Low-power e-paper displays provide the perfect solution for slow-changing data

30 Nov 2020

Most information is time-dependent in some way. Last week’s shopping list is largely useless a week later but knowing the time and location of tomorrow’s appointments is critical today.

And not all information is static – a list may evolve (and normally does while walking around the store), and you might move or cancel appointments quite frequently.

Being time-dependent also means something can change over time, however slowly. Data is a good example as its value may change over time. This means it has value on two levels: its value at any given time, and the amount it has changed over a period of time.

Often we are most concerned with the former. Take the weather, for example – we know it changes constantly, but at any given time it is the current temperature and rainfall that most people will be interested in. Accessing and sharing this information has occupied human minds for millennia, leading to any number of dials, gauges and displays capable of relaying the temperature at varying levels of detail. Fundamentally, the complexity of the solution can easily outweigh the value of the data. So wouldn’t it be simpler to make it, well, simple?


Adding efficiency to smart information

Essentially, a room thermostat needs to display two figures: the target temperature and the actual temperature. Thermal dynamics means that unless there is an emergency situation in progress, the current temperature is unlikely to change very quickly. So is it really an efficient use of energy to have a visual display that needs a constant supply of power, just to show the same thing for hours on end?

Many people would agree it is not, but is there an alternative? Actually, there is. E-paper is a bi-stable display technology; it can occupy one of two states without power being applied. This means that an e-paper display can effectively show the same temperature for years if necessary without any power being consumed, but can change at the metaphorical flick of a switch.


Low-power displays for smart meters

Using a screen like our 1.44-inch display as the basis for a room thermostat clearly makes sense, but the benefits don’t stop there. In an effort to encourage consumers to think more carefully about the energy they use on a daily basis, governments around the developed world are using smart meters. Smart meters monitor utilities including electricity, water and gas, displaying the amount of the utility consumed and the cost to the user. If utility companies give consumers access to the cost information at any given moment, consumers will consider their energy usage more carefully.


Traditional electromechanical meter vs. smart meter with a Pervasive Displays EPD

It makes sense, therefore, to use the most energy-efficient form of display possible in a smart meter. With its ultra-low power consumption and wide 180° viewing angle, something like the 3.7-inch display would be ideal.


The perfect energy-efficient display solution

No other form of display comes close to the energy efficiency of an e-paper display. In an application like a thermostat or smart meter, where the information is a snapshot of instantaneous usage, it provides the perfect solution.