# Hitachi DX07

The Hitachi DX07 is a 2.9 inch (73 mm) liquid crystal display screen which went into mass production in December 2006:

Each pixel is therefore 78µm x 77µm (1µm = 1/1000mm).

Note: It's also safe to assume that this is an 8-bit per channel display (a 6-bit per channel display can only dither 1.62 million colours)

## Optical Properties of the DX07

The DX07 has a number of interesting properties related to its small size and high resolution. The following are true for someone with "normal" vision using this screen as a hand held device:

• Smallest pixel size to comfortably view a hand held device without loss of detail
• Smallest hand held screen without loss of detail for NTSC DVB content (720x480 pixels)
• Smallest hand held screen without loss of detail for NTSC DVD content (720x480 pixels)

Notes:

## Smallest Visible Pixel Size for a Hand Held Device

The smallest visible pixel size (p) for a hand held device can be calculated assuming the screen is held at a comfortable distance (250mm) for someone with "normal" vision (able to see detail at a 1/60 degree angle):

$p = 250 \cdot sin\tfrac{1}{60} \approx 0.0727mm = 72.7\mu m$

It can therefore be concluded that the pixel size for the Hitachi DX07 screen is only 5% greater than the smallest possible for practical use.

Note: Smaller pixel sizes would dither in much the same way as printed dots (72.7µm is approximately 350dpi)

## Other Hand Held Screen Sizes

If other hand held devices were manufactured for the latest high-definition video screen, then their smallest sizes without loss of detail (i.e. 72.7µm pixels) would be as follows:

Format Pixels Screen Size Diagonal
DV NTSC 480x720 35mm x 52mm 63mm (2.5 inches)
PAL 576x720 42mm x 52mm 67mm (2.6 inches)
720p 720x1280 52mm x 93mm 107mm (4.2 inches)
1080p 1080x1920 79mm x 140mm 160mm (6.3 inches)