1. Technical Field
The technical field relates to a display. Particularly, the technical field relates to a driving method of a multi-stable display.
2. Related Art
In collaboration with driving timings of the scan lines S(1)-S(N), the data driver 110 correspondingly writes a plurality of pixel data into pixels through the data lines D(1)-D(M). For example, when the scan driver 120 drives the scan line S(1), the data driver 110 correspondingly writes pixel data into a pixel PX through the data line D(M).
Regarding the multi-stable display medium (for example, the cholesteric liquid crystal) display, a right-slope of the reflectivity-voltage characteristic curve is generally used as a threshold for driving the pixels, i.e. a range of the voltage difference (the horizontal axis) of
Accordingly, the disclosure is directed to a driving method of a multi-stable display, by which a driving voltage is effectively reduced to ameliorate a situation of excessive frequency required when a conventional pulse width modulation (PWM) technique is used to control multiple gray levels, and the driving method can be applied to existing STN driver integrated circuits (ICs).
The disclosure provides a driving method of a multi-stable display, which includes following steps. When a state of a pixel is not changed, a first voltage level is provided to a scan line of the pixel. When the state of the pixel is changed, a second voltage level and a third voltage level are respectively provided to the scan line in a first phase and a second phase. When the state of the pixel is set to a bright state, a fourth voltage level and a fifth voltage level are respectively provided to a data line of the pixel in the first phase and the second phase, where an absolute value of a voltage difference of the second and the fourth voltage levels is smaller than a first threshold voltage, and an absolute value of a voltage difference of the third and the fifth voltage levels is also smaller than the first threshold voltage. When the state of the pixel is set to a dark state, the fifth voltage level and the fourth voltage level are respectively provided to the data line in the first phase and the second phase, where an absolute value of a voltage difference of the second and the fifth voltage levels is greater than a second threshold voltage, and an absolute value of a voltage difference of the third and the fourth voltage levels is also greater than the second threshold voltage, and the second threshold voltage is greater than the first threshold voltage.
The disclosure provides a driving method of a multi-stable display, which includes following steps. A second voltage level and a third voltage level are respectively provided to a scan line of a pixel in a first phase and a second phase. A fourth voltage level is provided to a data line of the pixel during a data driving period, and a fifth voltage level is provided to the data line during a period other than the data driving period, where a first part period of the data driving period belongs to the first phase, and a second part period of the data driving period belongs to the second phase, and the fourth voltage level is greater than the fifth voltage level.
According to the above descriptions, since a left-slope of a reflectivity-driving voltage characteristic curve is used to drive pixels, the driving voltage can be effectively reduced. Moreover, in the exemplary embodiment, a gray level of a pixel is controlled by adjusting a phase relationship of pulses of the data line and the scan line, so as to ameliorate a situation of excessive frequency required when the conventional PWM technique is used to control multiple gray levels. The driving method of the multi-sable display of the exemplary embodiment can be applied to the existing STN driver ICs.
In order to make the aforementioned and other features of the disclosure comprehensible, several exemplary embodiments accompanied with figures are described in detail below.
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
As described in the related art, a driving method of a current multi-stable display generally uses the right-slop (with a range from VC to VD) of the reflectivity-driving voltage characteristic curve of
If the state of the pixel PX is to be changed to a dark state (a non-reflective state), the scan line S(1) provides a second voltage level V2 to the pixel PX in the first phase P1 and provides a third voltage level V3 to the pixel PX in the second phase P2. The data line D(M) provides a fifth voltage level V5 to the pixel PX in the first phase P1 and provides a fourth voltage level V4 to the pixel PX in the second phase P2, as that shown in
If the state of the pixel PX is to be changed to the bright state (the reflective state), the scan line S(1) provides the second voltage level V2 to the pixel PX in the first phase P1 and provides the third voltage level V3 to the pixel PX in the second phase P2. The data line D(M) provides the fourth voltage level V4 to the pixel PX in the first phase P1 and provides the fifth voltage level V5 to the pixel PX in the second phase P2, as that shown in
In
In the present embodiment, the first voltage level V1, the second voltage level V2, the third voltage level V3, the fourth voltage level V4 and the fifth voltage level V5 are all positive voltages (i.e. greater than or equal to 0 volt). Voltage values of the first voltage level V1, the second voltage level V2, the third voltage level V3, the fourth voltage level V4 and the fifth voltage level V5 can be determined according to an actual design requirement. For example, the first voltage level V1 can be 20 volts, the second voltage level V2 can be 40 volts, the third voltage level V3 can be 0 volt, the fourth voltage level V4 can be 30 volts, and the fifth voltage level V5 can be 10 volts. If the voltage level of 20 volts is provided to the scan line S(1) of the pixel PX in both of the first phase P1 and the second phase P2, the absolute values of the voltage differences of the pixel PX are |20−30| and |20−10|, and neither of |20−30| and |20−10| is greater than the first threshold voltage VA (for example, 10 volts), so that the state of the pixel PX is maintained to the bright state. If the voltage level of 40 volts and the voltage level of 30 volts are respectively provided to the scan line S(1) and the data line D(M) in the first phase P1, the absolute value of the voltage difference of the pixel PX is |40−30|. If the voltage level of 0 volt and the voltage level of 10 volts are respectively provided to the scan line S(1) and the data line D(M) in the second phase P2, the absolute value of the voltage difference of the pixel PX is |0−10|. Regardless of |40−30| or |0−10|, neither of which is greater than the first threshold voltage VA, so that the state of the pixel PX is maintained to the bright state. If the voltage level of 40 volts and the voltage level of 10 volts are respectively provided to the scan line S(1) and the data line D(M) in the first phase P1, the absolute value of the voltage difference of the pixel PX is |40−10|. If the voltage level of 0 volt and the voltage level of 30 volts are respectively provided to the scan line S(1) and the data line D(M) in the second phase P2, the absolute value of the voltage difference of the pixel PX is |10−30|. Regardless of |40−10| or |0−30|, both of which are greater than the second threshold voltage VB (for example, 20 volts), so that the state of the pixel PX is maintained to the dark state.
Under a premise that the scan line S(1) is provided with the aforementioned driving waveforms, in order to change the state of the pixel PX to a gray state, the fourth voltage level V4 is provided to the data line D(M) during a data driving period DP, and the fifth voltage level V5 is provided to the data line D(M) during a period other than the data driving period DP. A part of the data driving period DP (i.e. a first part period DP1 shown in
In the present embodiment, time lengths of the data driving period DP, the first phase P1 and the second phase P2 are equivalent. In other embodiments, the time lengths thereof can be arbitrarily adjusted according to a design requirement. Moreover, in the present embodiment, the time lengths of the first part period DP1 and the second part period DP2 are equivalent. By adjusting the time length of the data driving period DP, the gray level of the pixel PX can be determined, and the time lengths of the first part period DP1 and the second part period DP2 are not equivalent.
If the phase of the pulse of the data line D(M) is advanced, i.e. the time length of the first part period DP1 is greater than that of the second part period DP2, an average of the voltage difference of the pixel PX is close to the driving voltage of the bright state, so that the reflectivity (reflectivity of a first gray state) of the pixel PX is greater than the reflectivity of the second gray state. If the state of the pixel PX is to be changed to the bright state, the time length of the second part period DP2 is adjusted to be 0 (i.e. the whole data driving period DP belongs to the first phase P1).
Comparatively, if the phase of the pulse of the data line D(M) is postponed, i.e. the time length of the first part period DP1 is smaller than that of the second part period DP2, the average of the voltage difference of the pixel PX is close to the driving voltage of the dark state, so that the reflectivity (reflectivity of a third gray state) of the pixel PX is smaller than the reflectivity of the second gray state. If the state of the pixel PX is to be changed to the dark state, the time length of the first part period DP1 is adjusted to be 0 (i.e. the whole data driving period DP belongs to the second phase P2).
In the above embodiment, one pixel is taken as an example for descriptions. Those skilled in the art can arrange driving timings of the scan lines S(1)-S(N) and the data lines D(1)-D(M) according to the aforementioned instructions. For example,
In the embodiment of
Voltage values of the second voltage level V2 and the third voltage level V3 can be determined according to an actual design requirement. For example, the second voltage level V2 can be 40 volts, and the third voltage level V3 can be 0 volt. Therefore, in the first phase P1 of the reset period R, the absolute value of the voltage difference of the pixel PX is |40−0|1. In the second phase P2 of the reset period R, the absolute value of the voltage difference of the pixel PX is |0−40|. Regardless of |40−0| or |0−40|, both of which are greater than a fourth threshold voltage VD (referring to
In summary, since the left-slope (with a range from VA to VB) of the reflectivity-driving voltage characteristic curve of
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.