Report on the development of a back-illuminated ToF image sensor to meet growing demand in the future
Sony remains a leading company in the area of image sensors.
Forecasts suggest that needs in the area of sensing applications will expand, adding to the demand already building up in the imaging applications.
Transcending barriers such as country of residence, culture, areas of responsibility and differences in experience, the technologies and ideas generated by Sony's diverse human resources continue to create breakthroughs in the area of sensor development. We spoke to some of the engineers in charge of developing back-illuminated ToF image sensors, which feature the very latest distance imaging technology.
Yamazaki: The back-illuminated ToF image sensors (ToF sensors) we have developed represent the fusion of technology from a group company in Belgium that specializes in ToF design and development, and image sensor technology created to date by Sony. These sensors are capable of measuring distances from short-range to long-range with high precision.
Ohashi: This sensors are built into the entertainment robot "aibo" to prevent it from bumping into obstacles or falling over on uneven surfaces. ToF sensors are also used in smartphones and other mobile devices. They are useful in sensing the distance to an object in order to achieve bokeh (out-of-focus blur) effects in digital photography, as well as 3D imaging of objects and high-precision face recognition.
Moriyama: Over 100 engineers divided into various areas work on the development of a single sensor. In the case of the ToF sensor especially, the range of technologies involved is much broader than in the case of a single sensor unit, extending from the laser light source to the signal processing that converts the detected optical information into distances. If we include the human resources that were involved in this development process the total could reach 200-300 people. These many engineers formed a team and pooled their technical knowledge to create ToF sensors.
Yamazaki: When we encounter something that we don't understand at work, we normally consult the relevant department. The culture at Sony, however, encourages engineers to speak directly to specialists with highly technical knowledge throughout the entire Sony Group. Whenever a problem arises, we gather members irrespective of department or group company together in any available space to engage in outspoken discussions. Since the extensive introduction of teleconferencing systems and online conferencing, people are no longer constrained by whether they are currently at head office or on a business trip, greatly facilitating discussions. People brought their own ideas and endeavored to do their best through discussions, leading to daily breakthroughs as they rapidly picked up new insights.
Moriyama: Since ToF sensors were a totally new area for us, we felt we were groping in the dark in the initial phases of development. However, the initiative shown by individual project team members in putting forward ideas and acting proactively provided the momentum we needed for progress. Sometimes, when we ran into major obstacles, we were unable to come up with solutions no matter how many meetings we held. However, remembering that other group companies were engaged in ToF sensor research for other applications, we were able to open up new avenues on the basis of useful advice from the people in charge. I'm convinced that one of Sony's greatest strengths is a corporate culture that encourages easy discussions irrespective of segmentation into teams, departments or group companies.
Yamazaki: This project brought together people with wide-ranging backgrounds and expertise. I majored in chemistry at university and had never studied semiconductors. Moreover, I was assigned to semiconductor marketing when I joined the company. Today, I am in charge of deciding on the sort of specifications and promotions we should propose to customers. This means the experience and the ability to constantly take the customers' viewpoint that I acquired during my marketing days are still useful.
Baba: My major at university was also totally unrelated to semiconductors as I was involved in research into robotics. I'm currently engaged in creating evaluation boards for ToF sensors. These evaluate the total system as modules that include lasers and lenses, not just the sensor as a single unit. The module is like a small robot because it incorporates both mechanical and electrical parts into a single unit. My current work suits my character well because it enables me to evaluate entire systems using the electrical and mechanical knowledge I gained from robotics.
Ohashi: I am currently in charge of fine-tuning ToF sensors installed in mobile devices for various applications, and provide the signal processing development team or the systems development team with feedback on any issues that may arise. As I researched signal processing at university and was put in charge of semiconductor systems after I joined the company, I do my best to provide appropriate feedback based on the knowledge I gained in both areas.
Moriyama: I have been doing research on semiconductors since my university days, but was assigned to developing image sensors for SLR and other interchangeable lens cameras after I joined the company. For a time after I first joined my current department, I was troubled by the fact that my approach to developing image sensors that could check the performance ToF sensors for face recognition was not satisfactory. I was helped at the time by advice from someone who had experience in developing face recognition technology at another company. I was also greatly helped by the perspectives and knowledge of experts in spatial perception and mathematics. I really felt that at Sony, sensor development is underpinned by people from various backgrounds.
Yamazaki: We are developing ToF sensors in cooperation with a business center in Belgium, but we were constantly confused to begin with. In addition to the language barrier, the culture over there values balance. Key personnel would take long vacations midway through the development process, something that would be unthinkable in Japan when it comes to scheduling. On the other hand, Belgium is surrounded by other countries so people are used to working in multicultural environments and many of them are very curious about foreign cultures. They are ready to understand and accommodate Japanese thinking and culture.
Moriyama: It is true that we have many opportunities to come into contact with various languages through such initiatives as "A word for today," which entails someone voluntarily compiling a list of multilingual translations of certain words each day. Things like this make me feel that people are willing to accept different cultures proactively. Belgian members of the team are deeply knowledgeable about signal processing and software development. They adopt a multi-perspective approach to proposing ideas when developing the hardware for image sensors, thereby ensuring that people mutually complement each other in their areas of expertise. This is also one of Sony's strengths.
Ohashi: A certain problem was raised during a visit to Chinese customers together with team members from Belgium. In Japan, we would usually take the problem back and return with proposals later, but the team members wrote some source code on the spot and suggested we go ahead and try it. That is the way to make rapid progress in work. This was something we could not have done ourselves, and it satisfied the needs of our Chinese customers, who seek rapid responses. When dealing with Korean customers, however, a different approach is necessary. In order to respond flexibly to customers from many different countries, it is vital to accept their different cultures and create solutions that suit them.
Baba: Recently, there has been a lot of talk about how AI and self-driving vehicles may become a normal part of our lives. I believe this will steadily increase the need for sensing technologies that can detect data from the outside world, especially distance sensing. Given the situation, I think developing ToF sensors will help resolve future social problems and plan to ensure it will become one of Sony's core businesses. Since engineers involved in development are required to be expert in various areas, I personally want to be able to speak on equal terms with specialists with expertise in different specialties.
Ohashi: Adding high-precision long- and short-distance sensing technologies to imaging technologies will add various new functions to sensors, opening up a wide range of new possibilities. Using them in gesture controls for automobiles as well as installing them in robots and smartphones encourages high expectations of applying them in VR and AR. I am pretty sure than sensing will be even more interesting going forward. I learned many things for the first time while developing ToF sensors, and came into contact with development and business thinking in countries with different cultures, like Belgium, China and Korea. Looking ahead, I want to broaden my own horizons through such activities while developing high quality sensors.
Moriyama: Sony Semiconductor Solutions Group's mission is "To spark imaginations and enrich society through the power of technology." I believe that sensing's strength is that it adds "appeal," "enjoyment" and "convenience" to these aspirations, and is a key technology for contributing to society. To ensure technology reaches its full potential, we must continue to take up even greater challenges going forward. While I am currently focusing on ToF sensor development, I intend to work on offering even better sensor solutions by incorporating various other technologies.
Yamazaki: Integrating new sensing technologies in addition to distance detection will expand sensor capabilities dramatically. Looking ahead, sensors will almost certainly be introduced into services such as automated stores and vending machines, not just technological solutions and systems. I believe their use will expand into self-driving vehicles, robots and drones in the fairly near future, but they are also likely to find a wide range of applications in areas that we cannot yet imagine. When the ToF sensor business first started up, I felt it would need knowledge from completely different areas that we had never envisaged before. I am determined to acquire various kinds of knowledge from a wide range of areas in order to present the world with sensors that will make our lives richer and more comfortable.