Mobile video LCD FAQ
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VP Electricity
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From: Portland OR US
Mobile video LCD FAQ
Knew I had this somewhere...
LCD FAQ's
I want the highest resolution I can get, right? Well, if all other things were equal - but they aren’t. Shopping for a PC monitor and for mobile video are very different things.
But I thought high resolution was good! It is – especially on a computer with a high-end graphics card . But let’s take a look at what resolution does for you.
A VHS VCR (until recently, the most common type of mobile source unit) can send out images with 240 lines of horizontal resolution. Broadcast TV in the US tops out at 330 lines. While a DVD player can theoretically hit 1024 lines of output, most mobile players top out at 480. A Sony PS One (the most common in-car game system) starts at 224 horizontal lines, and can reach 480 with certain games. (The PS2 can hit 1024, depending on the game and settings). Since all car video products are using good old composite video (you know, the yellow RCA jack?), they can’t take advantage of the highest resolution settings on DVD. The high settings on a PS2 only work with the composite outputs, FYI.
High resolution is critical for one thing – in-dash navigation displays with “moving maps”. For anything else, it’s farther down the priority list, with the source units not pushing the envelope on resolution. You can have a monitor with 1160 lines of rez, but if your source unit is only peaking out at 224, you get no visual benefit from all those extra lines. Mobile video monitors are just starting to surpass 234 horizontal lines, and what many people think is the best-looking overhead monitor on the market has only 480 lines. There are other specs that end up making a greater impact in a car, specs that don’t affect your desktop monitor choices at all.
What’s more important? Well, brightness, for one, is more crucial in a car. All that outdoor ambient light can ruin your view. Contrast is important, too, but many say the most critical is viewing angle – how far to the side you can look at a panel without it “graying out” on you. Finally, response speed and temperature ratings go together. Finally, some non-LCD facts (stereo audio? Good input power and noise filtering? Good user interface? Solid bracketry?) are good to check on...
What’s a good brightness number? You need brightness (or “luminance”) of at least 300 cd/m2 (or “nits”) in order to have decent viewing with an overhead monitor, and you will need more than that in lower locations (like the dash or a headrest). There’s an overhead monitor out there (I won’t say which one), which is a cool size and great resolution, but only has brightness performance of 160 nits. Needless to say, it looks OK in the showroom, but awful in the car – or next to a competitor with 480 lines of resolution and a brightness rating of 420!
What’s a good viewing angle rating? The best you can get, basically – 100 degrees total horizontal or better (this may be stated as L + R seperately, or added together). Many video suppliers feel the need to put in swivels to allow the LCD panel to pivot to the L and R, due to their poor viewing angle performance. Unfortunately, the swivels are one more thing to break and rattle, and can be a weak point in the mechanics of your system. And when the monitor is being watched by two passengers, one on each side, what are they supposed to do – thumb wrestle over the monitor’s position? There is no substitute for viewing angle.
Why do I care about response speed and temp ratings? All LCD’s get slower in performance when they get cold, so you want as high a response time at ambient temperature, and as great a temperature rang as you can get, so that during the winter months your LCD performance doesn't degrade. It’s kind of like an amplifier that doesn’t shut off when it gets cold, but sounds awful – you wouldn’t want an audio system that sounded terrible every winter morning, so why have a monitor that looks blurry every winter morning? Times below 100 ms are essential. You want a temp rating of 0 to 60 Celsius. Unfortunately, these are often estimates, so look at response speed too (if you can)
LCD FAQ's
I want the highest resolution I can get, right? Well, if all other things were equal - but they aren’t. Shopping for a PC monitor and for mobile video are very different things.
But I thought high resolution was good! It is – especially on a computer with a high-end graphics card . But let’s take a look at what resolution does for you.
A VHS VCR (until recently, the most common type of mobile source unit) can send out images with 240 lines of horizontal resolution. Broadcast TV in the US tops out at 330 lines. While a DVD player can theoretically hit 1024 lines of output, most mobile players top out at 480. A Sony PS One (the most common in-car game system) starts at 224 horizontal lines, and can reach 480 with certain games. (The PS2 can hit 1024, depending on the game and settings). Since all car video products are using good old composite video (you know, the yellow RCA jack?), they can’t take advantage of the highest resolution settings on DVD. The high settings on a PS2 only work with the composite outputs, FYI.
High resolution is critical for one thing – in-dash navigation displays with “moving maps”. For anything else, it’s farther down the priority list, with the source units not pushing the envelope on resolution. You can have a monitor with 1160 lines of rez, but if your source unit is only peaking out at 224, you get no visual benefit from all those extra lines. Mobile video monitors are just starting to surpass 234 horizontal lines, and what many people think is the best-looking overhead monitor on the market has only 480 lines. There are other specs that end up making a greater impact in a car, specs that don’t affect your desktop monitor choices at all.
What’s more important? Well, brightness, for one, is more crucial in a car. All that outdoor ambient light can ruin your view. Contrast is important, too, but many say the most critical is viewing angle – how far to the side you can look at a panel without it “graying out” on you. Finally, response speed and temperature ratings go together. Finally, some non-LCD facts (stereo audio? Good input power and noise filtering? Good user interface? Solid bracketry?) are good to check on...
What’s a good brightness number? You need brightness (or “luminance”) of at least 300 cd/m2 (or “nits”) in order to have decent viewing with an overhead monitor, and you will need more than that in lower locations (like the dash or a headrest). There’s an overhead monitor out there (I won’t say which one), which is a cool size and great resolution, but only has brightness performance of 160 nits. Needless to say, it looks OK in the showroom, but awful in the car – or next to a competitor with 480 lines of resolution and a brightness rating of 420!
What’s a good viewing angle rating? The best you can get, basically – 100 degrees total horizontal or better (this may be stated as L + R seperately, or added together). Many video suppliers feel the need to put in swivels to allow the LCD panel to pivot to the L and R, due to their poor viewing angle performance. Unfortunately, the swivels are one more thing to break and rattle, and can be a weak point in the mechanics of your system. And when the monitor is being watched by two passengers, one on each side, what are they supposed to do – thumb wrestle over the monitor’s position? There is no substitute for viewing angle.
Why do I care about response speed and temp ratings? All LCD’s get slower in performance when they get cold, so you want as high a response time at ambient temperature, and as great a temperature rang as you can get, so that during the winter months your LCD performance doesn't degrade. It’s kind of like an amplifier that doesn’t shut off when it gets cold, but sounds awful – you wouldn’t want an audio system that sounded terrible every winter morning, so why have a monitor that looks blurry every winter morning? Times below 100 ms are essential. You want a temp rating of 0 to 60 Celsius. Unfortunately, these are often estimates, so look at response speed too (if you can)
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