MINOLTA Corporation

Coverage & statement = Yuko Sakurai

There may be various reasons for wearable computers not prevailing well, and seems to be the intolerance to head mounted display (HMD). How would people react if the shape of HMD were just the same as glasses and not the shape of goggles or something in science fiction films?

Weighs Only 25 g, No Uncomfortable Feeling

¡ÈHolographic See Through Display¡É developed by MINOLTA is an epoch-making futuristic display of which shape is almost the same as glasses. A small unit is assembled on top of the lens, but it is not so visible with certain hairstyles. It weighs only 25 g without cables and the thickness of a prism equipped on the lens is only 3.4 mm, which means its appearance and comfortableness the wearer feel are not inferior to those of glasses.

Input and output ports are attached to cables assembled along the rim of glasses, and I watched CG and animation by connecting them to the video cartridge recorder when we visited the company. The image shown on the lens is only one-colored (green), and its size is about one-fourth as large as the lens surface, but it gave me the impression as if I was watching an image on 20-inch TV screen. There was no feeling of oppression of the lenses to obscure my view.

The screen resolution is QVGA of 320 by 240 dots per inch. The resolution is not high enough to enjoy movies or check icons on personal computers, but watching TV monitor and captions is perfectly fine. Angle of view (What angle we can watch at) is 14 degrees horizontal, and eye diameter (How wide we watch) is 3 mm. The eye diameter of 3 mm means that the screen goes out of the vision when we shift our focus by more than 1.5 mm. This indicates that monitoring the screen is not so annoying.

One of the reasons for succeeding in miniaturizing HMD compared to the conventional type is that they narrowed the angle of view and eye diameter. Of course, there is more than that.

Hologram And Prism as The Keys

According to Mr. Hiroaki Ueda, Chief of Input and Output Technology Department, Image and Information Technology Center, MINOLTA, the trick was the combination of hologram and total reflection prism to make the display thin and small this much leaving the user¡Çs vision undisturbed. ¡ÈOne of the characteristics of holograms is that they work just like concave mirrors even when they are flat, in short, they can enlarge images on the flat surface. And another characteristic is its transparency.¡É

Image data displayed on the liquid crystal monitor of the unit above the glasses are sent to the hologram optical element installed athwart to the position of a user¡Çs eyes using the total reflection prism. When the data reaches the surface of the hologram, it is reflected toward the eyes as it gradually expands. These phenomena have been known in principle, but no one had ever practically used it.

¡ÈWe have already produced the glasses with color display. If they are practically used, we will be able to watch TV in the commuter trains and read digital newspapers. It will be easier to read e-mails on the colored display than the display of cell phone.¡É

Anyway, the appearance of this display may be good news for those who would like to use wearable computers without standing out in a crowd.

However, its sale date has not been decided yet. It is going to be a wait until the appearance of killer applications to be accepted in the common market by and appreciated by everyone.