According to Chesbrough (2003, 36) a fundamental shift has emerged in how companies generate new ideas and bring them to market. In the old model of closed innovation, firms adhered to the following philosophy: Successful innovation requires control, in other words, companies must generate their own ideas that they would then develop, manufacture, market, distribute and service themselves (see Figure below).

Toward the end of the 20th century, Chesbrough (2003, 36) points out two fundamental changes which have occurred radical changes in the notion of closed innovation:
…the dramatic rise in the number and mobility of knowledge workers, making it increasingly difficult for companies to control their proprietary ideas and expertise. Another important factor was the growing availability of private venture capital, which has helped to finance new firms and their efforts to commercialize ideas that have spilled outside the silos of
corporate research labs.
Sawhney (2002, 26) analyzes the alteration propounded by Chesbrough; ‘the innovation challenge has become how to best identify and use the knowledge that’s available both within and outside the company’.
Gallagher and West (2006, 319) define ‘open innovation as a powerful framework encompassing the generation, capture, and employment of intellectual property at the firm level.’ They identify three fundamental challenges for firms in applying the concept of open innovation: finding creative ways to exploit internal innovation, incorporating external innovation into internal development, and motivating outsiders to supply an ongoing stream of external innovations. Motivating outsiders to supply external innovations might be difficult, and Gassman and Gaos (2004) instead highlight the need for firms to identify such external ideas by using technological listening posts as a mean of technological knowledge sourcing. Later on Chesbrough (2003, 36-37) introduces the model of open innovation; ‘commercialization of external (as well as internal) ideas by deploying outside (as well as in-house) pathways to the market.’ (See Figure below)

Chesbrough (2004, 23) states that: Firms can and should use external as well as internal ideas and internal and external paths to market, as they look to advance their technology. Open Innovation assumes that internal ideas can also be taken to market through external channels, outside a firm's current businesses, to generate additional value.
Chesbrough and Schwartz (2007, 55) further explain the open innovation concept:
Traditional business models center around the idea of developing a product from internal technology (R&D) and then producing, marketing and selling that product one selves. Whereas the use of partners in the research and/or development of a new product or service creates business model options that can significantly reduce R&D expense, expand innovation output, and open up new markets that may otherwise have been inaccessible.
Van der Meer (2007) argues that an open innovation system requires a different way of thinking - different set of norms, beliefs and values. This claim is backed up by King et al. (2003, 600) in that: Given the “not-invented-here” emphasis that prevails in many firms, managers may not be naturally inclined to augment their firms’ internal resources with complementary, externally acquired resources. Such a bias may predictably decrease a firm’s ability to regularly appropriate rents from technological innovations. King et al. (2003, 600) argue that managers should be ‘receptive to obtaining from external sources the resources needed to create or exploit technological innovations’. Kirschbaum (2005, 24) claims that ‘innovation is a culture not a process’ and ‘successful, profitable innovation depends upon teamwork and an entrepreneurial culture’ by ‘combining internal and external competencies and knowledge, both in R&D and marketing’. Kirschbaum (2005,25) describes the successful approach of the Dutch company DSM - its ‘open innovation model for creating and nurturing new businesses involves the continuous appraisal and testing of ideas, projects and businesses until they are fully developed, spun off or rejected’. Gassmann (2006, 224) also suggests that:
Open innovation includes various perspectives: globalization of innovation, outsourcing of R&D, early supplier integration, user innovation and external commercialization and application of technology. Chesbrough and Crowther (2006, 229) further define inbound open innovation as ‘leveraging the discoveries of others’, and outbound open innovation as ‘looking for external organizations with business models that are better suited to commercialize a given technology’ Chesbrough and Crowther (2006, 235) further clarify that ‘the concept of open innovation ought not to be interpreted to imply the outsourcing of the entire R&D function’. Huston and Sakkab (2006, 62) adds substance to this, explaining that Proctor and Gamble’s open innovation model “Connect and Develop”; ‘ it is about finding good ideas and bringing them in to enhance and capitalize on internal capabilities’, and they stress that it was ‘crucial to know exactly what we were looking for’. As far as technology is concerned, Dodgson et al. (2006, 344) discuss in their study of Procter and Gamble’s approach towards open innovation that ‘as well as improving the company’s receptivity to external inputs into its innovation activities, technology also assists internal “openness”, by helping build effective communications between disparate groups in the company’. Actually, this is in accordance with Gassmann’s idea (2006, 225) which ‘by cooperation with external partners, many of a company’s orthodoxies – basic values and beliefs – are questioned, thus enabling breakthrough thinking’. In addition open innovation increases the extent of business and technological interdependencies between firms. Chesbrough (2007a, 25) states further on that open business models enable an organization to be more effective in creating as well as capturing value. These models also allow greater value capture by utilizing a firm’s key asset, resource or position not only in that organization’s own operations but also in other companies’ businesses. Sawhney et al (2007) argue that if all firms in an industry are seeking opportunities in the same places, they tend to come up with the same innovations. Thus, viewing innovation too narrowly blinds companies to same opportunities and leaves them vulnerable to competitors with broader perspectives. They define business innovation as the creation of substantial new value for customers and the firm by creatively changing one or more dimensions of the business system. When Christensen et al (2005, 1536) talk about the industrial dynamics of open innovation in the case of consumer electronics, they suggest that there will always be a level of “closedness” in innovating firms depending on how large a portion of the overall value they strive to appropriate and there need not be a consistent linear movement from closed towards open styles of innovation: A highly extrovert innovation strategy that is considered necessary for managing and controlling a technological discontinuity in the early stages of a new technology, is succeeded by a much more closed strategy in the subsequent rounds of follow-up innovations as the technology becomes more matur (Christensen et al. 2005, 1558). Similarly Kirschbaum (2005, 24) describes the successful approach of the Dutch company DSM emphasizing that ‘different management styles are required, ranging from a scientific approach in the early stages, to an entrepreneurial attitude in the early phase of commercialization, to a more risk-adverse mindset once the business has matured.’ These studies seems to confirm Chesbrough and Crowther’s (2006, 229) view that many companies on the market today are recognizing that ‘not all good ideas come from internal sources’. However, Chesbrough and Crowther’s (2006, 229) also stress upon that ‘not all good ideas can be successfully marketed internally.’ In this point Chesbrough (2007a, 22) states ‘one company develops a novel idea but does not bring it to market. Instead, the company decides to partner with or sell the idea to another party, which then commercializes it’. Companies yield by ‘allowing unused internal technologies to flow to the outside, where other firms can unlock their latent economic potential’:
The firm no longer restricts itself to the markets it serves directly. Now it participates in other segments through licensing fees, joint ventures and spinoffs, among other means. These different streams of income create more overall revenue from the innovation. (Chesbrough 2007a, 24) The concept of outbound open innovation that Chesbrough and Crowther (2006) use and later developed by Chesbrough (2007a) further conceptualized by Lichtenthaler (2007a, 67), who states that ‘product marketing and licensing are a complement to the firm rather than a substitute in technology exploitation’. Lichtenthaler (2007b) finds differences between external technology exploitation and internal innovation by arguing that ‘efficiency is essential in internal innovation, but it is less important in external technology exploitation’. He suggests that ‘the data point to managerial deficits in planning and intelligence, which are considered the greatest challenges of successful external technology exploitation’ and therefore calls for ‘competence-based approaches to organizational boundaries’. Further, Lichtenthaler (2008) states that to leverage ‘technology assets in the presence of markets for knowledge’, it’s often a case that ‘technologies are simultaneously applied inside the firm and transferred across firm boundaries’. As a result ‘companies have to develop integrated strategies that facilitate ‘keep and-sell’ approaches to technology exploitation’ and that such ‘dynamic capabilities may constitute an important source of competitive advantage’. Chesbrough (2003) presents a useful comparison to summarize the debate between the closed and open innovation (See Table below).

References:
Chesbrough, H. (2003)’ The Era of Open Innovation’, MIT Sloan Management Review, Vol. 44, No. 3, pp. 35-42.
Chesbrough, H. (2004) ‘Managing Open Innovation’, Research Technology Management, Vol. 47, No. 1, pp. 23-26.
Chesbrough, H. and Crowther A.K. (2006) ‘Beyond high tech: early adopters of open innovation in their industries’, R & D Management, Vol. 36, No. 3, pp. 229-236.
Chesbrough, H. and Schwartz, K. (2007) ‘Innovating business models with co-development partnerships’, Research Technology Management, Vol. 50, No. 1, pp. 55-60.
Chesbrough, H. (2007a) ‘Why Companies Should Have Open Business Models’, MIT Sloan Management Review, Vol. 48, No. 2, pp. 22-28.
Christensen, J., Olesen, M. and Kjaer, J. (2005) ‘The industrial dynamics of Open innovation – Evidence from the transformation of consumer electronics’, Research Policy, Vol. 34, No. 10, pp. 1533-1549.
Dodgson M., Gann D. and Salter A. (2006) ‘The role of technology in the shift towards open innovation: the case of Procter & Gamble’, R&D Management, Vol. 36, No. 3, pp. 333-346.
Gassmann, O. and Gaos, B. (2004) ‘Insourcing Creativity with Listening Posts in Decentralized Firms’, Creativity and Innovation Management, Vol.13, No. 1, pp. 3-14.
Gassmann, O. (2006) ‘Opening up the innovation process: towards an agenda’, R&D Management, Vol. 36, No. 3, pp. 223-228.
Huston, L. and Sakkab, N. (2006) ‘Connect and Develop: Inside Proctor & Gamble’s New Model for Innovation’, Harvard Business Review, Vol. 84, No. 3, pp. 58-66.
King, D.R., Covin, J.G. and Hegarty W.H. (2003) ‘Complementary Resources and the Exploitation of Technological Innovations’, Journal of Management, Vol. 29, No. 4, pp. 589-606.
Kirschbaum, R. (2005) ‘Open innovation in practice’, Research Technology Management, Vol. 48, No. 4, pp. 24-28.
Lichtenthaler, U. (2007a) ‘The Drives of Technology Licensing: An Industry Comparison’, California Management Review, Vol. 49, No. 4, pp. 67-89.
Lichtenthaler, U. (2007b) ‘Externally commercializing technology assets: An examination of different process stages’, Journal of Business Venturing, forthcoming 2008.
Lichtenthaler, U. (2008) ‘Leveraging technology assets in the presence of markets for knowledge’, European Management Journal, forthcoming 2008.
Sawhney, M. (2002) ‘Managing Business Innovation: An Advanced Business Analysis’, Journal of Interactive Marketing, Vol. 16, No. 2, pp. 24-26.
Sawhney, M., Wolcott, R.C. and Arroniz, I. (2007) ‘The 12 Different Ways for Companies to Innovate’, MIT Sloan Management Review, Vol. 47, No. 3, pp. 75-81.
Van Der Meer, H. (2007) ‘The Dutch Treat: Challenges in thinking in business models’, Creativity and Innovation Management, Vol. 16, No. 2, pp. 192-202.
West, J. and Gallagher, S. (2006), ‘Challenges of open innovation: the paradox of firm investment in open-source software’, R & D Management, Vol. 36, No. 3, pp. 319-331.