1. Field of the Invention
The invention relates to a display device and a display method.
2. Background Art
Among non-luminous display devices, there is a display device that combines a color filter that absorbs light of a specific wavelength and a light switch layer of liquid crystal and the like. In such a display device using a color filter, since the light of the specific wavelength is continually absorbed, the device has low light use efficiency and limitations on obtaining bright display. In particular, this low light use efficiency is a serious problem in the case of reflection-type display devices that do not use a specific light source such as a backlight.
A display device in which the wavelength of light to be absorbed can be controlled by, for example, an electric signal is expected to achieve display without using a color filter. For example, by using a localized surface plasmon which can be excited with visible light, the resonance wavelength can be shifted by an electric signal from the outside to control the wavelength of the light to be absorbed, and thereby colors of the entire visible region can be displayed.
For example, a display device is presented that deposits particles of a metal ion by an applied electric field and thereby generates plasmon absorption (see JP-A 2007-240668 (Kokai), for example). Further, an image formation means is presented in which particles having plasmon color-developing capability which take charge in different polarity are moved by an applied electric field (see JP-A 2006-349768 (Kokai), for example). However, these methods require large energy to deposit or move particles, and further have a problem with a response speed.
Further, a display device is presented that combines: a color separation optical element such as a prism and a diffraction grating; a refractive index changing layer; and a plasmon-generated light emitting means (see JP-A 2003-107441 (Kokai), for example). However, this method requires the color separation optical element, and therefore has a complicated configuration.
On the other hand, it is reported that, if a metal nanoparticle is immersed in a solution containing an anion and electrophoresis is performed by an applied voltage to adhere the anion to the metal nanoparticle, a resonance wavelength of a localized surface plasmon of the metal nanoparticle shifts (see J. Electrochem. Soc. 146, p 628 (1999), for example). However, according to this method, the shift amount of the resonance wavelength is approximately 10 nm (nanometers) at most, which is insufficient to be used for a display device.