Super Low Voltage Driving Of Displays
First Claim
1. A display device (500) comprising:
- a plurality of switches (510), each of the switches comprising an operational terminal (D) and controlling a voltage on said operational terminal (D);
a plurality of pixels (555), each having a pixel state (P) that is driven by a driving voltage differential (VEP) between a pixel voltage (Vpx) applied to a pixel terminal (101) of the pixel and a common voltage (VCE) applied to a common terminal (102) of the pixel, said pixel terminal being coupled to a corresponding operational terminal (D) of the switch;
a common driver (570) for providing a variable common voltage (VCE) to the common terminals (102); and
a controller (515) controlling the switches (510) for driving the plurality of pixels (555), the controller (515) being arranged to control the common driver in a first pixel driving state (1120), wherein pixels are driven to a first colour, to provide a common voltage to the common terminals with a first polarity and to control the common driver in a second pixel driving state (1140), wherein pixels are driven to a second colour, to provide a common voltage to the common terminals with a second polarity opposite to the first polarity, wherein a swing on the common voltage is larger than a swing on the pixel voltage.
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Accused Products
Abstract
A display device (500) is described with a plurality of pixels (555), each having a pixel state (P) that is driven by a driving voltage differential (VEP) between a pixel voltage (Vpx) applied to a pixel terminal (101) of the pixel and a common voltage (VCE) applied to a common terminal (102) of the pixel. In a first pixel driving state, wherein pixels are driven to a first colour, a common voltage is provided to the common terminals (102) with a first polarity. In a second pixel driving state, wherein pixels are driven to a second colour, a common voltage is provided to the common terminals (102) with a second polarity opposite to the first polarity. An absolute value of the common voltage (VCE) in the first and second pixel driving state is higher than a maximum absolute value of the column voltage (Vcol) in the corresponding pixel driving state.
25 Citations
19 Claims
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1. A display device (500) comprising:
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a plurality of switches (510), each of the switches comprising an operational terminal (D) and controlling a voltage on said operational terminal (D); a plurality of pixels (555), each having a pixel state (P) that is driven by a driving voltage differential (VEP) between a pixel voltage (Vpx) applied to a pixel terminal (101) of the pixel and a common voltage (VCE) applied to a common terminal (102) of the pixel, said pixel terminal being coupled to a corresponding operational terminal (D) of the switch; a common driver (570) for providing a variable common voltage (VCE) to the common terminals (102); and a controller (515) controlling the switches (510) for driving the plurality of pixels (555), the controller (515) being arranged to control the common driver in a first pixel driving state (1120), wherein pixels are driven to a first colour, to provide a common voltage to the common terminals with a first polarity and to control the common driver in a second pixel driving state (1140), wherein pixels are driven to a second colour, to provide a common voltage to the common terminals with a second polarity opposite to the first polarity, wherein a swing on the common voltage is larger than a swing on the pixel voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for driving a display device (500) comprising:
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a plurality of switches (510), each of the switches comprising an operational terminal (D) and controlling the voltage on said operational terminal (D); a plurality of pixels (555), each having a pixel state (P) that is driven by a driving voltage differential (VEP) between a pixel voltage (Vpx) applied to a pixel terminal (101) of the pixel and a common voltage (VCE) applied to a common terminal (102) of the pixel, the pixel terminal being coupled to a corresponding operational terminal (D) of the switch; a common driver (570) for providing a variable common voltage (VCE) to the common terminals (102); the method comprising;
controlling the switches for driving the plurality of pixels (555) and controlling the common driver (570) in a first pixel driving state (1120), wherein pixels are driven to a first colour, to provide a common voltage to the common terminals with a first polarity and in a second pixel driving state (1140), wherein pixels are driven to a second colour, to provide a common voltage to the common terminals with a second polarity opposite to the first polarity, wherein a swing on the common voltage, is larger than a swing on the pixel voltage.- View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
the method comprising the step of controlling the operation of the column driver (530), the row driver (520), and the common driver (570) for driving the plurality of pixels (555), such that the swing on the common voltage, is larger than a swing on the column voltage, i.e. an absolute value of the difference between a maximum column voltage and a minimum column voltage, which can be provided by the column driver.
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13. A method according to claim 12, wherein a swing on the row voltage, i.e. an absolute value of the difference between the row select voltage and the row non-select voltage is larger than a swing on the column voltage, i.e. an absolute value of the difference between a maximum column voltage and a minimum column voltage, which can be provided by the column driver during the first and the second driving state, in such a way that the semiconducting switching devices (510) can be switched in their conducting state and in their non-conducting state irrespective of column and pixel voltage levels.
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14. A method according to claim 12, comprising the further step of controlling a storage driver of the display device for providing a storage voltage (Vst) to a storage capacitor (Cst), connected between the storage driver and the pixel terminal (101) of the pixel and having a storage voltage swing (Δ
- Vst) being proportional to a common voltage swing, to change the pixel voltage (Vpx) with proportional amplitude to and at substantially the same time as the common voltage, with proportional amplitude to and at substantially the same time as the common voltage.
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15. A method according to claim 14, further comprising controlling the common driver (570) and storage driver during a start up phase (1110) for an image update before the first or second pixel driving state, in a first step (1210) to change the common voltage and the storage value to such a value that a value of the pixel voltage is changed to a value that keeps the semiconducting switching device (510) in its non-conducting state, controlling the column driver (520) in at least one reset step (1220) to reset the value of the pixel voltage and controlling the common driver (570) and storage driver in a second step (1230) to change the value of the common voltage and the storage voltage to the value corresponding to the first or second driving state, which ever is applicable.
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16. A method according to claim 15, wherein the common driver and storage driver are controlled during the start up phase, in a third step (1710), which is executed before the first step, to provide a common voltage and a storage voltage, enabling the provision of a zero voltage over the pixels or to provide a common voltage with a polarity opposite to the polarity of the common voltage during the remainder of the start-up phase.
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17. A method according to claim 14, further comprising controlling the common driver (570) and the storage driver during a transition phase (1130,1150) from the first to the second pixel driving state or vice versa, to change the value of the common voltage and storage voltage in a number of steps (1310) from the value corresponding to the first pixel driving state to the second pixel driving state or vice versa, each of the stepwise value changes of the common voltage and storage voltage resulting in a value change of the pixel voltage, and controlling the column driver (520) in at least a reset step (1320) between the steps to change the column voltage in such a way that the value of the pixel voltage is changed in a direction opposite to the direction of the value change of the pixel voltage caused by the value change of the common voltage and storage voltage.
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18. A method according to claim 14, further comprising controlling the common driver (570) and storage driver during a shutdown phase (1160) at the end of an image update after the first or second pixel driving state to change the absolute value of the common voltage and storage voltage in a number of steps to their final values, each of the stepwise value changes of the common voltage and storage voltage resulting in a value change of the pixel voltage, and controlling the column driver (520) in at least a reset step between the steps to change the column voltage in such a way that the value of the pixel voltage is changed in a direction opposite to the direction of the value change of the pixel voltage caused by the value change of the common voltage and storage voltage.
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19. A method according to claim 18, wherein the common driver (570) and storage driver are controlled, during the shutdown phase, in a further step (1810) to provide a common voltage and a storage voltage, enabling the provision of a zero voltage over the pixels or to provide a common voltage with a polarity opposite to the polarity of the common voltage during the remainder of the shutdown phase.
Specification