Hibino Corp has developed the "LumixxLine" rope type LED display that can be attached to curved surfaces such as a cylinder and began its sales Nov 20, 2007.
When forming a screen, multiple LumixxLines, which align so-called 3-in-1 LEDs that contain red (R), green (G) and blue (B) LED chips in one package at intervals of 35 or 70mm, are lined up side by side like floor boards. One line consists of 96 LEDs (pixels) and one control unit can manage 16 lines.
Up to 9 control units can be used in combination through cascade connection. In that case, a screen can render images using a maximum 144 lines, which is a resolution of 96 x 144.
At maximum, a screen measures 20m2 (equivalent to a 252-inch display) with 35mm-pitch lines (one line is 3,964mm long) and 74m2 (490-inch) with 70mm-pitch lines (7,324mm).
This LED display can show video at locations, where the installation of existing flat LED displays has been difficult. The LED display can be wrapped around a cylinder, spread over stairs or attached to a store's show window like a bead curtain, for example. Nikkei Electronics interviewed Hibino about the background of the LumixxLine development and the technology.
Q: Tell us what triggered you to develop the rope type LED display.
Hibino: Having been engaged in LED displays, we have a plenty of opportunities to provide LED displays for their use at event exhibition booths. Accordingly, many of our LED display clients are involved in events and give us many chances to hear opinions about presentation using LEDs.
Among those opinions, some started to ask for not only existing flat displays but also flexible LED displays that use rope-like devices. We commenced development about two years ago. We are currently receiving inquiries and we expect LumixxLine to start emerging in early 2008.
Q: What difficulties did you experience during the development?
Hibino: Our LumixxLine is not a lighting ornament, but a display that renders images. We therefore wanted to make the display render images at high quality. As the display shows images on a screen made of lined-up, rope-like LED displays, spaces between the ropes are sometimes not even depending on installation techniques.
For example, images might be shown on a screen, which broadens from up toward the bottom or twisted with ropes crossed over one another. We have introduced an image processing technology to render images with little distortion even under such circumstances.
As for displayed colors, the display controls each of RGB at 12 bits. Featuring a processor supporting up to 4K2K video, the control unit that connects the LumixxLines controls images shown on the LED display.
Q: Minimum pixel pitch is 35mm. Why did you choose 35mm pitch?
Hibino: We set minimum pixel pitch at 35mm considering a relation between flexibility and the LED substrate. The pixel embedded with the rope houses a printed substrate incorporating a 5.5 x 5.5-mm surface mount LED and a LED driver IC. The printed substrate is 17 x 17mm. Pixel units containing this printed substrate are aligned on a cable coated with rubber. To make the rope flexible, 35mm pitch was optimum. If the pixel pitch was shorter, the flexibility would be damaged and the contrast with flat displays would be weaker.
We, however, can double the resolution. If the ropes are aligned so that LEDs can form hound's tooth check, the pixel pitch will be halved. For the new LED display, we employed image processing software that assumes hound's tooth check alignment.
Q: How much is the LED display's power?
Hibino: The rated power of one LED display line is 500W. This is power consumption when all the LEDs are completely lit, therefore, it may lower 30 to 40% when actually rendering video.
Each pixel is designed to more efficiently radiate heat from the LED. Accordingly, LED displays can be built without adopting a special radiator component. Surface luminance of the 35mm- and 70mm-pitch models is 2,000cd/m2 and 500cd/m2, respectively.
Each pixel is supplied with 5V from a power source. The LED driver IC embedded with each pixel generates the voltage supplied to the LED using these 5 volts.
Q: From what company are you purchasing LEDs?
Hibino: We purchase LEDs from Nichia Corp. We use Nichia's LEDs in our flat LED displays as well. The surface mount LED employed for the LumixxLine is roughly categorized into multipurpose models, but its RGB emission colors are arranged to meet our specifications.
Q: How much are they?
Hibino: A system that can form a 20m2 screen with the 35mm-pitch model is priced at ¥33 million. Another system that can form a 74m2 screen with the 74mm-pitch model is priced at ¥40 million. This system includes 9 control units as well as the LumixxLines.
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