The opinion of the court was delivered by: CAMPBELL
CAMPBELL, District Judge.
This suit is brought by the plaintiff for the alleged infringement by the defendant of (1) patent No. 1,957,237, issued to Walter L. Upson, assignor, to General Electric Company, for Fan Blade, granted May 1, 1934, on application filed January 20, 1932; (2) design patent No. 89,076, issued to Joseph W. Gosling, assignor, to General Electric Company, for design for an electric fan, granted January 24, 1933, on an application filed December 1, 1932.
The title of the plaintiff to the patents in suit is admitted and the sale by defendant, Parr Electric Company, Inc., of the types of fans charged to infringe, within this district, subsequent to the granting of the patents in suit, and prior to the commencement of this suit, is also admitted.
The alleged infringing fans were manufactured by the Emerson Electric Manufacturing Company of St. Louis, and that company is defending this suit in behalf of Parr Electric Company, Inc., its customer, and references hereinafter made to "defendant" are to be understood as referring to the Emerson Electric Manufacturing Company, unless otherwise indicated.
With reference to the type of fans known as the "Silver Swan" defendant is charged with infringing claims 8, 9, and 17 of the Upson patent, and with infringement of the Gosling design patent.
With reference to the type of fans known as the "Lindberg," the defendant is charged with infringing claims 7 and 14 of the Upson patent; but plaintiff in this suit relies only on claim 7, and does not think that claim 14 adds anything of importance to claim 7.
The original bill of complaint was filed in December, 1934, and was directed against the "Silver Swan" fan. Subsequently the Emerson Electric Manufacturing Company began to manufacture, and the Parr Electric Company, Inc., to sell, fans of the "Lindberg" type, and in September, 1935, plaintiff filed a supplemental bill directed against this type of fan.
I will discuss the case with reference to each of the said patents in the order hereinbefore named.
The Upson Patent 1,957,237.
The patent says: "My invention relates to fans and more particularly to fan blades." Page 1, lines 1 and 2.
In the following paragraph the patent mentions many types of fans to which the present invention is directed; viz., theater auditorium fans, air conditioning apparatus fans, blowers and air circulating fans, home fans, furnace fans, ventilating fans for winter as well as summer, kitchen fans, and fans used with electric refrigerators.
Although it is true that the "Silver Swan" fan and the "Lindberg" fan are desk fans, the fan of the Upson patent in suit as has been shown was not limited to desk fans, and this appears from the testimony of plaintiff's witness Peters. This further appears from the fact that the plaintiff company has licensed two companies under the Upson patent in suit; one to use the patent on "free air fans," and both specifically to use the Upson patent in suit in fans "other than free air fans." Obviously the plaintiff intended to have the patent used for every type of fan.
As broad as is the patent, so broad may be the prior art cited against it from the same fields.
The patent then proceeds in the next paragraph to state the object of the invention as follows: "The object of my invention is to provide improved blades for fans which will make them comparatively quiet in operation and yet make them comparable in the velocity imparted to the air, the velocity distribution, and the efficiency of operation with standard fans." Page 1, lines 38-43.
The fan is shown as having three wide blades, which, together, occupy substantially the full desk area of the fan.
In Fig. 1 the arrow indicates the direction in which the fan is to rotate; 16 indicates the leading edges of the blades, 18 the peripheral edges, and 17 trailing edges.
Different views are shown in Figs. 1-4, inclusive, of a fan of this wide bladed type in which the surface of the blade is so curved that it has a "pitch" which increases in the direction from the outer periphery to the hub of the fan, and in which the trailing edge is turned up.
Fig. 5 shows a modified form in which the surface of the blade is a plane surface to a point near the trailing edge, but which is turned up near the trailing edge. As explained in the patent, the "pitch" of a blade with such a plane surface increased from the leading edge to the median line of the blade, and then decreases up to the point where the blade is turned up, when it again increases.
With reference to the form shown in Fig. 5, the patentee says: "The operation of this fan compares favorably with the operation of the preferred form of blade as illustrated in Fig. 2 and its formation is somewhat less expensive than the preferred form of blade." Page 2, lines 46-50.
A third form of surface configuration is shown in Fig. 6, in which the curvature of the blade is such that there is an increasing pitch over the whole of its surface from leading edge to trailing edge; the surface of the leading part of the blade being a plane, and the whole trailing end being curved in order to "provide a surface of increasing pitch for this part of the blade" as well as for the leading end of the blade.
The patent speaking of reduction of noise says: "The fan is generally indicated by the numeral 10 and comprises three blades 11, 12 and 13 secured to a hub 14 by means of screws 15. The amount of noise produced by a fan increases with the number of blades providing other features of the fan remain the same. If one blade were used, and its area made sufficiently large to move a relatively large quantity of air then its axial length would of necessity be too long. This would also be true of a fan with two blades. I prefer to use three blades for fans run at speeds between 1100 and 1600 R.P.M. but a greater number of blades may be desirable when it is possible to run the fan at a lower speed. The decrease in speed offsets the increase in noise which would be occasioned by the greater number of blades." Page 1, lines 59-75.
The patent further says: "As best indicated in Fig. 1 the trailing end of one blade overlaps the leading end of the following blade. In other words looking at the face of the fan, the leading end of one blade extends behind the trailing end of the blade preceding it in the direction of the rotation of the fan. Thus the trailing end of one blade shields the leading end of the following blade which assists in reducing the noise of the entrance of air into the fan. The overlapping blades also makes it certain that the maximum disc area of the fan is being utilized. By thus utilizing the full disc area of the fan it is possible to considerably reduce the diameter of the fan and at the same time move a large quantity of air. The reduction in the diameter of the fan is extremely important in the noise reduction of the fan because it reduces the peripheral velocity of the tip of the blades. The high peripheral velocity of the tip is the source of much of the noise of many fans." Page 2, lines 130-150.
The patent also specifies: "The fan blades are not extended to 90 degrees ahead of the radius 0-0' because it would make the fan too long in its axial length. It has been found that it is quite satisfactory to extend the blade at the periphery to about 75 degrees ahead of the radius 0-0' where the pitch is sufficiently low so that the air may be picked up without noise." Page 2, lines 88-95.
Claim 1 (which is not in suit) claims specifically this feature of a leading end 75 degrees long and a trailing end 60 degrees long. No such limitation as to width is found in any of the claims in suit, and its absence indicates, under the claim differentiation doctrine, that they were not intended to be so limited. Smith v. Snow, 294 U.S. 1, 55 S. Ct. 279, 79 L. Ed. 721.
The number of blades determine the blade width when it is coupled with the requirement that the blades overlap.
The only limitation as to number that I find expressed in the patent is that the number of blades cannot practically be less than three.
The requirement of the claim in suit that the fan shall have a total blade area "substantially equal to the disc area" is found in the Breezo fan (Exhibit Y) just as well as in the three-bladed fan shown in the patent in suit.
A claim reciting "numerous" fan blades is not limited to any especial number. Sirocco Engineering Co. v. B.F. Sturtevant Co. (C.C.A.) 220 F. 137.
Of course it is generally true, and this was well known and not a discovery by Upson, that the "amount of noise produced by a fan increases with the number of blades providing other features remain the same." Nor was it a discovery of Upson that when the fan could be run at a lower speed the decrease in speed would counteract the increase in noise occasioned by the greater number of blades.
The blades are planes or modified planes, and if it be assumed that the blade is planar throughout its entire area, then a series of arcs may be drawn about the axis of rotation as a center, with the result as shown in Fig. 3 of the patent in suit. Each of these arcs is said to represent the path of travel of a particle of air across the blade of a fan as it rotates, and the pitches of a fan blade are always to be measured on these arcs.
In a planar blade there is a certain central radius at which the pitch is maximum. Ahead of this central radius and approaching the leading edge, the pitch decreases until, if the blade extends forward 90 degrees from the central radius, the pitch reaches 0. Likewise, the pitch decreases back of the central radius toward the trailing edge until, at 90 degrees back of the central radius, it reaches 0. Whatever the pitch is at the central radius where the surface of the blade is a plane, and whatever is the width of the blade, the pitch will gradually increase from the leading edge to a maximum at the central radius, and back of the central radius it will decrease toward the trailing edge.
By his adoption of this well-known fact, the patentee was permitted to gradually put the air in motion and to accelerate it as far back as the central radius, and to compensate for the decrease in pitch back of the central radius, the patentee proposed two well-known remedies. The first, the less desirable but cheaper remedy, was to turn up the trailing edge, a modification of Fig. 5 in which the air is accelerated to the central radius, and then as far back as the blade is concerned, it is decelerated by the decreasing pitch until it reaches the turned-up portion immediately adjacent the trailing edge, which gives the air a final impulse with considerable acceleration, but not a smooth motion. The second remedy is shown in Fig. 6, and consists of a gradual curving up of the trailing end throughout its extent from the central radius back until at the trailing edge the blade has the greatest curvature. This blade may have gradually increasing pitch throughout its extent since, inherently, the planar leading end has this characteristic.
The blades of Fig. 5 and Fig. 6, in which we are interested, have planar leading ends and differ only in their trailing ends. Only Fig. 6 has constantly increasing pitch throughout.
The edge contours are the same in both types of blades. They consist of the leading edge, the peripheral edge, and the trailing edge. The patentee limits his description of the trailing edge to substantially a straight line merely rounded off towards the periphery, but he does have a trailing edge as distinguished from his peripheral edge.
The patentee described the leading edge 16 as concave and extending forward progressively from the hub to the outer periphery of the blade, and describes its object as twofold, so that the initial axial displacement of the air is constant, and so that more air may be picked up. As I read the specification, the concave curve must be such that the initial axial displacement of air is constant.
The peripheral edge need not be described as it appears only in claim 14, which is not now relied upon by plaintiff. It is sufficient to say that there is a distinct demarcation between the peripheral edge 18 and the leading edge 16.
The patent in suit summarizes the features of the invention as follows: "From the foregoing it may be seen that a blade for fans is provided which reduces the noise of their operation by causing particles of air to travel along a plane surface which is a surface of gradually increasing pitch for the leading part of the blade, by utilizing the full disc area of the fan thus reducing the diameter of the fan for a given output to decrease the peripheral speed of the blades, and by shaping the leading edges of the blades to reduce the noise of the pick-up of the air." Page 3, lines 9-19.
The features so explained in the patent are quite different from plaintiff's present position that the patent in suit covers the use for desk fans of six or less wide blades.
I can find no basis in the Upson patent in suit for limiting the number of blades to six. Nowhere in the patent is the number six mentioned as the number to which the blades are limited. The Upson patent in suit does not definitely limit the number of blades. In the drawings three blades are shown, and in all the commercial fans involved of both plaintiff and defendant, four blades are used. As three blades are shown and four are used, why limit the number to six? They are not so limited by the claims in suit. I find no support in the drawings for any theory that the number of blades must be limited to six so that the width is at least as great as the radial length. The specific limitation of claim 1 requiring the leading end to be 75 degrees wide and the trailing end about 60 degrees wide does not in this case support the theory that the number of blades is limited to six, as that claim is directed to a threebladed fan. Claim 1 is not in suit, and no such limitation as to width is found in any of the claims in suit. The quotation from the patent, page 2, line 136, does not support the theory of the limitation of the blades to six in number. As I understand that quotation, it means that by using the full disc area with a small fan as much air can be moved as with a large fan not employing the full disc area. That certainly does not limit the number of blades to six, because, if delivery is increased by full disc area, it would be just as true with eight blades as six, if they be made wide enough to overlap.
Plaintiff's further contention is that the Upson patent in suit teaches that to have a quiet fan, you must avoid separation. Nowhere in the Upson patent in suit do I find any mention of separation.
Certainly it is not claimed in any of the claims in suit, and I do not see how by that theory the number or width of the blades can be limited, when there is no such limitation in the patent in suit.
Of course, the patentee need not know why his invention obtains a certain result, but he must have described the structure which he claims to have invented, and if wide blades of a limited number constituted a part of the structure which he claimed to have invented, the patent should have so stated and claimed them.
He did not, and he did not limit his invention to three blades or six blades, but said that any number of blades could be used. It does not seem to me that any limitation to the number of blades nor to wide blades can be read into the claims in suit.All that I can find that Upson required as to the width of ...