Most power efficient display of single digits and color flap

[izico]

I'm redesigning a board game toy now.

The first version use color flaps rotated by shaft to show color, red or blue, and it uses 7 segment LED to display a single digit of player score.

I'm thinking of replacing the color flap with red and blue LED or other means to show these 2 colors.

But we want the battery to last as long as possible.

And of course a MCU will be used for control.

Anybody have better idea about how to keep the power consumption as small as possible to have the battery replacement few? Any means are open, mechanical or electrical or else, the LED current consumption is too high, 1ma is just a very dim color on LED, and we have 18 color flaps to be replaced, it's a lot current consumption.

 

[BradtheRad]

Flash the led briefly, strobe style.

 

[izico]

Flashing LED is not good option as it distract the player as this board game is a strategic game that needs concentration of brain power.

 

[KlausST]

Hi,

Maybe a hack like this:
Use a 7 segment transflective LCDisplay. Disassemble the polarization filter and mount a new polarization filter, but 90° rotate with respect to the old one.
Now all of the display is black, only the active segments are clear.

Use multicolor LED as backlight. There are ready to buy multicolor LED backlight modules with diffuser..
******
Or use a graphical colored display (OLED?) and "design" your 7 segment bitmaps.

Klaus

 

[izico]

I have forgotten to say the current board size is 11"x8.5", and the color flaps is about 3" long with red and blue flaps crossed diagonally in the center of a 3x3 squares.

This needs quite large LCD which is in fact no less current than a single LED enclosed inside a same color enhancing plastic cover, and the cost of such large LCD is inhibitive.

There seems only another choice to rotate the color flaps by an electromechanical method now, I'm investigating if an affordable method can be found besides motors control.

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I have forgotten to tell the board is 11"x8.5" in size, with this size the LCD cost is inhibitive.

So it seems only 2 choices now:
1. Color LED enclosed in same color plastic cover which tend to enhance the same color, and bundle together with a large rechargeable battery with high voltage such as the 9v battery used in many multimeters, and bundle a charger circuit or even a charger together like how the mobile phone is sold.

The current consumption will be some tens ma but with a 9v 1000mah battery it can still last some hundreds hours, it's still OK for mist users.

2. Some electromechanical method to rotate the color flaps, by now I have not thought of any affordable solution, but motor control is an obvious solution though quite inhibitively expensive.

 

[betwixt]

If you can afford to lose some brightness, use a shutter arrangement. Basically your flap has alternate red and blue stripes and over it you use another fixed transparent flap with black stripes across it. All the stripes are the same width. When the movable flap is in one position, the red is under the black and the blue is visible, move the flap slightly and the blue is under the black and the red is visible. It has the advantage of only needing negligible movement (maybe a tiny solenoid or modified electrical relay) and with some careful planning can be a "push or pull" mechanism that needs no power except when actually moving the flap.

If you decide to use LEDs, you only need one LED of each color per square, you can direct the light towards a frosted screen to diffuse it.

Brian.

 

[BradtheRad]

Flashing LED is not good option as it distract the player as this board game is a strategic game that needs concentration of brain power.

It is common to make the frequency so fast that the eye sees a continual light. Say 30 Hz.

 

[izico]

I have forgotten this eye property, yes using 18 PWM channels to drive with adjustable frequency and duty cycles is the best to decrease power consumption, and the PWM channel can still work when the MCU is put into deep sleep mode for some MCU models, or a separate PWM modulator chip can be used if no appropriate low power consumption MCU can be found to have 18 PWM channels working in sleep mode.

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But in fact flashing LED is the same to drive the LED with smaller current, the effect on human eye is the same, so in fact this is not at all useful and it complicate design.

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On physicsforum one recommend flipdot to me, it's the best technically but design and BOM cost is quite high, so I have decided to use LED + high voltage rechargeable battery + charger solution, this looks the most economical.