Hitachi DX07

TheHitachi DX07is a 2.9 inch (73 mm)liquid crystal displayscreen which went into mass production in December 2006:

• 62mm x 37mm
• 800x480pixels
• 1.677 million colours
• 400:1contrast ratio
• 250cd/m²
• IPS TFT(in-plane switching)

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 onlydither1.62 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" visionusing 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 forNTSCDVBcontent (720x480 pixels)
• Smallest hand held screen without loss of detail for NTSCDVDcontent (720x480 pixels)

Notes:

• "Normal" visionis when someone can distinguish detail at 1/60 of adegree(anarcminute)
• Theclosesta hand held screen can comfortably be viewed is 250mm (approx. 10 inches)

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 acomfortable 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 wouldditherin 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 latesthigh-definition videoscreen, 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)

External links

• Hitachi DX07 press release (English)
• Hitachi DX07 press release (Japanese)
• BeHardware's Test: the influence of electronic components on LCD colors