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GeChic On-Lap 2501M 15.6" Battery-Powered Monitor, Tested
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1. GeChic On-Lap 2501M Portable Monitor

Here at Tom's Hardware, our desktops are complemented by large monitors (sometimes, several of them). Our notebooks tend to have nice high-res displays that let us get work done anywhere we go. But what about our tiny smartphones? We're accustomed to lots of space for productivity, and those four- and five-inch screens can be very straining on our eyes.

Yet, that's the direction mobility is increasingly going. These days, you can’t go to an airport without seeing hundreds of people glued to their smartphones or tablets. Although it's easy to get a bunch of entertainment onto a USB thumb drive, and convenient to burn time watching it on the road, wouldn't a larger screen help you actually enjoy it more?

GeChic looks to answer that question with its family of portable monitors, dubbed On-Lap. Thanks to a beefy internal battery, these thin, lightweight panels give you the larger size of a notebook-class screen, sans the unwieldy wall plug.

GeChic sent us its newest model, the 2501M. Offering a resolution of 1366x768 pixels, it’s just the thing for road warriors who want something larger than a tablet or smartphone to watch videos or browse photos when they’re away from home. You can hook up a myriad of different sources to the On-Lap, and view any kind of content a computer or phone can output. We're putting the On-Lap through our benchmark suite so that you know what to expect from a mobile monitor.

The On-Lap 2501M bridges the convenience gap between a tablet and a laptop. It’s lightweight at just over two pounds, and around half of an inch thick. Inputs and controls are on the upper-right side, so they’re easy to reach when the monitor is in use. A protective cover snaps on to keep the screen from getting damaged, then doubles as a hinged base that works equally well in your lap or on a flat surface.

In the screen's box, you'll find a small clip that can be used to attach a smartphone to the front of the panel. The fit is going to be secure, but you're pretty much limited to an iPhone or similarly-sized handset held in the landscape position. Anything significantly thicker or smaller won't stay attached reliably. Unfortunately, any device you use with the clip also blocks the lower-right corner of the monitor, too.

                                   GeChic On-Lap 2501M Technical Specifications                                  
Panel Type
Twisted Nematic (TN)
Backlight
LED
Screen Size
15.55"
Max Resolution
1366x768
Aspect Ratio
16:9
Response Time (GTG)
8 ms
Brightness (cd/m^2)
200
Speakers
2 x 1 W
VGA
1
HDMI
2 (1 MHL)
Refresh Rate
60 Hz
Battery Life
Six hours
Dimensions (W x H x T)
15.7 x 10.3 x 0.6 inches
395 x 260 x 16.3 mm
Weight
2.89 lbs
Warranty
1 year
Price
$270


A large variety of devices can be connected to the 2501M: the On-Lap can extend the display of a computer, tablet, smartphone, camera, gaming system, or DVD/Blu-ray player. Thankfully, GeChic includes a full complement of cables for the On-Lap’s three video inputs, a practice we'd like to see more companies follow. HDMI is supported via a mini connector, while block adaptors for traditional HDMI cables and jacks are in the kit as well. Since HDMI carries audio too, GeChic integrates speakers and headphone output into the On-Lap.

If you have an MHL-compatible device, the On-Lap supports it directly. MHL, or Mobile High-Definition Link, is a relatively new standard that allows transmission of up to 1080p/60 Hz video and 7.1-channel surround sound, while simultaneously charging the connected device. This interface is showing up on more and more phones, tablets, and other portable devices.

Battery life is obviously dependent on how you use the On-Lap. The rated capacity is 9300 mAh from the internal lithium-ion cell. With the brightness maxed and the audio volume on 10, GeChic quotes six hours typical usage time. Of course, an AC adaptor is included so you can plug-in to charge the battery or simply power the monitor.

2. Measurement And Calibration Methodology

To measure and calibrate monitors, we use an i1Pro spectrophotometer and the latest version of SpectraCal CalMAN software (v5.0.3).

For patterns, we employ an AccuPel DVG-5000 video signal generator. This approach removes video cards and drivers from the signal chain, allowing the display to receive true reference patterns. Connections are made via HDMI.

The AccuPel DVG-5000 is capable of generating all types of video signals at any resolution and refresh rate up to 1920x1080 at 60 Hz. It can also display motion patterns to evaluate a monitor's video processing capabilities, with 3D patterns available in every format. This allows us to measure color and grayscale performance, crosstalk, and ghosting in 3D content via the 3D glasses.

We realize that the On-Lap 2501M will not be calibrated by its typical user. This is, after all, a convenience product, not a performance-oriented one. Still, we feel it’s relevant to run any display through our battery of tests so that you know what image quality to expect. Except for gamma control, the On-Lap has the same calibration adjustments available on a desktop monitor. There are no picture modes, so you can’t toggle between different settings combos. The table below holds the settings that we used in our tests.

Contrast
50
Brightness
100
Red
55
Green
53
Blue
52
Color Temp
User
3. Results: Stock Brightness And Contrast

Since the On-Lap 2501M is a twisted-nematic (TN) panel, we’re using some comparison data from past reviews of 23- and 24-inch TN-based panels. We're also including data from the last four screens we tested, all of which are 27-inch IPS monitors.

With its brightness control set to maximum, the On-Lap comes up a tick shy of the 200 nit mark. For a monitor that will likely be used in bright environments, we would like to see a little more light output.

The max black level falls just below the middle of our pack. However, 0.4625 cd/m2 isn’t a bad result. In fact, in a high-ambient light environment, this will serve to keep shadow detail visible.

Contrast ratio is the most important factor concerning the perceived depth and dimensionality of the image. The greater the ratio, or dynamic range, the more three-dimensional the picture will appear.

The max contrast ratio is toward the bottom of the pack; a little more light output would help improve this number.

Turning down the brightness control all the way generates some very low numbers for both maximum white and minimum black.

At just over 17 cd/m2, the image is far too dim to be of any use, even in a blacked-out environment. We recommend setting the brightness to no lower than 25. At that level, the white luminance increases to around 45 cd/m2.

On the plus side, bottoming out the brightness slider produces a very impressive black level. Thanks to the On-Lap’s excellent gamma tracking, shadow detail is maintained even at this low reading.

Again, minimizing the brightness produces an image that is not practical for normal use. With the brightness control on 25, the black level is still less than 0.1 cd/m2, which puts it in fourth place.

The minimum stock contrast ratio is pretty much unaffected by the position of the brightness slider. No matter where it’s set, the ratio lands between 420: and 430:1.

Contrast performance is not a strong suit of any LCD panel, regardless of the technology it employs. While this metric has improved over the last few years, it’s still behind other display technologies, such as plasma. And alas, the tremendous dynamic range of our dearly departed CRT monitors may not be equaled until OLED panels become more viable.

4. Results: Calibrated Brightness And Contrast

Since we consider 200 nits to be an ideal average for peak output, we calibrate all of our test monitors to that value. In a room with some ambient light (like an office), this brightness level provides a sharp, punchy image with maximum detail and minimum eye fatigue. It's also the typical sweet spot for gamma and grayscale tracking, which we'll look at over the next two pages.

While calibrating the On-Lap 2501M improves the grayscale measurements, which you’ll see later, it also slightly reduces the maximum white and contrast ratio. You’ll have to decide whether perfect white balance or maximum contrast is more important to you.

A drop in peak output after calibration is not unusual for any display. In this case it was only a seven-percent reduction. While the On-Lap can't  quite get to 200 cd/m2, it only misses the mark by nine percent.

The black level rises substantially to over 0.5 cd/m2. Again this is not uncommon for any calibrated monitor.

The On-Lap finishes right in the middle of our pack for calibrated black level performance. It's only bested by one TN monitor, though. If you remove the IPS competition, the On-Lap does quite well.

Calibration reduces the contrast ratio by 19 percent versus the stock configuration. Again, you’ll have to decide if the compromise in grayscale performance is worth giving up some dynamic range.

When comparing the On-Lap to other TN-based monitors, it does fairly well; it's only beaten by the Dell. However, it lags well behind the IPS panels we’ve tested.

5. Results: Gamma And ANSI Contrast Ratio

Gamma

Gamma is the measurement of luminance levels at every step in the brightness range from 0 to 100 percent. This is important because a poor gamma can either crush detail at various points, or wash it out, making the entire picture appear flat and dull. Correct gamma produces a more three-dimensional image, with greater depth and pop. Meanwhile, incorrect gamma can negatively affect image quality even in monitors with high contrast ratios.

We’re now including the gamma tracking charts for all the monitors we test. The yellow line represents 2.2. The closer the white measurement trace comes to 2.2, the better.

The On-Lap does fairly well in this test. The values drop slightly as the signal level approaches 90 percent. A lower gamma value means the image is too bright at that luminance point. The measurement at 90 percent is around 1.8, which equates to four percent too high.

Turning to the comparison charts, the On-Lap performs adequately versus its competition. We don’t have gamma data for any of the TN-based panels from past reviews, so we only included the IPS monitors in these charts.

Bear in mind that the four IPS panels in this comparison boast superb gamma performance, and the On-Lap is only slightly behind the group.

The gamma value range tells us how close each signal level from zero to 100 percent comes to the 2.2 standard.

This is a very good result. The lower numbers indicate flatter gamma tracking. This means the display will closely match the mastering specification of the original content, so you’ll see maximum detail no matter what the brightness level is set to.

ANSI Contrast Ratio

Another important measure of contrast is ANSI. This is a relatively new benchmark for our monitor reviews. To perform this test, a checkerboard pattern of sixteen 0 and 100 percent squares are measured. This is somewhat more real-world than on/off measurements because it tests a display’s ability to simultaneously maintain both low black and full white levels. This test also factors in screen uniformity. The average of the eight full-white measurements is divided by the average of the eight full-black measurements to arrive at the ANSI result.

It’s not surprising that the On-Lap doesn’t do particularly well. After all, the on/off contrast is only fair. On the plus side, its ANSI contrast ratio is slightly higher than its on/off ratio, meaning that contrast will be maintained no matter what image is being displayed.

6. Results: Grayscale Tracking

For a product like the On-Lap 2501M, stock grayscale performance is very important since it’s unlikely that a user would calibrate this display. It is important that the color of white be consistently neutral at all light levels from darkest to brightest. Grayscale performance impacts color accuracy with regard to the secondary colors; cyan, magenta, and yellow. Since computer monitors typically have no color or tint adjustment, accurate grayscale is key.

The stock measurement shows a slightly cool result. Fortunately, green and blue track together, so the overall tint to white is barely noticeable. This is affirmed by the Delta-E numbers, which just barely exceed the visible level from 30 to 80 percent. The best stock setting for color temp is the 6500 K preset.

Adjusting the RGB sliders and increasing the brightness to maximum produces the following result. You can see Delta-E values are now all below three.

Green and blue track fairly well, but red starts to rise as the signal level increases. Turning up the red slider any higher produces a visible tint to the brightest whites, which is simply unacceptable for a computer monitor.

Compared to more expensive IPS monitors, the On-Lap does pretty well.

With an average stock Delta-E error of only 3.54, you are unlikely to notice any tint to the white balance. This is very good performance.

Calibrating the On-Lap only reduces the error by 1.34 Delta-E. You're going to notice the difference in lost contrast much more than the difference in white balance.

As mentioned, calibrating the On-Lap reduces its contrast performance by around 19 percent, which is enough to be visible to the naked eye. Since dynamic range is still the ultimate metric for image quality, we recommend leaving the panel in its stock configuration and adjusting the brightness to taste. Dialing in the white balance won’t make an appreciable difference, and the reduction in contrast just isn’t worth it.

7. Results: Color Gamut And Performance

Color gamut is measured using a saturation sweep that samples the six main colors (red, green, blue, cyan, magenta, and yellow) at five saturation levels (20, 40, 60, 80, and 100%). This provides a more realistic view of color accuracy. The On-Lap has no color management system, so the chart is the same before and after calibration. Additionally, adjustments made to grayscale are too small to have any effect on the secondary color points.

This is the only area where we feel the On-Lap 2501M comes up short. Its color gamut is quite a bit smaller than the sRGB/Rec 709 standard.

Take a look at the dots furthest from the center of the CIE chart. They should be at or near the outermost squares, which represent the correct color points. It seems that only cyan is close to accurate. The other colors never quite reach the full saturation point. The visible effect is that the color looks somewhat washed out and light. This is made up for a little bit by the increased luminance, which you can see in the middle chart. Red, blue, and magenta are brighter than they should be, but this gives an illusion of extra saturation. And the Delta-E chart shows these errors are visible to the naked eye.

When a display measures this far off the standard, we do a test called Actual Secondaries. The monitor’s actual measured primaries are used to calculate where the secondary colors (cyan, magenta, and yellow) should be.

We can tell that the On-Lap is the product of some clever engineering because its secondaries fall exactly where they should in the altered gamut. Given this fact, combined with the increased luminance values, the color on this display actually looks OK. It’s a little washed-out, but not nearly as much as these charts suggest.

All of our recently-tested screens come much closer to the sRGB/Rec 709 standard.

The average value doesn’t tell the whole story of the On-Lap. The Delta-E error for blue is over 10, but the extremely low error for cyan pulls the average number down somewhat.

Gamut Volume: Adobe RGB 1998

There are basically two categories of displays in use today: those that conform to the sRGB standard like HDTVs, and wide-gamut panels that show as much as 100 percent of the AdobeRGB 1998 spec. The On-Lap displays less than half the latter gamut. In fact, it only displays 55 percent of the sRGB gamut, which is a good deal behind other TN-based monitors.

We use Gamutvision to calculate the gamut volume, based on an ICC profile created from actual measurements. With only 39 percent of the AdobeRGB 1998 gamut available from the On-Lap, you won’t want to use this product for critical graphics work. Its color output would be difficult to match to other devices like cameras and printers. For gaming, video, and business use, though, it should be fine. Even though the color is under-saturated, the On-Lap is accurate relative to its actual color measurements.

8. Results: Viewing Angle And Uniformity

The On-Lap 2501M is a TN panel, so its off-axis performance isn’t quite at the level of the IPS panels we’ve had in the lab recently. To better show the degradation of image quality, we’re now photographing grayscale step patterns. This way, it’s easier to see how all brightness levels are affected as you move off-center.

The On-Lap is pretty much a one-person display. If you want to share the image with another person, they need to sit close. Three people would probably not enjoy the picture as much. The side and bottom angles are especially dim at 45 degrees. The top angle doesn’t lose as much brightness, but you can barely see the steps in the pattern. The advantage to this is you can maintain privacy when working in a public space, such as an airport.

While some monitors are better than others, no LCD panel has perfect screen uniformity, and even samples of the same model can have quite a bit of variation. So, since there’s no solid standard for applying a rating to different monitors, we’ll simply present the results of our measurements.

To measure screen uniformity, zero percent and 100 percent full-field patterns are used, and nine points are sampled. We’re now expressing the values as percentages relative to the center of the screen.

GeChic On-Lap 2501M
Black Field Uniformity (percentage of center)
101.90%
88.58%
94.16%
100.86%
100.00%
91.89%
94.11%
83.21%
88.81%
White Field Uniformity (percentage of center)
102.17%
94.75%
100.06%
96.42%
100.00%
90.48%
94.83%
91.25%
89.53%


The On-Lap does fairly well in this test. We are especially impressed by its black field uniformity. While it’s not quite as impressive as the Samsung S27B970D, it is better than most of the other monitors we’ve tested. While the smaller size does help, again, some excellent engineering is obviously at work here.

9. Results: Pixel Response And Input Lag

Pixel Response And Input Lag

To perform these tests, we use a high-speed camera that shoots at 1,000 frames per second. Analyzing the video frame-by-frame allows us to observe the exact time it takes to go from a zero-percent signal to a 100% white field.

The pattern generator is placed at the base of the monitor so that our camera can capture the precise moment its front-panel LED lights up, indicating that a video signal is being received. With this camera placement, we can easily see how long it takes to fully display a pattern after pressing the button on the generator’s remote. This testing methodology allows for accurate and repeatable results when comparing panels.

We’ve returned the data from our past TN-based monitor reviews to the charts so that comparisons can be made between IPS and TN technology.

The On-Lap is slower than other TN monitors in the response time test. It’s also takes a hair longer to draw a full-white screen than the 27-inch IPS panels we’ve recently tested. Let’s see how the overall input lag affects the numbers.

The On-Lap is still at the back of the pack for absolute input lag. This is not a screen for hair-trigger gamers with Jedi-like reflexes. It’s certainly fine for slower-paced mainstream games, though. With two HDMI inputs, you can hook up a laptop or even a console to it for a truly portable gaming experience.

10. Battery Life And Conclusion

Battery Life

To test the battery life, we’re using the same parameters as GeChic’s spec sheet. The brightness is turned up to maximum and the speaker volume is set to 10. Content is fed via HDMI from a standard Blu-ray player, allowing us to simply loop a movie until the battery is completely drained. The panel is fully charged, of course, and the test starts promptly after we unplug the charger.

The On-Lap 2501M manages to handily exceed GeChic's specification in our testing. At seven hours and twelve minutes, the low-battery indicator came on and we called it quits. At this stage, the On-Lap automatically lowers its brightness and audio volume to stretch the battery as long as possible. Since this is more than an hour longer than we were expecting, we're satisfied with the result. You can extend the battery by not using the speakers at all, or by turning down the brightness.

An Interesting Product, In The Right Context

The On-Lap 2501M is a unique product. While it doesn’t knock our socks off in terms of performance, there really isn’t anything else like it out there. What the On-Lap has going for it is excellent battery life and a thin, lightweight form factor. You can easily carry the thing with you in a laptop bag or backpack. And, with a full set of cables included, it can be used with a wide variety of sources right out-of-the-box. The On-Lap is one of those products that you buy for one reason, but then discover a half-dozen other uses for it.

Then again, for $270, it might make more sense to consider a few other portable products, such as a $250 Chromebook. And there’s no escaping the fact that desktop monitors of this size sell for less than $150. Plus, you'll need to decide whether tethering a smartphone or tablet to another device is even practical when integrated solutions exist.

That's not to say this product is without merit; it's just marketed all wrong. Since the On-Lap lacks a touchscreen, you aren't actually turning your smartphone into a large tablet. You still need control everything from your source device. And seeing as how GeChic prices the 2501M higher than some of last year's most popular 7" tablets sell for, it's simply a hard sell in the consumer space.

Busy professionals, on the other hand, can justifiably benefit from this product. Let's say you're a road warrior, and you want to fully utilize that desk in your hotel room. Using the On-Lap, you can add a second 15.6" screen to your laptop's display and create a mobile multi-monitor configuration. After all, the On-Lap is certainly more portable than any desktop monitor. This could have come in handy for those of us who stayed up late writing CES coverage this year in our hotel rooms, flipping between Word, Excel, Outlook, Skype, and Firefox. Additionally, a wide variety of ports and an integrated battery pack make the On-Lap an extremely portable display for mobile PC techs troubleshooting no-video issues.

So, in the right situations, GeChic's On-Lap can be a useful complement to your mobile arsenal. But at $270, it's hardly a gadget accessory.