英文文献：Patent Breadth As An Entry Deterrent: The Case Of Vertically Differentiated Product Innovations-专利宽度作为进入的阻碍:垂直差异化产品创新的案例
英文文献作者：Yiannaka, Amalia,Fulton, Murray E.
英文文献摘要：
Patents provide very important incentives for innovative activity by enabling innovators to appropriate innovation rents through the granting of exclusive rights on their innovations. The limit of these exclusive rights is defined by two elements - patent length and patent breadth. Patent length is the time period during which the innovator has exclusive rights on the innovation and is predetermined by law. Patent breadth defines the technological territory claimed and protected by the patent - the area in the technological space within which competitors cannot offer rival innovations without infringing the patent - and is explicitly chosen by the innovator. A standard assumption in the economics literature is that an innovator should always choose to claim the maximum patent breadth, thereby deterring the entry of other firms and thus enabling the innovator to earn monopoly rents (see Gilbert and Shapiro and Gallini for examples of this view). Such a strategy, however, fails to recognize that patents are often challenged legally in the Patent Office or in the courts (Cornish). The nature of this challenge is such that the broader is the patent protection, the higher is the probability that the patent will be challenged legally by competitors, that it will overlap another patent and/or that the courts will invalidate it or narrow its scope (Lerner). Given that patent breadth is routinely challenged, the question arises as to whether the innovator is able to choose a patent breadth that deters entry, or whether the innovator is forced to share the market with a new entrant. The purpose of this paper is to examine the optimal patent breadth strategy that an innovator should employ when faced with the possibility that the patent breadth claimed will be challenged. In this paper, the optimal patent strategy is determined in a sequential game of complete information. The agents in the game are an innovator who seeks patent protection and decides on the patent breadth claimed and a potential entrant who decides on whether to enter the patentee's market and, if entry occurs, where to locate in the vertically differentiated product space. The solution to this game is obtained by backward induction - the problem of the entrant is examined first, followed by the problem of the innovator. The paper shows that that it is possible under some conditions for an innovator to use patent breadth to deter entry - when this is possible, the optimal patent strategy is to always deter entry. These conditions occur under certain combinations of the entrant's R&D effectiveness and trial cost values (i.e., low R&D effectiveness - which results in high R&D costs - and high trial costs). When these specific conditions do not hold, the optimal strategy for the innovator is to allow a new competitor to enter the market. When allowing entry, the innovator chooses patent breadth so that the benefits of increased product differentiation that result from greater patent breadth are traded off with the increased likelihood of patent challenge that comes with greater patent breadth. One of the conclusions of the paper is that the innovator will only choose the maximum patent breadth when patent infringement is never an optimal strategy for the entrant. This occurs under a very specific set of conditions (i.e., a combination of very high R&D effectiveness and high trial costs values).

专利为创新活动提供了非常重要的激励，通过授予创新者对其创新的专有权，使其能够获得适当的创新租金。这些专有权的限制由专利长度和专利宽度两个要素来界定。专利期限是指由法律规定的创新者对其创新具有专有权的期间。专利宽度定义了被专利主张和保护的技术领域——在技术空间中，竞争者不能在不侵犯专利的情况下提供竞争对手的创新——并且由创新者明确选择。经济学文献中的一个标准假设是，创新者应该总是选择申请最大的专利宽度，从而阻止其他公司的进入，从而使创新者获得垄断租金(见吉尔伯特、夏皮罗和加利尼的例子，这一观点)。然而，这种策略没有认识到专利常常在专利局或法院(Cornish)受到法律挑战。这一挑战的性质是，专利保护越广泛，该专利受到竞争对手合法挑战的可能性就越高，该专利将与另一项专利重叠，或法院将使其无效或缩小其范围(勒纳)。既然专利的广度经常受到挑战，那么问题就来了:创新者是否能够选择一个阻止进入的专利广度，或者创新者是否被迫与新进入者分享市场。摘要本文的目的在于探讨当创新企业所主张的专利宽度可能受到挑战时，创新企业应采取的最优专利宽度策略。本文在完全信息序列对策中确定了最优专利策略。游戏中的代理人是寻求专利保护并决定所要求的专利宽度的创新者和决定是否进入专利权人市场的潜在进入者，以及如果进入的话，在垂直差异化的产品空间中定位的潜在进入者。通过逆向归纳法得到了该对策的解——首先考察了进入者的问题，然后考察了创新者的问题。本文表明，在某些条件下，创新者可以利用专利宽度来阻止进入——当这是可能的，最优的专利策略总是阻止进入。这些情况发生在参与者的研发效率和试验成本值的某些组合下(即，低研发效率——导致高研发成本——和高试验成本)。当这些具体条件不具备时，创新者的最佳策略是允许新的竞争对手进入市场。当允许进入时，创新者选择专利宽度，这样更大的专利宽度所带来的产品差异化的好处与更大的专利宽度带来的更大的专利挑战的可能性相抵消。本文的结论之一是，只有当专利侵权对进入者来说不是最优策略时，创新者才会选择最大的专利宽度。这是在一组非常具体的条件下发生的(即，结合非常高的研发效率和试验成本价值)。