Why does a keyboard need to go to sleep.

Online I see for sale a wireless keyboard/mouse, and it says about it

"Auto Sleep And Wake Feature

This keyboard also features an auto sleep and auto wake mode. If there is a long period of inactivity, the keyboard will automatically go into a sleep mode. To exit sleep mode, press any key."

Why does it have any need to go to sleep. Why would it use any power if no one is pressing a key? This is not a cordless phone that waits for phone calls, whose battery drains even when not in use.

(For that matter. why don't cordless phones have on/off switches. They can go without charging for about 2 days. If you could rely on the ringer in the other room and turn the cordless phone OFF, they wouldnt' need a charge for 10 days or more. )

This is the item. Before you buy it, there's a newer version now.

Thanks.

Sleep IS not using "much" power. The only difference is that the first keystroke may take a fraction of a second to switch the clock and get everything running again. Don't worry about it. It's doing what you want.

This is not a cordless phone that waits

My cordless phones do go 10 days or more. I have two phones and one charger. I just swap them every couple of weeks.

So since the keyboard isn't using much power except when someone is pushing a button, it's always asleep the rest of the time, is that right?

A remote control needs a clock?

What are you, a 1950's doctor?

Do they have on-off switches. If they go two weeks without one, they'd

10 weeks with one.

This device is more complex than a remote control. It sends keystrokes to the computer but also receives data. When you connect the device, the computer will send configuration data such as data rate, auto-repeat time, state LEDS, mouse speed, acceleration etc. When you press for example CapsLock, the keyboard sends the caps command to the computer, then receives the request to toggle the CapsLock LED. All that activity needs the RF section to be powered and active, so it makes sense to provide a sleep mode that paces down this activity.

Cheers!

I don't think he means a clock as in telling the time. It's clock in a more general form of a timing signal to run the processor.

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Thanks. And thanks everyone for their help

It scans, as in sequential pulses tto the switches. they don't really chang e states much unless a key is pressed but insid the processor thigs are cha ging states. That means capacitanc is loading it down, even though there is no resistive load. Stop that process and it cools down and pulls less powe r.

The world is getting into "green" and using/wasting less energy. they are of the mond that if a million people save a milliwatt we have collectively saved a kilowatt. Engieers, seriously, sit there and figure out how to save that milliwatt. it is partly PR and partly the governments. I hear the alm ost made it illegal to sell plasma TVs in the EU because they are so damn p ower hungry. AND GUESS WHY.

Remember about the scanning pulses and the capacitance ? Well plasma TVs ar e all about scanning and capacitance. I mean that is ALL they are about and in spades. A couple hundred volts at high speed applied to highly capaciti ve loads. It literally pulls as much juice as a old deflection yoke and hig h voltage circuit would.

and another ting when it comes to a keyboard, look on the bottom and see if f maybe it has a battery compartment. Seriously, some of them, even high en d ones, some have a place where you can stick like eight or ten "D" cells. Do you know what good alkaline "D" cells cost ? And even in the absece of t hat, most of them run off DC so they know it might be run off of batteries someday.

that makes it a feature, actually for the customer. It is not so much that you are going to save 0.0003 cents on your electric bill next month, it mig ht be that $15 you save on batteries next month.

Who's going to be able to detect that against their megawatts of background?

Mike.

A wireless keyboard uses Bluetooth to communicate with the computer. This takes energy and drains the battery eventually.

What the keyboard does is it goes into a low power mode where the Bluetooth transceiver is shut down, and the keyboard likely only scans for presses once a second or so. So now you are down to the microamp power load and batteries can provide that for along time, compared to milliamps of draw when busy with Bluetooth and keystrokes.

Cordless phones do have low power mode, but they still have to 'listen' for the RF signal to wake them up, and a receiver does draw more power than simply sleeping.

Cell phones low power mode still transmits and receives RF so the various features are kept up to date - location, chat with local cell towers to keep the device able to receive, etc.

John :-#)#

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Many don't. Some use non-bluetooth RF (and some use IR but I wasn't talking about those) but I apreciate the rest of your post.

They don't have to, if the user is able to hear the "bell" on the base station or any other sounder he's installed.

Cell phones rarely if ever have extensions and certainly don't have base stations whose bells you can hear. But even they can be turned off so they neither transmit nor receive. That's what I would like in a cordless phone and a keyboard.

Here is one wireless keyboard that does have an off-switch.

"12-month battery life - You can go a full year doing the things you love without battery hassles. An on/off switch helps you save power when

thing. They made this for when people watch tv and they know that's only a small part of the time.

The brief pdf file says "Power Off and power On the keyboard."

Don't they mean all the way off?

(BTW, this is a lot bigger than the one I asked about, but its rows of keys are offset like standard keyboards, and it will be a lot easier to type on. Actually there are a lot of full size ones and only a few little ones. Like all of them so far, it only claims a 10 meter range, so I'd have to put some sort of USB extension to make the USB receiver close enough to the keyboard.)

You're right about that. I hate filling something with batteries. I hate using batteries at all. When I was little, the only thing that ran on batteries was a flashlight (and the car starter) and we only had one of each.

At least one model keyboard said it took 2 AAA, which is not bad

The second one I mentioned, in the other post, is big, and I have the image that it must need more batteries because it sends big bursts of radio waves instead of the tiny bursts that the tiny keyboard must use. And the keyboard is longer too, so it probably uses more energy to get from one end to the electronics at the other end. So it needs more batteries. At least that's how it feels.

The webpage for that other one says "Enjoy using the keyboard for a full year** without the hassle of changing batteries. The on/off switch also helps you save power when the keyboard is not in use. ... ** Keyboard battery life calculation based on an estimated two million keystrokes/year in an office environment. User experience may vary."

If I do 4000 keystrokes a year, I'll be surprised. I wish I knew if it was a standard battery. Here it is, 2 AA batteries. That's okay.

My father bought in the '50's a tube radio that also ran on batteries. The tube names began with 1 and 2, and maybe one was 5 because that was the voltage the heaters used. It used two rectangular cells, and when I was in college I thought I'd fix it up. One of them was $3 in 1966 and the 42-volt battery was for sale but it was $42 or so. That's about $420 dollars in today's money, so I gave up the plan

Simply put: wouldn't YOU get tired of people banging on your head all day?

Never tried it unless you count trying to watch TV during election time. Actually, now that I stopped watching TV I guess my head feels a little bit better.