Abstract: An image is updated on a bi-stable display (310) such as an electrophoretic display in successive frame periods by accessing data defining a set of voltage waveforms for the successive frame periods. At least a portion of the bi-stable display is driven during the successive frame periods according to the accessed data so that a longer frame period (FT, 1302, 1304, 1402, 1502, 1602, 1702, 1802) is used during at least a first portion of the voltage waveforms, and a shorter frame period (FT?) is used during at least a second portion of the voltage waveforms. For example, the longer frame period may be an elongated frame period, which is the longest period during which each of the voltage waveforms has a respective constant voltage value.

Abstract: Bi-stable electrophoretic display device (1) having a normal mode and a scrolling mode, in which image transitions are effected by causing the charged particles (8,9) to toggle between the intermediate optical states (e.g. grey-to-grey) or between an extreme optical state and an intermediate optical state (e.g. white-to-light grey), with a corresponding short update time tscroll. When the device (1) enters a scrolling mode in response to a scrolling command from a user, picture elements are first driven to a special scrolling optical. state, after which drive waveforms for scrolling mode are used for fast toggling between two scrolling states. An increased scrolling speed and very short scrolling time can be realized, without adversely affecting image quality during a normal mode.

Abstract: An image is updated on a bi-stable display (310) such as an electrophoretic display by providing separate scaling functions (SF1, SF2) 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 (SF1) for the reset pulse (R) is significantly greater than that of the scaling factor (SF2) 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 (SF3, SF4) may also be used for scaling a duration of a help reset pulse (H) and/or a duration of one or more shaking pulses (SH1, SH2).

Abstract: Bi-stable electrophoretic display device (1) having a normal mode and a scrolling mode, in which image transitions are effected by causing the charged particles (8,9) to toggle between the intermediate optical states (e.g. grey-to-grey) or between an extreme optical state and an intermediate optical state (e.g. white-to-light grey), with a corresponding short update time tscroll. When the device (1) enters a scrolling mode in response to a scrolling command from a user, picture elements are first driven to a special scrolling optical. state, after which drive waveforms for scrolling mode are used for fast toggling between two scrolling states. An increased scrolling speed and very short scrolling time can be realised, without adversely affecting image quality during a normal mode.

Abstract: Image quality is improved in an electronic reading device (300, 400), such as an electronic book using a bi-stable electrophoretic display, by determining a position to display a sub-picture (900) over a background picture (800, 810) so that like colors do not overlap. This avoids having a noticeable contrast between the color of the background picture, which may have faded since the background was displayed, and the color of the sub-picture. In another embodiment, a transition region (1310, 1320) is provided between the sub-picture (1350) and the background picture (1300) using an intermediate color, or a dithered or greyscale pattern. The background picture and sub-picture may include text and/or images.

Abstract: A technique for driving a bi-stable display (310) such as an electrophoretic display with reduced cross talk, including reduced image retention and dithering ghosting. Drive waveforms are aligned so that, during an image update period, image transitions (500, 600, 700, 800, 900) between substantially similar optical states (e.g., black-to-black) are terminated substantially later than image transitions (520, 620, 720, 920) between substantially different optical states (e.g., black-to-white). Additionally, a drive pulse in the waveforms for the transitions between the similar states compensates for cross talk caused by a drive pulse in the waveforms for the transitions between the different states. The waveforms include at least one extreme drive pulse (ED, ED1, ED2, ED3) and an additional pulse (A) of opposite polarity.

Abstract: An display device (301) has reduced memory (314) requirements for temperature compensation data. A scaling factors (433) for various temperatures and a look-up table for a waveform which is optimized to drive the grayscale for a given display temperature are stored in memory (314). The waveform for a particular temperature of the display (301) is derived from the look-up table and scaling factors (433). At some temperatures, only certain parts of the waveform need be varied, and only these parts require accurate scaling from the look-up table.

Abstract: An accurate greyscale is obtained with more natural image updates when updating a display (310) in a bi-stable electronic reading device (300,400), such as one using an electrophoretic display, by applying a first shaking pulse (S1) to the display, applying a first portion (R1) of a reset pulse to the display following the first shaking pulse (S1), applying a second shaking pulse (S2) to the display following the first portion (R1), and applying a second portion (R2) of the reset pulse to the display following the second shaking pulse (S2). The first portion may have a standard reset duration, while the second portion has an over-reset duration. A visual shock effect is avoided which would otherwise as applied after the entire reset pulse.

Abstract: An image is updated on a bi-stable display (310) such as an electrophoretic display by applying a drive waveform (900,920,940, 960; 1000, 1020,1040, 1060; 1100, 1120, 1140, 1160; 1220, 1240, 1260) with a compensating impulse (C) to at least one pixel (2) in the display. An energy of the compensating impulse depends on the image holding time, and is sufficient to restore the display to an original, pre-drift, brightness level. In one approach, the energy of the compensating impulse is determined as a predetermined function of the image holding time. In another approach, data defining different waveforms for respective different image holding times is provided in respective different look-up tables, and the data from one of the tables is selected according to the image holding time for driving the display. The compensating impulse may be provided in different portions of the drive waveform.

Abstract: Image quality is improved when updating a display image (310) in a bi-stable electronic reading device (300, 400) such as one using an electrophoretic display, by providing both monochrome and greyscale images. When an update mode of a pixel (2) of the display changes from a monochrome to greyscale, a compensating pulse (805, 825, 845, 865) is applied. The compensating pulse represents an energy based on the energy difference between: (a) an over-reset pulse (815, 835, 855, 875) used during the greyscale update mode and (b) a standard reset pulse (610, 660) used during the monochrome update mode. Also, a monochrome update waveform (600, 650) includes a standard reset pulse (610, 660) whose duration is substantially less than a duration of an over-reset pulse (815, 835, 855, 875) used in a greyscale update waveform (800, 820, 840 and 860). The monochrome update mode is used in combination with the greyscale update mode when possible.