the distance between the holes to secure the same absorption."
We have, then, a patent consisting of a sound-absorbing backing covered with a thin sound-reflecting material of wood or metal to conceal the backing and to hold it in place, with holes in it of a size and spaced apart at a distance dependent on the pitch of the sound to be absorbed. The graph in the specifications shows that maximum absorption of sound waves of 512 double vibrations per second is obtained with holes every square inch. When the pitch of the sound is doubled there may be two holes per square inch, and when doubled again, four holes per square inch, etc.
The defendant says all this was anticipated by the prior art and knowledge. It points first to the Dillon patent No. 1,385,741. The principle of this patent and the one in suit is the same, except (1) the covering of the backing in the Dillon patent is a woven textile membrane, whereas in the Norris patent wood or metal is used; and (2) Dillon does not say he spaces his perforations according to the pitch of the sound to be absorbed.
The Mazer, Trader and Delaney patents all use a sound-absorbing backing, but they differ from the Norris patent in that the facing is thick and itself is designed to absorb some of the sound. This is accomplished by long apertures through the facing, the theory being that the sound waves bounce back and forth down the sides of the aperture, which is said to have the effect of deadening the sound. This is not a feature of the Norris patent.
As stated, one difference between the patent in suit and the Dillon patent was the use by the patentee of a thin metallic or wooden membrane, instead of the textile membrane used by Dillon. However, in the British patent issued to Stevens perforated sheet metal was used to hold the sound-deadening material in place. This patent clearly disclosed the practicability of using metal instead of a woven textile fabric as the facing for the sound-absorbing material. That the patent in which this disclosure appeared is a foreign patent is immaterial under section 35 U.S.C.A. § 31. In re Cross, 62 F.2d 182, 20 C.C.P.A., Patents, 710; Becket v. Coe, 69 App.D.C. 51, 98 F.2d 332.
The Norris patent differs from the Stevens patent only in that the latter says nothing about the size of the holes nor the spacing between them.
No patent referred to by defendant contains what seems to us to be the distinctive feature of the Norris patent, to wit, the spacing of the holes in accordance with the wave length of the sound to be absorbed. This, however, was a principle known in the art. Lamb in his book on "The Dynamical Theory of Sound" treats of the transmission of sound through apertures. He sets forth a formula for computing the sound transmission through apertures, depending on the size of the openings, the spacing between the openings, and the wave length of the sound to be absorbed.
This is the only feature of the Norris patent which in our opinion differs from prior patents, and it had been anticipated by the Lamb publication. See Freyn Engineering Co. v. Coe, 65 App.D.C. 9, 79 F.2d 134.
In the case of Burgess Laboratories, Inc., v. Coast Insulating Corp., 27 F.Supp. 956, the District Court held claim 4 valid, but it does not appear from a reading of the opinion that the Stevens patent and the Lamb publication were relied on in that case. In our opinion this patent and this publication, taken in conjunction with the Dillon patent, clearly anticipate the patent in suit.
We are of opinion the Norris patent is invalid for lack of novelty. It is, therefore, unnecessary for us to discuss whether or not the defendant's construction infringes the Norris disclosure.
Plaintiff's petition will be dismissed. It is so ordered.
WHALEY, Chief Justice, and MADDEN, and LITTLETON, Judges, concur.
JONES, Judge, took no part in the decision of this case.