WO2013072453A2

WO2013072453A2 - Apparatus and method for driving a display

Info

Publication number: WO2013072453A2
Application number: PCT/EP2012/072817
Authority: WO
Inventors: Pierre de Greef
Original assignee: Tp Vision Holding B.V.
Priority date: 2011-11-16
Filing date: 2012-11-16
Publication date: 2013-05-23
Also published as: WO2013072453A3

Abstract

A display drive apparatus drives a display (101) having a backlight (105) and a transmittance panel (107) comprising an array of N lines and M columns of transmittance elements for modulating the light from the backlight (105). A receiver (109) receives a plurality of time sequential frames to be displayed. A backlight driver (111) generates a backlight drive signal to switch the backlight on for at least one time interval of each frame. A transmittance panel driver (113) generates an output image by performing at least one transmittance panel drive sequence for each frame where each transmittance panel drive sequence comprises P line address operations with each line address operation providing M transmittance values corresponding to M columns of transmittance elements. Each drive sequence comprises fewer than N line address operations thereby providing faster addressing. Each sequence may e.g. address a subset of lines or may address a plurality of lines in parallel with the same value.

Description

FIELD OF THE INVENTION

The invention relates to a display drive apparatus and a method of driving a display, and in particular, but not exclusively to driving of displays for presentation of three dimensional images.

BACKGROUND OF THE INVENTION

In order to provide a smooth user experience, it is desirable for displays for video images to provide a high frame rate. However, in order to provide high image quality, it is required that the displays are able to update the presented images sufficiently fast to avoid cross-talk between sequential images. This is particularly important for three dimensional (3D) displays where different views are presented time sequentially. In such displays cross-talk will not only be temporal cross-talk but will also affect the three dimensional experience and may give rise to perceived ghost imaging.

3D televisions are currently being introduced in the low/mid-range market. In the 3D mode these sets have a limited 3D performance with the cross talk between the left and right images typically being the most significant image degradation.

Stereoscopic display systems using active shutter glasses are very attractive, as they do not compromise power efficiency and picture quality when used in a conventional two-dimensional viewing mode. In a 3D viewing mode, the left and right images are displayed as alternating fields with synchronised shutter glasses being used to separate the images for the viewer's left and right eye respectively. During the addressing of each new field, shutter glasses are used to block the light towards either or both the left and right eye. To reduce crosstalk between the images for the left and right eye and to reduce power consumption, the backlight is preferably turned off locally when the related image content is not to be transferred to the left or right eye. This is typically during the transition period of the shutter glasses and of the liquid crystal cells modulating the backlight and.

In disparity areas of stereoscopic images, the left and right view will typically have very different content. The parallax at these locations results in the pixels of the Liquid Crystal (LC) panel being driven with substantially different values. Unfortunately the temporal optical response of LC-panels is relative slow which results in the change in transmittance values between the left and right images typically not being completed within the available time. This results in an interaction between the left and the right image and results in cross talk between the images that can be perceived by a user.

The same effects apply to color sequential display systems, resulting in interaction between the primary coloured images that can be perceived as discolouring and desaturation.

Hence, an improved approach for driving a display would be advantageous and in particular an approach allowing increased flexibility, facilitated implementation, reduced cross talk, improved image quality and/or improved performance would be advantageous.

SUMMARY OF THE INVENTION

Accordingly, the Invention seeks to preferably mitigate, alleviate or eliminate one or more of the above mentioned disadvantages singly or in any combination.

According to an aspect of the invention there is provided display drive apparatus for driving a display having a backlight and a transmittance panel comprising an array of N lines and M columns of transmittance elements for modulating the light from the backlight, the display drive apparatus comprising: a receiver for receiving a plurality of time sequential frames to be displayed by the display; a backlight driver for generating a backlight drive signal to switch the backlight on for at least one time interval of each frame; a transmittance panel driver for generating an output image from the display corresponding to the input image data for the frames by performing at least one transmittance panel drive sequence for each frame, each transmittance panel drive sequence comprising P line address operations, each line address operation providing M transmittance values to the transmittance panel corresponding to M columns of transmittance elements; wherein P is smaller than N.

The invention may provide improved image quality in many scenarios, and/or may facilitate implementation and/or reduce complexity. The approach may allow reduced cross-talk between sequential images. In particular, for time sequential three dimensional image displays, reduced cross-talk between left and right images may be achieved. The display drive apparatus may in some embodiments provide improved trade-off between spatial resolution on the one hand and brightness and/or transition time degradation on the other hand. The approach may in particular allow improved compensation and/or mitigation for delays in adaptation of the transmittance elements. A more accurate control of the light output of individual pixels may be achieved in many embodiments.

In particular, the system may improve the addressing speed for the image by not addressing each individual line of the display separately in each transmittance panel drive sequence. This may allow increased time for transmittance elements to transition towards the appropriate transmittance value from the value of the previous frame. The increased time for transmittance may be achieved by sacrificing some spatial resolution. However, this reduction may often be acceptable and/or can be compensated for thereby achieving an improved overall user experience and perceived image quality. In particular, for time sequential 3D view images, the cross talk between the right and left eye images may be substantially reduced, thereby providing an improved 3D experience. In some embodiments, increased display brightness and/or power efficiency may be achieved.

The backlight may be a pulsed backlight which is only active for part of the frame. The improved transmittance element settling time may allow increased duration of the pulsed backlight (and thus increased brightness) and/or may allow the transmittance elements to be closer to the desired value when the backlight is switched on.

The transmittance panel may specifically be a Liquid Crystal (LC)

transmittance panel and each transmittance element may be an LC pixel element.

Each transmittance panel drive sequence may cover the display area such that a full size image is generated by the display. Each transmittance panel drive sequence may perform an addressing of lines of the display from the top to the bottom of the display.

In accordance with an optional feature of the invention, each transmittance panel drive sequence addresses only a subset of the N lines of the transmittance elements.

This may provide improved image quality and/or facilitated implementation or operation in many embodiments. In particular, it may allow improved trade-off between spatial resolution on one hand and cross talk and/or display brightness on the other hand.

The subset may specifically comprise every other line of the N lines. The subset of N lines may cover the display area, and may specifically result in a continuous pattern of lines over the entire display area.

In accordance with an optional feature of the invention, subsequent transmittance panel drive sequences for same view frames comprise different subsets of the N lines of transmittance elements.

This may provide improved perceived image quality. The transmittance panel drive sequences for a given viewpoint (e.g. a left view or a right view) may cycle through a number of different subsets. The subsets may be disjoint and may specifically combine to cover all lines. Thus, each of the N lines may belong to one, and possibly only one, of the subsets.

In some embodiments the subsequent transmittance panel drive sequences for same view frames may be for the same frame. Thus, in some scenarios a plurality of transmission panel drive sequences may be performed for each frame. The plurality of transmission panel drive sequences may combine to address subsets that include all N lines.

In some embodiments, each frame may comprise two transmission panel drive sequences with the first covering all even numbered lines and the second covering all odd numbered lines (or vice versa).

In accordance with an optional feature of the invention, at least some of the P line address operations jointly address a plurality of the N lines in with the same M transmittance values.

The line address operations may address a plurality of lines in parallel with the same transmittance values being provided in parallel to transmittance elements of a plurality of lines of the display.

The line address operations may specifically simultaneously drive a pair of adjacent lines of the display. Thus a dual address line operation may be performed.

In accordance with an optional feature of the invention, the N lines are divided into P groups and wherein each of the P line address operations apply M transmittance values to the lines of one group of the P groups.

The transmission panel drive sequence may comprise a number of groups which do not have any overlap and which together include all the display lines. Thus, each of the N display lines may be included in one and only one of the groups.

Each group may in many scenarios advantageously comprise adjacent lines. In many scenarios each group may advantageously comprise two lines.

In accordance with an optional feature of the invention, the transmittance panel driver is arranged to perform a subsequent transmittance panel drive sequence for a frame to be displayed, the subsequent transmittance panel drive sequence comprising applying M transmittance values to a subset of the lines of at least one of the P groups. This may improve image quality in many scenarios. In particular, it may in many scenarios provide improved vertical resolution as the subsequent transmittance panel drive sequence may be used to provide a differentiation between the lines included in the subset addressed in the second transmission panel drive sequence and the lines which are not.

In accordance with an optional feature of the invention, the transmittance panel driver is arranged to vary the allocation of the N lines into the P groups between subsequent same viewpoint frames.

This may provide improved perceived image quality in many scenarios.

In accordance with an optional feature of the invention, the input signal comprises a three dimensional video signal comprising frames alternating between right view frames and left view frames.

The invention may provide particularly advantageous performance for display systems for presenting three dimensional images by sequentially presenting images for the left and right eyes. In particular, cross talk between left and right eye images may in many scenarios be reduced.

In accordance with an optional feature of the invention, the N lines are divided into a first subgroup of lines for displaying right view frames and a second subgroup of lines for displaying left view frames; and wherein the P line address operations for a transmittance panel drive sequence for right view frames comprises line address operations for lines of the first subgroup of lines and the P line address operations for a transmittance panel drive sequence for left view frames comprises line address operations for lines of the second subgroup of lines.

This may provide a particularly efficient three dimensional image rendering and may in particular reduce cross talk between left and right eye images may in many scenarios.

In accordance with an optional feature of the invention, the transmittance panel driver is arranged to further perform a transmittance panel black drive sequence for the right view frames, the transmittance panel black drive sequence driving the transmittance values for transmittance elements of lines of the first group to a maximum light blocking.

This may provide a particularly efficient three dimensional image rendering and may in particular reduce cross talk between left and right eye images in many scenarios. The transmittance panel black drive sequence may specifically drive the transmittance values to a maximum light blocking by setting the transmittance value to the value corresponding to the lowest transmittance for the transmittance element. Similarly to the right view frames, the transmittance panel driver may be arranged to further perform a transmittance panel black drive sequence for the left view frames, the transmittance panel black drive sequence driving the transmittance values for transmittance elements of the second group to a maximum light blocking.

In accordance with an optional feature of the invention, the transmittance panel driver is arranged to further perform at least two transmittance panel black drive sequences for the right view frames, each transmittance panel black drive sequence driving the transmittance values for transmittance elements of lines of the first group to a maximum light blocking, at least one of the two transmittance panel black drive sequences being performed at least partially during a vertical blanking interval for a left view frame.

The feature may provide improved image quality and may specifically reduce cross talk by providing a darker cross talk image. The transmittance panel black drive sequences may specifically drive the transmittance values to a maximum light blocking by setting the transmittance value to the value corresponding to the lowest transmittance for the transmittance element.

In accordance with an optional feature of the invention, at least one line of the first subgroup of lines and at least one line of the second subgroup of lines correspond to two lines of the transmittance panel with interleaved pixels.

This may provide improved image quality in many scenarios. In particular, it may allow improved perceived line resolution at the expense of reduced column resolution. The interleaving may specifically be such that the transmittance elements of the first and second subgroup of lines are arranged in a checkerboard pattern. Thus the right view transmittance elements and left view transmittance elements may be arranged in a checkerboard format.

In accordance with an optional feature of the invention, each of the N lines comprise an alternating pattern of right view transmittance elements allocated for displaying right view frames and left view transmittance elements allocated for displaying left view frames, the N lines being divided into a first group of lines and a second group of lines, the right view transmittance elements of the first group of lines being spatially offset relative to the right view transmittance elements of the second group of lines; wherein the transmittance panel driver is arranged to, for a right view frame, perform a first right view transmission panel drive sequence for the first group of lines and a second right view transmission panel drive sequence for the second group of lines, the right view transmission panel drive sequence providing right view transmittance values for the right view transmittance elements and black driving transmittance values for the left view transmittance elements.

This may provide improved image quality in many scenarios. In particular, it may allow improved perceived line resolution at the expense of reduced column resolution. The offset may specifically correspond to a transmittance element size resulting in the transmittance elements of the display being arranged in a checkerboard pattern. Thus the right view transmittance elements and left view transmittance elements may be arranged in a checkerboard format.

In accordance with an optional feature of the invention, the transmittance panel driver is arranged to perform a plurality of transmittance panel drive sequences for each frame.

This may improve image quality in many scenarios.

According to an aspect of the invention there is provided a method of driving a display having a backlight and a transmittance panel comprising an array of N lines and M columns of transmittance elements for modulating the light from the backlight, the method comprising: receiving a plurality of time sequential frames to be displayed by the display; generating a backlight drive signal to switch the backlight on for at least one time interval of each frame; generating an output image from the display corresponding to the input image data for the frames by performing at least one transmittance panel drive sequence for each frame, each transmittance panel drive sequence comprising P line address operations, each line address operation providing M transmittance values to the transmittance panel corresponding to M columns of transmittance elements;wherein P is smaller than N.

These and other aspects, features and advantages of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which

FIG. 1 is an illustration of examples of elements of a display system in accordance with some embodiments of the invention;

FIG. 2 illustrates an example of a timing for addressing a display in accordance with prior art;

FIG. 3 illustrates an example of an addressing approach for a display in accordance with prior art; FIG. 4 illustrates an example of an addressing approach for a display in accordance with prior art;

FIGs. 5 to 8 illustrate examples of addressing approaches for a display in accordance with some embodiments of the invention;

FIGs. 9 illustrates an example of a checkerboard pattern; and

FIG. 10 illustrates an example of an addressing approach for a display in accordance with some embodiments of the invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

The following description focuses on embodiments of the invention applicable to a display driver and system for displaying three dimensional images by alternating between images for the viewer's eyes. However, it will be appreciated that the invention is not limited to this application but may be applied to many other display systems and applications including traditional two dimensional video sequences.

FIG. 1 illustrates an example of a display system in accordance with some embodiments of the invention. The display system comprises a display driver 103 which drives a backlit display 101.

FIG. 1 illustrates an example of a display system in accordance with some embodiments of the invention. The display system comprises a display 101 driven by a display driver 103. It will be appreciated that although the display 101 and the display driver 103 are illustrated as separate functional blocks they may be integrated in the same device. Specifically, the display driver 103 and the display 101 may be implemented as a single display unit, such as e.g. a computer monitor, a video monitor, or a television.

The display 101 comprises a backlight 105 and a transmittance panel 107. The backlight 105 provides light which falls on the transmittance panel 107. The transmittance panel 107 comprises a number of transmittance elements, typically arranged as an array of elements. Each of transmittance elements modulate the light by a transmittance value that can be controlled by an electrical signal. Thus, the transmittance panel 107 can modulate the incident light from the backlight to change the light transmission of the individual transmittance element. Thus, each transmittance element corresponds to a pixel of the display. This pixel modulation allows an image to be rendered. As a typical example, the transmittance panel 107 may be implemented using liquid crystal technology, and thus the display 101 may specifically be an LC display. The transmittance panel 107 comprises a plurality of transmittance elements which are arranged in an array of N lines and M columns. Typically, the N lines will be horizontal lines and the columns will be vertical when the display in in use in a normal operational configuration. However, it will be appreciated that other arrangements are possible including arrangements where the lines are vertical and the columns horizontal when in use.

The display driver 103 comprises a receiver 109 which receives a plurality of time sequential frames to be displayed by the display. Each frame corresponds to a frame/two dimensional image to be displayed by the display 101. In the specific example, the frames alternate between an image for the right eye and a corresponding image for the left eye. Thus, the frames are provided in pairs of a right view frame and a left view frame which together form a single three dimensional image.

The display driver 103 is arranged to present the frames by controlling the backlight 105 and the transmittance panel 107. Accordingly, the display driver 103 comprises a backlight driver which drives the backlight 105 and a transmittance panel driver 113 which is arranged to drive the transmittance panel 107. The backlight driver 111 and transmittance panel driver 113 coordinate to provide a backlight and transmittance values that result in the images of the frames being rendered by the display 101.

In the example, the display 101 presents the sequential images for the right and left eyes. The backlight driver 111 is arranged to only switch the light on for part of the duration of each frame. The time interval of a frame is also referred to as a field. Thus, the backlight driver operates the backlight to be on for only part of a field. The backlight driver is furthermore arranged to drive shutter glasses synchronously to the backlight and the fields. Thus, the shutter glasses are driven such that the left eye shutter is open during the backlight- on time interval for the left eye frame but off during the backlight-on time interval of the right eye frame, and vice versa for the right eye shutter. Thus, the display system is a field- sequential stereoscopic display system which alternates the rendering of the left and right images on the transmittance panel 107 with the backlight 105 synchronously exposing the images when the appropriate shutter glass is set to be transparent while the other shutter glass is set to be non-transparent.

One of the main issues impacting image quality in backlight displays is the delay in transitioning the transmittance elements from the transmittance value of the previous frame to the transmittance value required for the current frame. Indeed, in order to ensure that the frames are perceived as moving images, the frame rate must be sufficiently high, and typically a frame rate of at least 120 Hz is used for field-sequential stereoscopic display thereby providing a 3D image rate of at least 60 Hz. However, for e.g. LC transmittance elements, the transition time may be high compared to the relative high frame rate. Therefore, often the LC elements may not be able to transition sufficiently.

This may be particularly critical for field-sequential stereoscopic displays.

Indeed, for stereoscopic images, the left and right views will have different content for objects positioned towards the front in order to provide a parallax creating a depth

impression. However, as the temporal response of LC panels is relative slow, this causes an interaction between the left and the right image. This picture quality artefact is perceived by the viewer as L/R crosstalk and may e.g. give rise to the perception of ghost images.

FIG. 2 illustrates an example of the timing of a conventional driving of a field- sequential stereoscopic display. In the example, the stereo-sequential display runs at twice the image rate of the 3D video source, which is typically 60 Hz. This corresponds to a panel addressing and Vertical Blanking Interval (VBI) period of 8.3 ms. In the example, the backlight is switched on or off for the entire image area as a whole, i.e. there is no local variations of the backlight. This reduces cost and is e.g. suitable for mid or low end LCD- TVs.

A video stream may typically be provided to a display system in a sequence of consecutive frames with each frame being represented by a first interval in which the image pixel data is provided serially followed by a period without image data. This time interval is then followed by the image pixel data for the next frame. This timing approach originates from historical CRT displays wherein the time period at the end of the frame was used to return the electron ray to the top of the screen. The time interval without image data is known as the vertical blanking interval (VBI).

A typical field-sequential stereoscopic display may begin to address the pixels of the display starting at line 0 and progressing towards line 1079 as shown in FIG. 2. When line 0 is addressed, i.e. when the transmittance values are transferred to the transmittance elements of line 0, the transmittance elements of this line starts to transition from the value of the previous frame towards the new value. As line 0 is addressed first, the transmittance elements of this line have a relatively long time to perform the transition. The system then proceeds to address line 1 resulting in the transmittance elements thereof beginning the transition. As line 1 is addressed after line 0, the transmittance elements of this line have less time to reach their final value. The system then proceeds one line at a time until the last line (line 1079 in the example) is addressed. Following the addressing of line 1079, all transmittance elements have been set to the transmittance value of the current frame, and the system enters the VBI period. Following the VBI, the process initiates for the next frame by the system addressing line 0 with the transmittance values of the next frame.

Thus, as illustrated, the only duration in which all transmittance values are set to the value for the current frame is during the VBI of the frame. In the example, the backlight is accordingly switched on only during the VBI. Furthermore, the shutter glasses are aligned with the backlight.

However, typically the VBI is only around 10% of the total frame period and accordingly images cannot be rendered for around 90% of the time as both the left and the right images are partially rendered on the transmittance panel at these times. This reduces the potential brightness of the image.

Furthermore, whereas the LC transmittance elements that are addressed early have a relatively long time to transition towards their desired value, the late addressed transmittance elements only have a very short time to transition towards their desired value. This results in cross talk from previous frames. Reducing the duration of the backlight to provide more time for the transmittance elements to settle reduces the duty cycle and reduces the brightness. Furthermore, the duty cycle is already 10%> and thus does not provide much scope for any reduction. Delaying the backlight-on duration may reduce cross talk for the last addressed lines but will result in an overlap with the addressing of the first lines for the following frame and will consequently introduce cross talk for the first lines of the display.

Thus, there is an inherent trade-off between brightness and cross-talk between images. This is a particularly critical trade-off for field-sequential stereoscopic displays where brightness is already reduced due to the alternating between left eye and right images and where cross-talk is particularly noticeable due to the simultaneous nature of the paired images and the potential high difference between foreground and background objects.

It has been proposed to use an addressing that employs a time base which is not dependent on the input video signal. In such cases, the addressing may be faster than the input data addressing (e.g. using a frame buffer to decouple the addressing time base from the time base of the provided signal) thereby allowing more time for either a longer backlight duration or for settling of the transmittance elements. However, such addressing typically only reduces the addressing time relatively little and therefore tends to only provide a relatively minor improvement. For example, for a 120Hz display, the VBI is typically around 10% of the frame duration, i.e. around 0.8 msecs. Using another time base may typically allow this to be increased to around 2-3 msecs which is less than desired and further requires substantial amounts of frame memory.

The system of FIG. 1 is arranged to increase the time available for the backlight to be on. This increased time may be used to provide increased brightness or to provide increased transmittance element settling time thereby reducing cross talk. In many scenarios, a trade-off reducing both cross talk and increasing brightness compared to conventional approaches is provided. Furthermore, this is achieved without necessitating any additional frame memory.

The system of FIG. 1 is particularly arranged to perform one or more transmittance panel drive sequences for each frame. Each of these transmission panel drive sequences includes a number of line address operations where each address operation sets the transmittance value of M transmittance elements, where M is the number of columns in the display. Thus, specifically, each transmission panel drive sequence can address (and thus set transmittance values) for M transmittance elements corresponding to one line of the display.

Each transmission panel drive sequence can provide an image for the whole display area and is sufficient to render a complete image to the viewer. Each transmission panel drive sequence covers the display outline/ area and can be performed in a top down scanning approach, e.g. starting from lower line numbers and moving towards higher line numbers. However, each transmission panel drive sequence includes fewer line address operations than there are lines on the display. Thus, if the display contains N lines, the transmission panel drive sequence includes only P address line operations where P is smaller than N. Indeed, in many embodiments P is substantially equal to N divided by 2.

The approach may thereby increase addressing speed thus allowing for increased time for switching the backlight on and/or for providing a longer transmittance element settling time. This may be achieved without requiring any additional frame buffering and may thus be achieved using low complexity implementations. As the transmission panel drive sequence may include fewer individual transmittance element addressing operations than there are transmittance elements in the display, the spatial resolution may be reduced. However, such a spatial resolution impact may be mitigated and compensated for in different ways as will be described in the following.

In some embodiments, each transmission panel drive sequence may only address a subset of the lines of the display. In particular, in some embodiments, each transmission panel drive sequence may only address alternate lines of the display. Thus, in such an example, each transmission panel drive sequence can be performed in half the time it takes for a conventional addressing of all lines of a display. This may provide substantially increased time in which the displays have been set appropriately and this may be used to increase the settling time and/or the backlight duration.

In such embodiments a plurality of transmission panel drive sequences may be performed for each frame. In particular, the N lines of the display may be divided into a number of subsets. Each subset is then addressed in one transmission panel drive sequence with the transmission panel drive sequences for the different subsets being performed sequentially. The subsets are distributed across the display, i.e. each transmission panel drive sequence may only address a subset of lines but these are distributed across the display area such that they correspond to a full image. Consequently, an improved distribution of cross talk across the image is achieved rather than this being concentrated at the top and/or bottom of the display.

Specifically, the system may first perform a transmission panel drive sequence which includes all even (or odd) lines of the display. This sequence can be performed in half the time of a conventional transmittance panel addressing. After the first transmission panel drive sequence, the system may proceed to perform a second transmission panel drive sequence but this time the sequence will include all the odd (or even) lines of the display. Thus, the total of the two transmission panel drive sequences will address all lines of the display. Furthermore, whereas the combined time of the two transmission panel drive sequences may be as long as a conventional addressing process, any cross talk from insufficient time to settle for the transmittance elements will not be concentrated at the top and/or bottom of the screen but will be smoothly distributed across alternate lines of the entire display.

The approach may be illustrated with a specific example. Firstly, for comparison FIG. 3 illustrates a conventional addressing approach where the transmittance panel 107 is driven in a conventional fashion as described with respect to FIG. 2.

The examples are provided for consecutive frames which alternate between maximum and minimum brightness, i.e. between alternating black and white frames. The example is further based on a blinking backlight for which both the phase (timing) and duty cycle can be varied. In the examples, the transmittance panel is a progressively addressed LC panel running at 120 Hz with the transitional characteristics corresponding to measurements made on a physical LC panel.

FIG. 3 first illustrates the transmittance panel 301. For clarity only ten lines and one column are shown (i.e. ten pixels is illustrated for each time interval). The transmittance panel switches between low transmittance values (illustrated by lighter colors) corresponding to the black image (in this case the right image) and high transmittance values (illustrated by darker colors) corresponding to the bright image (in this case the left image). FIG. 3 furthermore indicates addressing sequences or transmission panel drive sequences by arrows 303, 305. FIG. 3 also illustrates the backlight 307 which is switched on only for part of the time during each field/ frame. The backlight-on status is indicated by a white section in a grey line. FIG. 3 also illustrates the rendered left image 309 which is dark except for when the backlight is on and the left shutter of the shutter glasses is transparent. In addition, FIG. 3 illustrates the rendered right image 311 which is dark except for when the backlight is on and the right shutter of the shutter glasses is transparent.

In the example of FIG. 3, the display system may initially be displaying the dark image for the left eye. Thus, the transmittance elements will be set at a very low transmittance values (indicated by a light colour of the transmittance panel 301). At the beginning of the right frame field, an addressing sequence 303 is initialised which

sequentially addresses each line of the transmittance panel 301. As soon as a line has been addressed, the transmittance elements of that line starts to change towards a high

transmittance value, corresponding to a gradual darkening of the shade of transmittance elements in FIG. 3. Clearly, the last addressed lines will lag behind the early addressed lines. At a suitable time the backlight 307 is switched on resulting in the display radiating the right eye image 311. Thus, as illustrated, a brighter right eye image 311 is presented when the backlight is switched on as the transmittance elements have a high transmittance value as set by the addressing 303 (it is noted that a darker shade of the transmittance element in the panel 301 of FIG. 3 corresponds to a higher transmittance value and thus to more light radiating from the display, i.e. darker areas of the transmittance panel 301 representation of FIG. 3 will result in brighter image areas in the radiated image 311).

It is noted that the backlight-on duration in this example corresponds to the VBI and has been positioned with a delay relative to the VBI. This may allow some time for the last addressed LC transmittance elements to at least partly transition. However, it also means that the transmittance elements of the first lines have already been addressed by the addressing 305 for the subsequent left image and thus have already started to transition towards the new value. Accordingly, an amount of cross talk occurs as indicated by the slightly darker shading in the upper right and lower left of the right eye image 311. Indeed, it is worth noting that cross talk in this example is substantial, and is concentrated at the upper and lower sections of the display. Indeed, as illustrated, the crosstalk-level depends significantly on the vertical position in the display. At the centre, the crosstalk level is low, yet at the top and bottom light of the intended field is missing and light of the alternate field is leaking, causing crosstalk

It will be appreciated that the complementary scenario arises for the left eye image 309 (where it will be appreciated that since the image is black, cross talk results in brighter image sections corresponding to the higher transmittance values (i.e. the lighter areas of 301)).

In the example of conventional addressing of FIG.3, the time base of the incoming video signal is maintained for the addressing. If the system instead employs a faster addressing time base independent of the incoming video signal, it is possible to extend the VBI as illustrated in the corresponding example of FIG. 4. In this example, the panel addressing is performed at a higher rate, and in the particular example is performed by addressing each line in 5.1 resulting in a VBI with a duty cycle of 33%.

As can be seen in FIG. 4, this may substantially improve the brightness potential and reduce the relative amount of cross talk. However, the cross talk is still more than desired and is furthermore concentrated at the top and bottom of the display.

FIG. 5 illustrates an example of an addressing approach in accordance with some embodiments of the invention. In the example, each transmission panel drive sequence is performed on only a subset of the lines of the display. In the specific example, two transmission panel drive sequences 501, 503 are performed for each right eye frame and two transmission panel drive sequences 505, 507 are performed for each left eye frame. Each transmission panel drive sequence is achieved in half the time of a full line addressing sequence and thus the two transmission panel drive sequences can be performed in each frame. Thus, the approach uses faster transmission panel drive sequences which are achieved by driving only a subset (in this case only half) of the display lines in each sequence. In the example, this interlaced driving approach does not reduce the overall cross talk compared to the approach of FIG. 3. However, it achieves that the cross talk is spread more evenly across the entire display thereby providing a three dimensional image which is perceived to be of higher quality and with less noticeable cross talk.

In some embodiments, the transmittance panel driver 113 is arranged to perform one or more of the line address operations as a parallel addressing of a plurality of display lines. Thus, a single line address operation may drive the transmittance values for a plurality of transmittance elements at the same time. As each line address operation sets only M transmittance values (corresponding to M columns of the display), the plurality of lines will be set to the same values. Thus, each transmittance value is simultaneously and in parallel applied to transmittance elements in more than one display line.

By addressing multiple lines in parallel each transmission panel drive sequence can address all N lines of the display using only P line address operations where P is smaller than N. Thus, fewer line address operations than the number of lines in display is needed to address the entire display. This may substantially reduce the time required for each transmission panel drive sequence thereby allowing more time for the backlight to be on and/or for transitioning of the transmittance elements.

Specifically, the panel driver 113 may be arranged divide the N lines into P groups with each of the transmission panel drive sequences comprising P line address operations where each line address operations applies M transmittance values to the lines of one of the P groups. Thus, the N lines may be divided into P groups with at least some groups containing a plurality of lines. Typically, the lines of each group will be adjacent lines.

As a specific example, the panel driver 113 can divide the N lines into N/2 groups by pairing adjacent even and odd lines. Each line address operation accordingly addresses two lines in parallel, namely an odd and an even line. In this way two display lines are set to transmittance values of the new image simultaneously and in parallel thereby halving the time required compared to an individual addressing of each line. As a result, the transmission panel drive sequence can be performed in half the time of a normal transmission panel drive sequence addressing each line, thereby freeing up substantial time for increased backlight and/or transmittance element transition time. As a result of this approach, the vertical spatial resolution is halved but this may be an acceptable trade-off for the improved brightness and/or reduced cross talk that can be achieved. Furthermore, as described later, further techniques can be applied to mitigate for such resolution loss.

FIG. 6 illustrates an example wherein the transmission panel drive sequences comprises line address operations with parallel driving of multiple (and specifically two) adjacent lines and with each transmission panel drive sequence addressing all lines of the display. As can be seen each transmission panel drive sequence is performed in half the time thereby increasing the VBI to a much longer duration. Indeed, in the example, each line may be addressed in 7 corresponding to the addressing time of the example of FIG. 3 yet result in a VBI of 55% of the frame duration. The approach may also be combined with the use of an addressing which is independent of the video signal time base. This may e.g. allow an addressing of each line in around 5 with the potential of the VBI increasing to around 66% of the frame duration. In such multiple line address approaches, the transmission panel drive sequence may accordingly be reduced substantially and indeed may often be reduced to half or more than a conventional full addressing transmission panel drive sequence. This may allow for more than one transmission panel drive sequence to be performed for each frame, and in some embodiments the panel driver 113 may be arranged to perform a plurality of transmission panel drive sequences for each frame.

Indeed, in the example of FIG.6, each transmission panel drive sequence is halved and this is used to perform two transmission panel drive sequences for each frame. In the example of FIG. 6, the two transmission panel drive sequences address the same lines with the same data (corresponding to an LLR addressing mode). This may increase the transition time for the LC transmittance elements as a second "refresh" setting tends to increase the transition speed for LC elements (in essence addressing an LC element twice with the same video-data improves the LC response as the variations of the pixel-capacitor value are compensated by recharging during the second address-cycle).

In other embodiments, slightly different drive values may be used in the different transmission panel drive sequences for the same drive. For example, the value of the first transmission panel drive sequence may include an overdrive component such that the change in transmittance is emphasized resulting in a faster transition. The second

transmission panel drive sequence may then provide a value which is closer to the desired value (having less of an overdrive component) to guide the transmittance value closer to the desired value. Thus, the approach may allow overdrive correction to become more accurate as it has double the temporal resolution).

It should be noted that whereas the second transmission panel drive sequence may improve the image quality, the first transmission panel drive sequence already initiates the transition of the transmittance elements and thus the backlight does not need to wait for the second transmission panel drive sequence.

In some embodiments, the second or subsequent transmission panel drive sequence for a given frame may address only a subset of the lines of each group. E.g. the first transmission panel drive sequence may address all N lines of the display in line address operations of multiple (specifically two) lines. The second transmission panel drive sequence may only address one (or some) of each pair (group) of lines. The second transmission panel drive sequence may in this way be used to differentiate between the lines of a group and this may be used to set the transmittance value of the different lines to different values. This approach may be used to improve the resulting perceived spatial resolution. As a specific example, a first transmission panel drive sequence may address the lines in pairs of odd and even lines thereby providing only half the horizontal spatial resolution. Specifically, the first transmission panel drive sequence can address two adjacent lines with the same data corresponding to the transmittance values of the even lines. In the second transmission panel drive sequence only the odd lines are addressed using the appropriate image-data for the odd lines. In this way, the second transmission panel drive sequence restores the full spatial resolution although this may be with increased cross talk relative to the even lines as the transition time before the backlight is switched on is reduced (and may even be negative). However, the first transmission panel drive sequence effectively pre-charges the odd line LC elements with the even-line data. Statistical analysis has shown that this typically provides an improved response. Indeed, often the transmittance elements will be addressed twice with almost the same video-data. This improves the LC response as the variations of the pixel-capacitor value are compensated by recharging during the second address-cycle. When the image data is very different, i.e. when the pre-charge may be significantly different from the desired value, a minor vertical resolution blur may typically be experienced but this is typically insignificant in view of the potential benefits.

In some embodiments, the grouping of the lines into groups that are addressed together may be varied between subsequent frames for the same viewpoint, i.e. between two frames for the left eye or two frames for the right eye. This variation of the allocation of lines into simultaneously addressed groups may increase the perceived spatial resolution.

Specifically, in embodiments wherein each simultaneously addressed group comprises two adjacent lines, the pairing of a given line may alternate between being with the previous line and being with the following line. Thus, instead of always paring the same lines, (0 and 1), (2 and 3), (4 and 5), etc, every other frame may use a different pairing, such as (1 and 2), (3 and 4), (4 and 5) ... etc.

The specific approach may be illustrated by the following table: Frame Field/ Time Display lines Source lines

Drive (sec)

Sequence

0 0 left 0/240 (O&l), (2&3), (4&5), ... av(0,l), av(2,3), av(4,5), ...

0 1 left 1/240 (O&l), (2&3), (4&5), ... av(0,l), av(2,3), av(4,5), ...

0 2 right 2/240 (O&l), (2&3), (4&5), ... av(0,l), av(2,3), av(4,5), ...

0 3 right 3/240 (O&l), (2&3), (4&5), ... av(0,l), av(2,3), av(4,5), ...

1 4 left 4/240 (1&2), (3&4), (5&6), ... av(l,2), av(3,4), av(5,6), ...

1 5 left 5/240 (1&2), (3&4), (5&6), ... av(l,2), av(3,4), av(5,6), ...

1 6 right 6/240 (1&2), (3&4), (5&6), ... av(l,2), av(3,4), av(5,6), ...

1 7 right 7/240 (1&2), (3&4), (5&6), ... av(l,2), av(3,4), av(5,6), ...

2 8 left 8/240 (O&l), (2&3), (4&5), ... av(0,l), av(2,3), av(4,5), ...

2 9 left 9/240 (O&l), av(O.l),

To illustrate the improved spatial resolution, the rendering of a single one pixel wide horizontal white line (with the image value of 1) on a black background (with the image value of 0) can be considered Assuming that the line is at line position 3, the following result may be achieved:

Frame Field / Time Display lines 0,1,2,3,4,5 Source lines 0,1,2,3,4,5

Drive (sec)

Sequence

0 0 left 0/240 0.0,0.0,0.5,0.5,0.0,0.0 0, 0, 0, 0, 1, 0, 0

0 1 left 1/240 0.0,0.0,0.5,0.5,0.0,0.0 0, 0, 0, 0, 1, 0, 0

0 2 right 2/240 0.0,0.0,0.0,0.5,0.5,0.0 0, 0, 0, 0, 1, 0, 0

0 3 right 3/240 0.0,0.0,0.0,0.5,0.5,0.0 0, 0, 0, 0, 1, 0, 0

1 4 left 4/240 0.0,0.0,0.5,0.5,0.0,0.0 0, 0, 0, 0, 1, 0, 0

1 5 left 5/240 0.0,0.0,0.5,0.5,0.0,0.0 0, 0, 0, 0, 1, 0, 0

1 6 right 6/240 0.0,0.0,0.0,0.5,0.5,0.0 0, 0, 0, 0, 1, 0, 0

1 7 right 7/240 0.0,0.0,0.0,0.5,0.5,0.0 0, 0, 0, 0, 1, 0, 0

2 8 left 8/240 0.0...

2 9 left 9/240 Hence the vertical luminance profile of this line will be 0.0, 0, 25, 0.50, 0.25, 0.0 corresponding to that which would be rendered by a High Definition TV. Thus, as illustrated the line will be displayed a unique position albeit as a low-pass filtered line.

In some embodiments, the lines of a display may be divided into two groups where one group is used for left view (or left eye) frames and the other group is used for right view (or right eye) frames. In this case, a transmission panel drive sequence for the left eye view is restricted to the lines of the left view group and a transmission panel drive sequence for the right eye view is restricted to the lines of the right view group. For example, the display may be divided into a group comprising the even lines and a group comprising the odd lines. The first group is then used to display the left eye images and the second group is used to display the right eye images. In this case, each transmission panel drive sequence needs to address only half the lines thereby resulting in a substantially reduced duration. However, the approach may result in a vertical spatial resolution which is reduced by a factor of two. However, this may be acceptable in many embodiments.

In such a system, the panel driver 113 may further be arranged to perform a second transmission panel drive sequence in each frame which drives the transmittance elements for the other group (i.e. the group not being addressed with image data) towards a maximum light blocking state, i.e. towards a minimum transmittance value. Thus, in this example, each frame contains at least a first transmission panel drive sequence which sets the transmittance values of the appropriate lines to display the image (i.e. either the odd or even lines) and a second transmission panel drive sequence which drives the transmittance elements of the other lines towards black. This transmission panel black drive sequence is used to prevent/ reduce cross talk between the left and right view images.

FIG. 7 illustrates an example wherein each right view frame comprises a transmission panel drive sequence addressing the lines used for the right view image as well as a transmittance panel black drive sequence setting the other lines to black.

Thus, in such a black data insertion approach, black video-data is inserted to reduce cross talk between subsequent frames. However, in order to provide sufficient time for inserting such black data, the system proceeds to divide the display into some lines which are used for right view frames and some lines that are used for left view frames. This results in each line only being used to display an image in every other frame and provides sufficient time to perform a transmission panel black drive sequence for the lines prior to the complementary image being displayed. The approach is similar to the previously described interlacing approach and specifically uses spatial interlacing of the black data insertion in order to trade-off spatial resolution for addressing speeds. As transmittance elements are now switching between a single view (being either left or right) and black, there is no direct interaction (crosstalk) between the left and right views (at least for the individual lines being used). Indeed, a significant advantage is that the left and right views do not share the same transmittance elements but are spatially interleaved. This may reduce the requirement for overdrive correction. In particular, LC elements switch from dark to bright substantially faster than from bright to dark. In approaches such as that illustrated in FIG. 7,the transmittance elements always start from a dark state when transitioning towards their image data given transmittance value thereby ensuring that this transition is in the direction which is faster. The transition towards dark may take longer but is typically performed earlier thereby providing more time for the transition.

Thus, as shown in FIG. 7 the addressing performed in each field treats the odd and even fields differently. Specifically, in the even fields the even lines are addressed with the left view while the odd lines are driven black; in the odd fields the even lines are driven black while the odd lines are addressed with the right view. To reduce the overlap of the left and right field, addressing of the lines driven towards black is separated from the addressing of image data. In this way left/ right image crosstalk is reduced.

In some embodiments the panel driver 113 is arranged to perform two or more transmittance panel black drive sequences for each frame wherein at least part of one of the transmittance panel black drive sequences is performed during the VBI of the other frame.

For example, as can be seen in FIG. 7, no addressing is performed during the VBI. During this time the transmittance elements are in the process of either transitioning towards the appropriate image value or towards black. In the example of FIG. 8, this unused time interval is used to perform a second transmittance panel black drive sequence which affects only the lines that are transitioning towards black. A substantial advantage of this extra addressing is that the varying pixel capacitance gets an extra recharge cycle during its transition towards black thereby improving the LC response and further reducing the left/right crosstalk. This is particularly suitable since the drive towards black is difficult to improve by using overdrive techniques (since the black value is already at the limit of the range).

In the previous example, the display was divided into lines for the right view image and lines for the left view image. In some embodiments, this division may be performed in the two dimensional plane. Specifically, the transmittance elements of the transmittance panel may be divided into right view transmittance elements and left view transmittance elements but such that each line contains both types of transmittance elements. Specifically, each line may alternate between transmittance elements allocated to the left view and transmittance elements allocated for the right view. Furthermore, the lines may be allocated into two different groups for which the right view transmittance elements (and the left view transmittance elements) are spatially offset relative to each other. As a specific example, all the even lines may start with a right view transmittance element, followed by a left view transmittance element, followed by a right view transmittance element etc. In contrast, the odd lines start with a left view transmittance element, followed by a right view transmittance element, followed by a left view transmittance element etc.

Thus, in the specific example the display may be divided into a checkerboard pattern as illustrated in FIG. 9 where light elements correspond to a left view transmittance element and dark elements correspond to a right view transmittance element. The lines are divided into a first group comprising the lines that start with a right view transmittance element (i.e. the even lines) and a second group comprising the lines that start with a left view transmittance element (i.e. the odd lines).

In this example, the system may use black insertion but in contrast to the approach of FIGs. 7 and 8, the approach uses a checkerboard pattern rather than a line pattern. However, this may complicate the addressing of the elements as each line address operation performs both image driving and black driving.

Specifically, the transmittance panel driver 113 may for a right view frame first perform a transmission panel drive sequence which sets right view transmittance values (i.e. corresponding to the provided image data values) for the right view transmittance elements and black driving transmittance values for the left view transmittance elements for all the even lines (i.e. for the first group of lines). Subsequently, a second transmission panel drive sequence is performed which sets right view transmittance values (i.e. corresponding to the provided image data values) for the right view transmittance elements and black driving transmittance values for the left view transmittance elements for all the odd lines (i.e. for the second group of lines). Following the two transmission panel drive sequences all right view transmittance elements are driven towards the appropriate image data transmittance value and all left view transmittance elements are driven towards black. At a suitable time the backlight may then be switched on to render the right view image. The complementary process is then performed for the left view frame. Thus, the transmittance panel driver 113 may first perform a transmission panel drive sequence which sets left view transmittance values (i.e. corresponding to the provided image data values) for the left view transmittance elements and black driving transmittance values for the right view transmittance elements for all the even lines (i.e. for the first group of lines). Subsequently, a second transmission panel drive sequence is performed which sets left view transmittance values (i.e. corresponding to the provided image data values) for the left view transmittance elements and black driving transmittance values for the right view

transmittance elements for all the odd lines (i.e. for the second group of lines). Following the two transmission panel drive sequences all left view transmittance elements are driven towards the appropriate image data transmittance value and all right view transmittance elements are driven towards black. At a suitable time the backlight may then be switched on to render the left view image.

Since the two transmission panel drive sequences do not perform any addressing during the VBI, an additional transmission panel drive sequence which drives all transmittance elements towards black can be inserted similarly to the example of FIG. 8.

Indeed, the example of FIG. 8 performs the following series of transmission panel drive sequences: odd_lines=Left,

even_lines=Black,

odd_lines=Black,

even_lines=Right,

odd_lines=Black,

even_lines=Black.

In order to implement a checkerboard pattern, this may be changed to the following series of transmission panel drive sequences (where the brackets indicate transmittance elements at an odd/even column position respectively): odd_lines=(Left/Black),

even_lines=(Black/Left),

odd_lines=(Black/Black),

even_lines=(Black/Right), odd_lines=(Right/Black),

even_lines=(Black/Black).

In other embodiments, the transmittance panel may be modified such that an addressing line of transmittance elements correspond to alternating pixels of two adjacent lines. For example, an odd and even addressing line may physically in the display be arranged with the transmittance elements interleaved such that one physical horizontal line comprises a transmittance element of an even addressing line next to a transmittance element of an odd addressing line next to a transmittance element of an even addressing line etc. Such a variation between the addressing lines and the physical position of the transmittance elements may be used to provide a checkerboard black insertion approach while maintaining the addressing approaches of FIG. 7 and 8.

Using a checkerboard approach may allow the loss of half the vertical resolution of the examples of FIG. 7 and 8 to be converted into a resolution loss of 0.7 in both the horizontal and vertical resolutions. Furthermore, the approach may result in 3D visual black-line alignment artefacts turning into a checkerboard pattern which is typically much less noticeable to a user.

I will be appreciated that whereas the different addressing schemes have been described individually the corresponding approaches and principles may be combined as appropriate.

For example, the black insertion may be combined with the parallel line addression. This may allow two vertically adjacent transmittance elements to share the same data while using a black insertion for alternating line pairs. This may result in a very fast addressing allowing for an increased VBI. An example of such an approach is illustrated in FIG. 10.

It will be appreciated that the above description for clarity has described embodiments of the invention with reference to different functional circuits, units and processors. However, it will be apparent that any suitable distribution of functionality between different functional circuits, units or processors may be used without detracting from the invention. For example, functionality illustrated to be performed by separate processors or controllers may be performed by the same processor or controllers. Hence, references to specific functional units or circuits are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization. The invention can be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be

implemented at least partly as computer software running on one or more data processors and/or digital signal processors. The elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the invention may be implemented in a single unit or may be physically and functionally distributed between different units, circuits and processors.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term comprising does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements, circuits or method steps may be implemented by e.g. a single circuit, unit or processor.

Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims do not imply any specific order in which the features must be worked and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus references to "a", "an", "first", "second" etc do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example shall not be construed as limiting the scope of the claims in any way.

Claims

CLAIMS:

1. A display drive apparatus for driving a display (101) having a backlight (105) and a transmittance panel (107) comprising an array of N lines and M columns of

transmittance elements for modulating the light from the backlight (105), the display drive apparatus comprising:

a receiver (109) for receiving a plurality of time sequential frames to be displayed by the display;

a backlight driver (111) for generating a backlight drive signal to switch the backlight on for at least one time interval of each frame;

a transmittance panel driver (113) for generating an output image from the display corresponding to the input image data for the frames by performing at least one transmittance panel drive sequence for each frame, each transmittance panel drive sequence comprising P line address operations, each line address operation providing M transmittance values to the transmittance panel (107) corresponding to M columns of transmittance elements;

wherein P is smaller than N.

2. The display drive apparatus of claim 1 wherein each transmittance panel drive sequence addresses only a subset of the N lines of the transmittance elements.

3. The display drive apparatus of claim 2 wherein subsequent transmittance panel drive sequences for same view frames comprise different subsets of the N lines of transmittance elements.

4. The display drive apparatus of claim 1 wherein at least some of the P line address operations jointly address a plurality of the N lines in with the same M transmittance values.

5. The display drive apparatus of claim 4 wherein the N lines are divided into P groups and wherein each of the P line address operations apply M transmittance values to the lines of one group of the P groups.

6. The display drive apparatus of claim 5 wherein the transmittance panel driver

(113) is arranged to perform a subsequent transmittance panel drive sequence for a frame to be displayed, the subsequent transmittance panel drive sequence comprising applying M transmittance values to a subset of the lines of at least one of the P groups.

7. The display drive apparatus of claim 5 wherein the transmittance panel driver

(113) is arranged to vary the allocation of the N lines into the P groups between subsequent same viewpoint frames.

8. The display drive apparatus of claim 1 wherein the input signal comprises a three dimensional video signal comprising frames alternating between right view frames and left view frames.

9. The display drive apparatus of claim 8 wherein the N lines are divided into a first subgroup of lines for displaying right view frames and a second subgroup of lines for displaying left view frames; and wherein the P line address operations for a transmittance panel drive sequence for right view frames comprises line address operations for lines of the first subgroup of lines and the P line address operations for a transmittance panel drive sequence for left view frames comprises line address operations for lines of the second subgroup of lines.

10. The display drive apparatus of claim 9 wherein the transmittance panel driver (113) is arranged to further perform a transmittance panel black drive sequence for the right view frames, the transmittance panel black drive sequence driving the transmittance values for transmittance elements of lines of the first group to a maximum light blocking.

11. The display drive apparatus of claim 9 wherein the transmittance panel driver (113) is arranged to further perform at least two transmittance panel black drive sequences for the right view frames, each transmittance panel black drive sequence driving the transmittance values for transmittance elements of lines of the first group to a maximum light blocking, at least one of the two transmittance panel black drive sequences being performed at least partially during a vertical blanking interval for a left view frame.

12. The display drive apparatus of claim 10 wherein at least one line of the first subgroup of lines and at least one line of the second subgroup of lines correspond to two lines of the transmittance panel with interleaved pixels.

13. The display drive apparatus of claim 9 wherein each of the N lines comprise an alternating pattern of right view transmittance elements allocated for displaying right view frames and left view transmittance elements allocated for displaying left view frames, the N lines being divided into a first group of lines and a second group of lines, the right view transmittance elements of the first group of lines being spatially offset relative to the right view transmittance elements of the second group of lines; wherein the transmittance panel driver (113) is arranged to, for a right view frame, perform a first right view transmission panel drive sequence for the first group of lines and a second right view transmission panel drive sequence for the second group of lines, the right view transmission panel drive sequence providing right view transmittance values for the right view transmittance elements and black driving transmittance values for the left view transmittance elements.

14. The display drive apparatus of claim 1 wherein the transmittance panel driver

(113) is arranged to perform a plurality of transmittance panel drive sequences for each frame.

15. A method of driving a a display (101) having a backlight (105) and a transmittance panel (107) comprising an array of N lines and M columns of transmittance elements for modulating the light from the backlight (105), the method comprising:

receiving a plurality of time sequential frames to be displayed by the display; generating a backlight drive signal to switch the backlight on for at least one time interval of each frame;

generating an output image from the display corresponding to the input image data for the frames by performing at least one transmittance panel drive sequence for each frame, each transmittance panel drive sequence comprising P line address operations, each line address operation providing M transmittance values to the transmittance panel (107) corresponding to M columns of transmittance elements; wherein P is smaller than N.