Towards Greening the Digital Display System
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This document discusses strategies to reduce power consumption in LED dot matrix display systems through techniques such as adjusting duty cycles, frame rates, and system frequencies. It highlights the significant energy usage of digital displays and proposes that optimal configurations can maintain aesthetic quality while saving power. Future work aims to explore additional factors influencing LED display efficiency.
![Towards Greening the Digital Display System
Tarik Reza Toha1, Salman Estyak2, Md. Abdullah Al Alamin3, Md. Hasanul Islam4,
Md. Abdullah Al Maruf5, Swarnendu Saikat Nandi6, Amit Chakraborty7, and A. B. M. Alim Al Islam8
Department of CSE, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh
Email: 1tarik.toha@gmail.com, 2salman.estyak@gmail.com, 3mdabdullahalalaminp@gmail.com, 4hasanuli10@gmail.com,
5ropymaruf2010@gmail.com, 6saikat.buet.cse@gmail.com, 7amitchakraborty074@gmail.com, and 8alim_razi@cse.buet.ac.bd
Background
•Digital displays stand for modernization of city and
digital era
• It has versatile applications such as displaying information
on electronic equipment and instrument panels,
advertisements on billboards, etc.
•The display is one of the components in an electronic
device, which has the highest percentage of total
energy consumption [1], [2]
• The study in [3] concludes that a digital billboard can
consume up to 30 times the energy that an average
American home uses in a year
1. Google Glass Snoopers Can Steal Your Passcode With a Glance, March, 2015. Available:
http://www.wired.com/2014/06/google-glass-snoopers-can-steal-your-passcode-with-a-
glance/
2. B. Hoanca and K. Mock. Password Entry Scheme Resistant to Eavesdropping, Security
and Management, Las Vegas, Nevada, 2008, pp. 119-125.
3. L. Sobrado, J. C. Birget, "Graphical passwords", The Rutgers Scholar, An Electronic
Bulletin for Undergraduate Research, vol. 4 (2002).
4. N. Hopper and M. Blum. A Secure Human-Computer Authentication Scheme. Technical Re-
port CMU-CS-00-139, Carnegie Mellon University, 2000.
Proposed Methodology
•While displaying a character on a LED dot matrix by
row-wise, we have to select a single row in every
frame period to print the corresponding pattern of that
frame
• Thus, every frame period requires power to display the
frame
•By pausing the row selection for a small portion of a
frame period (say, the duty cycle is 95%), the
brightness of the display does not decrease
significantly
• This technique reduces the total power consumption of a dot
matrix display system for the dimming period
•Additionally, we can green the digital display system
by decreasing the system frequency and frame period
in exchange of brightness
Experimentation and Findings
•We investigate the impact of duty cycle change on
luminous efficacy in a 2 x 4 dot matrix display
module
• We use shift registers and
Darlington transistor arrays
in order to reduce the total
power requirement of our
display module
Conclusion and Future Work
•We attempt to reduce the power consumption of a
LED dot matrix display system by varying all
possible parameters such as duty cycle, frame rate,
and system frequency
•We found that the optimal point is 85% duty cycle,
50 Hz frame rate, and 16 MHz system frequency,
which keeps the display aesthetic enough
•We plan to find more contributing factors of the LED
display system such as LED temperature, etc., which
will lead the system greener
References
NSysS 2017, January 5-8, 2017, Dhaka, Bangladesh
1. Carroll, A. and Heiser, G., 2010, June. An Analysis of Power Consumption in a
Smartphone. In USENIX annual technical conference (Vol. 14).
2. Pitt, M.G., Zehner, R.W., Amudson, K.R. and Gates, H., 2002, May. 53.2: Power
Consumption of micro‐encapsulated Display for Smart Handheld Applications. In SID
Symposium Digest of Technical Papers (Vol. 33, No. 1, pp. 1378-1381). Blackwell
Publishing Ltd.
3. Young, Gregory. "Illuminating the Issues Digital Signage and Philadelphia’s Green
Future." (2010).
4. Dot Matrix Display datasheet. https://goo.gl/RpGnLj. Accessed: Dec. 03, 2016
5. US Department of Energy. LED Dimming. https://goo.gl/YCsRzX.Accessed: Dec. 03, 2016
Motivation
•According to the U.S. Department of Energy, the
luminous efficacy (lumens per watt) of a Light
Emitting Diode (LED) is much higher, i.e., produces
more light than the traditional fluorescent,
incandescent, or halogen bulbs [3]
• The power hungriness of a LED display system such as dot
matrix display is still higher than any other components of
an electronic device [4]
•Dimming LED sources is an approach to enable power
saving [5]
• Pulse width modulation (PWM) operation, i.e., varying the
duty cycle is selected as the best dimming strategy [6], [7]
•However, greening the dot matrix display, the most
popular LED display system, by means of varying the
duty cycle is yet to be addressed in the literature
6. Rodrigues, W.A., Morais, L.M.F., Donoso-Garcia, P.F., Cortizo, P.C. and Seleme, S.I.,
2011, September. Comparative analysis of power LEDs dimming methods. In XI
Brazilian Power Electronics Conference (pp. 378-383). IEEE.
7. Garcia, J., Dalla-Costa, M.A., Cardesin, J., Alonso, J.M. and Rico-Secades, M., 2009.
Dimming of high-brightness LEDs by means of luminous flux thermal estimation.
IEEE transactions on Power Electronics, 24(4), pp.1107-1114.
8. Huang, W.F., 2013, February. Three approaches to light an 8× 8 LED dot-matrix
display. In Next-Generation Electronics (ISNE), 2013 IEEE International Symposium
on (pp. 37-40). IEEE.
Figure: The snapshot of our
display module
Figure: Duty cycle vs luminous efficacy per unit area while system
frequency is 16 MHz and 8 MHz respectively
• Summary of findings:
‒ With the decrease of duty cycle, system frequency, and
frame period, the illuminance decreases
‒ The minimum frame rates after flickering starts are 50 Hz
and 100 Hz for 16 MHz and 8 MHz system frequency
respectively
‒ The maximum efficacy per unit area have been achieved
when the duty cycle is 85% and 60% respectively
‒ At maximum efficacy per unit area, the amount of power
savings are 14.54% and 40%, and the brightness are
decreased by 12.5% and 37.5% respectively
• Although the overall maximum efficacy has been
achieved at 8 MHz system frequency, we can ignore it
because of its low illuminance](https://image.slidesharecdn.com/greendigitaldisplay-171115182547/85/Towards-Greening-the-Digital-Display-System-1-320.jpg)
Towards Greening the Digital Display System
- 1. Towards Greening the Digital Display System Tarik Reza Toha1, Salman Estyak2, Md. Abdullah Al Alamin3, Md. Hasanul Islam4, Md. Abdullah Al Maruf5, Swarnendu Saikat Nandi6, Amit Chakraborty7, and A. B. M. Alim Al Islam8 Department of CSE, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh Email: 1tarik.toha@gmail.com, 2salman.estyak@gmail.com, 3mdabdullahalalaminp@gmail.com, 4hasanuli10@gmail.com, 5ropymaruf2010@gmail.com, 6saikat.buet.cse@gmail.com, 7amitchakraborty074@gmail.com, and 8alim_razi@cse.buet.ac.bd Background •Digital displays stand for modernization of city and digital era • It has versatile applications such as displaying information on electronic equipment and instrument panels, advertisements on billboards, etc. •The display is one of the components in an electronic device, which has the highest percentage of total energy consumption [1], [2] • The study in [3] concludes that a digital billboard can consume up to 30 times the energy that an average American home uses in a year 1. Google Glass Snoopers Can Steal Your Passcode With a Glance, March, 2015. Available: http://www.wired.com/2014/06/google-glass-snoopers-can-steal-your-passcode-with-a- glance/ 2. B. Hoanca and K. Mock. Password Entry Scheme Resistant to Eavesdropping, Security and Management, Las Vegas, Nevada, 2008, pp. 119-125. 3. L. Sobrado, J. C. Birget, "Graphical passwords", The Rutgers Scholar, An Electronic Bulletin for Undergraduate Research, vol. 4 (2002). 4. N. Hopper and M. Blum. A Secure Human-Computer Authentication Scheme. Technical Re- port CMU-CS-00-139, Carnegie Mellon University, 2000. Proposed Methodology •While displaying a character on a LED dot matrix by row-wise, we have to select a single row in every frame period to print the corresponding pattern of that frame • Thus, every frame period requires power to display the frame •By pausing the row selection for a small portion of a frame period (say, the duty cycle is 95%), the brightness of the display does not decrease significantly • This technique reduces the total power consumption of a dot matrix display system for the dimming period •Additionally, we can green the digital display system by decreasing the system frequency and frame period in exchange of brightness Experimentation and Findings •We investigate the impact of duty cycle change on luminous efficacy in a 2 x 4 dot matrix display module • We use shift registers and Darlington transistor arrays in order to reduce the total power requirement of our display module Conclusion and Future Work •We attempt to reduce the power consumption of a LED dot matrix display system by varying all possible parameters such as duty cycle, frame rate, and system frequency •We found that the optimal point is 85% duty cycle, 50 Hz frame rate, and 16 MHz system frequency, which keeps the display aesthetic enough •We plan to find more contributing factors of the LED display system such as LED temperature, etc., which will lead the system greener References NSysS 2017, January 5-8, 2017, Dhaka, Bangladesh 1. Carroll, A. and Heiser, G., 2010, June. An Analysis of Power Consumption in a Smartphone. In USENIX annual technical conference (Vol. 14). 2. Pitt, M.G., Zehner, R.W., Amudson, K.R. and Gates, H., 2002, May. 53.2: Power Consumption of micro‐encapsulated Display for Smart Handheld Applications. In SID Symposium Digest of Technical Papers (Vol. 33, No. 1, pp. 1378-1381). Blackwell Publishing Ltd. 3. Young, Gregory. "Illuminating the Issues Digital Signage and Philadelphia’s Green Future." (2010). 4. Dot Matrix Display datasheet. https://goo.gl/RpGnLj. Accessed: Dec. 03, 2016 5. US Department of Energy. LED Dimming. https://goo.gl/YCsRzX.Accessed: Dec. 03, 2016 Motivation •According to the U.S. Department of Energy, the luminous efficacy (lumens per watt) of a Light Emitting Diode (LED) is much higher, i.e., produces more light than the traditional fluorescent, incandescent, or halogen bulbs [3] • The power hungriness of a LED display system such as dot matrix display is still higher than any other components of an electronic device [4] •Dimming LED sources is an approach to enable power saving [5] • Pulse width modulation (PWM) operation, i.e., varying the duty cycle is selected as the best dimming strategy [6], [7] •However, greening the dot matrix display, the most popular LED display system, by means of varying the duty cycle is yet to be addressed in the literature 6. Rodrigues, W.A., Morais, L.M.F., Donoso-Garcia, P.F., Cortizo, P.C. and Seleme, S.I., 2011, September. Comparative analysis of power LEDs dimming methods. In XI Brazilian Power Electronics Conference (pp. 378-383). IEEE. 7. Garcia, J., Dalla-Costa, M.A., Cardesin, J., Alonso, J.M. and Rico-Secades, M., 2009. Dimming of high-brightness LEDs by means of luminous flux thermal estimation. IEEE transactions on Power Electronics, 24(4), pp.1107-1114. 8. Huang, W.F., 2013, February. Three approaches to light an 8× 8 LED dot-matrix display. In Next-Generation Electronics (ISNE), 2013 IEEE International Symposium on (pp. 37-40). IEEE. Figure: The snapshot of our display module Figure: Duty cycle vs luminous efficacy per unit area while system frequency is 16 MHz and 8 MHz respectively • Summary of findings: ‒ With the decrease of duty cycle, system frequency, and frame period, the illuminance decreases ‒ The minimum frame rates after flickering starts are 50 Hz and 100 Hz for 16 MHz and 8 MHz system frequency respectively ‒ The maximum efficacy per unit area have been achieved when the duty cycle is 85% and 60% respectively ‒ At maximum efficacy per unit area, the amount of power savings are 14.54% and 40%, and the brightness are decreased by 12.5% and 37.5% respectively • Although the overall maximum efficacy has been achieved at 8 MHz system frequency, we can ignore it because of its low illuminance