An energy-efficient proposal for digital clocks in public display systems

In this era of digitisation, digital technology is successfully replacing analog tools and equipments. The conventional digital display clocks used in public display systems like bus-stops and railway-platforms are lagging far behind in terms of modernisation in technology. The idea proposed in this paper solely relates to the reduction in power required to drive these digital clocks which can be understood by the application of primary mathematical reasoning concepts only. For indicating time in the digital style, two prevalent formats are the 24 hour format and the 12 hour format of time display. On critical investigation of the power required to drive these two digital clocks, we arrive at a conclusion that the 24 hour format clock is more energy-efficient by 6% than its 12 hour format counterpart. Energy-efficiency in this report refers to the power that is dissipated in illuminating the LEDs or other light-generating elements used to construct this digital clock. There is always a trade-off between user-convenience and the power requirement. The merit of the proposed solution lies here, whereby it takes care of both, the convenience of the user who is more familiar with the 12 hour display format as well as the power required in order to drive such a digital clock. Moreover, the 24 hour format requires an additional flip-flop as compared to the 12 hour format. Power saving may further be improved by reducing the frequency of display (a blinking system) and also by using Mod 10 and Mod 12 Gray counters as we know that Gray counters are highly power efficient due to fewer transitions. The proposed methodology saves us 46.15% of energy compared to the existing 12 hour display format and 42.20% energy with respect to the 24 hour display format. Mathematical explanations to justify the above details have been assembled in the latter half of the paper. Final conclusions have been drawn regarding the effectiveness of the proposed solution and future scope of work in this area has been discussed.