1. Line Lighting Fixtures for “Red Rooms”
A variety of 19th century French masterpieces are on display in the large “Red Rooms” that has impressive red walls, of which Jacques Louis David's “the Consecration of the Emperor Napoleon and the Coronation of Empress Josephine” is representative. The paintings in the “Red Rooms” have been illuminated by natural light and metal halide lamps up until now, but the uneven distribution of light through the glass ceiling above the gallery has been a factor that detracts from the ambiance of the gallery.
Therefore, the people at Toshiba proposed the use of “straight tube type LED base lights” which are starting to be adopted for office lighting in Japan. However, with conventional fixtures, the fixture needs to be disassembled in order to connect the power source to the terminal inside the fixture, resulting in the possibility that screws or nuts may be dropped when the fixtures were installed. In addition, there was the drawback that the power line that connected fixtures together needed to be run outside the fixture in order to turn on multiple fixtures at the same time. The Louvre Museum was concerned that the falling of a screw or nut could cause breakage of glass, and this may result in injury to the many visitors to the museum. In addition, the Louvre Museum pointed out that they did not want to have a power cable outside the fixtures since the cable may create a shadow on the glass ceiling. Furthermore, the Louvre Museum said that they wanted to have the size of the fixture reflective plate be made compact in order to allow the entrance of the maximum amount of natural light into the gallery, and uniformly illuminate the glass ceiling while reducing the number of fixtures that were to be installed.
In order to respond to these problems and requests, we first provided a terminal on the outside of the fixture to connect the power source cable so that the fixture did not need to be disassembled. We then made a revision to the fixture design so that the cable connecting fixtures with each other could be routed inside the fixtures, preventing a shadow of the cable from being created on the ceiling. After this, we developed a clip type system to secure the fixture that does not use screws or nuts, allowing one-touch mounting of the fixtures on the Louvre Museum structure. In addition, we developed a compact reflective plate that is highly reflective and straight tube LED lamps featuring high efficiency and high colour rendering, making the size of the fixtures compact and reducing the number of fixtures required.
Furthermore, Toshiba incorporated a DALI control compatible power source for the first time in Europe, with which the brightness of the lamps is immediately modified in response to lighting intensity sensors installed in the gallery in accordance with changes in the natural light due to the time of day or weather.
The lights for the “Red Rooms” that were created together with the Louvre Museum through this process illuminate the pictures with light that is free from unevenness, while achieving a 60% reduction in total fixture power consumption and 72% reduction in total fixture weight.
2. Mona Lisa Spotlight
The “Mona Lisa” is the world famous painted portrait by Leonardo Da Vinci that is said to be representative of the Renaissance. Leonardo Da Vinci used a shading technique called sfumato, perspective and other innovative painting techniques in the “Mona Lisa”, which had a large impact on portraits that were painted after this. However, convex deformations have appeared in the thin wooden panel on which the “Mona Lisa” is painted during the five centuries since the painting was made, resulting in cracks in the painting, and the protective film on the painting has oxidized, giving the colours in the painting a blackish or yellowish tinge. In addition, since the painting is covered with a greenish protective layer of glass for security reasons, the painting was in a condition in which the visitors to the Louvre could not appreciate the brushwork of the artist or the skillful use of different colours. We were asked to alleviate this situation so that the brushwork or the artist and skillful use of different colours can be appreciated.
In order to effectively respond to this request, we developed a spotlight that has the capability to freely change the lighting intensity, correlated colour temperature and colour deviation on the painting, and achieves a maximum average colour rendering index (CRI) of 98 which indicates the light is very close to natural light. We then developed an optical system that is capable of illuminating only the “Mona Lisa” painting and achieving uniform lighting intensity distribution that is free from colour unevenness.
This resulted in the completion of a spotlight in which the lighting intensity, correlated colour temperature, colour deviation can be set in a short period of time in order to maintain a high colour rendering index. We then implemented measures to obscure the cracks on the surface of the painting which have been an issue from the beginning, as well as offset the earthy colours and the greenish colour of the protective glass in order to reproduce the appearance of the “Mona Lisa” as it was painted in the 16th century.
During this “Mona Lisa” lighting renovation project, we needed to cooperate with engineers from Germany, Russia, France and other countries who have worked on the lighting in the past. I would like to express my appreciation to everyone who was involved. As an engineer, it was a great honor to be able to participate in a project in which people from various countries around the world worked together on behalf of Leonardo Da Vinci to preserve the “Mona Lisa”, a global masterpiece, for the enjoyment of generations to come.