27th January 2011, 2:16 AM
Quote:Umezu: What eats more electricity than anything in a handheld gaming device is the LCD backlight.From http://iwataasks.nintendo.com/interview....s-made/1/0
Iwata: Nintendo 3DS has two of those—and the upper one is for 3D.
Umezu: Right. And the 3D one has to delivery separate images to the left and right eyes. Which means that in 3D the amount of light delivered to each eye is halved. In order to make it look just as bright as usual, you have to increase the brightness of the backlight, which increases the power used by even more.
Iwata: Choosing 3D led to the need to double the graphics and increase the brightness of the backlight, so there must have been a lot of challenges with regard to power.
Umezu: I knew from the very start that the LCDs would require lots of power, so I thought we couldn't use that much for graphics. I spent quite a lot of time looking into programmable shading, but when you use that method for a handheld game system, you also have software processing in the SoC, and a number of steps become necessary for calculating the shading to render one point on the screen, so it can't keep up if the operating frequency21 isn't fast enough.
Iwata: In other words, that method eats up too much power.
Umezu: Yes. We knew that DMP's technology had the merit of calculating with the hardware, so we could cut down on the power used. 21. Operating frequency: Also known as clock rate. It signifies the rate for synchronizing the parts of a circuit.
Iwata:
DMP's technology achieves with the hardware most of the shadow calculation usually done by a programmable shader, so even a slower operating frequency can achieve the same results. With today's semiconductor technology, the frequency has a direct influence on power use, so it's very beneficial in that regard.
Umezu:
Yes. I thought DMP's technology was best for saving power, given the limits of a handheld gaming system. What's more, to save power just a little more, we prepared a power save mode for the backlight.
Umezu: As mentioned earlier, what uses the most power in a handheld gaming device is the LCD backlight, and making one screen 3D presented the problem of even more power used by the backlight. The power save mode uses a technology called active backlight. It precisely controls the brightness of the backlight according to the brightness of the screen being displayed. When the screen as a whole is dark, the backlight itself gets darker, which saves power.
Iwata: In principle, it may not be much use in a game with lots of bright screens, but if you set the backlight to bright, the more darker screens there are in a game, the greater the effect of the power save mode.
Umezu: Right. But you can't say exactly how much of an effect the power save mode is having on game processing because of the various factors that influence power use, such as how constantly the SoC is running, whether you're using the camera or wireless, and how loud the volume is set.
Iwata: Maybe you can't be exact, but how about an approximation?
Umezu: We announced the other day that the battery duration for playing Nintendo 3DS games on it is about three to five hours. When I measured it by playing several Nintendo games, with the backlight set to the brightest level and the power save mode turned off, battery duration was about three hours. But if you use the power save mode under the same conditions, it gets about 10-20% longer. And if you set the backlight to the darkest setting, the battery lasts five hours, but the power save mode makes less of a difference then.
Iwata: In other words, the brightness of the backlight has the greatest effect on battery duration.
Umezu: Right. What's more, with the backlight set as high as it will go, battery life changes about 25% according to whether you're playing in 2D or 3D.
Iwata: Yes, 3D is a battle against power use. How about wireless use? Some players may be worried about that.
Umezu: In StreetPass mode, the system isn't always communicating, so there isn't much of a drain on the battery, but games that communicate a lot through local play and online play—with the backlight set to high—have an over 10% effect on the battery.
Iwata: So it will be necessary for this system to be charged more often than for the previous systems. For that reason, we include a special charging cradle. We recommend that when players get home, they put their system there.
Estimate from GAF, using those percentages:
Quote:Reposted from the Iwata Asks thread:
So, we know how power save works now (it's basically the same as dynamic contrast on LCD TVs) and Streetpass isn't constantly communicating. We can roughly guess the battery life.
3D: 3-5 hours (4.2 hours with WiFi on constantly) (Highest Brightness is 4 hours with power save on)
2D: 8 hours (6.5 hours with WiFi on constantly)
Not as good as I was hoping for to be honest. I weep for the PSP 2!
Also:
Quote:Iwata: The first thing (Nobuo) Nagai-san10, who's in charge at the Uji plant, said to me when he looked over the designs for Nintendo 3DS before mass production began was "This time it's fully packed right from the start."
Sugino: Oh, really? (laughs) But he was right. That's why we don't have any short-term plans for creating a more compact version of Nintendo 3DS like we did with Nintendo DS Lite. (laughs)
Iwata: Yeah. (laughs) When making Nintendo 3DS, we used all our tricks for Nintendo DS Lite—and more—for cutting down on size right from the start.