Screen Quality

Since we're talking about a 14" monitor being powered entirely off of a pair of USB 2.0 ports, producing a quality image is actually a fairly low priority. Toshiba's Mobile Monitor uses a 14" TN panel, but thankfully eschews the glossy finish that GeChic opted for on their screens. Still, picture quality is pretty dire: the screen is less than ideal for video and certainly inadequate for any kind of serious, color-sensitive image editing work.

Toshiba rates the Mobile Monitor at a brightness of 220 nits and a contrast ratio of 400:1, which is almost comically exaggerated (just like GeChic's ratings were). Here's how the Mobile Monitor stacks up compared to the two GeChic screens:

  White Level Black Level Contrast Delta-E Color Gamut
Toshiba Mobile Monitor 129 0.74 174 13.64 50.3
GeChic OnLap 1301 142 0.7 134 2.53 42.7
GeChic OnLap 1302 186 1.19 156 2.53 42.7

At least partially due to the smaller screen size but also undoubtedly also due to not having to power a DisplayLink chip, GeChic's screens are able to produce better brightness than Toshiba's can. While Toshiba's screen also demonstrates a slightly better percentage of the AdobeRGB1998 gamut, it's not exactly a major win either, and the delta-e is absolutely horrendous--almost like our calibration software just doesn't work with the USB-based display, which is entirely possible. Honestly it's fairly easy to notice the Toshiba screen just isn't producing super accurate color, but given what it's intended for, this is something we can live with.

It's also worth mentioning that while the Toshiba Mobile Monitor has a brightness control, there are only two settings, making me wonder why they bothered with two brightness buttons. The figures I listed above are at full brightness; the low brightness setting is half the white level and black level.

Performance

Here's where things get a bit dicey and where the difference between a display driven by DisplayLink and a display driven by a proper GPU surfaces. First, let's take a look at a basic metric: power consumption. Since these screens are all being driven off of the notebook's power, we can hook our test system, Acer's Aspire TimelineU, up to our Kill-A-Watt meter while plugged in and get a basic idea of how much power they pull.

  Power (in Watts)
No USB Display 9
Toshiba Mobile Monitor, Idle 15.5
Toshiba Mobile Monitor, Load 29.3
GeChic OnLap 1301, Idle 14.6
GeChic OnLap 1301, Load 20
GeChic OnLap 1302, Idle 15.6
GeChic OnLap 1302, Load 25.5

I connected each monitor (one at a time), set it to clone, and then dragged a Gamutvision screen around the desktop to give it some work to do. The increased brightness of the OnLap 1302 seems to take its toll on power consumption, but DisplayLink's CPU overhead is an even bigger hit. In fact, during testing, while the GeChic displays worked fine, the bottom half of the Toshiba Mobile Monitor actually cut out completely. The complete image came back after a reboot, but this is worth noting nonetheless.

In more casual use, the Mobile Monitor held up a lot better. It was able to play back 720p YouTube video with relative ease, and it's certainly fine for any basic desktop tasks. I also like the form factor of Toshiba's solution a lot more; while GeChic's displays both use clunky mounting mechanisms to attach to a notebook or flimsy stands made out of green rubber blocks, Toshiba's screen comes built into a nice leather folio that folds open into a stand. True, it's not physically attached to the notebook like GeChic's displays are, but I honestly prefer having a better stand.

The quirks of the Mobile Monitor stem more from the DisplayLink technology than anything within Toshiba's power. When testing video I was able to detect a slight lag between video and sound (nothing major), and the system has a hard time resuming from sleep mode with the Mobile Monitor attached. The Mobile Monitor will produce a picture while the main system display won't. None of these quirks manifest while using GeChic's solutions, but that's because GeChic's solutions are essentially basic screens that happen to use a USB cable for power instead of a standard power cable.

Introducing Toshiba's 14" USB Mobile LCD Monitor Conclusion: Depending on Your Needs
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  • repoman27 - Wednesday, June 27, 2012 - link

    Stupid phone, that was meant to be in response to the next comment. Reply
  • lead_org - Wednesday, June 27, 2012 - link

    Okay so that power consumption figure would be different, if you used a different laptop with different CPU/GPU package.

    So you only tested this monitor on a X100e/120e ThinkPad?

    Also, with my ThinkVision LT1421, i can power the entire monitor off a single USB port from the laptop. Can this Toshiba unit do the same?
    Reply
  • lead_org - Wednesday, June 27, 2012 - link

    How did you arrive with the power consumption figures?

    what you stated sounded a bit high.
    Reply
  • themossie - Wednesday, June 27, 2012 - link

    Agreed.

    For the Toshiba under load: 29.3 watts at 5 volts?
    It's pulling ~6 amps between 2 USB ports?
    Which computer (or common charger, even) lets you pull 3 amps/USB port?

    Even the 20 watts for the GeChic 1301 OnLap is pushing it (would require the laptop to support 2 amps each on 2 USB ports), let alone the 1302...

    Something's very wrong here, Dustin.
    Reply
  • silverblue - Wednesday, June 27, 2012 - link

    I'm not sure if this has any bearing on things...

    Added to the USB 2.0 and 3.0 specs in December 2010:

    Battery Charging Specification 1.2[12]: Released in December 2010.
    Several changes and increasing limits including allowing 1.5A on charging ports for unconfigured devices, allowing High Speed communication while having a current up to 1.5A and allowing a maximum current of 5A.

    However, from a product review of this screen on the Toshiba website, it states you cannot use maximum brightness without the (optional) AC adaptor. Is this true?
    Reply
  • themossie - Wednesday, June 27, 2012 - link

    Good catch. I've seen this standard, but not seen it (completely) implemented.
    3 amps is the max I've seen, and that one doesn't use any real standard... just shorts the data pins and calls it a day.

    Can anyone link me to a 5 amp USB charger? Or a desktop/laptop which puts out more than 2 amps/port?
    Reply
  • Death666Angel - Wednesday, June 27, 2012 - link

    It uses that much power from the wall, not the additional display itself.
    Considering the gap between no USB display and idle USB display, I think it's safe to assume the additional USB display added 6W to the power consumption (increased load being more due to heavier CPU load due to the display branching off the CPU and not the GPU). So your whole 30 Watts at 5V is nonsense. :-)
    Reply
  • themossie - Wednesday, June 27, 2012 - link

    Completely my bad. I both misread the preceding paragraph and missed the "9 watts with NO USB DISPLAY". All I can offer in defence is that I'm not the only one to do so...

    Back to power - the monitor + extra system load draws an extra 21 watts at the wall, call it 18 watts (~75% efficiency PSU). Subtract 6-10 watts for the monitor, leaving 8-12 watts for increased system load in a test bed with (assuming i7-2637m) a 17 watt TDP CPU?

    I'd like to see CPU load figures while this is running, that's a pretty hefty hit. It's still 3 times the power consumption of a single monitor, which would be pretty detrimental to mobile computing.

    Again I suggest my solution posted a few posts down - which is cheaper, lighter, won't load the CPU or run off of the laptop battery and doesn't need questionable drivers (HDMI input) at the cost of 2.5" less screen size.
    Reply
  • Dustin Sklavos - Thursday, June 28, 2012 - link

    CPU load runs between 10% and 40% on the 17W i7. Reply
  • lead_org - Wednesday, June 27, 2012 - link

    You do know how much power a standard USB 2.0 can put out right?

    For comparison purpose a Lenovo ThinkVision LT1421 can draw a maximum of 5 watts under full load.

    http://support.lenovo.com/en_US/product-and-parts/...
    Reply

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