Norac Systems International Inc. v. Prairie Systems And Equipment Ltd.

Norac Systems International Inc. v. Prairie Systems And Equipment Ltd.
Court (s) Database
Federal Court Decisions
Date
2002-03-25
Neutral citation
2002 FCT 337
File numbers
T-1973-95
Notes
Digest
Decision Content
Date: 20020325
Docket: T-1973-95
Neutral Citation: 2002 FCT 337
Ottawa, Ontario, this 25th day of March 2002
PRESENT: THE HONOURABLE MR. JUSTICE PELLETIER
BETWEEN:
NORAC SYSTEMS INTERNATIONAL INC.
Plaintiff
- and -
PRAIRIE SYSTEMS AND EQUIPMENT LTD.
Defendant
REASONS FOR ORDER AND ORDER
[1] Norac Systems International Inc. (the plaintiff) is the assignee of a patent for a mobile weighing system, designed to be used to accurately weigh loads carried on a truck or trailer. Prairie Systems and Equipment Ltd.(the defendant) has also developed a system for doing the very same thing. The plaintiff says that the claims of the patent can be read directly upon the defendant's device, thus establishing infringement. The defendant says that its system does not contain essential elements of the patent and as a result does not infringe the patent. In any event, the defendant says that the invention, as described in the patent, lacks utility and inventiveness so that the patent is invalid. Thus is the issue joined.
[2] The problem which the invention is intended to solve is that of weighing loads on mobile platforms such as trucks or trailers which are often in non-level conditions. The difficulty arises from the fact that gravity acts at right angles to the surface of the earth (the vertical axis) so that if the weight of the load is not applied to the weighing device in this axis, the measured weight will be in error. The market for both parties' products is truck mounted agricultural delivery systems for commodities such as anhydrous ammonia where loads must be weighed in the field, usually without the benefit of perfectly flat terrain. The challenge was to accurately weigh the load even when the supporting platform was not parallel to the ground.
[3] The patent was issued to William Strelioff, the inventor, by the Canadian Patent Office as patent no. 2,096,761 on July 4, 1995. It was subsequently assigned by Mr. Strelioff to Norac, a corporation which he now controls. Claim No. 1 of the patent claims a mobile weighing system consisting of a load support frame, a truck or trailer frame below the load support frame and a plurality of weighing cells. Claim no. 2 describes a weighing system according to claim one involving a linkage system. Claim no. 3 claims a weighing system according to Claim 2 comprising 3 weighing cells. Claim no. 4 describes a weighing system according to claim 3 comprising a lock down mechanism for securing the load when the lifting mechanisms in the weighing cell are not in use. Claim no. 5 describes a weighing system according to claim no.4 in which the lock down mechanism is more particularly described. It can be seen that claims 2 to 5 are dependent claims which derive from claim no. 1.
[4] The two claims in issue in this action are claims 6 and 7. Claim no. 6 is an independent claims which describes a weighing cell and is reproduced below:
A weighing cell for use in a mobile weighing system, comprising a lifting mechanism having an extended and a rest position, a vertically disposed tension load cell which produces an output correlated to a tension load thereon and a linkage assembly whereby said linkage assembly couples said lifting mechanism and said load cell to cause an upward force on a first end of said load cell when said lifting mechanism is in an extended position, the second end of said load cell being configured for coupling to a load support frame such that said load support frame may be suspended by a plurality of said load cells when the lifting mechanisms thereof are in extended positions.
[5] Claim no. 7 claims a weighing cell according to claim no. 6 in which the linkage assembly is more particularly described as follows:
A weighing cell according to claim 6 wherein said linkage assembly comprises a stationary bar and a cross-arm pivotally attached thereto and said first end of said load cell is pivotally attached to said cross-arm whereby said load cell remains vertically disposed when said lifting mechanism is in an extended position
[6] Claim no. 8 describes a weighing cell according to claim no. 7 and a lock down mechanism in such a weighing cell. The final claim is claim no. 9 which describes a method of weighing a load on a truck deck or trailer comprising five steps, one of which consists in mounting a plurality of weighing cells according to claim 3 in relation to a load support frame. To that extent, claim 9 depends on claim 3 and ultimately on claim no. 1.
[7] The basic principle of the invention is to pick up the load to be weighed using 3 weigh cells, suspend it so that it can hang vertically and weigh it while it is suspended. Each weigh cell includes a hydraulic cylinder the end which is attached a cross-arm whose other end is pivotally attached to a stationary bar. The extension of the hydraulic cylinder causes one end of the cross-arm to rotate on its pivot while the other rises, following the hydraulic cylinder. One end of an S-type tension load cell is pivotally attached to the cross arm while the other is attached to the load frame to which the load is attached e.g. the tank containing the product to be sold. When the cylinder is extended, the cross arm moves upwards and as it does, the tension load cell pulls the load frame from its resting position on the truck frame to a point where it is suspended by the tension load cell. The load cell is pivotally attached to both the cross arm and the load frame so as to hang perpendicularly to the ground while suspending the load. There are three such weigh cells on a truck or trailer deck so that when all three are activated at once, the entire load is suspended from the 3 load cells whose combined output indicates the weight of the load.
[8] The defendant's device also weighs loads on a truck or trailer deck. The defendant's device consists of two relatively narrow modules. A module is placed on each side of the truck or trailer deck and is more or less the length of the load container e.g. the anhydrous ammonia tank. Each module has a top plate to which the load is fastened. At each end of each module is a weigh cell assembly. It includes a hydraulic cylinder which is oriented in the vertical plane (lifting assembly). One end of a bar ( the load cell lifting lever) is pivotally attached to the end of the hydraulic cylinder, while the other end of the bar is pivotally attached to a rigid structure, the top plate pin support. Between the hydraulic cylinder and the top plate pin support is a double ended shear beam load cell, which is a narrow, relatively deep object with an upper and a lower opening through it. The load cell is held in place solely by the bars which pass through these openings. The load cell lifting lever passes through the upper opening in the load cell. The top plate of the module is configured so that the entire weight of the plate and any load on it is concentrated in the lower lift pin, whose end passes through the lower opening of the load cell. When the hydraulic cylinder is extended, the load cell lifting lever pivots about its attachment to the top plate pin support and exerts an upward force on the inside face of the upper opening of the load cell. This force moves the load cell in an upward direction which causes it to exert an upward force against the lower lift pin which in turn lifts the load. Specially machined surfaces on the inner face of the upper opening and on the load cell lifting lever allow the cell to position itself along the lever and to hang vertically while being lifted. When all four weigh cells are activated at the same time, the entire load is supported by the four weigh cells. Their combined out put indicates the weight of the load.
[9] Prairie denies that its device infringes the patent though some of the particulars of its denial are directed to the description of the embodiment contained in the patent specification or to the device manufactured by the plaintiff. It is settled law that it is the claims which define the monopoly accorded by the patent, so that infringement is defined by reference to the claims, and not to the specification or the preferred embodiment. The eminent author Fox put the matter thus:
Infringement must be based upon the invention as claimed and not upon the invention as described in the evidence or as constructed by the plaintiff. It is quite irrelevant to compare a defendant's structure with that of the plaintiff who claims to be manufacturing under his patent. What must be compared are the defendant's structure and that defined in the claims for it is obvious that the plaintiff's structure may itself not be within the claims of his patent.
Fox, Harold G., The Canadian Law and Practice relating to Letters Patent for Inventions, 4th ed. (Toronto: Carswell 1969) at p. 355.
[10] The defendant's case was conducted on the basis that a finding of infringement could be avoided if the defendant could be shown to be using a different combination and arrangement of parts than did the Plaintiff. While the plaintiff's case is that the defendant's device infringes the patent on a literal reading of the latter, it says in response to the defendant that even if certain substitutions are found to have been made, the patent is substantially infringed.
[11] The doctrine of substantial infringement was recently considered in the case of Free World Trust v. Électro Santé Inc. [2000] 2 S.C.R. 1024 where Binnie J. reviewed the issue of literal and substantial infringement of a patent. He concluded that the doctrine of substantial infringement could not be used to avoid the consequences of the language used in the patent by the inventor:
It is obviously an important public policy to control the scope of "substantive infringement". A purely literal application of the text of the claims would allow a person skilled in the art to make minor and inconsequential variations in the device and thereby to appropriate the substance of the invention with a copycat device while staying just outside the monopoly. A broader interpretation, on the other hand, risks conferring on the patentee the benefit of inventions that he had not in fact made but which could be deemed with hindsight to be "equivalent" to what in fact was invented. This would be unfair to the public and unfair to competitors. It is important that the patent system be fair as well as predictable in its operation. (emphasis added)
Free World Trust, supra, para 29
It would be unfair to allow a patent monopoly to be breached with impunity by a copycat device that simply switched bells and whistles, to escape the literal claims of the patent. Thus the elements of the invention are identified as either essential elements (where substitution of another element or omission takes the device outside the monopoly), or non-essential elements (where substitution or omission is not necessarily fatal to an allegation of infringement). For an element to be considered non-essential and thus substitutable, it must be shown either (i) that on a purposive construction of the words of the claim it was clearly not intended to be essential, or (ii) that at the date of publication of the patent, the skilled addressees would have appreciated that a particular element could be substituted without affecting the working of the invention, i.e., had the skilled worker at that time been told of both the element specified in the claim and the variant and "asked whether the variant would obviously work in the same way", the answer would be yes: Improver Corp. v. Remington, supra, at 192. In this context, I think "work in the same way" should be taken for our purposes as meaning that the variant (or component) would perform substantially the same function in substantially the same way to obtain substantially the same result. ...
Free World Trust, supra, para 55
[12] It can be seen from these passages that the question of substantial infringement is now a question of essential and non-essential elements of the claims. If the substituted elements are not essential, then their replacement by an equivalent combination of parts is a matter of no consequence; infringement can still be found. However, in the case of essential elements, their absence or their substitution will lead to a finding of no infringement. So while there is still scope to inquire as to whether what has been done by the defendant is simply a replacement of one element by an equivalent assembly, that conclusion, by itself, is not determinative of infringement.
[13] There is a further consideration in construing the claims of the patent, particularly where the invention consists in novel combination of known parts to achieve a particular result.
As stated, the ingenuity of the patent lies not in the identification of a desirable result but in teaching one particular means to achieve it. The claims cannot be stretched to allow the patentee to monopolize anything that achieves the desirable result. It is not legitimate, for example, to obtain a patent for a particular method that grows hair on bald men and thereafter claim that anything that grows hair on bald men infringes.
Free World Trust, supra, para 32
[14] In reasons released concurrently with those in Free World Trust, supra, the Supreme Court dealt with the construction of claims in Whirlpool Corp. v. Camco Inc. [2000] 2 S.C.R. 1067. Binnie J., speaking for the court once again, held that the first task of a judge dealing with a patent claim was to construe the patent. This is to be done by applying the principles of purposive construction, a process described as follows:
The key to purposive construction is therefore the identification by the court, with the assistance of the skilled reader, of the particular words or phrases in the claims that describe what the inventor considered to be the "essential" elements of his invention.
Whirlpool Corp., supra, para 45
[15] It is to be noted that the Court found that purposive construction could narrow as well as expand the scope of the protection afforded by the patent.
However, purposive construction is usually criticized by accused infringers for tending to expand the written claims. In fact, purposive construction can cut either way. ... Purposive construction is capable of expanding or limiting a literal text, as Hayhurst, supra, points out at p. 194 in words that anticipate the trial judgment in this case:
Purposive construction may show that something that might literally be within the scope of the claim was not intended to be covered, so that there can be no infringement...
Similarly, two other experienced practitioners, Carol V. E. Hitchman and Donald H. MacOdrum have concluded that "[a] purposive construction is not necessarily a broader construction than a purely literal one, although it may be" (Hitchman and MacOdrum, "Don't Fence Me In: Infringement in Substance in Patent Actions" (1990), 7 C.I.P.R. 167, at p. 202).
Whirlpool. Corp., supra, para 49
[16] A purposive construction must amount to more than a summary of the main elements of a device (in the case of a mechanical patent). Since a patent, by definition, concerns a novel and useful device, a purposive construction of a patent must identify the functional elements which make the device novel and inventive. Since it is the means by which a result is obtained which is protected by the patent, rather than the result itself, a purposive construction of a patent should identify those functional elements which produce a useful result in a novel and inventive way. To that extent, it is not useful to say that all elements of a claim are equally essential in that the invention cannot function in the absence of any one of them. The inquiry ought to focus on identifying the elements whose absence will result in the device ceasing to be inventive.
[17] With that in mind, one turns to a construction of claims 6 and 7. Claim 6 is reproduced below for ease of reference:
A weighing cell for use in a mobile weighing system, comprising a lifting mechanism having an extended and a rest position, a vertically disposed tension load cell which produces an output correlated to a tension load thereon and a linkage assembly whereby said linkage assembly couples said lifting mechanism and said load cell to cause an upward force on a first end of said load cell when said lifting mechanism is in an extended position, the second end of said load cell being configured for coupling to a load support frame such that said load support frame may be suspended by a plurality of said load cells when the lifting mechanisms thereof are in extended positions.
[18] Claim 6 describes an arrangement by which a load located above a weighing device may be lifted and weighed. The load is attached to a load support frame which is more adapted for lifting than the load itself by reason of its location and configuration. A lifting mechanism is configured so that its lifting force acts through a tension load cell to lift the load support frame, as a result of which the tension forces acting on the load cell produce an output which can be used to determine the weight carried by the load cell. The load cell must remain vertically disposed to avoid the error induced by measuring off-axis. The essential elements of claim 6 are a load support frame, a lifting mechanism, and a linkage system whereby the lifting force of the lifting mechanism is applied to a tension load cell which, while remaining vertically disposed, lifts and suspends the load support frame, and produces an output correlated to the tension load by which the weight of the load may be determined.
[19] Claim 7 describes the linkage system by which the lifting force of the lifting mechanism is transferred to the tension load cell in such a way as to lift the load support frame while becoming or remaining vertically disposed.
A weighing cell according to claim 6 wherein said linkage assembly comprises a stationary bar and a cross-arm pivotally attached thereto and said first end of said load cell is pivotally attached to said cross-arm whereby said load cell remains vertically disposed when said lifting mechanism is in an extended position.
[20] Claim 7 describes a lever whose fulcrum is a pivotal attachment to a stationary object, and to which force is applied by the lifting mechanism. The force generated by the lifting mechanism is transferred to the tension load cell by means of a pivotal attachment of the tension load cell to the lever such that the upward movement of the lever applies an upward force to the tension load cell while allowing it to remain vertically disposed. The essential elements of claim 7 are the pivotal attachment of the tension load cell to the lever by which the upward force of the lifting mechanism is transferred to the tension load cell and to the load, which is free to find the vertical axis..
[21] Having thus construed the patent, the first issue to be dealt with is invalidity. The defendant raises three issues in respect to invalidity. The first is that the claims are ambiguous. Then, it argues that the invention cannot function as described in the patent. Finally, it says that the invention was obvious and was anticipated by other patents, in particular European Union patent No. EP476778B1 issued to Nuyts on Dec. 13, 1995.
[22] I find no merit in the allegation that the claims are ambiguous. The plaintiff alleges that in claim 6 the linkage assembly consists of the load cell rod ends and in claim seven it consists of a stationary bar and cross arm. If one looks to the relevant portions of claim 6 the following emerges:
" ... and a linkage assembly whereby said linkage assembly couples said lifting mechanism and said load cell ..."
[23] Claim 7 provides that:
" ...said linkage assembly comprises a stationary bar and a cross-arm pivotally attached thereto ..."
[24] Claim 6 describes the function of the linkage assembly and claim 7 describes the components of the linkage assembly. There is no ambiguity or confusion.
[25] The next issue in relation to validity is the allegation that the invention as described in the patent does not work. This arises because of the lateral movement of the point of attachment of the tension load cell as the cross-arm is being raised. In his cross-examination, Professor Schoenau, the plaintiff's expert witness, admitted that the end of cross-arm moves in an arc as it is being raised as does the point of attachment of the load cell to the cross arm. This results in the point of attachment moving closer to the stationary bar as it is raised. As the tension load cell follows its point of attachment, it applies lateral forces to the load support frame. These forces are opposed by the forces applied by the weigh cell opposite the first, and by the rigidity of the load support frame itself both of which would force the load cell off the vertical axis and introduce error into the measurement.
[26] Mr. Smith, the defendant's expert witness, described the lateral movement of the point of attachment as arising from the fact that as the cross arm pivots, the vertical distance between the point of attachment and the pivot pin at the cross arm and stationary bar changes, forcing the load frame to move sideways. This is the same phenomenon described by Professor Schoenau but set out in different terms.
[27] In his re-examination Professor Schoenau indicated that it was only necessary to lift the load enough to clear the truck deck in order to weight the load. He thought that this degree of lift would result in very little lateral displacement which would not interfere with the operation of the device. He also noted that drawing no. 2 of the patent showed the cross-arm at rest being positioned at an angle less than horizontal. He was led to say that if the arm was raised to an angle above horizontal equal to the angle at rest, the point of attachment would be in the same axis at both locations, meaning that there was no horizontal displacement relative to the starting point. Objection was properly taken to this evidence but in the end it does not assist the plaintiff. Mr. Smith made the point in his evidence that the degree of lift is dictated by the amount of extension of the hydraulic ram not by the minimum amount of lift required to achieve suspension. His evidence is that upon being actuated, the hydraulic ram will fully extend and the amount of that extension determines the amount of lift. Consequently, the fact that the device could function with less lift is no answer. The argument based on the rest angle of the cross-arm is subject to the same consideration.
[28] Professor Schoenau also admitted that unless the hydraulic cylinder is pivotally attached to the truck or trailer bed, the arc movement of the cross arm imposes lateral forces on the hydraulic ram which will eventually bend it. As the ram extends upward, the movement of the cross arm in an arc would pulls the end of the ram out of the plane in which it is extending and will eventually bend it. The claims and specification are silent on the subject of the pivotal attachment of the lifting mechanism to the underlying deck. In fact the specification appears to contemplate a rigid attachment of the lifting mechanism
Both the stationary bar 105 of the linkage assembly and the lifting mechanism 80 are secured to the deck frame 50 (and therefore the truck frame 60) by means of transverse reinforcing bars 110 to which they are attached using appropriate hardware.
[29] Professor Schoenau stopped short of saying the invention would not work in the absence of these measures, but it is the only conclusion which can be drawn from his evidence. The evidence is persuasive that the invention described in the patent does not deal with lateral forces acting on the tension load cell. According to the theory underlying the invention, this introduces error into the measured weight.
[30] Even if it were found that the device would work as claimed if operating limitations are imposed[1], the fact is that they appear nowhere in the claims or the specification. It is a principle of some antiquity that the manner of operation of a machine must be disclosed as well as its design so that upon the expiry of the monopoly period, one skilled in the art could not only design and construct such a machine but operate it as well. The principle is stated in Noranda Mines Ltd. v. Minerals Separation North American Corp., [1947] Ex. C.R. 306 at pp. 316-17 as follows:
Two things must be described in the disclosures of a specification, one being the invention, and the other the operation or use of the invention as contemplated by the inventor, and with respect to each the description must be correct and full.
...
The description must also give all information that is necessary for successful operation or use of the invention, without leaving such result to the chance of successful experiment, and if warnings are required in order to avert failure such warnings must be given.
[31] Consequently, if the limitations suggested by the plaintiff have the effect which was claimed for them, their absence from the patent is fatal. If they do not have the effect which is claimed for them, then the device discribed in the claims cannot work in any event.
[32] A device which does not work lacks utility, a quality which must be present in order for a patent to issue. Subsection 27(1) of the Patent Act, R.S.C. 1985, c. P-4, provides for the issue of a patent in respect of an invention. The definition of invention is "... any new and useful art, process, machine, manufacture or composition of matter, or any new and useful improvement in any art, process, machine, manufacture or composition of matter"[2]. The weigh cell, as claimed in claims 6 and 7, lacks utility and so the claims are invalid.
[33] The defendant also alleges invalidity on the ground of obviousness and anticipation. Mr. Strelioff testified that none of the elements used in the invention are novel, nor is the use to which they are put in the invention novel. It is not novel, for example, to use a lever and a hydraulic cylinder to lift a load. Mr. Strelioff's view was that the novelty consisted in the arrangment of known elements to achieve a useful result, specifically a means of weighing a load in non-level conditions. Professor Schoenau testified that while all of the elements of the invention were well known, suspension of a load located above the weigh cell was unique and inventive. Professor Shoenau's view was that the simplicity of the invention was a unique feature but conceded that that simplicity came at the price of not dealing with the problem of lateral loading.
[34] Professor Schoenau also offered the opinion that none of the patents cited at various times as prior art anticipated the invention. According to him, they all dealt with the use of load cells to measure compression forces, whereas the invention uses a tension load cell to weigh a load. In Professor Schoenau's opinion, the invention "represents a departure from the weighing system designs of the patents referenced by the Defendant".
[35] In his written report Mr. Smith referred to a number of patents which he said anticipated the invention. However of those, only the Harvill patent and the first Nuyts patent EP476778B1 preceded the invention so as to be capable of being prior art. Mr. Smith's report claims that the the Harvill patent "utilizes a lifting mechanism to suspend the tank from load cells." In cross examination, he conceded that the Havrill patent measured compression and not tension to arrive at the weight of the load. The Nuyts patent teaches the use of universal joints, a form of flexible connectors, to weigh a load. In Mr. Smith's view, the combination lifting and locking mechanism in the patent in suit is new and "exhibits some degree of ingenuity".
[36] Professor Schoenau commented upon the Nuyts patent in rebuttal and noted that the object of the invention is "to minimize the distance that is required between a loading frame and the surrounding structure to which it is attached by connecting elements." He discussed the patent and concluded that it teaches away from the structure of the weighing cell defined in the patent in suit:
As seen in Figure 2 of the load cell of the subject patent, which is attached and marked as Exhibit B to this my Affidavit, the load cell (90) load support (20) and connecting linkage (100) are located in the space between the lifting mechanism (80) and stationary bar (105). If one follows the teachings of the Nuyts reference, the arrangement would be subject to too much horizontal movement between load support (20) and its supporting frame (consisting in part of the lifting mechanism (80) and stationary bar (105) so as to render the weighing system inaccurate at very small oblique angles. This is clearly not the case, and the device disclosed in the subject patent can accurately weigh loads at angels (sic) commonly encountered in practice.
[37] The plaintiff also relies upon the Notice of Allowability issued by the United States Patent Office when issuing a patent. When a United States patent was applied for in relation to the invention, the United States Patent Office issued a Notice of Allowance saying:
The cited prior art does not disclose a tension load cell that is raised by an extended lifting mechanism to operate a linkage that raises the upper end of the tension load cell to a point to support an applied load on the lower end of the tension load cell.
[38] It is difficult to know what this means, given the reference to "the cited prior art". The conclusion is a function of what was cited. The Notice of References Cited refers to three documents but those documents are not before the court. Consequently, no conclusion can be drawn from this exhibit.
[39] No evidence was led as to the state of knowledge of a person skilled in the art at the relevant date from which one could come to any conclusion as to obviousness. The test of obviousness was set out by Huguessen J.A. in Beloit Canada Ltd.et al. v. Valmet Oy (1986) 8 C.P.R. (3d) 289 (F.C.A.) at 294:
The test for obviousness is not to ask what competent inventors did or would have done to solve the problem. Inventors are by definition inventive. The classical touchstone for obviousness is the technician skilled in the art but having no scintilla of inventiveness or imagination; a paragon of deduction and dexterity, wholly devoid of intuition; a triumph of the left hemisphere over the right. The question to be asked is whether this mythical creature (the man in the Clapham omnibus of patent law) would, in the light of the state of the art and of common general knowledge as at the claimed date of invention, have come directly and without difficulty to the solution taught by the patent. It is a very difficult test to satisfy.
[40] I find that the invention was not anticipated by the patents which precede the "laid open" date and which were cited as prior art. Free World Trust v. Électro Santé Inc., supra, at para 54. On the question of obviousness, there is no evidence before me on which I could find that a person skilled in the art, employing the common general knowledge of such persons, could have come to the invention without employing imagination or intuition. Confronted with the presumption of validity, and the absence of evidence to the contrary, there is no basis on which I can conclude that the patent is invalid for obviousness.
[41] To recapitulate, I have concluded that the invention described in the patent lacks utility because if constructed in accordance with the patent, it will not work, or will only work under certain operating conditions which are not described in the patent. To that extent the patent is invalid for lack of utility. However, if I am wrong about that, I find that the patent is not invalid for anticipation or obviousness.
[42] The next issue is infringement. The plaintiff alleges that claims 6 and 7 can be read upon the defendant's device to show a clear infringement of both claims. This can perhaps be best illustrated by parsing the claims and interspersing the plaintiff's views as to the corresponding elements of the defendant's device
A weighing cell for use in a mobile weighing system, comprising a lifting mechanism having an extended and a rest position
The defendant's device has a hydraulic cylinder with has an extended and a rest position.
a vertically disposed tension load cell which produces an output correlated to a tension load thereon
The defendant's load cell is configured so that the tension forces created by the extension of the hydraulic cylinder act upon the load cell in a vertical alignment. The lift force is applied at the upper opening by the load cell lifting lever and the weight is applied below it in the lower opening by the lower lift pin. The load cell is therefore vertically disposed and produces an output which is correlated to the tension forces applied to it. Because the load cell function under tension forces, it is a tension load cell.
and a linkage assembly whereby said linkage assembly couples said lifting mechanism and said load cell to cause an upward force on a first end of said load cell when said lifting mechanism is in an extended position
The linkage assembly in the defendant's device consists of the load cell lifting lever which is attached to the hydraulic cylinder and which is coupled to the load cell in that upward movement of the lever as a result of the extension of the hydraulic cylinder results in upward movement of the load cell.
the second end of said load cell being configured for coupling to a load support frame such that said load support frame may be suspended by a plurality of said load cells when the lifting mechanisms thereof are in extended positions.
The second end of the load cell is the lower opening in the load cell which is made to receive the lower lift pin. The lower lift pin is an integral part of the top support plate assembly in that the entire assembly can be lifted by applying force to the lower lift pin. When all four cylinders in the two modules which are required to constitute the defendant's weighing system are activated, the entire load is suspended by the load cell.
[43] Counsel for the defendant applied himself to the task of demonstrating that the defendant's device did not contain any of the constituent elements of the invention. He put into the question whether the defendant's device had a load support frame, a double acting hydraulic cylinder, rod ends, a vertically disposed tension load cell, a linkage system. Some of these elements are not referred to in the claims and their absence would not support a finding of no infringement. For example, claim 6 requires a lifting mechanism with a rest and an extended position. It does not require a double acting hydraulic cylinder. Similarly, neither claim 6 nor 7 refer to rod ends. Mr. Smith's evidence that the top support plate of the defendant's device is not a load support frame because is not constructed of 4 by 6 inch steel tubing as set out in the specification. There is no such requirement in claims 6 or 7. All that to say that infringement cannot be avoided by showing a deviation from the preferred embodiment set out in the specification.
[44] The are two questions which do arise from the claims however, and they are the presence (or absence) of a vertically disposed tension load cell which produces an output proportional to the tension forces applied and a tension load cell which is either coupled to or pivotally attached to a cross arm. The task is to determine if these are present in the defendant's device and whether their absence (if that is the case) results in a finding of non-infringement according to the construction of the claims set out earlier in these reasons.
[45] The defendants strenuously deny that their device employs a tension load cell or that the output of their cell correlates to the tension load applied to the cell. The evidence of Mr. Strelioff was that tension load cells come in many sizes and shapes depending upon the application in which they are to be used. Their common feature, when used in a vertical disposition, is that they measure the tension forces between an upper and a lower point. The question of the precise means by which the tension forces are measured is a secondary consideration. If the device functions when subject to tension forces and the output varies with those tension forces, it is effectively a tension load cell.
[46] Professor Schoenau testified that "tension load cell" refers to a class of devices which measures the amount of pulling force applied at each end of the device. This implies that the device is in-line, that is, the cell is the link between a force and an opposing load or force.
[47] Mr. Elliott described Exhibit 8, the load cell in the defendant's device, as a double ended shear beam load cell with a linkage system. He described how a shear beam load cell works by applying a load to the end of a horizontally supported beam which results in a shear force which is measured by the strain gauges in the cell. In order for a shear beam load cell to function, the loads must be applied to the end of the beam while the beam is supported from the centre. A double ended shear beam is one in which the force to be measured can be applied to either or both ends of the beam. When designing a load cell for the its device, the defendant required a device with a low profile since its primary market is retrofitting existing delivery platforms.
[48] The design choice which it made was to weld to the bottom of it double ended shear beam load cell a linkage system which would take loads applied below the shear beam and transfer them to the ends of the shear beam inducing shear forces which the strain gauges would then measure. The linkage assembly is the triangular bottom portion of Exhibit 8 which has within it the two openings through which pass the load cell lifting lever and the lower lift pin. By welding this to the shear beam load cell, the weight of the load which is brought to bear on this linkage system is transferred to the ends of the double ended shear beam load cell. Mr. Elliott's position is that the shear beam portion of the combined assembly is never under tension, because the force is applied at the end of the load cell.
[49] Mr. Elliott's evidence was that the same result could have been achieved by using a bolted connection of some description to transfer the load to the top of the shear beam load cell but that this was impractical given the low profile which the defendants were seeking for their device.
[50] Mr. Elliott was confronted with Exhibit 25 which is a brochure produced by The defendant describing its double ended shear beam product. The pamphlet describes the device as being suited for "high tension applications". Mr. Elliott was forced to concede that the device is used in tension applications.
[51] The plaintiff's position as set out in the evidence of Mr. Strelioff and Professor Schoenau is that the device as a whole is in tension as a result of the lift force applied to the upper opening and the opposing weight of the load which is applied at the lower opening. According to professor Schoenau, the fact of the cell being in tension could be demonstrated by notionally cutting the cell between the upper and lower openings and observing what would happen to the two parts. They would be pulled apart, which indicates an element in tension. Since this tension results in an output which is used to measure weight, it follows that the output is proportional to the tension forces applied. This