Could you describe the AGL method that enabled ultimate picture quality?
Taniguchi: Since 2009 Panasonic's flagship TV models have adopted a "One sheet of glass" design scheme, which has been highly evaluated. However, some people expressed concern that the front glass panel might sacrifice picture quality. Installation of a glass panel in front of the display panel creates an unnecessary air layer between the glass and panel. This air layer can cause double-images and other problems. For models leading up to the previous year's model, the VT50, we used a filter technology and the like to overcome the problems created by the air gap layer. When we decided to review all the related technologies once again, we decided to focus on the simple but most fundamental target of eliminating double-images. To pursue the ultimate picture quality, we had to consider removing the unwanted air gap layer between the display panel and glass panel. However, it was extremely difficult to physically get rid of the air gap layer. As a result, we opted for the AGL method. At the beginning, we racked our brains to figure out how we could reduce the air gap layer to zero and how we could achieve the highest possible picture quality after achieving the zero air layer. AGL stands for Air Gap Less, and the name "AGL method" was coined by us at the time the development started. This method uses a technology commonly referred to as direct bonding.
Masuda: It was our first attempt to use the AGL method for a large-screen TV. It was a very difficult method to employ. Needless to say, mass production was a prerequisite. So members expressed their concerns, such as whether the use of the AGL method would achieve the desired yield rate and whether it would enable us to maintain profitability. I was involved in the development of the actual method. In the beginning, even most of the development team members were not really positive about the method. What changed our mind was also the teamwork. For example, the hardware department and software department, which usually work separately in the past, collaborated closely in the development of the ZT60. I believe this collaborative approach raised our motivation and enabled us to overcome the difficulties. Taniguchi: Actually, development of the AGL method was initiated even before the ZT60 project. We began research and development of the AGL method near the end of 2009 as a possible means of improving picture quality in addition to its use for design enhancement. At that time, we wanted to complete the technology as soon as possible so we could incorporate it immediately in the development of new TV models. However, it was extremely difficult to bond the glass and the rigid panel without creating any air gap layer, and we were faced with repeated failures. We simply couldn't develop the method successfully. We kept trying and conducted numerous experiments. Before we succeeded, we had developed more than 20 material types for bonding material development and bonded more than 1,000 panels with unsuccessful results. After a few years had passed, we were able to see the prospect of commercial application of the AGL method. This coincided with the start of the ZT60 development. For many years, we went through the process of trial and error, without knowing the cause of our failures. But as soon as we discovered the cause, we believed that the method could be applied to mass production. We were thrilled to incorporate the new technology into actual products.
Masuda: It was our first attempt to use the AGL method for a large-screen TV. It was a very difficult method to employ. Needless to say, mass production was a prerequisite. So members expressed their concerns, such as whether the use of the AGL method would achieve the desired yield rate and whether it would enable us to maintain profitability. I was involved in the development of the actual method. In the beginning, even most of the development team members were not really positive about the method. What changed our mind was also the teamwork. For example, the hardware department and software department, which usually work separately in the past, collaborated closely in the development of the ZT60. I believe this collaborative approach raised our motivation and enabled us to overcome the difficulties. Taniguchi: Actually, development of the AGL method was initiated even before the ZT60 project. We began research and development of the AGL method near the end of 2009 as a possible means of improving picture quality in addition to its use for design enhancement. At that time, we wanted to complete the technology as soon as possible so we could incorporate it immediately in the development of new TV models. However, it was extremely difficult to bond the glass and the rigid panel without creating any air gap layer, and we were faced with repeated failures. We simply couldn't develop the method successfully. We kept trying and conducted numerous experiments. Before we succeeded, we had developed more than 20 material types for bonding material development and bonded more than 1,000 panels with unsuccessful results. After a few years had passed, we were able to see the prospect of commercial application of the AGL method. This coincided with the start of the ZT60 development. For many years, we went through the process of trial and error, without knowing the cause of our failures. But as soon as we discovered the cause, we believed that the method could be applied to mass production. We were thrilled to incorporate the new technology into actual products.
What caused the failures?
Taniguchi: It was simple. Air bubbles. Air bubbles cause problem. Air bubbles were generated between the bonded glass and panel. It was not easy to fine the way to remove the air bubbles. For example, imagine fixing a clear protective film onto the LCD of a smartphone without any air bubbles generated between them. If you've ever tried it, you know how difficult it would be to bond a 60-inch sheet of solid glass to a panel without leaving any air bubbles between them. Even when we bonded them cleanly, air bubbles were generated later on the bonded surfaces. That was a difficult problem to solve. It troubled us from the start of our development activities until right before we successfully achieved commercialization. When we discovered the cause of the air bubbles and figured out how to solve the problem, all our worries and anxieties suddenly disappeared. It was such a nice feeling.
What were the difficulties caused by the large panel size?
Masuda: First, it was difficult to set up the equipment for stable production. A large panel tends to distort and makes bonding difficult. Slight distortion may not cause much trouble when the panel is as small as the LCD on a smartphone, but it becomes a major obstacle when the panel is 60 inches in size.
Taniguchi: In our verification test, we started with a display panel and glass panel about the size of an A4 sheet of paper. Then, we gradually increased the size. When the size exceeded 40 inches, it became increasingly difficult to achieve zero air bubbles. Because we didn't have the facility experiments with large-size glass sheets, we sought the cooperation of a factory in Japan that specialized in processing glass. It was the first time for that factory to handle glass sheets integrated with electronic modules, so I am sure our request was not easy to fulfill. The glass processing company aligned with our goal of "creating the ultimate picture quality," and worked earnestly with us in the development. I went to the factory frequently from our development base in Kadoma. During the final stage of development, I probably spent 80 or 90 days out of the year at the factory. Then, our long-cherished goal became a reality. We were able to bond the display panel and glass panel without generating any air bubbles between them and also suppressed the generation of air bubbles after bonding. We were extremely excited.
Taniguchi: The production method for the ZT60 is completely different from that for previous plasma TVs. For the ZT60, we did things we avoided doing before because of potential risk. We were determined to achieve our goal, though, and never gave up.
Taniguchi: Bonded panel sets are very delicate, and we had never experienced problems like these during the development of conventional TVs.
Taniguchi: We took a different approach in developing the ZT60. It's important to continue tackling challenges even if they're considered to be extremely difficult by most people. I'd like to maximize our recent development experience in future manufacturing activities.
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