Supreme Court Decision
On
Doctrine of Equivalents

Translated by
Chris T. Mizumoto and Yusuke Hiraki
Hiraki & Associates(Tokyo)

PATENTS & LICENSING, April, 1998


February 24, 1998/Case No. 1994 (o) 1083
Appellant: Tsubakimoto Seiko Co., Ltd
Appellee: THK K.K.

An appeal was filed by the appellant against the Decision (Tokyo High Court Patent Infringement - Injunction case No.1991 (Ne) 1627) handed down on February 1994 by the Tokyo High Court. The present Court decides as follows:

Main Statements

The Original Decision is reversed.

The present case is remanded to the Tokyo High Court

Reason

With respect to the grounds for appeal filed by the appellant's attorney Yohei Kinoshita:

1. The present case is a suit demanding payment of damages by the appellee on the grounds that the appellant infringed the patent right of the appellee. Summary of the facts of the original appeal is as follows:

(1) The appellee owns a patent right to an invention entitled "Endlessly Sliding Ball Spline Shaft Bearing" (Application date: April 26, 1971; Publication date: July 7, 1978; and Registration date: May 30, 1980; Patent No.999139)(this patent right hereinafter will be referred to as the present patent right, and the invention thereof will be referred to as the present invention).

(2) The details of the claim set forth in the specification of patent application of the present invention (hereinafter referred to as the present specification) are as follows.

"An endlessly sliding ball spline shaft bearing (hereinafter referred to as constituent feature E), which comprises:

An outer cylinder having torque transmitting load bearing ball-guiding grooves with a U-shaped cross-section and torque transmitting non-load bearing ball-guiding with the U-shaped cross-section being slightly deeper than that of the load bearing ball-guiding grooves, the load bearing ball-guiding groove and the non-load bearing, ball-guiding groove extending alternately in the axial direction within the cylindrical inner wall, the outer cylinder having an annular circumferentially directed groove at each end with the same depth as that of the deeper groove (hereinafter referred to as constituent feature A);

A thin wall portion and the tick wall portion formed respectively in conformity with the torque transmitting load bearing ball-guiding groove and the torque transmitting non-load bearing ball-guiding groove formed in the axial direction within the inner wall of the outer cylinder;

A joint portion between the thin wall portion and the thick wall portion having a through-hole;

A retainer with an endless track groove for allowing balls to smoothly slide into the non-load ball-guiding groove formed in the thick wall portion (hereinafter referred to as constituent feature B); and a spline shaft provided with a plurality of ribs extending in the axial direction thereof, said ribs being shaped to conform with a plurality of recessed spaces formed by the balls incorporated between the retainer and said outer cylinder (hereinafter referred to as constituent feature C) for engaging the spline shaft with the outer cylinder (hereinafter referred to as constituent feature D).

(3) During the period of January 1983 to October 1988, the appellant had manufactured and sold a product described in the inventory attached as an annex of the original Decision. (This product is however provided with a step of about 50 microns in height between the non-load ball-guiding groove 5 and the cylindrical portion 7 (circumferentially directed portion 7). (This product will be hereinafter referred to as appellant's product.)

2. The appellee asserted that the features of the appellant's product encompass or equivalent to all of the constituent features of the present invention, and therefore, the appellant's' product falls within the technical scope of the present invention. After considering the apellee's assertion, the judges in the original appeal acknowledged the appellee's demand for payment of damages for infringing the present patent right as follows:

(1) The appellant's product encompasses constituent features C, D and E.

(2) With respect to constituent feature A, according to the present invention, there are elements such as "U-shaped cross-section" and "annular circumferentially directed grooves". Whereas, according to the appellant's product, the corresponding portions of these elements are "semi-circular cross-section" and "cylinder portion 7", and hence, these differ from the constituent feature of the present invention.

(3) With respect to constituent feature B, the retainer of the present invention is an integral structure providing the functions of guiding balls to move in endless circulation, retaining balls when the spline shaft is withdrawn, and forming a recessed portions for guiding the rib portion of the spline shaft. Whereas, according to the appellant's product, these function of the present invention are effected by the cooperative action of three members, i.e. the upper edge portions of the ribs formed between the load bearing ball-guiding grooves of outer cylinder, a plate-like member 11 and return cap 31, and hence, these differ from the constituent feature of the present invention.

(4) However, the appellant's product is substantially the same as that of the present invention with respect to the solution for solving the technical problem, the basic technical idea, and the effects obtained by these constituent features. Namely, with regard to the structure of the retainer constituting constituent feature B, there is recognized interchangeability between the present invention and the appellant's product and ease of interchangeability at the time of filing. Further, no special technical significance can be attributed in the appellant's product in terms of differences between the "U-shaped cross-section" and "annular circumferentially directed grooves" constituting constituent feature A and the "semi-circular cross-section" and "cylindrical portion 7" of the appellant's product. Accordingly, it is deemed reasonable to recognize that the appellant's product falls within the technical scope of the present invention.

3. However, the above Decision of the original appeal cannot be averred for the reasons as follows:

(1) In determining whether or not the product made by the other party or the method employed by the other party (hereinafter referred to as "corresponding product etc.") falls within the technical scope of a patented invention in a patent right infringement appeal, the technical scope of the patented invention must be determined based on the description of claims in the specification attached to the application (see Patent Law Section 70 (1)). If there are elements that differ between the constitution described in a patented claim and corresponding product and the like, the corresponding product and the like cannot be said to fall within the technical scope of the patented invention. On the other hand, even if there are elements in the constitution described in a patented claim that differ from the corresponding product and the like, the corresponding product and the like may be equivalent to the constitution described in claim and may appropriately be said to fall within the technical scope of the patented invention if the following conditions are satisfied: (1) the differing elements are not the essential elements in the patented invention; (2) even if the differing elements are interchanged by elements of the corresponding product and the like, the object of the patented invention can be achieved and the same effects can be obtained; (3) by interchanging as above, a person of ordinary skill in the art to which the invention pertains (hereinafter referred to as an artisan) could have easily achieved the corresponding product and the like at the time of manufacture etc. of corresponding product; (4) the corresponding product and the like are not the same as the known art at the time of application for patent or could not have been easily conceived by an artisan at the time of application for patent; and (5) there is not any special circumstances such that the corresponding product and the like are intentionally excluded from the scope of the claim during patent prosecution.

It would be very difficult to write down claims at the finding in anticipation of all type of future infringing situations. Additionally, if enforcement of patent right such as injunction and such by a patentee can be easily circumvented by another party by interchanging a material or a technique-a portion of the constituent features of the claim that is made clear after the filing of the patent application, the drive for invention by the public would be diminished. This not only violates the purpose of patent law to contribute to the development of industries through protection of and encouragement for invention, but also denies social justice, resulting in the breach of the concept of equity. (2) In view of these circumstances, it should be understood that the substantive value of a patented invention should be extended from the claims to cover a technology easily obtainable by a third party, which is substantially identical with the constitution described in the claims, and that this could be anticipated by a third party. (3) On the other hand, since it is not expected for anyone to obtain a patent based on a technology known publicly or easily conceived by an artisan at the time of the filing the patent application (see Patent Law Section 29), such a technology can never be included in the technical scope of a patented claim. (4) once a patentee excludes a technology from the technical scope of a patented invention by intentionally excluding it from the scope of the claim during patent prosecution or committing an act that can be outwardly interpreted as doing so, the patentee cannot substantially make assertions that would contradict this exclusion since such a contradiction would not be permitted in view of the law of prosecution estoppel.

(2) Applying this to the present case, although some differences between the claim of the present specification and the appellant's product were found with respect to constituent features A and B in the original appeal, the appellant's product was determined in the original appeal to fall within the technical scope of the present invention for the reasons that there was interchangeability as well as ease of interchangeability between the present invention and the appellant's product with regard to constituent feature B and the like.

However, it is acknowledged in the original appeal that (I) an endlessly sliding ball spline shaft bearing, constituted by an outer cylinder, a spline shaft and a retainer, was already known prior to the application of the present invention; further, a spline shaft provided with a plurality of ribs extending in the axial direction thereof, the ribs being shaped to conform with a plurality of recessed spaces formed by the balls incorporated between the retainer and the outer cylinder (constituent feature C), is an ordinary shaft that has been commonly employed for a ball spline bearing: and that (II) (1) the retainer according to the present invention is an integral structure providing the functions of guiding balls to move in endless circulation, retaining balls when the spline shaft is withdrawn, and forming recessed portions for guiding the rib portions of the spline shaft; the retainer according to the appellant's product is a split type structure consisting of three plate-like members 11, a couple of return caps 31 and the ribs 25, 27 and 29 formed between the load bearing ball-guiding grooves of the outer cylinder; and the aforementioned functions of the present invention are effected in the appellant's product by the cooperative action of these members; (2) the retainer of the split type structure consisting of three plate-like members 11 and a couple of return caps 31 according to the appellant's product has already been shown in an endlessly sliding ball spline shaft bearing described in U.S. patent No. 3,360,308, published before the application date of the present invention; and (3) the ribs between the load-bearing ball-guiding grooves of the outer cylinder as being technically necessary in order to retain balls by means of such a slit-type retainer is apparent from a ball spline described in US patent No. 3,398,999, published before the application date of the present invention.

According to the aforementioned Decision in the original appeal, a retainer of the split type structure as well as ribs between the load-bearing ball-guiding grooves of the outer cylinder in the appellant's product were already shown in the known ball spline bearing disclosed prior to the application date of the present invention.

Further, according to the aforementioned to the Decision in the original appeal, the appellant's product is similar to the present invention in that the non-load bearing balls are adapted to circulate in the circumferential direction and that a plural-array type angular contact structure in which both sides of the rib portion of the spline shaft are held between a pair of load bearing balls fitted in the torque-transmitting load-bearing ball-guiding grooves, is utilized, (Constituent features A and C). However, since it was acknowledged in the original appeal that both the circulation of the non-load bearing ball in the circumferential direction and the plural-array type angular contact structure were already described in Japanese Patent Publication S/44-2361, in German Federal Republic Patent No. 1,450,060 and in U.S. Patent No. 3,494,148, all published prior to the application date of the present invention, it is deemed that uses of these technologies for a ball spline bearing have been publicly known prior to the application date of the present invention.

Therefore, given that the technologies related to the ball spline bearing provided with the circulation of the non-load bearing ball in the circumferential direction and with the plural-array type angular contact structure, were publicly known prior to the application date of the present invention, the appellant's product is deemed to be simply a combination of a ball spline bearing, which is provided with the known circulation of the non-load bearing ball in the circumferential direction and with the known plural-array type angular contact structure, and a known split type retainer, because it is acknowledged in the original appeal that basically the structure of the retainer cannot be distinguished by the contacting structure of the balls. Given that this combination could have been easily arrived at by an artisan without the disclosure of the present invention, it is deemed that the artisan could have easily conceived the appellant's product at the time of the application date of the present invention from the known art published before the application date of the present invention. Therefore, the appellant's product cannot be said to be equivalent to the constitution set forth in the claim of the present specification, and the appellant's product cannot be said to fall within the technical scope of the present invention.

As described above, it was acknowledged in the original appeal that some of the constituent features set forth in the claim of the present specification differed from those of the appellant's product. However, only the topic of whether or not there exist any interchangeability or ease of interchangeability between the differing elements of the present invention and the constitution of the appellant's product was examined in the original appeal. Then, without discussing the relationship between the appellant's product and the known art at the time of the application of the present invention, a decision was summarily made in the original appeal to the effect that the appellant's product was equivalent to the constitution set forth in the claim of the present specification, and that the appellant's product fell within the technical scope of the present invention.

Therefore, it cannot but be said that the aforementioned Decision made in the original appeal is erroneous in interpretation and application of the Patent Law, thus making it unnecessary to discuss the propriety of the decisions made in the original appeal on other requirements such as equivalence, e.g. interchangeability or ease of interchangeability.

4. As explained above, The Decision of the original appeal is erroneous in interpretation and application of Patent Law. In other words, it is unlawful in terms of premature decision and deficient reasoning. It is apparent that this unlawful interpretation and application has affected the conclusion of the original Decision.

There is a reason for the points of argument as explained above, and original Decision cannot but reversed. Further, since the aforementioned points should be fully reconsidered in the original appeal, this case is thus remanded.