At first, my idea was to create a small standalone panel that could be easily carried in a backpack or pocket. The LED matrix determines the size of the device. Therefore, it was important to select compact LEDs that offer excellent brightness.

The original matrix was 64x8 pixels: 2.1 x 2.1 mm LEDs at 1.6 mm apart. However, that size made the device non-portable. Here’s a comparison picture with our current, smaller prototype.

During the selection process, we targeted LEDs smaller than 2 mm for a denser matrix and a more compact device. After considering options based on size, brightness, and cost, we prepared a comparison table for mass production.

We used a specially designed board to assess the brightness and color rendering of the selected LEDs: 8x8 pixel matrices for the selected LEDs, covered by a 25% transparent tinted film. We displayed various characters to compare brightness and color. LED No.2 was the brightest, but at a kit cost of $50, the retail price for a single BUSY Bar would start at $400. It does not work for us. LED No.1 was also bright and compact, but similarly unaffordable.

Upon reviewing, we focused on options 4 and 5, differing in size and brightness. Eventually, option 4 was chosen, favoring size over brightness. After some bargaining with the manufacturer, we secured a $4 price for 1152 pieces. Having decided on LEDs, we can move forward to changing the design of BUSY Bar.

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