Method of compensating temperature dependence of driving schemes for electrophoretic displays
View Patent ↗An image is updated on a bi-stable display ( 310 ) such as an electrophoretic display by providing separate scaling functions (SF 1 , SF 2 ) for scaling a duration of a reset pulse (R) and a duration of a driving pulse (D) in a drive waveform based on temperature ( 335 ). An absolute value of a slope with varying temperatures of the scaling factor (SF 1 ) for the reset pulse (R) is significantly greater than that of the scaling factor (SF 2 ) for the driving pulse (D), while both scaling factors increase with decreasing temperature. Image update time (IUT) is significantly reduced at lower temperatures, while a range of variation of IUT across all temperatures is also reduced. Scaling functions (SF 3 , SF 4 ) may also be used for scaling a duration of a help reset pulse (H) and/or a duration of one or more shaking pulses (SH 1 , SH 2 ).
1. A method for driving a bi-stable display, comprising:
determining a temperature (T) associated with the bi-stable display ( 310 );
determining a duration for applying a reset pulse (R) to at least a portion of the bi-stable display based on the determined temperature and a first scaling function (SF 2 ); and
determining a duration for applying a driving pulse (D) to the at least a portion of the bi-stable display based on the determined temperature and a second scaling function that differs from the first scaling function (SF 2 ), wherein an absolute value of a slope of the first scaling function with varying temperature is less than an absolute value of a slope of the second scaling function when the determined temperature is below a reference temperature (T ref ).
2. The method of claim 1 , wherein:
the determining the duration for applying the reset pulse comprises determining a first scaling factor according to the first sealing function (SF 2 ) and the determined temperature (T), and scaling a reference reset pulse duration by the first scaling factor; and
the determining the duration for applying the driving pulse comprises determining a second scaling factor according to the second scaling function (SF 1 ) and the determined temperature (T), and scaling a reference driving pulse duration by the second scaling factor; wherein the first scaling factor is less than the second sealing factor when the determined temperature is below a reference temperature (T ref ).
3. The method of claim 1 , further comprising:
determining a duration for applying shaking pulses (SH 1 , SH 2 ) to the at least a portion of the bi-stable display based on the determined temperature and a further scaling function (SF 4 ).
4. The method of claim 3 , wherein:
the further scaling function (SF 4 ) has an opposite slope with varying temperature than slopes of the first and second sealing functions over at least a portion of a temperature range.
5. The method of claim 1 , further comprising:
determining a duration for applying a help pulse (H), prior to the reset pulse, to the at least a portion of the bi-stable display based on the determined temperature and a further scaling function (SF 3 ).
6. The method of claim 5 , wherein:
the further sealing function (SF 3 ) lies between the first (SF 2 ) and the second (SF 1 ) scaling factors.
7. The method of claim 1 , wherein:
the bi-stable display comprises an electrophoretic display.
8. A program storage device tangibly embodying a program of instructions executable by a machine to perform a method for updating an image on a bi-stable display, the method comprising:
determining a temperature(T) associated with the bi-stable display( 310 );
determining a duration for applying a reset pulse (R) to at least a portion of the bi-stable display based on the determined temperature and a first scaling function (SF 2 ); and
determining a duration for applying a driving pulse (D) to the at least a portion of the bi-stable display based on the determined temperature and a second scaling function (SF 1 ) that differs from the first scaling function (SF 2 ), wherein an absolute value of a slope of the first scaling function with varying temperature is less than an absolute value of a second scaling function when the determined temperature is below a reference temperature (T ref ).
9. The program storage device of claim 8 , wherein:
the determining the duration of the reset pulse comprises determining a first scaling factor according to the first scaling function (SF 2 ) and the determined temperature (T), and scaling a reference reset pulse duration by the first scaling factor; and
the determining the duration of the driving pulse comprises determining a second scaling factor according to the second scaling function (SF 1 ) and the determined temperature (T), and scaling a reference driving pulse duration by the second scaling factor; wherein the first scaling factor is less than the second scaling factor when the determined temperature is below a reference temperature (T ref ).
10. The program storage device of claim 8 , wherein the method further comprises:
determining a duration for applying shaking pulses (SH 1 , SH 2 ) to the at least a portion of the bi-stable display based on the determined temperature and a further scaling function (SF 4 ).
11. The program storage device of claim 8 , wherein the method further comprises:
determining a duration cur applying a help pulse (H), prior to the reset pulse, to the at least a portion of the bi-stable display based on the determined temperature and a further scaling function (SF 3 ).
12. The program storage device of claim 8 , wherein:
the bi-stable display comprises an electrophoretic display.
13. An electronic reading device, comprising: a bi-stable display ( 310 ); and
a control ( 100 ) for updating an image on the bi-stable display by: (a) determining a temperature (T) associated with the bi-stable display, (b) determining a duration for applying a reset pulse (R) to at least a portion of the bi-stable display based on the determined temperature and a first scaling function (SF 2 ), and (e) determining a duration for applying a driving pulse (D) to the at least a portion of the bi-stable display based on the determined temperature and a second scaling function (SF 1 ) that differs from the first scaling function, wherein an absolute value of a slope of the first scaling function with varying temperature is less than an absolute value of a slope of the second scaling function when the determined temperature is below a reference temperature (T ref ).
14. The electronic reading device of claim 13 , wherein:
the determining the duration of the reset pulse comprises determining a first scaling factor according to the first scaling function and the determined temperature, and scaling a reference reset pulse duration by the first scaling factor; and
the determining the duration of the driving pulse comprises determining a second sealing factor according to the second scaling function and the determined temperature, and scaling a reference driving pulse duration by the second scaling factor; wherein the first scaling factor is less than the second scaling factor when the determined temperature is below a reference temperature (T ref ).
15. The electronic reading device of claim 13 , wherein the control updates the image on the bi-stable display by determining a duration for applying shaking pulses (SH 1 , SH 2 ) to the at least a portion of the bi-stable display based on the determined temperature and a further scaling function (SF 4 ).
16. The electronic reading device of claim 13 , wherein the control updates the image on the bi-stable display by determining a duration for applying a help pulse (H), prior to the reset pulse, to the at least a portion of the bi-stable display based on the determined temperature and a further scaling function (SF 3 ).
17. The electronic reading device of claim 13 , wherein:
the bi-stable display comprises an electrophoretic display.