PRODUCT REVIEW
Sharp PN-455 LCD Monitor
Sharp’s 45-inch LCD monitor is a “do-it-all” design for digital signage that combines simplicity and performance in a neat package — along with a couple of quirks.
We’ve come a long way in the past decade with regard to LCD monitor technology. It wasn’t that long ago that Sharp was pushing the envelope with a costly 28-inch product (nearly $15,000) and could only achieve sizes of 40 inches and larger by tiling (stitching) smaller panels together.
Today, 40-inch, 42-inch, 45-inch, and 46-inch LCD panels are no big deal to manufacture, nor are they particularly expensive. Those are two big reasons for the boom in digital signage, not to mention skyrocketing sales of consumer flat-panel television sets.
The PN-455 monitor uses the same LCD panels as Sharp’s Aquos TVs, but doesn’t have all of the bells and whistles. Instead, it provides a few of the most common connectors and moderate functionality. More importantly, it has 1920x1080 pixels of native resolution, which is critical for digital sign applications that show maps and fine text.
Figure 1. Sharp’s PN-455 1920x1080 LCD monitor
OUT OF THE BOX
The design of the PN-455 can best be described as “stealth.” It has a matte black frame around a black bezel, surrounding the screen. It can be wall-mounted or flown; I chose to install two simple, U-shaped “temporary” metal feet to support the monitor. Only a small Sharp logo and a yellow/green power indicator are seen on the front panel.
The rear panel provides a few video interfaces, but some of them are baffling. For mainstream analog component interfaces, there’s a 15-pin VGA jack that loops through to another 15-pin jack (in case you want to daisy-chain a few PN-455s). There’s also a DVI-D connector nearby. To the right of that, you’ll find a composite video RCA jack and a DIN S-video jack.
All well and good, except there’s another composite video jack on this panel that uses a BNC connector, way over to the left. To get it to work, you must run an RCA-to-RCA jumper from a second RCA jack (positioned next to that BNC jack) to the RCA composite video jack on the right of the rear panel.
It gets weirder. To the right of the DVI jack is a small D4 connector, which is where a component (YPbPr) signal would be connected. Don’t have a D4 plug? You can get breakout cables easily enough, according to Sharp. Or, you can connect the supplied D4 jumper cable to another D4 jack on the lower right panel, which then lets you use three BNC jacks for a component video connection.
(This got me to wondering: Why didn’t Sharp just provide a dual BNC/RCA composite jack, along with 5 BNC jacks that could function as both an RGB and YPbPr interface, and do away with the need for composite video and D4 jumpers?)
For control purposes, there is an RS-232C input connector and an output connector. There are two audio input jacks (both stereo), and stereo RCA jacks for audio output. The internal 10W stereo amplifiers drive a pair of push-type speaker terminals.
REMOTE AND MENUS
The supplied remote is so small; I almost overlooked it in the packaging. It is the epitome of simplicity, sporting just 11 buttons, including serial input selection (direct selection is always better), multiple screen sizes and image zoom settings (Normal, Dot-by-Dot, Wide, Zoom 1, and Zoom 2), and brightness modes (Standard, Office, and Vivid).
I didn’t find the remote responsive at times, even when it was held close to the front IR sensor. It sometimes took several button pushes to get to a menu or change an input. I’m not sure why; the remote had fresh batteries in it.
The menus are somewhat primitive in appearance and use simple colored text on a black background. That’s quite a step down from the elegant Aquos menus! With video signals, you’ll have access to the usual “big 5” adjustments (brightness, contrast, color saturation, hue, and sharpness), plus five white balance presents — Cool, Standard, and Warm, with two in-between steps.
With analog RGB signals, you’ll have access to clock, phase, and H&V adjustments, plus brightness, contrast, and RGB drive tweaks for custom white balance. However, the User setting for custom white balance in RGB mode is not accessible when displaying composite, S-video, or component video signals.
Sharp isn’t the only manufacturer that locks out RGB drive/gain settings for video signals — I’ve seen this set-up plenty of times in projectors, plasma monitors, and other LCD displays. I can understand the reason for limiting consumer access to these controls, but why anyone would do this with an industrial monitor is a complete mystery to me. What if someone wanted to set up a wall of monitors and show HD video clips that required closer white balance calibration to suit a client’s needs?
ON THE TEST BENCH
LCD monitors are becoming the preferred displays for many digital signage applications because they are plenty bright and have nits to spare. The PN-455 doesn’t disappoint in that regard. After calibrating the review unit for best grayscale images, I measured 314 nits with a full white screen in Standard mode. Switching to Office mode dropped that reading about 30%, but Vivid only raised it by a meager 1%.
Although LCD monitors can crank out the photons, their black levels are much higher than those of comparably sized plasma monitors. I measured average black levels of 1.53 nits, which is good for an LCD monitor (and Sharp usually leads in this area) but about eight times higher in luminance when compared to a pair of 50-inch plasma TVs I happened to be testing at the same time.
This resulted in contrast readings of 217:1 average and 234:1 peak, not shabby for an electronic display, but nowhere in the league of the 400:1 to 600:1 readings I routinely get from plasma displays these days. (In defense of LCD technology, none of those plasma displays can approach full screen white readings of 100 nits — otherwise, they’d burn out pretty darn quickly.)
Figure 2. LCD color is good, but the CCFL backlight falls short of the REC-709 gamut
Figure 3. The PN-455 tracks grayscales better at lower color temperatures
Another area where LCD technology often comes up short to phosphor-based displays is in colorimetry. Using a Datacolor ColorFacts 6.0 analyzer, I plotted the actual color space of the PN-455 and compared it to the REC-709 color space. The PN-455 covers about 70% of the 709 space; coming up somewhat short with red, more so with blue, and quite a bit short in the green channel. Oddly, the cyan and magenta coordinates were almost dead on.
Although you can set the white balance more precisely with RGB signals, I opted to plot grayscale tracks for the PN-455’s Standard and Warm picture modes, using the component video input. Figure 3 shows both tracks, with the Standard grayscale starting very cold at just under 10000 degrees and drifting over 300 degrees downward. In Warm mode, the grayscale performance is much better with a total shift of 1337 degrees from 6749K @ 20 IRE to 5412K @ 100 IRE — not great, but tolerable.
SIGNAL COMPATIBILITY AND IMAGE QUALITY
Despite the PN-455’s input connector and operation quirks, it proved to be quite versatile with a variety of signal formats. Sharp projectors spoiled me for years with their ability to latch on to and sync up with almost any PC and video signal format, and the PN-455 is good to go as high as 1280x1024 @ 64 kHz with standard 4:3 or 5:4 display drivers, and also accepts several widescreen formats including 1280x720, 1280x768, 1360x768, 1366x768, and 1920x1080 (all progressive RGB).
The component video input isn’t quite as versatile, but will happily accept 480i, 720p, and 1080i signals. You can also go digital through the DVI port, as it accepted not only PC rates but also showed 480p, 720p, and 1080p/24 segmented frame test patterns. More importantly, the PN-455 has plenty of signal bandwidth and was able to reproduce luminance multiburst patterns out to 37.5 MHz in 720p and 1080i modes on all inputs. You’d be surprised how many consumer HDTV displays flunk this test!
As expected, static RGB image quality is excellent with plenty of detail to be seen. The panel scales RGB signals to its available resolution quite well, and even provides options for scaling default resolutions in the menu. There is an AUTO set-up mode for every input and it works exceptionally well in setting pixel clock and phase.
Video is a different beast altogether. Composite video decoding is excellent at a time when other manufacturers have lost interest in supporting the format. I saw lots of detail at 300 and 400 lines with a Zone Plate test pattern. 3:2-mode detection is also quick and reliable, as shown by the racecar sequence on the Realta HQV test DVD.
However, you’ll see plenty of scan line artifacts in all interlaced video modes, even with smooth motion. I strongly suggest feeding this display a steady diet of progressive-scan video. Given that the RGB input will support 1080p/60, you could also employ an outboard scaler to process 1080i (which doesn’t look as bad as 480i) from component YPbPr and feed it to the display.
You will see some smear with fast-motion video, something that all LCD manufacturers continue to work on. It won’t be as noticeable with content that originated as film or with film refresh rates (like 1080p/24). But it’s definitely there with fast-motion live video, such as basketball, football, hockey, and auto racing.
In terms of power consumption, I measured an average of 284.2 watts over a six-hour period, using video from a 24-hour news channel. Total power consumption was 1.726 kWh. Assuming a base rate of $0.08/kWh for electricity, it cost 13.8 cents to operate the PN-455 for six hours.
The PN-455 has an active power conservation circuit. If a valid signal isn’t detected on a given input within a few seconds, the monitor automatically powers down. Once the signal is restored, the monitor automatically turns itself on. That’s a handy feature for timed, unattended operation and environmentally smart.
CONCLUSION
Sharp’s PN-455 would make an excellent choice for any digital display. It can handle a wide range of PC and video signal formats, has just enough connectors to be practical (notwithstanding those crazy jumpers), and is pretty much even with the state of the art in LCD contrast, brightness, and color when using cold-cathode fluorescent lamps.
Shortcomings: I’d like to see those input jumpers eliminated and access to white balance controls provided for every input, not just RGB and DVI. The OSD, while practical, just looks so early-1990s, and the remote wasn’t one of my favorites — direct input access would be a plus.
